1 /* Postprocess module symbol versions 2 * 3 * Copyright 2003 Kai Germaschewski 4 * Copyright 2002-2004 Rusty Russell, IBM Corporation 5 * Copyright 2006-2008 Sam Ravnborg 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 #define _GNU_SOURCE 15 #include <stdio.h> 16 #include <ctype.h> 17 #include <string.h> 18 #include <limits.h> 19 #include <stdbool.h> 20 #include <errno.h> 21 #include "modpost.h" 22 #include "../../include/linux/license.h" 23 24 /* Are we using CONFIG_MODVERSIONS? */ 25 static int modversions = 0; 26 /* Warn about undefined symbols? (do so if we have vmlinux) */ 27 static int have_vmlinux = 0; 28 /* Is CONFIG_MODULE_SRCVERSION_ALL set? */ 29 static int all_versions = 0; 30 /* If we are modposting external module set to 1 */ 31 static int external_module = 0; 32 /* Warn about section mismatch in vmlinux if set to 1 */ 33 static int vmlinux_section_warnings = 1; 34 /* Only warn about unresolved symbols */ 35 static int warn_unresolved = 0; 36 /* How a symbol is exported */ 37 static int sec_mismatch_count = 0; 38 static int sec_mismatch_fatal = 0; 39 /* ignore missing files */ 40 static int ignore_missing_files; 41 /* write namespace dependencies */ 42 static int write_namespace_deps; 43 44 enum export { 45 export_plain, export_unused, export_gpl, 46 export_unused_gpl, export_gpl_future, export_unknown 47 }; 48 49 /* In kernel, this size is defined in linux/module.h; 50 * here we use Elf_Addr instead of long for covering cross-compile 51 */ 52 53 #define MODULE_NAME_LEN (64 - sizeof(Elf_Addr)) 54 55 #define PRINTF __attribute__ ((format (printf, 1, 2))) 56 57 PRINTF void fatal(const char *fmt, ...) 58 { 59 va_list arglist; 60 61 fprintf(stderr, "FATAL: "); 62 63 va_start(arglist, fmt); 64 vfprintf(stderr, fmt, arglist); 65 va_end(arglist); 66 67 exit(1); 68 } 69 70 PRINTF void warn(const char *fmt, ...) 71 { 72 va_list arglist; 73 74 fprintf(stderr, "WARNING: "); 75 76 va_start(arglist, fmt); 77 vfprintf(stderr, fmt, arglist); 78 va_end(arglist); 79 } 80 81 PRINTF void merror(const char *fmt, ...) 82 { 83 va_list arglist; 84 85 fprintf(stderr, "ERROR: "); 86 87 va_start(arglist, fmt); 88 vfprintf(stderr, fmt, arglist); 89 va_end(arglist); 90 } 91 92 static inline bool strends(const char *str, const char *postfix) 93 { 94 if (strlen(str) < strlen(postfix)) 95 return false; 96 97 return strcmp(str + strlen(str) - strlen(postfix), postfix) == 0; 98 } 99 100 static int is_vmlinux(const char *modname) 101 { 102 const char *myname; 103 104 myname = strrchr(modname, '/'); 105 if (myname) 106 myname++; 107 else 108 myname = modname; 109 110 return (strcmp(myname, "vmlinux") == 0) || 111 (strcmp(myname, "vmlinux.o") == 0); 112 } 113 114 void *do_nofail(void *ptr, const char *expr) 115 { 116 if (!ptr) 117 fatal("modpost: Memory allocation failure: %s.\n", expr); 118 119 return ptr; 120 } 121 122 /* A list of all modules we processed */ 123 static struct module *modules; 124 125 static struct module *find_module(const char *modname) 126 { 127 struct module *mod; 128 129 for (mod = modules; mod; mod = mod->next) 130 if (strcmp(mod->name, modname) == 0) 131 break; 132 return mod; 133 } 134 135 static struct module *new_module(const char *modname) 136 { 137 struct module *mod; 138 char *p; 139 140 mod = NOFAIL(malloc(sizeof(*mod))); 141 memset(mod, 0, sizeof(*mod)); 142 p = NOFAIL(strdup(modname)); 143 144 /* strip trailing .o */ 145 if (strends(p, ".o")) { 146 p[strlen(p) - 2] = '\0'; 147 mod->is_dot_o = 1; 148 } 149 150 /* add to list */ 151 mod->name = p; 152 mod->gpl_compatible = -1; 153 mod->next = modules; 154 modules = mod; 155 156 return mod; 157 } 158 159 /* A hash of all exported symbols, 160 * struct symbol is also used for lists of unresolved symbols */ 161 162 #define SYMBOL_HASH_SIZE 1024 163 164 struct symbol { 165 struct symbol *next; 166 struct module *module; 167 unsigned int crc; 168 int crc_valid; 169 char *namespace; 170 unsigned int weak:1; 171 unsigned int vmlinux:1; /* 1 if symbol is defined in vmlinux */ 172 unsigned int kernel:1; /* 1 if symbol is from kernel 173 * (only for external modules) **/ 174 unsigned int preloaded:1; /* 1 if symbol from Module.symvers, or crc */ 175 unsigned int is_static:1; /* 1 if symbol is not global */ 176 enum export export; /* Type of export */ 177 char name[0]; 178 }; 179 180 static struct symbol *symbolhash[SYMBOL_HASH_SIZE]; 181 182 /* This is based on the hash agorithm from gdbm, via tdb */ 183 static inline unsigned int tdb_hash(const char *name) 184 { 185 unsigned value; /* Used to compute the hash value. */ 186 unsigned i; /* Used to cycle through random values. */ 187 188 /* Set the initial value from the key size. */ 189 for (value = 0x238F13AF * strlen(name), i = 0; name[i]; i++) 190 value = (value + (((unsigned char *)name)[i] << (i*5 % 24))); 191 192 return (1103515243 * value + 12345); 193 } 194 195 /** 196 * Allocate a new symbols for use in the hash of exported symbols or 197 * the list of unresolved symbols per module 198 **/ 199 static struct symbol *alloc_symbol(const char *name, unsigned int weak, 200 struct symbol *next) 201 { 202 struct symbol *s = NOFAIL(malloc(sizeof(*s) + strlen(name) + 1)); 203 204 memset(s, 0, sizeof(*s)); 205 strcpy(s->name, name); 206 s->weak = weak; 207 s->next = next; 208 s->is_static = 1; 209 return s; 210 } 211 212 /* For the hash of exported symbols */ 213 static struct symbol *new_symbol(const char *name, struct module *module, 214 enum export export) 215 { 216 unsigned int hash; 217 struct symbol *new; 218 219 hash = tdb_hash(name) % SYMBOL_HASH_SIZE; 220 new = symbolhash[hash] = alloc_symbol(name, 0, symbolhash[hash]); 221 new->module = module; 222 new->export = export; 223 return new; 224 } 225 226 static struct symbol *find_symbol(const char *name) 227 { 228 struct symbol *s; 229 230 /* For our purposes, .foo matches foo. PPC64 needs this. */ 231 if (name[0] == '.') 232 name++; 233 234 for (s = symbolhash[tdb_hash(name) % SYMBOL_HASH_SIZE]; s; s = s->next) { 235 if (strcmp(s->name, name) == 0) 236 return s; 237 } 238 return NULL; 239 } 240 241 static bool contains_namespace(struct namespace_list *list, 242 const char *namespace) 243 { 244 struct namespace_list *ns_entry; 245 246 for (ns_entry = list; ns_entry != NULL; ns_entry = ns_entry->next) 247 if (strcmp(ns_entry->namespace, namespace) == 0) 248 return true; 249 250 return false; 251 } 252 253 static void add_namespace(struct namespace_list **list, const char *namespace) 254 { 255 struct namespace_list *ns_entry; 256 257 if (!contains_namespace(*list, namespace)) { 258 ns_entry = NOFAIL(malloc(sizeof(struct namespace_list) + 259 strlen(namespace) + 1)); 260 strcpy(ns_entry->namespace, namespace); 261 ns_entry->next = *list; 262 *list = ns_entry; 263 } 264 } 265 266 static bool module_imports_namespace(struct module *module, 267 const char *namespace) 268 { 269 return contains_namespace(module->imported_namespaces, namespace); 270 } 271 272 static const struct { 273 const char *str; 274 enum export export; 275 } export_list[] = { 276 { .str = "EXPORT_SYMBOL", .export = export_plain }, 277 { .str = "EXPORT_UNUSED_SYMBOL", .export = export_unused }, 278 { .str = "EXPORT_SYMBOL_GPL", .export = export_gpl }, 279 { .str = "EXPORT_UNUSED_SYMBOL_GPL", .export = export_unused_gpl }, 280 { .str = "EXPORT_SYMBOL_GPL_FUTURE", .export = export_gpl_future }, 281 { .str = "(unknown)", .export = export_unknown }, 282 }; 283 284 285 static const char *export_str(enum export ex) 286 { 287 return export_list[ex].str; 288 } 289 290 static enum export export_no(const char *s) 291 { 292 int i; 293 294 if (!s) 295 return export_unknown; 296 for (i = 0; export_list[i].export != export_unknown; i++) { 297 if (strcmp(export_list[i].str, s) == 0) 298 return export_list[i].export; 299 } 300 return export_unknown; 301 } 302 303 static const char *sech_name(struct elf_info *elf, Elf_Shdr *sechdr) 304 { 305 return (void *)elf->hdr + 306 elf->sechdrs[elf->secindex_strings].sh_offset + 307 sechdr->sh_name; 308 } 309 310 static const char *sec_name(struct elf_info *elf, int secindex) 311 { 312 return sech_name(elf, &elf->sechdrs[secindex]); 313 } 314 315 #define strstarts(str, prefix) (strncmp(str, prefix, strlen(prefix)) == 0) 316 317 static enum export export_from_secname(struct elf_info *elf, unsigned int sec) 318 { 319 const char *secname = sec_name(elf, sec); 320 321 if (strstarts(secname, "___ksymtab+")) 322 return export_plain; 323 else if (strstarts(secname, "___ksymtab_unused+")) 324 return export_unused; 325 else if (strstarts(secname, "___ksymtab_gpl+")) 326 return export_gpl; 327 else if (strstarts(secname, "___ksymtab_unused_gpl+")) 328 return export_unused_gpl; 329 else if (strstarts(secname, "___ksymtab_gpl_future+")) 330 return export_gpl_future; 331 else 332 return export_unknown; 333 } 334 335 static enum export export_from_sec(struct elf_info *elf, unsigned int sec) 336 { 337 if (sec == elf->export_sec) 338 return export_plain; 339 else if (sec == elf->export_unused_sec) 340 return export_unused; 341 else if (sec == elf->export_gpl_sec) 342 return export_gpl; 343 else if (sec == elf->export_unused_gpl_sec) 344 return export_unused_gpl; 345 else if (sec == elf->export_gpl_future_sec) 346 return export_gpl_future; 347 else 348 return export_unknown; 349 } 350 351 static char *sym_extract_namespace(const char **symname) 352 { 353 char *namespace = NULL; 354 char *ns_separator; 355 356 ns_separator = strchr(*symname, '.'); 357 if (ns_separator) { 358 namespace = NOFAIL(strndup(*symname, ns_separator - *symname)); 359 *symname = ns_separator + 1; 360 } 361 362 return namespace; 363 } 364 365 /** 366 * Add an exported symbol - it may have already been added without a 367 * CRC, in this case just update the CRC 368 **/ 369 static struct