Commit-ID: 680b6cfd3cee30a7d997d49430fb73af84523853
Gitweb: http://git.kernel.org/tip/680b6cfd3cee30a7d997d49430fb73af84523853
Author: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx>
AuthorDate: Wed, 26 Aug 2009 16:20:36 +0900
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 26 Aug 2009 20:21:11 +0200
x86, mce: CE in last bank prevents panic by unknown MCE
If MCE handler is called but none of mces_seen have machine
check event which might signal the MCE (i.e. event higher than
MCE_KEEP_SEVERITY), panic with "Machine check from unknown
source" will be taken since the MCE is assumed to be signaled
from external agent or so.
Usually mces_seen never point MCE_KEEP_SEVERITY event such as
CE. But it can happen because initial value of mces_seen is
accidentally modified by mce_no_way_out() - in case if
mce_no_way_out() run through all banks and the last bank has
the CE, mces_seen points the CE and the "panic by unknown" will
not be taken.
This patch fixes this undesired behavior, and clarifies the logic.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Jin Dongming <jin.dongming@xxxxxxxxxxxxxxxxxx>
LKML-Reference: <4A94E244.3020301@xxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Reported-by: Jin Dongming <jin.dongming@xxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/mcheck/mce.c | 8 ++++----
1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 54bd1b2..325559d 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -612,7 +612,7 @@ out:
* This way we prevent any potential data corruption in a unrecoverable case
* and also makes sure always all CPU's errors are examined.
*
- * Also this detects the case of an machine check event coming from outer
+ * Also this detects the case of a machine check event coming from outer
* space (not detected by any CPUs) In this case some external agent wants
* us to shut down, so panic too.
*
@@ -665,7 +665,7 @@ static void mce_reign(void)
* No machine check event found. Must be some external
* source or one CPU is hung. Panic.
*/
- if (!m && tolerant < 3)
+ if (global_worst <= MCE_KEEP_SEVERITY && tolerant < 3)
mce_panic("Machine check from unknown source", NULL, NULL);
/*
@@ -889,11 +889,11 @@ void do_machine_check(struct pt_regs *regs, long error_code)
mce_setup(&m);
m.mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS);
- no_way_out = mce_no_way_out(&m, &msg);
-
final = &__get_cpu_var(mces_seen);
*final = m;
+ no_way_out = mce_no_way_out(&m, &msg);
+
barrier();
/*
--
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