[linux-2.6-block.git] / arch / powerpc / kernel / watchdog.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Watchdog support on powerpc systems.
 *
 * Copyright 2017, IBM Corporation.
 *
 * This uses code from arch/sparc/kernel/nmi.c and kernel/watchdog.c
 */

#define pr_fmt(fmt) "watchdog: " fmt

#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/init.h>
#include <linux/percpu.h>
#include <linux/cpu.h>
#include <linux/nmi.h>
#include <linux/module.h>
#include <linux/export.h>
#include <linux/kprobes.h>
#include <linux/hardirq.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/kdebug.h>
#include <linux/sched/debug.h>
#include <linux/delay.h>
#include <linux/smp.h>

#include <asm/paca.h>

/*
 * The powerpc watchdog ensures that each CPU is able to service timers.
 * The watchdog sets up a simple timer on each CPU to run once per timer
 * period, and updates a per-cpu timestamp and a "pending" cpumask. This is
 * the heartbeat.
 *
 * Then there are two systems to check that the heartbeat is still running.
 * The local soft-NMI, and the SMP checker.
 *
 * The soft-NMI checker can detect lockups on the local CPU. When interrupts
 * are disabled with local_irq_disable(), platforms that use soft-masking
 * can leave hardware interrupts enabled and handle them with a masked
 * interrupt handler. The masked handler can send the timer interrupt to the
 * watchdog's soft_nmi_interrupt(), which appears to Linux as an NMI
 * interrupt, and can be used to detect CPUs stuck with IRQs disabled.
 *
 * The soft-NMI checker will compare the heartbeat timestamp for this CPU
 * with the current time, and take action if the difference exceeds the
 * watchdog threshold.
 *
 * The limitation of the soft-NMI watchdog is that it does not work when
 * interrupts are hard disabled or otherwise not being serviced. This is
 * solved by also having a SMP watchdog where all CPUs check all other
 * CPUs heartbeat.
 *
 * The SMP checker can detect lockups on other CPUs. A gobal "pending"
 * cpumask is kept, containing all CPUs which enable the watchdog. Each
 * CPU clears their pending bit in their heartbeat timer. When the bitmask
 * becomes empty, the last CPU to clear its pending bit updates a global
 * timestamp and refills the pending bitmask.
 *
 * In the heartbeat timer, if any CPU notices that the global timestamp has
 * not been updated for a period exceeding the watchdog threshold, then it
 * means the CPU(s) with their bit still set in the pending mask have had
 * their heartbeat stop, and action is taken.
 *
 * Some platforms implement true NMI IPIs, which can by used by the SMP
 * watchdog to detect an unresponsive CPU and pull it out of its stuck
 * state with the NMI IPI, to get crash/debug data from it. This way the
 * SMP watchdog can detect hardware interrupts off lockups.
 */

static cpumask_t wd_cpus_enabled __read_mostly;

static u64 wd_panic_timeout_tb __read_mostly; /* timebase ticks until panic */
static u64 wd_smp_panic_timeout_tb __read_mostly; /* panic other CPUs */

static u64 wd_timer_period_ms __read_mostly;  /* interval between heartbeat */

static DEFINE_PER_CPU(struct timer_list, wd_timer);
static DEFINE_PER_CPU(u64, wd_timer_tb);

/* SMP checker bits */
static unsigned long __wd_smp_lock;
static cpumask_t wd_smp_cpus_pending;
static cpumask_t wd_smp_cpus_stuck;
static u64 wd_smp_last_reset_tb;

static inline void wd_smp_lock(unsigned long *flags)
{
	/*
	 * Avoid locking layers if possible.
	 * This may be called from low level interrupt handlers at some
	 * point in future.
	 */
	raw_local_irq_save(*flags);
	hard_irq_disable(); /* Make it soft-NMI safe */
	while (unlikely(test_and_set_bit_lock(0, &__wd_smp_lock))) {
		raw_local_irq_restore(*flags);
		spin_until_cond(!test_bit(0, &__wd_smp_lock));
		raw_local_irq_save(*flags);
		hard_irq_disable();
	}
}

static inline void wd_smp_unlock(unsigned long *flags)
{
	clear_bit_unlock(0, &__wd_smp_lock);
	raw_local_irq_restore(*flags);
}

static void wd_lockup_ipi(struct pt_regs *regs)
{
	pr_emerg("CPU %d Hard LOCKUP\n", raw_smp_processor_id());
	print_modules();
	print_irqtrace_events(current);
	if (regs)
		show_regs(regs);
	else
		dump_stack();