symbol *sym_add_exported(const char *name, const char *namespace, 370 struct module *mod, enum export export) 371 { 372 struct symbol *s = find_symbol(name); 373 374 if (!s) { 375 s = new_symbol(name, mod, export); 376 } else { 377 if (!s->preloaded) { 378 warn("%s: '%s' exported twice. Previous export was in %s%s\n", 379 mod->name, name, s->module->name, 380 is_vmlinux(s->module->name) ? "" : ".ko"); 381 } else { 382 /* In case Module.symvers was out of date */ 383 s->module = mod; 384 } 385 } 386 free(s->namespace); 387 s->namespace = namespace ? strdup(namespace) : NULL; 388 s->preloaded = 0; 389 s->vmlinux = is_vmlinux(mod->name); 390 s->kernel = 0; 391 s->export = export; 392 return s; 393 } 394 395 static void sym_update_crc(const char *name, struct module *mod, 396 unsigned int crc, enum export export) 397 { 398 struct symbol *s = find_symbol(name); 399 400 if (!s) { 401 s = new_symbol(name, mod, export); 402 /* Don't complain when we find it later. */ 403 s->preloaded = 1; 404 } 405 s->crc = crc; 406 s->crc_valid = 1; 407 } 408 409 void *grab_file(const char *filename, unsigned long *size) 410 { 411 struct stat st; 412 void *map = MAP_FAILED; 413 int fd; 414 415 fd = open(filename, O_RDONLY); 416 if (fd < 0) 417 return NULL; 418 if (fstat(fd, &st)) 419 goto failed; 420 421 *size = st.st_size; 422 map = mmap(NULL, *size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); 423 424 failed: 425 close(fd); 426 if (map == MAP_FAILED) 427 return NULL; 428 return map; 429 } 430 431 /** 432 * Return a copy of the next line in a mmap'ed file. 433 * spaces in the beginning of the line is trimmed away. 434 * Return a pointer to a static buffer. 435 **/ 436 char *get_next_line(unsigned long *pos, void *file, unsigned long size) 437 { 438 static char line[4096]; 439 int skip = 1; 440 size_t len = 0; 441 signed char *p = (signed char *)file + *pos; 442 char *s = line; 443 444 for (; *pos < size ; (*pos)++) { 445 if (skip && isspace(*p)) { 446 p++; 447 continue; 448 } 449 skip = 0; 450 if (*p != '\n' && (*pos < size)) { 451 len++; 452 *s++ = *p++; 453 if (len > 4095) 454 break; /* Too long, stop */ 455 } else { 456 /* End of string */ 457 *s = '\0'; 458 return line; 459 } 460 } 461 /* End of buffer */ 462 return NULL; 463 } 464 465 void release_file(void *file, unsigned long size) 466 { 467 munmap(file, size); 468 } 469 470 static int parse_elf(struct elf_info *info, const char *filename) 471 { 472 unsigned int i; 473 Elf_Ehdr *hdr; 474 Elf_Shdr *sechdrs; 475 Elf_Sym *sym; 476 const char *secstrings; 477 unsigned int symtab_idx = ~0U, symtab_shndx_idx = ~0U; 478 479 hdr = grab_file(filename, &info->size); 480 if (!hdr) { 481 if (ignore_missing_files) { 482 fprintf(stderr, "%s: %s (ignored)\n", filename, 483 strerror(errno)); 484 return 0; 485 } 486 perror(filename); 487 exit(1); 488 } 489 info->hdr = hdr; 490 if (info->size < sizeof(*hdr)) { 491 /* file too small, assume this is an empty .o file */ 492 return 0; 493 } 494 /* Is this a valid ELF file? */ 495 if ((hdr->e_ident[EI_MAG0] != ELFMAG0) || 496 (hdr->e_ident[EI_MAG1] != ELFMAG1) || 497 (hdr->e_ident[EI_MAG2] != ELFMAG2) || 498 (hdr->e_ident[EI_MAG3] != ELFMAG3)) { 499 /* Not an ELF file - silently ignore it */ 500 return 0; 501 } 502 /* Fix endianness in ELF header */ 503 hdr->e_type = TO_NATIVE(hdr->e_type); 504 hdr->e_machine = TO_NATIVE(hdr->e_machine); 505 hdr->e_version = TO_NATIVE(hdr->e_version); 506 hdr->e_entry = TO_NATIVE(hdr->e_entry); 507 hdr->e_phoff = TO_NATIVE(hdr->e_phoff); 508 hdr->e_shoff = TO_NATIVE(hdr->e_shoff); 509 hdr->e_flags = TO_NATIVE(hdr->e_flags); 510 hdr->e_ehsize = TO_NATIVE(hdr->e_ehsize); 511 hdr->e_phentsize = TO_NATIVE(hdr->e_phentsize); 512 hdr->e_phnum = TO_NATIVE(hdr->e_phnum); 513 hdr->e_shentsize = TO_NATIVE(hdr->e_shentsize); 514 hdr->e_shnum = TO_NATIVE(hdr->e_shnum); 515 hdr->e_shstrndx = TO_NATIVE(hdr->e_shstrndx); 516 sechdrs = (void *)hdr + hdr->e_shoff; 517 info->sechdrs = sechdrs; 518 519 /* Check if file offset is correct */ 520 if (hdr->e_shoff > info->size) { 521 fatal("section header offset=%lu in file '%s' is bigger than " 522 "filesize=%lu\n", (unsigned long)hdr->e_shoff, 523 filename, info->size); 524 return 0; 525 } 526 527 if (hdr->e_shnum == SHN_UNDEF) { 528 /* 529 * There are more than 64k sections, 530 * read count from .sh_size. 531 */ 532 info->num_sections = TO_NATIVE(sechdrs[0].sh_size); 533 } 534 else { 535 info->num_sections = hdr->e_shnum; 536 } 537 if (hdr->e_shstrndx == SHN_XINDEX) { 538 info->secindex_strings = TO_NATIVE(sechdrs[0].sh_link); 539 } 540 else { 541 info->secindex_strings = hdr->e_shstrndx; 542 } 543 544 /* Fix endianness in section headers */ 545 for (i = 0; i < info->num_sections; i++) { 546 sechdrs[i].sh_name = TO_NATIVE(sechdrs[i].sh_name); 547 sechdrs[i].sh_type = TO_NATIVE(sechdrs[i].sh_type); 548 sechdrs[i].sh_flags = TO_NATIVE(sechdrs[i].sh_flags); 549 sechdrs[i].sh_addr = TO_NATIVE(sechdrs[i].sh_addr); 550 sechdrs[i].sh_offset = TO_NATIVE(sechdrs[i].sh_offset); 551 sechdrs[i].sh_size = TO_NATIVE(sechdrs[i].sh_size); 552 sechdrs[i].sh_link = TO_NATIVE(sechdrs[i].sh_link); 553 sechdrs[i].sh_info = TO_NATIVE(sechdrs[i].sh_info); 554 sechdrs[i].sh_addralign = TO_NATIVE(sechdrs[i].sh_addralign); 555 sechdrs[i].sh_entsize = TO_NATIVE(sechdrs[i].sh_entsize); 556 } 557 /* Find symbol table. */ 558 secstrings = (void *)hdr + sechdrs[info->secindex_strings].sh_offset; 559 for (i = 1; i < info->num_sections; i++) { 560 const char *secname; 561 int nobits = sechdrs[i].sh_type == SHT_NOBITS; 562 563 if (!nobits && sechdrs[i].sh_offset > info->size) { 564 fatal("%s is truncated. sechdrs[i].sh_offset=%lu > " 565 "sizeof(*hrd)=%zu\n", filename, 566 (unsigned long)sechdrs[i].sh_offset, 567 sizeof(*hdr)); 568 return 0; 569 } 570 secname = secstrings + sechdrs[i].sh_name; 571 if (strcmp(secname, ".modinfo") == 0) { 572 if (nobits) 573 fatal("%s has NOBITS .modinfo\n", filename); 574 info->modinfo = (void *)hdr + sechdrs[i].sh_offset; 575 info->modinfo_len = sechdrs[i].sh_size; 576 } else if (strcmp(secname, "__ksymtab") == 0) 577 info->export_sec = i; 578 else if (strcmp(secname, "__ksymtab_unused") == 0) 579 info->export_unused_sec = i; 580 else if (strcmp(secname, "__ksymtab_gpl") == 0) 581 info->export_gpl_sec = i; 582 else if (strcmp(secname, "__ksymtab_unused_gpl") == 0) 583 info->export_unused_gpl_sec = i; 584 else if (strcmp(secname, "__ksymtab_gpl_future") == 0) 585 info->export_gpl_future_sec = i; 586 587 if (sechdrs[i].sh_type == SHT_SYMTAB) { 588 unsigned int sh_link_idx; 589 symtab_idx = i; 590 info->symtab_start = (void *)hdr + 591 sechdrs[i].sh_offset; 592 info->symtab_stop = (void *)hdr + 593 sechdrs[i].sh_offset + sechdrs[i].sh_size; 594 sh_link_idx = sechdrs[i].sh_link; 595 info->strtab = (void *)hdr + 596 sechdrs[sh_link_idx].sh_offset; 597 } 598 599 /* 32bit section no. table? ("more than 64k sections") */ 600 if (sechdrs[i].sh_type == SHT_SYMTAB_SHNDX) { 601 symtab_shndx_idx = i; 602 info->symtab_shndx_start = (void *)hdr + 603 sechdrs[i].sh_offset; 604 info->symtab_shndx_stop = (void *)hdr + 605 sechdrs[i].sh_offset + sechdrs[i].sh_size; 606 } 607 } 608 if (!info->symtab_start) 609 fatal("%s has no symtab?\n", filename); 610 611 /* Fix endianness in symbols */ 612 for (sym = info->symtab_start; sym < info->symtab_stop; sym++) { 613 sym->st_shndx = TO_NATIVE(sym->st_shndx); 614 sym->st_name = TO_NATIVE(sym->st_name); 615 sym->st_value = TO_NATIVE(sym->st_value); 616 sym->st_size = TO_NATIVE(sym->st_size); 617 } 618 619 if (symtab_shndx_idx != ~0U) { 620 Elf32_Word *p; 621 if (symtab_idx != sechdrs[symtab_shndx_idx].sh_link) 622 fatal("%s: SYMTAB_SHNDX has bad sh_link: %u!=%u\n", 623 filename, sechdrs[symtab_shndx_idx].sh_link, 624 symtab_idx); 625 /* Fix endianness */ 626 for (p = info->symtab_shndx_start; p < info->symtab_shndx_stop; 627 p++) 628 *p = TO_NATIVE(*p); 629 } 630 631 return 1; 632 } 633 634 static void parse_elf_finish(struct elf_info *info) 635 { 636 release_file(info->hdr, info->size); 637 } 638 639 static int ignore_undef_symbol(struct elf_info *info, const char *symname) 640 { 641 /* ignore __this_module, it will be resolved shortly */ 642 if (strcmp(symname, "__this_module") == 0) 643 return 1; 644 /* ignore global offset table */ 645 if (strcmp(symname, "_GLOBAL_OFFSET_TABLE_") == 0) 646 return 1; 647 if (info->hdr->e_machine == EM_PPC) 648 /* Special register function linked on all modules during final link of .ko */ 649 if (strstarts(symname, "_restgpr_") || 650 strstarts(symname, "_savegpr_") || 651 strstarts(symname, "_rest32gpr_") || 652 strstarts(symname, "_save32gpr_") || 653 strstarts(symname, "_restvr_") || 654 strstarts(symname, "_savevr_")) 655 return 1; 656 if (info->hdr->e_machine == EM_PPC64) 657 /* Special register function linked on all modules during final link of .ko */ 658 if (strstarts(symname, "_restgpr0_") || 659 strstarts(symname, "_savegpr0_") || 660 strstarts(symname, "_restvr_") || 661 strstarts(symname, "_savevr_") || 662 strcmp(symname, ".TOC.") == 0) 663 return 1; 664 /* Do not ignore this symbol */ 665 return 0; 666 } 667 668 static void handle_modversions(struct module *mod, struct elf_info *info, 669 Elf_Sym *sym, const char *symname) 670 { 671 unsigned int crc; 672 enum export export; 673 bool is_crc = false; 674 const char *name; 675 char *namespace; 676 677 if ((!is_vmlinux(mod->name) || mod->is_dot_o) && 678 strstarts(symname, "__ksymtab")) 679 export = export_from_secname(info, get_secindex(info, sym)); 680 else 681 export = export_from_sec(info, get_secindex(info, sym)); 682 683 /* CRC'd symbol */ 684 if (strstarts(symname, "__crc_")) { 685 is_crc = true; 686 crc = (unsigned int) sym->st_value; 687 if (sym->st_shndx != SHN_UNDEF && sym->st_shndx != SHN_ABS) { 688 unsigned int *crcp; 689 690 /* symbol points to the CRC in the ELF object */ 691 crcp = (void *)info->hdr + sym->st_value + 692 info->sechdrs[sym->st_shndx].sh_offset - 693 (info->hdr->e_type != ET_REL ? 