arch/x86/tools/relocs.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
is_reloc
regex_init
sym_type
sym_bind
sym_visibility
rel_type
sec_name
sym_name
sym_lookup
elf16_to_cpu
elf32_to_cpu
elf64_to_cpu
read_ehdr
read_shdrs
read_strtabs
read_symtabs
read_relocs
print_absolute_symbols
print_absolute_relocs
add_reloc
walk_relocs
percpu_init
is_percpu_sym
do_reloc64
do_reloc32
do_reloc_real
cmp_relocs
sort_relocs
write32
write32_as_text
emit_relocs
do_reloc_info
print_reloc_info
process
   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                 sh_symtab  = sec_symtab->symtab;
 600                 sym_strtab = sec_symtab->link->strtab;
 601                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 602                         Elf_Rel *rel;
 603                         Elf_Sym *sym;
 604                         const char *name;
 605                         rel = &sec->reltab[j];
 606                         sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
 607                         name = sym_name(sym_strtab, sym);
 608                         if (sym->st_shndx != SHN_ABS) {
 609                                 continue;
 610                         }
 611 
 612                         /* Absolute symbols are not relocated if bzImage is
 613                          * loaded at a non-compiled address. Display a warning
 614                          * to user at compile time about the absolute
 615                          * relocations present.
 616                          *
 617                          * User need to audit the code to make sure
 618                          * some symbols which should have been section
 619                          * relative have not become absolute because of some
 620                          * linker optimization or wrong programming usage.
 621                          *
 622                          * Before warning check if this absolute symbol
 623                          * relocation is harmless.
 624                          */
 625                         if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
 626                                 continue;
 627 
 628                         if (!printed) {
 629                                 printf("WARNING: Absolute relocations"
 630                                         " present\n");
 631                                 printf("Offset     Info     Type     Sym.Value "
 632                                         "Sym.Name\n");
 633                                 printed = 1;
 634                         }
 635 
 636                         printf(format,
 637                                 rel->r_offset,
 638                                 rel->r_info,
 639                                 rel_type(ELF_R_TYPE(rel->r_info)),
 640                                 sym->st_value,
 641                                 name);
 642                 }
 643         }
 644 
 645         if (printed)
 646                 printf("\n");
 647 }
 648 
 649 static void add_reloc(struct relocs *r, uint32_t offset)
 650 {
 651         if (r->count == r->size) {
 652                 unsigned long newsize = r->size + 50000;
 653                 void *mem = realloc(r->offset, newsize * sizeof(r->offset[0]));
 654 
 655                 if (!mem)
 656                         die("realloc of %ld entries for relocs failed\n",
 657                                 newsize);
 658                 r->offset = mem;
 659                 r->size = newsize;
 660         }
 661         r->offset[r->count++] = offset;
 662 }
 663 
 664 static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
 665                         Elf_Sym *sym, const char *symname))
 666 {
 667         int i;
 668         /* Walk through the relocations */
 669         for (i = 0; i < shnum; i++) {
 670                 char *sym_strtab;
 671                 Elf_Sym *sh_symtab;
 672                 struct section *sec_applies, *sec_symtab;
 673                 int j;
 674                 struct section *sec = &secs[i];
 675 
 676                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 677                         continue;
 678                 }
 679                 sec_symtab  = sec->link;
 680                 sec_applies = &secs[sec->shdr.sh_info];
 681                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 682                         continue;
 683                 }
 684                 sh_symtab = sec_symtab->symtab;
 685                 sym_strtab = sec_symtab->link->strtab;
 686                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 687                         Elf_Rel *rel = &sec->reltab[j];
 688                         Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
 689                         const char *symname = sym_name(sym_strtab, sym);
 690 
 691                         process(sec, rel, sym, symname);
 692                 }
 693         }
 694 }
 695 
 696 /*
 697  * The .data..percpu section is a special case for x86_64 SMP kernels.
 698  * It is used to initialize the actual per_cpu areas and to provide
 699  * definitions for the per_cpu variables that correspond to their offsets
 700  * within the percpu area. Since the values of all of the symbols need
 701  * to be offsets from the start of the per_cpu area the virtual address
 702  * (sh_addr) of .data..percpu is 0 in SMP kernels.
 703  *
 704  * This means that:
 705  *
 706  *      Relocations that reference symbols in the per_cpu area do not
 707  *      need further relocation (since the value is an offset relative
 708  *      to the start of the per_cpu area that does not change).
 709  *
 710  *      Relocations that apply to the per_cpu area need to have their
 711  *      offset adjusted by by the value of __per_cpu_load to make them
 712  *      point to the correct place in the loaded image (because the
 713  *      virtual address of .data..percpu is 0).
