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Date:   Wed, 29 May 2019 11:58:15 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Marco Elver <elver@google.com>
Cc:     Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@google.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        the arch/x86 maintainers <x86@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-arch <linux-arch@vger.kernel.org>,
        kasan-dev <kasan-dev@googlegroups.com>
Subject: Re: [PATCH 2/3] tools/objtool: add kasan_check_* to uaccess whitelist
Message-ID: <20190529095815.GL2623@hirez.programming.kicks-ass.net>
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On Wed, May 29, 2019 at 11:46:10AM +0200, Marco Elver wrote:
> On Wed, 29 May 2019 at 10:55, Dmitry Vyukov <dvyukov@google.com> wrote:
> >
> > On Tue, May 28, 2019 at 7:19 PM Peter Zijlstra <peterz@infradead.org> wrote:
> > >
> > > On Tue, May 28, 2019 at 06:32:57PM +0200, Marco Elver wrote:
> > > > This is a pre-requisite for enabling bitops instrumentation. Some bitops
> > > > may safely be used with instrumentation in uaccess regions.
> > > >
> > > > For example, on x86, `test_bit` is used to test a CPU-feature in a
> > > > uaccess region:   arch/x86/ia32/ia32_signal.c:361
> > >
> > > That one can easily be moved out of the uaccess region. Any else?
> >
> > Marco, try to update config with "make allyesconfig" and then build
> > the kernel without this change.
> >
> 
> Done. The only instance of the uaccess warning is still in
> arch/x86/ia32/ia32_signal.c.
> 
> Change the patch to move this access instead? Let me know what you prefer.

Yes, I think that might be best. The whitelist should be minimal.