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 static int link_elf_preload_file(const char *, linker_file_t *); 54 static int link_elf_preload_finish(linker_file_t); 55 static int link_elf_load_file(const char*, linker_file_t*); 56 static int link_elf_lookup_symbol(linker_file_t, const char*, 57 c_linker_sym_t*); 58 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*); 59 static int link_elf_search_symbol(linker_file_t, caddr_t value, 60 c_linker_sym_t* sym, long* diffp); 61 62 static void link_elf_unload_file(linker_file_t); 63 static void link_elf_unload_module(linker_file_t); 64 static int link_elf_lookup_set(linker_file_t, const char *, 65 void ***, void ***, int *); 66 static int elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *); 67 static void link_elf_reloc_local(linker_file_t lf); 68 69 static struct linker_class_ops link_elf_class_ops = { 70 link_elf_load_file, 71 link_elf_preload_file, 72 }; 73 74 static struct linker_file_ops link_elf_file_ops = { 75 .lookup_symbol = link_elf_lookup_symbol, 76 .symbol_values = link_elf_symbol_values, 77 .search_symbol = link_elf_search_symbol, 78 .unload = link_elf_unload_file, 79 .lookup_set = link_elf_lookup_set 80 }; 81 82 static struct linker_file_ops link_elf_module_ops = { 83 .lookup_symbol = link_elf_lookup_symbol, 84 .symbol_values = link_elf_symbol_values, 85 .search_symbol = link_elf_search_symbol, 86 .preload_finish = link_elf_preload_finish, 87 .unload = link_elf_unload_module, 88 .lookup_set = link_elf_lookup_set, 89 }; 90 91 typedef struct elf_file { 92 caddr_t address; /* Relocation address */ 93 #ifdef SPARSE_MAPPING 94 vm_object_t object; /* VM object to hold file pages */ 95 #endif 96 const Elf_Dyn* dynamic; /* Symbol table etc. */ 97 Elf_Hashelt nbuckets; /* DT_HASH info */ 98 Elf_Hashelt nchains; 99 const Elf_Hashelt* buckets; 100 const Elf_Hashelt* chains; 101 caddr_t hash; 102 caddr_t strtab; /* DT_STRTAB */ 103 int strsz; /* DT_STRSZ */ 104 const Elf_Sym* symtab; /* DT_SYMTAB */ 105 Elf_Addr* got; /* DT_PLTGOT */ 106 const Elf_Rel* pltrel; /* DT_JMPREL */ 107 int pltrelsize; /* DT_PLTRELSZ */ 108 const Elf_Rela* pltrela; /* DT_JMPREL */ 109 int pltrelasize; /* DT_PLTRELSZ */ 110 const Elf_Rel* rel; /* DT_REL */ 111 int relsize; /* DT_RELSZ */ 112 const Elf_Rela* rela; /* DT_RELA */ 113 int relasize; /* DT_RELASZ */ 114 caddr_t modptr; 115 const Elf_Sym* ddbsymtab; /* The symbol table we are using */ 116 long ddbsymcnt; /* Number of symbols */ 117 caddr_t ddbstrtab; /* String table */ 118 long ddbstrcnt; /* number of bytes in string table */ 119 caddr_t symbase; /* malloc'ed symbold base */ 120 caddr_t strbase; /* malloc'ed string base */ 121 } *elf_file_t; 122 123 static int parse_dynamic(linker_file_t lf); 124 static int relocate_file(linker_file_t lf); 125 static int parse_module_symbols(linker_file_t lf); 126 127 /* 128 * The kernel symbol table starts here. 129 */ 130 extern struct _dynamic _DYNAMIC; 131 132 static void 133 link_elf_init(void* arg) 134 { 135 Elf_Dyn *dp; 136 caddr_t modptr, baseptr, sizeptr; 137 elf_file_t ef; 138 char *modname; 139 140 #if ELF_TARG_CLASS == ELFCLASS32 141 linker_add_class("elf32", NULL, &link_elf_class_ops); 142 #else 143 linker_add_class("elf64", NULL, &link_elf_class_ops); 144 #endif 145 146 dp = (Elf_Dyn*) &_DYNAMIC; 147 if (dp) { 148 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_INTWAIT | M_ZERO); 149 ef->address = 0; 150 #ifdef SPARSE_MAPPING 151 ef->object = 0; 152 #endif 153 ef->dynamic = dp; 154 modname = NULL; 155 modptr = preload_search_by_type("elf