arch/x86/tools/relocs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* This is included from relocs_32/64.c */
   3
   4 #define ElfW(type)              _ElfW(ELF_BITS, type)
   5 #define _ElfW(bits, type)       __ElfW(bits, type)
   6 #define __ElfW(bits, type)      Elf##bits##_##type
   7
   8 #define Elf_Addr                ElfW(Addr)
   9 #define Elf_Ehdr                ElfW(Ehdr)
  10 #define Elf_Phdr                ElfW(Phdr)
  11 #define Elf_Shdr                ElfW(Shdr)
  12 #define Elf_Sym                 ElfW(Sym)
  13
  14 static Elf_Ehdr ehdr;
  15
  16 struct relocs {
  17         uint32_t        *offset;
  18         unsigned long   count;
  19         unsigned long   size;
  20 };
  21
  22 static struct relocs relocs16;
  23 static struct relocs relocs32;
  24 #if ELF_BITS == 64
  25 static struct relocs relocs32neg;
  26 static struct relocs relocs64;
  27 #endif
  28
  29 struct section {
  30         Elf_Shdr       shdr;
  31         struct section *link;
  32         Elf_Sym        *symtab;
  33         Elf_Rel        *reltab;
  34         char           *strtab;
  35 };
  36 static struct section *secs;
  37
  38 static const char * const sym_regex_kernel[S_NSYMTYPES] = {
  39 /*
  40  * Following symbols have been audited. There values are constant and do
  41  * not change if bzImage is loaded at a different physical address than
  42  * the address for which it has been compiled. Don't warn user about
  43  * absolute relocations present w.r.t these symbols.
  44  */
  45         [S_ABS] =
  46         "^(xen_irq_disable_direct_reloc$|"
  47         "xen_save_fl_direct_reloc$|"
  48         "VDSO|"
  49         "__crc_)",
  50
  51 /*
  52  * These symbols are known to be relative, even if the linker marks them
  53  * as absolute (typically defined outside any section in the linker script.)
  54  */
  55         [S_REL] =
  56         "^(__init_(begin|end)|"
  57         "__x86_cpu_dev_(start|end)|"
  58         "(__parainstructions|__alt_instructions)(|_end)|"
  59         "(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
  60         "__(start|end)_pci_.*|"
  61         "__(start|end)_builtin_fw|"
  62         "__(start|stop)___ksymtab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
  63         "__(start|stop)___kcrctab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
  64         "__(start|stop)___param|"
  65         "__(start|stop)___modver|"
  66         "__(start|stop)___bug_table|"
  67         "__tracedata_(start|end)|"
  68         "__(start|stop)_notes|"
  69         "__end_rodata|"
  70         "__initramfs_start|"
  71         "(jiffies|jiffies_64)|"
  72 #if ELF_BITS == 64
  73         "__per_cpu_load|"
  74         "init_per_cpu__.*|"
  75         "__end_rodata_hpage_align|"
  76 #endif
  77         "__vvar_page|"
  78         "_end)$"
  79 };
  80
  81
  82 static const char * const sym_regex_realmode[S_NSYMTYPES] = {
  83 /*
  84  * These symbols are known to be relative, even if the linker marks them
  85  * as absolute (typically defined outside any section in the linker script.)
  86  */
  87         [S_REL] =
  88         "^pa_",
  89
  90 /*
  91  * These are 16-bit segment symbols when compiling 16-bit code.
  92  */
  93         [S_SEG] =
  94         "^real_mode_seg$",
  95
  96 /*
  97  * These are offsets belonging to segments, as opposed to linear addresses,
  98  * when compiling 16-bit code.
