| 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); |