From: Josh Stone <jistone@redhat.com>
To: Yao Qi <qiyaoltc@gmail.com>
Cc: Pedro Alves <palves@redhat.com>,
gdb-patches@sourceware.org, philippe.waroquiers@skynet.be,
sergiodj@redhat.com, eliz@gnu.org, xdje42@gmail.com,
scox@redhat.com
Subject: Re: [PATCH v4] Implement 'catch syscall' for gdbserver
Date: Fri, 01 Apr 2016 16:38:00 -0000 [thread overview]
Message-ID: <56FEA3EB.9060306@redhat.com> (raw)
In-Reply-To: <86bn5tqy29.fsf@gmail.com>
On 04/01/2016 06:05 AM, Yao Qi wrote:
> Josh Stone <jistone@redhat.com> writes:
>
>> Well, sure, but I have no idea where that somewhere else could be.
>>
>> Note these architectures do work for other syscall returns. It's just
>> that execve is a bit special by switching the whole process out.
>
> I talked with a kernel people, looks GDB can't fetch the syscall number
> on execve exit.
>
>>
>> I suppose we could try to save the number on syscall entry, and just
>> report that again when it returns. But it's not 100% sure that we'll
>
> Yes, that is what I am thinking too.
I guess then it's a question whether we try to save this as much as
possible, or only for cases that look like execve (on entry).
>> see every entry first. For instance, one could 'catch execve' first,
>> which will continue until PTRACE_EVENT_EXEC mid-syscall, then turn on
>> 'catch syscall' and see what returns.
>> (This is similar to what test_catch_syscall_mid_vfork checks.)
>
> Yeah, we can't guarantee syscall enter comes into first. I doubt
> 'lp->syscall_state' is confused in this case too, no?
This is one of the things I fixed. We know that events like
PTRACE_EVENT_EXEC are mid-syscall, even if we didn't see the entry, so a
syscall event that follows must be a return. And other ptrace stops are
never mid-syscall, so a syscall that follows those must be an entry.
This is set in linux_handle_extended_wait and wait_lwp.
next prev parent reply other threads:[~2016-04-01 16:38 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-30 11:02 [PATCH] " Josh Stone
2015-10-30 13:26 ` Eli Zaretskii
2015-11-01 22:15 ` Doug Evans
2015-11-02 18:24 ` Josh Stone
2015-11-21 10:29 ` Philippe Waroquiers
2015-11-23 4:20 ` Doug Evans
2015-11-23 4:20 ` Doug Evans
2015-11-25 2:37 ` Josh Stone
2015-11-26 2:53 ` [PATCH v2 1/2] gdbserver: Set Linux ptrace options ASAP Josh Stone
2015-11-26 2:54 ` [PATCH v2 2/2] Implement 'catch syscall' for gdbserver Josh Stone
2015-11-26 10:34 ` [PATCH v2 1/2] gdbserver: Set Linux ptrace options ASAP Pedro Alves
2015-11-30 18:50 ` Josh Stone
2015-12-01 20:17 ` Josh Stone
2015-12-02 14:01 ` Pedro Alves
2015-12-04 2:26 ` [PATCH v3 1/2] gdbserver: set ptrace flags after creating inferiors Josh Stone
2015-12-04 2:27 ` [PATCH v3 2/2] Implement 'catch syscall' for gdbserver Josh Stone
2015-12-04 8:45 ` Eli Zaretskii
2015-12-05 2:14 ` Josh Stone
2015-12-05 8:02 ` Eli Zaretskii
2015-12-07 16:50 ` Josh Stone
2015-12-07 17:15 ` Eli Zaretskii
2015-12-04 13:18 ` Pedro Alves
2015-12-05 2:16 ` Josh Stone
2015-12-08 13:31 ` Pedro Alves
2015-12-08 19:02 ` Josh Stone
2015-12-08 13:37 ` Pedro Alves
2015-12-11 21:19 ` Josh Stone
2015-12-16 15:42 ` Pedro Alves
2016-01-09 3:09 ` [PATCH v4] " Josh Stone
2016-01-09 7:37 ` Eli Zaretskii
2016-01-11 17:44 ` Philippe Waroquiers
2016-01-12 12:05 ` Pedro Alves
2016-01-12 19:10 ` Josh Stone
2016-01-12 19:22 ` Pedro Alves
2016-01-12 20:01 ` Josh Stone
2016-03-29 14:27 ` Yao Qi
2016-03-29 18:12 ` Josh Stone
2016-03-29 23:49 ` Josh Stone
2016-03-30 12:23 ` Yao Qi
2016-03-31 1:10 ` Josh Stone
2016-04-01 13:05 ` Yao Qi
2016-04-01 16:38 ` Josh Stone [this message]
2016-05-29 16:47 ` [doc] NEWS: QCatchSyscalls: simplify Jan Kratochvil
2016-05-29 17:29 ` Eli Zaretskii
2016-05-29 17:50 ` Jan Kratochvil
2016-05-29 18:19 ` Eli Zaretskii
2016-05-29 18:47 ` [commit] " Jan Kratochvil
2015-12-04 12:16 ` [PATCH v3 1/2] gdbserver: set ptrace flags after creating inferiors Pedro Alves
2015-12-05 2:14 ` Josh Stone
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