arch/x86/tools/relocs.c

   1 #include <stdio.h>
   2 #include <stdarg.h>
   3 #include <stdlib.h>
   4 #include <stdint.h>
   5 #include <string.h>
   6 #include <errno.h>
   7 #include <unistd.h>
   8 #include <elf.h>
   9 #include <byteswap.h>
  10 #define USE_BSD
  11 #include <endian.h>
  12 #include <regex.h>
  13 #include <tools/le_byteshift.h>
  14
  15 static void die(char *fmt, ...);
  16
  17 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
  18 static Elf32_Ehdr ehdr;
  19 static unsigned long reloc_count, reloc_idx;
  20 static unsigned long *relocs;
  21 static unsigned long reloc16_count, reloc16_idx;
  22 static unsigned long *relocs16;
  23
  24 struct section {
  25         Elf32_Shdr     shdr;
  26         struct section *link;
  27         Elf32_Sym      *symtab;
  28         Elf32_Rel      *reltab;
  29         char           *strtab;
  30 };
  31 static struct section *secs;
  32
  33 enum symtype {
  34         S_ABS,
  35         S_REL,
  36         S_SEG,
  37         S_LIN,
  38         S_NSYMTYPES
  39 };
  40
  41 static const char * const sym_regex_kernel[S_NSYMTYPES] = {
  42 /*
  43  * Following symbols have been audited. There values are constant and do
  44  * not change if bzImage is loaded at a different physical address than
  45  * the address for which it has been compiled. Don't warn user about
  46  * absolute relocations present w.r.t these symbols.
  47  */
  48         [S_ABS] =
  49         "^(xen_irq_disable_direct_reloc$|"
  50         "xen_save_fl_direct_reloc$|"
  51         "VDSO|"
  52         "__crc_)",
  53
  54 /*
  55  * These symbols are known to be relative, even if the linker marks them
  56  * as absolute (typically defined outside any section in the linker script.)
  57  */
  58         [S_REL] =
  59         "^_end$",
  60 };
  61
  62
  63 static const char * const sym_regex_realmode[S_NSYMTYPES] = {
  64 /*
  65  * These are 16-bit segment symbols when compiling 16-bit code.
  66  */
  67         [S_SEG] =
  68         "^real_mode_seg$",
  69
  70 /*
  71  * These are offsets belonging to segments, as opposed to linear addresses,
  72  * when compiling 16-bit code.
  73  */
  74         [S_LIN] =
  75         "^pa_",
  76 };
  77
  78 static const char * const *sym_regex;
  79
  80 static regex_t sym_regex_c[S_NSYMTYPES];
  81 static int is_reloc(enum symtype type, const char *sym_name)
  82 {
  83         return sym_regex[type] &&
  84                 !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
  85 }
  86
  87 static void regex_init(int use_real_mode)
  88 {
  89         char errbuf[128];
  90         int err;
  91         int i;
  92
  93         if (use_real_mode)
  94                 sym_regex = sym_regex_realmode;
  95         else
  96                 sym_regex = sym_regex_kernel;
  97
  98         for (i = 0; i < S_NSYMTYPES; i++) {
  99                 if (!sym_regex[i])
 100                         continue;
 101
 102                 err = regcomp(&sym_regex_c[i], sym_regex[i],
 103                               REG_EXTENDED|REG_NOSUB);
 104
 105                 if (err) {
 106                         regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
 107                         die("%s", errbuf);
 108                 }
 109         }
 110 }
 111
 112 static void die(char *fmt, ...)
