[Pkg-rust-maintainers] Bug#973414: libmozjs-78-0: invalid opcodes in libmozjs when launching GDM3

[Martin-Éric Racine]

to 10. jouluk. 2020 klo 19.47 Simon McVittie (smcv at debian.org) kirjoitti:
>
> On Thu, 10 Dec 2020 at 18:29:39 +0200, Martin-Éric Racine wrote:
> > Btw, when it comes to libmozjs, is there any attachment you'd need?
> > gdb backtrace, etc.?
>
> A backtrace is always useful, and it would also be useful to know which
> opcode not supported by your CPU it's trying to execute.

$ sudo coredumpctl debug 855 --output /tmp/coredump_gnome-shell
           PID: 855 (gnome-shell)
           UID: 101 (Debian-gdm)
           GID: 122 (Debian-gdm)
        Signal: 4 (ILL)
     Timestamp: Thu 2020-12-10 18:38:09 EET (1h 15min ago)
  Command Line: /usr/bin/gnome-shell
    Executable: /usr/bin/gnome-shell
 Control Group: /user.slice/user-101.slice/session-c2.scope
          Unit: session-c2.scope
         Slice: user-101.slice
       Session: c2
     Owner UID: 101 (Debian-gdm)
       Boot ID: b115ec37ecca4f75acd8d60bc6a44403
    Machine ID: 1063a9d1fb9df6e371ea9f94491345ed
      Hostname: geode
       Storage:
/var/lib/systemd/coredump/core.gnome-shell.101.b115ec37ecca4f75acd8d60bc6a44403.855.1607618289000000.zst
       Message: Process 855 (gnome-shell) of user 101 dumped core.

                Stack trace of thread 861:
                #0  0x00000000b5500d08
_ZN17compiler_builtins3int4udiv12__udivmoddi417h8768e341ea5a27afE
(libmozjs-78.so.0 + 0xa01d08)

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Reading symbols from /usr/bin/gnome-shell...
(No debugging symbols found in /usr/bin/gnome-shell)
[New LWP 861]
[New LWP 855]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/i386-linux-gnu/libthread_db.so.1".

warning: Can't read data for section '.debug_info' in file
'/usr/lib/debug/.build-id/8e/1bdec525caa9d999e8d03f4e90d5e350bddf4f.debug'
Core was generated by `/usr/bin/gnome-shell'.
Program terminated with signal SIGILL, Illegal instruction.
#0  0xb5500d08 in compiler_builtins::int::udiv::__udivmoddi4 () from
/usr/lib/i386-linux-gnu/libmozjs-78.so.0
[Current thread is 1 (Thread 0xb15c9b40 (LWP 861))]
(gdb) bt full
#0  0xb5500d08 in compiler_builtins::int::udiv::__udivmoddi4 () from
/usr/lib/i386-linux-gnu/libmozjs-78.so.0
No symbol table info available.
(gdb) c
The program is not being run.
(gdb)

> I'm sure you know more than I do about the finer points of the x86
> instruction set and how opcodes map to CPU flags and architecture
> extensions.

Sadly not. I only remember that the Geode LX is 1 instruction short of
a standard 686.

Martin-Éric