arch/x86/tools/relocs.c

   1 /* This is included from relocs_32/64.c */
   2
   3 #define ElfW(type)              _ElfW(ELF_BITS, type)
   4 #define _ElfW(bits, type)       __ElfW(bits, type)
   5 #define __ElfW(bits, type)      Elf##bits##_##type
   6
   7 #define Elf_Addr                ElfW(Addr)
   8 #define Elf_Ehdr                ElfW(Ehdr)
   9 #define Elf_Phdr                ElfW(Phdr)
  10 #define Elf_Shdr                ElfW(Shdr)
  11 #define Elf_Sym                 ElfW(Sym)
  12
  13 static Elf_Ehdr ehdr;
  14
  15 struct relocs {
  16         uint32_t        *offset;
  17         unsigned long   count;
  18         unsigned long   size;
  19 };
  20
  21 static struct relocs relocs16;
  22 static struct relocs relocs32;
  23 static struct relocs relocs64;
  24
  25 struct section {
  26         Elf_Shdr       shdr;
  27         struct section *link;
  28         Elf_Sym        *symtab;
  29         Elf_Rel        *reltab;
  30         char           *strtab;
  31 };
  32 static struct section *secs;
  33
  34 static const char * const sym_regex_kernel[S_NSYMTYPES] = {
  35 /*
  36  * Following symbols have been audited. There values are constant and do
  37  * not change if bzImage is loaded at a different physical address than
  38  * the address for which it has been compiled. Don't warn user about
  39  * absolute relocations present w.r.t these symbols.
  40  */
  41         [S_ABS] =
  42         "^(xen_irq_disable_direct_reloc$|"
  43         "xen_save_fl_direct_reloc$|"
  44         "VDSO|"
  45         "__crc_)",
  46
  47 /*
  48  * These symbols are known to be relative, even if the linker marks them
  49  * as absolute (typically defined outside any section in the linker script.)
  50  */
  51         [S_REL] =
  52         "^(__init_(begin|end)|"
  53         "__x86_cpu_dev_(start|end)|"
  54         "(__parainstructions|__alt_instructions)(|_end)|"
  55         "(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
  56         "__(start|end)_pci_.*|"
  57         "__(start|end)_builtin_fw|"
  58         "__(start|stop)___ksymtab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
  59         "__(start|stop)___kcrctab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
  60         "__(start|stop)___param|"
  61         "__(start|stop)___modver|"
  62         "__(start|stop)___bug_table|"
  63         "__tracedata_(start|end)|"
  64         "__(start|stop)_notes|"
  65         "__end_rodata|"
  66         "__initramfs_start|"
  67         "(jiffies|jiffies_64)|"
  68 #if ELF_BITS == 64
  69         "__per_cpu_load|"
  70         "init_per_cpu__.*|"
  71         "__end_rodata_hpage_align|"
  72         "__vvar_page|"
  73 #endif
  74         "_end)$"
  75 };
  76
  77
  78 static const char * const sym_regex_realmode[S_NSYMTYPES] = {
  79 /*
  80  * These symbols are known to be relative, even if the linker marks them
  81  * as absolute (typically defined outside any section in the linker script.)
  82  */
  83         [S_REL] =
  84         "^pa_",
  85
  86 /*
  87  * These are 16-bit segment symbols when compiling 16-bit code.
  88  */
  89         [S_SEG] =
  90         "^real_mode_seg$",
  91
  92 /*
  93  * These are offsets belonging to segments, as opposed to linear addresses,
  94  * when compiling 16-bit code.
