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 * $DragonFly: src/sys/kern/link_elf.c,v 1.29 2008/08/01 23:11:16 dillon Exp $ 28 */ 29 30 #include <sys/param.h> 31 #include <sys/kernel.h> 32 #include <sys/systm.h> 33 #include <sys/malloc.h> 34 #include <sys/proc.h> 35 #include <sys/nlookup.h> 36 #include <sys/fcntl.h> 37 #include <sys/vnode.h> 38 #include <sys/linker.h> 39 #include <machine/elf.h> 40 41 #include <vm/vm.h> 42 #include <vm/vm_param.h> 43 #include <vm/vm_zone.h> 44 #include <sys/lock.h> 45 #ifdef SPARSE_MAPPING 46 #include <vm/vm_object.h> 47 #include <vm/vm_kern.h> 48 #include <vm/vm_extern.h> 49 #endif 50 #include <vm/pmap.h> 51 #include <vm/vm_map.h> 52 53 #if defined(__amd64__) && defined(_KERNEL_VIRTUAL) 54 #include <stdio.h> 55 #endif 56 57 static int link_elf_preload_file(const char *, linker_file_t *); 58 static int link_elf_preload_finish(linker_file_t); 59 static int link_elf_load_file(const char*, linker_file_t*); 60 static int link_elf_lookup_symbol(linker_file_t, const char*, 61 c_linker_sym_t*); 62 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*); 63 static int link_elf_search_symbol(linker_file_t, caddr_t value, 64 c_linker_sym_t* sym, long* diffp); 65 66 static void link_elf_unload_file(linker_file_t); 67 static void link_elf_unload_module(linker_file_t); 68 static int link_elf_lookup_set(linker_file_t, const char *, 69 void ***, void ***, int *); 70 static int elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *); 71 static void link_elf_reloc_local(linker_file_t lf); 72 73 static struct linker_class_ops link_elf_class_ops = { 74 link_elf_load_file, 75 link_elf_preload_file, 76 }; 77 78 static struct linker_file_ops link_elf_file_ops = { 79 .lookup_symbol = link_elf_lookup_symbol, 80 .symbol_values = link_elf_symbol_values, 81 .search_symbol = link_elf_search_symbol, 82 .unload = link_elf_unload_file, 83 .lookup_set = link_elf_lookup_set 84 }; 85 86 static struct linker_file_ops link_elf_module_ops = { 87 .lookup_symbol = link_elf_lookup_symbol, 88 .symbol_values = link_elf_symbol_values, 89 .search_symbol = link_elf_search_symbol, 90 .preload_finish = link_elf_preload_finish, 91 .unload = link_elf_unload_module, 92 .lookup_set = link_elf_lookup_set, 93 }; 94 95 typedef struct elf_file { 96 caddr_t address; /* Relocation address */ 97 #ifdef SPARSE_MAPPING 98 vm_object_t object; /* VM object to hold file pages */ 99 #endif 100 const Elf_Dyn* dynamic; /* Symbol table etc. */ 101 Elf_Hashelt nbuckets; /* DT_HASH info */ 102 Elf_Hashelt nchains; 103 const Elf_Hashelt* buckets; 104 const Elf_Hashelt* chains; 105 caddr_t hash; 106 caddr_t strtab; /* DT_STRTAB */ 107 int strsz; /* DT_STRSZ */ 108 const Elf_Sym* symtab; /* DT_SYMTAB */ 109 Elf_Addr* got; /* DT_PLTGOT */ 110 const Elf_Rel* pltrel; /* DT_JMPREL */ 111 int pltrelsize; /* DT_PLTRELSZ */ 112 const Elf_Rela* pltrela; /* DT_JMPREL */ 113 int pltrelasize; /* DT_PLTRELSZ */ 114 const Elf_Rel* rel; /* DT_REL */ 115 int relsize; /* DT_RELSZ */ 116 const Elf_Rela* rela; /* DT_RELA */ 117 int relasize; /* DT_RELASZ */ 118 caddr_t modptr; 119 const Elf_Sym* ddbsymtab; /* The symbol table we are using */ 120 long ddbsymcnt; /* Number of symbols */ 121 caddr_t ddbstrtab; /* String table */ 122 long ddbstrcnt; /* number of bytes in string table */ 123 caddr_t symbase; /* malloc'ed symbold base */ 124 caddr_t strbase; /* malloc'ed string base */ 125 } *elf_file_t; 126 127 static int parse_dynamic(linker_file_t lf); 128 static int relocate_file(linker_file_t lf); 129 static int parse_module_symbols(linker_file_t lf); 130 131 /* 132 * The kernel symbol table starts here. 133 */ 134 extern struct _dynamic _DYNAMIC; 135 136 static void 137 link_elf_init(void* arg) 138 { 139 Elf_Dyn *dp; 140 caddr_t modptr, baseptr, sizeptr; 141 elf_file_t ef; 142 char *modname; 143 144 #if ELF_TARG_CLASS == ELFCLASS32 145 linker_add_class("elf32", NULL, &link_elf_class_ops); 146 #else 147 linker_add_class("elf64", NULL, &link_elf_class_ops); 148 #endif 149 150 dp = (Elf_Dyn*) &_DYNAMIC; 151 if (dp) { 152 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_INTWAIT | M_ZERO); 153 ef->address = 0; 154 #ifdef SPARSE_MAPPING 155 ef->object = 0; 156 #endif 157 ef->dynamic = dp; 158 modname = NULL; 159 modptr = preload_search_by_type("elf kernel"); 160 if (modptr) 161 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 162 if (modname == NULL) 163 modname = "kernel"; 164 linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops); 165 if (linker_kernel_file == NULL) 166 panic("link_elf_init: Can't create linker structures for kernel"); 167 parse_dynamic(linker_kernel_file); 168 #if defined(__amd64__) && defined(_KERNEL_VIRTUAL) 169 fprintf(stderr, "WARNING: KERNBASE being used\n"); 170 #endif 171 linker_kernel_file->address = (caddr_t) KERNBASE; 172 linker_kernel_file->size = -(intptr_t)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 parse_module_symbols(linker_kernel_file); 184 linker_current_file = linker_kernel_file; 185 linker_kernel_file->flags |= LINKER_FILE_LINKED; 186 } 187 } 188 189 SYSINIT(link_elf, SI_BOOT2_KLD, SI_ORDER_SECOND, link_elf_init, 0); 190 191 static int 192 parse_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 kprintf("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 kprintf("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 } 242 243 static int 244 parse_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_Hashelt *hashtab = (const Elf_Hashelt *) 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 } 327 328 static void 329 link_elf_error(const char *s) 330 { 331 kprintf("kldload: %s\n", s); 332 } 333 334 static int 335 link_elf_preload_file(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 /* 345 * Look to see if we have the module preloaded. 346 */ 347 modptr = preload_search_by_name(filename); 348 if (modptr == NULL) 349 return ENOENT; 350 351 /* It's preloaded, check we can handle it and collect information */ 352 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 353 baseptr = preload_search_info(modptr, MODINFO_ADDR); 354 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 355 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 356 if (type == NULL || 357 (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 && 358 strcmp(type, "elf module") != 0)) 359 return (EFTYPE); 360 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 361 return (EINVAL); 362 363 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 364 ef->modptr = modptr; 365 ef->address = *(caddr_t *)baseptr; 366 #ifdef SPARSE_MAPPING 367 ef->object = 0; 368 #endif 369 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 370 ef->dynamic = (Elf_Dyn *)dp; 371 lf = linker_make_file(filename, ef, &link_elf_module_ops); 372 if (lf == NULL) { 373 kfree(ef, M_LINKER); 374 return ENOMEM; 375 } 376 lf->address = ef->address; 377 lf->size = *(size_t *)sizeptr; 378 379 error = parse_dynamic(lf); 380 if (error) { 381 linker_file_unload(lf); 382 return error; 383 } 384 link_elf_reloc_local(lf); 385 *result = lf; 386 return (0); 387 } 388 389 static int 390 link_elf_preload_finish(linker_file_t lf) 391 { 392 int error; 393 394 error = relocate_file(lf); 395 if (error) 396 return error; 397 parse_module_symbols(lf); 398 399 return (0); 400 } 401 402 static int 403 link_elf_load_file(const char* filename, linker_file_t* result) 404 { 405 struct nlookupdata nd; 406 struct thread *td = curthread; /* XXX */ 407 struct proc *p = td->td_proc; 408 struct vnode *vp; 409 Elf_Ehdr *hdr; 410 caddr_t firstpage; 411 int nbytes, i; 412 Elf_Phdr *phdr; 413 Elf_Phdr *phlimit; 414 Elf_Phdr *segs[2]; 415 int nsegs; 416 Elf_Phdr *phdyn; 417 Elf_Phdr *phphdr; 418 caddr_t mapbase; 419 size_t mapsize; 420 Elf_Off base_offset; 421 Elf_Addr base_vaddr; 422 Elf_Addr base_vlimit; 423 int error = 0; 424 int resid; 425 elf_file_t ef; 426 linker_file_t lf; 427 char *pathname; 428 Elf_Shdr *shdr; 429 int symtabindex; 430 int symstrindex; 431 int symcnt; 432 int strcnt; 433 434 /* XXX Hack for firmware loading where p == NULL */ 435 if (p == NULL) { 436 p = &proc0; 437 } 438 439 KKASSERT(p != NULL); 440 if (p->p_ucred == NULL) { 441 kprintf("link_elf_load_file: cannot load '%s' from filesystem" 442 " this early\n", filename); 443 return ENOENT; 444 } 445 shdr = NULL; 446 lf = NULL; 447 pathname = linker_search_path(filename); 448 if (pathname == NULL) 449 return ENOENT; 450 451 error = nlookup_init(&nd, pathname, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP); 452 if (error == 0) 453 error = vn_open(&nd, NULL, FREAD, 0); 454 kfree(pathname, M_LINKER); 455 if (error) { 456 nlookup_done(&nd); 457 return error; 458 } 459 vp = nd.nl_open_vp; 460 nd.nl_open_vp = NULL; 461 nlookup_done(&nd); 462 463 /* 464 * Read the elf header from the file. 465 */ 466 firstpage = kmalloc(PAGE_SIZE, M_LINKER, M_WAITOK); 467 hdr = (Elf_Ehdr *)firstpage; 468 error = vn_rdwr(UIO_READ, vp, firstpage, PAGE_SIZE, 0, 469 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 470 nbytes = PAGE_SIZE - resid; 471 if (error) 472 goto out; 473 474 if (!IS_ELF(*hdr)) { 475 error = ENOEXEC; 476 goto out; 477 } 478 479 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 480 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 481 link_elf_error("Unsupported file layout"); 482 error = ENOEXEC; 483 goto out; 484 } 485 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 486 || hdr->e_version != EV_CURRENT) { 487 link_elf_error("Unsupported file version"); 488 error = ENOEXEC; 489 goto out; 490 } 491 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 492 error = ENOSYS; 493 goto out; 494 } 495 if (hdr->e_machine != ELF_TARG_MACH) { 496 link_elf_error("Unsupported machine"); 497 error = ENOEXEC; 498 goto out; 499 } 500 501 /* 502 * We rely on the program header being in the first page. This is 503 * not strictly required by the ABI specification, but it seems to 504 * always true in practice. And, it simplifies things considerably. 505 */ 506 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 507 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 508 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 509 link_elf_error("Unreadable program headers"); 510 511 /* 512 * Scan the program header entries, and save key information. 513 * 514 * We rely on there being exactly two load segments, text and data, 515 * in that order. 516 */ 517 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 518 phlimit = phdr + hdr->e_phnum; 519 nsegs = 0; 520 phdyn = NULL; 521 phphdr = NULL; 522 while (phdr < phlimit) { 523 switch (phdr->p_type) { 524 525 case PT_LOAD: 526 if (nsegs == 2) { 527 link_elf_error("Too many sections"); 528 error = ENOEXEC; 529 goto out; 530 } 531 segs[nsegs] = phdr; 532 ++nsegs; 533 break; 534 535 case PT_PHDR: 536 phphdr = phdr; 537 break; 538 539 case PT_DYNAMIC: 540 phdyn = phdr; 541 break; 542 543 case PT_INTERP: 544 error = ENOSYS; 545 goto out; 546 } 547 548 ++phdr; 549 } 550 if (phdyn == NULL) { 551 link_elf_error("Object is not dynamically-linked"); 552 error = ENOEXEC; 553 goto out; 554 } 555 556 /* 557 * Allocate the entire address space of the object, to stake out our 558 * contiguous region, and to establish the base address for relocation. 