Merge branch 'linus' into sched/core
[linux-3.10.git] / arch / sparc / kernel / nmi.c
1 /* Pseudo NMI support on sparc64 systems.
2  *
3  * Copyright (C) 2009 David S. Miller <davem@davemloft.net>
4  *
5  * The NMI watchdog support and infrastructure is based almost
6  * entirely upon the x86 NMI support code.
7  */
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/module.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 /* We don't have a real NMI on sparc64, but we can fake one
27  * up using profiling counter overflow interrupts and interrupt
28  * levels.
29  *
30  * The profile overflow interrupts at level 15, so we use
31  * level 14 as our IRQ off level.
32  */
33
34 static int panic_on_timeout;
35
36 /* nmi_active:
37  * >0: the NMI watchdog is active, but can be disabled
38  * <0: the NMI watchdog has not been set up, and cannot be enabled
39  *  0: the NMI watchdog is disabled, but can be enabled
40  */
41 atomic_t nmi_active = ATOMIC_INIT(0);           /* oprofile uses this */
42 EXPORT_SYMBOL(nmi_active);
43
44 static unsigned int nmi_hz = HZ;
45 static DEFINE_PER_CPU(short, wd_enabled);
46 static int endflag __initdata;
47
48 static DEFINE_PER_CPU(unsigned int, last_irq_sum);
49 static DEFINE_PER_CPU(long, alert_counter);
50 static DEFINE_PER_CPU(int, nmi_touch);
51
52 void touch_nmi_watchdog(void)
53 {
54         if (atomic_read(&nmi_active)) {
55                 int cpu;
56
57                 for_each_present_cpu(cpu) {
58                         if (per_cpu(nmi_touch, cpu) != 1)
59                                 per_cpu(nmi_touch, cpu) = 1;
60                 }
61         }
62
63         touch_softlockup_watchdog();
64 }
65 EXPORT_SYMBOL(touch_nmi_watchdog);
66
67 static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
68 {
69         if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
70                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
71                 return;
72
73         console_verbose();
74         bust_spinlocks(1);
75
76         printk(KERN_EMERG "%s", str);
77         printk(" on CPU%d, ip %08lx, registers:\n",
78                smp_processor_id(), regs->tpc);
79         show_regs(regs);
80         dump_stack();
81
82         bust_spinlocks(0);
83
84         if (do_panic || panic_on_oops)
85                 panic("Non maskable interrupt");
86
87         nmi_exit();
88         local_irq_enable();
89         do_exit(SIGBUS);
90 }
91
92 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
93 {
94         unsigned int sum, touched = 0;
95
96         clear_softint(1 << irq);
97
98         local_cpu_data().__nmi_count++;
99
100         nmi_enter();
101
102         if (notify_die(DIE_NMI, "nmi", regs, 0,
103                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
104                 touched = 1;
105         else
106                 pcr_ops->write(PCR_PIC_PRIV);
107
108         sum = local_cpu_data().irq0_irqs;
109         if (__get_cpu_var(nmi_touch)) {
110                 __get_cpu_var(nmi_touch) = 0;
111                 touched = 1;
112         }
113         if (!touched && __get_cpu_var(last_irq_sum) == sum) {
114                 __this_cpu_inc(alert_counter);
115                 if (__this_cpu_read(alert_counter) == 30 * nmi_hz)
116                         die_nmi("BUG: NMI Watchdog detected LOCKUP",
117                                 regs, panic_on_timeout);
118         } else {
119                 __get_cpu_var(last_irq_sum) = sum;
120                 __this_cpu_write(alert_counter, 0);
121         }
122         if (__get_cpu_var(wd_enabled)) {
123                 write_pic(picl_value(nmi_hz));
124                 pcr_ops->write(pcr_enable);
125         }
126
127         nmi_exit();
128 }
129
130 static inline unsigned int get_nmi_count(int cpu)
131 {
132         return cpu_data(cpu).__nmi_count;
133 }
134
135 static __init void nmi_cpu_busy(void *data)
136 {
137         local_irq_enable_in_hardirq();
138         while (endflag == 0)
139                 mb();
140 }
141
