xref: /freebsd/lib/libkvm/kvm.c (revision 1f4bcc459a76b7aa664f3fd557684cd0ba6da352)
1 /*-
2  * Copyright (c) 1989, 1992, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software developed by the Computer Systems
6  * Engineering group at Lawrence Berkeley Laboratory under DARPA contract
7  * BG 91-66 and contributed to Berkeley.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36 
37 #if defined(LIBC_SCCS) && !defined(lint)
38 #if 0
39 static char sccsid[] = "@(#)kvm.c	8.2 (Berkeley) 2/13/94";
40 #endif
41 #endif /* LIBC_SCCS and not lint */
42 
43 #include <sys/param.h>
44 #include <sys/fnv_hash.h>
45 
46 #define	_WANT_VNET
47 
48 #include <sys/user.h>
49 #include <sys/linker.h>
50 #include <sys/pcpu.h>
51 #include <sys/stat.h>
52 
53 #include <net/vnet.h>
54 
55 #include <fcntl.h>
56 #include <kvm.h>
57 #include <limits.h>
58 #include <paths.h>
59 #include <stdint.h>
60 #include <stdio.h>
61 #include <stdlib.h>
62 #include <string.h>
63 #include <unistd.h>
64 
65 #include "kvm_private.h"
66 
67 SET_DECLARE(kvm_arch, struct kvm_arch);
68 
69 /* from src/lib/libc/gen/nlist.c */
70 int __fdnlist(int, struct nlist *);
71 
72 static int
73 kvm_fdnlist(kvm_t *kd, struct kvm_nlist *list)
74 {
75 	kvaddr_t addr;
76 	int error, nfail;
77 
78 	if (kd->resolve_symbol == NULL) {
79 		struct nlist *nl;
80 		int count, i;
81 
82 		for (count = 0; list[count].n_name != NULL &&
83 		     list[count].n_name[0] != '\0'; count++)
84 			;
85 		nl = calloc(count + 1, sizeof(*nl));
86 		for (i = 0; i < count; i++)
87 			nl[i].n_name = list[i].n_name;
88 		nfail = __fdnlist(kd->nlfd, nl);
89 		for (i = 0; i < count; i++) {
90 			list[i].n_type = nl[i].n_type;
91 			list[i].n_value = nl[i].n_value;
92 		}
93 		free(nl);
94 		return (nfail);
95 	}
96 
97 	nfail = 0;
98 	while (list->n_name != NULL && list->n_name[0] != '\0') {
99 		error = kd->resolve_symbol(list->n_name, &addr);
100 		if (error != 0) {
101 			nfail++;
102 			list->n_value = 0;
103 			list->n_type = 0;
104 		} else {
105 			list->n_value = addr;
106 			list->n_type = N_DATA | N_EXT;
107 		}
108 		list++;
109 	}
110 	return (nfail);
111 }
112 
113 char *
114 kvm_geterr(kvm_t *kd)
115 {
116 	return (kd->errbuf);
117 }
118 
119 #include <stdarg.h>
120 
121 /*
122  * Report an error using printf style arguments.  "program" is kd->program
123  * on hard errors, and 0 on soft errors, so that under sun error emulation,
124  * only hard errors are printed out (otherwise, programs like gdb will
125  * generate tons of error messages when trying to access bogus pointers).
126  */
127 void
128 _kvm_err(kvm_t *kd, const char *program, const char *fmt, ...)
129 {
130 	va_list ap;
131 
132 	va_start(ap, fmt);
133 	if (program != NULL) {
134 		(void)fprintf(stderr, "%s: ", program);
135 		(void)vfprintf(stderr, fmt, ap);
136 		(void)fputc('\n', stderr);
137 	} else
138 		(void)vsnprintf(kd->errbuf,
139 		    sizeof(kd->errbuf), fmt, ap);
140 
141 	va_end(ap);
142 }
143 
144 void
145 _kvm_syserr(kvm_t *kd, const char *program, const char *fmt, ...)
