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 KKASSERT(p != NULL); 435 if (p->p_ucred == NULL) { 436 kprintf("link_elf_load_file: cannot load '%s' from filesystem" 437 " this early\n", filename); 438 return ENOENT; 439 } 440 shdr = NULL; 441 lf = NULL; 442 pathname = linker_search_path(filename); 443 if (pathname == NULL) 444 return ENOENT; 445 446 error = nlookup_init(&nd, pathname, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP); 447 if (error == 0) 448 error = vn_open(&nd, NULL, FREAD, 0); 449 kfree(pathname, M_LINKER); 450 if (error) { 451 nlookup_done(&nd); 452 return error; 453 } 454 vp = nd.nl_open_vp; 455 nd.nl_open_vp = NULL; 456 nlookup_done(&nd); 457 458 /* 459 * Read the elf header from the file. 460 */ 461 firstpage = kmalloc(PAGE_SIZE, M_LINKER, M_WAITOK); 462 hdr = (Elf_Ehdr *)firstpage; 463 error = vn_rdwr(UIO_READ, vp, firstpage, PAGE_SIZE, 0, 464 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 465 nbytes = PAGE_SIZE - resid; 466 if (error) 467 goto out; 468 469 if (!IS_ELF(*hdr)) { 470 error = ENOEXEC; 471 goto out; 472 } 473 474 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 475 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 476 link_elf_error("Unsupported file layout"); 477 error = ENOEXEC; 478 goto out; 479 } 480 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 481 || hdr->e_version != EV_CURRENT) { 482 link_elf_error("Unsupported file version"); 483 error = ENOEXEC; 484 goto out; 485 } 486 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 487 error = ENOSYS; 488 goto out; 489 } 490 if (hdr->e_machine != ELF_TARG_MACH) { 491 link_elf_error("Unsupported machine"); 492 error = ENOEXEC; 493 goto out; 494 } 495 496 /* 497 * We rely on the program header being in the first page. This is 498 * not strictly required by the ABI specification, but it seems to 499 * always true in practice. And, it simplifies things considerably. 500 */ 501 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 502 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 503 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 504 link_elf_error("Unreadable program headers"); 505 506 /* 507 * Scan the program header entries, and save key information. 508 * 509 * We rely on there being exactly two load segments, text and data, 510 * in that order. 511 */ 512 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 513 phlimit = phdr + hdr->e_phnum; 514 nsegs = 0; 515 phdyn = NULL; 516 phphdr = NULL; 517 while (phdr < phlimit) { 518 switch (phdr->p_type) { 519 520 case PT_LOAD: 521 if (nsegs == 2) { 522 link_elf_error("Too many sections"); 523 error = ENOEXEC; 524 goto out; 525 } 526 segs[nsegs] = phdr; 527 ++nsegs; 528 break; 529 530 case PT_PHDR: 531 phphdr = phdr; 532 break; 533 534 case PT_DYNAMIC: 535 phdyn = phdr; 536 break; 537 538 case PT_INTERP: 539 error = ENOSYS; 540 goto out; 541 } 542 543 ++phdr; 544 } 545 if (phdyn == NULL) { 546 link_elf_error("Object is not dynamically-linked"); 547 error = ENOEXEC; 548 goto out; 549 } 550 551 /* 552 * Allocate the entire address space of the object, to stake out our 553 * contiguous region, and to establish the base address for relocation. 