1 /* Postprocess module symbol versions 2 * 3 * Copyright 2003 Kai Germaschewski 4 * Copyright 2002-2004 Rusty Russell, IBM Corporation 5 * 6 * Based in part on module-init-tools/depmod.c,file2alias 7 * 8 * This software may be used and distributed according to the terms 9 * of the GNU General Public License, incorporated herein by reference. 10 * 11 * Usage: modpost vmlinux module1.o module2.o ... 12 */ 13 14 #include <ctype.h> 15 #include "modpost.h" 16 17 /* Are we using CONFIG_MODVERSIONS? */ 18 int modversions = 0; 19 /* Warn about undefined symbols? (do so if we have vmlinux) */ 20 int have_vmlinux = 0; 21 /* Is CONFIG_MODULE_SRCVERSION_ALL set? */ 22 static int all_versions = 0; 23 24 void 25 fatal(const char *fmt, ...) 26 { 27 va_list arglist; 28 29 fprintf(stderr, "FATAL: "); 30 31 va_start(arglist, fmt); 32 vfprintf(stderr, fmt, arglist); 33 va_end(arglist); 34 35 exit(1); 36 } 37 38 void 39 warn(const char *fmt, ...) 40 { 41 va_list arglist; 42 43 fprintf(stderr, "WARNING: "); 44 45 va_start(arglist, fmt); 46 vfprintf(stderr, fmt, arglist); 47 va_end(arglist); 48 } 49 50 void *do_nofail(void *ptr, const char *expr) 51 { 52 if (!ptr) { 53 fatal("modpost: Memory allocation failure: %s.\n", expr); 54 } 55 return ptr; 56 } 57 58 /* A list of all modules we processed */ 59 60 static struct module *modules; 61 62 struct module * 63 find_module(char *modname) 64 { 65 struct module *mod; 66 67 for (mod = modules; mod; mod = mod->next) 68 if (strcmp(mod->name, modname) == 0) 69 break; 70 return mod; 71 } 72 73 struct module * 74 new_module(char *modname) 75 { 76 struct module *mod; 77 char *p, *s; 78 79 mod = NOFAIL(malloc(sizeof(*mod))); 80 memset(mod, 0, sizeof(*mod)); 81 p = NOFAIL(strdup(modname)); 82 83 /* strip trailing .o */ 84 if ((s = strrchr(p, '.')) != NULL) 85 if (strcmp(s, ".o") == 0) 86 *s = '\0'; 87 88 /* add to list */ 89 mod->name = p; 90 mod->next = modules; 91 modules = mod; 92 93 return mod; 94 } 95 96 /* A hash of all exported symbols, 97 * struct symbol is also used for lists of unresolved symbols */ 98 99 #define SYMBOL_HASH_SIZE 1024 100 101 struct symbol { 102 struct symbol *next; 103 struct module *module; 104 unsigned int crc; 105 int crc_valid; 106 unsigned int weak:1; 107 char name[0]; 108 }; 109 110 static struct symbol *symbolhash[SYMBOL_HASH_SIZE]; 111 112 /* This is based on the hash agorithm from gdbm, via tdb */ 113 static inline unsigned int tdb_hash(const char *name) 114 { 115 unsigned value; /* Used to compute the hash value. */ 116 unsigned i; /* Used to cycle through random values. */ 117 118 /* Set the initial value from the key size. */ 119 for (value = 0x238F13AF * strlen(name), i=0; name[i]; i++) 120 value = (value + (((unsigned char *)name)[i] << (i*5 % 24))); 121 122 return (1103515243 * value + 12345); 123 } 124 125 /* Allocate a new symbols for use in the hash of exported symbols or 126 * the list of unresolved symbols per module */ 127 128 struct symbol * 129 alloc_symbol(const char *name, unsigned int weak, struct symbol *next) 130 { 131 struct symbol *s = NOFAIL(malloc(sizeof(*s) + strlen(name) + 1)); 132 133 memset(s, 0, sizeof(*s)); 134 strcpy(s->name, name); 135 s->weak = weak; 136 s->next = next; 137 return s; 138 } 139 140 /* For the hash