 714  *
 715  * For non SMP kernels .data..percpu is linked as part of the normal
 716  * kernel data and does not require special treatment.
 717  *
 718  */
 719 static int per_cpu_shndx        = -1;
 720 static Elf_Addr per_cpu_load_addr;
 721 
 722 static void percpu_init(void)
 723 {
 724         int i;
 725         for (i = 0; i < shnum; i++) {
 726                 ElfW(Sym) *sym;
 727                 if (strcmp(sec_name(i), ".data..percpu"))
 728                         continue;
 729 
 730                 if (secs[i].shdr.sh_addr != 0)  /* non SMP kernel */
 731                         return;
 732 
 733                 sym = sym_lookup("__per_cpu_load");
 734                 if (!sym)
 735                         die("can't find __per_cpu_load\n");
 736 
 737                 per_cpu_shndx = i;
 738                 per_cpu_load_addr = sym->st_value;
 739                 return;
 740         }
 741 }
 742 
 743 #if ELF_BITS == 64
 744 
 745 /*
 746  * Check to see if a symbol lies in the .data..percpu section.
 747  *
 748  * The linker incorrectly associates some symbols with the
 749  * .data..percpu section so we also need to check the symbol
 750  * name to make sure that we classify the symbol correctly.
 751  *
 752  * The GNU linker incorrectly associates:
 753  *      __init_begin
 754  *      __per_cpu_load
 755  *
 756  * The "gold" linker incorrectly associates:
 757  *      init_per_cpu__fixed_percpu_data
 758  *      init_per_cpu__gdt_page
 759  */
 760 static int is_percpu_sym(ElfW(Sym) *sym, const char *symname)
 761 {
 762         return (sym->st_shndx == per_cpu_shndx) &&
 763                 strcmp(symname, "__init_begin") &&
 764                 strcmp(symname, "__per_cpu_load") &&
 765                 strncmp(symname, "init_per_cpu_", 13);
 766 }
 767 
 768 
 769 static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
 770                       const char *symname)
 771 {
 772         unsigned r_type = ELF64_R_TYPE(rel->r_info);
 773         ElfW(Addr) offset = rel->r_offset;
 774         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 775 
 776         if (sym->st_shndx == SHN_UNDEF)
 777                 return 0;
 778 
 779         /*
 780          * Adjust the offset if this reloc applies to the percpu section.
 781          */
 782         if (sec->shdr.sh_info == per_cpu_shndx)
 783                 offset += per_cpu_load_addr;
 784 
 785         switch (r_type) {
 786         case R_X86_64_NONE:
 787                 /* NONE can be ignored. */
 788                 break;
 789 
 790         case R_X86_64_PC32:
 791         case R_X86_64_PLT32:
 792                 /*
 793                  * PC relative relocations don't need to be adjusted unless
 794                  * referencing a percpu symbol.
 795                  *
 796                  * NB: R_X86_64_PLT32 can be treated as R_X86_64_PC32.
 797                  */
 798                 if (is_percpu_sym(sym, symname))
 799                         add_reloc(&relocs32neg, offset);
 800                 break;
 801 
 802         case R_X86_64_PC64:
 803                 /*
 804                  * Only used by jump labels
 805                  */
 806                 if (is_percpu_sym(sym, symname))
 807                         die("Invalid R_X86_64_PC64 relocation against per-CPU symbol %s\n",
 808                             symname);
 809                 break;
 810 
 811         case R_X86_64_32:
 812         case R_X86_64_32S:
 813         case R_X86_64_64:
 814                 /*
 815                  * References to the percpu area don't need to be adjusted.
 816                  */
 817                 if (is_percpu_sym(sym, symname))
 818                         break;
 819 
 820                 if (shn_abs) {
 821                         /*
 822                          * Whitelisted absolute symbols do not require
 823                          * relocation.
 824                          */
 825                         if (is_reloc(S_ABS, symname))
 826                                 break;
 827 
 828                         die("Invalid absolute %s relocation: %s\n",
 829                             rel_type(r_type), symname);
 830                         break;
 831                 }
 832 
 833                 /*
 834                  * Relocation offsets for 64 bit kernels are output
 835                  * as 32 bits and sign extended back to 64 bits when
 836                  * the relocations are processed.
 837                  * Make sure that the offset will fit.
