Re: internal-error: inferior* find_inferior_pid(process_stratum_target*, int): Assertion `pid != 0' failed

[Simon Marchi <simark@simark.ca>]

On 2020-02-06 1:09 p.m., Maxim Blinov wrote:
> Hi all, I have a problem running GDB in simulator mode (CGEN) for m32r and avr.
> 
> The problem in both cases seems to be to do with the following: CGEN will
> set the inferior_ptid.m_pid to 42000 (hardcoded arbitrary value). However,
> at some point, when I hit 'r' to run all, the "switch_to_no_thread()" function
> will set "inferior_ptid = null_ptid", and at some point later GDB will crash
> (see below).
> 
> Version numbers are at the bottom of email.
> 
> I can pinpoint the place at which inferior_ptid.m_pid changes from 42000 to 0,
> by running avr-gdb under my workstation-gdb, like so (the "avr-gdb" and
> "workstation-gdb" are my own prefixes, just to differentiate.):
> 
> shell-window-1$ avr-gdb hello
> (avr-gdb)
> shell-window-2$ gdb -p <the avr-gdb pid>
> (workstation-gdb)
> (workstation-gdb) watch inferior_ptid.m_pid
> (workstation-gdb) condition 1 inferior_ptid.m_pid != 42000
> (workstation-gdb) c
> (avr-gdb) target sim
> (avr-gdb) load
> (avr-gdb) info files
> Symbols from "/home/maxim/dev/ovl/avr/test-arena/hello".
> Local exec file:
>     `/home/maxim/dev/ovl/avr/test-arena/hello', file type elf32-avr.
>     Entry point: 0x0
>     0x00800100 - 0x0080010e is .data
>     0x00000000 - 0x000001b4 is .text
>     0x0080010e - 0x00800114 is .bss
> (avr-gdb) b *0x0
> (avr-gdb) r
> (workstation-gdb)
> Thread 1 "avr-gdb" hit Hardware watchpoint 2: inferior_ptid.m_pid
> 
> Old value = 42000
> New value = 0
> 0x000055f3c41229e5 in switch_to_no_thread ()
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/thread.c:1331
> 1331      inferior_ptid = null_ptid;
> (workstation-gdb) bt
> #0  0x000055f3c41229e5 in switch_to_no_thread ()
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/thread.c:1331
> #1  0x000055f3c3efae59 in switch_to_inferior_no_thread (inf=0x55f3c4d48240)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/inferior.c:623
> #2  0x000055f3c3f038c4 in commit_resume_all_targets ()
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/infrun.c:2880
> #3  0x000055f3c3f0462e in proceed (addr=0, siggnal=GDB_SIGNAL_0)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/infrun.c:3183
> #4  0x000055f3c3ef1c78 in run_command_1 (args=0x0, from_tty=1,
>     run_how=RUN_NORMAL)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/infcmd.c:678
> #5  0x000055f3c3ef1d45 in run_command (args=0x0, from_tty=1)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/infcmd.c:688
> #6  0x000055f3c3d59a24 in do_const_cfunc (c=0x55f3c4e24450, args=0x0,
>     from_tty=1)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/cli/cli-decode.c:107
> #7  0x000055f3c3d5cf43 in cmd_func (cmd=0x55f3c4e24450, args=0x0, from_tty=1)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/cli/cli-decode.c:1952
> #8  0x000055f3c412a254 in execute_command (p=0x55f3c4d0da21 "", from_tty=1)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/top.c:653
> #9  0x000055f3c3e94151 in command_handler (command=0x55f3c4d0da20 "")
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/event-top.c:587
> #10 0x000055f3c3e945cb in command_line_handler (rl=...)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/event-top.c:772
> #11 0x000055f3c3e938c5 in gdb_rl_callback_handler (rl=0x55f3c4edca80 "r")
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/event-top.c:218
> #12 0x000055f3c41f9d39 in rl_callback_read_char ()
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./readline/readline/callback.c:281
> #13 0x000055f3c3e936ed in gdb_rl_callback_read_char_wrapper_noexcept ()
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/event-top.c:176
> #14 0x000055f3c3e93797 in gdb_rl_callback_read_char_wrapper (
>     client_data=0x55f3c4d0d770)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/event-top.c:193
> #15 0x000055f3c3e93fe3 in stdin_event_handler (error=0,
>     client_data=0x55f3c4d0d770)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/event-top.c:515
> #16 0x000055f3c3e91bfe in handle_file_event (file_ptr=0x55f3c4ec93c0,
>     ready_mask=1)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/event-loop.c:731
> #17 0x000055f3c3e921c7 in gdb_wait_for_event (block=1)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/event-loop.c:857
> #18 0x000055f3c3e90fcd in gdb_do_one_event ()
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/event-loop.c:346
