FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_shutdown.c

     /*-
      * Copyright (c) 1986, 1988, 1991, 1993
      *      The Regents of the University of California.  All rights reserved.
      * (c) UNIX System Laboratories, Inc.
      * All or some portions of this file are derived from material licensed
      * to the University of California by American Telephone and Telegraph
      * Co. or Unix System Laboratories, Inc. and are reproduced herein with
      * the permission of UNIX System Laboratories, Inc.
      *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)kern_shutdown.c     8.3 (Berkeley) 1/21/94
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/11.1/sys/kern/kern_shutdown.c 313119 2017-02-03 00:54:27Z markj $");
    
    #include "opt_ddb.h"
    #include "opt_kdb.h"
    #include "opt_panic.h"
    #include "opt_sched.h"
    #include "opt_watchdog.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/bio.h>
    #include <sys/buf.h>
    #include <sys/conf.h>
    #include <sys/cons.h>
    #include <sys/eventhandler.h>
    #include <sys/filedesc.h>
    #include <sys/jail.h>
    #include <sys/kdb.h>
    #include <sys/kernel.h>
    #include <sys/kerneldump.h>
    #include <sys/kthread.h>
    #include <sys/ktr.h>
    #include <sys/malloc.h>
    #include <sys/mount.h>
    #include <sys/priv.h>
    #include <sys/proc.h>
    #include <sys/reboot.h>
    #include <sys/resourcevar.h>
    #include <sys/rwlock.h>
    #include <sys/sched.h>
    #include <sys/smp.h>
    #include <sys/sysctl.h>
    #include <sys/sysproto.h>
    #include <sys/vnode.h>
    #include <sys/watchdog.h>
    
    #include <ddb/ddb.h>
    
    #include <machine/cpu.h>
    #include <machine/dump.h>
    #include <machine/pcb.h>
    #include <machine/smp.h>
    
    #include <security/mac/mac_framework.h>
    
    #include <vm/vm.h>
    #include <vm/vm_object.h>
    #include <vm/vm_page.h>
    #include <vm/vm_pager.h>
    #include <vm/swap_pager.h>
    
    #include <sys/signalvar.h>
    
    static MALLOC_DEFINE(M_DUMPER, "dumper", "dumper block buffer");
    
    #ifndef PANIC_REBOOT_WAIT_TIME
    #define PANIC_REBOOT_WAIT_TIME 15 /* default to 15 seconds */
    #endif
    static int panic_reboot_wait_time = PANIC_REBOOT_WAIT_TIME;
    SYSCTL_INT(_kern, OID_AUTO, panic_reboot_wait_time, CTLFLAG_RWTUN,
        &panic_reboot_wait_time, 0,
        "Seconds to wait before rebooting after a panic");
   
   /*
    * Note that stdarg.h and the ANSI style va_start macro is used for both
    * ANSI and traditional C compilers.
    */
   #include <machine/stdarg.h>
   
   #ifdef KDB
   #ifdef KDB_UNATTENDED
   int debugger_on_panic = 0;
   #else
   int debugger_on_panic = 1;
   #endif
   SYSCTL_INT(_debug, OID_AUTO, debugger_on_panic,
       CTLFLAG_RWTUN | CTLFLAG_SECURE,
       &debugger_on_panic, 0, "Run debugger on kernel panic");
   
   #ifdef KDB_TRACE
   static int trace_on_panic = 1;
   #else
   static int trace_on_panic = 0;
   #endif
   SYSCTL_INT(_debug, OID_AUTO, trace_on_panic,
       CTLFLAG_RWTUN | CTLFLAG_SECURE,
       &trace_on_panic, 0, "Print stack trace on kernel panic");
   #endif /* KDB */
   
   static int sync_on_panic = 0;
   SYSCTL_INT(_kern, OID_AUTO, sync_on_panic, CTLFLAG_RWTUN,
           &sync_on_panic, 0, "Do a sync before rebooting from a panic");
   
   static SYSCTL_NODE(_kern, OID_AUTO, shutdown, CTLFLAG_RW, 0,
       "Shutdown environment");
   
   #ifndef DIAGNOSTIC
   static int show_busybufs;
   #else
   static int show_busybufs = 1;
   #endif
   SYSCTL_INT(_kern_shutdown, OID_AUTO, show_busybufs, CTLFLAG_RW,
           &show_busybufs, 0, "");
   
   int suspend_blocked = 0;
   SYSCTL_INT(_kern, OID_AUTO, suspend_blocked, CTLFLAG_RW,
           &suspend_blocked, 0, "Block suspend due to a pending shutdown");
   
