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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         dump_stack();
  74
  75         bust_spinlocks(0);
  76
  77         if (do_panic || panic_on_oops)
  78                 panic("Non maskable interrupt");
  79
  80         local_irq_enable();
  81         do_exit(SIGBUS);
  82 }
  83
  84 notrace __kprobes void perfctr_irq(int irq, struct pt_regs *regs)
  85 {
  86         unsigned int sum, touched = 0;
  87         int cpu = smp_processor_id();
  88
  89         clear_softint(1 << irq);
  90         pcr_ops->write(PCR_PIC_PRIV);
  91
  92         local_cpu_data().__nmi_count++;
  93
  94         if (notify_die(DIE_NMI, "nmi", regs, 0,
  95                        pt_regs_trap_type(regs), SIGINT) == NOTIFY_STOP)
  96                 touched = 1;
  97
  98         sum = kstat_irqs_cpu(0, cpu);
  99         if (__get_cpu_var(nmi_touch)) {
 100                 __get_cpu_var(nmi_touch) = 0;
 101                 touched = 1;
 102         }
 103         if (!touched && __get_cpu_var(last_irq_sum) == sum) {
 104                 local_inc(&__get_cpu_var(alert_counter));
 105                 if (local_read(&__get_cpu_var(alert_counter)) == 5 * nmi_hz)
 106                         die_nmi("BUG: NMI Watchdog detected LOCKUP",
 107                                 regs, panic_on_timeout);
 108         } else {
 109                 __get_cpu_var(last_irq_sum) = sum;
 110                 local_set(&__get_cpu_var(alert_counter), 0);
 111         }
 112         if (nmi_usable) {
 113                 write_pic(picl_value(nmi_hz));
 114                 pcr_ops->write(pcr_enable);
 115         }
 116 }
 117
 118 static inline unsigned int get_nmi_count(int cpu)
 119 {
 120         return cpu_data(cpu).__nmi_count;
 121 }
 122
 123 static int endflag __initdata;
 124
 125 static __init void nmi_cpu_busy(void *data)
 126 {
 127         local_irq_enable_in_hardirq();
 128         while (endflag == 0)
 129                 mb();
 130 }
 131
 132 static void report_broken_nmi(int cpu, int *prev_nmi_count)
 133 {
 134         printk(KERN_CONT "\n");
 135
 136         printk(KERN_WARNING
 137                 "WARNING: CPU#%d: NMI appears to be stuck (%d->%d)!\n",
 138                         cpu, prev_nmi_count[cpu], get_nmi_count(cpu));
 139
 140         printk(KERN_WARNING
 141                 "Please report this to bugzilla.kernel.org,\n");
 142         printk(KERN_WARNING
 143                 "and attach the output of the 'dmesg' command.\n");
 144
 145         nmi_usable = 0;
 146 }
 147
 148 static void stop_watchdog(void *unused)
 149 {
 150         pcr_ops->write(PCR_PIC_PRIV);
 151 }
 152
 153 static int __init check_nmi_watchdog(void)
 154 {
 155         unsigned int *prev_nmi_count;
 156         int cpu, err;
 157
 158         prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(unsigned int), GFP_KERNEL);
 159         if (!prev_nmi_count) {
 160                 err = -ENOMEM;
 161                 goto error;
 162         }
 163
 164         printk(KERN_INFO "Testing NMI watchdog ... ");
 165
 166         smp_call_function(nmi_cpu_busy, (void *)&endflag, 0);
 167
 168         for_each_possible_cpu(cpu)
 169                 prev_nmi_count[cpu] = get_nmi_count(cpu);
 170         local_irq_enable();
 171         mdelay((20 * 1000) / nmi_hz); /* wait 20 ticks */
 172
 173         for_each_online_cpu(cpu) {
 174                 if (get_nmi_count(cpu) - prev_nmi_count[cpu] <= 5)
 175                         report_broken_nmi(cpu, prev_nmi_count);
 176         }
 177         endflag = 1;
 178         if (!nmi_usable) {
 179                 kfree(prev_nmi_count);
 180                 err = -ENODEV;
 181                 goto error;
 182         }
 183         printk("OK.\n");
 184
 185         nmi_hz = 1;
 186
 187         kfree(prev_nmi_count);
 188         return 0;
 189 error:
 190         on_each_cpu(stop_watchdog, NULL, 1);
 191         return err;
 192 }
 193
 194 static void start_watchdog(void *unused)
 195 {
 196         pcr_ops->write(PCR_PIC_PRIV);
 197         write_pic(picl_value(nmi_hz));
 198
 199         pcr_ops->write(pcr_enable);
 200 }
 201
 202 void nmi_adjust_hz(unsigned int new_hz)
 203 {
 204         nmi_hz = new_hz;
 205         on_each_cpu(start_watchdog, NULL, 1);
 206 }
 207 EXPORT_SYMBOL_GPL(nmi_adjust_hz);
 208
 209 int __init nmi_init(void)
 210 {
 211         nmi_usable = 1;
 212
 213         on_each_cpu(start_watchdog, NULL, 1);
 214
 215         return check_nmi_watchdog();
 216 }
 217
 218 static int __init setup_nmi_watchdog(char *str)
 219 {
 220         if (!strncmp(str, "panic", 5))
 221                 panic_on_timeout = 1;
 222
 223         return 0;
 224 }
 225 __setup("nmi_watchdog=", setup_nmi_watchdog);