Re: [Linux-ia64] gdb problem unwinding abort in signal

[David Mosberger <davidm@napali.hpl.hp.com>]

>>>>> On Fri, 11 Apr 2003 13:17:38 -0500, Mario Smarduch <cms063@email.mot.com> said:

  Mario> When our application aborts in the signal handler (no
  Mario> altstack is setup) the stack backtrace discontinues at the
  Mario> signal handler.

  Mario> (gdb) where #0 0x20000000000a6342 in kill () at soinit.c:56
  Mario> #1 0x20000000000a61f0 in raise (sig=6) at
  Mario> ../sysdeps/posix/raise.c:27 #2 0x20000000000a8a70 in abort ()
  Mario> at ../sysdeps/generic/abort.c:88 #3 0x4000000000000910 in
  Mario> sig_report_and_die ()


  Mario> Manually unwinding the stack shows the rp set to
  Mario> ia64_sigtramp(). The privilaged gate page simplifies allot of
  Mario> things, but it poses a problem to our software because we
  Mario> send events for all signals of importance, and count on the
  Mario> core dump to capture the full call trace prior to and
  Mario> including the signal - gdb displays this full backtrace on
  Mario> all other architectures we run on.

  Mario> If this is the problem how does one get around it besides
  Mario> manually unwinding the stack?

There is a gdb patch in the works that will use libunwind for
backtracing purposes.  Unwinding across signal handlers will work just
fine then (at least with reasonably recent kernels).  An old
(alpha-quality) snapshot of such a gdb is at:

	ftp://ftp.hpl.hp.com/pub/linux-ia64/ugdb-ia64-020531.tar.gz

and someone from Red Hat is now working on updating the gdb patch for
libunwind v0.9 (and hopefully on getting it into the official gdb
tree).

	--david