   /*
    * Variable panicstr contains argument to first call to panic; used as flag
    * to indicate that the kernel has already called panic.
    */
   const char *panicstr;
   
   int dumping;                            /* system is dumping */
   int rebooting;                          /* system is rebooting */
   static struct dumperinfo dumper;        /* our selected dumper */
   
   /* Context information for dump-debuggers. */
   static struct pcb dumppcb;              /* Registers. */
   lwpid_t dumptid;                        /* Thread ID. */
   
   static struct cdevsw reroot_cdevsw = {
        .d_version = D_VERSION,
        .d_name    = "reroot",
   };
   
   static void poweroff_wait(void *, int);
   static void shutdown_halt(void *junk, int howto);
   static void shutdown_panic(void *junk, int howto);
   static void shutdown_reset(void *junk, int howto);
   static int kern_reroot(void);
   
   /* register various local shutdown events */
   static void
   shutdown_conf(void *unused)
   {
   
           EVENTHANDLER_REGISTER(shutdown_final, poweroff_wait, NULL,
               SHUTDOWN_PRI_FIRST);
           EVENTHANDLER_REGISTER(shutdown_final, shutdown_halt, NULL,
               SHUTDOWN_PRI_LAST + 100);
           EVENTHANDLER_REGISTER(shutdown_final, shutdown_panic, NULL,
               SHUTDOWN_PRI_LAST + 100);
           EVENTHANDLER_REGISTER(shutdown_final, shutdown_reset, NULL,
               SHUTDOWN_PRI_LAST + 200);
   }
   
   SYSINIT(shutdown_conf, SI_SUB_INTRINSIC, SI_ORDER_ANY, shutdown_conf, NULL);
   
   /*
    * The only reason this exists is to create the /dev/reroot/ directory,
    * used by reroot code in init(8) as a mountpoint for tmpfs.
    */
   static void
   reroot_conf(void *unused)
   {
           int error;
           struct cdev *cdev;
   
           error = make_dev_p(MAKEDEV_CHECKNAME | MAKEDEV_WAITOK, &cdev,
               &reroot_cdevsw, NULL, UID_ROOT, GID_WHEEL, 0600, "reroot/reroot");
           if (error != 0) {
                   printf("%s: failed to create device node, error %d",
                       __func__, error);
           }
   }
   
   SYSINIT(reroot_conf, SI_SUB_DEVFS, SI_ORDER_ANY, reroot_conf, NULL);
   
   /*
    * The system call that results in a reboot.
    */
   /* ARGSUSED */
   int
   sys_reboot(struct thread *td, struct reboot_args *uap)
   {
           int error;
   
           error = 0;
   #ifdef MAC
           error = mac_system_check_reboot(td->td_ucred, uap->opt);
   #endif
           if (error == 0)
                   error = priv_check(td, PRIV_REBOOT);
           if (error == 0) {
                   if (uap->opt & RB_REROOT) {
                           error = kern_reroot();
                   } else {
                           mtx_lock(&Giant);
                           kern_reboot(uap->opt);
                           mtx_unlock(&Giant);
                   }
           }
           return (error);
   }
   
   /*
    * Called by events that want to shut down.. e.g  <CTL><ALT><DEL> on a PC
    */
   void
   shutdown_nice(int howto)
   {
   
           if (initproc != NULL) {
                   /* Send a signal to init(8) and have it shutdown the world. */
                   PROC_LOCK(initproc);
                   if (howto & RB_POWEROFF)
                           kern_psignal(initproc, SIGUSR2);
                   else if (howto & RB_HALT)
                           kern_psignal(initproc, SIGUSR1);
                   else
                           kern_psignal(initproc, SIGINT);
                   PROC_UNLOCK(initproc);
           } else {
                   /* No init(8) running, so simply reboot. */
                   kern_reboot(howto | RB_NOSYNC);
           }
   }
   
   static void
   print_uptime(void)
   {
           int f;
           struct timespec ts;
   
