1 /*- 2 * Copyright (c) 1998 Doug Rabson 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: src/sys/kern/link_elf.c,v 1.24 1999/12/24 15:33:36 bde Exp $ 27 */ 28 29 #include <sys/param.h> 30 #include <sys/kernel.h> 31 #include <sys/systm.h> 32 #include <sys/malloc.h> 33 #include <sys/proc.h> 34 #include <sys/nlookup.h> 35 #include <sys/fcntl.h> 36 #include <sys/vnode.h> 37 #include <sys/linker.h> 38 #include <machine/elf.h> 39 40 #include <vm/vm.h> 41 #include <vm/vm_param.h> 42 #include <vm/vm_zone.h> 43 #include <sys/lock.h> 44 #ifdef SPARSE_MAPPING 45 #include <vm/vm_object.h> 46 #include <vm/vm_kern.h> 47 #include <vm/vm_extern.h> 48 #endif 49 #include <vm/pmap.h> 50 #include <vm/vm_map.h> 51 52 #if defined(__amd64__) && defined(_KERNEL_VIRTUAL) 53 #include <stdio.h> 54 #endif 55 56 static int link_elf_preload_file(const char *, linker_file_t *); 57 static int link_elf_preload_finish(linker_file_t); 58 static int link_elf_load_file(const char*, linker_file_t*); 59 static int link_elf_lookup_symbol(linker_file_t, const char*, 60 c_linker_sym_t*); 61 static int link_elf_symbol_values(linker_file_t, c_linker_sym_t, linker_symval_t*); 62 static int link_elf_search_symbol(linker_file_t, caddr_t value, 63 c_linker_sym_t* sym, long* diffp); 64 65 static void link_elf_unload_file(linker_file_t); 66 static void link_elf_unload_module(linker_file_t); 67 static int link_elf_lookup_set(linker_file_t, const char *, 68 void ***, void ***, int *); 69 static int elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *); 70 static void link_elf_reloc_local(linker_file_t lf); 71 72 static struct linker_class_ops link_elf_class_ops = { 73 link_elf_load_file, 74 link_elf_preload_file, 75 }; 76 77 static struct linker_file_ops link_elf_file_ops = { 78 .lookup_symbol = link_elf_lookup_symbol, 79 .symbol_values = link_elf_symbol_values, 80 .search_symbol = link_elf_search_symbol, 81 .unload = link_elf_unload_file, 82 .lookup_set = link_elf_lookup_set 83 }; 84 85 static struct linker_file_ops link_elf_module_ops = { 86 .lookup_symbol = link_elf_lookup_symbol, 87 .symbol_values = link_elf_symbol_values, 88 .search_symbol = link_elf_search_symbol, 89 .preload_finish = link_elf_preload_finish, 90 .unload = link_elf_unload_module, 91 .lookup_set = link_elf_lookup_set, 92 }; 93 94 typedef struct elf_file { 95 caddr_t address; /* Relocation address */ 96 #ifdef SPARSE_MAPPING 97 vm_object_t object; /* VM object to hold file pages */ 98 #endif 99 const Elf_Dyn* dynamic; /* Symbol table etc. */ 100 Elf_Hashelt nbuckets; /* DT_HASH info */ 101 Elf_Hashelt nchains; 102 const Elf_Hashelt* buckets; 103 const Elf_Hashelt* chains; 104 caddr_t hash; 105 caddr_t strtab; /* DT_STRTAB */ 106 int strsz; /* DT_STRSZ */ 107 const Elf_Sym* symtab; /* DT_SYMTAB */ 108 Elf_Addr* got; /* DT_PLTGOT */ 109 const Elf_Rel* pltrel; /* DT_JMPREL */ 110 int pltrelsize; /* DT_PLTRELSZ */ 111 const Elf_Rela* pltrela; /* DT_JMPREL */ 112 int pltrelasize; /* DT_PLTRELSZ */ 113 const Elf_Rel* rel; /* DT_REL */ 114 int relsize; /* DT_RELSZ */ 115 const Elf_Rela* rela; /* DT_RELA */ 116 int relasize; /* DT_RELASZ */ 117 caddr_t modptr; 118 const Elf_Sym* ddbsymtab; /* The symbol table we are using */ 119 long ddbsymcnt; /* Number of symbols */ 120 caddr_t ddbstrtab; /* String table */ 121 long ddbstrcnt; /* number of bytes in string table */ 122 caddr_t symbase; /* malloc'ed symbold base */ 123 caddr_t strbase; /* malloc'ed string base */ 124 } *elf_file_t; 125 126 static int parse_dynamic(linker_file_t lf); 127 static int relocate_file(linker_file_t lf); 128 static int parse_module_symbols(linker_file_t lf); 129 130 /* 131 * The kernel symbol table starts here. 132 */ 133 extern