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Date: Tue, 11 May 2004 10:07:22 -0400
From: Daniel Jacobowitz <dan@debian.org>
To: Davide Libenzi <davidel@xmailserver.org>
Cc: Fabiano Ramos <ramos_fabiano@yahoo.com.br>,
       OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>, Andi Kleen <ak@muc.de>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: ptrace in 2.6.5
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On Mon, May 10, 2004 at 11:41:53PM -0700, Davide Libenzi wrote:
> On Mon, 10 May 2004, Davide Libenzi wrote:
> 
> > On Mon, 10 May 2004, Davide Libenzi wrote:
> > 
> > > On the kernel side, this would be pretty much solved by issuing a ptrace 
> > > op, with a modified EIP (+2) on return from a syscall (if in single-step 
> > > mode).
> > 
> > Actaully, the EIP should not be changed (since it already points to the 
> > intruction following INT 0x80) and I believe it is sufficent to replace 
> > the test for _TIF_SYSCALL_TRACE with (_TIF_SYSCALL_TRACE | TIF_SINGLESTEP) 
> > in the system call return path. This should generate a ptrace trap with 
> > EIP pointing to the next instruction following INT 0x80.
> 
> The patch below (for i386) should work.

Yeah, that's what I was suggesting.  I think the patch is right.

-- 
Daniel Jacobowitz