// SPDX-License-Identifier: GPL-2.0 /* * Detect hard and soft lockups on a system * * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. * * Note: Most of this code is borrowed heavily from the original softlockup * detector, so thanks to Ingo for the initial implementation. * Some chunks also taken from the old x86-specific nmi watchdog code, thanks * to those contributors as well. */ #define pr_fmt(fmt) "watchdog: " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include "sched/sched.h" #include #include #include #include #include #include #ifdef CONFIG_SEC_DEBUG static const char * const hl_to_name[] = { "NONE", "TASK STUCK", "IRQ STUCK", "IDLE STUCK", "SMCCALL STUCK", "IRQ STORM", "HRTIMER ERROR", "UNKNOWN STUCK" }; static const char * const sl_to_name[] = { "NONE", "SOFTIRQ STUCK", "TASK STUCK", "UNKNOWN STUCK" }; #ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU static DEFINE_PER_CPU(struct hardlockup_info, percpu_hl_info); #endif #endif static DEFINE_MUTEX(watchdog_mutex); #if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HAVE_NMI_WATCHDOG) \ || defined(CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU) # define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED | NMI_WATCHDOG_ENABLED) # define NMI_WATCHDOG_DEFAULT 1 #else # define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED) # define NMI_WATCHDOG_DEFAULT 0 #endif unsigned long __read_mostly watchdog_enabled; int __read_mostly watchdog_user_enabled = 1; int __read_mostly nmi_watchdog_user_enabled = NMI_WATCHDOG_DEFAULT; int __read_mostly soft_watchdog_user_enabled = 1; int __read_mostly watchdog_thresh = 10; int __read_mostly nmi_watchdog_available; #if defined(CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU) int __read_mostly watchdog_other_cpu_available = WATCHDOG_DEFAULT; #endif struct cpumask watchdog_allowed_mask __read_mostly; struct cpumask watchdog_cpumask __read_mostly; unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask); #if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU) /* * Should we panic when a soft-lockup or hard-lockup occurs: */ unsigned int __read_mostly hardlockup_panic = CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE; /* * We may not want to enable hard lockup detection by default in all cases, * for example when running the kernel as a guest on a hypervisor. In these * cases this function can be called to disable hard lockup detection. This * function should only be executed once by the boot processor before the * kernel command line parameters are parsed, because otherwise it is not * possible to override this in hardlockup_panic_setup(). */ void __init hardlockup_detector_disable(void) { nmi_watchdog_user_enabled = 0; } static int __init hardlockup_panic_setup(char *str) { if (!strncmp(str, "panic", 5)) hardlockup_panic = 1; else if (!strncmp(str, "nopanic", 7)) hardlockup_panic = 0; else if (!strncmp(str, "0", 1)) nmi_watchdog_user_enabled = 0; else if (!strncmp(str, "1", 1)) nmi_watchdog_user_enabled = 1; return 1; } __setup("nmi_watchdog=", hardlockup_panic_setup); # ifdef CONFIG_SMP int __read_mostly sysctl_hardlockup_all_cpu_backtrace; static int __init hardlockup_all_cpu_backtrace_setup(char *str) { sysctl_hardlockup_all_cpu_backtrace = !!simple_strtol(str, NULL, 0); return 1; } __setup("hardlockup_all_cpu_backtrace=", hardlockup_all_cpu_backtrace_setup); # endif /* CONFIG_SMP */ #endif /* CONFIG_HARDLOCKUP_DETECTOR */ /* * These functions can be overridden if an architecture implements its * own hardlockup detector. * * watchdog_nmi_enable/disable can be implemented to start and stop when * softlockup watchdog threads start and stop. The arch must select the * SOFTLOCKUP_DETECTOR Kconfig. */ #ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU #ifdef CONFIG_SEC_DEBUG