 113 {
 114         va_list ap;
 115         va_start(ap, fmt);
 116         vfprintf(stderr, fmt, ap);
 117         va_end(ap);
 118         exit(1);
 119 }
 120
 121 static const char *sym_type(unsigned type)
 122 {
 123         static const char *type_name[] = {
 124 #define SYM_TYPE(X) [X] = #X
 125                 SYM_TYPE(STT_NOTYPE),
 126                 SYM_TYPE(STT_OBJECT),
 127                 SYM_TYPE(STT_FUNC),
 128                 SYM_TYPE(STT_SECTION),
 129                 SYM_TYPE(STT_FILE),
 130                 SYM_TYPE(STT_COMMON),
 131                 SYM_TYPE(STT_TLS),
 132 #undef SYM_TYPE
 133         };
 134         const char *name = "unknown sym type name";
 135         if (type < ARRAY_SIZE(type_name)) {
 136                 name = type_name[type];
 137         }
 138         return name;
 139 }
 140
 141 static const char *sym_bind(unsigned bind)
 142 {
 143         static const char *bind_name[] = {
 144 #define SYM_BIND(X) [X] = #X
 145                 SYM_BIND(STB_LOCAL),
 146                 SYM_BIND(STB_GLOBAL),
 147                 SYM_BIND(STB_WEAK),
 148 #undef SYM_BIND
 149         };
 150         const char *name = "unknown sym bind name";
 151         if (bind < ARRAY_SIZE(bind_name)) {
 152                 name = bind_name[bind];
 153         }
 154         return name;
 155 }
 156
 157 static const char *sym_visibility(unsigned visibility)
 158 {
 159         static const char *visibility_name[] = {
 160 #define SYM_VISIBILITY(X) [X] = #X
 161                 SYM_VISIBILITY(STV_DEFAULT),
 162                 SYM_VISIBILITY(STV_INTERNAL),
 163                 SYM_VISIBILITY(STV_HIDDEN),
 164                 SYM_VISIBILITY(STV_PROTECTED),
 165 #undef SYM_VISIBILITY
 166         };
 167         const char *name = "unknown sym visibility name";
 168         if (visibility < ARRAY_SIZE(visibility_name)) {
 169                 name = visibility_name[visibility];
 170         }
 171         return name;
 172 }
 173
 174 static const char *rel_type(unsigned type)
 175 {
 176         static const char *type_name[] = {
 177 #define REL_TYPE(X) [X] = #X
 178                 REL_TYPE(R_386_NONE),
 179                 REL_TYPE(R_386_32),
 180                 REL_TYPE(R_386_PC32),
 181                 REL_TYPE(R_386_GOT32),
 182                 REL_TYPE(R_386_PLT32),
 183                 REL_TYPE(R_386_COPY),
 184                 REL_TYPE(R_386_GLOB_DAT),
 185                 REL_TYPE(R_386_JMP_SLOT),
 186                 REL_TYPE(R_386_RELATIVE),
 187                 REL_TYPE(R_386_GOTOFF),
 188                 REL_TYPE(R_386_GOTPC),
 189                 REL_TYPE(R_386_8),
 190                 REL_TYPE(R_386_PC8),
 191                 REL_TYPE(R_386_16),
 192                 REL_TYPE(R_386_PC16),
 193 #undef REL_TYPE
 194         };
 195         const char *name = "unknown type rel type name";
 196         if (type < ARRAY_SIZE(type_name) && type_name[type]) {
 197                 name = type_name[type];
 198         }
 199         return name;
 200 }
 201
 202 static const char *sec_name(unsigned shndx)
 203 {
 204         const char *sec_strtab;
 205         const char *name;
 206         sec_strtab = secs[ehdr.e_shstrndx].strtab;
 207         name = "<noname>";
 208         if (shndx < ehdr.e_shnum) {
 209                 name = sec_strtab + secs[shndx].shdr.sh_name;
 210         }
 211         else if (shndx == SHN_ABS) {
 212                 name = "ABSOLUTE";
 213         }
 214         else if (shndx == SHN_COMMON) {
 215                 name = "COMMON";
 216         }
 217         return name;
 218 }
 219
 220 static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
 221 {
 222         const char *name;
 223         name = "<noname>";
 224         if (sym->st_name) {
 225                 name = sym_strtab + sym->st_name;
 226         }
 227         else {
 228                 name = sec_name(sym->st_shndx);
 229         }
 230         return name;
 231 }
 232
 233
 234
 235 #if BYTE_ORDER == LITTLE_ENDIAN
 236 #define le16_to_cpu(val) (val)
 237 #define le32_to_cpu(val) (val)
 238 #endif
 239 #if BYTE_ORDER == BIG_ENDIAN
 240 #define le16_to_cpu(val) bswap_16(val)
 241 #define le32_to_cpu(val) bswap_32(val)
 242 #endif
 243
 244 static uint16_t elf16_to_cpu(uint16_t val)
 245 {
 246         return le16_to_cpu(val);
 247 }
 248
 249 static uint32_t elf32_to_cpu(uint32_t val)
 250 {
 251         return le32_to_cpu(val);
 252 }
 253
 254 static void read_ehdr(FILE *fp)
 255 {
 256         if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
 257                 die("Cannot read ELF header: %s\n",
 258                         strerror(errno));
 259         }
 260         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
 261                 die("No ELF magic\n");
 262         }
