arch/x86/tools/relocs.c

   1 #include <stdio.h>
   2 #include <stdarg.h>
   3 #include <stdlib.h>
   4 #include <stdint.h>
   5 #include <inttypes.h>
   6 #include <string.h>
   7 #include <errno.h>
   8 #include <unistd.h>
   9 #include <elf.h>
  10 #include <byteswap.h>
  11 #define USE_BSD
  12 #include <endian.h>
  13 #include <regex.h>
  14 #include <tools/le_byteshift.h>
  15
  16 #define ElfW(type)              _ElfW(ELF_BITS, type)
  17 #define _ElfW(bits, type)       __ElfW(bits, type)
  18 #define __ElfW(bits, type)      Elf##bits##_##type
  19
  20 #define ELF_BITS                32
  21 #define ELF_MACHINE             EM_386
  22 #define ELF_MACHINE_NAME        "i386"
  23 #define SHT_REL_TYPE            SHT_REL
  24
  25 #define ELF_CLASS               ELFCLASS32
  26 #define ELF_R_SYM(val)          ELF32_R_SYM(val)
  27 #define ELF_R_TYPE(val)         ELF32_R_TYPE(val)
  28 #define ELF_ST_TYPE(o)          ELF32_ST_TYPE(o)
  29 #define ELF_ST_BIND(o)          ELF32_ST_BIND(o)
  30 #define ELF_ST_VISIBILITY(o)    ELF32_ST_VISIBILITY(o)
  31
  32 #define Elf_Rel                 ElfW(Rel)
  33 #define Elf_Ehdr                ElfW(Ehdr)
  34 #define Elf_Phdr                ElfW(Phdr)
  35 #define Elf_Shdr                ElfW(Shdr)
  36 #define Elf_Sym                 ElfW(Sym)
  37
  38 static void die(char *fmt, ...);
  39
  40 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
  41 static Elf_Ehdr ehdr;
  42
  43 struct relocs {
  44         uint32_t        *offset;
  45         unsigned long   count;
  46         unsigned long   size;
  47 };
  48
  49 static struct relocs relocs16;
  50 static struct relocs relocs32;
  51
  52 struct section {
  53         Elf_Shdr       shdr;
  54         struct section *link;
  55         Elf_Sym        *symtab;
  56         Elf_Rel        *reltab;
  57         char           *strtab;
  58 };
  59 static struct section *secs;
  60
  61 enum symtype {
  62         S_ABS,
  63         S_REL,
  64         S_SEG,
  65         S_LIN,
  66         S_NSYMTYPES
  67 };
  68
  69 static const char * const sym_regex_kernel[S_NSYMTYPES] = {
  70 /*
  71  * Following symbols have been audited. There values are constant and do
  72  * not change if bzImage is loaded at a different physical address than
  73  * the address for which it has been compiled. Don't warn user about
  74  * absolute relocations present w.r.t these symbols.
  75  */
  76         [S_ABS] =
  77         "^(xen_irq_disable_direct_reloc$|"
  78         "xen_save_fl_direct_reloc$|"
  79         "VDSO|"
  80         "__crc_)",
  81
  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         "^(__init_(begin|end)|"
  88         "__x86_cpu_dev_(start|end)|"
  89         "(__parainstructions|__alt_instructions)(|_end)|"
  90         "(__iommu_table|__apicdrivers|__smp_locks)(|_end)|"
  91         "__(start|end)_pci_.*|"
  92         "__(start|end)_builtin_fw|"
  93         "__(start|stop)___ksymtab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
  94         "__(start|stop)___kcrctab(|_gpl|_unused|_unused_gpl|_gpl_future)|"
  95         "__(start|stop)___param|"
  96         "__(start|stop)___modver|"
  97         "__(start|stop)___bug_table|"
  98         "__tracedata_(start|end)|"
  99         "__(start|stop)_notes|"
 100         "__end_rodata|"
 101         "__initramfs_start|"
 102         "(jiffies|jiffies_64)|"
 103         "_end)$"
 104 };
 105
 106
 107 static const char * const sym_regex_realmode[S_NSYMTYPES] = {
 108 /*
 109  * These symbols are known to be relative, even if the linker marks them
 110  * as absolute (typically defined outside any section in the linker script.)