static void check_hardlockup_type(unsigned int cpu); #endif #else int __weak watchdog_nmi_enable(unsigned int cpu) { hardlockup_detector_perf_enable(); return 0; } void __weak watchdog_nmi_disable(unsigned int cpu) { hardlockup_detector_perf_disable(); } #endif /* Return 0, if a NMI watchdog is available. Error code otherwise */ int __weak __init watchdog_nmi_probe(void) { return hardlockup_detector_perf_init(); } /** * watchdog_nmi_stop - Stop the watchdog for reconfiguration * * The reconfiguration steps are: * watchdog_nmi_stop(); * update_variables(); * watchdog_nmi_start(); */ void __weak watchdog_nmi_stop(void) { } /** * watchdog_nmi_start - Start the watchdog after reconfiguration * * Counterpart to watchdog_nmi_stop(). * * The following variables have been updated in update_variables() and * contain the currently valid configuration: * - watchdog_enabled * - watchdog_thresh * - watchdog_cpumask */ void __weak watchdog_nmi_start(void) { } /** * lockup_detector_update_enable - Update the sysctl enable bit * * Caller needs to make sure that the NMI/perf watchdogs are off, so this * can't race with watchdog_nmi_disable(). */ static void lockup_detector_update_enable(void) { watchdog_enabled = 0; if (!watchdog_user_enabled) return; #if defined(CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU) if (watchdog_other_cpu_available && nmi_watchdog_user_enabled) watchdog_enabled |= NMI_WATCHDOG_ENABLED; #endif if (nmi_watchdog_available && nmi_watchdog_user_enabled) watchdog_enabled |= NMI_WATCHDOG_ENABLED; if (soft_watchdog_user_enabled) watchdog_enabled |= SOFT_WATCHDOG_ENABLED; } #ifdef CONFIG_SOFTLOCKUP_DETECTOR /* Global variables, exported for sysctl */ unsigned int __read_mostly softlockup_panic = CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE; static bool softlockup_threads_initialized __read_mostly; static u64 __read_mostly sample_period; static unsigned long __read_mostly hardlockup_thresh; static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts); static DEFINE_PER_CPU(unsigned long, hardlockup_touch_ts); static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog); static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer); static DEFINE_PER_CPU(bool, softlockup_touch_sync); static DEFINE_PER_CPU(bool, soft_watchdog_warn); static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved); static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); #ifdef CONFIG_SEC_DEBUG static DEFINE_PER_CPU(struct softlockup_info, percpu_sl_info); #endif static void check_softlockup_type(void); static unsigned long soft_lockup_nmi_warn; static int __init softlockup_panic_setup(char *str) { softlockup_panic = simple_strtoul(str, NULL, 0); return 1; } __setup("softlockup_panic=", softlockup_panic_setup); static int __init nowatchdog_setup(char *str) { watchdog_user_enabled = 0; return 1; } __setup("nowatchdog", nowatchdog_setup); static int __init nosoftlockup_setup(char *str) { soft_watchdog_user_enabled = 0; return 1; } __setup("nosoftlockup", nosoftlockup_setup); #ifdef CONFIG_SMP int __read_mostly sysctl_softlockup_all_cpu_backtrace; static int __init softlockup_all_cpu_backtrace_setup(char *str) { sysctl_softlockup_all_cpu_backtrace = !!simple_strtol(str, NULL, 0); return 1; } __setup("softlockup_all_cpu_backtrace=", softlockup_all_cpu_backtrace_setup); #endif static void __lockup_detector_cleanup(void); /* * Hard-lockup warnings should be triggered after just a few seconds. Soft- * lockups can have false positives under extreme conditions. So we generally * want a higher threshold for soft lockups than for hard lockups. So we couple * the thresholds with a factor: we make the soft threshold twice the amount of * time the hard threshold is. */ static int get_softlockup_thresh(void) { return watchdog_thresh * 