xref: /freebsd/sys/kern/kern_shutdown.c (revision 6f9c8e5b074419423648ffb89b83fd2f257e90b7)
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_show_busybufs.h"
44 #include "opt_sched.h"
45 #include "opt_watchdog.h"
46 
47 #include <sys/param.h>
48 #include <sys/systm.h>
49 #include <sys/bio.h>
50 #include <sys/buf.h>
51 #include <sys/conf.h>
52 #include <sys/cons.h>
53 #include <sys/eventhandler.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/malloc.h>
60 #include <sys/mount.h>
61 #include <sys/priv.h>
62 #include <sys/proc.h>
63 #include <sys/reboot.h>
64 #include <sys/resourcevar.h>
65 #include <sys/sched.h>
66 #include <sys/smp.h>
67 #include <sys/sysctl.h>
68 #include <sys/sysproto.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 /*
127  * Variable panicstr contains argument to first call to panic; used as flag
128  * to indicate that the kernel has already called panic.
129  */
130 const char *panicstr;
131 
132 int dumping;				/* system is dumping */
133 int rebooting;				/* system is rebooting */
134 static struct dumperinfo dumper;	/* our selected dumper */
135 
136 /* Context information for dump-debuggers. */
137 static struct pcb dumppcb;		/* Registers. */
138 static lwpid_t dumptid;			/* Thread ID. */
139 
140 static void poweroff_wait(void *, int);
141 static void shutdown_halt(void *junk, int howto);
142 static void shutdown_panic(void *junk, int howto);
143 static void shutdown_reset(void *junk, int howto);
144 
145 /* register various local shutdown events */
146 static void
147 shutdown_conf(void *unused)
148 {
149 
150 	EVENTHANDLER_REGISTER(shutdown_final, poweroff_wait, NULL,
151 	    SHUTDOWN_PRI_FIRST);
152 	EVENTHANDLER_REGISTER(shutdown_final, shutdown_halt, NULL,
153 	    SHUTDOWN_PRI_LAST + 100);
154 	EVENTHANDLER_REGISTER(shutdown_final, shutdown_panic, NULL,
155 	    SHUTDOWN_PRI_LAST + 100);
156 	EVENTHANDLER_REGISTER(shutdown_final, shutdown_reset, NULL,
157 	    SHUTDOWN_PRI_LAST + 200);
158 }
159 
160 SYSINIT(shutdown_conf, SI_SUB_INTRINSIC, SI_ORDER_ANY, shutdown_conf, NULL);
161 
162 /*
163  * The system call that results in a reboot.
164  */
165 /* ARGSUSED */
166 int
167 reboot(struct thread *td, struct reboot_args *uap)
168 {
169 	int error;
170 
171 	error = 0;
172 #ifdef MAC
173 	error = mac_system_check_reboot(td->td_ucred, uap->opt);
174 #endif
175 	if (error == 0)
176 		error = priv_check(td, PRIV_REBOOT);
177 	if (error == 0) {
178 		mtx_lock(&Giant);
179 		kern_reboot(uap->opt);
180 		mtx_unlock(&Giant);
181 	}
182 	return (error);
183 }
184 
185 /*
186  * Called by events that want to shut down.. e.g  <CTL><ALT><DEL> on a PC
187  */
188 static int shutdown_howto = 0;
189 
190 void
191 shutdown_nice(int howto)
192 {
193 
194 	shutdown_howto = howto;
195 
196 	/* Send a signal to init(8) and have it shutdown the world */
197 	if (initproc != NULL) {
198 		PROC_LOCK(initproc);
199 		psignal(initproc, SIGINT);
200 		PROC_UNLOCK(initproc);
201 	} else {
202 		/* No init(8) running, so simply reboot */
203 		kern_reboot(RB_NOSYNC);
204 	}
205 	return;
206 }
207 static int	waittime = -1;
208 
209 static void
210 print_uptime(void)
211 {
212 	int f;
213 	struct timespec ts;
214 
215 	getnanouptime(&ts);
216 	printf("Uptime: ");
217 	f = 0;
218 	if (ts.tv_sec >= 86400) {
219 		printf("%ldd", (long)ts.tv_sec / 86400);
220 		ts.tv_sec %= 86400;
221 		f = 1;
222 	}
223 	if (f || ts.tv_sec >= 3600) {