struct _dynamic _DYNAMIC; 134 135 static void 136 link_elf_init(void* arg) 137 { 138 Elf_Dyn *dp; 139 caddr_t modptr, baseptr, sizeptr; 140 elf_file_t ef; 141 char *modname; 142 143 #if ELF_TARG_CLASS == ELFCLASS32 144 linker_add_class("elf32", NULL, &link_elf_class_ops); 145 #else 146 linker_add_class("elf64", NULL, &link_elf_class_ops); 147 #endif 148 149 dp = (Elf_Dyn*) &_DYNAMIC; 150 if (dp) { 151 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_INTWAIT | M_ZERO); 152 ef->address = 0; 153 #ifdef SPARSE_MAPPING 154 ef->object = 0; 155 #endif 156 ef->dynamic = dp; 157 modname = NULL; 158 modptr = preload_search_by_type("elf kernel"); 159 if (modptr) 160 modname = (char *)preload_search_info(modptr, MODINFO_NAME); 161 if (modname == NULL) 162 modname = "kernel"; 163 linker_kernel_file = linker_make_file(modname, ef, &link_elf_file_ops); 164 if (linker_kernel_file == NULL) 165 panic("link_elf_init: Can't create linker structures for kernel"); 166 parse_dynamic(linker_kernel_file); 167 #if defined(__amd64__) && defined(_KERNEL_VIRTUAL) 168 fprintf(stderr, "WARNING: KERNBASE being used\n"); 169 #endif 170 linker_kernel_file->address = (caddr_t) KERNBASE; 171 linker_kernel_file->size = -(intptr_t)linker_kernel_file->address; 172 173 if (modptr) { 174 ef->modptr = modptr; 175 baseptr = preload_search_info(modptr, MODINFO_ADDR); 176 if (baseptr) 177 linker_kernel_file->address = *(caddr_t *)baseptr; 178 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 179 if (sizeptr) 180 linker_kernel_file->size = *(size_t *)sizeptr; 181 } 182 parse_module_symbols(linker_kernel_file); 183 linker_current_file = linker_kernel_file; 184 linker_kernel_file->flags |= LINKER_FILE_LINKED; 185 } 186 } 187 188 SYSINIT(link_elf, SI_BOOT2_KLD, SI_ORDER_SECOND, link_elf_init, 0); 189 190 static int 191 parse_module_symbols(linker_file_t lf) 192 { 193 elf_file_t ef = lf->priv; 194 caddr_t pointer; 195 caddr_t ssym, esym, base; 196 caddr_t strtab; 197 int strcnt; 198 Elf_Sym* symtab; 199 int symcnt; 200 201 if (ef->modptr == NULL) 202 return 0; 203 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_SSYM); 204 if (pointer == NULL) 205 return 0; 206 ssym = *(caddr_t *)pointer; 207 pointer = preload_search_info(ef->modptr, MODINFO_METADATA|MODINFOMD_ESYM); 208 if (pointer == NULL) 209 return 0; 210 esym = *(caddr_t *)pointer; 211 212 base = ssym; 213 214 symcnt = *(long *)base; 215 base += sizeof(long); 216 symtab = (Elf_Sym *)base; 217 base += roundup(symcnt, sizeof(long)); 218 219 if (base > esym || base < ssym) { 220 kprintf("Symbols are corrupt!\n"); 221 return EINVAL; 222 } 223 224 strcnt = *(long *)base; 225 base += sizeof(long); 226 strtab = base; 227 base += roundup(strcnt, sizeof(long)); 228 229 if (base > esym || base < ssym) { 230 kprintf("Symbols are corrupt!\n"); 231 return EINVAL; 232 } 233 234 ef->ddbsymtab = symtab; 235 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 236 ef->ddbstrtab = strtab; 237 ef->ddbstrcnt = strcnt; 238 239 return 0; 240 } 241 242 static int 243 parse_dynamic(linker_file_t lf) 244 { 245 elf_file_t ef = lf->priv; 246 const Elf_Dyn *dp; 247 int plttype = DT_REL; 248 249 for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { 250 switch (dp->d_tag) { 251 case DT_HASH: 252 { 253 /* From src/libexec/rtld-elf/rtld.c */ 254 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 255 (ef->address + dp->d_un.d_ptr); 256 ef->nbuckets = hashtab[0]; 257 ef->nchains = hashtab[1]; 258 ef->buckets = hashtab + 2; 259 ef->chains = ef->buckets + ef->nbuckets; 260 break; 261 } 262 case DT_STRTAB: 263 ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); 264 break; 265 case DT_STRSZ: 266 ef->strsz = dp->d_un.d_val; 267 