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         "^(__init_(begin|end)|"
  60         "__x86_cpu_dev_(start|end)|"
  61         "(__parainstructions|__alt_instructions)(|_end)|"
  62         "(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
  63         "__(start|end)_pci_.*|"
  64         "__(start|end)_builtin_fw|"
  65         "__(start|stop)___ksymtab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
  66         "__(start|stop)___kcrctab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
  67         "__(start|stop)___param|"
  68         "__(start|stop)___modver|"
  69         "__(start|stop)___bug_table|"
  70         "__tracedata_(start|end)|"
  71         "__(start|stop)_notes|"
  72         "__end_rodata|"
  73         "__initramfs_start|"
  74         "(jiffies|jiffies_64)|"
  75         "_end)$"
  76 };
  77
  78
  79 static const char * const sym_regex_realmode[S_NSYMTYPES] = {
  80 /*
  81  * These symbols are known to be relative, even if the linker marks them
  82  * as absolute (typically defined outside any section in the linker script.)
  83  */
  84         [S_REL] =
  85         "^pa_",
  86
  87 /*
  88  * These are 16-bit segment symbols when compiling 16-bit code.
  89  */
  90         [S_SEG] =
  91         "^real_mode_seg$",
  92
  93 /*
  94  * These are offsets belonging to segments, as opposed to linear addresses,
  95  * when compiling 16-bit code.
  96  */
  97         [S_LIN] =
  98         "^pa_",
  99 };
 100
 101 static const char * const *sym_regex;
 102
 103 static regex_t sym_regex_c[S_NSYMTYPES];
 104 static int is_reloc(enum symtype type, const char *sym_name)
 105 {
 106         return sym_regex[type] &&
 107                 !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
 108 }
 109
 110 static void regex_init(int use_real_mode)
 111 {
 112         char errbuf[128];
 113         int err;
 114         int i;
 115
 116         if (use_real_mode)
 117                 sym_regex = sym_regex_realmode;
 118         else
 119                 sym_regex = sym_regex_kernel;
 120
 121         for (i = 0; i < S_NSYMTYPES; i++) {
 122                 if (!sym_regex[i])
 123                         continue;
 124
 125                 err = regcomp(&sym_regex_c[i], sym_regex[i],
 126                               REG_EXTENDED|REG_NOSUB);
 127
 128                 if (err) {
 129                         regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
 130                         die("%s", errbuf);
 131                 }
 132         }
 133 }
 134
 135 static void die(char *fmt, ...)
 136 {
 137         va_list ap;
 138         va_start(ap, fmt);
 139         vfprintf(stderr, fmt, ap);
 140         va_end(ap);
 141         exit(1);
 142 }
 143
 144 static const char *sym_type(unsigned type)
 145 {
 146         static const char *type_name[] = {
 147 #define SYM_TYPE(X) [X] = #X
 148                 SYM_TYPE(STT_NOTYPE),
 149                 SYM_TYPE(STT_OBJECT),
 150                 SYM_TYPE(STT_FUNC),
 151                 SYM_TYPE(STT_SECTION),
 152                 SYM_TYPE(STT_FILE),
 153                 SYM_TYPE(STT_COMMON),
 154                 SYM_TYPE(STT_TLS),
 155 #undef SYM_TYPE
 156         };
 157         const char *name = "unknown sym type name";
 158         if (type < ARRAY_SIZE(type_name)) {
 159                 name = type_name[type];
 160         }
 161         return name;
 162 }
 163
 164 static const char *sym_bind(unsigned bind)
 165 {
 166         static const char *bind_name[] = {
 167 #define SYM_BIND(X) [X] = #X
 168                 SYM_BIND(STB_LOCAL),
 169                 SYM_BIND(STB_GLOBAL),
 170                 SYM_BIND(STB_WEAK),
 171 #undef SYM_BIND
 172         };
 173         const char *name = "unknown sym bind name";
 174         if (bind < ARRAY_SIZE(bind_name)) {
 175                 name = bind_name[bind];
 176         }
 177         return name;
 178 }
 179
 180 static const char *sym_visibility(unsigned visibility)
 181 {
 182         static const char *visibility_name[] = {
 183 #define SYM_VISIBILITY(X) [X] = #X
 184                 SYM_VISIBILITY(STV_DEFAULT),
 185                 SYM_VISIBILITY(STV_INTERNAL),
 186                 SYM_VISIBILITY(STV_HIDDEN),
 187                 SYM_VISIBILITY(STV_PROTECTED),
 188 #undef SYM_VISIBILITY
 189         };
 190         const char *name = "unknown sym visibility name";
