]> pilppa.com Git - linux-2.6-omap-h63xx.git/commit
[PATCH] i386: Make COMPAT_VDSO runtime selectable.
authorJeremy Fitzhardinge <jeremy@goop.org>
Wed, 2 May 2007 17:27:12 +0000 (19:27 +0200)
committerAndi Kleen <andi@basil.nowhere.org>
Wed, 2 May 2007 17:27:12 +0000 (19:27 +0200)
commit1dbf527c51c6c20c19869c8125cb5b87c3d09506
treeab480b3eff886e54c6d3c881936f046599e7ea61
parentd4f7a2c18e59e0304a1c733589ce14fc02fec1bd
[PATCH] i386: Make COMPAT_VDSO runtime selectable.

Now that relocation of the VDSO for COMPAT_VDSO users is done at
runtime rather than compile time, it is possible to enable/disable
compat mode at runtime.

This patch allows you to enable COMPAT_VDSO mode with "vdso=2" on the
kernel command line, or via sysctl.  (Switching on a running system
shouldn't be done lightly; any process which was relying on the compat
VDSO will be upset if it goes away.)

The COMPAT_VDSO config option still exists, but if enabled it just
makes vdso_enabled default to VDSO_COMPAT.

+From: Hugh Dickins <hugh@veritas.com>

Fix oops from i386-make-compat_vdso-runtime-selectable.patch.

Even mingetty at system startup finds it easy to trigger an oops
while reading /proc/PID/maps: though it has a good hold on the mm
itself, that cannot stop exit_mm() from resetting tsk->mm to NULL.

(It is usually show_map()'s call to get_gate_vma() which oopses,
and I expect we could change that to check priv->tail_vma instead;
but no matter, even m_start()'s call just after get_task_mm() is racy.)

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Zachary Amsden <zach@vmware.com>
Cc: "Jan Beulich" <JBeulich@novell.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Roland McGrath <roland@redhat.com>
Documentation/kernel-parameters.txt
arch/i386/kernel/sysenter.c
include/asm-i386/page.h