	/* Do not panic from here because that can recurse into NMI IPI layer */
}

static void set_cpumask_stuck(const struct cpumask *cpumask, u64 tb)
{
	cpumask_or(&wd_smp_cpus_stuck, &wd_smp_cpus_stuck, cpumask);
	cpumask_andnot(&wd_smp_cpus_pending, &wd_smp_cpus_pending, cpumask);
	if (cpumask_empty(&wd_smp_cpus_pending)) {
		wd_smp_last_reset_tb = tb;
		cpumask_andnot(&wd_smp_cpus_pending,
				&wd_cpus_enabled,
				&wd_smp_cpus_stuck);
	}
}
static void set_cpu_stuck(int cpu, u64 tb)
{
	set_cpumask_stuck(cpumask_of(cpu), tb);
}

static void watchdog_smp_panic(int cpu, u64 tb)
{
	unsigned long flags;
	int c;

	wd_smp_lock(&flags);
	/* Double check some things under lock */
	if ((s64)(tb - wd_smp_last_reset_tb) < (s64)wd_smp_panic_timeout_tb)
		goto out;
	if (cpumask_test_cpu(cpu, &wd_smp_cpus_pending))
		goto out;
	if (cpumask_weight(&wd_smp_cpus_pending) == 0)
		goto out;

	pr_emerg("CPU %d detected hard LOCKUP on other CPUs %*pbl\n",
		 cpu, cpumask_pr_args(&wd_smp_cpus_pending));

	if (!sysctl_hardlockup_all_cpu_backtrace) {
		/*
		 * Try to trigger the stuck CPUs, unless we are going to
		 * get a backtrace on all of them anyway.
		 */
		for_each_cpu(c, &wd_smp_cpus_pending) {
			if (c == cpu)
				continue;
			smp_send_nmi_ipi(c, wd_lockup_ipi, 1000000);
		}
		smp_flush_nmi_ipi(1000000);
	}

	/* Take the stuck CPUs out of the watch group */
	set_cpumask_stuck(&wd_smp_cpus_pending, tb);

	wd_smp_unlock(&flags);

	printk_safe_flush();
	/*
	 * printk_safe_flush() seems to require another print
	 * before anything actually goes out to console.
	 */
	if (sysctl_hardlockup_all_cpu_backtrace)
		trigger_allbutself_cpu_backtrace();

	if (hardlockup_panic)
		nmi_panic(NULL, "Hard LOCKUP");

	return;

out:
	wd_smp_unlock(&flags);
}

static void wd_smp_clear_cpu_pending(int cpu, u64 tb)
{
	if (!cpumask_test_cpu(cpu, &wd_smp_cpus_pending)) {
		if (unlikely(cpumask_test_cpu(cpu, &wd_smp_cpus_stuck))) {
			unsigned long flags;

			pr_emerg("CPU %d became unstuck\n", cpu);
			wd_smp_lock(&flags);
			cpumask_clear_cpu(cpu, &wd_smp_cpus_stuck);
			wd_smp_unlock(&flags);
		}
		return;
	}
	cpumask_clear_cpu(cpu, &wd_smp_cpus_pending);
	if (cpumask_empty(&wd_smp_cpus_pending)) {
		unsigned long flags;

		wd_smp_lock(&flags);
		if (cpumask_empty(&wd_smp_cpus_pending)) {
			wd_smp_last_reset_tb = tb;
			cpumask_andnot(&wd_smp_cpus_pending,
					&wd_cpus_enabled,
					&wd_smp_cpus_stuck);
		}
		wd_smp_unlock(&flags);
	}
}