  99  */
 100         [S_LIN] =
 101         "^pa_",
 102 };
 103
 104 static const char * const *sym_regex;
 105
 106 static regex_t sym_regex_c[S_NSYMTYPES];
 107 static int is_reloc(enum symtype type, const char *sym_name)
 108 {
 109         return sym_regex[type] &&
 110                 !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
 111 }
 112
 113 static void regex_init(int use_real_mode)
 114 {
 115         char errbuf[128];
 116         int err;
 117         int i;
 118
 119         if (use_real_mode)
 120                 sym_regex = sym_regex_realmode;
 121         else
 122                 sym_regex = sym_regex_kernel;
 123
 124         for (i = 0; i < S_NSYMTYPES; i++) {
 125                 if (!sym_regex[i])
 126                         continue;
 127
 128                 err = regcomp(&sym_regex_c[i], sym_regex[i],
 129                               REG_EXTENDED|REG_NOSUB);
 130
 131                 if (err) {
 132                         regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
 133                         die("%s", errbuf);
 134                 }
 135         }
 136 }
 137
 138 static const char *sym_type(unsigned type)
 139 {
 140         static const char *type_name[] = {
 141 #define SYM_TYPE(X) [X] = #X
 142                 SYM_TYPE(STT_NOTYPE),
 143                 SYM_TYPE(STT_OBJECT),
 144                 SYM_TYPE(STT_FUNC),
 145                 SYM_TYPE(STT_SECTION),
 146                 SYM_TYPE(STT_FILE),
 147                 SYM_TYPE(STT_COMMON),
 148                 SYM_TYPE(STT_TLS),
 149 #undef SYM_TYPE
 150         };
 151         const char *name = "unknown sym type name";
 152         if (type < ARRAY_SIZE(type_name)) {
 153                 name = type_name[type];
 154         }
 155         return name;
 156 }
 157
 158 static const char *sym_bind(unsigned bind)
 159 {
 160         static const char *bind_name[] = {
 161 #define SYM_BIND(X) [X] = #X
 162                 SYM_BIND(STB_LOCAL),
 163                 SYM_BIND(STB_GLOBAL),
 164                 SYM_BIND(STB_WEAK),
 165 #undef SYM_BIND
 166         };
 167         const char *name = "unknown sym bind name";
 168         if (bind < ARRAY_SIZE(bind_name)) {
 169                 name = bind_name[bind];
 170         }
 171         return name;
 172 }
 173
 174 static const char *sym_visibility(unsigned visibility)
 175 {
 176         static const char *visibility_name[] = {
 177 #define SYM_VISIBILITY(X) [X] = #X
 178                 SYM_VISIBILITY(STV_DEFAULT),
 179                 SYM_VISIBILITY(STV_INTERNAL),
 180                 SYM_VISIBILITY(STV_HIDDEN),
 181                 SYM_VISIBILITY(STV_PROTECTED),
 182 #undef SYM_VISIBILITY
 183         };
 184         const char *name = "unknown sym visibility name";
 185         if (visibility < ARRAY_SIZE(visibility_name)) {
 186                 name = visibility_name[visibility];
 187         }
 188         return name;
 189 }
 190
 191 static const char *rel_type(unsigned type)
 192 {
 193         static const char *type_name[] = {
 194 #define REL_TYPE(X) [X] = #X
 195 #if ELF_BITS == 64
 196                 REL_TYPE(R_X86_64_NONE),
 197                 REL_TYPE(R_X86_64_64),
 198                 REL_TYPE(R_X86_64_PC32),
 199                 REL_TYPE(R_X86_64_GOT32),
 200                 REL_TYPE(R_X86_64_PLT32),
 201                 REL_TYPE(R_X86_64_COPY),
 202                 REL_TYPE(R_X86_64_GLOB_DAT),
 203                 REL_TYPE(R_X86_64_JUMP_SLOT),
 204                 REL_TYPE(R_X86_64_RELATIVE),
 205                 REL_TYPE(R_X86_64_GOTPCREL),
 206                 REL_TYPE(R_X86_64_32),
 207                 REL_TYPE(R_X86_64_32S),
 208                 REL_TYPE(R_X86_64_16),
 209                 REL_TYPE(R_X86_64_PC16),
 210                 REL_TYPE(R_X86_64_8),
 211                 REL_TYPE(R_X86_64_PC8),
 212 #else
 213                 REL_TYPE(R_386_NONE),
 214                 REL_TYPE(R_386_32),
 215                 REL_TYPE(R_386_PC32),
 216                 REL_TYPE(R_386_GOT32),
 217                 REL_TYPE(R_386_PLT32),
 218                 REL_TYPE(R_386_COPY),
 219                 REL_TYPE(R_386_GLOB_DAT),
 220                 REL_TYPE(R_386_JMP_SLOT),
 221                 REL_TYPE(R_386_RELATIVE),
 222                 REL_TYPE(R_386_GOTOFF),
 223                 REL_TYPE(R_386_GOTPC),
 224                 REL_TYPE(R_386_8),
 225                 REL_TYPE(R_386_PC8),
 226                 REL_TYPE(R_386_16),
 227                 REL_TYPE(R_386_PC16),
 228 #endif
 229 #undef REL_TYPE
 230         };
 231         const char *name = "unknown type rel type name";
 232         if (type < ARRAY_SIZE(type_name) && type_name[type]) {
 233                 name = type_name[type];
 234         }
 235         return name;
 236 }
 237
 238 static const char *sec_name(unsigned shndx)
 239 {
 240         const char *sec_strtab;
 241         const char *name;
 242         sec_strtab = secs[ehdr.e_shstrndx].strtab;
 243         name = "<noname>";
 244         if (shndx < ehdr.e_shnum) {
 245                 name = sec_strtab + secs[shndx].shdr.sh_name;
