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_prot.h> 42 #include <vm/vm_param.h> 43 #include <sys/lock.h> 44 #include <vm/vm_object.h> 45 #include <vm/vm_kern.h> 46 #include <vm/vm_extern.h> 47 #include <vm/pmap.h> 48 #include <vm/vm_map.h> 49 50 static int link_elf_load_module(const char*, linker_file_t*); 51 static int link_elf_load_file(const char*, linker_file_t*); 52 static int link_elf_lookup_symbol(linker_file_t, const char*, 53 linker_sym_t*); 54 static int link_elf_symbol_values(linker_file_t, linker_sym_t, linker_symval_t*); 55 static int link_elf_search_symbol(linker_file_t, caddr_t value, 56 linker_sym_t* sym, long* diffp); 57 58 static void link_elf_unload_file(linker_file_t); 59 static void link_elf_unload_module(linker_file_t); 60 61 static struct linker_class_ops link_elf_class_ops = { 62 link_elf_load_module, 63 }; 64 65 static struct linker_file_ops link_elf_file_ops = { 66 link_elf_lookup_symbol, 67 link_elf_symbol_values, 68 link_elf_search_symbol, 69 link_elf_unload_file, 70 }; 71 72 static struct linker_file_ops link_elf_module_ops = { 73 link_elf_lookup_symbol, 74 link_elf_symbol_values, 75 link_elf_search_symbol, 76 link_elf_unload_module, 77 }; 78 typedef struct elf_file { 79 caddr_t address; /* Relocation address */ 80 #ifdef SPARSE_MAPPING 81 vm_object_t object; /* VM object to hold file pages */ 82 #endif 83 const Elf_Dyn* dynamic; /* Symbol table etc. */ 84 Elf_Off nbuckets; /* DT_HASH info */ 85 Elf_Off nchains; 86 const Elf_Off* buckets; 87 const Elf_Off* chains; 88 caddr_t hash; 89 caddr_t strtab; /* DT_STRTAB */ 90 int strsz; /* DT_STRSZ */ 91 const Elf_Sym* symtab; /* DT_SYMTAB */ 92 Elf_Addr* got; /* DT_PLTGOT */ 93 const Elf_Rel* pltrel; /* DT_JMPREL */ 94 int pltrelsize; /* DT_PLTRELSZ */ 95 const Elf_Rela* pltrela; /* DT_JMPREL */ 96 int pltrelasize; /* DT_PLTRELSZ */ 97 const Elf_Rel* rel; /* DT_REL */ 98 int relsize; /* DT_RELSZ */ 99 const Elf_Rela* rela; /* DT_RELA */ 100 int relasize; /* DT_RELASZ */ 101 caddr_t modptr; 102 const Elf_Sym* ddbsymtab; /* The symbol table we are using */ 103 long ddbsymcnt; /* Number of symbols */ 104 caddr_t ddbstrtab; /* String table */ 105 long ddbstrcnt; /* number of bytes in string table */ 106 caddr_t symbase; /* malloc'ed symbold base */ 107 caddr_t strbase; /* malloc'ed string base */ 108 } *elf_file_t; 109 110 static int parse_dynamic(linker_file_t lf); 111 static int load_dependancies(linker_file_t lf); 112 static int relocate_file(linker_file_t lf); 113 static int parse_module_symbols(linker_file_t lf); 114 115 /* 116 * The kernel symbol table starts here. 117 */ 118 extern struct _dynamic _DYNAMIC; 119 120 static void 121 link_elf_init(void* arg) 122 { 123 #ifdef __ELF__ 124 Elf_Dyn *dp; 125 caddr_t modptr, baseptr, sizeptr; 126 elf_file_t ef; 127 char *modname; 128 #endif 129 130 #if ELF_TARG_CLASS == ELFCLASS32 131 linker_add_class("elf32", NULL, &link_elf_class_ops); 132 #else 133 linker_add_class("elf64", NULL, &link_elf_class_ops); 134 #endif 135 136 #ifdef __ELF__ 137 dp = (Elf_Dyn*) &_DYNAMIC; 138 if (dp) { 139 ef = malloc(sizeof(struct elf_file), M_LINKER, M_NOWAIT); 140 if (ef == NULL) 141 panic("link_elf_init: Can't create linker structures for kernel"); 142 bzero(ef, sizeof(*ef)); 143 144 ef->address = 0; 145 #ifdef SPARSE_MAPPING 146 ef->object = 0; 147 #endif 148 ef->dynamic = dp; 149 modname = NULL; 150 modptr = preload_search_by_type("elf kernel"); 151 if (modptr) 152 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 153 if (modname == NULL) 154 modname = "kernel"; 155 linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops); 156 if (linker_kernel_file == NULL) 157 panic("link_elf_init: Can't create linker structures for kernel"); 158 parse_dynamic(linker_kernel_file); 159 /* Sigh, magic constants. */ 160 #ifdef __alpha__ 161 linker_kernel_file->address = (caddr_t) 0xfffffc0000300000; 162 #else 163 linker_kernel_file->address = (caddr_t) 0xf0100000; 164 #endif 165 linker_kernel_file->size = -(long)linker_kernel_file->address; 166 167 if (modptr) { 168 ef->modptr = modptr; 169 baseptr = preload_search_info(modptr, MODINFO_ADDR); 170 if (baseptr) 171 linker_kernel_file->address = *(caddr_t *)baseptr; 172 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 173 if (sizeptr) 174 linker_kernel_file->size = *(size_t *)sizeptr; 175 } 176 (void)parse_module_symbols(linker_kernel_file); 177 linker_current_file = linker_kernel_file; 178 linker_kernel_file->flags |= LINKER_FILE_LINKED; 179 } 180 #endif 181 } 182 183 SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0); 184 185 static int 186 parse_module_symbols(linker_file_t lf) 187 { 188 elf_file_t ef = lf->priv; 189 caddr_t pointer; 190 caddr_t ssym, esym, base; 191 caddr_t strtab; 192 int strcnt; 193 Elf_Sym* symtab; 194 int symcnt; 195 196 if (ef->modptr == NULL) 197 return 0; 198 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 199 if (pointer == NULL) 200 return 0; 201 ssym = *(caddr_t *)pointer; 202 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 203 if (pointer == NULL) 204 return 0; 205 esym = *(caddr_t *)pointer; 206 207 base = ssym; 208 209 symcnt = *(long *)base; 210 base += sizeof(long); 211 symtab = (Elf_Sym *)base; 212 base += roundup(symcnt, sizeof(long)); 213 214 if (base > esym || base < ssym) { 215 printf("Symbols are corrupt!\n"); 216 return EINVAL; 217 } 218 219 strcnt = *(long *)base; 220 base += sizeof(long); 221 strtab = base; 222 base += roundup(strcnt, sizeof(long)); 223 224 if (base > esym || base < ssym) { 225 printf("Symbols are corrupt!\n"); 226 return EINVAL; 227 } 228 229 ef->ddbsymtab = symtab; 230 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 231 ef->ddbstrtab = strtab; 232 ef->ddbstrcnt = strcnt; 233 234 return 0; 235 } 236 237 static int 238 parse_dynamic(linker_file_t lf) 239 { 240 elf_file_t ef = lf->priv; 241 const Elf_Dyn *dp; 242 int plttype = DT_REL; 243 244 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 245 switch (dp->d_tag) { 246 case DT_HASH: 247 { 248 /* From src/libexec/rtld-elf/rtld.c */ 249 const Elf_Off *hashtab = (const Elf_Off *) 250 (ef->address + dp->d_un.d_ptr); 251 ef->nbuckets = hashtab[0]; 252 ef->nchains = hashtab[1]; 253 ef->buckets = hashtab + 2; 254 ef->chains = ef->buckets + ef->nbuckets; 255 break; 256 } 257 case DT_STRTAB: 258 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 259 break; 260 case DT_STRSZ: 261 ef->strsz = dp->d_un.d_val; 262 break; 263 case DT_SYMTAB: 264 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 265 break; 266 case DT_SYMENT: 267 if (dp->d_un.d_val != sizeof(Elf_Sym)) 268 return ENOEXEC; 269 break; 270 case DT_PLTGOT: 271 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 272 break; 273 case DT_REL: 274 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 275 break; 276 case DT_RELSZ: 277 ef->relsize = dp->d_un.d_val; 278 break; 279 case DT_RELENT: 280 if (dp->d_un.d_val != sizeof(Elf_Rel)) 281 return ENOEXEC; 282 break; 283 case DT_JMPREL: 284 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 285 break; 286 case DT_PLTRELSZ: 287 ef->pltrelsize = dp->d_un.d_val; 288 break; 289 case DT_RELA: 290 