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 30int panic_on_oops; 31static unsigned long tainted_mask; 32static int pause_on_oops; 33static int pause_on_oops_flag; 34static DEFINE_SPINLOCK(pause_on_oops_lock); 35 36int panic_timeout; 37 38ATOMIC_NOTIFIER_HEAD(panic_notifier_list); 39 40EXPORT_SYMBOL(panic_notifier_list); 41 42static long no_blink(int state) 43{ 44 return 0; 45} 46 47/* Returns how long it waited in ms */ 48long (*panic_blink)(int state); 49EXPORT_SYMBOL(panic_blink); 50 51#ifdef CONFIG_CRASHLOG 52void nvram_store_crash(void); 53#endif 54 55/** 56 * panic - halt the system 57 * @fmt: The text string to print 58 * 59 * Display a message, then perform cleanups. 60 * 61 * This function never returns. 62 */ 63NORET_TYPE void panic(const char * fmt, ...) 64{ 65 static char buf[1024]; 66 va_list args; 67 long i, i_next = 0; 68 int state = 0; 69 70 /* 71 * It's possible to come here directly from a panic-assertion and 72 * not have preempt disabled. Some functions called from here want 73 * preempt to be disabled. No point enabling it later though... 74 */ 75 preempt_disable(); 76 77 console_verbose(); 78 bust_spinlocks(1); 79 va_start(args, fmt); 80 vsnprintf(buf, sizeof(buf), fmt, args); 81 va_end(args); 82#ifdef CONFIG_DUMP_PREV_OOPS_MSG 83 enable_oopsbuf(1); 84#endif 85 printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf); 86#ifdef CONFIG_DEBUG_BUGVERBOSE 87 dump_stack(); 88#endif 89 90 /* 91 * If we have crashed and we have a crash kernel loaded let it handle 92 * everything else. 93 * Do we want to call this before we try to display a message? 94 */ 95 crash_kexec(NULL); 96 97 kmsg_dump(KMSG_DUMP_PANIC); 98 99 /* 100 * Note smp_send_stop is the usual smp shutdown function, which 101 * unfortunately means it may not be hardened to work in a panic 102 * situation. 103 */ 104 smp_send_stop(); 105 106 atomic_notifier_call_chain(&panic_notifier_list, 0, buf); 107 108 bust_spinlocks(0); 109 110#ifdef CONFIG_CRASHLOG 111 nvram_store_crash(); 112#endif 113 114 if (!panic_blink) 115 panic_blink = no_blink; 116 117 if (panic_timeout > 0) { 118 /* 119 * Delay timeout seconds before rebooting the machine. 120 * We can't use the "normal" timers since we just panicked. 121 */ 122 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout); 123 124 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) { 125 touch_nmi_watchdog(); 126 if (i >= i_next) { 127 i += panic_blink(state ^= 1); 128 i_next = i + 3600 / PANIC_BLINK_SPD; 129 } 130 mdelay(PANIC_TIMER_STEP); 131 } 132 /* 133 * This will not be a clean reboot, with everything 134 * shutting down. But if there is a chance of 135 * rebooting the system it will be rebooted. 136 */ 137 emergency_restart(); 138 } 139#ifdef __sparc__ 140 { 141 extern int stop_a_enabled; 142 /* Make sure the user can actually press Stop-A (L1-A) */ 143 stop_a_enabled = 1; 144 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n"); 145 } 146#endif 147#if defined(CONFIG_S390) 148 { 149 unsigned long caller; 150 151 caller = (unsigned long)__builtin_return_address(0); 152 disabled_wait(caller); 153 } 154#endif 155 local_irq_enable(); 156 for (i = 0; ; i += PANIC_TIMER_STEP) { 157 touch_softlockup_watchdog(); 158 if (i >= i_next) { 159 i += panic_blink(state ^= 1); 160 i_next = i + 3600 / PANIC_BLINK_SPD; 161 } 162 mdelay(PANIC_TIMER_STEP); 163 } 164} 165 166EXPORT_SYMBOL(panic); 167 168 169struct tnt { 170 u8 bit; 171 char true; 172 char false; 173}; 174 175static const struct tnt tnts[] = { 176 { TAINT_PROPRIETARY_MODULE, 'P', 'G' }, 177 { TAINT_FORCED_MODULE, 'F', ' ' }, 178 { TAINT_UNSAFE_SMP, 'S', ' ' }, 179 { TAINT_FORCED_RMMOD, 'R', ' ' }, 180 { TAINT_MACHINE_CHECK, 'M', ' ' }, 181 { TAINT_BAD_PAGE, 'B', ' ' }, 182 { TAINT_USER, 'U', ' ' }, 183 { TAINT_DIE, 'D', ' ' }, 184 { TAINT_OVERRIDDEN_ACPI_TABLE, 'A', ' ' }, 185 { TAINT_WARN, 'W', ' ' }, 186 { TAINT_CRAP, 'C', ' ' }, 187 { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' }, 188}; 189 190/** 191 * print_tainted - return a string to represent the kernel taint state. 192 * 193 * 'P' - Proprietary module has been loaded. 194 * 'F' - Module has been forcibly loaded. 195 * 'S' - SMP with CPUs not designed for SMP. 196 * 'R' - User forced a module unload. 197 * 'M' - System experienced a machine check exception. 198 * 'B' - System has hit bad_page. 199 * 'U' - Userspace-defined naughtiness. 200 * 'D' - Kernel has oopsed before 201 * 'A' - ACPI table overridden. 202 * 'W' - Taint on warning. 203 * 'C' - modules from drivers/staging are loaded. 204 * 'I' - Working around severe firmware bug. 205 * 206 * The string is overwritten by the next call to print_tainted(). 