static void watchdog_timer_interrupt(int cpu)
{
	u64 tb = get_tb();

	per_cpu(wd_timer_tb, cpu) = tb;

	wd_smp_clear_cpu_pending(cpu, tb);

	if ((s64)(tb - wd_smp_last_reset_tb) >= (s64)wd_smp_panic_timeout_tb)
		watchdog_smp_panic(cpu, tb);
}

void soft_nmi_interrupt(struct pt_regs *regs)
{
	unsigned long flags;
	int cpu = raw_smp_processor_id();
	u64 tb;

	if (!cpumask_test_cpu(cpu, &wd_cpus_enabled))
		return;

	nmi_enter();

	__this_cpu_inc(irq_stat.soft_nmi_irqs);

	tb = get_tb();
	if (tb - per_cpu(wd_timer_tb, cpu) >= wd_panic_timeout_tb) {
		per_cpu(wd_timer_tb, cpu) = tb;

		wd_smp_lock(&flags);
		if (cpumask_test_cpu(cpu, &wd_smp_cpus_stuck)) {
			wd_smp_unlock(&flags);
			goto out;
		}
		set_cpu_stuck(cpu, tb);

		pr_emerg("CPU %d self-detected hard LOCKUP @ %pS\n", cpu, (void *)regs->nip);
		print_modules();
		print_irqtrace_events(current);
		show_regs(regs);

		wd_smp_unlock(&flags);

		if (sysctl_hardlockup_all_cpu_backtrace)
			trigger_allbutself_cpu_backtrace();

		if (hardlockup_panic)
			nmi_panic(regs, "Hard LOCKUP");
	}
	if (wd_panic_timeout_tb < 0x7fffffff)
		mtspr(SPRN_DEC, wd_panic_timeout_tb);

out:
	nmi_exit();
}

static void wd_timer_reset(unsigned int cpu, struct timer_list *t)
{
	t->expires = jiffies + msecs_to_jiffies(wd_timer_period_ms);
	if (wd_timer_period_ms > 1000)
		t->expires = __round_jiffies_up(t->expires, cpu);
	add_timer_on(t, cpu);
}

static void wd_timer_fn(struct timer_list *t)
{
	int cpu = smp_processor_id();

	watchdog_timer_interrupt(cpu);

	wd_timer_reset(cpu, t);
}

void arch_touch_nmi_watchdog(void)
{
	unsigned long ticks = tb_ticks_per_usec * wd_timer_period_ms * 1000;
	int cpu = smp_processor_id();
	u64 tb = get_tb();

	if (tb - per_cpu(wd_timer_tb, cpu) >= ticks) {
		per_cpu(wd_timer_tb, cpu) = tb;
		wd_smp_clear_cpu_pending(cpu, tb);
	}
}
EXPORT_SYMBOL(arch_touch_nmi_watchdog);

static void start_watchdog_timer_on(unsigned int cpu)
{
	struct timer_list *t = per_cpu_ptr(&wd_timer, cpu);

	per_cpu(wd_timer_tb, cpu) = get_tb();

	timer_setup(t, wd_timer_fn, TIMER_PINNED);
	wd_timer_reset(cpu, t);
}

static void stop_watchdog_timer_on(unsigned int cpu)
{
	struct timer_list *t = per_cpu_ptr(&wd_timer, cpu);

	del_timer_sync(t);
}

static int start_wd_on_cpu(unsigned int cpu)
{
	unsigned long flags;

	if (cpumask_test_cpu(cpu, &wd_cpus_enabled)) {
		WARN_ON(1);
		return 0;
	}

	if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
		return 0;

	if (!cpumask_test_cpu(cpu, &watchdog_cpumask))
		return 0;

	wd_smp_lock(&flags);
	cpumask_set_cpu(cpu, &wd_cpus_enabled);
	if (cpumask_weight(&wd_cpus_enabled) == 1) {
		cpumask_set_cpu(cpu, &wd_smp_cpus_pending);
		wd_smp_last_reset_tb = get_tb();
	}
	wd_smp_unlock(&flags);