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 291 break; 292 case DT_RELASZ: 293 ef->relasize = dp->d_un.d_val; 294 break; 295 case DT_RELAENT: 296 if (dp->d_un.d_val != sizeof(Elf_Rela)) 297 return ENOEXEC; 298 break; 299 case DT_PLTREL: 300 plttype = dp->d_un.d_val; 301 if (plttype != DT_REL && plttype != DT_RELA) 302 return ENOEXEC; 303 break; 304 } 305 } 306 307 if (plttype == DT_RELA) { 308 ef->pltrela = (const Elf_Rela *) ef->pltrel; 309 ef->pltrel = NULL; 310 ef->pltrelasize = ef->pltrelsize; 311 ef->pltrelsize = 0; 312 } 313 314 ef->ddbsymtab = ef->symtab; 315 ef->ddbsymcnt = ef->nchains; 316 ef->ddbstrtab = ef->strtab; 317 ef->ddbstrcnt = ef->strsz; 318 319 return 0; 320 } 321 322 static void 323 link_elf_error(const char *s) 324 { 325 printf("kldload: %s\n", s); 326 } 327 328 static int 329 link_elf_load_module(const char *filename, linker_file_t *result) 330 { 331 caddr_t modptr, baseptr, sizeptr, dynptr; 332 char *type; 333 elf_file_t ef; 334 linker_file_t lf; 335 int error; 336 vm_offset_t dp; 337 338 /* Look to see if we have the module preloaded */ 339 modptr = preload_search_by_name(filename); 340 if (modptr == NULL) 341 return (link_elf_load_file(filename, result)); 342 343 /* It's preloaded, check we can handle it and collect information */ 344 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 345 baseptr = preload_search_info(modptr, MODINFO_ADDR); 346 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 347 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 348 if (type == NULL || strcmp(type, "elf module") != 0) 349 return (EFTYPE); 350 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 351 return (EINVAL); 352 353 ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK); 354 if (ef == NULL) 355 return (ENOMEM); 356 bzero(ef, sizeof(*ef)); 357 ef->modptr = modptr; 358 ef->address = *(caddr_t *)baseptr; 359 #ifdef SPARSE_MAPPING 360 ef->object = 0; 361 #endif 362 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 363 ef->dynamic = (Elf_Dyn *)dp; 364 lf = linker_make_file(filename, ef, &link_elf_module_ops); 365 if (lf == NULL) { 366 free(ef, M_LINKER); 367 return ENOMEM; 368 } 369 lf->address = ef->address; 370 lf->size = *(size_t *)sizeptr; 371 372 error = parse_dynamic(lf); 373 if (error) { 374 linker_file_unload(lf); 375 return error; 376 } 377 error = load_dependancies(lf); 378 if (error) { 379 linker_file_unload(lf); 380 return error; 381 } 382 error = relocate_file(lf); 383 if (error) { 384 linker_file_unload(lf); 385 return error; 386 } 387 (void)parse_module_symbols(lf); 388 lf->flags |= LINKER_FILE_LINKED; 389 *result = lf; 390 return (0); 391 } 392 393 static int 394 link_elf_load_file(const char* filename, linker_file_t* result) 395 { 396 struct nameidata nd; 397 struct proc* p = curproc; /* XXX */ 398 Elf_Ehdr *hdr; 399 caddr_t firstpage; 400 int nbytes, i; 401 Elf_Phdr *phdr; 402 Elf_Phdr *phlimit; 403 Elf_Phdr *segs[2]; 404 int nsegs; 405 Elf_Phdr *phdyn; 406 Elf_Phdr *phphdr; 407 caddr_t mapbase; 408 size_t mapsize; 409 Elf_Off base_offset; 410 Elf_Addr base_vaddr; 411 Elf_Addr base_vlimit; 412 int error = 0; 413 int resid; 414 elf_file_t ef; 415 linker_file_t lf; 416 char *pathname; 417 Elf_Shdr *shdr; 418 int symtabindex; 419 int symstrindex; 420 int symcnt; 421 int strcnt; 422 423 shdr = NULL; 424 lf = NULL; 425 426 pathname = linker_search_path(filename); 427 if (pathname == NULL) 428 return ENOENT; 429 430 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, pathname, p); 431 error = vn_open(&nd, FREAD, 0); 432 free(pathname, M_LINKER); 