break; 268 case DT_SYMTAB: 269 ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); 270 break; 271 case DT_SYMENT: 272 if (dp->d_un.d_val != sizeof(Elf_Sym)) 273 return ENOEXEC; 274 break; 275 case DT_PLTGOT: 276 ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); 277 break; 278 case DT_REL: 279 ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 280 break; 281 case DT_RELSZ: 282 ef->relsize = dp->d_un.d_val; 283 break; 284 case DT_RELENT: 285 if (dp->d_un.d_val != sizeof(Elf_Rel)) 286 return ENOEXEC; 287 break; 288 case DT_JMPREL: 289 ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); 290 break; 291 case DT_PLTRELSZ: 292 ef->pltrelsize = dp->d_un.d_val; 293 break; 294 case DT_RELA: 295 ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); 296 break; 297 case DT_RELASZ: 298 ef->relasize = dp->d_un.d_val; 299 break; 300 case DT_RELAENT: 301 if (dp->d_un.d_val != sizeof(Elf_Rela)) 302 return ENOEXEC; 303 break; 304 case DT_PLTREL: 305 plttype = dp->d_un.d_val; 306 if (plttype != DT_REL && plttype != DT_RELA) 307 return ENOEXEC; 308 break; 309 } 310 } 311 312 if (plttype == DT_RELA) { 313 ef->pltrela = (const Elf_Rela *) ef->pltrel; 314 ef->pltrel = NULL; 315 ef->pltrelasize = ef->pltrelsize; 316 ef->pltrelsize = 0; 317 } 318 319 ef->ddbsymtab = ef->symtab; 320 ef->ddbsymcnt = ef->nchains; 321 ef->ddbstrtab = ef->strtab; 322 ef->ddbstrcnt = ef->strsz; 323 324 return 0; 325 } 326 327 static void 328 link_elf_error(const char *s) 329 { 330 kprintf("kldload: %s\n", s); 331 } 332 333 static int 334 link_elf_preload_file(const char *filename, linker_file_t *result) 335 { 336 caddr_t modptr, baseptr, sizeptr, dynptr; 337 char *type; 338 elf_file_t ef; 339 linker_file_t lf; 340 int error; 341 vm_offset_t dp; 342 343 /* 344 * Look to see if we have the module preloaded. 345 */ 346 modptr = preload_search_by_name(filename); 347 if (modptr == NULL) 348 return ENOENT; 349 350 /* It's preloaded, check we can handle it and collect information */ 351 type = (char *)preload_search_info(modptr, MODINFO_TYPE); 352 baseptr = preload_search_info(modptr, MODINFO_ADDR); 353 sizeptr = preload_search_info(modptr, MODINFO_SIZE); 354 dynptr = preload_search_info(modptr, MODINFO_METADATA|MODINFOMD_DYNAMIC); 355 if (type == NULL || 356 (strcmp(type, "elf" __XSTRING(__ELF_WORD_SIZE) " module") != 0 && 357 strcmp(type, "elf module") != 0)) 358 return (EFTYPE); 359 if (baseptr == NULL || sizeptr == NULL || dynptr == NULL) 360 return (EINVAL); 361 362 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 363 ef->modptr = modptr; 364 ef->address = *(caddr_t *)baseptr; 365 #ifdef SPARSE_MAPPING 366 ef->object = 0; 367 #endif 368 dp = (vm_offset_t)ef->address + *(vm_offset_t *)dynptr; 369 ef->dynamic = (Elf_Dyn *)dp; 370 lf = linker_make_file(filename, ef, &link_elf_module_ops); 371 if (lf == NULL) { 372 kfree(ef, M_LINKER); 373 return ENOMEM; 374 } 375 lf->address = ef->address; 376 lf->size = *(size_t *)sizeptr; 377 378 error = parse_dynamic(lf); 379 if (error) { 380 linker_file_unload(lf); 381 return error; 382 } 383 link_elf_reloc_local(lf); 384 *result = lf; 385 return (0); 386 } 387 388 static int 389 link_elf_preload_finish(linker_file_t lf) 390 { 391 int error; 392 393 error = relocate_file(lf); 394 if (error) 395 return error; 396 parse_module_symbols(lf); 397 398 return (0); 399 } 400 401 static int 402 link_elf_load_file(const char* filename, linker_file_t* result) 403 { 404 struct nlookupdata nd; 405 struct thread *td = curthread; /* XXX */ 406 struct proc *p = td->td_proc; 407 struct vnode *vp; 408 Elf_Ehdr *hdr; 409 caddr_t firstpage; 410 int nbytes, i; 411 Elf_Phdr *phdr; 412 Elf_Phdr *phlimit; 413 Elf_Phdr *segs[2]; 414 int nsegs; 