 191         if (visibility < ARRAY_SIZE(visibility_name)) {
 192                 name = visibility_name[visibility];
 193         }
 194         return name;
 195 }
 196
 197 static const char *rel_type(unsigned type)
 198 {
 199         static const char *type_name[] = {
 200 #define REL_TYPE(X) [X] = #X
 201                 REL_TYPE(R_386_NONE),
 202                 REL_TYPE(R_386_32),
 203                 REL_TYPE(R_386_PC32),
 204                 REL_TYPE(R_386_GOT32),
 205                 REL_TYPE(R_386_PLT32),
 206                 REL_TYPE(R_386_COPY),
 207                 REL_TYPE(R_386_GLOB_DAT),
 208                 REL_TYPE(R_386_JMP_SLOT),
 209                 REL_TYPE(R_386_RELATIVE),
 210                 REL_TYPE(R_386_GOTOFF),
 211                 REL_TYPE(R_386_GOTPC),
 212                 REL_TYPE(R_386_8),
 213                 REL_TYPE(R_386_PC8),
 214                 REL_TYPE(R_386_16),
 215                 REL_TYPE(R_386_PC16),
 216 #undef REL_TYPE
 217         };
 218         const char *name = "unknown type rel type name";
 219         if (type < ARRAY_SIZE(type_name) && type_name[type]) {
 220                 name = type_name[type];
 221         }
 222         return name;
 223 }
 224
 225 static const char *sec_name(unsigned shndx)
 226 {
 227         const char *sec_strtab;
 228         const char *name;
 229         sec_strtab = secs[ehdr.e_shstrndx].strtab;
 230         name = "<noname>";
 231         if (shndx < ehdr.e_shnum) {
 232                 name = sec_strtab + secs[shndx].shdr.sh_name;
 233         }
 234         else if (shndx == SHN_ABS) {
 235                 name = "ABSOLUTE";
 236         }
 237         else if (shndx == SHN_COMMON) {
 238                 name = "COMMON";
 239         }
 240         return name;
 241 }
 242
 243 static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
 244 {
 245         const char *name;
 246         name = "<noname>";
 247         if (sym->st_name) {
 248                 name = sym_strtab + sym->st_name;
 249         }
 250         else {
 251                 name = sec_name(sym->st_shndx);
 252         }
 253         return name;
 254 }
 255
 256
 257
 258 #if BYTE_ORDER == LITTLE_ENDIAN
 259 #define le16_to_cpu(val) (val)
 260 #define le32_to_cpu(val) (val)
 261 #endif
 262 #if BYTE_ORDER == BIG_ENDIAN
 263 #define le16_to_cpu(val) bswap_16(val)
 264 #define le32_to_cpu(val) bswap_32(val)
 265 #endif
 266
 267 static uint16_t elf16_to_cpu(uint16_t val)
 268 {
 269         return le16_to_cpu(val);
 270 }
 271
 272 static uint32_t elf32_to_cpu(uint32_t val)
 273 {
 274         return le32_to_cpu(val);
 275 }
 276
 277 static void read_ehdr(FILE *fp)
 278 {
 279         if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
 280                 die("Cannot read ELF header: %s\n",
 281                         strerror(errno));
 282         }
 283         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
 284                 die("No ELF magic\n");
 285         }
 286         if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
 287                 die("Not a 32 bit executable\n");
 288         }
 289         if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
 290                 die("Not a LSB ELF executable\n");
 291         }
 292         if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
 293                 die("Unknown ELF version\n");
 294         }
 295         /* Convert the fields to native endian */
 296         ehdr.e_type      = elf16_to_cpu(ehdr.e_type);
 297         ehdr.e_machine   = elf16_to_cpu(ehdr.e_machine);
 298         ehdr.e_version   = elf32_to_cpu(ehdr.e_version);
 299         ehdr.e_entry     = elf32_to_cpu(ehdr.e_entry);
 300         ehdr.e_phoff     = elf32_to_cpu(ehdr.e_phoff);
 301         ehdr.e_shoff     = elf32_to_cpu(ehdr.e_shoff);
 302         ehdr.e_flags     = elf32_to_cpu(ehdr.e_flags);
 303         ehdr.e_ehsize    = elf16_to_cpu(ehdr.e_ehsize);
 304         ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
 305         ehdr.e_phnum     = elf16_to_cpu(ehdr.e_phnum);
 306         ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
 307         ehdr.e_shnum     = elf16_to_cpu(ehdr.e_shnum);
 308         ehdr.e_shstrndx  = elf16_to_cpu(ehdr.e_shstrndx);
 309
 310         if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
 311                 die("Unsupported ELF header type\n");
 312         }