kernel"); 156 if (modptr) 157 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 158 if (modname == NULL) 159 modname = "kernel"; 160 linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops); 161 if (linker_kernel_file == NULL) 162 panic("link_elf_init: Can't create linker structures for kernel"); 163 parse_dynamic(linker_kernel_file); 164 linker_kernel_file->address = (caddr_t) KERNBASE; 165 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address; 166 167 if (modptr) { 168 ef->modptr = modptr; 169 baseptr = preload_search_info(modptr, MODINFO_ADDR); 170 if (baseptr) 171 linker_kernel_file->address = *(caddr_t *)baseptr; 172 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 173 if (sizeptr) 174 linker_kernel_file->size = *(size_t *)sizeptr; 175 } 176 parse_module_symbols(linker_kernel_file); 177 linker_current_file = linker_kernel_file; 178 linker_kernel_file->flags |= LINKER_FILE_LINKED; 179 } 180 } 181 182 SYSINIT(link_elf, SI_BOOT2_KLD, SI_ORDER_SECOND, link_elf_init, 0); 183 184 static int 185 parse_module_symbols(linker_file_t lf) 186 { 187 elf_file_t ef = lf->priv; 188 caddr_t pointer; 189 caddr_t ssym, esym, base; 190 caddr_t strtab; 191 int strcnt; 192 Elf_Sym* symtab; 193 int symcnt; 194 195 if (ef->modptr == NULL) 196 return 0; 197 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 198 if (pointer == NULL) 199 return 0; 200 ssym = *(caddr_t *)pointer; 201 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 202 if (pointer == NULL) 203 return 0; 204 esym = *(caddr_t *)pointer; 205 206 base = ssym; 207 208 symcnt = *(long *)base; 209 base += sizeof(long); 210 symtab = (Elf_Sym *)base; 211 base += roundup(symcnt, sizeof(long)); 212 213 if (base > esym || base < ssym) { 214 kprintf("Symbols are corrupt!\n"); 215 return EINVAL; 216 } 217 218 strcnt = *(long *)base; 219 base += sizeof(long); 220 strtab = base; 221 base += roundup(strcnt, sizeof(long)); 222 223 if (base > esym || base < ssym) { 224 kprintf("Symbols are corrupt!\n"); 225 return EINVAL; 226 } 227 228 ef->ddbsymtab = symtab; 229 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 230 ef->ddbstrtab = strtab; 231 ef->ddbstrcnt = strcnt; 232 233 return 0; 234 } 235 236 static int 237 parse_dynamic(linker_file_t lf) 238 { 239 elf_file_t ef = lf->priv; 240 const Elf_Dyn *dp; 241 int plttype = DT_REL; 242 243 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 244 switch (dp->d_tag) { 245 case DT_HASH: 246 { 247 /* From src/libexec/rtld-elf/rtld.c */ 248 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 249 (ef->address + dp->d_un.d_ptr); 250 ef->nbuckets = hashtab[0]; 251 ef->nchains = hashtab[1]; 252 ef->buckets = hashtab + 2; 253 ef->chains = ef->buckets + ef->nbuckets; 254 break; 255 } 256 case DT_STRTAB: 257 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 258 break; 259 case DT_STRSZ: 260 ef->strsz = dp->d_un.d_val; 261 break; 262 case DT_SYMTAB: 263 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 264 break; 265 case DT_SYMENT: 266 if (dp->d_un.d_val != sizeof(Elf_Sym)) 267 return ENOEXEC; 268 break; 269 case DT_PLTGOT: 270 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 271 break; 272 case DT_REL: 273 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 274 break; 275 case DT_RELSZ: 276 ef->relsize = dp->d_un.d_val; 277 break; 278 case DT_RELENT: 279 if (dp->d_un.d_val != sizeof(Elf_Rel)) 280 return ENOEXEC; 281 break; 282 case DT_JMPREL: 283 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 284 break; 285 case DT_PLTRELSZ: 286 ef->pltrelsize = dp->d_un.d_val; 