of exported symbols */ 141 142 void 143 new_symbol(const char *name, struct module *module, unsigned int *crc) 144 { 145 unsigned int hash; 146 struct symbol *new; 147 148 hash = tdb_hash(name) % SYMBOL_HASH_SIZE; 149 new = symbolhash[hash] = alloc_symbol(name, 0, symbolhash[hash]); 150 new->module = module; 151 if (crc) { 152 new->crc = *crc; 153 new->crc_valid = 1; 154 } 155 } 156 157 struct symbol * 158 find_symbol(const char *name) 159 { 160 struct symbol *s; 161 162 /* For our purposes, .foo matches foo. PPC64 needs this. */ 163 if (name[0] == '.') 164 name++; 165 166 for (s = symbolhash[tdb_hash(name) % SYMBOL_HASH_SIZE]; s; s=s->next) { 167 if (strcmp(s->name, name) == 0) 168 return s; 169 } 170 return NULL; 171 } 172 173 /* Add an exported symbol - it may have already been added without a 174 * CRC, in this case just update the CRC */ 175 void 176 add_exported_symbol(const char *name, struct module *module, unsigned int *crc) 177 { 178 struct symbol *s = find_symbol(name); 179 180 if (!s) { 181 new_symbol(name, module, crc); 182 return; 183 } 184 if (crc) { 185 s->crc = *crc; 186 s->crc_valid = 1; 187 } 188 } 189 190 void * 191 grab_file(const char *filename, unsigned long *size) 192 { 193 struct stat st; 194 void *map; 195 int fd; 196 197 fd = open(filename, O_RDONLY); 198 if (fd < 0 || fstat(fd, &st) != 0) 199 return NULL; 200 201 *size = st.st_size; 202 map = mmap(NULL, *size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); 203 close(fd); 204 205 if (map == MAP_FAILED) 206 return NULL; 207 return map; 208 } 209 210 /* 211 Return a copy of the next line in a mmap'ed file. 212 spaces in the beginning of the line is trimmed away. 213 Return a pointer to a static buffer. 214 */ 215 char* 216 get_next_line(unsigned long *pos, void *file, unsigned long size) 217 { 218 static char line[4096]; 219 int skip = 1; 220 size_t len = 0; 221 signed char *p = (signed char *)file + *pos; 222 char *s = line; 223 224 for (; *pos < size ; (*pos)++) 225 { 226 if (skip && isspace(*p)) { 227 p++; 228 continue; 229 } 230 skip = 0; 231 if (*p != '\n' && (*pos < size)) { 232 len++; 233 *s++ = *p++; 234 if (len > 4095) 235 break; /* Too long, stop */ 236 } else { 237 /* End of string */ 238 *s = '\0'; 239 return line; 240 } 241 } 242 /* End of buffer */ 243 return NULL; 244 } 245 246 void 247 release_file(void *file, unsigned long size) 248 { 249 munmap(file, size); 250 } 251 252 void 253 parse_elf(struct elf_info *info, const char *filename) 254 { 255 unsigned int i; 256 Elf_Ehdr *hdr = info->hdr; 257 Elf_Shdr *sechdrs; 258 Elf_Sym *sym; 259 260 hdr = grab_file(filename, &info->size); 261 if (!hdr) { 262 perror(filename); 263 abort(); 264 } 265 info->hdr = hdr; 266 if (info->size < sizeof(*hdr)) 267 goto truncated; 268 269 /* Fix endianness in ELF header */ 270 hdr->e_shoff = TO_NATIVE(hdr->e_shoff); 271 hdr->e_shstrndx = TO_NATIVE(hdr->e_shstrndx); 272 hdr->e_shnum = TO_NATIVE(hdr->e_shnum); 273 hdr->e_machine = TO_NATIVE(hdr->e_machine); 274 sechdrs = (void *)hdr + hdr->e_shoff; 275 info->sechdrs = sechdrs; 276 277 /* Fix endianness in section headers */ 278 for (i = 0; i < hdr->e_shnum; i++) { 279 sechdrs[i].sh_type = TO_NATIVE(sechdrs[i].sh_type); 280 sechdrs[i].sh_offset = TO_NATIVE(sechdrs[i].sh_offset); 