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: src/sys/kern/link_elf.c,v 1.24 1999/12/24 15:33:36 bde 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/nlookup.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 #include <vm/pmap.h> 45 #include <vm/vm_map.h> 46 47 #if defined(__x86_64__) && defined(_KERNEL_VIRTUAL) 48 #include <stdio.h> 49 #endif 50 51 static int link_elf_preload_file(const char *, linker_file_t *); 52 static int link_elf_preload_finish(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 static int link_elf_lookup_set(linker_file_t, const char *, 63 void ***, void ***, int *); 64 static int elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *); 65 static void link_elf_reloc_local(linker_file_t lf); 66 67 static struct linker_class_ops link_elf_class_ops = { 68 link_elf_load_file, 69 link_elf_preload_file, 70 }; 71 72 static struct linker_file_ops link_elf_file_ops = { 73 .lookup_symbol = link_elf_lookup_symbol, 74 .symbol_values = link_elf_symbol_values, 75 .search_symbol = link_elf_search_symbol, 76 .unload = link_elf_unload_file, 77 .lookup_set = link_elf_lookup_set 78 }; 79 80 static struct linker_file_ops link_elf_module_ops = { 81 .lookup_symbol = link_elf_lookup_symbol, 82 .symbol_values = link_elf_symbol_values, 83 .search_symbol = link_elf_search_symbol, 84 .preload_finish = link_elf_preload_finish, 85 .unload = link_elf_unload_module, 86 .lookup_set = link_elf_lookup_set, 87 }; 88 89 typedef struct elf_file { 90 caddr_t address; /* Relocation address */ 91 const Elf_Dyn* dynamic; /* Symbol table etc. */ 92 Elf_Hashelt nbuckets; /* DT_HASH info */ 93 Elf_Hashelt nchains; 94 const Elf_Hashelt* buckets; 95 const Elf_Hashelt* chains; 96 caddr_t hash; 97 caddr_t strtab; /* DT_STRTAB */ 98 int strsz; /* DT_STRSZ */ 99 const Elf_Sym* symtab; /* DT_SYMTAB */ 100 Elf_Addr* got; /* DT_PLTGOT */ 101 const Elf_Rel* pltrel; /* DT_JMPREL */ 102 int pltrelsize; /* DT_PLTRELSZ */ 103 const Elf_Rela* pltrela; /* DT_JMPREL */ 104 int pltrelasize; /* DT_PLTRELSZ */ 105 const Elf_Rel* rel; /* DT_REL */ 106 int relsize; /* DT_RELSZ */ 107 const Elf_Rela* rela; /* DT_RELA */ 108 int relasize; /* DT_RELASZ */ 109 caddr_t modptr; 110 const Elf_Sym* ddbsymtab; /* The symbol table we are using */ 111 long ddbsymcnt; /* Number of symbols */ 112 caddr_t ddbstrtab; /* String table */ 113 long ddbstrcnt; /* number of bytes in string table */ 114 caddr_t symbase; /* malloc'ed symbold base */ 115 caddr_t strbase; /* malloc'ed string base */ 116 } *elf_file_t; 117 118 static int parse_dynamic(linker_file_t lf); 119 static int relocate_file(linker_file_t lf); 120 static int parse_module_symbols(linker_file_t lf); 121 122 /* 123 * The kernel symbol table starts here. 124 */ 125 extern struct _dynamic _DYNAMIC; 126 127 static void 128 link_elf_init(void* arg) 129 { 130 Elf_Dyn *dp; 131 caddr_t modptr, baseptr, sizeptr; 132 elf_file_t ef; 133 char *modname; 134 135 #if ELF_TARG_CLASS == ELFCLASS32 136 linker_add_class("elf32", NULL, &link_elf_class_ops); 137 #else 138 linker_add_class("elf64", NULL, &link_elf_class_ops); 139 #endif 140 141 dp = (Elf_Dyn*) &_DYNAMIC; 142 if (dp) { 143 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_INTWAIT | M_ZERO); 144 ef->address = NULL; 145 ef->dynamic = dp; 146 modname = NULL; 147 modptr = preload_search_by_type("elf kernel"); 148 if (modptr) 149 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 150 if (modname == NULL) 151 modname = "kernel"; 152 linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops); 153 if (linker_kernel_file == NULL) 154 panic("link_elf_init: Can't create linker structures for kernel"); 155 parse_dynamic(linker_kernel_file); 156 #if defined(__x86_64__) && defined(_KERNEL_VIRTUAL) 157 fprintf(stderr, "WARNING: KERNBASE being used\n"); 158 #endif 159 linker_kernel_file->address = (caddr_t) KERNBASE; 