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(__x86_64__) && 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 = NULL; 153 #ifdef SPARSE_MAPPING 154 ef->object = NULL; 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(__x86_64__) && 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 = NULL; 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 caddr_t mapbase; 417 size_t mapsize; 418 Elf_Addr base_vaddr; 419 Elf_Addr base_vlimit; 420 int error = 0; 421 int resid; 422 elf_file_t ef; 423 linker_file_t lf; 424 char *pathname; 425 Elf_Shdr *shdr; 426 int symtabindex; 427 int symstrindex; 428 int symcnt; 429 int strcnt; 430 431 /* XXX Hack for firmware loading where p == NULL */ 432 if (p == NULL) { 433 p = &proc0; 434 } 435 436 KKASSERT(p != NULL); 437 if (p->p_ucred == NULL) { 438 kprintf("link_elf_load_file: cannot load '%s' from filesystem" 439 " this early\n", filename); 440 return ENOENT; 441 } 442 shdr = NULL; 443 lf = NULL; 444 pathname = linker_search_path(filename); 445 if (pathname == NULL) 446 return ENOENT; 447 448 error = nlookup_init(&nd, pathname, UIO_SYSSPACE, NLC_FOLLOW|NLC_LOCKVP); 449 if (error == 0) 450 error = vn_open(&nd, NULL, FREAD, 0); 451 kfree(pathname, M_LINKER); 452 if (error) { 453 nlookup_done(&nd); 454 return error; 455 } 456 vp = nd.nl_open_vp; 457 nd.nl_open_vp = NULL; 458 nlookup_done(&nd); 459 460 /* 461 * Read the elf header from the file. 462 */ 463 firstpage = kmalloc(PAGE_SIZE, M_LINKER, M_WAITOK); 464 hdr = (Elf_Ehdr *)firstpage; 465 error = vn_rdwr(UIO_READ, vp, firstpage, PAGE_SIZE, 0, 466 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 467 nbytes = PAGE_SIZE - resid; 468 if (error) 469 goto out; 470 471 if (!IS_ELF(*hdr)) { 472 error = ENOEXEC; 473 goto out; 474 } 475 476 if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS 477 || hdr->e_ident[EI_DATA] != ELF_TARG_DATA) { 478 link_elf_error("Unsupported file layout"); 479 error = ENOEXEC; 480 goto out; 481 } 482 if (hdr->e_ident[EI_VERSION] != EV_CURRENT 483 || hdr->e_version != EV_CURRENT) { 484 link_elf_error("Unsupported file version"); 485 error = ENOEXEC; 486 goto out; 487 } 488 if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) { 489 error = ENOSYS; 490 goto out; 491 } 492 if (hdr->e_machine != ELF_TARG_MACH) { 493 link_elf_error("Unsupported machine"); 494 error = ENOEXEC; 495 goto out; 496 } 497 498 /* 499 * We rely on the program header being in the first page. This is 500 * not strictly required by the ABI specification, but it seems to 501 * always true in practice. And, it simplifies things considerably. 502 */ 503 if (!((hdr->e_phentsize == sizeof(Elf_Phdr)) && 504 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) && 505 (hdr->e_phoff + hdr->e_phnum*sizeof(Elf_Phdr) <= nbytes))) 506 link_elf_error("Unreadable program headers"); 507 508 /* 509 * Scan the program header entries, and save key information. 510 * 511 * We rely on there being exactly two load segments, text and data, 512 * in that order. 513 */ 514 phdr = (Elf_Phdr *) (firstpage + hdr->e_phoff); 515 phlimit = phdr + hdr->e_phnum; 516 nsegs = 0; 517 phdyn = NULL; 518 while (phdr < phlimit) { 519 switch (phdr->p_type) { 520 521 case PT_LOAD: 522 if (nsegs == 2) { 523 link_elf_error("Too many sections"); 524 error = ENOEXEC; 525 goto out; 526 } 527 segs[nsegs] = phdr; 528 ++nsegs; 529 break; 530 531 case PT_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_vaddr = trunc_page(segs[0]->p_vaddr); 556 base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); 557 mapsize = base_vlimit - base_vaddr; 558 559 ef = kmalloc(sizeof(struct elf_file), M_LINKER, M_WAITOK | M_ZERO); 560 #ifdef SPARSE_MAPPING 561 ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); 562 if (ef->object == NULL) { 563 kfree(ef, M_LINKER); 564 error = ENOMEM; 565 goto out; 566 } 567 vm_object_hold(ef->object); 568 vm_object_reference_locked(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 vm_object_drop(ef->object); 577 if (error) { 578 vm_object_deallocate(ef->object); 579 kfree(ef, M_LINKER); 580 goto out; 581 } 582 #else 583 ef->address = kmalloc(mapsize, M_LINKER, M_WAITOK); 584 #endif 585 mapbase = ef->address; 586 587 /* 588 * Read the text and data sections and zero the bss. 589 */ 590 for (i = 0; i < 2; i++) { 591 caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; 592 error = vn_rdwr(UIO_READ, vp, 593 segbase, segs[i]->p_filesz, segs[i]->p_offset, 594 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 595 if (error) { 596 #ifdef SPARSE_MAPPING 597 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 598 (vm_offset_t) ef->address 599 + (ef->object->size << PAGE_SHIFT)); 600 vm_object_deallocate(ef->object); 601 #else 602 kfree(ef->address, M_LINKER); 603 #endif 604 kfree(ef, M_LINKER); 605 goto out; 606 } 607 bzero(segbase + segs[i]->p_filesz, 608 segs[i]->p_memsz - segs[i]->p_filesz); 609 610 #ifdef SPARSE_MAPPING 611 /* 612 * Wire down the pages 613 */ 614 vm_map_wire(&kernel_map, 615 (vm_offset_t) segbase, 616 (vm_offset_t) segbase + segs[i]->p_memsz, 617 0); 618 #endif 619 } 620 621 ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); 622 623 lf = linker_make_file(filename, ef, &link_elf_file_ops); 624 if (lf == NULL) { 625 #ifdef SPARSE_MAPPING 626 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 627 (vm_offset_t) ef->address 628 + (ef->object->size << PAGE_SHIFT)); 629 vm_object_deallocate(ef->object); 630 #else 631 kfree(ef->address, M_LINKER); 632 #endif 633 kfree(ef, M_LINKER); 634 error = ENOMEM; 635 goto out; 636 } 637 lf->address = ef->address; 638 lf->size = mapsize; 639 640 error = parse_dynamic(lf); 641 if (error) 642 goto out; 643 link_elf_reloc_local(lf); 644 error = linker_load_dependencies(lf); 645 if (error) 646 goto out; 647 error = relocate_file(lf); 648 if (error) 649 goto out; 650 651 /* Try and load the symbol table if it's present. (you can strip it!) */ 652 nbytes = hdr->e_shnum * hdr->e_shentsize; 653 if (nbytes == 0 || hdr->e_shoff == 0) 654 goto nosyms; 655 shdr = kmalloc(nbytes, M_LINKER, M_WAITOK | M_ZERO); 656 error = vn_rdwr(UIO_READ, vp, 657 (caddr_t)shdr, nbytes, hdr->e_shoff, 658 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 659 if (error) 660 goto out; 661 symtabindex = -1; 662 symstrindex = -1; 663 for (i = 0; i < hdr->e_shnum; i++) { 664 if (shdr[i].sh_type == SHT_SYMTAB) { 665 symtabindex = i; 666 symstrindex = shdr[i].sh_link; 667 } 668 } 669 if (symtabindex < 0 || symstrindex < 0) 670 goto nosyms; 671 672 symcnt = shdr[symtabindex].sh_size; 673 ef->symbase = kmalloc(symcnt, M_LINKER, M_WAITOK); 674 strcnt = shdr[symstrindex].sh_size; 675 ef->strbase = kmalloc(strcnt, M_LINKER, M_WAITOK); 676 error = vn_rdwr(UIO_READ, vp, 677 ef->symbase, symcnt, shdr[symtabindex].sh_offset, 678 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 679 if (error) 680 goto out; 681 error = vn_rdwr(UIO_READ, vp, 682 ef->strbase, strcnt, shdr[symstrindex].sh_offset, 683 UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid); 684 if (error) 685 goto out; 686 687 ef->ddbsymcnt = symcnt / sizeof(Elf_Sym); 688 ef->ddbsymtab = (const Elf_Sym *)ef->symbase; 689 ef->ddbstrcnt = strcnt; 690 ef->ddbstrtab = ef->strbase; 691 692 nosyms: 693 694 *result = lf; 695 696 out: 697 if (error && lf) 698 linker_file_unload(lf); 699 if (shdr) 700 kfree(shdr, M_LINKER); 701 if (firstpage) 702 kfree(firstpage, M_LINKER); 703 vn_unlock(vp); 