The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 1986, 1988, 1991, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  * (c) UNIX System Laboratories, Inc.
    5  * All or some portions of this file are derived from material licensed
    6  * to the University of California by American Telephone and Telegraph
    7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    8  * the permission of UNIX System Laboratories, Inc.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)kern_shutdown.c     8.3 (Berkeley) 1/21/94
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD: releng/11.2/sys/kern/kern_shutdown.c 331736 2018-03-29 15:12:03Z kib $");
   39 
   40 #include "opt_ddb.h"
   41 #include "opt_kdb.h"
   42 #include "opt_panic.h"
   43 #include "opt_sched.h"
   44 #include "opt_watchdog.h"
   45 
   46 #include <sys/param.h>
   47 #include <sys/systm.h>
   48 #include <sys/bio.h>
   49 #include <sys/buf.h>
   50 #include <sys/conf.h>
   51 #include <sys/cons.h>
   52 #include <sys/eventhandler.h>
   53 #include <sys/filedesc.h>
   54 #include <sys/jail.h>
   55 #include <sys/kdb.h>
   56 #include <sys/kernel.h>
   57 #include <sys/kerneldump.h>
   58 #include <sys/kthread.h>
   59 #include <sys/ktr.h>
   60 #include <sys/malloc.h>
   61 #include <sys/mount.h>
   62 #include <sys/priv.h>
   63 #include <sys/proc.h>
   64 #include <sys/reboot.h>
   65 #include <sys/resourcevar.h>
   66 #include <sys/rwlock.h>
   67 #include <sys/sched.h>
   68 #include <sys/smp.h>
   69 #include <sys/sysctl.h>
   70 #include <sys/sysproto.h>
   71 #include <sys/taskqueue.h>
   72 #include <sys/vnode.h>
   73 #include <sys/watchdog.h>
   74 
   75 #include <ddb/ddb.h>
   76 
   77 #include <machine/cpu.h>
   78 #include <machine/dump.h>
   79 #include <machine/pcb.h>
   80 #include <machine/smp.h>
   81 
   82 #include <security/mac/mac_framework.h>
   83 
   84 #include <vm/vm.h>
   85 #include <vm/vm_object.h>
   86 #include <vm/vm_page.h>
   87 #include <vm/vm_pager.h>
   88 #include <vm/swap_pager.h>
   89 
   90 #include <sys/signalvar.h>
   91 
   92 static MALLOC_DEFINE(M_DUMPER, "dumper", "dumper block buffer");
   93 
   94 #ifndef PANIC_REBOOT_WAIT_TIME
   95 #define PANIC_REBOOT_WAIT_TIME 15 /* default to 15 seconds */
   96 #endif
   97 static int panic_reboot_wait_time = PANIC_REBOOT_WAIT_TIME;
   98 SYSCTL_INT(_kern, OID_AUTO, panic_reboot_wait_time, CTLFLAG_RWTUN,
   99     &panic_reboot_wait_time, 0,
  100     "Seconds to wait before rebooting after a panic");
  101 
  102 /*
  103  * Note that stdarg.h and the ANSI style va_start macro is used for both
  104  * ANSI and traditional C compilers.
  105  */
  106 #include <machine/stdarg.h>
  107 
  108 #ifdef KDB
  109 #ifdef KDB_UNATTENDED
  110 int debugger_on_panic = 0;
  111 #else
  112 int debugger_on_panic = 1;
  113 #endif
  114 SYSCTL_INT(_debug, OID_AUTO, debugger_on_panic,
  115     CTLFLAG_RWTUN | CTLFLAG_SECURE,
  116     &debugger_on_panic, 0, "Run debugger on kernel panic");
  117 
  118 #ifdef KDB_TRACE
  119 static int trace_on_panic = 1;
  120 #else
  121 static int trace_on_panic = 0;
  122 #endif
  123 SYSCTL_INT(_debug, OID_AUTO, trace_on_panic,
  124     CTLFLAG_RWTUN | CTLFLAG_SECURE,
  125     &trace_on_panic, 0, "Print stack trace on kernel panic");
  126 #endif /* KDB */
  127 
  128 static int sync_on_panic = 0;
  129 SYSCTL_INT(_kern, OID_AUTO, sync_on_panic, CTLFLAG_RWTUN,
  130         &sync_on_panic, 0, "Do a sync before rebooting from a panic");
  131 
  132 static SYSCTL_NODE(_kern, OID_AUTO, shutdown, CTLFLAG_RW, 0,
  133     "Shutdown environment");
  134 
  135 #ifndef DIAGNOSTIC
  136 static int show_busybufs;
  137 #else
  138 static int show_busybufs = 1;
  139 #endif
  140 SYSCTL_INT(_kern_shutdown, OID_AUTO, show_busybufs, CTLFLAG_RW,
  141         &show_busybufs, 0, "");
  142 
  143 int suspend_blocked = 0;
  144 SYSCTL_INT(_kern, OID_AUTO, suspend_blocked, CTLFLAG_RW,
  145         &suspend_blocked, 0, "Block suspend due to a pending shutdown");
  146 
  147 /*
  148  * Variable panicstr contains argument to first call to panic; used as flag
  149  * to indicate that the kernel has already called panic.
