kvm.c revision 217744
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: head/lib/libkvm/kvm.c 217744 2011-01-23 11:08:28Z uqs $"); 36 37#if defined(LIBC_SCCS) && !defined(lint) 38#if 0 39static 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 45#define _WANT_VNET 46 47#include <sys/user.h> 48#include <sys/proc.h> 49#include <sys/ioctl.h> 50#include <sys/stat.h> 51#include <sys/sysctl.h> 52#include <sys/linker.h> 53#include <sys/pcpu.h> 54 55#include <net/vnet.h> 56 57#include <vm/vm.h> 58#include <vm/vm_param.h> 59 60#include <machine/vmparam.h> 61 62#include <ctype.h> 63#include <fcntl.h> 64#include <kvm.h> 65#include <limits.h> 66#include <nlist.h> 67#include <paths.h> 68#include <stdio.h> 69#include <stdlib.h> 70#include <string.h> 71#include <strings.h> 72#include <unistd.h> 73 74#include "kvm_private.h" 75 76/* from src/lib/libc/gen/nlist.c */ 77int __fdnlist(int, struct nlist *); 78 79char * 80kvm_geterr(kvm_t *kd) 81{ 82 return (kd->errbuf); 83} 84 85#include <stdarg.h> 86 87/* 88 * Report an error using printf style arguments. "program" is kd->program 89 * on hard errors, and 0 on soft errors, so that under sun error emulation, 90 * only hard errors are printed out (otherwise, programs like gdb will 91 * generate tons of error messages when trying to access bogus pointers). 92 */ 93void 94_kvm_err(kvm_t *kd, const char *program, const char *fmt, ...) 95{ 96 va_list ap; 97 98 va_start(ap, fmt); 99 if (program != NULL) { 100 (void)fprintf(stderr, "%s: ", program); 101 (void)vfprintf(stderr, fmt, ap); 102 (void)fputc('\n', stderr); 103 } else 104 (void)vsnprintf(kd->errbuf, 105 sizeof(kd->errbuf), fmt, ap); 106 107 va_end(ap); 108} 109 110void 111_kvm_syserr(kvm_t *kd, const char *program, const char *fmt, ...) 112{ 113 va_list ap; 114 int n; 115 116 va_start(ap, fmt); 117 if (program != NULL) { 118 (void)fprintf(stderr, "%s: ", program); 119 (void)vfprintf(stderr, fmt, ap); 120 (void)fprintf(stderr, ": %s\n", strerror(errno)); 121 } else { 122 char *cp = kd->errbuf; 123 124 (void)vsnprintf(cp, sizeof(kd->errbuf), fmt, ap); 125 n = strlen(cp); 126 (void)snprintf(&cp[n], sizeof(kd->errbuf) - n, ": %s", 127 strerror(errno)); 128 } 129 va_end(ap); 130} 131 132void * 133_kvm_malloc(kvm_t *kd, size_t n) 134{ 135 void *p; 136 137 if ((p = calloc(n, sizeof(char))) == NULL) 138 _kvm_err(kd, kd->program, "can't allocate %zu bytes: %s", 139 n, strerror(errno)); 140 return (p); 141} 142 143static kvm_t * 144_kvm_open(kvm_t *kd, const char *uf, const char *mf, int flag, char *errout) 145{ 146 struct stat st; 147 148 kd->vmfd = -1; 149 kd->pmfd = -1; 150 kd->nlfd = -1; 151 kd->vmst = 0; 152 kd->procbase = 0; 153 kd->argspc = 0; 154 kd->argv = 0; 155 156 if (uf == 0) 157 uf = getbootfile(); 158 else if (strlen(uf) >= MAXPATHLEN) { 159 _kvm_err(kd, kd->program, "exec file name too long"); 160 goto failed; 161 } 162 if (flag & ~O_RDWR) { 163 _kvm_err(kd, kd->program, "bad flags arg"); 164 goto failed; 165 } 166 if (mf == 0) 167 mf = _PATH_MEM; 168 169 if ((kd->pmfd = open(mf, flag, 0)) < 0) { 170 _kvm_syserr(kd, kd->program, "%s", mf); 171 goto failed; 172 } 173 if (fstat(kd->pmfd, &st) < 0) { 174 _kvm_syserr(kd, kd->program, "%s", mf); 175 goto failed; 176 } 177 if (S_ISREG(st.st_mode) && st.st_size <= 0) { 178 errno = EINVAL; 179 _kvm_syserr(kd, kd->program, "empty file"); 180 goto failed; 181 } 182 if (fcntl(kd->pmfd, F_SETFD, FD_CLOEXEC) < 0) { 183 _kvm_syserr(kd, kd->program, "%s", mf); 184 goto failed; 185 } 186 if (S_ISCHR(st.st_mode)) { 187 /* 188 * If this is a character special device, then check that 189 * it's /dev/mem. If so, open kmem too. (Maybe we should 190 * make it work for either /dev/mem or /dev/kmem -- in either 191 * case you're working with a live kernel.) 