xref: /freebsd/sys/kern/kern_shutdown.c (revision 7778ab7e0cc22f0824eb1d1047a7ef8b4785267a)
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("$FreeBSD$");
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/jail.h>
54 #include <sys/kdb.h>
55 #include <sys/kernel.h>
56 #include <sys/kerneldump.h>
57 #include <sys/kthread.h>
58 #include <sys/malloc.h>
59 #include <sys/mount.h>
60 #include <sys/priv.h>
61 #include <sys/proc.h>
62 #include <sys/reboot.h>
63 #include <sys/resourcevar.h>
64 #include <sys/sched.h>
65 #include <sys/smp.h>
66 #include <sys/sysctl.h>
67 #include <sys/sysproto.h>
68 #include <sys/vnode.h>
69 #ifdef SW_WATCHDOG
70 #include <sys/watchdog.h>
71 #endif
72 
73 #include <ddb/ddb.h>
74 
75 #include <machine/cpu.h>
76 #include <machine/pcb.h>
77 #include <machine/smp.h>
78 
79 #include <security/mac/mac_framework.h>
80 
81 #include <vm/vm.h>
82 #include <vm/vm_object.h>
83 #include <vm/vm_page.h>
84 #include <vm/vm_pager.h>
85 #include <vm/swap_pager.h>
86 
87 #include <sys/signalvar.h>
88 
89 #ifndef PANIC_REBOOT_WAIT_TIME
90 #define PANIC_REBOOT_WAIT_TIME 15 /* default to 15 seconds */
91 #endif
92 
93 /*
94  * Note that stdarg.h and the ANSI style va_start macro is used for both
95  * ANSI and traditional C compilers.
96  */
97 #include <machine/stdarg.h>
98 
99 #ifdef KDB
100 #ifdef KDB_UNATTENDED
101 int debugger_on_panic = 0;
102 #else
103 int debugger_on_panic = 1;
104 #endif
105 SYSCTL_INT(_debug, OID_AUTO, debugger_on_panic, CTLFLAG_RW | CTLFLAG_TUN,
106 	&debugger_on_panic, 0, "Run debugger on kernel panic");
107 TUNABLE_INT("debug.debugger_on_panic", &debugger_on_panic);
108 
109 #ifdef KDB_TRACE
110 static int trace_on_panic = 1;
111 #else
112 static int trace_on_panic = 0;
113 #endif
114 SYSCTL_INT(_debug, OID_AUTO, trace_on_panic, CTLFLAG_RW | CTLFLAG_TUN,
115 	&trace_on_panic, 0, "Print stack trace on kernel panic");
116 TUNABLE_INT("debug.trace_on_panic", &trace_on_panic);
117 #endif /* KDB */
118 
119 static int sync_on_panic = 0;
120 SYSCTL_INT(_kern, OID_AUTO, sync_on_panic, CTLFLAG_RW | CTLFLAG_TUN,
121 	&sync_on_panic, 0, "Do a sync before rebooting from a panic");
122 TUNABLE_INT("kern.sync_on_panic", &sync_on_panic);
123 
124 SYSCTL_NODE(_kern, OID_AUTO, shutdown, CTLFLAG_RW, 0, "Shutdown environment");
125 
126 #ifndef DIAGNOSTIC
127 static int show_busybufs;
128 #else
129 static int show_busybufs = 1;
130 #endif
131 SYSCTL_INT(_kern_shutdown, OID_AUTO, show_busybufs, CTLFLAG_RW,
132 	&show_busybufs, 0, "");
133 
134 /*
135  * Variable panicstr contains argument to first call to panic; used as flag
136  * to indicate that the kernel has already called panic.