415 Elf_Phdr *phdyn; 416 Elf_Phdr *phphdr; 417 caddr_t mapbase; 418 size_t mapsize; 419 Elf_Off base_offset; 420 Elf_Addr base_vaddr; 421 Elf_Addr base_vlimit; 422 int error = 0; 423 int resid; 424 elf_file_t ef; 425 linker_file_t lf; 426 char *pathname; 427 Elf_Shdr *shdr; 428 int symtabindex; 429 int symstrindex; 430 int symcnt; 431 int strcnt; 432 433 /* XXX Hack for firmware loading where p == NULL */ 434 if (p == NULL) { 435 p = &proc0; 436 } 437 438 KKASSERT(p != NULL); 439 if (p->p_ucred == NULL) { 440 kprintf("link_elf_load_file: cannot load '%s' from filesystem" 441 " this early\n", filename); 442 return ENOENT; 443 } 444 shdr = NULL; 445 lf = NULL; 446 pathname = linker_search_path(filename); 447 if (pathname == NULL) 448 return ENOENT; 449 450 error = nlookup_init(&nd, pathname, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP); 451 if (error == 0) 452 error = vn_open(&nd, NULL, FREAD, 0); 453 kfree(pathname, M_LINKER); 454 if (error) { 455 nlookup_done(&nd); 456 return error; 457 } 458 vp = nd.nl_open_vp; 459 nd.nl_open_vp = NULL; 460 nlookup_done(&nd); 461 462 /* 463 * Read the elf header from the file. 464 */ 465 firstpage = kmalloc(PAGE_SIZE, M_LINKER, M_WAITOK); 466 hdr = (Elf_Ehdr *)firstpage; 467 error = vn_rdwr(UIO_READ, vp, firstpage, PAGE_SIZE, 0, 468 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 469 nbytes = PAGE_SIZE - resid; 470 if (error) 471 goto out; 472 473 if (!IS_ELF(*hdr)) { 474 error = ENOEXEC; 475 goto out; 476 } 477 478 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 479 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 480 link_elf_error("Unsupported file layout"); 481 error = ENOEXEC; 482 goto out; 483 } 484 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 485 || hdr->e_version != EV_CURRENT) { 486 link_elf_error("Unsupported file version"); 487 error = ENOEXEC; 488 goto out; 489 } 490 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 491 error = ENOSYS; 492 goto out; 493 } 494 if (hdr->e_machine != ELF_TARG_MACH) { 495 link_elf_error("Unsupported machine"); 496 error = ENOEXEC; 497 goto out; 498 } 499 500 /* 501 * We rely on the program header being in the first page. This is 502 * not strictly required by the ABI specification, but it seems to 503 * always true in practice. And, it simplifies things considerably. 504 */ 505 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 506 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 507 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 508 link_elf_error("Unreadable program headers"); 509 510 /* 511 * Scan the program header entries, and save key information. 512 * 513 * We rely on there being exactly two load segments, text and data, 514 * in that order. 515 */ 516 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 517 phlimit = phdr + hdr->e_phnum; 518 nsegs = 0; 519 phdyn = NULL; 520 phphdr = NULL; 521 while (phdr < phlimit) { 522 switch (phdr->p_type) { 523 524 case PT_LOAD: 525 if (nsegs == 2) { 526 link_elf_error("Too many sections"); 527 error = ENOEXEC; 528 goto out; 529 } 530 segs[nsegs] = phdr; 531 ++nsegs; 532 break; 533 534 case PT_PHDR: 535 phphdr = phdr; 536 break; 537 538 case PT_DYNAMIC: 539 phdyn = phdr; 540 break; 541 542 case PT_INTERP: 543 error = ENOSYS; 544 goto out; 545 } 546 547 ++phdr; 548 } 549 if (phdyn == NULL) { 550 link_elf_error("Object is not dynamically-linked"); 551 error = ENOEXEC; 552 goto out; 553 } 554 555 /* 556 * Allocate the entire address space of the object, to stake out our 557 * contiguous region, and to establish the base address for relocation. 