[Bug gdb/28874] New: arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[Bug gdb/28874] New: arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[git at jbrengineering dot co.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

            Bug ID: 28874
           Summary: arm-none-eabi: internal-error: thread_info*
                    inferior_thread(): Assertion `current_thread_ !=
                    nullptr' failed
           Product: gdb
           Version: 11.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: git at jbrengineering dot co.uk
  Target Milestone: ---

Created attachment 13963
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13963&action=edit
core dump

Following from the fix (https://sourceware.org/bugzilla/show_bug.cgi?id=28405)
for remote targets found when using a Black Magic Probe, 11.2 now has a new
error when attempting to attach:

thread.c:72: internal-error: thread_info* inferior_thread(): Assertion
`current_thread_ != nullptr' failed.

Core dump attached. I have re-confirmed that the patch in the original problem
ticket works on the 11.1 branch (to make sure I wasn't going mad!) so something
in the 11.2 merge has caused this?

Happy to help with further info.

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[git at jbrengineering dot co.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

John Whittington <git at jbrengineering dot co.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
               Host|                            |arch
             Target|                            |arm-none-eabi

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[git at jbrengineering dot co.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

John Whittington <git at jbrengineering dot co.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                URL|                            |https://github.com/blackmag
                   |                            |ic-debug/blackmagic/issues/
                   |                            |929

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[me at ruff dot mobi]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

Ruslan N. Marchenko <me at ruff dot mobi> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |me at ruff dot mobi

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
                 CC|                            |tromey at sourceware dot org
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2022-03-06

--- Comment #1 from Tom Tromey <tromey at sourceware dot org> ---
Hi.  Thanks for the report.
A gdb core file isn't super useful to us, because it is specific to
your particular build of gdb.
A stack trace might help more.

If the bug can reliably be reproduced with some small executable
and a connection to a remote, then another good option is to
attach the executable and use "set remotelogfile" to capture
the remote protocol trace -- this can often be replayed in gdb
to reproduce the bug.

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[me at ruff dot mobi]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

--- Comment #2 from Ruslan N. Marchenko <me at ruff dot mobi> ---
In my case executable is irrelevant, you can simply have none at all.
Just need a remote debugger (I use BMP) and then as simple as 
$ arm-none-eabi-gdb
GNU gdb (GDB) 11.2
Copyright (C) 2022 Free Software Foundation, Inc.
...
For help, type "help".
Type "apropos word" to search for commands related to "word".
(gdb) tar ext /dev/ttyACM0
Remote debugging using /dev/ttyACM0
(gdb) mon s
Target voltage: 3.29V
Available Targets:
No. Att Driver
 1      STM32L47x M4
(gdb) set debug remote on
(gdb) attach 1
Attaching to Remote target
[remote] Sending packet: $vAttach;1#37
[remote] Received Ack
[remote] Packet received: T05
[remote] packet_ok: Packet vAttach (attach) is supported
[remote] Sending packet: $qC#b4
[remote] Received Ack
[remote] Packet received:
../../gdb/thread.c:72: internal-error: thread_info* inferior_thread():
Assertion `current_thread_ != nullptr' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[me at ruff dot mobi]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

--- Comment #3 from Ruslan N. Marchenko <me at ruff dot mobi> ---
P.S. I'm running GDB v8.2.1 in a container as of now for debug, that works ok

$ podman run -i --device=/dev/ttyACM0 -v .:/home/user/cwd
--group-add=keep-groups debian/buster:gdb
GNU gdb (Debian 8.2.1-2+b3) 8.2.1
Copyright (C) 2018 Free Software Foundation, Inc.
...
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from bin/firmware.elf...done.
Remote debugging using /dev/ttyACM0
(gdb) attach 1
Attaching to program: /home/user/cwd/bin/firmware.elf, Remote target
0x080001ec in ?? ()
(gdb)

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

--- Comment #4 from Tom Tromey <tromey at sourceware dot org> ---
> (gdb) mon s
> Target voltage: 3.29V
> Available Targets:
> No. Att Driver
>  1      STM32L47x M4

Is this special hardware?  Just wondering how I'd reproduce it.

> (gdb) set debug remote on

Do "set remotelogfile /tmp/mumble" before the "target" command.
Then, after gdb crashes, attach that log to the bug.
That should be enough, I suspect, to reproduce in gdb without
any special setup.
Thanks.