           getnanouptime(&ts);
           printf("Uptime: ");
           f = 0;
           if (ts.tv_sec >= 86400) {
                   printf("%ldd", (long)ts.tv_sec / 86400);
                   ts.tv_sec %= 86400;
                   f = 1;
           }
           if (f || ts.tv_sec >= 3600) {
                   printf("%ldh", (long)ts.tv_sec / 3600);
                   ts.tv_sec %= 3600;
                   f = 1;
           }
           if (f || ts.tv_sec >= 60) {
                   printf("%ldm", (long)ts.tv_sec / 60);
                   ts.tv_sec %= 60;
                   f = 1;
           }
           printf("%lds\n", (long)ts.tv_sec);
   }
   
   int
   doadump(boolean_t textdump)
   {
           boolean_t coredump;
           int error;
   
           error = 0;
           if (dumping)
                   return (EBUSY);
           if (dumper.dumper == NULL)
                   return (ENXIO);
   
           savectx(&dumppcb);
           dumptid = curthread->td_tid;
           dumping++;
   
           coredump = TRUE;
   #ifdef DDB
           if (textdump && textdump_pending) {
                   coredump = FALSE;
                   textdump_dumpsys(&dumper);
           }
   #endif
           if (coredump)
                   error = dumpsys(&dumper);
   
           dumping--;
           return (error);
   }
   
   /*
    * Shutdown the system cleanly to prepare for reboot, halt, or power off.
    */
   void
   kern_reboot(int howto)
   {
           static int once = 0;
   
   #if defined(SMP)
           /*
            * Bind us to CPU 0 so that all shutdown code runs there.  Some
            * systems don't shutdown properly (i.e., ACPI power off) if we
            * run on another processor.
            */
           if (!SCHEDULER_STOPPED()) {
                   thread_lock(curthread);
                   sched_bind(curthread, 0);
                   thread_unlock(curthread);
                   KASSERT(PCPU_GET(cpuid) == 0, ("boot: not running on cpu 0"));
           }
   #endif
           /* We're in the process of rebooting. */
           rebooting = 1;
   
           /* We are out of the debugger now. */
           kdb_active = 0;
   
           /*
            * Do any callouts that should be done BEFORE syncing the filesystems.
            */
           EVENTHANDLER_INVOKE(shutdown_pre_sync, howto);
   
           /* 
            * Now sync filesystems
            */
           if (!cold && (howto & RB_NOSYNC) == 0 && once == 0) {
                   once = 1;
                   bufshutdown(show_busybufs);
           }
   
           print_uptime();
   
           cngrab();
   
           /*
            * Ok, now do things that assume all filesystem activity has
            * been completed.
            */
           EVENTHANDLER_INVOKE(shutdown_post_sync, howto);
   
           if ((howto & (RB_HALT|RB_DUMP)) == RB_DUMP && !cold && !dumping) 
                   doadump(TRUE);
   
           /* Now that we're going to really halt the system... */
           EVENTHANDLER_INVOKE(shutdown_final, howto);
   
           for(;;) ;       /* safety against shutdown_reset not working */
           /* NOTREACHED */
   }
   
   /*
    * The system call that results in changing the rootfs.
    */
   static int
   kern_reroot(void)
   {
           struct vnode *oldrootvnode, *vp;
           struct mount *mp, *devmp;
           int error;
   
           if (curproc != initproc)
                   return (EPERM);
   
           /*
            * Mark the filesystem containing currently-running executable
            * (the temporary copy of init(8)) busy.
            */
           vp = curproc->p_textvp;
           error = vn_lock(vp, LK_SHARED);
           if (error != 0)
                   return (error);
           mp = vp->v_mount;
           error = vfs_busy(mp, MBF_NOWAIT);
           if (error != 0) {
                   vfs_ref(mp);
                   VOP_UNLOCK(vp, 0);
                   error = vfs_busy(mp, 0);
                   vn_lock(vp, LK_SHARED | LK_RETRY);
                   vfs_rel(mp);
                   if (error != 0) {
                           VOP_UNLOCK(vp, 0);
                           return (ENOENT);
                   }
                   if (vp->v_iflag & VI_DOOMED) {
                           VOP_UNLOCK(vp, 0);
                           vfs_unbusy(mp);
                           return (ENOENT);
                   }
           }
           VOP_UNLOCK(vp, 0);
   
