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Date: Sun, 18 May 2008 13:31:41 +0200
From: "Vegard Nossum" <vegard.nossum@gmail.com>
To: "Andi Kleen" <andi@firstfloor.org>
Subject: Re: [PATCH] kmemcheck: support for x86_64
Cc: "Pekka Enberg" <penberg@cs.helsinki.fi>, "Ingo Molnar" <mingo@elte.hu>,
       linux-kernel@vger.kernel.org,
       "Arjan van de Ven" <arjan@linux.intel.com>
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On Sun, May 18, 2008 at 12:17 PM, Andi Kleen <andi@firstfloor.org> wrote:
>
>> Most of them look something like this:
>>
>> kmemcheck: Caught 8-bit read from freed memory (ffff81000780a904)
>> ifffffffifffffffifffffffifffffffifffffffifffffffifffffffifffffff
>>     ^
>>
>> and my theory so far is that X86_64 uses some currently unhandled
>> instruction set extensions like MMX, SSE, etc. (Not 3DNow! because we
>> have a dependency for that), for a fairly common operation
>
> No it shouldn't. Only SSE users are in the (broken) MD RAID code
>
> Most likely you don't decode REX correctly in some cases.

Thanks. You are right, but you are wrong.

All those #ifdef X86_64 should of course be CONFIG_X86_64... So none
of the 64-bit code was being compiled in. Good spotting, Vegard! :-(


Vegard

-- 
"The animistic metaphor of the bug that maliciously sneaked in while
the programmer was not looking is intellectually dishonest as it
disguises that the error is the programmer's own creation."
	-- E. W. Dijkstra, EWD1036