From: Yao Qi <qiyaoltc@gmail.com>
To: Josh Stone <jistone@redhat.com>
Cc: Yao Qi <qiyaoltc@gmail.com>, 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: Wed, 30 Mar 2016 12:23:00 -0000 [thread overview]
Message-ID: <86io04rw7k.fsf@gmail.com> (raw)
In-Reply-To: <56FB1486.60208@redhat.com> (Josh Stone's message of "Tue, 29 Mar 2016 16:49:26 -0700")
Josh Stone <jistone@redhat.com> writes:
Hi Josh,
Thanks for the looking into this...
> So, it seems those architectures don't preserve their original syscall
> numbers across an execve.
>
> $ gdb -ex 'catch syscall execve' -ex 'run' -ex 'catch syscall' \
> -ex 'continue' --args sh -c /bin/true
>
> PPC64 and Aarch64 both read their syscall numbers from registers, and
> here they both get 0 ("restart_syscall" and "io_setup" respectively).
> S390X tries to decode it from the SVC instruction at PC-2, which will
> definitely fail after an execve -- gdb reports syscall -1.
I think it reveals a bug on getting syscall number. If the register
having syscall number isn't preserved across the syscall, GDB should
read syscall number somewhere else.
>
> So when the catchpoint is only for execve, they continue past this one
> since the number doesn't look like execve.
>
> The good news is that all three do call it a syscall *return*, which was
> the main point of this particular test. If there's no objection, I can
> try to update the test to work more like my command above, matching any
> syscall at all on the return side of execve.
--
Yao (齐尧)
next prev parent reply other threads:[~2016-03-30 12:23 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 [this message]
2016-03-31 1:10 ` Josh Stone
2016-04-01 13:05 ` Yao Qi
2016-04-01 16:38 ` Josh Stone
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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