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 * 'U' - Userspace-defined naughtiness. 154 * 155 * The string is overwritten by the next call to print_taint(). 156 */ 157 158 const char *print_tainted(void) 159 { 160 static char buf[20]; 161 if (tainted) { 162 snprintf(buf, sizeof(buf), "Tainted: %c%c%c%c%c%c%c", 163 tainted & TAINT_PROPRIETARY_MODULE ? 'P' : 'G', 164 tainted & TAINT_FORCED_MODULE ? 'F' : ' ', 165 tainted & TAINT_UNSAFE_SMP ? 'S' : ' ', 166 tainted & TAINT_FORCED_RMMOD ? 'R' : ' ', 167 tainted & TAINT_MACHINE_CHECK ? 'M' : ' ', 168 tainted & TAINT_BAD_PAGE ? 'B' : ' ', 169 tainted & TAINT_USER ? 'U' : ' '); 170 } 171 else 172 snprintf(buf, sizeof(buf), "Not tainted"); 173 return(buf); 174 } 175 176 void add_taint(unsigned flag) 177 { 178 debug_locks = 0; /* can't trust the integrity of the kernel anymore */ 179 tainted |= flag; 180 } 181 EXPORT_SYMBOL(add_taint); 182 183 static int __init pause_on_oops_setup(char *str) 184 { 185 pause_on_oops = simple_strtoul(str, NULL, 0); 186 return 1; 187 } 188 __setup("pause_on_oops=", pause_on_oops_setup); 189 190 static void spin_msec(int msecs) 191 { 192 int i; 193 194 for (i = 0; i < msecs; i++) { 195 touch_nmi_watchdog(); 196 mdelay(1); 197 } 198 } 199 200 /* 201 * It just happens that oops_enter() and oops_exit() are identically 202 * implemented... 203 */ 204 static void do_oops_enter_exit(void) 205 { 206 unsigned long flags; 207 static int spin_counter; 208 209 if (!pause_on_oops) 210 return; 211 212 spin_lock_irqsave(&pause_on_oops_lock, flags); 213 if (pause_on_oops_flag == 0) { 214 /* This CPU may now print the oops message */ 215 pause_on_oops_flag = 1; 216 } else { 217 /* We need to stall this CPU */ 218 if (!spin_counter) { 219 /* This CPU gets to do the counting */ 220 spin_counter = pause_on_oops; 221 do { 222 spin_unlock(&pause_on_oops_lock); 223 spin_msec(MSEC_PER_SEC); 224 spin_lock(&pause_on_oops_lock); 225 } while (--spin_counter); 226 pause_on_oops_flag = 0; 227 } else { 228 /* This CPU waits for a different one */ 229 while (spin_counter) { 230 spin_unlock(&pause_on_oops_lock); 231 spin_msec(1); 232 spin_lock(&pause_on_oops_lock); 233 } 234 } 235 } 236 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 237 } 238 239 /* 240 * Return true if the calling CPU is allowed to print oops-related info. This 241 * is a bit racy.. 242 */ 243 int oops_may_print(void) 244 { 245 return pause_on_oops_flag == 0; 246 } 247 248 /* 249 * Called when the architecture enters its oops handler, before it prints 250 * anything. If this is the first CPU to oops, and it's oopsing the first time 251 * then let it proceed. 252 * 253 * This is all enabled by the pause_on_oops kernel boot option. We do all this 254 * to ensure that oopses don't scroll off the screen. It has the side-effect 255 * of preventing later-oopsing CPUs from mucking up the display, too. 256 * 257 * It turns out that the CPU which is allowed to print ends up pausing for the 258 * right duration, whereas all the other CPUs pause for twice as long: once in 259 * oops_enter(), once in oops_exit(). 260 */ 261 void oops_enter(void) 262 { 263 debug_locks_off(); /* can't trust the integrity of the kernel anymore */ 264 do_oops_enter_exit(); 265 } 266 267 /* 268 * Called when the architecture exits its oops handler, after printing 269 * everything. 270 */ 271 void oops_exit(void) 272 { 273 do_oops_enter_exit(); 274 } 275 276 #ifdef CONFIG_CC_STACKPROTECTOR 277 /* 278 * Called when gcc's -fstack-protector feature is used, and 279 * gcc detects corruption of the on-stack canary value 280 */ 281 void __stack_chk_fail(void) 282 { 283 panic("stack-protector: Kernel stack is corrupted"); 284 } 285 EXPORT_SYMBOL(__stack_chk_fail); 286 #endif 287