Version:  2.0.40 2.2.26 2.4.37 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17

   /*
    *  linux/kernel/panic.c
    *
    *  Copyright (C) 1991, 1992  Linus Torvalds
    */
   
   /*
    * This function is used through-out the kernel (including mm and fs)
    * to indicate a major problem.
   */
  #include <linux/debug_locks.h>
  #include <linux/interrupt.h>
  #include <linux/kmsg_dump.h>
  #include <linux/kallsyms.h>
  #include <linux/notifier.h>
  #include <linux/module.h>
  #include <linux/random.h>
  #include <linux/ftrace.h>
  #include <linux/reboot.h>
  #include <linux/delay.h>
  #include <linux/kexec.h>
  #include <linux/sched.h>
  #include <linux/sysrq.h>
  #include <linux/init.h>
  #include <linux/nmi.h>
  
  #define PANIC_TIMER_STEP 100
  #define PANIC_BLINK_SPD 18
  
  int panic_on_oops = CONFIG_PANIC_ON_OOPS_VALUE;
  static unsigned long tainted_mask;
  static int pause_on_oops;
  static int pause_on_oops_flag;
  static DEFINE_SPINLOCK(pause_on_oops_lock);
  static bool crash_kexec_post_notifiers;
  
  int panic_timeout = CONFIG_PANIC_TIMEOUT;
  EXPORT_SYMBOL_GPL(panic_timeout);
  
  ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
  
  EXPORT_SYMBOL(panic_notifier_list);
  
  static long no_blink(int state)
  {
          return 0;
  }
  
  /* Returns how long it waited in ms */
  long (*panic_blink)(int state);
  EXPORT_SYMBOL(panic_blink);
  
  /*
   * Stop ourself in panic -- architecture code may override this
   */
  void __weak panic_smp_self_stop(void)
  {
          while (1)
                  cpu_relax();
  }
  
  /**
   *      panic - halt the system
   *      @fmt: The text string to print
   *
   *      Display a message, then perform cleanups.
   *
   *      This function never returns.
   */
  void panic(const char *fmt, ...)
  {
          static DEFINE_SPINLOCK(panic_lock);
          static char buf[1024];
          va_list args;
          long i, i_next = 0;
          int state = 0;
  
          /*
           * Disable local interrupts. This will prevent panic_smp_self_stop
           * from deadlocking the first cpu that invokes the panic, since
           * there is nothing to prevent an interrupt handler (that runs
           * after the panic_lock is acquired) from invoking panic again.
           */
          local_irq_disable();
  
          /*
           * It's possible to come here directly from a panic-assertion and
           * not have preempt disabled. Some functions called from here want
           * preempt to be disabled. No point enabling it later though...
           *
           * Only one CPU is allowed to execute the panic code from here. For
           * multiple parallel invocations of panic, all other CPUs either
           * stop themself or will wait until they are stopped by the 1st CPU
           * with smp_send_stop().
           */
          if (!spin_trylock(&panic_lock))
                  panic_smp_self_stop();
  
          console_verbose();
         bust_spinlocks(1);
         va_start(args, fmt);
         vsnprintf(buf, sizeof(buf), fmt, args);
         va_end(args);
         pr_emerg("Kernel panic - not syncing: %s\n", buf);
 #ifdef CONFIG_DEBUG_BUGVERBOSE
         /*
          * Avoid nested stack-dumping if a panic occurs during oops processing
          */
         if (!test_taint(TAINT_DIE) && oops_in_progress <= 1)
                 dump_stack();
 #endif
 
         /*
          * If we have crashed and we have a crash kernel loaded let it handle
          * everything else.
          * If we want to run this after calling panic_notifiers, pass
          * the "crash_kexec_post_notifiers" option to the kernel.
          */
         if (!crash_kexec_post_notifiers)
                 crash_kexec(NULL);
 
         /*
          * Note smp_send_stop is the usual smp shutdown function, which
          * unfortunately means it may not be hardened to work in a panic
          * situation.
          */
         smp_send_stop();
 
