linux/scripts
Roland McGrath 0b0bf7a3cc [PATCH] vDSO hash-style fix
The latest toolchains can produce a new ELF section in DSOs and
dynamically-linked executables.  The new section ".gnu.hash" replaces
".hash", and allows for more efficient runtime symbol lookups by the
dynamic linker.  The new ld option --hash-style={sysv|gnu|both} controls
whether to produce the old ".hash", the new ".gnu.hash", or both.  In some
new systems such as Fedora Core 6, gcc by default passes --hash-style=gnu
to the linker, so that a standard invocation of "gcc -shared" results in
producing a DSO with only ".gnu.hash".  The new ".gnu.hash" sections need
to be dealt with the same way as ".hash" sections in all respects; only the
dynamic linker cares about their contents.  To work with older dynamic
linkers (i.e.  preexisting releases of glibc), a binary must have the old
".hash" section.  The --hash-style=both option produces binaries that a new
dynamic linker can use more efficiently, but an old dynamic linker can
still handle.

The new section runs afoul of the custom linker scripts used to build vDSO
images for the kernel.  On ia64, the failure mode for this is a boot-time
panic because the vDSO's PT_IA_64_UNWIND segment winds up ill-formed.

This patch addresses the problem in two ways.

First, it mentions ".gnu.hash" in all the linker scripts alongside ".hash".
 This produces correct vDSO images with --hash-style=sysv (or old tools),
with --hash-style=gnu, or with --hash-style=both.

Second, it passes the --hash-style=sysv option when building the vDSO
images, so that ".gnu.hash" is not actually produced.  This is the most
conservative choice for compatibility with any old userland.  There is some
concern that some ancient glibc builds (though not any known old production
system) might choke on --hash-style=both binaries.  The optimizations
provided by the new style of hash section do not really matter for a DSO
with a tiny number of symbols, as the vDSO has.  If someone wants to use
=gnu or =both for their vDSO builds and worry less about that
compatibility, just change the option and the linker script changes will
make any choice work fine.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-31 13:28:43 -07:00
..
basic kconfig: integrate split config into silentoldconfig 2006-06-09 07:31:30 +02:00
genksyms kbuild: replace abort() with exit(1) 2006-06-24 23:46:54 +02:00
kconfig kconfig: enhancing accessibility of lxdialog 2006-07-01 10:05:42 +02:00
ksymoops Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mod kbuild: warn when a moduled uses a symbol marked UNUSED 2006-07-01 11:44:23 +02:00
package kbuild: fix make rpm for powerpc 2006-06-08 20:18:49 +02:00
rt-tester [PATCH] rtmutex: Modify rtmutex-tester to test the setscheduler propagation 2006-06-27 17:32:47 -07:00
.gitignore gitignore: ignore more generated files 2006-01-03 11:35:26 +01:00
bin2c.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
binoffset.c update the email address of Randy Dunlap 2006-01-03 13:37:51 +01:00
bloat-o-meter [PATCH] bloat-o-meter: gcc-4 fix 2006-06-25 10:01:00 -07:00
checkincludes.pl Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
checkstack.pl [PATCH] checkstack: print module names 2006-06-25 10:01:15 -07:00
checkversion.pl kbuild: introduce utsrelease.h 2006-07-03 23:30:54 +02:00
conmakehash.c [PATCH] kbuild: signed char fixes for scripts 2005-07-27 22:27:08 +02:00
export_report.pl kbuild: export-symbol usage report generator 2006-06-24 23:14:02 +02:00
extract-ikconfig [PATCH] extract-ikconfig: don't use --long-options 2006-03-24 07:33:21 -08:00
gcc-version.sh Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
gen_initramfs_list.sh kbuild: fix gen_initramfs_list.sh 2006-04-30 23:56:33 +02:00
hdrcheck.sh Basic implementation of 'make headers_check' 2006-06-18 12:02:10 +01:00
kallsyms.c [PATCH] kallsyms: handle malloc() failure 2006-03-25 08:22:56 -08:00
Kbuild.include [PATCH] vDSO hash-style fix 2006-07-31 13:28:43 -07:00
kernel-doc [PATCH] kernel-doc: ignore __devinit 2006-07-31 13:28:40 -07:00
Lindent [PATCH] Lindent: ignore .indent.pro 2005-07-13 23:09:16 +00:00
Makefile kconfig: move lxdialog to scripts/kconfig/lxdialog 2005-12-16 21:35:19 +01:00
Makefile.build kbuild: fix ia64 breakage after introducing make -rR 2006-07-01 09:58:02 +02:00
Makefile.clean kbuild: change kbuild to not rely on incorrect GNU make behavior 2006-03-06 00:09:51 +01:00
Makefile.headersinst Basic implementation of 'make headers_check' 2006-06-18 12:02:10 +01:00
Makefile.host kbuild: fix ia64 breakage after introducing make -rR 2006-07-01 09:58:02 +02:00
Makefile.lib kbuild: fix ia64 breakage after introducing make -rR 2006-07-01 09:58:02 +02:00
Makefile.modinst kbuild: add option for stripping modules while installing them 2006-06-24 23:16:45 +02:00
Makefile.modpost kbuild: fix ia64 breakage after introducing make -rR 2006-07-01 09:58:02 +02:00
makelst Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mkcompile_h kbuild: "PREEMPT" in UTS_VERSION 2005-07-14 20:18:07 +00:00
mkmakefile kbuild: Do not overwrite makefile as anohter user 2006-05-08 06:55:32 +02:00
mksysmap spelling: s/retreive/retrieve/ 2006-01-10 00:10:13 +01:00
mkuboot.sh Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
mkversion Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
namespace.pl kbuild: fix mode of checkstack.pl and other files. 2006-04-11 13:37:07 +02:00
patch-kernel update the email address of Randy Dunlap 2006-01-03 13:37:51 +01:00
pnmtologo.c Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
profile2linkerlist.pl [PATCH] x86_64: Basic reorder infrastructure 2006-03-25 09:10:56 -08:00
setlocalversion kbuild: append -dirty for updated but uncommited changes 2006-06-17 00:08:17 +02:00
show_delta kbuild: fix mode of checkstack.pl and other files. 2006-04-11 13:37:07 +02:00
ver_linux ver_linux: don't print reiser4progs version if none found 2006-04-05 13:10:19 +02:00