link_elf.c revision 105434
1/*- 2 * Copyright (c) 1998-2000 Doug Rabson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: head/sys/kern/link_elf.c 105434 2002-10-19 05:01:54Z marcel $ 27 */ 28 29#include "opt_ddb.h" 30 31#include <sys/param.h> 32#include <sys/systm.h> 33#include <sys/kernel.h> 34#include <sys/lock.h> 35#include <sys/malloc.h> 36#include <sys/mutex.h> 37#include <sys/proc.h> 38#include <sys/namei.h> 39#include <sys/fcntl.h> 40#include <sys/vnode.h> 41#include <sys/linker.h> 42 43#include <machine/elf.h> 44#ifdef GPROF 45#include <machine/profile.h> 46#endif 47 48#include <vm/vm.h> 49#include <vm/vm_param.h> 50#ifdef SPARSE_MAPPING 51#include <vm/vm_object.h> 52#include <vm/vm_kern.h> 53#include <vm/vm_extern.h> 54#endif 55#include <vm/pmap.h> 56#include <vm/vm_map.h> 57 58#include <sys/link_elf.h> 59 60#include "linker_if.h" 61 62typedef struct elf_file { 63 struct linker_file lf; /* Common fields */ 64 int preloaded; /* Was file pre-loaded */ 65 caddr_t address; /* Relocation address */ 66#ifdef SPARSE_MAPPING 67 vm_object_t object; /* VM object to hold file pages */ 68#endif 69 Elf_Dyn* dynamic; /* Symbol table etc. */ 70 Elf_Hashelt nbuckets; /* DT_HASH info */ 71 Elf_Hashelt nchains; 72 const Elf_Hashelt* buckets; 73 const Elf_Hashelt* chains; 74 caddr_t hash; 75 caddr_t strtab; /* DT_STRTAB */ 76 int strsz; /* DT_STRSZ */ 77 const Elf_Sym* symtab; /* DT_SYMTAB */ 78 Elf_Addr* got; /* DT_PLTGOT */ 79 const Elf_Rel* pltrel; /* DT_JMPREL */ 80 int pltrelsize; /* DT_PLTRELSZ */ 81 const Elf_Rela* pltrela; /* DT_JMPREL */ 82 int pltrelasize; /* DT_PLTRELSZ */ 83 const Elf_Rel* rel; /* DT_REL */ 84 int relsize; /* DT_RELSZ */ 85 const Elf_Rela* rela; /* DT_RELA */ 86 int relasize; /* DT_RELASZ */ 87 caddr_t modptr; 88 const Elf_Sym* ddbsymtab; /* The symbol table we are using */ 89 long ddbsymcnt; /* Number of symbols */ 90 caddr_t ddbstrtab; /* String table */ 91 long ddbstrcnt; /* number of bytes in string table */ 92 caddr_t symbase; /* malloc'ed symbold base */ 93 caddr_t strbase; /* malloc'ed string base */ 94#ifdef DDB 95 struct link_map gdb; /* hooks for gdb */ 96#endif 97} *elf_file_t; 98 99static int link_elf_link_preload(linker_class_t cls, 100 const char*, linker_file_t*); 101static int link_elf_link_preload_finish(linker_file_t); 102static int link_elf_load_file(linker_class_t, const char*, linker_file_t*); 103static int link_elf_lookup_symbol(linker_file_t, const char*, 104 c_linker_sym_t*); 105static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*); 106static int link_elf_search_symbol(linker_file_t, caddr_t value, 107 c_linker_sym_t* sym, long* diffp); 108 109static void link_elf_unload_file(linker_file_t); 110static void link_elf_unload_preload(linker_file_t); 111static int link_elf_lookup_set(linker_file_t, const char *, 112 void ***, void ***, int *); 113static int link_elf_each_function_name(linker_file_t, 114 int (*)(const char *, void *), 115 void *); 116 117static kobj_method_t link_elf_methods[] = { 118 KOBJMETHOD(linker_lookup_symbol, link_elf_lookup_symbol), 119 KOBJMETHOD(linker_symbol_values, link_elf_symbol_values), 120 KOBJMETHOD(linker_search_symbol, link_elf_search_symbol), 121 KOBJMETHOD(linker_unload, link_elf_unload_file), 122 KOBJMETHOD(linker_load_file, link_elf_load_file), 123 KOBJMETHOD(linker_link_preload, link_elf_link_preload), 124 KOBJMETHOD(linker_link_preload_finish, link_elf_link_preload_finish), 125 KOBJMETHOD(linker_lookup_set, link_elf_lookup_set), 126 KOBJMETHOD(linker_each_function_name, link_elf_each_function_name), 127 { 0, 0 } 128}; 129 130static struct linker_class link_elf_class = { 131#if ELF_TARG_CLASS == ELFCLASS32 132 "elf32", 133#else 134 "elf64", 135#endif 136 link_elf_methods, sizeof(struct elf_file) 137}; 138 139static int parse_dynamic(elf_file_t ef); 140static int relocate_file(elf_file_t ef); 141static int link_elf_preload_parse_symbols(elf_file_t ef); 142 143#ifdef DDB 144static void r_debug_state(struct r_debug *dummy_one, 145 struct link_map *dummy_two); 146 147/* 148 * A list of loaded modules for GDB to use for loading symbols. 