 263         if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
 264                 die("Not a 32 bit executable\n");
 265         }
 266         if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
 267                 die("Not a LSB ELF executable\n");
 268         }
 269         if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
 270                 die("Unknown ELF version\n");
 271         }
 272         /* Convert the fields to native endian */
 273         ehdr.e_type      = elf16_to_cpu(ehdr.e_type);
 274         ehdr.e_machine   = elf16_to_cpu(ehdr.e_machine);
 275         ehdr.e_version   = elf32_to_cpu(ehdr.e_version);
 276         ehdr.e_entry     = elf32_to_cpu(ehdr.e_entry);
 277         ehdr.e_phoff     = elf32_to_cpu(ehdr.e_phoff);
 278         ehdr.e_shoff     = elf32_to_cpu(ehdr.e_shoff);
 279         ehdr.e_flags     = elf32_to_cpu(ehdr.e_flags);
 280         ehdr.e_ehsize    = elf16_to_cpu(ehdr.e_ehsize);
 281         ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
 282         ehdr.e_phnum     = elf16_to_cpu(ehdr.e_phnum);
 283         ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
 284         ehdr.e_shnum     = elf16_to_cpu(ehdr.e_shnum);
 285         ehdr.e_shstrndx  = elf16_to_cpu(ehdr.e_shstrndx);
 286
 287         if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
 288                 die("Unsupported ELF header type\n");
 289         }
 290         if (ehdr.e_machine != EM_386) {
 291                 die("Not for x86\n");
 292         }
 293         if (ehdr.e_version != EV_CURRENT) {
 294                 die("Unknown ELF version\n");
 295         }
 296         if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
 297                 die("Bad Elf header size\n");
 298         }
 299         if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
 300                 die("Bad program header entry\n");
 301         }
 302         if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
 303                 die("Bad section header entry\n");
 304         }
 305         if (ehdr.e_shstrndx >= ehdr.e_shnum) {
 306                 die("String table index out of bounds\n");
 307         }
 308 }
 309
 310 static void read_shdrs(FILE *fp)
 311 {
 312         int i;
 313         Elf32_Shdr shdr;
 314
 315         secs = calloc(ehdr.e_shnum, sizeof(struct section));
 316         if (!secs) {
 317                 die("Unable to allocate %d section headers\n",
 318                     ehdr.e_shnum);
 319         }
 320         if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
 321                 die("Seek to %d failed: %s\n",
 322                         ehdr.e_shoff, strerror(errno));
 323         }
 324         for (i = 0; i < ehdr.e_shnum; i++) {
 325                 struct section *sec = &secs[i];
 326                 if (fread(&shdr, sizeof shdr, 1, fp) != 1)
 327                         die("Cannot read ELF section headers %d/%d: %s\n",
 328                             i, ehdr.e_shnum, strerror(errno));
 329                 sec->shdr.sh_name      = elf32_to_cpu(shdr.sh_name);
 330                 sec->shdr.sh_type      = elf32_to_cpu(shdr.sh_type);
 331                 sec->shdr.sh_flags     = elf32_to_cpu(shdr.sh_flags);
 332                 sec->shdr.sh_addr      = elf32_to_cpu(shdr.sh_addr);
 333                 sec->shdr.sh_offset    = elf32_to_cpu(shdr.sh_offset);
 334                 sec->shdr.sh_size      = elf32_to_cpu(shdr.sh_size);
 335                 sec->shdr.sh_link      = elf32_to_cpu(shdr.sh_link);
 336                 sec->shdr.sh_info      = elf32_to_cpu(shdr.sh_info);
 337                 sec->shdr.sh_addralign = elf32_to_cpu(shdr.sh_addralign);
 338                 sec->shdr.sh_entsize   = elf32_to_cpu(shdr.sh_entsize);
 339                 if (sec->shdr.sh_link < ehdr.e_shnum)
 340                         sec->link = &secs[sec->shdr.sh_link];
 341         }
 342
 343 }
 344
 345 static void read_strtabs(FILE *fp)
 346 {
 347         int i;
 348         for (i = 0; i < ehdr.e_shnum; i++) {
 349                 struct section *sec = &secs[i];
 350                 if (sec->shdr.sh_type != SHT_STRTAB) {
 351                         continue;
 352                 }
 353                 sec->strtab = malloc(sec->shdr.sh_size);
 354                 if (!sec->strtab) {
 355                         die("malloc of %d bytes for strtab failed\n",
 356                                 sec->shdr.sh_size);
 357                 }
 358                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 359                         die("Seek to %d failed: %s\n",
 360                                 sec->shdr.sh_offset, strerror(errno));
 361                 }
 362                 if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
 363                     != sec->shdr.sh_size) {