           /*
            * Remove the filesystem containing currently-running executable
            * from the mount list, to prevent it from being unmounted
            * by vfs_unmountall(), and to avoid confusing vfs_mountroot().
            *
            * Also preserve /dev - forcibly unmounting it could cause driver
            * reinitialization.
            */
   
           vfs_ref(rootdevmp);
           devmp = rootdevmp;
           rootdevmp = NULL;
   
           mtx_lock(&mountlist_mtx);
           TAILQ_REMOVE(&mountlist, mp, mnt_list);
           TAILQ_REMOVE(&mountlist, devmp, mnt_list);
           mtx_unlock(&mountlist_mtx);
   
           oldrootvnode = rootvnode;
   
           /*
            * Unmount everything except for the two filesystems preserved above.
            */
           vfs_unmountall();
   
           /*
            * Add /dev back; vfs_mountroot() will move it into its new place.
            */
           mtx_lock(&mountlist_mtx);
           TAILQ_INSERT_HEAD(&mountlist, devmp, mnt_list);
           mtx_unlock(&mountlist_mtx);
           rootdevmp = devmp;
           vfs_rel(rootdevmp);
   
           /*
            * Mount the new rootfs.
            */
           vfs_mountroot();
   
           /*
            * Update all references to the old rootvnode.
            */
           mountcheckdirs(oldrootvnode, rootvnode);
   
           /*
            * Add the temporary filesystem back and unbusy it.
            */
           mtx_lock(&mountlist_mtx);
           TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
           mtx_unlock(&mountlist_mtx);
           vfs_unbusy(mp);
   
           return (0);
   }
   
   /*
    * If the shutdown was a clean halt, behave accordingly.
    */
   static void
   shutdown_halt(void *junk, int howto)
   {
   
           if (howto & RB_HALT) {
                   printf("\n");
                   printf("The operating system has halted.\n");
                   printf("Please press any key to reboot.\n\n");
                   switch (cngetc()) {
                   case -1:                /* No console, just die */
                           cpu_halt();
                           /* NOTREACHED */
                   default:
                           howto &= ~RB_HALT;
                           break;
                   }
           }
   }
   
   /*
    * Check to see if the system paniced, pause and then reboot
    * according to the specified delay.
    */
   static void
   shutdown_panic(void *junk, int howto)
   {
           int loop;
   
           if (howto & RB_DUMP) {
                   if (panic_reboot_wait_time != 0) {
                           if (panic_reboot_wait_time != -1) {
                                   printf("Automatic reboot in %d seconds - "
                                          "press a key on the console to abort\n",
                                           panic_reboot_wait_time);
                                   for (loop = panic_reboot_wait_time * 10;
                                        loop > 0; --loop) {
                                           DELAY(1000 * 100); /* 1/10th second */
                                           /* Did user type a key? */
                                           if (cncheckc() != -1)
                                                   break;
                                   }
                                   if (!loop)
                                           return;
                           }
                   } else { /* zero time specified - reboot NOW */
                           return;
                   }
                   printf("--> Press a key on the console to reboot,\n");
                   printf("--> or switch off the system now.\n");
                   cngetc();
           }
   }
   
   /*
    * Everything done, now reset
    */
   static void
   shutdown_reset(void *junk, int howto)
   {
   
           printf("Rebooting...\n");
           DELAY(1000000); /* wait 1 sec for printf's to complete and be read */
   
           /*
            * Acquiring smp_ipi_mtx here has a double effect:
            * - it disables interrupts avoiding CPU0 preemption
            *   by fast handlers (thus deadlocking  against other CPUs)
            * - it avoids deadlocks against smp_rendezvous() or, more 
            *   generally, threads busy-waiting, with this spinlock held,
            *   and waiting for responses by threads on other CPUs
            *   (ie. smp_tlb_shootdown()).
            *
            * For the !SMP case it just needs to handle the former problem.
            */
   #ifdef SMP
           mtx_lock_spin(&smp_ipi_mtx);
   #else
           spinlock_enter();
   #endif
   
           /* cpu_boot(howto); */ /* doesn't do anything at the moment */
           cpu_reset();
           /* NOTREACHED */ /* assuming reset worked */
   }
   
   #if defined(WITNESS) || defined(INVARIANT_SUPPORT)
   static int kassert_warn_only = 0;
   #ifdef KDB
   static int kassert_do_kdb = 0;
   #endif
   #ifdef KTR
   static int kassert_do_ktr = 0;
   #endif
   static int kassert_do_log = 1;
   static int kassert_log_pps_limit = 4;
   static int kassert_log_mute_at = 0;
   static int kassert_log_panic_at = 0;
   static int kassert_warnings = 0;
   