694 info->sechdrs[sym->st_shndx].sh_addr : 0); 695 crc = TO_NATIVE(*crcp); 696 } 697 sym_update_crc(symname + strlen("__crc_"), mod, crc, 698 export); 699 } 700 701 switch (sym->st_shndx) { 702 case SHN_COMMON: 703 if (strstarts(symname, "__gnu_lto_")) { 704 /* Should warn here, but modpost runs before the linker */ 705 } else 706 warn("\"%s\" [%s] is COMMON symbol\n", symname, mod->name); 707 break; 708 case SHN_UNDEF: 709 /* undefined symbol */ 710 if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL && 711 ELF_ST_BIND(sym->st_info) != STB_WEAK) 712 break; 713 if (ignore_undef_symbol(info, symname)) 714 break; 715 /* cope with newer glibc (2.3.4 or higher) STT_ definition in elf.h */ 716 #if defined(STT_REGISTER) || defined(STT_SPARC_REGISTER) 717 /* add compatibility with older glibc */ 718 #ifndef STT_SPARC_REGISTER 719 #define STT_SPARC_REGISTER STT_REGISTER 720 #endif 721 if (info->hdr->e_machine == EM_SPARC || 722 info->hdr->e_machine == EM_SPARCV9) { 723 /* Ignore register directives. */ 724 if (ELF_ST_TYPE(sym->st_info) == STT_SPARC_REGISTER) 725 break; 726 if (symname[0] == '.') { 727 char *munged = NOFAIL(strdup(symname)); 728 munged[0] = '_'; 729 munged[1] = toupper(munged[1]); 730 symname = munged; 731 } 732 } 733 #endif 734 735 if (is_crc) { 736 const char *e = is_vmlinux(mod->name) ?"":".ko"; 737 warn("EXPORT symbol \"%s\" [%s%s] version generation failed, symbol will not be versioned.\n", 738 symname + strlen("__crc_"), mod->name, e); 739 } 740 mod->unres = alloc_symbol(symname, 741 ELF_ST_BIND(sym->st_info) == STB_WEAK, 742 mod->unres); 743 break; 744 default: 745 /* All exported symbols */ 746 if (strstarts(symname, "__ksymtab_")) { 747 name = symname + strlen("__ksymtab_"); 748 namespace = sym_extract_namespace(&name); 749 sym_add_exported(name, namespace, mod, export); 750 free(namespace); 751 } 752 if (strcmp(symname, "init_module") == 0) 753 mod->has_init = 1; 754 if (strcmp(symname, "cleanup_module") == 0) 755 mod->has_cleanup = 1; 756 break; 757 } 758 } 759 760 /** 761 * Parse tag=value strings from .modinfo section 762 **/ 763 static char *next_string(char *string, unsigned long *secsize) 764 { 765 /* Skip non-zero chars */ 766 while (string[0]) { 767 string++; 768 if ((*secsize)-- <= 1) 769 return NULL; 770 } 771 772 /* Skip any zero padding. */ 773 while (!string[0]) { 774 string++; 775 if ((*secsize)-- <= 1) 776 return NULL; 777 } 778 return string; 779 } 780 781 static char *get_next_modinfo(struct elf_info *info, const char *tag, 782 char *prev) 783 { 784 char *p; 785 unsigned int taglen = strlen(tag); 786 char *modinfo = info->modinfo; 787 unsigned long size = info->modinfo_len; 788 789 if (prev) { 790 size -= prev - modinfo; 791 modinfo = next_string(prev, &size); 792 } 793 794 for (p = modinfo; p; p = next_string(p, &size)) { 795 if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=') 796 return p + taglen + 1; 797 } 798 return NULL; 799 } 800 801 static char *get_modinfo(struct elf_info *info, const char *tag) 802 803 { 804 return get_next_modinfo(info, tag, NULL); 805 } 806 807 /** 808 * Test if string s ends in string sub 809 * return 0 if match 810 **/ 811 static int strrcmp(const char *s, const char *sub) 812 { 813 int slen, sublen; 814 815 if (!s || !sub) 816 return 1; 817 818 slen = strlen(s); 819 sublen = strlen(sub); 820 821 if ((slen == 0) || (sublen == 0)) 822 return 1; 823 824 if (sublen > slen) 825 return 1; 826 827 return memcmp(s + slen - sublen, sub, sublen); 828 } 829 830 static const char *sym_name(struct elf_info *elf, Elf_Sym *sym) 831 { 832 if (sym) 833 return elf->strtab + sym->st_name; 834 else 835 return "(unknown)"; 836 } 837 838 /* The pattern is an array of simple patterns. 839 * "foo" will match an exact string equal to "foo" 840 * "*foo" will match a string that ends with "foo" 841 * "foo*" will match a string that begins with "foo" 842 * "*foo*" will match a string that contains "foo" 843 */ 844 static int match(const char *sym, const char * const pat[]) 845 { 846 const char *p; 847 while (*pat) { 848 p = *pat++; 849 const char *endp = p + strlen(p) - 1; 850 851 /* "*foo*" */ 852 if (*p == '*' && *endp == '*') { 853 char *bare = NOFAIL(strndup(p + 1, strlen(p) - 2)); 854 char *here = strstr(sym, bare); 855 856 free(bare); 857 if (here != NULL) 858 return 1; 859 } 860 /* "*foo" */ 861 else if (*p == '*') { 862 if (strrcmp(sym, p + 1) == 0) 863 return 1; 864 } 865 /* "foo*" */ 866 else if (*endp == '*') { 867 if (strncmp(sym, p, strlen(p) - 1) == 0) 868 return 1; 869 } 870 /* no wildcards */ 871 else { 872 if (strcmp(p, sym) == 0) 873 return 1; 874 } 875 } 876 /* no match */ 877 return 0; 878 } 879 880 /* sections that we do not want to do full section mismatch check on */ 881 static const char *const section_white_list[] = 882 { 883 ".comment*", 884 ".debug*", 885 ".cranges", /* sh64 */ 886 ".zdebug*", /* Compressed debug sections. */ 887 ".GCC.command.line", /* record-gcc-switches */ 888 ".mdebug*", /* alpha, score, mips etc. */ 889 ".pdr", /* alpha, score, mips etc. */ 890 ".stab*", 891 ".note*", 892 ".got*", 893 ".toc*", 894 ".xt.prop", /* xtensa */ 895 ".xt.lit", /* xtensa */ 896 ".arcextmap*", /* arc */ 897 ".gnu.linkonce.arcext*", /* arc : modules */ 898 ".cmem*", /* EZchip */ 899 ".fmt_slot*", /* EZchip */ 900 ".gnu.lto*", 901 ".discard.*", 902 NULL 903 }; 904 905 /* 906 * This is used to find sections missing the SHF_ALLOC flag. 907 * The cause of this is often a section specified in assembler 908 * without "ax" / "aw". 909 */ 910 static void check_section(const char *modname, struct elf_info *elf, 911 Elf_Shdr *sechdr) 912 { 913 const char *sec = sech_name(elf, sechdr); 914 915 if (sechdr->sh_type == SHT_PROGBITS && 916 !(sechdr->sh_flags & SHF_ALLOC) && 917 !match(sec, section_white_list)) { 918 warn("%s (%s): unexpected non-allocatable section.\n" 919 "Did you forget to use \"ax\"/\"aw\" in a .S file?\n" 920 "Note that for example <linux/init.h> contains\n" 921 "section definitions for use in .S files.\n\n", 922 modname, sec); 923 } 924 } 925 926 927 928 #define ALL_INIT_DATA_SECTIONS \ 929 ".init.setup", ".init.rodata", ".meminit.rodata", \ 930 ".init.data", ".meminit.data" 931 #define ALL_EXIT_DATA_SECTIONS \ 932 ".exit.data", ".memexit.data" 933 934 #define ALL_INIT_TEXT_SECTIONS \ 935 ".init.text", ".meminit.text" 936 #define ALL_EXIT_TEXT_SECTIONS \ 937 ".exit.text", ".memexit.text" 938 939 #define ALL_PCI_INIT_SECTIONS \ 940 ".pci_fixup_early", ".pci_fixup_header", ".pci_fixup_final", \ 941 ".pci_fixup_enable", ".pci_fixup_resume", \ 942 ".pci_fixup_resume_early", ".pci_fixup_suspend" 943 944 #define ALL_XXXINIT_SECTIONS MEM_INIT_SECTIONS 945 #define ALL_XXXEXIT_SECTIONS MEM_EXIT_SECTIONS 946 947 #define ALL_INIT_SECTIONS INIT_SECTIONS, ALL_XXXINIT_SECTIONS 948 #define ALL_EXIT_SECTIONS EXIT_SECTIONS, ALL_XXXEXIT_SECTIONS 949 950 #define DATA_SECTIONS ".data", ".data.rel" 951 #define TEXT_SECTIONS ".text", ".text.unlikely", ".sched.text", \ 952 ".kprobes.text", ".cpuidle.text" 953 #define OTHER_TEXT_SECTIONS ".ref.text", ".head.text", ".spinlock.text", \ 954 ".fixup", ".entry.text", ".exception.text", ".text.*", \ 955 ".coldtext" 956 957 #define INIT_SECTIONS ".init.*" 958 #define MEM_INIT_SECTIONS ".meminit.*" 959 960 #define EXIT_SECTIONS ".exit.*" 961 #define MEM_EXIT_SECTIONS ".memexit.*" 962 963 #define ALL_TEXT_SECTIONS ALL_INIT_TEXT_SECTIONS, ALL_EXIT_TEXT_SECTIONS, \ 964 TEXT_SECTIONS, OTHER_TEXT_SECTIONS 965 966 /* init data sections */ 967 static const char *const init_data_sections[] = 968 { ALL_INIT_DATA_SECTIONS, NULL }; 969 970 /* all init sections */ 971 static const char *const init_sections[] = { ALL_INIT_SECTIONS, NULL }; 972 973 /* All init and exit sections (code + data) */ 974 static const char *const init_exit_sections[] = 975 {ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS, NULL }; 976 977 /* all text sections */ 978 static const char *const text_sections[] = { ALL_TEXT_SECTIONS, NULL }; 979 980 /* data section */ 981 static const char *const data_sections[] = { DATA_SECTIONS, NULL }; 982 983 984 /* symbols in .data that may refer to init/exit sections */ 985 #define DEFAULT_SYMBOL_WHITE_LIST \ 986 "*driver", \ 987 "*_template", /* scsi uses *_template a lot */ \ 988 "*_timer", /* arm uses ops structures named _timer a lot */ \ 989 "*_sht", /* scsi also used *_sht to some extent */ \ 990 "*_ops", \ 991 "*_probe", \ 992 "*_probe_one", \ 993 "*_console" 994 995 static const char *const head_sections[] = { ".head.text*", NULL }; 996 static const char *const linker_symbols[] = 997 { "__init_begin", "_sinittext", "_einittext", NULL }; 998 static const char *const optim_symbols[] = { "*.constprop.*", NULL }; 999 1000 enum mismatch { 1001 TEXT_TO_ANY_INIT, 1002 DATA_TO_ANY_INIT, 1003 TEXT_TO_ANY_EXIT, 1004 DATA_TO_ANY_EXIT, 1005 XXXINIT_TO_SOME_INIT, 1006 XXXEXIT_TO_SOME_EXIT, 1007 ANY_INIT_TO_ANY_EXIT, 1008 ANY_EXIT_TO_ANY_INIT, 1009 EXPORT_TO_INIT_EXIT, 1010 EXTABLE_TO_NON_TEXT, 1011 }; 1012 1013 /** 1014 * Describe how to match sections on different criterias: 1015 * 1016 * @fromsec: Array of sections to be matched. 1017 * 1018 * @bad_tosec: Relocations applied to a section in @fromsec to a section in 1019 * this array is forbidden (black-list). Can be empty. 1020 * 1021 * @good_tosec: Relocations applied to a section in @fromsec must be 1022 * targetting sections in this array (white-list). Can be empty. 1023 * 1024 * @mismatch: Type of mismatch. 1025 * 1026 * @symbol_white_list: Do not match a relocation to a symbol in this list 1027 * even if it is targetting a section in @bad_to_sec. 1028 * 1029 * @handler: Specific handler to call when a match is found. If NULL, 1030 * default_mismatch_handler() will be called. 