559 */ 560 base_offset = trunc_page(segs[0]->p_offset); 561 base_vaddr = trunc_page(segs[0]->p_vaddr); 562 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); 563 mapsize = base_vlimit - base_vaddr; 564 565 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 566 #ifdef SPARSE_MAPPING 567 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 568 if (ef->object == NULL) { 569 kfree(ef, M_LINKER); 570 error = ENOMEM; 571 goto out; 572 } 573 vm_object_reference(ef->object); 574 ef->address = (caddr_t)vm_map_min(&kernel_map); 575 error = vm_map_find(&kernel_map, ef->object, 0, 576 (vm_offset_t *)&ef->address, 577 mapsize, PAGE_SIZE, 578 1, VM_MAPTYPE_NORMAL, 579 VM_PROT_ALL, VM_PROT_ALL, 580 0); 581 if (error) { 582 vm_object_deallocate(ef->object); 583 kfree(ef, M_LINKER); 584 goto out; 585 } 586 #else 587 ef->address = kmalloc(mapsize, M_LINKER, M_WAITOK); 588 #endif 589 mapbase = ef->address; 590 591 /* 592 * Read the text and data sections and zero the bss. 593 */ 594 for (i = 0; i < 2; i++) { 595 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 596 error = vn_rdwr(UIO_READ, vp, 597 segbase, segs[i]->p_filesz, segs[i]->p_offset, 598 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 599 if (error) { 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 kfree(ef->address, M_LINKER); 607 #endif 608 kfree(ef, M_LINKER); 609 goto out; 610 } 611 bzero(segbase + segs[i]->p_filesz, 612 segs[i]->p_memsz - segs[i]->p_filesz); 613 614 #ifdef SPARSE_MAPPING 615 /* 616 * Wire down the pages 617 */ 618 vm_map_wire(&kernel_map, 619 (vm_offset_t) segbase, 620 (vm_offset_t) segbase + segs[i]->p_memsz, 621 0); 622 #endif 623 } 624 625 ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 626 627 lf = linker_make_file(filename, ef, &link_elf_file_ops); 628 if (lf == NULL) { 629 #ifdef SPARSE_MAPPING 630 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 631 (vm_offset_t) ef->address 632 + (ef->object->size << PAGE_SHIFT)); 633 vm_object_deallocate(ef->object); 634 #else 635 kfree(ef->address, M_LINKER); 636 #endif 637 kfree(ef, M_LINKER); 638 error = ENOMEM; 639 goto out; 640 } 641 lf->address = ef->address; 642 lf->size = mapsize; 643 644 error = parse_dynamic(lf); 645 if (error) 646 goto out; 647 link_elf_reloc_local(lf); 648 error = linker_load_dependencies(lf); 649 if (error) 650 goto out; 651 error = relocate_file(lf); 652 if (error) 653 goto out; 654 655 /* Try and load the symbol table if it's present. (you can strip it!) */ 656 nbytes = hdr->e_shnum * hdr->e_shentsize; 657 if (nbytes == 0 || hdr->e_shoff == 0) 658 goto nosyms; 659 shdr = kmalloc(nbytes, M_LINKER, M_WAITOK | M_ZERO); 660 error = vn_rdwr(UIO_READ, vp, 661 (caddr_t)shdr, nbytes, hdr->e_shoff, 662 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 663 if (error) 664 goto out; 665 symtabindex = -1; 666 symstrindex = -1; 667 for (i = 0; i < hdr->e_shnum; i++) { 668 if (shdr[i].sh_type == SHT_SYMTAB) { 669 symtabindex = i; 670 symstrindex = shdr[i].sh_link; 671 } 672 } 673 if (symtabindex < 0 || symstrindex < 0) 674 goto nosyms; 675 676 symcnt = shdr[symtabindex].sh_size; 677 ef->symbase = kmalloc(symcnt, M_LINKER, M_WAITOK); 678 strcnt = shdr[symstrindex].sh_size; 679 ef->strbase = kmalloc(strcnt, M_LINKER, M_WAITOK); 680 error = vn_rdwr(UIO_READ, vp, 681 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 682 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 683 if (error) 684 goto out; 685 error = vn_rdwr(UIO_READ, vp, 686 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 687 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 688 if (error) 689 goto out; 690 691 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 692 