160 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address; 161 162 if (modptr) { 163 ef->modptr = modptr; 164 baseptr = preload_search_info(modptr, MODINFO_ADDR); 165 if (baseptr) 166 linker_kernel_file->address = *(caddr_t *)baseptr; 167 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 168 if (sizeptr) 169 linker_kernel_file->size = *(size_t *)sizeptr; 170 } 171 parse_module_symbols(linker_kernel_file); 172 linker_current_file = linker_kernel_file; 173 linker_kernel_file->flags |= LINKER_FILE_LINKED; 174 } 175 } 176 177 SYSINIT(link_elf, SI_BOOT2_KLD, SI_ORDER_SECOND, link_elf_init, 0); 178 179 static int 180 parse_module_symbols(linker_file_t lf) 181 { 182 elf_file_t ef = lf->priv; 183 caddr_t pointer; 184 caddr_t ssym, esym, base; 185 caddr_t strtab; 186 int strcnt; 187 Elf_Sym* symtab; 188 int symcnt; 189 190 if (ef->modptr == NULL) 191 return 0; 192 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 193 if (pointer == NULL) 194 return 0; 195 ssym = *(caddr_t *)pointer; 196 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 197 if (pointer == NULL) 198 return 0; 199 esym = *(caddr_t *)pointer; 200 201 base = ssym; 202 203 symcnt = *(long *)base; 204 base += sizeof(long); 205 symtab = (Elf_Sym *)base; 206 base += roundup(symcnt, sizeof(long)); 207 208 if (base > esym || base < ssym) { 209 kprintf("Symbols are corrupt!\n"); 210 return EINVAL; 211 } 212 213 strcnt = *(long *)base; 214 base += sizeof(long); 215 strtab = base; 216 base += roundup(strcnt, sizeof(long)); 217 218 if (base > esym || base < ssym) { 219 kprintf("Symbols are corrupt!\n"); 220 return EINVAL; 221 } 222 223 ef->ddbsymtab = symtab; 224 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 225 ef->ddbstrtab = strtab; 226 ef->ddbstrcnt = strcnt; 227 228 return 0; 229 } 230 231 static int 232 parse_dynamic(linker_file_t lf) 233 { 234 elf_file_t ef = lf->priv; 235 const Elf_Dyn *dp; 236 int plttype = DT_REL; 237 238 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 239 switch (dp->d_tag) { 240 case DT_HASH: 241 { 242 /* From src/libexec/rtld-elf/rtld.c */ 243 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 244 (ef->address + dp->d_un.d_ptr); 245 ef->nbuckets = hashtab[0]; 246 ef->nchains = hashtab[1]; 247 ef->buckets = hashtab + 2; 248 ef->chains = ef->buckets + ef->nbuckets; 249 break; 250 } 251 case DT_STRTAB: 252 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 253 break; 254 case DT_STRSZ: 255 ef->strsz = dp->d_un.d_val; 256 break; 257 case DT_SYMTAB: 258 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 259 break; 260 case DT_SYMENT: 261 if (dp->d_un.d_val != sizeof(Elf_Sym)) 262 return ENOEXEC; 263 break; 264 case DT_PLTGOT: 265 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 266 break; 267 case DT_REL: 268 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 269 break; 270 case DT_RELSZ: 271 ef->relsize = dp->d_un.d_val; 272 break; 273 case DT_RELENT: 274 if (dp->d_un.d_val != sizeof(Elf_Rel)) 275 return ENOEXEC; 276 break; 277 case DT_JMPREL: 278 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 279 break; 280 case DT_PLTRELSZ: 281 ef->pltrelsize = dp->d_un.d_val; 282 break; 283 case DT_RELA: 284 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 285 break; 286 case DT_RELASZ: 287 ef->relasize = dp->d_un.d_val; 288 break; 289 case DT_RELAENT: 290 if (dp->d_un.d_val != sizeof(Elf_Rela)) 291 return ENOEXEC; 292 break; 293 case DT_PLTREL: 294 plttype = dp->d_un.d_val; 295 if (plttype != DT_REL && plttype != DT_RELA) 296 return ENOEXEC; 297 break; 298 } 299 } 300 301 if (plttype == DT_RELA) { 302 ef->pltrela = (const Elf_Rela *) ef->pltrel; 303 ef->pltrel = NULL; 304 ef->pltrelasize = ef->pltrelsize; 305 ef->pltrelsize = 0; 306 } 307 308 ef->ddbsymtab = ef->symtab; 309 ef->ddbsymcnt = ef->nchains; 310 ef->ddbstrtab = ef->strtab; 311 ef->ddbstrcnt = ef->strsz; 312 313 return 0; 314 } 315 316 static void 317 link_elf_error(const char *s) 318 { 319 kprintf("kldload: %s\n", s); 320 } 321 322 static int 323 link_elf_preload_file(const char *filename, linker_file_t *result) 324 { 325 caddr_t modptr, baseptr, sizeptr, dynptr; 326 char *type; 327 elf_file_t ef; 328 linker_file_t lf; 329 int error; 330 vm_offset_t dp; 331 332 /* 333 * Look to see if we have the module preloaded. 