arch/i386/boot/compressed/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
  13 #define MAX_SHDRS 100
  14 static Elf32_Ehdr ehdr;
  15 static Elf32_Shdr shdr[MAX_SHDRS];
  16 static Elf32_Sym  *symtab[MAX_SHDRS];
  17 static Elf32_Rel  *reltab[MAX_SHDRS];
  18 static char *strtab[MAX_SHDRS];
  19 static unsigned long reloc_count, reloc_idx;
  20 static unsigned long *relocs;
  21
  22 static void die(char *fmt, ...)
  23 {
  24         va_list ap;
  25         va_start(ap, fmt);
  26         vfprintf(stderr, fmt, ap);
  27         va_end(ap);
  28         exit(1);
  29 }
  30
  31 static const char *sym_type(unsigned type)
  32 {
  33         static const char *type_name[] = {
  34 #define SYM_TYPE(X) [X] = #X
  35                 SYM_TYPE(STT_NOTYPE),
  36                 SYM_TYPE(STT_OBJECT),
  37                 SYM_TYPE(STT_FUNC),
  38                 SYM_TYPE(STT_SECTION),
  39                 SYM_TYPE(STT_FILE),
  40                 SYM_TYPE(STT_COMMON),
  41                 SYM_TYPE(STT_TLS),
  42 #undef SYM_TYPE
  43         };
  44         const char *name = "unknown sym type name";
  45         if (type < sizeof(type_name)/sizeof(type_name[0])) {
  46                 name = type_name[type];
  47         }
  48         return name;
  49 }
  50
  51 static const char *sym_bind(unsigned bind)
  52 {
  53         static const char *bind_name[] = {
  54 #define SYM_BIND(X) [X] = #X
  55                 SYM_BIND(STB_LOCAL),
  56                 SYM_BIND(STB_GLOBAL),
  57                 SYM_BIND(STB_WEAK),
  58 #undef SYM_BIND
  59         };
  60         const char *name = "unknown sym bind name";
  61         if (bind < sizeof(bind_name)/sizeof(bind_name[0])) {
  62                 name = bind_name[bind];
  63         }
  64         return name;
  65 }
  66
  67 static const char *sym_visibility(unsigned visibility)
  68 {
  69         static const char *visibility_name[] = {
  70 #define SYM_VISIBILITY(X) [X] = #X
  71                 SYM_VISIBILITY(STV_DEFAULT),
  72                 SYM_VISIBILITY(STV_INTERNAL),
  73                 SYM_VISIBILITY(STV_HIDDEN),
  74                 SYM_VISIBILITY(STV_PROTECTED),
  75 #undef SYM_VISIBILITY
  76         };
  77         const char *name = "unknown sym visibility name";
  78         if (visibility < sizeof(visibility_name)/sizeof(visibility_name[0])) {
  79                 name = visibility_name[visibility];
  80         }
  81         return name;
  82 }
  83
  84 static const char *rel_type(unsigned type)
  85 {
  86         static const char *type_name[] = {
  87 #define REL_TYPE(X) [X] = #X
  88                 REL_TYPE(R_386_NONE),
  89                 REL_TYPE(R_386_32),
  90                 REL_TYPE(R_386_PC32),
  91                 REL_TYPE(R_386_GOT32),
  92                 REL_TYPE(R_386_PLT32),
  93                 REL_TYPE(R_386_COPY),
  94                 REL_TYPE(R_386_GLOB_DAT),
  95                 REL_TYPE(R_386_JMP_SLOT),
  96                 REL_TYPE(R_386_RELATIVE),
  97                 REL_TYPE(R_386_GOTOFF),
  98                 REL_TYPE(R_386_GOTPC),
  99 #undef REL_TYPE
 100         };
 101         const char *name = "unknown type rel type name";
 102         if (type < sizeof(type_name)/sizeof(type_name[0])) {
 103                 name = type_name[type];
 104         }
 105         return name;
 106 }
 107
 108 static const char *sec_name(unsigned shndx)
 109 {
 110         const char *sec_strtab;
 111         const char *name;
 112         sec_strtab = strtab[ehdr.e_shstrndx];
 113         name = "<noname>";
 114         if (shndx < ehdr.e_shnum) {
 115                 name = sec_strtab + shdr[shndx].sh_name;
 116         }
 117         else if (shndx == SHN_ABS) {
 118                 name = "ABSOLUTE";
 119         }
 120         else if (shndx == SHN_COMMON) {
 121                 name = "COMMON";
 122         }
 123         return name;
 124 }
 125
 126 static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
 127 {
 128         const char *name;
 129         name = "<noname>";
 130         if (sym->st_name) {
 131                 name = sym_strtab + sym->st_name;
 132         }
 133         else {
 134                 name = sec_name(shdr[sym->st_shndx].sh_name);
 135         }
 136         return name;
 137 }
 138
 139
 140
 141 #if BYTE_ORDER == LITTLE_ENDIAN
 142 #define le16_to_cpu(val) (val)
 143 #define le32_to_cpu(val) (val)
 144 #endif
