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Diffstat (limited to 'arch/i386/kernel/nmi.c')
-rw-r--r--arch/i386/kernel/nmi.c60
1 files changed, 44 insertions, 16 deletions
diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c
index 3e8e3adb0489..a5e34d655965 100644
--- a/arch/i386/kernel/nmi.c
+++ b/arch/i386/kernel/nmi.c
@@ -22,6 +22,7 @@
#include <linux/percpu.h>
#include <linux/dmi.h>
#include <linux/kprobes.h>
+#include <linux/cpumask.h>
#include <asm/smp.h>
#include <asm/nmi.h>
@@ -42,6 +43,8 @@ int nmi_watchdog_enabled;
static DEFINE_PER_CPU(unsigned long, perfctr_nmi_owner);
static DEFINE_PER_CPU(unsigned long, evntsel_nmi_owner[3]);
+static cpumask_t backtrace_mask = CPU_MASK_NONE;
+
/* this number is calculated from Intel's MSR_P4_CRU_ESCR5 register and it's
* offset from MSR_P4_BSU_ESCR0. It will be the max for all platforms (for now)
*/
@@ -192,6 +195,8 @@ static __cpuinit inline int nmi_known_cpu(void)
return 0;
}
+static int endflag __initdata = 0;
+
#ifdef CONFIG_SMP
/* The performance counters used by NMI_LOCAL_APIC don't trigger when
* the CPU is idle. To make sure the NMI watchdog really ticks on all
@@ -199,7 +204,6 @@ static __cpuinit inline int nmi_known_cpu(void)
*/
static __init void nmi_cpu_busy(void *data)
{
- volatile int *endflag = data;
local_irq_enable_in_hardirq();
/* Intentionally don't use cpu_relax here. This is
to make sure that the performance counter really ticks,
@@ -207,23 +211,22 @@ static __init void nmi_cpu_busy(void *data)
pause instruction. On a real HT machine this is fine because
all other CPUs are busy with "useless" delay loops and don't
care if they get somewhat less cycles. */
- while (*endflag == 0)
- barrier();
+ while (endflag == 0)
+ mb();
}
#endif
static int __init check_nmi_watchdog(void)
{
- volatile int endflag = 0;
unsigned int *prev_nmi_count;
int cpu;
/* Enable NMI watchdog for newer systems.
- Actually it should be safe for most systems before 2004 too except
- for some IBM systems that corrupt registers when NMI happens
- during SMM. Unfortunately we don't have more exact information
- on these and use this coarse check. */
- if (nmi_watchdog == NMI_DEFAULT && dmi_get_year(DMI_BIOS_DATE) >= 2004)
+ Probably safe on most older systems too, but let's be careful.
+ IBM ThinkPads use INT10 inside SMM and that allows early NMI inside SMM
+ which hangs the system. Disable watchdog for all thinkpads */
+ if (nmi_watchdog == NMI_DEFAULT && dmi_get_year(DMI_BIOS_DATE) >= 2004 &&
+ !dmi_name_in_vendors("ThinkPad"))
nmi_watchdog = NMI_LOCAL_APIC;
if ((nmi_watchdog == NMI_NONE) || (nmi_watchdog == NMI_DEFAULT))
@@ -867,14 +870,16 @@ static unsigned int
void touch_nmi_watchdog (void)
{
- int i;
+ if (nmi_watchdog > 0) {
+ unsigned cpu;
- /*
- * Just reset the alert counters, (other CPUs might be
- * spinning on locks we hold):
- */
- for_each_possible_cpu(i)
- alert_counter[i] = 0;
+ /*
+ * Just reset the alert counters, (other CPUs might be
+ * spinning on locks we hold):
+ */
+ for_each_present_cpu (cpu)
+ alert_counter[cpu] = 0;
+ }
/*
* Tickle the softlockup detector too:
@@ -907,6 +912,16 @@ __kprobes int nmi_watchdog_tick(struct pt_regs * regs, unsigned reason)
touched = 1;
}
+ if (cpu_isset(cpu, backtrace_mask)) {
+ static DEFINE_SPINLOCK(lock); /* Serialise the printks */
+
+ spin_lock(&lock);
+ printk("NMI backtrace for cpu %d\n", cpu);
+ dump_stack();
+ spin_unlock(&lock);
+ cpu_clear(cpu, backtrace_mask);
+ }
+
sum = per_cpu(irq_stat, cpu).apic_timer_irqs;
/* if the apic timer isn't firing, this cpu isn't doing much */
@@ -1033,6 +1048,19 @@ int proc_nmi_enabled(struct ctl_table *table, int write, struct file *file,
#endif
+void __trigger_all_cpu_backtrace(void)
+{
+ int i;
+
+ backtrace_mask = cpu_online_map;
+ /* Wait for up to 10 seconds for all CPUs to do the backtrace */
+ for (i = 0; i < 10 * 1000; i++) {
+ if (cpus_empty(backtrace_mask))
+ break;
+ mdelay(1);
+ }
+}
+
EXPORT_SYMBOL(nmi_active);
EXPORT_SYMBOL(nmi_watchdog);
EXPORT_SYMBOL(avail_to_resrv_perfctr_nmi);