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         "__end_rodata_aligned|"
  71         "__initramfs_start|"
  72         "(jiffies|jiffies_64)|"
  73 #if ELF_BITS == 64
  74         "__per_cpu_load|"
  75         "init_per_cpu__.*|"
  76         "__end_rodata_hpage_align|"
  77 #endif
  78         "__vvar_page|"
  79         "_end)$"
  80 };
  81
  82
  83 static const char * const sym_regex_realmode[S_NSYMTYPES] = {
  84 /*
  85  * These symbols are known to be relative, even if the linker marks them
  86  * as absolute (typically defined outside any section in the linker script.)
  87  */
  88         [S_REL] =
  89         "^pa_",
  90
  91 /*
  92  * These are 16-bit segment symbols when compiling 16-bit code.
  93  */
  94         [S_SEG] =
  95         "^real_mode_seg$",
  96
  97 /*
  98  * These are offsets belonging to segments, as opposed to linear addresses,
  99  * when compiling 16-bit code.
 100  */
 101         [S_LIN] =
 102         "^pa_",
 103 };
 104
 105 static const char * const *sym_regex;
 106
 107 static regex_t sym_regex_c[S_NSYMTYPES];
 108 static int is_reloc(enum symtype type, const char *sym_name)
 109 {
 110         return sym_regex[type] &&
 111                 !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
 112 }
 113
 114 static void regex_init(int use_real_mode)
 115 {
 116         char errbuf[128];
 117         int err;
 118         int i;
 119
 120         if (use_real_mode)
 121                 sym_regex = sym_regex_realmode;
 122         else
 123                 sym_regex = sym_regex_kernel;
 124
 125         for (i = 0; i < S_NSYMTYPES; i++) {
 126                 if (!sym_regex[i])
 127                         continue;
 128
 129                 err = regcomp(&sym_regex_c[i], sym_regex[i],
 130                               REG_EXTENDED|REG_NOSUB);
 131
 132                 if (err) {
 133                         regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
 134                         die("%s", errbuf);
 135                 }
 136         }
 137 }
 138
 139 static const char *sym_type(unsigned type)
 140 {
 141         static const char *type_name[] = {
 142 #define SYM_TYPE(X) [X] = #X
 143                 SYM_TYPE(STT_NOTYPE),
 144                 SYM_TYPE(STT_OBJECT),
 145                 SYM_TYPE(STT_FUNC),
 146                 SYM_TYPE(STT_SECTION),
 147                 SYM_TYPE(STT_FILE),
 148                 SYM_TYPE(STT_COMMON),
 149                 SYM_TYPE(STT_TLS),
 150 #undef SYM_TYPE
 151         };
 152         const char *name = "unknown sym type name";
 153         if (type < ARRAY_SIZE(type_name)) {
 154                 name = type_name[type];
 155         }
 156         return name;
 157 }
 158
 159 static const char *sym_bind(unsigned bind)
 160 {
 161         static const char *bind_name[] = {
 162 #define SYM_BIND(X) [X] = #X
 163                 SYM_BIND(STB_LOCAL),
 164                 SYM_BIND(STB_GLOBAL),
 165                 SYM_BIND(STB_WEAK),
 166 #undef SYM_BIND
 167         };
 168         const char *name = "unknown sym bind name";
 169         if (bind < ARRAY_SIZE(bind_name)) {
 170                 name = bind_name[bind];
 171         }
 172         return name;
 173 }
 174
 175 static const char *sym_visibility(unsigned visibility)
 176 {
 177         static const char *visibility_name[] = {
 178 #define SYM_VISIBILITY(X) [X] = #X
 179                 SYM_VISIBILITY(STV_DEFAULT),
 180                 SYM_VISIBILITY(STV_INTERNAL),
 181                 SYM_VISIBILITY(STV_HIDDEN),
 182                 SYM_VISIBILITY(STV_PROTECTED),
 183 #undef SYM_VISIBILITY
 184         };
 185         const char *name = "unknown sym visibility name";
 186         if (visibility < ARRAY_SIZE(visibility_name)) {
 187                 name = visibility_name[visibility];
 188         }
 189         return name;
 190 }
 191
 192 static const char *rel_type(unsigned type)
 193 {
 194         static const char *type_name[] = {
 195 #define REL_TYPE(X) [X] = #X
 196 #if ELF_BITS == 64
 197                 REL_TYPE(R_X86_64_NONE),
 198                 REL_TYPE(R_X86_64_64),
 199                 REL_TYPE(R_X86_64_PC64),
 200                 REL_TYPE(R_X86_64_PC32),
 201                 REL_TYPE(R_X86_64_GOT32),
 202                 REL_TYPE(R_X86_64_PLT32),
 203                 REL_TYPE(R_X86_64_COPY),
 204                 REL_TYPE(R_X86_64_GLOB_DAT),
 205                 REL_TYPE(R_X86_64_JUMP_SLOT),
 206                 REL_TYPE(R_X86_64_RELATIVE),
 207                 REL_TYPE(R_X86_64_GOTPCREL),
 208                 REL_TYPE(R_X86_64_32),
 209                 REL_TYPE(R_X86_64_32S),
 210                 REL_TYPE(R_X86_64_16),
 211                 REL_TYPE(R_X86_64_PC16),
 212                 REL_TYPE(R_X86_64_8),
 213                 REL_TYPE(R_X86_64_PC8),
 214 #else
 215                 REL_TYPE(R_386_NONE),
