[review] Fix backtrace of prelinked libc with separate debuginfo

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

Hi,

currently (on Fedora Core 6) after installation of /usr/lib/debug separate
debuginfo files the backtraces no longer display some libc functions:

#5  <signal handler called>
#6  0x00c98402 in __kernel_vsyscall ()
#7  0x0077ebc6 in ?? () from /lib/i686/nosegneg/libc.so.6
#8  0x08048444 in main () at doublesym.c:15

while after `rm -rf /usr/lib/debug':

#5  <signal handler called>
#6  0x0087b402 in __kernel_vsyscall ()
#7  0x0077ebc6 in __pause_nocancel () from /lib/i686/nosegneg/libc.so.6
#8  0x08048444 in main () at doublesym.c:15

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.


Regards,
Jan

Attachment: gdb-cvs-relativedebug.patch
Description: Text document