  150  */
  151 const char *panicstr;
  152 
  153 int dumping;                            /* system is dumping */
  154 int rebooting;                          /* system is rebooting */
  155 static struct dumperinfo dumper;        /* our selected dumper */
  156 
  157 /* Context information for dump-debuggers. */
  158 static struct pcb dumppcb;              /* Registers. */
  159 lwpid_t dumptid;                        /* Thread ID. */
  160 
  161 static struct cdevsw reroot_cdevsw = {
  162      .d_version = D_VERSION,
  163      .d_name    = "reroot",
  164 };
  165 
  166 static void poweroff_wait(void *, int);
  167 static void shutdown_halt(void *junk, int howto);
  168 static void shutdown_panic(void *junk, int howto);
  169 static void shutdown_reset(void *junk, int howto);
  170 static int kern_reroot(void);
  171 
  172 /* register various local shutdown events */
  173 static void
  174 shutdown_conf(void *unused)
  175 {
  176 
  177         EVENTHANDLER_REGISTER(shutdown_final, poweroff_wait, NULL,
  178             SHUTDOWN_PRI_FIRST);
  179         EVENTHANDLER_REGISTER(shutdown_final, shutdown_halt, NULL,
  180             SHUTDOWN_PRI_LAST + 100);
  181         EVENTHANDLER_REGISTER(shutdown_final, shutdown_panic, NULL,
  182             SHUTDOWN_PRI_LAST + 100);
  183         EVENTHANDLER_REGISTER(shutdown_final, shutdown_reset, NULL,
  184             SHUTDOWN_PRI_LAST + 200);
  185 }
  186 
  187 SYSINIT(shutdown_conf, SI_SUB_INTRINSIC, SI_ORDER_ANY, shutdown_conf, NULL);
  188 
  189 /*
  190  * The only reason this exists is to create the /dev/reroot/ directory,
  191  * used by reroot code in init(8) as a mountpoint for tmpfs.
  192  */
  193 static void
  194 reroot_conf(void *unused)
  195 {
  196         int error;
  197         struct cdev *cdev;
  198 
  199         error = make_dev_p(MAKEDEV_CHECKNAME | MAKEDEV_WAITOK, &cdev,
  200             &reroot_cdevsw, NULL, UID_ROOT, GID_WHEEL, 0600, "reroot/reroot");
  201         if (error != 0) {
  202                 printf("%s: failed to create device node, error %d",
  203                     __func__, error);
  204         }
  205 }
  206 
  207 SYSINIT(reroot_conf, SI_SUB_DEVFS, SI_ORDER_ANY, reroot_conf, NULL);
  208 
  209 /*
  210  * The system call that results in a reboot.