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 693 ef->ddbstrcnt = strcnt; 694 ef->ddbstrtab = ef->strbase; 695 696 nosyms: 697 698 *result = lf; 699 700 out: 701 if (error && lf) 702 linker_file_unload(lf); 703 if (shdr) 704 kfree(shdr, M_LINKER); 705 if (firstpage) 706 kfree(firstpage, M_LINKER); 707 vn_unlock(vp); 708 vn_close(vp, FREAD); 709 710 return error; 711 } 712 713 Elf_Addr 714 elf_relocaddr(linker_file_t lf, Elf_Addr x) 715 { 716 elf_file_t ef; 717 718 ef = lf->priv; 719 #if 0 720 if (x >= ef->pcpu_start && x < ef->pcpu_stop) 721 return ((x - ef->pcpu_start) + ef->pcpu_base); 722 #ifdef VIMAGE 723 if (x >= ef->vnet_start && x < ef->vnet_stop) 724 return ((x - ef->vnet_start) + ef->vnet_base); 725 #endif 726 #endif 727 return (x); 728 } 729 730 static void 731 link_elf_unload_file(linker_file_t file) 732 { 733 elf_file_t ef = file->priv; 734 735 if (ef) { 736 #ifdef SPARSE_MAPPING 737 if (ef->object) { 738 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 739 (vm_offset_t) ef->address 740 + (ef->object->size << PAGE_SHIFT)); 741 vm_object_deallocate(ef->object); 742 } 743 #else 744 if (ef->address) 745 kfree(ef->address, M_LINKER); 746 #endif 747 if (ef->symbase) 748 kfree(ef->symbase, M_LINKER); 749 if (ef->strbase) 750 kfree(ef->strbase, M_LINKER); 751 kfree(ef, M_LINKER); 752 } 753 } 754 755 static void 756 link_elf_unload_module(linker_file_t file) 757 { 758 elf_file_t ef = file->priv; 759 760 if (ef) 761 kfree(ef, M_LINKER); 762 if (file->filename) 763 preload_delete_name(file->filename); 764 } 765 766 static const char * 767 symbol_name(elf_file_t ef, Elf_Size r_info) 768 { 769 const Elf_Sym *ref; 770 771 if (ELF_R_SYM(r_info)) { 772 ref = ef->symtab + ELF_R_SYM(r_info); 773 return ef->strtab + ref->st_name; 774 } else 775 return NULL; 776 } 777 778 static int 779 relocate_file(linker_file_t lf) 780 { 781 elf_file_t ef = lf->priv; 782 const Elf_Rel *rellim; 783 const Elf_Rel *rel; 784 const Elf_Rela *relalim; 785 const Elf_Rela *rela; 786 const char *symname; 787 788 /* Perform relocations without addend if there are any: */ 789 rel = ef->rel; 790 if (rel) { 791 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 792 while (rel < rellim) { 793 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) { 794 symname = symbol_name(ef, rel->r_info); 795 kprintf("link_elf: symbol %s undefined\n", symname); 796 return ENOENT; 797 } 798 rel++; 799 } 800 } 801 802 /* Perform relocations with addend if there are any: */ 803 rela = ef->rela; 804 if (rela) { 805 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 806 while (rela < relalim) { 807 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) { 808 symname = symbol_name(ef, rela->r_info); 809 kprintf("link_elf: symbol %s undefined\n", symname); 810 return ENOENT; 811 } 812 rela++; 813 } 814 } 815 816 /* Perform PLT relocations without addend if there are any: */ 817 rel = ef->pltrel; 818 if (rel) { 819 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 820 while (rel < rellim) { 821 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) { 822 symname = symbol_name(ef, rel->r_info); 823 kprintf("link_elf: symbol %s undefined\n", symname); 824 return ENOENT; 825 } 826 rel++; 827 } 828 } 829 830 /* Perform relocations with addend if there are any: */ 831 rela = ef->pltrela; 832 if (rela) { 833 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 834 while (rela < relalim) { 835 symname = symbol_name(ef, rela->r_info); 836 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) { 837 kprintf("link_elf: symbol %s undefined\n", symname); 838 return ENOENT; 839 } 840 rela++; 841 } 842 } 843 844 return 0; 845 } 846 847 /* 848 * Hash function for symbol table lookup. Don't even think about changing 