diff options
Diffstat (limited to 'Documentation')
299 files changed, 14036 insertions, 12653 deletions
diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX index ed3e5e949fce..f35473f8c630 100644 --- a/Documentation/00-INDEX +++ b/Documentation/00-INDEX @@ -24,8 +24,6 @@ DMA-ISA-LPC.txt - How to do DMA with ISA (and LPC) devices. DMA-attributes.txt - listing of the various possible attributes a DMA region can have -DocBook/ - - directory with DocBook templates etc. for kernel documentation. EDID/ - directory with info on customizing EDID for broken gfx/displays. IPMI.txt @@ -40,8 +38,6 @@ Intel-IOMMU.txt - basic info on the Intel IOMMU virtualization support. Makefile - It's not of interest for those who aren't touching the build system. -Makefile.sphinx - - It's not of interest for those who aren't touching the build system. PCI/ - info related to PCI drivers. RCU/ @@ -264,6 +260,8 @@ logo.gif - full colour GIF image of Linux logo (penguin - Tux). logo.txt - info on creator of above logo & site to get additional images from. +lsm.txt + - Linux Security Modules: General Security Hooks for Linux lzo.txt - kernel LZO decompressor input formats m68k/ diff --git a/Documentation/ABI/stable/sysfs-class-udc b/Documentation/ABI/stable/sysfs-class-udc index 85d3dac2e204..d1e2f3ec1fc9 100644 --- a/Documentation/ABI/stable/sysfs-class-udc +++ b/Documentation/ABI/stable/sysfs-class-udc @@ -55,14 +55,6 @@ Description: Indicates the maximum USB speed supported by this port. Users: -What: /sys/class/udc/<udc>/maximum_speed -Date: June 2011 -KernelVersion: 3.1 -Contact: Felipe Balbi <balbi@kernel.org> -Description: - Indicates the maximum USB speed supported by this port. -Users: - What: /sys/class/udc/<udc>/soft_connect Date: June 2011 KernelVersion: 3.1 @@ -91,3 +83,11 @@ Description: 'configured', and 'suspended'; however not all USB Device Controllers support reporting all states. Users: + +What: /sys/class/udc/<udc>/function +Date: June 2017 +KernelVersion: 4.13 +Contact: Felipe Balbi <balbi@kernel.org> +Description: + Prints out name of currently running USB Gadget Driver. +Users: diff --git a/Documentation/ABI/stable/sysfs-driver-aspeed-vuart b/Documentation/ABI/stable/sysfs-driver-aspeed-vuart new file mode 100644 index 000000000000..8062953ce77b --- /dev/null +++ b/Documentation/ABI/stable/sysfs-driver-aspeed-vuart @@ -0,0 +1,15 @@ +What: /sys/bus/platform/drivers/aspeed-vuart/*/lpc_address +Date: April 2017 +Contact: Jeremy Kerr <jk@ozlabs.org> +Description: Configures which IO port the host side of the UART + will appear on the host <-> BMC LPC bus. +Users: OpenBMC. Proposed changes should be mailed to + openbmc@lists.ozlabs.org + +What: /sys/bus/platform/drivers/aspeed-vuart*/sirq +Date: April 2017 +Contact: Jeremy Kerr <jk@ozlabs.org> +Description: Configures which interrupt number the host side of + the UART will appear on the host <-> BMC LPC bus. +Users: OpenBMC. Proposed changes should be mailed to + openbmc@lists.ozlabs.org diff --git a/Documentation/ABI/testing/configfs-usb-gadget-uac1 b/Documentation/ABI/testing/configfs-usb-gadget-uac1 index 8ba9a123316e..abfe447c848f 100644 --- a/Documentation/ABI/testing/configfs-usb-gadget-uac1 +++ b/Documentation/ABI/testing/configfs-usb-gadget-uac1 @@ -1,12 +1,14 @@ What: /config/usb-gadget/gadget/functions/uac1.name -Date: Sep 2014 -KernelVersion: 3.18 +Date: June 2017 +KernelVersion: 4.14 Description: The attributes: - audio_buf_size - audio buffer size - fn_cap - capture pcm device file name - fn_cntl - control device file name - fn_play - playback pcm device file name - req_buf_size - ISO OUT endpoint request buffer size - req_count - ISO OUT endpoint request count + c_chmask - capture channel mask + c_srate - capture sampling rate + c_ssize - capture sample size (bytes) + p_chmask - playback channel mask + p_srate - playback sampling rate + p_ssize - playback sample size (bytes) + req_number - the number of pre-allocated request + for both capture and playback diff --git a/Documentation/ABI/testing/configfs-usb-gadget-uac1_legacy b/Documentation/ABI/testing/configfs-usb-gadget-uac1_legacy new file mode 100644 index 000000000000..b2eaefd9bc49 --- /dev/null +++ b/Documentation/ABI/testing/configfs-usb-gadget-uac1_legacy @@ -0,0 +1,12 @@ +What: /config/usb-gadget/gadget/functions/uac1_legacy.name +Date: Sep 2014 +KernelVersion: 3.18 +Description: + The attributes: + + audio_buf_size - audio buffer size + fn_cap - capture pcm device file name + fn_cntl - control device file name + fn_play - playback pcm device file name + req_buf_size - ISO OUT endpoint request buffer size + req_count - ISO OUT endpoint request count diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index bb0f9a135e21..e76432b9954d 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -34,9 +34,10 @@ Description: fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6) uid:= decimal value euid:= decimal value - fowner:=decimal value + fowner:= decimal value lsm: are LSM specific option: appraise_type:= [imasig] + pcr:= decimal value default policy: # PROC_SUPER_MAGIC @@ -96,3 +97,8 @@ Description: Smack: measure subj_user=_ func=FILE_CHECK mask=MAY_READ + + Example of measure rules using alternate PCRs: + + measure func=KEXEC_KERNEL_CHECK pcr=4 + measure func=KEXEC_INITRAMFS_CHECK pcr=5 diff --git a/Documentation/ABI/testing/sysfs-bus-fsi b/Documentation/ABI/testing/sysfs-bus-fsi new file mode 100644 index 000000000000..57c806350d6c --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-fsi @@ -0,0 +1,38 @@ +What: /sys/bus/platform/devices/fsi-master/rescan +Date: May 2017 +KernelVersion: 4.12 +Contact: cbostic@linux.vnet.ibm.com +Description: + Initiates a FSI master scan for all connected slave devices + on its links. + +What: /sys/bus/platform/devices/fsi-master/break +Date: May 2017 +KernelVersion: 4.12 +Contact: cbostic@linux.vnet.ibm.com +Description: + Sends an FSI BREAK command on a master's communication + link to any connnected slaves. A BREAK resets connected + device's logic and preps it to receive further commands + from the master. + +What: /sys/bus/platform/devices/fsi-master/slave@00:00/term +Date: May 2017 +KernelVersion: 4.12 +Contact: cbostic@linux.vnet.ibm.com +Description: + Sends an FSI terminate command from the master to its + connected slave. A terminate resets the slave's state machines + that control access to the internally connected engines. In + addition the slave freezes its internal error register for + debugging purposes. This command is also needed to abort any + ongoing operation in case of an expired 'Master Time Out' + timer. + +What: /sys/bus/platform/devices/fsi-master/slave@00:00/raw +Date: May 2017 +KernelVersion: 4.12 +Contact: cbostic@linux.vnet.ibm.com +Description: + Provides a means of reading/writing a 32 bit value from/to a + specified FSI bus address. diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio index 8c24d0892f61..2db2cdf42d54 100644 --- a/Documentation/ABI/testing/sysfs-bus-iio +++ b/Documentation/ABI/testing/sysfs-bus-iio @@ -1425,6 +1425,17 @@ Description: guarantees that the hardware fifo is flushed to the device buffer. +What: /sys/bus/iio/devices/iio:device*/buffer/hwfifo_timeout +KernelVersion: 4.12 +Contact: linux-iio@vger.kernel.org +Description: + A read/write property to provide capability to delay reporting of + samples till a timeout is reached. This allows host processors to + sleep, while the sensor is storing samples in its internal fifo. + The maximum timeout in seconds can be specified by setting + hwfifo_timeout.The current delay can be read by reading + hwfifo_timeout. A value of 0 means that there is no timeout. + What: /sys/bus/iio/devices/iio:deviceX/buffer/hwfifo_watermark KernelVersion: 4.2 Contact: linux-iio@vger.kernel.org diff --git a/Documentation/ABI/testing/sysfs-bus-iio-meas-spec b/Documentation/ABI/testing/sysfs-bus-iio-meas-spec index 1a6265e92e2f..6d47e548eee5 100644 --- a/Documentation/ABI/testing/sysfs-bus-iio-meas-spec +++ b/Documentation/ABI/testing/sysfs-bus-iio-meas-spec @@ -5,4 +5,3 @@ Description: Reading returns either '1' or '0'. '1' means that the battery level supplied to sensor is below 2.25V. This ABI is available for tsys02d, htu21, ms8607 - This ABI is available for htu21, ms8607 diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 index 230020e06677..161c147d3c40 100644 --- a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 @@ -16,6 +16,54 @@ Description: - "OC2REF" : OC2REF signal is used as trigger output. - "OC3REF" : OC3REF signal is used as trigger output. - "OC4REF" : OC4REF signal is used as trigger output. + Additional modes (on TRGO2 only): + - "OC5REF" : OC5REF signal is used as trigger output. + - "OC6REF" : OC6REF signal is used as trigger output. + - "compare_pulse_OC4REF": + OC4REF rising or falling edges generate pulses. + - "compare_pulse_OC6REF": + OC6REF rising or falling edges generate pulses. + - "compare_pulse_OC4REF_r_or_OC6REF_r": + OC4REF or OC6REF rising edges generate pulses. + - "compare_pulse_OC4REF_r_or_OC6REF_f": + OC4REF rising or OC6REF falling edges generate pulses. + - "compare_pulse_OC5REF_r_or_OC6REF_r": + OC5REF or OC6REF rising edges generate pulses. + - "compare_pulse_OC5REF_r_or_OC6REF_f": + OC5REF rising or OC6REF falling edges generate pulses. + + +-----------+ +-------------+ +---------+ + | Prescaler +-> | Counter | +-> | Master | TRGO(2) + +-----------+ +--+--------+-+ |-> | Control +--> + | | || +---------+ + +--v--------+-+ OCxREF || +---------+ + | Chx compare +----------> | Output | ChX + +-----------+-+ | | Control +--> + . | | +---------+ + . | | . + +-----------v-+ OC6REF | . + | Ch6 compare +---------+> + +-------------+ + + Example with: "compare_pulse_OC4REF_r_or_OC6REF_r": + + X + X X + X . . X + X . . X + X . . X + count X . . . . X + . . . . + . . . . + +---------------+ + OC4REF | . . | + +-+ . . +-+ + . +---+ . + OC6REF . | | . + +-------+ +-------+ + +-+ +-+ + TRGO2 | | | | + +-+ +---+ +---------+ What: /sys/bus/iio/devices/triggerX/master_mode KernelVersion: 4.11 @@ -90,3 +138,18 @@ Description: Counting is enabled on rising edge of the connected trigger, and remains enabled for the duration of this selected mode. + +What: /sys/bus/iio/devices/iio:deviceX/in_count_trigger_mode_available +KernelVersion: 4.13 +Contact: benjamin.gaignard@st.com +Description: + Reading returns the list possible trigger modes. + +What: /sys/bus/iio/devices/iio:deviceX/in_count0_trigger_mode +KernelVersion: 4.13 +Contact: benjamin.gaignard@st.com +Description: + Configure the device counter trigger mode + counting direction is set by in_count0_count_direction + attribute and the counter is clocked by the connected trigger + rising edges. diff --git a/Documentation/ABI/testing/sysfs-bus-thunderbolt b/Documentation/ABI/testing/sysfs-bus-thunderbolt new file mode 100644 index 000000000000..2a98149943ea --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-thunderbolt @@ -0,0 +1,110 @@ +What: /sys/bus/thunderbolt/devices/.../domainX/security +Date: Sep 2017 +KernelVersion: 4.13 +Contact: thunderbolt-software@lists.01.org +Description: This attribute holds current Thunderbolt security level + set by the system BIOS. Possible values are: + + none: All devices are automatically authorized + user: Devices are only authorized based on writing + appropriate value to the authorized attribute + secure: Require devices that support secure connect at + minimum. User needs to authorize each device. + dponly: Automatically tunnel Display port (and USB). No + PCIe tunnels are created. + +What: /sys/bus/thunderbolt/devices/.../authorized +Date: Sep 2017 +KernelVersion: 4.13 +Contact: thunderbolt-software@lists.01.org +Description: This attribute is used to authorize Thunderbolt devices + after they have been connected. If the device is not + authorized, no devices such as PCIe and Display port are + available to the system. + + Contents of this attribute will be 0 when the device is not + yet authorized. + + Possible values are supported: + 1: The device will be authorized and connected + + When key attribute contains 32 byte hex string the possible + values are: + 1: The 32 byte hex string is added to the device NVM and + the device is authorized. + 2: Send a challenge based on the 32 byte hex string. If the + challenge response from device is valid, the device is + authorized. In case of failure errno will be ENOKEY if + the device did not contain a key at all, and + EKEYREJECTED if the challenge response did not match. + +What: /sys/bus/thunderbolt/devices/.../key +Date: Sep 2017 +KernelVersion: 4.13 +Contact: thunderbolt-software@lists.01.org +Description: When a devices supports Thunderbolt secure connect it will + have this attribute. Writing 32 byte hex string changes + authorization to use the secure connection method instead. + +What: /sys/bus/thunderbolt/devices/.../device +Date: Sep 2017 +KernelVersion: 4.13 +Contact: thunderbolt-software@lists.01.org +Description: This attribute contains id of this device extracted from + the device DROM. + +What: /sys/bus/thunderbolt/devices/.../device_name +Date: Sep 2017 +KernelVersion: 4.13 +Contact: thunderbolt-software@lists.01.org +Description: This attribute contains name of this device extracted from + the device DROM. + +What: /sys/bus/thunderbolt/devices/.../vendor +Date: Sep 2017 +KernelVersion: 4.13 +Contact: thunderbolt-software@lists.01.org +Description: This attribute contains vendor id of this device extracted + from the device DROM. + +What: /sys/bus/thunderbolt/devices/.../vendor_name +Date: Sep 2017 +KernelVersion: 4.13 +Contact: thunderbolt-software@lists.01.org +Description: This attribute contains vendor name of this device extracted + from the device DROM. + +What: /sys/bus/thunderbolt/devices/.../unique_id +Date: Sep 2017 +KernelVersion: 4.13 +Contact: thunderbolt-software@lists.01.org +Description: This attribute contains unique_id string of this device. + This is either read from hardware registers (UUID on + newer hardware) or based on UID from the device DROM. + Can be used to uniquely identify particular device. + +What: /sys/bus/thunderbolt/devices/.../nvm_version +Date: Sep 2017 +KernelVersion: 4.13 +Contact: thunderbolt-software@lists.01.org +Description: If the device has upgradeable firmware the version + number is available here. Format: %x.%x, major.minor. + If the device is in safe mode reading the file returns + -ENODATA instead as the NVM version is not available. + +What: /sys/bus/thunderbolt/devices/.../nvm_authenticate +Date: Sep 2017 +KernelVersion: 4.13 +Contact: thunderbolt-software@lists.01.org +Description: When new NVM image is written to the non-active NVM + area (through non_activeX NVMem device), the + authentication procedure is started by writing 1 to + this file. If everything goes well, the device is + restarted with the new NVM firmware. If the image + verification fails an error code is returned instead. + + When read holds status of the last authentication + operation if an error occurred during the process. This + is directly the status value from the DMA configuration + based mailbox before the device is power cycled. Writing + 0 here clears the status. diff --git a/Documentation/ABI/testing/sysfs-class-mux b/Documentation/ABI/testing/sysfs-class-mux new file mode 100644 index 000000000000..8715f9c7bd4f --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-mux @@ -0,0 +1,16 @@ +What: /sys/class/mux/ +Date: April 2017 +KernelVersion: 4.13 +Contact: Peter Rosin <peda@axentia.se> +Description: + The mux/ class sub-directory belongs to the Generic MUX + Framework and provides a sysfs interface for using MUX + controllers. + +What: /sys/class/mux/muxchipN/ +Date: April 2017 +KernelVersion: 4.13 +Contact: Peter Rosin <peda@axentia.se> +Description: + A /sys/class/mux/muxchipN directory is created for each + probed MUX chip where N is a simple enumeration. diff --git a/Documentation/ABI/testing/sysfs-class-net b/Documentation/ABI/testing/sysfs-class-net index 668604fc8e06..6856da99b6f7 100644 --- a/Documentation/ABI/testing/sysfs-class-net +++ b/Documentation/ABI/testing/sysfs-class-net @@ -251,3 +251,11 @@ Contact: netdev@vger.kernel.org Description: Indicates the unique physical switch identifier of a switch this port belongs to, as a string. + +What: /sys/class/net/<iface>/phydev +Date: May 2017 +KernelVersion: 4.13 +Contact: netdev@vger.kernel.org +Description: + Symbolic link to the PHY device this network device is attached + to. diff --git a/Documentation/ABI/testing/sysfs-class-net-phydev b/Documentation/ABI/testing/sysfs-class-net-phydev new file mode 100644 index 000000000000..6ebabfb27912 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-class-net-phydev @@ -0,0 +1,36 @@ +What: /sys/class/mdio_bus/<bus>/<device>/attached_dev +Date: May 2017 +KernelVersion: 4.13 +Contact: netdev@vger.kernel.org +Description: + Symbolic link to the network device this PHY device is + attached to. + +What: /sys/class/mdio_bus/<bus>/<device>/phy_has_fixups +Date: February 2014 +KernelVersion: 3.15 +Contact: netdev@vger.kernel.org +Description: + Boolean value indicating whether the PHY device has + any fixups registered against it (phy_register_fixup) + +What: /sys/class/mdio_bus/<bus>/<device>/phy_id +Date: November 2012 +KernelVersion: 3.8 +Contact: netdev@vger.kernel.org +Description: + 32-bit hexadecimal value corresponding to the PHY device's OUI, + model and revision number. + +What: /sys/class/mdio_bus/<bus>/<device>/phy_interface +Date: February 2014 +KernelVersion: 3.15 +Contact: netdev@vger.kernel.org +Description: + String value indicating the PHY interface, possible + values are:. + <empty> (not available), mii, gmii, sgmii, tbi, rev-mii, + rmii, rgmii, rgmii-id, rgmii-rxid, rgmii-txid, rtbi, smii + xgmii, moca, qsgmii, trgmii, 1000base-x, 2500base-x, rxaui, + xaui, 10gbase-kr, unknown + diff --git a/Documentation/ABI/testing/sysfs-class-power-twl4030 b/Documentation/ABI/testing/sysfs-class-power-twl4030 index be26af0f1895..b4fd32d210c5 100644 --- a/Documentation/ABI/testing/sysfs-class-power-twl4030 +++ b/Documentation/ABI/testing/sysfs-class-power-twl4030 @@ -1,20 +1,3 @@ -What: /sys/class/power_supply/twl4030_ac/max_current - /sys/class/power_supply/twl4030_usb/max_current -Description: - Read/Write limit on current which may - be drawn from the ac (Accessory Charger) or - USB port. - - Value is in micro-Amps. - - Value is set automatically to an appropriate - value when a cable is plugged or unplugged. - - Value can the set by writing to the attribute. - The change will only persist until the next - plug event. These event are reported via udev. - - What: /sys/class/power_supply/twl4030_usb/mode Description: Changing mode for USB port. diff --git a/Documentation/ABI/testing/sysfs-class-typec b/Documentation/ABI/testing/sysfs-class-typec index d4a3d23eb09c..5be552e255e9 100644 --- a/Documentation/ABI/testing/sysfs-class-typec +++ b/Documentation/ABI/testing/sysfs-class-typec @@ -30,6 +30,21 @@ Description: Valid values: source, sink +What: /sys/class/typec/<port>/port_type +Date: May 2017 +Contact: Badhri Jagan Sridharan <Badhri@google.com> +Description: + Indicates the type of the port. This attribute can be used for + requesting a change in the port type. Port type change is + supported as a synchronous operation, so write(2) to the + attribute will not return until the operation has finished. + + Valid values: + - source (The port will behave as source only DFP port) + - sink (The port will behave as sink only UFP port) + - dual (The port will behave as dual-role-data and + dual-role-power port) + What: /sys/class/typec/<port>/vconn_source Date: April 2017 Contact: Heikki Krogerus <heikki.krogerus@linux.intel.com> diff --git a/Documentation/ABI/testing/sysfs-uevent b/Documentation/ABI/testing/sysfs-uevent new file mode 100644 index 000000000000..aa39f8d7bcdf --- /dev/null +++ b/Documentation/ABI/testing/sysfs-uevent @@ -0,0 +1,47 @@ +What: /sys/.../uevent +Date: May 2017 +KernelVersion: 4.13 +Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> +Description: + Enable passing additional variables for synthetic uevents that + are generated by writing /sys/.../uevent file. + + Recognized extended format is ACTION [UUID [KEY=VALUE ...]. + + The ACTION is compulsory - it is the name of the uevent action + ("add", "change", "remove"). There is no change compared to + previous functionality here. The rest of the extended format + is optional. + + You need to pass UUID first before any KEY=VALUE pairs. + The UUID must be in "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" + format where 'x' is a hex digit. The UUID is considered to be + a transaction identifier so it's possible to use the same UUID + value for one or more synthetic uevents in which case we + logically group these uevents together for any userspace + listeners. The UUID value appears in uevent as + "SYNTH_UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" environment + variable. + + If UUID is not passed in, the generated synthetic uevent gains + "SYNTH_UUID=0" environment variable automatically. + + The KEY=VALUE pairs can contain alphanumeric characters only. + It's possible to define zero or more pairs - each pair is then + delimited by a space character ' '. Each pair appears in + synthetic uevent as "SYNTH_ARG_KEY=VALUE". That means the KEY + name gains "SYNTH_ARG_" prefix to avoid possible collisions + with existing variables. + + Example of valid sequence written to the uevent file: + + add fe4d7c9d-b8c6-4a70-9ef1-3d8a58d18eed A=1 B=abc + + This generates synthetic uevent including these variables: + + ACTION=add + SYNTH_ARG_A=1 + SYNTH_ARG_B=abc + SYNTH_UUID=fe4d7c9d-b8c6-4a70-9ef1-3d8a58d18eed +Users: + udev, userspace tools generating synthetic uevents diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt index 6b20128fab8a..71200dfa0922 100644 --- a/Documentation/DMA-API.txt +++ b/Documentation/DMA-API.txt @@ -692,7 +692,7 @@ of preallocated entries is defined per architecture. If it is too low for you boot with 'dma_debug_entries=<your_desired_number>' to overwrite the architectural default. -void debug_dmap_mapping_error(struct device *dev, dma_addr_t dma_addr); +void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr); dma-debug interface debug_dma_mapping_error() to debug drivers that fail to check DMA mapping errors on addresses returned by dma_map_single() and diff --git a/Documentation/DocBook/.gitignore b/Documentation/DocBook/.gitignore deleted file mode 100644 index e05da3f7aa21..000000000000 --- a/Documentation/DocBook/.gitignore +++ /dev/null @@ -1,17 +0,0 @@ -*.xml -*.ps -*.pdf -*.html -*.9.gz -*.9 -*.aux -*.dvi -*.log -*.out -*.png -*.gif -*.svg -*.proc -*.db -media-indices.tmpl -media-entities.tmpl diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile deleted file mode 100644 index 85916f13d330..000000000000 --- a/Documentation/DocBook/Makefile +++ /dev/null @@ -1,282 +0,0 @@ -### -# This makefile is used to generate the kernel documentation, -# primarily based on in-line comments in various source files. -# See Documentation/kernel-doc-nano-HOWTO.txt for instruction in how -# to document the SRC - and how to read it. -# To add a new book the only step required is to add the book to the -# list of DOCBOOKS. - -DOCBOOKS := z8530book.xml \ - kernel-hacking.xml kernel-locking.xml \ - networking.xml \ - filesystems.xml lsm.xml kgdb.xml \ - libata.xml mtdnand.xml librs.xml rapidio.xml \ - s390-drivers.xml scsi.xml \ - sh.xml w1.xml - -ifeq ($(DOCBOOKS),) - -# Skip DocBook build if the user explicitly requested no DOCBOOKS. -.DEFAULT: - @echo " SKIP DocBook $@ target (DOCBOOKS=\"\" specified)." -else -ifneq ($(SPHINXDIRS),) - -# Skip DocBook build if the user explicitly requested a sphinx dir -.DEFAULT: - @echo " SKIP DocBook $@ target (SPHINXDIRS specified)." -else - - -### -# The build process is as follows (targets): -# (xmldocs) [by docproc] -# file.tmpl --> file.xml +--> file.ps (psdocs) [by db2ps or xmlto] -# +--> file.pdf (pdfdocs) [by db2pdf or xmlto] -# +--> DIR=file (htmldocs) [by xmlto] -# +--> man/ (mandocs) [by xmlto] - - -# for PDF and PS output you can choose between xmlto and docbook-utils tools -PDF_METHOD = $(prefer-db2x) -PS_METHOD = $(prefer-db2x) - - -targets += $(DOCBOOKS) -BOOKS := $(addprefix $(obj)/,$(DOCBOOKS)) -xmldocs: $(BOOKS) -sgmldocs: xmldocs - -PS := $(patsubst %.xml, %.ps, $(BOOKS)) -psdocs: $(PS) - -PDF := $(patsubst %.xml, %.pdf, $(BOOKS)) -pdfdocs: $(PDF) - -HTML := $(sort $(patsubst %.xml, %.html, $(BOOKS))) -htmldocs: $(HTML) - $(call cmd,build_main_index) - -MAN := $(patsubst %.xml, %.9, $(BOOKS)) -mandocs: $(MAN) - find $(obj)/man -name '*.9' | xargs gzip -nf - -# Default location for installed man pages -export INSTALL_MAN_PATH = $(objtree)/usr - -installmandocs: mandocs - mkdir -p $(INSTALL_MAN_PATH)/man/man9/ - find $(obj)/man -name '*.9.gz' -printf '%h %f\n' | \ - sort -k 2 -k 1 | uniq -f 1 | sed -e 's: :/:' | \ - xargs install -m 644 -t $(INSTALL_MAN_PATH)/man/man9/ - -# no-op for the DocBook toolchain -epubdocs: -latexdocs: -linkcheckdocs: - -### -#External programs used -KERNELDOCXMLREF = $(srctree)/scripts/kernel-doc-xml-ref -KERNELDOC = $(srctree)/scripts/kernel-doc -DOCPROC = $(objtree)/scripts/docproc -CHECK_LC_CTYPE = $(objtree)/scripts/check-lc_ctype - -# Use a fixed encoding - UTF-8 if the C library has support built-in -# or ASCII if not -LC_CTYPE := $(call try-run, LC_CTYPE=C.UTF-8 $(CHECK_LC_CTYPE),C.UTF-8,C) -export LC_CTYPE - -XMLTOFLAGS = -m $(srctree)/$(src)/stylesheet.xsl -XMLTOFLAGS += --skip-validation - -### -# DOCPROC is used for two purposes: -# 1) To generate a dependency list for a .tmpl file -# 2) To preprocess a .tmpl file and call kernel-doc with -# appropriate parameters. -# The following rules are used to generate the .xml documentation -# required to generate the final targets. (ps, pdf, html). -quiet_cmd_docproc = DOCPROC $@ - cmd_docproc = SRCTREE=$(srctree)/ $(DOCPROC) doc $< >$@ -define rule_docproc - set -e; \ - $(if $($(quiet)cmd_$(1)),echo ' $($(quiet)cmd_$(1))';) \ - $(cmd_$(1)); \ - ( \ - echo 'cmd_$@ := $(cmd_$(1))'; \ - echo $@: `SRCTREE=$(srctree) $(DOCPROC) depend $<`; \ - ) > $(dir $@).$(notdir $@).cmd -endef - -%.xml: %.tmpl $(KERNELDOC) $(DOCPROC) $(KERNELDOCXMLREF) FORCE - $(call if_changed_rule,docproc) - -# Tell kbuild to always build the programs -always := $(hostprogs-y) - -notfoundtemplate = echo "*** You have to install docbook-utils or xmlto ***"; \ - exit 1 -db2xtemplate = db2TYPE -o $(dir $@) $< -xmltotemplate = xmlto TYPE $(XMLTOFLAGS) -o $(dir $@) $< - -# determine which methods are available -ifeq ($(shell which db2ps >/dev/null 2>&1 && echo found),found) - use-db2x = db2x - prefer-db2x = db2x -else - use-db2x = notfound - prefer-db2x = $(use-xmlto) -endif -ifeq ($(shell which xmlto >/dev/null 2>&1 && echo found),found) - use-xmlto = xmlto - prefer-xmlto = xmlto -else - use-xmlto = notfound - prefer-xmlto = $(use-db2x) -endif - -# the commands, generated from the chosen template -quiet_cmd_db2ps = PS $@ - cmd_db2ps = $(subst TYPE,ps, $($(PS_METHOD)template)) -%.ps : %.xml - $(call cmd,db2ps) - -quiet_cmd_db2pdf = PDF $@ - cmd_db2pdf = $(subst TYPE,pdf, $($(PDF_METHOD)template)) -%.pdf : %.xml - $(call cmd,db2pdf) - - -index = index.html -main_idx = $(obj)/$(index) -quiet_cmd_build_main_index = HTML $(main_idx) - cmd_build_main_index = rm -rf $(main_idx); \ - echo '<h1>Linux Kernel HTML Documentation</h1>' >> $(main_idx) && \ - echo '<h2>Kernel Version: $(KERNELVERSION)</h2>' >> $(main_idx) && \ - cat $(HTML) >> $(main_idx) - -quiet_cmd_db2html = HTML $@ - cmd_db2html = xmlto html $(XMLTOFLAGS) -o $(patsubst %.html,%,$@) $< && \ - echo '<a HREF="$(patsubst %.html,%,$(notdir $@))/index.html"> \ - $(patsubst %.html,%,$(notdir $@))</a><p>' > $@ - -### -# Rules to create an aux XML and .db, and use them to re-process the DocBook XML -# to fill internal hyperlinks - gen_aux_xml = : - quiet_gen_aux_xml = echo ' XMLREF $@' -silent_gen_aux_xml = : -%.aux.xml: %.xml - @$($(quiet)gen_aux_xml) - @rm -rf $@ - @(cat $< | egrep "^<refentry id" | egrep -o "\".*\"" | cut -f 2 -d \" > $<.db) - @$(KERNELDOCXMLREF) -db $<.db $< > $@ -.PRECIOUS: %.aux.xml - -%.html: %.aux.xml - @(which xmlto > /dev/null 2>&1) || \ - (echo "*** You need to install xmlto ***"; \ - exit 1) - @rm -rf $@ $(patsubst %.html,%,$@) - $(call cmd,db2html) - @if [ ! -z "$(PNG-$(basename $(notdir $@)))" ]; then \ - cp $(PNG-$(basename $(notdir $@))) $(patsubst %.html,%,$@); fi - -quiet_cmd_db2man = MAN $@ - cmd_db2man = if grep -q refentry $<; then xmlto man $(XMLTOFLAGS) -o $(obj)/man/$(*F) $< ; fi -%.9 : %.xml - @(which xmlto > /dev/null 2>&1) || \ - (echo "*** You need to install xmlto ***"; \ - exit 1) - $(Q)mkdir -p $(obj)/man/$(*F) - $(call cmd,db2man) - @touch $@ - -### -# Rules to generate postscripts and PNG images from .fig format files -quiet_cmd_fig2eps = FIG2EPS $@ - cmd_fig2eps = fig2dev -Leps $< $@ - -%.eps: %.fig - @(which fig2dev > /dev/null 2>&1) || \ - (echo "*** You need to install transfig ***"; \ - exit 1) - $(call cmd,fig2eps) - -quiet_cmd_fig2png = FIG2PNG $@ - cmd_fig2png = fig2dev -Lpng $< $@ - -%.png: %.fig - @(which fig2dev > /dev/null 2>&1) || \ - (echo "*** You need to install transfig ***"; \ - exit 1) - $(call cmd,fig2png) - -### -# Rule to convert a .c file to inline XML documentation - gen_xml = : - quiet_gen_xml = echo ' GEN $@' -silent_gen_xml = : -%.xml: %.c - @$($(quiet)gen_xml) - @( \ - echo "<programlisting>"; \ - expand --tabs=8 < $< | \ - sed -e "s/&/\\&/g" \ - -e "s/</\\</g" \ - -e "s/>/\\>/g"; \ - echo "</programlisting>") > $@ - -endif # DOCBOOKS="" -endif # SPHINDIR=... - -### -# Help targets as used by the top-level makefile -dochelp: - @echo ' Linux kernel internal documentation in different formats (DocBook):' - @echo ' htmldocs - HTML' - @echo ' pdfdocs - PDF' - @echo ' psdocs - Postscript' - @echo ' xmldocs - XML DocBook' - @echo ' mandocs - man pages' - @echo ' installmandocs - install man pages generated by mandocs to INSTALL_MAN_PATH'; \ - echo ' (default: $(INSTALL_MAN_PATH))'; \ - echo '' - @echo ' cleandocs - clean all generated DocBook files' - @echo - @echo ' make DOCBOOKS="s1.xml s2.xml" [target] Generate only docs s1.xml s2.xml' - @echo ' valid values for DOCBOOKS are: $(DOCBOOKS)' - @echo - @echo " make DOCBOOKS=\"\" [target] Don't generate docs from Docbook" - @echo ' This is useful to generate only the ReST docs (Sphinx)' - - -### -# Temporary files left by various tools -clean-files := $(DOCBOOKS) \ - $(patsubst %.xml, %.dvi, $(DOCBOOKS)) \ - $(patsubst %.xml, %.aux, $(DOCBOOKS)) \ - $(patsubst %.xml, %.tex, $(DOCBOOKS)) \ - $(patsubst %.xml, %.log, $(DOCBOOKS)) \ - $(patsubst %.xml, %.out, $(DOCBOOKS)) \ - $(patsubst %.xml, %.ps, $(DOCBOOKS)) \ - $(patsubst %.xml, %.pdf, $(DOCBOOKS)) \ - $(patsubst %.xml, %.html, $(DOCBOOKS)) \ - $(patsubst %.xml, %.9, $(DOCBOOKS)) \ - $(patsubst %.xml, %.aux.xml, $(DOCBOOKS)) \ - $(patsubst %.xml, %.xml.db, $(DOCBOOKS)) \ - $(patsubst %.xml, %.xml, $(DOCBOOKS)) \ - $(patsubst %.xml, .%.xml.cmd, $(DOCBOOKS)) \ - $(index) - -clean-dirs := $(patsubst %.xml,%,$(DOCBOOKS)) man - -cleandocs: - $(Q)rm -f $(call objectify, $(clean-files)) - $(Q)rm -rf $(call objectify, $(clean-dirs)) - -# Declare the contents of the .PHONY variable as phony. We keep that -# information in a variable so we can use it in if_changed and friends. - -.PHONY: $(PHONY) diff --git a/Documentation/DocBook/filesystems.tmpl b/Documentation/DocBook/filesystems.tmpl deleted file mode 100644 index 6006b6358c86..000000000000 --- a/Documentation/DocBook/filesystems.tmpl +++ /dev/null @@ -1,381 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="Linux-filesystems-API"> - <bookinfo> - <title>Linux Filesystems API</title> - - <legalnotice> - <para> - This documentation is free software; you can redistribute - it and/or modify it under the terms of the GNU General Public - License as published by the Free Software Foundation; either - version 2 of the License, or (at your option) any later - version. - </para> - - <para> - This program is distributed in the hope that it will be - useful, but WITHOUT ANY WARRANTY; without even the implied - warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. - See the GNU General Public License for more details. - </para> - - <para> - You should have received a copy of the GNU General Public - License along with this program; if not, write to the Free - Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, - MA 02111-1307 USA - </para> - - <para> - For more details see the file COPYING in the source - distribution of Linux. - </para> - </legalnotice> - </bookinfo> - -<toc></toc> - - <chapter id="vfs"> - <title>The Linux VFS</title> - <sect1 id="the_filesystem_types"><title>The Filesystem types</title> -!Iinclude/linux/fs.h - </sect1> - <sect1 id="the_directory_cache"><title>The Directory Cache</title> -!Efs/dcache.c -!Iinclude/linux/dcache.h - </sect1> - <sect1 id="inode_handling"><title>Inode Handling</title> -!Efs/inode.c -!Efs/bad_inode.c - </sect1> - <sect1 id="registration_and_superblocks"><title>Registration and Superblocks</title> -!Efs/super.c - </sect1> - <sect1 id="file_locks"><title>File Locks</title> -!Efs/locks.c -!Ifs/locks.c - </sect1> - <sect1 id="other_functions"><title>Other Functions</title> -!Efs/mpage.c -!Efs/namei.c -!Efs/buffer.c -!Eblock/bio.c -!Efs/seq_file.c -!Efs/filesystems.c -!Efs/fs-writeback.c -!Efs/block_dev.c - </sect1> - </chapter> - - <chapter id="proc"> - <title>The proc filesystem</title> - - <sect1 id="sysctl_interface"><title>sysctl interface</title> -!Ekernel/sysctl.c - </sect1> - - <sect1 id="proc_filesystem_interface"><title>proc filesystem interface</title> -!Ifs/proc/base.c - </sect1> - </chapter> - - <chapter id="fs_events"> - <title>Events based on file descriptors</title> -!Efs/eventfd.c - </chapter> - - <chapter id="sysfs"> - <title>The Filesystem for Exporting Kernel Objects</title> -!Efs/sysfs/file.c -!Efs/sysfs/symlink.c - </chapter> - - <chapter id="debugfs"> - <title>The debugfs filesystem</title> - - <sect1 id="debugfs_interface"><title>debugfs interface</title> -!Efs/debugfs/inode.c -!Efs/debugfs/file.c - </sect1> - </chapter> - - <chapter id="LinuxJDBAPI"> - <chapterinfo> - <title>The Linux Journalling API</title> - - <authorgroup> - <author> - <firstname>Roger</firstname> - <surname>Gammans</surname> - <affiliation> - <address> - <email>rgammans@computer-surgery.co.uk</email> - </address> - </affiliation> - </author> - </authorgroup> - - <authorgroup> - <author> - <firstname>Stephen</firstname> - <surname>Tweedie</surname> - <affiliation> - <address> - <email>sct@redhat.com</email> - </address> - </affiliation> - </author> - </authorgroup> - - <copyright> - <year>2002</year> - <holder>Roger Gammans</holder> - </copyright> - </chapterinfo> - - <title>The Linux Journalling API</title> - - <sect1 id="journaling_overview"> - <title>Overview</title> - <sect2 id="journaling_details"> - <title>Details</title> -<para> -The journalling layer is easy to use. You need to -first of all create a journal_t data structure. There are -two calls to do this dependent on how you decide to allocate the physical -media on which the journal resides. The jbd2_journal_init_inode() call -is for journals stored in filesystem inodes, or the jbd2_journal_init_dev() -call can be used for journal stored on a raw device (in a continuous range -of blocks). A journal_t is a typedef for a struct pointer, so when -you are finally finished make sure you call jbd2_journal_destroy() on it -to free up any used kernel memory. -</para> - -<para> -Once you have got your journal_t object you need to 'mount' or load the journal -file. The journalling layer expects the space for the journal was already -allocated and initialized properly by the userspace tools. When loading the -journal you must call jbd2_journal_load() to process journal contents. If the -client file system detects the journal contents does not need to be processed -(or even need not have valid contents), it may call jbd2_journal_wipe() to -clear the journal contents before calling jbd2_journal_load(). -</para> - -<para> -Note that jbd2_journal_wipe(..,0) calls jbd2_journal_skip_recovery() for you if -it detects any outstanding transactions in the journal and similarly -jbd2_journal_load() will call jbd2_journal_recover() if necessary. I would -advise reading ext4_load_journal() in fs/ext4/super.c for examples on this -stage. -</para> - -<para> -Now you can go ahead and start modifying the underlying -filesystem. Almost. -</para> - -<para> - -You still need to actually journal your filesystem changes, this -is done by wrapping them into transactions. Additionally you -also need to wrap the modification of each of the buffers -with calls to the journal layer, so it knows what the modifications -you are actually making are. To do this use jbd2_journal_start() which -returns a transaction handle. -</para> - -<para> -jbd2_journal_start() -and its counterpart jbd2_journal_stop(), which indicates the end of a -transaction are nestable calls, so you can reenter a transaction if necessary, -but remember you must call jbd2_journal_stop() the same number of times as -jbd2_journal_start() before the transaction is completed (or more accurately -leaves the update phase). Ext4/VFS makes use of this feature to simplify -handling of inode dirtying, quota support, etc. -</para> - -<para> -Inside each transaction you need to wrap the modifications to the -individual buffers (blocks). Before you start to modify a buffer you -need to call jbd2_journal_get_{create,write,undo}_access() as appropriate, -this allows the journalling layer to copy the unmodified data if it -needs to. After all the buffer may be part of a previously uncommitted -transaction. -At this point you are at last ready to modify a buffer, and once -you are have done so you need to call jbd2_journal_dirty_{meta,}data(). -Or if you've asked for access to a buffer you now know is now longer -required to be pushed back on the device you can call jbd2_journal_forget() -in much the same way as you might have used bforget() in the past. -</para> - -<para> -A jbd2_journal_flush() may be called at any time to commit and checkpoint -all your transactions. -</para> - -<para> -Then at umount time , in your put_super() you can then call jbd2_journal_destroy() -to clean up your in-core journal object. -</para> - -<para> -Unfortunately there a couple of ways the journal layer can cause a deadlock. -The first thing to note is that each task can only have -a single outstanding transaction at any one time, remember nothing -commits until the outermost jbd2_journal_stop(). This means -you must complete the transaction at the end of each file/inode/address -etc. operation you perform, so that the journalling system isn't re-entered -on another journal. Since transactions can't be nested/batched -across differing journals, and another filesystem other than -yours (say ext4) may be modified in a later syscall. -</para> - -<para> -The second case to bear in mind is that jbd2_journal_start() can -block if there isn't enough space in the journal for your transaction -(based on the passed nblocks param) - when it blocks it merely(!) needs to -wait for transactions to complete and be committed from other tasks, -so essentially we are waiting for jbd2_journal_stop(). So to avoid -deadlocks you must treat jbd2_journal_start/stop() as if they -were semaphores and include them in your semaphore ordering rules to prevent -deadlocks. Note that jbd2_journal_extend() has similar blocking behaviour to -jbd2_journal_start() so you can deadlock here just as easily as on -jbd2_journal_start(). -</para> - -<para> -Try to reserve the right number of blocks the first time. ;-). This will -be the maximum number of blocks you are going to touch in this transaction. -I advise having a look at at least ext4_jbd.h to see the basis on which -ext4 uses to make these decisions. -</para> - -<para> -Another wriggle to watch out for is your on-disk block allocation strategy. -Why? Because, if you do a delete, you need to ensure you haven't reused any -of the freed blocks until the transaction freeing these blocks commits. If you -reused these blocks and crash happens, there is no way to restore the contents -of the reallocated blocks at the end of the last fully committed transaction. - -One simple way of doing this is to mark blocks as free in internal in-memory -block allocation structures only after the transaction freeing them commits. -Ext4 uses journal commit callback for this purpose. -</para> - -<para> -With journal commit callbacks you can ask the journalling layer to call a -callback function when the transaction is finally committed to disk, so that -you can do some of your own management. You ask the journalling layer for -calling the callback by simply setting journal->j_commit_callback function -pointer and that function is called after each transaction commit. You can also -use transaction->t_private_list for attaching entries to a transaction that -need processing when the transaction commits. -</para> - -<para> -JBD2 also provides a way to block all transaction updates via -jbd2_journal_{un,}lock_updates(). Ext4 uses this when it wants a window with a -clean and stable fs for a moment. E.g. -</para> - -<programlisting> - - jbd2_journal_lock_updates() //stop new stuff happening.. - jbd2_journal_flush() // checkpoint everything. - ..do stuff on stable fs - jbd2_journal_unlock_updates() // carry on with filesystem use. -</programlisting> - -<para> -The opportunities for abuse and DOS attacks with this should be obvious, -if you allow unprivileged userspace to trigger codepaths containing these -calls. -</para> - - </sect2> - - <sect2 id="jbd_summary"> - <title>Summary</title> -<para> -Using the journal is a matter of wrapping the different context changes, -being each mount, each modification (transaction) and each changed buffer -to tell the journalling layer about them. -</para> - - </sect2> - - </sect1> - - <sect1 id="data_types"> - <title>Data Types</title> - <para> - The journalling layer uses typedefs to 'hide' the concrete definitions - of the structures used. As a client of the JBD2 layer you can - just rely on the using the pointer as a magic cookie of some sort. - - Obviously the hiding is not enforced as this is 'C'. - </para> - <sect2 id="structures"><title>Structures</title> -!Iinclude/linux/jbd2.h - </sect2> - </sect1> - - <sect1 id="functions"> - <title>Functions</title> - <para> - The functions here are split into two groups those that - affect a journal as a whole, and those which are used to - manage transactions - </para> - <sect2 id="journal_level"><title>Journal Level</title> -!Efs/jbd2/journal.c -!Ifs/jbd2/recovery.c - </sect2> - <sect2 id="transaction_level"><title>Transasction Level</title> -!Efs/jbd2/transaction.c - </sect2> - </sect1> - <sect1 id="see_also"> - <title>See also</title> - <para> - <citation> - <ulink url="http://kernel.org/pub/linux/kernel/people/sct/ext3/journal-design.ps.gz"> - Journaling the Linux ext2fs Filesystem, LinuxExpo 98, Stephen Tweedie - </ulink> - </citation> - </para> - <para> - <citation> - <ulink url="http://olstrans.sourceforge.net/release/OLS2000-ext3/OLS2000-ext3.html"> - Ext3 Journalling FileSystem, OLS 2000, Dr. Stephen Tweedie - </ulink> - </citation> - </para> - </sect1> - - </chapter> - - <chapter id="splice"> - <title>splice API</title> - <para> - splice is a method for moving blocks of data around inside the - kernel, without continually transferring them between the kernel - and user space. - </para> -!Ffs/splice.c - </chapter> - - <chapter id="pipes"> - <title>pipes API</title> - <para> - Pipe interfaces are all for in-kernel (builtin image) use. - They are not exported for use by modules. - </para> -!Iinclude/linux/pipe_fs_i.h -!Ffs/pipe.c - </chapter> - -</book> diff --git a/Documentation/DocBook/kernel-hacking.tmpl b/Documentation/DocBook/kernel-hacking.tmpl deleted file mode 100644 index da5c087462b1..000000000000 --- a/Documentation/DocBook/kernel-hacking.tmpl +++ /dev/null @@ -1,1312 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="lk-hacking-guide"> - <bookinfo> - <title>Unreliable Guide To Hacking The Linux Kernel</title> - - <authorgroup> - <author> - <firstname>Rusty</firstname> - <surname>Russell</surname> - <affiliation> - <address> - <email>rusty@rustcorp.com.au</email> - </address> - </affiliation> - </author> - </authorgroup> - - <copyright> - <year>2005</year> - <holder>Rusty Russell</holder> - </copyright> - - <legalnotice> - <para> - This documentation is free software; you can redistribute - it and/or modify it under the terms of the GNU General Public - License as published by the Free Software Foundation; either - version 2 of the License, or (at your option) any later - version. - </para> - - <para> - This program is distributed in the hope that it will be - useful, but WITHOUT ANY WARRANTY; without even the implied - warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. - See the GNU General Public License for more details. - </para> - - <para> - You should have received a copy of the GNU General Public - License along with this program; if not, write to the Free - Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, - MA 02111-1307 USA - </para> - - <para> - For more details see the file COPYING in the source - distribution of Linux. - </para> - </legalnotice> - - <releaseinfo> - This is the first release of this document as part of the kernel tarball. - </releaseinfo> - - </bookinfo> - - <toc></toc> - - <chapter id="introduction"> - <title>Introduction</title> - <para> - Welcome, gentle reader, to Rusty's Remarkably Unreliable Guide to Linux - Kernel Hacking. This document describes the common routines and - general requirements for kernel code: its goal is to serve as a - primer for Linux kernel development for experienced C - programmers. I avoid implementation details: that's what the - code is for, and I ignore whole tracts of useful routines. - </para> - <para> - Before you read this, please understand that I never wanted to - write this document, being grossly under-qualified, but I always - wanted to read it, and this was the only way. I hope it will - grow into a compendium of best practice, common starting points - and random information. - </para> - </chapter> - - <chapter id="basic-players"> - <title>The Players</title> - - <para> - At any time each of the CPUs in a system can be: - </para> - - <itemizedlist> - <listitem> - <para> - not associated with any process, serving a hardware interrupt; - </para> - </listitem> - - <listitem> - <para> - not associated with any process, serving a softirq or tasklet; - </para> - </listitem> - - <listitem> - <para> - running in kernel space, associated with a process (user context); - </para> - </listitem> - - <listitem> - <para> - running a process in user space. - </para> - </listitem> - </itemizedlist> - - <para> - There is an ordering between these. The bottom two can preempt - each other, but above that is a strict hierarchy: each can only be - preempted by the ones above it. For example, while a softirq is - running on a CPU, no other softirq will preempt it, but a hardware - interrupt can. However, any other CPUs in the system execute - independently. - </para> - - <para> - We'll see a number of ways that the user context can block - interrupts, to become truly non-preemptable. - </para> - - <sect1 id="basics-usercontext"> - <title>User Context</title> - - <para> - User context is when you are coming in from a system call or other - trap: like userspace, you can be preempted by more important tasks - and by interrupts. You can sleep, by calling - <function>schedule()</function>. - </para> - - <note> - <para> - You are always in user context on module load and unload, - and on operations on the block device layer. - </para> - </note> - - <para> - In user context, the <varname>current</varname> pointer (indicating - the task we are currently executing) is valid, and - <function>in_interrupt()</function> - (<filename>include/linux/interrupt.h</filename>) is <returnvalue>false - </returnvalue>. - </para> - - <caution> - <para> - Beware that if you have preemption or softirqs disabled - (see below), <function>in_interrupt()</function> will return a - false positive. - </para> - </caution> - </sect1> - - <sect1 id="basics-hardirqs"> - <title>Hardware Interrupts (Hard IRQs)</title> - - <para> - Timer ticks, <hardware>network cards</hardware> and - <hardware>keyboard</hardware> are examples of real - hardware which produce interrupts at any time. The kernel runs - interrupt handlers, which services the hardware. The kernel - guarantees that this handler is never re-entered: if the same - interrupt arrives, it is queued (or dropped). Because it - disables interrupts, this handler has to be fast: frequently it - simply acknowledges the interrupt, marks a 'software interrupt' - for execution and exits. - </para> - - <para> - You can tell you are in a hardware interrupt, because - <function>in_irq()</function> returns <returnvalue>true</returnvalue>. - </para> - <caution> - <para> - Beware that this will return a false positive if interrupts are disabled - (see below). - </para> - </caution> - </sect1> - - <sect1 id="basics-softirqs"> - <title>Software Interrupt Context: Softirqs and Tasklets</title> - - <para> - Whenever a system call is about to return to userspace, or a - hardware interrupt handler exits, any 'software interrupts' - which are marked pending (usually by hardware interrupts) are - run (<filename>kernel/softirq.c</filename>). - </para> - - <para> - Much of the real interrupt handling work is done here. Early in - the transition to <acronym>SMP</acronym>, there were only 'bottom - halves' (BHs), which didn't take advantage of multiple CPUs. Shortly - after we switched from wind-up computers made of match-sticks and snot, - we abandoned this limitation and switched to 'softirqs'. - </para> - - <para> - <filename class="headerfile">include/linux/interrupt.h</filename> lists the - different softirqs. A very important softirq is the - timer softirq (<filename - class="headerfile">include/linux/timer.h</filename>): you can - register to have it call functions for you in a given length of - time. - </para> - - <para> - Softirqs are often a pain to deal with, since the same softirq - will run simultaneously on more than one CPU. For this reason, - tasklets (<filename - class="headerfile">include/linux/interrupt.h</filename>) are more - often used: they are dynamically-registrable (meaning you can have - as many as you want), and they also guarantee that any tasklet - will only run on one CPU at any time, although different tasklets - can run simultaneously. - </para> - <caution> - <para> - The name 'tasklet' is misleading: they have nothing to do with 'tasks', - and probably more to do with some bad vodka Alexey Kuznetsov had at the - time. - </para> - </caution> - - <para> - You can tell you are in a softirq (or tasklet) - using the <function>in_softirq()</function> macro - (<filename class="headerfile">include/linux/interrupt.h</filename>). - </para> - <caution> - <para> - Beware that this will return a false positive if a bh lock (see below) - is held. - </para> - </caution> - </sect1> - </chapter> - - <chapter id="basic-rules"> - <title>Some Basic Rules</title> - - <variablelist> - <varlistentry> - <term>No memory protection</term> - <listitem> - <para> - If you corrupt memory, whether in user context or - interrupt context, the whole machine will crash. Are you - sure you can't do what you want in userspace? - </para> - </listitem> - </varlistentry> - - <varlistentry> - <term>No floating point or <acronym>MMX</acronym></term> - <listitem> - <para> - The <acronym>FPU</acronym> context is not saved; even in user - context the <acronym>FPU</acronym> state probably won't - correspond with the current process: you would mess with some - user process' <acronym>FPU</acronym> state. If you really want - to do this, you would have to explicitly save/restore the full - <acronym>FPU</acronym> state (and avoid context switches). It - is generally a bad idea; use fixed point arithmetic first. - </para> - </listitem> - </varlistentry> - - <varlistentry> - <term>A rigid stack limit</term> - <listitem> - <para> - Depending on configuration options the kernel stack is about 3K to 6K for most 32-bit architectures: it's - about 14K on most 64-bit archs, and often shared with interrupts - so you can't use it all. Avoid deep recursion and huge local - arrays on the stack (allocate them dynamically instead). - </para> - </listitem> - </varlistentry> - - <varlistentry> - <term>The Linux kernel is portable</term> - <listitem> - <para> - Let's keep it that way. Your code should be 64-bit clean, - and endian-independent. You should also minimize CPU - specific stuff, e.g. inline assembly should be cleanly - encapsulated and minimized to ease porting. Generally it - should be restricted to the architecture-dependent part of - the kernel tree. - </para> - </listitem> - </varlistentry> - </variablelist> - </chapter> - - <chapter id="ioctls"> - <title>ioctls: Not writing a new system call</title> - - <para> - A system call generally looks like this - </para> - - <programlisting> -asmlinkage long sys_mycall(int arg) -{ - return 0; -} - </programlisting> - - <para> - First, in most cases you don't want to create a new system call. - You create a character device and implement an appropriate ioctl - for it. This is much more flexible than system calls, doesn't have - to be entered in every architecture's - <filename class="headerfile">include/asm/unistd.h</filename> and - <filename>arch/kernel/entry.S</filename> file, and is much more - likely to be accepted by Linus. - </para> - - <para> - If all your routine does is read or write some parameter, consider - implementing a <function>sysfs</function> interface instead. - </para> - - <para> - Inside the ioctl you're in user context to a process. When a - error occurs you return a negated errno (see - <filename class="headerfile">include/linux/errno.h</filename>), - otherwise you return <returnvalue>0</returnvalue>. - </para> - - <para> - After you slept you should check if a signal occurred: the - Unix/Linux way of handling signals is to temporarily exit the - system call with the <constant>-ERESTARTSYS</constant> error. The - system call entry code will switch back to user context, process - the signal handler and then your system call will be restarted - (unless the user disabled that). So you should be prepared to - process the restart, e.g. if you're in the middle of manipulating - some data structure. - </para> - - <programlisting> -if (signal_pending(current)) - return -ERESTARTSYS; - </programlisting> - - <para> - If you're doing longer computations: first think userspace. If you - <emphasis>really</emphasis> want to do it in kernel you should - regularly check if you need to give up the CPU (remember there is - cooperative multitasking per CPU). Idiom: - </para> - - <programlisting> -cond_resched(); /* Will sleep */ - </programlisting> - - <para> - A short note on interface design: the UNIX system call motto is - "Provide mechanism not policy". - </para> - </chapter> - - <chapter id="deadlock-recipes"> - <title>Recipes for Deadlock</title> - - <para> - You cannot call any routines which may sleep, unless: - </para> - <itemizedlist> - <listitem> - <para> - You are in user context. - </para> - </listitem> - - <listitem> - <para> - You do not own any spinlocks. - </para> - </listitem> - - <listitem> - <para> - You have interrupts enabled (actually, Andi Kleen says - that the scheduling code will enable them for you, but - that's probably not what you wanted). - </para> - </listitem> - </itemizedlist> - - <para> - Note that some functions may sleep implicitly: common ones are - the user space access functions (*_user) and memory allocation - functions without <symbol>GFP_ATOMIC</symbol>. - </para> - - <para> - You should always compile your kernel - <symbol>CONFIG_DEBUG_ATOMIC_SLEEP</symbol> on, and it will warn - you if you break these rules. If you <emphasis>do</emphasis> break - the rules, you will eventually lock up your box. - </para> - - <para> - Really. - </para> - </chapter> - - <chapter id="common-routines"> - <title>Common Routines</title> - - <sect1 id="routines-printk"> - <title> - <function>printk()</function> - <filename class="headerfile">include/linux/kernel.h</filename> - </title> - - <para> - <function>printk()</function> feeds kernel messages to the - console, dmesg, and the syslog daemon. It is useful for debugging - and reporting errors, and can be used inside interrupt context, - but use with caution: a machine which has its console flooded with - printk messages is unusable. It uses a format string mostly - compatible with ANSI C printf, and C string concatenation to give - it a first "priority" argument: - </para> - - <programlisting> -printk(KERN_INFO "i = %u\n", i); - </programlisting> - - <para> - See <filename class="headerfile">include/linux/kernel.h</filename>; - for other KERN_ values; these are interpreted by syslog as the - level. Special case: for printing an IP address use - </para> - - <programlisting> -__be32 ipaddress; -printk(KERN_INFO "my ip: %pI4\n", &ipaddress); - </programlisting> - - <para> - <function>printk()</function> internally uses a 1K buffer and does - not catch overruns. Make sure that will be enough. - </para> - - <note> - <para> - You will know when you are a real kernel hacker - when you start typoing printf as printk in your user programs :) - </para> - </note> - - <!--- From the Lions book reader department --> - - <note> - <para> - Another sidenote: the original Unix Version 6 sources had a - comment on top of its printf function: "Printf should not be - used for chit-chat". You should follow that advice. - </para> - </note> - </sect1> - - <sect1 id="routines-copy"> - <title> - <function>copy_[to/from]_user()</function> - / - <function>get_user()</function> - / - <function>put_user()</function> - <filename class="headerfile">include/linux/uaccess.h</filename> - </title> - - <para> - <emphasis>[SLEEPS]</emphasis> - </para> - - <para> - <function>put_user()</function> and <function>get_user()</function> - are used to get and put single values (such as an int, char, or - long) from and to userspace. A pointer into userspace should - never be simply dereferenced: data should be copied using these - routines. Both return <constant>-EFAULT</constant> or 0. - </para> - <para> - <function>copy_to_user()</function> and - <function>copy_from_user()</function> are more general: they copy - an arbitrary amount of data to and from userspace. - <caution> - <para> - Unlike <function>put_user()</function> and - <function>get_user()</function>, they return the amount of - uncopied data (ie. <returnvalue>0</returnvalue> still means - success). - </para> - </caution> - [Yes, this moronic interface makes me cringe. The flamewar comes up every year or so. --RR.] - </para> - <para> - The functions may sleep implicitly. This should never be called - outside user context (it makes no sense), with interrupts - disabled, or a spinlock held. - </para> - </sect1> - - <sect1 id="routines-kmalloc"> - <title><function>kmalloc()</function>/<function>kfree()</function> - <filename class="headerfile">include/linux/slab.h</filename></title> - - <para> - <emphasis>[MAY SLEEP: SEE BELOW]</emphasis> - </para> - - <para> - These routines are used to dynamically request pointer-aligned - chunks of memory, like malloc and free do in userspace, but - <function>kmalloc()</function> takes an extra flag word. - Important values: - </para> - - <variablelist> - <varlistentry> - <term> - <constant> - GFP_KERNEL - </constant> - </term> - <listitem> - <para> - May sleep and swap to free memory. Only allowed in user - context, but is the most reliable way to allocate memory. - </para> - </listitem> - </varlistentry> - - <varlistentry> - <term> - <constant> - GFP_ATOMIC - </constant> - </term> - <listitem> - <para> - Don't sleep. Less reliable than <constant>GFP_KERNEL</constant>, - but may be called from interrupt context. You should - <emphasis>really</emphasis> have a good out-of-memory - error-handling strategy. - </para> - </listitem> - </varlistentry> - - <varlistentry> - <term> - <constant> - GFP_DMA - </constant> - </term> - <listitem> - <para> - Allocate ISA DMA lower than 16MB. If you don't know what that - is you don't need it. Very unreliable. - </para> - </listitem> - </varlistentry> - </variablelist> - - <para> - If you see a <errorname>sleeping function called from invalid - context</errorname> warning message, then maybe you called a - sleeping allocation function from interrupt context without - <constant>GFP_ATOMIC</constant>. You should really fix that. - Run, don't walk. - </para> - - <para> - If you are allocating at least <constant>PAGE_SIZE</constant> - (<filename class="headerfile">include/asm/page.h</filename>) bytes, - consider using <function>__get_free_pages()</function> - - (<filename class="headerfile">include/linux/mm.h</filename>). It - takes an order argument (0 for page sized, 1 for double page, 2 - for four pages etc.) and the same memory priority flag word as - above. - </para> - - <para> - If you are allocating more than a page worth of bytes you can use - <function>vmalloc()</function>. It'll allocate virtual memory in - the kernel map. This block is not contiguous in physical memory, - but the <acronym>MMU</acronym> makes it look like it is for you - (so it'll only look contiguous to the CPUs, not to external device - drivers). If you really need large physically contiguous memory - for some weird device, you have a problem: it is poorly supported - in Linux because after some time memory fragmentation in a running - kernel makes it hard. The best way is to allocate the block early - in the boot process via the <function>alloc_bootmem()</function> - routine. - </para> - - <para> - Before inventing your own cache of often-used objects consider - using a slab cache in - <filename class="headerfile">include/linux/slab.h</filename> - </para> - </sect1> - - <sect1 id="routines-current"> - <title><function>current</function> - <filename class="headerfile">include/asm/current.h</filename></title> - - <para> - This global variable (really a macro) contains a pointer to - the current task structure, so is only valid in user context. - For example, when a process makes a system call, this will - point to the task structure of the calling process. It is - <emphasis>not NULL</emphasis> in interrupt context. - </para> - </sect1> - - <sect1 id="routines-udelay"> - <title><function>mdelay()</function>/<function>udelay()</function> - <filename class="headerfile">include/asm/delay.h</filename> - <filename class="headerfile">include/linux/delay.h</filename> - </title> - - <para> - The <function>udelay()</function> and <function>ndelay()</function> functions can be used for small pauses. - Do not use large values with them as you risk - overflow - the helper function <function>mdelay()</function> is useful - here, or consider <function>msleep()</function>. - </para> - </sect1> - - <sect1 id="routines-endian"> - <title><function>cpu_to_be32()</function>/<function>be32_to_cpu()</function>/<function>cpu_to_le32()</function>/<function>le32_to_cpu()</function> - <filename class="headerfile">include/asm/byteorder.h</filename> - </title> - - <para> - The <function>cpu_to_be32()</function> family (where the "32" can - be replaced by 64 or 16, and the "be" can be replaced by "le") are - the general way to do endian conversions in the kernel: they - return the converted value. All variations supply the reverse as - well: <function>be32_to_cpu()</function>, etc. - </para> - - <para> - There are two major variations of these functions: the pointer - variation, such as <function>cpu_to_be32p()</function>, which take - a pointer to the given type, and return the converted value. The - other variation is the "in-situ" family, such as - <function>cpu_to_be32s()</function>, which convert value referred - to by the pointer, and return void. - </para> - </sect1> - - <sect1 id="routines-local-irqs"> - <title><function>local_irq_save()</function>/<function>local_irq_restore()</function> - <filename class="headerfile">include/linux/irqflags.h</filename> - </title> - - <para> - These routines disable hard interrupts on the local CPU, and - restore them. They are reentrant; saving the previous state in - their one <varname>unsigned long flags</varname> argument. If you - know that interrupts are enabled, you can simply use - <function>local_irq_disable()</function> and - <function>local_irq_enable()</function>. - </para> - </sect1> - - <sect1 id="routines-softirqs"> - <title><function>local_bh_disable()</function>/<function>local_bh_enable()</function> - <filename class="headerfile">include/linux/interrupt.h</filename></title> - - <para> - These routines disable soft interrupts on the local CPU, and - restore them. They are reentrant; if soft interrupts were - disabled before, they will still be disabled after this pair - of functions has been called. They prevent softirqs and tasklets - from running on the current CPU. - </para> - </sect1> - - <sect1 id="routines-processorids"> - <title><function>smp_processor_id</function>() - <filename class="headerfile">include/asm/smp.h</filename></title> - - <para> - <function>get_cpu()</function> disables preemption (so you won't - suddenly get moved to another CPU) and returns the current - processor number, between 0 and <symbol>NR_CPUS</symbol>. Note - that the CPU numbers are not necessarily continuous. You return - it again with <function>put_cpu()</function> when you are done. - </para> - <para> - If you know you cannot be preempted by another task (ie. you are - in interrupt context, or have preemption disabled) you can use - smp_processor_id(). - </para> - </sect1> - - <sect1 id="routines-init"> - <title><type>__init</type>/<type>__exit</type>/<type>__initdata</type> - <filename class="headerfile">include/linux/init.h</filename></title> - - <para> - After boot, the kernel frees up a special section; functions - marked with <type>__init</type> and data structures marked with - <type>__initdata</type> are dropped after boot is complete: similarly - modules discard this memory after initialization. <type>__exit</type> - is used to declare a function which is only required on exit: the - function will be dropped if this file is not compiled as a module. - See the header file for use. Note that it makes no sense for a function - marked with <type>__init</type> to be exported to modules with - <function>EXPORT_SYMBOL()</function> - this will break. - </para> - - </sect1> - - <sect1 id="routines-init-again"> - <title><function>__initcall()</function>/<function>module_init()</function> - <filename class="headerfile">include/linux/init.h</filename></title> - <para> - Many parts of the kernel are well served as a module - (dynamically-loadable parts of the kernel). Using the - <function>module_init()</function> and - <function>module_exit()</function> macros it is easy to write code - without #ifdefs which can operate both as a module or built into - the kernel. - </para> - - <para> - The <function>module_init()</function> macro defines which - function is to be called at module insertion time (if the file is - compiled as a module), or at boot time: if the file is not - compiled as a module the <function>module_init()</function> macro - becomes equivalent to <function>__initcall()</function>, which - through linker magic ensures that the function is called on boot. - </para> - - <para> - The function can return a negative error number to cause - module loading to fail (unfortunately, this has no effect if - the module is compiled into the kernel). This function is - called in user context with interrupts enabled, so it can sleep. - </para> - </sect1> - - <sect1 id="routines-moduleexit"> - <title> <function>module_exit()</function> - <filename class="headerfile">include/linux/init.h</filename> </title> - - <para> - This macro defines the function to be called at module removal - time (or never, in the case of the file compiled into the - kernel). It will only be called if the module usage count has - reached zero. This function can also sleep, but cannot fail: - everything must be cleaned up by the time it returns. - </para> - - <para> - Note that this macro is optional: if it is not present, your - module will not be removable (except for 'rmmod -f'). - </para> - </sect1> - - <sect1 id="routines-module-use-counters"> - <title> <function>try_module_get()</function>/<function>module_put()</function> - <filename class="headerfile">include/linux/module.h</filename></title> - - <para> - These manipulate the module usage count, to protect against - removal (a module also can't be removed if another module uses one - of its exported symbols: see below). Before calling into module - code, you should call <function>try_module_get()</function> on - that module: if it fails, then the module is being removed and you - should act as if it wasn't there. Otherwise, you can safely enter - the module, and call <function>module_put()</function> when you're - finished. - </para> - - <para> - Most registerable structures have an - <structfield>owner</structfield> field, such as in the - <structname>file_operations</structname> structure. Set this field - to the macro <symbol>THIS_MODULE</symbol>. - </para> - </sect1> - - <!-- add info on new-style module refcounting here --> - </chapter> - - <chapter id="queues"> - <title>Wait Queues - <filename class="headerfile">include/linux/wait.h</filename> - </title> - <para> - <emphasis>[SLEEPS]</emphasis> - </para> - - <para> - A wait queue is used to wait for someone to wake you up when a - certain condition is true. They must be used carefully to ensure - there is no race condition. You declare a - <type>wait_queue_head_t</type>, and then processes which want to - wait for that condition declare a <type>wait_queue_t</type> - referring to themselves, and place that in the queue. - </para> - - <sect1 id="queue-declaring"> - <title>Declaring</title> - - <para> - You declare a <type>wait_queue_head_t</type> using the - <function>DECLARE_WAIT_QUEUE_HEAD()</function> macro, or using the - <function>init_waitqueue_head()</function> routine in your - initialization code. - </para> - </sect1> - - <sect1 id="queue-waitqueue"> - <title>Queuing</title> - - <para> - Placing yourself in the waitqueue is fairly complex, because you - must put yourself in the queue before checking the condition. - There is a macro to do this: - <function>wait_event_interruptible()</function> - - <filename class="headerfile">include/linux/wait.h</filename> The - first argument is the wait queue head, and the second is an - expression which is evaluated; the macro returns - <returnvalue>0</returnvalue> when this expression is true, or - <returnvalue>-ERESTARTSYS</returnvalue> if a signal is received. - The <function>wait_event()</function> version ignores signals. - </para> - - </sect1> - - <sect1 id="queue-waking"> - <title>Waking Up Queued Tasks</title> - - <para> - Call <function>wake_up()</function> - - <filename class="headerfile">include/linux/wait.h</filename>;, - which will wake up every process in the queue. The exception is - if one has <constant>TASK_EXCLUSIVE</constant> set, in which case - the remainder of the queue will not be woken. There are other variants - of this basic function available in the same header. - </para> - </sect1> - </chapter> - - <chapter id="atomic-ops"> - <title>Atomic Operations</title> - - <para> - Certain operations are guaranteed atomic on all platforms. The - first class of operations work on <type>atomic_t</type> - - <filename class="headerfile">include/asm/atomic.h</filename>; this - contains a signed integer (at least 32 bits long), and you must use - these functions to manipulate or read atomic_t variables. - <function>atomic_read()</function> and - <function>atomic_set()</function> get and set the counter, - <function>atomic_add()</function>, - <function>atomic_sub()</function>, - <function>atomic_inc()</function>, - <function>atomic_dec()</function>, and - <function>atomic_dec_and_test()</function> (returns - <returnvalue>true</returnvalue> if it was decremented to zero). - </para> - - <para> - Yes. It returns <returnvalue>true</returnvalue> (i.e. != 0) if the - atomic variable is zero. - </para> - - <para> - Note that these functions are slower than normal arithmetic, and - so should not be used unnecessarily. - </para> - - <para> - The second class of atomic operations is atomic bit operations on an - <type>unsigned long</type>, defined in - - <filename class="headerfile">include/linux/bitops.h</filename>. These - operations generally take a pointer to the bit pattern, and a bit - number: 0 is the least significant bit. - <function>set_bit()</function>, <function>clear_bit()</function> - and <function>change_bit()</function> set, clear, and flip the - given bit. <function>test_and_set_bit()</function>, - <function>test_and_clear_bit()</function> and - <function>test_and_change_bit()</function> do the same thing, - except return true if the bit was previously set; these are - particularly useful for atomically setting flags. - </para> - - <para> - It is possible to call these operations with bit indices greater - than BITS_PER_LONG. The resulting behavior is strange on big-endian - platforms though so it is a good idea not to do this. - </para> - </chapter> - - <chapter id="symbols"> - <title>Symbols</title> - - <para> - Within the kernel proper, the normal linking rules apply - (ie. unless a symbol is declared to be file scope with the - <type>static</type> keyword, it can be used anywhere in the - kernel). However, for modules, a special exported symbol table is - kept which limits the entry points to the kernel proper. Modules - can also export symbols. - </para> - - <sect1 id="sym-exportsymbols"> - <title><function>EXPORT_SYMBOL()</function> - <filename class="headerfile">include/linux/export.h</filename></title> - - <para> - This is the classic method of exporting a symbol: dynamically - loaded modules will be able to use the symbol as normal. - </para> - </sect1> - - <sect1 id="sym-exportsymbols-gpl"> - <title><function>EXPORT_SYMBOL_GPL()</function> - <filename class="headerfile">include/linux/export.h</filename></title> - - <para> - Similar to <function>EXPORT_SYMBOL()</function> except that the - symbols exported by <function>EXPORT_SYMBOL_GPL()</function> can - only be seen by modules with a - <function>MODULE_LICENSE()</function> that specifies a GPL - compatible license. It implies that the function is considered - an internal implementation issue, and not really an interface. - Some maintainers and developers may however - require EXPORT_SYMBOL_GPL() when adding any new APIs or functionality. - </para> - </sect1> - </chapter> - - <chapter id="conventions"> - <title>Routines and Conventions</title> - - <sect1 id="conventions-doublelinkedlist"> - <title>Double-linked lists - <filename class="headerfile">include/linux/list.h</filename></title> - - <para> - There used to be three sets of linked-list routines in the kernel - headers, but this one is the winner. If you don't have some - particular pressing need for a single list, it's a good choice. - </para> - - <para> - In particular, <function>list_for_each_entry</function> is useful. - </para> - </sect1> - - <sect1 id="convention-returns"> - <title>Return Conventions</title> - - <para> - For code called in user context, it's very common to defy C - convention, and return <returnvalue>0</returnvalue> for success, - and a negative error number - (eg. <returnvalue>-EFAULT</returnvalue>) for failure. This can be - unintuitive at first, but it's fairly widespread in the kernel. - </para> - - <para> - Using <function>ERR_PTR()</function> - - <filename class="headerfile">include/linux/err.h</filename>; to - encode a negative error number into a pointer, and - <function>IS_ERR()</function> and <function>PTR_ERR()</function> - to get it back out again: avoids a separate pointer parameter for - the error number. Icky, but in a good way. - </para> - </sect1> - - <sect1 id="conventions-borkedcompile"> - <title>Breaking Compilation</title> - - <para> - Linus and the other developers sometimes change function or - structure names in development kernels; this is not done just to - keep everyone on their toes: it reflects a fundamental change - (eg. can no longer be called with interrupts on, or does extra - checks, or doesn't do checks which were caught before). Usually - this is accompanied by a fairly complete note to the linux-kernel - mailing list; search the archive. Simply doing a global replace - on the file usually makes things <emphasis>worse</emphasis>. - </para> - </sect1> - - <sect1 id="conventions-initialising"> - <title>Initializing structure members</title> - - <para> - The preferred method of initializing structures is to use - designated initialisers, as defined by ISO C99, eg: - </para> - <programlisting> -static struct block_device_operations opt_fops = { - .open = opt_open, - .release = opt_release, - .ioctl = opt_ioctl, - .check_media_change = opt_media_change, -}; - </programlisting> - <para> - This makes it easy to grep for, and makes it clear which - structure fields are set. You should do this because it looks - cool. - </para> - </sect1> - - <sect1 id="conventions-gnu-extns"> - <title>GNU Extensions</title> - - <para> - GNU Extensions are explicitly allowed in the Linux kernel. - Note that some of the more complex ones are not very well - supported, due to lack of general use, but the following are - considered standard (see the GCC info page section "C - Extensions" for more details - Yes, really the info page, the - man page is only a short summary of the stuff in info). - </para> - <itemizedlist> - <listitem> - <para> - Inline functions - </para> - </listitem> - <listitem> - <para> - Statement expressions (ie. the ({ and }) constructs). - </para> - </listitem> - <listitem> - <para> - Declaring attributes of a function / variable / type - (__attribute__) - </para> - </listitem> - <listitem> - <para> - typeof - </para> - </listitem> - <listitem> - <para> - Zero length arrays - </para> - </listitem> - <listitem> - <para> - Macro varargs - </para> - </listitem> - <listitem> - <para> - Arithmetic on void pointers - </para> - </listitem> - <listitem> - <para> - Non-Constant initializers - </para> - </listitem> - <listitem> - <para> - Assembler Instructions (not outside arch/ and include/asm/) - </para> - </listitem> - <listitem> - <para> - Function names as strings (__func__). - </para> - </listitem> - <listitem> - <para> - __builtin_constant_p() - </para> - </listitem> - </itemizedlist> - - <para> - Be wary when using long long in the kernel, the code gcc generates for - it is horrible and worse: division and multiplication does not work - on i386 because the GCC runtime functions for it are missing from - the kernel environment. - </para> - - <!-- FIXME: add a note about ANSI aliasing cleanness --> - </sect1> - - <sect1 id="conventions-cplusplus"> - <title>C++</title> - - <para> - Using C++ in the kernel is usually a bad idea, because the - kernel does not provide the necessary runtime environment - and the include files are not tested for it. It is still - possible, but not recommended. If you really want to do - this, forget about exceptions at least. - </para> - </sect1> - - <sect1 id="conventions-ifdef"> - <title>#if</title> - - <para> - It is generally considered cleaner to use macros in header files - (or at the top of .c files) to abstract away functions rather than - using `#if' pre-processor statements throughout the source code. - </para> - </sect1> - </chapter> - - <chapter id="submitting"> - <title>Putting Your Stuff in the Kernel</title> - - <para> - In order to get your stuff into shape for official inclusion, or - even to make a neat patch, there's administrative work to be - done: - </para> - <itemizedlist> - <listitem> - <para> - Figure out whose pond you've been pissing in. Look at the top of - the source files, inside the <filename>MAINTAINERS</filename> - file, and last of all in the <filename>CREDITS</filename> file. - You should coordinate with this person to make sure you're not - duplicating effort, or trying something that's already been - rejected. - </para> - - <para> - Make sure you put your name and EMail address at the top of - any files you create or mangle significantly. This is the - first place people will look when they find a bug, or when - <emphasis>they</emphasis> want to make a change. - </para> - </listitem> - - <listitem> - <para> - Usually you want a configuration option for your kernel hack. - Edit <filename>Kconfig</filename> in the appropriate directory. - The Config language is simple to use by cut and paste, and there's - complete documentation in - <filename>Documentation/kbuild/kconfig-language.txt</filename>. - </para> - - <para> - In your description of the option, make sure you address both the - expert user and the user who knows nothing about your feature. Mention - incompatibilities and issues here. <emphasis> Definitely - </emphasis> end your description with <quote> if in doubt, say N - </quote> (or, occasionally, `Y'); this is for people who have no - idea what you are talking about. - </para> - </listitem> - - <listitem> - <para> - Edit the <filename>Makefile</filename>: the CONFIG variables are - exported here so you can usually just add a "obj-$(CONFIG_xxx) += - xxx.o" line. The syntax is documented in - <filename>Documentation/kbuild/makefiles.txt</filename>. - </para> - </listitem> - - <listitem> - <para> - Put yourself in <filename>CREDITS</filename> if you've done - something noteworthy, usually beyond a single file (your name - should be at the top of the source files anyway). - <filename>MAINTAINERS</filename> means you want to be consulted - when changes are made to a subsystem, and hear about bugs; it - implies a more-than-passing commitment to some part of the code. - </para> - </listitem> - - <listitem> - <para> - Finally, don't forget to read <filename>Documentation/process/submitting-patches.rst</filename> - and possibly <filename>Documentation/process/submitting-drivers.rst</filename>. - </para> - </listitem> - </itemizedlist> - </chapter> - - <chapter id="cantrips"> - <title>Kernel Cantrips</title> - - <para> - Some favorites from browsing the source. Feel free to add to this - list. - </para> - - <para> - <filename>arch/x86/include/asm/delay.h:</filename> - </para> - <programlisting> -#define ndelay(n) (__builtin_constant_p(n) ? \ - ((n) > 20000 ? __bad_ndelay() : __const_udelay((n) * 5ul)) : \ - __ndelay(n)) - </programlisting> - - <para> - <filename>include/linux/fs.h</filename>: - </para> - <programlisting> -/* - * Kernel pointers have redundant information, so we can use a - * scheme where we can return either an error code or a dentry - * pointer with the same return value. - * - * This should be a per-architecture thing, to allow different - * error and pointer decisions. - */ - #define ERR_PTR(err) ((void *)((long)(err))) - #define PTR_ERR(ptr) ((long)(ptr)) - #define IS_ERR(ptr) ((unsigned long)(ptr) > (unsigned long)(-1000)) -</programlisting> - - <para> - <filename>arch/x86/include/asm/uaccess_32.h:</filename> - </para> - - <programlisting> -#define copy_to_user(to,from,n) \ - (__builtin_constant_p(n) ? \ - __constant_copy_to_user((to),(from),(n)) : \ - __generic_copy_to_user((to),(from),(n))) - </programlisting> - - <para> - <filename>arch/sparc/kernel/head.S:</filename> - </para> - - <programlisting> -/* - * Sun people can't spell worth damn. "compatability" indeed. - * At least we *know* we can't spell, and use a spell-checker. - */ - -/* Uh, actually Linus it is I who cannot spell. Too much murky - * Sparc assembly will do this to ya. - */ -C_LABEL(cputypvar): - .asciz "compatibility" - -/* Tested on SS-5, SS-10. Probably someone at Sun applied a spell-checker. */ - .align 4 -C_LABEL(cputypvar_sun4m): - .asciz "compatible" - </programlisting> - - <para> - <filename>arch/sparc/lib/checksum.S:</filename> - </para> - - <programlisting> - /* Sun, you just can't beat me, you just can't. Stop trying, - * give up. I'm serious, I am going to kick the living shit - * out of you, game over, lights out. - */ - </programlisting> - </chapter> - - <chapter id="credits"> - <title>Thanks</title> - - <para> - Thanks to Andi Kleen for the idea, answering my questions, fixing - my mistakes, filling content, etc. Philipp Rumpf for more spelling - and clarity fixes, and some excellent non-obvious points. Werner - Almesberger for giving me a great summary of - <function>disable_irq()</function>, and Jes Sorensen and Andrea - Arcangeli added caveats. Michael Elizabeth Chastain for checking - and adding to the Configure section. <!-- Rusty insisted on this - bit; I didn't do it! --> Telsa Gwynne for teaching me DocBook. - </para> - </chapter> -</book> - diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl deleted file mode 100644 index 7c9cc4846cb6..000000000000 --- a/Documentation/DocBook/kernel-locking.tmpl +++ /dev/null @@ -1,2151 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="LKLockingGuide"> - <bookinfo> - <title>Unreliable Guide To Locking</title> - - <authorgroup> - <author> - <firstname>Rusty</firstname> - <surname>Russell</surname> - <affiliation> - <address> - <email>rusty@rustcorp.com.au</email> - </address> - </affiliation> - </author> - </authorgroup> - - <copyright> - <year>2003</year> - <holder>Rusty Russell</holder> - </copyright> - - <legalnotice> - <para> - This documentation is free software; you can redistribute - it and/or modify it under the terms of the GNU General Public - License as published by the Free Software Foundation; either - version 2 of the License, or (at your option) any later - version. - </para> - - <para> - This program is distributed in the hope that it will be - useful, but WITHOUT ANY WARRANTY; without even the implied - warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. - See the GNU General Public License for more details. - </para> - - <para> - You should have received a copy of the GNU General Public - License along with this program; if not, write to the Free - Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, - MA 02111-1307 USA - </para> - - <para> - For more details see the file COPYING in the source - distribution of Linux. - </para> - </legalnotice> - </bookinfo> - - <toc></toc> - <chapter id="intro"> - <title>Introduction</title> - <para> - Welcome, to Rusty's Remarkably Unreliable Guide to Kernel - Locking issues. This document describes the locking systems in - the Linux Kernel in 2.6. - </para> - <para> - With the wide availability of HyperThreading, and <firstterm - linkend="gloss-preemption">preemption </firstterm> in the Linux - Kernel, everyone hacking on the kernel needs to know the - fundamentals of concurrency and locking for - <firstterm linkend="gloss-smp"><acronym>SMP</acronym></firstterm>. - </para> - </chapter> - - <chapter id="races"> - <title>The Problem With Concurrency</title> - <para> - (Skip this if you know what a Race Condition is). - </para> - <para> - In a normal program, you can increment a counter like so: - </para> - <programlisting> - very_important_count++; - </programlisting> - - <para> - This is what they would expect to happen: - </para> - - <table> - <title>Expected Results</title> - - <tgroup cols="2" align="left"> - - <thead> - <row> - <entry>Instance 1</entry> - <entry>Instance 2</entry> - </row> - </thead> - - <tbody> - <row> - <entry>read very_important_count (5)</entry> - <entry></entry> - </row> - <row> - <entry>add 1 (6)</entry> - <entry></entry> - </row> - <row> - <entry>write very_important_count (6)</entry> - <entry></entry> - </row> - <row> - <entry></entry> - <entry>read very_important_count (6)</entry> - </row> - <row> - <entry></entry> - <entry>add 1 (7)</entry> - </row> - <row> - <entry></entry> - <entry>write very_important_count (7)</entry> - </row> - </tbody> - - </tgroup> - </table> - - <para> - This is what might happen: - </para> - - <table> - <title>Possible Results</title> - - <tgroup cols="2" align="left"> - <thead> - <row> - <entry>Instance 1</entry> - <entry>Instance 2</entry> - </row> - </thead> - - <tbody> - <row> - <entry>read very_important_count (5)</entry> - <entry></entry> - </row> - <row> - <entry></entry> - <entry>read very_important_count (5)</entry> - </row> - <row> - <entry>add 1 (6)</entry> - <entry></entry> - </row> - <row> - <entry></entry> - <entry>add 1 (6)</entry> - </row> - <row> - <entry>write very_important_count (6)</entry> - <entry></entry> - </row> - <row> - <entry></entry> - <entry>write very_important_count (6)</entry> - </row> - </tbody> - </tgroup> - </table> - - <sect1 id="race-condition"> - <title>Race Conditions and Critical Regions</title> - <para> - This overlap, where the result depends on the - relative timing of multiple tasks, is called a <firstterm>race condition</firstterm>. - The piece of code containing the concurrency issue is called a - <firstterm>critical region</firstterm>. And especially since Linux starting running - on SMP machines, they became one of the major issues in kernel - design and implementation. - </para> - <para> - Preemption can have the same effect, even if there is only one - CPU: by preempting one task during the critical region, we have - exactly the same race condition. In this case the thread which - preempts might run the critical region itself. - </para> - <para> - The solution is to recognize when these simultaneous accesses - occur, and use locks to make sure that only one instance can - enter the critical region at any time. There are many - friendly primitives in the Linux kernel to help you do this. - And then there are the unfriendly primitives, but I'll pretend - they don't exist. - </para> - </sect1> - </chapter> - - <chapter id="locks"> - <title>Locking in the Linux Kernel</title> - - <para> - If I could give you one piece of advice: never sleep with anyone - crazier than yourself. But if I had to give you advice on - locking: <emphasis>keep it simple</emphasis>. - </para> - - <para> - Be reluctant to introduce new locks. - </para> - - <para> - Strangely enough, this last one is the exact reverse of my advice when - you <emphasis>have</emphasis> slept with someone crazier than yourself. - And you should think about getting a big dog. - </para> - - <sect1 id="lock-intro"> - <title>Two Main Types of Kernel Locks: Spinlocks and Mutexes</title> - - <para> - There are two main types of kernel locks. The fundamental type - is the spinlock - (<filename class="headerfile">include/asm/spinlock.h</filename>), - which is a very simple single-holder lock: if you can't get the - spinlock, you keep trying (spinning) until you can. Spinlocks are - very small and fast, and can be used anywhere. - </para> - <para> - The second type is a mutex - (<filename class="headerfile">include/linux/mutex.h</filename>): it - is like a spinlock, but you may block holding a mutex. - If you can't lock a mutex, your task will suspend itself, and be woken - up when the mutex is released. This means the CPU can do something - else while you are waiting. There are many cases when you simply - can't sleep (see <xref linkend="sleeping-things"/>), and so have to - use a spinlock instead. - </para> - <para> - Neither type of lock is recursive: see - <xref linkend="deadlock"/>. - </para> - </sect1> - - <sect1 id="uniprocessor"> - <title>Locks and Uniprocessor Kernels</title> - - <para> - For kernels compiled without <symbol>CONFIG_SMP</symbol>, and - without <symbol>CONFIG_PREEMPT</symbol> spinlocks do not exist at - all. This is an excellent design decision: when no-one else can - run at the same time, there is no reason to have a lock. - </para> - - <para> - If the kernel is compiled without <symbol>CONFIG_SMP</symbol>, - but <symbol>CONFIG_PREEMPT</symbol> is set, then spinlocks - simply disable preemption, which is sufficient to prevent any - races. For most purposes, we can think of preemption as - equivalent to SMP, and not worry about it separately. - </para> - - <para> - You should always test your locking code with <symbol>CONFIG_SMP</symbol> - and <symbol>CONFIG_PREEMPT</symbol> enabled, even if you don't have an SMP test box, because it - will still catch some kinds of locking bugs. - </para> - - <para> - Mutexes still exist, because they are required for - synchronization between <firstterm linkend="gloss-usercontext">user - contexts</firstterm>, as we will see below. - </para> - </sect1> - - <sect1 id="usercontextlocking"> - <title>Locking Only In User Context</title> - - <para> - If you have a data structure which is only ever accessed from - user context, then you can use a simple mutex - (<filename>include/linux/mutex.h</filename>) to protect it. This - is the most trivial case: you initialize the mutex. Then you can - call <function>mutex_lock_interruptible()</function> to grab the mutex, - and <function>mutex_unlock()</function> to release it. There is also a - <function>mutex_lock()</function>, which should be avoided, because it - will not return if a signal is received. - </para> - - <para> - Example: <filename>net/netfilter/nf_sockopt.c</filename> allows - registration of new <function>setsockopt()</function> and - <function>getsockopt()</function> calls, with - <function>nf_register_sockopt()</function>. Registration and - de-registration are only done on module load and unload (and boot - time, where there is no concurrency), and the list of registrations - is only consulted for an unknown <function>setsockopt()</function> - or <function>getsockopt()</function> system call. The - <varname>nf_sockopt_mutex</varname> is perfect to protect this, - especially since the setsockopt and getsockopt calls may well - sleep. - </para> - </sect1> - - <sect1 id="lock-user-bh"> - <title>Locking Between User Context and Softirqs</title> - - <para> - If a <firstterm linkend="gloss-softirq">softirq</firstterm> shares - data with user context, you have two problems. Firstly, the current - user context can be interrupted by a softirq, and secondly, the - critical region could be entered from another CPU. This is where - <function>spin_lock_bh()</function> - (<filename class="headerfile">include/linux/spinlock.h</filename>) is - used. It disables softirqs on that CPU, then grabs the lock. - <function>spin_unlock_bh()</function> does the reverse. (The - '_bh' suffix is a historical reference to "Bottom Halves", the - old name for software interrupts. It should really be - called spin_lock_softirq()' in a perfect world). - </para> - - <para> - Note that you can also use <function>spin_lock_irq()</function> - or <function>spin_lock_irqsave()</function> here, which stop - hardware interrupts as well: see <xref linkend="hardirq-context"/>. - </para> - - <para> - This works perfectly for <firstterm linkend="gloss-up"><acronym>UP - </acronym></firstterm> as well: the spin lock vanishes, and this macro - simply becomes <function>local_bh_disable()</function> - (<filename class="headerfile">include/linux/interrupt.h</filename>), which - protects you from the softirq being run. - </para> - </sect1> - - <sect1 id="lock-user-tasklet"> - <title>Locking Between User Context and Tasklets</title> - - <para> - This is exactly the same as above, because <firstterm - linkend="gloss-tasklet">tasklets</firstterm> are actually run - from a softirq. - </para> - </sect1> - - <sect1 id="lock-user-timers"> - <title>Locking Between User Context and Timers</title> - - <para> - This, too, is exactly the same as above, because <firstterm - linkend="gloss-timers">timers</firstterm> are actually run from - a softirq. From a locking point of view, tasklets and timers - are identical. - </para> - </sect1> - - <sect1 id="lock-tasklets"> - <title>Locking Between Tasklets/Timers</title> - - <para> - Sometimes a tasklet or timer might want to share data with - another tasklet or timer. - </para> - - <sect2 id="lock-tasklets-same"> - <title>The Same Tasklet/Timer</title> - <para> - Since a tasklet is never run on two CPUs at once, you don't - need to worry about your tasklet being reentrant (running - twice at once), even on SMP. - </para> - </sect2> - - <sect2 id="lock-tasklets-different"> - <title>Different Tasklets/Timers</title> - <para> - If another tasklet/timer wants - to share data with your tasklet or timer , you will both need to use - <function>spin_lock()</function> and - <function>spin_unlock()</function> calls. - <function>spin_lock_bh()</function> is - unnecessary here, as you are already in a tasklet, and - none will be run on the same CPU. - </para> - </sect2> - </sect1> - - <sect1 id="lock-softirqs"> - <title>Locking Between Softirqs</title> - - <para> - Often a softirq might - want to share data with itself or a tasklet/timer. - </para> - - <sect2 id="lock-softirqs-same"> - <title>The Same Softirq</title> - - <para> - The same softirq can run on the other CPUs: you can use a - per-CPU array (see <xref linkend="per-cpu"/>) for better - performance. If you're going so far as to use a softirq, - you probably care about scalable performance enough - to justify the extra complexity. - </para> - - <para> - You'll need to use <function>spin_lock()</function> and - <function>spin_unlock()</function> for shared data. - </para> - </sect2> - - <sect2 id="lock-softirqs-different"> - <title>Different Softirqs</title> - - <para> - You'll need to use <function>spin_lock()</function> and - <function>spin_unlock()</function> for shared data, whether it - be a timer, tasklet, different softirq or the same or another - softirq: any of them could be running on a different CPU. - </para> - </sect2> - </sect1> - </chapter> - - <chapter id="hardirq-context"> - <title>Hard IRQ Context</title> - - <para> - Hardware interrupts usually communicate with a - tasklet or softirq. Frequently this involves putting work in a - queue, which the softirq will take out. - </para> - - <sect1 id="hardirq-softirq"> - <title>Locking Between Hard IRQ and Softirqs/Tasklets</title> - - <para> - If a hardware irq handler shares data with a softirq, you have - two concerns. Firstly, the softirq processing can be - interrupted by a hardware interrupt, and secondly, the - critical region could be entered by a hardware interrupt on - another CPU. This is where <function>spin_lock_irq()</function> is - used. It is defined to disable interrupts on that cpu, then grab - the lock. <function>spin_unlock_irq()</function> does the reverse. - </para> - - <para> - The irq handler does not to use - <function>spin_lock_irq()</function>, because the softirq cannot - run while the irq handler is running: it can use - <function>spin_lock()</function>, which is slightly faster. The - only exception would be if a different hardware irq handler uses - the same lock: <function>spin_lock_irq()</function> will stop - that from interrupting us. - </para> - - <para> - This works perfectly for UP as well: the spin lock vanishes, - and this macro simply becomes <function>local_irq_disable()</function> - (<filename class="headerfile">include/asm/smp.h</filename>), which - protects you from the softirq/tasklet/BH being run. - </para> - - <para> - <function>spin_lock_irqsave()</function> - (<filename>include/linux/spinlock.h</filename>) is a variant - which saves whether interrupts were on or off in a flags word, - which is passed to <function>spin_unlock_irqrestore()</function>. This - means that the same code can be used inside an hard irq handler (where - interrupts are already off) and in softirqs (where the irq - disabling is required). - </para> - - <para> - Note that softirqs (and hence tasklets and timers) are run on - return from hardware interrupts, so - <function>spin_lock_irq()</function> also stops these. In that - sense, <function>spin_lock_irqsave()</function> is the most - general and powerful locking function. - </para> - - </sect1> - <sect1 id="hardirq-hardirq"> - <title>Locking Between Two Hard IRQ Handlers</title> - <para> - It is rare to have to share data between two IRQ handlers, but - if you do, <function>spin_lock_irqsave()</function> should be - used: it is architecture-specific whether all interrupts are - disabled inside irq handlers themselves. - </para> - </sect1> - - </chapter> - - <chapter id="cheatsheet"> - <title>Cheat Sheet For Locking</title> - <para> - Pete Zaitcev gives the following summary: - </para> - <itemizedlist> - <listitem> - <para> - If you are in a process context (any syscall) and want to - lock other process out, use a mutex. You can take a mutex - and sleep (<function>copy_from_user*(</function> or - <function>kmalloc(x,GFP_KERNEL)</function>). - </para> - </listitem> - <listitem> - <para> - Otherwise (== data can be touched in an interrupt), use - <function>spin_lock_irqsave()</function> and - <function>spin_unlock_irqrestore()</function>. - </para> - </listitem> - <listitem> - <para> - Avoid holding spinlock for more than 5 lines of code and - across any function call (except accessors like - <function>readb</function>). - </para> - </listitem> - </itemizedlist> - - <sect1 id="minimum-lock-reqirements"> - <title>Table of Minimum Requirements</title> - - <para> The following table lists the <emphasis>minimum</emphasis> - locking requirements between various contexts. In some cases, - the same context can only be running on one CPU at a time, so - no locking is required for that context (eg. a particular - thread can only run on one CPU at a time, but if it needs - shares data with another thread, locking is required). - </para> - <para> - Remember the advice above: you can always use - <function>spin_lock_irqsave()</function>, which is a superset - of all other spinlock primitives. - </para> - - <table> -<title>Table of Locking Requirements</title> -<tgroup cols="11"> -<tbody> - -<row> -<entry></entry> -<entry>IRQ Handler A</entry> -<entry>IRQ Handler B</entry> -<entry>Softirq A</entry> -<entry>Softirq B</entry> -<entry>Tasklet A</entry> -<entry>Tasklet B</entry> -<entry>Timer A</entry> -<entry>Timer B</entry> -<entry>User Context A</entry> -<entry>User Context B</entry> -</row> - -<row> -<entry>IRQ Handler A</entry> -<entry>None</entry> -</row> - -<row> -<entry>IRQ Handler B</entry> -<entry>SLIS</entry> -<entry>None</entry> -</row> - -<row> -<entry>Softirq A</entry> -<entry>SLI</entry> -<entry>SLI</entry> -<entry>SL</entry> -</row> - -<row> -<entry>Softirq B</entry> -<entry>SLI</entry> -<entry>SLI</entry> -<entry>SL</entry> -<entry>SL</entry> -</row> - -<row> -<entry>Tasklet A</entry> -<entry>SLI</entry> -<entry>SLI</entry> -<entry>SL</entry> -<entry>SL</entry> -<entry>None</entry> -</row> - -<row> -<entry>Tasklet B</entry> -<entry>SLI</entry> -<entry>SLI</entry> -<entry>SL</entry> -<entry>SL</entry> -<entry>SL</entry> -<entry>None</entry> -</row> - -<row> -<entry>Timer A</entry> -<entry>SLI</entry> -<entry>SLI</entry> -<entry>SL</entry> -<entry>SL</entry> -<entry>SL</entry> -<entry>SL</entry> -<entry>None</entry> -</row> - -<row> -<entry>Timer B</entry> -<entry>SLI</entry> -<entry>SLI</entry> -<entry>SL</entry> -<entry>SL</entry> -<entry>SL</entry> -<entry>SL</entry> -<entry>SL</entry> -<entry>None</entry> -</row> - -<row> -<entry>User Context A</entry> -<entry>SLI</entry> -<entry>SLI</entry> -<entry>SLBH</entry> -<entry>SLBH</entry> -<entry>SLBH</entry> -<entry>SLBH</entry> -<entry>SLBH</entry> -<entry>SLBH</entry> -<entry>None</entry> -</row> - -<row> -<entry>User Context B</entry> -<entry>SLI</entry> -<entry>SLI</entry> -<entry>SLBH</entry> -<entry>SLBH</entry> -<entry>SLBH</entry> -<entry>SLBH</entry> -<entry>SLBH</entry> -<entry>SLBH</entry> -<entry>MLI</entry> -<entry>None</entry> -</row> - -</tbody> -</tgroup> -</table> - - <table> -<title>Legend for Locking Requirements Table</title> -<tgroup cols="2"> -<tbody> - -<row> -<entry>SLIS</entry> -<entry>spin_lock_irqsave</entry> -</row> -<row> -<entry>SLI</entry> -<entry>spin_lock_irq</entry> -</row> -<row> -<entry>SL</entry> -<entry>spin_lock</entry> -</row> -<row> -<entry>SLBH</entry> -<entry>spin_lock_bh</entry> -</row> -<row> -<entry>MLI</entry> -<entry>mutex_lock_interruptible</entry> -</row> - -</tbody> -</tgroup> -</table> - -</sect1> -</chapter> - -<chapter id="trylock-functions"> - <title>The trylock Functions</title> - <para> - There are functions that try to acquire a lock only once and immediately - return a value telling about success or failure to acquire the lock. - They can be used if you need no access to the data protected with the lock - when some other thread is holding the lock. You should acquire the lock - later if you then need access to the data protected with the lock. - </para> - - <para> - <function>spin_trylock()</function> does not spin but returns non-zero if - it acquires the spinlock on the first try or 0 if not. This function can - be used in all contexts like <function>spin_lock</function>: you must have - disabled the contexts that might interrupt you and acquire the spin lock. - </para> - - <para> - <function>mutex_trylock()</function> does not suspend your task - but returns non-zero if it could lock the mutex on the first try - or 0 if not. This function cannot be safely used in hardware or software - interrupt contexts despite not sleeping. - </para> -</chapter> - - <chapter id="Examples"> - <title>Common Examples</title> - <para> -Let's step through a simple example: a cache of number to name -mappings. The cache keeps a count of how often each of the objects is -used, and when it gets full, throws out the least used one. - - </para> - - <sect1 id="examples-usercontext"> - <title>All In User Context</title> - <para> -For our first example, we assume that all operations are in user -context (ie. from system calls), so we can sleep. This means we can -use a mutex to protect the cache and all the objects within -it. Here's the code: - </para> - - <programlisting> -#include <linux/list.h> -#include <linux/slab.h> -#include <linux/string.h> -#include <linux/mutex.h> -#include <asm/errno.h> - -struct object -{ - struct list_head list; - int id; - char name[32]; - int popularity; -}; - -/* Protects the cache, cache_num, and the objects within it */ -static DEFINE_MUTEX(cache_lock); -static LIST_HEAD(cache); -static unsigned int cache_num = 0; -#define MAX_CACHE_SIZE 10 - -/* Must be holding cache_lock */ -static struct object *__cache_find(int id) -{ - struct object *i; - - list_for_each_entry(i, &cache, list) - if (i->id == id) { - i->popularity++; - return i; - } - return NULL; -} - -/* Must be holding cache_lock */ -static void __cache_delete(struct object *obj) -{ - BUG_ON(!obj); - list_del(&obj->list); - kfree(obj); - cache_num--; -} - -/* Must be holding cache_lock */ -static void __cache_add(struct object *obj) -{ - list_add(&obj->list, &cache); - if (++cache_num > MAX_CACHE_SIZE) { - struct object *i, *outcast = NULL; - list_for_each_entry(i, &cache, list) { - if (!outcast || i->popularity < outcast->popularity) - outcast = i; - } - __cache_delete(outcast); - } -} - -int cache_add(int id, const char *name) -{ - struct object *obj; - - if ((obj = kmalloc(sizeof(*obj), GFP_KERNEL)) == NULL) - return -ENOMEM; - - strlcpy(obj->name, name, sizeof(obj->name)); - obj->id = id; - obj->popularity = 0; - - mutex_lock(&cache_lock); - __cache_add(obj); - mutex_unlock(&cache_lock); - return 0; -} - -void cache_delete(int id) -{ - mutex_lock(&cache_lock); - __cache_delete(__cache_find(id)); - mutex_unlock(&cache_lock); -} - -int cache_find(int id, char *name) -{ - struct object *obj; - int ret = -ENOENT; - - mutex_lock(&cache_lock); - obj = __cache_find(id); - if (obj) { - ret = 0; - strcpy(name, obj->name); - } - mutex_unlock(&cache_lock); - return ret; -} -</programlisting> - - <para> -Note that we always make sure we have the cache_lock when we add, -delete, or look up the cache: both the cache infrastructure itself and -the contents of the objects are protected by the lock. In this case -it's easy, since we copy the data for the user, and never let them -access the objects directly. - </para> - <para> -There is a slight (and common) optimization here: in -<function>cache_add</function> we set up the fields of the object -before grabbing the lock. This is safe, as no-one else can access it -until we put it in cache. - </para> - </sect1> - - <sect1 id="examples-interrupt"> - <title>Accessing From Interrupt Context</title> - <para> -Now consider the case where <function>cache_find</function> can be -called from interrupt context: either a hardware interrupt or a -softirq. An example would be a timer which deletes object from the -cache. - </para> - <para> -The change is shown below, in standard patch format: the -<symbol>-</symbol> are lines which are taken away, and the -<symbol>+</symbol> are lines which are added. - </para> -<programlisting> ---- cache.c.usercontext 2003-12-09 13:58:54.000000000 +1100 -+++ cache.c.interrupt 2003-12-09 14:07:49.000000000 +1100 -@@ -12,7 +12,7 @@ - int popularity; - }; - --static DEFINE_MUTEX(cache_lock); -+static DEFINE_SPINLOCK(cache_lock); - static LIST_HEAD(cache); - static unsigned int cache_num = 0; - #define MAX_CACHE_SIZE 10 -@@ -55,6 +55,7 @@ - int cache_add(int id, const char *name) - { - struct object *obj; -+ unsigned long flags; - - if ((obj = kmalloc(sizeof(*obj), GFP_KERNEL)) == NULL) - return -ENOMEM; -@@ -63,30 +64,33 @@ - obj->id = id; - obj->popularity = 0; - -- mutex_lock(&cache_lock); -+ spin_lock_irqsave(&cache_lock, flags); - __cache_add(obj); -- mutex_unlock(&cache_lock); -+ spin_unlock_irqrestore(&cache_lock, flags); - return 0; - } - - void cache_delete(int id) - { -- mutex_lock(&cache_lock); -+ unsigned long flags; -+ -+ spin_lock_irqsave(&cache_lock, flags); - __cache_delete(__cache_find(id)); -- mutex_unlock(&cache_lock); -+ spin_unlock_irqrestore(&cache_lock, flags); - } - - int cache_find(int id, char *name) - { - struct object *obj; - int ret = -ENOENT; -+ unsigned long flags; - -- mutex_lock(&cache_lock); -+ spin_lock_irqsave(&cache_lock, flags); - obj = __cache_find(id); - if (obj) { - ret = 0; - strcpy(name, obj->name); - } -- mutex_unlock(&cache_lock); -+ spin_unlock_irqrestore(&cache_lock, flags); - return ret; - } -</programlisting> - - <para> -Note that the <function>spin_lock_irqsave</function> will turn off -interrupts if they are on, otherwise does nothing (if we are already -in an interrupt handler), hence these functions are safe to call from -any context. - </para> - <para> -Unfortunately, <function>cache_add</function> calls -<function>kmalloc</function> with the <symbol>GFP_KERNEL</symbol> -flag, which is only legal in user context. I have assumed that -<function>cache_add</function> is still only called in user context, -otherwise this should become a parameter to -<function>cache_add</function>. - </para> - </sect1> - <sect1 id="examples-refcnt"> - <title>Exposing Objects Outside This File</title> - <para> -If our objects contained more information, it might not be sufficient -to copy the information in and out: other parts of the code might want -to keep pointers to these objects, for example, rather than looking up -the id every time. This produces two problems. - </para> - <para> -The first problem is that we use the <symbol>cache_lock</symbol> to -protect objects: we'd need to make this non-static so the rest of the -code can use it. This makes locking trickier, as it is no longer all -in one place. - </para> - <para> -The second problem is the lifetime problem: if another structure keeps -a pointer to an object, it presumably expects that pointer to remain -valid. Unfortunately, this is only guaranteed while you hold the -lock, otherwise someone might call <function>cache_delete</function> -and even worse, add another object, re-using the same address. - </para> - <para> -As there is only one lock, you can't hold it forever: no-one else would -get any work done. - </para> - <para> -The solution to this problem is to use a reference count: everyone who -has a pointer to the object increases it when they first get the -object, and drops the reference count when they're finished with it. -Whoever drops it to zero knows it is unused, and can actually delete it. - </para> - <para> -Here is the code: - </para> - -<programlisting> ---- cache.c.interrupt 2003-12-09 14:25:43.000000000 +1100 -+++ cache.c.refcnt 2003-12-09 14:33:05.000000000 +1100 -@@ -7,6 +7,7 @@ - struct object - { - struct list_head list; -+ unsigned int refcnt; - int id; - char name[32]; - int popularity; -@@ -17,6 +18,35 @@ - static unsigned int cache_num = 0; - #define MAX_CACHE_SIZE 10 - -+static void __object_put(struct object *obj) -+{ -+ if (--obj->refcnt == 0) -+ kfree(obj); -+} -+ -+static void __object_get(struct object *obj) -+{ -+ obj->refcnt++; -+} -+ -+void object_put(struct object *obj) -+{ -+ unsigned long flags; -+ -+ spin_lock_irqsave(&cache_lock, flags); -+ __object_put(obj); -+ spin_unlock_irqrestore(&cache_lock, flags); -+} -+ -+void object_get(struct object *obj) -+{ -+ unsigned long flags; -+ -+ spin_lock_irqsave(&cache_lock, flags); -+ __object_get(obj); -+ spin_unlock_irqrestore(&cache_lock, flags); -+} -+ - /* Must be holding cache_lock */ - static struct object *__cache_find(int id) - { -@@ -35,6 +65,7 @@ - { - BUG_ON(!obj); - list_del(&obj->list); -+ __object_put(obj); - cache_num--; - } - -@@ -63,6 +94,7 @@ - strlcpy(obj->name, name, sizeof(obj->name)); - obj->id = id; - obj->popularity = 0; -+ obj->refcnt = 1; /* The cache holds a reference */ - - spin_lock_irqsave(&cache_lock, flags); - __cache_add(obj); -@@ -79,18 +111,15 @@ - spin_unlock_irqrestore(&cache_lock, flags); - } - --int cache_find(int id, char *name) -+struct object *cache_find(int id) - { - struct object *obj; -- int ret = -ENOENT; - unsigned long flags; - - spin_lock_irqsave(&cache_lock, flags); - obj = __cache_find(id); -- if (obj) { -- ret = 0; -- strcpy(name, obj->name); -- } -+ if (obj) -+ __object_get(obj); - spin_unlock_irqrestore(&cache_lock, flags); -- return ret; -+ return obj; - } -</programlisting> - -<para> -We encapsulate the reference counting in the standard 'get' and 'put' -functions. Now we can return the object itself from -<function>cache_find</function> which has the advantage that the user -can now sleep holding the object (eg. to -<function>copy_to_user</function> to name to userspace). -</para> -<para> -The other point to note is that I said a reference should be held for -every pointer to the object: thus the reference count is 1 when first -inserted into the cache. In some versions the framework does not hold -a reference count, but they are more complicated. -</para> - - <sect2 id="examples-refcnt-atomic"> - <title>Using Atomic Operations For The Reference Count</title> -<para> -In practice, <type>atomic_t</type> would usually be used for -<structfield>refcnt</structfield>. There are a number of atomic -operations defined in - -<filename class="headerfile">include/asm/atomic.h</filename>: these are -guaranteed to be seen atomically from all CPUs in the system, so no -lock is required. In this case, it is simpler than using spinlocks, -although for anything non-trivial using spinlocks is clearer. The -<function>atomic_inc</function> and -<function>atomic_dec_and_test</function> are used instead of the -standard increment and decrement operators, and the lock is no longer -used to protect the reference count itself. -</para> - -<programlisting> ---- cache.c.refcnt 2003-12-09 15:00:35.000000000 +1100 -+++ cache.c.refcnt-atomic 2003-12-11 15:49:42.000000000 +1100 -@@ -7,7 +7,7 @@ - struct object - { - struct list_head list; -- unsigned int refcnt; -+ atomic_t refcnt; - int id; - char name[32]; - int popularity; -@@ -18,33 +18,15 @@ - static unsigned int cache_num = 0; - #define MAX_CACHE_SIZE 10 - --static void __object_put(struct object *obj) --{ -- if (--obj->refcnt == 0) -- kfree(obj); --} -- --static void __object_get(struct object *obj) --{ -- obj->refcnt++; --} -- - void object_put(struct object *obj) - { -- unsigned long flags; -- -- spin_lock_irqsave(&cache_lock, flags); -- __object_put(obj); -- spin_unlock_irqrestore(&cache_lock, flags); -+ if (atomic_dec_and_test(&obj->refcnt)) -+ kfree(obj); - } - - void object_get(struct object *obj) - { -- unsigned long flags; -- -- spin_lock_irqsave(&cache_lock, flags); -- __object_get(obj); -- spin_unlock_irqrestore(&cache_lock, flags); -+ atomic_inc(&obj->refcnt); - } - - /* Must be holding cache_lock */ -@@ -65,7 +47,7 @@ - { - BUG_ON(!obj); - list_del(&obj->list); -- __object_put(obj); -+ object_put(obj); - cache_num--; - } - -@@ -94,7 +76,7 @@ - strlcpy(obj->name, name, sizeof(obj->name)); - obj->id = id; - obj->popularity = 0; -- obj->refcnt = 1; /* The cache holds a reference */ -+ atomic_set(&obj->refcnt, 1); /* The cache holds a reference */ - - spin_lock_irqsave(&cache_lock, flags); - __cache_add(obj); -@@ -119,7 +101,7 @@ - spin_lock_irqsave(&cache_lock, flags); - obj = __cache_find(id); - if (obj) -- __object_get(obj); -+ object_get(obj); - spin_unlock_irqrestore(&cache_lock, flags); - return obj; - } -</programlisting> -</sect2> -</sect1> - - <sect1 id="examples-lock-per-obj"> - <title>Protecting The Objects Themselves</title> - <para> -In these examples, we assumed that the objects (except the reference -counts) never changed once they are created. If we wanted to allow -the name to change, there are three possibilities: - </para> - <itemizedlist> - <listitem> - <para> -You can make <symbol>cache_lock</symbol> non-static, and tell people -to grab that lock before changing the name in any object. - </para> - </listitem> - <listitem> - <para> -You can provide a <function>cache_obj_rename</function> which grabs -this lock and changes the name for the caller, and tell everyone to -use that function. - </para> - </listitem> - <listitem> - <para> -You can make the <symbol>cache_lock</symbol> protect only the cache -itself, and use another lock to protect the name. - </para> - </listitem> - </itemizedlist> - - <para> -Theoretically, you can make the locks as fine-grained as one lock for -every field, for every object. In practice, the most common variants -are: -</para> - <itemizedlist> - <listitem> - <para> -One lock which protects the infrastructure (the <symbol>cache</symbol> -list in this example) and all the objects. This is what we have done -so far. - </para> - </listitem> - <listitem> - <para> -One lock which protects the infrastructure (including the list -pointers inside the objects), and one lock inside the object which -protects the rest of that object. - </para> - </listitem> - <listitem> - <para> -Multiple locks to protect the infrastructure (eg. one lock per hash -chain), possibly with a separate per-object lock. - </para> - </listitem> - </itemizedlist> - -<para> -Here is the "lock-per-object" implementation: -</para> -<programlisting> ---- cache.c.refcnt-atomic 2003-12-11 15:50:54.000000000 +1100 -+++ cache.c.perobjectlock 2003-12-11 17:15:03.000000000 +1100 -@@ -6,11 +6,17 @@ - - struct object - { -+ /* These two protected by cache_lock. */ - struct list_head list; -+ int popularity; -+ - atomic_t refcnt; -+ -+ /* Doesn't change once created. */ - int id; -+ -+ spinlock_t lock; /* Protects the name */ - char name[32]; -- int popularity; - }; - - static DEFINE_SPINLOCK(cache_lock); -@@ -77,6 +84,7 @@ - obj->id = id; - obj->popularity = 0; - atomic_set(&obj->refcnt, 1); /* The cache holds a reference */ -+ spin_lock_init(&obj->lock); - - spin_lock_irqsave(&cache_lock, flags); - __cache_add(obj); -</programlisting> - -<para> -Note that I decide that the <structfield>popularity</structfield> -count should be protected by the <symbol>cache_lock</symbol> rather -than the per-object lock: this is because it (like the -<structname>struct list_head</structname> inside the object) is -logically part of the infrastructure. This way, I don't need to grab -the lock of every object in <function>__cache_add</function> when -seeking the least popular. -</para> - -<para> -I also decided that the <structfield>id</structfield> member is -unchangeable, so I don't need to grab each object lock in -<function>__cache_find()</function> to examine the -<structfield>id</structfield>: the object lock is only used by a -caller who wants to read or write the <structfield>name</structfield> -field. -</para> - -<para> -Note also that I added a comment describing what data was protected by -which locks. This is extremely important, as it describes the runtime -behavior of the code, and can be hard to gain from just reading. And -as Alan Cox says, <quote>Lock data, not code</quote>. -</para> -</sect1> -</chapter> - - <chapter id="common-problems"> - <title>Common Problems</title> - <sect1 id="deadlock"> - <title>Deadlock: Simple and Advanced</title> - - <para> - There is a coding bug where a piece of code tries to grab a - spinlock twice: it will spin forever, waiting for the lock to - be released (spinlocks, rwlocks and mutexes are not - recursive in Linux). This is trivial to diagnose: not a - stay-up-five-nights-talk-to-fluffy-code-bunnies kind of - problem. - </para> - - <para> - For a slightly more complex case, imagine you have a region - shared by a softirq and user context. If you use a - <function>spin_lock()</function> call to protect it, it is - possible that the user context will be interrupted by the softirq - while it holds the lock, and the softirq will then spin - forever trying to get the same lock. - </para> - - <para> - Both of these are called deadlock, and as shown above, it can - occur even with a single CPU (although not on UP compiles, - since spinlocks vanish on kernel compiles with - <symbol>CONFIG_SMP</symbol>=n. You'll still get data corruption - in the second example). - </para> - - <para> - This complete lockup is easy to diagnose: on SMP boxes the - watchdog timer or compiling with <symbol>DEBUG_SPINLOCK</symbol> set - (<filename>include/linux/spinlock.h</filename>) will show this up - immediately when it happens. - </para> - - <para> - A more complex problem is the so-called 'deadly embrace', - involving two or more locks. Say you have a hash table: each - entry in the table is a spinlock, and a chain of hashed - objects. Inside a softirq handler, you sometimes want to - alter an object from one place in the hash to another: you - grab the spinlock of the old hash chain and the spinlock of - the new hash chain, and delete the object from the old one, - and insert it in the new one. - </para> - - <para> - There are two problems here. First, if your code ever - tries to move the object to the same chain, it will deadlock - with itself as it tries to lock it twice. Secondly, if the - same softirq on another CPU is trying to move another object - in the reverse direction, the following could happen: - </para> - - <table> - <title>Consequences</title> - - <tgroup cols="2" align="left"> - - <thead> - <row> - <entry>CPU 1</entry> - <entry>CPU 2</entry> - </row> - </thead> - - <tbody> - <row> - <entry>Grab lock A -> OK</entry> - <entry>Grab lock B -> OK</entry> - </row> - <row> - <entry>Grab lock B -> spin</entry> - <entry>Grab lock A -> spin</entry> - </row> - </tbody> - </tgroup> - </table> - - <para> - The two CPUs will spin forever, waiting for the other to give up - their lock. It will look, smell, and feel like a crash. - </para> - </sect1> - - <sect1 id="techs-deadlock-prevent"> - <title>Preventing Deadlock</title> - - <para> - Textbooks will tell you that if you always lock in the same - order, you will never get this kind of deadlock. Practice - will tell you that this approach doesn't scale: when I - create a new lock, I don't understand enough of the kernel - to figure out where in the 5000 lock hierarchy it will fit. - </para> - - <para> - The best locks are encapsulated: they never get exposed in - headers, and are never held around calls to non-trivial - functions outside the same file. You can read through this - code and see that it will never deadlock, because it never - tries to grab another lock while it has that one. People - using your code don't even need to know you are using a - lock. - </para> - - <para> - A classic problem here is when you provide callbacks or - hooks: if you call these with the lock held, you risk simple - deadlock, or a deadly embrace (who knows what the callback - will do?). Remember, the other programmers are out to get - you, so don't do this. - </para> - - <sect2 id="techs-deadlock-overprevent"> - <title>Overzealous Prevention Of Deadlocks</title> - - <para> - Deadlocks are problematic, but not as bad as data - corruption. Code which grabs a read lock, searches a list, - fails to find what it wants, drops the read lock, grabs a - write lock and inserts the object has a race condition. - </para> - - <para> - If you don't see why, please stay the fuck away from my code. - </para> - </sect2> - </sect1> - - <sect1 id="racing-timers"> - <title>Racing Timers: A Kernel Pastime</title> - - <para> - Timers can produce their own special problems with races. - Consider a collection of objects (list, hash, etc) where each - object has a timer which is due to destroy it. - </para> - - <para> - If you want to destroy the entire collection (say on module - removal), you might do the following: - </para> - - <programlisting> - /* THIS CODE BAD BAD BAD BAD: IF IT WAS ANY WORSE IT WOULD USE - HUNGARIAN NOTATION */ - spin_lock_bh(&list_lock); - - while (list) { - struct foo *next = list->next; - del_timer(&list->timer); - kfree(list); - list = next; - } - - spin_unlock_bh(&list_lock); - </programlisting> - - <para> - Sooner or later, this will crash on SMP, because a timer can - have just gone off before the <function>spin_lock_bh()</function>, - and it will only get the lock after we - <function>spin_unlock_bh()</function>, and then try to free - the element (which has already been freed!). - </para> - - <para> - This can be avoided by checking the result of - <function>del_timer()</function>: if it returns - <returnvalue>1</returnvalue>, the timer has been deleted. - If <returnvalue>0</returnvalue>, it means (in this - case) that it is currently running, so we can do: - </para> - - <programlisting> - retry: - spin_lock_bh(&list_lock); - - while (list) { - struct foo *next = list->next; - if (!del_timer(&list->timer)) { - /* Give timer a chance to delete this */ - spin_unlock_bh(&list_lock); - goto retry; - } - kfree(list); - list = next; - } - - spin_unlock_bh(&list_lock); - </programlisting> - - <para> - Another common problem is deleting timers which restart - themselves (by calling <function>add_timer()</function> at the end - of their timer function). Because this is a fairly common case - which is prone to races, you should use <function>del_timer_sync()</function> - (<filename class="headerfile">include/linux/timer.h</filename>) - to handle this case. It returns the number of times the timer - had to be deleted before we finally stopped it from adding itself back - in. - </para> - </sect1> - - </chapter> - - <chapter id="Efficiency"> - <title>Locking Speed</title> - - <para> -There are three main things to worry about when considering speed of -some code which does locking. First is concurrency: how many things -are going to be waiting while someone else is holding a lock. Second -is the time taken to actually acquire and release an uncontended lock. -Third is using fewer, or smarter locks. I'm assuming that the lock is -used fairly often: otherwise, you wouldn't be concerned about -efficiency. -</para> - <para> -Concurrency depends on how long the lock is usually held: you should -hold the lock for as long as needed, but no longer. In the cache -example, we always create the object without the lock held, and then -grab the lock only when we are ready to insert it in the list. -</para> - <para> -Acquisition times depend on how much damage the lock operations do to -the pipeline (pipeline stalls) and how likely it is that this CPU was -the last one to grab the lock (ie. is the lock cache-hot for this -CPU): on a machine with more CPUs, this likelihood drops fast. -Consider a 700MHz Intel Pentium III: an instruction takes about 0.7ns, -an atomic increment takes about 58ns, a lock which is cache-hot on -this CPU takes 160ns, and a cacheline transfer from another CPU takes -an additional 170 to 360ns. (These figures from Paul McKenney's -<ulink url="http://www.linuxjournal.com/article.php?sid=6993"> Linux -Journal RCU article</ulink>). -</para> - <para> -These two aims conflict: holding a lock for a short time might be done -by splitting locks into parts (such as in our final per-object-lock -example), but this increases the number of lock acquisitions, and the -results are often slower than having a single lock. This is another -reason to advocate locking simplicity. -</para> - <para> -The third concern is addressed below: there are some methods to reduce -the amount of locking which needs to be done. -</para> - - <sect1 id="efficiency-rwlocks"> - <title>Read/Write Lock Variants</title> - - <para> - Both spinlocks and mutexes have read/write variants: - <type>rwlock_t</type> and <structname>struct rw_semaphore</structname>. - These divide users into two classes: the readers and the writers. If - you are only reading the data, you can get a read lock, but to write to - the data you need the write lock. Many people can hold a read lock, - but a writer must be sole holder. - </para> - - <para> - If your code divides neatly along reader/writer lines (as our - cache code does), and the lock is held by readers for - significant lengths of time, using these locks can help. They - are slightly slower than the normal locks though, so in practice - <type>rwlock_t</type> is not usually worthwhile. - </para> - </sect1> - - <sect1 id="efficiency-read-copy-update"> - <title>Avoiding Locks: Read Copy Update</title> - - <para> - There is a special method of read/write locking called Read Copy - Update. Using RCU, the readers can avoid taking a lock - altogether: as we expect our cache to be read more often than - updated (otherwise the cache is a waste of time), it is a - candidate for this optimization. - </para> - - <para> - How do we get rid of read locks? Getting rid of read locks - means that writers may be changing the list underneath the - readers. That is actually quite simple: we can read a linked - list while an element is being added if the writer adds the - element very carefully. For example, adding - <symbol>new</symbol> to a single linked list called - <symbol>list</symbol>: - </para> - - <programlisting> - new->next = list->next; - wmb(); - list->next = new; - </programlisting> - - <para> - The <function>wmb()</function> is a write memory barrier. It - ensures that the first operation (setting the new element's - <symbol>next</symbol> pointer) is complete and will be seen by - all CPUs, before the second operation is (putting the new - element into the list). This is important, since modern - compilers and modern CPUs can both reorder instructions unless - told otherwise: we want a reader to either not see the new - element at all, or see the new element with the - <symbol>next</symbol> pointer correctly pointing at the rest of - the list. - </para> - <para> - Fortunately, there is a function to do this for standard - <structname>struct list_head</structname> lists: - <function>list_add_rcu()</function> - (<filename>include/linux/list.h</filename>). - </para> - <para> - Removing an element from the list is even simpler: we replace - the pointer to the old element with a pointer to its successor, - and readers will either see it, or skip over it. - </para> - <programlisting> - list->next = old->next; - </programlisting> - <para> - There is <function>list_del_rcu()</function> - (<filename>include/linux/list.h</filename>) which does this (the - normal version poisons the old object, which we don't want). - </para> - <para> - The reader must also be careful: some CPUs can look through the - <symbol>next</symbol> pointer to start reading the contents of - the next element early, but don't realize that the pre-fetched - contents is wrong when the <symbol>next</symbol> pointer changes - underneath them. Once again, there is a - <function>list_for_each_entry_rcu()</function> - (<filename>include/linux/list.h</filename>) to help you. Of - course, writers can just use - <function>list_for_each_entry()</function>, since there cannot - be two simultaneous writers. - </para> - <para> - Our final dilemma is this: when can we actually destroy the - removed element? Remember, a reader might be stepping through - this element in the list right now: if we free this element and - the <symbol>next</symbol> pointer changes, the reader will jump - off into garbage and crash. We need to wait until we know that - all the readers who were traversing the list when we deleted the - element are finished. We use <function>call_rcu()</function> to - register a callback which will actually destroy the object once - all pre-existing readers are finished. Alternatively, - <function>synchronize_rcu()</function> may be used to block until - all pre-existing are finished. - </para> - <para> - But how does Read Copy Update know when the readers are - finished? The method is this: firstly, the readers always - traverse the list inside - <function>rcu_read_lock()</function>/<function>rcu_read_unlock()</function> - pairs: these simply disable preemption so the reader won't go to - sleep while reading the list. - </para> - <para> - RCU then waits until every other CPU has slept at least once: - since readers cannot sleep, we know that any readers which were - traversing the list during the deletion are finished, and the - callback is triggered. The real Read Copy Update code is a - little more optimized than this, but this is the fundamental - idea. - </para> - -<programlisting> ---- cache.c.perobjectlock 2003-12-11 17:15:03.000000000 +1100 -+++ cache.c.rcupdate 2003-12-11 17:55:14.000000000 +1100 -@@ -1,15 +1,18 @@ - #include <linux/list.h> - #include <linux/slab.h> - #include <linux/string.h> -+#include <linux/rcupdate.h> - #include <linux/mutex.h> - #include <asm/errno.h> - - struct object - { -- /* These two protected by cache_lock. */ -+ /* This is protected by RCU */ - struct list_head list; - int popularity; - -+ struct rcu_head rcu; -+ - atomic_t refcnt; - - /* Doesn't change once created. */ -@@ -40,7 +43,7 @@ - { - struct object *i; - -- list_for_each_entry(i, &cache, list) { -+ list_for_each_entry_rcu(i, &cache, list) { - if (i->id == id) { - i->popularity++; - return i; -@@ -49,19 +52,25 @@ - return NULL; - } - -+/* Final discard done once we know no readers are looking. */ -+static void cache_delete_rcu(void *arg) -+{ -+ object_put(arg); -+} -+ - /* Must be holding cache_lock */ - static void __cache_delete(struct object *obj) - { - BUG_ON(!obj); -- list_del(&obj->list); -- object_put(obj); -+ list_del_rcu(&obj->list); - cache_num--; -+ call_rcu(&obj->rcu, cache_delete_rcu); - } - - /* Must be holding cache_lock */ - static void __cache_add(struct object *obj) - { -- list_add(&obj->list, &cache); -+ list_add_rcu(&obj->list, &cache); - if (++cache_num > MAX_CACHE_SIZE) { - struct object *i, *outcast = NULL; - list_for_each_entry(i, &cache, list) { -@@ -104,12 +114,11 @@ - struct object *cache_find(int id) - { - struct object *obj; -- unsigned long flags; - -- spin_lock_irqsave(&cache_lock, flags); -+ rcu_read_lock(); - obj = __cache_find(id); - if (obj) - object_get(obj); -- spin_unlock_irqrestore(&cache_lock, flags); -+ rcu_read_unlock(); - return obj; - } -</programlisting> - -<para> -Note that the reader will alter the -<structfield>popularity</structfield> member in -<function>__cache_find()</function>, and now it doesn't hold a lock. -One solution would be to make it an <type>atomic_t</type>, but for -this usage, we don't really care about races: an approximate result is -good enough, so I didn't change it. -</para> - -<para> -The result is that <function>cache_find()</function> requires no -synchronization with any other functions, so is almost as fast on SMP -as it would be on UP. -</para> - -<para> -There is a further optimization possible here: remember our original -cache code, where there were no reference counts and the caller simply -held the lock whenever using the object? This is still possible: if -you hold the lock, no one can delete the object, so you don't need to -get and put the reference count. -</para> - -<para> -Now, because the 'read lock' in RCU is simply disabling preemption, a -caller which always has preemption disabled between calling -<function>cache_find()</function> and -<function>object_put()</function> does not need to actually get and -put the reference count: we could expose -<function>__cache_find()</function> by making it non-static, and -such callers could simply call that. -</para> -<para> -The benefit here is that the reference count is not written to: the -object is not altered in any way, which is much faster on SMP -machines due to caching. -</para> - </sect1> - - <sect1 id="per-cpu"> - <title>Per-CPU Data</title> - - <para> - Another technique for avoiding locking which is used fairly - widely is to duplicate information for each CPU. For example, - if you wanted to keep a count of a common condition, you could - use a spin lock and a single counter. Nice and simple. - </para> - - <para> - If that was too slow (it's usually not, but if you've got a - really big machine to test on and can show that it is), you - could instead use a counter for each CPU, then none of them need - an exclusive lock. See <function>DEFINE_PER_CPU()</function>, - <function>get_cpu_var()</function> and - <function>put_cpu_var()</function> - (<filename class="headerfile">include/linux/percpu.h</filename>). - </para> - - <para> - Of particular use for simple per-cpu counters is the - <type>local_t</type> type, and the - <function>cpu_local_inc()</function> and related functions, - which are more efficient than simple code on some architectures - (<filename class="headerfile">include/asm/local.h</filename>). - </para> - - <para> - Note that there is no simple, reliable way of getting an exact - value of such a counter, without introducing more locks. This - is not a problem for some uses. - </para> - </sect1> - - <sect1 id="mostly-hardirq"> - <title>Data Which Mostly Used By An IRQ Handler</title> - - <para> - If data is always accessed from within the same IRQ handler, you - don't need a lock at all: the kernel already guarantees that the - irq handler will not run simultaneously on multiple CPUs. - </para> - <para> - Manfred Spraul points out that you can still do this, even if - the data is very occasionally accessed in user context or - softirqs/tasklets. The irq handler doesn't use a lock, and - all other accesses are done as so: - </para> - -<programlisting> - spin_lock(&lock); - disable_irq(irq); - ... - enable_irq(irq); - spin_unlock(&lock); -</programlisting> - <para> - The <function>disable_irq()</function> prevents the irq handler - from running (and waits for it to finish if it's currently - running on other CPUs). The spinlock prevents any other - accesses happening at the same time. Naturally, this is slower - than just a <function>spin_lock_irq()</function> call, so it - only makes sense if this type of access happens extremely - rarely. - </para> - </sect1> - </chapter> - - <chapter id="sleeping-things"> - <title>What Functions Are Safe To Call From Interrupts?</title> - - <para> - Many functions in the kernel sleep (ie. call schedule()) - directly or indirectly: you can never call them while holding a - spinlock, or with preemption disabled. This also means you need - to be in user context: calling them from an interrupt is illegal. - </para> - - <sect1 id="sleeping"> - <title>Some Functions Which Sleep</title> - - <para> - The most common ones are listed below, but you usually have to - read the code to find out if other calls are safe. If everyone - else who calls it can sleep, you probably need to be able to - sleep, too. In particular, registration and deregistration - functions usually expect to be called from user context, and can - sleep. - </para> - - <itemizedlist> - <listitem> - <para> - Accesses to - <firstterm linkend="gloss-userspace">userspace</firstterm>: - </para> - <itemizedlist> - <listitem> - <para> - <function>copy_from_user()</function> - </para> - </listitem> - <listitem> - <para> - <function>copy_to_user()</function> - </para> - </listitem> - <listitem> - <para> - <function>get_user()</function> - </para> - </listitem> - <listitem> - <para> - <function>put_user()</function> - </para> - </listitem> - </itemizedlist> - </listitem> - - <listitem> - <para> - <function>kmalloc(GFP_KERNEL)</function> - </para> - </listitem> - - <listitem> - <para> - <function>mutex_lock_interruptible()</function> and - <function>mutex_lock()</function> - </para> - <para> - There is a <function>mutex_trylock()</function> which does not - sleep. Still, it must not be used inside interrupt context since - its implementation is not safe for that. - <function>mutex_unlock()</function> will also never sleep. - It cannot be used in interrupt context either since a mutex - must be released by the same task that acquired it. - </para> - </listitem> - </itemizedlist> - </sect1> - - <sect1 id="dont-sleep"> - <title>Some Functions Which Don't Sleep</title> - - <para> - Some functions are safe to call from any context, or holding - almost any lock. - </para> - - <itemizedlist> - <listitem> - <para> - <function>printk()</function> - </para> - </listitem> - <listitem> - <para> - <function>kfree()</function> - </para> - </listitem> - <listitem> - <para> - <function>add_timer()</function> and <function>del_timer()</function> - </para> - </listitem> - </itemizedlist> - </sect1> - </chapter> - - <chapter id="apiref-mutex"> - <title>Mutex API reference</title> -!Iinclude/linux/mutex.h -!Ekernel/locking/mutex.c - </chapter> - - <chapter id="apiref-futex"> - <title>Futex API reference</title> -!Ikernel/futex.c - </chapter> - - <chapter id="references"> - <title>Further reading</title> - - <itemizedlist> - <listitem> - <para> - <filename>Documentation/locking/spinlocks.txt</filename>: - Linus Torvalds' spinlocking tutorial in the kernel sources. - </para> - </listitem> - - <listitem> - <para> - Unix Systems for Modern Architectures: Symmetric - Multiprocessing and Caching for Kernel Programmers: - </para> - - <para> - Curt Schimmel's very good introduction to kernel level - locking (not written for Linux, but nearly everything - applies). The book is expensive, but really worth every - penny to understand SMP locking. [ISBN: 0201633388] - </para> - </listitem> - </itemizedlist> - </chapter> - - <chapter id="thanks"> - <title>Thanks</title> - - <para> - Thanks to Telsa Gwynne for DocBooking, neatening and adding - style. - </para> - - <para> - Thanks to Martin Pool, Philipp Rumpf, Stephen Rothwell, Paul - Mackerras, Ruedi Aschwanden, Alan Cox, Manfred Spraul, Tim - Waugh, Pete Zaitcev, James Morris, Robert Love, Paul McKenney, - John Ashby for proofreading, correcting, flaming, commenting. - </para> - - <para> - Thanks to the cabal for having no influence on this document. - </para> - </chapter> - - <glossary id="glossary"> - <title>Glossary</title> - - <glossentry id="gloss-preemption"> - <glossterm>preemption</glossterm> - <glossdef> - <para> - Prior to 2.5, or when <symbol>CONFIG_PREEMPT</symbol> is - unset, processes in user context inside the kernel would not - preempt each other (ie. you had that CPU until you gave it up, - except for interrupts). With the addition of - <symbol>CONFIG_PREEMPT</symbol> in 2.5.4, this changed: when - in user context, higher priority tasks can "cut in": spinlocks - were changed to disable preemption, even on UP. - </para> - </glossdef> - </glossentry> - - <glossentry id="gloss-bh"> - <glossterm>bh</glossterm> - <glossdef> - <para> - Bottom Half: for historical reasons, functions with - '_bh' in them often now refer to any software interrupt, e.g. - <function>spin_lock_bh()</function> blocks any software interrupt - on the current CPU. Bottom halves are deprecated, and will - eventually be replaced by tasklets. Only one bottom half will be - running at any time. - </para> - </glossdef> - </glossentry> - - <glossentry id="gloss-hwinterrupt"> - <glossterm>Hardware Interrupt / Hardware IRQ</glossterm> - <glossdef> - <para> - Hardware interrupt request. <function>in_irq()</function> returns - <returnvalue>true</returnvalue> in a hardware interrupt handler. - </para> - </glossdef> - </glossentry> - - <glossentry id="gloss-interruptcontext"> - <glossterm>Interrupt Context</glossterm> - <glossdef> - <para> - Not user context: processing a hardware irq or software irq. - Indicated by the <function>in_interrupt()</function> macro - returning <returnvalue>true</returnvalue>. - </para> - </glossdef> - </glossentry> - - <glossentry id="gloss-smp"> - <glossterm><acronym>SMP</acronym></glossterm> - <glossdef> - <para> - Symmetric Multi-Processor: kernels compiled for multiple-CPU - machines. (CONFIG_SMP=y). - </para> - </glossdef> - </glossentry> - - <glossentry id="gloss-softirq"> - <glossterm>Software Interrupt / softirq</glossterm> - <glossdef> - <para> - Software interrupt handler. <function>in_irq()</function> returns - <returnvalue>false</returnvalue>; <function>in_softirq()</function> - returns <returnvalue>true</returnvalue>. Tasklets and softirqs - both fall into the category of 'software interrupts'. - </para> - <para> - Strictly speaking a softirq is one of up to 32 enumerated software - interrupts which can run on multiple CPUs at once. - Sometimes used to refer to tasklets as - well (ie. all software interrupts). - </para> - </glossdef> - </glossentry> - - <glossentry id="gloss-tasklet"> - <glossterm>tasklet</glossterm> - <glossdef> - <para> - A dynamically-registrable software interrupt, - which is guaranteed to only run on one CPU at a time. - </para> - </glossdef> - </glossentry> - - <glossentry id="gloss-timers"> - <glossterm>timer</glossterm> - <glossdef> - <para> - A dynamically-registrable software interrupt, which is run at - (or close to) a given time. When running, it is just like a - tasklet (in fact, they are called from the TIMER_SOFTIRQ). - </para> - </glossdef> - </glossentry> - - <glossentry id="gloss-up"> - <glossterm><acronym>UP</acronym></glossterm> - <glossdef> - <para> - Uni-Processor: Non-SMP. (CONFIG_SMP=n). - </para> - </glossdef> - </glossentry> - - <glossentry id="gloss-usercontext"> - <glossterm>User Context</glossterm> - <glossdef> - <para> - The kernel executing on behalf of a particular process (ie. a - system call or trap) or kernel thread. You can tell which - process with the <symbol>current</symbol> macro.) Not to - be confused with userspace. Can be interrupted by software or - hardware interrupts. - </para> - </glossdef> - </glossentry> - - <glossentry id="gloss-userspace"> - <glossterm>Userspace</glossterm> - <glossdef> - <para> - A process executing its own code outside the kernel. - </para> - </glossdef> - </glossentry> - - </glossary> -</book> - diff --git a/Documentation/DocBook/kgdb.tmpl b/Documentation/DocBook/kgdb.tmpl deleted file mode 100644 index 856ac20bf367..000000000000 --- a/Documentation/DocBook/kgdb.tmpl +++ /dev/null @@ -1,918 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="kgdbOnLinux"> - <bookinfo> - <title>Using kgdb, kdb and the kernel debugger internals</title> - - <authorgroup> - <author> - <firstname>Jason</firstname> - <surname>Wessel</surname> - <affiliation> - <address> - <email>jason.wessel@windriver.com</email> - </address> - </affiliation> - </author> - </authorgroup> - <copyright> - <year>2008,2010</year> - <holder>Wind River Systems, Inc.