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   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/local.h>
  25 #include <asm/pcr.h>
  26
  27 /* We don't have a real NMI on sparc64, but we can fake one
  28  * up using profiling counter overflow interrupts and interrupt
  29  * levels.
  30  *
  31  * The profile overflow interrupts at level 15, so we use
  32  * level 14 as our IRQ off level.
  33  */
  34
  35 static int panic_on_timeout;
  36
  37 /* nmi_active:
  38  * >0: the NMI watchdog is active, but can be disabled
  39  * <0: the NMI watchdog has not been set up, and cannot be enabled
  40  *  0: the NMI watchdog is disabled, but can be enabled
  41  */
  42 atomic_t nmi_active = ATOMIC_INIT(0);           /* oprofile uses this */
  43 EXPORT_SYMBOL(nmi_active);
  44
  45 static unsigned int nmi_hz = HZ;
  46 static DEFINE_PER_CPU(short, wd_enabled);
  47 static int endflag __initdata;
  48
  49 static DEFINE_PER_CPU(unsigned int, last_irq_sum);
  50 static DEFINE_PER_CPU(long, alert_counter);
  51 static DEFINE_PER_CPU(int, nmi_touch);
  52
  53 void touch_nmi_watchdog(void)
  54 {
  55         if (atomic_read(&nmi_active)) {
  56                 int cpu;
  57
  58                 for_each_present_cpu(cpu) {
  59                         if (per_cpu(nmi_touch, cpu) != 1)
  60                                 per_cpu(nmi_touch, cpu) = 1;
  61                 }
  62         }
  63
  64         touch_softlockup_watchdog();
  65 }
  66 EXPORT_SYMBOL(touch_nmi_watchdog);
  67
  68 static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
  69 {
  70         if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
  71                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
  72                 return;
  73
  74         console_verbose();
  75         bust_spinlocks(1);
  76
  77         printk(KERN_EMERG "%s", str);
  78         printk(" on CPU%d, ip %08lx, registers:\n",
  79                smp_processor_id(), regs->tpc);
  80         show_regs(regs);
  81         dump_stack();
  82
  83         bust_spinlocks(0);
  84
  85         if (do_panic || panic_on_oops)
  86                 panic("Non maskable interrupt");
  87
  88         nmi_exit();
  89         local_irq_enable();
  90         do_exit(SIGBUS);
  91 }
  92
  93 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
  94 {
  95         unsigned int sum, touched = 0;
  96         int cpu = smp_processor_id();
  97
  98         clear_softint(1 << irq);
  99
 100         local_cpu_data().__nmi_count++;
 101
 102         nmi_enter();
 103
 104         if (notify_die(DIE_NMI, "nmi", regs, 0,
 105                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
 106                 touched = 1;
 107         else
 108                 pcr_ops->write(PCR_PIC_PRIV);
 109
 110         sum = kstat_irqs_cpu(0, cpu);
 111         if (__get_cpu_var(nmi_touch)) {
 112                 __get_cpu_var(nmi_touch) = 0;
 113                 touched = 1;
 114         }
 115         if (!touched && __get_cpu_var(last_irq_sum) == sum) {
 116                 __this_cpu_inc(per_cpu_var(alert_counter));
 117                 if (__this_cpu_read(per_cpu_var(alert_counter)) == 30 * nmi_hz)
 118                         die_nmi("BUG: NMI Watchdog detected LOCKUP",
 119                                 regs, panic_on_timeout);
 120         } else {
 121                 __get_cpu_var(last_irq_sum) = sum;
 122                 __this_cpu_write(per_cpu_var(alert_counter), 0);
 123         }
 124         if (__get_cpu_var(wd_enabled)) {
 125                 write_pic(picl_value(nmi_hz));
 126                 pcr_ops->write(pcr_enable);
 127         }
 128
 129         nmi_exit();
 130 }
 131
 132 static inline unsigned int get_nmi_count(int cpu)
 133 {
 134         return cpu_data(cpu).__nmi_count;
 135 }
 136
 137 static __init void nmi_cpu_busy(void *data)
 138 {
 139         local_irq_enable_in_hardirq();
 140         while (endflag == 0)
 141                 mb();
 142 }
 143
 144 static void report_broken_nmi(int cpu, int *prev_nmi_count)
 145 {
 146         printk(KERN_CONT "\n");
