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 { TAINT_OOT_MODULE, 'O', ' ' }, 181 }; 182 183 /** 184 * print_tainted - return a string to represent the kernel taint state. 185 * 186 * 'P' - Proprietary module has been loaded. 187 * 'F' - Module has been forcibly loaded. 188 * 'S' - SMP with CPUs not designed for SMP. 189 * 'R' - User forced a module unload. 190 * 'M' - System experienced a machine check exception. 191 * 'B' - System has hit bad_page. 192 * 'U' - Userspace-defined naughtiness. 193 * 'D' - Kernel has oopsed before 194 * 'A' - ACPI table overridden. 195 * 'W' - Taint on warning. 196 * 'C' - modules from drivers/staging are loaded. 197 * 'I' - Working around severe firmware bug. 198 * 'O' - Out-of-tree module has been loaded. 199 * 200 * The string is overwritten by the next call to print_tainted(). 201 */ 202 const char *print_tainted(void) 203 { 204 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1]; 205 206 if (tainted_mask) { 207 char *s; 208 int i; 209 210 s = buf + sprintf(buf, "Tainted: "); 211 for (i = 0; i < ARRAY_SIZE(tnts); i++) { 212 const struct tnt *t = &tnts[i]; 213 *s++ = test_bit(t->bit, &tainted_mask) ? 214 t->true : t->false; 215 } 216 *s = 0; 217 } else 218 snprintf(buf, sizeof(buf), "Not tainted"); 219 220 return buf; 221 } 222 223 int test_taint(unsigned flag) 224 { 225 return test_bit(flag, &tainted_mask); 226 } 227 EXPORT_SYMBOL(test_taint); 228 229 unsigned long get_taint(void) 230 { 231 return tainted_mask; 232 } 233 234 void add_taint(unsigned flag) 235 { 236 /* 237 * Can't trust the integrity of the kernel anymore. 238 * We don't call directly debug_locks_off() because the issue 239 * is not necessarily serious enough to set oops_in_progress to 1 240 * Also we want to keep up lockdep for staging/out-of-tree 241 * development and post-warning case. 242 */ 243 switch (flag) { 244 case TAINT_CRAP: 245 case TAINT_OOT_MODULE: 246 case TAINT_WARN: 247 case TAINT_FIRMWARE_WORKAROUND: 248 break; 249 250 default: 251 if (__debug_locks_off()) 252 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n"); 253 } 254 255 set_bit(flag, &tainted_mask); 256 } 257 EXPORT_SYMBOL(add_taint); 258 259 static void spin_msec(int msecs) 260 { 261 int i; 262 263 for (i = 0; i < msecs; i++) { 264 touch_nmi_watchdog(); 265 mdelay(1); 266 } 267 } 268 269 /* 270 * It just happens that oops_enter() and oops_exit() are identically 271 * implemented... 272 */ 273 static void do_oops_enter_exit(void) 274 { 275 unsigned long flags; 276 static int spin_counter; 277 278 if (!pause_on_oops) 279 return; 280 281 spin_lock_irqsave(&pause_on_oops_lock, flags); 282 if (pause_on_oops_flag == 0) { 283 /* This CPU may now print the oops message */ 284 pause_on_oops_flag = 1; 285 } else { 286 /* We need to stall this CPU */ 287 if (!spin_counter) { 288 /* This CPU gets to do the counting */ 289 spin_counter = pause_on_oops; 290 do { 291 spin_unlock(&pause_on_oops_lock); 292 spin_msec(MSEC_PER_SEC); 293 spin_lock(&pause_on_oops_lock); 294 } while (--spin_counter); 295 pause_on_oops_flag = 0; 296 } else { 297 /* This CPU waits for a different one */ 298 while (spin_counter) { 299 spin_unlock(&pause_on_oops_lock); 300 spin_msec(1); 301 spin_lock(&pause_on_oops_lock); 302 } 303 } 304 } 305 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 306 } 307 308 /* 309 * Return true if the calling CPU is allowed to print oops-related info. 310 * This is a bit racy.. 311 */ 312 int oops_may_print(void) 313 { 314 return pause_on_oops_flag == 0; 315 } 316 317 /* 318 * Called when the architecture enters its oops handler, before it prints 319 * anything. If this is the first CPU to oops, and it's oopsing the first 320 * time then let it proceed. 