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Diffstat (limited to 'drivers/staging/android/uapi')
-rw-r--r-- | drivers/staging/android/uapi/vsoc_shm.h | 295 |
1 files changed, 0 insertions, 295 deletions
diff --git a/drivers/staging/android/uapi/vsoc_shm.h b/drivers/staging/android/uapi/vsoc_shm.h deleted file mode 100644 index 6291fb24efb2..000000000000 --- a/drivers/staging/android/uapi/vsoc_shm.h +++ /dev/null @@ -1,295 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -/* - * Copyright (C) 2017 Google, Inc. - * - */ - -#ifndef _UAPI_LINUX_VSOC_SHM_H -#define _UAPI_LINUX_VSOC_SHM_H - -#include <linux/types.h> - -/** - * A permission is a token that permits a receiver to read and/or write an area - * of memory within a Vsoc region. - * - * An fd_scoped permission grants both read and write access, and can be - * attached to a file description (see open(2)). - * Ownership of the area can then be shared by passing a file descriptor - * among processes. - * - * begin_offset and end_offset define the area of memory that is controlled by - * the permission. owner_offset points to a word, also in shared memory, that - * controls ownership of the area. - * - * ownership of the region expires when the associated file description is - * released. - * - * At most one permission can be attached to each file description. - * - * This is useful when implementing HALs like gralloc that scope and pass - * ownership of shared resources via file descriptors. - * - * The caller is responsibe for doing any fencing. - * - * The calling process will normally identify a currently free area of - * memory. It will construct a proposed fd_scoped_permission_arg structure: - * - * begin_offset and end_offset describe the area being claimed - * - * owner_offset points to the location in shared memory that indicates the - * owner of the area. - * - * owned_value is the value that will be stored in owner_offset iff the - * permission can be granted. It must be different than VSOC_REGION_FREE. - * - * Two fd_scoped_permission structures are compatible if they vary only by - * their owned_value fields. - * - * The driver ensures that, for any group of simultaneous callers proposing - * compatible fd_scoped_permissions, it will accept exactly one of the - * propopsals. The other callers will get a failure with errno of EAGAIN. - * - * A process receiving a file descriptor can identify the region being - * granted using the VSOC_GET_FD_SCOPED_PERMISSION ioctl. - */ -struct fd_scoped_permission { - __u32 begin_offset; - __u32 end_offset; - __u32 owner_offset; - __u32 owned_value; -}; - -/* - * This value represents a free area of memory. The driver expects to see this - * value at owner_offset when creating a permission otherwise it will not do it, - * and will write this value back once the permission is no longer needed. - */ -#define VSOC_REGION_FREE ((__u32)0) - -/** - * ioctl argument for VSOC_CREATE_FD_SCOPE_PERMISSION - */ -struct fd_scoped_permission_arg { - struct fd_scoped_permission perm; - __s32 managed_region_fd; -}; - -#define VSOC_NODE_FREE ((__u32)0) - -/* - * Describes a signal table in shared memory. Each non-zero entry in the - * table indicates that the receiver should signal the futex at the given - * offset. Offsets are relative to the region, not the shared memory window. - * - * interrupt_signalled_offset is used to reliably signal interrupts across the - * vmm boundary. There are two roles: transmitter and receiver. For example, - * in the host_to_guest_signal_table the host is the transmitter and the - * guest is the receiver. The protocol is as follows: - * - * 1. The transmitter should convert the offset of the futex to an offset - * in the signal table [0, (1 << num_nodes_lg2)) - * The transmitter can choose any appropriate hashing algorithm, including - * hash = futex_offset & ((1 << num_nodes_lg2) - 1) - * - * 3. The transmitter should atomically compare and swap futex_offset with 0 - * at hash. There are 3 possible outcomes - * a. The swap fails because the futex_offset is already in the table. - * The transmitter should stop. - * b. Some other offset is in the table. This is a hash collision. The - * transmitter should move to another table slot and try again. One - * possible algorithm: - * hash = (hash + 1) & ((1 << num_nodes_lg2) - 1) - * c. The swap worked. Continue below. - * - * 3. The transmitter atomically swaps 1 with the value at the - * interrupt_signalled_offset. There are two outcomes: - * a. The prior value was 1. In this case an interrupt has already been - * posted. The transmitter is done. - * b. The prior value was 0, indicating that the receiver may be sleeping. - * The transmitter will issue an interrupt. - * - * 4. On waking the receiver immediately exchanges a 0 with the - * interrupt_signalled_offset. If it receives a 0 then this a spurious - * interrupt. That may occasionally happen in the current protocol, but - * should be rare. - * - * 5. The receiver scans the signal table by atomicaly exchanging 0 at each - * location. If a non-zero offset is returned from the exchange the - * receiver wakes all sleepers at the given offset: - * futex((int*)(region_base + old_value), FUTEX_WAKE, MAX_INT); - * - * 6. The receiver thread then does a conditional wait, waking immediately - * if the value at interrupt_signalled_offset is non-zero. This catches cases - * here additional signals were posted while the table was being scanned. - * On the guest the wait is handled via the VSOC_WAIT_FOR_INCOMING_INTERRUPT - * ioctl. - */ -struct vsoc_signal_table_layout { - /* log_2(Number of signal table