334 */ 335 modptr = preload_search_by_name(filename); 336 if (modptr == NULL) 337 return ENOENT; 338 339 /* It's preloaded, check we can handle it and collect information */ 340 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 341 baseptr = preload_search_info(modptr, MODINFO_ADDR); 342 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 343 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 344 if (type == NULL || 345 (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 && 346 strcmp(type, "elf module") != 0)) 347 return (EFTYPE); 348 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 349 return (EINVAL); 350 351 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 352 ef->modptr = modptr; 353 ef->address = *(caddr_t *)baseptr; 354 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 355 ef->dynamic = (Elf_Dyn *)dp; 356 lf = linker_make_file(filename, ef, &link_elf_module_ops); 357 if (lf == NULL) { 358 kfree(ef, M_LINKER); 359 return ENOMEM; 360 } 361 lf->address = ef->address; 362 lf->size = *(size_t *)sizeptr; 363 364 error = parse_dynamic(lf); 365 if (error) { 366 linker_file_unload(lf); 367 return error; 368 } 369 link_elf_reloc_local(lf); 370 *result = lf; 371 return (0); 372 } 373 374 static int 375 link_elf_preload_finish(linker_file_t lf) 376 { 377 int error; 378 379 error = relocate_file(lf); 380 if (error) 381 return error; 382 parse_module_symbols(lf); 383 384 return (0); 385 } 386 387 static int 388 link_elf_load_file(const char* filename, linker_file_t* result) 389 { 390 struct nlookupdata nd; 391 struct thread *td = curthread; /* XXX */ 392 struct proc *p = td->td_proc; 393 struct vnode *vp; 394 Elf_Ehdr *hdr; 395 caddr_t firstpage; 396 int nbytes, i; 397 Elf_Phdr *phdr; 398 Elf_Phdr *phlimit; 399 Elf_Phdr *segs[2]; 400 int nsegs; 401 Elf_Phdr *phdyn; 402 caddr_t mapbase; 403 size_t mapsize; 404 Elf_Addr base_vaddr; 405 Elf_Addr base_vlimit; 406 int error = 0; 407 int resid; 408 elf_file_t ef; 409 linker_file_t lf; 410 char *pathname; 411 Elf_Shdr *shdr; 412 int symtabindex; 413 int symstrindex; 414 int symcnt; 415 int strcnt; 416 417 /* XXX Hack for firmware loading where p == NULL */ 418 if (p == NULL) { 419 p = &proc0; 420 } 421 422 KKASSERT(p != NULL); 423 if (p->p_ucred == NULL) { 424 kprintf("link_elf_load_file: cannot load '%s' from filesystem" 425 " this early\n", filename); 426 return ENOENT; 427 } 428 shdr = NULL; 429 lf = NULL; 430 pathname = linker_search_path(filename); 431 if (pathname == NULL) 432 return ENOENT; 433 434 error = nlookup_init(&nd, pathname, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP); 435 if (error == 0) 436 error = vn_open(&nd, NULL, FREAD, 0); 437 kfree(pathname, M_LINKER); 438 if (error) { 439 nlookup_done(&nd); 440 return error; 441 } 442 vp = nd.nl_open_vp; 443 nd.nl_open_vp = NULL; 444 nlookup_done(&nd); 445 446 /* 447 * Read the elf header from the file. 448 */ 449 firstpage = kmalloc(PAGE_SIZE, M_LINKER, M_WAITOK); 450 hdr = (Elf_Ehdr *)firstpage; 451 error = vn_rdwr(UIO_READ, vp, firstpage, PAGE_SIZE, 0, 452 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 453 nbytes = PAGE_SIZE - resid; 454 if (error) 455 goto out; 456 457 if (!IS_ELF(*hdr)) { 458 error = ENOEXEC; 459 goto out; 460 } 461 462 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 463 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 464 link_elf_error("Unsupported file layout"); 465 error = ENOEXEC; 466 goto