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         if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
  72                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
  73                 return;
  74
  75         console_verbose();
  76         bust_spinlocks(1);
  77
  78         printk(KERN_EMERG "%s", str);
  79         printk(" on CPU%d, ip %08lx, registers:\n",
  80                smp_processor_id(), regs->tpc);
  81         show_regs(regs);
  82         dump_stack();
  83
  84         bust_spinlocks(0);
  85
  86         if (do_panic || panic_on_oops)
  87                 panic("Non maskable interrupt");
  88
  89         nmi_exit();
  90         local_irq_enable();
  91         do_exit(SIGBUS);
  92 }
  93
  94 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
  95 {
  96         unsigned int sum, touched = 0;
  97         void *orig_sp;
  98
  99         clear_softint(1 << irq);
 100
 101         local_cpu_data().__nmi_count++;
 102
 103         nmi_enter();
 104
 105         orig_sp = set_hardirq_stack();
 106
 107         if (notify_die(DIE_NMI, "nmi", regs, 0,
 108                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
 109                 touched = 1;
 110         else
 111                 pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
 112
 113         sum = local_cpu_data().irq0_irqs;
 114         if (__get_cpu_var(nmi_touch)) {
 115                 __get_cpu_var(nmi_touch) = 0;
 116                 touched = 1;
 117         }
 118         if (!touched && __get_cpu_var(last_irq_sum) == sum) {
 119                 __this_cpu_inc(alert_counter);
 120                 if (__this_cpu_read(alert_counter) == 30 * nmi_hz)
 121                         die_nmi("BUG: NMI Watchdog detected LOCKUP",
 122                                 regs, panic_on_timeout);
 123         } else {
 124                 __get_cpu_var(last_irq_sum) = sum;
 125                 __this_cpu_write(alert_counter, 0);
 126         }
 127         if (__get_cpu_var(wd_enabled)) {
 128                 pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
 129                 pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
 130         }
 131
 132         restore_hardirq_stack(orig_sp);
 133
 134         nmi_exit();
 135 }
 136
 137 static inline unsigned int get_nmi_count(int cpu)
 138 {
 139         return cpu_data(cpu).__nmi_count;
 140 }
 141
 142 static __init void nmi_cpu_busy(void *data)
 143 {
 144         local_irq_enable_in_hardirq();
 145         while (endflag == 0)
 146                 mb();
 147 }
 148
 149 static void report_broken_nmi(int cpu, int *prev_nmi_count)
 150 {
 151         printk(KERN_CONT "\n");
 152
 153         printk(KERN_WARNING
 154                 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
 155                         cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
 156
 157         printk(KERN_WARNING
 158                 "Please report this to bugzilla.kernel.org,\n");
 159         printk(KERN_WARNING
 160                 "and attach the output of the 'dmesg' command.\n");
 161
 162         per_cpu(wd_enabled, cpu) = 0;
 163         atomic_dec(&nmi_active);
 164 }
 165
 166 void stop_nmi_watchdog(void *unused)
 167 {
 168         pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
 169         __get_cpu_var(wd_enabled) = 0;
 170         atomic_dec(&nmi_active);
 171 }
 172
 173 static int __init check_nmi_watchdog(void)
 174 {
 175         unsigned int *prev_nmi_count;
 176         int cpu, err;
 177
 178         if (!atomic_read(&nmi_active))
 179                 return 0;
 180
 181         prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
 182         if (!prev_nmi_count) {
 183                 err = -ENOMEM;
 184                 goto error;
 185         }
 186
 187         printk(KERN_INFO "Testing NMI watchdog ... ");
 188
 189         smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
 190
 191         for_each_possible_cpu(cpu)
 192                 prev_nmi_count[cpu] = get_nmi_count(cpu);
 193         local_irq_enable();
 194         mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
 195
 196         for_each_online_cpu(cpu) {
 197                 if (!per_cpu(wd_enabled, cpu))
 198                         continue;
 199                 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
 200                         report_broken_nmi(cpu, prev_nmi_count);
 201         }
 202         endflag = 1;
 203         if (!atomic_read(&nmi_active)) {
 204                 kfree(prev_nmi_count);
 205                 atomic_set(&nmi_active, -1);
 206                 err = -ENODEV;
 207                 goto error;
 208         }
 209         printk("OK.\n");
 210
 211         nmi_hz = 1;
 212
 213         kfree(prev_nmi_count);
 214         return 0;
 215 error:
 216         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 217         return err;
 218 }
 219
 220 void start_nmi_watchdog(void *unused)
 221 {
 222         __get_cpu_var(wd_enabled) = 1;
 223         atomic_inc(&nmi_active);
 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 static void nmi_adjust_hz_one(void *unused)
 232 {
 233         if (!__get_cpu_var(wd_enabled))
 234                 return;
 235
 236         pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_disable);
 237         pcr_ops->write_pic(0, pcr_ops->nmi_picl_value(nmi_hz));
 238
 239         pcr_ops->write_pcr(0, pcr_ops->pcr_nmi_enable);
 240 }
 241
 242 void nmi_adjust_hz(unsigned int new_hz)
 243 {
 244         nmi_hz = new_hz;
 245         on_each_cpu(nmi_adjust_hz_one, NULL, 1);
 246 }
 247 EXPORT_SYMBOL_GPL(nmi_adjust_hz);
 248
 249 static int nmi_shutdown(struct notifier_block *nb, unsigned long cmd, void *p)
 250 {
 251         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 252         return 0;
 253 }
 254
 255 static struct notifier_block nmi_reboot_notifier = {
 256         .notifier_call = nmi_shutdown,
 257 };
 258
 259 int __init nmi_init(void)
 260 {
 261         int err;
 262
 263         on_each_cpu(start_nmi_watchdog, NULL, 1);
 264
 265         err = check_nmi_watchdog();
 266         if (!err) {
 267                 err = register_reboot_notifier(&nmi_reboot_notifier);
 268                 if (err) {
 269                         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 270                         atomic_set(&nmi_active, -1);
 271                 }
 272         }
 273
 274         return err;
 275 }
 276
 277 static int __init setup_nmi_watchdog(char *str)
 278 {
 279         if (!strncmp(str, "panic", 5))
 280                 panic_on_timeout = 1;
 281
 282         return 0;
 283 }
 284 __setup("nmi_watchdog=", setup_nmi_watchdog);