137  */
138 const char *panicstr;
139 
140 int dumping;				/* system is dumping */
141 int rebooting;				/* system is rebooting */
142 static struct dumperinfo dumper;	/* our selected dumper */
143 
144 /* Context information for dump-debuggers. */
145 static struct pcb dumppcb;		/* Registers. */
146 static lwpid_t dumptid;			/* Thread ID. */
147 
148 static void poweroff_wait(void *, int);
149 static void shutdown_halt(void *junk, int howto);
150 static void shutdown_panic(void *junk, int howto);
151 static void shutdown_reset(void *junk, int howto);
152 
153 /* register various local shutdown events */
154 static void
155 shutdown_conf(void *unused)
156 {
157 
158 	EVENTHANDLER_REGISTER(shutdown_final, poweroff_wait, NULL,
159 	    SHUTDOWN_PRI_FIRST);
160 	EVENTHANDLER_REGISTER(shutdown_final, shutdown_halt, NULL,
161 	    SHUTDOWN_PRI_LAST + 100);
162 	EVENTHANDLER_REGISTER(shutdown_final, shutdown_panic, NULL,
163 	    SHUTDOWN_PRI_LAST + 100);
164 	EVENTHANDLER_REGISTER(shutdown_final, shutdown_reset, NULL,
165 	    SHUTDOWN_PRI_LAST + 200);
166 }
167 
168 SYSINIT(shutdown_conf, SI_SUB_INTRINSIC, SI_ORDER_ANY, shutdown_conf, NULL);
169 
170 /*
171  * The system call that results in a reboot.
172  */
173 /* ARGSUSED */
174 int
175 sys_reboot(struct thread *td, struct reboot_args *uap)
176 {
177 	int error;
178 
179 	error = 0;
180 #ifdef MAC
181 	error = mac_system_check_reboot(td->td_ucred, uap->opt);
182 #endif
183 	if (error == 0)
184 		error = priv_check(td, PRIV_REBOOT);
185 	if (error == 0) {
186 		mtx_lock(&Giant);
187 		kern_reboot(uap->opt);
188 		mtx_unlock(&Giant);
189 	}
190 	return (error);
191 }
192 
193 /*
194  * Called by events that want to shut down.. e.g  <CTL><ALT><DEL> on a PC
195  */
196 static int shutdown_howto = 0;
197 
198 void
199 shutdown_nice(int howto)
200 {
201 
202 	shutdown_howto = howto;
203 
204 	/* Send a signal to init(8) and have it shutdown the world */
205 	if (initproc != NULL) {
206 		PROC_LOCK(initproc);
207 		kern_psignal(initproc, SIGINT);
208 		PROC_UNLOCK(initproc);
209 	} else {
210 		/* No init(8) running, so simply reboot */
211 		kern_reboot(RB_NOSYNC);
212 	}
213 	return;
214 }
215 static int	waittime = -1;
216 
217 static void
218 print_uptime(void)
219 {
220 	int f;
221 	struct timespec ts;
222 
223 	getnanouptime(&ts);
224 	printf("Uptime: ");
225 	f = 0;
226 	if (ts.tv_sec >= 86400) {
227 		printf("%ldd", (long)ts.tv_sec / 86400);
228 		ts.tv_sec %= 86400;
229 		f = 1;
230 	}
231 	if (f || ts.tv_sec >= 3600) {
232 		printf("%ldh", (long)ts.tv_sec / 3600);
233 		ts.tv_sec %= 3600;
234 		f = 1;
235 	}
236 	if (f || ts.tv_sec >= 60) {
237 		printf("%ldm", (long)ts.tv_sec / 60);
238 		ts.tv_sec %= 60;
239 		f = 1;
240 	}
241 	printf("%lds\n", (long)ts.tv_sec);
242 }
243 
244 int
245 doadump(boolean_t textdump)
246 {
247 	boolean_t coredump;
248 
249 	if (dumping)
250 		return (EBUSY);
251 	if (dumper.dumper == NULL)
252 		return (ENXIO);
253 
254 	savectx(&dumppcb);
255 	dumptid = curthread->td_tid;
256 	dumping++;
257 
258 	coredump = TRUE;
259 #ifdef DDB
260 	if (textdump && textdump_pending) {
261 		coredump = FALSE;
262 		textdump_dumpsys(&dumper);
263 	}
264 #endif
265 	if (coredump)
266 		dumpsys(&dumper);
267 
268 	dumping--;
269 	return (0);
270 }
271 
272 static int
273 isbufbusy(struct buf *bp)
274 {
275 	if (((bp->b_flags & (B_INVAL | B_PERSISTENT)) == 0 &&
276 	    BUF_ISLOCKED(bp)) ||
277 	    ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
278 		return (1);
279 	return (0);
280 }
281 
282 /*
283  * Shutdown the system cleanly to prepare for reboot, halt, or power off.