 216                 REL_TYPE(R_386_32),
 217                 REL_TYPE(R_386_PC32),
 218                 REL_TYPE(R_386_GOT32),
 219                 REL_TYPE(R_386_PLT32),
 220                 REL_TYPE(R_386_COPY),
 221                 REL_TYPE(R_386_GLOB_DAT),
 222                 REL_TYPE(R_386_JMP_SLOT),
 223                 REL_TYPE(R_386_RELATIVE),
 224                 REL_TYPE(R_386_GOTOFF),
 225                 REL_TYPE(R_386_GOTPC),
 226                 REL_TYPE(R_386_8),
 227                 REL_TYPE(R_386_PC8),
 228                 REL_TYPE(R_386_16),
 229                 REL_TYPE(R_386_PC16),
 230 #endif
 231 #undef REL_TYPE
 232         };
 233         const char *name = "unknown type rel type name";
 234         if (type < ARRAY_SIZE(type_name) && type_name[type]) {
 235                 name = type_name[type];
 236         }
 237         return name;
 238 }
 239
 240 static const char *sec_name(unsigned shndx)
 241 {
 242         const char *sec_strtab;
 243         const char *name;
 244         sec_strtab = secs[ehdr.e_shstrndx].strtab;
 245         name = "<noname>";
 246         if (shndx < ehdr.e_shnum) {
 247                 name = sec_strtab + secs[shndx].shdr.sh_name;
 248         }
 249         else if (shndx == SHN_ABS) {
 250                 name = "ABSOLUTE";
 251         }
 252         else if (shndx == SHN_COMMON) {
 253                 name = "COMMON";
 254         }
 255         return name;
 256 }
 257
 258 static const char *sym_name(const char *sym_strtab, Elf_Sym *sym)
 259 {
 260         const char *name;
 261         name = "<noname>";
 262         if (sym->st_name) {
 263                 name = sym_strtab + sym->st_name;
 264         }
 265         else {
 266                 name = sec_name(sym->st_shndx);
 267         }
 268         return name;
 269 }
 270
 271 static Elf_Sym *sym_lookup(const char *symname)
 272 {
 273         int i;
 274         for (i = 0; i < ehdr.e_shnum; i++) {
 275                 struct section *sec = &secs[i];
 276                 long nsyms;
 277                 char *strtab;
 278                 Elf_Sym *symtab;
 279                 Elf_Sym *sym;
 280
 281                 if (sec->shdr.sh_type != SHT_SYMTAB)
 282                         continue;
 283
 284                 nsyms = sec->shdr.sh_size/sizeof(Elf_Sym);
 285                 symtab = sec->symtab;
 286                 strtab = sec->link->strtab;
 287
 288                 for (sym = symtab; --nsyms >= 0; sym++) {
 289                         if (!sym->st_name)
 290                                 continue;
 291                         if (strcmp(symname, strtab + sym->st_name) == 0)
 292                                 return sym;
 293                 }
 294         }
 295         return 0;
 296 }
 297
 298 #if BYTE_ORDER == LITTLE_ENDIAN
 299 #define le16_to_cpu(val) (val)
 300 #define le32_to_cpu(val) (val)
 301 #define le64_to_cpu(val) (val)
 302 #endif
 303 #if BYTE_ORDER == BIG_ENDIAN
 304 #define le16_to_cpu(val) bswap_16(val)
 305 #define le32_to_cpu(val) bswap_32(val)
 306 #define le64_to_cpu(val) bswap_64(val)
 307 #endif
 308
 309 static uint16_t elf16_to_cpu(uint16_t val)
 310 {
 311         return le16_to_cpu(val);
 312 }
 313
 314 static uint32_t elf32_to_cpu(uint32_t val)
 315 {
 316         return le32_to_cpu(val);
 317 }
 318
 319 #define elf_half_to_cpu(x)      elf16_to_cpu(x)
 320 #define elf_word_to_cpu(x)      elf32_to_cpu(x)
 321
 322 #if ELF_BITS == 64
 323 static uint64_t elf64_to_cpu(uint64_t val)
 324 {
 325         return le64_to_cpu(val);
 326 }
 327 #define elf_addr_to_cpu(x)      elf64_to_cpu(x)
 328 #define elf_off_to_cpu(x)       elf64_to_cpu(x)
 329 #define elf_xword_to_cpu(x)     elf64_to_cpu(x)
 330 #else
 331 #define elf_addr_to_cpu(x)      elf32_to_cpu(x)
 332 #define elf_off_to_cpu(x)       elf32_to_cpu(x)
 333 #define elf_xword_to_cpu(x)     elf32_to_cpu(x)
 334 #endif
 335
 336 static void read_ehdr(FILE *fp)
 337 {
 338         if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
 339                 die("Cannot read ELF header: %s\n",
 340                         strerror(errno));
 341         }
 342         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
 343                 die("No ELF magic\n");
 344         }
 345         if (ehdr.e_ident[EI_CLASS] != ELF_CLASS) {
 346                 die("Not a %d bit executable\n", ELF_BITS);
 347         }
 348         if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
 349                 die("Not a LSB ELF executable\n");
 350         }
 351         if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
 352                 die("Unknown ELF version\n");
 353         }
 354         /* Convert the fields to native endian */
 355         ehdr.e_type      = elf_half_to_cpu(ehdr.e_type);
 356         ehdr.e_machine   = elf_half_to_cpu(ehdr.e_machine);
 357         ehdr.e_version   = elf_word_to_cpu(ehdr.e_version);
