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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
Jose Flavio Aguilar Paulino
9ea6af8ed5 [PPC32] Make PPC32 unwinding work for real. 2007-10-08 12:33:18 -06:00
Jan Kratochvil
57e5696463 Mark Wielaard <mwielaard@redhat.com> writes:
On some systems executable stacks are denied. Since libunwind and the
tests don't actually need executable stacks this patch marks all
assembly files as not needing it.

The original patch comes from frysk:

2007-04-05  Jan Kratochvil  <jan.kratochvil@redhat.com>

    * src/hppa/getcontext.S, src/hppa/setcontext.S, src/hppa/siglongjmp.S,
    src/ia64/Ginstall_cursor.S, src/ia64/Linstall_cursor.S,
    src/ia64/dyn_info_list.S, src/ia64/getcontext.S, src/ia64/longjmp.S,
    src/ia64/setjmp.S, src/ia64/siglongjmp.S, src/ia64/sigsetjmp.S,
    src/ppc64/longjmp.S, src/ppc64/siglongjmp.S, src/x86/longjmp.S,
    src/x86/siglongjmp.S, src/x86_64/longjmp.S, src/x86_64/setcontext.S,
    src/x86_64/siglongjmp.S: Stack should be non-executable, for SELinux.

I added a couple more markers for new files in current libunwind.

Before this patch you would get the following on selinux enabled
systems without allow_exec_stack: error while loading shared
libraries:

libunwind.so.7: cannot enable executable stack as shared object
	requires: Permission denied

After the patch that error disappears and all test results are similar
to the results on systems without executable stack protection.
2007-10-01 08:35:01 -06:00
Jose Flavio Aguilar Paulino
c340d04279 [PPC32] Make get_func_addr() a no-op function.
[PPC64] Add .../lib64 library directory when targeting ppc64.
2007-09-20 11:11:37 -06:00
Jose Flavio Aguilar Paulino
4499bb29a6 [PPC32] First check-in to add preliminary support for Linux/PPC32. 2007-09-12 21:52:25 -06:00