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 static unsigned long    shnum;
  16 static unsigned int     shstrndx;
  17
  18 struct relocs {
  19         uint32_t        *offset;
  20         unsigned long   count;
  21         unsigned long   size;
  22 };
  23
  24 static struct relocs relocs16;
  25 static struct relocs relocs32;
  26 #if ELF_BITS == 64
  27 static struct relocs relocs32neg;
  28 static struct relocs relocs64;
  29 #endif
  30
  31 struct section {
  32         Elf_Shdr       shdr;
  33         struct section *link;
  34         Elf_Sym        *symtab;
  35         Elf_Rel        *reltab;
  36         char           *strtab;
  37 };
  38 static struct section *secs;
  39
  40 static const char * const sym_regex_kernel[S_NSYMTYPES] = {
  41 /*
  42  * Following symbols have been audited. There values are constant and do
  43  * not change if bzImage is loaded at a different physical address than
  44  * the address for which it has been compiled. Don't warn user about
  45  * absolute relocations present w.r.t these symbols.
  46  */
  47         [S_ABS] =
  48         "^(xen_irq_disable_direct_reloc$|"
  49         "xen_save_fl_direct_reloc$|"
  50         "VDSO|"
  51         "__crc_)",
  52
  53 /*
  54  * These symbols are known to be relative, even if the linker marks them
  55  * as absolute (typically defined outside any section in the linker script.)
  56  */
  57         [S_REL] =
  58         "^(__init_(begin|end)|"
  59         "__x86_cpu_dev_(start|end)|"
  60         "(__parainstructions|__alt_instructions)(|_end)|"
  61         "(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
  62         "__(start|end)_pci_.*|"
  63         "__(start|end)_builtin_fw|"
  64         "__(start|stop)___ksymtab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
  65         "__(start|stop)___kcrctab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
  66         "__(start|stop)___param|"
  67         "__(start|stop)___modver|"
  68         "__(start|stop)___bug_table|"
  69         "__tracedata_(start|end)|"
  70         "__(start|stop)_notes|"
  71         "__end_rodata|"
  72         "__end_rodata_aligned|"
  73         "__initramfs_start|"
  74         "(jiffies|jiffies_64)|"
  75 #if ELF_BITS == 64
  76         "__per_cpu_load|"
  77         "init_per_cpu__.*|"
  78         "__end_rodata_hpage_align|"
  79 #endif
  80         "__vvar_page|"
  81         "_end)$"
  82 };
  83
  84
  85 static const char * const sym_regex_realmode[S_NSYMTYPES] = {
  86 /*
  87  * These symbols are known to be relative, even if the linker marks them
  88  * as absolute (typically defined outside any section in the linker script.)
  89  */
  90         [S_REL] =
  91         "^pa_",
  92
  93 /*
  94  * These are 16-bit segment symbols when compiling 16-bit code.
  95  */
  96         [S_SEG] =
  97         "^real_mode_seg$",
  98
  99 /*
 100  * These are offsets belonging to segments, as opposed to linear addresses,
 101  * when compiling 16-bit code.
 102  */
 103         [S_LIN] =
 104         "^pa_",
 105 };
 106
 107 static const char * const *sym_regex;
 108
 109 static regex_t sym_regex_c[S_NSYMTYPES];
 110 static int is_reloc(enum symtype type, const char *sym_name)
 111 {
 112         return sym_regex[type] &&
 113                 !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
 114 }
 115
 116 static void regex_init(int use_real_mode)
 117 {
 118         char errbuf[128];
 119         int err;
 120         int i;
 121
 122         if (use_real_mode)
 123                 sym_regex = sym_regex_realmode;
 124         else
 125                 sym_regex = sym_regex_kernel;
 126
 127         for (i = 0; i < S_NSYMTYPES; i++) {
 128                 if (!sym_regex[i])
 129                         continue;
 130
 131                 err = regcomp(&sym_regex_c[i], sym_regex[i],
 132                               REG_EXTENDED|REG_NOSUB);
 133
 134                 if (err) {
 135                         regerror(err, &sym_regex_c[i], errbuf, sizeof(errbuf));
 136                         die("%s", errbuf);
 137                 }
 138         }
 139 }
 140
 141 static const char *sym_type(unsigned type)
 142 {
 143         static const char *type_name[] = {
 144 #define SYM_TYPE(X) [X] = #X
 145                 SYM_TYPE(STT_NOTYPE),
 146                 SYM_TYPE(STT_OBJECT),
 147                 SYM_TYPE(STT_FUNC),
 148                 SYM_TYPE(STT_SECTION),
 149                 SYM_TYPE(STT_FILE),
 150                 SYM_TYPE(STT_COMMON),
 151                 SYM_TYPE(STT_TLS),
 152 #undef SYM_TYPE
 153         };
 154         const char *name = "unknown sym type name";
 155         if (type < ARRAY_SIZE(type_name)) {
 156                 name = type_name[type];
 157         }
 158         return name;
 159 }
 160
 161 static const char *sym_bind(unsigned bind)
 162 {
 163         static const char *bind_name[] = {
 164 #define SYM_BIND(X) [X] = #X
 165                 SYM_BIND(STB_LOCAL),
 166                 SYM_BIND(STB_GLOBAL),
 167                 SYM_BIND(STB_WEAK),
 168 #undef SYM_BIND
 169         };
 170         const char *name = "unknown sym bind name";
 171         if (bind < ARRAY_SIZE(bind_name)) {
 172                 name = bind_name[bind];
 173         }
 174         return name;
 175 }
 176
 177 static const char *sym_visibility(unsigned visibility)
 178 {
 179         static const char *visibility_name[] = {
 180 #define SYM_VISIBILITY(X) [X] = #X