	start_watchdog_timer_on(cpu);

	return 0;
}

static int stop_wd_on_cpu(unsigned int cpu)
{
	unsigned long flags;

	if (!cpumask_test_cpu(cpu, &wd_cpus_enabled))
		return 0; /* Can happen in CPU unplug case */

	stop_watchdog_timer_on(cpu);

	wd_smp_lock(&flags);
	cpumask_clear_cpu(cpu, &wd_cpus_enabled);
	wd_smp_unlock(&flags);

	wd_smp_clear_cpu_pending(cpu, get_tb());

	return 0;
}

static void watchdog_calc_timeouts(void)
{
	wd_panic_timeout_tb = watchdog_thresh * ppc_tb_freq;

	/* Have the SMP detector trigger a bit later */
	wd_smp_panic_timeout_tb = wd_panic_timeout_tb * 3 / 2;

	/* 2/5 is the factor that the perf based detector uses */
	wd_timer_period_ms = watchdog_thresh * 1000 * 2 / 5;
}

void watchdog_nmi_stop(void)
{
	int cpu;

	for_each_cpu(cpu, &wd_cpus_enabled)
		stop_wd_on_cpu(cpu);
}

void watchdog_nmi_start(void)
{
	int cpu;

	watchdog_calc_timeouts();
	for_each_cpu_and(cpu, cpu_online_mask, &watchdog_cpumask)
		start_wd_on_cpu(cpu);
}

/*
 * Invoked from core watchdog init.
 */
int __init watchdog_nmi_probe(void)
{
	int err;