433 if (error) 434 return error; 435 436 /* 437 * Read the elf header from the file. 438 */ 439 firstpage = malloc(PAGE_SIZE, M_LINKER, M_WAITOK); 440 if (firstpage == NULL) { 441 error = ENOMEM; 442 goto out; 443 } 444 hdr = (Elf_Ehdr *)firstpage; 445 error = vn_rdwr(UIO_READ, nd.ni_vp, firstpage, PAGE_SIZE, 0, 446 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p); 447 nbytes = PAGE_SIZE - resid; 448 if (error) 449 goto out; 450 451 if (!IS_ELF(*hdr)) { 452 error = ENOEXEC; 453 goto out; 454 } 455 456 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 457 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 458 link_elf_error("Unsupported file layout"); 459 error = ENOEXEC; 460 goto out; 461 } 462 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 463 || hdr->e_version != EV_CURRENT) { 464 link_elf_error("Unsupported file version"); 465 error = ENOEXEC; 466 goto out; 467 } 468 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 469 link_elf_error("Unsupported file type"); 470 error = ENOEXEC; 471 goto out; 472 } 473 if (hdr->e_machine != ELF_TARG_MACH) { 474 link_elf_error("Unsupported machine"); 475 error = ENOEXEC; 476 goto out; 477 } 478 479 /* 480 * We rely on the program header being in the first page. This is 481 * not strictly required by the ABI specification, but it seems to 482 * always true in practice. And, it simplifies things considerably. 483 */ 484 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 485 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 486 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 487 link_elf_error("Unreadable program headers"); 488 489 /* 490 * Scan the program header entries, and save key information. 491 * 492 * We rely on there being exactly two load segments, text and data, 493 * in that order. 494 */ 495 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 496 phlimit = phdr + hdr->e_phnum; 497 nsegs = 0; 498 phdyn = NULL; 499 phphdr = NULL; 500 while (phdr < phlimit) { 501 switch (phdr->p_type) { 502 503 case PT_LOAD: 504 if (nsegs == 2) { 505 link_elf_error("Too many sections"); 506 error = ENOEXEC; 507 goto out; 508 } 509 segs[nsegs] = phdr; 510 ++nsegs; 511 break; 512 513 case PT_PHDR: 514 phphdr = phdr; 515 break; 516 517 case PT_DYNAMIC: 518 phdyn = phdr; 519 break; 520 } 521 522 ++phdr; 523 } 524 if (phdyn == NULL) { 525 link_elf_error("Object is not dynamically-linked"); 526 error = ENOEXEC; 527 goto out; 528 } 529 530 /* 531 * Allocate the entire address space of the object, to stake out our 532 * contiguous region, and to establish the base address for relocation. 533 */ 534 base_offset = trunc_page(segs[0]->p_offset); 535 base_vaddr = trunc_page(segs[0]->p_vaddr); 536 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); 537 mapsize = base_vlimit - base_vaddr; 538 539 ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK); 540 bzero(ef, sizeof(*ef)); 541 #ifdef SPARSE_MAPPING 542 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 543 if (ef->object == NULL) { 544 free(ef, M_LINKER); 545 error = ENOMEM; 546 goto out; 547 } 548 vm_object_reference(ef->object); 549 ef->address = (caddr_t) vm_map_min(kernel_map); 550 error = vm_map_find(kernel_map, ef->object, 0, 551 (vm_offset_t *) &ef->address, 552 mapsize, 1, 553 VM_PROT_ALL, VM_PROT_ALL, 0); 554 if (error) { 555 vm_object_deallocate(ef->object); 556 free(ef, M_LINKER); 557 goto out; 558 } 559 #else 560 ef->address = malloc(mapsize, M_LINKER, M_WAITOK); 561 #endif 562 mapbase = ef->address; 563 564 /* 565 * Read the text and data sections and zero