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/*
* HW NMI watchdog support
*
* started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
*
* Arch specific calls to support NMI watchdog
*
* Bits copied from original nmi.c file
*
*/
#include <asm/apic.h>
#include <linux/smp.h>
#include <linux/cpumask.h>
#include <linux/sched.h>
#include <linux/percpu.h>
#include <linux/cpumask.h>
#include <linux/kernel_stat.h>
#include <asm/mce.h>
#include <linux/nmi.h>
#include <linux/module.h>
/* For reliability, we're prepared to waste bits here. */
static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
static DEFINE_PER_CPU(unsigned, last_irq_sum);
/*
* Take the local apic timer and PIT/HPET into account. We don't
* know which one is active, when we have highres/dyntick on
*/
static inline unsigned int get_timer_irqs(int cpu)
{
unsigned int irqs = per_cpu(irq_stat, cpu).irq0_irqs;
#if defined(CONFIG_X86_LOCAL_APIC)
irqs += per_cpu(irq_stat, cpu).apic_timer_irqs;
#endif
return irqs;
}
static inline int mce_in_progress(void)
{
#if defined(CONFIG_X86_MCE)
return atomic_read(&mce_entry) > 0;
#endif
return 0;
}
int hw_nmi_is_cpu_stuck(struct pt_regs *regs)
{
unsigned int sum;
int cpu = smp_processor_id();
/* FIXME: cheap hack for this check, probably should get its own
* die_notifier handler
*/
if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
static DEFINE_SPINLOCK(lock); /* Serialise the printks */
spin_lock(&lock);
printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
show_regs(regs);
dump_stack();
spin_unlock(&lock);
cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
}
/* if we are doing an mce, just assume the cpu is not stuck */
/* Could check oops_in_progress here too, but it's safer not to */
if (mce_in_progress())
return 0;
/* We determine if the cpu is stuck by checking whether any
* interrupts have happened since we last checked. Of course
* an nmi storm could create false positives, but the higher
* level logic should account for that
*/
sum = get_timer_irqs(cpu);
if (__get_cpu_var(last_irq_sum) == sum) {
return 1;
} else {
__get_cpu_var(last_irq_sum) = sum;
return 0;
}
}
u64 hw_nmi_get_sample_period(void)
{
return cpu_khz * 1000;
}
#ifdef ARCH_HAS_NMI_WATCHDOG
void arch_trigger_all_cpu_backtrace(void)
{
int i;
cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
printk(KERN_INFO "sending NMI to all CPUs:\n");
apic->send_IPI_all(NMI_VECTOR);
/* Wait for up to 10 seconds for all CPUs to do the backtrace */
for (i = 0; i < 10 * 1000; i++) {
if (cpumask_empty(to_cpumask(backtrace_mask)))
break;
mdelay(1);
}
}
#endif
/* STUB calls to mimic old nmi_watchdog behaviour */
#if defined(CONFIG_X86_LOCAL_APIC)
unsigned int nmi_watchdog = NMI_NONE;
EXPORT_SYMBOL(nmi_watchdog);
void acpi_nmi_enable(void) { return; }
void acpi_nmi_disable(void) { return; }
#endif
atomic_t nmi_active = ATOMIC_INIT(0); /* oprofile uses this */
EXPORT_SYMBOL(nmi_active);
int unknown_nmi_panic;
void cpu_nmi_set_wd_enabled(void) { return; }
void stop_apic_nmi_watchdog(void *unused) { return; }
void setup_apic_nmi_watchdog(void *unused) { return; }
int __init check_nmi_watchdog(void) { return 0; }
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