  95  */
  96         [S_LIN] =
  97         "^pa_",
  98 };
  99
 100 static const char * const *sym_regex;
 101
 102 static regex_t sym_regex_c[S_NSYMTYPES];
 103 static int is_reloc(enum symtype type, const char *sym_name)
 104 {
 105         return sym_regex[type] &&
 106                 !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
 107 }
 108
 109 static void regex_init(int use_real_mode)
 110 {
 111         char errbuf[128];
 112         int err;
 113         int i;
 114
 115         if (use_real_mode)
 116                 sym_regex = sym_regex_realmode;
 117         else
 118                 sym_regex = sym_regex_kernel;
 119
 120         for (i = 0; i < S_NSYMTYPES; i++) {
 121                 if (!sym_regex[i])
 122                         continue;
 123
 124                 err = regcomp(&sym_regex_c[i], sym_regex[i],
 125                               REG_EXTENDED|REG_NOSUB);
 126
 127                 if (err) {
 128                         regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
 129                         die("%s", errbuf);
 130                 }
 131         }
 132 }
 133
 134 static const char *sym_type(unsigned type)
 135 {
 136         static const char *type_name[] = {
 137 #define SYM_TYPE(X) [X] = #X
 138                 SYM_TYPE(STT_NOTYPE),
 139                 SYM_TYPE(STT_OBJECT),
 140                 SYM_TYPE(STT_FUNC),
 141                 SYM_TYPE(STT_SECTION),
 142                 SYM_TYPE(STT_FILE),
 143                 SYM_TYPE(STT_COMMON),
 144                 SYM_TYPE(STT_TLS),
 145 #undef SYM_TYPE
 146         };
 147         const char *name = "unknown sym type name";
 148         if (type < ARRAY_SIZE(type_name)) {
 149                 name = type_name[type];
 150         }
 151         return name;
 152 }
 153
 154 static const char *sym_bind(unsigned bind)
 155 {
 156         static const char *bind_name[] = {
 157 #define SYM_BIND(X) [X] = #X
 158                 SYM_BIND(STB_LOCAL),
 159                 SYM_BIND(STB_GLOBAL),
 160                 SYM_BIND(STB_WEAK),
 161 #undef SYM_BIND
 162         };
 163         const char *name = "unknown sym bind name";
 164         if (bind < ARRAY_SIZE(bind_name)) {
 165                 name = bind_name[bind];
 166         }
 167         return name;
 168 }
 169
 170 static const char *sym_visibility(unsigned visibility)
 171 {
 172         static const char *visibility_name[] = {
 173 #define SYM_VISIBILITY(X) [X] = #X
 174                 SYM_VISIBILITY(STV_DEFAULT),
 175                 SYM_VISIBILITY(STV_INTERNAL),
 176                 SYM_VISIBILITY(STV_HIDDEN),
 177                 SYM_VISIBILITY(STV_PROTECTED),
 178 #undef SYM_VISIBILITY
 179         };
 180         const char *name = "unknown sym visibility name";
 181         if (visibility < ARRAY_SIZE(visibility_name)) {
 182                 name = visibility_name[visibility];
 183         }
 184         return name;
 185 }
 186
 187 static const char *rel_type(unsigned type)
 188 {
 189         static const char *type_name[] = {
 190 #define REL_TYPE(X) [X] = #X
 191 #if ELF_BITS == 64
 192                 REL_TYPE(R_X86_64_NONE),
 193                 REL_TYPE(R_X86_64_64),
 194                 REL_TYPE(R_X86_64_PC32),
 195                 REL_TYPE(R_X86_64_GOT32),
 196                 REL_TYPE(R_X86_64_PLT32),
 197                 REL_TYPE(R_X86_64_COPY),
 198                 REL_TYPE(R_X86_64_GLOB_DAT),
 199                 REL_TYPE(R_X86_64_JUMP_SLOT),
 200                 REL_TYPE(R_X86_64_RELATIVE),
 201                 REL_TYPE(R_X86_64_GOTPCREL),
 202                 REL_TYPE(R_X86_64_32),
 203                 REL_TYPE(R_X86_64_32S),
 204                 REL_TYPE(R_X86_64_16),
 205                 REL_TYPE(R_X86_64_PC16),
 206                 REL_TYPE(R_X86_64_8),
 207                 REL_TYPE(R_X86_64_PC8),
 208 #else
 209                 REL_TYPE(R_386_NONE),
 210                 REL_TYPE(R_386_32),
 211                 REL_TYPE(R_386_PC32),
 212                 REL_TYPE(R_386_GOT32),
 213                 REL_TYPE(R_386_PLT32),
 214                 REL_TYPE(R_386_COPY),
 215                 REL_TYPE(R_386_GLOB_DAT),
 216                 REL_TYPE(R_386_JMP_SLOT),
 217                 REL_TYPE(R_386_RELATIVE),
 218                 REL_TYPE(R_386_GOTOFF),
 219                 REL_TYPE(R_386_GOTPC),
 220                 REL_TYPE(R_386_8),
 221                 REL_TYPE(R_386_PC8),
 222                 REL_TYPE(R_386_16),
 223                 REL_TYPE(R_386_PC16),
 224 #endif
 225 #undef REL_TYPE
 226         };
 227         const char *name = "unknown type rel type name";
 228         if (type < ARRAY_SIZE(type_name) && type_name[type]) {
 229                 name = type_name[type];
 230         }
 231         return name;
 232 }
 233
 234 static const char *sec_name(unsigned shndx)
 235 {
 236         const char *sec_strtab;
 237         const char *name;
 238         sec_strtab = secs[ehdr.e_shstrndx].strtab;
 239         name = "<noname>";
 240         if (shndx < ehdr.e_shnum) {
 241                 name = sec_strtab + secs[shndx].shdr.sh_name;
