linux-kernel - Re: [PATCH 2/2] kasan: disallow compiler to optimize away memset in tests

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Date:   Fri, 2 Mar 2018 15:11:56 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Andrey Konovalov <andreyknvl@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Nick Terrell <terrelln@...com>, Chris Mason <clm@...com>,
        Yury Norov <ynorov@...iumnetworks.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        "Luis R . Rodriguez" <mcgrof@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
        Jeff Layton <jlayton@...hat.com>,
        "Jason A . Donenfeld" <Jason@...c4.com>,
        linux-kernel@...r.kernel.org, kasan-dev@...glegroups.com,
        linux-mm@...ck.org
Cc:     Kostya Serebryany <kcc@...gle.com>
Subject: Re: [PATCH 2/2] kasan: disallow compiler to optimize away memset in
 tests



On 03/01/2018 08:15 PM, Andrey Konovalov wrote:
> A compiler can optimize away memset calls by replacing them with mov
> instructions. There are KASAN tests, that specifically test that KASAN
> correctly handles memset calls, we don't want this optimization to
> happen.
> 
> The solution is to add -fno-builtin flag to test_kasan.ko
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>

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