	err = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
					"powerpc/watchdog:online",
					start_wd_on_cpu, stop_wd_on_cpu);
	if (err < 0) {
		pr_warn("could not be initialized");
		return err;
	}
	return 0;
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
2104180a NP	2	/*
	3	* Watchdog support on powerpc systems.
	4	*
	5	* Copyright 2017, IBM Corporation.
	6	*
	7	* This uses code from arch/sparc/kernel/nmi.c and kernel/watchdog.c
	8	*/
d8fa82e0 ME	9
	10	#define pr_fmt(fmt) "watchdog: " fmt
	11
2104180a NP	12	#include <linux/kernel.h>
	13	#include <linux/param.h>
	14	#include <linux/init.h>
	15	#include <linux/percpu.h>
	16	#include <linux/cpu.h>
	17	#include <linux/nmi.h>
	18	#include <linux/module.h>
	19	#include <linux/export.h>
	20	#include <linux/kprobes.h>
	21	#include <linux/hardirq.h>
	22	#include <linux/reboot.h>
	23	#include <linux/slab.h>
	24	#include <linux/kdebug.h>
	25	#include <linux/sched/debug.h>
	26	#include <linux/delay.h>
	27	#include <linux/smp.h>
	28
	29	#include <asm/paca.h>
	30
	31	/*
723b1133 NP	32	* The powerpc watchdog ensures that each CPU is able to service timers.
	33	* The watchdog sets up a simple timer on each CPU to run once per timer
	34	* period, and updates a per-cpu timestamp and a "pending" cpumask. This is
	35	* the heartbeat.
2104180a	36	*
723b1133 NP	37	* Then there are two systems to check that the heartbeat is still running.
723b1133 NP	38	* The local soft-NMI, and the SMP checker.
2104180a	39	*
723b1133 NP	40	* The soft-NMI checker can detect lockups on the local CPU. When interrupts
	41	* are disabled with local_irq_disable(), platforms that use soft-masking
	42	* can leave hardware interrupts enabled and handle them with a masked
	43	* interrupt handler. The masked handler can send the timer interrupt to the
	44	* watchdog's soft_nmi_interrupt(), which appears to Linux as an NMI
	45	* interrupt, and can be used to detect CPUs stuck with IRQs disabled.
	46	*
	47	* The soft-NMI checker will compare the heartbeat timestamp for this CPU
	48	* with the current time, and take action if the difference exceeds the
	49	* watchdog threshold.
	50	*
	51	* The limitation of the soft-NMI watchdog is that it does not work when
	52	* interrupts are hard disabled or otherwise not being serviced. This is
	53	* solved by also having a SMP watchdog where all CPUs check all other
	54	* CPUs heartbeat.
	55	*
	56	* The SMP checker can detect lockups on other CPUs. A gobal "pending"
	57	* cpumask is kept, containing all CPUs which enable the watchdog. Each
	58	* CPU clears their pending bit in their heartbeat timer. When the bitmask
	59	* becomes empty, the last CPU to clear its pending bit updates a global
	60	* timestamp and refills the pending bitmask.
	61	*
	62	* In the heartbeat timer, if any CPU notices that the global timestamp has
	63	* not been updated for a period exceeding the watchdog threshold, then it
	64	* means the CPU(s) with their bit still set in the pending mask have had
	65	* their heartbeat stop, and action is taken.
	66	*
	67	* Some platforms implement true NMI IPIs, which can by used by the SMP
	68	* watchdog to detect an unresponsive CPU and pull it out of its stuck
	69	* state with the NMI IPI, to get crash/debug data from it. This way the
	70	* SMP watchdog can detect hardware interrupts off lockups.
