From: Ben Hutchings <ben@decadent.org.uk>
Date: Thu, 10 Sep 2009 01:53:50 +0000 (+0100)
Subject: x86: Fix code patching for paravirt-alternatives on 486
X-Git-Tag: v2.6.32-rc1~711^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5367b6887e7d8c870a5da7d9b8c6e9c207684e43;p=pandora-kernel.git

x86: Fix code patching for paravirt-alternatives on 486

As reported in <http://bugs.debian.org/511703> and
<http://bugs.debian.org/515982>, kernels with paravirt-alternatives
enabled crash in text_poke_early() on at least some 486-class
processors.

The problem is that text_poke_early() itself uses inline functions
affected by paravirt-alternatives and so will modify instructions that
have already been prefetched.  Pentium and later processors will
invalidate the prefetched instructions in this case, but 486-class
processors do not.

Change sync_core() to limit prefetching on 486-class (and 386-class)
processors, and move the call to sync_core() above the call to the
modifiable local_irq_restore().

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
LKML-Reference: <1252547631.3423.134.camel@localhost>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---

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