284  */
285 void
286 kern_reboot(int howto)
287 {
288 	static int first_buf_printf = 1;
289 
290 #if defined(SMP)
291 	/*
292 	 * Bind us to CPU 0 so that all shutdown code runs there.  Some
293 	 * systems don't shutdown properly (i.e., ACPI power off) if we
294 	 * run on another processor.
295 	 */
296 	thread_lock(curthread);
297 	sched_bind(curthread, 0);
298 	thread_unlock(curthread);
299 	KASSERT(PCPU_GET(cpuid) == 0, ("%s: not running on cpu 0", __func__));
300 #endif
301 	/* We're in the process of rebooting. */
302 	rebooting = 1;
303 
304 	/* collect extra flags that shutdown_nice might have set */
305 	howto |= shutdown_howto;
306 
307 	/* We are out of the debugger now. */
308 	kdb_active = 0;
309 
310 	/*
311 	 * Do any callouts that should be done BEFORE syncing the filesystems.
312 	 */
313 	EVENTHANDLER_INVOKE(shutdown_pre_sync, howto);
314 
315 	/*
316 	 * Now sync filesystems
317 	 */
318 	if (!cold && (howto & RB_NOSYNC) == 0 && waittime < 0) {
319 		register struct buf *bp;
320 		int iter, nbusy, pbusy;
321 #ifndef PREEMPTION
322 		int subiter;
323 #endif
324 
325 		waittime = 0;
326 
327 #ifdef SW_WATCHDOG
328 		wdog_kern_pat(WD_LASTVAL);
329 #endif
330 		sys_sync(curthread, NULL);
331 
332 		/*
333 		 * With soft updates, some buffers that are
334 		 * written will be remarked as dirty until other
335 		 * buffers are written.
336 		 */
337 		for (iter = pbusy = 0; iter < 20; iter++) {
338 			nbusy = 0;
339 			for (bp = &buf[nbuf]; --bp >= buf; )
340 				if (isbufbusy(bp))
341 					nbusy++;
342 			if (nbusy == 0) {
343 				if (first_buf_printf)
344 					printf("All buffers synced.");
345 				break;
346 			}
347 			if (first_buf_printf) {
348 				printf("Syncing disks, buffers remaining... ");
349 				first_buf_printf = 0;
350 			}
351 			printf("%d ", nbusy);
352 			if (nbusy < pbusy)
353 				iter = 0;
354 			pbusy = nbusy;
355 #ifdef SW_WATCHDOG
356 			wdog_kern_pat(WD_LASTVAL);
357 #endif
358 			sys_sync(curthread, NULL);
359 
360 #ifdef PREEMPTION
361 			/*
362 			 * Drop Giant and spin for a while to allow
363 			 * interrupt threads to run.
364 			 */
365 			DROP_GIANT();
366 			DELAY(50000 * iter);
367 			PICKUP_GIANT();
368 #else
369 			/*
370 			 * Drop Giant and context switch several times to
371 			 * allow interrupt threads to run.
