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 kmsg_dump(KMSG_DUMP_PANIC); 79 /* 80 * If we have crashed and we have a crash kernel loaded let it handle 81 * everything else. 82 * Do we want to call this before we try to display a message? 83 */ 84 crash_kexec(NULL); 85 86 /* 87 * Note smp_send_stop is the usual smp shutdown function, which 88 * unfortunately means it may not be hardened to work in a panic 89 * situation. 90 */ 91 smp_send_stop(); 92 93 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 94 95 bust_spinlocks(0); 96 97 if (!panic_blink) 98 panic_blink = no_blink; 99 100 if (panic_timeout > 0) { 101 /* 102 * Delay timeout seconds before rebooting the machine. 103 * We can't use the "normal" timers since we just panicked. 104 */ 105 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout); 106 107 for (i = 0; i < panic_timeout*1000; ) { 108 touch_nmi_watchdog(); 109 i += panic_blink(i); 110 mdelay(1); 111 i++; 112 } 113 /* 114 * This will not be a clean reboot, with everything 115 * shutting down. But if there is a chance of 116 * rebooting the system it will be rebooted. 117 */ 118 emergency_restart(); 119 } 120 #ifdef __sparc__ 121 { 122 extern int stop_a_enabled; 123 /* Make sure the user can actually press Stop-A (L1-A) */ 124 stop_a_enabled = 1; 125 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); 126 } 127 #endif 128 #if defined(CONFIG_S390) 129 { 130 unsigned long caller; 131 132 caller = (unsigned long)__builtin_return_address(0); 133 disabled_wait(caller); 134 } 135 #endif 136 local_irq_enable(); 137 for (i = 0; ; ) { 138 touch_softlockup_watchdog(); 139 i += panic_blink(i); 140 mdelay(1); 141 i++; 142 } 143 } 144 145 EXPORT_SYMBOL(panic); 146 147 148 struct tnt { 149 u8 bit; 150 char true; 151 char false; 152 }; 153 154 static const struct tnt tnts[] = { 155 { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, 156 { TAINT_FORCED_MODULE, 'F', ' ' }, 157 { TAINT_UNSAFE_SMP, 'S', ' ' }, 158 { TAINT_FORCED_RMMOD, 'R', ' ' }, 159 { TAINT_MACHINE_CHECK, 'M', ' ' }, 160 { TAINT_BAD_PAGE, 'B', ' ' }, 161 { TAINT_USER, 'U', ' ' }, 162 { TAINT_DIE, 'D', ' ' }, 163 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, 164 { TAINT_WARN, 'W', ' ' }, 165 { TAINT_CRAP, 'C', ' ' }, 166 }; 167 168 /** 169 * print_tainted - return a string to represent the kernel taint state. 170 * 171 * 'P' - Proprietary module has been loaded. 172 * 'F' - Module has been forcibly loaded. 173 * 'S' - SMP with CPUs not designed for SMP. 174 * 'R' - User forced a module unload. 175 * 'M' - System experienced a machine check exception. 176 * 'B' - System has hit bad_page. 177 * 'U' - Userspace-defined naughtiness. 178 * 'D' - Kernel has oopsed before 179 * 'A' - ACPI table overridden. 180 * 'W' - Taint on warning. 181 * 'C' - modules from drivers/staging are loaded. 182 * 183 * The string is overwritten by the next call to print_tainted(). 184 */ 185 const char *print_tainted(void) 186 { 187 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1]; 188 189 if (tainted_mask) { 190 char *s; 191 int i; 192 193 s = buf + sprintf(buf, "Tainted: "); 194 for (i = 0; i < ARRAY_SIZE(tnts); i++) { 195 const struct tnt *t = &tnts[i]; 196 *s++ = test_bit(t->bit, &tainted_mask) ? 197 t->true : t->false; 198 } 199 *s = 0; 200 } else 201 snprintf(buf, sizeof(buf), "Not tainted"); 202 203 return buf; 204 } 205 206 int test_taint(unsigned flag) 207 { 208 return test_bit(flag, &tainted_mask); 209 } 210 EXPORT_SYMBOL(test_taint); 211 212 unsigned long get_taint(void) 213 { 214 return tainted_mask; 215 } 216 217 void add_taint(unsigned flag) 218 { 219 /* 220 * Can't trust the integrity of the kernel anymore. 221 * We don't call directly debug_locks_off() because the issue 222 * is not necessarily serious enough to set oops_in_progress to 1 223 * Also we want to keep up lockdep for staging development and 224 * post-warning case. 225 */ 226 if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off()) 227 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n"); 228 229 set_bit(flag, &tainted_mask); 230 } 231 EXPORT_SYMBOL(add_taint); 232 233 static void spin_msec(int msecs) 234 { 235 int i; 236 237 for (i = 0; i < msecs; i++) { 238 touch_nmi_watchdog(); 239 mdelay(1); 240 } 241 } 242 243 /* 244 * It just happens that oops_enter() and oops_exit() are identically 245 * implemented... 