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/exynos-ss.h>
  26 #include <asm/core_regs.h>
  27 #include "sched/sched.h"
  28 #include <linux/console.h>
  29
  30 #define PANIC_TIMER_STEP 100
  31 #define PANIC_BLINK_SPD 18
  32 #if defined(CONFIG_SOC_EXYNOS5422) || defined(CONFIG_SOC_EXYNOS5430)
  33 extern void show_exynos_pmu(void);
  34 #endif
  35 #if defined(CONFIG_SOC_EXYNOS5422) || defined(CONFIG_SOC_EXYNOS5430)
  36 extern void show_exynos_cmu(void);
  37 #endif
  38
  39 /* Machine specific panic information string */
  40 char *mach_panic_string;
  41
  42 /* Machine specific panic information string */
  43 char *mach_panic_string;
  44
  45 int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
  46 static unsigned long tainted_mask;
  47 static int pause_on_oops;
  48 static int pause_on_oops_flag;
  49 static DEFINE_SPINLOCK(pause_on_oops_lock);
  50
  51 #ifndef CONFIG_PANIC_TIMEOUT
  52 #define CONFIG_PANIC_TIMEOUT 0
  53 #endif
  54 int panic_timeout = CONFIG_PANIC_TIMEOUT;
  55 EXPORT_SYMBOL_GPL(panic_timeout);
  56
  57 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
  58
  59 EXPORT_SYMBOL(panic_notifier_list);
  60
  61 static long no_blink(int state)
  62 {
  63         return 0;
  64 }
  65
  66 /* Returns how long it waited in ms */
  67 long (*panic_blink)(int state);
  68 EXPORT_SYMBOL(panic_blink);
  69
  70 /*
  71  * Stop ourself in panic -- architecture code may override this
  72  */
  73 void __weak panic_smp_self_stop(void)
  74 {
  75         while (1)
  76                 cpu_relax();
  77 }
  78
  79 /**
  80  *      panic - halt the system
  81  *      @fmt: The text string to print
  82  *
  83  *      Display a message, then perform cleanups.
  84  *
  85  *      This function never returns.
  86  */
  87 void panic(const char *fmt, ...)
  88 {
  89         static DEFINE_SPINLOCK(panic_lock);
  90         static char buf[1024];
  91         va_list args;
  92         long i, i_next = 0;
  93         int state = 0;
  94
  95 #ifdef CONFIG_EXYNOS_CORESIGHT_ETM
  96         exynos_trace_stop();
  97 #endif
  98         /*
  99          * Disable local interrupts. This will prevent panic_smp_self_stop
 100          * from deadlocking the first cpu that invokes the panic, since
 101          * there is nothing to prevent an interrupt handler (that runs
 102          * after the panic_lock is acquired) from invoking panic again.
 103          */
 104         local_irq_disable();
 105
 106         /*
 107          * It's possible to come here directly from a panic-assertion and
 108          * not have preempt disabled. Some functions called from here want
 109          * preempt to be disabled. No point enabling it later though...
 110          *
 111          * Only one CPU is allowed to execute the panic code from here. For
 112          * multiple parallel invocations of panic, all other CPUs either
 113          * stop themself or will wait until they are stopped by the 1st CPU
 114          * with smp_send_stop().
 115          */
 116         if (!spin_trylock(&panic_lock))
 117                 panic_smp_self_stop();
 118
 119         console_verbose();
 120         bust_spinlocks(1);
 121         va_start(args, fmt);
 122         vsnprintf(buf, sizeof(buf), fmt, args);
 123         va_end(args);
 124         printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
 125
 126         exynos_ss_prepare_panic();
 127         exynos_ss_dump_panic();
 128 #ifdef CONFIG_DEBUG_BUGVERBOSE
 129         /*
 130          * Avoid nested stack-dumping if a panic occurs during oops processing
 131          */
 132         if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
 133                 dump_stack();
 134 #endif
 135
 136 #if defined(CONFIG_SOC_EXYNOS5422) || defined(CONFIG_SOC_EXYNOS5430)
 137         show_exynos_pmu();
 138 #endif
 139 #if defined(CONFIG_SOC_EXYNOS5422) || defined(CONFIG_SOC_EXYNOS5430)
 140         show_exynos_cmu();
 141 #endif
 142         sysrq_sched_debug_show();
 143
 144         /*
 145          * If we have crashed and we have a crash kernel loaded let it handle
 146          * everything else.