 313         if (ehdr.e_machine != EM_386) {
 314                 die("Not for x86\n");
 315         }
 316         if (ehdr.e_version != EV_CURRENT) {
 317                 die("Unknown ELF version\n");
 318         }
 319         if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
 320                 die("Bad Elf header size\n");
 321         }
 322         if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
 323                 die("Bad program header entry\n");
 324         }
 325         if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
 326                 die("Bad section header entry\n");
 327         }
 328         if (ehdr.e_shstrndx >= ehdr.e_shnum) {
 329                 die("String table index out of bounds\n");
 330         }
 331 }
 332
 333 static void read_shdrs(FILE *fp)
 334 {
 335         int i;
 336         Elf32_Shdr shdr;
 337
 338         secs = calloc(ehdr.e_shnum, sizeof(struct section));
 339         if (!secs) {
 340                 die("Unable to allocate %d section headers\n",
 341                     ehdr.e_shnum);
 342         }
 343         if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
 344                 die("Seek to %d failed: %s\n",
 345                         ehdr.e_shoff, strerror(errno));
 346         }
 347         for (i = 0; i < ehdr.e_shnum; i++) {
 348                 struct section *sec = &secs[i];
 349                 if (fread(&shdr, sizeof shdr, 1, fp) != 1)
 350                         die("Cannot read ELF section headers %d/%d: %s\n",
 351                             i, ehdr.e_shnum, strerror(errno));
 352                 sec->shdr.sh_name      = elf32_to_cpu(shdr.sh_name);
 353                 sec->shdr.sh_type      = elf32_to_cpu(shdr.sh_type);
 354                 sec->shdr.sh_flags     = elf32_to_cpu(shdr.sh_flags);
 355                 sec->shdr.sh_addr      = elf32_to_cpu(shdr.sh_addr);
 356                 sec->shdr.sh_offset    = elf32_to_cpu(shdr.sh_offset);
 357                 sec->shdr.sh_size      = elf32_to_cpu(shdr.sh_size);
 358                 sec->shdr.sh_link      = elf32_to_cpu(shdr.sh_link);
 359                 sec->shdr.sh_info      = elf32_to_cpu(shdr.sh_info);
 360                 sec->shdr.sh_addralign = elf32_to_cpu(shdr.sh_addralign);
 361                 sec->shdr.sh_entsize   = elf32_to_cpu(shdr.sh_entsize);
 362                 if (sec->shdr.sh_link < ehdr.e_shnum)
 363                         sec->link = &secs[sec->shdr.sh_link];
 364         }
 365
 366 }
 367
 368 static void read_strtabs(FILE *fp)
 369 {
 370         int i;
 371         for (i = 0; i < ehdr.e_shnum; i++) {
 372                 struct section *sec = &secs[i];
 373                 if (sec->shdr.sh_type != SHT_STRTAB) {
 374                         continue;
 375                 }
 376                 sec->strtab = malloc(sec->shdr.sh_size);
 377                 if (!sec->strtab) {
 378                         die("malloc of %d bytes for strtab failed\n",
 379                                 sec->shdr.sh_size);
 380                 }
 381                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 382                         die("Seek to %d failed: %s\n",
 383                                 sec->shdr.sh_offset, strerror(errno));
 384                 }
 385                 if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
 386                     != sec->shdr.sh_size) {
 387                         die("Cannot read symbol table: %s\n",
 388                                 strerror(errno));
 389                 }
 390         }
 391 }
 392
 393 static void read_symtabs(FILE *fp)
 394 {
 395         int i,j;
 396         for (i = 0; i < ehdr.e_shnum; i++) {
 397                 struct section *sec = &secs[i];
 398                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 399                         continue;
 400                 }
 401                 sec->symtab = malloc(sec->shdr.sh_size);
 402                 if (!sec->symtab) {
 403                         die("malloc of %d bytes for symtab failed\n",
 404                                 sec->shdr.sh_size);
 405                 }
 406                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 407                         die("Seek to %d failed: %s\n",
 408                                 sec->shdr.sh_offset, strerror(errno));
 409                 }