 111  */
 112         [S_REL] =
 113         "^pa_",
 114
 115 /*
 116  * These are 16-bit segment symbols when compiling 16-bit code.
 117  */
 118         [S_SEG] =
 119         "^real_mode_seg$",
 120
 121 /*
 122  * These are offsets belonging to segments, as opposed to linear addresses,
 123  * when compiling 16-bit code.
 124  */
 125         [S_LIN] =
 126         "^pa_",
 127 };
 128
 129 static const char * const *sym_regex;
 130
 131 static regex_t sym_regex_c[S_NSYMTYPES];
 132 static int is_reloc(enum symtype type, const char *sym_name)
 133 {
 134         return sym_regex[type] &&
 135                 !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
 136 }
 137
 138 static void regex_init(int use_real_mode)
 139 {
 140         char errbuf[128];
 141         int err;
 142         int i;
 143
 144         if (use_real_mode)
 145                 sym_regex = sym_regex_realmode;
 146         else
 147                 sym_regex = sym_regex_kernel;
 148
 149         for (i = 0; i < S_NSYMTYPES; i++) {
 150                 if (!sym_regex[i])
 151                         continue;
 152
 153                 err = regcomp(&sym_regex_c[i], sym_regex[i],
 154                               REG_EXTENDED|REG_NOSUB);
 155
 156                 if (err) {
 157                         regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
 158                         die("%s", errbuf);
 159                 }
 160         }
 161 }
 162
 163 static void die(char *fmt, ...)
 164 {
 165         va_list ap;
 166         va_start(ap, fmt);
 167         vfprintf(stderr, fmt, ap);
 168         va_end(ap);
 169         exit(1);
 170 }
 171
 172 static const char *sym_type(unsigned type)
 173 {
 174         static const char *type_name[] = {
 175 #define SYM_TYPE(X) [X] = #X
 176                 SYM_TYPE(STT_NOTYPE),
 177                 SYM_TYPE(STT_OBJECT),
 178                 SYM_TYPE(STT_FUNC),
 179                 SYM_TYPE(STT_SECTION),
 180                 SYM_TYPE(STT_FILE),
 181                 SYM_TYPE(STT_COMMON),
 182                 SYM_TYPE(STT_TLS),
 183 #undef SYM_TYPE
 184         };
 185         const char *name = "unknown sym type name";
 186         if (type < ARRAY_SIZE(type_name)) {
 187                 name = type_name[type];
 188         }
 189         return name;
 190 }
 191
 192 static const char *sym_bind(unsigned bind)
 193 {
 194         static const char *bind_name[] = {
 195 #define SYM_BIND(X) [X] = #X
 196                 SYM_BIND(STB_LOCAL),
 197                 SYM_BIND(STB_GLOBAL),
 198                 SYM_BIND(STB_WEAK),
 199 #undef SYM_BIND
 200         };
 201         const char *name = "unknown sym bind name";
 202         if (bind < ARRAY_SIZE(bind_name)) {
 203                 name = bind_name[bind];
 204         }
 205         return name;
 206 }
 207
 208 static const char *sym_visibility(unsigned visibility)
 209 {
 210         static const char *visibility_name[] = {
 211 #define SYM_VISIBILITY(X) [X] = #X
 212                 SYM_VISIBILITY(STV_DEFAULT),
 213                 SYM_VISIBILITY(STV_INTERNAL),
 214                 SYM_VISIBILITY(STV_HIDDEN),
 215                 SYM_VISIBILITY(STV_PROTECTED),
 216 #undef SYM_VISIBILITY
 217         };
 218         const char *name = "unknown sym visibility name";
 219         if (visibility < ARRAY_SIZE(visibility_name)) {
 220                 name = visibility_name[visibility];
 221         }
 222         return name;
 223 }
 224
 225 static const char *rel_type(unsigned type)
 226 {
 227         static const char *type_name[] = {
 228 #define REL_TYPE(X) [X] = #X
 229                 REL_TYPE(R_386_NONE),
 230                 REL_TYPE(R_386_32),
 231                 REL_TYPE(R_386_PC32),
 232                 REL_TYPE(R_386_GOT32),
 233                 REL_TYPE(R_386_PLT32),
 234                 REL_TYPE(R_386_COPY),
 235                 REL_TYPE(R_386_GLOB_DAT),
 236                 REL_TYPE(R_386_JMP_SLOT),
 237                 REL_TYPE(R_386_RELATIVE),
 238                 REL_TYPE(R_386_GOTOFF),
 239                 REL_TYPE(R_386_GOTPC),