149 */ 150struct r_debug r_debug; 151 152#define GDB_STATE(s) r_debug.r_state = s; r_debug_state(NULL, NULL); 153 154/* 155 * Function for the debugger to set a breakpoint on to gain control. 156 */ 157static void 158r_debug_state(struct r_debug *dummy_one __unused, 159 struct link_map *dummy_two __unused) 160{ 161} 162 163#endif 164 165#ifdef __ia64__ 166Elf_Addr link_elf_get_gp(linker_file_t); 167#endif 168 169/* 170 * The kernel symbol table starts here. 171 */ 172extern struct _dynamic _DYNAMIC; 173 174static void 175link_elf_init(void* arg) 176{ 177 Elf_Dyn *dp; 178 caddr_t modptr, baseptr, sizeptr; 179 elf_file_t ef; 180 char *modname; 181#ifdef DDB 182 char *newfilename; 183#endif 184 185 linker_add_class(&link_elf_class); 186 187 dp = (Elf_Dyn*) &_DYNAMIC; 188 modname = NULL; 189 modptr = preload_search_by_type("elf kernel"); 190 if (modptr) 191 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 192 if (modname == NULL) 193 modname = "kernel"; 194 linker_kernel_file = linker_make_file(modname, &link_elf_class); 195 if (linker_kernel_file == NULL) 196 panic("link_elf_init: Can't create linker structures for kernel"); 197 198 ef = (elf_file_t) linker_kernel_file; 199 ef->preloaded = 1; 200 ef->address = 0; 201#ifdef SPARSE_MAPPING 202 ef->object = 0; 203#endif 204 ef->dynamic = dp; 205 206 if (dp) 207 parse_dynamic(ef); 208 linker_kernel_file->address = (caddr_t) KERNBASE; 209 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address; 210 211 if (modptr) { 212 ef->modptr = modptr; 213 baseptr = preload_search_info(modptr, MODINFO_ADDR); 214 if (baseptr) 215 linker_kernel_file->address = *(caddr_t *)baseptr; 216 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 217 if (sizeptr) 218 linker_kernel_file->size = *(size_t *)sizeptr; 219 } 220 (void)link_elf_preload_parse_symbols(ef); 221 222#ifdef DDB 223 ef->gdb.l_addr = linker_kernel_file->address; 224 newfilename = malloc(strlen(modname) + 1, M_LINKER, M_WAITOK); 225 strcpy(newfilename, modname); 226 ef->gdb.l_name = newfilename; 227 ef->gdb.l_ld = dp; 228 ef->gdb.l_prev = 0; 229 ef->gdb.l_next = 0; 230 231 r_debug.r_map = &ef->gdb; 232 r_debug.r_brk = r_debug_state; 233 r_debug.r_state = RT_CONSISTENT; 234 235 r_debug_state(NULL, NULL); /* say hello to gdb! */ 236#endif 237} 238 239SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0); 240 241static int 242link_elf_preload_parse_symbols(elf_file_t ef) 243{ 244 caddr_t pointer; 245 caddr_t ssym, esym, base; 246 caddr_t strtab; 247 int strcnt; 248 Elf_Sym* symtab; 249 int symcnt; 250 251 if (ef->modptr == NULL) 252 return 0; 253 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 254 if (pointer == NULL) 255 return 0; 256 ssym = *(caddr_t *)pointer; 257 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 258 if (pointer == NULL) 259 return 0; 260 esym = *(caddr_t *)pointer; 261 262 base = ssym; 263 264 symcnt = *(long *)base; 265 base += sizeof(long); 266 symtab = (Elf_Sym *)base; 267 base += roundup(symcnt, sizeof(long)); 268 269 if (base > esym || base < ssym) { 270 printf("Symbols are corrupt!\n"); 271 return EINVAL; 272 } 273 274 strcnt = *(long *)base; 275 base += sizeof(long); 276 strtab = base; 277 base += roundup(strcnt, sizeof(long)); 278 279 if (base > esym || base < ssym) { 280 printf("Symbols are corrupt!\n"); 281 return EINVAL; 282 } 283 284 ef->ddbsymtab = symtab; 285 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 286 ef->ddbstrtab = strtab; 287 ef->ddbstrcnt = strcnt; 288 289 return 0; 290} 291 292static int 293parse_dynamic(elf_file_t ef) 294{ 295 Elf_Dyn *dp; 296 int plttype = DT_REL; 297 298 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 299 switch (dp->d_tag) { 300 case DT_HASH: 301 { 302 /* From src/libexec/rtld-elf/rtld.c */ 303 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 304 (ef->address + dp->d_un.d_ptr); 305 ef->nbuckets = hashtab[0]; 306 ef->nchains = hashtab[1]; 307 ef->buckets = hashtab + 2; 308 ef->chains = ef->buckets + ef->nbuckets; 