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 1.28 2008/02/06 22:37:46 nth 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 static int link_elf_load_module(const char*, linker_file_t*); 54 static int link_elf_load_file(const char*, linker_file_t*); 55 static int link_elf_lookup_symbol(linker_file_t, const char*, 56 c_linker_sym_t*); 57 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*); 58 static int link_elf_search_symbol(linker_file_t, caddr_t value, 59 c_linker_sym_t* sym, long* diffp); 60 61 static void link_elf_unload_file(linker_file_t); 62 static void link_elf_unload_module(linker_file_t); 63 static int link_elf_lookup_set(linker_file_t, const char *, 64 void ***, void ***, int *); 65 66 static struct linker_class_ops link_elf_class_ops = { 67 link_elf_load_module, 68 }; 69 70 static struct linker_file_ops link_elf_file_ops = { 71 link_elf_lookup_symbol, 72 link_elf_symbol_values, 73 link_elf_search_symbol, 74 link_elf_unload_file, 75 link_elf_lookup_set 76 }; 77 78 static struct linker_file_ops link_elf_module_ops = { 79 link_elf_lookup_symbol, 80 link_elf_symbol_values, 81 link_elf_search_symbol, 82 link_elf_unload_module, 83 link_elf_lookup_set 84 }; 85 86 typedef struct elf_file { 87 caddr_t address; /* Relocation address */ 88 #ifdef SPARSE_MAPPING 89 vm_object_t object; /* VM object to hold file pages */ 90 #endif 91 const Elf_Dyn* dynamic; /* Symbol table etc. */ 92 Elf_Off nbuckets; /* DT_HASH info */ 93 Elf_Off nchains; 94 const Elf_Off* buckets; 95 const Elf_Off* 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 load_dependancies(linker_file_t lf); 120 static int relocate_file(linker_file_t lf); 121 static int parse_module_symbols(linker_file_t lf); 122 123 /* 124 * The kernel symbol table starts here. 125 */ 126 extern struct _dynamic _DYNAMIC; 127 128 static void 129 link_elf_init(void* arg) 130 { 131 Elf_Dyn *dp; 132 caddr_t modptr, baseptr, sizeptr; 133 elf_file_t ef; 134 char *modname; 135 136 #if ELF_TARG_CLASS == ELFCLASS32 137 linker_add_class("elf32", NULL, &link_elf_class_ops); 138 #else 139 linker_add_class("elf64", NULL, &link_elf_class_ops); 140 #endif 141 142 dp = (Elf_Dyn*) &_DYNAMIC; 143 if (dp) { 144 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_INTWAIT | M_ZERO); 145 ef->address = 0; 146 #ifdef SPARSE_MAPPING 147 ef->object = 0; 148 #endif 149 ef->dynamic = dp; 150 modname = NULL; 151 modptr = preload_search_by_type("elf kernel"); 152 if (modptr) 153 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 154 if (modname == NULL) 155 modname = "kernel"; 156 linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops); 157 if (linker_kernel_file == NULL) 158 panic("link_elf_init: Can't create linker structures for kernel"); 159 parse_dynamic(linker_kernel_file); 160 linker_kernel_file->address = (caddr_t) KERNBASE; 161 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address; 162 163 if (modptr) { 164 ef->modptr = modptr; 165 baseptr = preload_search_info(modptr, MODINFO_ADDR); 166 if (baseptr) 167 linker_kernel_file->address = *(caddr_t *)baseptr; 168 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 169 if (sizeptr) 170 linker_kernel_file->size = *(size_t *)sizeptr; 171 } 172 parse_module_symbols(linker_kernel_file); 173 linker_current_file = linker_kernel_file; 174 linker_kernel_file->flags |= LINKER_FILE_LINKED; 175 } 176 } 177 178 SYSINIT(link_elf, SI_BOOT2_KLD, SI_ORDER_SECOND, link_elf_init, 0); 179 180 static int 181 parse_module_symbols(linker_file_t lf) 182 { 183 elf_file_t ef = lf->priv; 184 caddr_t pointer; 185 caddr_t ssym, esym, base; 186 caddr_t strtab; 187 int strcnt; 188 Elf_Sym* symtab; 189 int symcnt; 190 191 if (ef->modptr == NULL) 192 return 0; 193 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 194 if (pointer == NULL) 195 return 0; 196 ssym = *(caddr_t *)pointer; 197 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 198 if (pointer == NULL) 199 return 0; 200 esym = *(caddr_t *)pointer; 201 202 base = ssym; 203 204 symcnt = *(long *)base; 205 base += sizeof(long); 206 symtab = (Elf_Sym *)base; 207 base += roundup(symcnt, sizeof(long)); 208 209 if (base > esym || base < ssym) { 210 kprintf("Symbols are corrupt!\n"); 211 return EINVAL; 212 } 213 214 strcnt = *(long *)base; 215 base += sizeof(long); 216 strtab = base; 217 base += roundup(strcnt, sizeof(long)); 218 219 if (base > esym || base < ssym) { 220 kprintf("Symbols are corrupt!\n"); 221 return EINVAL; 222 } 223 224 ef->ddbsymtab = symtab; 225 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 226 ef->ddbstrtab = strtab; 227 ef->ddbstrcnt = strcnt; 228 229 return 0; 230 } 231 232 static int 233 parse_dynamic(linker_file_t lf) 234 { 235 elf_file_t ef = lf->priv; 236 const Elf_Dyn *dp; 237 int plttype = DT_REL; 238 239 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 240 switch (dp->d_tag) { 241 case DT_HASH: 242 { 243 /* From src/libexec/rtld-elf/rtld.c */ 244 const Elf_Off *hashtab = (const Elf_Off *) 245 (ef->address + dp->d_un.d_ptr); 246 ef->nbuckets = hashtab[0]; 247 ef->nchains = hashtab[1]; 248 ef->buckets = hashtab + 2; 249 ef->chains = ef->buckets + ef->nbuckets; 250 break; 251 } 252 case DT_STRTAB: 253 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 254 break; 255 case DT_STRSZ: 256 ef->strsz = dp->d_un.d_val; 257 break; 258 case DT_SYMTAB: 259 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 260 break; 261 case DT_SYMENT: 262 if (dp->d_un.d_val != sizeof(Elf_Sym)) 263 return ENOEXEC; 264 break; 265 case DT_PLTGOT: 266 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 267 break; 268 case DT_REL: 269 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 270 break; 271 case DT_RELSZ: 272 ef->relsize = dp->d_un.d_val; 273 break; 274 case DT_RELENT: 275 if (dp->d_un.d_val != sizeof(Elf_Rel)) 276 return ENOEXEC; 277 break; 278 case DT_JMPREL: 279 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 280 break; 281 case DT_PLTRELSZ: 282 ef->pltrelsize = dp->d_un.d_val; 283 break; 284 case DT_RELA: 285 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 286 break; 287 case DT_RELASZ: 288 ef->relasize = dp->d_un.d_val; 289 break; 290 case DT_RELAENT: 291 if (dp->d_un.d_val != sizeof(Elf_Rela)) 292 return ENOEXEC; 293 break; 294 case DT_PLTREL: 295 plttype = dp->d_un.d_val; 296 if (plttype != DT_REL && plttype != DT_RELA) 297 return ENOEXEC; 298 break; 299 } 300 } 301 302 if (plttype == DT_RELA) { 303 ef->pltrela = (const Elf_Rela *) ef->pltrel; 304 ef->pltrel = NULL; 305 ef->pltrelasize = ef->pltrelsize; 306 ef->pltrelsize = 0; 307 } 308 309 ef->ddbsymtab = ef->symtab; 310 ef->ddbsymcnt = ef->nchains; 311 ef->ddbstrtab = ef->strtab; 312 ef->ddbstrcnt = ef->strsz; 313 314 return 0; 315 } 316 317 static void 318 link_elf_error(const char *s) 319 { 320 kprintf("kldload: %s\n", s); 321 } 322 323 static int 324 link_elf_load_module(const char *filename, linker_file_t *result) 325 { 326 caddr_t modptr, baseptr, sizeptr, dynptr; 327 char *type; 328 elf_file_t ef; 329 linker_file_t lf; 330 int error; 331 vm_offset_t dp; 332 333 /* 334 * Look to see if we have the module preloaded. 