> #19 0x000055f3c3e90ff7 in start_event_loop ()
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/event-loop.c:370
> #20 0x000055f3c3f507b0 in captured_command_loop ()
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/main.c:360
> #21 0x000055f3c3f520ad in captured_main (data=0x7fff597e8340)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/main.c:1203
> #22 0x000055f3c3f52113 in gdb_main (args=0x7fff597e8340)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/main.c:1218
> #23 0x000055f3c3c71cc3 in main (argc=2, argv=0x7fff597e8448)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/gdb.c:32
> (workstation-gdb) c
> 
> ...
> At this point, I hit the hardware watchpoint 2 more times. I'm not sure if thats
> significant, but its just the same "changed from 42000 to 0".
> ...
> 
> (avr-gdb)
> Starting program: /home/maxim/dev/ovl/avr/test-arena/hello
> /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/inferior.c:279:
> internal-error: inferior* find_inferior_pid(process_stratum_target*,
> int): Assertion `pid != 0' failed.
> A problem internal to GDB has been detected,
> further debugging may prove unreliable.
> Quit this debugging session? (y or n)
> 
> 
> And thats that. I originally did this for m32r, but when that failed, I went
> to avr but has exactly the same problem.
> 
> 
> Here is the coredump backtrace for avr-gdb:
> 
> ```
> #0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
> #1  0x00007f404663d801 in __GI_abort () at abort.c:79
> #2  0x000055cb48885d69 in dump_core ()
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/utils.c:203
> #3  0x000055cb4888630e in internal_vproblem(internal_problem *, const
> char *, int, const char *, typedef __va_list_tag __va_list_tag *) (
>     problem=0x55cb48f27660 <internal_error_problem>,
>     file=0x55cb48a85738 "/home/maxim/dev/ovl/avr/binutils-gdb/./gdb/inferior.c",
>     line=279, fmt=0x55cb48a856ab "%s: Assertion `%s' failed.",
> ap=0x7fff97d46a70)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/utils.c:413
> #4  0x000055cb488863f3 in internal_verror (
>     file=0x55cb48a85738 "/home/maxim/dev/ovl/avr/binutils-gdb/./gdb/inferior.c",
>     line=279, fmt=0x55cb48a856ab "%s: Assertion `%s' failed.",
> ap=0x7fff97d46a70)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/utils.c:438
> #5  0x000055cb489cf758 in internal_error (
>     file=0x55cb48a85738 "/home/maxim/dev/ovl/avr/binutils-gdb/./gdb/inferior.c",
>     line=279, fmt=0x55cb48a856ab "%s: Assertion `%s' failed.")
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdbsupport/errors.c:55
> #6  0x000055cb4860b7c3 in find_inferior_pid (targ=0x55cb48f26de0
> <gdbsim_ops>, pid=0)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/inferior.c:279
> #7  0x000055cb4860b88a in find_inferior_ptid (targ=0x55cb48f26de0 <gdbsim_ops>,
>     ptid=...) at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/inferior.c:293
> #8  0x000055cb48831d29 in find_thread_ptid (targ=0x55cb48f26de0
> <gdbsim_ops>, ptid=...)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/thread.c:527
> #9  0x000055cb4861b629 in handle_inferior_event (ecs=0x7fff97d46ec0)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/infrun.c:5062
> #10 0x000055cb48618ab9 in fetch_inferior_event (client_data=0x0)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/infrun.c:4002
> #11 0x000055cb485fcb43 in inferior_event_handler (event_type=INF_REG_EVENT,
>     client_data=0x0) at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/inf-loop.c:43
> #12 0x000055cb48624b9c in infrun_async_inferior_event_handler (data=0x0)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/infrun.c:9317
> #13 0x000055cb485a468e in check_async_event_handlers ()
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/event-loop.c:1062
> #14 0x000055cb485a2f5f in gdb_do_one_event ()
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/event-loop.c:325
> #15 0x000055cb485a2ff7 in start_event_loop ()
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/event-loop.c:370
> #16 0x000055cb486627b0 in captured_command_loop ()
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/main.c:360
> #17 0x000055cb486640ad in captured_main (data=0x7fff97d470e0)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/main.c:1203
> #18 0x000055cb48664113 in gdb_main (args=0x7fff97d470e0)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/main.c:1218
> #19 0x000055cb48383cc3 in main (argc=2, argv=0x7fff97d471e8)