 181                 SYM_VISIBILITY(STV_DEFAULT),
 182                 SYM_VISIBILITY(STV_INTERNAL),
 183                 SYM_VISIBILITY(STV_HIDDEN),
 184                 SYM_VISIBILITY(STV_PROTECTED),
 185 #undef SYM_VISIBILITY
 186         };
 187         const char *name = "unknown sym visibility name";
 188         if (visibility < ARRAY_SIZE(visibility_name)) {
 189                 name = visibility_name[visibility];
 190         }
 191         return name;
 192 }
 193
 194 static const char *rel_type(unsigned type)
 195 {
 196         static const char *type_name[] = {
 197 #define REL_TYPE(X) [X] = #X
 198 #if ELF_BITS == 64
 199                 REL_TYPE(R_X86_64_NONE),
 200                 REL_TYPE(R_X86_64_64),
 201                 REL_TYPE(R_X86_64_PC64),
 202                 REL_TYPE(R_X86_64_PC32),
 203                 REL_TYPE(R_X86_64_GOT32),
 204                 REL_TYPE(R_X86_64_PLT32),
 205                 REL_TYPE(R_X86_64_COPY),
 206                 REL_TYPE(R_X86_64_GLOB_DAT),
 207                 REL_TYPE(R_X86_64_JUMP_SLOT),
 208                 REL_TYPE(R_X86_64_RELATIVE),
 209                 REL_TYPE(R_X86_64_GOTPCREL),
 210                 REL_TYPE(R_X86_64_32),
 211                 REL_TYPE(R_X86_64_32S),
 212                 REL_TYPE(R_X86_64_16),
 213                 REL_TYPE(R_X86_64_PC16),
 214                 REL_TYPE(R_X86_64_8),
 215                 REL_TYPE(R_X86_64_PC8),
 216 #else
 217                 REL_TYPE(R_386_NONE),
 218                 REL_TYPE(R_386_32),
 219                 REL_TYPE(R_386_PC32),
 220                 REL_TYPE(R_386_GOT32),
 221                 REL_TYPE(R_386_PLT32),
 222                 REL_TYPE(R_386_COPY),
 223                 REL_TYPE(R_386_GLOB_DAT),
 224                 REL_TYPE(R_386_JMP_SLOT),
 225                 REL_TYPE(R_386_RELATIVE),
 226                 REL_TYPE(R_386_GOTOFF),
 227                 REL_TYPE(R_386_GOTPC),
 228                 REL_TYPE(R_386_8),
 229                 REL_TYPE(R_386_PC8),
 230                 REL_TYPE(R_386_16),
 231                 REL_TYPE(R_386_PC16),
 232 #endif
 233 #undef REL_TYPE
 234         };
 235         const char *name = "unknown type rel type name";
 236         if (type < ARRAY_SIZE(type_name) && type_name[type]) {
 237                 name = type_name[type];
 238         }
 239         return name;
 240 }
 241
 242 static const char *sec_name(unsigned shndx)
 243 {
 244         const char *sec_strtab;
 245         const char *name;
 246         sec_strtab = secs[shstrndx].strtab;
 247         name = "<noname>";
 248         if (shndx < shnum) {
 249                 name = sec_strtab + secs[shndx].shdr.sh_name;
 250         }
 251         else if (shndx == SHN_ABS) {
 252                 name = "ABSOLUTE";
 253         }
 254         else if (shndx == SHN_COMMON) {
 255                 name = "COMMON";
 256         }
 257         return name;
 258 }
 259
 260 static const char *sym_name(const char *sym_strtab, Elf_Sym *sym)
 261 {
 262         const char *name;
 263         name = "<noname>";
 264         if (sym->st_name) {
 265                 name = sym_strtab + sym->st_name;
 266         }
 267         else {
 268                 name = sec_name(sym->st_shndx);
 269         }
 270         return name;
 271 }
 272
 273 static Elf_Sym *sym_lookup(const char *symname)
 274 {
 275         int i;
 276         for (i = 0; i < shnum; i++) {
 277                 struct section *sec = &secs[i];
 278                 long nsyms;
 279                 char *strtab;
 280                 Elf_Sym *symtab;
 281                 Elf_Sym *sym;
 282
 283                 if (sec->shdr.sh_type != SHT_SYMTAB)
 284                         continue;
 285
 286                 nsyms = sec->shdr.sh_size/sizeof(Elf_Sym);
 287                 symtab = sec->symtab;
 288                 strtab = sec->link->strtab;
 289
 290                 for (sym = symtab; --nsyms >= 0; sym++) {
 291                         if (!sym->st_name)
 292                                 continue;
 293                         if (strcmp(symname, strtab + sym->st_name) == 0)
 294                                 return sym;
 295                 }
 296         }
 297         return 0;
 298 }
 299
 300 #if BYTE_ORDER == LITTLE_ENDIAN
 301 #define le16_to_cpu(val) (val)
 302 #define le32_to_cpu(val) (val)
 303 #define le64_to_cpu(val) (val)
 304 #endif
 305 #if BYTE_ORDER == BIG_ENDIAN
 306 #define le16_to_cpu(val) bswap_16(val)
 307 #define le32_to_cpu(val) bswap_32(val)
 308 #define le64_to_cpu(val) bswap_64(val)
 309 #endif
 310
 311 static uint16_t elf16_to_cpu(uint16_t val)
 312 {
 313         return le16_to_cpu(val);
 314 }
 315
 316 static uint32_t elf32_to_cpu(uint32_t val)
 317 {
 318         return le32_to_cpu(val);
 319 }
 320
 321 #define elf_half_to_cpu(x)      elf16_to_cpu(x)
 322 #define elf_word_to_cpu(x)      elf32_to_cpu(x)
 323
 324 #if ELF_BITS == 64
 325 static uint64_t elf64_to_cpu(uint64_t val)
 326 {
 327         return le64_to_cpu(val);
 328 }
 329 #define elf_addr_to_cpu(x)      elf64_to_cpu(x)
 330 #define elf_off_to_cpu(x)       elf64_to_cpu(x)
 331 #define elf_xword_to_cpu(x)     elf64_to_cpu(x)
 332 #else
 333 #define elf_addr_to_cpu(x)      elf32_to_cpu(x)
 334 #define elf_off_to_cpu(x)       elf32_to_cpu(x)
 335 #define elf_xword_to_cpu(x)     elf32_to_cpu(x)
 336 #endif
 337
 338 static void read_ehdr(FILE *fp)
 339 {
 340         if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
 341                 die("Cannot read ELF header: %s\n",
