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/ptrace.h>
  23 #include <asm/local.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 nmi_watchdog_active;
  35 static int panic_on_timeout;
  36
  37 int nmi_usable;
  38 EXPORT_SYMBOL_GPL(nmi_usable);
  39
  40 static unsigned int nmi_hz = HZ;
  41
  42 static DEFINE_PER_CPU(unsigned int, last_irq_sum);
  43 static DEFINE_PER_CPU(local_t, alert_counter);
  44 static DEFINE_PER_CPU(int, nmi_touch);
  45
  46 void touch_nmi_watchdog(void)
  47 {
  48         if (nmi_watchdog_active) {
  49                 int cpu;
  50
  51                 for_each_present_cpu(cpu) {
  52                         if (per_cpu(nmi_touch, cpu) != 1)
  53                                 per_cpu(nmi_touch, cpu) = 1;
  54                 }
  55         }
  56
  57         touch_softlockup_watchdog();
  58 }
  59 EXPORT_SYMBOL(touch_nmi_watchdog);
  60
  61 static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
  62 {
  63         if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
  64                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
  65                 return;
  66
  67         console_verbose();
  68         bust_spinlocks(1);
  69
  70         printk(KERN_EMERG "%s", str);
  71         printk(" on CPU%d, ip %08lx, registers:\n",
  72                smp_processor_id(), regs->tpc);
  73         show_regs(regs);
  74         dump_stack();
  75
  76         bust_spinlocks(0);
  77
  78         if (do_panic || panic_on_oops)
  79                 panic("Non maskable interrupt");
  80
  81         local_irq_enable();
  82         do_exit(SIGBUS);
  83 }
  84
  85 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
  86 {
  87         unsigned int sum, touched = 0;
  88         int cpu = smp_processor_id();
  89
  90         clear_softint(1 << irq);
  91         pcr_ops->write(PCR_PIC_PRIV);
  92
  93         local_cpu_data().__nmi_count++;
  94
  95         if (notify_die(DIE_NMI, "nmi", regs, 0,
  96                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
  97                 touched = 1;
  98
  99         sum = kstat_irqs_cpu(0, cpu);
 100         if (__get_cpu_var(nmi_touch)) {
 101                 __get_cpu_var(nmi_touch) = 0;
 102                 touched = 1;
 103         }
 104         if (!touched && __get_cpu_var(last_irq_sum) == sum) {
 105                 local_inc(&__get_cpu_var(alert_counter));
 106                 if (local_read(&__get_cpu_var(alert_counter)) == 30 * nmi_hz)
 107                         die_nmi("BUG: NMI Watchdog detected LOCKUP",
 108                                 regs, panic_on_timeout);
 109         } else {
 110                 __get_cpu_var(last_irq_sum) = sum;
 111                 local_set(&__get_cpu_var(alert_counter), 0);
 112         }
 113         if (nmi_usable) {
 114                 write_pic(picl_value(nmi_hz));
 115                 pcr_ops->write(pcr_enable);
 116         }
 117 }
 118
 119 static inline unsigned int get_nmi_count(int cpu)
 120 {
 121         return cpu_data(cpu).__nmi_count;
 122 }
 123
 124 static int endflag __initdata;
 125
 126 static __init void nmi_cpu_busy(void *data)
 127 {
 128         local_irq_enable_in_hardirq();
 129         while (endflag == 0)
 130                 mb();
 131 }
 132
 133 static void report_broken_nmi(int cpu, int *prev_nmi_count)
 134 {
 135         printk(KERN_CONT "\n");
 136
 137         printk(KERN_WARNING
 138                 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
 139                         cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
 140
 141         printk(KERN_WARNING
 142                 "Please report this to bugzilla.kernel.org,\n");
 143         printk(KERN_WARNING
 144                 "and attach the output of the 'dmesg' command.\n");
 145
 146         nmi_usable = 0;
 147 }
 148
 149 static void stop_watchdog(void *unused)
 150 {
 151         pcr_ops->write(PCR_PIC_PRIV);
 152 }
 153
 154 static int __init check_nmi_watchdog(void)
 155 {
 156         unsigned int *prev_nmi_count;
 157         int cpu, err;
 158
 159         prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
 160         if (!prev_nmi_count) {
 161                 err = -ENOMEM;
 162                 goto error;
 163         }
 164
 165         printk(KERN_INFO "Testing NMI watchdog ... ");
 166
 167         smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
 168
 169         for_each_possible_cpu(cpu)
 170                 prev_nmi_count[cpu] = get_nmi_count(cpu);
 171         local_irq_enable();
 172         mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
 173
 174         for_each_online_cpu(cpu) {
 175                 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
 176                         report_broken_nmi(cpu, prev_nmi_count);
 177         }
 178         endflag = 1;
 179         if (!nmi_usable) {
 180                 kfree(prev_nmi_count);
 181                 err = -ENODEV;
 182                 goto error;
 183         }
 184         printk("OK.\n");
 185
 186         nmi_hz = 1;
 187
 188         kfree(prev_nmi_count);
 189         return 0;
 190 error:
 191         on_each_cpu(stop_watchdog, NULL, 1);
 192         return err;
 193 }
 194
 195 static void start_watchdog(void *unused)
 196 {
 197         pcr_ops->write(PCR_PIC_PRIV);
 198         write_pic(picl_value(nmi_hz));
 199
 200         pcr_ops->write(pcr_enable);
 201 }
 202
 203 void nmi_adjust_hz(unsigned int new_hz)
 204 {
 205         nmi_hz = new_hz;
 206         on_each_cpu(start_watchdog, NULL, 1);
 207 }
 208 EXPORT_SYMBOL_GPL(nmi_adjust_hz);
 209
 210 static int nmi_shutdown(struct notifier_block *nb, unsigned long cmd, void *p)
 211 {
 212         on_each_cpu(stop_watchdog, NULL, 1);
 213         return 0;
 214 }
 215
 216 static struct notifier_block nmi_reboot_notifier = {
 217         .notifier_call = nmi_shutdown,
 218 };
 219
 220 int __init nmi_init(void)
 221 {
 222         int err;
 223
 224         nmi_usable = 1;
 225
 226         on_each_cpu(start_watchdog, NULL, 1);
 227
 228         err = check_nmi_watchdog();
 229         if (!err) {
 230                 err = register_reboot_notifier(&nmi_reboot_notifier);
 231                 if (err) {
 232                         nmi_usable = 0;
 233                         on_each_cpu(stop_watchdog, NULL, 1);
 234                 }
 235         }
 236         return err;
 237 }
 238
 239 static int __init setup_nmi_watchdog(char *str)
 240 {
 241         if (!strncmp(str, "panic", 5))
 242                 panic_on_timeout = 1;
 243
 244         return 0;
 245 }
 246 __setup("nmi_watchdog=", setup_nmi_watchdog);