Date: Tue, 11 Aug 2015 17:37:10 +0100
From: Catalin Marinas <catalin.marinas@arm.com>
To: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Will Deacon <will.deacon@arm.com>, linux-arm-kernel@lists.infradead.org,
        Yury <yury.norov@gmail.com>, Alexey Klimov <klimov.linux@gmail.com>,
        Arnd Bergmann <arnd@arndb.de>, linux-mm@kvack.org,
        Linus Walleij <linus.walleij@linaro.org>, linux-kbuild@vger.kernel.org,
        linux-kernel@vger.kernel.org, David Keitel <dkeitel@codeaurora.org>,
        Alexander Potapenko <glider@google.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
        Michal Marek <mmarek@suse.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH v5 5/6] arm64: add KASAN support
Message-ID: <20150811163709.GI23307@e104818-lin.cambridge.arm.com>
References: <1439259499-13913-1-git-send-email-ryabinin.a.a@gmail.com>
 <1439259499-13913-6-git-send-email-ryabinin.a.a@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1439259499-13913-6-git-send-email-ryabinin.a.a@gmail.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1780
Lines: 37

On Tue, Aug 11, 2015 at 05:18:18AM +0300, Andrey Ryabinin wrote:
> This patch adds arch specific code for kernel address sanitizer
> (see Documentation/kasan.txt).
> 
> 1/8 of kernel addresses reserved for shadow memory. There was no
> big enough hole for this, so virtual addresses for shadow were
> stolen from vmalloc area.
> 
> At early boot stage the whole shadow region populated with just
> one physical page (kasan_zero_page). Later, this page reused
> as readonly zero shadow for some memory that KASan currently
> don't track (vmalloc).
> After mapping the physical memory, pages for shadow memory are
> allocated and mapped.
> 
> Functions like memset/memmove/memcpy do a lot of memory accesses.
> If bad pointer passed to one of these function it is important
> to catch this. Compiler's instrumentation cannot do this since
> these functions are written in assembly.
> KASan replaces memory functions with manually instrumented variants.
> Original functions declared as weak symbols so strong definitions
> in mm/kasan/kasan.c could replace them. Original functions have aliases
> with '__' prefix in name, so we could call non-instrumented variant
> if needed.
> Some files built without kasan instrumentation (e.g. mm/slub.c).
> Original mem* function replaced (via #define) with prefixed variants
> to disable memory access checks for such files.
> 
> Signed-off-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
> Tested-by: Linus Walleij <linus.walleij@linaro.org>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/