287 break; 288 case DT_RELA: 289 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 290 break; 291 case DT_RELASZ: 292 ef->relasize = dp->d_un.d_val; 293 break; 294 case DT_RELAENT: 295 if (dp->d_un.d_val != sizeof(Elf_Rela)) 296 return ENOEXEC; 297 break; 298 case DT_PLTREL: 299 plttype = dp->d_un.d_val; 300 if (plttype != DT_REL && plttype != DT_RELA) 301 return ENOEXEC; 302 break; 303 } 304 } 305 306 if (plttype == DT_RELA) { 307 ef->pltrela = (const Elf_Rela *) ef->pltrel; 308 ef->pltrel = NULL; 309 ef->pltrelasize = ef->pltrelsize; 310 ef->pltrelsize = 0; 311 } 312 313 ef->ddbsymtab = ef->symtab; 314 ef->ddbsymcnt = ef->nchains; 315 ef->ddbstrtab = ef->strtab; 316 ef->ddbstrcnt = ef->strsz; 317 318 return 0; 319 } 320 321 static void 322 link_elf_error(const char *s) 323 { 324 kprintf("kldload: %s\n", s); 325 } 326 327 static int 328 link_elf_preload_file(const char *filename, linker_file_t *result) 329 { 330 caddr_t modptr, baseptr, sizeptr, dynptr; 331 char *type; 332 elf_file_t ef; 333 linker_file_t lf; 334 int error; 335 vm_offset_t dp; 336 337 /* 338 * Look to see if we have the module preloaded. 339 */ 340 modptr = preload_search_by_name(filename); 341 if (modptr == NULL) 342 return ENOENT; 343 344 /* It's preloaded, check we can handle it and collect information */ 345 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 346 baseptr = preload_search_info(modptr, MODINFO_ADDR); 347 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 348 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 349 if (type == NULL || 350 (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 && 351 strcmp(type, "elf module") != 0)) 352 return (EFTYPE); 353 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 354 return (EINVAL); 355 356 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 357 ef->modptr = modptr; 358 ef->address = *(caddr_t *)baseptr; 359 #ifdef SPARSE_MAPPING 360 ef->object = 0; 361 #endif 362 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 363 ef->dynamic = (Elf_Dyn *)dp; 364 lf = linker_make_file(filename, ef, &link_elf_module_ops); 365 if (lf == NULL) { 366 kfree(ef, M_LINKER); 367 return ENOMEM; 368 } 369 lf->address = ef->address; 370 lf->size = *(size_t *)sizeptr; 371 372 error = parse_dynamic(lf); 373 if (error) { 374 linker_file_unload(lf); 375 return error; 376 } 377 link_elf_reloc_local(lf); 378 *result = lf; 379 return (0); 380 } 381 382 static int 383 link_elf_preload_finish(linker_file_t lf) 384 { 385 int error; 386 387 error = relocate_file(lf); 388 if (error) 389 return error; 390 parse_module_symbols(lf); 391 392 return (0); 393 } 394 395 static int 396 link_elf_load_file(const char* filename, linker_file_t* result) 397 { 398 struct nlookupdata nd; 399 struct thread *td = curthread; /* XXX */ 400 struct proc *p = td->td_proc; 401 struct vnode *vp; 402 Elf_Ehdr *hdr; 403 caddr_t firstpage; 404 int nbytes, i; 405 Elf_Phdr *phdr; 406 Elf_Phdr *phlimit; 407 Elf_Phdr *segs[2]; 408 int nsegs; 409 Elf_Phdr *phdyn; 410 Elf_Phdr *phphdr; 411 caddr_t mapbase; 412 size_t mapsize; 413 Elf_Off base_offset; 414 Elf_Addr base_vaddr; 415 Elf_Addr base_vlimit; 416 int error = 0; 417 int resid; 418 elf_file_t ef; 419 linker_file_t lf; 420 char *pathname; 421 Elf_Shdr *shdr; 422 int symtabindex; 423 int symstrindex; 424 int symcnt; 425 int strcnt; 426 427 KKASSERT(p != NULL); 428 if (p->p_ucred == NULL) { 429 kprintf("link_elf_load_file: cannot load '%s' from filesystem" 430 " this early\n", filename); 431 return ENOENT; 432 } 433 shdr = NULL; 434 lf = NULL; 