out; 467 } 468 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 469 || hdr->e_version != EV_CURRENT) { 470 link_elf_error("Unsupported file version"); 471 error = ENOEXEC; 472 goto out; 473 } 474 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 475 error = ENOSYS; 476 goto out; 477 } 478 if (hdr->e_machine != ELF_TARG_MACH) { 479 link_elf_error("Unsupported machine"); 480 error = ENOEXEC; 481 goto out; 482 } 483 484 /* 485 * We rely on the program header being in the first page. This is 486 * not strictly required by the ABI specification, but it seems to 487 * always true in practice. And, it simplifies things considerably. 488 */ 489 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 490 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 491 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 492 link_elf_error("Unreadable program headers"); 493 494 /* 495 * Scan the program header entries, and save key information. 496 * 497 * We rely on there being exactly two load segments, text and data, 498 * in that order. 499 */ 500 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 501 phlimit = phdr + hdr->e_phnum; 502 nsegs = 0; 503 phdyn = NULL; 504 while (phdr < phlimit) { 505 switch (phdr->p_type) { 506 507 case PT_LOAD: 508 if (nsegs == 2) { 509 link_elf_error("Too many sections"); 510 error = ENOEXEC; 511 goto out; 512 } 513 segs[nsegs] = phdr; 514 ++nsegs; 515 break; 516 517 case PT_PHDR: 518 break; 519 520 case PT_DYNAMIC: 521 phdyn = phdr; 522 break; 523 524 case PT_INTERP: 525 error = ENOSYS; 526 goto out; 527 } 528 529 ++phdr; 530 } 531 if (phdyn == NULL) { 532 link_elf_error("Object is not dynamically-linked"); 533 error = ENOEXEC; 534 goto out; 535 } 536 537 /* 538 * Allocate the entire address space of the object, to stake out our 539 * contiguous region, and to establish the base address for relocation. 540 */ 541 base_vaddr = trunc_page(segs[0]->p_vaddr); 542 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); 543 mapsize = base_vlimit - base_vaddr; 544 545 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 546 ef->address = kmalloc(mapsize, M_LINKER, M_WAITOK); 547 mapbase = ef->address; 548 549 /* 550 * Read the text and data sections and zero the bss. 551 */ 552 for (i = 0; i < 2; i++) { 553 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 554 error = vn_rdwr(UIO_READ, vp, 555 segbase, segs[i]->p_filesz, segs[i]->p_offset, 556 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 557 if (error) { 558 kfree(ef->address, M_LINKER); 559 kfree(ef, M_LINKER); 560 goto out; 561 } 562 bzero(segbase + segs[i]->p_filesz, 563 segs[i]->p_memsz - segs[i]->p_filesz); 564 } 565 566 ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 567 568 lf = linker_make_file(filename, ef, &link_elf_file_ops); 569 if (lf == NULL) { 570 kfree(ef->address, M_LINKER); 571 kfree(ef, M_LINKER); 572 error = ENOMEM; 573 goto out; 574 } 575 lf->address = ef->address; 576 lf->size = mapsize; 577 578 error = parse_dynamic(lf); 579 if (error) 580 goto out; 581 link_elf_reloc_local(lf); 582 error = linker_load_dependencies(lf); 583 if (error) 584 goto out; 585 error = relocate_file(lf); 586 if (error) 587 goto out; 588 589 /* Try and load the symbol table if it's present. (you can strip it!) */ 590 nbytes = hdr->e_shnum * hdr->e_shentsize; 591 if (nbytes == 0 || hdr->e_shoff == 0) 592 goto nosyms; 593 shdr = kmalloc(nbytes, M_LINKER, M_WAITOK | M_ZERO); 594 error = vn_rdwr(UIO_READ, vp, 595 (caddr_t)shdr, nbytes, hdr->e_shoff, 596 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 597 if (error) 598 goto out; 599 symtabindex = -1; 600 symstrindex = -1; 601 for (i = 0; i < hdr->e_shnum; i++) { 602 if (shdr[i].sh_type == SHT_SYMTAB) { 603 symtabindex = i; 604 symstrindex = shdr[i].sh_link; 605 } 606 } 607 if (symtabindex < 0 || symstrindex < 0) 608 goto nosyms; 609 