2104180a NP	71	*/
	72
	73	static cpumask_t wd_cpus_enabled __read_mostly;
	74
	75	static u64 wd_panic_timeout_tb __read_mostly; /* timebase ticks until panic */
	76	static u64 wd_smp_panic_timeout_tb __read_mostly; /* panic other CPUs */
	77
	78	static u64 wd_timer_period_ms __read_mostly; /* interval between heartbeat */
	79
	80	static DEFINE_PER_CPU(struct timer_list, wd_timer);
	81	static DEFINE_PER_CPU(u64, wd_timer_tb);
	82
723b1133	83	/* SMP checker bits */
2104180a NP	84	static unsigned long __wd_smp_lock;
	85	static cpumask_t wd_smp_cpus_pending;
	86	static cpumask_t wd_smp_cpus_stuck;
	87	static u64 wd_smp_last_reset_tb;
	88
	89	static inline void wd_smp_lock(unsigned long *flags)
	90	{
	91	/*
	92	* Avoid locking layers if possible.
	93	* This may be called from low level interrupt handlers at some
	94	* point in future.
	95	*/
d8e2a405 NP	96	raw_local_irq_save(*flags);
	97	hard_irq_disable(); /* Make it soft-NMI safe */
	98	while (unlikely(test_and_set_bit_lock(0, &__wd_smp_lock))) {
	99	raw_local_irq_restore(*flags);
	100	spin_until_cond(!test_bit(0, &__wd_smp_lock));
	101	raw_local_irq_save(*flags);
	102	hard_irq_disable();
	103	}
2104180a NP	104	}
	105
	106	static inline void wd_smp_unlock(unsigned long *flags)
	107	{
	108	clear_bit_unlock(0, &__wd_smp_lock);
d8e2a405	109	raw_local_irq_restore(*flags);
2104180a NP	110	}
	111
	112	static void wd_lockup_ipi(struct pt_regs *regs)
	113	{
d8fa82e0	114	pr_emerg("CPU %d Hard LOCKUP\n", raw_smp_processor_id());
2104180a NP	115	print_modules();
	116	print_irqtrace_events(current);
	117	if (regs)
	118	show_regs(regs);
	119	else
	120	dump_stack();
	121
842dc1db	122	/* Do not panic from here because that can recurse into NMI IPI layer */
2104180a NP	123	}
2104180a NP	124
87607a30	125	static void set_cpumask_stuck(const struct cpumask *cpumask, u64 tb)
2104180a	126	{
87607a30 NP	127	cpumask_or(&wd_smp_cpus_stuck, &wd_smp_cpus_stuck, cpumask);
87607a30 NP	128	cpumask_andnot(&wd_smp_cpus_pending, &wd_smp_cpus_pending, cpumask);
2104180a NP	129	if (cpumask_empty(&wd_smp_cpus_pending)) {
	130	wd_smp_last_reset_tb = tb;
	131	cpumask_andnot(&wd_smp_cpus_pending,
	132	&wd_cpus_enabled,
	133	&wd_smp_cpus_stuck);
	134	}
	135	}
87607a30 NP	136	static void set_cpu_stuck(int cpu, u64 tb)
	137	{
	138	set_cpumask_stuck(cpumask_of(cpu), tb);
	139	}
2104180a NP	140
	141	static void watchdog_smp_panic(int cpu, u64 tb)
	142	{
	143	unsigned long flags;
	144	int c;
	145
	146	wd_smp_lock(&flags);
	147	/* Double check some things under lock */
	148	if ((s64)(tb - wd_smp_last_reset_tb) < (s64)wd_smp_panic_timeout_tb)
	149	goto out;
	150	if (cpumask_test_cpu(cpu, &wd_smp_cpus_pending))
	151	goto out;
	152	if (cpumask_weight(&wd_smp_cpus_pending) == 0)
	153	goto out;
	154
d8fa82e0 ME	155	pr_emerg("CPU %d detected hard LOCKUP on other CPUs %*pbl\n",
d8fa82e0 ME	156	cpu, cpumask_pr_args(&wd_smp_cpus_pending));
2104180a	157
d58fdd9d NP	158	if (!sysctl_hardlockup_all_cpu_backtrace) {
	159	/*
	160	* Try to trigger the stuck CPUs, unless we are going to
	161	* get a backtrace on all of them anyway.
	162	*/
	163	for_each_cpu(c, &wd_smp_cpus_pending) {
	164	if (c == cpu)
	165	continue;
	166	smp_send_nmi_ipi(c, wd_lockup_ipi, 1000000);
	167	}
	168	smp_flush_nmi_ipi(1000000);
2104180a	169	}
2104180a	170