 358         ehdr.e_entry     = elf_addr_to_cpu(ehdr.e_entry);
 359         ehdr.e_phoff     = elf_off_to_cpu(ehdr.e_phoff);
 360         ehdr.e_shoff     = elf_off_to_cpu(ehdr.e_shoff);
 361         ehdr.e_flags     = elf_word_to_cpu(ehdr.e_flags);
 362         ehdr.e_ehsize    = elf_half_to_cpu(ehdr.e_ehsize);
 363         ehdr.e_phentsize = elf_half_to_cpu(ehdr.e_phentsize);
 364         ehdr.e_phnum     = elf_half_to_cpu(ehdr.e_phnum);
 365         ehdr.e_shentsize = elf_half_to_cpu(ehdr.e_shentsize);
 366         ehdr.e_shnum     = elf_half_to_cpu(ehdr.e_shnum);
 367         ehdr.e_shstrndx  = elf_half_to_cpu(ehdr.e_shstrndx);
 368
 369         if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
 370                 die("Unsupported ELF header type\n");
 371         }
 372         if (ehdr.e_machine != ELF_MACHINE) {
 373                 die("Not for %s\n", ELF_MACHINE_NAME);
 374         }
 375         if (ehdr.e_version != EV_CURRENT) {
 376                 die("Unknown ELF version\n");
 377         }
 378         if (ehdr.e_ehsize != sizeof(Elf_Ehdr)) {
 379                 die("Bad Elf header size\n");
 380         }
 381         if (ehdr.e_phentsize != sizeof(Elf_Phdr)) {
 382                 die("Bad program header entry\n");
 383         }
 384         if (ehdr.e_shentsize != sizeof(Elf_Shdr)) {
 385                 die("Bad section header entry\n");
 386         }
 387         if (ehdr.e_shstrndx >= ehdr.e_shnum) {
 388                 die("String table index out of bounds\n");
 389         }
 390 }
 391
 392 static void read_shdrs(FILE *fp)
 393 {
 394         int i;
 395         Elf_Shdr shdr;
 396
 397         secs = calloc(ehdr.e_shnum, sizeof(struct section));
 398         if (!secs) {
 399                 die("Unable to allocate %d section headers\n",
 400                     ehdr.e_shnum);
 401         }
 402         if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
 403                 die("Seek to %d failed: %s\n",
 404                         ehdr.e_shoff, strerror(errno));
 405         }
 406         for (i = 0; i < ehdr.e_shnum; i++) {
 407                 struct section *sec = &secs[i];
 408                 if (fread(&shdr, sizeof shdr, 1, fp) != 1)
 409                         die("Cannot read ELF section headers %d/%d: %s\n",
 410                             i, ehdr.e_shnum, strerror(errno));
 411                 sec->shdr.sh_name      = elf_word_to_cpu(shdr.sh_name);
 412                 sec->shdr.sh_type      = elf_word_to_cpu(shdr.sh_type);
 413                 sec->shdr.sh_flags     = elf_xword_to_cpu(shdr.sh_flags);
 414                 sec->shdr.sh_addr      = elf_addr_to_cpu(shdr.sh_addr);
 415                 sec->shdr.sh_offset    = elf_off_to_cpu(shdr.sh_offset);
 416                 sec->shdr.sh_size      = elf_xword_to_cpu(shdr.sh_size);
 417                 sec->shdr.sh_link      = elf_word_to_cpu(shdr.sh_link);
 418                 sec->shdr.sh_info      = elf_word_to_cpu(shdr.sh_info);
 419                 sec->shdr.sh_addralign = elf_xword_to_cpu(shdr.sh_addralign);
 420                 sec->shdr.sh_entsize   = elf_xword_to_cpu(shdr.sh_entsize);
 421                 if (sec->shdr.sh_link < ehdr.e_shnum)
 422                         sec->link = &secs[sec->shdr.sh_link];
 423         }
 424
 425 }
 426
 427 static void read_strtabs(FILE *fp)
 428 {
 429         int i;
 430         for (i = 0; i < ehdr.e_shnum; i++) {
 431                 struct section *sec = &secs[i];
 432                 if (sec->shdr.sh_type != SHT_STRTAB) {
 433                         continue;
 434                 }
 435                 sec->strtab = malloc(sec->shdr.sh_size);
 436                 if (!sec->strtab) {
 437                         die("malloc of %d bytes for strtab failed\n",
 438                                 sec->shdr.sh_size);
 439                 }
 440                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 441                         die("Seek to %d failed: %s\n",
 442                                 sec->shdr.sh_offset, strerror(errno));
 443                 }
 444                 if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
 445                     != sec->shdr.sh_size) {
 446                         die("Cannot read symbol table: %s\n",
 447                                 strerror(errno));
 448                 }
 449         }
 450 }
 451
 452 static void read_symtabs(FILE *fp)
 453 {
 454         int i,j;
 455         for (i = 0; i < ehdr.e_shnum; i++) {
 456                 struct section *sec = &secs[i];
 457                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 458                         continue;
 459                 }
 460                 sec->symtab = malloc(sec->shdr.sh_size);
 461                 if (!sec->symtab) {
 462                         die("malloc of %d bytes for symtab failed\n",