 246         }
 247         else if (shndx == SHN_ABS) {
 248                 name = "ABSOLUTE";
 249         }
 250         else if (shndx == SHN_COMMON) {
 251                 name = "COMMON";
 252         }
 253         return name;
 254 }
 255
 256 static const char *sym_name(const char *sym_strtab, Elf_Sym *sym)
 257 {
 258         const char *name;
 259         name = "<noname>";
 260         if (sym->st_name) {
 261                 name = sym_strtab + sym->st_name;
 262         }
 263         else {
 264                 name = sec_name(sym->st_shndx);
 265         }
 266         return name;
 267 }
 268
 269 static Elf_Sym *sym_lookup(const char *symname)
 270 {
 271         int i;
 272         for (i = 0; i < ehdr.e_shnum; i++) {
 273                 struct section *sec = &secs[i];
 274                 long nsyms;
 275                 char *strtab;
 276                 Elf_Sym *symtab;
 277                 Elf_Sym *sym;
 278
 279                 if (sec->shdr.sh_type != SHT_SYMTAB)
 280                         continue;
 281
 282                 nsyms = sec->shdr.sh_size/sizeof(Elf_Sym);
 283                 symtab = sec->symtab;
 284                 strtab = sec->link->strtab;
 285
 286                 for (sym = symtab; --nsyms >= 0; sym++) {
 287                         if (!sym->st_name)
 288                                 continue;
 289                         if (strcmp(symname, strtab + sym->st_name) == 0)
 290                                 return sym;
 291                 }
 292         }
 293         return 0;
 294 }
 295
 296 #if BYTE_ORDER == LITTLE_ENDIAN
 297 #define le16_to_cpu(val) (val)
 298 #define le32_to_cpu(val) (val)
 299 #define le64_to_cpu(val) (val)
 300 #endif
 301 #if BYTE_ORDER == BIG_ENDIAN
 302 #define le16_to_cpu(val) bswap_16(val)
 303 #define le32_to_cpu(val) bswap_32(val)
 304 #define le64_to_cpu(val) bswap_64(val)
 305 #endif
 306
 307 static uint16_t elf16_to_cpu(uint16_t val)
 308 {
 309         return le16_to_cpu(val);
 310 }
 311
 312 static uint32_t elf32_to_cpu(uint32_t val)
 313 {
 314         return le32_to_cpu(val);
 315 }
 316
 317 #define elf_half_to_cpu(x)      elf16_to_cpu(x)
 318 #define elf_word_to_cpu(x)      elf32_to_cpu(x)
 319
 320 #if ELF_BITS == 64
 321 static uint64_t elf64_to_cpu(uint64_t val)
 322 {
 323         return le64_to_cpu(val);
 324 }
 325 #define elf_addr_to_cpu(x)      elf64_to_cpu(x)
 326 #define elf_off_to_cpu(x)       elf64_to_cpu(x)
 327 #define elf_xword_to_cpu(x)     elf64_to_cpu(x)
 328 #else
 329 #define elf_addr_to_cpu(x)      elf32_to_cpu(x)
 330 #define elf_off_to_cpu(x)       elf32_to_cpu(x)
 331 #define elf_xword_to_cpu(x)     elf32_to_cpu(x)
 332 #endif
 333
 334 static void read_ehdr(FILE *fp)
 335 {
 336         if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
 337                 die("Cannot read ELF header: %s\n",
 338                         strerror(errno));
 339         }
 340         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
 341                 die("No ELF magic\n");
 342         }
 343         if (ehdr.e_ident[EI_CLASS] != ELF_CLASS) {
 344                 die("Not a %d bit executable\n", ELF_BITS);
 345         }
 346         if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
 347                 die("Not a LSB ELF executable\n");
 348         }
 349         if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
 350                 die("Unknown ELF version\n");
 351         }
 352         /* Convert the fields to native endian */
 353         ehdr.e_type      = elf_half_to_cpu(ehdr.e_type);
 354         ehdr.e_machine   = elf_half_to_cpu(ehdr.e_machine);
 355         ehdr.e_version   = elf_word_to_cpu(ehdr.e_version);
 356         ehdr.e_entry     = elf_addr_to_cpu(ehdr.e_entry);
 357         ehdr.e_phoff     = elf_off_to_cpu(ehdr.e_phoff);
 358         ehdr.e_shoff     = elf_off_to_cpu(ehdr.e_shoff);
 359         ehdr.e_flags     = elf_word_to_cpu(ehdr.e_flags);
 360         ehdr.e_ehsize    = elf_half_to_cpu(ehdr.e_ehsize);
 361         ehdr.e_phentsize = elf_half_to_cpu(ehdr.e_phentsize);
 362         ehdr.e_phnum     = elf_half_to_cpu(ehdr.e_phnum);
 363         ehdr.e_shentsize = elf_half_to_cpu(ehdr.e_shentsize);
 364         ehdr.e_shnum     = elf_half_to_cpu(ehdr.e_shnum);
 365         ehdr.e_shstrndx  = elf_half_to_cpu(ehdr.e_shstrndx);
 366
 367         if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
 368                 die("Unsupported ELF header type\n");
 369         }
 370         if (ehdr.e_machine != ELF_MACHINE) {
 371                 die("Not for %s\n", ELF_MACHINE_NAME);
 372         }
 373         if (ehdr.e_version != EV_CURRENT) {
 374                 die("Unknown ELF version\n");
 375         }
 376         if (ehdr.e_ehsize != sizeof(Elf_Ehdr)) {
 377                 die("Bad Elf header size\n");
 378         }
 379         if (ehdr.e_phentsize != sizeof(Elf_Phdr)) {
 380                 die("Bad program header entry\n");
 381         }
 382         if (ehdr.e_shentsize != sizeof(Elf_Shdr)) {
 383                 die("Bad section header entry\n");
 384         }
