From: Pedro Alves <palves@redhat.com>
To: Yao Qi <qiyaoltc@gmail.com>
Cc: gdb-patches@sourceware.org
Subject: Re: [PATCH v2 15/23] Implement all-stop on top of a target running non-stop mode
Date: Wed, 08 Apr 2015 11:08:00 -0000 [thread overview]
Message-ID: <55250C1D.4090304@redhat.com> (raw)
In-Reply-To: <5524FA77.50900@redhat.com>
On 04/08/2015 10:52 AM, Pedro Alves wrote:
> On 04/08/2015 10:34 AM, Yao Qi wrote:
>> Pedro Alves <palves@redhat.com> writes:
>>
>>> @@ -1997,7 +1998,7 @@ start_step_over_inferior (struct inferior *inf)
>>> {
>>> /* In all-stop, we shouldn't have resumed unless we needed a
>>> step over. */
>>> - gdb_assert (non_stop);
>>> + gdb_assert (target_is_non_stop_p ());
>>> }
>>> }
>>
>> Hi Pedro,
>> I tested the whole series on arm-linux and there is an assert triggered
>> with gdbserver,
>>
>> signal SIGTRAP^M
>> Continuing with signal SIGTRAP.^M
>> ../../../binutils-gdb/gdb/infrun.c:2008: internal-error: start_step_over_inferior: Assertion `target_is_non_stop_p ()' failed.^M
>> A problem internal to GDB has been detected,^M
>> further debugging may prove unreliable.^M
>> Quit this debugging session? (y or n) FAIL: gdb.threads/signal-sigtrap.exp: sigtrap thread 2: signal SIGTRAP reaches handler (GDB internal error)
>>
>> there is no such internal error in native testing. I haven't analyse it
>> carefully yet.
>
> Interesting. I hadn't tested gdbserver with the series applied on
> top of my x86-64 software single-step branch. But running signal-sigtrap.exp
> against that trips on that assert too. The test does passes cleanly against
> gdbserver with hardware single-step (x86-64). I'll take a look.
The issue is that the thread that we're starting a new step-over on
has a signal to deliver as well. So 'resume' reaches the:
/* Currently, our software single-step implementation leads to different
results than hardware single-stepping in one situation: when stepping
into delivering a signal which has an associated signal handler,
hardware single-step will stop at the first instruction of the handler,
while software single-step will simply skip execution of the handler.
... part. This clears trap_expected, which results in that assertion.
Hmm. Looks like the assertion caught a pre-existing problem.
This sets up the thread to re-hit the breakpoint at PC once the
signal handler returns, and lets _all_ threads run. But, what if had
_other_ threads that needed a step-over too? Those will run too,
and immediately re-trap the same breakpoint, but GDB will re-report them.
Maybe we should set a step-resume breakpoint on _all_ threads that need
a step-over, not just the current. I'll need to think a bit about this.