 242         }
 243         else if (shndx == SHN_ABS) {
 244                 name = "ABSOLUTE";
 245         }
 246         else if (shndx == SHN_COMMON) {
 247                 name = "COMMON";
 248         }
 249         return name;
 250 }
 251
 252 static const char *sym_name(const char *sym_strtab, Elf_Sym *sym)
 253 {
 254         const char *name;
 255         name = "<noname>";
 256         if (sym->st_name) {
 257                 name = sym_strtab + sym->st_name;
 258         }
 259         else {
 260                 name = sec_name(sym->st_shndx);
 261         }
 262         return name;
 263 }
 264
 265 static Elf_Sym *sym_lookup(const char *symname)
 266 {
 267         int i;
 268         for (i = 0; i < ehdr.e_shnum; i++) {
 269                 struct section *sec = &secs[i];
 270                 long nsyms;
 271                 char *strtab;
 272                 Elf_Sym *symtab;
 273                 Elf_Sym *sym;
 274
 275                 if (sec->shdr.sh_type != SHT_SYMTAB)
 276                         continue;
 277
 278                 nsyms = sec->shdr.sh_size/sizeof(Elf_Sym);
 279                 symtab = sec->symtab;
 280                 strtab = sec->link->strtab;
 281
 282                 for (sym = symtab; --nsyms >= 0; sym++) {
 283                         if (!sym->st_name)
 284                                 continue;
 285                         if (strcmp(symname, strtab + sym->st_name) == 0)
 286                                 return sym;
 287                 }
 288         }
 289         return 0;
 290 }
 291
 292 #if BYTE_ORDER == LITTLE_ENDIAN
 293 #define le16_to_cpu(val) (val)
 294 #define le32_to_cpu(val) (val)
 295 #define le64_to_cpu(val) (val)
 296 #endif
 297 #if BYTE_ORDER == BIG_ENDIAN
 298 #define le16_to_cpu(val) bswap_16(val)
 299 #define le32_to_cpu(val) bswap_32(val)
 300 #define le64_to_cpu(val) bswap_64(val)
 301 #endif
 302
 303 static uint16_t elf16_to_cpu(uint16_t val)
 304 {
 305         return le16_to_cpu(val);
 306 }
 307
 308 static uint32_t elf32_to_cpu(uint32_t val)
 309 {
 310         return le32_to_cpu(val);
 311 }
 312
 313 #define elf_half_to_cpu(x)      elf16_to_cpu(x)
 314 #define elf_word_to_cpu(x)      elf32_to_cpu(x)
 315
 316 #if ELF_BITS == 64
 317 static uint64_t elf64_to_cpu(uint64_t val)
 318 {
 319         return le64_to_cpu(val);
 320 }
 321 #define elf_addr_to_cpu(x)      elf64_to_cpu(x)
 322 #define elf_off_to_cpu(x)       elf64_to_cpu(x)
 323 #define elf_xword_to_cpu(x)     elf64_to_cpu(x)
 324 #else
 325 #define elf_addr_to_cpu(x)      elf32_to_cpu(x)
 326 #define elf_off_to_cpu(x)       elf32_to_cpu(x)
 327 #define elf_xword_to_cpu(x)     elf32_to_cpu(x)
 328 #endif
 329
 330 static void read_ehdr(FILE *fp)
 331 {
 332         if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
 333                 die("Cannot read ELF header: %s\n",
 334                         strerror(errno));
 335         }
 336         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
 337                 die("No ELF magic\n");
 338         }
 339         if (ehdr.e_ident[EI_CLASS] != ELF_CLASS) {
 340                 die("Not a %d bit executable\n", ELF_BITS);
 341         }
 342         if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
 343                 die("Not a LSB ELF executable\n");
 344         }
 345         if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
 346                 die("Unknown ELF version\n");
 347         }
 348         /* Convert the fields to native endian */
 349         ehdr.e_type      = elf_half_to_cpu(ehdr.e_type);
 350         ehdr.e_machine   = elf_half_to_cpu(ehdr.e_machine);
 351         ehdr.e_version   = elf_word_to_cpu(ehdr.e_version);
 352         ehdr.e_entry     = elf_addr_to_cpu(ehdr.e_entry);
 353         ehdr.e_phoff     = elf_off_to_cpu(ehdr.e_phoff);
 354         ehdr.e_shoff     = elf_off_to_cpu(ehdr.e_shoff);
 355         ehdr.e_flags     = elf_word_to_cpu(ehdr.e_flags);
 356         ehdr.e_ehsize    = elf_half_to_cpu(ehdr.e_ehsize);
 357         ehdr.e_phentsize = elf_half_to_cpu(ehdr.e_phentsize);
 358         ehdr.e_phnum     = elf_half_to_cpu(ehdr.e_phnum);
 359         ehdr.e_shentsize = elf_half_to_cpu(ehdr.e_shentsize);
 360         ehdr.e_shnum     = elf_half_to_cpu(ehdr.e_shnum);
 361         ehdr.e_shstrndx  = elf_half_to_cpu(ehdr.e_shstrndx);
 362
 363         if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
 364                 die("Unsupported ELF header type\n");
 365         }
 366         if (ehdr.e_machine != ELF_MACHINE) {
 367                 die("Not for %s\n", ELF_MACHINE_NAME);
 368         }
 369         if (ehdr.e_version != EV_CURRENT) {
 370                 die("Unknown ELF version\n");
 371         }
 372         if (ehdr.e_ehsize != sizeof(Elf_Ehdr)) {
 373                 die("Bad Elf header size\n");
 374         }
 375         if (ehdr.e_phentsize != sizeof(Elf_Phdr)) {
 376                 die("Bad program header entry\n");
 377         }
 378         if (ehdr.e_shentsize != sizeof(Elf_Shdr)) {
 379                 die("Bad section header entry\n");
 380         }
