linux-kernel - Re: [PATCH] x86, kasan: add KASAN checks to atomic operations

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Date:   Wed, 8 Mar 2017 15:48:55 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     Will Deacon <will.deacon@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Ingo Molnar <mingo@...hat.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH] x86, kasan: add KASAN checks to atomic operations

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@....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@....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.