 838                  */
 839                 if ((int32_t)offset != (int64_t)offset)
 840                         die("Relocation offset doesn't fit in 32 bits\n");
 841 
 842                 if (r_type == R_X86_64_64)
 843                         add_reloc(&relocs64, offset);
 844                 else
 845                         add_reloc(&relocs32, offset);
 846                 break;
 847 
 848         default:
 849                 die("Unsupported relocation type: %s (%d)\n",
 850                     rel_type(r_type), r_type);
 851                 break;
 852         }
 853 
 854         return 0;
 855 }
 856 
 857 #else
 858 
 859 static int do_reloc32(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 860                       const char *symname)
 861 {
 862         unsigned r_type = ELF32_R_TYPE(rel->r_info);
 863         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 864 
 865         switch (r_type) {
 866         case R_386_NONE:
 867         case R_386_PC32:
 868         case R_386_PC16:
 869         case R_386_PC8:
 870                 /*
 871                  * NONE can be ignored and PC relative relocations don't
 872                  * need to be adjusted.
 873                  */
 874                 break;
 875 
 876         case R_386_32:
 877                 if (shn_abs) {
 878                         /*
 879                          * Whitelisted absolute symbols do not require
 880                          * relocation.
 881                          */
 882                         if (is_reloc(S_ABS, symname))
 883                                 break;
 884 
 885                         die("Invalid absolute %s relocation: %s\n",
 886                             rel_type(r_type), symname);
 887                         break;
 888                 }
 889 
 890                 add_reloc(&relocs32, rel->r_offset);
 891                 break;
 892 
 893         default:
 894                 die("Unsupported relocation type: %s (%d)\n",
 895                     rel_type(r_type), r_type);
 896                 break;
 897         }
 898 
 899         return 0;
 900 }
 901 
 902 static int do_reloc_real(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 903                          const char *symname)
 904 {
 905         unsigned r_type = ELF32_R_TYPE(rel->r_info);
 906         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 907 
 908         switch (r_type) {
 909         case R_386_NONE:
 910         case R_386_PC32:
 911         case R_386_PC16:
 912         case R_386_PC8:
 913                 /*
 914                  * NONE can be ignored and PC relative relocations don't
 915                  * need to be adjusted.
 916                  */
 917                 break;
 918 
 919         case R_386_16:
 920                 if (shn_abs) {
 921                         /*
 922                          * Whitelisted absolute symbols do not require
 923                          * relocation.
 924                          */
 925                         if (is_reloc(S_ABS, symname))
 926                                 break;
 927 
 928                         if (is_reloc(S_SEG, symname)) {
 929                                 add_reloc(&relocs16, rel->r_offset);
 930                                 break;
 931                         }
 932                 } else {
 933                         if (!is_reloc(S_LIN, symname))
 934                                 break;
 935                 }
 936                 die("Invalid %s %s relocation: %s\n",
 937                     shn_abs ? "absolute" : "relative",
 938                     rel_type(r_type), symname);
 939                 break;
 940 
 941         case R_386_32:
 942                 if (shn_abs) {
 943                         /*
 944                          * Whitelisted absolute symbols do not require
 945                          * relocation.
 946                          */
 947                         if (is_reloc(S_ABS, symname))
 948                                 break;
 949 
 950                         if (is_reloc(S_REL, symname)) {
 951                                 add_reloc(&relocs32, rel->r_offset);
 952                                 break;
 953                         }
 954                 } else {
 955                         if (is_reloc(S_LIN, symname))
 956                                 add_reloc(&relocs32, rel->r_offset);
 957                         break;
 958                 }
 959                 die("Invalid %s %s relocation: %s\n",
 960                     shn_abs ? "absolute" : "relative",
 961                     rel_type(r_type), symname);
 962                 break;
 963 
 964         default:
 965                 die("Unsupported relocation type: %s (%d)\n",
 966                     rel_type(r_type), r_type);
 967                 break;
 968         }
 969 
 970         return 0;
 971 }
 972 
 973 #endif
 974 
 975 static int cmp_relocs(const void *va, const void *vb)
 976 {
 977         const uint32_t *a, *b;
 978         a = va; b = vb;
 979         return (*a == *b)? 0 : (*a > *b)? 1 : -1;
 980 }
 981 
 982 static void sort_relocs(struct relocs *r)
 983 {
 984         qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
 985 }
 986 
 987 static int write32(uint32_t v, FILE *f)
 988 {
 989         unsigned char buf[4];
 990 
 991         put_unaligned_le32(v, buf);
 992         return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
 993 }
 994 
 995 static int write32_as_text(uint32_t v, FILE *f)
 996 {
 997         return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
 998 }
 999 
1000 static void emit_relocs(int as_text, int use_real_mode)
1001 {
1002         int i;
1003         int (*write_reloc)(uint32_t, FILE *) = write32;
1004         int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
1005                         const char *symname);
1006 
1007 #if ELF_BITS == 64
1008         if (!use_real_mode)
1009                 do_reloc = do_reloc64;
1010         else
1011                 die("--realmode not valid for a 64-bit ELF file");
1012 #else
1013         if (!use_real_mode)
1014                 do_reloc = do_reloc32;
1015         else
1016                 do_reloc = do_reloc_real;
1017 #endif
1018 
1019         /* Collect up the relocations */
1020         walk_relocs(do_reloc);
1021 
1022         if (relocs16.count && !use_real_mode)
1023                 die("Segment relocations found but --realmode not specified\n");
1024 
1025         /* Order the relocations for more efficient processing */
1026         sort_relocs(&relocs32);
1027 #if ELF_BITS == 64
1028         sort_relocs(&relocs32neg);
1029         sort_relocs(&relocs64);
1030 #else
1031         sort_relocs(&relocs16);
1032 #endif
1033 
1034         /* Print the relocations */
1035         if (as_text) {
1036                 /* Print the relocations in a form suitable that
1037                  * gas will like.
