Merge branch 'linux-next' of git://git.infradead.org/ubi-2.6
[linux-2.6] / 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/ptrace.h>
23 #include <asm/local.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 nmi_watchdog_active;
35 static int panic_on_timeout;
36
37 int nmi_usable;
38 EXPORT_SYMBOL_GPL(nmi_usable);
39
40 static unsigned int nmi_hz = HZ;
41
42 static DEFINE_PER_CPU(unsigned int, last_irq_sum);
43 static DEFINE_PER_CPU(local_t, alert_counter);
44 static DEFINE_PER_CPU(int, nmi_touch);
45
46 void touch_nmi_watchdog(void)
47 {
48         if (nmi_watchdog_active) {
49                 int cpu;
50
51                 for_each_present_cpu(cpu) {
52                         if (per_cpu(nmi_touch, cpu) != 1)
53                                 per_cpu(nmi_touch, cpu) = 1;
54                 }
55         }
56
57         touch_softlockup_watchdog();
58 }
59 EXPORT_SYMBOL(touch_nmi_watchdog);
60
61 static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
62 {
63         if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
64                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
65                 return;
66
67         console_verbose();
68         bust_spinlocks(1);
69
70         printk(KERN_EMERG "%s", str);
71         printk(" on CPU%d, ip %08lx, registers:\n",
72                smp_processor_id(), regs->tpc);
73         show_regs(regs);
74         dump_stack();
75
76         bust_spinlocks(0);
77
78         if (do_panic || panic_on_oops)
79                 panic("Non maskable interrupt");
80
81         local_irq_enable();
82         do_exit(SIGBUS);
83 }
84
85 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
86 {
87         unsigned int sum, touched = 0;
88         int cpu = smp_processor_id();
89
90         clear_softint(1 << irq);
91         pcr_ops->write(PCR_PIC_PRIV);
92
93         local_cpu_data().__nmi_count++;
94
95         if (notify_die(DIE_NMI, "nmi", regs, 0,
96                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
97                 touched = 1;
98
99         sum = kstat_irqs_cpu(0, cpu);
100         if (__get_cpu_var(nmi_touch)) {
101                 __get_cpu_var(nmi_touch) = 0;
102                 touched = 1;
103         }
104         if (!touched && __get_cpu_var(last_irq_sum) == sum) {
105                 local_inc(&__get_cpu_var(alert_counter));
106                 if (local_read(&__get_cpu_var(alert_counter)) == 5 * nmi_hz)
107                         die_nmi("BUG: NMI Watchdog detected LOCKUP",
108                                 regs, panic_on_timeout);
109         } else {
110                 __get_cpu_var(last_irq_sum) = sum;
111                 local_set(&__get_cpu_var(alert_counter), 0);
112         }
113         if (nmi_usable) {
114                 write_pic(picl_value(nmi_hz));
115                 pcr_ops->write(pcr_enable);
116         }
117 }
118
119 static inline unsigned int get_nmi_count(int cpu)
120 {
121         return cpu_data(cpu).__nmi_count;
122 }
123
124 static int endflag __initdata;
125
126 static __init void nmi_cpu_busy(void *data)
127 {
128         local_irq_enable_in_hardirq();
129         while (endflag == 0)
130                 mb();
131 }
132
133 static void report_broken_nmi(int cpu, int *prev_nmi_count)
134 {
135         printk(KERN_CONT "\n");
136
137         printk(KERN_WARNING
138                 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
139                         cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
140
141         printk(KERN_WARNING
142                 "Please report this to bugzilla.kernel.org,\n");
143         printk(KERN_WARNING
144                 "and attach the output of the 'dmesg' command.\n");
145
146         nmi_usable = 0;
147 }
148
149 static void stop_watchdog(void *unused)
150 {
151         pcr_ops->write(PCR_PIC_PRIV);
152 }
153
154 static int __init check_nmi_watchdog(void)
155 {
156         unsigned int *prev_nmi_count;
157         int cpu, err;
158
159         prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
160         if (!prev_nmi_count) {
161                 err = -ENOMEM;
162                 goto error;
163         }
164
165         printk(KERN_INFO "Testing NMI watchdog ... ");
166
167         smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
168
169         for_each_possible_cpu(cpu)
170                 prev_nmi_count[cpu] = get_nmi_count(cpu);
171         local_irq_enable();
172         mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
173
174         for_each_online_cpu(cpu) {
175                 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
176                         report_broken_nmi(cpu, prev_nmi_count);
177         }
178         endflag = 1;
179         if (!nmi_usable) {
180                 kfree(prev_nmi_count);
181                 err = -ENODEV;
182                 goto error;
183         }
184         printk("OK.\n");
185
186         nmi_hz = 1;
187
188         kfree(prev_nmi_count);
189         return 0;
190 error:
191         on_each_cpu(stop_watchdog, NULL, 1);
192         return err;
193 }
194
195 static void start_watchdog(void *unused)
196 {
197         pcr_ops->write(PCR_PIC_PRIV);
198         write_pic(picl_value(nmi_hz));
199
200         pcr_ops->write(pcr_enable);
201 }
202
203 void nmi_adjust_hz(unsigned int new_hz)
204 {
205         nmi_hz = new_hz;
206         on_each_cpu(start_watchdog, NULL, 1);
207 }
208 EXPORT_SYMBOL_GPL(nmi_adjust_hz);
209
210 static int nmi_shutdown(struct notifier_block *nb, unsigned long cmd, void *p)
211 {
212         on_each_cpu(stop_watchdog, NULL, 1);
213         return 0;
214 }
215
216 static struct notifier_block nmi_reboot_notifier = {
217         .notifier_call = nmi_shutdown,
218 };
219
220 int __init nmi_init(void)
221 {
222         int err;
223
224         nmi_usable = 1;
225
226         on_each_cpu(start_watchdog, NULL, 1);
227
228         err = check_nmi_watchdog();
229         if (!err) {
230                 err = register_reboot_notifier(&nmi_reboot_notifier);
231                 if (err) {
232                         nmi_usable = 0;
233                         on_each_cpu(stop_watchdog, NULL, 1);
234                 }
235         }
236         return err;
237 }
238
239 static int __init setup_nmi_watchdog(char *str)
240 {
241         if (!strncmp(str, "panic", 5))
242                 panic_on_timeout = 1;
243
244         return 0;
245 }
246 __setup("nmi_watchdog=", setup_nmi_watchdog);