link_elf.c revision 52635
1/*- 2 * Copyright (c) 1998 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 52635 1999-10-29 18:09:36Z phk $ 27 */ 28 29#include <sys/param.h> 30#include <sys/kernel.h> 31#include <sys/systm.h> 32#include <sys/malloc.h> 33#include <sys/proc.h> 34#include <sys/namei.h> 35#include <sys/fcntl.h> 36#include <sys/vnode.h> 37#include <sys/linker.h> 38#include <machine/elf.h> 39 40#include <vm/vm.h> 41#ifdef SPARSE_MAPPING 42#endif 43#include <vm/vm_param.h> 44#include <sys/lock.h> 45#ifdef SPARSE_MAPPING 46#include <vm/vm_object.h> 47#include <vm/vm_kern.h> 48#include <vm/vm_extern.h> 49#endif 50#include <vm/pmap.h> 51#include <vm/vm_map.h> 52 53static int link_elf_load_module(const char*, linker_file_t*); 54static int link_elf_load_file(const char*, linker_file_t*); 55static int link_elf_lookup_symbol(linker_file_t, const char*, 56 c_linker_sym_t*); 57static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*); 58static int link_elf_search_symbol(linker_file_t, caddr_t value, 59 c_linker_sym_t* sym, long* diffp); 60 61static void link_elf_unload_file(linker_file_t); 62static void link_elf_unload_module(linker_file_t); 63 64static struct linker_class_ops link_elf_class_ops = { 65 link_elf_load_module, 66}; 67 68static struct linker_file_ops link_elf_file_ops = { 69 link_elf_lookup_symbol, 70 link_elf_symbol_values, 71 link_elf_search_symbol, 72 link_elf_unload_file, 73}; 74 75static struct linker_file_ops link_elf_module_ops = { 76 link_elf_lookup_symbol, 77 link_elf_symbol_values, 78 link_elf_search_symbol, 79 link_elf_unload_module, 80}; 81typedef struct elf_file { 82 caddr_t address; /* Relocation address */ 83#ifdef SPARSE_MAPPING 84 vm_object_t object; /* VM object to hold file pages */ 85#endif 86 const Elf_Dyn* dynamic; /* Symbol table etc. */ 87 Elf_Off nbuckets; /* DT_HASH info */ 88 Elf_Off nchains; 89 const Elf_Off* buckets; 90 const Elf_Off* chains; 91 caddr_t hash; 92 caddr_t strtab; /* DT_STRTAB */ 93 int strsz; /* DT_STRSZ */ 94 const Elf_Sym* symtab; /* DT_SYMTAB */ 95 Elf_Addr* got; /* DT_PLTGOT */ 96 const Elf_Rel* pltrel; /* DT_JMPREL */ 97 int pltrelsize; /* DT_PLTRELSZ */ 98 const Elf_Rela* pltrela; /* DT_JMPREL */ 99 int pltrelasize; /* DT_PLTRELSZ */ 100 const Elf_Rel* rel; /* DT_REL */ 101 int relsize; /* DT_RELSZ */ 102 const Elf_Rela* rela; /* DT_RELA */ 103 int relasize; /* DT_RELASZ */ 104 caddr_t modptr; 105 const Elf_Sym* ddbsymtab; /* The symbol table we are using */ 106 long ddbsymcnt; /* Number of symbols */ 107 caddr_t ddbstrtab; /* String table */ 108 long ddbstrcnt; /* number of bytes in string table */ 109 caddr_t symbase; /* malloc'ed symbold base */ 110 caddr_t strbase; /* malloc'ed string base */ 111} *elf_file_t; 112 113static int parse_dynamic(linker_file_t lf); 114static int load_dependancies(linker_file_t lf); 115static int relocate_file(linker_file_t lf); 116static int parse_module_symbols(linker_file_t lf); 117 118/* 119 * The kernel symbol table starts here. 120 */ 121extern struct _dynamic _DYNAMIC; 122 123static void 124link_elf_init(void* arg) 125{ 126#ifdef __ELF__ 127 Elf_Dyn *dp; 128 caddr_t modptr, baseptr, sizeptr; 129 elf_file_t ef; 130 char *modname; 131#endif 132 133#if ELF_TARG_CLASS == ELFCLASS32 134 linker_add_class("elf32", NULL, &link_elf_class_ops); 135#else 136 linker_add_class("elf64", NULL, &link_elf_class_ops); 137#endif 138 139#ifdef __ELF__ 140 dp = (Elf_Dyn*) &_DYNAMIC; 141 if (dp) { 142 ef = malloc(sizeof(struct elf_file), M_LINKER, M_NOWAIT); 143 if (ef == NULL) 144 panic("link_elf_init: