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  1. 25 Jul, 2018 5 commits
    • Mark Rutland's avatar
      locking/atomics: Rework ordering barriers · fd2efaa4
      Mark Rutland authored 
      Currently architectures can override __atomic_op_*() to define the barriers
used before/after a relaxed atomic when used to build acquire/release/fence
variants.

This has the unfortunate property of requiring the architecture to define the
full wrapper for the atomics, rather than just the barriers they care about,
and gets in the way of generating atomics which can be easily read.

Instead, this patch has architectures define an optional set of barriers:

* __atomic_acquire_fence()
* __atomic_release_fence()
* __atomic_pre_full_fence()
* __atomic_post_full_fence()

... which <linux/atomic.h> uses to build the wrappers.

It would be nice if we could undef these, along with the __atomic_op_*()
wrappers, but that would break the cmpxchg() wrappers, which are written
in preprocessor. Undefs would have been nice, but alas.

There should be no functional change as a result of this patch.
Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Cc: Andrea Parri <parri.andrea@gmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andy.shevchenko@gmail.com
Cc: arnd@arndb.de
Cc: aryabinin@virtuozzo.com
Cc: catalin.marinas@arm.com
Cc: dvyukov@google.com
Cc: glider@google.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: peter@hurleysoftware.com
Link: http://lkml.kernel.org/r/20180716113017.3909-7-mark.rutland@arm.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      fd2efaa4
    • Mark Rutland's avatar
      locking/atomics: Instrument cmpxchg_double*() · 4d2b25f6
      Mark Rutland authored 
      We currently don't instrument cmpxchg_double() and
cmpxchg_double_local() due to compilation issues reported in the past,
which are supposedly related to GCC bug 72873 [1], reported when GCC 7
was not yet released. This bug only applies to x86-64, and does not
apply to other architectures.

While the test case for GCC bug 72873 triggers issues with released
versions of GCC, the instrumented kernel code compiles fine for all
configurations I have tried, and it is unclear how the two cases
are/were related.

As we can't reproduce the kernel build failures, let's instrument
cmpxchg_double*() again. We can revisit the issue if build failures
reappear.
Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andy.shevchenko@gmail.com
Cc: aryabinin@virtuozzo.com
Cc: catalin.marinas@arm.com
Cc: glider@google.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: parri.andrea@gmail.com
Cc: peter@hurleysoftware.com
Link: http://lkml.kernel.org/r/20180716113017.3909-6-mark.rutland@arm.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      4d2b25f6
    • Mark Rutland's avatar
      locking/atomics: Instrument xchg() · f9881cc4
      Mark Rutland authored 
      While we instrument all of the (non-relaxed) atomic_*() functions and
cmpxchg(), we missed xchg().

Let's add instrumentation for xchg(), fixing up x86 to implement
arch_xchg().
Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andy.shevchenko@gmail.com
Cc: arnd@arndb.de
Cc: aryabinin@virtuozzo.com
Cc: catalin.marinas@arm.com
Cc: glider@google.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: parri.andrea@gmail.com
Cc: peter@hurleysoftware.com
Link: http://lkml.kernel.org/r/20180716113017.3909-5-mark.rutland@arm.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      f9881cc4
    • Mark Rutland's avatar
      locking/atomics: Simplify cmpxchg() instrumentation · df79ed2c
      Mark Rutland authored 
      Currently we define some fairly verbose wrappers for the cmpxchg()
family so that we can pass a pointer and size into kasan_check_write().

The wrappers duplicate the size-switching logic necessary in arch code,
and only work for scalar types. On some architectures, (cmp)xchg are
used on non-scalar types, and thus the instrumented wrappers need to be
able to handle this.

We could take the type-punning logic from {READ,WRITE}_ONCE(), but this
makes the wrappers even more verbose, and requires several local
variables in the macros.

Instead, let's simplify the wrappers into simple macros which:

* snapshot the pointer into a single local variable, called __ai_ptr to
  avoid conflicts with variables in the scope of the caller.

* call kasan_check_write() on __ai_ptr.

* invoke the relevant arch_*() function, passing the original arguments,
  bar __ai_ptr being substituted for ptr.

There should be no functional change as a result of this patch.
Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: andy.shevchenko@gmail.com
Cc: arnd@arndb.de
Cc: aryabinin@virtuozzo.com
Cc: catalin.marinas@arm.com
Cc: glider@google.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: parri.andrea@gmail.com
Cc: peter@hurleysoftware.com
Link: http://lkml.kernel.org/r/20180716113017.3909-4-mark.rutland@arm.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      df79ed2c
    • Mark Rutland's avatar
      locking/atomics/x86: Reduce arch_cmpxchg64*() instrumentation · 00d5551c
      Mark Rutland authored 
      Currently x86's arch_cmpxchg64() and arch_cmpxchg64_local() are
instrumented twice, as they call into instrumented atomics rather than
their arch_ equivalents.

A call to cmpxchg64() results in:

  cmpxchg64()
    kasan_check_write()
    arch_cmpxchg64()
      cmpxchg()
        kasan_check_write()
        arch_cmpxchg()

Let's fix this up and call the arch_ equivalents, resulting in:

  cmpxchg64()
    kasan_check_write()
    arch_cmpxchg64()
      arch_cmpxchg()
Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: andy.shevchenko@gmail.com
Cc: arnd@arndb.de
Cc: aryabinin@virtuozzo.com
Cc: catalin.marinas@arm.com
Cc: glider@google.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: parri.andrea@gmail.com
Cc: peter@hurleysoftware.com
Link: http://lkml.kernel.org/r/20180716113017.3909-3-mark.rutland@arm.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      00d5551c
  3. 17 Jul, 2018 15 commits
  5. 15 Jul, 2018 2 commits
  7. 14 Jul, 2018 18 commits
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