 240                 REL_TYPE(R_386_8),
 241                 REL_TYPE(R_386_PC8),
 242                 REL_TYPE(R_386_16),
 243                 REL_TYPE(R_386_PC16),
 244 #undef REL_TYPE
 245         };
 246         const char *name = "unknown type rel type name";
 247         if (type < ARRAY_SIZE(type_name) && type_name[type]) {
 248                 name = type_name[type];
 249         }
 250         return name;
 251 }
 252
 253 static const char *sec_name(unsigned shndx)
 254 {
 255         const char *sec_strtab;
 256         const char *name;
 257         sec_strtab = secs[ehdr.e_shstrndx].strtab;
 258         name = "<noname>";
 259         if (shndx < ehdr.e_shnum) {
 260                 name = sec_strtab + secs[shndx].shdr.sh_name;
 261         }
 262         else if (shndx == SHN_ABS) {
 263                 name = "ABSOLUTE";
 264         }
 265         else if (shndx == SHN_COMMON) {
 266                 name = "COMMON";
 267         }
 268         return name;
 269 }
 270
 271 static const char *sym_name(const char *sym_strtab, Elf_Sym *sym)
 272 {
 273         const char *name;
 274         name = "<noname>";
 275         if (sym->st_name) {
 276                 name = sym_strtab + sym->st_name;
 277         }
 278         else {
 279                 name = sec_name(sym->st_shndx);
 280         }
 281         return name;
 282 }
 283
 284
 285
 286 #if BYTE_ORDER == LITTLE_ENDIAN
 287 #define le16_to_cpu(val) (val)
 288 #define le32_to_cpu(val) (val)
 289 #endif
 290 #if BYTE_ORDER == BIG_ENDIAN
 291 #define le16_to_cpu(val) bswap_16(val)
 292 #define le32_to_cpu(val) bswap_32(val)
 293 #endif
 294
 295 static uint16_t elf16_to_cpu(uint16_t val)
 296 {
 297         return le16_to_cpu(val);
 298 }
 299
 300 static uint32_t elf32_to_cpu(uint32_t val)
 301 {
 302         return le32_to_cpu(val);
 303 }
 304
 305 #define elf_half_to_cpu(x)      elf16_to_cpu(x)
 306 #define elf_word_to_cpu(x)      elf32_to_cpu(x)
 307 #define elf_addr_to_cpu(x)      elf32_to_cpu(x)
 308 #define elf_off_to_cpu(x)       elf32_to_cpu(x)
 309 #define elf_xword_to_cpu(x)     elf32_to_cpu(x)
 310
 311 static void read_ehdr(FILE *fp)
 312 {
 313         if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
 314                 die("Cannot read ELF header: %s\n",
 315                         strerror(errno));
 316         }
 317         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
 318                 die("No ELF magic\n");
 319         }
 320         if (ehdr.e_ident[EI_CLASS] != ELF_CLASS) {
 321                 die("Not a %d bit executable\n", ELF_BITS);
 322         }
 323         if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
 324                 die("Not a LSB ELF executable\n");
 325         }
 326         if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
 327                 die("Unknown ELF version\n");
 328         }
 329         /* Convert the fields to native endian */
 330         ehdr.e_type      = elf_half_to_cpu(ehdr.e_type);
 331         ehdr.e_machine   = elf_half_to_cpu(ehdr.e_machine);
 332         ehdr.e_version   = elf_word_to_cpu(ehdr.e_version);
 333         ehdr.e_entry     = elf_addr_to_cpu(ehdr.e_entry);
 334         ehdr.e_phoff     = elf_off_to_cpu(ehdr.e_phoff);
 335         ehdr.e_shoff     = elf_off_to_cpu(ehdr.e_shoff);
 336         ehdr.e_flags     = elf_word_to_cpu(ehdr.e_flags);
 337         ehdr.e_ehsize    = elf_half_to_cpu(ehdr.e_ehsize);
 338         ehdr.e_phentsize = elf_half_to_cpu(ehdr.e_phentsize);
 339         ehdr.e_phnum     = elf_half_to_cpu(ehdr.e_phnum);
 340         ehdr.e_shentsize = elf_half_to_cpu(ehdr.e_shentsize);
 341         ehdr.e_shnum     = elf_half_to_cpu(ehdr.e_shnum);
 342         ehdr.e_shstrndx  = elf_half_to_cpu(ehdr.e_shstrndx);
 343
 344         if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
 345                 die("Unsupported ELF header type\n");
 346         }
 347         if (ehdr.e_machine != ELF_MACHINE) {
 348                 die("Not for %s\n", ELF_MACHINE_NAME);
 349         }
 350         if (ehdr.e_version != EV_CURRENT) {