 147          * Do we want to call this before we try to display a message?
 148          */
 149         crash_kexec(NULL);
 150
 151         /*
 152          * Note smp_send_stop is the usual smp shutdown function, which
 153          * unfortunately means it may not be hardened to work in a panic
 154          * situation.
 155          */
 156         smp_send_stop();
 157
 158         kmsg_dump(KMSG_DUMP_PANIC);
 159
 160         exynos_cs_show_pcval();
 161
 162         atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 163
 164         exynos_ss_post_panic();
 165
 166         bust_spinlocks(0);
 167
 168         console_flush_on_panic();
 169
 170         if (!panic_blink)
 171                 panic_blink = no_blink;
 172
 173         if (panic_timeout > 0) {
 174                 /*
 175                  * Delay timeout seconds before rebooting the machine.
 176                  * We can't use the "normal" timers since we just panicked.
 177                  */
 178                 printk(KERN_EMERG "Rebooting in %d seconds..", panic_timeout);
 179
 180                 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
 181                         touch_nmi_watchdog();
 182                         if (i >= i_next) {
 183                                 i += panic_blink(state ^= 1);
 184                                 i_next = i + 3600 / PANIC_BLINK_SPD;
 185                         }
 186                         mdelay(PANIC_TIMER_STEP);
 187                 }
 188         }
 189         if (panic_timeout != 0) {
 190                 /*
 191                  * This will not be a clean reboot, with everything
 192                  * shutting down.  But if there is a chance of
 193                  * rebooting the system it will be rebooted.
 194                  */
 195                 emergency_restart();
 196         }
 197 #ifdef __sparc__
 198         {
 199                 extern int stop_a_enabled;
 200                 /* Make sure the user can actually press Stop-A (L1-A) */
 201                 stop_a_enabled = 1;
 202                 printk(KERN_EMERG "Press Stop-A (L1-A) to return to the boot prom\n");
 203         }
 204 #endif
 205 #if defined(CONFIG_S390)
 206         {
 207                 unsigned long caller;
 208
 209                 caller = (unsigned long)__builtin_return_address(0);
 210                 disabled_wait(caller);
 211         }
 212 #endif
 213         local_irq_enable();
 214         for (i = 0; ; i += PANIC_TIMER_STEP) {
 215                 touch_softlockup_watchdog();
 216                 if (i >= i_next) {
 217                         i += panic_blink(state ^= 1);
 218                         i_next = i + 3600 / PANIC_BLINK_SPD;
 219                 }
 220                 mdelay(PANIC_TIMER_STEP);
 221         }
 222 }
 223
 224 EXPORT_SYMBOL(panic);
 225
 226
 227 struct tnt {
 228         u8      bit;
 229         char    true;
 230         char    false;
 231 };
 232
 233 static const struct tnt tnts[] = {
 234         { TAINT_PROPRIETARY_MODULE,     'P', 'G' },
 235         { TAINT_FORCED_MODULE,          'F', ' ' },
 236         { TAINT_UNSAFE_SMP,             'S', ' ' },
 237         { TAINT_FORCED_RMMOD,           'R', ' ' },
 238         { TAINT_MACHINE_CHECK,          'M', ' ' },
 239         { TAINT_BAD_PAGE,               'B', ' ' },
 240         { TAINT_USER,                   'U', ' ' },
 241         { TAINT_DIE,                    'D', ' ' },
 242         { TAINT_OVERRIDDEN_ACPI_TABLE,  'A', ' ' },
 243         { TAINT_WARN,                   'W', ' ' },
 244         { TAINT_CRAP,                   'C', ' ' },
 245         { TAINT_FIRMWARE_WORKAROUND,    'I', ' ' },
 246         { TAINT_OOT_MODULE,             'O', ' ' },
 247 };
 248
 249 /**
 250  *      print_tainted - return a string to represent the kernel taint state.
 251  *
 252  *  'P' - Proprietary module has been loaded.
 253  *  'F' - Module has been forcibly loaded.
 254  *  'S' - SMP with CPUs not designed for SMP.
 255  *  'R' - User forced a module unload.
 256  *  'M' - System experienced a machine check exception.
 257  *  'B' - System has hit bad_page.