224 		printf("%ldh", (long)ts.tv_sec / 3600);
225 		ts.tv_sec %= 3600;
226 		f = 1;
227 	}
228 	if (f || ts.tv_sec >= 60) {
229 		printf("%ldm", (long)ts.tv_sec / 60);
230 		ts.tv_sec %= 60;
231 		f = 1;
232 	}
233 	printf("%lds\n", (long)ts.tv_sec);
234 }
235 
236 int
237 doadump(boolean_t textdump)
238 {
239 	boolean_t coredump;
240 
241 	if (dumping)
242 		return (EBUSY);
243 	if (dumper.dumper == NULL)
244 		return (ENXIO);
245 
246 	savectx(&dumppcb);
247 	dumptid = curthread->td_tid;
248 	dumping++;
249 
250 	coredump = TRUE;
251 #ifdef DDB
252 	if (textdump && textdump_pending) {
253 		coredump = FALSE;
254 		textdump_dumpsys(&dumper);
255 	}
256 #endif
257 	if (coredump)
258 		dumpsys(&dumper);
259 
260 	dumping--;
261 	return (0);
262 }
263 
264 static int
265 isbufbusy(struct buf *bp)
266 {
267 	if (((bp->b_flags & (B_INVAL | B_PERSISTENT)) == 0 &&
268 	    BUF_ISLOCKED(bp)) ||
269 	    ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
270 		return (1);
271 	return (0);
272 }
273 
274 /*
275  * Shutdown the system cleanly to prepare for reboot, halt, or power off.
276  */
277 void
278 kern_reboot(int howto)
279 {
280 	static int first_buf_printf = 1;
281 
282 #if defined(SMP)
283 	/*
284 	 * Bind us to CPU 0 so that all shutdown code runs there.  Some
285 	 * systems don't shutdown properly (i.e., ACPI power off) if we
286 	 * run on another processor.
287 	 */
288 	thread_lock(curthread);
289 	sched_bind(curthread, 0);
290 	thread_unlock(curthread);
291 	KASSERT(PCPU_GET(cpuid) == 0, ("%s: not running on cpu 0", __func__));
292 #endif
293 	/* We're in the process of rebooting. */
294 	rebooting = 1;
295 
296 	/* collect extra flags that shutdown_nice might have set */
297 	howto |= shutdown_howto;
298 
299 	/* We are out of the debugger now. */
300 	kdb_active = 0;
301 
302 	/*
303 	 * Do any callouts that should be done BEFORE syncing the filesystems.
304 	 */
305 	EVENTHANDLER_INVOKE(shutdown_pre_sync, howto);
306 
307 	/*
308 	 * Now sync filesystems
309 	 */
310 	if (!cold && (howto & RB_NOSYNC) == 0 && waittime < 0) {
311 		register struct buf *bp;
312 		int iter, nbusy, pbusy;
313 #ifndef PREEMPTION
314 		int subiter;
315 #endif
316 
317 		waittime = 0;
318 
319 #ifdef SW_WATCHDOG
320 		wdog_kern_pat(WD_LASTVAL);
321 #endif
322 		sync(curthread, NULL);
323 
324 		/*
325 		 * With soft updates, some buffers that are
326 		 * written will be remarked as dirty until other
327 		 * buffers are written.
328 		 */
329 		for (iter = pbusy = 0; iter < 20; iter++) {
330 			nbusy = 0;
331 			for (bp = &buf[nbuf]; --bp >= buf; )
332 				if (isbufbusy(bp))
333 					nbusy++;
334 			if (nbusy == 0) {
335 				if (first_buf_printf)
336 					printf("All buffers synced.");
337 				break;
338 			}
339 			if (first_buf_printf) {
340 				printf("Syncing disks, buffers remaining... ");
341 				first_buf_printf = 0;
342 			}
343 			printf("%d ", nbusy);
344 			if (nbusy < pbusy)
345 				iter = 0;
346 			pbusy = nbusy;
347 #ifdef SW_WATCHDOG
348 			wdog_kern_pat(WD_LASTVAL);
349 #endif
350 			sync(curthread, NULL);
351 
352 #ifdef PREEMPTION
353 			/*
354 			 * Drop Giant and spin for a while to allow
355 			 * interrupt threads to run.
356 			 */
357 			DROP_GIANT();
358 			DELAY(50000 * iter);
359 			PICKUP_GIANT();
360 #else
361 			/*
362 			 * Drop Giant and context switch several times to
363 			 * allow interrupt threads to run.