 381         if (ehdr.e_shstrndx >= ehdr.e_shnum) {
 382                 die("String table index out of bounds\n");
 383         }
 384 }
 385
 386 static void read_shdrs(FILE *fp)
 387 {
 388         int i;
 389         Elf_Shdr shdr;
 390
 391         secs = calloc(ehdr.e_shnum, sizeof(struct section));
 392         if (!secs) {
 393                 die("Unable to allocate %d section headers\n",
 394                     ehdr.e_shnum);
 395         }
 396         if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
 397                 die("Seek to %d failed: %s\n",
 398                         ehdr.e_shoff, strerror(errno));
 399         }
 400         for (i = 0; i < ehdr.e_shnum; i++) {
 401                 struct section *sec = &secs[i];
 402                 if (fread(&shdr, sizeof shdr, 1, fp) != 1)
 403                         die("Cannot read ELF section headers %d/%d: %s\n",
 404                             i, ehdr.e_shnum, strerror(errno));
 405                 sec->shdr.sh_name      = elf_word_to_cpu(shdr.sh_name);
 406                 sec->shdr.sh_type      = elf_word_to_cpu(shdr.sh_type);
 407                 sec->shdr.sh_flags     = elf_xword_to_cpu(shdr.sh_flags);
 408                 sec->shdr.sh_addr      = elf_addr_to_cpu(shdr.sh_addr);
 409                 sec->shdr.sh_offset    = elf_off_to_cpu(shdr.sh_offset);
 410                 sec->shdr.sh_size      = elf_xword_to_cpu(shdr.sh_size);
 411                 sec->shdr.sh_link      = elf_word_to_cpu(shdr.sh_link);
 412                 sec->shdr.sh_info      = elf_word_to_cpu(shdr.sh_info);
 413                 sec->shdr.sh_addralign = elf_xword_to_cpu(shdr.sh_addralign);
 414                 sec->shdr.sh_entsize   = elf_xword_to_cpu(shdr.sh_entsize);
 415                 if (sec->shdr.sh_link < ehdr.e_shnum)
 416                         sec->link = &secs[sec->shdr.sh_link];
 417         }
 418
 419 }
 420
 421 static void read_strtabs(FILE *fp)
 422 {
 423         int i;
 424         for (i = 0; i < ehdr.e_shnum; i++) {
 425                 struct section *sec = &secs[i];
 426                 if (sec->shdr.sh_type != SHT_STRTAB) {
 427                         continue;
 428                 }
 429                 sec->strtab = malloc(sec->shdr.sh_size);
 430                 if (!sec->strtab) {
 431                         die("malloc of %d bytes for strtab failed\n",
 432                                 sec->shdr.sh_size);
 433                 }
 434                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 435                         die("Seek to %d failed: %s\n",
 436                                 sec->shdr.sh_offset, strerror(errno));
 437                 }
 438                 if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
 439                     != sec->shdr.sh_size) {
 440                         die("Cannot read symbol table: %s\n",
 441                                 strerror(errno));
 442                 }
 443         }
 444 }
 445
 446 static void read_symtabs(FILE *fp)
 447 {
 448         int i,j;
 449         for (i = 0; i < ehdr.e_shnum; i++) {
 450                 struct section *sec = &secs[i];
 451                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 452                         continue;
 453                 }
 454                 sec->symtab = malloc(sec->shdr.sh_size);
 455                 if (!sec->symtab) {
 456                         die("malloc of %d bytes for symtab failed\n",
 457                                 sec->shdr.sh_size);
 458                 }
 459                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 460                         die("Seek to %d failed: %s\n",
 461                                 sec->shdr.sh_offset, strerror(errno));
 462                 }
 463                 if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
 464                     != sec->shdr.sh_size) {
 465                         die("Cannot read symbol table: %s\n",
 466                                 strerror(errno));
 467                 }
 468                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
 469                         Elf_Sym *sym = &sec->symtab[j];
 470                         sym->st_name  = elf_word_to_cpu(sym->st_name);
 471                         sym->st_value = elf_addr_to_cpu(sym->st_value);
 472                         sym->st_size  = elf_xword_to_cpu(sym->st_size);
 473                         sym->st_shndx = elf_half_to_cpu(sym->st_shndx);
 474                 }
 475         }
 476 }
 477
 478
 479 static void read_relocs(FILE *fp)
 480 {
 481         int i,j;
 482         for (i = 0; i < ehdr.e_shnum; i++) {
 483                 struct section *sec = &secs[i];
 484                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 485                         continue;
 486                 }
 487                 sec->reltab = malloc(sec->shdr.sh_size);
 488                 if (!sec->reltab) {
 489                         die("malloc of %d bytes for relocs failed\n",
 490                                 sec->shdr.sh_size);
 491                 }