  211  */
  212 /* ARGSUSED */
  213 int
  214 sys_reboot(struct thread *td, struct reboot_args *uap)
  215 {
  216         int error;
  217 
  218         error = 0;
  219 #ifdef MAC
  220         error = mac_system_check_reboot(td->td_ucred, uap->opt);
  221 #endif
  222         if (error == 0)
  223                 error = priv_check(td, PRIV_REBOOT);
  224         if (error == 0) {
  225                 if (uap->opt & RB_REROOT) {
  226                         error = kern_reroot();
  227                 } else {
  228                         mtx_lock(&Giant);
  229                         kern_reboot(uap->opt);
  230                         mtx_unlock(&Giant);
  231                 }
  232         }
  233         return (error);
  234 }
  235 
  236 static void
  237 shutdown_nice_task_fn(void *arg, int pending __unused)
  238 {
  239         int howto;
  240 
  241         howto = (uintptr_t)arg;
  242         /* Send a signal to init(8) and have it shutdown the world. */
  243         PROC_LOCK(initproc);
  244         if (howto & RB_POWEROFF)
  245                 kern_psignal(initproc, SIGUSR2);
  246         else if (howto & RB_HALT)
  247                 kern_psignal(initproc, SIGUSR1);
  248         else
  249                 kern_psignal(initproc, SIGINT);
  250         PROC_UNLOCK(initproc);
  251 }
  252 
  253 static struct task shutdown_nice_task = TASK_INITIALIZER(0,
  254     &shutdown_nice_task_fn, NULL);
  255 
  256 /*
  257  * Called by events that want to shut down.. e.g  <CTL><ALT><DEL> on a PC
  258  */
  259 void
  260 shutdown_nice(int howto)
  261 {
  262 
  263         if (initproc != NULL && !SCHEDULER_STOPPED()) {
  264                 shutdown_nice_task.ta_context = (void *)(uintptr_t)howto;
  265                 taskqueue_enqueue(taskqueue_fast, &shutdown_nice_task);
  266         } else {
  267                 /*
  268                  * No init(8) running, or scheduler would not allow it
  269                  * to run, so simply reboot.
  270                  */
  271                 kern_reboot(howto | RB_NOSYNC);
  272         }
  273 }
  274 
  275 static void
  276 print_uptime(void)
  277 {
  278         int f;
  279         struct timespec ts;
  280 
  281         getnanouptime(&ts);
  282         printf("Uptime: ");
  283         f = 0;
  284         if (ts.tv_sec >= 86400) {
  285                 printf("%ldd", (long)ts.tv_sec / 86400);
  286                 ts.tv_sec %= 86400;
  287                 f = 1;
  288         }
  289         if (f || ts.tv_sec >= 3600) {
  290                 printf("%ldh", (long)ts.tv_sec / 3600);
  291                 ts.tv_sec %= 3600;
  292                 f = 1;
  293         }
  294         if (f || ts.tv_sec >= 60) {
  295                 printf("%ldm", (long)ts.tv_sec / 60);
  296                 ts.tv_sec %= 60;
  297                 f = 1;
  298         }
  299         printf("%lds\n", (long)ts.tv_sec);
  300 }
  301 
  302 int
  303 doadump(boolean_t textdump)
  304 {
  305         boolean_t coredump;
  306         int error;
  307 
  308         error = 0;
  309         if (dumping)
  310                 return (EBUSY);
  311         if (dumper.dumper == NULL)
  312                 return (ENXIO);
  313 
  314         savectx(&dumppcb);
  315         dumptid = curthread->td_tid;
  316         dumping++;
  317 
  318         coredump = TRUE;
  319 #ifdef DDB
  320         if (textdump && textdump_pending) {
  321                 coredump = FALSE;
  322                 textdump_dumpsys(&dumper);
  323         }
  324 #endif
  325         if (coredump)
  326                 error = dumpsys(&dumper);
  327 
  328         dumping--;
  329         return (error);
  330 }
  331 
  332 /*
  333  * Shutdown the system cleanly to prepare for reboot, halt, or power off.
  334  */
  335 void
  336 kern_reboot(int howto)
  337 {
  338         static int once = 0;
  339 
  340 #if defined(SMP)
  341         /*
  342          * Bind us to CPU 0 so that all shutdown code runs there.  Some
  343          * systems don't shutdown properly (i.e., ACPI power off) if we
  344          * run on another processor.
  345          */
  346         if (!SCHEDULER_STOPPED()) {
  347                 thread_lock(curthread);
  348                 sched_bind(curthread, 0);
  349                 thread_unlock(curthread);
  350                 KASSERT(PCPU_GET(cpuid) == 0, ("boot: not running on cpu 0"));
  351         }
  352 #endif
  353         /* We're in the process of rebooting. */
  354         rebooting = 1;
  355 
  356         /* We are out of the debugger now. */
  357         kdb_active = 0;
  358 
  359         /*
  360          * Do any callouts that should be done BEFORE syncing the filesystems.
  361          */
  362         EVENTHANDLER_INVOKE(shutdown_pre_sync, howto);
  363 
  364         /* 
  365          * Now sync filesystems
  366          */
  367         if (!cold && (howto & RB_NOSYNC) == 0 && once == 0) {
  368                 once = 1;
  369                 bufshutdown(show_busybufs);
  370         }
  371 
  372         print_uptime();
  373 
  374         cngrab();
  375 
  376         /*
  377          * Ok, now do things that assume all filesystem activity has
  378          * been completed.
