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From: Uros Bizjak <ubizjak@gmail.com>
Date: Wed, 10 Apr 2024 13:21:23 +0200
Message-ID: <CAFULd4aJd6YKXZr=AZ7yzNkiR4_DfL5soQSvhMhNiQEPUOS87g@mail.gmail.com>
Subject: Re: [PATCH 4/4] x86/percpu: Use C for percpu read/write accessors
To: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>, x86@kernel.org, 
	linux-kernel@vger.kernel.org, Andy Lutomirski <luto@kernel.org>, 
	Nadav Amit <namit@vmware.com>, Brian Gerst <brgerst@gmail.com>, 
	Denys Vlasenko <dvlasenk@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>, 
	Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>, 
	Borislav Petkov <bp@alien8.de>, Josh Poimboeuf <jpoimboe@redhat.com>, 
	Andrey Ryabinin <ryabinin.a.a@gmail.com>, Alexander Potapenko <glider@google.com>, 
	Dmitry Vyukov <dvyukov@google.com>, kasan-dev@googlegroups.com
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On Wed, Apr 10, 2024 at 1:11=E2=80=AFPM Andrey Konovalov <andreyknvl@gmail.=
com> wrote:
>
> On Mon, Oct 9, 2023 at 4:35=E2=80=AFPM Uros Bizjak <ubizjak@gmail.com> wr=
ote:
> >
> > On Mon, Oct 9, 2023 at 1:41=E2=80=AFPM Ingo Molnar <mingo@kernel.org> w=
rote:
> > >
> > >
> > > * Uros Bizjak <ubizjak@gmail.com> wrote:
> > >
> > > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > > > index ecb256954351..1edf4a5b93ca 100644
> > > > --- a/arch/x86/Kconfig
> > > > +++ b/arch/x86/Kconfig
> > > > @@ -2393,7 +2393,7 @@ config CC_HAS_NAMED_AS
> > > >
> > > >  config USE_X86_SEG_SUPPORT
> > > >       def_bool y
> > > > -     depends on CC_HAS_NAMED_AS && SMP
> > > > +     depends on CC_HAS_NAMED_AS && SMP && !KASAN
> > > > +     depends on CC_HAS_NAMED_AS && SMP && !KASAN
> > >
> > > So I'd rather express this as a Kconfig quirk line, and explain each =
quirk.
> > >
> > > Something like:
> > >
> > >         depends on CC_HAS_NAMED_AS
> > >         depends on SMP
> > >         #
> > >         # -fsanitize=3Dkernel-address (KASAN) is at the moment incomp=
atible
> > >         # with named address spaces - see GCC bug #12345.
> > >         #
> > >         depends on !KASAN
> >
> > This is now PR sanitizer/111736 [1], but perhaps KASAN people [CC'd]
> > also want to be notified about this problem.
> >
> > [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111736
>
> Filed a KASAN bug to track this:
> https://bugzilla.kernel.org/show_bug.cgi?id=3D218703

Please note the fix in -tip tree that reenables sanitizers for fixed compil=
ers:

https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=3Dx86=
/percpu&id=3D9ebe5500d4b25ee4cde04eec59a6764361a60709

Thanks,
Uros.