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[me at ruff dot mobi]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

--- Comment #5 from Ruslan N. Marchenko <me at ruff dot mobi> ---
Created attachment 14009
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14009&action=edit
remote log

Ah, before, I forgot that part. Here it is.

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[me at ruff dot mobi]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

--- Comment #6 from Ruslan N. Marchenko <me at ruff dot mobi> ---
And it was on Nucleo64 dev board but this is irrelevant, it's about remote
protocol, not remote target. "mon s" just to demonstrate that remote target is
alive.

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[git at jbrengineering dot co.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

--- Comment #7 from John Whittington <git at jbrengineering dot co.uk> ---
Created attachment 14010
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14010&action=edit
stm32f4 remote log

In case it helps move this forwards, here is a remote log of me using a Black
Magic Probe attempting to attach to a STM32F4.

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[git at jbrengineering dot co.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

--- Comment #8 from John Whittington <git at jbrengineering dot co.uk> ---
Created attachment 14011
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14011&action=edit
remote log patched working

Same commands but with switch_to_thread (thread); attaches successfully and
allows control of target.

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[git at jbrengineering dot co.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

--- Comment #9 from John Whittington <git at jbrengineering dot co.uk> ---
Created attachment 14012
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14012&action=edit
patched remote add thread

I had a bit of time and comparing diff of 11.1 with patch in original ticket,
the combination of `add_thread_silent` into `remote_add_thread` for bare metal
targets incorrectly orders the `switch_to_thread` call and the setting of the
thread states `set_thread..`.

I'll be honest I don't fully understand the thread methods here, but this is
what appears to be the case and fixes the issue. I assume the
`switch_to_thread` makes the phony thread real?

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[klen_s at mail dot ru]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

Chernov Sergey aka Klen <klen_s at mail dot ru> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |klen_s at mail dot ru

--- Comment #10 from Chernov Sergey aka Klen <klen_s at mail dot ru> ---
yyyeeess!!!!  it's work fine!
finally, you can assemble the otadchik from the trunk and test everything new!
I am about twice a week rebuilding all the tools and libraries from the trunk
and studying the errors of new features, sometimes I can help fix them. But
with this error, I could not do anything, it appeared in the trunk in October.
John Whittington, you are the best :), thank you so much!
maybe this is a crutch and something will break if the processor has two cores
or there will be another target, but here and now it works!


klen@klen-station:/klen/home/arm-kgp-eabi_@_x86_64-kgp-linux-gnu_znver3_avx2$
arm-kgp-eabi-gdb
GNU gdb
(Klen's_GNU_package_(KGP)_for_target::arm-kgp-eabi<rmprofile/lto>_host::x86_64-kgp-linux-gnu<<OXALIS>>)
12.0.50.20220315-git
Copyright (C) 2022 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "--host=x86_64-kgp-linux-gnu --target=arm-kgp-eabi".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<klen_s@mail.ru>.
Find the GDB manual and other documentation resources online at:
    <http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word".
(gdb) tar ext /dev/kgp/bmp
Remote debugging using /dev/kgp/bmp
(gdb) mon s
Target voltage: 0.0V
Available Targets:
No. Att Driver
 1      STM32H7 M7
(gdb) att 1
Attaching to Remote target
0x0800bb2e in ?? ()

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[git at jbrengineering dot co.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

John Whittington <git at jbrengineering dot co.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #14012|0                           |1
        is obsolete|                            |

--- Comment #11 from John Whittington <git at jbrengineering dot co.uk> ---
Created attachment 14022
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14022&action=edit
patched remote add thread

Glad to hear the fix works for you too and the kind words :).

How do we get this patch into the next release? I've updated diff with
ChangeLog updated and matched formatting. Whilst it is a bit of the hack for
the silent_p flag, looking at the 11.1 diff, that flag was added solely for
non-threaded targets like the BMP. Should it be sent to mailing list?

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[klen_s at mail dot ru]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

--- Comment #12 from Chernov Sergey aka Klen <klen_s at mail dot ru> ---
Despite the fact that I am also a little in kurma how it all works, I can not
say anything definitively.
Due to the fact that microcontrollers sometimes began to have more than one
core, a situation arose that the infrastructure for remote debugging should be
fundamentally expanded ( cpu cores, multithreading etc ), probably not done
with just skewers and patches. Judging by the code 11.1 - it works correctly
but "in the old way". In 11.2, they started trying to fix it and broke
everything :) It will probably take a lot of work to make it elegant and
reliable again on different targets
I tried your changes on trunk code - it also fixes the problem... but
unfortunately gdb now crashes when communicating via MI protocol with eclipse
IDE. in the console everything is fine and correctly debugged.