 145 #if BYTE_ORDER == BIG_ENDIAN
 146 #define le16_to_cpu(val) bswap_16(val)
 147 #define le32_to_cpu(val) bswap_32(val)
 148 #endif
 149
 150 static uint16_t elf16_to_cpu(uint16_t val)
 151 {
 152         return le16_to_cpu(val);
 153 }
 154
 155 static uint32_t elf32_to_cpu(uint32_t val)
 156 {
 157         return le32_to_cpu(val);
 158 }
 159
 160 static void read_ehdr(FILE *fp)
 161 {
 162         if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
 163                 die("Cannot read ELF header: %s\n",
 164                         strerror(errno));
 165         }
 166         if (memcmp(ehdr.e_ident, ELFMAG, 4) != 0) {
 167                 die("No ELF magic\n");
 168         }
 169         if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
 170                 die("Not a 32 bit executable\n");
 171         }
 172         if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
 173                 die("Not a LSB ELF executable\n");
 174         }
 175         if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
 176                 die("Unknown ELF version\n");
 177         }
 178         /* Convert the fields to native endian */
 179         ehdr.e_type      = elf16_to_cpu(ehdr.e_type);
 180         ehdr.e_machine   = elf16_to_cpu(ehdr.e_machine);
 181         ehdr.e_version   = elf32_to_cpu(ehdr.e_version);
 182         ehdr.e_entry     = elf32_to_cpu(ehdr.e_entry);
 183         ehdr.e_phoff     = elf32_to_cpu(ehdr.e_phoff);
 184         ehdr.e_shoff     = elf32_to_cpu(ehdr.e_shoff);
 185         ehdr.e_flags     = elf32_to_cpu(ehdr.e_flags);
 186         ehdr.e_ehsize    = elf16_to_cpu(ehdr.e_ehsize);
 187         ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
 188         ehdr.e_phnum     = elf16_to_cpu(ehdr.e_phnum);
 189         ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
 190         ehdr.e_shnum     = elf16_to_cpu(ehdr.e_shnum);
 191         ehdr.e_shstrndx  = elf16_to_cpu(ehdr.e_shstrndx);
 192
 193         if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
 194                 die("Unsupported ELF header type\n");
 195         }
 196         if (ehdr.e_machine != EM_386) {
 197                 die("Not for x86\n");
 198         }
 199         if (ehdr.e_version != EV_CURRENT) {
 200                 die("Unknown ELF version\n");
 201         }
 202         if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
 203                 die("Bad Elf header size\n");
 204         }
 205         if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
 206                 die("Bad program header entry\n");
 207         }
 208         if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
 209                 die("Bad section header entry\n");
 210         }
 211         if (ehdr.e_shstrndx >= ehdr.e_shnum) {
 212                 die("String table index out of bounds\n");
 213         }
 214 }
 215
 216 static void read_shdrs(FILE *fp)
 217 {
 218         int i;
 219         if (ehdr.e_shnum > MAX_SHDRS) {
 220                 die("%d section headers supported: %d\n",
 221                         ehdr.e_shnum, MAX_SHDRS);
 222         }
 223         if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
 224                 die("Seek to %d failed: %s\n",
 225                         ehdr.e_shoff, strerror(errno));
 226         }
 227         if (fread(&shdr, sizeof(shdr[0]), ehdr.e_shnum, fp) != ehdr.e_shnum) {
 228                 die("Cannot read ELF section headers: %s\n",
 229                         strerror(errno));
 230         }
 231         for(i = 0; i < ehdr.e_shnum; i++) {
 232                 shdr[i].sh_name      = elf32_to_cpu(shdr[i].sh_name);
 233                 shdr[i].sh_type      = elf32_to_cpu(shdr[i].sh_type);
 234                 shdr[i].sh_flags     = elf32_to_cpu(shdr[i].sh_flags);
 235                 shdr[i].sh_addr      = elf32_to_cpu(shdr[i].sh_addr);
 236                 shdr[i].sh_offset    = elf32_to_cpu(shdr[i].sh_offset);
 237                 shdr[i].sh_size      = elf32_to_cpu(shdr[i].sh_size);
 238                 shdr[i].sh_link      = elf32_to_cpu(shdr[i].sh_link);
 239                 shdr[i].sh_info      = elf32_to_cpu(shdr[i].sh_info);
 240                 shdr[i].sh_addralign = elf32_to_cpu(shdr[i].sh_addralign);
 241                 shdr[i].sh_entsize   = elf32_to_cpu(shdr[i].sh_entsize);
 242         }
 243
 244 }
 245
 246 static void read_strtabs(FILE *fp)
 247 {
