Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/link_elf.c
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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 * $FreeBSD$ 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 #include <vm/vm_param.h> 42 #include <vm/vm_zone.h> 43 #include <sys/lock.h> 44 #ifdef SPARSE_MAPPING 45 #include <vm/vm_object.h> 46 #include <vm/vm_kern.h> 47 #include <vm/vm_extern.h> 48 #endif 49 #include <vm/pmap.h> 50 #include <vm/vm_map.h> 51 52 static int link_elf_load_module(const char*, linker_file_t*); 53 static int link_elf_load_file(const char*, linker_file_t*); 54 static int link_elf_lookup_symbol(linker_file_t, const char*, 55 c_linker_sym_t*); 56 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*); 57 static int link_elf_search_symbol(linker_file_t, caddr_t value, 58 c_linker_sym_t* sym, long* diffp); 59 60 static void link_elf_unload_file(linker_file_t); 61 static void link_elf_unload_module(linker_file_t); 62 63 static struct linker_class_ops link_elf_class_ops = { 64 link_elf_load_module, 65 }; 66 67 static struct linker_file_ops link_elf_file_ops = { 68 link_elf_lookup_symbol, 69 link_elf_symbol_values, 70 link_elf_search_symbol, 71 link_elf_unload_file, 72 }; 73 74 static struct linker_file_ops link_elf_module_ops = { 75 link_elf_lookup_symbol, 76 link_elf_symbol_values, 77 link_elf_search_symbol, 78 link_elf_unload_module, 79 }; 80 typedef struct elf_file { 81 caddr_t address; /* Relocation address */ 82 #ifdef SPARSE_MAPPING 83 vm_object_t object; /* VM object to hold file pages */ 84 #endif 85 const Elf_Dyn* dynamic; /* Symbol table etc. */ 86 Elf_Off nbuckets; /* DT_HASH info */ 87 Elf_Off nchains; 88 const Elf_Off* buckets; 89 const Elf_Off* chains; 90 caddr_t hash; 91 caddr_t strtab; /* DT_STRTAB */ 92 int strsz; /* DT_STRSZ */ 93 const Elf_Sym* symtab; /* DT_SYMTAB */ 94 Elf_Addr* got; /* DT_PLTGOT */ 95 const Elf_Rel* pltrel; /* DT_JMPREL */ 96 int pltrelsize; /* DT_PLTRELSZ */ 97 const Elf_Rela* pltrela; /* DT_JMPREL */ 98 int pltrelasize; /* DT_PLTRELSZ */ 99 const Elf_Rel* rel; /* DT_REL */ 100 int relsize; /* DT_RELSZ */ 101 const Elf_Rela* rela; /* DT_RELA */ 102 int relasize; /* DT_RELASZ */ 103 caddr_t modptr; 104 const Elf_Sym* ddbsymtab; /* The symbol table we are using */ 105 long ddbsymcnt; /* Number of symbols */ 106 caddr_t ddbstrtab; /* String table */ 107 long ddbstrcnt; /* number of bytes in string table */ 108 caddr_t symbase; /* malloc'ed symbold base */ 109 caddr_t strbase; /* malloc'ed string base */ 110 } *elf_file_t; 111 112 static int parse_dynamic(linker_file_t lf); 113 static int load_dependancies(linker_file_t lf); 114 static int relocate_file(linker_file_t lf); 115 static int parse_module_symbols(linker_file_t lf); 116 117 /* 118 * The kernel symbol table starts here. 119 */ 120 extern struct _dynamic _DYNAMIC; 121 122 static void 123 link_elf_init(void* arg) 124 { 125 #ifdef __ELF__ 126 Elf_Dyn *dp; 127 caddr_t modptr, baseptr, sizeptr; 128 elf_file_t ef; 129 char *modname; 130 #endif 131 132 #if ELF_TARG_CLASS == ELFCLASS32 133 linker_add_class("elf32", NULL, &link_elf_class_ops); 134 #else 135 linker_add_class("elf64", NULL, &link_elf_class_ops); 136 #endif 137 138 #ifdef __ELF__ 139 dp = (Elf_Dyn*) &_DYNAMIC; 140 if (dp) { 141 ef = malloc(sizeof(struct elf_file), M_LINKER, M_NOWAIT); 142 if (ef == NULL) 143 panic("link_elf_init: Can't create linker structures for kernel"); 144 bzero(ef, sizeof(*ef)); 145 146 ef->address = 0; 147 #ifdef SPARSE_MAPPING 148 ef->object = 0; 149 #endif 150 ef->dynamic = dp; 151 modname = NULL; 152 modptr = preload_search_by_type("elf kernel"); 153 if (modptr) 154 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 155 if (modname == NULL) 156 modname = "kernel"; 157 linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops); 158 if (linker_kernel_file == NULL) 159 panic("link_elf_init: Can't create linker structures for kernel"); 160 parse_dynamic(linker_kernel_file); 161 linker_kernel_file->address = (caddr_t) KERNBASE; 162 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address; 163 164 if (modptr) { 165 ef->modptr = modptr; 166 baseptr = preload_search_info(modptr, MODINFO_ADDR); 167 if (baseptr) 168 linker_kernel_file->address = *(caddr_t *)baseptr; 169 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 170 if (sizeptr) 171 linker_kernel_file->size = *(size_t *)sizeptr; 172 } 173 (void)parse_module_symbols(linker_kernel_file); 174 linker_current_file = linker_kernel_file; 175 linker_kernel_file->flags |= LINKER_FILE_LINKED; 176 } 177 #endif 178 } 179 180 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0); 181 182 static int 183 parse_module_symbols(linker_file_t lf) 184 { 185 elf_file_t ef = lf->priv; 186 caddr_t pointer; 187 caddr_t ssym, esym, base; 188 caddr_t strtab; 189 int strcnt; 190 Elf_Sym* symtab; 191 int symcnt; 192 193 if (ef->modptr == NULL) 194 return 0; 195 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 196 if (pointer == NULL) 197 return 0; 198 ssym = *(caddr_t *)pointer; 199 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 200 if (pointer == NULL) 201 return 0; 202 esym = *(caddr_t *)pointer; 203 204 base = ssym; 205 206 symcnt = *(long *)base; 207 base += sizeof(long); 208 symtab = (Elf_Sym *)base; 209 base += roundup(symcnt, sizeof(long)); 210 211 if (base > esym || base < ssym) { 212 printf("Symbols are corrupt!\n"); 213 return EINVAL; 214 } 215 216 strcnt = *(long *)base; 217 base += sizeof(long); 218 strtab = base; 219 base += roundup(strcnt, sizeof(long)); 220 221 if (base > esym || base < ssym) { 222 printf("Symbols are corrupt!\n"); 223 return EINVAL; 224 } 225 226 ef->ddbsymtab = symtab; 227 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 228 ef->ddbstrtab = strtab; 229 ef->ddbstrcnt = strcnt; 230 231 return 0; 232 } 233 234 static int 235 parse_dynamic(linker_file_t lf) 236 { 237 elf_file_t ef = lf->priv; 238 const Elf_Dyn *dp; 239 int plttype = DT_REL; 240 241 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 242 switch (dp->d_tag) { 243 case DT_HASH: 244 { 245 /* From src/libexec/rtld-elf/rtld.c */ 246 const Elf_Off *hashtab = (const Elf_Off *) 247 (ef->address + dp->d_un.d_ptr); 248 ef->nbuckets = hashtab[0]; 249 ef->nchains = hashtab[1]; 250 ef->buckets = hashtab + 2; 251 ef->chains = ef->buckets + ef->nbuckets; 252 break; 253 } 254 case DT_STRTAB: 255 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 256 break; 257 case DT_STRSZ: 258 ef->strsz = dp->d_un.d_val; 259 break; 260 case DT_SYMTAB: 261 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 262 break; 263 case DT_SYMENT: 264 if (dp->d_un.d_val != sizeof(Elf_Sym)) 265 return ENOEXEC; 266 break; 267 case DT_PLTGOT: 268 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 269 break; 270 case DT_REL: 271 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 272 break; 273 case DT_RELSZ: 274 ef->relsize = dp->d_un.d_val; 275 break; 276 case DT_RELENT: 277 if (dp->d_un.d_val != sizeof(Elf_Rel)) 278 return ENOEXEC; 279 break; 280 case DT_JMPREL: 281 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 282 break; 283 case DT_PLTRELSZ: 284 ef->pltrelsize = dp->d_un.d_val; 285 break; 286 case DT_RELA: 287 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 288 break; 289 case DT_RELASZ: 290 ef->relasize = dp->d_un.d_val; 291 break; 292 case DT_RELAENT: 293 if (dp->d_un.d_val != sizeof(Elf_Rela)) 294 return ENOEXEC; 295 break; 296 case DT_PLTREL: 297 plttype = dp->d_un.d_val; 298 if (plttype != DT_REL && plttype != DT_RELA) 299 return ENOEXEC; 300 break; 301 } 302 } 303 304 if (plttype == DT_RELA) { 305 ef->pltrela = (const Elf_Rela *) ef->pltrel; 306 ef->pltrel = NULL; 307 ef->pltrelasize = ef->pltrelsize; 308 ef->pltrelsize = 0; 309 } 310 311 ef->ddbsymtab = ef->symtab; 312 ef->ddbsymcnt = ef->nchains; 313 ef->ddbstrtab = ef->strtab; 314 ef->ddbstrcnt = ef->strsz; 315 316 return 0; 317 } 318 319 static void 320 link_elf_error(const char *s) 321 { 322 printf("kldload: %s\n", s); 323 } 324 325 static int 326 link_elf_load_module(const char *filename, linker_file_t *result) 327 { 328 caddr_t modptr, baseptr, sizeptr, dynptr; 329 char *type; 330 elf_file_t ef; 331 linker_file_t lf; 332 int error; 333 vm_offset_t dp; 334 335 /* Look to see if we have the module preloaded */ 336 modptr = preload_search_by_name(filename); 337 if (modptr == NULL) 338 return (link_elf_load_file(filename, result)); 339 340 /* It's preloaded, check we can handle it and collect information */ 341 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 342 baseptr = preload_search_info(modptr, MODINFO_ADDR); 343 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 344 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 345 if (type == NULL || strcmp(type, "elf module") != 0) 346 return (EFTYPE); 347 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 348 return (EINVAL); 349 350 ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK); 351 if (ef == NULL) 352 return (ENOMEM); 353 bzero(ef, sizeof(*ef)); 354 ef->modptr = modptr; 355 ef->address = *(caddr_t *)baseptr; 356 #ifdef SPARSE_MAPPING 357 ef->object = 0; 358 #endif 359 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 360 ef->dynamic = (Elf_Dyn *)dp; 361 lf = linker_make_file(filename, ef, &link_elf_module_ops); 362 if (lf == NULL) { 363 free(ef, M_LINKER); 364 return ENOMEM; 365 } 366 lf->address = ef->address; 367 lf->size = *(size_t *)sizeptr; 368 369 error = parse_dynamic(lf); 370 if (error) { 371 linker_file_unload(lf); 372 return error; 373 } 374 error = load_dependancies(lf); 375 if (error) { 376 linker_file_unload(lf); 377 return error; 378 } 379 error = relocate_file(lf); 380 if (error) { 381 linker_file_unload(lf); 382 return error; 383 } 384 (void)parse_module_symbols(lf); 385 lf->flags |= LINKER_FILE_LINKED; 386 *result = lf; 387 return (0); 388 } 389 390 static int 391 link_elf_load_file(const char* filename, linker_file_t* result) 392 { 393 struct nameidata nd; 394 struct proc* p = curproc; /* XXX */ 395 Elf_Ehdr *hdr; 396 caddr_t firstpage; 397 int nbytes, i; 398 Elf_Phdr *phdr; 399 Elf_Phdr *phlimit; 400 Elf_Phdr *segs[2]; 401 int nsegs; 402 Elf_Phdr *phdyn; 403 Elf_Phdr *phphdr; 404 caddr_t mapbase; 405 size_t mapsize; 406 Elf_Off base_offset; 407 Elf_Addr base_vaddr; 408 Elf_Addr base_vlimit; 409 int error = 0; 410 int resid; 411 elf_file_t ef; 412 linker_file_t lf; 413 char *pathname; 414 Elf_Shdr *shdr; 415 int symtabindex; 416 int symstrindex; 417 int symcnt; 418 int strcnt; 419 420 shdr = NULL; 421 lf = NULL; 422 423 pathname = linker_search_path(filename); 424 if (pathname == NULL) 425 return ENOENT; 426 427 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, pathname, p); 428 error = vn_open(&nd, FREAD, 0); 429 free(pathname, M_LINKER); 430 if (error) 431 return error; 432 NDFREE(&nd, NDF_ONLY_PNBUF); 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; 677 678 nosyms: 679 680 *result = lf; 681 682 out: 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 } 694 695 static void 696 link_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 } 719 720 static void 721 link_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 } 730 731 static int 732 load_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 } 760 761 out: 762 return error; 763 } 764 765 static const char * 766 symbol_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 } 776 777 static int 778 relocate_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 */ 850 static unsigned long 851 elf_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 } 865 866 int 867 link_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 } 927 928 static int 929 link_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 } 950 951 static int 952 link_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) (void *) value; 957 u_long diff = off; 958 u_long st_value; 959 const Elf_Sym* es; 960 const Elf_Sym* best = 0; 961 int i; 962 963 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 964 if (es->st_name == 0) 965 continue; 966 st_value = es->st_value + (uintptr_t) (void *) ef->address; 967 if (off >= st_value) { 968 if (off - st_value < diff) { 969 diff = off - st_value; 970 best = es; 971 if (diff == 0) 972 break; 973 } else if (off - st_value == diff) { 974 best = es; 975 } 976 } 977 } 978 if (best == 0) 979 *diffp = off; 980 else 981 *diffp = diff; 982 *sym = (c_linker_sym_t) best; 983 984 return 0; 985 }
Cache object: 11d6e39f4822f895a3ae3aebfb4d9cc4
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