142 static void report_broken_nmi(int cpu, int *prev_nmi_count)
143 {
144         printk(KERN_CONT "\n");
145
146         printk(KERN_WARNING
147                 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
148                         cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
149
150         printk(KERN_WARNING
151                 "Please report this to bugzilla.kernel.org,\n");
152         printk(KERN_WARNING
153                 "and attach the output of the 'dmesg' command.\n");
154
155         per_cpu(wd_enabled, cpu) = 0;
156         atomic_dec(&nmi_active);
157 }
158
159 void stop_nmi_watchdog(void *unused)
160 {
161         pcr_ops->write(PCR_PIC_PRIV);
162         __get_cpu_var(wd_enabled) = 0;
163         atomic_dec(&nmi_active);
164 }
165
166 static int __init check_nmi_watchdog(void)
167 {
168         unsigned int *prev_nmi_count;
169         int cpu, err;
170
171         if (!atomic_read(&nmi_active))
172                 return 0;
173
174         prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
175         if (!prev_nmi_count) {
176                 err = -ENOMEM;
177                 goto error;
178         }
179
180         printk(KERN_INFO "Testing NMI watchdog ... ");
181
182         smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
183
184         for_each_possible_cpu(cpu)
185                 prev_nmi_count[cpu] = get_nmi_count(cpu);
186         local_irq_enable();
187         mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
188
189         for_each_online_cpu(cpu) {
190                 if (!per_cpu(wd_enabled, cpu))
191                         continue;
192                 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
193                         report_broken_nmi(cpu, prev_nmi_count);
194         }
195         endflag = 1;
196         if (!atomic_read(&nmi_active)) {
197                 kfree(prev_nmi_count);
198                 atomic_set(&nmi_active, -1);
199                 err = -ENODEV;
200                 goto error;
201         }
202         printk("OK.\n");
203
204         nmi_hz = 1;
205
206         kfree(prev_nmi_count);
207         return 0;
208 error:
209         on_each_cpu(stop_nmi_watchdog, NULL, 1);
210         return err;
211 }
212
213 void start_nmi_watchdog(void *unused)
214 {
215         __get_cpu_var(wd_enabled) = 1;
216         atomic_inc(&nmi_active);
217
218         pcr_ops->write(PCR_PIC_PRIV);
219         write_pic(picl_value(nmi_hz));
220
221         pcr_ops->write(pcr_enable);
222 }
223
224 static void nmi_adjust_hz_one(void *unused)
225 {
226         if (!__get_cpu_var(wd_enabled))
227                 return;
228
229         pcr_ops->write(PCR_PIC_PRIV);
230         write_pic(picl_value(nmi_hz));
231
232         pcr_ops->write(pcr_enable);
233 }
234
235 void nmi_adjust_hz(unsigned int new_hz)
236 {
237         nmi_hz = new_hz;
238         on_each_cpu(nmi_adjust_hz_one, NULL, 1);
239 }
240 EXPORT_SYMBOL_GPL(nmi_adjust_hz);
241
242 static int nmi_shutdown(struct notifier_block *nb, unsigned long cmd, void *p)
243 {
244         on_each_cpu(stop_nmi_watchdog, NULL, 1);
245         return 0;
246 }
247
248 static struct notifier_block nmi_reboot_notifier = {
249         .notifier_call = nmi_shutdown,
250 };
251
252 int __init nmi_init(void)
253 {
254         int err;
255
256         on_each_cpu(start_nmi_watchdog, NULL, 1);
257
258         err = check_nmi_watchdog();
259         if (!err) {
260                 err = register_reboot_notifier(&nmi_reboot_notifier);
261                 if (err) {
262                         on_each_cpu(stop_nmi_watchdog, NULL, 1);
263                         atomic_set(&nmi_active, -1);
264                 }
265         }
266         if (!err)
267                 init_hw_perf_events();
268
269         return err;
270 }
271
272 static int __init setup_nmi_watchdog(char *str)
273 {
274         if (!strncmp(str, "panic", 5))
275                 panic_on_timeout = 1;
276
277         return 0;
278 }
279 __setup("nmi_watchdog=", setup_nmi_watchdog);