 248         int i;
 249         for(i = 0; i < ehdr.e_shnum; i++) {
 250                 if (shdr[i].sh_type != SHT_STRTAB) {
 251                         continue;
 252                 }
 253                 strtab[i] = malloc(shdr[i].sh_size);
 254                 if (!strtab[i]) {
 255                         die("malloc of %d bytes for strtab failed\n",
 256                                 shdr[i].sh_size);
 257                 }
 258                 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
 259                         die("Seek to %d failed: %s\n",
 260                                 shdr[i].sh_offset, strerror(errno));
 261                 }
 262                 if (fread(strtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
 263                         die("Cannot read symbol table: %s\n",
 264                                 strerror(errno));
 265                 }
 266         }
 267 }
 268
 269 static void read_symtabs(FILE *fp)
 270 {
 271         int i,j;
 272         for(i = 0; i < ehdr.e_shnum; i++) {
 273                 if (shdr[i].sh_type != SHT_SYMTAB) {
 274                         continue;
 275                 }
 276                 symtab[i] = malloc(shdr[i].sh_size);
 277                 if (!symtab[i]) {
 278                         die("malloc of %d bytes for symtab failed\n",
 279                                 shdr[i].sh_size);
 280                 }
 281                 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
 282                         die("Seek to %d failed: %s\n",
 283                                 shdr[i].sh_offset, strerror(errno));
 284                 }
 285                 if (fread(symtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
 286                         die("Cannot read symbol table: %s\n",
 287                                 strerror(errno));
 288                 }
 289                 for(j = 0; j < shdr[i].sh_size/sizeof(symtab[i][0]); j++) {
 290                         symtab[i][j].st_name  = elf32_to_cpu(symtab[i][j].st_name);
 291                         symtab[i][j].st_value = elf32_to_cpu(symtab[i][j].st_value);
 292                         symtab[i][j].st_size  = elf32_to_cpu(symtab[i][j].st_size);
 293                         symtab[i][j].st_shndx = elf16_to_cpu(symtab[i][j].st_shndx);
 294                 }
 295         }
 296 }
 297
 298
 299 static void read_relocs(FILE *fp)
 300 {
 301         int i,j;
 302         for(i = 0; i < ehdr.e_shnum; i++) {
 303                 if (shdr[i].sh_type != SHT_REL) {
 304                         continue;
 305                 }
 306                 reltab[i] = malloc(shdr[i].sh_size);
 307                 if (!reltab[i]) {
 308                         die("malloc of %d bytes for relocs failed\n",
 309                                 shdr[i].sh_size);
 310                 }
 311                 if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
 312                         die("Seek to %d failed: %s\n",
 313                                 shdr[i].sh_offset, strerror(errno));
 314                 }
 315                 if (fread(reltab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
 316                         die("Cannot read symbol table: %s\n",
 317                                 strerror(errno));
 318                 }
 319                 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
 320                         reltab[i][j].r_offset = elf32_to_cpu(reltab[i][j].r_offset);
 321                         reltab[i][j].r_info   = elf32_to_cpu(reltab[i][j].r_info);
 322                 }
 323         }
 324 }
 325
 326
 327 static void print_absolute_symbols(void)
 328 {
 329         int i;
 330         printf("Absolute symbols\n");
 331         printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
 332         for(i = 0; i < ehdr.e_shnum; i++) {
 333                 char *sym_strtab;
 334                 Elf32_Sym *sh_symtab;
 335                 int j;
 336                 if (shdr[i].sh_type != SHT_SYMTAB) {
 337                         continue;
 338                 }
 339                 sh_symtab = symtab[i];
 340                 sym_strtab = strtab[shdr[i].sh_link];
 341                 for(j = 0; j < shdr[i].sh_size/sizeof(symtab[0][0]); j++) {
 342                         Elf32_Sym *sym;
 343                         const char *name;
 344                         sym = &symtab[i][j];