2; } /* * Returns seconds, approximately. We don't need nanosecond * resolution, and we don't need to waste time with a big divide when * 2^30ns == 1.074s. */ static unsigned long get_timestamp(void) { return running_clock() >> 30LL; /* 2^30 ~= 10^9 */ } static void set_sample_period(void) { /* * convert watchdog_thresh from seconds to ns * the divide by 5 is to give hrtimer several chances (two * or three with the current relation between the soft * and hard thresholds) to increment before the * hardlockup detector generates a warning */ sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); watchdog_update_hrtimer_threshold(sample_period); hardlockup_thresh = sample_period * 3 / NSEC_PER_SEC; } /* Commands for resetting the watchdog */ static void __touch_watchdog(void) { __this_cpu_write(watchdog_touch_ts, get_timestamp()); __this_cpu_write(hardlockup_touch_ts, get_timestamp()); } /** * touch_softlockup_watchdog_sched - touch watchdog on scheduler stalls * * Call when the scheduler may have stalled for legitimate reasons * preventing the watchdog task from executing - e.g. the scheduler * entering idle state. This should only be used for scheduler events. * Use touch_softlockup_watchdog() for everything else. */ notrace void touch_softlockup_watchdog_sched(void) { /* * Preemption can be enabled. It doesn't matter which CPU's timestamp * gets zeroed here, so use the raw_ operation. */ raw_cpu_write(watchdog_touch_ts, 0); } notrace void touch_softlockup_watchdog(void) { touch_softlockup_watchdog_sched(); wq_watchdog_touch(raw_smp_processor_id()); } EXPORT_SYMBOL(touch_softlockup_watchdog); void touch_all_softlockup_watchdogs(void) { int cpu; /* * watchdog_mutex cannpt be taken here, as this might be called * from (soft)interrupt context, so the access to * watchdog_allowed_cpumask might race with a concurrent update. * * The watchdog time stamp can race against a concurrent real * update as well, the only side effect might be a cycle delay for * the softlockup check. */ for_each_cpu(cpu, &watchdog_allowed_mask) per_cpu(watchdog_touch_ts, cpu) = 0; wq_watchdog_touch(-1); } void touch_softlockup_watchdog_sync(void) { __this_cpu_write(softlockup_touch_sync, true); __this_cpu_write(watchdog_touch_ts, 0); } #ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU static void watchdog_check_hardlockup_other_cpu(void); #else static inline void watchdog_check_hardlockup_other_cpu(void) { return; } #endif static int is_softlockup(unsigned long touch_ts) { unsigned long now = get_timestamp(); if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){ /* Warn about unreasonable delays. */ if (time_after(now, touch_ts + get_softlockup_thresh())) return now - touch_ts; } return 0; } /* watchdog detector functions */ bool is_hardlockup(void) { unsigned long hrint = __this_cpu_read(hrtimer_interrupts); if (__this_cpu_read(hrtimer_interrupts_saved) == hrint) return true; __this_cpu_write(hrtimer_interrupts_saved, hrint); return false; } static void watchdog_interrupt_count(void) { __this_cpu_inc(hrtimer_interrupts); } /* watchdog kicker functions */ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) { unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts); struct pt_regs *regs = get_irq_regs(); int duration; int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace; /* try to enable log_kevent of exynos-snapshot if log_kevent was off because of rcu stall */ dbg_snapshot_try_enable("log_kevent", NSEC_PER_SEC * 15); if (!watchdog_enabled) return HRTIMER_NORESTART; /* kick the hardlockup detector */ watchdog_interrupt_count(); /* test for hardlockups on the next cpu */ watchdog_check_hardlockup_other_cpu(); /* kick the softlockup detector */ wake_up_process(__this_cpu_read(softlockup_watchdog)); /* .. and repeat */ hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); if (touch_ts == 0) { if (unlikely(__this_cpu_read(softlockup_touch_sync))) { /* * If the time stamp was touched atomically * make sure the scheduler tick is up to date. */ __this_cpu_write(softlockup_touch_sync, false); sched_clock_tick(); } /* Clear the guest paused flag on watchdog reset */ kvm_check_and_clear_guest_paused(); __touch_watchdog(); return HRTIMER_RESTART; } /* check for a softlockup * This is done by making sure a high priority task is * being scheduled. The task touches the watchdog to * indicate it is getting cpu time. If it hasn't then * this is a good indication some task is hogging the cpu */ duration = is_softlockup(touch_ts); if (unlikely(duration)) { /* * If a virtual machine is stopped by the host it can look to * the watchdog like a soft lockup, check to see if the host * stopped the vm before we issue the warning */ if (kvm_check_and_clear_guest_paused()) return HRTIMER_RESTART; /* only warn once */ if (__this_cpu_read(soft_watchdog_warn) == true) { /* * When multiple processes are causing softlockups the * softlockup detector only warns on the first one * because the code relies on a full quiet cycle to * re-arm. The second process prevents the quiet cycle * and never gets reported. Use task pointers to detect * this. */ if (__this_cpu_read(softlockup_task_ptr_saved) != current) { __this_cpu_write(soft_watchdog_warn, false); __touch_watchdog(); } return HRTIMER_RESTART; } if (softlockup_all_cpu_backtrace) { /* Prevent multiple soft-lockup reports if one cpu is already * engaged in dumping cpu back traces */ if (test_and_set_bit(0, &soft_lockup_nmi_warn)) { /* Someone else will report us. Let's give up */ __this_cpu_write(soft_watchdog_warn, true); return HRTIMER_RESTART; } } pr_auto(ASL9, "BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", smp_processor_id(), duration, current->comm, task_pid_nr(current)); #ifdef CONFIG_SEC_DEBUG check_softlockup_type(); #endif sec_debug_set_task_in_soft_lockup((uint64_t)current); sec_debug_set_cpu_in_soft_lockup((uint64_t)smp_processor_id()); __this_cpu_write(softlockup_task_ptr_saved, current); print_modules(); print_irqtrace_events(current); if (regs) #ifdef CONFIG_SEC_DEBUG_AUTO_COMMENT show_regs_auto_comment(regs, !!softlockup_panic); #else show_regs(regs); #endif else dump_stack(); if (softlockup_all_cpu_backtrace) { /* Avoid generating two back traces for current * given that one is already made above */ trigger_allbutself_cpu_backtrace(); clear_bit(0, &soft_lockup_nmi_warn); /* Barrier to sync with other cpus */ smp_mb__after_atomic(); } add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); if (softlockup_panic) { #ifdef CONFIG_SEC_DEBUG_EXTRA_INFO if (regs) { sec_debug_set_extra_info_fault(WATCHDOG_FAULT, (unsigned long)regs->pc, regs); sec_debug_set_extra_info_backtrace(regs); } #endif panic("softlockup: hung tasks"); } __this_cpu_write(soft_watchdog_warn, true); } else __this_cpu_write(soft_watchdog_warn, false); return HRTIMER_RESTART; } static void watchdog_set_prio(unsigned int policy, unsigned int prio) { struct sched_param param = { .sched_priority = prio }; sched_setscheduler(current, policy, ¶m); } static void watchdog_enable(unsigned int cpu) { struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer); /* * Start the timer first to prevent the NMI watchdog triggering * before the timer has a chance to fire. */ hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); hrtimer->function = watchdog_timer_fn; hrtimer_start(hrtimer, ns_to_ktime(sample_period), HRTIMER_MODE_REL_PINNED); /* Initialize timestamp */ __touch_watchdog(); /* Enable the perf event */ if (watchdog_enabled & NMI_WATCHDOG_ENABLED) watchdog_nmi_enable(cpu); watchdog_set_prio(SCHED_FIFO, MAX_RT_PRIO - 1); } static void watchdog_disable(unsigned