146 {
147 	va_list ap;
148 	int n;
149 
150 	va_start(ap, fmt);
151 	if (program != NULL) {
152 		(void)fprintf(stderr, "%s: ", program);
153 		(void)vfprintf(stderr, fmt, ap);
154 		(void)fprintf(stderr, ": %s\n", strerror(errno));
155 	} else {
156 		char *cp = kd->errbuf;
157 
158 		(void)vsnprintf(cp, sizeof(kd->errbuf), fmt, ap);
159 		n = strlen(cp);
160 		(void)snprintf(&cp[n], sizeof(kd->errbuf) - n, ": %s",
161 		    strerror(errno));
162 	}
163 	va_end(ap);
164 }
165 
166 void *
167 _kvm_malloc(kvm_t *kd, size_t n)
168 {
169 	void *p;
170 
171 	if ((p = calloc(n, sizeof(char))) == NULL)
172 		_kvm_err(kd, kd->program, "can't allocate %zu bytes: %s",
173 			 n, strerror(errno));
174 	return (p);
175 }
176 
177 static int
178 _kvm_read_kernel_ehdr(kvm_t *kd)
179 {
180 	Elf *elf;
181 
182 	if (elf_version(EV_CURRENT) == EV_NONE) {
183 		_kvm_err(kd, kd->program, "Unsupported libelf");
184 		return (-1);
185 	}
186 	elf = elf_begin(kd->nlfd, ELF_C_READ, NULL);
187 	if (elf == NULL) {
188 		_kvm_err(kd, kd->program, "%s", elf_errmsg(0));
189 		return (-1);
190 	}
191 	if (elf_kind(elf) != ELF_K_ELF) {
192 		_kvm_err(kd, kd->program, "kernel is not an ELF file");
193 		return (-1);
194 	}
195 	if (gelf_getehdr(elf, &kd->nlehdr) == NULL) {
196 		_kvm_err(kd, kd->program, "%s", elf_errmsg(0));
197 		elf_end(elf);
198 		return (-1);
199 	}
200 	elf_end(elf);
201 
202 	switch (kd->nlehdr.e_ident[EI_DATA]) {
203 	case ELFDATA2LSB:
204 	case ELFDATA2MSB:
205 		return (0);
206 	default:
207 		_kvm_err(kd, kd->program,
208 		    "unsupported ELF data encoding for kernel");
209 		return (-1);
210 	}
211 }
212 
213 int
214 _kvm_probe_elf_kernel(kvm_t *kd, int class, int machine)
215 {
216 
217 	return (kd->nlehdr.e_ident[EI_CLASS] == class &&
218 	    kd->nlehdr.e_type == ET_EXEC &&
219 	    kd->nlehdr.e_machine == machine);
220 }
221 
222 int
223 _kvm_is_minidump(kvm_t *kd)
224 {
225 	char minihdr[8];
226 
227 	if (kd->rawdump)
228 		return (0);
229 	if (pread(kd->pmfd, &minihdr, 8, 0) == 8 &&
230 	    memcmp(&minihdr, "minidump", 8) == 0)
231 		return (1);
232 	return (0);
233 }
234 
235 /*
236  * The powerpc backend has a hack to strip a leading kerneldump
237  * header from the core before treating it as an ELF header.
238  *
239  * We can add that here if we can get a change to libelf to support
240  * an inital offset into the file.  Alternatively we could patch
241  * savecore to extract cores from a regular file instead.