435 pathname = linker_search_path(filename); 436 if (pathname == NULL) 437 return ENOENT; 438 439 error = nlookup_init(&nd, pathname, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP); 440 if (error == 0) 441 error = vn_open(&nd, NULL, FREAD, 0); 442 kfree(pathname, M_LINKER); 443 if (error) { 444 nlookup_done(&nd); 445 return error; 446 } 447 vp = nd.nl_open_vp; 448 nd.nl_open_vp = NULL; 449 nlookup_done(&nd); 450 451 /* 452 * Read the elf header from the file. 453 */ 454 firstpage = kmalloc(PAGE_SIZE, M_LINKER, M_WAITOK); 455 hdr = (Elf_Ehdr *)firstpage; 456 error = vn_rdwr(UIO_READ, vp, firstpage, PAGE_SIZE, 0, 457 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 458 nbytes = PAGE_SIZE - resid; 459 if (error) 460 goto out; 461 462 if (!IS_ELF(*hdr)) { 463 error = ENOEXEC; 464 goto out; 465 } 466 467 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 468 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 469 link_elf_error("Unsupported file layout"); 470 error = ENOEXEC; 471 goto out; 472 } 473 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 474 || hdr->e_version != EV_CURRENT) { 475 link_elf_error("Unsupported file version"); 476 error = ENOEXEC; 477 goto out; 478 } 479 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 480 error = ENOSYS; 481 goto out; 482 } 483 if (hdr->e_machine != ELF_TARG_MACH) { 484 link_elf_error("Unsupported machine"); 485 error = ENOEXEC; 486 goto out; 487 } 488 489 /* 490 * We rely on the program header being in the first page. This is 491 * not strictly required by the ABI specification, but it seems to 492 * always true in practice. And, it simplifies things considerably. 493 */ 494 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 495 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 496 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 497 link_elf_error("Unreadable program headers"); 498 499 /* 500 * Scan the program header entries, and save key information. 501 * 502 * We rely on there being exactly two load segments, text and data, 503 * in that order. 504 */ 505 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 506 phlimit = phdr + hdr->e_phnum; 507 nsegs = 0; 508 phdyn = NULL; 509 phphdr = NULL; 510 while (phdr < phlimit) { 511 switch (phdr->p_type) { 512 513 case PT_LOAD: 514 if (nsegs == 2) { 515 link_elf_error("Too many sections"); 516 error = ENOEXEC; 517 goto out; 518 } 519 segs[nsegs] = phdr; 520 ++nsegs; 521 break; 522 523 case PT_PHDR: 524 phphdr = phdr; 525 break; 526 527 case PT_DYNAMIC: 528 phdyn = phdr; 529 break; 530 531 case PT_INTERP: 532 error = ENOSYS; 533 goto out; 534 } 535 536 ++phdr; 537 } 538 if (phdyn == NULL) { 539 link_elf_error("Object is not dynamically-linked"); 540 error = ENOEXEC; 541 goto out; 542 } 543 544 /* 545 * Allocate the entire address space of the object, to stake out our 546 * contiguous region, and to establish the base address for relocation. 547 */ 548 base_offset = trunc_page(segs[0]->p_offset); 549 base_vaddr = trunc_page(segs[0]->p_vaddr); 550 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); 551 mapsize = base_vlimit - base_vaddr; 552 553 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 554 #ifdef SPARSE_MAPPING 555 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 556 if (ef->object == NULL) { 557 kfree(ef, M_LINKER); 558 error = ENOMEM; 559 goto out; 560 } 561 vm_object_reference(ef->object); 562 ef->address = (caddr_t)vm_map_min(&kernel_map); 563 error = vm_map_find(&kernel_map, ef->object, 0, 564 (vm_offset_t *)&ef->address, mapsize, 565 