         /*
          * Run any panic handlers, including those that might need to
          * add information to the kmsg dump output.
          */
         atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 
         kmsg_dump(KMSG_DUMP_PANIC);
 
         /*
          * If you doubt kdump always works fine in any situation,
          * "crash_kexec_post_notifiers" offers you a chance to run
          * panic_notifiers and dumping kmsg before kdump.
          * Note: since some panic_notifiers can make crashed kernel
          * more unstable, it can increase risks of the kdump failure too.
          */
         crash_kexec(NULL);
 
         bust_spinlocks(0);
 
         if (!panic_blink)
                 panic_blink = no_blink;
 
         if (panic_timeout > 0) {
                 /*
                  * Delay timeout seconds before rebooting the machine.
                  * We can't use the "normal" timers since we just panicked.
                  */
                 pr_emerg("Rebooting in %d seconds..", panic_timeout);
 
                 for (i = 0; i < panic_timeout * 1000; i += PANIC_TIMER_STEP) {
                         touch_nmi_watchdog();
                         if (i >= i_next) {
                                 i += panic_blink(state ^= 1);
                                 i_next = i + 3600 / PANIC_BLINK_SPD;
                         }
                         mdelay(PANIC_TIMER_STEP);
                 }
         }
         if (panic_timeout != 0) {
                 /*
                  * This will not be a clean reboot, with everything
                  * shutting down.  But if there is a chance of
                  * rebooting the system it will be rebooted.
                  */
                 emergency_restart();
         }
 #ifdef __sparc__
         {
                 extern int stop_a_enabled;
                 /* Make sure the user can actually press Stop-A (L1-A) */
                 stop_a_enabled = 1;
                 pr_emerg("Press Stop-A (L1-A) to return to the boot prom\n");
         }
 #endif
 #if defined(CONFIG_S390)
         {
                 unsigned long caller;
 
                 caller = (unsigned long)__builtin_return_address(0);
                 disabled_wait(caller);
         }
 #endif
         pr_emerg("---[ end Kernel panic - not syncing: %s\n", buf);
         local_irq_enable();
         for (i = 0; ; i += PANIC_TIMER_STEP) {
                 touch_softlockup_watchdog();
                 if (i >= i_next) {
                         i += panic_blink(state ^= 1);
                         i_next = i + 3600 / PANIC_BLINK_SPD;
                 }
                 mdelay(PANIC_TIMER_STEP);
         }
 }
 
 EXPORT_SYMBOL(panic);
 
 
 struct tnt {
         u8      bit;
         char    true;
         char    false;
 };
 
 static const struct tnt tnts[] = {
         { TAINT_PROPRIETARY_MODULE,     'P', 'G' },
         { TAINT_FORCED_MODULE,          'F', ' ' },
         { TAINT_CPU_OUT_OF_SPEC,        'S', ' ' },
         { TAINT_FORCED_RMMOD,           'R', ' ' },
         { TAINT_MACHINE_CHECK,          'M', ' ' },
         { TAINT_BAD_PAGE,               'B', ' ' },
         { TAINT_USER,                   'U', ' ' },
         { TAINT_DIE,                    'D', ' ' },
         { TAINT_OVERRIDDEN_ACPI_TABLE,  'A', ' ' },
         { TAINT_WARN,                   'W', ' ' },
         { TAINT_CRAP,                   'C', ' ' },
         { TAINT_FIRMWARE_WORKAROUND,    'I', ' ' },
         { TAINT_OOT_MODULE,             'O', ' ' },
         { TAINT_UNSIGNED_MODULE,        'E', ' ' },
         { TAINT_SOFTLOCKUP,             'L', ' ' },
 };
 