364 			 */
365 			DROP_GIANT();
366 			for (subiter = 0; subiter < 50 * iter; subiter++) {
367 				thread_lock(curthread);
368 				mi_switch(SW_VOL, NULL);
369 				thread_unlock(curthread);
370 				DELAY(1000);
371 			}
372 			PICKUP_GIANT();
373 #endif
374 		}
375 		printf("\n");
376 		/*
377 		 * Count only busy local buffers to prevent forcing
378 		 * a fsck if we're just a client of a wedged NFS server
379 		 */
380 		nbusy = 0;
381 		for (bp = &buf[nbuf]; --bp >= buf; ) {
382 			if (isbufbusy(bp)) {
383 #if 0
384 /* XXX: This is bogus.  We should probably have a BO_REMOTE flag instead */
385 				if (bp->b_dev == NULL) {
386 					TAILQ_REMOVE(&mountlist,
387 					    bp->b_vp->v_mount, mnt_list);
388 					continue;
389 				}
390 #endif
391 				nbusy++;
392 #if defined(SHOW_BUSYBUFS) || defined(DIAGNOSTIC)
393 				printf(
394 			    "%d: bufobj:%p, flags:%0x, blkno:%ld, lblkno:%ld\n",
395 				    nbusy, bp->b_bufobj,
396 				    bp->b_flags, (long)bp->b_blkno,
397 				    (long)bp->b_lblkno);
398 #endif
399 			}
400 		}
401 		if (nbusy) {
402 			/*
403 			 * Failed to sync all blocks. Indicate this and don't
404 			 * unmount filesystems (thus forcing an fsck on reboot).
405 			 */
406 			printf("Giving up on %d buffers\n", nbusy);
407 			DELAY(5000000);	/* 5 seconds */
408 		} else {
409 			if (!first_buf_printf)
410 				printf("Final sync complete\n");
411 			/*
412 			 * Unmount filesystems
413 			 */
414 			if (panicstr == 0)
415 				vfs_unmountall();
416 		}
417 		swapoff_all();
418 		DELAY(100000);		/* wait for console output to finish */
419 	}
420 
421 	print_uptime();
422 
423 	/*
424 	 * Ok, now do things that assume all filesystem activity has
425 	 * been completed.
426 	 */
427 	EVENTHANDLER_INVOKE(shutdown_post_sync, howto);
428 
429 	if ((howto & (RB_HALT|RB_DUMP)) == RB_DUMP && !cold && !dumping)
430 		doadump(TRUE);
431 
432 	/* Now that we're going to really halt the system... */
433 	EVENTHANDLER_INVOKE(shutdown_final, howto);
434 
435 	for(;;) ;	/* safety against shutdown_reset not working */
436 	/* NOTREACHED */
437 }
438 
439 /*
440  * If the shutdown was a clean halt, behave accordingly.
441  */
442 static void
443 shutdown_halt(void *junk, int howto)
444 {
445 
446 	if (howto & RB_HALT) {
447 		printf("\n");
448 		printf("The operating system has halted.\n");
449 		printf("Please press any key to reboot.\n\n");
450 		switch (cngetc()) {
451 		case -1:		/* No console, just die */
452 			cpu_halt();
453 			/* NOTREACHED */
454 		default:
455 			howto &= ~RB_HALT;
456 			break;
457 		}
458 	}
459 }
460 
461 /*
462  * Check to see if the system paniced, pause and then reboot
463  * according to the specified delay.