 345                         name = sym_name(sym_strtab, sym);
 346                         if (sym->st_shndx != SHN_ABS) {
 347                                 continue;
 348                         }
 349                         printf("%5d %08x %5d %10s %10s %12s %s\n",
 350                                 j, sym->st_value, sym->st_size,
 351                                 sym_type(ELF32_ST_TYPE(sym->st_info)),
 352                                 sym_bind(ELF32_ST_BIND(sym->st_info)),
 353                                 sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
 354                                 name);
 355                 }
 356         }
 357         printf("\n");
 358 }
 359
 360 static void print_absolute_relocs(void)
 361 {
 362         int i;
 363         printf("Absolute relocations\n");
 364         printf("Offset     Info     Type     Sym.Value Sym.Name\n");
 365         for(i = 0; i < ehdr.e_shnum; i++) {
 366                 char *sym_strtab;
 367                 Elf32_Sym *sh_symtab;
 368                 unsigned sec_applies, sec_symtab;
 369                 int j;
 370                 if (shdr[i].sh_type != SHT_REL) {
 371                         continue;
 372                 }
 373                 sec_symtab  = shdr[i].sh_link;
 374                 sec_applies = shdr[i].sh_info;
 375                 if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
 376                         continue;
 377                 }
 378                 sh_symtab = symtab[sec_symtab];
 379                 sym_strtab = strtab[shdr[sec_symtab].sh_link];
 380                 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
 381                         Elf32_Rel *rel;
 382                         Elf32_Sym *sym;
 383                         const char *name;
 384                         rel = &reltab[i][j];
 385                         sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
 386                         name = sym_name(sym_strtab, sym);
 387                         if (sym->st_shndx != SHN_ABS) {
 388                                 continue;
 389                         }
 390                         printf("%08x %08x %10s %08x  %s\n",
 391                                 rel->r_offset,
 392                                 rel->r_info,
 393                                 rel_type(ELF32_R_TYPE(rel->r_info)),
 394                                 sym->st_value,
 395                                 name);
 396                 }
 397         }
 398         printf("\n");
 399 }
 400
 401 static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
 402 {
 403         int i;
 404         /* Walk through the relocations */
 405         for(i = 0; i < ehdr.e_shnum; i++) {
 406                 char *sym_strtab;
 407                 Elf32_Sym *sh_symtab;
 408                 unsigned sec_applies, sec_symtab;
 409                 int j;
 410                 if (shdr[i].sh_type != SHT_REL) {
 411                         continue;
 412                 }
 413                 sec_symtab  = shdr[i].sh_link;
 414                 sec_applies = shdr[i].sh_info;
 415                 if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
 416                         continue;
 417                 }
 418                 sh_symtab = symtab[sec_symtab];
 419                 sym_strtab = strtab[shdr[sec_symtab].sh_link];
 420                 for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
 421                         Elf32_Rel *rel;
 422                         Elf32_Sym *sym;
 423                         unsigned r_type;
 424                         rel = &reltab[i][j];
 425                         sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
 426                         r_type = ELF32_R_TYPE(rel->r_info);
 427                         /* Don't visit relocations to absolute symbols */
 428                         if (sym->st_shndx == SHN_ABS) {
 429                                 continue;
 430                         }
 431                         if (r_type == R_386_PC32) {
 432                                 /* PC relative relocations don't need to be adjusted */
 433                         }
 434                         else if (r_type == R_386_32) {
 435                                 /* Visit relocations that need to be adjusted */
 436                                 visit(rel, sym);
 437                         }