335 */ 336 modptr = preload_search_by_name(filename); 337 if (modptr == NULL) 338 return (link_elf_load_file(filename, result)); 339 340 /* It's preloaded, check we can handle it and collect information */ 341 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 342 baseptr = preload_search_info(modptr, MODINFO_ADDR); 343 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 344 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 345 if (type == NULL || strcmp(type, "elf module") != 0) 346 return (EFTYPE); 347 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 348 return (EINVAL); 349 350 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 351 ef->modptr = modptr; 352 ef->address = *(caddr_t *)baseptr; 353 #ifdef SPARSE_MAPPING 354 ef->object = 0; 355 #endif 356 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 357 ef->dynamic = (Elf_Dyn *)dp; 358 lf = linker_make_file(filename, ef, &link_elf_module_ops); 359 if (lf == NULL) { 360 kfree(ef, M_LINKER); 361 return ENOMEM; 362 } 363 lf->address = ef->address; 364 lf->size = *(size_t *)sizeptr; 365 366 error = parse_dynamic(lf); 367 if (error) { 368 linker_file_unload(lf); 369 return error; 370 } 371 error = load_dependancies(lf); 372 if (error) { 373 linker_file_unload(lf); 374 return error; 375 } 376 error = relocate_file(lf); 377 if (error) { 378 linker_file_unload(lf); 379 return error; 380 } 381 parse_module_symbols(lf); 382 lf->flags |= LINKER_FILE_LINKED; 383 *result = lf; 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 Elf_Phdr *phphdr; 403 caddr_t mapbase; 404 size_t mapsize; 405 Elf_Off base_offset; 406 Elf_Addr base_vaddr; 407 Elf_Addr base_vlimit; 408 int error = 0; 409 int resid; 410 elf_file_t ef; 411 linker_file_t lf; 412 char *pathname; 413 Elf_Shdr *shdr; 414 int symtabindex; 415 int symstrindex; 416 int symcnt; 417 int strcnt; 418 419 KKASSERT(p != NULL); 420 if (p->p_ucred == NULL) { 421 kprintf("link_elf_load_file: cannot load '%s' from filesystem" 422 " this early\n", filename); 423 return ENOENT; 424 } 425 shdr = NULL; 426 lf = NULL; 427 pathname = linker_search_path(filename); 428 if (pathname == NULL) 429 return ENOENT; 430 431 error = nlookup_init(&nd, pathname, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP); 432 if (error == 0) 433 error = vn_open(&nd, NULL, FREAD, 0); 434 kfree(pathname, M_LINKER); 435 if (error) { 436 nlookup_done(&nd); 437 return error; 438 } 439 vp = nd.nl_open_vp; 440 nd.nl_open_vp = NULL; 441 nlookup_done(&nd); 442 443 /* 444 * Read the elf header from the file. 445 */ 446 firstpage = kmalloc(PAGE_SIZE, M_LINKER, M_WAITOK); 447 hdr = (Elf_Ehdr *)firstpage; 448 error = vn_rdwr(UIO_READ, vp, firstpage, PAGE_SIZE, 0, 449 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 450 nbytes = PAGE_SIZE - resid; 451 if (error) 452 goto out; 453 454 if (!IS_ELF(*hdr)) { 455 error = ENOEXEC; 456 goto out; 457 } 458 459 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 460 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 461 link_elf_error("Unsupported file layout"); 462 error = ENOEXEC; 463 goto out; 464 } 465 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 466 || hdr->e_version != EV_CURRENT) { 467 link_elf_error("Unsupported file version"); 468 error = ENOEXEC; 469 goto out; 470 } 471 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 472 link_elf_error("Unsupported file type"); 473 error = ENOEXEC; 474 goto out; 475 } 476 if (hdr->e_machine != ELF_TARG_MACH) { 477 link_elf_error("Unsupported machine"); 478 error = ENOEXEC; 479 goto out; 480 } 481 482 /* 483 * We rely on the program header being in the first page. This is 484 * not strictly required by the ABI specification, but it seems to 485 * always true in practice. And, it simplifies things considerably. 