[PATCH] [patch] gdbserver assert error on arm platform

[Kevin Buettner]

Hi Zhiyong,

If possible, it'd be nice if you could write a test case which would
run when a developer does "make check" (with suitable RUNTESTFLAGS and
--target_board settings).  I'd guess that you'd put your new .exp
file and source file into gdb/testsuite/gdb.server.  If you look around
in that directory (and perhaps in some of the other testing directories
too) you might find something similar upon which to base your new
test.

I know from experience that it's sometimes a hassle to write these
test cases, but they're extremely useful in the long term because
regression testing will show if/when the bug (or some other) crops up
again.

Here are a couple of links which might help you to rework your existing
test into a test case for GDB:

Testing GDB:
https://sourceware.org/gdb/wiki/TestingGDB

GDB Testcase Cookbook:
https://sourceware.org/gdb/wiki/GDBTestcaseCookbook

Please also note that I commented on some formatting nits.  Please
address those too.  If you're wondering about GDB's coding conventions,
please see:

https://sourceware.org/gdb/wiki/ContributionChecklist#Properly_Formatted_Changes

Kevin

On Tue, 20 Jun 2023 08:08:52 +0000
"Yan, Zhiyong" <Zhiyong.Yan@windriver.com> wrote:

> Hi Bruno,
>      The test case is attached into https://sourceware.org/bugzilla/show_bug.cgi?id=30387. Please look for "Luis Machado 2023-05-02 14:17:40 UTC" in Bugzilla comments, you can see Luis already produced this issue.
>      I copy Produce step below, test app and gdb script can be found in the attachment.
> 
> Produce step (This issue can only be produced on arm platform):
> 
> (1) tar xvf gdbserver-test-app.tar on a host which can do arm-cross compile.
> (2) In osm.service, modify ExecStart path according to your running environment.
> (3) make
> (4) Please refer to "make install", install osm systemd service on target board.
> 
> [On target board]
> systemctl daemon-reload
> systemctl start osm
> gdbserver --debug --debug-format=all --remote-debug --event-loop-debug --once --attach :1234 $(pgrep osm)
> 
> [On pc host]
> your-arm-gdb ./osm(this is test app build out as above)  -x ~/gdbx2
> 
> gdbx2 can be found in the attachment, please modify target-remote pointing to your  target board's gdbserver in gdbx2.
> 
> When gdb executes gdbx2, gdbserver will assert on target board.
>      
> 
> -----Original Message-----
> From: Bruno Larsen <blarsen@redhat.com> 
> Sent: Tuesday, June 20, 2023 3:36 PM
> To: Yan, Zhiyong <Zhiyong.Yan@windriver.com>; gdb-patches@sourceware.org
> Cc: tom@tromey.com
> Subject: Re: [PATCH] [patch] gdbserver assert error on arm platform
> 
> CAUTION: This email comes from a non Wind River email account!
> Do not click links or open attachments unless you recognize the sender and know the content is safe.
> 
> Hi Zhiyong,
> 
> Kevin has posted a review back in may 11th:
> https://inbox.sourceware.org/gdb-patches/20230511140407.0a0977fb@f37-zws-nv/
> 
> --
> Cheers,
> Bruno
> 
> On 19/06/2023 03:50, Yan, Zhiyong wrote:
> > Hi,
> >      Did this patch get a chance of review ?
> >
> > Thanks!
> > Zhiyong
> >
> >
> >
> > -----Original Message-----
> > From: zhiyong.yan@windriver.com <zhiyong.yan@windriver.com>
> > Sent: Thursday, May 11, 2023 2:20 PM
> > To: gdb-patches@sourceware.org
> > Cc: tom@tromey.com; Yan, Zhiyong <Zhiyong.Yan@windriver.com>
> > Subject: [PATCH] [patch] gdbserver assert error on arm platform
> >
> > From: Zhiyong Yan <zhiyong.yan@windriver.com>
> >
> > Bugzilla 30387 has given the steps of producing this issue on arm platform.
> > Gdb should not assume pending threads always generate ___a non-gdbserver trap event___, a ___Signal 17___ event could happen.
> > Now that resume_stopped_resumed_lwps() -> may_hw_step() assumes that the break point must already exist, resume_one_thread() should ensure the software breaking point is installed although the thread is pending.
> >
> > LINK: https://sourceware.org/bugzilla/show_bug.cgi?id=30387
> >
> > Signed-off-by: Zhiyong Yan zhiyong.yan@windriver.com
> > ---
> >   gdbserver/linux-low.cc | 12 ++++++++++--
> >   1 file changed, 10 insertions(+), 2 deletions(-)
> >
> > diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc index e6a39202a98..543daf66376 100644
> > --- a/gdbserver/linux-low.cc
> > +++ b/gdbserver/linux-low.cc
> > @@ -4670,8 +4670,16 @@ linux_process_target::resume_one_thread (thread_info *thread,
> >
> >         proceed_one_lwp (thread, NULL);
> >       }
> > -  else
> > -    threads_debug_printf ("leaving LWP %ld stopped", lwpid_of (thread));
> > +  else{
> > +     threads_debug_printf ("leaving LWP %ld stopped", lwpid_of (thread));
> > +     if(thread->last_resume_kind == resume_step){
> > +         /*
> > +         * If resume_step is required by GDB, install single-step breakpoint.
> > +         */
> > +         if (supports_software_single_step())
> > +            install_software_single_step_breakpoints (lwp);
> > +     }
> > +  }
> >
> >     thread->last_status.set_ignore ();
> >     lwp->resume = NULL;
> > --
> > 2.25.1
> >  
>