</holder> - </copyright> - <copyright> - <year>2004-2005</year> - <holder>MontaVista Software, Inc.</holder> - </copyright> - <copyright> - <year>2004</year> - <holder>Amit S. Kale</holder> - </copyright> - - <legalnotice> - <para> - This file is licensed under the terms of the GNU General Public License - version 2. This program is licensed "as is" without any warranty of any - kind, whether express or implied. - </para> - - </legalnotice> - </bookinfo> - -<toc></toc> - <chapter id="Introduction"> - <title>Introduction</title> - <para> - The kernel has two different debugger front ends (kdb and kgdb) - which interface to the debug core. It is possible to use either - of the debugger front ends and dynamically transition between them - if you configure the kernel properly at compile and runtime. - </para> - <para> - Kdb is simplistic shell-style interface which you can use on a - system console with a keyboard or serial console. You can use it - to inspect memory, registers, process lists, dmesg, and even set - breakpoints to stop in a certain location. Kdb is not a source - level debugger, although you can set breakpoints and execute some - basic kernel run control. Kdb is mainly aimed at doing some - analysis to aid in development or diagnosing kernel problems. You - can access some symbols by name in kernel built-ins or in kernel - modules if the code was built - with <symbol>CONFIG_KALLSYMS</symbol>. - </para> - <para> - Kgdb is intended to be used as a source level debugger for the - Linux kernel. It is used along with gdb to debug a Linux kernel. - The expectation is that gdb can be used to "break in" to the - kernel to inspect memory, variables and look through call stack - information similar to the way an application developer would use - gdb to debug an application. It is possible to place breakpoints - in kernel code and perform some limited execution stepping. - </para> - <para> - Two machines are required for using kgdb. One of these machines is - a development machine and the other is the target machine. The - kernel to be debugged runs on the target machine. The development - machine runs an instance of gdb against the vmlinux file which - contains the symbols (not a boot image such as bzImage, zImage, - uImage...). In gdb the developer specifies the connection - parameters and connects to kgdb. The type of connection a - developer makes with gdb depends on the availability of kgdb I/O - modules compiled as built-ins or loadable kernel modules in the test - machine's kernel. - </para> - </chapter> - <chapter id="CompilingAKernel"> - <title>Compiling a kernel</title> - <para> - <itemizedlist> - <listitem><para>In order to enable compilation of kdb, you must first enable kgdb.</para></listitem> - <listitem><para>The kgdb test compile options are described in the kgdb test suite chapter.</para></listitem> - </itemizedlist> - </para> - <sect1 id="CompileKGDB"> - <title>Kernel config options for kgdb</title> - <para> - To enable <symbol>CONFIG_KGDB</symbol> you should look under - "Kernel hacking" / "Kernel debugging" and select "KGDB: kernel debugger". - </para> - <para> - While it is not a hard requirement that you have symbols in your - vmlinux file, gdb tends not to be very useful without the symbolic - data, so you will want to turn - on <symbol>CONFIG_DEBUG_INFO</symbol> which is called "Compile the - kernel with debug info" in the config menu. - </para> - <para> - It is advised, but not required, that you turn on the - <symbol>CONFIG_FRAME_POINTER</symbol> kernel option which is called "Compile the - kernel with frame pointers" in the config menu. This option - inserts code to into the compiled executable which saves the frame - information in registers or on the stack at different points which - allows a debugger such as gdb to more accurately construct - stack back traces while debugging the kernel. - </para> - <para> - If the architecture that you are using supports the kernel option - CONFIG_STRICT_KERNEL_RWX, you should consider turning it off. This - option will prevent the use of software breakpoints because it - marks certain regions of the kernel's memory space as read-only. - If kgdb supports it for the architecture you are using, you can - use hardware breakpoints if you desire to run with the - CONFIG_STRICT_KERNEL_RWX option turned on, else you need to turn off - this option. - </para> - <para> - Next you should choose one of more I/O drivers to interconnect - debugging host and debugged target. Early boot debugging requires - a KGDB I/O driver that supports early debugging and the driver - must be built into the kernel directly. Kgdb I/O driver - configuration takes place via kernel or module parameters which - you can learn more about in the in the section that describes the - parameter "kgdboc". - </para> - <para>Here is an example set of .config symbols to enable or - disable for kgdb: - <itemizedlist> - <listitem><para># CONFIG_STRICT_KERNEL_RWX is not set</para></listitem> - <listitem><para>CONFIG_FRAME_POINTER=y</para></listitem> - <listitem><para>CONFIG_KGDB=y</para></listitem> - <listitem><para>CONFIG_KGDB_SERIAL_CONSOLE=y</para></listitem> - </itemizedlist> - </para> - </sect1> - <sect1 id="CompileKDB"> - <title>Kernel config options for kdb</title> - <para>Kdb is quite a bit more complex than the simple gdbstub - sitting on top of the kernel's debug core. Kdb must implement a - shell, and also adds some helper functions in other parts of the - kernel, responsible for printing out interesting data such as what - you would see if you ran "lsmod", or "ps". In order to build kdb - into the kernel you follow the same steps as you would for kgdb. - </para> - <para>The main config option for kdb - is <symbol>CONFIG_KGDB_KDB</symbol> which is called "KGDB_KDB: - include kdb frontend for kgdb" in the config menu. In theory you - would have already also selected an I/O driver such as the - CONFIG_KGDB_SERIAL_CONSOLE interface if you plan on using kdb on a - serial port, when you were configuring kgdb. - </para> - <para>If you want to use a PS/2-style keyboard with kdb, you would - select CONFIG_KDB_KEYBOARD which is called "KGDB_KDB: keyboard as - input device" in the config menu. The CONFIG_KDB_KEYBOARD option - is not used for anything in the gdb interface to kgdb. The - CONFIG_KDB_KEYBOARD option only works with kdb. - </para> - <para>Here is an example set of .config symbols to enable/disable kdb: - <itemizedlist> - <listitem><para># CONFIG_STRICT_KERNEL_RWX is not set</para></listitem> - <listitem><para>CONFIG_FRAME_POINTER=y</para></listitem> - <listitem><para>CONFIG_KGDB=y</para></listitem> - <listitem><para>CONFIG_KGDB_SERIAL_CONSOLE=y</para></listitem> - <listitem><para>CONFIG_KGDB_KDB=y</para></listitem> - <listitem><para>CONFIG_KDB_KEYBOARD=y</para></listitem> - </itemizedlist> - </para> - </sect1> - </chapter> - <chapter id="kgdbKernelArgs"> - <title>Kernel Debugger Boot Arguments</title> - <para>This section describes the various runtime kernel - parameters that affect the configuration of the kernel debugger. - The following chapter covers using kdb and kgdb as well as - providing some examples of the configuration parameters.</para> - <sect1 id="kgdboc"> - <title>Kernel parameter: kgdboc</title> - <para>The kgdboc driver was originally an abbreviation meant to - stand for "kgdb over console". Today it is the primary mechanism - to configure how to communicate from gdb to kgdb as well as the - devices you want to use to interact with the kdb shell. - </para> - <para>For kgdb/gdb, kgdboc is designed to work with a single serial - port. It is intended to cover the circumstance where you want to - use a serial console as your primary console as well as using it to - perform kernel debugging. It is also possible to use kgdb on a - serial port which is not designated as a system console. Kgdboc - may be configured as a kernel built-in or a kernel loadable module. - You can only make use of <constant>kgdbwait</constant> and early - debugging if you build kgdboc into the kernel as a built-in. - </para> - <para>Optionally you can elect to activate kms (Kernel Mode - Setting) integration. When you use kms with kgdboc and you have a - video driver that has atomic mode setting hooks, it is possible to - enter the debugger on the graphics console. When the kernel - execution is resumed, the previous graphics mode will be restored. - This integration can serve as a useful tool to aid in diagnosing - crashes or doing analysis of memory with kdb while allowing the - full graphics console applications to run. - </para> - <sect2 id="kgdbocArgs"> - <title>kgdboc arguments</title> - <para>Usage: <constant>kgdboc=[kms][[,]kbd][[,]serial_device][,baud]</constant></para> - <para>The order listed above must be observed if you use any of the - optional configurations together. - </para> - <para>Abbreviations: - <itemizedlist> - <listitem><para>kms = Kernel Mode Setting</para></listitem> - <listitem><para>kbd = Keyboard</para></listitem> - </itemizedlist> - </para> - <para>You can configure kgdboc to use the keyboard, and/or a serial - device depending on if you are using kdb and/or kgdb, in one of the - following scenarios. The order listed above must be observed if - you use any of the optional configurations together. Using kms + - only gdb is generally not a useful combination.</para> - <sect3 id="kgdbocArgs1"> - <title>Using loadable module or built-in</title> - <para> - <orderedlist> - <listitem><para>As a kernel built-in:</para> - <para>Use the kernel boot argument: <constant>kgdboc=<tty-device>,[baud]</constant></para></listitem> - <listitem> - <para>As a kernel loadable module:</para> - <para>Use the command: <constant>modprobe kgdboc kgdboc=<tty-device>,[baud]</constant></para> - <para>Here are two examples of how you might format the kgdboc - string. The first is for an x86 target using the first serial port. - The second example is for the ARM Versatile AB using the second - serial port. - <orderedlist> - <listitem><para><constant>kgdboc=ttyS0,115200</constant></para></listitem> - <listitem><para><constant>kgdboc=ttyAMA1,115200</constant></para></listitem> - </orderedlist> - </para> - </listitem> - </orderedlist></para> - </sect3> - <sect3 id="kgdbocArgs2"> - <title>Configure kgdboc at runtime with sysfs</title> - <para>At run time you can enable or disable kgdboc by echoing a - parameters into the sysfs. Here are two examples:</para> - <orderedlist> - <listitem><para>Enable kgdboc on ttyS0</para> - <para><constant>echo ttyS0 > /sys/module/kgdboc/parameters/kgdboc</constant></para></listitem> - <listitem><para>Disable kgdboc</para> - <para><constant>echo "" > /sys/module/kgdboc/parameters/kgdboc</constant></para></listitem> - </orderedlist> - <para>NOTE: You do not need to specify the baud if you are - configuring the console on tty which is already configured or - open.</para> - </sect3> - <sect3 id="kgdbocArgs3"> - <title>More examples</title> - <para>You can configure kgdboc to use the keyboard, and/or a serial device - depending on if you are using kdb and/or kgdb, in one of the - following scenarios. - <orderedlist> - <listitem><para>kdb and kgdb over only a serial port</para> - <para><constant>kgdboc=<serial_device>[,baud]</constant></para> - <para>Example: <constant>kgdboc=ttyS0,115200</constant></para> - </listitem> - <listitem><para>kdb and kgdb with keyboard and a serial port</para> - <para><constant>kgdboc=kbd,<serial_device>[,baud]</constant></para> - <para>Example: <constant>kgdboc=kbd,ttyS0,115200</constant></para> - </listitem> - <listitem><para>kdb with a keyboard</para> - <para><constant>kgdboc=kbd</constant></para> - </listitem> - <listitem><para>kdb with kernel mode setting</para> - <para><constant>kgdboc=kms,kbd</constant></para> - </listitem> - <listitem><para>kdb with kernel mode setting and kgdb over a serial port</para> - <para><constant>kgdboc=kms,kbd,ttyS0,115200</constant></para> - </listitem> - </orderedlist> - </para> - <para>NOTE: Kgdboc does not support interrupting the target via the - gdb remote protocol. You must manually send a sysrq-g unless you - have a proxy that splits console output to a terminal program. - A console proxy has a separate TCP port for the debugger and a separate - TCP port for the "human" console. The proxy can take care of sending - the sysrq-g for you. - </para> - <para>When using kgdboc with no debugger proxy, you can end up - connecting the debugger at one of two entry points. If an - exception occurs after you have loaded kgdboc, a message should - print on the console stating it is waiting for the debugger. In - this case you disconnect your terminal program and then connect the - debugger in its place. If you want to interrupt the target system - and forcibly enter a debug session you have to issue a Sysrq - sequence and then type the letter <constant>g</constant>. Then - you disconnect the terminal session and connect gdb. Your options - if you don't like this are to hack gdb to send the sysrq-g for you - as well as on the initial connect, or to use a debugger proxy that - allows an unmodified gdb to do the debugging. - </para> - </sect3> - </sect2> - </sect1> - <sect1 id="kgdbwait"> - <title>Kernel parameter: kgdbwait</title> - <para> - The Kernel command line option <constant>kgdbwait</constant> makes - kgdb wait for a debugger connection during booting of a kernel. You - can only use this option if you compiled a kgdb I/O driver into the - kernel and you specified the I/O driver configuration as a kernel - command line option. The kgdbwait parameter should always follow the - configuration parameter for the kgdb I/O driver in the kernel - command line else the I/O driver will not be configured prior to - asking the kernel to use it to wait. - </para> - <para> - The kernel will stop and wait as early as the I/O driver and - architecture allows when you use this option. If you build the - kgdb I/O driver as a loadable kernel module kgdbwait will not do - anything. - </para> - </sect1> - <sect1 id="kgdbcon"> - <title>Kernel parameter: kgdbcon</title> - <para> The kgdbcon feature allows you to see printk() messages - inside gdb while gdb is connected to the kernel. Kdb does not make - use of the kgdbcon feature. - </para> - <para>Kgdb supports using the gdb serial protocol to send console - messages to the debugger when the debugger is connected and running. - There are two ways to activate this feature. - <orderedlist> - <listitem><para>Activate with the kernel command line option:</para> - <para><constant>kgdbcon</constant></para> - </listitem> - <listitem><para>Use sysfs before configuring an I/O driver</para> - <para> - <constant>echo 1 > /sys/module/kgdb/parameters/kgdb_use_con</constant> - </para> - <para> - NOTE: If you do this after you configure the kgdb I/O driver, the - setting will not take effect until the next point the I/O is - reconfigured. - </para> - </listitem> - </orderedlist> - </para> - <para>IMPORTANT NOTE: You cannot use kgdboc + kgdbcon on a tty that is an - active system console. An example of incorrect usage is <constant>console=ttyS0,115200 kgdboc=ttyS0 kgdbcon</constant> - </para> - <para>It is possible to use this option with kgdboc on a tty that is not a system console. - </para> - </sect1> - <sect1 id="kgdbreboot"> - <title>Run time parameter: kgdbreboot</title> - <para> The kgdbreboot feature allows you to change how the debugger - deals with the reboot notification. You have 3 choices for the - behavior. The default behavior is always set to 0.</para> - <orderedlist> - <listitem><para>echo -1 > /sys/module/debug_core/parameters/kgdbreboot</para> - <para>Ignore the reboot notification entirely.</para> - </listitem> - <listitem><para>echo 0 > /sys/module/debug_core/parameters/kgdbreboot</para> - <para>Send the detach message to any attached debugger client.</para> - </listitem> - <listitem><para>echo 1 > /sys/module/debug_core/parameters/kgdbreboot</para> - <para>Enter the debugger on reboot notify.</para> - </listitem> - </orderedlist> - </sect1> - </chapter> - <chapter id="usingKDB"> - <title>Using kdb</title> - <para> - </para> - <sect1 id="quickKDBserial"> - <title>Quick start for kdb on a serial port</title> - <para>This is a quick example of how to use kdb.</para> - <para><orderedlist> - <listitem><para>Configure kgdboc at boot using kernel parameters: - <itemizedlist> - <listitem><para><constant>console=ttyS0,115200 kgdboc=ttyS0,115200</constant></para></listitem> - </itemizedlist></para> - <para>OR</para> - <para>Configure kgdboc after the kernel has booted; assuming you are using a serial port console: - <itemizedlist> - <listitem><para><constant>echo ttyS0 > /sys/module/kgdboc/parameters/kgdboc</constant></para></listitem> - </itemizedlist> - </para> - </listitem> - <listitem><para>Enter the kernel debugger manually or by waiting for an oops or fault. There are several ways you can enter the kernel debugger manually; all involve using the sysrq-g, which means you must have enabled CONFIG_MAGIC_SYSRQ=y in your kernel config.</para> - <itemizedlist> - <listitem><para>When logged in as root or with a super user session you can run:</para> - <para><constant>echo g > /proc/sysrq-trigger</constant></para></listitem> - <listitem><para>Example using minicom 2.2</para> - <para>Press: <constant>Control-a</constant></para> - <para>Press: <constant>f</constant></para> - <para>Press: <constant>g</constant></para> - </listitem> - <listitem><para>When you have telneted to a terminal server that supports sending a remote break</para> - <para>Press: <constant>Control-]</constant></para> - <para>Type in:<constant>send break</constant></para> - <para>Press: <constant>Enter</constant></para> - <para>Press: <constant>g</constant></para> - </listitem> - </itemizedlist> - </listitem> - <listitem><para>From the kdb prompt you can run the "help" command to see a complete list of the commands that are available.</para> - <para>Some useful commands in kdb include: - <itemizedlist> - <listitem><para>lsmod -- Shows where kernel modules are loaded</para></listitem> - <listitem><para>ps -- Displays only the active processes</para></listitem> - <listitem><para>ps A -- Shows all the processes</para></listitem> - <listitem><para>summary -- Shows kernel version info and memory usage</para></listitem> - <listitem><para>bt -- Get a backtrace of the current process using dump_stack()</para></listitem> - <listitem><para>dmesg -- View the kernel syslog buffer</para></listitem> - <listitem><para>go -- Continue the system</para></listitem> - </itemizedlist> - </para> - </listitem> - <listitem> - <para>When you are done using kdb you need to consider rebooting the - system or using the "go" command to resuming normal kernel - execution. If you have paused the kernel for a lengthy period of - time, applications that rely on timely networking or anything to do - with real wall clock time could be adversely affected, so you - should take this into consideration when using the kernel - debugger.</para> - </listitem> - </orderedlist></para> - </sect1> - <sect1 id="quickKDBkeyboard"> - <title>Quick start for kdb using a keyboard connected console</title> - <para>This is a quick example of how to use kdb with a keyboard.</para> - <para><orderedlist> - <listitem><para>Configure kgdboc at boot using kernel parameters: - <itemizedlist> - <listitem><para><constant>kgdboc=kbd</constant></para></listitem> - </itemizedlist></para> - <para>OR</para> - <para>Configure kgdboc after the kernel has booted: - <itemizedlist> - <listitem><para><constant>echo kbd > /sys/module/kgdboc/parameters/kgdboc</constant></para></listitem> - </itemizedlist> - </para> - </listitem> - <listitem><para>Enter the kernel debugger manually or by waiting for an oops or fault. There are several ways you can enter the kernel debugger manually; all involve using the sysrq-g, which means you must have enabled CONFIG_MAGIC_SYSRQ=y in your kernel config.</para> - <itemizedlist> - <listitem><para>When logged in as root or with a super user session you can run:</para> - <para><constant>echo g > /proc/sysrq-trigger</constant></para></listitem> - <listitem><para>Example using a laptop keyboard</para> - <para>Press and hold down: <constant>Alt</constant></para> - <para>Press and hold down: <constant>Fn</constant></para> - <para>Press and release the key with the label: <constant>SysRq</constant></para> - <para>Release: <constant>Fn</constant></para> - <para>Press and release: <constant>g</constant></para> - <para>Release: <constant>Alt</constant></para> - </listitem> - <listitem><para>Example using a PS/2 101-key keyboard</para> - <para>Press and hold down: <constant>Alt</constant></para> - <para>Press and release the key with the label: <constant>SysRq</constant></para> - <para>Press and release: <constant>g</constant></para> - <para>Release: <constant>Alt</constant></para> - </listitem> - </itemizedlist> - </listitem> - <listitem> - <para>Now type in a kdb command such as "help", "dmesg", "bt" or "go" to continue kernel execution.</para> - </listitem> - </orderedlist></para> - </sect1> - </chapter> - <chapter id="EnableKGDB"> - <title>Using kgdb / gdb</title> - <para>In order to use kgdb you must activate it by passing - configuration information to one of the kgdb I/O drivers. If you - do not pass any configuration information kgdb will not do anything - at all. Kgdb will only actively hook up to the kernel trap hooks - if a kgdb I/O driver is loaded and configured. If you unconfigure - a kgdb I/O driver, kgdb will unregister all the kernel hook points. - </para> - <para> All kgdb I/O drivers can be reconfigured at run time, if - <symbol>CONFIG_SYSFS</symbol> and <symbol>CONFIG_MODULES</symbol> - are enabled, by echo'ing a new config string to - <constant>/sys/module/<driver>/parameter/<option></constant>. - The driver can be unconfigured by passing an empty string. You cannot - change the configuration while the debugger is attached. Make sure - to detach the debugger with the <constant>detach</constant> command - prior to trying to unconfigure a kgdb I/O driver. - </para> - <sect1 id="ConnectingGDB"> - <title>Connecting with gdb to a serial port</title> - <orderedlist> - <listitem><para>Configure kgdboc</para> - <para>Configure kgdboc at boot using kernel parameters: - <itemizedlist> - <listitem><para><constant>kgdboc=ttyS0,115200</constant></para></listitem> - </itemizedlist></para> - <para>OR</para> - <para>Configure kgdboc after the kernel has booted: - <itemizedlist> - <listitem><para><constant>echo ttyS0 > /sys/module/kgdboc/parameters/kgdboc</constant></para></listitem> - </itemizedlist></para> - </listitem> - <listitem> - <para>Stop kernel execution (break into the debugger)</para> - <para>In order to connect to gdb via kgdboc, the kernel must - first be stopped. There are several ways to stop the kernel which - include using kgdbwait as a boot argument, via a sysrq-g, or running - the kernel until it takes an exception where it waits for the - debugger to attach. - <itemizedlist> - <listitem><para>When logged in as root or with a super user session you can run:</para> - <para><constant>echo g > /proc/sysrq-trigger</constant></para></listitem> - <listitem><para>Example using minicom 2.2</para> - <para>Press: <constant>Control-a</constant></para> - <para>Press: <constant>f</constant></para> - <para>Press: <constant>g</constant></para> - </listitem> - <listitem><para>When you have telneted to a terminal server that supports sending a remote break</para> - <para>Press: <constant>Control-]</constant></para> - <para>Type in:<constant>send break</constant></para> - <para>Press: <constant>Enter</constant></para> - <para>Press: <constant>g</constant></para> - </listitem> - </itemizedlist> - </para> - </listitem> - <listitem> - <para>Connect from gdb</para> - <para> - Example (using a directly connected port): - </para> - <programlisting> - % gdb ./vmlinux - (gdb) set remotebaud 115200 - (gdb) target remote /dev/ttyS0 - </programlisting> - <para> - Example (kgdb to a terminal server on TCP port 2012): - </para> - <programlisting> - % gdb ./vmlinux - (gdb) target remote 192.168.2.2:2012 - </programlisting> - <para> - Once connected, you can debug a kernel the way you would debug an - application program. - </para> - <para> - If you are having problems connecting or something is going - seriously wrong while debugging, it will most often be the case - that you want to enable gdb to be verbose about its target - communications. You do this prior to issuing the <constant>target - remote</constant> command by typing in: <constant>set debug remote 1</constant> - </para> - </listitem> - </orderedlist> - <para>Remember if you continue in gdb, and need to "break in" again, - you need to issue an other sysrq-g. It is easy to create a simple - entry point by putting a breakpoint at <constant>sys_sync</constant> - and then you can run "sync" from a shell or script to break into the - debugger.</para> - </sect1> - </chapter> - <chapter id="switchKdbKgdb"> - <title>kgdb and kdb interoperability</title> - <para>It is possible to transition between kdb and kgdb dynamically. - The debug core will remember which you used the last time and - automatically start in the same mode.</para> - <sect1> - <title>Switching between kdb and kgdb</title> - <sect2> - <title>Switching from kgdb to kdb</title> - <para> - There are two ways to switch from kgdb to kdb: you can use gdb to - issue a maintenance packet, or you can blindly type the command $3#33. - Whenever the kernel debugger stops in kgdb mode it will print the - message <constant>KGDB or $3#33 for KDB</constant>. It is important - to note that you have to type the sequence correctly in one pass. - You cannot type a backspace or delete because kgdb will interpret - that as part of the debug stream. - <orderedlist> - <listitem><para>Change from kgdb to kdb by blindly typing:</para> - <para><constant>$3#33</constant></para></listitem> - <listitem><para>Change from kgdb to kdb with gdb</para> - <para><constant>maintenance packet 3</constant></para> - <para>NOTE: Now you must kill gdb. Typically you press control-z and - issue the command: kill -9 %</para></listitem> - </orderedlist> - </para> - </sect2> - <sect2> - <title>Change from kdb to kgdb</title> - <para>There are two ways you can change from kdb to kgdb. You can - manually enter kgdb mode by issuing the kgdb command from the kdb - shell prompt, or you can connect gdb while the kdb shell prompt is - active. The kdb shell looks for the typical first commands that gdb - would issue with the gdb remote protocol and if it sees one of those - commands it automatically changes into kgdb mode.</para> - <orderedlist> - <listitem><para>From kdb issue the command:</para> - <para><constant>kgdb</constant></para> - <para>Now disconnect your terminal program and connect gdb in its place</para></listitem> - <listitem><para>At the kdb prompt, disconnect the terminal program and connect gdb in its place.</para></listitem> - </orderedlist> - </sect2> - </sect1> - <sect1> - <title>Running kdb commands from gdb</title> - <para>It is possible to run a limited set of kdb commands from gdb, - using the gdb monitor command. You don't want to execute any of the - run control or breakpoint operations, because it can disrupt the - state of the kernel debugger. You should be using gdb for - breakpoints and run control operations if you have gdb connected. - The more useful commands to run are things like lsmod, dmesg, ps or - possibly some of the memory information commands. To see all the kdb - commands you can run <constant>monitor help</constant>.</para> - <para>Example: - <informalexample><programlisting> -(gdb) monitor ps -1 idle process (state I) and -27 sleeping system daemon (state M) processes suppressed, -use 'ps A' to see all. -Task Addr Pid Parent [*] cpu State Thread Command - -0xc78291d0 1 0 0 0 S 0xc7829404 init -0xc7954150 942 1 0 0 S 0xc7954384 dropbear -0xc78789c0 944 1 0 0 S 0xc7878bf4 sh -(gdb) - </programlisting></informalexample> - </para> - </sect1> - </chapter> - <chapter id="KGDBTestSuite"> - <title>kgdb Test Suite</title> - <para> - When kgdb is enabled in the kernel config you can also elect to - enable the config parameter KGDB_TESTS. Turning this on will - enable a special kgdb I/O module which is designed to test the - kgdb internal functions. - </para> - <para> - The kgdb tests are mainly intended for developers to test the kgdb - internals as well as a tool for developing a new kgdb architecture - specific implementation. These tests are not really for end users - of the Linux kernel. The primary source of documentation would be - to look in the drivers/misc/kgdbts.c file. - </para> - <para> - The kgdb test suite can also be configured at compile time to run - the core set of tests by setting the kernel config parameter - KGDB_TESTS_ON_BOOT. This particular option is aimed at automated - regression testing and does not require modifying the kernel boot - config arguments. If this is turned on, the kgdb test suite can - be disabled by specifying "kgdbts=" as a kernel boot argument. - </para> - </chapter> - <chapter id="CommonBackEndReq"> - <title>Kernel Debugger Internals</title> - <sect1 id="kgdbArchitecture"> - <title>Architecture Specifics</title> - <para> - The kernel debugger is organized into a number of components: - <orderedlist> - <listitem><para>The debug core</para> - <para> - The debug core is found in kernel/debugger/debug_core.c. It contains: - <itemizedlist> - <listitem><para>A generic OS exception handler which includes - sync'ing the processors into a stopped state on an multi-CPU - system.</para></listitem> - <listitem><para>The API to talk to the kgdb I/O drivers</para></listitem> - <listitem><para>The API to make calls to the arch-specific kgdb implementation</para></listitem> - <listitem><para>The logic to perform safe memory reads and writes to memory while using the debugger</para></listitem> - <listitem><para>A full implementation for software breakpoints unless overridden by the arch</para></listitem> - <listitem><para>The API to invoke either the kdb or kgdb frontend to the debug core.</para></listitem> - <listitem><para>The structures and callback API for atomic kernel mode setting.</para> - <para>NOTE: kgdboc is where the kms callbacks are invoked.</para></listitem> - </itemizedlist> - </para> - </listitem> - <listitem><para>kgdb arch-specific implementation</para> - <para> - This implementation is generally found in arch/*/kernel/kgdb.c. - As an example, arch/x86/kernel/kgdb.c contains the specifics to - implement HW breakpoint as well as the initialization to - dynamically register and unregister for the trap handlers on - this architecture. The arch-specific portion implements: - <itemizedlist> - <listitem><para>contains an arch-specific trap catcher which - invokes kgdb_handle_exception() to start kgdb about doing its - work</para></listitem> - <listitem><para>translation to and from gdb specific packet format to pt_regs</para></listitem> - <listitem><para>Registration and unregistration of architecture specific trap hooks</para></listitem> - <listitem><para>Any special exception handling and cleanup</para></listitem> - <listitem><para>NMI exception handling and cleanup</para></listitem> - <listitem><para>(optional) HW breakpoints</para></listitem> - </itemizedlist> - </para> - </listitem> - <listitem><para>gdbstub frontend (aka kgdb)</para> - <para>The gdbstub is located in kernel/debug/gdbstub.c. It contains:</para> - <itemizedlist> - <listitem><para>All the logic to implement the gdb serial protocol</para></listitem> - </itemizedlist> - </listitem> - <listitem><para>kdb frontend</para> - <para>The kdb debugger shell is broken down into a number of - components. The kdb core is located in kernel/debug/kdb. There - are a number of helper functions in some of the other kernel - components to make it possible for kdb to examine and report - information about the kernel without taking locks that could - cause a kernel deadlock. The kdb core contains implements the following functionality.</para> - <itemizedlist> - <listitem><para>A simple shell</para></listitem> - <listitem><para>The kdb core command set</para></listitem> - <listitem><para>A registration API to register additional kdb shell commands.</para> - <itemizedlist> - <listitem><para>A good example of a self-contained kdb module - is the "ftdump" command for dumping the ftrace buffer. See: - kernel/trace/trace_kdb.c</para></listitem> - <listitem><para>For an example of how to dynamically register - a new kdb command you can build the kdb_hello.ko kernel module - from samples/kdb/kdb_hello.c. To build this example you can - set CONFIG_SAMPLES=y and CONFIG_SAMPLE_KDB=m in your kernel - config. Later run "modprobe kdb_hello" and the next time you - enter the kdb shell, you can run the "hello" - command.</para></listitem> - </itemizedlist></listitem> - <listitem><para>The implementation for kdb_printf() which - emits messages directly to I/O drivers, bypassing the kernel - log.</para></listitem> - <listitem><para>SW / HW breakpoint management for the kdb shell</para></listitem> - </itemizedlist> - </listitem> - <listitem><para>kgdb I/O driver</para> - <para> - Each kgdb I/O driver has to provide an implementation for the following: - <itemizedlist> - <listitem><para>configuration via built-in or module</para></listitem> - <listitem><para>dynamic configuration and kgdb hook registration calls</para></listitem> - <listitem><para>read and write character interface</para></listitem> - <listitem><para>A cleanup handler for unconfiguring from the kgdb core</para></listitem> - <listitem><para>(optional) Early debug methodology</para></listitem> - </itemizedlist> - Any given kgdb I/O driver has to operate very closely with the - hardware and must do it in such a way that does not enable - interrupts or change other parts of the system context without - completely restoring them. The kgdb core will repeatedly "poll" - a kgdb I/O driver for characters when it needs input. The I/O - driver is expected to return immediately if there is no data - available. Doing so allows for the future possibility to touch - watchdog hardware in such a way as to have a target system not - reset when these are enabled. - </para> - </listitem> - </orderedlist> - </para> - <para> - If you are intent on adding kgdb architecture specific support - for a new architecture, the architecture should define - <constant>HAVE_ARCH_KGDB</constant> in the architecture specific - Kconfig file. This will enable kgdb for the architecture, and - at that point you must create an architecture specific kgdb - implementation. - </para> - <para> - There are a few flags which must be set on every architecture in - their <asm/kgdb.h> file. These are: - <itemizedlist> - <listitem> - <para> - NUMREGBYTES: The size in bytes of all of the registers, so - that we can ensure they will all fit into a packet. - </para> - </listitem> - <listitem> - <para> - BUFMAX: The size in bytes of the buffer GDB will read into. - This must be larger than NUMREGBYTES. - </para> - </listitem> - <listitem> - <para> - CACHE_FLUSH_IS_SAFE: Set to 1 if it is always safe to call - flush_cache_range or flush_icache_range. On some architectures, - these functions may not be safe to call on SMP since we keep other - CPUs in a holding pattern. - </para> - </listitem> - </itemizedlist> - </para> - <para> - There are also the following functions for the common backend, - found in kernel/kgdb.c, that must be supplied by the - architecture-specific backend unless marked as (optional), in - which case a default function maybe used if the architecture - does not need to provide a specific implementation. - </para> -!Iinclude/linux/kgdb.h - </sect1> - <sect1 id="kgdbocDesign"> - <title>kgdboc internals</title> - <sect2> - <title>kgdboc and uarts</title> - <para> - The kgdboc driver is actually a very thin driver that relies on the - underlying low level to the hardware driver having "polling hooks" - to which the tty driver is attached. In the initial - implementation of kgdboc the serial_core was changed to expose a - low level UART hook for doing polled mode reading and writing of a - single character while in an atomic context. When kgdb makes an I/O - request to the debugger, kgdboc invokes a callback in the serial - core which in turn uses the callback in the UART driver.</para> - <para> - When using kgdboc with a UART, the UART driver must implement two callbacks in the <constant>struct uart_ops</constant>. Example from drivers/8250.c:<programlisting> -#ifdef CONFIG_CONSOLE_POLL - .poll_get_char = serial8250_get_poll_char, - .poll_put_char = serial8250_put_poll_char, -#endif - </programlisting> - Any implementation specifics around creating a polling driver use the - <constant>#ifdef CONFIG_CONSOLE_POLL</constant>, as shown above. - Keep in mind that polling hooks have to be implemented in such a way - that they can be called from an atomic context and have to restore - the state of the UART chip on return such that the system can return - to normal when the debugger detaches. You need to be very careful - with any kind of lock you consider, because failing here is most likely - going to mean pressing the reset button. - </para> - </sect2> - <sect2 id="kgdbocKbd"> - <title>kgdboc and keyboards</title> - <para>The kgdboc driver contains logic to configure communications - with an attached keyboard. The keyboard infrastructure is only - compiled into the kernel when CONFIG_KDB_KEYBOARD=y is set in the - kernel configuration.</para> - <para>The core polled keyboard driver driver for PS/2 type keyboards - is in drivers/char/kdb_keyboard.c. This driver is hooked into the - debug core when kgdboc populates the callback in the array - called <constant>kdb_poll_funcs[]</constant>. The - kdb_get_kbd_char() is the top-level function which polls hardware - for single character input. - </para> - </sect2> - <sect2 id="kgdbocKms"> - <title>kgdboc and kms</title> - <para>The kgdboc driver contains logic to request the graphics - display to switch to a text context when you are using - "kgdboc=kms,kbd", provided that you have a video driver which has a - frame buffer console and atomic kernel mode setting support.</para> - <para> - Every time the kernel - debugger is entered it calls kgdboc_pre_exp_handler() which in turn - calls con_debug_enter() in the virtual console layer. On resuming kernel - execution, the kernel debugger calls kgdboc_post_exp_handler() which - in turn calls con_debug_leave().</para> - <para>Any video driver that wants to be compatible with the kernel - debugger and the atomic kms callbacks must implement the - mode_set_base_atomic, fb_debug_enter and fb_debug_leave operations. - For the fb_debug_enter and fb_debug_leave the option exists to use - the generic drm fb helper functions or implement something custom for - the hardware. The following example shows the initialization of the - .mode_set_base_atomic operation in - drivers/gpu/drm/i915/intel_display.c: - <informalexample> - <programlisting> -static const struct drm_crtc_helper_funcs intel_helper_funcs = { -[...] - .mode_set_base_atomic = intel_pipe_set_base_atomic, -[...] -}; - </programlisting> - </informalexample> - </para> - <para>Here is an example of how the i915 driver initializes the fb_debug_enter and fb_debug_leave functions to use the generic drm helpers in - drivers/gpu/drm/i915/intel_fb.c: - <informalexample> - <programlisting> -static struct fb_ops intelfb_ops = { -[...] - .fb_debug_enter = drm_fb_helper_debug_enter, - .fb_debug_leave = drm_fb_helper_debug_leave, -[...] -}; - </programlisting> - </informalexample> - </para> - </sect2> - </sect1> - </chapter> - <chapter id="credits"> - <title>Credits</title> - <para> - The following people have contributed to this document: - <orderedlist> - <listitem><para>Amit Kale<email>amitkale@linsyssoft.com</email></para></listitem> - <listitem><para>Tom Rini<email>trini@kernel.crashing.org</email></para></listitem> - </orderedlist> - In March 2008 this document was completely rewritten by: - <itemizedlist> - <listitem><para>Jason Wessel<email>jason.wessel@windriver.com</email></para></listitem> - </itemizedlist> - In Jan 2010 this document was updated to include kdb. - <itemizedlist> - <listitem><para>Jason Wessel<email>jason.wessel@windriver.com</email></para></listitem> - </itemizedlist> - </para> - </chapter> -</book> - diff --git a/Documentation/DocBook/libata.tmpl b/Documentation/DocBook/libata.tmpl deleted file mode 100644 index 0320910b866d..000000000000 --- a/Documentation/DocBook/libata.tmpl +++ /dev/null @@ -1,1625 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="libataDevGuide"> - <bookinfo> - <title>libATA Developer's Guide</title> - - <authorgroup> - <author> - <firstname>Jeff</firstname> - <surname>Garzik</surname> - </author> - </authorgroup> - - <copyright> - <year>2003-2006</year> - <holder>Jeff Garzik</holder> - </copyright> - - <legalnotice> - <para> - The contents of this file are subject to the Open - Software License version 1.1 that can be found at - <ulink url="http://fedoraproject.org/wiki/Licensing:OSL1.1">http://fedoraproject.org/wiki/Licensing:OSL1.1</ulink> - and is included herein by reference. - </para> - - <para> - Alternatively, the contents of this file may be used under the terms - of the GNU General Public License version 2 (the "GPL") as distributed - in the kernel source COPYING file, in which case the provisions of - the GPL are applicable instead of the above. If you wish to allow - the use of your version of this file only under the terms of the - GPL and not to allow others to use your version of this file under - the OSL, indicate your decision by deleting the provisions above and - replace them with the notice and other provisions required by the GPL. - If you do not delete the provisions above, a recipient may use your - version of this file under either the OSL or the GPL. - </para> - - </legalnotice> - </bookinfo> - -<toc></toc> - - <chapter id="libataIntroduction"> - <title>Introduction</title> - <para> - libATA is a library used inside the Linux kernel to support ATA host - controllers and devices. libATA provides an ATA driver API, class - transports for ATA and ATAPI devices, and SCSI<->ATA translation - for ATA devices according to the T10 SAT specification. - </para> - <para> - This Guide documents the libATA driver API, library functions, library - internals, and a couple sample ATA low-level drivers. - </para> - </chapter> - - <chapter id="libataDriverApi"> - <title>libata Driver API</title> - <para> - struct ata_port_operations is defined for every low-level libata - hardware driver, and it controls how the low-level driver - interfaces with the ATA and SCSI layers. - </para> - <para> - FIS-based drivers will hook into the system with ->qc_prep() and - ->qc_issue() high-level hooks. Hardware which behaves in a manner - similar to PCI IDE hardware may utilize several generic helpers, - defining at a bare minimum the bus I/O addresses of the ATA shadow - register blocks. - </para> - <sect1> - <title>struct ata_port_operations</title> - - <sect2><title>Disable ATA port</title> - <programlisting> -void (*port_disable) (struct ata_port *); - </programlisting> - - <para> - Called from ata_bus_probe() error path, as well as when - unregistering from the SCSI module (rmmod, hot unplug). - This function should do whatever needs to be done to take the - port out of use. In most cases, ata_port_disable() can be used - as this hook. - </para> - <para> - Called from ata_bus_probe() on a failed probe. - Called from ata_scsi_release(). - </para> - - </sect2> - - <sect2><title>Post-IDENTIFY device configuration</title> - <programlisting> -void (*dev_config) (struct ata_port *, struct ata_device *); - </programlisting> - - <para> - Called after IDENTIFY [PACKET] DEVICE is issued to each device - found. Typically used to apply device-specific fixups prior to - issue of SET FEATURES - XFER MODE, and prior to operation. - </para> - <para> - This entry may be specified as NULL in ata_port_operations. - </para> - - </sect2> - - <sect2><title>Set PIO/DMA mode</title> - <programlisting> -void (*set_piomode) (struct ata_port *, struct ata_device *); -void (*set_dmamode) (struct ata_port *, struct ata_device *); -void (*post_set_mode) (struct ata_port *); -unsigned int (*mode_filter) (struct ata_port *, struct ata_device *, unsigned int); - </programlisting> - - <para> - Hooks called prior to the issue of SET FEATURES - XFER MODE - command. The optional ->mode_filter() hook is called when libata - has built a mask of the possible modes. This is passed to the - ->mode_filter() function which should return a mask of valid modes - after filtering those unsuitable due to hardware limits. It is not - valid to use this interface to add modes. - </para> - <para> - dev->pio_mode and dev->dma_mode are guaranteed to be valid when - ->set_piomode() and when ->set_dmamode() is called. The timings for - any other drive sharing the cable will also be valid at this point. - That is the library records the decisions for the modes of each - drive on a channel before it attempts to set any of them. - </para> - <para> - ->post_set_mode() is - called unconditionally, after the SET FEATURES - XFER MODE - command completes successfully. - </para> - - <para> - ->set_piomode() is always called (if present), but - ->set_dma_mode() is only called if DMA is possible. - </para> - - </sect2> - - <sect2><title>Taskfile read/write</title> - <programlisting> -void (*sff_tf_load) (struct ata_port *ap, struct ata_taskfile *tf); -void (*sff_tf_read) (struct ata_port *ap, struct ata_taskfile *tf); - </programlisting> - - <para> - ->tf_load() is called to load the given taskfile into hardware - registers / DMA buffers. ->tf_read() is called to read the - hardware registers / DMA buffers, to obtain the current set of - taskfile register values. - Most drivers for taskfile-based hardware (PIO or MMIO) use - ata_sff_tf_load() and ata_sff_tf_read() for these hooks. - </para> - - </sect2> - - <sect2><title>PIO data read/write</title> - <programlisting> -void (*sff_data_xfer) (struct ata_device *, unsigned char *, unsigned int, int); - </programlisting> - - <para> -All bmdma-style drivers must implement this hook. This is the low-level -operation that actually copies the data bytes during a PIO data -transfer. -Typically the driver will choose one of ata_sff_data_xfer_noirq(), -ata_sff_data_xfer(), or ata_sff_data_xfer32(). - </para> - - </sect2> - - <sect2><title>ATA command execute</title> - <programlisting> -void (*sff_exec_command)(struct ata_port *ap, struct ata_taskfile *tf); - </programlisting> - - <para> - causes an ATA command, previously loaded with - ->tf_load(), to be initiated in hardware. - Most drivers for taskfile-based hardware use ata_sff_exec_command() - for this hook. - </para> - - </sect2> - - <sect2><title>Per-cmd ATAPI DMA capabilities filter</title> - <programlisting> -int (*check_atapi_dma) (struct ata_queued_cmd *qc); - </programlisting> - - <para> -Allow low-level driver to filter ATA PACKET commands, returning a status -indicating whether or not it is OK to use DMA for the supplied PACKET -command. - </para> - <para> - This hook may be specified as NULL, in which case libata will - assume that atapi dma can be supported. - </para> - - </sect2> - - <sect2><title>Read specific ATA shadow registers</title> - <programlisting> -u8 (*sff_check_status)(struct ata_port *ap); -u8 (*sff_check_altstatus)(struct ata_port *ap); - </programlisting> - - <para> - Reads the Status/AltStatus ATA shadow register from - hardware. On some hardware, reading the Status register has - the side effect of clearing the interrupt condition. - Most drivers for taskfile-based hardware use - ata_sff_check_status() for this hook. - </para> - - </sect2> - - <sect2><title>Write specific ATA shadow register</title> - <programlisting> -void (*sff_set_devctl)(struct ata_port *ap, u8 ctl); - </programlisting> - - <para> - Write the device control ATA shadow register to the hardware. - Most drivers don't need to define this. - </para> - - </sect2> - - <sect2><title>Select ATA device on bus</title> - <programlisting> -void (*sff_dev_select)(struct ata_port *ap, unsigned int device); - </programlisting> - - <para> - Issues the low-level hardware command(s) that causes one of N - hardware devices to be considered 'selected' (active and - available for use) on the ATA bus. This generally has no - meaning on FIS-based devices. - </para> - <para> - Most drivers for taskfile-based hardware use - ata_sff_dev_select() for this hook. - </para> - - </sect2> - - <sect2><title>Private tuning method</title> - <programlisting> -void (*set_mode) (struct ata_port *ap); - </programlisting> - - <para> - By default libata performs drive and controller tuning in - accordance with the ATA timing rules and also applies blacklists - and cable limits. Some controllers need special handling and have - custom tuning rules, typically raid controllers that use ATA - commands but do not actually do drive timing. - </para> - - <warning> - <para> - This hook should not be used to replace the standard controller - tuning logic when a controller has quirks. Replacing the default - tuning logic in that case would bypass handling for drive and - bridge quirks that may be important to data reliability. If a - controller needs to filter the mode selection it should use the - mode_filter hook instead. - </para> - </warning> - - </sect2> - - <sect2><title>Control PCI IDE BMDMA engine</title> - <programlisting> -void (*bmdma_setup) (struct ata_queued_cmd *qc); -void (*bmdma_start) (struct ata_queued_cmd *qc); -void (*bmdma_stop) (struct ata_port *ap); -u8 (*bmdma_status) (struct ata_port *ap); - </programlisting> - - <para> -When setting up an IDE BMDMA transaction, these hooks arm -(->bmdma_setup), fire (->bmdma_start), and halt (->bmdma_stop) -the hardware's DMA engine. ->bmdma_status is used to read the standard -PCI IDE DMA Status register. - </para> - - <para> -These hooks are typically either no-ops, or simply not implemented, in -FIS-based drivers. - </para> - <para> -Most legacy IDE drivers use ata_bmdma_setup() for the bmdma_setup() -hook. ata_bmdma_setup() will write the pointer to the PRD table to -the IDE PRD Table Address register, enable DMA in the DMA Command -register, and call exec_command() to begin the transfer. - </para> - <para> -Most legacy IDE drivers use ata_bmdma_start() for the bmdma_start() -hook. ata_bmdma_start() will write the ATA_DMA_START flag to the DMA -Command register. - </para> - <para> -Many legacy IDE drivers use ata_bmdma_stop() for the bmdma_stop() -hook. ata_bmdma_stop() clears the ATA_DMA_START flag in the DMA -command register. - </para> - <para> -Many legacy IDE drivers use ata_bmdma_status() as the bmdma_status() hook. - </para> - - </sect2> - - <sect2><title>High-level taskfile hooks</title> - <programlisting> -void (*qc_prep) (struct ata_queued_cmd *qc); -int (*qc_issue) (struct ata_queued_cmd *qc); - </programlisting> - - <para> - Higher-level hooks, these two hooks can potentially supercede - several of the above taskfile/DMA engine hooks. ->qc_prep is - called after the buffers have been DMA-mapped, and is typically - used to populate the hardware's DMA scatter-gather table. - Most drivers use the standard ata_qc_prep() helper function, but - more advanced drivers roll their own. - </para> - <para> - ->qc_issue is used to make a command active, once the hardware - and S/G tables have been prepared. IDE BMDMA drivers use the - helper function ata_qc_issue_prot() for taskfile protocol-based - dispatch. More advanced drivers implement their own ->qc_issue. - </para> - <para> - ata_qc_issue_prot() calls ->tf_load(), ->bmdma_setup(), and - ->bmdma_start() as necessary to initiate a transfer. - </para> - - </sect2> - - <sect2><title>Exception and probe handling (EH)</title> - <programlisting> -void (*eng_timeout) (struct ata_port *ap); -void (*phy_reset) (struct ata_port *ap); - </programlisting> - - <para> -Deprecated. Use ->error_handler() instead. - </para> - - <programlisting> -void (*freeze) (struct ata_port *ap); -void (*thaw) (struct ata_port *ap); - </programlisting> - - <para> -ata_port_freeze() is called when HSM violations or some other -condition disrupts normal operation of the port. A frozen port -is not allowed to perform any operation until the port is -thawed, which usually follows a successful reset. - </para> - - <para> -The optional ->freeze() callback can be used for freezing the port -hardware-wise (e.g. mask interrupt and stop DMA engine). If a -port cannot be frozen hardware-wise, the interrupt handler -must ack and clear interrupts unconditionally while the port -is frozen. - </para> - <para> -The optional ->thaw() callback is called to perform the opposite of ->freeze(): -prepare the port for normal operation once again. Unmask interrupts, -start DMA engine, etc. - </para> - - <programlisting> -void (*error_handler) (struct ata_port *ap); - </programlisting> - - <para> -->error_handler() is a driver's hook into probe, hotplug, and recovery -and other exceptional conditions. The primary responsibility of an -implementation is to call ata_do_eh() or ata_bmdma_drive_eh() with a set -of EH hooks as arguments: - </para> - - <para> -'prereset' hook (may be NULL) is called during an EH reset, before any other actions -are taken. - </para> - - <para> -'postreset' hook (may be NULL) is called after the EH reset is performed. Based on -existing conditions, severity of the problem, and hardware capabilities, - </para> - - <para> -Either 'softreset' (may be NULL) or 'hardreset' (may be NULL) will be -called to perform the low-level EH reset. - </para> - - <programlisting> -void (*post_internal_cmd) (struct ata_queued_cmd *qc); - </programlisting> - - <para> -Perform any hardware-specific actions necessary to finish processing -after executing a probe-time or EH-time command via ata_exec_internal(). - </para> - - </sect2> - - <sect2><title>Hardware interrupt handling</title> - <programlisting> -irqreturn_t (*irq_handler)(int, void *, struct pt_regs *); -void (*irq_clear) (struct ata_port *); - </programlisting> - - <para> - ->irq_handler is the interrupt handling routine registered with - the system, by libata. ->irq_clear is called during probe just - before the interrupt handler is registered, to be sure hardware - is quiet. - </para> - <para> - The second argument, dev_instance, should be cast to a pointer - to struct ata_host_set. - </para> - <para> - Most legacy IDE drivers use ata_sff_interrupt() for the - irq_handler hook, which scans all ports in the host_set, - determines which queued command was active (if any), and calls - ata_sff_host_intr(ap,qc). - </para> - <para> - Most legacy IDE drivers use ata_sff_irq_clear() for the - irq_clear() hook, which simply clears the interrupt and error - flags in the DMA status register. - </para> - - </sect2> - - <sect2><title>SATA phy read/write</title> - <programlisting> -int (*scr_read) (struct ata_port *ap, unsigned int sc_reg, - u32 *val); -int (*scr_write) (struct ata_port *ap, unsigned int sc_reg, - u32 val); - </programlisting> - - <para> - Read and write standard SATA phy registers. Currently only used - if ->phy_reset hook called the sata_phy_reset() helper function. - sc_reg is one of SCR_STATUS, SCR_CONTROL, SCR_ERROR, or SCR_ACTIVE. - </para> - - </sect2> - - <sect2><title>Init and shutdown</title> - <programlisting> -int (*port_start) (struct ata_port *ap); -void (*port_stop) (struct ata_port *ap); -void (*host_stop) (struct ata_host_set *host_set); - </programlisting> - - <para> - ->port_start() is called just after the data structures for each - port are initialized. Typically this is used to alloc per-port - DMA buffers / tables / rings, enable DMA engines, and similar - tasks. Some drivers also use this entry point as a chance to - allocate driver-private memory for ap->private_data. - </para> - <para> - Many drivers use ata_port_start() as this hook or call - it from their own port_start() hooks. ata_port_start() - allocates space for a legacy IDE PRD table and returns. - </para> - <para> - ->port_stop() is called after ->host_stop(). Its sole function - is to release DMA/memory resources, now that they are no longer - actively being used. Many drivers also free driver-private - data from port at this time. - </para> - <para> - ->host_stop() is called after all ->port_stop() calls -have completed. The hook must finalize hardware shutdown, release DMA -and other resources, etc. - This hook may be specified as NULL, in which case it is not called. - </para> - - </sect2> - - </sect1> - </chapter> - - <chapter id="libataEH"> - <title>Error handling</title> - - <para> - This chapter describes how errors are handled under libata. - Readers are advised to read SCSI EH - (Documentation/scsi/scsi_eh.txt) and ATA exceptions doc first. - </para> - - <sect1><title>Origins of commands</title> - <para> - In libata, a command is represented with struct ata_queued_cmd - or qc. qc's are preallocated during port initialization and - repetitively used for command executions. Currently only one - qc is allocated per port but yet-to-be-merged NCQ branch - allocates one for each tag and maps each qc to NCQ tag 1-to-1. - </para> - <para> - libata commands can originate from two sources - libata itself - and SCSI midlayer. libata internal commands are used for - initialization and error handling. All normal blk requests - and commands for SCSI emulation are passed as SCSI commands - through queuecommand callback of SCSI host template. - </para> - </sect1> - - <sect1><title>How commands are issued</title> - - <variablelist> - - <varlistentry><term>Internal commands</term> - <listitem> - <para> - First, qc is allocated and initialized using - ata_qc_new_init(). Although ata_qc_new_init() doesn't - implement any wait or retry mechanism when qc is not - available, internal commands are currently issued only during - initialization and error recovery, so no other command is - active and allocation is guaranteed to succeed. - </para> - <para> - Once allocated qc's taskfile is initialized for the command to - be executed. qc currently has two mechanisms to notify - completion. One is via qc->complete_fn() callback and the - other is completion qc->waiting. qc->complete_fn() callback - is the asynchronous path used by normal SCSI translated - commands and qc->waiting is the synchronous (issuer sleeps in - process context) path used by internal commands. - </para> - <para> - Once initialization is complete, host_set lock is acquired - and the qc is issued. - </para> - </listitem> - </varlistentry> - - <varlistentry><term>SCSI commands</term> - <listitem> - <para> - All libata drivers use ata_scsi_queuecmd() as - hostt->queuecommand callback. scmds can either be simulated - or translated. No qc is involved in processing a simulated - scmd. The result is computed right away and the scmd is - completed. - </para> - <para> - For a translated scmd, ata_qc_new_init() is invoked to - allocate a qc and the scmd is translated into the qc. SCSI - midlayer's completion notification function pointer is stored - into qc->scsidone. - </para> - <para> - qc->complete_fn() callback is used for completion - notification. ATA commands use ata_scsi_qc_complete() while - ATAPI commands use atapi_qc_complete(). Both functions end up - calling qc->scsidone to notify upper layer when the qc is - finished. After translation is completed, the qc is issued - with ata_qc_issue(). - </para> - <para> - Note that SCSI midlayer invokes hostt->queuecommand while - holding host_set lock, so all above occur while holding - host_set lock. - </para> - </listitem> - </varlistentry> - - </variablelist> - </sect1> - - <sect1><title>How commands are processed</title> - <para> - Depending on which protocol and which controller are used, - commands are processed differently. For the purpose of - discussion, a controller which uses taskfile interface and all - standard callbacks is assumed. - </para> - <para> - Currently 6 ATA command protocols are used. They can be - sorted into the following four categories according to how - they are processed. - </para> - - <variablelist> - <varlistentry><term>ATA NO DATA or DMA</term> - <listitem> - <para> - ATA_PROT_NODATA and ATA_PROT_DMA fall into this category. - These types of commands don't require any software - intervention once issued. Device will raise interrupt on - completion. - </para> - </listitem> - </varlistentry> - - <varlistentry><term>ATA PIO</term> - <listitem> - <para> - ATA_PROT_PIO is in this category. libata currently - implements PIO with polling. ATA_NIEN bit is set to turn - off interrupt and pio_task on ata_wq performs polling and - IO. - </para> - </listitem> - </varlistentry> - - <varlistentry><term>ATAPI NODATA or DMA</term> - <listitem> - <para> - ATA_PROT_ATAPI_NODATA and ATA_PROT_ATAPI_DMA are in this - category. packet_task is used to poll BSY bit after - issuing PACKET command. Once BSY is turned off by the - device, packet_task transfers CDB and hands off processing - to interrupt handler. - </para> - </listitem> - </varlistentry> - - <varlistentry><term>ATAPI PIO</term> - <listitem> - <para> - ATA_PROT_ATAPI is in this category. ATA_NIEN bit is set - and, as in ATAPI NODATA or DMA, packet_task submits cdb. - However, after submitting cdb, further processing (data - transfer) is handed off to pio_task. - </para> - </listitem> - </varlistentry> - </variablelist> - </sect1> - - <sect1><title>How commands are completed</title> - <para> - Once issued, all qc's are either completed with - ata_qc_complete() or time out. For commands which are handled - by interrupts, ata_host_intr() invokes ata_qc_complete(), and, - for PIO tasks, pio_task invokes ata_qc_complete(). In error - cases, packet_task may also complete commands. - </para> - <para> - ata_qc_complete() does the following. - </para> - - <orderedlist> - - <listitem> - <para> - DMA memory is unmapped. - </para> - </listitem> - - <listitem> - <para> - ATA_QCFLAG_ACTIVE is cleared from qc->flags. - </para> - </listitem> - - <listitem> - <para> - qc->complete_fn() callback is invoked. If the return value of - the callback is not zero. Completion is short circuited and - ata_qc_complete() returns. - </para> - </listitem> - - <listitem> - <para> - __ata_qc_complete() is called, which does - <orderedlist> - - <listitem> - <para> - qc->flags is cleared to zero. - </para> - </listitem> - - <listitem> - <para> - ap->active_tag and qc->tag are poisoned. - </para> - </listitem> - - <listitem> - <para> - qc->waiting is cleared & completed (in that order). - </para> - </listitem> - - <listitem> - <para> - qc is deallocated by clearing appropriate bit in ap->qactive. - </para> - </listitem> - - </orderedlist> - </para> - </listitem> - - </orderedlist> - - <para> - So, it basically notifies upper layer and deallocates qc. One - exception is short-circuit path in #3 which is used by - atapi_qc_complete(). - </para> - <para> - For all non-ATAPI commands, whether it fails or not, almost - the same code path is taken and very little error handling - takes place. A qc is completed with success status if it - succeeded, with failed status otherwise. - </para> - <para> - However, failed ATAPI commands require more handling as - REQUEST SENSE is needed to acquire sense data. If an ATAPI - command fails, ata_qc_complete() is invoked with error status, - which in turn invokes atapi_qc_complete() via - qc->complete_fn() callback. - </para> - <para> - This makes atapi_qc_complete() set scmd->result to - SAM_STAT_CHECK_CONDITION, complete the scmd and return 1. As - the sense data is empty but scmd->result is CHECK CONDITION, - SCSI midlayer will invoke EH for the scmd, and returning 1 - makes ata_qc_complete() to return without deallocating the qc. - This leads us to ata_scsi_error() with partially completed qc. - </para> - - </sect1> - - <sect1><title>ata_scsi_error()</title> - <para> - ata_scsi_error() is the current transportt->eh_strategy_handler() - for libata. As discussed above, this will be entered in two - cases - timeout and ATAPI error completion. This function - calls low level libata driver's eng_timeout() callback, the - standard callback for which is ata_eng_timeout(). It checks - if a qc is active and calls ata_qc_timeout() on the qc if so. - Actual error handling occurs in ata_qc_timeout(). - </para> - <para> - If EH is invoked for timeout, ata_qc_timeout() stops BMDMA and - completes the qc. Note that as we're currently in EH, we - cannot call scsi_done. As described in SCSI EH doc, a - recovered scmd should be either retried with - scsi_queue_insert() or finished with scsi_finish_command(). - Here, we override qc->scsidone with scsi_finish_command() and - calls ata_qc_complete(). - </para> - <para> - If EH is invoked due to a failed ATAPI qc, the qc here is - completed but not deallocated. The purpose of this - half-completion is to use the qc as place holder to make EH - code reach this place. This is a bit hackish, but it works. - </para> - <para> - Once control reaches here, the qc is deallocated by invoking - __ata_qc_complete() explicitly. Then, internal qc for REQUEST - SENSE is issued. Once sense data is acquired, scmd is - finished by directly invoking scsi_finish_command() on the - scmd. Note that as we already have completed and deallocated - the qc which was associated with the scmd, we don't need - to/cannot call ata_qc_complete() again. - </para> - - </sect1> - - <sect1><title>Problems with the current EH</title> - - <itemizedlist> - - <listitem> - <para> - Error representation is too crude. Currently any and all - error conditions are represented with ATA STATUS and ERROR - registers. Errors which aren't ATA device errors are treated - as ATA device errors by setting ATA_ERR bit. Better error - descriptor which can properly represent ATA and other - errors/exceptions is needed. - </para> - </listitem> - - <listitem> - <para> - When handling timeouts, no action is taken to make device - forget about the timed out command and ready for new commands. - </para> - </listitem> - - <listitem> - <para> - EH handling via ata_scsi_error() is not properly protected - from usual command processing. On EH entrance, the device is - not in quiescent state. Timed out commands may succeed or - fail any time. pio_task and atapi_task may still be running. - </para> - </listitem> - - <listitem> - <para> - Too weak error recovery. Devices / controllers causing HSM - mismatch errors and other errors quite often require reset to - return to known state. Also, advanced error handling is - necessary to support features like NCQ and hotplug. - </para> - </listitem> - - <listitem> - <para> - ATA errors are directly handled in the interrupt handler and - PIO errors in pio_task. This is problematic for advanced - error handling for the following reasons. - </para> - <para> - First, advanced error handling often requires context and - internal qc execution. - </para> - <para> - Second, even a simple failure (say, CRC error) needs - information gathering and could trigger complex error handling - (say, resetting & reconfiguring). Having multiple code - paths to gather information, enter EH and trigger actions - makes life painful. - </para> - <para> - Third, scattered EH code makes implementing low level drivers - difficult. Low level drivers override libata callbacks. If - EH is scattered over several places, each affected callbacks - should perform its part of error handling. This can be error - prone and painful. - </para> - </listitem> - - </itemizedlist> - </sect1> - </chapter> - - <chapter id="libataExt"> - <title>libata Library</title> -!Edrivers/ata/libata-core.c - </chapter> - - <chapter id="libataInt"> - <title>libata Core Internals</title> -!Idrivers/ata/libata-core.c - </chapter> - - <chapter id="libataScsiInt"> - <title>libata SCSI translation/emulation</title> -!Edrivers/ata/libata-scsi.c -!Idrivers/ata/libata-scsi.c - </chapter> - - <chapter id="ataExceptions"> - <title>ATA errors and exceptions</title> - - <para> - This chapter tries to identify what error/exception conditions exist - for ATA/ATAPI devices and describe how they should be handled in - implementation-neutral way. - </para> - - <para> - The term 'error' is used to describe conditions where either an - explicit error condition is reported from device or a command has - timed out. - </para> - - <para> - The term 'exception' is either used to describe exceptional - conditions which are not errors (say, power or hotplug events), or - to describe both errors and non-error exceptional conditions. Where - explicit distinction between error and exception is necessary, the - term 'non-error exception' is used. - </para> - - <sect1 id="excat"> - <title>Exception categories</title> - <para> - Exceptions are described primarily with respect to legacy - taskfile + bus master IDE interface. If a controller provides - other better mechanism for error reporting, mapping those into - categories described below shouldn't be difficult. - </para> - - <para> - In the following sections, two recovery actions - reset and - reconfiguring transport - are mentioned. These are described - further in <xref linkend="exrec"/>. - </para> - - <sect2 id="excatHSMviolation"> - <title>HSM violation</title> - <para> - This error is indicated when STATUS value doesn't match HSM - requirement during issuing or execution any ATA/ATAPI command. - </para> - - <itemizedlist> - <title>Examples</title> - - <listitem> - <para> - ATA_STATUS doesn't contain !BSY && DRDY && !DRQ while trying - to issue a command. - </para> - </listitem> - - <listitem> - <para> - !BSY && !DRQ during PIO data transfer. - </para> - </listitem> - - <listitem> - <para> - DRQ on command completion. - </para> - </listitem> - - <listitem> - <para> - !BSY && ERR after CDB transfer starts but before the - last byte of CDB is transferred. ATA/ATAPI standard states - that "The device shall not terminate the PACKET command - with an error before the last byte of the command packet has - been written" in the error outputs description of PACKET - command and the state diagram doesn't include such - transitions. - </para> - </listitem> - - </itemizedlist> - - <para> - In these cases, HSM is violated and not much information - regarding the error can be acquired from STATUS or ERROR - register. IOW, this error can be anything - driver bug, - faulty device, controller and/or cable. - </para> - - <para> - As HSM is violated, reset is necessary to restore known state. - Reconfiguring transport for lower speed might be helpful too - as transmission errors sometimes cause this kind of errors. - </para> - </sect2> - - <sect2 id="excatDevErr"> - <title>ATA/ATAPI device error (non-NCQ / non-CHECK CONDITION)</title> - - <para> - These are errors detected and reported by ATA/ATAPI devices - indicating device problems. For this type of errors, STATUS - and ERROR register values are valid and describe error - condition. Note that some of ATA bus errors are detected by - ATA/ATAPI devices and reported using the same mechanism as - device errors. Those cases are described later in this - section. - </para> - - <para> - For ATA commands, this type of errors are indicated by !BSY - && ERR during command execution and on completion. - </para> - - <para>For ATAPI commands,</para> - - <itemizedlist> - - <listitem> - <para> - !BSY && ERR && ABRT right after issuing PACKET - indicates that PACKET command is not supported and falls in - this category. - </para> - </listitem> - - <listitem> - <para> - !BSY && ERR(==CHK) && !ABRT after the last - byte of CDB is transferred indicates CHECK CONDITION and - doesn't fall in this category. - </para> - </listitem> - - <listitem> - <para> - !BSY && ERR(==CHK) && ABRT after the last byte - of CDB is transferred *probably* indicates CHECK CONDITION and - doesn't fall in this category. - </para> - </listitem> - - </itemizedlist> - - <para> - Of errors detected as above, the following are not ATA/ATAPI - device errors but ATA bus errors and should be handled - according to <xref linkend="excatATAbusErr"/>. - </para> - - <variablelist> - - <varlistentry> - <term>CRC error during data transfer</term> - <listitem> - <para> - This is indicated by ICRC bit in the ERROR register and - means that corruption occurred during data transfer. Up to - ATA/ATAPI-7, the standard specifies that this bit is only - applicable to UDMA transfers but ATA/ATAPI-8 draft revision - 1f says that the bit may be applicable to multiword DMA and - PIO. - </para> - </listitem> - </varlistentry> - - <varlistentry> - <term>ABRT error during data transfer or on completion</term> - <listitem> - <para> - Up to ATA/ATAPI-7, the standard specifies that ABRT could be - set on ICRC errors and on cases where a device is not able - to complete a command. Combined with the fact that MWDMA - and PIO transfer errors aren't allowed to use ICRC bit up to - ATA/ATAPI-7, it seems to imply that ABRT bit alone could - indicate transfer errors. - </para> - <para> - However, ATA/ATAPI-8 draft revision 1f removes the part - that ICRC errors can turn on ABRT. So, this is kind of - gray area. Some heuristics are needed here. - </para> - </listitem> - </varlistentry> - - </variablelist> - - <para> - ATA/ATAPI device errors can be further categorized as follows. - </para> - - <variablelist> - - <varlistentry> - <term>Media errors</term> - <listitem> - <para> - This is indicated by UNC bit in the ERROR register. ATA - devices reports UNC error only after certain number of - retries cannot recover the data, so there's nothing much - else to do other than notifying upper layer. - </para> - <para> - READ and WRITE commands report CHS or LBA of the first - failed sector but ATA/ATAPI standard specifies that the - amount of transferred data on error completion is - indeterminate, so we cannot assume that sectors preceding - the failed sector have been transferred and thus cannot - complete those sectors successfully as SCSI does. - </para> - </listitem> - </varlistentry> - - <varlistentry> - <term>Media changed / media change requested error</term> - <listitem> - <para> - <<TODO: fill here>> - </para> - </listitem> - </varlistentry> - - <varlistentry><term>Address error</term> - <listitem> - <para> - This is indicated by IDNF bit in the ERROR register. - Report to upper layer. - </para> - </listitem> - </varlistentry> - - <varlistentry><term>Other errors</term> - <listitem> - <para> - This can be invalid command or parameter indicated by ABRT - ERROR bit or some other error condition. Note that ABRT - bit can indicate a lot of things including ICRC and Address - errors. Heuristics needed. - </para> - </listitem> - </varlistentry> - - </variablelist> - - <para> - Depending on commands, not all STATUS/ERROR bits are - applicable. These non-applicable bits are marked with - "na" in the output descriptions but up to ATA/ATAPI-7 - no definition of "na" can be found. However, - ATA/ATAPI-8 draft revision 1f describes "N/A" as - follows. - </para> - - <blockquote> - <variablelist> - <varlistentry><term>3.2.3.3a N/A</term> - <listitem> - <para> - A keyword the indicates a field has no defined value in - this standard and should not be checked by the host or - device. N/A fields should be cleared to zero. - </para> - </listitem> - </varlistentry> - </variablelist> - </blockquote> - - <para> - So, it seems reasonable to assume that "na" bits are - cleared to zero by devices and thus need no explicit masking. - </para> - - </sect2> - - <sect2 id="excatATAPIcc"> - <title>ATAPI device CHECK CONDITION</title> - - <para> - ATAPI device CHECK CONDITION error is indicated by set CHK bit - (ERR bit) in the STATUS register after the last byte of CDB is - transferred for a PACKET command. For this kind of errors, - sense data should be acquired to gather information regarding - the errors. REQUEST SENSE packet command should be used to - acquire sense data. - </para> - - <para> - Once sense data is acquired, this type of errors can be - handled similarly to other SCSI errors. Note that sense data - may indicate ATA bus error (e.g. Sense Key 04h HARDWARE ERROR - && ASC/ASCQ 47h/00h SCSI PARITY ERROR). In such - cases, the error should be considered as an ATA bus error and - handled according to <xref linkend="excatATAbusErr"/>. - </para> - - </sect2> - - <sect2 id="excatNCQerr"> - <title>ATA device error (NCQ)</title> - - <para> - NCQ command error is indicated by cleared BSY and set ERR bit - during NCQ command phase (one or more NCQ commands - outstanding). Although STATUS and ERROR registers will - contain valid values describing the error, READ LOG EXT is - required to clear the error condition, determine which command - has failed and acquire more information. - </para> - - <para> - READ LOG EXT Log Page 10h reports which tag has failed and - taskfile register values describing the error. With this - information the failed command can be handled as a normal ATA - command error as in <xref linkend="excatDevErr"/> and all - other in-flight commands must be retried. Note that this - retry should not be counted - it's likely that commands - retried this way would have completed normally if it were not - for the failed command. - </para> - - <para> - Note that ATA bus errors can be reported as ATA device NCQ - errors. This should be handled as described in <xref - linkend="excatATAbusErr"/>. - </para> - - <para> - If READ LOG EXT Log Page 10h fails or reports NQ, we're - thoroughly screwed. This condition should be treated - according to <xref linkend="excatHSMviolation"/>. - </para> - - </sect2> - - <sect2 id="excatATAbusErr"> - <title>ATA bus error</title> - - <para> - ATA bus error means that data corruption occurred during - transmission over ATA bus (SATA or PATA). This type of errors - can be indicated by - </para> - - <itemizedlist> - - <listitem> - <para> - ICRC or ABRT error as described in <xref linkend="excatDevErr"/>. - </para> - </listitem> - - <listitem> - <para> - Controller-specific error completion with error information - indicating transmission error. - </para> - </listitem> - - <listitem> - <para> - On some controllers, command timeout. In this case, there may - be a mechanism to determine that the timeout is due to - transmission error. - </para> - </listitem> - - <listitem> - <para> - Unknown/random errors, timeouts and all sorts of weirdities. - </para> - </listitem> - - </itemizedlist> - - <para> - As described above, transmission errors can cause wide variety - of symptoms ranging from device ICRC error to random device - lockup, and, for many cases, there is no way to tell if an - error condition is due to transmission error or not; - therefore, it's necessary to employ some kind of heuristic - when dealing with errors and timeouts. For example, - encountering repetitive ABRT errors for known supported - command is likely to indicate ATA bus error. - </para> - - <para> - Once it's determined that ATA bus errors have possibly - occurred, lowering ATA bus transmission speed is one of - actions which may alleviate the problem. See <xref - linkend="exrecReconf"/> for more information. - </para> - - </sect2> - - <sect2 id="excatPCIbusErr"> - <title>PCI bus error</title> - - <para> - Data corruption or other failures during transmission over PCI - (or other system bus). For standard BMDMA, this is indicated - by Error bit in the BMDMA Status register. This type of - errors must be logged as it indicates something is very wrong - with the system. Resetting host controller is recommended. - </para> - - </sect2> - - <sect2 id="excatLateCompletion"> - <title>Late completion</title> - - <para> - This occurs when timeout occurs and the timeout handler finds - out that the timed out command has completed successfully or - with error. This is usually caused by lost interrupts. This - type of errors must be logged. Resetting host controller is - recommended. - </para> - - </sect2> - - <sect2 id="excatUnknown"> - <title>Unknown error (timeout)</title> - - <para> - This is when timeout occurs and the command is still - processing or the host and device are in unknown state. When - this occurs, HSM could be in any valid or invalid state. To - bring the device to known state and make it forget about the - timed out command, resetting is necessary. The timed out - command may be retried. - </para> - - <para> - Timeouts can also be caused by transmission errors. Refer to - <xref linkend="excatATAbusErr"/> for more details. - </para> - - </sect2> - - <sect2 id="excatHoplugPM"> - <title>Hotplug and power management exceptions</title> - - <para> - <<TODO: fill here>> - </para> - - </sect2> - - </sect1> - - <sect1 id="exrec"> - <title>EH recovery actions</title> - - <para> - This section discusses several important recovery actions. - </para> - - <sect2 id="exrecClr"> - <title>Clearing error condition</title> - - <para> - Many controllers require its error registers to be cleared by - error handler. Different controllers may have different - requirements. - </para> - - <para> - For SATA, it's strongly recommended to clear at least SError - register during error handling. - </para> - </sect2> - - <sect2 id="exrecRst"> - <title>Reset</title> - - <para> - During EH, resetting is necessary in the following cases. - </para> - - <itemizedlist> - - <listitem> - <para> - HSM is in unknown or invalid state - </para> - </listitem> - - <listitem> - <para> - HBA is in unknown or invalid state - </para> - </listitem> - - <listitem> - <para> - EH needs to make HBA/device forget about in-flight commands - </para> - </listitem> - - <listitem> - <para> - HBA/device behaves weirdly - </para> - </listitem> - - </itemizedlist> - - <para> - Resetting during EH might be a good idea regardless of error - condition to improve EH robustness. Whether to reset both or - either one of HBA and device depends on situation but the - following scheme is recommended. - </para> - - <itemizedlist> - - <listitem> - <para> - When it's known that HBA is in ready state but ATA/ATAPI - device is in unknown state, reset only device. - </para> - </listitem> - - <listitem> - <para> - If HBA is in unknown state, reset both HBA and device. - </para> - </listitem> - - </itemizedlist> - - <para> - HBA resetting is implementation specific. For a controller - complying to taskfile/BMDMA PCI IDE, stopping active DMA - transaction may be sufficient iff BMDMA state is the only HBA - context. But even mostly taskfile/BMDMA PCI IDE complying - controllers may have implementation specific requirements and - mechanism to reset themselves. This must be addressed by - specific drivers. - </para> - - <para> - OTOH, ATA/ATAPI standard describes in detail ways to reset - ATA/ATAPI devices. - </para> - - <variablelist> - - <varlistentry><term>PATA hardware reset</term> - <listitem> - <para> - This is hardware initiated device reset signalled with - asserted PATA RESET- signal. There is no standard way to - initiate hardware reset from software although some - hardware provides registers that allow driver to directly - tweak the RESET- signal. - </para> - </listitem> - </varlistentry> - - <varlistentry><term>Software reset</term> - <listitem> - <para> - This is achieved by turning CONTROL SRST bit on for at - least 5us. Both PATA and SATA support it but, in case of - SATA, this may require controller-specific support as the - second Register FIS to clear SRST should be transmitted - while BSY bit is still set. Note that on PATA, this resets - both master and slave devices on a channel. - </para> - </listitem> - </varlistentry> - - <varlistentry><term>EXECUTE DEVICE DIAGNOSTIC command</term> - <listitem> - <para> - Although ATA/ATAPI standard doesn't describe exactly, EDD - implies some level of resetting, possibly similar level - with software reset. Host-side EDD protocol can be handled - with normal command processing and most SATA controllers - should be able to handle EDD's just like other commands. - As in software reset, EDD affects both devices on a PATA - bus. - </para> - <para> - Although EDD does reset devices, this doesn't suit error - handling as EDD cannot be issued while BSY is set and it's - unclear how it will act when device is in unknown/weird - state. - </para> - </listitem> - </varlistentry> - - <varlistentry><term>ATAPI DEVICE RESET command</term> - <listitem> - <para> - This is very similar to software reset except that reset - can be restricted to the selected device without affecting - the other device sharing the cable. - </para> - </listitem> - </varlistentry> - - <varlistentry><term>SATA phy reset</term> - <listitem> - <para> - This is the preferred way of resetting a SATA device. In - effect, it's identical to PATA hardware reset. Note that - this can be done with the standard SCR Control register. - As such, it's usually easier to implement than software - reset. - </para> - </listitem> - </varlistentry> - - </variablelist> - - <para> - One more thing to consider when resetting devices is that - resetting clears certain configuration parameters and they - need to be set to their previous or newly adjusted values - after reset. - </para> - - <para> - Parameters affected are. - </para> - - <itemizedlist> - - <listitem> - <para> - CHS set up with INITIALIZE DEVICE PARAMETERS (seldom used) - </para> - </listitem> - - <listitem> - <para> - Parameters set with SET FEATURES including transfer mode setting - </para> - </listitem> - - <listitem> - <para> - Block count set with SET MULTIPLE MODE - </para> - </listitem> - - <listitem> - <para> - Other parameters (SET MAX, MEDIA LOCK...) - </para> - </listitem> - - </itemizedlist> - - <para> - ATA/ATAPI standard specifies that some parameters must be - maintained across hardware or software reset, but doesn't - strictly specify all of them. Always reconfiguring needed - parameters after reset is required for robustness. Note that - this also applies when resuming from deep sleep (power-off). - </para> - - <para> - Also, ATA/ATAPI standard requires that IDENTIFY DEVICE / - IDENTIFY PACKET DEVICE is issued after any configuration - parameter is updated or a hardware reset and the result used - for further operation. OS driver is required to implement - revalidation mechanism to support this. - </para> - - </sect2> - - <sect2 id="exrecReconf"> - <title>Reconfigure transport</title> - - <para> - For both PATA and SATA, a lot of corners are cut for cheap - connectors, cables or controllers and it's quite common to see - high transmission error rate. This can be mitigated by - lowering transmission speed. - </para> - - <para> - The following is a possible scheme Jeff Garzik suggested. - </para> - - <blockquote> - <para> - If more than $N (3?) transmission errors happen in 15 minutes, - </para> - <itemizedlist> - <listitem> - <para> - if SATA, decrease SATA PHY speed. if speed cannot be decreased, - </para> - </listitem> - <listitem> - <para> - decrease UDMA xfer speed. if at UDMA0, switch to PIO4, - </para> - </listitem> - <listitem> - <para> - decrease PIO xfer speed. if at PIO3, complain, but continue - </para> - </listitem> - </itemizedlist> - </blockquote> - - </sect2> - - </sect1> - - </chapter> - - <chapter id="PiixInt"> - <title>ata_piix Internals</title> -!Idrivers/ata/ata_piix.c - </chapter> - - <chapter id="SILInt"> - <title>sata_sil Internals</title> -!Idrivers/ata/sata_sil.c - </chapter> - - <chapter id="libataThanks"> - <title>Thanks</title> - <para> - The bulk of the ATA knowledge comes thanks to long conversations with - Andre Hedrick (www.linux-ide.org), and long hours pondering the ATA - and SCSI specifications. - </para> - <para> - Thanks to Alan Cox for pointing out similarities - between SATA and SCSI, and in general for motivation to hack on - libata. - </para> - <para> - libata's device detection - method, ata_pio_devchk, and in general all the early probing was - based on extensive study of Hale Landis's probe/reset code in his - ATADRVR driver (www.ata-atapi.com). - </para> - </chapter> - -</book> diff --git a/Documentation/DocBook/librs.tmpl b/Documentation/DocBook/librs.tmpl deleted file mode 100644 index 94f21361e0ed..000000000000 --- a/Documentation/DocBook/librs.tmpl +++ /dev/null @@ -1,289 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="Reed-Solomon-Library-Guide"> - <bookinfo> - <title>Reed-Solomon Library Programming Interface</title> - - <authorgroup> - <author> - <firstname>Thomas</firstname> - <surname>Gleixner</surname> - <affiliation> - <address> - <email>tglx@linutronix.de</email> - </address> - </affiliation> - </author> - </authorgroup> - - <copyright> - <year>2004</year> - <holder>Thomas Gleixner</holder> - </copyright> - - <legalnotice> - <para> - This documentation is free software; you can redistribute - it and/or modify it under the terms of the GNU General Public - License version 2 as published by the Free Software Foundation. - </para> - - <para> - This program is distributed in the hope that it will be - useful, but WITHOUT ANY WARRANTY; without even the implied - warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. - See the GNU General Public License for more details. - </para> - - <para> - You should have received a copy of the GNU General Public - License along with this program; if not, write to the Free - Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, - MA 02111-1307 USA - </para> - - <para> - For more details see the file COPYING in the source - distribution of Linux. - </para> - </legalnotice> - </bookinfo> - -<toc></toc> - - <chapter id="intro"> - <title>Introduction</title> - <para> - The generic Reed-Solomon Library provides encoding, decoding - and error correction functions. - </para> - <para> - Reed-Solomon codes are used in communication and storage - applications to ensure data integrity. - </para> - <para> - This documentation is provided for developers who want to utilize - the functions provided by the library. - </para> - </chapter> - - <chapter id="bugs"> - <title>Known Bugs And Assumptions</title> - <para> - None. - </para> - </chapter> - - <chapter id="usage"> - <title>Usage</title> - <para> - This chapter provides examples of how to use the library. - </para> - <sect1> - <title>Initializing</title> - <para> - The init function init_rs returns a pointer to an - rs decoder structure, which holds the necessary - information for encoding, decoding and error correction - with the given polynomial. It either uses an existing - matching decoder or creates a new one. On creation all - the lookup tables for fast en/decoding are created. - The function may take a while, so make sure not to - call it in critical code paths. - </para> - <programlisting> -/* the Reed Solomon control structure */ -static struct rs_control *rs_decoder; - -/* Symbolsize is 10 (bits) - * Primitive polynomial is x^10+x^3+1 - * first consecutive root is 0 - * primitive element to generate roots = 1 - * generator polynomial degree (number of roots) = 6 - */ -rs_decoder = init_rs (10, 0x409, 0, 1, 6); - </programlisting> - </sect1> - <sect1> - <title>Encoding</title> - <para> - The encoder calculates the Reed-Solomon code over - the given data length and stores the result in - the parity buffer. Note that the parity buffer must - be initialized before calling the encoder. - </para> - <para> - The expanded data can be inverted on the fly by - providing a non-zero inversion mask. The expanded data is - XOR'ed with the mask. This is used e.g. for FLASH - ECC, where the all 0xFF is inverted to an all 0x00. - The Reed-Solomon code for all 0x00 is all 0x00. The - code is inverted before storing to FLASH so it is 0xFF - too. This prevents that reading from an erased FLASH - results in ECC errors. - </para> - <para> - The databytes are expanded to the given symbol size - on the fly. There is no support for encoding continuous - bitstreams with a symbol size != 8 at the moment. If - it is necessary it should be not a big deal to implement - such functionality. - </para> - <programlisting> -/* Parity buffer. Size = number of roots */ -uint16_t par[6]; -/* Initialize the parity buffer */ -memset(par, 0, sizeof(par)); -/* Encode 512 byte in data8. Store parity in buffer par */ -encode_rs8 (rs_decoder, data8, 512, par, 0); - </programlisting> - </sect1> - <sect1> - <title>Decoding</title> - <para> - The decoder calculates the syndrome over - the given data length and the received parity symbols - and corrects errors in the data. - </para> - <para> - If a syndrome is available from a hardware decoder - then the syndrome calculation is skipped. - </para> - <para> - The correction of the data buffer can be suppressed - by providing a correction pattern buffer and an error - location buffer to the decoder. The decoder stores the - calculated error location and the correction bitmask - in the given buffers. This is useful for hardware - decoders which use a weird bit ordering scheme. - </para> - <para> - The databytes are expanded to the given symbol size - on the fly. There is no support for decoding continuous - bitstreams with a symbolsize != 8 at the moment. If - it is necessary it should be not a big deal to implement - such functionality. - </para> - - <sect2> - <title> - Decoding with syndrome calculation, direct data correction - </title> - <programlisting> -/* Parity buffer. Size = number of roots */ -uint16_t par[6]; -uint8_t data[512]; -int numerr; -/* Receive data */ -..... -/* Receive parity */ -..... -/* Decode 512 byte in data8.*/ -numerr = decode_rs8 (rs_decoder, data8, par, 512, NULL, 0, NULL, 0, NULL); - </programlisting> - </sect2> - - <sect2> - <title> - Decoding with syndrome given by hardware decoder, direct data correction - </title> - <programlisting> -/* Parity buffer. Size = number of roots */ -uint16_t par[6], syn[6]; -uint8_t data[512]; -int numerr; -/* Receive data */ -..... -/* Receive parity */ -..... -/* Get syndrome from hardware decoder */ -..... -/* Decode 512 byte in data8.*/ -numerr = decode_rs8 (rs_decoder, data8, par, 512, syn, 0, NULL, 0, NULL); - </programlisting> - </sect2> - - <sect2> - <title> - Decoding with syndrome given by hardware decoder, no direct data correction. - </title> - <para> - Note: It's not necessary to give data and received parity to the decoder. - </para> - <programlisting> -/* Parity buffer. Size = number of roots */ -uint16_t par[6], syn[6], corr[8]; -uint8_t data[512]; -int numerr, errpos[8]; -/* Receive data */ -..... -/* Receive parity */ -..... -/* Get syndrome from hardware decoder */ -..... -/* Decode 512 byte in data8.*/ -numerr = decode_rs8 (rs_decoder, NULL, NULL, 512, syn, 0, errpos, 0, corr); -for (i = 0; i < numerr; i++) { - do_error_correction_in_your_buffer(errpos[i], corr[i]); -} - </programlisting> - </sect2> - </sect1> - <sect1> - <title>Cleanup</title> - <para> - The function free_rs frees the allocated resources, - if the caller is the last user of the decoder. - </para> - <programlisting> -/* Release resources */ -free_rs(rs_decoder); - </programlisting> - </sect1> - - </chapter> - - <chapter id="structs"> - <title>Structures</title> - <para> - This chapter contains the autogenerated documentation of the structures which are - used in the Reed-Solomon Library and are relevant for a developer. - </para> -!Iinclude/linux/rslib.h - </chapter> - - <chapter id="pubfunctions"> - <title>Public Functions Provided</title> - <para> - This chapter contains the autogenerated documentation of the Reed-Solomon functions - which are exported. - </para> -!Elib/reed_solomon/reed_solomon.c - </chapter> - - <chapter id="credits"> - <title>Credits</title> - <para> - The library code for encoding and decoding was written by Phil Karn. - </para> - <programlisting> - Copyright 2002, Phil Karn, KA9Q - May be used under the terms of the GNU General Public License (GPL) - </programlisting> - <para> - The wrapper functions and interfaces are written by Thomas Gleixner. - </para> - <para> - Many users have provided bugfixes, improvements and helping hands for testing. - Thanks a lot. - </para> - <para> - The following people have contributed to this document: - </para> - <para> - Thomas Gleixner<email>tglx@linutronix.de</email> - </para> - </chapter> -</book> diff --git a/Documentation/DocBook/lsm.tmpl b/Documentation/DocBook/lsm.tmpl deleted file mode 100644 index fe7664ce9667..000000000000 --- a/Documentation/DocBook/lsm.tmpl +++ /dev/null @@ -1,265 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<article class="whitepaper" id="LinuxSecurityModule" lang="en"> - <articleinfo> - <title>Linux Security Modules: General Security Hooks for Linux</title> - <authorgroup> - <author> - <firstname>Stephen</firstname> - <surname>Smalley</surname> - <affiliation> - <orgname>NAI Labs</orgname> - <address><email>ssmalley@nai.com</email></address> - </affiliation> - </author> - <author> - <firstname>Timothy</firstname> - <surname>Fraser</surname> - <affiliation> - <orgname>NAI Labs</orgname> - <address><email>tfraser@nai.com</email></address> - </affiliation> - </author> - <author> - <firstname>Chris</firstname> - <surname>Vance</surname> - <affiliation> - <orgname>NAI Labs</orgname> - <address><email>cvance@nai.com</email></address> - </affiliation> - </author> - </authorgroup> - </articleinfo> - -<sect1 id="Introduction"><title>Introduction</title> - -<para> -In March 2001, the National Security Agency (NSA) gave a presentation -about Security-Enhanced Linux (SELinux) at the 2.5 Linux Kernel -Summit. SELinux is an implementation of flexible and fine-grained -nondiscretionary access controls in the Linux kernel, originally -implemented as its own particular kernel patch. Several other -security projects (e.g. RSBAC, Medusa) have also developed flexible -access control architectures for the Linux kernel, and various -projects have developed particular access control models for Linux -(e.g. LIDS, DTE, SubDomain). Each project has developed and -maintained its own kernel patch to support its security needs. -</para> - -<para> -In response to the NSA presentation, Linus Torvalds made a set of -remarks that described a security framework he would be willing to -consider for inclusion in the mainstream Linux kernel. He described a -general framework that would provide a set of security hooks to -control operations on kernel objects and a set of opaque security -fields in kernel data structures for maintaining security attributes. -This framework could then be used by loadable kernel modules to -implement any desired model of security. Linus also suggested the -possibility of migrating the Linux capabilities code into such a -module. -</para> - -<para> -The Linux Security Modules (LSM) project was started by WireX to -develop such a framework. LSM is a joint development effort by -several security projects, including Immunix, SELinux, SGI and Janus, -and several individuals, including Greg Kroah-Hartman and James -Morris, to develop a Linux kernel patch that implements this -framework. The patch is currently tracking the 2.4 series and is -targeted for integration into the 2.5 development series. This -technical report provides an overview of the framework and the example -capabilities security module provided by the LSM kernel patch. -</para> - -</sect1> - -<sect1 id="framework"><title>LSM Framework</title> - -<para> -The LSM kernel patch provides a general kernel framework to support -security modules. In particular, the LSM framework is primarily -focused on supporting access control modules, although future -development is likely to address other security needs such as -auditing. By itself, the framework does not provide any additional -security; it merely provides the infrastructure to support security -modules. The LSM kernel patch also moves most of the capabilities -logic into an optional security module, with the system defaulting -to the traditional superuser logic. This capabilities module -is discussed further in <xref linkend="cap"/>. -</para> - -<para> -The LSM kernel patch adds security fields to kernel data structures -and inserts calls to hook functions at critical points in the kernel -code to manage the security fields and to perform access control. It -also adds functions for registering and unregistering security -modules, and adds a general <function>security</function> system call -to support new system calls for security-aware applications. -</para> - -<para> -The LSM security fields are simply <type>void*</type> pointers. For -process and program execution security information, security fields -were added to <structname>struct task_struct</structname> and -<structname>struct linux_binprm</structname>. For filesystem security -information, a security field was added to -<structname>struct super_block</structname>. For pipe, file, and socket -security information, security fields were added to -<structname>struct inode</structname> and -<structname>struct file</structname>. For packet and network device security -information, security fields were added to -<structname>struct sk_buff</structname> and -<structname>struct net_device</structname>. For System V IPC security -information, security fields were added to -<structname>struct kern_ipc_perm</structname> and -<structname>struct msg_msg</structname>; additionally, the definitions -for <structname>struct msg_msg</structname>, <structname>struct -msg_queue</structname>, and <structname>struct -shmid_kernel</structname> were moved to header files -(<filename>include/linux/msg.h</filename> and -<filename>include/linux/shm.h</filename> as appropriate) to allow -the security modules to use these definitions. -</para> - -<para> -Each LSM hook is a function pointer in a global table, -security_ops. This table is a -<structname>security_operations</structname> structure as defined by -<filename>include/linux/security.h</filename>. Detailed documentation -for each hook is included in this header file. At present, this -structure consists of a collection of substructures that group related -hooks based on the kernel object (e.g. task, inode, file, sk_buff, -etc) as well as some top-level hook function pointers for system -operations. This structure is likely to be flattened in the future -for performance. The placement of the hook calls in the kernel code -is described by the "called:" lines in the per-hook documentation in -the header file. The hook calls can also be easily found in the -kernel code by looking for the string "security_ops->". - -</para> - -<para> -Linus mentioned per-process security hooks in his original remarks as a -possible alternative to global security hooks. However, if LSM were -to start from the perspective of per-process hooks, then the base -framework would have to deal with how to handle operations that -involve multiple processes (e.g. kill), since each process might have -its own hook for controlling the operation. This would require a -general mechanism for composing hooks in the base framework. -Additionally, LSM would still need global hooks for operations that -have no process context (e.g. network input operations). -Consequently, LSM provides global security hooks, but a security -module is free to implement per-process hooks (where that makes sense) -by storing a security_ops table in each process' security field and -then invoking these per-process hooks from the global hooks. -The problem of composition is thus deferred to the module. -</para> - -<para> -The global security_ops table is initialized to a set of hook -functions provided by a dummy security module that provides -traditional superuser logic. A <function>register_security</function> -function (in <filename>security/security.c</filename>) is provided to -allow a security module to set security_ops to refer to its own hook -functions, and an <function>unregister_security</function> function is -provided to revert security_ops to the dummy module hooks. This -mechanism is used to set the primary security module, which is -responsible for making the final decision for each hook. -</para> - -<para> -LSM also provides a simple mechanism for stacking additional security -modules with the primary security module. It defines -<function>register_security</function> and -<function>unregister_security</function> hooks in the -<structname>security_operations</structname> structure and provides -<function>mod_reg_security</function> and -<function>mod_unreg_security</function> functions that invoke these -hooks after performing some sanity checking. A security module can -call these functions in order to stack with other modules. However, -the actual details of how this stacking is handled are deferred to the -module, which can implement these hooks in any way it wishes -(including always returning an error if it does not wish to support -stacking). In this manner, LSM again defers the problem of -composition to the module. -</para> - -<para> -Although the LSM hooks are organized into substructures based on -kernel object, all of the hooks can be viewed as falling into two -major categories: hooks that are used to manage the security fields -and hooks that are used to perform access control. Examples of the -first category of hooks include the -<function>alloc_security</function> and -<function>free_security</function> hooks defined for each kernel data -structure that has a security field. These hooks are used to allocate -and free security structures for kernel objects. The first category -of hooks also includes hooks that set information in the security -field after allocation, such as the <function>post_lookup</function> -hook in <structname>struct inode_security_ops</structname>. This hook -is used to set security information for inodes after successful lookup -operations. An example of the second category of hooks is the -<function>permission</function> hook in -<structname>struct inode_security_ops</structname>. This hook checks -permission when accessing an inode. -</para> - -</sect1> - -<sect1 id="cap"><title>LSM Capabilities Module</title> - -<para> -The LSM kernel patch moves most of the existing POSIX.1e capabilities -logic into an optional security module stored in the file -<filename>security/capability.c</filename>. This change allows -users who do not want to use capabilities to omit this code entirely -from their kernel, instead using the dummy module for traditional -superuser logic or any other module that they desire. This change -also allows the developers of the capabilities logic to maintain and -enhance their code more freely, without needing to integrate patches -back into the base kernel. -</para> - -<para> -In addition to moving the capabilities logic, the LSM kernel patch -could move the capability-related fields from the kernel data -structures into the new security fields managed by the security -modules. However, at present, the LSM kernel patch leaves the -capability fields in the kernel data structures. In his original -remarks, Linus suggested that this might be preferable so that other -security modules can be easily stacked with the capabilities module -without needing to chain multiple security structures on the security field. -It also avoids imposing extra overhead on the capabilities module -to manage the security fields. However, the LSM framework could -certainly support such a move if it is determined to be desirable, -with only a few additional changes described below. -</para> - -<para> -At present, the capabilities logic for computing process capabilities -on <function>execve</function> and <function>set*uid</function>, -checking capabilities for a particular process, saving and checking -capabilities for netlink messages, and handling the -<function>capget</function> and <function>capset</function> system -calls have been moved into the capabilities module. There are still a -few locations in the base kernel where capability-related fields are -directly examined or modified, but the current version of the LSM -patch does allow a security module to completely replace the -assignment and testing of capabilities. These few locations would -need to be changed if the capability-related fields were moved into -the security field. The following is a list of known locations that -still perform such direct examination or modification of -capability-related fields: -<itemizedlist> -<listitem><para><filename>fs/open.c</filename>:<function>sys_access</function></para></listitem> -<listitem><para><filename>fs/lockd/host.c</filename>:<function>nlm_bind_host</function></para></listitem> -<listitem><para><filename>fs/nfsd/auth.c</filename>:<function>nfsd_setuser</function></para></listitem> -<listitem><para><filename>fs/proc/array.c</filename>:<function>task_cap</function></para></listitem> -</itemizedlist> -</para> - -</sect1> - -</article> diff --git a/Documentation/DocBook/mtdnand.tmpl b/Documentation/DocBook/mtdnand.tmpl deleted file mode 100644 index b442921bca54..000000000000 --- a/Documentation/DocBook/mtdnand.tmpl +++ /dev/null @@ -1,1291 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="MTD-NAND-Guide"> - <bookinfo> - <title>MTD NAND Driver Programming Interface</title> - - <authorgroup> - <author> - <firstname>Thomas</firstname> - <surname>Gleixner</surname> - <affiliation> - <address> - <email>tglx@linutronix.de</email> - </address> - </affiliation> - </author> - </authorgroup> - - <copyright> - <year>2004</year> - <holder>Thomas Gleixner</holder> - </copyright> - - <legalnotice> - <para> - This documentation is free software; you can redistribute - it and/or modify it under the terms of the GNU General Public - License version 2 as published by the Free Software Foundation. - </para> - - <para> - This program is distributed in the hope that it will be - useful, but WITHOUT ANY WARRANTY; without even the implied - warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. - See the GNU General Public License for more details. - </para> - - <para> - You should have received a copy of the GNU General Public - License along with this program; if not, write to the Free - Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, - MA 02111-1307 USA - </para> - - <para> - For more details see the file COPYING in the source - distribution of Linux. - </para> - </legalnotice> - </bookinfo> - -<toc></toc> - - <chapter id="intro"> - <title>Introduction</title> - <para> - The generic NAND driver supports almost all NAND and AG-AND based - chips and connects them to the Memory Technology Devices (MTD) - subsystem of the Linux Kernel. - </para> - <para> - This documentation is provided for developers who want to implement - board drivers or filesystem drivers suitable for NAND devices. - </para> - </chapter> - - <chapter id="bugs"> - <title>Known Bugs And Assumptions</title> - <para> - None. - </para> - </chapter> - - <chapter id="dochints"> - <title>Documentation hints</title> - <para> - The function and structure docs are autogenerated. Each function and - struct member has a short description which is marked with an [XXX] identifier. - The following chapters explain the meaning of those identifiers. - </para> - <sect1 id="Function_identifiers_XXX"> - <title>Function identifiers [XXX]</title> - <para> - The functions are marked with [XXX] identifiers in the short - comment. The identifiers explain the usage and scope of the - functions. Following identifiers are used: - </para> - <itemizedlist> - <listitem><para> - [MTD Interface]</para><para> - These functions provide the interface to the MTD kernel API. - They are not replaceable and provide functionality - which is complete hardware independent. - </para></listitem> - <listitem><para> - [NAND Interface]</para><para> - These functions are exported and provide the interface to the NAND kernel API. - </para></listitem> - <listitem><para> - [GENERIC]</para><para> - Generic functions are not replaceable and provide functionality - which is complete hardware independent. - </para></listitem> - <listitem><para> - [DEFAULT]</para><para> - Default functions provide hardware related functionality which is suitable - for most of the implementations. These functions can be replaced by the - board driver if necessary. Those functions are called via pointers in the - NAND chip description structure. The board driver can set the functions which - should be replaced by board dependent functions before calling nand_scan(). - If the function pointer is NULL on entry to nand_scan() then the pointer - is set to the default function which is suitable for the detected chip type. - </para></listitem> - </itemizedlist> - </sect1> - <sect1 id="Struct_member_identifiers_XXX"> - <title>Struct member identifiers [XXX]</title> - <para> - The struct members are marked with [XXX] identifiers in the - comment. The identifiers explain the usage and scope of the - members. Following identifiers are used: - </para> - <itemizedlist> - <listitem><para> - [INTERN]</para><para> - These members are for NAND driver internal use only and must not be - modified. Most of these values are calculated from the chip geometry - information which is evaluated during nand_scan(). - </para></listitem> - <listitem><para> - [REPLACEABLE]</para><para> - Replaceable members hold hardware related functions which can be - provided by the board driver. The board driver can set the functions which - should be replaced by board dependent functions before calling nand_scan(). - If the function pointer is NULL on entry to nand_scan() then the pointer - is set to the default function which is suitable for the detected chip type. - </para></listitem> - <listitem><para> - [BOARDSPECIFIC]</para><para> - Board specific members hold hardware related information which must - be provided by the board driver. The board driver must set the function - pointers and datafields before calling nand_scan(). - </para></listitem> - <listitem><para> - [OPTIONAL]</para><para> - Optional members can hold information relevant for the board driver. The - generic NAND driver code does not use this information. - </para></listitem> - </itemizedlist> - </sect1> - </chapter> - - <chapter id="basicboarddriver"> - <title>Basic board driver</title> - <para> - For most boards it will be sufficient to provide just the - basic functions and fill out some really board dependent - members in the nand chip description structure. - </para> - <sect1 id="Basic_defines"> - <title>Basic defines</title> - <para> - At least you have to provide a nand_chip structure - and a storage for the ioremap'ed chip address. - You can allocate the nand_chip structure using - kmalloc or you can allocate it statically. - The NAND chip structure embeds an mtd structure - which will be registered to the MTD subsystem. - You can extract a pointer to the mtd structure - from a nand_chip pointer using the nand_to_mtd() - helper. - </para> - <para> - Kmalloc based example - </para> - <programlisting> -static struct mtd_info *board_mtd; -static void __iomem *baseaddr; - </programlisting> - <para> - Static example - </para> - <programlisting> -static struct nand_chip board_chip; -static void __iomem *baseaddr; - </programlisting> - </sect1> - <sect1 id="Partition_defines"> - <title>Partition defines</title> - <para> - If you want to divide your device into partitions, then - define a partitioning scheme suitable to your board. - </para> - <programlisting> -#define NUM_PARTITIONS 2 -static struct mtd_partition partition_info[] = { - { .name = "Flash partition 1", - .offset = 0, - .size = 8 * 1024 * 1024 }, - { .name = "Flash partition 2", - .offset = MTDPART_OFS_NEXT, - .size = MTDPART_SIZ_FULL }, -}; - </programlisting> - </sect1> - <sect1 id="Hardware_control_functions"> - <title>Hardware control function</title> - <para> - The hardware control function provides access to the - control pins of the NAND chip(s). - The access can be done by GPIO pins or by address lines. - If you use address lines, make sure that the timing - requirements are met. - </para> - <para> - <emphasis>GPIO based example</emphasis> - </para> - <programlisting> -static void board_hwcontrol(struct mtd_info *mtd, int cmd) -{ - switch(cmd){ - case NAND_CTL_SETCLE: /* Set CLE pin high */ break; - case NAND_CTL_CLRCLE: /* Set CLE pin low */ break; - case NAND_CTL_SETALE: /* Set ALE pin high */ break; - case NAND_CTL_CLRALE: /* Set ALE pin low */ break; - case NAND_CTL_SETNCE: /* Set nCE pin low */ break; - case NAND_CTL_CLRNCE: /* Set nCE pin high */ break; - } -} - </programlisting> - <para> - <emphasis>Address lines based example.</emphasis> It's assumed that the - nCE pin is driven by a chip select decoder. - </para> - <programlisting> -static void board_hwcontrol(struct mtd_info *mtd, int cmd) -{ - struct nand_chip *this = mtd_to_nand(mtd); - switch(cmd){ - case NAND_CTL_SETCLE: this->IO_ADDR_W |= CLE_ADRR_BIT; break; - case NAND_CTL_CLRCLE: this->IO_ADDR_W &= ~CLE_ADRR_BIT; break; - case NAND_CTL_SETALE: this->IO_ADDR_W |= ALE_ADRR_BIT; break; - case NAND_CTL_CLRALE: this->IO_ADDR_W &= ~ALE_ADRR_BIT; break; - } -} - </programlisting> - </sect1> - <sect1 id="Device_ready_function"> - <title>Device ready function</title> - <para> - If the hardware interface has the ready busy pin of the NAND chip connected to a - GPIO or other accessible I/O pin, this function is used to read back the state of the - pin. The function has no arguments and should return 0, if the device is busy (R/B pin - is low) and 1, if the device is ready (R/B pin is high). - If the hardware interface does not give access to the ready busy pin, then - the function must not be defined and the function pointer this->dev_ready is set to NULL. - </para> - </sect1> - <sect1 id="Init_function"> - <title>Init function</title> - <para> - The init function allocates memory and sets up all the board - specific parameters and function pointers. When everything - is set up nand_scan() is called. This function tries to - detect and identify then chip. If a chip is found all the - internal data fields are initialized accordingly. - The structure(s) have to be zeroed out first and then filled with the necessary - information about the device. - </para> - <programlisting> -static int __init board_init (void) -{ - struct nand_chip *this; - int err = 0; - - /* Allocate memory for MTD device structure and private data */ - this = kzalloc(sizeof(struct nand_chip), GFP_KERNEL); - if (!this) { - printk ("Unable to allocate NAND MTD device structure.\n"); - err = -ENOMEM; - goto out; - } - - board_mtd = nand_to_mtd(this); - - /* map physical address */ - baseaddr = ioremap(CHIP_PHYSICAL_ADDRESS, 1024); - if (!baseaddr) { - printk("Ioremap to access NAND chip failed\n"); - err = -EIO; - goto out_mtd; - } - - /* Set address of NAND IO lines */ - this->IO_ADDR_R = baseaddr; - this->IO_ADDR_W = baseaddr; - /* Reference hardware control function */ - this->hwcontrol = board_hwcontrol; - /* Set command delay time, see datasheet for correct value */ - this->chip_delay = CHIP_DEPENDEND_COMMAND_DELAY; - /* Assign the device ready function, if available */ - this->dev_ready = board_dev_ready; - this->eccmode = NAND_ECC_SOFT; - - /* Scan to find existence of the device */ - if (nand_scan (board_mtd, 1)) { - err = -ENXIO; - goto out_ior; - } - - add_mtd_partitions(board_mtd, partition_info, NUM_PARTITIONS); - goto out; - -out_ior: - iounmap(baseaddr); -out_mtd: - kfree (this); -out: - return err; -} -module_init(board_init); - </programlisting> - </sect1> - <sect1 id="Exit_function"> - <title>Exit function</title> - <para> - The exit function is only necessary if the driver is - compiled as a module. It releases all resources which - are held by the chip driver and unregisters the partitions - in the MTD layer. - </para> - <programlisting> -#ifdef MODULE -static void __exit board_cleanup (void) -{ - /* Release resources, unregister device */ - nand_release (board_mtd); - - /* unmap physical address */ - iounmap(baseaddr); - - /* Free the MTD device structure */ - kfree (mtd_to_nand(board_mtd)); -} -module_exit(board_cleanup); -#endif - </programlisting> - </sect1> - </chapter> - - <chapter id="boarddriversadvanced"> - <title>Advanced board driver functions</title> - <para> - This chapter describes the advanced functionality of the NAND - driver. For a list of functions which can be overridden by the board - driver see the documentation of the nand_chip structure. - </para> - <sect1 id="Multiple_chip_control"> - <title>Multiple chip control</title> - <para> - The nand driver can control chip arrays. Therefore the - board driver must provide an own select_chip function. This - function must (de)select the requested chip. - The function pointer in the nand_chip structure must - be set before calling nand_scan(). The maxchip parameter - of nand_scan() defines the maximum number of chips to - scan for. Make sure that the select_chip function can - handle the requested number of chips. - </para> - <para> - The nand driver concatenates the chips to one virtual - chip and provides this virtual chip to the MTD layer. - </para> - <para> - <emphasis>Note: The driver can only handle linear chip arrays - of equally sized chips. There is no support for - parallel arrays which extend the buswidth.</emphasis> - </para> - <para> - <emphasis>GPIO based example</emphasis> - </para> - <programlisting> -static void board_select_chip (struct mtd_info *mtd, int chip) -{ - /* Deselect all chips, set all nCE pins high */ - GPIO(BOARD_NAND_NCE) |= 0xff; - if (chip >= 0) - GPIO(BOARD_NAND_NCE) &= ~ (1 << chip); -} - </programlisting> - <para> - <emphasis>Address lines based example.</emphasis> - Its assumed that the nCE pins are connected to an - address decoder. - </para> - <programlisting> -static void board_select_chip (struct mtd_info *mtd, int chip) -{ - struct nand_chip *this = mtd_to_nand(mtd); - - /* Deselect all chips */ - this->IO_ADDR_R &= ~BOARD_NAND_ADDR_MASK; - this->IO_ADDR_W &= ~BOARD_NAND_ADDR_MASK; - switch (chip) { - case 0: - this->IO_ADDR_R |= BOARD_NAND_ADDR_CHIP0; - this->IO_ADDR_W |= BOARD_NAND_ADDR_CHIP0; - break; - .... - case n: - this->IO_ADDR_R |= BOARD_NAND_ADDR_CHIPn; - this->IO_ADDR_W |= BOARD_NAND_ADDR_CHIPn; - break; - } -} - </programlisting> - </sect1> - <sect1 id="Hardware_ECC_support"> - <title>Hardware ECC support</title> - <sect2 id="Functions_and_constants"> - <title>Functions and constants</title> - <para> - The nand driver supports three different types of - hardware ECC. - <itemizedlist> - <listitem><para>NAND_ECC_HW3_256</para><para> - Hardware ECC generator providing 3 bytes ECC per - 256 byte. - </para> </listitem> - <listitem><para>NAND_ECC_HW3_512</para><para> - Hardware ECC generator providing 3 bytes ECC per - 512 byte. - </para> </listitem> - <listitem><para>NAND_ECC_HW6_512</para><para> - Hardware ECC generator providing 6 bytes ECC per - 512 byte. - </para> </listitem> - <listitem><para>NAND_ECC_HW8_512</para><para> - Hardware ECC generator providing 6 bytes ECC per - 512 byte. - </para> </listitem> - </itemizedlist> - If your hardware generator has a different functionality - add it at the appropriate place in nand_base.c - </para> - <para> - The board driver must provide following functions: - <itemizedlist> - <listitem><para>enable_hwecc</para><para> - This function is called before reading / writing to - the chip. Reset or initialize the hardware generator - in this function. The function is called with an - argument which let you distinguish between read - and write operations. - </para> </listitem> - <listitem><para>calculate_ecc</para><para> - This function is called after read / write from / to - the chip. Transfer the ECC from the hardware to - the buffer. If the option NAND_HWECC_SYNDROME is set - then the function is only called on write. See below. - </para> </listitem> - <listitem><para>correct_data</para><para> - In case of an ECC error this function is called for - error detection and correction. Return 1 respectively 2 - in case the error can be corrected. If the error is - not correctable return -1. If your hardware generator - matches the default algorithm of the nand_ecc software - generator then use the correction function provided - by nand_ecc instead of implementing duplicated code. - </para> </listitem> - </itemizedlist> - </para> - </sect2> - <sect2 id="Hardware_ECC_with_syndrome_calculation"> - <title>Hardware ECC with syndrome calculation</title> - <para> - Many hardware ECC implementations provide Reed-Solomon - codes and calculate an error syndrome on read. The syndrome - must be converted to a standard Reed-Solomon syndrome - before calling the error correction code in the generic - Reed-Solomon library. - </para> - <para> - The ECC bytes must be placed immediately after the data - bytes in order to make the syndrome generator work. This - is contrary to the usual layout used by software ECC. The - separation of data and out of band area is not longer - possible. The nand driver code handles this layout and - the remaining free bytes in the oob area are managed by - the autoplacement code. Provide a matching oob-layout - in this case. See rts_from4.c and diskonchip.c for - implementation reference. In those cases we must also - use bad block tables on FLASH, because the ECC layout is - interfering with the bad block marker positions. - See bad block table support for details. - </para> - </sect2> - </sect1> - <sect1 id="Bad_Block_table_support"> - <title>Bad block table support</title> - <para> - Most NAND chips mark the bad blocks at a defined - position in the spare area. Those blocks must - not be erased under any circumstances as the bad - block information would be lost. - It is possible to check the bad block mark each - time when the blocks are accessed by reading the - spare area of the first page in the block. This - is time consuming so a bad block table is used. - </para> - <para> - The nand driver supports various types of bad block - tables. - <itemizedlist> - <listitem><para>Per device</para><para> - The bad block table contains all bad block information - of the device which can consist of multiple chips. - </para> </listitem> - <listitem><para>Per chip</para><para> - A bad block table is used per chip and contains the - bad block information for this particular chip. - </para> </listitem> - <listitem><para>Fixed offset</para><para> - The bad block table is located at a fixed offset - in the chip (device). This applies to various - DiskOnChip devices. - </para> </listitem> - <listitem><para>Automatic placed</para><para> - The bad block table is automatically placed and - detected either at the end or at the beginning - of a chip (device) - </para> </listitem> - <listitem><para>Mirrored tables</para><para> - The bad block table is mirrored on the chip (device) to - allow updates of the bad block table without data loss. - </para> </listitem> - </itemizedlist> - </para> - <para> - nand_scan() calls the function nand_default_bbt(). - nand_default_bbt() selects appropriate default - bad block table descriptors depending on the chip information - which was retrieved by nand_scan(). - </para> - <para> - The standard policy is scanning the device for bad - blocks and build a ram based bad block table which - allows faster access than always checking the - bad block information on the flash chip itself. - </para> - <sect2 id="Flash_based_tables"> - <title>Flash based tables</title> - <para> - It may be desired or necessary to keep a bad block table in FLASH. - For AG-AND chips this is mandatory, as they have no factory marked - bad blocks. They have factory marked good blocks. The marker pattern - is erased when the block is erased to be reused. So in case of - powerloss before writing the pattern back to the chip this block - would be lost and added to the bad blocks. Therefore we scan the - chip(s) when we detect them the first time for good blocks and - store this information in a bad block table before erasing any - of the blocks. - </para> - <para> - The blocks in which the tables are stored are protected against - accidental access by marking them bad in the memory bad block - table. The bad block table management functions are allowed - to circumvent this protection. - </para> - <para> - The simplest way to activate the FLASH based bad block table support - is to set the option NAND_BBT_USE_FLASH in the bbt_option field of - the nand chip structure before calling nand_scan(). For AG-AND - chips is this done by default. - This activates the default FLASH based bad block table functionality - of the NAND driver. The default bad block table options are - <itemizedlist> - <listitem><para>Store bad block table per chip</para></listitem> - <listitem><para>Use 2 bits per block</para></listitem> - <listitem><para>Automatic placement at the end of the chip</para></listitem> - <listitem><para>Use mirrored tables with version numbers</para></listitem> - <listitem><para>Reserve 4 blocks at the end of the chip</para></listitem> - </itemizedlist> - </para> - </sect2> - <sect2 id="User_defined_tables"> - <title>User defined tables</title> - <para> - User defined tables are created by filling out a - nand_bbt_descr structure and storing the pointer in the - nand_chip structure member bbt_td before calling nand_scan(). - If a mirror table is necessary a second structure must be - created and a pointer to this structure must be stored - in bbt_md inside the nand_chip structure. If the bbt_md - member is set to NULL then only the main table is used - and no scan for the mirrored table is performed. - </para> - <para> - The most important field in the nand_bbt_descr structure - is the options field. The options define most of the - table properties. Use the predefined constants from - nand.h to define the options. - <itemizedlist> - <listitem><para>Number of bits per block</para> - <para>The supported number of bits is 1, 2, 4, 8.</para></listitem> - <listitem><para>Table per chip</para> - <para>Setting the constant NAND_BBT_PERCHIP selects that - a bad block table is managed for each chip in a chip array. - If this option is not set then a per device bad block table - is used.</para></listitem> - <listitem><para>Table location is absolute</para> - <para>Use the option constant NAND_BBT_ABSPAGE and - define the absolute page number where the bad block - table starts in the field pages. If you have selected bad block - tables per chip and you have a multi chip array then the start page - must be given for each chip in the chip array. Note: there is no scan - for a table ident pattern performed, so the fields - pattern, veroffs, offs, len can be left uninitialized</para></listitem> - <listitem><para>Table location is automatically detected</para> - <para>The table can either be located in the first or the last good - blocks of the chip (device). Set NAND_BBT_LASTBLOCK to place - the bad block table at the end of the chip (device). The - bad block tables are marked and identified by a pattern which - is stored in the spare area of the first page in the block which - holds the bad block table. Store a pointer to the pattern - in the pattern field. Further the length of the pattern has to be - stored in len and the offset in the spare area must be given - in the offs member of the nand_bbt_descr structure. For mirrored - bad block tables different patterns are mandatory.</para></listitem> - <listitem><para>Table creation</para> - <para>Set the option NAND_BBT_CREATE to enable the table creation - if no table can be found during the scan. Usually this is done only - once if a new chip is found. </para></listitem> - <listitem><para>Table write support</para> - <para>Set the option NAND_BBT_WRITE to enable the table write support. - This allows the update of the bad block table(s) in case a block has - to be marked bad due to wear. The MTD interface function block_markbad - is calling the update function of the bad block table. If the write - support is enabled then the table is updated on FLASH.</para> - <para> - Note: Write support should only be enabled for mirrored tables with - version control. - </para></listitem> - <listitem><para>Table version control</para> - <para>Set the option NAND_BBT_VERSION to enable the table version control. - It's highly recommended to enable this for mirrored tables with write - support. It makes sure that the risk of losing the bad block - table information is reduced to the loss of the information about the - one worn out block which should be marked bad. The version is stored in - 4 consecutive bytes in the spare area of the device. The position of - the version number is defined by the member veroffs in the bad block table - descriptor.</para></listitem> - <listitem><para>Save block contents on write</para> - <para> - In case that the block which holds the bad block table does contain - other useful information, set the option NAND_BBT_SAVECONTENT. When - the bad block table is written then the whole block is read the bad - block table is updated and the block is erased and everything is - written back. If this option is not set only the bad block table - is written and everything else in the block is ignored and erased. - </para></listitem> - <listitem><para>Number of reserved blocks</para> - <para> - For automatic placement some blocks must be reserved for - bad block table storage. The number of reserved blocks is defined - in the maxblocks member of the bad block table description structure. - Reserving 4 blocks for mirrored tables should be a reasonable number. - This also limits the number of blocks which are scanned for the bad - block table ident pattern. - </para></listitem> - </itemizedlist> - </para> - </sect2> - </sect1> - <sect1 id="Spare_area_placement"> - <title>Spare area (auto)placement</title> - <para> - The nand driver implements different possibilities for - placement of filesystem data in the spare area, - <itemizedlist> - <listitem><para>Placement defined by fs driver</para></listitem> - <listitem><para>Automatic placement</para></listitem> - </itemizedlist> - The default placement function is automatic placement. The - nand driver has built in default placement schemes for the - various chiptypes. If due to hardware ECC functionality the - default placement does not fit then the board driver can - provide a own placement scheme. - </para> - <para> - File system drivers can provide a own placement scheme which - is used instead of the default placement scheme. - </para> - <para> - Placement schemes are defined by a nand_oobinfo structure - <programlisting> -struct nand_oobinfo { - int useecc; - int eccbytes; - int eccpos[24]; - int oobfree[8][2]; -}; - </programlisting> - <itemizedlist> - <listitem><para>useecc</para><para> - The useecc member controls the ecc and placement function. The header - file include/mtd/mtd-abi.h contains constants to select ecc and - placement. MTD_NANDECC_OFF switches off the ecc complete. This is - not recommended and available for testing and diagnosis only. - MTD_NANDECC_PLACE selects caller defined placement, MTD_NANDECC_AUTOPLACE - selects automatic placement. - </para></listitem> - <listitem><para>eccbytes</para><para> - The eccbytes member defines the number of ecc bytes per page. - </para></listitem> - <listitem><para>eccpos</para><para> - The eccpos array holds the byte offsets in the spare area where - the ecc codes are placed. - </para></listitem> - <listitem><para>oobfree</para><para> - The oobfree array defines the areas in the spare area which can be - used for automatic placement. The information is given in the format - {offset, size}. offset defines the start of the usable area, size the - length in bytes. More than one area can be defined. The list is terminated - by an {0, 0} entry. - </para></listitem> - </itemizedlist> - </para> - <sect2 id="Placement_defined_by_fs_driver"> - <title>Placement defined by fs driver</title> - <para> - The calling function provides a pointer to a nand_oobinfo - structure which defines the ecc placement. For writes the - caller must provide a spare area buffer along with the - data buffer. The spare area buffer size is (number of pages) * - (size of spare area). For reads the buffer size is - (number of pages) * ((size of spare area) + (number of ecc - steps per page) * sizeof (int)). The driver stores the - result of the ecc check for each tuple in the spare buffer. - The storage sequence is - </para> - <para> - <spare data page 0><ecc result 0>...<ecc result n> - </para> - <para> - ... - </para> - <para> - <spare data page n><ecc result 0>...<ecc result n> - </para> - <para> - This is a legacy mode used by YAFFS1. - </para> - <para> - If the spare area buffer is NULL then only the ECC placement is - done according to the given scheme in the nand_oobinfo structure. - </para> - </sect2> - <sect2 id="Automatic_placement"> - <title>Automatic placement</title> - <para> - Automatic placement uses the built in defaults to place the - ecc bytes in the spare area. If filesystem data have to be stored / - read into the spare area then the calling function must provide a - buffer. The buffer size per page is determined by the oobfree array in - the nand_oobinfo structure. - </para> - <para> - If the spare area buffer is NULL then only the ECC placement is - done according to the default builtin scheme. - </para> - </sect2> - </sect1> - <sect1 id="Spare_area_autoplacement_default"> - <title>Spare area autoplacement default schemes</title> - <sect2 id="pagesize_256"> - <title>256 byte pagesize</title> -<informaltable><tgroup cols="3"><tbody> -<row> -<entry>Offset</entry> -<entry>Content</entry> -<entry>Comment</entry> -</row> -<row> -<entry>0x00</entry> -<entry>ECC byte 0</entry> -<entry>Error correction code byte 0</entry> -</row> -<row> -<entry>0x01</entry> -<entry>ECC byte 1</entry> -<entry>Error correction code byte 1</entry> -</row> -<row> -<entry>0x02</entry> -<entry>ECC byte 2</entry> -<entry>Error correction code byte 2</entry> -</row> -<row> -<entry>0x03</entry> -<entry>Autoplace 0</entry> -<entry></entry> -</row> -<row> -<entry>0x04</entry> -<entry>Autoplace 1</entry> -<entry></entry> -</row> -<row> -<entry>0x05</entry> -<entry>Bad block marker</entry> -<entry>If any bit in this byte is zero, then this block is bad. -This applies only to the first page in a block. In the remaining -pages this byte is reserved</entry> -</row> -<row> -<entry>0x06</entry> -<entry>Autoplace 2</entry> -<entry></entry> -</row> -<row> -<entry>0x07</entry> -<entry>Autoplace 3</entry> -<entry></entry> -</row> -</tbody></tgroup></informaltable> - </sect2> - <sect2 id="pagesize_512"> - <title>512 byte pagesize</title> -<informaltable><tgroup cols="3"><tbody> -<row> -<entry>Offset</entry> -<entry>Content</entry> -<entry>Comment</entry> -</row> -<row> -<entry>0x00</entry> -<entry>ECC byte 0</entry> -<entry>Error correction code byte 0 of the lower 256 Byte data in -this page</entry> -</row> -<row> -<entry>0x01</entry> -<entry>ECC byte 1</entry> -<entry>Error correction code byte 1 of the lower 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x02</entry> -<entry>ECC byte 2</entry> -<entry>Error correction code byte 2 of the lower 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x03</entry> -<entry>ECC byte 3</entry> -<entry>Error correction code byte 0 of the upper 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x04</entry> -<entry>reserved</entry> -<entry>reserved</entry> -</row> -<row> -<entry>0x05</entry> -<entry>Bad block marker</entry> -<entry>If any bit in this byte is zero, then this block is bad. -This applies only to the first page in a block. In the remaining -pages this byte is reserved</entry> -</row> -<row> -<entry>0x06</entry> -<entry>ECC byte 4</entry> -<entry>Error correction code byte 1 of the upper 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x07</entry> -<entry>ECC byte 5</entry> -<entry>Error correction code byte 2 of the upper 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x08 - 0x0F</entry> -<entry>Autoplace 0 - 7</entry> -<entry></entry> -</row> -</tbody></tgroup></informaltable> - </sect2> - <sect2 id="pagesize_2048"> - <title>2048 byte pagesize</title> -<informaltable><tgroup cols="3"><tbody> -<row> -<entry>Offset</entry> -<entry>Content</entry> -<entry>Comment</entry> -</row> -<row> -<entry>0x00</entry> -<entry>Bad block marker</entry> -<entry>If any bit in this byte is zero, then this block is bad. -This applies only to the first page in a block. In the remaining -pages this byte is reserved</entry> -</row> -<row> -<entry>0x01</entry> -<entry>Reserved</entry> -<entry>Reserved</entry> -</row> -<row> -<entry>0x02-0x27</entry> -<entry>Autoplace 0 - 37</entry> -<entry></entry> -</row> -<row> -<entry>0x28</entry> -<entry>ECC byte 0</entry> -<entry>Error correction code byte 0 of the first 256 Byte data in -this page</entry> -</row> -<row> -<entry>0x29</entry> -<entry>ECC byte 1</entry> -<entry>Error correction code byte 1 of the first 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x2A</entry> -<entry>ECC byte 2</entry> -<entry>Error correction code byte 2 of the first 256 Bytes data in -this page</entry> -</row> -<row> -<entry>0x2B</entry> -<entry>ECC byte 3</entry> -<entry>Error correction code byte 0 of the second 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x2C</entry> -<entry>ECC byte 4</entry> -<entry>Error correction code byte 1 of the second 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x2D</entry> -<entry>ECC byte 5</entry> -<entry>Error correction code byte 2 of the second 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x2E</entry> -<entry>ECC byte 6</entry> -<entry>Error correction code byte 0 of the third 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x2F</entry> -<entry>ECC byte 7</entry> -<entry>Error correction code byte 1 of the third 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x30</entry> -<entry>ECC byte 8</entry> -<entry>Error correction code byte 2 of the third 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x31</entry> -<entry>ECC byte 9</entry> -<entry>Error correction code byte 0 of the fourth 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x32</entry> -<entry>ECC byte 10</entry> -<entry>Error correction code byte 1 of the fourth 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x33</entry> -<entry>ECC byte 11</entry> -<entry>Error correction code byte 2 of the fourth 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x34</entry> -<entry>ECC byte 12</entry> -<entry>Error correction code byte 0 of the fifth 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x35</entry> -<entry>ECC byte 13</entry> -<entry>Error correction code byte 1 of the fifth 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x36</entry> -<entry>ECC byte 14</entry> -<entry>Error correction code byte 2 of the fifth 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x37</entry> -<entry>ECC byte 15</entry> -<entry>Error correction code byte 0 of the sixt 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x38</entry> -<entry>ECC byte 16</entry> -<entry>Error correction code byte 1 of the sixt 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x39</entry> -<entry>ECC byte 17</entry> -<entry>Error correction code byte 2 of the sixt 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x3A</entry> -<entry>ECC byte 18</entry> -<entry>Error correction code byte 0 of the seventh 256 Bytes of -data in this page</entry> -</row> -<row> -<entry>0x3B</entry> -<entry>ECC byte 19</entry> -<entry>Error correction code byte 1 of the seventh 256 Bytes of -data in this page</entry> -</row> -<row> -<entry>0x3C</entry> -<entry>ECC byte 20</entry> -<entry>Error correction code byte 2 of the seventh 256 Bytes of -data in this page</entry> -</row> -<row> -<entry>0x3D</entry> -<entry>ECC byte 21</entry> -<entry>Error correction code byte 0 of the eighth 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x3E</entry> -<entry>ECC byte 22</entry> -<entry>Error correction code byte 1 of the eighth 256 Bytes of data -in this page</entry> -</row> -<row> -<entry>0x3F</entry> -<entry>ECC byte 23</entry> -<entry>Error correction code byte 2 of the eighth 256 Bytes of data -in this page</entry> -</row> -</tbody></tgroup></informaltable> - </sect2> - </sect1> - </chapter> - - <chapter id="filesystems"> - <title>Filesystem support</title> - <para> - The NAND driver provides all necessary functions for a - filesystem via the MTD interface. - </para> - <para> - Filesystems must be aware of the NAND peculiarities and - restrictions. One major restrictions of NAND Flash is, that you cannot - write as often as you want to a page. The consecutive writes to a page, - before erasing it again, are restricted to 1-3 writes, depending on the - manufacturers specifications. This applies similar to the spare area. - </para> - <para> - Therefore NAND aware filesystems must either write in page size chunks - or hold a writebuffer to collect smaller writes until they sum up to - pagesize. Available NAND aware filesystems: JFFS2, YAFFS. - </para> - <para> - The spare area usage to store filesystem data is controlled by - the spare area placement functionality which is described in one - of the earlier chapters. - </para> - </chapter> - <chapter id="tools"> - <title>Tools</title> - <para> - The MTD project provides a couple of helpful tools to handle NAND Flash. - <itemizedlist> - <listitem><para>flasherase, flasheraseall: Erase and format FLASH partitions</para></listitem> - <listitem><para>nandwrite: write filesystem images to NAND FLASH</para></listitem> - <listitem><para>nanddump: dump the contents of a NAND FLASH partitions</para></listitem> - </itemizedlist> - </para> - <para> - These tools are aware of the NAND restrictions. Please use those tools - instead of complaining about errors which are caused by non NAND aware - access methods. - </para> - </chapter> - - <chapter id="defines"> - <title>Constants</title> - <para> - This chapter describes the constants which might be relevant for a driver developer. - </para> - <sect1 id="Chip_option_constants"> - <title>Chip option constants</title> - <sect2 id="Constants_for_chip_id_table"> - <title>Constants for chip id table</title> - <para> - These constants are defined in nand.h. They are ored together to describe - the chip functionality. - <programlisting> -/* Buswitdh is 16 bit */ -#define NAND_BUSWIDTH_16 0x00000002 -/* Device supports partial programming without padding */ -#define NAND_NO_PADDING 0x00000004 -/* Chip has cache program function */ -#define NAND_CACHEPRG 0x00000008 -/* Chip has copy back function */ -#define NAND_COPYBACK 0x00000010 -/* AND Chip which has 4 banks and a confusing page / block - * assignment. See Renesas datasheet for further information */ -#define NAND_IS_AND 0x00000020 -/* Chip has a array of 4 pages which can be read without - * additional ready /busy waits */ -#define NAND_4PAGE_ARRAY 0x00000040 - </programlisting> - </para> - </sect2> - <sect2 id="Constants_for_runtime_options"> - <title>Constants for runtime options</title> - <para> - These constants are defined in nand.h. They are ored together to describe - the functionality. - <programlisting> -/* The hw ecc generator provides a syndrome instead a ecc value on read - * This can only work if we have the ecc bytes directly behind the - * data bytes. Applies for DOC and AG-AND Renesas HW Reed Solomon generators */ -#define NAND_HWECC_SYNDROME 0x00020000 - </programlisting> - </para> - </sect2> - </sect1> - - <sect1 id="EEC_selection_constants"> - <title>ECC selection constants</title> - <para> - Use these constants to select the ECC algorithm. - <programlisting> -/* No ECC. Usage is not recommended ! */ -#define NAND_ECC_NONE 0 -/* Software ECC 3 byte ECC per 256 Byte data */ -#define NAND_ECC_SOFT 1 -/* Hardware ECC 3 byte ECC per 256 Byte data */ -#define NAND_ECC_HW3_256 2 -/* Hardware ECC 3 byte ECC per 512 Byte data */ -#define NAND_ECC_HW3_512 3 -/* Hardware ECC 6 byte ECC per 512 Byte data */ -#define NAND_ECC_HW6_512 4 -/* Hardware ECC 6 byte ECC per 512 Byte data */ -#define NAND_ECC_HW8_512 6 - </programlisting> - </para> - </sect1> - - <sect1 id="Hardware_control_related_constants"> - <title>Hardware control related constants</title> - <para> - These constants describe the requested hardware access function when - the boardspecific hardware control function is called - <programlisting> -/* Select the chip by setting nCE to low */ -#define NAND_CTL_SETNCE 1 -/* Deselect the chip by setting nCE to high */ -#define NAND_CTL_CLRNCE 2 -/* Select the command latch by setting CLE to high */ -#define NAND_CTL_SETCLE 3 -/* Deselect the command latch by setting CLE to low */ -#define NAND_CTL_CLRCLE 4 -/* Select the address latch by setting ALE to high */ -#define NAND_CTL_SETALE 5 -/* Deselect the address latch by setting ALE to low */ -#define NAND_CTL_CLRALE 6 -/* Set write protection by setting WP to high. Not used! */ -#define NAND_CTL_SETWP 7 -/* Clear write protection by setting WP to low. Not used! */ -#define NAND_CTL_CLRWP 8 - </programlisting> - </para> - </sect1> - - <sect1 id="Bad_block_table_constants"> - <title>Bad block table related constants</title> - <para> - These constants describe the options used for bad block - table descriptors. - <programlisting> -/* Options for the bad block table descriptors */ - -/* The number of bits used per block in the bbt on the device */ -#define NAND_BBT_NRBITS_MSK 0x0000000F -#define NAND_BBT_1BIT 0x00000001 -#define NAND_BBT_2BIT 0x00000002 -#define NAND_BBT_4BIT 0x00000004 -#define NAND_BBT_8BIT 0x00000008 -/* The bad block table is in the last good block of the device */ -#define NAND_BBT_LASTBLOCK 0x00000010 -/* The bbt is at the given page, else we must scan for the bbt */ -#define NAND_BBT_ABSPAGE 0x00000020 -/* bbt is stored per chip on multichip devices */ -#define NAND_BBT_PERCHIP 0x00000080 -/* bbt has a version counter at offset veroffs */ -#define NAND_BBT_VERSION 0x00000100 -/* Create a bbt if none axists */ -#define NAND_BBT_CREATE 0x00000200 -/* Write bbt if necessary */ -#define NAND_BBT_WRITE 0x00001000 -/* Read and write back block contents when writing bbt */ -#define NAND_BBT_SAVECONTENT 0x00002000 - </programlisting> - </para> - </sect1> - - </chapter> - - <chapter id="structs"> - <title>Structures</title> - <para> - This chapter contains the autogenerated documentation of the structures which are - used in the NAND driver and might be relevant for a driver developer. Each - struct member has a short description which is marked with an [XXX] identifier. - See the chapter "Documentation hints" for an explanation. - </para> -!Iinclude/linux/mtd/nand.h - </chapter> - - <chapter id="pubfunctions"> - <title>Public Functions Provided</title> - <para> - This chapter contains the autogenerated documentation of the NAND kernel API functions - which are exported. Each function has a short description which is marked with an [XXX] identifier. - See the chapter "Documentation hints" for an explanation. - </para> -!Edrivers/mtd/nand/nand_base.c -!Edrivers/mtd/nand/nand_bbt.c -!Edrivers/mtd/nand/nand_ecc.c - </chapter> - - <chapter id="intfunctions"> - <title>Internal Functions Provided</title> - <para> - This chapter contains the autogenerated documentation of the NAND driver internal functions. - Each function has a short description which is marked with an [XXX] identifier. - See the chapter "Documentation hints" for an explanation. - The functions marked with [DEFAULT] might be relevant for a board driver developer. - </para> -!Idrivers/mtd/nand/nand_base.c -!Idrivers/mtd/nand/nand_bbt.c -<!