[RFA] core files: wrong signal number with threaded program on sparc-solaris

Joel Brobecker
2010-01-28T12:37:18Z

From: brobecke <brobecke@f8352e7e-cb20-0410-8ce7-b5d9e71c585c>

Hello,

We noticed the following problem. Given a threaded program that terminated
because of a SIGABRT (and produced a core file), GDB prints the following
information when loading this core file:

% gdb crash
(gdb) core core
[...]
Core was generated by `./crash'.
Program terminated with signal 9, Killed.
^^^^^^^^^^^^^^^^
#0 0xffffffff7eec9128 in kill () from /lib/64/libc.so.1

The expected behavior is to tell the user that the program terminated
because of a SIGABRT:

Core was generated by `./crash'.
Program terminated with signal 6, Aborted.
#0 0xff2c559c in kill () from /lib/libc.so.1

This issue started appearing after the following change was introduced:

* bfd.m4 (BFD_HAVE_SYS_PROCFS_TYPE): Define _STRUCTURE_PROC
before including procfs.h.
(BFD_HAVE_SYS_PROCFS_TYPE_MEMBER): Likewise.
* configure.in: Added autoconf probe for the pr_fpreg member.
* configure: Regenerated.
* config.in: Regenerated.
* elf.c: Define _STRUCTURE_PROC before including procfs.h.

Basically, instead of using the NT_PRSTATUS notes, we now use the
NT_LWPSTATUS ones. And what happens in our case is that we have
several such notes - I suspect one per thread. The first note has
a signal set to 6, whereas the next one has a signal set to 9.

Interestingly, the same is true iw the NT_PRSTATUS notes, and digging
a little further, I found the following code in elfcore_grok_prstatus
(this is the function that handles NT_PRSTATUS notes):

/* Do not overwrite the core signal if it
has already been set by another thread. */
if (elf_tdata (abfd)->core_signal == 0)
elf_tdata (abfd)->core_signal = prstat.pr_cursig;

It looks like the same logic should be applied in elfcore_grok_lwpstatus.
This is what this patch does.

bfd/ChangeLog:

* elf.c (elfcore_grok_lwpstatus): Do not overwrite the core signal
if it has already been set.

Tested on sparc-solaris by running the GDB testsuite. No regression.
OK to apply?

Thanks,
--
Joel

---
bfd/ChangeLog.GNAT | 5 +++++
bfd/elf.c | 5 ++++-
2 files changed, 9 insertions(+), 1 deletions(-)

diff --git a/bfd/ChangeLog.GNAT b/bfd/ChangeLog.GNAT
index ea483ec..93b4e85 100644
--- a/bfd/ChangeLog.GNAT
+++ b/bfd/ChangeLog.GNAT
@@ -1,3 +1,8 @@
+2010-01-28 Joel Brobecker <brobecker@adacore.com>
+
+ * elf.c (elfcore_grok_lwpstatus): Do not overwrite the core signal
+ if it has already been set.
+
2010-01-01 Joel Brobecker <brobecker@adacore.com>

Revert a local change that was unnecessary.
diff --git a/bfd/elf.c b/bfd/elf.c
index aac3314..19e4695 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -7800,7 +7800,10 @@ elfcore_grok_lwpstatus (bfd *abfd, Elf_Internal_Note *note)
memcpy (&lwpstat, note->descdata, sizeof (lwpstat));

elf_tdata (abfd)->core_lwpid = lwpstat.pr_lwpid;
- elf_tdata (abfd)->core_signal = lwpstat.pr_cursig;
+ /* Do not overwrite the core signal if it has already been set by
+ another thread. */
+ if (elf_tdata (abfd)->core_signal == 0)
+ elf_tdata (abfd)->core_signal = lwpstat.pr_cursig;

/* Make a ".reg/999" section. */

--
1.6.3.3