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 #include <asm/perfctr.h>
  26
  27 #include "kstack.h"
  28
  29 /* We don't have a real NMI on sparc64, but we can fake one
  30  * up using profiling counter overflow interrupts and interrupt
  31  * levels.
  32  *
  33  * The profile overflow interrupts at level 15, so we use
  34  * level 14 as our IRQ off level.
  35  */
  36
  37 static int panic_on_timeout;
  38
  39 /* nmi_active:
  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
  43  */
  44 atomic_t nmi_active = ATOMIC_INIT(0);           /* oprofile uses this */
  45 EXPORT_SYMBOL(nmi_active);
  46
  47 static unsigned int nmi_hz = HZ;
  48 static DEFINE_PER_CPU(short, wd_enabled);
  49 static int endflag __initdata;
  50
  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);
  54
  55 void touch_nmi_watchdog(void)
  56 {
  57         if (atomic_read(&nmi_active)) {
  58                 int cpu;
  59
  60                 for_each_present_cpu(cpu) {
  61                         if (per_cpu(nmi_touch, cpu) != 1)
  62                                 per_cpu(nmi_touch, cpu) = 1;
  63                 }
  64         }
  65
  66         touch_softlockup_watchdog();
  67 }
  68 EXPORT_SYMBOL(touch_nmi_watchdog);
  69
  70 static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
  71 {
  72         if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
  73                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
  74                 return;
  75
  76         console_verbose();
  77         bust_spinlocks(1);
  78
  79         printk(KERN_EMERG "%s", str);
  80         printk(" on CPU%d, ip %08lx, registers:\n",
  81                smp_processor_id(), regs->tpc);
  82         show_regs(regs);
  83         dump_stack();
  84
  85         bust_spinlocks(0);
  86
  87         if (do_panic || panic_on_oops)
  88                 panic("Non maskable interrupt");
  89
  90         nmi_exit();
  91         local_irq_enable();
  92         do_exit(SIGBUS);
  93 }
  94
  95 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
  96 {
  97         unsigned int sum, touched = 0;
  98         void *orig_sp;
  99
 100         clear_softint(1 << irq);
 101
 102         local_cpu_data().__nmi_count++;
 103
 104         nmi_enter();
 105
 106         orig_sp = set_hardirq_stack();
 107
 108         if (notify_die(DIE_NMI, "nmi", regs, 0,
 109                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
 110                 touched = 1;
 111         else
 112                 pcr_ops->write(PCR_PIC_PRIV);
 113
 114         sum = local_cpu_data().irq0_irqs;
 115         if (__get_cpu_var(nmi_touch)) {
 116                 __get_cpu_var(nmi_touch) = 0;
 117                 touched = 1;
 118         }
 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);
 124         } else {
 125                 __get_cpu_var(last_irq_sum) = sum;
 126                 __this_cpu_write(alert_counter, 0);
 127         }
 128         if (__get_cpu_var(wd_enabled)) {
 129                 write_pic(picl_value(nmi_hz));
 130                 pcr_ops->write(pcr_enable);
 131         }
 132
 133         restore_hardirq_stack(orig_sp);
 134
 135         nmi_exit();
 136 }
 137
 138 static inline unsigned int get_nmi_count(int cpu)
 139 {
 140         return cpu_data(cpu).__nmi_count;
 141 }
 142
 143 static __init void nmi_cpu_busy(void *data)
 144 {
 145         local_irq_enable_in_hardirq();
 146         while (endflag == 0)
 147                 mb();
 148 }
 149
 150 static void report_broken_nmi(int cpu, int *prev_nmi_count)
 151 {
 152         printk(KERN_CONT "\n");
 153
 154         printk(KERN_WARNING
 155                 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
 156                         cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
 157