 351                 die("Unknown ELF version\n");
 352         }
 353         if (ehdr.e_ehsize != sizeof(Elf_Ehdr)) {
 354                 die("Bad Elf header size\n");
 355         }
 356         if (ehdr.e_phentsize != sizeof(Elf_Phdr)) {
 357                 die("Bad program header entry\n");
 358         }
 359         if (ehdr.e_shentsize != sizeof(Elf_Shdr)) {
 360                 die("Bad section header entry\n");
 361         }
 362         if (ehdr.e_shstrndx >= ehdr.e_shnum) {
 363                 die("String table index out of bounds\n");
 364         }
 365 }
 366
 367 static void read_shdrs(FILE *fp)
 368 {
 369         int i;
 370         Elf_Shdr shdr;
 371
 372         secs = calloc(ehdr.e_shnum, sizeof(struct section));
 373         if (!secs) {
 374                 die("Unable to allocate %d section headers\n",
 375                     ehdr.e_shnum);
 376         }
 377         if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
 378                 die("Seek to %d failed: %s\n",
 379                         ehdr.e_shoff, strerror(errno));
 380         }
 381         for (i = 0; i < ehdr.e_shnum; i++) {
 382                 struct section *sec = &secs[i];
 383                 if (fread(&shdr, sizeof shdr, 1, fp) != 1)
 384                         die("Cannot read ELF section headers %d/%d: %s\n",
 385                             i, ehdr.e_shnum, strerror(errno));
 386                 sec->shdr.sh_name      = elf_word_to_cpu(shdr.sh_name);
 387                 sec->shdr.sh_type      = elf_word_to_cpu(shdr.sh_type);
 388                 sec->shdr.sh_flags     = elf_xword_to_cpu(shdr.sh_flags);
 389                 sec->shdr.sh_addr      = elf_addr_to_cpu(shdr.sh_addr);
 390                 sec->shdr.sh_offset    = elf_off_to_cpu(shdr.sh_offset);
 391                 sec->shdr.sh_size      = elf_xword_to_cpu(shdr.sh_size);
 392                 sec->shdr.sh_link      = elf_word_to_cpu(shdr.sh_link);
 393                 sec->shdr.sh_info      = elf_word_to_cpu(shdr.sh_info);
 394                 sec->shdr.sh_addralign = elf_xword_to_cpu(shdr.sh_addralign);
 395                 sec->shdr.sh_entsize   = elf_xword_to_cpu(shdr.sh_entsize);
 396                 if (sec->shdr.sh_link < ehdr.e_shnum)
 397                         sec->link = &secs[sec->shdr.sh_link];
 398         }
 399
 400 }
 401
 402 static void read_strtabs(FILE *fp)
 403 {
 404         int i;
 405         for (i = 0; i < ehdr.e_shnum; i++) {
 406                 struct section *sec = &secs[i];
 407                 if (sec->shdr.sh_type != SHT_STRTAB) {
 408                         continue;
 409                 }
 410                 sec->strtab = malloc(sec->shdr.sh_size);
 411                 if (!sec->strtab) {
 412                         die("malloc of %d bytes for strtab failed\n",
 413                                 sec->shdr.sh_size);
 414                 }
 415                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 416                         die("Seek to %d failed: %s\n",
 417                                 sec->shdr.sh_offset, strerror(errno));
 418                 }
 419                 if (fread(sec->strtab, 1, sec->shdr.sh_size, fp)
 420                     != sec->shdr.sh_size) {
 421                         die("Cannot read symbol table: %s\n",
 422                                 strerror(errno));
 423                 }
 424         }
 425 }
 426
 427 static void read_symtabs(FILE *fp)
 428 {
 429         int i,j;
 430         for (i = 0; i < ehdr.e_shnum; i++) {
 431                 struct section *sec = &secs[i];
 432                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 433                         continue;
 434                 }
 435                 sec->symtab = malloc(sec->shdr.sh_size);
 436                 if (!sec->symtab) {
 437                         die("malloc of %d bytes for symtab failed\n",
 438                                 sec->shdr.sh_size);
 439                 }
 440                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 441                         die("Seek to %d failed: %s\n",
