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8#include <linux/kernel.h>
9#include <linux/param.h>
10#include <linux/init.h>
11#include <linux/percpu.h>
12#include <linux/nmi.h>
13#include <linux/export.h>
14#include <linux/kprobes.h>
15#include <linux/kernel_stat.h>
16#include <linux/reboot.h>
17#include <linux/slab.h>
18#include <linux/kdebug.h>
19#include <linux/delay.h>
20#include <linux/smp.h>
21
22#include <asm/perf_event.h>
23#include <asm/ptrace.h>
24#include <asm/pcr.h>
25
26#include "kstack.h"
27
28
29
30
31
32
33
34
35
36static int panic_on_timeout;
37
38
39
40
41
42
43atomic_t nmi_active = ATOMIC_INIT(0);
44EXPORT_SYMBOL(nmi_active);
45
46static unsigned int nmi_hz = HZ;
47static DEFINE_PER_CPU(short, wd_enabled);
48static int endflag __initdata;
49
50static DEFINE_PER_CPU(unsigned int, last_irq_sum);
51static DEFINE_PER_CPU(long, alert_counter);
52static DEFINE_PER_CPU(int, nmi_touch);
53
54void touch_nmi_watchdog(void)
55{
56 if (atomic_read(&nmi_active)) {
57 int cpu;
58
59 for_each_present_cpu(cpu) {
60 if (per_cpu(nmi_touch, cpu) != 1)
61 per_cpu(nmi_touch, cpu) = 1;
62 }
63 }
64
65 touch_softlockup_watchdog();
66}
67EXPORT_SYMBOL(touch_nmi_watchdog);
68
69static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
70{
71 if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
72 pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
73 return;
74
75 console_verbose();
76 bust_spinlocks(1);
77
78 printk(KERN_EMERG "%s", str);
79 printk(" on CPU%d, ip %08lx, registers:\n",
80 smp_processor_id(), regs->tpc);
81 show_regs(regs);
82 dump_stack();
83
84 bust_spinlocks(0);
85
86 if (do_panic || panic_on_oops)
87 panic("Non maskable interrupt");
88
89 nmi_exit();
90 local_irq_enable();
91 do_exit(SIGBUS);
92}
93
94notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
95{
96 unsigned int sum, touched = 0;
97 void *orig_sp;
98
99 clear_softint(1 << irq);
100
101 local_cpu_data().__nmi_count++;
102
103 nmi_enter();
104
105 orig_sp = set_hardirq_stack();
106
107 if (notify_die(DIE_NMI, "nmi", regs, 0,
108 pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
109 touched = 1;
110 else
111 pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
112
113 sum = local_cpu_data().irq0_irqs;
114 if (__get_cpu_var(nmi_touch)) {
115 __get_cpu_var(nmi_touch) = 0;
116 touched = 1;
117 }
118 if (!touched && __get_cpu_var(last_irq_sum) == sum) {
119 __this_cpu_inc(alert_counter);
120 if (__this_cpu_read(alert_counter) == 30 * nmi_hz)
121 die_nmi("BUG: NMI Watchdog detected LOCKUP",
122 regs, panic_on_timeout);
123 } else {
124 __get_cpu_var(last_irq_sum) = sum;
125 __this_cpu_write(alert_counter, 0);
126 }
127 if (__get_cpu_var(wd_enabled)) {
128 pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
129 pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
130 }
131
132 restore_hardirq_stack(orig_sp);
133
134 nmi_exit();
135}
136
137static inline unsigned int get_nmi_count(int cpu)
138{
139 return cpu_data(cpu).__nmi_count;
140}
141
142static __init void nmi_cpu_busy(void *data)
143{
144 local_irq_enable_in_hardirq();
145 while (endflag == 0)
146 mb();
147}
148
149static void report_broken_nmi(int cpu, int *prev_nmi_count)
150{
151 printk(KERN_CONT "\n");
152
153 printk(KERN_WARNING
154 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
155 cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
156
157 printk(KERN_WARNING
158 "Please report this to bugzilla.kernel.org,\n");
159 printk(KERN_WARNING
160 "and attach the output of the 'dmesg' command.\n");
161
162 per_cpu(wd_enabled, cpu) = 0;
163 atomic_dec(&nmi_active);
164}
165
166void stop_nmi_watchdog(void *unused)
167{
168 pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
169 __get_cpu_var(wd_enabled) = 0;
170 atomic_dec(&nmi_active);
171}
172
173static int __init check_nmi_watchdog(void)
174{
175 unsigned int *prev_nmi_count;
176 int cpu, err;
177
178 if (!atomic_read(&nmi_active))
179 return 0;
180
181 prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
182 if (!prev_nmi_count) {
183 err = -ENOMEM;
184 goto error;
185 }
186
187 printk(KERN_INFO "Testing NMI watchdog ... ");
188
189 smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
190
191 for_each_possible_cpu(cpu)
192 prev_nmi_count[cpu] = get_nmi_count(cpu);
193 local_irq_enable();
194 mdelay((20 * 1000) / nmi_hz);
195
196 for_each_online_cpu(cpu) {
197 if (!per_cpu(wd_enabled, cpu))
198 continue;
199 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
200 report_broken_nmi(cpu, prev_nmi_count);
201 }
202 endflag = 1;
203 if (!atomic_read(&nmi_active)) {
204 kfree(prev_nmi_count);
205 atomic_set(&nmi_active, -1);
206 err = -ENODEV;
207 goto error;
208 }
209 printk("OK.\n");
210
211 nmi_hz = 1;
212
213 kfree(prev_nmi_count);
214 return 0;
215error:
216 on_each_cpu(stop_nmi_watchdog, NULL, 1);
217 return err;
218}
219
220void start_nmi_watchdog(void *unused)
221{
222 __get_cpu_var(wd_enabled) = 1;
223 atomic_inc(&nmi_active);
224
225 pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
226 pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
227
228 pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
229}
230
231static void nmi_adjust_hz_one(void *unused)
232{
233 if (!__get_cpu_var(wd_enabled))
234 return;
235
236 pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
237 pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
238
239 pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
240}
241
242void nmi_adjust_hz(unsigned int new_hz)
243{
244 nmi_hz = new_hz;
245 on_each_cpu(nmi_adjust_hz_one, NULL, 1);
246}
247EXPORT_SYMBOL_GPL(nmi_adjust_hz);
248
249static int nmi_shutdown(struct notifier_block *nb, unsigned long cmd, void *p)
250{
251 on_each_cpu(stop_nmi_watchdog, NULL, 1);
252 return 0;
253}
254
255static struct notifier_block nmi_reboot_notifier = {
256 .notifier_call = nmi_shutdown,
257};
258
259int __init nmi_init(void)
260{
261 int err;
262
263 on_each_cpu(start_nmi_watchdog, NULL, 1);
264
265 err = check_nmi_watchdog();
266 if (!err) {
267 err = register_reboot_notifier(&nmi_reboot_notifier);
268 if (err) {
269 on_each_cpu(stop_nmi_watchdog, NULL, 1);
270 atomic_set(&nmi_active, -1);
271 }
272 }
273
274 return err;
275}
276
277static int __init setup_nmi_watchdog(char *str)
278{
279 if (!strncmp(str, "panic", 5))
280 panic_on_timeout = 1;
281
282 return 0;
283}
284__setup("nmi_watchdog=", setup_nmi_watchdog);
285