1031 * 1032 */ 1033 struct sectioncheck { 1034 const char *fromsec[20]; 1035 const char *bad_tosec[20]; 1036 const char *good_tosec[20]; 1037 enum mismatch mismatch; 1038 const char *symbol_white_list[20]; 1039 void (*handler)(const char *modname, struct elf_info *elf, 1040 const struct sectioncheck* const mismatch, 1041 Elf_Rela *r, Elf_Sym *sym, const char *fromsec); 1042 1043 }; 1044 1045 static void extable_mismatch_handler(const char *modname, struct elf_info *elf, 1046 const struct sectioncheck* const mismatch, 1047 Elf_Rela *r, Elf_Sym *sym, 1048 const char *fromsec); 1049 1050 static const struct sectioncheck sectioncheck[] = { 1051 /* Do not reference init/exit code/data from 1052 * normal code and data 1053 */ 1054 { 1055 .fromsec = { TEXT_SECTIONS, NULL }, 1056 .bad_tosec = { ALL_INIT_SECTIONS, NULL }, 1057 .mismatch = TEXT_TO_ANY_INIT, 1058 .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, 1059 }, 1060 { 1061 .fromsec = { DATA_SECTIONS, NULL }, 1062 .bad_tosec = { ALL_XXXINIT_SECTIONS, NULL }, 1063 .mismatch = DATA_TO_ANY_INIT, 1064 .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, 1065 }, 1066 { 1067 .fromsec = { DATA_SECTIONS, NULL }, 1068 .bad_tosec = { INIT_SECTIONS, NULL }, 1069 .mismatch = DATA_TO_ANY_INIT, 1070 .symbol_white_list = { 1071 "*_template", "*_timer", "*_sht", "*_ops", 1072 "*_probe", "*_probe_one", "*_console", NULL 1073 }, 1074 }, 1075 { 1076 .fromsec = { TEXT_SECTIONS, NULL }, 1077 .bad_tosec = { ALL_EXIT_SECTIONS, NULL }, 1078 .mismatch = TEXT_TO_ANY_EXIT, 1079 .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, 1080 }, 1081 { 1082 .fromsec = { DATA_SECTIONS, NULL }, 1083 .bad_tosec = { ALL_EXIT_SECTIONS, NULL }, 1084 .mismatch = DATA_TO_ANY_EXIT, 1085 .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, 1086 }, 1087 /* Do not reference init code/data from meminit code/data */ 1088 { 1089 .fromsec = { ALL_XXXINIT_SECTIONS, NULL }, 1090 .bad_tosec = { INIT_SECTIONS, NULL }, 1091 .mismatch = XXXINIT_TO_SOME_INIT, 1092 .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, 1093 }, 1094 /* Do not reference exit code/data from memexit code/data */ 1095 { 1096 .fromsec = { ALL_XXXEXIT_SECTIONS, NULL }, 1097 .bad_tosec = { EXIT_SECTIONS, NULL }, 1098 .mismatch = XXXEXIT_TO_SOME_EXIT, 1099 .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, 1100 }, 1101 /* Do not use exit code/data from init code */ 1102 { 1103 .fromsec = { ALL_INIT_SECTIONS, NULL }, 1104 .bad_tosec = { ALL_EXIT_SECTIONS, NULL }, 1105 .mismatch = ANY_INIT_TO_ANY_EXIT, 1106 .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, 1107 }, 1108 /* Do not use init code/data from exit code */ 1109 { 1110 .fromsec = { ALL_EXIT_SECTIONS, NULL }, 1111 .bad_tosec = { ALL_INIT_SECTIONS, NULL }, 1112 .mismatch = ANY_EXIT_TO_ANY_INIT, 1113 .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, 1114 }, 1115 { 1116 .fromsec = { ALL_PCI_INIT_SECTIONS, NULL }, 1117 .bad_tosec = { INIT_SECTIONS, NULL }, 1118 .mismatch = ANY_INIT_TO_ANY_EXIT, 1119 .symbol_white_list = { NULL }, 1120 }, 1121 /* Do not export init/exit functions or data */ 1122 { 1123 .fromsec = { "__ksymtab*", NULL }, 1124 .bad_tosec = { INIT_SECTIONS, EXIT_SECTIONS, NULL }, 1125 .mismatch = EXPORT_TO_INIT_EXIT, 1126 .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, 1127 }, 1128 { 1129 .fromsec = { "__ex_table", NULL }, 1130 /* If you're adding any new black-listed sections in here, consider 1131 * adding a special 'printer' for them in scripts/check_extable. 1132 */ 1133 .bad_tosec = { ".altinstr_replacement", NULL }, 1134 .good_tosec = {ALL_TEXT_SECTIONS , NULL}, 1135 .mismatch = EXTABLE_TO_NON_TEXT, 1136 .handler = extable_mismatch_handler, 1137 } 1138 }; 1139 1140 static const struct sectioncheck *section_mismatch( 1141 const char *fromsec, const char *tosec) 1142 { 1143 int i; 1144 int elems = sizeof(sectioncheck) / sizeof(struct sectioncheck); 1145 const struct sectioncheck *check = §ioncheck[0]; 1146 1147 /* 1148 * The target section could be the SHT_NUL section when we're 1149 * handling relocations to un-resolved symbols, trying to match it 1150 * doesn't make much sense and causes build failures on parisc 1151 * architectures. 1152 */ 1153 if (*tosec == '\0') 1154 return NULL; 1155 1156 for (i = 0; i < elems; i++) { 1157 if (match(fromsec, check->fromsec)) { 1158 if (check->bad_tosec[0] && match(tosec, check->bad_tosec)) 1159 return check; 1160 if (check->good_tosec[0] && !match(tosec, check->good_tosec)) 1161 return check; 1162 } 1163 check++; 1164 } 1165 return NULL; 1166 } 1167 1168 /** 1169 * Whitelist to allow certain references to pass with no warning. 1170 * 1171 * Pattern 1: 1172 * If a module parameter is declared __initdata and permissions=0 1173 * then this is legal despite the warning generated. 1174 * We cannot see value of permissions here, so just ignore 1175 * this pattern. 1176 * The pattern is identified by: 1177 * tosec = .init.data 1178 * fromsec = .data* 1179 * atsym =__param* 1180 * 1181 * Pattern 1a: 1182 * module_param_call() ops can refer to __init set function if permissions=0 1183 * The pattern is identified by: 1184 * tosec = .init.text 1185 * fromsec = .data* 1186 * atsym = __param_ops_* 1187 * 1188 * Pattern 2: 1189 * Many drivers utilise a *driver container with references to 1190 * add, remove, probe functions etc. 1191 * the pattern is identified by: 1192 * tosec = init or exit section 1193 * fromsec = data section 1194 * atsym = *driver, *_template, *_sht, *_ops, *_probe, 1195 * *probe_one, *_console, *_timer 1196 * 1197 * Pattern 3: 1198 * Whitelist all references from .head.text to any init section 1199 * 1200 * Pattern 4: 1201 * Some symbols belong to init section but still it is ok to reference 1202 * these from non-init sections as these symbols don't have any memory 1203 * allocated for them and symbol address and value are same. So even 1204 * if init section is freed, its ok to reference those symbols. 1205 * For ex. symbols marking the init section boundaries. 1206 * This pattern is identified by 1207 * refsymname = __init_begin, _sinittext, _einittext 1208 * 1209 * Pattern 5: 1210 * GCC may optimize static inlines when fed constant arg(s) resulting 1211 * in functions like cpumask_empty() -- generating an associated symbol 1212 * cpumask_empty.constprop.3 that appears in the audit. If the const that 1213 * is passed in comes from __init, like say nmi_ipi_mask, we get a 1214 * meaningless section warning. May need to add isra symbols too... 1215 * This pattern is identified by 1216 * tosec = init section 1217 * fromsec = text section 1218 * refsymname = *.constprop.* 1219 * 1220 * Pattern 6: 1221 * Hide section mismatch warnings for ELF local symbols. The goal 1222 * is to eliminate false positive modpost warnings caused by 1223 * compiler-generated ELF local symbol names such as ".LANCHOR1". 1224 * Autogenerated symbol names bypass modpost's "Pattern 2" 1225 * whitelisting, which relies on pattern-matching against symbol 1226 * names to work. (One situation where gcc can autogenerate ELF 1227 * local symbols is when "-fsection-anchors" is used.) 1228 **/ 1229 static int secref_whitelist(const struct sectioncheck *mismatch, 1230 const char *fromsec, const char *fromsym, 1231 const char *tosec, const char *tosym) 1232 { 1233 /* Check for pattern 1 */ 1234 if (match(tosec, init_data_sections) && 1235 match(fromsec, data_sections) && 1236 strstarts(fromsym, "__param")) 1237 return 0; 1238 1239 /* Check for pattern 1a */ 1240 if (strcmp(tosec, ".init.text") == 0 && 1241 match(fromsec, data_sections) && 1242 strstarts(fromsym, "__param_ops_")) 1243 return 0; 1244 1245 /* Check for pattern 2 */ 1246 if (match(tosec, init_exit_sections) && 1247 match(fromsec, data_sections) && 1248 match(fromsym, mismatch->symbol_white_list)) 1249 return 0; 1250 1251 /* Check for pattern 3 */ 1252 if (match(fromsec, head_sections) && 1253 match(tosec, init_sections)) 1254 return 0; 1255 1256 /* Check for pattern 4 */ 1257 if (match(tosym, linker_symbols)) 1258 return 0; 1259 1260 /* Check for pattern 5 */ 1261 if (match(fromsec, text_sections) && 1262 match(tosec, init_sections) && 1263 match(fromsym, optim_symbols)) 1264 return 0; 1265 1266 /* Check for pattern 6 */ 1267 if (strstarts(fromsym, ".L")) 1268 return 0; 1269 1270 return 1; 1271 } 1272 1273 static inline int is_arm_mapping_symbol(const char *str) 1274 { 1275 return str[0] == '$' && strchr("axtd", str[1]) 1276 && (str[2] == '\0' || str[2] == '.'); 1277 } 1278 1279 /* 1280 * If there's no name there, ignore it; likewise, ignore it if it's 1281 * one of the magic symbols emitted used by current ARM tools. 1282 * 1283 * Otherwise if find_symbols_between() returns those symbols, they'll 1284 * fail the whitelist tests and cause lots of false alarms ... fixable 1285 * only by merging __exit and __init sections into __text, bloating 1286 * the kernel (which is especially evil on embedded platforms). 1287 */ 1288 static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym) 1289 { 1290 const char *name = elf->strtab + sym->st_name; 1291 1292 if (!name || !strlen(name)) 1293 return 0; 1294 return !is_arm_mapping_symbol(name); 1295 } 1296 1297 /** 1298 * Find symbol based on relocation record info. 1299 * In some cases the symbol supplied is a valid symbol so 1300 * return refsym. If st_name != 0 we assume this is a valid symbol. 1301 * In other cases the symbol needs to be looked up in the symbol table 1302 * based on section and address. 