242  */
243 int
244 _kvm_read_core_phdrs(kvm_t *kd, size_t *phnump, GElf_Phdr **phdrp)
245 {
246 	GElf_Ehdr ehdr;
247 	GElf_Phdr *phdr;
248 	Elf *elf;
249 	size_t i, phnum;
250 
251 	elf = elf_begin(kd->pmfd, ELF_C_READ, NULL);
252 	if (elf == NULL) {
253 		_kvm_err(kd, kd->program, "%s", elf_errmsg(0));
254 		return (-1);
255 	}
256 	if (elf_kind(elf) != ELF_K_ELF) {
257 		_kvm_err(kd, kd->program, "invalid core");
258 		goto bad;
259 	}
260 	if (gelf_getclass(elf) != kd->nlehdr.e_ident[EI_CLASS]) {
261 		_kvm_err(kd, kd->program, "invalid core");
262 		goto bad;
263 	}
264 	if (gelf_getehdr(elf, &ehdr) == NULL) {
265 		_kvm_err(kd, kd->program, "%s", elf_errmsg(0));
266 		goto bad;
267 	}
268 	if (ehdr.e_type != ET_CORE) {
269 		_kvm_err(kd, kd->program, "invalid core");
270 		goto bad;
271 	}
272 	if (ehdr.e_machine != kd->nlehdr.e_machine) {
273 		_kvm_err(kd, kd->program, "invalid core");
274 		goto bad;
275 	}
276 
277 	if (elf_getphdrnum(elf, &phnum) == -1) {
278 		_kvm_err(kd, kd->program, "%s", elf_errmsg(0));
279 		goto bad;
280 	}
281 
282 	phdr = calloc(phnum, sizeof(*phdr));
283 	if (phdr == NULL) {
284 		_kvm_err(kd, kd->program, "failed to allocate phdrs");
285 		goto bad;
286 	}
287 
288 	for (i = 0; i < phnum; i++) {
289 		if (gelf_getphdr(elf, i, &phdr[i]) == NULL) {
290 			_kvm_err(kd, kd->program, "%s", elf_errmsg(0));
291 			goto bad;
292 		}
293 	}
294 	elf_end(elf);
295 	*phnump = phnum;
296 	*phdrp = phdr;
297 	return (0);
298 
299 bad:
300 	elf_end(elf);
301 	return (-1);
302 }
303 
304 static void
305 _kvm_hpt_insert(struct hpt *hpt, uint64_t pa, off_t off)
306 {
307 	struct hpte *hpte;
308 	uint32_t fnv = FNV1_32_INIT;
309 
310 	fnv = fnv_32_buf(&pa, sizeof(pa), fnv);
311 	fnv &= (HPT_SIZE - 1);
312 	hpte = malloc(sizeof(*hpte));
313 	hpte->pa = pa;
314 	hpte->off = off;
315 	hpte->next = hpt->hpt_head[fnv];
316 	hpt->hpt_head[fnv] = hpte;
317 }
318 
319 void
320 _kvm_hpt_init(kvm_t *kd, struct hpt *hpt, void *base, size_t len, off_t off,
321     int page_size, int word_size)
322 {
323 	uint64_t bits, idx, pa;
324 	uint64_t *base64;
325 	uint32_t *base32;
326 
327 	base64 = base;
328 	base32 = base;
329 	for (idx = 0; idx < len / word_size; idx++) {
330 		if (word_size == sizeof(uint64_t))
331 			bits = _kvm64toh(kd, base64[idx]);
332 		else
333 			bits = _kvm32toh(kd, base32[idx]);
334 		pa = idx * word_size * NBBY * page_size;
335 		for (; bits != 0; bits >>= 1, pa += page_size) {
336 			if ((bits & 1) == 0)
337 				continue;
338 			_kvm_hpt_insert(hpt, pa, off);
339 			off += page_size;
340 		}
341 	}
342 }
343 
344 off_t
345 _kvm_hpt_find(struct hpt *hpt, uint64_t pa)
346 {
347 	struct hpte *hpte;
348 	uint32_t fnv = FNV1_32_INIT;
349 
350 	fnv = fnv_32_buf(&pa, sizeof(pa), fnv);
351 	fnv &= (HPT_SIZE - 1);