486 */ 487 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 488 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 489 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 490 link_elf_error("Unreadable program headers"); 491 492 /* 493 * Scan the program header entries, and save key information. 494 * 495 * We rely on there being exactly two load segments, text and data, 496 * in that order. 497 */ 498 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 499 phlimit = phdr + hdr->e_phnum; 500 nsegs = 0; 501 phdyn = NULL; 502 phphdr = NULL; 503 while (phdr < phlimit) { 504 switch (phdr->p_type) { 505 506 case PT_LOAD: 507 if (nsegs == 2) { 508 link_elf_error("Too many sections"); 509 error = ENOEXEC; 510 goto out; 511 } 512 segs[nsegs] = phdr; 513 ++nsegs; 514 break; 515 516 case PT_PHDR: 517 phphdr = phdr; 518 break; 519 520 case PT_DYNAMIC: 521 phdyn = phdr; 522 break; 523 } 524 525 ++phdr; 526 } 527 if (phdyn == NULL) { 528 link_elf_error("Object is not dynamically-linked"); 529 error = ENOEXEC; 530 goto out; 531 } 532 533 /* 534 * Allocate the entire address space of the object, to stake out our 535 * contiguous region, and to establish the base address for relocation. 536 */ 537 base_offset = trunc_page(segs[0]->p_offset); 538 base_vaddr = trunc_page(segs[0]->p_vaddr); 539 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); 540 mapsize = base_vlimit - base_vaddr; 541 542 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 543 #ifdef SPARSE_MAPPING 544 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 545 if (ef->object == NULL) { 546 kfree(ef, M_LINKER); 547 error = ENOMEM; 548 goto out; 549 } 550 vm_object_reference(ef->object); 551 ef->address = (caddr_t)vm_map_min(&kernel_map); 552 error = vm_map_find(&kernel_map, ef->object, 0, 553 (vm_offset_t *)&ef->address, mapsize, 554 1, 555 VM_MAPTYPE_NORMAL, 556 VM_PROT_ALL, VM_PROT_ALL, 557 0); 558 if (error) { 559 vm_object_deallocate(ef->object); 560 kfree(ef, M_LINKER); 561 goto out; 562 } 563 #else 564 ef->address = kmalloc(mapsize, M_LINKER, M_WAITOK); 565 #endif 566 mapbase = ef->address; 567 568 /* 569 * Read the text and data sections and zero the bss. 570 */ 571 for (i = 0; i < 2; i++) { 572 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 573 error = vn_rdwr(UIO_READ, vp, 574 segbase, segs[i]->p_filesz, segs[i]->p_offset, 575 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 576 if (error) { 577 #ifdef SPARSE_MAPPING 578 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 579 (vm_offset_t) ef->address 580 + (ef->object->size << PAGE_SHIFT)); 581 vm_object_deallocate(ef->object); 582 #else 583 kfree(ef->address, M_LINKER); 584 #endif 585 kfree(ef, M_LINKER); 586 goto out; 587 } 588 bzero(segbase + segs[i]->p_filesz, 589 segs[i]->p_memsz - segs[i]->p_filesz); 590 591 #ifdef SPARSE_MAPPING 592 /* 593 * Wire down the pages 594 */ 595 vm_map_wire(&kernel_map, 596 (vm_offset_t) segbase, 597 (vm_offset_t) segbase + segs[i]->p_memsz, 598 0); 599 #endif 600 } 601 602 ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 603 604 lf = linker_make_file(filename, ef, &link_elf_file_ops); 605 if (lf == NULL) { 606 #ifdef SPARSE_MAPPING 607 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 608 (vm_offset_t) ef->address 609 + (ef->object->size << PAGE_SHIFT)); 610 vm_object_deallocate(ef->object); 611 #else 612 kfree(ef->address, M_LINKER); 613 #endif 614 kfree(ef, M_LINKER); 615 error = ENOMEM; 616 goto out; 617 } 618 lf->address = ef->address; 619 lf->size = mapsize; 620 621 error = parse_dynamic(lf); 622 if (error) 623 goto out; 624 error = load_dependancies(lf); 625 if (error) 626 goto out; 627 error = relocate_file(lf); 628 if (error) 629 goto out; 630 631 /* Try and load the symbol table if it's present. (you can strip it!) */ 632 nbytes = hdr->e_shnum * hdr->e_shentsize; 633 if (nbytes == 0 || hdr->e_shoff == 0) 634 goto nosyms; 635 shdr = kmalloc(nbytes, M_LINKER, M_WAITOK | M_ZERO); 636 error = vn_rdwr(UIO_READ, vp, 637 (caddr_t)shdr, nbytes, hdr->e_shoff, 638 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 639 if (error) 640 goto out; 641 symtabindex = -1; 642 symstrindex = -1; 643 for (i = 0; i < hdr->e_shnum; i++) { 644 if (shdr[i].sh_type == SHT_SYMTAB) { 645 symtabindex = i; 646 symstrindex = shdr[i].sh_link; 647 } 648 } 649 if (symtabindex < 0 || symstrindex < 0) 650 goto nosyms; 651 652 symcnt = shdr[symtabindex].sh_size; 653 ef->symbase = kmalloc(symcnt, M_LINKER, M_WAITOK); 654 strcnt = shdr[symstrindex].sh_size; 655 ef->strbase = kmalloc(strcnt, M_LINKER, M_WAITOK); 656 error = vn_rdwr(UIO_READ, vp, 657 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 658 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 659 if (error) 660 goto out; 661 error = vn_rdwr(UIO_READ, vp, 662 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 663 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 664 if (error) 665 goto out; 666 667 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 668 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 669 ef->ddbstrcnt = strcnt; 670 ef->ddbstrtab = ef->strbase; 671 672 lf->flags |= LINKER_FILE_LINKED; 673 674 nosyms: 675 676 *result = lf; 677 678 out: 679 if (error && lf) 680 linker_file_unload(lf); 681 if (shdr) 682 kfree(shdr, M_LINKER); 683 if (firstpage) 684 kfree(firstpage, M_LINKER); 685 vn_unlock(vp); 686 vn_close(vp, FREAD); 687 688 return error; 689 } 690 691 static void 692 link_elf_unload_file(linker_file_t file) 693 { 694 elf_file_t ef = file->priv; 695 696 if (ef) { 697 #ifdef SPARSE_MAPPING 698 if (ef->object) { 699 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 700 (vm_offset_t) ef->address 701 + (ef->object->size << PAGE_SHIFT)); 702 vm_object_deallocate(ef->object); 703 } 704 #else 705 if (ef->address) 706 kfree(ef->address, M_LINKER); 707 #endif 708 if (ef->symbase) 709 kfree(ef->symbase, M_LINKER); 710 if (ef->strbase) 711 kfree(ef->strbase, M_LINKER); 712 kfree(ef, M_LINKER); 713 } 714 } 715 716 static void 717 link_elf_unload_module(linker_file_t file) 718 { 719 elf_file_t ef = file->priv; 720 721 if (ef) 722 kfree(ef, M_LINKER); 723 if (file->filename) 724 preload_delete_name(file->filename); 725 } 726 727 static int 728 load_dependancies(linker_file_t lf) 729 { 730 elf_file_t ef = lf->priv; 731 linker_file_t lfdep; 732 char* name; 733 const Elf_Dyn *dp; 734 int error = 0; 735 736 /* 737 * All files are dependant on /kernel. 