-- No internal functions for kernel-doc: -X!Idrivers/mtd/nand/nand_ecc.c ---> - </chapter> - - <chapter id="credits"> - <title>Credits</title> - <para> - The following people have contributed to the NAND driver: - <orderedlist> - <listitem><para>Steven J. Hill<email>sjhill@realitydiluted.com</email></para></listitem> - <listitem><para>David Woodhouse<email>dwmw2@infradead.org</email></para></listitem> - <listitem><para>Thomas Gleixner<email>tglx@linutronix.de</email></para></listitem> - </orderedlist> - A lot of users have provided bugfixes, improvements and helping hands for testing. - Thanks a lot. - </para> - <para> - The following people have contributed to this document: - <orderedlist> - <listitem><para>Thomas Gleixner<email>tglx@linutronix.de</email></para></listitem> - </orderedlist> - </para> - </chapter> -</book> diff --git a/Documentation/DocBook/networking.tmpl b/Documentation/DocBook/networking.tmpl deleted file mode 100644 index 29df25016c7c..000000000000 --- a/Documentation/DocBook/networking.tmpl +++ /dev/null @@ -1,111 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="LinuxNetworking"> - <bookinfo> - <title>Linux Networking and Network Devices APIs</title> - - <legalnotice> - <para> - This documentation is free software; you can redistribute - it and/or modify it under the terms of the GNU General Public - License as published by the Free Software Foundation; either - version 2 of the License, or (at your option) any later - version. - </para> - - <para> - This program is distributed in the hope that it will be - useful, but WITHOUT ANY WARRANTY; without even the implied - warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. - See the GNU General Public License for more details. - </para> - - <para> - You should have received a copy of the GNU General Public - License along with this program; if not, write to the Free - Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, - MA 02111-1307 USA - </para> - - <para> - For more details see the file COPYING in the source - distribution of Linux. - </para> - </legalnotice> - </bookinfo> - -<toc></toc> - - <chapter id="netcore"> - <title>Linux Networking</title> - <sect1><title>Networking Base Types</title> -!Iinclude/linux/net.h - </sect1> - <sect1><title>Socket Buffer Functions</title> -!Iinclude/linux/skbuff.h -!Iinclude/net/sock.h -!Enet/socket.c -!Enet/core/skbuff.c -!Enet/core/sock.c -!Enet/core/datagram.c -!Enet/core/stream.c - </sect1> - <sect1><title>Socket Filter</title> -!Enet/core/filter.c - </sect1> - <sect1><title>Generic Network Statistics</title> -!Iinclude/uapi/linux/gen_stats.h -!Enet/core/gen_stats.c -!Enet/core/gen_estimator.c - </sect1> - <sect1><title>SUN RPC subsystem</title> -<!-- The !D functionality is not perfect, garbage has to be protected by comments -!Dnet/sunrpc/sunrpc_syms.c ---> -!Enet/sunrpc/xdr.c -!Enet/sunrpc/svc_xprt.c -!Enet/sunrpc/xprt.c -!Enet/sunrpc/sched.c -!Enet/sunrpc/socklib.c -!Enet/sunrpc/stats.c -!Enet/sunrpc/rpc_pipe.c -!Enet/sunrpc/rpcb_clnt.c -!Enet/sunrpc/clnt.c - </sect1> - <sect1><title>WiMAX</title> -!Enet/wimax/op-msg.c -!Enet/wimax/op-reset.c -!Enet/wimax/op-rfkill.c -!Enet/wimax/stack.c -!Iinclude/net/wimax.h -!Iinclude/uapi/linux/wimax.h - </sect1> - </chapter> - - <chapter id="netdev"> - <title>Network device support</title> - <sect1><title>Driver Support</title> -!Enet/core/dev.c -!Enet/ethernet/eth.c -!Enet/sched/sch_generic.c -!Iinclude/linux/etherdevice.h -!Iinclude/linux/netdevice.h - </sect1> - <sect1><title>PHY Support</title> -!Edrivers/net/phy/phy.c -!Idrivers/net/phy/phy.c -!Edrivers/net/phy/phy_device.c -!Idrivers/net/phy/phy_device.c -!Edrivers/net/phy/mdio_bus.c -!Idrivers/net/phy/mdio_bus.c - </sect1> -<!-- FIXME: Removed for now since no structured comments in source - <sect1><title>Wireless</title> -X!Enet/core/wireless.c - </sect1> ---> - </chapter> - -</book> diff --git a/Documentation/DocBook/rapidio.tmpl b/Documentation/DocBook/rapidio.tmpl deleted file mode 100644 index ac3cca3399a1..000000000000 --- a/Documentation/DocBook/rapidio.tmpl +++ /dev/null @@ -1,155 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" [ - <!ENTITY rapidio SYSTEM "rapidio.xml"> - ]> - -<book id="RapidIO-Guide"> - <bookinfo> - <title>RapidIO Subsystem Guide</title> - - <authorgroup> - <author> - <firstname>Matt</firstname> - <surname>Porter</surname> - <affiliation> - <address> - <email>mporter@kernel.crashing.org</email> - <email>mporter@mvista.com</email> - </address> - </affiliation> - </author> - </authorgroup> - - <copyright> - <year>2005</year> - <holder>MontaVista Software, Inc.</holder> - </copyright> - - <legalnotice> - <para> - This documentation is free software; you can redistribute - it and/or modify it under the terms of the GNU General Public - License version 2 as published by the Free Software Foundation. - </para> - - <para> - This program is distributed in the hope that it will be - useful, but WITHOUT ANY WARRANTY; without even the implied - warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. - See the GNU General Public License for more details. - </para> - - <para> - You should have received a copy of the GNU General Public - License along with this program; if not, write to the Free - Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, - MA 02111-1307 USA - </para> - - <para> - For more details see the file COPYING in the source - distribution of Linux. - </para> - </legalnotice> - </bookinfo> - -<toc></toc> - - <chapter id="intro"> - <title>Introduction</title> - <para> - RapidIO is a high speed switched fabric interconnect with - features aimed at the embedded market. RapidIO provides - support for memory-mapped I/O as well as message-based - transactions over the switched fabric network. RapidIO has - a standardized discovery mechanism not unlike the PCI bus - standard that allows simple detection of devices in a - network. - </para> - <para> - This documentation is provided for developers intending - to support RapidIO on new architectures, write new drivers, - or to understand the subsystem internals. - </para> - </chapter> - - <chapter id="bugs"> - <title>Known Bugs and Limitations</title> - - <sect1 id="known_bugs"> - <title>Bugs</title> - <para>None. ;)</para> - </sect1> - <sect1 id="Limitations"> - <title>Limitations</title> - <para> - <orderedlist> - <listitem><para>Access/management of RapidIO memory regions is not supported</para></listitem> - <listitem><para>Multiple host enumeration is not supported</para></listitem> - </orderedlist> - </para> - </sect1> - </chapter> - - <chapter id="drivers"> - <title>RapidIO driver interface</title> - <para> - Drivers are provided a set of calls in order - to interface with the subsystem to gather info - on devices, request/map memory region resources, - and manage mailboxes/doorbells. - </para> - <sect1 id="Functions"> - <title>Functions</title> -!Iinclude/linux/rio_drv.h -!Edrivers/rapidio/rio-driver.c -!Edrivers/rapidio/rio.c - </sect1> - </chapter> - - <chapter id="internals"> - <title>Internals</title> - - <para> - This chapter contains the autogenerated documentation of the RapidIO - subsystem. - </para> - - <sect1 id="Structures"><title>Structures</title> -!Iinclude/linux/rio.h - </sect1> - <sect1 id="Enumeration_and_Discovery"><title>Enumeration and Discovery</title> -!Idrivers/rapidio/rio-scan.c - </sect1> - <sect1 id="Driver_functionality"><title>Driver functionality</title> -!Idrivers/rapidio/rio.c -!Idrivers/rapidio/rio-access.c - </sect1> - <sect1 id="Device_model_support"><title>Device model support</title> -!Idrivers/rapidio/rio-driver.c - </sect1> - <sect1 id="PPC32_support"><title>PPC32 support</title> -!Iarch/powerpc/sysdev/fsl_rio.c - </sect1> - </chapter> - - <chapter id="credits"> - <title>Credits</title> - <para> - The following people have contributed to the RapidIO - subsystem directly or indirectly: - <orderedlist> - <listitem><para>Matt Porter<email>mporter@kernel.crashing.org</email></para></listitem> - <listitem><para>Randy Vinson<email>rvinson@mvista.com</email></para></listitem> - <listitem><para>Dan Malek<email>dan@embeddedalley.com</email></para></listitem> - </orderedlist> - </para> - <para> - The following people have contributed to this document: - <orderedlist> - <listitem><para>Matt Porter<email>mporter@kernel.crashing.org</email></para></listitem> - </orderedlist> - </para> - </chapter> -</book> diff --git a/Documentation/DocBook/s390-drivers.tmpl b/Documentation/DocBook/s390-drivers.tmpl deleted file mode 100644 index 95bfc12e5439..000000000000 --- a/Documentation/DocBook/s390-drivers.tmpl +++ /dev/null @@ -1,161 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="s390drivers"> - <bookinfo> - <title>Writing s390 channel device drivers</title> - - <authorgroup> - <author> - <firstname>Cornelia</firstname> - <surname>Huck</surname> - <affiliation> - <address> - <email>cornelia.huck@de.ibm.com</email> - </address> - </affiliation> - </author> - </authorgroup> - - <copyright> - <year>2007</year> - <holder>IBM Corp.</holder> - </copyright> - - <legalnotice> - <para> - This documentation is free software; you can redistribute - it and/or modify it under the terms of the GNU General Public - License as published by the Free Software Foundation; either - version 2 of the License, or (at your option) any later - version. - </para> - - <para> - This program is distributed in the hope that it will be - useful, but WITHOUT ANY WARRANTY; without even the implied - warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. - See the GNU General Public License for more details. - </para> - - <para> - You should have received a copy of the GNU General Public - License along with this program; if not, write to the Free - Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, - MA 02111-1307 USA - </para> - - <para> - For more details see the file COPYING in the source - distribution of Linux. - </para> - </legalnotice> - </bookinfo> - -<toc></toc> - - <chapter id="intro"> - <title>Introduction</title> - <para> - This document describes the interfaces available for device drivers that - drive s390 based channel attached I/O devices. This includes interfaces for - interaction with the hardware and interfaces for interacting with the - common driver core. Those interfaces are provided by the s390 common I/O - layer. - </para> - <para> - The document assumes a familarity with the technical terms associated - with the s390 channel I/O architecture. For a description of this - architecture, please refer to the "z/Architecture: Principles of - Operation", IBM publication no. SA22-7832. - </para> - <para> - While most I/O devices on a s390 system are typically driven through the - channel I/O mechanism described here, there are various other methods - (like the diag interface). These are out of the scope of this document. - </para> - <para> - Some additional information can also be found in the kernel source - under Documentation/s390/driver-model.txt. - </para> - </chapter> - <chapter id="ccw"> - <title>The ccw bus</title> - <para> - The ccw bus typically contains the majority of devices available to - a s390 system. Named after the channel command word (ccw), the basic - command structure used to address its devices, the ccw bus contains - so-called channel attached devices. They are addressed via I/O - subchannels, visible on the css bus. A device driver for - channel-attached devices, however, will never interact with the - subchannel directly, but only via the I/O device on the ccw bus, - the ccw device. - </para> - <sect1 id="channelIO"> - <title>I/O functions for channel-attached devices</title> - <para> - Some hardware structures have been translated into C structures for use - by the common I/O layer and device drivers. For more information on - the hardware structures represented here, please consult the Principles - of Operation. - </para> -!Iarch/s390/include/asm/cio.h - </sect1> - <sect1 id="ccwdev"> - <title>ccw devices</title> - <para> - Devices that want to initiate channel I/O need to attach to the ccw bus. - Interaction with the driver core is done via the common I/O layer, which - provides the abstractions of ccw devices and ccw device drivers. - </para> - <para> - The functions that initiate or terminate channel I/O all act upon a - ccw device structure. Device drivers must not bypass those functions - or strange side effects may happen. - </para> -!Iarch/s390/include/asm/ccwdev.h -!Edrivers/s390/cio/device.c -!Edrivers/s390/cio/device_ops.c - </sect1> - <sect1 id="cmf"> - <title>The channel-measurement facility</title> - <para> - The channel-measurement facility provides a means to collect - measurement data which is made available by the channel subsystem - for each channel attached device. - </para> -!Iarch/s390/include/asm/cmb.h -!Edrivers/s390/cio/cmf.c - </sect1> - </chapter> - - <chapter id="ccwgroup"> - <title>The ccwgroup bus</title> - <para> - The ccwgroup bus only contains artificial devices, created by the user. - Many networking devices (e.g. qeth) are in fact composed of several - ccw devices (like read, write and data channel for qeth). The - ccwgroup bus provides a mechanism to create a meta-device which - contains those ccw devices as slave devices and can be associated - with the netdevice. - </para> - <sect1 id="ccwgroupdevices"> - <title>ccw group devices</title> -!Iarch/s390/include/asm/ccwgroup.h -!Edrivers/s390/cio/ccwgroup.c - </sect1> - </chapter> - - <chapter id="genericinterfaces"> - <title>Generic interfaces</title> - <para> - Some interfaces are available to other drivers that do not necessarily - have anything to do with the busses described above, but still are - indirectly using basic infrastructure in the common I/O layer. - One example is the support for adapter interrupts. - </para> -!Edrivers/s390/cio/airq.c - </chapter> - -</book> diff --git a/Documentation/DocBook/scsi.tmpl b/Documentation/DocBook/scsi.tmpl deleted file mode 100644 index 4b9b9b286cea..000000000000 --- a/Documentation/DocBook/scsi.tmpl +++ /dev/null @@ -1,409 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="scsimid"> - <bookinfo> - <title>SCSI Interfaces Guide</title> - - <authorgroup> - <author> - <firstname>James</firstname> - <surname>Bottomley</surname> - <affiliation> - <address> - <email>James.Bottomley@hansenpartnership.com</email> - </address> - </affiliation> - </author> - - <author> - <firstname>Rob</firstname> - <surname>Landley</surname> - <affiliation> - <address> - <email>rob@landley.net</email> - </address> - </affiliation> - </author> - - </authorgroup> - - <copyright> - <year>2007</year> - <holder>Linux Foundation</holder> - </copyright> - - <legalnotice> - <para> - This documentation is free software; you can redistribute - it and/or modify it under the terms of the GNU General Public - License version 2. - </para> - - <para> - This program is distributed in the hope that it will be - useful, but WITHOUT ANY WARRANTY; without even the implied - warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. - For more details see the file COPYING in the source - distribution of Linux. - </para> - </legalnotice> - </bookinfo> - - <toc></toc> - - <chapter id="intro"> - <title>Introduction</title> - <sect1 id="protocol_vs_bus"> - <title>Protocol vs bus</title> - <para> - Once upon a time, the Small Computer Systems Interface defined both - a parallel I/O bus and a data protocol to connect a wide variety of - peripherals (disk drives, tape drives, modems, printers, scanners, - optical drives, test equipment, and medical devices) to a host - computer. - </para> - <para> - Although the old parallel (fast/wide/ultra) SCSI bus has largely - fallen out of use, the SCSI command set is more widely used than ever - to communicate with devices over a number of different busses. - </para> - <para> - The <ulink url='http://www.t10.org/scsi-3.htm'>SCSI protocol</ulink> - is a big-endian peer-to-peer packet based protocol. SCSI commands - are 6, 10, 12, or 16 bytes long, often followed by an associated data - payload. - </para> - <para> - SCSI commands can be transported over just about any kind of bus, and - are the default protocol for storage devices attached to USB, SATA, - SAS, Fibre Channel, FireWire, and ATAPI devices. SCSI packets are - also commonly exchanged over Infiniband, - <ulink url='http://i2o.shadowconnect.com/faq.php'>I20</ulink>, TCP/IP - (<ulink url='https://en.wikipedia.org/wiki/ISCSI'>iSCSI</ulink>), even - <ulink url='http://cyberelk.net/tim/parport/parscsi.html'>Parallel - ports</ulink>. - </para> - </sect1> - <sect1 id="subsystem_design"> - <title>Design of the Linux SCSI subsystem</title> - <para> - The SCSI subsystem uses a three layer design, with upper, mid, and low - layers. Every operation involving the SCSI subsystem (such as reading - a sector from a disk) uses one driver at each of the 3 levels: one - upper layer driver, one lower layer driver, and the SCSI midlayer. - </para> - <para> - The SCSI upper layer provides the interface between userspace and the - kernel, in the form of block and char device nodes for I/O and - ioctl(). The SCSI lower layer contains drivers for specific hardware - devices. - </para> - <para> - In between is the SCSI mid-layer, analogous to a network routing - layer such as the IPv4 stack. The SCSI mid-layer routes a packet - based data protocol between the upper layer's /dev nodes and the - corresponding devices in the lower layer. It manages command queues, - provides error handling and power management functions, and responds - to ioctl() requests. - </para> - </sect1> - </chapter> - - <chapter id="upper_layer"> - <title>SCSI upper layer</title> - <para> - The upper layer supports the user-kernel interface by providing - device nodes. - </para> - <sect1 id="sd"> - <title>sd (SCSI Disk)</title> - <para>sd (sd_mod.o)</para> -<!-- !Idrivers/scsi/sd.c --> - </sect1> - <sect1 id="sr"> - <title>sr (SCSI CD-ROM)</title> - <para>sr (sr_mod.o)</para> - </sect1> - <sect1 id="st"> - <title>st (SCSI Tape)</title> - <para>st (st.o)</para> - </sect1> - <sect1 id="sg"> - <title>sg (SCSI Generic)</title> - <para>sg (sg.o)</para> - </sect1> - <sect1 id="ch"> - <title>ch (SCSI Media Changer)</title> - <para>ch (ch.c)</para> - </sect1> - </chapter> - - <chapter id="mid_layer"> - <title>SCSI mid layer</title> - - <sect1 id="midlayer_implementation"> - <title>SCSI midlayer implementation</title> - <sect2 id="scsi_device.h"> - <title>include/scsi/scsi_device.h</title> - <para> - </para> -!Iinclude/scsi/scsi_device.h - </sect2> - - <sect2 id="scsi.c"> - <title>drivers/scsi/scsi.c</title> - <para>Main file for the SCSI midlayer.</para> -!Edrivers/scsi/scsi.c - </sect2> - <sect2 id="scsicam.c"> - <title>drivers/scsi/scsicam.c</title> - <para> - <ulink url='http://www.t10.org/ftp/t10/drafts/cam/cam-r12b.pdf'>SCSI - Common Access Method</ulink> support functions, for use with - HDIO_GETGEO, etc. - </para> -!Edrivers/scsi/scsicam.c - </sect2> - <sect2 id="scsi_error.c"> - <title>drivers/scsi/scsi_error.c</title> - <para>Common SCSI error/timeout handling routines.</para> -!Edrivers/scsi/scsi_error.c - </sect2> - <sect2 id="scsi_devinfo.c"> - <title>drivers/scsi/scsi_devinfo.c</title> - <para> - Manage scsi_dev_info_list, which tracks blacklisted and whitelisted - devices. - </para> -!Idrivers/scsi/scsi_devinfo.c - </sect2> - <sect2 id="scsi_ioctl.c"> - <title>drivers/scsi/scsi_ioctl.c</title> - <para> - Handle ioctl() calls for SCSI devices. - </para> -!Edrivers/scsi/scsi_ioctl.c - </sect2> - <sect2 id="scsi_lib.c"> - <title>drivers/scsi/scsi_lib.c</title> - <para> - SCSI queuing library. - </para> -!Edrivers/scsi/scsi_lib.c - </sect2> - <sect2 id="scsi_lib_dma.c"> - <title>drivers/scsi/scsi_lib_dma.c</title> - <para> - SCSI library functions depending on DMA - (map and unmap scatter-gather lists). - </para> -!Edrivers/scsi/scsi_lib_dma.c - </sect2> - <sect2 id="scsi_module.c"> - <title>drivers/scsi/scsi_module.c</title> - <para> - The file drivers/scsi/scsi_module.c contains legacy support for - old-style host templates. It should never be used by any new driver. - </para> - </sect2> - <sect2 id="scsi_proc.c"> - <title>drivers/scsi/scsi_proc.c</title> - <para> - The functions in this file provide an interface between - the PROC file system and the SCSI device drivers - It is mainly used for debugging, statistics and to pass - information directly to the lowlevel driver. - - I.E. plumbing to manage /proc/scsi/* - </para> -!Idrivers/scsi/scsi_proc.c - </sect2> - <sect2 id="scsi_netlink.c"> - <title>drivers/scsi/scsi_netlink.c</title> - <para> - Infrastructure to provide async events from transports to userspace - via netlink, using a single NETLINK_SCSITRANSPORT protocol for all - transports. - - See <ulink url='http://marc.info/?l=linux-scsi&m=115507374832500&w=2'>the - original patch submission</ulink> for more details. - </para> -!Idrivers/scsi/scsi_netlink.c - </sect2> - <sect2 id="scsi_scan.c"> - <title>drivers/scsi/scsi_scan.c</title> - <para> - Scan a host to determine which (if any) devices are attached. - - The general scanning/probing algorithm is as follows, exceptions are - made to it depending on device specific flags, compilation options, - and global variable (boot or module load time) settings. - - A specific LUN is scanned via an INQUIRY command; if the LUN has a - device attached, a scsi_device is allocated and setup for it. - - For every id of every channel on the given host, start by scanning - LUN 0. Skip hosts that don't respond at all to a scan of LUN 0. - Otherwise, if LUN 0 has a device attached, allocate and setup a - scsi_device for it. If target is SCSI-3 or up, issue a REPORT LUN, - and scan all of the LUNs returned by the REPORT LUN; else, - sequentially scan LUNs up until some maximum is reached, or a LUN is - seen that cannot have a device attached to it. - </para> -!Idrivers/scsi/scsi_scan.c - </sect2> - <sect2 id="scsi_sysctl.c"> - <title>drivers/scsi/scsi_sysctl.c</title> - <para> - Set up the sysctl entry: "/dev/scsi/logging_level" - (DEV_SCSI_LOGGING_LEVEL) which sets/returns scsi_logging_level. - </para> - </sect2> - <sect2 id="scsi_sysfs.c"> - <title>drivers/scsi/scsi_sysfs.c</title> - <para> - SCSI sysfs interface routines. - </para> -!Edrivers/scsi/scsi_sysfs.c - </sect2> - <sect2 id="hosts.c"> - <title>drivers/scsi/hosts.c</title> - <para> - mid to lowlevel SCSI driver interface - </para> -!Edrivers/scsi/hosts.c - </sect2> - <sect2 id="constants.c"> - <title>drivers/scsi/constants.c</title> - <para> - mid to lowlevel SCSI driver interface - </para> -!Edrivers/scsi/constants.c - </sect2> - </sect1> - - <sect1 id="Transport_classes"> - <title>Transport classes</title> - <para> - Transport classes are service libraries for drivers in the SCSI - lower layer, which expose transport attributes in sysfs. - </para> - <sect2 id="Fibre_Channel_transport"> - <title>Fibre Channel transport</title> - <para> - The file drivers/scsi/scsi_transport_fc.c defines transport attributes - for Fibre Channel. - </para> -!Edrivers/scsi/scsi_transport_fc.c - </sect2> - <sect2 id="iSCSI_transport"> - <title>iSCSI transport class</title> - <para> - The file drivers/scsi/scsi_transport_iscsi.c defines transport - attributes for the iSCSI class, which sends SCSI packets over TCP/IP - connections. - </para> -!Edrivers/scsi/scsi_transport_iscsi.c - </sect2> - <sect2 id="SAS_transport"> - <title>Serial Attached SCSI (SAS) transport class</title> - <para> - The file drivers/scsi/scsi_transport_sas.c defines transport - attributes for Serial Attached SCSI, a variant of SATA aimed at - large high-end systems. - </para> - <para> - The SAS transport class contains common code to deal with SAS HBAs, - an aproximated representation of SAS topologies in the driver model, - and various sysfs attributes to expose these topologies and management - interfaces to userspace. - </para> - <para> - In addition to the basic SCSI core objects this transport class - introduces two additional intermediate objects: The SAS PHY - as represented by struct sas_phy defines an "outgoing" PHY on - a SAS HBA or Expander, and the SAS remote PHY represented by - struct sas_rphy defines an "incoming" PHY on a SAS Expander or - end device. Note that this is purely a software concept, the - underlying hardware for a PHY and a remote PHY is the exactly - the same. - </para> - <para> - There is no concept of a SAS port in this code, users can see - what PHYs form a wide port based on the port_identifier attribute, - which is the same for all PHYs in a port. - </para> -!Edrivers/scsi/scsi_transport_sas.c - </sect2> - <sect2 id="SATA_transport"> - <title>SATA transport class</title> - <para> - The SATA transport is handled by libata, which has its own book of - documentation in this directory. - </para> - </sect2> - <sect2 id="SPI_transport"> - <title>Parallel SCSI (SPI) transport class</title> - <para> - The file drivers/scsi/scsi_transport_spi.c defines transport - attributes for traditional (fast/wide/ultra) SCSI busses. - </para> -!Edrivers/scsi/scsi_transport_spi.c - </sect2> - <sect2 id="SRP_transport"> - <title>SCSI RDMA (SRP) transport class</title> - <para> - The file drivers/scsi/scsi_transport_srp.c defines transport - attributes for SCSI over Remote Direct Memory Access. - </para> -!Edrivers/scsi/scsi_transport_srp.c - </sect2> - </sect1> - - </chapter> - - <chapter id="lower_layer"> - <title>SCSI lower layer</title> - <sect1 id="hba_drivers"> - <title>Host Bus Adapter transport types</title> - <para> - Many modern device controllers use the SCSI command set as a protocol to - communicate with their devices through many different types of physical - connections. - </para> - <para> - In SCSI language a bus capable of carrying SCSI commands is - called a "transport", and a controller connecting to such a bus is - called a "host bus adapter" (HBA). - </para> - <sect2 id="scsi_debug.c"> - <title>Debug transport</title> - <para> - The file drivers/scsi/scsi_debug.c simulates a host adapter with a - variable number of disks (or disk like devices) attached, sharing a - common amount of RAM. Does a lot of checking to make sure that we are - not getting blocks mixed up, and panics the kernel if anything out of - the ordinary is seen. - </para> - <para> - To be more realistic, the simulated devices have the transport - attributes of SAS disks. - </para> - <para> - For documentation see - <ulink url='http://sg.danny.cz/sg/sdebug26.html'>http://sg.danny.cz/sg/sdebug26.html</ulink> - </para> -<!-- !Edrivers/scsi/scsi_debug.c --> - </sect2> - <sect2 id="todo"> - <title>todo</title> - <para>Parallel (fast/wide/ultra) SCSI, USB, SATA, - SAS, Fibre Channel, FireWire, ATAPI devices, Infiniband, - I20, iSCSI, Parallel ports, netlink... - </para> - </sect2> - </sect1> - </chapter> -</book> diff --git a/Documentation/DocBook/sh.tmpl b/Documentation/DocBook/sh.tmpl deleted file mode 100644 index 4a38f604fa66..000000000000 --- a/Documentation/DocBook/sh.tmpl +++ /dev/null @@ -1,105 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="sh-drivers"> - <bookinfo> - <title>SuperH Interfaces Guide</title> - - <authorgroup> - <author> - <firstname>Paul</firstname> - <surname>Mundt</surname> - <affiliation> - <address> - <email>lethal@linux-sh.org</email> - </address> - </affiliation> - </author> - </authorgroup> - - <copyright> - <year>2008-2010</year> - <holder>Paul Mundt</holder> - </copyright> - <copyright> - <year>2008-2010</year> - <holder>Renesas Technology Corp.</holder> - </copyright> - <copyright> - <year>2010</year> - <holder>Renesas Electronics Corp.</holder> - </copyright> - - <legalnotice> - <para> - This documentation is free software; you can redistribute - it and/or modify it under the terms of the GNU General Public - License version 2 as published by the Free Software Foundation. - </para> - - <para> - This program is distributed in the hope that it will be - useful, but WITHOUT ANY WARRANTY; without even the implied - warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. - See the GNU General Public License for more details. - </para> - - <para> - You should have received a copy of the GNU General Public - License along with this program; if not, write to the Free - Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, - MA 02111-1307 USA - </para> - - <para> - For more details see the file COPYING in the source - distribution of Linux. - </para> - </legalnotice> - </bookinfo> - -<toc></toc> - - <chapter id="mm"> - <title>Memory Management</title> - <sect1 id="sh4"> - <title>SH-4</title> - <sect2 id="sq"> - <title>Store Queue API</title> -!Earch/sh/kernel/cpu/sh4/sq.c - </sect2> - </sect1> - <sect1 id="sh5"> - <title>SH-5</title> - <sect2 id="tlb"> - <title>TLB Interfaces</title> -!Iarch/sh/mm/tlb-sh5.c -!Iarch/sh/include/asm/tlb_64.h - </sect2> - </sect1> - </chapter> - <chapter id="mach"> - <title>Machine Specific Interfaces</title> - <sect1 id="dreamcast"> - <title>mach-dreamcast</title> -!Iarch/sh/boards/mach-dreamcast/rtc.c - </sect1> - <sect1 id="x3proto"> - <title>mach-x3proto</title> -!Earch/sh/boards/mach-x3proto/ilsel.c - </sect1> - </chapter> - <chapter id="busses"> - <title>Busses</title> - <sect1 id="superhyway"> - <title>SuperHyway</title> -!Edrivers/sh/superhyway/superhyway.c - </sect1> - - <sect1 id="maple"> - <title>Maple</title> -!Edrivers/sh/maple/maple.c - </sect1> - </chapter> -</book> diff --git a/Documentation/DocBook/stylesheet.xsl b/Documentation/DocBook/stylesheet.xsl deleted file mode 100644 index 3bf4ecf3d760..000000000000 --- a/Documentation/DocBook/stylesheet.xsl +++ /dev/null @@ -1,11 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<stylesheet xmlns="http://www.w3.org/1999/XSL/Transform" version="1.0"> -<param name="chunk.quietly">1</param> -<param name="funcsynopsis.style">ansi</param> -<param name="funcsynopsis.tabular.threshold">80</param> -<param name="callout.graphics">0</param> -<!-- <param name="paper.type">A4</param> --> -<param name="generate.consistent.ids">1</param> -<param name="generate.section.toc.level">2</param> -<param name="use.id.as.filename">1</param> -</stylesheet> diff --git a/Documentation/DocBook/w1.tmpl b/Documentation/DocBook/w1.tmpl deleted file mode 100644 index b0228d4c81bb..000000000000 --- a/Documentation/DocBook/w1.tmpl +++ /dev/null @@ -1,101 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="w1id"> - <bookinfo> - <title>W1: Dallas' 1-wire bus</title> - - <authorgroup> - <author> - <firstname>David</firstname> - <surname>Fries</surname> - <affiliation> - <address> - <email>David@Fries.net</email> - </address> - </affiliation> - </author> - - </authorgroup> - - <copyright> - <year>2013</year> - <!-- - <holder></holder> - --> - </copyright> - - <legalnotice> - <para> - This documentation is free software; you can redistribute - it and/or modify it under the terms of the GNU General Public - License version 2. - </para> - - <para> - This program is distributed in the hope that it will be - useful, but WITHOUT ANY WARRANTY; without even the implied - warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. - For more details see the file COPYING in the source - distribution of Linux. - </para> - </legalnotice> - </bookinfo> - - <toc></toc> - - <chapter id="w1_internal"> - <title>W1 API internal to the kernel</title> - - <sect1 id="w1_internal_api"> - <title>W1 API internal to the kernel</title> - <sect2 id="w1.h"> - <title>drivers/w1/w1.h</title> - <para>W1 core functions.</para> -!Idrivers/w1/w1.h - </sect2> - - <sect2 id="w1.c"> - <title>drivers/w1/w1.c</title> - <para>W1 core functions.</para> -!Idrivers/w1/w1.c - </sect2> - - <sect2 id="w1_family.h"> - <title>drivers/w1/w1_family.h</title> - <para>Allows registering device family operations.</para> -!Idrivers/w1/w1_family.h - </sect2> - - <sect2 id="w1_family.c"> - <title>drivers/w1/w1_family.c</title> - <para>Allows registering device family operations.</para> -!Edrivers/w1/w1_family.c - </sect2> - - <sect2 id="w1_int.c"> - <title>drivers/w1/w1_int.c</title> - <para>W1 internal initialization for master devices.</para> -!Edrivers/w1/w1_int.c - </sect2> - - <sect2 id="w1_netlink.h"> - <title>drivers/w1/w1_netlink.h</title> - <para>W1 external netlink API structures and commands.</para> -!Idrivers/w1/w1_netlink.h - </sect2> - - <sect2 id="w1_io.c"> - <title>drivers/w1/w1_io.c</title> - <para>W1 input/output.</para> -!Edrivers/w1/w1_io.c -!Idrivers/w1/w1_io.c - </sect2> - - </sect1> - - - </chapter> - -</book> diff --git a/Documentation/DocBook/z8530book.tmpl b/Documentation/DocBook/z8530book.tmpl deleted file mode 100644 index 6f3883be877e..000000000000 --- a/Documentation/DocBook/z8530book.tmpl +++ /dev/null @@ -1,371 +0,0 @@ -<?xml version="1.0" encoding="UTF-8"?> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> - -<book id="Z85230Guide"> - <bookinfo> - <title>Z8530 Programming Guide</title> - - <authorgroup> - <author> - <firstname>Alan</firstname> - <surname>Cox</surname> - <affiliation> - <address> - <email>alan@lxorguk.ukuu.org.uk</email> - </address> - </affiliation> - </author> - </authorgroup> - - <copyright> - <year>2000</year> - <holder>Alan Cox</holder> - </copyright> - - <legalnotice> - <para> - This documentation is free software; you can redistribute - it and/or modify it under the terms of the GNU General Public - License as published by the Free Software Foundation; either - version 2 of the License, or (at your option) any later - version. - </para> - - <para> - This program is distributed in the hope that it will be - useful, but WITHOUT ANY WARRANTY; without even the implied - warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. - See the GNU General Public License for more details. - </para> - - <para> - You should have received a copy of the GNU General Public - License along with this program; if not, write to the Free - Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, - MA 02111-1307 USA - </para> - - <para> - For more details see the file COPYING in the source - distribution of Linux. - </para> - </legalnotice> - </bookinfo> - -<toc></toc> - - <chapter id="intro"> - <title>Introduction</title> - <para> - The Z85x30 family synchronous/asynchronous controller chips are - used on a large number of cheap network interface cards. The - kernel provides a core interface layer that is designed to make - it easy to provide WAN services using this chip. - </para> - <para> - The current driver only support synchronous operation. Merging the - asynchronous driver support into this code to allow any Z85x30 - device to be used as both a tty interface and as a synchronous - controller is a project for Linux post the 2.4 release - </para> - </chapter> - - <chapter id="Driver_Modes"> - <title>Driver Modes</title> - <para> - The Z85230 driver layer can drive Z8530, Z85C30 and Z85230 devices - in three different modes. Each mode can be applied to an individual - channel on the chip (each chip has two channels). - </para> - <para> - The PIO synchronous mode supports the most common Z8530 wiring. Here - the chip is interface to the I/O and interrupt facilities of the - host machine but not to the DMA subsystem. When running PIO the - Z8530 has extremely tight timing requirements. Doing high speeds, - even with a Z85230 will be tricky. Typically you should expect to - achieve at best 9600 baud with a Z8C530 and 64Kbits with a Z85230. - </para> - <para> - The DMA mode supports the chip when it is configured to use dual DMA - channels on an ISA bus. The better cards tend to support this mode - of operation for a single channel. With DMA running the Z85230 tops - out when it starts to hit ISA DMA constraints at about 512Kbits. It - is worth noting here that many PC machines hang or crash when the - chip is driven fast enough to hold the ISA bus solid. - </para> - <para> - Transmit DMA mode uses a single DMA channel. The DMA channel is used - for transmission as the transmit FIFO is smaller than the receive - FIFO. it gives better performance than pure PIO mode but is nowhere - near as ideal as pure DMA mode. - </para> - </chapter> - - <chapter id="Using_the_Z85230_driver"> - <title>Using the Z85230 driver</title> - <para> - The Z85230 driver provides the back end interface to your board. To - configure a Z8530 interface you need to detect the board and to - identify its ports and interrupt resources. It is also your problem - to verify the resources are available. - </para> - <para> - Having identified the chip you need to fill in a struct z8530_dev, - which describes each chip. This object must exist until you finally - shutdown the board. Firstly zero the active field. This ensures - nothing goes off without you intending it. The irq field should - be set to the interrupt number of the chip. (Each chip has a single - interrupt source rather than each channel). You are responsible - for allocating the interrupt line. The interrupt handler should be - set to <function>z8530_interrupt</function>. The device id should - be set to the z8530_dev structure pointer. Whether the interrupt can - be shared or not is board dependent, and up to you to initialise. - </para> - <para> - The structure holds two channel structures. - Initialise chanA.ctrlio and chanA.dataio with the address of the - control and data ports. You can or this with Z8530_PORT_SLEEP to - indicate your interface needs the 5uS delay for chip settling done - in software. The PORT_SLEEP option is architecture specific. Other - flags may become available on future platforms, eg for MMIO. - Initialise the chanA.irqs to &z8530_nop to start the chip up - as disabled and discarding interrupt events. This ensures that - stray interrupts will be mopped up and not hang the bus. Set - chanA.dev to point to the device structure itself. The - private and name field you may use as you wish. The private field - is unused by the Z85230 layer. The name is used for error reporting - and it may thus make sense to make it match the network name. - </para> - <para> - Repeat the same operation with the B channel if your chip has - both channels wired to something useful. This isn't always the - case. If it is not wired then the I/O values do not matter, but - you must initialise chanB.dev. - </para> - <para> - If your board has DMA facilities then initialise the txdma and - rxdma fields for the relevant channels. You must also allocate the - ISA DMA channels and do any necessary board level initialisation - to configure them. The low level driver will do the Z8530 and - DMA controller programming but not board specific magic. - </para> - <para> - Having initialised the device you can then call - <function>z8530_init</function>. This will probe the chip and - reset it into a known state. An identification sequence is then - run to identify the chip type. If the checks fail to pass the - function returns a non zero error code. Typically this indicates - that the port given is not valid. After this call the - type field of the z8530_dev structure is initialised to either - Z8530, Z85C30 or Z85230 according to the chip found. - </para> - <para> - Once you have called z8530_init you can also make use of the utility - function <function>z8530_describe</function>. This provides a - consistent reporting format for the Z8530 devices, and allows all - the drivers to provide consistent reporting. - </para> - </chapter> - - <chapter id="Attaching_Network_Interfaces"> - <title>Attaching Network Interfaces</title> - <para> - If you wish to use the network interface facilities of the driver, - then you need to attach a network device to each channel that is - present and in use. In addition to use the generic HDLC - you need to follow some additional plumbing rules. They may seem - complex but a look at the example hostess_sv11 driver should - reassure you. - </para> - <para> - The network device used for each channel should be pointed to by - the netdevice field of each channel. The hdlc-> priv field of the - network device points to your private data - you will need to be - able to find your private data from this. - </para> - <para> - The way most drivers approach this particular problem is to - create a structure holding the Z8530 device definition and - put that into the private field of the network device. The - network device fields of the channels then point back to the - network devices. - </para> - <para> - If you wish to use the generic HDLC then you need to register - the HDLC device. - </para> - <para> - Before you register your network device you will also need to - provide suitable handlers for most of the network device callbacks. - See the network device documentation for more details on this. - </para> - </chapter> - - <chapter id="Configuring_And_Activating_The_Port"> - <title>Configuring And Activating The Port</title> - <para> - The Z85230 driver provides helper functions and tables to load the - port registers on the Z8530 chips. When programming the register - settings for a channel be aware that the documentation recommends - initialisation orders. Strange things happen when these are not - followed. - </para> - <para> - <function>z8530_channel_load</function> takes an array of - pairs of initialisation values in an array of u8 type. The first - value is the Z8530 register number. Add 16 to indicate the alternate - register bank on the later chips. The array is terminated by a 255. - </para> - <para> - The driver provides a pair of public tables. The - z8530_hdlc_kilostream table is for the UK 'Kilostream' service and - also happens to cover most other end host configurations. The - z8530_hdlc_kilostream_85230 table is the same configuration using - the enhancements of the 85230 chip. The configuration loaded is - standard NRZ encoded synchronous data with HDLC bitstuffing. All - of the timing is taken from the other end of the link. - </para> - <para> - When writing your own tables be aware that the driver internally - tracks register values. It may need to reload values. You should - therefore be sure to set registers 1-7, 9-11, 14 and 15 in all - configurations. Where the register settings depend on DMA selection - the driver will update the bits itself when you open or close. - Loading a new table with the interface open is not recommended. - </para> - <para> - There are three standard configurations supported by the core - code. In PIO mode the interface is programmed up to use - interrupt driven PIO. This places high demands on the host processor - to avoid latency. The driver is written to take account of latency - issues but it cannot avoid latencies caused by other drivers, - notably IDE in PIO mode. Because the drivers allocate buffers you - must also prevent MTU changes while the port is open. - </para> - <para> - Once the port is open it will call the rx_function of each channel - whenever a completed packet arrived. This is invoked from - interrupt context and passes you the channel and a network - buffer (struct sk_buff) holding the data. The data includes - the CRC bytes so most users will want to trim the last two - bytes before processing the data. This function is very timing - critical. When you wish to simply discard data the support - code provides the function <function>z8530_null_rx</function> - to discard the data. - </para> - <para> - To active PIO mode sending and receiving the <function> - z8530_sync_open</function> is called. This expects to be passed - the network device and the channel. Typically this is called from - your network device open callback. On a failure a non zero error - status is returned. The <function>z8530_sync_close</function> - function shuts down a PIO channel. This must be done before the - channel is opened again and before the driver shuts down - and unloads. - </para> - <para> - The ideal mode of operation is dual channel DMA mode. Here the - kernel driver will configure the board for DMA in both directions. - The driver also handles ISA DMA issues such as controller - programming and the memory range limit for you. This mode is - activated by calling the <function>z8530_sync_dma_open</function> - function. On failure a non zero error value is returned. - Once this mode is activated it can be shut down by calling the - <function>z8530_sync_dma_close</function>. You must call the close - function matching the open mode you used. - </para> - <para> - The final supported mode uses a single DMA channel to drive the - transmit side. As the Z85C30 has a larger FIFO on the receive - channel this tends to increase the maximum speed a little. - This is activated by calling the <function>z8530_sync_txdma_open - </function>. This returns a non zero error code on failure. The - <function>z8530_sync_txdma_close</function> function closes down - the Z8530 interface from this mode. - </para> - </chapter> - - <chapter id="Network_Layer_Functions"> - <title>Network Layer Functions</title> - <para> - The Z8530 layer provides functions to queue packets for - transmission. The driver internally buffers the frame currently - being transmitted and one further frame (in order to keep back - to back transmission running). Any further buffering is up to - the caller. - </para> - <para> - The function <function>z8530_queue_xmit</function> takes a network - buffer in sk_buff format and queues it for transmission. The - caller must provide the entire packet with the exception of the - bitstuffing and CRC. This is normally done by the caller via - the generic HDLC interface layer. It returns 0 if the buffer has been - queued and non zero values for queue full. If the function accepts - the buffer it becomes property of the Z8530 layer and the caller - should not free it. - </para> - <para> - The function <function>z8530_get_stats</function> returns a pointer - to an internally maintained per interface statistics block. This - provides most of the interface code needed to implement the network - layer get_stats callback. - </para> - </chapter> - - <chapter id="Porting_The_Z8530_Driver"> - <title>Porting The Z8530 Driver</title> - <para> - The Z8530 driver is written to be portable. In DMA mode it makes - assumptions about the use of ISA DMA. These are probably warranted - in most cases as the Z85230 in particular was designed to glue to PC - type machines. The PIO mode makes no real assumptions. - </para> - <para> - Should you need to retarget the Z8530 driver to another architecture - the only code that should need changing are the port I/O functions. - At the moment these assume PC I/O port accesses. This may not be - appropriate for all platforms. Replacing - <function>z8530_read_port</function> and <function>z8530_write_port - </function> is intended to be all that is required to port this - driver layer. - </para> - </chapter> - - <chapter id="bugs"> - <title>Known Bugs And Assumptions</title> - <para> - <variablelist> - <varlistentry><term>Interrupt Locking</term> - <listitem> - <para> - The locking in the driver is done via the global cli/sti lock. This - makes for relatively poor SMP performance. Switching this to use a - per device spin lock would probably materially improve performance. - </para> - </listitem></varlistentry> - - <varlistentry><term>Occasional Failures</term> - <listitem> - <para> - We have reports of occasional failures when run for very long - periods of time and the driver starts to receive junk frames. At - the moment the cause of this is not clear. - </para> - </listitem></varlistentry> - </variablelist> - - </para> - </chapter> - - <chapter id="pubfunctions"> - <title>Public Functions Provided</title> -!Edrivers/net/wan/z85230.c - </chapter> - - <chapter id="intfunctions"> - <title>Internal Functions</title> -!Idrivers/net/wan/z85230.c - </chapter> - -</book> diff --git a/Documentation/IRQ-domain.txt b/Documentation/IRQ-domain.txt index 82001a25a14b..1f246eb25ca5 100644 --- a/Documentation/IRQ-domain.txt +++ b/Documentation/IRQ-domain.txt @@ -231,5 +231,42 @@ needs to: 4) No need to implement irq_domain_ops.map and irq_domain_ops.unmap, they are unused with hierarchy irq_domain. -Hierarchy irq_domain may also be used to support other architectures, -such as ARM, ARM64 etc. +Hierarchy irq_domain is in no way x86 specific, and is heavily used to +support other architectures, such as ARM, ARM64 etc. + +=== Debugging === + +If you switch on CONFIG_IRQ_DOMAIN_DEBUG (which depends on +CONFIG_IRQ_DOMAIN and CONFIG_DEBUG_FS), you will find a new file in +your debugfs mount point, called irq_domain_mapping. This file +contains a live snapshot of all the IRQ domains in the system: + + name mapped linear-max direct-max devtree-node + pl061 8 8 0 /smb/gpio@e0080000 + pl061 8 8 0 /smb/gpio@e1050000 + pMSI 0 0 0 /interrupt-controller@e1101000/v2m@e0080000 + MSI 37 0 0 /interrupt-controller@e1101000/v2m@e0080000 + GICv2m 37 0 0 /interrupt-controller@e1101000/v2m@e0080000 + GICv2 448 448 0 /interrupt-controller@e1101000 + +it also iterates over the interrupts to display their mapping in the +domains, and makes the domain stacking visible: + + +irq hwirq chip name chip data active type domain + 1 0x00019 GICv2 0xffff00000916bfd8 * LINEAR GICv2 + 2 0x0001d GICv2 0xffff00000916bfd8 LINEAR GICv2 + 3 0x0001e GICv2 0xffff00000916bfd8 * LINEAR GICv2 + 4 0x0001b GICv2 0xffff00000916bfd8 * LINEAR GICv2 + 5 0x0001a GICv2 0xffff00000916bfd8 LINEAR GICv2 +[...] + 96 0x81808 MSI 0x (null) RADIX MSI + 96+ 0x00063 GICv2m 0xffff8003ee116980 RADIX GICv2m + 96+ 0x00063 GICv2 0xffff00000916bfd8 LINEAR GICv2 + 97 0x08800 MSI 0x (null) * RADIX MSI + 97+ 0x00064 GICv2m 0xffff8003ee116980 * RADIX GICv2m + 97+ 0x00064 GICv2 0xffff00000916bfd8 * LINEAR GICv2 + +Here, interrupts 1-5 are only using a single domain, while 96 and 97 +are build out of a stack of three domain, each level performing a +particular function. diff --git a/Documentation/Makefile b/Documentation/Makefile index c2a469112c37..a42320385df3 100644 --- a/Documentation/Makefile +++ b/Documentation/Makefile @@ -1 +1,126 @@ +# -*- makefile -*- +# Makefile for Sphinx documentation +# + subdir-y := + +# You can set these variables from the command line. +SPHINXBUILD = sphinx-build +SPHINXOPTS = +SPHINXDIRS = . +_SPHINXDIRS = $(patsubst $(srctree)/Documentation/%/conf.py,%,$(wildcard $(srctree)/Documentation/*/conf.py)) +SPHINX_CONF = conf.py +PAPER = +BUILDDIR = $(obj)/output +PDFLATEX = xelatex +LATEXOPTS = -interaction=batchmode + +# User-friendly check for sphinx-build +HAVE_SPHINX := $(shell if which $(SPHINXBUILD) >/dev/null 2>&1; then echo 1; else echo 0; fi) + +ifeq ($(HAVE_SPHINX),0) + +.DEFAULT: + $(warning The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed and in PATH, or set the SPHINXBUILD make variable to point to the full path of the '$(SPHINXBUILD)' executable.) + @echo " SKIP Sphinx $@ target." + +else # HAVE_SPHINX + +# User-friendly check for pdflatex +HAVE_PDFLATEX := $(shell if which $(PDFLATEX) >/dev/null 2>&1; then echo 1; else echo 0; fi) + +# Internal variables. +PAPEROPT_a4 = -D latex_paper_size=a4 +PAPEROPT_letter = -D latex_paper_size=letter +KERNELDOC = $(srctree)/scripts/kernel-doc +KERNELDOC_CONF = -D kerneldoc_srctree=$(srctree) -D kerneldoc_bin=$(KERNELDOC) +ALLSPHINXOPTS = $(KERNELDOC_CONF) $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) +# the i18n builder cannot share the environment and doctrees with the others +I18NSPHINXOPTS = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) . + +# commands; the 'cmd' from scripts/Kbuild.include is not *loopable* +loop_cmd = $(echo-cmd) $(cmd_$(1)) || exit; + +# $2 sphinx builder e.g. "html" +# $3 name of the build subfolder / e.g. "media", used as: +# * dest folder relative to $(BUILDDIR) and +# * cache folder relative to $(BUILDDIR)/.doctrees +# $4 dest subfolder e.g. "man" for man pages at media/man +# $5 reST source folder relative to $(srctree)/$(src), +# e.g. "media" for the linux-tv book-set at ./Documentation/media + +quiet_cmd_sphinx = SPHINX $@ --> file://$(abspath $(BUILDDIR)/$3/$4) + cmd_sphinx = $(MAKE) BUILDDIR=$(abspath $(BUILDDIR)) $(build)=Documentation/media $2 && \ + PYTHONDONTWRITEBYTECODE=1 \ + BUILDDIR=$(abspath $(BUILDDIR)) SPHINX_CONF=$(abspath $(srctree)/$(src)/$5/$(SPHINX_CONF)) \ + $(SPHINXBUILD) \ + -b $2 \ + -c $(abspath $(srctree)/$(src)) \ + -d $(abspath $(BUILDDIR)/.doctrees/$3) \ + -D version=$(KERNELVERSION) -D release=$(KERNELRELEASE) \ + $(ALLSPHINXOPTS) \ + $(abspath $(srctree)/$(src)/$5) \ + $(abspath $(BUILDDIR)/$3/$4) + +htmldocs: + @+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,html,$(var),,$(var))) + +linkcheckdocs: + @$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,linkcheck,$(var),,$(var))) + +latexdocs: + @+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,latex,$(var),latex,$(var))) + +ifeq ($(HAVE_PDFLATEX),0) + +pdfdocs: + $(warning The '$(PDFLATEX)' command was not found. Make sure you have it installed and in PATH to produce PDF output.) + @echo " SKIP Sphinx $@ target." + +else # HAVE_PDFLATEX + +pdfdocs: latexdocs + $(foreach var,$(SPHINXDIRS), $(MAKE) PDFLATEX=$(PDFLATEX) LATEXOPTS="$(LATEXOPTS)" -C $(BUILDDIR)/$(var)/latex || exit;) + +endif # HAVE_PDFLATEX + +epubdocs: + @+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,epub,$(var),epub,$(var))) + +xmldocs: + @+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,xml,$(var),xml,$(var))) + +endif # HAVE_SPHINX + +# The following targets are independent of HAVE_SPHINX, and the rules should +# work or silently pass without Sphinx. + +# no-ops for the Sphinx toolchain +sgmldocs: + @: +psdocs: + @: +mandocs: + @: +installmandocs: + @: + +cleandocs: + $(Q)rm -rf $(BUILDDIR) + $(Q)$(MAKE) BUILDDIR=$(abspath $(BUILDDIR)) $(build)=Documentation/media clean + +dochelp: + @echo ' Linux kernel internal documentation in different formats from ReST:' + @echo ' htmldocs - HTML' + @echo ' latexdocs - LaTeX' + @echo ' pdfdocs - PDF' + @echo ' epubdocs - EPUB' + @echo ' xmldocs - XML' + @echo ' linkcheckdocs - check for broken external links (will connect to external hosts)' + @echo ' cleandocs - clean all generated files' + @echo + @echo ' make SPHINXDIRS="s1 s2" [target] Generate only docs of folder s1, s2' + @echo ' valid values for SPHINXDIRS are: $(_SPHINXDIRS)' + @echo + @echo ' make SPHINX_CONF={conf-file} [target] use *additional* sphinx-build' + @echo ' configuration. This is e.g. useful to build with nit-picking config.' diff --git a/Documentation/Makefile.sphinx b/Documentation/Makefile.sphinx deleted file mode 100644 index bcf529f6cf9b..000000000000 --- a/Documentation/Makefile.sphinx +++ /dev/null @@ -1,130 +0,0 @@ -# -*- makefile -*- -# Makefile for Sphinx documentation -# - -# You can set these variables from the command line. -SPHINXBUILD = sphinx-build -SPHINXOPTS = -SPHINXDIRS = . -_SPHINXDIRS = $(patsubst $(srctree)/Documentation/%/conf.py,%,$(wildcard $(srctree)/Documentation/*/conf.py)) -SPHINX_CONF = conf.py -PAPER = -BUILDDIR = $(obj)/output -PDFLATEX = xelatex -LATEXOPTS = -interaction=batchmode - -# User-friendly check for sphinx-build -HAVE_SPHINX := $(shell if which $(SPHINXBUILD) >/dev/null 2>&1; then echo 1; else echo 0; fi) - -ifeq ($(HAVE_SPHINX),0) - -.DEFAULT: - $(warning The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed and in PATH, or set the SPHINXBUILD make variable to point to the full path of the '$(SPHINXBUILD)' executable.) - @echo " SKIP Sphinx $@ target." - -else ifneq ($(DOCBOOKS),) - -# Skip Sphinx build if the user explicitly requested DOCBOOKS. -.DEFAULT: - @echo " SKIP Sphinx $@ target (DOCBOOKS specified)." - -else # HAVE_SPHINX - -# User-friendly check for pdflatex -HAVE_PDFLATEX := $(shell if which $(PDFLATEX) >/dev/null 2>&1; then echo 1; else echo 0; fi) - -# Internal variables. -PAPEROPT_a4 = -D latex_paper_size=a4 -PAPEROPT_letter = -D latex_paper_size=letter -KERNELDOC = $(srctree)/scripts/kernel-doc -KERNELDOC_CONF = -D kerneldoc_srctree=$(srctree) -D kerneldoc_bin=$(KERNELDOC) -ALLSPHINXOPTS = $(KERNELDOC_CONF) $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) -# the i18n builder cannot share the environment and doctrees with the others -I18NSPHINXOPTS = $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) . - -# commands; the 'cmd' from scripts/Kbuild.include is not *loopable* -loop_cmd = $(echo-cmd) $(cmd_$(1)) || exit; - -# $2 sphinx builder e.g. "html" -# $3 name of the build subfolder / e.g. "media", used as: -# * dest folder relative to $(BUILDDIR) and -# * cache folder relative to $(BUILDDIR)/.doctrees -# $4 dest subfolder e.g. "man" for man pages at media/man -# $5 reST source folder relative to $(srctree)/$(src), -# e.g. "media" for the linux-tv book-set at ./Documentation/media - -quiet_cmd_sphinx = SPHINX $@ --> file://$(abspath $(BUILDDIR)/$3/$4) - cmd_sphinx = $(MAKE) BUILDDIR=$(abspath $(BUILDDIR)) $(build)=Documentation/media $2 && \ - PYTHONDONTWRITEBYTECODE=1 \ - BUILDDIR=$(abspath $(BUILDDIR)) SPHINX_CONF=$(abspath $(srctree)/$(src)/$5/$(SPHINX_CONF)) \ - $(SPHINXBUILD) \ - -b $2 \ - -c $(abspath $(srctree)/$(src)) \ - -d $(abspath $(BUILDDIR)/.doctrees/$3) \ - -D version=$(KERNELVERSION) -D release=$(KERNELRELEASE) \ - $(ALLSPHINXOPTS) \ - $(abspath $(srctree)/$(src)/$5) \ - $(abspath $(BUILDDIR)/$3/$4) - -htmldocs: - @+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,html,$(var),,$(var))) - -linkcheckdocs: - @$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,linkcheck,$(var),,$(var))) - -latexdocs: - @+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,latex,$(var),latex,$(var))) - -ifeq ($(HAVE_PDFLATEX),0) - -pdfdocs: - $(warning The '$(PDFLATEX)' command was not found. Make sure you have it installed and in PATH to produce PDF output.) - @echo " SKIP Sphinx $@ target." - -else # HAVE_PDFLATEX - -pdfdocs: latexdocs - $(foreach var,$(SPHINXDIRS), $(MAKE) PDFLATEX=$(PDFLATEX) LATEXOPTS="$(LATEXOPTS)" -C $(BUILDDIR)/$(var)/latex || exit;) - -endif # HAVE_PDFLATEX - -epubdocs: - @+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,epub,$(var),epub,$(var))) - -xmldocs: - @+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,xml,$(var),xml,$(var))) - -endif # HAVE_SPHINX - -# The following targets are independent of HAVE_SPHINX, and the rules should -# work or silently pass without Sphinx. - -# no-ops for the Sphinx toolchain -sgmldocs: - @: -psdocs: - @: -mandocs: - @: -installmandocs: - @: - -cleandocs: - $(Q)rm -rf $(BUILDDIR) - $(Q)$(MAKE) BUILDDIR=$(abspath $(BUILDDIR)) $(build)=Documentation/media clean - -dochelp: - @echo ' Linux kernel internal documentation in different formats (Sphinx):' - @echo ' htmldocs - HTML' - @echo ' latexdocs - LaTeX' - @echo ' pdfdocs - PDF' - @echo ' epubdocs - EPUB' - @echo ' xmldocs - XML' - @echo ' linkcheckdocs - check for broken external links (will connect to external hosts)' - @echo ' cleandocs - clean all generated files' - @echo - @echo ' make SPHINXDIRS="s1 s2" [target] Generate only docs of folder s1, s2' - @echo ' valid values for SPHINXDIRS are: $(_SPHINXDIRS)' - @echo - @echo ' make SPHINX_CONF={conf-file} [target] use *additional* sphinx-build' - @echo ' configuration. This is e.g. useful to build with nit-picking config.' diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt index 1e37138027a3..618e13d5e276 100644 --- a/Documentation/PCI/MSI-HOWTO.txt +++ b/Documentation/PCI/MSI-HOWTO.txt @@ -186,7 +186,7 @@ must disable interrupts while the lock is held. If the device sends a different interrupt, the driver will deadlock trying to recursively acquire the spinlock. Such deadlocks can be avoided by using spin_lock_irqsave() or spin_lock_irq() which disable local interrupts -and acquire the lock (see Documentation/DocBook/kernel-locking). +and acquire the lock (see Documentation/kernel-hacking/locking.rst). 4.5 How to tell whether MSI/MSI-X is enabled on a device diff --git a/Documentation/RCU/00-INDEX b/Documentation/RCU/00-INDEX index 1672573b037a..f46980c060aa 100644 --- a/Documentation/RCU/00-INDEX +++ b/Documentation/RCU/00-INDEX @@ -28,8 +28,6 @@ stallwarn.txt - RCU CPU stall warnings (module parameter rcu_cpu_stall_suppress) torture.txt - RCU Torture Test Operation (CONFIG_RCU_TORTURE_TEST) -trace.txt - - CONFIG_RCU_TRACE debugfs files and formats UP.txt - RCU on Uniprocessor Systems whatisRCU.txt diff --git a/Documentation/RCU/Design/Requirements/Requirements.html b/Documentation/RCU/Design/Requirements/Requirements.html index f60adf112663..95b30fa25d56 100644 --- a/Documentation/RCU/Design/Requirements/Requirements.html +++ b/Documentation/RCU/Design/Requirements/Requirements.html @@ -559,9 +559,7 @@ The <tt>rcu_access_pointer()</tt> on line 6 is similar to For <tt>remove_gp_synchronous()</tt>, as long as all modifications to <tt>gp</tt> are carried out while holding <tt>gp_lock</tt>, the above optimizations are harmless. - However, - with <tt>CONFIG_SPARSE_RCU_POINTER=y</tt>, - <tt>sparse</tt> will complain if you + However, <tt>sparse</tt> will complain if you define <tt>gp</tt> with <tt>__rcu</tt> and then access it without using either <tt>rcu_access_pointer()</tt> or <tt>rcu_dereference()</tt>. @@ -1849,7 +1847,8 @@ mass storage, or user patience, whichever comes first. If the nesting is not visible to the compiler, as is the case with mutually recursive functions each in its own translation unit, stack overflow will result. -If the nesting takes the form of loops, either the control variable +If the nesting takes the form of loops, perhaps in the guise of tail +recursion, either the control variable will overflow or (in the Linux kernel) you will get an RCU CPU stall warning. Nevertheless, this class of RCU implementations is one of the most composable constructs in existence. @@ -1977,9 +1976,8 @@ guard against mishaps and misuse: and <tt>rcu_dereference()</tt>, perhaps (incorrectly) substituting a simple assignment. To catch this sort of error, a given RCU-protected pointer may be - tagged with <tt>__rcu</tt>, after which running sparse - with <tt>CONFIG_SPARSE_RCU_POINTER=y</tt> will complain - about simple-assignment accesses to that pointer. + tagged with <tt>__rcu</tt>, after which sparse + will complain about simple-assignment accesses to that pointer. Arnd Bergmann made me aware of this requirement, and also supplied the needed <a href="https://lwn.net/Articles/376011/">patch series</a>. @@ -2036,7 +2034,7 @@ guard against mishaps and misuse: some other synchronization mechanism, for example, reference counting. <li> In kernels built with <tt>CONFIG_RCU_TRACE=y</tt>, RCU-related - information is provided via both debugfs and event tracing. + information is provided via event tracing. <li> Open-coded use of <tt>rcu_assign_pointer()</tt> and <tt>rcu_dereference()</tt> to create typical linked data structures can be surprisingly error-prone. @@ -2519,11 +2517,7 @@ It is similarly socially unacceptable to interrupt an <tt>nohz_full</tt> CPU running in userspace. RCU must therefore track <tt>nohz_full</tt> userspace execution. -And in -<a href="https://lwn.net/Articles/558284/"><tt>CONFIG_NO_HZ_FULL_SYSIDLE=y</tt></a> -kernels, RCU must separately track idle CPUs on the one hand and -CPUs that are either idle or executing in userspace on the other. -In both cases, RCU must be able to sample state at two points in +RCU must therefore be able to sample state at two points in time, and be able to determine whether or not some other CPU spent any time idle and/or executing in userspace. @@ -2936,6 +2930,20 @@ to whether or not a CPU is online, which means that <tt>srcu_barrier()</tt> need not exclude CPU-hotplug operations. <p> +SRCU also differs from other RCU flavors in that SRCU's expedited and +non-expedited grace periods are implemented by the same mechanism. +This means that in the current SRCU implementation, expediting a +future grace period has the side effect of expediting all prior +grace periods that have not yet completed. +(But please note that this is a property of the current implementation, +not necessarily of future implementations.) +In addition, if SRCU has been idle for longer than the interval +specified by the <tt>srcutree.exp_holdoff</tt> kernel boot parameter +(25 microseconds by default), +and if a <tt>synchronize_srcu()</tt> invocation ends this idle period, +that invocation will be automatically expedited. + +<p> As of v4.12, SRCU's callbacks are maintained per-CPU, eliminating a locking bottleneck present in prior kernel versions. Although this will allow users to put much heavier stress on diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt index 877947130ebe..6beda556faf3 100644 --- a/Documentation/RCU/checklist.txt +++ b/Documentation/RCU/checklist.txt @@ -413,11 +413,11 @@ over a rather long period of time, but improvements are always welcome! read-side critical sections. It is the responsibility of the RCU update-side primitives to deal with this. -17. Use CONFIG_PROVE_RCU, CONFIG_DEBUG_OBJECTS_RCU_HEAD, and the - __rcu sparse checks (enabled by CONFIG_SPARSE_RCU_POINTER) to - validate your RCU code. These can help find problems as follows: +17. Use CONFIG_PROVE_LOCKING, CONFIG_DEBUG_OBJECTS_RCU_HEAD, and the + __rcu sparse checks to validate your RCU code. These can help + find problems as follows: - CONFIG_PROVE_RCU: check that accesses to RCU-protected data + CONFIG_PROVE_LOCKING: check that accesses to RCU-protected data structures are carried out under the proper RCU read-side critical section, while holding the right combination of locks, or whatever other conditions diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt deleted file mode 100644 index 6549012033f9..000000000000 --- a/Documentation/RCU/trace.txt +++ /dev/null @@ -1,535 +0,0 @@ -CONFIG_RCU_TRACE debugfs Files and Formats - - -The rcutree and rcutiny implementations of RCU provide debugfs trace -output that summarizes counters and state. This information is useful for -debugging RCU itself, and can sometimes also help to debug abuses of RCU. -The following sections describe the debugfs files and formats, first -for rcutree and next for rcutiny. - - -CONFIG_TREE_RCU and CONFIG_PREEMPT_RCU debugfs Files and Formats - -These implementations of RCU provide several debugfs directories under the -top-level directory "rcu": - -rcu/rcu_bh -rcu/rcu_preempt -rcu/rcu_sched - -Each directory contains files for the corresponding flavor of RCU. -Note that rcu/rcu_preempt is only present for CONFIG_PREEMPT_RCU. -For CONFIG_TREE_RCU, the RCU flavor maps onto the RCU-sched flavor, -so that activity for both appears in rcu/rcu_sched. - -In addition, the following file appears in the top-level directory: -rcu/rcutorture. This file displays rcutorture test progress. The output -of "cat rcu/rcutorture" looks as follows: - -rcutorture test sequence: 0 (test in progress) -rcutorture update version number: 615 - -The first line shows the number of rcutorture tests that have completed -since boot. If a test is currently running, the "(test in progress)" -string will appear as shown above. The second line shows the number of -update cycles that the current test has started, or zero if there is -no test in progress. - - -Within each flavor directory (rcu/rcu_bh, rcu/rcu_sched, and possibly -also rcu/rcu_preempt) the following files will be present: - -rcudata: - Displays fields in struct rcu_data. -rcuexp: - Displays statistics for expedited grace periods. -rcugp: - Displays grace-period counters. -rcuhier: - Displays the struct rcu_node hierarchy. -rcu_pending: - Displays counts of the reasons rcu_pending() decided that RCU had - work to do. -rcuboost: - Displays RCU boosting statistics. Only present if - CONFIG_RCU_BOOST=y. - -The output of "cat rcu/rcu_preempt/rcudata" looks as follows: - - 0!c=30455 g=30456 cnq=1/0:1 dt=126535/140000000000000/0 df=2002 of=4 ql=0/0 qs=N... b=10 ci=74572 nci=0 co=1131 ca=716 - 1!c=30719 g=30720 cnq=1/0:0 dt=132007/140000000000000/0 df=1874 of=10 ql=0/0 qs=N... b=10 ci=123209 nci=0 co=685 ca=982 - 2!c=30150 g=30151 cnq=1/1:1 dt=138537/140000000000000/0 df=1707 of=8 ql=0/0 qs=N... b=10 ci=80132 nci=0 co=1328 ca=1458 - 3 c=31249 g=31250 cnq=1/1:0 dt=107255/140000000000000/0 df=1749 of=6 ql=0/450 qs=NRW. b=10 ci=151700 nci=0 co=509 ca=622 - 4!c=29502 g=29503 cnq=1/0:1 dt=83647/140000000000000/0 df=965 of=5 ql=0/0 qs=N... b=10 ci=65643 nci=0 co=1373 ca=1521 - 5 c=31201 g=31202 cnq=1/0:1 dt=70422/0/0 df=535 of=7 ql=0/0 qs=.... b=10 ci=58500 nci=0 co=764 ca=698 - 6!c=30253 g=30254 cnq=1/0:1 dt=95363/140000000000000/0 df=780 of=5 ql=0/0 qs=N... b=10 ci=100607 nci=0 co=1414 ca=1353 - 7 c=31178 g=31178 cnq=1/0:0 dt=91536/0/0 df=547 of=4 ql=0/0 qs=.... b=10 ci=109819 nci=0 co=1115 ca=969 - -This file has one line per CPU, or eight for this 8-CPU system. -The fields are as follows: - -o The number at the beginning of each line is the CPU number. - CPUs numbers followed by an exclamation mark are offline, - but have been online at least once since boot. There will be - no output for CPUs that have never been online, which can be - a good thing in the surprisingly common case where NR_CPUS is - substantially larger than the number of actual CPUs. - -o "c" is the count of grace periods that this CPU believes have - completed. Offlined CPUs and CPUs in dynticks idle mode may lag - quite a ways behind, for example, CPU 4 under "rcu_sched" above, - which has been offline through 16 RCU grace periods. It is not - unusual to see offline CPUs lagging by thousands of grace periods. - Note that although the grace-period number is an unsigned long, - it is printed out as a signed long to allow more human-friendly - representation near boot time. - -o "g" is the count of grace periods that this CPU believes have - started. Again, offlined CPUs and CPUs in dynticks idle mode - may lag behind. If the "c" and "g" values are equal, this CPU - has already reported a quiescent state for the last RCU grace - period that it is aware of, otherwise, the CPU believes that it - owes RCU a quiescent state. - -o "pq" indicates that this CPU has passed through a quiescent state - for the current grace period. It is possible for "pq" to be - "1" and "c" different than "g", which indicates that although - the CPU has passed through a quiescent state, either (1) this - CPU has not yet reported that fact, (2) some other CPU has not - yet reported for this grace period, or (3) both. - -o "qp" indicates that RCU still expects a quiescent state from - this CPU. Offlined CPUs and CPUs in dyntick idle mode might - well have qp=1, which is OK: RCU is still ignoring them. - -o "dt" is the current value of the dyntick counter that is incremented - when entering or leaving idle, either due to a context switch or - due to an interrupt. This number is even if the CPU is in idle - from RCU's viewpoint and odd otherwise. The number after the - first "/" is the interrupt nesting depth when in idle state, - or a large number added to the interrupt-nesting depth when - running a non-idle task. Some architectures do not accurately - count interrupt nesting when running in non-idle kernel context, - which can result in interesting anomalies such as negative - interrupt-nesting levels. The number after the second "/" - is the NMI nesting depth. - -o "df" is the number of times that some other CPU has forced a - quiescent state on behalf of this CPU due to this CPU being in - idle state. - -o "of" is the number of times that some other CPU has forced a - quiescent state on behalf of this CPU due to this CPU being - offline. In a perfect world, this might never happen, but it - turns out that offlining and onlining a CPU can take several grace - periods, and so there is likely to be an extended period of time - when RCU believes that the CPU is online when it really is not. - Please note that erring in the other direction (RCU believing a - CPU is offline when it is really alive and kicking) is a fatal - error, so it makes sense to err conservatively. - -o "ql" is the number of RCU callbacks currently residing on - this CPU. The first number is the number of "lazy" callbacks - that are known to RCU to only be freeing memory, and the number - after the "/" is the total number of callbacks, lazy or not. - These counters count callbacks regardless of what phase of - grace-period processing that they are in (new, waiting for - grace period to start, waiting for grace period to end, ready - to invoke). - -o "qs" gives an indication of the state of the callback queue - with four characters: - - "N" Indicates that there are callbacks queued that are not - ready to be handled by the next grace period, and thus - will be handled by the grace period following the next - one. - - "R" Indicates that there are callbacks queued that are - ready to be handled by the next grace period. - - "W" Indicates that there are callbacks queued that are - waiting on the current grace period. - - "D" Indicates that there are callbacks queued that have - already been handled by a prior grace period, and are - thus waiting to be invoked. Note that callbacks in - the process of being invoked are not counted here. - Callbacks in the process of being invoked are those - that have been removed from the rcu_data structures - queues by rcu_do_batch(), but which have not yet been - invoked. - - If there are no callbacks in a given one of the above states, - the corresponding character is replaced by ".". - -o "b" is the batch limit for this CPU. If more than this number - of RCU callbacks is ready to invoke, then the remainder will - be deferred. - -o "ci" is the number of RCU callbacks that have been invoked for - this CPU. Note that ci+nci+ql is the number of callbacks that have - been registered in absence of CPU-hotplug activity. - -o "nci" is the number of RCU callbacks that have been offloaded from - this CPU. This will always be zero unless the kernel was built - with CONFIG_RCU_NOCB_CPU=y and the "rcu_nocbs=" kernel boot - parameter was specified. - -o "co" is the number of RCU callbacks that have been orphaned due to - this CPU going offline. These orphaned callbacks have been moved - to an arbitrarily chosen online CPU. - -o "ca" is the number of RCU callbacks that have been adopted by this - CPU due to other CPUs going offline. Note that ci+co-ca+ql is - the number of RCU callbacks registered on this CPU. - - -Kernels compiled with CONFIG_RCU_BOOST=y display the following from -/debug/rcu/rcu_preempt/rcudata: - - 0!c=12865 g=12866 cnq=1/0:1 dt=83113/140000000000000/0 df=288 of=11 ql=0/0 qs=N... kt=0/O ktl=944 b=10 ci=60709 nci=0 co=748 ca=871 - 1 c=14407 g=14408 cnq=1/0:0 dt=100679/140000000000000/0 df=378 of=7 ql=0/119 qs=NRW. kt=0/W ktl=9b6 b=10 ci=109740 nci=0 co=589 ca=485 - 2 c=14407 g=14408 cnq=1/0:0 dt=105486/0/0 df=90 of=9 ql=0/89 qs=NRW. kt=0/W ktl=c0c b=10 ci=83113 nci=0 co=533 ca=490 - 3 c=14407 g=14408 cnq=1/0:0 dt=107138/0/0 df=142 of=8 ql=0/188 qs=NRW. kt=0/W ktl=b96 b=10 ci=121114 nci=0 co=426 ca=290 - 4 c=14405 g=14406 cnq=1/0:1 dt=50238/0/0 df=706 of=7 ql=0/0 qs=.... kt=0/W ktl=812 b=10 ci=34929 nci=0 co=643 ca=114 - 5!c=14168 g=14169 cnq=1/0:0 dt=45465/140000000000000/0 df=161 of=11 ql=0/0 qs=N... kt=0/O ktl=b4d b=10 ci=47712 nci=0 co=677 ca=722 - 6 c=14404 g=14405 cnq=1/0:0 dt=59454/0/0 df=94 of=6 ql=0/0 qs=.... kt=0/W ktl=e57 b=10 ci=55597 nci=0 co=701 ca=811 - 7 c=14407 g=14408 cnq=1/0:1 dt=68850/0/0 df=31 of=8 ql=0/0 qs=.... kt=0/W ktl=14bd b=10 ci=77475 nci=0 co=508 ca=1042 - -This is similar to the output discussed above, but contains the following -additional fields: - -o "kt" is the per-CPU kernel-thread state. The digit preceding - the first slash is zero if there is no work pending and 1 - otherwise. The character between the first pair of slashes is - as follows: - - "S" The kernel thread is stopped, in other words, all - CPUs corresponding to this rcu_node structure are - offline. - - "R" The kernel thread is running. - - "W" The kernel thread is waiting because there is no work - for it to do. - - "O" The kernel thread is waiting because it has been - forced off of its designated CPU or because its - ->cpus_allowed mask permits it to run on other than - its designated CPU. - - "Y" The kernel thread is yielding to avoid hogging CPU. - - "?" Unknown value, indicates a bug. - - The number after the final slash is the CPU that the kthread - is actually running on. - - This field is displayed only for CONFIG_RCU_BOOST kernels. - -o "ktl" is the low-order 16 bits (in hexadecimal) of the count of - the number of times that this CPU's per-CPU kthread has gone - through its loop servicing invoke_rcu_cpu_kthread() requests. - - This field is displayed only for CONFIG_RCU_BOOST kernels. - - -The output of "cat rcu/rcu_preempt/rcuexp" looks as follows: - -s=21872 wd1=0 wd2=0 wd3=5 enq=0 sc=21872 - -These fields are as follows: - -o "s" is the sequence number, with an odd number indicating that - an expedited grace period is in progress. - -o "wd1", "wd2", and "wd3" are the number of times that an attempt - to start an expedited grace period found that someone else had - completed an expedited grace period that satisfies the attempted - request. "Our work is done." - -o "enq" is the number of quiescent states still outstanding. - -o "sc" is the number of times that the attempt to start a - new expedited grace period succeeded. - - -The output of "cat rcu/rcu_preempt/rcugp" looks as follows: - -completed=31249 gpnum=31250 age=1 max=18 - -These fields are taken from the rcu_state structure, and are as follows: - -o "completed" is the number of grace periods that have completed. - It is comparable to the "c" field from rcu/rcudata in that a - CPU whose "c" field matches the value of "completed" is aware - that the corresponding RCU grace period has completed. - -o "gpnum" is the number of grace periods that have started. It is - similarly comparable to the "g" field from rcu/rcudata in that - a CPU whose "g" field matches the value of "gpnum" is aware that - the corresponding RCU grace period has started. - - If these two fields are equal, then there is no grace period - in progress, in other words, RCU is idle. On the other hand, - if the two fields differ (as they are above), then an RCU grace - period is in progress. - -o "age" is the number of jiffies that the current grace period - has extended for, or zero if there is no grace period currently - in effect. - -o "max" is the age in jiffies of the longest-duration grace period - thus far. - -The output of "cat rcu/rcu_preempt/rcuhier" looks as follows: - -c=14407 g=14408 s=0 jfq=2 j=c863 nfqs=12040/nfqsng=0(12040) fqlh=1051 oqlen=0/0 -3/3 ..>. 0:7 ^0 -e/e ..>. 0:3 ^0 d/d ..>. 4:7 ^1 - -The fields are as follows: - -o "c" is exactly the same as "completed" under rcu/rcu_preempt/rcugp. - -o "g" is exactly the same as "gpnum" under rcu/rcu_preempt/rcugp. - -o "s" is the current state of the force_quiescent_state() - state machine. - -o "jfq" is the number of jiffies remaining for this grace period - before force_quiescent_state() is invoked to help push things - along. Note that CPUs in idle mode throughout the grace period - will not report on their own, but rather must be check by some - other CPU via force_quiescent_state(). - -o "j" is the low-order four hex digits of the jiffies counter. - Yes, Paul did run into a number of problems that turned out to - be due to the jiffies counter no longer counting. Why do you ask? - -o "nfqs" is the number of calls to force_quiescent_state() since - boot. - -o "nfqsng" is the number of useless calls to force_quiescent_state(), - where there wasn't actually a grace period active. This can - no longer happen due to grace-period processing being pushed - into a kthread. The number in parentheses is the difference - between "nfqs" and "nfqsng", or the number of times that - force_quiescent_state() actually did some real work. - -o "fqlh" is the number of calls to force_quiescent_state() that - exited immediately (without even being counted in nfqs above) - due to contention on ->fqslock. - -o Each element of the form "3/3 ..>. 0:7 ^0" represents one rcu_node - structure. Each line represents one level of the hierarchy, - from root to leaves. It is best to think of the rcu_data - structures as forming yet another level after the leaves. - Note that there might be either one, two, three, or even four - levels of rcu_node structures, depending on the relationship - between CONFIG_RCU_FANOUT, CONFIG_RCU_FANOUT_LEAF (possibly - adjusted using the rcu_fanout_leaf kernel boot parameter), and - CONFIG_NR_CPUS (possibly adjusted using the nr_cpu_ids count of - possible CPUs for the booting hardware). - - o The numbers separated by the "/" are the qsmask followed - by the qsmaskinit. The qsmask will have one bit - set for each entity in the next lower level that has - not yet checked in for the current grace period ("e" - indicating CPUs 5, 6, and 7 in the example above). - The qsmaskinit will have one bit for each entity that is - currently expected to check in during each grace period. - The value of qsmaskinit is assigned to that of qsmask - at the beginning of each grace period. - - o The characters separated by the ">" indicate the state - of the blocked-tasks lists. A "G" preceding the ">" - indicates that at least one task blocked in an RCU - read-side critical section blocks the current grace - period, while a "E" preceding the ">" indicates that - at least one task blocked in an RCU read-side critical - section blocks the current expedited grace period. - A "T" character following the ">" indicates that at - least one task is blocked within an RCU read-side - critical section, regardless of whether any current - grace period (expedited or normal) is inconvenienced. - A "." character appears if the corresponding condition - does not hold, so that "..>." indicates that no tasks - are blocked. In contrast, "GE>T" indicates maximal - inconvenience from blocked tasks. CONFIG_TREE_RCU - builds of the kernel will always show "..>.". - - o The numbers separated by the ":" are the range of CPUs - served by this struct rcu_node. This can be helpful - in working out how the hierarchy is wired together. - - For example, the example rcu_node structure shown above - has "0:7", indicating that it covers CPUs 0 through 7. - - o The number after the "^" indicates the bit in the - next higher level rcu_node structure that this rcu_node - structure corresponds to. For example, the "d/d ..>. 4:7 - ^1" has a "1" in this position, indicating that it - corresponds to the "1" bit in the "3" shown in the - "3/3 ..>. 0:7 ^0" entry on the next level up. - - -The output of "cat rcu/rcu_sched/rcu_pending" looks as follows: - - 0!np=26111 qsp=29 rpq=5386 cbr=1 cng=570 gpc=3674 gps=577 nn=15903 ndw=0 - 1!np=28913 qsp=35 rpq=6097 cbr=1 cng=448 gpc=3700 gps=554 nn=18113 ndw=0 - 2!np=32740 qsp=37 rpq=6202 cbr=0 cng=476 gpc=4627 gps=546 nn=20889 ndw=0 - 3 np=23679 qsp=22 rpq=5044 cbr=1 cng=415 gpc=3403 gps=347 nn=14469 ndw=0 - 4!np=30714 qsp=4 rpq=5574 cbr=0 cng=528 gpc=3931 gps=639 nn=20042 ndw=0 - 5 np=28910 qsp=2 rpq=5246 cbr=0 cng=428 gpc=4105 gps=709 nn=18422 ndw=0 - 6!np=38648 qsp=5 rpq=7076 cbr=0 cng=840 gpc=4072 gps=961 nn=25699 ndw=0 - 7 np=37275 qsp=2 rpq=6873 cbr=0 cng=868 gpc=3416 gps=971 nn=25147 ndw=0 - -The fields are as follows: - -o The leading number is the CPU number, with "!" indicating - an offline CPU. - -o "np" is the number of times that __rcu_pending() has been invoked - for the corresponding flavor of RCU. - -o "qsp" is the number of times that the RCU was waiting for a - quiescent state from this CPU. - -o "rpq" is the number of times that the CPU had passed through - a quiescent state, but not yet reported it to RCU. - -o "cbr" is the number of times that this CPU had RCU callbacks - that had passed through a grace period, and were thus ready - to be invoked. - -o "cng" is the number of times that this CPU needed another - grace period while RCU was idle. - -o "gpc" is the number of times that an old grace period had - completed, but this CPU was not yet aware of it. - -o "gps" is the number of times that a new grace period had started, - but this CPU was not yet aware of it. - -o "ndw" is the number of times that a wakeup of an rcuo - callback-offload kthread had to be deferred in order to avoid - deadlock. - -o "nn" is the number of times that this CPU needed nothing. - - -The output of "cat rcu/rcuboost" looks as follows: - -0:3 tasks=.... kt=W ntb=0 neb=0 nnb=0 j=c864 bt=c894 - balk: nt=0 egt=4695 bt=0 nb=0 ny=56 nos=0 -4:7 tasks=.... kt=W ntb=0 neb=0 nnb=0 j=c864 bt=c894 - balk: nt=0 egt=6541 bt=0 nb=0 ny=126 nos=0 - -This information is output only for rcu_preempt. Each two-line entry -corresponds to a leaf rcu_node structure. The fields are as follows: - -o "n:m" is the CPU-number range for the corresponding two-line - entry. In the sample output above, the first entry covers - CPUs zero through three and the second entry covers CPUs four - through seven. - -o "tasks=TNEB" gives the state of the various segments of the - rnp->blocked_tasks list: - - "T" This indicates that there are some tasks that blocked - while running on one of the corresponding CPUs while - in an RCU read-side critical section. - - "N" This indicates that some of the blocked tasks are preventing - the current normal (non-expedited) grace period from - completing. - - "E" This indicates that some of the blocked tasks are preventing - the current expedited grace period from completing. - - "B" This indicates that some of the blocked tasks are in - need of RCU priority boosting. - - Each character is replaced with "." if the corresponding - condition does not hold. - -o "kt" is the state of the RCU priority-boosting kernel - thread associated with the corresponding rcu_node structure. - The state can be one of the following: - - "S" The kernel thread is stopped, in other words, all - CPUs corresponding to this rcu_node structure are - offline. - - "R" The kernel thread is running. - - "W" The kernel thread is waiting because there is no work - for it to do. - - "Y" The kernel thread is yielding to avoid hogging CPU. - - "?" Unknown value, indicates a bug. - -o "ntb" is the number of tasks boosted. - -o "neb" is the number of tasks boosted in order to complete an - expedited grace period. - -o "nnb" is the number of tasks boosted in order to complete a - normal (non-expedited) grace period. When boosting a task - that was blocking both an expedited and a normal grace period, - it is counted against the expedited total above. - -o "j" is the low-order 16 bits of the jiffies counter in - hexadecimal. - -o "bt" is the low-order 16 bits of the value that the jiffies - counter will have when we next start boosting, assuming that - the current grace period does not end beforehand. This is - also in hexadecimal. - -o "balk: nt" counts the number of times we didn't boost (in - other words, we balked) even though it was time to boost because - there were no blocked tasks to boost. This situation occurs - when there is one blocked task on one rcu_node structure and - none on some other rcu_node structure. - -o "egt" counts the number of times we balked because although - there were blocked tasks, none of them were blocking the - current grace period, whether expedited or otherwise. - -o "bt" counts the number of times we balked because boosting - had already been initiated for the current grace period. - -o "nb" counts the number of times we balked because there - was at least one task blocking the current non-expedited grace - period that never had blocked. If it is already running, it - just won't help to boost its priority! - -o "ny" counts the number of times we balked because it was - not yet time to start boosting. - -o "nos" counts the number of times we balked for other - reasons, e.g., the grace period ended first. - - -CONFIG_TINY_RCU debugfs Files and Formats - -These implementations of RCU provides a single debugfs file under the -top-level directory RCU, namely rcu/rcudata, which displays fields in -rcu_bh_ctrlblk and rcu_sched_ctrlblk. - -The output of "cat rcu/rcudata" is as follows: - -rcu_sched: qlen: 0 -rcu_bh: qlen: 0 - -This is split into rcu_sched and rcu_bh sections. The field is as -follows: - -o "qlen" is the number of RCU callbacks currently waiting either - for an RCU grace period or waiting to be invoked. This is the - only field present for rcu_sched and rcu_bh, due to the - short-circuiting of grace period in those two cases. diff --git a/Documentation/acpi/acpi-lid.txt b/Documentation/acpi/acpi-lid.txt index 22cb3091f297..effe7af3a5af 100644 --- a/Documentation/acpi/acpi-lid.txt +++ b/Documentation/acpi/acpi-lid.txt @@ -59,20 +59,28 @@ button driver uses the following 3 modes in order not to trigger issues. If the userspace hasn't been prepared to ignore the unreliable "opened" events and the unreliable initial state notification, Linux users can use the following kernel parameters to handle the possible issues: -A. button.lid_init_state=open: +A. button.lid_init_state=method: + When this option is specified, the ACPI button driver reports the + initial lid state using the returning value of the _LID control method + and whether the "opened"/"closed" events are paired fully relies on the + firmware implementation. + This option can be used to fix some platforms where the returning value + of the _LID control method is reliable but the initial lid state + notification is missing. + This option is the default behavior during the period the userspace + isn't ready to handle the buggy AML tables. +B. button.lid_init_state=open: When this option is specified, the ACPI button driver always reports the initial lid state as "opened" and whether the "opened"/"closed" events are paired fully relies on the firmware implementation. This may fix some platforms where the returning value of the _LID control method is not reliable and the initial lid state notification is missing. - This option is the default behavior during the period the userspace - isn't ready to handle the buggy AML tables. If the userspace has been prepared to ignore the unreliable "opened" events and the unreliable initial state notification, Linux users should always use the following kernel parameter: -B. button.lid_init_state=ignore: +C. button.lid_init_state=ignore: When this option is specified, the ACPI button driver never reports the initial lid state and there is a compensation mechanism implemented to ensure that the reliable "closed" notifications can always be delievered diff --git a/Documentation/security/LoadPin.txt b/Documentation/admin-guide/LSM/LoadPin.rst index e11877f5d3d4..32070762d24c 100644 --- a/Documentation/security/LoadPin.txt +++ b/Documentation/admin-guide/LSM/LoadPin.rst @@ -1,3 +1,7 @@ +======= +LoadPin +======= + LoadPin is a Linux Security Module that ensures all kernel-loaded files (modules, firmware, etc) all originate from the same filesystem, with the expectation that such a filesystem is backed by a read-only device @@ -5,13 +9,13 @@ such as dm-verity or CDROM. This allows systems that have a verified and/or unchangeable filesystem to enforce module and firmware loading restrictions without needing to sign the files individually. -The LSM is selectable at build-time with CONFIG_SECURITY_LOADPIN, and +The LSM is selectable at build-time with ``CONFIG_SECURITY_LOADPIN``, and can be controlled at boot-time with the kernel command line option -"loadpin.enabled". By default, it is enabled, but can be disabled at -boot ("loadpin.enabled=0"). +"``loadpin.enabled``". By default, it is enabled, but can be disabled at +boot ("``loadpin.enabled=0``"). LoadPin starts pinning when it sees the first file loaded. If the block device backing the filesystem is not read-only, a sysctl is -created to toggle pinning: /proc/sys/kernel/loadpin/enabled. (Having +created to toggle pinning: ``/proc/sys/kernel/loadpin/enabled``. (Having a mutable filesystem means pinning is mutable too, but having the sysctl allows for easy testing on systems with a mutable filesystem.) diff --git a/Documentation/security/SELinux.txt b/Documentation/admin-guide/LSM/SELinux.rst index 07eae00f3314..f722c9b4173a 100644 --- a/Documentation/security/SELinux.txt +++ b/Documentation/admin-guide/LSM/SELinux.rst @@ -1,27 +1,33 @@ +======= +SELinux +======= + If you want to use SELinux, chances are you will want to use the distro-provided policies, or install the latest reference policy release from + http://oss.tresys.com/projects/refpolicy However, if you want to install a dummy policy for -testing, you can do using 'mdp' provided under +testing, you can do using ``mdp`` provided under scripts/selinux. Note that this requires the selinux userspace to be installed - in particular you will need checkpolicy to compile a kernel, and setfiles and fixfiles to label the filesystem. 1. Compile the kernel with selinux enabled. - 2. Type 'make' to compile mdp. + 2. Type ``make`` to compile ``mdp``. 3. Make sure that you are not running with SELinux enabled and a real policy. If you are, reboot with selinux disabled before continuing. - 4. Run install_policy.sh: + 4. Run install_policy.sh:: + cd scripts/selinux sh install_policy.sh Step 4 will create a new dummy policy valid for your kernel, with a single selinux user, role, and type. -It will compile the policy, will set your SELINUXTYPE to -dummy in /etc/selinux/config, install the compiled policy -as 'dummy', and relabel your filesystem. +It will compile the policy, will set your ``SELINUXTYPE`` to +``dummy`` in ``/etc/selinux/config``, install the compiled policy +as ``dummy``, and relabel your filesystem. diff --git a/Documentation/security/Smack.txt b/Documentation/admin-guide/LSM/Smack.rst index 945cc633d883..6a5826a13aea 100644 --- a/Documentation/security/Smack.txt +++ b/Documentation/admin-guide/LSM/Smack.rst @@ -1,3 +1,6 @@ +===== +Smack +===== "Good for you, you've decided to clean the elevator!" @@ -14,6 +17,7 @@ available to determine which is best suited to the problem at hand. Smack consists of three major components: + - The kernel - Basic utilities, which are helpful but not required - Configuration data @@ -39,16 +43,24 @@ The current git repository for Smack user space is: This should make and install on most modern distributions. There are five commands included in smackutil: -chsmack - display or set Smack extended attribute values -smackctl - load the Smack access rules -smackaccess - report if a process with one label has access - to an object with another +chsmack: + display or set Smack extended attribute values + +smackctl: + load the Smack access rules + +smackaccess: + report if a process with one label has access + to an object with another These two commands are obsolete with the introduction of the smackfs/load2 and smackfs/cipso2 interfaces. -smackload - properly formats data for writing to smackfs/load -smackcipso - properly formats data for writing to smackfs/cipso +smackload: + properly formats data for writing to smackfs/load + +smackcipso: + properly formats data for writing to smackfs/cipso In keeping with the intent of Smack, configuration data is minimal and not strictly required. The most important @@ -56,15 +68,15 @@ configuration step is mounting the smackfs pseudo filesystem. If smackutil is installed the startup script will take care of this, but it can be manually as well. -Add this line to /etc/fstab: +Add this line to ``/etc/fstab``:: smackfs /sys/fs/smackfs smackfs defaults 0 0 -The /sys/fs/smackfs directory is created by the kernel. +The ``/sys/fs/smackfs`` directory is created by the kernel. Smack uses extended attributes (xattrs) to store labels on filesystem objects. The attributes are stored in the extended attribute security -name space. A process must have CAP_MAC_ADMIN to change any of these +name space. A process must have ``CAP_MAC_ADMIN`` to change any of these attributes. The extended attributes that Smack uses are: @@ -73,14 +85,17 @@ SMACK64 Used to make access control decisions. In almost all cases the label given to a new filesystem object will be the label of the process that created it. + SMACK64EXEC The Smack label of a process that execs a program file with this attribute set will run with this attribute's value. + SMACK64MMAP Don't allow the file to be mmapped by a process whose Smack label does not allow all of the access permitted to a process with the label contained in this attribute. This is a very specific use case for shared libraries. + SMACK64TRANSMUTE Can only have the value "TRUE". If this attribute is present on a directory when an object is created in the directory and @@ -89,27 +104,29 @@ SMACK64TRANSMUTE gets the label of the directory instead of the label of the creating process. If the object being created is a directory the SMACK64TRANSMUTE attribute is set as well. + SMACK64IPIN This attribute is only available on file descriptors for sockets. Use the Smack label in this attribute for access control decisions on packets being delivered to this socket. + SMACK64IPOUT This attribute is only available on file descriptors for sockets. Use the Smack label in this attribute for access control decisions on packets coming from this socket. -There are multiple ways to set a Smack label on a file: +There are multiple ways to set a Smack label on a file:: # attr -S -s SMACK64 -V "value" path # chsmack -a value path A process can see the Smack label it is running with by -reading /proc/self/attr/current. A process with CAP_MAC_ADMIN +reading ``/proc/self/attr/current``. A process with ``CAP_MAC_ADMIN`` can set the process Smack by writing there. Most Smack configuration is accomplished by writing to files in the smackfs filesystem. This pseudo-filesystem is mounted -on /sys/fs/smackfs. +on ``/sys/fs/smackfs``. access Provided for backward compatibility. The access2 interface @@ -120,6 +137,7 @@ access this file. The next read will indicate whether the access would be permitted. The text will be either "1" indicating access, or "0" indicating denial. + access2 This interface reports whether a subject with the specified Smack label has a particular access to an object with a @@ -127,13 +145,17 @@ access2 this file. The next read will indicate whether the access would be permitted. The text will be either "1" indicating access, or "0" indicating denial. + ambient This contains the Smack label applied to unlabeled network packets. + change-rule This interface allows modification of existing access control rules. - The format accepted on write is: + The format accepted on write is:: + "%s %s %s %s" + where the first string is the subject label, the second the object label, the third the access to allow and the fourth the access to deny. The access strings may contain only the characters @@ -141,47 +163,63 @@ change-rule modified by enabling the permissions in the third string and disabling those in the fourth string. If there is no such rule it will be created using the access specified in the third and the fourth strings. + cipso Provided for backward compatibility. The cipso2 interface is preferred and should be used instead. This interface allows a specific CIPSO header to be assigned - to a Smack label. The format accepted on write is: + to a Smack label. The format accepted on write is:: + "%24s%4d%4d"["%4d"]... + The first string is a fixed Smack label. The first number is the level to use. The second number is the number of categories. - The following numbers are the categories. - "level-3-cats-5-19 3 2 5 19" + The following numbers are the categories:: + + "level-3-cats-5-19 3 2 5 19" + cipso2 This interface allows a specific CIPSO header to be assigned - to a Smack label. The format accepted on write is: - "%s%4d%4d"["%4d"]... + to a Smack label. The format accepted on write is:: + + "%s%4d%4d"["%4d"]... + The first string is a long Smack label. The first number is the level to use. The second number is the number of categories. - The following numbers are the categories. - "level-3-cats-5-19 3 2 5 19" + The following numbers are the categories:: + + "level-3-cats-5-19 3 2 5 19" + direct This contains the CIPSO level used for Smack direct label representation in network packets. + doi This contains the CIPSO domain of interpretation used in network packets. + ipv6host This interface allows specific IPv6 internet addresses to be treated as single label hosts. Packets are sent to single label hosts only from processes that have Smack write access to the host label. All packets received from single label hosts - are given the specified label. The format accepted on write is: + are given the specified label. The format accepted on write is:: + "%h:%h:%h:%h:%h:%h:%h:%h label" or "%h:%h:%h:%h:%h:%h:%h:%h/%d label". + The "::" address shortcut is not supported. If label is "-DELETE" a matched entry will be deleted. + load Provided for backward compatibility. The load2 interface is preferred and should be used instead. This interface allows access control rules in addition to the system defined rules to be specified. The format accepted - on write is: + on write is:: + "%24s%24s%5s" + where the first string is the subject label, the second the object label, and the third the requested access. The access string may contain only the characters "rwxat-", and specifies @@ -189,17 +227,21 @@ load permissions that are not allowed. The string "r-x--" would specify read and execute access. Labels are limited to 23 characters in length. + load2 This interface allows access control rules in addition to the system defined rules to be specified. The format accepted - on write is: + on write is:: + "%s %s %s" + where the first string is the subject label, the second the object label, and the third the requested access. The access string may contain only the characters "rwxat-", and specifies which sort of access is allowed. The "-" is a placeholder for permissions that are not allowed. The string "r-x--" would specify read and execute access. + load-self Provided for backward compatibility. The load-self2 interface is preferred and should be used instead. @@ -208,66 +250,83 @@ load-self otherwise be permitted, and are intended to provide additional restrictions on the process. The format is the same as for the load interface. + load-self2 This interface allows process specific access rules to be defined. These rules are only consulted if access would otherwise be permitted, and are intended to provide additional restrictions on the process. The format is the same as for the load2 interface. + logging This contains the Smack logging state. + mapped This contains the CIPSO level used for Smack mapped label representation in network packets. + netlabel This interface allows specific internet addresses to be treated as single label hosts. Packets are sent to single label hosts without CIPSO headers, but only from processes that have Smack write access to the host label. All packets received from single label hosts are given the specified - label. The format accepted on write is: + label. The format accepted on write is:: + "%d.%d.%d.%d label" or "%d.%d.%d.%d/%d label". + If the label specified is "-CIPSO" the address is treated as a host that supports CIPSO headers. + onlycap This contains labels processes must have for CAP_MAC_ADMIN - and CAP_MAC_OVERRIDE to be effective. If this file is empty + and ``CAP_MAC_OVERRIDE`` to be effective. If this file is empty these capabilities are effective at for processes with any label. The values are set by writing the desired labels, separated by spaces, to the file or cleared by writing "-" to the file. + ptrace This is used to define the current ptrace policy - 0 - default: this is the policy that relies on Smack access rules. - For the PTRACE_READ a subject needs to have a read access on - object. For the PTRACE_ATTACH a read-write access is required. - 1 - exact: this is the policy that limits PTRACE_ATTACH. Attach is + + 0 - default: + this is the policy that relies on Smack access rules. + For the ``PTRACE_READ`` a subject needs to have a read access on + object. For the ``PTRACE_ATTACH`` a read-write access is required. + + 1 - exact: + this is the policy that limits ``PTRACE_ATTACH``. Attach is only allowed when subject's and object's labels are equal. - PTRACE_READ is not affected. Can be overridden with CAP_SYS_PTRACE. - 2 - draconian: this policy behaves like the 'exact' above with an - exception that it can't be overridden with CAP_SYS_PTRACE. + ``PTRACE_READ`` is not affected. Can be overridden with ``CAP_SYS_PTRACE``. + + 2 - draconian: + this policy behaves like the 'exact' above with an + exception that it can't be overridden with ``CAP_SYS_PTRACE``. + revoke-subject Writing a Smack label here sets the access to '-' for all access rules with that subject label. + unconfined - If the kernel is configured with CONFIG_SECURITY_SMACK_BRINGUP - a process with CAP_MAC_ADMIN can write a label into this interface. + If the kernel is configured with ``CONFIG_SECURITY_SMACK_BRINGUP`` + a process with ``CAP_MAC_ADMIN`` can write a label into this interface. Thereafter, accesses that involve that label will be logged and the access permitted if it wouldn't be otherwise. Note that this is dangerous and can ruin the proper labeling of your system. It should never be used in production. + relabel-self This interface contains a list of labels to which the process can - transition to, by writing to /proc/self/attr/current. + transition to, by writing to ``/proc/self/attr/current``. Normally a process can change its own label to any legal value, but only - if it has CAP_MAC_ADMIN. This interface allows a process without - CAP_MAC_ADMIN to relabel itself to one of labels from predefined list. - A process without CAP_MAC_ADMIN can change its label only once. When it + if it has ``CAP_MAC_ADMIN``. This interface allows a process without + ``CAP_MAC_ADMIN`` to relabel itself to one of labels from predefined list. + A process without ``CAP_MAC_ADMIN`` can change its label only once. When it does, this list will be cleared. The values are set by writing the desired labels, separated by spaces, to the file or cleared by writing "-" to the file. If you are using the smackload utility -you can add access rules in /etc/smack/accesses. They take the form: +you can add access rules in ``/etc/smack/accesses``. They take the form:: subjectlabel objectlabel access @@ -277,14 +336,14 @@ object with objectlabel. If there is no rule no access is allowed. Look for additional programs on http://schaufler-ca.com -From the Smack Whitepaper: - -The Simplified Mandatory Access Control Kernel +The Simplified Mandatory Access Control Kernel (Whitepaper) +=========================================================== Casey Schaufler casey@schaufler-ca.com Mandatory Access Control +------------------------ Computer systems employ a variety of schemes to constrain how information is shared among the people and services using the machine. Some of these schemes @@ -297,6 +356,7 @@ access control mechanisms because you don't have a choice regarding the users or programs that have access to pieces of data. Bell & LaPadula +--------------- From the middle of the 1980's until the turn of the century Mandatory Access Control (MAC) was very closely associated with the Bell & LaPadula security @@ -306,6 +366,7 @@ within the Capital Beltway and Scandinavian supercomputer centers but was often sited as failing to address general needs. Domain Type Enforcement +----------------------- Around the turn of the century Domain Type Enforcement (DTE) became popular. This scheme organizes users, programs, and data into domains that are @@ -316,6 +377,7 @@ necessary to provide a secure domain mapping leads to the scheme being disabled or used in limited ways in the majority of cases. Smack +----- Smack is a Mandatory Access Control mechanism designed to provide useful MAC while avoiding the pitfalls of its predecessors. The limitations of Bell & @@ -326,46 +388,55 @@ Enforcement and avoided by defining access controls in terms of the access modes already in use. Smack Terminology +----------------- The jargon used to talk about Smack will be familiar to those who have dealt with other MAC systems and shouldn't be too difficult for the uninitiated to pick up. There are four terms that are used in a specific way and that are especially important: - Subject: A subject is an active entity on the computer system. + Subject: + A subject is an active entity on the computer system. On Smack a subject is a task, which is in turn the basic unit of execution. - Object: An object is a passive entity on the computer system. + Object: + An object is a passive entity on the computer system. On Smack files of all types, IPC, and tasks can be objects. - Access: Any attempt by a subject to put information into or get + Access: + Any attempt by a subject to put information into or get information from an object is an access. - Label: Data that identifies the Mandatory Access Control + Label: + Data that identifies the Mandatory Access Control characteristics of a subject or an object. These definitions are consistent with the traditional use in the security community. There are also some terms from Linux that are likely to crop up: - Capability: A task that possesses a capability has permission to + Capability: + A task that possesses a capability has permission to violate an aspect of the system security policy, as identified by the specific capability. A task that possesses one or more capabilities is a privileged task, whereas a task with no capabilities is an unprivileged task. - Privilege: A task that is allowed to violate the system security + Privilege: + A task that is allowed to violate the system security policy is said to have privilege. As of this writing a task can have privilege either by possessing capabilities or by having an effective user of root. Smack Basics +------------ Smack is an extension to a Linux system. It enforces additional restrictions on what subjects can access which objects, based on the labels attached to each of the subject and the object. Labels +~~~~~~ Smack labels are ASCII character strings. They can be up to 255 characters long, but keeping them to twenty-three characters is recommended. @@ -377,7 +448,7 @@ contain unprintable characters, the "/" (slash), the "\" (backslash), the "'" (quote) and '"' (double-quote) characters. Smack labels cannot begin with a '-'. This is reserved for special options. -There are some predefined labels: +There are some predefined labels:: _ Pronounced "floor", a single underscore character. ^ Pronounced "hat", a single circumflex character. @@ -390,14 +461,18 @@ of a process will usually be assigned by the system initialization mechanism. Access Rules +~~~~~~~~~~~~ Smack uses the traditional access modes of Linux. These modes are read, execute, write, and occasionally append. There are a few cases where the access mode may not be obvious. These include: - Signals: A signal is a write operation from the subject task to + Signals: + A signal is a write operation from the subject task to the object task. - Internet Domain IPC: Transmission of a packet is considered a + + Internet Domain IPC: + Transmission of a packet is considered a write operation from the source task to the destination task. Smack restricts access based on the label attached to a subject and the label @@ -417,6 +492,7 @@ order: 7. Any other access is denied. Smack Access Rules +~~~~~~~~~~~~~~~~~~ With the isolation provided by Smack access separation is simple. There are many interesting cases where limited access by subjects to objects with @@ -427,8 +503,9 @@ be "born" highly classified. To accommodate such schemes Smack includes a mechanism for specifying rules allowing access between labels. Access Rule Format +~~~~~~~~~~~~~~~~~~ -The format of an access rule is: +The format of an access rule is:: subject-label object-label access @@ -446,7 +523,7 @@ describe access modes: Uppercase values for the specification letters are allowed as well. Access mode specifications can be in any order. Examples of acceptable rules -are: +are:: TopSecret Secret rx Secret Unclass R @@ -456,7 +533,7 @@ are: New Old rRrRr Closed Off - -Examples of unacceptable rules are: +Examples of unacceptable rules are:: Top Secret Secret rx Ace Ace r @@ -469,6 +546,7 @@ access specifications. The dash is a placeholder, so "a-r" is the same as "ar". A lone dash is used to specify that no access should be allowed. Applying Access Rules +~~~~~~~~~~~~~~~~~~~~~ The developers of Linux rarely define new sorts of things, usually importing schemes and concepts from other systems. Most often, the other systems are @@ -511,6 +589,7 @@ one process to another requires that the sender have write access to the receiver. The receiver is not required to have read access to the sender. Setting Access Rules +~~~~~~~~~~~~~~~~~~~~ The configuration file /etc/smack/accesses contains the rules to be set at system startup. The contents are written to the special file @@ -520,6 +599,7 @@ one rule, with the most recently specified overriding any earlier specification. Task Attribute +~~~~~~~~~~~~~~ The Smack label of a process can be read from /proc/<pid>/attr/current. A process can read its own Smack label from /proc/self/attr/current. A @@ -527,12 +607,14 @@ privileged process can change its own Smack label by writing to /proc/self/attr/current but not the label of another process. File Attribute +~~~~~~~~~~~~~~ The Smack label of a filesystem object is stored as an extended attribute named SMACK64 on the file. This attribute is in the security namespace. It can only be changed by a process with privilege. Privilege +~~~~~~~~~ A process with CAP_MAC_OVERRIDE or CAP_MAC_ADMIN is privileged. CAP_MAC_OVERRIDE allows the process access to objects it would @@ -540,6 +622,7 @@ be denied otherwise. CAP_MAC_ADMIN allows a process to change Smack data, including rules and attributes. Smack Networking +~~~~~~~~~~~~~~~~ As mentioned before, Smack enforces access control on network protocol transmissions. Every packet sent by a Smack process is tagged with its Smack @@ -551,6 +634,7 @@ packet has write access to the receiving process and if that is not the case the packet is dropped. CIPSO Configuration +~~~~~~~~~~~~~~~~~~~ It is normally unnecessary to specify the CIPSO configuration. The default values used by the system handle all internal cases. Smack will compose CIPSO @@ -571,13 +655,13 @@ discarded. The DOI is 3 by default. The value can be read from The label and category set are mapped to a Smack label as defined in /etc/smack/cipso. -A Smack/CIPSO mapping has the form: +A Smack/CIPSO mapping has the form:: smack level [category [category]*] Smack does not expect the level or category sets to be related in any particular way and does not assume or assign accesses based on them. Some -examples of mappings: +examples of mappings:: TopSecret 7 TS:A,B 7 1 2 @@ -597,25 +681,30 @@ value can be read from /sys/fs/smackfs/direct and changed by writing to /sys/fs/smackfs/direct. Socket Attributes +~~~~~~~~~~~~~~~~~ There are two attributes that are associated with sockets. These attributes can only be set by privileged tasks, but any task can read them for their own sockets. - SMACK64IPIN: The Smack label of the task object. A privileged + SMACK64IPIN: + The Smack label of the task object. A privileged program that will enforce policy may set this to the star label. - SMACK64IPOUT: The Smack label transmitted with outgoing packets. + SMACK64IPOUT: + The Smack label transmitted with outgoing packets. A privileged program may set this to match the label of another task with which it hopes to communicate. Smack Netlabel Exceptions +~~~~~~~~~~~~~~~~~~~~~~~~~ You will often find that your labeled application has to talk to the outside, unlabeled world. To do this there's a special file /sys/fs/smackfs/netlabel -where you can add some exceptions in the form of : -@IP1 LABEL1 or -@IP2/MASK LABEL2 +where you can add some exceptions in the form of:: + + @IP1 LABEL1 or + @IP2/MASK LABEL2 It means that your application will have unlabeled access to @IP1 if it has write access on LABEL1, and access to the subnet @IP2/MASK if it has write @@ -624,28 +713,32 @@ access on LABEL2. Entries in the /sys/fs/smackfs/netlabel file are matched by longest mask first, like in classless IPv4 routing. -A special label '@' and an option '-CIPSO' can be used there : -@ means Internet, any application with any label has access to it --CIPSO means standard CIPSO networking +A special label '@' and an option '-CIPSO' can be used there:: -If you don't know what CIPSO is and don't plan to use it, you can just do : -echo 127.0.0.1 -CIPSO > /sys/fs/smackfs/netlabel -echo 0.0.0.0/0 @ > /sys/fs/smackfs/netlabel + @ means Internet, any application with any label has access to it + -CIPSO means standard CIPSO networking + +If you don't know what CIPSO is and don't plan to use it, you can just do:: + + echo 127.0.0.1 -CIPSO > /sys/fs/smackfs/netlabel + echo 0.0.0.0/0 @ > /sys/fs/smackfs/netlabel If you use CIPSO on your 192.168.0.0/16 local network and need also unlabeled -Internet access, you can have : -echo 127.0.0.1 -CIPSO > /sys/fs/smackfs/netlabel -echo 192.168.0.0/16 -CIPSO > /sys/fs/smackfs/netlabel -echo 0.0.0.0/0 @ > /sys/fs/smackfs/netlabel +Internet access, you can have:: + echo 127.0.0.1 -CIPSO > /sys/fs/smackfs/netlabel + echo 192.168.0.0/16 -CIPSO > /sys/fs/smackfs/netlabel + echo 0.0.0.0/0 @ > /sys/fs/smackfs/netlabel Writing Applications for Smack +------------------------------ There are three sorts of applications that will run on a Smack system. How an application interacts with Smack will determine what it will have to do to work properly under Smack. Smack Ignorant Applications +--------------------------- By far the majority of applications have no reason whatever to care about the unique properties of Smack. Since invoking a program has no impact on the @@ -653,12 +746,14 @@ Smack label associated with the process the only concern likely to arise is whether the process has execute access to the program. Smack Relevant Applications +--------------------------- Some programs can be improved by teaching them about Smack, but do not make any security decisions themselves. The utility ls(1) is one example of such a program. Smack Enforcing Applications +---------------------------- These are special programs that not only know about Smack, but participate in the enforcement of system policy. In most cases these are the programs that @@ -666,15 +761,16 @@ set up user sessions. There are also network services that provide information to processes running with various labels. File System Interfaces +---------------------- Smack maintains labels on file system objects using extended attributes. The Smack label of a file, directory, or other file system object can be obtained -using getxattr(2). +using getxattr(2):: len = getxattr("/", "security.SMACK64", value, sizeof (value)); will put the Smack label of the root directory into value. A privileged -process can set the Smack label of a file system object with setxattr(2). +process can set the Smack label of a file system object with setxattr(2):: len = strlen("Rubble"); rc = setxattr("/foo", "security.SMACK64", "Rubble", len, 0); @@ -683,17 +779,18 @@ will set the Smack label of /foo to "Rubble" if the program has appropriate privilege. Socket Interfaces +----------------- The socket attributes can be read using fgetxattr(2). A privileged process can set the Smack label of outgoing packets with -fsetxattr(2). +fsetxattr(2):: len = strlen("Rubble"); rc = fsetxattr(fd, "security.SMACK64IPOUT", "Rubble", len, 0); will set the Smack label "Rubble" on packets going out from the socket if the -program has appropriate privilege. +program has appropriate privilege:: rc = fsetxattr(fd, "security.SMACK64IPIN, "*", strlen("*"), 0); @@ -701,33 +798,40 @@ will set the Smack label "*" as the object label against which incoming packets will be checked if the program has appropriate privilege. Administration +-------------- Smack supports some mount options: - smackfsdef=label: specifies the label to give files that lack + smackfsdef=label: + specifies the label to give files that lack the Smack label extended attribute. - smackfsroot=label: specifies the label to assign the root of the + smackfsroot=label: + specifies the label to assign the root of the file system if it lacks the Smack extended attribute. - smackfshat=label: specifies a label that must have read access to + smackfshat=label: + specifies a label that must have read access to all labels set on the filesystem. Not yet enforced. - smackfsfloor=label: specifies a label to which all labels set on the + smackfsfloor=label: + specifies a label to which all labels set on the filesystem must have read access. Not yet enforced. These mount options apply to all file system types. Smack auditing +-------------- If you want Smack auditing of security events, you need to set CONFIG_AUDIT in your kernel configuration. By default, all denied events will be audited. You can change this behavior by -writing a single character to the /sys/fs/smackfs/logging file : -0 : no logging -1 : log denied (default) -2 : log accepted -3 : log denied & accepted +writing a single character to the /sys/fs/smackfs/logging file:: + + 0 : no logging + 1 : log denied (default) + 2 : log accepted + 3 : log denied & accepted Events are logged as 'key=value' pairs, for each event you at least will get the subject, the object, the rights requested, the action, the kernel function @@ -735,6 +839,7 @@ that triggered the event, plus other pairs depending on the type of event audited. Bringup Mode +------------ Bringup mode provides logging features that can make application configuration and system bringup easier. Configure the kernel with diff --git a/Documentation/security/Yama.txt b/Documentation/admin-guide/LSM/Yama.rst index d9ee7d7a6c7f..13468ea696b7 100644 --- a/Documentation/security/Yama.txt +++ b/Documentation/admin-guide/LSM/Yama.rst @@ -1,13 +1,14 @@ +==== +Yama +==== + Yama is a Linux Security Module that collects system-wide DAC security protections that are not handled by the core kernel itself. This is -selectable at build-time with CONFIG_SECURITY_YAMA, and can be controlled -at run-time through sysctls in /proc/sys/kernel/yama: - -- ptrace_scope +selectable at build-time with ``CONFIG_SECURITY_YAMA``, and can be controlled +at run-time through sysctls in ``/proc/sys/kernel/yama``: -============================================================== - -ptrace_scope: +ptrace_scope +============ As Linux grows in popularity, it will become a larger target for malware. One particularly troubling weakness of the Linux process @@ -25,47 +26,49 @@ exist and remain possible if ptrace is allowed to operate as before. Since ptrace is not commonly used by non-developers and non-admins, system builders should be allowed the option to disable this debugging system. -For a solution, some applications use prctl(PR_SET_DUMPABLE, ...) to +For a solution, some applications use ``prctl(PR_SET_DUMPABLE, ...)`` to specifically disallow such ptrace attachment (e.g. ssh-agent), but many do not. A more general solution is to only allow ptrace directly from a parent to a child process (i.e. direct "gdb EXE" and "strace EXE" still -work), or with CAP_SYS_PTRACE (i.e. "gdb --pid=PID", and "strace -p PID" +work), or with ``CAP_SYS_PTRACE`` (i.e. "gdb --pid=PID", and "strace -p PID" still work as root). In mode 1, software that has defined application-specific relationships between a debugging process and its inferior (crash handlers, etc), -prctl(PR_SET_PTRACER, pid, ...) can be used. An inferior can declare which -other process (and its descendants) are allowed to call PTRACE_ATTACH +``prctl(PR_SET_PTRACER, pid, ...)`` can be used. An inferior can declare which +other process (and its descendants) are allowed to call ``PTRACE_ATTACH`` against it. Only one such declared debugging process can exists for each inferior at a time. For example, this is used by KDE, Chromium, and Firefox's crash handlers, and by Wine for allowing only Wine processes to ptrace each other. If a process wishes to entirely disable these ptrace -restrictions, it can call prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY, ...) +restrictions, it can call ``prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY, ...)`` so that any otherwise allowed process (even those in external pid namespaces) may attach. -The sysctl settings (writable only with CAP_SYS_PTRACE) are: +The sysctl settings (writable only with ``CAP_SYS_PTRACE``) are: -0 - classic ptrace permissions: a process can PTRACE_ATTACH to any other +0 - classic ptrace permissions: + a process can ``PTRACE_ATTACH`` to any other process running under the same uid, as long as it is dumpable (i.e. did not transition uids, start privileged, or have called - prctl(PR_SET_DUMPABLE...) already). Similarly, PTRACE_TRACEME is + ``prctl(PR_SET_DUMPABLE...)`` already). Similarly, ``PTRACE_TRACEME`` is unchanged. -1 - restricted ptrace: a process must have a predefined relationship - with the inferior it wants to call PTRACE_ATTACH on. By default, +1 - restricted ptrace: + a process must have a predefined relationship + with the inferior it wants to call ``PTRACE_ATTACH`` on. By default, this relationship is that of only its descendants when the above classic criteria is also met. To change the relationship, an - inferior can call prctl(PR_SET_PTRACER, debugger, ...) to declare - an allowed debugger PID to call PTRACE_ATTACH on the inferior. - Using PTRACE_TRACEME is unchanged. + inferior can call ``prctl(PR_SET_PTRACER, debugger, ...)`` to declare + an allowed debugger PID to call ``PTRACE_ATTACH`` on the inferior. + Using ``PTRACE_TRACEME`` is unchanged. -2 - admin-only attach: only processes with CAP_SYS_PTRACE may use ptrace - with PTRACE_ATTACH, or through children calling PTRACE_TRACEME. +2 - admin-only attach: + only processes with ``CAP_SYS_PTRACE`` may use ptrace + with ``PTRACE_ATTACH``, or through children calling ``PTRACE_TRACEME``. -3 - no attach: no processes may use ptrace with PTRACE_ATTACH nor via - PTRACE_TRACEME. Once set, this sysctl value cannot be changed. +3 - no attach: + no processes may use ptrace with ``PTRACE_ATTACH`` nor via + ``PTRACE_TRACEME``. Once set, this sysctl value cannot be changed. The original children-only logic was based on the restrictions in grsecurity. - -============================================================== diff --git a/Documentation/security/apparmor.txt b/Documentation/admin-guide/LSM/apparmor.rst index 93c1fd7d0635..3e9734bd0e05 100644 --- a/Documentation/security/apparmor.txt +++ b/Documentation/admin-guide/LSM/apparmor.rst @@ -1,4 +1,9 @@ ---- What is AppArmor? --- +======== +AppArmor +======== + +What is AppArmor? +================= AppArmor is MAC style security extension for the Linux kernel. It implements a task centered policy, with task "profiles" being created and loaded @@ -6,34 +11,41 @@ from user space. Tasks on the system that do not have a profile defined for them run in an unconfined state which is equivalent to standard Linux DAC permissions. ---- How to enable/disable --- +How to enable/disable +===================== + +set ``CONFIG_SECURITY_APPARMOR=y`` -set CONFIG_SECURITY_APPARMOR=y +If AppArmor should be selected as the default security module then set:: -If AppArmor should be selected as the default security module then - set CONFIG_DEFAULT_SECURITY="apparmor" - and CONFIG_SECURITY_APPARMOR_BOOTPARAM_VALUE=1 + CONFIG_DEFAULT_SECURITY="apparmor" + CONFIG_SECURITY_APPARMOR_BOOTPARAM_VALUE=1 Build the kernel If AppArmor is not the default security module it can be enabled by passing -security=apparmor on the kernel's command line. +``security=apparmor`` on the kernel's command line. If AppArmor is the default security module it can be disabled by passing -apparmor=0, security=XXXX (where XXX is valid security module), on the -kernel's command line +``apparmor=0, security=XXXX`` (where ``XXXX`` is valid security module), on the +kernel's command line. For AppArmor to enforce any restrictions beyond standard Linux DAC permissions policy must be loaded into the kernel from user space (see the Documentation and tools links). ---- Documentation --- +Documentation +============= -Documentation can be found on the wiki. +Documentation can be found on the wiki, linked below. ---- Links --- +Links +===== Mailing List - apparmor@lists.ubuntu.com + Wiki - http://apparmor.wiki.kernel.org/ + User space tools - https://launchpad.net/apparmor + Kernel module - git://git.kernel.org/pub/scm/linux/kernel/git/jj/apparmor-dev.git diff --git a/Documentation/security/LSM.txt b/Documentation/admin-guide/LSM/index.rst index c2683f28ed36..c980dfe9abf1 100644 --- a/Documentation/security/LSM.txt +++ b/Documentation/admin-guide/LSM/index.rst @@ -1,12 +1,13 @@ -Linux Security Module framework -------------------------------- +=========================== +Linux Security Module Usage +=========================== The Linux Security Module (LSM) framework provides a mechanism for various security checks to be hooked by new kernel extensions. The name "module" is a bit of a misnomer since these extensions are not actually loadable kernel modules. Instead, they are selectable at build-time via CONFIG_DEFAULT_SECURITY and can be overridden at boot-time via the -"security=..." kernel command line argument, in the case where multiple +``"security=..."