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
  38 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
  39
  40 EXPORT_SYMBOL(panic_notifier_list);
  41
  42 static long no_blink(int state)
  43 {
  44         return 0;
  45 }
  46
  47 /* Returns how long it waited in ms */
  48 long (*panic_blink)(int state);
  49 EXPORT_SYMBOL(panic_blink);
  50
  51 /**
  52  *      panic - halt the system
  53  *      @fmt: The text string to print
  54  *
  55  *      Display a message, then perform cleanups.
  56  *
  57  *      This function never returns.
  58  */
  59 NORET_TYPE void panic(const char * fmt, ...)
  60 {
  61         static char buf[1024];
  62         va_list args;
  63         long i, i_next = 0;
  64         int state = 0;
  65
  66         /*
  67          * It's possible to come here directly from a panic-assertion and
  68          * not have preempt disabled. Some functions called from here want
  69          * preempt to be disabled. No point enabling it later though...
  70          */
  71         preempt_disable();
  72
  73         console_verbose();
  74         bust_spinlocks(1);
  75         va_start(args, fmt);
  76         vsnprintf(buf, sizeof(buf), fmt, args);
  77         va_end(args);
  78         printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
  79 #ifdef CONFIG_DEBUG_BUGVERBOSE
  80         dump_stack();
  81 #endif
  82
  83         /*
  84          * If we have crashed and we have a crash kernel loaded let it handle
  85          * everything else.
  86          * Do we want to call this before we try to display a message?
  87          */
  88         crash_kexec(NULL);
  89
  90         kmsg_dump(KMSG_DUMP_PANIC);
  91
  92         /*
  93          * Note smp_send_stop is the usual smp shutdown function, which
  94          * unfortunately means it may not be hardened to work in a panic
  95          * situation.
  96          */
  97         smp_send_stop();
  98
  99         atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 100
 101         bust_spinlocks(0);
 102
 103         if (!panic_blink)
 104                 panic_blink = no_blink;
 105
 106         if (panic_timeout > 0) {
 107                 /*
 108                  * Delay timeout seconds before rebooting the machine.
 109                  * We can't use the "normal" timers since we just panicked.
 110                  */
 111                 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
 112
 113                 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
 114                         touch_nmi_watchdog();
 115                         if (i >= i_next) {
 116                                 i += panic_blink(state ^= 1);
 117                                 i_next = i + 3600 / PANIC_BLINK_SPD;
 118                         }
 119                         mdelay(PANIC_TIMER_STEP);
 120                 }
 121                 /*
 122                  * This will not be a clean reboot, with everything
 123                  * shutting down.  But if there is a chance of
 124                  * rebooting the system it will be rebooted.
 125                  */
 126                 emergency_restart();
 127         }
 128 #ifdef __sparc__
 129         {
 130                 extern int stop_a_enabled;
 131                 /* Make sure the user can actually press Stop-A (L1-A) */
 132                 stop_a_enabled = 1;
 133                 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
 134         }
 135 #endif
 136 #if defined(CONFIG_S390)
 137         {
 138                 unsigned long caller;
 139
 140                 caller = (unsigned long)__builtin_return_address(0);
 141                 disabled_wait(caller);
 142         }
 143 #endif
 144         local_irq_enable();
 145         for (i = 0; ; i += PANIC_TIMER_STEP) {
 146                 touch_softlockup_watchdog();
 147                 if (i >= i_next) {
 148                         i += panic_blink(state ^= 1);
 149                         i_next = i + 3600 / PANIC_BLINK_SPD;
 150                 }
 151                 mdelay(PANIC_TIMER_STEP);
 152         }
 153 }
 154
 155 EXPORT_SYMBOL(panic);
 156
 157
 158 struct tnt {
 159         u8      bit;
 160         char    true;
 161         char    false;
 162 };
 163
 164 static const struct tnt tnts[] = {
 165         { TAINT_PROPRIETARY_MODULE,     'P', 'G' },
 166         { TAINT_FORCED_MODULE,          'F', ' ' },
 167         { TAINT_UNSAFE_SMP,             'S', ' ' },
 168         { TAINT_FORCED_RMMOD,           'R', ' ' },
 169         { TAINT_MACHINE_CHECK,          'M', ' ' },
 170         { TAINT_BAD_PAGE,               'B', ' ' },
 171         { TAINT_USER,                   'U', ' ' },
 172         { TAINT_DIE,                    'D', ' ' },
 173         { TAINT_OVERRIDDEN_ACPI_TABLE,  'A', ' ' },
 174         { TAINT_WARN,                   'W', ' ' },
 175         { TAINT_CRAP,                   'C', ' ' },
 176         { TAINT_FIRMWARE_WORKAROUND,    'I', ' ' },
 177 };
 178
 179 /**
 180  *      print_tainted - return a string to represent the kernel taint state.