1, 566 VM_MAPTYPE_NORMAL, 567 VM_PROT_ALL, VM_PROT_ALL, 568 0); 569 if (error) { 570 vm_object_deallocate(ef->object); 571 kfree(ef, M_LINKER); 572 goto out; 573 } 574 #else 575 ef->address = kmalloc(mapsize, M_LINKER, M_WAITOK); 576 #endif 577 mapbase = ef->address; 578 579 /* 580 * Read the text and data sections and zero the bss. 581 */ 582 for (i = 0; i < 2; i++) { 583 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 584 error = vn_rdwr(UIO_READ, vp, 585 segbase, segs[i]->p_filesz, segs[i]->p_offset, 586 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 587 if (error) { 588 #ifdef SPARSE_MAPPING 589 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 590 (vm_offset_t) ef->address 591 + (ef->object->size << PAGE_SHIFT)); 592 vm_object_deallocate(ef->object); 593 #else 594 kfree(ef->address, M_LINKER); 595 #endif 596 kfree(ef, M_LINKER); 597 goto out; 598 } 599 bzero(segbase + segs[i]->p_filesz, 600 segs[i]->p_memsz - segs[i]->p_filesz); 601 602 #ifdef SPARSE_MAPPING 603 /* 604 * Wire down the pages 605 */ 606 vm_map_wire(&kernel_map, 607 (vm_offset_t) segbase, 608 (vm_offset_t) segbase + segs[i]->p_memsz, 609 0); 610 #endif 611 } 612 613 ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 614 615 lf = linker_make_file(filename, ef, &link_elf_file_ops); 616 if (lf == NULL) { 617 #ifdef SPARSE_MAPPING 618 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 619 (vm_offset_t) ef->address 620 + (ef->object->size << PAGE_SHIFT)); 621 vm_object_deallocate(ef->object); 622 #else 623 kfree(ef->address, M_LINKER); 624 #endif 625 kfree(ef, M_LINKER); 626 error = ENOMEM; 627 goto out; 628 } 629 lf->address = ef->address; 630 lf->size = mapsize; 631 632 error = parse_dynamic(lf); 633 if (error) 634 goto out; 635 link_elf_reloc_local(lf); 636 error = linker_load_dependencies(lf); 637 if (error) 638 goto out; 639 error = relocate_file(lf); 640 if (error) 641 goto out; 642 643 /* Try and load the symbol table if it's present. (you can strip it!) */ 644 nbytes = hdr->e_shnum * hdr->e_shentsize; 645 if (nbytes == 0 || hdr->e_shoff == 0) 646 goto nosyms; 647 shdr = kmalloc(nbytes, M_LINKER, M_WAITOK | M_ZERO); 648 error = vn_rdwr(UIO_READ, vp, 649 (caddr_t)shdr, nbytes, hdr->e_shoff, 650 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 651 if (error) 652 goto out; 653 symtabindex = -1; 654 symstrindex = -1; 655 for (i = 0; i < hdr->e_shnum; i++) { 656 if (shdr[i].sh_type == SHT_SYMTAB) { 657 symtabindex = i; 658 symstrindex = shdr[i].sh_link; 659 } 660 } 661 if (symtabindex < 0 || symstrindex < 0) 662 goto nosyms; 663 664 symcnt = shdr[symtabindex].sh_size; 665 ef->symbase = kmalloc(symcnt, M_LINKER, M_WAITOK); 666 strcnt = shdr[symstrindex].sh_size; 667 ef->strbase = kmalloc(strcnt, M_LINKER, M_WAITOK); 668 error = vn_rdwr(UIO_READ, vp, 669 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 670 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 671 if (error) 672 goto out; 673 error = vn_rdwr(UIO_READ, vp, 674 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 675 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 676 if (error) 677 goto out; 678 679 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 680 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 681 ef->ddbstrcnt = strcnt; 682 ef->ddbstrtab = ef->strbase; 683 684 nosyms: 685 686 *result = lf; 687 688 out: 689 if (error && lf) 690 linker_file_unload(lf); 691 if (shdr) 692 kfree(shdr, M_LINKER); 693 if (firstpage) 694 kfree(firstpage, M_LINKER); 695 vn_unlock(vp); 696 vn_close(vp, FREAD); 697 698 return