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%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 tainted & TAINT_DIE ? 'D' : ' '); 171 } 172 else 173 snprintf(buf, sizeof(buf), "Not tainted"); 174 return(buf); 175 } 176 177 void add_taint(unsigned flag) 178 { 179 debug_locks = 0; /* can't trust the integrity of the kernel anymore */ 180 tainted |= flag; 181 } 182 EXPORT_SYMBOL(add_taint); 183 184 static int __init pause_on_oops_setup(char *str) 185 { 186 pause_on_oops = simple_strtoul(str, NULL, 0); 187 return 1; 188 } 189 __setup("pause_on_oops=", pause_on_oops_setup); 190 191 static void spin_msec(int msecs) 192 { 193 int i; 194 195 for (i = 0; i < msecs; i++) { 196 touch_nmi_watchdog(); 197 mdelay(1); 198 } 199 } 200 201 /* 202 * It just happens that oops_enter() and oops_exit() are identically 203 * implemented... 204 */ 205 static void do_oops_enter_exit(void) 206 { 207 unsigned long flags; 208 static int spin_counter; 209 210 if (!pause_on_oops) 211 return; 212 213 spin_lock_irqsave(&pause_on_oops_lock, flags); 214 if (pause_on_oops_flag == 0) { 215 /* This CPU may now print the oops message */ 216 pause_on_oops_flag = 1; 217 } else { 218 /* We need to stall this CPU */ 219 if (!spin_counter) { 220 /* This CPU gets to do the counting */ 221 spin_counter = pause_on_oops; 222 do { 223 spin_unlock(&pause_on_oops_lock); 224 spin_msec(MSEC_PER_SEC); 225 spin_lock(&pause_on_oops_lock); 226 } while (--spin_counter); 227 pause_on_oops_flag = 0; 228 } else { 229 /* This CPU waits for a different one */ 230 while (spin_counter) { 231 spin_unlock(&pause_on_oops_lock); 232 spin_msec(1); 233 spin_lock(&pause_on_oops_lock); 234 } 235 } 236 } 237 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 238 } 239 240 /* 241 * Return true if the calling CPU is allowed to print oops-related info. This 242 * is a bit racy.. 243 */ 244 int oops_may_print(void) 245 { 246 return pause_on_oops_flag == 0; 247 } 248 249 /* 250 * Called when the architecture enters its oops handler, before it prints 251 * anything. If this is the first CPU to oops, and it's oopsing the first time 252 * then let it proceed. 253 * 254 * This is all enabled by the pause_on_oops kernel boot option. We do all this 255 * to ensure that oopses don't scroll off the screen. It has the side-effect 256 * of preventing later-oopsing CPUs from mucking up the display, too. 257 * 258 * It turns out that the CPU which is allowed to print ends up pausing for the 259 * right duration, whereas all the other CPUs pause for twice as long: once in 260 * oops_enter(), once in oops_exit(). 261 */ 262 void oops_enter(void) 263 { 264 debug_locks_off(); /* can't trust the integrity of the kernel anymore */ 265 do_oops_enter_exit(); 266 } 267 268 /* 269 * Called when the architecture exits its oops handler, after printing 270 * everything. 271 */ 272 void oops_exit(void) 273 { 274 do_oops_enter_exit(); 275 } 276 277 #ifdef CONFIG_CC_STACKPROTECTOR 278 /* 279 * Called when gcc's -fstack-protector feature is used, and 280 * gcc detects corruption of the on-stack canary value 281 */ 282 void __stack_chk_fail(void) 283 { 284 panic("stack-protector: Kernel stack is corrupted"); 285 } 286 EXPORT_SYMBOL(__stack_chk_fail); 287 #endif 288