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From:   Marco Elver <elver@google.com>
Date:   Thu, 4 Jun 2020 07:59:42 +0200
Message-ID: <CANpmjNMoOOr1irxkGHz9S+dP4M4h+mpGu_Ve6tmaGDb0zN-bMw@mail.gmail.com>
Subject: Re: [PATCH -tip 1/2] Kconfig: Bump required compiler version of KASAN
 and UBSAN
To:     Andrey Konovalov <andreyknvl@google.com>
Cc:     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>,
        kasan-dev <kasan-dev@googlegroups.com>,
        LKML <linux-kernel@vger.kernel.org>
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On Wed, 3 Jun 2020 at 15:35, 'Andrey Konovalov' via kasan-dev
<kasan-dev@googlegroups.com> wrote:
>
> On Tue, Jun 2, 2020 at 8:44 PM Marco Elver <elver@google.com> wrote:
> >
> > Adds config variable CC_HAS_WORKING_NOSANITIZE, which will be true if we
> > have a compiler that does not fail builds due to no_sanitize functions.
> > This does not yet mean they work as intended, but for automated
> > build-tests, this is the minimum requirement.
> >
> > For example, we require that __always_inline functions used from
> > no_sanitize functions do not generate instrumentation. On GCC <= 7 this
> > fails to build entirely, therefore we make the minimum version GCC 8.
> >
> > For KCSAN this is a non-functional change, however, we should add it in
> > case this variable changes in future.
> >
> > Link: https://lkml.kernel.org/r/20200602175859.GC2604@hirez.programming.kicks-ass.net
> > Suggested-by: Peter Zijlstra <peterz@infradead.org>
> > Signed-off-by: Marco Elver <elver@google.com>
>
> Acked-by:  Andrey Konovalov <andreyknvl@google.com>

I've sent a v2 of this, which limits the compiler-bump to KASAN only.
It appears no_sanitize_undefined (for UBSAN) is not broken GCC <= 7,
and in general the no_sanitize attributes seem to behave differently
from sanitizer to sanitizer as we discovered for UBSAN.

https://lkml.kernel.org/r/20200604055811.247298-1-elver@google.com