464  */
465 static void
466 shutdown_panic(void *junk, int howto)
467 {
468 	int loop;
469 
470 	if (howto & RB_DUMP) {
471 		if (PANIC_REBOOT_WAIT_TIME != 0) {
472 			if (PANIC_REBOOT_WAIT_TIME != -1) {
473 				printf("Automatic reboot in %d seconds - "
474 				       "press a key on the console to abort\n",
475 					PANIC_REBOOT_WAIT_TIME);
476 				for (loop = PANIC_REBOOT_WAIT_TIME * 10;
477 				     loop > 0; --loop) {
478 					DELAY(1000 * 100); /* 1/10th second */
479 					/* Did user type a key? */
480 					if (cncheckc() != -1)
481 						break;
482 				}
483 				if (!loop)
484 					return;
485 			}
486 		} else { /* zero time specified - reboot NOW */
487 			return;
488 		}
489 		printf("--> Press a key on the console to reboot,\n");
490 		printf("--> or switch off the system now.\n");
491 		cngetc();
492 	}
493 }
494 
495 /*
496  * Everything done, now reset
497  */
498 static void
499 shutdown_reset(void *junk, int howto)
500 {
501 
502 	printf("Rebooting...\n");
503 	DELAY(1000000);	/* wait 1 sec for printf's to complete and be read */
504 
505 	/*
506 	 * Acquiring smp_ipi_mtx here has a double effect:
507 	 * - it disables interrupts avoiding CPU0 preemption
508 	 *   by fast handlers (thus deadlocking  against other CPUs)
509 	 * - it avoids deadlocks against smp_rendezvous() or, more
510 	 *   generally, threads busy-waiting, with this spinlock held,
511 	 *   and waiting for responses by threads on other CPUs
512 	 *   (ie. smp_tlb_shootdown()).
513 	 *
514 	 * For the !SMP case it just needs to handle the former problem.
515 	 */
516 #ifdef SMP
517 	mtx_lock_spin(&smp_ipi_mtx);
518 #else
519 	spinlock_enter();
520 #endif
521 
522 	/* cpu_boot(howto); */ /* doesn't do anything at the moment */
523 	cpu_reset();
524 	/* NOTREACHED */ /* assuming reset worked */
525 }
526 
527 /*
528  * Panic is called on unresolvable fatal errors.  It prints "panic: mesg",
529  * and then reboots.  If we are called twice, then we avoid trying to sync
530  * the disks as this often leads to recursive panics.
531  */
532 void
533 panic(const char *fmt, ...)
534 {
535 #ifdef SMP
536 	static volatile u_int panic_cpu = NOCPU;
537 #endif
538 	struct thread *td = curthread;
539 	int bootopt, newpanic;
540 	va_list ap;
541 	static char buf[256];
542 
543 	critical_enter();
544 #ifdef SMP
545 	/*
546 	 * We don't want multiple CPU's to panic at the same time, so we
547 	 * use panic_cpu as a simple spinlock.  We have to keep checking
548 	 * panic_cpu if we are spinning in case the panic on the first
549 	 * CPU is canceled.
550 	 */
551 	if (panic_cpu != PCPU_GET(cpuid))
552 		while (atomic_cmpset_int(&panic_cpu, NOCPU,
553 		    PCPU_GET(cpuid)) == 0)
554 			while (panic_cpu != NOCPU)
555 				; /* nothing */
556 #endif
557 
558 	bootopt = RB_AUTOBOOT;
559 	newpanic = 0;
560 	if (panicstr)
561 		bootopt |= RB_NOSYNC;
562 	else {
563 		bootopt |= RB_DUMP;
564 		panicstr = fmt;
565 		newpanic = 1;
566 	}
567 
568 	va_start(ap, fmt);
569 	if (newpanic) {
570 		(void)vsnprintf(buf, sizeof(buf), fmt, ap);
571 		panicstr = buf;
572 		printf("panic: %s\n", buf);
573 	} else {
574 		printf("panic: ");
575 		vprintf(fmt, ap);
576 		printf("\n");
577 	}
578 	va_end(ap);
579 #ifdef SMP
580 	printf("cpuid = %d\n", PCPU_GET(cpuid));
581 #endif
582 
583 #ifdef KDB
584 	if (newpanic && trace_on_panic)
585 		kdb_backtrace();
586 	if (debugger_on_panic)
587 		kdb_enter(KDB_WHY_PANIC, "panic");
588 #ifdef RESTARTABLE_PANICS
589 	/* See if the user aborted the panic, in which case we continue. */
590 	if (panicstr == NULL) {
591 #ifdef SMP
592 		atomic_store_rel_int(&panic_cpu, NOCPU);
593 #endif
594 		return;
595 	}
596 #endif
597 #endif
598 	/*thread_lock(td); */
599 	td->td_flags |= TDF_INPANIC;
600 	/* thread_unlock(td); */
601 	if (!sync_on_panic)
602 		bootopt |= RB_NOSYNC;
603 	critical_exit();
604 	kern_reboot(bootopt);
605 }
606 
607 /*
608  * Support for poweroff delay.
609  *
610  * Please note that setting this delay too short might power off your machine
611  * before the write cache on your hard disk has been flushed, leading to
612  * soft-updates inconsistencies.