 342                         strerror(errno));
 343         }
 344         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
 345                 die("No ELF magic\n");
 346         }
 347         if (ehdr.e_ident[EI_CLASS] != ELF_CLASS) {
 348                 die("Not a %d bit executable\n", ELF_BITS);
 349         }
 350         if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
 351                 die("Not a LSB ELF executable\n");
 352         }
 353         if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
 354                 die("Unknown ELF version\n");
 355         }
 356         /* Convert the fields to native endian */
 357         ehdr.e_type      = elf_half_to_cpu(ehdr.e_type);
 358         ehdr.e_machine   = elf_half_to_cpu(ehdr.e_machine);
 359         ehdr.e_version   = elf_word_to_cpu(ehdr.e_version);
 360         ehdr.e_entry     = elf_addr_to_cpu(ehdr.e_entry);
 361         ehdr.e_phoff     = elf_off_to_cpu(ehdr.e_phoff);
 362         ehdr.e_shoff     = elf_off_to_cpu(ehdr.e_shoff);
 363         ehdr.e_flags     = elf_word_to_cpu(ehdr.e_flags);
 364         ehdr.e_ehsize    = elf_half_to_cpu(ehdr.e_ehsize);
 365         ehdr.e_phentsize = elf_half_to_cpu(ehdr.e_phentsize);
 366         ehdr.e_phnum     = elf_half_to_cpu(ehdr.e_phnum);
 367         ehdr.e_shentsize = elf_half_to_cpu(ehdr.e_shentsize);
 368         ehdr.e_shnum     = elf_half_to_cpu(ehdr.e_shnum);
 369         ehdr.e_shstrndx  = elf_half_to_cpu(ehdr.e_shstrndx);
 370
 371         shnum = ehdr.e_shnum;
 372         shstrndx = ehdr.e_shstrndx;
 373
 374         if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN))
 375                 die("Unsupported ELF header type\n");
 376         if (ehdr.e_machine != ELF_MACHINE)
 377                 die("Not for %s\n", ELF_MACHINE_NAME);
 378         if (ehdr.e_version != EV_CURRENT)
 379                 die("Unknown ELF version\n");
 380         if (ehdr.e_ehsize != sizeof(Elf_Ehdr))
 381                 die("Bad Elf header size\n");
 382         if (ehdr.e_phentsize != sizeof(Elf_Phdr))
 383                 die("Bad program header entry\n");
 384         if (ehdr.e_shentsize != sizeof(Elf_Shdr))
 385                 die("Bad section header entry\n");
 386
 387
 388         if (shnum == SHN_UNDEF || shstrndx == SHN_XINDEX) {
 389                 Elf_Shdr shdr;
 390
 391                 if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0)
 392                         die("Seek to %d failed: %s\n", ehdr.e_shoff, strerror(errno));
 393
 394                 if (fread(&shdr, sizeof(shdr), 1, fp) != 1)
 395                         die("Cannot read initial ELF section header: %s\n", strerror(errno));
 396
 397                 if (shnum == SHN_UNDEF)
 398                         shnum = elf_xword_to_cpu(shdr.sh_size);
 399
 400                 if (shstrndx == SHN_XINDEX)
 401                         shstrndx = elf_word_to_cpu(shdr.sh_link);
 402         }
 403
 404         if (shstrndx >= shnum)
 405                 die("String table index out of bounds\n");
 406 }
 407
 408 static void read_shdrs(FILE *fp)
 409 {
 410         int i;
 411         Elf_Shdr shdr;
 412
 413         secs = calloc(shnum, sizeof(struct section));
 414         if (!secs) {
 415                 die("Unable to allocate %d section headers\n",
 416                     shnum);
 417         }
 418         if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
 419                 die("Seek to %d failed: %s\n",
 420                         ehdr.e_shoff, strerror(errno));
 421         }
 422         for (i = 0; i < shnum; i++) {
 423                 struct section *sec = &secs[i];
 424                 if (fread(&shdr, sizeof(shdr), 1, fp) != 1)
 425                         die("Cannot read ELF section headers %d/%d: %s\n",
 426                             i, shnum, strerror(errno));
 427                 sec->shdr.sh_name      = elf_word_to_cpu(shdr.sh_name);
 428                 sec->shdr.sh_type      = elf_word_to_cpu(shdr.sh_type);
 429                 sec->shdr.sh_flags     = elf_xword_to_cpu(shdr.sh_flags);
 430                 sec->shdr.sh_addr      = elf_addr_to_cpu(shdr.sh_addr);
 431                 sec->shdr.sh_offset    = elf_off_to_cpu(shdr.sh_offset);
 432                 sec->shdr.sh_size      = elf_xword_to_cpu(shdr.sh_size);
 433                 sec->shdr.sh_link      = elf_word_to_cpu(shdr.sh_link);
 434                 sec->shdr.sh_info      = elf_word_to_cpu(shdr.sh_info);
 435                 sec->shdr.sh_addralign = elf_xword_to_cpu(shdr.sh_addralign);
 436                 sec->shdr.sh_entsize   = elf_xword_to_cpu(shdr.sh_entsize);
 437                 if (sec->shdr.sh_link < shnum)
 438                         sec->link = &secs[sec->shdr.sh_link];
 439         }
 440
 441 }
 442
 443 static void read_strtabs(FILE *fp)
 444 {
 445         int i;
 446         for (i = 0; i < shnum; i++) {
 447                 struct section *sec = &secs[i];
 448                 if (sec->shdr.sh_type != SHT_STRTAB) {
 449                         continue;
 450                 }
 451                 sec->strtab = malloc(sec->shdr.sh_size);
 452                 if (!sec->strtab) {
 453                         die("malloc of %d bytes for strtab failed\n",
 454                                 sec->shdr.sh_size);
 455                 }
 456                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 457                         die("Seek to %d failed: %s\n",
