summaryrefslogtreecommitdiffstats
path: root/arch/i386/kernel/cpu
diff options
context:
space:
mode:
authorAndi Kleen <ak@suse.de>2007-07-22 11:12:32 +0200
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-22 11:03:37 -0700
commit8f4e956b313dcccbc7be6f10808952345e3b638c (patch)
treecc8c93fa1faf5e0b608e3a21330a32bd82fe6f47 /arch/i386/kernel/cpu
parent19d36ccdc34f5ed444f8a6af0cbfdb6790eb1177 (diff)
downloadop-kernel-dev-8f4e956b313dcccbc7be6f10808952345e3b638c.zip
op-kernel-dev-8f4e956b313dcccbc7be6f10808952345e3b638c.tar.gz
x86: Stop MCEs and NMIs during code patching
When a machine check or NMI occurs while multiple byte code is patched the CPU could theoretically see an inconsistent instruction and crash. Prevent this by temporarily disabling MCEs and returning early in the NMI handler. Based on discussion with Mathieu Desnoyers. Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/i386/kernel/cpu')
-rw-r--r--arch/i386/kernel/cpu/mcheck/mce.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/arch/i386/kernel/cpu/mcheck/mce.c b/arch/i386/kernel/cpu/mcheck/mce.c
index 56cd485..34c781e 100644
--- a/arch/i386/kernel/cpu/mcheck/mce.c
+++ b/arch/i386/kernel/cpu/mcheck/mce.c
@@ -60,6 +60,20 @@ void mcheck_init(struct cpuinfo_x86 *c)
}
}
+static unsigned long old_cr4 __initdata;
+
+void __init stop_mce(void)
+{
+ old_cr4 = read_cr4();
+ clear_in_cr4(X86_CR4_MCE);
+}
+
+void __init restart_mce(void)
+{
+ if (old_cr4 & X86_CR4_MCE)
+ set_in_cr4(X86_CR4_MCE);
+}
+
static int __init mcheck_disable(char *str)
{
mce_disabled = 1;
OpenPOWER on IntegriCloud