/* * 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/kallsyms.h> #include <linux/notifier.h> #include <linux/module.h> #include <linux/random.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> #include <linux/dmi.h> int panic_on_oops; static unsigned long tainted_mask; static int pause_on_oops; static int pause_on_oops_flag; static DEFINE_SPINLOCK(pause_on_oops_lock); int panic_timeout; ATOMIC_NOTIFIER_HEAD(panic_notifier_list); EXPORT_SYMBOL(panic_notifier_list); static long no_blink(long time) { return 0; } /* Returns how long it waited in ms */ long (*panic_blink)(long time); EXPORT_SYMBOL(panic_blink); /** * panic - halt the system * @fmt: The text string to print * * Display a message, then perform cleanups. * * This function never returns. */ NORET_TYPE void panic(const char * fmt, ...) { static char buf[1024]; va_list args; long i; /* * 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... */ preempt_disable(); bust_spinlocks(1); va_start(args, fmt); vsnprintf(buf, sizeof(buf), fmt, args); va_end(args); printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); #ifdef CONFIG_DEBUG_BUGVERBOSE dump_stack(); #endif /* * If we have crashed and we have a crash kernel loaded let it handle * everything else. * Do we want to call this before we try to display a message? */ 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(); atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 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. */ printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout); for (i = 0; i < panic_timeout*1000; ) { touch_nmi_watchdog(); i += panic_blink(i); mdelay(1); i++; } /* * 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; printk(KERN_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 local_irq_enable(); for (i = 0; ; ) { touch_softlockup_watchdog(); i += panic_blink(i); mdelay(1); i++; } } 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_UNSAFE_SMP, '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', ' ' }, }; /** * 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. * * The string is overwritten by the next call to print_tainted(). */ const char *print_tainted(void) { static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1]; 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; } void add_taint(unsigned flag) { /* * Can't trust the integrity of the kernel anymore. * We don't call directly debug_locks_off() because the issue * is not necessarily serious enough to set oops_in_progress to 1 * Also we want to keep up lockdep for staging development and * post-warning case. */ if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off()) printk(KERN_WARNING "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); static void print_oops_end_marker(void) { init_oops_id(); printk(KERN_WARNING "---[ 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(); } #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, struct slowpath_args *args) { const char *board; printk(KERN_WARNING "------------[ cut here ]------------\n"); printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller); board = dmi_get_system_info(DMI_PRODUCT_NAME); if (board) printk(KERN_WARNING "Hardware name: %s\n", board); if (args) vprintk(args->fmt, args->args); print_modules(); dump_stack(); print_oops_end_marker(); add_taint(TAINT_WARN); } 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), &args); va_end(args.args); } EXPORT_SYMBOL(warn_slowpath_fmt); void warn_slowpath_null(const char *file, int line) { warn_slowpath_common(file, line, __builtin_return_address(0), 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 */ 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);