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Date: Thu, 31 Aug 2017 10:31:47 +0100
From: Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH 1/3] kcov: support comparison operands collection
Message-ID: <20170831093146.GA15031@leverpostej>
References: <cover.1504109849.git.dvyukov@google.com>
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To: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, Victor Chibotaru <tchibo@google.com>, Alexander Popov <alex.popov@linux.com>, Andrey Ryabinin <aryabinin@virtuozzo.com>, Kees Cook <keescook@chromium.org>, Vegard Nossum <vegard.nossum@oracle.com>, Quentin Casasnovas <quentin.casasnovas@oracle.com>, syzkaller <syzkaller@googlegroups.com>, LKML <linux-kernel@vger.kernel.org>

On Wed, Aug 30, 2017 at 09:08:43PM +0200, Dmitry Vyukov wrote:
> On Wed, Aug 30, 2017 at 8:23 PM, Mark Rutland <mark.rutland@arm.com> wrote:
> > On Wed, Aug 30, 2017 at 06:23:29PM +0200, Dmitry Vyukov wrote:
> >> From: Victor Chibotaru <tchibo@google.com>
> >>
> >> Enables kcov to collect comparison operands from instrumented code.
> >> This is done by using Clang's -fsanitize=trace-cmp instrumentation
> >> (currently not available for GCC).

> >> Clang instrumentation:
> >> https://clang.llvm.org/docs/SanitizerCoverage.html#tracing-data-flow
> >
> > How stable is this?
> >
> > The comment at the end says "This interface is a subject to change."
> 
> The intention is that this is not subject to change anymore (since we
> are using it in kernel).
> I've mailed change to docs: https://reviews.llvm.org/D37303

Ok; thanks for confirming.

> FWIW, there is patch in flight that adds this instrumentation to gcc:
> https://groups.google.com/forum/#!topic/syzkaller/CSLynn6nI-A
> It seems to be stalled on review phase, though.

Let's hope it gets unblocked soon. :)

Thanks,
Mark.

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