 463                                 sec->shdr.sh_size);
 464                 }
 465                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 466                         die("Seek to %d failed: %s\n",
 467                                 sec->shdr.sh_offset, strerror(errno));
 468                 }
 469                 if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
 470                     != sec->shdr.sh_size) {
 471                         die("Cannot read symbol table: %s\n",
 472                                 strerror(errno));
 473                 }
 474                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
 475                         Elf_Sym *sym = &sec->symtab[j];
 476                         sym->st_name  = elf_word_to_cpu(sym->st_name);
 477                         sym->st_value = elf_addr_to_cpu(sym->st_value);
 478                         sym->st_size  = elf_xword_to_cpu(sym->st_size);
 479                         sym->st_shndx = elf_half_to_cpu(sym->st_shndx);
 480                 }
 481         }
 482 }
 483
 484
 485 static void read_relocs(FILE *fp)
 486 {
 487         int i,j;
 488         for (i = 0; i < ehdr.e_shnum; i++) {
 489                 struct section *sec = &secs[i];
 490                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 491                         continue;
 492                 }
 493                 sec->reltab = malloc(sec->shdr.sh_size);
 494                 if (!sec->reltab) {
 495                         die("malloc of %d bytes for relocs failed\n",
 496                                 sec->shdr.sh_size);
 497                 }
 498                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 499                         die("Seek to %d failed: %s\n",
 500                                 sec->shdr.sh_offset, strerror(errno));
 501                 }
 502                 if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
 503                     != sec->shdr.sh_size) {
 504                         die("Cannot read symbol table: %s\n",
 505                                 strerror(errno));
 506                 }
 507                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 508                         Elf_Rel *rel = &sec->reltab[j];
 509                         rel->r_offset = elf_addr_to_cpu(rel->r_offset);
 510                         rel->r_info   = elf_xword_to_cpu(rel->r_info);
 511 #if (SHT_REL_TYPE == SHT_RELA)
 512                         rel->r_addend = elf_xword_to_cpu(rel->r_addend);
 513 #endif
 514                 }
 515         }
 516 }
 517
 518
 519 static void print_absolute_symbols(void)
 520 {
 521         int i;
 522         const char *format;
 523
 524         if (ELF_BITS == 64)
 525                 format = "%5d %016"PRIx64" %5"PRId64" %10s %10s %12s %s\n";
 526         else
 527                 format = "%5d %08"PRIx32"  %5"PRId32" %10s %10s %12s %s\n";
 528
 529         printf("Absolute symbols\n");
 530         printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
 531         for (i = 0; i < ehdr.e_shnum; i++) {
 532                 struct section *sec = &secs[i];
 533                 char *sym_strtab;
 534                 int j;
 535
 536                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 537                         continue;
 538                 }
 539                 sym_strtab = sec->link->strtab;
 540                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
 541                         Elf_Sym *sym;
 542                         const char *name;
 543                         sym = &sec->symtab[j];
 544                         name = sym_name(sym_strtab, sym);
 545                         if (sym->st_shndx != SHN_ABS) {
 546                                 continue;
 547                         }
 548                         printf(format,
 549                                 j, sym->st_value, sym->st_size,
 550                                 sym_type(ELF_ST_TYPE(sym->st_info)),
 551                                 sym_bind(ELF_ST_BIND(sym->st_info)),
 552                                 sym_visibility(ELF_ST_VISIBILITY(sym->st_other)),
 553                                 name);
 554                 }
 555         }
 556         printf("\n");
 557 }
 558
 559 static void print_absolute_relocs(void)
 560 {
 561         int i, printed = 0;
 562         const char *format;
 563
 564         if (ELF_BITS == 64)
 565                 format = "%016"PRIx64" %016"PRIx64" %10s %016"PRIx64"  %s\n";
 566         else
 567                 format = "%08"PRIx32" %08"PRIx32" %10s %08"PRIx32"  %s\n";
 568
 569         for (i = 0; i < ehdr.e_shnum; i++) {
 570                 struct section *sec = &secs[i];
 571                 struct section *sec_applies, *sec_symtab;
 572                 char *sym_strtab;
 573                 Elf_Sym *sh_symtab;
 574                 int j;