192 */ 193 if (strcmp(mf, _PATH_DEVNULL) == 0) { 194 kd->vmfd = open(_PATH_DEVNULL, O_RDONLY); 195 return (kd); 196 } else if (strcmp(mf, _PATH_MEM) == 0) { 197 if ((kd->vmfd = open(_PATH_KMEM, flag)) < 0) { 198 _kvm_syserr(kd, kd->program, "%s", _PATH_KMEM); 199 goto failed; 200 } 201 if (fcntl(kd->vmfd, F_SETFD, FD_CLOEXEC) < 0) { 202 _kvm_syserr(kd, kd->program, "%s", _PATH_KMEM); 203 goto failed; 204 } 205 return (kd); 206 } 207 } 208 /* 209 * This is a crash dump. 210 * Initialize the virtual address translation machinery, 211 * but first setup the namelist fd. 212 */ 213 if ((kd->nlfd = open(uf, O_RDONLY, 0)) < 0) { 214 _kvm_syserr(kd, kd->program, "%s", uf); 215 goto failed; 216 } 217 if (fcntl(kd->nlfd, F_SETFD, FD_CLOEXEC) < 0) { 218 _kvm_syserr(kd, kd->program, "%s", uf); 219 goto failed; 220 } 221 if (strncmp(mf, _PATH_FWMEM, strlen(_PATH_FWMEM)) == 0) 222 kd->rawdump = 1; 223 if (_kvm_initvtop(kd) < 0) 224 goto failed; 225 return (kd); 226failed: 227 /* 228 * Copy out the error if doing sane error semantics. 229 */ 230 if (errout != 0) 231 strlcpy(errout, kd->errbuf, _POSIX2_LINE_MAX); 232 (void)kvm_close(kd); 233 return (0); 234} 235 236kvm_t * 237kvm_openfiles(const char *uf, const char *mf, const char *sf __unused, int flag, 238 char *errout) 239{ 240 kvm_t *kd; 241 242 if ((kd = calloc(1, sizeof(*kd))) == NULL) { 243 (void)strlcpy(errout, strerror(errno), _POSIX2_LINE_MAX); 244 return (0); 245 } 246 kd->program = 0; 247 return (_kvm_open(kd, uf, mf, flag, errout)); 248} 249 250kvm_t * 251kvm_open(const char *uf, const char *mf, const char *sf __unused, int flag, 252 const char *errstr) 253{ 254 kvm_t *kd; 255 256 if ((kd = calloc(1, sizeof(*kd))) == NULL) { 257 if (errstr != NULL) 258 (void)fprintf(stderr, "%s: %s\n", 259 errstr, strerror(errno)); 260 return (0); 261 } 262 kd->program = errstr; 263 return (_kvm_open(kd, uf, mf, flag, NULL)); 264} 265 266int 267kvm_close(kvm_t *kd) 268{ 269 int error = 0; 270 271 if (kd->pmfd >= 0) 272 error |= close(kd->pmfd); 273 if (kd->vmfd >= 0) 274 error |= close(kd->vmfd); 275 if (kd->nlfd >= 0) 276 error |= close(kd->nlfd); 277 if (kd->vmst) 278 _kvm_freevtop(kd); 279 if (kd->procbase != 0) 280 free((void *)kd->procbase); 281 if (kd->argbuf != 0) 282 free((void *) kd->argbuf); 283 if (kd->argspc != 0) 284 free((void *) kd->argspc); 285 if (kd->argv != 0) 286 free((void *)kd->argv); 287 free((void *)kd); 288 289 return (0); 290} 291 292/* 293 * Walk the list of unresolved symbols, generate a new list and prefix the 294 * symbol names, try again, and merge back what we could resolve. 295 */ 296static int 297kvm_fdnlist_prefix(kvm_t *kd, struct nlist *nl, int missing, const char *prefix, 298 uintptr_t (*validate_fn)(kvm_t *, uintptr_t)) 299{ 300 struct nlist *n, *np, *p; 301 char *cp, *ce; 302 const char *ccp; 303 size_t len; 304 int slen, unresolved; 305 306 /* 307 * Calculate the space we need to malloc for nlist and names. 308 * We are going to store the name twice for later lookups: once 309 * with the prefix and once the unmodified name delmited by \0. 