558 */ 559 base_offset = trunc_page(segs[0]->p_offset); 560 base_vaddr = trunc_page(segs[0]->p_vaddr); 561 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); 562 mapsize = base_vlimit - base_vaddr; 563 564 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 565 #ifdef SPARSE_MAPPING 566 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 567 if (ef->object == NULL) { 568 kfree(ef, M_LINKER); 569 error = ENOMEM; 570 goto out; 571 } 572 vm_object_hold(ef->object); 573 vm_object_reference_locked(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 vm_object_drop(ef->object); 582 if (error) { 583 vm_object_deallocate(ef->object); 584 kfree(ef, M_LINKER); 585 goto out; 586 } 587 #else 588 ef->address = kmalloc(mapsize, M_LINKER, M_WAITOK); 589 #endif 590 mapbase = ef->address; 591 592 /* 593 * Read the text and data sections and zero the bss. 594 */ 595 for (i = 0; i < 2; i++) { 596 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 597 error = vn_rdwr(UIO_READ, vp, 598 segbase, segs[i]->p_filesz, segs[i]->p_offset, 599 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 600 if (error) { 601 #ifdef SPARSE_MAPPING 602 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 603 (vm_offset_t) ef->address 604 + (ef->object->size << PAGE_SHIFT)); 605 vm_object_deallocate(ef->object); 606 #else 607 kfree(ef->address, M_LINKER); 608 #endif 609 kfree(ef, M_LINKER); 610 goto out; 611 } 612 bzero(segbase + segs[i]->p_filesz, 613 segs[i]->p_memsz - segs[i]->p_filesz); 614 615 #ifdef SPARSE_MAPPING 616 /* 617 * Wire down the pages 618 */ 619 vm_map_wire(&kernel_map, 620 (vm_offset_t) segbase, 621 (vm_offset_t) segbase + segs[i]->p_memsz, 622 0); 623 #endif 624 } 625 626 ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 627 628 lf = linker_make_file(filename, ef, &link_elf_file_ops); 629 if (lf == NULL) { 630 #ifdef SPARSE_MAPPING 631 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 632 (vm_offset_t) ef->address 633 + (ef->object->size << PAGE_SHIFT)); 634 vm_object_deallocate(ef->object); 635 #else 636 kfree(ef->address, M_LINKER); 637 #endif 638 kfree(ef, M_LINKER); 639 error = ENOMEM; 640 goto out; 641 } 642 lf->address = ef->address; 643 lf->size = mapsize; 644 645 error = parse_dynamic(lf); 646 if (error) 647 goto out; 648 link_elf_reloc_local(lf); 649 error = linker_load_dependencies(lf); 650 if (error) 651 goto out; 652 error = relocate_file(lf); 653 if (error) 654 goto out; 655 656 /* Try and load the symbol table if it's present. (you can strip it!) */ 657 nbytes = hdr->e_shnum * hdr->e_shentsize; 658 if (nbytes == 0 || hdr->e_shoff == 0) 659 goto nosyms; 660 shdr = kmalloc(nbytes, M_LINKER, M_WAITOK | M_ZERO); 661 error = vn_rdwr(UIO_READ, vp, 662 (caddr_t)shdr, nbytes, hdr->e_shoff, 663 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 664 if (error) 665 goto out; 666 symtabindex = -1; 667 symstrindex = -1; 668 for (i = 0; i < hdr->e_shnum; i++) { 669 if (shdr[i].sh_type == SHT_SYMTAB) { 670 symtabindex = i; 671 symstrindex = shdr[i].sh_link; 672 } 673 } 674 if (symtabindex < 0 || symstrindex < 0) 675 goto nosyms; 676 677 symcnt = shdr[symtabindex].sh_size; 678 ef->symbase = kmalloc(symcnt, M_LINKER, M_WAITOK); 679 strcnt = shdr[symstrindex].sh_size; 680 ef->strbase = kmalloc(strcnt, M_LINKER, M_WAITOK); 681 error = vn_rdwr(UIO_READ, vp, 682 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 683 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 684 if (error) 685 goto out; 686 error = vn_rdwr(UIO_READ, vp, 687 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 688 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 689 if (error) 690 goto out; 691 692 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 693 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 694 ef->ddbstrcnt = strcnt; 695 ef->ddbstrtab = ef->strbase; 696 697 nosyms: 698 699 *result = lf; 700 701 out: 702 if (error && lf) 703 linker_file_unload(lf); 704 if (shdr) 705 kfree(shdr, M_LINKER); 706 if (firstpage) 707 kfree(firstpage, M_LINKER); 708 vn_unlock(vp); 709 vn_close(vp, FREAD); 710 711 return error; 712 } 713 714 Elf_Addr 715 elf_relocaddr(linker_file_t lf, Elf_Addr x) 716 { 717 elf_file_t ef; 718 719 ef = lf->priv; 720 #if 0 721 if (x >= ef->pcpu_start && x < ef->pcpu_stop) 722 return ((x - ef->pcpu_start) + ef->pcpu_base); 723 #ifdef VIMAGE 724 if (x >= ef->vnet_start && x < ef->vnet_stop) 725 return ((x - ef->vnet_start) + ef->vnet_base); 726 #endif 727 #endif 728 return (x); 729 } 730 731 static void 732 link_elf_unload_file(linker_file_t file) 733 { 734 elf_file_t ef = file->priv; 735 736 if (ef) { 737 #ifdef SPARSE_MAPPING 738 if (ef->object) { 739 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 740 (vm_offset_t) ef->address 741 + (ef->object->size << PAGE_SHIFT)); 742 vm_object_deallocate(ef->object); 743 } 744 #else 745 if (ef->address) 746 kfree(ef->address, M_LINKER); 747 #endif 748 if (ef->symbase) 749 kfree(ef->symbase, M_LINKER); 750 if (ef->strbase) 751 kfree(ef->strbase, M_LINKER); 752 kfree(ef, M_LINKER); 753 } 754 } 755 756 static void 757 link_elf_unload_module(linker_file_t file) 758 { 759 elf_file_t ef = file->priv; 760 761 if (ef) 762 kfree(ef, M_LINKER); 763 if (file->filename) 764 preload_delete_name(file->filename); 765 } 766 767 static const char * 768 symbol_name(elf_file_t ef, Elf_Size r_info) 769 { 770 const Elf_Sym *ref; 771 772 if (ELF_R_SYM(r_info)) { 773 ref = ef->symtab + ELF_R_SYM(r_info); 774 return ef->strtab + ref->st_name; 775 } else 776 return NULL; 777 } 778 779 static int 780 relocate_file(linker_file_t lf) 781 { 782 elf_file_t ef = lf->priv; 783 const Elf_Rel *rellim; 784 const Elf_Rel *rel; 785 const Elf_Rela *relalim; 786 const Elf_Rela *rela; 787 const char *symname; 788 789 /* Perform relocations without addend if there are any: */ 790 rel = ef->rel; 791 if (rel) { 792 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 793 while (rel < rellim) { 794 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) { 795 symname = symbol_name(ef, rel->r_info); 796 kprintf("link_elf: symbol %s undefined\n", symname); 797 return ENOENT; 798 } 799 rel++; 800 } 801 } 802 803 /* Perform relocations with addend if there are any: */ 804 rela = ef->rela; 805 if (rela) { 806 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 807 while (rela < relalim) { 808 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) { 809 symname = symbol_name(ef, rela->r_info); 810 kprintf("link_elf: symbol %s undefined\n", symname); 811 return ENOENT; 812 } 813 rela++; 814 } 815 } 816 817 /* Perform PLT relocations without addend if there are any: */ 818 rel = ef->pltrel; 819 if (rel) { 820 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 821 while (rel < rellim) { 822 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) { 823 symname = symbol_name(ef, rel->r_info); 824 kprintf("link_elf: symbol %s undefined\n", symname); 825 return ENOENT; 826 } 827 rel++; 828 } 829 } 830 831 /* Perform relocations with addend if there are any: */ 832 rela = ef->pltrela; 833 if (rela) { 834 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 835 while (rela < relalim) { 836 symname = symbol_name(ef, rela->r_info); 837 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) { 838 kprintf("link_elf: symbol %s undefined\n", symname); 839 return ENOENT; 840 } 841 rela++; 842 } 843 } 844 845 return 0; 846 } 847 848 /* 849 * Hash function for symbol table lookup. Don't even think about changing 850 * this. It is specified by the System V ABI. 