372 			 */
373 			DROP_GIANT();
374 			for (subiter = 0; subiter < 50 * iter; subiter++) {
375 				thread_lock(curthread);
376 				mi_switch(SW_VOL, NULL);
377 				thread_unlock(curthread);
378 				DELAY(1000);
379 			}
380 			PICKUP_GIANT();
381 #endif
382 		}
383 		printf("\n");
384 		/*
385 		 * Count only busy local buffers to prevent forcing
386 		 * a fsck if we're just a client of a wedged NFS server
387 		 */
388 		nbusy = 0;
389 		for (bp = &buf[nbuf]; --bp >= buf; ) {
390 			if (isbufbusy(bp)) {
391 #if 0
392 /* XXX: This is bogus.  We should probably have a BO_REMOTE flag instead */
393 				if (bp->b_dev == NULL) {
394 					TAILQ_REMOVE(&mountlist,
395 					    bp->b_vp->v_mount, mnt_list);
396 					continue;
397 				}
398 #endif
399 				nbusy++;
400 				if (show_busybufs > 0) {
401 					printf(
402 	    "%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
403 					    nbusy, bp, bp->b_vp, bp->b_flags,
404 					    (intmax_t)bp->b_blkno,
405 					    (intmax_t)bp->b_lblkno);
406 					BUF_LOCKPRINTINFO(bp);
407 					if (show_busybufs > 1)
408 						vn_printf(bp->b_vp,
409 						    "vnode content: ");
410 				}
411 			}
412 		}
413 		if (nbusy) {
414 			/*
415 			 * Failed to sync all blocks. Indicate this and don't
416 			 * unmount filesystems (thus forcing an fsck on reboot).
417 			 */
418 			printf("Giving up on %d buffers\n", nbusy);
419 			DELAY(5000000);	/* 5 seconds */
420 		} else {
421 			if (!first_buf_printf)
422 				printf("Final sync complete\n");
423 			/*
424 			 * Unmount filesystems
425 			 */
426 			if (panicstr == 0)
427 				vfs_unmountall();
428 		}
429 		swapoff_all();
430 		DELAY(100000);		/* wait for console output to finish */
431 	}
432 
433 	print_uptime();
434 
435 	/*
436 	 * Ok, now do things that assume all filesystem activity has
437 	 * been completed.
438 	 */
439 	EVENTHANDLER_INVOKE(shutdown_post_sync, howto);
440 
441 	if ((howto & (RB_HALT|RB_DUMP)) == RB_DUMP && !cold && !dumping)
442 		doadump(TRUE);
443 
444 	/* Now that we're going to really halt the system... */
445 	EVENTHANDLER_INVOKE(shutdown_final, howto);
446 
447 	for(;;) ;	/* safety against shutdown_reset not working */
448 	/* NOTREACHED */
449 }
450 
451 /*
452  * If the shutdown was a clean halt, behave accordingly.
453  */
454 static void
455 shutdown_halt(void *junk, int howto)
456 {
457 
458 	if (howto & RB_HALT) {
459 		printf("\n");
460 		printf("The operating system has halted.\n");
461 		printf("Please press any key to reboot.\n\n");
462 		switch (cngetc()) {
463 		case -1:		/* No console, just die */
464 			cpu_halt();
465 			/* NOTREACHED */
466 		default:
467 			howto &= ~RB_HALT;
468 			break;
469 		}
470 	}
471 }
472 
473 /*
474  * Check to see if the system paniced, pause and then reboot
475  * according to the specified delay.
476  */
477 static void
478 shutdown_panic(void *junk, int howto)
479 {
480 	int loop;
481 
482 	if (howto & RB_DUMP) {
483 		if (PANIC_REBOOT_WAIT_TIME != 0) {
484 			if (PANIC_REBOOT_WAIT_TIME != -1) {
485 				printf("Automatic reboot in %d seconds - "
486 				       "press a key on the console to abort\n",
487 					PANIC_REBOOT_WAIT_TIME);
488 				for (loop = PANIC_REBOOT_WAIT_TIME * 10;
489 				     loop > 0; --loop) {
490 					DELAY(1000 * 100); /* 1/10th second */
491 					/* Did user type a key? */
492 					if (cncheckc() != -1)
493 						break;
494 				}
495 				if (!loop)
496 					return;
497 			}
498 		} else { /* zero time specified - reboot NOW */
499 			return;
500 		}
501 		printf("--> Press a key on the console to reboot,\n");
502 		printf("--> or switch off the system now.\n");
503 		cngetc();
504 	}
505 }
506 
507 /*
508  * Everything done, now reset
509  */
510 static void
511 shutdown_reset(void *junk, int howto)
512 {
513 
514 	printf("Rebooting...\n");
515 	DELAY(1000000);	/* wait 1 sec for printf's to complete and be read */
516 
517 	/*
518 	 * Acquiring smp_ipi_mtx here has a double effect:
519 	 * - it disables interrupts avoiding CPU0 preemption
520 	 *   by fast handlers (thus deadlocking  against other CPUs)
521 	 * - it avoids deadlocks against smp_rendezvous() or, more
522 	 *   generally, threads busy-waiting, with this spinlock held,
523 	 *   and waiting for responses by threads on other CPUs
524 	 *   (ie. smp_tlb_shootdown()).
