<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-dev/arch/arm/include, branch linus/master</title>
<subtitle>Linux kernel development work - see feature branches</subtitle>
<id>https://git.zx2c4.com/linux-dev/atom/arch/arm/include?h=linus%2Fmaster</id>
<link rel='self' href='https://git.zx2c4.com/linux-dev/atom/arch/arm/include?h=linus%2Fmaster'/>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/'/>
<updated>2022-06-06T06:54:33Z</updated>
<entry>
<title>arm/xen: Introduce xen_setup_dma_ops()</title>
<updated>2022-06-06T06:54:33Z</updated>
<author>
<name>Oleksandr Tyshchenko</name>
<email>oleksandr_tyshchenko@epam.com</email>
</author>
<published>2022-06-02T19:23:46Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=9bf22421dc8a69cade3c994771637e9693ff0216'/>
<id>urn:sha1:9bf22421dc8a69cade3c994771637e9693ff0216</id>
<content type='text'>
This patch introduces new helper and places it in new header.
The helper's purpose is to assign any Xen specific DMA ops in
a single place. For now, we deal with xen-swiotlb DMA ops only.
The one of the subsequent commits in current series will add
xen-grant DMA ops case.

Also re-use the xen_swiotlb_detect() check on Arm32.

Signed-off-by: Oleksandr Tyshchenko &lt;oleksandr_tyshchenko@epam.com&gt;
Reviewed-by: Stefano Stabellini &lt;sstabellini@kernel.org&gt;
[For arm64]
Acked-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Link: https://lore.kernel.org/r/1654197833-25362-2-git-send-email-olekstysh@gmail.com
Signed-off-by: Juergen Gross &lt;jgross@suse.com&gt;
</content>
</entry>
<entry>
<title>Merge tag 'arm-multiplatform-5.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc</title>
<updated>2022-06-02T22:23:54Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-06-02T22:23:54Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=96479c09803b21d195c95fd4b145cd3a5a591ba0'/>
<id>urn:sha1:96479c09803b21d195c95fd4b145cd3a5a591ba0</id>
<content type='text'>
Pull more ARM multiplatform updates from Arnd Bergmann:
 "The second part of the multiplatform changes now converts the
  Intel/Marvell PXA platform along with the rest. The patches went
  through several rebases before the merge window as bugs were found, so
  they remained separate.

  This has to touch a lot of drivers, in particular the touchscreen,
  pcmcia, sound and clk bits, to detach the driver files from the
  platform and board specific header files"

* tag 'arm-multiplatform-5.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (48 commits)
  ARM: pxa/mmp: remove traces of plat-pxa
  ARM: pxa: convert to multiplatform
  ARM: pxa/sa1100: move I/O space to PCI_IOBASE
  ARM: pxa: remove support for MTD_XIP
  ARM: pxa: move mach/*.h to mach-pxa/
  ARM: PXA: fix multi-cpu build of xsc3
  ARM: pxa: move plat-pxa to drivers/soc/
  ARM: mmp: rename pxa_register_device
  ARM: mmp: remove tavorevb board support
  ARM: pxa: remove unused mach/bitfield.h
  ARM: pxa: move clk register definitions to driver
  ARM: pxa: move smemc register access from clk to platform
  cpufreq: pxa3: move clk register access to clk driver
  ARM: pxa: remove get_clk_frequency_khz()
  ARM: pxa: pcmcia: move smemc configuration back to arch
  ASoC: pxa: i2s: use normal MMIO accessors
  ASoC: pxa: ac97: use normal MMIO accessors
  ASoC: pxa: use pdev resource for FIFO regs
  Input: wm97xx - get rid of irq_enable method in wm97xx_mach_ops
  Input: wm97xx - switch to using threaded IRQ
  ...
</content>
</entry>
<entry>
<title>Merge tag 'dma-mapping-5.19-2022-05-25' of git://git.infradead.org/users/hch/dma-mapping</title>
<updated>2022-05-26T02:18:36Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-05-26T02:18:36Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=3f306ea2e18568f693f7763d1c2178f349ae8f31'/>
<id>urn:sha1:3f306ea2e18568f693f7763d1c2178f349ae8f31</id>
<content type='text'>
Pull dma-mapping updates from Christoph Hellwig:

 - don't over-decrypt memory (Robin Murphy)

 - takes min align mask into account for the swiotlb max mapping size
   (Tianyu Lan)

 - use GFP_ATOMIC in dma-debug (Mikulas Patocka)

 - fix DMA_ATTR_NO_KERNEL_MAPPING on xen/arm (me)

 - don't fail on highmem CMA pages in dma_direct_alloc_pages (me)

 - cleanup swiotlb initialization and share more code with swiotlb-xen
   (me, Stefano Stabellini)

* tag 'dma-mapping-5.19-2022-05-25' of git://git.infradead.org/users/hch/dma-mapping: (23 commits)
  dma-direct: don't over-decrypt memory
  swiotlb: max mapping size takes min align mask into account
  swiotlb: use the right nslabs-derived sizes in swiotlb_init_late
  swiotlb: use the right nslabs value in swiotlb_init_remap
  swiotlb: don't panic when the swiotlb buffer can't be allocated
  dma-debug: change allocation mode from GFP_NOWAIT to GFP_ATIOMIC
  dma-direct: don't fail on highmem CMA pages in dma_direct_alloc_pages
  swiotlb-xen: fix DMA_ATTR_NO_KERNEL_MAPPING on arm
  x86: remove cruft from &lt;asm/dma-mapping.h&gt;
  swiotlb: remove swiotlb_init_with_tbl and swiotlb_init_late_with_tbl
  swiotlb: merge swiotlb-xen initialization into swiotlb
  swiotlb: provide swiotlb_init variants that remap the buffer
  swiotlb: pass a gfp_mask argument to swiotlb_init_late
  swiotlb: add a SWIOTLB_ANY flag to lift the low memory restriction
  swiotlb: make the swiotlb_init interface more useful
  x86: centralize setting SWIOTLB_FORCE when guest memory encryption is enabled
  x86: remove the IOMMU table infrastructure
  MIPS/octeon: use swiotlb_init instead of open coding it
  arm/xen: don't check for xen_initial_domain() in xen_create_contiguous_region
  swiotlb: rename swiotlb_late_init_with_default_size
  ...
</content>
</entry>
<entry>
<title>Merge tag 'random-5.19-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random</title>
<updated>2022-05-24T18:58:10Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-05-24T18:58:10Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=ac2ab99072cce553c78f326ea22d72856f570d88'/>
<id>urn:sha1:ac2ab99072cce553c78f326ea22d72856f570d88</id>
<content type='text'>
Pull random number generator updates from Jason Donenfeld:
 "These updates continue to refine the work began in 5.17 and 5.18 of
  modernizing the RNG's crypto and streamlining and documenting its
  code.

  New for 5.19, the updates aim to improve entropy collection methods
  and make some initial decisions regarding the "premature next" problem
  and our threat model. The cloc utility now reports that random.c is
  931 lines of code and 466 lines of comments, not that basic metrics
  like that mean all that much, but at the very least it tells you that
  this is very much a manageable driver now.

  Here's a summary of the various updates:

   - The random_get_entropy() function now always returns something at
     least minimally useful. This is the primary entropy source in most
     collectors, which in the best case expands to something like RDTSC,
     but prior to this change, in the worst case it would just return 0,
     contributing nothing. For 5.19, additional architectures are wired
     up, and architectures that are entirely missing a cycle counter now
     have a generic fallback path, which uses the highest resolution
     clock available from the timekeeping subsystem.

     Some of those clocks can actually be quite good, despite the CPU
     not having a cycle counter of its own, and going off-core for a
     stamp is generally thought to increase jitter, something positive
     from the perspective of entropy gathering. Done very early on in
     the development cycle, this has been sitting in next getting some
     testing for a while now and has relevant acks from the archs, so it
     should be pretty well tested and fine, but is nonetheless the thing
     I'll be keeping my eye on most closely.