 458                                 sec->shdr.sh_offset, strerror(errno));
 459                 }
 460                 if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
 461                     != sec->shdr.sh_size) {
 462                         die("Cannot read symbol table: %s\n",
 463                                 strerror(errno));
 464                 }
 465         }
 466 }
 467
 468 static void read_symtabs(FILE *fp)
 469 {
 470         int i,j;
 471         for (i = 0; i < shnum; i++) {
 472                 struct section *sec = &secs[i];
 473                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 474                         continue;
 475                 }
 476                 sec->symtab = malloc(sec->shdr.sh_size);
 477                 if (!sec->symtab) {
 478                         die("malloc of %d bytes for symtab failed\n",
 479                                 sec->shdr.sh_size);
 480                 }
 481                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 482                         die("Seek to %d failed: %s\n",
 483                                 sec->shdr.sh_offset, strerror(errno));
 484                 }
 485                 if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
 486                     != sec->shdr.sh_size) {
 487                         die("Cannot read symbol table: %s\n",
 488                                 strerror(errno));
 489                 }
 490                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
 491                         Elf_Sym *sym = &sec->symtab[j];
 492                         sym->st_name  = elf_word_to_cpu(sym->st_name);
 493                         sym->st_value = elf_addr_to_cpu(sym->st_value);
 494                         sym->st_size  = elf_xword_to_cpu(sym->st_size);
 495                         sym->st_shndx = elf_half_to_cpu(sym->st_shndx);
 496                 }
 497         }
 498 }
 499
 500
 501 static void read_relocs(FILE *fp)
 502 {
 503         int i,j;
 504         for (i = 0; i < shnum; i++) {
 505                 struct section *sec = &secs[i];
 506                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 507                         continue;
 508                 }
 509                 sec->reltab = malloc(sec->shdr.sh_size);
 510                 if (!sec->reltab) {
 511                         die("malloc of %d bytes for relocs failed\n",
 512                                 sec->shdr.sh_size);
 513                 }
 514                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 515                         die("Seek to %d failed: %s\n",
 516                                 sec->shdr.sh_offset, strerror(errno));
 517                 }
 518                 if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
 519                     != sec->shdr.sh_size) {
 520                         die("Cannot read symbol table: %s\n",
 521                                 strerror(errno));
 522                 }
 523                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 524                         Elf_Rel *rel = &sec->reltab[j];
 525                         rel->r_offset = elf_addr_to_cpu(rel->r_offset);
 526                         rel->r_info   = elf_xword_to_cpu(rel->r_info);
 527 #if (SHT_REL_TYPE == SHT_RELA)
 528                         rel->r_addend = elf_xword_to_cpu(rel->r_addend);
 529 #endif
 530                 }
 531         }
 532 }
 533
 534
 535 static void print_absolute_symbols(void)
 536 {
 537         int i;
 538         const char *format;
 539
 540         if (ELF_BITS == 64)
 541                 format = "%5d %016"PRIx64" %5"PRId64" %10s %10s %12s %s\n";
 542         else
 543                 format = "%5d %08"PRIx32"  %5"PRId32" %10s %10s %12s %s\n";
 544
 545         printf("Absolute symbols\n");
 546         printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
 547         for (i = 0; i < shnum; i++) {
 548                 struct section *sec = &secs[i];
 549                 char *sym_strtab;
 550                 int j;
 551
 552                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 553                         continue;
 554                 }
 555                 sym_strtab = sec->link->strtab;
 556                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
 557                         Elf_Sym *sym;
 558                         const char *name;
 559                         sym = &sec->symtab[j];
 560                         name = sym_name(sym_strtab, sym);
 561                         if (sym->st_shndx != SHN_ABS) {
 562                                 continue;
 563                         }
 564                         printf(format,
 565                                 j, sym->st_value, sym->st_size,
 566                                 sym_type(ELF_ST_TYPE(sym->st_info)),
 567                                 sym_bind(ELF_ST_BIND(sym->st_info)),
 568                                 sym_visibility(ELF_ST_VISIBILITY(sym->st_other)),
 569                                 name);
 570                 }
 571         }
 572         printf("\n");
 573 }
 574
 575 static void print_absolute_relocs(void)
 576 {
 577         int i, printed = 0;
 578         const char *format;
 579
 580         if (ELF_BITS == 64)
 581                 format = "%016"PRIx64" %016"PRIx64" %10s %016"PRIx64"  %s\n";
 582         else
 583                 format = "%08"PRIx32" %08"PRIx32" %10s %08"PRIx32"  %s\n";
 584