 258  *  'U' - Userspace-defined naughtiness.
 259  *  'D' - Kernel has oopsed before
 260  *  'A' - ACPI table overridden.
 261  *  'W' - Taint on warning.
 262  *  'C' - modules from drivers/staging are loaded.
 263  *  'I' - Working around severe firmware bug.
 264  *  'O' - Out-of-tree module has been loaded.
 265  *
 266  *      The string is overwritten by the next call to print_tainted().
 267  */
 268 const char *print_tainted(void)
 269 {
 270         static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ") + 1];
 271
 272         if (tainted_mask) {
 273                 char *s;
 274                 int i;
 275
 276                 s = buf + sprintf(buf, "Tainted: ");
 277                 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
 278                         const struct tnt *t = &tnts[i];
 279                         *s++ = test_bit(t->bit, &tainted_mask) ?
 280                                         t->true : t->false;
 281                 }
 282                 *s = 0;
 283         } else
 284                 snprintf(buf, sizeof(buf), "Not tainted");
 285
 286         return buf;
 287 }
 288
 289 int test_taint(unsigned flag)
 290 {
 291         return test_bit(flag, &tainted_mask);
 292 }
 293 EXPORT_SYMBOL(test_taint);
 294
 295 unsigned long get_taint(void)
 296 {
 297         return tainted_mask;
 298 }
 299
 300 /**
 301  * add_taint: add a taint flag if not already set.
 302  * @flag: one of the TAINT_* constants.
 303  * @lockdep_ok: whether lock debugging is still OK.
 304  *
 305  * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
 306  * some notewortht-but-not-corrupting cases, it can be set to true.
 307  */
 308 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
 309 {
 310         if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
 311                 printk(KERN_WARNING
 312                        "Disabling lock debugging due to kernel taint\n");
 313
 314         set_bit(flag, &tainted_mask);
 315 }
 316 EXPORT_SYMBOL(add_taint);
 317
 318 static void spin_msec(int msecs)
 319 {
 320         int i;
 321
 322         for (i = 0; i < msecs; i++) {
 323                 touch_nmi_watchdog();
 324                 mdelay(1);
 325         }
 326 }
 327
 328 /*
 329  * It just happens that oops_enter() and oops_exit() are identically
 330  * implemented...
 331  */
 332 static void do_oops_enter_exit(void)
 333 {
 334         unsigned long flags;
 335         static int spin_counter;
 336
 337         if (!pause_on_oops)
 338                 return;
 339
 340         spin_lock_irqsave(&pause_on_oops_lock, flags);
 341         if (pause_on_oops_flag == 0) {
 342                 /* This CPU may now print the oops message */
 343                 pause_on_oops_flag = 1;
 344         } else {
 345                 /* We need to stall this CPU */
 346                 if (!spin_counter) {
 347                         /* This CPU gets to do the counting */
 348                         spin_counter = pause_on_oops;
 349                         do {
 350                                 spin_unlock(&pause_on_oops_lock);
 351                                 spin_msec(MSEC_PER_SEC);
 352                                 spin_lock(&pause_on_oops_lock);
 353                         } while (--spin_counter);
 354                         pause_on_oops_flag = 0;
 355                 } else {
 356                         /* This CPU waits for a different one */
 357                         while (spin_counter) {
 358                                 spin_unlock(&pause_on_oops_lock);
 359                                 spin_msec(1);
 360                                 spin_lock(&pause_on_oops_lock);
 361                         }
 362                 }
 363         }
 364         spin_unlock_irqrestore(&pause_on_oops_lock, flags);
 365 }
 366
 367 /*
 368  * Return true if the calling CPU is allowed to print oops-related info.
 369  * This is a bit racy..
 370  */
 371 int oops_may_print(void)
 372 {
 373         return pause_on_oops_flag == 0;
 374 }
 375
 376 /*
 377  * Called when the architecture enters its oops handler, before it prints
 378  * anything.  If this is the first CPU to oops, and it's oopsing the first
 379  * time then let it proceed.
 380  *
 381  * This is all enabled by the pause_on_oops kernel boot option.  We do all
 382  * this to ensure that oopses don't scroll off the screen.  It has the
 383  * side-effect of preventing later-oopsing CPUs from mucking up the display,
 384  * too.
