not possible to retrace ppc64el crashes

[Brian Murray]

I was trying to retrace a ppc64el crash I found and ran into the following issue:

Calling gdb command: gdb-multiarch --ex 'set architecture powerpc:common' --ex 'set gnutarget elf32-powerpc' --ex 'set debug-file-directory /tmp/apport_sandbox_Y6fXCx/usr/lib/debug' --ex 'set solib-absolute-prefix /tmp/apport_sandbox_Y6fXCx' --ex 'file "/tmp/apport_sandbox_Y6fXCx//usr/bin/xfce4-panel"' --ex 'core-file /tmp/apport_core_N0Vrmm'
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The target architecture is assumed to be powerpc:common
Architecture of file not recognized.
[New LWP 44625]
warning: Selected architecture powerpc:common is not compatible with reported target architecture powerpc:common64
/build/buildd/gdb-7.7.1/gdb/gdbarch.c:3217: internal-error: gdbarch_elf_make_msymbol_special: Assertion `gdbarch != NULL' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.

[Brian Murray (brian-murray)]

This is because of the following lines in report.py:

            # check for foreign architecture
            arch = self.get('Uname', 'none').split()[-1]
            if 'arm' in arch:
                command += ['--ex', 'set architecture arm', '--ex', 'set gnutarget elf32-littlearm']
            elif 'ppc' in arch:
                command += ['--ex', 'set architecture powerpc:common', '--ex', 'set gnutarget elf32-powerpc']
            # note, i386 vs. x86_64 is auto-detected just fine

I wonder if these are really needed as I retraced some arm64 crashes, uname with aarch64, and they retraced the same as when I added the following to report.py:

            if 'aarch64' in arch:
                command += ['--ex', 'set architecture aarch64', '--ex', 'set gnutarget elf64-littleaarch64']

[Brian Murray (brian-murray)]

I've removed the ppc check and ppc64el cores were detected and retraced fine.

[Brian Murray (brian-murray)]

I removed all the checks and armv7l crashes were retraced fine too.

[Brian Murray (brian-murray)]

If you don't want to remove the arch checks this works:

           if 'aarch64' in arch:
               command += ['--ex', 'set architecture aarch64', '--ex', 'set gnutarget elf64-littleaarch64']
           elif 'ppc64le' in arch:
               command += ['--ex', 'set architecture powerpc:common64', '--ex', 'set gnutarget elf64-powerpcle']

[Brian Murray (brian-murray)]

It's probably worth noting I was testing with the following version of gdb from Trusty:

 *** 7.7.1-0ubuntu5~14.04.2 0
        500 http://prodstack-zone-1.clouds.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages

[Brian Murray (brian-murray)]

I also tried my special gdb backport and that works well too.

ubuntu@juju-stg-ue-error-tracker-machine-10:/tmp$ apt-cache policy gdb
gdb:
  Installed: 7.10-1ubuntu3~14.04.1
  Candidate: 7.10-1ubuntu3~14.04.1
  Version table:
 *** 7.10-1ubuntu3~14.04.1 0
        500 http://ppa.launchpad.net/daisy-pluckers/daisy-seeds/ubuntu/ trusty/main amd64 Packages

[Martin Pitt (pitti)]

Brian, thanks for testing those. Back when I wrote this I had the impression that gdb sometimes got confused and needed those additional "set architecture" commands. But if current versions (≥ trusty) don't need it, so much the better!

[Martin Pitt (pitti)]

Fixed in http://bazaar.launchpad.net/~apport-hackers/apport/trunk/revision/3083

[Launchpad Janitor (janitor)]

This bug was fixed in the package apport - 2.20.2-0ubuntu1

---------------
apport (2.20.2-0ubuntu1) yakkety; urgency=medium

  [ Brian Murray ]
  * data/general-hooks/ubuntu.py: tag bug reports 'apport-hook-error' if they
    have an attachment from an apport hook which crashed.

  [ Martin Pitt ]
  * New upstream release. Changes since our previous snapshot:
    - Don't ignore OSError in Report.add_gdb_info(), as we do want to fail with an
      useful error message if gdb cannot be called in apport-retrace. Move the
      catching to the UI as not having gdb installed is still fine for reporting
      clients. (LP: #1579949)
    - Show gdb error messages in Report.add_gdb_info() OSError exception when gdb
      fails. (LP: #1579897)
    - hookutils, attach_root_command_outputs(): Return str again, like before
      2.15.2. (LP: #1370259)
    - Stop issuing "set architecture" gdb commands on ARM and Power; these only
      applied to 32 bit platforms and are apparently not needed any more with
      recent gdb versions. (LP: #1585702)
    - Disable report.test_add_gdb_info_abort_libnih test case for now, as libnih
      is broken under current Ubuntu (LP: #1580601)

 -- Martin Pitt <email address hidden> Sun, 19 Jun 2016 22:17:35 +0200