1 /* Pseudo NMI support on sparc64 systems.
3 * Copyright (C) 2009 David S. Miller <davem@davemloft.net>
5 * The NMI watchdog support and infrastructure is based almost
6 * entirely upon the x86 NMI support code.
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>
22 #include <asm/perf_event.h>
23 #include <asm/ptrace.h>
25 #include <asm/perfctr.h>
29 /* We don't have a real NMI on sparc64, but we can fake one
30 * up using profiling counter overflow interrupts and interrupt
33 * The profile overflow interrupts at level 15, so we use
34 * level 14 as our IRQ off level.
37 static int panic_on_timeout;
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
44 atomic_t nmi_active = ATOMIC_INIT(0); /* oprofile uses this */
45 EXPORT_SYMBOL(nmi_active);
47 static unsigned int nmi_hz = HZ;
48 static DEFINE_PER_CPU(short, wd_enabled);
49 static int endflag __initdata;
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);
55 void touch_nmi_watchdog(void)
57 if (atomic_read(&nmi_active)) {
60 for_each_present_cpu(cpu) {
61 if (per_cpu(nmi_touch, cpu) != 1)
62 per_cpu(nmi_touch, cpu) = 1;
66 touch_softlockup_watchdog();
68 EXPORT_SYMBOL(touch_nmi_watchdog);
70 static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
72 if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
73 pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
79 printk(KERN_EMERG "%s", str);
80 printk(" on CPU%d, ip %08lx, registers:\n",
81 smp_processor_id(), regs->tpc);
87 if (do_panic || panic_on_oops)
88 panic("Non maskable interrupt");
95 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
97 unsigned int sum, touched = 0;
100 clear_softint(1 << irq);
102 local_cpu_data().__nmi_count++;
106 orig_sp = set_hardirq_stack();
108 if (notify_die(DIE_NMI, "nmi", regs, 0,
109 pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
112 pcr_ops->write(PCR_PIC_PRIV);
114 sum = local_cpu_data().irq0_irqs;
115 if (__get_cpu_var(nmi_touch)) {
116 __get_cpu_var(nmi_touch) = 0;
119 if (!touched && __get_cpu_var(last_irq_sum) == sum) {
120 __this_cpu_inc(alert_counter);
121 if (__this_cpu_read(alert_counter) == 30 * nmi_hz)
122 die_nmi("BUG: NMI Watchdog detected LOCKUP",
123 regs, panic_on_timeout);
125 __get_cpu_var(last_irq_sum) = sum;
126 __this_cpu_write(alert_counter, 0);
128 if (__get_cpu_var(wd_enabled)) {
129 write_pic(picl_value(nmi_hz));
130 pcr_ops->write(pcr_enable);
133 restore_hardirq_stack(orig_sp);
138 static inline unsigned int get_nmi_count(int cpu)
140 return cpu_data(cpu).__nmi_count;
143 static __init void nmi_cpu_busy(void *data)
145 local_irq_enable_in_hardirq();
150 static void report_broken_nmi(int cpu, int *prev_nmi_count)
152 printk(KERN_CONT "\n");
155 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
156 cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
159 "Please report this to bugzilla.kernel.org,\n");
161 "and attach the output of the 'dmesg' command.\n");
163 per_cpu(wd_enabled, cpu) = 0;
164 atomic_dec(&nmi_active);
167 void stop_nmi_watchdog(void *unused)
169 pcr_ops->write(PCR_PIC_PRIV);
170 __get_cpu_var(wd_enabled) = 0;
171 atomic_dec(&nmi_active);
174 static int __init check_nmi_watchdog(void)
176 unsigned int *prev_nmi_count;
179 if (!atomic_read(&nmi_active))
182 prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
183 if (!prev_nmi_count) {
188 printk(KERN_INFO "Testing NMI watchdog ... ");
190 smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
192 for_each_possible_cpu(cpu)
193 prev_nmi_count[cpu] = get_nmi_count(cpu);
195 mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
197 for_each_online_cpu(cpu) {
198 if (!per_cpu(wd_enabled, cpu))
200 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
201 report_broken_nmi(cpu, prev_nmi_count);
204 if (!atomic_read(&nmi_active)) {
205 kfree(prev_nmi_count);
206 atomic_set(&nmi_active, -1);
214 kfree(prev_nmi_count);
217 on_each_cpu(stop_nmi_watchdog, NULL, 1);
221 void start_nmi_watchdog(void *unused)
223 __get_cpu_var(wd_enabled) = 1;
224 atomic_inc(&nmi_active);
226 pcr_ops->write(PCR_PIC_PRIV);
227 write_pic(picl_value(nmi_hz));
229 pcr_ops->write(pcr_enable);
232 static void nmi_adjust_hz_one(void *unused)
234 if (!__get_cpu_var(wd_enabled))
237 pcr_ops->write(PCR_PIC_PRIV);
238 write_pic(picl_value(nmi_hz));
240 pcr_ops->write(pcr_enable);
243 void nmi_adjust_hz(unsigned int new_hz)
246 on_each_cpu(nmi_adjust_hz_one, NULL, 1);
248 EXPORT_SYMBOL_GPL(nmi_adjust_hz);
250 static int nmi_shutdown(struct notifier_block *nb, unsigned long cmd, void *p)
252 on_each_cpu(stop_nmi_watchdog, NULL, 1);
256 static struct notifier_block nmi_reboot_notifier = {
257 .notifier_call = nmi_shutdown,
260 int __init nmi_init(void)
264 on_each_cpu(start_nmi_watchdog, NULL, 1);
266 err = check_nmi_watchdog();
268 err = register_reboot_notifier(&nmi_reboot_notifier);
270 on_each_cpu(stop_nmi_watchdog, NULL, 1);
271 atomic_set(&nmi_active, -1);
278 static int __init setup_nmi_watchdog(char *str)
280 if (!strncmp(str, "panic", 5))
281 panic_on_timeout = 1;
285 __setup("nmi_watchdog=", setup_nmi_watchdog);