610 symcnt = shdr[symtabindex].sh_size; 611 ef->symbase = kmalloc(symcnt, M_LINKER, M_WAITOK); 612 strcnt = shdr[symstrindex].sh_size; 613 ef->strbase = kmalloc(strcnt, M_LINKER, M_WAITOK); 614 error = vn_rdwr(UIO_READ, vp, 615 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 616 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 617 if (error) 618 goto out; 619 error = vn_rdwr(UIO_READ, vp, 620 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 621 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 622 if (error) 623 goto out; 624 625 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 626 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 627 ef->ddbstrcnt = strcnt; 628 ef->ddbstrtab = ef->strbase; 629 630 nosyms: 631 632 *result = lf; 633 634 out: 635 if (error && lf) 636 linker_file_unload(lf); 637 if (shdr) 638 kfree(shdr, M_LINKER); 639 if (firstpage) 640 kfree(firstpage, M_LINKER); 641 vn_unlock(vp); 642 vn_close(vp, FREAD, NULL); 643 644 return error; 645 } 646 647 Elf_Addr 648 elf_relocaddr(linker_file_t lf, Elf_Addr x) 649 { 650 #if 0 651 elf_file_t ef; 652 653 ef = lf->priv; 654 if (x >= ef->pcpu_start && x < ef->pcpu_stop) 655 return ((x - ef->pcpu_start) + ef->pcpu_base); 656 #ifdef VIMAGE 657 if (x >= ef->vnet_start && x < ef->vnet_stop) 658 return ((x - ef->vnet_start) + ef->vnet_base); 659 #endif 660 #endif 661 return (x); 662 } 663 664 static void 665 link_elf_unload_file(linker_file_t file) 666 { 667 elf_file_t ef = file->priv; 668 669 if (ef) { 670 if (ef->address) 671 kfree(ef->address, M_LINKER); 672 if (ef->symbase) 673 kfree(ef->symbase, M_LINKER); 674 if (ef->strbase) 675 kfree(ef->strbase, M_LINKER); 676 kfree(ef, M_LINKER); 677 } 678 } 679 680 static void 681 link_elf_unload_module(linker_file_t file) 682 { 683 elf_file_t ef = file->priv; 684 685 if (ef) 686 kfree(ef, M_LINKER); 687 if (file->pathname) 688 preload_delete_name(file->pathname); 689 } 690 691 static const char * 692 symbol_name(elf_file_t ef, Elf_Size r_info) 693 { 694 const Elf_Sym *ref; 695 696 if (ELF_R_SYM(r_info)) { 697 ref = ef->symtab + ELF_R_SYM(r_info); 698 return ef->strtab + ref->st_name; 699 } else 700 return NULL; 701 } 702 703 static int 704 relocate_file(linker_file_t lf) 705 { 706 elf_file_t ef = lf->priv; 707 const Elf_Rel *rellim; 708 const Elf_Rel *rel; 709 const Elf_Rela *relalim; 710 const Elf_Rela *rela; 711 const char *symname; 712 713 /* Perform relocations without addend if there are any: */ 714 rel = ef->rel; 715 if (rel) { 716 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 717 while (rel < rellim) { 718 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) { 719 symname = symbol_name(ef, rel->r_info); 720 kprintf("link_elf: symbol %s undefined\n", symname); 721 return ENOENT; 722 } 723 rel++; 724 } 725 } 726 727 /* Perform relocations with addend if there are any: */ 728 rela = ef->rela; 729 if (rela) { 730 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 731 while (rela < relalim) { 732 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) { 733 symname = symbol_name(ef, rela->r_info); 734 kprintf("link_elf: symbol %s undefined\n", symname); 735 return ENOENT; 736 } 737 rela++; 738 } 739 } 740 741 /* Perform PLT relocations without addend if there are any: */ 742 rel = ef->pltrel; 743 if (rel) { 744 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 745 while (rel < rellim) { 746 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) { 747 symname = symbol_name(ef, rel->r_info); 748 kprintf("link_elf: symbol %s undefined\n", symname); 749 return ENOENT; 750 } 751 rel++; 752 } 753 } 754 755 /* Perform relocations with addend if there are any: */ 756 rela = ef->pltrela; 757 if (rela) { 758 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 759 while (rela < relalim) { 760 symname = symbol_name(ef, rela->r_info); 761 