554 */ 555 base_offset = trunc_page(segs[0]->p_offset); 556 base_vaddr = trunc_page(segs[0]->p_vaddr); 557 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); 558 mapsize = base_vlimit - base_vaddr; 559 560 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 561 #ifdef SPARSE_MAPPING 562 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 563 if (ef->object == NULL) { 564 kfree(ef, M_LINKER); 565 error = ENOMEM; 566 goto out; 567 } 568 vm_object_reference(ef->object); 569 ef->address = (caddr_t)vm_map_min(&kernel_map); 570 error = vm_map_find(&kernel_map, ef->object, 0, 571 (vm_offset_t *)&ef->address, 572 mapsize, PAGE_SIZE, 573 1, VM_MAPTYPE_NORMAL, 574 VM_PROT_ALL, VM_PROT_ALL, 575 0); 576 if (error) { 577 vm_object_deallocate(ef->object); 578 kfree(ef, M_LINKER); 579 goto out; 580 } 581 #else 582 ef->address = kmalloc(mapsize, M_LINKER, M_WAITOK); 583 #endif 584 mapbase = ef->address; 585 586 /* 587 * Read the text and data sections and zero the bss. 588 */ 589 for (i = 0; i < 2; i++) { 590 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 591 error = vn_rdwr(UIO_READ, vp, 592 segbase, segs[i]->p_filesz, segs[i]->p_offset, 593 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 594 if (error) { 595 #ifdef SPARSE_MAPPING 596 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 597 (vm_offset_t) ef->address 598 + (ef->object->size << PAGE_SHIFT)); 599 vm_object_deallocate(ef->object); 600 #else 601 kfree(ef->address, M_LINKER); 602 #endif 603 kfree(ef, M_LINKER); 604 goto out; 605 } 606 bzero(segbase + segs[i]->p_filesz, 607 segs[i]->p_memsz - segs[i]->p_filesz); 608 609 #ifdef SPARSE_MAPPING 610 /* 611 * Wire down the pages 612 */ 613 vm_map_wire(&kernel_map, 614 (vm_offset_t) segbase, 615 (vm_offset_t) segbase + segs[i]->p_memsz, 616 0); 617 #endif 618 } 619 620 ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 621 622 lf = linker_make_file(filename, ef, &link_elf_file_ops); 623 if (lf == NULL) { 624 #ifdef SPARSE_MAPPING 625 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 626 (vm_offset_t) ef->address 627 + (ef->object->size << PAGE_SHIFT)); 628 vm_object_deallocate(ef->object); 629 #else 630 kfree(ef->address, M_LINKER); 631 #endif 632 kfree(ef, M_LINKER); 633 error = ENOMEM; 634 goto out; 635 } 636 lf->address = ef->address; 637 lf->size = mapsize; 638 639 error = parse_dynamic(lf); 640 if (error) 641 goto out; 642 link_elf_reloc_local(lf); 643 error = linker_load_dependencies(lf); 644 if (error) 645 goto out; 646 error = relocate_file(lf); 647 if (error) 648 goto out; 649 650 /* Try and load the symbol table if it's present. (you can strip it!) */ 651 nbytes = hdr->e_shnum * hdr->e_shentsize; 652 if (nbytes == 0 || hdr->e_shoff == 0) 653 goto nosyms; 654 shdr = kmalloc(nbytes, M_LINKER, M_WAITOK | M_ZERO); 655 error = vn_rdwr(UIO_READ, vp, 656 (caddr_t)shdr, nbytes, hdr->e_shoff, 657 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 658 if (error) 659 goto out; 660 symtabindex = -1; 661 symstrindex = -1; 662 for (i = 0; i < hdr->e_shnum; i++) { 663 if (shdr[i].sh_type == SHT_SYMTAB) { 664 symtabindex = i; 665 symstrindex = shdr[i].sh_link; 666 } 667 } 668 if (symtabindex < 0 || symstrindex < 0) 669 goto nosyms; 670 671 symcnt = shdr[symtabindex].sh_size; 672 ef->symbase = kmalloc(symcnt, M_LINKER, M_WAITOK); 673 strcnt = shdr[symstrindex].sh_size; 674 ef->strbase = kmalloc(strcnt, M_LINKER, M_WAITOK); 675 error = vn_rdwr(UIO_READ, vp, 676 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 677 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 678 if (error) 679 goto out; 680 error = vn_rdwr(UIO_READ, vp, 681 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 682 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 683 if (error) 684 goto out; 685 686 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 687 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 688 ef->ddbstrcnt = strcnt; 689 ef->ddbstrtab = ef->strbase; 690 691 nosyms: 692 693 *result = lf; 694 695 out: 696 if (error && lf) 697 linker_file_unload(lf); 698 if (shdr) 699 kfree(shdr, M_LINKER); 700 if (firstpage) 701 kfree(firstpage, M_LINKER); 702 vn_unlock(vp); 703 vn_close(vp, FREAD); 704 705 return error; 706 } 707 708 Elf_Addr 709 elf_relocaddr(linker_file_t lf, Elf_Addr x) 710 { 711 elf_file_t ef; 712 713 ef = lf->priv; 714 #if 0 715 if (x >= ef->pcpu_start && x < ef->pcpu_stop) 716 return ((x - ef->pcpu_start) + ef->pcpu_base); 717 #ifdef VIMAGE 718 if (x >= ef->vnet_start && x < ef->vnet_stop) 719 return ((x - ef->vnet_start) + ef->vnet_base); 720 #endif 721 #endif 722 return (x); 723 } 724 725 static void 726 link_elf_unload_file(linker_file_t file) 727 { 728 elf_file_t ef = file->priv; 729 730 if (ef) { 731 #ifdef SPARSE_MAPPING 732 if (ef->object) { 733 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 734 (vm_offset_t) ef->address 735 + (ef->object->size << PAGE_SHIFT)); 736 vm_object_deallocate(ef->object); 737 } 738 #else 739 if (ef->address) 740 kfree(ef->address, M_LINKER); 741 #endif 742 if (ef->symbase) 743 kfree(ef->symbase, M_LINKER); 744 if (ef->strbase) 745 kfree(ef->strbase, M_LINKER); 746 kfree(ef, M_LINKER); 747 } 748 } 749 750 static void 751 link_elf_unload_module(linker_file_t file) 752 { 753 elf_file_t ef = file->priv; 754 755 if (ef) 756 kfree(ef, M_LINKER); 757 if (file->filename) 758 preload_delete_name(file->filename); 759 } 760 761 static const char * 762 symbol_name(elf_file_t ef, Elf_Size r_info) 763 { 764 const Elf_Sym *ref; 765 766 if (ELF_R_SYM(r_info)) { 767 ref = ef->symtab + ELF_R_SYM(r_info); 768 return ef->strtab + ref->st_name; 769 } else 770 return NULL; 771 } 772 773 static int 774 relocate_file(linker_file_t lf) 775 { 776 elf_file_t ef = lf->priv; 777 const Elf_Rel *rellim; 778 const Elf_Rel *rel; 779 const Elf_Rela *relalim; 780 const Elf_Rela *rela; 781 const char *symname; 782 783 /* Perform relocations without addend if there are any: */ 784 rel = ef->rel; 785 if (rel) { 786 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 787 while (rel < rellim) { 788 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) { 789 symname = symbol_name(ef, rel->r_info); 790 kprintf("link_elf: symbol %s undefined\n", symname); 791 return ENOENT; 792 } 793 rel++; 794 } 795 } 796 797 /* Perform relocations with addend if there are any: */ 798 rela = ef->rela; 799 if (rela) { 800 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 801 while (rela < relalim) { 802 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) { 803 symname = symbol_name(ef, rela->r_info); 804 kprintf("link_elf: symbol %s undefined\n", symname); 805 return ENOENT; 806 } 807 rela++; 808 } 809 } 810 811 /* Perform PLT relocations without addend if there are any: */ 812 rel = ef->pltrel; 813 if (rel) { 814 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 815 while (rel < rellim) { 816 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) { 817 symname = symbol_name(ef, rel->r_info); 818 kprintf("link_elf: symbol %s undefined\n", symname); 819 return ENOENT; 820 } 821 rel++; 822 } 823 } 824 825 /* Perform relocations with addend if there are any: */ 826 rela = ef->pltrela; 827 if (rela) { 828 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 829 while (rela < relalim) { 830 symname = symbol_name(ef, rela->r_info); 831 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) { 832 kprintf("link_elf: symbol %s undefined\n", symname); 833 return ENOENT; 834 } 835 rela++; 836 } 837 } 838 839 return 