 364                         die("Cannot read symbol table: %s\n",
 365                                 strerror(errno));
 366                 }
 367         }
 368 }
 369
 370 static void read_symtabs(FILE *fp)
 371 {
 372         int i,j;
 373         for (i = 0; i < ehdr.e_shnum; i++) {
 374                 struct section *sec = &secs[i];
 375                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 376                         continue;
 377                 }
 378                 sec->symtab = malloc(sec->shdr.sh_size);
 379                 if (!sec->symtab) {
 380                         die("malloc of %d bytes for symtab failed\n",
 381                                 sec->shdr.sh_size);
 382                 }
 383                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 384                         die("Seek to %d failed: %s\n",
 385                                 sec->shdr.sh_offset, strerror(errno));
 386                 }
 387                 if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
 388                     != sec->shdr.sh_size) {
 389                         die("Cannot read symbol table: %s\n",
 390                                 strerror(errno));
 391                 }
 392                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
 393                         Elf32_Sym *sym = &sec->symtab[j];
 394                         sym->st_name  = elf32_to_cpu(sym->st_name);
 395                         sym->st_value = elf32_to_cpu(sym->st_value);
 396                         sym->st_size  = elf32_to_cpu(sym->st_size);
 397                         sym->st_shndx = elf16_to_cpu(sym->st_shndx);
 398                 }
 399         }
 400 }
 401
 402
 403 static void read_relocs(FILE *fp)
 404 {
 405         int i,j;
 406         for (i = 0; i < ehdr.e_shnum; i++) {
 407                 struct section *sec = &secs[i];
 408                 if (sec->shdr.sh_type != SHT_REL) {
 409                         continue;
 410                 }
 411                 sec->reltab = malloc(sec->shdr.sh_size);
 412                 if (!sec->reltab) {
 413                         die("malloc of %d bytes for relocs failed\n",
 414                                 sec->shdr.sh_size);
 415                 }
 416                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 417                         die("Seek to %d failed: %s\n",
 418                                 sec->shdr.sh_offset, strerror(errno));
 419                 }
 420                 if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
 421                     != sec->shdr.sh_size) {
 422                         die("Cannot read symbol table: %s\n",
 423                                 strerror(errno));
 424                 }
 425                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
 426                         Elf32_Rel *rel = &sec->reltab[j];
 427                         rel->r_offset = elf32_to_cpu(rel->r_offset);
 428                         rel->r_info   = elf32_to_cpu(rel->r_info);
 429                 }
 430         }
 431 }
 432
 433
 434 static void print_absolute_symbols(void)
 435 {
 436         int i;
 437         printf("Absolute symbols\n");
 438         printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
 439         for (i = 0; i < ehdr.e_shnum; i++) {
 440                 struct section *sec = &secs[i];
 441                 char *sym_strtab;
 442                 int j;
 443
 444                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 445                         continue;
 446                 }
 447                 sym_strtab = sec->link->strtab;
 448                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
 449                         Elf32_Sym *sym;
 450                         const char *name;
 451                         sym = &sec->symtab[j];
 452                         name = sym_name(sym_strtab, sym);
 453                         if (sym->st_shndx != SHN_ABS) {
 454                                 continue;
 455                         }
 456                         printf("%5d %08x %5d %10s %10s %12s %s\n",
 457                                 j, sym->st_value, sym->st_size,
 458                                 sym_type(ELF32_ST_TYPE(sym->st_info)),
 459                                 sym_bind(ELF32_ST_BIND(sym->st_info)),
 460                                 sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
 461                                 name);
 462                 }
 463         }
 464         printf("\n");
 465 }
 466
 467 static void print_absolute_relocs(void)
 468 {
 469         int i, printed = 0;
 470
 471         for (i = 0; i < ehdr.e_shnum; i++) {
 472                 struct section *sec = &secs[i];
 473                 struct section *sec_applies, *sec_symtab;
