arch/x86/tools/relocs.c

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