  379          */
  380         EVENTHANDLER_INVOKE(shutdown_post_sync, howto);
  381 
  382         if ((howto & (RB_HALT|RB_DUMP)) == RB_DUMP && !cold && !dumping) 
  383                 doadump(TRUE);
  384 
  385         /* Now that we're going to really halt the system... */
  386         EVENTHANDLER_INVOKE(shutdown_final, howto);
  387 
  388         for(;;) ;       /* safety against shutdown_reset not working */
  389         /* NOTREACHED */
  390 }
  391 
  392 /*
  393  * The system call that results in changing the rootfs.
  394  */
  395 static int
  396 kern_reroot(void)
  397 {
  398         struct vnode *oldrootvnode, *vp;
  399         struct mount *mp, *devmp;
  400         int error;
  401 
  402         if (curproc != initproc)
  403                 return (EPERM);
  404 
  405         /*
  406          * Mark the filesystem containing currently-running executable
  407          * (the temporary copy of init(8)) busy.
  408          */
  409         vp = curproc->p_textvp;
  410         error = vn_lock(vp, LK_SHARED);
  411         if (error != 0)
  412                 return (error);
  413         mp = vp->v_mount;
  414         error = vfs_busy(mp, MBF_NOWAIT);
  415         if (error != 0) {
  416                 vfs_ref(mp);
  417                 VOP_UNLOCK(vp, 0);
  418                 error = vfs_busy(mp, 0);
  419                 vn_lock(vp, LK_SHARED | LK_RETRY);
  420                 vfs_rel(mp);
  421                 if (error != 0) {
  422                         VOP_UNLOCK(vp, 0);
  423                         return (ENOENT);
  424                 }
  425                 if (vp->v_iflag & VI_DOOMED) {
  426                         VOP_UNLOCK(vp, 0);
  427                         vfs_unbusy(mp);
  428                         return (ENOENT);
  429                 }
  430         }
  431         VOP_UNLOCK(vp, 0);
  432 
  433         /*
  434          * Remove the filesystem containing currently-running executable
  435          * from the mount list, to prevent it from being unmounted
  436          * by vfs_unmountall(), and to avoid confusing vfs_mountroot().
  437          *
  438          * Also preserve /dev - forcibly unmounting it could cause driver
  439          * reinitialization.
  440          */
  441 
  442         vfs_ref(rootdevmp);
  443         devmp = rootdevmp;
  444         rootdevmp = NULL;
  445 
  446         mtx_lock(&mountlist_mtx);
  447         TAILQ_REMOVE(&mountlist, mp, mnt_list);
  448         TAILQ_REMOVE(&mountlist, devmp, mnt_list);
  449         mtx_unlock(&mountlist_mtx);
  450 
  451         oldrootvnode = rootvnode;
  452 
  453         /*
  454          * Unmount everything except for the two filesystems preserved above.
  455          */
  456         vfs_unmountall();
  457 
  458         /*
  459          * Add /dev back; vfs_mountroot() will move it into its new place.
  460          */
  461         mtx_lock(&mountlist_mtx);
  462         TAILQ_INSERT_HEAD(&mountlist, devmp, mnt_list);
  463         mtx_unlock(&mountlist_mtx);
  464         rootdevmp = devmp;
  465         vfs_rel(rootdevmp);
  466 
  467         /*
  468          * Mount the new rootfs.
  469          */
  470         vfs_mountroot();
  471 
  472         /*
  473          * Update all references to the old rootvnode.
  474          */
  475         mountcheckdirs(oldrootvnode, rootvnode);
  476 
  477         /*
  478          * Add the temporary filesystem back and unbusy it.
  479          */
  480         mtx_lock(&mountlist_mtx);
  481         TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
  482         mtx_unlock(&mountlist_mtx);
  483         vfs_unbusy(mp);
  484 
  485         return (0);
  486 }
  487 
  488 /*
  489  * If the shutdown was a clean halt, behave accordingly.
  490  */
  491 static void
  492 shutdown_halt(void *junk, int howto)
  493 {
  494 
  495         if (howto & RB_HALT) {
  496                 printf("\n");
  497                 printf("The operating system has halted.\n");
  498                 printf("Please press any key to reboot.\n\n");
  499                 switch (cngetc()) {
  500                 case -1:                /* No console, just die */
  501                         cpu_halt();
  502                         /* NOTREACHED */
  503                 default:
  504                         howto &= ~RB_HALT;
  505                         break;
  506                 }
  507         }
  508 }
  509 
  510 /*
  511  * Check to see if the system paniced, pause and then reboot
  512  * according to the specified delay.