 442                                 sec->shdr.sh_offset, strerror(errno));
 443                 }
 444                 if (fread(sec->symtab, 1, sec->shdr.sh_size, fp)
 445                     != sec->shdr.sh_size) {
 446                         die("Cannot read symbol table: %s\n",
 447                                 strerror(errno));
 448                 }
 449                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
 450                         Elf_Sym *sym = &sec->symtab[j];
 451                         sym->st_name  = elf_word_to_cpu(sym->st_name);
 452                         sym->st_value = elf_addr_to_cpu(sym->st_value);
 453                         sym->st_size  = elf_xword_to_cpu(sym->st_size);
 454                         sym->st_shndx = elf_half_to_cpu(sym->st_shndx);
 455                 }
 456         }
 457 }
 458
 459
 460 static void read_relocs(FILE *fp)
 461 {
 462         int i,j;
 463         for (i = 0; i < ehdr.e_shnum; i++) {
 464                 struct section *sec = &secs[i];
 465                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 466                         continue;
 467                 }
 468                 sec->reltab = malloc(sec->shdr.sh_size);
 469                 if (!sec->reltab) {
 470                         die("malloc of %d bytes for relocs failed\n",
 471                                 sec->shdr.sh_size);
 472                 }
 473                 if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) {
 474                         die("Seek to %d failed: %s\n",
 475                                 sec->shdr.sh_offset, strerror(errno));
 476                 }
 477                 if (fread(sec->reltab, 1, sec->shdr.sh_size, fp)
 478                     != sec->shdr.sh_size) {
 479                         die("Cannot read symbol table: %s\n",
 480                                 strerror(errno));
 481                 }
 482                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 483                         Elf_Rel *rel = &sec->reltab[j];
 484                         rel->r_offset = elf_addr_to_cpu(rel->r_offset);
 485                         rel->r_info   = elf_xword_to_cpu(rel->r_info);
 486                 }
 487         }
 488 }
 489
 490
 491 static void print_absolute_symbols(void)
 492 {
 493         int i;
 494         printf("Absolute symbols\n");
 495         printf(" Num:    Value Size  Type       Bind        Visibility  Name\n");
 496         for (i = 0; i < ehdr.e_shnum; i++) {
 497                 struct section *sec = &secs[i];
 498                 char *sym_strtab;
 499                 int j;
 500
 501                 if (sec->shdr.sh_type != SHT_SYMTAB) {
 502                         continue;
 503                 }
 504                 sym_strtab = sec->link->strtab;
 505                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) {
 506                         Elf_Sym *sym;
 507                         const char *name;
 508                         sym = &sec->symtab[j];
 509                         name = sym_name(sym_strtab, sym);
 510                         if (sym->st_shndx != SHN_ABS) {
 511                                 continue;
 512                         }
 513                         printf("%5d %08x %5d %10s %10s %12s %s\n",
 514                                 j, sym->st_value, sym->st_size,
 515                                 sym_type(ELF_ST_TYPE(sym->st_info)),
 516                                 sym_bind(ELF_ST_BIND(sym->st_info)),
 517                                 sym_visibility(ELF_ST_VISIBILITY(sym->st_other)),
 518                                 name);
 519                 }
 520         }
 521         printf("\n");
 522 }
 523
 524 static void print_absolute_relocs(void)
 525 {
 526         int i, printed = 0;
 527
 528         for (i = 0; i < ehdr.e_shnum; i++) {
 529                 struct section *sec = &secs[i];
 530                 struct section *sec_applies, *sec_symtab;
 531                 char *sym_strtab;
 532                 Elf_Sym *sh_symtab;