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW

--- Comment #13 from Tom Tromey <tromey at sourceware dot org> ---
> How do we get this patch into the next release? I've updated diff with
> ChangeLog updated and matched formatting. Whilst it is a bit of the hack for
> the silent_p flag, looking at the 11.1 diff, that flag was added solely for
> non-threaded targets like the BMP. Should it be sent to mailing list?

ChangeLogs are gone now, fwiw.

Anyway, gdb patches are usually reviewed on the gdb-patches list.
See https://sourceware.org/gdb/wiki/ContributionChecklist

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[mikaela.szekely at qyriad dot me]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

Mikaela Szekely <mikaela.szekely at qyriad dot me> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mikaela.szekely at qyriad dot me

--- Comment #14 from Mikaela Szekely <mikaela.szekely at qyriad dot me> ---
Created attachment 14040
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14040&action=edit
added has_inferior_thread() and checks it in remote_add_thread()

> Whilst it is a bit of the hack for
> the silent_p flag, looking at the 11.1 diff, that flag was added solely for
> non-threaded targets like the BMP.

I don't fully understand the thread methods here either, but
`extended_remote_target::attach()` calls `switch_to_inferior_no_thread()`
before calling `remote_add_thread()` for any target where
`target_is_non_stop_p() == false`, with no `switch_to_thread()` in-between, so
I think this bug might affect more than just non-threaded targets?

I would be interested to know if any other targets are experiencing this bug,
but either way if you'd like a less hacky and possibly more general-case
solution for this, then that might just be to check in `remote_add_thread()` if
there is a current thread or not, and switch if not, as in this patch? This
patch does create more diff-noise, though; I'm not sure which is preferable for
gdb.

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[jj at stusta dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

Jonas Jelten <jj at stusta dot net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jj at stusta dot net

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[git at jbrengineering dot co.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

--- Comment #15 from John Whittington <git at jbrengineering dot co.uk> ---
Do you ever get any feedback Mikaela (patch works for me)? If it doesn't break
any tests it would be good to try and get this merged.

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[mikaela.szekely at qyriad dot me]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

--- Comment #16 from Mikaela Szekely <mikaela.szekely at qyriad dot me> ---
I have not. I have even bumped the patch thread asking if there are any
questions about the patch
(https://sourceware.org/pipermail/gdb-patches/2022-June/190342.html), but it
has not received any responses.

If there are any maintainers watching this bug I'd love to know if there's
anything I can do to help get this patch merged.

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[git at jbrengineering dot co.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

--- Comment #17 from John Whittington <git at jbrengineering dot co.uk> ---
The Black Magic Probe firmware has now been updated to support fake threads
rather than waiting/hoping for a fix in GDB for this:
https://github.com/blackmagic-debug/blackmagic/pull/1125

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[luis.machado at arm dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

Luis Machado <luis.machado at arm dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |luis.machado at arm dot com
             Status|NEW                         |WAITING

--- Comment #18 from Luis Machado <luis.machado at arm dot com> ---
Is this an issue with using thread/process 0 as identifier?

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[Bug gdb/28874] arm-none-eabi: internal-error: thread_info* inferior_thread(): Assertion `current_thread_ != nullptr' failed

[gdbsourceware.3k5z5 at passmail dot net]

https://sourceware.org/bugzilla/show_bug.cgi?id=28874

fidgetingbits <gdbsourceware.3k5z5 at passmail dot net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gdbsourceware.3k5z5@passmai
                   |                            |l.net

--- Comment #19 from fidgetingbits <gdbsourceware.3k5z5 at passmail dot net> ---
I run into this same issue on the latest version of gdb (13.2 at the time of
writing) and gdbserver when debugging various remote 32-bit ARM targets,
specifically when using
pwndbg loaded (sets up various event hooks).

Also worth noting that after gdb crashes, if you restart gdb and re-attach a
second time without restarting the target process, the attach works correctly.
My solution has always been to just automatically restart gdb on crash and
re-attach from a shell script.

I've confirmed that using the patch provided by John Whittington addresses the
problem.

Would be nice to get this fixed as pwndbg users wishing to remotely debug an
ARM target will run into this issue.

Happy to provide any debug information needed.

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