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/debug_locks.h> 12 #include <linux/interrupt.h> 13 #include <linux/kmsg_dump.h> 14 #include <linux/kallsyms.h> 15 #include <linux/notifier.h> 16 #include <linux/module.h> 17 #include <linux/random.h> 18 #include <linux/reboot.h> 19 #include <linux/delay.h> 20 #include <linux/kexec.h> 21 #include <linux/sched.h> 22 #include <linux/sysrq.h> 23 #include <linux/init.h> 24 #include <linux/nmi.h> 25 #include <linux/dmi.h> 26 27 #define PANIC_TIMER_STEP 100 28 #define PANIC_BLINK_SPD 18 29 30 int panic_on_oops; 31 static unsigned long tainted_mask; 32 static int pause_on_oops; 33 static int pause_on_oops_flag; 34 static DEFINE_SPINLOCK(pause_on_oops_lock); 35 36 int panic_timeout; 37 EXPORT_SYMBOL_GPL(panic_timeout); 38 39 ATOMIC_NOTIFIER_HEAD(panic_notifier_list); 40 41 EXPORT_SYMBOL(panic_notifier_list); 42 43 static long no_blink(int state) 44 { 45 return 0; 46 } 47 48 /* Returns how long it waited in ms */ 49 long (*panic_blink)(int state); 50 EXPORT_SYMBOL(panic_blink); 51 52 /** 53 * panic - halt the system 54 * @fmt: The text string to print 55 * 56 * Display a message, then perform cleanups. 57 * 58 * This function never returns. 59 */ 60 NORET_TYPE void panic(const char * fmt, ...) 61 { 62 static char buf[1024]; 63 va_list args; 64 long i, i_next = 0; 65 int state = 0; 66 67 /* 68 * It's possible to come here directly from a panic-assertion and 69 * not have preempt disabled. Some functions called from here want 70 * preempt to be disabled. No point enabling it later though... 71 */ 72 preempt_disable(); 73 74 console_verbose(); 75 bust_spinlocks(1); 76 va_start(args, fmt); 77 vsnprintf(buf, sizeof(buf), fmt, args); 78 va_end(args); 79 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); 80 #ifdef CONFIG_DEBUG_BUGVERBOSE 81 dump_stack(); 82 #endif 83 84 /* 85 * If we have crashed and we have a crash kernel loaded let it handle 86 * everything else. 87 * Do we want to call this before we try to display a message? 88 */ 89 crash_kexec(NULL); 90 91 kmsg_dump(KMSG_DUMP_PANIC); 92 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(); 99 100 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 101 102 bust_spinlocks(0); 103 104 if (!panic_blink) 105 panic_blink = no_blink; 106 107 if (panic_timeout > 0) { 108 /* 109 * Delay timeout seconds before rebooting the machine. 110 * We can't use the "normal" timers since we just panicked. 111 */ 112 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout); 113 114 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { 115 touch_nmi_watchdog(); 116 if (i >= i_next) { 117 i += panic_blink(state ^= 1); 118 i_next = i + 3600 / PANIC_BLINK_SPD; 119 } 120 mdelay(PANIC_TIMER_STEP); 121 } 122 } 123 if (panic_timeout != 0) { 124 /* 125 * This will not be a clean reboot, with everything 126 * shutting down. But if there is a chance of 127 * rebooting the system it will be rebooted. 128 */ 129 emergency_restart(); 130 } 131 #ifdef __sparc__ 132 { 133 extern int stop_a_enabled; 134 /* Make sure the user can actually press Stop-A (L1-A) */ 135 stop_a_enabled = 1; 136 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); 137 } 138 #endif 139 #if defined(CONFIG_S390) 140 { 141 unsigned long caller; 142 143 caller = (unsigned long)__builtin_return_address(0); 144 disabled_wait(caller); 145 } 146 #endif 147 local_irq_enable(); 148 for (i = 0; ; i += PANIC_TIMER_STEP) { 149 touch_softlockup_watchdog(); 150 if (i >= i_next) { 151 i += panic_blink(state ^= 1); 152 i_next = i + 3600 / PANIC_BLINK_SPD; 153 } 154 mdelay(PANIC_TIMER_STEP); 155 } 156 } 157 158 EXPORT_SYMBOL(panic); 159 160 161 struct tnt { 162 u8 bit; 163 char true; 164 char false; 165 }; 166 167 static const struct tnt