 410                 if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
 411                     != sec->shdr.sh_size) {
 412                         die("Cannot read symbol table: %s\n",
 413                                 strerror(errno));
 414                 }
 415                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
 416                         Elf32_Sym *sym = &sec->symtab[j];
 417                         sym->st_name  = elf32_to_cpu(sym->st_name);
 418                         sym->st_value = elf32_to_cpu(sym->st_value);
 419                         sym->st_size  = elf32_to_cpu(sym->st_size);
 420                         sym->st_shndx = elf16_to_cpu(sym->st_shndx);
 421                 }
 422         }
 423 }
 424
 425
 426 static void read_relocs(FILE *fp)
 427 {
 428         int i,j;
 429         for (i = 0; i < ehdr.e_shnum; i++) {
 430                 struct section *sec = &secs[i];
 431                 if (sec->shdr.sh_type != SHT_REL) {
 432                         continue;
 433                 }
 434                 sec->reltab = malloc(sec->shdr.sh_size);
 435                 if (!sec->reltab) {
 436                         die("malloc of %d bytes for relocs failed\n",
 437                                 sec->shdr.sh_size);
 438                 }
 439                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 440                         die("Seek to %d failed: %s\n",
 441                                 sec->shdr.sh_offset, strerror(errno));
 442                 }
 443                 if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
 444                     != sec->shdr.sh_size) {
 445                         die("Cannot read symbol table: %s\n",
 446                                 strerror(errno));
 447                 }
 448                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
 449                         Elf32_Rel *rel = &sec->reltab[j];
 450                         rel->r_offset = elf32_to_cpu(rel->r_offset);
 451                         rel->r_info   = elf32_to_cpu(rel->r_info);
 452                 }
 453         }
 454 }
 455
 456
 457 static void print_absolute_symbols(void)
 458 {
 459         int i;
 460         printf("Absolute symbols\n");
 461         printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
 462         for (i = 0; i < ehdr.e_shnum; i++) {
 463                 struct section *sec = &secs[i];
 464                 char *sym_strtab;
 465                 int j;
 466
 467                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 468                         continue;
 469                 }
 470                 sym_strtab = sec->link->strtab;
 471                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) {
 472                         Elf32_Sym *sym;
 473                         const char *name;
 474                         sym = &sec->symtab[j];
 475                         name = sym_name(sym_strtab, sym);
 476                         if (sym->st_shndx != SHN_ABS) {
 477                                 continue;
 478                         }
 479                         printf("%5d %08x %5d %10s %10s %12s %s\n",
 480                                 j, sym->st_value, sym->st_size,
 481                                 sym_type(ELF32_ST_TYPE(sym->st_info)),
 482                                 sym_bind(ELF32_ST_BIND(sym->st_info)),
 483                                 sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
 484                                 name);
 485                 }
 486         }
 487         printf("\n");
 488 }
 489
 490 static void print_absolute_relocs(void)
 491 {
 492         int i, printed = 0;
 493
 494         for (i = 0; i < ehdr.e_shnum; i++) {
 495                 struct section *sec = &secs[i];
 496                 struct section *sec_applies, *sec_symtab;
 497                 char *sym_strtab;
 498                 Elf32_Sym *sh_symtab;
 499                 int j;
 500                 if (sec->shdr.sh_type != SHT_REL) {
 501                         continue;
 502                 }
 503                 sec_symtab  = sec->link;
 504                 sec_applies = &secs[sec->shdr.sh_info];
 505                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 506                         continue;
 507                 }
 508                 sh_symtab  = sec_symtab->symtab;