310 */ 311 len = 0; 312 unresolved = 0; 313 for (p = nl; p->n_name && p->n_name[0]; ++p) { 314 if (p->n_type != N_UNDF) 315 continue; 316 len += sizeof(struct nlist) + strlen(prefix) + 317 2 * (strlen(p->n_name) + 1); 318 unresolved++; 319 } 320 if (unresolved == 0) 321 return (unresolved); 322 /* Add space for the terminating nlist entry. */ 323 len += sizeof(struct nlist); 324 unresolved++; 325 326 /* Alloc one chunk for (nlist, [names]) and setup pointers. */ 327 n = np = malloc(len); 328 bzero(n, len); 329 if (n == NULL) 330 return (missing); 331 cp = ce = (char *)np; 332 cp += unresolved * sizeof(struct nlist); 333 ce += len; 334 335 /* Generate shortened nlist with special prefix. */ 336 unresolved = 0; 337 for (p = nl; p->n_name && p->n_name[0]; ++p) { 338 if (p->n_type != N_UNDF) 339 continue; 340 bcopy(p, np, sizeof(struct nlist)); 341 /* Save the new\0orig. name so we can later match it again. */ 342 slen = snprintf(cp, ce - cp, "%s%s%c%s", prefix, 343 (prefix[0] != '\0' && p->n_name[0] == '_') ? 344 (p->n_name + 1) : p->n_name, '\0', p->n_name); 345 if (slen < 0 || slen >= ce - cp) 346 continue; 347 np->n_name = cp; 348 cp += slen + 1; 349 np++; 350 unresolved++; 351 } 352 353 /* Do lookup on the reduced list. */ 354 np = n; 355 unresolved = __fdnlist(kd->nlfd, np); 356 357 /* Check if we could resolve further symbols and update the list. */ 358 if (unresolved >= 0 && unresolved < missing) { 359 /* Find the first freshly resolved entry. */ 360 for (; np->n_name && np->n_name[0]; np++) 361 if (np->n_type != N_UNDF) 362 break; 363 /* 364 * The lists are both in the same order, 365 * so we can walk them in parallel. 366 */ 367 for (p = nl; np->n_name && np->n_name[0] && 368 p->n_name && p->n_name[0]; ++p) { 369 if (p->n_type != N_UNDF) 370 continue; 371 /* Skip expanded name and compare to orig. one. */ 372 ccp = np->n_name + strlen(np->n_name) + 1; 373 if (strcmp(ccp, p->n_name) != 0) 374 continue; 375 /* Update nlist with new, translated results. */ 376 p->n_type = np->n_type; 377 p->n_other = np->n_other; 378 p->n_desc = np->n_desc; 379 if (validate_fn) 380 p->n_value = (*validate_fn)(kd, np->n_value); 381 else 382 p->n_value = np->n_value; 383 missing--; 384 /* Find next freshly resolved entry. */ 385 for (np++; np->n_name && np->n_name[0]; np++) 386 if (np->n_type != N_UNDF) 387 break; 388 } 389 } 390 /* We could assert missing = unresolved here. */ 391 392 free(n); 393 return (unresolved); 394} 395 396int 397_kvm_nlist(kvm_t *kd, struct nlist *nl, int initialize) 398{ 399 struct nlist *p; 400 int nvalid; 401 struct kld_sym_lookup lookup; 402 int error; 403 const char *prefix = ""; 404 char symname[1024]; /* XXX-BZ symbol name length limit? */ 405 int tried_vnet, tried_dpcpu; 406 407 /* 408 * If we can't use the kld symbol lookup, revert to the 409 * slow library call. 410 */ 411 if (!ISALIVE(kd)) { 412 error = __fdnlist(kd->nlfd, nl); 413 if (error <= 0) /* Hard error or success. */ 414 return (error); 415 416 if (_kvm_vnet_initialized(kd, initialize)) 417 error = kvm_fdnlist_prefix(kd, nl, error, 418 VNET_SYMPREFIX, _kvm_vnet_validaddr); 419 420 if (error > 0 && _kvm_dpcpu_initialized(kd, initialize)) 421 error = kvm_fdnlist_prefix(kd, nl, error, 422 DPCPU_SYMPREFIX, _kvm_dpcpu_validaddr); 423 424 return (error); 425 } 426 427 /* 428 * We can use the kld lookup syscall. Go through each nlist entry 429 * and look it up with a kldsym(2) syscall. 430 */ 431 nvalid = 0; 432 tried_vnet = 0; 433 tried_dpcpu = 0; 434again: 435 for (p = nl; p->n_name && p->n_name[0]; ++p) { 436 if (p->n_type != N_UNDF) 437 continue; 438 439 lookup.version = sizeof(lookup); 440 lookup.symvalue = 0; 441 lookup.symsize = 0; 442 443 error = snprintf(symname, sizeof(symname), "%s%s", prefix, 444 (prefix[0] != '\0' && p->n_name[0] == '_') ? 