 585         for (i = 0; i < shnum; i++) {
 586                 struct section *sec = &secs[i];
 587                 struct section *sec_applies, *sec_symtab;
 588                 char *sym_strtab;
 589                 Elf_Sym *sh_symtab;
 590                 int j;
 591                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 592                         continue;
 593                 }
 594                 sec_symtab  = sec->link;
 595                 sec_applies = &secs[sec->shdr.sh_info];
 596                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 597                         continue;
 598                 }
 599                 /*
 600                  * Do not perform relocations in .notes section; any
 601                  * values there are meant for pre-boot consumption (e.g.
 602                  * startup_xen).
 603                  */
 604                 if (sec_applies->shdr.sh_type == SHT_NOTE) {
 605                         continue;
 606                 }
 607                 sh_symtab  = sec_symtab->symtab;
 608                 sym_strtab = sec_symtab->link->strtab;
 609                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 610                         Elf_Rel *rel;
 611                         Elf_Sym *sym;
 612                         const char *name;
 613                         rel = &sec->reltab[j];
 614                         sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
 615                         name = sym_name(sym_strtab, sym);
 616                         if (sym->st_shndx != SHN_ABS) {
 617                                 continue;
 618                         }
 619
 620                         /* Absolute symbols are not relocated if bzImage is
 621                          * loaded at a non-compiled address. Display a warning
 622                          * to user at compile time about the absolute
 623                          * relocations present.
 624                          *
 625                          * User need to audit the code to make sure
 626                          * some symbols which should have been section
 627                          * relative have not become absolute because of some
 628                          * linker optimization or wrong programming usage.
 629                          *
 630                          * Before warning check if this absolute symbol
 631                          * relocation is harmless.
 632                          */
 633                         if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
 634                                 continue;
 635
 636                         if (!printed) {
 637                                 printf("WARNING: Absolute relocations"
 638                                         " present\n");
 639                                 printf("Offset     Info     Type     Sym.Value "
 640                                         "Sym.Name\n");
 641                                 printed = 1;
 642                         }
 643
 644                         printf(format,
 645                                 rel->r_offset,
 646                                 rel->r_info,
 647                                 rel_type(ELF_R_TYPE(rel->r_info)),
 648                                 sym->st_value,
 649                                 name);
 650                 }
 651         }
 652
 653         if (printed)
 654                 printf("\n");
 655 }
 656
 657 static void add_reloc(struct relocs *r, uint32_t offset)
 658 {
 659         if (r->count == r->size) {
 660                 unsigned long newsize = r->size + 50000;
 661                 void *mem = realloc(r->offset, newsize * sizeof(r->offset[0]));
 662
 663                 if (!mem)
 664                         die("realloc of %ld entries for relocs failed\n",
 665                                 newsize);
 666                 r->offset = mem;
 667                 r->size = newsize;
 668         }
 669         r->offset[r->count++] = offset;
 670 }
 671
 672 static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
 673                         Elf_Sym *sym, const char *symname))
 674 {
 675         int i;
 676         /* Walk through the relocations */
 677         for (i = 0; i < shnum; i++) {
 678                 char *sym_strtab;
 679                 Elf_Sym *sh_symtab;
 680                 struct section *sec_applies, *sec_symtab;
 681                 int j;
 682                 struct section *sec = &secs[i];
 683
 684                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 685                         continue;
 686                 }
 687                 sec_symtab  = sec->link;
 688                 sec_applies = &secs[sec->shdr.sh_info];
 689                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 690                         continue;
 691                 }
 692                 sh_symtab = sec_symtab->symtab;
 693                 sym_strtab = sec_symtab->link->strtab;
 694                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 695                         Elf_Rel *rel = &sec->reltab[j];
 696                         Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
 697                         const char *symname = sym_name(sym_strtab, sym);
 698
 699                         process(sec, rel, sym, symname);
 700                 }
 701         }
 702 }
 703
 704 /*
 705  * The .data..percpu section is a special case for x86_64 SMP kernels.