   - Of particular note with the random_get_entropy() improvements is
     MIPS, which, on CPUs that lack the c0 count register, will now
     combine the high-speed but short-cycle c0 random register with the
     lower-speed but long-cycle generic fallback path.

   - With random_get_entropy() now always returning something useful,
     the interrupt handler now collects entropy in a consistent
     construction.

   - Rather than comparing two samples of random_get_entropy() for the
     jitter dance, the algorithm now tests many samples, and uses the
     amount of differing ones to determine whether or not jitter entropy
     is usable and how laborious it must be. The problem with comparing
     only two samples was that if the cycle counter was extremely slow,
     but just so happened to be on the cusp of a change, the slowness
     wouldn't be detected. Taking many samples fixes that to some
     degree.

     This, combined with the other improvements to random_get_entropy(),
     should make future unification of /dev/random and /dev/urandom
     maybe more possible. At the very least, were we to attempt it again
     today (we're not), it wouldn't break any of Guenter's test rigs
     that broke when we tried it with 5.18. So, not today, but perhaps
     down the road, that's something we can revisit.

   - We attempt to reseed the RNG immediately upon waking up from system
     suspend or hibernation, making use of the various timestamps about
     suspend time and such available, as well as the usual inputs such
     as RDRAND when available.

   - Batched randomness now falls back to ordinary randomness before the
     RNG is initialized. This provides more consistent guarantees to the
     types of random numbers being returned by the various accessors.

   - The "pre-init injection" code is now gone for good. I suspect you
     in particular will be happy to read that, as I recall you
     expressing your distaste for it a few months ago. Instead, to avoid
     a "premature first" issue, while still allowing for maximal amount
     of entropy availability during system boot, the first 128 bits of
     estimated entropy are used immediately as it arrives, with the next
     128 bits being buffered. And, as before, after the RNG has been
     fully initialized, it winds up reseeding anyway a few seconds later
     in most cases. This resulted in a pretty big simplification of the
     initialization code and let us remove various ad-hoc mechanisms
     like the ugly crng_pre_init_inject().

   - The RNG no longer pretends to handle the "premature next" security
     model, something that various academics and other RNG designs have
     tried to care about in the past. After an interesting mailing list
     thread, these issues are thought to be a) mainly academic and not
     practical at all, and b) actively harming the real security of the
     RNG by delaying new entropy additions after a potential compromise,
     making a potentially bad situation even worse. As well, in the
     first place, our RNG never even properly handled the premature next
     issue, so removing an incomplete solution to a fake problem was
     particularly nice.

     This allowed for numerous other simplifications in the code, which
     is a lot cleaner as a consequence. If you didn't see it before,
     https://lore.kernel.org/lkml/YmlMGx6+uigkGiZ0@zx2c4.com/ may be a
     thread worth skimming through.

   - While the interrupt handler received a separate code path years ago
     that avoids locks by using per-cpu data structures and a faster
     mixing algorithm, in order to reduce interrupt latency, input and
     disk events that are triggered in hardirq handlers were still
     hitting locks and more expensive algorithms. Those are now
     redirected to use the faster per-cpu data structures.

   - Rather than having the fake-crypto almost-siphash-based random32
     implementation be used right and left, and in many places where
     cryptographically secure randomness is desirable, the batched
     entropy code is now fast enough to replace that.

   - As usual, numerous code quality and documentation cleanups. For
     example, the initialization state machine now uses enum symbolic
     constants instead of just hard coding numbers everywhere.

   - Since the RNG initializes once, and then is always initialized
     thereafter, a pretty heavy amount of code used during that
     initialization is never used again. It is now completely cordoned
     off using static branches and it winds up in the .text.unlikely
     section so that it doesn't reduce cache compactness after the RNG
     is ready.

   - A variety of functions meant for waiting on the RNG to be
     initialized were only used by vsprintf, and in not a particularly
     optimal way. Replacing that usage with a more ordinary setup made
     it possible to remove those functions.

   - A cleanup of how we warn userspace about the use of uninitialized
     /dev/urandom and uninitialized get_random_bytes() usage.
     Interestingly, with the change you merged for 5.18 that attempts to
     use jitter (but does not block if it can't), the majority of users
     should never see those warnings for /dev/urandom at all now, and
     the one for in-kernel usage is mainly a debug thing.