 385         if (ehdr.e_shstrndx >= ehdr.e_shnum) {
 386                 die("String table index out of bounds\n");
 387         }
 388 }
 389
 390 static void read_shdrs(FILE *fp)
 391 {
 392         int i;
 393         Elf_Shdr shdr;
 394
 395         secs = calloc(ehdr.e_shnum, sizeof(struct section));
 396         if (!secs) {
 397                 die("Unable to allocate %d section headers\n",
 398                     ehdr.e_shnum);
 399         }
 400         if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
 401                 die("Seek to %d failed: %s\n",
 402                         ehdr.e_shoff, strerror(errno));
 403         }
 404         for (i = 0; i < ehdr.e_shnum; i++) {
 405                 struct section *sec = &secs[i];
 406                 if (fread(&shdr, sizeof shdr, 1, fp) != 1)
 407                         die("Cannot read ELF section headers %d/%d: %s\n",
 408                             i, ehdr.e_shnum, strerror(errno));
 409                 sec->shdr.sh_name      = elf_word_to_cpu(shdr.sh_name);
 410                 sec->shdr.sh_type      = elf_word_to_cpu(shdr.sh_type);
 411                 sec->shdr.sh_flags     = elf_xword_to_cpu(shdr.sh_flags);
 412                 sec->shdr.sh_addr      = elf_addr_to_cpu(shdr.sh_addr);
 413                 sec->shdr.sh_offset    = elf_off_to_cpu(shdr.sh_offset);
 414                 sec->shdr.sh_size      = elf_xword_to_cpu(shdr.sh_size);
 415                 sec->shdr.sh_link      = elf_word_to_cpu(shdr.sh_link);
 416                 sec->shdr.sh_info      = elf_word_to_cpu(shdr.sh_info);
 417                 sec->shdr.sh_addralign = elf_xword_to_cpu(shdr.sh_addralign);
 418                 sec->shdr.sh_entsize   = elf_xword_to_cpu(shdr.sh_entsize);
 419                 if (sec->shdr.sh_link < ehdr.e_shnum)
 420                         sec->link = &secs[sec->shdr.sh_link];
 421         }
 422
 423 }
 424
 425 static void read_strtabs(FILE *fp)
 426 {
 427         int i;
 428         for (i = 0; i < ehdr.e_shnum; i++) {
 429                 struct section *sec = &secs[i];
 430                 if (sec->shdr.sh_type != SHT_STRTAB) {
 431                         continue;
 432                 }
 433                 sec->strtab = malloc(sec->shdr.sh_size);
 434                 if (!sec->strtab) {
 435                         die("malloc of %d bytes for strtab failed\n",
 436                                 sec->shdr.sh_size);
 437                 }
 438                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 439                         die("Seek to %d failed: %s\n",
 440                                 sec->shdr.sh_offset, strerror(errno));
 441                 }
 442                 if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
 443                     != sec->shdr.sh_size) {
 444                         die("Cannot read symbol table: %s\n",
 445                                 strerror(errno));
 446                 }
 447         }
 448 }
 449
 450 static void read_symtabs(FILE *fp)
 451 {
 452         int i,j;
 453         for (i = 0; i < ehdr.e_shnum; i++) {
 454                 struct section *sec = &secs[i];
 455                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 456                         continue;
 457                 }
 458                 sec->symtab = malloc(sec->shdr.sh_size);
 459                 if (!sec->symtab) {
 460                         die("malloc of %d bytes for symtab failed\n",
 461                                 sec->shdr.sh_size);
 462                 }
 463                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 464                         die("Seek to %d failed: %s\n",
 465                                 sec->shdr.sh_offset, strerror(errno));
 466                 }
 467                 if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
 468                     != sec->shdr.sh_size) {
 469                         die("Cannot read symbol table: %s\n",
 470                                 strerror(errno));
 471                 }
 472                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
 473                         Elf_Sym *sym = &sec->symtab[j];
 474                         sym->st_name  = elf_word_to_cpu(sym->st_name);
 475                         sym->st_value = elf_addr_to_cpu(sym->st_value);
 476                         sym->st_size  = elf_xword_to_cpu(sym->st_size);
 477                         sym->st_shndx = elf_half_to_cpu(sym->st_shndx);
 478                 }
 479         }
 480 }
 481
 482
 483 static void read_relocs(FILE *fp)
 484 {
 485         int i,j;
 486         for (i = 0; i < ehdr.e_shnum; i++) {
 487                 struct section *sec = &secs[i];
 488                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 489                         continue;
 490                 }
 491                 sec->reltab = malloc(sec->shdr.sh_size);
 492                 if (!sec->reltab) {
 493                         die("malloc of %d bytes for relocs failed\n",
 494                                 sec->shdr.sh_size);
 495                 }