tnts[] = { 168 { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, 169 { TAINT_FORCED_MODULE, 'F', ' ' }, 170 { TAINT_UNSAFE_SMP, 'S', ' ' }, 171 { TAINT_FORCED_RMMOD, 'R', ' ' }, 172 { TAINT_MACHINE_CHECK, 'M', ' ' }, 173 { TAINT_BAD_PAGE, 'B', ' ' }, 174 { TAINT_USER, 'U', ' ' }, 175 { TAINT_DIE, 'D', ' ' }, 176 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, 177 { TAINT_WARN, 'W', ' ' }, 178 { TAINT_CRAP, 'C', ' ' }, 179 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' }, 180 }; 181 182 /** 183 * print_tainted - return a string to represent the kernel taint state. 184 * 185 * 'P' - Proprietary module has been loaded. 186 * 'F' - Module has been forcibly loaded. 187 * 'S' - SMP with CPUs not designed for SMP. 188 * 'R' - User forced a module unload. 189 * 'M' - System experienced a machine check exception. 190 * 'B' - System has hit bad_page. 191 * 'U' - Userspace-defined naughtiness. 192 * 'D' - Kernel has oopsed before 193 * 'A' - ACPI table overridden. 194 * 'W' - Taint on warning. 195 * 'C' - modules from drivers/staging are loaded. 196 * 'I' - Working around severe firmware bug. 197 * 198 * The string is overwritten by the next call to print_tainted(). 199 */ 200 const char *print_tainted(void) 201 { 202 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1]; 203 204 if (tainted_mask) { 205 char *s; 206 int i; 207 208 s = buf + sprintf(buf, "Tainted: "); 209 for (i = 0; i < ARRAY_SIZE(tnts); i++) { 210 const struct tnt *t = &tnts[i]; 211 *s++ = test_bit(t->bit, &tainted_mask) ? 212 t->true : t->false; 213 } 214 *s = 0; 215 } else 216 snprintf(buf, sizeof(buf), "Not tainted"); 217 218 return buf; 219 } 220 221 int test_taint(unsigned flag) 222 { 223 return test_bit(flag, &tainted_mask); 224 } 225 EXPORT_SYMBOL(test_taint); 226 227 unsigned long get_taint(void) 228 { 229 return tainted_mask; 230 } 231 232 void add_taint(unsigned flag) 233 { 234 /* 235 * Can't trust the integrity of the kernel anymore. 236 * We don't call directly debug_locks_off() because the issue 237 * is not necessarily serious enough to set oops_in_progress to 1 238 * Also we want to keep up lockdep for staging development and 239 * post-warning case. 240 */ 241 if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off()) 242 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n"); 243 244 set_bit(flag, &tainted_mask); 245 } 246 EXPORT_SYMBOL(add_taint); 247 248 static void spin_msec(int msecs) 249 { 250 int i; 251 252 for (i = 0; i < msecs; i++) { 253 touch_nmi_watchdog(); 254 mdelay(1); 255 } 256 } 257 258 /* 259 * It just happens that oops_enter() and oops_exit() are identically 260 * implemented... 261 */ 262 static void do_oops_enter_exit(void) 263 { 264 unsigned long flags; 265 static int spin_counter; 266 267 if (!pause_on_oops) 268 return; 269 270 spin_lock_irqsave(&pause_on_oops_lock, flags); 271 if (pause_on_oops_flag == 0) { 272 /* This CPU may now print the oops message */ 273 pause_on_oops_flag = 1; 274 } else { 275 /* We need to stall this CPU */ 276 if (!spin_counter) { 277 /* This CPU gets to do the counting */ 278 spin_counter = pause_on_oops; 279 do { 280 spin_unlock(&pause_on_oops_lock); 281 spin_msec(MSEC_PER_SEC); 282 spin_lock(&pause_on_oops_lock); 283 } while (--spin_counter); 284 pause_on_oops_flag = 0; 285 } else { 286 /* This CPU waits for a different one */ 287 while (spin_counter) { 288 spin_unlock(&pause_on_oops_lock); 289 spin_msec(1); 290 spin_lock(&pause_on_oops_lock); 291 } 292 } 293 } 294 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 295 } 296 297 /* 298 * Return true if the calling CPU is allowed to print oops-related info. 299 * This is a bit racy.. 300 */ 301 int oops_may_print(void) 302 { 303 return pause_on_oops_flag == 0; 304 } 305 306 /* 307 * Called when the architecture enters its oops handler, before it prints 308 * anything. If this is the first CPU to oops, and it's oopsing the first 309 * time then let it proceed. 