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