 706  * It is used to initialize the actual per_cpu areas and to provide
 707  * definitions for the per_cpu variables that correspond to their offsets
 708  * within the percpu area. Since the values of all of the symbols need
 709  * to be offsets from the start of the per_cpu area the virtual address
 710  * (sh_addr) of .data..percpu is 0 in SMP kernels.
 711  *
 712  * This means that:
 713  *
 714  *      Relocations that reference symbols in the per_cpu area do not
 715  *      need further relocation (since the value is an offset relative
 716  *      to the start of the per_cpu area that does not change).
 717  *
 718  *      Relocations that apply to the per_cpu area need to have their
 719  *      offset adjusted by by the value of __per_cpu_load to make them
 720  *      point to the correct place in the loaded image (because the
 721  *      virtual address of .data..percpu is 0).
 722  *
 723  * For non SMP kernels .data..percpu is linked as part of the normal
 724  * kernel data and does not require special treatment.
 725  *
 726  */
 727 static int per_cpu_shndx        = -1;
 728 static Elf_Addr per_cpu_load_addr;
 729
 730 static void percpu_init(void)
 731 {
 732         int i;
 733         for (i = 0; i < shnum; i++) {
 734                 ElfW(Sym) *sym;
 735                 if (strcmp(sec_name(i), ".data..percpu"))
 736                         continue;
 737
 738                 if (secs[i].shdr.sh_addr != 0)  /* non SMP kernel */
 739                         return;
 740
 741                 sym = sym_lookup("__per_cpu_load");
 742                 if (!sym)
 743                         die("can't find __per_cpu_load\n");
 744
 745                 per_cpu_shndx = i;
 746                 per_cpu_load_addr = sym->st_value;
 747                 return;
 748         }
 749 }
 750
 751 #if ELF_BITS == 64
 752
 753 /*
 754  * Check to see if a symbol lies in the .data..percpu section.
 755  *
 756  * The linker incorrectly associates some symbols with the
 757  * .data..percpu section so we also need to check the symbol
 758  * name to make sure that we classify the symbol correctly.
 759  *
 760  * The GNU linker incorrectly associates:
 761  *      __init_begin
 762  *      __per_cpu_load
 763  *
 764  * The "gold" linker incorrectly associates:
 765  *      init_per_cpu__fixed_percpu_data
 766  *      init_per_cpu__gdt_page
 767  */
 768 static int is_percpu_sym(ElfW(Sym) *sym, const char *symname)
 769 {
 770         return (sym->st_shndx == per_cpu_shndx) &&
 771                 strcmp(symname, "__init_begin") &&
 772                 strcmp(symname, "__per_cpu_load") &&
 773                 strncmp(symname, "init_per_cpu_", 13);
 774 }
 775
 776
 777 static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
 778                       const char *symname)
 779 {
 780         unsigned r_type = ELF64_R_TYPE(rel->r_info);
 781         ElfW(Addr) offset = rel->r_offset;
 782         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 783
 784         if (sym->st_shndx == SHN_UNDEF)
 785                 return 0;
 786
 787         /*
 788          * Adjust the offset if this reloc applies to the percpu section.
 789          */
 790         if (sec->shdr.sh_info == per_cpu_shndx)
 791                 offset += per_cpu_load_addr;
 792
 793         switch (r_type) {
 794         case R_X86_64_NONE:
 795                 /* NONE can be ignored. */
 796                 break;
 797
 798         case R_X86_64_PC32:
 799         case R_X86_64_PLT32:
 800                 /*
 801                  * PC relative relocations don't need to be adjusted unless
 802                  * referencing a percpu symbol.
 803                  *
 804                  * NB: R_X86_64_PLT32 can be treated as R_X86_64_PC32.
 805                  */
 806                 if (is_percpu_sym(sym, symname))
 807                         add_reloc(&relocs32neg, offset);
 808                 break;
 809
 810         case R_X86_64_PC64:
 811                 /*
 812                  * Only used by jump labels
 813                  */
 814                 if (is_percpu_sym(sym, symname))
 815                         die("Invalid R_X86_64_PC64 relocation against per-CPU symbol %s\n",
 816                             symname);
 817                 break;
 818
 819         case R_X86_64_32:
 820         case R_X86_64_32S:
 821         case R_X86_64_64:
 822                 /*
 823                  * References to the percpu area don't need to be adjusted.
