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/kallsyms.h> 14 #include <linux/notifier.h> 15 #include <linux/module.h> 16 #include <linux/random.h> 17 #include <linux/reboot.h> 18 #include <linux/delay.h> 19 #include <linux/kexec.h> 20 #include <linux/sched.h> 21 #include <linux/sysrq.h> 22 #include <linux/init.h> 23 #include <linux/nmi.h> 24 #include <linux/dmi.h> 25 26 int panic_on_oops; 27 static unsigned long tainted_mask; 28 static int pause_on_oops; 29 static int pause_on_oops_flag; 30 static DEFINE_SPINLOCK(pause_on_oops_lock); 31 32 int panic_timeout; 33 34 ATOMIC_NOTIFIER_HEAD(panic_notifier_list); 35 36 EXPORT_SYMBOL(panic_notifier_list); 37 38 static long no_blink(long time) 39 { 40 return 0; 41 } 42 43 /* Returns how long it waited in ms */ 44 long (*panic_blink)(long time); 45 EXPORT_SYMBOL(panic_blink); 46 47 /** 48 * panic - halt the system 49 * @fmt: The text string to print 50 * 51 * Display a message, then perform cleanups. 52 * 53 * This function never returns. 54 */ 55 NORET_TYPE void panic(const char * fmt, ...) 56 { 57 static char buf[1024]; 58 va_list args; 59 long i; 60 61 /* 62 * It's possible to come here directly from a panic-assertion and 63 * not have preempt disabled. Some functions called from here want 64 * preempt to be disabled. No point enabling it later though... 65 */ 66 preempt_disable(); 67 68 bust_spinlocks(1); 69 va_start(args, fmt); 70 vsnprintf(buf, sizeof(buf), fmt, args); 71 va_end(args); 72 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); 73 #ifdef CONFIG_DEBUG_BUGVERBOSE 74 dump_stack(); 75 #endif 76 77 /* 78 * If we have crashed and we have a crash kernel loaded let it handle 79 * everything else. 80 * Do we want to call this before we try to display a message? 81 */ 82 crash_kexec(NULL); 83 84 /* 85 * Note smp_send_stop is the usual smp shutdown function, which 86 * unfortunately means it may not be hardened to work in a panic 87 * situation. 88 */ 89 smp_send_stop(); 90 91 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 92 93 if (!panic_blink) 94 panic_blink = no_blink; 95 96 if (panic_timeout > 0) { 97 /* 98 * Delay timeout seconds before rebooting the machine. 99 * We can't use the "normal" timers since we just panicked. 100 */ 101 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout); 102 103 for (i = 0; i < panic_timeout*1000; ) { 104 touch_nmi_watchdog(); 105 i += panic_blink(i); 106 mdelay(1); 107 i++; 108 } 109 /* 110 * This will not be a clean reboot, with everything 111 * shutting down. But if there is a chance of 112 * rebooting the system it will be rebooted. 113 */ 114 emergency_restart(); 115 } 116 #ifdef __sparc__ 117 { 118 extern int stop_a_enabled; 119 /* Make sure the user can actually press Stop-A (L1-A) */ 120 stop_a_enabled = 1; 121 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); 122 } 123 #endif 124 #if defined(CONFIG_S390) 125 { 126 unsigned long caller; 127 128 caller = (unsigned long)__builtin_return_address(0); 129 disabled_wait(caller); 130 } 131 #endif 132 local_irq_enable(); 133 for (i = 0; ; ) { 134 touch_softlockup_watchdog(); 135 i += panic_blink(i); 136 mdelay(1); 137 i++; 138 } 139 bust_spinlocks(0); 140 } 141 142 EXPORT_SYMBOL(panic); 143 144 145 struct tnt { 146 u8 bit; 147 char true; 148 char false; 149 }; 150 151 static const struct tnt tnts[] = { 152 { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, 153 { TAINT_FORCED_MODULE, 'F', ' ' }, 154 { TAINT_UNSAFE_SMP, 'S', ' ' }, 155 { TAINT_FORCED_RMMOD, 'R', ' ' }, 156 { TAINT_MACHINE_CHECK, 'M', ' ' }, 157 { TAINT_BAD_PAGE, 'B', ' ' }, 158 { TAINT_USER, 'U', ' ' }, 159 { TAINT_DIE, 'D', ' ' }, 160 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, 161 { TAINT_WARN, 'W', ' ' }, 162 { TAINT_CRAP, 'C', ' ' }, 163 }; 164 165 /** 166 * print_tainted - return a string to represent the kernel taint state. 