   SYSCTL_NODE(_debug, OID_AUTO, kassert, CTLFLAG_RW, NULL, "kassert options");
   
   SYSCTL_INT(_debug_kassert, OID_AUTO, warn_only, CTLFLAG_RWTUN,
       &kassert_warn_only, 0,
       "KASSERT triggers a panic (1) or just a warning (0)");
   
   #ifdef KDB
   SYSCTL_INT(_debug_kassert, OID_AUTO, do_kdb, CTLFLAG_RWTUN,
       &kassert_do_kdb, 0, "KASSERT will enter the debugger");
   #endif
   
   #ifdef KTR
   SYSCTL_UINT(_debug_kassert, OID_AUTO, do_ktr, CTLFLAG_RWTUN,
       &kassert_do_ktr, 0,
       "KASSERT does a KTR, set this to the KTRMASK you want");
   #endif
   
   SYSCTL_INT(_debug_kassert, OID_AUTO, do_log, CTLFLAG_RWTUN,
       &kassert_do_log, 0, "KASSERT triggers a panic (1) or just a warning (0)");
   
   SYSCTL_INT(_debug_kassert, OID_AUTO, warnings, CTLFLAG_RWTUN,
       &kassert_warnings, 0, "number of KASSERTs that have been triggered");
   
   SYSCTL_INT(_debug_kassert, OID_AUTO, log_panic_at, CTLFLAG_RWTUN,
       &kassert_log_panic_at, 0, "max number of KASSERTS before we will panic");
   
   SYSCTL_INT(_debug_kassert, OID_AUTO, log_pps_limit, CTLFLAG_RWTUN,
       &kassert_log_pps_limit, 0, "limit number of log messages per second");
   
   SYSCTL_INT(_debug_kassert, OID_AUTO, log_mute_at, CTLFLAG_RWTUN,
       &kassert_log_mute_at, 0, "max number of KASSERTS to log");
   
   static int kassert_sysctl_kassert(SYSCTL_HANDLER_ARGS);
   
   SYSCTL_PROC(_debug_kassert, OID_AUTO, kassert,
       CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
       kassert_sysctl_kassert, "I", "set to trigger a test kassert");
   
   static int
   kassert_sysctl_kassert(SYSCTL_HANDLER_ARGS)
   {
           int error, i;
   
           error = sysctl_wire_old_buffer(req, sizeof(int));
           if (error == 0) {
                   i = 0;
                   error = sysctl_handle_int(oidp, &i, 0, req);
           }
           if (error != 0 || req->newptr == NULL)
                   return (error);
           KASSERT(0, ("kassert_sysctl_kassert triggered kassert %d", i));
           return (0);
   }
   
   /*
    * Called by KASSERT, this decides if we will panic
    * or if we will log via printf and/or ktr.
    */
   void
   kassert_panic(const char *fmt, ...)
   {
           static char buf[256];
           va_list ap;
   
           va_start(ap, fmt);
           (void)vsnprintf(buf, sizeof(buf), fmt, ap);
           va_end(ap);
   
           /*
            * panic if we're not just warning, or if we've exceeded
            * kassert_log_panic_at warnings.
            */
           if (!kassert_warn_only ||
               (kassert_log_panic_at > 0 &&
                kassert_warnings >= kassert_log_panic_at)) {
                   va_start(ap, fmt);
                   vpanic(fmt, ap);
                   /* NORETURN */
           }
   #ifdef KTR
           if (kassert_do_ktr)
                   CTR0(ktr_mask, buf);
   #endif /* KTR */
           /*
            * log if we've not yet met the mute limit.
            */
           if (kassert_do_log &&
               (kassert_log_mute_at == 0 ||
                kassert_warnings < kassert_log_mute_at)) {
                   static  struct timeval lasterr;
                   static  int curerr;
   
                   if (ppsratecheck(&lasterr, &curerr, kassert_log_pps_limit)) {
                           printf("KASSERT failed: %s\n", buf);
                           kdb_backtrace();
                   }
           }
   #ifdef KDB
           if (kassert_do_kdb) {
                   kdb_enter(KDB_WHY_KASSERT, buf);
           }
   #endif
           atomic_add_int(&kassert_warnings, 1);
   }
   #endif
   
