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 #include <linux/random.h> 23 #include <linux/kallsyms.h> 24 25 int panic_on_oops; 26 static unsigned long tainted_mask; 27 static int pause_on_oops; 28 static int pause_on_oops_flag; 29 static DEFINE_SPINLOCK(pause_on_oops_lock); 30 31 int panic_timeout; 32 33 ATOMIC_NOTIFIER_HEAD(panic_notifier_list); 34 35 EXPORT_SYMBOL(panic_notifier_list); 36 37 static int __init panic_setup(char *str) 38 { 39 panic_timeout = simple_strtoul(str, NULL, 0); 40 return 1; 41 } 42 __setup("panic=", panic_setup); 43 44 static long no_blink(long time) 45 { 46 return 0; 47 } 48 49 /* Returns how long it waited in ms */ 50 long (*panic_blink)(long time); 51 EXPORT_SYMBOL(panic_blink); 52 53 /** 54 * panic - halt the system 55 * @fmt: The text string to print 56 * 57 * Display a message, then perform cleanups. 58 * 59 * This function never returns. 60 */ 61 62 NORET_TYPE void panic(const char * fmt, ...) 63 { 64 long i; 65 static char buf[1024]; 66 va_list args; 67 #if defined(CONFIG_S390) 68 unsigned long caller = (unsigned long) __builtin_return_address(0); 69 #endif 70 71 /* 72 * It's possible to come here directly from a panic-assertion and not 73 * have preempt disabled. Some functions called from here want 74 * preempt to be disabled. No point enabling it later though... 75 */ 76 preempt_disable(); 77 78 bust_spinlocks(1); 79 va_start(args, fmt); 80 vsnprintf(buf, sizeof(buf), fmt, args); 81 va_end(args); 82 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); 83 bust_spinlocks(0); 84 85 /* 86 * If we have crashed and we have a crash kernel loaded let it handle 87 * everything else. 88 * Do we want to call this before we try to display a message? 89 */ 90 crash_kexec(NULL); 91 92 #ifdef CONFIG_SMP 93 /* 94 * Note smp_send_stop is the usual smp shutdown function, which 95 * unfortunately means it may not be hardened to work in a panic 96 * situation. 97 */ 98 smp_send_stop(); 99 #endif 100 101 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 102 103 if (!panic_blink) 104 panic_blink = no_blink; 105 106 if (panic_timeout > 0) { 107 /* 108 * Delay timeout seconds before rebooting the machine. 109 * We can't use the "normal" timers since we just panicked.. 110 */ 111 printk(KERN_EMERG "Rebooting in %d seconds..",panic_timeout); 112 for (i = 0; i < panic_timeout*1000; ) { 113 touch_nmi_watchdog(); 114 i += panic_blink(i); 115 mdelay(1); 116 i++; 117 } 118 /* This will not be a clean reboot, with everything 119 * shutting down. But if there is a chance of 120 * rebooting the system it will be rebooted. 121 */ 122 emergency_restart(); 123 } 124 #ifdef __sparc__ 125 { 126 extern int stop_a_enabled; 127 /* Make sure the user can actually press Stop-A (L1-A) */ 128 stop_a_enabled = 1; 129 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); 130 } 131 #endif 132 #if defined(CONFIG_S390) 133 disabled_wait(caller); 134 #endif 135 local_irq_enable(); 136 for (i = 0;;) { 137 touch_softlockup_watchdog(); 138 i += panic_blink(i); 139 mdelay(1); 140 i++; 141 } 142 } 143 144 EXPORT_SYMBOL(panic); 145 146 147 struct tnt { 148 u8 bit; 149 char true; 150 char false; 151 }; 152 153 static const struct tnt tnts[] = { 154 { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, 155 { TAINT_FORCED_MODULE, 'F', ' ' }, 156 { TAINT_UNSAFE_SMP, 'S', ' ' }, 157 { TAINT_FORCED_RMMOD, 'R', ' ' }, 158 { TAINT_MACHINE_CHECK, 'M', ' ' }, 159 { TAINT_BAD_PAGE, 'B', ' ' }, 160 { TAINT_USER, 'U', ' ' }, 161 { TAINT_DIE, 'D', ' ' }, 162 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, 163 { TAINT_WARN, 'W', ' ' }, 164 { TAINT_CRAP, 'C', ' ' }, 165 }; 166 167 /** 168 * print_tainted - return a string to represent the kernel taint state. 169 * 170 * 'P' - Proprietary module has been loaded. 171 * 'F' - Module has been forcibly loaded. 172 * 'S' - SMP with CPUs not designed for SMP. 173 * 'R' - User forced a module unload. 174 * 'M' - System experienced a machine check exception. 175 * 'B' - System has hit bad_page. 176 * 'U' - Userspace-defined naughtiness. 177 * 'A' - ACPI table overridden. 178 * 'W' - Taint on warning. 179 * 'C' - modules from drivers/staging are loaded. 180 * 181 * The string is overwritten by the next call to print_taint(). 182 */ 183 const char *print_tainted(void) 184 { 185 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1]; 186 187 if (tainted_mask) { 188 char *s; 189 int i; 190 191 s = buf + sprintf(buf, "Tainted: "); 192 for (i = 0; i < ARRAY_SIZE(tnts); i++) { 193 const struct tnt *t = &tnts[i]; 194 *s++ = test_bit(t->bit, &tainted_mask) ? 