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 * This will not be a clean reboot, with everything 124 * shutting down. But if there is a chance of 125 * rebooting the system it will be rebooted. 126 */ 127 emergency_restart(); 128 } 129 #ifdef __sparc__ 130 { 131 extern int stop_a_enabled; 132 /* Make sure the user can actually press Stop-A (L1-A) */ 133 stop_a_enabled = 1; 134 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); 135 } 136 #endif 137 #if defined(CONFIG_S390) 138 { 139 unsigned long caller; 140 141 caller = (unsigned long)__builtin_return_address(0); 142 disabled_wait(caller); 143 } 144 #endif 145 local_irq_enable(); 146 for (i = 0; ; i += PANIC_TIMER_STEP) { 147 touch_softlockup_watchdog(); 148 if (i >= i_next) { 149 i += panic_blink(state ^= 1); 150 i_next = i + 3600 / PANIC_BLINK_SPD; 151 } 152 mdelay(PANIC_TIMER_STEP); 153 } 154 } 155 156 EXPORT_SYMBOL(panic); 157 158 159 struct tnt { 160 u8 bit; 161 char true; 162 char false; 163 }; 164 165 static const struct tnt tnts[] = { 166 { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, 167 { TAINT_FORCED_MODULE, 'F', ' ' }, 168 { TAINT_UNSAFE_SMP, 'S', ' ' }, 169 { TAINT_FORCED_RMMOD, 'R', ' ' }, 170 { TAINT_MACHINE_CHECK, 'M', ' ' }, 171 { TAINT_BAD_PAGE, 'B', ' ' }, 172 { TAINT_USER, 'U', ' ' }, 173 { TAINT_DIE, 'D', ' ' }, 174 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, 175 { TAINT_WARN, 'W', ' ' }, 176 { TAINT_CRAP, 'C', ' ' }, 177 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' }, 178 }; 179 180 /** 181 * print_tainted - return a string to represent the kernel taint state. 182 * 183 * 'P' - Proprietary module has been loaded. 184 * 'F' - Module has been forcibly loaded. 185 * 'S' - SMP with CPUs not designed for SMP. 186 * 'R' - User forced a module unload. 187 * 'M' - System experienced a machine check exception. 188 * 'B' - System has hit bad_page. 189 * 'U' - Userspace-defined naughtiness. 190 * 'D' - Kernel has oopsed before 191 * 'A' - ACPI table overridden. 192 * 'W' - Taint on warning. 193 * 'C' - modules from drivers/staging are loaded. 194 * 'I' - Working around severe firmware bug. 195 * 196 * The string is overwritten by the next call to print_tainted(). 197 */ 198 const char *print_tainted(void) 199 { 200 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1]; 201 202 if (tainted_mask) { 203 char *s; 204 int i; 205 206 s = buf + sprintf(buf, "Tainted: "); 207 for (i = 0; i < ARRAY_SIZE(tnts); i++) { 208 const struct tnt *t = &tnts[i]; 209 *s++ = test_bit(t->bit, &tainted_mask) ? 210 t->true : t->false; 211 } 212 *s = 0; 213 } else 214 snprintf(buf, sizeof(buf), "Not tainted"); 215 216 return buf; 217 } 218 219 int test_taint(unsigned flag) 220 { 221 return test_bit(flag, &tainted_mask); 222 } 223 EXPORT_SYMBOL(test_taint); 224 225 unsigned long get_taint(void) 226 { 227 return tainted_mask; 228 } 229 230 void add_taint(unsigned flag) 231 { 232 /* 233 * Can't trust the integrity of the kernel anymore. 234 * We don't call directly debug_locks_off() because the issue 235 * is not necessarily serious enough to set oops_in_progress to 1 236 * Also we want to keep up lockdep for staging development and 237 * post-warning case. 238 */ 239 if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off()) 240 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n"); 241 242 set_bit(flag, &tainted_mask); 243 } 244 EXPORT_SYMBOL(add_taint); 245 246 static void spin_msec(int msecs) 247 { 248 int i; 249 250 for (i = 0; i < msecs; i++) { 251 touch_nmi_watchdog(); 252 mdelay(1); 253 } 254 } 255 256 /* 257 * It just happens that oops_enter() and oops_exit() are identically 258 * implemented... 