321 * 322 * This is all enabled by the pause_on_oops kernel boot option. We do all 323 * this to ensure that oopses don't scroll off the screen. It has the 324 * side-effect of preventing later-oopsing CPUs from mucking up the display, 325 * too. 326 * 327 * It turns out that the CPU which is allowed to print ends up pausing for 328 * the right duration, whereas all the other CPUs pause for twice as long: 329 * once in oops_enter(), once in oops_exit(). 330 */ 331 void oops_enter(void) 332 { 333 tracing_off(); 334 /* can't trust the integrity of the kernel anymore: */ 335 debug_locks_off(); 336 do_oops_enter_exit(); 337 } 338 339 /* 340 * 64-bit random ID for oopses: 341 */ 342 static u64 oops_id; 343 344 static int init_oops_id(void) 345 { 346 if (!oops_id) 347 get_random_bytes(&oops_id, sizeof(oops_id)); 348 else 349 oops_id++; 350 351 return 0; 352 } 353 late_initcall(init_oops_id); 354 355 void print_oops_end_marker(void) 356 { 357 init_oops_id(); 358 printk(KERN_WARNING "---[ end trace %016llx ]---\n", 359 (unsigned long long)oops_id); 360 } 361 362 /* 363 * Called when the architecture exits its oops handler, after printing 364 * everything. 365 */ 366 void oops_exit(void) 367 { 368 do_oops_enter_exit(); 369 print_oops_end_marker(); 370 kmsg_dump(KMSG_DUMP_OOPS); 371 } 372 373 #ifdef WANT_WARN_ON_SLOWPATH 374 struct slowpath_args { 375 const char *fmt; 376 va_list args; 377 }; 378 379 static void warn_slowpath_common(const char *file, int line, void *caller, 380 unsigned taint, struct slowpath_args *args) 381 { 382 const char *board; 383 384 printk(KERN_WARNING "------------[ cut here ]------------\n"); 385 printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller); 386 board = dmi_get_system_info(DMI_PRODUCT_NAME); 387 if (board) 388 printk(KERN_WARNING "Hardware name: %s\n", board); 389 390 if (args) 391 vprintk(args->fmt, args->args); 392 393 print_modules(); 394 dump_stack(); 395 print_oops_end_marker(); 396 add_taint(taint); 397 } 398 399 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) 400 { 401 struct slowpath_args args; 402 403 args.fmt = fmt; 404 va_start(args.args, fmt); 405 warn_slowpath_common(file, line, __builtin_return_address(0), 406 TAINT_WARN, &args); 407 va_end(args.args); 408 } 409 EXPORT_SYMBOL(warn_slowpath_fmt); 410 411 void warn_slowpath_fmt_taint(const char *file, int line, 412 unsigned taint, const char *fmt, ...) 413 { 414 struct slowpath_args args; 415 416 args.fmt = fmt; 417 va_start(args.args, fmt); 418 warn_slowpath_common(file, line, __builtin_return_address(0), 419 taint, &args); 420 va_end(args.args); 421 } 422 EXPORT_SYMBOL(warn_slowpath_fmt_taint); 423 424 void warn_slowpath_null(const char *file, int line) 425 { 426 warn_slowpath_common(file, line, __builtin_return_address(0), 427 TAINT_WARN, NULL); 428 } 429 EXPORT_SYMBOL(warn_slowpath_null); 430 #endif 431 432 #ifdef CONFIG_CC_STACKPROTECTOR 433 434 /* 435 * Called when gcc's -fstack-protector feature is used, and 436 * gcc detects corruption of the on-stack canary value 437 */ 438 void __stack_chk_fail(void) 439 { 440 panic("stack-protector: Kernel stack is corrupted in: %p\n", 441 __builtin_return_address(0)); 442 } 443 EXPORT_SYMBOL(__stack_chk_fail); 444 445 #endif 446 447 core_param(panic, panic_timeout, int, 0644); 448 core_param(pause_on_oops, pause_on_oops, int, 0644); 449 450 static int __init oops_setup(char *s) 451 { 452 if (!s) 453 return -EINVAL; 454 if (!strcmp(s, "panic")) 455 panic_on_oops = 1; 456 return 0; 457 } 458 early_param("oops", oops_setup); 459