int cpu) { struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer); watchdog_set_prio(SCHED_NORMAL, 0); /* * Disable the perf event first. That prevents that a large delay * between disabling the timer and disabling the perf event causes * the perf NMI to detect a false positive. */ watchdog_nmi_disable(cpu); hrtimer_cancel(hrtimer); } static void watchdog_cleanup(unsigned int cpu, bool online) { watchdog_disable(cpu); } static int watchdog_should_run(unsigned int cpu) { return __this_cpu_read(hrtimer_interrupts) != __this_cpu_read(soft_lockup_hrtimer_cnt); } /* * The watchdog thread function - touches the timestamp. * * It only runs once every sample_period seconds (4 seconds by * default) to reset the softlockup timestamp. If this gets delayed * for more than 2*watchdog_thresh seconds then the debug-printout * triggers in watchdog_timer_fn(). */ static void watchdog(unsigned int cpu) { __this_cpu_write(soft_lockup_hrtimer_cnt, __this_cpu_read(hrtimer_interrupts)); __touch_watchdog(); } static struct smp_hotplug_thread watchdog_threads = { .store = &softlockup_watchdog, .thread_should_run = watchdog_should_run, .thread_fn = watchdog, .thread_comm = "watchdog/%u", .setup = watchdog_enable, .cleanup = watchdog_cleanup, .park = watchdog_disable, .unpark = watchdog_enable, }; static void softlockup_update_smpboot_threads(void) { lockdep_assert_held(&watchdog_mutex); if (!softlockup_threads_initialized) return; smpboot_update_cpumask_percpu_thread(&watchdog_threads, &watchdog_allowed_mask); } /* Temporarily park all watchdog threads */ static void softlockup_park_all_threads(void) { cpumask_clear(&watchdog_allowed_mask); softlockup_update_smpboot_threads(); } /* Unpark enabled threads */ static void softlockup_unpark_threads(void) { cpumask_copy(&watchdog_allowed_mask, &watchdog_cpumask); softlockup_update_smpboot_threads(); } static void lockup_detector_reconfigure(void) { cpus_read_lock(); watchdog_nmi_stop(); softlockup_park_all_threads(); set_sample_period(); lockup_detector_update_enable(); if (watchdog_enabled && watchdog_thresh) softlockup_unpark_threads(); watchdog_nmi_start(); cpus_read_unlock(); /* * Must be called outside the cpus locked section to prevent * recursive locking in the perf code. */ __lockup_detector_cleanup(); } /* * Create the watchdog thread infrastructure and configure the detector(s). * * The threads are not unparked as watchdog_allowed_mask is empty. When * the threads are sucessfully initialized, take the proper locks and * unpark the threads in the watchdog_cpumask if the watchdog is enabled. */ static __init void lockup_detector_setup(void) { int ret; /* * If sysctl is off and watchdog got disabled on the command line, * nothing to do here. */ lockup_detector_update_enable(); if (!IS_ENABLED(CONFIG_SYSCTL) && !(watchdog_enabled && watchdog_thresh)) return; ret = smpboot_register_percpu_thread_cpumask(&watchdog_threads, &watchdog_allowed_mask); if (ret) { pr_err("Failed to initialize soft lockup detector threads\n"); return; } mutex_lock(&watchdog_mutex); softlockup_threads_initialized = true; lockup_detector_reconfigure(); mutex_unlock(&watchdog_mutex); } #ifdef CONFIG_SEC_DEBUG void sl_softirq_entry(const char *softirq_type, void *fn) { struct softlockup_info *sl_info = per_cpu_ptr(&percpu_sl_info, smp_processor_id()); if (softirq_type) { strncpy(sl_info->softirq_info.softirq_type, softirq_type, sizeof(sl_info->softirq_info.softirq_type) - 1); sl_info->softirq_info.softirq_type[SOFTIRQ_TYPE_LEN - 1] = '\0'; } sl_info->softirq_info.last_arrival = local_clock(); sl_info->softirq_info.fn = fn; } void sl_softirq_exit(void) { struct softlockup_info *sl_info = per_cpu_ptr(&percpu_sl_info, smp_processor_id()); sl_info->softirq_info.last_arrival = 0; sl_info->softirq_info.fn = (void *)0; sl_info->softirq_info.softirq_type[0] = '\0'; } void check_softlockup_type(void) { int cpu = smp_processor_id(); struct softlockup_info *sl_info = per_cpu_ptr(&percpu_sl_info, cpu); sl_info->preempt_count = preempt_count(); if (softirq_count() && sl_info->softirq_info.last_arrival != 0 && sl_info->softirq_info.fn != NULL) { sl_info->delay_time = local_clock() - sl_info->softirq_info.last_arrival; sl_info->sl_type = SL_SOFTIRQ_STUCK; pr_auto(ASL9, "Softlockup state: %s, Latency: %lluns, Softirq type: %s, Func: %pf, preempt_count : %x\n", sl_to_name[sl_info->sl_type], sl_info->delay_time, sl_info->softirq_info.softirq_type, sl_info->softirq_info.fn, sl_info->preempt_count); } else { dbg_snapshot_get_softlockup_info(cpu, sl_info); if (!(preempt_count() & PREEMPT_MASK) || softirq_count()) sl_info->sl_type = SL_UNKNOWN_STUCK; pr_auto(ASL9, "Softlockup state: %s, Latency: %lluns, Task: %s, preempt_count: %x\n", sl_to_name[sl_info->sl_type], sl_info->delay_time, sl_info->task_info.task_comm, sl_info->preempt_count); } } unsigned long long get_dss_softlockup_thresh(void) { return watchdog_thresh * 2 * NSEC_PER_SEC; } EXPORT_SYMBOL(get_dss_softlockup_thresh); #endif #else /* CONFIG_SOFTLOCKUP_DETECTOR */ static inline int watchdog_park_threads(void) { return 0; } static inline void watchdog_unpark_threads(void) { } static inline int watchdog_enable_all_cpus(void) { return 0; } static inline void watchdog_disable_all_cpus(void) { } static void lockup_detector_reconfigure(void) { cpus_read_lock(); watchdog_nmi_stop(); lockup_detector_update_enable(); watchdog_nmi_start(); cpus_read_unlock(); } static inline void lockup_detector_setup(void) { lockup_detector_reconfigure(); } #endif /* !CONFIG_SOFTLOCKUP_DETECTOR */ static void __lockup_detector_cleanup(void) { lockdep_assert_held(&watchdog_mutex); hardlockup_detector_perf_cleanup(); } /** * lockup_detector_cleanup - Cleanup after cpu hotplug or sysctl changes * * Caller must not hold the cpu hotplug rwsem. */ void lockup_detector_cleanup(void) { mutex_lock(&watchdog_mutex); __lockup_detector_cleanup(); mutex_unlock(&watchdog_mutex); } /** * lockup_detector_soft_poweroff - Interface to stop lockup detector(s) * * Special interface for parisc. It prevents lockup detector warnings from * the default pm_poweroff() function which busy loops forever. */ void lockup_detector_soft_poweroff(void) { watchdog_enabled = 0; } #ifdef CONFIG_SYSCTL /* Propagate any changes to the watchdog threads */ static void proc_watchdog_update(void) { /* Remove impossible cpus to keep sysctl output clean. */ cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask); lockup_detector_reconfigure(); } /* * common function for watchdog, nmi_watchdog and soft_watchdog parameter * * caller | table->data points to | 'which' * -------------------|----------------------------|-------------------------- * proc_watchdog | watchdog_user_enabled | NMI_WATCHDOG_ENABLED | * | | SOFT_WATCHDOG_ENABLED * -------------------|----------------------------|-------------------------- * proc_nmi_watchdog | nmi_watchdog_user_enabled | NMI_WATCHDOG_ENABLED * -------------------|----------------------------|-------------------------- * proc_soft_watchdog | soft_watchdog_user_enabled | SOFT_WATCHDOG_ENABLED */ static int proc_watchdog_common(int which, struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { int err, old, *param = table->data; mutex_lock(&watchdog_mutex); if (!write) { /* * On read synchronize the userspace interface. This is a * racy snapshot. */ *param = (watchdog_enabled & which) != 0; err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); } else { old = READ_ONCE(*param); err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); if (!err && old != READ_ONCE(*param)) proc_watchdog_update(); } mutex_unlock(&watchdog_mutex); return