167 * 168 * 'P' - Proprietary module has been loaded. 169 * 'F' - Module has been forcibly loaded. 170 * 'S' - SMP with CPUs not designed for SMP. 171 * 'R' - User forced a module unload. 172 * 'M' - System experienced a machine check exception. 173 * 'B' - System has hit bad_page. 174 * 'U' - Userspace-defined naughtiness. 175 * 'D' - Kernel has oopsed before 176 * 'A' - ACPI table overridden. 177 * 'W' - Taint on warning. 178 * 'C' - modules from drivers/staging are loaded. 179 * 180 * The string is overwritten by the next call to print_taint(). 181 */ 182 const char *print_tainted(void) 183 { 184 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1]; 185 186 if (tainted_mask) { 187 char *s; 188 int i; 189 190 s = buf + sprintf(buf, "Tainted: "); 191 for (i = 0; i < ARRAY_SIZE(tnts); i++) { 192 const struct tnt *t = &tnts[i]; 193 *s++ = test_bit(t->bit, &tainted_mask) ? 194 t->true : t->false; 195 } 196 *s = 0; 197 } else 198 snprintf(buf, sizeof(buf), "Not tainted"); 199 200 return buf; 201 } 202 203 int test_taint(unsigned flag) 204 { 205 return test_bit(flag, &tainted_mask); 206 } 207 EXPORT_SYMBOL(test_taint); 208 209 unsigned long get_taint(void) 210 { 211 return tainted_mask; 212 } 213 214 void add_taint(unsigned flag) 215 { 216 /* 217 * Can't trust the integrity of the kernel anymore. 218 * We don't call directly debug_locks_off() because the issue 219 * is not necessarily serious enough to set oops_in_progress to 1 220 * Also we want to keep up lockdep for staging development and 221 * post-warning case. 222 */ 223 if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off()) 224 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n"); 225 226 set_bit(flag, &tainted_mask); 227 } 228 EXPORT_SYMBOL(add_taint); 229 230 static void spin_msec(int msecs) 231 { 232 int i; 233 234 for (i = 0; i < msecs; i++) { 235 touch_nmi_watchdog(); 236 mdelay(1); 237 } 238 } 239 240 /* 241 * It just happens that oops_enter() and oops_exit() are identically 242 * implemented... 243 */ 244 static void do_oops_enter_exit(void) 245 { 246 unsigned long flags; 247 static int spin_counter; 248 249 if (!pause_on_oops) 250 return; 251 252 spin_lock_irqsave(&pause_on_oops_lock, flags); 253 if (pause_on_oops_flag == 0) { 254 /* This CPU may now print the oops message */ 255 pause_on_oops_flag = 1; 256 } else { 257 /* We need to stall this CPU */ 258 if (!spin_counter) { 259 /* This CPU gets to do the counting */ 260 spin_counter = pause_on_oops; 261 do { 262 spin_unlock(&pause_on_oops_lock); 263 spin_msec(MSEC_PER_SEC); 264 spin_lock(&pause_on_oops_lock); 265 } while (--spin_counter); 266 pause_on_oops_flag = 0; 267 } else { 268 /* This CPU waits for a different one */ 269 while (spin_counter) { 270 spin_unlock(&pause_on_oops_lock); 271 spin_msec(1); 272 spin_lock(&pause_on_oops_lock); 273 } 274 } 275 } 276 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 277 } 278 279 /* 280 * Return true if the calling CPU is allowed to print oops-related info. 281 * This is a bit racy.. 282 */ 283 int oops_may_print(void) 284 { 285 return pause_on_oops_flag == 0; 286 } 287 288 /* 289 * Called when the architecture enters its oops handler, before it prints 290 * anything. If this is the first CPU to oops, and it's oopsing the first 291 * time then let it proceed. 