1303 * **/ 1304 static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf64_Sword addr, 1305 Elf_Sym *relsym) 1306 { 1307 Elf_Sym *sym; 1308 Elf_Sym *near = NULL; 1309 Elf64_Sword distance = 20; 1310 Elf64_Sword d; 1311 unsigned int relsym_secindex; 1312 1313 if (relsym->st_name != 0) 1314 return relsym; 1315 1316 relsym_secindex = get_secindex(elf, relsym); 1317 for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) { 1318 if (get_secindex(elf, sym) != relsym_secindex) 1319 continue; 1320 if (ELF_ST_TYPE(sym->st_info) == STT_SECTION) 1321 continue; 1322 if (!is_valid_name(elf, sym)) 1323 continue; 1324 if (sym->st_value == addr) 1325 return sym; 1326 /* Find a symbol nearby - addr are maybe negative */ 1327 d = sym->st_value - addr; 1328 if (d < 0) 1329 d = addr - sym->st_value; 1330 if (d < distance) { 1331 distance = d; 1332 near = sym; 1333 } 1334 } 1335 /* We need a close match */ 1336 if (distance < 20) 1337 return near; 1338 else 1339 return NULL; 1340 } 1341 1342 /* 1343 * Find symbols before or equal addr and after addr - in the section sec. 1344 * If we find two symbols with equal offset prefer one with a valid name. 1345 * The ELF format may have a better way to detect what type of symbol 1346 * it is, but this works for now. 1347 **/ 1348 static Elf_Sym *find_elf_symbol2(struct elf_info *elf, Elf_Addr addr, 1349 const char *sec) 1350 { 1351 Elf_Sym *sym; 1352 Elf_Sym *near = NULL; 1353 Elf_Addr distance = ~0; 1354 1355 for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) { 1356 const char *symsec; 1357 1358 if (is_shndx_special(sym->st_shndx)) 1359 continue; 1360 symsec = sec_name(elf, get_secindex(elf, sym)); 1361 if (strcmp(symsec, sec) != 0) 1362 continue; 1363 if (!is_valid_name(elf, sym)) 1364 continue; 1365 if (sym->st_value <= addr) { 1366 if ((addr - sym->st_value) < distance) { 1367 distance = addr - sym->st_value; 1368 near = sym; 1369 } else if ((addr - sym->st_value) == distance) { 1370 near = sym; 1371 } 1372 } 1373 } 1374 return near; 1375 } 1376 1377 /* 1378 * Convert a section name to the function/data attribute 1379 * .init.text => __init 1380 * .memexitconst => __memconst 1381 * etc. 1382 * 1383 * The memory of returned value has been allocated on a heap. The user of this 1384 * method should free it after usage. 1385 */ 1386 static char *sec2annotation(const char *s) 1387 { 1388 if (match(s, init_exit_sections)) { 1389 char *p = NOFAIL(malloc(20)); 1390 char *r = p; 1391 1392 *p++ = '_'; 1393 *p++ = '_'; 1394 if (*s == '.') 1395 s++; 1396 while (*s && *s != '.') 1397 *p++ = *s++; 1398 *p = '\0'; 1399 if (*s == '.') 1400 s++; 1401 if (strstr(s, "rodata") != NULL) 1402 strcat(p, "const "); 1403 else if (strstr(s, "data") != NULL) 1404 strcat(p, "data "); 1405 else 1406 strcat(p, " "); 1407 return r; 1408 } else { 1409 return NOFAIL(strdup("")); 1410 } 1411 } 1412 1413 static int is_function(Elf_Sym *sym) 1414 { 1415 if (sym) 1416 return ELF_ST_TYPE(sym->st_info) == STT_FUNC; 1417 else 1418 return -1; 1419 } 1420 1421 static void print_section_list(const char * const list[20]) 1422 { 1423 const char *const *s = list; 1424 1425 while (*s) { 1426 fprintf(stderr, "%s", *s); 1427 s++; 1428 if (*s) 1429 fprintf(stderr, ", "); 1430 } 1431 fprintf(stderr, "\n"); 1432 } 1433 1434 static inline void get_pretty_name(int is_func, const char** name, const char** name_p) 1435 { 1436 switch (is_func) { 1437 case 0: *name = "variable"; *name_p = ""; break; 1438 case 1: *name = "function"; *name_p = "()"; break; 1439 default: *name = "(unknown reference)"; *name_p = ""; break; 1440 } 1441 } 1442 1443 /* 1444 * Print a warning about a section mismatch. 1445 * Try to find symbols near it so user can find it. 1446 * Check whitelist before warning - it may be a false positive. 1447 */ 1448 static void report_sec_mismatch(const char *modname, 1449 const struct sectioncheck *mismatch, 1450 const char *fromsec, 1451 unsigned long long fromaddr, 1452 const char *fromsym, 1453 int from_is_func, 1454 const char *tosec, const char *tosym, 1455 int to_is_func) 1456 { 1457 const char *from, *from_p; 1458 const char *to, *to_p; 1459 char *prl_from; 1460 char *prl_to; 1461 1462 sec_mismatch_count++; 1463 1464 get_pretty_name(from_is_func, &from, &from_p); 1465 get_pretty_name(to_is_func, &to, &to_p); 1466 1467 warn("%s(%s+0x%llx): Section mismatch in reference from the %s %s%s " 1468 "to the %s %s:%s%s\n", 1469 modname, fromsec, fromaddr, from, fromsym, from_p, to, tosec, 1470 tosym, to_p); 1471 1472 switch (mismatch->mismatch) { 1473 case TEXT_TO_ANY_INIT: 1474 prl_from = sec2annotation(fromsec); 1475 prl_to = sec2annotation(tosec); 1476 fprintf(stderr, 1477 "The function %s%s() references\n" 1478 "the %s %s%s%s.\n" 1479 "This is often because %s lacks a %s\n" 1480 "annotation or the annotation of %s is wrong.\n", 1481 prl_from, fromsym, 1482 to, prl_to, tosym, to_p, 1483 fromsym, prl_to, tosym); 1484 free(prl_from); 1485 free(prl_to); 1486 break; 1487 case DATA_TO_ANY_INIT: { 1488 prl_to = sec2annotation(tosec); 1489 fprintf(stderr, 1490 "The variable %s references\n" 1491 "the %s %s%s%s\n" 1492 "If the reference is valid then annotate the\n" 1493 "variable with __init* or __refdata (see linux/init.h) " 1494 "or name the variable:\n", 1495 fromsym, to, prl_to, tosym, to_p); 1496 print_section_list(mismatch->symbol_white_list); 1497 free(prl_to); 1498 break; 1499 } 1500 case TEXT_TO_ANY_EXIT: 1501 prl_to = sec2annotation(tosec); 1502 fprintf(stderr, 1503 "The function %s() references a %s in an exit section.\n" 1504 "Often the %s %s%s has valid usage outside the exit section\n" 1505 "and the fix is to remove the %sannotation of %s.\n", 1506 fromsym, to, to, tosym, to_p, prl_to, tosym); 1507 free(prl_to); 1508 break; 1509 case DATA_TO_ANY_EXIT: { 1510 prl_to = sec2annotation(tosec); 1511 fprintf(stderr, 1512 "The variable %s references\n" 1513 "the %s %s%s%s\n" 1514 "If the reference is valid then annotate the\n" 1515 "variable with __exit* (see linux/init.h) or " 1516 "name the variable:\n", 1517 fromsym, to, prl_to, tosym, to_p); 1518 print_section_list(mismatch->symbol_white_list); 1519 free(prl_to); 1520 break; 1521 } 1522 case XXXINIT_TO_SOME_INIT: 1523 case XXXEXIT_TO_SOME_EXIT: 1524 prl_from = sec2annotation(fromsec); 1525 prl_to = sec2annotation(tosec); 1526 fprintf(stderr, 1527 "The %s %s%s%s references\n" 1528 "a %s %s%s%s.\n" 1529 "If %s is only used by %s then\n" 1530 "annotate %s with a matching annotation.\n", 1531 from, prl_from, fromsym, from_p, 1532 to, prl_to, tosym, to_p, 1533 tosym, fromsym, tosym); 1534 free(prl_from); 1535 free(prl_to); 1536 break; 1537 case ANY_INIT_TO_ANY_EXIT: 1538 prl_from = sec2annotation(fromsec); 1539 prl_to = sec2annotation(tosec); 1540 fprintf(stderr, 1541 "The %s %s%s%s references\n" 1542 "a %s %s%s%s.\n" 1543 "This is often seen when error handling " 1544 "in the init function\n" 1545 "uses functionality in the exit path.\n" 1546 "The fix is often to remove the %sannotation of\n" 1547 "%s%s so it may be used outside an exit section.\n", 1548 from, prl_from, fromsym, from_p, 1549 to, prl_to, tosym, to_p, 1550 prl_to, tosym, to_p); 1551 free(prl_from); 1552 free(prl_to); 1553 break; 1554 case ANY_EXIT_TO_ANY_INIT: 1555 prl_from = sec2annotation(fromsec); 1556 prl_to = sec2annotation(tosec); 1557 fprintf(stderr, 1558 "The %s %s%s%s references\n" 1559 "a %s %s%s%s.\n" 1560 "This is often seen when error handling " 1561 "in the exit function\n" 1562 "uses functionality in the init path.\n" 1563 "The fix is often to remove the %sannotation of\n" 1564 "%s%s so it may be used outside an init section.\n", 1565 from, prl_from, fromsym, from_p, 1566 to, prl_to, tosym, to_p, 1567 prl_to, tosym, to_p); 1568 free(prl_from); 1569 free(prl_to); 1570 break; 1571 case EXPORT_TO_INIT_EXIT: 1572 prl_to = sec2annotation(tosec); 1573 fprintf(stderr, 1574 "The symbol %s is exported and annotated %s\n" 1575 "Fix this by removing the %sannotation of %s " 1576 "or drop the export.\n", 1577 tosym, prl_to, prl_to, tosym); 1578 free(prl_to); 1579 break; 1580 case EXTABLE_TO_NON_TEXT: 1581 fatal("There's a special handler for this mismatch type, " 1582 "we should never get here."); 1583 break; 1584 } 1585 fprintf(stderr, "\n"); 1586 } 1587 1588 static void default_mismatch_handler(const char *modname, struct elf_info *elf, 1589 const struct sectioncheck* const mismatch, 1590 Elf_Rela *r, Elf_Sym *sym, const char *fromsec) 1591 { 1592 const char *tosec; 1593 Elf_Sym *to; 1594 Elf_Sym *from; 1595 const char *tosym; 1596 const char *fromsym; 1597 1598 from = find_elf_symbol2(elf, r->r_offset, fromsec); 1599 fromsym = sym_name(elf, from); 1600 1601 if (strstarts(fromsym, "reference___initcall")) 1602 return; 1603 1604 tosec = sec_name(elf, get_secindex(elf, sym)); 1605 to = find_elf_symbol(elf, r->r_addend, sym); 1606 tosym = sym_name(elf, to); 1607 1608 /* check whitelist - we may ignore it */ 1609 if (secref_whitelist(mismatch, 1610 fromsec, fromsym, tosec, tosym)) { 1611 report_sec_mismatch(modname, mismatch, 1612 fromsec, r->r_offset, fromsym, 1613 is_function(from), tosec, tosym, 1614 is_function(to)); 1615 } 1616 } 1617 1618 static int is_executable_section(struct elf_info* elf, unsigned int section_index) 1619 { 1620 if (section_index > elf->num_sections) 1621 fatal("section_index is outside elf->num_sections!\n"); 1622 1623 return ((elf->sechdrs[section_index].sh_flags & SHF_EXECINSTR) == SHF_EXECINSTR); 1624 } 1625 1626 /* 1627 * We rely on a gross hack in section_rel[a]() calling find_extable_entry_size() 1628 * to know the sizeof(struct exception_table_entry) for the target architecture. 1629 */ 1630 static unsigned int extable_entry_size = 0; 1631 static void find_extable_entry_size(const char* const sec, const Elf_Rela* r) 1632 { 1633 /* 1634 * If we're currently checking the second relocation within __ex_table, 1635 * that relocation offset tells us the offsetof(struct 1636 * exception_table_entry, fixup) which is equal to sizeof(struct 1637 * exception_table_entry) divided by two. We use that to our advantage 1638 * since there's no portable way to get that size as every architecture 1639 * seems to go with different sized types. Not pretty but better than 1640 * hard-coding the size for every architecture.. 