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Re: [review] Fix backtrace of prelinked libc with separate debuginfo
- From: Daniel Jacobowitz <drow at false dot org>
- To: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- Cc: gdb-patches at sourceware dot org
- Date: Tue, 9 Jan 2007 17:43:23 -0500
- Subject: Re: [review] Fix backtrace of prelinked libc with separate debuginfo
- References: <20061029223912.GA24248@host0.dyn.jankratochvil.net>
On Sun, Oct 29, 2006 at 11:39:12PM +0100, Jan Kratochvil wrote:
> It is (I believe) due to the fact the system libc gets prelinked to some
> address but the separate debuginfo file is not updated for the prelinked
> address. `matching_bfd_sections' will fail to match afterwards.
>
> Not sure if the testcase properly fails on all systems, it works for me with
> the prelinking in effect.
Right. It won't fail on Debian even with prelinking - I think this is
because Debian uses binutils' objcopy program, which puts the stripped
symbols in the debug file, but eu-strip leaves them only in the
original file. Which seems pretty strange but that's what it does.
> 2006-10-29 Jan Kratochvil <jan.kratochvil@redhat.com>
>
> * gdb/symtab.c (matching_bfd_sections): Fix VMA matching for objects
> loaded at a different address than stored on the disk.
>
> 2006-10-29 Jan Kratochvil <jan.kratochvil@redhat.com>
>
> * gdb.base/relativedebug.c, gdb.base/relativedebug.exp: New file,
> resolving of PC in libc pause(3) (with possibly different on-disk VMA).
I updated the test case to work with remote targets and then checked
this in.
--
Daniel Jacobowitz
CodeSourcery
2007-01-09 Jan Kratochvil <jan.kratochvil@redhat.com>
* symtab.c (matching_bfd_sections): Fix VMA matching for
prelinked objects.
2007-01-09 Jan Kratochvil <jan.kratochvil@redhat.com>
* gdb.base/relativedebug.c, gdb.base/relativedebug.exp: New files.
Index: symtab.c
===================================================================
RCS file: /cvs/src/src/gdb/symtab.c,v
retrieving revision 1.151
diff -u -p -r1.151 symtab.c
--- symtab.c 9 Jan 2007 17:58:59 -0000 1.151
+++ symtab.c 9 Jan 2007 22:39:14 -0000
@@ -739,8 +739,11 @@ matching_bfd_sections (asection *first,
if (bfd_get_section_size (first) != bfd_get_section_size (second))
return 0;
+ /* In-memory addresses may start at a different offset, relativize them. */
if (bfd_get_section_vma (first->owner, first)
- != bfd_get_section_vma (second->owner, second))
+ - bfd_get_start_address (first->owner)
+ != bfd_get_section_vma (second->owner, second)
+ - bfd_get_start_address (second->owner))
return 0;
if (bfd_get_section_name (first->owner, first) == NULL
Index: testsuite/gdb.base/relativedebug.c
===================================================================
RCS file: testsuite/gdb.base/relativedebug.c
diff -N testsuite/gdb.base/relativedebug.c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/relativedebug.c 9 Jan 2007 22:39:14 -0000
@@ -0,0 +1,37 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2007 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ 02111-1307, USA. */
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <signal.h>
+
+
+static void handler (int signo)
+{
+ abort ();
+}
+
+int main (void)
+{
+ signal (SIGALRM, handler);
+ alarm (1);
+ pause ();
+ pause ();
+ return 0;
+}
Index: testsuite/gdb.base/relativedebug.exp
===================================================================
RCS file: testsuite/gdb.base/relativedebug.exp
diff -N testsuite/gdb.base/relativedebug.exp
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.base/relativedebug.exp 9 Jan 2007 22:39:14 -0000
@@ -0,0 +1,71 @@
+# Copyright 2007 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+if $tracelevel then {
+ strace $tracelevel
+}
+
+set testfile relativedebug
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+ untested "Couldn't compile test program"
+ return -1
+}
+
+# Get things started.
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+runto_main
+
+# pause () -> SIGALRM -> handler () -> abort ()
+gdb_test "continue" "Program received signal SIGABRT.*"
+
+# Backtracing through pause broke if glibc has been prelinked,
+# because the separate debug files in /usr/lib/debug had different
+# base addresses.
+
+# incorrect (#6):
+# (gdb) bt
+# #0 0x00325402 in __kernel_vsyscall ()
+# #1 0x00718f20 in *__GI_raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
+# #2 0x0071a801 in *__GI_abort () at abort.c:88
+# #3 0x0804841f in handler (signo=14) at ./gdb.base/relativedebug.c:27
+# #4 <signal handler called>
+# #5 0x00325402 in __kernel_vsyscall ()
+# #6 0x0077ebc6 in ?? () from /lib/i686/nosegneg/libc.so.6
+# #7 0x08048455 in main () at ./gdb.base/relativedebug.c:34
+# (gdb)
+
+# correct (#6):
+# (gdb) bt
+# #0 0x00b33402 in __kernel_vsyscall ()
+# #1 0x00718f20 in *__GI_raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
+# #2 0x0071a801 in *__GI_abort () at abort.c:88
+# #3 0x0804841f in handler (signo=14) at ./gdb.base/relativedebug.c:27
+# #4 <signal handler called>
+# #5 0x00b33402 in __kernel_vsyscall ()
+# #6 0x0077ebc6 in __pause_nocancel () from /lib/i686/nosegneg/libc.so.6
+# #7 0x08048455 in main () at ./gdb.base/relativedebug.c:34
+# (gdb)
+
+gdb_test "bt" \
+ ".*\[^a-zA-Z\]pause\[^a-zA-Z\].*" \
+ "pause found in backtrace"