 496                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 497                         die("Seek to %d failed: %s\n",
 498                                 sec->shdr.sh_offset, strerror(errno));
 499                 }
 500                 if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
 501                     != sec->shdr.sh_size) {
 502                         die("Cannot read symbol table: %s\n",
 503                                 strerror(errno));
 504                 }
 505                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 506                         Elf_Rel *rel = &sec->reltab[j];
 507                         rel->r_offset = elf_addr_to_cpu(rel->r_offset);
 508                         rel->r_info   = elf_xword_to_cpu(rel->r_info);
 509 #if (SHT_REL_TYPE == SHT_RELA)
 510                         rel->r_addend = elf_xword_to_cpu(rel->r_addend);
 511 #endif
 512                 }
 513         }
 514 }
 515
 516
 517 static void print_absolute_symbols(void)
 518 {
 519         int i;
 520         const char *format;
 521
 522         if (ELF_BITS == 64)
 523                 format = "%5d %016"PRIx64" %5"PRId64" %10s %10s %12s %s\n";
 524         else
 525                 format = "%5d %08"PRIx32"  %5"PRId32" %10s %10s %12s %s\n";
 526
 527         printf("Absolute symbols\n");
 528         printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
 529         for (i = 0; i < ehdr.e_shnum; i++) {
 530                 struct section *sec = &secs[i];
 531                 char *sym_strtab;
 532                 int j;
 533
 534                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 535                         continue;
 536                 }
 537                 sym_strtab = sec->link->strtab;
 538                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
 539                         Elf_Sym *sym;
 540                         const char *name;
 541                         sym = &sec->symtab[j];
 542                         name = sym_name(sym_strtab, sym);
 543                         if (sym->st_shndx != SHN_ABS) {
 544                                 continue;
 545                         }
 546                         printf(format,
 547                                 j, sym->st_value, sym->st_size,
 548                                 sym_type(ELF_ST_TYPE(sym->st_info)),
 549                                 sym_bind(ELF_ST_BIND(sym->st_info)),
 550                                 sym_visibility(ELF_ST_VISIBILITY(sym->st_other)),
 551                                 name);
 552                 }
 553         }
 554         printf("\n");
 555 }
 556
 557 static void print_absolute_relocs(void)
 558 {
 559         int i, printed = 0;
 560         const char *format;
 561
 562         if (ELF_BITS == 64)
 563                 format = "%016"PRIx64" %016"PRIx64" %10s %016"PRIx64"  %s\n";
 564         else
 565                 format = "%08"PRIx32" %08"PRIx32" %10s %08"PRIx32"  %s\n";
 566
 567         for (i = 0; i < ehdr.e_shnum; i++) {
 568                 struct section *sec = &secs[i];
 569                 struct section *sec_applies, *sec_symtab;
 570                 char *sym_strtab;
 571                 Elf_Sym *sh_symtab;
 572                 int j;
 573                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 574                         continue;
 575                 }
 576                 sec_symtab  = sec->link;
 577                 sec_applies = &secs[sec->shdr.sh_info];
 578                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 579                         continue;
 580                 }
 581                 sh_symtab  = sec_symtab->symtab;
 582                 sym_strtab = sec_symtab->link->strtab;
 583                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 584                         Elf_Rel *rel;
 585                         Elf_Sym *sym;
 586                         const char *name;
 587                         rel = &sec->reltab[j];
 588                         sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
 589                         name = sym_name(sym_strtab, sym);
 590                         if (sym->st_shndx != SHN_ABS) {
 591                                 continue;
 592                         }
 593
 594                         /* Absolute symbols are not relocated if bzImage is
 595                          * loaded at a non-compiled address. Display a warning
 596                          * to user at compile time about the absolute
 597                          * relocations present.
 598                          *
 599                          * User need to audit the code to make sure
 600                          * some symbols which should have been section
 601                          * relative have not become absolute because of some
 602                          * linker optimization or wrong programming usage.
 603                          *
 604                          * Before warning check if this absolute symbol
 605                          * relocation is harmless.