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) { 762 kprintf("link_elf: symbol %s undefined\n", symname); 763 return ENOENT; 764 } 765 rela++; 766 } 767 } 768 769 return 0; 770 } 771 772 /* 773 * Hash function for symbol table lookup. Don't even think about changing 774 * this. It is specified by the System V ABI. 775 */ 776 static unsigned long 777 elf_hash(const char *name) 778 { 779 const unsigned char *p = (const unsigned char *) name; 780 unsigned long h = 0; 781 unsigned long g; 782 783 while (*p != '\0') { 784 h = (h << 4) + *p++; 785 if ((g = h & 0xf0000000) != 0) 786 h ^= g >> 24; 787 h &= ~g; 788 } 789 return h; 790 } 791 792 static int 793 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 794 { 795 elf_file_t ef = lf->priv; 796 unsigned long symnum; 797 const Elf_Sym* symp; 798 const char *strp; 799 unsigned long hash; 800 int i; 801 802 /* If we don't have a hash, bail. */ 803 if (ef->buckets == NULL || ef->nbuckets == 0) { 804 kprintf("link_elf_lookup_symbol: missing symbol hash table\n"); 805 return ENOENT; 806 } 807 808 /* First, search hashed global symbols */ 809 hash = elf_hash(name); 810 symnum = ef->buckets[hash % ef->nbuckets]; 811 812 while (symnum != STN_UNDEF) { 813 if (symnum >= ef->nchains) { 814 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 815 return ENOENT; 816 } 817 818 symp = ef->symtab + symnum; 819 if (symp->st_name == 0) { 820 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 821 return ENOENT; 822 } 823 824 strp = ef->strtab + symp->st_name; 825 826 if (strcmp(name, strp) == 0) { 827 if (symp->st_shndx != SHN_UNDEF || 828 (symp->st_value != 0 && 829 ELF_ST_TYPE(symp->st_info) == STT_FUNC) 830 ) { 831 *sym = (c_linker_sym_t) symp; 832 return 0; 833 } else { 834 return ENOENT; 835 } 836 } 837 838 symnum = ef->chains[symnum]; 839 } 840 841 /* If we have not found it, look at the full table (if loaded) */ 842 if (ef->symtab == ef->ddbsymtab) 843 return ENOENT; 844 845 /* Exhaustive search */ 846 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 847 strp = ef->ddbstrtab + symp->st_name; 848 if (strcmp(name, strp) == 0) { 849 if (symp->st_shndx != SHN_UNDEF || 850 (symp->st_value != 0 && 851 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 852 *sym = (c_linker_sym_t) symp; 853 return 0; 854 } else { 855 return ENOENT; 856 } 857 } 858 } 859 return ENOENT; 860 } 861 862 static int 863 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t *symval) 864 { 865 elf_file_t ef = lf->priv; 866 const Elf_Sym *es = (const Elf_Sym *)sym; 867 868 symval->value = 0; /* avoid gcc warnings */ 869 870 if (es >= ef->symtab && es < (ef->symtab + ef->nchains)) { 871 symval->name = ef->strtab + es->st_name; 872 symval->value = ef->address + es->st_value; 873 symval->size = es->st_size; 874 return 0; 875 } 876 if (ef->symtab == ef->ddbsymtab) 877 return ENOENT; 878 if (es >= ef->ddbsymtab && es < (ef->ddbsymtab + ef->ddbsymcnt)) { 879 symval->name = ef->ddbstrtab + es->st_name; 880 symval->value = ef->address + es->st_value; 881 symval->size = es->st_size; 882 return 0; 883 } 884 return ENOENT; 885 } 886 887 static int 888 link_elf_search_symbol(linker_file_t lf, caddr_t value, 889 c_linker_sym_t *sym, long *diffp) 890 { 891 elf_file_t ef = lf->priv; 892 u_long off = (uintptr_t)(void *)value; 893 u_long diff = off; 894 u_long st_value; 895 const Elf_Sym *es; 896 const Elf_Sym *best = NULL; 897 int i; 898 899 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 900 if (es->st_name == 0) 901 continue; 902 st_value = es->st_value + (uintptr_t)(void *)ef->address; 903 if (off >= st_value) { 904 if (off - st_value < diff) { 905 diff = off - st_value; 906 best = es; 907 if (diff == 0) 908 break; 909 } else if (off - st_value == diff) { 910 best = es; 911 } 912 } 913 } 914 if (best == NULL) 915 *diffp = off; 916 else 917 *diffp = diff; 918 *sym = (c_linker_sym_t) best; 919 920 return 0; 921 } 922 923 /* 924 * Look up a linker set on an ELF system. 