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From: Dmitry Vyukov <dvyukov@google.com>
Date: Wed, 8 Mar 2017 16:45:58 +0100
Message-ID: <CACT4Y+ahGRxn7j8ZX=rTbwGm_eie-Wy81nKg9RGwjHzodFCK8g@mail.gmail.com>
Subject: Re: [PATCH] x86, kasan: add KASAN checks to atomic operations
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To: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>, Peter Zijlstra <peterz@infradead.org>, Andrew Morton <akpm@linux-foundation.org>, Andrey Ryabinin <aryabinin@virtuozzo.com>, Ingo Molnar <mingo@redhat.com>, kasan-dev <kasan-dev@googlegroups.com>, "linux-mm@kvack.org" <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, "x86@kernel.org" <x86@kernel.org>

On Wed, Mar 8, 2017 at 4:43 PM, Mark Rutland <mark.rutland@arm.com> wrote:
> On Wed, Mar 08, 2017 at 04:27:11PM +0100, Dmitry Vyukov wrote:
>> On Wed, Mar 8, 2017 at 4:20 PM, Mark Rutland <mark.rutland@arm.com> wrote:
>> > As in my other reply, I'd prefer that we wrapped the (arch-specific)
>> > atomic implementations such that we can instrument them explicitly in a
>> > core header. That means that the implementation and semantics of the
>> > atomics don't change at all.
>> >
>> > Note that we could initially do this just for x86 and arm64), e.g. by
>> > having those explicitly include an <asm-generic/atomic-instrumented.h>
>> > at the end of their <asm/atomic.h>.
>>
>> How exactly do you want to do this incrementally?
>> I don't feel ready to shuffle all archs, but doing x86 in one patch
>> and then arm64 in another looks tractable.
>
> I guess we'd have three patches: one adding the header and any core
> infrastructure, followed by separate patches migrating arm64 and x86
> over.

But if we add e.g. atomic_read() which forwards to arch_atomic_read()
to <linux/atomic.h>, it will break all archs that don't rename its
atomic_read() to arch_atomic_read().

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