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

/*
 * Watchdog support on powerpc systems.
 *
 * Copyright 2017, IBM Corporation.
 *
 * This uses code from arch/sparc/kernel/nmi.c and kernel/watchdog.c
 */
#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 watchdog has a simple timer that runs on each CPU, once per timer
 * period. This is the heartbeat.
 *
 * Then there are checks to see if the heartbeat has not triggered on a CPU
 * for the panic timeout period. Currently the watchdog only supports an
 * SMP check, so the heartbeat only turns on when we have 2 or more CPUs.
 *
 * This is not an NMI watchdog, but Linux uses that name for a generic
 * watchdog in some cases, so NMI gets used in some places.
 */

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);

/*
 * These are for the SMP checker. CPUs clear their pending bit in their
 * heartbeat. If the bitmask becomes empty, the time is noted and the
 * bitmask is refilled.
 *
 * All CPUs clear their bit in the pending mask every timer period.
 * Once all have cleared, the time is noted and the bits are reset.
 * If the time since all clear was greater than the panic timeout,
 * we can panic with the list of stuck CPUs.
 *
 * This will work best with NMI IPIs for crash code so the stuck CPUs
 * can be pulled out to get their backtraces.
 */
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("Watchdog CPU:%d Hard LOCKUP\n", raw_smp_processor_id());
	print_modules();
	print_irqtrace_events(current);
	if (regs)
		show_regs(regs);
	else
		dump_stack();

	if (hardlockup_panic)
		nmi_panic(regs, "Hard LOCKUP");
}

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("Watchdog CPU:%d detected Hard LOCKUP other CPUS:%*pbl\n",
			cpu, cpumask_pr_args(&wd_smp_cpus_pending));

	/*
	 * Try to trigger the stuck CPUs.
	 */
	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("Watchdog 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("Watchdog CPU:%d Hard LOCKUP\n", cpu);
		print_modules();
		print_irqtrace_events(current);
		if (regs)
			show_regs(regs);
		else
			dump_stack();

		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(unsigned long data)
{
	struct timer_list *t = this_cpu_ptr(&wd_timer);
	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();

	if (get_tb() - per_cpu(wd_timer_tb, cpu) >= ticks)
		watchdog_timer_interrupt(cpu);
}
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();

	setup_pinned_timer(t, wd_timer_fn, 0);
	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);
}

/*
 * This runs after lockup_detector_init() which sets up watchdog_cpumask.
 */
static int __init powerpc_watchdog_init(void)
{
	int err;

	watchdog_calc_timeouts();

	err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "powerpc/watchdog:online",
				start_wd_on_cpu, stop_wd_on_cpu);
	if (err < 0)
		pr_warn("Watchdog could not be initialized");

	return 0;
}
arch_initcall(powerpc_watchdog_init);

static void handle_backtrace_ipi(struct pt_regs *regs)
{
	nmi_cpu_backtrace(regs);
}

static void raise_backtrace_ipi(cpumask_t *mask)
{
	unsigned int cpu;

	for_each_cpu(cpu, mask) {
		if (cpu == smp_processor_id())
			handle_backtrace_ipi(NULL);
		else
			smp_send_nmi_ipi(cpu, handle_backtrace_ipi, 1000000);
	}
}

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