 474                 char *sym_strtab;
 475                 Elf32_Sym *sh_symtab;
 476                 int j;
 477                 if (sec->shdr.sh_type != SHT_REL) {
 478                         continue;
 479                 }
 480                 sec_symtab  = sec->link;
 481                 sec_applies = &secs[sec->shdr.sh_info];
 482                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 483                         continue;
 484                 }
 485                 sh_symtab  = sec_symtab->symtab;
 486                 sym_strtab = sec_symtab->link->strtab;
 487                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
 488                         Elf32_Rel *rel;
 489                         Elf32_Sym *sym;
 490                         const char *name;
 491                         rel = &sec->reltab[j];
 492                         sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
 493                         name = sym_name(sym_strtab, sym);
 494                         if (sym->st_shndx != SHN_ABS) {
 495                                 continue;
 496                         }
 497
 498                         /* Absolute symbols are not relocated if bzImage is
 499                          * loaded at a non-compiled address. Display a warning
 500                          * to user at compile time about the absolute
 501                          * relocations present.
 502                          *
 503                          * User need to audit the code to make sure
 504                          * some symbols which should have been section
 505                          * relative have not become absolute because of some
 506                          * linker optimization or wrong programming usage.
 507                          *
 508                          * Before warning check if this absolute symbol
 509                          * relocation is harmless.
 510                          */
 511                         if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
 512                                 continue;
 513
 514                         if (!printed) {
 515                                 printf("WARNING: Absolute relocations"
 516                                         " present\n");
 517                                 printf("Offset     Info     Type     Sym.Value "
 518                                         "Sym.Name\n");
 519                                 printed = 1;
 520                         }
 521
 522                         printf("%08x %08x %10s %08x  %s\n",
 523                                 rel->r_offset,
 524                                 rel->r_info,
 525                                 rel_type(ELF32_R_TYPE(rel->r_info)),
 526                                 sym->st_value,
 527                                 name);
 528                 }
 529         }
 530
 531         if (printed)
 532                 printf("\n");
 533 }
 534
 535 static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym),
 536                         int use_real_mode)
 537 {
 538         int i;
 539         /* Walk through the relocations */
 540         for (i = 0; i < ehdr.e_shnum; i++) {
 541                 char *sym_strtab;
 542                 Elf32_Sym *sh_symtab;
 543                 struct section *sec_applies, *sec_symtab;
 544                 int j;
 545                 struct section *sec = &secs[i];
 546
 547                 if (sec->shdr.sh_type != SHT_REL) {
 548                         continue;
 549                 }
 550                 sec_symtab  = sec->link;
 551                 sec_applies = &secs[sec->shdr.sh_info];
 552                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 553                         continue;
 554                 }
 555                 sh_symtab = sec_symtab->symtab;
 556                 sym_strtab = sec_symtab->link->strtab;
 557                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
 558                         Elf32_Rel *rel;
 559                         Elf32_Sym *sym;
 560                         unsigned r_type;
 561                         const char *symname;
 562                         rel = &sec->reltab[j];
 563                         sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
 564                         r_type = ELF32_R_TYPE(rel->r_info);
 565
 566                         switch (r_type) {
 567                         case R_386_NONE:
 568                         case R_386_PC32:
 569                         case R_386_PC16:
 570                         case R_386_PC8:
 571                                 /*
 572                                  * NONE can be ignored and and PC relative
 573                                  * relocations don't need to be adjusted.
