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>

arch/x86/include/asm/mce.h

@@ -89,6 +89,7 @@ struct mce_log {
 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 @@ static inline void mce_amd_feature_init(struct cpuinfo_x86 *c) { }
 
 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;

arch/x86/kernel/cpu/mcheck/mce.c

@@ -57,6 +57,8 @@ int				mce_disabled;
 
 atomic_t mce_entry;
 
+DEFINE_PER_CPU(unsigned, mce_exception_count);
+
 /*
  * Tolerant levels:
  *   0: always panic on uncorrected errors, log corrected errors
@@ -359,6 +361,8 @@ void do_machine_check(struct pt_regs *regs, long error_code)
 
 	atomic_inc(&mce_entry);
 
+	__get_cpu_var(mce_exception_count)++;
+
 	if (notify_die(DIE_NMI, "machine check", regs, error_code,
 			   18, SIGKILL) == NOTIFY_STOP)
 		goto out;

arch/x86/kernel/irq.c

@@ -12,6 +12,7 @@
 #include <asm/io_apic.h>
 #include <asm/irq.h>
 #include <asm/idle.h>
+#include <asm/mce.h>
 
 atomic_t irq_err_count;
 
@@ -93,6 +94,12 @@ static int show_other_interrupts(struct seq_file *p, int prec)
 		seq_printf(p, "%10u ", irq_stats(j)->irq_threshold_count);
 	seq_printf(p, "  Threshold APIC interrupts\n");
 # endif
+#endif
+#if defined(CONFIG_X86_MCE) && defined(CONFIG_X86_64)
+	seq_printf(p, "%*s: ", prec, "MCE");
+	for_each_online_cpu(j)
+		seq_printf(p, "%10u ", per_cpu(mce_exception_count, j));
+	seq_printf(p, "  Machine check exceptions\n");
 #endif
 	seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));
 #if defined(CONFIG_X86_IO_APIC)
@@ -161,6 +168,9 @@ u64 arch_irq_stat_cpu(unsigned int cpu)
 {
 	u64 sum = irq_stats(cpu)->__nmi_count;
 
+#if defined(CONFIG_X86_MCE) && defined(CONFIG_X86_64)
+	sum += per_cpu(mce_exception_count, cpu);
+#endif
 #ifdef CONFIG_X86_LOCAL_APIC
 	sum += irq_stats(cpu)->apic_timer_irqs;
 	sum += irq_stats(cpu)->irq_spurious_count;