 /**
  *      print_tainted - return a string to represent the kernel taint state.
  *
  *  'P' - Proprietary module has been loaded.
  *  'F' - Module has been forcibly loaded.
  *  'S' - SMP with CPUs not designed for SMP.
  *  'R' - User forced a module unload.
  *  'M' - System experienced a machine check exception.
  *  'B' - System has hit bad_page.
  *  'U' - Userspace-defined naughtiness.
  *  'D' - Kernel has oopsed before
  *  'A' - ACPI table overridden.
  *  'W' - Taint on warning.
  *  'C' - modules from drivers/staging are loaded.
  *  'I' - Working around severe firmware bug.
  *  'O' - Out-of-tree module has been loaded.
  *  'E' - Unsigned module has been loaded.
  *
  *      The string is overwritten by the next call to print_tainted().
  */
 const char *print_tainted(void)
 {
         static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];
 
         if (tainted_mask) {
                 char *s;
                 int i;
 
                 s = buf + sprintf(buf, "Tainted: ");
                 for (i = 0; i < ARRAY_SIZE(tnts); i++) {
                         const struct tnt *t = &tnts[i];
                         *s++ = test_bit(t->bit, &tainted_mask) ?
                                         t->true : t->false;
                 }
                 *s = 0;
         } else
                 snprintf(buf, sizeof(buf), "Not tainted");
 
         return buf;
 }
 
 int test_taint(unsigned flag)
 {
         return test_bit(flag, &tainted_mask);
 }
 EXPORT_SYMBOL(test_taint);
 
 unsigned long get_taint(void)
 {
         return tainted_mask;
 }
 
 /**
  * add_taint: add a taint flag if not already set.
  * @flag: one of the TAINT_* constants.
  * @lockdep_ok: whether lock debugging is still OK.
  *
  * If something bad has gone wrong, you'll want @lockdebug_ok = false, but for
  * some notewortht-but-not-corrupting cases, it can be set to true.
  */
 void add_taint(unsigned flag, enum lockdep_ok lockdep_ok)
 {
         if (lockdep_ok == LOCKDEP_NOW_UNRELIABLE && __debug_locks_off())
                 pr_warn("Disabling lock debugging due to kernel taint\n");
 
         set_bit(flag, &tainted_mask);
 }
 EXPORT_SYMBOL(add_taint);
 
 static void spin_msec(int msecs)
 {
         int i;
 
         for (i = 0; i < msecs; i++) {
                 touch_nmi_watchdog();
                 mdelay(1);
         }
 }
 
 /*
  * It just happens that oops_enter() and oops_exit() are identically
  * implemented...
  */
 static void do_oops_enter_exit(void)
 {
         unsigned long flags;
         static int spin_counter;
 
         if (!pause_on_oops)
                 return;
 
         spin_lock_irqsave(&pause_on_oops_lock, flags);
         if (pause_on_oops_flag == 0) {
                 /* This CPU may now print the oops message */
                 pause_on_oops_flag = 1;
         } else {
                 /* We need to stall this CPU */
                 if (!spin_counter) {
                         /* This CPU gets to do the counting */
                         spin_counter = pause_on_oops;
                         do {
                                 spin_unlock(&pause_on_oops_lock);
                                 spin_msec(MSEC_PER_SEC);
                                 spin_lock(&pause_on_oops_lock);
                         } while (--spin_counter);
                         pause_on_oops_flag = 0;
                 } else {
                         /* This CPU waits for a different one */
                         while (spin_counter) {
                                 spin_unlock(&pause_on_oops_lock);
                                 spin_msec(1);
                                 spin_lock(&pause_on_oops_lock);
                         }
                 }
         }
         spin_unlock_irqrestore(&pause_on_oops_lock, flags);
 }
 
 /*
  * Return true if the calling CPU is allowed to print oops-related info.
  * This is a bit racy..
  */
 int oops_may_print(void)
 {
         return pause_on_oops_flag == 0;
 }
 
