1 /* 2 * linux/kernel/panic.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 */ 6 7 /* 8 * This function is used through-out the kernel (including mm and fs) 9 * to indicate a major problem. 10 */ 11 #include <linux/module.h> 12 #include <linux/sched.h> 13 #include <linux/delay.h> 14 #include <linux/reboot.h> 15 #include <linux/notifier.h> 16 #include <linux/init.h> 17 #include <linux/sysrq.h> 18 #include <linux/interrupt.h> 19 #include <linux/nmi.h> 20 #include <linux/kexec.h> 21 #include <linux/debug_locks.h> 22 23 int panic_on_oops; 24 int tainted; 25 static int pause_on_oops; 26 static int pause_on_oops_flag; 27 static DEFINE_SPINLOCK(pause_on_oops_lock); 28 29 int panic_timeout; 30 31 ATOMIC_NOTIFIER_HEAD(panic_notifier_list); 32 33 EXPORT_SYMBOL(panic_notifier_list); 34 35 static int __init panic_setup(char *str) 36 { 37 panic_timeout = simple_strtoul(str, NULL, 0); 38 return 1; 39 } 40 __setup("panic=", panic_setup); 41 42 static long no_blink(long time) 43 { 44 return 0; 45 } 46 47 /* Returns how long it waited in ms */ 48 long (*panic_blink)(long time); 49 EXPORT_SYMBOL(panic_blink); 50 51 /** 52 * panic - halt the system 53 * @fmt: The text string to print 54 * 55 * Display a message, then perform cleanups. 56 * 57 * This function never returns. 58 */ 59 60 NORET_TYPE void panic(const char * fmt, ...) 61 { 62 long i; 63 static char buf[1024]; 64 va_list args; 65 #if defined(CONFIG_S390) 66 unsigned long caller = (unsigned long) __builtin_return_address(0); 67 #endif 68 69 /* 70 * It's possible to come here directly from a panic-assertion and not 71 * have preempt disabled. Some functions called from here want 72 * preempt to be disabled. No point enabling it later though... 73 */ 74 preempt_disable(); 75 76 bust_spinlocks(1); 77 va_start(args, fmt); 78 vsnprintf(buf, sizeof(buf), fmt, args); 79 va_end(args); 80 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); 81 bust_spinlocks(0); 82 83 /* 84 * If we have crashed and we have a crash kernel loaded let it handle 85 * everything else. 86 * Do we want to call this before we try to display a message? 87 */ 88 crash_kexec(NULL); 89 90 #ifdef CONFIG_SMP 91 /* 92 * Note smp_send_stop is the usual smp shutdown function, which 93 * unfortunately means it may not be hardened to work in a panic 94 * situation. 95 */ 96 smp_send_stop(); 97 #endif 98 99 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 100 101 if (!panic_blink) 102 panic_blink = no_blink; 103 104 if (panic_timeout > 0) { 105 /* 106 * Delay timeout seconds before rebooting the machine. 107 * We can't use the "normal" timers since we just panicked.. 108 */ 109 printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout); 110 for (i = 0; i < panic_timeout*1000; ) { 111 touch_nmi_watchdog(); 112 i += panic_blink(i); 113 mdelay(1); 114 i++; 115 } 116 /* This will not be a clean reboot, with everything 117 * shutting down. But if there is a chance of 118 * rebooting the system it will be rebooted. 119 */ 120 emergency_restart(); 121 } 122 #ifdef __sparc__ 123 { 124 extern int stop_a_enabled; 125 /* Make sure the user can actually press Stop-A (L1-A) */ 126 stop_a_enabled = 1; 127 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); 128 } 129 #endif 130 #if defined(CONFIG_S390) 131 disabled_wait(caller); 132 #endif 133 local_irq_enable(); 134 for (i = 0;;) { 135 touch_softlockup_watchdog(); 136 i += panic_blink(i); 137 mdelay(1); 138 i++; 139 } 140 } 141 142 EXPORT_SYMBOL(panic); 143 144 /** 145 * print_tainted - return a string to represent the kernel taint state. 