the bss. 566 */ 567 for (i = 0; i < 2; i++) { 568 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 569 error = vn_rdwr(UIO_READ, nd.ni_vp, 570 segbase, segs[i]->p_filesz, segs[i]->p_offset, 571 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p); 572 if (error) { 573 #ifdef SPARSE_MAPPING 574 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 575 (vm_offset_t) ef->address 576 + (ef->object->size << PAGE_SHIFT)); 577 vm_object_deallocate(ef->object); 578 #else 579 free(ef->address, M_LINKER); 580 #endif 581 free(ef, M_LINKER); 582 goto out; 583 } 584 bzero(segbase + segs[i]->p_filesz, 585 segs[i]->p_memsz - segs[i]->p_filesz); 586 587 #ifdef SPARSE_MAPPING 588 /* 589 * Wire down the pages 590 */ 591 vm_map_pageable(kernel_map, 592 (vm_offset_t) segbase, 593 (vm_offset_t) segbase + segs[i]->p_memsz, 594 FALSE); 595 #endif 596 } 597 598 ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 599 600 lf = linker_make_file(filename, ef, &link_elf_file_ops); 601 if (lf == NULL) { 602 #ifdef SPARSE_MAPPING 603 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 604 (vm_offset_t) ef->address 605 + (ef->object->size << PAGE_SHIFT)); 606 vm_object_deallocate(ef->object); 607 #else 608 free(ef->address, M_LINKER); 609 #endif 610 free(ef, M_LINKER); 611 error = ENOMEM; 612 goto out; 613 } 614 lf->address = ef->address; 615 lf->size = mapsize; 616 617 error = parse_dynamic(lf); 618 if (error) 619 goto out; 620 error = load_dependancies(lf); 621 if (error) 622 goto out; 623 error = relocate_file(lf); 624 if (error) 625 goto out; 626 627 /* Try and load the symbol table if it's present. (you can strip it!) */ 628 nbytes = hdr->e_shnum * hdr->e_shentsize; 629 if (nbytes == 0 || hdr->e_shoff == 0) 630 goto nosyms; 631 shdr = malloc(nbytes, M_LINKER, M_WAITOK); 632 if (shdr == NULL) { 633 error = ENOMEM; 634 goto out; 635 } 636 bzero(shdr, nbytes); 637 error = vn_rdwr(UIO_READ, nd.ni_vp, 638 (caddr_t)shdr, nbytes, hdr->e_shoff, 639 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p); 640 if (error) 641 goto out; 642 symtabindex = -1; 643 symstrindex = -1; 644 for (i = 0; i < hdr->e_shnum; i++) { 645 if (shdr[i].sh_type == SHT_SYMTAB) { 646 symtabindex = i; 647 symstrindex = shdr[i].sh_link; 648 } 649 } 650 if (symtabindex < 0 || symstrindex < 0) 651 goto nosyms; 652 653 symcnt = shdr[symtabindex].sh_size; 654 ef->symbase = malloc(symcnt, M_LINKER, M_WAITOK); 655 strcnt = shdr[symstrindex].sh_size; 656 ef->strbase = malloc(strcnt, M_LINKER, M_WAITOK); 657 658 if (ef->symbase == NULL || ef->strbase == NULL) { 659 error = ENOMEM; 660 goto out; 661 } 662 error = vn_rdwr(UIO_READ, nd.ni_vp, 663 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 664 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p); 665 if (error) 666 goto out; 667 error = vn_rdwr(UIO_READ, nd.ni_vp, 668 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 669 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p); 670 if (error) 671 goto out; 672 673 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 674 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 675 ef->ddbstrcnt = strcnt; 676 ef->ddbstrtab = ef->strbase; 677 678 lf->flags |= LINKER_FILE_LINKED; 679 680 nosyms: 681 682 *result = lf; 683 684 out: 685 if (error && lf) 686 linker_file_unload(lf); 687 if (shdr) 688 free(shdr, M_LINKER); 689 if (firstpage) 690 free(firstpage, M_LINKER); 691 VOP_UNLOCK(nd.ni_vp, 0, p); 692 vn_close(nd.ni_vp, FREAD, p->p_ucred, p); 693 694 return error; 695 } 696 697 static void 698 link_elf_unload_file(linker_file_t file) 699 { 700 