309 break; 310 } 311 case DT_STRTAB: 312 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 313 break; 314 case DT_STRSZ: 315 ef->strsz = dp->d_un.d_val; 316 break; 317 case DT_SYMTAB: 318 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 319 break; 320 case DT_SYMENT: 321 if (dp->d_un.d_val != sizeof(Elf_Sym)) 322 return ENOEXEC; 323 break; 324 case DT_PLTGOT: 325 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 326 break; 327 case DT_REL: 328 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 329 break; 330 case DT_RELSZ: 331 ef->relsize = dp->d_un.d_val; 332 break; 333 case DT_RELENT: 334 if (dp->d_un.d_val != sizeof(Elf_Rel)) 335 return ENOEXEC; 336 break; 337 case DT_JMPREL: 338 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 339 break; 340 case DT_PLTRELSZ: 341 ef->pltrelsize = dp->d_un.d_val; 342 break; 343 case DT_RELA: 344 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 345 break; 346 case DT_RELASZ: 347 ef->relasize = dp->d_un.d_val; 348 break; 349 case DT_RELAENT: 350 if (dp->d_un.d_val != sizeof(Elf_Rela)) 351 return ENOEXEC; 352 break; 353 case DT_PLTREL: 354 plttype = dp->d_un.d_val; 355 if (plttype != DT_REL && plttype != DT_RELA) 356 return ENOEXEC; 357 break; 358#ifdef DDB 359 case DT_DEBUG: 360 dp->d_un.d_ptr = (Elf_Addr) &r_debug; 361 break; 362#endif 363 } 364 } 365 366 if (plttype == DT_RELA) { 367 ef->pltrela = (const Elf_Rela *) ef->pltrel; 368 ef->pltrel = NULL; 369 ef->pltrelasize = ef->pltrelsize; 370 ef->pltrelsize = 0; 371 } 372 373 ef->ddbsymtab = ef->symtab; 374 ef->ddbsymcnt = ef->nchains; 375 ef->ddbstrtab = ef->strtab; 376 ef->ddbstrcnt = ef->strsz; 377 378 return 0; 379} 380 381static void 382link_elf_error(const char *s) 383{ 384 printf("kldload: %s\n", s); 385} 386 387#ifdef DDB 388 389static void 390link_elf_add_gdb(struct link_map *l) 391{ 392 struct link_map *prev; 393 394 /* 395 * Scan to the end of the list. 396 */ 397 for (prev = r_debug.r_map; prev->l_next != NULL; prev = prev->l_next) 398 ; 399 400 /* Link in the new entry. */ 401 l->l_prev = prev; 402 l->l_next = prev->l_next; 403 prev->l_next = l; 404} 405 406static void 407link_elf_delete_gdb(struct link_map *l) 408{ 409 if (l->l_prev == NULL) { 410 if ((r_debug.r_map = l->l_next) != NULL) 411 l->l_next->l_prev = NULL; 412 return; 413 } 414 415 if ((l->l_prev->l_next = l->l_next) != NULL) 416 l->l_next->l_prev = l->l_prev; 417} 418 419#endif /* DDB */ 420 421static int 422link_elf_link_preload(linker_class_t cls, 423 const char* filename, linker_file_t *result) 424{ 425 caddr_t modptr, baseptr, sizeptr, dynptr; 426 char *type; 427 elf_file_t ef; 428 linker_file_t lf; 429 int error; 430 vm_offset_t dp; 431 432 /* Look to see if we have the file preloaded */ 433 modptr = preload_search_by_name(filename); 434 if (modptr == NULL) 435 return ENOENT; 436 437 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 438 baseptr = preload_search_info(modptr, MODINFO_ADDR); 439 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 440 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 441 if (type == NULL || strcmp(type, "elf module") != 0) 442 return (EFTYPE); 443 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 444 return (EINVAL); 445 446 lf = linker_make_file(filename, &link_elf_class); 447 if (lf == NULL) { 448 return ENOMEM; 449 } 450 451 ef = (elf_file_t) lf; 452 ef->preloaded = 1; 453 ef->modptr = modptr; 454 ef->address = *(caddr_t *)baseptr; 455#ifdef SPARSE_MAPPING 456 ef->object = 0; 457#endif 458 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 459 ef->dynamic = (Elf_Dyn *)dp; 460 lf->address = ef->address; 461 lf->size = *(size_t *)sizeptr; 462 463 error = parse_dynamic(ef); 464 if (error) { 465 linker_file_unload(lf); 466 return error; 467 } 468 *result = lf; 469 return (0); 470} 471 472static int 473link_elf_link_preload_finish(linker_file_t lf) 474{ 475 elf_file_t ef; 476 int error; 477#ifdef DDB 478 char *newfilename; 479#endif 480 481 ef = (elf_file_t) lf; 482#if 0 /* this will be more trouble than it's worth for now */ 