0; 840 } 841 842 /* 843 * Hash function for symbol table lookup. Don't even think about changing 844 * this. It is specified by the System V ABI. 845 */ 846 static unsigned long 847 elf_hash(const char *name) 848 { 849 const unsigned char *p = (const unsigned char *) name; 850 unsigned long h = 0; 851 unsigned long g; 852 853 while (*p != '\0') { 854 h = (h << 4) + *p++; 855 if ((g = h & 0xf0000000) != 0) 856 h ^= g >> 24; 857 h &= ~g; 858 } 859 return h; 860 } 861 862 int 863 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 864 { 865 elf_file_t ef = lf->priv; 866 unsigned long symnum; 867 const Elf_Sym* symp; 868 const char *strp; 869 unsigned long hash; 870 int i; 871 872 /* If we don't have a hash, bail. */ 873 if (ef->buckets == NULL || ef->nbuckets == 0) { 874 kprintf("link_elf_lookup_symbol: missing symbol hash table\n"); 875 return ENOENT; 876 } 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 kprintf("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 kprintf("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 ) { 901 *sym = (c_linker_sym_t) symp; 902 return 0; 903 } else { 904 return ENOENT; 905 } 906 } 907 908 symnum = ef->chains[symnum]; 909 } 910 911 /* If we have not found it, look at the full table (if loaded) */ 912 if (ef->symtab == ef->ddbsymtab) 913 return ENOENT; 914 915 /* Exhaustive search */ 916 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 917 strp = ef->ddbstrtab + symp->st_name; 918 if (strcmp(name, strp) == 0) { 919 if (symp->st_shndx != SHN_UNDEF || 920 (symp->st_value != 0 && 921 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 922 *sym = (c_linker_sym_t) symp; 923 return 0; 924 } else { 925 return ENOENT; 926 } 927 } 928 } 929 return ENOENT; 930 } 931 932 static int 933 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t *symval) 934 { 935 elf_file_t ef = lf->priv; 936 const Elf_Sym *es = (const Elf_Sym *)sym; 937 938 if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) { 939 symval->name = ef->strtab + es->st_name; 940 symval->value = (caddr_t) ef->address + es->st_value; 941 symval->size = es->st_size; 942 return 0; 943 } 944 if (ef->symtab == ef->ddbsymtab) 945 return ENOENT; 946 if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) { 947 symval->name = ef->ddbstrtab + es->st_name; 948 symval->value = (caddr_t) ef->address + es->st_value; 949 symval->size = es->st_size; 950 return 0; 951 } 952 return ENOENT; 953 } 954 955 static int 956 link_elf_search_symbol(linker_file_t lf, caddr_t value, 957 c_linker_sym_t *sym, long *diffp) 958 { 959 elf_file_t ef = lf->priv; 960 u_long off = (uintptr_t)(void *)value; 961 u_long diff = off; 962 u_long st_value; 963 const Elf_Sym *es; 964 const Elf_Sym *best = 0; 965 int i; 966 967 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 968 if (es->st_name == 0) 969 continue; 970 st_value = es->st_value + (uintptr_t)(void *)ef->address; 971 if (off >= st_value) { 972 if (off - st_value < diff) { 973 diff = off - st_value; 974 best = es; 975 if (diff == 0) 976 break; 977 } else if (off - st_value == diff) { 978 best = es; 979 } 980 } 981 } 982 if (best == 0) 983 *diffp = off; 984 else 985 *diffp = diff; 986 *sym = (c_linker_sym_t) best; 987 988 return 0; 989 } 990 991 /* 992 * Look up a linker set on an ELF system. 