 385  *
 386  * It turns out that the CPU which is allowed to print ends up pausing for
 387  * the right duration, whereas all the other CPUs pause for twice as long:
 388  * once in oops_enter(), once in oops_exit().
 389  */
 390 void oops_enter(void)
 391 {
 392         tracing_off();
 393         /* can't trust the integrity of the kernel anymore: */
 394         debug_locks_off();
 395         do_oops_enter_exit();
 396 }
 397
 398 /*
 399  * 64-bit random ID for oopses:
 400  */
 401 static u64 oops_id;
 402
 403 static int init_oops_id(void)
 404 {
 405         if (!oops_id)
 406                 get_random_bytes(&oops_id, sizeof(oops_id));
 407         else
 408                 oops_id++;
 409
 410         return 0;
 411 }
 412 late_initcall(init_oops_id);
 413
 414 void print_oops_end_marker(void)
 415 {
 416         init_oops_id();
 417
 418         if (mach_panic_string)
 419                 printk(KERN_WARNING "Board Information: %s\n",
 420                        mach_panic_string);
 421
 422         printk(KERN_WARNING "---[ end trace %016llx ]---\n",
 423                 (unsigned long long)oops_id);
 424 }
 425
 426 /*
 427  * Called when the architecture exits its oops handler, after printing
 428  * everything.
 429  */
 430 void oops_exit(void)
 431 {
 432         do_oops_enter_exit();
 433         print_oops_end_marker();
 434         kmsg_dump(KMSG_DUMP_OOPS);
 435 }
 436
 437 #ifdef WANT_WARN_ON_SLOWPATH
 438 struct slowpath_args {
 439         const char *fmt;
 440         va_list args;
 441 };
 442
 443 static void warn_slowpath_common(const char *file, int line, void *caller,
 444                                  unsigned taint, struct slowpath_args *args)
 445 {
 446         printk(KERN_WARNING "------------[ cut here ]------------\n");
 447         printk(KERN_WARNING "WARNING: at %s:%d %pS()\n", file, line, caller);
 448
 449         if (args)
 450                 vprintk(args->fmt, args->args);
 451
 452         print_modules();
 453         dump_stack();
 454         print_oops_end_marker();
 455         /* Just a warning, don't kill lockdep. */
 456         add_taint(taint, LOCKDEP_STILL_OK);
 457 }
 458
 459 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
 460 {
 461         struct slowpath_args args;
 462
 463         args.fmt = fmt;
 464         va_start(args.args, fmt);
 465         warn_slowpath_common(file, line, __builtin_return_address(0),
 466                              TAINT_WARN, &args);
 467         va_end(args.args);
 468 }
 469 EXPORT_SYMBOL(warn_slowpath_fmt);
 470
 471 void warn_slowpath_fmt_taint(const char *file, int line,
 472                              unsigned taint, const char *fmt, ...)
 473 {
 474         struct slowpath_args args;
 475
 476         args.fmt = fmt;
 477         va_start(args.args, fmt);
 478         warn_slowpath_common(file, line, __builtin_return_address(0),
 479                              taint, &args);
 480         va_end(args.args);
 481 }
 482 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
 483
 484 void warn_slowpath_null(const char *file, int line)
 485 {
 486         warn_slowpath_common(file, line, __builtin_return_address(0),
 487                              TAINT_WARN, NULL);
 488 }
 489 EXPORT_SYMBOL(warn_slowpath_null);
 490 #endif
 491
 492 #ifdef CONFIG_CC_STACKPROTECTOR
 493
 494 /*
 495  * Called when gcc's -fstack-protector feature is used, and
 496  * gcc detects corruption of the on-stack canary value
 497  */
 498 void __stack_chk_fail(void)
 499 {
 500         panic("stack-protector: Kernel stack is corrupted in: %p\n",
 501                 __builtin_return_address(0));
 502 }
 503 EXPORT_SYMBOL(__stack_chk_fail);
 504
 505 #endif
 506
 507 core_param(panic, panic_timeout, int, 0644);
 508 core_param(pause_on_oops, pause_on_oops, int, 0644);
 509
 510 static int __init oops_setup(char *s)
 511 {
 512         if (!s)
 513                 return -EINVAL;
 514         if (!strcmp(s, "panic"))
 515                 panic_on_oops = 1;
 516         return 0;
 517 }
 518 early_param("oops", oops_setup);