1641 */ 1642 if (!extable_entry_size) 1643 extable_entry_size = r->r_offset * 2; 1644 } 1645 1646 static inline bool is_extable_fault_address(Elf_Rela *r) 1647 { 1648 /* 1649 * extable_entry_size is only discovered after we've handled the 1650 * _second_ relocation in __ex_table, so only abort when we're not 1651 * handling the first reloc and extable_entry_size is zero. 1652 */ 1653 if (r->r_offset && extable_entry_size == 0) 1654 fatal("extable_entry size hasn't been discovered!\n"); 1655 1656 return ((r->r_offset == 0) || 1657 (r->r_offset % extable_entry_size == 0)); 1658 } 1659 1660 #define is_second_extable_reloc(Start, Cur, Sec) \ 1661 (((Cur) == (Start) + 1) && (strcmp("__ex_table", (Sec)) == 0)) 1662 1663 static void report_extable_warnings(const char* modname, struct elf_info* elf, 1664 const struct sectioncheck* const mismatch, 1665 Elf_Rela* r, Elf_Sym* sym, 1666 const char* fromsec, const char* tosec) 1667 { 1668 Elf_Sym* fromsym = find_elf_symbol2(elf, r->r_offset, fromsec); 1669 const char* fromsym_name = sym_name(elf, fromsym); 1670 Elf_Sym* tosym = find_elf_symbol(elf, r->r_addend, sym); 1671 const char* tosym_name = sym_name(elf, tosym); 1672 const char* from_pretty_name; 1673 const char* from_pretty_name_p; 1674 const char* to_pretty_name; 1675 const char* to_pretty_name_p; 1676 1677 get_pretty_name(is_function(fromsym), 1678 &from_pretty_name, &from_pretty_name_p); 1679 get_pretty_name(is_function(tosym), 1680 &to_pretty_name, &to_pretty_name_p); 1681 1682 warn("%s(%s+0x%lx): Section mismatch in reference" 1683 " from the %s %s%s to the %s %s:%s%s\n", 1684 modname, fromsec, (long)r->r_offset, from_pretty_name, 1685 fromsym_name, from_pretty_name_p, 1686 to_pretty_name, tosec, tosym_name, to_pretty_name_p); 1687 1688 if (!match(tosec, mismatch->bad_tosec) && 1689 is_executable_section(elf, get_secindex(elf, sym))) 1690 fprintf(stderr, 1691 "The relocation at %s+0x%lx references\n" 1692 "section \"%s\" which is not in the list of\n" 1693 "authorized sections. If you're adding a new section\n" 1694 "and/or if this reference is valid, add \"%s\" to the\n" 1695 "list of authorized sections to jump to on fault.\n" 1696 "This can be achieved by adding \"%s\" to \n" 1697 "OTHER_TEXT_SECTIONS in scripts/mod/modpost.c.\n", 1698 fromsec, (long)r->r_offset, tosec, tosec, tosec); 1699 } 1700 1701 static void extable_mismatch_handler(const char* modname, struct elf_info *elf, 1702 const struct sectioncheck* const mismatch, 1703 Elf_Rela* r, Elf_Sym* sym, 1704 const char *fromsec) 1705 { 1706 const char* tosec = sec_name(elf, get_secindex(elf, sym)); 1707 1708 sec_mismatch_count++; 1709 1710 report_extable_warnings(modname, elf, mismatch, r, sym, fromsec, tosec); 1711 1712 if (match(tosec, mismatch->bad_tosec)) 1713 fatal("The relocation at %s+0x%lx references\n" 1714 "section \"%s\" which is black-listed.\n" 1715 "Something is seriously wrong and should be fixed.\n" 1716 "You might get more information about where this is\n" 1717 "coming from by using scripts/check_extable.sh %s\n", 1718 fromsec, (long)r->r_offset, tosec, modname); 1719 else if (!is_executable_section(elf, get_secindex(elf, sym))) { 1720 if (is_extable_fault_address(r)) 1721 fatal("The relocation at %s+0x%lx references\n" 1722 "section \"%s\" which is not executable, IOW\n" 1723 "it is not possible for the kernel to fault\n" 1724 "at that address. Something is seriously wrong\n" 1725 "and should be fixed.\n", 1726 fromsec, (long)r->r_offset, tosec); 1727 else 1728 fatal("The relocation at %s+0x%lx references\n" 1729 "section \"%s\" which is not executable, IOW\n" 1730 "the kernel will fault if it ever tries to\n" 1731 "jump to it. Something is seriously wrong\n" 1732 "and should be fixed.\n", 1733 fromsec, (long)r->r_offset, tosec); 1734 } 1735 } 1736 1737 static void check_section_mismatch(const char *modname, struct elf_info *elf, 1738 Elf_Rela *r, Elf_Sym *sym, const char *fromsec) 1739 { 1740 const char *tosec = sec_name(elf, get_secindex(elf, sym)); 1741 const struct sectioncheck *mismatch = section_mismatch(fromsec, tosec); 1742 1743 if (mismatch) { 1744 if (mismatch->handler) 1745 mismatch->handler(modname, elf, mismatch, 1746 r, sym, fromsec); 1747 else 1748 default_mismatch_handler(modname, elf, mismatch, 1749 r, sym, fromsec); 1750 } 1751 } 1752 1753 static unsigned int *reloc_location(struct elf_info *elf, 1754 Elf_Shdr *sechdr, Elf_Rela *r) 1755 { 1756 Elf_Shdr *sechdrs = elf->sechdrs; 1757 int section = sechdr->sh_info; 1758 1759 return (void *)elf->hdr + sechdrs[section].sh_offset + 1760 r->r_offset; 1761 } 1762 1763 static int addend_386_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r) 1764 { 1765 unsigned int r_typ = ELF_R_TYPE(r->r_info); 1766 unsigned int *location = reloc_location(elf, sechdr, r); 1767 1768 switch (r_typ) { 1769 case R_386_32: 1770 r->r_addend = TO_NATIVE(*location); 1771 break; 1772 case R_386_PC32: 1773 r->r_addend = TO_NATIVE(*location) + 4; 1774 /* For CONFIG_RELOCATABLE=y */ 1775 if (elf->hdr->e_type == ET_EXEC) 1776 r->r_addend += r->r_offset; 1777 break; 1778 } 1779 return 0; 1780 } 1781 1782 #ifndef R_ARM_CALL 1783 #define R_ARM_CALL 28 1784 #endif 1785 #ifndef R_ARM_JUMP24 1786 #define R_ARM_JUMP24 29 1787 #endif 1788 1789 #ifndef R_ARM_THM_CALL 1790 #define R_ARM_THM_CALL 10 1791 #endif 1792 #ifndef R_ARM_THM_JUMP24 1793 #define R_ARM_THM_JUMP24 30 1794 #endif 1795 #ifndef R_ARM_THM_JUMP19 1796 #define R_ARM_THM_JUMP19 51 1797 #endif 1798 1799 static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r) 1800 { 1801 unsigned int r_typ = ELF_R_TYPE(r->r_info); 1802 1803 switch (r_typ) { 1804 case R_ARM_ABS32: 1805 /* From ARM ABI: (S + A) | T */ 1806 r->r_addend = (int)(long) 1807 (elf->symtab_start + ELF_R_SYM(r->r_info)); 1808 break; 1809 case R_ARM_PC24: 1810 case R_ARM_CALL: 1811 case R_ARM_JUMP24: 1812 case R_ARM_THM_CALL: 1813 case R_ARM_THM_JUMP24: 1814 case R_ARM_THM_JUMP19: 1815 /* From ARM ABI: ((S + A) | T) - P */ 1816 r->r_addend = (int)(long)(elf->hdr + 1817 sechdr->sh_offset + 1818 (r->r_offset - sechdr->sh_addr)); 1819 break; 1820 default: 1821 return 1; 1822 } 1823 return 0; 1824 } 1825 1826 static int addend_mips_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r) 1827 { 1828 unsigned int r_typ = ELF_R_TYPE(r->r_info); 1829 unsigned int *location = reloc_location(elf, sechdr, r); 1830 unsigned int inst; 1831 1832 if (r_typ == R_MIPS_HI16) 1833 return 1; /* skip this */ 1834 inst = TO_NATIVE(*location); 1835 switch (r_typ) { 1836 case R_MIPS_LO16: 1837 r->r_addend = inst & 0xffff; 1838 break; 1839 case R_MIPS_26: 1840 r->r_addend = (inst & 0x03ffffff) << 2; 1841 break; 1842 case R_MIPS_32: 1843 r->r_addend = inst; 1844 break; 1845 } 1846 return 0; 1847 } 1848 1849 static void section_rela(const char *modname, struct elf_info *elf, 1850 Elf_Shdr *sechdr) 1851 { 1852 Elf_Sym *sym; 1853 Elf_Rela *rela; 1854 Elf_Rela r; 1855 unsigned int r_sym; 1856 const char *fromsec; 1857 1858 Elf_Rela *start = (void *)elf->hdr + sechdr->sh_offset; 1859 Elf_Rela *stop = (void *)start + sechdr->sh_size; 1860 1861 fromsec = sech_name(elf, sechdr); 1862 fromsec += strlen(".rela"); 1863 /* if from section (name) is know good then skip it */ 1864 if (match(fromsec, section_white_list)) 1865 return; 1866 1867 for (rela = start; rela < stop; rela++) { 1868 r.r_offset = TO_NATIVE(rela->r_offset); 1869 #if KERNEL_ELFCLASS == ELFCLASS64 1870 if (elf->hdr->e_machine == EM_MIPS) { 1871 unsigned int r_typ; 1872 r_sym = ELF64_MIPS_R_SYM(rela->r_info); 1873 r_sym = TO_NATIVE(r_sym); 1874 r_typ = ELF64_MIPS_R_TYPE(rela->r_info); 1875 r.r_info = ELF64_R_INFO(r_sym, r_typ); 1876 } else { 1877 r.r_info = TO_NATIVE(rela->r_info); 1878 r_sym = ELF_R_SYM(r.r_info); 1879 } 1880 #else 1881 r.r_info = TO_NATIVE(rela->r_info); 1882 r_sym = ELF_R_SYM(r.r_info); 1883 #endif 1884 r.r_addend = TO_NATIVE(rela->r_addend); 1885 sym = elf->symtab_start + r_sym; 1886 /* Skip special sections */ 1887 if (is_shndx_special(sym->st_shndx)) 1888 continue; 1889 if (is_second_extable_reloc(start, rela, fromsec)) 1890 find_extable_entry_size(fromsec, &r); 1891 check_section_mismatch(modname, elf, &r, sym, fromsec); 1892 } 1893 } 1894 1895 static void section_rel(const char *modname, struct elf_info *elf, 1896 Elf_Shdr *sechdr) 1897 { 1898 Elf_Sym *sym; 1899 Elf_Rel *rel; 1900 Elf_Rela r; 1901 unsigned int r_sym; 1902 const char *fromsec; 1903 1904 Elf_Rel *start = (void *)elf->hdr + sechdr->sh_offset; 1905 Elf_Rel *stop = (void *)start + sechdr->sh_size; 1906 1907 fromsec = sech_name(elf, sechdr); 1908 fromsec += strlen(".rel"); 1909 /* if from section (name) is know good then skip it */ 1910 if (match(fromsec, section_white_list)) 1911 return; 1912 1913 for (rel = start; rel < stop; rel++) { 1914 r.r_offset = TO_NATIVE(rel->r_offset); 1915 #if KERNEL_ELFCLASS == ELFCLASS64 1916 if (elf->hdr->e_machine == EM_MIPS) { 1917 unsigned int r_typ; 1918 r_sym = ELF64_MIPS_R_SYM(rel->r_info); 1919 r_sym = TO_NATIVE(r_sym); 1920 r_typ = ELF64_MIPS_R_TYPE(rel->r_info); 1921 r.r_info = ELF64_R_INFO(r_sym, r_typ); 1922 } else { 1923 r.r_info = TO_NATIVE(rel->r_info); 1924 r_sym = ELF_R_SYM(r.r_info); 1925 } 1926 #else 1927 r.r_info = TO_NATIVE(rel->r_info); 1928 r_sym = ELF_R_SYM(r.r_info); 1929 #endif 1930 r.r_addend = 0; 1931 switch (elf->hdr->e_machine) { 1932 case EM_386: 1933 if (addend_386_rel(elf, sechdr, &r)) 1934 continue; 1935 break; 1936 case EM_ARM: 1937 if (addend_arm_rel(elf, sechdr, &r)) 1938 continue; 1939 break; 1940 case EM_MIPS: 1941 if (addend_mips_rel(elf, sechdr, &r)) 1942 continue; 1943 break; 1944 } 1945 sym = elf->symtab_start + r_sym; 1946 /* Skip special sections */ 1947 if (is_shndx_special(sym->st_shndx)) 1948 continue; 1949 if (is_second_extable_reloc(start, rel, fromsec)) 1950 find_extable_entry_size(fromsec, &r); 1951 check_section_mismatch(modname, elf, &r, sym, fromsec); 1952 } 1953 } 1954 1955 /** 1956 * A module includes a number of sections that are discarded 1957 * either when loaded or when used as built-in. 1958 * For loaded modules all functions marked __init and all data 1959 * marked __initdata will be discarded when the module has been initialized. 