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