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Date: Wed, 8 Mar 2017 15:48:55 +0000
From: Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH] x86, kasan: add KASAN checks to atomic operations
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To: Dmitry Vyukov <dvyukov@google.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 08, 2017 at 04:45:58PM +0100, Dmitry Vyukov wrote:
> 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().

... as above, that'd be handled by placing this in an
<asm-generic/atomic-instrumented.h> file, that we only include at the
end of the arch implementation.

So we'd only include that on arm64 and x86, without needing to change
the names elsewhere.

Thanks,
Mark.

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