kernel/watchdog.c

   1 /*
   2  * This is arch independent NMI watchdog implementation part. It is used to
   3  * detect kernel lockups and help debugging. each architecture must add its own
   4  * low level code that triggers periodic checks
   5  */
   6
   7 #include "watchdog.h"
   8 #include "arch/i386/glo.h"
   9 #include "profile.h"
  10
  11 unsigned watchdog_local_timer_ticks = 0U;
  12 struct arch_watchdog *watchdog;
  13 int watchdog_enabled;
  14
  15 static void lockup_check(struct nmi_frame * frame)
  16 {
  17         /* FIXME this should be CPU local */
  18         static unsigned no_ticks;
  19         static unsigned last_tick_count = (unsigned) -1;
  20
  21         /*
  22          * when debugging on serial console, printing takes a lot of time some
  23          * times while the kernel is certainly not locked up. We don't want to
  24          * report a lockup in such situation
  25          */
  26         if (serial_debug_active)
  27                 return;
  28
  29         if (last_tick_count != watchdog_local_timer_ticks) {
  30                 if (no_ticks == 1) {
  31                         printf("watchdog : kernel unlocked\n");
  32                         no_ticks = 0;
  33                 }
  34                 /* we are still ticking, everything seems good */
  35                 last_tick_count = watchdog_local_timer_ticks;
  36                 return;
  37         }
  38
  39         /*
  40          * if watchdog_local_timer_ticks didn't changed since last time, give it
  41          * some more time and only if it still dead, trigger the watchdog alarm
  42          */
  43         if (++no_ticks < 10) {
  44                 if (no_ticks == 1)
  45                         printf("WARNING watchdog : possible kernel lockup\n");
  46                 return;
  47         }
  48
  49         /* if we get this far, the kernel is locked up */
  50         arch_watchdog_lockup(frame);
  51 }
  52
  53 void nmi_watchdog_handler(struct nmi_frame * frame)
  54 {
  55 #if SPROFILE
  56         /*
  57          * Do not check for lockups while profiling, it is extremely likely that
  58          * a false positive is detected if the frequency is high
  59          */
  60         if (watchdog_enabled && !sprofiling)
  61                 lockup_check(frame);
  62         if (sprofiling)
  63                 nmi_sprofile_handler(frame);
  64
  65         if ((watchdog_enabled || sprofiling) && watchdog->reinit)
  66                 watchdog->reinit(cpuid);
  67 #else
  68         if (watchdog_enabled) {
  69                 lockup_check(frame);
  70                 if (watchdog->reinit)
  71                         watchdog->reinit(cpuid);
  72         }
  73 #endif
  74 }
  75
  76 int nmi_watchdog_start_profiling(const unsigned freq)
  77 {
  78         int err;
  79
  80         /* if watchdog hasn't been enabled, we must enable it now */
  81         if (!watchdog_enabled) {
  82                 if (arch_watchdog_init())
  83                         return ENODEV;
  84         }
  85
  86         if (!watchdog->profile_init) {
  87                 printf("WARNING NMI watchdog profiling not supported\n");
  88                 nmi_watchdog_stop_profiling();
  89                 return ENODEV;
  90         }
  91
  92         err = watchdog->profile_init(freq);
  93         if (err != OK)
  94                 return err;
  95
  96         watchdog->resetval = watchdog->profile_resetval;
  97
  98         return OK;
  99 }
 100
 101 void nmi_watchdog_stop_profiling(void)
 102 {
 103         /*
 104          * if we do not rearm the NMI source, we are done, if we want to keep
 105          * the watchdog running, we reset is to its normal value
 106          */
 107
 108         if (watchdog)
 109                 watchdog->resetval = watchdog->watchdog_resetval;
 110
 111         if (!watchdog_enabled)
 112                 arch_watchdog_stop();
 113 }