704 vn_close(vp, FREAD); 705 706 return error; 707 } 708 709 Elf_Addr 710 elf_relocaddr(linker_file_t lf, Elf_Addr x) 711 { 712 #if 0 713 elf_file_t ef; 714 715 ef = lf->priv; 716 if (x >= ef->pcpu_start && x < ef->pcpu_stop) 717 return ((x - ef->pcpu_start) + ef->pcpu_base); 718 #ifdef VIMAGE 719 if (x >= ef->vnet_start && x < ef->vnet_stop) 720 return ((x - ef->vnet_start) + ef->vnet_base); 721 #endif 722 #endif 723 return (x); 724 } 725 726 static void 727 link_elf_unload_file(linker_file_t file) 728 { 729 elf_file_t ef = file->priv; 730 731 if (ef) { 732 #ifdef SPARSE_MAPPING 733 if (ef->object) { 734 vm_map_remove(&kernel_map, (vm_offset_t) ef->address, 735 (vm_offset_t) ef->address 736 + (ef->object->size << PAGE_SHIFT)); 737 vm_object_deallocate(ef->object); 738 } 739 #else 740 if (ef->address) 741 kfree(ef->address, M_LINKER); 742 #endif 743 if (ef->symbase) 744 kfree(ef->symbase, M_LINKER); 745 if (ef->strbase) 746 kfree(ef->strbase, M_LINKER); 747 kfree(ef, M_LINKER); 748 } 749 } 750 751 static void 752 link_elf_unload_module(linker_file_t file) 753 { 754 elf_file_t ef = file->priv; 755 756 if (ef) 757 kfree(ef, M_LINKER); 758 if (file->filename) 759 preload_delete_name(file->filename); 760 } 761 762 static const char * 763 symbol_name(elf_file_t ef, Elf_Size r_info) 764 { 765 const Elf_Sym *ref; 766 767 if (ELF_R_SYM(r_info)) { 768 ref = ef->symtab + ELF_R_SYM(r_info); 769 return ef->strtab + ref->st_name; 770 } else 771 return NULL; 772 } 773 774 static int 775 relocate_file(linker_file_t lf) 776 { 777 elf_file_t ef = lf->priv; 778 const Elf_Rel *rellim; 779 const Elf_Rel *rel; 780 const Elf_Rela *relalim; 781 const Elf_Rela *rela; 782 const char *symname; 783 784 /* Perform relocations without addend if there are any: */ 785 rel = ef->rel; 786 if (rel) { 787 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 788 while (rel < rellim) { 789 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) { 790 symname = symbol_name(ef, rel->r_info); 791 kprintf("link_elf: symbol %s undefined\n", symname); 792 return ENOENT; 793 } 794 rel++; 795 } 796 } 797 798 /* Perform relocations with addend if there are any: */ 799 rela = ef->rela; 800 if (rela) { 801 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 802 while (rela < relalim) { 803 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) { 804 symname = symbol_name(ef, rela->r_info); 805 kprintf("link_elf: symbol %s undefined\n", symname); 806 return ENOENT; 807 } 808 rela++; 809 } 810 } 811 812 /* Perform PLT relocations without addend if there are any: */ 813 rel = ef->pltrel; 814 if (rel) { 815 rellim = (const Elf_Rel *)((const char *)ef->pltrel + ef->pltrelsize); 816 while (rel < rellim) { 817 if (elf_reloc(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, elf_lookup)) { 818 symname = symbol_name(ef, rel->r_info); 819 kprintf("link_elf: symbol %s undefined\n", symname); 820 return ENOENT; 821 } 822 rel++; 823 } 824 } 825 826 /* Perform relocations with addend if there are any: */ 827 rela = ef->pltrela; 828 if (rela) { 829 relalim = (const Elf_Rela *)((const char *)ef->pltrela + ef->pltrelasize); 830 while (rela < relalim) { 831 symname = symbol_name(ef, rela->r_info); 832 if (elf_reloc(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, elf_lookup)) { 833 kprintf("link_elf: symbol %s undefined\n", symname); 834 return ENOENT; 835 } 836 rela++; 837 } 838 } 839 840 return 0; 841 } 842 843 /* 844 * Hash function for symbol table lookup. Don't even think about changing 845 * this. It is specified by the System V ABI. 846 */ 847 static unsigned long 848 elf_hash(const char *name) 849 { 850 const unsigned char *p = (const unsigned char *) name; 851 unsigned