851 */ 852 static unsigned long 853 elf_hash(const char *name) 854 { 855 const unsigned char *p = (const unsigned char *) name; 856 unsigned long h = 0; 857 unsigned long g; 858 859 while (*p != '\0') { 860 h = (h << 4) + *p++; 861 if ((g = h & 0xf0000000) != 0) 862 h ^= g >> 24; 863 h &= ~g; 864 } 865 return h; 866 } 867 868 int 869 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 870 { 871 elf_file_t ef = lf->priv; 872 unsigned long symnum; 873 const Elf_Sym* symp; 874 const char *strp; 875 unsigned long hash; 876 int i; 877 878 /* If we don't have a hash, bail. */ 879 if (ef->buckets == NULL || ef->nbuckets == 0) { 880 kprintf("link_elf_lookup_symbol: missing symbol hash table\n"); 881 return ENOENT; 882 } 883 884 /* First, search hashed global symbols */ 885 hash = elf_hash(name); 886 symnum = ef->buckets[hash % ef->nbuckets]; 887 888 while (symnum != STN_UNDEF) { 889 if (symnum >= ef->nchains) { 890 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 891 return ENOENT; 892 } 893 894 symp = ef->symtab + symnum; 895 if (symp->st_name == 0) { 896 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 897 return ENOENT; 898 } 899 900 strp = ef->strtab + symp->st_name; 901 902 if (strcmp(name, strp) == 0) { 903 if (symp->st_shndx != SHN_UNDEF || 904 (symp->st_value != 0 && 905 ELF_ST_TYPE(symp->st_info) == STT_FUNC) 906 ) { 907 *sym = (c_linker_sym_t) symp; 908 return 0; 909 } else { 910 return ENOENT; 911 } 912 } 913 914 symnum = ef->chains[symnum]; 915 } 916 917 /* If we have not found it, look at the full table (if loaded) */ 918 if (ef->symtab == ef->ddbsymtab) 919 return ENOENT; 920 921 /* Exhaustive search */ 922 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 923 strp = ef->ddbstrtab + symp->st_name; 924 if (strcmp(name, strp) == 0) { 925 if (symp->st_shndx != SHN_UNDEF || 926 (symp->st_value != 0 && 927 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 928 *sym = (c_linker_sym_t) symp; 929 return 0; 930 } else { 931 return ENOENT; 932 } 933 } 934 } 935 return ENOENT; 936 } 937 938 static int 939 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t *symval) 940 { 941 elf_file_t ef = lf->priv; 942 const Elf_Sym *es = (const Elf_Sym *)sym; 943 944 if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) { 945 symval->name = ef->strtab + es->st_name; 946 symval->value = ef->address + es->st_value; 947 symval->size = es->st_size; 948 return 0; 949 } 950 if (ef->symtab == ef->ddbsymtab) 951 return ENOENT; 952 if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) { 953 symval->name = ef->ddbstrtab + es->st_name; 954 symval->value = ef->address + es->st_value; 955 symval->size = es->st_size; 956 return 0; 957 } 958 return ENOENT; 959 } 960 961 static int 962 link_elf_search_symbol(linker_file_t lf, caddr_t value, 963 c_linker_sym_t *sym, long *diffp) 964 { 965 elf_file_t ef = lf->priv; 966 u_long off = (uintptr_t)(void *)value; 967 u_long diff = off; 968 u_long st_value; 969 const Elf_Sym *es; 970 const Elf_Sym *best = NULL; 971 int i; 972 973 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 974 if (es->st_name == 0) 975 continue; 976 st_value = es->st_value + (uintptr_t)(void *)ef->address; 977 if (off >= st_value) { 978 if (off - st_value < diff) { 979 diff = off - st_value; 980 best = es; 981 if (diff == 0) 982 break; 983 } else if (off - st_value == diff) { 984 best = es; 985 } 986 } 987 } 988 if (best == NULL) 989 *diffp = off; 990 else 991 *diffp = diff; 992 *sym = (c_linker_sym_t) best; 993 994 return 0; 995 } 996 997 /* 998 * Look up a linker set on an ELF system. 