From: Andi Kleen <ak@muc.de>
To: Fabiano Ramos <ramos_fabiano@yahoo.com.br>
Cc: linux-kernel@vger.kernel.org
Subject: Re: ptrace in 2.6.5
Date: Mon, 10 May 2004 20:49:39 +0200 [thread overview]
Message-ID: <m365b4kth8.fsf@averell.firstfloor.org> (raw)
In-Reply-To: <1UlcA-6lq-9@gated-at.bofh.it> (Fabiano Ramos's message of "Mon, 10 May 2004 17:50:08 +0200")
Fabiano Ramos <ramos_fabiano@yahoo.com.br> writes:
> Hi All.
>
> Is ptrace(), in singlestep mode, required to stop after a int 0x80?
> When tracing a sequence like
>
> mov ...
> int 0x80
> mov ....
>
> ptrace would notify the tracer after the two movs, but not after the
> int 0x80. I want to know if it is a bug or the expected behaviour.
What happens is that after the int 0x80 the CPU is in ring 0 (you
don't get an trace event in that mode unless you use a kernel debugger).
Then when the kernel returns the last instruction executed before it is an
IRET. But the IRET is also executed still in ring 0 and you should not get
an event for it (you can not even access its code from user space).
So it's expected behaviour.
-Andi
next parent reply other threads:[~2004-05-10 18:49 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1UlcA-6lq-9@gated-at.bofh.it>
2004-05-10 18:49 ` Andi Kleen [this message]
2004-05-10 19:37 ` ptrace in 2.6.5 Davide Libenzi
2004-05-10 20:24 ` Fabiano Ramos
2004-05-10 21:49 ` OGAWA Hirofumi
2004-05-10 22:47 ` OGAWA Hirofumi
2004-05-10 22:58 ` Daniel Jacobowitz
2004-05-10 23:12 ` Davide Libenzi
2004-05-11 0:40 ` Fabiano Ramos
2004-05-11 6:14 ` Davide Libenzi
2004-05-11 6:27 ` Davide Libenzi
2004-05-11 6:41 ` Davide Libenzi
2004-05-11 14:07 ` Daniel Jacobowitz
2004-05-10 15:46 Fabiano Ramos
2004-05-10 16:10 ` Daniel Jacobowitz
2004-05-10 16:22 ` Fabiano Ramos
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