link_elf.c revision 40648
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 * $Id: link_elf.c,v 1.7 1998/10/16 03:55:00 peter Exp $ 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 50static int link_elf_load_module(const char*, linker_file_t*); 51static int link_elf_load_file(const char*, linker_file_t*); 52static int link_elf_lookup_symbol(linker_file_t, const char*, 53 linker_sym_t*); 54static int link_elf_symbol_values(linker_file_t, linker_sym_t, linker_symval_t*); 55static int link_elf_search_symbol(linker_file_t, caddr_t value, 56 linker_sym_t* sym, long* diffp); 57 58static void link_elf_unload_file(linker_file_t); 59static void link_elf_unload_module(linker_file_t); 60 61/* 62 * The file representing the currently running kernel. This contains 63 * the global symbol table. 64 */ 65 66linker_file_t linker_kernel_file; 67 68static struct linker_class_ops link_elf_class_ops = { 69 link_elf_load_module, 70}; 71 72static struct linker_file_ops link_elf_file_ops = { 73 link_elf_lookup_symbol, 74 link_elf_symbol_values, 75 link_elf_search_symbol, 76 link_elf_unload_file, 77}; 78 79static struct linker_file_ops link_elf_module_ops = { 80 link_elf_lookup_symbol, 81 link_elf_symbol_values, 82 link_elf_search_symbol, 83 link_elf_unload_module, 84}; 85typedef struct elf_file { 86 caddr_t address; /* Relocation address */ 87#ifdef SPARSE_MAPPING 88 vm_object_t object; /* VM object to hold file pages */ 89#endif 90 const Elf_Dyn* dynamic; /* Symbol table etc. */ 91 Elf_Off nbuckets; /* DT_HASH info */ 92 Elf_Off nchains; 93 const Elf_Off* buckets; 94 const Elf_Off* chains; 95 caddr_t hash; 96 caddr_t strtab; /* DT_STRTAB */ 97 int strsz; /* DT_STRSZ */ 98 const Elf_Sym* symtab; /* DT_SYMTAB */ 99 Elf_Addr* got; /* DT_PLTGOT */ 100 const Elf_Rel* pltrel; /* DT_JMPREL */ 101 int pltrelsize; /* DT_PLTRELSZ */ 102 const Elf_Rela* pltrela; /* DT_JMPREL */ 103 int pltrelasize; /* DT_PLTRELSZ */ 104 const Elf_Rel* rel; /* DT_REL */ 105 int relsize; /* DT_RELSZ */ 106 const Elf_Rela* rela; /* DT_RELA */ 107 int relasize; /* DT_RELASZ */ 108 caddr_t modptr; 109 const Elf_Sym* ddbsymtab; /* The symbol table we are using */ 110 long ddbsymcnt; /* Number of symbols */ 111 caddr_t ddbstrtab; /* String table */ 112 long ddbstrcnt; /* number of bytes in string table */ 113 caddr_t symbase; /* malloc'ed symbold base */ 114 caddr_t strbase; /* malloc'ed string base */ 115} *elf_file_t; 116 117static int parse_dynamic(linker_file_t lf); 118static int load_dependancies(linker_file_t lf); 119static int relocate_file(linker_file_t lf); 120static int parse_module_symbols(linker_file_t lf); 121 122/* 123 * The kernel symbol table starts here. 124 */ 125extern struct _dynamic _DYNAMIC; 126 127static void 128link_elf_init(void* arg) 129{ 130#ifdef __ELF__ 131 Elf_Dyn *dp; 132 caddr_t modptr, baseptr, sizeptr; 133 elf_file_t ef; 134 char *modname; 135#endif 136 137#if ELF_TARG_CLASS == ELFCLASS32 138 linker_add_class("elf32", NULL, &link_elf_class_ops); 139#else 140 linker_add_class("elf64", NULL, &link_elf_class_ops); 141#endif 142 143#ifdef __ELF__ 144 dp = (Elf_Dyn*) &_DYNAMIC; 145 if (dp) { 146 ef = malloc(sizeof(struct elf_file), M_LINKER, M_NOWAIT); 147 if (ef == NULL) 148 panic("link_elf_init: Can't create linker structures for kernel"); 149 bzero(ef, sizeof(*ef)); 150 151 ef->address = 0; 152#ifdef SPARSE_MAPPING 153 ef->object = 0; 154#endif 155 ef->dynamic = dp; 156 modname = NULL; 157 modptr = preload_search_by_type("elf kernel"); 158 if (modptr) 159 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 160 if (modname == NULL) 161 modname = "kernel"; 162 linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops); 163 if (linker_kernel_file == NULL) 164 panic("link_elf_init: Can't create linker structures for kernel"); 165 parse_dynamic(linker_kernel_file); 