310 * 311 * This is all enabled by the pause_on_oops kernel boot option. We do all 312 * this to ensure that oopses don't scroll off the screen. It has the 313 * side-effect of preventing later-oopsing CPUs from mucking up the display, 314 * too. 315 * 316 * It turns out that the CPU which is allowed to print ends up pausing for 317 * the right duration, whereas all the other CPUs pause for twice as long: 318 * once in oops_enter(), once in oops_exit(). 319 */ 320 void oops_enter(void) 321 { 322 tracing_off(); 323 /* can't trust the integrity of the kernel anymore: */ 324 debug_locks_off(); 325 do_oops_enter_exit(); 326 } 327 328 /* 329 * 64-bit random ID for oopses: 330 */ 331 static u64 oops_id; 332 333 static int init_oops_id(void) 334 { 335 if (!oops_id) 336 get_random_bytes(&oops_id, sizeof(oops_id)); 337 else 338 oops_id++; 339 340 return 0; 341 } 342 late_initcall(init_oops_id); 343 344 void print_oops_end_marker(void) 345 { 346 init_oops_id(); 347 printk(KERN_WARNING "---[ end trace %016llx ]---\n", 348 (unsigned long long)oops_id); 349 } 350 351 /* 352 * Called when the architecture exits its oops handler, after printing 353 * everything. 354 */ 355 void oops_exit(void) 356 { 357 do_oops_enter_exit(); 358 print_oops_end_marker(); 359 kmsg_dump(KMSG_DUMP_OOPS); 360 } 361 362 #ifdef WANT_WARN_ON_SLOWPATH 363 struct slowpath_args { 364 const char *fmt; 365 va_list args; 366 }; 367 368 static void warn_slowpath_common(const char *file, int line, void *caller, 369 unsigned taint, struct slowpath_args *args) 370 { 371 const char *board; 372 373 printk(KERN_WARNING "------------[ cut here ]------------\n"); 374 printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller); 375 board = dmi_get_system_info(DMI_PRODUCT_NAME); 376 if (board) 377 printk(KERN_WARNING "Hardware name: %s\n", board); 378 379 if (args) 380 vprintk(args->fmt, args->args); 381 382 print_modules(); 383 dump_stack(); 384 print_oops_end_marker(); 385 add_taint(taint); 386 } 387 388 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) 389 { 390 struct slowpath_args args; 391 392 args.fmt = fmt; 393 va_start(args.args, fmt); 394 warn_slowpath_common(file, line, __builtin_return_address(0), 395 TAINT_WARN, &args); 396 va_end(args.args); 397 } 398 EXPORT_SYMBOL(warn_slowpath_fmt); 399 400 void warn_slowpath_fmt_taint(const char *file, int line, 401 unsigned taint, const char *fmt, ...) 402 { 403 struct slowpath_args args; 404 405 args.fmt = fmt; 406 va_start(args.args, fmt); 407 warn_slowpath_common(file, line, __builtin_return_address(0), 408 taint, &args); 409 va_end(args.args); 410 } 411 EXPORT_SYMBOL(warn_slowpath_fmt_taint); 412 413 void warn_slowpath_null(const char *file, int line) 414 { 415 warn_slowpath_common(file, line, __builtin_return_address(0), 416 TAINT_WARN, NULL); 417 } 418 EXPORT_SYMBOL(warn_slowpath_null); 419 #endif 420 421 #ifdef CONFIG_CC_STACKPROTECTOR 422 423 /* 424 * Called when gcc's -fstack-protector feature is used, and 425 * gcc detects corruption of the on-stack canary value 426 */ 427 void __stack_chk_fail(void) 428 { 429 panic("stack-protector: Kernel stack is corrupted in: %p\n", 430 __builtin_return_address(0)); 431 } 432 EXPORT_SYMBOL(__stack_chk_fail); 433 434 #endif 435 436 core_param(panic, panic_timeout, int, 0644); 437 core_param(pause_on_oops, pause_on_oops, int, 0644); 438 439 static int __init oops_setup(char *s) 440 { 441 if (!s) 442 return -EINVAL; 443 if (!strcmp(s, "panic")) 444 panic_on_oops = 1; 445 return 0; 446 } 447 early_param("oops", oops_setup); 448