87607a30 NP	171	/* Take the stuck CPUs out of the watch group */
87607a30 NP	172	set_cpumask_stuck(&wd_smp_cpus_pending, tb);
2104180a	173
2104180a NP	174	wd_smp_unlock(&flags);
	175
	176	printk_safe_flush();
	177	/*
	178	* printk_safe_flush() seems to require another print
	179	* before anything actually goes out to console.
	180	*/
	181	if (sysctl_hardlockup_all_cpu_backtrace)
	182	trigger_allbutself_cpu_backtrace();
	183
	184	if (hardlockup_panic)
	185	nmi_panic(NULL, "Hard LOCKUP");
8e236921 NP	186
	187	return;
	188
	189	out:
	190	wd_smp_unlock(&flags);
2104180a NP	191	}
	192
	193	static void wd_smp_clear_cpu_pending(int cpu, u64 tb)
	194	{
	195	if (!cpumask_test_cpu(cpu, &wd_smp_cpus_pending)) {
	196	if (unlikely(cpumask_test_cpu(cpu, &wd_smp_cpus_stuck))) {
	197	unsigned long flags;
	198
d8fa82e0	199	pr_emerg("CPU %d became unstuck\n", cpu);
2104180a NP	200	wd_smp_lock(&flags);
	201	cpumask_clear_cpu(cpu, &wd_smp_cpus_stuck);
	202	wd_smp_unlock(&flags);
	203	}
	204	return;
	205	}
	206	cpumask_clear_cpu(cpu, &wd_smp_cpus_pending);
	207	if (cpumask_empty(&wd_smp_cpus_pending)) {
	208	unsigned long flags;
	209
	210	wd_smp_lock(&flags);
	211	if (cpumask_empty(&wd_smp_cpus_pending)) {
	212	wd_smp_last_reset_tb = tb;
	213	cpumask_andnot(&wd_smp_cpus_pending,
	214	&wd_cpus_enabled,
	215	&wd_smp_cpus_stuck);
	216	}
	217	wd_smp_unlock(&flags);
	218	}
	219	}
	220
	221	static void watchdog_timer_interrupt(int cpu)
	222	{
	223	u64 tb = get_tb();
	224
	225	per_cpu(wd_timer_tb, cpu) = tb;
	226
	227	wd_smp_clear_cpu_pending(cpu, tb);
	228
	229	if ((s64)(tb - wd_smp_last_reset_tb) >= (s64)wd_smp_panic_timeout_tb)
	230	watchdog_smp_panic(cpu, tb);
	231	}
	232
	233	void soft_nmi_interrupt(struct pt_regs *regs)
	234	{
	235	unsigned long flags;
	236	int cpu = raw_smp_processor_id();
	237	u64 tb;
	238
	239	if (!cpumask_test_cpu(cpu, &wd_cpus_enabled))
	240	return;
	241
	242	nmi_enter();
04019bf8 NP	243
	244	__this_cpu_inc(irq_stat.soft_nmi_irqs);
	245
2104180a NP	246	tb = get_tb();
	247	if (tb - per_cpu(wd_timer_tb, cpu) >= wd_panic_timeout_tb) {
	248	per_cpu(wd_timer_tb, cpu) = tb;
	249
	250	wd_smp_lock(&flags);
	251	if (cpumask_test_cpu(cpu, &wd_smp_cpus_stuck)) {
	252	wd_smp_unlock(&flags);
	253	goto out;
	254	}
	255	set_cpu_stuck(cpu, tb);
	256
0bc00914	257	pr_emerg("CPU %d self-detected hard LOCKUP @ %pS\n", cpu, (void *)regs->nip);
2104180a NP	258	print_modules();
2104180a NP	259	print_irqtrace_events(current);
3ba45b7e	260	show_regs(regs);
2104180a NP	261
	262	wd_smp_unlock(&flags);
	263
	264	if (sysctl_hardlockup_all_cpu_backtrace)
	265	trigger_allbutself_cpu_backtrace();
	266
	267	if (hardlockup_panic)
	268	nmi_panic(regs, "Hard LOCKUP");
	269	}
	270	if (wd_panic_timeout_tb < 0x7fffffff)
	271	mtspr(SPRN_DEC, wd_panic_timeout_tb);
	272
	273	out:
	274	nmi_exit();
	275	}
	276
	277	static void wd_timer_reset(unsigned int cpu, struct timer_list *t)
	278	{
	279	t->expires = jiffies + msecs_to_jiffies(wd_timer_period_ms);
	280	if (wd_timer_period_ms > 1000)
	281	t->expires = __round_jiffies_up(t->expires, cpu);
	282	add_timer_on(t, cpu);
	283	}
	284
5943cf4a	285	static void wd_timer_fn(struct timer_list *t)
2104180a	286	{
2104180a NP	287	int cpu = smp_processor_id();
	288
	289	watchdog_timer_interrupt(cpu);
	290
	291	wd_timer_reset(cpu, t);
	292	}
	293
	294	void arch_touch_nmi_watchdog(void)