483 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 484 if (dp->d_tag != DT_NEEDED) 485 continue; 486 modname = ef->strtab + dp->d_un.d_val; 487 error = linker_load_module(modname, lf); 488 if (error) 489 goto out; 490 } 491#endif 492 error = relocate_file(ef); 493 if (error) 494 return error; 495 (void)link_elf_preload_parse_symbols(ef); 496 497#ifdef DDB 498 GDB_STATE(RT_ADD); 499 ef->gdb.l_addr = lf->address; 500 newfilename = malloc(strlen(lf->filename) + 1, M_LINKER, M_WAITOK); 501 strcpy(newfilename, lf->filename); 502 ef->gdb.l_name = newfilename; 503 ef->gdb.l_ld = ef->dynamic; 504 link_elf_add_gdb(&ef->gdb); 505 GDB_STATE(RT_CONSISTENT); 506#endif 507 508 return (0); 509} 510 511static int 512link_elf_load_file(linker_class_t cls, const char* filename, linker_file_t* result) 513{ 514 struct nameidata nd; 515 struct thread* td = curthread; /* XXX */ 516 Elf_Ehdr *hdr; 517 caddr_t firstpage; 518 int nbytes, i; 519 Elf_Phdr *phdr; 520 Elf_Phdr *phlimit; 521 Elf_Phdr *segs[2]; 522 int nsegs; 523 Elf_Phdr *phdyn; 524 Elf_Phdr *phphdr; 525 caddr_t mapbase; 526 size_t mapsize; 527 Elf_Off base_offset; 528 Elf_Addr base_vaddr; 529 Elf_Addr base_vlimit; 530 int error = 0; 531 int resid, flags; 532 elf_file_t ef; 533 linker_file_t lf; 534 Elf_Shdr *shdr; 535 int symtabindex; 536 int symstrindex; 537 int symcnt; 538 int strcnt; 539#ifdef DDB 540 char *newfilename; 541#endif 542 543 GIANT_REQUIRED; 544 545 shdr = NULL; 546 lf = NULL; 547 548 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, td); 549 flags = FREAD; 550 error = vn_open(&nd, &flags, 0); 551 if (error) 552 return error; 553 NDFREE(&nd, NDF_ONLY_PNBUF); 554 555 /* 556 * Read the elf header from the file. 557 */ 558 firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK); 559 if (firstpage == NULL) { 560 error = ENOMEM; 561 goto out; 562 } 563 hdr = (Elf_Ehdr *)firstpage; 564 error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0, 565 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 566 &resid, td); 567 nbytes = PAGE_SIZE - resid; 568 if (error) 569 goto out; 570 571 if (!IS_ELF(*hdr)) { 572 error = ENOEXEC; 573 goto out; 574 } 575 576 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 577 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 578 link_elf_error("Unsupported file layout"); 579 error = ENOEXEC; 580 goto out; 581 } 582 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 583 || hdr->e_version != EV_CURRENT) { 584 link_elf_error("Unsupported file version"); 585 error = ENOEXEC; 586 goto out; 587 } 588 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 589 link_elf_error("Unsupported file type"); 590 error = ENOEXEC; 591 goto out; 592 } 593 if (hdr->e_machine != ELF_TARG_MACH) { 594 link_elf_error("Unsupported machine"); 595 error = ENOEXEC; 596 goto out; 597 } 598 599 /* 600 * We rely on the program header being in the first page. This is 601 * not strictly required by the ABI specification, but it seems to 602 * always true in practice. And, it simplifies things considerably. 603 */ 604 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 605 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 606 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 607 link_elf_error("Unreadable program headers"); 608 609 /* 610 * Scan the program header entries, and save key information. 611 * 612 * We rely on there being exactly two load segments, text and data, 613 * in that order. 614 */ 615 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 616 phlimit = phdr + hdr->e_phnum; 617 nsegs = 0; 618 phdyn = NULL; 619 phphdr = NULL; 620 while (phdr < phlimit) { 621 switch (phdr->p_type) { 622 623 case PT_LOAD: 624 if (nsegs == 2) { 625 link_elf_error("Too many sections"); 626 error = ENOEXEC; 627 goto out; 628 } 629 segs[nsegs] = phdr; 630 ++nsegs; 631 break; 632 633 case PT_PHDR: 634 phphdr = phdr; 635 break; 636 637 case PT_DYNAMIC: 638 phdyn = phdr; 639 break; 640 641 case PT_INTERP: 642 link_elf_error("Unsupported file type"); 643 error = ENOEXEC; 644 goto out; 645 } 646 647 ++phdr; 648 } 649 if (phdyn == NULL) { 650 link_elf_error("Object is not dynamically-linked"); 651 error = ENOEXEC; 652 goto out; 653 } 654 655 /* 656 * Allocate the entire address space of the object, to stake out our 657 * contiguous region, and to establish the base address for relocation. 