From: Jeremy Fitzhardinge <jeremy@goop.org>
Date: Wed, 30 Jan 2008 12:34:11 +0000 (+0100)
Subject: x86: ignore spurious faults
X-Git-Tag: v2.6.25-rc1~1143^2~9
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5b727a3b0158a129827c21ce3bfb0ba997e8ddd0;p=pandora-kernel.git

x86: ignore spurious faults

When changing a kernel page from RO->RW, it's OK to leave stale TLB
entries around, since doing a global flush is expensive and they pose
no security problem.  They can, however, generate a spurious fault,
which we should catch and simply return from (which will have the
side-effect of reloading the TLB to the current PTE).

This can occur when running under Xen, because it frequently changes
kernel pages from RW->RO->RW to implement Xen's pagetable semantics.
It could also occur when using CONFIG_DEBUG_PAGEALLOC, since it avoids
doing a global TLB flush after changing page permissions.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---

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