 574                                  */
 575                                 break;
 576
 577                         case R_386_16:
 578                                 symname = sym_name(sym_strtab, sym);
 579                                 if (!use_real_mode)
 580                                         goto bad;
 581                                 if (sym->st_shndx == SHN_ABS) {
 582                                         if (is_reloc(S_ABS, symname))
 583                                                 break;
 584                                         else if (!is_reloc(S_SEG, symname))
 585                                                 goto bad;
 586                                 } else {
 587                                         if (is_reloc(S_LIN, symname))
 588                                                 goto bad;
 589                                         else
 590                                                 break;
 591                                 }
 592                                 visit(rel, sym);
 593                                 break;
 594
 595                         case R_386_32:
 596                                 symname = sym_name(sym_strtab, sym);
 597                                 if (sym->st_shndx == SHN_ABS) {
 598                                         if (is_reloc(S_ABS, symname))
 599                                                 break;
 600                                         else if (!is_reloc(S_REL, symname))
 601                                                 goto bad;
 602                                 } else {
 603                                         if (use_real_mode &&
 604                                             !is_reloc(S_LIN, symname))
 605                                                 break;
 606                                 }
 607                                 visit(rel, sym);
 608                                 break;
 609                         default:
 610                                 die("Unsupported relocation type: %s (%d)\n",
 611                                     rel_type(r_type), r_type);
 612                                 break;
 613                         bad:
 614                                 symname = sym_name(sym_strtab, sym);
 615                                 die("Invalid %s relocation: %s\n",
 616                                     rel_type(r_type), symname);
 617                         }
 618                 }
 619         }
 620 }
 621
 622 static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
 623 {
 624         if (ELF32_R_TYPE(rel->r_info) == R_386_16)
 625                 reloc16_count++;
 626         else
 627                 reloc_count++;
 628 }
 629
 630 static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
 631 {
 632         /* Remember the address that needs to be adjusted. */
 633         if (ELF32_R_TYPE(rel->r_info) == R_386_16)
 634                 relocs16[reloc16_idx++] = rel->r_offset;
 635         else
 636                 relocs[reloc_idx++] = rel->r_offset;
 637 }
 638
 639 static int cmp_relocs(const void *va, const void *vb)
 640 {
 641         const unsigned long *a, *b;
 642         a = va; b = vb;
 643         return (*a == *b)? 0 : (*a > *b)? 1 : -1;
 644 }
 645
 646 static int write32(unsigned int v, FILE *f)
 647 {
 648         unsigned char buf[4];
 649
 650         put_unaligned_le32(v, buf);
 651         return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
 652 }
 653
 654 static void emit_relocs(int as_text, int use_real_mode)
 655 {
 656         int i;
 657         /* Count how many relocations I have and allocate space for them. */
 658         reloc_count = 0;
 659         walk_relocs(count_reloc, use_real_mode);
 660         relocs = malloc(reloc_count * sizeof(relocs[0]));
 661         if (!relocs) {
 662                 die("malloc of %d entries for relocs failed\n",
 663                         reloc_count);
 664         }
 665
 666         relocs16 = malloc(reloc16_count * sizeof(relocs[0]));
 667         if (!relocs16) {
 668                 die("malloc of %d entries for relocs16 failed\n",
 669                         reloc16_count);
 670         }
 671         /* Collect up the relocations */
 672         reloc_idx = 0;
 673         walk_relocs(collect_reloc, use_real_mode);
 674
 675         if (reloc16_count && !use_real_mode)
 676                 die("Segment relocations found but --realmode not specified\n");
 677
 678         /* Order the relocations for more efficient processing */
 679         qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
 680         qsort(relocs16, reloc16_count, sizeof(relocs16[0]), cmp_relocs);
 681
 682         /* Print the relocations */
 683         if (as_text) {
 684                 /* Print the relocations in a form suitable that
 685                  * gas will like.
