From: Yao Qi <qiyaoltc@gmail.com>
To: Antoine Tremblay <antoine.tremblay@ericsson.com>
Cc: "gdb-patches@sourceware.org" <gdb-patches@sourceware.org>
Subject: Re: [PATCH 1/2] This patch fixes GDBServer's run control for single stepping
Date: Fri, 27 Jan 2017 17:01:00 -0000 [thread overview]
Message-ID: <CAH=s-PP-i3v_Fr=QeWt9BQeJzjCHtW79nGYpJ9hF-Bb=OBo89Q@mail.gmail.com> (raw)
In-Reply-To: <wwokwpdg5vxa.fsf@ericsson.com>
On Fri, Jan 27, 2017 at 4:06 PM, Antoine Tremblay
<antoine.tremblay@ericsson.com> wrote:
>> GDB/GDBserver has to emulate the instruction on how does it affect the
>> flag, and only insert the breakpoint on the "true" branch. Since the
>> target instruction will be definitely executed, we can safely use
>> 16-bit breakpoint instruction.
>
> Ouch, reading the kernel thread it looks like this emulation would be
> complex to say the least.
>
There are some other ideas discussed in the kernel threads, but I didn't
go through them. They may work. If emulation is complex, probably
we can partially fix this problem by "always using 16-bit thumb instruction
if program is out of IT block".
> I think it would be better to get the current single stepping working
> with the stop all threads logic since GDBServer was working like that
> when GDB was doing the single stepping anyway. This would fix the current
> regression.
>
> Then work could be done to improve GDBServer to be better at
> non-stopping.
>
> WDYT ?
>
Sounds like we are applying the ARM linux limitation to a general place.
Other software single step targets may write breakpoint in atomic way,
so we don't need to stop all threads. Even in -marm mode, we don't
have to stop all threads on inserting breakpoints.
--
Yao (齐尧)
next prev parent reply other threads:[~2017-01-27 17:01 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-29 12:07 Antoine Tremblay
2016-11-29 12:07 ` [PATCH 2/2] Avoid step-over infinite loop in GDBServer Antoine Tremblay
2017-01-16 17:27 ` Antoine Tremblay
2017-01-18 16:31 ` Antoine Tremblay
2017-02-03 16:21 ` Pedro Alves
2017-02-17 3:39 ` Antoine Tremblay
2017-02-22 10:15 ` Yao Qi
2017-03-27 13:28 ` Antoine Tremblay
2016-11-29 12:12 ` [PATCH 1/2] This patch fixes GDBServer's run control for single stepping Antoine Tremblay
2017-01-16 17:28 ` Antoine Tremblay
2017-01-27 15:01 ` Yao Qi
2017-01-27 16:07 ` Antoine Tremblay
2017-01-27 17:01 ` Yao Qi [this message]
2017-01-27 18:24 ` Antoine Tremblay
2017-01-29 21:41 ` Yao Qi
2017-01-30 13:29 ` Antoine Tremblay
2017-02-03 16:13 ` Pedro Alves
2017-02-17 1:42 ` Antoine Tremblay
2017-02-17 2:05 ` Pedro Alves
2017-02-17 3:06 ` Antoine Tremblay
2017-02-17 22:19 ` Yao Qi
2017-02-18 0:19 ` Antoine Tremblay
2017-02-18 22:49 ` Yao Qi
2017-02-19 19:40 ` Antoine Tremblay
2017-02-19 20:31 ` Antoine Tremblay
2017-03-29 12:41 ` Antoine Tremblay
2017-03-29 14:11 ` Antoine Tremblay
2017-03-29 17:54 ` Antoine Tremblay
2017-03-30 16:06 ` Yao Qi
2017-03-30 18:31 ` Antoine Tremblay
2017-03-31 16:31 ` Yao Qi
2017-03-31 18:22 ` Antoine Tremblay
2017-04-03 12:41 ` Yao Qi
2017-04-03 13:18 ` Antoine Tremblay
2017-04-03 15:18 ` Yao Qi
2017-04-03 16:57 ` Antoine Tremblay
2017-02-16 22:32 ` Yao Qi
2017-02-17 2:17 ` Antoine Tremblay
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='CAH=s-PP-i3v_Fr=QeWt9BQeJzjCHtW79nGYpJ9hF-Bb=OBo89Q@mail.gmail.com' \
--to=qiyaoltc@gmail.com \
--cc=antoine.tremblay@ericsson.com \
--cc=gdb-patches@sourceware.org \
/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).