linux-kernel - Re: Linux i386 clone(): %ebx 'frobbing' ?

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Message-ID: <20080215235405.GB8012@ubuntu>
Date:	Sat, 16 Feb 2008 01:54:05 +0200
From:	"Ahmed S. Darwish" <darwish.07@...il.com>
To:	Andreas Schwab <schwab@...e.de>
Cc:	libc-alpha@...rceware.org, libc-alpha@...rces.redhat.com,
	linux-kernel@...r.kernel.org
Subject: Re: Linux i386 clone(): %ebx 'frobbing' ?

On Sat, Feb 16, 2008 at 12:28:11AM +0100, Andreas Schwab wrote:
> "Ahmed S. Darwish" <darwish.07@...il.com> writes:
> 
> > Hi Andreas,
> >
> > On Fri, Feb 15, 2008, Andreas Schwab wrote:
> >> "Ahmed S. Darwish" <darwish.07@...il.com> writes:
> >> 
> >> > I don't understand how the `fn' argument reached the child thread
> >> > in the %ebx register. It's said in the comment that `fn' will be
> >> > popped to child 'in the ebx frobbing below'. But what does that mean ?
> >> 
> >> See "popl %ebx" after "int $0x80".
> >> 
> >
> > I hope I'm not misreading something obvious, but I can't find
> > the code where FUNC(%esp) is stored in %ebx before %ebx value
> > got pushed in the stack (and restored in above 'popl' statement).
> 
> It is stored in the new stack for the child, as explained in the
> comment.  The parent has a different stack.
> 

Ooh great, I got it. Sorry, my mind didn't connect the dots though 
I read the comment several times. Thanks a lot for bearing with me :).

Regards,

-- 
Ahmed S. Darwish
Homepage: http://darwish.07.googlepages.com
Blog: http://darwish-07.blogspot.com

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