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/module.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 /* We don't have a real NMI on sparc64, but we can fake one
  27  * up using profiling counter overflow interrupts and interrupt
  28  * levels.
  29  *
  30  * The profile overflow interrupts at level 15, so we use
  31  * level 14 as our IRQ off level.
  32  */
  33
  34 static int panic_on_timeout;
  35
  36 /* nmi_active:
  37  * >0: the NMI watchdog is active, but can be disabled
  38  * <0: the NMI watchdog has not been set up, and cannot be enabled
  39  *  0: the NMI watchdog is disabled, but can be enabled
  40  */
  41 atomic_t nmi_active = ATOMIC_INIT(0);           /* oprofile uses this */
  42 EXPORT_SYMBOL(nmi_active);
  43
  44 static unsigned int nmi_hz = HZ;
  45 static DEFINE_PER_CPU(short, wd_enabled);
  46 static int endflag __initdata;
  47
  48 static DEFINE_PER_CPU(unsigned int, last_irq_sum);
  49 static DEFINE_PER_CPU(long, alert_counter);
  50 static DEFINE_PER_CPU(int, nmi_touch);
  51
  52 void touch_nmi_watchdog(void)
  53 {
  54         if (atomic_read(&nmi_active)) {
  55                 int cpu;
  56
  57                 for_each_present_cpu(cpu) {
  58                         if (per_cpu(nmi_touch, cpu) != 1)
  59                                 per_cpu(nmi_touch, cpu) = 1;
  60                 }
  61         }
  62
  63         touch_softlockup_watchdog();
  64 }
  65 EXPORT_SYMBOL(touch_nmi_watchdog);
  66
  67 static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
  68 {
  69         if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
  70                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
  71                 return;
  72
  73         console_verbose();
  74         bust_spinlocks(1);
  75
  76         printk(KERN_EMERG "%s", str);
  77         printk(" on CPU%d, ip %08lx, registers:\n",
  78                smp_processor_id(), regs->tpc);
  79         show_regs(regs);
  80         dump_stack();
  81
  82         bust_spinlocks(0);
  83
  84         if (do_panic || panic_on_oops)
  85                 panic("Non maskable interrupt");
  86
  87         nmi_exit();
  88         local_irq_enable();
  89         do_exit(SIGBUS);
  90 }
  91
  92 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
  93 {
  94         unsigned int sum, touched = 0;
  95
  96         clear_softint(1 << irq);
  97
  98         local_cpu_data().__nmi_count++;
  99
 100         nmi_enter();
 101
 102         if (notify_die(DIE_NMI, "nmi", regs, 0,
 103                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
 104                 touched = 1;
 105         else
 106                 pcr_ops->write(PCR_PIC_PRIV);
 107
 108         sum = local_cpu_data().irq0_irqs;
 109         if (__get_cpu_var(nmi_touch)) {
 110                 __get_cpu_var(nmi_touch) = 0;
 111                 touched = 1;
 112         }
 113         if (!touched && __get_cpu_var(last_irq_sum) == sum) {
 114                 __this_cpu_inc(alert_counter);
 115                 if (__this_cpu_read(alert_counter) == 30 * nmi_hz)
 116                         die_nmi("BUG: NMI Watchdog detected LOCKUP",
 117                                 regs, panic_on_timeout);
 118         } else {
 119                 __get_cpu_var(last_irq_sum) = sum;
 120                 __this_cpu_write(alert_counter, 0);
 121         }
 122         if (__get_cpu_var(wd_enabled)) {
 123                 write_pic(picl_value(nmi_hz));
 124                 pcr_ops->write(pcr_enable);
 125         }
 126
 127         nmi_exit();
 128 }
 129
 130 static inline unsigned int get_nmi_count(int cpu)
 131 {
 132         return cpu_data(cpu).__nmi_count;
 133 }
 134
 135 static __init void nmi_cpu_busy(void *data)
 136 {
 137         local_irq_enable_in_hardirq();
 138         while (endflag == 0)
 139                 mb();
 140 }
 141
 142 static void report_broken_nmi(int cpu, int *prev_nmi_count)
 143 {
 144         printk(KERN_CONT "\n");
 145
 146         printk(KERN_WARNING
 147                 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
 148                         cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
 149
 150         printk(KERN_WARNING
 151                 "Please report this to bugzilla.kernel.org,\n");
 152         printk(KERN_WARNING
 153                 "and attach the output of the 'dmesg' command.\n");
 154
 155         per_cpu(wd_enabled, cpu) = 0;
 156         atomic_dec(&nmi_active);
 157 }
 158
 159 void stop_nmi_watchdog(void *unused)
 160 {
 161         pcr_ops->write(PCR_PIC_PRIV);
 162         __get_cpu_var(wd_enabled) = 0;
 163         atomic_dec(&nmi_active);
 164 }
 165
 166 static int __init check_nmi_watchdog(void)
 167 {
 168         unsigned int *prev_nmi_count;
 169         int cpu, err;
 170
 171         if (!atomic_read(&nmi_active))
 172                 return 0;
 173
 174         prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
 175         if (!prev_nmi_count) {
 176                 err = -ENOMEM;
 177                 goto error;
 178         }
 179
 180         printk(KERN_INFO "Testing NMI watchdog ... ");
 181
 182         smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
 183
 184         for_each_possible_cpu(cpu)
 185                 prev_nmi_count[cpu] = get_nmi_count(cpu);
 186         local_irq_enable();
 187         mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
 188
 189         for_each_online_cpu(cpu) {
 190                 if (!per_cpu(wd_enabled, cpu))
 191                         continue;
 192                 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
 193                         report_broken_nmi(cpu, prev_nmi_count);
 194         }
 195         endflag = 1;
 196         if (!atomic_read(&nmi_active)) {
 197                 kfree(prev_nmi_count);
 198                 atomic_set(&nmi_active, -1);
 199                 err = -ENODEV;
 200                 goto error;
 201         }
 202         printk("OK.\n");
 203
 204         nmi_hz = 1;
 205
 206         kfree(prev_nmi_count);
 207         return 0;
 208 error:
 209         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 210         return err;
 211 }
 212
 213 void start_nmi_watchdog(void *unused)
 214 {
 215         __get_cpu_var(wd_enabled) = 1;
 216         atomic_inc(&nmi_active);
 217
 218         pcr_ops->write(PCR_PIC_PRIV);
 219         write_pic(picl_value(nmi_hz));
 220
 221         pcr_ops->write(pcr_enable);
 222 }
 223
 224 static void nmi_adjust_hz_one(void *unused)
 225 {
 226         if (!__get_cpu_var(wd_enabled))
 227                 return;
 228
 229         pcr_ops->write(PCR_PIC_PRIV);
 230         write_pic(picl_value(nmi_hz));
 231
 232         pcr_ops->write(pcr_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         if (!err)
 267                 init_hw_perf_events();
 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);