Can't create linker structures for kernel"); 145 bzero(ef, sizeof(*ef)); 146 147 ef->address = 0; 148#ifdef SPARSE_MAPPING 149 ef->object = 0; 150#endif 151 ef->dynamic = dp; 152 modname = NULL; 153 modptr = preload_search_by_type("elf kernel"); 154 if (modptr) 155 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 156 if (modname == NULL) 157 modname = "kernel"; 158 linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops); 159 if (linker_kernel_file == NULL) 160 panic("link_elf_init: Can't create linker structures for kernel"); 161 parse_dynamic(linker_kernel_file); 162 linker_kernel_file->address = (caddr_t) KERNBASE; 163 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address; 164 165 if (modptr) { 166 ef->modptr = modptr; 167 baseptr = preload_search_info(modptr, MODINFO_ADDR); 168 if (baseptr) 169 linker_kernel_file->address = *(caddr_t *)baseptr; 170 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 171 if (sizeptr) 172 linker_kernel_file->size = *(size_t *)sizeptr; 173 } 174 (void)parse_module_symbols(linker_kernel_file); 175 linker_current_file = linker_kernel_file; 176 linker_kernel_file->flags |= LINKER_FILE_LINKED; 177 } 178#endif 179} 180 181SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0); 182 183static int 184parse_module_symbols(linker_file_t lf) 185{ 186 elf_file_t ef = lf->priv; 187 caddr_t pointer; 188 caddr_t ssym, esym, base; 189 caddr_t strtab; 190 int strcnt; 191 Elf_Sym* symtab; 192 int symcnt; 193 194 if (ef->modptr == NULL) 195 return 0; 196 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 197 if (pointer == NULL) 198 return 0; 199 ssym = *(caddr_t *)pointer; 200 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 201 if (pointer == NULL) 202 return 0; 203 esym = *(caddr_t *)pointer; 204 205 base = ssym; 206 207 symcnt = *(long *)base; 208 base += sizeof(long); 209 symtab = (Elf_Sym *)base; 210 base += roundup(symcnt, sizeof(long)); 211 212 if (base > esym || base < ssym) { 213 printf("Symbols are corrupt!\n"); 214 return EINVAL; 215 } 216 217 strcnt = *(long *)base; 218 base += sizeof(long); 219 strtab = base; 220 base += roundup(strcnt, sizeof(long)); 221 222 if (base > esym || base < ssym) { 223 printf("Symbols are corrupt!\n"); 224 return EINVAL; 225 } 226 227 ef->ddbsymtab = symtab; 228 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 229 ef->ddbstrtab = strtab; 230 ef->ddbstrcnt = strcnt; 231 232 return 0; 233} 234 235static int 236parse_dynamic(linker_file_t lf) 237{ 238 elf_file_t ef = lf->priv; 239 const Elf_Dyn *dp; 240 int plttype = DT_REL; 241 242 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 243 switch (dp->d_tag) { 244 case DT_HASH: 245 { 246 /* From src/libexec/rtld-elf/rtld.c */ 247 const Elf_Off *hashtab = (const Elf_Off *) 248 (ef->address + dp->d_un.d_ptr); 249 ef->nbuckets = hashtab[0]; 250 ef->nchains = hashtab[1]; 251 ef->buckets = hashtab + 2; 252 ef->chains = ef->buckets + ef->nbuckets; 253 break; 254 } 255 case DT_STRTAB: 256 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 257 break; 258 case DT_STRSZ: 259 ef->strsz = dp->d_un.d_val; 260 break; 261 case DT_SYMTAB: 262 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 263 break; 264 case DT_SYMENT: 265 if (dp->d_un.d_val != sizeof(Elf_Sym)) 266 return ENOEXEC; 267 break; 268 case DT_PLTGOT: 269 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 270 break; 271 case DT_REL: 272 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 273 break; 274 case DT_RELSZ: 275 ef->relsize = dp->d_un.d_val; 276 break; 277 case DT_RELENT: 278 if (dp->d_un.d_val != sizeof(Elf_Rel)) 279 return ENOEXEC; 280 break; 281 case DT_JMPREL: 282 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 283 break; 284 case DT_PLTRELSZ: 285 ef->pltrelsize = dp->d_un.d_val; 286 break; 287 case DT_RELA: 288 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 289 break; 290 case DT_RELASZ: 291 ef->relasize = dp->d_un.d_val; 292 break; 293 case DT_RELAENT: 294 if (dp->d_un.d_val != sizeof(Elf_Rela)) 295 return ENOEXEC; 296 break; 297 case DT_PLTREL: 298 plttype = dp->d_un.d_val; 299 if (plttype != DT_REL && plttype != DT_RELA) 300 return ENOEXEC; 301 break; 302 } 303 } 304 305 if (plttype == DT_RELA) { 306 ef->pltrela = (const Elf_Rela *) ef->pltrel; 307 ef->pltrel = NULL; 308 ef->pltrelasize = ef->pltrelsize; 309 ef->pltrelsize = 0; 310 } 311 312 ef->ddbsymtab = ef->symtab; 313 ef->ddbsymcnt = ef->nchains; 314 ef->ddbstrtab = ef->strtab; 315 ef->ddbstrcnt = ef->strsz; 316 317 return 0; 318} 319 320static void 321link_elf_error(const char *s) 322{ 323 printf("kldload: %s\n", s); 324} 325 326static int 327link_elf_load_module(const char *filename, linker_file_t *result) 328{ 329 caddr_t modptr, baseptr, sizeptr, dynptr; 330 char *type; 331 elf_file_t ef; 332 linker_file_t lf; 333 int error; 334 vm_offset_t dp; 335 336 /* Look to see if we have the module preloaded */ 337 modptr = preload_search_by_name(filename); 338 if (modptr == NULL) 339 return (link_elf_load_file(filename, result)); 340 341 /* It's preloaded, check we can handle it and collect information */ 342 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 343 baseptr = preload_search_info(modptr, MODINFO_ADDR); 344 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 345 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 346 if (type == NULL || strcmp(type, "elf module") != 0) 347 return (EFTYPE); 348 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 349 return (EINVAL); 350 351 ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK); 352 if (ef == NULL) 353 return (ENOMEM); 354 bzero(ef, sizeof(*ef)); 355 ef->modptr = modptr; 356 ef->address = *(caddr_t *)baseptr; 357#ifdef SPARSE_MAPPING 358 ef->object = 0; 359#endif 360 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 361 ef->dynamic = (Elf_Dyn *)dp; 362 lf = linker_make_file(filename, ef, &link_elf_module_ops); 363 if (lf == NULL) { 364 free(ef, M_LINKER); 365 return ENOMEM; 366 } 367 lf->address = ef->address; 368 lf->size = *(size_t *)sizeptr; 369 370 error = parse_dynamic(lf); 371 if (error) { 372 linker_file_unload(lf); 373 return error; 374 } 375 error = load_dependancies(lf); 376 if (error) { 377 linker_file_unload(lf); 378 return error; 379 } 380 error = relocate_file(lf); 381 if (error) { 382 linker_file_unload(lf); 383 return error; 384 } 385 (void)parse_module_symbols(lf); 386 lf->flags |= LINKER_FILE_LINKED; 387 *result = lf; 388 return (0); 389} 390 391static int 392link_elf_load_file(const char* filename, linker_file_t* result) 393{ 394 struct nameidata nd; 395 struct proc* p = curproc; /* XXX */ 396 Elf_Ehdr *hdr; 397 caddr_t firstpage; 398 int nbytes, i; 399 Elf_Phdr *phdr; 400 Elf_Phdr *phlimit; 401 Elf_Phdr *segs[2]; 402 int nsegs; 403 Elf_Phdr *phdyn; 404 Elf_Phdr *phphdr; 405 caddr_t mapbase; 406 size_t mapsize; 407 Elf_Off base_offset; 408 Elf_Addr base_vaddr; 409 Elf_Addr base_vlimit; 410 int error = 0; 411 int resid; 412 elf_file_t ef; 413 linker_file_t lf; 414 char *pathname; 415 Elf_Shdr *shdr; 416 int symtabindex; 417 int symstrindex; 418 int symcnt; 419 int strcnt; 420 421 shdr = NULL; 422 lf = NULL; 