658 */ 659 base_offset = trunc_page(segs[0]->p_offset); 660 base_vaddr = trunc_page(segs[0]->p_vaddr); 661 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); 662 mapsize = base_vlimit - base_vaddr; 663 664 lf = linker_make_file(filename, &link_elf_class); 665 if (!lf) { 666 error = ENOMEM; 667 goto out; 668 } 669 670 ef = (elf_file_t) lf; 671#ifdef SPARSE_MAPPING 672 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 673 if (ef->object == NULL) { 674 error = ENOMEM; 675 goto out; 676 } 677 vm_object_reference(ef->object); 678 ef->address = (caddr_t) vm_map_min(kernel_map); 679 error = vm_map_find(kernel_map, ef->object, 0, 680 (vm_offset_t *) &ef->address, 681 mapsize, 1, 682 VM_PROT_ALL, VM_PROT_ALL, 0); 683 if (error) { 684 vm_object_deallocate(ef->object); 685 ef->object = 0; 686 goto out; 687 } 688#else 689 ef->address = malloc(mapsize, M_LINKER, M_WAITOK); 690 if (!ef->address) { 691 error = ENOMEM; 692 goto out; 693 } 694#endif 695 mapbase = ef->address; 696 697 /* 698 * Read the text and data sections and zero the bss. 699 */ 700 for (i = 0; i < 2; i++) { 701 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 702 error = vn_rdwr(UIO_READ, nd.ni_vp, 703 segbase, segs[i]->p_filesz, segs[i]->p_offset, 704 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 705 &resid, td); 706 if (error) { 707 goto out; 708 } 709 bzero(segbase + segs[i]->p_filesz, 710 segs[i]->p_memsz - segs[i]->p_filesz); 711 712#ifdef SPARSE_MAPPING 713 /* 714 * Wire down the pages 715 */ 716 vm_map_wire(kernel_map, 717 (vm_offset_t) segbase, 718 (vm_offset_t) segbase + segs[i]->p_memsz, 719 FALSE); 720#endif 721 } 722 723#ifdef GPROF 724 /* Update profiling information with the new text segment. */ 725 kmupetext((uintfptr_t)(mapbase + segs[0]->p_vaddr - base_vaddr + 726 segs[0]->p_memsz)); 727#endif 728 729 ef->dynamic = (Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 730 731 lf->address = ef->address; 732 lf->size = mapsize; 733 734 error = parse_dynamic(ef); 735 if (error) 736 goto out; 737 error = linker_load_dependencies(lf); 738 if (error) 739 goto out; 740#if 0 /* this will be more trouble than it's worth for now */ 741 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 742 if (dp->d_tag != DT_NEEDED) 743 continue; 744 modname = ef->strtab + dp->d_un.d_val; 745 error = linker_load_module(modname, lf); 746 if (error) 747 goto out; 748 } 749#endif 750 error = relocate_file(ef); 751 if (error) 752 goto out; 753 754 /* Try and load the symbol table if it's present. (you can strip it!) */ 755 nbytes = hdr->e_shnum * hdr->e_shentsize; 756 if (nbytes == 0 || hdr->e_shoff == 0) 757 goto nosyms; 758 shdr = malloc(nbytes, M_LINKER, M_WAITOK | M_ZERO); 759 if (shdr == NULL) { 760 error = ENOMEM; 761 goto out; 762 } 763 error = vn_rdwr(UIO_READ, nd.ni_vp, 764 (caddr_t)shdr, nbytes, hdr->e_shoff, 765 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 766 &resid, td); 767 if (error) 768 goto out; 769 symtabindex = -1; 770 symstrindex = -1; 771 for (i = 0; i < hdr->e_shnum; i++) { 772 if (shdr[i].sh_type == SHT_SYMTAB) { 773 symtabindex = i; 774 symstrindex = shdr[i].sh_link; 775 } 776 } 777 if (symtabindex < 0 || symstrindex < 0) 778 goto nosyms; 779 780 symcnt = shdr[symtabindex].sh_size; 781 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK); 782 strcnt = shdr[symstrindex].sh_size; 783 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK); 784 785 if (ef->symbase == NULL || ef->strbase == NULL) { 786 error = ENOMEM; 787 goto out; 788 } 789 error = vn_rdwr(UIO_READ, nd.ni_vp, 790 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 791 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 792 &resid, td); 793 if (error) 794 goto out; 795 error = vn_rdwr(UIO_READ, nd.ni_vp, 