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                  * 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);