/* * linux/kernel/panic.c * * Copyright (C) 1991, 1992 Linus Torvalds */ /* * This function is used through-out the kernel (including mm and fs) * to indicate a major problem. */ #include <linux/debug_locks.h> #include <linux/interrupt.h> #include <linux/kmsg_dump.h> #include <linux/kallsyms.h> #include <linux/notifier.h> #include <linux/module.h> #include <linux/random.h> #include <linux/ftrace.h> #include <linux/reboot.h> #include <linux/delay.h> #include <linux/kexec.h> #include <linux/sched.h> #include <linux/sysrq.h> #include <linux/init.h> #include <linux/nmi.h> #define PANIC_TIMER_STEP 100 #define PANIC_BLINK_SPD 18 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE; static unsigned long tainted_mask; static int pause_on_oops; static int pause_on_oops_flag; static DEFINE_SPINLOCK(pause_on_oops_lock); static bool crash_kexec_post_notifiers; int panic_on_warn __read_mostly; int panic_timeout = CONFIG_PANIC_TIMEOUT; EXPORT_SYMBOL_GPL(panic_timeout); ATOMIC_NOTIFIER_HEAD(panic_notifier_list); EXPORT_SYMBOL(panic_notifier_list); static long no_blink(int state) { return 0; } /* Returns how long it waited in ms */ long (*panic_blink)(int state); EXPORT_SYMBOL(panic_blink); /* * Stop ourself in panic -- architecture code may override this */ void __weak panic_smp_self_stop(void) { while (1) cpu_relax(); } /** * panic - halt the system * @fmt: The text string to print * * Display a message, then perform cleanups. * * This function never returns. */ void panic(const char *fmt, ...) { static DEFINE_SPINLOCK(panic_lock); static char buf[1024]; va_list args; long i, i_next = 0; int state = 0; /* * Disable local interrupts. This will prevent panic_smp_self_stop * from deadlocking the first cpu that invokes the panic, since * there is nothing to prevent an interrupt handler (that runs * after the panic_lock is acquired) from invoking panic again. */ local_irq_disable(); /* * It's possible to come here directly from a panic-assertion and * not have preempt disabled. Some functions called from here want * preempt to be disabled. No point enabling it later though... * * Only one CPU is allowed to execute the panic code from here. For * multiple parallel invocations of panic, all other CPUs either * stop themself or will wait until they are stopped by the 1st CPU * with smp_send_stop(). */ if (!spin_trylock(&panic_lock)) panic_smp_self_stop(); console_verbose(); bust_spinlocks(1); va_start(args, fmt); vsnprintf(buf, sizeof(buf), fmt, args); va_end(args); pr_emerg("Kernel panic - not syncing: %s\n", buf); #ifdef CONFIG_DEBUG_BUGVERBOSE /* * Avoid nested stack-dumping if a panic occurs during oops processing */ if (!test_taint(TAINT_DIE) && oops_in_progress <= 1) dump_stack(); #endif /* * If we have crashed and we have a crash kernel loaded let it handle * everything else. * If we want to run this after calling panic_notifiers, pass * the "crash_kexec_post_notifiers" option to the kernel. */ if (!crash_kexec_post_notifiers) crash_kexec(NULL); /* * Note smp_send_stop is the usual smp shutdown function, which * unfortunately means it may not be hardened to work in a panic * situation. */ smp_send_stop(); /* * Run any panic handlers, including those that might need to * add information to the kmsg dump output. */ atomic_notifier_call_chain(&panic_notifier_list, 0, buf); kmsg_dump(KMSG_DUMP_PANIC); /* * If you doubt kdump always works fine in any situation, * "crash_kexec_post_notifiers" offers you a chance to run * panic_notifiers and dumping kmsg before kdump. * Note: since some panic_notifiers can make crashed kernel * more unstable, it can increase risks of the kdump failure too. */ crash_kexec(NULL); bust_spinlocks(0); if (!panic_blink) panic_blink = no_blink; if (panic_timeout > 0) { /* * Delay timeout seconds before rebooting the machine. * We can't use the "normal" timers since we just panicked. */ pr_emerg("Rebooting in %d seconds..", panic_timeout); for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { touch_nmi_watchdog(); if (i >= i_next) { i += panic_blink(state ^= 