796 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 797 UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, 798 &resid, td); 799 if (error) 800 goto out; 801 802 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 803 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 804 ef->ddbstrcnt = strcnt; 805 ef->ddbstrtab = ef->strbase; 806 807#ifdef DDB 808 GDB_STATE(RT_ADD); 809 ef->gdb.l_addr = lf->address; 810 newfilename = malloc(strlen(filename) + 1, M_LINKER, M_WAITOK); 811 strcpy(newfilename, filename); 812 ef->gdb.l_name = (const char *)newfilename; 813 ef->gdb.l_ld = ef->dynamic; 814 link_elf_add_gdb(&ef->gdb); 815 GDB_STATE(RT_CONSISTENT); 816#endif 817 818nosyms: 819 820 *result = lf; 821 822out: 823 if (error && lf) 824 linker_file_unload(lf); 825 if (shdr) 826 free(shdr, M_LINKER); 827 if (firstpage) 828 free(firstpage, M_LINKER); 829 VOP_UNLOCK(nd.ni_vp, 0, td); 830 vn_close(nd.ni_vp, FREAD, td->td_ucred, td); 831 832 return error; 833} 834 835static void 836link_elf_unload_file(linker_file_t file) 837{ 838 elf_file_t ef = (elf_file_t) file; 839 840#ifdef DDB 841 if (ef->gdb.l_ld) { 842 GDB_STATE(RT_DELETE); 843 free((void *)(uintptr_t)ef->gdb.l_name, M_LINKER); 844 link_elf_delete_gdb(&ef->gdb); 845 GDB_STATE(RT_CONSISTENT); 846 } 847#endif 848 849 if (ef->preloaded) { 850 link_elf_unload_preload(file); 851 return; 852 } 853#ifdef SPARSE_MAPPING 854 if (ef->object) { 855 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 856 (vm_offset_t) ef->address 857 + (ef->object->size << PAGE_SHIFT)); 858 vm_object_deallocate(ef->object); 859 } 860#else 861 if (ef->address) 862 free(ef->address, M_LINKER); 863#endif 864 if (ef->symbase) 865 free(ef->symbase, M_LINKER); 866 if (ef->strbase) 867 free(ef->strbase, M_LINKER); 868} 869 870static void 871link_elf_unload_preload(linker_file_t file) 872{ 873 if (file->filename) 874 preload_delete_name(file->filename); 875} 876 877static const char * 878symbol_name(elf_file_t ef, Elf_Word r_info) 879{ 880 const Elf_Sym *ref; 881 882 if (ELF_R_SYM(r_info)) { 883 ref = ef->symtab + ELF_R_SYM(r_info); 884 return ef->strtab + ref->st_name; 885 } else 886 return NULL; 887} 888 889static int 890relocate_file(elf_file_t ef) 891{ 892 const Elf_Rel *rellim; 893 const Elf_Rel *rel; 894 const Elf_Rela *relalim; 895 const Elf_Rela *rela; 896 const char *symname; 897 898 /* Perform relocations without addend if there are any: */ 899 rel = ef->rel; 900 if (rel) { 901 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 902 while (rel < rellim) { 903 if (elf_reloc(&ef->lf, rel, ELF_RELOC_REL)) { 904 symname = symbol_name(ef, rel->r_info); 905 printf("link_elf: symbol %s undefined\n", symname); 906 return ENOENT; 907 } 908 rel++; 909 } 910 } 911 912 /* Perform relocations with addend if there are any: */ 913 rela = ef->rela; 914 if (rela) { 915 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 916 while (rela < relalim) { 917 if (elf_reloc(&ef->lf, rela, ELF_RELOC_RELA)) { 918 symname = symbol_name(ef, rela->r_info); 919 printf("link_elf: symbol %s undefined\n", symname); 920 return ENOENT; 921 } 922 rela++; 923 } 924 } 925 926 /* Perform PLT relocations without addend if there are any: */ 927 rel = ef->pltrel; 928 if (rel) { 929 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 930 while (rel < rellim) { 931 if (elf_reloc(&ef->lf, rel, ELF_RELOC_REL)) { 932 symname = symbol_name(ef, rel->r_info); 933 printf("link_elf: symbol %s undefined\n", symname); 934 return ENOENT; 935 } 936 rel++; 937 } 938 } 939 940 /* Perform relocations with addend if there are any: */ 941 rela = ef->pltrela; 942 if (rela) { 943 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 944 while (rela < relalim) { 945 if (elf_reloc(&ef->lf, rela, ELF_RELOC_RELA)) { 946 symname = symbol_name(ef, rela->r_info); 947 printf("link_elf: symbol %s undefined\n", symname); 948 return ENOENT; 949 } 950 rela++; 951 } 952 } 953 954 return 0; 955} 956 957/* 958 * Hash function for symbol table lookup. Don't even think about changing 959 * this. It