   - The file_operations struct for /dev/[u]random now implements
     .read_iter and .write_iter instead of .read and .write, allowing it
     to also implement .splice_read and .splice_write, which makes
     splice(2) work again after it was broken here (and in many other
     places in the tree) during the set_fs() removal. This was a bit of
     a last minute arrival from Jens that hasn't had as much time to
     bake, so I'll be keeping my eye on this as well, but it seems
     fairly ordinary. Unfortunately, read_iter() is around 3% slower
     than read() in my tests, which I'm not thrilled about. But Jens and
     Al, spurred by this observation, seem to be making progress in
     removing the bottlenecks on the iter paths in the VFS layer in
     general, which should remove the performance gap for all drivers.

   - Assorted other bug fixes, cleanups, and optimizations.

   - A small SipHash cleanup"

* tag 'random-5.19-rc1-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/crng/random: (49 commits)
  random: check for signals after page of pool writes
  random: wire up fops-&gt;splice_{read,write}_iter()
  random: convert to using fops-&gt;write_iter()
  random: convert to using fops-&gt;read_iter()
  random: unify batched entropy implementations
  random: move randomize_page() into mm where it belongs
  random: remove mostly unused async readiness notifier
  random: remove get_random_bytes_arch() and add rng_has_arch_random()
  random: move initialization functions out of hot pages
  random: make consistent use of buf and len
  random: use proper return types on get_random_{int,long}_wait()
  random: remove extern from functions in header
  random: use static branch for crng_ready()
  random: credit architectural init the exact amount
  random: handle latent entropy and command line from random_init()
  random: use proper jiffies comparison macro
  random: remove ratelimiting for in-kernel unseeded randomness
  random: move initialization out of reseeding hot path
  random: avoid initializing twice in credit race
  random: use symbolic constants for crng_init states
  ...
</content>
</entry>
<entry>
<title>Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm</title>
<updated>2022-05-24T04:04:25Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-05-24T04:04:25Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=d6edf95109661e5fb9b20613478470d2e8fa4455'/>
<id>urn:sha1:d6edf95109661e5fb9b20613478470d2e8fa4455</id>
<content type='text'>
Pull ARM updates from Russell King:

 - amba bus updates

 - simplify ldr_this_cpu assembler macro for uniprocessor builds

 - avoid explicit assembler literal loads

 - more spectre-bhb improvements

 - add Cortex-A9 Errata 764319 workaround

 - add all unwind tables for modules

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 9204/2: module: Add all unwind tables when load module
  ARM: 9206/1: A9: Add ARM ERRATA 764319 workaround (Updated)
  ARM: 9201/1: spectre-bhb: rely on linker to emit cross-section literal loads
  ARM: 9200/1: spectre-bhb: avoid cross-subsection jump using a numbered label
  ARM: 9199/1: spectre-bhb: use local DSB and elide ISB in loop8 sequence
  ARM: 9198/1: spectre-bhb: simplify BPIALL vector macro
  ARM: 9195/1: entry: avoid explicit literal loads
  ARM: 9194/1: assembler: simplify ldr_this_cpu for !SMP builds
  ARM: 9192/1: amba: fix memory leak in amba_device_try_add()
  ARM: 9193/1: amba: Add amba_read_periphid() helper
</content>
</entry>
<entry>
<title>Merge tag 'irq-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2022-05-23T23:58:49Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-05-23T23:58:49Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=fcfde8a7cf6d5e347ce61d8e5c0aee52926ef8e9'/>
<id>urn:sha1:fcfde8a7cf6d5e347ce61d8e5c0aee52926ef8e9</id>
<content type='text'>
Pull interrupt handling updates from Thomas Gleixner:
 "Core code:

   - Make the managed interrupts more robust by shutting them down in
     the core code when the assigned affinity mask does not contain
     online CPUs.

   - Make the irq simulator chip work on RT

   - A small set of cpumask and power manageent cleanups

  Drivers:

   - A set of changes which mark GPIO interrupt chips immutable to
     prevent the GPIO subsystem from modifying it under the hood. This
     provides the necessary infrastructure and converts a set of GPIO
     and pinctrl drivers over.