423 424 pathname = linker_search_path(filename); 425 if (pathname == NULL) 426 return ENOENT; 427 428 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, pathname, p); 429 error = vn_open(&nd, FREAD, 0); 430 free(pathname, M_LINKER); 431 if (error) 432 return error; 433 434 /* 435 * Read the elf header from the file. 436 */ 437 firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK); 438 if (firstpage == NULL) { 439 error = ENOMEM; 440 goto out; 441 } 442 hdr = (Elf_Ehdr *)firstpage; 443 error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0, 444 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p); 445 nbytes = PAGE_SIZE - resid; 446 if (error) 447 goto out; 448 449 if (!IS_ELF(*hdr)) { 450 error = ENOEXEC; 451 goto out; 452 } 453 454 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 455 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 456 link_elf_error("Unsupported file layout"); 457 error = ENOEXEC; 458 goto out; 459 } 460 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 461 || hdr->e_version != EV_CURRENT) { 462 link_elf_error("Unsupported file version"); 463 error = ENOEXEC; 464 goto out; 465 } 466 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 467 link_elf_error("Unsupported file type"); 468 error = ENOEXEC; 469 goto out; 470 } 471 if (hdr->e_machine != ELF_TARG_MACH) { 472 link_elf_error("Unsupported machine"); 473 error = ENOEXEC; 474 goto out; 475 } 476 477 /* 478 * We rely on the program header being in the first page. This is 479 * not strictly required by the ABI specification, but it seems to 480 * always true in practice. And, it simplifies things considerably. 481 */ 482 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 483 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 484 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 485 link_elf_error("Unreadable program headers"); 486 487 /* 488 * Scan the program header entries, and save key information. 489 * 490 * We rely on there being exactly two load segments, text and data, 491 * in that order. 492 */ 493 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 494 phlimit = phdr + hdr->e_phnum; 495 nsegs = 0; 496 phdyn = NULL; 497 phphdr = NULL; 498 while (phdr < phlimit) { 499 switch (phdr->p_type) { 500 501 case PT_LOAD: 502 if (nsegs == 2) { 503 link_elf_error("Too many sections"); 504 error = ENOEXEC; 505 goto out; 506 } 507 segs[nsegs] = phdr; 508 ++nsegs; 509 break; 510 511 case PT_PHDR: 512 phphdr = phdr; 513 break; 514 515 case PT_DYNAMIC: 516 phdyn = phdr; 517 break; 518 } 519 520 ++phdr; 521 } 522 if (phdyn == NULL) { 523 link_elf_error("Object is not dynamically-linked"); 524 error = ENOEXEC; 525 goto out; 526 } 527 528 /* 529 * Allocate the entire address space of the object, to stake out our 530 * contiguous region, and to establish the base address for relocation. 531 */ 532 base_offset = trunc_page(segs[0]->p_offset); 533 base_vaddr = trunc_page(segs[0]->p_vaddr); 534 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); 535 mapsize = base_vlimit - base_vaddr; 536 537 ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK); 538 bzero(ef, sizeof(*ef)); 539#ifdef SPARSE_MAPPING 540 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 541 if (ef->object == NULL) { 542 free(ef, M_LINKER); 543 error = ENOMEM; 544 goto out; 545 } 546 vm_object_reference(ef->object); 547 ef->address = (caddr_t) vm_map_min(kernel_map); 548 error = vm_map_find(kernel_map, ef->object, 0, 549 (vm_offset_t *) &ef->address, 550 mapsize, 1, 551 VM_PROT_ALL, VM_PROT_ALL, 0); 552 if (error) { 