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/ftrace.h> 19 #include <linux/reboot.h> 20 #include <linux/delay.h> 21 #include <linux/kexec.h> 22 #include <linux/sched.h> 23 #include <linux/sysrq.h> 24 #include <linux/init.h> 25 #include <linux/nmi.h> 26 27 #define PANIC_TIMER_STEP 100 28 #define PANIC_BLINK_SPD 18 29 30 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE; 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 static bool crash_kexec_post_notifiers; 36 37 int panic_timeout = CONFIG_PANIC_TIMEOUT; 38 EXPORT_SYMBOL_GPL(panic_timeout); 39 40 ATOMIC_NOTIFIER_HEAD(panic_notifier_list); 41 42 EXPORT_SYMBOL(panic_notifier_list); 43 44 static long no_blink(int state) 45 { 46 return 0; 47 } 48 49 /* Returns how long it waited in ms */ 50 long (*panic_blink)(int state); 51 EXPORT_SYMBOL(panic_blink); 52 53 /* 54 * Stop ourself in panic -- architecture code may override this 55 */ 56 void __weak panic_smp_self_stop(void) 57 { 58 while (1) 59 cpu_relax(); 60 } 61 62 /** 63 * panic - halt the system 64 * @fmt: The text string to print 65 * 66 * Display a message, then perform cleanups. 67 * 68 * This function never returns. 69 */ 70 void panic(const char *fmt, ...) 71 { 72 static DEFINE_SPINLOCK(panic_lock); 73 static char buf[1024]; 74 va_list args; 75 long i, i_next = 0; 76 int state = 0; 77 78 /* 79 * Disable local interrupts. This will prevent panic_smp_self_stop 80 * from deadlocking the first cpu that invokes the panic, since 81 * there is nothing to prevent an interrupt handler (that runs 82 * after the panic_lock is acquired) from invoking panic again. 83 */ 84 local_irq_disable(); 85 86 /* 87 * It's possible to come here directly from a panic-assertion and 88 * not have preempt disabled. Some functions called from here want 89 * preempt to be disabled. No point enabling it later though... 90 * 91 * Only one CPU is allowed to execute the panic code from here. For 92 * multiple parallel invocations of panic, all other CPUs either 93 * stop themself or will wait until they are stopped by the 1st CPU 94 * with smp_send_stop(). 95 */ 96 if (!spin_trylock(&panic_lock)) 97 panic_smp_self_stop(); 98 99 console_verbose(); 100 bust_spinlocks(1); 101 va_start(args, fmt); 102 vsnprintf(buf, sizeof(buf), fmt, args); 103 va_end(args); 104 pr_emerg("Kernel panic - not syncing: %s\n", buf); 105 #ifdef CONFIG_DEBUG_BUGVERBOSE 106 /* 107 * Avoid nested stack-dumping if a panic occurs during oops processing 108 */ 109 if (!test_taint(TAINT_DIE) && oops_in_progress <= 1) 110 dump_stack(); 111 #endif 112 113 /* 114 * If we have crashed and we have a crash kernel loaded let it handle 115 * everything else. 116 * If we want to run this after calling panic_notifiers, pass 117 * the "crash_kexec_post_notifiers" option to the kernel. 118 */ 119 if (!crash_kexec_post_notifiers) 120 crash_kexec(NULL); 121 122 /* 123 * Note smp_send_stop is the usual smp shutdown function, which 124 * unfortunately means it may not be hardened to work in a panic 125 * situation. 126 */ 127 smp_send_stop(); 128 129 /* 130 * Run any panic handlers, including those that might need to 131 * add information to the kmsg dump output. 132 */ 133 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 134 135 kmsg_dump(KMSG_DUMP_PANIC); 136 137 /* 138 * If you doubt kdump always works fine in any situation, 139 * "crash_kexec_post_notifiers" offers you a chance to run 140 * panic_notifiers and dumping kmsg before kdump. 141 * Note: since some panic_notifiers can make crashed kernel 142 * more unstable, it can increase risks of the kdump failure too. 143 */ 144 crash_kexec(NULL); 145 146 bust_spinlocks(0); 147 148 if (!panic_blink) 149 panic_blink = no_blink; 150 151 if (panic_timeout > 0) { 152 /* 153 * Delay timeout seconds before rebooting the machine. 154 * We can't use the "normal" timers since we just panicked. 155 */ 156 pr_emerg("Rebooting in %d seconds..", panic_timeout); 157 158 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { 159 touch_nmi_watchdog(); 160 if (i >= i_next) { 161 i += panic_blink(state ^= 1); 162 i_next = i + 3600 / PANIC_BLINK_SPD; 163 } 164 mdelay(PANIC_TIMER_STEP); 165 } 166 } 167 if (panic_timeout != 0) { 168 /* 169 * This will not be a clean reboot, with everything 170 * shutting down. But if there is a chance of 171 * rebooting the system it will be rebooted. 