   - A set of changes to make the pseudo-NMI handling for GICv3 more
     robust: a missing barrier and consistent handling of the priority
     mask.

   - Another set of GICv3 improvements and fixes, but nothing
     outstanding

   - The usual set of improvements and cleanups all over the place

   - No new irqchip drivers and not even a new device tree binding!
     100+ interrupt chips are truly enough"

* tag 'irq-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (39 commits)
  irqchip: Add Kconfig symbols for sunxi drivers
  irqchip/gic-v3: Fix priority mask handling
  irqchip/gic-v3: Refactor ISB + EOIR at ack time
  irqchip/gic-v3: Ensure pseudo-NMIs have an ISB between ack and handling
  genirq/irq_sim: Make the irq_work always run in hard irq context
  irqchip/armada-370-xp: Do not touch Performance Counter Overflow on A375, A38x, A39x
  irqchip/gic: Improved warning about incorrect type
  irqchip/csky: Return true/false (not 1/0) from bool functions
  irqchip/imx-irqsteer: Add runtime PM support
  irqchip/imx-irqsteer: Constify irq_chip struct
  irqchip/armada-370-xp: Enable MSI affinity configuration
  irqchip/aspeed-scu-ic: Fix irq_of_parse_and_map() return value
  irqchip/aspeed-i2c-ic: Fix irq_of_parse_and_map() return value
  irqchip/sun6i-r: Use NULL for chip_data
  irqchip/xtensa-mx: Fix initial IRQ affinity in non-SMP setup
  irqchip/exiu: Fix acknowledgment of edge triggered interrupts
  irqchip/gic-v3: Claim iomem resources
  dt-bindings: interrupt-controller: arm,gic-v3: Make the v2 compat requirements explicit
  irqchip/gic-v3: Relax polling of GIC{R,D}_CTLR.RWP
  irqchip/gic-v3: Detect LPI invalidation MMIO registers
  ...
</content>
</entry>
<entry>
<title>ARM: 9204/2: module: Add all unwind tables when load module</title>
<updated>2022-05-20T11:34:55Z</updated>
<author>
<name>Chen Zhongjin</name>
<email>chenzhongjin@huawei.com</email>
</author>
<published>2022-05-20T07:49:55Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=b6f21d14f1ac1261579b691673a0c823275cbaf8'/>
<id>urn:sha1:b6f21d14f1ac1261579b691673a0c823275cbaf8</id>
<content type='text'>
For EABI stack unwinding, when loading .ko module
the EXIDX sections will be added to a unwind_table list.

However not all EXIDX sections are added because EXIDX
sections are searched by hardcoded section names.

For functions in other sections such as .ref.text
or .kprobes.text, gcc generates seprated EXIDX sections
(such as .ARM.exidx.ref.text or .ARM.exidx.kprobes.text).

These extra EXIDX sections are not loaded, so when unwinding
functions in these sections, we will failed with:

	unwind: Index not found xxx

To fix that, I refactor the code for searching and adding
EXIDX sections:

- Check section type to search EXIDX tables (0x70000001)
instead of strcmp() the hardcoded names. Then find the
corresponding text sections by their section names.

- Add a unwind_table list in module-&gt;arch to save their own
unwind_table instead of the fixed-lenth array.

- Save .ARM.exidx.init.text section ptr, because it should
be cleaned after module init.

Now all EXIDX sections of .ko can be added correctly.

Signed-off-by: Chen Zhongjin &lt;chenzhongjin@huawei.com&gt;
Acked-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Signed-off-by: Russell King (Oracle) &lt;rmk+kernel@armlinux.org.uk&gt;
</content>
</entry>
<entry>
<title>ARM: 9195/1: entry: avoid explicit literal loads</title>
<updated>2022-05-20T11:32:32Z</updated>
<author>
<name>Ard Biesheuvel</name>
<email>ardb@kernel.org</email>
</author>
<published>2022-04-20T08:41:31Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=508074607c7b95b24f0adf633fdf606761bb7824'/>
<id>urn:sha1:508074607c7b95b24f0adf633fdf606761bb7824</id>
<content type='text'>
ARMv7 has MOVW/MOVT instruction pairs to load symbol addresses into
registers without having to rely on literal loads that go via the
D-cache.  For older cores, we now support a similar arrangement, based
on PC-relative group relocations.