259 */ 260 static void do_oops_enter_exit(void) 261 { 262 unsigned long flags; 263 static int spin_counter; 264 265 if (!pause_on_oops) 266 return; 267 268 spin_lock_irqsave(&pause_on_oops_lock, flags); 269 if (pause_on_oops_flag == 0) { 270 /* This CPU may now print the oops message */ 271 pause_on_oops_flag = 1; 272 } else { 273 /* We need to stall this CPU */ 274 if (!spin_counter) { 275 /* This CPU gets to do the counting */ 276 spin_counter = pause_on_oops; 277 do { 278 spin_unlock(&pause_on_oops_lock); 279 spin_msec(MSEC_PER_SEC); 280 spin_lock(&pause_on_oops_lock); 281 } while (--spin_counter); 282 pause_on_oops_flag = 0; 283 } else { 284 /* This CPU waits for a different one */ 285 while (spin_counter) { 286 spin_unlock(&pause_on_oops_lock); 287 spin_msec(1); 288 spin_lock(&pause_on_oops_lock); 289 } 290 } 291 } 292 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 293 } 294 295 /* 296 * Return true if the calling CPU is allowed to print oops-related info. 297 * This is a bit racy.. 298 */ 299 int oops_may_print(void) 300 { 301 return pause_on_oops_flag == 0; 302 } 303 304 /* 305 * Called when the architecture enters its oops handler, before it prints 306 * anything. If this is the first CPU to oops, and it's oopsing the first 307 * time then let it proceed. 308 * 309 * This is all enabled by the pause_on_oops kernel boot option. We do all 310 * this to ensure that oopses don't scroll off the screen. It has the 311 * side-effect of preventing later-oopsing CPUs from mucking up the display, 312 * too. 313 * 314 * It turns out that the CPU which is allowed to print ends up pausing for 315 * the right duration, whereas all the other CPUs pause for twice as long: 316 * once in oops_enter(), once in oops_exit(). 317 */ 318 void oops_enter(void) 319 { 320 tracing_off(); 321 /* can't trust the integrity of the kernel anymore: */ 322 debug_locks_off(); 323 do_oops_enter_exit(); 324 } 325 326 /* 327 * 64-bit random ID for oopses: 328 */ 329 static u64 oops_id; 330 331 static int init_oops_id(void) 332 { 333 if (!oops_id) 334 get_random_bytes(&oops_id, sizeof(oops_id)); 335 else 336 oops_id++; 337 338 return 0; 339 } 340 late_initcall(init_oops_id); 341 342 void print_oops_end_marker(void) 343 { 344 init_oops_id(); 345 printk(KERN_WARNING "---[ end trace %016llx ]---\n", 346 (unsigned long long)oops_id); 347 } 348 349 /* 350 * Called when the architecture exits its oops handler, after printing 351 * everything. 352 */ 353 void oops_exit(void) 354 { 355 do_oops_enter_exit(); 356 print_oops_end_marker(); 357 kmsg_dump(KMSG_DUMP_OOPS); 358 } 359 360 #ifdef WANT_WARN_ON_SLOWPATH 361 struct slowpath_args { 362 const char *fmt; 363 va_list args; 364 }; 365 366 static void warn_slowpath_common(const char *file, int line, void *caller, 367 unsigned taint, struct slowpath_args *args) 368 { 369 const char *board; 370 371 printk(KERN_WARNING "------------[ cut here ]------------\n"); 372 printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller); 373 board = dmi_get_system_info(DMI_PRODUCT_NAME); 374 if (board) 375 printk(KERN_WARNING "Hardware name: %s\n", board); 376 377 if (args) 378 vprintk(args->fmt, args->args); 379 380 print_modules(); 381 dump_stack(); 382 print_oops_end_marker(); 383 add_taint(taint); 384 } 385 386 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) 387 { 388 struct slowpath_args args; 389 390 args.fmt = fmt; 391 va_start(args.args, fmt); 392 warn_slowpath_common(file, line, __builtin_return_address(0), 393 TAINT_WARN, &args); 394 va_end(args.args); 395 } 396 EXPORT_SYMBOL(warn_slowpath_fmt); 397 398 void warn_slowpath_fmt_taint(const char *file, int line, 399 unsigned taint, 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, &args); 407 va_end(args.args); 408 } 409 EXPORT_SYMBOL(warn_slowpath_fmt_taint); 410 411 void warn_slowpath_null(const char *file, int line) 412 { 413 warn_slowpath_common(file, line, __builtin_return_address(0), 414 TAINT_WARN, NULL); 415 } 416 EXPORT_SYMBOL(warn_slowpath_null); 417 #endif 418 419 #ifdef CONFIG_CC_STACKPROTECTOR 420 421 /* 422 * Called when gcc's -fstack-protector feature is used, and 423 * gcc detects corruption of the on-stack canary value 424 */ 425 void __stack_chk_fail(void) 426 { 427 panic("stack-protector: Kernel stack is corrupted in: %p\n", 428 __builtin_return_address(0)); 429 } 430 EXPORT_SYMBOL(__stack_chk_fail); 431 432 #endif 433 434 core_param(panic, panic_timeout, int, 0644); 435 core_param(pause_on_oops, pause_on_oops, int, 0644); 436 437 static int __init oops_setup(char *s) 438 { 439 if (!s) 440 return -EINVAL; 441 if (!strcmp(s, "panic")) 442 panic_on_oops = 1; 443 return 0; 444 } 445 early_param("oops", oops_setup); 446