 438                         else {
 439                                 die("Unsupported relocation type: %d\n", r_type);
 440                         }
 441                 }
 442         }
 443 }
 444
 445 static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
 446 {
 447         reloc_count += 1;
 448 }
 449
 450 static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
 451 {
 452         /* Remember the address that needs to be adjusted. */
 453         relocs[reloc_idx++] = rel->r_offset;
 454 }
 455
 456 static int cmp_relocs(const void *va, const void *vb)
 457 {
 458         const unsigned long *a, *b;
 459         a = va; b = vb;
 460         return (*a == *b)? 0 : (*a > *b)? 1 : -1;
 461 }
 462
 463 static void emit_relocs(int as_text)
 464 {
 465         int i;
 466         /* Count how many relocations I have and allocate space for them. */
 467         reloc_count = 0;
 468         walk_relocs(count_reloc);
 469         relocs = malloc(reloc_count * sizeof(relocs[0]));
 470         if (!relocs) {
 471                 die("malloc of %d entries for relocs failed\n",
 472                         reloc_count);
 473         }
 474         /* Collect up the relocations */
 475         reloc_idx = 0;
 476         walk_relocs(collect_reloc);
 477
 478         /* Order the relocations for more efficient processing */
 479         qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
 480
 481         /* Print the relocations */
 482         if (as_text) {
 483                 /* Print the relocations in a form suitable that
 484                  * gas will like.
 485                  */
 486                 printf(".section \".data.reloc\",\"a\"\n");
 487                 printf(".balign 4\n");
 488                 for(i = 0; i < reloc_count; i++) {
 489                         printf("\t .long 0x%08lx\n", relocs[i]);
 490                 }
 491                 printf("\n");
 492         }
 493         else {
 494                 unsigned char buf[4];
 495                 buf[0] = buf[1] = buf[2] = buf[3] = 0;
 496                 /* Print a stop */
 497                 printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
 498                 /* Now print each relocation */
 499                 for(i = 0; i < reloc_count; i++) {
 500                         buf[0] = (relocs[i] >>  0) & 0xff;
 501                         buf[1] = (relocs[i] >>  8) & 0xff;
 502                         buf[2] = (relocs[i] >> 16) & 0xff;
 503                         buf[3] = (relocs[i] >> 24) & 0xff;
 504                         printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
 505                 }
 506         }
 507 }
 508
 509 static void usage(void)
 510 {
 511         die("i386_reloc [--abs | --text] vmlinux\n");
 512 }
 513
 514 int main(int argc, char **argv)
 515 {
 516         int show_absolute;
 517         int as_text;
 518         const char *fname;
 519         FILE *fp;
 520         int i;
 521
 522         show_absolute = 0;
 523         as_text = 0;
 524         fname = NULL;
 525         for(i = 1; i < argc; i++) {
 526                 char *arg = argv[i];
 527                 if (*arg == '-') {
 528                         if (strcmp(argv[1], "--abs") == 0) {
 529                                 show_absolute = 1;
 530                                 continue;
 531                         }
 532                         else if (strcmp(argv[1], "--text") == 0) {
 533                                 as_text = 1;
 534                                 continue;
 535                         }
 536                 }
 537                 else if (!fname) {
 538                         fname = arg;
 539                         continue;
 540                 }
 541                 usage();
 542         }
 543         if (!fname) {
 544                 usage();
 545         }
 546         fp = fopen(fname, "r");
 547         if (!fp) {
 548                 die("Cannot open %s: %s\n",
 549                         fname, strerror(errno));
 550         }
 551         read_ehdr(fp);
 552         read_shdrs(fp);
 553         read_strtabs(fp);
 554         read_symtabs(fp);
 555         read_relocs(fp);
 556         if (show_absolute) {
 557                 print_absolute_symbols();
 558                 print_absolute_relocs();
 559                 return 0;
 560         }
 561         emit_relocs(as_text);
 562         return 0;
 563 }