   /*
    * Panic is called on unresolvable fatal errors.  It prints "panic: mesg",
    * and then reboots.  If we are called twice, then we avoid trying to sync
    * the disks as this often leads to recursive panics.
    */
   void
   panic(const char *fmt, ...)
   {
           va_list ap;
   
           va_start(ap, fmt);
           vpanic(fmt, ap);
   }
   
   void
   vpanic(const char *fmt, va_list ap)
   {
   #ifdef SMP
           cpuset_t other_cpus;
   #endif
           struct thread *td = curthread;
           int bootopt, newpanic;
           static char buf[256];
   
           spinlock_enter();
   
   #ifdef SMP
           /*
            * stop_cpus_hard(other_cpus) should prevent multiple CPUs from
            * concurrently entering panic.  Only the winner will proceed
            * further.
            */
           if (panicstr == NULL && !kdb_active) {
                   other_cpus = all_cpus;
                   CPU_CLR(PCPU_GET(cpuid), &other_cpus);
                   stop_cpus_hard(other_cpus);
           }
   #endif
   
           /*
            * Ensure that the scheduler is stopped while panicking, even if panic
            * has been entered from kdb.
            */
           td->td_stopsched = 1;
   
           bootopt = RB_AUTOBOOT;
           newpanic = 0;
           if (panicstr)
                   bootopt |= RB_NOSYNC;
           else {
                   bootopt |= RB_DUMP;
                   panicstr = fmt;
                   newpanic = 1;
           }
   
           if (newpanic) {
                   (void)vsnprintf(buf, sizeof(buf), fmt, ap);
                   panicstr = buf;
                   cngrab();
                   printf("panic: %s\n", buf);
           } else {
                   printf("panic: ");
                   vprintf(fmt, ap);
                   printf("\n");
           }
   #ifdef SMP
           printf("cpuid = %d\n", PCPU_GET(cpuid));
   #endif
   
   #ifdef KDB
           if (newpanic && trace_on_panic)
                   kdb_backtrace();
           if (debugger_on_panic)
                   kdb_enter(KDB_WHY_PANIC, "panic");
   #endif
           /*thread_lock(td); */
           td->td_flags |= TDF_INPANIC;
           /* thread_unlock(td); */
           if (!sync_on_panic)
                   bootopt |= RB_NOSYNC;
           kern_reboot(bootopt);
   }
   
   /*
    * Support for poweroff delay.
    *
    * Please note that setting this delay too short might power off your machine
    * before the write cache on your hard disk has been flushed, leading to
    * soft-updates inconsistencies.
    */
   #ifndef POWEROFF_DELAY
   # define POWEROFF_DELAY 5000
   #endif
   static int poweroff_delay = POWEROFF_DELAY;
   
   SYSCTL_INT(_kern_shutdown, OID_AUTO, poweroff_delay, CTLFLAG_RW,
       &poweroff_delay, 0, "Delay before poweroff to write disk caches (msec)");
   
   static void
   poweroff_wait(void *junk, int howto)
   {
   
           if (!(howto & RB_POWEROFF) || poweroff_delay <= 0)
                   return;
           DELAY(poweroff_delay * 1000);
   }
   
   /*
    * Some system processes (e.g. syncer) need to be stopped at appropriate
    * points in their main loops prior to a system shutdown, so that they
    * won't interfere with the shutdown process (e.g. by holding a disk buf
    * to cause sync to fail).  For each of these system processes, register
    * shutdown_kproc() as a handler for one of shutdown events.
    */
   static int kproc_shutdown_wait = 60;
   SYSCTL_INT(_kern_shutdown, OID_AUTO, kproc_shutdown_wait, CTLFLAG_RW,
       &kproc_shutdown_wait, 0, "Max wait time (sec) to stop for each process");
   
   void
   kproc_shutdown(void *arg, int howto)
   {
           struct proc *p;
           int error;
   
           if (panicstr)
                   return;
   
           p = (struct proc *)arg;
           printf("Waiting (max %d seconds) for system process `%s' to stop... ",
               kproc_shutdown_wait, p->p_comm);
           error = kproc_suspend(p, kproc_shutdown_wait * hz);
   
           if (error == EWOULDBLOCK)
                   printf("timed out\n");
           else
                   printf("done\n");
   }
   
   void
   kthread_shutdown(void *arg, int howto)
   {
           struct thread *td;
           int error;
   