925 */ 926 static int 927 link_elf_lookup_set(linker_file_t lf, const char *name, 928 void ***startp, void ***stopp, int *countp) 929 { 930 c_linker_sym_t sym; 931 linker_symval_t symval; 932 char *setsym; 933 void **start, **stop; 934 int len, error = 0, count; 935 936 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */ 937 setsym = kmalloc(len, M_LINKER, M_WAITOK); 938 939 /* get address of first entry */ 940 ksnprintf(setsym, len, "%s%s", "__start_set_", name); 941 error = link_elf_lookup_symbol(lf, setsym, &sym); 942 if (error) 943 goto out; 944 link_elf_symbol_values(lf, sym, &symval); 945 if (symval.value == NULL) { 946 error = ESRCH; 947 goto out; 948 } 949 start = (void **)symval.value; 950 951 /* get address of last entry */ 952 ksnprintf(setsym, len, "%s%s", "__stop_set_", name); 953 error = link_elf_lookup_symbol(lf, setsym, &sym); 954 if (error) 955 goto out; 956 link_elf_symbol_values(lf, sym, &symval); 957 if (symval.value == NULL) { 958 error = ESRCH; 959 goto out; 960 } 961 stop = (void **)symval.value; 962 963 /* and the number of entries */ 964 count = stop - start; 965 966 /* and copy out */ 967 if (startp) 968 *startp = start; 969 if (stopp) 970 *stopp = stop; 971 if (countp) 972 *countp = count; 973 974 out: 975 kfree(setsym, M_LINKER); 976 return error; 977 } 978 979 /* 980 * Symbol lookup function that can be used when the symbol index is known (ie 981 * in relocations). It uses the symbol index instead of doing a fully fledged 982 * hash table based lookup when such is valid. For example for local symbols. 983 * This is not only more efficient, it's also more correct. It's not always 984 * the case that the symbol can be found through the hash table. 985 */ 986 static int 987 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *result) 988 { 989 elf_file_t ef = lf->priv; 990 const Elf_Sym *sym; 991 const char *symbol; 992 993 /* Don't even try to lookup the symbol if the index is bogus. */ 994 if (symidx >= ef->nchains) 995 return (ENOENT); 996 997 sym = ef->symtab + symidx; 998 999 /* 1000 * Don't do a full lookup when the symbol is local. It may even 1001 * fail because it may not be found through the hash table. 1002 */ 1003 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) { 1004 /* Force lookup failure when we have an insanity. */ 1005 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0) 1006 return (ENOENT); 1007 return ((Elf_Addr) ef->address + sym->st_value); 1008 } 1009 /* 1010 * XXX we can avoid doing a hash table based lookup for global 1011 * symbols as well. This however is not always valid, so we'll 1012 * just do it the hard way for now. Performance tweaks can 1013 * always be added. 1014 */ 1015 1016 symbol = ef->strtab + sym->st_name; 1017 1018 /* Force a lookup failure if the symbol name is bogus. */ 1019 if (*symbol == 0) 1020 return (ENOENT); 1021 1022 return (linker_file_lookup_symbol(lf, symbol, deps, (caddr_t *)result)); 1023 } 1024 static void 1025 link_elf_reloc_local(linker_file_t lf) 1026 { 1027 elf_file_t ef = lf->priv; 1028 const Elf_Rel *rellim; 1029 const Elf_Rel *rel; 1030 const Elf_Rela *relalim; 1031 const Elf_Rela *rela; 1032 1033 /* Perform relocations without addend if there are any: */ 1034 if ((rel = ef->rel) != NULL) { 1035 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 1036 while (rel < rellim) { 1037 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, 1038 elf_lookup); 1039 rel++; 1040 } 1041 } 1042 1043 /* Perform relocations with addend if there are any: */ 1044 if ((rela = ef->rela) != NULL) { 1045 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 1046 while (rela < relalim) { 1047 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, 1048 elf_lookup); 1049 rela++; 1050 } 1051 } 1052 } 1053