 575                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 576                         continue;
 577                 }
 578                 sec_symtab  = sec->link;
 579                 sec_applies = &secs[sec->shdr.sh_info];
 580                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 581                         continue;
 582                 }
 583                 sh_symtab  = sec_symtab->symtab;
 584                 sym_strtab = sec_symtab->link->strtab;
 585                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 586                         Elf_Rel *rel;
 587                         Elf_Sym *sym;
 588                         const char *name;
 589                         rel = &sec->reltab[j];
 590                         sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
 591                         name = sym_name(sym_strtab, sym);
 592                         if (sym->st_shndx != SHN_ABS) {
 593                                 continue;
 594                         }
 595
 596                         /* Absolute symbols are not relocated if bzImage is
 597                          * loaded at a non-compiled address. Display a warning
 598                          * to user at compile time about the absolute
 599                          * relocations present.
 600                          *
 601                          * User need to audit the code to make sure
 602                          * some symbols which should have been section
 603                          * relative have not become absolute because of some
 604                          * linker optimization or wrong programming usage.
 605                          *
 606                          * Before warning check if this absolute symbol
 607                          * relocation is harmless.
 608                          */
 609                         if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
 610                                 continue;
 611
 612                         if (!printed) {
 613                                 printf("WARNING: Absolute relocations"
 614                                         " present\n");
 615                                 printf("Offset     Info     Type     Sym.Value "
 616                                         "Sym.Name\n");
 617                                 printed = 1;
 618                         }
 619
 620                         printf(format,
 621                                 rel->r_offset,
 622                                 rel->r_info,
 623                                 rel_type(ELF_R_TYPE(rel->r_info)),
 624                                 sym->st_value,
 625                                 name);
 626                 }
 627         }
 628
 629         if (printed)
 630                 printf("\n");
 631 }
 632
 633 static void add_reloc(struct relocs *r, uint32_t offset)
 634 {
 635         if (r->count == r->size) {
 636                 unsigned long newsize = r->size + 50000;
 637                 void *mem = realloc(r->offset, newsize * sizeof(r->offset[0]));
 638
 639                 if (!mem)
 640                         die("realloc of %ld entries for relocs failed\n",
 641                                 newsize);
 642                 r->offset = mem;
 643                 r->size = newsize;
 644         }
 645         r->offset[r->count++] = offset;
 646 }
 647
 648 static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
 649                         Elf_Sym *sym, const char *symname))
 650 {
 651         int i;
 652         /* Walk through the relocations */
 653         for (i = 0; i < ehdr.e_shnum; i++) {
 654                 char *sym_strtab;
 655                 Elf_Sym *sh_symtab;
 656                 struct section *sec_applies, *sec_symtab;
 657                 int j;
 658                 struct section *sec = &secs[i];
 659
 660                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 661                         continue;
 662                 }
 663                 sec_symtab  = sec->link;
 664                 sec_applies = &secs[sec->shdr.sh_info];
 665                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 666                         continue;
 667                 }
 668                 sh_symtab = sec_symtab->symtab;
 669                 sym_strtab = sec_symtab->link->strtab;
 670                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 671                         Elf_Rel *rel = &sec->reltab[j];
 672                         Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
 673                         const char *symname = sym_name(sym_strtab, sym);
 674
 675                         process(sec, rel, sym, symname);
 676                 }
 677         }
 678 }
 679
 680 /*
 681  * The .data..percpu section is a special case for x86_64 SMP kernels.
