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Date: Wed, 3 Oct 2007 17:49:14 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Greg KH <gregkh@suse.de>, Alexander Viro <viro@ftp.linux.org.uk>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [bug] crash when reading /proc/mounts (was: Re: Linux
	2.6.23-rc9 and a heads-up for the 2.6.24 series..)
Message-ID: <20071003154914.GA21690@elte.hu>
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> Your compiler generates
> 
> 	movl    -16(%ebp),%edx
> 	movl    (%edx),%edi		/* this is _totally_ bogus! */
> 	incl    %edx
> 	movl    %edx,-16(%ebp)
> 	movl    %edi,%ecx
> 	testb   %cl,%cl
> 	je      ...

ah, ok.

> while I get (gcc version 4.1.2 20070925 (Red Hat 4.1.2-28)):
> 
>         movl    -16(%ebp), %eax # p,
>         movzbl  (%eax), %edi    #, c	/* not bogus! */
>         movl    %edi, %edx      # c,
>         testb   %dl, %dl        #
>         je      .L64    #,
>         incl    %eax    #
>         movsbl  %dl,%ebx        #, D.12414
>         movl    %eax, -16(%ebp) #, p
> 
> where the difference (apart from doing the increment differently and 
> different register allocation) is that I have a "movzbl" (correct), 
> while you have a "movl" (pure and utter crap).

i'll try with another compiler in a minute.

	Ingo
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