166 /* Sigh, magic constants. */ 167#ifdef __alpha__ 168 linker_kernel_file->address = (caddr_t) 0xfffffc0000300000; 169#else 170 linker_kernel_file->address = (caddr_t) 0xf0100000; 171#endif 172 linker_kernel_file->size = -(long)linker_kernel_file->address; 173 174 if (modptr) { 175 ef->modptr = modptr; 176 baseptr = preload_search_info(modptr, MODINFO_ADDR); 177 if (baseptr) 178 linker_kernel_file->address = *(caddr_t *)baseptr; 179 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 180 if (sizeptr) 181 linker_kernel_file->size = *(size_t *)sizeptr; 182 } 183 (void)parse_module_symbols(linker_kernel_file); 184 linker_current_file = linker_kernel_file; 185 } 186#endif 187} 188 189SYSINIT(link_elf, SI_SUB_KLD, SI_ORDER_SECOND, link_elf_init, 0); 190 191static int 192parse_module_symbols(linker_file_t lf) 193{ 194 elf_file_t ef = lf->priv; 195 caddr_t pointer; 196 caddr_t ssym, esym, base; 197 caddr_t strtab; 198 int strcnt; 199 Elf_Sym* symtab; 200 int symcnt; 201 202 if (ef->modptr == NULL) 203 return 0; 204 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 205 if (pointer == NULL) 206 return 0; 207 ssym = *(caddr_t *)pointer; 208 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 209 if (pointer == NULL) 210 return 0; 211 esym = *(caddr_t *)pointer; 212 213 base = ssym; 214 215 symcnt = *(long *)base; 216 base += sizeof(long); 217 symtab = (Elf_Sym *)base; 218 base += roundup(symcnt, sizeof(long)); 219 220 if (base > esym || base < ssym) { 221 printf("Symbols are corrupt!\n"); 222 return EINVAL; 223 } 224 225 strcnt = *(long *)base; 226 base += sizeof(long); 227 strtab = base; 228 base += roundup(strcnt, sizeof(long)); 229 230 if (base > esym || base < ssym) { 231 printf("Symbols are corrupt!\n"); 232 return EINVAL; 233 } 234 235 ef->ddbsymtab = symtab; 236 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 237 ef->ddbstrtab = strtab; 238 ef->ddbstrcnt = strcnt; 239 240 return 0; 241} 242 243static int 244parse_dynamic(linker_file_t lf) 245{ 246 elf_file_t ef = lf->priv; 247 const Elf_Dyn *dp; 248 int plttype = DT_REL; 249 250 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 251 switch (dp->d_tag) { 252 case DT_HASH: 253 { 254 /* From src/libexec/rtld-elf/rtld.c */ 255 const Elf_Off *hashtab = (const Elf_Off *) 256 (ef->address + dp->d_un.d_ptr); 257 ef->nbuckets = hashtab[0]; 258 ef->nchains = hashtab[1]; 259 ef->buckets = hashtab + 2; 260 ef->chains = ef->buckets + ef->nbuckets; 261 break; 262 } 263 case DT_STRTAB: 264 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 265 break; 266 case DT_STRSZ: 267 ef->strsz = dp->d_un.d_val; 268 break; 269 case DT_SYMTAB: 270 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 271 break; 272 case DT_SYMENT: 273 if (dp->d_un.d_val != sizeof(Elf_Sym)) 274 return ENOEXEC; 275 break; 276 case DT_PLTGOT: 277 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 278 break; 279 case DT_REL: 280 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 281 break; 282 case DT_RELSZ: 283 ef->relsize = dp->d_un.d_val; 284 break; 285 case DT_RELENT: 286 if (dp->d_un.d_val != sizeof(Elf_Rel)) 287 return ENOEXEC; 288 break; 289 case DT_JMPREL: 290 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 291 break; 292 case DT_PLTRELSZ: 293 ef->pltrelsize = dp->d_un.d_val; 294 break; 295 case DT_RELA: 296 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 297 break; 298 case DT_RELASZ: 299 ef->relasize = dp->d_un.d_val; 300 break; 301 case DT_RELAENT: 302 if (dp->d_un.d_val != sizeof(Elf_Rela)) 303 return ENOEXEC; 304 break; 305 case DT_PLTREL: 306 plttype = dp->d_un.d_val; 307 if (plttype != DT_REL && plttype != DT_RELA) 308 return ENOEXEC; 309 break; 310 } 311 } 312 313 if (plttype == DT_RELA) { 314 ef->pltrela = (const Elf_Rela *) ef->pltrel; 315 ef->pltrel = NULL; 