is specified by the System V ABI. 960 */ 961static unsigned long 962elf_hash(const char *name) 963{ 964 const unsigned char *p = (const unsigned char *) name; 965 unsigned long h = 0; 966 unsigned long g; 967 968 while (*p != '\0') { 969 h = (h << 4) + *p++; 970 if ((g = h & 0xf0000000) != 0) 971 h ^= g >> 24; 972 h &= ~g; 973 } 974 return h; 975} 976 977static int 978link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 979{ 980 elf_file_t ef = (elf_file_t) lf; 981 unsigned long symnum; 982 const Elf_Sym* symp; 983 const char *strp; 984 unsigned long hash; 985 int i; 986 987 /* First, search hashed global symbols */ 988 hash = elf_hash(name); 989 symnum = ef->buckets[hash % ef->nbuckets]; 990 991 while (symnum != STN_UNDEF) { 992 if (symnum >= ef->nchains) { 993 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 994 return ENOENT; 995 } 996 997 symp = ef->symtab + symnum; 998 if (symp->st_name == 0) { 999 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 1000 return ENOENT; 1001 } 1002 1003 strp = ef->strtab + symp->st_name; 1004 1005 if (strcmp(name, strp) == 0) { 1006 if (symp->st_shndx != SHN_UNDEF || 1007 (symp->st_value != 0 && 1008 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 1009 *sym = (c_linker_sym_t) symp; 1010 return 0; 1011 } else 1012 return ENOENT; 1013 } 1014 1015 symnum = ef->chains[symnum]; 1016 } 1017 1018 /* If we have not found it, look at the full table (if loaded) */ 1019 if (ef->symtab == ef->ddbsymtab) 1020 return ENOENT; 1021 1022 /* Exhaustive search */ 1023 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 1024 strp = ef->ddbstrtab + symp->st_name; 1025 if (strcmp(name, strp) == 0) { 1026 if (symp->st_shndx != SHN_UNDEF || 1027 (symp->st_value != 0 && 1028 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 1029 *sym = (c_linker_sym_t) symp; 1030 return 0; 1031 } else 1032 return ENOENT; 1033 } 1034 } 1035 1036 return ENOENT; 1037} 1038 1039static int 1040link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval) 1041{ 1042 elf_file_t ef = (elf_file_t) lf; 1043 const Elf_Sym* es = (const Elf_Sym*) sym; 1044 1045 if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) { 1046 symval->name = ef->strtab + es->st_name; 1047 symval->value = (caddr_t) ef->address + es->st_value; 1048 symval->size = es->st_size; 1049 return 0; 1050 } 1051 if (ef->symtab == ef->ddbsymtab) 1052 return ENOENT; 1053 if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) { 1054 symval->name = ef->ddbstrtab + es->st_name; 1055 symval->value = (caddr_t) ef->address + es->st_value; 1056 symval->size = es->st_size; 1057 return 0; 1058 } 1059 return ENOENT; 1060} 1061 1062static int 1063link_elf_search_symbol(linker_file_t lf, caddr_t value, 1064 c_linker_sym_t* sym, long* diffp) 1065{ 1066 elf_file_t ef = (elf_file_t) lf; 1067 u_long off = (uintptr_t) (void *) value; 1068 u_long diff = off; 1069 u_long st_value; 1070 const Elf_Sym* es; 1071 const Elf_Sym* best = 0; 1072 int i; 1073 1074 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 1075 if (es->st_name == 0) 1076 continue; 1077 st_value = es->st_value + (uintptr_t) (void *) ef->address; 1078 if (off >= st_value) { 1079 if (off - st_value < diff) { 1080 diff = off - st_value; 1081 best = es; 1082 if (diff == 0) 1083 break; 1084 } else if (off - st_value == diff) { 1085 best = es; 1086 } 1087 } 1088 } 1089 if (best == 0) 1090 *diffp = off; 1091 else 1092 *diffp = diff; 1093 *sym = (c_linker_sym_t) best; 1094 1095 return 0; 1096} 1097 1098/* 1099 * Look up a linker set on an ELF system. 