553 vm_object_deallocate(ef->object); 554 free(ef, M_LINKER); 555 goto out; 556 } 557#else 558 ef->address = malloc(mapsize, M_LINKER, M_WAITOK); 559#endif 560 mapbase = ef->address; 561 562 /* 563 * Read the text and data sections and zero the bss. 564 */ 565 for (i = 0; i < 2; i++) { 566 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 567 error = vn_rdwr(UIO_READ, nd.ni_vp, 568 segbase, segs[i]->p_filesz, segs[i]->p_offset, 569 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p); 570 if (error) { 571#ifdef SPARSE_MAPPING 572 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 573 (vm_offset_t) ef->address 574 + (ef->object->size << PAGE_SHIFT)); 575 vm_object_deallocate(ef->object); 576#else 577 free(ef->address, M_LINKER); 578#endif 579 free(ef, M_LINKER); 580 goto out; 581 } 582 bzero(segbase + segs[i]->p_filesz, 583 segs[i]->p_memsz - segs[i]->p_filesz); 584 585#ifdef SPARSE_MAPPING 586 /* 587 * Wire down the pages 588 */ 589 vm_map_pageable(kernel_map, 590 (vm_offset_t) segbase, 591 (vm_offset_t) segbase + segs[i]->p_memsz, 592 FALSE); 593#endif 594 } 595 596 ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 597 598 lf = linker_make_file(filename, ef, &link_elf_file_ops); 599 if (lf == NULL) { 600#ifdef SPARSE_MAPPING 601 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 602 (vm_offset_t) ef->address 603 + (ef->object->size << PAGE_SHIFT)); 604 vm_object_deallocate(ef->object); 605#else 606 free(ef->address, M_LINKER); 607#endif 608 free(ef, M_LINKER); 609 error = ENOMEM; 610 goto out; 611 } 612 lf->address = ef->address; 613 lf->size = mapsize; 614 615 error = parse_dynamic(lf); 616 if (error) 617 goto out; 618 error = load_dependancies(lf); 619 if (error) 620 goto out; 621 error = relocate_file(lf); 622 if (error) 623 goto out; 624 625 /* Try and load the symbol table if it's present. (you can strip it!) */ 626 nbytes = hdr->e_shnum * hdr->e_shentsize; 627 if (nbytes == 0 || hdr->e_shoff == 0) 628 goto nosyms; 629 shdr = malloc(nbytes, M_LINKER, M_WAITOK); 630 if (shdr == NULL) { 631 error = ENOMEM; 632 goto out; 633 } 634 bzero(shdr, nbytes); 635 error = vn_rdwr(UIO_READ, nd.ni_vp, 636 (caddr_t)shdr, nbytes, hdr->e_shoff, 637 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p); 638 if (error) 639 goto out; 640 symtabindex = -1; 641 symstrindex = -1; 642 for (i = 0; i < hdr->e_shnum; i++) { 643 if (shdr[i].sh_type == SHT_SYMTAB) { 644 symtabindex = i; 645 symstrindex = shdr[i].sh_link; 646 } 647 } 648 if (symtabindex < 0 || symstrindex < 0) 649 goto nosyms; 650 651 symcnt = shdr[symtabindex].sh_size; 652 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK); 653 strcnt = shdr[symstrindex].sh_size; 654 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK); 655 656 if (ef->symbase == NULL || ef->strbase == NULL) { 657 error = ENOMEM; 658 goto out; 659 } 660 error = vn_rdwr(UIO_READ, nd.ni_vp, 661 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 662 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p); 663 if (error) 664 goto out; 665 error = vn_rdwr(UIO_READ, nd.ni_vp, 666 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 667 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p); 668 if (error) 669 goto out; 670 671 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 672 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 673 ef->ddbstrcnt = strcnt; 674 ef->ddbstrtab = ef->strbase; 675 676 lf->flags |= LINKER_FILE_LINKED; 677 678nosyms: 679 680 *result = lf; 681 682out: 683 if (error && lf) 684 linker_file_unload(lf); 685 if (shdr) 686 