 /*
  * Called when the architecture enters its oops handler, before it prints
  * anything.  If this is the first CPU to oops, and it's oopsing the first
  * time then let it proceed.
  *
  * This is all enabled by the pause_on_oops kernel boot option.  We do all
  * this to ensure that oopses don't scroll off the screen.  It has the
  * side-effect of preventing later-oopsing CPUs from mucking up the display,
  * too.
  *
  * It turns out that the CPU which is allowed to print ends up pausing for
  * the right duration, whereas all the other CPUs pause for twice as long:
  * once in oops_enter(), once in oops_exit().
  */
 void oops_enter(void)
 {
         tracing_off();
         /* can't trust the integrity of the kernel anymore: */
         debug_locks_off();
         do_oops_enter_exit();
 }
 
 /*
  * 64-bit random ID for oopses:
  */
 static u64 oops_id;
 
 static int init_oops_id(void)
 {
         if (!oops_id)
                 get_random_bytes(&oops_id, sizeof(oops_id));
         else
                 oops_id++;
 
         return 0;
 }
 late_initcall(init_oops_id);
 
 void print_oops_end_marker(void)
 {
         init_oops_id();
         pr_warn("---[ end trace %016llx ]---\n", (unsigned long long)oops_id);
 }
 
 /*
  * Called when the architecture exits its oops handler, after printing
  * everything.
  */
 void oops_exit(void)
 {
         do_oops_enter_exit();
         print_oops_end_marker();
         kmsg_dump(KMSG_DUMP_OOPS);
 }
 
 #ifdef WANT_WARN_ON_SLOWPATH
 struct slowpath_args {
         const char *fmt;
         va_list args;
 };
 
 static void warn_slowpath_common(const char *file, int line, void *caller,
                                  unsigned taint, struct slowpath_args *args)
 {
         disable_trace_on_warning();
 
         pr_warn("------------[ cut here ]------------\n");
         pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS()\n",
                 raw_smp_processor_id(), current->pid, file, line, caller);
 
         if (args)
                 vprintk(args->fmt, args->args);
 
         print_modules();
         dump_stack();
         print_oops_end_marker();
         /* Just a warning, don't kill lockdep. */
         add_taint(taint, LOCKDEP_STILL_OK);
 }
 
 void warn_slowpath_fmt(const char *file, int line, const char *fmt, ...)
 {
         struct slowpath_args args;
 
         args.fmt = fmt;
         va_start(args.args, fmt);
         warn_slowpath_common(file, line, __builtin_return_address(0),
                              TAINT_WARN, &args);
         va_end(args.args);
 }
 EXPORT_SYMBOL(warn_slowpath_fmt);
 
 void warn_slowpath_fmt_taint(const char *file, int line,
                              unsigned taint, const char *fmt, ...)
 {
         struct slowpath_args args;
 
         args.fmt = fmt;
         va_start(args.args, fmt);
         warn_slowpath_common(file, line, __builtin_return_address(0),
                              taint, &args);
         va_end(args.args);
 }
 EXPORT_SYMBOL(warn_slowpath_fmt_taint);
 
 void warn_slowpath_null(const char *file, int line)
 {
         warn_slowpath_common(file, line, __builtin_return_address(0),
                              TAINT_WARN, NULL);
 }
 EXPORT_SYMBOL(warn_slowpath_null);
 #endif
 
 #ifdef CONFIG_CC_STACKPROTECTOR
 
 /*
  * Called when gcc's -fstack-protector feature is used, and
  * gcc detects corruption of the on-stack canary value
  */
 __visible void __stack_chk_fail(void)
 {
         panic("stack-protector: Kernel stack is corrupted in: %p\n",
                 __builtin_return_address(0));
 }
 EXPORT_SYMBOL(__stack_chk_fail);
 
 #endif
 
 core_param(panic, panic_timeout, int, 0644);
 core_param(pause_on_oops, pause_on_oops, int, 0644);
 
 static int __init setup_crash_kexec_post_notifiers(char *s)
 {
         crash_kexec_post_notifiers = true;
         return 0;
 }
 early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);
 
 static int __init oops_setup(char *s)
 {
         if (!s)
                 return -EINVAL;
         if (!strcmp(s, "panic"))
                 panic_on_oops = 1;
         return 0;
 }
 early_param("oops", oops_setup);
 

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