entries) */ - __u32 num_nodes_lg2; - /* - * Offset to the first signal table entry relative to the start of the - * region - */ - __u32 futex_uaddr_table_offset; - /* - * Offset to an atomic_t / atomic uint32_t. A non-zero value indicates - * that one or more offsets are currently posted in the table. - * semi-unique access to an entry in the table - */ - __u32 interrupt_signalled_offset; -}; - -#define VSOC_REGION_WHOLE ((__s32)0) -#define VSOC_DEVICE_NAME_SZ 16 - -/** - * Each HAL would (usually) talk to a single device region - * Mulitple entities care about these regions: - * - The ivshmem_server will populate the regions in shared memory - * - The guest kernel will read the region, create minor device nodes, and - * allow interested parties to register for FUTEX_WAKE events in the region - * - HALs will access via the minor device nodes published by the guest kernel - * - Host side processes will access the region via the ivshmem_server: - * 1. Pass name to ivshmem_server at a UNIX socket - * 2. ivshmemserver will reply with 2 fds: - * - host->guest doorbell fd - * - guest->host doorbell fd - * - fd for the shared memory region - * - region offset - * 3. Start a futex receiver thread on the doorbell fd pointed at the - * signal_nodes - */ -struct vsoc_device_region { - __u16 current_version; - __u16 min_compatible_version; - __u32 region_begin_offset; - __u32 region_end_offset; - __u32 offset_of_region_data; - struct vsoc_signal_table_layout guest_to_host_signal_table; - struct vsoc_signal_table_layout host_to_guest_signal_table; - /* Name of the device. Must always be terminated with a '\0', so - * the longest supported device name is 15 characters. - */ - char device_name[VSOC_DEVICE_NAME_SZ]; - /* There are two ways that permissions to access regions are handled: - * - When subdivided_by is VSOC_REGION_WHOLE, any process that can - * open the device node for the region gains complete access to it. - * - When subdivided is set processes that open the region cannot - * access it. Access to a sub-region must be established by invoking - * the VSOC_CREATE_FD_SCOPE_PERMISSION ioctl on the region - * referenced in subdivided_by, providing a fileinstance - * (represented by a fd) opened on this region. - */ - __u32 managed_by; -}; - -/* - * The vsoc layout descriptor. - * The first 4K should be reserved for the shm header and region descriptors. - * The regions should be page aligned. - */ - -struct vsoc_shm_layout_descriptor { - __u16 major_version; - __u16 minor_version; - - /* size of the shm. This may be redundant but nice to have */ - __u32 size; - - /* number of shared memory regions */ - __u32 region_count; - - /* The offset to the start of region descriptors */ - __u32 vsoc_region_desc_offset; -}; - -/* - * This specifies the current version that should be stored in - * vsoc_shm_layout_descriptor.major_version and - * vsoc_shm_layout_descriptor.minor_version. - * It should be updated only if the vsoc_device_region and - * vsoc_shm_layout_descriptor structures have changed. - * Versioning within each region is transferred - * via the min_compatible_version and current_version fields in - * vsoc_device_region. The driver does not consult these fields: they are left - * for the HALs and host processes and will change independently of the layout - * version. - */ -#define CURRENT_VSOC_LAYOUT_MAJOR_VERSION 2 -#define CURRENT_VSOC_LAYOUT_MINOR_VERSION 0 - -#define VSOC_CREATE_FD_SCOPED_PERMISSION \ - _IOW(0xF5, 0, struct fd_scoped_permission) -#define VSOC_GET_FD_SCOPED_PERMISSION _IOR(0xF5, 1, struct fd_scoped_permission) - -/* - * This is used to signal the host to scan the guest_to_host_signal_table - * for new futexes to wake. This sends an interrupt if one is not already - * in flight. - */ -#define VSOC_MAYBE_SEND_INTERRUPT_TO_HOST _IO(0xF5, 2) - -/* - * When this returns the guest will scan host_to_guest_signal_table to - * check for new futexes to wake. - */ -/* TODO(ghartman): Consider moving this to the bottom half */ -#define VSOC_WAIT_FOR_INCOMING_INTERRUPT _IO(0xF5, 3) - -/* - * Guest HALs will use this to retrieve the region description after - * opening their device node. - */ -#define VSOC_DESCRIBE_REGION _IOR(0xF5, 4, struct vsoc_device_region) - -/* - * Wake any threads that may be waiting for a host interrupt on this region. - * This is mostly used during shutdown. - */ -#define VSOC_SELF_INTERRUPT _IO(0xF5, 5) - -/* - * This is used to signal the host to scan the guest_to_host_signal_table - * for new futexes to wake. This sends an interrupt unconditionally. - */ -#define VSOC_SEND_INTERRUPT_TO_HOST _IO(0xF5, 6) - -enum wait_types { - VSOC_WAIT_UNDEFINED = 0, - VSOC_WAIT_IF_EQUAL = 1, - VSOC_WAIT_IF_EQUAL_TIMEOUT = 2 -}; - -/* - * Wait for a condition to be true - * - * Note, this is sized and aligned so the 32 bit and 64 bit layouts are - * identical. - */ -struct vsoc_cond_wait { - /* Input: Offset of the 32 bit word to check */ - __u32 offset; - /* Input: Value that will be compared with the offset */ - __u32 value; - /* Monotonic time to wake at in seconds */ - __u64 wake_time_sec; - /* Input: Monotonic time to wait in nanoseconds */ - __u32 wake_time_nsec; - /* Input: Type of wait */ - __u32 wait_type; - /* Output: Number of times the thread woke before returning. */ - __u32 wakes; - /* Ensure that we're 8-byte aligned and 8 byte length for 32/64 bit - * compatibility. - */ - __u32 reserved_1; -}; - -#define VSOC_COND_WAIT _IOWR(0xF5, 7, struct vsoc_cond_wait) - -/* Wake any local threads waiting at the offset given in arg */ -#define VSOC_COND_WAKE _IO(0xF5, 8) - -#endif /* _UAPI_LINUX_VSOC_SHM_H */ |