kernel/panic.c

   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         if (panic_timeout != 0) {
 124                 /*
 125                  * This will not be a clean reboot, with everything
 126                  * shutting down.  But if there is a chance of
 127                  * rebooting the system it will be rebooted.
 128                  */
 129                 emergency_restart();
 130         }
 131 #ifdef __sparc__
 132         {
 133                 extern int stop_a_enabled;
 134                 /* Make sure the user can actually press Stop-A (L1-A) */
 135                 stop_a_enabled = 1;
 136                 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
 137         }
 138 #endif
 139 #if defined(CONFIG_S390)
 140         {
 141                 unsigned long caller;
 142
 143                 caller = (unsigned long)__builtin_return_address(0);
 144                 disabled_wait(caller);
 145         }
 146 #endif
 147         local_irq_enable();
 148         for (i = 0; ; i += PANIC_TIMER_STEP) {
 149                 touch_softlockup_watchdog();
 150                 if (i >= i_next) {
 151                         i += panic_blink(state ^= 1);
 152                         i_next = i + 3600 / PANIC_BLINK_SPD;
 153                 }
 154                 mdelay(PANIC_TIMER_STEP);
 155         }
 156 }
 157
 158 EXPORT_SYMBOL(panic);
 159
 160
 161 struct tnt {
 162         u8      bit;
 163         char    true;
 164         char    false;
 165 };
 166
 167 static const struct tnt tnts[] = {
 168         { TAINT_PROPRIETARY_MODULE,     'P', 'G' },
 169         { TAINT_FORCED_MODULE,          'F', ' ' },
 170         { TAINT_UNSAFE_SMP,             'S', ' ' },
 171         { TAINT_FORCED_RMMOD,           'R', ' ' },
 172         { TAINT_MACHINE_CHECK,          'M', ' ' },
 173         { TAINT_BAD_PAGE,               'B', ' ' },
 174         { TAINT_USER,                   'U', ' ' },
 175         { TAINT_DIE,                    'D', ' ' },
 176         { TAINT_OVERRIDDEN_ACPI_TABLE,  'A', ' ' },
 177         { TAINT_WARN,                   'W', ' ' },
 178         { TAINT_CRAP,                   'C', ' ' },
 179         { TAINT_FIRMWARE_WORKAROUND,    'I', ' ' },
 180 };
 181
 182 /**
 183  *      print_tainted - return a string to represent the kernel taint state.
 184  *
 185  *  'P' - Proprietary module has been loaded.
 186  *  'F' - Module has been forcibly loaded.
 187  *  'S' - SMP with CPUs not designed for SMP.
 188  *  'R' - User forced a module unload.
 189  *  'M' - System experienced a machine check exception.
 190  *  'B' - System has hit bad_page.
 191  *  'U' - Userspace-defined naughtiness.
 192  *  'D' - Kernel has oopsed before
 193  *  'A' - ACPI table overridden.
 194  *  'W' - Taint on warning.
 195  *  'C' - modules from drivers/staging are loaded.
 196  *  'I' - Working around severe firmware bug.
 197  *
 198  *      The string is overwritten by the next call to print_tainted().
 199  */
 200 const char *print_tainted(void)
 201 {
 202         static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
 203
 204         if (tainted_mask) {
 205                 char *s;
 206                 int i;
 207
 208                 s = buf + sprintf(buf, "Tainted: ");
 209                 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
 210                         const struct tnt *t = &tnts[i];
 211                         *s++ = test_bit(t->bit, &tainted_mask) ?
 212                                         t->true : t->false;
 213                 }
 214                 *s = 0;
 215         } else
 216                 snprintf(buf, sizeof(buf), "Not tainted");
 217
 218         return buf;
 219 }
 220
 221 int test_taint(unsigned flag)
 222 {
 223         return test_bit(flag, &tainted_mask);
 224 }
 225 EXPORT_SYMBOL(test_taint);
 226
 227 unsigned long get_taint(void)
 228 {
 229         return tainted_mask;
 230 }
 231
 232 void add_taint(unsigned flag)
 233 {
 234         /*
 235          * Can't trust the integrity of the kernel anymore.
 236          * We don't call directly debug_locks_off() because the issue
 237          * is not necessarily serious enough to set oops_in_progress to 1
 238          * Also we want to keep up lockdep for staging development and
 239          * post-warning case.
 240          */
 241         if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
 242                 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
 243
 244         set_bit(flag, &tainted_mask);
 245 }
 246 EXPORT_SYMBOL(add_taint);
 247
 248 static void spin_msec(int msecs)
 249 {
 250         int i;
 251
 252         for (i = 0; i < msecs; i++) {
 253                 touch_nmi_watchdog();
 254                 mdelay(1);
 255         }
 256 }
 257
 258 /*
 259  * It just happens that oops_enter() and oops_exit() are identically
 260  * implemented...