This means we can elide most literal loads entirely from the entry path,
by switching to the ldr_va macro to emit the appropriate sequence
depending on the target architecture revision.

While at it, switch to the bl_r macro for invoking the right PABT/DABT
helpers instead of setting the LR register explicitly, which does not
play well with cores that speculate across function returns.

Signed-off-by: Ard Biesheuvel &lt;ardb@kernel.org&gt;
Reviewed-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Signed-off-by: Russell King (Oracle) &lt;rmk+kernel@armlinux.org.uk&gt;
</content>
</entry>
<entry>
<title>ARM: 9194/1: assembler: simplify ldr_this_cpu for !SMP builds</title>
<updated>2022-05-20T11:32:32Z</updated>
<author>
<name>Ard Biesheuvel</name>
<email>ardb@kernel.org</email>
</author>
<published>2022-04-20T08:38:27Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=952f03316352c606bebef56ba8f9642edbb8e348'/>
<id>urn:sha1:952f03316352c606bebef56ba8f9642edbb8e348</id>
<content type='text'>
When CONFIG_SMP is not defined, the CPU offset is always zero, and so
we can simplify the sequence to load a per-CPU variable.

Signed-off-by: Ard Biesheuvel &lt;ardb@kernel.org&gt;
Reviewed-by: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Signed-off-by: Russell King (Oracle) &lt;rmk+kernel@armlinux.org.uk&gt;
</content>
</entry>
<entry>
<title>irqchip/gic-v3: Refactor ISB + EOIR at ack time</title>
<updated>2022-05-15T15:38:25Z</updated>
<author>
<name>Mark Rutland</name>
<email>mark.rutland@arm.com</email>
</author>
<published>2022-05-13T13:30:37Z</published>
<link rel='alternate' type='text/html' href='https://git.zx2c4.com/linux-dev/commit/?id=6efb50923771f392122f5ce69dfc43b08f16e449'/>
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There are cases where a context synchronization event is necessary
between an IRQ being raised and being handled, and there are races such
that we cannot rely upon the exception entry being subsequent to the
interrupt being raised. To fix this, we place an ISB between a read of
IAR and the subsequent invocation of an IRQ handler.

When EOI mode 1 is in use, we need to EOI an interrupt prior to invoking
its handler, and we have a write to EOIR for this. As this write to EOIR
requires an ISB, and this is provided by the gic_write_eoir() helper, we
omit the usual ISB in this case, with the logic being:

|	if (static_branch_likely(&amp;supports_deactivate_key))
|		gic_write_eoir(irqnr);
|	else
|		isb();

This is somewhat opaque, and it would be a little clearer if there were
an unconditional ISB, with only the write to EOIR being conditional,
e.g.

|	if (static_branch_likely(&amp;supports_deactivate_key))
|		write_gicreg(irqnr, ICC_EOIR1_EL1);
|
|	isb();

This patch rewrites the code that way, with this logic factored into a
new helper function with comments explaining what the ISB is for, as
were originally laid out in commit:

  39a06b67c2c1256b ("irqchip/gic: Ensure we have an ISB between ack and -&gt;handle_irq")

Note that since then, we removed the IAR polling in commit:

  342677d70ab92142 ("irqchip/gic-v3: Remove acknowledge loop")

... which removed one of the two race conditions.

For consistency, other portions of the driver are made to manipulate
EOIR using write_gicreg() and explcit ISBs, and the gic_write_eoir()
helper function is removed.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland &lt;mark.rutland@arm.com&gt;
Cc: Marc Zyngier &lt;maz@kernel.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Will Deacon &lt;will.deacon@arm.com&gt;
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
Link: https://lore.kernel.org/r/20220513133038.226182-3-mark.rutland@arm.com
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