993 */ 994 static int 995 link_elf_lookup_set(linker_file_t lf, const char *name, 996 void ***startp, void ***stopp, int *countp) 997 { 998 c_linker_sym_t sym; 999 linker_symval_t symval; 1000 char *setsym; 1001 void **start, **stop; 1002 int len, error = 0, count; 1003 1004 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */ 1005 setsym = kmalloc(len, M_LINKER, M_WAITOK); 1006 1007 /* get address of first entry */ 1008 ksnprintf(setsym, len, "%s%s", "__start_set_", name); 1009 error = link_elf_lookup_symbol(lf, setsym, &sym); 1010 if (error) 1011 goto out; 1012 link_elf_symbol_values(lf, sym, &symval); 1013 if (symval.value == 0) { 1014 error = ESRCH; 1015 goto out; 1016 } 1017 start = (void **)symval.value; 1018 1019 /* get address of last entry */ 1020 ksnprintf(setsym, len, "%s%s", "__stop_set_", name); 1021 error = link_elf_lookup_symbol(lf, setsym, &sym); 1022 if (error) 1023 goto out; 1024 link_elf_symbol_values(lf, sym, &symval); 1025 if (symval.value == 0) { 1026 error = ESRCH; 1027 goto out; 1028 } 1029 stop = (void **)symval.value; 1030 1031 /* and the number of entries */ 1032 count = stop - start; 1033 1034 /* and copy out */ 1035 if (startp) 1036 *startp = start; 1037 if (stopp) 1038 *stopp = stop; 1039 if (countp) 1040 *countp = count; 1041 1042 out: 1043 kfree(setsym, M_LINKER); 1044 return error; 1045 } 1046 1047 /* 1048 * Symbol lookup function that can be used when the symbol index is known (ie 1049 * in relocations). It uses the symbol index instead of doing a fully fledged 1050 * hash table based lookup when such is valid. For example for local symbols. 1051 * This is not only more efficient, it's also more correct. It's not always 1052 * the case that the symbol can be found through the hash table. 1053 */ 1054 static int 1055 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *result) 1056 { 1057 elf_file_t ef = lf->priv; 1058 const Elf_Sym *sym; 1059 const char *symbol; 1060 1061 /* Don't even try to lookup the symbol if the index is bogus. */ 1062 if (symidx >= ef->nchains) 1063 return (ENOENT); 1064 1065 sym = ef->symtab + symidx; 1066 1067 /* 1068 * Don't do a full lookup when the symbol is local. It may even 1069 * fail because it may not be found through the hash table. 1070 */ 1071 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) { 1072 /* Force lookup failure when we have an insanity. */ 1073 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0) 1074 return (ENOENT); 1075 return ((Elf_Addr) ef->address + sym->st_value); 1076 } 1077 /* 1078 * XXX we can avoid doing a hash table based lookup for global 1079 * symbols as well. This however is not always valid, so we'll 1080 * just do it the hard way for now. Performance tweaks can 1081 * always be added. 1082 */ 1083 1084 symbol = ef->strtab + sym->st_name; 1085 1086 /* Force a lookup failure if the symbol name is bogus. */ 1087 if (*symbol == 0) 1088 return (ENOENT); 1089 1090 return (linker_file_lookup_symbol(lf, symbol, deps, (caddr_t *)result)); 1091 } 1092 static void 1093 link_elf_reloc_local(linker_file_t lf) 1094 { 1095 elf_file_t ef = lf->priv; 1096 const Elf_Rel *rellim; 1097 const Elf_Rel *rel; 1098 const Elf_Rela *relalim; 1099 const Elf_Rela *rela; 1100 1101 /* Perform relocations without addend if there are any: */ 1102 if ((rel = ef->rel) != NULL) { 1103 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 1104 while (rel < rellim) { 1105 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, 1106 elf_lookup); 1107 rel++; 1108 } 1109 } 1110 1111 /* Perform relocations with addend if there are any: */ 1112 if ((rela = ef->rela) != NULL) { 1113 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 1114 while (rela < relalim) { 1115 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, 1116 elf_lookup); 1117 rela++; 1118 } 1119 } 1120 } 1121