195 t->true : t->false; 196 } 197 *s = 0; 198 } else 199 snprintf(buf, sizeof(buf), "Not tainted"); 200 return(buf); 201 } 202 203 int test_taint(unsigned flag) 204 { 205 return test_bit(flag, &tainted_mask); 206 } 207 EXPORT_SYMBOL(test_taint); 208 209 unsigned long get_taint(void) 210 { 211 return tainted_mask; 212 } 213 214 void add_taint(unsigned flag) 215 { 216 debug_locks = 0; /* can't trust the integrity of the kernel anymore */ 217 set_bit(flag, &tainted_mask); 218 } 219 EXPORT_SYMBOL(add_taint); 220 221 static int __init pause_on_oops_setup(char *str) 222 { 223 pause_on_oops = simple_strtoul(str, NULL, 0); 224 return 1; 225 } 226 __setup("pause_on_oops=", pause_on_oops_setup); 227 228 static void spin_msec(int msecs) 229 { 230 int i; 231 232 for (i = 0; i < msecs; i++) { 233 touch_nmi_watchdog(); 234 mdelay(1); 235 } 236 } 237 238 /* 239 * It just happens that oops_enter() and oops_exit() are identically 240 * implemented... 241 */ 242 static void do_oops_enter_exit(void) 243 { 244 unsigned long flags; 245 static int spin_counter; 246 247 if (!pause_on_oops) 248 return; 249 250 spin_lock_irqsave(&pause_on_oops_lock, flags); 251 if (pause_on_oops_flag == 0) { 252 /* This CPU may now print the oops message */ 253 pause_on_oops_flag = 1; 254 } else { 255 /* We need to stall this CPU */ 256 if (!spin_counter) { 257 /* This CPU gets to do the counting */ 258 spin_counter = pause_on_oops; 259 do { 260 spin_unlock(&pause_on_oops_lock); 261 spin_msec(MSEC_PER_SEC); 262 spin_lock(&pause_on_oops_lock); 263 } while (--spin_counter); 264 pause_on_oops_flag = 0; 265 } else { 266 /* This CPU waits for a different one */ 267 while (spin_counter) { 268 spin_unlock(&pause_on_oops_lock); 269 spin_msec(1); 270 spin_lock(&pause_on_oops_lock); 271 } 272 } 273 } 274 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 275 } 276 277 /* 278 * Return true if the calling CPU is allowed to print oops-related info. This 279 * is a bit racy.. 280 */ 281 int oops_may_print(void) 282 { 283 return pause_on_oops_flag == 0; 284 } 285 286 /* 287 * Called when the architecture enters its oops handler, before it prints 288 * anything. If this is the first CPU to oops, and it's oopsing the first time 289 * then let it proceed. 290 * 291 * This is all enabled by the pause_on_oops kernel boot option. We do all this 292 * to ensure that oopses don't scroll off the screen. It has the side-effect 293 * of preventing later-oopsing CPUs from mucking up the display, too. 294 * 295 * It turns out that the CPU which is allowed to print ends up pausing for the 296 * right duration, whereas all the other CPUs pause for twice as long: once in 297 * oops_enter(), once in oops_exit(). 298 */ 299 void oops_enter(void) 300 { 301 debug_locks_off(); /* can't trust the integrity of the kernel anymore */ 302 do_oops_enter_exit(); 303 } 304 305 /* 306 * 64-bit random ID for oopses: 307 */ 308 static u64 oops_id; 309 310 static int init_oops_id(void) 311 { 312 if (!oops_id) 313 get_random_bytes(&oops_id, sizeof(oops_id)); 314 315 return 0; 316 } 317 late_initcall(init_oops_id); 318 319 static void print_oops_end_marker(void) 320 { 321 init_oops_id(); 322 printk(KERN_WARNING "---[ end trace %016llx ]---\n", 323 (unsigned long long)oops_id); 324 } 325 326 /* 327 * Called when the architecture exits its oops handler, after printing 328 * everything. 329 */ 330 void oops_exit(void) 331 { 332 do_oops_enter_exit(); 333 print_oops_end_marker(); 334 } 335 336 #ifdef WANT_WARN_ON_SLOWPATH 337 void warn_on_slowpath(const char *file, int line) 338 { 339 char function[KSYM_SYMBOL_LEN]; 340 unsigned long caller = (unsigned long) __builtin_return_address(0); 341 sprint_symbol(function, caller); 342 343 printk(KERN_WARNING "------------[ cut here ]------------\n"); 344 printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file, 345 line, function); 346 print_modules(); 347 dump_stack(); 348 print_oops_end_marker(); 349 add_taint(TAINT_WARN); 350 } 351 EXPORT_SYMBOL(warn_on_slowpath); 352 353 354 void warn_slowpath(const char *file, int line, const char *fmt, ...) 355 { 356 va_list args; 357 char function[KSYM_SYMBOL_LEN]; 358 unsigned long caller = (unsigned long)__builtin_return_address(0); 359 sprint_symbol(function, caller); 360 361 printk(KERN_WARNING "------------[ cut here ]------------\n"); 362 printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file, 363 line, function); 364 va_start(args, fmt); 365 vprintk(fmt, args); 366 va_end(args); 367 368 print_modules(); 369 dump_stack(); 370 print_oops_end_marker(); 371 add_taint(TAINT_WARN); 372 } 373 EXPORT_SYMBOL(warn_slowpath); 374 #endif 375 376 #ifdef CONFIG_CC_STACKPROTECTOR 377 /* 378 * Called when gcc's -fstack-protector feature is used, and 379 * gcc detects corruption of the on-stack canary value 380 */ 381 void __stack_chk_fail(void) 382 { 383 panic("stack-protector: Kernel stack is corrupted"); 384 } 385 EXPORT_SYMBOL(__stack_chk_fail); 386 #endif 387