[Bug 2075204] Re: gdb on s390x chokes on divide-by-zero from chaos-marmosets

[Frank Heimes]

Thanks Andreas for the update and bringing this upstream.
I'll reference the upstream bug with the LP bug meta data to stay informed ...

** Changed in: ubuntu-z-systems
       Status: New => Triaged

** Changed in: gdb (Ubuntu)
       Status: New => Confirmed

** Changed in: ubuntu-z-systems
       Status: Triaged => Confirmed

** Also affects: gdb via
   https://sourceware.org/bugzilla/show_bug.cgi?id=32278
   Importance: Unknown
       Status: Unknown

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Title:
  gdb on s390x chokes on divide-by-zero from chaos-marmosets

Status in gdb:
  Unknown
Status in Ubuntu on IBM z Systems:
  Confirmed
Status in gdb package in Ubuntu:
  Confirmed

Bug description:
  To help in the development of apport we're using the chaos-marmosets
  set of binaries, which triggers various crashes. In particular, we're
  using /usr/bin/divide-by-zero which does as its name indicates, which
  naturally triggers a native crash.

  However, GDB fails on s390x. Note that for the following I have the
  debugging symbols from ddebs.ubuntu.com installed:

  ubuntu at glibc-proposed:/tmp$ gdb /usr/bin/divide-by-zero
  [snip]
  Reading symbols from /usr/bin/divide-by-zero...
  Reading symbols from /usr/lib/debug/.build-id/14/82d2d64c3383ca479f17bfd17b314295c99f13.debug...
  (gdb) run
  Starting program: /usr/bin/divide-by-zero
  [Thread debugging using libthread_db enabled]
  Using host libthread_db library "/lib/s390x-linux-gnu/libthread_db.so.1".

  Program received signal SIGTRAP, Trace/breakpoint trap.
  0x000002aa00000814 in ?? ()
  (gdb) bt
  #0  0x000002aa00000814 in ?? ()
  #1  0x000003fff7d2baac in __libc_start_call_main (main=0x2aa00000690 <main>, main at entry=<error reading variable: value has been optimized out>, argc=argc at entry=1, argv=argv at entry=0x3ffffffa468)
      at ../sysdeps/nptl/libc_start_call_main.h:58
  #2  0x000003fff7d2bbae in __libc_start_main_impl (main=<optimized out>, argc=1, argv=0x3ffffffa468, init=<optimized out>, fini=<optimized out>, rtld_fini=0x3fff7f85650 <_dl_fini>,
      stack_end=0x3ffffffa3b0) at ../csu/libc-start.c:360
  #3  0x000002aa00000720 in _start ()
  (gdb) info address divide_by_zero
  Symbol "divide_by_zero" is a function at address 0x2aa00000810.
  (gdb)

  So at this point GDB isn't capable of identifying the various symbols
  on the stack, which isn't ideal.

  Now, if I try to step in:

  ubuntu at glibc-proposed:/tmp$ gdb -q /usr/bin/divide-by-zero
  Reading symbols from /usr/bin/divide-by-zero...
  Reading symbols from /usr/lib/debug/.build-id/14/82d2d64c3383ca479f17bfd17b314295c99f13.debug...
  (gdb) start
  Temporary breakpoint 1 at 0x690: file divide-by-zero.c, line 29.
  Starting program: /usr/bin/divide-by-zero
  [Thread debugging using libthread_db enabled]
  Using host libthread_db library "/lib/s390x-linux-gnu/libthread_db.so.1".

  Temporary breakpoint 1, main (argc=1, argv=0x3ffffffa468) at divide-by-zero.c:29
  warning: 29     divide-by-zero.c: No such file or directory
  (gdb) s
  34      in divide-by-zero.c
  (gdb)
  divide_by_zero () at divide-by-zero.c:25
  25      in divide-by-zero.c
  (gdb)
  /build/gdb-nviNEX/gdb-15.1/gdb/infrun.c:2982: internal-error: resume_1: Assertion `pc_in_thread_step_range (pc, tp)' failed.
  A problem internal to GDB has been detected,
  further debugging may prove unreliable.
  ----- Backtrace -----
  0x2aa100a247f ???
  0x2aa104efce5 ???
  0x2aa104eff7f ???
  0x2aa10668c13 ???
  0x2aa102553db ???
  0x2aa10255bd1 ???
  0x2aa10255f5f ???
  0x2aa10259195 ???
  0x2aa1025c315 ???
  0x2aa1025e9a5 ???
  0x2aa10260015 ???
  0x2aa1066951b ???
  0x2aa10669e6d ???
  0x2aa102b01cd ???
  0x2aa102b3607 ???
  0x2aa0ffed839 ???
  0x3ffb142baab __libc_start_call_main
          ../sysdeps/nptl/libc_start_call_main.h:58
  0x3ffb142bbad __libc_start_main_impl
          ../csu/libc-start.c:360
  0x2aa0fff8f8f ???
  0xffffffffffffffff ???
  ---------------------
  /build/gdb-nviNEX/gdb-15.1/gdb/infrun.c:2982: internal-error: resume_1: Assertion `pc_in_thread_step_range (pc, tp)' failed.
  A problem internal to GDB has been detected,
  further debugging may prove unreliable.
  Quit this debugging session? (y or n)

  I can provide a core dump if you think that'd help, but it seems
  trivially reproducible.

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