 492                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 493                         die("Seek to %d failed: %s\n",
 494                                 sec->shdr.sh_offset, strerror(errno));
 495                 }
 496                 if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
 497                     != sec->shdr.sh_size) {
 498                         die("Cannot read symbol table: %s\n",
 499                                 strerror(errno));
 500                 }
 501                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 502                         Elf_Rel *rel = &sec->reltab[j];
 503                         rel->r_offset = elf_addr_to_cpu(rel->r_offset);
 504                         rel->r_info   = elf_xword_to_cpu(rel->r_info);
 505 #if (SHT_REL_TYPE == SHT_RELA)
 506                         rel->r_addend = elf_xword_to_cpu(rel->r_addend);
 507 #endif
 508                 }
 509         }
 510 }
 511
 512
 513 static void print_absolute_symbols(void)
 514 {
 515         int i;
 516         const char *format;
 517
 518         if (ELF_BITS == 64)
 519                 format = "%5d %016"PRIx64" %5"PRId64" %10s %10s %12s %s\n";
 520         else
 521                 format = "%5d %08"PRIx32"  %5"PRId32" %10s %10s %12s %s\n";
 522
 523         printf("Absolute symbols\n");
 524         printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
 525         for (i = 0; i < ehdr.e_shnum; i++) {
 526                 struct section *sec = &secs[i];
 527                 char *sym_strtab;
 528                 int j;
 529
 530                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 531                         continue;
 532                 }
 533                 sym_strtab = sec->link->strtab;
 534                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
 535                         Elf_Sym *sym;
 536                         const char *name;
 537                         sym = &sec->symtab[j];
 538                         name = sym_name(sym_strtab, sym);
 539                         if (sym->st_shndx != SHN_ABS) {
 540                                 continue;
 541                         }
 542                         printf(format,
 543                                 j, sym->st_value, sym->st_size,
 544                                 sym_type(ELF_ST_TYPE(sym->st_info)),
 545                                 sym_bind(ELF_ST_BIND(sym->st_info)),
 546                                 sym_visibility(ELF_ST_VISIBILITY(sym->st_other)),
 547                                 name);
 548                 }
 549         }
 550         printf("\n");
 551 }
 552
 553 static void print_absolute_relocs(void)
 554 {
 555         int i, printed = 0;
 556         const char *format;
 557
 558         if (ELF_BITS == 64)
 559                 format = "%016"PRIx64" %016"PRIx64" %10s %016"PRIx64"  %s\n";
 560         else
 561                 format = "%08"PRIx32" %08"PRIx32" %10s %08"PRIx32"  %s\n";
 562
 563         for (i = 0; i < ehdr.e_shnum; i++) {
 564                 struct section *sec = &secs[i];
 565                 struct section *sec_applies, *sec_symtab;
 566                 char *sym_strtab;
 567                 Elf_Sym *sh_symtab;
 568                 int j;
 569                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 570                         continue;
 571                 }
 572                 sec_symtab  = sec->link;
 573                 sec_applies = &secs[sec->shdr.sh_info];
 574                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 575                         continue;
 576                 }
 577                 sh_symtab  = sec_symtab->symtab;
 578                 sym_strtab = sec_symtab->link->strtab;
 579                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 580                         Elf_Rel *rel;
 581                         Elf_Sym *sym;
 582                         const char *name;
 583                         rel = &sec->reltab[j];
 584                         sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
 585                         name = sym_name(sym_strtab, sym);
 586                         if (sym->st_shndx != SHN_ABS) {
 587                                 continue;
 588                         }
 589
 590                         /* Absolute symbols are not relocated if bzImage is
 591                          * loaded at a non-compiled address. Display a warning
 592                          * to user at compile time about the absolute
 593                          * relocations present.
 594                          *
 595                          * User need to audit the code to make sure
 596                          * some symbols which should have been section
 597                          * relative have not become absolute because of some
 598                          * linker optimization or wrong programming usage.
 599                          *
 600                          * Before warning check if this absolute symbol
 601                          * relocation is harmless.