352 	for (hpte = hpt->hpt_head[fnv]; hpte != NULL; hpte = hpte->next) {
353 		if (pa == hpte->pa)
354 			return (hpte->off);
355 	}
356 	return (-1);
357 }
358 
359 void
360 _kvm_hpt_free(struct hpt *hpt)
361 {
362 	struct hpte *hpte, *next;
363 	int i;
364 
365 	for (i = 0; i < HPT_SIZE; i++) {
366 		for (hpte = hpt->hpt_head[i]; hpte != NULL; hpte = next) {
367 			next = hpte->next;
368 			free(hpte);
369 		}
370 	}
371 }
372 
373 static kvm_t *
374 _kvm_open(kvm_t *kd, const char *uf, const char *mf, int flag, char *errout)
375 {
376 	struct kvm_arch **parch;
377 	struct stat st;
378 
379 	kd->vmfd = -1;
380 	kd->pmfd = -1;
381 	kd->nlfd = -1;
382 	kd->vmst = 0;
383 	kd->procbase = 0;
384 	kd->argspc = 0;
385 	kd->argv = 0;
386 
387 	if (uf == 0)
388 		uf = getbootfile();
389 	else if (strlen(uf) >= MAXPATHLEN) {
390 		_kvm_err(kd, kd->program, "exec file name too long");
391 		goto failed;
392 	}
393 	if (flag & ~O_RDWR) {
394 		_kvm_err(kd, kd->program, "bad flags arg");
395 		goto failed;
396 	}
397 	if (mf == 0)
398 		mf = _PATH_MEM;
399 
400 	if ((kd->pmfd = open(mf, flag | O_CLOEXEC, 0)) < 0) {
401 		_kvm_syserr(kd, kd->program, "%s", mf);
402 		goto failed;
403 	}
404 	if (fstat(kd->pmfd, &st) < 0) {
405 		_kvm_syserr(kd, kd->program, "%s", mf);
406 		goto failed;
407 	}
408 	if (S_ISREG(st.st_mode) && st.st_size <= 0) {
409 		errno = EINVAL;
410 		_kvm_syserr(kd, kd->program, "empty file");
411 		goto failed;
412 	}
413 	if (S_ISCHR(st.st_mode)) {
414 		/*
415 		 * If this is a character special device, then check that
416 		 * it's /dev/mem.  If so, open kmem too.  (Maybe we should
417 		 * make it work for either /dev/mem or /dev/kmem -- in either
418 		 * case you're working with a live kernel.)
419 		 */
420 		if (strcmp(mf, _PATH_DEVNULL) == 0) {
421 			kd->vmfd = open(_PATH_DEVNULL, O_RDONLY | O_CLOEXEC);
422 			return (kd);
423 		} else if (strcmp(mf, _PATH_MEM) == 0) {
424 			if ((kd->vmfd = open(_PATH_KMEM, flag | O_CLOEXEC)) <
425 			    0) {
426 				_kvm_syserr(kd, kd->program, "%s", _PATH_KMEM);
427 				goto failed;
428 			}
429 			return (kd);
430 		}
431 	}
432 	/*
433 	 * This is a crash dump.
434 	 * Open the namelist fd and determine the architecture.
435 	 */
436 	if ((kd->nlfd = open(uf, O_RDONLY | O_CLOEXEC, 0)) < 0) {
437 		_kvm_syserr(kd, kd->program, "%s", uf);
438 		goto failed;
439 	}
440 	if (_kvm_read_kernel_ehdr(kd) < 0)
441 		goto failed;
442 	if (strncmp(mf, _PATH_FWMEM, strlen(_PATH_FWMEM)) == 0)
443 		kd->rawdump = 1;
444 	SET_FOREACH(parch, kvm_arch) {
445 		if ((*parch)->ka_probe(kd)) {
446 			kd->arch = *parch;
447 			break;
448 		}
449 	}
450 	if (kd->arch == NULL) {
451 		_kvm_err(kd, kd->program, "unsupported architecture");
452 		goto failed;
453 	}
454 
455 	/*
456 	 * Non-native kernels require a symbol resolver.