  513  */
  514 static void
  515 shutdown_panic(void *junk, int howto)
  516 {
  517         int loop;
  518 
  519         if (howto & RB_DUMP) {
  520                 if (panic_reboot_wait_time != 0) {
  521                         if (panic_reboot_wait_time != -1) {
  522                                 printf("Automatic reboot in %d seconds - "
  523                                        "press a key on the console to abort\n",
  524                                         panic_reboot_wait_time);
  525                                 for (loop = panic_reboot_wait_time * 10;
  526                                      loop > 0; --loop) {
  527                                         DELAY(1000 * 100); /* 1/10th second */
  528                                         /* Did user type a key? */
  529                                         if (cncheckc() != -1)
  530                                                 break;
  531                                 }
  532                                 if (!loop)
  533                                         return;
  534                         }
  535                 } else { /* zero time specified - reboot NOW */
  536                         return;
  537                 }
  538                 printf("--> Press a key on the console to reboot,\n");
  539                 printf("--> or switch off the system now.\n");
  540                 cngetc();
  541         }
  542 }
  543 
  544 /*
  545  * Everything done, now reset
  546  */
  547 static void
  548 shutdown_reset(void *junk, int howto)
  549 {
  550 
  551         printf("Rebooting...\n");
  552         DELAY(1000000); /* wait 1 sec for printf's to complete and be read */
  553 
  554         /*
  555          * Acquiring smp_ipi_mtx here has a double effect:
  556          * - it disables interrupts avoiding CPU0 preemption
  557          *   by fast handlers (thus deadlocking  against other CPUs)
  558          * - it avoids deadlocks against smp_rendezvous() or, more 
  559          *   generally, threads busy-waiting, with this spinlock held,
  560          *   and waiting for responses by threads on other CPUs
  561          *   (ie. smp_tlb_shootdown()).
  562          *
  563          * For the !SMP case it just needs to handle the former problem.
  564          */
  565 #ifdef SMP
  566         mtx_lock_spin(&smp_ipi_mtx);
  567 #else
  568         spinlock_enter();
  569 #endif
  570 
  571         /* cpu_boot(howto); */ /* doesn't do anything at the moment */
  572         cpu_reset();
  573         /* NOTREACHED */ /* assuming reset worked */
  574 }
  575 
  576 #if defined(WITNESS) || defined(INVARIANT_SUPPORT)
  577 static int kassert_warn_only = 0;
  578 #ifdef KDB
  579 static int kassert_do_kdb = 0;
  580 #endif
  581 #ifdef KTR
  582 static int kassert_do_ktr = 0;
  583 #endif
  584 static int kassert_do_log = 1;
  585 static int kassert_log_pps_limit = 4;
  586 static int kassert_log_mute_at = 0;
  587 static int kassert_log_panic_at = 0;
  588 static int kassert_warnings = 0;
  589 
  590 SYSCTL_NODE(_debug, OID_AUTO, kassert, CTLFLAG_RW, NULL, "kassert options");
  591 
  592 SYSCTL_INT(_debug_kassert, OID_AUTO, warn_only, CTLFLAG_RWTUN,
  593     &kassert_warn_only, 0,
  594     "KASSERT triggers a panic (1) or just a warning (0)");
  595 
  596 #ifdef KDB
  597 SYSCTL_INT(_debug_kassert, OID_AUTO, do_kdb, CTLFLAG_RWTUN,
  598     &kassert_do_kdb, 0, "KASSERT will enter the debugger");
  599 #endif
  600 
  601 #ifdef KTR
  602 SYSCTL_UINT(_debug_kassert, OID_AUTO, do_ktr, CTLFLAG_RWTUN,
  603     &kassert_do_ktr, 0,
  604     "KASSERT does a KTR, set this to the KTRMASK you want");
  605 #endif
  606 
  607 SYSCTL_INT(_debug_kassert, OID_AUTO, do_log, CTLFLAG_RWTUN,
  608     &kassert_do_log, 0, "KASSERT triggers a panic (1) or just a warning (0)");
  609 
  610 SYSCTL_INT(_debug_kassert, OID_AUTO, warnings, CTLFLAG_RWTUN,
  611     &kassert_warnings, 0, "number of KASSERTs that have been triggered");
  612 
  613 SYSCTL_INT(_debug_kassert, OID_AUTO, log_panic_at, CTLFLAG_RWTUN,
  614     &kassert_log_panic_at, 0, "max number of KASSERTS before we will panic");
