e63b85a50b
- if profile --nmi kernel uses NMI watchdog based sampling based on Intel architecture performance counters - using NMI makes kernel profiling possible - watchdog kernel lockup detection is disabled while sampling as we may get unpredictable interrupts in kernel and thus possibly many false positives - if watchdog is not enabled at boot time, profiling enables it and turns it of again when done
105 lines
2.5 KiB
C
105 lines
2.5 KiB
C
/*
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* This is arch independent NMI watchdog implementaion part. It is used to
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* detect kernel lockups and help debugging. each architecture must add its own
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* low level code that triggers periodic checks
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*/
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#include "watchdog.h"
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#include "arch/i386/glo.h"
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#include "profile.h"
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unsigned watchdog_local_timer_ticks = 0U;
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struct arch_watchdog *watchdog;
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int watchdog_enabled;
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PRIVATE void lockup_check(struct nmi_frame * frame)
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{
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/* FIXME this should be CPU local */
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static unsigned no_ticks;
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static unsigned last_tick_count = (unsigned) -1;
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/*
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* when debugging on serial console, printing takes a lot of time some
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* times while the kernel is certainly not locked up. We don't want to
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* report a lockup in such situation
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*/
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if (serial_debug_active)
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return;
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if (last_tick_count != watchdog_local_timer_ticks) {
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if (no_ticks == 1) {
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printf("watchdog : kernel unlocked\n");
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no_ticks = 0;
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}
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/* we are still ticking, everything seems good */
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last_tick_count = watchdog_local_timer_ticks;
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return;
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}
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/*
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* if watchdog_local_timer_ticks didn't changed since last time, give it
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* some more time and only if it still dead, trigger the watchdog alarm
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*/
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if (++no_ticks < 10) {
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if (no_ticks == 1)
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printf("WARNING watchdog : possible kernel lockup\n");
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return;
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}
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/* if we get this far, the kernel is locked up */
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arch_watchdog_lockup(frame);
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}
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PUBLIC void nmi_watchdog_handler(struct nmi_frame * frame)
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{
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/*
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* Do not check for lockups while profiling, it is extremely likely that
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* a false positive is detected if the frequency is high
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*/
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if (watchdog_enabled && !sprofiling)
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lockup_check(frame);
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if (sprofiling)
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nmi_sprofile_handler(frame);
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if ((watchdog_enabled || sprofiling) && watchdog->reinit)
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watchdog->reinit(cpuid);
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}
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int nmi_watchdog_start_profiling(const unsigned freq)
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{
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int err;
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/* if watchdog hasn't been enabled, we must enable it now */
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if (!watchdog_enabled) {
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if (arch_watchdog_init())
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return ENODEV;
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}
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if (!watchdog->profile_init) {
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printf("WARNING NMI watchdog profiling not supported\n");
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nmi_watchdog_stop_profiling();
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return ENODEV;
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}
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err = watchdog->profile_init(freq);
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if (err != OK)
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return err;
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watchdog->resetval = watchdog->profile_resetval;
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return OK;
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}
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void nmi_watchdog_stop_profiling(void)
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{
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/*
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* if we do not rearm the NMI source, we are done, if we want to keep
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* the watchdog running, we reset is to its normal value
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*/
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if (watchdog)
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watchdog->resetval = watchdog->watchdog_resetval;
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if (!watchdog_enabled)
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arch_watchdog_stop();
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}
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