 682  * It is used to initialize the actual per_cpu areas and to provide
 683  * definitions for the per_cpu variables that correspond to their offsets
 684  * within the percpu area. Since the values of all of the symbols need
 685  * to be offsets from the start of the per_cpu area the virtual address
 686  * (sh_addr) of .data..percpu is 0 in SMP kernels.
 687  *
 688  * This means that:
 689  *
 690  *      Relocations that reference symbols in the per_cpu area do not
 691  *      need further relocation (since the value is an offset relative
 692  *      to the start of the per_cpu area that does not change).
 693  *
 694  *      Relocations that apply to the per_cpu area need to have their
 695  *      offset adjusted by by the value of __per_cpu_load to make them
 696  *      point to the correct place in the loaded image (because the
 697  *      virtual address of .data..percpu is 0).
 698  *
 699  * For non SMP kernels .data..percpu is linked as part of the normal
 700  * kernel data and does not require special treatment.
 701  *
 702  */
 703 static int per_cpu_shndx        = -1;
 704 static Elf_Addr per_cpu_load_addr;
 705
 706 static void percpu_init(void)
 707 {
 708         int i;
 709         for (i = 0; i < ehdr.e_shnum; i++) {
 710                 ElfW(Sym) *sym;
 711                 if (strcmp(sec_name(i), ".data..percpu"))
 712                         continue;
 713
 714                 if (secs[i].shdr.sh_addr != 0)  /* non SMP kernel */
 715                         return;
 716
 717                 sym = sym_lookup("__per_cpu_load");
 718                 if (!sym)
 719                         die("can't find __per_cpu_load\n");
 720
 721                 per_cpu_shndx = i;
 722                 per_cpu_load_addr = sym->st_value;
 723                 return;
 724         }
 725 }
 726
 727 #if ELF_BITS == 64
 728
 729 /*
 730  * Check to see if a symbol lies in the .data..percpu section.
 731  *
 732  * The linker incorrectly associates some symbols with the
 733  * .data..percpu section so we also need to check the symbol
 734  * name to make sure that we classify the symbol correctly.
 735  *
 736  * The GNU linker incorrectly associates:
 737  *      __init_begin
 738  *      __per_cpu_load
 739  *
 740  * The "gold" linker incorrectly associates:
 741  *      init_per_cpu__irq_stack_union
 742  *      init_per_cpu__gdt_page
 743  */
 744 static int is_percpu_sym(ElfW(Sym) *sym, const char *symname)
 745 {
 746         return (sym->st_shndx == per_cpu_shndx) &&
 747                 strcmp(symname, "__init_begin") &&
 748                 strcmp(symname, "__per_cpu_load") &&
 749                 strncmp(symname, "init_per_cpu_", 13);
 750 }
 751
 752
 753 static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
 754                       const char *symname)
 755 {
 756         unsigned r_type = ELF64_R_TYPE(rel->r_info);
 757         ElfW(Addr) offset = rel->r_offset;
 758         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 759
 760         if (sym->st_shndx == SHN_UNDEF)
 761                 return 0;
 762
 763         /*
 764          * Adjust the offset if this reloc applies to the percpu section.
 765          */
 766         if (sec->shdr.sh_info == per_cpu_shndx)
 767                 offset += per_cpu_load_addr;
 768
 769         switch (r_type) {
 770         case R_X86_64_NONE:
 771                 /* NONE can be ignored. */
 772                 break;
 773
 774         case R_X86_64_PC32:
 775         case R_X86_64_PLT32:
 776                 /*
 777                  * PC relative relocations don't need to be adjusted unless
 778                  * referencing a percpu symbol.
 779                  *
 780                  * NB: R_X86_64_PLT32 can be treated as R_X86_64_PC32.
 781                  */
 782                 if (is_percpu_sym(sym, symname))
 783                         add_reloc(&relocs32neg, offset);
 784                 break;
 785
 786         case R_X86_64_PC64:
 787                 /*
 788                  * Only used by jump labels
 789                  */
 790                 if (is_percpu_sym(sym, symname))
 791                         die("Invalid R_X86_64_PC64 relocation against per-CPU symbol %s\n",
 792                             symname);
 793                 break;
 794
 795         case R_X86_64_32:
 796         case R_X86_64_32S:
 797         case R_X86_64_64:
 798                 /*
 799                  * References to the percpu area don't need to be adjusted.