error; 699 } 700 701 Elf_Addr 702 elf_relocaddr(linker_file_t lf, Elf_Addr x) 703 { 704 elf_file_t ef; 705 706 ef = lf->priv; 707 #if 0 708 if (x >= ef->pcpu_start && x < ef->pcpu_stop) 709 return ((x - ef->pcpu_start) + ef->pcpu_base); 710 #ifdef VIMAGE 711 if (x >= ef->vnet_start && x < ef->vnet_stop) 712 return ((x - ef->vnet_start) + ef->vnet_base); 713 #endif 714 #endif 715 return (x); 716 } 717 718 static void 719 link_elf_unload_file(linker_file_t file) 720 { 721 elf_file_t ef = file->priv; 722 723 if (ef) { 724 #ifdef SPARSE_MAPPING 725 if (ef->object) { 726 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 727 (vm_offset_t) ef->address 728 + (ef->object->size << PAGE_SHIFT)); 729 vm_object_deallocate(ef->object); 730 } 731 #else 732 if (ef->address) 733 kfree(ef->address, M_LINKER); 734 #endif 735 if (ef->symbase) 736 kfree(ef->symbase, M_LINKER); 737 if (ef->strbase) 738 kfree(ef->strbase, M_LINKER); 739 kfree(ef, M_LINKER); 740 } 741 } 742 743 static void 744 link_elf_unload_module(linker_file_t file) 745 { 746 elf_file_t ef = file->priv; 747 748 if (ef) 749 kfree(ef, M_LINKER); 750 if (file->filename) 751 preload_delete_name(file->filename); 752 } 753 754 static const char * 755 symbol_name(elf_file_t ef, Elf_Size r_info) 756 { 757 const Elf_Sym *ref; 758 759 if (ELF_R_SYM(r_info)) { 760 ref = ef->symtab + ELF_R_SYM(r_info); 761 return ef->strtab + ref->st_name; 762 } else 763 return NULL; 764 } 765 766 static int 767 relocate_file(linker_file_t lf) 768 { 769 elf_file_t ef = lf->priv; 770 const Elf_Rel *rellim; 771 const Elf_Rel *rel; 772 const Elf_Rela *relalim; 773 const Elf_Rela *rela; 774 const char *symname; 775 776 /* Perform relocations without addend if there are any: */ 777 rel = ef->rel; 778 if (rel) { 779 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 780 while (rel < rellim) { 781 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) { 782 symname = symbol_name(ef, rel->r_info); 783 kprintf("link_elf: symbol %s undefined\n", symname); 784 return ENOENT; 785 } 786 rel++; 787 } 788 } 789 790 /* Perform relocations with addend if there are any: */ 791 rela = ef->rela; 792 if (rela) { 793 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 794 while (rela < relalim) { 795 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) { 796 symname = symbol_name(ef, rela->r_info); 797 kprintf("link_elf: symbol %s undefined\n", symname); 798 return ENOENT; 799 } 800 rela++; 801 } 802 } 803 804 /* Perform PLT relocations without addend if there are any: */ 805 rel = ef->pltrel; 806 if (rel) { 807 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 808 while (rel < rellim) { 809 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) { 810 symname = symbol_name(ef, rel->r_info); 811 kprintf("link_elf: symbol %s undefined\n", symname); 812 return ENOENT; 813 } 814 rel++; 815 } 816 } 817 818 /* Perform relocations with addend if there are any: */ 819 rela = ef->pltrela; 820 if (rela) { 821 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 822 while (rela < relalim) { 823 symname = symbol_name(ef, rela->r_info); 824 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) { 825 kprintf("link_elf: symbol %s undefined\n", symname); 826 return ENOENT; 827 } 828 rela++; 829 } 830 } 831 832 return 0; 833 } 834 835 /* 836 * Hash function for symbol table lookup. Don't even think about changing 837 * this. It is specified by the System V ABI. 838 */ 839 static unsigned long 840 elf_hash(const char *name) 841 { 842 const unsigned char *p = (const unsigned char *) name; 843 unsigned long h = 0; 844 unsigned long g; 845 846 while (*p != '\0') { 847 h = (h << 4) + *p++; 848 if ((g = h & 0xf0000000) != 0) 849 h ^= g >> 24; 850 h &= ~g; 851 } 852 return h; 853 } 854 855 int 856 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 857 { 858 elf_file_t ef = lf->priv; 859 unsigned long symnum; 860 const Elf_Sym* symp; 861 const char *strp; 862 unsigned long hash; 863 int i; 864 865 /* If we don't have a hash, bail. */ 866 if (ef->buckets == NULL || ef->nbuckets == 0) { 867 kprintf("link_elf_lookup_symbol: missing symbol hash table\n"); 868 return ENOENT; 869 } 870 871 /* First, search hashed global symbols */ 872 hash = elf_hash(name); 873 symnum = ef->buckets[hash % ef->nbuckets]; 874 875 while (symnum != STN_UNDEF) { 876 if (symnum >= ef->nchains) { 877 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 878 return ENOENT; 879 } 880 881 symp = ef->symtab + symnum; 882 if (symp->st_name == 0) { 883 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 884 return ENOENT; 885 } 886 887 strp = ef->strtab + symp->st_name; 888 889 if (strcmp(name, strp) == 0) { 890 if (symp->st_shndx != SHN_UNDEF || 891 (symp->st_value != 0 && 892 ELF_ST_TYPE(symp->st_info) == STT_FUNC) 893 ) { 894 *sym = (c_linker_sym_t) symp; 895 return 0; 896 } else { 897 return ENOENT; 898 } 899 } 900 901 symnum = ef->chains[symnum]; 902 } 903 904 /* If we have not found it, look at the full table (if loaded) */ 905 if (ef->symtab == ef->ddbsymtab) 906 return ENOENT; 907 908 /* Exhaustive search */ 909 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 910 strp = ef->ddbstrtab + symp->st_name; 911 if (strcmp(name, strp) == 0) { 912 if (symp->st_shndx != SHN_UNDEF || 913 (symp->st_value != 0 && 914 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 915 *sym = (c_linker_sym_t) symp; 916 return 0; 917 } else { 918 return ENOENT; 919 } 920 } 921 } 922 return ENOENT; 923 } 924 925 static int 926 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t *symval) 927 { 928 elf_file_t ef = lf->priv; 929 const Elf_Sym *es = (const Elf_Sym *)sym; 930 931 if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) { 932 symval->name = ef->strtab + es->st_name; 933 symval->value = (caddr_t) ef->address + es->st_value; 934 symval->size = es->st_size; 935 return 0; 936 } 937 if (ef->symtab == ef->ddbsymtab) 938 return ENOENT; 939 if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) { 940 symval->name = ef->ddbstrtab + es->st_name; 941 symval->value = (caddr_t) ef->address + es->st_value; 942 symval->size = es->st_size; 943 return 0; 944 } 945 return ENOENT; 946 } 947 948 static int 949 link_elf_search_symbol(linker_file_t lf, caddr_t value, 950 c_linker_sym_t *sym, long *diffp) 951 { 952 elf_file_t ef = lf->priv; 953 u_long off = (uintptr_t)(void *)value; 954 u_long diff = off; 955 u_long st_value; 956 const Elf_Sym *es; 957 const Elf_Sym *best = 0; 958 int i; 959 960 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 961 if (es->st_name == 0) 962 continue; 963 st_value = es->st_value + (uintptr_t)(void *)ef->address; 964 if (off >= st_value) { 965 if (off - st_value < diff) { 966 diff = off - st_value; 967 best = es; 968 if (diff == 0) 969 break; 970 } else if (off - st_value == diff) { 971 best = es; 972 } 973 } 974 } 975 if (best == 0) 976 *diffp = off; 977 else 978 *diffp = diff; 979 *sym = (c_linker_sym_t) best; 980 981 return 0; 982 } 983 984 /* 985 * Look up a linker set on an ELF system. 