146 * 147 * 'P' - Proprietary module has been loaded. 148 * 'F' - Module has been forcibly loaded. 149 * 'S' - SMP with CPUs not designed for SMP. 150 * 'R' - User forced a module unload. 151 * 'M' - Machine had a machine check experience. 152 * 'B' - System has hit bad_page. 153 * 154 * The string is overwritten by the next call to print_taint(). 155 */ 156 157 const char *print_tainted(void) 158 { 159 static char buf[20]; 160 if (tainted) { 161 snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c", 162 tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G', 163 tainted & TAINT_FORCED_MODULE ? 'F' : ' ', 164 tainted & TAINT_UNSAFE_SMP ? 'S' : ' ', 165 tainted & TAINT_FORCED_RMMOD ? 'R' : ' ', 166 tainted & TAINT_MACHINE_CHECK ? 'M' : ' ', 167 tainted & TAINT_BAD_PAGE ? 'B' : ' '); 168 } 169 else 170 snprintf(buf, sizeof(buf), "Not tainted"); 171 return(buf); 172 } 173 174 void add_taint(unsigned flag) 175 { 176 debug_locks = 0; /* can't trust the integrity of the kernel anymore */ 177 tainted |= flag; 178 } 179 EXPORT_SYMBOL(add_taint); 180 181 static int __init pause_on_oops_setup(char *str) 182 { 183 pause_on_oops = simple_strtoul(str, NULL, 0); 184 return 1; 185 } 186 __setup("pause_on_oops=", pause_on_oops_setup); 187 188 static void spin_msec(int msecs) 189 { 190 int i; 191 192 for (i = 0; i < msecs; i++) { 193 touch_nmi_watchdog(); 194 mdelay(1); 195 } 196 } 197 198 /* 199 * It just happens that oops_enter() and oops_exit() are identically 200 * implemented... 201 */ 202 static void do_oops_enter_exit(void) 203 { 204 unsigned long flags; 205 static int spin_counter; 206 207 if (!pause_on_oops) 208 return; 209 210 spin_lock_irqsave(&pause_on_oops_lock, flags); 211 if (pause_on_oops_flag == 0) { 212 /* This CPU may now print the oops message */ 213 pause_on_oops_flag = 1; 214 } else { 215 /* We need to stall this CPU */ 216 if (!spin_counter) { 217 /* This CPU gets to do the counting */ 218 spin_counter = pause_on_oops; 219 do { 220 spin_unlock(&pause_on_oops_lock); 221 spin_msec(MSEC_PER_SEC); 222 spin_lock(&pause_on_oops_lock); 223 } while (--spin_counter); 224 pause_on_oops_flag = 0; 225 } else { 226 /* This CPU waits for a different one */ 227 while (spin_counter) { 228 spin_unlock(&pause_on_oops_lock); 229 spin_msec(1); 230 spin_lock(&pause_on_oops_lock); 231 } 232 } 233 } 234 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 235 } 236 237 /* 238 * Return true if the calling CPU is allowed to print oops-related info. This 239 * is a bit racy.. 240 */ 241 int oops_may_print(void) 242 { 243 return pause_on_oops_flag == 0; 244 } 245 246 /* 247 * Called when the architecture enters its oops handler, before it prints 248 * anything. If this is the first CPU to oops, and it's oopsing the first time 249 * then let it proceed. 250 * 251 * This is all enabled by the pause_on_oops kernel boot option. We do all this 252 * to ensure that oopses don't scroll off the screen. It has the side-effect 253 * of preventing later-oopsing CPUs from mucking up the display, too. 254 * 255 * It turns out that the CPU which is allowed to print ends up pausing for the 256 * right duration, whereas all the other CPUs pause for twice as long: once in 257 * oops_enter(), once in oops_exit(). 258 */ 259 void oops_enter(void) 260 { 261 debug_locks_off(); /* can't trust the integrity of the kernel anymore */ 262 do_oops_enter_exit(); 263 } 264 265 /* 266 * Called when the architecture exits its oops handler, after printing 267 * everything. 268 */ 269 void oops_exit(void) 270 { 271 do_oops_enter_exit(); 272 } 273