 800                  */
 801                 if (is_percpu_sym(sym, symname))
 802                         break;
 803
 804                 if (shn_abs) {
 805                         /*
 806                          * Whitelisted absolute symbols do not require
 807                          * relocation.
 808                          */
 809                         if (is_reloc(S_ABS, symname))
 810                                 break;
 811
 812                         die("Invalid absolute %s relocation: %s\n",
 813                             rel_type(r_type), symname);
 814                         break;
 815                 }
 816
 817                 /*
 818                  * Relocation offsets for 64 bit kernels are output
 819                  * as 32 bits and sign extended back to 64 bits when
 820                  * the relocations are processed.
 821                  * Make sure that the offset will fit.
 822                  */
 823                 if ((int32_t)offset != (int64_t)offset)
 824                         die("Relocation offset doesn't fit in 32 bits\n");
 825
 826                 if (r_type == R_X86_64_64)
 827                         add_reloc(&relocs64, offset);
 828                 else
 829                         add_reloc(&relocs32, offset);
 830                 break;
 831
 832         default:
 833                 die("Unsupported relocation type: %s (%d)\n",
 834                     rel_type(r_type), r_type);
 835                 break;
 836         }
 837
 838         return 0;
 839 }
 840
 841 #else
 842
 843 static int do_reloc32(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 844                       const char *symname)
 845 {
 846         unsigned r_type = ELF32_R_TYPE(rel->r_info);
 847         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 848
 849         switch (r_type) {
 850         case R_386_NONE:
 851         case R_386_PC32:
 852         case R_386_PC16:
 853         case R_386_PC8:
 854                 /*
 855                  * NONE can be ignored and PC relative relocations don't
 856                  * need to be adjusted.
 857                  */
 858                 break;
 859
 860         case R_386_32:
 861                 if (shn_abs) {
 862                         /*
 863                          * Whitelisted absolute symbols do not require
 864                          * relocation.
 865                          */
 866                         if (is_reloc(S_ABS, symname))
 867                                 break;
 868
 869                         die("Invalid absolute %s relocation: %s\n",
 870                             rel_type(r_type), symname);
 871                         break;
 872                 }
 873
 874                 add_reloc(&relocs32, rel->r_offset);
 875                 break;
 876
 877         default:
 878                 die("Unsupported relocation type: %s (%d)\n",
 879                     rel_type(r_type), r_type);
 880                 break;
 881         }
 882
 883         return 0;
 884 }
 885
 886 static int do_reloc_real(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 887                          const char *symname)
 888 {
 889         unsigned r_type = ELF32_R_TYPE(rel->r_info);
 890         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 891
 892         switch (r_type) {
 893         case R_386_NONE:
 894         case R_386_PC32:
 895         case R_386_PC16:
 896         case R_386_PC8:
 897                 /*
 898                  * NONE can be ignored and PC relative relocations don't
 899                  * need to be adjusted.
 900                  */
 901                 break;
 902
 903         case R_386_16:
 904                 if (shn_abs) {
 905                         /*
 906                          * Whitelisted absolute symbols do not require
 907                          * relocation.
 908                          */
 909                         if (is_reloc(S_ABS, symname))
 910                                 break;
 911
 912                         if (is_reloc(S_SEG, symname)) {
 913                                 add_reloc(&relocs16, rel->r_offset);
 914                                 break;
 915                         }
 916                 } else {
 917                         if (!is_reloc(S_LIN, symname))
 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         case R_386_32:
 926                 if (shn_abs) {
 927                         /*
 928                          * Whitelisted absolute symbols do not require
 929                          * relocation.