445 (p->n_name + 1) : p->n_name); 446 if (error < 0 || error >= (int)sizeof(symname)) 447 continue; 448 lookup.symname = symname; 449 if (lookup.symname[0] == '_') 450 lookup.symname++; 451 452 if (kldsym(0, KLDSYM_LOOKUP, &lookup) != -1) { 453 p->n_type = N_TEXT; 454 p->n_other = 0; 455 p->n_desc = 0; 456 if (_kvm_vnet_initialized(kd, initialize) && 457 !strcmp(prefix, VNET_SYMPREFIX) == 0) 458 p->n_value = 459 _kvm_vnet_validaddr(kd, lookup.symvalue); 460 else if (_kvm_dpcpu_initialized(kd, initialize) && 461 !strcmp(prefix, DPCPU_SYMPREFIX) == 0) 462 p->n_value = 463 _kvm_dpcpu_validaddr(kd, lookup.symvalue); 464 else 465 p->n_value = lookup.symvalue; 466 ++nvalid; 467 /* lookup.symsize */ 468 } 469 } 470 471 /* 472 * Check the number of entries that weren't found. If they exist, 473 * try again with a prefix for virtualized or DPCPU symbol names. 474 */ 475 error = ((p - nl) - nvalid); 476 if (error && _kvm_vnet_initialized(kd, initialize) && !tried_vnet) { 477 tried_vnet = 1; 478 prefix = VNET_SYMPREFIX; 479 goto again; 480 } 481 if (error && _kvm_dpcpu_initialized(kd, initialize) && !tried_dpcpu) { 482 tried_dpcpu = 1; 483 prefix = DPCPU_SYMPREFIX; 484 goto again; 485 } 486 487 /* 488 * Return the number of entries that weren't found. If they exist, 489 * also fill internal error buffer. 490 */ 491 error = ((p - nl) - nvalid); 492 if (error) 493 _kvm_syserr(kd, kd->program, "kvm_nlist"); 494 return (error); 495} 496 497int 498kvm_nlist(kvm_t *kd, struct nlist *nl) 499{ 500 501 /* 502 * If called via the public interface, permit intialization of 503 * further virtualized modules on demand. 504 */ 505 return (_kvm_nlist(kd, nl, 1)); 506} 507 508ssize_t 509kvm_read(kvm_t *kd, u_long kva, void *buf, size_t len) 510{ 511 int cc; 512 ssize_t cr; 513 off_t pa; 514 char *cp; 515 516 if (ISALIVE(kd)) { 517 /* 518 * We're using /dev/kmem. Just read straight from the 519 * device and let the active kernel do the address translation. 520 */ 521 errno = 0; 522 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) { 523 _kvm_err(kd, 0, "invalid address (%lx)", kva); 524 return (-1); 525 } 526 cr = read(kd->vmfd, buf, len); 527 if (cr < 0) { 528 _kvm_syserr(kd, 0, "kvm_read"); 529 return (-1); 530 } else if (cr < (ssize_t)len) 531 _kvm_err(kd, kd->program, "short read"); 532 return (cr); 533 } 534 535 cp = buf; 536 while (len > 0) { 537 cc = _kvm_kvatop(kd, kva, &pa); 538 if (cc == 0) 539 return (-1); 540 if (cc > (ssize_t)len) 541 cc = len; 542 errno = 0; 543 if (lseek(kd->pmfd, pa, 0) == -1 && errno != 0) { 544 _kvm_syserr(kd, 0, _PATH_MEM); 545 break; 546 } 547 cr = read(kd->pmfd, cp, cc); 548 if (cr < 0) { 549 _kvm_syserr(kd, kd->program, "kvm_read"); 550 break; 551 } 552 /* 553 * If kvm_kvatop returns a bogus value or our core file is 554 * truncated, we might wind up seeking beyond the end of the 555 * core file in which case the read will return 0 (EOF). 556 */ 557 if (cr == 0) 558 break; 559 cp += cr; 560 kva += cr; 561 len -= cr; 562 } 563 564 return (cp - (char *)buf); 565} 566 567ssize_t 568kvm_write(kvm_t *kd, u_long kva, const void *buf, size_t len) 569{ 570 int cc; 571 572 if (ISALIVE(kd)) { 573 /* 574 * Just like kvm_read, only we write. 575 */ 576 errno = 0; 577 if (lseek(kd->vmfd, (off_t)kva, 0) == -1 && errno != 0) { 578 _kvm_err(kd, 0, "invalid address (%lx)", kva); 579 return (-1); 580 } 581 cc = write(kd->vmfd, buf, len); 582 if (cc < 0) { 583 _kvm_syserr(kd, 0, "kvm_write"); 584 return (-1); 585 } else if ((size_t)cc < len) 586 _kvm_err(kd, kd->program, "short write"); 587 return (cc); 588 } else { 589 _kvm_err(kd, kd->program, 590 "kvm_write not implemented for dead kernels"); 591 return (-1); 592 } 593 /* NOTREACHED */ 594} 595