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/slab.h>
17 #include <linux/kdebug.h>
18 #include <linux/delay.h>
19 #include <linux/smp.h>
20
21 #include <asm/ptrace.h>
22 #include <asm/local.h>
23 #include <asm/pcr.h>
24
25 /* We don't have a real NMI on sparc64, but we can fake one
26 * up using profiling counter overflow interrupts and interrupt
27 * levels.
28 *
29 * The profile overflow interrupts at level 15, so we use
30 * level 14 as our IRQ off level.
31 */
32
33 static int nmi_watchdog_active;
34 static int panic_on_timeout;
35
36 int nmi_usable;
37 EXPORT_SYMBOL_GPL(nmi_usable);
38
39 static unsigned int nmi_hz = HZ;
40
41 static DEFINE_PER_CPU(unsigned int, last_irq_sum);
42 static DEFINE_PER_CPU(local_t, alert_counter);
43 static DEFINE_PER_CPU(int, nmi_touch);
44
touch_nmi_watchdog(void)45 void touch_nmi_watchdog(void)
46 {
47 if (nmi_watchdog_active) {
48 int cpu;
49
50 for_each_present_cpu(cpu) {
51 if (per_cpu(nmi_touch, cpu) != 1)
52 per_cpu(nmi_touch, cpu) = 1;
53 }
54 }
55
56 touch_softlockup_watchdog();
57 }
58 EXPORT_SYMBOL(touch_nmi_watchdog);
59
die_nmi(const char * str,struct pt_regs * regs,int do_panic)60 static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
61 {
62 if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
63 pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
64 return;
65
66 console_verbose();
67 bust_spinlocks(1);
68
69 printk(KERN_EMERG "%s", str);
70 printk(" on CPU%d, ip %08lx, registers:\n",
71 smp_processor_id(), regs->tpc);
72 show_regs(regs);
73 dump_stack();
74
75 bust_spinlocks(0);
76
77 if (do_panic || panic_on_oops)
78 panic("Non maskable interrupt");
79
80 local_irq_enable();
81 do_exit(SIGBUS);
82 }
83
perfctr_irq(int irq,struct pt_regs * regs)84 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
85 {
86 unsigned int sum, touched = 0;
87 int cpu = smp_processor_id();
88
89 clear_softint(1 << irq);
90 pcr_ops->write(PCR_PIC_PRIV);
91
92 local_cpu_data().__nmi_count++;
93
94 if (notify_die(DIE_NMI, "nmi", regs, 0,
95 pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
96 touched = 1;
97
98 sum = kstat_irqs_cpu(0, cpu);
99 if (__get_cpu_var(nmi_touch)) {
100 __get_cpu_var(nmi_touch) = 0;
101 touched = 1;
102 }
103 if (!touched && __get_cpu_var(last_irq_sum) == sum) {
104 local_inc(&__get_cpu_var(alert_counter));
105 if (local_read(&__get_cpu_var(alert_counter)) == 5 * nmi_hz)
106 die_nmi("BUG: NMI Watchdog detected LOCKUP",
107 regs, panic_on_timeout);
108 } else {
109 __get_cpu_var(last_irq_sum) = sum;
110 local_set(&__get_cpu_var(alert_counter), 0);
111 }
112 if (nmi_usable) {
113 write_pic(picl_value(nmi_hz));
114 pcr_ops->write(pcr_enable);
115 }
116 }
117
get_nmi_count(int cpu)118 static inline unsigned int get_nmi_count(int cpu)
119 {
120 return cpu_data(cpu).__nmi_count;
121 }
122
123 static int endflag __initdata;
124
nmi_cpu_busy(void * data)125 static __init void nmi_cpu_busy(void *data)
126 {
127 local_irq_enable_in_hardirq();
128 while (endflag == 0)
129 mb();
130 }
131
report_broken_nmi(int cpu,int * prev_nmi_count)132 static void report_broken_nmi(int cpu, int *prev_nmi_count)
133 {
134 printk(KERN_CONT "\n");
135
136 printk(KERN_WARNING
137 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
138 cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
139
140 printk(KERN_WARNING
141 "Please report this to bugzilla.kernel.org,\n");
142 printk(KERN_WARNING
143 "and attach the output of the 'dmesg' command.\n");
144
145 nmi_usable = 0;
146 }
147
stop_watchdog(void * unused)148 static void stop_watchdog(void *unused)
149 {
150 pcr_ops->write(PCR_PIC_PRIV);
151 }
152
check_nmi_watchdog(void)153 static int __init check_nmi_watchdog(void)
154 {
155 unsigned int *prev_nmi_count;
156 int cpu, err;
157
158 prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
159 if (!prev_nmi_count) {
160 err = -ENOMEM;
161 goto error;
162 }
163
164 printk(KERN_INFO "Testing NMI watchdog ... ");
165
166 smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
167
168 for_each_possible_cpu(cpu)
169 prev_nmi_count[cpu] = get_nmi_count(cpu);
170 local_irq_enable();
171 mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
172
173 for_each_online_cpu(cpu) {
174 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
175 report_broken_nmi(cpu, prev_nmi_count);
176 }
177 endflag = 1;
178 if (!nmi_usable) {
179 kfree(prev_nmi_count);
180 err = -ENODEV;
181 goto error;
182 }
183 printk("OK.\n");
184
185 nmi_hz = 1;
186
187 kfree(prev_nmi_count);
188 return 0;
189 error:
190 on_each_cpu(stop_watchdog, NULL, 1);
191 return err;
192 }
193
start_watchdog(void * unused)194 static void start_watchdog(void *unused)
195 {
196 pcr_ops->write(PCR_PIC_PRIV);
197 write_pic(picl_value(nmi_hz));
198
199 pcr_ops->write(pcr_enable);
200 }
201
nmi_adjust_hz(unsigned int new_hz)202 void nmi_adjust_hz(unsigned int new_hz)
203 {
204 nmi_hz = new_hz;
205 on_each_cpu(start_watchdog, NULL, 1);
206 }
207 EXPORT_SYMBOL_GPL(nmi_adjust_hz);
208
nmi_init(void)209 int __init nmi_init(void)
210 {
211 nmi_usable = 1;
212
213 on_each_cpu(start_watchdog, NULL, 1);
214
215 return check_nmi_watchdog();
216 }
217
setup_nmi_watchdog(char * str)218 static int __init setup_nmi_watchdog(char *str)
219 {
220 if (!strncmp(str, "panic", 5))
221 panic_on_timeout = 1;
222
223 return 0;
224 }
225 __setup("nmi_watchdog=", setup_nmi_watchdog);
226