From: Tejun Heo <tj@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
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 19:20:58 +0200 [thread overview]
Message-ID: <20110516172058.GD20624@htj.dyndns.org> (raw)
In-Reply-To: <20110516165352.GA18727@redhat.com>
Hello,
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?
> > so, if si->si_code contains SIGTRAP | PTRACE_EVENT_* << 8,
>
> But in this case (without PT_TRACE_EXEC) the tracee simply sends SIGTRAP
> to itself. It will be reported later like a normal signal.
Ah, okay, I missed the context. I thought we were talking about
GETSIGINFO after traps not the extra SIGTRAP after execve. Sorry
about that. :-)
> > Maybe we can remove these if SEIZED?
>
> Heh... I am not sure.
Yeah, I'm not sure either. I think the most reasonable solution would
be leaving them alone but strongly discourage their use.
> Hmm. What do you mean? tracehook_report_syscall_exit() can skip
> ptrace_report_syscall() if step, but this is another story. And in this
> case the tracee sends the real signal to itself, unlike
> tracehook_signal_handler() which does ptrace_notify().
Please disregard. Still was fixated on GETSIGINFO.
Thanks.
--
tejun
next prev parent reply other threads:[~2011-05-16 17:26 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 [this message]
2011-05-16 17:48 ` Oleg Nesterov
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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