316 ef->pltrelasize = ef->pltrelsize; 317 ef->pltrelsize = 0; 318 } 319 320 ef->ddbsymtab = ef->symtab; 321 ef->ddbsymcnt = ef->nchains; 322 ef->ddbstrtab = ef->strtab; 323 ef->ddbstrcnt = ef->strsz; 324 325 return 0; 326} 327 328static void 329link_elf_error(const char *s) 330{ 331 printf("kldload: %s\n", s); 332} 333 334static int 335link_elf_load_module(const char *filename, linker_file_t *result) 336{ 337 caddr_t modptr, baseptr, sizeptr, dynptr; 338 char *type; 339 elf_file_t ef; 340 linker_file_t lf; 341 int error; 342 vm_offset_t dp; 343 344 /* Look to see if we have the module preloaded */ 345 modptr = preload_search_by_name(filename); 346 if (modptr == NULL) 347 return (link_elf_load_file(filename, result)); 348 349 /* It's preloaded, check we can handle it and collect information */ 350 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 351 baseptr = preload_search_info(modptr, MODINFO_ADDR); 352 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 353 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 354 if (type == NULL || strcmp(type, "elf module") != 0) 355 return (EFTYPE); 356 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 357 return (EINVAL); 358 359 ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK); 360 if (ef == NULL) 361 return (ENOMEM); 362 bzero(ef, sizeof(*ef)); 363 ef->modptr = modptr; 364 ef->address = *(caddr_t *)baseptr; 365#ifdef SPARSE_MAPPING 366 ef->object = 0; 367#endif 368 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 369 ef->dynamic = (Elf_Dyn *)dp; 370 lf = linker_make_file(filename, ef, &link_elf_module_ops); 371 if (lf == NULL) { 372 free(ef, M_LINKER); 373 return ENOMEM; 374 } 375 lf->address = ef->address; 376 lf->size = *(size_t *)sizeptr; 377 378 error = parse_dynamic(lf); 379 if (error) { 380 linker_file_unload(lf); 381 return error; 382 } 383 error = load_dependancies(lf); 384 if (error) { 385 linker_file_unload(lf); 386 return error; 387 } 388 error = relocate_file(lf); 389 if (error) { 390 linker_file_unload(lf); 391 return error; 392 } 393 (void)parse_module_symbols(lf); 394 *result = lf; 395 return (0); 396} 397 398static int 399link_elf_load_file(const char* filename, linker_file_t* result) 400{ 401 struct nameidata nd; 402 struct proc* p = curproc; /* XXX */ 403 union { 404 Elf_Ehdr hdr; 405 char buf[PAGE_SIZE]; 406 } u; 407 int nbytes, i; 408 Elf_Phdr *phdr; 409 Elf_Phdr *phlimit; 410 Elf_Phdr *segs[2]; 411 int nsegs; 412 Elf_Phdr *phdyn; 413 Elf_Phdr *phphdr; 414 caddr_t mapbase; 415 size_t mapsize; 416 Elf_Off base_offset; 417 Elf_Addr base_vaddr; 418 Elf_Addr base_vlimit; 419 int error = 0; 420 int resid; 421 elf_file_t ef; 422 linker_file_t lf; 423 char *pathname; 424 Elf_Shdr *shdr; 425 int symtabindex; 426 int symstrindex; 427 int symcnt; 428 int strcnt; 429 430 shdr = NULL; 431 lf = NULL; 432 433 pathname = linker_search_path(filename); 434 if (pathname == NULL) 435 return ENOENT; 436 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, pathname, p); 437 error = vn_open(&nd, FREAD, 0); 438 free(pathname, M_LINKER); 439 if (error) 440 return error; 441 442 /* 443 * Read the elf header from the file. 444 */ 445 error = vn_rdwr(UIO_READ, nd.ni_vp, (void*) &u, sizeof u, 0, 446 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p); 447 nbytes = sizeof u - resid; 448 if (error) 449 goto out; 450 451 if (!IS_ELF(u.hdr)) { 452 error = ENOEXEC; 453 goto out; 454 } 455 456 if (u.hdr.e_ident[EI_CLASS] != ELF_TARG_CLASS 457 || u.hdr.e_ident[EI_DATA] != ELF_TARG_DATA) { 458 link_elf_error("Unsupported file layout"); 459 error = ENOEXEC; 460 goto out; 461 } 462 if (u.hdr.e_ident[EI_VERSION] != EV_CURRENT 463 || u.hdr.e_version != EV_CURRENT) { 464 link_elf_error("Unsupported file version"); 465 error = ENOEXEC; 466 goto out; 467 } 468 if (u.hdr.e_type != ET_EXEC && u.hdr.e_type != ET_DYN) { 469 link_elf_error("Unsupported file type"); 470 error = ENOEXEC; 471 goto out; 472 } 473 if (u.