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 int panic_on_oops; 28 static unsigned long tainted_mask; 29 static int pause_on_oops; 30 static int pause_on_oops_flag; 31 static DEFINE_SPINLOCK(pause_on_oops_lock); 32 33 int panic_timeout; 34 35 ATOMIC_NOTIFIER_HEAD(panic_notifier_list); 36 37 EXPORT_SYMBOL(panic_notifier_list); 38 39 static long no_blink(long time) 40 { 41 return 0; 42 } 43 44 /* Returns how long it waited in ms */ 45 long (*panic_blink)(long time); 46 EXPORT_SYMBOL(panic_blink); 47 48 /** 49 * panic - halt the system 50 * @fmt: The text string to print 51 * 52 * Display a message, then perform cleanups. 53 * 54 * This function never returns. 55 */ 56 NORET_TYPE void panic(const char * fmt, ...) 57 { 58 static char buf[1024]; 59 va_list args; 60 long i; 61 62 /* 63 * It's possible to come here directly from a panic-assertion and 64 * not have preempt disabled. Some functions called from here want 65 * preempt to be disabled. No point enabling it later though... 66 */ 67 preempt_disable(); 68 69 bust_spinlocks(1); 70 va_start(args, fmt); 71 vsnprintf(buf, sizeof(buf), fmt, args); 72 va_end(args); 73 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); 74 #ifdef CONFIG_DEBUG_BUGVERBOSE 75 dump_stack(); 76 #endif 77 78 /* 79 * If we have crashed and we have a crash kernel loaded let it handle 80 * everything else. 81 * Do we want to call this before we try to display a message? 82 */ 83 crash_kexec(NULL); 84 85 kmsg_dump(KMSG_DUMP_PANIC); 86 87 /* 88 * Note smp_send_stop is the usual smp shutdown function, which 89 * unfortunately means it may not be hardened to work in a panic 90 * situation. 91 */ 92 smp_send_stop(); 93 94 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 95 96 bust_spinlocks(0); 97 98 if (!panic_blink) 99 panic_blink = no_blink; 100 101 if (panic_timeout > 0) { 102 /* 103 * Delay timeout seconds before rebooting the machine. 104 * We can't use the "normal" timers since we just panicked. 105 */ 106 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout); 107 108 for (i = 0; i < panic_timeout*1000; ) { 109 touch_nmi_watchdog(); 110 i += panic_blink(i); 111 mdelay(1); 112 i++; 113 } 114 /* 115 * This will not be a clean reboot, with everything 116 * shutting down. But if there is a chance of 117 * rebooting the system it will be rebooted. 118 */ 119 emergency_restart(); 120 } 121 #ifdef __sparc__ 122 { 123 extern int stop_a_enabled; 124 /* Make sure the user can actually press Stop-A (L1-A) */ 125 stop_a_enabled = 1; 126 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); 127 } 128 #endif 129 #if defined(CONFIG_S390) 130 { 131 unsigned long caller; 132 133 caller = (unsigned long)__builtin_return_address(0); 134 disabled_wait(caller); 135 } 136 #endif 137 local_irq_enable(); 138 for (i = 0; ; ) { 139 touch_softlockup_watchdog(); 140 i += panic_blink(i); 141 mdelay(1); 142 i++; 143 } 144 } 145 146 EXPORT_SYMBOL(panic); 147 148 149 struct tnt { 150 u8 bit; 151 char true; 152 char false; 153 }; 154 155 static const struct tnt tnts[] = { 156 { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, 157 { TAINT_FORCED_MODULE, 'F', ' ' }, 158 { TAINT_UNSAFE_SMP, 'S', ' ' }, 159 { TAINT_FORCED_RMMOD, 'R', ' ' }, 160 { TAINT_MACHINE_CHECK, 'M', ' ' }, 161 { TAINT_BAD_PAGE, 'B', ' ' }, 162 { TAINT_USER, 'U', ' ' }, 163 { TAINT_DIE, 'D', ' ' }, 164 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, 165 { TAINT_WARN, 'W', ' ' }, 166 { TAINT_CRAP, 'C', ' ' }, 167 }; 168 169 /** 170 * print_tainted - return a string to represent the kernel taint state. 171 * 172 * 'P' - Proprietary module has been loaded. 173 * 'F' - Module has been forcibly loaded. 174 * 'S' - SMP with CPUs not designed for SMP. 175 * 'R' - User forced a module unload. 176 * 'M' - System experienced a machine check exception. 177 * 'B' - System has hit bad_page. 178 * 'U' - Userspace-defined naughtiness. 179 * 'D' - Kernel has oopsed before 180 * 'A' - ACPI table overridden. 181 * 'W' - Taint on warning. 182 * 'C' - modules from drivers/staging are loaded. 183 * 184 * The string is overwritten by the next call to print_tainted(). 185 */ 186 const char *print_tainted(void) 187 { 188 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1]; 189 190 if (tainted_mask) { 191 char *s; 192 int i; 193 194 s = buf + sprintf(buf, "Tainted: "); 195 for (i = 0; i < ARRAY_SIZE(tnts); i++) { 196 const struct tnt *t = &tnts[i]; 197 *s++ = test_bit(t->bit, &tainted_mask) ? 198 t->true : t->false; 199 } 200 *s = 0; 201 } else 202 snprintf(buf, sizeof(buf), "Not tainted"); 203 204 return buf; 205 } 206 207 int test_taint(unsigned flag) 208 { 209 return test_bit(flag, &tainted_mask); 210 } 211 EXPORT_SYMBOL(test_taint); 212 213 unsigned long get_taint(void) 214 { 215 return tainted_mask; 216 } 217 218 void add_taint(unsigned flag) 219 { 220 /* 221 * Can't trust the integrity of the kernel anymore. 