1960 * Likewise for modules used built-in the sections marked __exit 1961 * are discarded because __exit marked function are supposed to be called 1962 * only when a module is unloaded which never happens for built-in modules. 1963 * The check_sec_ref() function traverses all relocation records 1964 * to find all references to a section that reference a section that will 1965 * be discarded and warns about it. 1966 **/ 1967 static void check_sec_ref(struct module *mod, const char *modname, 1968 struct elf_info *elf) 1969 { 1970 int i; 1971 Elf_Shdr *sechdrs = elf->sechdrs; 1972 1973 /* Walk through all sections */ 1974 for (i = 0; i < elf->num_sections; i++) { 1975 check_section(modname, elf, &elf->sechdrs[i]); 1976 /* We want to process only relocation sections and not .init */ 1977 if (sechdrs[i].sh_type == SHT_RELA) 1978 section_rela(modname, elf, &elf->sechdrs[i]); 1979 else if (sechdrs[i].sh_type == SHT_REL) 1980 section_rel(modname, elf, &elf->sechdrs[i]); 1981 } 1982 } 1983 1984 static char *remove_dot(char *s) 1985 { 1986 size_t n = strcspn(s, "."); 1987 1988 if (n && s[n]) { 1989 size_t m = strspn(s + n + 1, "0123456789"); 1990 if (m && (s[n + m] == '.' || s[n + m] == 0)) 1991 s[n] = 0; 1992 } 1993 return s; 1994 } 1995 1996 static void read_symbols(const char *modname) 1997 { 1998 const char *symname; 1999 char *version; 2000 char *license; 2001 char *namespace; 2002 struct module *mod; 2003 struct elf_info info = { }; 2004 Elf_Sym *sym; 2005 2006 if (!parse_elf(&info, modname)) 2007 return; 2008 2009 mod = new_module(modname); 2010 2011 /* When there's no vmlinux, don't print warnings about 2012 * unresolved symbols (since there'll be too many ;) */ 2013 if (is_vmlinux(modname)) { 2014 have_vmlinux = 1; 2015 mod->skip = 1; 2016 } 2017 2018 license = get_modinfo(&info, "license"); 2019 if (!license && !is_vmlinux(modname)) 2020 warn("modpost: missing MODULE_LICENSE() in %s\n" 2021 "see include/linux/module.h for " 2022 "more information\n", modname); 2023 while (license) { 2024 if (license_is_gpl_compatible(license)) 2025 mod->gpl_compatible = 1; 2026 else { 2027 mod->gpl_compatible = 0; 2028 break; 2029 } 2030 license = get_next_modinfo(&info, "license", license); 2031 } 2032 2033 namespace = get_modinfo(&info, "import_ns"); 2034 while (namespace) { 2035 add_namespace(&mod->imported_namespaces, namespace); 2036 namespace = get_next_modinfo(&info, "import_ns", namespace); 2037 } 2038 2039 for (sym = info.symtab_start; sym < info.symtab_stop; sym++) { 2040 symname = remove_dot(info.strtab + sym->st_name); 2041 2042 handle_modversions(mod, &info, sym, symname); 2043 handle_moddevtable(mod, &info, sym, symname); 2044 } 2045 2046 // check for static EXPORT_SYMBOL_* functions && global vars 2047 for (sym = info.symtab_start; sym < info.symtab_stop; sym++) { 2048 unsigned char bind = ELF_ST_BIND(sym->st_info); 2049 2050 if (bind == STB_GLOBAL || bind == STB_WEAK) { 2051 struct symbol *s = 2052 find_symbol(remove_dot(info.strtab + 2053 sym->st_name)); 2054 2055 if (s) 2056 s->is_static = 0; 2057 } 2058 } 2059 2060 if (!is_vmlinux(modname) || vmlinux_section_warnings) 2061 check_sec_ref(mod, modname, &info); 2062 2063 version = get_modinfo(&info, "version"); 2064 if (version) 2065 maybe_frob_rcs_version(modname, version, info.modinfo, 2066 version - (char *)info.hdr); 2067 if (version || (all_versions && !is_vmlinux(modname))) 2068 get_src_version(modname, mod->srcversion, 2069 sizeof(mod->srcversion)-1); 2070 2071 parse_elf_finish(&info); 2072 2073 /* Our trick to get versioning for module struct etc. - it's 2074 * never passed as an argument to an exported function, so 2075 * the automatic versioning doesn't pick it up, but it's really 2076 * important anyhow */ 2077 if (modversions) 2078 mod->unres = alloc_symbol("module_layout", 0, mod->unres); 2079 } 2080 2081 static void read_symbols_from_files(const char *filename) 2082 { 2083 FILE *in = stdin; 2084 char fname[PATH_MAX]; 2085 2086 if (strcmp(filename, "-") != 0) { 2087 in = fopen(filename, "r"); 2088 if (!in) 2089 fatal("Can't open filenames file %s: %m", filename); 2090 } 2091 2092 while (fgets(fname, PATH_MAX, in) != NULL) { 2093 if (strends(fname, "\n")) 2094 fname[strlen(fname)-1] = '\0'; 2095 read_symbols(fname); 2096 } 2097 2098 if (in != stdin) 2099 fclose(in); 2100 } 2101 2102 #define SZ 500 2103 2104 /* We first write the generated file into memory using the 2105 * following helper, then compare to the file on disk and 2106 * only update the later if anything changed */ 2107 2108 void __attribute__((format(printf, 2, 3))) buf_printf(struct buffer *buf, 2109 const char *fmt, ...) 2110 { 2111 char tmp[SZ]; 2112 int len; 2113 va_list ap; 2114 2115 va_start(ap, fmt); 2116 len = vsnprintf(tmp, SZ, fmt, ap); 2117 buf_write(buf, tmp, len); 2118 va_end(ap); 2119 } 2120 2121 void buf_write(struct buffer *buf, const char *s, int len) 2122 { 2123 if (buf->size - buf->pos < len) { 2124 buf->size += len + SZ; 2125 buf->p = NOFAIL(realloc(buf->p, buf->size)); 2126 } 2127 strncpy(buf->p + buf->pos, s, len); 2128 buf->pos += len; 2129 } 2130 2131 static void check_for_gpl_usage(enum export exp, const char *m, const char *s) 2132 { 2133 const char *e = is_vmlinux(m) ?"":".ko"; 2134 2135 switch (exp) { 2136 case export_gpl: 2137 fatal("modpost: GPL-incompatible module %s%s " 2138 "uses GPL-only symbol '%s'\n", m, e, s); 2139 break; 2140 case export_unused_gpl: 2141 fatal("modpost: GPL-incompatible module %s%s " 2142 "uses GPL-only symbol marked UNUSED '%s'\n", m, e, s); 2143 break; 2144 case export_gpl_future: 2145 warn("modpost: GPL-incompatible module %s%s " 2146 "uses future GPL-only symbol '%s'\n", m, e, s); 2147 break; 2148 case export_plain: 2149 case export_unused: 2150 case export_unknown: 2151 /* ignore */ 2152 break; 2153 } 2154 } 2155 2156 static void check_for_unused(enum export exp, const char *m, const char *s) 2157 { 2158 const char *e = is_vmlinux(m) ?"":".ko"; 2159 2160 switch (exp) { 2161 case export_unused: 2162 case export_unused_gpl: 2163 warn("modpost: module %s%s " 2164 "uses symbol '%s' marked UNUSED\n", m, e, s); 2165 break; 2166 default: 2167 /* ignore */ 2168 break; 2169 } 2170 } 2171 2172 static int check_exports(struct module *mod) 2173 { 2174 struct symbol *s, *exp; 2175 int err = 0; 2176 2177 for (s = mod->unres; s; s = s->next) { 2178 const char *basename; 2179 exp = find_symbol(s->name); 2180 if (!exp || exp->module == mod) { 2181 if (have_vmlinux && !s->weak) { 2182 if (warn_unresolved) { 2183 warn("\"%s\" [%s.ko] undefined!\n", 2184 s->name, mod->name); 2185 } else { 2186 merror("\"%s\" [%s.ko] undefined!\n", 2187 s->name, mod->name); 2188 err = 1; 2189 } 2190 } 2191 continue; 2192 } 2193 basename = strrchr(mod->name, '/'); 2194 if (basename) 2195 basename++; 2196 else 2197 basename = mod->name; 2198 2199 if (exp->namespace && exp->namespace[0]) { 2200 add_namespace(&mod->required_namespaces, 2201 exp->namespace); 2202 2203 if (!write_namespace_deps && 2204 !module_imports_namespace(mod, exp->namespace)) { 2205 warn("module %s uses symbol %s from namespace %s, but does not import it.\n", 2206 basename, exp->name, exp->namespace); 2207 } 2208 } 2209 2210 if (!mod->gpl_compatible) 2211 check_for_gpl_usage(exp->export, basename, exp->name); 2212 check_for_unused(exp->export, basename, exp->name); 2213 } 2214 2215 return err; 2216 } 2217 2218 static int check_modname_len(struct module *mod) 2219 { 2220 const char *mod_name; 2221 2222 mod_name = strrchr(mod->name, '/'); 2223 if (mod_name == NULL) 2224 mod_name = mod->name; 2225 else 2226 mod_name++; 2227 if (strlen(mod_name) >= MODULE_NAME_LEN) { 2228 merror("module name is too long [%s.ko]\n", mod->name); 2229 return 1; 2230 } 2231 2232 return 0; 2233 } 2234 2235 /** 2236 * Header for the generated file 2237 **/ 2238 static void add_header(struct buffer *b, struct module *mod) 2239 { 2240 buf_printf(b, "#include <linux/build-salt.h>\n"); 2241 buf_printf(b, "#include <linux/module.h>\n"); 2242 buf_printf(b, "#include <linux/vermagic.h>\n"); 2243 buf_printf(b, "#include <linux/compiler.h>\n"); 2244 buf_printf(b, "\n"); 2245 buf_printf(b, "BUILD_SALT;\n"); 2246 buf_printf(b, "\n"); 2247 buf_printf(b, "MODULE_INFO(vermagic, VERMAGIC_STRING);\n"); 2248 buf_printf(b, "MODULE_INFO(name, KBUILD_MODNAME);\n"); 2249 buf_printf(b, "\n"); 2250 buf_printf(b, "__visible struct module __this_module\n"); 2251 buf_printf(b, "__section(.gnu.linkonce.this_module) = {\n"); 2252 buf_printf(b, "\t.name = KBUILD_MODNAME,\n"); 2253 if (mod->has_init) 2254 buf_printf(b, "\t.init = init_module,\n"); 2255 if (mod->has_cleanup) 2256 buf_printf(b, "#ifdef CONFIG_MODULE_UNLOAD\n" 2257 "\t.exit = cleanup_module,\n" 2258 "#endif\n"); 2259 buf_printf(b, "\t.arch = MODULE_ARCH_INIT,\n"); 2260 buf_printf(b, "};\n"); 2261 } 2262 2263 static void add_intree_flag(struct buffer *b, int is_intree) 2264 { 2265 if (is_intree) 2266 buf_printf(b, "\nMODULE_INFO(intree, \"Y\");\n"); 2267 } 2268 2269 /* Cannot check for assembler */ 2270 static void add_retpoline(struct buffer *b) 2271 { 2272 buf_printf(b, "\n#ifdef CONFIG_RETPOLINE\n"); 2273 buf_printf(b, "MODULE_INFO(retpoline, \"Y\");\n"); 2274 buf_printf(b, "#endif\n"); 2275 } 2276 2277 static void add_staging_flag(struct buffer *b, const char *name) 2278 { 2279 if (strstarts(name, "drivers/staging")) 2280 buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n"); 2281 } 2282 2283 /** 2284 * Record CRCs for unresolved symbols 2285 **/ 2286 static int add_versions(struct buffer *b, struct module *mod) 2287 { 2288 struct symbol *s, *exp; 2289 int err = 0; 2290 2291 for (s = mod->unres; s; s = s->next) { 2292 exp = find_symbol(s->name); 2293 if (!exp || exp->module == mod) 2294 continue; 2295 s->module = exp->module; 2296 s->crc_valid = exp->crc_valid; 2297 s->crc = exp->crc; 2298 } 2299 2300 if (!modversions) 2301 return err; 2302 2303 buf_printf(b, "\n"); 2304 buf_printf(b, "static const struct modversion_info ____versions[]\n"); 2305 buf_printf(b, "__used __section(__versions) = {\n"); 2306 2307 for (s = mod->unres; s; s = s->next) { 2308 if (!s->module) 2309 continue; 2310 if (!s->crc_valid) { 2311 warn("\"%s\" [%s.ko] has no CRC!