Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:5 as permitted sender) client-ip=2620:137:e000::3:5;
MIME-Version: 1.0
References: <20231004145137.86537-1-ubizjak@gmail.com> <20231004145137.86537-5-ubizjak@gmail.com>
 <CAHk-=wgepFm=jGodFQYPAaEvcBhR3-f_h1BLBYiVQsutCwCnUQ@mail.gmail.com>
 <CAFULd4YWjxoSTyCtMN0OzKgHtshMQOuMH1Z0n_OaWKVnUjy2iA@mail.gmail.com>
 <CAHk-=whq=+LNHmsde8LaF4pdvKxqKt5GxW+Tq+U35_aDcV0ADg@mail.gmail.com>
 <CAHk-=wi6U-O1wdPOESuCE6QO2OaPu0hEzaig0uDOU4L5CREhug@mail.gmail.com>
 <CAFULd4Z3C771u8Y==8h6hi=mhGmy=7RJRAEBGfNZ0SmynxF41g@mail.gmail.com> <ZSPm6Z/lTK1ZlO8m@gmail.com>
In-Reply-To: <ZSPm6Z/lTK1ZlO8m@gmail.com>
From:   Uros Bizjak <ubizjak@gmail.com>
Date:   Mon, 9 Oct 2023 14:27:34 +0200
Message-ID: <CAFULd4Yf9u2qvDyynDX3vSNNH+qCkxrpJocaKQnyH89sJLqHuA@mail.gmail.com>
Subject: Re: [PATCH 4/4] x86/percpu: Use C for percpu read/write accessors
To:     Ingo Molnar <mingo@kernel.org>
Cc:     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>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Mon, Oct 9, 2023 at 1:41=E2=80=AFPM Ingo Molnar <mingo@kernel.org> wrote=
:
>
>
> * 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 quir=
k.
>
> Something like:
>
>         depends on CC_HAS_NAMED_AS
>         depends on SMP
>         #
>         # -fsanitize=3Dkernel-address (KASAN) is at the moment incompatib=
le
>         # with named address spaces - see GCC bug #12345.
>         #
>         depends on !KASAN
>
> ... or so.
>
> BTW., please also document the reason why !SMP is excluded.

Eh, thanks for pointing it out, it is not needed at all, it works also
for !SMP. Will fix in a Kconfig patch.

Thanks,
Uros.