long h = 0; 852 unsigned long g; 853 854 while (*p != '\0') { 855 h = (h << 4) + *p++; 856 if ((g = h & 0xf0000000) != 0) 857 h ^= g >> 24; 858 h &= ~g; 859 } 860 return h; 861 } 862 863 int 864 link_elf_lookup_symbol(linker_file_t lf, const char* name, c_linker_sym_t* sym) 865 { 866 elf_file_t ef = lf->priv; 867 unsigned long symnum; 868 const Elf_Sym* symp; 869 const char *strp; 870 unsigned long hash; 871 int i; 872 873 /* If we don't have a hash, bail. */ 874 if (ef->buckets == NULL || ef->nbuckets == 0) { 875 kprintf("link_elf_lookup_symbol: missing symbol hash table\n"); 876 return ENOENT; 877 } 878 879 /* First, search hashed global symbols */ 880 hash = elf_hash(name); 881 symnum = ef->buckets[hash % ef->nbuckets]; 882 883 while (symnum != STN_UNDEF) { 884 if (symnum >= ef->nchains) { 885 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 886 return ENOENT; 887 } 888 889 symp = ef->symtab + symnum; 890 if (symp->st_name == 0) { 891 kprintf("link_elf_lookup_symbol: corrupt symbol table\n"); 892 return ENOENT; 893 } 894 895 strp = ef->strtab + symp->st_name; 896 897 if (strcmp(name, strp) == 0) { 898 if (symp->st_shndx != SHN_UNDEF || 899 (symp->st_value != 0 && 900 ELF_ST_TYPE(symp->st_info) == STT_FUNC) 901 ) { 902 *sym = (c_linker_sym_t) symp; 903 return 0; 904 } else { 905 return ENOENT; 906 } 907 } 908 909 symnum = ef->chains[symnum]; 910 } 911 912 /* If we have not found it, look at the full table (if loaded) */ 913 if (ef->symtab == ef->ddbsymtab) 914 return ENOENT; 915 916 /* Exhaustive search */ 917 for (i = 0, symp = ef->ddbsymtab; i < ef->ddbsymcnt; i++, symp++) { 918 strp = ef->ddbstrtab + symp->st_name; 919 if (strcmp(name, strp) == 0) { 920 if (symp->st_shndx != SHN_UNDEF || 921 (symp->st_value != 0 && 922 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { 923 *sym = (c_linker_sym_t) symp; 924 return 0; 925 } else { 926 return ENOENT; 927 } 928 } 929 } 930 return ENOENT; 931 } 932 933 static int 934 link_elf_symbol_values(linker_file_t lf, c_linker_sym_t sym, linker_symval_t *symval) 935 { 936 elf_file_t ef = lf->priv; 937 const Elf_Sym *es = (const Elf_Sym *)sym; 938 939 if (es >= ef->symtab && ((es - ef->symtab) < ef->nchains)) { 940 symval->name = ef->strtab + es->st_name; 941 symval->value = ef->address + es->st_value; 942 symval->size = es->st_size; 943 return 0; 944 } 945 if (ef->symtab == ef->ddbsymtab) 946 return ENOENT; 947 if (es >= ef->ddbsymtab && ((es - ef->ddbsymtab) < ef->ddbsymcnt)) { 948 symval->name = ef->ddbstrtab + es->st_name; 949 symval->value = ef->address + es->st_value; 950 symval->size = es->st_size; 951 return 0; 952 } 953 return ENOENT; 954 } 955 956 static int 957 link_elf_search_symbol(linker_file_t lf, caddr_t value, 958 c_linker_sym_t *sym, long *diffp) 959 { 960 elf_file_t ef = lf->priv; 961 u_long off = (uintptr_t)(void *)value; 962 u_long diff = off; 963 u_long st_value; 964 const Elf_Sym *es; 965 const Elf_Sym *best = NULL; 966 int i; 967 968 for (i = 0, es = ef->ddbsymtab; i < ef->ddbsymcnt; i++, es++) { 969 if (es->st_name == 0) 970 continue; 971 st_value = es->st_value + (uintptr_t)(void *)ef->address; 972 if (off >= st_value) { 973 if (off - st_value < diff) { 974 diff = off - st_value; 975 best = es; 976 if (diff == 0) 977 break; 978 } else if (off - st_value == diff) { 979 best = es; 980 } 981 } 982 } 983 if (best == NULL) 984 *diffp = off; 985 else 986 *diffp = diff; 987 *sym = (c_linker_sym_t) best; 988 989 return 0; 990 } 991 992 /* 993 * Look up a linker set on an ELF system. 