`` kernel command line argument, in the case where multiple LSMs were built into a given kernel. The primary users of the LSM interface are Mandatory Access Control @@ -19,23 +20,22 @@ in the core functionality of Linux itself. Without a specific LSM built into the kernel, the default LSM will be the Linux capabilities system. Most LSMs choose to extend the capabilities system, building their checks on top of the defined capability hooks. -For more details on capabilities, see capabilities(7) in the Linux +For more details on capabilities, see ``capabilities(7)`` in the Linux man-pages project. A list of the active security modules can be found by reading -/sys/kernel/security/lsm. This is a comma separated list, and +``/sys/kernel/security/lsm``. This is a comma separated list, and will always include the capability module. The list reflects the order in which checks are made. The capability module will always be first, followed by any "minor" modules (e.g. Yama) and then the one "major" module (e.g. SELinux) if there is one configured. -Based on https://lkml.org/lkml/2007/10/26/215, -a new LSM is accepted into the kernel when its intent (a description of -what it tries to protect against and in what cases one would expect to -use it) has been appropriately documented in Documentation/security/. -This allows an LSM's code to be easily compared to its goals, and so -that end users and distros can make a more informed decision about which -LSMs suit their requirements. +.. toctree:: + :maxdepth: 1 -For extensive documentation on the available LSM hook interfaces, please -see include/linux/security.h. + apparmor + LoadPin + SELinux + Smack + tomoyo + Yama diff --git a/Documentation/security/tomoyo.txt b/Documentation/admin-guide/LSM/tomoyo.rst index 200a2d37cbc8..a5947218fa64 100644 --- a/Documentation/security/tomoyo.txt +++ b/Documentation/admin-guide/LSM/tomoyo.rst @@ -1,21 +1,30 @@ ---- What is TOMOYO? --- +====== +TOMOYO +====== + +What is TOMOYO? +=============== TOMOYO is a name-based MAC extension (LSM module) for the Linux kernel. LiveCD-based tutorials are available at + http://tomoyo.sourceforge.jp/1.7/1st-step/ubuntu10.04-live/ -http://tomoyo.sourceforge.jp/1.7/1st-step/centos5-live/ . +http://tomoyo.sourceforge.jp/1.7/1st-step/centos5-live/ + Though these tutorials use non-LSM version of TOMOYO, they are useful for you to know what TOMOYO is. ---- How to enable TOMOYO? --- +How to enable TOMOYO? +===================== -Build the kernel with CONFIG_SECURITY_TOMOYO=y and pass "security=tomoyo" on +Build the kernel with ``CONFIG_SECURITY_TOMOYO=y`` and pass ``security=tomoyo`` on kernel's command line. Please see http://tomoyo.sourceforge.jp/2.3/ for details. ---- Where is documentation? --- +Where is documentation? +======================= User <-> Kernel interface documentation is available at http://tomoyo.sourceforge.jp/2.3/policy-reference.html . @@ -42,7 +51,8 @@ History of TOMOYO? Realities of Mainlining http://sourceforge.jp/projects/tomoyo/docs/lfj2008.pdf ---- What is future plan? --- +What is future plan? +==================== We believe that inode based security and name based security are complementary and both should be used together. But unfortunately, so far, we cannot enable diff --git a/Documentation/admin-guide/README.rst b/Documentation/admin-guide/README.rst index b96e80f79e85..b5343c5aa224 100644 --- a/Documentation/admin-guide/README.rst +++ b/Documentation/admin-guide/README.rst @@ -55,12 +55,6 @@ Documentation contains information about the problems, which may result by upgrading your kernel. - - The Documentation/DocBook/ subdirectory contains several guides for - kernel developers and users. These guides can be rendered in a - number of formats: PostScript (.ps), PDF, HTML, & man-pages, among others. - After installation, ``make psdocs``, ``make pdfdocs``, ``make htmldocs``, - or ``make mandocs`` will render the documentation in the requested format. - Installing the kernel source ---------------------------- diff --git a/Documentation/admin-guide/devices.txt b/Documentation/admin-guide/devices.txt index c9cea2e39c21..6b71852dadc2 100644 --- a/Documentation/admin-guide/devices.txt +++ b/Documentation/admin-guide/devices.txt @@ -369,8 +369,10 @@ 237 = /dev/loop-control Loopback control device 238 = /dev/vhost-net Host kernel accelerator for virtio net 239 = /dev/uhid User-space I/O driver support for HID subsystem + 240 = /dev/userio Serio driver testing device + 241 = /dev/vhost-vsock Host kernel driver for virtio vsock - 240-254 Reserved for local use + 242-254 Reserved for local use 255 Reserved for MISC_DYNAMIC_MINOR 11 char Raw keyboard device (Linux/SPARC only) diff --git a/Documentation/admin-guide/index.rst b/Documentation/admin-guide/index.rst index 8c60a8a32a1a..5bb9161dbe6a 100644 --- a/Documentation/admin-guide/index.rst +++ b/Documentation/admin-guide/index.rst @@ -61,6 +61,8 @@ configure specific aspects of kernel behavior to your liking. java ras pm/index + thunderbolt + LSM/index .. only:: subproject and html diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 15f79c27748d..f24ee1c99412 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -649,6 +649,13 @@ /proc/<pid>/coredump_filter. See also Documentation/filesystems/proc.txt. + coresight_cpu_debug.enable + [ARM,ARM64] + Format: <bool> + Enable/disable the CPU sampling based debugging. + 0: default value, disable debugging + 1: enable debugging at boot time + cpuidle.off=1 [CPU_IDLE] disable the cpuidle sub-system @@ -720,7 +727,8 @@ See also Documentation/input/joystick-parport.txt ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot - time. See Documentation/dynamic-debug-howto.txt for + time. See + Documentation/admin-guide/dynamic-debug-howto.rst for details. Deprecated, see dyndbg. debug [KNL] Enable kernel debugging (events log level). @@ -866,6 +874,15 @@ dscc4.setup= [NET] + dt_cpu_ftrs= [PPC] + Format: {"off" | "known"} + Control how the dt_cpu_ftrs device-tree binding is + used for CPU feature discovery and setup (if it + exists). + off: Do not use it, fall back to legacy cpu table. + known: Do not pass through unknown features to guests + or userspace, only those that the kernel is aware of. + dump_apple_properties [X86] Dump name and content of EFI device properties on x86 Macs. Useful for driver authors to determine @@ -874,7 +891,8 @@ dyndbg[="val"] [KNL,DYNAMIC_DEBUG] module.dyndbg[="val"] Enable debug messages at boot time. See - Documentation/dynamic-debug-howto.txt for details. + Documentation/admin-guide/dynamic-debug-howto.rst + for details. nompx [X86] Disables Intel Memory Protection Extensions. See Documentation/x86/intel_mpx.txt for more @@ -945,6 +963,12 @@ must already be setup and configured. Options are not yet supported. + owl,<addr> + Start an early, polled-mode console on a serial port + of an Actions Semi SoC, such as S500 or S900, at the + specified address. The serial port must already be + setup and configured. Options are not yet supported. + smh Use ARM semihosting calls for early console. s3c2410,<addr> @@ -1477,12 +1501,21 @@ in crypto/hash_info.h. ima_policy= [IMA] - The builtin measurement policy to load during IMA - setup. Specyfing "tcb" as the value, measures all - programs exec'd, files mmap'd for exec, and all files - opened with the read mode bit set by either the - effective uid (euid=0) or uid=0. - Format: "tcb" + The builtin policies to load during IMA setup. + Format: "tcb | appraise_tcb | secure_boot" + + The "tcb" policy measures all programs exec'd, files + mmap'd for exec, and all files opened with the read + mode bit set by either the effective uid (euid=0) or + uid=0. + + The "appraise_tcb" policy appraises the integrity of + all files owned by root. (This is the equivalent + of ima_appraise_tcb.) + + The "secure_boot" policy appraises the integrity + of files (eg. kexec kernel image, kernel modules, + firmware, policy, etc) based on file signatures. ima_tcb [IMA] Deprecated. Use ima_policy= instead. Load a policy which meets the needs of the Trusted @@ -2127,6 +2160,12 @@ memmap=nn[KMG]@ss[KMG] [KNL] Force usage of a specific region of memory. Region of memory to be used is from ss to ss+nn. + If @ss[KMG] is omitted, it is equivalent to mem=nn[KMG], + which limits max address to nn[KMG]. + Multiple different regions can be specified, + comma delimited. + Example: + memmap=100M@2G,100M#3G,1G!1024G memmap=nn[KMG]#ss[KMG] [KNL,ACPI] Mark specific memory as ACPI data. @@ -2139,6 +2178,9 @@ memmap=64K$0x18690000 or memmap=0x10000$0x18690000 + Some bootloaders may need an escape character before '$', + like Grub2, otherwise '$' and the following number + will be eaten. memmap=nn[KMG]!ss[KMG] [KNL,X86] Mark specific memory as protected. @@ -3229,21 +3271,17 @@ rcutree.gp_cleanup_delay= [KNL] Set the number of jiffies to delay each step of - RCU grace-period cleanup. This only has effect - when CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP is set. + RCU grace-period cleanup. rcutree.gp_init_delay= [KNL] Set the number of jiffies to delay each step of - RCU grace-period initialization. This only has - effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT - is set. + RCU grace-period initialization. rcutree.gp_preinit_delay= [KNL] Set the number of jiffies to delay each step of RCU grace-period pre-initialization, that is, the propagation of recent CPU-hotplug changes up - the rcu_node combining tree. This only has effect - when CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT is set. + the rcu_node combining tree. rcutree.rcu_fanout_exact= [KNL] Disable autobalancing of the rcu_node combining @@ -3319,6 +3357,17 @@ This wake_up() will be accompanied by a WARN_ONCE() splat and an ftrace_dump(). + rcuperf.gp_async= [KNL] + Measure performance of asynchronous + grace-period primitives such as call_rcu(). + + rcuperf.gp_async_max= [KNL] + Specify the maximum number of outstanding + callbacks per writer thread. When a writer + thread exceeds this limit, it invokes the + corresponding flavor of rcu_barrier() to allow + previously posted callbacks to drain. + rcuperf.gp_exp= [KNL] Measure performance of expedited synchronous grace-period primitives. @@ -3346,17 +3395,22 @@ rcuperf.perf_runnable= [BOOT] Start rcuperf running at boot time. + rcuperf.perf_type= [KNL] + Specify the RCU implementation to test. + rcuperf.shutdown= [KNL] Shut the system down after performance tests complete. This is useful for hands-off automated testing. - rcuperf.perf_type= [KNL] - Specify the RCU implementation to test. - rcuperf.verbose= [KNL] Enable additional printk() statements. + rcuperf.writer_holdoff= [KNL] + Write-side holdoff between grace periods, + in microseconds. The default of zero says + no holdoff. + rcutorture.cbflood_inter_holdoff= [KNL] Set holdoff time (jiffies) between successive callback-flood tests. @@ -3794,6 +3848,15 @@ spia_pedr= spia_peddr= + srcutree.counter_wrap_check [KNL] + Specifies how frequently to check for + grace-period sequence counter wrap for the + srcu_data structure's ->srcu_gp_seq_needed field. + The greater the number of bits set in this kernel + parameter, the less frequently counter wrap will + be checked for. Note that the bottom two bits + are ignored. + srcutree.exp_holdoff [KNL] Specifies how many nanoseconds must elapse since the end of the last SRCU grace period for @@ -3802,6 +3865,13 @@ expediting. Set to zero to disable automatic expediting. + stack_guard_gap= [MM] + override the default stack gap protection. The value + is in page units and it defines how many pages prior + to (for stacks growing down) resp. after (for stacks + growing up) the main stack are reserved for no other + mapping. Default value is 256 pages. + stacktrace [FTRACE] Enabled the stack tracer on boot up. diff --git a/Documentation/admin-guide/pm/cpufreq.rst b/Documentation/admin-guide/pm/cpufreq.rst index 289c80f7760e..463cf7e73db8 100644 --- a/Documentation/admin-guide/pm/cpufreq.rst +++ b/Documentation/admin-guide/pm/cpufreq.rst @@ -1,4 +1,5 @@ .. |struct cpufreq_policy| replace:: :c:type:`struct cpufreq_policy <cpufreq_policy>` +.. |intel_pstate| replace:: :doc:`intel_pstate <intel_pstate>` ======================= CPU Performance Scaling @@ -75,7 +76,7 @@ feedback registers, as that information is typically specific to the hardware interface it comes from and may not be easily represented in an abstract, platform-independent way. For this reason, ``CPUFreq`` allows scaling drivers to bypass the governor layer and implement their own performance scaling -algorithms. That is done by the ``intel_pstate`` scaling driver. +algorithms. That is done by the |intel_pstate| scaling driver. ``CPUFreq`` Policy Objects @@ -174,13 +175,13 @@ necessary to restart the scaling governor so that it can take the new online CPU into account. That is achieved by invoking the governor's ``->stop`` and ``->start()`` callbacks, in this order, for the entire policy. -As mentioned before, the ``intel_pstate`` scaling driver bypasses the scaling +As mentioned before, the |intel_pstate| scaling driver bypasses the scaling governor layer of ``CPUFreq`` and provides its own P-state selection algorithms. -Consequently, if ``intel_pstate`` is used, scaling governors are not attached to +Consequently, if |intel_pstate| is used, scaling governors are not attached to new policy objects. Instead, the driver's ``->setpolicy()`` callback is invoked to register per-CPU utilization update callbacks for each policy. These callbacks are invoked by the CPU scheduler in the same way as for scaling -governors, but in the ``intel_pstate`` case they both determine the P-state to +governors, but in the |intel_pstate| case they both determine the P-state to use and change the hardware configuration accordingly in one go from scheduler context. @@ -257,7 +258,7 @@ are the following: ``scaling_available_governors`` List of ``CPUFreq`` scaling governors present in the kernel that can - be attached to this policy or (if the ``intel_pstate`` scaling driver is + be attached to this policy or (if the |intel_pstate| scaling driver is in use) list of scaling algorithms provided by the driver that can be applied to this policy. @@ -268,29 +269,29 @@ are the following: ``scaling_cur_freq`` Current frequency of all of the CPUs belonging to this policy (in kHz). - For the majority of scaling drivers, this is the frequency of the last - P-state requested by the driver from the hardware using the scaling + In the majority of cases, this is the frequency of the last P-state + requested by the scaling driver from the hardware using the scaling interface provided by it, which may or may not reflect the frequency the CPU is actually running at (due to hardware design and other limitations). - Some scaling drivers (e.g. ``intel_pstate``) attempt to provide - information more precisely reflecting the current CPU frequency through - this attribute, but that still may not be the exact current CPU - frequency as seen by the hardware at the moment. + Some architectures (e.g. ``x86``) may attempt to provide information + more precisely reflecting the current CPU frequency through this + attribute, but that still may not be the exact current CPU frequency as + seen by the hardware at the moment. ``scaling_driver`` The scaling driver currently in use. ``scaling_governor`` The scaling governor currently attached to this policy or (if the - ``intel_pstate`` scaling driver is in use) the scaling algorithm + |intel_pstate| scaling driver is in use) the scaling algorithm provided by the driver that is currently applied to this policy. This attribute is read-write and writing to it will cause a new scaling governor to be attached to this policy or a new scaling algorithm provided by the scaling driver to be applied to it (in the - ``intel_pstate`` case), as indicated by the string written to this + |intel_pstate| case), as indicated by the string written to this attribute (which must be one of the names listed by the ``scaling_available_governors`` attribute described above). @@ -619,7 +620,7 @@ This file is located under :file:`/sys/devices/system/cpu/cpufreq/` and controls the "boost" setting for the whole system. It is not present if the underlying scaling driver does not support the frequency boost mechanism (or supports it, but provides a driver-specific interface for controlling it, like -``intel_pstate``). +|intel_pstate|). If the value in this file is 1, the frequency boost mechanism is enabled. This means that either the hardware can be put into states in which it is able to diff --git a/Documentation/admin-guide/pm/index.rst b/Documentation/admin-guide/pm/index.rst index c80f087321fc..7f148f76f432 100644 --- a/Documentation/admin-guide/pm/index.rst +++ b/Documentation/admin-guide/pm/index.rst @@ -6,6 +6,7 @@ Power Management :maxdepth: 2 cpufreq + intel_pstate .. only:: subproject and html diff --git a/Documentation/admin-guide/pm/intel_pstate.rst b/Documentation/admin-guide/pm/intel_pstate.rst new file mode 100644 index 000000000000..1d6249825efc --- /dev/null +++ b/Documentation/admin-guide/pm/intel_pstate.rst @@ -0,0 +1,753 @@ +=============================================== +``intel_pstate`` CPU Performance Scaling Driver +=============================================== + +:: + + Copyright (c) 2017 Intel Corp., Rafael J. Wysocki <rafael.j.wysocki@intel.com> + + +General Information +=================== + +``intel_pstate`` is a part of the +:doc:`CPU performance scaling subsystem <cpufreq>` in the Linux kernel +(``CPUFreq``). It is a scaling driver for the Sandy Bridge and later +generations of Intel processors. Note, however, that some of those processors +may not be supported. [To understand ``intel_pstate`` it is necessary to know +how ``CPUFreq`` works in general, so this is the time to read :doc:`cpufreq` if +you have not done that yet.] + +For the processors supported by ``intel_pstate``, the P-state concept is broader +than just an operating frequency or an operating performance point (see the +`LinuxCon Europe 2015 presentation by Kristen Accardi <LCEU2015_>`_ for more +information about that). For this reason, the representation of P-states used +by ``intel_pstate`` internally follows the hardware specification (for details +refer to `Intel® 64 and IA-32 Architectures Software Developer’s Manual +Volume 3: System Programming Guide <SDM_>`_). However, the ``CPUFreq`` core +uses frequencies for identifying operating performance points of CPUs and +frequencies are involved in the user space interface exposed by it, so +``intel_pstate`` maps its internal representation of P-states to frequencies too +(fortunately, that mapping is unambiguous). At the same time, it would not be +practical for ``intel_pstate`` to supply the ``CPUFreq`` core with a table of +available frequencies due to the possible size of it, so the driver does not do +that. Some functionality of the core is limited by that. + +Since the hardware P-state selection interface used by ``intel_pstate`` is +available at the logical CPU level, the driver always works with individual +CPUs. Consequently, if ``intel_pstate`` is in use, every ``CPUFreq`` policy +object corresponds to one logical CPU and ``CPUFreq`` policies are effectively +equivalent to CPUs. In particular, this means that they become "inactive" every +time the corresponding CPU is taken offline and need to be re-initialized when +it goes back online. + +``intel_pstate`` is not modular, so it cannot be unloaded, which means that the +only way to pass early-configuration-time parameters to it is via the kernel +command line. However, its configuration can be adjusted via ``sysfs`` to a +great extent. In some configurations it even is possible to unregister it via +``sysfs`` which allows another ``CPUFreq`` scaling driver to be loaded and +registered (see `below <status_attr_>`_). + + +Operation Modes +=============== + +``intel_pstate`` can operate in three different modes: in the active mode with +or without hardware-managed P-states support and in the passive mode. Which of +them will be in effect depends on what kernel command line options are used and +on the capabilities of the processor. + +Active Mode +----------- + +This is the default operation mode of ``intel_pstate``. If it works in this +mode, the ``scaling_driver`` policy attribute in ``sysfs`` for all ``CPUFreq`` +policies contains the string "intel_pstate". + +In this mode the driver bypasses the scaling governors layer of ``CPUFreq`` and +provides its own scaling algorithms for P-state selection. Those algorithms +can be applied to ``CPUFreq`` policies in the same way as generic scaling +governors (that is, through the ``scaling_governor`` policy attribute in +``sysfs``). [Note that different P-state selection algorithms may be chosen for +different policies, but that is not recommended.] + +They are not generic scaling governors, but their names are the same as the +names of some of those governors. Moreover, confusingly enough, they generally +do not work in the same way as the generic governors they share the names with. +For example, the ``powersave`` P-state selection algorithm provided by +``intel_pstate`` is not a counterpart of the generic ``powersave`` governor +(roughly, it corresponds to the ``schedutil`` and ``ondemand`` governors). + +There are two P-state selection algorithms provided by ``intel_pstate`` in the +active mode: ``powersave`` and ``performance``. The way they both operate +depends on whether or not the hardware-managed P-states (HWP) feature has been +enabled in the processor and possibly on the processor model. + +Which of the P-state selection algorithms is used by default depends on the +:c:macro:`CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE` kernel configuration option. +Namely, if that option is set, the ``performance`` algorithm will be used by +default, and the other one will be used by default if it is not set. + +Active Mode With HWP +~~~~~~~~~~~~~~~~~~~~ + +If the processor supports the HWP feature, it will be enabled during the +processor initialization and cannot be disabled after that. It is possible +to avoid enabling it by passing the ``intel_pstate=no_hwp`` argument to the +kernel in the command line. + +If the HWP feature has been enabled, ``intel_pstate`` relies on the processor to +select P-states by itself, but still it can give hints to the processor's +internal P-state selection logic. What those hints are depends on which P-state +selection algorithm has been applied to the given policy (or to the CPU it +corresponds to). + +Even though the P-state selection is carried out by the processor automatically, +``intel_pstate`` registers utilization update callbacks with the CPU scheduler +in this mode. However, they are not used for running a P-state selection +algorithm, but for periodic updates of the current CPU frequency information to +be made available from the ``scaling_cur_freq`` policy attribute in ``sysfs``. + +HWP + ``performance`` +..................... + +In this configuration ``intel_pstate`` will write 0 to the processor's +Energy-Performance Preference (EPP) knob (if supported) or its +Energy-Performance Bias (EPB) knob (otherwise), which means that the processor's +internal P-state selection logic is expected to focus entirely on performance. + +This will override the EPP/EPB setting coming from the ``sysfs`` interface +(see `Energy vs Performance Hints`_ below). + +Also, in this configuration the range of P-states available to the processor's +internal P-state selection logic is always restricted to the upper boundary +(that is, the maximum P-state that the driver is allowed to use). + +HWP + ``powersave`` +................... + +In this configuration ``intel_pstate`` will set the processor's +Energy-Performance Preference (EPP) knob (if supported) or its +Energy-Performance Bias (EPB) knob (otherwise) to whatever value it was +previously set to via ``sysfs`` (or whatever default value it was +set to by the platform firmware). This usually causes the processor's +internal P-state selection logic to be less performance-focused. + +Active Mode Without HWP +~~~~~~~~~~~~~~~~~~~~~~~ + +This is the default operation mode for processors that do not support the HWP +feature. It also is used by default with the ``intel_pstate=no_hwp`` argument +in the kernel command line. However, in this mode ``intel_pstate`` may refuse +to work with the given processor if it does not recognize it. [Note that +``intel_pstate`` will never refuse to work with any processor with the HWP +feature enabled.] + +In this mode ``intel_pstate`` registers utilization update callbacks with the +CPU scheduler in order to run a P-state selection algorithm, either +``powersave`` or ``performance``, depending on the ``scaling_cur_freq`` policy +setting in ``sysfs``. The current CPU frequency information to be made +available from the ``scaling_cur_freq`` policy attribute in ``sysfs`` is +periodically updated by those utilization update callbacks too. + +``performance`` +............... + +Without HWP, this P-state selection algorithm is always the same regardless of +the processor model and platform configuration. + +It selects the maximum P-state it is allowed to use, subject to limits set via +``sysfs``, every time the driver configuration for the given CPU is updated +(e.g. via ``sysfs``). + +This is the default P-state selection algorithm if the +:c:macro:`CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE` kernel configuration option +is set. + +``powersave`` +............. + +Without HWP, this P-state selection algorithm generally depends on the +processor model and/or the system profile setting in the ACPI tables and there +are two variants of it. + +One of them is used with processors from the Atom line and (regardless of the +processor model) on platforms with the system profile in the ACPI tables set to +"mobile" (laptops mostly), "tablet", "appliance PC", "desktop", or +"workstation". It is also used with processors supporting the HWP feature if +that feature has not been enabled (that is, with the ``intel_pstate=no_hwp`` +argument in the kernel command line). It is similar to the algorithm +implemented by the generic ``schedutil`` scaling governor except that the +utilization metric used by it is based on numbers coming from feedback +registers of the CPU. It generally selects P-states proportional to the +current CPU utilization, so it is referred to as the "proportional" algorithm. + +The second variant of the ``powersave`` P-state selection algorithm, used in all +of the other cases (generally, on processors from the Core line, so it is +referred to as the "Core" algorithm), is based on the values read from the APERF +and MPERF feedback registers and the previously requested target P-state. +It does not really take CPU utilization into account explicitly, but as a rule +it causes the CPU P-state to ramp up very quickly in response to increased +utilization which is generally desirable in server environments. + +Regardless of the variant, this algorithm is run by the driver's utilization +update callback for the given CPU when it is invoked by the CPU scheduler, but +not more often than every 10 ms (that can be tweaked via ``debugfs`` in `this +particular case <Tuning Interface in debugfs_>`_). Like in the ``performance`` +case, the hardware configuration is not touched if the new P-state turns out to +be the same as the current one. + +This is the default P-state selection algorithm if the +:c:macro:`CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE` kernel configuration option +is not set. + +Passive Mode +------------ + +This mode is used if the ``intel_pstate=passive`` argument is passed to the +kernel in the command line (it implies the ``intel_pstate=no_hwp`` setting too). +Like in the active mode without HWP support, in this mode ``intel_pstate`` may +refuse to work with the given processor if it does not recognize it. + +If the driver works in this mode, the ``scaling_driver`` policy attribute in +``sysfs`` for all ``CPUFreq`` policies contains the string "intel_cpufreq". +Then, the driver behaves like a regular ``CPUFreq`` scaling driver. That is, +it is invoked by generic scaling governors when necessary to talk to the +hardware in order to change the P-state of a CPU (in particular, the +``schedutil`` governor can invoke it directly from scheduler context). + +While in this mode, ``intel_pstate`` can be used with all of the (generic) +scaling governors listed by the ``scaling_available_governors`` policy attribute +in ``sysfs`` (and the P-state selection algorithms described above are not +used). Then, it is responsible for the configuration of policy objects +corresponding to CPUs and provides the ``CPUFreq`` core (and the scaling +governors attached to the policy objects) with accurate information on the +maximum and minimum operating frequencies supported by the hardware (including +the so-called "turbo" frequency ranges). In other words, in the passive mode +the entire range of available P-states is exposed by ``intel_pstate`` to the +``CPUFreq`` core. However, in this mode the driver does not register +utilization update callbacks with the CPU scheduler and the ``scaling_cur_freq`` +information comes from the ``CPUFreq`` core (and is the last frequency selected +by the current scaling governor for the given policy). + + +.. _turbo: + +Turbo P-states Support +====================== + +In the majority of cases, the entire range of P-states available to +``intel_pstate`` can be divided into two sub-ranges that correspond to +different types of processor behavior, above and below a boundary that +will be referred to as the "turbo threshold" in what follows. + +The P-states above the turbo threshold are referred to as "turbo P-states" and +the whole sub-range of P-states they belong to is referred to as the "turbo +range". These names are related to the Turbo Boost technology allowing a +multicore processor to opportunistically increase the P-state of one or more +cores if there is enough power to do that and if that is not going to cause the +thermal envelope of the processor package to be exceeded. + +Specifically, if software sets the P-state of a CPU core within the turbo range +(that is, above the turbo threshold), the processor is permitted to take over +performance scaling control for that core and put it into turbo P-states of its +choice going forward. However, that permission is interpreted differently by +different processor generations. Namely, the Sandy Bridge generation of +processors will never use any P-states above the last one set by software for +the given core, even if it is within the turbo range, whereas all of the later +processor generations will take it as a license to use any P-states from the +turbo range, even above the one set by software. In other words, on those +processors setting any P-state from the turbo range will enable the processor +to put the given core into all turbo P-states up to and including the maximum +supported one as it sees fit. + +One important property of turbo P-states is that they are not sustainable. More +precisely, there is no guarantee that any CPUs will be able to stay in any of +those states indefinitely, because the power distribution within the processor +package may change over time or the thermal envelope it was designed for might +be exceeded if a turbo P-state was used for too long. + +In turn, the P-states below the turbo threshold generally are sustainable. In +fact, if one of them is set by software, the processor is not expected to change +it to a lower one unless in a thermal stress or a power limit violation +situation (a higher P-state may still be used if it is set for another CPU in +the same package at the same time, for example). + +Some processors allow multiple cores to be in turbo P-states at the same time, +but the maximum P-state that can be set for them generally depends on the number +of cores running concurrently. The maximum turbo P-state that can be set for 3 +cores at the same time usually is lower than the analogous maximum P-state for +2 cores, which in turn usually is lower than the maximum turbo P-state that can +be set for 1 core. The one-core maximum turbo P-state is thus the maximum +supported one overall. + +The maximum supported turbo P-state, the turbo threshold (the maximum supported +non-turbo P-state) and the minimum supported P-state are specific to the +processor model and can be determined by reading the processor's model-specific +registers (MSRs). Moreover, some processors support the Configurable TDP +(Thermal Design Power) feature and, when that feature is enabled, the turbo +threshold effectively becomes a configurable value that can be set by the +platform firmware. + +Unlike ``_PSS`` objects in the ACPI tables, ``intel_pstate`` always exposes +the entire range of available P-states, including the whole turbo range, to the +``CPUFreq`` core and (in the passive mode) to generic scaling governors. This +generally causes turbo P-states to be set more often when ``intel_pstate`` is +used relative to ACPI-based CPU performance scaling (see `below <acpi-cpufreq_>`_ +for more information). + +Moreover, since ``intel_pstate`` always knows what the real turbo threshold is +(even if the Configurable TDP feature is enabled in the processor), its +``no_turbo`` attribute in ``sysfs`` (described `below <no_turbo_attr_>`_) should +work as expected in all cases (that is, if set to disable turbo P-states, it +always should prevent ``intel_pstate`` from using them). + + +Processor Support +================= + +To handle a given processor ``intel_pstate`` requires a number of different +pieces of information on it to be known, including: + + * The minimum supported P-state. + + * The maximum supported `non-turbo P-state <turbo_>`_. + + * Whether or not turbo P-states are supported at all. + + * The maximum supported `one-core turbo P-state <turbo_>`_ (if turbo P-states + are supported). + + * The scaling formula to translate the driver's internal representation + of P-states into frequencies and the other way around. + +Generally, ways to obtain that information are specific to the processor model +or family. Although it often is possible to obtain all of it from the processor +itself (using model-specific registers), there are cases in which hardware +manuals need to be consulted to get to it too. + +For this reason, there is a list of supported processors in ``intel_pstate`` and +the driver initialization will fail if the detected processor is not in that +list, unless it supports the `HWP feature <Active Mode_>`_. [The interface to +obtain all of the information listed above is the same for all of the processors +supporting the HWP feature, which is why they all are supported by +``intel_pstate``.] + + +User Space Interface in ``sysfs`` +================================= + +Global Attributes +----------------- + +``intel_pstate`` exposes several global attributes (files) in ``sysfs`` to +control its functionality at the system level. They are located in the +``/sys/devices/system/cpu/cpufreq/intel_pstate/`` directory and affect all +CPUs. + +Some of them are not present if the ``intel_pstate=per_cpu_perf_limits`` +argument is passed to the kernel in the command line. + +``max_perf_pct`` + Maximum P-state the driver is allowed to set in percent of the + maximum supported performance level (the highest supported `turbo + P-state <turbo_>`_). + + This attribute will not be exposed if the + ``intel_pstate=per_cpu_perf_limits`` argument is present in the kernel + command line. + +``min_perf_pct`` + Minimum P-state the driver is allowed to set in percent of the + maximum supported performance level (the highest supported `turbo + P-state <turbo_>`_). + + This attribute will not be exposed if the + ``intel_pstate=per_cpu_perf_limits`` argument is present in the kernel + command line. + +``num_pstates`` + Number of P-states supported by the processor (between 0 and 255 + inclusive) including both turbo and non-turbo P-states (see + `Turbo P-states Support`_). + + The value of this attribute is not affected by the ``no_turbo`` + setting described `below <no_turbo_attr_>`_. + + This attribute is read-only. + +``turbo_pct`` + Ratio of the `turbo range <turbo_>`_ size to the size of the entire + range of supported P-states, in percent. + + This attribute is read-only. + +.. _no_turbo_attr: + +``no_turbo`` + If set (equal to 1), the driver is not allowed to set any turbo P-states + (see `Turbo P-states Support`_). If unset (equalt to 0, which is the + default), turbo P-states can be set by the driver. + [Note that ``intel_pstate`` does not support the general ``boost`` + attribute (supported by some other scaling drivers) which is replaced + by this one.] + + This attrubute does not affect the maximum supported frequency value + supplied to the ``CPUFreq`` core and exposed via the policy interface, + but it affects the maximum possible value of per-policy P-state limits + (see `Interpretation of Policy Attributes`_ below for details). + +.. _status_attr: + +``status`` + Operation mode of the driver: "active", "passive" or "off". + + "active" + The driver is functional and in the `active mode + <Active Mode_>`_. + + "passive" + The driver is functional and in the `passive mode + <Passive Mode_>`_. + + "off" + The driver is not functional (it is not registered as a scaling + driver with the ``CPUFreq`` core). + + This attribute can be written to in order to change the driver's + operation mode or to unregister it. The string written to it must be + one of the possible values of it and, if successful, the write will + cause the driver to switch over to the operation mode represented by + that string - or to be unregistered in the "off" case. [Actually, + switching over from the active mode to the passive mode or the other + way around causes the driver to be unregistered and registered again + with a different set of callbacks, so all of its settings (the global + as well as the per-policy ones) are then reset to their default + values, possibly depending on the target operation mode.] + + That only is supported in some configurations, though (for example, if + the `HWP feature is enabled in the processor <Active Mode With HWP_>`_, + the operation mode of the driver cannot be changed), and if it is not + supported in the current configuration, writes to this attribute with + fail with an appropriate error. + +Interpretation of Policy Attributes +----------------------------------- + +The interpretation of some ``CPUFreq`` policy attributes described in +:doc:`cpufreq` is special with ``intel_pstate`` as the current scaling driver +and it generally depends on the driver's `operation mode <Operation Modes_>`_. + +First of all, the values of the ``cpuinfo_max_freq``, ``cpuinfo_min_freq`` and +``scaling_cur_freq`` attributes are produced by applying a processor-specific +multiplier to the internal P-state representation used by ``intel_pstate``. +Also, the values of the ``scaling_max_freq`` and ``scaling_min_freq`` +attributes are capped by the frequency corresponding to the maximum P-state that +the driver is allowed to set. + +If the ``no_turbo`` `global attribute <no_turbo_attr_>`_ is set, the driver is +not allowed to use turbo P-states, so the maximum value of ``scaling_max_freq`` +and ``scaling_min_freq`` is limited to the maximum non-turbo P-state frequency. +Accordingly, setting ``no_turbo`` causes ``scaling_max_freq`` and +``scaling_min_freq`` to go down to that value if they were above it before. +However, the old values of ``scaling_max_freq`` and ``scaling_min_freq`` will be +restored after unsetting ``no_turbo``, unless these attributes have been written +to after ``no_turbo`` was set. + +If ``no_turbo`` is not set, the maximum possible value of ``scaling_max_freq`` +and ``scaling_min_freq`` corresponds to the maximum supported turbo P-state, +which also is the value of ``cpuinfo_max_freq`` in either case. + +Next, the following policy attributes have special meaning if +``intel_pstate`` works in the `active mode <Active Mode_>`_: + +``scaling_available_governors`` + List of P-state selection algorithms provided by ``intel_pstate``. + +``scaling_governor`` + P-state selection algorithm provided by ``intel_pstate`` currently in + use with the given policy. + +``scaling_cur_freq`` + Frequency of the average P-state of the CPU represented by the given + policy for the time interval between the last two invocations of the + driver's utilization update callback by the CPU scheduler for that CPU. + +The meaning of these attributes in the `passive mode <Passive Mode_>`_ is the +same as for other scaling drivers. + +Additionally, the value of the ``scaling_driver`` attribute for ``intel_pstate`` +depends on the operation mode of the driver. Namely, it is either +"intel_pstate" (in the `active mode <Active Mode_>`_) or "intel_cpufreq" (in the +`passive mode <Passive Mode_>`_). + +Coordination of P-State Limits +------------------------------ + +``intel_pstate`` allows P-state limits to be set in two ways: with the help of +the ``max_perf_pct`` and ``min_perf_pct`` `global attributes +<Global Attributes_>`_ or via the ``scaling_max_freq`` and ``scaling_min_freq`` +``CPUFreq`` policy attributes. The coordination between those limits is based +on the following rules, regardless of the current operation mode of the driver: + + 1. All CPUs are affected by the global limits (that is, none of them can be + requested to run faster than the global maximum and none of them can be + requested to run slower than the global minimum). + + 2. Each individual CPU is affected by its own per-policy limits (that is, it + cannot be requested to run faster than its own per-policy maximum and it + cannot be requested to run slower than its own per-policy minimum). + + 3. The global and per-policy limits can be set independently. + +If the `HWP feature is enabled in the processor <Active Mode With HWP_>`_, the +resulting effective values are written into its registers whenever the limits +change in order to request its internal P-state selection logic to always set +P-states within these limits. Otherwise, the limits are taken into account by +scaling governors (in the `passive mode <Passive Mode_>`_) and by the driver +every time before setting a new P-state for a CPU. + +Additionally, if the ``intel_pstate=per_cpu_perf_limits`` command line argument +is passed to the kernel, ``max_perf_pct`` and ``min_perf_pct`` are not exposed +at all and the only way to set the limits is by using the policy attributes. + + +Energy vs Performance Hints +--------------------------- + +If ``intel_pstate`` works in the `active mode with the HWP feature enabled +<Active Mode With HWP_>`_ in the processor, additional attributes are present +in every ``CPUFreq`` policy directory in ``sysfs``. They are intended to allow +user space to help ``intel_pstate`` to adjust the processor's internal P-state +selection logic by focusing it on performance or on energy-efficiency, or +somewhere between the two extremes: + +``energy_performance_preference`` + Current value of the energy vs performance hint for the given policy + (or the CPU represented by it). + + The hint can be changed by writing to this attribute. + +``energy_performance_available_preferences`` + List of strings that can be written to the + ``energy_performance_preference`` attribute. + + They represent different energy vs performance hints and should be + self-explanatory, except that ``default`` represents whatever hint + value was set by the platform firmware. + +Strings written to the ``energy_performance_preference`` attribute are +internally translated to integer values written to the processor's +Energy-Performance Preference (EPP) knob (if supported) or its +Energy-Performance Bias (EPB) knob. + +[Note that tasks may by migrated from one CPU to another by the scheduler's +load-balancing algorithm and if different energy vs performance hints are +set for those CPUs, that may lead to undesirable outcomes. To avoid such +issues it is better to set the same energy vs performance hint for all CPUs +or to pin every task potentially sensitive to them to a specific CPU.] + +.. _acpi-cpufreq: + +``intel_pstate`` vs ``acpi-cpufreq`` +==================================== + +On the majority of systems supported by ``intel_pstate``, the ACPI tables +provided by the platform firmware contain ``_PSS`` objects returning information +that can be used for CPU performance scaling (refer to the `ACPI specification`_ +for details on the ``_PSS`` objects and the format of the information returned +by them). + +The information returned by the ACPI ``_PSS`` objects is used by the +``acpi-cpufreq`` scaling driver. On systems supported by ``intel_pstate`` +the ``acpi-cpufreq`` driver uses the same hardware CPU performance scaling +interface, but the set of P-states it can use is limited by the ``_PSS`` +output. + +On those systems each ``_PSS`` object returns a list of P-states supported by +the corresponding CPU which basically is a subset of the P-states range that can +be used by ``intel_pstate`` on the same system, with one exception: the whole +`turbo range <turbo_>`_ is represented by one item in it (the topmost one). By +convention, the frequency returned by ``_PSS`` for that item is greater by 1 MHz +than the frequency of the highest non-turbo P-state listed by it, but the +corresponding P-state representation (following the hardware specification) +returned for it matches the maximum supported turbo P-state (or is the +special value 255 meaning essentially "go as high as you can get"). + +The list of P-states returned by ``_PSS`` is reflected by the table of +available frequencies supplied by ``acpi-cpufreq`` to the ``CPUFreq`` core and +scaling governors and the minimum and maximum supported frequencies reported by +it come from that list as well. In particular, given the special representation +of the turbo range described above, this means that the maximum supported +frequency reported by ``acpi-cpufreq`` is higher by 1 MHz than the frequency +of the highest supported non-turbo P-state listed by ``_PSS`` which, of course, +affects decisions made by the scaling governors, except for ``powersave`` and +``performance``. + +For example, if a given governor attempts to select a frequency proportional to +estimated CPU load and maps the load of 100% to the maximum supported frequency +(possibly multiplied by a constant), then it will tend to choose P-states below +the turbo threshold if ``acpi-cpufreq`` is used as the scaling driver, because +in that case the turbo range corresponds to a small fraction of the frequency +band it can use (1 MHz vs 1 GHz or more). In consequence, it will only go to +the turbo range for the highest loads and the other loads above 50% that might +benefit from running at turbo frequencies will be given non-turbo P-states +instead. + +One more issue related to that may appear on systems supporting the +`Configurable TDP feature <turbo_>`_ allowing the platform firmware to set the +turbo threshold. Namely, if that is not coordinated with the lists of P-states +returned by ``_PSS`` properly, there may be more than one item corresponding to +a turbo P-state in those lists and there may be a problem with avoiding the +turbo range (if desirable or necessary). Usually, to avoid using turbo +P-states overall, ``acpi-cpufreq`` simply avoids using the topmost state listed +by ``_PSS``, but that is not sufficient when there are other turbo P-states in +the list returned by it. + +Apart from the above, ``acpi-cpufreq`` works like ``intel_pstate`` in the +`passive mode <Passive Mode_>`_, except that the number of P-states it can set +is limited to the ones listed by the ACPI ``_PSS`` objects. + + +Kernel Command Line Options for ``intel_pstate`` +================================================ + +Several kernel command line options can be used to pass early-configuration-time +parameters to ``intel_pstate`` in order to enforce specific behavior of it. All +of them have to be prepended with the ``intel_pstate=`` prefix. + +``disable`` + Do not register ``intel_pstate`` as the scaling driver even if the + processor is supported by it. + +``passive`` + Register ``intel_pstate`` in the `passive mode <Passive Mode_>`_ to + start with. + + This option implies the ``no_hwp`` one described below. + +``force`` + Register ``intel_pstate`` as the scaling driver instead of + ``acpi-cpufreq`` even if the latter is preferred on the given system. + + This may prevent some platform features (such as thermal controls and + power capping) that rely on the availability of ACPI P-states + information from functioning as expected, so it should be used with + caution. + + This option does not work with processors that are not supported by + ``intel_pstate`` and on platforms where the ``pcc-cpufreq`` scaling + driver is used instead of ``acpi-cpufreq``. + +``no_hwp`` + Do not enable the `hardware-managed P-states (HWP) feature + <Active Mode With HWP_>`_ even if it is supported by the processor. + +``hwp_only`` + Register ``intel_pstate`` as the scaling driver only if the + `hardware-managed P-states (HWP) feature <Active Mode With HWP_>`_ is + supported by the processor. + +``support_acpi_ppc`` + Take ACPI ``_PPC`` performance limits into account. + + If the preferred power management profile in the FADT (Fixed ACPI + Description Table) is set to "Enterprise Server" or "Performance + Server", the ACPI ``_PPC`` limits are taken into account by default + and this option has no effect. + +``per_cpu_perf_limits`` + Use per-logical-CPU P-State limits (see `Coordination of P-state + Limits`_ for details). + + +Diagnostics and Tuning +====================== + +Trace Events +------------ + +There are two static trace events that can be used for ``intel_pstate`` +diagnostics. One of them is the ``cpu_frequency`` trace event generally used +by ``CPUFreq``, and the other one is the ``pstate_sample`` trace event specific +to ``intel_pstate``. Both of them are triggered by ``intel_pstate`` only if +it works in the `active mode <Active Mode_>`_. + +The following sequence of shell commands can be used to enable them and see +their output (if the kernel is generally configured to support event tracing):: + + # cd /sys/kernel/debug/tracing/ + # echo 1 > events/power/pstate_sample/enable + # echo 1 > events/power/cpu_frequency/enable + # cat trace + gnome-terminal--4510 [001] ..s. 1177.680733: pstate_sample: core_busy=107 scaled=94 from=26 to=26 mperf=1143818 aperf=1230607 tsc=29838618 freq=2474476 + cat-5235 [002] ..s. 1177.681723: cpu_frequency: state=2900000 cpu_id=2 + +If ``intel_pstate`` works in the `passive mode <Passive Mode_>`_, the +``cpu_frequency`` trace event will be triggered either by the ``schedutil`` +scaling governor (for the policies it is attached to), or by the ``CPUFreq`` +core (for the policies with other scaling governors). + +``ftrace`` +---------- + +The ``ftrace`` interface can be used for low-level diagnostics of +``intel_pstate``. For example, to check how often the function to set a +P-state is called, the ``ftrace`` filter can be set to to +:c:func:`intel_pstate_set_pstate`:: + + # cd /sys/kernel/debug/tracing/ + # cat available_filter_functions | grep -i pstate + intel_pstate_set_pstate + intel_pstate_cpu_init + ... + # echo intel_pstate_set_pstate > set_ftrace_filter + # echo function > current_tracer + # cat trace | head -15 + # tracer: function + # + # entries-in-buffer/entries-written: 80/80 #P:4 + # + # _-----=> irqs-off + # / _----=> need-resched + # | / _---=> hardirq/softirq + # || / _--=> preempt-depth + # ||| / delay + # TASK-PID CPU# |||| TIMESTAMP FUNCTION + # | | | |||| | | + Xorg-3129 [000] ..s. 2537.644844: intel_pstate_set_pstate <-intel_pstate_timer_func + gnome-terminal--4510 [002] ..s. 2537.649844: intel_pstate_set_pstate <-intel_pstate_timer_func + gnome-shell-3409 [001] ..s. 2537.650850: intel_pstate_set_pstate <-intel_pstate_timer_func + <idle>-0 [000] ..s. 2537.654843: intel_pstate_set_pstate <-intel_pstate_timer_func + +Tuning Interface in ``debugfs`` +------------------------------- + +The ``powersave`` algorithm provided by ``intel_pstate`` for `the Core line of +processors in the active mode <powersave_>`_ is based on a `PID controller`_ +whose parameters were chosen to address a number of different use cases at the +same time. However, it still is possible to fine-tune it to a specific workload +and the ``debugfs`` interface under ``/sys/kernel/debug/pstate_snb/`` is +provided for this purpose. [Note that the ``pstate_snb`` directory will be +present only if the specific P-state selection algorithm matching the interface +in it actually is in use.] + +The following files present in that directory can be used to modify the PID +controller parameters at run time: + +| ``deadband`` +| ``d_gain_pct`` +| ``i_gain_pct`` +| ``p_gain_pct`` +| ``sample_rate_ms`` +| ``setpoint`` + +Note, however, that achieving desirable results this way generally requires +expert-level understanding of the power vs performance tradeoff, so extra care +is recommended when attempting to do that. + + +.. _LCEU2015: http://events.linuxfoundation.org/sites/events/files/slides/LinuxConEurope_2015.pdf +.. _SDM: http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-system-programming-manual-325384.html +.. _ACPI specification: http://www.uefi.org/sites/default/files/resources/ACPI_6_1.pdf +.. _PID controller: https://en.wikipedia.org/wiki/PID_controller diff --git a/Documentation/admin-guide/ras.rst b/Documentation/admin-guide/ras.rst index 8c7bbf2c88d2..197896718f81 100644 --- a/Documentation/admin-guide/ras.rst +++ b/Documentation/admin-guide/ras.rst @@ -344,9 +344,9 @@ for more than 2 channels, like Fully Buffered DIMMs (FB-DIMMs) memory controllers. The following example will assume 2 channels: +------------+-----------------------+ - | Chip | Channels | - | Select +-----------+-----------+ - | rows | ``ch0`` | ``ch1`` | + | CS Rows | Channels | + +------------+-----------+-----------+ + | | ``ch0`` | ``ch1`` | +============+===========+===========+ | ``csrow0`` | DIMM_A0 | DIMM_B0 | +------------+ | | @@ -698,7 +698,7 @@ information indicating that errors have been detected:: The structure of the message is: +---------------------------------------+-------------+ - | Content + Example | + | Content | Example | +=======================================+=============+ | The memory controller | MC0 | +---------------------------------------+-------------+ @@ -713,7 +713,7 @@ The structure of the message is: +---------------------------------------+-------------+ | The error syndrome | 0xb741 | +---------------------------------------+-------------+ - | Memory row | row 0 + + | Memory row | row 0 | +---------------------------------------+-------------+ | Memory channel | channel 1 | +---------------------------------------+-------------+ diff --git a/Documentation/admin-guide/thunderbolt.rst b/Documentation/admin-guide/thunderbolt.rst new file mode 100644 index 000000000000..6a4cd1f159ca --- /dev/null +++ b/Documentation/admin-guide/thunderbolt.rst @@ -0,0 +1,199 @@ +============= + Thunderbolt +============= +The interface presented here is not meant for end users. Instead there +should be a userspace tool that handles all the low-level details, keeps +database of the authorized devices and prompts user for new connections. + +More details about the sysfs interface for Thunderbolt devices can be +found in ``Documentation/ABI/testing/sysfs-bus-thunderbolt``. + +Those users who just want to connect any device without any sort of +manual work, can add following line to +``/etc/udev/rules.d/99-local.rules``:: + + ACTION=="add", SUBSYSTEM=="thunderbolt", ATTR{authorized}=="0", ATTR{authorized}="1" + +This will authorize all devices automatically when they appear. However, +keep in mind that this bypasses the security levels and makes the system +vulnerable to DMA attacks. + +Security levels and how to use them +----------------------------------- +Starting from Intel Falcon Ridge Thunderbolt controller there are 4 +security levels available. The reason for these is the fact that the +connected devices can be DMA masters and thus read contents of the host +memory without CPU and OS knowing about it. There are ways to prevent +this by setting up an IOMMU but it is not always available for various +reasons. + +The security levels are as follows: + + none + All devices are automatically connected by the firmware. No user + approval is needed. In BIOS settings this is typically called + *Legacy mode*. + + user + User is asked whether the device is allowed to be connected. + Based on the device identification information available through + ``/sys/bus/thunderbolt/devices``. user then can do the decision. + In BIOS settings this is typically called *Unique ID*. + + secure + User is asked whether the device is allowed to be connected. In + addition to UUID the device (if it supports secure connect) is sent + a challenge that should match the expected one based on a random key + written to ``key`` sysfs attribute. In BIOS settings this is + typically called *One time saved key*. + + dponly + The firmware automatically creates tunnels for Display Port and + USB. No PCIe tunneling is done. In BIOS settings this is + typically called *Display Port Only*. + +The current security level can be read from +``/sys/bus/thunderbolt/devices/domainX/security`` where ``domainX`` is +the Thunderbolt domain the host controller manages. There is typically +one domain per Thunderbolt host controller. + +If the security level reads as ``user`` or ``secure`` the connected +device must be authorized by the user before PCIe tunnels are created +(e.g the PCIe device appears). + +Each Thunderbolt device plugged in will appear in sysfs under +``/sys/bus/thunderbolt/devices``. The device directory carries +information that can be used to identify the particular device, +including its name and UUID. + +Authorizing devices when security level is ``user`` or ``secure`` +----------------------------------------------------------------- +When a device is plugged in it will appear in sysfs as follows:: + + /sys/bus/thunderbolt/devices/0-1/authorized - 0 + /sys/bus/thunderbolt/devices/0-1/device - 0x8004 + /sys/bus/thunderbolt/devices/0-1/device_name - Thunderbolt to FireWire Adapter + /sys/bus/thunderbolt/devices/0-1/vendor - 0x1 + /sys/bus/thunderbolt/devices/0-1/vendor_name - Apple, Inc. + /sys/bus/thunderbolt/devices/0-1/unique_id - e0376f00-0300-0100-ffff-ffffffffffff + +The ``authorized`` attribute reads 0 which means no PCIe tunnels are +created yet. The user can authorize the device by simply:: + + # echo 1 > /sys/bus/thunderbolt/devices/0-1/authorized + +This will create the PCIe tunnels and the device is now connected. + +If the device supports secure connect, and the domain security level is +set to ``secure``, it has an additional attribute ``key`` which can hold +a random 32 byte value used for authorization and challenging the device in +future connects:: + + /sys/bus/thunderbolt/devices/0-3/authorized - 0 + /sys/bus/thunderbolt/devices/0-3/device - 0x305 + /sys/bus/thunderbolt/devices/0-3/device_name - AKiTiO Thunder3 PCIe Box + /sys/bus/thunderbolt/devices/0-3/key - + /sys/bus/thunderbolt/devices/0-3/vendor - 0x41 + /sys/bus/thunderbolt/devices/0-3/vendor_name - inXtron + /sys/bus/thunderbolt/devices/0-3/unique_id - dc010000-0000-8508-a22d-32ca6421cb16 + +Notice the key is empty by default. + +If the user does not want to use secure connect it can just ``echo 1`` +to the ``authorized`` attribute and the PCIe tunnels will be created in +the same way than in ``user`` security level. + +If the user wants to use secure connect, the first time the device is +plugged a key needs to be created and send to the device:: + + # key=$(openssl rand -hex 32) + # echo $key > /sys/bus/thunderbolt/devices/0-3/key + # echo 1 > /sys/bus/thunderbolt/devices/0-3/authorized + +Now the device is connected (PCIe tunnels are created) and in addition +the key is stored on the device NVM. + +Next time the device is plugged in the user can verify (challenge) the +device using the same key:: + + # echo $key > /sys/bus/thunderbolt/devices/0-3/key + # echo 2 > /sys/bus/thunderbolt/devices/0-3/authorized + +If the challenge the device returns back matches the one we expect based +on the key, the device is connected and the PCIe tunnels are created. +However, if the challenge failed no tunnels are created and error is +returned to the user. + +If the user still wants to connect the device it can either approve +the device without a key or write new key and write 1 to the +``authorized`` file to get the new key stored on the device NVM. + +Upgrading NVM on Thunderbolt device or host +------------------------------------------- +Since most of the functionality is handled in a firmware running on a +host controller or a device, it is important that the firmware can be +upgraded to the latest where possible bugs in it have been fixed. +Typically OEMs provide this firmware from their support site. + +There is also a central site which has links where to download firmwares +for some machines: + + `Thunderbolt Updates <https://thunderbolttechnology.net/updates>`_ + +Before you upgrade firmware on a device or host, please make sure it is +the suitable. Failing to do that may render the device (or host) in a +state where it cannot be used properly anymore without special tools! + +Host NVM upgrade on Apple Macs is not supported. + +Once the NVM image has been downloaded, you need to plug in a +Thunderbolt device so that the host controller appears. It does not +matter which device is connected (unless you are upgrading NVM on a +device - then you need to connect that particular device). + +Note OEM-specific method to power the controller up ("force power") may +be available for your system in which case there is no need to plug in a +Thunderbolt device. + +After that we can write the firmware to the non-active parts of the NVM +of the host or device. As an example here is how Intel NUC6i7KYK (Skull +Canyon) Thunderbolt controller NVM is upgraded:: + + # dd if=KYK_TBT_FW_0018.bin of=/sys/bus/thunderbolt/devices/0-0/nvm_non_active0/nvmem + +Once the operation completes we can trigger NVM authentication and +upgrade process as follows:: + + # echo 1 > /sys/bus/thunderbolt/devices/0-0/nvm_authenticate + +If no errors are returned, the host controller shortly disappears. Once +it comes back the driver notices it and initiates a full power cycle. +After a while the host controller appears again and this time it should +be fully functional. + +We can verify that the new NVM firmware is active by running following +commands:: + + # cat /sys/bus/thunderbolt/devices/0-0/nvm_authenticate + 0x0 + # cat /sys/bus/thunderbolt/devices/0-0/nvm_version + 18.0 + +If ``nvm_authenticate`` contains anything else than 0x0 it is the error +code from the last authentication cycle, which means the authentication +of the NVM image failed. + +Note names of the NVMem devices ``nvm_activeN`` and ``nvm_non_activeN`` +depends on the order they are registered in the NVMem subsystem. N in +the name is the identifier added by the NVMem subsystem. + +Upgrading NVM when host controller is in safe mode +-------------------------------------------------- +If the existing NVM is not properly authenticated (or is missing) the +host controller goes into safe mode which means that only available +functionality is flashing new NVM image. When in this mode the reading +``nvm_version`` fails with ``ENODATA`` and the device identification +information is missing. + +To recover from this mode, one needs to flash a valid NVM image to the +host host controller in the same way it is done in the previous chapter. diff --git a/Documentation/arm/Atmel/README b/Documentation/arm/Atmel/README index 6ca78f818dbf..afb13c15389d 100644 --- a/Documentation/arm/Atmel/README +++ b/Documentation/arm/Atmel/README @@ -16,7 +16,7 @@ git branches/tags and email subject always contain this "at91" sub-string. AT91 SoCs --------- -Documentation and detailled datasheet for each product are available on +Documentation and detailed datasheet for each product are available on the Atmel website: http://www.atmel.com. Flavors: @@ -101,6 +101,42 @@ the Atmel website: http://www.atmel.com. + Datasheet http://www.atmel.com/Images/Atmel-11267-32-bit-Cortex-A5-Microcontroller-SAMA5D2_Datasheet.pdf + * ARM Cortex-M7 MCUs + - sams70 family + - sams70j19 + - sams70j20 + - sams70j21 + - sams70n19 + - sams70n20 + - sams70n21 + - sams70q19 + - sams70q20 + - sams70q21 + + Datasheet + http://www.atmel.com/Images/Atmel-11242-32-bit-Cortex-M7-Microcontroller-SAM-S70Q-SAM-S70N-SAM-S70J_Datasheet.pdf + + - samv70 family + - samv70j19 + - samv70j20 + - samv70n19 + - samv70n20 + - samv70q19 + - samv70q20 + + Datasheet + http://www.atmel.com/Images/Atmel-11297-32-bit-Cortex-M7-Microcontroller-SAM-V70Q-SAM-V70N-SAM-V70J_Datasheet.pdf + + - samv71 family + - samv71j19 + - samv71j20 + - samv71j21 + - samv71n19 + - samv71n20 + - samv71n21 + - samv71q19 + - samv71q20 + - samv71q21 + + Datasheet + http://www.atmel.com/Images/Atmel-44003-32-bit-Cortex-M7-Microcontroller-SAM-V71Q-SAM-V71N-SAM-V71J_Datasheet.pdf Linux kernel information ------------------------ diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt index 01ddeaf64b0f..9490f2845f06 100644 --- a/Documentation/block/biodoc.txt +++ b/Documentation/block/biodoc.txt @@ -632,7 +632,7 @@ to i/o submission, if the bio fields are likely to be accessed after the i/o is issued (since the bio may otherwise get freed in case i/o completion happens in the meantime). -The bio_clone() routine may be used to duplicate a bio, where the clone +The bio_clone_fast() routine may be used to duplicate a bio, where the clone shares the bio_vec_list with the original bio (i.e. both point to the same bio_vec_list). This would typically be used for splitting i/o requests in lvm or md. diff --git a/Documentation/conf.py b/Documentation/conf.py index bacf9d337c89..71b032bb44fd 100644 --- a/Documentation/conf.py +++ b/Documentation/conf.py @@ -271,8 +271,7 @@ latex_elements = { # Additional stuff for the LaTeX preamble. 'preamble': ''' - % Adjust margins - \\usepackage[margin=0.5in, top=1in, bottom=1in]{geometry} + \\usepackage{ifthen} % Allow generate some pages in landscape \\usepackage{lscape} @@ -281,6 +280,7 @@ latex_elements = { \\definecolor{NoteColor}{RGB}{204,255,255} \\definecolor{WarningColor}{RGB}{255,204,204} \\definecolor{AttentionColor}{RGB}{255,255,204} + \\definecolor{ImportantColor}{RGB}{192,255,204} \\definecolor{OtherColor}{RGB}{204,204,204} \\newlength{\\mynoticelength} \\makeatletter\\newenvironment{coloredbox}[1]{% @@ -301,7 +301,12 @@ latex_elements = { \\ifthenelse% {\\equal{\\py@noticetype}{attention}}% {\\colorbox{AttentionColor}{\\usebox{\\@tempboxa}}}% - {\\colorbox{OtherColor}{\\usebox{\\@tempboxa}}}% + {% + \\ifthenelse% + {\\equal{\\py@noticetype}{important}}% + {\\colorbox{ImportantColor}{\\usebox{\\@tempboxa}}}% + {\\colorbox{OtherColor}{\\usebox{\\@tempboxa}}}% + }% }% }% }\\makeatother @@ -336,30 +341,51 @@ latex_elements = { if major == 1 and minor > 3: latex_elements['preamble'] += '\\renewcommand*{\\DUrole}[2]{ #2 }\n' +if major == 1 and minor <= 4: + latex_elements['preamble'] += '\\usepackage[margin=0.5in, top=1in, bottom=1in]{geometry}' +elif major == 1 and (minor > 5 or (minor == 5 and patch >= 3)): + latex_elements['sphinxsetup'] = 'hmargin=0.5in, vmargin=0.5in' + + # Grouping the document tree into LaTeX files. List of tuples # (source start file, target name, title, # author, documentclass [howto, manual, or own class]). +# Sorted in alphabetical order latex_documents = [ - ('doc-guide/index', 'kernel-doc-guide.tex', 'Linux Kernel Documentation Guide', - 'The kernel development community', 'manual'), ('admin-guide/index', 'linux-user.tex', 'Linux Kernel User Documentation', 'The kernel development community', 'manual'), ('core-api/index', 'core-api.tex', 'The kernel core API manual', 'The kernel development community', 'manual'), - ('driver-api/index', 'driver-api.tex', 'The kernel driver API manual', + ('crypto/index', 'crypto-api.tex', 'Linux Kernel Crypto API manual', 'The kernel development community', 'manual'), - ('input/index', 'linux-input.tex', 'The Linux input driver subsystem', + ('dev-tools/index', 'dev-tools.tex', 'Development tools for the Kernel', 'The kernel development community', 'manual'), - ('kernel-documentation', 'kernel-documentation.tex', 'The Linux Kernel Documentation', + ('doc-guide/index', 'kernel-doc-guide.tex', 'Linux Kernel Documentation Guide', 'The kernel development community', 'manual'), - ('process/index', 'development-process.tex', 'Linux Kernel Development Documentation', + ('driver-api/index', 'driver-api.tex', 'The kernel driver API manual', + 'The kernel development community', 'manual'), + ('filesystems/index', 'filesystems.tex', 'Linux Filesystems API', 'The kernel development community', 'manual'), ('gpu/index', 'gpu.tex', 'Linux GPU Driver Developer\'s Guide', 'The kernel development community', 'manual'), + ('input/index', 'linux-input.tex', 'The Linux input driver subsystem', + 'The kernel development community', 'manual'), + ('kernel-hacking/index', 'kernel-hacking.tex', 'Unreliable Guide To Hacking The Linux Kernel', + 'The kernel development community', 'manual'), ('media/index', 'media.tex', 'Linux Media Subsystem Documentation', 'The kernel development community', 'manual'), + ('networking/index', 'networking.tex', 'Linux Networking Documentation', + 'The kernel development community', 'manual'), + ('process/index', 'development-process.tex', 'Linux Kernel Development Documentation', + 'The kernel development community', 'manual'), ('security/index', 'security.tex', 'The kernel security subsystem manual', 'The kernel development community', 'manual'), + ('sh/index', 'sh.tex', 'SuperH architecture implementation manual', + 'The kernel development community', 'manual'), + ('sound/index', 'sound.tex', 'Linux Sound Subsystem Documentation', + 'The kernel development community', 'manual'), + ('userspace-api/index', 'userspace-api.tex', 'The Linux kernel user-space API guide', + 'The kernel development community', 'manual'), ] # The name of an image file (relative to this directory) to place at the top of diff --git a/Documentation/core-api/assoc_array.rst b/Documentation/core-api/assoc_array.rst index d83cfff9ea43..8231b915c939 100644 --- a/Documentation/core-api/assoc_array.rst +++ b/Documentation/core-api/assoc_array.rst @@ -10,7 +10,10 @@ properties: 1. Objects are opaque pointers. The implementation does not care where they point (if anywhere) or what they point to (if anything). -.. note:: Pointers to objects _must_ be zero in the least significant bit. + + .. note:: + + Pointers to objects _must_ be zero in the least significant bit. 2. Objects do not need to contain linkage blocks for use by the array. This permits an object to be located in multiple arrays simultaneously. diff --git a/Documentation/core-api/atomic_ops.rst b/Documentation/core-api/atomic_ops.rst index 55e43f1c80de..fce929144ccd 100644 --- a/Documentation/core-api/atomic_ops.rst +++ b/Documentation/core-api/atomic_ops.rst @@ -303,6 +303,11 @@ defined which accomplish this:: void smp_mb__before_atomic(void); void smp_mb__after_atomic(void); +Preceding a non-value-returning read-modify-write atomic operation with +smp_mb__before_atomic() and following it with smp_mb__after_atomic() +provides the same full ordering that is provided by value-returning +read-modify-write atomic operations. + For example, smp_mb__before_atomic() can be used like so:: obj->dead = 1; diff --git a/Documentation/core-api/index.rst b/Documentation/core-api/index.rst index 62abd36bfffb..0606be3a3111 100644 --- a/Documentation/core-api/index.rst +++ b/Documentation/core-api/index.rst @@ -19,6 +19,7 @@ Core utilities workqueue genericirq flexible-arrays + librs Interfaces for kernel debugging =============================== diff --git a/Documentation/core-api/librs.rst b/Documentation/core-api/librs.rst new file mode 100644 index 000000000000..6010f5bc5bf9 --- /dev/null +++ b/Documentation/core-api/librs.rst @@ -0,0 +1,212 @@ +========================================== +Reed-Solomon Library Programming Interface +========================================== + +:Author: Thomas Gleixner + +Introduction +============ + +The generic Reed-Solomon Library provides encoding, decoding and error +correction functions. + +Reed-Solomon codes are used in communication and storage applications to +ensure data integrity. + +This documentation is provided for developers who want to utilize the +functions provided by the library. + +Known Bugs And Assumptions +========================== + +None. + +Usage +===== + +This chapter provides examples of how to use the library. + +Initializing +------------ + +The init function init_rs returns a pointer to an rs decoder structure, +which holds the necessary information for encoding, decoding and error +correction with the given polynomial. It either uses an existing +matching decoder or creates a new one. On creation all the lookup tables +for fast en/decoding are created. The function may take a while, so make +sure not to call it in critical code paths. + +:: + + /* the Reed Solomon control structure */ + static struct rs_control *rs_decoder; + + /* Symbolsize is 10 (bits) + * Primitive polynomial is x^10+x^3+1 + * first consecutive root is 0 + * primitive element to generate roots = 1 + * generator polynomial degree (number of roots) = 6 + */ + rs_decoder = init_rs (10, 0x409, 0, 1, 6); + + +Encoding +-------- + +The encoder calculates the Reed-Solomon code over the given data length +and stores the result in the parity buffer. Note that the parity buffer +must be initialized before calling the encoder. + +The expanded data can be inverted on the fly by providing a non-zero +inversion mask. The expanded data is XOR'ed with the mask. This is used +e.g. for FLASH ECC, where the all 0xFF is inverted to an all 0x00. The +Reed-Solomon code for all 0x00 is all 0x00. The code is inverted before +storing to FLASH so it is 0xFF too. This prevents that reading from an +erased FLASH results in ECC errors. + +The databytes are expanded to the given symbol size on the fly. There is +no support for encoding continuous bitstreams with a symbol size != 8 at +the moment. If it is necessary it should be not a big deal to implement +such functionality. + +:: + + /* Parity buffer. Size = number of roots */ + uint16_t par[6]; + /* Initialize the parity buffer */ + memset(par, 0, sizeof(par)); + /* Encode 512 byte in data8. Store parity in buffer par */ + encode_rs8 (rs_decoder, data8, 512, par, 0); + + +Decoding +-------- + +The decoder calculates the syndrome over the given data length and the +received parity symbols and corrects errors in the data. + +If a syndrome is available from a hardware decoder then the syndrome +calculation is skipped. + +The correction of the data buffer can be suppressed by providing a +correction pattern buffer and an error location buffer to the decoder. +The decoder stores the calculated error location and the correction +bitmask in the given buffers. This is useful for hardware decoders which +use a weird bit ordering scheme. + +The databytes are expanded to the given symbol size on the fly. There is +no support for decoding continuous bitstreams with a symbolsize != 8 at +the moment. If it is necessary it should be not a big deal to implement +such functionality. + +Decoding with syndrome calculation, direct data correction +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + /* Parity buffer. Size = number of roots */ + uint16_t par[6]; + uint8_t data[512]; + int numerr; + /* Receive data */ + ..... + /* Receive parity */ + ..... + /* Decode 512 byte in data8.*/ + numerr = decode_rs8 (rs_decoder, data8, par, 512, NULL, 0, NULL, 0, NULL); + + +Decoding with syndrome given by hardware decoder, direct data correction +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + /* Parity buffer. Size = number of roots */ + uint16_t par[6], syn[6]; + uint8_t data[512]; + int numerr; + /* Receive data */ + ..... + /* Receive parity */ + ..... + /* Get syndrome from hardware decoder */ + ..... + /* Decode 512 byte in data8.*/ + numerr = decode_rs8 (rs_decoder, data8, par, 512, syn, 0, NULL, 0, NULL); + + +Decoding with syndrome given by hardware decoder, no direct data correction. +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Note: It's not necessary to give data and received parity to the +decoder. + +:: + + /* Parity buffer. Size = number of roots */ + uint16_t par[6], syn[6], corr[8]; + uint8_t data[512]; + int numerr, errpos[8]; + /* Receive data */ + ..... + /* Receive parity */ + ..... + /* Get syndrome from hardware decoder */ + ..... + /* Decode 512 byte in data8.*/ + numerr = decode_rs8 (rs_decoder, NULL, NULL, 512, syn, 0, errpos, 0, corr); + for (i = 0; i < numerr; i++) { + do_error_correction_in_your_buffer(errpos[i], corr[i]); + } + + +Cleanup +------- + +The function free_rs frees the allocated resources, if the caller is +the last user of the decoder. + +:: + + /* Release resources */ + free_rs(rs_decoder); + + +Structures +========== + +This chapter contains the autogenerated documentation of the structures +which are used in the Reed-Solomon Library and are relevant for a +developer. + +.. kernel-doc:: include/linux/rslib.h + :internal: + +Public Functions Provided +========================= + +This chapter contains the autogenerated documentation of the +Reed-Solomon functions which are exported. + +.. kernel-doc:: lib/reed_solomon/reed_solomon.c + :export: + +Credits +======= + +The library code for encoding and decoding was written by Phil Karn. + +:: + + Copyright 2002, Phil Karn, KA9Q + May be used under the terms of the GNU General Public License (GPL) + + +The wrapper functions and interfaces are written by Thomas Gleixner. + +Many users have provided bugfixes, improvements and helping hands for +testing. Thanks a lot. + +The following people have contributed to this document: + +Thomas Gleixner\ tglx@linutronix.de diff --git a/Documentation/cpu-freq/intel-pstate.txt b/Documentation/cpu-freq/intel-pstate.txt deleted file mode 100644 index 3fdcdfd968ba..000000000000 --- a/Documentation/cpu-freq/intel-pstate.txt +++ /dev/null @@ -1,281 +0,0 @@ -Intel P-State driver --------------------- - -This driver provides an interface to control the P-State selection for the -SandyBridge+ Intel processors. - -The following document explains P-States: -http://events.linuxfoundation.org/sites/events/files/slides/LinuxConEurope_2015.pdf -As stated in the document, P-State doesn’t exactly mean a frequency. However, for -the sake of the relationship with cpufreq, P-State and frequency are used -interchangeably. - -Understanding the cpufreq core governors and policies are important before -discussing more details about the Intel P-State driver. Based on what callbacks -a cpufreq driver provides to the cpufreq core, it can support two types of -drivers: -- with target_index() callback: In this mode, the drivers using cpufreq core -simply provide the minimum and maximum frequency limits and an additional -interface target_index() to set the current frequency. The cpufreq subsystem -has a number of scaling governors ("performance", "powersave", "ondemand", -etc.). Depending on which governor is in use, cpufreq core will call for -transitions to a specific frequency using target_index() callback. -- setpolicy() callback: In this mode, drivers do not provide target_index() -callback, so cpufreq core can't request a transition to a specific frequency. -The driver provides minimum and maximum frequency limits and callbacks to set a -policy. The policy in cpufreq sysfs is referred to as the "scaling governor". -The cpufreq core can request the driver to operate in any of the two policies: -"performance" and "powersave". The driver decides which frequency to use based -on the above policy selection considering minimum and maximum frequency limits. - -The Intel P-State driver falls under the latter category, which implements the -setpolicy() callback. This driver decides what P-State to use based on the -requested policy from the cpufreq core. If the processor is capable of -selecting its next P-State internally, then the driver will offload this -responsibility to the processor (aka HWP: Hardware P-States). If not, the -driver implements algorithms to select the next P-State. - -Since these policies are implemented in the driver, they are not same as the -cpufreq scaling governors implementation, even if they have the same name in -the cpufreq sysfs (scaling_governors). For example the "performance" policy is -similar to cpufreq’s "performance" governor, but "powersave" is completely -different than the cpufreq "powersave" governor. The strategy here is similar -to cpufreq "ondemand", where the requested P-State is related to the system load. - -Sysfs Interface - -In addition to the frequency-controlling interfaces provided by the cpufreq -core, the driver provides its own sysfs files to control the P-State selection. -These files have been added to /sys/devices/system/cpu/intel_pstate/. -Any changes made to these files are applicable to all CPUs (even in a -multi-package system, Refer to later section on placing "Per-CPU limits"). - - max_perf_pct: Limits the maximum P-State that will be requested by - the driver. It states it as a percentage of the available performance. The - available (P-State) performance may be reduced by the no_turbo - setting described below. - - min_perf_pct: Limits the minimum P-State that will be requested by - the driver. It states it as a percentage of the max (non-turbo) - performance level. - - no_turbo: Limits the driver to selecting P-State below the turbo - frequency range. - - turbo_pct: Displays the percentage of the total performance that - is supported by hardware that is in the turbo range. This number - is independent of whether turbo has been disabled or not. - - num_pstates: Displays the number of P-States that are supported - by hardware. This number is independent of whether turbo has - been disabled or not. - -For example, if a system has these parameters: - Max 1 core turbo ratio: 0x21 (Max 1 core ratio is the maximum P-State) - Max non turbo ratio: 0x17 - Minimum ratio : 0x08 (Here the ratio is called max efficiency ratio) - -Sysfs will show : - max_perf_pct:100, which corresponds to 1 core ratio - min_perf_pct:24, max_efficiency_ratio / max 1 Core ratio - no_turbo:0, turbo is not disabled - num_pstates:26 = (max 1 Core ratio - Max Efficiency Ratio + 1) - turbo_pct:39 = (max 1 core ratio - max non turbo ratio) / num_pstates - -Refer to "Intel® 64 and IA-32 Architectures Software Developer’s Manual -Volume 3: System Programming Guide" to understand ratios. - -There is one more sysfs attribute in /sys/devices/system/cpu/intel_pstate/ -that can be used for controlling the operation mode of the driver: - - status: Three settings are possible: - "off" - The driver is not in use at this time. - "active" - The driver works as a P-state governor (default). - "passive" - The driver works as a regular cpufreq one and collaborates - with the generic cpufreq governors (it sets P-states as - requested by those governors). - The current setting is returned by reads from this attribute. Writing one - of the above strings to it changes the operation mode as indicated by that - string, if possible. If HW-managed P-states (HWP) are enabled, it is not - possible to change the driver's operation mode and attempts to write to - this attribute will fail. - -cpufreq sysfs for Intel P-State - -Since this driver registers with cpufreq, cpufreq sysfs is also presented. -There are some important differences, which need to be considered. - -scaling_cur_freq: This displays the real frequency which was used during -the last sample period instead of what is requested. Some other cpufreq driver, -like acpi-cpufreq, displays what is requested (Some changes are on the -way to fix this for acpi-cpufreq driver). The same is true for frequencies -displayed at /proc/cpuinfo. - -scaling_governor: This displays current active policy. Since each CPU has a -cpufreq sysfs, it is possible to set a scaling governor to each CPU. But this -is not possible with Intel P-States, as there is one common policy for all -CPUs. Here, the last requested policy will be applicable to all CPUs. It is -suggested that one use the cpupower utility to change policy to all CPUs at the -same time. - -scaling_setspeed: This attribute can never be used with Intel P-State. - -scaling_max_freq/scaling_min_freq: This interface can be used similarly to -the max_perf_pct/min_perf_pct of Intel P-State sysfs. However since frequencies -are converted to nearest possible P-State, this is prone to rounding errors. -This method is not preferred to limit performance. - -affected_cpus: Not used -related_cpus: Not used - -For contemporary Intel processors, the frequency is controlled by the -processor itself and the P-State exposed to software is related to -performance levels. The idea that frequency can be set to a single -frequency is fictional for Intel Core processors. Even if the scaling -driver selects a single P-State, the actual frequency the processor -will run at is selected by the processor itself. - -Per-CPU limits - -The kernel command line option "intel_pstate=per_cpu_perf_limits" forces -the intel_pstate driver to use per-CPU performance limits. When it is set, -the sysfs control interface described above is subject to limitations. -- The following controls are not available for both read and write - /sys/devices/system/cpu/intel_pstate/max_perf_pct - /sys/devices/system/cpu/intel_pstate/min_perf_pct -- The following controls can be used to set performance limits, as far as the -architecture of the processor permits: - /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq - /sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq - /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor -- User can still observe turbo percent and number of P-States from - /sys/devices/system/cpu/intel_pstate/turbo_pct - /sys/devices/system/cpu/intel_pstate/num_pstates -- User can read write system wide turbo status - /sys/devices/system/cpu/no_turbo - -Support of energy performance hints -It is possible to provide hints to the HWP algorithms in the processor -to be more performance centric to more energy centric. When the driver -is using HWP, two additional cpufreq sysfs attributes are presented for -each logical CPU. -These attributes are: - - energy_performance_available_preferences - - energy_performance_preference - -To get list of supported hints: -$ cat energy_performance_available_preferences - default performance balance_performance balance_power power - -The current preference can be read or changed via cpufreq sysfs -attribute "energy_performance_preference". Reading from this attribute -will display current effective setting. User can write any of the valid -preference string to this attribute. User can always restore to power-on -default by writing "default". - -Since threads can migrate to different CPUs, this is possible that the -new CPU may have different energy performance preference than the previous -one. To avoid such issues, either threads can be pinned to specific CPUs -or set the same energy performance preference value to all CPUs. - -Tuning Intel P-State driver - -When the performance can be tuned using PID (Proportional Integral -Derivative) controller, debugfs files are provided for adjusting performance. -They are presented under: -/sys/kernel/debug/pstate_snb/ - -The PID tunable parameters are: - deadband - d_gain_pct - i_gain_pct - p_gain_pct - sample_rate_ms - setpoint - -To adjust these parameters, some understanding of driver implementation is -necessary. There are some tweeks described here, but be very careful. Adjusting -them requires expert level understanding of power and performance relationship. -These limits are only useful when the "powersave" policy is active. - --To make the system more responsive to load changes, sample_rate_ms can -be adjusted (current default is 10ms). --To make the system use higher performance, even if the load is lower, setpoint -can be adjusted to a lower number. This will also lead to faster ramp up time -to reach the maximum P-State. -If there are no derivative and integral coefficients, The next P-State will be -equal to: - current P-State - ((setpoint - current cpu load) * p_gain_pct) - -For example, if the current PID parameters are (Which are defaults for the core -processors like SandyBridge): - deadband = 0 - d_gain_pct = 0 - i_gain_pct = 0 - p_gain_pct = 20 - sample_rate_ms = 10 - setpoint = 97 - -If the current P-State = 0x08 and current load = 100, this will result in the -next P-State = 0x08 - ((97 - 100) * 0.2) = 8.6 (rounded to 9). Here the P-State -goes up by only 1. If during next sample interval the current load doesn't -change and still 100, then P-State goes up by one again. This process will -continue as long as the load is more than the setpoint until the maximum P-State -is reached. - -For the same load at setpoint = 60, this will result in the next P-State -= 0x08 - ((60 - 100) * 0.2) = 16 -So by changing the setpoint from 97 to 60, there is an increase of the -next P-State from 9 to 16. So this will make processor execute at higher -P-State for the same CPU load. If the load continues to be more than the -setpoint during next sample intervals, then P-State will go up again till the -maximum P-State is reached. But the ramp up time to reach the maximum P-State -will be much faster when the setpoint is 60 compared to 97. - -Debugging Intel P-State driver - -Event tracing -To debug P-State transition, the Linux event tracing interface can be used. -There are two specific events, which can be enabled (Provided the kernel -configs related to event tracing are enabled). - -# cd /sys/kernel/debug/tracing/ -# echo 1 > events/power/pstate_sample/enable -# echo 1 > events/power/cpu_frequency/enable -# cat trace -gnome-terminal--4510 [001] ..s. 1177.680733: pstate_sample: core_busy=107 - scaled=94 from=26 to=26 mperf=1143818 aperf=1230607 tsc=29838618 - freq=2474476 -cat-5235 [002] ..s. 1177.681723: cpu_frequency: state=2900000 cpu_id=2 - - -Using ftrace - -If function level tracing is required, the Linux ftrace interface can be used. -For example if we want to check how often a function to set a P-State is -called, we can set ftrace filter to intel_pstate_set_pstate. - -# cd /sys/kernel/debug/tracing/ -# cat available_filter_functions | grep -i pstate -intel_pstate_set_pstate -intel_pstate_cpu_init -... - -# echo intel_pstate_set_pstate > set_ftrace_filter -# echo function > current_tracer -# cat trace | head -15 -# tracer: function -# -# entries-in-buffer/entries-written: 80/80 #P:4 -# -# _-----=> irqs-off -# / _----=> need-resched -# | / _---=> hardirq/softirq -# || / _--=> preempt-depth -# ||| / delay -# TASK-PID CPU# |||| TIMESTAMP FUNCTION -# | | | |||| | | - Xorg-3129 [000] ..s. 2537.644844: intel_pstate_set_pstate <-intel_pstate_timer_func - gnome-terminal--4510 [002] ..s. 2537.649844: intel_pstate_set_pstate <-intel_pstate_timer_func - gnome-shell-3409 [001] ..s. 2537.650850: intel_pstate_set_pstate <-intel_pstate_timer_func - <idle>-0 [000] ..s. 2537.654843: intel_pstate_set_pstate <-intel_pstate_timer_func diff --git a/Documentation/crypto/api-samples.rst b/Documentation/crypto/api-samples.rst index d021fd96a76d..2531948db89f 100644 --- a/Documentation/crypto/api-samples.rst +++ b/Documentation/crypto/api-samples.rst @@ -155,9 +155,9 @@ Code Example For Use of Operational State Memory With SHASH char ctx[]; }; - static struct sdesc init_sdesc(struct crypto_shash *alg) + static struct sdesc *init_sdesc(struct crypto_shash *alg) { - struct sdesc sdesc; + struct sdesc *sdesc; int size; size = sizeof(struct shash_desc) + crypto_shash_descsize(alg); @@ -169,15 +169,16 @@ Code Example For Use of Operational State Memory With SHASH return sdesc; } - static int calc_hash(struct crypto_shashalg, - const unsigned chardata, unsigned int datalen, - unsigned chardigest) { - struct sdesc sdesc; + static int calc_hash(struct crypto_shash *alg, + const unsigned char *data, unsigned int datalen, + unsigned char *digest) + { + struct sdesc *sdesc; int ret; sdesc = init_sdesc(alg); if (IS_ERR(sdesc)) { - pr_info("trusted_key: can't alloc %s\n", hash_alg); + pr_info("can't alloc sdesc\n"); return PTR_ERR(sdesc); } @@ -186,6 +187,23 @@ Code Example For Use of Operational State Memory With SHASH return ret; } + static int test_hash(const unsigned char *data, unsigned int datalen, + unsigned char *digest) + { + struct crypto_shash *alg; + char *hash_alg_name = "sha1-padlock-nano"; + int ret; + + alg = crypto_alloc_shash(hash_alg_name, CRYPTO_ALG_TYPE_SHASH, 0); + if (IS_ERR(alg)) { + pr_info("can't alloc alg %s\n", hash_alg_name); + return PTR_ERR(alg); + } + ret = calc_hash(alg, data, datalen, digest); + crypto_free_shash(alg); + return ret; + } + Code Example For Random Number Generator Usage ---------------------------------------------- @@ -195,8 +213,8 @@ Code Example For Random Number Generator Usage static int get_random_numbers(u8 *buf, unsigned int len) { - struct crypto_rngrng = NULL; - chardrbg = "drbg_nopr_sha256"; /* Hash DRBG with SHA-256, no PR */ + struct crypto_rng *rng = NULL; + char *drbg = "drbg_nopr_sha256"; /* Hash DRBG with SHA-256, no PR */ int ret; if (!buf || !len) { @@ -207,7 +225,7 @@ Code Example For Random Number Generator Usage rng = crypto_alloc_rng(drbg, 0, 0); if (IS_ERR(rng)) { pr_debug("could not allocate RNG handle for %s\n", drbg); - return -PTR_ERR(rng); + return PTR_ERR(rng); } ret = crypto_rng_get_bytes(rng, buf, len); diff --git a/Documentation/crypto/asymmetric-keys.txt b/Documentation/crypto/asymmetric-keys.txt index 5ad6480e3fb9..b82b6ad48488 100644 --- a/Documentation/crypto/asymmetric-keys.txt +++ b/Documentation/crypto/asymmetric-keys.txt @@ -265,7 +265,7 @@ mandatory: The caller passes a pointer to the following struct with all of the fields cleared, except for data, datalen and quotalen [see - Documentation/security/keys.txt]. + Documentation/security/keys/core.rst]. struct key_preparsed_payload { char *description; diff --git a/Documentation/crypto/conf.py b/Documentation/crypto/conf.py new file mode 100644 index 000000000000..4335d251ddf3 --- /dev/null +++ b/Documentation/crypto/conf.py @@ -0,0 +1,10 @@ +# -*- coding: utf-8; mode: python -*- + +project = 'Linux Kernel Crypto API' + +tags.add("subproject") + +latex_documents = [ + ('index', 'crypto-api.tex', 'Linux Kernel Crypto API manual', + 'The kernel development community', 'manual'), +] diff --git a/Documentation/crypto/userspace-if.rst b/Documentation/crypto/userspace-if.rst index de5a72e32bc9..ff86befa61e0 100644 --- a/Documentation/crypto/userspace-if.rst +++ b/Documentation/crypto/userspace-if.rst @@ -327,7 +327,7 @@ boundary. Non-aligned data can be used as well, but may require more operations of the kernel which would defeat the speed gains obtained from the zero-copy interface. -The system-interent limit for the size of one zero-copy operation is 16 +The system-inherent limit for the size of one zero-copy operation is 16 pages. If more data is to be sent to AF_ALG, user space must slice the input into segments with a maximum size of 16 pages. diff --git a/Documentation/dev-tools/index.rst b/Documentation/dev-tools/index.rst index 07d881147ef3..4ac991dbddb7 100644 --- a/Documentation/dev-tools/index.rst +++ b/Documentation/dev-tools/index.rst @@ -23,6 +23,7 @@ whole; patches welcome! kmemleak kmemcheck gdb-kernel-debugging + kgdb .. only:: subproject and html diff --git a/Documentation/dev-tools/kgdb.rst b/Documentation/dev-tools/kgdb.rst new file mode 100644 index 000000000000..75273203a35a --- /dev/null +++ b/Documentation/dev-tools/kgdb.rst @@ -0,0 +1,907 @@ +================================================= +Using kgdb, kdb and the kernel debugger internals +================================================= + +:Author: Jason Wessel + +Introduction +============ + +The kernel has two different debugger front ends (kdb and kgdb) which +interface to the debug core. It is possible to use either of the +debugger front ends and dynamically transition between them if you +configure the kernel properly at compile and runtime. + +Kdb is simplistic shell-style interface which you can use on a system +console with a keyboard or serial console. You can use it to inspect +memory, registers, process lists, dmesg, and even set breakpoints to +stop in a certain location. Kdb is not a source level debugger, although +you can set breakpoints and execute some basic kernel run control. Kdb +is mainly aimed at doing some analysis to aid in development or +diagnosing kernel problems. You can access some symbols by name in +kernel built-ins or in kernel modules if the code was built with +``CONFIG_KALLSYMS``. + +Kgdb is intended to be used as a source level debugger for the Linux +kernel. It is used along with gdb to debug a Linux kernel. The +expectation is that gdb can be used to "break in" to the kernel to +inspect memory, variables and look through call stack information +similar to the way an application developer would use gdb to debug an +application. It is possible to place breakpoints in kernel code and +perform some limited execution stepping. + +Two machines are required for using kgdb. One of these machines is a +development machine and the other is the target machine. The kernel to +be debugged runs on the target machine. The development machine runs an +instance of gdb against the vmlinux file which contains the symbols (not +a boot image such as bzImage, zImage, uImage...). In gdb the developer +specifies the connection parameters and connects to kgdb. The type of +connection a developer makes with gdb depends on the availability of +kgdb I/O modules compiled as built-ins or loadable kernel modules in the +test machine's kernel. + +Compiling a kernel +================== + +- In order to enable compilation of kdb, you must first enable kgdb. + +- The kgdb test compile options are described in the kgdb test suite + chapter. + +Kernel config options for kgdb +------------------------------ + +To enable ``CONFIG_KGDB`` you should look under +:menuselection:`Kernel hacking --> Kernel debugging` and select +:menuselection:`KGDB: kernel debugger`. + +While it is not a hard requirement that you have symbols in your vmlinux +file, gdb tends not to be very useful without the symbolic data, so you +will want to turn on ``CONFIG_DEBUG_INFO`` which is called +:menuselection:`Compile the kernel with debug info` in the config menu. + +It is advised, but not required, that you turn on the +``CONFIG_FRAME_POINTER`` kernel option which is called :menuselection:`Compile +the kernel with frame pointers` in the config menu. This option inserts code +to into the compiled executable which saves the frame information in +registers or on the stack at different points which allows a debugger +such as gdb to more accurately construct stack back traces while +debugging the kernel. + +If the architecture that you are using supports the kernel option +``CONFIG_STRICT_KERNEL_RWX``, you should consider turning it off. This +option will prevent the use of software breakpoints because it marks +certain regions of the kernel's memory space as read-only. If kgdb +supports it for the architecture you are using, you can use hardware +breakpoints if you desire to run with the ``CONFIG_STRICT_KERNEL_RWX`` +option turned on, else you need to turn off this option. + +Next you should choose one of more I/O drivers to interconnect debugging +host and debugged target. Early boot debugging requires a KGDB I/O +driver that supports early debugging and the driver must be built into +the kernel directly. Kgdb I/O driver configuration takes place via +kernel or module parameters which you can learn more about in the in the +section that describes the parameter kgdboc. + +Here is an example set of ``.config`` symbols to enable or disable for kgdb:: + + # CONFIG_STRICT_KERNEL_RWX is not set + CONFIG_FRAME_POINTER=y + CONFIG_KGDB=y + CONFIG_KGDB_SERIAL_CONSOLE=y + +Kernel config options for kdb +----------------------------- + +Kdb is quite a bit more complex than the simple gdbstub sitting on top +of the kernel's debug core. Kdb must implement a shell, and also adds +some helper functions in other parts of the kernel, responsible for +printing out interesting data such as what you would see if you ran +``lsmod``, or ``ps``. In order to build kdb into the kernel you follow the +same steps as you would for kgdb. + +The main config option for kdb is ``CONFIG_KGDB_KDB`` which is called +:menuselection:`KGDB_KDB: include kdb frontend for kgdb` in the config menu. +In theory you would have already also selected an I/O driver such as the +``CONFIG_KGDB_SERIAL_CONSOLE`` interface if you plan on using kdb on a +serial port, when you were configuring kgdb. + +If you want to use a PS/2-style keyboard with kdb, you would select +``CONFIG_KDB_KEYBOARD`` which is called :menuselection:`KGDB_KDB: keyboard as +input device` in the config menu. The ``CONFIG_KDB_KEYBOARD`` option is not +used for anything in the gdb interface to kgdb. The ``CONFIG_KDB_KEYBOARD`` +option only works with kdb. + +Here is an example set of ``.config`` symbols to enable/disable kdb:: + + # CONFIG_STRICT_KERNEL_RWX is not set + CONFIG_FRAME_POINTER=y + CONFIG_KGDB=y + CONFIG_KGDB_SERIAL_CONSOLE=y + CONFIG_KGDB_KDB=y + CONFIG_KDB_KEYBOARD=y + +Kernel Debugger Boot Arguments +============================== + +This section describes the various runtime kernel parameters that affect +the configuration of the kernel debugger. The following chapter covers +using kdb and kgdb as well as providing some examples of the +configuration parameters. + +Kernel parameter: kgdboc +------------------------ + +The kgdboc driver was originally an abbreviation meant to stand for +"kgdb over console". Today it is the primary mechanism to configure how +to communicate from gdb to kgdb as well as the devices you want to use +to interact with the kdb shell. + +For kgdb/gdb, kgdboc is designed to work with a single serial port. It +is intended to cover the circumstance where you want to use a serial +console as your primary console as well as using it to perform kernel +debugging. It is also possible to use kgdb on a serial port which is not +designated as a system console. Kgdboc may be configured as a kernel +built-in or a kernel loadable module. You can only make use of +``kgdbwait`` and early debugging if you build kgdboc into the kernel as +a built-in. + +Optionally you can elect to activate kms (Kernel Mode Setting) +integration. When you use kms with kgdboc and you have a video driver +that has atomic mode setting hooks, it is possible to enter the debugger +on the graphics console. When the kernel execution is resumed, the +previous graphics mode will be restored. This integration can serve as a +useful tool to aid in diagnosing crashes or doing analysis of memory +with kdb while allowing the full graphics console applications to run. + +kgdboc arguments +~~~~~~~~~~~~~~~~ + +Usage:: + + kgdboc=[kms][[,]kbd][[,]serial_device][,baud] + +The order listed above must be observed if you use any of the optional +configurations together. + +Abbreviations: + +- kms = Kernel Mode Setting + +- kbd = Keyboard + +You can configure kgdboc to use the keyboard, and/or a serial device +depending on if you are using kdb and/or kgdb, in one of the following +scenarios. The order listed above must be observed if you use any of the +optional configurations together. Using kms + only gdb is generally not +a useful combination. + +Using loadable module or built-in +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +1. As a kernel built-in: + + Use the kernel boot argument:: + + kgdboc=<tty-device>,[baud] + +2. As a kernel loadable module: + + Use the command:: + + modprobe kgdboc kgdboc=<tty-device>,[baud] + + Here are two examples of how you might format the kgdboc string. The + first is for an x86 target using the first serial port. The second + example is for the ARM Versatile AB using the second serial port. + + 1. ``kgdboc=ttyS0,115200`` + + 2. ``kgdboc=ttyAMA1,115200`` + +Configure kgdboc at runtime with sysfs +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +At run time you can enable or disable kgdboc by echoing a parameters +into the sysfs. Here are two examples: + +1. Enable kgdboc on ttyS0:: + + echo ttyS0 > /sys/module/kgdboc/parameters/kgdboc + +2. Disable kgdboc:: + + echo "" > /sys/module/kgdboc/parameters/kgdboc + +.. note:: + + You do not need to specify the baud if you are configuring the + console on tty which is already configured or open. + +More examples +^^^^^^^^^^^^^ + +You can configure kgdboc to use the keyboard, and/or a serial device +depending on if you are using kdb and/or kgdb, in one of the following +scenarios. + +1. kdb and kgdb over only a serial port:: + + kgdboc=<serial_device>[,baud] + + Example:: + + kgdboc=ttyS0,115200 + +2. kdb and kgdb with keyboard and a serial port:: + + kgdboc=kbd,<serial_device>[,baud] + + Example:: + + kgdboc=kbd,ttyS0,115200 + +3. kdb with a keyboard:: + + kgdboc=kbd + +4. kdb with kernel mode setting:: + + kgdboc=kms,kbd + +5. kdb with kernel mode setting and kgdb over a serial port:: + + kgdboc=kms,kbd,ttyS0,115200 + +.. note:: + + Kgdboc does not support interrupting the target via the gdb remote + protocol. You must manually send a :kbd:`SysRq-G` unless you have a proxy + that splits console output to a terminal program. A console proxy has a + separate TCP port for the debugger and a separate TCP port for the + "human" console. The proxy can take care of sending the :kbd:`SysRq-G` + for you. + +When using kgdboc with no debugger proxy, you can end up connecting the +debugger at one of two entry points. If an exception occurs after you +have loaded kgdboc, a message should print on the console stating it is +waiting for the debugger. In this case you disconnect your terminal +program and then connect the debugger in its place. If you want to +interrupt the target system and forcibly enter a debug session you have +to issue a :kbd:`Sysrq` sequence and then type the letter :kbd:`g`. Then you +disconnect the terminal session and connect gdb. Your options if you +don't like this are to hack gdb to send the :kbd:`SysRq-G` for you as well as +on the initial connect, or to use a debugger proxy that allows an +unmodified gdb to do the debugging. + +Kernel parameter: ``kgdbwait`` +------------------------------ + +The Kernel command line option ``kgdbwait`` makes kgdb wait for a +debugger connection during booting of a kernel. You can only use this +option if you compiled a kgdb I/O driver into the kernel and you +specified the I/O driver configuration as a kernel command line option. +The kgdbwait parameter should always follow the configuration parameter +for the kgdb I/O driver in the kernel command line else the I/O driver +will not be configured prior to asking the kernel to use it to wait. + +The kernel will stop and wait as early as the I/O driver and +architecture allows when you use this option. If you build the kgdb I/O +driver as a loadable kernel module kgdbwait will not do anything. + +Kernel parameter: ``kgdbcon`` +----------------------------- + +The ``kgdbcon`` feature allows you to see :c:func:`printk` messages inside gdb +while gdb is connected to the kernel. Kdb does not make use of the kgdbcon +feature. + +Kgdb supports using the gdb serial protocol to send console messages to +the debugger when the debugger is connected and running. There are two +ways to activate this feature. + +1. Activate with the kernel command line option:: + + kgdbcon + +2. Use sysfs before configuring an I/O driver:: + + echo 1 > /sys/module/kgdb/parameters/kgdb_use_con + +.. note:: + + If you do this after you configure the kgdb I/O driver, the + setting will not take effect until the next point the I/O is + reconfigured. + +.. important:: + + You cannot use kgdboc + kgdbcon on a tty that is an + active system console. An example of incorrect usage is:: + + console=ttyS0,115200 kgdboc=ttyS0 kgdbcon + +It is possible to use this option with kgdboc on a tty that is not a +system console. + +Run time parameter: ``kgdbreboot`` +---------------------------------- + +The kgdbreboot feature allows you to change how the debugger deals with +the reboot notification. You have 3 choices for the behavior. The +default behavior is always set to 0. + +.. tabularcolumns:: |p{0.4cm}|p{11.5cm}|p{5.6cm}| + +.. flat-table:: + :widths: 1 10 8 + + * - 1 + - ``echo -1 > /sys/module/debug_core/parameters/kgdbreboot`` + - Ignore the reboot notification entirely. + + * - 2 + - ``echo 0 > /sys/module/debug_core/parameters/kgdbreboot`` + - Send the detach message to any attached debugger client. + + * - 3 + - ``echo 1 > /sys/module/debug_core/parameters/kgdbreboot`` + - Enter the debugger on reboot notify. + +Using kdb +========= + +Quick start for kdb on a serial port +------------------------------------ + +This is a quick example of how to use kdb. + +1. Configure kgdboc at boot using kernel parameters:: + + console=ttyS0,115200 kgdboc=ttyS0,115200 + + OR + + Configure kgdboc after the kernel has booted; assuming you are using + a serial port console:: + + echo ttyS0 > /sys/module/kgdboc/parameters/kgdboc + +2. Enter the kernel debugger manually or by waiting for an oops or + fault. There are several ways you can enter the kernel debugger + manually; all involve using the :kbd:`SysRq-G`, which means you must have + enabled ``CONFIG_MAGIC_SysRq=y`` in your kernel config. + + - When logged in as root or with a super user session you can run:: + + echo g > /proc/sysrq-trigger + + - Example using minicom 2.2 + + Press: :kbd:`CTRL-A` :kbd:`f` :kbd:`g` + + - When you have telneted to a terminal server that supports sending + a remote break + + Press: :kbd:`CTRL-]` + + Type in: ``send break`` + + Press: :kbd:`Enter` :kbd:`g` + +3. From the kdb prompt you can run the ``help`` command to see a complete + list of the commands that are available. + + Some useful commands in kdb include: + + =========== ================================================================= + ``lsmod`` Shows where kernel modules are loaded + ``ps`` Displays only the active processes + ``ps A`` Shows all the processes + ``summary`` Shows kernel version info and memory usage + ``bt`` Get a backtrace of the current process using :c:func:`dump_stack` + ``dmesg`` View the kernel syslog buffer + ``go`` Continue the system + =========== ================================================================= + +4. When you are done using kdb you need to consider rebooting the system + or using the ``go`` command to resuming normal kernel execution. If you + have paused the kernel for a lengthy period of time, applications + that rely on timely networking or anything to do with real wall clock + time could be adversely affected, so you should take this into + consideration when using the kernel debugger. + +Quick start for kdb using a keyboard connected console +------------------------------------------------------ + +This is a quick example of how to use kdb with a keyboard. + +1. Configure kgdboc at boot using kernel parameters:: + + kgdboc=kbd + + OR + + Configure kgdboc after the kernel has booted:: + + echo kbd > /sys/module/kgdboc/parameters/kgdboc + +2. Enter the kernel debugger manually or by waiting for an oops or + fault. There are several ways you can enter the kernel debugger + manually; all involve using the :kbd:`SysRq-G`, which means you must have + enabled ``CONFIG_MAGIC_SysRq=y`` in your kernel config. + + - When logged in as root or with a super user session you can run:: + + echo g > /proc/sysrq-trigger + + - Example using a laptop keyboard: + + Press and hold down: :kbd:`Alt` + + Press and hold down: :kbd:`Fn` + + Press and release the key with the label: :kbd:`SysRq` + + Release: :kbd:`Fn` + + Press and release: :kbd:`g` + + Release: :kbd:`Alt` + + - Example using a PS/2 101-key keyboard + + Press and hold down: :kbd:`Alt` + + Press and release the key with the label: :kbd:`SysRq` + + Press and release: :kbd:`g` + + Release: :kbd:`Alt` + +3. Now type in a kdb command such as ``help``, ``dmesg``, ``bt`` or ``go`` to + continue kernel execution. + +Using kgdb / gdb +================ + +In order to use kgdb you must activate it by passing configuration +information to one of the kgdb I/O drivers. If you do not pass any +configuration information kgdb will not do anything at all. Kgdb will +only actively hook up to the kernel trap hooks if a kgdb I/O driver is +loaded and configured. If you unconfigure a kgdb I/O driver, kgdb will +unregister all the kernel hook points. + +All kgdb I/O drivers can be reconfigured at run time, if +``CONFIG_SYSFS`` and ``CONFIG_MODULES`` are enabled, by echo'ing a new +config string to ``/sys/module/<driver>/parameter/<option>``. The driver +can be unconfigured by passing an empty string. You cannot change the +configuration while the debugger is attached. Make sure to detach the +debugger with the ``detach`` command prior to trying to unconfigure a +kgdb I/O driver. + +Connecting with gdb to a serial port +------------------------------------ + +1. Configure kgdboc + + Configure kgdboc at boot using kernel parameters:: + + kgdboc=ttyS0,115200 + + OR + + Configure kgdboc after the kernel has booted:: + + echo ttyS0 > /sys/module/kgdboc/parameters/kgdboc + +2. Stop kernel execution (break into the debugger) + + In order to connect to gdb via kgdboc, the kernel must first be + stopped. There are several ways to stop the kernel which include + using kgdbwait as a boot argument, via a :kbd:`SysRq-G`, or running the + kernel until it takes an exception where it waits for the debugger to + attach. + + - When logged in as root or with a super user session you can run:: + + echo g > /proc/sysrq-trigger + + - Example using minicom 2.2 + + Press: :kbd:`CTRL-A` :kbd:`f` :kbd:`g` + + - When you have telneted to a terminal server that supports sending + a remote break + + Press: :kbd:`CTRL-]` + + Type in: ``send break`` + + Press: :kbd:`Enter` :kbd:`g` + +3. Connect from gdb + + Example (using a directly connected port):: + + % gdb ./vmlinux + (gdb) set remotebaud 115200 + (gdb) target remote /dev/ttyS0 + + + Example (kgdb to a terminal server on TCP port 2012):: + + % gdb ./vmlinux + (gdb) target remote 192.168.2.2:2012 + + + Once connected, you can debug a kernel the way you would debug an + application program. + + If you are having problems connecting or something is going seriously + wrong while debugging, it will most often be the case that you want + to enable gdb to be verbose about its target communications. You do + this prior to issuing the ``target remote`` command by typing in:: + + set debug remote 1 + +Remember if you continue in gdb, and need to "break in" again, you need +to issue an other :kbd:`SysRq-G`. It is easy to create a simple entry point by +putting a breakpoint at ``sys_sync`` and then you can run ``sync`` from a +shell or script to break into the debugger. + +kgdb and kdb interoperability +============================= + +It is possible to transition between kdb and kgdb dynamically. The debug +core will remember which you used the last time and automatically start +in the same mode. + +Switching between kdb and kgdb +------------------------------ + +Switching from kgdb to kdb +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +There are two ways to switch from kgdb to kdb: you can use gdb to issue +a maintenance packet, or you can blindly type the command ``$3#33``. +Whenever the kernel debugger stops in kgdb mode it will print the +message ``KGDB or $3#33 for KDB``. It is important to note that you have +to type the sequence correctly in one pass. You cannot type a backspace +or delete because kgdb will interpret that as part of the debug stream. + +1. Change from kgdb to kdb by blindly typing:: + + $3#33 + +2. Change from kgdb to kdb with gdb:: + + maintenance packet 3 + + .. note:: + + Now you must kill gdb. Typically you press :kbd:`CTRL-Z` and issue + the command:: + + kill -9 % + +Change from kdb to kgdb +~~~~~~~~~~~~~~~~~~~~~~~ + +There are two ways you can change from kdb to kgdb. You can manually +enter kgdb mode by issuing the kgdb command from the kdb shell prompt, +or you can connect gdb while the kdb shell prompt is active. The kdb +shell looks for the typical first commands that gdb would issue with the +gdb remote protocol and if it sees one of those commands it +automatically changes into kgdb mode. + +1. From kdb issue the command:: + + kgdb + + Now disconnect your terminal program and connect gdb in its place + +2. At the kdb prompt, disconnect the terminal program and connect gdb in + its place. + +Running kdb commands from gdb +----------------------------- + +It is possible to run a limited set of kdb commands from gdb, using the +gdb monitor command. You don't want to execute any of the run control or +breakpoint operations, because it can disrupt the state of the kernel +debugger. You should be using gdb for breakpoints and run control +operations if you have gdb connected. The more useful commands to run +are things like lsmod, dmesg, ps or possibly some of the memory +information commands. To see all the kdb commands you can run +``monitor help``. + +Example:: + + (gdb) monitor ps + 1 idle process (state I) and + 27 sleeping system daemon (state M) processes suppressed, + use 'ps A' to see all. + Task Addr Pid Parent [*] cpu State Thread Command + + 0xc78291d0 1 0 0 0 S 0xc7829404 init + 0xc7954150 942 1 0 0 S 0xc7954384 dropbear + 0xc78789c0 944 1 0 0 S 0xc7878bf4 sh + (gdb) + +kgdb Test Suite +=============== + +When kgdb is enabled in the kernel config you can also elect to enable +the config parameter ``KGDB_TESTS``. Turning this on will enable a special +kgdb I/O module which is designed to test the kgdb internal functions. + +The kgdb tests are mainly intended for developers to test the kgdb +internals as well as a tool for developing a new kgdb architecture +specific implementation. These tests are not really for end users of the +Linux kernel. The primary source of documentation would be to look in +the ``drivers/misc/kgdbts.c`` file. + +The kgdb test suite can also be configured at compile time to run the +core set of tests by setting the kernel config parameter +``KGDB_TESTS_ON_BOOT``. This particular option is aimed at automated +regression testing and does not require modifying the kernel boot config +arguments. If this is turned on, the kgdb test suite can be disabled by +specifying ``kgdbts=`` as a kernel boot argument. + +Kernel Debugger Internals +========================= + +Architecture Specifics +---------------------- + +The kernel debugger is organized into a number of components: + +1. The debug core + + The debug core is found in ``kernel/debugger/debug_core.c``. It + contains: + + - A generic OS exception handler which includes sync'ing the + processors into a stopped state on an multi-CPU system. + + - The API to talk to the kgdb I/O drivers + + - The API to make calls to the arch-specific kgdb implementation + + - The logic to perform safe memory reads and writes to memory while + using the debugger + + - A full implementation for software breakpoints unless overridden + by the arch + + - The API to invoke either the kdb or kgdb frontend to the debug + core. + + - The structures and callback API for atomic kernel mode setting. + + .. note:: kgdboc is where the kms callbacks are invoked. + +2. kgdb arch-specific implementation + + This implementation is generally found in ``arch/*/kernel/kgdb.c``. As + an example, ``arch/x86/kernel/kgdb.c`` contains the specifics to + implement HW breakpoint as well as the initialization to dynamically + register and unregister for the trap handlers on this architecture. + The arch-specific portion implements: + + - contains an arch-specific trap catcher which invokes + :c:func:`kgdb_handle_exception` to start kgdb about doing its work + + - translation to and from gdb specific packet format to :c:type:`pt_regs` + + - Registration and unregistration of architecture specific trap + hooks + + - Any special exception handling and cleanup + + - NMI exception handling and cleanup + + - (optional) HW breakpoints + +3. gdbstub frontend (aka kgdb) + + The gdbstub is located in ``kernel/debug/gdbstub.c``. It contains: + + - All the logic to implement the gdb serial protocol + +4. kdb frontend + + The kdb debugger shell is broken down into a number of components. + The kdb core is located in kernel/debug/kdb. There are a number of + helper functions in some of the other kernel components to make it + possible for kdb to examine and report information about the kernel + without taking locks that could cause a kernel deadlock. The kdb core + contains implements the following functionality. + + - A simple shell + + - The kdb core command set + + - A registration API to register additional kdb shell commands. + + - A good example of a self-contained kdb module is the ``ftdump`` + command for dumping the ftrace buffer. See: + ``kernel/trace/trace_kdb.c`` + + - For an example of how to dynamically register a new kdb command + you can build the kdb_hello.ko kernel module from + ``samples/kdb/kdb_hello.c``. To build this example you can set + ``CONFIG_SAMPLES=y`` and ``CONFIG_SAMPLE_KDB=m`` in your kernel + config. Later run ``modprobe kdb_hello`` and the next time you + enter the kdb shell, you can run the ``hello`` command. + + - The implementation for :c:func:`kdb_printf` which emits messages directly + to I/O drivers, bypassing the kernel log. + + - SW / HW breakpoint management for the kdb shell + +5. kgdb I/O driver + + Each kgdb I/O driver has to provide an implementation for the + following: + + - configuration via built-in or module + + - dynamic configuration and kgdb hook registration calls + + - read and write character interface + + - A cleanup handler for unconfiguring from the kgdb core + + - (optional) Early debug methodology + + Any given kgdb I/O driver has to operate very closely with the + hardware and must do it in such a way that does not enable interrupts + or change other parts of the system context without completely + restoring them. The kgdb core will repeatedly "poll" a kgdb I/O + driver for characters when it needs input. The I/O driver is expected + to return immediately if there is no data available. Doing so allows + for the future possibility to touch watchdog hardware in such a way + as to have a target system not reset when these are enabled. + +If you are intent on adding kgdb architecture specific support for a new +architecture, the architecture should define ``HAVE_ARCH_KGDB`` in the +architecture specific Kconfig file. This will enable kgdb for the +architecture, and at that point you must create an architecture specific +kgdb implementation. + +There are a few flags which must be set on every architecture in their +``asm/kgdb.h`` file. These are: + +- ``NUMREGBYTES``: + The size in bytes of all of the registers, so that we + can ensure they will all fit into a packet. + +- ``BUFMAX``: + The size in bytes of the buffer GDB will read into. This must + be larger than NUMREGBYTES. + +- ``CACHE_FLUSH_IS_SAFE``: + Set to 1 if it is always safe to call + flush_cache_range or flush_icache_range. On some architectures, + these functions may not be safe to call on SMP since we keep other + CPUs in a holding pattern. + +There are also the following functions for the common backend, found in +``kernel/kgdb.c``, that must be supplied by the architecture-specific +backend unless marked as (optional), in which case a default function +maybe used if the architecture does not need to provide a specific +implementation. + +.. kernel-doc:: include/linux/kgdb.h + :internal: + +kgdboc internals +---------------- + +kgdboc and uarts +~~~~~~~~~~~~~~~~ + +The kgdboc driver is actually a very thin driver that relies on the +underlying low level to the hardware driver having "polling hooks" to +which the tty driver is attached. In the initial implementation of +kgdboc the serial_core was changed to expose a low level UART hook for +doing polled mode reading and writing of a single character while in an +atomic context. When kgdb makes an I/O request to the debugger, kgdboc +invokes a callback in the serial core which in turn uses the callback in +the UART driver. + +When using kgdboc with a UART, the UART driver must implement two +callbacks in the :c:type:`struct uart_ops <uart_ops>`. +Example from ``drivers/8250.c``:: + + + #ifdef CONFIG_CONSOLE_POLL + .poll_get_char = serial8250_get_poll_char, + .poll_put_char = serial8250_put_poll_char, + #endif + + +Any implementation specifics around creating a polling driver use the +``#ifdef CONFIG_CONSOLE_POLL``, as shown above. Keep in mind that +polling hooks have to be implemented in such a way that they can be +called from an atomic context and have to restore the state of the UART +chip on return such that the system can return to normal when the +debugger detaches. You need to be very careful with any kind of lock you +consider, because failing here is most likely going to mean pressing the +reset button. + +kgdboc and keyboards +~~~~~~~~~~~~~~~~~~~~~~~~ + +The kgdboc driver contains logic to configure communications with an +attached keyboard. The keyboard infrastructure is only compiled into the +kernel when ``CONFIG_KDB_KEYBOARD=y`` is set in the kernel configuration. + +The core polled keyboard driver driver for PS/2 type keyboards is in +``drivers/char/kdb_keyboard.c``. This driver is hooked into the debug core +when kgdboc populates the callback in the array called +:c:type:`kdb_poll_funcs[]`. The :c:func:`kdb_get_kbd_char` is the top-level +function which polls hardware for single character input. + +kgdboc and kms +~~~~~~~~~~~~~~~~~~ + +The kgdboc driver contains logic to request the graphics display to +switch to a text context when you are using ``kgdboc=kms,kbd``, provided +that you have a video driver which has a frame buffer console and atomic +kernel mode setting support. + +Every time the kernel debugger is entered it calls +:c:func:`kgdboc_pre_exp_handler` which in turn calls :c:func:`con_debug_enter` +in the virtual console layer. On resuming kernel execution, the kernel +debugger calls :c:func:`kgdboc_post_exp_handler` which in turn calls +:c:func:`con_debug_leave`. + +Any video driver that wants to be compatible with the kernel debugger +and the atomic kms callbacks must implement the ``mode_set_base_atomic``, +``fb_debug_enter`` and ``fb_debug_leave operations``. For the +``fb_debug_enter`` and ``fb_debug_leave`` the option exists to use the +generic drm fb helper functions or implement something custom for the +hardware. The following example shows the initialization of the +.mode_set_base_atomic operation in +drivers/gpu/drm/i915/intel_display.c:: + + + static const struct drm_crtc_helper_funcs intel_helper_funcs = { + [...] + .mode_set_base_atomic = intel_pipe_set_base_atomic, + [...] + }; + + +Here is an example of how the i915 driver initializes the +fb_debug_enter and fb_debug_leave functions to use the generic drm +helpers in ``drivers/gpu/drm/i915/intel_fb.c``:: + + + static struct fb_ops intelfb_ops = { + [...] + .fb_debug_enter = drm_fb_helper_debug_enter, + .fb_debug_leave = drm_fb_helper_debug_leave, + [...] + }; + + +Credits +======= + +The following people have contributed to this document: + +1. Amit Kale <amitkale@linsyssoft.com> + +2. Tom Rini <trini@kernel.crashing.org> + +In March 2008 this document was completely rewritten by: + +- Jason Wessel <jason.wessel@windriver.com> + +In Jan 2010 this document was updated to include kdb. + +- Jason Wessel <jason.wessel@windriver.com> diff --git a/Documentation/dev-tools/sparse.rst b/Documentation/dev-tools/sparse.rst index ffdcc97f6f5a..78aa00a604a0 100644 --- a/Documentation/dev-tools/sparse.rst +++ b/Documentation/dev-tools/sparse.rst @@ -103,9 +103,3 @@ have already built it. The optional make variable CF can be used to pass arguments to sparse. The build system passes -Wbitwise to sparse automatically. - -Checking RCU annotations -~~~~~~~~~~~~~~~~~~~~~~~~ - -RCU annotations are not checked by default. To enable RCU annotation -checks, include -DCONFIG_SPARSE_RCU_POINTER in your CF flags. diff --git a/Documentation/devicetree/bindings/arm/actions.txt b/Documentation/devicetree/bindings/arm/actions.txt new file mode 100644 index 000000000000..3bc7ea575564 --- /dev/null +++ b/Documentation/devicetree/bindings/arm/actions.txt @@ -0,0 +1,39 @@ +Actions Semi platforms device tree bindings +------------------------------------------- + + +S500 SoC +======== + +Required root node properties: + + - compatible : must contain "actions,s500" + + +Modules: + +Root node property compatible must contain, depending on module: + + - LeMaker Guitar: "lemaker,guitar" + + +Boards: + +Root node property compatible must contain, depending on board: + + - LeMaker Guitar Base Board rev. B: "lemaker,guitar-bb-rev-b", "lemaker,guitar" + + +S900 SoC +======== + +Required root node properties: + +- compatible : must contain "actions,s900" + + +Boards: + +Root node property compatible must contain, depending on board: + + - uCRobotics Bubblegum-96: "ucrobotics,bubblegum-96" diff --git a/Documentation/devicetree/bindings/arm/amlogic.txt b/Documentation/devicetree/bindings/arm/amlogic.txt index bfd5b558477d..0fff40a6330d 100644 --- a/Documentation/devicetree/bindings/arm/amlogic.txt +++ b/Documentation/devicetree/bindings/arm/amlogic.txt @@ -29,26 +29,35 @@ Boards with the Amlogic Meson GXM S912 SoC shall have the following properties: Required root node property: compatible: "amlogic,s912", "amlogic,meson-gxm"; -Board compatible values: +Board compatible values (alphabetically, grouped by SoC): + - "geniatech,atv1200" (Meson6) + - "minix,neo-x8" (Meson8) - - "tronfy,mxq" (Meson8b) + - "hardkernel,odroid-c1" (Meson8b) + - "tronfy,mxq" (Meson8b) + + - "amlogic,p200" (Meson gxbb) + - "amlogic,p201" (Meson gxbb) + - "friendlyarm,nanopi-k2" (Meson gxbb) + - "hardkernel,odroid-c2" (Meson gxbb) + - "nexbox,a95x" (Meson gxbb or Meson gxl s905x) - "tronsmart,vega-s95-pro", "tronsmart,vega-s95" (Meson gxbb) - "tronsmart,vega-s95-meta", "tronsmart,vega-s95" (Meson gxbb) - "tronsmart,vega-s95-telos", "tronsmart,vega-s95" (Meson gxbb) - - "hardkernel,odroid-c2" (Meson gxbb) - - "amlogic,p200" (Meson gxbb) - - "amlogic,p201" (Meson gxbb) - "wetek,hub" (Meson gxbb) - "wetek,play2" (Meson gxbb) + - "amlogic,p212" (Meson gxl s905x) + - "hwacom,amazetv" (Meson gxl s905x) - "khadas,vim" (Meson gxl s905x) + - "libretech,cc" (Meson gxl s905x) - "amlogic,p230" (Meson gxl s905d) - "amlogic,p231" (Meson gxl s905d) - - "hwacom,amazetv" (Meson gxl s905x) + - "amlogic,q200" (Meson gxm s912) - "amlogic,q201" (Meson gxm s912) - - "nexbox,a95x" (Meson gxbb or Meson gxl s905x) + - "kingnovel,r-box-pro" (Meson gxm S912) - "nexbox,a1" (Meson gxm s912) diff --git a/Documentation/devicetree/bindings/arm/atmel-at91.txt b/Documentation/devicetree/bindings/arm/atmel-at91.txt index 799af90dd75b..91cb8e4f2a4f 100644 --- a/Documentation/devicetree/bindings/arm/atmel-at91.txt +++ b/Documentation/devicetree/bindings/arm/atmel-at91.txt @@ -41,6 +41,36 @@ compatible: must be one of: - "atmel,sama5d43" - "atmel,sama5d44" + * "atmel,samv7" for MCUs using a Cortex-M7, shall be extended with the specific + SoC family: + o "atmel,sams70" shall be extended with the specific MCU compatible: + - "atmel,sams70j19" + - "atmel,sams70j20" + - "atmel,sams70j21" + - "atmel,sams70n19" + - "atmel,sams70n20" + - "atmel,sams70n21" + - "atmel,sams70q19" + - "atmel,sams70q20" + - "atmel,sams70q21" + o "atmel,samv70" shall be extended with the specific MCU compatible: + - "atmel,samv70j19" + - "atmel,samv70j20" + - "atmel,samv70n19" + - "atmel,samv70n20" + - "atmel,samv70q19" + - "atmel,samv70q20" + o "atmel,samv71" shall be extended with the specific MCU compatible: + - "atmel,samv71j19" + - "atmel,samv71j20" + - "atmel,samv71j21" + - "atmel,samv71n19" + - "atmel,samv71n20" + - "atmel,samv71n21" + - "atmel,samv71q19" + - "atmel,samv71q20" + - "atmel,samv71q21" + Chipid required properties: - compatible: Should be "atmel,sama5d2-chipid" - reg : Should contain registers location and length diff --git a/Documentation/devicetree/bindings/arm/bcm/brcm,stingray.txt b/Documentation/devicetree/bindings/arm/bcm/brcm,stingray.txt new file mode 100644 index 000000000000..23a02178dd44 --- /dev/null +++ b/Documentation/devicetree/bindings/arm/bcm/brcm,stingray.txt @@ -0,0 +1,12 @@ +Broadcom Stingray device tree bindings +------------------------------------------------ + +Boards with Stingray shall have the following properties: + +Required root node property: + +Stingray Combo SVK board +compatible = "brcm,bcm958742k", "brcm,stingray"; + +Stingray SST100 board +compatible = "brcm,bcm958742t", "brcm,stingray"; diff --git a/Documentation/devicetree/bindings/arm/ccn.txt b/Documentation/devicetree/bindings/arm/ccn.txt index b100d3847d88..29801456c9ee 100644 --- a/Documentation/devicetree/bindings/arm/ccn.txt +++ b/Documentation/devicetree/bindings/arm/ccn.txt @@ -3,6 +3,7 @@ Required properties: - compatible: (standard compatible string) should be one of: + "arm,ccn-502" "arm,ccn-504" "arm,ccn-508" diff --git a/Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt b/Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt new file mode 100644 index 000000000000..298291211ea4 --- /dev/null +++ b/Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt @@ -0,0 +1,49 @@ +* CoreSight CPU Debug Component: + +CoreSight CPU debug component are compliant with the ARMv8 architecture +reference manual (ARM DDI 0487A.k) Chapter 'Part H: External debug'. The +external debug module is mainly used for two modes: self-hosted debug and +external debug, and it can be accessed from mmio region from Coresight +and eventually the debug module connects with CPU for debugging. And the +debug module provides sample-based profiling extension, which can be used +to sample CPU program counter, secure state and exception level, etc; +usually every CPU has one dedicated debug module to be connected. + +Required properties: + +- compatible : should be "arm,coresight-cpu-debug"; supplemented with + "arm,primecell" since this driver is using the AMBA bus + interface. + +- reg : physical base address and length of the register set. + +- clocks : the clock associated to this component. + +- clock-names : the name of the clock referenced by the code. Since we are + using the AMBA framework, the name of the clock providing + the interconnect should be "apb_pclk" and the clock is + mandatory. The interface between the debug logic and the + processor core is clocked by the internal CPU clock, so it + is enabled with CPU clock by default. + +- cpu : the CPU phandle the debug module is affined to. When omitted + the module is considered to belong to CPU0. + +Optional properties: + +- power-domains: a phandle to the debug power domain. We use "power-domains" + binding to turn on the debug logic if it has own dedicated + power domain and if necessary to use "cpuidle.off=1" or + "nohlt" in the kernel command line or sysfs node to + constrain idle states to ensure registers in the CPU power + domain are accessible. + +Example: + + debug@f6590000 { + compatible = "arm,coresight-cpu-debug","arm,primecell"; + reg = <0 0xf6590000 0 0x1000>; + clocks = <&sys_ctrl HI6220_DAPB_CLK>; + clock-names = "apb_pclk"; + cpu = <&cpu0>; + }; diff --git a/Documentation/devicetree/bindings/arm/cpus.txt b/Documentation/devicetree/bindings/arm/cpus.txt index 1030f5f50207..ad1913bea8d7 100644 --- a/Documentation/devicetree/bindings/arm/cpus.txt +++ b/Documentation/devicetree/bindings/arm/cpus.txt @@ -193,6 +193,7 @@ nodes to be present and contain the properties described below. "spin-table" # On ARM 32-bit systems this property is optional and can be one of: + "actions,s500-smp" "allwinner,sun6i-a31" "allwinner,sun8i-a23" "arm,realview-smp" @@ -249,7 +250,7 @@ nodes to be present and contain the properties described below. Usage: Optional Value type: <u32> Definition: - # u32 value representing CPU capacity [3] in + # u32 value representing CPU capacity [4] in DMIPS/MHz, relative to highest capacity-dmips-mhz in the system. @@ -476,5 +477,5 @@ cpus { [2] arm/msm/qcom,kpss-acc.txt [3] ARM Linux kernel documentation - idle states bindings Documentation/devicetree/bindings/arm/idle-states.txt -[3] ARM Linux kernel documentation - cpu capacity bindings +[4] ARM Linux kernel documentation - cpu capacity bindings Documentation/devicetree/bindings/arm/cpu-capacity.txt diff --git a/Documentation/devicetree/bindings/arm/gemini.txt b/Documentation/devicetree/bindings/arm/gemini.txt index 0041eb031116..55bf7ce96c44 100644 --- a/Documentation/devicetree/bindings/arm/gemini.txt +++ b/Documentation/devicetree/bindings/arm/gemini.txt @@ -24,6 +24,19 @@ Required nodes: global control registers, with the compatible string "cortina,gemini-syscon", "syscon"; + Required properties on the syscon: + - reg: syscon register location and size. + - #clock-cells: should be set to <1> - the system controller is also a + clock provider. + - #reset-cells: should be set to <1> - the system controller is also a + reset line provider. + + The clock sources have shorthand defines in the include file: + <dt-bindings/clock/cortina,gemini-clock.h> + + The reset lines have shorthand defines in the include file: + <dt-bindings/reset/cortina,gemini-reset.h> + - timer: the soc bus node must have a timer node pointing to the SoC timer block, with the compatible string "cortina,gemini-timer" See: clocksource/cortina,gemini-timer.txt @@ -56,12 +69,15 @@ Example: syscon: syscon@40000000 { compatible = "cortina,gemini-syscon", "syscon"; reg = <0x40000000 0x1000>; + #clock-cells = <1>; + #reset-cells = <1>; }; uart0: serial@42000000 { compatible = "ns16550a"; reg = <0x42000000 0x100>; - clock-frequency = <48000000>; + resets = <&syscon GEMINI_RESET_UART>; + clocks = <&syscon GEMINI_CLK_UART>; interrupts = <18 IRQ_TYPE_LEVEL_HIGH>; reg-shift = <2>; }; @@ -73,12 +89,18 @@ Example: interrupts = <14 IRQ_TYPE_EDGE_FALLING>, /* Timer 1 */ <15 IRQ_TYPE_EDGE_FALLING>, /* Timer 2 */ <16 IRQ_TYPE_EDGE_FALLING>; /* Timer 3 */ + resets = <&syscon GEMINI_RESET_TIMER>; + /* APB clock or RTC clock */ + clocks = <&syscon GEMINI_CLK_APB>, + <&syscon GEMINI_CLK_RTC>; + clock-names = "PCLK", "EXTCLK"; syscon = <&syscon>; }; intcon: interrupt-controller@48000000 { compatible = "cortina,gemini-interrupt-controller"; reg = <0x48000000 0x1000>; + resets = <&syscon GEMINI_RESET_INTCON0>; interrupt-controller; #interrupt-cells = <2>; }; diff --git a/Documentation/devicetree/bindings/arm/hisilicon/hisilicon.txt b/Documentation/devicetree/bindings/arm/hisilicon/hisilicon.txt index 2e732152064b..7111fbc82a4e 100644 --- a/Documentation/devicetree/bindings/arm/hisilicon/hisilicon.txt +++ b/Documentation/devicetree/bindings/arm/hisilicon/hisilicon.txt @@ -4,6 +4,10 @@ Hi3660 SoC Required root node properties: - compatible = "hisilicon,hi3660"; +HiKey960 Board +Required root node properties: + - compatible = "hisilicon,hi3660-hikey960", "hisilicon,hi3660"; + Hi3798cv200 SoC Required root node properties: - compatible = "hisilicon,hi3798cv200"; diff --git a/Documentation/devicetree/bindings/arm/keystone/keystone.txt b/Documentation/devicetree/bindings/arm/keystone/keystone.txt index 48f6703a28c8..f310bad04483 100644 --- a/Documentation/devicetree/bindings/arm/keystone/keystone.txt +++ b/Documentation/devicetree/bindings/arm/keystone/keystone.txt @@ -37,3 +37,6 @@ Boards: - K2G EVM compatible = "ti,k2g-evm", "ti,k2g", "ti-keystone" + +- K2G Industrial Communication Engine EVM + compatible = "ti,k2g-ice", "ti,k2g", "ti-keystone" diff --git a/Documentation/devicetree/bindings/arm/mediatek.txt b/Documentation/devicetree/bindings/arm/mediatek.txt index c860b245d8c8..da7bd138e6f2 100644 --- a/Documentation/devicetree/bindings/arm/mediatek.txt +++ b/Documentation/devicetree/bindings/arm/mediatek.txt @@ -12,6 +12,8 @@ compatible: Must contain one of "mediatek,mt6592" "mediatek,mt6755" "mediatek,mt6795" + "mediatek,mt6797" + "mediatek,mt7622" "mediatek,mt7623" "mediatek,mt8127" "mediatek,mt8135" @@ -38,6 +40,12 @@ Supported boards: - Evaluation board for MT6795(Helio X10): Required root node properties: - compatible = "mediatek,mt6795-evb", "mediatek,mt6795"; +- Evaluation board for MT6797(Helio X20): + Required root node properties: + - compatible = "mediatek,mt6797-evb", "mediatek,mt6797"; +- Reference board variant 1 for MT7622: + Required root node properties: + - compatible = "mediatek,mt7622-rfb1", "mediatek,mt7622"; - Evaluation board for MT7623: Required root node properties: - compatible = "mediatek,mt7623-evb", "mediatek,mt7623"; diff --git a/Documentation/devicetree/bindings/arm/realtek.txt b/Documentation/devicetree/bindings/arm/realtek.txt new file mode 100644 index 000000000000..13d755787b4f --- /dev/null +++ b/Documentation/devicetree/bindings/arm/realtek.txt @@ -0,0 +1,20 @@ +Realtek platforms device tree bindings +-------------------------------------- + + +RTD1295 SoC +=========== + +Required root node properties: + + - compatible : must contain "realtek,rtd1295" + + +Root node property compatible must contain, depending on board: + + - Zidoo X9S: "zidoo,x9s" + + +Example: + + compatible = "zidoo,x9s", "realtek,rtd1295"; diff --git a/Documentation/devicetree/bindings/arm/rockchip.txt b/Documentation/devicetree/bindings/arm/rockchip.txt index c965d99e86c2..11c0ac4a2d56 100644 --- a/Documentation/devicetree/bindings/arm/rockchip.txt +++ b/Documentation/devicetree/bindings/arm/rockchip.txt @@ -42,6 +42,10 @@ Rockchip platforms device tree bindings Required root node properties: - compatible = "firefly,firefly-rk3288-reload", "rockchip,rk3288"; +- Firefly Firefly-RK3399 board: + Required root node properties: + - compatible = "firefly,firefly-rk3399", "rockchip,rk3399"; + - ChipSPARK PopMetal-RK3288 board: Required root node properties: - compatible = "chipspark,popmetal-rk3288", "rockchip,rk3288"; @@ -138,9 +142,9 @@ Rockchip platforms device tree bindings Required root node properties: - compatible = "rockchip,px5-evb", "rockchip,px5", "rockchip,rk3368"; -- Rockchip RK1108 Evaluation board +- Rockchip RV1108 Evaluation board Required root node properties: - - compatible = "rockchip,rk1108-evb", "rockchip,rk1108"; + - compatible = "rockchip,rv1108-evb", "rockchip,rv1108"; - Rockchip RK3368 evb: Required root node properties: diff --git a/Documentation/devicetree/bindings/arm/shmobile.txt b/Documentation/devicetree/bindings/arm/shmobile.txt index 170fe0562c63..1a671e329864 100644 --- a/Documentation/devicetree/bindings/arm/shmobile.txt +++ b/Documentation/devicetree/bindings/arm/shmobile.txt @@ -55,12 +55,19 @@ Boards: compatible = "renesas,bockw", "renesas,r8a7778" - Genmai (RTK772100BC00000BR) compatible = "renesas,genmai", "renesas,r7s72100" + - GR-Peach (X28A-M01-E/F) + compatible = "renesas,gr-peach", "renesas,r7s72100" - Gose (RTP0RC7793SEB00010S) compatible = "renesas,gose", "renesas,r8a7793" - - H3ULCB (R-Car Starter Kit Premier, RTP0RC7795SKB00010S) + - H3ULCB (R-Car Starter Kit Premier, RTP0RC7795SKBX0010SA00 (H3 ES1.1)) + H3ULCB (R-Car Starter Kit Premier, RTP0RC77951SKBX010SA00 (H3 ES2.0)) compatible = "renesas,h3ulcb", "renesas,r8a7795"; - Henninger compatible = "renesas,henninger", "renesas,r8a7791" + - iWave Systems RZ/G1M Qseven Development Platform (iW-RainboW-G20D-Qseven) + compatible = "iwave,g20d", "iwave,g20m", "renesas,r8a7743" + - iWave Systems RZ/G1M Qseven System On Module (iW-RainboW-G20M-Qseven) + compatible = "iwave,g20m", "renesas,r8a7743" - Koelsch (RTP0RC7791SEB00010S) compatible = "renesas,koelsch", "renesas,r8a7791" - Kyoto Microcomputer Co. KZM-A9-Dual @@ -69,7 +76,7 @@ Boards: compatible = "renesas,kzm9g", "renesas,sh73a0" - Lager (RTP0RC7790SEB00010S) compatible = "renesas,lager", "renesas,r8a7790" - - M3ULCB (R-Car Starter Kit Pro, RTP0RC7796SKB00010S) + - M3ULCB (R-Car Starter Kit Pro, RTP0RC7796SKBX0010SA09 (M3 ES1.0)) compatible = "renesas,m3ulcb", "renesas,r8a7796"; - Marzen (R0P7779A00010S) compatible = "renesas,marzen", "renesas,r8a7779" @@ -81,6 +88,8 @@ Boards: compatible = "renesas,salvator-x", "renesas,r8a7795"; - Salvator-X (RTP0RC7796SIPB0011S) compatible = "renesas,salvator-x", "renesas,r8a7796"; + - Salvator-XS (Salvator-X 2nd version, RTP0RC7795SIPB0012S) + compatible = "renesas,salvator-xs", "renesas,r8a7795"; - SILK (RTP0RC7794LCB00011S) compatible = "renesas,silk", "renesas,r8a7794" - SK-RZG1E (YR8A77450S000BE) diff --git a/Documentation/devicetree/bindings/arm/tegra.txt b/Documentation/devicetree/bindings/arm/tegra.txt index b5a4342c1d46..7f1411bbabf7 100644 --- a/Documentation/devicetree/bindings/arm/tegra.txt +++ b/Documentation/devicetree/bindings/arm/tegra.txt @@ -29,7 +29,6 @@ board-specific compatible values: nvidia,harmony nvidia,seaboard nvidia,ventana - nvidia,whistler toradex,apalis_t30 toradex,apalis_t30-eval toradex,apalis-tk1 diff --git a/Documentation/devicetree/bindings/ata/ahci-fsl-qoriq.txt b/Documentation/devicetree/bindings/ata/ahci-fsl-qoriq.txt index fc33ca01e9ba..7c3ca0e13de0 100644 --- a/Documentation/devicetree/bindings/ata/ahci-fsl-qoriq.txt +++ b/Documentation/devicetree/bindings/ata/ahci-fsl-qoriq.txt @@ -3,7 +3,7 @@ Binding for Freescale QorIQ AHCI SATA Controller Required properties: - reg: Physical base address and size of the controller's register area. - compatible: Compatibility string. Must be 'fsl,<chip>-ahci', where - chip could be ls1021a, ls1043a, ls1046a, ls2080a etc. + chip could be ls1021a, ls1043a, ls1046a, ls1088a, ls2080a etc. - clocks: Input clock specifier. Refer to common clock bindings. - interrupts: Interrupt specifier. Refer to interrupt binding. diff --git a/Documentation/devicetree/bindings/bus/brcm,gisb-arb.txt b/Documentation/devicetree/bindings/bus/brcm,gisb-arb.txt index 1eceefb20f01..8a6c3c2e58fe 100644 --- a/Documentation/devicetree/bindings/bus/brcm,gisb-arb.txt +++ b/Documentation/devicetree/bindings/bus/brcm,gisb-arb.txt @@ -3,7 +3,8 @@ Broadcom GISB bus Arbiter controller Required properties: - compatible: - "brcm,gisb-arb" or "brcm,bcm7445-gisb-arb" for 28nm chips + "brcm,bcm7278-gisb-arb" for V7 28nm chips + "brcm,gisb-arb" or "brcm,bcm7445-gisb-arb" for other 28nm chips "brcm,bcm7435-gisb-arb" for newer 40nm chips "brcm,bcm7400-gisb-arb" for older 40nm chips and all 65nm chips "brcm,bcm7038-gisb-arb" for 130nm chips diff --git a/Documentation/devicetree/bindings/clock/brcm,iproc-clocks.txt b/Documentation/devicetree/bindings/clock/brcm,iproc-clocks.txt index 6f66e9aa354c..f2c5f0e4a363 100644 --- a/Documentation/devicetree/bindings/clock/brcm,iproc-clocks.txt +++ b/Documentation/devicetree/bindings/clock/brcm,iproc-clocks.txt @@ -219,3 +219,79 @@ BCM63138 -------- PLL and leaf clock compatible strings for BCM63138 are: "brcm,bcm63138-armpll" + +Stingray +----------- +PLL and leaf clock compatible strings for Stingray are: + "brcm,sr-genpll0" + "brcm,sr-genpll1" + "brcm,sr-genpll2" + "brcm,sr-genpll3" + "brcm,sr-genpll4" + "brcm,sr-genpll5" + "brcm,sr-genpll6" + + "brcm,sr-lcpll0" + "brcm,sr-lcpll1" + "brcm,sr-lcpll-pcie" + + +The following table defines the set of PLL/clock index and ID for Stingray. +These clock IDs are defined in: + "include/dt-bindings/clock/bcm-sr.h" + + Clock Source Index ID + --- ----- ----- --------- + crystal N/A N/A N/A + crmu_ref25m crystal N/A N/A + + genpll0 crystal 0 BCM_SR_GENPLL0 + clk_125m genpll0 1 BCM_SR_GENPLL0_125M_CLK + clk_scr genpll0 2 BCM_SR_GENPLL0_SCR_CLK + clk_250 genpll0 3 BCM_SR_GENPLL0_250M_CLK + clk_pcie_axi genpll0 4 BCM_SR_GENPLL0_PCIE_AXI_CLK + clk_paxc_axi_x2 genpll0 5 BCM_SR_GENPLL0_PAXC_AXI_X2_CLK + clk_paxc_axi genpll0 6 BCM_SR_GENPLL0_PAXC_AXI_CLK + + genpll1 crystal 0 BCM_SR_GENPLL1 + clk_pcie_tl genpll1 1 BCM_SR_GENPLL1_PCIE_TL_CLK + clk_mhb_apb genpll1 2 BCM_SR_GENPLL1_MHB_APB_CLK + + genpll2 crystal 0 BCM_SR_GENPLL2 + clk_nic genpll2 1 BCM_SR_GENPLL2_NIC_CLK + clk_ts_500_ref genpll2 2 BCM_SR_GENPLL2_TS_500_REF_CLK + clk_125_nitro genpll2 3 BCM_SR_GENPLL2_125_NITRO_CLK + clk_chimp genpll2 4 BCM_SR_GENPLL2_CHIMP_CLK + clk_nic_flash genpll2 5 BCM_SR_GENPLL2_NIC_FLASH + + genpll3 crystal 0 BCM_SR_GENPLL3 + clk_hsls genpll3 1 BCM_SR_GENPLL3_HSLS_CLK + clk_sdio genpll3 2 BCM_SR_GENPLL3_SDIO_CLK + + genpll4 crystal 0 BCM_SR_GENPLL4 + ccn genpll4 1 BCM_SR_GENPLL4_CCN_CLK + clk_tpiu_pll genpll4 2 BCM_SR_GENPLL4_TPIU_PLL_CLK + noc_clk genpll4 3 BCM_SR_GENPLL4_NOC_CLK + clk_chclk_fs4 genpll4 4 BCM_SR_GENPLL4_CHCLK_FS4_CLK + clk_bridge_fscpu genpll4 5 BCM_SR_GENPLL4_BRIDGE_FSCPU_CLK + + + genpll5 crystal 0 BCM_SR_GENPLL5 + fs4_hf_clk genpll5 1 BCM_SR_GENPLL5_FS4_HF_CLK + crypto_ae_clk genpll5 2 BCM_SR_GENPLL5_CRYPTO_AE_CLK + raid_ae_clk genpll5 3 BCM_SR_GENPLL5_RAID_AE_CLK + + genpll6 crystal 0 BCM_SR_GENPLL6 + 48_usb genpll6 1 BCM_SR_GENPLL6_48_USB_CLK + + lcpll0 crystal 0 BCM_SR_LCPLL0 + clk_sata_refp lcpll0 1 BCM_SR_LCPLL0_SATA_REFP_CLK + clk_sata_refn lcpll0 2 BCM_SR_LCPLL0_SATA_REFN_CLK + clk_usb_ref lcpll0 3 BCM_SR_LCPLL0_USB_REF_CLK + sata_refpn lcpll0 3 BCM_SR_LCPLL0_SATA_REFPN_CLK + + lcpll1 crystal 0 BCM_SR_LCPLL1 + wan lcpll1 1 BCM_SR_LCPLL0_WAN_CLK + + lcpll_pcie crystal 0 BCM_SR_LCPLL_PCIE + pcie_phy_ref lcpll1 1 BCM_SR_LCPLL_PCIE_PHY_REF_CLK diff --git a/Documentation/devicetree/bindings/clock/sunxi-ccu.txt b/Documentation/devicetree/bindings/clock/sunxi-ccu.txt index e9c5a1d9834a..f465647a4dd2 100644 --- a/Documentation/devicetree/bindings/clock/sunxi-ccu.txt +++ b/Documentation/devicetree/bindings/clock/sunxi-ccu.txt @@ -22,7 +22,8 @@ Required properties : - #clock-cells : must contain 1 - #reset-cells : must contain 1 -For the PRCM CCUs on H3/A64, one more clock is needed: +For the PRCM CCUs on H3/A64, two more clocks are needed: +- "pll-periph": the SoC's peripheral PLL from the main CCU - "iosc": the SoC's internal frequency oscillator Example for generic CCU: @@ -39,8 +40,8 @@ Example for PRCM CCU: r_ccu: clock@01f01400 { compatible = "allwinner,sun50i-a64-r-ccu"; reg = <0x01f01400 0x100>; - clocks = <&osc24M>, <&osc32k>, <&iosc>; - clock-names = "hosc", "losc", "iosc"; + clocks = <&osc24M>, <&osc32k>, <&iosc>, <&ccu CLK_PLL_PERIPH0>; + clock-names = "hosc", "losc", "iosc", "pll-periph"; #clock-cells = <1>; #reset-cells = <1>; }; diff --git a/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt b/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt index ba0e15ad5bd9..0c38e4b8fc51 100644 --- a/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt +++ b/Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt @@ -63,64 +63,64 @@ cpu0_opp_table: opp-table { * because they can not be enabled simultaneously on a * single SoC. */ - opp50@300000000 { + opp50-300000000 { opp-hz = /bits/ 64 <300000000>; opp-microvolt = <950000 931000 969000>; opp-supported-hw = <0x06 0x0010>; opp-suspend; }; - opp100@275000000 { + opp100-275000000 { opp-hz = /bits/ 64 <275000000>; opp-microvolt = <1100000 1078000 1122000>; opp-supported-hw = <0x01 0x00FF>; opp-suspend; }; - opp100@300000000 { + opp100-300000000 { opp-hz = /bits/ 64 <300000000>; opp-microvolt = <1100000 1078000 1122000>; opp-supported-hw = <0x06 0x0020>; opp-suspend; }; - opp100@500000000 { + opp100-500000000 { opp-hz = /bits/ 64 <500000000>; opp-microvolt = <1100000 1078000 1122000>; opp-supported-hw = <0x01 0xFFFF>; }; - opp100@600000000 { + opp100-600000000 { opp-hz = /bits/ 64 <600000000>; opp-microvolt = <1100000 1078000 1122000>; opp-supported-hw = <0x06 0x0040>; }; - opp120@600000000 { + opp120-600000000 { opp-hz = /bits/ 64 <600000000>; opp-microvolt = <1200000 1176000 1224000>; opp-supported-hw = <0x01 0xFFFF>; }; - opp120@720000000 { + opp120-720000000 { opp-hz = /bits/ 64 <720000000>; opp-microvolt = <1200000 1176000 1224000>; opp-supported-hw = <0x06 0x0080>; }; - oppturbo@720000000 { + oppturbo-720000000 { opp-hz = /bits/ 64 <720000000>; opp-microvolt = <1260000 1234800 1285200>; opp-supported-hw = <0x01 0xFFFF>; }; - oppturbo@800000000 { + oppturbo-800000000 { opp-hz = /bits/ 64 <800000000>; opp-microvolt = <1260000 1234800 1285200>; opp-supported-hw = <0x06 0x0100>; }; - oppnitro@1000000000 { + oppnitro-1000000000 { opp-hz = /bits/ 64 <1000000000>; opp-microvolt = <1325000 1298500 1351500>; opp-supported-hw = <0x04 0x0200>; diff --git a/Documentation/devicetree/bindings/crypto/inside-secure-safexcel.txt b/Documentation/devicetree/bindings/crypto/inside-secure-safexcel.txt new file mode 100644 index 000000000000..f69773f4252b --- /dev/null +++ b/Documentation/devicetree/bindings/crypto/inside-secure-safexcel.txt @@ -0,0 +1,29 @@ +Inside Secure SafeXcel cryptographic engine + +Required properties: +- compatible: Should be "inside-secure,safexcel-eip197". +- reg: Base physical address of the engine and length of memory mapped region. +- interrupts: Interrupt numbers for the rings and engine. +- interrupt-names: Should be "ring0", "ring1", "ring2", "ring3", "eip", "mem". + +Optional properties: +- clocks: Reference to the crypto engine clock. +- dma-mask: The address mask limitation. Defaults to 64. + +Example: + + crypto: crypto@800000 { + compatible = "inside-secure,safexcel-eip197"; + reg = <0x800000 0x200000>; + interrupts = <GIC_SPI 34 IRQ_TYPE_LEVEL_HIGH>, + <GIC_SPI 54 IRQ_TYPE_LEVEL_HIGH>, + <GIC_SPI 55 IRQ_TYPE_LEVEL_HIGH>, + <GIC_SPI 56 IRQ_TYPE_LEVEL_HIGH>, + <GIC_SPI 57 IRQ_TYPE_LEVEL_HIGH>, + <GIC_SPI 58 IRQ_TYPE_LEVEL_HIGH>; + interrupt-names = "mem", "ring0", "ring1", "ring2", "ring3", + "eip"; + clocks = <&cpm_syscon0 1 26>; + dma-mask = <0xff 0xffffffff>; + status = "disabled"; + }; diff --git a/Documentation/devicetree/bindings/crypto/mediatek-crypto.txt b/Documentation/devicetree/bindings/crypto/mediatek-crypto.txt index c204725e5873..450da3661cad 100644 --- a/Documentation/devicetree/bindings/crypto/mediatek-crypto.txt +++ b/Documentation/devicetree/bindings/crypto/mediatek-crypto.txt @@ -6,8 +6,7 @@ Required properties: - interrupts: Should contain the five crypto engines interrupts in numeric order. These are global system and four descriptor rings. - clocks: the clock used by the core -- clock-names: the names of the clock listed in the clocks property. These are - "ethif", "cryp" +- clock-names: Must contain "cryp". - power-domains: Must contain a reference to the PM domain. @@ -20,8 +19,7 @@ Example: <GIC_SPI 84 IRQ_TYPE_LEVEL_LOW>, <GIC_SPI 91 IRQ_TYPE_LEVEL_LOW>, <GIC_SPI 97 IRQ_TYPE_LEVEL_LOW>; - clocks = <&topckgen CLK_TOP_ETHIF_SEL>, - <ðsys CLK_ETHSYS_CRYPTO>; - clock-names = "ethif","cryp"; + clocks = <ðsys CLK_ETHSYS_CRYPTO>; + clock-names = "cryp"; power-domains = <&scpsys MT2701_POWER_DOMAIN_ETH>; }; diff --git a/Documentation/devicetree/bindings/fsi/fsi-master-gpio.txt b/Documentation/devicetree/bindings/fsi/fsi-master-gpio.txt new file mode 100644 index 000000000000..a767259dedad --- /dev/null +++ b/Documentation/devicetree/bindings/fsi/fsi-master-gpio.txt @@ -0,0 +1,24 @@ +Device-tree bindings for gpio-based FSI master driver +----------------------------------------------------- + +Required properties: + - compatible = "fsi-master-gpio"; + - clock-gpios = <gpio-descriptor>; : GPIO for FSI clock + - data-gpios = <gpio-descriptor>; : GPIO for FSI data signal + +Optional properties: + - enable-gpios = <gpio-descriptor>; : GPIO for enable signal + - trans-gpios = <gpio-descriptor>; : GPIO for voltage translator enable + - mux-gpios = <gpio-descriptor>; : GPIO for pin multiplexing with other + functions (eg, external FSI masters) + +Examples: + + fsi-master { + compatible = "fsi-master-gpio", "fsi-master"; + clock-gpios = <&gpio 0>; + data-gpios = <&gpio 1>; + enable-gpios = <&gpio 2>; + trans-gpios = <&gpio 3>; + mux-gpios = <&gpio 4>; + } diff --git a/Documentation/devicetree/bindings/gpio/gpio-mvebu.txt b/Documentation/devicetree/bindings/gpio/gpio-mvebu.txt index 42c3bb2d53e8..01e331a5f3e7 100644 --- a/Documentation/devicetree/bindings/gpio/gpio-mvebu.txt +++ b/Documentation/devicetree/bindings/gpio/gpio-mvebu.txt @@ -41,9 +41,9 @@ Required properties: Optional properties: In order to use the GPIO lines in PWM mode, some additional optional -properties are required. Only Armada 370 and XP support these properties. +properties are required. -- compatible: Must contain "marvell,armada-370-xp-gpio" +- compatible: Must contain "marvell,armada-370-gpio" - reg: an additional register set is needed, for the GPIO Blink Counter on/off registers. @@ -71,7 +71,7 @@ Example: }; gpio1: gpio@18140 { - compatible = "marvell,armada-370-xp-gpio"; + compatible = "marvell,armada-370-gpio"; reg = <0x18140 0x40>, <0x181c8 0x08>; reg-names = "gpio", "pwm"; ngpios = <17>; diff --git a/Documentation/devicetree/bindings/gpio/gpio_atmel.txt b/Documentation/devicetree/bindings/gpio/gpio_atmel.txt index 85f8c0d084fa..29416f9c3220 100644 --- a/Documentation/devicetree/bindings/gpio/gpio_atmel.txt +++ b/Documentation/devicetree/bindings/gpio/gpio_atmel.txt @@ -5,9 +5,13 @@ Required properties: - reg: Should contain GPIO controller registers location and length - interrupts: Should be the port interrupt shared by all the pins. - #gpio-cells: Should be two. The first cell is the pin number and - the second cell is used to specify optional parameters (currently - unused). + the second cell is used to specify optional parameters to declare if the GPIO + is active high or low. See gpio.txt. - gpio-controller: Marks the device node as a GPIO controller. +- interrupt-controller: Marks the device node as an interrupt controller. +- #interrupt-cells: Should be two. The first cell is the pin number and the + second cell is used to specify irq type flags, see the two cell description + in interrupt-controller/interrupts.txt for details. optional properties: - #gpio-lines: Number of gpio if absent 32. @@ -21,5 +25,7 @@ Example: #gpio-cells = <2>; gpio-controller; #gpio-lines = <19>; + interrupt-controller; + #interrupt-cells = <2>; }; diff --git a/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt new file mode 100644 index 000000000000..d3b6e1a4713a --- /dev/null +++ b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt @@ -0,0 +1,86 @@ +ARM Mali Midgard GPU +==================== + +Required properties: + +- compatible : + * Must contain one of the following: + + "arm,mali-t604" + + "arm,mali-t624" + + "arm,mali-t628" + + "arm,mali-t720" + + "arm,mali-t760" + + "arm,mali-t820" + + "arm,mali-t830" + + "arm,mali-t860" + + "arm,mali-t880" + * which must be preceded by one of the following vendor specifics: + + "amlogic,meson-gxm-mali" + + "rockchip,rk3288-mali" + +- reg : Physical base address of the device and length of the register area. + +- interrupts : Contains the three IRQ lines required by Mali Midgard devices. + +- interrupt-names : Contains the names of IRQ resources in the order they were + provided in the interrupts property. Must contain: "job", "mmu", "gpu". + + +Optional properties: + +- clocks : Phandle to clock for the Mali Midgard device. + +- mali-supply : Phandle to regulator for the Mali device. Refer to + Documentation/devicetree/bindings/regulator/regulator.txt for details. + +- operating-points-v2 : Refer to Documentation/devicetree/bindings/power/opp.txt + for details. + + +Example for a Mali-T760: + +gpu@ffa30000 { + compatible = "rockchip,rk3288-mali", "arm,mali-t760", "arm,mali-midgard"; + reg = <0xffa30000 0x10000>; + interrupts = <GIC_SPI 6 IRQ_TYPE_LEVEL_HIGH>, + <GIC_SPI 7 IRQ_TYPE_LEVEL_HIGH>, + <GIC_SPI 8 IRQ_TYPE_LEVEL_HIGH>; + interrupt-names = "job", "mmu", "gpu"; + clocks = <&cru ACLK_GPU>; + mali-supply = <&vdd_gpu>; + operating-points-v2 = <&gpu_opp_table>; + power-domains = <&power RK3288_PD_GPU>; +}; + +gpu_opp_table: opp_table0 { + compatible = "operating-points-v2"; + + opp@533000000 { + opp-hz = /bits/ 64 <533000000>; + opp-microvolt = <1250000>; + }; + opp@450000000 { + opp-hz = /bits/ 64 <450000000>; + opp-microvolt = <1150000>; + }; + opp@400000000 { + opp-hz = /bits/ 64 <400000000>; + opp-microvolt = <1125000>; + }; + opp@350000000 { + opp-hz = /bits/ 64 <350000000>; + opp-microvolt = <1075000>; + }; + opp@266000000 { + opp-hz = /bits/ 64 <266000000>; + opp-microvolt = <1025000>; + }; + opp@160000000 { + opp-hz = /bits/ 64 <160000000>; + opp-microvolt = <925000>; + }; + opp@100000000 { + opp-hz = /bits/ 64 <100000000>; + opp-microvolt = <912500>; + }; +}; diff --git a/Documentation/devicetree/bindings/i2c/i2c-mt6577.txt b/Documentation/devicetree/bindings/i2c/i2c-mtk.txt index 0ce6fa3242f0..bd5a7befd951 100644 --- a/Documentation/devicetree/bindings/i2c/i2c-mt6577.txt +++ b/Documentation/devicetree/bindings/i2c/i2c-mtk.txt @@ -4,11 +4,11 @@ The Mediatek's I2C controller is used to interface with I2C devices. Required properties: - compatible: value should be either of the following. - (a) "mediatek,mt6577-i2c", for i2c compatible with mt6577 i2c. - (b) "mediatek,mt6589-i2c", for i2c compatible with mt6589 i2c. - (c) "mediatek,mt8127-i2c", for i2c compatible with mt8127 i2c. - (d) "mediatek,mt8135-i2c", for i2c compatible with mt8135 i2c. - (e) "mediatek,mt8173-i2c", for i2c compatible with mt8173 i2c. + "mediatek,mt2701-i2c", "mediatek,mt6577-i2c": for Mediatek mt2701 + "mediatek,mt6577-i2c": for i2c compatible with mt6577. + "mediatek,mt6589-i2c": for i2c compatible with mt6589. + "mediatek,mt7623-i2c", "mediatek,mt6577-i2c": for i2c compatible with mt7623. + "mediatek,mt8173-i2c": for i2c compatible with mt8173. - reg: physical base address of the controller and dma base, length of memory mapped region. - interrupts: interrupt number to the cpu. diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-gpmux.