xref: /linux/arch/sparc/kernel/nmi.c (revision 79790b6818e96c58fe2bffee1b418c16e64e7b80)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Pseudo NMI support on sparc64 systems.
3  *
4  * Copyright (C) 2009 David S. Miller <davem@davemloft.net>
5  *
6  * The NMI watchdog support and infrastructure is based almost
7  * entirely upon the x86 NMI support code.
8  */
9 #include <linux/kernel.h>
10 #include <linux/param.h>
11 #include <linux/init.h>
12 #include <linux/percpu.h>
13 #include <linux/nmi.h>
14 #include <linux/export.h>
15 #include <linux/kprobes.h>
16 #include <linux/kernel_stat.h>
17 #include <linux/reboot.h>
18 #include <linux/slab.h>
19 #include <linux/kdebug.h>
20 #include <linux/delay.h>
21 #include <linux/smp.h>
22 
23 #include <asm/perf_event.h>
24 #include <asm/ptrace.h>
25 #include <asm/pcr.h>
26 
27 #include "kstack.h"
28 
29 /* We don't have a real NMI on sparc64, but we can fake one
30  * up using profiling counter overflow interrupts and interrupt
31  * levels.
32  *
33  * The profile overflow interrupts at level 15, so we use
34  * level 14 as our IRQ off level.
35  */
36 
37 static int panic_on_timeout;
38 
39 /* nmi_active:
40  * >0: the NMI watchdog is active, but can be disabled
41  * <0: the NMI watchdog has not been set up, and cannot be enabled
42  *  0: the NMI watchdog is disabled, but can be enabled
43  */
44 atomic_t nmi_active = ATOMIC_INIT(0);		/* oprofile uses this */
45 EXPORT_SYMBOL(nmi_active);
46 static int nmi_init_done;
47 static unsigned int nmi_hz = HZ;
48 static DEFINE_PER_CPU(short, wd_enabled);
49 static int endflag __initdata;
50 
51 static DEFINE_PER_CPU(unsigned int, last_irq_sum);
52 static DEFINE_PER_CPU(long, alert_counter);
53 static DEFINE_PER_CPU(int, nmi_touch);
54 
arch_touch_nmi_watchdog(void)55 void arch_touch_nmi_watchdog(void)
56 {
57 	if (atomic_read(&nmi_active)) {
58 		int cpu;
59 
60 		for_each_present_cpu(cpu) {
61 			if (per_cpu(nmi_touch, cpu) != 1)
62 				per_cpu(nmi_touch, cpu) = 1;
63 		}
64 	}
65 }
66 EXPORT_SYMBOL(arch_touch_nmi_watchdog);
67 
watchdog_hardlockup_probe(void)68 int __init watchdog_hardlockup_probe(void)
69 {
70 	return 0;
71 }
72 
die_nmi(const char * str,struct pt_regs * regs,int do_panic)73 static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
74 {
75 	int this_cpu = smp_processor_id();
76 
77 	if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
78 		       pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
79 		return;
80 
81 	if (do_panic || panic_on_oops)
82 		panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
83 	else
84 		WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu);
85 }
86 
perfctr_irq(int irq,struct pt_regs * regs)87 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
88 {
89 	unsigned int sum, touched = 0;
90 	void *orig_sp;
91 
92 	clear_softint(1 << irq);
93 
94 	local_cpu_data().__nmi_count++;
95 
96 	nmi_enter();
97 
98 	orig_sp = set_hardirq_stack();
99 
100 	if (notify_die(DIE_NMI, "nmi", regs, 0,
101 		       pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
102 		touched = 1;
103 	else
104 		pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
105 
106 	sum = local_cpu_data().irq0_irqs;
107 	if (__this_cpu_read(nmi_touch)) {
108 		__this_cpu_write(nmi_touch, 0);
109 		touched = 1;
110 	}
111 	if (!touched && __this_cpu_read(last_irq_sum) == sum) {
112 		__this_cpu_inc(alert_counter);
113 		if (__this_cpu_read(alert_counter) == 30 * nmi_hz)
114 			die_nmi("BUG: NMI Watchdog detected LOCKUP",
115 				regs, panic_on_timeout);
116 	} else {
117 		__this_cpu_write(last_irq_sum, sum);
118 		__this_cpu_write(alert_counter, 0);
119 	}
120 	if (__this_cpu_read(wd_enabled)) {
121 		pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
122 		pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
123 	}
124 
125 	restore_hardirq_stack(orig_sp);
126 
127 	nmi_exit();
128 }
129 
get_nmi_count(int cpu)130 static inline unsigned int get_nmi_count(int cpu)
131 {
132 	return cpu_data(cpu).__nmi_count;
133 }
134 
nmi_cpu_busy(void * data)135 static __init void nmi_cpu_busy(void *data)
136 {
137 	while (endflag == 0)
138 		mb();
139 }
140 
report_broken_nmi(int cpu,int * prev_nmi_count)141 static void report_broken_nmi(int cpu, int *prev_nmi_count)
142 {
143 	printk(KERN_CONT "\n");
144 
145 	printk(KERN_WARNING
146 		"WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
147 			cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
148 
149 	printk(KERN_WARNING
150 		"Please report this to bugzilla.kernel.org,\n");
151 	printk(KERN_WARNING
