x86, mce: add machine check exception count in /proc/interrupts

Useful for debugging, but it's also good general policy
to have a counter for all special interrupts there. This makes it easier
to diagnose where a CPU is spending its time.

[ Impact: feature, debugging tool ]

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
index ac6e030..1156dae 100644
--- a/arch/x86/include/asm/mce.h
+++ b/arch/x86/include/asm/mce.h
@@ -89,6 +89,7 @@
 extern int mce_disabled;
 
 #include <asm/atomic.h>
+#include <linux/percpu.h>
 
 void mce_setup(struct mce *m);
 void mce_log(struct mce *m);
@@ -123,6 +124,8 @@
 
 int mce_available(struct cpuinfo_x86 *c);
 
+DECLARE_PER_CPU(unsigned, mce_exception_count);
+
 void mce_log_therm_throt_event(__u64 status);
 
 extern atomic_t mce_entry;