738 */ 739 if (linker_kernel_file) { 740 linker_kernel_file->refs++; 741 linker_file_add_dependancy(lf, linker_kernel_file); 742 } 743 744 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 745 if (dp->d_tag == DT_NEEDED) { 746 name = ef->strtab + dp->d_un.d_val; 747 748 error = linker_load_file(name, &lfdep); 749 if (error) 750 goto out; 751 linker_file_add_dependancy(lf, lfdep); 752 } 753 } 754 755 out: 756 return error; 757 } 758 759 static const char * 760 symbol_name(elf_file_t ef, Elf_Word r_info) 761 { 762 const Elf_Sym *ref; 763 764 if (ELF_R_SYM(r_info)) { 765 ref = ef->symtab + ELF_R_SYM(r_info); 766 return ef->strtab + ref->st_name; 767 } else 768 return NULL; 769 } 770 771 static int 772 relocate_file(linker_file_t lf) 773 { 774 elf_file_t ef = lf->priv; 775 const Elf_Rel *rellim; 776 const Elf_Rel *rel; 777 const Elf_Rela *relalim; 778 const Elf_Rela *rela; 779 const char *symname; 780 781 /* Perform relocations without addend if there are any: */ 782 rel = ef->rel; 783 if (rel) { 784 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 785 while (rel < rellim) { 786 symname = symbol_name(ef, rel->r_info); 787 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) { 788 kprintf("link_elf: symbol %s undefined\n", symname); 789 return ENOENT; 790 } 791 rel++; 792 } 793 } 794 795 /* Perform relocations with addend if there are any: */ 796 rela = ef->rela; 797 if (rela) { 798 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 799 while (rela < relalim) { 800 symname = symbol_name(ef, rela->r_info); 801 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) { 802 kprintf("link_elf: symbol %s undefined\n", symname); 803 return ENOENT; 804 } 805 rela++; 806 } 807 } 808 809 /* Perform PLT relocations without addend if there are any: */ 810 rel = ef->pltrel; 811 if (rel) { 812 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 813 while (rel < rellim) { 814 symname = symbol_name(ef, rel->r_info); 815 if (elf_reloc(lf, rel, ELF_RELOC_REL, symname)) { 816 kprintf("link_elf: symbol %s undefined\n", symname); 817 return ENOENT; 818 } 819 rel++; 820 } 821 } 822 823 /* Perform relocations with addend if there are any: */ 824 rela = ef->pltrela; 825 if (rela) { 826 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 827 while (rela < relalim) { 828 symname = symbol_name(ef, rela->r_info); 829 if (elf_reloc(lf, rela, ELF_RELOC_RELA, symname)) { 830 kprintf("link_elf: symbol %s undefined\n", symname); 831 return ENOENT; 832 } 833 rela++; 834 } 835 } 836 837 return 0; 838 } 839 840 /* 841 * Hash function for symbol table lookup. Don't even think about changing 842 * this. It is specified by the System V ABI. 843 */ 844 static unsigned long 845 elf_hash(const char *name) 846 { 847 const unsigned char *p = (const unsigned char *) name; 848 unsigned long h = 0; 849 unsigned long g; 850 851 while (*p != '\0') { 852 h = (h << 4) + *p++; 853 if ((g = h & 0xf0000000) != 0) 854 h ^= g >> 24; 855 h &= ~g; 856 } 857 return h; 858 } 859 860 int 861 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 862 { 863 elf_file_t ef = lf->priv; 864 unsigned long symnum; 865 const Elf_Sym* symp; 866 const char *strp; 867 unsigned long hash; 868 int i; 869 870 /* First, search hashed global symbols */ 871 hash = elf_hash(name); 872 symnum = ef->buckets[hash % ef->nbuckets]; 873 874 while (symnum != STN_UNDEF) { 875 if (symnum >= ef->nchains) { 876 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 877 return ENOENT; 878 } 879 880 symp = ef->symtab + symnum; 881 if (symp->st_name == 0) { 882 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 883 return ENOENT; 884 } 885 886 strp = ef->strtab + symp->st_name; 887 888 if (strcmp(name, strp) == 0) { 889 if (symp->st_shndx != SHN_UNDEF || 890 (symp->st_value != 0 && 891 ELF_ST_TYPE(symp->st_info) == STT_FUNC) 892 ) { 893 *sym = (c_linker_sym_t) symp; 894 return 0; 895 } else { 896 return ENOENT; 897 } 898 } 899 900 symnum = ef->chains[symnum]; 901 } 902 903 /* If we have not found it, look at the full table (if loaded) */ 904 if (ef->symtab == ef->ddbsymtab) 905 return ENOENT; 906 907 /* Exhaustive search */ 908 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 909 strp = ef->ddbstrtab + symp->st_name; 910 if (strcmp(name, strp) == 0) { 911 if (symp->st_shndx != SHN_UNDEF || 912 (symp->st_value != 0 && 913 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 914 *sym = (c_linker_sym_t) symp; 915 return 0; 916 } else { 917 return ENOENT; 918 } 919 } 920 } 921 return ENOENT; 922 } 923 924 static int 925 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t* symval) 926 { 927 elf_file_t ef = lf->priv; 928 const Elf_Sym* es = (const Elf_Sym*) sym; 929 930 if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) { 931 symval->name = ef->strtab + es->st_name; 932 symval->value = (caddr_t) ef->address + es->st_value; 933 symval->size = es->st_size; 934 return 0; 935 } 936 if (ef->symtab == ef->ddbsymtab) 937 return ENOENT; 938 if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) { 939 symval->name = ef->ddbstrtab + es->st_name; 940 symval->value = (caddr_t) ef->address + es->st_value; 941 symval->size = es->st_size; 942 return 0; 943 } 944 return ENOENT; 945 } 946 947 static int 948 link_elf_search_symbol(linker_file_t lf, caddr_t value, 949 c_linker_sym_t* sym, long* diffp) 950 { 951 elf_file_t ef = lf->priv; 952 u_long off = (uintptr_t) (void *) value; 953 u_long diff = off; 954 u_long st_value; 955 const Elf_Sym* es; 956 const Elf_Sym* best = 0; 957 int i; 958 959 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 960 if (es->st_name == 0) 961 continue; 962 st_value = es->st_value + (uintptr_t) (void *) ef->address; 963 if (off >= st_value) { 964 if (off - st_value < diff) { 965 diff = off - st_value; 966 best = es; 967 if (diff == 0) 968 break; 969 } else if (off - st_value == diff) { 970 best = es; 971 } 972 } 973 } 974 if (best == 0) 975 *diffp = off; 976 else 977 *diffp = diff; 978 *sym = (c_linker_sym_t) best; 979 980 return 0; 981 } 982 983 /* 984 * Look up a linker set on an ELF system. 985 */ 986 static int 987 link_elf_lookup_set(linker_file_t lf, const char *name, 988 void ***startp, void ***stopp, int *countp) 989 { 990 c_linker_sym_t sym; 991 linker_symval_t symval; 992 char *setsym; 993 void **start, **stop; 994 int len, error = 0, count; 995 996 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */ 997 setsym = kmalloc(len, M_LINKER, M_WAITOK); 998 999 /* get address of first entry */ 1000 ksnprintf(setsym, len, "%s%s", "__start_set_", name); 1001 error = link_elf_lookup_symbol(lf, setsym, &sym); 1002 if (error) 1003 goto out; 1004 link_elf_symbol_values(lf, sym, &symval); 1005 if (symval.value == 0) { 1006 error = ESRCH; 1007 goto out; 1008 } 1009 start = (void **)symval.value; 1010 1011 /* get address of last entry */ 1012 ksnprintf(setsym, len, "%s%s", "__stop_set_", name); 1013 error = link_elf_lookup_symbol(lf, setsym, &sym); 1014 if (error) 1015 goto out; 1016 link_elf_symbol_values(lf, sym, &symval); 1017 if (symval.value == 0) { 1018 error = ESRCH; 1019 goto out; 1020 } 1021 stop = (void **)symval.value; 1022 1023 /* and the number of entries */ 1024 count = stop - start; 1025 1026 /* and copy out */ 1027 if (startp) 1028 *startp = start; 1029 if (stopp) 1030 *stopp = stop; 1031 if (countp) 1032 *countp = count; 1033 1034 out: 1035 kfree(setsym, M_LINKER); 1036 return error; 1037 } 1038 1039