999 */ 1000 static int 1001 link_elf_lookup_set(linker_file_t lf, const char *name, 1002 void ***startp, void ***stopp, int *countp) 1003 { 1004 c_linker_sym_t sym; 1005 linker_symval_t symval; 1006 char *setsym; 1007 void **start, **stop; 1008 int len, error = 0, count; 1009 1010 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */ 1011 setsym = kmalloc(len, M_LINKER, M_WAITOK); 1012 1013 /* get address of first entry */ 1014 ksnprintf(setsym, len, "%s%s", "__start_set_", name); 1015 error = link_elf_lookup_symbol(lf, setsym, &sym); 1016 if (error) 1017 goto out; 1018 link_elf_symbol_values(lf, sym, &symval); 1019 if (symval.value == 0) { 1020 error = ESRCH; 1021 goto out; 1022 } 1023 start = (void **)symval.value; 1024 1025 /* get address of last entry */ 1026 ksnprintf(setsym, len, "%s%s", "__stop_set_", name); 1027 error = link_elf_lookup_symbol(lf, setsym, &sym); 1028 if (error) 1029 goto out; 1030 link_elf_symbol_values(lf, sym, &symval); 1031 if (symval.value == 0) { 1032 error = ESRCH; 1033 goto out; 1034 } 1035 stop = (void **)symval.value; 1036 1037 /* and the number of entries */ 1038 count = stop - start; 1039 1040 /* and copy out */ 1041 if (startp) 1042 *startp = start; 1043 if (stopp) 1044 *stopp = stop; 1045 if (countp) 1046 *countp = count; 1047 1048 out: 1049 kfree(setsym, M_LINKER); 1050 return error; 1051 } 1052 1053 /* 1054 * Symbol lookup function that can be used when the symbol index is known (ie 1055 * in relocations). It uses the symbol index instead of doing a fully fledged 1056 * hash table based lookup when such is valid. For example for local symbols. 1057 * This is not only more efficient, it's also more correct. It's not always 1058 * the case that the symbol can be found through the hash table. 1059 */ 1060 static int 1061 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *result) 1062 { 1063 elf_file_t ef = lf->priv; 1064 const Elf_Sym *sym; 1065 const char *symbol; 1066 1067 /* Don't even try to lookup the symbol if the index is bogus. */ 1068 if (symidx >= ef->nchains) 1069 return (ENOENT); 1070 1071 sym = ef->symtab + symidx; 1072 1073 /* 1074 * Don't do a full lookup when the symbol is local. It may even 1075 * fail because it may not be found through the hash table. 1076 */ 1077 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) { 1078 /* Force lookup failure when we have an insanity. */ 1079 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0) 1080 return (ENOENT); 1081 return ((Elf_Addr) ef->address + sym->st_value); 1082 } 1083 /* 1084 * XXX we can avoid doing a hash table based lookup for global 1085 * symbols as well. This however is not always valid, so we'll 1086 * just do it the hard way for now. Performance tweaks can 1087 * always be added. 1088 */ 1089 1090 symbol = ef->strtab + sym->st_name; 1091 1092 /* Force a lookup failure if the symbol name is bogus. */ 1093 if (*symbol == 0) 1094 return (ENOENT); 1095 1096 return (linker_file_lookup_symbol(lf, symbol, deps, (caddr_t *)result)); 1097 } 1098 static void 1099 link_elf_reloc_local(linker_file_t lf) 1100 { 1101 elf_file_t ef = lf->priv; 1102 const Elf_Rel *rellim; 1103 const Elf_Rel *rel; 1104 const Elf_Rela *relalim; 1105 const Elf_Rela *rela; 1106 1107 /* Perform relocations without addend if there are any: */ 1108 if ((rel = ef->rel) != NULL) { 1109 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 1110 while (rel < rellim) { 1111 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, 1112 elf_lookup); 1113 rel++; 1114 } 1115 } 1116 1117 /* Perform relocations with addend if there are any: */ 1118 if ((rela = ef->rela) != NULL) { 1119 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 1120 while (rela < relalim) { 1121 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, 1122 elf_lookup); 1123 rela++; 1124 } 1125 } 1126 } 1127