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-gpmux.txt new file mode 100644 index 000000000000..2907dab56298 --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-gpmux.txt @@ -0,0 +1,99 @@ +General Purpose I2C Bus Mux + +This binding describes an I2C bus multiplexer that uses a mux controller +from the mux subsystem to route the I2C signals. + + .-----. .-----. + | dev | | dev | + .------------. '-----' '-----' + | SoC | | | + | | .--------+--------' + | .------. | .------+ child bus A, on MUX value set to 0 + | | I2C |-|--| Mux | + | '------' | '--+---+ child bus B, on MUX value set to 1 + | .------. | | '----------+--------+--------. + | | MUX- | | | | | | + | | Ctrl |-|-----+ .-----. .-----. .-----. + | '------' | | dev | | dev | | dev | + '------------' '-----' '-----' '-----' + +Required properties: +- compatible: i2c-mux +- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side + port is connected to. +- mux-controls: The phandle of the mux controller to use for operating the + mux. +* Standard I2C mux properties. See i2c-mux.txt in this directory. +* I2C child bus nodes. See i2c-mux.txt in this directory. The sub-bus number + is also the mux-controller state described in ../mux/mux-controller.txt + +Optional properties: +- mux-locked: If present, explicitly allow unrelated I2C transactions on the + parent I2C adapter at these times: + + during setup of the multiplexer + + between setup of the multiplexer and the child bus I2C transaction + + between the child bus I2C transaction and releasing of the multiplexer + + during releasing of the multiplexer + However, I2C transactions to devices behind all I2C multiplexers connected + to the same parent adapter that this multiplexer is connected to are blocked + for the full duration of the complete multiplexed I2C transaction (i.e. + including the times covered by the above list). + If mux-locked is not present, the multiplexer is assumed to be parent-locked. + This means that no unrelated I2C transactions are allowed on the parent I2C + adapter for the complete multiplexed I2C transaction. + The properties of mux-locked and parent-locked multiplexers are discussed + in more detail in Documentation/i2c/i2c-topology. + +For each i2c child node, an I2C child bus will be created. They will +be numbered based on their order in the device tree. + +Whenever an access is made to a device on a child bus, the value set +in the relevant node's reg property will be set as the state in the +mux controller. + +Example: + mux: mux-controller { + compatible = "gpio-mux"; + #mux-control-cells = <0>; + + mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>, + <&pioA 1 GPIO_ACTIVE_HIGH>; + }; + + i2c-mux { + compatible = "i2c-mux"; + mux-locked; + i2c-parent = <&i2c1>; + + mux-controls = <&mux>; + + #address-cells = <1>; + #size-cells = <0>; + + i2c@1 { + reg = <1>; + #address-cells = <1>; + #size-cells = <0>; + + ssd1307: oled@3c { + compatible = "solomon,ssd1307fb-i2c"; + reg = <0x3c>; + pwms = <&pwm 4 3000>; + reset-gpios = <&gpio2 7 1>; + reset-active-low; + }; + }; + + i2c@3 { + reg = <3>; + #address-cells = <1>; + #size-cells = <0>; + + pca9555: pca9555@20 { + compatible = "nxp,pca9555"; + gpio-controller; + #gpio-cells = <2>; + reg = <0x20>; + }; + }; + }; diff --git a/Documentation/devicetree/bindings/iio/adc/amlogic,meson-saradc.txt b/Documentation/devicetree/bindings/iio/adc/amlogic,meson-saradc.txt index 047189192aec..f413e82c8b83 100644 --- a/Documentation/devicetree/bindings/iio/adc/amlogic,meson-saradc.txt +++ b/Documentation/devicetree/bindings/iio/adc/amlogic,meson-saradc.txt @@ -2,6 +2,8 @@ Required properties: - compatible: depending on the SoC this should be one of: + - "amlogic,meson8-saradc" for Meson8 + - "amlogic,meson8b-saradc" for Meson8b - "amlogic,meson-gxbb-saradc" for GXBB - "amlogic,meson-gxl-saradc" for GXL - "amlogic,meson-gxm-saradc" for GXM diff --git a/Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt b/Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt index f5b0adae6010..df5b9f2ad8d8 100644 --- a/Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt +++ b/Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt @@ -1,4 +1,4 @@ -* Renesas RCar GyroADC device driver +* Renesas R-Car GyroADC device driver The GyroADC block is a reduced SPI block with up to 8 chipselect lines, which supports the SPI protocol of a selected few SPI ADCs. The SPI ADCs @@ -16,8 +16,7 @@ Required properties: - clocks: References to all the clocks specified in the clock-names property as specified in Documentation/devicetree/bindings/clock/clock-bindings.txt. -- clock-names: Shall contain "fck" and "if". The "fck" is the GyroADC block - clock, the "if" is the interface clock. +- clock-names: Shall contain "fck". The "fck" is the GyroADC block clock. - power-domains: Must contain a reference to the PM domain, if available. - #address-cells: Should be <1> (setting for the subnodes) for all ADCs except for "fujitsu,mb88101a". Should be <0> (setting for @@ -75,8 +74,8 @@ Example: adc@e6e54000 { compatible = "renesas,r8a7791-gyroadc", "renesas,rcar-gyroadc"; reg = <0 0xe6e54000 0 64>; - clocks = <&mstp9_clks R8A7791_CLK_GYROADC>, <&clk_65m>; - clock-names = "fck", "if"; + clocks = <&mstp9_clks R8A7791_CLK_GYROADC>; + clock-names = "fck"; power-domains = <&sysc R8A7791_PD_ALWAYS_ON>; pinctrl-0 = <&adc_pins>; diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt index e35f9f1b3200..8310073f14e1 100644 --- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt +++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt @@ -21,11 +21,19 @@ own configurable sequence and trigger: Contents of a stm32 adc root node: ----------------------------------- Required properties: -- compatible: Should be "st,stm32f4-adc-core". +- compatible: Should be one of: + "st,stm32f4-adc-core" + "st,stm32h7-adc-core" - reg: Offset and length of the ADC block register set. - interrupts: Must contain the interrupt for ADC block. -- clocks: Clock for the analog circuitry (common to all ADCs). -- clock-names: Must be "adc". +- clocks: Core can use up to two clocks, depending on part used: + - "adc" clock: for the analog circuitry, common to all ADCs. + It's required on stm32f4. + It's optional on stm32h7. + - "bus" clock: for registers access, common to all ADCs. + It's not present on stm32f4. + It's required on stm32h7. +- clock-names: Must be "adc" and/or "bus" depending on part used. - interrupt-controller: Identifies the controller node as interrupt-parent - vref-supply: Phandle to the vref input analog reference voltage. - #interrupt-cells = <1>; @@ -42,14 +50,18 @@ An ADC block node should contain at least one subnode, representing an ADC instance available on the machine. Required properties: -- compatible: Should be "st,stm32f4-adc". +- compatible: Should be one of: + "st,stm32f4-adc" + "st,stm32h7-adc" - reg: Offset of ADC instance in ADC block (e.g. may be 0x0, 0x100, 0x200). -- clocks: Input clock private to this ADC instance. +- clocks: Input clock private to this ADC instance. It's required only on + stm32f4, that has per instance clock input for registers access. - interrupt-parent: Phandle to the parent interrupt controller. - interrupts: IRQ Line for the ADC (e.g. may be 0 for adc@0, 1 for adc@100 or 2 for adc@200). - st,adc-channels: List of single-ended channels muxed for this ADC. - It can have up to 16 channels, numbered from 0 to 15 (resp. for in0..in15). + It can have up to 16 channels on stm32f4 or 20 channels on stm32h7, numbered + from 0 to 15 or 19 (resp. for in0..in15 or in0..in19). - #io-channel-cells = <1>: See the IIO bindings section "IIO consumers" in Documentation/devicetree/bindings/iio/iio-bindings.txt @@ -58,7 +70,9 @@ Optional properties: See ../../dma/dma.txt for details. - dma-names: Must be "rx" when dmas property is being used. - assigned-resolution-bits: Resolution (bits) to use for conversions. Must - match device available resolutions (e.g. can be 6, 8, 10 or 12 on stm32f4). + match device available resolutions: + * can be 6, 8, 10 or 12 on stm32f4 + * can be 8, 10, 12, 14 or 16 on stm32h7 Default is maximum resolution if unset. Example: diff --git a/Documentation/devicetree/bindings/iio/adc/ti-adc084s021.txt b/Documentation/devicetree/bindings/iio/adc/ti-adc084s021.txt new file mode 100644 index 000000000000..4259e50620bc --- /dev/null +++ b/Documentation/devicetree/bindings/iio/adc/ti-adc084s021.txt @@ -0,0 +1,19 @@ +* Texas Instruments' ADC084S021 + +Required properties: + - compatible : Must be "ti,adc084s021" + - reg : SPI chip select number for the device + - vref-supply : The regulator supply for ADC reference voltage + - spi-cpol : Per spi-bus bindings + - spi-cpha : Per spi-bus bindings + - spi-max-frequency : Per spi-bus bindings + +Example: +adc@0 { + compatible = "ti,adc084s021"; + reg = <0>; + vref-supply = <&adc_vref>; + spi-cpol; + spi-cpha; + spi-max-frequency = <16000000>; +}; diff --git a/Documentation/devicetree/bindings/iio/adc/ti-adc108s102.txt b/Documentation/devicetree/bindings/iio/adc/ti-adc108s102.txt new file mode 100644 index 000000000000..bbbbb4a9f58f --- /dev/null +++ b/Documentation/devicetree/bindings/iio/adc/ti-adc108s102.txt @@ -0,0 +1,18 @@ +* Texas Instruments' ADC108S102 and ADC128S102 ADC chip + +Required properties: + - compatible: Should be "ti,adc108s102" + - reg: spi chip select number for the device + - vref-supply: The regulator supply for ADC reference voltage + +Recommended properties: + - spi-max-frequency: Definition as per + Documentation/devicetree/bindings/spi/spi-bus.txt + +Example: +adc@0 { + compatible = "ti,adc108s102"; + reg = <0>; + vref-supply = <&vdd_supply>; + spi-max-frequency = <1000000>; +}; diff --git a/Documentation/devicetree/bindings/iio/imu/st_lsm6dsx.txt b/Documentation/devicetree/bindings/iio/imu/st_lsm6dsx.txt index 8305fb05ffda..6f28ff55f3ec 100644 --- a/Documentation/devicetree/bindings/iio/imu/st_lsm6dsx.txt +++ b/Documentation/devicetree/bindings/iio/imu/st_lsm6dsx.txt @@ -13,7 +13,8 @@ Optional properties: "data ready" (valid values: 1 or 2). - interrupt-parent: should be the phandle for the interrupt controller - interrupts: interrupt mapping for IRQ. It should be configured with - flags IRQ_TYPE_LEVEL_HIGH or IRQ_TYPE_EDGE_RISING. + flags IRQ_TYPE_LEVEL_HIGH, IRQ_TYPE_EDGE_RISING, IRQ_TYPE_LEVEL_LOW or + IRQ_TYPE_EDGE_FALLING. Refer to interrupt-controller/interrupts.txt for generic interrupt client node bindings. diff --git a/Documentation/devicetree/bindings/iio/multiplexer/io-channel-mux.txt b/Documentation/devicetree/bindings/iio/multiplexer/io-channel-mux.txt new file mode 100644 index 000000000000..c82794002595 --- /dev/null +++ b/Documentation/devicetree/bindings/iio/multiplexer/io-channel-mux.txt @@ -0,0 +1,39 @@ +I/O channel multiplexer bindings + +If a multiplexer is used to select which hardware signal is fed to +e.g. an ADC channel, these bindings describe that situation. + +Required properties: +- compatible : "io-channel-mux" +- io-channels : Channel node of the parent channel that has multiplexed + input. +- io-channel-names : Should be "parent". +- #address-cells = <1>; +- #size-cells = <0>; +- mux-controls : Mux controller node to use for operating the mux +- channels : List of strings, labeling the mux controller states. + +For each non-empty string in the channels property, an io-channel will +be created. The number of this io-channel is the same as the index into +the list of strings in the channels property, and also matches the mux +controller state. The mux controller state is described in +../mux/mux-controller.txt + +Example: + mux: mux-controller { + compatible = "mux-gpio"; + #mux-control-cells = <0>; + + mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>, + <&pioA 1 GPIO_ACTIVE_HIGH>; + }; + + adc-mux { + compatible = "io-channel-mux"; + io-channels = <&adc 0>; + io-channel-names = "parent"; + + mux-controls = <&mux>; + + channels = "sync", "in", "system-regulator"; + }; diff --git a/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt index 6db22103e2dd..025cf8c9324a 100644 --- a/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt +++ b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt @@ -36,7 +36,7 @@ Optional properties: control gpios - threshold: allows setting the "click"-threshold in the range - from 20 to 80. + from 0 to 80. - gain: allows setting the sensitivity in the range from 0 to 31. Note that lower values indicate higher diff --git a/Documentation/devicetree/bindings/interrupt-controller/allwinner,sunxi-nmi.txt b/Documentation/devicetree/bindings/interrupt-controller/allwinner,sunxi-nmi.txt index 81cd3692405e..4ae553eb333d 100644 --- a/Documentation/devicetree/bindings/interrupt-controller/allwinner,sunxi-nmi.txt +++ b/Documentation/devicetree/bindings/interrupt-controller/allwinner,sunxi-nmi.txt @@ -3,8 +3,11 @@ Allwinner Sunxi NMI Controller Required properties: -- compatible : should be "allwinner,sun7i-a20-sc-nmi" or - "allwinner,sun6i-a31-sc-nmi" or "allwinner,sun9i-a80-nmi" +- compatible : should be one of the following: + - "allwinner,sun7i-a20-sc-nmi" + - "allwinner,sun6i-a31-sc-nmi" (deprecated) + - "allwinner,sun6i-a31-r-intc" + - "allwinner,sun9i-a80-nmi" - reg : Specifies base physical address and size of the registers. - interrupt-controller : Identifies the node as an interrupt controller - #interrupt-cells : Specifies the number of cells needed to encode an diff --git a/Documentation/devicetree/bindings/interrupt-controller/aspeed,ast2400-i2c-ic.txt b/Documentation/devicetree/bindings/interrupt-controller/aspeed,ast2400-i2c-ic.txt new file mode 100644 index 000000000000..033cc82e5684 --- /dev/null +++ b/Documentation/devicetree/bindings/interrupt-controller/aspeed,ast2400-i2c-ic.txt @@ -0,0 +1,25 @@ +Device tree configuration for the I2C Interrupt Controller on the AST24XX and +AST25XX SoCs. + +Required Properties: +- #address-cells : should be 1 +- #size-cells : should be 1 +- #interrupt-cells : should be 1 +- compatible : should be "aspeed,ast2400-i2c-ic" + or "aspeed,ast2500-i2c-ic" +- reg : address start and range of controller +- interrupts : interrupt number +- interrupt-controller : denotes that the controller receives and fires + new interrupts for child busses + +Example: + +i2c_ic: interrupt-controller@0 { + #address-cells = <1>; + #size-cells = <1>; + #interrupt-cells = <1>; + compatible = "aspeed,ast2400-i2c-ic"; + reg = <0x0 0x40>; + interrupts = <12>; + interrupt-controller; +}; diff --git a/Documentation/devicetree/bindings/interrupt-controller/aspeed,ast2400-vic.txt b/Documentation/devicetree/bindings/interrupt-controller/aspeed,ast2400-vic.txt index 6c6e85324b9d..e3fea0758d25 100644 --- a/Documentation/devicetree/bindings/interrupt-controller/aspeed,ast2400-vic.txt +++ b/Documentation/devicetree/bindings/interrupt-controller/aspeed,ast2400-vic.txt @@ -1,12 +1,13 @@ Aspeed Vectored Interrupt Controller -These bindings are for the Aspeed AST2400 interrupt controller register layout. -The SoC has an legacy register layout, but this driver does not support that -mode of operation. +These bindings are for the Aspeed interrupt controller. The AST2400 and +AST2500 SoC families include a legacy register layout before a re-designed +layout, but the bindings do not prescribe the use of one or the other. Required properties: -- compatible : should be "aspeed,ast2400-vic". +- compatible : "aspeed,ast2400-vic" + "aspeed,ast2500-vic" - interrupt-controller : Identifies the node as an interrupt controller - #interrupt-cells : Specifies the number of cells needed to encode an diff --git a/Documentation/devicetree/bindings/interrupt-controller/marvell,gicp.txt b/Documentation/devicetree/bindings/interrupt-controller/marvell,gicp.txt new file mode 100644 index 000000000000..64a00ceb7da4 --- /dev/null +++ b/Documentation/devicetree/bindings/interrupt-controller/marvell,gicp.txt @@ -0,0 +1,27 @@ +Marvell GICP Controller +----------------------- + +GICP is a Marvell extension of the GIC that allows to trigger GIC SPI +interrupts by doing a memory transaction. It is used by the ICU +located in the Marvell CP110 to turn wired interrupts inside the CP +into GIC SPI interrupts. + +Required properties: + +- compatible: Must be "marvell,ap806-gicp" + +- reg: Must be the address and size of the GICP SPI registers + +- marvell,spi-ranges: tuples of GIC SPI interrupts ranges available + for this GICP + +- msi-controller: indicates that this is an MSI controller + +Example: + +gicp_spi: gicp-spi@3f0040 { + compatible = "marvell,ap806-gicp"; + reg = <0x3f0040 0x10>; + marvell,spi-ranges = <64 64>, <288 64>; + msi-controller; +}; diff --git a/Documentation/devicetree/bindings/interrupt-controller/marvell,icu.txt b/Documentation/devicetree/bindings/interrupt-controller/marvell,icu.txt new file mode 100644 index 000000000000..aa8bf2ec8905 --- /dev/null +++ b/Documentation/devicetree/bindings/interrupt-controller/marvell,icu.txt @@ -0,0 +1,51 @@ +Marvell ICU Interrupt Controller +-------------------------------- + +The Marvell ICU (Interrupt Consolidation Unit) controller is +responsible for collecting all wired-interrupt sources in the CP and +communicating them to the GIC in the AP, the unit translates interrupt +requests on input wires to MSG memory mapped transactions to the GIC. + +Required properties: + +- compatible: Should be "marvell,cp110-icu" + +- reg: Should contain ICU registers location and length. + +- #interrupt-cells: Specifies the number of cells needed to encode an + interrupt source. The value shall be 3. + + The 1st cell is the group type of the ICU interrupt. Possible group + types are: + + ICU_GRP_NSR (0x0) : Shared peripheral interrupt, non-secure + ICU_GRP_SR (0x1) : Shared peripheral interrupt, secure + ICU_GRP_SEI (0x4) : System error interrupt + ICU_GRP_REI (0x5) : RAM error interrupt + + The 2nd cell is the index of the interrupt in the ICU unit. + + The 3rd cell is the type of the interrupt. See arm,gic.txt for + details. + +- interrupt-controller: Identifies the node as an interrupt + controller. + +- msi-parent: Should point to the GICP controller, the GIC extension + that allows to trigger interrupts using MSG memory mapped + transactions. + +Example: + +icu: interrupt-controller@1e0000 { + compatible = "marvell,cp110-icu"; + reg = <0x1e0000 0x10>; + #interrupt-cells = <3>; + interrupt-controller; + msi-parent = <&gicp>; +}; + +usb3h0: usb3@500000 { + interrupt-parent = <&icu>; + interrupts = <ICU_GRP_NSR 106 IRQ_TYPE_LEVEL_HIGH>; +}; diff --git a/Documentation/devicetree/bindings/interrupt-controller/mediatek,sysirq.txt b/Documentation/devicetree/bindings/interrupt-controller/mediatek,sysirq.txt index a89c03bb1a81..11cc87aeb276 100644 --- a/Documentation/devicetree/bindings/interrupt-controller/mediatek,sysirq.txt +++ b/Documentation/devicetree/bindings/interrupt-controller/mediatek,sysirq.txt @@ -1,21 +1,23 @@ -+Mediatek 65xx/67xx/81xx sysirq ++Mediatek MT65xx/MT67xx/MT81xx sysirq Mediatek SOCs sysirq support controllable irq inverter for each GIC SPI interrupt. Required properties: -- compatible: should be one of: - "mediatek,mt8173-sysirq" - "mediatek,mt8135-sysirq" - "mediatek,mt8127-sysirq" - "mediatek,mt6795-sysirq" - "mediatek,mt6755-sysirq" - "mediatek,mt6592-sysirq" - "mediatek,mt6589-sysirq" - "mediatek,mt6582-sysirq" - "mediatek,mt6580-sysirq" - "mediatek,mt6577-sysirq" - "mediatek,mt2701-sysirq" +- compatible: should be + "mediatek,mt8173-sysirq", "mediatek,mt6577-sysirq": for MT8173 + "mediatek,mt8135-sysirq", "mediatek,mt6577-sysirq": for MT8135 + "mediatek,mt8127-sysirq", "mediatek,mt6577-sysirq": for MT8127 + "mediatek,mt7622-sysirq", "mediatek,mt6577-sysirq": for MT7622 + "mediatek,mt6795-sysirq", "mediatek,mt6577-sysirq": for MT6795 + "mediatek,mt6797-sysirq", "mediatek,mt6577-sysirq": for MT6797 + "mediatek,mt6755-sysirq", "mediatek,mt6577-sysirq": for MT6755 + "mediatek,mt6592-sysirq", "mediatek,mt6577-sysirq": for MT6592 + "mediatek,mt6589-sysirq", "mediatek,mt6577-sysirq": for MT6589 + "mediatek,mt6582-sysirq", "mediatek,mt6577-sysirq": for MT6582 + "mediatek,mt6580-sysirq", "mediatek,mt6577-sysirq": for MT6580 + "mediatek,mt6577-sysirq": for MT6577 + "mediatek,mt2701-sysirq", "mediatek,mt6577-sysirq": for MT2701 - interrupt-controller : Identifies the node as an interrupt controller - #interrupt-cells : Use the same format as specified by GIC in arm,gic.txt. - interrupt-parent: phandle of irq parent for sysirq. The parent must diff --git a/Documentation/devicetree/bindings/leds/common.txt b/Documentation/devicetree/bindings/leds/common.txt index 24b656014089..1d4afe9644b6 100644 --- a/Documentation/devicetree/bindings/leds/common.txt +++ b/Documentation/devicetree/bindings/leds/common.txt @@ -1,4 +1,4 @@ -Common leds properties. +* Common leds properties. LED and flash LED devices provide the same basic functionality as current regulators, but extended with LED and flash LED specific features like @@ -49,6 +49,22 @@ Optional properties for child nodes: - panic-indicator : This property specifies that the LED should be used, if at all possible, as a panic indicator. +- trigger-sources : List of devices which should be used as a source triggering + this LED activity. Some LEDs can be related to a specific + device and should somehow indicate its state. E.g. USB 2.0 + LED may react to device(s) in a USB 2.0 port(s). + Another common example is switch or router with multiple + Ethernet ports each of them having its own LED assigned + (assuming they are not hardwired). In such cases this + property should contain phandle(s) of related source + device(s). + In many cases LED can be related to more than one device + (e.g. one USB LED vs. multiple USB ports). Each source + should be represented by a node in the device tree and be + referenced by a phandle and a set of phandle arguments. A + length of arguments should be specified by the + #trigger-source-cells property in the source node. + Required properties for flash LED child nodes: - flash-max-microamp : Maximum flash LED supply current in microamperes. - flash-max-timeout-us : Maximum timeout in microseconds after which the flash @@ -59,7 +75,17 @@ property can be omitted. For controllers that have no configurable timeout the flash-max-timeout-us property can be omitted. -Examples: +* Trigger source providers + +Each trigger source should be represented by a device tree node. It may be e.g. +a USB port or an Ethernet device. + +Required properties for trigger source: +- #trigger-source-cells : Number of cells in a source trigger. Typically 0 for + nodes of simple trigger sources (e.g. a specific USB + port). + +* Examples gpio-leds { compatible = "gpio-leds"; @@ -69,6 +95,11 @@ gpio-leds { linux,default-trigger = "heartbeat"; gpios = <&gpio0 0 GPIO_ACTIVE_HIGH>; }; + + usb { + gpios = <&gpio0 1 GPIO_ACTIVE_HIGH>; + trigger-sources = <&ohci_port1>, <&ehci_port1>; + }; }; max77693-led { diff --git a/Documentation/devicetree/bindings/mfd/hi6421.txt b/Documentation/devicetree/bindings/mfd/hi6421.txt index 0d5a4466a494..22da96d344a7 100644 --- a/Documentation/devicetree/bindings/mfd/hi6421.txt +++ b/Documentation/devicetree/bindings/mfd/hi6421.txt @@ -1,7 +1,9 @@ * HI6421 Multi-Functional Device (MFD), by HiSilicon Ltd. Required parent device properties: -- compatible : contains "hisilicon,hi6421-pmic"; +- compatible : One of the following chip-specific strings: + "hisilicon,hi6421-pmic"; + "hisilicon,hi6421v530-pmic"; - reg : register range space of hi6421; Supported Hi6421 sub-devices include: diff --git a/Documentation/devicetree/bindings/mfd/hisilicon,hi655x.txt b/Documentation/devicetree/bindings/mfd/hisilicon,hi655x.txt index 05485699d70e..9630ac0e4b56 100644 --- a/Documentation/devicetree/bindings/mfd/hisilicon,hi655x.txt +++ b/Documentation/devicetree/bindings/mfd/hisilicon,hi655x.txt @@ -16,6 +16,11 @@ Required properties: - reg: Base address of PMIC on Hi6220 SoC. - interrupt-controller: Hi655x has internal IRQs (has own IRQ domain). - pmic-gpios: The GPIO used by PMIC IRQ. +- #clock-cells: From common clock binding; shall be set to 0 + +Optional properties: +- clock-output-names: From common clock binding to override the + default output clock name Example: pmic: pmic@f8000000 { @@ -24,4 +29,5 @@ Example: interrupt-controller; #interrupt-cells = <2>; pmic-gpios = <&gpio1 2 GPIO_ACTIVE_HIGH>; + #clock-cells = <0>; } diff --git a/Documentation/devicetree/bindings/mfd/stm32-timers.txt b/Documentation/devicetree/bindings/mfd/stm32-timers.txt index bbd083f5600a..1db6e0057a63 100644 --- a/Documentation/devicetree/bindings/mfd/stm32-timers.txt +++ b/Documentation/devicetree/bindings/mfd/stm32-timers.txt @@ -31,7 +31,7 @@ Example: compatible = "st,stm32-timers"; reg = <0x40010000 0x400>; clocks = <&rcc 0 160>; - clock-names = "clk_int"; + clock-names = "int"; pwm { compatible = "st,stm32-pwm"; diff --git a/Documentation/devicetree/bindings/mfd/tps65910.txt b/Documentation/devicetree/bindings/mfd/tps65910.txt index 38833e63a59f..8af1202b381d 100644 --- a/Documentation/devicetree/bindings/mfd/tps65910.txt +++ b/Documentation/devicetree/bindings/mfd/tps65910.txt @@ -61,6 +61,10 @@ Optional properties: There should be 9 entries here, one for each gpio. - ti,system-power-controller: Telling whether or not this pmic is controlling the system power. +- ti,sleep-enable: Enable SLEEP state. +- ti,sleep-keep-therm: Keep thermal monitoring on in sleep state. +- ti,sleep-keep-ck32k: Keep the 32KHz clock output on in sleep state. +- ti,sleep-keep-hsclk: Keep high speed internal clock on in sleep state. Regulator Optional properties: - ti,regulator-ext-sleep-control: enable external sleep diff --git a/Documentation/devicetree/bindings/misc/allwinner,syscon.txt b/Documentation/devicetree/bindings/misc/allwinner,syscon.txt new file mode 100644 index 000000000000..31494a24fe69 --- /dev/null +++ b/Documentation/devicetree/bindings/misc/allwinner,syscon.txt @@ -0,0 +1,20 @@ +* Allwinner sun8i system controller + +This file describes the bindings for the system controller present in +Allwinner SoC H3, A83T and A64. +The principal function of this syscon is to control EMAC PHY choice and +config. + +Required properties for the system controller: +- reg: address and length of the register for the device. +- compatible: should be "syscon" and one of the following string: + "allwinner,sun8i-h3-system-controller" + "allwinner,sun8i-v3s-system-controller" + "allwinner,sun50i-a64-system-controller" + "allwinner,sun8i-a83t-system-controller" + +Example: +syscon: syscon@1c00000 { + compatible = "allwinner,sun8i-h3-system-controller", "syscon"; + reg = <0x01c00000 0x1000>; +}; diff --git a/Documentation/devicetree/bindings/mmc/fsl-esdhc.txt b/Documentation/devicetree/bindings/mmc/fsl-esdhc.txt index dedfb02c744a..a2cf5e1c87d8 100644 --- a/Documentation/devicetree/bindings/mmc/fsl-esdhc.txt +++ b/Documentation/devicetree/bindings/mmc/fsl-esdhc.txt @@ -7,6 +7,20 @@ This file documents differences between the core properties described by mmc.txt and the properties used by the sdhci-esdhc driver. Required properties: + - compatible : should be "fsl,esdhc", or "fsl,<chip>-esdhc". + Possible compatibles for PowerPC: + "fsl,mpc8536-esdhc" + "fsl,mpc8378-esdhc" + "fsl,p2020-esdhc" + "fsl,p4080-esdhc" + "fsl,t1040-esdhc" + "fsl,t4240-esdhc" + Possible compatibles for ARM: + "fsl,ls1012a-esdhc" + "fsl,ls1088a-esdhc" + "fsl,ls1043a-esdhc" + "fsl,ls1046a-esdhc" + "fsl,ls2080a-esdhc" - interrupt-parent : interrupt source phandle. - clock-frequency : specifies eSDHC base clock frequency. diff --git a/Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt b/Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt index df370585cbcc..8af1afcb86dc 100644 --- a/Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt +++ b/Documentation/devicetree/bindings/mmc/k3-dw-mshc.txt @@ -12,6 +12,7 @@ extensions to the Synopsys Designware Mobile Storage Host Controller. Required Properties: * compatible: should be one of the following. + - "hisilicon,hi3660-dw-mshc": for controllers with hi3660 specific extensions. - "hisilicon,hi4511-dw-mshc": for controllers with hi4511 specific extensions. - "hisilicon,hi6220-dw-mshc": for controllers with hi6220 specific extensions. diff --git a/Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt b/Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt index e25436861867..9029b45b8a22 100644 --- a/Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt +++ b/Documentation/devicetree/bindings/mmc/mmc-pwrseq-simple.txt @@ -18,6 +18,8 @@ Optional properties: "ext_clock" (External clock provided to the card). - post-power-on-delay-ms : Delay in ms after powering the card and de-asserting the reset-gpios (if any) +- power-off-delay-us : Delay in us after asserting the reset-gpios (if any) + during power off of the card. Example: diff --git a/Documentation/devicetree/bindings/mmc/rockchip-dw-mshc.txt b/Documentation/devicetree/bindings/mmc/rockchip-dw-mshc.txt index 520d61dad6dd..49ed3ad2524a 100644 --- a/Documentation/devicetree/bindings/mmc/rockchip-dw-mshc.txt +++ b/Documentation/devicetree/bindings/mmc/rockchip-dw-mshc.txt @@ -15,6 +15,7 @@ Required Properties: - "rockchip,rk3288-dw-mshc": for Rockchip RK3288 - "rockchip,rv1108-dw-mshc", "rockchip,rk3288-dw-mshc": for Rockchip RV1108 - "rockchip,rk3036-dw-mshc", "rockchip,rk3288-dw-mshc": for Rockchip RK3036 + - "rockchip,rk3328-dw-mshc", "rockchip,rk3288-dw-mshc": for Rockchip RK3328 - "rockchip,rk3368-dw-mshc", "rockchip,rk3288-dw-mshc": for Rockchip RK3368 - "rockchip,rk3399-dw-mshc", "rockchip,rk3288-dw-mshc": for Rockchip RK3399 @@ -31,6 +32,10 @@ Optional Properties: probing, low speeds or in case where all phases work at tuning time. If not specified 0 deg will be used. +* rockchip,desired-num-phases: The desired number of times that the host + execute tuning when needed. If not specified, the host will do tuning + for 360 times, namely tuning for each degree. + Example: rkdwmmc0@12200000 { diff --git a/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt b/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt index 74166a0d460d..0e026c151c1c 100644 --- a/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt +++ b/Documentation/devicetree/bindings/mmc/ti-omap-hsmmc.txt @@ -18,7 +18,7 @@ Required properties: Optional properties: ti,dual-volt: boolean, supports dual voltage cards <supply-name>-supply: phandle to the regulator device tree node -"supply-name" examples are "vmmc", "vmmc_aux" etc +"supply-name" examples are "vmmc", "vmmc_aux"(deprecated)/"vqmmc" etc ti,non-removable: non-removable slot (like eMMC) ti,needs-special-reset: Requires a special softreset sequence ti,needs-special-hs-handling: HSMMC IP needs special setting for handling High Speed diff --git a/Documentation/devicetree/bindings/mtd/atmel-nand.txt b/Documentation/devicetree/bindings/mtd/atmel-nand.txt index f6bee57e453a..9bb66e476672 100644 --- a/Documentation/devicetree/bindings/mtd/atmel-nand.txt +++ b/Documentation/devicetree/bindings/mtd/atmel-nand.txt @@ -59,8 +59,22 @@ Required properties: - reg: should contain 2 register ranges. The first one is pointing to the PMECC block, and the second one to the PMECC_ERRLOC block. +* SAMA5 NFC I/O bindings: + +SAMA5 SoCs embed an advanced NAND controller logic to automate READ/WRITE page +operations. This interface to this logic is placed in a separate I/O range and +should thus have its own DT node. + +- compatible: should be "atmel,sama5d3-nfc-io", "syscon". +- reg: should contain the I/O range used to interact with the NFC logic. + Example: + nfc_io: nfc-io@70000000 { + compatible = "atmel,sama5d3-nfc-io", "syscon"; + reg = <0x70000000 0x8000000>; + }; + pmecc: ecc-engine@ffffc070 { compatible = "atmel,at91sam9g45-pmecc"; reg = <0xffffc070 0x490>, diff --git a/Documentation/devicetree/bindings/mux/adi,adg792a.txt b/Documentation/devicetree/bindings/mux/adi,adg792a.txt new file mode 100644 index 000000000000..96b787a69f50 --- /dev/null +++ b/Documentation/devicetree/bindings/mux/adi,adg792a.txt @@ -0,0 +1,75 @@ +Bindings for Analog Devices ADG792A/G Triple 4:1 Multiplexers + +Required properties: +- compatible : "adi,adg792a" or "adi,adg792g" +- #mux-control-cells : <0> if parallel (the three muxes are bound together + with a single mux controller controlling all three muxes), or <1> if + not (one mux controller for each mux). +* Standard mux-controller bindings as described in mux-controller.txt + +Optional properties for ADG792G: +- gpio-controller : if present, #gpio-cells below is required. +- #gpio-cells : should be <2> + - First cell is the GPO line number, i.e. 0 or 1 + - Second cell is used to specify active high (0) + or active low (1) + +Optional properties: +- idle-state : if present, array of states that the mux controllers will have + when idle. The special state MUX_IDLE_AS_IS is the default and + MUX_IDLE_DISCONNECT is also supported. + +States 0 through 3 correspond to signals A through D in the datasheet. + +Example: + + /* + * Three independent mux controllers (of which one is used). + * Mux 0 is disconnected when idle, mux 1 idles in the previously + * selected state and mux 2 idles with signal B. + */ + &i2c0 { + mux: mux-controller@50 { + compatible = "adi,adg792a"; + reg = <0x50>; + #mux-control-cells = <1>; + + idle-state = <MUX_IDLE_DISCONNECT MUX_IDLE_AS_IS 1>; + }; + }; + + adc-mux { + compatible = "io-channel-mux"; + io-channels = <&adc 0>; + io-channel-names = "parent"; + + mux-controls = <&mux 2>; + + channels = "sync-1", "", "out"; + }; + + + /* + * Three parallel muxes with one mux controller, useful e.g. if + * the adc is differential, thus needing two signals to be muxed + * simultaneously for correct operation. + */ + &i2c0 { + pmux: mux-controller@50 { + compatible = "adi,adg792a"; + reg = <0x50>; + #mux-control-cells = <0>; + + idle-state = <1>; + }; + }; + + diff-adc-mux { + compatible = "io-channel-mux"; + io-channels = <&adc 0>; + io-channel-names = "parent"; + + mux-controls = <&pmux>; + + channels = "sync-1", "", "out"; + }; diff --git a/Documentation/devicetree/bindings/mux/gpio-mux.txt b/Documentation/devicetree/bindings/mux/gpio-mux.txt new file mode 100644 index 000000000000..b8f746344d80 --- /dev/null +++ b/Documentation/devicetree/bindings/mux/gpio-mux.txt @@ -0,0 +1,69 @@ +GPIO-based multiplexer controller bindings + +Define what GPIO pins are used to control a multiplexer. Or several +multiplexers, if the same pins control more than one multiplexer. + +Required properties: +- compatible : "gpio-mux" +- mux-gpios : list of gpios used to control the multiplexer, least + significant bit first. +- #mux-control-cells : <0> +* Standard mux-controller bindings as decribed in mux-controller.txt + +Optional properties: +- idle-state : if present, the state the mux will have when idle. The + special state MUX_IDLE_AS_IS is the default. + +The multiplexer state is defined as the number represented by the +multiplexer GPIO pins, where the first pin is the least significant +bit. An active pin is a binary 1, an inactive pin is a binary 0. + +Example: + + mux: mux-controller { + compatible = "gpio-mux"; + #mux-control-cells = <0>; + + mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>, + <&pioA 1 GPIO_ACTIVE_HIGH>; + }; + + adc-mux { + compatible = "io-channel-mux"; + io-channels = <&adc 0>; + io-channel-names = "parent"; + + mux-controls = <&mux>; + + channels = "sync-1", "in", "out", "sync-2"; + }; + + i2c-mux { + compatible = "i2c-mux"; + i2c-parent = <&i2c1>; + + mux-controls = <&mux>; + + #address-cells = <1>; + #size-cells = <0>; + + i2c@0 { + reg = <0>; + #address-cells = <1>; + #size-cells = <0>; + + ssd1307: oled@3c { + /* ... */ + }; + }; + + i2c@3 { + reg = <3>; + #address-cells = <1>; + #size-cells = <0>; + + pca9555: pca9555@20 { + /* ... */ + }; + }; + }; diff --git a/Documentation/devicetree/bindings/mux/mmio-mux.txt b/Documentation/devicetree/bindings/mux/mmio-mux.txt new file mode 100644 index 000000000000..a9bfb4d8b6ac --- /dev/null +++ b/Documentation/devicetree/bindings/mux/mmio-mux.txt @@ -0,0 +1,60 @@ +MMIO register bitfield-based multiplexer controller bindings + +Define register bitfields to be used to control multiplexers. The parent +device tree node must be a syscon node to provide register access. + +Required properties: +- compatible : "mmio-mux" +- #mux-control-cells : <1> +- mux-reg-masks : an array of register offset and pre-shifted bitfield mask + pairs, each describing a single mux control. +* Standard mux-controller bindings as decribed in mux-controller.txt + +Optional properties: +- idle-states : if present, the state the muxes will have when idle. The + special state MUX_IDLE_AS_IS is the default. + +The multiplexer state of each multiplexer is defined as the value of the +bitfield described by the corresponding register offset and bitfield mask pair +in the mux-reg-masks array, accessed through the parent syscon. + +Example: + + syscon { + compatible = "syscon"; + + mux: mux-controller { + compatible = "mmio-mux"; + #mux-control-cells = <1>; + + mux-reg-masks = <0x3 0x30>, /* 0: reg 0x3, bits 5:4 */ + <0x3 0x40>, /* 1: reg 0x3, bit 6 */ + idle-states = <MUX_IDLE_AS_IS>, <0>; + }; + }; + + video-mux { + compatible = "video-mux"; + mux-controls = <&mux 0>; + + ports { + /* inputs 0..3 */ + port@0 { + reg = <0>; + }; + port@1 { + reg = <1>; + }; + port@2 { + reg = <2>; + }; + port@3 { + reg = <3>; + }; + + /* output */ + port@4 { + reg = <4>; + }; + }; + }; diff --git a/Documentation/devicetree/bindings/mux/mux-controller.txt b/Documentation/devicetree/bindings/mux/mux-controller.txt new file mode 100644 index 000000000000..4f47e4bd2fa0 --- /dev/null +++ b/Documentation/devicetree/bindings/mux/mux-controller.txt @@ -0,0 +1,157 @@ +Common multiplexer controller bindings +====================================== + +A multiplexer (or mux) controller will have one, or several, consumer devices +that uses the mux controller. Thus, a mux controller can possibly control +several parallel multiplexers. Presumably there will be at least one +multiplexer needed by each consumer, but a single mux controller can of course +control several multiplexers for a single consumer. + +A mux controller provides a number of states to its consumers, and the state +space is a simple zero-based enumeration. I.e. 0-1 for a 2-way multiplexer, +0-7 for an 8-way multiplexer, etc. + + +Consumers +--------- + +Mux controller consumers should specify a list of mux controllers that they +want to use with a property containing a 'mux-ctrl-list': + + mux-ctrl-list ::= <single-mux-ctrl> [mux-ctrl-list] + single-mux-ctrl ::= <mux-ctrl-phandle> [mux-ctrl-specifier] + mux-ctrl-phandle : phandle to mux controller node + mux-ctrl-specifier : array of #mux-control-cells specifying the + given mux controller (controller specific) + +Mux controller properties should be named "mux-controls". The exact meaning of +each mux controller property must be documented in the device tree binding for +each consumer. An optional property "mux-control-names" may contain a list of +strings to label each of the mux controllers listed in the "mux-controls" +property. + +Drivers for devices that use more than a single mux controller can use the +"mux-control-names" property to map the name of the requested mux controller +to an index into the list given by the "mux-controls" property. + +mux-ctrl-specifier typically encodes the chip-relative mux controller number. +If the mux controller chip only provides a single mux controller, the +mux-ctrl-specifier can typically be left out. + +Example: + + /* One consumer of a 2-way mux controller (one GPIO-line) */ + mux: mux-controller { + compatible = "gpio-mux"; + #mux-control-cells = <0>; + + mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>; + }; + + adc-mux { + compatible = "io-channel-mux"; + io-channels = <&adc 0>; + io-channel-names = "parent"; + + mux-controls = <&mux>; + mux-control-names = "adc"; + + channels = "sync", "in"; + }; + +Note that in the example above, specifying the "mux-control-names" is redundant +because there is only one mux controller in the list. However, if the driver +for the consumer node in fact asks for a named mux controller, that name is of +course still required. + + /* + * Two consumers (one for an ADC line and one for an i2c bus) of + * parallel 4-way multiplexers controlled by the same two GPIO-lines. + */ + mux: mux-controller { + compatible = "gpio-mux"; + #mux-control-cells = <0>; + + mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>, + <&pioA 1 GPIO_ACTIVE_HIGH>; + }; + + adc-mux { + compatible = "io-channel-mux"; + io-channels = <&adc 0>; + io-channel-names = "parent"; + + mux-controls = <&mux>; + + channels = "sync-1", "in", "out", "sync-2"; + }; + + i2c-mux { + compatible = "i2c-mux"; + i2c-parent = <&i2c1>; + + mux-controls = <&mux>; + + #address-cells = <1>; + #size-cells = <0>; + + i2c@0 { + reg = <0>; + #address-cells = <1>; + #size-cells = <0>; + + ssd1307: oled@3c { + /* ... */ + }; + }; + + i2c@3 { + reg = <3>; + #address-cells = <1>; + #size-cells = <0>; + + pca9555: pca9555@20 { + /* ... */ + }; + }; + }; + + +Mux controller nodes +-------------------- + +Mux controller nodes must specify the number of cells used for the +specifier using the '#mux-control-cells' property. + +Optionally, mux controller nodes can also specify the state the mux should +have when it is idle. The idle-state property is used for this. If the +idle-state is not present, the mux controller is typically left as is when +it is idle. For multiplexer chips that expose several mux controllers, the +idle-state property is an array with one idle state for each mux controller. + +The special value (-1) may be used to indicate that the mux should be left +as is when it is idle. This is the default, but can still be useful for +mux controller chips with more than one mux controller, particularly when +there is a need to "step past" a mux controller and set some other idle +state for a mux controller with a higher index. + +Some mux controllers have the ability to disconnect the input/output of the +multiplexer. Using this disconnected high-impedance state as the idle state +is indicated with idle state (-2). + +These constants are available in + + #include <dt-bindings/mux/mux.h> + +as MUX_IDLE_AS_IS (-1) and MUX_IDLE_DISCONNECT (-2). + +An example mux controller node look like this (the adg972a chip is a triple +4-way multiplexer): + + mux: mux-controller@50 { + compatible = "adi,adg792a"; + reg = <0x50>; + #mux-control-cells = <1>; + + idle-state = <MUX_IDLE_DISCONNECT MUX_IDLE_AS_IS 2>; + }; diff --git a/Documentation/devicetree/bindings/net/cortina.txt b/Documentation/devicetree/bindings/net/cortina.txt new file mode 100644 index 000000000000..40d0bd984113 --- /dev/null +++ b/Documentation/devicetree/bindings/net/cortina.txt @@ -0,0 +1,21 @@ +Cortina Phy Driver Device Tree Bindings +--------------------------------------- + +CORTINA is a registered trademark of Cortina Systems, Inc. + +The driver supports the Cortina Electronic Dispersion Compensation (EDC) +devices, equipped with clock and data recovery (CDR) circuits. These +devices make use of registers that are not compatible with Clause 45 or +Clause 22, therefore they need to be described using the +"ethernet-phy-id" compatible. + +Since the driver only implements polling mode support, interrupts info +can be skipped. + +Example (CS4340 phy): + mdio { + cs4340_phy@10 { + compatible = "ethernet-phy-id13e5.1002"; + reg = <0x10>; + }; + }; diff --git a/Documentation/devicetree/bindings/net/dsa/b53.txt b/Documentation/devicetree/bindings/net/dsa/b53.txt index d6c6e41648d4..8acf51a4dfa8 100644 --- a/Documentation/devicetree/bindings/net/dsa/b53.txt +++ b/Documentation/devicetree/bindings/net/dsa/b53.txt @@ -13,6 +13,9 @@ Required properties: "brcm,bcm5397" "brcm,bcm5398" + For the BCM11360 SoC, must be: + "brcm,bcm11360-srab" and the mandatory "brcm,cygnus-srab" string + For the BCM5310x SoCs with an integrated switch, must be one of: "brcm,bcm53010-srab" "brcm,bcm53011-srab" @@ -34,7 +37,7 @@ Required properties: "brcm,bcm6328-switch" "brcm,bcm6368-switch" and the mandatory "brcm,bcm63xx-switch" -See Documentation/devicetree/bindings/dsa/dsa.txt for a list of additional +See Documentation/devicetree/bindings/net/dsa/dsa.txt for a list of additional required and optional properties. Examples: diff --git a/Documentation/devicetree/bindings/net/dsa/ksz.txt b/Documentation/devicetree/bindings/net/dsa/ksz.txt new file mode 100644 index 000000000000..0ab8b39d0b30 --- /dev/null +++ b/Documentation/devicetree/bindings/net/dsa/ksz.txt @@ -0,0 +1,72 @@ +Microchip KSZ Series Ethernet switches +================================== + +Required properties: + +- compatible: For external switch chips, compatible string must be exactly one + of: "microchip,ksz9477" + +See Documentation/devicetree/bindings/dsa/dsa.txt for a list of additional +required and optional properties. + +Examples: + +Ethernet switch connected via SPI to the host, CPU port wired to eth0: + + eth0: ethernet@10001000 { + fixed-link { + speed = <1000>; + full-duplex; + }; + }; + + spi1: spi@f8008000 { + pinctrl-0 = <&pinctrl_spi_ksz>; + cs-gpios = <&pioC 25 0>; + id = <1>; + status = "okay"; + + ksz9477: ksz9477@0 { + compatible = "microchip,ksz9477"; + reg = <0>; + + spi-max-frequency = <44000000>; + spi-cpha; + spi-cpol; + + status = "okay"; + ports { + #address-cells = <1>; + #size-cells = <0>; + port@0 { + reg = <0>; + label = "lan1"; + }; + port@1 { + reg = <1>; + label = "lan2"; + }; + port@2 { + reg = <2>; + label = "lan3"; + }; + port@3 { + reg = <3>; + label = "lan4"; + }; + port@4 { + reg = <4>; + label = "lan5"; + }; + port@5 { + reg = <5>; + label = "cpu"; + ethernet = <ð0>; + fixed-link { + speed = <1000>; + full-duplex; + }; + }; + }; + }; + }; diff --git a/Documentation/devicetree/bindings/net/dsa/marvell.txt b/Documentation/devicetree/bindings/net/dsa/marvell.txt index 7ef9dbb08957..1d4d0f49c9d0 100644 --- a/Documentation/devicetree/bindings/net/dsa/marvell.txt +++ b/Documentation/devicetree/bindings/net/dsa/marvell.txt @@ -26,6 +26,10 @@ Optional properties: - interrupt-controller : Indicates the switch is itself an interrupt controller. This is used for the PHY interrupts. #interrupt-cells = <2> : Controller uses two cells, number and flag +- eeprom-length : Set to the length of an EEPROM connected to the + switch. Must be set if the switch can not detect + the presence and/or size of a connected EEPROM, + otherwise optional. - mdio : Container of PHY and devices on the switches MDIO bus. - mdio? : Container of PHYs and devices on the external MDIO diff --git a/Documentation/devicetree/bindings/net/dwmac-sun8i.txt b/Documentation/devicetree/bindings/net/dwmac-sun8i.txt new file mode 100644 index 000000000000..725f3b187886 --- /dev/null +++ b/Documentation/devicetree/bindings/net/dwmac-sun8i.txt @@ -0,0 +1,84 @@ +* Allwinner sun8i GMAC ethernet controller + +This device is a platform glue layer for stmmac. +Please see stmmac.txt for the other unchanged properties. + +Required properties: +- compatible: should be one of the following string: + "allwinner,sun8i-a83t-emac" + "allwinner,sun8i-h3-emac" + "allwinner,sun8i-v3s-emac" + "allwinner,sun50i-a64-emac" +- reg: address and length of the register for the device. +- interrupts: interrupt for the device +- interrupt-names: should be "macirq" +- clocks: A phandle to the reference clock for this device +- clock-names: should be "stmmaceth" +- resets: A phandle to the reset control for this device +- reset-names: should be "stmmaceth" +- phy-mode: See ethernet.txt +- phy-handle: See ethernet.txt +- #address-cells: shall be 1 +- #size-cells: shall be 0 +- syscon: A phandle to the syscon of the SoC with one of the following + compatible string: + - allwinner,sun8i-h3-system-controller + - allwinner,sun8i-v3s-system-controller + - allwinner,sun50i-a64-system-controller + - allwinner,sun8i-a83t-system-controller + +Optional properties: +- allwinner,tx-delay-ps: TX clock delay chain value in ps. Range value is 0-700. Default is 0) +- allwinner,rx-delay-ps: RX clock delay chain value in ps. Range value is 0-3100. Default is 0) +Both delay properties need to be a multiple of 100. They control the delay for +external PHY. + +Optional properties for the following compatibles: + - "allwinner,sun8i-h3-emac", + - "allwinner,sun8i-v3s-emac": +- allwinner,leds-active-low: EPHY LEDs are active low + +Required child node of emac: +- mdio bus node: should be named mdio + +Required properties of the mdio node: +- #address-cells: shall be 1 +- #size-cells: shall be 0 + +The device node referenced by "phy" or "phy-handle" should be a child node +of the mdio node. See phy.txt for the generic PHY bindings. + +Required properties of the phy node with the following compatibles: + - "allwinner,sun8i-h3-emac", + - "allwinner,sun8i-v3s-emac": +- clocks: a phandle to the reference clock for the EPHY +- resets: a phandle to the reset control for the EPHY + +Example: + +emac: ethernet@1c0b000 { + compatible = "allwinner,sun8i-h3-emac"; + syscon = <&syscon>; + reg = <0x01c0b000 0x104>; + interrupts = <GIC_SPI 82 IRQ_TYPE_LEVEL_HIGH>; + interrupt-names = "macirq"; + resets = <&ccu RST_BUS_EMAC>; + reset-names = "stmmaceth"; + clocks = <&ccu CLK_BUS_EMAC>; + clock-names = "stmmaceth"; + #address-cells = <1>; + #size-cells = <0>; + + phy-handle = <&int_mii_phy>; + phy-mode = "mii"; + allwinner,leds-active-low; + mdio: mdio { + #address-cells = <1>; + #size-cells = <0>; + int_mii_phy: ethernet-phy@1 { + reg = <1>; + clocks = <&ccu CLK_BUS_EPHY>; + resets = <&ccu RST_BUS_EPHY>; + }; + }; +}; diff --git a/Documentation/devicetree/bindings/net/ethernet.txt b/Documentation/devicetree/bindings/net/ethernet.txt index 3a6916909d90..edd7fd2bbbf9 100644 --- a/Documentation/devicetree/bindings/net/ethernet.txt +++ b/Documentation/devicetree/bindings/net/ethernet.txt @@ -11,6 +11,7 @@ The following properties are common to the Ethernet controllers: the maximum frame size (there's contradiction in ePAPR). - phy-mode: string, operation mode of the PHY interface. This is now a de-facto standard property; supported values are: + * "internal" * "mii" * "gmii" * "sgmii" @@ -32,6 +33,8 @@ The following properties are common to the Ethernet controllers: * "2000base-x", * "2500base-x", * "rxaui" + * "xaui" + * "10gbase-kr" (10GBASE-KR, XFI, SFI) - phy-connection-type: the same as "phy-mode" property but described in ePAPR; - phy-handle: phandle, specifies a reference to a node representing a PHY device; this property is described in ePAPR and so preferred; diff --git a/Documentation/devicetree/bindings/net/fsl-fec.txt b/Documentation/devicetree/bindings/net/fsl-fec.txt index a1e3693cca16..6f55bdd52f8a 100644 --- a/Documentation/devicetree/bindings/net/fsl-fec.txt +++ b/Documentation/devicetree/bindings/net/fsl-fec.txt @@ -15,6 +15,10 @@ Optional properties: - phy-reset-active-high : If present then the reset sequence using the GPIO specified in the "phy-reset-gpios" property is reversed (H=reset state, L=operation state). +- phy-reset-post-delay : Post reset delay in milliseconds. If present then + a delay of phy-reset-post-delay milliseconds will be observed after the + phy-reset-gpios has been toggled. Can be omitted thus no delay is + observed. Delay is in range of 1ms to 1000ms. Other delays are invalid. - phy-supply : regulator that powers the Ethernet PHY. - phy-handle : phandle to the PHY device connected to this device. - fixed-link : Assume a fixed link. See fixed-link.txt in the same directory. diff --git a/Documentation/devicetree/bindings/net/macb.txt b/Documentation/devicetree/bindings/net/macb.txt index 1506e948610c..27966ae741e0 100644 --- a/Documentation/devicetree/bindings/net/macb.txt +++ b/Documentation/devicetree/bindings/net/macb.txt @@ -22,6 +22,7 @@ Required properties: Required elements: 'pclk', 'hclk' Optional elements: 'tx_clk' Optional elements: 'rx_clk' applies to cdns,zynqmp-gem + Optional elements: 'tsu_clk' - clocks: Phandles to input clocks. Optional properties for PHY child node: diff --git a/Documentation/devicetree/bindings/net/marvell-orion-mdio.txt b/Documentation/devicetree/bindings/net/marvell-orion-mdio.txt index ccdabdcc8618..42cd81090a2c 100644 --- a/Documentation/devicetree/bindings/net/marvell-orion-mdio.txt +++ b/Documentation/devicetree/bindings/net/marvell-orion-mdio.txt @@ -1,12 +1,14 @@ * Marvell MDIO Ethernet Controller interface The Ethernet controllers of the Marvel Kirkwood, Dove, Orion5x, -MV78xx0, Armada 370 and Armada XP have an identical unit that provides -an interface with the MDIO bus. This driver handles this MDIO -interface. +MV78xx0, Armada 370, Armada XP, Armada 7k and Armada 8k have an +identical unit that provides an interface with the MDIO bus. +Additionally, Armada 7k and Armada 8k has a second unit which +provides an interface with the xMDIO bus. This driver handles +these interfaces. Required properties: -- compatible: "marvell,orion-mdio" +- compatible: "marvell,orion-mdio" or "marvell,xmdio" - reg: address and length of the MDIO registers. When an interrupt is not present, the length is the size of the SMI register (4 bytes) otherwise it must be 0x84 bytes to cover the interrupt control diff --git a/Documentation/devicetree/bindings/net/nfc/trf7970a.txt b/Documentation/devicetree/bindings/net/nfc/trf7970a.txt index c627bbb3009e..60c833d62181 100644 --- a/Documentation/devicetree/bindings/net/nfc/trf7970a.txt +++ b/Documentation/devicetree/bindings/net/nfc/trf7970a.txt @@ -13,14 +13,10 @@ Optional SoC Specific Properties: - pinctrl-names: Contains only one value - "default". - pintctrl-0: Specifies the pin control groups used for this controller. - autosuspend-delay: Specify autosuspend delay in milliseconds. -- vin-voltage-override: Specify voltage of VIN pin in microvolts. - irq-status-read-quirk: Specify that the trf7970a being used has the "IRQ Status Read" erratum. - en2-rf-quirk: Specify that the trf7970a being used has the "EN2 RF" erratum. -- t5t-rmb-extra-byte-quirk: Specify that the trf7970a has the erratum - where an extra byte is returned by Read Multiple Block commands issued - to Type 5 tags. - vdd-io-supply: Regulator specifying voltage for vdd-io - clock-frequency: Set to specify that the input frequency to the trf7970a is 13560000Hz or 27120000Hz @@ -37,15 +33,13 @@ Example (for ARM-based BeagleBone with TRF7970A on SPI1): spi-max-frequency = <2000000>; interrupt-parent = <&gpio2>; interrupts = <14 0>; - ti,enable-gpios = <&gpio2 2 GPIO_ACTIVE_LOW>, - <&gpio2 5 GPIO_ACTIVE_LOW>; + ti,enable-gpios = <&gpio2 2 GPIO_ACTIVE_HIGH>, + <&gpio2 5 GPIO_ACTIVE_HIGH>; vin-supply = <&ldo3_reg>; - vin-voltage-override = <5000000>; vdd-io-supply = <&ldo2_reg>; autosuspend-delay = <30000>; irq-status-read-quirk; en2-rf-quirk; - t5t-rmb-extra-byte-quirk; clock-frequency = <27120000>; status = "okay"; }; diff --git a/Documentation/devicetree/bindings/net/qca,qca7000.txt b/Documentation/devicetree/bindings/net/qca,qca7000.txt new file mode 100644 index 000000000000..6d9efb2eb9a5 --- /dev/null +++ b/Documentation/devicetree/bindings/net/qca,qca7000.txt @@ -0,0 +1,88 @@ +* Qualcomm QCA7000 + +The QCA7000 is a serial-to-powerline bridge with a host interface which could +be configured either as SPI or UART slave. This configuration is done by +the QCA7000 firmware. + +(a) Ethernet over SPI + +In order to use the QCA7000 as SPI device it must be defined as a child of a +SPI master in the device tree. + +Required properties: +- compatible : Should be "qca,qca7000" +- reg : Should specify the SPI chip select +- interrupts : The first cell should specify the index of the source + interrupt and the second cell should specify the trigger + type as rising edge +- spi-cpha : Must be set +- spi-cpol : Must be set + +Optional properties: +- interrupt-parent : Specify the pHandle of the source interrupt +- spi-max-frequency : Maximum frequency of the SPI bus the chip can operate at. + Numbers smaller than 1000000 or greater than 16000000 + are invalid. Missing the property will set the SPI + frequency to 8000000 Hertz. +- local-mac-address : see ./ethernet.txt +- qca,legacy-mode : Set the SPI data transfer of the QCA7000 to legacy mode. + In this mode the SPI master must toggle the chip select + between each data word. In burst mode these gaps aren't + necessary, which is faster. This setting depends on how + the QCA7000 is setup via GPIO pin strapping. If the + property is missing the driver defaults to burst mode. + +SPI Example: + +/* Freescale i.MX28 SPI master*/ +ssp2: spi@80014000 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "fsl,imx28-spi"; + pinctrl-names = "default"; + pinctrl-0 = <&spi2_pins_a>; + status = "okay"; + + qca7000: ethernet@0 { + compatible = "qca,qca7000"; + reg = <0x0>; + interrupt-parent = <&gpio3>; /* GPIO Bank 3 */ + interrupts = <25 0x1>; /* Index: 25, rising edge */ + spi-cpha; /* SPI mode: CPHA=1 */ + spi-cpol; /* SPI mode: CPOL=1 */ + spi-max-frequency = <8000000>; /* freq: 8 MHz */ + local-mac-address = [ A0 B0 C0 D0 E0 F0 ]; + }; +}; + +(b) Ethernet over UART + +In order to use the QCA7000 as UART slave it must be defined as a child of a +UART master in the device tree. It is possible to preconfigure the UART +settings of the QCA7000 firmware, but it's not possible to change them during +runtime. + +Required properties: +- compatible : Should be "qca,qca7000" + +Optional properties: +- local-mac-address : see ./ethernet.txt +- current-speed : current baud rate of QCA7000 which defaults to 115200 + if absent, see also ../serial/slave-device.txt + +UART Example: + +/* Freescale i.MX28 UART */ +auart0: serial@8006a000 { + compatible = "fsl,imx28-auart", "fsl,imx23-auart"; + reg = <0x8006a000 0x2000>; + pinctrl-names = "default"; + pinctrl-0 = <&auart0_2pins_a>; + status = "okay"; + + qca7000: ethernet { + compatible = "qca,qca7000"; + local-mac-address = [ A0 B0 C0 D0 E0 F0 ]; + current-speed = <38400>; + }; +}; diff --git a/Documentation/devicetree/bindings/net/qca-qca7000-spi.txt b/Documentation/devicetree/bindings/net/qca-qca7000-spi.txt deleted file mode 100644 index c74989c0d8ac..000000000000 --- a/Documentation/devicetree/bindings/net/qca-qca7000-spi.txt +++ /dev/null @@ -1,47 +0,0 @@ -* Qualcomm QCA7000 (Ethernet over SPI protocol) - -Note: The QCA7000 is useable as a SPI device. In this case it must be defined -as a child of a SPI master in the device tree. - -Required properties: -- compatible : Should be "qca,qca7000" -- reg : Should specify the SPI chip select -- interrupts : The first cell should specify the index of the source interrupt - and the second cell should specify the trigger type as rising edge -- spi-cpha : Must be set -- spi-cpol: Must be set - -Optional properties: -- interrupt-parent : Specify the pHandle of the source interrupt -- spi-max-frequency : Maximum frequency of the SPI bus the chip can operate at. - Numbers smaller than 1000000 or greater than 16000000 are invalid. Missing - the property will set the SPI frequency to 8000000 Hertz. -- local-mac-address: 6 bytes, MAC address -- qca,legacy-mode : Set the SPI data transfer of the QCA7000 to legacy mode. - In this mode the SPI master must toggle the chip select between each data - word. In burst mode these gaps aren't necessary, which is faster. - This setting depends on how the QCA7000 is setup via GPIO pin strapping. - If the property is missing the driver defaults to burst mode. - -Example: - -/* Freescale i.MX28 SPI master*/ -ssp2: spi@80014000 { - #address-cells = <1>; - #size-cells = <0>; - compatible = "fsl,imx28-spi"; - pinctrl-names = "default"; - pinctrl-0 = <&spi2_pins_a>; - status = "okay"; - - qca7000: ethernet@0 { - compatible = "qca,qca7000"; - reg = <0x0>; - interrupt-parent = <&gpio3>; /* GPIO Bank 3 */ - interrupts = <25 0x1>; /* Index: 25, rising edge */ - spi-cpha; /* SPI mode: CPHA=1 */ - spi-cpol; /* SPI mode: CPOL=1 */ - spi-max-frequency = <8000000>; /* freq: 8 MHz */ - local-mac-address = [ A0 B0 C0 D0 E0 F0 ]; - }; -}; diff --git a/Documentation/devicetree/bindings/net/smsc911x.txt b/Documentation/devicetree/bindings/net/smsc911x.txt index 16c3a9501f5d..acfafc8e143c 100644 --- a/Documentation/devicetree/bindings/net/smsc911x.txt +++ b/Documentation/devicetree/bindings/net/smsc911x.txt @@ -27,6 +27,7 @@ Optional properties: of the device. On many systems this is wired high so the device goes out of reset at power-on, but if it is under program control, this optional GPIO can wake up in response to it. +- vdd33a-supply, vddvario-supply : 3.3V analog and IO logic power supplies Examples: diff --git a/Documentation/devicetree/bindings/net/ti,dp83867.txt b/Documentation/devicetree/bindings/net/ti,dp83867.txt index afe9630a5e7d..02c4353b5cf2 100644 --- a/Documentation/devicetree/bindings/net/ti,dp83867.txt +++ b/Documentation/devicetree/bindings/net/ti,dp83867.txt @@ -18,6 +18,13 @@ Optional property: - ti,max-output-impedance - MAC Interface Impedance control to set the programmable output impedance to maximum value (70 ohms). + - ti,dp83867-rxctrl-strap-quirk - This denotes the fact that the + board has RX_DV/RX_CTRL pin strapped in + mode 1 or 2. To ensure PHY operation, + there are specific actions that + software needs to take when this pin is + strapped in these modes. See data manual + for details. Note: ti,min-output-impedance and ti,max-output-impedance are mutually exclusive. When both properties are present ti,max-output-impedance diff --git a/Documentation/devicetree/bindings/net/ti,wilink-st.txt b/Documentation/devicetree/bindings/net/ti,wilink-st.txt index cbad73a84ac4..1649c1f66b07 100644 --- a/Documentation/devicetree/bindings/net/ti,wilink-st.txt +++ b/Documentation/devicetree/bindings/net/ti,wilink-st.txt @@ -14,6 +14,12 @@ Required properties: - compatible: should be one of the following: "ti,wl1271-st" "ti,wl1273-st" + "ti,wl1281-st" + "ti,wl1283-st" + "ti,wl1285-st" + "ti,wl1801-st" + "ti,wl1805-st" + "ti,wl1807-st" "ti,wl1831-st" "ti,wl1835-st" "ti,wl1837-st" @@ -22,6 +28,10 @@ Optional properties: - enable-gpios : GPIO signal controlling enabling of BT. Active high. - vio-supply : Vio input supply (1.8V) - vbat-supply : Vbat input supply (2.9-4.8V) + - clocks : Must contain an entry, for each entry in clock-names. + See ../clocks/clock-bindings.txt for details. + - clock-names : Must include the following entry: + "ext_clock" (External clock provided to the TI combo chip). Example: @@ -31,5 +41,7 @@ Example: bluetooth { compatible = "ti,wl1835-st"; enable-gpios = <&gpio1 7 GPIO_ACTIVE_HIGH>; + clocks = <&clk32k_wl18xx>; + clock-names = "ext_clock"; }; }; diff --git a/Documentation/devicetree/bindings/net/wireless/ti,wlcore.txt b/Documentation/devicetree/bindings/net/wireless/ti,wlcore.txt index 2a3d90de18ee..7b2cbb14113e 100644 --- a/Documentation/devicetree/bindings/net/wireless/ti,wlcore.txt +++ b/Documentation/devicetree/bindings/net/wireless/ti,wlcore.txt @@ -10,6 +10,7 @@ Required properties: * "ti,wl1273" * "ti,wl1281" * "ti,wl1283" + * "ti,wl1285" * "ti,wl1801" * "ti,wl1805" * "ti,wl1807" diff --git a/Documentation/devicetree/bindings/nvmem/rockchip-efuse.txt b/Documentation/devicetree/bindings/nvmem/rockchip-efuse.txt index 94aeeeabadd5..194926f77194 100644 --- a/Documentation/devicetree/bindings/nvmem/rockchip-efuse.txt +++ b/Documentation/devicetree/bindings/nvmem/rockchip-efuse.txt @@ -4,6 +4,7 @@ Required properties: - compatible: Should be one of the following. - "rockchip,rk3066a-efuse" - for RK3066a SoCs. - "rockchip,rk3188-efuse" - for RK3188 SoCs. + - "rockchip,rk322x-efuse" - for RK322x SoCs. - "rockchip,rk3288-efuse" - for RK3288 SoCs. - "rockchip,rk3399-efuse" - for RK3399 SoCs. - reg: Should contain the registers location and exact eFuse size diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt index 63725498bd20..e36d261b9ba6 100644 --- a/Documentation/devicetree/bindings/opp/opp.txt +++ b/Documentation/devicetree/bindings/opp/opp.txt @@ -186,20 +186,20 @@ Example 1: Single cluster Dual-core ARM cortex A9, switch DVFS states together. compatible = "operating-points-v2"; opp-shared; - opp@1000000000 { + opp-1000000000 { opp-hz = /bits/ 64 <1000000000>; opp-microvolt = <975000 970000 985000>; opp-microamp = <70000>; clock-latency-ns = <300000>; opp-suspend; }; - opp@1100000000 { + opp-1100000000 { opp-hz = /bits/ 64 <1100000000>; opp-microvolt = <1000000 980000 1010000>; opp-microamp = <80000>; clock-latency-ns = <310000>; }; - opp@1200000000 { + opp-1200000000 { opp-hz = /bits/ 64 <1200000000>; opp-microvolt = <1025000>; clock-latency-ns = <290000>; @@ -265,20 +265,20 @@ independently. * independently. */ - opp@1000000000 { + opp-1000000000 { opp-hz = /bits/ 64 <1000000000>; opp-microvolt = <975000 970000 985000>; opp-microamp = <70000>; clock-latency-ns = <300000>; opp-suspend; }; - opp@1100000000 { + opp-1100000000 { opp-hz = /bits/ 64 <1100000000>; opp-microvolt = <1000000 980000 1010000>; opp-microamp = <80000>; clock-latency-ns = <310000>; }; - opp@1200000000 { + opp-1200000000 { opp-hz = /bits/ 64 <1200000000>; opp-microvolt = <1025000>; opp-microamp = <90000; @@ -341,20 +341,20 @@ DVFS state together. compatible = "operating-points-v2"; opp-shared; - opp@1000000000 { + opp-1000000000 { opp-hz = /bits/ 64 <1000000000>; opp-microvolt = <975000 970000 985000>; opp-microamp = <70000>; clock-latency-ns = <300000>; opp-suspend; }; - opp@1100000000 { + opp-1100000000 { opp-hz = /bits/ 64 <1100000000>; opp-microvolt = <1000000 980000 1010000>; opp-microamp = <80000>; clock-latency-ns = <310000>; }; - opp@1200000000 { + opp-1200000000 { opp-hz = /bits/ 64 <1200000000>; opp-microvolt = <1025000>; opp-microamp = <90000>; @@ -367,20 +367,20 @@ DVFS state together. compatible = "operating-points-v2"; opp-shared; - opp@1300000000 { + opp-1300000000 { opp-hz = /bits/ 64 <1300000000>; opp-microvolt = <1050000 1045000 1055000>; opp-microamp = <95000>; clock-latency-ns = <400000>; opp-suspend; }; - opp@1400000000 { + opp-1400000000 { opp-hz = /bits/ 64 <1400000000>; opp-microvolt = <1075000>; opp-microamp = <100000>; clock-latency-ns = <400000>; }; - opp@1500000000 { + opp-1500000000 { opp-hz = /bits/ 64 <1500000000>; opp-microvolt = <1100000 1010000 1110000>; opp-microamp = <95000>; @@ -409,7 +409,7 @@ Example 4: Handling multiple regulators compatible = "operating-points-v2"; opp-shared; - opp@1000000000 { + opp-1000000000 { opp-hz = /bits/ 64 <1000000000>; opp-microvolt = <970000>, /* Supply 0 */ <960000>, /* Supply 1 */ @@ -422,7 +422,7 @@ Example 4: Handling multiple regulators /* OR */ - opp@1000000000 { + opp-1000000000 { opp-hz = /bits/ 64 <1000000000>; opp-microvolt = <975000 970000 985000>, /* Supply 0 */ <965000 960000 975000>, /* Supply 1 */ @@ -435,7 +435,7 @@ Example 4: Handling multiple regulators /* OR */ - opp@1000000000 { + opp-1000000000 { opp-hz = /bits/ 64 <1000000000>; opp-microvolt = <975000 970000 985000>, /* Supply 0 */ <965000 960000 975000>, /* Supply 1 */ @@ -467,7 +467,7 @@ Example 5: opp-supported-hw status = "okay"; opp-shared; - opp@600000000 { + opp-600000000 { /* * Supports all substrate and process versions for 0xF * cuts, i.e. only first four cuts. @@ -478,7 +478,7 @@ Example 5: opp-supported-hw ... }; - opp@800000000 { + opp-800000000 { /* * Supports: * - cuts: only one, 6th cut (represented by 6th bit). @@ -510,7 +510,7 @@ Example 6: opp-microvolt-<name>, opp-microamp-<name>: compatible = "operating-points-v2"; opp-shared; - opp@1000000000 { + opp-1000000000 { opp-hz = /bits/ 64 <1000000000>; opp-microvolt-slow = <915000 900000 925000>; opp-microvolt-fast = <975000 970000 985000>; @@ -518,7 +518,7 @@ Example 6: opp-microvolt-<name>, opp-microamp-<name>: opp-microamp-fast = <71000>; }; - opp@1200000000 { + opp-1200000000 { opp-hz = /bits/ 64 <1200000000>; opp-microvolt-slow = <915000 900000 925000>, /* Supply vcc0 */ <925000 910000 935000>; /* Supply vcc1 */ diff --git a/Documentation/devicetree/bindings/pci/kirin-pcie.txt b/Documentation/devicetree/bindings/pci/kirin-pcie.txt new file mode 100644 index 000000000000..68ffa0fbcd73 --- /dev/null +++ b/Documentation/devicetree/bindings/pci/kirin-pcie.txt @@ -0,0 +1,50 @@ +HiSilicon Kirin SoCs PCIe host DT description + +Kirin PCIe host controller is based on Designware PCI core. +It shares common functions with PCIe Designware core driver +and inherits common properties defined in +Documentation/devicetree/bindings/pci/designware-pci.txt. + +Additional properties are described here: + +Required properties +- compatible: + "hisilicon,kirin960-pcie" for PCIe of Kirin960 SoC +- reg: Should contain rc_dbi, apb, phy, config registers location and length. +- reg-names: Must include the following entries: + "dbi": controller configuration registers; + "apb": apb Ctrl register defined by Kirin; + "phy": apb PHY register defined by Kirin; + "config": PCIe configuration space registers. +- reset-gpios: The gpio to generate PCIe perst assert and deassert signal. + +Optional properties: + +Example based on kirin960: + + pcie@f4000000 { + compatible = "hisilicon,kirin-pcie"; + reg = <0x0 0xf4000000 0x0 0x1000>, <0x0 0xff3fe000 0x0 0x1000>, + <0x0 0xf3f20000 0x0 0x40000>, <0x0 0xF4000000 0 0x2000>; + reg-names = "dbi","apb","phy", "config"; + bus-range = <0x0 0x1>; + #address-cells = <3>; + #size-cells = <2>; + device_type = "pci"; + ranges = <0x02000000 0x0 0x00000000 0x0 0xf5000000 0x0 0x2000000>; + num-lanes = <1>; + #interrupt-cells = <1>; + interrupt-map-mask = <0xf800 0 0 7>; + interrupt-map = <0x0 0 0 1 &gic 0 0 0 282 4>, + <0x0 0 0 2 &gic 0 0 0 283 4>, + <0x0 0 0 3 &gic 0 0 0 284 4>, + <0x0 0 0 4 &gic 0 0 0 285 4>; + clocks = <&crg_ctrl HI3660_PCIEPHY_REF>, + <&crg_ctrl HI3660_CLK_GATE_PCIEAUX>, + <&crg_ctrl HI3660_PCLK_GATE_PCIE_PHY>, + <&crg_ctrl HI3660_PCLK_GATE_PCIE_SYS>, + <&crg_ctrl HI3660_ACLK_GATE_PCIE>; + clock-names = "pcie_phy_ref", "pcie_aux", + "pcie_apb_phy", "pcie_apb_sys", "pcie_aclk"; + reset-gpios = <&gpio11 1 0 >; + }; diff --git a/Documentation/devicetree/bindings/phy/bcm-ns-usb3-phy.txt b/Documentation/devicetree/bindings/phy/bcm-ns-usb3-phy.txt index 09aeba94538d..32f057260351 100644 --- a/Documentation/devicetree/bindings/phy/bcm-ns-usb3-phy.txt +++ b/Documentation/devicetree/bindings/phy/bcm-ns-usb3-phy.txt @@ -3,9 +3,10 @@ Driver for Broadcom Northstar USB 3.0 PHY Required properties: - compatible: one of: "brcm,ns-ax-usb3-phy", "brcm,ns-bx-usb3-phy". -- reg: register mappings for DMP (Device Management Plugin) and ChipCommon B - MMI. -- reg-names: "dmp" and "ccb-mii" +- reg: address of MDIO bus device +- usb3-dmp-syscon: phandle to syscon with DMP (Device Management Plugin) + registers +- #phy-cells: must be 0 Initialization of USB 3.0 PHY depends on Northstar version. There are currently three known series: Ax, Bx and Cx. @@ -15,9 +16,19 @@ Known B1: BCM4707 rev 6 Known C0: BCM47094 rev 0 Example: - usb3-phy { - compatible = "brcm,ns-ax-usb3-phy"; - reg = <0x18105000 0x1000>, <0x18003000 0x1000>; - reg-names = "dmp", "ccb-mii"; - #phy-cells = <0>; + mdio: mdio@0 { + reg = <0x0>; + #size-cells = <1>; + #address-cells = <0>; + + usb3-phy@10 { + compatible = "brcm,ns-ax-usb3-phy"; + reg = <0x10>; + usb3-dmp-syscon = <&usb3_dmp>; + #phy-cells = <0>; + }; + }; + + usb3_dmp: syscon@18105000 { + reg = <0x18105000 0x1000>; }; diff --git a/Documentation/devicetree/bindings/phy/brcm,ns2-drd-phy.txt b/Documentation/devicetree/bindings/phy/brcm,ns2-drd-phy.txt new file mode 100644 index 000000000000..04f063aa7883 --- /dev/null +++ b/Documentation/devicetree/bindings/phy/brcm,ns2-drd-phy.txt @@ -0,0 +1,30 @@ +BROADCOM NORTHSTAR2 USB2 (DUAL ROLE DEVICE) PHY + +Required properties: + - compatible: brcm,ns2-drd-phy + - reg: offset and length of the NS2 PHY related registers. + - reg-names + The below registers must be provided. + icfg - for DRD ICFG configurations + rst-ctrl - for DRD IDM reset + crmu-ctrl - for CRMU core vdd, PHY and PHY PLL reset + usb2-strap - for port over current polarity reversal + - #phy-cells: Must be 0. No args required. + - vbus-gpios: vbus gpio binding + - id-gpios: id gpio binding + +Refer to phy/phy-bindings.txt for the generic PHY binding properties + +Example: + usbdrd_phy: phy@66000960 { + #phy-cells = <0>; + compatible = "brcm,ns2-drd-phy"; + reg = <0x66000960 0x24>, + <0x67012800 0x4>, + <0x6501d148 0x4>, + <0x664d0700 0x4>; + reg-names = "icfg", "rst-ctrl", + "crmu-ctrl", "usb2-strap"; + id-gpios = <&gpio_g 30 0>; + vbus-gpios = <&gpio_g 31 0>; + }; diff --git a/Documentation/devicetree/bindings/phy/brcm-sata-phy.txt b/Documentation/devicetree/bindings/phy/brcm-sata-phy.txt index 6ccce09d8bbf..97977cd29a98 100644 --- a/Documentation/devicetree/bindings/phy/brcm-sata-phy.txt +++ b/Documentation/devicetree/bindings/phy/brcm-sata-phy.txt @@ -7,12 +7,13 @@ Required properties: "brcm,iproc-ns2-sata-phy" "brcm,iproc-nsp-sata-phy" "brcm,phy-sata3" + "brcm,iproc-sr-sata-phy" - address-cells: should be 1 - size-cells: should be 0 - reg: register ranges for the PHY PCB interface - reg-names: should be "phy" and "phy-ctrl" The "phy-ctrl" registers are only required for - "brcm,iproc-ns2-sata-phy". + "brcm,iproc-ns2-sata-phy" and "brcm,iproc-sr-sata-phy". Sub-nodes: Each port's PHY should be represented as a sub-node. @@ -23,8 +24,8 @@ Sub-nodes required properties: Sub-nodes optional properties: - brcm,enable-ssc: use spread spectrum clocking (SSC) on this port - This property is not applicable for "brcm,iproc-ns2-sata-phy" and - "brcm,iproc-nsp-sata-phy". + This property is not applicable for "brcm,iproc-ns2-sata-phy", + "brcm,iproc-nsp-sata-phy" and "brcm,iproc-sr-sata-phy". Example: sata-phy@f0458100 { diff --git a/Documentation/devicetree/bindings/phy/meson-gxl-usb2-phy.txt b/Documentation/devicetree/bindings/phy/meson-gxl-usb2-phy.txt new file mode 100644 index 000000000000..a105494a0fc9 --- /dev/null +++ b/Documentation/devicetree/bindings/phy/meson-gxl-usb2-phy.txt @@ -0,0 +1,17 @@ +* Amlogic Meson GXL and GXM USB2 PHY binding + +Required properties: +- compatible: Should be "amlogic,meson-gxl-usb2-phy" +- reg: The base address and length of the registers +- #phys-cells: must be 0 (see phy-bindings.txt in this directory) + +Optional properties: +- phy-supply: see phy-bindings.txt in this directory + + +Example: + usb2_phy0: phy@78000 { + compatible = "amlogic,meson-gxl-usb2-phy"; + #phy-cells = <0>; + reg = <0x0 0x78000 0x0 0x20>; + }; diff --git a/Documentation/devicetree/bindings/phy/meson8b-usb2-phy.txt b/Documentation/devicetree/bindings/phy/meson8b-usb2-phy.txt index 5fa73b9d20f5..d81d73aea608 100644 --- a/Documentation/devicetree/bindings/phy/meson8b-usb2-phy.txt +++ b/Documentation/devicetree/bindings/phy/meson8b-usb2-phy.txt @@ -1,7 +1,8 @@ -* Amlogic Meson8b and GXBB USB2 PHY +* Amlogic Meson8, Meson8b and GXBB USB2 PHY Required properties: - compatible: Depending on the platform this should be one of: + "amlogic,meson8-usb2-phy" "amlogic,meson8b-usb2-phy" "amlogic,meson-gxbb-usb2-phy" - reg: The base address and length of the registers diff --git a/Documentation/devicetree/bindings/phy/phy-cpcap-usb.txt b/Documentation/devicetree/bindings/phy/phy-cpcap-usb.txt new file mode 100644 index 000000000000..2eb9b2b69037 --- /dev/null +++ b/Documentation/devicetree/bindings/phy/phy-cpcap-usb.txt @@ -0,0 +1,40 @@ +Motorola CPCAP PMIC USB PHY binding + +Required properties: +compatible: Shall be either "motorola,cpcap-usb-phy" or + "motorola,mapphone-cpcap-usb-phy" +#phy-cells: Shall be 0 +interrupts: CPCAP PMIC interrupts used by the USB PHY +interrupt-names: Interrupt names +io-channels: IIO ADC channels used by the USB PHY +io-channel-names: IIO ADC channel names +vusb-supply: Regulator for the PHY + +Optional properties: +pinctrl: Optional alternate pin modes for the PHY +pinctrl-names: Names for optional pin modes +mode-gpios: Optional GPIOs for configuring alternate modes + +Example: +cpcap_usb2_phy: phy { + compatible = "motorola,mapphone-cpcap-usb-phy"; + pinctrl-0 = <&usb_gpio_mux_sel1 &usb_gpio_mux_sel2>; + pinctrl-1 = <&usb_ulpi_pins>; + pinctrl-2 = <&usb_utmi_pins>; + pinctrl-3 = <&uart3_pins>; + pinctrl-names = "default", "ulpi", "utmi", "uart"; + #phy-cells = <0>; + interrupts-extended = < + &cpcap 15 0 &cpcap 14 0 &cpcap 28 0 &cpcap 19 0 + &cpcap 18 0 &cpcap 17 0 &cpcap 16 0 &cpcap 49 0 + &cpcap 48 1 + >; + interrupt-names = + "id_ground", "id_float", "se0conn", "vbusvld", + "sessvld", "sessend", "se1", "dm", "dp"; + mode-gpios = <&gpio2 28 GPIO_ACTIVE_HIGH + &gpio1 0 GPIO_ACTIVE_HIGH>; + io-channels = <&cpcap_adc 2>, <&cpcap_adc 7>; + io-channel-names = "vbus", "id"; + vusb-supply = <&vusb>; +}; diff --git a/Documentation/devicetree/bindings/phy/phy-rockchip-inno-usb2.txt b/Documentation/devicetree/bindings/phy/phy-rockchip-inno-usb2.txt index e71a8d23f4a8..84d59b0db8df 100644 --- a/Documentation/devicetree/bindings/phy/phy-rockchip-inno-usb2.txt +++ b/Documentation/devicetree/bindings/phy/phy-rockchip-inno-usb2.txt @@ -2,6 +2,7 @@ ROCKCHIP USB2.0 PHY WITH INNO IP BLOCK Required properties (phy (parent) node): - compatible : should be one of the listed compatibles: + * "rockchip,rk3228-usb2phy" * "rockchip,rk3328-usb2phy" * "rockchip,rk3366-usb2phy" * "rockchip,rk3399-usb2phy" diff --git a/Documentation/devicetree/bindings/phy/rcar-gen3-phy-usb3.txt b/Documentation/devicetree/bindings/phy/rcar-gen3-phy-usb3.txt new file mode 100644 index 000000000000..f94cea48f6b1 --- /dev/null +++ b/Documentation/devicetree/bindings/phy/rcar-gen3-phy-usb3.txt @@ -0,0 +1,46 @@ +* Renesas R-Car generation 3 USB 3.0 PHY + +This file provides information on what the device node for the R-Car generation +3 USB 3.0 PHY contains. +If you want to enable spread spectrum clock (ssc), you should use USB_EXTAL +instead of USB3_CLK. However, if you don't want to these features, you don't +need this driver. + +Required properties: +- compatible: "renesas,r8a7795-usb3-phy" if the device is a part of an R8A7795 + SoC. + "renesas,r8a7796-usb3-phy" if the device is a part of an R8A7796 + SoC. + "renesas,rcar-gen3-usb3-phy" for a generic R-Car Gen3 compatible + device. + + When compatible with the generic version, nodes must list the + SoC-specific version corresponding to the platform first + followed by the generic version. + +- reg: offset and length of the USB 3.0 PHY register block. +- clocks: A list of phandles and clock-specifier pairs. +- clock-names: Name of the clocks. + - The funcional clock must be "usb3-if". + - The usb3's external clock must be "usb3s_clk". + - The usb2's external clock must be "usb_extal". If you want to use the ssc, + the clock-frequency must not be 0. +- #phy-cells: see phy-bindings.txt in the same directory, must be <0>. + +Optional properties: +- renesas,ssc-range: Enable/disable spread spectrum clock (ssc) by using + the following values as u32: + - 0 (or the property doesn't exist): disable the ssc + - 4980: enable the ssc as -4980 ppm + - 4492: enable the ssc as -4492 ppm + - 4003: enable the ssc as -4003 ppm + +Example (R-Car H3): + + usb-phy@e65ee000 { + compatible = "renesas,r8a7795-usb3-phy", + "renesas,rcar-gen3-usb3-phy"; + reg = <0 0xe65ee000 0 0x90>; + clocks = <&cpg CPG_MOD 328>, <&usb3s0_clk>, <&usb_extal>; + clock-names = "usb3-if", "usb3s_clk", "usb_extal"; + }; diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt b/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt index 71a3c134af1b..f01d154090da 100644 --- a/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt +++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt @@ -247,7 +247,6 @@ bias-bus-hold - latch weakly bias-pull-up - pull up the pin bias-pull-down - pull down the pin bias-pull-pin-default - use pin-default pull state -bi-directional - pin supports simultaneous input/output operations drive-push-pull - drive actively high and low drive-open-drain - drive with open drain drive-open-source - drive with open source @@ -260,7 +259,6 @@ input-debounce - debounce mode with debound time X power-source - select between different power supplies low-power-enable - enable low power mode low-power-disable - disable low power mode -output-enable - enable output on pin regardless of output value output-low - set the pin to output mode with low level output-high - set the pin to output mode with high level slew-rate - set the slew rate diff --git a/Documentation/devicetree/bindings/power/actions,owl-sps.txt b/Documentation/devicetree/bindings/power/actions,owl-sps.txt new file mode 100644 index 000000000000..007b9a7ae723 --- /dev/null +++ b/Documentation/devicetree/bindings/power/actions,owl-sps.txt @@ -0,0 +1,17 @@ +Actions Semi Owl Smart Power System (SPS) + +Required properties: +- compatible : "actions,s500-sps" for S500 +- reg : Offset and length of the register set for the device. +- #power-domain-cells : Must be 1. + See macros in: + include/dt-bindings/power/owl-s500-powergate.h for S500 + + +Example: + + sps: power-controller@b01b0100 { + compatible = "actions,s500-sps"; + reg = <0xb01b0100 0x100>; + #power-domain-cells = <1>; + }; diff --git a/Documentation/devicetree/bindings/power/rockchip-io-domain.txt b/Documentation/devicetree/bindings/power/rockchip-io-domain.txt index d3a5a93a65cd..43c21fb04564 100644 --- a/Documentation/devicetree/bindings/power/rockchip-io-domain.txt +++ b/Documentation/devicetree/bindings/power/rockchip-io-domain.txt @@ -32,6 +32,7 @@ SoC is on the same page. Required properties: - compatible: should be one of: - "rockchip,rk3188-io-voltage-domain" for rk3188 + - "rockchip,rk3228-io-voltage-domain" for rk3228 - "rockchip,rk3288-io-voltage-domain" for rk3288 - "rockchip,rk3328-io-voltage-domain" for rk3328 - "rockchip,rk3368-io-voltage-domain" for rk3368 @@ -59,6 +60,12 @@ Possible supplies for rk3188: - vccio1-supply: The supply connected to VCCIO1. Sometimes also labeled VCCIO1 and VCCIO2. +Possible supplies for rk3228: +- vccio1-supply: The supply connected to VCCIO1. +- vccio2-supply: The supply connected to VCCIO2. +- vccio3-supply: The supply connected to VCCIO3. +- vccio4-supply: The supply connected to VCCIO4. + Possible supplies for rk3288: - audio-supply: The supply connected to APIO4_VDD. - bb-supply: The supply connected to APIO5_VDD. diff --git a/Documentation/devicetree/bindings/power/supply/battery.txt b/Documentation/devicetree/bindings/power/supply/battery.txt new file mode 100644 index 000000000000..f4d3b4a10b43 --- /dev/null +++ b/Documentation/devicetree/bindings/power/supply/battery.txt @@ -0,0 +1,57 @@ +Battery Characteristics + +The devicetree battery node provides static battery characteristics. +In smart batteries, these are typically stored in non-volatile memory +on a fuel gauge chip. The battery node should be used where there is +no appropriate non-volatile memory, or it is unprogrammed/incorrect. + +Upstream dts files should not include battery nodes, unless the battery +represented cannot easily be replaced in the system by one of a +different type. This prevents unpredictable, potentially harmful, +behavior should a replacement that changes the battery type occur +without a corresponding update to the dtb. + +Required Properties: + - compatible: Must be "simple-battery" + +Optional Properties: + - voltage-min-design-microvolt: drained battery voltage + - energy-full-design-microwatt-hours: battery design energy + - charge-full-design-microamp-hours: battery design capacity + - precharge-current-microamp: current for pre-charge phase + - charge-term-current-microamp: current for charge termination phase + - constant-charge-current-max-microamp: maximum constant input current + - constant-charge-voltage-max-microvolt: maximum constant input voltage + +Battery properties are named, where possible, for the corresponding +elements in enum power_supply_property, defined in +https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/power_supply.h + +Batteries must be referenced by chargers and/or fuel-gauges +using a phandle. The phandle's property should be named +"monitored-battery". + +Example: + + bat: battery { + compatible = "simple-battery"; + voltage-min-design-microvolt = <3200000>; + energy-full-design-microwatt-hours = <5290000>; + charge-full-design-microamp-hours = <1430000>; + precharge-current-microamp = <256000>; + charge-term-current-microamp = <128000>; + constant-charge-current-max-microamp = <900000>; + constant-charge-voltage-max-microvolt = <4200000>; + }; + + charger: charger@11 { + .... + monitored-battery = <&bat>; + ... + }; + + fuel_gauge: fuel-gauge@22 { + .... + monitored-battery = <&bat>; + ... + }; diff --git a/Documentation/devicetree/bindings/power/supply/bq27xxx.txt b/Documentation/devicetree/bindings/power/supply/bq27xxx.txt index b0c95ef63e68..6858e1a804ad 100644 --- a/Documentation/devicetree/bindings/power/supply/bq27xxx.txt +++ b/Documentation/devicetree/bindings/power/supply/bq27xxx.txt @@ -1,7 +1,7 @@ -Binding for TI BQ27XXX fuel gauge family +TI BQ27XXX fuel gauge family Required properties: -- compatible: Should contain one of the following: +- compatible: contains one of the following: * "ti,bq27200" - BQ27200 * "ti,bq27210" - BQ27210 * "ti,bq27500" - deprecated, use revision specific property below @@ -26,11 +26,28 @@ Required properties: * "ti,bq27425" - BQ27425 * "ti,bq27441" - BQ27441 * "ti,bq27621" - BQ27621 -- reg: integer, i2c address of the device. +- reg: integer, I2C address of the fuel gauge. + +Optional properties: +- monitored-battery: phandle of battery characteristics node + The fuel gauge uses the following battery properties: + + energy-full-design-microwatt-hours + + charge-full-design-microamp-hours + + voltage-min-design-microvolt + Both or neither of the *-full-design-*-hours properties must be set. + See Documentation/devicetree/bindings/power/supply/battery.txt Example: -bq27510g3 { - compatible = "ti,bq27510g3"; - reg = <0x55>; -}; + bat: battery { + compatible = "simple-battery"; + voltage-min-design-microvolt = <3200000>; + energy-full-design-microwatt-hours = <5290000>; + charge-full-design-microamp-hours = <1430000>; + }; + + bq27510g3: fuel-gauge@55 { + compatible = "ti,bq27510g3"; + reg = <0x55>; + monitored-battery = <&bat>; + }; diff --git a/Documentation/devicetree/bindings/power/supply/cpcap-battery.txt b/Documentation/devicetree/bindings/power/supply/cpcap-battery.txt new file mode 100644 index 000000000000..a04efa22da01 --- /dev/null +++ b/Documentation/devicetree/bindings/power/supply/cpcap-battery.txt @@ -0,0 +1,31 @@ +Motorola CPCAP PMIC battery driver binding + +Required properties: +- compatible: Shall be "motorola,cpcap-battery" +- interrupts: Interrupt specifier for each name in interrupt-names +- interrupt-names: Should contain the following entries: + "lowbph", "lowbpl", "chrgcurr1", "battdetb" +- io-channels: IIO ADC channel specifier for each name in io-channel-names +- io-channel-names: Should contain the following entries: + "battdetb", "battp", "chg_isense", "batti" +- power-supplies: List of phandles for power-supplying devices, as + described in power_supply.txt. Typically a reference + to cpcap_charger. + +Example: + +cpcap_battery: battery { + compatible = "motorola,cpcap-battery"; + interrupts-extended = < + &cpcap 5 0 &cpcap 3 0 + &cpcap 20 0 &cpcap 54 0 + >; + interrupt-names = + "lowbph", "lowbpl", + "chrgcurr1", "battdetb"; + io-channels = <&cpcap_adc 0 &cpcap_adc 1 + &cpcap_adc 5 &cpcap_adc 6>; + io-channel-names = "battdetb", "battp", + "chg_isense", "batti"; + power-supplies = <&cpcap_charger>; +}; diff --git a/Documentation/devicetree/bindings/power/supply/ltc3651-charger.txt b/Documentation/devicetree/bindings/power/supply/ltc3651-charger.txt new file mode 100644 index 000000000000..71f2840e8209 --- /dev/null +++ b/Documentation/devicetree/bindings/power/supply/ltc3651-charger.txt @@ -0,0 +1,27 @@ +ltc3651-charger + +Required properties: + - compatible: "lltc,ltc3651-charger" + - lltc,acpr-gpios: Connect to ACPR output. See remark below. + +Optional properties: + - lltc,fault-gpios: Connect to FAULT output. See remark below. + - lltc,chrg-gpios: Connect to CHRG output. See remark below. + +The ltc3651 outputs are open-drain type and active low. The driver assumes the +GPIO reports "active" when the output is asserted, so if the pins have been +connected directly, the GPIO flags should be set to active low also. + +The driver will attempt to aquire interrupts for all GPIOs to detect changes in +line state. If the system is not capabale of providing interrupts, the driver +cannot report changes and userspace will need to periodically read the sysfs +attributes to detect changes. + +Example: + + charger: battery-charger { + compatible = "lltc,ltc3651-charger"; + lltc,acpr-gpios = <&gpio0 68 GPIO_ACTIVE_LOW>; + lltc,fault-gpios = <&gpio0 64 GPIO_ACTIVE_LOW>; + lltc,chrg-gpios = <&gpio0 63 GPIO_ACTIVE_LOW>; + }; diff --git a/Documentation/devicetree/bindings/power/max8903-charger.txt b/Documentation/devicetree/bindings/power/supply/max8903-charger.txt index f0f4e12b076e..f0f4e12b076e 100644 --- a/Documentation/devicetree/bindings/power/max8903-charger.txt +++ b/Documentation/devicetree/bindings/power/supply/max8903-charger.txt diff --git a/Documentation/devicetree/bindings/power_supply/maxim,max14656.txt b/Documentation/devicetree/bindings/power/supply/maxim,max14656.txt index e03e85ae6572..e03e85ae6572 100644 --- a/Documentation/devicetree/bindings/power_supply/maxim,max14656.txt +++ b/Documentation/devicetree/bindings/power/supply/maxim,max14656.txt diff --git a/Documentation/devicetree/bindings/property-units.txt b/Documentation/devicetree/bindings/property-units.txt index 12278d79f6c0..0849618a9df0 100644 --- a/Documentation/devicetree/bindings/property-units.txt +++ b/Documentation/devicetree/bindings/property-units.txt @@ -25,8 +25,10 @@ Distance Electricity ---------------------------------------- -microamp : micro amps +-microamp-hours : micro amp-hours -ohms : Ohms -micro-ohms : micro Ohms +-microwatt-hours: micro Watt-hours -microvolt : micro volts Temperature diff --git a/Documentation/devicetree/bindings/ptp/brcm,ptp-dte.txt b/Documentation/devicetree/bindings/ptp/brcm,ptp-dte.txt new file mode 100644 index 000000000000..07590bcdad15 --- /dev/null +++ b/Documentation/devicetree/bindings/ptp/brcm,ptp-dte.txt @@ -0,0 +1,13 @@ +* Broadcom Digital Timing Engine(DTE) based PTP clock driver + +Required properties: +- compatible: should be "brcm,ptp-dte" +- reg: address and length of the DTE block's NCO registers + +Example: + +ptp_dte: ptp_dte@180af650 { + compatible = "brcm,ptp-dte"; + reg = <0x180af650 0x10>; + status = "okay"; +}; diff --git a/Documentation/devicetree/bindings/regulator/regulator.txt b/Documentation/devicetree/bindings/regulator/regulator.txt index d18edb075e1c..378f6dc8b8bd 100644 --- a/Documentation/devicetree/bindings/regulator/regulator.txt +++ b/Documentation/devicetree/bindings/regulator/regulator.txt @@ -24,6 +24,14 @@ Optional properties: - regulator-settling-time-us: Settling time, in microseconds, for voltage change if regulator have the constant time for any level voltage change. This is useful when regulator have exponential voltage change. +- regulator-settling-time-up-us: Settling time, in microseconds, for voltage + increase if the regulator needs a constant time to settle after voltage + increases of any level. This is useful for regulators with exponential + voltage changes. +- regulator-settling-time-down-us: Settling time, in microseconds, for voltage + decrease if the regulator needs a constant time to settle after voltage + decreases of any level. This is useful for regulators with exponential + voltage changes. - regulator-soft-start: Enable soft start so that voltage ramps slowly - regulator-state-mem sub-root node for Suspend-to-RAM mode : suspend to memory, the device goes to sleep, but all data stored in memory, diff --git a/Documentation/devicetree/bindings/reset/ti,sci-reset.txt b/Documentation/devicetree/bindings/reset/ti,sci-reset.txt new file mode 100644 index 000000000000..8b1cf022f18a --- /dev/null +++ b/Documentation/devicetree/bindings/reset/ti,sci-reset.txt @@ -0,0 +1,62 @@ +Texas Instruments System Control Interface (TI-SCI) Reset Controller +===================================================================== + +Some TI SoCs contain a system controller (like the Power Management Micro +Controller (PMMC) on Keystone 66AK2G SoC) that are responsible for controlling +the state of the various hardware modules present on the SoC. Communication +between the host processor running an OS and the system controller happens +through a protocol called TI System Control Interface (TI-SCI protocol). +For TI SCI details, please refer to the document, +Documentation/devicetree/bindings/arm/keystone/ti,sci.txt + +TI-SCI Reset Controller Node +============================ +This reset controller node uses the TI SCI protocol to perform the reset +management of various hardware modules present on the SoC. Must be a child +node of the associated TI-SCI system controller node. + +Required properties: +-------------------- + - compatible : Should be "ti,sci-reset" + - #reset-cells : Should be 2. Please see the reset consumer node below for + usage details. + +TI-SCI Reset Consumer Nodes +=========================== +Each of the reset consumer nodes should have the following properties, +in addition to their own properties. + +Required properties: +-------------------- + - resets : A phandle and reset specifier pair, one pair for each reset + signal that affects the device, or that the device manages. + The phandle should point to the TI-SCI reset controller node, + and the reset specifier should have 2 cell-values. The first + cell should contain the device ID. The second cell should + contain the reset mask value used by system controller. + Please refer to the protocol documentation for these values + to be used for different devices, + http://processors.wiki.ti.com/index.php/TISCI#66AK2G02_Data + +Please also refer to Documentation/devicetree/bindings/reset/reset.txt for +common reset controller usage by consumers. + +Example: +-------- +The following example demonstrates both a TI-SCI reset controller node and a +consumer (a DSP device) on the 66AK2G SoC. + +pmmc: pmmc { + compatible = "ti,k2g-sci"; + + k2g_reset: reset-controller { + compatible = "ti,sci-reset"; + #reset-cells = <2>; + }; +}; + +dsp0: dsp@10800000 { + ... + resets = <&k2g_reset 0x0046 0x1>; + ... +}; diff --git a/Documentation/devicetree/bindings/rng/mtk-rng.txt b/Documentation/devicetree/bindings/rng/mtk-rng.txt index a6d62a2abd39..366b99bff8cd 100644 --- a/Documentation/devicetree/bindings/rng/mtk-rng.txt +++ b/Documentation/devicetree/bindings/rng/mtk-rng.txt @@ -2,7 +2,9 @@ Device-Tree bindings for Mediatek random number generator found in Mediatek SoC family Required properties: -- compatible : Should be "mediatek,mt7623-rng" +- compatible : Should be + "mediatek,mt7622-rng", "mediatek,mt7623-rng" : for MT7622 + "mediatek,mt7623-rng" : for MT7623 - clocks : list of clock specifiers, corresponding to entries in clock-names property; - clock-names : Should contain "rng" entries; diff --git a/Documentation/devicetree/bindings/rng/timeriomem_rng.txt b/Documentation/devicetree/bindings/rng/timeriomem_rng.txt index 6616d15866a3..214940093b55 100644 --- a/Documentation/devicetree/bindings/rng/timeriomem_rng.txt +++ b/Documentation/devicetree/bindings/rng/timeriomem_rng.txt @@ -5,6 +5,13 @@ Required properties: - reg : base address to sample from - period : wait time in microseconds to use between samples +Optional properties: +- quality : estimated number of bits of true entropy per 1024 bits read from the + rng. Defaults to zero which causes the kernel's default quality to + be used instead. Note that the default quality is usually zero + which disables using this rng to automatically fill the kernel's + entropy pool. + N.B. currently 'reg' must be four bytes wide and aligned Example: diff --git a/Documentation/devicetree/bindings/serial/8250.txt b/Documentation/devicetree/bindings/serial/8250.txt index 10276a46ecef..419ff6c0a47f 100644 --- a/Documentation/devicetree/bindings/serial/8250.txt +++ b/Documentation/devicetree/bindings/serial/8250.txt @@ -20,6 +20,8 @@ Required properties: - "fsl,16550-FIFO64" - "fsl,ns16550" - "ti,da830-uart" + - "aspeed,ast2400-vuart" + - "aspeed,ast2500-vuart" - "serial" if the port type is unknown. - reg : offset and length of the register set for the device. - interrupts : should contain uart interrupt. @@ -45,6 +47,7 @@ Optional properties: property. - tx-threshold: Specify the TX FIFO low water indication for parts with programmable TX FIFO thresholds. +- resets : phandle + reset specifier pairs Note: * fsl,ns16550: diff --git a/Documentation/devicetree/bindings/serial/actions,owl-uart.txt b/Documentation/devicetree/bindings/serial/actions,owl-uart.txt new file mode 100644 index 000000000000..aa873eada02d --- /dev/null +++ b/Documentation/devicetree/bindings/serial/actions,owl-uart.txt @@ -0,0 +1,16 @@ +Actions Semi Owl UART + +Required properties: +- compatible : "actions,s500-uart", "actions,owl-uart" for S500 + "actions,s900-uart", "actions,owl-uart" for S900 +- reg : Offset and length of the register set for the device. +- interrupts : Should contain UART interrupt. + + +Example: + + uart3: serial@b0126000 { + compatible = "actions,s500-uart", "actions,owl-uart"; + reg = <0xb0126000 0x1000>; + interrupts = <GIC_SPI 32 IRQ_TYPE_LEVEL_HIGH>; + }; diff --git a/Documentation/devicetree/bindings/serial/amlogic,meson-uart.txt b/Documentation/devicetree/bindings/serial/amlogic,meson-uart.txt new file mode 100644 index 000000000000..8ff65fa632fd --- /dev/null +++ b/Documentation/devicetree/bindings/serial/amlogic,meson-uart.txt @@ -0,0 +1,38 @@ +Amlogic Meson SoC UART Serial Interface +======================================= + +The Amlogic Meson SoC UART Serial Interface is present on a large range +of SoCs, and can be present either in the "Always-On" power domain or the +"Everything-Else" power domain. + +The particularity of the "Always-On" Serial Interface is that the hardware +is active since power-on and does not need any clock gating and is usable +as very early serial console. + +Required properties: +- compatible : compatible: value should be different for each SoC family as : + - Meson6 : "amlogic,meson6-uart" + - Meson8 : "amlogic,meson8-uart" + - Meson8b : "amlogic,meson8b-uart" + - GX (GXBB, GXL, GXM) : "amlogic,meson-gx-uart" + eventually followed by : "amlogic,meson-ao-uart" if this UART interface + is in the "Always-On" power domain. +- reg : offset and length of the register set for the device. +- interrupts : identifier to the device interrupt +- clocks : a list of phandle + clock-specifier pairs, one for each + entry in clock names. +- clocks-names : + * "xtal" for external xtal clock identifier + * "pclk" for the bus core clock, either the clk81 clock or the gate clock + * "baud" for the source of the baudrate generator, can be either the xtal + or the pclk. + +e.g. +uart_A: serial@84c0 { + compatible = "amlogic,meson-gx-uart"; + reg = <0x0 0x84c0 0x0 0x14>; + interrupts = <GIC_SPI 26 IRQ_TYPE_EDGE_RISING>; + /* Use xtal as baud rate clock source */ + clocks = <&xtal>, <&clkc CLKID_UART0>, <&xtal>; + clock-names = "xtal", "pclk", "baud"; +}; diff --git a/Documentation/devicetree/bindings/serial/fsl-imx-uart.txt b/Documentation/devicetree/bindings/serial/fsl-imx-uart.txt index 574c3a2c77d5..e6b572409cf5 100644 --- a/Documentation/devicetree/bindings/serial/fsl-imx-uart.txt +++ b/Documentation/devicetree/bindings/serial/fsl-imx-uart.txt @@ -9,6 +9,7 @@ Optional properties: - fsl,irda-mode : Indicate the uart supports irda mode - fsl,dte-mode : Indicate the uart works in DTE mode. The uart works in DCE mode by default. +- fsl,dma-size : Indicate the size of the DMA buffer and its periods Please check Documentation/devicetree/bindings/serial/serial.txt for the complete list of generic properties. @@ -28,4 +29,5 @@ uart1: serial@73fbc000 { interrupts = <31>; uart-has-rtscts; fsl,dte-mode; + fsl,dma-size = <1024 4>; }; diff --git a/Documentation/devicetree/bindings/serial/fsl-lpuart.txt b/Documentation/devicetree/bindings/serial/fsl-lpuart.txt index c95005efbcb8..a1252a047f78 100644 --- a/Documentation/devicetree/bindings/serial/fsl-lpuart.txt +++ b/Documentation/devicetree/bindings/serial/fsl-lpuart.txt @@ -6,6 +6,8 @@ Required properties: on Vybrid vf610 SoC with 8-bit register organization - "fsl,ls1021a-lpuart" for lpuart compatible with the one integrated on LS1021A SoC with 32-bit big-endian register organization + - "fsl,imx7ulp-lpuart" for lpuart compatible with the one integrated + on i.MX7ULP SoC with 32-bit little-endian register organization - reg : Address and length of the register set for the device - interrupts : Should contain uart interrupt - clocks : phandle + clock specifier pairs, one for each entry in clock-names diff --git a/Documentation/devicetree/bindings/serial/mtk-uart.txt b/Documentation/devicetree/bindings/serial/mtk-uart.txt index 0015c722be7b..b6cf384597e1 100644 --- a/Documentation/devicetree/bindings/serial/mtk-uart.txt +++ b/Documentation/devicetree/bindings/serial/mtk-uart.txt @@ -8,6 +8,8 @@ Required properties: * "mediatek,mt6589-uart" for MT6589 compatible UARTS * "mediatek,mt6755-uart" for MT6755 compatible UARTS * "mediatek,mt6795-uart" for MT6795 compatible UARTS + * "mediatek,mt6797-uart" for MT6797 compatible UARTS + * "mediatek,mt7622-uart" for MT7622 compatible UARTS * "mediatek,mt7623-uart" for MT7623 compatible UARTS * "mediatek,mt8127-uart" for MT8127 compatible UARTS * "mediatek,mt8135-uart" for MT8135 compatible UARTS diff --git a/Documentation/devicetree/bindings/serial/slave-device.txt b/Documentation/devicetree/bindings/serial/slave-device.txt index f66037928f5f..40110e019620 100644 --- a/Documentation/devicetree/bindings/serial/slave-device.txt +++ b/Documentation/devicetree/bindings/serial/slave-device.txt @@ -21,6 +21,15 @@ Optional Properties: can support. For example, a particular board has some signal quality issue or the host processor can't support higher baud rates. +- current-speed : The current baud rate the device operates at. This should + only be present in case a driver has no chance to know + the baud rate of the slave device. + Examples: + * device supports auto-baud + * the rate is setup by a bootloader and there is no + way to reset the device + * device baud rate is configured by its firmware but + there is no way to request the actual settings Example: diff --git a/Documentation/devicetree/bindings/soc/mediatek/scpsys.txt b/Documentation/devicetree/bindings/soc/mediatek/scpsys.txt index 16fe94d7783c..b1d165b4d4b3 100644 --- a/Documentation/devicetree/bindings/soc/mediatek/scpsys.txt +++ b/Documentation/devicetree/bindings/soc/mediatek/scpsys.txt @@ -9,11 +9,14 @@ domain control. The driver implements the Generic PM domain bindings described in power/power_domain.txt. It provides the power domains defined in -include/dt-bindings/power/mt8173-power.h and mt2701-power.h. +- include/dt-bindings/power/mt8173-power.h +- include/dt-bindings/power/mt6797-power.h +- include/dt-bindings/power/mt2701-power.h Required properties: - compatible: Should be one of: - "mediatek,mt2701-scpsys" + - "mediatek,mt6797-scpsys" - "mediatek,mt8173-scpsys" - #power-domain-cells: Must be 1 - reg: Address range of the SCPSYS unit @@ -22,6 +25,7 @@ Required properties: These are clocks which hardware needs to be enabled before enabling certain power domains. Required clocks for MT2701: "mm", "mfg", "ethif" + Required clocks for MT6797: "mm", "mfg", "vdec" Required clocks for MT8173: "mm", "mfg", "venc", "venc_lt" Optional properties: diff --git a/Documentation/devicetree/bindings/spi/sh-msiof.txt b/Documentation/devicetree/bindings/spi/sh-msiof.txt index dc975064fa27..64ee489571c4 100644 --- a/Documentation/devicetree/bindings/spi/sh-msiof.txt +++ b/Documentation/devicetree/bindings/spi/sh-msiof.txt @@ -38,6 +38,8 @@ Optional properties: specifiers, one for transmission, and one for reception. - dma-names : Must contain a list of two DMA names, "tx" and "rx". +- spi-slave : Empty property indicating the SPI controller is used + in slave mode. - renesas,dtdl : delay sync signal (setup) in transmit mode. Must contain one of the following values: 0 (no bit delay) diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt index 4b1d6e74c744..1f6e86f787ef 100644 --- a/Documentation/devicetree/bindings/spi/spi-bus.txt +++ b/Documentation/devicetree/bindings/spi/spi-bus.txt @@ -1,17 +1,23 @@ SPI (Serial Peripheral Interface) busses -SPI busses can be described with a node for the SPI master device -and a set of child nodes for each SPI slave on the bus. For this -discussion, it is assumed that the system's SPI controller is in -SPI master mode. This binding does not describe SPI controllers -in slave mode. +SPI busses can be described with a node for the SPI controller device +and a set of child nodes for each SPI slave on the bus. The system's SPI +controller may be described for use in SPI master mode or in SPI slave mode, +but not for both at the same time. -The SPI master node requires the following properties: +The SPI controller node requires the following properties: +- compatible - Name of SPI bus controller following generic names + recommended practice. + +In master mode, the SPI controller node requires the following additional +properties: - #address-cells - number of cells required to define a chip select address on the SPI bus. - #size-cells - should be zero. -- compatible - name of SPI bus controller following generic names - recommended practice. + +In slave mode, the SPI controller node requires one additional property: +- spi-slave - Empty property. + No other properties are required in the SPI bus node. It is assumed that a driver for an SPI bus device will understand that it is an SPI bus. However, the binding does not attempt to define the specific method for @@ -21,7 +27,7 @@ assumption that board specific platform code will be used to manage chip selects. Individual drivers can define additional properties to support describing the chip select layout. -Optional properties: +Optional properties (master mode only): - cs-gpios - gpios chip select. - num-cs - total number of chipselects. @@ -41,28 +47,36 @@ cs1 : native cs2 : &gpio1 1 0 cs3 : &gpio1 2 0 -SPI slave nodes must be children of the SPI master node and can -contain the following properties. -- reg - (required) chip select address of device. -- compatible - (required) name of SPI device following generic names - recommended practice. -- spi-max-frequency - (required) Maximum SPI clocking speed of device in Hz. -- spi-cpol - (optional) Empty property indicating device requires - inverse clock polarity (CPOL) mode. -- spi-cpha - (optional) Empty property indicating device requires - shifted clock phase (CPHA) mode. -- spi-cs-high - (optional) Empty property indicating device requires - chip select active high. -- spi-3wire - (optional) Empty property indicating device requires - 3-wire mode. -- spi-lsb-first - (optional) Empty property indicating device requires - LSB first mode. -- spi-tx-bus-width - (optional) The bus width (number of data wires) that is - used for MOSI. Defaults to 1 if not present. -- spi-rx-bus-width - (optional) The bus width (number of data wires) that is - used for MISO. Defaults to 1 if not present. -- spi-rx-delay-us - (optional) Microsecond delay after a read transfer. -- spi-tx-delay-us - (optional) Microsecond delay after a write transfer. + +SPI slave nodes must be children of the SPI controller node. + +In master mode, one or more slave nodes (up to the number of chip selects) can +be present. Required properties are: +- compatible - Name of SPI device following generic names recommended + practice. +- reg - Chip select address of device. +- spi-max-frequency - Maximum SPI clocking speed of device in Hz. + +In slave mode, the (single) slave node is optional. +If present, it must be called "slave". Required properties are: +- compatible - Name of SPI device following generic names recommended + practice. + +All slave nodes can contain the following optional properties: +- spi-cpol - Empty property indicating device requires inverse clock + polarity (CPOL) mode. +- spi-cpha - Empty property indicating device requires shifted clock + phase (CPHA) mode. +- spi-cs-high - Empty property indicating device requires chip select + active high. +- spi-3wire - Empty property indicating device requires 3-wire mode. +- spi-lsb-first - Empty property indicating device requires LSB first mode. +- spi-tx-bus-width - The bus width (number of data wires) that is used for MOSI. + Defaults to 1 if not present. +- spi-rx-bus-width - The bus width (number of data wires) that is used for MISO. + Defaults to 1 if not present. +- spi-rx-delay-us - Microsecond delay after a read transfer. +- spi-tx-delay-us - Microsecond delay after a write transfer. Some SPI controllers and devices support Dual and Quad SPI transfer mode. It allows data in the SPI system to be transferred using 2 wires (DUAL) or 4 diff --git a/Documentation/devicetree/bindings/spi/spi-meson.txt b/Documentation/devicetree/bindings/spi/spi-meson.txt index dc6d0313324a..825c39cae74a 100644 --- a/Documentation/devicetree/bindings/spi/spi-meson.txt +++ b/Documentation/devicetree/bindings/spi/spi-meson.txt @@ -20,3 +20,34 @@ Required properties: #address-cells = <1>; #size-cells = <0>; }; + +* SPICC (SPI Communication Controller) + +The Meson SPICC is generic SPI controller for general purpose Full-Duplex +communications with dedicated 16 words RX/TX PIO FIFOs. + +Required properties: + - compatible: should be "amlogic,meson-gx-spicc" on Amlogic GX SoCs. + - reg: physical base address and length of the controller registers + - interrupts: The interrupt specifier + - clock-names: Must contain "core" + - clocks: phandle of the input clock for the baud rate generator + - #address-cells: should be 1 + - #size-cells: should be 0 + +Optional properties: + - resets: phandle of the internal reset line + +See ../spi/spi-bus.txt for more details on SPI bus master and slave devices +required and optional properties. + +Example : + spi@c1108d80 { + compatible = "amlogic,meson-gx-spicc"; + reg = <0xc1108d80 0x80>; + interrupts = <GIC_SPI 112 IRQ_TYPE_LEVEL_HIGH>; + clock-names = "core"; + clocks = <&clk81>; + #address-cells = <1>; + #size-cells = <0>; + }; diff --git a/Documentation/devicetree/bindings/spi/spi-mt65xx.txt b/Documentation/devicetree/bindings/spi/spi-mt65xx.txt index e43f4cf4cf35..e0318cf92d73 100644 --- a/Documentation/devicetree/bindings/spi/spi-mt65xx.txt +++ b/Documentation/devicetree/bindings/spi/spi-mt65xx.txt @@ -3,7 +3,9 @@ Binding for MTK SPI controller Required properties: - compatible: should be one of the following. - mediatek,mt2701-spi: for mt2701 platforms + - mediatek,mt2712-spi: for mt2712 platforms - mediatek,mt6589-spi: for mt6589 platforms + - mediatek,mt7622-spi: for mt7622 platforms - mediatek,mt8135-spi: for mt8135 platforms - mediatek,mt8173-spi: for mt8173 platforms diff --git a/Documentation/devicetree/bindings/spi/spi-stm32.txt b/Documentation/devicetree/bindings/spi/spi-stm32.txt new file mode 100644 index 000000000000..1b3fa2c119d5 --- /dev/null +++ b/Documentation/devicetree/bindings/spi/spi-stm32.txt @@ -0,0 +1,59 @@ +STMicroelectronics STM32 SPI Controller + +The STM32 SPI controller is used to communicate with external devices using +the Serial Peripheral Interface. It supports full-duplex, half-duplex and +simplex synchronous serial communication with external devices. It supports +from 4 to 32-bit data size. Although it can be configured as master or slave, +only master is supported by the driver. + +Required properties: +- compatible: Must be "st,stm32h7-spi". +- reg: Offset and length of the device's register set. +- interrupts: Must contain the interrupt id. +- clocks: Must contain an entry for spiclk (which feeds the internal clock + generator). +- #address-cells: Number of cells required to define a chip select address. +- #size-cells: Should be zero. + +Optional properties: +- resets: Must contain the phandle to the reset controller. +- A pinctrl state named "default" may be defined to set pins in mode of + operation for SPI transfer. +- dmas: DMA specifiers for tx and rx dma. DMA fifo mode must be used. See the + STM32 DMA bindings, Documentation/devicetree/bindings/dma/stm32-dma.txt. +- dma-names: DMA request names should include "tx" and "rx" if present. +- cs-gpios: list of GPIO chip selects. See the SPI bus bindings, + Documentation/devicetree/bindings/spi/spi-bus.txt + + +Child nodes represent devices on the SPI bus + See ../spi/spi-bus.txt + +Optional properties: +- st,spi-midi-ns: (Master Inter-Data Idleness) minimum time delay in + nanoseconds inserted between two consecutive data frames. + + +Example: + spi2: spi@40003800 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "st,stm32h7-spi"; + reg = <0x40003800 0x400>; + interrupts = <36>; + clocks = <&rcc SPI2_CK>; + resets = <&rcc 1166>; + dmas = <&dmamux1 0 39 0x400 0x01>, + <&dmamux1 1 40 0x400 0x01>; + dma-names = "rx", "tx"; + pinctrl-0 = <&spi2_pins_b>; + pinctrl-names = "default"; + cs-gpios = <&gpioa 11 0>; + + aardvark@0 { + compatible = "totalphase,aardvark"; + reg = <0>; + spi-max-frequency = <4000000>; + st,spi-midi-ns = <4000>; + }; + }; diff --git a/Documentation/devicetree/bindings/staging/ion/hi6220-ion.txt b/Documentation/devicetree/bindings/staging/ion/hi6220-ion.txt deleted file mode 100644 index c59e27c632c1..000000000000 --- a/Documentation/devicetree/bindings/staging/ion/hi6220-ion.txt +++ /dev/null @@ -1,31 +0,0 @@ -Hi6220 SoC ION -=================================================================== -Required properties: -- compatible : "hisilicon,hi6220-ion" -- list of the ION heaps - - heap name : maybe heap_sys_user@0 - - heap id : id should be unique in the system. - - heap base : base ddr address of the heap,0 means that - it is dynamic. - - heap size : memory size and 0 means it is dynamic. - - heap type : the heap type of the heap, please also - see the define in ion.h(drivers/staging/android/uapi/ion.h) -------------------------------------------------------------------- -Example: - hi6220-ion { - compatible = "hisilicon,hi6220-ion"; - heap_sys_user@0 { - heap-name = "sys_user"; - heap-id = <0x0>; - heap-base = <0x0>; - heap-size = <0x0>; - heap-type = "ion_system"; - }; - heap_sys_contig@0 { - heap-name = "sys_contig"; - heap-id = <0x1>; - heap-base = <0x0>; - heap-size = <0x0>; - heap-type = "ion_system_contig"; - }; - }; diff --git a/Documentation/devicetree/bindings/timer/actions,owl-timer.txt b/Documentation/devicetree/bindings/timer/actions,owl-timer.txt new file mode 100644 index 000000000000..e3c28da80cb2 --- /dev/null +++ b/Documentation/devicetree/bindings/timer/actions,owl-timer.txt @@ -0,0 +1,20 @@ +Actions Semi Owl Timer + +Required properties: +- compatible : "actions,s500-timer" for S500 + "actions,s900-timer" for S900 +- reg : Offset and length of the register set for the device. +- interrupts : Should contain the interrupts. +- interrupt-names : Valid names are: "2hz0", "2hz1", + "timer0", "timer1", "timer2", "timer3" + See ../resource-names.txt + +Example: + + timer@b0168000 { + compatible = "actions,s500-timer"; + reg = <0xb0168000 0x100>; + interrupts = <GIC_SPI 10 IRQ_TYPE_LEVEL_HIGH>, + <GIC_SPI 11 IRQ_TYPE_LEVEL_HIGH>; + interrupt-names = "timer0", "timer1"; + }; diff --git a/Documentation/devicetree/bindings/timer/faraday,fttmr010.txt b/Documentation/devicetree/bindings/timer/faraday,fttmr010.txt index b73ca6cd07f8..195792270414 100644 --- a/Documentation/devicetree/bindings/timer/faraday,fttmr010.txt +++ b/Documentation/devicetree/bindings/timer/faraday,fttmr010.txt @@ -7,7 +7,11 @@ Required properties: - compatible : Must be one of "faraday,fttmr010" - "cortina,gemini-timer" + "cortina,gemini-timer", "faraday,fttmr010" + "moxa,moxart-timer", "faraday,fttmr010" + "aspeed,ast2400-timer" + "aspeed,ast2500-timer" + - reg : Should contain registers location and length - interrupts : Should contain the three timer interrupts usually with flags for falling edge diff --git a/Documentation/devicetree/bindings/timer/moxa,moxart-timer.txt b/Documentation/devicetree/bindings/timer/moxa,moxart-timer.txt deleted file mode 100644 index e207c11630af..000000000000 --- a/Documentation/devicetree/bindings/timer/moxa,moxart-timer.txt +++ /dev/null @@ -1,19 +0,0 @@ -MOXA ART timer - -Required properties: - -- compatible : Must be one of: - - "moxa,moxart-timer" - - "aspeed,ast2400-timer" -- reg : Should contain registers location and length -- interrupts : Should contain the timer interrupt number -- clocks : Should contain phandle for the clock that drives the counter - -Example: - - timer: timer@98400000 { - compatible = "moxa,moxart-timer"; - reg = <0x98400000 0x42>; - interrupts = <19 1>; - clocks = <&coreclk>; - }; diff --git a/Documentation/devicetree/bindings/trivial-devices.txt b/Documentation/devicetree/bindings/trivial-devices.txt index 3e0a34c88e07..35f406dd86b6 100644 --- a/Documentation/devicetree/bindings/trivial-devices.txt +++ b/Documentation/devicetree/bindings/trivial-devices.txt @@ -55,6 +55,7 @@ gmt,g751 G751: Digital Temperature Sensor and Thermal Watchdog with Two-Wire In infineon,slb9635tt Infineon SLB9635 (Soft-) I2C TPM (old protocol, max 100khz) infineon,slb9645tt Infineon SLB9645 I2C TPM (new protocol, max 400khz) isil,isl29028 Intersil ISL29028 Ambient Light and Proximity Sensor +isil,isl29030 Intersil ISL29030 Ambient Light and Proximity Sensor maxim,ds1050 5 Bit Programmable, Pulse-Width Modulator maxim,max1237 Low-Power, 4-/12-Channel, 2-Wire Serial, 12-Bit ADCs maxim,max6625 9-Bit/12-Bit Temperature Sensors with I²C-Compatible Serial Interface diff --git a/Documentation/devicetree/bindings/usb/dwc2.txt b/Documentation/devicetree/bindings/usb/dwc2.txt index 00bea038639e..fcf199b64d3d 100644 --- a/Documentation/devicetree/bindings/usb/dwc2.txt +++ b/Documentation/devicetree/bindings/usb/dwc2.txt @@ -10,6 +10,7 @@ Required properties: - "rockchip,rk3288-usb", "rockchip,rk3066-usb", "snps,dwc2": for rk3288 Soc; - "lantiq,arx100-usb": The DWC2 USB controller instance in Lantiq ARX SoCs; - "lantiq,xrx200-usb": The DWC2 USB controller instance in Lantiq XRX SoCs; + - "amlogic,meson8-usb": The DWC2 USB controller instance in Amlogic Meson8 SoCs; - "amlogic,meson8b-usb": The DWC2 USB controller instance in Amlogic Meson8b SoCs; - "amlogic,meson-gxbb-usb": The DWC2 USB controller instance in Amlogic S905 SoCs; - "amcc,dwc-otg": The DWC2 USB controller instance in AMCC Canyonlands 460EX SoCs; diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt index f658f394c2d3..52fb41046b34 100644 --- a/Documentation/devicetree/bindings/usb/dwc3.txt +++ b/Documentation/devicetree/bindings/usb/dwc3.txt @@ -45,6 +45,8 @@ Optional properties: a free-running PHY clock. - snps,dis-del-phy-power-chg-quirk: when set core will change PHY power from P0 to P1/P2/P3 without delay. + - snps,dis-tx-ipgap-linecheck-quirk: when set, disable u2mac linestate check + during HS transmit. - snps,is-utmi-l1-suspend: true when DWC3 asserts output signal utmi_l1_suspend_n, false when asserts utmi_sleep_n - snps,hird-threshold: HIRD threshold diff --git a/Documentation/devicetree/bindings/usb/iproc-udc.txt b/Documentation/devicetree/bindings/usb/iproc-udc.txt new file mode 100644 index 000000000000..272d7faf1a97 --- /dev/null +++ b/Documentation/devicetree/bindings/usb/iproc-udc.txt @@ -0,0 +1,21 @@ +Broadcom IPROC USB Device controller. + +The device node is used for UDCs integrated into Broadcom's +iProc family (Northstar2, Cygnus) of SoCs'. The UDC is based +on Synopsys Designware Cores AHB Subsystem Device Controller +IP. + +Required properties: + - compatible: Add the compatibility strings for supported platforms. + For Broadcom NS2 platform, add "brcm,ns2-udc","brcm,iproc-udc". + For Broadcom Cygnus platform, add "brcm,cygnus-udc", "brcm,iproc-udc". + - reg: Offset and length of UDC register set + - interrupts: description of interrupt line + - phys: phandle to phy node. + +Example: + udc_dwc: usb@664e0000 { + compatible = "brcm,ns2-udc", "brcm,iproc-udc"; + reg = <0x664e0000 0x2000>; + interrupts = <GIC_SPI 424 IRQ_TYPE_LEVEL_HIGH>; + phys = <&usbdrd_phy>; diff --git a/Documentation/devicetree/bindings/usb/usb-ohci.txt b/Documentation/devicetree/bindings/usb/usb-ohci.txt index 9df456968596..e8766b08c93b 100644 --- a/Documentation/devicetree/bindings/usb/usb-ohci.txt +++ b/Documentation/devicetree/bindings/usb/usb-ohci.txt @@ -10,6 +10,7 @@ Optional properties: - big-endian-desc : boolean, set this for hcds with big-endian descriptors - big-endian : boolean, for hcds with big-endian-regs + big-endian-desc - no-big-frame-no : boolean, set if frame_no lives in bits [15:0] of HCCA +- remote-wakeup-connected: remote wakeup is wired on the platform - num-ports : u32, to override the detected port count - clocks : a list of phandle + clock specifier pairs - phys : phandle + phy specifier pair diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt index c03d20140366..286f4e1e111f 100644 --- a/Documentation/devicetree/bindings/vendor-prefixes.txt +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt @@ -5,6 +5,7 @@ using them to avoid name-space collisions. abcn Abracon Corporation abilis Abilis Systems +actions Actions Semiconductor Co., Ltd. active-semi Active-Semi International Inc ad Avionic Design GmbH adapteva Adapteva, Inc. @@ -165,6 +166,7 @@ keithkoep Keith & Koep GmbH keymile Keymile GmbH khadas Khadas kinetic Kinetic Technologies +kingnovel Kingnovel Technology Co., Ltd. kosagi Sutajio Ko-Usagi PTE Ltd. kyo Kyocera Corporation lacie LaCie @@ -172,6 +174,7 @@ lantiq Lantiq Semiconductor lego LEGO Systems A/S lenovo Lenovo Group Ltd. lg LG Corporation +libretech Shenzhen Libre Technology Co., Ltd licheepi Lichee Pi linaro Linaro Limited linux Linux-specific binding @@ -331,6 +334,7 @@ tronfy Tronfy tronsmart Tronsmart truly Truly Semiconductors Limited tyan Tyan Computer Corporation +ucrobotics uCRobotics udoo Udoo uniwest United Western Technologies Corp (UniWest) upisemi uPI Semiconductor Corp. @@ -356,6 +360,7 @@ xlnx Xilinx xunlong Shenzhen Xunlong Software CO.,Limited zarlink Zarlink Semiconductor zeitec ZEITEC Semiconductor Co., LTD. +zidoo Shenzhen Zidoo Technology Co., Ltd. zii Zodiac Inflight Innovations zte ZTE Corp. zyxel ZyXEL Communications Corp. diff --git a/Documentation/doc-guide/docbook.rst b/Documentation/doc-guide/docbook.rst deleted file mode 100644 index d8bf04308b43..000000000000 --- a/Documentation/doc-guide/docbook.rst +++ /dev/null @@ -1,90 +0,0 @@ -DocBook XML [DEPRECATED] -======================== - -.. attention:: - - This section describes the deprecated DocBook XML toolchain. Please do not - create new DocBook XML template files. Please consider converting existing - DocBook XML templates files to Sphinx/reStructuredText. - -Converting DocBook to Sphinx ----------------------------- - -Over time, we expect all of the documents under ``Documentation/DocBook`` to be -converted to Sphinx and reStructuredText. For most DocBook XML documents, a good -enough solution is to use the simple ``Documentation/sphinx/tmplcvt`` script, -which uses ``pandoc`` under the hood. For example:: - - $ cd Documentation/sphinx - $ ./tmplcvt ../DocBook/in.tmpl ../out.rst - -Then edit the resulting rst files to fix any remaining issues, and add the -document in the ``toctree`` in ``Documentation/index.rst``. - -Components of the kernel-doc system ------------------------------------ - -Many places in the source tree have extractable documentation in the form of -block comments above functions. The components of this system are: - -- ``scripts/kernel-doc`` - - This is a perl script that hunts for the block comments and can mark them up - directly into reStructuredText, DocBook, man, text, and HTML. (No, not - texinfo.) - -- ``Documentation/DocBook/*.tmpl`` - - These are XML template files, which are normal XML files with special - place-holders for where the extracted documentation should go. - -- ``scripts/docproc.c`` - - This is a program for converting XML template files into XML files. When a - file is referenced it is searched for symbols exported (EXPORT_SYMBOL), to be - able to distinguish between internal and external functions. - - It invokes kernel-doc, giving it the list of functions that are to be - documented. - - Additionally it is used to scan the XML template files to locate all the files - referenced herein. This is used to generate dependency information as used by - make. - -- ``Makefile`` - - The targets 'xmldocs', 'psdocs', 'pdfdocs', and 'htmldocs' are used to build - DocBook XML files, PostScript files, PDF files, and html files in - Documentation/DocBook. The older target 'sgmldocs' is equivalent to 'xmldocs'. - -- ``Documentation/DocBook/Makefile`` - - This is where C files are associated with SGML templates. - -How to use kernel-doc comments in DocBook XML template files ------------------------------------------------------------- - -DocBook XML template files (\*.tmpl) are like normal XML files, except that they -can contain escape sequences where extracted documentation should be inserted. - -``!E<filename>`` is replaced by the documentation, in ``<filename>``, for -functions that are exported using ``EXPORT_SYMBOL``: the function list is -collected from files listed in ``Documentation/DocBook/Makefile``. - -``!I<filename>`` is replaced by the documentation for functions that are **not** -exported using ``EXPORT_SYMBOL``. - -``!D<filename>`` is used to name additional files to search for functions -exported using ``EXPORT_SYMBOL``. - -``!F<filename> <function [functions...]