elf_file_t ef = file->priv; 701 702 if (ef) { 703 #ifdef SPARSE_MAPPING 704 if (ef->object) { 705 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 706 (vm_offset_t) ef->address 707 + (ef->object->size << PAGE_SHIFT)); 708 vm_object_deallocate(ef->object); 709 } 710 #else 711 if (ef->address) 712 free(ef->address, M_LINKER); 713 #endif 714 if (ef->symbase) 715 free(ef->symbase, M_LINKER); 716 if (ef->strbase) 717 free(ef->strbase, M_LINKER); 718 free(ef, M_LINKER); 719 } 720 } 721 722 static void 723 link_elf_unload_module(linker_file_t file) 724 { 725 elf_file_t ef = file->priv; 726 727 if (ef) 728 free(ef, M_LINKER); 729 if (file->filename) 730 preload_delete_name(file->filename); 731 } 732 733 static int 734 load_dependancies(linker_file_t lf) 735 { 736 elf_file_t ef = lf->priv; 737 linker_file_t lfdep; 738 char* name; 739 const Elf_Dyn *dp; 740 int error = 0; 741 742 /* 743 * All files are dependant on /kernel. 744 */ 745 if (linker_kernel_file) { 746 linker_kernel_file->refs++; 747 linker_file_add_dependancy(lf, linker_kernel_file); 748 } 749 750 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 751 if (dp->d_tag == DT_NEEDED) { 752 name = ef->strtab + dp->d_un.d_val; 753 754 error = linker_load_file(name, &lfdep); 755 if (error) 756 goto out; 757 error = linker_file_add_dependancy(lf, lfdep); 758 if (error) 759 goto out; 760 } 761 } 762 763 out: 764 return error; 765 } 766 767 static const char * 768 symbol_name(elf_file_t ef, Elf_Word r_info) 769 { 770 const Elf_Sym *ref; 771 772 if (ELF_R_SYM(r_info)) { 773 ref = ef->symtab + ELF_R_SYM(r_info); 774 return ef->strtab + ref->st_name; 775 } else 776 return NULL; 777 } 778 779 static int 780 relocate_file(linker_file_t lf) 781 { 782 elf_file_t ef = lf->priv; 783 const Elf_Rel *rellim; 784 const Elf_Rel *rel; 785 const Elf_Rela *relalim; 786 const Elf_Rela *rela; 787 const char *symname; 788 789 /* Perform relocations without addend if there are any: */ 790 rel = ef->rel; 791 if (rel) { 792 rellim = (const Elf_Rel *) ((caddr_t) ef->rel + ef->relsize); 793 while (rel < rellim) { 794 symname = symbol_name(ef, rel->r_info); 795 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) { 796 printf("link_elf: symbol %s undefined\n", symname); 797 return ENOENT; 798 } 799 rel++; 800 } 801 } 802 803 /* Perform relocations with addend if there are any: */ 804 rela = ef->rela; 805 if (rela) { 806 relalim = (const Elf_Rela *) ((caddr_t) ef->rela + ef->relasize); 807 while (rela < relalim) { 808 symname = symbol_name(ef, rela->r_info); 809 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) { 810 printf("link_elf: symbol %s undefined\n", symname); 811 return ENOENT; 812 } 813 rela++; 814 } 815 } 816 817 /* Perform PLT relocations without addend if there are any: */ 818 rel = ef->pltrel; 819 if (rel) { 820 rellim = (const Elf_Rel *) ((caddr_t) ef->pltrel + ef->pltrelsize); 821 while (rel < rellim) { 822 symname = symbol_name(ef, rel->r_info); 823 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) { 824 printf("link_elf: symbol %s undefined\n", symname); 825 return ENOENT; 826 } 827 rel++; 828 } 829 } 830 831 /* Perform relocations with addend if there are any: */ 832 rela = ef->pltrela; 833 if (rela) { 834 relalim = (const Elf_Rela *) ((caddr_t) ef->pltrela + ef->pltrelasize); 835 while (rela < relalim) { 836 symname = symbol_name(ef, rela->r_info); 837 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) { 838 printf("link_elf: symbol %s undefined\n", symname); 839 return ENOENT; 840 } 841 rela++; 842 } 843 } 844 845 return 0; 846 } 847 