849 * this. It is specified by the System V ABI. 850 */ 851 static unsigned long 852 elf_hash(const char *name) 853 { 854 const unsigned char *p = (const unsigned char *) name; 855 unsigned long h = 0; 856 unsigned long g; 857 858 while (*p != '\0') { 859 h = (h << 4) + *p++; 860 if ((g = h & 0xf0000000) != 0) 861 h ^= g >> 24; 862 h &= ~g; 863 } 864 return h; 865 } 866 867 int 868 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 869 { 870 elf_file_t ef = lf->priv; 871 unsigned long symnum; 872 const Elf_Sym* symp; 873 const char *strp; 874 unsigned long hash; 875 int i; 876 877 /* If we don't have a hash, bail. */ 878 if (ef->buckets == NULL || ef->nbuckets == 0) { 879 kprintf("link_elf_lookup_symbol: missing symbol hash table\n"); 880 return ENOENT; 881 } 882 883 /* First, search hashed global symbols */ 884 hash = elf_hash(name); 885 symnum = ef->buckets[hash % ef->nbuckets]; 886 887 while (symnum != STN_UNDEF) { 888 if (symnum >= ef->nchains) { 889 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 890 return ENOENT; 891 } 892 893 symp = ef->symtab + symnum; 894 if (symp->st_name == 0) { 895 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 896 return ENOENT; 897 } 898 899 strp = ef->strtab + symp->st_name; 900 901 if (strcmp(name, strp) == 0) { 902 if (symp->st_shndx != SHN_UNDEF || 903 (symp->st_value != 0 && 904 ELF_ST_TYPE(symp->st_info) == STT_FUNC) 905 ) { 906 *sym = (c_linker_sym_t) symp; 907 return 0; 908 } else { 909 return ENOENT; 910 } 911 } 912 913 symnum = ef->chains[symnum]; 914 } 915 916 /* If we have not found it, look at the full table (if loaded) */ 917 if (ef->symtab == ef->ddbsymtab) 918 return ENOENT; 919 920 /* Exhaustive search */ 921 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 922 strp = ef->ddbstrtab + symp->st_name; 923 if (strcmp(name, strp) == 0) { 924 if (symp->st_shndx != SHN_UNDEF || 925 (symp->st_value != 0 && 926 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 927 *sym = (c_linker_sym_t) symp; 928 return 0; 929 } else { 930 return ENOENT; 931 } 932 } 933 } 934 return ENOENT; 935 } 936 937 static int 938 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t *symval) 939 { 940 elf_file_t ef = lf->priv; 941 const Elf_Sym *es = (const Elf_Sym *)sym; 942 943 if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) { 944 symval->name = ef->strtab + es->st_name; 945 symval->value = (caddr_t) ef->address + es->st_value; 946 symval->size = es->st_size; 947 return 0; 948 } 949 if (ef->symtab == ef->ddbsymtab) 950 return ENOENT; 951 if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) { 952 symval->name = ef->ddbstrtab + es->st_name; 953 symval->value = (caddr_t) ef->address + es->st_value; 954 symval->size = es->st_size; 955 return 0; 956 } 957 return ENOENT; 958 } 959 960 static int 961 link_elf_search_symbol(linker_file_t lf, caddr_t value, 962 c_linker_sym_t *sym, long *diffp) 963 { 964 elf_file_t ef = lf->priv; 965 u_long off = (uintptr_t)(void *)value; 966 u_long diff = off; 967 u_long st_value; 968 const Elf_Sym *es; 969 const Elf_Sym *best = 0; 970 int i; 971 972 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 973 if (es->st_name == 0) 974 continue; 975 st_value = es->st_value + (uintptr_t)(void *)ef->address; 976 if (off >= st_value) { 977 if (off - st_value < diff) { 978 diff = off - st_value; 979 best = es; 980 if (diff == 0) 981 break; 982 } else if (off - st_value == diff) { 983 best = es; 984 } 985 } 986 } 987 if (best == 0) 988 *diffp = off; 989 else 990 *diffp = diff; 991 *sym = (c_linker_sym_t) best; 992 993 return 0; 994 } 995 996 /* 997 * Look up a linker set on an ELF system. 