>`` is replaced by the documentation, in -``<filename>``, for the functions listed. - -``!P<filename> <section title>`` is replaced by the contents of the ``DOC:`` -section titled ``<section title>`` from ``<filename>``. Spaces are allowed in -``<section title>``; do not quote the ``<section title>``. - -``!C<filename>`` is replaced by nothing, but makes the tools check that all DOC: -sections and documented functions, symbols, etc. are used. This makes sense to -use when you use ``!F`` or ``!P`` only and want to verify that all documentation -is included. diff --git a/Documentation/doc-guide/index.rst b/Documentation/doc-guide/index.rst index 6fff4024606e..a7f95d7d3a63 100644 --- a/Documentation/doc-guide/index.rst +++ b/Documentation/doc-guide/index.rst @@ -10,7 +10,6 @@ How to write kernel documentation sphinx.rst kernel-doc.rst parse-headers.rst - docbook.rst .. only:: subproject and html diff --git a/Documentation/doc-guide/kernel-doc.rst b/Documentation/doc-guide/kernel-doc.rst index b32e4813ff6f..b24854b5d6be 100644 --- a/Documentation/doc-guide/kernel-doc.rst +++ b/Documentation/doc-guide/kernel-doc.rst @@ -149,6 +149,16 @@ Domain`_ references. ``%CONST`` Name of a constant. (No cross-referencing, just formatting.) +````literal```` + A literal block that should be handled as-is. The output will use a + ``monospaced font``. + + Useful if you need to use special characters that would otherwise have some + meaning either by kernel-doc script of by reStructuredText. + + This is particularly useful if you need to use things like ``%ph`` inside + a function description. + ``$ENVVAR`` Name of an environment variable. (No cross-referencing, just formatting.) diff --git a/Documentation/doc-guide/sphinx.rst b/Documentation/doc-guide/sphinx.rst index 731334de3efd..84e8e8a9cbdb 100644 --- a/Documentation/doc-guide/sphinx.rst +++ b/Documentation/doc-guide/sphinx.rst @@ -15,11 +15,6 @@ are used to describe the functions and types and design of the code. The kernel-doc comments have some special structure and formatting, but beyond that they are also treated as reStructuredText. -There is also the deprecated DocBook toolchain to generate documentation from -DocBook XML template files under ``Documentation/DocBook``. The DocBook files -are to be converted to reStructuredText, and the toolchain is slated to be -removed. - Finally, there are thousands of plain text documentation files scattered around ``Documentation``. Some of these will likely be converted to reStructuredText over time, but the bulk of them will remain in plain text. diff --git a/Documentation/dontdiff b/Documentation/dontdiff index 77b92221f951..358b47c06ad4 100644 --- a/Documentation/dontdiff +++ b/Documentation/dontdiff @@ -118,7 +118,6 @@ defkeymap.c devlist.h* devicetable-offsets.h dnotify_test -docproc dslm dtc elf2ecoff @@ -207,6 +206,8 @@ r200_reg_safe.h r300_reg_safe.h r420_reg_safe.h r600_reg_safe.h +randomize_layout_hash.h +randomize_layout_seed.h recordmcount relocs rlim_names.h diff --git a/Documentation/driver-api/firmware/request_firmware.rst b/Documentation/driver-api/firmware/request_firmware.rst index cc0aea880824..1c2c4967cd43 100644 --- a/Documentation/driver-api/firmware/request_firmware.rst +++ b/Documentation/driver-api/firmware/request_firmware.rst @@ -44,6 +44,17 @@ request_firmware_nowait .. kernel-doc:: drivers/base/firmware_class.c :functions: request_firmware_nowait +Considerations for suspend and resume +===================================== + +During suspend and resume only the built-in firmware and the firmware cache +elements of the firmware API can be used. This is managed by fw_pm_notify(). + +fw_pm_notify +------------ +.. kernel-doc:: drivers/base/firmware_class.c + :functions: fw_pm_notify + request firmware API expected driver use ======================================== diff --git a/Documentation/driver-api/i2c.rst b/Documentation/driver-api/i2c.rst index f3939f7852bd..0bf86a445d01 100644 --- a/Documentation/driver-api/i2c.rst +++ b/Documentation/driver-api/i2c.rst @@ -13,8 +13,8 @@ I2C is a multi-master bus; open drain signaling is used to arbitrate between masters, as well as to handshake and to synchronize clocks from slower clients. -The Linux I2C programming interfaces support only the master side of bus -interactions, not the slave side. The programming interface is +The Linux I2C programming interfaces support the master side of bus +interactions and the slave side. The programming interface is structured around two kinds of driver, and two kinds of device. An I2C "Adapter Driver" abstracts the controller hardware; it binds to a physical device (perhaps a PCI device or platform_device) and exposes a @@ -22,9 +22,8 @@ physical device (perhaps a PCI device or platform_device) and exposes a I2C bus segment it manages. On each I2C bus segment will be I2C devices represented by a :c:type:`struct i2c_client <i2c_client>`. Those devices will be bound to a :c:type:`struct i2c_driver -<i2c_driver>`, which should follow the standard Linux driver -model. (At this writing, a legacy model is more widely used.) There are -functions to perform various I2C protocol operations; at this writing +<i2c_driver>`, which should follow the standard Linux driver model. There +are functions to perform various I2C protocol operations; at this writing all such functions are usable only from task context. The System Management Bus (SMBus) is a sibling protocol. Most SMBus diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst index 8058a87c1c74..3cf1acebc4ee 100644 --- a/Documentation/driver-api/index.rst +++ b/Documentation/driver-api/index.rst @@ -32,7 +32,13 @@ available subsections can be seen below. i2c hsi edac + scsi + libata + mtdnand miscellaneous + w1 + rapidio + s390-drivers vme 80211/index uio-howto diff --git a/Documentation/driver-api/libata.rst b/Documentation/driver-api/libata.rst new file mode 100644 index 000000000000..4adc056f7635 --- /dev/null +++ b/Documentation/driver-api/libata.rst @@ -0,0 +1,1031 @@ +======================== +libATA Developer's Guide +======================== + +:Author: Jeff Garzik + +Introduction +============ + +libATA is a library used inside the Linux kernel to support ATA host +controllers and devices. libATA provides an ATA driver API, class +transports for ATA and ATAPI devices, and SCSI<->ATA translation for ATA +devices according to the T10 SAT specification. + +This Guide documents the libATA driver API, library functions, library +internals, and a couple sample ATA low-level drivers. + +libata Driver API +================= + +:c:type:`struct ata_port_operations <ata_port_operations>` +is defined for every low-level libata +hardware driver, and it controls how the low-level driver interfaces +with the ATA and SCSI layers. + +FIS-based drivers will hook into the system with ``->qc_prep()`` and +``->qc_issue()`` high-level hooks. Hardware which behaves in a manner +similar to PCI IDE hardware may utilize several generic helpers, +defining at a bare minimum the bus I/O addresses of the ATA shadow +register blocks. + +:c:type:`struct ata_port_operations <ata_port_operations>` +---------------------------------------------------------- + +Disable ATA port +~~~~~~~~~~~~~~~~ + +:: + + void (*port_disable) (struct ata_port *); + + +Called from :c:func:`ata_bus_probe` error path, as well as when unregistering +from the SCSI module (rmmod, hot unplug). This function should do +whatever needs to be done to take the port out of use. In most cases, +:c:func:`ata_port_disable` can be used as this hook. + +Called from :c:func:`ata_bus_probe` on a failed probe. Called from +:c:func:`ata_scsi_release`. + +Post-IDENTIFY device configuration +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + void (*dev_config) (struct ata_port *, struct ata_device *); + + +Called after IDENTIFY [PACKET] DEVICE is issued to each device found. +Typically used to apply device-specific fixups prior to issue of SET +FEATURES - XFER MODE, and prior to operation. + +This entry may be specified as NULL in ata_port_operations. + +Set PIO/DMA mode +~~~~~~~~~~~~~~~~ + +:: + + void (*set_piomode) (struct ata_port *, struct ata_device *); + void (*set_dmamode) (struct ata_port *, struct ata_device *); + void (*post_set_mode) (struct ata_port *); + unsigned int (*mode_filter) (struct ata_port *, struct ata_device *, unsigned int); + + +Hooks called prior to the issue of SET FEATURES - XFER MODE command. The +optional ``->mode_filter()`` hook is called when libata has built a mask of +the possible modes. This is passed to the ``->mode_filter()`` function +which should return a mask of valid modes after filtering those +unsuitable due to hardware limits. It is not valid to use this interface +to add modes. + +``dev->pio_mode`` and ``dev->dma_mode`` are guaranteed to be valid when +``->set_piomode()`` and when ``->set_dmamode()`` is called. The timings for +any other drive sharing the cable will also be valid at this point. That +is the library records the decisions for the modes of each drive on a +channel before it attempts to set any of them. + +``->post_set_mode()`` is called unconditionally, after the SET FEATURES - +XFER MODE command completes successfully. + +``->set_piomode()`` is always called (if present), but ``->set_dma_mode()`` +is only called if DMA is possible. + +Taskfile read/write +~~~~~~~~~~~~~~~~~~~ + +:: + + void (*sff_tf_load) (struct ata_port *ap, struct ata_taskfile *tf); + void (*sff_tf_read) (struct ata_port *ap, struct ata_taskfile *tf); + + +``->tf_load()`` is called to load the given taskfile into hardware +registers / DMA buffers. ``->tf_read()`` is called to read the hardware +registers / DMA buffers, to obtain the current set of taskfile register +values. Most drivers for taskfile-based hardware (PIO or MMIO) use +:c:func:`ata_sff_tf_load` and :c:func:`ata_sff_tf_read` for these hooks. + +PIO data read/write +~~~~~~~~~~~~~~~~~~~ + +:: + + void (*sff_data_xfer) (struct ata_device *, unsigned char *, unsigned int, int); + + +All bmdma-style drivers must implement this hook. This is the low-level +operation that actually copies the data bytes during a PIO data +transfer. Typically the driver will choose one of +:c:func:`ata_sff_data_xfer_noirq`, :c:func:`ata_sff_data_xfer`, or +:c:func:`ata_sff_data_xfer32`. + +ATA command execute +~~~~~~~~~~~~~~~~~~~ + +:: + + void (*sff_exec_command)(struct ata_port *ap, struct ata_taskfile *tf); + + +causes an ATA command, previously loaded with ``->tf_load()``, to be +initiated in hardware. Most drivers for taskfile-based hardware use +:c:func:`ata_sff_exec_command` for this hook. + +Per-cmd ATAPI DMA capabilities filter +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + int (*check_atapi_dma) (struct ata_queued_cmd *qc); + + +Allow low-level driver to filter ATA PACKET commands, returning a status +indicating whether or not it is OK to use DMA for the supplied PACKET +command. + +This hook may be specified as NULL, in which case libata will assume +that atapi dma can be supported. + +Read specific ATA shadow registers +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + u8 (*sff_check_status)(struct ata_port *ap); + u8 (*sff_check_altstatus)(struct ata_port *ap); + + +Reads the Status/AltStatus ATA shadow register from hardware. On some +hardware, reading the Status register has the side effect of clearing +the interrupt condition. Most drivers for taskfile-based hardware use +:c:func:`ata_sff_check_status` for this hook. + +Write specific ATA shadow register +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + void (*sff_set_devctl)(struct ata_port *ap, u8 ctl); + + +Write the device control ATA shadow register to the hardware. Most +drivers don't need to define this. + +Select ATA device on bus +~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + void (*sff_dev_select)(struct ata_port *ap, unsigned int device); + + +Issues the low-level hardware command(s) that causes one of N hardware +devices to be considered 'selected' (active and available for use) on +the ATA bus. This generally has no meaning on FIS-based devices. + +Most drivers for taskfile-based hardware use :c:func:`ata_sff_dev_select` for +this hook. + +Private tuning method +~~~~~~~~~~~~~~~~~~~~~ + +:: + + void (*set_mode) (struct ata_port *ap); + + +By default libata performs drive and controller tuning in accordance +with the ATA timing rules and also applies blacklists and cable limits. +Some controllers need special handling and have custom tuning rules, +typically raid controllers that use ATA commands but do not actually do +drive timing. + + **Warning** + + This hook should not be used to replace the standard controller + tuning logic when a controller has quirks. Replacing the default + tuning logic in that case would bypass handling for drive and bridge + quirks that may be important to data reliability. If a controller + needs to filter the mode selection it should use the mode_filter + hook instead. + +Control PCI IDE BMDMA engine +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + void (*bmdma_setup) (struct ata_queued_cmd *qc); + void (*bmdma_start) (struct ata_queued_cmd *qc); + void (*bmdma_stop) (struct ata_port *ap); + u8 (*bmdma_status) (struct ata_port *ap); + + +When setting up an IDE BMDMA transaction, these hooks arm +(``->bmdma_setup``), fire (``->bmdma_start``), and halt (``->bmdma_stop``) the +hardware's DMA engine. ``->bmdma_status`` is used to read the standard PCI +IDE DMA Status register. + +These hooks are typically either no-ops, or simply not implemented, in +FIS-based drivers. + +Most legacy IDE drivers use :c:func:`ata_bmdma_setup` for the +:c:func:`bmdma_setup` hook. :c:func:`ata_bmdma_setup` will write the pointer +to the PRD table to the IDE PRD Table Address register, enable DMA in the DMA +Command register, and call :c:func:`exec_command` to begin the transfer. + +Most legacy IDE drivers use :c:func:`ata_bmdma_start` for the +:c:func:`bmdma_start` hook. :c:func:`ata_bmdma_start` will write the +ATA_DMA_START flag to the DMA Command register. + +Many legacy IDE drivers use :c:func:`ata_bmdma_stop` for the +:c:func:`bmdma_stop` hook. :c:func:`ata_bmdma_stop` clears the ATA_DMA_START +flag in the DMA command register. + +Many legacy IDE drivers use :c:func:`ata_bmdma_status` as the +:c:func:`bmdma_status` hook. + +High-level taskfile hooks +~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + void (*qc_prep) (struct ata_queued_cmd *qc); + int (*qc_issue) (struct ata_queued_cmd *qc); + + +Higher-level hooks, these two hooks can potentially supercede several of +the above taskfile/DMA engine hooks. ``->qc_prep`` is called after the +buffers have been DMA-mapped, and is typically used to populate the +hardware's DMA scatter-gather table. Most drivers use the standard +:c:func:`ata_qc_prep` helper function, but more advanced drivers roll their +own. + +``->qc_issue`` is used to make a command active, once the hardware and S/G +tables have been prepared. IDE BMDMA drivers use the helper function +:c:func:`ata_qc_issue_prot` for taskfile protocol-based dispatch. More +advanced drivers implement their own ``->qc_issue``. + +:c:func:`ata_qc_issue_prot` calls ``->tf_load()``, ``->bmdma_setup()``, and +``->bmdma_start()`` as necessary to initiate a transfer. + +Exception and probe handling (EH) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + void (*eng_timeout) (struct ata_port *ap); + void (*phy_reset) (struct ata_port *ap); + + +Deprecated. Use ``->error_handler()`` instead. + +:: + + void (*freeze) (struct ata_port *ap); + void (*thaw) (struct ata_port *ap); + + +:c:func:`ata_port_freeze` is called when HSM violations or some other +condition disrupts normal operation of the port. A frozen port is not +allowed to perform any operation until the port is thawed, which usually +follows a successful reset. + +The optional ``->freeze()`` callback can be used for freezing the port +hardware-wise (e.g. mask interrupt and stop DMA engine). If a port +cannot be frozen hardware-wise, the interrupt handler must ack and clear +interrupts unconditionally while the port is frozen. + +The optional ``->thaw()`` callback is called to perform the opposite of +``->freeze()``: prepare the port for normal operation once again. Unmask +interrupts, start DMA engine, etc. + +:: + + void (*error_handler) (struct ata_port *ap); + + +``->error_handler()`` is a driver's hook into probe, hotplug, and recovery +and other exceptional conditions. The primary responsibility of an +implementation is to call :c:func:`ata_do_eh` or :c:func:`ata_bmdma_drive_eh` +with a set of EH hooks as arguments: + +'prereset' hook (may be NULL) is called during an EH reset, before any +other actions are taken. + +'postreset' hook (may be NULL) is called after the EH reset is +performed. Based on existing conditions, severity of the problem, and +hardware capabilities, + +Either 'softreset' (may be NULL) or 'hardreset' (may be NULL) will be +called to perform the low-level EH reset. + +:: + + void (*post_internal_cmd) (struct ata_queued_cmd *qc); + + +Perform any hardware-specific actions necessary to finish processing +after executing a probe-time or EH-time command via +:c:func:`ata_exec_internal`. + +Hardware interrupt handling +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + irqreturn_t (*irq_handler)(int, void *, struct pt_regs *); + void (*irq_clear) (struct ata_port *); + + +``->irq_handler`` is the interrupt handling routine registered with the +system, by libata. ``->irq_clear`` is called during probe just before the +interrupt handler is registered, to be sure hardware is quiet. + +The second argument, dev_instance, should be cast to a pointer to +:c:type:`struct ata_host_set <ata_host_set>`. + +Most legacy IDE drivers use :c:func:`ata_sff_interrupt` for the irq_handler +hook, which scans all ports in the host_set, determines which queued +command was active (if any), and calls ata_sff_host_intr(ap,qc). + +Most legacy IDE drivers use :c:func:`ata_sff_irq_clear` for the +:c:func:`irq_clear` hook, which simply clears the interrupt and error flags +in the DMA status register. + +SATA phy read/write +~~~~~~~~~~~~~~~~~~~ + +:: + + int (*scr_read) (struct ata_port *ap, unsigned int sc_reg, + u32 *val); + int (*scr_write) (struct ata_port *ap, unsigned int sc_reg, + u32 val); + + +Read and write standard SATA phy registers. Currently only used if +``->phy_reset`` hook called the :c:func:`sata_phy_reset` helper function. +sc_reg is one of SCR_STATUS, SCR_CONTROL, SCR_ERROR, or SCR_ACTIVE. + +Init and shutdown +~~~~~~~~~~~~~~~~~ + +:: + + int (*port_start) (struct ata_port *ap); + void (*port_stop) (struct ata_port *ap); + void (*host_stop) (struct ata_host_set *host_set); + + +``->port_start()`` is called just after the data structures for each port +are initialized. Typically this is used to alloc per-port DMA buffers / +tables / rings, enable DMA engines, and similar tasks. Some drivers also +use this entry point as a chance to allocate driver-private memory for +``ap->private_data``. + +Many drivers use :c:func:`ata_port_start` as this hook or call it from their +own :c:func:`port_start` hooks. :c:func:`ata_port_start` allocates space for +a legacy IDE PRD table and returns. + +``->port_stop()`` is called after ``->host_stop()``. Its sole function is to +release DMA/memory resources, now that they are no longer actively being +used. Many drivers also free driver-private data from port at this time. + +``->host_stop()`` is called after all ``->port_stop()`` calls have completed. +The hook must finalize hardware shutdown, release DMA and other +resources, etc. This hook may be specified as NULL, in which case it is +not called. + +Error handling +============== + +This chapter describes how errors are handled under libata. Readers are +advised to read SCSI EH (Documentation/scsi/scsi_eh.txt) and ATA +exceptions doc first. + +Origins of commands +------------------- + +In libata, a command is represented with +:c:type:`struct ata_queued_cmd <ata_queued_cmd>` or qc. +qc's are preallocated during port initialization and repetitively used +for command executions. Currently only one qc is allocated per port but +yet-to-be-merged NCQ branch allocates one for each tag and maps each qc +to NCQ tag 1-to-1. + +libata commands can originate from two sources - libata itself and SCSI +midlayer. libata internal commands are used for initialization and error +handling. All normal blk requests and commands for SCSI emulation are +passed as SCSI commands through queuecommand callback of SCSI host +template. + +How commands are issued +----------------------- + +Internal commands + First, qc is allocated and initialized using :c:func:`ata_qc_new_init`. + Although :c:func:`ata_qc_new_init` doesn't implement any wait or retry + mechanism when qc is not available, internal commands are currently + issued only during initialization and error recovery, so no other + command is active and allocation is guaranteed to succeed. + + Once allocated qc's taskfile is initialized for the command to be + executed. qc currently has two mechanisms to notify completion. One + is via ``qc->complete_fn()`` callback and the other is completion + ``qc->waiting``. ``qc->complete_fn()`` callback is the asynchronous path + used by normal SCSI translated commands and ``qc->waiting`` is the + synchronous (issuer sleeps in process context) path used by internal + commands. + + Once initialization is complete, host_set lock is acquired and the + qc is issued. + +SCSI commands + All libata drivers use :c:func:`ata_scsi_queuecmd` as + ``hostt->queuecommand`` callback. scmds can either be simulated or + translated. No qc is involved in processing a simulated scmd. The + result is computed right away and the scmd is completed. + + For a translated scmd, :c:func:`ata_qc_new_init` is invoked to allocate a + qc and the scmd is translated into the qc. SCSI midlayer's + completion notification function pointer is stored into + ``qc->scsidone``. + + ``qc->complete_fn()`` callback is used for completion notification. ATA + commands use :c:func:`ata_scsi_qc_complete` while ATAPI commands use + :c:func:`atapi_qc_complete`. Both functions end up calling ``qc->scsidone`` + to notify upper layer when the qc is finished. After translation is + completed, the qc is issued with :c:func:`ata_qc_issue`. + + Note that SCSI midlayer invokes hostt->queuecommand while holding + host_set lock, so all above occur while holding host_set lock. + +How commands are processed +-------------------------- + +Depending on which protocol and which controller are used, commands are +processed differently. For the purpose of discussion, a controller which +uses taskfile interface and all standard callbacks is assumed. + +Currently 6 ATA command protocols are used. They can be sorted into the +following four categories according to how they are processed. + +ATA NO DATA or DMA + ATA_PROT_NODATA and ATA_PROT_DMA fall into this category. These + types of commands don't require any software intervention once + issued. Device will raise interrupt on completion. + +ATA PIO + ATA_PROT_PIO is in this category. libata currently implements PIO + with polling. ATA_NIEN bit is set to turn off interrupt and + pio_task on ata_wq performs polling and IO. + +ATAPI NODATA or DMA + ATA_PROT_ATAPI_NODATA and ATA_PROT_ATAPI_DMA are in this + category. packet_task is used to poll BSY bit after issuing PACKET + command. Once BSY is turned off by the device, packet_task + transfers CDB and hands off processing to interrupt handler. + +ATAPI PIO + ATA_PROT_ATAPI is in this category. ATA_NIEN bit is set and, as + in ATAPI NODATA or DMA, packet_task submits cdb. However, after + submitting cdb, further processing (data transfer) is handed off to + pio_task. + +How commands are completed +-------------------------- + +Once issued, all qc's are either completed with :c:func:`ata_qc_complete` or +time out. For commands which are handled by interrupts, +:c:func:`ata_host_intr` invokes :c:func:`ata_qc_complete`, and, for PIO tasks, +pio_task invokes :c:func:`ata_qc_complete`. In error cases, packet_task may +also complete commands. + +:c:func:`ata_qc_complete` does the following. + +1. DMA memory is unmapped. + +2. ATA_QCFLAG_ACTIVE is cleared from qc->flags. + +3. :c:func:`qc->complete_fn` callback is invoked. If the return value of the + callback is not zero. Completion is short circuited and + :c:func:`ata_qc_complete` returns. + +4. :c:func:`__ata_qc_complete` is called, which does + + 1. ``qc->flags`` is cleared to zero. + + 2. ``ap->active_tag`` and ``qc->tag`` are poisoned. + + 3. ``qc->waiting`` is cleared & completed (in that order). + + 4. qc is deallocated by clearing appropriate bit in ``ap->qactive``. + +So, it basically notifies upper layer and deallocates qc. One exception +is short-circuit path in #3 which is used by :c:func:`atapi_qc_complete`. + +For all non-ATAPI commands, whether it fails or not, almost the same +code path is taken and very little error handling takes place. A qc is +completed with success status if it succeeded, with failed status +otherwise. + +However, failed ATAPI commands require more handling as REQUEST SENSE is +needed to acquire sense data. If an ATAPI command fails, +:c:func:`ata_qc_complete` is invoked with error status, which in turn invokes +:c:func:`atapi_qc_complete` via ``qc->complete_fn()`` callback. + +This makes :c:func:`atapi_qc_complete` set ``scmd->result`` to +SAM_STAT_CHECK_CONDITION, complete the scmd and return 1. As the +sense data is empty but ``scmd->result`` is CHECK CONDITION, SCSI midlayer +will invoke EH for the scmd, and returning 1 makes :c:func:`ata_qc_complete` +to return without deallocating the qc. This leads us to +:c:func:`ata_scsi_error` with partially completed qc. + +:c:func:`ata_scsi_error` +------------------------ + +:c:func:`ata_scsi_error` is the current ``transportt->eh_strategy_handler()`` +for libata. As discussed above, this will be entered in two cases - +timeout and ATAPI error completion. This function calls low level libata +driver's :c:func:`eng_timeout` callback, the standard callback for which is +:c:func:`ata_eng_timeout`. It checks if a qc is active and calls +:c:func:`ata_qc_timeout` on the qc if so. Actual error handling occurs in +:c:func:`ata_qc_timeout`. + +If EH is invoked for timeout, :c:func:`ata_qc_timeout` stops BMDMA and +completes the qc. Note that as we're currently in EH, we cannot call +scsi_done. As described in SCSI EH doc, a recovered scmd should be +either retried with :c:func:`scsi_queue_insert` or finished with +:c:func:`scsi_finish_command`. Here, we override ``qc->scsidone`` with +:c:func:`scsi_finish_command` and calls :c:func:`ata_qc_complete`. + +If EH is invoked due to a failed ATAPI qc, the qc here is completed but +not deallocated. The purpose of this half-completion is to use the qc as +place holder to make EH code reach this place. This is a bit hackish, +but it works. + +Once control reaches here, the qc is deallocated by invoking +:c:func:`__ata_qc_complete` explicitly. Then, internal qc for REQUEST SENSE +is issued. Once sense data is acquired, scmd is finished by directly +invoking :c:func:`scsi_finish_command` on the scmd. Note that as we already +have completed and deallocated the qc which was associated with the +scmd, we don't need to/cannot call :c:func:`ata_qc_complete` again. + +Problems with the current EH +---------------------------- + +- Error representation is too crude. Currently any and all error + conditions are represented with ATA STATUS and ERROR registers. + Errors which aren't ATA device errors are treated as ATA device + errors by setting ATA_ERR bit. Better error descriptor which can + properly represent ATA and other errors/exceptions is needed. + +- When handling timeouts, no action is taken to make device forget + about the timed out command and ready for new commands. + +- EH handling via :c:func:`ata_scsi_error` is not properly protected from + usual command processing. On EH entrance, the device is not in + quiescent state. Timed out commands may succeed or fail any time. + pio_task and atapi_task may still be running. + +- Too weak error recovery. Devices / controllers causing HSM mismatch + errors and other errors quite often require reset to return to known + state. Also, advanced error handling is necessary to support features + like NCQ and hotplug. + +- ATA errors are directly handled in the interrupt handler and PIO + errors in pio_task. This is problematic for advanced error handling + for the following reasons. + + First, advanced error handling often requires context and internal qc + execution. + + Second, even a simple failure (say, CRC error) needs information + gathering and could trigger complex error handling (say, resetting & + reconfiguring). Having multiple code paths to gather information, + enter EH and trigger actions makes life painful. + + Third, scattered EH code makes implementing low level drivers + difficult. Low level drivers override libata callbacks. If EH is + scattered over several places, each affected callbacks should perform + its part of error handling. This can be error prone and painful. + +libata Library +============== + +.. kernel-doc:: drivers/ata/libata-core.c + :export: + +libata Core Internals +===================== + +.. kernel-doc:: drivers/ata/libata-core.c + :internal: + +.. kernel-doc:: drivers/ata/libata-eh.c + +libata SCSI translation/emulation +================================= + +.. kernel-doc:: drivers/ata/libata-scsi.c + :export: + +.. kernel-doc:: drivers/ata/libata-scsi.c + :internal: + +ATA errors and exceptions +========================= + +This chapter tries to identify what error/exception conditions exist for +ATA/ATAPI devices and describe how they should be handled in +implementation-neutral way. + +The term 'error' is used to describe conditions where either an explicit +error condition is reported from device or a command has timed out. + +The term 'exception' is either used to describe exceptional conditions +which are not errors (say, power or hotplug events), or to describe both +errors and non-error exceptional conditions. Where explicit distinction +between error and exception is necessary, the term 'non-error exception' +is used. + +Exception categories +-------------------- + +Exceptions are described primarily with respect to legacy taskfile + bus +master IDE interface. If a controller provides other better mechanism +for error reporting, mapping those into categories described below +shouldn't be difficult. + +In the following sections, two recovery actions - reset and +reconfiguring transport - are mentioned. These are described further in +`EH recovery actions <#exrec>`__. + +HSM violation +~~~~~~~~~~~~~ + +This error is indicated when STATUS value doesn't match HSM requirement +during issuing or execution any ATA/ATAPI command. + +- ATA_STATUS doesn't contain !BSY && DRDY && !DRQ while trying to + issue a command. + +- !BSY && !DRQ during PIO data transfer. + +- DRQ on command completion. + +- !BSY && ERR after CDB transfer starts but before the last byte of CDB + is transferred. ATA/ATAPI standard states that "The device shall not + terminate the PACKET command with an error before the last byte of + the command packet has been written" in the error outputs description + of PACKET command and the state diagram doesn't include such + transitions. + +In these cases, HSM is violated and not much information regarding the +error can be acquired from STATUS or ERROR register. IOW, this error can +be anything - driver bug, faulty device, controller and/or cable. + +As HSM is violated, reset is necessary to restore known state. +Reconfiguring transport for lower speed might be helpful too as +transmission errors sometimes cause this kind of errors. + +ATA/ATAPI device error (non-NCQ / non-CHECK CONDITION) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +These are errors detected and reported by ATA/ATAPI devices indicating +device problems. For this type of errors, STATUS and ERROR register +values are valid and describe error condition. Note that some of ATA bus +errors are detected by ATA/ATAPI devices and reported using the same +mechanism as device errors. Those cases are described later in this +section. + +For ATA commands, this type of errors are indicated by !BSY && ERR +during command execution and on completion. + +For ATAPI commands, + +- !BSY && ERR && ABRT right after issuing PACKET indicates that PACKET + command is not supported and falls in this category. + +- !BSY && ERR(==CHK) && !ABRT after the last byte of CDB is transferred + indicates CHECK CONDITION and doesn't fall in this category. + +- !BSY && ERR(==CHK) && ABRT after the last byte of CDB is transferred + \*probably\* indicates CHECK CONDITION and doesn't fall in this + category. + +Of errors detected as above, the following are not ATA/ATAPI device +errors but ATA bus errors and should be handled according to +`ATA bus error <#excatATAbusErr>`__. + +CRC error during data transfer + This is indicated by ICRC bit in the ERROR register and means that + corruption occurred during data transfer. Up to ATA/ATAPI-7, the + standard specifies that this bit is only applicable to UDMA + transfers but ATA/ATAPI-8 draft revision 1f says that the bit may be + applicable to multiword DMA and PIO. + +ABRT error during data transfer or on completion + Up to ATA/ATAPI-7, the standard specifies that ABRT could be set on + ICRC errors and on cases where a device is not able to complete a + command. Combined with the fact that MWDMA and PIO transfer errors + aren't allowed to use ICRC bit up to ATA/ATAPI-7, it seems to imply + that ABRT bit alone could indicate transfer errors. + + However, ATA/ATAPI-8 draft revision 1f removes the part that ICRC + errors can turn on ABRT. So, this is kind of gray area. Some + heuristics are needed here. + +ATA/ATAPI device errors can be further categorized as follows. + +Media errors + This is indicated by UNC bit in the ERROR register. ATA devices + reports UNC error only after certain number of retries cannot + recover the data, so there's nothing much else to do other than + notifying upper layer. + + READ and WRITE commands report CHS or LBA of the first failed sector + but ATA/ATAPI standard specifies that the amount of transferred data + on error completion is indeterminate, so we cannot assume that + sectors preceding the failed sector have been transferred and thus + cannot complete those sectors successfully as SCSI does. + +Media changed / media change requested error + <<TODO: fill here>> + +Address error + This is indicated by IDNF bit in the ERROR register. Report to upper + layer. + +Other errors + This can be invalid command or parameter indicated by ABRT ERROR bit + or some other error condition. Note that ABRT bit can indicate a lot + of things including ICRC and Address errors. Heuristics needed. + +Depending on commands, not all STATUS/ERROR bits are applicable. These +non-applicable bits are marked with "na" in the output descriptions but +up to ATA/ATAPI-7 no definition of "na" can be found. However, +ATA/ATAPI-8 draft revision 1f describes "N/A" as follows. + + 3.2.3.3a N/A + A keyword the indicates a field has no defined value in this + standard and should not be checked by the host or device. N/A + fields should be cleared to zero. + +So, it seems reasonable to assume that "na" bits are cleared to zero by +devices and thus need no explicit masking. + +ATAPI device CHECK CONDITION +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +ATAPI device CHECK CONDITION error is indicated by set CHK bit (ERR bit) +in the STATUS register after the last byte of CDB is transferred for a +PACKET command. For this kind of errors, sense data should be acquired +to gather information regarding the errors. REQUEST SENSE packet command +should be used to acquire sense data. + +Once sense data is acquired, this type of errors can be handled +similarly to other SCSI errors. Note that sense data may indicate ATA +bus error (e.g. Sense Key 04h HARDWARE ERROR && ASC/ASCQ 47h/00h SCSI +PARITY ERROR). In such cases, the error should be considered as an ATA +bus error and handled according to `ATA bus error <#excatATAbusErr>`__. + +ATA device error (NCQ) +~~~~~~~~~~~~~~~~~~~~~~ + +NCQ command error is indicated by cleared BSY and set ERR bit during NCQ +command phase (one or more NCQ commands outstanding). Although STATUS +and ERROR registers will contain valid values describing the error, READ +LOG EXT is required to clear the error condition, determine which +command has failed and acquire more information. + +READ LOG EXT Log Page 10h reports which tag has failed and taskfile +register values describing the error. With this information the failed +command can be handled as a normal ATA command error as in +`ATA/ATAPI device error (non-NCQ / non-CHECK CONDITION) <#excatDevErr>`__ +and all other in-flight commands must be retried. Note that this retry +should not be counted - it's likely that commands retried this way would +have completed normally if it were not for the failed command. + +Note that ATA bus errors can be reported as ATA device NCQ errors. This +should be handled as described in `ATA bus error <#excatATAbusErr>`__. + +If READ LOG EXT Log Page 10h fails or reports NQ, we're thoroughly +screwed. This condition should be treated according to +`HSM violation <#excatHSMviolation>`__. + +ATA bus error +~~~~~~~~~~~~~ + +ATA bus error means that data corruption occurred during transmission +over ATA bus (SATA or PATA). This type of errors can be indicated by + +- ICRC or ABRT error as described in + `ATA/ATAPI device error (non-NCQ / non-CHECK CONDITION) <#excatDevErr>`__. + +- Controller-specific error completion with error information + indicating transmission error. + +- On some controllers, command timeout. In this case, there may be a + mechanism to determine that the timeout is due to transmission error. + +- Unknown/random errors, timeouts and all sorts of weirdities. + +As described above, transmission errors can cause wide variety of +symptoms ranging from device ICRC error to random device lockup, and, +for many cases, there is no way to tell if an error condition is due to +transmission error or not; therefore, it's necessary to employ some kind +of heuristic when dealing with errors and timeouts. For example, +encountering repetitive ABRT errors for known supported command is +likely to indicate ATA bus error. + +Once it's determined that ATA bus errors have possibly occurred, +lowering ATA bus transmission speed is one of actions which may +alleviate the problem. See `Reconfigure transport <#exrecReconf>`__ for +more information. + +PCI bus error +~~~~~~~~~~~~~ + +Data corruption or other failures during transmission over PCI (or other +system bus). For standard BMDMA, this is indicated by Error bit in the +BMDMA Status register. This type of errors must be logged as it +indicates something is very wrong with the system. Resetting host +controller is recommended. + +Late completion +~~~~~~~~~~~~~~~ + +This occurs when timeout occurs and the timeout handler finds out that +the timed out command has completed successfully or with error. This is +usually caused by lost interrupts. This type of errors must be logged. +Resetting host controller is recommended. + +Unknown error (timeout) +~~~~~~~~~~~~~~~~~~~~~~~ + +This is when timeout occurs and the command is still processing or the +host and device are in unknown state. When this occurs, HSM could be in +any valid or invalid state. To bring the device to known state and make +it forget about the timed out command, resetting is necessary. The timed +out command may be retried. + +Timeouts can also be caused by transmission errors. Refer to +`ATA bus error <#excatATAbusErr>`__ for more details. + +Hotplug and power management exceptions +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +<<TODO: fill here>> + +EH recovery actions +------------------- + +This section discusses several important recovery actions. + +Clearing error condition +~~~~~~~~~~~~~~~~~~~~~~~~ + +Many controllers require its error registers to be cleared by error +handler. Different controllers may have different requirements. + +For SATA, it's strongly recommended to clear at least SError register +during error handling. + +Reset +~~~~~ + +During EH, resetting is necessary in the following cases. + +- HSM is in unknown or invalid state + +- HBA is in unknown or invalid state + +- EH needs to make HBA/device forget about in-flight commands + +- HBA/device behaves weirdly + +Resetting during EH might be a good idea regardless of error condition +to improve EH robustness. Whether to reset both or either one of HBA and +device depends on situation but the following scheme is recommended. + +- When it's known that HBA is in ready state but ATA/ATAPI device is in + unknown state, reset only device. + +- If HBA is in unknown state, reset both HBA and device. + +HBA resetting is implementation specific. For a controller complying to +taskfile/BMDMA PCI IDE, stopping active DMA transaction may be +sufficient iff BMDMA state is the only HBA context. But even mostly +taskfile/BMDMA PCI IDE complying controllers may have implementation +specific requirements and mechanism to reset themselves. This must be +addressed by specific drivers. + +OTOH, ATA/ATAPI standard describes in detail ways to reset ATA/ATAPI +devices. + +PATA hardware reset + This is hardware initiated device reset signalled with asserted PATA + RESET- signal. There is no standard way to initiate hardware reset + from software although some hardware provides registers that allow + driver to directly tweak the RESET- signal. + +Software reset + This is achieved by turning CONTROL SRST bit on for at least 5us. + Both PATA and SATA support it but, in case of SATA, this may require + controller-specific support as the second Register FIS to clear SRST + should be transmitted while BSY bit is still set. Note that on PATA, + this resets both master and slave devices on a channel. + +EXECUTE DEVICE DIAGNOSTIC command + Although ATA/ATAPI standard doesn't describe exactly, EDD implies + some level of resetting, possibly similar level with software reset. + Host-side EDD protocol can be handled with normal command processing + and most SATA controllers should be able to handle EDD's just like + other commands. As in software reset, EDD affects both devices on a + PATA bus. + + Although EDD does reset devices, this doesn't suit error handling as + EDD cannot be issued while BSY is set and it's unclear how it will + act when device is in unknown/weird state. + +ATAPI DEVICE RESET command + This is very similar to software reset except that reset can be + restricted to the selected device without affecting the other device + sharing the cable. + +SATA phy reset + This is the preferred way of resetting a SATA device. In effect, + it's identical to PATA hardware reset. Note that this can be done + with the standard SCR Control register. As such, it's usually easier + to implement than software reset. + +One more thing to consider when resetting devices is that resetting +clears certain configuration parameters and they need to be set to their +previous or newly adjusted values after reset. + +Parameters affected are. + +- CHS set up with INITIALIZE DEVICE PARAMETERS (seldom used) + +- Parameters set with SET FEATURES including transfer mode setting + +- Block count set with SET MULTIPLE MODE + +- Other parameters (SET MAX, MEDIA LOCK...) + +ATA/ATAPI standard specifies that some parameters must be maintained +across hardware or software reset, but doesn't strictly specify all of +them. Always reconfiguring needed parameters after reset is required for +robustness. Note that this also applies when resuming from deep sleep +(power-off). + +Also, ATA/ATAPI standard requires that IDENTIFY DEVICE / IDENTIFY PACKET +DEVICE is issued after any configuration parameter is updated or a +hardware reset and the result used for further operation. OS driver is +required to implement revalidation mechanism to support this. + +Reconfigure transport +~~~~~~~~~~~~~~~~~~~~~ + +For both PATA and SATA, a lot of corners are cut for cheap connectors, +cables or controllers and it's quite common to see high transmission +error rate. This can be mitigated by lowering transmission speed. + +The following is a possible scheme Jeff Garzik suggested. + + If more than $N (3?) transmission errors happen in 15 minutes, + + - if SATA, decrease SATA PHY speed. if speed cannot be decreased, + + - decrease UDMA xfer speed. if at UDMA0, switch to PIO4, + + - decrease PIO xfer speed. if at PIO3, complain, but continue + +ata_piix Internals +=================== + +.. kernel-doc:: drivers/ata/ata_piix.c + :internal: + +sata_sil Internals +=================== + +.. kernel-doc:: drivers/ata/sata_sil.c + :internal: + +Thanks +====== + +The bulk of the ATA knowledge comes thanks to long conversations with +Andre Hedrick (www.linux-ide.org), and long hours pondering the ATA and +SCSI specifications. + +Thanks to Alan Cox for pointing out similarities between SATA and SCSI, +and in general for motivation to hack on libata. + +libata's device detection method, ata_pio_devchk, and in general all +the early probing was based on extensive study of Hale Landis's +probe/reset code in his ATADRVR driver (www.ata-atapi.com). diff --git a/Documentation/driver-api/mtdnand.rst b/Documentation/driver-api/mtdnand.rst new file mode 100644 index 000000000000..e9afa586d15e --- /dev/null +++ b/Documentation/driver-api/mtdnand.rst @@ -0,0 +1,1007 @@ +===================================== +MTD NAND Driver Programming Interface +===================================== + +:Author: Thomas Gleixner + +Introduction +============ + +The generic NAND driver supports almost all NAND and AG-AND based chips +and connects them to the Memory Technology Devices (MTD) subsystem of +the Linux Kernel. + +This documentation is provided for developers who want to implement +board drivers or filesystem drivers suitable for NAND devices. + +Known Bugs And Assumptions +========================== + +None. + +Documentation hints +=================== + +The function and structure docs are autogenerated. Each function and +struct member has a short description which is marked with an [XXX] +identifier. The following chapters explain the meaning of those +identifiers. + +Function identifiers [XXX] +-------------------------- + +The functions are marked with [XXX] identifiers in the short comment. +The identifiers explain the usage and scope of the functions. Following +identifiers are used: + +- [MTD Interface] + + These functions provide the interface to the MTD kernel API. They are + not replaceable and provide functionality which is complete hardware + independent. + +- [NAND Interface] + + These functions are exported and provide the interface to the NAND + kernel API. + +- [GENERIC] + + Generic functions are not replaceable and provide functionality which + is complete hardware independent. + +- [DEFAULT] + + Default functions provide hardware related functionality which is + suitable for most of the implementations. These functions can be + replaced by the board driver if necessary. Those functions are called + via pointers in the NAND chip description structure. The board driver + can set the functions which should be replaced by board dependent + functions before calling nand_scan(). If the function pointer is + NULL on entry to nand_scan() then the pointer is set to the default + function which is suitable for the detected chip type. + +Struct member identifiers [XXX] +------------------------------- + +The struct members are marked with [XXX] identifiers in the comment. The +identifiers explain the usage and scope of the members. Following +identifiers are used: + +- [INTERN] + + These members are for NAND driver internal use only and must not be + modified. Most of these values are calculated from the chip geometry + information which is evaluated during nand_scan(). + +- [REPLACEABLE] + + Replaceable members hold hardware related functions which can be + provided by the board driver. The board driver can set the functions + which should be replaced by board dependent functions before calling + nand_scan(). If the function pointer is NULL on entry to + nand_scan() then the pointer is set to the default function which is + suitable for the detected chip type. + +- [BOARDSPECIFIC] + + Board specific members hold hardware related information which must + be provided by the board driver. The board driver must set the + function pointers and datafields before calling nand_scan(). + +- [OPTIONAL] + + Optional members can hold information relevant for the board driver. + The generic NAND driver code does not use this information. + +Basic board driver +================== + +For most boards it will be sufficient to provide just the basic +functions and fill out some really board dependent members in the nand +chip description structure. + +Basic defines +------------- + +At least you have to provide a nand_chip structure and a storage for +the ioremap'ed chip address. You can allocate the nand_chip structure +using kmalloc or you can allocate it statically. The NAND chip structure +embeds an mtd structure which will be registered to the MTD subsystem. +You can extract a pointer to the mtd structure from a nand_chip pointer +using the nand_to_mtd() helper. + +Kmalloc based example + +:: + + static struct mtd_info *board_mtd; + static void __iomem *baseaddr; + + +Static example + +:: + + static struct nand_chip board_chip; + static void __iomem *baseaddr; + + +Partition defines +----------------- + +If you want to divide your device into partitions, then define a +partitioning scheme suitable to your board. + +:: + + #define NUM_PARTITIONS 2 + static struct mtd_partition partition_info[] = { + { .name = "Flash partition 1", + .offset = 0, + .size = 8 * 1024 * 1024 }, + { .name = "Flash partition 2", + .offset = MTDPART_OFS_NEXT, + .size = MTDPART_SIZ_FULL }, + }; + + +Hardware control function +------------------------- + +The hardware control function provides access to the control pins of the +NAND chip(s). The access can be done by GPIO pins or by address lines. +If you use address lines, make sure that the timing requirements are +met. + +*GPIO based example* + +:: + + static void board_hwcontrol(struct mtd_info *mtd, int cmd) + { + switch(cmd){ + case NAND_CTL_SETCLE: /* Set CLE pin high */ break; + case NAND_CTL_CLRCLE: /* Set CLE pin low */ break; + case NAND_CTL_SETALE: /* Set ALE pin high */ break; + case NAND_CTL_CLRALE: /* Set ALE pin low */ break; + case NAND_CTL_SETNCE: /* Set nCE pin low */ break; + case NAND_CTL_CLRNCE: /* Set nCE pin high */ break; + } + } + + +*Address lines based example.* It's assumed that the nCE pin is driven +by a chip select decoder. + +:: + + static void board_hwcontrol(struct mtd_info *mtd, int cmd) + { + struct nand_chip *this = mtd_to_nand(mtd); + switch(cmd){ + case NAND_CTL_SETCLE: this->IO_ADDR_W |= CLE_ADRR_BIT; break; + case NAND_CTL_CLRCLE: this->IO_ADDR_W &= ~CLE_ADRR_BIT; break; + case NAND_CTL_SETALE: this->IO_ADDR_W |= ALE_ADRR_BIT; break; + case NAND_CTL_CLRALE: this->IO_ADDR_W &= ~ALE_ADRR_BIT; break; + } + } + + +Device ready function +--------------------- + +If the hardware interface has the ready busy pin of the NAND chip +connected to a GPIO or other accessible I/O pin, this function is used +to read back the state of the pin. The function has no arguments and +should return 0, if the device is busy (R/B pin is low) and 1, if the +device is ready (R/B pin is high). If the hardware interface does not +give access to the ready busy pin, then the function must not be defined +and the function pointer this->dev_ready is set to NULL. + +Init function +------------- + +The init function allocates memory and sets up all the board specific +parameters and function pointers. When everything is set up nand_scan() +is called. This function tries to detect and identify then chip. If a +chip is found all the internal data fields are initialized accordingly. +The structure(s) have to be zeroed out first and then filled with the +necessary information about the device. + +:: + + static int __init board_init (void) + { + struct nand_chip *this; + int err = 0; + + /* Allocate memory for MTD device structure and private data */ + this = kzalloc(sizeof(struct nand_chip), GFP_KERNEL); + if (!this) { + printk ("Unable to allocate NAND MTD device structure.\n"); + err = -ENOMEM; + goto out; + } + + board_mtd = nand_to_mtd(this); + + /* map physical address */ + baseaddr = ioremap(CHIP_PHYSICAL_ADDRESS, 1024); + if (!baseaddr) { + printk("Ioremap to access NAND chip failed\n"); + err = -EIO; + goto out_mtd; + } + + /* Set address of NAND IO lines */ + this->IO_ADDR_R = baseaddr; + this->IO_ADDR_W = baseaddr; + /* Reference hardware control function */ + this->hwcontrol = board_hwcontrol; + /* Set command delay time, see datasheet for correct value */ + this->chip_delay = CHIP_DEPENDEND_COMMAND_DELAY; + /* Assign the device ready function, if available */ + this->dev_ready = board_dev_ready; + this->eccmode = NAND_ECC_SOFT; + + /* Scan to find existence of the device */ + if (nand_scan (board_mtd, 1)) { + err = -ENXIO; + goto out_ior; + } + + add_mtd_partitions(board_mtd, partition_info, NUM_PARTITIONS); + goto out; + + out_ior: + iounmap(baseaddr); + out_mtd: + kfree (this); + out: + return err; + } + module_init(board_init); + + +Exit function +------------- + +The exit function is only necessary if the driver is compiled as a +module. It releases all resources which are held by the chip driver and +unregisters the partitions in the MTD layer. + +:: + + #ifdef MODULE + static void __exit board_cleanup (void) + { + /* Release resources, unregister device */ + nand_release (board_mtd); + + /* unmap physical address */ + iounmap(baseaddr); + + /* Free the MTD device structure */ + kfree (mtd_to_nand(board_mtd)); + } + module_exit(board_cleanup); + #endif + + +Advanced board driver functions +=============================== + +This chapter describes the advanced functionality of the NAND driver. +For a list of functions which can be overridden by the board driver see +the documentation of the nand_chip structure. + +Multiple chip control +--------------------- + +The nand driver can control chip arrays. Therefore the board driver must +provide an own select_chip function. This function must (de)select the +requested chip. The function pointer in the nand_chip structure must be +set before calling nand_scan(). The maxchip parameter of nand_scan() +defines the maximum number of chips to scan for. Make sure that the +select_chip function can handle the requested number of chips. + +The nand driver concatenates the chips to one virtual chip and provides +this virtual chip to the MTD layer. + +*Note: The driver can only handle linear chip arrays of equally sized +chips. There is no support for parallel arrays which extend the +buswidth.* + +*GPIO based example* + +:: + + static void board_select_chip (struct mtd_info *mtd, int chip) + { + /* Deselect all chips, set all nCE pins high */ + GPIO(BOARD_NAND_NCE) |= 0xff; + if (chip >= 0) + GPIO(BOARD_NAND_NCE) &= ~ (1 << chip); + } + + +*Address lines based example.* Its assumed that the nCE pins are +connected to an address decoder. + +:: + + static void board_select_chip (struct mtd_info *mtd, int chip) + { + struct nand_chip *this = mtd_to_nand(mtd); + + /* Deselect all chips */ + this->IO_ADDR_R &= ~BOARD_NAND_ADDR_MASK; + this->IO_ADDR_W &= ~BOARD_NAND_ADDR_MASK; + switch (chip) { + case 0: + this->IO_ADDR_R |= BOARD_NAND_ADDR_CHIP0; + this->IO_ADDR_W |= BOARD_NAND_ADDR_CHIP0; + break; + .... + case n: + this->IO_ADDR_R |= BOARD_NAND_ADDR_CHIPn; + this->IO_ADDR_W |= BOARD_NAND_ADDR_CHIPn; + break; + } + } + + +Hardware ECC support +-------------------- + +Functions and constants +~~~~~~~~~~~~~~~~~~~~~~~ + +The nand driver supports three different types of hardware ECC. + +- NAND_ECC_HW3_256 + + Hardware ECC generator providing 3 bytes ECC per 256 byte. + +- NAND_ECC_HW3_512 + + Hardware ECC generator providing 3 bytes ECC per 512 byte. + +- NAND_ECC_HW6_512 + + Hardware ECC generator providing 6 bytes ECC per 512 byte. + +- NAND_ECC_HW8_512 + + Hardware ECC generator providing 6 bytes ECC per 512 byte. + +If your hardware generator has a different functionality add it at the +appropriate place in nand_base.c + +The board driver must provide following functions: + +- enable_hwecc + + This function is called before reading / writing to the chip. Reset + or initialize the hardware generator in this function. The function + is called with an argument which let you distinguish between read and + write operations. + +- calculate_ecc + + This function is called after read / write from / to the chip. + Transfer the ECC from the hardware to the buffer. If the option + NAND_HWECC_SYNDROME is set then the function is only called on + write. See below. + +- correct_data + + In case of an ECC error this function is called for error detection + and correction. Return 1 respectively 2 in case the error can be + corrected. If the error is not correctable return -1. If your + hardware generator matches the default algorithm of the nand_ecc + software generator then use the correction function provided by + nand_ecc instead of implementing duplicated code. + +Hardware ECC with syndrome calculation +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Many hardware ECC implementations provide Reed-Solomon codes and +calculate an error syndrome on read. The syndrome must be converted to a +standard Reed-Solomon syndrome before calling the error correction code +in the generic Reed-Solomon library. + +The ECC bytes must be placed immediately after the data bytes in order +to make the syndrome generator work. This is contrary to the usual +layout used by software ECC. The separation of data and out of band area +is not longer possible. The nand driver code handles this layout and the +remaining free bytes in the oob area are managed by the autoplacement +code. Provide a matching oob-layout in this case. See rts_from4.c and +diskonchip.c for implementation reference. In those cases we must also +use bad block tables on FLASH, because the ECC layout is interfering +with the bad block marker positions. See bad block table support for +details. + +Bad block table support +----------------------- + +Most NAND chips mark the bad blocks at a defined position in the spare +area. Those blocks must not be erased under any circumstances as the bad +block information would be lost. It is possible to check the bad block +mark each time when the blocks are accessed by reading the spare area of +the first page in the block. This is time consuming so a bad block table +is used. + +The nand driver supports various types of bad block tables. + +- Per device + + The bad block table contains all bad block information of the device + which can consist of multiple chips. + +- Per chip + + A bad block table is used per chip and contains the bad block + information for this particular chip. + +- Fixed offset + + The bad block table is located at a fixed offset in the chip + (device). This applies to various DiskOnChip devices. + +- Automatic placed + + The bad block table is automatically placed and detected either at + the end or at the beginning of a chip (device) + +- Mirrored tables + + The bad block table is mirrored on the chip (device) to allow updates + of the bad block table without data loss. + +nand_scan() calls the function nand_default_bbt(). +nand_default_bbt() selects appropriate default bad block table +descriptors depending on the chip information which was retrieved by +nand_scan(). + +The standard policy is scanning the device for bad blocks and build a +ram based bad block table which allows faster access than always +checking the bad block information on the flash chip itself. + +Flash based tables +~~~~~~~~~~~~~~~~~~ + +It may be desired or necessary to keep a bad block table in FLASH. For +AG-AND chips this is mandatory, as they have no factory marked bad +blocks. They have factory marked good blocks. The marker pattern is +erased when the block is erased to be reused. So in case of powerloss +before writing the pattern back to the chip this block would be lost and +added to the bad blocks. Therefore we scan the chip(s) when we detect +them the first time for good blocks and store this information in a bad +block table before erasing any of the blocks. + +The blocks in which the tables are stored are protected against +accidental access by marking them bad in the memory bad block table. The +bad block table management functions are allowed to circumvent this +protection. + +The simplest way to activate the FLASH based bad block table support is +to set the option NAND_BBT_USE_FLASH in the bbt_option field of the +nand chip structure before calling nand_scan(). For AG-AND chips is +this done by default. This activates the default FLASH based bad block +table functionality of the NAND driver. The default bad block table +options are + +- Store bad block table per chip + +- Use 2 bits per block + +- Automatic placement at the end of the chip + +- Use mirrored tables with version numbers + +- Reserve 4 blocks at the end of the chip + +User defined tables +~~~~~~~~~~~~~~~~~~~ + +User defined tables are created by filling out a nand_bbt_descr +structure and storing the pointer in the nand_chip structure member +bbt_td before calling nand_scan(). If a mirror table is necessary a +second structure must be created and a pointer to this structure must be +stored in bbt_md inside the nand_chip structure. If the bbt_md member +is set to NULL then only the main table is used and no scan for the +mirrored table is performed. + +The most important field in the nand_bbt_descr structure is the +options field. The options define most of the table properties. Use the +predefined constants from nand.h to define the options. + +- Number of bits per block + + The supported number of bits is 1, 2, 4, 8. + +- Table per chip + + Setting the constant NAND_BBT_PERCHIP selects that a bad block + table is managed for each chip in a chip array. If this option is not + set then a per device bad block table is used. + +- Table location is absolute + + Use the option constant NAND_BBT_ABSPAGE and define the absolute + page number where the bad block table starts in the field pages. If + you have selected bad block tables per chip and you have a multi chip + array then the start page must be given for each chip in the chip + array. Note: there is no scan for a table ident pattern performed, so + the fields pattern, veroffs, offs, len can be left uninitialized + +- Table location is automatically detected + + The table can either be located in the first or the last good blocks + of the chip (device). Set NAND_BBT_LASTBLOCK to place the bad block + table at the end of the chip (device). The bad block tables are + marked and identified by a pattern which is stored in the spare area + of the first page in the block which holds the bad block table. Store + a pointer to the pattern in the pattern field. Further the length of + the pattern has to be stored in len and the offset in the spare area + must be given in the offs member of the nand_bbt_descr structure. + For mirrored bad block tables different patterns are mandatory. + +- Table creation + + Set the option NAND_BBT_CREATE to enable the table creation if no + table can be found during the scan. Usually this is done only once if + a new chip is found. + +- Table write support + + Set the option NAND_BBT_WRITE to enable the table write support. + This allows the update of the bad block table(s) in case a block has + to be marked bad due to wear. The MTD interface function + block_markbad is calling the update function of the bad block table. + If the write support is enabled then the table is updated on FLASH. + + Note: Write support should only be enabled for mirrored tables with + version control. + +- Table version control + + Set the option NAND_BBT_VERSION to enable the table version + control. It's highly recommended to enable this for mirrored tables + with write support. It makes sure that the risk of losing the bad + block table information is reduced to the loss of the information + about the one worn out block which should be marked bad. The version + is stored in 4 consecutive bytes in the spare area of the device. The + position of the version number is defined by the member veroffs in + the bad block table descriptor. + +- Save block contents on write + + In case that the block which holds the bad block table does contain + other useful information, set the option NAND_BBT_SAVECONTENT. When + the bad block table is written then the whole block is read the bad + block table is updated and the block is erased and everything is + written back. If this option is not set only the bad block table is + written and everything else in the block is ignored and erased. + +- Number of reserved blocks + + For automatic placement some blocks must be reserved for bad block + table storage. The number of reserved blocks is defined in the + maxblocks member of the bad block table description structure. + Reserving 4 blocks for mirrored tables should be a reasonable number. + This also limits the number of blocks which are scanned for the bad + block table ident pattern. + +Spare area (auto)placement +-------------------------- + +The nand driver implements different possibilities for placement of +filesystem data in the spare area, + +- Placement defined by fs driver + +- Automatic placement + +The default placement function is automatic placement. The nand driver +has built in default placement schemes for the various chiptypes. If due +to hardware ECC functionality the default placement does not fit then +the board driver can provide a own placement scheme. + +File system drivers can provide a own placement scheme which is used +instead of the default placement scheme. + +Placement schemes are defined by a nand_oobinfo structure + +:: + + struct nand_oobinfo { + int useecc; + int eccbytes; + int eccpos[24]; + int oobfree[8][2]; + }; + + +- useecc + + The useecc member controls the ecc and placement function. The header + file include/mtd/mtd-abi.h contains constants to select ecc and + placement. MTD_NANDECC_OFF switches off the ecc complete. This is + not recommended and available for testing and diagnosis only. + MTD_NANDECC_PLACE selects caller defined placement, + MTD_NANDECC_AUTOPLACE selects automatic placement. + +- eccbytes + + The eccbytes member defines the number of ecc bytes per page. + +- eccpos + + The eccpos array holds the byte offsets in the spare area where the + ecc codes are placed. + +- oobfree + + The oobfree array defines the areas in the spare area which can be + used for automatic placement. The information is given in the format + {offset, size}. offset defines the start of the usable area, size the + length in bytes. More than one area can be defined. The list is + terminated by an {0, 0} entry. + +Placement defined by fs driver +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The calling function provides a pointer to a nand_oobinfo structure +which defines the ecc placement. For writes the caller must provide a +spare area buffer along with the data buffer. The spare area buffer size +is (number of pages) \* (size of spare area). For reads the buffer size +is (number of pages) \* ((size of spare area) + (number of ecc steps per +page) \* sizeof (int)). The driver stores the result of the ecc check +for each tuple in the spare buffer. The storage sequence is:: + + <spare data page 0><ecc result 0>...<ecc result n> + + ... + + <spare data page n><ecc result 0>...<ecc result n> + +This is a legacy mode used by YAFFS1. + +If the spare area buffer is NULL then only the ECC placement is done +according to the given scheme in the nand_oobinfo structure. + +Automatic placement +~~~~~~~~~~~~~~~~~~~ + +Automatic placement uses the built in defaults to place the ecc bytes in +the spare area. If filesystem data have to be stored / read into the +spare area then the calling function must provide a buffer. The buffer +size per page is determined by the oobfree array in the nand_oobinfo +structure. + +If the spare area buffer is NULL then only the ECC placement is done +according to the default builtin scheme. + +Spare area autoplacement default schemes +---------------------------------------- + +256 byte pagesize +~~~~~~~~~~~~~~~~~ + +======== ================== =================================================== +Offset Content Comment +======== ================== =================================================== +0x00 ECC byte 0 Error correction code byte 0 +0x01 ECC byte 1 Error correction code byte 1 +0x02 ECC byte 2 Error correction code byte 2 +0x03 Autoplace 0 +0x04 Autoplace 1 +0x05 Bad block marker If any bit in this byte is zero, then this + block is bad. This applies only to the first + page in a block. In the remaining pages this + byte is reserved +0x06 Autoplace 2 +0x07 Autoplace 3 +======== ================== =================================================== + +512 byte pagesize +~~~~~~~~~~~~~~~~~ + + +============= ================== ============================================== +Offset Content Comment +============= ================== ============================================== +0x00 ECC byte 0 Error correction code byte 0 of the lower + 256 Byte data in this page +0x01 ECC byte 1 Error correction code byte 1 of the lower + 256 Bytes of data in this page +0x02 ECC byte 2 Error correction code byte 2 of the lower + 256 Bytes of data in this page +0x03 ECC byte 3 Error correction code byte 0 of the upper + 256 Bytes of data in this page +0x04 reserved reserved +0x05 Bad block marker If any bit in this byte is zero, then this + block is bad. This applies only to the first + page in a block. In the remaining pages this + byte is reserved +0x06 ECC byte 4 Error correction code byte 1 of the upper + 256 Bytes of data in this page +0x07 ECC byte 5 Error correction code byte 2 of the upper + 256 Bytes of data in this page +0x08 - 0x0F Autoplace 0 - 7 +============= ================== ============================================== + +2048 byte pagesize +~~~~~~~~~~~~~~~~~~ + +=========== ================== ================================================ +Offset Content Comment +=========== ================== ================================================ +0x00 Bad block marker If any bit in this byte is zero, then this block + is bad. This applies only to the first page in a + block. In the remaining pages this byte is + reserved +0x01 Reserved Reserved +0x02-0x27 Autoplace 0 - 37 +0x28 ECC byte 0 Error correction code byte 0 of the first + 256 Byte data in this page +0x29 ECC byte 1 Error correction code byte 1 of the first + 256 Bytes of data in this page +0x2A ECC byte 2 Error correction code byte 2 of the first + 256 Bytes data in this page +0x2B ECC byte 3 Error correction code byte 0 of the second + 256 Bytes of data in this page +0x2C ECC byte 4 Error correction code byte 1 of the second + 256 Bytes of data in this page +0x2D ECC byte 5 Error correction code byte 2 of the second + 256 Bytes of data in this page +0x2E ECC byte 6 Error correction code byte 0 of the third + 256 Bytes of data in this page +0x2F ECC byte 7 Error correction code byte 1 of the third + 256 Bytes of data in this page +0x30 ECC byte 8 Error correction code byte 2 of the third + 256 Bytes of data in this page +0x31 ECC byte 9 Error correction code byte 0 of the fourth + 256 Bytes of data in this page +0x32 ECC byte 10 Error correction code byte 1 of the fourth + 256 Bytes of data in this page +0x33 ECC byte 11 Error correction code byte 2 of the fourth + 256 Bytes of data in this page +0x34 ECC byte 12 Error correction code byte 0 of the fifth + 256 Bytes of data in this page +0x35 ECC byte 13 Error correction code byte 1 of the fifth + 256 Bytes of data in this page +0x36 ECC byte 14 Error correction code byte 2 of the fifth + 256 Bytes of data in this page +0x37 ECC byte 15 Error correction code byte 0 of the sixth + 256 Bytes of data in this page +0x38 ECC byte 16 Error correction code byte 1 of the sixth + 256 Bytes of data in this page +0x39 ECC byte 17 Error correction code byte 2 of the sixth + 256 Bytes of data in this page +0x3A ECC byte 18 Error correction code byte 0 of the seventh + 256 Bytes of data in this page +0x3B ECC byte 19 Error correction code byte 1 of the seventh + 256 Bytes of data in this page +0x3C ECC byte 20 Error correction code byte 2 of the seventh + 256 Bytes of data in this page +0x3D ECC byte 21 Error correction code byte 0 of the eighth + 256 Bytes of data in this page +0x3E ECC byte 22 Error correction code byte 1 of the eighth + 256 Bytes of data in this page +0x3F ECC byte 23 Error correction code byte 2 of the eighth + 256 Bytes of data in this page +=========== ================== ================================================ + +Filesystem support +================== + +The NAND driver provides all necessary functions for a filesystem via +the MTD interface. + +Filesystems must be aware of the NAND peculiarities and restrictions. +One major restrictions of NAND Flash is, that you cannot write as often +as you want to a page. The consecutive writes to a page, before erasing +it again, are restricted to 1-3 writes, depending on the manufacturers +specifications. This applies similar to the spare area. + +Therefore NAND aware filesystems must either write in page size chunks +or hold a writebuffer to collect smaller writes until they sum up to +pagesize. Available NAND aware filesystems: JFFS2, YAFFS. + +The spare area usage to store filesystem data is controlled by the spare +area placement functionality which is described in one of the earlier +chapters. + +Tools +===== + +The MTD project provides a couple of helpful tools to handle NAND Flash. + +- flasherase, flasheraseall: Erase and format FLASH partitions + +- nandwrite: write filesystem images to NAND FLASH + +- nanddump: dump the contents of a NAND FLASH partitions + +These tools are aware of the NAND restrictions. Please use those tools +instead of complaining about errors which are caused by non NAND aware +access methods. + +Constants +========= + +This chapter describes the constants which might be relevant for a +driver developer. + +Chip option constants +--------------------- + +Constants for chip id table +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +These constants are defined in nand.h. They are OR-ed together to +describe the chip functionality:: + + /* Buswitdh is 16 bit */ + #define NAND_BUSWIDTH_16 0x00000002 + /* Device supports partial programming without padding */ + #define NAND_NO_PADDING 0x00000004 + /* Chip has cache program function */ + #define NAND_CACHEPRG 0x00000008 + /* Chip has copy back function */ + #define NAND_COPYBACK 0x00000010 + /* AND Chip which has 4 banks and a confusing page / block + * assignment. See Renesas datasheet for further information */ + #define NAND_IS_AND 0x00000020 + /* Chip has a array of 4 pages which can be read without + * additional ready /busy waits */ + #define NAND_4PAGE_ARRAY 0x00000040 + + +Constants for runtime options +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +These constants are defined in nand.h. They are OR-ed together to +describe the functionality:: + + /* The hw ecc generator provides a syndrome instead a ecc value on read + * This can only work if we have the ecc bytes directly behind the + * data bytes. Applies for DOC and AG-AND Renesas HW Reed Solomon generators */ + #define NAND_HWECC_SYNDROME 0x00020000 + + +ECC selection constants +----------------------- + +Use these constants to select the ECC algorithm:: + + /* No ECC. Usage is not recommended ! */ + #define NAND_ECC_NONE 0 + /* Software ECC 3 byte ECC per 256 Byte data */ + #define NAND_ECC_SOFT 1 + /* Hardware ECC 3 byte ECC per 256 Byte data */ + #define NAND_ECC_HW3_256 2 + /* Hardware ECC 3 byte ECC per 512 Byte data */ + #define NAND_ECC_HW3_512 3 + /* Hardware ECC 6 byte ECC per 512 Byte data */ + #define NAND_ECC_HW6_512 4 + /* Hardware ECC 6 byte ECC per 512 Byte data */ + #define NAND_ECC_HW8_512 6 + + +Hardware control related constants +---------------------------------- + +These constants describe the requested hardware access function when the +boardspecific hardware control function is called:: + + /* Select the chip by setting nCE to low */ + #define NAND_CTL_SETNCE 1 + /* Deselect the chip by setting nCE to high */ + #define NAND_CTL_CLRNCE 2 + /* Select the command latch by setting CLE to high */ + #define NAND_CTL_SETCLE 3 + /* Deselect the command latch by setting CLE to low */ + #define NAND_CTL_CLRCLE 4 + /* Select the address latch by setting ALE to high */ + #define NAND_CTL_SETALE 5 + /* Deselect the address latch by setting ALE to low */ + #define NAND_CTL_CLRALE 6 + /* Set write protection by setting WP to high. Not used! */ + #define NAND_CTL_SETWP 7 + /* Clear write protection by setting WP to low. Not used! */ + #define NAND_CTL_CLRWP 8 + + +Bad block table related constants +--------------------------------- + +These constants describe the options used for bad block table +descriptors:: + + /* Options for the bad block table descriptors */ + + /* The number of bits used per block in the bbt on the device */ + #define NAND_BBT_NRBITS_MSK 0x0000000F + #define NAND_BBT_1BIT 0x00000001 + #define NAND_BBT_2BIT 0x00000002 + #define NAND_BBT_4BIT 0x00000004 + #define NAND_BBT_8BIT 0x00000008 + /* The bad block table is in the last good block of the device */ + #define NAND_BBT_LASTBLOCK 0x00000010 + /* The bbt is at the given page, else we must scan for the bbt */ + #define NAND_BBT_ABSPAGE 0x00000020 + /* bbt is stored per chip on multichip devices */ + #define NAND_BBT_PERCHIP 0x00000080 + /* bbt has a version counter at offset veroffs */ + #define NAND_BBT_VERSION 0x00000100 + /* Create a bbt if none axists */ + #define NAND_BBT_CREATE 0x00000200 + /* Write bbt if necessary */ + #define NAND_BBT_WRITE 0x00001000 + /* Read and write back block contents when writing bbt */ + #define NAND_BBT_SAVECONTENT 0x00002000 + + +Structures +========== + +This chapter contains the autogenerated documentation of the structures +which are used in the NAND driver and might be relevant for a driver +developer. Each struct member has a short description which is marked +with an [XXX] identifier. See the chapter "Documentation hints" for an +explanation. + +.. kernel-doc:: include/linux/mtd/nand.h + :internal: + +Public Functions Provided +========================= + +This chapter contains the autogenerated documentation of the NAND kernel +API functions which are exported. Each function has a short description +which is marked with an [XXX] identifier. See the chapter "Documentation +hints" for an explanation. + +.. kernel-doc:: drivers/mtd/nand/nand_base.c + :export: + +.. kernel-doc:: drivers/mtd/nand/nand_ecc.c + :export: + +Internal Functions Provided +=========================== + +This chapter contains the autogenerated documentation of the NAND driver +internal functions. Each function has a short description which is +marked with an [XXX] identifier. See the chapter "Documentation hints" +for an explanation. The functions marked with [DEFAULT] might be +relevant for a board driver developer. + +.. kernel-doc:: drivers/mtd/nand/nand_base.c + :internal: + +.. kernel-doc:: drivers/mtd/nand/nand_bbt.c + :internal: + +Credits +======= + +The following people have contributed to the NAND driver: + +1. Steven J. Hill\ sjhill@realitydiluted.com + +2. David Woodhouse\ dwmw2@infradead.org + +3. Thomas Gleixner\ tglx@linutronix.de + +A lot of users have provided bugfixes, improvements and helping hands +for testing. Thanks a lot. + +The following people have contributed to this document: + +1. Thomas Gleixner\ tglx@linutronix.de diff --git a/Documentation/driver-api/rapidio.rst b/Documentation/driver-api/rapidio.rst new file mode 100644 index 000000000000..71ff658ab78e --- /dev/null +++ b/Documentation/driver-api/rapidio.rst @@ -0,0 +1,107 @@ +======================= +RapidIO Subsystem Guide +======================= + +:Author: Matt Porter + +Introduction +============ + +RapidIO is a high speed switched fabric interconnect with features aimed +at the embedded market. RapidIO provides support for memory-mapped I/O +as well as message-based transactions over the switched fabric network. +RapidIO has a standardized discovery mechanism not unlike the PCI bus +standard that allows simple detection of devices in a network. + +This documentation is provided for developers intending to support +RapidIO on new architectures, write new drivers, or to understand the +subsystem internals. + +Known Bugs and Limitations +========================== + +Bugs +---- + +None. ;) + +Limitations +----------- + +1. Access/management of RapidIO memory regions is not supported + +2. Multiple host enumeration is not supported + +RapidIO driver interface +======================== + +Drivers are provided a set of calls in order to interface with the +subsystem to gather info on devices, request/map memory region +resources, and manage mailboxes/doorbells. + +Functions +--------- + +.. kernel-doc:: include/linux/rio_drv.h + :internal: + +.. kernel-doc:: drivers/rapidio/rio-driver.c + :export: + +.. kernel-doc:: drivers/rapidio/rio.c + :export: + +Internals +========= + +This chapter contains the autogenerated documentation of the RapidIO +subsystem. + +Structures +---------- + +.. kernel-doc:: include/linux/rio.h + :internal: + +Enumeration and Discovery +------------------------- + +.. kernel-doc:: drivers/rapidio/rio-scan.c + :internal: + +Driver functionality +-------------------- + +.. kernel-doc:: drivers/rapidio/rio.c + :internal: + +.. kernel-doc:: drivers/rapidio/rio-access.c + :internal: + +Device model support +-------------------- + +.. kernel-doc:: drivers/rapidio/rio-driver.c + :internal: + +PPC32 support +------------- + +.. kernel-doc:: arch/powerpc/sysdev/fsl_rio.c + :internal: + +Credits +======= + +The following people have contributed to the RapidIO subsystem directly +or indirectly: + +1. Matt Porter\ mporter@kernel.crashing.org + +2. Randy Vinson\ rvinson@mvista.com + +3. Dan Malek\ dan@embeddedalley.com + +The following people have contributed to this document: + +1. Matt Porter\ mporter@kernel.crashing.org diff --git a/Documentation/driver-api/s390-drivers.rst b/Documentation/driver-api/s390-drivers.rst new file mode 100644 index 000000000000..7060da136095 --- /dev/null +++ b/Documentation/driver-api/s390-drivers.rst @@ -0,0 +1,111 @@ +=================================== +Writing s390 channel device drivers +=================================== + +:Author: Cornelia Huck + +Introduction +============ + +This document describes the interfaces available for device drivers that +drive s390 based channel attached I/O devices. This includes interfaces +for interaction with the hardware and interfaces for interacting with +the common driver core. Those interfaces are provided by the s390 common +I/O layer. + +The document assumes a familarity with the technical terms associated +with the s390 channel I/O architecture. For a description of this +architecture, please refer to the "z/Architecture: Principles of +Operation", IBM publication no. SA22-7832. + +While most I/O devices on a s390 system are typically driven through the +channel I/O mechanism described here, there are various other methods +(like the diag interface). These are out of the scope of this document. + +Some additional information can also be found in the kernel source under +Documentation/s390/driver-model.txt. + +The ccw bus +=========== + +The ccw bus typically contains the majority of devices available to a +s390 system. Named after the channel command word (ccw), the basic +command structure used to address its devices, the ccw bus contains +so-called channel attached devices. They are addressed via I/O +subchannels, visible on the css bus. A device driver for +channel-attached devices, however, will never interact with the +subchannel directly, but only via the I/O device on the ccw bus, the ccw +device. + +I/O functions for channel-attached devices +------------------------------------------ + +Some hardware structures have been translated into C structures for use +by the common I/O layer and device drivers. For more information on the +hardware structures represented here, please consult the Principles of +Operation. + +.. kernel-doc:: arch/s390/include/asm/cio.h + :internal: + +ccw devices +----------- + +Devices that want to initiate channel I/O need to attach to the ccw bus. +Interaction with the driver core is done via the common I/O layer, which +provides the abstractions of ccw devices and ccw device drivers. + +The functions that initiate or terminate channel I/O all act upon a ccw +device structure. Device drivers must not bypass those functions or +strange side effects may happen. + +.. kernel-doc:: arch/s390/include/asm/ccwdev.h + :internal: + +.. kernel-doc:: drivers/s390/cio/device.c + :export: + +.. kernel-doc:: drivers/s390/cio/device_ops.c + :export: + +The channel-measurement facility +-------------------------------- + +The channel-measurement facility provides a means to collect measurement +data which is made available by the channel subsystem for each channel +attached device. + +.. kernel-doc:: arch/s390/include/asm/cmb.h + :internal: + +.. kernel-doc:: drivers/s390/cio/cmf.c + :export: + +The ccwgroup bus +================ + +The ccwgroup bus only contains artificial devices, created by the user. +Many networking devices (e.g. qeth) are in fact composed of several ccw +devices (like read, write and data channel for qeth). The ccwgroup bus +provides a mechanism to create a meta-device which contains those ccw +devices as slave devices and can be associated with the netdevice. + +ccw group devices +----------------- + +.. kernel-doc:: arch/s390/include/asm/ccwgroup.h + :internal: + +.. kernel-doc:: drivers/s390/cio/ccwgroup.c + :export: + +Generic interfaces +================== + +Some interfaces are available to other drivers that do not necessarily +have anything to do with the busses described above, but still are +indirectly using basic infrastructure in the common I/O layer. One +example is the support for adapter interrupts. + +.. kernel-doc:: drivers/s390/cio/airq.c + :export: diff --git a/Documentation/driver-api/scsi.rst b/Documentation/driver-api/scsi.rst new file mode 100644 index 000000000000..859fb672319f --- /dev/null +++ b/Documentation/driver-api/scsi.rst @@ -0,0 +1,344 @@ +===================== +SCSI Interfaces Guide +===================== + +:Author: James Bottomley +:Author: Rob Landley + +Introduction +============ + +Protocol vs bus +--------------- + +Once upon a time, the Small Computer Systems Interface defined both a +parallel I/O bus and a data protocol to connect a wide variety of +peripherals (disk drives, tape drives, modems, printers, scanners, +optical drives, test equipment, and medical devices) to a host computer. + +Although the old parallel (fast/wide/ultra) SCSI bus has largely fallen +out of use, the SCSI command set is more widely used than ever to +communicate with devices over a number of different busses. + +The `SCSI protocol <http://www.t10.org/scsi-3.htm>`__ is a big-endian +peer-to-peer packet based protocol. SCSI commands are 6, 10, 12, or 16 +bytes long, often followed by an associated data payload. + +SCSI commands can be transported over just about any kind of bus, and +are the default protocol for storage devices attached to USB, SATA, SAS, +Fibre Channel, FireWire, and ATAPI devices. SCSI packets are also +commonly exchanged over Infiniband, +`I20 <http://i2o.shadowconnect.com/faq.php>`__, TCP/IP +(`iSCSI <https://en.wikipedia.org/wiki/ISCSI>`__), even `Parallel +ports <http://cyberelk.net/tim/parport/parscsi.html>`__. + +Design of the Linux SCSI subsystem +---------------------------------- + +The SCSI subsystem uses a three layer design, with upper, mid, and low +layers. Every operation involving the SCSI subsystem (such as reading a +sector from a disk) uses one driver at each of the 3 levels: one upper +layer driver, one lower layer driver, and the SCSI midlayer. + +The SCSI upper layer provides the interface between userspace and the +kernel, in the form of block and char device nodes for I/O and ioctl(). +The SCSI lower layer contains drivers for specific hardware devices. + +In between is the SCSI mid-layer, analogous to a network routing layer +such as the IPv4 stack. The SCSI mid-layer routes a packet based data +protocol between the upper layer's /dev nodes and the corresponding +devices in the lower layer. It manages command queues, provides error +handling and power management functions, and responds to ioctl() +requests. + +SCSI upper layer +================ + +The upper layer supports the user-kernel interface by providing device +nodes. + +sd (SCSI Disk) +-------------- + +sd (sd_mod.o) + +sr (SCSI CD-ROM) +---------------- + +sr (sr_mod.o) + +st (SCSI Tape) +-------------- + +st (st.o) + +sg (SCSI Generic) +----------------- + +sg (sg.o) + +ch (SCSI Media Changer) +----------------------- + +ch (ch.c) + +SCSI mid layer +============== + +SCSI midlayer implementation +---------------------------- + +include/scsi/scsi_device.h +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: include/scsi/scsi_device.h + :internal: + +drivers/scsi/scsi.c +~~~~~~~~~~~~~~~~~~~ + +Main file for the SCSI midlayer. + +.. kernel-doc:: drivers/scsi/scsi.c + :export: + +drivers/scsi/scsicam.c +~~~~~~~~~~~~~~~~~~~~~~ + +`SCSI Common Access +Method <http://www.t10.org/ftp/t10/drafts/cam/cam-r12b.pdf>`__ support +functions, for use with HDIO_GETGEO, etc. + +.. kernel-doc:: drivers/scsi/scsicam.c + :export: + +drivers/scsi/scsi_error.c +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Common SCSI error/timeout handling routines. + +.. kernel-doc:: drivers/scsi/scsi_error.c + :export: + +drivers/scsi/scsi_devinfo.c +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Manage scsi_dev_info_list, which tracks blacklisted and whitelisted +devices. + +.. kernel-doc:: drivers/scsi/scsi_devinfo.c + :internal: + +drivers/scsi/scsi_ioctl.c +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Handle ioctl() calls for SCSI devices. + +.. kernel-doc:: drivers/scsi/scsi_ioctl.c + :export: + +drivers/scsi/scsi_lib.c +~~~~~~~~~~~~~~~~~~~~~~~~ + +SCSI queuing library. + +.. kernel-doc:: drivers/scsi/scsi_lib.c + :export: + +drivers/scsi/scsi_lib_dma.c +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +SCSI library functions depending on DMA (map and unmap scatter-gather +lists). + +.. kernel-doc:: drivers/scsi/scsi_lib_dma.c + :export: + +drivers/scsi/scsi_module.c +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The file drivers/scsi/scsi_module.c contains legacy support for +old-style host templates. It should never be used by any new driver. + +drivers/scsi/scsi_proc.c +~~~~~~~~~~~~~~~~~~~~~~~~~ + +The functions in this file provide an interface between the PROC file +system and the SCSI device drivers It is mainly used for debugging, +statistics and to pass information directly to the lowlevel driver. I.E. +plumbing to manage /proc/scsi/\* + +.. kernel-doc:: drivers/scsi/scsi_proc.c + :internal: + +drivers/scsi/scsi_netlink.c +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Infrastructure to provide async events from transports to userspace via +netlink, using a single NETLINK_SCSITRANSPORT protocol for all +transports. See `the original patch +submission <http://marc.info/?l=linux-scsi&m=115507374832500&w=2>`__ for +more details. + +.. kernel-doc:: drivers/scsi/scsi_netlink.c + :internal: + +drivers/scsi/scsi_scan.c +~~~~~~~~~~~~~~~~~~~~~~~~~ + +Scan a host to determine which (if any) devices are attached. The +general scanning/probing algorithm is as follows, exceptions are made to +it depending on device specific flags, compilation options, and global +variable (boot or module load time) settings. A specific LUN is scanned +via an INQUIRY command; if the LUN has a device attached, a scsi_device +is allocated and setup for it. For every id of every channel on the +given host, start by scanning LUN 0. Skip hosts that don't respond at +all to a scan of LUN 0. Otherwise, if LUN 0 has a device attached, +allocate and setup a scsi_device for it. If target is SCSI-3 or up, +issue a REPORT LUN, and scan all of the LUNs returned by the REPORT LUN; +else, sequentially scan LUNs up until some maximum is reached, or a LUN +is seen that cannot have a device attached to it. + +.. kernel-doc:: drivers/scsi/scsi_scan.c + :internal: + +drivers/scsi/scsi_sysctl.c +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Set up the sysctl entry: "/dev/scsi/logging_level" +(DEV_SCSI_LOGGING_LEVEL) which sets/returns scsi_logging_level. + +drivers/scsi/scsi_sysfs.c +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +SCSI sysfs interface routines. + +.. kernel-doc:: drivers/scsi/scsi_sysfs.c + :export: + +drivers/scsi/hosts.c +~~~~~~~~~~~~~~~~~~~~ + +mid to lowlevel SCSI driver interface + +.. kernel-doc:: drivers/scsi/hosts.c + :export: + +drivers/scsi/constants.c +~~~~~~~~~~~~~~~~~~~~~~~~ + +mid to lowlevel SCSI driver interface + +.. kernel-doc:: drivers/scsi/constants.c + :export: + +Transport classes +----------------- + +Transport classes are service libraries for drivers in the SCSI lower +layer, which expose transport attributes in sysfs. + +Fibre Channel transport +~~~~~~~~~~~~~~~~~~~~~~~ + +The file drivers/scsi/scsi_transport_fc.c defines transport attributes +for Fibre Channel. + +.. kernel-doc:: drivers/scsi/scsi_transport_fc.c + :export: + +iSCSI transport class +~~~~~~~~~~~~~~~~~~~~~ + +The file drivers/scsi/scsi_transport_iscsi.c defines transport +attributes for the iSCSI class, which sends SCSI packets over TCP/IP +connections. + +.. kernel-doc:: drivers/scsi/scsi_transport_iscsi.c + :export: + +Serial Attached SCSI (SAS) transport class +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The file drivers/scsi/scsi_transport_sas.c defines transport +attributes for Serial Attached SCSI, a variant of SATA aimed at large +high-end systems. + +The SAS transport class contains common code to deal with SAS HBAs, an +aproximated representation of SAS topologies in the driver model, and +various sysfs attributes to expose these topologies and management +interfaces to userspace. + +In addition to the basic SCSI core objects this transport class +introduces two additional intermediate objects: The SAS PHY as +represented by struct sas_phy defines an "outgoing" PHY on a SAS HBA or +Expander, and the SAS remote PHY represented by struct sas_rphy defines +an "incoming" PHY on a SAS Expander or end device. Note that this is +purely a software concept, the underlying hardware for a PHY and a +remote PHY is the exactly the same. + +There is no concept of a SAS port in this code, users can see what PHYs +form a wide port based on the port_identifier attribute, which is the +same for all PHYs in a port. + +.. kernel-doc:: drivers/scsi/scsi_transport_sas.c + :export: + +SATA transport class +~~~~~~~~~~~~~~~~~~~~ + +The SATA transport is handled by libata, which has its own book of +documentation in this directory. + +Parallel SCSI (SPI) transport class +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The file drivers/scsi/scsi_transport_spi.c defines transport +attributes for traditional (fast/wide/ultra) SCSI busses. + +.. kernel-doc:: drivers/scsi/scsi_transport_spi.c + :export: + +SCSI RDMA (SRP) transport class +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The file drivers/scsi/scsi_transport_srp.c defines transport +attributes for SCSI over Remote Direct Memory Access. + +.. kernel-doc:: drivers/scsi/scsi_transport_srp.c + :export: + +SCSI lower layer +================ + +Host Bus Adapter transport types +-------------------------------- + +Many modern device controllers use the SCSI command set as a protocol to +communicate with their devices through many different types of physical +connections. + +In SCSI language a bus capable of carrying SCSI commands is called a +"transport", and a controller connecting to such a bus is called a "host +bus adapter" (HBA). + +Debug transport +~~~~~~~~~~~~~~~ + +The file drivers/scsi/scsi_debug.c simulates a host adapter with a +variable number of disks (or disk like devices) attached, sharing a +common amount of RAM. Does a lot of checking to make sure that we are +not getting blocks mixed up, and panics the kernel if anything out of +the ordinary is seen. + +To be more realistic, the simulated devices have the transport +attributes of SAS disks. + +For documentation see http://sg.danny.cz/sg/sdebug26.html + +todo +~~~~ + +Parallel (fast/wide/ultra) SCSI, USB, SATA, SAS, Fibre Channel, +FireWire, ATAPI devices, Infiniband, I20, iSCSI, Parallel ports, +netlink... diff --git a/Documentation/driver-api/usb/dwc3.rst b/Documentation/driver-api/usb/dwc3.rst new file mode 100644 index 000000000000..c3dc84a50ce5 --- /dev/null +++ b/Documentation/driver-api/usb/dwc3.rst @@ -0,0 +1,712 @@ +=============================================================== +Synopsys DesignWare Core SuperSpeed USB 3.0 Controller +=============================================================== + +:Author: Felipe Balbi <felipe.balbi@linux.intel.com> +:Date: April 2017 + +Introduction +============ + +The *Synopsys DesignWare Core SuperSpeed USB 3.0 Controller* +(hereinafter referred to as *DWC3*) is a USB SuperSpeed compliant +controller which can be configured in one of 4 ways: + + 1. Peripheral-only configuration + 2. Host-only configuration + 3. Dual-Role configuration + 4. Hub configuration + +Linux currently supports several versions of this controller. In all +likelyhood, the version in your SoC is already supported. At the time +of this writing, known tested versions range from 2.02a to 3.10a. As a +rule of thumb, anything above 2.02a should work reliably well. + +Currently, we have many known users for this driver. In alphabetical +order: + + 1. Cavium + 2. Intel Corporation + 3. Qualcomm + 4. Rockchip + 5. ST + 6. Samsung + 7. Texas Instruments + 8. Xilinx + +Summary of Features +====================== + +For details about features supported by your version of DWC3, consult +your IP team and/or *Synopsys DesignWare Core SuperSpeed USB 3.0 +Controller Databook*. Following is a list of features supported by the +driver at the time of this writing: + + 1. Up to 16 bidirectional endpoints (including the control + pipe - ep0) + 2. Flexible endpoint configuration + 3. Simultaneous IN and OUT transfer support + 4. Scatter-list support + 5. Up to 256 TRBs [#trb]_ per endpoint + 6. Support for all transfer types (*Control*, *Bulk*, + *Interrupt*, and *Isochronous*) + 7. SuperSpeed Bulk Streams + 8. Link Power Management + 9. Trace Events for debugging + 10. DebugFS [#debugfs]_ interface + +These features have all been exercised with many of the **in-tree** +gadget drivers. We have verified both *ConfigFS* [#configfs]_ and +legacy gadget drivers. + +Driver Design +============== + +The DWC3 driver sits on the *drivers/usb/dwc3/* directory. All files +related to this driver are in this one directory. This makes it easy +for new-comers to read the code and understand how it behaves. + +Because of DWC3's configuration flexibility, the driver is a little +complex in some places but it should be rather straightforward to +understand. + +The biggest part of the driver refers to the Gadget API. + +Known Limitations +=================== + +Like any other HW, DWC3 has its own set of limitations. To avoid +constant questions about such problems, we decided to document them +here and have a single location to where we could point users. + +OUT Transfer Size Requirements +--------------------------------- + +According to Synopsys Databook, all OUT transfer TRBs [#trb]_ must +have their *size* field set to a value which is integer divisible by +the endpoint's *wMaxPacketSize*. This means that *e.g.* in order to +receive a Mass Storage *CBW* [#cbw]_, req->length must either be set +to a value that's divisible by *wMaxPacketSize* (1024 on SuperSpeed, +512 on HighSpeed, etc), or DWC3 driver must add a Chained TRB pointing +to a throw-away buffer for the remaining length. Without this, OUT +transfers will **NOT** start. + +Note that as of this writing, this won't be a problem because DWC3 is +fully capable of appending a chained TRB for the remaining length and +completely hide this detail from the gadget driver. It's still worth +mentioning because this seems to be the largest source of queries +about DWC3 and *non-working transfers*. + +TRB Ring Size Limitation +------------------------- + +We, currently, have a hard limit of 256 TRBs [#trb]_ per endpoint, +with the last TRB being a Link TRB [#link_trb]_ pointing back to the +first. This limit is arbitrary but it has the benefit of adding up to +exactly 4096 bytes, or 1 Page. + +DWC3 driver will try its best to cope with more than 255 requests and, +for the most part, it should work normally. However this is not +something that has been exercised very frequently. If you experience +any problems, see section **Reporting Bugs** below. + +Reporting Bugs +================ + +Whenever you encounter a problem with DWC3, first and foremost you +should make sure that: + + 1. You're running latest tag from `Linus' tree`_ + 2. You can reproduce the error without any out-of-tree changes + to DWC3 + 3. You have checked that it's not a fault on the host machine + +After all these are verified, then here's how to capture enough +information so we can be of any help to you. + +Required Information +--------------------- + +DWC3 relies exclusively on Trace Events for debugging. Everything is +exposed there, with some extra bits being exposed to DebugFS +[#debugfs]_. + +In order to capture DWC3's Trace Events you should run the following +commands **before** plugging the USB cable to a host machine: + +.. code-block:: sh + + # mkdir -p /d + # mkdir -p /t + # mount -t debugfs none /d + # mount -t tracefs none /t + # echo 81920 > /t/buffer_size_kb + # echo 1 > /t/events/dwc3/enable + +After this is done, you can connect your USB cable and reproduce the +problem. As soon as the fault is reproduced, make a copy of files +``trace`` and ``regdump``, like so: + +.. code-block:: sh + + # cp /t/trace /root/trace.txt + # cat /d/*dwc3*/regdump > /root/regdump.txt + +Make sure to compress ``trace.txt`` and ``regdump.txt`` in a tarball +and email it to `me`_ with `linux-usb`_ in Cc. If you want to be extra +sure that I'll help you, write your subject line in the following +format: + + **[BUG REPORT] usb: dwc3: Bug while doing XYZ** + +On the email body, make sure to detail what you doing, which gadget +driver you were using, how to reproduce the problem, what SoC you're +using, which OS (and its version) was running on the Host machine. + +With all this information, we should be able to understand what's +going on and be helpful to you. + +Debugging +=========== + +First and foremost a disclaimer:: + + DISCLAIMER: The information available on DebugFS and/or TraceFS can + change at any time at any Major Linux Kernel Release. If writing + scripts, do **NOT** assume information to be available in the + current format. + +With that out of the way, let's carry on. + +If you're willing to debug your own problem, you deserve a round of +applause :-) + +Anyway, there isn't much to say here other than Trace Events will be +really helpful in figuring out issues with DWC3. Also, access to +Synopsys Databook will be **really** valuable in this case. + +A USB Sniffer can be helpful at times but it's not entirely required, +there's a lot that can be understood without looking at the wire. + +Feel free to email `me`_ and Cc `linux-usb`_ if you need any help. + +``DebugFS`` +------------- + +``DebugFS`` is very good for gathering snapshots of what's going on +with DWC3 and/or any endpoint. + +On DWC3's ``DebugFS`` directory, you will find the following files and +directories: + +``ep[0..15]{in,out}/`` +``link_state`` +``regdump`` +``testmode`` + +``link_state`` +`````````````` + +When read, ``link_state`` will print out one of ``U0``, ``U1``, +``U2``, ``U3``, ``SS.Disabled``, ``RX.Detect``, ``SS.Inactive``, +``Polling``, ``Recovery``, ``Hot Reset``, ``Compliance``, +``Loopback``, ``Reset``, ``Resume`` or ``UNKNOWN link state``. + +This file can also be written to in order to force link to one of the +states above. + +``regdump`` +````````````` + +File name is self-explanatory. When read, ``regdump`` will print out a +register dump of DWC3. Note that this file can be grepped to find the +information you want. + +``testmode`` +`````````````` + +When read, ``testmode`` will print out a name of one of the specified +USB 2.0 Testmodes (``test_j``, ``test_k``, ``test_se0_nak``, +``test_packet``, ``test_force_enable``) or the string ``no test`` in +case no tests are currently being executed. + +In order to start any of these test modes, the same strings can be +written to the file and DWC3 will enter the requested test mode. + + +``ep[0..15]{in,out}`` +`````````````````````` + +For each endpoint we expose one directory following the naming +convention ``ep$num$dir`` *(ep0in, ep0out, ep1in, ...)*. Inside each +of these directories you will find the following files: + +``descriptor_fetch_queue`` +``event_queue`` +``rx_fifo_queue`` +``rx_info_queue`` +``rx_request_queue`` +``transfer_type`` +``trb_ring`` +``tx_fifo_queue`` +``tx_request_queue`` + +With access to Synopsys Databook, you can decode the information on +them. + +``transfer_type`` +~~~~~~~~~~~~~~~~~~ + +When read, ``transfer_type`` will print out one of ``control``, +``bulk``, ``interrupt`` or ``isochronous`` depending on what the +endpoint descriptor says. If the endpoint hasn't been enabled yet, it +will print ``--``. + +``trb_ring`` +~~~~~~~~~~~~~ + +When read, ``trb_ring`` will print out details about all TRBs on the +ring. It will also tell you where our enqueue and dequeue pointers are +located in the ring: + +.. code-block:: sh + + buffer_addr,size,type,ioc,isp_imi,csp,chn,lst,hwo + 000000002c754000,481,normal,1,0,1,0,0,0 + 000000002c75c000,481,normal,1,0,1,0,0,0 + 000000002c780000,481,normal,1,0,1,0,0,0 + 000000002c788000,481,normal,1,0,1,0,0,0 + 000000002c78c000,481,normal,1,0,1,0,0,0 + 000000002c754000,481,normal,1,0,1,0,0,0 + 000000002c75c000,481,normal,1,0,1,0,0,0 + 000000002c784000,481,normal,1,0,1,0,0,0 + 000000002c788000,481,normal,1,0,1,0,0,0 + 000000002c78c000,481,normal,1,0,1,0,0,0 + 000000002c790000,481,normal,1,0,1,0,0,0 + 000000002c758000,481,normal,1,0,1,0,0,0 + 000000002c780000,481,normal,1,0,1,0,0,0 + 000000002c788000,481,normal,1,0,1,0,0,0 + 000000002c790000,481,normal,1,0,1,0,0,0 + 000000002c758000,481,normal,1,0,1,0,0,0 + 000000002c780000,481,normal,1,0,1,0,0,0 + 000000002c784000,481,normal,1,0,1,0,0,0 + 000000002c788000,481,normal,1,0,1,0,0,0 + 000000002c78c000,481,normal,1,0,1,0,0,0 + 000000002c754000,481,normal,1,0,1,0,0,0 + 000000002c758000,481,normal,1,0,1,0,0,0 + 000000002c780000,481,normal,1,0,1,0,0,0 + 000000002c784000,481,normal,1,0,1,0,0,0 + 000000002c78c000,481,normal,1,0,1,0,0,0 + 000000002c790000,481,normal,1,0,1,0,0,0 + 000000002c758000,481,normal,1,0,1,0,0,0 + 000000002c780000,481,normal,1,0,1,0,0,0 + 000000002c788000,481,normal,1,0,1,0,0,0 + 000000002c790000,481,normal,1,0,1,0,0,0 + 000000002c758000,481,normal,1,0,1,0,0,0 + 000000002c780000,481,normal,1,0,1,0,0,0 + 000000002c788000,481,normal,1,0,1,0,0,0 + 000000002c790000,481,normal,1,0,1,0,0,0 + 000000002c758000,481,normal,1,0,1,0,0,0 + 000000002c780000,481,normal,1,0,1,0,0,0 + 000000002c788000,481,normal,1,0,1,0,0,0 + 000000002c790000,481,normal,1,0,1,0,0,0 + 000000002c758000,481,normal,1,0,1,0,0,0 + 000000002c780000,481,normal,1,0,1,0,0,0 + 000000002c788000,481,normal,1,0,1,0,0,0 + 000000002c790000,481,normal,1,0,1,0,0,0 + 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0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 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0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 0000000000000000,0,UNKNOWN,0,0,0,0,0,0 + 00000000381ab000,0,link,0,0,0,0,0,1 + + +Trace Events +------------- + +DWC3 also provides several trace events which help us gathering +information about the behavior of the driver during runtime. + +In order to use these events, you must enable ``CONFIG_FTRACE`` in +your kernel config. + +For details about how enable DWC3 events, see section **Reporting +Bugs**. + +The following subsections will give details about each Event Class and +each Event defined by DWC3. + +MMIO +``````` + +It is sometimes useful to look at every MMIO access when looking for +bugs. Because of that, DWC3 offers two Trace Events (one for +dwc3_readl() and one for dwc3_writel()). ``TP_printk`` follows:: + + TP_printk("addr %p value %08x", __entry->base + __entry->offset, + __entry->value) + +Interrupt Events +```````````````` + +Every IRQ event can be logged and decoded into a human readable +string. Because every event will be different, we don't give an +example other than the ``TP_printk`` format used:: + + TP_printk("event (%08x): %s", __entry->event, + dwc3_decode_event(__entry->event, __entry->ep0state)) + +Control Request +````````````````` + +Every USB Control Request can be logged to the trace buffer. The +output format is:: + + TP_printk("%s", dwc3_decode_ctrl(__entry->bRequestType, + __entry->bRequest, __entry->wValue, + __entry->wIndex, __entry->wLength) + ) + +Note that Standard Control Requests will be decoded into +human-readable strings with their respective arguments. Class and +Vendor requests will be printed out a sequence of 8 bytes in hex +format. + +Lifetime of a ``struct usb_request`` +``````````````````````````````````````` + +The entire lifetime of a ``struct usb_request`` can be tracked on the +trace buffer. We have one event for each of allocation, free, +queueing, dequeueing, and giveback. Output format is:: + + TP_printk("%s: req %p length %u/%u %s%s%s ==> %d", + __get_str(name), __entry->req, __entry->actual, __entry->length, + __entry->zero ? "Z" : "z", + __entry->short_not_ok ? "S" : "s", + __entry->no_interrupt ? "i" : "I", + __entry->status + ) + +Generic Commands +```````````````````` + +We can log and decode every Generic Command with its completion +code. Format is:: + + TP_printk("cmd '%s' [%x] param %08x --> status: %s", + dwc3_gadget_generic_cmd_string(__entry->cmd), + __entry->cmd, __entry->param, + dwc3_gadget_generic_cmd_status_string(__entry->status) + ) + +Endpoint Commands +```````````````````` + +Endpoints commands can also be logged together with completion +code. Format is:: + + TP_printk("%s: cmd '%s' [%d] params %08x %08x %08x --> status: %s", + __get_str(name), dwc3_gadget_ep_cmd_string(__entry->cmd), + __entry->cmd, __entry->param0, + __entry->param1, __entry->param2, + dwc3_ep_cmd_status_string(__entry->cmd_status) + ) + +Lifetime of a ``TRB`` +`````````````````````` + +A ``TRB`` Lifetime is simple. We are either preparing a ``TRB`` or +completing it. With these two events, we can see how a ``TRB`` changes +over time. Format is:: + + TP_printk("%s: %d/%d trb %p buf %08x%08x size %s%d ctrl %08x (%c%c%c%c:%c%c:%s)", + __get_str(name), __entry->queued, __entry->allocated, + __entry->trb, __entry->bph, __entry->bpl, + ({char *s; + int pcm = ((__entry->size >> 24) & 3) + 1; + switch (__entry->type) { + case USB_ENDPOINT_XFER_INT: + case USB_ENDPOINT_XFER_ISOC: + switch (pcm) { + case 1: + s = "1x "; + break; + case 2: + s = "2x "; + break; + case 3: + s = "3x "; + break; + } + default: + s = ""; + } s; }), + DWC3_TRB_SIZE_LENGTH(__entry->size), __entry->ctrl, + __entry->ctrl & DWC3_TRB_CTRL_HWO ? 'H' : 'h', + __entry->ctrl & DWC3_TRB_CTRL_LST ? 'L' : 'l', + __entry->ctrl & DWC3_TRB_CTRL_CHN ? 'C' : 'c', + __entry->ctrl & DWC3_TRB_CTRL_CSP ? 'S' : 's', + __entry->ctrl & DWC3_TRB_CTRL_ISP_IMI ? 'S' : 's', + __entry->ctrl & DWC3_TRB_CTRL_IOC ? 'C' : 'c', + dwc3_trb_type_string(DWC3_TRBCTL_TYPE(__entry->ctrl)) + ) + +Lifetime of an Endpoint +``````````````````````` + +And endpoint's lifetime is summarized with enable and disable +operations, both of which can be traced. Format is:: + + TP_printk("%s: mps %d/%d streams %d burst %d ring %d/%d flags %c:%c%c%c%c%c:%c:%c", + __get_str(name), __entry->maxpacket, + __entry->maxpacket_limit, __entry->max_streams, + __entry->maxburst, __entry->trb_enqueue, + __entry->trb_dequeue, + __entry->flags & DWC3_EP_ENABLED ? 'E' : 'e', + __entry->flags & DWC3_EP_STALL ? 'S' : 's', + __entry->flags & DWC3_EP_WEDGE ? 'W' : 'w', + __entry->flags & DWC3_EP_BUSY ? 'B' : 'b', + __entry->flags & DWC3_EP_PENDING_REQUEST ? 'P' : 'p', + __entry->flags & DWC3_EP_MISSED_ISOC ? 'M' : 'm', + __entry->flags & DWC3_EP_END_TRANSFER_PENDING ? 'E' : 'e', + __entry->direction ? '<' : '>' + ) + + +Structures, Methods and Definitions +==================================== + +.. kernel-doc:: drivers/usb/dwc3/core.h + :doc: main data structures + :internal: + +.. kernel-doc:: drivers/usb/dwc3/gadget.h + :doc: gadget-only helpers + :internal: + +.. kernel-doc:: drivers/usb/dwc3/gadget.c + :doc: gadget-side implementation + :internal: + +.. kernel-doc:: drivers/usb/dwc3/core.c + :doc: core driver (probe, PM, etc) + :internal: + +.. [#trb] Transfer Request Block +.. [#link_trb] Transfer Request Block pointing to another Transfer + Request Block. +.. [#debugfs] The Debug File System +.. [#configfs] The Config File System +.. [#cbw] Command Block Wrapper +.. _Linus' tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ +.. _me: felipe.balbi@linux.intel.com +.. _linux-usb: linux-usb@vger.kernel.org diff --git a/Documentation/driver-api/usb/index.rst b/Documentation/driver-api/usb/index.rst index 1bf64edc8c8a..8fe995a1ec94 100644 --- a/Documentation/driver-api/usb/index.rst +++ b/Documentation/driver-api/usb/index.rst @@ -16,7 +16,10 @@ Linux USB API persist error-codes writing_usb_driver + dwc3 writing_musb_glue_layer + typec + usb3-debug-port .. only:: subproject and html diff --git a/Documentation/usb/typec.rst b/Documentation/driver-api/usb/typec.rst index b67a46779de9..8a7249f2ff04 100644 --- a/Documentation/usb/typec.rst +++ b/Documentation/driver-api/usb/typec.rst @@ -114,8 +114,7 @@ the details during registration. The class offers the following API for registering/unregistering cables and their plugs: .. kernel-doc:: drivers/usb/typec/typec.c - :functions: typec_register_cable typec_unregister_cable typec_register_plug - typec_unregister_plug + :functions: typec_register_cable typec_unregister_cable typec_register_plug typec_unregister_plug The class will provide a handle to struct typec_cable and struct typec_plug if the registration is successful, or NULL if it isn't. @@ -137,8 +136,7 @@ during connection of a partner or cable, the port driver must use the following APIs to report it to the class: .. kernel-doc:: drivers/usb/typec/typec.c - :functions: typec_set_data_role typec_set_pwr_role typec_set_vconn_role - typec_set_pwr_opmode + :functions: typec_set_data_role typec_set_pwr_role typec_set_vconn_role typec_set_pwr_opmode Alternate Modes ~~~~~~~~~~~~~~~ diff --git a/Documentation/usb/usb3-debug-port.rst b/Documentation/driver-api/usb/usb3-debug-port.rst index feb1a36a65b7..feb1a36a65b7 100644 --- a/Documentation/usb/usb3-debug-port.rst +++ b/Documentation/driver-api/usb/usb3-debug-port.rst diff --git a/Documentation/driver-api/w1.rst b/Documentation/driver-api/w1.rst new file mode 100644 index 000000000000..9963cca788a1 --- /dev/null +++ b/Documentation/driver-api/w1.rst @@ -0,0 +1,70 @@ +====================== +W1: Dallas' 1-wire bus +====================== + +:Author: David Fries + +W1 API internal to the kernel +============================= + +W1 API internal to the kernel +----------------------------- + +include/linux/w1.h +~~~~~~~~~~~~~~~~~~ + +W1 kernel API functions. + +.. kernel-doc:: include/linux/w1.h + :internal: + +drivers/w1/w1.c +~~~~~~~~~~~~~~~ + +W1 core functions. + +.. kernel-doc:: drivers/w1/w1.c + :internal: + +drivers/w1/w1_family.c +~~~~~~~~~~~~~~~~~~~~~~~ + +Allows registering device family operations. + +.. kernel-doc:: drivers/w1/w1_family.c + :export: + +drivers/w1/w1_internal.h +~~~~~~~~~~~~~~~~~~~~~~~~ + +W1 internal initialization for master devices. + +.. kernel-doc:: drivers/w1/w1_internal.h + :internal: + +drivers/w1/w1_int.c +~~~~~~~~~~~~~~~~~~~~ + +W1 internal initialization for master devices. + +.. kernel-doc:: drivers/w1/w1_int.c + :export: + +drivers/w1/w1_netlink.h +~~~~~~~~~~~~~~~~~~~~~~~~ + +W1 external netlink API structures and commands. + +.. kernel-doc:: drivers/w1/w1_netlink.h + :internal: + +drivers/w1/w1_io.c +~~~~~~~~~~~~~~~~~~~ + +W1 input/output. + +.. kernel-doc:: drivers/w1/w1_io.c + :export: + +.. kernel-doc:: drivers/w1/w1_io.c + :internal: diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt index e72587fe477d..2d132fcea0f8 100644 --- a/Documentation/driver-model/devres.txt +++ b/Documentation/driver-model/devres.txt @@ -311,6 +311,8 @@ IRQ devm_irq_alloc_desc_at() devm_irq_alloc_desc_from() devm_irq_alloc_descs_from() + devm_irq_alloc_generic_chip() + devm_irq_setup_generic_chip() LED devm_led_classdev_register() @@ -335,7 +337,12 @@ MEM devm_kzalloc() MFD - devm_mfd_add_devices() + devm_mfd_add_devices() + +MUX + devm_mux_chip_alloc() + devm_mux_chip_register() + devm_mux_control_get() PER-CPU MEM devm_alloc_percpu() diff --git a/Documentation/fb/api.txt b/Documentation/fb/api.txt index d4ff7de85700..d52cf1e3b975 100644 --- a/Documentation/fb/api.txt +++ b/Documentation/fb/api.txt @@ -289,12 +289,12 @@ the FB_CAP_FOURCC bit in the fb_fix_screeninfo capabilities field. FOURCC definitions are located in the linux/videodev2.h header. However, and despite starting with the V4L2_PIX_FMT_prefix, they are not restricted to V4L2 and don't require usage of the V4L2 subsystem. FOURCC documentation is -available in Documentation/DocBook/v4l/pixfmt.xml. +available in Documentation/media/uapi/v4l/pixfmt.rst. To select a format, applications set the grayscale field to the desired FOURCC. For YUV formats, they should also select the appropriate colorspace by setting the colorspace field to one of the colorspaces listed in linux/videodev2.h and -documented in Documentation/DocBook/v4l/colorspaces.xml. +documented in Documentation/media/uapi/v4l/colorspaces.rst. The red, green, blue and transp fields are not used with the FOURCC-based API. For forward compatibility reasons applications must zero those fields, and diff --git a/Documentation/filesystems/autofs4.txt b/Documentation/filesystems/autofs4.txt index f10dd590f69f..8444dc3d57e8 100644 --- a/Documentation/filesystems/autofs4.txt +++ b/Documentation/filesystems/autofs4.txt @@ -316,7 +316,7 @@ For version 5, the format of the message is: struct autofs_v5_packet { int proto_version; /* Protocol version */ int type; /* Type of packet */ - autofs_wqt_t wait_queue_token; + autofs_wqt_t wait_queue_entry_token; __u32 dev; __u64 ino; __u32 uid; @@ -341,12 +341,12 @@ The pipe will be set to "packet mode" (equivalent to passing `O_DIRECT`) to _pipe2(2)_ so that a read from the pipe will return at most one packet, and any unread portion of a packet will be discarded. -The `wait_queue_token` is a unique number which can identify a +The `wait_queue_entry_token` is a unique number which can identify a particular request to be acknowledged. When a message is sent over the pipe the affected dentry is marked as either "active" or "expiring" and other accesses to it block until the message is acknowledged using one of the ioctls below and the relevant -`wait_queue_token`. +`wait_queue_entry_token`. Communicating with autofs: root directory ioctls ------------------------------------------------ @@ -358,7 +358,7 @@ capability, or must be the automount daemon. The available ioctl commands are: - **AUTOFS_IOC_READY**: a notification has been handled. The argument - to the ioctl command is the "wait_queue_token" number + to the ioctl command is the "wait_queue_entry_token" number corresponding to the notification being acknowledged. - **AUTOFS_IOC_FAIL**: similar to above, but indicates failure with the error code `ENOENT`. @@ -382,14 +382,14 @@ The available ioctl commands are: struct autofs_packet_expire_multi { int proto_version; /* Protocol version */ int type; /* Type of packet */ - autofs_wqt_t wait_queue_token; + autofs_wqt_t wait_queue_entry_token; int len; char name[NAME_MAX+1]; }; is required. This is filled in with the name of something that can be unmounted or removed. If nothing can be expired, - `errno` is set to `EAGAIN`. Even though a `wait_queue_token` + `errno` is set to `EAGAIN`. Even though a `wait_queue_entry_token` is present in the structure, no "wait queue" is established and no acknowledgment is needed. - **AUTOFS_IOC_EXPIRE_MULTI**: This is similar to diff --git a/Documentation/filesystems/conf.py b/Documentation/filesystems/conf.py new file mode 100644 index 000000000000..ea44172af5c4 --- /dev/null +++ b/Documentation/filesystems/conf.py @@ -0,0 +1,10 @@ +# -*- coding: utf-8; mode: python -*- + +project = "Linux Filesystems API" + +tags.add("subproject") + +latex_documents = [ + ('index', 'filesystems.tex', project, + 'The kernel development community', 'manual'), +] diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst new file mode 100644 index 000000000000..256e10eedba4 --- /dev/null +++ b/Documentation/filesystems/index.rst @@ -0,0 +1,317 @@ +===================== +Linux Filesystems API +===================== + +The Linux VFS +============= + +The Filesystem types +-------------------- + +.. kernel-doc:: include/linux/fs.h + :internal: + +The Directory Cache +------------------- + +.. kernel-doc:: fs/dcache.c + :export: + +.. kernel-doc:: include/linux/dcache.h + :internal: + +Inode Handling +-------------- + +.. kernel-doc:: fs/inode.c + :export: + +.. kernel-doc:: fs/bad_inode.c + :export: + +Registration and Superblocks +---------------------------- + +.. kernel-doc:: fs/super.c + :export: + +File Locks +---------- + +.. kernel-doc:: fs/locks.c + :export: + +.. kernel-doc:: fs/locks.c + :internal: + +Other Functions +--------------- + +.. kernel-doc:: fs/mpage.c + :export: + +.. kernel-doc:: fs/namei.c + :export: + +.. kernel-doc:: fs/buffer.c + :export: + +.. kernel-doc:: block/bio.c + :export: + +.. kernel-doc:: fs/seq_file.c + :export: + +.. kernel-doc:: fs/filesystems.c + :export: + +.. kernel-doc:: fs/fs-writeback.c + :export: + +.. kernel-doc:: fs/block_dev.c + :export: + +The proc filesystem +=================== + +sysctl interface +---------------- + +.. kernel-doc:: kernel/sysctl.c + :export: + +proc filesystem interface +------------------------- + +.. kernel-doc:: fs/proc/base.c + :internal: + +Events based on file descriptors +================================ + +.. kernel-doc:: fs/eventfd.c + :export: + +The Filesystem for Exporting Kernel Objects +=========================================== + +.. kernel-doc:: fs/sysfs/file.c + :export: + +.. kernel-doc:: fs/sysfs/symlink.c + :export: + +The debugfs filesystem +====================== + +debugfs interface +----------------- + +.. kernel-doc:: fs/debugfs/inode.c + :export: + +.. kernel-doc:: fs/debugfs/file.c + :export: + +The Linux Journalling API +========================= + +Overview +-------- + +Details +~~~~~~~ + +The journalling layer is easy to use. You need to first of all create a +journal_t data structure. There are two calls to do this dependent on +how you decide to allocate the physical media on which the journal +resides. The :c:func:`jbd2_journal_init_inode` call is for journals stored in +filesystem inodes, or the :c:func:`jbd2_journal_init_dev` call can be used +for journal stored on a raw device (in a continuous range of blocks). A +journal_t is a typedef for a struct pointer, so when you are finally +finished make sure you call :c:func:`jbd2_journal_destroy` on it to free up +any used kernel memory. + +Once you have got your journal_t object you need to 'mount' or load the +journal file. The journalling layer expects the space for the journal +was already allocated and initialized properly by the userspace tools. +When loading the journal you must call :c:func:`jbd2_journal_load` to process +journal contents. If the client file system detects the journal contents +does not need to be processed (or even need not have valid contents), it +may call :c:func:`jbd2_journal_wipe` to clear the journal contents before +calling :c:func:`jbd2_journal_load`. + +Note that jbd2_journal_wipe(..,0) calls +:c:func:`jbd2_journal_skip_recovery` for you if it detects any outstanding +transactions in the journal and similarly :c:func:`jbd2_journal_load` will +call :c:func:`jbd2_journal_recover` if necessary. I would advise reading +:c:func:`ext4_load_journal` in fs/ext4/super.c for examples on this stage. + +Now you can go ahead and start modifying the underlying filesystem. +Almost. + +You still need to actually journal your filesystem changes, this is done +by wrapping them into transactions. Additionally you also need to wrap +the modification of each of the buffers with calls to the journal layer, +so it knows what the modifications you are actually making are. To do +this use :c:func:`jbd2_journal_start` which returns a transaction handle. + +:c:func:`jbd2_journal_start` and its counterpart :c:func:`jbd2_journal_stop`, +which indicates the end of a transaction are nestable calls, so you can +reenter a transaction if necessary, but remember you must call +:c:func:`jbd2_journal_stop` the same number of times as +:c:func:`jbd2_journal_start` before the transaction is completed (or more +accurately leaves the update phase). Ext4/VFS makes use of this feature to +simplify handling of inode dirtying, quota support, etc. + +Inside each transaction you need to wrap the modifications to the +individual buffers (blocks). Before you start to modify a buffer you +need to call :c:func:`jbd2_journal_get_create_access()` / +:c:func:`jbd2_journal_get_write_access()` / +:c:func:`jbd2_journal_get_undo_access()` as appropriate, this allows the +journalling layer to copy the unmodified +data if it needs to. After all the buffer may be part of a previously +uncommitted transaction. At this point you are at last ready to modify a +buffer, and once you are have done so you need to call +:c:func:`jbd2_journal_dirty_metadata`. Or if you've asked for access to a +buffer you now know is now longer required to be pushed back on the +device you can call :c:func:`jbd2_journal_forget` in much the same way as you +might have used :c:func:`bforget` in the past. + +A :c:func:`jbd2_journal_flush` may be called at any time to commit and +checkpoint all your transactions. + +Then at umount time , in your :c:func:`put_super` you can then call +:c:func:`jbd2_journal_destroy` to clean up your in-core journal object. + +Unfortunately there a couple of ways the journal layer can cause a +deadlock. The first thing to note is that each task can only have a +single outstanding transaction at any one time, remember nothing commits +until the outermost :c:func:`jbd2_journal_stop`. This means you must complete +the transaction at the end of each file/inode/address etc. operation you +perform, so that the journalling system isn't re-entered on another +journal. Since transactions can't be nested/batched across differing +journals, and another filesystem other than yours (say ext4) may be +modified in a later syscall. + +The second case to bear in mind is that :c:func:`jbd2_journal_start` can block +if there isn't enough space in the journal for your transaction (based +on the passed nblocks param) - when it blocks it merely(!) needs to wait +for transactions to complete and be committed from other tasks, so +essentially we are waiting for :c:func:`jbd2_journal_stop`. So to avoid +deadlocks you must treat :c:func:`jbd2_journal_start` / +:c:func:`jbd2_journal_stop` as if they were semaphores and include them in +your semaphore ordering rules to prevent +deadlocks. Note that :c:func:`jbd2_journal_extend` has similar blocking +behaviour to :c:func:`jbd2_journal_start` so you can deadlock here just as +easily as on :c:func:`jbd2_journal_start`. + +Try to reserve the right number of blocks the first time. ;-). This will +be the maximum number of blocks you are going to touch in this +transaction. I advise having a look at at least ext4_jbd.h to see the +basis on which ext4 uses to make these decisions. + +Another wriggle to watch out for is your on-disk block allocation +strategy. Why? Because, if you do a delete, you need to ensure you +haven't reused any of the freed blocks until the transaction freeing +these blocks commits. If you reused these blocks and crash happens, +there is no way to restore the contents of the reallocated blocks at the +end of the last fully committed transaction. One simple way of doing +this is to mark blocks as free in internal in-memory block allocation +structures only after the transaction freeing them commits. Ext4 uses +journal commit callback for this purpose. + +With journal commit callbacks you can ask the journalling layer to call +a callback function when the transaction is finally committed to disk, +so that you can do some of your own management. You ask the journalling +layer for calling the callback by simply setting +``journal->j_commit_callback`` function pointer and that function is +called after each transaction commit. You can also use +``transaction->t_private_list`` for attaching entries to a transaction +that need processing when the transaction commits. + +JBD2 also provides a way to block all transaction updates via +:c:func:`jbd2_journal_lock_updates()` / +:c:func:`jbd2_journal_unlock_updates()`. Ext4 uses this when it wants a +window with a clean and stable fs for a moment. E.g. + +:: + + + jbd2_journal_lock_updates() //stop new stuff happening.. + jbd2_journal_flush() // checkpoint everything. + ..do stuff on stable fs + jbd2_journal_unlock_updates() // carry on with filesystem use. + +The opportunities for abuse and DOS attacks with this should be obvious, +if you allow unprivileged userspace to trigger codepaths containing +these calls. + +Summary +~~~~~~~ + +Using the journal is a matter of wrapping the different context changes, +being each mount, each modification (transaction) and each changed +buffer to tell the journalling layer about them. + +Data Types +---------- + +The journalling layer uses typedefs to 'hide' the concrete definitions +of the structures used. As a client of the JBD2 layer you can just rely +on the using the pointer as a magic cookie of some sort. Obviously the +hiding is not enforced as this is 'C'. + +Structures +~~~~~~~~~~ + +.. kernel-doc:: include/linux/jbd2.h + :internal: + +Functions +--------- + +The functions here are split into two groups those that affect a journal +as a whole, and those which are used to manage transactions + +Journal Level +~~~~~~~~~~~~~ + +.. kernel-doc:: fs/jbd2/journal.c + :export: + +.. kernel-doc:: fs/jbd2/recovery.c + :internal: + +Transasction Level +~~~~~~~~~~~~~~~~~~ + +.. kernel-doc:: fs/jbd2/transaction.c + +See also +-------- + +`Journaling the Linux ext2fs Filesystem, LinuxExpo 98, Stephen +Tweedie <http://kernel.org/pub/linux/kernel/people/sct/ext3/journal-design.ps.gz>`__ + +`Ext3 Journalling FileSystem, OLS 2000, Dr. Stephen +Tweedie <http://olstrans.sourceforge.net/release/OLS2000-ext3/OLS2000-ext3.html>`__ + +splice API +========== + +splice is a method for moving blocks of data around inside the kernel, +without continually transferring them between the kernel and user space. + +.. kernel-doc:: fs/splice.c + +pipes API +========= + +Pipe interfaces are all for in-kernel (builtin image) use. They are not +exported for use by modules. + +.. kernel-doc:: include/linux/pipe_fs_i.h + :internal: + +.. kernel-doc:: fs/pipe.c diff --git a/Documentation/filesystems/nfs/idmapper.txt b/Documentation/filesystems/nfs/idmapper.txt index fe03d10bb79a..b86831acd583 100644 --- a/Documentation/filesystems/nfs/idmapper.txt +++ b/Documentation/filesystems/nfs/idmapper.txt @@ -55,7 +55,7 @@ request-key will find the first matching line and corresponding program. In this case, /some/other/program will handle all uid lookups and /usr/sbin/nfs.idmap will handle gid, user, and group lookups. -See <file:Documentation/security/keys-request-key.txt> for more information +See <file:Documentation/security/keys/request-key.rst> for more information about the request-key function. diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst index 1bdb7356a310..6162d0e9dc28 100644 --- a/Documentation/gpu/todo.rst +++ b/Documentation/gpu/todo.rst @@ -228,7 +228,7 @@ The DRM reference documentation is still lacking kerneldoc in a few areas. The task would be to clean up interfaces like moving functions around between files to better group them and improving the interfaces like dropping return values for functions that never fail. Then write kerneldoc for all exported -functions and an overview section and integrate it all into the drm DocBook. +functions and an overview section and integrate it all into the drm book. See https://dri.freedesktop.org/docs/drm/ for what's there already. diff --git a/Documentation/hwmon/ads1015 b/Documentation/hwmon/ads1015 index 063b80d857b1..02d2a459385f 100644 --- a/Documentation/hwmon/ads1015 +++ b/Documentation/hwmon/ads1015 @@ -40,7 +40,7 @@ By default all inputs are exported. Platform Data ------------- -In linux/i2c/ads1015.h platform data is defined, channel_data contains +In linux/platform_data/ads1015.h platform data is defined, channel_data contains configuration data for the used input combinations: - pga is the programmable gain amplifier (values are full scale) 0: +/- 6.144 V diff --git a/Documentation/hwmon/adt7475 b/Documentation/hwmon/adt7475 index 0502f2b464e1..09d73a10644c 100644 --- a/Documentation/hwmon/adt7475 +++ b/Documentation/hwmon/adt7475 @@ -109,6 +109,15 @@ fan speed) is applied. PWM values range from 0 (off) to 255 (full speed). Fan speed may be set to maximum when the temperature sensor associated with the PWM control exceeds temp#_max. +At Tmin - hysteresis the PWM output can either be off (0% duty cycle) or at the +minimum (i.e. auto_point1_pwm). This behaviour can be configured using the +pwm[1-*]_stall_disable sysfs attribute. A value of 0 means the fans will shut +off. A value of 1 means the fans will run at auto_point1_pwm. + +The responsiveness of the ADT747x to temperature changes can be configured. +This allows smoothing of the fan speed transition. To set the transition time +set the value in ms in the temp[1-*]_smoothing sysfs attribute. + Notes ----- diff --git a/Documentation/hwmon/ir35221 b/Documentation/hwmon/ir35221 new file mode 100644 index 000000000000..f7e112752c04 --- /dev/null +++ b/Documentation/hwmon/ir35221 @@ -0,0 +1,87 @@ +Kernel driver ir35221 +===================== + +Supported chips: + * Infinion IR35221 + Prefix: 'ir35221' + Addresses scanned: - + Datasheet: Datasheet is not publicly available. + +Author: Samuel Mendoza-Jonas <sam@mendozajonas.com> + + +Description +----------- + +IR35221 is a Digital DC-DC Multiphase Converter + + +Usage Notes +----------- + +This driver does not probe for PMBus devices. You will have to instantiate +devices explicitly. + +Example: the following commands will load the driver for an IR35221 +at address 0x70 on I2C bus #4: + +# modprobe ir35221 +# echo ir35221 0x70 > /sys/bus/i2c/devices/i2c-4/new_device + + +Sysfs attributes +---------------- + +curr1_label "iin" +curr1_input Measured input current +curr1_max Maximum current +curr1_max_alarm Current high alarm + +curr[2-3]_label "iout[1-2]" +curr[2-3]_input Measured output current +curr[2-3]_crit Critical maximum current +curr[2-3]_crit_alarm Current critical high alarm +curr[2-3]_highest Highest output current +curr[2-3]_lowest Lowest output current +curr[2-3]_max Maximum current +curr[2-3]_max_alarm Current high alarm + +in1_label "vin" +in1_input Measured input voltage +in1_crit Critical maximum input voltage +in1_crit_alarm Input voltage critical high alarm +in1_highest Highest input voltage +in1_lowest Lowest input voltage +in1_min Minimum input voltage +in1_min_alarm Input voltage low alarm + +in[2-3]_label "vout[1-2]" +in[2-3]_input Measured output voltage +in[2-3]_lcrit Critical minimum output voltage +in[2-3]_lcrit_alarm Output voltage critical low alarm +in[2-3]_crit Critical maximum output voltage +in[2-3]_crit_alarm Output voltage critical high alarm +in[2-3]_highest Highest output voltage +in[2-3]_lowest Lowest output voltage +in[2-3]_max Maximum output voltage +in[2-3]_max_alarm Output voltage high alarm +in[2-3]_min Minimum output voltage +in[2-3]_min_alarm Output voltage low alarm + +power1_label "pin" +power1_input Measured input power +power1_alarm Input power high alarm +power1_max Input power limit + +power[2-3]_label "pout[1-2]" +power[2-3]_input Measured output power +power[2-3]_max Output power limit +power[2-3]_max_alarm Output power high alarm + +temp[1-2]_input Measured temperature +temp[1-2]_crit Critical high temperature +temp[1-2]_crit_alarm Chip temperature critical high alarm +temp[1-2]_highest Highest temperature +temp[1-2]_lowest Lowest temperature +temp[1-2]_max Maximum temperature +temp[1-2]_max_alarm Chip temperature high alarm diff --git a/Documentation/hwmon/ltc4245 b/Documentation/hwmon/ltc4245 index b478b0864965..4ca7a9da09f9 100644 --- a/Documentation/hwmon/ltc4245 +++ b/Documentation/hwmon/ltc4245 @@ -96,7 +96,7 @@ slowly, -EAGAIN will be returned when you read the sysfs attribute containing the sensor reading. The LTC4245 chip can be configured to sample all GPIO pins with two methods: -1) platform data -- see include/linux/i2c/ltc4245.h +1) platform data -- see include/linux/platform_data/ltc4245.h 2) OF device tree -- add the "ltc4245,use-extra-gpios" property to each chip The default mode of operation is to sample a single GPIO pin. diff --git a/Documentation/hwmon/pmbus-core b/Documentation/hwmon/pmbus-core index 31e4720fed18..8ed10e9ddfb5 100644 --- a/Documentation/hwmon/pmbus-core +++ b/Documentation/hwmon/pmbus-core @@ -253,7 +253,7 @@ Specifically, it provides the following information. PMBus driver platform data ========================== -PMBus platform data is defined in include/linux/i2c/pmbus.h. Platform data +PMBus platform data is defined in include/linux/pmbus.h. Platform data currently only provides a flag field with a single bit used. #define PMBUS_SKIP_STATUS_CHECK (1 << 0) diff --git a/Documentation/index.rst b/Documentation/index.rst index bc67dbf76eb0..cb7f1ba5b3b1 100644 --- a/Documentation/index.rst +++ b/Documentation/index.rst @@ -3,8 +3,8 @@ You can adapt this file completely to your liking, but it should at least contain the root `toctree` directive. -Welcome to The Linux Kernel's documentation -=========================================== +The Linux Kernel documentation +============================== This is the top level of the kernel's documentation tree. Kernel documentation, like the kernel itself, is very much a work in progress; @@ -51,6 +51,7 @@ merged much easier. process/index dev-tools/index doc-guide/index + kernel-hacking/index Kernel API documentation ------------------------ @@ -67,11 +68,24 @@ needed). driver-api/index core-api/index media/index + networking/index input/index gpu/index security/index sound/index crypto/index + filesystems/index + +Architecture-specific documentation +----------------------------------- + +These books provide programming details about architecture-specific +implementation. + +.. toctree:: + :maxdepth: 2 + + sh/index Korean translations ------------------- diff --git a/Documentation/input/devices/edt-ft5x06.rst b/Documentation/input/devices/edt-ft5x06.rst index 2032f0b7a8fa..1ccc94b192b7 100644 --- a/Documentation/input/devices/edt-ft5x06.rst +++ b/Documentation/input/devices/edt-ft5x06.rst @@ -15,7 +15,7 @@ It has been tested with the following devices: The driver allows configuration of the touch screen via a set of sysfs files: /sys/class/input/eventX/device/device/threshold: - allows setting the "click"-threshold in the range from 20 to 80. + allows setting the "click"-threshold in the range from 0 to 80. /sys/class/input/eventX/device/device/gain: allows setting the sensitivity in the range from 0 to 31. Note that diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index e18daca65ccd..659afd56ecdb 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -1331,7 +1331,7 @@ See subsequent chapter for the syntax of the Kbuild file. --- 7.5 mandatory-y mandatory-y is essentially used by include/uapi/asm-generic/Kbuild.asm - to define the minimun set of headers that must be exported in + to define the minimum set of headers that must be exported in include/asm. The convention is to list one subdir per line and diff --git a/Documentation/kernel-doc-nano-HOWTO.txt b/Documentation/kernel-doc-nano-HOWTO.txt index 104740ea0041..c23e2c5ab80d 100644 --- a/Documentation/kernel-doc-nano-HOWTO.txt +++ b/Documentation/kernel-doc-nano-HOWTO.txt @@ -17,8 +17,8 @@ The format for this documentation is called the kernel-doc format. It is documented in this Documentation/kernel-doc-nano-HOWTO.txt file. This style embeds the documentation within the source files, using -a few simple conventions. The scripts/kernel-doc perl script, some -SGML templates in Documentation/DocBook, and other tools understand +a few simple conventions. The scripts/kernel-doc perl script, the +Documentation/sphinx/kerneldoc.py Sphinx extension and other tools understand these conventions, and are used to extract this embedded documentation into various documents. @@ -122,15 +122,9 @@ are: - scripts/kernel-doc This is a perl script that hunts for the block comments and can mark - them up directly into DocBook, man, text, and HTML. (No, not + them up directly into DocBook, ReST, man, text, and HTML. (No, not texinfo.) -- Documentation/DocBook/*.tmpl - - These are SGML template files, which are normal SGML files with - special place-holders for where the extracted documentation should - go. - - scripts/docproc.c This is a program for converting SGML template files into SGML @@ -145,25 +139,18 @@ are: - Makefile - The targets 'xmldocs', 'psdocs', 'pdfdocs', and 'htmldocs' are used - to build XML DocBook files, PostScript files, PDF files, and html files - in Documentation/DocBook. The older target 'sgmldocs' is equivalent - to 'xmldocs'. - -- Documentation/DocBook/Makefile - - This is where C files are associated with SGML templates. - + The targets 'xmldocs', 'latexdocs', 'pdfdocs', 'epubdocs'and 'htmldocs' + are used to build XML DocBook files, LaTeX files, PDF files, + ePub files and html files in Documentation/. How to extract the documentation -------------------------------- If you just want to read the ready-made books on the various -subsystems (see Documentation/DocBook/*.tmpl), just type 'make -psdocs', or 'make pdfdocs', or 'make htmldocs', depending on your -preference. If you would rather read a different format, you can type -'make xmldocs' and then use DocBook tools to convert -Documentation/DocBook/*.xml to a format of your choice (for example, +subsystems, just type 'make epubdocs', or 'make pdfdocs', or 'make htmldocs', +depending on your preference. If you would rather read a different format, +you can type 'make xmldocs' and then use DocBook tools to convert +Documentation/output/*.xml to a format of your choice (for example, 'db2html ...' if 'make htmldocs' was not defined). If you want to see man pages instead, you can do this: @@ -329,37 +316,7 @@ This is done by using a DOC: section keyword with a section title. E.g.: * hardware, software, or its subject(s). */ -DOC: sections are used in SGML templates files as indicated below. - - -How to make new SGML template files ------------------------------------ - -SGML template files (*.tmpl) are like normal SGML files, except that -they can contain escape sequences where extracted documentation should -be inserted. - -!E<filename> is replaced by the documentation, in <filename>, for -functions that are exported using EXPORT_SYMBOL: the function list is -collected from files listed in Documentation/DocBook/Makefile. - -!I<filename> is replaced by the documentation for functions that are -_not_ exported using EXPORT_SYMBOL. - -!D<filename> is used to name additional files to search for functions -exported using EXPORT_SYMBOL. - -!F<filename> <function [functions...]