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Author SHA1 Message Date
Lassi Tuura
a9dce3c06e During the stack unwinding process, the return address points to
the instruction after the call for a normal frame. libunwind uses
IP-1 to lookup unwind information. However, this is not necessary for
interrupted frames such as signal frames (or interrupt frames) in
the kernel context.

This patch handles both cases correctly.

Based on work by Mark Wielaard <mwielaard@redhat.com>
2010-04-24 19:16:09 -07:00
Paul Pluzhnikov
84d4150668 Allow caller to block signals.
Greetings,

We use libunwind just for stack traces (I suspect many others do as well).

The use pattern is:

GetStackTrace(void** result, int max_depth)
{
...
  unw_getcontext(&uc);
  unw_init_local(&cursor, &uc);

  while (n < max_depth) {
    if (unw_get_reg(&cursor, UNW_REG_IP, (unw_word_t *) &ip) < 0) {
      break;
    }
    result[n++] = ip;
    if (unw_step(&cursor) <= 0) {
      break;
    }
  }

Given this usage, it is quite convenient for us to block signals (or
prevent signal handlers from re-entering libunwind by other means) at the
"top level", which makes most of the sigprocmask calls performed by
libunwind itself unneccessary.

The second patch in this series adds a configure option which removes most
of the sigprocmask calls.

Attached patch is a preliminary for it -- consolidating all of the
"sigprocmask; mutex_lock;" sequences into lock_acquire and "mutex_unlock;
sigprocmask;" sequences into lock_release.

Thanks,
--
Paul Pluzhnikov

commit 402d15b123d54a7669db7cf17a76dd315094e472
Author: Paul Pluzhnikov <ppluzhnikov@google.com>
Date:   Mon Sep 21 10:18:28 2009 -0700

    Replace "sigprocmask + mutext_lock" with a single lock_acquire.
    Likewise, replace "mutext_unlock + sigprocmask" with lock_release.
2009-09-25 09:35:31 -07:00
Daniel Jacobowitz
3842dac733 Add initial ARM and MIPS support. To support this, also enable the
reading of .debug_frame sections (used in lieu of .eh_frame sections
when they're not available).
2008-02-04 17:16:37 -07:00