  615 
  616 SYSCTL_INT(_debug_kassert, OID_AUTO, log_pps_limit, CTLFLAG_RWTUN,
  617     &kassert_log_pps_limit, 0, "limit number of log messages per second");
  618 
  619 SYSCTL_INT(_debug_kassert, OID_AUTO, log_mute_at, CTLFLAG_RWTUN,
  620     &kassert_log_mute_at, 0, "max number of KASSERTS to log");
  621 
  622 static int kassert_sysctl_kassert(SYSCTL_HANDLER_ARGS);
  623 
  624 SYSCTL_PROC(_debug_kassert, OID_AUTO, kassert,
  625     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
  626     kassert_sysctl_kassert, "I", "set to trigger a test kassert");
  627 
  628 static int
  629 kassert_sysctl_kassert(SYSCTL_HANDLER_ARGS)
  630 {
  631         int error, i;
  632 
  633         error = sysctl_wire_old_buffer(req, sizeof(int));
  634         if (error == 0) {
  635                 i = 0;
  636                 error = sysctl_handle_int(oidp, &i, 0, req);
  637         }
  638         if (error != 0 || req->newptr == NULL)
  639                 return (error);
  640         KASSERT(0, ("kassert_sysctl_kassert triggered kassert %d", i));
  641         return (0);
  642 }
  643 
  644 /*
  645  * Called by KASSERT, this decides if we will panic
  646  * or if we will log via printf and/or ktr.
  647  */
  648 void
  649 kassert_panic(const char *fmt, ...)
  650 {
  651         static char buf[256];
  652         va_list ap;
  653 
  654         va_start(ap, fmt);
  655         (void)vsnprintf(buf, sizeof(buf), fmt, ap);
  656         va_end(ap);
  657 
  658         /*
  659          * panic if we're not just warning, or if we've exceeded
  660          * kassert_log_panic_at warnings.
  661          */
  662         if (!kassert_warn_only ||
  663             (kassert_log_panic_at > 0 &&
  664              kassert_warnings >= kassert_log_panic_at)) {
  665                 va_start(ap, fmt);
  666                 vpanic(fmt, ap);
  667                 /* NORETURN */
  668         }
  669 #ifdef KTR
  670         if (kassert_do_ktr)
  671                 CTR0(ktr_mask, buf);
  672 #endif /* KTR */
  673         /*
  674          * log if we've not yet met the mute limit.
  675          */
  676         if (kassert_do_log &&
  677             (kassert_log_mute_at == 0 ||
  678              kassert_warnings < kassert_log_mute_at)) {
  679                 static  struct timeval lasterr;
  680                 static  int curerr;
  681 
  682                 if (ppsratecheck(&lasterr, &curerr, kassert_log_pps_limit)) {
  683                         printf("KASSERT failed: %s\n", buf);
  684                         kdb_backtrace();
  685                 }
  686         }
  687 #ifdef KDB
  688         if (kassert_do_kdb) {
  689                 kdb_enter(KDB_WHY_KASSERT, buf);
  690         }
  691 #endif
  692         atomic_add_int(&kassert_warnings, 1);
  693 }
  694 #endif
  695 
  696 /*
  697  * Panic is called on unresolvable fatal errors.  It prints "panic: mesg",
  698  * and then reboots.  If we are called twice, then we avoid trying to sync
  699  * the disks as this often leads to recursive panics.
  700  */
  701 void
  702 panic(const char *fmt, ...)
  703 {
  704         va_list ap;
  705 
  706         va_start(ap, fmt);
  707         vpanic(fmt, ap);
  708 }
  709 
  710 void
  711 vpanic(const char *fmt, va_list ap)
  712 {
  713 #ifdef SMP
  714         cpuset_t other_cpus;
  715 #endif
  716         struct thread *td = curthread;
  717         int bootopt, newpanic;
  718         static char buf[256];
  719 
  720         spinlock_enter();
  721 
  722 #ifdef SMP
  723         /*
  724          * stop_cpus_hard(other_cpus) should prevent multiple CPUs from
  725          * concurrently entering panic.  Only the winner will proceed
  726          * further.
  727          */
  728         if (panicstr == NULL && !kdb_active) {
  729                 other_cpus = all_cpus;
  730                 CPU_CLR(PCPU_GET(cpuid), &other_cpus);
  731                 stop_cpus_hard(other_cpus);
  732         }
  733 #endif
  734 
  735         /*
  736          * Ensure that the scheduler is stopped while panicking, even if panic
  737          * has been entered from kdb.