> is replaced by the -documentation, in <filename>, for the functions listed. - -!P<filename> <section title> is replaced by the contents of the DOC: -section titled <section title> from <filename>. -Spaces are allowed in <section title>; do not quote the <section title>. - -!C<filename> is replaced by nothing, but makes the tools check that -all DOC: sections and documented functions, symbols, etc. are used. -This makes sense to use when you use !F/!P only and want to verify -that all documentation is included. +DOC: sections are used in ReST files. Tim. */ <twaugh@redhat.com> diff --git a/Documentation/kernel-hacking/conf.py b/Documentation/kernel-hacking/conf.py new file mode 100644 index 000000000000..3d8acf0f33ad --- /dev/null +++ b/Documentation/kernel-hacking/conf.py @@ -0,0 +1,10 @@ +# -*- coding: utf-8; mode: python -*- + +project = "Kernel Hacking Guides" + +tags.add("subproject") + +latex_documents = [ + ('index', 'kernel-hacking.tex', project, + 'The kernel development community', 'manual'), +] diff --git a/Documentation/kernel-hacking/hacking.rst b/Documentation/kernel-hacking/hacking.rst new file mode 100644 index 000000000000..daf3883b2694 --- /dev/null +++ b/Documentation/kernel-hacking/hacking.rst @@ -0,0 +1,811 @@ +============================================ +Unreliable Guide To Hacking The Linux Kernel +============================================ + +:Author: Rusty Russell + +Introduction +============ + +Welcome, gentle reader, to Rusty's Remarkably Unreliable Guide to Linux +Kernel Hacking. This document describes the common routines and general +requirements for kernel code: its goal is to serve as a primer for Linux +kernel development for experienced C programmers. I avoid implementation +details: that's what the code is for, and I ignore whole tracts of +useful routines. + +Before you read this, please understand that I never wanted to write +this document, being grossly under-qualified, but I always wanted to +read it, and this was the only way. I hope it will grow into a +compendium of best practice, common starting points and random +information. + +The Players +=========== + +At any time each of the CPUs in a system can be: + +- not associated with any process, serving a hardware interrupt; + +- not associated with any process, serving a softirq or tasklet; + +- running in kernel space, associated with a process (user context); + +- running a process in user space. + +There is an ordering between these. The bottom two can preempt each +other, but above that is a strict hierarchy: each can only be preempted +by the ones above it. For example, while a softirq is running on a CPU, +no other softirq will preempt it, but a hardware interrupt can. However, +any other CPUs in the system execute independently. + +We'll see a number of ways that the user context can block interrupts, +to become truly non-preemptable. + +User Context +------------ + +User context is when you are coming in from a system call or other trap: +like userspace, you can be preempted by more important tasks and by +interrupts. You can sleep, by calling :c:func:`schedule()`. + +.. note:: + + You are always in user context on module load and unload, and on + operations on the block device layer. + +In user context, the ``current`` pointer (indicating the task we are +currently executing) is valid, and :c:func:`in_interrupt()` +(``include/linux/preempt.h``) is false. + +.. warning:: + + Beware that if you have preemption or softirqs disabled (see below), + :c:func:`in_interrupt()` will return a false positive. + +Hardware Interrupts (Hard IRQs) +------------------------------- + +Timer ticks, network cards and keyboard are examples of real hardware +which produce interrupts at any time. The kernel runs interrupt +handlers, which services the hardware. The kernel guarantees that this +handler is never re-entered: if the same interrupt arrives, it is queued +(or dropped). Because it disables interrupts, this handler has to be +fast: frequently it simply acknowledges the interrupt, marks a 'software +interrupt' for execution and exits. + +You can tell you are in a hardware interrupt, because +:c:func:`in_irq()` returns true. + +.. warning:: + + Beware that this will return a false positive if interrupts are + disabled (see below). + +Software Interrupt Context: Softirqs and Tasklets +------------------------------------------------- + +Whenever a system call is about to return to userspace, or a hardware +interrupt handler exits, any 'software interrupts' which are marked +pending (usually by hardware interrupts) are run (``kernel/softirq.c``). + +Much of the real interrupt handling work is done here. Early in the +transition to SMP, there were only 'bottom halves' (BHs), which didn't +take advantage of multiple CPUs. Shortly after we switched from wind-up +computers made of match-sticks and snot, we abandoned this limitation +and switched to 'softirqs'. + +``include/linux/interrupt.h`` lists the different softirqs. A very +important softirq is the timer softirq (``include/linux/timer.h``): you +can register to have it call functions for you in a given length of +time. + +Softirqs are often a pain to deal with, since the same softirq will run +simultaneously on more than one CPU. For this reason, tasklets +(``include/linux/interrupt.h``) are more often used: they are +dynamically-registrable (meaning you can have as many as you want), and +they also guarantee that any tasklet will only run on one CPU at any +time, although different tasklets can run simultaneously. + +.. warning:: + + The name 'tasklet' is misleading: they have nothing to do with + 'tasks', and probably more to do with some bad vodka Alexey + Kuznetsov had at the time. + +You can tell you are in a softirq (or tasklet) using the +:c:func:`in_softirq()` macro (``include/linux/preempt.h``). + +.. warning:: + + Beware that this will return a false positive if a + :ref:`botton half lock <local_bh_disable>` is held. + +Some Basic Rules +================ + +No memory protection + If you corrupt memory, whether in user context or interrupt context, + the whole machine will crash. Are you sure you can't do what you + want in userspace? + +No floating point or MMX + The FPU context is not saved; even in user context the FPU state + probably won't correspond with the current process: you would mess + with some user process' FPU state. If you really want to do this, + you would have to explicitly save/restore the full FPU state (and + avoid context switches). It is generally a bad idea; use fixed point + arithmetic first. + +A rigid stack limit + Depending on configuration options the kernel stack is about 3K to + 6K for most 32-bit architectures: it's about 14K on most 64-bit + archs, and often shared with interrupts so you can't use it all. + Avoid deep recursion and huge local arrays on the stack (allocate + them dynamically instead). + +The Linux kernel is portable + Let's keep it that way. Your code should be 64-bit clean, and + endian-independent. You should also minimize CPU specific stuff, + e.g. inline assembly should be cleanly encapsulated and minimized to + ease porting. Generally it should be restricted to the + architecture-dependent part of the kernel tree. + +ioctls: Not writing a new system call +===================================== + +A system call generally looks like this:: + + asmlinkage long sys_mycall(int arg) + { + return 0; + } + + +First, in most cases you don't want to create a new system call. You +create a character device and implement an appropriate ioctl for it. +This is much more flexible than system calls, doesn't have to be entered +in every architecture's ``include/asm/unistd.h`` and +``arch/kernel/entry.S`` file, and is much more likely to be accepted by +Linus. + +If all your routine does is read or write some parameter, consider +implementing a :c:func:`sysfs()` interface instead. + +Inside the ioctl you're in user context to a process. When a error +occurs you return a negated errno (see +``include/uapi/asm-generic/errno-base.h``, +``include/uapi/asm-generic/errno.h`` and ``include/linux/errno.h``), +otherwise you return 0. + +After you slept you should check if a signal occurred: the Unix/Linux +way of handling signals is to temporarily exit the system call with the +``-ERESTARTSYS`` error. The system call entry code will switch back to +user context, process the signal handler and then your system call will +be restarted (unless the user disabled that). So you should be prepared +to process the restart, e.g. if you're in the middle of manipulating +some data structure. + +:: + + if (signal_pending(current)) + return -ERESTARTSYS; + + +If you're doing longer computations: first think userspace. If you +**really** want to do it in kernel you should regularly check if you need +to give up the CPU (remember there is cooperative multitasking per CPU). +Idiom:: + + cond_resched(); /* Will sleep */ + + +A short note on interface design: the UNIX system call motto is "Provide +mechanism not policy". + +Recipes for Deadlock +==================== + +You cannot call any routines which may sleep, unless: + +- You are in user context. + +- You do not own any spinlocks. + +- You have interrupts enabled (actually, Andi Kleen says that the + scheduling code will enable them for you, but that's probably not + what you wanted). + +Note that some functions may sleep implicitly: common ones are the user +space access functions (\*_user) and memory allocation functions +without ``GFP_ATOMIC``. + +You should always compile your kernel ``CONFIG_DEBUG_ATOMIC_SLEEP`` on, +and it will warn you if you break these rules. If you **do** break the +rules, you will eventually lock up your box. + +Really. + +Common Routines +=============== + +:c:func:`printk()` +------------------ + +Defined in ``include/linux/printk.h`` + +:c:func:`printk()` feeds kernel messages to the console, dmesg, and +the syslog daemon. It is useful for debugging and reporting errors, and +can be used inside interrupt context, but use with caution: a machine +which has its console flooded with printk messages is unusable. It uses +a format string mostly compatible with ANSI C printf, and C string +concatenation to give it a first "priority" argument:: + + printk(KERN_INFO "i = %u\n", i); + + +See ``include/linux/kern_levels.h``; for other ``KERN_`` values; these are +interpreted by syslog as the level. Special case: for printing an IP +address use:: + + __be32 ipaddress; + printk(KERN_INFO "my ip: %pI4\n", &ipaddress); + + +:c:func:`printk()` internally uses a 1K buffer and does not catch +overruns. Make sure that will be enough. + +.. note:: + + You will know when you are a real kernel hacker when you start + typoing printf as printk in your user programs :) + +.. note:: + + Another sidenote: the original Unix Version 6 sources had a comment + on top of its printf function: "Printf should not be used for + chit-chat". You should follow that advice. + +:c:func:`copy_to_user()` / :c:func:`copy_from_user()` / :c:func:`get_user()` / :c:func:`put_user()` +--------------------------------------------------------------------------------------------------- + +Defined in ``include/linux/uaccess.h`` / ``asm/uaccess.h`` + +**[SLEEPS]** + +:c:func:`put_user()` and :c:func:`get_user()` are used to get +and put single values (such as an int, char, or long) from and to +userspace. A pointer into userspace should never be simply dereferenced: +data should be copied using these routines. Both return ``-EFAULT`` or +0. + +:c:func:`copy_to_user()` and :c:func:`copy_from_user()` are +more general: they copy an arbitrary amount of data to and from +userspace. + +.. warning:: + + Unlike :c:func:`put_user()` and :c:func:`get_user()`, they + return the amount of uncopied data (ie. 0 still means success). + +[Yes, this moronic interface makes me cringe. The flamewar comes up +every year or so. --RR.] + +The functions may sleep implicitly. This should never be called outside +user context (it makes no sense), with interrupts disabled, or a +spinlock held. + +:c:func:`kmalloc()`/:c:func:`kfree()` +------------------------------------- + +Defined in ``include/linux/slab.h`` + +**[MAY SLEEP: SEE BELOW]** + +These routines are used to dynamically request pointer-aligned chunks of +memory, like malloc and free do in userspace, but +:c:func:`kmalloc()` takes an extra flag word. Important values: + +``GFP_KERNEL`` + May sleep and swap to free memory. Only allowed in user context, but + is the most reliable way to allocate memory. + +``GFP_ATOMIC`` + Don't sleep. Less reliable than ``GFP_KERNEL``, but may be called + from interrupt context. You should **really** have a good + out-of-memory error-handling strategy. + +``GFP_DMA`` + Allocate ISA DMA lower than 16MB. If you don't know what that is you + don't need it. Very unreliable. + +If you see a sleeping function called from invalid context warning +message, then maybe you called a sleeping allocation function from +interrupt context without ``GFP_ATOMIC``. You should really fix that. +Run, don't walk. + +If you are allocating at least ``PAGE_SIZE`` (``asm/page.h`` or +``asm/page_types.h``) bytes, consider using :c:func:`__get_free_pages()` +(``include/linux/gfp.h``). It takes an order argument (0 for page sized, +1 for double page, 2 for four pages etc.) and the same memory priority +flag word as above. + +If you are allocating more than a page worth of bytes you can use +:c:func:`vmalloc()`. It'll allocate virtual memory in the kernel +map. This block is not contiguous in physical memory, but the MMU makes +it look like it is for you (so it'll only look contiguous to the CPUs, +not to external device drivers). If you really need large physically +contiguous memory for some weird device, you have a problem: it is +poorly supported in Linux because after some time memory fragmentation +in a running kernel makes it hard. The best way is to allocate the block +early in the boot process via the :c:func:`alloc_bootmem()` +routine. + +Before inventing your own cache of often-used objects consider using a +slab cache in ``include/linux/slab.h`` + +:c:func:`current()` +------------------- + +Defined in ``include/asm/current.h`` + +This global variable (really a macro) contains a pointer to the current +task structure, so is only valid in user context. For example, when a +process makes a system call, this will point to the task structure of +the calling process. It is **not NULL** in interrupt context. + +:c:func:`mdelay()`/:c:func:`udelay()` +------------------------------------- + +Defined in ``include/asm/delay.h`` / ``include/linux/delay.h`` + +The :c:func:`udelay()` and :c:func:`ndelay()` functions can be +used for small pauses. Do not use large values with them as you risk +overflow - the helper function :c:func:`mdelay()` is useful here, or +consider :c:func:`msleep()`. + +:c:func:`cpu_to_be32()`/:c:func:`be32_to_cpu()`/:c:func:`cpu_to_le32()`/:c:func:`le32_to_cpu()` +----------------------------------------------------------------------------------------------- + +Defined in ``include/asm/byteorder.h`` + +The :c:func:`cpu_to_be32()` family (where the "32" can be replaced +by 64 or 16, and the "be" can be replaced by "le") are the general way +to do endian conversions in the kernel: they return the converted value. +All variations supply the reverse as well: +:c:func:`be32_to_cpu()`, etc. + +There are two major variations of these functions: the pointer +variation, such as :c:func:`cpu_to_be32p()`, which take a pointer +to the given type, and return the converted value. The other variation +is the "in-situ" family, such as :c:func:`cpu_to_be32s()`, which +convert value referred to by the pointer, and return void. + +:c:func:`local_irq_save()`/:c:func:`local_irq_restore()` +-------------------------------------------------------- + +Defined in ``include/linux/irqflags.h`` + +These routines disable hard interrupts on the local CPU, and restore +them. They are reentrant; saving the previous state in their one +``unsigned long flags`` argument. If you know that interrupts are +enabled, you can simply use :c:func:`local_irq_disable()` and +:c:func:`local_irq_enable()`. + +.. _local_bh_disable: + +:c:func:`local_bh_disable()`/:c:func:`local_bh_enable()` +-------------------------------------------------------- + +Defined in ``include/linux/bottom_half.h`` + + +These routines disable soft interrupts on the local CPU, and restore +them. They are reentrant; if soft interrupts were disabled before, they +will still be disabled after this pair of functions has been called. +They prevent softirqs and tasklets from running on the current CPU. + +:c:func:`smp_processor_id()` +---------------------------- + +Defined in ``include/linux/smp.h`` + +:c:func:`get_cpu()` disables preemption (so you won't suddenly get +moved to another CPU) and returns the current processor number, between +0 and ``NR_CPUS``. Note that the CPU numbers are not necessarily +continuous. You return it again with :c:func:`put_cpu()` when you +are done. + +If you know you cannot be preempted by another task (ie. you are in +interrupt context, or have preemption disabled) you can use +smp_processor_id(). + +``__init``/``__exit``/``__initdata`` +------------------------------------ + +Defined in ``include/linux/init.h`` + +After boot, the kernel frees up a special section; functions marked with +``__init`` and data structures marked with ``__initdata`` are dropped +after boot is complete: similarly modules discard this memory after +initialization. ``__exit`` is used to declare a function which is only +required on exit: the function will be dropped if this file is not +compiled as a module. See the header file for use. Note that it makes no +sense for a function marked with ``__init`` to be exported to modules +with :c:func:`EXPORT_SYMBOL()` or :c:func:`EXPORT_SYMBOL_GPL()`- this +will break. + +:c:func:`__initcall()`/:c:func:`module_init()` +---------------------------------------------- + +Defined in ``include/linux/init.h`` / ``include/linux/module.h`` + +Many parts of the kernel are well served as a module +(dynamically-loadable parts of the kernel). Using the +:c:func:`module_init()` and :c:func:`module_exit()` macros it +is easy to write code without #ifdefs which can operate both as a module +or built into the kernel. + +The :c:func:`module_init()` macro defines which function is to be +called at module insertion time (if the file is compiled as a module), +or at boot time: if the file is not compiled as a module the +:c:func:`module_init()` macro becomes equivalent to +:c:func:`__initcall()`, which through linker magic ensures that +the function is called on boot. + +The function can return a negative error number to cause module loading +to fail (unfortunately, this has no effect if the module is compiled +into the kernel). This function is called in user context with +interrupts enabled, so it can sleep. + +:c:func:`module_exit()` +----------------------- + + +Defined in ``include/linux/module.h`` + +This macro defines the function to be called at module removal time (or +never, in the case of the file compiled into the kernel). It will only +be called if the module usage count has reached zero. This function can +also sleep, but cannot fail: everything must be cleaned up by the time +it returns. + +Note that this macro is optional: if it is not present, your module will +not be removable (except for 'rmmod -f'). + +:c:func:`try_module_get()`/:c:func:`module_put()` +------------------------------------------------- + +Defined in ``include/linux/module.h`` + +These manipulate the module usage count, to protect against removal (a +module also can't be removed if another module uses one of its exported +symbols: see below). Before calling into module code, you should call +:c:func:`try_module_get()` on that module: if it fails, then the +module is being removed and you should act as if it wasn't there. +Otherwise, you can safely enter the module, and call +:c:func:`module_put()` when you're finished. + +Most registerable structures have an owner field, such as in the +:c:type:`struct file_operations <file_operations>` structure. +Set this field to the macro ``THIS_MODULE``. + +Wait Queues ``include/linux/wait.h`` +==================================== + +**[SLEEPS]** + +A wait queue is used to wait for someone to wake you up when a certain +condition is true. They must be used carefully to ensure there is no +race condition. You declare a :c:type:`wait_queue_head_t`, and then processes +which want to wait for that condition declare a :c:type:`wait_queue_entry_t` +referring to themselves, and place that in the queue. + +Declaring +--------- + +You declare a ``wait_queue_head_t`` using the +:c:func:`DECLARE_WAIT_QUEUE_HEAD()` macro, or using the +:c:func:`init_waitqueue_head()` routine in your initialization +code. + +Queuing +------- + +Placing yourself in the waitqueue is fairly complex, because you must +put yourself in the queue before checking the condition. There is a +macro to do this: :c:func:`wait_event_interruptible()` +(``include/linux/wait.h``) The first argument is the wait queue head, and +the second is an expression which is evaluated; the macro returns 0 when +this expression is true, or ``-ERESTARTSYS`` if a signal is received. The +:c:func:`wait_event()` version ignores signals. + +Waking Up Queued Tasks +---------------------- + +Call :c:func:`wake_up()` (``include/linux/wait.h``);, which will wake +up every process in the queue. The exception is if one has +``TASK_EXCLUSIVE`` set, in which case the remainder of the queue will +not be woken. There are other variants of this basic function available +in the same header. + +Atomic Operations +================= + +Certain operations are guaranteed atomic on all platforms. The first +class of operations work on :c:type:`atomic_t` (``include/asm/atomic.h``); +this contains a signed integer (at least 32 bits long), and you must use +these functions to manipulate or read :c:type:`atomic_t` variables. +:c:func:`atomic_read()` and :c:func:`atomic_set()` get and set +the counter, :c:func:`atomic_add()`, :c:func:`atomic_sub()`, +:c:func:`atomic_inc()`, :c:func:`atomic_dec()`, and +:c:func:`atomic_dec_and_test()` (returns true if it was +decremented to zero). + +Yes. It returns true (i.e. != 0) if the atomic variable is zero. + +Note that these functions are slower than normal arithmetic, and so +should not be used unnecessarily. + +The second class of atomic operations is atomic bit operations on an +``unsigned long``, defined in ``include/linux/bitops.h``. These +operations generally take a pointer to the bit pattern, and a bit +number: 0 is the least significant bit. :c:func:`set_bit()`, +:c:func:`clear_bit()` and :c:func:`change_bit()` set, clear, +and flip the given bit. :c:func:`test_and_set_bit()`, +:c:func:`test_and_clear_bit()` and +:c:func:`test_and_change_bit()` do the same thing, except return +true if the bit was previously set; these are particularly useful for +atomically setting flags. + +It is possible to call these operations with bit indices greater than +``BITS_PER_LONG``. The resulting behavior is strange on big-endian +platforms though so it is a good idea not to do this. + +Symbols +======= + +Within the kernel proper, the normal linking rules apply (ie. unless a +symbol is declared to be file scope with the ``static`` keyword, it can +be used anywhere in the kernel). However, for modules, a special +exported symbol table is kept which limits the entry points to the +kernel proper. Modules can also export symbols. + +:c:func:`EXPORT_SYMBOL()` +------------------------- + +Defined in ``include/linux/export.h`` + +This is the classic method of exporting a symbol: dynamically loaded +modules will be able to use the symbol as normal. + +:c:func:`EXPORT_SYMBOL_GPL()` +----------------------------- + +Defined in ``include/linux/export.h`` + +Similar to :c:func:`EXPORT_SYMBOL()` except that the symbols +exported by :c:func:`EXPORT_SYMBOL_GPL()` can only be seen by +modules with a :c:func:`MODULE_LICENSE()` that specifies a GPL +compatible license. It implies that the function is considered an +internal implementation issue, and not really an interface. Some +maintainers and developers may however require EXPORT_SYMBOL_GPL() +when adding any new APIs or functionality. + +Routines and Conventions +======================== + +Double-linked lists ``include/linux/list.h`` +-------------------------------------------- + +There used to be three sets of linked-list routines in the kernel +headers, but this one is the winner. If you don't have some particular +pressing need for a single list, it's a good choice. + +In particular, :c:func:`list_for_each_entry()` is useful. + +Return Conventions +------------------ + +For code called in user context, it's very common to defy C convention, +and return 0 for success, and a negative error number (eg. ``-EFAULT``) for +failure. This can be unintuitive at first, but it's fairly widespread in +the kernel. + +Using :c:func:`ERR_PTR()` (``include/linux/err.h``) to encode a +negative error number into a pointer, and :c:func:`IS_ERR()` and +:c:func:`PTR_ERR()` to get it back out again: avoids a separate +pointer parameter for the error number. Icky, but in a good way. + +Breaking Compilation +-------------------- + +Linus and the other developers sometimes change function or structure +names in development kernels; this is not done just to keep everyone on +their toes: it reflects a fundamental change (eg. can no longer be +called with interrupts on, or does extra checks, or doesn't do checks +which were caught before). Usually this is accompanied by a fairly +complete note to the linux-kernel mailing list; search the archive. +Simply doing a global replace on the file usually makes things **worse**. + +Initializing structure members +------------------------------ + +The preferred method of initializing structures is to use designated +initialisers, as defined by ISO C99, eg:: + + static struct block_device_operations opt_fops = { + .open = opt_open, + .release = opt_release, + .ioctl = opt_ioctl, + .check_media_change = opt_media_change, + }; + + +This makes it easy to grep for, and makes it clear which structure +fields are set. You should do this because it looks cool. + +GNU Extensions +-------------- + +GNU Extensions are explicitly allowed in the Linux kernel. Note that +some of the more complex ones are not very well supported, due to lack +of general use, but the following are considered standard (see the GCC +info page section "C Extensions" for more details - Yes, really the info +page, the man page is only a short summary of the stuff in info). + +- Inline functions + +- Statement expressions (ie. the ({ and }) constructs). + +- Declaring attributes of a function / variable / type + (__attribute__) + +- typeof + +- Zero length arrays + +- Macro varargs + +- Arithmetic on void pointers + +- Non-Constant initializers + +- Assembler Instructions (not outside arch/ and include/asm/) + +- Function names as strings (__func__). + +- __builtin_constant_p() + +Be wary when using long long in the kernel, the code gcc generates for +it is horrible and worse: division and multiplication does not work on +i386 because the GCC runtime functions for it are missing from the +kernel environment. + +C++ +--- + +Using C++ in the kernel is usually a bad idea, because the kernel does +not provide the necessary runtime environment and the include files are +not tested for it. It is still possible, but not recommended. If you +really want to do this, forget about exceptions at least. + +NUMif +----- + +It is generally considered cleaner to use macros in header files (or at +the top of .c files) to abstract away functions rather than using \`#if' +pre-processor statements throughout the source code. + +Putting Your Stuff in the Kernel +================================ + +In order to get your stuff into shape for official inclusion, or even to +make a neat patch, there's administrative work to be done: + +- Figure out whose pond you've been pissing in. Look at the top of the + source files, inside the ``MAINTAINERS`` file, and last of all in the + ``CREDITS`` file. You should coordinate with this person to make sure + you're not duplicating effort, or trying something that's already + been rejected. + + Make sure you put your name and EMail address at the top of any files + you create or mangle significantly. This is the first place people + will look when they find a bug, or when **they** want to make a change. + +- Usually you want a configuration option for your kernel hack. Edit + ``Kconfig`` in the appropriate directory. The Config language is + simple to use by cut and paste, and there's complete documentation in + ``Documentation/kbuild/kconfig-language.txt``. + + In your description of the option, make sure you address both the + expert user and the user who knows nothing about your feature. + Mention incompatibilities and issues here. **Definitely** end your + description with “if in doubt, say N” (or, occasionally, \`Y'); this + is for people who have no idea what you are talking about. + +- Edit the ``Makefile``: the CONFIG variables are exported here so you + can usually just add a "obj-$(CONFIG_xxx) += xxx.o" line. The syntax + is documented in ``Documentation/kbuild/makefiles.txt``. + +- Put yourself in ``CREDITS`` if you've done something noteworthy, + usually beyond a single file (your name should be at the top of the + source files anyway). ``MAINTAINERS`` means you want to be consulted + when changes are made to a subsystem, and hear about bugs; it implies + a more-than-passing commitment to some part of the code. + +- Finally, don't forget to read + ``Documentation/process/submitting-patches.rst`` and possibly + ``Documentation/process/submitting-drivers.rst``. + +Kernel Cantrips +=============== + +Some favorites from browsing the source. Feel free to add to this list. + +``arch/x86/include/asm/delay.h``:: + + #define ndelay(n) (__builtin_constant_p(n) ? \ + ((n) > 20000 ? __bad_ndelay() : __const_udelay((n) * 5ul)) : \ + __ndelay(n)) + + +``include/linux/fs.h``:: + + /* + * Kernel pointers have redundant information, so we can use a + * scheme where we can return either an error code or a dentry + * pointer with the same return value. + * + * This should be a per-architecture thing, to allow different + * error and pointer decisions. + */ + #define ERR_PTR(err) ((void *)((long)(err))) + #define PTR_ERR(ptr) ((long)(ptr)) + #define IS_ERR(ptr) ((unsigned long)(ptr) > (unsigned long)(-1000)) + +``arch/x86/include/asm/uaccess_32.h:``:: + + #define copy_to_user(to,from,n) \ + (__builtin_constant_p(n) ? \ + __constant_copy_to_user((to),(from),(n)) : \ + __generic_copy_to_user((to),(from),(n))) + + +``arch/sparc/kernel/head.S:``:: + + /* + * Sun people can't spell worth damn. "compatability" indeed. + * At least we *know* we can't spell, and use a spell-checker. + */ + + /* Uh, actually Linus it is I who cannot spell. Too much murky + * Sparc assembly will do this to ya. + */ + C_LABEL(cputypvar): + .asciz "compatibility" + + /* Tested on SS-5, SS-10. Probably someone at Sun applied a spell-checker. */ + .align 4 + C_LABEL(cputypvar_sun4m): + .asciz "compatible" + + +``arch/sparc/lib/checksum.S:``:: + + /* Sun, you just can't beat me, you just can't. Stop trying, + * give up. I'm serious, I am going to kick the living shit + * out of you, game over, lights out. + */ + + +Thanks +====== + +Thanks to Andi Kleen for the idea, answering my questions, fixing my +mistakes, filling content, etc. Philipp Rumpf for more spelling and +clarity fixes, and some excellent non-obvious points. Werner Almesberger +for giving me a great summary of :c:func:`disable_irq()`, and Jes +Sorensen and Andrea Arcangeli added caveats. Michael Elizabeth Chastain +for checking and adding to the Configure section. Telsa Gwynne for +teaching me DocBook. diff --git a/Documentation/kernel-hacking/index.rst b/Documentation/kernel-hacking/index.rst new file mode 100644 index 000000000000..fcb0eda3cca3 --- /dev/null +++ b/Documentation/kernel-hacking/index.rst @@ -0,0 +1,9 @@ +===================== +Kernel Hacking Guides +===================== + +.. toctree:: + :maxdepth: 2 + + hacking + locking diff --git a/Documentation/kernel-hacking/locking.rst b/Documentation/kernel-hacking/locking.rst new file mode 100644 index 000000000000..f937c0fd11aa --- /dev/null +++ b/Documentation/kernel-hacking/locking.rst @@ -0,0 +1,1446 @@ +=========================== +Unreliable Guide To Locking +=========================== + +:Author: Rusty Russell + +Introduction +============ + +Welcome, to Rusty's Remarkably Unreliable Guide to Kernel Locking +issues. This document describes the locking systems in the Linux Kernel +in 2.6. + +With the wide availability of HyperThreading, and preemption in the +Linux Kernel, everyone hacking on the kernel needs to know the +fundamentals of concurrency and locking for SMP. + +The Problem With Concurrency +============================ + +(Skip this if you know what a Race Condition is). + +In a normal program, you can increment a counter like so: + +:: + + very_important_count++; + + +This is what they would expect to happen: + + +.. table:: Expected Results + + +------------------------------------+------------------------------------+ + | Instance 1 | Instance 2 | + +====================================+====================================+ + | read very_important_count (5) | | + +------------------------------------+------------------------------------+ + | add 1 (6) | | + +------------------------------------+------------------------------------+ + | write very_important_count (6) | | + +------------------------------------+------------------------------------+ + | | read very_important_count (6) | + +------------------------------------+------------------------------------+ + | | add 1 (7) | + +------------------------------------+------------------------------------+ + | | write very_important_count (7) | + +------------------------------------+------------------------------------+ + +This is what might happen: + +.. table:: Possible Results + + +------------------------------------+------------------------------------+ + | Instance 1 | Instance 2 | + +====================================+====================================+ + | read very_important_count (5) | | + +------------------------------------+------------------------------------+ + | | read very_important_count (5) | + +------------------------------------+------------------------------------+ + | add 1 (6) | | + +------------------------------------+------------------------------------+ + | | add 1 (6) | + +------------------------------------+------------------------------------+ + | write very_important_count (6) | | + +------------------------------------+------------------------------------+ + | | write very_important_count (6) | + +------------------------------------+------------------------------------+ + + +Race Conditions and Critical Regions +------------------------------------ + +This overlap, where the result depends on the relative timing of +multiple tasks, is called a race condition. The piece of code containing +the concurrency issue is called a critical region. And especially since +Linux starting running on SMP machines, they became one of the major +issues in kernel design and implementation. + +Preemption can have the same effect, even if there is only one CPU: by +preempting one task during the critical region, we have exactly the same +race condition. In this case the thread which preempts might run the +critical region itself. + +The solution is to recognize when these simultaneous accesses occur, and +use locks to make sure that only one instance can enter the critical +region at any time. There are many friendly primitives in the Linux +kernel to help you do this. And then there are the unfriendly +primitives, but I'll pretend they don't exist. + +Locking in the Linux Kernel +=========================== + +If I could give you one piece of advice: never sleep with anyone crazier +than yourself. But if I had to give you advice on locking: **keep it +simple**. + +Be reluctant to introduce new locks. + +Strangely enough, this last one is the exact reverse of my advice when +you **have** slept with someone crazier than yourself. And you should +think about getting a big dog. + +Two Main Types of Kernel Locks: Spinlocks and Mutexes +----------------------------------------------------- + +There are two main types of kernel locks. The fundamental type is the +spinlock (``include/asm/spinlock.h``), which is a very simple +single-holder lock: if you can't get the spinlock, you keep trying +(spinning) until you can. Spinlocks are very small and fast, and can be +used anywhere. + +The second type is a mutex (``include/linux/mutex.h``): it is like a +spinlock, but you may block holding a mutex. If you can't lock a mutex, +your task will suspend itself, and be woken up when the mutex is +released. This means the CPU can do something else while you are +waiting. There are many cases when you simply can't sleep (see +`What Functions Are Safe To Call From Interrupts? <#sleeping-things>`__), +and so have to use a spinlock instead. + +Neither type of lock is recursive: see +`Deadlock: Simple and Advanced <#deadlock>`__. + +Locks and Uniprocessor Kernels +------------------------------ + +For kernels compiled without ``CONFIG_SMP``, and without +``CONFIG_PREEMPT`` spinlocks do not exist at all. This is an excellent +design decision: when no-one else can run at the same time, there is no +reason to have a lock. + +If the kernel is compiled without ``CONFIG_SMP``, but ``CONFIG_PREEMPT`` +is set, then spinlocks simply disable preemption, which is sufficient to +prevent any races. For most purposes, we can think of preemption as +equivalent to SMP, and not worry about it separately. + +You should always test your locking code with ``CONFIG_SMP`` and +``CONFIG_PREEMPT`` enabled, even if you don't have an SMP test box, +because it will still catch some kinds of locking bugs. + +Mutexes still exist, because they are required for synchronization +between user contexts, as we will see below. + +Locking Only In User Context +---------------------------- + +If you have a data structure which is only ever accessed from user +context, then you can use a simple mutex (``include/linux/mutex.h``) to +protect it. This is the most trivial case: you initialize the mutex. +Then you can call :c:func:`mutex_lock_interruptible()` to grab the +mutex, and :c:func:`mutex_unlock()` to release it. There is also a +:c:func:`mutex_lock()`, which should be avoided, because it will +not return if a signal is received. + +Example: ``net/netfilter/nf_sockopt.c`` allows registration of new +:c:func:`setsockopt()` and :c:func:`getsockopt()` calls, with +:c:func:`nf_register_sockopt()`. Registration and de-registration +are only done on module load and unload (and boot time, where there is +no concurrency), and the list of registrations is only consulted for an +unknown :c:func:`setsockopt()` or :c:func:`getsockopt()` system +call. The ``nf_sockopt_mutex`` is perfect to protect this, especially +since the setsockopt and getsockopt calls may well sleep. + +Locking Between User Context and Softirqs +----------------------------------------- + +If a softirq shares data with user context, you have two problems. +Firstly, the current user context can be interrupted by a softirq, and +secondly, the critical region could be entered from another CPU. This is +where :c:func:`spin_lock_bh()` (``include/linux/spinlock.h``) is +used. It disables softirqs on that CPU, then grabs the lock. +:c:func:`spin_unlock_bh()` does the reverse. (The '_bh' suffix is +a historical reference to "Bottom Halves", the old name for software +interrupts. It should really be called spin_lock_softirq()' in a +perfect world). + +Note that you can also use :c:func:`spin_lock_irq()` or +:c:func:`spin_lock_irqsave()` here, which stop hardware interrupts +as well: see `Hard IRQ Context <#hardirq-context>`__. + +This works perfectly for UP as well: the spin lock vanishes, and this +macro simply becomes :c:func:`local_bh_disable()` +(``include/linux/interrupt.h``), which protects you from the softirq +being run. + +Locking Between User Context and Tasklets +----------------------------------------- + +This is exactly the same as above, because tasklets are actually run +from a softirq. + +Locking Between User Context and Timers +--------------------------------------- + +This, too, is exactly the same as above, because timers are actually run +from a softirq. From a locking point of view, tasklets and timers are +identical. + +Locking Between Tasklets/Timers +------------------------------- + +Sometimes a tasklet or timer might want to share data with another +tasklet or timer. + +The Same Tasklet/Timer +~~~~~~~~~~~~~~~~~~~~~~ + +Since a tasklet is never run on two CPUs at once, you don't need to +worry about your tasklet being reentrant (running twice at once), even +on SMP. + +Different Tasklets/Timers +~~~~~~~~~~~~~~~~~~~~~~~~~ + +If another tasklet/timer wants to share data with your tasklet or timer +, you will both need to use :c:func:`spin_lock()` and +:c:func:`spin_unlock()` calls. :c:func:`spin_lock_bh()` is +unnecessary here, as you are already in a tasklet, and none will be run +on the same CPU. + +Locking Between Softirqs +------------------------ + +Often a softirq might want to share data with itself or a tasklet/timer. + +The Same Softirq +~~~~~~~~~~~~~~~~ + +The same softirq can run on the other CPUs: you can use a per-CPU array +(see `Per-CPU Data <#per-cpu>`__) for better performance. If you're +going so far as to use a softirq, you probably care about scalable +performance enough to justify the extra complexity. + +You'll need to use :c:func:`spin_lock()` and +:c:func:`spin_unlock()` for shared data. + +Different Softirqs +~~~~~~~~~~~~~~~~~~ + +You'll need to use :c:func:`spin_lock()` and +:c:func:`spin_unlock()` for shared data, whether it be a timer, +tasklet, different softirq or the same or another softirq: any of them +could be running on a different CPU. + +Hard IRQ Context +================ + +Hardware interrupts usually communicate with a tasklet or softirq. +Frequently this involves putting work in a queue, which the softirq will +take out. + +Locking Between Hard IRQ and Softirqs/Tasklets +---------------------------------------------- + +If a hardware irq handler shares data with a softirq, you have two +concerns. Firstly, the softirq processing can be interrupted by a +hardware interrupt, and secondly, the critical region could be entered +by a hardware interrupt on another CPU. This is where +:c:func:`spin_lock_irq()` is used. It is defined to disable +interrupts on that cpu, then grab the lock. +:c:func:`spin_unlock_irq()` does the reverse. + +The irq handler does not to use :c:func:`spin_lock_irq()`, because +the softirq cannot run while the irq handler is running: it can use +:c:func:`spin_lock()`, which is slightly faster. The only exception +would be if a different hardware irq handler uses the same lock: +:c:func:`spin_lock_irq()` will stop that from interrupting us. + +This works perfectly for UP as well: the spin lock vanishes, and this +macro simply becomes :c:func:`local_irq_disable()` +(``include/asm/smp.h``), which protects you from the softirq/tasklet/BH +being run. + +:c:func:`spin_lock_irqsave()` (``include/linux/spinlock.h``) is a +variant which saves whether interrupts were on or off in a flags word, +which is passed to :c:func:`spin_unlock_irqrestore()`. This means +that the same code can be used inside an hard irq handler (where +interrupts are already off) and in softirqs (where the irq disabling is +required). + +Note that softirqs (and hence tasklets and timers) are run on return +from hardware interrupts, so :c:func:`spin_lock_irq()` also stops +these. In that sense, :c:func:`spin_lock_irqsave()` is the most +general and powerful locking function. + +Locking Between Two Hard IRQ Handlers +------------------------------------- + +It is rare to have to share data between two IRQ handlers, but if you +do, :c:func:`spin_lock_irqsave()` should be used: it is +architecture-specific whether all interrupts are disabled inside irq +handlers themselves. + +Cheat Sheet For Locking +======================= + +Pete Zaitcev gives the following summary: + +- If you are in a process context (any syscall) and want to lock other + process out, use a mutex. You can take a mutex and sleep + (``copy_from_user*(`` or ``kmalloc(x,GFP_KERNEL)``). + +- Otherwise (== data can be touched in an interrupt), use + :c:func:`spin_lock_irqsave()` and + :c:func:`spin_unlock_irqrestore()`. + +- Avoid holding spinlock for more than 5 lines of code and across any + function call (except accessors like :c:func:`readb()`). + +Table of Minimum Requirements +----------------------------- + +The following table lists the **minimum** locking requirements between +various contexts. In some cases, the same context can only be running on +one CPU at a time, so no locking is required for that context (eg. a +particular thread can only run on one CPU at a time, but if it needs +shares data with another thread, locking is required). + +Remember the advice above: you can always use +:c:func:`spin_lock_irqsave()`, which is a superset of all other +spinlock primitives. + +============== ============= ============= ========= ========= ========= ========= ======= ======= ============== ============== +. IRQ Handler A IRQ Handler B Softirq A Softirq B Tasklet A Tasklet B Timer A Timer B User Context A User Context B +============== ============= ============= ========= ========= ========= ========= ======= ======= ============== ============== +IRQ Handler A None +IRQ Handler B SLIS None +Softirq A SLI SLI SL +Softirq B SLI SLI SL SL +Tasklet A SLI SLI SL SL None +Tasklet B SLI SLI SL SL SL None +Timer A SLI SLI SL SL SL SL None +Timer B SLI SLI SL SL SL SL SL None +User Context A SLI SLI SLBH SLBH SLBH SLBH SLBH SLBH None +User Context B SLI SLI SLBH SLBH SLBH SLBH SLBH SLBH MLI None +============== ============= ============= ========= ========= ========= ========= ======= ======= ============== ============== + +Table: Table of Locking Requirements + ++--------+----------------------------+ +| SLIS | spin_lock_irqsave | ++--------+----------------------------+ +| SLI | spin_lock_irq | ++--------+----------------------------+ +| SL | spin_lock | ++--------+----------------------------+ +| SLBH | spin_lock_bh | ++--------+----------------------------+ +| MLI | mutex_lock_interruptible | ++--------+----------------------------+ + +Table: Legend for Locking Requirements Table + +The trylock Functions +===================== + +There are functions that try to acquire a lock only once and immediately +return a value telling about success or failure to acquire the lock. +They can be used if you need no access to the data protected with the +lock when some other thread is holding the lock. You should acquire the +lock later if you then need access to the data protected with the lock. + +:c:func:`spin_trylock()` does not spin but returns non-zero if it +acquires the spinlock on the first try or 0 if not. This function can be +used in all contexts like :c:func:`spin_lock()`: you must have +disabled the contexts that might interrupt you and acquire the spin +lock. + +:c:func:`mutex_trylock()` does not suspend your task but returns +non-zero if it could lock the mutex on the first try or 0 if not. This +function cannot be safely used in hardware or software interrupt +contexts despite not sleeping. + +Common Examples +=============== + +Let's step through a simple example: a cache of number to name mappings. +The cache keeps a count of how often each of the objects is used, and +when it gets full, throws out the least used one. + +All In User Context +------------------- + +For our first example, we assume that all operations are in user context +(ie. from system calls), so we can sleep. This means we can use a mutex +to protect the cache and all the objects within it. Here's the code:: + + #include <linux/list.h> + #include <linux/slab.h> + #include <linux/string.h> + #include <linux/mutex.h> + #include <asm/errno.h> + + struct object + { + struct list_head list; + int id; + char name[32]; + int popularity; + }; + + /* Protects the cache, cache_num, and the objects within it */ + static DEFINE_MUTEX(cache_lock); + static LIST_HEAD(cache); + static unsigned int cache_num = 0; + #define MAX_CACHE_SIZE 10 + + /* Must be holding cache_lock */ + static struct object *__cache_find(int id) + { + struct object *i; + + list_for_each_entry(i, &cache, list) + if (i->id == id) { + i->popularity++; + return i; + } + return NULL; + } + + /* Must be holding cache_lock */ + static void __cache_delete(struct object *obj) + { + BUG_ON(!obj); + list_del(&obj->list); + kfree(obj); + cache_num--; + } + + /* Must be holding cache_lock */ + static void __cache_add(struct object *obj) + { + list_add(&obj->list, &cache); + if (++cache_num > MAX_CACHE_SIZE) { + struct object *i, *outcast = NULL; + list_for_each_entry(i, &cache, list) { + if (!outcast || i->popularity < outcast->popularity) + outcast = i; + } + __cache_delete(outcast); + } + } + + int cache_add(int id, const char *name) + { + struct object *obj; + + if ((obj = kmalloc(sizeof(*obj), GFP_KERNEL)) == NULL) + return -ENOMEM; + + strlcpy(obj->name, name, sizeof(obj->name)); + obj->id = id; + obj->popularity = 0; + + mutex_lock(&cache_lock); + __cache_add(obj); + mutex_unlock(&cache_lock); + return 0; + } + + void cache_delete(int id) + { + mutex_lock(&cache_lock); + __cache_delete(__cache_find(id)); + mutex_unlock(&cache_lock); + } + + int cache_find(int id, char *name) + { + struct object *obj; + int ret = -ENOENT; + + mutex_lock(&cache_lock); + obj = __cache_find(id); + if (obj) { + ret = 0; + strcpy(name, obj->name); + } + mutex_unlock(&cache_lock); + return ret; + } + +Note that we always make sure we have the cache_lock when we add, +delete, or look up the cache: both the cache infrastructure itself and +the contents of the objects are protected by the lock. In this case it's +easy, since we copy the data for the user, and never let them access the +objects directly. + +There is a slight (and common) optimization here: in +:c:func:`cache_add()` we set up the fields of the object before +grabbing the lock. This is safe, as no-one else can access it until we +put it in cache. + +Accessing From Interrupt Context +-------------------------------- + +Now consider the case where :c:func:`cache_find()` can be called +from interrupt context: either a hardware interrupt or a softirq. An +example would be a timer which deletes object from the cache. + +The change is shown below, in standard patch format: the ``-`` are lines +which are taken away, and the ``+`` are lines which are added. + +:: + + --- cache.c.usercontext 2003-12-09 13:58:54.000000000 +1100 + +++ cache.c.interrupt 2003-12-09 14:07:49.000000000 +1100 + @@ -12,7 +12,7 @@ + int popularity; + }; + + -static DEFINE_MUTEX(cache_lock); + +static DEFINE_SPINLOCK(cache_lock); + static LIST_HEAD(cache); + static unsigned int cache_num = 0; + #define MAX_CACHE_SIZE 10 + @@ -55,6 +55,7 @@ + int cache_add(int id, const char *name) + { + struct object *obj; + + unsigned long flags; + + if ((obj = kmalloc(sizeof(*obj), GFP_KERNEL)) == NULL) + return -ENOMEM; + @@ -63,30 +64,33 @@ + obj->id = id; + obj->popularity = 0; + + - mutex_lock(&cache_lock); + + spin_lock_irqsave(&cache_lock, flags); + __cache_add(obj); + - mutex_unlock(&cache_lock); + + spin_unlock_irqrestore(&cache_lock, flags); + return 0; + } + + void cache_delete(int id) + { + - mutex_lock(&cache_lock); + + unsigned long flags; + + + + spin_lock_irqsave(&cache_lock, flags); + __cache_delete(__cache_find(id)); + - mutex_unlock(&cache_lock); + + spin_unlock_irqrestore(&cache_lock, flags); + } + + int cache_find(int id, char *name) + { + struct object *obj; + int ret = -ENOENT; + + unsigned long flags; + + - mutex_lock(&cache_lock); + + spin_lock_irqsave(&cache_lock, flags); + obj = __cache_find(id); + if (obj) { + ret = 0; + strcpy(name, obj->name); + } + - mutex_unlock(&cache_lock); + + spin_unlock_irqrestore(&cache_lock, flags); + return ret; + } + +Note that the :c:func:`spin_lock_irqsave()` will turn off +interrupts if they are on, otherwise does nothing (if we are already in +an interrupt handler), hence these functions are safe to call from any +context. + +Unfortunately, :c:func:`cache_add()` calls :c:func:`kmalloc()` +with the ``GFP_KERNEL`` flag, which is only legal in user context. I +have assumed that :c:func:`cache_add()` is still only called in +user context, otherwise this should become a parameter to +:c:func:`cache_add()`. + +Exposing Objects Outside This File +---------------------------------- + +If our objects contained more information, it might not be sufficient to +copy the information in and out: other parts of the code might want to +keep pointers to these objects, for example, rather than looking up the +id every time. This produces two problems. + +The first problem is that we use the ``cache_lock`` to protect objects: +we'd need to make this non-static so the rest of the code can use it. +This makes locking trickier, as it is no longer all in one place. + +The second problem is the lifetime problem: if another structure keeps a +pointer to an object, it presumably expects that pointer to remain +valid. Unfortunately, this is only guaranteed while you hold the lock, +otherwise someone might call :c:func:`cache_delete()` and even +worse, add another object, re-using the same address. + +As there is only one lock, you can't hold it forever: no-one else would +get any work done. + +The solution to this problem is to use a reference count: everyone who +has a pointer to the object increases it when they first get the object, +and drops the reference count when they're finished with it. Whoever +drops it to zero knows it is unused, and can actually delete it. + +Here is the code:: + + --- cache.c.interrupt 2003-12-09 14:25:43.000000000 +1100 + +++ cache.c.refcnt 2003-12-09 14:33:05.000000000 +1100 + @@ -7,6 +7,7 @@ + struct object + { + struct list_head list; + + unsigned int refcnt; + int id; + char name[32]; + int popularity; + @@ -17,6 +18,35 @@ + static unsigned int cache_num = 0; + #define MAX_CACHE_SIZE 10 + + +static void __object_put(struct object *obj) + +{ + + if (--obj->refcnt == 0) + + kfree(obj); + +} + + + +static void __object_get(struct object *obj) + +{ + + obj->refcnt++; + +} + + + +void object_put(struct object *obj) + +{ + + unsigned long flags; + + + + spin_lock_irqsave(&cache_lock, flags); + + __object_put(obj); + + spin_unlock_irqrestore(&cache_lock, flags); + +} + + + +void object_get(struct object *obj) + +{ + + unsigned long flags; + + + + spin_lock_irqsave(&cache_lock, flags); + + __object_get(obj); + + spin_unlock_irqrestore(&cache_lock, flags); + +} + + + /* Must be holding cache_lock */ + static struct object *__cache_find(int id) + { + @@ -35,6 +65,7 @@ + { + BUG_ON(!obj); + list_del(&obj->list); + + __object_put(obj); + cache_num--; + } + + @@ -63,6 +94,7 @@ + strlcpy(obj->name, name, sizeof(obj->name)); + obj->id = id; + obj->popularity = 0; + + obj->refcnt = 1; /* The cache holds a reference */ + + spin_lock_irqsave(&cache_lock, flags); + __cache_add(obj); + @@ -79,18 +111,15 @@ + spin_unlock_irqrestore(&cache_lock, flags); + } + + -int cache_find(int id, char *name) + +struct object *cache_find(int id) + { + struct object *obj; + - int ret = -ENOENT; + unsigned long flags; + + spin_lock_irqsave(&cache_lock, flags); + obj = __cache_find(id); + - if (obj) { + - ret = 0; + - strcpy(name, obj->name); + - } + + if (obj) + + __object_get(obj); + spin_unlock_irqrestore(&cache_lock, flags); + - return ret; + + return obj; + } + +We encapsulate the reference counting in the standard 'get' and 'put' +functions. Now we can return the object itself from +:c:func:`cache_find()` which has the advantage that the user can +now sleep holding the object (eg. to :c:func:`copy_to_user()` to +name to userspace). + +The other point to note is that I said a reference should be held for +every pointer to the object: thus the reference count is 1 when first +inserted into the cache. In some versions the framework does not hold a +reference count, but they are more complicated. + +Using Atomic Operations For The Reference Count +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +In practice, :c:type:`atomic_t` would usually be used for refcnt. There are a +number of atomic operations defined in ``include/asm/atomic.h``: these +are guaranteed to be seen atomically from all CPUs in the system, so no +lock is required. In this case, it is simpler than using spinlocks, +although for anything non-trivial using spinlocks is clearer. The +:c:func:`atomic_inc()` and :c:func:`atomic_dec_and_test()` +are used instead of the standard increment and decrement operators, and +the lock is no longer used to protect the reference count itself. + +:: + + --- cache.c.refcnt 2003-12-09 15:00:35.000000000 +1100 + +++ cache.c.refcnt-atomic 2003-12-11 15:49:42.000000000 +1100 + @@ -7,7 +7,7 @@ + struct object + { + struct list_head list; + - unsigned int refcnt; + + atomic_t refcnt; + int id; + char name[32]; + int popularity; + @@ -18,33 +18,15 @@ + static unsigned int cache_num = 0; + #define MAX_CACHE_SIZE 10 + + -static void __object_put(struct object *obj) + -{ + - if (--obj->refcnt == 0) + - kfree(obj); + -} + - + -static void __object_get(struct object *obj) + -{ + - obj->refcnt++; + -} + - + void object_put(struct object *obj) + { + - unsigned long flags; + - + - spin_lock_irqsave(&cache_lock, flags); + - __object_put(obj); + - spin_unlock_irqrestore(&cache_lock, flags); + + if (atomic_dec_and_test(&obj->refcnt)) + + kfree(obj); + } + + void object_get(struct object *obj) + { + - unsigned long flags; + - + - spin_lock_irqsave(&cache_lock, flags); + - __object_get(obj); + - spin_unlock_irqrestore(&cache_lock, flags); + + atomic_inc(&obj->refcnt); + } + + /* Must be holding cache_lock */ + @@ -65,7 +47,7 @@ + { + BUG_ON(!obj); + list_del(&obj->list); + - __object_put(obj); + + object_put(obj); + cache_num--; + } + + @@ -94,7 +76,7 @@ + strlcpy(obj->name, name, sizeof(obj->name)); + obj->id = id; + obj->popularity = 0; + - obj->refcnt = 1; /* The cache holds a reference */ + + atomic_set(&obj->refcnt, 1); /* The cache holds a reference */ + + spin_lock_irqsave(&cache_lock, flags); + __cache_add(obj); + @@ -119,7 +101,7 @@ + spin_lock_irqsave(&cache_lock, flags); + obj = __cache_find(id); + if (obj) + - __object_get(obj); + + object_get(obj); + spin_unlock_irqrestore(&cache_lock, flags); + return obj; + } + +Protecting The Objects Themselves +--------------------------------- + +In these examples, we assumed that the objects (except the reference +counts) never changed once they are created. If we wanted to allow the +name to change, there are three possibilities: + +- You can make ``cache_lock`` non-static, and tell people to grab that + lock before changing the name in any object. + +- You can provide a :c:func:`cache_obj_rename()` which grabs this + lock and changes the name for the caller, and tell everyone to use + that function. + +- You can make the ``cache_lock`` protect only the cache itself, and + use another lock to protect the name. + +Theoretically, you can make the locks as fine-grained as one lock for +every field, for every object. In practice, the most common variants +are: + +- One lock which protects the infrastructure (the ``cache`` list in + this example) and all the objects. This is what we have done so far. + +- One lock which protects the infrastructure (including the list + pointers inside the objects), and one lock inside the object which + protects the rest of that object. + +- Multiple locks to protect the infrastructure (eg. one lock per hash + chain), possibly with a separate per-object lock. + +Here is the "lock-per-object" implementation: + +:: + + --- cache.c.refcnt-atomic 2003-12-11 15:50:54.000000000 +1100 + +++ cache.c.perobjectlock 2003-12-11 17:15:03.000000000 +1100 + @@ -6,11 +6,17 @@ + + struct object + { + + /* These two protected by cache_lock. */ + struct list_head list; + + int popularity; + + + atomic_t refcnt; + + + + /* Doesn't change once created. */ + int id; + + + + spinlock_t lock; /* Protects the name */ + char name[32]; + - int popularity; + }; + + static DEFINE_SPINLOCK(cache_lock); + @@ -77,6 +84,7 @@ + obj->id = id; + obj->popularity = 0; + atomic_set(&obj->refcnt, 1); /* The cache holds a reference */ + + spin_lock_init(&obj->lock); + + spin_lock_irqsave(&cache_lock, flags); + __cache_add(obj); + +Note that I decide that the popularity count should be protected by the +``cache_lock`` rather than the per-object lock: this is because it (like +the :c:type:`struct list_head <list_head>` inside the object) +is logically part of the infrastructure. This way, I don't need to grab +the lock of every object in :c:func:`__cache_add()` when seeking +the least popular. + +I also decided that the id member is unchangeable, so I don't need to +grab each object lock in :c:func:`__cache_find()` to examine the +id: the object lock is only used by a caller who wants to read or write +the name field. + +Note also that I added a comment describing what data was protected by +which locks. This is extremely important, as it describes the runtime +behavior of the code, and can be hard to gain from just reading. And as +Alan Cox says, “Lock data, not code”. + +Common Problems +=============== + +Deadlock: Simple and Advanced +----------------------------- + +There is a coding bug where a piece of code tries to grab a spinlock +twice: it will spin forever, waiting for the lock to be released +(spinlocks, rwlocks and mutexes are not recursive in Linux). This is +trivial to diagnose: not a +stay-up-five-nights-talk-to-fluffy-code-bunnies kind of problem. + +For a slightly more complex case, imagine you have a region shared by a +softirq and user context. If you use a :c:func:`spin_lock()` call +to protect it, it is possible that the user context will be interrupted +by the softirq while it holds the lock, and the softirq will then spin +forever trying to get the same lock. + +Both of these are called deadlock, and as shown above, it can occur even +with a single CPU (although not on UP compiles, since spinlocks vanish +on kernel compiles with ``CONFIG_SMP``\ =n. You'll still get data +corruption in the second example). + +This complete lockup is easy to diagnose: on SMP boxes the watchdog +timer or compiling with ``DEBUG_SPINLOCK`` set +(``include/linux/spinlock.h``) will show this up immediately when it +happens. + +A more complex problem is the so-called 'deadly embrace', involving two +or more locks. Say you have a hash table: each entry in the table is a +spinlock, and a chain of hashed objects. Inside a softirq handler, you +sometimes want to alter an object from one place in the hash to another: +you grab the spinlock of the old hash chain and the spinlock of the new +hash chain, and delete the object from the old one, and insert it in the +new one. + +There are two problems here. First, if your code ever tries to move the +object to the same chain, it will deadlock with itself as it tries to +lock it twice. Secondly, if the same softirq on another CPU is trying to +move another object in the reverse direction, the following could +happen: + ++-----------------------+-----------------------+ +| CPU 1 | CPU 2 | ++=======================+=======================+ +| Grab lock A -> OK | Grab lock B -> OK | ++-----------------------+-----------------------+ +| Grab lock B -> spin | Grab lock A -> spin | ++-----------------------+-----------------------+ + +Table: Consequences + +The two CPUs will spin forever, waiting for the other to give up their +lock. It will look, smell, and feel like a crash. + +Preventing Deadlock +------------------- + +Textbooks will tell you that if you always lock in the same order, you +will never get this kind of deadlock. Practice will tell you that this +approach doesn't scale: when I create a new lock, I don't understand +enough of the kernel to figure out where in the 5000 lock hierarchy it +will fit. + +The best locks are encapsulated: they never get exposed in headers, and +are never held around calls to non-trivial functions outside the same +file. You can read through this code and see that it will never +deadlock, because it never tries to grab another lock while it has that +one. People using your code don't even need to know you are using a +lock. + +A classic problem here is when you provide callbacks or hooks: if you +call these with the lock held, you risk simple deadlock, or a deadly +embrace (who knows what the callback will do?). Remember, the other +programmers are out to get you, so don't do this. + +Overzealous Prevention Of Deadlocks +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Deadlocks are problematic, but not as bad as data corruption. Code which +grabs a read lock, searches a list, fails to find what it wants, drops +the read lock, grabs a write lock and inserts the object has a race +condition. + +If you don't see why, please stay the fuck away from my code. + +Racing Timers: A Kernel Pastime +------------------------------- + +Timers can produce their own special problems with races. Consider a +collection of objects (list, hash, etc) where each object has a timer +which is due to destroy it. + +If you want to destroy the entire collection (say on module removal), +you might do the following:: + + /* THIS CODE BAD BAD BAD BAD: IF IT WAS ANY WORSE IT WOULD USE + HUNGARIAN NOTATION */ + spin_lock_bh(&list_lock); + + while (list) { + struct foo *next = list->next; + del_timer(&list->timer); + kfree(list); + list = next; + } + + spin_unlock_bh(&list_lock); + + +Sooner or later, this will crash on SMP, because a timer can have just +gone off before the :c:func:`spin_lock_bh()`, and it will only get +the lock after we :c:func:`spin_unlock_bh()`, and then try to free +the element (which has already been freed!). + +This can be avoided by checking the result of +:c:func:`del_timer()`: if it returns 1, the timer has been deleted. +If 0, it means (in this case) that it is currently running, so we can +do:: + + retry: + spin_lock_bh(&list_lock); + + while (list) { + struct foo *next = list->next; + if (!del_timer(&list->timer)) { + /* Give timer a chance to delete this */ + spin_unlock_bh(&list_lock); + goto retry; + } + kfree(list); + list = next; + } + + spin_unlock_bh(&list_lock); + + +Another common problem is deleting timers which restart themselves (by +calling :c:func:`add_timer()` at the end of their timer function). +Because this is a fairly common case which is prone to races, you should +use :c:func:`del_timer_sync()` (``include/linux/timer.h``) to +handle this case. It returns the number of times the timer had to be +deleted before we finally stopped it from adding itself back in. + +Locking Speed +============= + +There are three main things to worry about when considering speed of +some code which does locking. First is concurrency: how many things are +going to be waiting while someone else is holding a lock. Second is the +time taken to actually acquire and release an uncontended lock. Third is +using fewer, or smarter locks. I'm assuming that the lock is used fairly +often: otherwise, you wouldn't be concerned about efficiency. + +Concurrency depends on how long the lock is usually held: you should +hold the lock for as long as needed, but no longer. In the cache +example, we always create the object without the lock held, and then +grab the lock only when we are ready to insert it in the list. + +Acquisition times depend on how much damage the lock operations do to +the pipeline (pipeline stalls) and how likely it is that this CPU was +the last one to grab the lock (ie. is the lock cache-hot for this CPU): +on a machine with more CPUs, this likelihood drops fast. Consider a +700MHz Intel Pentium III: an instruction takes about 0.7ns, an atomic +increment takes about 58ns, a lock which is cache-hot on this CPU takes +160ns, and a cacheline transfer from another CPU takes an additional 170 +to 360ns. (These figures from Paul McKenney's `Linux Journal RCU +article <http://www.linuxjournal.com/article.php?sid=6993>`__). + +These two aims conflict: holding a lock for a short time might be done +by splitting locks into parts (such as in our final per-object-lock +example), but this increases the number of lock acquisitions, and the +results are often slower than having a single lock. This is another +reason to advocate locking simplicity. + +The third concern is addressed below: there are some methods to reduce +the amount of locking which needs to be done. + +Read/Write Lock Variants +------------------------ + +Both spinlocks and mutexes have read/write variants: ``rwlock_t`` and +:c:type:`struct rw_semaphore <rw_semaphore>`. These divide +users into two classes: the readers and the writers. If you are only +reading the data, you can get a read lock, but to write to the data you +need the write lock. Many people can hold a read lock, but a writer must +be sole holder. + +If your code divides neatly along reader/writer lines (as our cache code +does), and the lock is held by readers for significant lengths of time, +using these locks can help. They are slightly slower than the normal +locks though, so in practice ``rwlock_t`` is not usually worthwhile. + +Avoiding Locks: Read Copy Update +-------------------------------- + +There is a special method of read/write locking called Read Copy Update. +Using RCU, the readers can avoid taking a lock altogether: as we expect +our cache to be read more often than updated (otherwise the cache is a +waste of time), it is a candidate for this optimization. + +How do we get rid of read locks? Getting rid of read locks means that +writers may be changing the list underneath the readers. That is +actually quite simple: we can read a linked list while an element is +being added if the writer adds the element very carefully. For example, +adding ``new`` to a single linked list called ``list``:: + + new->next = list->next; + wmb(); + list->next = new; + + +The :c:func:`wmb()` is a write memory barrier. It ensures that the +first operation (setting the new element's ``next`` pointer) is complete +and will be seen by all CPUs, before the second operation is (putting +the new element into the list). This is important, since modern +compilers and modern CPUs can both reorder instructions unless told +otherwise: we want a reader to either not see the new element at all, or +see the new element with the ``next`` pointer correctly pointing at the +rest of the list. + +Fortunately, there is a function to do this for standard +:c:type:`struct list_head <list_head>` lists: +:c:func:`list_add_rcu()` (``include/linux/list.h``). + +Removing an element from the list is even simpler: we replace the +pointer to the old element with a pointer to its successor, and readers +will either see it, or skip over it. + +:: + + list->next = old->next; + + +There is :c:func:`list_del_rcu()` (``include/linux/list.h``) which +does this (the normal version poisons the old object, which we don't +want). + +The reader must also be careful: some CPUs can look through the ``next`` +pointer to start reading the contents of the next element early, but +don't realize that the pre-fetched contents is wrong when the ``next`` +pointer changes underneath them. Once again, there is a +:c:func:`list_for_each_entry_rcu()` (``include/linux/list.h``) +to help you. Of course, writers can just use +:c:func:`list_for_each_entry()`, since there cannot be two +simultaneous writers. + +Our final dilemma is this: when can we actually destroy the removed +element? Remember, a reader might be stepping through this element in +the list right now: if we free this element and the ``next`` pointer +changes, the reader will jump off into garbage and crash. We need to +wait until we know that all the readers who were traversing the list +when we deleted the element are finished. We use +:c:func:`call_rcu()` to register a callback which will actually +destroy the object once all pre-existing readers are finished. +Alternatively, :c:func:`synchronize_rcu()` may be used to block +until all pre-existing are finished. + +But how does Read Copy Update know when the readers are finished? The +method is this: firstly, the readers always traverse the list inside +:c:func:`rcu_read_lock()`/:c:func:`rcu_read_unlock()` pairs: +these simply disable preemption so the reader won't go to sleep while +reading the list. + +RCU then waits until every other CPU has slept at least once: since +readers cannot sleep, we know that any readers which were traversing the +list during the deletion are finished, and the callback is triggered. +The real Read Copy Update code is a little more optimized than this, but +this is the fundamental idea. + +:: + + --- cache.c.perobjectlock 2003-12-11 17:15:03.000000000 +1100 + +++ cache.c.rcupdate 2003-12-11 17:55:14.000000000 +1100 + @@ -1,15 +1,18 @@ + #include <linux/list.h> + #include <linux/slab.h> + #include <linux/string.h> + +#include <linux/rcupdate.h> + #include <linux/mutex.h> + #include <asm/errno.h> + + struct object + { + - /* These two protected by cache_lock. */ + + /* This is protected by RCU */ + struct list_head list; + int popularity; + + + struct rcu_head rcu; + + + atomic_t refcnt; + + /* Doesn't change once created. */ + @@ -40,7 +43,7 @@ + { + struct object *i; + + - list_for_each_entry(i, &cache, list) { + + list_for_each_entry_rcu(i, &cache, list) { + if (i->id == id) { + i->popularity++; + return i; + @@ -49,19 +52,25 @@ + return NULL; + } + + +/* Final discard done once we know no readers are looking. */ + +static void cache_delete_rcu(void *arg) + +{ + + object_put(arg); + +} + + + /* Must be holding cache_lock */ + static void __cache_delete(struct object *obj) + { + BUG_ON(!obj); + - list_del(&obj->list); + - object_put(obj); + + list_del_rcu(&obj->list); + cache_num--; + + call_rcu(&obj->rcu, cache_delete_rcu); + } + + /* Must be holding cache_lock */ + static void __cache_add(struct object *obj) + { + - list_add(&obj->list, &cache); + + list_add_rcu(&obj->list, &cache); + if (++cache_num > MAX_CACHE_SIZE) { + struct object *i, *outcast = NULL; + list_for_each_entry(i, &cache, list) { + @@ -104,12 +114,11 @@ + struct object *cache_find(int id) + { + struct object *obj; + - unsigned long flags; + + - spin_lock_irqsave(&cache_lock, flags); + + rcu_read_lock(); + obj = __cache_find(id); + if (obj) + object_get(obj); + - spin_unlock_irqrestore(&cache_lock, flags); + + rcu_read_unlock(); + return obj; + } + +Note that the reader will alter the popularity member in +:c:func:`__cache_find()`, and now it doesn't hold a lock. One +solution would be to make it an ``atomic_t``, but for this usage, we +don't really care about races: an approximate result is good enough, so +I didn't change it. + +The result is that :c:func:`cache_find()` requires no +synchronization with any other functions, so is almost as fast on SMP as +it would be on UP. + +There is a further optimization possible here: remember our original +cache code, where there were no reference counts and the caller simply +held the lock whenever using the object? This is still possible: if you +hold the lock, no one can delete the object, so you don't need to get +and put the reference count. + +Now, because the 'read lock' in RCU is simply disabling preemption, a +caller which always has preemption disabled between calling +:c:func:`cache_find()` and :c:func:`object_put()` does not +need to actually get and put the reference count: we could expose +:c:func:`__cache_find()` by making it non-static, and such +callers could simply call that. + +The benefit here is that the reference count is not written to: the +object is not altered in any way, which is much faster on SMP machines +due to caching. + +Per-CPU Data +------------ + +Another technique for avoiding locking which is used fairly widely is to +duplicate information for each CPU. For example, if you wanted to keep a +count of a common condition, you could use a spin lock and a single +counter. Nice and simple. + +If that was too slow (it's usually not, but if you've got a really big +machine to test on and can show that it is), you could instead use a +counter for each CPU, then none of them need an exclusive lock. See +:c:func:`DEFINE_PER_CPU()`, :c:func:`get_cpu_var()` and +:c:func:`put_cpu_var()` (``include/linux/percpu.h``). + +Of particular use for simple per-cpu counters is the ``local_t`` type, +and the :c:func:`cpu_local_inc()` and related functions, which are +more efficient than simple code on some architectures +(``include/asm/local.h``). + +Note that there is no simple, reliable way of getting an exact value of +such a counter, without introducing more locks. This is not a problem +for some uses. + +Data Which Mostly Used By An IRQ Handler +---------------------------------------- + +If data is always accessed from within the same IRQ handler, you don't +need a lock at all: the kernel already guarantees that the irq handler +will not run simultaneously on multiple CPUs. + +Manfred Spraul points out that you can still do this, even if the data +is very occasionally accessed in user context or softirqs/tasklets. The +irq handler doesn't use a lock, and all other accesses are done as so:: + + spin_lock(&lock); + disable_irq(irq); + ... + enable_irq(irq); + spin_unlock(&lock); + +The :c:func:`disable_irq()` prevents the irq handler from running +(and waits for it to finish if it's currently running on other CPUs). +The spinlock prevents any other accesses happening at the same time. +Naturally, this is slower than just a :c:func:`spin_lock_irq()` +call, so it only makes sense if this type of access happens extremely +rarely. + +What Functions Are Safe To Call From Interrupts? +================================================ + +Many functions in the kernel sleep (ie. call schedule()) directly or +indirectly: you can never call them while holding a spinlock, or with +preemption disabled. This also means you need to be in user context: +calling them from an interrupt is illegal. + +Some Functions Which Sleep +-------------------------- + +The most common ones are listed below, but you usually have to read the +code to find out if other calls are safe. If everyone else who calls it +can sleep, you probably need to be able to sleep, too. In particular, +registration and deregistration functions usually expect to be called +from user context, and can sleep. + +- Accesses to userspace: + + - :c:func:`copy_from_user()` + + - :c:func:`copy_to_user()` + + - :c:func:`get_user()` + + - :c:func:`put_user()` + +- :c:func:`kmalloc(GFP_KERNEL) <kmalloc>` + +- :c:func:`mutex_lock_interruptible()` and + :c:func:`mutex_lock()` + + There is a :c:func:`mutex_trylock()` which does not sleep. + Still, it must not be used inside interrupt context since its + implementation is not safe for that. :c:func:`mutex_unlock()` + will also never sleep. It cannot be used in interrupt context either + since a mutex must be released by the same task that acquired it. + +Some Functions Which Don't Sleep +-------------------------------- + +Some functions are safe to call from any context, or holding almost any +lock. + +- :c:func:`printk()` + +- :c:func:`kfree()` + +- :c:func:`add_timer()` and :c:func:`del_timer()` + +Mutex API reference +=================== + +.. kernel-doc:: include/linux/mutex.h + :internal: + +.. kernel-doc:: kernel/locking/mutex.c + :export: + +Futex API reference +=================== + +.. kernel-doc:: kernel/futex.c + :internal: + +Further reading +=============== + +- ``Documentation/locking/spinlocks.txt``: Linus Torvalds' spinlocking + tutorial in the kernel sources. + +- Unix Systems for Modern Architectures: Symmetric Multiprocessing and + Caching for Kernel Programmers: + + Curt Schimmel's very good introduction to kernel level locking (not + written for Linux, but nearly everything applies). The book is + expensive, but really worth every penny to understand SMP locking. + [ISBN: 0201633388] + +Thanks +====== + +Thanks to Telsa Gwynne for DocBooking, neatening and adding style. + +Thanks to Martin Pool, Philipp Rumpf, Stephen Rothwell, Paul Mackerras, +Ruedi Aschwanden, Alan Cox, Manfred Spraul, Tim Waugh, Pete Zaitcev, +James Morris, Robert Love, Paul McKenney, John Ashby for proofreading, +correcting, flaming, commenting. + +Thanks to the cabal for having no influence on this document. + +Glossary +======== + +preemption + Prior to 2.5, or when ``CONFIG_PREEMPT`` is unset, processes in user + context inside the kernel would not preempt each other (ie. you had that + CPU until you gave it up, except for interrupts). With the addition of + ``CONFIG_PREEMPT`` in 2.5.4, this changed: when in user context, higher + priority tasks can "cut in": spinlocks were changed to disable + preemption, even on UP. + +bh + Bottom Half: for historical reasons, functions with '_bh' in them often + now refer to any software interrupt, e.g. :c:func:`spin_lock_bh()` + blocks any software interrupt on the current CPU. Bottom halves are + deprecated, and will eventually be replaced by tasklets. Only one bottom + half will be running at any time. + +Hardware Interrupt / Hardware IRQ + Hardware interrupt request. :c:func:`in_irq()` returns true in a + hardware interrupt handler. + +Interrupt Context + Not user context: processing a hardware irq or software irq. Indicated + by the :c:func:`in_interrupt()` macro returning true. + +SMP + Symmetric Multi-Processor: kernels compiled for multiple-CPU machines. + (``CONFIG_SMP=y``). + +Software Interrupt / softirq + Software interrupt handler. :c:func:`in_irq()` returns false; + :c:func:`in_softirq()` returns true. Tasklets and softirqs both + fall into the category of 'software interrupts'. + + Strictly speaking a softirq is one of up to 32 enumerated software + interrupts which can run on multiple CPUs at once. Sometimes used to + refer to tasklets as well (ie. all software interrupts). + +tasklet + A dynamically-registrable software interrupt, which is guaranteed to + only run on one CPU at a time. + +timer + A dynamically-registrable software interrupt, which is run at (or close + to) a given time. When running, it is just like a tasklet (in fact, they + are called from the ``TIMER_SOFTIRQ``). + +UP + Uni-Processor: Non-SMP. (``CONFIG_SMP=n``). + +User Context + The kernel executing on behalf of a particular process (ie. a system + call or trap) or kernel thread. You can tell which process with the + ``current`` macro.) Not to be confused with userspace. Can be + interrupted by software or hardware interrupts. + +Userspace + A process executing its own code outside the kernel. diff --git a/Documentation/kernel-per-CPU-kthreads.txt b/Documentation/kernel-per-CPU-kthreads.txt index df31e30b6a02..2cb7dc5c0e0d 100644 --- a/Documentation/kernel-per-CPU-kthreads.txt +++ b/Documentation/kernel-per-CPU-kthreads.txt @@ -109,13 +109,12 @@ SCHED_SOFTIRQ: Do all of the following: on that CPU. If a thread that expects to run on the de-jittered CPU awakens, the scheduler will send an IPI that can result in a subsequent SCHED_SOFTIRQ. -2. Build with CONFIG_RCU_NOCB_CPU=y, CONFIG_RCU_NOCB_CPU_ALL=y, - CONFIG_NO_HZ_FULL=y, and, in addition, ensure that the CPU - to be de-jittered is marked as an adaptive-ticks CPU using the - "nohz_full=" boot parameter. This reduces the number of - scheduler-clock interrupts that the de-jittered CPU receives, - minimizing its chances of being selected to do the load balancing - work that runs in SCHED_SOFTIRQ context. +2. CONFIG_NO_HZ_FULL=y and ensure that the CPU to be de-jittered + is marked as an adaptive-ticks CPU using the "nohz_full=" + boot parameter. This reduces the number of scheduler-clock + interrupts that the de-jittered CPU receives, minimizing its + chances of being selected to do the load balancing work that + runs in SCHED_SOFTIRQ context. 3. To the extent possible, keep the CPU out of the kernel when it is non-idle, for example, by avoiding system calls and by forcing both kernel threads and interrupts to execute elsewhere. @@ -135,11 +134,10 @@ HRTIMER_SOFTIRQ: Do all of the following: RCU_SOFTIRQ: Do at least one of the following: 1. Offload callbacks and keep the CPU in either dyntick-idle or adaptive-ticks state by doing all of the following: - a. Build with CONFIG_RCU_NOCB_CPU=y, CONFIG_RCU_NOCB_CPU_ALL=y, - CONFIG_NO_HZ_FULL=y, and, in addition ensure that the CPU - to be de-jittered is marked as an adaptive-ticks CPU using - the "nohz_full=" boot parameter. Bind the rcuo kthreads - to housekeeping CPUs, which can tolerate OS jitter. + a. CONFIG_NO_HZ_FULL=y and ensure that the CPU to be + de-jittered is marked as an adaptive-ticks CPU using the + "nohz_full=" boot parameter. Bind the rcuo kthreads to + housekeeping CPUs, which can tolerate OS jitter. b. To the extent possible, keep the CPU out of the kernel when it is non-idle, for example, by avoiding system calls and by forcing both kernel threads and interrupts @@ -236,11 +234,10 @@ To reduce its OS jitter, do at least one of the following: is feasible only if your workload never requires RCU priority boosting, for example, if you ensure frequent idle time on all CPUs that might execute within the kernel. -3. Build with CONFIG_RCU_NOCB_CPU=y and CONFIG_RCU_NOCB_CPU_ALL=y, - which offloads all RCU callbacks to kthreads that can be moved - off of CPUs susceptible to OS jitter. This approach prevents the - rcuc/%u kthreads from having any work to do, so that they are - never awakened. +3. Build with CONFIG_RCU_NOCB_CPU=y and boot with the rcu_nocbs= + boot parameter offloading RCU callbacks from all CPUs susceptible + to OS jitter. This approach prevents the rcuc/%u kthreads from + having any work to do, so that they are never awakened. 4. Ensure that the CPU never enters the kernel, and, in particular, avoid initiating any CPU hotplug operations on this CPU. This is another way of preventing any callbacks from being queued on the diff --git a/Documentation/lsm.txt b/Documentation/lsm.txt new file mode 100644 index 000000000000..ad4dfd020e0d --- /dev/null +++ b/Documentation/lsm.txt @@ -0,0 +1,201 @@ +======================================================== +Linux Security Modules: General Security Hooks for Linux +======================================================== + +:Author: Stephen Smalley +:Author: Timothy Fraser +:Author: Chris Vance + +.. note:: + + The APIs described in this book are outdated. + +Introduction +============ + +In March 2001, the National Security Agency (NSA) gave a presentation +about Security-Enhanced Linux (SELinux) at the 2.5 Linux Kernel Summit. +SELinux is an implementation of flexible and fine-grained +nondiscretionary access controls in the Linux kernel, originally +implemented as its own particular kernel patch. Several other security +projects (e.g. RSBAC, Medusa) have also developed flexible access +control architectures for the Linux kernel, and various projects have +developed particular access control models for Linux (e.g. LIDS, DTE, +SubDomain). Each project has developed and maintained its own kernel +patch to support its security needs. + +In response to the NSA presentation, Linus Torvalds made a set of +remarks that described a security framework he would be willing to +consider for inclusion in the mainstream Linux kernel. He described a +general framework that would provide a set of security hooks to control +operations on kernel objects and a set of opaque security fields in +kernel data structures for maintaining security attributes. This +framework could then be used by loadable kernel modules to implement any +desired model of security. Linus also suggested the possibility of +migrating the Linux capabilities code into such a module. + +The Linux Security Modules (LSM) project was started by WireX to develop +such a framework. LSM is a joint development effort by several security +projects, including Immunix, SELinux, SGI and Janus, and several +individuals, including Greg Kroah-Hartman and James Morris, to develop a +Linux kernel patch that implements this framework. The patch is +currently tracking the 2.4 series and is targeted for integration into +the 2.5 development series. This technical report provides an overview +of the framework and the example capabilities security module provided +by the LSM kernel patch. + +LSM Framework +============= + +The LSM kernel patch provides a general kernel framework to support +security modules. In particular, the LSM framework is primarily focused +on supporting access control modules, although future development is +likely to address other security needs such as auditing. By itself, the +framework does not provide any additional security; it merely provides +the infrastructure to support security modules. The LSM kernel patch +also moves most of the capabilities logic into an optional security +module, with the system defaulting to the traditional superuser logic. +This capabilities module is discussed further in +`LSM Capabilities Module <#cap>`__. + +The LSM kernel patch adds security fields to kernel data structures and +inserts calls to hook functions at critical points in the kernel code to +manage the security fields and to perform access control. It also adds +functions for registering and unregistering security modules, and adds a +general :c:func:`security()` system call to support new system calls +for security-aware applications. + +The LSM security fields are simply ``void*`` pointers. For process and +program execution security information, security fields were added to +:c:type:`struct task_struct <task_struct>` and +:c:type:`struct linux_binprm <linux_binprm>`. For filesystem +security information, a security field was added to :c:type:`struct +super_block <super_block>`. For pipe, file, and socket security +information, security fields were added to :c:type:`struct inode +<inode>` and :c:type:`struct file <file>`. For packet and +network device security information, security fields were added to +:c:type:`struct sk_buff <sk_buff>` and :c:type:`struct +net_device <net_device>`. For System V IPC security information, +security fields were added to :c:type:`struct kern_ipc_perm +<kern_ipc_perm>` and :c:type:`struct msg_msg +<msg_msg>`; additionally, the definitions for :c:type:`struct +msg_msg <msg_msg>`, struct msg_queue, and struct shmid_kernel +were moved to header files (``include/linux/msg.h`` and +``include/linux/shm.h`` as appropriate) to allow the security modules to +use these definitions. + +Each LSM hook is a function pointer in a global table, security_ops. +This table is a :c:type:`struct security_operations +<security_operations>` structure as defined by +``include/linux/security.h``. Detailed documentation for each hook is +included in this header file. At present, this structure consists of a +collection of substructures that group related hooks based on the kernel +object (e.g. task, inode, file, sk_buff, etc) as well as some top-level +hook function pointers for system operations. This structure is likely +to be flattened in the future for performance. The placement of the hook +calls in the kernel code is described by the "called:" lines in the +per-hook documentation in the header file. The hook calls can also be +easily found in the kernel code by looking for the string +"security_ops->". + +Linus mentioned per-process security hooks in his original remarks as a +possible alternative to global security hooks. However, if LSM were to +start from the perspective of per-process hooks, then the base framework +would have to deal with how to handle operations that involve multiple +processes (e.g. kill), since each process might have its own hook for +controlling the operation. This would require a general mechanism for +composing hooks in the base framework. Additionally, LSM would still +need global hooks for operations that have no process context (e.g. +network input operations). Consequently, LSM provides global security +hooks, but a security module is free to implement per-process hooks +(where that makes sense) by storing a security_ops table in each +process' security field and then invoking these per-process hooks from +the global hooks. The problem of composition is thus deferred to the +module. + +The global security_ops table is initialized to a set of hook functions +provided by a dummy security module that provides traditional superuser +logic. A :c:func:`register_security()` function (in +``security/security.c``) is provided to allow a security module to set +security_ops to refer to its own hook functions, and an +:c:func:`unregister_security()` function is provided to revert +security_ops to the dummy module hooks. This mechanism is used to set +the primary security module, which is responsible for making the final +decision for each hook. + +LSM also provides a simple mechanism for stacking additional security +modules with the primary security module. It defines +:c:func:`register_security()` and +:c:func:`unregister_security()` hooks in the :c:type:`struct +security_operations <security_operations>` structure and +provides :c:func:`mod_reg_security()` and +:c:func:`mod_unreg_security()` functions that invoke these hooks +after performing some sanity checking. A security module can call these +functions in order to stack with other modules. However, the actual +details of how this stacking is handled are deferred to the module, +which can implement these hooks in any way it wishes (including always +returning an error if it does not wish to support stacking). In this +manner, LSM again defers the problem of composition to the module. + +Although the LSM hooks are organized into substructures based on kernel +object, all of the hooks can be viewed as falling into two major +categories: hooks that are used to manage the security fields and hooks +that are used to perform access control. Examples of the first category +of hooks include the :c:func:`alloc_security()` and +:c:func:`free_security()` hooks defined for each kernel data +structure that has a security field. These hooks are used to allocate +and free security structures for kernel objects. The first category of +hooks also includes hooks that set information in the security field +after allocation, such as the :c:func:`post_lookup()` hook in +:c:type:`struct inode_security_ops <inode_security_ops>`. +This hook is used to set security information for inodes after +successful lookup operations. An example of the second category of hooks +is the :c:func:`permission()` hook in :c:type:`struct +inode_security_ops <inode_security_ops>`. This hook checks +permission when accessing an inode. + +LSM Capabilities Module +======================= + +The LSM kernel patch moves most of the existing POSIX.1e capabilities +logic into an optional security module stored in the file +``security/capability.c``. This change allows users who do not want to +use capabilities to omit this code entirely from their kernel, instead +using the dummy module for traditional superuser logic or any other +module that they desire. This change also allows the developers of the +capabilities logic to maintain and enhance their code more freely, +without needing to integrate patches back into the base kernel. + +In addition to moving the capabilities logic, the LSM kernel patch could +move the capability-related fields from the kernel data structures into +the new security fields managed by the security modules. However, at +present, the LSM kernel patch leaves the capability fields in the kernel +data structures. In his original remarks, Linus suggested that this +might be preferable so that other security modules can be easily stacked +with the capabilities module without needing to chain multiple security +structures on the security field. It also avoids imposing extra overhead +on the capabilities module to manage the security fields. However, the +LSM framework could certainly support such a move if it is determined to +be desirable, with only a few additional changes described below. + +At present, the capabilities logic for computing process capabilities on +:c:func:`execve()` and :c:func:`set\*uid()`, checking +capabilities for a particular process, saving and checking capabilities +for netlink messages, and handling the :c:func:`capget()` and +:c:func:`capset()` system calls have been moved into the +capabilities module. There are still a few locations in the base kernel +where capability-related fields are directly examined or modified, but +the current version of the LSM patch does allow a security module to +completely replace the assignment and testing of capabilities. These few +locations would need to be changed if the capability-related fields were +moved into the security field. The following is a list of known +locations that still perform such direct examination or modification of +capability-related fields: + +- ``fs/open.c``::c:func:`sys_access()` + +- ``fs/lockd/host.c``::c:func:`nlm_bind_host()` + +- ``fs/nfsd/auth.c``::c:func:`nfsd_setuser()` + +- ``fs/proc/array.c``::c:func:`task_cap()` diff --git a/Documentation/media/uapi/v4l/vidioc-g-selection.rst b/Documentation/media/uapi/v4l/vidioc-g-selection.rst index deb1f6fb473b..b80d85cb8891 100644 --- a/Documentation/media/uapi/v4l/vidioc-g-selection.rst +++ b/Documentation/media/uapi/v4l/vidioc-g-selection.rst @@ -129,8 +129,8 @@ Selection targets and flags are documented in .. _sel-const-adjust: -.. figure:: constraints.* - :alt: constraints.pdf / constraints.svg +.. kernel-figure:: constraints.svg + :alt: constraints.svg :align: center Size adjustments with constraint flags. diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index 732f10ea382e..c239a0cf4b1a 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -27,7 +27,7 @@ The purpose of this document is twofold: (2) to provide a guide as to how to use the barriers that are available. Note that an architecture can provide more than the minimum requirement -for any particular barrier, but if the architecure provides less than +for any particular barrier, but if the architecture provides less than that, that architecture is incorrect. Note also that it is possible that a barrier may be a no-op for an @@ -498,11 +498,11 @@ And a couple of implicit varieties: This means that ACQUIRE acts as a minimal "acquire" operation and RELEASE acts as a minimal "release" operation. -A subset of the atomic operations described in atomic_ops.txt have ACQUIRE -and RELEASE variants in addition to fully-ordered and relaxed (no barrier -semantics) definitions. For compound atomics performing both a load and a -store, ACQUIRE semantics apply only to the load and RELEASE semantics apply -only to the store portion of the operation. +A subset of the atomic operations described in core-api/atomic_ops.rst have +ACQUIRE and RELEASE variants in addition to fully-ordered and relaxed (no +barrier semantics) definitions. For compound atomics performing both a load +and a store, ACQUIRE semantics apply only to the load and RELEASE semantics +apply only to the store portion of the operation. Memory barriers are only required where there's a possibility of interaction between two CPUs or between a CPU and a device. If it can be guaranteed that diff --git a/Documentation/networking/checksum-offloads.txt b/Documentation/networking/checksum-offloads.txt index 56e36861245f..d52d191bbb0c 100644 --- a/Documentation/networking/checksum-offloads.txt +++ b/Documentation/networking/checksum-offloads.txt @@ -35,6 +35,9 @@ This interface only allows a single checksum to be offloaded. Where encapsulation is used, the packet may have multiple checksum fields in different header layers, and the rest will have to be handled by another mechanism such as LCO or RCO. +CRC32c can also be offloaded using this interface, by means of filling + skb->csum_start and skb->csum_offset as described above, and setting + skb->csum_not_inet: see skbuff.h comment (section 'D') for more details. No offloading of the IP header checksum is performed; it is always done in software. This is OK because when we build the IP header, we obviously have it in cache, so summing it isn't expensive. It's also rather short. @@ -49,9 +52,9 @@ A driver declares its offload capabilities in netdev->hw_features; see and csum_offset given in the SKB; if it tries to deduce these itself in hardware (as some NICs do) the driver should check that the values in the SKB match those which the hardware will deduce, and if not, fall back to - checksumming in software instead (with skb_checksum_help or one of the - skb_csum_off_chk* functions as mentioned in include/linux/skbuff.h). This - is a pain, but that's what you get when hardware tries to be clever. + checksumming in software instead (with skb_csum_hwoffload_help() or one of + the skb_checksum_help() / skb_crc32c_csum_help functions, as mentioned in + include/linux/skbuff.h). The stack should, for the most part, assume that checksum offload is supported by the underlying device. The only place that should check is @@ -60,7 +63,7 @@ The stack should, for the most part, assume that checksum offload is may include other offloads besides TX Checksum Offload) and, if they are not supported or enabled on the device (determined by netdev->features), performs the corresponding offload in software. In the case of TX - Checksum Offload, that means calling skb_checksum_help(skb). + Checksum Offload, that means calling skb_csum_hwoffload_help(skb, features). LCO: Local Checksum Offload diff --git a/Documentation/networking/conf.py b/Documentation/networking/conf.py new file mode 100644 index 000000000000..40f69e67a883 --- /dev/null +++ b/Documentation/networking/conf.py @@ -0,0 +1,10 @@ +# -*- coding: utf-8; mode: python -*- + +project = "Linux Networking Documentation" + +tags.add("subproject") + +latex_documents = [ + ('index', 'networking.tex', project, + 'The kernel development community', 'manual'), +] diff --git a/Documentation/networking/dns_resolver.txt b/Documentation/networking/dns_resolver.txt index d86adcdae420..eaa8f9a6fd5d 100644 --- a/Documentation/networking/dns_resolver.txt +++ b/Documentation/networking/dns_resolver.txt @@ -143,7 +143,7 @@ the key will be discarded and recreated when the data it holds has expired. dns_query() returns a copy of the value attached to the key, or an error if that is indicated instead. -See <file:Documentation/security/keys-request-key.txt> for further +See <file:Documentation/security/keys/request-key.rst> for further information about request-key function. diff --git a/Documentation/networking/dpaa.txt b/Documentation/networking/dpaa.txt new file mode 100644 index 000000000000..76e016d4d344 --- /dev/null +++ b/Documentation/networking/dpaa.txt @@ -0,0 +1,194 @@ +The QorIQ DPAA Ethernet Driver +============================== + +Authors: +Madalin Bucur <madalin.bucur@nxp.com> +Camelia Groza <camelia.groza@nxp.com> + +Contents +======== + + - DPAA Ethernet Overview + - DPAA Ethernet Supported SoCs + - Configuring DPAA Ethernet in your kernel + - DPAA Ethernet Frame Processing + - DPAA Ethernet Features + - Debugging + +DPAA Ethernet Overview +====================== + +DPAA stands for Data Path Acceleration Architecture and it is a +set of networking acceleration IPs that are available on several +generations of SoCs, both on PowerPC and ARM64. + +The Freescale DPAA architecture consists of a series of hardware blocks +that support Ethernet connectivity. The Ethernet driver depends upon the +following drivers in the Linux kernel: + + - Peripheral Access Memory Unit (PAMU) (* needed only for PPC platforms) + drivers/iommu/fsl_* + - Frame Manager (FMan) + drivers/net/ethernet/freescale/fman + - Queue Manager (QMan), Buffer Manager (BMan) + drivers/soc/fsl/qbman + +A simplified view of the dpaa_eth interfaces mapped to FMan MACs: + + dpaa_eth /eth0\ ... /ethN\ + driver | | | | + ------------- ---- ----------- ---- ------------- + -Ports / Tx Rx \ ... / Tx Rx \ + FMan | | | | + -MACs | MAC0 | | MACN | + / dtsec0 \ ... / dtsecN \ (or tgec) + / \ / \(or memac) + --------- -------------- --- -------------- --------- + FMan, FMan Port, FMan SP, FMan MURAM drivers + --------------------------------------------------------- + FMan HW blocks: MURAM, MACs, Ports, SP + --------------------------------------------------------- + +The dpaa_eth relation to the QMan, BMan and FMan: + ________________________________ + dpaa_eth / eth0 \ + driver / \ + --------- -^- -^- -^- --- --------- + QMan driver / \ / \ / \ \ / | BMan | + |Rx | |Rx | |Tx | |Tx | | driver | + --------- |Dfl| |Err| |Cnf| |FQs| | | + QMan HW |FQ | |FQ | |FQs| | | | | + / \ / \ / \ \ / | | + --------- --- --- --- -v- --------- + | FMan QMI | | + | FMan HW FMan BMI | BMan HW | + ----------------------- -------- + +where the acronyms used above (and in the code) are: +DPAA = Data Path Acceleration Architecture +FMan = DPAA Frame Manager +QMan = DPAA Queue Manager +BMan = DPAA Buffers Manager +QMI = QMan interface in FMan +BMI = BMan interface in FMan +FMan SP = FMan Storage Profiles +MURAM = Multi-user RAM in FMan +FQ = QMan Frame Queue +Rx Dfl FQ = default reception FQ +Rx Err FQ = Rx error frames FQ +Tx Cnf FQ = Tx confirmation FQs +Tx FQs = transmission frame queues +dtsec = datapath three speed Ethernet controller (10/100/1000 Mbps) +tgec = ten gigabit Ethernet controller (10 Gbps) +memac = multirate Ethernet MAC (10/100/1000/10000) + +DPAA Ethernet Supported SoCs +============================ + +The DPAA drivers enable the Ethernet controllers present on the following SoCs: + +# PPC +P1023 +P2041 +P3041 +P4080 +P5020 +P5040 +T1023 +T1024 +T1040 +T1042 +T2080 +T4240 +B4860 + +# ARM +LS1043A +LS1046A + +Configuring DPAA Ethernet in your kernel +======================================== + +To enable the DPAA Ethernet driver, the following Kconfig options are required: + +# common for arch/arm64 and arch/powerpc platforms +CONFIG_FSL_DPAA=y +CONFIG_FSL_FMAN=y +CONFIG_FSL_DPAA_ETH=y +CONFIG_FSL_XGMAC_MDIO=y + +# for arch/powerpc only +CONFIG_FSL_PAMU=y + +# common options needed for the PHYs used on the RDBs +CONFIG_VITESSE_PHY=y +CONFIG_REALTEK_PHY=y +CONFIG_AQUANTIA_PHY=y + +DPAA Ethernet Frame Processing +============================== + +On Rx, buffers for the incoming frames are retrieved from one of the three +existing buffers pools. The driver initializes and seeds these, each with +buffers of different sizes: 1KB, 2KB and 4KB. + +On Tx, all transmitted frames are returned to the driver through Tx +confirmation frame queues. The driver is then responsible for freeing the +buffers. In order to do this properly, a backpointer is added to the buffer +before transmission that points to the skb. When the buffer returns to the +driver on a confirmation FQ, the skb can be correctly consumed. + +DPAA Ethernet Features +====================== + +Currently the DPAA Ethernet driver enables the basic features required for +a Linux Ethernet driver. The support for advanced features will be added +gradually. + +The driver has Rx and Tx checksum offloading for UDP and TCP. Currently the Rx +checksum offload feature is enabled by default and cannot be controlled through +ethtool. + +The driver has support for multiple prioritized Tx traffic classes. Priorities +range from 0 (lowest) to 3 (highest). These are mapped to HW workqueues with +strict priority levels. Each traffic class contains NR_CPU TX queues. By +default, only one traffic class is enabled and the lowest priority Tx queues +are used. Higher priority traffic classes can be enabled with the mqprio +qdisc. For example, all four traffic classes are enabled on an interface with +the following command. Furthermore, skb priority levels are mapped to traffic +classes as follows: + + * priorities 0 to 3 - traffic class 0 (low priority) + * priorities 4 to 7 - traffic class 1 (medium-low priority) + * priorities 8 to 11 - traffic class 2 (medium-high priority) + * priorities 12 to 15 - traffic class 3 (high priority) + +tc qdisc add dev <int> root handle 1: \ + mqprio num_tc 4 map 0 0 0 0 1 1 1 1 2 2 2 2 3 3 3 3 hw 1 + +Debugging +========= + +The following statistics are exported for each interface through ethtool: + + - interrupt count per CPU + - Rx packets count per CPU + - Tx packets count per CPU + - Tx confirmed packets count per CPU + - Tx S/G frames count per CPU + - Tx error count per CPU + - Rx error count per CPU + - Rx error count per type + - congestion related statistics: + - congestion status + - time spent in congestion + - number of time the device entered congestion + - dropped packets count per cause + +The driver also exports the following information in sysfs: + + - the FQ IDs for each FQ type + /sys/devices/platform/dpaa-ethernet.0/net/<int>/fqids + + - the IDs of the buffer pools in use + /sys/devices/platform/dpaa-ethernet.0/net/<int>/bpids diff --git a/Documentation/networking/i40evf.txt b/Documentation/networking/i40evf.txt index 21e41271af79..e9b3035b95d0 100644 --- a/Documentation/networking/i40evf.txt +++ b/Documentation/networking/i40evf.txt @@ -1,8 +1,8 @@ Linux* Base Driver for Intel(R) Network Connection ================================================== -Intel XL710 X710 Virtual Function Linux driver. -Copyright(c) 2013 Intel Corporation. +Intel Ethernet Adaptive Virtual Function Linux driver. +Copyright(c) 2013-2017 Intel Corporation. Contents ======== @@ -11,19 +11,26 @@ Contents - Known Issues/Troubleshooting - Support -This file describes the i40evf Linux* Base Driver for the Intel(R) XL710 -X710 Virtual Function. +This file describes the i40evf Linux* Base Driver. -The i40evf driver supports XL710 and X710 virtual function devices that -can only be activated on kernels with CONFIG_PCI_IOV enabled. +The i40evf driver supports the below mentioned virtual function +devices and can only be activated on kernels running the i40e or +newer Physical Function (PF) driver compiled with CONFIG_PCI_IOV. +The i40evf driver requires CONFIG_PCI_MSI to be enabled. The guest OS loading the i40evf driver must support MSI-X interrupts. +Supported Hardware +================== +Intel XL710 X710 Virtual Function +Intel Ethernet Adaptive Virtual Function +Intel X722 Virtual Function + Identifying Your Adapter ======================== -For more information on how to identify your adapter, go to the Adapter & -Driver ID Guide at: +For more information on how to identify your adapter, go to the +Adapter & Driver ID Guide at: http://support.intel.com/support/go/network/adapter/idguide.htm diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst new file mode 100644 index 000000000000..b5bd87e01f52 --- /dev/null +++ b/Documentation/networking/index.rst @@ -0,0 +1,18 @@ +Linux Networking Documentation +============================== + +Contents: + +.. toctree:: + :maxdepth: 2 + + kapi + z8530book + +.. only:: subproject + + Indices + ======= + + * :ref:`genindex` + diff --git a/Documentation/networking/ipvlan.txt b/Documentation/networking/ipvlan.txt index 24196cef7c91..1fe42a874aae 100644 --- a/Documentation/networking/ipvlan.txt +++ b/Documentation/networking/ipvlan.txt @@ -22,9 +22,9 @@ The driver can be built into the kernel (CONFIG_IPVLAN=y) or as a module There are no module parameters for this driver and it can be configured using IProute2/ip utility. - ip link add link <master-dev> <slave-dev> type ipvlan mode { l2 | l3 | l3s } + ip link add link <master-dev> name <slave-dev> type ipvlan mode { l2 | l3 | l3s } - e.g. ip link add link ipvl0 eth0 type ipvlan mode l2 + e.g. ip link add link eth0 name ipvl0 type ipvlan mode l2 4. Operating modes: diff --git a/Documentation/networking/kapi.rst b/Documentation/networking/kapi.rst new file mode 100644 index 000000000000..580289f345da --- /dev/null +++ b/Documentation/networking/kapi.rst @@ -0,0 +1,147 @@ +========================================= +Linux Networking and Network Devices APIs +========================================= + +Linux Networking +================ + +Networking Base Types +--------------------- + +.. kernel-doc:: include/linux/net.h + :internal: + +Socket Buffer Functions +----------------------- + +.. kernel-doc:: include/linux/skbuff.h + :internal: + +.. kernel-doc:: include/net/sock.h + :internal: + +.. kernel-doc:: net/socket.c + :export: + +.. kernel-doc:: net/core/skbuff.c + :export: + +.. kernel-doc:: net/core/sock.c + :export: + +.. kernel-doc:: net/core/datagram.c + :export: + +.. kernel-doc:: net/core/stream.c + :export: + +Socket Filter +------------- + +.. kernel-doc:: net/core/filter.c + :export: + +Generic Network Statistics +-------------------------- + +.. kernel-doc:: include/uapi/linux/gen_stats.h + :internal: + +.. kernel-doc:: net/core/gen_stats.c + :export: + +.. kernel-doc:: net/core/gen_estimator.c + :export: + +SUN RPC subsystem +----------------- + +.. kernel-doc:: net/sunrpc/xdr.c + :export: + +.. kernel-doc:: net/sunrpc/svc_xprt.c + :export: + +.. kernel-doc:: net/sunrpc/xprt.c + :export: + +.. kernel-doc:: net/sunrpc/sched.c + :export: + +.. kernel-doc:: net/sunrpc/socklib.c + :export: + +.. kernel-doc:: net/sunrpc/stats.c + :export: + +.. kernel-doc:: net/sunrpc/rpc_pipe.c + :export: + +.. kernel-doc:: net/sunrpc/rpcb_clnt.c + :export: + +.. kernel-doc:: net/sunrpc/clnt.c + :export: + +WiMAX +----- + +.. kernel-doc:: net/wimax/op-msg.c + :export: + +.. kernel-doc:: net/wimax/op-reset.c + :export: + +.. kernel-doc:: net/wimax/op-rfkill.c + :export: + +.. kernel-doc:: net/wimax/stack.c + :export: + +.. kernel-doc:: include/net/wimax.h + :internal: + +.. kernel-doc:: include/uapi/linux/wimax.h + :internal: + +Network device support +====================== + +Driver Support +-------------- + +.. kernel-doc:: net/core/dev.c + :export: + +.. kernel-doc:: net/ethernet/eth.c + :export: + +.. kernel-doc:: net/sched/sch_generic.c + :export: + +.. kernel-doc:: include/linux/etherdevice.h + :internal: + +.. kernel-doc:: include/linux/netdevice.h + :internal: + +PHY Support +----------- + +.. kernel-doc:: drivers/net/phy/phy.c + :export: + +.. kernel-doc:: drivers/net/phy/phy.c + :internal: + +.. kernel-doc:: drivers/net/phy/phy_device.c + :export: + +.. kernel-doc:: drivers/net/phy/phy_device.c + :internal: + +.. kernel-doc:: drivers/net/phy/mdio_bus.c + :export: + +.. kernel-doc:: drivers/net/phy/mdio_bus.c + :internal: diff --git a/Documentation/networking/phy.txt b/Documentation/networking/phy.txt index 16f90d817224..bdec0f700bc1 100644 --- a/Documentation/networking/phy.txt +++ b/Documentation/networking/phy.txt @@ -295,7 +295,6 @@ Doing it all yourself settings in the PHY. int phy_ethtool_sset(struct phy_device *phydev, struct ethtool_cmd *cmd); - int phy_ethtool_gset(struct phy_device *phydev, struct ethtool_cmd *cmd); Ethtool convenience functions. diff --git a/Documentation/networking/policy-routing.txt b/Documentation/networking/policy-routing.txt deleted file mode 100644 index 36f6936d7f21..000000000000 --- a/Documentation/networking/policy-routing.txt +++ /dev/null @@ -1,150 +0,0 @@ -Classes -------- - - "Class" is a complete routing table in common sense. - I.e. it is tree of nodes (destination prefix, tos, metric) - with attached information: gateway, device etc. - This tree is looked up as specified in RFC1812 5.2.4.3 - 1. Basic match - 2. Longest match - 3. Weak TOS. - 4. Metric. (should not be in kernel space, but they are) - 5. Additional pruning rules. (not in kernel space). - - We have two special type of nodes: - REJECT - abort route lookup and return an error value. - THROW - abort route lookup in this class. - - - Currently the number of classes is limited to 255 - (0 is reserved for "not specified class") - - Three classes are builtin: - - RT_CLASS_LOCAL=255 - local interface addresses, - broadcasts, nat addresses. - - RT_CLASS_MAIN=254 - all normal routes are put there - by default. - - RT_CLASS_DEFAULT=253 - if ip_fib_model==1, then - normal default routes are put there, if ip_fib_model==2 - all gateway routes are put there. - - -Rules ------ - Rule is a record of (src prefix, src interface, tos, dst prefix) - with attached information. - - Rule types: - RTP_ROUTE - lookup in attached class - RTP_NAT - lookup in attached class and if a match is found, - translate packet source address. - RTP_MASQUERADE - lookup in attached class and if a match is found, - masquerade packet as sourced by us. - RTP_DROP - silently drop the packet. - RTP_REJECT - drop the packet and send ICMP NET UNREACHABLE. - RTP_PROHIBIT - drop the packet and send ICMP COMM. ADM. PROHIBITED. - - Rule flags: - RTRF_LOG - log route creations. - RTRF_VALVE - One way route (used with masquerading) - -Default setup: - -root@amber:/pub/ip-routing # iproute -r -Kernel routing policy rules -Pref Source Destination TOS Iface Cl - 0 default default 00 * 255 - 254 default default 00 * 254 - 255 default default 00 * 253 - - -Lookup algorithm ----------------- - - We scan rules list, and if a rule is matched, apply it. - If a route is found, return it. - If it is not found or a THROW node was matched, continue - to scan rules. - -Applications ------------- - -1. Just ignore classes. All the routes are put into MAIN class - (and/or into DEFAULT class). - - HOWTO: iproute add PREFIX [ tos TOS ] [ gw GW ] [ dev DEV ] - [ metric METRIC ] [ reject ] ... (look at iproute utility) - - or use route utility from current net-tools. - -2. Opposite case. Just forget all that you know about routing - tables. Every rule is supplied with its own gateway, device - info. record. This approach is not appropriate for automated - route maintenance, but it is ideal for manual configuration. - - HOWTO: iproute addrule [ from PREFIX ] [ to PREFIX ] [ tos TOS ] - [ dev INPUTDEV] [ pref PREFERENCE ] route [ gw GATEWAY ] - [ dev OUTDEV ] ..... - - Warning: As of now the size of the routing table in this - approach is limited to 256. If someone likes this model, I'll - relax this limitation. - -3. OSPF classes (see RFC1583, RFC1812 E.3.3) - Very clean, stable and robust algorithm for OSPF routing - domains. Unfortunately, it is not widely used in the Internet. - - Proposed setup: - 255 local addresses - 254 interface routes - 253 ASE routes with external metric - 252 ASE routes with internal metric - 251 inter-area routes - 250 intra-area routes for 1st area - 249 intra-area routes for 2nd area - etc. - - Rules: - iproute addrule class 253 - iproute addrule class 252 - iproute addrule class 251 - iproute addrule to a-prefix-for-1st-area class 250 - iproute addrule to another-prefix-for-1st-area class 250 - ... - iproute addrule to a-prefix-for-2nd-area class 249 - ... - - Area classes must be terminated with reject record. - iproute add default reject class 250 - iproute add default reject class 249 - ... - -4. The Variant Router Requirements Algorithm (RFC1812 E.3.2) - Create 16 classes for different TOS values. - It is a funny, but pretty useless algorithm. - I listed it just to show the power of new routing code. - -5. All the variety of combinations...... - - -GATED ------ - - Gated does not understand classes, but it will work - happily in MAIN+DEFAULT. All policy routes can be set - and maintained manually. - -IMPORTANT NOTE --------------- - route.c has a compilation time switch CONFIG_IP_LOCAL_RT_POLICY. - If it is set, locally originated packets are routed - using all the policy list. This is not very convenient and - pretty ambiguous when used with NAT and masquerading. - I set it to FALSE by default. - - -Alexey Kuznetov -kuznet@ms2.inr.ac.ru diff --git a/Documentation/networking/rxrpc.txt b/Documentation/networking/rxrpc.txt index 1b63bbc6b94f..8c70ba5dee4d 100644 --- a/Documentation/networking/rxrpc.txt +++ b/Documentation/networking/rxrpc.txt @@ -325,6 +325,9 @@ calls, to invoke certain actions and to report certain conditions. These are: RXRPC_LOCAL_ERROR -rt error num Local error encountered RXRPC_NEW_CALL -r- n/a New call received RXRPC_ACCEPT s-- n/a Accept new call + RXRPC_EXCLUSIVE_CALL s-- n/a Make an exclusive client call + RXRPC_UPGRADE_SERVICE s-- n/a Client call can be upgraded + RXRPC_TX_LENGTH s-- data len Total length of Tx data (SRT = usable in Sendmsg / delivered by Recvmsg / Terminal message) @@ -387,6 +390,40 @@ calls, to invoke certain actions and to report certain conditions. These are: return error ENODATA. If the user ID is already in use by another call, then error EBADSLT will be returned. + (*) RXRPC_EXCLUSIVE_CALL + + This is used to indicate that a client call should be made on a one-off + connection. The connection is discarded once the call has terminated. + + (*) RXRPC_UPGRADE_SERVICE + + This is used to make a client call to probe if the specified service ID + may be upgraded by the server. The caller must check msg_name returned to + recvmsg() for the service ID actually in use. The operation probed must + be one that takes the same arguments in both services. + + Once this has been used to establish the upgrade capability (or lack + thereof) of the server, the service ID returned should be used for all + future communication to that server and RXRPC_UPGRADE_SERVICE should no + longer be set. + + (*) RXRPC_TX_LENGTH + + This is used to inform the kernel of the total amount of data that is + going to be transmitted by a call (whether in a client request or a + service response). If given, it allows the kernel to encrypt from the + userspace buffer directly to the packet buffers, rather than copying into + the buffer and then encrypting in place. This may only be given with the + first sendmsg() providing data for a call. EMSGSIZE will be generated if + the amount of data actually given is different. + + This takes a parameter of __s64 type that indicates how much will be + transmitted. This may not be less than zero. + +The symbol RXRPC__SUPPORTED is defined as one more than the highest control +message type supported. At run time this can be queried by means of the +RXRPC_SUPPORTED_CMSG socket option (see below). + ============== SOCKET OPTIONS @@ -433,6 +470,18 @@ AF_RXRPC sockets support a few socket options at the SOL_RXRPC level: Encrypted checksum plus entire packet padded and encrypted, including actual packet length. + (*) RXRPC_UPGRADEABLE_SERVICE + + This is used to indicate that a service socket with two bindings may + upgrade one bound service to the other if requested by the client. optval + must point to an array of two unsigned short ints. The first is the + service ID to upgrade from and the second the service ID to upgrade to. + + (*) RXRPC_SUPPORTED_CMSG + + This is a read-only option that writes an int into the buffer indicating + the highest control message type supported. + ======== SECURITY @@ -542,6 +591,9 @@ A client would issue an operation by: MSG_MORE should be set in msghdr::msg_flags on all but the last part of the request. Multiple requests may be made simultaneously. + An RXRPC_TX_LENGTH control message can also be specified on the first + sendmsg() call. + If a call is intended to go to a destination other than the default specified through connect(), then msghdr::msg_name should be set on the first request message of that call. @@ -559,6 +611,17 @@ A client would issue an operation by: buffer instead, and MSG_EOR will be flagged to indicate the end of that call. +A client may ask for a service ID it knows and ask that this be upgraded to a +better service if one is available by supplying RXRPC_UPGRADE_SERVICE on the +first sendmsg() of a call. The client should then check srx_service in the +msg_name filled in by recvmsg() when collecting the result. srx_service will +hold the same value as given to sendmsg() if the upgrade request was ignored by +the service - otherwise it will be altered to indicate the service ID the +server upgraded to. Note that the upgraded service ID is chosen by the server. +The caller has to wait until it sees the service ID in the reply before sending +any more calls (further calls to the same destination will be blocked until the +probe is concluded). + ==================== EXAMPLE SERVER USAGE @@ -588,7 +651,7 @@ A server would be set up to accept operations in the following manner: The keyring can be manipulated after it has been given to the socket. This permits the server to add more keys, replace keys, etc. whilst it is live. - (2) A local address must then be bound: + (3) A local address must then be bound: struct sockaddr_rxrpc srx = { .srx_family = AF_RXRPC, @@ -600,11 +663,26 @@ A server would be set up to accept operations in the following manner: }; bind(server, &srx, sizeof(srx)); - (3) The server is then set to listen out for incoming calls: + More than one service ID may be bound to a socket, provided the transport + parameters are the same. The limit is currently two. To do this, bind() + should be called twice. + + (4) If service upgrading is required, first two service IDs must have been + bound and then the following option must be set: + + unsigned short service_ids[2] = { from_ID, to_ID }; + setsockopt(server, SOL_RXRPC, RXRPC_UPGRADEABLE_SERVICE, + service_ids, sizeof(service_ids)); + + This will automatically upgrade connections on service from_ID to service + to_ID if they request it. This will be reflected in msg_name obtained + through recvmsg() when the request data is delivered to userspace. + + (5) The server is then set to listen out for incoming calls: listen(server, 100); - (4) The kernel notifies the server of pending incoming connections by sending + (6) The kernel notifies the server of pending incoming connections by sending it a message for each. This is received with recvmsg() on the server socket. It has no data, and has a single dataless control message attached: @@ -616,13 +694,13 @@ A server would be set up to accept operations in the following manner: the time it is accepted - in which case the first call still on the queue will be accepted. - (5) The server then accepts the new call by issuing a sendmsg() with two + (7) The server then accepts the new call by issuing a sendmsg() with two pieces of control data and no actual data: RXRPC_ACCEPT - indicate connection acceptance RXRPC_USER_CALL_ID - specify user ID for this call - (6) The first request data packet will then be posted to the server socket for + (8) The first request data packet will then be posted to the server socket for recvmsg() to pick up. At that point, the RxRPC address for the call can be read from the address fields in the msghdr struct. @@ -634,7 +712,7 @@ A server would be set up to accept operations in the following manner: RXRPC_USER_CALL_ID - specifies the user ID for this call - (8) The reply data should then be posted to the server socket using a series + (9) The reply data should then be posted to the server socket using a series of sendmsg() calls, each with the following control messages attached: RXRPC_USER_CALL_ID - specifies the user ID for this call @@ -642,7 +720,7 @@ A server would be set up to accept operations in the following manner: MSG_MORE should be set in msghdr::msg_flags on all but the last message for a particular call. - (9) The final ACK from the client will be posted for retrieval by recvmsg() +(10) The final ACK from the client will be posted for retrieval by recvmsg() when it is received. It will take the form of a dataless message with two control messages attached: @@ -652,7 +730,7 @@ A server would be set up to accept operations in the following manner: MSG_EOR will be flagged to indicate that this is the final message for this call. -(10) Up to the point the final packet of reply data is sent, the call can be +(11) Up to the point the final packet of reply data is sent, the call can be aborted by calling sendmsg() with a dataless message with the following control messages attached: @@ -703,6 +781,7 @@ The kernel interface functions are as follows: struct sockaddr_rxrpc *srx, struct key *key, unsigned long user_call_ID, + s64 tx_total_len, gfp_t gfp); This allocates the infrastructure to make a new RxRPC call and assigns @@ -719,6 +798,11 @@ The kernel interface functions are as follows: control data buffer. It is entirely feasible to use this to point to a kernel data structure. + tx_total_len is the amount of data the caller is intending to transmit + with this call (or -1 if unknown at this point). Setting the data size + allows the kernel to encrypt directly to the packet buffers, thereby + saving a copy. The value may not be less than -1. + If this function is successful, an opaque reference to the RxRPC call is returned. The caller now holds a reference on this and it must be properly ended. @@ -870,6 +954,17 @@ The kernel interface functions are as follows: This is used to find the remote peer address of a call. + (*) Set the total transmit data size on a call. + + void rxrpc_kernel_set_tx_length(struct socket *sock, + struct rxrpc_call *call, + s64 tx_total_len); + + This sets the amount of data that the caller is intending to transmit on a + call. It's intended to be used for setting the reply size as the request + size should be set when the call is begun. tx_total_len may not be less + than zero. + ======================= CONFIGURABLE PARAMETERS diff --git a/Documentation/networking/scaling.txt b/Documentation/networking/scaling.txt index 59f4db2a0c85..f55639d71d35 100644 --- a/Documentation/networking/scaling.txt +++ b/Documentation/networking/scaling.txt @@ -122,7 +122,7 @@ associated flow of the packet. The hash is either provided by hardware or will be computed in the stack. Capable hardware can pass the hash in the receive descriptor for the packet; this would usually be the same hash used for RSS (e.g. computed Toeplitz hash). The hash is saved in -skb->rx_hash and can be used elsewhere in the stack as a hash of the +skb->hash and can be used elsewhere in the stack as a hash of the packet’s flow. Each receive hardware queue has an associated list of CPUs to which diff --git a/Documentation/networking/tcp.txt b/Documentation/networking/tcp.txt index bdc4c0db51e1..9c7139d57e57 100644 --- a/Documentation/networking/tcp.txt +++ b/Documentation/networking/tcp.txt @@ -1,7 +1,7 @@ TCP protocol ============ -Last updated: 9 February 2008 +Last updated: 3 June 2017 Contents ======== @@ -29,18 +29,19 @@ As of 2.6.13, Linux supports pluggable congestion control algorithms. A congestion control mechanism can be registered through functions in tcp_cong.c. The functions used by the congestion control mechanism are registered via passing a tcp_congestion_ops struct to -tcp_register_congestion_control. As a minimum name, ssthresh, -cong_avoid must be valid. +tcp_register_congestion_control. As a minimum, the congestion control +mechanism must provide a valid name and must implement either ssthresh, +cong_avoid and undo_cwnd hooks or the "omnipotent" cong_control hook. Private data for a congestion control mechanism is stored in tp->ca_priv. tcp_ca(tp) returns a pointer to this space. This is preallocated space - it is important to check the size of your private data will fit this space, or -alternatively space could be allocated elsewhere and a pointer to it could +alternatively, space could be allocated elsewhere and a pointer to it could be stored here. There are three kinds of congestion control algorithms currently: The simplest ones are derived from TCP reno (highspeed, scalable) and just -provide an alternative the congestion window calculation. More complex +provide an alternative congestion window calculation. More complex ones like BIC try to look at other events to provide better heuristics. There are also round trip time based algorithms like Vegas and Westwood+. @@ -49,21 +50,15 @@ Good TCP congestion control is a complex problem because the algorithm needs to maintain fairness and performance. Please review current research and RFC's before developing new modules. -The method that is used to determine which congestion control mechanism is -determined by the setting of the sysctl net.ipv4.tcp_congestion_control. -The default congestion control will be the last one registered (LIFO); -so if you built everything as modules, the default will be reno. If you -build with the defaults from Kconfig, then CUBIC will be builtin (not a -module) and it will end up the default. +The default congestion control mechanism is chosen based on the +DEFAULT_TCP_CONG Kconfig parameter. If you really want a particular default +value then you can set it using sysctl net.ipv4.tcp_congestion_control. The +module will be autoloaded if needed and you will get the expected protocol. If +you ask for an unknown congestion method, then the sysctl attempt will fail. -If you really want a particular default value then you will need -to set it with the sysctl. If you use a sysctl, the module will be autoloaded -if needed and you will get the expected protocol. If you ask for an -unknown congestion method, then the sysctl attempt will fail. - -If you remove a tcp congestion control module, then you will get the next +If you remove a TCP congestion control module, then you will get the next available one. Since reno cannot be built as a module, and cannot be -deleted, it will always be available. +removed, it will always be available. How the new TCP output machine [nyi] works. =========================================== diff --git a/Documentation/networking/timestamping.txt b/Documentation/networking/timestamping.txt index 96f50694a748..196ba17cc344 100644 --- a/Documentation/networking/timestamping.txt +++ b/Documentation/networking/timestamping.txt @@ -193,6 +193,24 @@ SOF_TIMESTAMPING_OPT_STATS: the transmit timestamps, such as how long a certain block of data was limited by peer's receiver window. +SOF_TIMESTAMPING_OPT_PKTINFO: + + Enable the SCM_TIMESTAMPING_PKTINFO control message for incoming + packets with hardware timestamps. The message contains struct + scm_ts_pktinfo, which supplies the index of the real interface which + received the packet and its length at layer 2. A valid (non-zero) + interface index will be returned only if CONFIG_NET_RX_BUSY_POLL is + enabled and the driver is using NAPI. The struct contains also two + other fields, but they are reserved and undefined. + +SOF_TIMESTAMPING_OPT_TX_SWHW: + + Request both hardware and software timestamps for outgoing packets + when SOF_TIMESTAMPING_TX_HARDWARE and SOF_TIMESTAMPING_TX_SOFTWARE + are enabled at the same time. If both timestamps are generated, + two separate messages will be looped to the socket's error queue, + each containing just one timestamp. + New applications are encouraged to pass SOF_TIMESTAMPING_OPT_ID to disambiguate timestamps and SOF_TIMESTAMPING_OPT_TSONLY to operate regardless of the setting of sysctl net.core.tstamp_allow_data. @@ -312,7 +330,7 @@ struct scm_timestamping { }; The structure can return up to three timestamps. This is a legacy -feature. Only one field is non-zero at any time. Most timestamps +feature. At least one field is non-zero at any time. Most timestamps are passed in ts[0]. Hardware timestamps are passed in ts[2]. ts[1] used to hold hardware timestamps converted to system time. @@ -321,6 +339,12 @@ a HW PTP clock source, to allow time conversion in userspace and optionally synchronize system time with a userspace PTP stack such as linuxptp. For the PTP clock API, see Documentation/ptp/ptp.txt. +Note that if the SO_TIMESTAMP or SO_TIMESTAMPNS option is enabled +together with SO_TIMESTAMPING using SOF_TIMESTAMPING_SOFTWARE, a false +software timestamp will be generated in the recvmsg() call and passed +in ts[0] when a real software timestamp is missing. This happens also +on hardware transmit timestamps. + 2.1.1 Transmit timestamps with MSG_ERRQUEUE For transmit timestamps the outgoing packet is looped back to the diff --git a/Documentation/networking/tls.txt b/Documentation/networking/tls.txt new file mode 100644 index 000000000000..77ed00631c12 --- /dev/null +++ b/Documentation/networking/tls.txt @@ -0,0 +1,135 @@ +Overview +======== + +Transport Layer Security (TLS) is a Upper Layer Protocol (ULP) that runs over +TCP. TLS provides end-to-end data integrity and confidentiality. + +User interface +============== + +Creating a TLS connection +------------------------- + +First create a new TCP socket and set the TLS ULP. + + sock = socket(AF_INET, SOCK_STREAM, 0); + setsockopt(sock, SOL_TCP, TCP_ULP, "tls", sizeof("tls")); + +Setting the TLS ULP allows us to set/get TLS socket options. Currently +only the symmetric encryption is handled in the kernel. After the TLS +handshake is complete, we have all the parameters required to move the +data-path to the kernel. There is a separate socket option for moving +the transmit and the receive into the kernel. + + /* From linux/tls.h */ + struct tls_crypto_info { + unsigned short version; + unsigned short cipher_type; + }; + + struct tls12_crypto_info_aes_gcm_128 { + struct tls_crypto_info info; + unsigned char iv[TLS_CIPHER_AES_GCM_128_IV_SIZE]; + unsigned char key[TLS_CIPHER_AES_GCM_128_KEY_SIZE]; + unsigned char salt[TLS_CIPHER_AES_GCM_128_SALT_SIZE]; + unsigned char rec_seq[TLS_CIPHER_AES_GCM_128_REC_SEQ_SIZE]; + }; + + + struct tls12_crypto_info_aes_gcm_128 crypto_info; + + crypto_info.info.version = TLS_1_2_VERSION; + crypto_info.info.cipher_type = TLS_CIPHER_AES_GCM_128; + memcpy(crypto_info.iv, iv_write, TLS_CIPHER_AES_GCM_128_IV_SIZE); + memcpy(crypto_info.rec_seq, seq_number_write, + TLS_CIPHER_AES_GCM_128_REC_SEQ_SIZE); + memcpy(crypto_info.key, cipher_key_write, TLS_CIPHER_AES_GCM_128_KEY_SIZE); + memcpy(crypto_info.salt, implicit_iv_write, TLS_CIPHER_AES_GCM_128_SALT_SIZE); + + setsockopt(sock, SOL_TLS, TLS_TX, &crypto_info, sizeof(crypto_info)); + +Sending TLS application data +---------------------------- + +After setting the TLS_TX socket option all application data sent over this +socket is encrypted using TLS and the parameters provided in the socket option. +For example, we can send an encrypted hello world record as follows: + + const char *msg = "hello world\n"; + send(sock, msg, strlen(msg)); + +send() data is directly encrypted from the userspace buffer provided +to the encrypted kernel send buffer if possible. + +The sendfile system call will send the file's data over TLS records of maximum +length (2^14). + + file = open(filename, O_RDONLY); + fstat(file, &stat); + sendfile(sock, file, &offset, stat.st_size); + +TLS records are created and sent after each send() call, unless +MSG_MORE is passed. MSG_MORE will delay creation of a record until +MSG_MORE is not passed, or the maximum record size is reached. + +The kernel will need to allocate a buffer for the encrypted data. +This buffer is allocated at the time send() is called, such that +either the entire send() call will return -ENOMEM (or block waiting +for memory), or the encryption will always succeed. If send() returns +-ENOMEM and some data was left on the socket buffer from a previous +call using MSG_MORE, the MSG_MORE data is left on the socket buffer. + +Send TLS control messages +------------------------- + +Other than application data, TLS has control messages such as alert +messages (record type 21) and handshake messages (record type 22), etc. +These messages can be sent over the socket by providing the TLS record type +via a CMSG. For example the following function sends @data of @length bytes +using a record of type @record_type. + +/* send TLS control message using record_type */ + static int klts_send_ctrl_message(int sock, unsigned char record_type, + void *data, size_t length) + { + struct msghdr msg = {0}; + int cmsg_len = sizeof(record_type); + struct cmsghdr *cmsg; + char buf[CMSG_SPACE(cmsg_len)]; + struct iovec msg_iov; /* Vector of data to send/receive into. */ + + msg.msg_control = buf; + msg.msg_controllen = sizeof(buf); + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_TLS; + cmsg->cmsg_type = TLS_SET_RECORD_TYPE; + cmsg->cmsg_len = CMSG_LEN(cmsg_len); + *CMSG_DATA(cmsg) = record_type; + msg.msg_controllen = cmsg->cmsg_len; + + msg_iov.iov_base = data; + msg_iov.iov_len = length; + msg.msg_iov = &msg_iov; + msg.msg_iovlen = 1; + + return sendmsg(sock, &msg, 0); + } + +Control message data should be provided unencrypted, and will be +encrypted by the kernel. + +Integrating in to userspace TLS library +--------------------------------------- + +At a high level, the kernel TLS ULP is a replacement for the record +layer of a userspace TLS library. + +A patchset to OpenSSL to use ktls as the record layer is here: + +https://github.com/Mellanox/tls-openssl + +An example of calling send directly after a handshake using +gnutls. Since it doesn't implement a full record layer, control +messages are not supported: + +https://github.com/Mellanox/tls-af_ktls_tool diff --git a/Documentation/networking/z8530book.rst b/Documentation/networking/z8530book.rst new file mode 100644 index 000000000000..fea2c40e7973 --- /dev/null +++ b/Documentation/networking/z8530book.rst @@ -0,0 +1,256 @@ +======================= +Z8530 Programming Guide +======================= + +:Author: Alan Cox + +Introduction +============ + +The Z85x30 family synchronous/asynchronous controller chips are used on +a large number of cheap network interface cards. The kernel provides a +core interface layer that is designed to make it easy to provide WAN +services using this chip. + +The current driver only support synchronous operation. Merging the +asynchronous driver support into this code to allow any Z85x30 device to +be used as both a tty interface and as a synchronous controller is a +project for Linux post the 2.4 release + +Driver Modes +============ + +The Z85230 driver layer can drive Z8530, Z85C30 and Z85230 devices in +three different modes. Each mode can be applied to an individual channel +on the chip (each chip has two channels). + +The PIO synchronous mode supports the most common Z8530 wiring. Here the +chip is interface to the I/O and interrupt facilities of the host +machine but not to the DMA subsystem. When running PIO the Z8530 has +extremely tight timing requirements. Doing high speeds, even with a +Z85230 will be tricky. Typically you should expect to achieve at best +9600 baud with a Z8C530 and 64Kbits with a Z85230. + +The DMA mode supports the chip when it is configured to use dual DMA +channels on an ISA bus. The better cards tend to support this mode of +operation for a single channel. With DMA running the Z85230 tops out +when it starts to hit ISA DMA constraints at about 512Kbits. It is worth +noting here that many PC machines hang or crash when the chip is driven +fast enough to hold the ISA bus solid. + +Transmit DMA mode uses a single DMA channel. The DMA channel is used for +transmission as the transmit FIFO is smaller than the receive FIFO. it +gives better performance than pure PIO mode but is nowhere near as ideal +as pure DMA mode. + +Using the Z85230 driver +======================= + +The Z85230 driver provides the back end interface to your board. To +configure a Z8530 interface you need to detect the board and to identify +its ports and interrupt resources. It is also your problem to verify the +resources are available. + +Having identified the chip you need to fill in a struct z8530_dev, +which describes each chip. This object must exist until you finally +shutdown the board. Firstly zero the active field. This ensures nothing +goes off without you intending it. The irq field should be set to the +interrupt number of the chip. (Each chip has a single interrupt source +rather than each channel). You are responsible for allocating the +interrupt line. The interrupt handler should be set to +:c:func:`z8530_interrupt()`. The device id should be set to the +z8530_dev structure pointer. Whether the interrupt can be shared or not +is board dependent, and up to you to initialise. + +The structure holds two channel structures. Initialise chanA.ctrlio and +chanA.dataio with the address of the control and data ports. You can or +this with Z8530_PORT_SLEEP to indicate your interface needs the 5uS +delay for chip settling done in software. The PORT_SLEEP option is +architecture specific. Other flags may become available on future +platforms, eg for MMIO. Initialise the chanA.irqs to &z8530_nop to +start the chip up as disabled and discarding interrupt events. This +ensures that stray interrupts will be mopped up and not hang the bus. +Set chanA.dev to point to the device structure itself. The private and +name field you may use as you wish. The private field is unused by the +Z85230 layer. The name is used for error reporting and it may thus make +sense to make it match the network name. + +Repeat the same operation with the B channel if your chip has both +channels wired to something useful. This isn't always the case. If it is +not wired then the I/O values do not matter, but you must initialise +chanB.dev. + +If your board has DMA facilities then initialise the txdma and rxdma +fields for the relevant channels. You must also allocate the ISA DMA +channels and do any necessary board level initialisation to configure +them. The low level driver will do the Z8530 and DMA controller +programming but not board specific magic. + +Having initialised the device you can then call +:c:func:`z8530_init()`. This will probe the chip and reset it into +a known state. An identification sequence is then run to identify the +chip type. If the checks fail to pass the function returns a non zero +error code. Typically this indicates that the port given is not valid. +After this call the type field of the z8530_dev structure is +initialised to either Z8530, Z85C30 or Z85230 according to the chip +found. + +Once you have called z8530_init you can also make use of the utility +function :c:func:`z8530_describe()`. This provides a consistent +reporting format for the Z8530 devices, and allows all the drivers to +provide consistent reporting. + +Attaching Network Interfaces +============================ + +If you wish to use the network interface facilities of the driver, then +you need to attach a network device to each channel that is present and +in use. In addition to use the generic HDLC you need to follow some +additional plumbing rules. They may seem complex but a look at the +example hostess_sv11 driver should reassure you. + +The network device used for each channel should be pointed to by the +netdevice field of each channel. The hdlc-> priv field of the network +device points to your private data - you will need to be able to find +your private data from this. + +The way most drivers approach this particular problem is to create a +structure holding the Z8530 device definition and put that into the +private field of the network device. The network device fields of the +channels then point back to the network devices. + +If you wish to use the generic HDLC then you need to register the HDLC +device. + +Before you register your network device you will also need to provide +suitable handlers for most of the network device callbacks. See the +network device documentation for more details on this. + +Configuring And Activating The Port +=================================== + +The Z85230 driver provides helper functions and tables to load the port +registers on the Z8530 chips. When programming the register settings for +a channel be aware that the documentation recommends initialisation +orders. Strange things happen when these are not followed. + +:c:func:`z8530_channel_load()` takes an array of pairs of +initialisation values in an array of u8 type. The first value is the +Z8530 register number. Add 16 to indicate the alternate register bank on +the later chips. The array is terminated by a 255. + +The driver provides a pair of public tables. The z8530_hdlc_kilostream +table is for the UK 'Kilostream' service and also happens to cover most +other end host configurations. The z8530_hdlc_kilostream_85230 table +is the same configuration using the enhancements of the 85230 chip. The +configuration loaded is standard NRZ encoded synchronous data with HDLC +bitstuffing. All of the timing is taken from the other end of the link. + +When writing your own tables be aware that the driver internally tracks +register values. It may need to reload values. You should therefore be +sure to set registers 1-7, 9-11, 14 and 15 in all configurations. Where +the register settings depend on DMA selection the driver will update the +bits itself when you open or close. Loading a new table with the +interface open is not recommended. + +There are three standard configurations supported by the core code. In +PIO mode the interface is programmed up to use interrupt driven PIO. +This places high demands on the host processor to avoid latency. The +driver is written to take account of latency issues but it cannot avoid +latencies caused by other drivers, notably IDE in PIO mode. Because the +drivers allocate buffers you must also prevent MTU changes while the +port is open. + +Once the port is open it will call the rx_function of each channel +whenever a completed packet arrived. This is invoked from interrupt +context and passes you the channel and a network buffer (struct +sk_buff) holding the data. The data includes the CRC bytes so most +users will want to trim the last two bytes before processing the data. +This function is very timing critical. When you wish to simply discard +data the support code provides the function +:c:func:`z8530_null_rx()` to discard the data. + +To active PIO mode sending and receiving the ``z8530_sync_open`` is called. +This expects to be passed the network device and the channel. Typically +this is called from your network device open callback. On a failure a +non zero error status is returned. +The :c:func:`z8530_sync_close()` function shuts down a PIO +channel. This must be done before the channel is opened again and before +the driver shuts down and unloads. + +The ideal mode of operation is dual channel DMA mode. Here the kernel +driver will configure the board for DMA in both directions. The driver +also handles ISA DMA issues such as controller programming and the +memory range limit for you. This mode is activated by calling the +:c:func:`z8530_sync_dma_open()` function. On failure a non zero +error value is returned. Once this mode is activated it can be shut down +by calling the :c:func:`z8530_sync_dma_close()`. You must call +the close function matching the open mode you used. + +The final supported mode uses a single DMA channel to drive the transmit +side. As the Z85C30 has a larger FIFO on the receive channel this tends +to increase the maximum speed a little. This is activated by calling the +``z8530_sync_txdma_open``. This returns a non zero error code on failure. The +:c:func:`z8530_sync_txdma_close()` function closes down the Z8530 +interface from this mode. + +Network Layer Functions +======================= + +The Z8530 layer provides functions to queue packets for transmission. +The driver internally buffers the frame currently being transmitted and +one further frame (in order to keep back to back transmission running). +Any further buffering is up to the caller. + +The function :c:func:`z8530_queue_xmit()` takes a network buffer +in sk_buff format and queues it for transmission. The caller must +provide the entire packet with the exception of the bitstuffing and CRC. +This is normally done by the caller via the generic HDLC interface +layer. It returns 0 if the buffer has been queued and non zero values +for queue full. If the function accepts the buffer it becomes property +of the Z8530 layer and the caller should not free it. + +The function :c:func:`z8530_get_stats()` returns a pointer to an +internally maintained per interface statistics block. This provides most +of the interface code needed to implement the network layer get_stats +callback. + +Porting The Z8530 Driver +======================== + +The Z8530 driver is written to be portable. In DMA mode it makes +assumptions about the use of ISA DMA. These are probably warranted in +most cases as the Z85230 in particular was designed to glue to PC type +machines. The PIO mode makes no real assumptions. + +Should you need to retarget the Z8530 driver to another architecture the +only code that should need changing are the port I/O functions. At the +moment these assume PC I/O port accesses. This may not be appropriate +for all platforms. Replacing :c:func:`z8530_read_port()` and +``z8530_write_port`` is intended to be all that is required to port +this driver layer. + +Known Bugs And Assumptions +========================== + +Interrupt Locking + The locking in the driver is done via the global cli/sti lock. This + makes for relatively poor SMP performance. Switching this to use a + per device spin lock would probably materially improve performance. + +Occasional Failures + We have reports of occasional failures when run for very long + periods of time and the driver starts to receive junk frames. At the + moment the cause of this is not clear. + +Public Functions Provided +========================= + +.. kernel-doc:: drivers/net/wan/z85230.c + :export: + +Internal Functions +================== + +.. kernel-doc:: drivers/net/wan/z85230.c + :internal: diff --git a/Documentation/power/power_supply_class.txt b/Documentation/power/power_supply_class.txt index 0c72588bd967..300d37896e51 100644 --- a/Documentation/power/power_supply_class.txt +++ b/Documentation/power/power_supply_class.txt @@ -115,28 +115,33 @@ of charge when battery became full/empty". It also could mean "value of charge when battery considered full/empty at given conditions (temperature, age)". I.e. these attributes represents real thresholds, not design values. +ENERGY_FULL, ENERGY_EMPTY - same as above but for energy. + CHARGE_COUNTER - the current charge counter (in µAh). This could easily be negative; there is no empty or full value. It is only useful for relative, time-based measurements. +PRECHARGE_CURRENT - the maximum charge current during precharge phase +of charge cycle (typically 20% of battery capacity). +CHARGE_TERM_CURRENT - Charge termination current. The charge cycle +terminates when battery voltage is above recharge threshold, and charge +current is below this setting (typically 10% of battery capacity). + CONSTANT_CHARGE_CURRENT - constant charge current programmed by charger. CONSTANT_CHARGE_CURRENT_MAX - maximum charge current supported by the power supply object. -INPUT_CURRENT_LIMIT - input current limit programmed by charger. Indicates -the current drawn from a charging source. -CHARGE_TERM_CURRENT - Charge termination current used to detect the end of charge -condition. - -CALIBRATE - battery or coulomb counter calibration status CONSTANT_CHARGE_VOLTAGE - constant charge voltage programmed by charger. CONSTANT_CHARGE_VOLTAGE_MAX - maximum charge voltage supported by the power supply object. +INPUT_CURRENT_LIMIT - input current limit programmed by charger. Indicates +the current drawn from a charging source. + CHARGE_CONTROL_LIMIT - current charge control limit setting CHARGE_CONTROL_LIMIT_MAX - maximum charge control limit setting -ENERGY_FULL, ENERGY_EMPTY - same as above but for energy. +CALIBRATE - battery or coulomb counter calibration status CAPACITY - capacity in percents. CAPACITY_ALERT_MIN - minimum capacity alert value in percents. @@ -174,6 +179,18 @@ issued by external power supply will notify supplicants via external_power_changed callback. +Devicetree battery characteristics +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Drivers should call power_supply_get_battery_info() to obtain battery +characteristics from a devicetree battery node, defined in +Documentation/devicetree/bindings/power/supply/battery.txt. This is +implemented in drivers/power/supply/bq27xxx_battery.c. + +Properties in struct power_supply_battery_info and their counterparts in the +battery node have names corresponding to elements in enum power_supply_property, +for naming consistency between sysfs attributes and battery node properties. + + QA ~~ Q: Where is POWER_SUPPLY_PROP_XYZ attribute? diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt index ee69d7532172..0fde3dcf077a 100644 --- a/Documentation/power/runtime_pm.txt +++ b/Documentation/power/runtime_pm.txt @@ -105,9 +105,9 @@ knows what to do to handle the device). In particular, if the driver requires remote wakeup capability (i.e. hardware mechanism allowing the device to request a change of its power state, such as -PCI PME) for proper functioning and device_run_wake() returns 'false' for the +PCI PME) for proper functioning and device_can_wakeup() returns 'false' for the device, then ->runtime_suspend() should return -EBUSY. On the other hand, if -device_run_wake() returns 'true' for the device and the device is put into a +device_can_wakeup() returns 'true' for the device and the device is put into a low-power state during the execution of the suspend callback, it is expected that remote wakeup will be enabled for the device. Generally, remote wakeup should be enabled for all input devices put into low-power states at run time. @@ -253,9 +253,6 @@ defined in include/linux/pm.h: being executed for that device and it is not practical to wait for the suspend to complete; means "start a resume as soon as you've suspended" - unsigned int run_wake; - - set if the device is capable of generating runtime wake-up events - enum rpm_status runtime_status; - the runtime PM status of the device; this field's initial value is RPM_SUSPENDED, which means that each device is initially regarded by the diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst index e25d63f8c0da..3aed751e0cb5 100644 --- a/Documentation/process/changes.rst +++ b/Documentation/process/changes.rst @@ -116,12 +116,11 @@ DevFS has been obsoleted in favour of udev Linux documentation for functions is transitioning to inline documentation via specially-formatted comments near their -definitions in the source. These comments can be combined with the -SGML templates in the Documentation/DocBook directory to make DocBook -files, which can then be converted by DocBook stylesheets to PostScript, -HTML, PDF files, and several other formats. In order to convert from -DocBook format to a format of your choice, you'll need to install Jade as -well as the desired DocBook stylesheets. +definitions in the source. These comments can be combined with ReST +files the Documentation/ directory to make enriched documentation, which can +then be converted to PostScript, HTML, LaTex, ePUB and PDF files. +In order to convert from ReST format to a format of your choice, you'll need +Sphinx. Util-linux ---------- @@ -323,12 +322,6 @@ PDF outputs, it is recommended to use version 1.4.6. functionalities required for ``XeLaTex`` to work. For PDF output you'll also need ``convert(1)`` from ImageMagick (https://www.imagemagick.org). -Other tools ------------ - -In order to produce documentation from DocBook, you'll also need ``xmlto``. -Please notice, however, that we're currently migrating all documents to use -``Sphinx``. Getting updated software ======================== @@ -409,15 +402,6 @@ Quota-tools - <http://sourceforge.net/projects/linuxquota/> -DocBook Stylesheets -------------------- - -- <http://sourceforge.net/projects/docbook/files/docbook-dsssl/> - -XMLTO XSLT Frontend -------------------- - -- <http://cyberelk.net/tim/xmlto/> Intel P6 microcode ------------------ diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst index d20d52a4d812..a20b44a40ec4 100644 --- a/Documentation/process/coding-style.rst +++ b/Documentation/process/coding-style.rst @@ -980,8 +980,8 @@ do so, though, and doing so unnecessarily can limit optimization. When writing a single inline assembly statement containing multiple instructions, put each instruction on a separate line in a separate quoted -string, and end each string except the last with \n\t to properly indent the -next instruction in the assembly output: +string, and end each string except the last with ``\n\t`` to properly indent +the next instruction in the assembly output: .. code-block:: c diff --git a/Documentation/process/email-clients.rst b/Documentation/process/email-clients.rst index ac892b30815e..07faa5457bcb 100644 --- a/Documentation/process/email-clients.rst +++ b/Documentation/process/email-clients.rst @@ -167,6 +167,11 @@ Lotus Notes (GUI) Run away from it. +IBM Verse (Web GUI) +******************* + +See Lotus Notes. + Mutt (TUI) ********** diff --git a/Documentation/process/howto.rst b/Documentation/process/howto.rst index 1260f60d4cb9..c6875b1db56f 100644 --- a/Documentation/process/howto.rst +++ b/Documentation/process/howto.rst @@ -180,14 +180,6 @@ They can also be generated on LaTeX and ePub formats with:: make latexdocs make epubdocs -Currently, there are some documents written on DocBook that are in -the process of conversion to ReST. Such documents will be created in the -Documentation/DocBook/ directory and can be generated also as -Postscript or man pages by running:: - - make psdocs - make mandocs - Becoming A Kernel Developer --------------------------- diff --git a/Documentation/process/kernel-docs.rst b/Documentation/process/kernel-docs.rst index 05a7857a4a83..b8cac85a4001 100644 --- a/Documentation/process/kernel-docs.rst +++ b/Documentation/process/kernel-docs.rst @@ -40,50 +40,18 @@ Enjoy! Docs at the Linux Kernel tree ----------------------------- -The DocBook books should be built with ``make {htmldocs | psdocs | pdfdocs}``. The Sphinx books should be built with ``make {htmldocs | pdfdocs | epubdocs}``. * Name: **linux/Documentation** :Author: Many. :Location: Documentation/ - :Keywords: text files, Sphinx, DocBook. + :Keywords: text files, Sphinx. :Description: Documentation that comes with the kernel sources, inside the Documentation directory. Some pages from this document (including this document itself) have been moved there, and might be more up to date than the web version. - * Title: **The Kernel Hacking HOWTO** - - :Author: Various Talented People, and Rusty. - :Location: Documentation/DocBook/kernel-hacking.tmpl - :Keywords: HOWTO, kernel contexts, deadlock, locking, modules, - symbols, return conventions. - :Description: From the Introduction: "Please understand that I - never wanted to write this document, being grossly underqualified, - but I always wanted to read it, and this was the only way. I - simply explain some best practices, and give reading entry-points - into the kernel sources. I avoid implementation details: that's - what the code is for, and I ignore whole tracts of useful - routines. This document assumes familiarity with C, and an - understanding of what the kernel is, and how it is used. It was - originally written for the 2.3 kernels, but nearly all of it - applies to 2.2 too; 2.0 is slightly different". - - * Title: **Linux Kernel Locking HOWTO** - - :Author: Various Talented People, and Rusty. - :Location: Documentation/DocBook/kernel-locking.tmpl - :Keywords: locks, locking, spinlock, semaphore, atomic, race - condition, bottom halves, tasklets, softirqs. - :Description: The title says it all: document describing the - locking system in the Linux Kernel either in uniprocessor or SMP - systems. - :Notes: "It was originally written for the later (>2.3.47) 2.3 - kernels, but most of it applies to 2.2 too; 2.0 is slightly - different". Freely redistributable under the conditions of the GNU - General Public License. - On-line docs ------------ diff --git a/Documentation/scheduler/sched-deadline.txt b/Documentation/scheduler/sched-deadline.txt index cbc1b46cbf70..e89e36ec15a5 100644 --- a/Documentation/scheduler/sched-deadline.txt +++ b/Documentation/scheduler/sched-deadline.txt @@ -7,6 +7,8 @@ CONTENTS 0. WARNING 1. Overview 2. Scheduling algorithm + 2.1 Main algorithm + 2.2 Bandwidth reclaiming 3. Scheduling Real-Time Tasks 3.1 Definitions 3.2 Schedulability Analysis for Uniprocessor Systems @@ -44,6 +46,9 @@ CONTENTS 2. Scheduling algorithm ================== +2.1 Main algorithm +------------------ + SCHED_DEADLINE uses three parameters, named "runtime", "period", and "deadline", to schedule tasks. A SCHED_DEADLINE task should receive "runtime" microseconds of execution time every "period" microseconds, and @@ -113,6 +118,160 @@ CONTENTS remaining runtime = remaining runtime + runtime +2.2 Bandwidth reclaiming +------------------------ + + Bandwidth reclaiming for deadline tasks is based on the GRUB (Greedy + Reclamation of Unused Bandwidth) algorithm [15, 16, 17] and it is enabled + when flag SCHED_FLAG_RECLAIM is set. + + The following diagram illustrates the state names for tasks handled by GRUB: + + ------------ + (d) | Active | + ------------->| | + | | Contending | + | ------------ + | A | + ---------- | | + | | | | + | Inactive | |(b) | (a) + | | | | + ---------- | | + A | V + | ------------ + | | Active | + --------------| Non | + (c) | Contending | + ------------ + + A task can be in one of the following states: + + - ActiveContending: if it is ready for execution (or executing); + + - ActiveNonContending: if it just blocked and has not yet surpassed the 0-lag + time; + + - Inactive: if it is blocked and has surpassed the 0-lag time. + + State transitions: + + (a) When a task blocks, it does not become immediately inactive since its + bandwidth cannot be immediately reclaimed without breaking the + real-time guarantees. It therefore enters a transitional state called + ActiveNonContending. The scheduler arms the "inactive timer" to fire at + the 0-lag time, when the task's bandwidth can be reclaimed without + breaking the real-time guarantees. + + The 0-lag time for a task entering the ActiveNonContending state is + computed as + + (runtime * dl_period) + deadline - --------------------- + dl_runtime + + where runtime is the remaining runtime, while dl_runtime and dl_period + are the reservation parameters. + + (b) If the task wakes up before the inactive timer fires, the task re-enters + the ActiveContending state and the "inactive timer" is canceled. + In addition, if the task wakes up on a different runqueue, then + the task's utilization must be removed from the previous runqueue's active + utilization and must be added to the new runqueue's active utilization. + In order to avoid races between a task waking up on a runqueue while the + "inactive timer" is running on a different CPU, the "dl_non_contending" + flag is used to indicate that a task is not on a runqueue but is active + (so, the flag is set when the task blocks and is cleared when the + "inactive timer" fires or when the task wakes up). + + (c) When the "inactive timer" fires, the task enters the Inactive state and + its utilization is removed from the runqueue's active utilization. + + (d) When an inactive task wakes up, it enters the ActiveContending state and + its utilization is added to the active utilization of the runqueue where + it has been enqueued. + + For each runqueue, the algorithm GRUB keeps track of two different bandwidths: + + - Active bandwidth (running_bw): this is the sum of the bandwidths of all + tasks in active state (i.e., ActiveContending or ActiveNonContending); + + - Total bandwidth (this_bw): this is the sum of all tasks "belonging" to the + runqueue, including the tasks in Inactive state. + + + The algorithm reclaims the bandwidth of the tasks in Inactive state. + It does so by decrementing the runtime of the executing task Ti at a pace equal + to + + dq = -max{ Ui, (1 - Uinact) } dt + + where Uinact is the inactive utilization, computed as (this_bq - running_bw), + and Ui is the bandwidth of task Ti. + + + Let's now see a trivial example of two deadline tasks with runtime equal + to 4 and period equal to 8 (i.e., bandwidth equal to 0.5): + + A Task T1 + | + | | + | | + |-------- |---- + | | V + |---|---|---|---|---|---|---|---|--------->t + 0 1 2 3 4 5 6 7 8 + + + A Task T2 + | + | | + | | + | ------------------------| + | | V + |---|---|---|---|---|---|---|---|--------->t + 0 1 2 3 4 5 6 7 8 + + + A running_bw + | + 1 ----------------- ------ + | | | + 0.5- ----------------- + | | + |---|---|---|---|---|---|---|---|--------->t + 0 1 2 3 4 5 6 7 8 + + + - Time t = 0: + + Both tasks are ready for execution and therefore in ActiveContending state. + Suppose Task T1 is the first task to start execution. + Since there are no inactive tasks, its runtime is decreased as dq = -1 dt. + + - Time t = 2: + + Suppose that task T1 blocks + Task T1 therefore enters the ActiveNonContending state. Since its remaining + runtime is equal to 2, its 0-lag time is equal to t = 4. + Task T2 start execution, with runtime still decreased as dq = -1 dt since + there are no inactive tasks. + + - Time t = 4: + + This is the 0-lag time for Task T1. Since it didn't woken up in the + meantime, it enters the Inactive state. Its bandwidth is removed from + running_bw. + Task T2 continues its execution. However, its runtime is now decreased as + dq = - 0.5 dt because Uinact = 0.5. + Task T2 therefore reclaims the bandwidth unused by Task T1. + + - Time t = 8: + + Task T1 wakes up. It enters the ActiveContending state again, and the + running_bw is incremented. + + 3. Scheduling Real-Time Tasks ============================= @@ -330,6 +489,15 @@ CONTENTS 14 - J. Erickson, U. Devi and S. Baruah. Improved tardiness bounds for Global EDF. Proceedings of the 22nd Euromicro Conference on Real-Time Systems, 2010. + 15 - G. Lipari, S. Baruah, Greedy reclamation of unused bandwidth in + constant-bandwidth servers, 12th IEEE Euromicro Conference on Real-Time + Systems, 2000. + 16 - L. Abeni, J. Lelli, C. Scordino, L. Palopoli, Greedy CPU reclaiming for + SCHED DEADLINE. In Proceedings of the Real-Time Linux Workshop (RTLWS), + Dusseldorf, Germany, 2014. + 17 - L. Abeni, G. Lipari, A. Parri, Y. Sun, Multicore CPU reclaiming: parallel + or sequential?. In Proceedings of the 31st Annual ACM Symposium on Applied + Computing, 2016. 