525 	 *
526 	 * For the !SMP case it just needs to handle the former problem.
527 	 */
528 #ifdef SMP
529 	mtx_lock_spin(&smp_ipi_mtx);
530 #else
531 	spinlock_enter();
532 #endif
533 
534 	/* cpu_boot(howto); */ /* doesn't do anything at the moment */
535 	cpu_reset();
536 	/* NOTREACHED */ /* assuming reset worked */
537 }
538 
539 /*
540  * Panic is called on unresolvable fatal errors.  It prints "panic: mesg",
541  * and then reboots.  If we are called twice, then we avoid trying to sync
542  * the disks as this often leads to recursive panics.
543  */
544 void
545 panic(const char *fmt, ...)
546 {
547 #ifdef SMP
548 	static volatile u_int panic_cpu = NOCPU;
549 #endif
550 	struct thread *td = curthread;
551 	int bootopt, newpanic;
552 	va_list ap;
553 	static char buf[256];
554 
555 	critical_enter();
556 #ifdef SMP
557 	/*
558 	 * We don't want multiple CPU's to panic at the same time, so we
559 	 * use panic_cpu as a simple spinlock.  We have to keep checking
560 	 * panic_cpu if we are spinning in case the panic on the first
561 	 * CPU is canceled.
562 	 */
563 	if (panic_cpu != PCPU_GET(cpuid))
564 		while (atomic_cmpset_int(&panic_cpu, NOCPU,
565 		    PCPU_GET(cpuid)) == 0)
566 			while (panic_cpu != NOCPU)
567 				; /* nothing */
568 #endif
569 
570 	bootopt = RB_AUTOBOOT;
571 	newpanic = 0;
572 	if (panicstr)
573 		bootopt |= RB_NOSYNC;
574 	else {
575 		bootopt |= RB_DUMP;
576 		panicstr = fmt;
577 		newpanic = 1;
578 	}
579 
580 	va_start(ap, fmt);
581 	if (newpanic) {
582 		(void)vsnprintf(buf, sizeof(buf), fmt, ap);
583 		panicstr = buf;
584 		printf("panic: %s\n", buf);
585 	} else {
586 		printf("panic: ");
587 		vprintf(fmt, ap);
588 		printf("\n");
589 	}
590 	va_end(ap);
591 #ifdef SMP
592 	printf("cpuid = %d\n", PCPU_GET(cpuid));
593 #endif
594 
595 #ifdef KDB
596 	if (newpanic && trace_on_panic)
597 		kdb_backtrace();
598 	if (debugger_on_panic)
599 		kdb_enter(KDB_WHY_PANIC, "panic");
600 #endif
601 	/*thread_lock(td); */
602 	td->td_flags |= TDF_INPANIC;
603 	/* thread_unlock(td); */
604 	if (!sync_on_panic)
605 		bootopt |= RB_NOSYNC;
606 	critical_exit();
607 	kern_reboot(bootopt);
608 }
609 
610 /*
611  * Support for poweroff delay.
612  *
613  * Please note that setting this delay too short might power off your machine
614  * before the write cache on your hard disk has been flushed, leading to
615  * soft-updates inconsistencies.
616  */
617 #ifndef POWEROFF_DELAY
618 # define POWEROFF_DELAY 5000
619 #endif
620 static int poweroff_delay = POWEROFF_DELAY;
621 
622 SYSCTL_INT(_kern_shutdown, OID_AUTO, poweroff_delay, CTLFLAG_RW,
623 	&poweroff_delay, 0, "");
624 
625 static void
626 poweroff_wait(void *junk, int howto)
627 {
628 
629 	if (!(howto & RB_POWEROFF) || poweroff_delay <= 0)
630 		return;
631 	DELAY(poweroff_delay * 1000);
632 }
633 
634 /*
635  * Some system processes (e.g. syncer) need to be stopped at appropriate
636  * points in their main loops prior to a system shutdown, so that they
637  * won't interfere with the shutdown process (e.g. by holding a disk buf
638  * to cause sync to fail).  For each of these system processes, register
639  * shutdown_kproc() as a handler for one of shutdown events.