457 	 */
458 	if (!kd->arch->ka_native(kd) && kd->resolve_symbol == NULL) {
459 		_kvm_err(kd, kd->program,
460 		    "non-native kernel requires a symbol resolver");
461 		goto failed;
462 	}
463 
464 	/*
465 	 * Initialize the virtual address translation machinery.
466 	 */
467 	if (kd->arch->ka_initvtop(kd) < 0)
468 		goto failed;
469 	return (kd);
470 failed:
471 	/*
472 	 * Copy out the error if doing sane error semantics.
473 	 */
474 	if (errout != 0)
475 		strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX);
476 	(void)kvm_close(kd);
477 	return (0);
478 }
479 
480 kvm_t *
481 kvm_openfiles(const char *uf, const char *mf, const char *sf __unused, int flag,
482     char *errout)
483 {
484 	kvm_t *kd;
485 
486 	if ((kd = calloc(1, sizeof(*kd))) == NULL) {
487 		(void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX);
488 		return (0);
489 	}
490 	return (_kvm_open(kd, uf, mf, flag, errout));
491 }
492 
493 kvm_t *
494 kvm_open(const char *uf, const char *mf, const char *sf __unused, int flag,
495     const char *errstr)
496 {
497 	kvm_t *kd;
498 
499 	if ((kd = calloc(1, sizeof(*kd))) == NULL) {
500 		if (errstr != NULL)
501 			(void)fprintf(stderr, "%s: %s\n",
502 				      errstr, strerror(errno));
503 		return (0);
504 	}
505 	kd->program = errstr;
506 	return (_kvm_open(kd, uf, mf, flag, NULL));
507 }
508 
509 kvm_t *
510 kvm_open2(const char *uf, const char *mf, int flag, char *errout,
511     int (*resolver)(const char *, kvaddr_t *))
512 {
513 	kvm_t *kd;
514 
515 	if ((kd = calloc(1, sizeof(*kd))) == NULL) {
516 		(void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX);
517 		return (0);
518 	}
519 	kd->resolve_symbol = resolver;
520 	return (_kvm_open(kd, uf, mf, flag, errout));
521 }
522 
523 int
524 kvm_close(kvm_t *kd)
525 {
526 	int error = 0;
527 
528 	if (kd->vmst != NULL)
529 		kd->arch->ka_freevtop(kd);
530 	if (kd->pmfd >= 0)
531 		error |= close(kd->pmfd);
532 	if (kd->vmfd >= 0)
533 		error |= close(kd->vmfd);
534 	if (kd->nlfd >= 0)
535 		error |= close(kd->nlfd);
536 	if (kd->procbase != 0)
537 		free((void *)kd->procbase);
538 	if (kd->argbuf != 0)
539 		free((void *) kd->argbuf);
540 	if (kd->argspc != 0)
541 		free((void *) kd->argspc);
542 	if (kd->argv != 0)
543 		free((void *)kd->argv);
544 	free((void *)kd);
545 
546 	return (0);
547 }
548 
549 /*
550  * Walk the list of unresolved symbols, generate a new list and prefix the
551  * symbol names, try again, and merge back what we could resolve.
552  */
553 static int
554 kvm_fdnlist_prefix(kvm_t *kd, struct kvm_nlist *nl, int missing,
555     const char *prefix, kvaddr_t (*validate_fn)(kvm_t *, kvaddr_t))
556 {
557 	struct kvm_nlist *n, *np, *p;
558 	char *cp, *ce;
559 	const char *ccp;
560 	size_t len;
561 	int slen, unresolved;
562 
563 	/*
564 	 * Calculate the space we need to malloc for nlist and names.
565 	 * We are going to store the name twice for later lookups: once
566 	 * with the prefix and once the unmodified name delmited by \0.