 181  *
 182  *  'P' - Proprietary module has been loaded.
 183  *  'F' - Module has been forcibly loaded.
 184  *  'S' - SMP with CPUs not designed for SMP.
 185  *  'R' - User forced a module unload.
 186  *  'M' - System experienced a machine check exception.
 187  *  'B' - System has hit bad_page.
 188  *  'U' - Userspace-defined naughtiness.
 189  *  'D' - Kernel has oopsed before
 190  *  'A' - ACPI table overridden.
 191  *  'W' - Taint on warning.
 192  *  'C' - modules from drivers/staging are loaded.
 193  *  'I' - Working around severe firmware bug.
 194  *
 195  *      The string is overwritten by the next call to print_tainted().
 196  */
 197 const char *print_tainted(void)
 198 {
 199         static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
 200
 201         if (tainted_mask) {
 202                 char *s;
 203                 int i;
 204
 205                 s = buf + sprintf(buf, "Tainted: ");
 206                 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
 207                         const struct tnt *t = &tnts[i];
 208                         *s++ = test_bit(t->bit, &tainted_mask) ?
 209                                         t->true : t->false;
 210                 }
 211                 *s = 0;
 212         } else
 213                 snprintf(buf, sizeof(buf), "Not tainted");
 214
 215         return buf;
 216 }
 217
 218 int test_taint(unsigned flag)
 219 {
 220         return test_bit(flag, &tainted_mask);
 221 }
 222 EXPORT_SYMBOL(test_taint);
 223
 224 unsigned long get_taint(void)
 225 {
 226         return tainted_mask;
 227 }
 228
 229 void add_taint(unsigned flag)
 230 {
 231         /*
 232          * Can't trust the integrity of the kernel anymore.
 233          * We don't call directly debug_locks_off() because the issue
 234          * is not necessarily serious enough to set oops_in_progress to 1
 235          * Also we want to keep up lockdep for staging development and
 236          * post-warning case.
 237          */
 238         if (flag != TAINT_CRAP && flag != TAINT_WARN && __debug_locks_off())
 239                 printk(KERN_WARNING "Disabling lock debugging due to kernel taint\n");
 240
 241         set_bit(flag, &tainted_mask);
 242 }
 243 EXPORT_SYMBOL(add_taint);
 244
 245 static void spin_msec(int msecs)
 246 {
 247         int i;
 248
 249         for (i = 0; i < msecs; i++) {
 250                 touch_nmi_watchdog();
 251                 mdelay(1);
 252         }
 253 }
 254
 255 /*
 256  * It just happens that oops_enter() and oops_exit() are identically
 257  * implemented...
 258  */
 259 static void do_oops_enter_exit(void)
 260 {
 261         unsigned long flags;
 262         static int spin_counter;
 263
 264         if (!pause_on_oops)
 265                 return;
 266
 267         spin_lock_irqsave(&pause_on_oops_lock, flags);
 268         if (pause_on_oops_flag == 0) {
 269                 /* This CPU may now print the oops message */
 270                 pause_on_oops_flag = 1;
 271         } else {
 272                 /* We need to stall this CPU */
 273                 if (!spin_counter) {
 274                         /* This CPU gets to do the counting */
 275                         spin_counter = pause_on_oops;
 276                         do {
 277                                 spin_unlock(&pause_on_oops_lock);
 278                                 spin_msec(MSEC_PER_SEC);
 279                                 spin_lock(&pause_on_oops_lock);
 280                         } while (--spin_counter);
 281                         pause_on_oops_flag = 0;
 282                 } else {
 283                         /* This CPU waits for a different one */
 284                         while (spin_counter) {
 285                                 spin_unlock(&pause_on_oops_lock);
 286                                 spin_msec(1);
 287                                 spin_lock(&pause_on_oops_lock);
 288                         }
 289                 }
 290         }
 291         spin_unlock_irqrestore(&pause_on_oops_lock, flags);
 292 }
 293
 294 /*
 295  * Return true if the calling CPU is allowed to print oops-related info.
 296  * This is a bit racy..