>     at /home/maxim/dev/ovl/avr/binutils-gdb/./gdb/gdb.c:32
> ```
> 
> And here is the coredump backtrace for m32r-unknown-elf-gdb:
> 
> ```
> #0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
> #1  0x00007f5562123801 in __GI_abort () at abort.c:79
> #2  0x00005599a200c3a7 in dump_core ()
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/utils.c:203
> #3  0x00005599a200c94c in internal_vproblem(internal_problem *, const
> char *, int, const char *, typedef __va_list_tag __va_list_tag *) (
>     problem=0x5599a2744740 <internal_error_problem>,
>     file=0x5599a2280758
> "/home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/inferior.c",
>     line=279, fmt=0x5599a22806cb "%s: Assertion `%s' failed.",
> ap=0x7ffc2d752ff0)
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/utils.c:413
> #4  0x00005599a200ca31 in internal_verror (
>     file=0x5599a2280758
> "/home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/inferior.c",
>     line=279, fmt=0x5599a22806cb "%s: Assertion `%s' failed.",
> ap=0x7ffc2d752ff0)
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/utils.c:438
> #5  0x00005599a21bf5a0 in internal_error (
>     file=0x5599a2280758
> "/home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/inferior.c",
>     line=279, fmt=0x5599a22806cb "%s: Assertion `%s' failed.")
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdbsupport/errors.c:55
> #6  0x00005599a1d906a7 in find_inferior_pid (targ=0x5599a2743ec0
> <gdbsim_ops>, pid=0)
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/inferior.c:279
> #7  0x00005599a1d9076e in find_inferior_ptid (targ=0x5599a2743ec0 <gdbsim_ops>,
>     ptid=...) at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/inferior.c:293
> #8  0x00005599a1fb8367 in find_thread_ptid (targ=0x5599a2743ec0
> <gdbsim_ops>, ptid=...)
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/thread.c:527
> #9  0x00005599a1da050d in handle_inferior_event (ecs=0x7ffc2d753440)
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/infrun.c:5062
> #10 0x00005599a1d9d99d in fetch_inferior_event (client_data=0x0)
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/infrun.c:4002
> #11 0x00005599a1d81a27 in inferior_event_handler (event_type=INF_REG_EVENT,
>     client_data=0x0) at
> /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/inf-loop.c:43
> #12 0x00005599a1da9a80 in infrun_async_inferior_event_handler (data=0x0)
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/infrun.c:9317
> #13 0x00005599a1d29572 in check_async_event_handlers ()
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/event-loop.c:1062
> #14 0x00005599a1d27e43 in gdb_do_one_event ()
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/event-loop.c:325
> #15 0x00005599a1d27edb in start_event_loop ()
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/event-loop.c:370
> #16 0x00005599a1de8dee in captured_command_loop ()
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/main.c:360
> #17 0x00005599a1dea6eb in captured_main (data=0x7ffc2d753660)
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/main.c:1203
> #18 0x00005599a1dea751 in gdb_main (args=0x7ffc2d753660)
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/main.c:1218
> #19 0x00005599a1b0b413 in main (argc=2, argv=0x7ffc2d753768)
>     at /home/maxim/dev/ovl/m32r/binutils-gdb/./gdb/gdb.c:32
> ```
> 
> I saw this discussion that seemed to have a very similar problem, here:
> https://sourceware.org/ml/gdb-patches/2019-10/msg00512.html
> 
> The patch doesn't apply anymore, but even when I did try adding an equivalent
> statement, it still didn't work (I only tried with AVR though).
> 
> Version numbers:
> 
> maxim@fujitsu:~/dev/ovl/avr/test-arena$ avr-gdb --version
> GNU gdb (GDB) 10.0.50.20200201-git
> Copyright (C) 2020 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.
> maxim@fujitsu:~/dev/ovl/avr/test-arena$ avr-as --version
> GNU assembler (GNU Binutils) 2.34
> Copyright (C) 2020 Free Software Foundation, Inc.
> This program is free software; you may redistribute it under the terms of
> the GNU General Public Licence version 3 or later.
> This program has absolutely no warranty.
> This assembler was configured for a target of `avr'.
> 
> Maxim
> 

Hi Maxim,

I didn't read your backtraces in details, but this looks very much like what
was fixed by this patch (present in master):

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=cf1d9e092f871df3b34a58cfcde915c689ac9067

Can you check if you have it?

Simon