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From:   Andy Lutomirski <luto@kernel.org>
Date:   Thu, 7 Mar 2019 11:06:57 -0800
Message-ID: <CALCETrWZ5MwPqFuwDkTKKZXnZivqdjtb9LhpgLpYk+iAagWyRw@mail.gmail.com>
Subject: Re: [PATCH 07/20] x86/uaccess: Always inline force_valid_ss()
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Julien Thierry <julien.thierry@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Ingo Molnar <mingo@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        James Morse <james.morse@arm.com>, valentin.schneider@arm.com,
        Brian Gerst <brgerst@gmail.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Andrew Lutomirski <luto@kernel.org>,
        Borislav Petkov <bp@alien8.de>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Dmitry Vyukov <dvyukov@google.com>,
        Steven Rostedt <rostedt@goodmis.org>
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On Thu, Mar 7, 2019 at 10:59 AM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Thu, Mar 07, 2019 at 10:05:43AM -0800, Andy Lutomirski wrote:
> > On Thu, Mar 7, 2019 at 3:52 AM Peter Zijlstra <peterz@infradead.org> wrote:
> > >
> > > arch/x86/kernel/signal.o: warning: objtool: restore_sigcontext()+0x3cc: call to force_valid_ss.isra.5() with UACCESS enabled
> > >
> > > XXX: move the callsite out of te AC=1 region instead?
> >
> > Let's move it instead.  I looked at the code and it should be fine.
>
> Something like so; or did I miss something subtle?

Reviewed-by: Andy Lutomirski <luto@kernel.org>

Also, this stuff is pretty well covered by the x86 selftests, mostly
because getting it right in the first place was way too subtle for
comfort.

--Andy