 606                          */
 607                         if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
 608                                 continue;
 609
 610                         if (!printed) {
 611                                 printf("WARNING: Absolute relocations"
 612                                         " present\n");
 613                                 printf("Offset     Info     Type     Sym.Value "
 614                                         "Sym.Name\n");
 615                                 printed = 1;
 616                         }
 617
 618                         printf(format,
 619                                 rel->r_offset,
 620                                 rel->r_info,
 621                                 rel_type(ELF_R_TYPE(rel->r_info)),
 622                                 sym->st_value,
 623                                 name);
 624                 }
 625         }
 626
 627         if (printed)
 628                 printf("\n");
 629 }
 630
 631 static void add_reloc(struct relocs *r, uint32_t offset)
 632 {
 633         if (r->count == r->size) {
 634                 unsigned long newsize = r->size + 50000;
 635                 void *mem = realloc(r->offset, newsize * sizeof(r->offset[0]));
 636
 637                 if (!mem)
 638                         die("realloc of %ld entries for relocs failed\n",
 639                                 newsize);
 640                 r->offset = mem;
 641                 r->size = newsize;
 642         }
 643         r->offset[r->count++] = offset;
 644 }
 645
 646 static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
 647                         Elf_Sym *sym, const char *symname))
 648 {
 649         int i;
 650         /* Walk through the relocations */
 651         for (i = 0; i < ehdr.e_shnum; i++) {
 652                 char *sym_strtab;
 653                 Elf_Sym *sh_symtab;
 654                 struct section *sec_applies, *sec_symtab;
 655                 int j;
 656                 struct section *sec = &secs[i];
 657
 658                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 659                         continue;
 660                 }
 661                 sec_symtab  = sec->link;
 662                 sec_applies = &secs[sec->shdr.sh_info];
 663                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 664                         continue;
 665                 }
 666                 sh_symtab = sec_symtab->symtab;
 667                 sym_strtab = sec_symtab->link->strtab;
 668                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 669                         Elf_Rel *rel = &sec->reltab[j];
 670                         Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
 671                         const char *symname = sym_name(sym_strtab, sym);
 672
 673                         process(sec, rel, sym, symname);
 674                 }
 675         }
 676 }
 677
 678 /*
 679  * The .data..percpu section is a special case for x86_64 SMP kernels.
 680  * It is used to initialize the actual per_cpu areas and to provide
 681  * definitions for the per_cpu variables that correspond to their offsets
 682  * within the percpu area. Since the values of all of the symbols need
 683  * to be offsets from the start of the per_cpu area the virtual address
 684  * (sh_addr) of .data..percpu is 0 in SMP kernels.
 685  *
 686  * This means that:
 687  *
 688  *      Relocations that reference symbols in the per_cpu area do not
 689  *      need further relocation (since the value is an offset relative
 690  *      to the start of the per_cpu area that does not change).
 691  *
 692  *      Relocations that apply to the per_cpu area need to have their
 693  *      offset adjusted by by the value of __per_cpu_load to make them
 694  *      point to the correct place in the loaded image (because the
 695  *      virtual address of .data..percpu is 0).
 696  *
 697  * For non SMP kernels .data..percpu is linked as part of the normal
 698  * kernel data and does not require special treatment.
 699  *
 700  */
 701 static int per_cpu_shndx        = -1;
 702 static Elf_Addr per_cpu_load_addr;
 703
 704 static void percpu_init(void)
 705 {
 706         int i;
 707         for (i = 0; i < ehdr.e_shnum; i++) {
 708                 ElfW(Sym) *sym;
 709                 if (strcmp(sec_name(i), ".data..percpu"))
 710                         continue;
 711
 712                 if (secs[i].shdr.sh_addr != 0)  /* non SMP kernel */
 713                         return;
 714
 715                 sym = sym_lookup("__per_cpu_load");
 716                 if (!sym)
 717                         die("can't find __per_cpu_load\n");
 718
 719                 per_cpu_shndx = i;
 720                 per_cpu_load_addr = sym->st_value;
 721                 return;
 722         }
 723 }
 724
 725 #if ELF_BITS == 64
 726
 727 /*
 728  * Check to see if a symbol lies in the .data..percpu section.
 729  *
 730  * The linker incorrectly associates some symbols with the
 731  * .data..percpu section so we also need to check the symbol
 732  * name to make sure that we classify the symbol correctly.
 733  *
 734  * The GNU linker incorrectly associates:
 735  *      __init_begin
 736  *      __per_cpu_load
 737  *
 738  * The "gold" linker incorrectly associates:
 739  *      init_per_cpu__irq_stack_union
 740  *      init_per_cpu__gdt_page
 741  */
 742 static int is_percpu_sym(ElfW(Sym) *sym, const char *symname)
 743 {
 744         return (sym->st_shndx == per_cpu_shndx) &&
 745                 strcmp(symname, "__init_begin") &&
 746                 strcmp(symname, "__per_cpu_load") &&
 747                 strncmp(symname, "init_per_cpu_", 13);
 748 }
 749
 750
 751 static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
 752                       const char *symname)
 753 {
 754         unsigned r_type = ELF64_R_TYPE(rel->r_info);
 755         ElfW(Addr) offset = rel->r_offset;
 756         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 757
 758         if (sym->st_shndx == SHN_UNDEF)
 759                 return 0;
 760
 761         /*
 762          * Adjust the offset if this reloc applies to the percpu section.
 763          */
 764         if (sec->shdr.sh_info == per_cpu_shndx)
 765                 offset += per_cpu_load_addr;
 766
 767         switch (r_type) {
 768         case R_X86_64_NONE:
 769                 /* NONE can be ignored. */
 770                 break;
 771
 772         case R_X86_64_PC32:
 773                 /*
 774                  * PC relative relocations don't need to be adjusted unless
 775                  * referencing a percpu symbol.