  738          */
  739         td->td_stopsched = 1;
  740 
  741         bootopt = RB_AUTOBOOT;
  742         newpanic = 0;
  743         if (panicstr)
  744                 bootopt |= RB_NOSYNC;
  745         else {
  746                 bootopt |= RB_DUMP;
  747                 panicstr = fmt;
  748                 newpanic = 1;
  749         }
  750 
  751         if (newpanic) {
  752                 (void)vsnprintf(buf, sizeof(buf), fmt, ap);
  753                 panicstr = buf;
  754                 cngrab();
  755                 printf("panic: %s\n", buf);
  756         } else {
  757                 printf("panic: ");
  758                 vprintf(fmt, ap);
  759                 printf("\n");
  760         }
  761 #ifdef SMP
  762         printf("cpuid = %d\n", PCPU_GET(cpuid));
  763 #endif
  764 
  765 #ifdef KDB
  766         if (newpanic && trace_on_panic)
  767                 kdb_backtrace();
  768         if (debugger_on_panic)
  769                 kdb_enter(KDB_WHY_PANIC, "panic");
  770 #endif
  771         /*thread_lock(td); */
  772         td->td_flags |= TDF_INPANIC;
  773         /* thread_unlock(td); */
  774         if (!sync_on_panic)
  775                 bootopt |= RB_NOSYNC;
  776         kern_reboot(bootopt);
  777 }
  778 
  779 /*
  780  * Support for poweroff delay.
  781  *
  782  * Please note that setting this delay too short might power off your machine
  783  * before the write cache on your hard disk has been flushed, leading to
  784  * soft-updates inconsistencies.
  785  */
  786 #ifndef POWEROFF_DELAY
  787 # define POWEROFF_DELAY 5000
  788 #endif
  789 static int poweroff_delay = POWEROFF_DELAY;
  790 
  791 SYSCTL_INT(_kern_shutdown, OID_AUTO, poweroff_delay, CTLFLAG_RW,
  792     &poweroff_delay, 0, "Delay before poweroff to write disk caches (msec)");
  793 
  794 static void
  795 poweroff_wait(void *junk, int howto)
  796 {
  797 
  798         if (!(howto & RB_POWEROFF) || poweroff_delay <= 0)
  799                 return;
  800         DELAY(poweroff_delay * 1000);
  801 }
  802 
  803 /*
  804  * Some system processes (e.g. syncer) need to be stopped at appropriate
  805  * points in their main loops prior to a system shutdown, so that they
  806  * won't interfere with the shutdown process (e.g. by holding a disk buf
  807  * to cause sync to fail).  For each of these system processes, register
  808  * shutdown_kproc() as a handler for one of shutdown events.
  809  */
  810 static int kproc_shutdown_wait = 60;
  811 SYSCTL_INT(_kern_shutdown, OID_AUTO, kproc_shutdown_wait, CTLFLAG_RW,
  812     &kproc_shutdown_wait, 0, "Max wait time (sec) to stop for each process");
  813 
  814 void
  815 kproc_shutdown(void *arg, int howto)
  816 {
  817         struct proc *p;
  818         int error;
  819 
  820         if (panicstr)
  821                 return;
  822 
  823         p = (struct proc *)arg;
  824         printf("Waiting (max %d seconds) for system process `%s' to stop... ",
  825             kproc_shutdown_wait, p->p_comm);
  826         error = kproc_suspend(p, kproc_shutdown_wait * hz);
  827 
  828         if (error == EWOULDBLOCK)
  829                 printf("timed out\n");
  830         else
  831                 printf("done\n");
  832 }
  833 
  834 void
  835 kthread_shutdown(void *arg, int howto)
  836 {
  837         struct thread *td;
  838         int error;
  839 
  840         if (panicstr)
  841                 return;
  842 
  843         td = (struct thread *)arg;
  844         printf("Waiting (max %d seconds) for system thread `%s' to stop... ",
  845             kproc_shutdown_wait, td->td_name);
  846         error = kthread_suspend(td, kproc_shutdown_wait * hz);
  847 
  848         if (error == EWOULDBLOCK)
  849                 printf("timed out\n");
  850         else
  851                 printf("done\n");
  852 }
  853 
  854 static char dumpdevname[sizeof(((struct cdev*)NULL)->si_name)];
  855 SYSCTL_STRING(_kern_shutdown, OID_AUTO, dumpdevname, CTLFLAG_RD,
  856     dumpdevname, 0, "Device for kernel dumps");
  857 