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 (!((u.hdr.e_phentsize == sizeof(Elf_Phdr)) 485 || (u.hdr.e_phoff + u.hdr.e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) 486 || (u.hdr.e_phoff + u.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 *) (u.buf + u.hdr.e_phoff); 496 phlimit = phdr + u.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 = u.hdr.e_shnum * u.hdr.e_shentsize; 629 if (nbytes == 0 || u.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, u.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 < u.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 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 VOP_UNLOCK(nd.ni_vp, 0, p); 688 vn_close(nd.ni_vp, FREAD, p->p_ucred, p); 689 690 return error; 691} 692 693static void 694link_elf_unload_file(linker_file_t file) 695{ 696 elf_file_t ef = file->priv; 697 698 if (ef) { 699#ifdef SPARSE_MAPPING 700 if (ef->object) { 701 vm_map_remove(kernel_map, (vm_offset_t) ef->address, 702 (vm_offset_t) ef->address 703 + (ef->object->size << PAGE_SHIFT)); 704 vm_object_deallocate(ef->object); 705 } 706#else 707 if (ef->address) 708 free(ef->address, M_LINKER); 709#endif 710 if (ef->symbase) 711 free(ef->symbase, M_LINKER); 712 if (ef->strbase) 713 free(ef->strbase, M_LINKER); 714 free(ef, M_LINKER); 715 } 716} 717 718static void 719link_elf_unload_module(linker_file_t file) 720{ 721 elf_file_t ef = file->priv; 722 723 if (ef) 724 free(ef, M_LINKER); 725 if (file->filename) 726 preload_delete_name(file->filename); 727} 728 729static int 730load_dependancies(linker_file_t lf) 731{ 732 elf_file_t ef = lf->priv; 733 linker_file_t lfdep; 734 char* name; 735 const Elf_Dyn *dp; 736 int error = 0; 737 738 /* 739 * All files are dependant on /kernel. 740 */ 741 linker_kernel_file->refs++; 742 linker_file_add_dependancy(lf, linker_kernel_file); 743 744 745 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 746 if (dp->d_tag == DT_NEEDED) { 747 name = ef->strtab + dp->d_un.d_val; 748 749 error = linker_load_file(name, &lfdep); 750 if (error) 751 goto out; 752 error = linker_file_add_dependancy(lf, lfdep); 753 if (error) 754 goto out; 755 } 756 } 757 758out: 759 return error; 760} 761 762static const char * 763symbol_name(elf_file_t ef, Elf_Word r_info) 764{ 765 const Elf_Sym *ref; 766 767 if (ELF_R_SYM(r_info)) { 768 ref = ef->symtab + ELF_R_SYM(r_info); 769 return ef->strtab + ref->st_name; 770 } else 771 return NULL; 772} 773 774static int 775relocate_file(linker_file_t lf) 776{ 777 elf_file_t ef = lf->priv; 778 const Elf_Rel *rellim; 779 const Elf_Rel *rel; 780 const Elf_Rela *relalim; 781 const Elf_Rela *rela; 782 const char *symname; 783 784 /* Perform relocations without addend if there are any: */ 785 rel = ef->rel; 786 if (rel) { 787 rellim = (const Elf_Rel *) ((caddr_t) ef->rel + ef->relsize); 788 while (rel < rellim) { 789 symname = symbol_name(ef, rel->r_info); 790 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) 791 return ENOENT; 792 rel++; 793 } 794 } 795 796 /* Perform relocations with addend if there are any: */ 797 rela = ef->rela; 798 if (rela) { 799 relalim = (const Elf_Rela *) ((caddr_t) ef->rela + ef->relasize); 800 while (rela < relalim) { 801 symname = symbol_name(ef, rela->r_info); 802 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) 803 return ENOENT; 804 rela++; 805 } 806 } 807 808 /* Perform PLT relocations without addend if there are any: */ 809 rel = ef->pltrel; 810 if (rel) { 811 rellim = (const Elf_Rel *) ((caddr_t) ef->pltrel + ef->pltrelsize); 812 while (rel < rellim) { 813 symname = symbol_name(ef, rel->r_info); 814 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) 815 return ENOENT; 