172 */ 173 emergency_restart(); 174 } 175 #ifdef __sparc__ 176 { 177 extern int stop_a_enabled; 178 /* Make sure the user can actually press Stop-A (L1-A) */ 179 stop_a_enabled = 1; 180 pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n"); 181 } 182 #endif 183 #if defined(CONFIG_S390) 184 { 185 unsigned long caller; 186 187 caller = (unsigned long)__builtin_return_address(0); 188 disabled_wait(caller); 189 } 190 #endif 191 pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf); 192 local_irq_enable(); 193 for (i = 0; ; i += PANIC_TIMER_STEP) { 194 touch_softlockup_watchdog(); 195 if (i >= i_next) { 196 i += panic_blink(state ^= 1); 197 i_next = i + 3600 / PANIC_BLINK_SPD; 198 } 199 mdelay(PANIC_TIMER_STEP); 200 } 201 } 202 203 EXPORT_SYMBOL(panic); 204 205 206 struct tnt { 207 u8 bit; 208 char true; 209 char false; 210 }; 211 212 static const struct tnt tnts[] = { 213 { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, 214 { TAINT_FORCED_MODULE, 'F', ' ' }, 215 { TAINT_CPU_OUT_OF_SPEC, 'S', ' ' }, 216 { TAINT_FORCED_RMMOD, 'R', ' ' }, 217 { TAINT_MACHINE_CHECK, 'M', ' ' }, 218 { TAINT_BAD_PAGE, 'B', ' ' }, 219 { TAINT_USER, 'U', ' ' }, 220 { TAINT_DIE, 'D', ' ' }, 221 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, 222 { TAINT_WARN, 'W', ' ' }, 223 { TAINT_CRAP, 'C', ' ' }, 224 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' }, 225 { TAINT_OOT_MODULE, 'O', ' ' }, 226 { TAINT_UNSIGNED_MODULE, 'E', ' ' }, 227 { TAINT_SOFTLOCKUP, 'L', ' ' }, 228 }; 229 230 /** 231 * print_tainted - return a string to represent the kernel taint state. 232 * 233 * 'P' - Proprietary module has been loaded. 234 * 'F' - Module has been forcibly loaded. 235 * 'S' - SMP with CPUs not designed for SMP. 236 * 'R' - User forced a module unload. 237 * 'M' - System experienced a machine check exception. 238 * 'B' - System has hit bad_page. 239 * 'U' - Userspace-defined naughtiness. 240 * 'D' - Kernel has oopsed before 241 * 'A' - ACPI table overridden. 242 * 'W' - Taint on warning. 243 * 'C' - modules from drivers/staging are loaded. 244 * 'I' - Working around severe firmware bug. 245 * 'O' - Out-of-tree module has been loaded. 246 * 'E' - Unsigned module has been loaded. 247 * 248 * The string is overwritten by the next call to print_tainted(). 249 */ 250 const char *print_tainted(void) 251 { 252 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")]; 253 254 if (tainted_mask) { 255 char *s; 256 int i; 257 258 s = buf + sprintf(buf, "Tainted: "); 259 for (i = 0; i < ARRAY_SIZE(tnts); i++) { 260 const struct tnt *t = &tnts[i]; 261 *s++ = test_bit(t->bit, &tainted_mask) ? 262 t->true : t->false; 263 } 264 *s = 0; 265 } else 266 snprintf(buf, sizeof(buf), "Not tainted"); 267 268 return buf; 269 } 270 271 int test_taint(unsigned flag) 272 { 273 return test_bit(flag, &tainted_mask); 274 } 275 EXPORT_SYMBOL(test_taint); 276 277 unsigned long get_taint(void) 278 { 279 return tainted_mask; 280 } 281 282 /** 283 * add_taint: add a taint flag if not already set. 284 * @flag: one of the TAINT_* constants. 285 * @lockdep_ok: whether lock debugging is still OK. 286 * 287 * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for 288 * some notewortht-but-not-corrupting cases, it can be set to true. 289 */ 290 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok) 291 { 292 if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off()) 293 pr_warn("Disabling lock debugging due to kernel taint\n"); 294 295 set_bit(flag, &tainted_mask); 296 } 297 EXPORT_SYMBOL(add_taint); 298 299 static void spin_msec(int msecs) 300 { 301 int i; 302 303 for (i = 0; i < msecs; i++) { 304 touch_nmi_watchdog(); 305 mdelay(1); 306 } 307 } 308 309 /* 310 * It just happens that oops_enter() and oops_exit() are identically 311 * implemented... 