 930                          */
 931                         if (is_reloc(S_ABS, symname))
 932                                 break;
 933
 934                         if (is_reloc(S_REL, symname)) {
 935                                 add_reloc(&relocs32, rel->r_offset);
 936                                 break;
 937                         }
 938                 } else {
 939                         if (is_reloc(S_LIN, symname))
 940                                 add_reloc(&relocs32, rel->r_offset);
 941                         break;
 942                 }
 943                 die("Invalid %s %s relocation: %s\n",
 944                     shn_abs ? "absolute" : "relative",
 945                     rel_type(r_type), symname);
 946                 break;
 947
 948         default:
 949                 die("Unsupported relocation type: %s (%d)\n",
 950                     rel_type(r_type), r_type);
 951                 break;
 952         }
 953
 954         return 0;
 955 }
 956
 957 #endif
 958
 959 static int cmp_relocs(const void *va, const void *vb)
 960 {
 961         const uint32_t *a, *b;
 962         a = va; b = vb;
 963         return (*a == *b)? 0 : (*a > *b)? 1 : -1;
 964 }
 965
 966 static void sort_relocs(struct relocs *r)
 967 {
 968         qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
 969 }
 970
 971 static int write32(uint32_t v, FILE *f)
 972 {
 973         unsigned char buf[4];
 974
 975         put_unaligned_le32(v, buf);
 976         return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
 977 }
 978
 979 static int write32_as_text(uint32_t v, FILE *f)
 980 {
 981         return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
 982 }
 983
 984 static void emit_relocs(int as_text, int use_real_mode)
 985 {
 986         int i;
 987         int (*write_reloc)(uint32_t, FILE *) = write32;
 988         int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 989                         const char *symname);
 990
 991 #if ELF_BITS == 64
 992         if (!use_real_mode)
 993                 do_reloc = do_reloc64;
 994         else
 995                 die("--realmode not valid for a 64-bit ELF file");
 996 #else
 997         if (!use_real_mode)
 998                 do_reloc = do_reloc32;
 999         else
1000                 do_reloc = do_reloc_real;
1001 #endif
1002
1003         /* Collect up the relocations */
1004         walk_relocs(do_reloc);
1005
1006         if (relocs16.count && !use_real_mode)
1007                 die("Segment relocations found but --realmode not specified\n");
1008
1009         /* Order the relocations for more efficient processing */
1010         sort_relocs(&relocs32);
1011 #if ELF_BITS == 64
1012         sort_relocs(&relocs32neg);
1013         sort_relocs(&relocs64);
1014 #else
1015         sort_relocs(&relocs16);
1016 #endif
1017
1018         /* Print the relocations */
1019         if (as_text) {
1020                 /* Print the relocations in a form suitable that
1021                  * gas will like.
1022                  */
1023                 printf(".section \".data.reloc\",\"a\"\n");
1024                 printf(".balign 4\n");
1025                 write_reloc = write32_as_text;
1026         }
1027
1028         if (use_real_mode) {
1029                 write_reloc(relocs16.count, stdout);
1030                 for (i = 0; i < relocs16.count; i++)
1031                         write_reloc(relocs16.offset[i], stdout);
1032
1033                 write_reloc(relocs32.count, stdout);
1034                 for (i = 0; i < relocs32.count; i++)
1035                         write_reloc(relocs32.offset[i], stdout);
1036         } else {
1037 #if ELF_BITS == 64
1038                 /* Print a stop */
1039                 write_reloc(0, stdout);
1040
1041                 /* Now print each relocation */
1042                 for (i = 0; i < relocs64.count; i++)
1043                         write_reloc(relocs64.offset[i], stdout);
1044
1045                 /* Print a stop */
1046                 write_reloc(0, stdout);
1047
1048                 /* Now print each inverse 32-bit relocation */
1049                 for (i = 0; i < relocs32neg.count; i++)
1050                         write_reloc(relocs32neg.offset[i], stdout);
1051 #endif
1052
1053                 /* Print a stop */
1054                 write_reloc(0, stdout);
1055
1056                 /* Now print each relocation */
1057                 for (i = 0; i < relocs32.count; i++)
1058                         write_reloc(relocs32.offset[i], stdout);
1059         }
1060 }
1061
1062 /*
1063  * As an aid to debugging problems with different linkers
1064  * print summary information about the relocs.
1065  * Since different linkers tend to emit the sections in
1066  * different orders we use the section names in the output.
1067  */
1068 static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
1069                                 const char *symname)
1070 {
1071         printf("%s\t%s\t%s\t%s\n",
1072                 sec_name(sec->shdr.sh_info),
1073                 rel_type(ELF_R_TYPE(rel->r_info)),
1074                 symname,
1075                 sec_name(sym->st_shndx));
1076         return 0;
1077 }
1078
1079 static void print_reloc_info(void)
1080 {
1081         printf("reloc section\treloc type\tsymbol\tsymbol section\n");
1082         walk_relocs(do_reloc_info);
1083 }
1084
1085 #if ELF_BITS == 64
1086 # define process process_64
1087 #else
1088 # define process process_32
1089 #endif
1090
1091 void process(FILE *fp, int use_real_mode, int as_text,
1092              int show_absolute_syms, int show_absolute_relocs,
1093              int show_reloc_info)
1094 {
1095         regex_init(use_real_mode);
1096         read_ehdr(fp);
1097         read_shdrs(fp);
1098         read_strtabs(fp);
1099         read_symtabs(fp);
1100         read_relocs(fp);
1101         if (ELF_BITS == 64)
1102                 percpu_init();
1103         if (show_absolute_syms) {
1104                 print_absolute_symbols();
1105                 return;
1106         }
1107         if (show_absolute_relocs) {
1108                 print_absolute_relocs();
1109                 return;
1110         }
1111         if (show_reloc_info) {
1112                 print_reloc_info();
1113                 return;
1114         }
1115         emit_relocs(as_text, use_real_mode);
1116 }