linux/arch/x86/tools/relocs.c
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   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
  13static Elf_Ehdr ehdr;
  14
  15struct relocs {
  16        uint32_t        *offset;
  17        unsigned long   count;
  18        unsigned long   size;
  19};
  20
  21static struct relocs relocs16;
  22static struct relocs relocs32;
  23#if ELF_BITS == 64
  24static struct relocs relocs32neg;
  25static struct relocs relocs64;
  26#endif
  27
  28struct section {
  29        Elf_Shdr       shdr;
  30        struct section *link;
  31        Elf_Sym        *symtab;
  32        Elf_Rel        *reltab;
  33        char           *strtab;
  34};
  35static struct section *secs;
  36
  37static 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)$"
  78};
  79
  80
  81static const char * const sym_regex_realmode[S_NSYMTYPES] = {
  82/*
  83 * These symbols are known to be relative, even if the linker marks them
  84 * as absolute (typically defined outside any section in the linker script.)
  85 */
  86        [S_REL] =
  87        "^pa_",
  88
  89/*
  90 * These are 16-bit segment symbols when compiling 16-bit code.
  91 */
  92        [S_SEG] =
  93        "^real_mode_seg$",
  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
 103static const char * const *sym_regex;
 104
 105static regex_t sym_regex_c[S_NSYMTYPES];
 106static 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
 112static 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
 137static 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
 157static 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
 173static 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
 190static 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
 237static 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
 255static 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
 268static 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
 306static uint16_t elf16_to_cpu(uint16_t val)
 307{
 308        return le16_to_cpu(val);
 309}
 310
 311static 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
 320static 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
 333static 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
 389static 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
 424static 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
 449static 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
 482static 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
 516static 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
 556static 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
 630static 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
 645static 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 */
 700static int per_cpu_shndx        = -1;
 701static Elf_Addr per_cpu_load_addr;
 702
 703static 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 */
 741static 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
 750static 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
 828static 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
 871static 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
 944static 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
 951static void sort_relocs(struct relocs *r)
 952{
 953        qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
 954}
 955
 956static 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
 964static 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
 969static 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(&relocs32);
 996#if ELF_BITS == 64
 997        sort_relocs(&relocs32neg);
 998        sort_relocs(&relocs64);
 999#else
1000        sort_relocs(&relocs16);
1001#endif
1002
1003        /* Print the relocations */
1004        if (as_text) {
1005                /* Print the relocations in a form suitable that
1006                 * gas will like.
1007                 */
1008                printf(".section \".data.reloc\",\"a\"\n");
1009                printf(".balign 4\n");
1010                write_reloc = write32_as_text;
1011        }
1012
1013        if (use_real_mode) {
1014                write_reloc(relocs16.count, stdout);
1015                for (i = 0; i < relocs16.count; i++)
1016                        write_reloc(relocs16.offset[i], stdout);
1017
1018                write_reloc(relocs32.count, stdout);
1019                for (i = 0; i < relocs32.count; i++)
1020                        write_reloc(relocs32.offset[i], stdout);
1021        } else {
1022#if ELF_BITS == 64
1023                /* Print a stop */
1024                write_reloc(0, stdout);
1025
1026                /* Now print each relocation */
1027                for (i = 0; i < relocs64.count; i++)
1028                        write_reloc(relocs64.offset[i], stdout);
1029
1030                /* Print a stop */
1031                write_reloc(0, stdout);
1032
1033                /* Now print each inverse 32-bit relocation */
1034                for (i = 0; i < relocs32neg.count; i++)
1035                        write_reloc(relocs32neg.offset[i], stdout);
1036#endif
1037
1038                /* Print a stop */
1039                write_reloc(0, stdout);
1040
1041                /* Now print each relocation */
1042                for (i = 0; i < relocs32.count; i++)
1043                        write_reloc(relocs32.offset[i], stdout);
1044        }
1045}
1046
1047/*
1048 * As an aid to debugging problems with different linkers
1049 * print summary information about the relocs.
1050 * Since different linkers tend to emit the sections in
1051 * different orders we use the section names in the output.
1052 */
1053static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
1054                                const char *symname)
1055{
1056        printf("%s\t%s\t%s\t%s\n",
1057                sec_name(sec->shdr.sh_info),
1058                rel_type(ELF_R_TYPE(rel->r_info)),
1059                symname,
1060                sec_name(sym->st_shndx));
1061        return 0;
1062}
1063
1064static void print_reloc_info(void)
1065{
1066        printf("reloc section\treloc type\tsymbol\tsymbol section\n");
1067        walk_relocs(do_reloc_info);
1068}
1069
1070#if ELF_BITS == 64
1071# define process process_64
1072#else
1073# define process process_32
1074#endif
1075
1076void process(FILE *fp, int use_real_mode, int as_text,
1077             int show_absolute_syms, int show_absolute_relocs,
1078             int show_reloc_info)
1079{
1080        regex_init(use_real_mode);
1081        read_ehdr(fp);
1082        read_shdrs(fp);
1083        read_strtabs(fp);
1084        read_symtabs(fp);
1085        read_relocs(fp);
1086        if (ELF_BITS == 64)
1087                percpu_init();
1088        if (show_absolute_syms) {
1089                print_absolute_symbols();
1090                return;
1091        }
1092        if (show_absolute_relocs) {
1093                print_absolute_relocs();
1094                return;
1095        }
1096        if (show_reloc_info) {
1097                print_reloc_info();
1098                return;
1099        }
1100        emit_relocs(as_text, use_real_mode);
1101}
1102