 776                  */
 777                 if (is_percpu_sym(sym, symname))
 778                         add_reloc(&relocs32neg, offset);
 779                 break;
 780
 781         case R_X86_64_32:
 782         case R_X86_64_32S:
 783         case R_X86_64_64:
 784                 /*
 785                  * References to the percpu area don't need to be adjusted.
 786                  */
 787                 if (is_percpu_sym(sym, symname))
 788                         break;
 789
 790                 if (shn_abs) {
 791                         /*
 792                          * Whitelisted absolute symbols do not require
 793                          * relocation.
 794                          */
 795                         if (is_reloc(S_ABS, symname))
 796                                 break;
 797
 798                         die("Invalid absolute %s relocation: %s\n",
 799                             rel_type(r_type), symname);
 800                         break;
 801                 }
 802
 803                 /*
 804                  * Relocation offsets for 64 bit kernels are output
 805                  * as 32 bits and sign extended back to 64 bits when
 806                  * the relocations are processed.
 807                  * Make sure that the offset will fit.
 808                  */
 809                 if ((int32_t)offset != (int64_t)offset)
 810                         die("Relocation offset doesn't fit in 32 bits\n");
 811
 812                 if (r_type == R_X86_64_64)
 813                         add_reloc(&relocs64, offset);
 814                 else
 815                         add_reloc(&relocs32, offset);
 816                 break;
 817
 818         default:
 819                 die("Unsupported relocation type: %s (%d)\n",
 820                     rel_type(r_type), r_type);
 821                 break;
 822         }
 823
 824         return 0;
 825 }
 826
 827 #else
 828
 829 static int do_reloc32(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 830                       const char *symname)
 831 {
 832         unsigned r_type = ELF32_R_TYPE(rel->r_info);
 833         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 834
 835         switch (r_type) {
 836         case R_386_NONE:
 837         case R_386_PC32:
 838         case R_386_PC16:
 839         case R_386_PC8:
 840                 /*
 841                  * NONE can be ignored and PC relative relocations don't
 842                  * need to be adjusted.
 843                  */
 844                 break;
 845
 846         case R_386_32:
 847                 if (shn_abs) {
 848                         /*
 849                          * Whitelisted absolute symbols do not require
 850                          * relocation.
 851                          */
 852                         if (is_reloc(S_ABS, symname))
 853                                 break;
 854
 855                         die("Invalid absolute %s relocation: %s\n",
 856                             rel_type(r_type), symname);
 857                         break;
 858                 }
 859
 860                 add_reloc(&relocs32, rel->r_offset);
 861                 break;
 862
 863         default:
 864                 die("Unsupported relocation type: %s (%d)\n",
 865                     rel_type(r_type), r_type);
 866                 break;
 867         }
 868
 869         return 0;
 870 }
 871
 872 static int do_reloc_real(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 873                          const char *symname)
 874 {
 875         unsigned r_type = ELF32_R_TYPE(rel->r_info);
 876         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 877
 878         switch (r_type) {
 879         case R_386_NONE:
 880         case R_386_PC32:
 881         case R_386_PC16:
 882         case R_386_PC8:
 883                 /*
 884                  * NONE can be ignored and PC relative relocations don't
 885                  * need to be adjusted.
 886                  */
 887                 break;
 888
 889         case R_386_16:
 890                 if (shn_abs) {
 891                         /*
 892                          * Whitelisted absolute symbols do not require
 893                          * relocation.
 894                          */
 895                         if (is_reloc(S_ABS, symname))
 896                                 break;
 897
 898                         if (is_reloc(S_SEG, symname)) {
 899                                 add_reloc(&relocs16, rel->r_offset);
 900                                 break;
 901                         }
 902                 } else {
 903                         if (!is_reloc(S_LIN, symname))
 904                                 break;
 905                 }
 906                 die("Invalid %s %s relocation: %s\n",
 907                     shn_abs ? "absolute" : "relative",
 908                     rel_type(r_type), symname);
 909                 break;
 910
 911         case R_386_32:
 912                 if (shn_abs) {
 913                         /*
 914                          * Whitelisted absolute symbols do not require
 915                          * relocation.
