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From:   Marco Elver <elver@google.com>
Date:   Tue, 2 Jun 2020 20:55:37 +0200
Message-ID: <CANpmjNMeAhS9vemP=OOPBmj_9dDnmQ=nxXARHeOQnw8z-uZS7Q@mail.gmail.com>
Subject: Re: [PATCH -tip 2/2] compiler_types.h: Add __no_sanitize_{address,undefined}
 to noinstr
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
        Will Deacon <will@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Borislav Petkov <bp@alien8.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Dmitry Vyukov <dvyukov@google.com>,
        Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@google.com>,
        kasan-dev <kasan-dev@googlegroups.com>,
        LKML <linux-kernel@vger.kernel.org>,
        syzbot <syzbot+dc1fa714cb070b184db5@syzkaller.appspotmail.com>
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On Tue, 2 Jun 2020 at 20:49, 'Nick Desaulniers' via kasan-dev
<kasan-dev@googlegroups.com> wrote:
>
> On Tue, Jun 2, 2020 at 11:44 AM 'Marco Elver' via Clang Built Linux
> <clang-built-linux@googlegroups.com> wrote:
> >
> > Adds the portable definitions for __no_sanitize_address, and
> > __no_sanitize_undefined, and subsequently changes noinstr to use the
> > attributes to disable instrumentation via KASAN or UBSAN.
> >
> > Link: https://lore.kernel.org/lkml/000000000000d2474c05a6c938fe@google.com/
> > Reported-by: syzbot+dc1fa714cb070b184db5@syzkaller.appspotmail.com
> > Signed-off-by: Marco Elver <elver@google.com>
>
> Currently most of our compiler attribute detection is done in
> include/linux/compiler_attributes.h; I think this should be handled
> there. +Miguel Ojeda

GCC and Clang define these very differently, and the way to query for
them is different too. All we want is a portable __no_sanitize, and
compiler-{gcc,clang}.h is the right place for that. Similar to why we
define the other __no_sanitize above the places they were added.

Thanks,
-- Marco