281 sechdrs[i].sh_size = TO_NATIVE(sechdrs[i].sh_size); 282 sechdrs[i].sh_link = TO_NATIVE(sechdrs[i].sh_link); 283 sechdrs[i].sh_name = TO_NATIVE(sechdrs[i].sh_name); 284 } 285 /* Find symbol table. */ 286 for (i = 1; i < hdr->e_shnum; i++) { 287 const char *secstrings 288 = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; 289 290 if (sechdrs[i].sh_offset > info->size) 291 goto truncated; 292 if (strcmp(secstrings+sechdrs[i].sh_name, ".modinfo") == 0) { 293 info->modinfo = (void *)hdr + sechdrs[i].sh_offset; 294 info->modinfo_len = sechdrs[i].sh_size; 295 } 296 if (sechdrs[i].sh_type != SHT_SYMTAB) 297 continue; 298 299 info->symtab_start = (void *)hdr + sechdrs[i].sh_offset; 300 info->symtab_stop = (void *)hdr + sechdrs[i].sh_offset 301 + sechdrs[i].sh_size; 302 info->strtab = (void *)hdr + 303 sechdrs[sechdrs[i].sh_link].sh_offset; 304 } 305 if (!info->symtab_start) { 306 fprintf(stderr, "modpost: %s no symtab?\n", filename); 307 abort(); 308 } 309 /* Fix endianness in symbols */ 310 for (sym = info->symtab_start; sym < info->symtab_stop; sym++) { 311 sym->st_shndx = TO_NATIVE(sym->st_shndx); 312 sym->st_name = TO_NATIVE(sym->st_name); 313 sym->st_value = TO_NATIVE(sym->st_value); 314 sym->st_size = TO_NATIVE(sym->st_size); 315 } 316 return; 317 318 truncated: 319 fprintf(stderr, "modpost: %s is truncated.\n", filename); 320 abort(); 321 } 322 323 void 324 parse_elf_finish(struct elf_info *info) 325 { 326 release_file(info->hdr, info->size); 327 } 328 329 #define CRC_PFX MODULE_SYMBOL_PREFIX "__crc_" 330 #define KSYMTAB_PFX MODULE_SYMBOL_PREFIX "__ksymtab_" 331 332 void 333 handle_modversions(struct module *mod, struct elf_info *info, 334 Elf_Sym *sym, const char *symname) 335 { 336 unsigned int crc; 337 338 switch (sym->st_shndx) { 339 case SHN_COMMON: 340 fprintf(stderr, "*** Warning: \"%s\" [%s] is COMMON symbol\n", 341 symname, mod->name); 342 break; 343 case SHN_ABS: 344 /* CRC'd symbol */ 345 if (memcmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) { 346 crc = (unsigned int) sym->st_value; 347 add_exported_symbol(symname + strlen(CRC_PFX), 348 mod, &crc); 349 } 350 break; 351 case SHN_UNDEF: 352 /* undefined symbol */ 353 if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL && 354 ELF_ST_BIND(sym->st_info) != STB_WEAK) 355 break; 356 /* ignore global offset table */ 357 if (strcmp(symname, "_GLOBAL_OFFSET_TABLE_") == 0) 358 break; 359 /* ignore __this_module, it will be resolved shortly */ 360 if (strcmp(symname, MODULE_SYMBOL_PREFIX "__this_module") == 0) 361 break; 362 #ifdef STT_REGISTER 363 if (info->hdr->e_machine == EM_SPARC || 364 info->hdr->e_machine == EM_SPARCV9) { 365 /* Ignore register directives. */ 366 if (ELF_ST_TYPE(sym->st_info) == STT_REGISTER) 367 break; 368 } 369 #endif 370 371 if (memcmp(symname, MODULE_SYMBOL_PREFIX, 372 strlen(MODULE_SYMBOL_PREFIX)) == 0) 373 mod->unres = alloc_symbol(symname + 374 strlen(MODULE_SYMBOL_PREFIX), 375 ELF_ST_BIND(sym->st_info) == STB_WEAK, 376 mod->unres); 377 break; 378 default: 379 /* All exported symbols */ 380 if (memcmp(symname, KSYMTAB_PFX, strlen(KSYMTAB_PFX)) == 0) { 381 add_exported_symbol(symname + strlen(KSYMTAB_PFX), 382 mod, NULL); 383 } 384 if (strcmp(symname, MODULE_SYMBOL_PREFIX "init_module") == 0) 