 509                 sym_strtab = sec_symtab->link->strtab;
 510                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
 511                         Elf32_Rel *rel;
 512                         Elf32_Sym *sym;
 513                         const char *name;
 514                         rel = &sec->reltab[j];
 515                         sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
 516                         name = sym_name(sym_strtab, sym);
 517                         if (sym->st_shndx != SHN_ABS) {
 518                                 continue;
 519                         }
 520
 521                         /* Absolute symbols are not relocated if bzImage is
 522                          * loaded at a non-compiled address. Display a warning
 523                          * to user at compile time about the absolute
 524                          * relocations present.
 525                          *
 526                          * User need to audit the code to make sure
 527                          * some symbols which should have been section
 528                          * relative have not become absolute because of some
 529                          * linker optimization or wrong programming usage.
 530                          *
 531                          * Before warning check if this absolute symbol
 532                          * relocation is harmless.
 533                          */
 534                         if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
 535                                 continue;
 536
 537                         if (!printed) {
 538                                 printf("WARNING: Absolute relocations"
 539                                         " present\n");
 540                                 printf("Offset     Info     Type     Sym.Value "
 541                                         "Sym.Name\n");
 542                                 printed = 1;
 543                         }
 544
 545                         printf("%08x %08x %10s %08x  %s\n",
 546                                 rel->r_offset,
 547                                 rel->r_info,
 548                                 rel_type(ELF32_R_TYPE(rel->r_info)),
 549                                 sym->st_value,
 550                                 name);
 551                 }
 552         }
 553
 554         if (printed)
 555                 printf("\n");
 556 }
 557
 558 static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym),
 559                         int use_real_mode)
 560 {
 561         int i;
 562         /* Walk through the relocations */
 563         for (i = 0; i < ehdr.e_shnum; i++) {
 564                 char *sym_strtab;
 565                 Elf32_Sym *sh_symtab;
 566                 struct section *sec_applies, *sec_symtab;
 567                 int j;
 568                 struct section *sec = &secs[i];
 569
 570                 if (sec->shdr.sh_type != SHT_REL) {
 571                         continue;
 572                 }
 573                 sec_symtab  = sec->link;
 574                 sec_applies = &secs[sec->shdr.sh_info];
 575                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 576                         continue;
 577                 }
 578                 sh_symtab = sec_symtab->symtab;
 579                 sym_strtab = sec_symtab->link->strtab;
 580                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) {
 581                         Elf32_Rel *rel;
 582                         Elf32_Sym *sym;
 583                         unsigned r_type;
 584                         const char *symname;
 585                         int shn_abs;
 586
 587                         rel = &sec->reltab[j];
 588                         sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
 589                         r_type = ELF32_R_TYPE(rel->r_info);
 590
 591                         shn_abs = sym->st_shndx == SHN_ABS;
 592
 593                         switch (r_type) {
 594                         case R_386_NONE:
 595                         case R_386_PC32:
 596                         case R_386_PC16:
 597                         case R_386_PC8:
 598                                 /*
 599                                  * NONE can be ignored and and PC relative
 600                                  * relocations don't need to be adjusted.
