RE: [PATCH] gdbserver: Install single-step breakpoint for a pending thread whose last_resume_kind is resume_step

["Yan, Zhiyong" <Zhiyong.Yan@windriver.com>]

Hi Kevin,
     Thanks for your effort.

Best Regards.
Zhiyong

-----Original Message-----
From: Kevin Buettner <kevinb@redhat.com> 
Sent: Wednesday, July 26, 2023 11:59 AM
To: Yan, Zhiyong <Zhiyong.Yan@windriver.com>
Cc: gdb-patches@sourceware.org; luis.machado@arm.com; tom@tromey.com
Subject: Re: [PATCH] gdbserver: Install single-step breakpoint for a pending thread whose last_resume_kind is resume_step

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,

I've finally been able to reproduce the bug on a Raspberry Pi. On a different SD card, I installed 32-bit Ubunutu server 20.04.5 LTS.  It seems to have both a 32-bit (arm) kernel + 32-bit userland.  I.e...

kev@rpi4-3:~/Downloads/bz30387$ uname -m armv7l kev@rpi4-3:~/Downloads/bz30387$ file ./osm
./osm: ELF 32-bit LSB shared object, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-armhf.so.3, BuildID[sha1]=81e7e2b5dfba0fe35f1f1a6af2ee558efbdafa7f, for GNU/Linux 3.2.0, with debug_info, not stripped

(Compare the above output to that your reported on your Pi; on your Pi, uname -m reported aarch64 and the 'file' command showed 64-bit
aarch64 binaries.)

The internal error appears to be the same as that described in your bug report as well as on the gdb-patches list:

/mesquite2/sourceware-git/rpi-arm-master/bld/../../worktree-master/gdbserver/linux-low.cc:2448: A problem internal to GDBserver has been detected.
maybe_hw_step: Assertion `has_single_step_breakpoints (thread)' failed.

Now that I've reproduced it, I want to retest gdb.threads/*.exp to see if any of those tests show the same failure.  If not, I'll try to adapt your test case into one suitable for the gdb test suite.

I have an alternate patch in mind, which I'll try out too.  If it works out, I'll ask you to test it on your hardware...

Kevin