\n", 2312 s->name, mod->name); 2313 continue; 2314 } 2315 if (strlen(s->name) >= MODULE_NAME_LEN) { 2316 merror("too long symbol \"%s\" [%s.ko]\n", 2317 s->name, mod->name); 2318 err = 1; 2319 break; 2320 } 2321 buf_printf(b, "\t{ %#8x, \"%s\" },\n", 2322 s->crc, s->name); 2323 } 2324 2325 buf_printf(b, "};\n"); 2326 2327 return err; 2328 } 2329 2330 static void add_depends(struct buffer *b, struct module *mod) 2331 { 2332 struct symbol *s; 2333 int first = 1; 2334 2335 /* Clear ->seen flag of modules that own symbols needed by this. */ 2336 for (s = mod->unres; s; s = s->next) 2337 if (s->module) 2338 s->module->seen = is_vmlinux(s->module->name); 2339 2340 buf_printf(b, "\n"); 2341 buf_printf(b, "MODULE_INFO(depends, \""); 2342 for (s = mod->unres; s; s = s->next) { 2343 const char *p; 2344 if (!s->module) 2345 continue; 2346 2347 if (s->module->seen) 2348 continue; 2349 2350 s->module->seen = 1; 2351 p = strrchr(s->module->name, '/'); 2352 if (p) 2353 p++; 2354 else 2355 p = s->module->name; 2356 buf_printf(b, "%s%s", first ? "" : ",", p); 2357 first = 0; 2358 } 2359 buf_printf(b, "\");\n"); 2360 } 2361 2362 static void add_srcversion(struct buffer *b, struct module *mod) 2363 { 2364 if (mod->srcversion[0]) { 2365 buf_printf(b, "\n"); 2366 buf_printf(b, "MODULE_INFO(srcversion, \"%s\");\n", 2367 mod->srcversion); 2368 } 2369 } 2370 2371 static void write_if_changed(struct buffer *b, const char *fname) 2372 { 2373 char *tmp; 2374 FILE *file; 2375 struct stat st; 2376 2377 file = fopen(fname, "r"); 2378 if (!file) 2379 goto write; 2380 2381 if (fstat(fileno(file), &st) < 0) 2382 goto close_write; 2383 2384 if (st.st_size != b->pos) 2385 goto close_write; 2386 2387 tmp = NOFAIL(malloc(b->pos)); 2388 if (fread(tmp, 1, b->pos, file) != b->pos) 2389 goto free_write; 2390 2391 if (memcmp(tmp, b->p, b->pos) != 0) 2392 goto free_write; 2393 2394 free(tmp); 2395 fclose(file); 2396 return; 2397 2398 free_write: 2399 free(tmp); 2400 close_write: 2401 fclose(file); 2402 write: 2403 file = fopen(fname, "w"); 2404 if (!file) { 2405 perror(fname); 2406 exit(1); 2407 } 2408 if (fwrite(b->p, 1, b->pos, file) != b->pos) { 2409 perror(fname); 2410 exit(1); 2411 } 2412 fclose(file); 2413 } 2414 2415 /* parse Module.symvers file. line format: 2416 * 0x12345678<tab>symbol<tab>module[[<tab>export]<tab>something] 2417 **/ 2418 static void read_dump(const char *fname, unsigned int kernel) 2419 { 2420 unsigned long size, pos = 0; 2421 void *file = grab_file(fname, &size); 2422 char *line; 2423 2424 if (!file) 2425 /* No symbol versions, silently ignore */ 2426 return; 2427 2428 while ((line = get_next_line(&pos, file, size))) { 2429 char *symname, *namespace, *modname, *d, *export, *end; 2430 unsigned int crc; 2431 struct module *mod; 2432 struct symbol *s; 2433 2434 if (!(symname = strchr(line, '\t'))) 2435 goto fail; 2436 *symname++ = '\0'; 2437 if (!(namespace = strchr(symname, '\t'))) 2438 goto fail; 2439 *namespace++ = '\0'; 2440 if (!(modname = strchr(namespace, '\t'))) 2441 goto fail; 2442 *modname++ = '\0'; 2443 if ((export = strchr(modname, '\t')) != NULL) 2444 *export++ = '\0'; 2445 if (export && ((end = strchr(export, '\t')) != NULL)) 2446 *end = '\0'; 2447 crc = strtoul(line, &d, 16); 2448 if (*symname == '\0' || *modname == '\0' || *d != '\0') 2449 goto fail; 2450 mod = find_module(modname); 2451 if (!mod) { 2452 if (is_vmlinux(modname)) 2453 have_vmlinux = 1; 2454 mod = new_module(modname); 2455 mod->skip = 1; 2456 } 2457 s = sym_add_exported(symname, namespace, mod, 2458 export_no(export)); 2459 s->kernel = kernel; 2460 s->preloaded = 1; 2461 s->is_static = 0; 2462 sym_update_crc(symname, mod, crc, export_no(export)); 2463 } 2464 release_file(file, size); 2465 return; 2466 fail: 2467 release_file(file, size); 2468 fatal("parse error in symbol dump file\n"); 2469 } 2470 2471 /* For normal builds always dump all symbols. 2472 * For external modules only dump symbols 2473 * that are not read from kernel Module.symvers. 2474 **/ 2475 static int dump_sym(struct symbol *sym) 2476 { 2477 if (!external_module) 2478 return 1; 2479 if (sym->vmlinux || sym->kernel) 2480 return 0; 2481 return 1; 2482 } 2483 2484 static void write_dump(const char *fname) 2485 { 2486 struct buffer buf = { }; 2487 struct symbol *symbol; 2488 const char *namespace; 2489 int n; 2490 2491 for (n = 0; n < SYMBOL_HASH_SIZE ; n++) { 2492 symbol = symbolhash[n]; 2493 while (symbol) { 2494 if (dump_sym(symbol)) { 2495 namespace = symbol->namespace; 2496 buf_printf(&buf, "0x%08x\t%s\t%s\t%s\t%s\n", 2497 symbol->crc, symbol->name, 2498 namespace ? namespace : "", 2499 symbol->module->name, 2500 export_str(symbol->export)); 2501 } 2502 symbol = symbol->next; 2503 } 2504 } 2505 write_if_changed(&buf, fname); 2506 free(buf.p); 2507 } 2508 2509 static void write_namespace_deps_files(void) 2510 { 2511 struct module *mod; 2512 struct namespace_list *ns; 2513 struct buffer ns_deps_buf = {}; 2514 2515 for (mod = modules; mod; mod = mod->next) { 2516 char fname[PATH_MAX]; 2517 2518 if (mod->skip) 2519 continue; 2520 2521 ns_deps_buf.pos = 0; 2522 2523 for (ns = mod->required_namespaces; ns; ns = ns->next) 2524 buf_printf(&ns_deps_buf, "%s\n", ns->namespace); 2525 2526 if (ns_deps_buf.pos == 0) 2527 continue; 2528 2529 sprintf(fname, "%s.ns_deps", mod->name); 2530 write_if_changed(&ns_deps_buf, fname); 2531 } 2532 } 2533 2534 struct ext_sym_list { 2535 struct ext_sym_list *next; 2536 const char *file; 2537 }; 2538 2539 int main(int argc, char **argv) 2540 { 2541 struct module *mod; 2542 struct buffer buf = { }; 2543 char *kernel_read = NULL, *module_read = NULL; 2544 char *dump_write = NULL, *files_source = NULL; 2545 int opt; 2546 int err; 2547 int n; 2548 struct ext_sym_list *extsym_iter; 2549 struct ext_sym_list *extsym_start = NULL; 2550 2551 while ((opt = getopt(argc, argv, "i:I:e:mnsT:o:awEd")) != -1) { 2552 switch (opt) { 2553 case 'i': 2554 kernel_read = optarg; 2555 break; 2556 case 'I': 2557 module_read = optarg; 2558 external_module = 1; 2559 break; 2560 case 'e': 2561 external_module = 1; 2562 extsym_iter = 2563 NOFAIL(malloc(sizeof(*extsym_iter))); 2564 extsym_iter->next = extsym_start; 2565 extsym_iter->file = optarg; 2566 extsym_start = extsym_iter; 2567 break; 2568 case 'm': 2569 modversions = 1; 2570 break; 2571 case 'n': 2572 ignore_missing_files = 1; 2573 break; 2574 case 'o': 2575 dump_write = optarg; 2576 break; 2577 case 'a': 2578 all_versions = 1; 2579 break; 2580 case 's': 2581 vmlinux_section_warnings = 0; 2582 break; 2583 case 'T': 2584 files_source = optarg; 2585 break; 2586 case 'w': 2587 warn_unresolved = 1; 2588 break; 2589 case 'E': 2590 sec_mismatch_fatal = 1; 2591 break; 2592 case 'd': 2593 write_namespace_deps = 1; 2594 break; 2595 default: 2596 exit(1); 2597 } 2598 } 2599 2600 if (kernel_read) 2601 read_dump(kernel_read, 1); 2602 if (module_read) 2603 read_dump(module_read, 0); 2604 while (extsym_start) { 2605 read_dump(extsym_start->file, 0); 2606 extsym_iter = extsym_start->next; 2607 free(extsym_start); 2608 extsym_start = extsym_iter; 2609 } 2610 2611 while (optind < argc) 2612 read_symbols(argv[optind++]); 2613 2614 if (files_source) 2615 read_symbols_from_files(files_source); 2616 2617 err = 0; 2618 2619 for (mod = modules; mod; mod = mod->next) { 2620 char fname[PATH_MAX]; 2621 2622 if (mod->skip) 2623 continue; 2624 2625 buf.pos = 0; 2626 2627 err |= check_modname_len(mod); 2628 err |= check_exports(mod); 2629 if (write_namespace_deps) 2630 continue; 2631 2632 add_header(&buf, mod); 2633 add_intree_flag(&buf, !external_module); 2634 add_retpoline(&buf); 2635 add_staging_flag(&buf, mod->name); 2636 err |= add_versions(&buf, mod); 2637 add_depends(&buf, mod); 2638 add_moddevtable(&buf, mod); 2639 add_srcversion(&buf, mod); 2640 2641 sprintf(fname, "%s.mod.c", mod->name); 2642 write_if_changed(&buf, fname); 2643 } 2644 2645 if (write_namespace_deps) { 2646 write_namespace_deps_files(); 2647 return 0; 2648 } 2649 2650 if (dump_write) 2651 write_dump(dump_write); 2652 if (sec_mismatch_count && sec_mismatch_fatal) 2653 fatal("modpost: Section mismatches detected.\n" 2654 "Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to allow them.\n"); 2655 for (n = 0; n < SYMBOL_HASH_SIZE; n++) { 2656 struct symbol *s; 2657 2658 for (s = symbolhash[n]; s; s = s->next) { 2659 /* 2660 * Do not check "vmlinux". This avoids the same warnings 2661 * shown twice, and false-positives for ARCH=um. 2662 */ 2663 if (is_vmlinux(s->module->name) && !s->module->is_dot_o) 2664 continue; 2665 2666 if (s->is_static) 2667 warn("\"%s\" [%s] is a static %s\n", 2668 s->name, s->module->name, 2669 export_str(s->export)); 2670 } 2671 } 2672 2673 free(buf.p); 2674 2675 return err; 2676 } 2677