/* * 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/module.h> #include <linux/sched.h> #include <linux/delay.h> #include <linux/reboot.h> #include <linux/notifier.h> #include <linux/init.h> #include <linux/sysrq.h> #include <linux/interrupt.h> #include <linux/nmi.h> #include <linux/kexec.h> #include <linux/debug_locks.h> int panic_on_oops; int tainted; 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 int __init panic_setup(char *str) { panic_timeout = simple_strtoul(str, NULL, 0); return 1; } __setup("panic=", panic_setup); 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, ...) { long i; static char buf[1024]; va_list args; #if defined(CONFIG_S390) unsigned long caller = (unsigned long) __builtin_return_address(0); #endif /* * 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); bust_spinlocks(0); /* * 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); #ifdef CONFIG_SMP /* * 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(); #endif atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 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) disabled_wait(caller); #endif local_irq_enable(); for (i = 0;;) { touch_softlockup_watchdog(); i += panic_blink(i); mdelay(1); i++; } } EXPORT_SYMBOL(panic); /** * 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' - Machine had a machine check experience. * 'B' - System has hit bad_page. * 'U' - Userspace-defined naughtiness. * * The string is overwritten by the next call to print_taint(). */ const char *print_tainted(void) { static char buf[20]; if (tainted) { snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c%c", tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G', tainted & TAINT_FORCED_MODULE ? 'F' : ' ', tainted & TAINT_UNSAFE_SMP ? 'S' : ' ', tainted & TAINT_FORCED_RMMOD ? 'R' : ' ', tainted & TAINT_MACHINE_CHECK ? 'M' : ' ', tainted & TAINT_BAD_PAGE ? 'B' : ' ', tainted & TAINT_USER ? 'U' : ' '); } else snprintf(buf, sizeof(buf), "Not tainted"); return(buf); } void add_taint(unsigned flag) { debug_locks = 0; /* can't trust the integrity of the kernel anymore */ tainted |= flag; } EXPORT_SYMBOL(add_taint); static int __init pause_on_oops_setup(char *str) { pause_on_oops = simple_strtoul(str, NULL, 0); return 1; } __setup("pause_on_oops=", pause_on_oops_setup); 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) { debug_locks_off(); /* can't trust the integrity of the kernel anymore */ do_oops_enter_exit(); } /* * Called when the architecture exits its oops handler, after printing * everything. */ void oops_exit(void) { do_oops_enter_exit(); } #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"); } EXPORT_SYMBOL(__stack_chk_fail); #endif