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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/slab.h>
  17 #include <linux/kdebug.h>
  18 #include <linux/delay.h>
  19 #include <linux/smp.h>
  20
  21 #include <asm/ptrace.h>
  22 #include <asm/local.h>
  23 #include <asm/pcr.h>
  24
  25 /* We don't have a real NMI on sparc64, but we can fake one
  26  * up using profiling counter overflow interrupts and interrupt
  27  * levels.
  28  *
  29  * The profile overflow interrupts at level 15, so we use
  30  * level 14 as our IRQ off level.
  31  */
  32
  33 static int nmi_watchdog_active;
  34 static int panic_on_timeout;
  35
  36 int nmi_usable;
  37 EXPORT_SYMBOL_GPL(nmi_usable);
  38
  39 static unsigned int nmi_hz = HZ;
  40
  41 static DEFINE_PER_CPU(unsigned int, last_irq_sum);
  42 static DEFINE_PER_CPU(local_t, alert_counter);
  43 static DEFINE_PER_CPU(int, nmi_touch);
  44
  45 void touch_nmi_watchdog(void)
  46 {
  47         if (nmi_watchdog_active) {
  48                 int cpu;
  49
  50                 for_each_present_cpu(cpu) {
  51                         if (per_cpu(nmi_touch, cpu) != 1)
  52                                 per_cpu(nmi_touch, cpu) = 1;
  53                 }
  54         }
  55
  56         touch_softlockup_watchdog();
  57 }
  58 EXPORT_SYMBOL(touch_nmi_watchdog);
  59
  60 static void die_nmi(const char *str, struct pt_regs *regs, int do_panic)
  61 {
  62         if (notify_die(DIE_NMIWATCHDOG, str, regs, 0,
  63                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
  64                 return;
  65
  66         console_verbose();
  67         bust_spinlocks(1);
  68
  69         printk(KERN_EMERG "%s", str);
  70         printk(" on CPU%d, ip %08lx, registers:\n",
  71                smp_processor_id(), regs->tpc);
  72         show_regs(regs);
  73
  74         bust_spinlocks(0);
  75
  76         if (do_panic || panic_on_oops)
  77                 panic("Non maskable interrupt");
  78
  79         local_irq_enable();
  80         do_exit(SIGBUS);
  81 }
  82
  83 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
  84 {
  85         unsigned int sum, touched = 0;
  86         int cpu = smp_processor_id();
  87
  88         clear_softint(1 << irq);
  89         pcr_ops->write(PCR_PIC_PRIV);
  90
  91         local_cpu_data().__nmi_count++;
  92
  93         if (notify_die(DIE_NMI, "nmi", regs, 0,
  94                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
  95                 touched = 1;
  96
  97         sum = kstat_irqs_cpu(0, cpu);
  98         if (__get_cpu_var(nmi_touch)) {
  99                 __get_cpu_var(nmi_touch) = 0;
 100                 touched = 1;
 101         }
 102         if (!touched && __get_cpu_var(last_irq_sum) == sum) {
 103                 local_inc(&__get_cpu_var(alert_counter));
 104                 if (local_read(&__get_cpu_var(alert_counter)) == 5 * nmi_hz)
 105                         die_nmi("BUG: NMI Watchdog detected LOCKUP",
 106                                 regs, panic_on_timeout);
 107         } else {
 108                 __get_cpu_var(last_irq_sum) = sum;
 109                 local_set(&__get_cpu_var(alert_counter), 0);
 110         }
 111         if (nmi_usable) {
 112                 write_pic(picl_value(nmi_hz));
 113                 pcr_ops->write(pcr_enable);
 114         }
 115 }
 116
 117 static inline unsigned int get_nmi_count(int cpu)
 118 {
 119         return cpu_data(cpu).__nmi_count;
 120 }
 121
 122 static int endflag __initdata;
 123
 124 static __init void nmi_cpu_busy(void *data)
 125 {
 126         local_irq_enable_in_hardirq();
 127         while (endflag == 0)
 128                 mb();
 129 }
 130
 131 static void report_broken_nmi(int cpu, int *prev_nmi_count)
 132 {
 133         printk(KERN_CONT "\n");
 134
 135         printk(KERN_WARNING
 136                 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
 137                         cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
 138
 139         printk(KERN_WARNING
 140                 "Please report this to bugzilla.kernel.org,\n");
 141         printk(KERN_WARNING
 142                 "and attach the output of the 'dmesg' command.\n");
 143
 144         nmi_usable = 0;
 145 }
 146
 147 static void stop_watchdog(void *unused)
 148 {
 149         pcr_ops->write(PCR_PIC_PRIV);
 150 }
 151
 152 static int __init check_nmi_watchdog(void)
 153 {
 154         unsigned int *prev_nmi_count;
 155         int cpu, err;
 156
 157         prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
 158         if (!prev_nmi_count) {
 159                 err = -ENOMEM;
 160                 goto error;
 161         }
 162
 163         printk(KERN_INFO "Testing NMI watchdog ... ");
 164
 165         smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
 166
 167         for_each_possible_cpu(cpu)
 168                 prev_nmi_count[cpu] = get_nmi_count(cpu);
 169         local_irq_enable();
 170         mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
 171
 172         for_each_online_cpu(cpu) {
 173                 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
 174                         report_broken_nmi(cpu, prev_nmi_count);
 175         }
 176         endflag = 1;
 177         if (!nmi_usable) {
 178                 kfree(prev_nmi_count);
 179                 err = -ENODEV;
 180                 goto error;
 181         }
 182         printk("OK.\n");
 183
 184         nmi_hz = 1;
 185
 186         kfree(prev_nmi_count);
 187         return 0;
 188 error:
 189         on_each_cpu(stop_watchdog, NULL, 1);
 190         return err;
 191 }
 192
 193 static void start_watchdog(void *unused)
 194 {
 195         pcr_ops->write(PCR_PIC_PRIV);
 196         write_pic(picl_value(nmi_hz));
 197
 198         pcr_ops->write(pcr_enable);
 199 }
 200
 201 void nmi_adjust_hz(unsigned int new_hz)
 202 {
 203         nmi_hz = new_hz;
 204         on_each_cpu(start_watchdog, NULL, 1);
 205 }
 206 EXPORT_SYMBOL_GPL(nmi_adjust_hz);
 207
 208 int __init nmi_init(void)
 209 {
 210         nmi_usable = 1;
 211
 212         on_each_cpu(start_watchdog, NULL, 1);
 213
 214         return check_nmi_watchdog();
 215 }
 216
 217 static int __init setup_nmi_watchdog(char *str)
 218 {
 219         if (!strncmp(str, "panic", 5))
 220                 panic_on_timeout = 1;
 221
 222         return 0;
 223 }
 224 __setup("nmi_watchdog=", setup_nmi_watchdog);