Thanks,
Pedro Alves
next prev parent reply other threads:[~2015-04-08 11:08 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-07 12:49 [PATCH v2 00/23] All-stop on top of non-stop Pedro Alves
2015-04-07 12:50 ` [PATCH v2 02/23] Fix and test "checkpoint" in non-stop mode Pedro Alves
2015-04-07 12:50 ` [PATCH v2 16/23] Fix signal-while-stepping-over-bp-other-thread.exp on targets always in non-stop Pedro Alves
2015-04-07 12:50 ` [PATCH v2 15/23] Implement all-stop on top of a target running non-stop mode Pedro Alves
2015-04-07 13:36 ` Eli Zaretskii
2015-04-08 9:34 ` Yao Qi
2015-04-08 9:53 ` Pedro Alves
2015-04-08 11:08 ` Pedro Alves [this message]
2015-04-08 19:35 ` Pedro Alves
2015-04-08 19:41 ` Pedro Alves
2015-04-07 12:50 ` [PATCH v2 22/23] S/390: displaced stepping and PC-relative RIL-b/RIL-c instructions Pedro Alves
2015-04-07 12:50 ` [PATCH v2 11/23] Use keep_going in proceed and start_step_over too Pedro Alves
2015-04-07 12:50 ` [PATCH v2 04/23] Change adjust_pc_after_break's prototype Pedro Alves
2015-04-07 12:50 ` [PATCH v2 12/23] Misc switch_back_to_stepped_thread cleanups Pedro Alves
2015-04-07 12:50 ` [PATCH v2 20/23] PPC64: symbol-file + exec-file results in broken displaced stepping Pedro Alves
2015-04-07 12:50 ` [PATCH v2 21/23] PPC64: Fix gdb.arch/ppc64-atomic-inst.exp with " Pedro Alves
2015-04-07 12:50 ` [PATCH v2 05/23] remote.c/all-stop: Implement TARGET_WAITKIND_NO_RESUMED and TARGET_WNOHANG Pedro Alves
2015-04-07 12:50 ` [PATCH v2 09/23] Make gdb.threads/step-over-trips-on-watchpoint.exp effective on !x86 Pedro Alves
2015-04-07 12:50 ` [PATCH v2 10/23] PPC64: Fix step-over-trips-on-watchpoint.exp with displaced stepping on Pedro Alves
2015-04-07 12:50 ` [PATCH v2 03/23] PR13858 - Can't do displaced stepping with no symbols Pedro Alves
2015-04-09 12:46 ` Pedro Alves
2015-04-07 12:50 ` [PATCH v2 01/23] Fix gdb.base/sigstep.exp with displaced stepping on software single-step targets Pedro Alves
2015-04-10 9:56 ` Pedro Alves
2015-04-07 12:50 ` [PATCH v2 19/23] Disable displaced stepping if trying it fails Pedro Alves
2015-04-07 12:50 ` [PATCH v2 23/23] native Linux: enable always non-stop by default Pedro Alves
2015-04-07 12:55 ` [PATCH v2 17/23] Fix interrupt-noterm.exp on targets always in non-stop Pedro Alves
2015-04-07 12:57 ` [PATCH v2 08/23] Test step-over-{lands-on-breakpoint|trips-on-watchpoint}.exp with displaced stepping Pedro Alves
2015-04-10 14:54 ` Pedro Alves
2015-04-07 12:59 ` [PATCH v2 13/23] Factor out code to re-resume stepped thread Pedro Alves
2015-04-07 12:59 ` [PATCH v2 07/23] Embed the pending step-over chain in thread_info objects Pedro Alves
2015-04-07 12:59 ` [PATCH v2 14/23] Teach non-stop to do in-line step-overs (stop all, step, restart) Pedro Alves
2015-04-07 13:30 ` [PATCH v2 18/23] Fix step-over-{trips-on-watchpoint|lands-on-breakpoint}.exp race Pedro Alves
2015-04-07 13:30 ` [PATCH v2 06/23] Make thread_still_needs_step_over consider stepping_over_watchpoint too Pedro Alves
2015-04-08 9:28 ` Yao Qi
2015-04-13 10:47 ` Pedro Alves
2015-04-08 9:45 ` [PATCH v2 00/23] All-stop on top of non-stop Yao Qi
2015-04-08 10:17 ` Pedro Alves
2015-04-08 10:30 ` Pedro Alves
2015-04-10 8:41 ` Yao Qi
2015-04-10 8:50 ` Pedro Alves
2015-04-10 8:22 ` Yao Qi
2015-04-10 8:34 ` Pedro Alves
2015-04-10 9:26 ` Yao Qi
2015-04-13 15:28 ` Pedro Alves
2015-04-13 16:16 ` Yao Qi
2015-04-13 16:23 ` Pedro Alves
2015-04-13 16:23 ` Pedro Alves
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=55250C1D.4090304@redhat.com \
--to=palves@redhat.com \
--cc=gdb-patches@sourceware.org \
--cc=qiyaoltc@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).