998 */ 999 static int 1000 link_elf_lookup_set(linker_file_t lf, const char *name, 1001 void ***startp, void ***stopp, int *countp) 1002 { 1003 c_linker_sym_t sym; 1004 linker_symval_t symval; 1005 char *setsym; 1006 void **start, **stop; 1007 int len, error = 0, count; 1008 1009 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */ 1010 setsym = kmalloc(len, M_LINKER, M_WAITOK); 1011 1012 /* get address of first entry */ 1013 ksnprintf(setsym, len, "%s%s", "__start_set_", name); 1014 error = link_elf_lookup_symbol(lf, setsym, &sym); 1015 if (error) 1016 goto out; 1017 link_elf_symbol_values(lf, sym, &symval); 1018 if (symval.value == 0) { 1019 error = ESRCH; 1020 goto out; 1021 } 1022 start = (void **)symval.value; 1023 1024 /* get address of last entry */ 1025 ksnprintf(setsym, len, "%s%s", "__stop_set_", name); 1026 error = link_elf_lookup_symbol(lf, setsym, &sym); 1027 if (error) 1028 goto out; 1029 link_elf_symbol_values(lf, sym, &symval); 1030 if (symval.value == 0) { 1031 error = ESRCH; 1032 goto out; 1033 } 1034 stop = (void **)symval.value; 1035 1036 /* and the number of entries */ 1037 count = stop - start; 1038 1039 /* and copy out */ 1040 if (startp) 1041 *startp = start; 1042 if (stopp) 1043 *stopp = stop; 1044 if (countp) 1045 *countp = count; 1046 1047 out: 1048 kfree(setsym, M_LINKER); 1049 return error; 1050 } 1051 1052 /* 1053 * Symbol lookup function that can be used when the symbol index is known (ie 1054 * in relocations). It uses the symbol index instead of doing a fully fledged 1055 * hash table based lookup when such is valid. For example for local symbols. 1056 * This is not only more efficient, it's also more correct. It's not always 1057 * the case that the symbol can be found through the hash table. 1058 */ 1059 static int 1060 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *result) 1061 { 1062 elf_file_t ef = lf->priv; 1063 const Elf_Sym *sym; 1064 const char *symbol; 1065 1066 /* Don't even try to lookup the symbol if the index is bogus. */ 1067 if (symidx >= ef->nchains) 1068 return (ENOENT); 1069 1070 sym = ef->symtab + symidx; 1071 1072 /* 1073 * Don't do a full lookup when the symbol is local. It may even 1074 * fail because it may not be found through the hash table. 1075 */ 1076 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) { 1077 /* Force lookup failure when we have an insanity. */ 1078 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0) 1079 return (ENOENT); 1080 return ((Elf_Addr) ef->address + sym->st_value); 1081 } 1082 /* 1083 * XXX we can avoid doing a hash table based lookup for global 1084 * symbols as well. This however is not always valid, so we'll 1085 * just do it the hard way for now. Performance tweaks can 1086 * always be added. 1087 */ 1088 1089 symbol = ef->strtab + sym->st_name; 1090 1091 /* Force a lookup failure if the symbol name is bogus. */ 1092 if (*symbol == 0) 1093 return (ENOENT); 1094 1095 return (linker_file_lookup_symbol(lf, symbol, deps, (caddr_t *)result)); 1096 } 1097 static void 1098 link_elf_reloc_local(linker_file_t lf) 1099 { 1100 elf_file_t ef = lf->priv; 1101 const Elf_Rel *rellim; 1102 const Elf_Rel *rel; 1103 const Elf_Rela *relalim; 1104 const Elf_Rela *rela; 1105 1106 /* Perform relocations without addend if there are any: */ 1107 if ((rel = ef->rel) != NULL) { 1108 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 1109 while (rel < rellim) { 1110 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, 1111 elf_lookup); 1112 rel++; 1113 } 1114 } 1115 1116 /* Perform relocations with addend if there are any: */ 1117 if ((rela = ef->rela) != NULL) { 1118 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 1119 while (rela < relalim) { 1120 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, 1121 elf_lookup); 1122 rela++; 1123 } 1124 } 1125 } 1126