613  */
614 #ifndef POWEROFF_DELAY
615 # define POWEROFF_DELAY 5000
616 #endif
617 static int poweroff_delay = POWEROFF_DELAY;
618 
619 SYSCTL_INT(_kern_shutdown, OID_AUTO, poweroff_delay, CTLFLAG_RW,
620 	&poweroff_delay, 0, "");
621 
622 static void
623 poweroff_wait(void *junk, int howto)
624 {
625 
626 	if (!(howto & RB_POWEROFF) || poweroff_delay <= 0)
627 		return;
628 	DELAY(poweroff_delay * 1000);
629 }
630 
631 /*
632  * Some system processes (e.g. syncer) need to be stopped at appropriate
633  * points in their main loops prior to a system shutdown, so that they
634  * won't interfere with the shutdown process (e.g. by holding a disk buf
635  * to cause sync to fail).  For each of these system processes, register
636  * shutdown_kproc() as a handler for one of shutdown events.
637  */
638 static int kproc_shutdown_wait = 60;
639 SYSCTL_INT(_kern_shutdown, OID_AUTO, kproc_shutdown_wait, CTLFLAG_RW,
640     &kproc_shutdown_wait, 0, "");
641 
642 void
643 kproc_shutdown(void *arg, int howto)
644 {
645 	struct proc *p;
646 	int error;
647 
648 	if (panicstr)
649 		return;
650 
651 	p = (struct proc *)arg;
652 	printf("Waiting (max %d seconds) for system process `%s' to stop...",
653 	    kproc_shutdown_wait, p->p_comm);
654 	error = kproc_suspend(p, kproc_shutdown_wait * hz);
655 
656 	if (error == EWOULDBLOCK)
657 		printf("timed out\n");
658 	else
659 		printf("done\n");
660 }
661 
662 void
663 kthread_shutdown(void *arg, int howto)
664 {
665 	struct thread *td;
666 	int error;
667 
668 	if (panicstr)
669 		return;
670 
671 	td = (struct thread *)arg;
672 	printf("Waiting (max %d seconds) for system thread `%s' to stop...",
673 	    kproc_shutdown_wait, td->td_name);
674 	error = kthread_suspend(td, kproc_shutdown_wait * hz);
675 
676 	if (error == EWOULDBLOCK)
677 		printf("timed out\n");
678 	else
679 		printf("done\n");
680 }
681 
682 /* Registration of dumpers */
683 int
684 set_dumper(struct dumperinfo *di)
685 {
686 
687 	if (di == NULL) {
688 		bzero(&dumper, sizeof dumper);
689 		return (0);
690 	}
691 	if (dumper.dumper != NULL)
692 		return (EBUSY);
693 	dumper = *di;
694 	return (0);
695 }
696 
697 /* Call dumper with bounds checking. */
698 int
699 dump_write(struct dumperinfo *di, void *virtual, vm_offset_t physical,
700     off_t offset, size_t length)
701 {
702 
703 	if (length != 0 && (offset < di->mediaoffset ||
704 	    offset - di->mediaoffset + length > di->mediasize)) {
705 		printf("Attempt to write outside dump device boundaries.\n");
706 		return (ENXIO);
707 	}
708 	return (di->dumper(di->priv, virtual, physical, offset, length));
709 }
710 
711 void
712 mkdumpheader(struct kerneldumpheader *kdh, char *magic, uint32_t archver,
713     uint64_t dumplen, uint32_t blksz)
714 {
715 
716 	bzero(kdh, sizeof(*kdh));
717 	strncpy(kdh->magic, magic, sizeof(kdh->magic));
718 	strncpy(kdh->architecture, MACHINE_ARCH, sizeof(kdh->architecture));
719 	kdh->version = htod32(KERNELDUMPVERSION);
720 	kdh->architectureversion = htod32(archver);
721 	kdh->dumplength = htod64(dumplen);
722 	kdh->dumptime = htod64(time_second);
723 	kdh->blocksize = htod32(blksz);
724 	strncpy(kdh->hostname, prison0.pr_hostname, sizeof(kdh->hostname));
725 	strncpy(kdh->versionstring, version, sizeof(kdh->versionstring));
726 	if (panicstr != NULL)
727 		strncpy(kdh->panicstring, panicstr, sizeof(kdh->panicstring));
728 	kdh->parity = kerneldump_parity(kdh);
729 }
730