848 /* 849 * Hash function for symbol table lookup. Don't even think about changing 850 * this. It is specified by the System V ABI. 851 */ 852 static unsigned long 853 elf_hash(const char *name) 854 { 855 const unsigned char *p = (const unsigned char *) name; 856 unsigned long h = 0; 857 unsigned long g; 858 859 while (*p != '\0') { 860 h = (h << 4) + *p++; 861 if ((g = h & 0xf0000000) != 0) 862 h ^= g >> 24; 863 h &= ~g; 864 } 865 return h; 866 } 867 868 int 869 link_elf_lookup_symbol(linker_file_t lf, const char* name, linker_sym_t* sym) 870 { 871 elf_file_t ef = lf->priv; 872 unsigned long symnum; 873 const Elf_Sym* symp; 874 const char *strp; 875 unsigned long hash; 876 int i; 877 878 /* First, search hashed global symbols */ 879 hash = elf_hash(name); 880 symnum = ef->buckets[hash % ef->nbuckets]; 881 882 while (symnum != STN_UNDEF) { 883 if (symnum >= ef->nchains) { 884 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 885 return ENOENT; 886 } 887 888 symp = ef->symtab + symnum; 889 if (symp->st_name == 0) { 890 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 891 return ENOENT; 892 } 893 894 strp = ef->strtab + symp->st_name; 895 896 if (strcmp(name, strp) == 0) { 897 if (symp->st_shndx != SHN_UNDEF || 898 (symp->st_value != 0 && 899 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 900 *sym = (linker_sym_t) symp; 901 return 0; 902 } else 903 return ENOENT; 904 } 905 906 symnum = ef->chains[symnum]; 907 } 908 909 /* If we have not found it, look at the full table (if loaded) */ 910 if (ef->symtab == ef->ddbsymtab) 911 return ENOENT; 912 913 /* Exhaustive search */ 914 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 915 strp = ef->ddbstrtab + symp->st_name; 916 if (strcmp(name, strp) == 0) { 917 if (symp->st_shndx != SHN_UNDEF || 918 (symp->st_value != 0 && 919 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 920 *sym = (linker_sym_t) symp; 921 return 0; 922 } else 923 return ENOENT; 924 } 925 } 926 927 return ENOENT; 928 } 929 930 static int 931 link_elf_symbol_values(linker_file_t lf, linker_sym_t sym, linker_symval_t* symval) 932 { 933 elf_file_t ef = lf->priv; 934 Elf_Sym* es = (Elf_Sym*) sym; 935 936 if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) { 937 symval->name = ef->strtab + es->st_name; 938 symval->value = (caddr_t) ef->address + es->st_value; 939 symval->size = es->st_size; 940 return 0; 941 } 942 if (ef->symtab == ef->ddbsymtab) 943 return ENOENT; 944 if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) { 945 symval->name = ef->ddbstrtab + es->st_name; 946 symval->value = (caddr_t) ef->address + es->st_value; 947 symval->size = es->st_size; 948 return 0; 949 } 950 return ENOENT; 951 } 952 953 static int 954 link_elf_search_symbol(linker_file_t lf, caddr_t value, 955 linker_sym_t* sym, long* diffp) 956 { 957 elf_file_t ef = lf->priv; 958 u_long off = (u_long) value; 959 u_long diff = off; 960 const Elf_Sym* es; 961 const Elf_Sym* best = 0; 962 int i; 963 u_long st_value; 964 965 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 966 if (es->st_name == 0) 967 continue; 968 st_value = es->st_value + (u_long)ef->address; 969 if (off >= st_value) { 970 if (off - st_value < diff) { 971 diff = off - st_value; 972 best = es; 973 if (diff == 0) 974 break; 975 } else if (off - st_value == diff) { 976 best = es; 977 } 978 } 979 } 980 if (best == 0) 981 *diffp = off; 982 else 983 *diffp = diff; 984 *sym = (linker_sym_t) best; 985 986 return 0; 987 }
Cache object: 1644486243de0fefe84c256e4aebf11a
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