 261  */
 262 static void do_oops_enter_exit(void)
 263 {
 264         unsigned long flags;
 265         static int spin_counter;
 266
 267         if (!pause_on_oops)
 268                 return;
 269
 270         spin_lock_irqsave(&pause_on_oops_lock, flags);
 271         if (pause_on_oops_flag == 0) {
 272                 /* This CPU may now print the oops message */
 273                 pause_on_oops_flag = 1;
 274         } else {
 275                 /* We need to stall this CPU */
 276                 if (!spin_counter) {
 277                         /* This CPU gets to do the counting */
 278                         spin_counter = pause_on_oops;
 279                         do {
 280                                 spin_unlock(&pause_on_oops_lock);
 281                                 spin_msec(MSEC_PER_SEC);
 282                                 spin_lock(&pause_on_oops_lock);
 283                         } while (--spin_counter);
 284                         pause_on_oops_flag = 0;
 285                 } else {
 286                         /* This CPU waits for a different one */
 287                         while (spin_counter) {
 288                                 spin_unlock(&pause_on_oops_lock);
 289                                 spin_msec(1);
 290                                 spin_lock(&pause_on_oops_lock);
 291                         }
 292                 }
 293         }
 294         spin_unlock_irqrestore(&pause_on_oops_lock, flags);
 295 }
 296
 297 /*
 298  * Return true if the calling CPU is allowed to print oops-related info.
 299  * This is a bit racy..
 300  */
 301 int oops_may_print(void)
 302 {
 303         return pause_on_oops_flag == 0;
 304 }
 305
 306 /*
 307  * Called when the architecture enters its oops handler, before it prints
 308  * anything.  If this is the first CPU to oops, and it's oopsing the first
 309  * time then let it proceed.
 310  *
 311  * This is all enabled by the pause_on_oops kernel boot option.  We do all
 312  * this to ensure that oopses don't scroll off the screen.  It has the
 313  * side-effect of preventing later-oopsing CPUs from mucking up the display,
 314  * too.
 315  *
 316  * It turns out that the CPU which is allowed to print ends up pausing for
 317  * the right duration, whereas all the other CPUs pause for twice as long:
 318  * once in oops_enter(), once in oops_exit().
 319  */
 320 void oops_enter(void)
 321 {
 322         tracing_off();
 323         /* can't trust the integrity of the kernel anymore: */
 324         debug_locks_off();
 325         do_oops_enter_exit();
 326 }
 327
 328 /*
 329  * 64-bit random ID for oopses:
 330  */
 331 static u64 oops_id;
 332
 333 static int init_oops_id(void)
 334 {
 335         if (!oops_id)
 336                 get_random_bytes(&oops_id, sizeof(oops_id));
 337         else
 338                 oops_id++;
 339
 340         return 0;
 341 }
 342 late_initcall(init_oops_id);
 343
 344 void print_oops_end_marker(void)
 345 {
 346         init_oops_id();
 347         printk(KERN_WARNING "---[ end trace %016llx ]---\n",
 348                 (unsigned long long)oops_id);
 349 }
 350
 351 /*
 352  * Called when the architecture exits its oops handler, after printing
 353  * everything.
 354  */
 355 void oops_exit(void)
 356 {
 357         do_oops_enter_exit();
 358         print_oops_end_marker();
 359         kmsg_dump(KMSG_DUMP_OOPS);
 360 }
 361
 362 #ifdef WANT_WARN_ON_SLOWPATH
 363 struct slowpath_args {
 364         const char *fmt;
 365         va_list args;
 366 };
 367
 368 static void warn_slowpath_common(const char *file, int line, void *caller,
 369                                  unsigned taint, struct slowpath_args *args)
 370 {
 371         const char *board;
 372
 373         printk(KERN_WARNING "------------[ cut here ]------------\n");
 374         printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
 375         board = dmi_get_system_info(DMI_PRODUCT_NAME);
 376         if (board)
 377                 printk(KERN_WARNING "Hardware name: %s\n", board);
 378
 379         if (args)
 380                 vprintk(args->fmt, args->args);
 381
 382         print_modules();
 383         dump_stack();
 384         print_oops_end_marker();
 385         add_taint(taint);
 386 }
 387
 388 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
 389 {
 390         struct slowpath_args args;
 391
 392         args.fmt = fmt;
 393         va_start(args.args, fmt);
 394         warn_slowpath_common(file, line, __builtin_return_address(0),
 395                              TAINT_WARN, &args);
 396         va_end(args.args);
 397 }
 398 EXPORT_SYMBOL(warn_slowpath_fmt);
 399
 400 void warn_slowpath_fmt_taint(const char *file, int line,
 401                              unsigned taint, const char *fmt, ...)
 402 {
 403         struct slowpath_args args;
 404
 405         args.fmt = fmt;
 406         va_start(args.args, fmt);
 407         warn_slowpath_common(file, line, __builtin_return_address(0),
 408                              taint, &args);
 409         va_end(args.args);
 410 }
 411 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
 412
 413 void warn_slowpath_null(const char *file, int line)
 414 {
 415         warn_slowpath_common(file, line, __builtin_return_address(0),
 416                              TAINT_WARN, NULL);
 417 }
 418 EXPORT_SYMBOL(warn_slowpath_null);
 419 #endif
 420
 421 #ifdef CONFIG_CC_STACKPROTECTOR
 422
 423 /*
 424  * Called when gcc's -fstack-protector feature is used, and
 425  * gcc detects corruption of the on-stack canary value
 426  */
 427 void __stack_chk_fail(void)
 428 {
 429         panic("stack-protector: Kernel stack is corrupted in: %p\n",
 430                 __builtin_return_address(0));
 431 }
 432 EXPORT_SYMBOL(__stack_chk_fail);
 433
 434 #endif
 435
 436 core_param(panic, panic_timeout, int, 0644);
 437 core_param(pause_on_oops, pause_on_oops, int, 0644);
 438
 439 static int __init oops_setup(char *s)
 440 {
 441         if (!s)
 442                 return -EINVAL;
 443         if (!strcmp(s, "panic"))
 444                 panic_on_oops = 1;
 445         return 0;
 446 }
 447 early_param("oops", oops_setup);