           if (panicstr)
                   return;
   
           td = (struct thread *)arg;
           printf("Waiting (max %d seconds) for system thread `%s' to stop... ",
               kproc_shutdown_wait, td->td_name);
           error = kthread_suspend(td, kproc_shutdown_wait * hz);
   
           if (error == EWOULDBLOCK)
                   printf("timed out\n");
           else
                   printf("done\n");
   }
   
   static char dumpdevname[sizeof(((struct cdev*)NULL)->si_name)];
   SYSCTL_STRING(_kern_shutdown, OID_AUTO, dumpdevname, CTLFLAG_RD,
       dumpdevname, 0, "Device for kernel dumps");
   
   /* Registration of dumpers */
   int
   set_dumper(struct dumperinfo *di, const char *devname, struct thread *td)
   {
           size_t wantcopy;
           int error;
   
           error = priv_check(td, PRIV_SETDUMPER);
           if (error != 0)
                   return (error);
   
           if (di == NULL) {
                   if (dumper.blockbuf != NULL)
                           free(dumper.blockbuf, M_DUMPER);
                   bzero(&dumper, sizeof(dumper));
                   dumpdevname[0] = '\0';
                   return (0);
           }
           if (dumper.dumper != NULL)
                   return (EBUSY);
           dumper = *di;
           wantcopy = strlcpy(dumpdevname, devname, sizeof(dumpdevname));
           if (wantcopy >= sizeof(dumpdevname)) {
                   printf("set_dumper: device name truncated from '%s' -> '%s'\n",
                           devname, dumpdevname);
           }
           dumper.blockbuf = malloc(di->blocksize, M_DUMPER, M_WAITOK | M_ZERO);
           return (0);
   }
   
   /* Call dumper with bounds checking. */
   int
   dump_write(struct dumperinfo *di, void *virtual, vm_offset_t physical,
       off_t offset, size_t length)
   {
   
           if (length != 0 && (offset < di->mediaoffset ||
               offset - di->mediaoffset + length > di->mediasize)) {
                   printf("Attempt to write outside dump device boundaries.\n"
               "offset(%jd), mediaoffset(%jd), length(%ju), mediasize(%jd).\n",
                       (intmax_t)offset, (intmax_t)di->mediaoffset,
                       (uintmax_t)length, (intmax_t)di->mediasize);
                   return (ENOSPC);
           }
           return (di->dumper(di->priv, virtual, physical, offset, length));
   }
   
   /* Call dumper with bounds checking. */
   int
   dump_write_pad(struct dumperinfo *di, void *virtual, vm_offset_t physical,
       off_t offset, size_t length, size_t *size)
   {
           char *temp;
           int ret;
   
           if (length > di->blocksize)
                   return (ENOMEM);
   
           *size = di->blocksize;
           if (length == di->blocksize)
                   temp = virtual;
           else {
                   temp = di->blockbuf;
                   memset(temp + length, 0, di->blocksize - length);
                   memcpy(temp, virtual, length);
           }
           ret = dump_write(di, temp, physical, offset, *size);
   
           return (ret);
   }
   
   
   void
   mkdumpheader(struct kerneldumpheader *kdh, char *magic, uint32_t archver,
       uint64_t dumplen, uint32_t blksz)
   {
   
           bzero(kdh, sizeof(*kdh));
           strlcpy(kdh->magic, magic, sizeof(kdh->magic));
           strlcpy(kdh->architecture, MACHINE_ARCH, sizeof(kdh->architecture));
           kdh->version = htod32(KERNELDUMPVERSION);
           kdh->architectureversion = htod32(archver);
           kdh->dumplength = htod64(dumplen);
           kdh->dumptime = htod64(time_second);
           kdh->blocksize = htod32(blksz);
           strlcpy(kdh->hostname, prison0.pr_hostname, sizeof(kdh->hostname));
           strlcpy(kdh->versionstring, version, sizeof(kdh->versionstring));
           if (panicstr != NULL)
                   strlcpy(kdh->panicstring, panicstr, sizeof(kdh->panicstring));
           kdh->parity = kerneldump_parity(kdh);
   }
   
   #ifdef DDB
   DB_SHOW_COMMAND(panic, db_show_panic)
   {
   
           if (panicstr == NULL)
                   db_printf("panicstr not set\n");
           else
                   db_printf("panic: %s\n", panicstr);
   }
   #endif

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