free(shdr, M_LINKER); 687 if (firstpage) 688 free(firstpage, M_LINKER); 689 VOP_UNLOCK(nd.ni_vp, 0, p); 690 vn_close(nd.ni_vp, FREAD, p->p_ucred, p); 691 692 return error; 693} 694 695static void 696link_elf_unload_file(linker_file_t file) 697{ 698 elf_file_t ef = file->priv; 699 700 if (ef) { 701#ifdef SPARSE_MAPPING 702 if (ef->object) { 703 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 704 (vm_offset_t) ef->address 705 + (ef->object->size << PAGE_SHIFT)); 706 vm_object_deallocate(ef->object); 707 } 708#else 709 if (ef->address) 710 free(ef->address, M_LINKER); 711#endif 712 if (ef->symbase) 713 free(ef->symbase, M_LINKER); 714 if (ef->strbase) 715 free(ef->strbase, M_LINKER); 716 free(ef, M_LINKER); 717 } 718} 719 720static void 721link_elf_unload_module(linker_file_t file) 722{ 723 elf_file_t ef = file->priv; 724 725 if (ef) 726 free(ef, M_LINKER); 727 if (file->filename) 728 preload_delete_name(file->filename); 729} 730 731static int 732load_dependancies(linker_file_t lf) 733{ 734 elf_file_t ef = lf->priv; 735 linker_file_t lfdep; 736 char* name; 737 const Elf_Dyn *dp; 738 int error = 0; 739 740 /* 741 * All files are dependant on /kernel. 742 */ 743 if (linker_kernel_file) { 744 linker_kernel_file->refs++; 745 linker_file_add_dependancy(lf, linker_kernel_file); 746 } 747 748 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 749 if (dp->d_tag == DT_NEEDED) { 750 name = ef->strtab + dp->d_un.d_val; 751 752 error = linker_load_file(name, &lfdep); 753 if (error) 754 goto out; 755 error = linker_file_add_dependancy(lf, lfdep); 756 if (error) 757 goto out; 758 } 759 } 760 761out: 762 return error; 763} 764 765static const char * 766symbol_name(elf_file_t ef, Elf_Word r_info) 767{ 768 const Elf_Sym *ref; 769 770 if (ELF_R_SYM(r_info)) { 771 ref = ef->symtab + ELF_R_SYM(r_info); 772 return ef->strtab + ref->st_name; 773 } else 774 return NULL; 775} 776 777static int 778relocate_file(linker_file_t lf) 779{ 780 elf_file_t ef = lf->priv; 781 const Elf_Rel *rellim; 782 const Elf_Rel *rel; 783 const Elf_Rela *relalim; 784 const Elf_Rela *rela; 785 const char *symname; 786 787 /* Perform relocations without addend if there are any: */ 788 rel = ef->rel; 789 if (rel) { 790 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 791 while (rel < rellim) { 792 symname = symbol_name(ef, rel->r_info); 793 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) { 794 printf("link_elf: symbol %s undefined\n", symname); 795 return ENOENT; 796 } 797 rel++; 798 } 799 } 800 801 /* Perform relocations with addend if there are any: */ 802 rela = ef->rela; 803 if (rela) { 804 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 805 while (rela < relalim) { 806 symname = symbol_name(ef, rela->r_info); 807 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) { 808 printf("link_elf: symbol %s undefined\n", symname); 809 return ENOENT; 810 } 811 rela++; 812 } 813 } 814 815 /* Perform PLT relocations without addend if there are any: */ 816 rel = ef->pltrel; 817 if (rel) { 818 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 819 while (rel < rellim) { 820 symname = symbol_name(ef, rel->r_info); 821 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) { 822 printf("link_elf: symbol %s undefined\n", symname); 823 return ENOENT; 824 } 825 rel++; 826 } 827 } 828 829 /* Perform relocations with addend if there are any: */ 830 rela = ef->pltrela; 831 if (rela) { 832 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 833 while (rela < relalim) { 834 symname = symbol_name(ef, rela->r_info); 835 