385 mod->has_init = 1; 386 if (strcmp(symname, MODULE_SYMBOL_PREFIX "cleanup_module") == 0) 387 mod->has_cleanup = 1; 388 break; 389 } 390 } 391 392 int 393 is_vmlinux(const char *modname) 394 { 395 const char *myname; 396 397 if ((myname = strrchr(modname, '/'))) 398 myname++; 399 else 400 myname = modname; 401 402 return strcmp(myname, "vmlinux") == 0; 403 } 404 405 /* Parse tag=value strings from .modinfo section */ 406 static char *next_string(char *string, unsigned long *secsize) 407 { 408 /* Skip non-zero chars */ 409 while (string[0]) { 410 string++; 411 if ((*secsize)-- <= 1) 412 return NULL; 413 } 414 415 /* Skip any zero padding. */ 416 while (!string[0]) { 417 string++; 418 if ((*secsize)-- <= 1) 419 return NULL; 420 } 421 return string; 422 } 423 424 static char *get_modinfo(void *modinfo, unsigned long modinfo_len, 425 const char *tag) 426 { 427 char *p; 428 unsigned int taglen = strlen(tag); 429 unsigned long size = modinfo_len; 430 431 for (p = modinfo; p; p = next_string(p, &size)) { 432 if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=') 433 return p + taglen + 1; 434 } 435 return NULL; 436 } 437 438 void 439 read_symbols(char *modname) 440 { 441 const char *symname; 442 char *version; 443 struct module *mod; 444 struct elf_info info = { }; 445 Elf_Sym *sym; 446 447 parse_elf(&info, modname); 448 449 mod = new_module(modname); 450 451 /* When there's no vmlinux, don't print warnings about 452 * unresolved symbols (since there'll be too many ;) */ 453 if (is_vmlinux(modname)) { 454 unsigned int fake_crc = 0; 455 have_vmlinux = 1; 456 add_exported_symbol("struct_module", mod, &fake_crc); 457 mod->skip = 1; 458 } 459 460 for (sym = info.symtab_start; sym < info.symtab_stop; sym++) { 461 symname = info.strtab + sym->st_name; 462 463 handle_modversions(mod, &info, sym, symname); 464 handle_moddevtable(mod, &info, sym, symname); 465 } 466 467 version = get_modinfo(info.modinfo, info.modinfo_len, "version"); 468 if (version) 469 maybe_frob_rcs_version(modname, version, info.modinfo, 470 version - (char *)info.hdr); 471 if (version || (all_versions && !is_vmlinux(modname))) 472 get_src_version(modname, mod->srcversion, 473 sizeof(mod->srcversion)-1); 474 475 parse_elf_finish(&info); 476 477 /* Our trick to get versioning for struct_module - it's 478 * never passed as an argument to an exported function, so 479 * the automatic versioning doesn't pick it up, but it's really 480 * important anyhow */ 481 if (modversions) 482 mod->unres = alloc_symbol("struct_module", 0, mod->unres); 483 } 484 485 #define SZ 500 486 487 /* We first write the generated file into memory using the 488 * following helper, then compare to the file on disk and 489 * only update the later if anything changed */ 490 491 void __attribute__((format(printf, 2, 3))) 492 buf_printf(struct buffer *buf, const char *fmt, ...) 