From: Oleg Nesterov <oleg@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>,
jan.kratochvil@redhat.com, linux-kernel@vger.kernel.org,
torvalds@linux-foundation.org, akpm@linux-foundation.org,
indan@nul.nu
Subject: Re: Ptrace documentation, draft #1
Date: Mon, 16 May 2011 19:48:14 +0200 [thread overview]
Message-ID: <20110516174814.GA21391@redhat.com> (raw)
In-Reply-To: <20110516172058.GD20624@htj.dyndns.org>
On 05/16, Tejun Heo wrote:
>
> On Mon, May 16, 2011 at 06:53:52PM +0200, Oleg Nesterov wrote:
> > > If you do GETSIGINFO and look at si->si_code, user generated signals
> > > can't have non-zero value there
> >
> > Hmm. The can? sys_kill() sets si_code = 0, but tkill() or queueinfo()
> > can pass any si_code < 0. Also, the kernel can generate the signal
> > with si_code > 0.
>
> Yeah, sure, not non-zero then, but it's still distinguishible, no?
Hmm. Now it is me who is missing context. And probably I misunderstood
the original question:
Kernel delivers an extra SIGTRAP to tracee after execve syscall
returns. This is an ordinary signal
...
??? can this SIGTRAP be distinguished from "real" user-generated SIGTRAP
by looking at its siginfo?
I meant, we can't distinguish this SIGTRAP. But if PTRACE_O_TRACEEXEC is
set then the tracee reports PTRACE_EVENT_EXEC, this is probably
distinguishible. IIUC, si_code > 0 if the tracee reports an event.
Oleg.
next prev parent reply other threads:[~2011-05-16 17:50 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-15 20:35 Ptrace documentation, draft #1 Denys Vlasenko
2011-05-16 9:15 ` Tejun Heo
2011-05-16 15:31 ` Oleg Nesterov
2011-05-16 15:52 ` Tejun Heo
2011-05-16 16:53 ` Oleg Nesterov
2011-05-16 17:20 ` Tejun Heo
2011-05-16 17:48 ` Oleg Nesterov [this message]
2011-05-18 15:02 ` Denys Vlasenko
2011-05-18 15:02 ` Denys Vlasenko
2011-05-19 19:49 ` Oleg Nesterov
2011-05-20 18:02 ` Denys Vlasenko
2011-05-23 12:10 ` Oleg Nesterov
2011-05-23 14:10 ` ptrace_resume->wake_up_process (Was: Ptrace documentation, draft #1) Oleg Nesterov
2011-05-23 16:17 ` Linus Torvalds
2011-05-23 17:23 ` Oleg Nesterov
2011-05-25 20:08 ` [GIT PULL] PTRACE_KILL/wakeup fix for v2.6.40 Oleg Nesterov
2011-05-23 17:05 ` [PATCH 0/2] Was: ptrace_resume->wake_up_process Oleg Nesterov
2011-05-23 17:05 ` [PATCH 1/2] ptrace: ptrace_resume() shouldn't wake up !TASK_TRACED thread Oleg Nesterov
2011-05-23 17:05 ` [PATCH 2/2] signal: sys_pause() should check signal_pending() Oleg Nesterov
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