 147
 148         printk(KERN_WARNING
 149                 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
 150                         cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
 151
 152         printk(KERN_WARNING
 153                 "Please report this to bugzilla.kernel.org,\n");
 154         printk(KERN_WARNING
 155                 "and attach the output of the 'dmesg' command.\n");
 156
 157         per_cpu(wd_enabled, cpu) = 0;
 158         atomic_dec(&nmi_active);
 159 }
 160
 161 void stop_nmi_watchdog(void *unused)
 162 {
 163         pcr_ops->write(PCR_PIC_PRIV);
 164         __get_cpu_var(wd_enabled) = 0;
 165         atomic_dec(&nmi_active);
 166 }
 167
 168 static int __init check_nmi_watchdog(void)
 169 {
 170         unsigned int *prev_nmi_count;
 171         int cpu, err;
 172
 173         if (!atomic_read(&nmi_active))
 174                 return 0;
 175
 176         prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
 177         if (!prev_nmi_count) {
 178                 err = -ENOMEM;
 179                 goto error;
 180         }
 181
 182         printk(KERN_INFO "Testing NMI watchdog ... ");
 183
 184         smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
 185
 186         for_each_possible_cpu(cpu)
 187                 prev_nmi_count[cpu] = get_nmi_count(cpu);
 188         local_irq_enable();
 189         mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
 190
 191         for_each_online_cpu(cpu) {
 192                 if (!per_cpu(wd_enabled, cpu))
 193                         continue;
 194                 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
 195                         report_broken_nmi(cpu, prev_nmi_count);
 196         }
 197         endflag = 1;
 198         if (!atomic_read(&nmi_active)) {
 199                 kfree(prev_nmi_count);
 200                 atomic_set(&nmi_active, -1);
 201                 err = -ENODEV;
 202                 goto error;
 203         }
 204         printk("OK.\n");
 205
 206         nmi_hz = 1;
 207
 208         kfree(prev_nmi_count);
 209         return 0;
 210 error:
 211         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 212         return err;
 213 }
 214
 215 void start_nmi_watchdog(void *unused)
 216 {
 217         __get_cpu_var(wd_enabled) = 1;
 218         atomic_inc(&nmi_active);
 219
 220         pcr_ops->write(PCR_PIC_PRIV);
 221         write_pic(picl_value(nmi_hz));
 222
 223         pcr_ops->write(pcr_enable);
 224 }
 225
 226 static void nmi_adjust_hz_one(void *unused)
 227 {
 228         if (!__get_cpu_var(wd_enabled))
 229                 return;
 230
 231         pcr_ops->write(PCR_PIC_PRIV);
 232         write_pic(picl_value(nmi_hz));
 233
 234         pcr_ops->write(pcr_enable);
 235 }
 236
 237 void nmi_adjust_hz(unsigned int new_hz)
 238 {
 239         nmi_hz = new_hz;
 240         on_each_cpu(nmi_adjust_hz_one, NULL, 1);
 241 }
 242 EXPORT_SYMBOL_GPL(nmi_adjust_hz);
 243
 244 static int nmi_shutdown(struct notifier_block *nb, unsigned long cmd, void *p)
 245 {
 246         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 247         return 0;
 248 }
 249
 250 static struct notifier_block nmi_reboot_notifier = {
 251         .notifier_call = nmi_shutdown,
 252 };
 253
 254 int __init nmi_init(void)
 255 {
 256         int err;
 257
 258         on_each_cpu(start_nmi_watchdog, NULL, 1);
 259
 260         err = check_nmi_watchdog();
 261         if (!err) {
 262                 err = register_reboot_notifier(&nmi_reboot_notifier);
 263                 if (err) {
 264                         on_each_cpu(stop_nmi_watchdog, NULL, 1);
 265                         atomic_set(&nmi_active, -1);
 266                 }
 267         }
 268         if (!err)
 269                 init_hw_perf_events();
 270
 271         return err;
 272 }
 273
 274 static int __init setup_nmi_watchdog(char *str)
 275 {
 276         if (!strncmp(str, "panic", 5))
 277                 panic_on_timeout = 1;
 278
 279         return 0;
 280 }
 281 __setup("nmi_watchdog=", setup_nmi_watchdog);