312 */ 313 static void do_oops_enter_exit(void) 314 { 315 unsigned long flags; 316 static int spin_counter; 317 318 if (!pause_on_oops) 319 return; 320 321 spin_lock_irqsave(&pause_on_oops_lock, flags); 322 if (pause_on_oops_flag == 0) { 323 /* This CPU may now print the oops message */ 324 pause_on_oops_flag = 1; 325 } else { 326 /* We need to stall this CPU */ 327 if (!spin_counter) { 328 /* This CPU gets to do the counting */ 329 spin_counter = pause_on_oops; 330 do { 331 spin_unlock(&pause_on_oops_lock); 332 spin_msec(MSEC_PER_SEC); 333 spin_lock(&pause_on_oops_lock); 334 } while (--spin_counter); 335 pause_on_oops_flag = 0; 336 } else { 337 /* This CPU waits for a different one */ 338 while (spin_counter) { 339 spin_unlock(&pause_on_oops_lock); 340 spin_msec(1); 341 spin_lock(&pause_on_oops_lock); 342 } 343 } 344 } 345 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 346 } 347 348 /* 349 * Return true if the calling CPU is allowed to print oops-related info. 350 * This is a bit racy.. 351 */ 352 int oops_may_print(void) 353 { 354 return pause_on_oops_flag == 0; 355 } 356 357 /* 358 * Called when the architecture enters its oops handler, before it prints 359 * anything. If this is the first CPU to oops, and it's oopsing the first 360 * time then let it proceed. 361 * 362 * This is all enabled by the pause_on_oops kernel boot option. We do all 363 * this to ensure that oopses don't scroll off the screen. It has the 364 * side-effect of preventing later-oopsing CPUs from mucking up the display, 365 * too. 366 * 367 * It turns out that the CPU which is allowed to print ends up pausing for 368 * the right duration, whereas all the other CPUs pause for twice as long: 369 * once in oops_enter(), once in oops_exit(). 370 */ 371 void oops_enter(void) 372 { 373 tracing_off(); 374 /* can't trust the integrity of the kernel anymore: */ 375 debug_locks_off(); 376 do_oops_enter_exit(); 377 } 378 379 /* 380 * 64-bit random ID for oopses: 381 */ 382 static u64 oops_id; 383 384 static int init_oops_id(void) 385 { 386 if (!oops_id) 387 get_random_bytes(&oops_id, sizeof(oops_id)); 388 else 389 oops_id++; 390 391 return 0; 392 } 393 late_initcall(init_oops_id); 394 395 void print_oops_end_marker(void) 396 { 397 init_oops_id(); 398 pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id); 399 } 400 401 /* 402 * Called when the architecture exits its oops handler, after printing 403 * everything. 404 */ 405 void oops_exit(void) 406 { 407 do_oops_enter_exit(); 408 print_oops_end_marker(); 409 kmsg_dump(KMSG_DUMP_OOPS); 410 } 411 412 #ifdef WANT_WARN_ON_SLOWPATH 413 struct slowpath_args { 414 const char *fmt; 415 va_list args; 416 }; 417 418 static void warn_slowpath_common(const char *file, int line, void *caller, 419 unsigned taint, struct slowpath_args *args) 420 { 421 disable_trace_on_warning(); 422 423 pr_warn("------------[ cut here ]------------\n"); 424 pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n", 425 raw_smp_processor_id(), current->pid, file, line, caller); 426 427 if (args) 428 vprintk(args->fmt, args->args); 429 430 print_modules(); 431 dump_stack(); 432 print_oops_end_marker(); 433 /* Just a warning, don't kill lockdep. */ 434 add_taint(taint, LOCKDEP_STILL_OK); 435 } 436 437 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) 438 { 439 struct slowpath_args args; 440 441 args.fmt = fmt; 442 va_start(args.args, fmt); 443 warn_slowpath_common(file, line, __builtin_return_address(0), 444 TAINT_WARN, &args); 445 va_end(args.args); 446 } 447 EXPORT_SYMBOL(warn_slowpath_fmt); 448 449 void warn_slowpath_fmt_taint(const char *file, int line, 450 unsigned taint, const char *fmt, ...) 451 { 452 struct slowpath_args args; 453 454 args.fmt = fmt; 455 va_start(args.args, fmt); 456 warn_slowpath_common(file, line, __builtin_return_address(0), 457 taint, &args); 458 va_end(args.args); 459 } 460 EXPORT_SYMBOL(warn_slowpath_fmt_taint); 461 462 void warn_slowpath_null(const char *file, int line) 463 { 464 warn_slowpath_common(file, line, __builtin_return_address(0), 465 TAINT_WARN, NULL); 466 } 467 EXPORT_SYMBOL(warn_slowpath_null); 468 #endif 469 470 #ifdef CONFIG_CC_STACKPROTECTOR 471 472 /* 473 * Called when gcc's -fstack-protector feature is used, and 474 * gcc detects corruption of the on-stack canary value 475 */ 476 __visible void __stack_chk_fail(void) 477 { 478 panic("stack-protector: Kernel stack is corrupted in: %p\n", 479 __builtin_return_address(0)); 480 } 481 EXPORT_SYMBOL(__stack_chk_fail); 482 483 #endif 484 485 core_param(panic, panic_timeout, int, 0644); 486 core_param(pause_on_oops, pause_on_oops, int, 0644); 487 488 static int __init setup_crash_kexec_post_notifiers(char *s) 489 { 490 crash_kexec_post_notifiers = true; 491 return 0; 492 } 493 early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers); 494 495 static int __init oops_setup(char *s) 496 { 497 if (!s) 498 return -EINVAL; 499 if (!strcmp(s, "panic")) 500 panic_on_oops = 1; 501 return 0; 502 } 503 early_param("oops", oops_setup); 504