994 */ 995 static int 996 link_elf_lookup_set(linker_file_t lf, const char *name, 997 void ***startp, void ***stopp, int *countp) 998 { 999 c_linker_sym_t sym; 1000 linker_symval_t symval; 1001 char *setsym; 1002 void **start, **stop; 1003 int len, error = 0, count; 1004 1005 len = strlen(name) + sizeof("__start_set_"); /* sizeof includes \0 */ 1006 setsym = kmalloc(len, M_LINKER, M_WAITOK); 1007 1008 /* get address of first entry */ 1009 ksnprintf(setsym, len, "%s%s", "__start_set_", name); 1010 error = link_elf_lookup_symbol(lf, setsym, &sym); 1011 if (error) 1012 goto out; 1013 link_elf_symbol_values(lf, sym, &symval); 1014 if (symval.value == NULL) { 1015 error = ESRCH; 1016 goto out; 1017 } 1018 start = (void **)symval.value; 1019 1020 /* get address of last entry */ 1021 ksnprintf(setsym, len, "%s%s", "__stop_set_", name); 1022 error = link_elf_lookup_symbol(lf, setsym, &sym); 1023 if (error) 1024 goto out; 1025 link_elf_symbol_values(lf, sym, &symval); 1026 if (symval.value == NULL) { 1027 error = ESRCH; 1028 goto out; 1029 } 1030 stop = (void **)symval.value; 1031 1032 /* and the number of entries */ 1033 count = stop - start; 1034 1035 /* and copy out */ 1036 if (startp) 1037 *startp = start; 1038 if (stopp) 1039 *stopp = stop; 1040 if (countp) 1041 *countp = count; 1042 1043 out: 1044 kfree(setsym, M_LINKER); 1045 return error; 1046 } 1047 1048 /* 1049 * Symbol lookup function that can be used when the symbol index is known (ie 1050 * in relocations). It uses the symbol index instead of doing a fully fledged 1051 * hash table based lookup when such is valid. For example for local symbols. 1052 * This is not only more efficient, it's also more correct. It's not always 1053 * the case that the symbol can be found through the hash table. 1054 */ 1055 static int 1056 elf_lookup(linker_file_t lf, Elf_Size symidx, int deps, Elf_Addr *result) 1057 { 1058 elf_file_t ef = lf->priv; 1059 const Elf_Sym *sym; 1060 const char *symbol; 1061 1062 /* Don't even try to lookup the symbol if the index is bogus. */ 1063 if (symidx >= ef->nchains) 1064 return (ENOENT); 1065 1066 sym = ef->symtab + symidx; 1067 1068 /* 1069 * Don't do a full lookup when the symbol is local. It may even 1070 * fail because it may not be found through the hash table. 1071 */ 1072 if (ELF_ST_BIND(sym->st_info) == STB_LOCAL) { 1073 /* Force lookup failure when we have an insanity. */ 1074 if (sym->st_shndx == SHN_UNDEF || sym->st_value == 0) 1075 return (ENOENT); 1076 return ((Elf_Addr) ef->address + sym->st_value); 1077 } 1078 /* 1079 * XXX we can avoid doing a hash table based lookup for global 1080 * symbols as well. This however is not always valid, so we'll 1081 * just do it the hard way for now. Performance tweaks can 1082 * always be added. 1083 */ 1084 1085 symbol = ef->strtab + sym->st_name; 1086 1087 /* Force a lookup failure if the symbol name is bogus. */ 1088 if (*symbol == 0) 1089 return (ENOENT); 1090 1091 return (linker_file_lookup_symbol(lf, symbol, deps, (caddr_t *)result)); 1092 } 1093 static void 1094 link_elf_reloc_local(linker_file_t lf) 1095 { 1096 elf_file_t ef = lf->priv; 1097 const Elf_Rel *rellim; 1098 const Elf_Rel *rel; 1099 const Elf_Rela *relalim; 1100 const Elf_Rela *rela; 1101 1102 /* Perform relocations without addend if there are any: */ 1103 if ((rel = ef->rel) != NULL) { 1104 rellim = (const Elf_Rel *)((const char *)ef->rel + ef->relsize); 1105 while (rel < rellim) { 1106 elf_reloc_local(lf, (Elf_Addr)ef->address, rel, ELF_RELOC_REL, 1107 elf_lookup); 1108 rel++; 1109 } 1110 } 1111 1112 /* Perform relocations with addend if there are any: */ 1113 if ((rela = ef->rela) != NULL) { 1114 relalim = (const Elf_Rela *)((const char *)ef->rela + ef->relasize); 1115 while (rela < relalim) { 1116 elf_reloc_local(lf, (Elf_Addr)ef->address, rela, ELF_RELOC_RELA, 1117 elf_lookup); 1118 rela++; 1119 } 1120 } 1121 } 1122