 602                          */
 603                         if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
 604                                 continue;
 605
 606                         if (!printed) {
 607                                 printf("WARNING: Absolute relocations"
 608                                         " present\n");
 609                                 printf("Offset     Info     Type     Sym.Value "
 610                                         "Sym.Name\n");
 611                                 printed = 1;
 612                         }
 613
 614                         printf(format,
 615                                 rel->r_offset,
 616                                 rel->r_info,
 617                                 rel_type(ELF_R_TYPE(rel->r_info)),
 618                                 sym->st_value,
 619                                 name);
 620                 }
 621         }
 622
 623         if (printed)
 624                 printf("\n");
 625 }
 626
 627 static void add_reloc(struct relocs *r, uint32_t offset)
 628 {
 629         if (r->count == r->size) {
 630                 unsigned long newsize = r->size + 50000;
 631                 void *mem = realloc(r->offset, newsize * sizeof(r->offset[0]));
 632
 633                 if (!mem)
 634                         die("realloc of %ld entries for relocs failed\n",
 635                                 newsize);
 636                 r->offset = mem;
 637                 r->size = newsize;
 638         }
 639         r->offset[r->count++] = offset;
 640 }
 641
 642 static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
 643                         Elf_Sym *sym, const char *symname))
 644 {
 645         int i;
 646         /* Walk through the relocations */
 647         for (i = 0; i < ehdr.e_shnum; i++) {
 648                 char *sym_strtab;
 649                 Elf_Sym *sh_symtab;
 650                 struct section *sec_applies, *sec_symtab;
 651                 int j;
 652                 struct section *sec = &secs[i];
 653
 654                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 655                         continue;
 656                 }
 657                 sec_symtab  = sec->link;
 658                 sec_applies = &secs[sec->shdr.sh_info];
 659                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 660                         continue;
 661                 }
 662                 sh_symtab = sec_symtab->symtab;
 663                 sym_strtab = sec_symtab->link->strtab;
 664                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 665                         Elf_Rel *rel = &sec->reltab[j];
 666                         Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
 667                         const char *symname = sym_name(sym_strtab, sym);
 668
 669                         process(sec, rel, sym, symname);
 670                 }
 671         }
 672 }
 673
 674 /*
 675  * The .data..percpu section is a special case for x86_64 SMP kernels.
 676  * It is used to initialize the actual per_cpu areas and to provide
 677  * definitions for the per_cpu variables that correspond to their offsets
 678  * within the percpu area. Since the values of all of the symbols need
 679  * to be offsets from the start of the per_cpu area the virtual address
 680  * (sh_addr) of .data..percpu is 0 in SMP kernels.
 681  *
 682  * This means that:
 683  *
 684  *      Relocations that reference symbols in the per_cpu area do not
 685  *      need further relocation (since the value is an offset relative
 686  *      to the start of the per_cpu area that does not change).
 687  *
 688  *      Relocations that apply to the per_cpu area need to have their
 689  *      offset adjusted by by the value of __per_cpu_load to make them
 690  *      point to the correct place in the loaded image (because the
 691  *      virtual address of .data..percpu is 0).
 692  *
 693  * For non SMP kernels .data..percpu is linked as part of the normal
 694  * kernel data and does not require special treatment.
 695  *
 696  */
 697 static int per_cpu_shndx        = -1;
 698 Elf_Addr per_cpu_load_addr;
 699
 700 static void percpu_init(void)
 701 {
 702         int i;
 703         for (i = 0; i < ehdr.e_shnum; i++) {
 704                 ElfW(Sym) *sym;
 705                 if (strcmp(sec_name(i), ".data..percpu"))
 706                         continue;
 707
 708                 if (secs[i].shdr.sh_addr != 0)  /* non SMP kernel */
 709                         return;
 710
 711                 sym = sym_lookup("__per_cpu_load");
 712                 if (!sym)
 713                         die("can't find __per_cpu_load\n");
 714
 715                 per_cpu_shndx = i;
 716                 per_cpu_load_addr = sym->st_value;
 717                 return;
 718         }
 719 }
 720
 721 #if ELF_BITS == 64
 722
 723 /*
 724  * Check to see if a symbol lies in the .data..percpu section.
 725  *
 726  * The linker incorrectly associates some symbols with the
 727  * .data..percpu section so we also need to check the symbol
 728  * name to make sure that we classify the symbol correctly.
 729  *
 730  * The GNU linker incorrectly associates:
 731  *      __init_begin
 732  *      __per_cpu_load
 733  *
 734  * The "gold" linker incorrectly associates:
 735  *      init_per_cpu__irq_stack_union
 736  *      init_per_cpu__gdt_page
 737  */
 738 static int is_percpu_sym(ElfW(Sym) *sym, const char *symname)
 739 {
 740         return (sym->st_shndx == per_cpu_shndx) &&
 741                 strcmp(symname, "__init_begin") &&
 742                 strcmp(symname, "__per_cpu_load") &&
 743                 strncmp(symname, "init_per_cpu_", 13);
 744 }
 745
 746
 747 static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
 748                       const char *symname)
 749 {
 750         unsigned r_type = ELF64_R_TYPE(rel->r_info);
 751         ElfW(Addr) offset = rel->r_offset;
 752         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 753
 754         if (sym->st_shndx == SHN_UNDEF)
 755                 return 0;
 756
 757         /*
 758          * Adjust the offset if this reloc applies to the percpu section.