493 { 494 char tmp[SZ]; 495 int len; 496 va_list ap; 497 498 va_start(ap, fmt); 499 len = vsnprintf(tmp, SZ, fmt, ap); 500 if (buf->size - buf->pos < len + 1) { 501 buf->size += 128; 502 buf->p = realloc(buf->p, buf->size); 503 } 504 strncpy(buf->p + buf->pos, tmp, len + 1); 505 buf->pos += len; 506 va_end(ap); 507 } 508 509 void 510 buf_write(struct buffer *buf, const char *s, int len) 511 { 512 if (buf->size - buf->pos < len) { 513 buf->size += len; 514 buf->p = realloc(buf->p, buf->size); 515 } 516 strncpy(buf->p + buf->pos, s, len); 517 buf->pos += len; 518 } 519 520 /* Header for the generated file */ 521 522 void 523 add_header(struct buffer *b, struct module *mod) 524 { 525 buf_printf(b, "#include <linux/module.h>\n"); 526 buf_printf(b, "#include <linux/vermagic.h>\n"); 527 buf_printf(b, "#include <linux/compiler.h>\n"); 528 buf_printf(b, "\n"); 529 buf_printf(b, "MODULE_INFO(vermagic, VERMAGIC_STRING);\n"); 530 buf_printf(b, "\n"); 531 buf_printf(b, "#undef unix\n"); /* We have a module called "unix" */ 532 buf_printf(b, "struct module __this_module\n"); 533 buf_printf(b, "__attribute__((section(\".gnu.linkonce.this_module\"))) = {\n"); 534 buf_printf(b, " .name = __stringify(KBUILD_MODNAME),\n"); 535 if (mod->has_init) 536 buf_printf(b, " .init = init_module,\n"); 537 if (mod->has_cleanup) 538 buf_printf(b, "#ifdef CONFIG_MODULE_UNLOAD\n" 539 " .exit = cleanup_module,\n" 540 "#endif\n"); 541 buf_printf(b, "};\n"); 542 } 543 544 /* Record CRCs for unresolved symbols */ 545 546 void 547 add_versions(struct buffer *b, struct module *mod) 548 { 549 struct symbol *s, *exp; 550 551 for (s = mod->unres; s; s = s->next) { 552 exp = find_symbol(s->name); 553 if (!exp || exp->module == mod) { 554 if (have_vmlinux && !s->weak) 555 fprintf(stderr, "*** Warning: \"%s\" [%s.ko] " 556 "undefined!\n", s->name, mod->name); 557 continue; 558 } 559 s->module = exp->module; 560 s->crc_valid = exp->crc_valid; 561 s->crc = exp->crc; 562 } 563 564 if (!modversions) 565 return; 566 567 buf_printf(b, "\n"); 568 buf_printf(b, "static const struct modversion_info ____versions[]\n"); 569 buf_printf(b, "__attribute_used__\n"); 570 buf_printf(b, "__attribute__((section(\"__versions\"))) = {\n"); 571 572 for (s = mod->unres; s; s = s->next) { 573 if (!s->module) { 574 continue; 575 } 576 if (!s->crc_valid) { 577 fprintf(stderr, "*** Warning: \"%s\" [%s.ko] " 578 "has no CRC!\n", 579 s->name, mod->name); 580 continue; 581 } 582 buf_printf(b, "\t{ %#8x, \"%s\" },\n", s->crc, s->name); 583 } 584 585 buf_printf(b, "};\n"); 586 } 587 588 void 589 add_depends(struct buffer *b, struct module *mod, struct module *modules) 590 { 591 struct symbol *s; 592 struct module *m; 593 int first = 1; 594 595 for (m = modules; m; m = m->next) { 596 m->seen = is_vmlinux(m->name); 597 } 598 599 buf_printf(b, "\n"); 600 buf_printf(b, "static const char __module_depends[]\n"); 601 buf_printf(b, "__attribute_used__\n"); 602 buf_printf(b, "__attribute__((section(\".modinfo\"))) =\n"); 603 buf_printf(b, "\"depends="); 604 for (s = mod->unres; s; s = s->next) { 605 if (!s->module) 606 continue; 607 608 if (s->module->seen) 609 continue; 610 611 s->module->seen = 1; 612 buf_printf(b, "%s%s", first ? "" : ",", 613 strrchr(s->module->name, '/') + 1); 614 first = 0; 615 } 616 buf_printf(b, "\";\n"); 617 } 618 619 void 620 add_srcversion(struct buffer *b, struct module *mod) 621 { 622 if (mod->srcversion[0]) { 623 buf_printf(b, "\n"); 624 buf_printf(b, "MODULE_INFO(srcversion, \"%s\");\n", 625 mod->srcversion); 626 } 627 } 628 629 void 630 write_if_changed(struct buffer *b, const char *fname) 631 { 632 char *tmp; 633 FILE *file; 634 struct