 686                  */
 687                 printf(".section \".data.reloc\",\"a\"\n");
 688                 printf(".balign 4\n");
 689                 if (use_real_mode) {
 690                         printf("\t.long %lu\n", reloc16_count);
 691                         for (i = 0; i < reloc16_count; i++)
 692                                 printf("\t.long 0x%08lx\n", relocs16[i]);
 693                         printf("\t.long %lu\n", reloc_count);
 694                         for (i = 0; i < reloc_count; i++) {
 695                                 printf("\t.long 0x%08lx\n", relocs[i]);
 696                         }
 697                 } else {
 698                         /* Print a stop */
 699                         printf("\t.long 0x%08lx\n", (unsigned long)0);
 700                         for (i = 0; i < reloc_count; i++) {
 701                                 printf("\t.long 0x%08lx\n", relocs[i]);
 702                         }
 703                 }
 704
 705                 printf("\n");
 706         }
 707         else {
 708                 if (use_real_mode) {
 709                         write32(reloc16_count, stdout);
 710                         for (i = 0; i < reloc16_count; i++)
 711                                 write32(relocs16[i], stdout);
 712                         write32(reloc_count, stdout);
 713
 714                         /* Now print each relocation */
 715                         for (i = 0; i < reloc_count; i++)
 716                                 write32(relocs[i], stdout);
 717                 } else {
 718                         /* Print a stop */
 719                         write32(0, stdout);
 720
 721                         /* Now print each relocation */
 722                         for (i = 0; i < reloc_count; i++) {
 723                                 write32(relocs[i], stdout);
 724                         }
 725                 }
 726         }
 727 }
 728
 729 static void usage(void)
 730 {
 731         die("relocs [--abs-syms|--abs-relocs|--text|--realmode] vmlinux\n");
 732 }
 733
 734 int main(int argc, char **argv)
 735 {
 736         int show_absolute_syms, show_absolute_relocs;
 737         int as_text, use_real_mode;
 738         const char *fname;
 739         FILE *fp;
 740         int i;
 741
 742         show_absolute_syms = 0;
 743         show_absolute_relocs = 0;
 744         as_text = 0;
 745         use_real_mode = 0;
 746         fname = NULL;
 747         for (i = 1; i < argc; i++) {
 748                 char *arg = argv[i];
 749                 if (*arg == '-') {
 750                         if (strcmp(arg, "--abs-syms") == 0) {
 751                                 show_absolute_syms = 1;
 752                                 continue;
 753                         }
 754                         if (strcmp(arg, "--abs-relocs") == 0) {
 755                                 show_absolute_relocs = 1;
 756                                 continue;
 757                         }
 758                         if (strcmp(arg, "--text") == 0) {
 759                                 as_text = 1;
 760                                 continue;
 761                         }
 762                         if (strcmp(arg, "--realmode") == 0) {
 763                                 use_real_mode = 1;
 764                                 continue;
 765                         }
 766                 }
 767                 else if (!fname) {
 768                         fname = arg;
 769                         continue;
 770                 }
 771                 usage();
 772         }
 773         if (!fname) {
 774                 usage();
 775         }
 776         regex_init(use_real_mode);
 777         fp = fopen(fname, "r");
 778         if (!fp) {
 779                 die("Cannot open %s: %s\n",
 780                         fname, strerror(errno));
 781         }
 782         read_ehdr(fp);
 783         read_shdrs(fp);
 784         read_strtabs(fp);
 785         read_symtabs(fp);
 786         read_relocs(fp);
 787         if (show_absolute_syms) {
 788                 print_absolute_symbols();
 789                 return 0;
 790         }
 791         if (show_absolute_relocs) {
 792                 print_absolute_relocs();
 793                 return 0;
 794         }
 795         emit_relocs(as_text, use_real_mode);
 796         return 0;
 797 }