http://sourceware.org/ml/gdb-patches/2013-05/msg00042.html

Subject: [patch] Fix gcore for vDSO (on ppc64)

Hi,

on ppc64 GNU/Linux one gets in live process or kernel-generated core file:

#0  0x00003fff9e946b3c in __pause_nocancel () from /lib64/libc.so.6

#1  0x000000001000080c in handle_alrm (signo=14) at small.c:16

#2  <signal handler called>

#3  0x00003fff9e946b3c in __pause_nocancel () from /lib64/libc.so.6

#4  0x0000000010000914 in main (argc=2, argv=0x3fffcd00dec8) at small.c:32

while with gcore generated core file one gets:

#0  0x00003fff9e946b3c in __pause_nocancel () from /lib64/libc.so.6

#1  0x000000001000080c in handle_alrm (signo=14) at small.c:16

#2  0x00003fff9ea70448 in ?? ()

#3  0x0000000010000914 in main (argc=2, argv=0x3fffcd00dec8) at small.c:32

This is because on ppc64 GNU/Linux the signal handler frame is in vDSO (and

not in libc as on x86_64 GNU/Linux).  And if one has kernel-debuginfo

installed GDB gcore thinks it can omit the vDSO page from core file.

As vDSO cannot be reliably found from link_map it should be rather fully

present in the core file.  Which also gcore_create_callback tries to do but it

gets mistaken by the separate debug info.

It seems pretty obvious patch to me.

Thanks,

Jan

gdb/

2013-05-03  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gcore.c (gcore_create_callback): Ignore sections with

	separate_debug_objfile_backlink != NULL.

--- gdb-7.6-orig/gdb/gcore.c	2013-01-01 07:32:42.000000000 +0100

+++ gdb-7.6/gdb/gcore.c	2013-05-03 03:31:34.795312996 +0200

@@ -428,8 +428,9 @@ gcore_create_callback (CORE_ADDR vaddr,

 	     This BFD was synthesized from reading target memory,

 	     we don't want to omit that.  */

-	  if (((vaddr >= start && vaddr + size <= end)

-	       || (start >= vaddr && end <= vaddr + size))

+	  if (objfile->separate_debug_objfile_backlink == NULL

+	      && ((vaddr >= start && vaddr + size <= end)

+	          || (start >= vaddr && end <= vaddr + size))

 	      && !(bfd_get_file_flags (abfd) & BFD_IN_MEMORY))

 	    {

 	      flags &= ~(SEC_LOAD | SEC_HAS_CONTENTS);