 601                                  */
 602                                 break;
 603
 604                         case R_386_16:
 605                                 symname = sym_name(sym_strtab, sym);
 606                                 if (!use_real_mode)
 607                                         goto bad;
 608                                 if (shn_abs) {
 609                                         if (is_reloc(S_ABS, symname))
 610                                                 break;
 611                                         else if (!is_reloc(S_SEG, symname))
 612                                                 goto bad;
 613                                 } else {
 614                                         if (is_reloc(S_LIN, symname))
 615                                                 goto bad;
 616                                         else
 617                                                 break;
 618                                 }
 619                                 visit(rel, sym);
 620                                 break;
 621
 622                         case R_386_32:
 623                                 symname = sym_name(sym_strtab, sym);
 624                                 if (shn_abs) {
 625                                         if (is_reloc(S_ABS, symname))
 626                                                 break;
 627                                         else if (!is_reloc(S_REL, symname))
 628                                                 goto bad;
 629                                 } else {
 630                                         if (use_real_mode &&
 631                                             !is_reloc(S_LIN, symname))
 632                                                 break;
 633                                 }
 634                                 visit(rel, sym);
 635                                 break;
 636                         default:
 637                                 die("Unsupported relocation type: %s (%d)\n",
 638                                     rel_type(r_type), r_type);
 639                                 break;
 640                         bad:
 641                                 symname = sym_name(sym_strtab, sym);
 642                                 die("Invalid %s %s relocation: %s\n",
 643                                     shn_abs ? "absolute" : "relative",
 644                                     rel_type(r_type), symname);
 645                         }
 646                 }
 647         }
 648 }
 649
 650 static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
 651 {
 652         if (ELF32_R_TYPE(rel->r_info) == R_386_16)
 653                 reloc16_count++;
 654         else
 655                 reloc_count++;
 656 }
 657
 658 static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
 659 {
 660         /* Remember the address that needs to be adjusted. */
 661         if (ELF32_R_TYPE(rel->r_info) == R_386_16)
 662                 relocs16[reloc16_idx++] = rel->r_offset;
 663         else
 664                 relocs[reloc_idx++] = rel->r_offset;
 665 }
 666
 667 static int cmp_relocs(const void *va, const void *vb)
 668 {
 669         const unsigned long *a, *b;
 670         a = va; b = vb;
 671         return (*a == *b)? 0 : (*a > *b)? 1 : -1;
 672 }
 673
 674 static int write32(unsigned int v, FILE *f)
 675 {
 676         unsigned char buf[4];
 677
 678         put_unaligned_le32(v, buf);
 679         return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
 680 }
 681
 682 static void emit_relocs(int as_text, int use_real_mode)
 683 {
 684         int i;
 685         /* Count how many relocations I have and allocate space for them. */
 686         reloc_count = 0;
 687         walk_relocs(count_reloc, use_real_mode);
 688         relocs = malloc(reloc_count * sizeof(relocs[0]));
 689         if (!relocs) {
 690                 die("malloc of %d entries for relocs failed\n",
 691                         reloc_count);
 692         }
 693
 694         relocs16 = malloc(reloc16_count * sizeof(relocs[0]));
 695         if (!relocs16) {
 696                 die("malloc of %d entries for relocs16 failed\n",
 697                         reloc16_count);
 698         }
 699         /* Collect up the relocations */
 700         reloc_idx = 0;
 701         walk_relocs(collect_reloc, use_real_mode);
 702
 703         if (reloc16_count && !use_real_mode)
 704                 die("Segment relocations found but --realmode not specified\n");
 705
 706         /* Order the relocations for more efficient processing */
 707         qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
 708         qsort(relocs16, reloc16_count, sizeof(relocs16[0]), cmp_relocs);
 709
 710         /* Print the relocations */
 711         if (as_text) {
 712                 /* Print the relocations in a form suitable that
 713                  * gas will like.