4. Bandwidth management diff --git a/Documentation/security/00-INDEX b/Documentation/security/00-INDEX deleted file mode 100644 index 45c82fd3e9d3..000000000000 --- a/Documentation/security/00-INDEX +++ /dev/null @@ -1,26 +0,0 @@ -00-INDEX - - this file. -LSM.txt - - description of the Linux Security Module framework. -SELinux.txt - - how to get started with the SELinux security enhancement. -Smack.txt - - documentation on the Smack Linux Security Module. -Yama.txt - - documentation on the Yama Linux Security Module. -apparmor.txt - - documentation on the AppArmor security extension. -credentials.txt - - documentation about credentials in Linux. -keys-ecryptfs.txt - - description of the encryption keys for the ecryptfs filesystem. -keys-request-key.txt - - description of the kernel key request service. -keys-trusted-encrypted.txt - - info on the Trusted and Encrypted keys in the kernel key ring service. -keys.txt - - description of the kernel key retention service. -tomoyo.txt - - documentation on the TOMOYO Linux Security Module. -IMA-templates.txt - - documentation on the template management mechanism for IMA. diff --git a/Documentation/security/IMA-templates.txt b/Documentation/security/IMA-templates.rst index 839b5dad9226..2cd0e273cc9a 100644 --- a/Documentation/security/IMA-templates.txt +++ b/Documentation/security/IMA-templates.rst @@ -1,9 +1,12 @@ - IMA Template Management Mechanism +================================= +IMA Template Management Mechanism +================================= -==== INTRODUCTION ==== +Introduction +============ -The original 'ima' template is fixed length, containing the filedata hash +The original ``ima`` template is fixed length, containing the filedata hash and pathname. The filedata hash is limited to 20 bytes (md5/sha1). The pathname is a null terminated string, limited to 255 characters. To overcome these limitations and to add additional file metadata, it is @@ -28,61 +31,64 @@ a new data type, developers define the field identifier and implement two functions, init() and show(), respectively to generate and display measurement entries. Defining a new template descriptor requires specifying the template format (a string of field identifiers separated -by the '|' character) through the 'ima_template_fmt' kernel command line +by the ``|`` character) through the ``ima_template_fmt`` kernel command line parameter. At boot time, IMA initializes the chosen template descriptor by translating the format into an array of template fields structures taken from the set of the supported ones. -After the initialization step, IMA will call ima_alloc_init_template() +After the initialization step, IMA will call ``ima_alloc_init_template()`` (new function defined within the patches for the new template management mechanism) to generate a new measurement entry by using the template descriptor chosen through the kernel configuration or through the newly -introduced 'ima_template' and 'ima_template_fmt' kernel command line parameters. +introduced ``ima_template`` and ``ima_template_fmt`` kernel command line parameters. It is during this phase that the advantages of the new architecture are clearly shown: the latter function will not contain specific code to handle -a given template but, instead, it simply calls the init() method of the template +a given template but, instead, it simply calls the ``init()`` method of the template fields associated to the chosen template descriptor and store the result (pointer to allocated data and data length) in the measurement entry structure. The same mechanism is employed to display measurements entries. -The functions ima[_ascii]_measurements_show() retrieve, for each entry, +The functions ``ima[_ascii]_measurements_show()`` retrieve, for each entry, the template descriptor used to produce that entry and call the show() method for each item of the array of template fields structures. -==== SUPPORTED TEMPLATE FIELDS AND DESCRIPTORS ==== +Supported Template Fields and Descriptors +========================================= In the following, there is the list of supported template fields -('<identifier>': description), that can be used to define new template +``('<identifier>': description)``, that can be used to define new template descriptors by adding their identifier to the format string (support for more data types will be added later): - 'd': the digest of the event (i.e. the digest of a measured file), - calculated with the SHA1 or MD5 hash algorithm; + calculated with the SHA1 or MD5 hash algorithm; - 'n': the name of the event (i.e. the file name), with size up to 255 bytes; - 'd-ng': the digest of the event, calculated with an arbitrary hash - algorithm (field format: [<hash algo>:]digest, where the digest - prefix is shown only if the hash algorithm is not SHA1 or MD5); + algorithm (field format: [<hash algo>:]digest, where the digest + prefix is shown only if the hash algorithm is not SHA1 or MD5); - 'n-ng': the name of the event, without size limitations; - 'sig': the file signature. Below, there is the list of defined template descriptors: - - "ima": its format is 'd|n'; - - "ima-ng" (default): its format is 'd-ng|n-ng'; - - "ima-sig": its format is 'd-ng|n-ng|sig'. + - "ima": its format is ``d|n``; + - "ima-ng" (default): its format is ``d-ng|n-ng``; + - "ima-sig": its format is ``d-ng|n-ng|sig``. -==== USE ==== + +Use +=== To specify the template descriptor to be used to generate measurement entries, currently the following methods are supported: - select a template descriptor among those supported in the kernel - configuration ('ima-ng' is the default choice); + configuration (``ima-ng`` is the default choice); - specify a template descriptor name from the kernel command line through - the 'ima_template=' parameter; + the ``ima_template=`` parameter; - register a new template descriptor with custom format through the kernel - command line parameter 'ima_template_fmt='. + command line parameter ``ima_template_fmt=``. diff --git a/Documentation/security/LSM.rst b/Documentation/security/LSM.rst new file mode 100644 index 000000000000..d75778b0fa10 --- /dev/null +++ b/Documentation/security/LSM.rst @@ -0,0 +1,14 @@ +================================= +Linux Security Module Development +================================= + +Based on https://lkml.org/lkml/2007/10/26/215, +a new LSM is accepted into the kernel when its intent (a description of +what it tries to protect against and in what cases one would expect to +use it) has been appropriately documented in ``Documentation/security/LSM``. +This allows an LSM's code to be easily compared to its goals, and so +that end users and distros can make a more informed decision about which +LSMs suit their requirements. + +For extensive documentation on the available LSM hook interfaces, please +see ``include/linux/lsm_hooks.h``. diff --git a/Documentation/security/conf.py b/Documentation/security/conf.py deleted file mode 100644 index 472fc9a8eb67..000000000000 --- a/Documentation/security/conf.py +++ /dev/null @@ -1,8 +0,0 @@ -project = "The kernel security subsystem manual" - -tags.add("subproject") - -latex_documents = [ - ('index', 'security.tex', project, - 'The kernel development community', 'manual'), -] diff --git a/Documentation/security/credentials.txt b/Documentation/security/credentials.rst index 86257052e31a..038a7e19eff9 100644 --- a/Documentation/security/credentials.txt +++ b/Documentation/security/credentials.rst @@ -1,38 +1,18 @@ - ==================== - CREDENTIALS IN LINUX - ==================== +==================== +Credentials in Linux +==================== By: David Howells <dhowells@redhat.com> -Contents: - - (*) Overview. - - (*) Types of credentials. - - (*) File markings. - - (*) Task credentials. +.. contents:: :local: - - Immutable credentials. - - Accessing task credentials. - - Accessing another task's credentials. - - Altering credentials. - - Managing credentials. - - (*) Open file credentials. - - (*) Overriding the VFS's use of credentials. - - -======== -OVERVIEW +Overview ======== There are several parts to the security check performed by Linux when one object acts upon another: - (1) Objects. + 1. Objects. Objects are things in the system that may be acted upon directly by userspace programs. Linux has a variety of actionable objects, including: @@ -48,7 +28,7 @@ object acts upon another: As a part of the description of all these objects there is a set of credentials. What's in the set depends on the type of object. - (2) Object ownership. + 2. Object ownership. Amongst the credentials of most objects, there will be a subset that indicates the ownership of that object. This is used for resource @@ -57,7 +37,7 @@ object acts upon another: In a standard UNIX filesystem, for instance, this will be defined by the UID marked on the inode. - (3) The objective context. + 3. The objective context. Also amongst the credentials of those objects, there will be a subset that indicates the 'objective context' of that object. This may or may not be @@ -67,7 +47,7 @@ object acts upon another: The objective context is used as part of the security calculation that is carried out when an object is acted upon. - (4) Subjects. + 4. Subjects. A subject is an object that is acting upon another object. @@ -77,10 +57,10 @@ object acts upon another: Objects other than tasks may under some circumstances also be subjects. For instance an open file may send SIGIO to a task using the UID and EUID - given to it by a task that called fcntl(F_SETOWN) upon it. In this case, + given to it by a task that called ``fcntl(F_SETOWN)`` upon it. In this case, the file struct will have a subjective context too. - (5) The subjective context. + 5. The subjective context. A subject has an additional interpretation of its credentials. A subset of its credentials forms the 'subjective context'. The subjective context @@ -92,7 +72,7 @@ object acts upon another: from the real UID and GID that normally form the objective context of the task. - (6) Actions. + 6. Actions. Linux has a number of actions available that a subject may perform upon an object. The set of actions available depends on the nature of the subject @@ -101,7 +81,7 @@ object acts upon another: Actions include reading, writing, creating and deleting files; forking or signalling and tracing tasks. - (7) Rules, access control lists and security calculations. + 7. Rules, access control lists and security calculations. When a subject acts upon an object, a security calculation is made. This involves taking the subjective context, the objective context and the @@ -111,7 +91,7 @@ object acts upon another: There are two main sources of rules: - (a) Discretionary access control (DAC): + a. Discretionary access control (DAC): Sometimes the object will include sets of rules as part of its description. This is an 'Access Control List' or 'ACL'. A Linux @@ -127,7 +107,7 @@ object acts upon another: A Linux file might also sport a POSIX ACL. This is a list of rules that grants various permissions to arbitrary subjects. - (b) Mandatory access control (MAC): + b. Mandatory access control (MAC): The system as a whole may have one or more sets of rules that get applied to all subjects and objects, regardless of their source. @@ -139,65 +119,65 @@ object acts upon another: that says that this action is either granted or denied. -==================== -TYPES OF CREDENTIALS +Types of Credentials ==================== The Linux kernel supports the following types of credentials: - (1) Traditional UNIX credentials. + 1. Traditional UNIX credentials. - Real User ID - Real Group ID + - Real User ID + - Real Group ID The UID and GID are carried by most, if not all, Linux objects, even if in some cases it has to be invented (FAT or CIFS files for example, which are derived from Windows). These (mostly) define the objective context of that object, with tasks being slightly different in some cases. - Effective, Saved and FS User ID - Effective, Saved and FS Group ID - Supplementary groups + - Effective, Saved and FS User ID + - Effective, Saved and FS Group ID + - Supplementary groups These are additional credentials used by tasks only. Usually, an EUID/EGID/GROUPS will be used as the subjective context, and real UID/GID will be used as the objective. For tasks, it should be noted that this is not always true. - (2) Capabilities. + 2. Capabilities. - Set of permitted capabilities - Set of inheritable capabilities - Set of effective capabilities - Capability bounding set + - Set of permitted capabilities + - Set of inheritable capabilities + - Set of effective capabilities + - Capability bounding set These are only carried by tasks. They indicate superior capabilities granted piecemeal to a task that an ordinary task wouldn't otherwise have. These are manipulated implicitly by changes to the traditional UNIX - credentials, but can also be manipulated directly by the capset() system - call. + credentials, but can also be manipulated directly by the ``capset()`` + system call. The permitted capabilities are those caps that the process might grant - itself to its effective or permitted sets through capset(). This + itself to its effective or permitted sets through ``capset()``. This inheritable set might also be so constrained. The effective capabilities are the ones that a task is actually allowed to make use of itself. The inheritable capabilities are the ones that may get passed across - execve(). + ``execve()``. The bounding set limits the capabilities that may be inherited across - execve(), especially when a binary is executed that will execute as UID 0. + ``execve()``, especially when a binary is executed that will execute as + UID 0. - (3) Secure management flags (securebits). + 3. Secure management flags (securebits). These are only carried by tasks. These govern the way the above credentials are manipulated and inherited over certain operations such as execve(). They aren't used directly as objective or subjective credentials. - (4) Keys and keyrings. + 4. Keys and keyrings. These are only carried by tasks. They carry and cache security tokens that don't fit into the other standard UNIX credentials. They are for @@ -218,7 +198,7 @@ The Linux kernel supports the following types of credentials: For more information on using keys, see Documentation/security/keys.txt. - (5) LSM + 5. LSM The Linux Security Module allows extra controls to be placed over the operations that a task may do. Currently Linux supports several LSM @@ -228,7 +208,7 @@ The Linux kernel supports the following types of credentials: rules (policies) that say what operations a task with one label may do to an object with another label. - (6) AF_KEY + 6. AF_KEY This is a socket-based approach to credential management for networking stacks [RFC 2367]. It isn't discussed by this document as it doesn't @@ -244,25 +224,19 @@ network filesystem where the credentials of the opened file should be presented to the server, regardless of who is actually doing a read or a write upon it. -============= -FILE MARKINGS +File Markings ============= Files on disk or obtained over the network may have annotations that form the objective security context of that file. Depending on the type of filesystem, this may include one or more of the following: - (*) UNIX UID, GID, mode; - - (*) Windows user ID; - - (*) Access control list; - - (*) LSM security label; - - (*) UNIX exec privilege escalation bits (SUID/SGID); - - (*) File capabilities exec privilege escalation bits. + * UNIX UID, GID, mode; + * Windows user ID; + * Access control list; + * LSM security label; + * UNIX exec privilege escalation bits (SUID/SGID); + * File capabilities exec privilege escalation bits. These are compared to the task's subjective security context, and certain operations allowed or disallowed as a result. In the case of execve(), the @@ -270,8 +244,7 @@ privilege escalation bits come into play, and may allow the resulting process extra privileges, based on the annotations on the executable file. -================ -TASK CREDENTIALS +Task Credentials ================ In Linux, all of a task's credentials are held in (uid, gid) or through @@ -282,20 +255,20 @@ task_struct. Once a set of credentials has been prepared and committed, it may not be changed, barring the following exceptions: - (1) its reference count may be changed; + 1. its reference count may be changed; - (2) the reference count on the group_info struct it points to may be changed; + 2. the reference count on the group_info struct it points to may be changed; - (3) the reference count on the security data it points to may be changed; + 3. the reference count on the security data it points to may be changed; - (4) the reference count on any keyrings it points to may be changed; + 4. the reference count on any keyrings it points to may be changed; - (5) any keyrings it points to may be revoked, expired or have their security - attributes changed; and + 5. any keyrings it points to may be revoked, expired or have their security + attributes changed; and - (6) the contents of any keyrings to which it points may be changed (the whole - point of keyrings being a shared set of credentials, modifiable by anyone - with appropriate access). + 6. the contents of any keyrings to which it points may be changed (the whole + point of keyrings being a shared set of credentials, modifiable by anyone + with appropriate access). To alter anything in the cred struct, the copy-and-replace principle must be adhered to. First take a copy, then alter the copy and then use RCU to change @@ -303,37 +276,37 @@ the task pointer to make it point to the new copy. There are wrappers to aid with this (see below). A task may only alter its _own_ credentials; it is no longer permitted for a -task to alter another's credentials. This means the capset() system call is no -longer permitted to take any PID other than the one of the current process. -Also keyctl_instantiate() and keyctl_negate() functions no longer permit -attachment to process-specific keyrings in the requesting process as the -instantiating process may need to create them. +task to alter another's credentials. This means the ``capset()`` system call +is no longer permitted to take any PID other than the one of the current +process. Also ``keyctl_instantiate()`` and ``keyctl_negate()`` functions no +longer permit attachment to process-specific keyrings in the requesting +process as the instantiating process may need to create them. -IMMUTABLE CREDENTIALS +Immutable Credentials --------------------- -Once a set of credentials has been made public (by calling commit_creds() for -example), it must be considered immutable, barring two exceptions: +Once a set of credentials has been made public (by calling ``commit_creds()`` +for example), it must be considered immutable, barring two exceptions: - (1) The reference count may be altered. + 1. The reference count may be altered. - (2) Whilst the keyring subscriptions of a set of credentials may not be - changed, the keyrings subscribed to may have their contents altered. + 2. Whilst the keyring subscriptions of a set of credentials may not be + changed, the keyrings subscribed to may have their contents altered. To catch accidental credential alteration at compile time, struct task_struct has _const_ pointers to its credential sets, as does struct file. Furthermore, -certain functions such as get_cred() and put_cred() operate on const pointers, -thus rendering casts unnecessary, but require to temporarily ditch the const -qualification to be able to alter the reference count. +certain functions such as ``get_cred()`` and ``put_cred()`` operate on const +pointers, thus rendering casts unnecessary, but require to temporarily ditch +the const qualification to be able to alter the reference count. -ACCESSING TASK CREDENTIALS +Accessing Task Credentials -------------------------- A task being able to alter only its own credentials permits the current process to read or replace its own credentials without the need for any form of locking -- which simplifies things greatly. It can just call: +-- which simplifies things greatly. It can just call:: const struct cred *current_cred() @@ -341,7 +314,7 @@ to get a pointer to its credentials structure, and it doesn't have to release it afterwards. There are convenience wrappers for retrieving specific aspects of a task's -credentials (the value is simply returned in each case): +credentials (the value is simply returned in each case):: uid_t current_uid(void) Current's real UID gid_t current_gid(void) Current's real GID @@ -354,7 +327,7 @@ credentials (the value is simply returned in each case): struct user_struct *current_user(void) Current's user account There are also convenience wrappers for retrieving specific associated pairs of -a task's credentials: +a task's credentials:: void current_uid_gid(uid_t *, gid_t *); void current_euid_egid(uid_t *, gid_t *); @@ -365,12 +338,12 @@ them from the current task's credentials. In addition, there is a function for obtaining a reference on the current -process's current set of credentials: +process's current set of credentials:: const struct cred *get_current_cred(void); and functions for getting references to one of the credentials that don't -actually live in struct cred: +actually live in struct cred:: struct user_struct *get_current_user(void); struct group_info *get_current_groups(void); @@ -378,22 +351,22 @@ actually live in struct cred: which get references to the current process's user accounting structure and supplementary groups list respectively. -Once a reference has been obtained, it must be released with put_cred(), -free_uid() or put_group_info() as appropriate. +Once a reference has been obtained, it must be released with ``put_cred()``, +``free_uid()`` or ``put_group_info()`` as appropriate. -ACCESSING ANOTHER TASK'S CREDENTIALS +Accessing Another Task's Credentials ------------------------------------ Whilst a task may access its own credentials without the need for locking, the same is not true of a task wanting to access another task's credentials. It -must use the RCU read lock and rcu_dereference(). +must use the RCU read lock and ``rcu_dereference()``. -The rcu_dereference() is wrapped by: +The ``rcu_dereference()`` is wrapped by:: const struct cred *__task_cred(struct task_struct *task); -This should be used inside the RCU read lock, as in the following example: +This should be used inside the RCU read lock, as in the following example:: void foo(struct task_struct *t, struct foo_data *f) { @@ -410,39 +383,40 @@ This should be used inside the RCU read lock, as in the following example: Should it be necessary to hold another task's credentials for a long period of time, and possibly to sleep whilst doing so, then the caller should get a -reference on them using: +reference on them using:: const struct cred *get_task_cred(struct task_struct *task); This does all the RCU magic inside of it. The caller must call put_cred() on the credentials so obtained when they're finished with. - [*] Note: The result of __task_cred() should not be passed directly to - get_cred() as this may race with commit_cred(). +.. note:: + The result of ``__task_cred()`` should not be passed directly to + ``get_cred()`` as this may race with ``commit_cred()``. There are a couple of convenience functions to access bits of another task's -credentials, hiding the RCU magic from the caller: +credentials, hiding the RCU magic from the caller:: uid_t task_uid(task) Task's real UID uid_t task_euid(task) Task's effective UID -If the caller is holding the RCU read lock at the time anyway, then: +If the caller is holding the RCU read lock at the time anyway, then:: __task_cred(task)->uid __task_cred(task)->euid should be used instead. Similarly, if multiple aspects of a task's credentials -need to be accessed, RCU read lock should be used, __task_cred() called, the -result stored in a temporary pointer and then the credential aspects called +need to be accessed, RCU read lock should be used, ``__task_cred()`` called, +the result stored in a temporary pointer and then the credential aspects called from that before dropping the lock. This prevents the potentially expensive RCU magic from being invoked multiple times. Should some other single aspect of another task's credentials need to be -accessed, then this can be used: +accessed, then this can be used:: task_cred_xxx(task, member) -where 'member' is a non-pointer member of the cred struct. For instance: +where 'member' is a non-pointer member of the cred struct. For instance:: uid_t task_cred_xxx(task, suid); @@ -451,7 +425,7 @@ magic. This may not be used for pointer members as what they point to may disappear the moment the RCU read lock is dropped. -ALTERING CREDENTIALS +Altering Credentials -------------------- As previously mentioned, a task may only alter its own credentials, and may not @@ -459,7 +433,7 @@ alter those of another task. This means that it doesn't need to use any locking to alter its own credentials. To alter the current process's credentials, a function should first prepare a -new set of credentials by calling: +new set of credentials by calling:: struct cred *prepare_creds(void); @@ -467,9 +441,10 @@ this locks current->cred_replace_mutex and then allocates and constructs a duplicate of the current process's credentials, returning with the mutex still held if successful. It returns NULL if not successful (out of memory). -The mutex prevents ptrace() from altering the ptrace state of a process whilst -security checks on credentials construction and changing is taking place as -the ptrace state may alter the outcome, particularly in the case of execve(). +The mutex prevents ``ptrace()`` from altering the ptrace state of a process +whilst security checks on credentials construction and changing is taking place +as the ptrace state may alter the outcome, particularly in the case of +``execve()``. The new credentials set should be altered appropriately, and any security checks and hooks done. Both the current and the proposed sets of credentials @@ -478,36 +453,37 @@ still at this point. When the credential set is ready, it should be committed to the current process -by calling: +by calling:: int commit_creds(struct cred *new); This will alter various aspects of the credentials and the process, giving the -LSM a chance to do likewise, then it will use rcu_assign_pointer() to actually -commit the new credentials to current->cred, it will release -current->cred_replace_mutex to allow ptrace() to take place, and it will notify -the scheduler and others of the changes. +LSM a chance to do likewise, then it will use ``rcu_assign_pointer()`` to +actually commit the new credentials to ``current->cred``, it will release +``current->cred_replace_mutex`` to allow ``ptrace()`` to take place, and it +will notify the scheduler and others of the changes. This function is guaranteed to return 0, so that it can be tail-called at the -end of such functions as sys_setresuid(). +end of such functions as ``sys_setresuid()``. Note that this function consumes the caller's reference to the new credentials. -The caller should _not_ call put_cred() on the new credentials afterwards. +The caller should _not_ call ``put_cred()`` on the new credentials afterwards. Furthermore, once this function has been called on a new set of credentials, those credentials may _not_ be changed further. -Should the security checks fail or some other error occur after prepare_creds() -has been called, then the following function should be invoked: +Should the security checks fail or some other error occur after +``prepare_creds()`` has been called, then the following function should be +invoked:: void abort_creds(struct cred *new); -This releases the lock on current->cred_replace_mutex that prepare_creds() got -and then releases the new credentials. +This releases the lock on ``current->cred_replace_mutex`` that +``prepare_creds()`` got and then releases the new credentials. -A typical credentials alteration function would look something like this: +A typical credentials alteration function would look something like this:: int alter_suid(uid_t suid) { @@ -529,53 +505,50 @@ A typical credentials alteration function would look something like this: } -MANAGING CREDENTIALS +Managing Credentials -------------------- There are some functions to help manage credentials: - (*) void put_cred(const struct cred *cred); + - ``void put_cred(const struct cred *cred);`` This releases a reference to the given set of credentials. If the reference count reaches zero, the credentials will be scheduled for destruction by the RCU system. - (*) const struct cred *get_cred(const struct cred *cred); + - ``const struct cred *get_cred(const struct cred *cred);`` This gets a reference on a live set of credentials, returning a pointer to that set of credentials. - (*) struct cred *get_new_cred(struct cred *cred); + - ``struct cred *get_new_cred(struct cred *cred);`` This gets a reference on a set of credentials that is under construction and is thus still mutable, returning a pointer to that set of credentials. -===================== -OPEN FILE CREDENTIALS +Open File Credentials ===================== When a new file is opened, a reference is obtained on the opening task's -credentials and this is attached to the file struct as 'f_cred' in place of -'f_uid' and 'f_gid'. Code that used to access file->f_uid and file->f_gid -should now access file->f_cred->fsuid and file->f_cred->fsgid. +credentials and this is attached to the file struct as ``f_cred`` in place of +``f_uid`` and ``f_gid``. Code that used to access ``file->f_uid`` and +``file->f_gid`` should now access ``file->f_cred->fsuid`` and +``file->f_cred->fsgid``. -It is safe to access f_cred without the use of RCU or locking because the +It is safe to access ``f_cred`` without the use of RCU or locking because the pointer will not change over the lifetime of the file struct, and nor will the contents of the cred struct pointed to, barring the exceptions listed above (see the Task Credentials section). -======================================= -OVERRIDING THE VFS'S USE OF CREDENTIALS +Overriding the VFS's Use of Credentials ======================================= Under some circumstances it is desirable to override the credentials used by -the VFS, and that can be done by calling into such as vfs_mkdir() with a +the VFS, and that can be done by calling into such as ``vfs_mkdir()`` with a different set of credentials. This is done in the following places: - (*) sys_faccessat(). - - (*) do_coredump(). - - (*) nfs4recover.c. + * ``sys_faccessat()``. + * ``do_coredump()``. + * nfs4recover.c. diff --git a/Documentation/security/index.rst b/Documentation/security/index.rst index 9bae6bb20e7f..298a94a33f05 100644 --- a/Documentation/security/index.rst +++ b/Documentation/security/index.rst @@ -1,7 +1,13 @@ ====================== -Security documentation +Security Documentation ====================== .. toctree:: + :maxdepth: 1 + credentials + IMA-templates + keys/index + LSM + self-protection tpm/index diff --git a/Documentation/security/keys.txt b/Documentation/security/keys/core.rst index cd5019934d7f..0d831a7afe4f 100644 --- a/Documentation/security/keys.txt +++ b/Documentation/security/keys/core.rst @@ -1,6 +1,6 @@ - ============================ - KERNEL KEY RETENTION SERVICE - ============================ +============================ +Kernel Key Retention Service +============================ This service allows cryptographic keys, authentication tokens, cross-domain user mappings, and similar to be cached in the kernel for the use of @@ -29,8 +29,7 @@ This document has the following sections: - Garbage collection -============ -KEY OVERVIEW +Key Overview ============ In this context, keys represent units of cryptographic data, authentication @@ -47,14 +46,14 @@ Each key has a number of attributes: - State. - (*) Each key is issued a serial number of type key_serial_t that is unique for + * Each key is issued a serial number of type key_serial_t that is unique for the lifetime of that key. All serial numbers are positive non-zero 32-bit integers. Userspace programs can use a key's serial numbers as a way to gain access to it, subject to permission checking. - (*) Each key is of a defined "type". Types must be registered inside the + * Each key is of a defined "type". Types must be registered inside the kernel by a kernel service (such as a filesystem) before keys of that type can be added or used. Userspace programs cannot define new types directly. @@ -64,18 +63,18 @@ Each key has a number of attributes: Should a type be removed from the system, all the keys of that type will be invalidated. - (*) Each key has a description. This should be a printable string. The key + * Each key has a description. This should be a printable string. The key type provides an operation to perform a match between the description on a key and a criterion string. - (*) Each key has an owner user ID, a group ID and a permissions mask. These + * Each key has an owner user ID, a group ID and a permissions mask. These are used to control what a process may do to a key from userspace, and whether a kernel service will be able to find the key. - (*) Each key can be set to expire at a specific time by the key type's + * Each key can be set to expire at a specific time by the key type's instantiation function. Keys can also be immortal. - (*) Each key can have a payload. This is a quantity of data that represent the + * Each key can have a payload. This is a quantity of data that represent the actual "key". In the case of a keyring, this is a list of keys to which the keyring links; in the case of a user-defined key, it's an arbitrary blob of data. @@ -91,39 +90,38 @@ Each key has a number of attributes: permitted, another key type operation will be called to convert the key's attached payload back into a blob of data. - (*) Each key can be in one of a number of basic states: + * Each key can be in one of a number of basic states: - (*) Uninstantiated. The key exists, but does not have any data attached. + * Uninstantiated. The key exists, but does not have any data attached. Keys being requested from userspace will be in this state. - (*) Instantiated. This is the normal state. The key is fully formed, and + * Instantiated. This is the normal state. The key is fully formed, and has data attached. - (*) Negative. This is a relatively short-lived state. The key acts as a + * Negative. This is a relatively short-lived state. The key acts as a note saying that a previous call out to userspace failed, and acts as a throttle on key lookups. A negative key can be updated to a normal state. - (*) Expired. Keys can have lifetimes set. If their lifetime is exceeded, + * Expired. Keys can have lifetimes set. If their lifetime is exceeded, they traverse to this state. An expired key can be updated back to a normal state. - (*) Revoked. A key is put in this state by userspace action. It can't be + * Revoked. A key is put in this state by userspace action. It can't be found or operated upon (apart from by unlinking it). - (*) Dead. The key's type was unregistered, and so the key is now useless. + * Dead. The key's type was unregistered, and so the key is now useless. Keys in the last three states are subject to garbage collection. See the section on "Garbage collection". -==================== -KEY SERVICE OVERVIEW +Key Service Overview ==================== The key service provides a number of features besides keys: - (*) The key service defines three special key types: + * The key service defines three special key types: (+) "keyring" @@ -149,7 +147,7 @@ The key service provides a number of features besides keys: be created and updated from userspace, but the payload is only readable from kernel space. - (*) Each process subscribes to three keyrings: a thread-specific keyring, a + * Each process subscribes to three keyrings: a thread-specific keyring, a process-specific keyring, and a session-specific keyring. The thread-specific keyring is discarded from the child when any sort of @@ -170,7 +168,7 @@ The key service provides a number of features besides keys: The ownership of the thread keyring changes when the real UID and GID of the thread changes. - (*) Each user ID resident in the system holds two special keyrings: a user + * Each user ID resident in the system holds two special keyrings: a user specific keyring and a default user session keyring. The default session keyring is initialised with a link to the user-specific keyring. @@ -180,7 +178,7 @@ The key service provides a number of features besides keys: If a process attempts to access its session key when it doesn't have one, it will be subscribed to the default for its current UID. - (*) Each user has two quotas against which the keys they own are tracked. One + * Each user has two quotas against which the keys they own are tracked. One limits the total number of keys and keyrings, the other limits the total amount of description and payload space that can be consumed. @@ -194,54 +192,53 @@ The key service provides a number of features besides keys: If a system call that modifies a key or keyring in some way would put the user over quota, the operation is refused and error EDQUOT is returned. - (*) There's a system call interface by which userspace programs can create and + * There's a system call interface by which userspace programs can create and manipulate keys and keyrings. - (*) There's a kernel interface by which services can register types and search + * There's a kernel interface by which services can register types and search for keys. - (*) There's a way for the a search done from the kernel to call back to + * There's a way for the a search done from the kernel to call back to userspace to request a key that can't be found in a process's keyrings. - (*) An optional filesystem is available through which the key database can be + * An optional filesystem is available through which the key database can be viewed and manipulated. -====================== -KEY ACCESS PERMISSIONS +Key Access Permissions ====================== Keys have an owner user ID, a group access ID, and a permissions mask. The mask has up to eight bits each for possessor, user, group and other access. Only six of each set of eight bits are defined. These permissions granted are: - (*) View + * View This permits a key or keyring's attributes to be viewed - including key type and description. - (*) Read + * Read This permits a key's payload to be viewed or a keyring's list of linked keys. - (*) Write + * Write This permits a key's payload to be instantiated or updated, or it allows a link to be added to or removed from a keyring. - (*) Search + * Search This permits keyrings to be searched and keys to be found. Searches can only recurse into nested keyrings that have search permission set. - (*) Link + * Link This permits a key or keyring to be linked to. To create a link from a keyring to a key, a process must have Write permission on the keyring and Link permission on the key. - (*) Set Attribute + * Set Attribute This permits a key's UID, GID and permissions mask to be changed. @@ -249,8 +246,7 @@ For changing the ownership, group ID or permissions mask, being the owner of the key or having the sysadmin capability is sufficient. -=============== -SELINUX SUPPORT +SELinux Support =============== The security class "key" has been added to SELinux so that mandatory access @@ -282,14 +278,13 @@ their associated thread, and both session and process keyrings are handled similarly. -================ -NEW PROCFS FILES +New ProcFS Files ================ Two files have been added to procfs by which an administrator can find out about the status of the key service: - (*) /proc/keys + * /proc/keys This lists the keys that are currently viewable by the task reading the file, giving information about their type, description and permissions. @@ -301,7 +296,7 @@ about the status of the key service: security checks are still performed, and may further filter out keys that the current process is not authorised to view. - The contents of the file look like this: + The contents of the file look like this:: SERIAL FLAGS USAGE EXPY PERM UID GID TYPE DESCRIPTION: SUMMARY 00000001 I----- 39 perm 1f3f0000 0 0 keyring _uid_ses.0: 1/4 @@ -314,7 +309,7 @@ about the status of the key service: 00000893 I--Q-N 1 35s 1f3f0000 0 0 user metal:silver: 0 00000894 I--Q-- 1 10h 003f0000 0 0 user metal:gold: 0 - The flags are: + The flags are:: I Instantiated R Revoked @@ -324,10 +319,10 @@ about the status of the key service: N Negative key - (*) /proc/key-users + * /proc/key-users This file lists the tracking data for each user that has at least one key - on the system. Such data includes quota information and statistics: + on the system. Such data includes quota information and statistics:: [root@andromeda root]# cat /proc/key-users 0: 46 45/45 1/100 13/10000 @@ -335,7 +330,8 @@ about the status of the key service: 32: 2 2/2 2/100 40/10000 38: 2 2/2 2/100 40/10000 - The format of each line is + The format of each line is:: + <UID>: User ID to which this applies <usage> Structure refcount <inst>/<keys> Total number of keys and number instantiated @@ -346,14 +342,14 @@ about the status of the key service: Four new sysctl files have been added also for the purpose of controlling the quota limits on keys: - (*) /proc/sys/kernel/keys/root_maxkeys + * /proc/sys/kernel/keys/root_maxkeys /proc/sys/kernel/keys/root_maxbytes These files hold the maximum number of keys that root may have and the maximum total number of bytes of data that root may have stored in those keys. - (*) /proc/sys/kernel/keys/maxkeys + * /proc/sys/kernel/keys/maxkeys /proc/sys/kernel/keys/maxbytes These files hold the maximum number of keys that each non-root user may @@ -364,8 +360,7 @@ Root may alter these by writing each new limit as a decimal number string to the appropriate file. -=============================== -USERSPACE SYSTEM CALL INTERFACE +Userspace System Call Interface =============================== Userspace can manipulate keys directly through three new syscalls: add_key, @@ -375,7 +370,7 @@ manipulating keys. When referring to a key directly, userspace programs should use the key's serial number (a positive 32-bit integer). However, there are some special values available for referring to special keys and keyrings that relate to the -process making the call: +process making the call:: CONSTANT VALUE KEY REFERENCED ============================== ====== =========================== @@ -391,8 +386,8 @@ process making the call: The main syscalls are: - (*) Create a new key of given type, description and payload and add it to the - nominated keyring: + * Create a new key of given type, description and payload and add it to the + nominated keyring:: key_serial_t add_key(const char *type, const char *desc, const void *payload, size_t plen, @@ -432,8 +427,8 @@ The main syscalls are: The ID of the new or updated key is returned if successful. - (*) Search the process's keyrings for a key, potentially calling out to - userspace to create it. + * Search the process's keyrings for a key, potentially calling out to + userspace to create it:: key_serial_t request_key(const char *type, const char *description, const char *callout_info, @@ -453,7 +448,7 @@ The main syscalls are: The keyctl syscall functions are: - (*) Map a special key ID to a real key ID for this process: + * Map a special key ID to a real key ID for this process:: key_serial_t keyctl(KEYCTL_GET_KEYRING_ID, key_serial_t id, int create); @@ -466,7 +461,7 @@ The keyctl syscall functions are: non-zero; and the error ENOKEY will be returned if "create" is zero. - (*) Replace the session keyring this process subscribes to with a new one: + * Replace the session keyring this process subscribes to with a new one:: key_serial_t keyctl(KEYCTL_JOIN_SESSION_KEYRING, const char *name); @@ -484,7 +479,7 @@ The keyctl syscall functions are: The ID of the new session keyring is returned if successful. - (*) Update the specified key: + * Update the specified key:: long keyctl(KEYCTL_UPDATE, key_serial_t key, const void *payload, size_t plen); @@ -498,7 +493,7 @@ The keyctl syscall functions are: add_key(). - (*) Revoke a key: + * Revoke a key:: long keyctl(KEYCTL_REVOKE, key_serial_t key); @@ -507,7 +502,7 @@ The keyctl syscall functions are: be findable. - (*) Change the ownership of a key: + * Change the ownership of a key:: long keyctl(KEYCTL_CHOWN, key_serial_t key, uid_t uid, gid_t gid); @@ -520,7 +515,7 @@ The keyctl syscall functions are: its group list members. - (*) Change the permissions mask on a key: + * Change the permissions mask on a key:: long keyctl(KEYCTL_SETPERM, key_serial_t key, key_perm_t perm); @@ -531,7 +526,7 @@ The keyctl syscall functions are: error EINVAL will be returned. - (*) Describe a key: + * Describe a key:: long keyctl(KEYCTL_DESCRIBE, key_serial_t key, char *buffer, size_t buflen); @@ -547,7 +542,7 @@ The keyctl syscall functions are: A process must have view permission on the key for this function to be successful. - If successful, a string is placed in the buffer in the following format: + If successful, a string is placed in the buffer in the following format:: <type>;<uid>;<gid>;<perm>;<description> @@ -555,12 +550,12 @@ The keyctl syscall functions are: is hexadecimal. A NUL character is included at the end of the string if the buffer is sufficiently big. - This can be parsed with + This can be parsed with:: sscanf(buffer, "%[^;];%d;%d;%o;%s", type, &uid, &gid, &mode, desc); - (*) Clear out a keyring: + * Clear out a keyring:: long keyctl(KEYCTL_CLEAR, key_serial_t keyring); @@ -573,7 +568,7 @@ The keyctl syscall functions are: DNS resolver cache keyring is an example of this. - (*) Link a key into a keyring: + * Link a key into a keyring:: long keyctl(KEYCTL_LINK, key_serial_t keyring, key_serial_t key); @@ -592,7 +587,7 @@ The keyctl syscall functions are: added. - (*) Unlink a key or keyring from another keyring: + * Unlink a key or keyring from another keyring:: long keyctl(KEYCTL_UNLINK, key_serial_t keyring, key_serial_t key); @@ -604,7 +599,7 @@ The keyctl syscall functions are: is not present, error ENOENT will be the result. - (*) Search a keyring tree for a key: + * Search a keyring tree for a key:: key_serial_t keyctl(KEYCTL_SEARCH, key_serial_t keyring, const char *type, const char *description, @@ -628,7 +623,7 @@ The keyctl syscall functions are: fails. On success, the resulting key ID will be returned. - (*) Read the payload data from a key: + * Read the payload data from a key:: long keyctl(KEYCTL_READ, key_serial_t keyring, char *buffer, size_t buflen); @@ -650,7 +645,7 @@ The keyctl syscall functions are: available rather than the amount copied. - (*) Instantiate a partially constructed key. + * Instantiate a partially constructed key:: long keyctl(KEYCTL_INSTANTIATE, key_serial_t key, const void *payload, size_t plen, @@ -677,7 +672,7 @@ The keyctl syscall functions are: array instead of a single buffer. - (*) Negatively instantiate a partially constructed key. + * Negatively instantiate a partially constructed key:: long keyctl(KEYCTL_NEGATE, key_serial_t key, unsigned timeout, key_serial_t keyring); @@ -700,12 +695,12 @@ The keyctl syscall functions are: as rejecting the key with ENOKEY as the error code. - (*) Set the default request-key destination keyring. + * Set the default request-key destination keyring:: long keyctl(KEYCTL_SET_REQKEY_KEYRING, int reqkey_defl); This sets the default keyring to which implicitly requested keys will be - attached for this thread. reqkey_defl should be one of these constants: + attached for this thread. reqkey_defl should be one of these constants:: CONSTANT VALUE NEW DEFAULT KEYRING ====================================== ====== ======================= @@ -731,7 +726,7 @@ The keyctl syscall functions are: there is one, otherwise the user default session keyring. - (*) Set the timeout on a key. + * Set the timeout on a key:: long keyctl(KEYCTL_SET_TIMEOUT, key_serial_t key, unsigned timeout); @@ -744,7 +739,7 @@ The keyctl syscall functions are: or expired keys. - (*) Assume the authority granted to instantiate a key + * Assume the authority granted to instantiate a key:: long keyctl(KEYCTL_ASSUME_AUTHORITY, key_serial_t key); @@ -766,7 +761,7 @@ The keyctl syscall functions are: The assumed authoritative key is inherited across fork and exec. - (*) Get the LSM security context attached to a key. + * Get the LSM security context attached to a key:: long keyctl(KEYCTL_GET_SECURITY, key_serial_t key, char *buffer, size_t buflen) @@ -787,7 +782,7 @@ The keyctl syscall functions are: successful. - (*) Install the calling process's session keyring on its parent. + * Install the calling process's session keyring on its parent:: long keyctl(KEYCTL_SESSION_TO_PARENT); @@ -807,7 +802,7 @@ The keyctl syscall functions are: kernel and resumes executing userspace. - (*) Invalidate a key. + * Invalidate a key:: long keyctl(KEYCTL_INVALIDATE, key_serial_t key); @@ -823,20 +818,19 @@ The keyctl syscall functions are: A process must have search permission on the key for this function to be successful. - (*) Compute a Diffie-Hellman shared secret or public key + * Compute a Diffie-Hellman shared secret or public key:: - long keyctl(KEYCTL_DH_COMPUTE, struct keyctl_dh_params *params, - char *buffer, size_t buflen, - struct keyctl_kdf_params *kdf); + long keyctl(KEYCTL_DH_COMPUTE, struct keyctl_dh_params *params, + char *buffer, size_t buflen, struct keyctl_kdf_params *kdf); - The params struct contains serial numbers for three keys: + The params struct contains serial numbers for three keys:: - The prime, p, known to both parties - The local private key - The base integer, which is either a shared generator or the remote public key - The value computed is: + The value computed is:: result = base ^ private (mod prime) @@ -858,12 +852,12 @@ The keyctl syscall functions are: of the KDF is returned to the caller. The KDF is characterized with struct keyctl_kdf_params as follows: - - char *hashname specifies the NUL terminated string identifying + - ``char *hashname`` specifies the NUL terminated string identifying the hash used from the kernel crypto API and applied for the KDF operation. The KDF implemenation complies with SP800-56A as well as with SP800-108 (the counter KDF). - - char *otherinfo specifies the OtherInfo data as documented in + - ``char *otherinfo`` specifies the OtherInfo data as documented in SP800-56A section 5.8.1.2. The length of the buffer is given with otherinfolen. The format of OtherInfo is defined by the caller. The otherinfo pointer may be NULL if no OtherInfo shall be used. @@ -875,10 +869,10 @@ The keyctl syscall functions are: and either the buffer length or the OtherInfo length exceeds the allowed length. - (*) Restrict keyring linkage + * Restrict keyring linkage:: - long keyctl(KEYCTL_RESTRICT_KEYRING, key_serial_t keyring, - const char *type, const char *restriction); + long keyctl(KEYCTL_RESTRICT_KEYRING, key_serial_t keyring, + const char *type, const char *restriction); An existing keyring can restrict linkage of additional keys by evaluating the contents of the key according to a restriction scheme. @@ -900,8 +894,7 @@ The keyctl syscall functions are: To apply a keyring restriction the process must have Set Attribute permission and the keyring must not be previously restricted. -=============== -KERNEL SERVICES +Kernel Services =============== The kernel services for key management are fairly simple to deal with. They can @@ -915,29 +908,29 @@ call, and the key released upon close. How to deal with conflicting keys due to two different users opening the same file is left to the filesystem author to solve. -To access the key manager, the following header must be #included: +To access the key manager, the following header must be #included:: <linux/key.h> Specific key types should have a header file under include/keys/ that should be -used to access that type. For keys of type "user", for example, that would be: +used to access that type. For keys of type "user", for example, that would be:: <keys/user-type.h> Note that there are two different types of pointers to keys that may be encountered: - (*) struct key * + * struct key * This simply points to the key structure itself. Key structures will be at least four-byte aligned. - (*) key_ref_t + * key_ref_t - This is equivalent to a struct key *, but the least significant bit is set + This is equivalent to a ``struct key *``, but the least significant bit is set if the caller "possesses" the key. By "possession" it is meant that the calling processes has a searchable link to the key from one of its - keyrings. There are three functions for dealing with these: + keyrings. There are three functions for dealing with these:: key_ref_t make_key_ref(const struct key *key, bool possession); @@ -955,7 +948,7 @@ When accessing a key's payload contents, certain precautions must be taken to prevent access vs modification races. See the section "Notes on accessing payload contents" for more information. -(*) To search for a key, call: + * To search for a key, call:: struct key *request_key(const struct key_type *type, const char *description, @@ -977,7 +970,7 @@ payload contents" for more information. See also Documentation/security/keys-request-key.txt. -(*) To search for a key, passing auxiliary data to the upcaller, call: + * To search for a key, passing auxiliary data to the upcaller, call:: struct key *request_key_with_auxdata(const struct key_type *type, const char *description, @@ -990,14 +983,14 @@ payload contents" for more information. is a blob of length callout_len, if given (the length may be 0). -(*) A key can be requested asynchronously by calling one of: + * A key can be requested asynchronously by calling one of:: struct key *request_key_async(const struct key_type *type, const char *description, const void *callout_info, size_t callout_len); - or: + or:: struct key *request_key_async_with_auxdata(const struct key_type *type, const char *description, @@ -1010,7 +1003,7 @@ payload contents" for more information. These two functions return with the key potentially still under construction. To wait for construction completion, the following should be - called: + called:: int wait_for_key_construction(struct key *key, bool intr); @@ -1022,11 +1015,11 @@ payload contents" for more information. case error ERESTARTSYS will be returned. -(*) When it is no longer required, the key should be released using: + * When it is no longer required, the key should be released using:: void key_put(struct key *key); - Or: + Or:: void key_ref_put(key_ref_t key_ref); @@ -1034,8 +1027,8 @@ payload contents" for more information. the argument will not be parsed. -(*) Extra references can be made to a key by calling one of the following - functions: + * Extra references can be made to a key by calling one of the following + functions:: struct key *__key_get(struct key *key); struct key *key_get(struct key *key); @@ -1047,7 +1040,7 @@ payload contents" for more information. then the key will not be dereferenced and no increment will take place. -(*) A key's serial number can be obtained by calling: + * A key's serial number can be obtained by calling:: key_serial_t key_serial(struct key *key); @@ -1055,7 +1048,7 @@ payload contents" for more information. latter case without parsing the argument). -(*) If a keyring was found in the search, this can be further searched by: + * If a keyring was found in the search, this can be further searched by:: key_ref_t keyring_search(key_ref_t keyring_ref, const struct key_type *type, @@ -1070,7 +1063,7 @@ payload contents" for more information. reference pointer if successful. -(*) A keyring can be created by: + * A keyring can be created by:: struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid, const struct cred *cred, @@ -1109,7 +1102,7 @@ payload contents" for more information. -EPERM to in this case. -(*) To check the validity of a key, this function can be called: + * To check the validity of a key, this function can be called:: int validate_key(struct key *key); @@ -1119,7 +1112,7 @@ payload contents" for more information. returned (in the latter case without parsing the argument). -(*) To register a key type, the following function should be called: + * To register a key type, the following function should be called:: int register_key_type(struct key_type *type); @@ -1127,13 +1120,13 @@ payload contents" for more information. present. -(*) To unregister a key type, call: + * To unregister a key type, call:: void unregister_key_type(struct key_type *type); Under some circumstances, it may be desirable to deal with a bundle of keys. -The facility provides access to the keyring type for managing such a bundle: +The facility provides access to the keyring type for managing such a bundle:: struct key_type key_type_keyring; @@ -1143,8 +1136,7 @@ with keyring_search(). Note that it is not possible to use request_key() to search a specific keyring, so using keyrings in this way is of limited utility. -=================================== -NOTES ON ACCESSING PAYLOAD CONTENTS +Notes On Accessing Payload Contents =================================== The simplest payload is just data stored in key->payload directly. In this @@ -1154,31 +1146,31 @@ More complex payload contents must be allocated and pointers to them set in the key->payload.data[] array. One of the following ways must be selected to access the data: - (1) Unmodifiable key type. + 1) Unmodifiable key type. If the key type does not have a modify method, then the key's payload can be accessed without any form of locking, provided that it's known to be instantiated (uninstantiated keys cannot be "found"). - (2) The key's semaphore. + 2) The key's semaphore. The semaphore could be used to govern access to the payload and to control the payload pointer. It must be write-locked for modifications and would have to be read-locked for general access. The disadvantage of doing this is that the accessor may be required to sleep. - (3) RCU. + 3) RCU. RCU must be used when the semaphore isn't already held; if the semaphore is held then the contents can't change under you unexpectedly as the semaphore must still be used to serialise modifications to the key. The key management code takes care of this for the key type. - However, this means using: + However, this means using:: rcu_read_lock() ... rcu_dereference() ... rcu_read_unlock() - to read the pointer, and: + to read the pointer, and:: rcu_dereference() ... rcu_assign_pointer() ... call_rcu() @@ -1194,11 +1186,11 @@ access the data: usage. This is called key->payload.rcu_data0. The following accessors wrap the RCU calls to this element: - (a) Set or change the first payload pointer: + a) Set or change the first payload pointer:: rcu_assign_keypointer(struct key *key, void *data); - (b) Read the first payload pointer with the key semaphore held: + b) Read the first payload pointer with the key semaphore held:: [const] void *dereference_key_locked([const] struct key *key); @@ -1206,39 +1198,38 @@ access the data: parameter. Static analysis will give an error if it things the lock isn't held. - (c) Read the first payload pointer with the RCU read lock held: + c) Read the first payload pointer with the RCU read lock held:: const void *dereference_key_rcu(const struct key *key); -=================== -DEFINING A KEY TYPE +Defining a Key Type =================== A kernel service may want to define its own key type. For instance, an AFS filesystem might want to define a Kerberos 5 ticket key type. To do this, it author fills in a key_type struct and registers it with the system. -Source files that implement key types should include the following header file: +Source files that implement key types should include the following header file:: <linux/key-type.h> The structure has a number of fields, some of which are mandatory: - (*) const char *name + * ``const char *name`` The name of the key type. This is used to translate a key type name supplied by userspace into a pointer to the structure. - (*) size_t def_datalen + * ``size_t def_datalen`` This is optional - it supplies the default payload data length as contributed to the quota. If the key type's payload is always or almost always the same size, then this is a more efficient way to do things. The data length (and quota) on a particular key can always be changed - during instantiation or update by calling: + during instantiation or update by calling:: int key_payload_reserve(struct key *key, size_t datalen); @@ -1246,18 +1237,18 @@ The structure has a number of fields, some of which are mandatory: viable. - (*) int (*vet_description)(const char *description); + * ``int (*vet_description)(const char *description);`` This optional method is called to vet a key description. If the key type doesn't approve of the key description, it may return an error, otherwise it should return 0. - (*) int (*preparse)(struct key_preparsed_payload *prep); + * ``int (*preparse)(struct key_preparsed_payload *prep);`` This optional method permits the key type to attempt to parse payload before a key is created (add key) or the key semaphore is taken (update or - instantiate key). The structure pointed to by prep looks like: + instantiate key). The structure pointed to by prep looks like:: struct key_preparsed_payload { char *description; @@ -1285,7 +1276,7 @@ The structure has a number of fields, some of which are mandatory: otherwise. - (*) void (*free_preparse)(struct key_preparsed_payload *prep); + * ``void (*free_preparse)(struct key_preparsed_payload *prep);`` This method is only required if the preparse() method is provided, otherwise it is unused. It cleans up anything attached to the description @@ -1294,7 +1285,7 @@ The structure has a number of fields, some of which are mandatory: successfully, even if instantiate() or update() succeed. - (*) int (*instantiate)(struct key *key, struct key_preparsed_payload *prep); + * ``int (*instantiate)(struct key *key, struct key_preparsed_payload *prep);`` This method is called to attach a payload to a key during construction. The payload attached need not bear any relation to the data passed to this @@ -1318,7 +1309,7 @@ The structure has a number of fields, some of which are mandatory: free_preparse method doesn't release the data. - (*) int (*update)(struct key *key, const void *data, size_t datalen); + * ``int (*update)(struct key *key, const void *data, size_t datalen);`` If this type of key can be updated, then this method should be provided. It is called to update a key's payload from the blob of data provided. @@ -1343,10 +1334,10 @@ The structure has a number of fields, some of which are mandatory: It is safe to sleep in this method. - (*) int (*match_preparse)(struct key_match_data *match_data); + * ``int (*match_preparse)(struct key_match_data *match_data);`` This method is optional. It is called when a key search is about to be - performed. It is given the following structure: + performed. It is given the following structure:: struct key_match_data { bool (*cmp)(const struct key *key, @@ -1357,23 +1348,23 @@ The structure has a number of fields, some of which are mandatory: }; On entry, raw_data will be pointing to the criteria to be used in matching - a key by the caller and should not be modified. (*cmp)() will be pointing + a key by the caller and should not be modified. ``(*cmp)()`` will be pointing to the default matcher function (which does an exact description match against raw_data) and lookup_type will be set to indicate a direct lookup. The following lookup_type values are available: - [*] KEYRING_SEARCH_LOOKUP_DIRECT - A direct lookup hashes the type and + * KEYRING_SEARCH_LOOKUP_DIRECT - A direct lookup hashes the type and description to narrow down the search to a small number of keys. - [*] KEYRING_SEARCH_LOOKUP_ITERATE - An iterative lookup walks all the + * KEYRING_SEARCH_LOOKUP_ITERATE - An iterative lookup walks all the keys in the keyring until one is matched. This must be used for any search that's not doing a simple direct match on the key description. The method may set cmp to point to a function of its choice that does some other form of match, may set lookup_type to KEYRING_SEARCH_LOOKUP_ITERATE - and may attach something to the preparsed pointer for use by (*cmp)(). - (*cmp)() should return true if a key matches and false otherwise. + and may attach something to the preparsed pointer for use by ``(*cmp)()``. + ``(*cmp)()`` should return true if a key matches and false otherwise. If preparsed is set, it may be necessary to use the match_free() method to clean it up. @@ -1381,20 +1372,20 @@ The structure has a number of fields, some of which are mandatory: The method should return 0 if successful or a negative error code otherwise. - It is permitted to sleep in this method, but (*cmp)() may not sleep as + It is permitted to sleep in this method, but ``(*cmp)()`` may not sleep as locks will be held over it. If match_preparse() is not provided, keys of this type will be matched exactly by their description. - (*) void (*match_free)(struct key_match_data *match_data); + * ``void (*match_free)(struct key_match_data *match_data);`` This method is optional. If given, it called to clean up match_data->preparsed after a successful call to match_preparse(). - (*) void (*revoke)(struct key *key); + * ``void (*revoke)(struct key *key);`` This method is optional. It is called to discard part of the payload data upon a key being revoked. The caller will have the key semaphore @@ -1404,7 +1395,7 @@ The structure has a number of fields, some of which are mandatory: a deadlock against the key semaphore. - (*) void (*destroy)(struct key *key); + * ``void (*destroy)(struct key *key);`` This method is optional. It is called to discard the payload data on a key when it is being destroyed. @@ -1416,7 +1407,7 @@ The structure has a number of fields, some of which are mandatory: It is not safe to sleep in this method; the caller may hold spinlocks. - (*) void (*describe)(const struct key *key, struct seq_file *p); + * ``void (*describe)(const struct key *key, struct seq_file *p);`` This method is optional. It is called during /proc/keys reading to summarise a key's description and payload in text form. @@ -1432,7 +1423,7 @@ The structure has a number of fields, some of which are mandatory: caller. - (*) long (*read)(const struct key *key, char __user *buffer, size_t buflen); + * ``long (*read)(const struct key *key, char __user *buffer, size_t buflen);`` This method is optional. It is called by KEYCTL_READ to translate the key's payload into something a blob of data for userspace to deal with. @@ -1448,8 +1439,7 @@ The structure has a number of fields, some of which are mandatory: as might happen when the userspace buffer is accessed. - (*) int (*request_key)(struct key_construction *cons, const char *op, - void *aux); + * ``int (*request_key)(struct key_construction *cons, const char *op, void *aux);`` This method is optional. If provided, request_key() and friends will invoke this function rather than upcalling to /sbin/request-key to operate @@ -1463,7 +1453,7 @@ The structure has a number of fields, some of which are mandatory: This method is permitted to return before the upcall is complete, but the following function must be called under all circumstances to complete the instantiation process, whether or not it succeeds, whether or not there's - an error: + an error:: void complete_request_key(struct key_construction *cons, int error); @@ -1479,16 +1469,16 @@ The structure has a number of fields, some of which are mandatory: The key under construction and the authorisation key can be found in the key_construction struct pointed to by cons: - (*) struct key *key; + * ``struct key *key;`` The key under construction. - (*) struct key *authkey; + * ``struct key *authkey;`` The authorisation key. - (*) struct key_restriction *(*lookup_restriction)(const char *params); + * ``struct key_restriction *(*lookup_restriction)(const char *params);`` This optional method is used to enable userspace configuration of keyring restrictions. The restriction parameter string (not including the key type @@ -1497,12 +1487,11 @@ The structure has a number of fields, some of which are mandatory: attempted key link operation. If there is no match, -EINVAL is returned. -============================ -REQUEST-KEY CALLBACK SERVICE +Request-Key Callback Service ============================ To create a new key, the kernel will attempt to execute the following command -line: +line:: /sbin/request-key create <key> <uid> <gid> \ <threadring> <processring> <sessionring> <callout_info> @@ -1511,10 +1500,10 @@ line: keyrings from the process that caused the search to be issued. These are included for two reasons: - (1) There may be an authentication token in one of the keyrings that is + 1 There may be an authentication token in one of the keyrings that is required to obtain the key, eg: a Kerberos Ticket-Granting Ticket. - (2) The new key should probably be cached in one of these rings. + 2 The new key should probably be cached in one of these rings. This program should set it UID and GID to those specified before attempting to access any more keys. It may then look around for a user specific process to @@ -1539,7 +1528,7 @@ instead. Similarly, the kernel may attempt to update an expired or a soon to expire key -by executing: +by executing:: /sbin/request-key update <key> <uid> <gid> \ <threadring> <processring> <sessionring> @@ -1548,8 +1537,7 @@ In this case, the program isn't required to actually attach the key to a ring; the rings are provided for reference. -================== -GARBAGE COLLECTION +Garbage Collection ================== Dead keys (for which the type has been removed) will be automatically unlinked @@ -1557,6 +1545,6 @@ from those keyrings that point to them and deleted as soon as possible by a background garbage collector. Similarly, revoked and expired keys will be garbage collected, but only after a -certain amount of time has passed. This time is set as a number of seconds in: +certain amount of time has passed. This time is set as a number of seconds in:: /proc/sys/kernel/keys/gc_delay diff --git a/Documentation/security/keys-ecryptfs.txt b/Documentation/security/keys/ecryptfs.rst index c3bbeba63562..4920f3a8ea75 100644 --- a/Documentation/security/keys-ecryptfs.txt +++ b/Documentation/security/keys/ecryptfs.rst @@ -1,4 +1,6 @@ - Encrypted keys for the eCryptfs filesystem +========================================== +Encrypted keys for the eCryptfs filesystem +========================================== ECryptfs is a stacked filesystem which transparently encrypts and decrypts each file using a randomly generated File Encryption Key (FEK). @@ -35,20 +37,23 @@ controlled environment. Another advantage is that the key is not exposed to threats of malicious software, because it is available in clear form only at kernel level. -Usage: +Usage:: + keyctl add encrypted name "new ecryptfs key-type:master-key-name keylen" ring keyctl add encrypted name "load hex_blob" ring keyctl update keyid "update key-type:master-key-name" -name:= '<16 hexadecimal characters>' -key-type:= 'trusted' | 'user' -keylen:= 64 +Where:: + + name:= '<16 hexadecimal characters>' + key-type:= 'trusted' | 'user' + keylen:= 64 Example of encrypted key usage with the eCryptfs filesystem: Create an encrypted key "1000100010001000" of length 64 bytes with format -'ecryptfs' and save it using a previously loaded user key "test": +'ecryptfs' and save it using a previously loaded user key "test":: $ keyctl add encrypted 1000100010001000 "new ecryptfs user:test 64" @u 19184530 @@ -62,7 +67,7 @@ Create an encrypted key "1000100010001000" of length 64 bytes with format $ keyctl pipe 19184530 > ecryptfs.blob Mount an eCryptfs filesystem using the created encrypted key "1000100010001000" -into the '/secret' directory: +into the '/secret' directory:: $ mount -i -t ecryptfs -oecryptfs_sig=1000100010001000,\ ecryptfs_cipher=aes,ecryptfs_key_bytes=32 /secret /secret diff --git a/Documentation/security/keys/index.rst b/Documentation/security/keys/index.rst new file mode 100644 index 000000000000..647d58f2588e --- /dev/null +++ b/Documentation/security/keys/index.rst @@ -0,0 +1,11 @@ +=========== +Kernel Keys +=========== + +.. toctree:: + :maxdepth: 1 + + core + ecryptfs + request-key + trusted-encrypted diff --git a/Documentation/security/keys-request-key.txt b/Documentation/security/keys/request-key.rst index 51987bfecfed..aba32784174c 100644 --- a/Documentation/security/keys-request-key.txt +++ b/Documentation/security/keys/request-key.rst @@ -1,19 +1,19 @@ - =================== - KEY REQUEST SERVICE - =================== +=================== +Key Request Service +=================== The key request service is part of the key retention service (refer to Documentation/security/keys.txt). This document explains more fully how the requesting algorithm works. The process starts by either the kernel requesting a service by calling -request_key*(): +``request_key*()``:: struct key *request_key(const struct key_type *type, const char *description, const char *callout_info); -or: +or:: struct key *request_key_with_auxdata(const struct key_type *type, const char *description, @@ -21,14 +21,14 @@ or: size_t callout_len, void *aux); -or: +or:: struct key *request_key_async(const struct key_type *type, const char *description, const char *callout_info, size_t callout_len); -or: +or:: struct key *request_key_async_with_auxdata(const struct key_type *type, const char *description, @@ -36,7 +36,7 @@ or: size_t callout_len, void *aux); -Or by userspace invoking the request_key system call: +Or by userspace invoking the request_key system call:: key_serial_t request_key(const char *type, const char *description, @@ -67,38 +67,37 @@ own upcall mechanisms. If they do, then those should be substituted for the forking and execution of /sbin/request-key. -=========== -THE PROCESS +The Process =========== A request proceeds in the following manner: - (1) Process A calls request_key() [the userspace syscall calls the kernel + 1) Process A calls request_key() [the userspace syscall calls the kernel interface]. - (2) request_key() searches the process's subscribed keyrings to see if there's + 2) request_key() searches the process's subscribed keyrings to see if there's a suitable key there. If there is, it returns the key. If there isn't, and callout_info is not set, an error is returned. Otherwise the process proceeds to the next step. - (3) request_key() sees that A doesn't have the desired key yet, so it creates + 3) request_key() sees that A doesn't have the desired key yet, so it creates two things: - (a) An uninstantiated key U of requested type and description. + a) An uninstantiated key U of requested type and description. - (b) An authorisation key V that refers to key U and notes that process A + b) An authorisation key V that refers to key U and notes that process A is the context in which key U should be instantiated and secured, and from which associated key requests may be satisfied. - (4) request_key() then forks and executes /sbin/request-key with a new session + 4) request_key() then forks and executes /sbin/request-key with a new session keyring that contains a link to auth key V. - (5) /sbin/request-key assumes the authority associated with key U. + 5) /sbin/request-key assumes the authority associated with key U. - (6) /sbin/request-key execs an appropriate program to perform the actual + 6) /sbin/request-key execs an appropriate program to perform the actual instantiation. - (7) The program may want to access another key from A's context (say a + 7) The program may want to access another key from A's context (say a Kerberos TGT key). It just requests the appropriate key, and the keyring search notes that the session keyring has auth key V in its bottom level. @@ -106,15 +105,15 @@ A request proceeds in the following manner: UID, GID, groups and security info of process A as if it was process A, and come up with key W. - (8) The program then does what it must to get the data with which to + 8) The program then does what it must to get the data with which to instantiate key U, using key W as a reference (perhaps it contacts a Kerberos server using the TGT) and then instantiates key U. - (9) Upon instantiating key U, auth key V is automatically revoked so that it + 9) Upon instantiating key U, auth key V is automatically revoked so that it may not be used again. -(10) The program then exits 0 and request_key() deletes key V and returns key - U to the caller. + 10) The program then exits 0 and request_key() deletes key V and returns key + U to the caller. This also extends further. If key W (step 7 above) didn't exist, key W would be created uninstantiated, another auth key (X) would be created (as per step @@ -127,8 +126,7 @@ This is because process A's keyrings can't simply be attached to of them, and (b) it requires the same UID/GID/Groups all the way through. -==================================== -NEGATIVE INSTANTIATION AND REJECTION +Negative Instantiation And Rejection ==================================== Rather than instantiating a key, it is possible for the possessor of an @@ -145,23 +143,22 @@ signal, the key under construction will be automatically negatively instantiated for a short amount of time. -==================== -THE SEARCH ALGORITHM +The Search Algorithm ==================== A search of any particular keyring proceeds in the following fashion: - (1) When the key management code searches for a key (keyring_search_aux) it + 1) When the key management code searches for a key (keyring_search_aux) it firstly calls key_permission(SEARCH) on the keyring it's starting with, if this denies permission, it doesn't search further. - (2) It considers all the non-keyring keys within that keyring and, if any key + 2) It considers all the non-keyring keys within that keyring and, if any key matches the criteria specified, calls key_permission(SEARCH) on it to see if the key is allowed to be found. If it is, that key is returned; if not, the search continues, and the error code is retained if of higher priority than the one currently set. - (3) It then considers all the keyring-type keys in the keyring it's currently + 3) It then considers all the keyring-type keys in the keyring it's currently searching. It calls key_permission(SEARCH) on each keyring, and if this grants permission, it recurses, executing steps (2) and (3) on that keyring. @@ -173,20 +170,20 @@ returned. When search_process_keyrings() is invoked, it performs the following searches until one succeeds: - (1) If extant, the process's thread keyring is searched. + 1) If extant, the process's thread keyring is searched. - (2) If extant, the process's process keyring is searched. + 2) If extant, the process's process keyring is searched. - (3) The process's session keyring is searched. + 3) The process's session keyring is searched. - (4) If the process has assumed the authority associated with a request_key() + 4) If the process has assumed the authority associated with a request_key() authorisation key then: - (a) If extant, the calling process's thread keyring is searched. + a) If extant, the calling process's thread keyring is searched. - (b) If extant, the calling process's process keyring is searched. + b) If extant, the calling process's process keyring is searched. - (c) The calling process's session keyring is searched. + c) The calling process's session keyring is searched. The moment one succeeds, all pending errors are discarded and the found key is returned. @@ -194,7 +191,7 @@ returned. Only if all these fail does the whole thing fail with the highest priority error. Note that several errors may have come from LSM. -The error priority is: +The error priority is:: EKEYREVOKED > EKEYEXPIRED > ENOKEY diff --git a/Documentation/security/keys-trusted-encrypted.txt b/Documentation/security/keys/trusted-encrypted.rst index b20a993a32af..7b503831bdea 100644 --- a/Documentation/security/keys-trusted-encrypted.txt +++ b/Documentation/security/keys/trusted-encrypted.rst @@ -1,4 +1,6 @@ - Trusted and Encrypted Keys +========================== +Trusted and Encrypted Keys +========================== Trusted and Encrypted Keys are two new key types added to the existing kernel key ring service. Both of these new types are variable length symmetric keys, @@ -20,7 +22,8 @@ By default, trusted keys are sealed under the SRK, which has the default authorization value (20 zeros). This can be set at takeownership time with the trouser's utility: "tpm_takeownership -u -z". -Usage: +Usage:: + keyctl add trusted name "new keylen [options]" ring keyctl add trusted name "load hex_blob [pcrlock=pcrnum]" ring keyctl update key "update [options]" @@ -64,19 +67,22 @@ The decrypted portion of encrypted keys can contain either a simple symmetric key or a more complex structure. The format of the more complex structure is application specific, which is identified by 'format'. -Usage: +Usage:: + keyctl add encrypted name "new [format] key-type:master-key-name keylen" ring keyctl add encrypted name "load hex_blob" ring keyctl update keyid "update key-type:master-key-name" -format:= 'default | ecryptfs' -key-type:= 'trusted' | 'user' +Where:: + + format:= 'default | ecryptfs' + key-type:= 'trusted' | 'user' Examples of trusted and encrypted key usage: -Create and save a trusted key named "kmk" of length 32 bytes: +Create and save a trusted key named "kmk" of length 32 bytes:: $ keyctl add trusted kmk "new 32" @u 440502848 @@ -99,7 +105,7 @@ Create and save a trusted key named "kmk" of length 32 bytes: $ keyctl pipe 440502848 > kmk.blob -Load a trusted key from the saved blob: +Load a trusted key from the saved blob:: $ keyctl add trusted kmk "load `cat kmk.blob`" @u 268728824 @@ -114,7 +120,7 @@ Load a trusted key from the saved blob: f1f8fff03ad0acb083725535636addb08d73dedb9832da198081e5deae84bfaf0409c22b e4a8aea2b607ec96931e6f4d4fe563ba -Reseal a trusted key under new pcr values: +Reseal a trusted key under new pcr values:: $ keyctl update 268728824 "update pcrinfo=`cat pcr.blob`" $ keyctl print 268728824 @@ -135,11 +141,13 @@ compromised by a user level problem, and when sealed to specific boot PCR values, protects against boot and offline attacks. Create and save an encrypted key "evm" using the above trusted key "kmk": -option 1: omitting 'format' +option 1: omitting 'format':: + $ keyctl add encrypted evm "new trusted:kmk 32" @u 159771175 -option 2: explicitly defining 'format' as 'default' +option 2: explicitly defining 'format' as 'default':: + $ keyctl add encrypted evm "new default trusted:kmk 32" @u 159771175 @@ -150,7 +158,7 @@ option 2: explicitly defining 'format' as 'default' $ keyctl pipe 159771175 > evm.blob -Load an encrypted key "evm" from saved blob: +Load an encrypted key "evm" from saved blob:: $ keyctl add encrypted evm "load `cat evm.blob`" @u 831684262 @@ -164,4 +172,4 @@ Other uses for trusted and encrypted keys, such as for disk and file encryption are anticipated. In particular the new format 'ecryptfs' has been defined in in order to use encrypted keys to mount an eCryptfs filesystem. More details about the usage can be found in the file -'Documentation/security/keys-ecryptfs.txt'. +``Documentation/security/keys-ecryptfs.txt``. diff --git a/Documentation/security/self-protection.txt b/Documentation/security/self-protection.rst index 141acfebe6ef..60c8bd8b77bf 100644 --- a/Documentation/security/self-protection.txt +++ b/Documentation/security/self-protection.rst @@ -1,4 +1,6 @@ -# Kernel Self-Protection +====================== +Kernel Self-Protection +====================== Kernel self-protection is the design and implementation of systems and structures within the Linux kernel to protect against security flaws in @@ -26,7 +28,8 @@ mentioning them, since these aspects need to be explored, dealt with, and/or accepted. -## Attack Surface Reduction +Attack Surface Reduction +======================== The most fundamental defense against security exploits is to reduce the areas of the kernel that can be used to redirect execution. This ranges @@ -34,13 +37,15 @@ from limiting the exposed APIs available to userspace, making in-kernel APIs hard to use incorrectly, minimizing the areas of writable kernel memory, etc. -### Strict kernel memory permissions +Strict kernel memory permissions +-------------------------------- When all of kernel memory is writable, it becomes trivial for attacks to redirect execution flow. To reduce the availability of these targets the kernel needs to protect its memory with a tight set of permissions. -#### Executable code and read-only data must not be writable +Executable code and read-only data must not be writable +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Any areas of the kernel with executable memory must not be writable. While this obviously includes the kernel text itself, we must consider @@ -51,18 +56,19 @@ kernel, they are implemented in a way where the memory is temporarily made writable during the update, and then returned to the original permissions.) -In support of this are CONFIG_STRICT_KERNEL_RWX and -CONFIG_STRICT_MODULE_RWX, which seek to make sure that code is not +In support of this are ``CONFIG_STRICT_KERNEL_RWX`` and +``CONFIG_STRICT_MODULE_RWX``, which seek to make sure that code is not writable, data is not executable, and read-only data is neither writable nor executable. Most architectures have these options on by default and not user selectable. For some architectures like arm that wish to have these be selectable, the architecture Kconfig can select ARCH_OPTIONAL_KERNEL_RWX to enable -a Kconfig prompt. CONFIG_ARCH_OPTIONAL_KERNEL_RWX_DEFAULT determines +a Kconfig prompt. ``CONFIG_ARCH_OPTIONAL_KERNEL_RWX_DEFAULT`` determines the default setting when ARCH_OPTIONAL_KERNEL_RWX is enabled. -#### Function pointers and sensitive variables must not be writable +Function pointers and sensitive variables must not be writable +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Vast areas of kernel memory contain function pointers that are looked up by the kernel and used to continue execution (e.g. descriptor/vector @@ -74,8 +80,8 @@ so that they live in the .rodata section instead of the .data section of the kernel, gaining the protection of the kernel's strict memory permissions as described above. -For variables that are initialized once at __init time, these can -be marked with the (new and under development) __ro_after_init +For variables that are initialized once at ``__init`` time, these can +be marked with the (new and under development) ``__ro_after_init`` attribute. What remains are variables that are updated rarely (e.g. GDT). These @@ -85,7 +91,8 @@ of their lifetime read-only. (For example, when being updated, only the CPU thread performing the update would be given uninterruptible write access to the memory.) -#### Segregation of kernel memory from userspace memory +Segregation of kernel memory from userspace memory +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The kernel must never execute userspace memory. The kernel must also never access userspace memory without explicit expectation to do so. These @@ -95,10 +102,11 @@ By blocking userspace memory in this way, execution and data parsing cannot be passed to trivially-controlled userspace memory, forcing attacks to operate entirely in kernel memory. -### Reduced access to syscalls +Reduced access to syscalls +-------------------------- One trivial way to eliminate many syscalls for 64-bit systems is building -without CONFIG_COMPAT. However, this is rarely a feasible scenario. +without ``CONFIG_COMPAT``. However, this is rarely a feasible scenario. The "seccomp" system provides an opt-in feature made available to userspace, which provides a way to reduce the number of kernel entry @@ -112,7 +120,8 @@ to trusted processes. This would keep the scope of kernel entry points restricted to the more regular set of normally available to unprivileged userspace. -### Restricting access to kernel modules +Restricting access to kernel modules +------------------------------------ The kernel should never allow an unprivileged user the ability to load specific kernel modules, since that would provide a facility to @@ -127,11 +136,12 @@ for debate in some scenarios.) To protect against even privileged users, systems may need to either disable module loading entirely (e.g. monolithic kernel builds or modules_disabled sysctl), or provide signed modules (e.g. -CONFIG_MODULE_SIG_FORCE, or dm-crypt with LoadPin), to keep from having +``CONFIG_MODULE_SIG_FORCE``, or dm-crypt with LoadPin), to keep from having root load arbitrary kernel code via the module loader interface. -## Memory integrity +Memory integrity +================ There are many memory structures in the kernel that are regularly abused to gain execution control during an attack, By far the most commonly @@ -139,16 +149,18 @@ understood is that of the stack buffer overflow in which the return address stored on the stack is overwritten. Many other examples of this kind of attack exist, and protections exist to defend against them. -### Stack buffer overflow +Stack buffer overflow +--------------------- The classic stack buffer overflow involves writing past the expected end of a variable stored on the stack, ultimately writing a controlled value to the stack frame's stored return address. The most widely used defense is the presence of a stack canary between the stack variables and the -return address (CONFIG_CC_STACKPROTECTOR), which is verified just before +return address (``CONFIG_CC_STACKPROTECTOR``), which is verified just before the function returns. Other defenses include things like shadow stacks. -### Stack depth overflow +Stack depth overflow +-------------------- A less well understood attack is using a bug that triggers the kernel to consume stack memory with deep function calls or large stack @@ -158,27 +170,31 @@ important changes need to be made for better protections: moving the sensitive thread_info structure elsewhere, and adding a faulting memory hole at the bottom of the stack to catch these overflows. -### Heap memory integrity +Heap memory integrity +--------------------- The structures used to track heap free lists can be sanity-checked during allocation and freeing to make sure they aren't being used to manipulate other memory areas. -### Counter integrity +Counter integrity +----------------- Many places in the kernel use atomic counters to track object references or perform similar lifetime management. When these counters can be made to wrap (over or under) this traditionally exposes a use-after-free flaw. By trapping atomic wrapping, this class of bug vanishes. -### Size calculation overflow detection +Size calculation overflow detection +----------------------------------- Similar to counter overflow, integer overflows (usually size calculations) need to be detected at runtime to kill this class of bug, which traditionally leads to being able to write past the end of kernel buffers. -## Statistical defenses +Probabilistic defenses +====================== While many protections can be considered deterministic (e.g. read-only memory cannot be written to), some protections provide only statistical @@ -186,7 +202,8 @@ defense, in that an attack must gather enough information about a running system to overcome the defense. While not perfect, these do provide meaningful defenses. -### Canaries, blinding, and other secrets +Canaries, blinding, and other secrets +------------------------------------- It should be noted that things like the stack canary discussed earlier are technically statistical defenses, since they rely on a secret value, @@ -201,7 +218,8 @@ It is critical that the secret values used must be separate (e.g. different canary per stack) and high entropy (e.g. is the RNG actually working?) in order to maximize their success. -### Kernel Address Space Layout Randomization (KASLR) +Kernel Address Space Layout Randomization (KASLR) +------------------------------------------------- Since the location of kernel memory is almost always instrumental in mounting a successful attack, making the location non-deterministic @@ -209,22 +227,25 @@ raises the difficulty of an exploit. (Note that this in turn makes the value of information exposures higher, since they may be used to discover desired memory locations.) -#### Text and module base +Text and module base +~~~~~~~~~~~~~~~~~~~~ By relocating the physical and virtual base address of the kernel at -boot-time (CONFIG_RANDOMIZE_BASE), attacks needing kernel code will be +boot-time (``CONFIG_RANDOMIZE_BASE``), attacks needing kernel code will be frustrated. Additionally, offsetting the module loading base address means that even systems that load the same set of modules in the same order every boot will not share a common base address with the rest of the kernel text. -#### Stack base +Stack base +~~~~~~~~~~ If the base address of the kernel stack is not the same between processes, or even not the same between syscalls, targets on or beyond the stack become more difficult to locate. -#### Dynamic memory base +Dynamic memory base +~~~~~~~~~~~~~~~~~~~ Much of the kernel's dynamic memory (e.g. kmalloc, vmalloc, etc) ends up being relatively deterministic in layout due to the order of early-boot @@ -232,7 +253,8 @@ initializations. If the base address of these areas is not the same between boots, targeting them is frustrated, requiring an information exposure specific to the region. -#### Structure layout +Structure layout +~~~~~~~~~~~~~~~~ By performing a per-build randomization of the layout of sensitive structures, attacks must either be tuned to known kernel builds or expose @@ -240,26 +262,30 @@ enough kernel memory to determine structure layouts before manipulating them. -## Preventing Information Exposures +Preventing Information Exposures +================================ Since the locations of sensitive structures are the primary target for attacks, it is important to defend against exposure of both kernel memory addresses and kernel memory contents (since they may contain kernel addresses or other sensitive things like canary values). -### Unique identifiers +Unique identifiers +------------------ Kernel memory addresses must never be used as identifiers exposed to userspace. Instead, use an atomic counter, an idr, or similar unique identifier. -### Memory initialization +Memory initialization +--------------------- Memory copied to userspace must always be fully initialized. If not explicitly memset(), this will require changes to the compiler to make sure structure holes are cleared. -### Memory poisoning +Memory poisoning +---------------- When releasing memory, it is best to poison the contents (clear stack on syscall return, wipe heap memory on a free), to avoid reuse attacks that @@ -267,9 +293,10 @@ rely on the old contents of memory. This frustrates many uninitialized variable attacks, stack content exposures, heap content exposures, and use-after-free attacks. -### Destination tracking +Destination tracking +-------------------- To help kill classes of bugs that result in kernel addresses being written to userspace, the destination of writes needs to be tracked. If -the buffer is destined for userspace (e.g. seq_file backed /proc files), +the buffer is destined for userspace (e.g. seq_file backed ``/proc`` files), it should automatically censor sensitive values. diff --git a/Documentation/serial/n_gsm.txt b/Documentation/serial/n_gsm.txt index a5d91126a8f7..875361bb7cb4 100644 --- a/Documentation/serial/n_gsm.txt +++ b/Documentation/serial/n_gsm.txt @@ -77,6 +77,13 @@ for example, it's possible : 6- first close all virtual ports before closing the physical port. +Note that after closing the physical port the modem is still in multiplexing +mode. This may prevent a successful re-opening of the port later. To avoid +this situation either reset the modem if your hardware allows that or send +a disconnect command frame manually before initializing the multiplexing mode +for the second time. The byte sequence for the disconnect command frame is: +0xf9, 0x03, 0xef, 0x03, 0xc3, 0x16, 0xf9. + Additional Documentation ------------------------ More practical details on the protocol and how it's supported by industrial diff --git a/Documentation/sh/conf.py b/Documentation/sh/conf.py new file mode 100644 index 000000000000..1eb684a13ac8 --- /dev/null +++ b/Documentation/sh/conf.py @@ -0,0 +1,10 @@ +# -*- coding: utf-8; mode: python -*- + +project = "SuperH architecture implementation manual" + +tags.add("subproject") + +latex_documents = [ + ('index', 'sh.tex', project, + 'The kernel development community', 'manual'), +] diff --git a/Documentation/sh/index.rst b/Documentation/sh/index.rst new file mode 100644 index 000000000000..bc8db7ba894a --- /dev/null +++ b/Documentation/sh/index.rst @@ -0,0 +1,59 @@ +======================= +SuperH Interfaces Guide +======================= + +:Author: Paul Mundt + +Memory Management +================= + +SH-4 +---- + +Store Queue API +~~~~~~~~~~~~~~~ + +.. kernel-doc:: arch/sh/kernel/cpu/sh4/sq.c + :export: + +SH-5 +---- + +TLB Interfaces +~~~~~~~~~~~~~~ + +.. kernel-doc:: arch/sh/mm/tlb-sh5.c + :internal: + +.. kernel-doc:: arch/sh/include/asm/tlb_64.h + :internal: + +Machine Specific Interfaces +=========================== + +mach-dreamcast +-------------- + +.. kernel-doc:: arch/sh/boards/mach-dreamcast/rtc.c + :internal: + +mach-x3proto +------------ + +.. kernel-doc:: arch/sh/boards/mach-x3proto/ilsel.c + :export: + +Busses +====== + +SuperHyway +---------- + +.. kernel-doc:: drivers/sh/superhyway/superhyway.c + :export: + +Maple +----- + +.. kernel-doc:: drivers/sh/maple/maple.c + :export: diff --git a/Documentation/sound/conf.py b/Documentation/sound/conf.py new file mode 100644 index 000000000000..3f1fc5e74e7b --- /dev/null +++ b/Documentation/sound/conf.py @@ -0,0 +1,10 @@ +# -*- coding: utf-8; mode: python -*- + +project = "Linux Sound Subsystem Documentation" + +tags.add("subproject") + +latex_documents = [ + ('index', 'sound.tex', project, + 'The kernel development community', 'manual'), +] diff --git a/Documentation/sound/hd-audio/models.rst b/Documentation/sound/hd-audio/models.rst index 5338673c88d9..773d2bfacc6c 100644 --- a/Documentation/sound/hd-audio/models.rst +++ b/Documentation/sound/hd-audio/models.rst @@ -16,6 +16,8 @@ ALC880 6-jack in back, 2-jack in front 6stack-digout 6-jack with a SPDIF out +6stack-automute + 6-jack with headphone jack detection ALC260 ====== @@ -62,6 +64,8 @@ lenovo-dock Enables docking station I/O for some Lenovos hp-gpio-led GPIO LED support on HP laptops +hp-dock-gpio-mic1-led + HP dock with mic LED support dell-headset-multi Headset jack, which can also be used as mic-in dell-headset-dock @@ -72,6 +76,12 @@ alc283-sense-combo Combo jack sensing on ALC283 tpt440-dock Pin configs for Lenovo Thinkpad Dock support +tpt440 + Lenovo Thinkpad T440s setup +tpt460 + Lenovo Thinkpad T460/560 setup +dual-codecs + Lenovo laptops with dual codecs ALC66x/67x/892 ============== @@ -97,6 +107,8 @@ inv-dmic Inverted internal mic workaround dell-headset-multi Headset jack, which can also be used as mic-in +dual-codecs + Lenovo laptops with dual codecs ALC680 ====== @@ -114,6 +126,8 @@ inv-dmic Inverted internal mic workaround no-primary-hp VAIO Z/VGC-LN51JGB workaround (for fixed speaker DAC) +dual-codecs + ALC1220 dual codecs for Gaming mobos ALC861/660 ========== @@ -206,65 +220,47 @@ auto Conexant 5045 ============= -laptop-hpsense - Laptop with HP sense (old model laptop) -laptop-micsense - Laptop with Mic sense (old model fujitsu) -laptop-hpmicsense - Laptop with HP and Mic senses -benq - Benq R55E -laptop-hp530 - HP 530 laptop -test - for testing/debugging purpose, almost all controls can be - adjusted. Appearing only when compiled with $CONFIG_SND_DEBUG=y +cap-mix-amp + Fix max input level on mixer widget +toshiba-p105 + Toshiba P105 quirk +hp-530 + HP 530 quirk Conexant 5047 ============= -laptop - Basic Laptop config -laptop-hp - Laptop config for some HP models (subdevice 30A5) -laptop-eapd - Laptop config with EAPD support -test - for testing/debugging purpose, almost all controls can be - adjusted. Appearing only when compiled with $CONFIG_SND_DEBUG=y +cap-mix-amp + Fix max input level on mixer widget Conexant 5051 ============= -laptop - Basic Laptop config (default) -hp - HP Spartan laptop -hp-dv6736 - HP dv6736 -hp-f700 - HP Compaq Presario F700 -ideapad - Lenovo IdeaPad laptop -toshiba - Toshiba Satellite M300 +lenovo-x200 + Lenovo X200 quirk Conexant 5066 ============= -laptop - Basic Laptop config (default) -hp-laptop - HP laptops, e g G60 -asus - Asus K52JU, Lenovo G560 -dell-laptop - Dell laptops -dell-vostro - Dell Vostro -olpc-xo-1_5 - OLPC XO 1.5 -ideapad - Lenovo IdeaPad U150 +stereo-dmic + Workaround for inverted stereo digital mic +gpio1 + Enable GPIO1 pin +headphone-mic-pin + Enable headphone mic NID 0x18 without detection +tp410 + Thinkpad T400 & co quirks thinkpad - Lenovo Thinkpad + Thinkpad mute/mic LED quirk +lemote-a1004 + Lemote A1004 quirk +lemote-a1205 + Lemote A1205 quirk +olpc-xo + OLPC XO quirk +mute-led-eapd + Mute LED control via EAPD +hp-dock + HP dock support +mute-led-gpio + Mute LED control via GPIO STAC9200 ======== @@ -444,6 +440,8 @@ dell-eq Dell desktops/laptops alienware Alienware M17x +asus-mobo + Pin configs for ASUS mobo with 5.1/SPDIF out auto BIOS setup (default) @@ -477,6 +475,8 @@ hp-envy-ts-bass Pin fixup for HP Envy TS bass speaker (NID 0x10) hp-bnb13-eq Hardware equalizer setup for HP laptops +hp-envy-ts-bass + HP Envy TS bass support auto BIOS setup (default) @@ -496,10 +496,22 @@ auto Cirrus Logic CS4206/4207 ======================== +mbp53 + MacBook Pro 5,3 mbp55 MacBook Pro 5,5 imac27 IMac 27 Inch +imac27_122 + iMac 12,2 +apple + Generic Apple quirk +mbp101 + MacBookPro 10,1 +mbp81 + MacBookPro 8,1 +mba42 + MacBookAir 4,2 auto BIOS setup (default) @@ -509,6 +521,10 @@ mba6 MacBook Air 6,1 and 6,2 gpio0 Enable GPIO 0 amp +mbp11 + MacBookPro 11,2 +macmini + MacMini 7,1 auto BIOS setup (default) diff --git a/Documentation/sphinx/convert_template.sed b/Documentation/sphinx/convert_template.sed deleted file mode 100644 index c1503fcca4ec..000000000000 --- a/Documentation/sphinx/convert_template.sed +++ /dev/null @@ -1,18 +0,0 @@ -# -# Pandoc doesn't grok <function> or <structname>, so convert them -# ahead of time. -# -# Use the following escapes to pass through pandoc: -# $bq = "`" -# $lt = "<" -# $gt = ">" -# -s%<function>\([^<(]\+\)()</function>%:c:func:$bq\1()$bq%g -s%<function>\([^<(]\+\)</function>%:c:func:$bq\1()$bq%g -s%<structname>struct *\([^<]\+\)</structname>%:c:type:$bqstruct \1 $lt\1$gt$bq%g -s%struct <structname>\([^<]\+\)</structname>%:c:type:$bqstruct \1 $lt\1$gt$bq%g -s%<structname>\([^<]\+\)</structname>%:c:type:$bqstruct \1 $lt\1$gt$bq%g -# -# Wrap docproc directives in para and code blocks. -# -s%^\(!.*\)$%<para><code>DOCPROC: \1</code></para>% diff --git a/Documentation/sphinx/post_convert.sed b/Documentation/sphinx/post_convert.sed deleted file mode 100644 index 392770bac53b..000000000000 --- a/Documentation/sphinx/post_convert.sed +++ /dev/null @@ -1,23 +0,0 @@ -# -# Unescape. -# -s/$bq/`/g -s/$lt/</g -s/$gt/>/g -# -# pandoc thinks that both "_" needs to be escaped. Remove the extra -# backslashes. -# -s/\\_/_/g -# -# Unwrap docproc directives. -# -s/^``DOCPROC: !E\(.*\)``$/.. kernel-doc:: \1\n :export:/ -s/^``DOCPROC: !I\(.*\)``$/.. kernel-doc:: \1\n :internal:/ -s/^``DOCPROC: !F\([^ ]*\) \(.*\)``$/.. kernel-doc:: \1\n :functions: \2/ -s/^``DOCPROC: !P\([^ ]*\) \(.*\)``$/.. kernel-doc:: \1\n :doc: \2/ -s/^``DOCPROC: \(!.*\)``$/.. WARNING: DOCPROC directive not supported: \1/ -# -# Trim trailing whitespace. -# -s/[[:space:]]*$// diff --git a/Documentation/sphinx/tmplcvt b/Documentation/sphinx/tmplcvt deleted file mode 100755 index 6848f0a26fa5..000000000000 --- a/Documentation/sphinx/tmplcvt +++ /dev/null @@ -1,28 +0,0 @@ -#!/bin/bash -# -# Convert a template file into something like RST -# -# fix <function> -# feed to pandoc -# fix \_ -# title line? -# -set -eu - -if [ "$#" != "2" ]; then - echo "$0 <docbook file> <rst file>" - exit -fi - -DIR=$(dirname $0) - -in=$1 -rst=$2 -tmp=$rst.tmp - -cp $in $tmp -sed --in-place -f $DIR/convert_template.sed $tmp -pandoc -s -S -f docbook -t rst -o $rst $tmp -sed --in-place -f $DIR/post_convert.sed $rst -rm $tmp -echo "book writen to $rst" diff --git a/Documentation/spi/spi-summary b/Documentation/spi/spi-summary index d1824b399b2d..1721c1b570c3 100644 --- a/Documentation/spi/spi-summary +++ b/Documentation/spi/spi-summary @@ -62,8 +62,8 @@ chips described as using "three wire" signaling: SCK, data, nCSx. (That data line is sometimes called MOMI or SISO.) Microcontrollers often support both master and slave sides of the SPI -protocol. This document (and Linux) currently only supports the master -side of SPI interactions. +protocol. This document (and Linux) supports both the master and slave +sides of SPI interactions. Who uses it? On what kinds of systems? @@ -154,9 +154,8 @@ control audio interfaces, present touchscreen sensors as input interfaces, or monitor temperature and voltage levels during industrial processing. And those might all be sharing the same controller driver. -A "struct spi_device" encapsulates the master-side interface between -those two types of driver. At this writing, Linux has no slave side -programming interface. +A "struct spi_device" encapsulates the controller-side interface between +those two types of drivers. There is a minimal core of SPI programming interfaces, focussing on using the driver model to connect controller and protocol drivers using @@ -177,10 +176,24 @@ shows up in sysfs in several locations: /sys/bus/spi/drivers/D ... driver for one or more spi*.* devices /sys/class/spi_master/spiB ... symlink (or actual device node) to - a logical node which could hold class related state for the - controller managing bus "B". All spiB.* devices share one + a logical node which could hold class related state for the SPI + master controller managing bus "B". All spiB.* devices share one physical SPI bus segment, with SCLK, MOSI, and MISO. + /sys/devices/.../CTLR/slave ... virtual file for (un)registering the + slave device for an SPI slave controller. + Writing the driver name of an SPI slave handler to this file + registers the slave device; writing "(null)" unregisters the slave + device. + Reading from this file shows the name of the slave device ("(null)" + if not registered). + + /sys/class/spi_slave/spiB ... symlink (or actual device node) to + a logical node which could hold class related state for the SPI + slave controller on bus "B". When registered, a single spiB.* + device is present here, possible sharing the physical SPI bus + segment with other SPI slave devices. + Note that the actual location of the controller's class state depends on whether you enabled CONFIG_SYSFS_DEPRECATED or not. At this time, the only class-specific state is the bus number ("B" in "spiB"), so diff --git a/Documentation/timers/NO_HZ.txt b/Documentation/timers/NO_HZ.txt index 6eaf576294f3..2dcaf9adb7a7 100644 --- a/Documentation/timers/NO_HZ.txt +++ b/Documentation/timers/NO_HZ.txt @@ -194,32 +194,9 @@ that the RCU callbacks are processed in a timely fashion. Another approach is to offload RCU callback processing to "rcuo" kthreads using the CONFIG_RCU_NOCB_CPU=y Kconfig option. The specific CPUs to -offload may be selected via several methods: - -1. One of three mutually exclusive Kconfig options specify a - build-time default for the CPUs to offload: - - a. The CONFIG_RCU_NOCB_CPU_NONE=y Kconfig option results in - no CPUs being offloaded. - - b. The CONFIG_RCU_NOCB_CPU_ZERO=y Kconfig option causes - CPU 0 to be offloaded. - - c. The CONFIG_RCU_NOCB_CPU_ALL=y Kconfig option causes all - CPUs to be offloaded. Note that the callbacks will be - offloaded to "rcuo" kthreads, and that those kthreads - will in fact run on some CPU. However, this approach - gives fine-grained control on exactly which CPUs the - callbacks run on, along with their scheduling priority - (including the default of SCHED_OTHER), and it further - allows this control to be varied dynamically at runtime. - -2. The "rcu_nocbs=" kernel boot parameter, which takes a comma-separated - list of CPUs and CPU ranges, for example, "1,3-5" selects CPUs 1, - 3, 4, and 5. The specified CPUs will be offloaded in addition to - any CPUs specified as offloaded by CONFIG_RCU_NOCB_CPU_ZERO=y or - CONFIG_RCU_NOCB_CPU_ALL=y. This means that the "rcu_nocbs=" boot - parameter has no effect for kernels built with RCU_NOCB_CPU_ALL=y. +offload may be selected using The "rcu_nocbs=" kernel boot parameter, +which takes a comma-separated list of CPUs and CPU ranges, for example, +"1,3-5" selects CPUs 1, 3, 4, and 5. The offloaded CPUs will never queue RCU callbacks, and therefore RCU never prevents offloaded CPUs from entering either dyntick-idle mode diff --git a/Documentation/trace/coresight-cpu-debug.txt b/Documentation/trace/coresight-cpu-debug.txt new file mode 100644 index 000000000000..b3da1f90b861 --- /dev/null +++ b/Documentation/trace/coresight-cpu-debug.txt @@ -0,0 +1,175 @@ + Coresight CPU Debug Module + ========================== + + Author: Leo Yan <leo.yan@linaro.org> + Date: April 5th, 2017 + +Introduction +------------ + +Coresight CPU debug module is defined in ARMv8-a architecture reference manual +(ARM DDI 0487A.k) Chapter 'Part H: External debug', the CPU can integrate +debug module and it is mainly used for two modes: self-hosted debug and +external debug. Usually the external debug mode is well known as the external +debugger connects with SoC from JTAG port; on the other hand the program can +explore debugging method which rely on self-hosted debug mode, this document +is to focus on this part. + +The debug module provides sample-based profiling extension, which can be used +to sample CPU program counter, secure state and exception level, etc; usually +every CPU has one dedicated debug module to be connected. Based on self-hosted +debug mechanism, Linux kernel can access these related registers from mmio +region when the kernel panic happens. The callback notifier for kernel panic +will dump related registers for every CPU; finally this is good for assistant +analysis for panic. + + +Implementation +-------------- + +- During driver registration, it uses EDDEVID and EDDEVID1 - two device ID + registers to decide if sample-based profiling is implemented or not. On some + platforms this hardware feature is fully or partially implemented; and if + this feature is not supported then registration will fail. + +- At the time this documentation was written, the debug driver mainly relies on + information gathered by the kernel panic callback notifier from three + sampling registers: EDPCSR, EDVIDSR and EDCIDSR: from EDPCSR we can get + program counter; EDVIDSR has information for secure state, exception level, + bit width, etc; EDCIDSR is context ID value which contains the sampled value + of CONTEXTIDR_EL1. + +- The driver supports a CPU running in either AArch64 or AArch32 mode. The + registers naming convention is a bit different between them, AArch64 uses + 'ED' for register prefix (ARM DDI 0487A.k, chapter H9.1) and AArch32 uses + 'DBG' as prefix (ARM DDI 0487A.k, chapter G5.1). The driver is unified to + use AArch64 naming convention. + +- ARMv8-a (ARM DDI 0487A.k) and ARMv7-a (ARM DDI 0406C.b) have different + register bits definition. So the driver consolidates two difference: + + If PCSROffset=0b0000, on ARMv8-a the feature of EDPCSR is not implemented; + but ARMv7-a defines "PCSR samples are offset by a value that depends on the + instruction set state". For ARMv7-a, the driver checks furthermore if CPU + runs with ARM or thumb instruction set and calibrate PCSR value, the + detailed description for offset is in ARMv7-a ARM (ARM DDI 0406C.b) chapter + C11.11.34 "DBGPCSR, Program Counter Sampling Register". + + If PCSROffset=0b0010, ARMv8-a defines "EDPCSR implemented, and samples have + no offset applied and do not sample the instruction set state in AArch32 + state". So on ARMv8 if EDDEVID1.PCSROffset is 0b0010 and the CPU operates + in AArch32 state, EDPCSR is not sampled; when the CPU operates in AArch64 + state EDPCSR is sampled and no offset are applied. + + +Clock and power domain +---------------------- + +Before accessing debug registers, we should ensure the clock and power domain +have been enabled properly. In ARMv8-a ARM (ARM DDI 0487A.k) chapter 'H9.1 +Debug registers', the debug registers are spread into two domains: the debug +domain and the CPU domain. + + +---------------+ + | | + | | + +----------+--+ | + dbg_clock -->| |**| |<-- cpu_clock + | Debug |**| CPU | + dbg_power_domain -->| |**| |<-- cpu_power_domain + +----------+--+ | + | | + | | + +---------------+ + +For debug domain, the user uses DT binding "clocks" and "power-domains" to +specify the corresponding clock source and power supply for the debug logic. +The driver calls the pm_runtime_{put|get} operations as needed to handle the +debug power domain. + +For CPU domain, the different SoC designs have different power management +schemes and finally this heavily impacts external debug module. So we can +divide into below cases: + +- On systems with a sane power controller which can behave correctly with + respect to CPU power domain, the CPU power domain can be controlled by + register EDPRCR in driver. The driver firstly writes bit EDPRCR.COREPURQ + to power up the CPU, and then writes bit EDPRCR.CORENPDRQ for emulation + of CPU power down. As result, this can ensure the CPU power domain is + powered on properly during the period when access debug related registers; + +- Some designs will power down an entire cluster if all CPUs on the cluster + are powered down - including the parts of the debug registers that should + remain powered in the debug power domain. The bits in EDPRCR are not + respected in these cases, so these designs do not support debug over + power down in the way that the CoreSight / Debug designers anticipated. + This means that even checking EDPRSR has the potential to cause a bus hang + if the target register is unpowered. + + In this case, accessing to the debug registers while they are not powered + is a recipe for disaster; so we need preventing CPU low power states at boot + time or when user enable module at the run time. Please see chapter + "How to use the module" for detailed usage info for this. + + +Device Tree Bindings +-------------------- + +See Documentation/devicetree/bindings/arm/coresight-cpu-debug.txt for details. + + +How to use the module +--------------------- + +If you want to enable debugging functionality at boot time, you can add +"coresight_cpu_debug.enable=1" to the kernel command line parameter. + +The driver also can work as module, so can enable the debugging when insmod +module: +# insmod coresight_cpu_debug.ko debug=1 + +When boot time or insmod module you have not enabled the debugging, the driver +uses the debugfs file system to provide a knob to dynamically enable or disable +debugging: + +To enable it, write a '1' into /sys/kernel/debug/coresight_cpu_debug/enable: +# echo 1 > /sys/kernel/debug/coresight_cpu_debug/enable + +To disable it, write a '0' into /sys/kernel/debug/coresight_cpu_debug/enable: +# echo 0 > /sys/kernel/debug/coresight_cpu_debug/enable + +As explained in chapter "Clock and power domain", if you are working on one +platform which has idle states to power off debug logic and the power +controller cannot work well for the request from EDPRCR, then you should +firstly constraint CPU idle states before enable CPU debugging feature; so can +ensure the accessing to debug logic. + +If you want to limit idle states at boot time, you can use "nohlt" or +"cpuidle.off=1" in the kernel command line. + +At the runtime you can disable idle states with below methods: + +Set latency request to /dev/cpu_dma_latency to disable all CPUs specific idle +states (if latency = 0uS then disable all idle states): +# echo "what_ever_latency_you_need_in_uS" > /dev/cpu_dma_latency + +Disable specific CPU's specific idle state: +# echo 1 > /sys/devices/system/cpu/cpu$cpu/cpuidle/state$state/disable + + +Output format +------------- + +Here is an example of the debugging output format: + +ARM external debug module: +coresight-cpu-debug 850000.debug: CPU[0]: +coresight-cpu-debug 850000.debug: EDPRSR: 00000001 (Power:On DLK:Unlock) +coresight-cpu-debug 850000.debug: EDPCSR: [<ffff00000808e9bc>] handle_IPI+0x174/0x1d8 +coresight-cpu-debug 850000.debug: EDCIDSR: 00000000 +coresight-cpu-debug 850000.debug: EDVIDSR: 90000000 (State:Non-secure Mode:EL1/0 Width:64bits VMID:0) +coresight-cpu-debug 852000.debug: CPU[1]: +coresight-cpu-debug 852000.debug: EDPRSR: 00000001 (Power:On DLK:Unlock) +coresight-cpu-debug 852000.debug: EDPCSR: [<ffff0000087fab34>] debug_notifier_call+0x23c/0x358 +coresight-cpu-debug 852000.debug: EDCIDSR: 00000000 +coresight-cpu-debug 852000.debug: EDVIDSR: 90000000 (State:Non-secure Mode:EL1/0 Width:64bits VMID:0) diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt index 94a987bd2bc5..fff8ff6d4893 100644 --- a/Documentation/trace/ftrace.txt +++ b/Documentation/trace/ftrace.txt @@ -1609,7 +1609,7 @@ Doing the same with chrt -r 5 and function-trace set. <idle>-0 3dN.2 14us : sched_avg_update <-__cpu_load_update <idle>-0 3dN.2 14us : _raw_spin_unlock <-cpu_load_update_nohz <idle>-0 3dN.2 14us : sub_preempt_count <-_raw_spin_unlock - <idle>-0 3dN.1 15us : calc_load_exit_idle <-tick_nohz_idle_exit + <idle>-0 3dN.1 15us : calc_load_nohz_stop <-tick_nohz_idle_exit <idle>-0 3dN.1 15us : touch_softlockup_watchdog <-tick_nohz_idle_exit <idle>-0 3dN.1 15us : hrtimer_cancel <-tick_nohz_idle_exit <idle>-0 3dN.1 15us : hrtimer_try_to_cancel <-hrtimer_cancel diff --git a/Documentation/translations/ja_JP/howto.rst b/Documentation/translations/ja_JP/howto.rst index 4511eed0fabb..8d7ed0cbbf5f 100644 --- a/Documentation/translations/ja_JP/howto.rst +++ b/Documentation/translations/ja_JP/howto.rst @@ -197,13 +197,6 @@ ReSTマークアップを使ったドキュメントは Documentation/outputに make latexdocs make epubdocs -現在、幾つかの DocBook形式で書かれたドキュメントは ReST形式に転換中で -す。それらのドキュメントはDocumentation/DocBook ディレクトリに生成され、 -Postscript または man ページの形式を生成するには以下のようにします - :: - - make psdocs - make mandocs - カーネル開発者になるには ------------------------ diff --git a/Documentation/translations/ko_KR/howto.rst b/Documentation/translations/ko_KR/howto.rst index 2333697251dd..624654bdcd8a 100644 --- a/Documentation/translations/ko_KR/howto.rst +++ b/Documentation/translations/ko_KR/howto.rst @@ -191,13 +191,6 @@ ReST 마크업을 사용하는 문서들은 Documentation/output 에 생성된 make latexdocs make epubdocs -현재, ReST 로의 변환이 진행중인, DocBook 으로 쓰인 문서들이 존재한다. 그런 -문서들은 Documentation/DocBook/ 디렉토리 안에 생성될 것이고 다음 커맨드를 통해 -Postscript 나 man page 로도 만들어질 수 있다:: - - make psdocs - make mandocs - 커널 개발자가 되는 것 --------------------- @@ -270,15 +263,17 @@ pub/linux/kernel/v4.x/ 디렉토리에서 참조될 수 있다.개발 프로세 선호되는 방법은 git(커널의 소스 관리 툴, 더 많은 정보들은 https://git-scm.com/ 에서 참조할 수 있다)를 사용하는 것이지만 순수한 패치파일의 형식으로 보내는 것도 무관하다. - - 2주 후에 -rc1 커널이 배포되며 지금부터는 전체 커널의 안정성에 영향을 - 미칠수 있는 새로운 기능들을 포함하지 않는 패치들만이 추가될 수 있다. - 완전히 새로운 드라이버(혹은 파일시스템)는 -rc1 이후에만 받아들여진다는 - 것을 기억해라. 왜냐하면 변경이 자체내에서만 발생하고 추가된 코드가 - 드라이버 외부의 다른 부분에는 영향을 주지 않으므로 그런 변경은 + - 2주 후에 -rc1 커널이 릴리즈되며 여기서부터의 주안점은 새로운 커널을 + 가능한한 안정되게 하는 것이다. 이 시점에서의 대부분의 패치들은 회귀(역자주: 이전에는 존재하지 않았지만 새로운 기능추가나 변경으로 인해 - 생겨난 버그)를 일으킬 만한 위험을 가지고 있지 않기 때문이다. -rc1이 - 배포된 이후에 git를 사용하여 패치들을 Linus에게 보낼수 있지만 패치들은 - 공식적인 메일링 리스트로 보내서 검토를 받을 필요가 있다. + 생겨난 버그)를 고쳐야 한다. 이전부터 존재한 버그는 회귀가 아니므로, 그런 + 버그에 대한 수정사항은 중요한 경우에만 보내져야 한다. 완전히 새로운 + 드라이버(혹은 파일시스템)는 -rc1 이후에만 받아들여진다는 것을 기억해라. + 왜냐하면 변경이 자체내에서만 발생하고 추가된 코드가 드라이버 외부의 다른 + 부분에는 영향을 주지 않으므로 그런 변경은 회귀를 일으킬 만한 위험을 가지고 + 있지 않기 때문이다. -rc1이 배포된 이후에 git를 사용하여 패치들을 Linus에게 + 보낼수 있지만 패치들은 공식적인 메일링 리스트로 보내서 검토를 받을 필요가 + 있다. - 새로운 -rc는 Linus가 현재 git tree가 테스트 하기에 충분히 안정된 상태에 있다고 판단될 때마다 배포된다. 목표는 새로운 -rc 커널을 매주 배포하는 것이다. @@ -359,7 +354,7 @@ http://patchwork.ozlabs.org/ 에 나열되어 있다. 버그 보고 --------- -https://bugzilla.kernel.org는 리눅스 커널 개발자들이 커널의 버그를 추적하는 +https://bugzilla.kernel.org 는 리눅스 커널 개발자들이 커널의 버그를 추적하는 곳이다. 사용자들은 발견한 모든 버그들을 보고하기 위하여 이 툴을 사용할 것을 권장한다. kernel bugzilla를 사용하는 자세한 방법은 다음을 참조하라. diff --git a/Documentation/translations/ko_KR/memory-barriers.txt b/Documentation/translations/ko_KR/memory-barriers.txt index d05d4c54e8f7..c6f4ead76ce7 100644 --- a/Documentation/translations/ko_KR/memory-barriers.txt +++ b/Documentation/translations/ko_KR/memory-barriers.txt @@ -786,7 +786,7 @@ CPU 는 b 로부터의 로드 오퍼레이션이 a 로부터의 로드 오퍼레 위의 코드를 아래와 같이 바꿔버릴 수 있습니다: q = READ_ONCE(a); - WRITE_ONCE(b, 1); + WRITE_ONCE(b, 2); do_something_else(); 이렇게 되면, CPU 는 변수 'a' 로부터의 로드와 변수 'b' 로의 스토어 사이의 순서를 diff --git a/Documentation/usb/gadget-testing.txt b/Documentation/usb/gadget-testing.txt index fb0cc4df1765..fbc397d17e98 100644 --- a/Documentation/usb/gadget-testing.txt +++ b/Documentation/usb/gadget-testing.txt @@ -16,10 +16,11 @@ provided by gadgets. 13. RNDIS function 14. SERIAL function 15. SOURCESINK function -16. UAC1 function +16. UAC1 function (legacy implementation) 17. UAC2 function 18. UVC function 19. PRINTER function +20. UAC1 function (new API) 1. ACM function @@ -589,15 +590,16 @@ device: run the gadget host: test-usb (tools/usb/testusb.c) -16. UAC1 function +16. UAC1 function (legacy implementation) ================= -The function is provided by usb_f_uac1.ko module. +The function is provided by usb_f_uac1_legacy.ko module. Function-specific configfs interface ------------------------------------ -The function name to use when creating the function directory is "uac1". +The function name to use when creating the function directory +is "uac1_legacy". The uac1 function provides these attributes in its function directory: audio_buf_size - audio buffer size @@ -772,3 +774,46 @@ host: More advanced testing can be done with the prn_example described in Documentation/usb/gadget-printer.txt. + + +20. UAC1 function (virtual ALSA card, using u_audio API) +================= + +The function is provided by usb_f_uac1.ko module. +It will create a virtual ALSA card and the audio streams are simply +sinked to and sourced from it. + +Function-specific configfs interface +------------------------------------ + +The function name to use when creating the function directory is "uac1". +The uac1 function provides these attributes in its function directory: + + c_chmask - capture channel mask + c_srate - capture sampling rate + c_ssize - capture sample size (bytes) + p_chmask - playback channel mask + p_srate - playback sampling rate + p_ssize - playback sample size (bytes) + req_number - the number of pre-allocated request for both capture + and playback + +The attributes have sane default values. + +Testing the UAC1 function +------------------------- + +device: run the gadget +host: aplay -l # should list our USB Audio Gadget + +This function does not require real hardware support, it just +sends a stream of audio data to/from the host. In order to +actually hear something at the device side, a command similar +to this must be used at the device side: + +$ arecord -f dat -t wav -D hw:2,0 | aplay -D hw:0,0 & + +e.g.: + +$ arecord -f dat -t wav -D hw:CARD=UAC1Gadget,DEV=0 | \ +aplay -D default:CARD=OdroidU3 diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst index a9d01b44a659..7b2eb1b7d4ca 100644 --- a/Documentation/userspace-api/index.rst +++ b/Documentation/userspace-api/index.rst @@ -16,6 +16,8 @@ place where this information is gathered. .. toctree:: :maxdepth: 2 + no_new_privs + seccomp_filter unshare .. only:: subproject and html diff --git a/Documentation/prctl/no_new_privs.txt b/Documentation/userspace-api/no_new_privs.rst index f7be84fba910..d060ea217ea1 100644 --- a/Documentation/prctl/no_new_privs.txt +++ b/Documentation/userspace-api/no_new_privs.rst @@ -1,3 +1,7 @@ +====================== +No New Privileges Flag +====================== + The execve system call can grant a newly-started program privileges that its parent did not have. The most obvious examples are setuid/setgid programs and file capabilities. To prevent the parent program from @@ -5,53 +9,55 @@ gaining these privileges as well, the kernel and user code must be careful to prevent the parent from doing anything that could subvert the child. For example: - - The dynamic loader handles LD_* environment variables differently if + - The dynamic loader handles ``LD_*`` environment variables differently if a program is setuid. - chroot is disallowed to unprivileged processes, since it would allow - /etc/passwd to be replaced from the point of view of a process that + ``/etc/passwd`` to be replaced from the point of view of a process that inherited chroot. - The exec code has special handling for ptrace. -These are all ad-hoc fixes. The no_new_privs bit (since Linux 3.5) is a +These are all ad-hoc fixes. The ``no_new_privs`` bit (since Linux 3.5) is a new, generic mechanism to make it safe for a process to modify its execution environment in a manner that persists across execve. Any task -can set no_new_privs. Once the bit is set, it is inherited across fork, -clone, and execve and cannot be unset. With no_new_privs set, execve +can set ``no_new_privs``. Once the bit is set, it is inherited across fork, +clone, and execve and cannot be unset. With ``no_new_privs`` set, ``execve()`` promises not to grant the privilege to do anything that could not have been done without the execve call. For example, the setuid and setgid bits will no longer change the uid or gid; file capabilities will not add to the permitted set, and LSMs will not relax constraints after execve. -To set no_new_privs, use prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0). +To set ``no_new_privs``, use:: + + prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0); Be careful, though: LSMs might also not tighten constraints on exec -in no_new_privs mode. (This means that setting up a general-purpose -service launcher to set no_new_privs before execing daemons may +in ``no_new_privs`` mode. (This means that setting up a general-purpose +service launcher to set ``no_new_privs`` before execing daemons may interfere with LSM-based sandboxing.) -Note that no_new_privs does not prevent privilege changes that do not -involve execve. An appropriately privileged task can still call -setuid(2) and receive SCM_RIGHTS datagrams. +Note that ``no_new_privs`` does not prevent privilege changes that do not +involve ``execve()``. An appropriately privileged task can still call +``setuid(2)`` and receive SCM_RIGHTS datagrams. -There are two main use cases for no_new_privs so far: +There are two main use cases for ``no_new_privs`` so far: - Filters installed for the seccomp mode 2 sandbox persist across execve and can change the behavior of newly-executed programs. Unprivileged users are therefore only allowed to install such filters - if no_new_privs is set. + if ``no_new_privs`` is set. - - By itself, no_new_privs can be used to reduce the attack surface + - By itself, ``no_new_privs`` can be used to reduce the attack surface available to an unprivileged user. If everything running with a - given uid has no_new_privs set, then that uid will be unable to + given uid has ``no_new_privs`` set, then that uid will be unable to escalate its privileges by directly attacking setuid, setgid, and fcap-using binaries; it will need to compromise something without the - no_new_privs bit set first. + ``no_new_privs`` bit set first. In the future, other potentially dangerous kernel features could become -available to unprivileged tasks if no_new_privs is set. In principle, -several options to unshare(2) and clone(2) would be safe when -no_new_privs is set, and no_new_privs + chroot is considerable less +available to unprivileged tasks if ``no_new_privs`` is set. In principle, +several options to ``unshare(2)`` and ``clone(2)`` would be safe when +``no_new_privs`` is set, and ``no_new_privs`` + ``chroot`` is considerable less dangerous than chroot by itself. diff --git a/Documentation/prctl/seccomp_filter.txt b/Documentation/userspace-api/seccomp_filter.rst index 1e469ef75778..f71eb5ef1f2d 100644 --- a/Documentation/prctl/seccomp_filter.txt +++ b/Documentation/userspace-api/seccomp_filter.rst @@ -1,8 +1,9 @@ - SECure COMPuting with filters - ============================= +=========================================== +Seccomp BPF (SECure COMPuting with filters) +=========================================== Introduction ------------- +============ A large number of system calls are exposed to every userland process with many of them going unused for the entire lifetime of the process. @@ -27,7 +28,7 @@ pointers which constrains all filters to solely evaluating the system call arguments directly. What it isn't -------------- +============= System call filtering isn't a sandbox. It provides a clearly defined mechanism for minimizing the exposed kernel surface. It is meant to be @@ -40,13 +41,13 @@ system calls in socketcall() is allowed, for instance) which could be construed, incorrectly, as a more complete sandboxing solution. Usage ------ +===== An additional seccomp mode is added and is enabled using the same prctl(2) call as the strict seccomp. If the architecture has -CONFIG_HAVE_ARCH_SECCOMP_FILTER, then filters may be added as below: +``CONFIG_HAVE_ARCH_SECCOMP_FILTER``, then filters may be added as below: -PR_SET_SECCOMP: +``PR_SET_SECCOMP``: Now takes an additional argument which specifies a new filter using a BPF program. The BPF program will be executed over struct seccomp_data @@ -55,24 +56,25 @@ PR_SET_SECCOMP: acceptable values to inform the kernel which action should be taken. - Usage: + Usage:: + prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, prog); The 'prog' argument is a pointer to a struct sock_fprog which will contain the filter program. If the program is invalid, the - call will return -1 and set errno to EINVAL. + call will return -1 and set errno to ``EINVAL``. - If fork/clone and execve are allowed by @prog, any child + If ``fork``/``clone`` and ``execve`` are allowed by @prog, any child processes will be constrained to the same filters and system call ABI as the parent. - Prior to use, the task must call prctl(PR_SET_NO_NEW_PRIVS, 1) or - run with CAP_SYS_ADMIN privileges in its namespace. If these are not - true, -EACCES will be returned. This requirement ensures that filter + Prior to use, the task must call ``prctl(PR_SET_NO_NEW_PRIVS, 1)`` or + run with ``CAP_SYS_ADMIN`` privileges in its namespace. If these are not + true, ``-EACCES`` will be returned. This requirement ensures that filter programs cannot be applied to child processes with greater privileges than the task that installed them. - Additionally, if prctl(2) is allowed by the attached filter, + Additionally, if ``prctl(2)`` is allowed by the attached filter, additional filters may be layered on which will increase evaluation time, but allow for further decreasing the attack surface during execution of a process. @@ -80,51 +82,52 @@ PR_SET_SECCOMP: The above call returns 0 on success and non-zero on error. Return values -------------- +============= + A seccomp filter may return any of the following values. If multiple filters exist, the return value for the evaluation of a given system call will always use the highest precedent value. (For example, -SECCOMP_RET_KILL will always take precedence.) +``SECCOMP_RET_KILL`` will always take precedence.) In precedence order, they are: -SECCOMP_RET_KILL: +``SECCOMP_RET_KILL``: Results in the task exiting immediately without executing the - system call. The exit status of the task (status & 0x7f) will - be SIGSYS, not SIGKILL. + system call. The exit status of the task (``status & 0x7f``) will + be ``SIGSYS``, not ``SIGKILL``. -SECCOMP_RET_TRAP: - Results in the kernel sending a SIGSYS signal to the triggering - task without executing the system call. siginfo->si_call_addr +``SECCOMP_RET_TRAP``: + Results in the kernel sending a ``SIGSYS`` signal to the triggering + task without executing the system call. ``siginfo->si_call_addr`` will show the address of the system call instruction, and - siginfo->si_syscall and siginfo->si_arch will indicate which + ``siginfo->si_syscall`` and ``siginfo->si_arch`` will indicate which syscall was attempted. The program counter will be as though the syscall happened (i.e. it will not point to the syscall instruction). The return value register will contain an arch- dependent value -- if resuming execution, set it to something sensible. (The architecture dependency is because replacing - it with -ENOSYS could overwrite some useful information.) + it with ``-ENOSYS`` could overwrite some useful information.) - The SECCOMP_RET_DATA portion of the return value will be passed - as si_errno. + The ``SECCOMP_RET_DATA`` portion of the return value will be passed + as ``si_errno``. - SIGSYS triggered by seccomp will have a si_code of SYS_SECCOMP. + ``SIGSYS`` triggered by seccomp will have a si_code of ``SYS_SECCOMP``. -SECCOMP_RET_ERRNO: +``SECCOMP_RET_ERRNO``: Results in the lower 16-bits of the return value being passed to userland as the errno without executing the system call. -SECCOMP_RET_TRACE: +``SECCOMP_RET_TRACE``: When returned, this value will cause the kernel to attempt to - notify a ptrace()-based tracer prior to executing the system - call. If there is no tracer present, -ENOSYS is returned to + notify a ``ptrace()``-based tracer prior to executing the system + call. If there is no tracer present, ``-ENOSYS`` is returned to userland and the system call is not executed. - A tracer will be notified if it requests PTRACE_O_TRACESECCOMP - using ptrace(PTRACE_SETOPTIONS). The tracer will be notified - of a PTRACE_EVENT_SECCOMP and the SECCOMP_RET_DATA portion of + A tracer will be notified if it requests ``PTRACE_O_TRACESECCOM``P + using ``ptrace(PTRACE_SETOPTIONS)``. The tracer will be notified + of a ``PTRACE_EVENT_SECCOMP`` and the ``SECCOMP_RET_DATA`` portion of the BPF program return value will be available to the tracer - via PTRACE_GETEVENTMSG. + via ``PTRACE_GETEVENTMSG``. The tracer can skip the system call by changing the syscall number to -1. Alternatively, the tracer can change the system call @@ -138,19 +141,19 @@ SECCOMP_RET_TRACE: allow use of ptrace, even of other sandboxed processes, without extreme care; ptracers can use this mechanism to escape.) -SECCOMP_RET_ALLOW: +``SECCOMP_RET_ALLOW``: Results in the system call being executed. If multiple filters exist, the return value for the evaluation of a given system call will always use the highest precedent value. -Precedence is only determined using the SECCOMP_RET_ACTION mask. When +Precedence is only determined using the ``SECCOMP_RET_ACTION`` mask. When multiple filters return values of the same precedence, only the -SECCOMP_RET_DATA from the most recently installed filter will be +``SECCOMP_RET_DATA`` from the most recently installed filter will be returned. Pitfalls --------- +======== The biggest pitfall to avoid during use is filtering on system call number without checking the architecture value. Why? On any @@ -160,39 +163,40 @@ the numbers in the different calling conventions overlap, then checks in the filters may be abused. Always check the arch value! Example -------- +======= -The samples/seccomp/ directory contains both an x86-specific example +The ``samples/seccomp/`` directory contains both an x86-specific example and a more generic example of a higher level macro interface for BPF program generation. Adding architecture support ------------------------ +=========================== -See arch/Kconfig for the authoritative requirements. In general, if an +See ``arch/Kconfig`` for the authoritative requirements. In general, if an architecture supports both ptrace_event and seccomp, it will be able to -support seccomp filter with minor fixup: SIGSYS support and seccomp return -value checking. Then it must just add CONFIG_HAVE_ARCH_SECCOMP_FILTER +support seccomp filter with minor fixup: ``SIGSYS`` support and seccomp return +value checking. Then it must just add ``CONFIG_HAVE_ARCH_SECCOMP_FILTER`` to its arch-specific Kconfig. Caveats -------- +======= The vDSO can cause some system calls to run entirely in userspace, leading to surprises when you run programs on different machines that fall back to real syscalls. To minimize these surprises on x86, make sure you test with -/sys/devices/system/clocksource/clocksource0/current_clocksource set to -something like acpi_pm. +``/sys/devices/system/clocksource/clocksource0/current_clocksource`` set to +something like ``acpi_pm``. On x86-64, vsyscall emulation is enabled by default. (vsyscalls are -legacy variants on vDSO calls.) Currently, emulated vsyscalls will honor seccomp, with a few oddities: +legacy variants on vDSO calls.) Currently, emulated vsyscalls will +honor seccomp, with a few oddities: -- A return value of SECCOMP_RET_TRAP will set a si_call_addr pointing to +- A return value of ``SECCOMP_RET_TRAP`` will set a ``si_call_addr`` pointing to the vsyscall entry for the given call and not the address after the 'syscall' instruction. Any code which wants to restart the call should be aware that (a) a ret instruction has been emulated and (b) @@ -200,7 +204,7 @@ legacy variants on vDSO calls.) Currently, emulated vsyscalls will honor seccom emulation security checks, making resuming the syscall mostly pointless. -- A return value of SECCOMP_RET_TRACE will signal the tracer as usual, +- A return value of ``SECCOMP_RET_TRACE`` will signal the tracer as usual, but the syscall may not be changed to another system call using the orig_rax register. It may only be changed to -1 order to skip the currently emulated call. Any other change MAY terminate the process. @@ -209,14 +213,14 @@ legacy variants on vDSO calls.) Currently, emulated vsyscalls will honor seccom rip or rsp. (Do not rely on other changes terminating the process. They might work. For example, on some kernels, choosing a syscall that only exists in future kernels will be correctly emulated (by - returning -ENOSYS). + returning ``-ENOSYS``). -To detect this quirky behavior, check for addr & ~0x0C00 == -0xFFFFFFFFFF600000. (For SECCOMP_RET_TRACE, use rip. For -SECCOMP_RET_TRAP, use siginfo->si_call_addr.) Do not check any other +To detect this quirky behavior, check for ``addr & ~0x0C00 == +0xFFFFFFFFFF600000``. (For ``SECCOMP_RET_TRACE``, use rip. For +``SECCOMP_RET_TRAP``, use ``siginfo->si_call_addr``.) Do not check any other condition: future kernels may improve vsyscall emulation and current kernels in vsyscall=native mode will behave differently, but the -instructions at 0xF...F600{0,4,8,C}00 will not be system calls in these +instructions at ``0xF...F600{0,4,8,C}00`` will not be system calls in these cases. Note that modern systems are unlikely to use vsyscalls at all -- they diff --git a/Documentation/userspace-api/unshare.rst b/Documentation/userspace-api/unshare.rst index 737c192cf4e7..877e90a35238 100644 --- a/Documentation/userspace-api/unshare.rst +++ b/Documentation/userspace-api/unshare.rst @@ -107,7 +107,7 @@ the benefits of this new feature can exceed its cost. unshare() reverses sharing that was done using clone(2) system call, so unshare() should have a similar interface as clone(2). That is, -since flags in clone(int flags, void *stack) specifies what should +since flags in clone(int flags, void \*stack) specifies what should be shared, similar flags in unshare(int flags) should specify what should be unshared. Unfortunately, this may appear to invert the meaning of the flags from the way they are used in clone(2). diff --git a/Documentation/watchdog/watchdog-parameters.txt b/Documentation/watchdog/watchdog-parameters.txt index 4f7d86dd0a5d..914518aeb972 100644 --- a/Documentation/watchdog/watchdog-parameters.txt +++ b/Documentation/watchdog/watchdog-parameters.txt @@ -117,7 +117,7 @@ nowayout: Watchdog cannot be stopped once started ------------------------------------------------- iTCO_wdt: heartbeat: Watchdog heartbeat in seconds. - (2<heartbeat<39 (TCO v1) or 613 (TCO v2), default=30) + (5<=heartbeat<=74 (TCO v1) or 1226 (TCO v2), default=30) nowayout: Watchdog cannot be stopped once started (default=kernel config parameter) ------------------------------------------------- diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt index 61b611e9eeaf..b297c48389b9 100644 --- a/Documentation/x86/x86_64/boot-options.txt +++ b/Documentation/x86/x86_64/boot-options.txt @@ -36,7 +36,8 @@ Machine check to broadcast MCEs. mce=bootlog Enable logging of machine checks left over from booting. - Disabled by default on AMD because some BIOS leave bogus ones. + Disabled by default on AMD Fam10h and older because some BIOS + leave bogus ones. If your BIOS doesn't do that it's a good idea to enable though to make sure you log even machine check events that result in a reboot. On Intel systems it is enabled by default. |