err; } /* * /proc/sys/kernel/watchdog */ int proc_watchdog(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED, table, write, buffer, lenp, ppos); } /* * /proc/sys/kernel/nmi_watchdog */ int proc_nmi_watchdog(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { if (!nmi_watchdog_available && write) return -ENOTSUPP; return proc_watchdog_common(NMI_WATCHDOG_ENABLED, table, write, buffer, lenp, ppos); } /* * /proc/sys/kernel/soft_watchdog */ int proc_soft_watchdog(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { return proc_watchdog_common(SOFT_WATCHDOG_ENABLED, table, write, buffer, lenp, ppos); } /* * /proc/sys/kernel/watchdog_thresh */ int proc_watchdog_thresh(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { int err, old; mutex_lock(&watchdog_mutex); old = READ_ONCE(watchdog_thresh); err = proc_dointvec_minmax(table, write, buffer, lenp, ppos); if (!err && write && old != READ_ONCE(watchdog_thresh)) proc_watchdog_update(); mutex_unlock(&watchdog_mutex); return err; } /* * The cpumask is the mask of possible cpus that the watchdog can run * on, not the mask of cpus it is actually running on. This allows the * user to specify a mask that will include cpus that have not yet * been brought online, if desired. */ int proc_watchdog_cpumask(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { int err; mutex_lock(&watchdog_mutex); err = proc_do_large_bitmap(table, write, buffer, lenp, ppos); if (!err && write) proc_watchdog_update(); mutex_unlock(&watchdog_mutex); return err; } #endif /* CONFIG_SYSCTL */ void __init lockup_detector_init(void) { #ifdef CONFIG_NO_HZ_FULL if (tick_nohz_full_enabled()) { pr_info("Disabling watchdog on nohz_full cores by default\n"); cpumask_copy(&watchdog_cpumask, housekeeping_mask); } else cpumask_copy(&watchdog_cpumask, cpu_possible_mask); #else cpumask_copy(&watchdog_cpumask, cpu_possible_mask); #endif if (!watchdog_nmi_probe()) nmi_watchdog_available = true; lockup_detector_setup(); } #ifdef CONFIG_HARDLOCKUP_DETECTOR_OTHER_CPU static DEFINE_PER_CPU(bool, hard_watchdog_warn); static DEFINE_PER_CPU(bool, watchdog_nmi_touch); static cpumask_t __read_mostly watchdog_cpus; ATOMIC_NOTIFIER_HEAD(hardlockup_notifier_list); EXPORT_SYMBOL(hardlockup_notifier_list); static unsigned int watchdog_next_cpu(unsigned int cpu) { cpumask_t cpus = watchdog_cpus; unsigned int next_cpu; next_cpu = cpumask_next(cpu, &cpus); if (next_cpu >= nr_cpu_ids) next_cpu = cpumask_first(&cpus); if (next_cpu == cpu) return nr_cpu_ids; return next_cpu; } static int is_hardlockup_other_cpu(unsigned int cpu) { unsigned long hrint = per_cpu(hrtimer_interrupts, cpu); if (per_cpu(hrtimer_interrupts_saved, cpu) == hrint) { unsigned long now = get_timestamp(); unsigned long touch_ts = per_cpu(hardlockup_touch_ts, cpu); if (time_after(now, touch_ts) && (now - touch_ts >= hardlockup_thresh)) return 1; } per_cpu(hrtimer_interrupts_saved, cpu) = hrint; return 0; } static void watchdog_check_hardlockup_other_cpu(void) { unsigned int next_cpu; /* * Test for hardlockups every 3 samples. The sample period is * watchdog_thresh * 2 / 5, so 3 samples gets us back to slightly over * watchdog_thresh (over by 20%). */ if (__this_cpu_read(hrtimer_interrupts) % 3 != 0) return; /* check for a hardlockup on the next cpu */ next_cpu = watchdog_next_cpu(smp_processor_id()); if (next_cpu >= nr_cpu_ids) return; smp_rmb(); if (per_cpu(watchdog_nmi_touch, next_cpu) == true) { per_cpu(watchdog_nmi_touch, next_cpu) = false; return; } if (is_hardlockup_other_cpu(next_cpu)) { #ifdef CONFIG_SEC_DEBUG check_hardlockup_type(next_cpu); #endif /* only warn once */ if (per_cpu(hard_watchdog_warn, next_cpu) == true) return; if (hardlockup_panic) { dbg_snapshot_set_hardlockup(hardlockup_panic); atomic_notifier_call_chain(&hardlockup_notifier_list, 0, (void *)&next_cpu); sec_debug_set_cpu_in_hard_lockup((uint64_t)next_cpu); sec_debug_set_task_in_hard_lockup((uint64_t)((struct rq *)cpu_rq(next_cpu)->curr)); panic("Watchdog detected hard LOCKUP on cpu %u", next_cpu); } else { WARN(1, "Watchdog detected hard LOCKUP on cpu %u", next_cpu); } per_cpu(hard_watchdog_warn, next_cpu) = true; } else { per_cpu(hard_watchdog_warn, next_cpu) = false; } } void touch_nmi_watchdog(void) { /* * Using __raw here because some code paths have * preemption enabled. If preemption is enabled * then interrupts should be enabled too, in which * case we shouldn't have to worry about the watchdog * going off. */ raw_cpu_write(watchdog_nmi_touch, true); arch_touch_nmi_watchdog(); touch_softlockup_watchdog(); } EXPORT_SYMBOL(touch_nmi_watchdog); int watchdog_nmi_enable(unsigned int cpu) { /* * The new cpu will be marked online before the first hrtimer interrupt * runs on it. If another cpu tests for a hardlockup on the new cpu * before it has run its first hrtimer, it will get a false positive. * Touch the watchdog on the new cpu to delay the first check for at * least 3 sampling periods to guarantee one hrtimer has run on the new * cpu. */ per_cpu(watchdog_nmi_touch, cpu) = true; smp_wmb(); cpumask_set_cpu(cpu, &watchdog_cpus); return 0; } void watchdog_nmi_disable(unsigned int cpu) { unsigned int next_cpu = watchdog_next_cpu(cpu); /* * Offlining this cpu will cause the cpu before this one to start * checking the one after this one. If this cpu just finished checking * the next cpu and updating hrtimer_interrupts_saved, and then the * previous cpu checks it within one sample period, it will trigger a * false positive. Touch the watchdog on the next cpu to prevent it. */ if (next_cpu < nr_cpu_ids) per_cpu(watchdog_nmi_touch, next_cpu) = true; smp_wmb(); cpumask_clear_cpu(cpu, &watchdog_cpus); } #ifdef CONFIG_SEC_DEBUG static void check_hardlockup_type(unsigned int cpu) { struct hardlockup_info *hl_info = per_cpu_ptr(&percpu_hl_info, cpu); dbg_snapshot_get_hardlockup_info(cpu, hl_info); if (hl_info->hl_type == HL_TASK_STUCK) { pr_auto(ASL9, "Hardlockup state: %s, Latency: %lluns, TASK: %s\n", hl_to_name[hl_info->hl_type], hl_info->delay_time, hl_info->task_info.task_comm); } else if (hl_info->hl_type == HL_IRQ_STUCK) { pr_auto(ASL9, "Hardlockup state: %s, Latency: %lluns, IRQ: %d, Func: %pf\n", hl_to_name[hl_info->hl_type], hl_info->delay_time, hl_info->irq_info.irq, hl_info->irq_info.fn); } else if (hl_info->hl_type == HL_IDLE_STUCK) { pr_auto(ASL9, "Hardlockup state: %s, Latency: %lluns, mode: %s\n", hl_to_name[hl_info->hl_type], hl_info->delay_time, hl_info->cpuidle_info.mode); } else if (hl_info->hl_type == HL_SMC_CALL_STUCK) { pr_auto(ASL9, "Hardlockup state: %s, Latency: %lluns, CMD: %u\n", hl_to_name[hl_info->hl_type], hl_info->delay_time, hl_info->smc_info.cmd); } else if (hl_info->hl_type == HL_IRQ_STORM) { pr_auto(ASL9, "Hardlockup state: %s, Latency: %lluns, IRQ : %d, Func: %pf, Avg period: %lluns\n", hl_to_name[hl_info->hl_type], hl_info->delay_time, hl_info->irq_info.irq, hl_info->irq_info.fn, hl_info->irq_info.avg_period); } else if (hl_info->hl_type == HL_UNKNOWN_STUCK) { pr_auto(ASL9, "Hardlockup state: %s, Latency: %lluns, TASK: %s\n", hl_to_name[hl_info->hl_type], hl_info->delay_time, hl_info->task_info.task_comm); } } void update_hardlockup_type(unsigned int cpu) { struct hardlockup_info *hl_info = per_cpu_ptr(&percpu_hl_info, cpu); if (hl_info->hl_type == HL_TASK_STUCK && !irqs_disabled()) { hl_info->hl_type = HL_UNKNOWN_STUCK; pr_info("Unknown stuck because IRQ was enabled but IRQ was not generated\n"); } } EXPORT_SYMBOL(update_hardlockup_type); unsigned long long get_hardlockup_thresh(void) { return (hardlockup_thresh * NSEC_PER_SEC - sample_period); } EXPORT_SYMBOL(get_hardlockup_thresh); #endif #endif