linux-kernel - Re: [PATCH v3 2/3] x86: Use static_cpu_has in uaccess region to avoid instrumentation

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Message-ID: <d3f70d55-0308-a2e2-0f4a-1bdf6bcde544@virtuozzo.com>
Date:   Thu, 13 Jun 2019 13:50:40 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Marco Elver <elver@...gle.com>, peterz@...radead.org,
        dvyukov@...gle.com, glider@...gle.com, andreyknvl@...gle.com,
        mark.rutland@....com, hpa@...or.com
Cc:     corbet@....net, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        x86@...nel.org, arnd@...db.de, jpoimboe@...hat.com,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org, kasan-dev@...glegroups.com
Subject: Re: [PATCH v3 2/3] x86: Use static_cpu_has in uaccess region to avoid
 instrumentation



On 5/31/19 6:08 PM, Marco Elver wrote:
> This patch is a pre-requisite for enabling KASAN bitops instrumentation;
> using static_cpu_has instead of boot_cpu_has avoids instrumentation of
> test_bit inside the uaccess region. With instrumentation, the KASAN
> check would otherwise be flagged by objtool.
> 
> For consistency, kernel/signal.c was changed to mirror this change,
> however, is never instrumented with KASAN (currently unsupported under
> x86 32bit).
> 
> Signed-off-by: Marco Elver <elver@...gle.com>
> Suggested-by: H. Peter Anvin <hpa@...or.com>

Reviewed-by: Andrey Ryabinin <aryabinin@...tuozzo.com>