 824                  */
 825                 if (is_percpu_sym(sym, symname))
 826                         break;
 827
 828                 if (shn_abs) {
 829                         /*
 830                          * Whitelisted absolute symbols do not require
 831                          * relocation.
 832                          */
 833                         if (is_reloc(S_ABS, symname))
 834                                 break;
 835
 836                         die("Invalid absolute %s relocation: %s\n",
 837                             rel_type(r_type), symname);
 838                         break;
 839                 }
 840
 841                 /*
 842                  * Relocation offsets for 64 bit kernels are output
 843                  * as 32 bits and sign extended back to 64 bits when
 844                  * the relocations are processed.
 845                  * Make sure that the offset will fit.
 846                  */
 847                 if ((int32_t)offset != (int64_t)offset)
 848                         die("Relocation offset doesn't fit in 32 bits\n");
 849
 850                 if (r_type == R_X86_64_64)
 851                         add_reloc(&relocs64, offset);
 852                 else
 853                         add_reloc(&relocs32, offset);
 854                 break;
 855
 856         default:
 857                 die("Unsupported relocation type: %s (%d)\n",
 858                     rel_type(r_type), r_type);
 859                 break;
 860         }
 861
 862         return 0;
 863 }
 864
 865 #else
 866
 867 static int do_reloc32(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 868                       const char *symname)
 869 {
 870         unsigned r_type = ELF32_R_TYPE(rel->r_info);
 871         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 872
 873         switch (r_type) {
 874         case R_386_NONE:
 875         case R_386_PC32:
 876         case R_386_PC16:
 877         case R_386_PC8:
 878         case R_386_PLT32:
 879                 /*
 880                  * NONE can be ignored and PC relative relocations don't need
 881                  * to be adjusted. Because sym must be defined, R_386_PLT32 can
 882                  * be treated the same way as R_386_PC32.
 883                  */
 884                 break;
 885
 886         case R_386_32:
 887                 if (shn_abs) {
 888                         /*
 889                          * Whitelisted absolute symbols do not require
 890                          * relocation.
 891                          */
 892                         if (is_reloc(S_ABS, symname))
 893                                 break;
 894
 895                         die("Invalid absolute %s relocation: %s\n",
 896                             rel_type(r_type), symname);
 897                         break;
 898                 }
 899
 900                 add_reloc(&relocs32, rel->r_offset);
 901                 break;
 902
 903         default:
 904                 die("Unsupported relocation type: %s (%d)\n",
 905                     rel_type(r_type), r_type);
 906                 break;
 907         }
 908
 909         return 0;
 910 }
 911
 912 static int do_reloc_real(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 913                          const char *symname)
 914 {
 915         unsigned r_type = ELF32_R_TYPE(rel->r_info);
 916         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 917
 918         switch (r_type) {
 919         case R_386_NONE:
 920         case R_386_PC32:
 921         case R_386_PC16:
 922         case R_386_PC8:
 923         case R_386_PLT32:
 924                 /*
 925                  * NONE can be ignored and PC relative relocations don't need
 926                  * to be adjusted. Because sym must be defined, R_386_PLT32 can
 927                  * be treated the same way as R_386_PC32.
 928                  */
 929                 break;
 930
 931         case R_386_16:
 932                 if (shn_abs) {
 933                         /*
 934                          * Whitelisted absolute symbols do not require
 935                          * relocation.
 936                          */
 937                         if (is_reloc(S_ABS, symname))
 938                                 break;
 939
 940                         if (is_reloc(S_SEG, symname)) {
 941                                 add_reloc(&relocs16, rel->r_offset);
 942                                 break;
 943                         }
 944                 } else {
 945                         if (!is_reloc(S_LIN, symname))
 946                                 break;
 947                 }
 948                 die("Invalid %s %s relocation: %s\n",
 949                     shn_abs ? "absolute" : "relative",
 950                     rel_type(r_type), symname);
 951                 break;
 952
 953         case R_386_32:
 954                 if (shn_abs) {
 955                         /*
 956                          * Whitelisted absolute symbols do not require
 957                          * relocation.