567 	 */
568 	len = 0;
569 	unresolved = 0;
570 	for (p = nl; p->n_name && p->n_name[0]; ++p) {
571 		if (p->n_type != N_UNDF)
572 			continue;
573 		len += sizeof(struct kvm_nlist) + strlen(prefix) +
574 		    2 * (strlen(p->n_name) + 1);
575 		unresolved++;
576 	}
577 	if (unresolved == 0)
578 		return (unresolved);
579 	/* Add space for the terminating nlist entry. */
580 	len += sizeof(struct kvm_nlist);
581 	unresolved++;
582 
583 	/* Alloc one chunk for (nlist, [names]) and setup pointers. */
584 	n = np = malloc(len);
585 	bzero(n, len);
586 	if (n == NULL)
587 		return (missing);
588 	cp = ce = (char *)np;
589 	cp += unresolved * sizeof(struct kvm_nlist);
590 	ce += len;
591 
592 	/* Generate shortened nlist with special prefix. */
593 	unresolved = 0;
594 	for (p = nl; p->n_name && p->n_name[0]; ++p) {
595 		if (p->n_type != N_UNDF)
596 			continue;
597 		*np = *p;
598 		/* Save the new\0orig. name so we can later match it again. */
599 		slen = snprintf(cp, ce - cp, "%s%s%c%s", prefix,
600 		    (prefix[0] != '\0' && p->n_name[0] == '_') ?
601 			(p->n_name + 1) : p->n_name, '\0', p->n_name);
602 		if (slen < 0 || slen >= ce - cp)
603 			continue;
604 		np->n_name = cp;
605 		cp += slen + 1;
606 		np++;
607 		unresolved++;
608 	}
609 
610 	/* Do lookup on the reduced list. */
611 	np = n;
612 	unresolved = kvm_fdnlist(kd, np);
613 
614 	/* Check if we could resolve further symbols and update the list. */
615 	if (unresolved >= 0 && unresolved < missing) {
616 		/* Find the first freshly resolved entry. */
617 		for (; np->n_name && np->n_name[0]; np++)
618 			if (np->n_type != N_UNDF)
619 				break;
620 		/*
621 		 * The lists are both in the same order,
622 		 * so we can walk them in parallel.
623 		 */
624 		for (p = nl; np->n_name && np->n_name[0] &&
625 		    p->n_name && p->n_name[0]; ++p) {
626 			if (p->n_type != N_UNDF)
627 				continue;
628 			/* Skip expanded name and compare to orig. one. */
629 			ccp = np->n_name + strlen(np->n_name) + 1;
630 			if (strcmp(ccp, p->n_name) != 0)
631 				continue;
632 			/* Update nlist with new, translated results. */
633 			p->n_type = np->n_type;
634 			if (validate_fn)
635 				p->n_value = (*validate_fn)(kd, np->n_value);
636 			else
637 				p->n_value = np->n_value;
638 			missing--;
639 			/* Find next freshly resolved entry. */
640 			for (np++; np->n_name && np->n_name[0]; np++)
641 				if (np->n_type != N_UNDF)
642 					break;
643 		}
644 	}
645 	/* We could assert missing = unresolved here. */
646 
647 	free(n);
648 	return (unresolved);
649 }
650 
651 int
652 _kvm_nlist(kvm_t *kd, struct kvm_nlist *nl, int initialize)
653 {
654 	struct kvm_nlist *p;
655 	int nvalid;
656 	struct kld_sym_lookup lookup;
657 	int error;
658 	const char *prefix = "";
659 	char symname[1024]; /* XXX-BZ symbol name length limit? */
660 	int tried_vnet, tried_dpcpu;
661 
662 	/*
663 	 * If we can't use the kld symbol lookup, revert to the
664 	 * slow library call.