292 * 293 * This is all enabled by the pause_on_oops kernel boot option. We do all 294 * this to ensure that oopses don't scroll off the screen. It has the 295 * side-effect of preventing later-oopsing CPUs from mucking up the display, 296 * too. 297 * 298 * It turns out that the CPU which is allowed to print ends up pausing for 299 * the right duration, whereas all the other CPUs pause for twice as long: 300 * once in oops_enter(), once in oops_exit(). 301 */ 302 void oops_enter(void) 303 { 304 /* can't trust the integrity of the kernel anymore: */ 305 debug_locks_off(); 306 do_oops_enter_exit(); 307 } 308 309 /* 310 * 64-bit random ID for oopses: 311 */ 312 static u64 oops_id; 313 314 static int init_oops_id(void) 315 { 316 if (!oops_id) 317 get_random_bytes(&oops_id, sizeof(oops_id)); 318 else 319 oops_id++; 320 321 return 0; 322 } 323 late_initcall(init_oops_id); 324 325 static void print_oops_end_marker(void) 326 { 327 init_oops_id(); 328 printk(KERN_WARNING "---[ end trace %016llx ]---\n", 329 (unsigned long long)oops_id); 330 } 331 332 /* 333 * Called when the architecture exits its oops handler, after printing 334 * everything. 335 */ 336 void oops_exit(void) 337 { 338 do_oops_enter_exit(); 339 print_oops_end_marker(); 340 } 341 342 #ifdef WANT_WARN_ON_SLOWPATH 343 struct slowpath_args { 344 const char *fmt; 345 va_list args; 346 }; 347 348 static void warn_slowpath_common(const char *file, int line, void *caller, struct slowpath_args *args) 349 { 350 const char *board; 351 352 printk(KERN_WARNING "------------[ cut here ]------------\n"); 353 printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller); 354 board = dmi_get_system_info(DMI_PRODUCT_NAME); 355 if (board) 356 printk(KERN_WARNING "Hardware name: %s\n", board); 357 358 if (args) 359 vprintk(args->fmt, args->args); 360 361 print_modules(); 362 dump_stack(); 363 print_oops_end_marker(); 364 add_taint(TAINT_WARN); 365 } 366 367 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...) 368 { 369 struct slowpath_args args; 370 371 args.fmt = fmt; 372 va_start(args.args, fmt); 373 warn_slowpath_common(file, line, __builtin_return_address(0), &args); 374 va_end(args.args); 375 } 376 EXPORT_SYMBOL(warn_slowpath_fmt); 377 378 void warn_slowpath_null(const char *file, int line) 379 { 380 warn_slowpath_common(file, line, __builtin_return_address(0), NULL); 381 } 382 EXPORT_SYMBOL(warn_slowpath_null); 383 #endif 384 385 #ifdef CONFIG_CC_STACKPROTECTOR 386 387 /* 388 * Called when gcc's -fstack-protector feature is used, and 389 * gcc detects corruption of the on-stack canary value 390 */ 391 void __stack_chk_fail(void) 392 { 393 panic("stack-protector: Kernel stack is corrupted in: %p\n", 394 __builtin_return_address(0)); 395 } 396 EXPORT_SYMBOL(__stack_chk_fail); 397 398 #endif 399 400 core_param(panic, panic_timeout, int, 0644); 401 core_param(pause_on_oops, pause_on_oops, int, 0644); 402