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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/x86/kernel/apic/hw_nmi.c
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/*

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 *  HW NMI watchdog support

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 *

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 *  started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.

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 *

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 *  Arch specific calls to support NMI watchdog

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 *

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 *  Bits copied from original nmi.c file

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 *

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 */

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#include <asm/apic.h>

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#include <linux/cpumask.h>

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#include <linux/kdebug.h>

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#include <linux/notifier.h>

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#include <linux/kprobes.h>

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#include <linux/nmi.h>

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#include <linux/module.h>

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#include <linux/delay.h>

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#ifdef CONFIG_HARDLOCKUP_DETECTOR

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u64 hw_nmi_get_sample_period(int watchdog_thresh)

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{

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	return (u64)(cpu_khz) * 1000 * watchdog_thresh;

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}

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#endif

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#ifdef arch_trigger_all_cpu_backtrace

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/* For reliability, we're prepared to waste bits here. */

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static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;

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/* "in progress" flag of arch_trigger_all_cpu_backtrace */

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static unsigned long backtrace_flag;

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void arch_trigger_all_cpu_backtrace(void)

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{

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	int i;

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	if (test_and_set_bit(0, &backtrace_flag))

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		/*

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		 * If there is already a trigger_all_cpu_backtrace() in progress

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		 * (backtrace_flag == 1), don't output double cpu dump infos.

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		 */

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		return;

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	cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);

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	printk(KERN_INFO "sending NMI to all CPUs:\n");

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	apic->send_IPI_all(NMI_VECTOR);

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	/* Wait for up to 10 seconds for all CPUs to do the backtrace */

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	for (i = 0; i < 10 * 1000; i++) {

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		if (cpumask_empty(to_cpumask(backtrace_mask)))

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			break;

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		mdelay(1);

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	}

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	clear_bit(0, &backtrace_flag);

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	smp_mb__after_clear_bit();

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}

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static int __kprobes

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arch_trigger_all_cpu_backtrace_handler(struct notifier_block *self,

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			 unsigned long cmd, void *__args)

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{

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	struct die_args *args = __args;

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	struct pt_regs *regs;

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	int cpu;

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	switch (cmd) {

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	case DIE_NMI:

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		break;

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	default:

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		return NOTIFY_DONE;

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	}

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	regs = args->regs;

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	cpu = smp_processor_id();

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	if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {

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		static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED;

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		arch_spin_lock(&lock);

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		printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);

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		show_regs(regs);

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		arch_spin_unlock(&lock);

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		cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));

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		return NOTIFY_STOP;

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	}

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	return NOTIFY_DONE;

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}

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static __read_mostly struct notifier_block backtrace_notifier = {

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	.notifier_call          = arch_trigger_all_cpu_backtrace_handler,

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	.next                   = NULL,

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	.priority               = NMI_LOCAL_LOW_PRIOR,

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};

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static int __init register_trigger_all_cpu_backtrace(void)

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{

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	register_die_notifier(&backtrace_notifier);

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	return 0;

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}

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early_initcall(register_trigger_all_cpu_backtrace);

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#endif

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