  858 /* Registration of dumpers */
  859 int
  860 set_dumper(struct dumperinfo *di, const char *devname, struct thread *td)
  861 {
  862         size_t wantcopy;
  863         int error;
  864 
  865         error = priv_check(td, PRIV_SETDUMPER);
  866         if (error != 0)
  867                 return (error);
  868 
  869         if (di == NULL) {
  870                 if (dumper.blockbuf != NULL)
  871                         free(dumper.blockbuf, M_DUMPER);
  872                 bzero(&dumper, sizeof(dumper));
  873                 dumpdevname[0] = '\0';
  874                 return (0);
  875         }
  876         if (dumper.dumper != NULL)
  877                 return (EBUSY);
  878         dumper = *di;
  879         wantcopy = strlcpy(dumpdevname, devname, sizeof(dumpdevname));
  880         if (wantcopy >= sizeof(dumpdevname)) {
  881                 printf("set_dumper: device name truncated from '%s' -> '%s'\n",
  882                         devname, dumpdevname);
  883         }
  884         dumper.blockbuf = malloc(di->blocksize, M_DUMPER, M_WAITOK | M_ZERO);
  885         return (0);
  886 }
  887 
  888 /* Call dumper with bounds checking. */
  889 int
  890 dump_write(struct dumperinfo *di, void *virtual, vm_offset_t physical,
  891     off_t offset, size_t length)
  892 {
  893 
  894         if (length != 0 && (offset < di->mediaoffset ||
  895             offset - di->mediaoffset + length > di->mediasize)) {
  896                 printf("Attempt to write outside dump device boundaries.\n"
  897             "offset(%jd), mediaoffset(%jd), length(%ju), mediasize(%jd).\n",
  898                     (intmax_t)offset, (intmax_t)di->mediaoffset,
  899                     (uintmax_t)length, (intmax_t)di->mediasize);
  900                 return (ENOSPC);
  901         }
  902         return (di->dumper(di->priv, virtual, physical, offset, length));
  903 }
  904 
  905 /* Call dumper with bounds checking. */
  906 int
  907 dump_write_pad(struct dumperinfo *di, void *virtual, vm_offset_t physical,
  908     off_t offset, size_t length, size_t *size)
  909 {
  910         char *temp;
  911         int ret;
  912 
  913         if (length > di->blocksize)
  914                 return (ENOMEM);
  915 
  916         *size = di->blocksize;
  917         if (length == di->blocksize)
  918                 temp = virtual;
  919         else {
  920                 temp = di->blockbuf;
  921                 memset(temp + length, 0, di->blocksize - length);
  922                 memcpy(temp, virtual, length);
  923         }
  924         ret = dump_write(di, temp, physical, offset, *size);
  925 
  926         return (ret);
  927 }
  928 
  929 
  930 void
  931 mkdumpheader(struct kerneldumpheader *kdh, char *magic, uint32_t archver,
  932     uint64_t dumplen, uint32_t blksz)
  933 {
  934         size_t dstsize;
  935 
  936         bzero(kdh, sizeof(*kdh));
  937         strlcpy(kdh->magic, magic, sizeof(kdh->magic));
  938         strlcpy(kdh->architecture, MACHINE_ARCH, sizeof(kdh->architecture));
  939         kdh->version = htod32(KERNELDUMPVERSION);
  940         kdh->architectureversion = htod32(archver);
  941         kdh->dumplength = htod64(dumplen);
  942         kdh->dumptime = htod64(time_second);
  943         kdh->blocksize = htod32(blksz);
  944         strlcpy(kdh->hostname, prison0.pr_hostname, sizeof(kdh->hostname));
  945         dstsize = sizeof(kdh->versionstring);
  946         if (strlcpy(kdh->versionstring, version, dstsize) >= dstsize)
  947                 kdh->versionstring[dstsize - 2] = '\n';
  948         if (panicstr != NULL)
  949                 strlcpy(kdh->panicstring, panicstr, sizeof(kdh->panicstring));
  950         kdh->parity = kerneldump_parity(kdh);
  951 }
  952 
  953 #ifdef DDB
  954 DB_SHOW_COMMAND(panic, db_show_panic)
  955 {
  956 
  957         if (panicstr == NULL)
  958                 db_printf("panicstr not set\n");
  959         else
  960                 db_printf("panic: %s\n", panicstr);
  961 }
  962 #endif

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