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) { 836 printf("link_elf: symbol %s undefined\n", symname); 837 return ENOENT; 838 } 839 rela++; 840 } 841 } 842 843 return 0; 844} 845 846/* 847 * Hash function for symbol table lookup. Don't even think about changing 848 * this. It is specified by the System V ABI. 849 */ 850static unsigned long 851elf_hash(const char *name) 852{ 853 const unsigned char *p = (const unsigned char *) name; 854 unsigned long h = 0; 855 unsigned long g; 856 857 while (*p != '\0') { 858 h = (h << 4) + *p++; 859 if ((g = h & 0xf0000000) != 0) 860 h ^= g >> 24; 861 h &= ~g; 862 } 863 return h; 864} 865 866int 867link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 868{ 869 elf_file_t ef = lf->priv; 870 unsigned long symnum; 871 const Elf_Sym* symp; 872 const char *strp; 873 unsigned long hash; 874 int i; 875 876 /* First, search hashed global symbols */ 877 hash = elf_hash(name); 878 symnum = ef->buckets[hash % ef->nbuckets]; 879 880 while (symnum != STN_UNDEF) { 881 if (symnum >= ef->nchains) { 882 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 883 return ENOENT; 884 } 885 886 symp = ef->symtab + symnum; 887 if (symp->st_name == 0) { 888 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 889 return ENOENT; 890 } 891 892 strp = ef->strtab + symp->st_name; 893 894 if (strcmp(name, strp) == 0) { 895 if (symp->st_shndx != SHN_UNDEF || 896 (symp->st_value != 0 && 897 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 898 *sym = (c_linker_sym_t) symp; 899 return 0; 900 } else 901 return ENOENT; 902 } 903 904 symnum = ef->chains[symnum]; 905 } 906 907 /* If we have not found it, look at the full table (if loaded) */ 908 if (ef->symtab == ef->ddbsymtab) 909 return ENOENT; 910 911 /* Exhaustive search */ 912 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 913 strp = ef->ddbstrtab + symp->st_name; 914 if (strcmp(name, strp) == 0) { 915 if (symp->st_shndx != SHN_UNDEF || 916 (symp->st_value != 0 && 917 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 918 *sym = (c_linker_sym_t) symp; 919 return 0; 920 } else 921 return ENOENT; 922 } 923 } 924 925 return ENOENT; 926} 927 928static int 929link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval) 930{ 931 elf_file_t ef = lf->priv; 932 const Elf_Sym* es = (const Elf_Sym*) sym; 933 934 if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) { 935 symval->name = ef->strtab + es->st_name; 936 symval->value = (caddr_t) ef->address + es->st_value; 937 symval->size = es->st_size; 938 return 0; 939 } 940 if (ef->symtab == ef->ddbsymtab) 941 return ENOENT; 942 if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) { 943 symval->name = ef->ddbstrtab + es->st_name; 944 symval->value = (caddr_t) ef->address + es->st_value; 945 symval->size = es->st_size; 946 return 0; 947 } 948 return ENOENT; 949} 950 951static int 952link_elf_search_symbol(linker_file_t lf, caddr_t value, 953 c_linker_sym_t* sym, long* diffp) 954{ 955 elf_file_t ef = lf->priv; 956 u_long off = (uintptr_t) value; 957 u_long diff = off; 958 const Elf_Sym* es; 959 const Elf_Sym* best = 0; 960 int i; 961 962 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 963 if (es->st_name == 0) 964 continue; 965 if (off >= es->st_value) { 966 if (off - es->st_value < diff) { 967 diff = off - es->st_value; 968 best = es; 969 if (diff == 0) 970 break; 971 } else if (off - es->st_value == diff) { 972 best = es; 973 } 974 } 975 } 976 if (best == 0) 977 *diffp = off; 978 else 979 *diffp = diff; 980 *sym = (c_linker_sym_t) best; 981 982 return 0; 983} 984