 916                          */
 917                         if (is_reloc(S_ABS, symname))
 918                                 break;
 919
 920                         if (is_reloc(S_REL, symname)) {
 921                                 add_reloc(&relocs32, rel->r_offset);
 922                                 break;
 923                         }
 924                 } else {
 925                         if (is_reloc(S_LIN, symname))
 926                                 add_reloc(&relocs32, rel->r_offset);
 927                         break;
 928                 }
 929                 die("Invalid %s %s relocation: %s\n",
 930                     shn_abs ? "absolute" : "relative",
 931                     rel_type(r_type), symname);
 932                 break;
 933
 934         default:
 935                 die("Unsupported relocation type: %s (%d)\n",
 936                     rel_type(r_type), r_type);
 937                 break;
 938         }
 939
 940         return 0;
 941 }
 942
 943 #endif
 944
 945 static int cmp_relocs(const void *va, const void *vb)
 946 {
 947         const uint32_t *a, *b;
 948         a = va; b = vb;
 949         return (*a == *b)? 0 : (*a > *b)? 1 : -1;
 950 }
 951
 952 static void sort_relocs(struct relocs *r)
 953 {
 954         qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
 955 }
 956
 957 static int write32(uint32_t v, FILE *f)
 958 {
 959         unsigned char buf[4];
 960
 961         put_unaligned_le32(v, buf);
 962         return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
 963 }
 964
 965 static int write32_as_text(uint32_t v, FILE *f)
 966 {
 967         return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
 968 }
 969
 970 static void emit_relocs(int as_text, int use_real_mode)
 971 {
 972         int i;
 973         int (*write_reloc)(uint32_t, FILE *) = write32;
 974         int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 975                         const char *symname);
 976
 977 #if ELF_BITS == 64
 978         if (!use_real_mode)
 979                 do_reloc = do_reloc64;
 980         else
 981                 die("--realmode not valid for a 64-bit ELF file");
 982 #else
 983         if (!use_real_mode)
 984                 do_reloc = do_reloc32;
 985         else
 986                 do_reloc = do_reloc_real;
 987 #endif
 988
 989         /* Collect up the relocations */
 990         walk_relocs(do_reloc);
 991
 992         if (relocs16.count && !use_real_mode)
 993                 die("Segment relocations found but --realmode not specified\n");
 994
 995         /* Order the relocations for more efficient processing */
 996         sort_relocs(&relocs32);
 997 #if ELF_BITS == 64
 998         sort_relocs(&relocs32neg);
 999         sort_relocs(&relocs64);
1000 #else
1001         sort_relocs(&relocs16);
1002 #endif
1003
1004         /* Print the relocations */
1005         if (as_text) {
1006                 /* Print the relocations in a form suitable that
1007                  * gas will like.
1008                  */
1009                 printf(".section \".data.reloc\",\"a\"\n");
1010                 printf(".balign 4\n");
1011                 write_reloc = write32_as_text;
1012         }
1013
1014         if (use_real_mode) {
1015                 write_reloc(relocs16.count, stdout);
1016                 for (i = 0; i < relocs16.count; i++)
1017                         write_reloc(relocs16.offset[i], stdout);
1018
1019                 write_reloc(relocs32.count, stdout);
1020                 for (i = 0; i < relocs32.count; i++)
1021                         write_reloc(relocs32.offset[i], stdout);
1022         } else {
1023 #if ELF_BITS == 64
1024                 /* Print a stop */
1025                 write_reloc(0, stdout);
1026
1027                 /* Now print each relocation */
1028                 for (i = 0; i < relocs64.count; i++)
1029                         write_reloc(relocs64.offset[i], stdout);
1030
1031                 /* Print a stop */
1032                 write_reloc(0, stdout);
1033
1034                 /* Now print each inverse 32-bit relocation */
1035                 for (i = 0; i < relocs32neg.count; i++)
1036                         write_reloc(relocs32neg.offset[i], stdout);
1037 #endif
1038
1039                 /* Print a stop */
1040                 write_reloc(0, stdout);
1041
1042                 /* Now print each relocation */
1043                 for (i = 0; i < relocs32.count; i++)
1044                         write_reloc(relocs32.offset[i], stdout);
1045         }
1046 }
1047
1048 /*
1049  * As an aid to debugging problems with different linkers
1050  * print summary information about the relocs.
1051  * Since different linkers tend to emit the sections in
1052  * different orders we use the section names in the output.
1053  */
1054 static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
1055                                 const char *symname)
1056 {
1057         printf("%s\t%s\t%s\t%s\n",
1058                 sec_name(sec->shdr.sh_info),
1059                 rel_type(ELF_R_TYPE(rel->r_info)),
1060                 symname,
1061                 sec_name(sym->st_shndx));
1062         return 0;
1063 }
1064
1065 static void print_reloc_info(void)
1066 {
1067         printf("reloc section\treloc type\tsymbol\tsymbol section\n");
1068         walk_relocs(do_reloc_info);
1069 }
1070
1071 #if ELF_BITS == 64
1072 # define process process_64
1073 #else
1074 # define process process_32
1075 #endif
1076
1077 void process(FILE *fp, int use_real_mode, int as_text,
1078              int show_absolute_syms, int show_absolute_relocs,
1079              int show_reloc_info)
1080 {
1081         regex_init(use_real_mode);
1082         read_ehdr(fp);
1083         read_shdrs(fp);
1084         read_strtabs(fp);
1085         read_symtabs(fp);
1086         read_relocs(fp);
1087         if (ELF_BITS == 64)
1088                 percpu_init();
1089         if (show_absolute_syms) {
1090                 print_absolute_symbols();
1091                 return;
1092         }
1093         if (show_absolute_relocs) {
1094                 print_absolute_relocs();
1095                 return;
1096         }
1097         if (show_reloc_info) {
1098                 print_reloc_info();
1099                 return;
1100         }
1101         emit_relocs(as_text, use_real_mode);
1102 }