207 */ 208const char *print_tainted(void) 209{ 210 static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1]; 211 212 if (tainted_mask) { 213 char *s; 214 int i; 215 216 s = buf + sprintf(buf, "Tainted: "); 217 for (i = 0; i < ARRAY_SIZE(tnts); i++) { 218 const struct tnt *t = &tnts[i]; 219 *s++ = test_bit(t->bit, &tainted_mask) ? 220 t->true : t->false; 221 } 222 *s = 0; 223 } else 224 snprintf(buf, sizeof(buf), "Not tainted"); 225 226 return buf; 227} 228 229int test_taint(unsigned flag) 230{ 231 return test_bit(flag, &tainted_mask); 232} 233EXPORT_SYMBOL(test_taint); 234 235unsigned long get_taint(void) 236{ 237 return tainted_mask; 238} 239 240void add_taint(unsigned flag) 241{ 242 /* 243 * Can't trust the integrity of the kernel anymore. 244 * We don't call directly debug_locks_off() because the issue 245 * is not necessarily serious enough to set oops_in_progress to 1 246 * Also we want to keep up lockdep for staging development and 247 * post-warning case. 248 */ 249 if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off()) 250 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n"); 251 252 set_bit(flag, &tainted_mask); 253} 254EXPORT_SYMBOL(add_taint); 255 256static void spin_msec(int msecs) 257{ 258 int i; 259 260 for (i = 0; i < msecs; i++) { 261 touch_nmi_watchdog(); 262 mdelay(1); 263 } 264} 265 266/* 267 * It just happens that oops_enter() and oops_exit() are identically 268 * implemented... 269 */ 270static void do_oops_enter_exit(void) 271{ 272 unsigned long flags; 273 static int spin_counter; 274 275 if (!pause_on_oops) 276 return; 277 278 spin_lock_irqsave(&pause_on_oops_lock, flags); 279 if (pause_on_oops_flag == 0) { 280 /* This CPU may now print the oops message */ 281 pause_on_oops_flag = 1; 282 } else { 283 /* We need to stall this CPU */ 284 if (!spin_counter) { 285 /* This CPU gets to do the counting */ 286 spin_counter = pause_on_oops; 287 do { 288 spin_unlock(&pause_on_oops_lock); 289 spin_msec(MSEC_PER_SEC); 290 spin_lock(&pause_on_oops_lock); 291 } while (--spin_counter); 292 pause_on_oops_flag = 0; 293 } else { 294 /* This CPU waits for a different one */ 295 while (spin_counter) { 296 spin_unlock(&pause_on_oops_lock); 297 spin_msec(1); 298 spin_lock(&pause_on_oops_lock); 299 } 300 } 301 } 302 spin_unlock_irqrestore(&pause_on_oops_lock, flags); 303} 304 305/* 306 * Return true if the calling CPU is allowed to print oops-related info. 307 * This is a bit racy.. 308 */ 309int oops_may_print(void) 310{ 311 return pause_on_oops_flag == 0; 312} 313 314/* 315 * Called when the architecture enters its oops handler, before it prints 316 * anything. If this is the first CPU to oops, and it's oopsing the first 317 * time then let it proceed. 318 * 319 * This is all enabled by the pause_on_oops kernel boot option. We do all 320 * this to ensure that oopses don't scroll off the screen. It has the 321 * side-effect of preventing later-oopsing CPUs from mucking up the display, 322 * too. 323 * 324 * It turns out that the CPU which is allowed to print ends up pausing for 325 * the right duration, whereas all the other CPUs pause for twice as long: 326 * once in oops_enter(), once in oops_exit(). 327 */ 328void oops_enter(void) 329{ 330 tracing_off(); 331 /* can't trust the integrity of the kernel anymore: */ 332 debug_locks_off(); 333 do_oops_enter_exit(); 334#ifdef CONFIG_DUMP_PREV_OOPS_MSG 335 enable_oopsbuf(1); 336#endif 337} 338 339/* 340 * 64-bit random ID for oopses: 341 */ 342static u64 oops_id; 343 344static 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} 353late_initcall(init_oops_id); 354 355void 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 */ 366void 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 374struct slowpath_args { 375 const char *fmt; 376 va_list args; 377}; 378 379static 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 399void 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} 409EXPORT_SYMBOL(warn_slowpath_fmt); 410 411void 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} 422EXPORT_SYMBOL(warn_slowpath_fmt_taint); 423 424void warn_slowpath_null(const char *file, int line) 425{ 426 warn_slowpath_common(file, line, __builtin_return_address(0), 427 TAINT_WARN, NULL); 428} 429EXPORT_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 */ 438void __stack_chk_fail(void) 439{ 440 panic("stack-protector: Kernel stack is corrupted in: %p\n", 441 __builtin_return_address(0)); 442} 443EXPORT_SYMBOL(__stack_chk_fail); 444 445#endif 446 447core_param(panic, panic_timeout, int, 0644); 448core_param(pause_on_oops, pause_on_oops, int, 0644); 449