 958                          */
 959                         if (is_reloc(S_ABS, symname))
 960                                 break;
 961
 962                         if (is_reloc(S_REL, symname)) {
 963                                 add_reloc(&relocs32, rel->r_offset);
 964                                 break;
 965                         }
 966                 } else {
 967                         if (is_reloc(S_LIN, symname))
 968                                 add_reloc(&relocs32, rel->r_offset);
 969                         break;
 970                 }
 971                 die("Invalid %s %s relocation: %s\n",
 972                     shn_abs ? "absolute" : "relative",
 973                     rel_type(r_type), symname);
 974                 break;
 975
 976         default:
 977                 die("Unsupported relocation type: %s (%d)\n",
 978                     rel_type(r_type), r_type);
 979                 break;
 980         }
 981
 982         return 0;
 983 }
 984
 985 #endif
 986
 987 static int cmp_relocs(const void *va, const void *vb)
 988 {
 989         const uint32_t *a, *b;
 990         a = va; b = vb;
 991         return (*a == *b)? 0 : (*a > *b)? 1 : -1;
 992 }
 993
 994 static void sort_relocs(struct relocs *r)
 995 {
 996         qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
 997 }
 998
 999 static int write32(uint32_t v, FILE *f)
1000 {
1001         unsigned char buf[4];
1002
1003         put_unaligned_le32(v, buf);
1004         return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
1005 }
1006
1007 static int write32_as_text(uint32_t v, FILE *f)
1008 {
1009         return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
1010 }
1011
1012 static void emit_relocs(int as_text, int use_real_mode)
1013 {
1014         int i;
1015         int (*write_reloc)(uint32_t, FILE *) = write32;
1016         int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
1017                         const char *symname);
1018
1019 #if ELF_BITS == 64
1020         if (!use_real_mode)
1021                 do_reloc = do_reloc64;
1022         else
1023                 die("--realmode not valid for a 64-bit ELF file");
1024 #else
1025         if (!use_real_mode)
1026                 do_reloc = do_reloc32;
1027         else
1028                 do_reloc = do_reloc_real;
1029 #endif
1030
1031         /* Collect up the relocations */
1032         walk_relocs(do_reloc);
1033
1034         if (relocs16.count && !use_real_mode)
1035                 die("Segment relocations found but --realmode not specified\n");
1036
1037         /* Order the relocations for more efficient processing */
1038         sort_relocs(&relocs32);
1039 #if ELF_BITS == 64
1040         sort_relocs(&relocs32neg);
1041         sort_relocs(&relocs64);
1042 #else
1043         sort_relocs(&relocs16);
1044 #endif
1045
1046         /* Print the relocations */
1047         if (as_text) {
1048                 /* Print the relocations in a form suitable that
1049                  * gas will like.
1050                  */
1051                 printf(".section \".data.reloc\",\"a\"\n");
1052                 printf(".balign 4\n");
1053                 write_reloc = write32_as_text;
1054         }
1055
1056         if (use_real_mode) {
1057                 write_reloc(relocs16.count, stdout);
1058                 for (i = 0; i < relocs16.count; i++)
1059                         write_reloc(relocs16.offset[i], stdout);
1060
1061                 write_reloc(relocs32.count, stdout);
1062                 for (i = 0; i < relocs32.count; i++)
1063                         write_reloc(relocs32.offset[i], stdout);
1064         } else {
1065 #if ELF_BITS == 64
1066                 /* Print a stop */
1067                 write_reloc(0, stdout);
1068
1069                 /* Now print each relocation */
1070                 for (i = 0; i < relocs64.count; i++)
1071                         write_reloc(relocs64.offset[i], stdout);
1072
1073                 /* Print a stop */
1074                 write_reloc(0, stdout);
1075
1076                 /* Now print each inverse 32-bit relocation */
1077                 for (i = 0; i < relocs32neg.count; i++)
1078                         write_reloc(relocs32neg.offset[i], stdout);
1079 #endif
1080
1081                 /* Print a stop */
1082                 write_reloc(0, stdout);
1083
1084                 /* Now print each relocation */
1085                 for (i = 0; i < relocs32.count; i++)
1086                         write_reloc(relocs32.offset[i], stdout);
1087         }
1088 }
1089
1090 /*
1091  * As an aid to debugging problems with different linkers
1092  * print summary information about the relocs.
1093  * Since different linkers tend to emit the sections in
1094  * different orders we use the section names in the output.
1095  */
1096 static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
1097                                 const char *symname)
1098 {
1099         printf("%s\t%s\t%s\t%s\n",
1100                 sec_name(sec->shdr.sh_info),
1101                 rel_type(ELF_R_TYPE(rel->r_info)),
1102                 symname,
1103                 sec_name(sym->st_shndx));
1104         return 0;
1105 }
1106
1107 static void print_reloc_info(void)
1108 {
1109         printf("reloc section\treloc type\tsymbol\tsymbol section\n");
1110         walk_relocs(do_reloc_info);
1111 }
1112
1113 #if ELF_BITS == 64
1114 # define process process_64
1115 #else
1116 # define process process_32
1117 #endif
1118
1119 void process(FILE *fp, int use_real_mode, int as_text,
1120              int show_absolute_syms, int show_absolute_relocs,
1121              int show_reloc_info)
1122 {
1123         regex_init(use_real_mode);
1124         read_ehdr(fp);
1125         read_shdrs(fp);
1126         read_strtabs(fp);
1127         read_symtabs(fp);
1128         read_relocs(fp);
1129         if (ELF_BITS == 64)
1130                 percpu_init();
1131         if (show_absolute_syms) {
1132                 print_absolute_symbols();
1133                 return;
1134         }
1135         if (show_absolute_relocs) {
1136                 print_absolute_relocs();
1137                 return;
1138         }
1139         if (show_reloc_info) {
1140                 print_reloc_info();
1141                 return;
1142         }
1143         emit_relocs(as_text, use_real_mode);
1144 }