1100 */ 1101static int 1102link_elf_lookup_set(linker_file_t lf, const char *name, 1103 void ***startp, void ***stopp, int *countp) 1104{ 1105 c_linker_sym_t sym; 1106 linker_symval_t symval; 1107 char *setsym; 1108 void **start, **stop; 1109 int len, error = 0, count; 1110 1111 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */ 1112 setsym = malloc(len, M_LINKER, M_WAITOK); 1113 if (setsym == NULL) 1114 return ENOMEM; 1115 1116 /* get address of first entry */ 1117 snprintf(setsym, len, "%s%s", "__start_set_", name); 1118 error = link_elf_lookup_symbol(lf, setsym, &sym); 1119 if (error) 1120 goto out; 1121 link_elf_symbol_values(lf, sym, &symval); 1122 if (symval.value == 0) { 1123 error = ESRCH; 1124 goto out; 1125 } 1126 start = (void **)symval.value; 1127 1128 /* get address of last entry */ 1129 snprintf(setsym, len, "%s%s", "__stop_set_", name); 1130 error = link_elf_lookup_symbol(lf, setsym, &sym); 1131 if (error) 1132 goto out; 1133 link_elf_symbol_values(lf, sym, &symval); 1134 if (symval.value == 0) { 1135 error = ESRCH; 1136 goto out; 1137 } 1138 stop = (void **)symval.value; 1139 1140 /* and the number of entries */ 1141 count = stop - start; 1142 1143 /* and copy out */ 1144 if (startp) 1145 *startp = start; 1146 if (stopp) 1147 *stopp = stop; 1148 if (countp) 1149 *countp = count; 1150 1151out: 1152 free(setsym, M_LINKER); 1153 return error; 1154} 1155 1156static int 1157link_elf_each_function_name(linker_file_t file, 1158 int (*callback)(const char *, void *), void *opaque) { 1159 elf_file_t ef = (elf_file_t)file; 1160 const Elf_Sym* symp; 1161 int i, error; 1162 1163 /* Exhaustive search */ 1164 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 1165 if (symp->st_value != 0 && 1166 ELF_ST_TYPE(symp->st_info) == STT_FUNC) { 1167 error = callback(ef->ddbstrtab + symp->st_name, opaque); 1168 if (error) 1169 return (error); 1170 } 1171 } 1172 return (0); 1173} 1174 1175#ifdef __ia64__ 1176/* 1177 * Each KLD has its own GP. The GP value for each load module is given by 1178 * DT_PLTGOT on ia64. We need GP to construct function descriptors, but 1179 * don't have direct access to the ELF file structure. The link_elf_get_gp() 1180 * function returns the GP given a pointer to a generic linker file struct. 1181 */ 1182Elf_Addr 1183link_elf_get_gp(linker_file_t lf) 1184{ 1185 elf_file_t ef = (elf_file_t)lf; 1186 return (Elf_Addr)ef->got; 1187} 1188#endif 1189 1190const Elf_Sym * 1191elf_get_sym(linker_file_t lf, Elf_Word symidx) 1192{ 1193 elf_file_t ef = (elf_file_t)lf; 1194 1195 if (symidx >= ef->nchains) 1196 return (NULL); 1197 return (ef->symtab + symidx); 1198} 1199 1200const char * 1201elf_get_symname(linker_file_t lf, Elf_Word symidx) 1202{ 1203 elf_file_t ef = (elf_file_t)lf; 1204 const Elf_Sym *sym; 1205 1206 if (symidx >= ef->nchains) 1207 return (NULL); 1208 sym = ef->symtab + symidx; 1209 return (ef->strtab + sym->st_name); 1210} 1211 1212/* 1213 * Symbol lookup function that can be used when the symbol index is known (ie 1214 * in relocations). It uses the symbol index instead of doing a fully fledged 1215 * hash table based lookup when such is valid. For example for local symbols. 1216 * This is not only more efficient, it's also more correct. It's not always 1217 * the case that the symbol can be found through the hash table. 1218 */ 1219Elf_Addr 1220elf_lookup(linker_file_t lf, Elf_Word symidx, int deps) 1221{ 1222 elf_file_t ef = (elf_file_t)lf; 1223 const Elf_Sym *sym; 1224 const char *symbol; 1225 1226 /* Don't even try to lookup the symbol if the index is bogus. */ 1227 if (symidx >= ef->nchains) 1228 return (0); 1229 1230 sym = ef->symtab + symidx; 1231 1232 /* 1233 * Don't do a full lookup when the symbol is local. It may even 1234 * fail because it may not be found through the hash table. 1235 */ 1236 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) { 1237 /* Force lookup failure when we have an insanity. */ 1238 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0) 1239 return (0); 1240 return ((Elf_Addr)ef->address + sym->st_value); 1241 } 1242 1243 /* 1244 * XXX we can avoid doing a hash table based lookup for global 1245 * symbols as well. This however is not always valid, so we'll 1246 * just do it the hard way for now. Performance tweaks can 1247 * always be added. 1248 */ 1249 1250 symbol = ef->strtab + sym->st_name; 1251 1252 /* Force a lookup failure if the symbol name is bogus. */ 1253 if (*symbol == 0) 1254 return (0); 1255 1256 return ((Elf_Addr)linker_file_lookup_symbol(lf, symbol, deps)); 1257} 1258