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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Zachary Amsden <zach@vmware.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	davej@codemonkey.org.uk, hpa@zytor.com, bgerst@didntduck.org,
	Riley@Williams.Name
Subject: Re: PROBLEM: x86 alignment check bug
Date: Wed, 08 Sep 2004 14:26:35 +0100	[thread overview]
Message-ID: <1094649979.11678.28.camel@localhost.localdomain> (raw)
In-Reply-To: <413E498D.4020807@vmware.com>

On Mer, 2004-09-08 at 00:51, Zachary Amsden wrote:
> Exception reporting for alignment check violations on x86 is broken 
> (unfortunately, rather badly, and rather hard to fix).  Look at the trap 
> function which fills in the si_addr field during an unaligned memory 
> access, 2.6.8.1-mm4+, arch/i386/kernel/traps.c, Line 522:

So it fills in a value with random data that should be zero. Ok thats
hardly "badly". 

> Clearly, this is not correct.  Considering how difficult the fix is (the 
> kernel must disassemble the faulting instruction and use register 
> information to determine the faulting address)

It would be a nice extension although it would break other OS's if it
used %cr2 for this since they use it for thread id.



  parent reply	other threads:[~2004-09-08 14:29 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-09-07 23:51 PROBLEM: x86 alignment check bug Zachary Amsden
2004-09-08  0:08 ` David S. Miller
2004-09-08 12:12   ` Gabriel Paubert
2004-09-08 18:26     ` David S. Miller
2004-09-08 13:26 ` Alan Cox [this message]
  -- strict thread matches above, loose matches on Subject: below --
2004-09-09 16:29 Petr Vandrovec

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