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 static int nmi_init_done;
  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 (__this_cpu_read(nmi_touch)) {
 104                 __this_cpu_write(nmi_touch, 0);
 105                 touched = 1;
 106         }
 107         if (!touched && __this_cpu_read(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                 __this_cpu_write(last_irq_sum, sum);
 114                 __this_cpu_write(alert_counter, 0);
 115         }
 116         if (__this_cpu_read(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         while (endflag == 0)
 134                 mb();
 135 }
 136
 137 static void report_broken_nmi(int cpu, int *prev_nmi_count)
 138 {
 139         printk(KERN_CONT "\n");
 140
 141         printk(KERN_WARNING
 142                 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
 143                         cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
 144
 145         printk(KERN_WARNING
 146                 "Please report this to bugzilla.kernel.org,\n");
 147         printk(KERN_WARNING
 148                 "and attach the output of the 'dmesg' command.\n");
 149
 150         per_cpu(wd_enabled, cpu) = 0;
 151         atomic_dec(&nmi_active);
 152 }
 153
 154 void stop_nmi_watchdog(void *unused)
 155 {
 156         if (!__this_cpu_read(wd_enabled))
 157                 return;
 158         pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
 159         __this_cpu_write(wd_enabled, 0);
 160         atomic_dec(&nmi_active);
 161 }
 162
 163 static int __init check_nmi_watchdog(void)
 164 {
 165         unsigned int *prev_nmi_count;
 166         int cpu, err;
 167
 168         if (!atomic_read(&nmi_active))
 169                 return 0;
 170
 171         prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
 172         if (!prev_nmi_count) {
 173                 err = -ENOMEM;
 174                 goto error;
 175         }
 176
 177         printk(KERN_INFO "Testing NMI watchdog ... ");
 178
 179         smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
 180
 181         for_each_possible_cpu(cpu)
 182                 prev_nmi_count[cpu] = get_nmi_count(cpu);
 183         local_irq_enable();
 184         mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
 185
 186         for_each_online_cpu(cpu) {
 187                 if (!per_cpu(wd_enabled, cpu))
 188                         continue;
 189                 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
 190                         report_broken_nmi(cpu, prev_nmi_count);
 191         }
 192         endflag = 1;
 193         if (!atomic_read(&nmi_active)) {
 194                 kfree(prev_nmi_count);
 195                 atomic_set(&nmi_active, -1);
 196                 err = -ENODEV;
 197                 goto error;
 198         }
 199         printk("OK.\n");
 200
 201         nmi_hz = 1;
 202
 203         kfree(prev_nmi_count);
 204         return 0;
 205 error:
 206         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 207         return err;
 208 }
 209
 210 void start_nmi_watchdog(void *unused)
 211 {
 212         if (__this_cpu_read(wd_enabled))
 213                 return;
 214
 215         __this_cpu_write(wd_enabled, 1);
 216         atomic_inc(&nmi_active);
 217
 218         pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
 219         pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
 220
 221         pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
 222 }
 223
 224 static void nmi_adjust_hz_one(void *unused)
 225 {
 226         if (!__this_cpu_read(wd_enabled))
 227                 return;
 228
 229         pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
 230         pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
 231
 232         pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_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
 267         nmi_init_done = 1;
 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);
 280
 281 /*
 282  * sparc specific NMI watchdog enable function.
 283  * Enables watchdog if it is not enabled already.
 284  */
 285 int watchdog_nmi_enable(unsigned int cpu)
 286 {
 287         if (atomic_read(&nmi_active) == -1) {
 288                 pr_warn("NMI watchdog cannot be enabled or disabled\n");
 289                 return -1;
 290         }
 291
 292         /*
 293          * watchdog thread could start even before nmi_init is called.
 294          * Just Return in that case. Let nmi_init finish the init
 295          * process first.
 296          */
 297         if (!nmi_init_done)
 298                 return 0;
 299
 300         smp_call_function_single(cpu, start_nmi_watchdog, NULL, 1);
 301
 302         return 0;
 303 }
 304 /*
 305  * sparc specific NMI watchdog disable function.
 306  * Disables watchdog if it is not disabled already.
 307  */
 308 void watchdog_nmi_disable(unsigned int cpu)
 309 {
 310         if (atomic_read(&nmi_active) == -1)
 311                 pr_warn_once("NMI watchdog cannot be enabled or disabled\n");
 312         else
 313                 smp_call_function_single(cpu, stop_nmi_watchdog, NULL, 1);
 314 }