 759          */
 760         if (sec->shdr.sh_info == per_cpu_shndx)
 761                 offset += per_cpu_load_addr;
 762
 763         switch (r_type) {
 764         case R_X86_64_NONE:
 765         case R_X86_64_PC32:
 766                 /*
 767                  * NONE can be ignored and PC relative relocations don't
 768                  * need to be adjusted.
 769                  */
 770                 break;
 771
 772         case R_X86_64_32:
 773         case R_X86_64_32S:
 774         case R_X86_64_64:
 775                 /*
 776                  * References to the percpu area don't need to be adjusted.
 777                  */
 778                 if (is_percpu_sym(sym, symname))
 779                         break;
 780
 781                 if (shn_abs) {
 782                         /*
 783                          * Whitelisted absolute symbols do not require
 784                          * relocation.
 785                          */
 786                         if (is_reloc(S_ABS, symname))
 787                                 break;
 788
 789                         die("Invalid absolute %s relocation: %s\n",
 790                             rel_type(r_type), symname);
 791                         break;
 792                 }
 793
 794                 /*
 795                  * Relocation offsets for 64 bit kernels are output
 796                  * as 32 bits and sign extended back to 64 bits when
 797                  * the relocations are processed.
 798                  * Make sure that the offset will fit.
 799                  */
 800                 if ((int32_t)offset != (int64_t)offset)
 801                         die("Relocation offset doesn't fit in 32 bits\n");
 802
 803                 if (r_type == R_X86_64_64)
 804                         add_reloc(&relocs64, offset);
 805                 else
 806                         add_reloc(&relocs32, offset);
 807                 break;
 808
 809         default:
 810                 die("Unsupported relocation type: %s (%d)\n",
 811                     rel_type(r_type), r_type);
 812                 break;
 813         }
 814
 815         return 0;
 816 }
 817
 818 #else
 819
 820 static int do_reloc32(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 821                       const char *symname)
 822 {
 823         unsigned r_type = ELF32_R_TYPE(rel->r_info);
 824         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 825
 826         switch (r_type) {
 827         case R_386_NONE:
 828         case R_386_PC32:
 829         case R_386_PC16:
 830         case R_386_PC8:
 831                 /*
 832                  * NONE can be ignored and PC relative relocations don't
 833                  * need to be adjusted.
 834                  */
 835                 break;
 836
 837         case R_386_32:
 838                 if (shn_abs) {
 839                         /*
 840                          * Whitelisted absolute symbols do not require
 841                          * relocation.
 842                          */
 843                         if (is_reloc(S_ABS, symname))
 844                                 break;
 845
 846                         die("Invalid absolute %s relocation: %s\n",
 847                             rel_type(r_type), symname);
 848                         break;
 849                 }
 850
 851                 add_reloc(&relocs32, rel->r_offset);
 852                 break;
 853
 854         default:
 855                 die("Unsupported relocation type: %s (%d)\n",
 856                     rel_type(r_type), r_type);
 857                 break;
 858         }
 859
 860         return 0;
 861 }
 862
 863 static int do_reloc_real(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 864                          const char *symname)
 865 {
 866         unsigned r_type = ELF32_R_TYPE(rel->r_info);
 867         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 868
 869         switch (r_type) {
 870         case R_386_NONE:
 871         case R_386_PC32:
 872         case R_386_PC16:
 873         case R_386_PC8:
 874                 /*
 875                  * NONE can be ignored and PC relative relocations don't
 876                  * need to be adjusted.
 877                  */
 878                 break;
 879
 880         case R_386_16:
 881                 if (shn_abs) {
 882                         /*
 883                          * Whitelisted absolute symbols do not require
 884                          * relocation.
 885                          */
 886                         if (is_reloc(S_ABS, symname))
 887                                 break;
 888
 889                         if (is_reloc(S_SEG, symname)) {
 890                                 add_reloc(&relocs16, rel->r_offset);
 891                                 break;
 892                         }
 893                 } else {
 894                         if (!is_reloc(S_LIN, symname))
 895                                 break;
 896                 }
 897                 die("Invalid %s %s relocation: %s\n",
 898                     shn_abs ? "absolute" : "relative",
 899                     rel_type(r_type), symname);
 900                 break;
 901
 902         case R_386_32:
 903                 if (shn_abs) {
 904                         /*
 905                          * Whitelisted absolute symbols do not require
 906                          * relocation.