665 	 */
666 	if (!ISALIVE(kd)) {
667 		error = kvm_fdnlist(kd, nl);
668 		if (error <= 0)			/* Hard error or success. */
669 			return (error);
670 
671 		if (_kvm_vnet_initialized(kd, initialize))
672 			error = kvm_fdnlist_prefix(kd, nl, error,
673 			    VNET_SYMPREFIX, _kvm_vnet_validaddr);
674 
675 		if (error > 0 && _kvm_dpcpu_initialized(kd, initialize))
676 			error = kvm_fdnlist_prefix(kd, nl, error,
677 			    DPCPU_SYMPREFIX, _kvm_dpcpu_validaddr);
678 
679 		return (error);
680 	}
681 
682 	/*
683 	 * We can use the kld lookup syscall.  Go through each nlist entry
684 	 * and look it up with a kldsym(2) syscall.
685 	 */
686 	nvalid = 0;
687 	tried_vnet = 0;
688 	tried_dpcpu = 0;
689 again:
690 	for (p = nl; p->n_name && p->n_name[0]; ++p) {
691 		if (p->n_type != N_UNDF)
692 			continue;
693 
694 		lookup.version = sizeof(lookup);
695 		lookup.symvalue = 0;
696 		lookup.symsize = 0;
697 
698 		error = snprintf(symname, sizeof(symname), "%s%s", prefix,
699 		    (prefix[0] != '\0' && p->n_name[0] == '_') ?
700 			(p->n_name + 1) : p->n_name);
701 		if (error < 0 || error >= (int)sizeof(symname))
702 			continue;
703 		lookup.symname = symname;
704 		if (lookup.symname[0] == '_')
705 			lookup.symname++;
706 
707 		if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) {
708 			p->n_type = N_TEXT;
709 			if (_kvm_vnet_initialized(kd, initialize) &&
710 			    strcmp(prefix, VNET_SYMPREFIX) == 0)
711 				p->n_value =
712 				    _kvm_vnet_validaddr(kd, lookup.symvalue);
713 			else if (_kvm_dpcpu_initialized(kd, initialize) &&
714 			    strcmp(prefix, DPCPU_SYMPREFIX) == 0)
715 				p->n_value =
716 				    _kvm_dpcpu_validaddr(kd, lookup.symvalue);
717 			else
718 				p->n_value = lookup.symvalue;
719 			++nvalid;
720 			/* lookup.symsize */
721 		}
722 	}
723 
724 	/*
725 	 * Check the number of entries that weren't found. If they exist,
726 	 * try again with a prefix for virtualized or DPCPU symbol names.
727 	 */
728 	error = ((p - nl) - nvalid);
729 	if (error && _kvm_vnet_initialized(kd, initialize) && !tried_vnet) {
730 		tried_vnet = 1;
731 		prefix = VNET_SYMPREFIX;
732 		goto again;
733 	}
734 	if (error && _kvm_dpcpu_initialized(kd, initialize) && !tried_dpcpu) {
735 		tried_dpcpu = 1;
736 		prefix = DPCPU_SYMPREFIX;
737 		goto again;
738 	}
739 
740 	/*
741 	 * Return the number of entries that weren't found. If they exist,
742 	 * also fill internal error buffer.
743 	 */
744 	error = ((p - nl) - nvalid);
745 	if (error)
746 		_kvm_syserr(kd, kd->program, "kvm_nlist");
747 	return (error);
748 }
749 
750 int
751 kvm_nlist2(kvm_t *kd, struct kvm_nlist *nl)
752 {
753 
754 	/*
755 	 * If called via the public interface, permit intialization of
756 	 * further virtualized modules on demand.
757 	 */
758 	return (_kvm_nlist(kd, nl, 1));
759 }
760 
761 int
762 kvm_nlist(kvm_t *kd, struct nlist *nl)
763 {
764 	struct kvm_nlist *kl;
765 	int count, i, nfail;
766 
767 	/*
768 	 * Avoid reporting truncated addresses by failing for non-native
769 	 * cores.