 714                  */
 715                 printf(".section \".data.reloc\",\"a\"\n");
 716                 printf(".balign 4\n");
 717                 if (use_real_mode) {
 718                         printf("\t.long %lu\n", reloc16_count);
 719                         for (i = 0; i < reloc16_count; i++)
 720                                 printf("\t.long 0x%08lx\n", relocs16[i]);
 721                         printf("\t.long %lu\n", reloc_count);
 722                         for (i = 0; i < reloc_count; i++) {
 723                                 printf("\t.long 0x%08lx\n", relocs[i]);
 724                         }
 725                 } else {
 726                         /* Print a stop */
 727                         printf("\t.long 0x%08lx\n", (unsigned long)0);
 728                         for (i = 0; i < reloc_count; i++) {
 729                                 printf("\t.long 0x%08lx\n", relocs[i]);
 730                         }
 731                 }
 732
 733                 printf("\n");
 734         }
 735         else {
 736                 if (use_real_mode) {
 737                         write32(reloc16_count, stdout);
 738                         for (i = 0; i < reloc16_count; i++)
 739                                 write32(relocs16[i], stdout);
 740                         write32(reloc_count, stdout);
 741
 742                         /* Now print each relocation */
 743                         for (i = 0; i < reloc_count; i++)
 744                                 write32(relocs[i], stdout);
 745                 } else {
 746                         /* Print a stop */
 747                         write32(0, stdout);
 748
 749                         /* Now print each relocation */
 750                         for (i = 0; i < reloc_count; i++) {
 751                                 write32(relocs[i], stdout);
 752                         }
 753                 }
 754         }
 755 }
 756
 757 static void usage(void)
 758 {
 759         die("relocs [--abs-syms|--abs-relocs|--text|--realmode] vmlinux\n");
 760 }
 761
 762 int main(int argc, char **argv)
 763 {
 764         int show_absolute_syms, show_absolute_relocs;
 765         int as_text, use_real_mode;
 766         const char *fname;
 767         FILE *fp;
 768         int i;
 769
 770         show_absolute_syms = 0;
 771         show_absolute_relocs = 0;
 772         as_text = 0;
 773         use_real_mode = 0;
 774         fname = NULL;
 775         for (i = 1; i < argc; i++) {
 776                 char *arg = argv[i];
 777                 if (*arg == '-') {
 778                         if (strcmp(arg, "--abs-syms") == 0) {
 779                                 show_absolute_syms = 1;
 780                                 continue;
 781                         }
 782                         if (strcmp(arg, "--abs-relocs") == 0) {
 783                                 show_absolute_relocs = 1;
 784                                 continue;
 785                         }
 786                         if (strcmp(arg, "--text") == 0) {
 787                                 as_text = 1;
 788                                 continue;
 789                         }
 790                         if (strcmp(arg, "--realmode") == 0) {
 791                                 use_real_mode = 1;
 792                                 continue;
 793                         }
 794                 }
 795                 else if (!fname) {
 796                         fname = arg;
 797                         continue;
 798                 }
 799                 usage();
 800         }
 801         if (!fname) {
 802                 usage();
 803         }
 804         regex_init(use_real_mode);
 805         fp = fopen(fname, "r");
 806         if (!fp) {
 807                 die("Cannot open %s: %s\n",
 808                         fname, strerror(errno));
 809         }
 810         read_ehdr(fp);
 811         read_shdrs(fp);
 812         read_strtabs(fp);
 813         read_symtabs(fp);
 814         read_relocs(fp);
 815         if (show_absolute_syms) {
 816                 print_absolute_symbols();
 817                 return 0;
 818         }
 819         if (show_absolute_relocs) {
 820                 print_absolute_relocs();
 821                 return 0;
 822         }
 823         emit_relocs(as_text, use_real_mode);
 824         return 0;
 825 }