 297  */
 298 int oops_may_print(void)
 299 {
 300         return pause_on_oops_flag == 0;
 301 }
 302
 303 /*
 304  * Called when the architecture enters its oops handler, before it prints
 305  * anything.  If this is the first CPU to oops, and it's oopsing the first
 306  * time then let it proceed.
 307  *
 308  * This is all enabled by the pause_on_oops kernel boot option.  We do all
 309  * this to ensure that oopses don't scroll off the screen.  It has the
 310  * side-effect of preventing later-oopsing CPUs from mucking up the display,
 311  * too.
 312  *
 313  * It turns out that the CPU which is allowed to print ends up pausing for
 314  * the right duration, whereas all the other CPUs pause for twice as long:
 315  * once in oops_enter(), once in oops_exit().
 316  */
 317 void oops_enter(void)
 318 {
 319         tracing_off();
 320         /* can't trust the integrity of the kernel anymore: */
 321         debug_locks_off();
 322         do_oops_enter_exit();
 323 }
 324
 325 /*
 326  * 64-bit random ID for oopses:
 327  */
 328 static u64 oops_id;
 329
 330 static int init_oops_id(void)
 331 {
 332         if (!oops_id)
 333                 get_random_bytes(&oops_id, sizeof(oops_id));
 334         else
 335                 oops_id++;
 336
 337         return 0;
 338 }
 339 late_initcall(init_oops_id);
 340
 341 void print_oops_end_marker(void)
 342 {
 343         init_oops_id();
 344         printk(KERN_WARNING "---[ end trace %016llx ]---\n",
 345                 (unsigned long long)oops_id);
 346 }
 347
 348 /*
 349  * Called when the architecture exits its oops handler, after printing
 350  * everything.
 351  */
 352 void oops_exit(void)
 353 {
 354         do_oops_enter_exit();
 355         print_oops_end_marker();
 356         kmsg_dump(KMSG_DUMP_OOPS);
 357 }
 358
 359 #ifdef WANT_WARN_ON_SLOWPATH
 360 struct slowpath_args {
 361         const char *fmt;
 362         va_list args;
 363 };
 364
 365 static void warn_slowpath_common(const char *file, int line, void *caller,
 366                                  unsigned taint, struct slowpath_args *args)
 367 {
 368         const char *board;
 369
 370         printk(KERN_WARNING "------------[ cut here ]------------\n");
 371         printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
 372         board = dmi_get_system_info(DMI_PRODUCT_NAME);
 373         if (board)
 374                 printk(KERN_WARNING "Hardware name: %s\n", board);
 375
 376         if (args)
 377                 vprintk(args->fmt, args->args);
 378
 379         print_modules();
 380         dump_stack();
 381         print_oops_end_marker();
 382         add_taint(taint);
 383 }
 384
 385 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
 386 {
 387         struct slowpath_args args;
 388
 389         args.fmt = fmt;
 390         va_start(args.args, fmt);
 391         warn_slowpath_common(file, line, __builtin_return_address(0),
 392                              TAINT_WARN, &args);
 393         va_end(args.args);
 394 }
 395 EXPORT_SYMBOL(warn_slowpath_fmt);
 396
 397 void warn_slowpath_fmt_taint(const char *file, int line,
 398                              unsigned taint, const char *fmt, ...)
 399 {
 400         struct slowpath_args args;
 401
 402         args.fmt = fmt;
 403         va_start(args.args, fmt);
 404         warn_slowpath_common(file, line, __builtin_return_address(0),
 405                              taint, &args);
 406         va_end(args.args);
 407 }
 408 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
 409
 410 void warn_slowpath_null(const char *file, int line)
 411 {
 412         warn_slowpath_common(file, line, __builtin_return_address(0),
 413                              TAINT_WARN, NULL);
 414 }
 415 EXPORT_SYMBOL(warn_slowpath_null);
 416 #endif
 417
 418 #ifdef CONFIG_CC_STACKPROTECTOR
 419
 420 /*
 421  * Called when gcc's -fstack-protector feature is used, and
 422  * gcc detects corruption of the on-stack canary value
 423  */
 424 void __stack_chk_fail(void)
 425 {
 426         panic("stack-protector: Kernel stack is corrupted in: %p\n",
 427                 __builtin_return_address(0));
 428 }
 429 EXPORT_SYMBOL(__stack_chk_fail);
 430
 431 #endif
 432
 433 core_param(panic, panic_timeout, int, 0644);
 434 core_param(pause_on_oops, pause_on_oops, int, 0644);