152 		"and attach the output of the 'dmesg' command.\n");
153 
154 	per_cpu(wd_enabled, cpu) = 0;
155 	atomic_dec(&nmi_active);
156 }
157 
stop_nmi_watchdog(void * unused)158 void stop_nmi_watchdog(void *unused)
159 {
160 	if (!__this_cpu_read(wd_enabled))
161 		return;
162 	pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
163 	__this_cpu_write(wd_enabled, 0);
164 	atomic_dec(&nmi_active);
165 }
166 
check_nmi_watchdog(void)167 static int __init check_nmi_watchdog(void)
168 {
169 	unsigned int *prev_nmi_count;
170 	int cpu, err;
171 
172 	if (!atomic_read(&nmi_active))
173 		return 0;
174 
175 	prev_nmi_count = kmalloc_array(nr_cpu_ids, sizeof(unsigned int),
176 				       GFP_KERNEL);
177 	if (!prev_nmi_count) {
178 		err = -ENOMEM;
179 		goto error;
180 	}
181 
182 	printk(KERN_INFO "Testing NMI watchdog ... ");
183 
184 	smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
185 
186 	for_each_possible_cpu(cpu)
187 		prev_nmi_count[cpu] = get_nmi_count(cpu);
188 	local_irq_enable();
189 	mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
190 
191 	for_each_online_cpu(cpu) {
192 		if (!per_cpu(wd_enabled, cpu))
193 			continue;
194 		if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
195 			report_broken_nmi(cpu, prev_nmi_count);
196 	}
197 	endflag = 1;
198 	if (!atomic_read(&nmi_active)) {
199 		kfree(prev_nmi_count);
200 		atomic_set(&nmi_active, -1);
201 		err = -ENODEV;
202 		goto error;
203 	}
204 	printk("OK.\n");
205 
206 	nmi_hz = 1;
207 
208 	kfree(prev_nmi_count);
209 	return 0;
210 error:
211 	on_each_cpu(stop_nmi_watchdog, NULL, 1);
212 	return err;
213 }
214 
start_nmi_watchdog(void * unused)215 void start_nmi_watchdog(void *unused)
216 {
217 	if (__this_cpu_read(wd_enabled))
218 		return;
219 
220 	__this_cpu_write(wd_enabled, 1);
221 	atomic_inc(&nmi_active);
222 
223 	pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
224 	pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
225 
226 	pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
227 }
228 
nmi_adjust_hz_one(void * unused)229 static void nmi_adjust_hz_one(void *unused)
230 {
231 	if (!__this_cpu_read(wd_enabled))
232 		return;
233 
234 	pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
235 	pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
236 
237 	pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
238 }
239 
nmi_adjust_hz(unsigned int new_hz)240 void nmi_adjust_hz(unsigned int new_hz)
241 {
242 	nmi_hz = new_hz;
243 	on_each_cpu(nmi_adjust_hz_one, NULL, 1);
244 }
245 EXPORT_SYMBOL_GPL(nmi_adjust_hz);
246 
nmi_shutdown(struct notifier_block * nb,unsigned long cmd,void * p)247 static int nmi_shutdown(struct notifier_block *nb, unsigned long cmd, void *p)
248 {
249 	on_each_cpu(stop_nmi_watchdog, NULL, 1);
250 	return 0;
251 }
252 
253 static struct notifier_block nmi_reboot_notifier = {
254 	.notifier_call = nmi_shutdown,
255 };
256 
nmi_init(void)257 int __init nmi_init(void)
258 {
259 	int err;
260 
261 	on_each_cpu(start_nmi_watchdog, NULL, 1);
262 
263 	err = check_nmi_watchdog();
264 	if (!err) {
265 		err = register_reboot_notifier(&nmi_reboot_notifier);
266 		if (err) {
267 			on_each_cpu(stop_nmi_watchdog, NULL, 1);
268 			atomic_set(&nmi_active, -1);
269 		}
270 	}
271 
272 	nmi_init_done = 1;
273 
274 	return err;
275 }
276 
setup_nmi_watchdog(char * str)277 static int __init setup_nmi_watchdog(char *str)
278 {
279 	if (!strncmp(str, "panic", 5))
280 		panic_on_timeout = 1;
281 
282 	return 1;
283 }
284 __setup("nmi_watchdog=", setup_nmi_watchdog);
285 
286 /*
287  * sparc specific NMI watchdog enable function.
288  * Enables watchdog if it is not enabled already.
289  */
watchdog_hardlockup_enable(unsigned int cpu)290 void watchdog_hardlockup_enable(unsigned int cpu)
291 {
292 	if (atomic_read(&nmi_active) == -1) {
293 		pr_warn("NMI watchdog cannot be enabled or disabled\n");
294 		return;
295 	}
296 
297 	/*
298 	 * watchdog thread could start even before nmi_init is called.
299 	 * Just Return in that case. Let nmi_init finish the init
300 	 * process first.
301 	 */
302 	if (!nmi_init_done)
303 		return;
304 
305 	smp_call_function_single(cpu, start_nmi_watchdog, NULL, 1);
306 }
307 /*
308  * sparc specific NMI watchdog disable function.
309  * Disables watchdog if it is not disabled already.
310  */
watchdog_hardlockup_disable(unsigned int cpu)311 void watchdog_hardlockup_disable(unsigned int cpu)
312 {
313 	if (atomic_read(&nmi_active) == -1)
314 		pr_warn_once("NMI watchdog cannot be enabled or disabled\n");
315 	else
316 		smp_call_function_single(cpu, stop_nmi_watchdog, NULL, 1);
317 }
318