640  */
641 static int kproc_shutdown_wait = 60;
642 SYSCTL_INT(_kern_shutdown, OID_AUTO, kproc_shutdown_wait, CTLFLAG_RW,
643     &kproc_shutdown_wait, 0, "");
644 
645 void
646 kproc_shutdown(void *arg, int howto)
647 {
648 	struct proc *p;
649 	int error;
650 
651 	if (panicstr)
652 		return;
653 
654 	p = (struct proc *)arg;
655 	printf("Waiting (max %d seconds) for system process `%s' to stop...",
656 	    kproc_shutdown_wait, p->p_comm);
657 	error = kproc_suspend(p, kproc_shutdown_wait * hz);
658 
659 	if (error == EWOULDBLOCK)
660 		printf("timed out\n");
661 	else
662 		printf("done\n");
663 }
664 
665 void
666 kthread_shutdown(void *arg, int howto)
667 {
668 	struct thread *td;
669 	int error;
670 
671 	if (panicstr)
672 		return;
673 
674 	td = (struct thread *)arg;
675 	printf("Waiting (max %d seconds) for system thread `%s' to stop...",
676 	    kproc_shutdown_wait, td->td_name);
677 	error = kthread_suspend(td, kproc_shutdown_wait * hz);
678 
679 	if (error == EWOULDBLOCK)
680 		printf("timed out\n");
681 	else
682 		printf("done\n");
683 }
684 
685 /* Registration of dumpers */
686 int
687 set_dumper(struct dumperinfo *di)
688 {
689 
690 	if (di == NULL) {
691 		bzero(&dumper, sizeof dumper);
692 		return (0);
693 	}
694 	if (dumper.dumper != NULL)
695 		return (EBUSY);
696 	dumper = *di;
697 	return (0);
698 }
699 
700 /* Call dumper with bounds checking. */
701 int
702 dump_write(struct dumperinfo *di, void *virtual, vm_offset_t physical,
703     off_t offset, size_t length)
704 {
705 
706 	if (length != 0 && (offset < di->mediaoffset ||
707 	    offset - di->mediaoffset + length > di->mediasize)) {
708 		printf("Attempt to write outside dump device boundaries.\n"
709 	    "offset(%jd), mediaoffset(%jd), length(%ju), mediasize(%jd).\n",
710 		    (intmax_t)offset, (intmax_t)di->mediaoffset,
711 		    (uintmax_t)length, (intmax_t)di->mediasize);
712 		return (ENOSPC);
713 	}
714 	return (di->dumper(di->priv, virtual, physical, offset, length));
715 }
716 
717 void
718 mkdumpheader(struct kerneldumpheader *kdh, char *magic, uint32_t archver,
719     uint64_t dumplen, uint32_t blksz)
720 {
721 
722 	bzero(kdh, sizeof(*kdh));
723 	strncpy(kdh->magic, magic, sizeof(kdh->magic));
724 	strncpy(kdh->architecture, MACHINE_ARCH, sizeof(kdh->architecture));
725 	kdh->version = htod32(KERNELDUMPVERSION);
726 	kdh->architectureversion = htod32(archver);
727 	kdh->dumplength = htod64(dumplen);
728 	kdh->dumptime = htod64(time_second);
729 	kdh->blocksize = htod32(blksz);
730 	strncpy(kdh->hostname, prison0.pr_hostname, sizeof(kdh->hostname));
731 	strncpy(kdh->versionstring, version, sizeof(kdh->versionstring));
732 	if (panicstr != NULL)
733 		strncpy(kdh->panicstring, panicstr, sizeof(kdh->panicstring));
734 	kdh->parity = kerneldump_parity(kdh);
735 }
736