816 rel++; 817 } 818 } 819 820 /* Perform relocations with addend if there are any: */ 821 rela = ef->pltrela; 822 if (rela) { 823 relalim = (const Elf_Rela *) ((caddr_t) ef->pltrela + ef->pltrelasize); 824 while (rela < relalim) { 825 symname = symbol_name(ef, rela->r_info); 826 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) 827 return ENOENT; 828 rela++; 829 } 830 } 831 832 return 0; 833} 834 835/* 836 * Hash function for symbol table lookup. Don't even think about changing 837 * this. It is specified by the System V ABI. 838 */ 839static unsigned long 840elf_hash(const char *name) 841{ 842 const unsigned char *p = (const unsigned char *) name; 843 unsigned long h = 0; 844 unsigned long g; 845 846 while (*p != '\0') { 847 h = (h << 4) + *p++; 848 if ((g = h & 0xf0000000) != 0) 849 h ^= g >> 24; 850 h &= ~g; 851 } 852 return h; 853} 854 855int 856link_elf_lookup_symbol(linker_file_t lf, const char* name, linker_sym_t* sym) 857{ 858 elf_file_t ef = lf->priv; 859 unsigned long symnum; 860 const Elf_Sym* symp; 861 const char *strp; 862 unsigned long hash; 863 int i; 864 865 /* First, search hashed global symbols */ 866 hash = elf_hash(name); 867 symnum = ef->buckets[hash % ef->nbuckets]; 868 869 while (symnum != STN_UNDEF) { 870 if (symnum >= ef->nchains) { 871 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 872 return ENOENT; 873 } 874 875 symp = ef->symtab + symnum; 876 if (symp->st_name == 0) { 877 printf("link_elf_lookup_symbol: corrupt symbol table\n"); 878 return ENOENT; 879 } 880 881 strp = ef->strtab + symp->st_name; 882 883 if (strcmp(name, strp) == 0) { 884 if (symp->st_shndx != SHN_UNDEF || 885 (symp->st_value != 0 && 886 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 887 *sym = (linker_sym_t) symp; 888 return 0; 889 } else 890 return ENOENT; 891 } 892 893 symnum = ef->chains[symnum]; 894 } 895 896 /* If we have not found it, look at the full table (if loaded) */ 897 if (ef->symtab == ef->ddbsymtab) 898 return ENOENT; 899 900 /* Exhaustive search */ 901 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 902 strp = ef->ddbstrtab + symp->st_name; 903 if (strcmp(name, strp) == 0) { 904 if (symp->st_shndx != SHN_UNDEF || 905 (symp->st_value != 0 && 906 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 907 *sym = (linker_sym_t) symp; 908 return 0; 909 } else 910 return ENOENT; 911 } 912 } 913 914 return ENOENT; 915} 916 917static int 918link_elf_symbol_values(linker_file_t lf, linker_sym_t sym, linker_symval_t* symval) 919{ 920 elf_file_t ef = lf->priv; 921 Elf_Sym* es = (Elf_Sym*) sym; 922 923 if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) { 924 symval->name = ef->strtab + es->st_name; 925 symval->value = (caddr_t) ef->address + es->st_value; 926 symval->size = es->st_size; 927 return 0; 928 } 929 if (ef->symtab == ef->ddbsymtab) 930 return ENOENT; 931 if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) { 932 symval->name = ef->ddbstrtab + es->st_name; 933 symval->value = (caddr_t) ef->address + es->st_value; 934 symval->size = es->st_size; 935 return 0; 936 } 937 return ENOENT; 938} 939 940static int 941link_elf_search_symbol(linker_file_t lf, caddr_t value, 942 linker_sym_t* sym, long* diffp) 943{ 944 elf_file_t ef = lf->priv; 945 u_long off = (u_long) value; 946 u_long diff = off; 947 const Elf_Sym* es; 948 const Elf_Sym* best = 0; 949 int i; 950 951 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 952 if (es->st_name == 0) 953 continue; 954 if (off >= es->st_value) { 955 if (off - es->st_value < diff) { 956 diff = off - es->st_value; 957 best = es; 958 if (diff == 0) 959 break; 960 } else if (off - es->st_value == diff) { 961 best = es; 962 } 963 } 964 } 965 if (best == 0) 966 *diffp = off; 967 else 968 *diffp = diff; 969 *sym = (linker_sym_t) best; 970 971 return 0; 972} 973