stat st; 635 636 file = fopen(fname, "r"); 637 if (!file) 638 goto write; 639 640 if (fstat(fileno(file), &st) < 0) 641 goto close_write; 642 643 if (st.st_size != b->pos) 644 goto close_write; 645 646 tmp = NOFAIL(malloc(b->pos)); 647 if (fread(tmp, 1, b->pos, file) != b->pos) 648 goto free_write; 649 650 if (memcmp(tmp, b->p, b->pos) != 0) 651 goto free_write; 652 653 free(tmp); 654 fclose(file); 655 return; 656 657 free_write: 658 free(tmp); 659 close_write: 660 fclose(file); 661 write: 662 file = fopen(fname, "w"); 663 if (!file) { 664 perror(fname); 665 exit(1); 666 } 667 if (fwrite(b->p, 1, b->pos, file) != b->pos) { 668 perror(fname); 669 exit(1); 670 } 671 fclose(file); 672 } 673 674 void 675 read_dump(const char *fname) 676 { 677 unsigned long size, pos = 0; 678 void *file = grab_file(fname, &size); 679 char *line; 680 681 if (!file) 682 /* No symbol versions, silently ignore */ 683 return; 684 685 while ((line = get_next_line(&pos, file, size))) { 686 char *symname, *modname, *d; 687 unsigned int crc; 688 struct module *mod; 689 690 if (!(symname = strchr(line, '\t'))) 691 goto fail; 692 *symname++ = '\0'; 693 if (!(modname = strchr(symname, '\t'))) 694 goto fail; 695 *modname++ = '\0'; 696 if (strchr(modname, '\t')) 697 goto fail; 698 crc = strtoul(line, &d, 16); 699 if (*symname == '\0' || *modname == '\0' || *d != '\0') 700 goto fail; 701 702 if (!(mod = find_module(modname))) { 703 if (is_vmlinux(modname)) { 704 have_vmlinux = 1; 705 } 706 mod = new_module(NOFAIL(strdup(modname))); 707 mod->skip = 1; 708 } 709 add_exported_symbol(symname, mod, &crc); 710 } 711 return; 712 fail: 713 fatal("parse error in symbol dump file\n"); 714 } 715 716 void 717 write_dump(const char *fname) 718 { 719 struct buffer buf = { }; 720 struct symbol *symbol; 721 int n; 722 723 for (n = 0; n < SYMBOL_HASH_SIZE ; n++) { 724 symbol = symbolhash[n]; 725 while (symbol) { 726 symbol = symbol->next; 727 } 728 } 729 730 for (n = 0; n < SYMBOL_HASH_SIZE ; n++) { 731 symbol = symbolhash[n]; 732 while (symbol) { 733 buf_printf(&buf, "0x%08x\t%s\t%s\n", symbol->crc, 734 symbol->name, symbol->module->name); 735 symbol = symbol->next; 736 } 737 } 738 write_if_changed(&buf, fname); 739 } 740 741 int 742 main(int argc, char **argv) 743 { 744 struct module *mod; 745 struct buffer buf = { }; 746 char fname[SZ]; 747 char *dump_read = NULL, *dump_write = NULL; 748 int opt; 749 750 while ((opt = getopt(argc, argv, "i:mo:a")) != -1) { 751 switch(opt) { 752 case 'i': 753 dump_read = optarg; 754 break; 755 case 'm': 756 modversions = 1; 757 break; 758 case 'o': 759 dump_write = optarg; 760 break; 761 case 'a': 762 all_versions = 1; 763 break; 764 default: 765 exit(1); 766 } 767 } 768 769 if (dump_read) 770 read_dump(dump_read); 771 772 while (optind < argc) { 773 read_symbols(argv[optind++]); 774 } 775 776 for (mod = modules; mod; mod = mod->next) { 777 if (mod->skip) 778 continue; 779 780 buf.pos = 0; 781 782 add_header(&buf, mod); 783 add_versions(&buf, mod); 784 add_depends(&buf, mod, modules); 785 add_moddevtable(&buf, mod); 786 add_srcversion(&buf, mod); 787 788 sprintf(fname, "%s.mod.c", mod->name); 789 write_if_changed(&buf, fname); 790 } 791 792 if (dump_write) 793 write_dump(dump_write); 794 795 return 0; 796 } 797 798