1); i_next = i + 3600 / PANIC_BLINK_SPD; } mdelay(PANIC_TIMER_STEP); } } if (panic_timeout != 0) { /* * This will not be a clean reboot, with everything * shutting down. But if there is a chance of * rebooting the system it will be rebooted. */ emergency_restart(); } #ifdef __sparc__ { extern int stop_a_enabled; /* Make sure the user can actually press Stop-A (L1-A) */ stop_a_enabled = 1; pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n"); } #endif #if defined(CONFIG_S390) { unsigned long caller; caller = (unsigned long)__builtin_return_address(0); disabled_wait(caller); } #endif pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf); local_irq_enable(); for (i = 0; ; i += PANIC_TIMER_STEP) { touch_softlockup_watchdog(); if (i >= i_next) { i += panic_blink(state ^= 1); i_next = i + 3600 / PANIC_BLINK_SPD; } mdelay(PANIC_TIMER_STEP); } } EXPORT_SYMBOL(panic); struct tnt { u8 bit; char true; char false; }; static const struct tnt tnts[] = { { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, { TAINT_FORCED_MODULE, 'F', ' ' }, { TAINT_CPU_OUT_OF_SPEC, 'S', ' ' }, { TAINT_FORCED_RMMOD, 'R', ' ' }, { TAINT_MACHINE_CHECK, 'M', ' ' }, { TAINT_BAD_PAGE, 'B', ' ' }, { TAINT_USER, 'U', ' ' }, { TAINT_DIE, 'D', ' ' }, { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, { TAINT_WARN, 'W', ' ' }, { TAINT_CRAP, 'C', ' ' }, { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' }, { TAINT_OOT_MODULE, 'O', ' ' }, { TAINT_UNSIGNED_MODULE, 'E', ' ' }, { TAINT_SOFTLOCKUP, 'L', ' ' }, }; /** * print_tainted - return a string to represent the kernel taint state. * * 'P' - Proprietary module has been loaded. * 'F' - Module has been forcibly loaded. * 'S' - SMP with CPUs not designed for SMP. * 'R' - User forced a module unload. * 'M' - System experienced a machine check exception. * 'B' - System has hit bad_page. * 'U' - Userspace-defined naughtiness. * 'D' - Kernel has oopsed before * 'A' - ACPI table overridden. * 'W' - Taint on warning. * 'C' - modules from drivers/staging are loaded. * 'I' - Working around severe firmware bug. * 'O' - Out-of-tree module has been loaded. * 'E' - Unsigned module has been loaded. * 'L' - A soft lockup has previously occurred. * * The string is overwritten by the next call to print_tainted(). */ const char *print_tainted(void) { static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")]; if (tainted_mask) { char *s; int i; s = buf + sprintf(buf, "Tainted: "); for (i = 0; i < ARRAY_SIZE(tnts); i++) { const struct tnt *t = &tnts[i]; *s++ = test_bit(t->bit, &tainted_mask) ? t->true : t->false; } *s = 0; } else snprintf(buf, sizeof(buf), "Not tainted"); return buf; } int test_taint(unsigned flag) { return test_bit(flag, &tainted_mask); } EXPORT_SYMBOL(test_taint); unsigned long get_taint(void) { return tainted_mask; } /** * add_taint: add a taint flag if not already set. * @flag: one of the TAINT_* constants. * @lockdep_ok: whether lock debugging is still OK. * * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for * some notewortht-but-not-corrupting cases, it can be set to true. */ void add_taint(unsigned flag, enum lockdep_ok lockdep_ok) { if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off()) pr_warn("Disabling lock debugging due to kernel taint\n"); set_bit(flag, &tainted_mask); } EXPORT_SYMBOL(add_taint); static void spin_msec(int msecs) { int i; for (i = 0; i < msecs; i++) { touch_nmi_watchdog(); mdelay(1); } } /* * It just happens that oops_enter() and oops_exit() are identically * implemented... */ static void do_oops_enter_exit(void) { unsigned long flags; static int spin_counter; if (!pause_on_oops) return; spin_lock_irqsave(&pause_on_oops_lock, flags); if (pause_on_oops_flag == 0) { /* This CPU may now print the oops message */ pause_on_oops_flag = 1; } else { /* We need to stall this CPU */ if (!spin_counter) { /* This CPU gets to do the counting */ spin_counter = pause_on_oops; do { spin_unlock(&pause_on_oops_lock); spin_msec(MSEC_PER_SEC); spin_lock(&pause_on_oops_lock); } while (--spin_counter); pause_on_oops_flag = 0; } else { /* This CPU waits for a different one */ while (spin_counter) { spin_unlock(&pause_on_oops_lock); spin_msec(1); spin_lock(&pause_on_oops_lock); } } } spin_unlock_irqrestore(&pause_on_oops_lock, flags); } /* * Return true if the calling CPU is allowed to print oops-related info. * This is a bit racy.. */ int oops_may_print(void) { return pause_on_oops_flag == 0; } /* * Called when the architecture enters its oops handler, before it prints * anything. If this is the first CPU to oops, and it's oopsing the first * time then let it proceed. * * This is all enabled by the pause_on_oops kernel boot option. We do all * this to ensure that oopses don't scroll off the screen. It has the * side-effect of preventing later-oopsing CPUs from mucking up the display, * too. * * It turns out that the CPU which is allowed to print ends up pausing for * the right duration, whereas all the other CPUs pause for twice as long: * once in oops_enter(), once in oops_exit(). */ void oops_enter(void) { tracing_off(); /* can't trust the integrity of the kernel anymore: */ debug_locks_off(); do_oops_enter_exit(); } /* * 64-bit random ID for oopses: */ static u64 oops_id; static int init_oops_id(void) { if (!oops_id) get_random_bytes(&oops_id, sizeof(oops_id)); else oops_id++; return 0; } late_initcall(init_oops_id); void print_oops_end_marker(void) { init_oops_id(); pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id); } /* * Called when the architecture exits its oops handler, after printing * everything. */ void oops_exit(void) { do_oops_enter_exit(); print_oops_end_marker(); kmsg_dump(KMSG_DUMP_OOPS); } #ifdef WANT_WARN_ON_SLOWPATH struct slowpath_args { const char *fmt; va_list args; }; static void warn_slowpath_common(const char *file, int line, void *caller, unsigned taint, struct slowpath_args *args) { disable_trace_on_warning(); pr_warn("------------[ cut here ]------------\n"); pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n", raw_smp_processor_id(), current->pid, file, line, caller); if (args) vprintk(args->fmt, args->args); if (panic_on_warn) { /* * This thread may hit another WARN() in the panic path. * Resetting this prevents additional WARN() from panicking the * system on this thread. Other threads are blocked by the * panic_mutex in panic(). */ panic_on_warn = 0; panic("panic_on_warn set ...\n"); } print_modules(); dump_stack(); print_oops_end_marker(); /* Just a warning, don't kill lockdep. */ add_taint(taint, LOCKDEP_STILL_OK); } void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) { struct slowpath_args args; args.fmt = fmt; va_start(args.args, fmt); warn_slowpath_common(file, line, __builtin_return_address(0), TAINT_WARN, &args); va_end(args.args); } EXPORT_SYMBOL(warn_slowpath_fmt); void warn_slowpath_fmt_taint(const char *file, int line, unsigned taint, const char *fmt, ...) { struct slowpath_args args; args.fmt = fmt; va_start(args.args, fmt); warn_slowpath_common(file, line, __builtin_return_address(0), taint, &args); va_end(args.args); } EXPORT_SYMBOL(warn_slowpath_fmt_taint); void warn_slowpath_null(const char *file, int line) { warn_slowpath_common(file, line, __builtin_return_address(0), TAINT_WARN, NULL); } EXPORT_SYMBOL(warn_slowpath_null); #endif #ifdef CONFIG_CC_STACKPROTECTOR /* * Called when gcc's -fstack-protector feature is used, and * gcc detects corruption of the on-stack canary value */ __visible void __stack_chk_fail(void) { panic("stack-protector: Kernel stack is corrupted in: %p\n", __builtin_return_address(0)); } EXPORT_SYMBOL(__stack_chk_fail); #endif core_param(panic, panic_timeout, int, 0644); core_param(pause_on_oops, pause_on_oops, int, 0644); core_param(panic_on_warn, panic_on_warn, int, 0644); static int __init setup_crash_kexec_post_notifiers(char *s) { crash_kexec_post_notifiers = true; return 0; } early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers); static int __init oops_setup(char *s) { if (!s) return -EINVAL; if (!strcmp(s, "panic")) panic_on_oops = 1; return 0; } early_param("oops", oops_setup);