222 * We don't call directly debug_locks_off() because the issue 223 * is not necessarily serious enough to set oops_in_progress to 1 224 * Also we want to keep up lockdep for staging development and 225 * post-warning case. 226 */ 227 if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off()) 228 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n"); 229 230 set_bit(flag, &tainted_mask); 231 } 232 EXPORT_SYMBOL(add_taint); 233 234 static void spin_msec(int msecs) 235 { 236 int i; 237 238 for (i = 0; i < msecs; i++) { 239 touch_nmi_watchdog(); 240 mdelay(1); 241 } 242 } 243 244 /* 245 * It just happens that oops_enter() and oops_exit() are identically 246 * implemented... 247 */ 248 static void do_oops_enter_exit(void) 249 { 250 unsigned long flags; 251 static int spin_counter; 252 253 if (!pause_on_oops) 254 return; 255 256 spin_lock_irqsave(&pause_on_oops_lock, flags); 257 if (pause_on_oops_flag == 0) { 258 /* This CPU may now print the oops message */ 259 pause_on_oops_flag = 1; 260 } else { 261 /* We need to stall this CPU */ 262 if (!spin_counter) { 263 /* This CPU gets to do the counting */ 264 spin_counter = pause_on_oops; 265 do { 266 spin_unlock(&pause_on_oops_lock); 267 spin_msec(MSEC_PER_SEC); 268 spin_lock(&pause_on_oops_lock); 269 } while (--spin_counter); 270 pause_on_oops_flag = 0; 271 } else { 272 /* This CPU waits for a different one */ 273 while (spin_counter) { 274 spin_unlock(&pause_on_oops_lock); 275 spin_msec(1); 276 spin_lock(&pause_on_oops_lock); 277 } 278 } 279 } 280 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 281 } 282 283 /* 284 * Return true if the calling CPU is allowed to print oops-related info. 285 * This is a bit racy.. 286 */ 287 int oops_may_print(void) 288 { 289 return pause_on_oops_flag == 0; 290 } 291 292 /* 293 * Called when the architecture enters its oops handler, before it prints 294 * anything. If this is the first CPU to oops, and it's oopsing the first 295 * time then let it proceed. 296 * 297 * This is all enabled by the pause_on_oops kernel boot option. We do all 298 * this to ensure that oopses don't scroll off the screen. It has the 299 * side-effect of preventing later-oopsing CPUs from mucking up the display, 300 * too. 301 * 302 * It turns out that the CPU which is allowed to print ends up pausing for 303 * the right duration, whereas all the other CPUs pause for twice as long: 304 * once in oops_enter(), once in oops_exit(). 305 */ 306 void oops_enter(void) 307 { 308 tracing_off(); 309 /* can't trust the integrity of the kernel anymore: */ 310 debug_locks_off(); 311 do_oops_enter_exit(); 312 } 313 314 /* 315 * 64-bit random ID for oopses: 316 */ 317 static u64 oops_id; 318 319 static int init_oops_id(void) 320 { 321 if (!oops_id) 322 get_random_bytes(&oops_id, sizeof(oops_id)); 323 else 324 oops_id++; 325 326 return 0; 327 } 328 late_initcall(init_oops_id); 329 330 static void print_oops_end_marker(void) 331 { 332 init_oops_id(); 333 printk(KERN_WARNING "---[ end trace %016llx ]---\n", 334 (unsigned long long)oops_id); 335 } 336 337 /* 338 * Called when the architecture exits its oops handler, after printing 339 * everything. 340 */ 341 void oops_exit(void) 342 { 343 do_oops_enter_exit(); 344 print_oops_end_marker(); 345 kmsg_dump(KMSG_DUMP_OOPS); 346 } 347 348 #ifdef WANT_WARN_ON_SLOWPATH 349 struct slowpath_args { 350 const char *fmt; 351 va_list args; 352 }; 353 354 static void warn_slowpath_common(const char *file, int line, void *caller, struct slowpath_args *args) 355 { 356 const char *board; 357 358 printk(KERN_WARNING "------------[ cut here ]------------\n"); 359 printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller); 360 board = dmi_get_system_info(DMI_PRODUCT_NAME); 361 if (board) 362 printk(KERN_WARNING "Hardware name: %s\n", board); 363 364 if (args) 365 vprintk(args->fmt, args->args); 366 367 print_modules(); 368 dump_stack(); 369 print_oops_end_marker(); 370 add_taint(TAINT_WARN); 371 } 372 373 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) 374 { 375 struct slowpath_args args; 376 377 args.fmt = fmt; 378 va_start(args.args, fmt); 379 warn_slowpath_common(file, line, __builtin_return_address(0), &args); 380 va_end(args.args); 381 } 382 EXPORT_SYMBOL(warn_slowpath_fmt); 383 384 void warn_slowpath_null(const char *file, int line) 385 { 386 warn_slowpath_common(file, line, __builtin_return_address(0), NULL); 387 } 388 EXPORT_SYMBOL(warn_slowpath_null); 389 #endif 390 391 #ifdef CONFIG_CC_STACKPROTECTOR 392 393 /* 394 * Called when gcc's -fstack-protector feature is used, and 395 * gcc detects corruption of the on-stack canary value 396 */ 397 void __stack_chk_fail(void) 398 { 399 panic("stack-protector: Kernel stack is corrupted in: %p\n", 400 __builtin_return_address(0)); 401 } 402 EXPORT_SYMBOL(__stack_chk_fail); 403 404 #endif 405 406 core_param(panic, panic_timeout, int, 0644); 407 core_param(pause_on_oops, pause_on_oops, int, 0644); 408