 158         printk(KERN_WARNING
 159                 "Please report this to bugzilla.kernel.org,\n");
 160         printk(KERN_WARNING
 161                 "and attach the output of the 'dmesg' command.\n");
 162
 163         per_cpu(wd_enabled, cpu) = 0;
 164         atomic_dec(&nmi_active);
 165 }
 166
 167 void stop_nmi_watchdog(void *unused)
 168 {
 169         pcr_ops->write(PCR_PIC_PRIV);
 170         __get_cpu_var(wd_enabled) = 0;
 171         atomic_dec(&nmi_active);
 172 }
 173
 174 static int __init check_nmi_watchdog(void)
 175 {
 176         unsigned int *prev_nmi_count;
 177         int cpu, err;
 178
 179         if (!atomic_read(&nmi_active))
 180                 return 0;
 181
 182         prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
 183         if (!prev_nmi_count) {
 184                 err = -ENOMEM;
 185                 goto error;
 186         }
 187
 188         printk(KERN_INFO "Testing NMI watchdog ... ");
 189
 190         smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
 191
 192         for_each_possible_cpu(cpu)
 193                 prev_nmi_count[cpu] = get_nmi_count(cpu);
 194         local_irq_enable();
 195         mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
 196
 197         for_each_online_cpu(cpu) {
 198                 if (!per_cpu(wd_enabled, cpu))
 199                         continue;
 200                 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
 201                         report_broken_nmi(cpu, prev_nmi_count);
 202         }
 203         endflag = 1;
 204         if (!atomic_read(&nmi_active)) {
 205                 kfree(prev_nmi_count);
 206                 atomic_set(&nmi_active, -1);
 207                 err = -ENODEV;
 208                 goto error;
 209         }
 210         printk("OK.\n");
 211
 212         nmi_hz = 1;
 213
 214         kfree(prev_nmi_count);
 215         return 0;
 216 error:
 217         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 218         return err;
 219 }
 220
 221 void start_nmi_watchdog(void *unused)
 222 {
 223         __get_cpu_var(wd_enabled) = 1;
 224         atomic_inc(&nmi_active);
 225
 226         pcr_ops->write(PCR_PIC_PRIV);
 227         write_pic(picl_value(nmi_hz));
 228
 229         pcr_ops->write(pcr_enable);
 230 }
 231
 232 static void nmi_adjust_hz_one(void *unused)
 233 {
 234         if (!__get_cpu_var(wd_enabled))
 235                 return;
 236
 237         pcr_ops->write(PCR_PIC_PRIV);
 238         write_pic(picl_value(nmi_hz));
 239
 240         pcr_ops->write(pcr_enable);
 241 }
 242
 243 void nmi_adjust_hz(unsigned int new_hz)
 244 {
 245         nmi_hz = new_hz;
 246         on_each_cpu(nmi_adjust_hz_one, NULL, 1);
 247 }
 248 EXPORT_SYMBOL_GPL(nmi_adjust_hz);
 249
 250 static int nmi_shutdown(struct notifier_block *nb, unsigned long cmd, void *p)
 251 {
 252         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 253         return 0;
 254 }
 255
 256 static struct notifier_block nmi_reboot_notifier = {
 257         .notifier_call = nmi_shutdown,
 258 };
 259
 260 int __init nmi_init(void)
 261 {
 262         int err;
 263
 264         on_each_cpu(start_nmi_watchdog, NULL, 1);
 265
 266         err = check_nmi_watchdog();
 267         if (!err) {
 268                 err = register_reboot_notifier(&nmi_reboot_notifier);
 269                 if (err) {
 270                         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 271                         atomic_set(&nmi_active, -1);
 272                 }
 273         }
 274
 275         return err;
 276 }
 277
 278 static int __init setup_nmi_watchdog(char *str)
 279 {
 280         if (!strncmp(str, "panic", 5))
 281                 panic_on_timeout = 1;
 282
 283         return 0;
 284 }
 285 __setup("nmi_watchdog=", setup_nmi_watchdog);