 907                          */
 908                         if (is_reloc(S_ABS, symname))
 909                                 break;
 910
 911                         if (is_reloc(S_REL, symname)) {
 912                                 add_reloc(&relocs32, rel->r_offset);
 913                                 break;
 914                         }
 915                 } else {
 916                         if (is_reloc(S_LIN, symname))
 917                                 add_reloc(&relocs32, rel->r_offset);
 918                         break;
 919                 }
 920                 die("Invalid %s %s relocation: %s\n",
 921                     shn_abs ? "absolute" : "relative",
 922                     rel_type(r_type), symname);
 923                 break;
 924
 925         default:
 926                 die("Unsupported relocation type: %s (%d)\n",
 927                     rel_type(r_type), r_type);
 928                 break;
 929         }
 930
 931         return 0;
 932 }
 933
 934 #endif
 935
 936 static int cmp_relocs(const void *va, const void *vb)
 937 {
 938         const uint32_t *a, *b;
 939         a = va; b = vb;
 940         return (*a == *b)? 0 : (*a > *b)? 1 : -1;
 941 }
 942
 943 static void sort_relocs(struct relocs *r)
 944 {
 945         qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
 946 }
 947
 948 static int write32(uint32_t v, FILE *f)
 949 {
 950         unsigned char buf[4];
 951
 952         put_unaligned_le32(v, buf);
 953         return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
 954 }
 955
 956 static int write32_as_text(uint32_t v, FILE *f)
 957 {
 958         return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
 959 }
 960
 961 static void emit_relocs(int as_text, int use_real_mode)
 962 {
 963         int i;
 964         int (*write_reloc)(uint32_t, FILE *) = write32;
 965         int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 966                         const char *symname);
 967
 968 #if ELF_BITS == 64
 969         if (!use_real_mode)
 970                 do_reloc = do_reloc64;
 971         else
 972                 die("--realmode not valid for a 64-bit ELF file");
 973 #else
 974         if (!use_real_mode)
 975                 do_reloc = do_reloc32;
 976         else
 977                 do_reloc = do_reloc_real;
 978 #endif
 979
 980         /* Collect up the relocations */
 981         walk_relocs(do_reloc);
 982
 983         if (relocs16.count && !use_real_mode)
 984                 die("Segment relocations found but --realmode not specified\n");
 985
 986         /* Order the relocations for more efficient processing */
 987         sort_relocs(&relocs16);
 988         sort_relocs(&relocs32);
 989         sort_relocs(&relocs64);
 990
 991         /* Print the relocations */
 992         if (as_text) {
 993                 /* Print the relocations in a form suitable that
 994                  * gas will like.
 995                  */
 996                 printf(".section \".data.reloc\",\"a\"\n");
 997                 printf(".balign 4\n");
 998                 write_reloc = write32_as_text;
 999         }
1000
1001         if (use_real_mode) {
1002                 write_reloc(relocs16.count, stdout);
1003                 for (i = 0; i < relocs16.count; i++)
1004                         write_reloc(relocs16.offset[i], stdout);
1005
1006                 write_reloc(relocs32.count, stdout);
1007                 for (i = 0; i < relocs32.count; i++)
1008                         write_reloc(relocs32.offset[i], stdout);
1009         } else {
1010                 if (ELF_BITS == 64) {
1011                         /* Print a stop */
1012                         write_reloc(0, stdout);
1013
1014                         /* Now print each relocation */
1015                         for (i = 0; i < relocs64.count; i++)
1016                                 write_reloc(relocs64.offset[i], stdout);
1017                 }
1018
1019                 /* Print a stop */
1020                 write_reloc(0, stdout);
1021
1022                 /* Now print each relocation */
1023                 for (i = 0; i < relocs32.count; i++)
1024                         write_reloc(relocs32.offset[i], stdout);
1025         }
1026 }
1027
1028 /*
1029  * As an aid to debugging problems with different linkers
1030  * print summary information about the relocs.
1031  * Since different linkers tend to emit the sections in
1032  * different orders we use the section names in the output.
1033  */
1034 static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
1035                                 const char *symname)
1036 {
1037         printf("%s\t%s\t%s\t%s\n",
1038                 sec_name(sec->shdr.sh_info),
1039                 rel_type(ELF_R_TYPE(rel->r_info)),
1040                 symname,
1041                 sec_name(sym->st_shndx));
1042         return 0;
1043 }
1044
1045 static void print_reloc_info(void)
1046 {
1047         printf("reloc section\treloc type\tsymbol\tsymbol section\n");
1048         walk_relocs(do_reloc_info);
1049 }
1050
1051 #if ELF_BITS == 64
1052 # define process process_64
1053 #else
1054 # define process process_32
1055 #endif
1056
1057 void process(FILE *fp, int use_real_mode, int as_text,
1058              int show_absolute_syms, int show_absolute_relocs,
1059              int show_reloc_info)
1060 {
1061         regex_init(use_real_mode);
1062         read_ehdr(fp);
1063         read_shdrs(fp);
1064         read_strtabs(fp);
1065         read_symtabs(fp);
1066         read_relocs(fp);
1067         if (ELF_BITS == 64)
1068                 percpu_init();
1069         if (show_absolute_syms) {
1070                 print_absolute_symbols();
1071                 return;
1072         }
1073         if (show_absolute_relocs) {
1074                 print_absolute_relocs();
1075                 return;
1076         }
1077         if (show_reloc_info) {
1078                 print_reloc_info();
1079                 return;
1080         }
1081         emit_relocs(as_text, use_real_mode);
1082 }