246 */ 247 static void do_oops_enter_exit(void) 248 { 249 unsigned long flags; 250 static int spin_counter; 251 252 if (!pause_on_oops) 253 return; 254 255 spin_lock_irqsave(&pause_on_oops_lock, flags); 256 if (pause_on_oops_flag == 0) { 257 /* This CPU may now print the oops message */ 258 pause_on_oops_flag = 1; 259 } else { 260 /* We need to stall this CPU */ 261 if (!spin_counter) { 262 /* This CPU gets to do the counting */ 263 spin_counter = pause_on_oops; 264 do { 265 spin_unlock(&pause_on_oops_lock); 266 spin_msec(MSEC_PER_SEC); 267 spin_lock(&pause_on_oops_lock); 268 } while (--spin_counter); 269 pause_on_oops_flag = 0; 270 } else { 271 /* This CPU waits for a different one */ 272 while (spin_counter) { 273 spin_unlock(&pause_on_oops_lock); 274 spin_msec(1); 275 spin_lock(&pause_on_oops_lock); 276 } 277 } 278 } 279 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 280 } 281 282 /* 283 * Return true if the calling CPU is allowed to print oops-related info. 284 * This is a bit racy.. 285 */ 286 int oops_may_print(void) 287 { 288 return pause_on_oops_flag == 0; 289 } 290 291 /* 292 * Called when the architecture enters its oops handler, before it prints 293 * anything. If this is the first CPU to oops, and it's oopsing the first 294 * time then let it proceed. 295 * 296 * This is all enabled by the pause_on_oops kernel boot option. We do all 297 * this to ensure that oopses don't scroll off the screen. It has the 298 * side-effect of preventing later-oopsing CPUs from mucking up the display, 299 * too. 300 * 301 * It turns out that the CPU which is allowed to print ends up pausing for 302 * the right duration, whereas all the other CPUs pause for twice as long: 303 * once in oops_enter(), once in oops_exit(). 304 */ 305 void oops_enter(void) 306 { 307 tracing_off(); 308 /* can't trust the integrity of the kernel anymore: */ 309 debug_locks_off(); 310 do_oops_enter_exit(); 311 } 312 313 /* 314 * 64-bit random ID for oopses: 315 */ 316 static u64 oops_id; 317 318 static int init_oops_id(void) 319 { 320 if (!oops_id) 321 get_random_bytes(&oops_id, sizeof(oops_id)); 322 else 323 oops_id++; 324 325 return 0; 326 } 327 late_initcall(init_oops_id); 328 329 static void print_oops_end_marker(void) 330 { 331 init_oops_id(); 332 printk(KERN_WARNING "---[ end trace %016llx ]---\n", 333 (unsigned long long)oops_id); 334 } 335 336 /* 337 * Called when the architecture exits its oops handler, after printing 338 * everything. 339 */ 340 void oops_exit(void) 341 { 342 do_oops_enter_exit(); 343 print_oops_end_marker(); 344 kmsg_dump(KMSG_DUMP_OOPS); 345 } 346 347 #ifdef WANT_WARN_ON_SLOWPATH 348 struct slowpath_args { 349 const char *fmt; 350 va_list args; 351 }; 352 353 static void warn_slowpath_common(const char *file, int line, void *caller, struct slowpath_args *args) 354 { 355 const char *board; 356 357 printk(KERN_WARNING "------------[ cut here ]------------\n"); 358 printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller); 359 board = dmi_get_system_info(DMI_PRODUCT_NAME); 360 if (board) 361 printk(KERN_WARNING "Hardware name: %s\n", board); 362 363 if (args) 364 vprintk(args->fmt, args->args); 365 366 print_modules(); 367 dump_stack(); 368 print_oops_end_marker(); 369 add_taint(TAINT_WARN); 370 } 371 372 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) 373 { 374 struct slowpath_args args; 375 376 args.fmt = fmt; 377 va_start(args.args, fmt); 378 warn_slowpath_common(file, line, __builtin_return_address(0), &args); 379 va_end(args.args); 380 } 381 EXPORT_SYMBOL(warn_slowpath_fmt); 382 383 void warn_slowpath_null(const char *file, int line) 384 { 385 warn_slowpath_common(file, line, __builtin_return_address(0), NULL); 386 } 387 EXPORT_SYMBOL(warn_slowpath_null); 388 #endif 389 390 #ifdef CONFIG_CC_STACKPROTECTOR 391 392 /* 393 * Called when gcc's -fstack-protector feature is used, and 394 * gcc detects corruption of the on-stack canary value 395 */ 396 void __stack_chk_fail(void) 397 { 398 panic("stack-protector: Kernel stack is corrupted in: %p\n", 399 __builtin_return_address(0)); 400 } 401 EXPORT_SYMBOL(__stack_chk_fail); 402 403 #endif 404 405 core_param(panic, panic_timeout, int, 0644); 406 core_param(pause_on_oops, pause_on_oops, int, 0644); 407