1038                  */
1039                 printf(".section \".data.reloc\",\"a\"\n");
1040                 printf(".balign 4\n");
1041                 write_reloc = write32_as_text;
1042         }
1043 
1044         if (use_real_mode) {
1045                 write_reloc(relocs16.count, stdout);
1046                 for (i = 0; i < relocs16.count; i++)
1047                         write_reloc(relocs16.offset[i], stdout);
1048 
1049                 write_reloc(relocs32.count, stdout);
1050                 for (i = 0; i < relocs32.count; i++)
1051                         write_reloc(relocs32.offset[i], stdout);
1052         } else {
1053 #if ELF_BITS == 64
1054                 /* Print a stop */
1055                 write_reloc(0, stdout);
1056 
1057                 /* Now print each relocation */
1058                 for (i = 0; i < relocs64.count; i++)
1059                         write_reloc(relocs64.offset[i], stdout);
1060 
1061                 /* Print a stop */
1062                 write_reloc(0, stdout);
1063 
1064                 /* Now print each inverse 32-bit relocation */
1065                 for (i = 0; i < relocs32neg.count; i++)
1066                         write_reloc(relocs32neg.offset[i], stdout);
1067 #endif
1068 
1069                 /* Print a stop */
1070                 write_reloc(0, stdout);
1071 
1072                 /* Now print each relocation */
1073                 for (i = 0; i < relocs32.count; i++)
1074                         write_reloc(relocs32.offset[i], stdout);
1075         }
1076 }
1077 
1078 /*
1079  * As an aid to debugging problems with different linkers
1080  * print summary information about the relocs.
1081  * Since different linkers tend to emit the sections in
1082  * different orders we use the section names in the output.
1083  */
1084 static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym,
1085                                 const char *symname)
1086 {
1087         printf("%s\t%s\t%s\t%s\n",
1088                 sec_name(sec->shdr.sh_info),
1089                 rel_type(ELF_R_TYPE(rel->r_info)),
1090                 symname,
1091                 sec_name(sym->st_shndx));
1092         return 0;
1093 }
1094 
1095 static void print_reloc_info(void)
1096 {
1097         printf("reloc section\treloc type\tsymbol\tsymbol section\n");
1098         walk_relocs(do_reloc_info);
1099 }
1100 
1101 #if ELF_BITS == 64
1102 # define process process_64
1103 #else
1104 # define process process_32
1105 #endif
1106 
1107 void process(FILE *fp, int use_real_mode, int as_text,
1108              int show_absolute_syms, int show_absolute_relocs,
1109              int show_reloc_info)
1110 {
1111         regex_init(use_real_mode);
1112         read_ehdr(fp);
1113         read_shdrs(fp);
1114         read_strtabs(fp);
1115         read_symtabs(fp);
1116         read_relocs(fp);
1117         if (ELF_BITS == 64)
1118                 percpu_init();
1119         if (show_absolute_syms) {
1120                 print_absolute_symbols();
1121                 return;
1122         }
1123         if (show_absolute_relocs) {
1124                 print_absolute_relocs();
1125                 return;
1126         }
1127         if (show_reloc_info) {
1128                 print_reloc_info();
1129                 return;
1130         }
1131         emit_relocs(as_text, use_real_mode);
1132 }
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root/arch/x86/tools/relocs.c

DEFINITIONS