986 */ 987 static int 988 link_elf_lookup_set(linker_file_t lf, const char *name, 989 void ***startp, void ***stopp, int *countp) 990 { 991 c_linker_sym_t sym; 992 linker_symval_t symval; 993 char *setsym; 994 void **start, **stop; 995 int len, error = 0, count; 996 997 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */ 998 setsym = kmalloc(len, M_LINKER, M_WAITOK); 999 1000 /* get address of first entry */ 1001 ksnprintf(setsym, len, "%s%s", "__start_set_", name); 1002 error = link_elf_lookup_symbol(lf, setsym, &sym); 1003 if (error) 1004 goto out; 1005 link_elf_symbol_values(lf, sym, &symval); 1006 if (symval.value == 0) { 1007 error = ESRCH; 1008 goto out; 1009 } 1010 start = (void **)symval.value; 1011 1012 /* get address of last entry */ 1013 ksnprintf(setsym, len, "%s%s", "__stop_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 stop = (void **)symval.value; 1023 1024 /* and the number of entries */ 1025 count = stop - start; 1026 1027 /* and copy out */ 1028 if (startp) 1029 *startp = start; 1030 if (stopp) 1031 *stopp = stop; 1032 if (countp) 1033 *countp = count; 1034 1035 out: 1036 kfree(setsym, M_LINKER); 1037 return error; 1038 } 1039 1040 /* 1041 * Symbol lookup function that can be used when the symbol index is known (ie 1042 * in relocations). It uses the symbol index instead of doing a fully fledged 1043 * hash table based lookup when such is valid. For example for local symbols. 1044 * This is not only more efficient, it's also more correct. It's not always 1045 * the case that the symbol can be found through the hash table. 1046 */ 1047 static int 1048 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *result) 1049 { 1050 elf_file_t ef = lf->priv; 1051 const Elf_Sym *sym; 1052 const char *symbol; 1053 1054 /* Don't even try to lookup the symbol if the index is bogus. */ 1055 if (symidx >= ef->nchains) 1056 return (ENOENT); 1057 1058 sym = ef->symtab + symidx; 1059 1060 /* 1061 * Don't do a full lookup when the symbol is local. It may even 1062 * fail because it may not be found through the hash table. 1063 */ 1064 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) { 1065 /* Force lookup failure when we have an insanity. */ 1066 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0) 1067 return (ENOENT); 1068 return ((Elf_Addr) ef->address + sym->st_value); 1069 } 1070 /* 1071 * XXX we can avoid doing a hash table based lookup for global 1072 * symbols as well. This however is not always valid, so we'll 1073 * just do it the hard way for now. Performance tweaks can 1074 * always be added. 1075 */ 1076 1077 symbol = ef->strtab + sym->st_name; 1078 1079 /* Force a lookup failure if the symbol name is bogus. */ 1080 if (*symbol == 0) 1081 return (ENOENT); 1082 1083 return (linker_file_lookup_symbol(lf, symbol, deps, (caddr_t *)result)); 1084 } 1085 static void 1086 link_elf_reloc_local(linker_file_t lf) 1087 { 1088 elf_file_t ef = lf->priv; 1089 const Elf_Rel *rellim; 1090 const Elf_Rel *rel; 1091 const Elf_Rela *relalim; 1092 const Elf_Rela *rela; 1093 1094 /* Perform relocations without addend if there are any: */ 1095 if ((rel = ef->rel) != NULL) { 1096 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 1097 while (rel < rellim) { 1098 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, 1099 elf_lookup); 1100 rel++; 1101 } 1102 } 1103 1104 /* Perform relocations with addend if there are any: */ 1105 if ((rela = ef->rela) != NULL) { 1106 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 1107 while (rela < relalim) { 1108 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, 1109 elf_lookup); 1110 rela++; 1111 } 1112 } 1113 } 1114