	295	{
26c5c6e1	296	unsigned long ticks = tb_ticks_per_usec * wd_timer_period_ms * 1000;
2104180a	297	int cpu = smp_processor_id();
80e4d70b	298	u64 tb = get_tb();
2104180a	299
80e4d70b NP	300	if (tb - per_cpu(wd_timer_tb, cpu) >= ticks) {
	301	per_cpu(wd_timer_tb, cpu) = tb;
	302	wd_smp_clear_cpu_pending(cpu, tb);
	303	}
2104180a NP	304	}
	305	EXPORT_SYMBOL(arch_touch_nmi_watchdog);
	306
	307	static void start_watchdog_timer_on(unsigned int cpu)
	308	{
	309	struct timer_list *t = per_cpu_ptr(&wd_timer, cpu);
	310
	311	per_cpu(wd_timer_tb, cpu) = get_tb();
	312
5943cf4a	313	timer_setup(t, wd_timer_fn, TIMER_PINNED);
2104180a NP	314	wd_timer_reset(cpu, t);
	315	}
	316
	317	static void stop_watchdog_timer_on(unsigned int cpu)
	318	{
	319	struct timer_list *t = per_cpu_ptr(&wd_timer, cpu);
	320
	321	del_timer_sync(t);
	322	}
	323
	324	static int start_wd_on_cpu(unsigned int cpu)
	325	{
96ea91e7 NP	326	unsigned long flags;
96ea91e7 NP	327
2104180a NP	328	if (cpumask_test_cpu(cpu, &wd_cpus_enabled)) {
	329	WARN_ON(1);
	330	return 0;
	331	}
	332
	333	if (!(watchdog_enabled & NMI_WATCHDOG_ENABLED))
	334	return 0;
	335
2104180a NP	336	if (!cpumask_test_cpu(cpu, &watchdog_cpumask))
	337	return 0;
	338
96ea91e7	339	wd_smp_lock(&flags);
2104180a NP	340	cpumask_set_cpu(cpu, &wd_cpus_enabled);
	341	if (cpumask_weight(&wd_cpus_enabled) == 1) {
	342	cpumask_set_cpu(cpu, &wd_smp_cpus_pending);
	343	wd_smp_last_reset_tb = get_tb();
	344	}
96ea91e7 NP	345	wd_smp_unlock(&flags);
96ea91e7 NP	346
2104180a NP	347	start_watchdog_timer_on(cpu);
	348
	349	return 0;
	350	}
	351
	352	static int stop_wd_on_cpu(unsigned int cpu)
	353	{
96ea91e7 NP	354	unsigned long flags;
96ea91e7 NP	355
2104180a NP	356	if (!cpumask_test_cpu(cpu, &wd_cpus_enabled))
	357	return 0; /* Can happen in CPU unplug case */
	358
	359	stop_watchdog_timer_on(cpu);
	360
96ea91e7	361	wd_smp_lock(&flags);
2104180a	362	cpumask_clear_cpu(cpu, &wd_cpus_enabled);
96ea91e7 NP	363	wd_smp_unlock(&flags);
96ea91e7 NP	364
2104180a NP	365	wd_smp_clear_cpu_pending(cpu, get_tb());
	366
	367	return 0;
	368	}
	369
	370	static void watchdog_calc_timeouts(void)
	371	{
	372	wd_panic_timeout_tb = watchdog_thresh * ppc_tb_freq;
	373
	374	/* Have the SMP detector trigger a bit later */
	375	wd_smp_panic_timeout_tb = wd_panic_timeout_tb * 3 / 2;
	376
	377	/* 2/5 is the factor that the perf based detector uses */
	378	wd_timer_period_ms = watchdog_thresh * 1000 * 2 / 5;
	379	}
	380
6b9dc480	381	void watchdog_nmi_stop(void)
2104180a NP	382	{
	383	int cpu;
	384
6b9dc480 TG	385	for_each_cpu(cpu, &wd_cpus_enabled)
6b9dc480 TG	386	stop_wd_on_cpu(cpu);
6b9dc480 TG	387	}
	388
	389	void watchdog_nmi_start(void)
	390	{
	391	int cpu;
	392
6b9dc480 TG	393	watchdog_calc_timeouts();
	394	for_each_cpu_and(cpu, cpu_online_mask, &watchdog_cpumask)
	395	start_wd_on_cpu(cpu);
2104180a NP	396	}
	397
	398	/*
34ddaa3e	399	* Invoked from core watchdog init.
2104180a	400	*/
34ddaa3e	401	int __init watchdog_nmi_probe(void)
2104180a NP	402	{
	403	int err;
	404
34ddaa3e TG	405	err = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
	406	"powerpc/watchdog:online",
	407	start_wd_on_cpu, stop_wd_on_cpu);
	408	if (err < 0) {
d8fa82e0	409	pr_warn("could not be initialized");
34ddaa3e TG	410	return err;
34ddaa3e TG	411	}
2104180a NP	412	return 0;
2104180a NP	413	}