770 	 */
771 	if (!kvm_native(kd)) {
772 		_kvm_err(kd, kd->program, "kvm_nlist of non-native vmcore");
773 		return (-1);
774 	}
775 
776 	for (count = 0; nl[count].n_name != NULL && nl[count].n_name[0] != '\0';
777 	     count++)
778 		;
779 	if (count == 0)
780 		return (0);
781 	kl = calloc(count + 1, sizeof(*kl));
782 	for (i = 0; i < count; i++)
783 		kl[i].n_name = nl[i].n_name;
784 	nfail = kvm_nlist2(kd, kl);
785 	for (i = 0; i < count; i++) {
786 		nl[i].n_type = kl[i].n_type;
787 		nl[i].n_other = 0;
788 		nl[i].n_desc = 0;
789 		nl[i].n_value = kl[i].n_value;
790 	}
791 	return (nfail);
792 }
793 
794 ssize_t
795 kvm_read(kvm_t *kd, u_long kva, void *buf, size_t len)
796 {
797 
798 	return (kvm_read2(kd, kva, buf, len));
799 }
800 
801 ssize_t
802 kvm_read2(kvm_t *kd, kvaddr_t kva, void *buf, size_t len)
803 {
804 	int cc;
805 	ssize_t cr;
806 	off_t pa;
807 	char *cp;
808 
809 	if (ISALIVE(kd)) {
810 		/*
811 		 * We're using /dev/kmem.  Just read straight from the
812 		 * device and let the active kernel do the address translation.
813 		 */
814 		errno = 0;
815 		if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
816 			_kvm_err(kd, 0, "invalid address (0x%jx)",
817 			    (uintmax_t)kva);
818 			return (-1);
819 		}
820 		cr = read(kd->vmfd, buf, len);
821 		if (cr < 0) {
822 			_kvm_syserr(kd, 0, "kvm_read");
823 			return (-1);
824 		} else if (cr < (ssize_t)len)
825 			_kvm_err(kd, kd->program, "short read");
826 		return (cr);
827 	}
828 
829 	cp = buf;
830 	while (len > 0) {
831 		cc = kd->arch->ka_kvatop(kd, kva, &pa);
832 		if (cc == 0)
833 			return (-1);
834 		if (cc > (ssize_t)len)
835 			cc = len;
836 		errno = 0;
837 		if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) {
838 			_kvm_syserr(kd, 0, _PATH_MEM);
839 			break;
840 		}
841 		cr = read(kd->pmfd, cp, cc);
842 		if (cr < 0) {
843 			_kvm_syserr(kd, kd->program, "kvm_read");
844 			break;
845 		}
846 		/*
847 		 * If ka_kvatop returns a bogus value or our core file is
848 		 * truncated, we might wind up seeking beyond the end of the
849 		 * core file in which case the read will return 0 (EOF).
850 		 */
851 		if (cr == 0)
852 			break;
853 		cp += cr;
854 		kva += cr;
855 		len -= cr;
856 	}
857 
858 	return (cp - (char *)buf);
859 }
860 
861 ssize_t
862 kvm_write(kvm_t *kd, u_long kva, const void *buf, size_t len)
863 {
864 	int cc;
865 
866 	if (ISALIVE(kd)) {
867 		/*
868 		 * Just like kvm_read, only we write.
869 		 */
870 		errno = 0;
871 		if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) {
872 			_kvm_err(kd, 0, "invalid address (%lx)", kva);
873 			return (-1);
874 		}
875 		cc = write(kd->vmfd, buf, len);
876 		if (cc < 0) {
877 			_kvm_syserr(kd, 0, "kvm_write");
878 			return (-1);
879 		} else if ((size_t)cc < len)
880 			_kvm_err(kd, kd->program, "short write");
881 		return (cc);
882 	} else {
883 		_kvm_err(kd, kd->program,
884 		    "kvm_write not implemented for dead kernels");
885 		return (-1);
886 	}
887 	/* NOTREACHED */
888 }
889 
890 int
891 kvm_native(kvm_t *kd)
892 {
893 
894 	if (ISALIVE(kd))
895 		return (1);
896 	return (kd->arch->ka_native(kd));
897 }
898