 533                 int j;
 534                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 535                         continue;
 536                 }
 537                 sec_symtab  = sec->link;
 538                 sec_applies = &secs[sec->shdr.sh_info];
 539                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 540                         continue;
 541                 }
 542                 sh_symtab  = sec_symtab->symtab;
 543                 sym_strtab = sec_symtab->link->strtab;
 544                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 545                         Elf_Rel *rel;
 546                         Elf_Sym *sym;
 547                         const char *name;
 548                         rel = &sec->reltab[j];
 549                         sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
 550                         name = sym_name(sym_strtab, sym);
 551                         if (sym->st_shndx != SHN_ABS) {
 552                                 continue;
 553                         }
 554
 555                         /* Absolute symbols are not relocated if bzImage is
 556                          * loaded at a non-compiled address. Display a warning
 557                          * to user at compile time about the absolute
 558                          * relocations present.
 559                          *
 560                          * User need to audit the code to make sure
 561                          * some symbols which should have been section
 562                          * relative have not become absolute because of some
 563                          * linker optimization or wrong programming usage.
 564                          *
 565                          * Before warning check if this absolute symbol
 566                          * relocation is harmless.
 567                          */
 568                         if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
 569                                 continue;
 570
 571                         if (!printed) {
 572                                 printf("WARNING: Absolute relocations"
 573                                         " present\n");
 574                                 printf("Offset     Info     Type     Sym.Value "
 575                                         "Sym.Name\n");
 576                                 printed = 1;
 577                         }
 578
 579                         printf("%08x %08x %10s %08x  %s\n",
 580                                 rel->r_offset,
 581                                 rel->r_info,
 582                                 rel_type(ELF_R_TYPE(rel->r_info)),
 583                                 sym->st_value,
 584                                 name);
 585                 }
 586         }
 587
 588         if (printed)
 589                 printf("\n");
 590 }
 591
 592 static void add_reloc(struct relocs *r, uint32_t offset)
 593 {
 594         if (r->count == r->size) {
 595                 unsigned long newsize = r->size + 50000;
 596                 void *mem = realloc(r->offset, newsize * sizeof(r->offset[0]));
 597
 598                 if (!mem)
 599                         die("realloc of %ld entries for relocs failed\n",
 600                                 newsize);
 601                 r->offset = mem;
 602                 r->size = newsize;
 603         }
 604         r->offset[r->count++] = offset;
 605 }
 606
 607 static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel,
 608                         Elf_Sym *sym, const char *symname))
 609 {
 610         int i;
 611         /* Walk through the relocations */
 612         for (i = 0; i < ehdr.e_shnum; i++) {
 613                 char *sym_strtab;
 614                 Elf_Sym *sh_symtab;
 615                 struct section *sec_applies, *sec_symtab;
 616                 int j;
 617                 struct section *sec = &secs[i];
 618
 619                 if (sec->shdr.sh_type != SHT_REL_TYPE) {
 620                         continue;
 621                 }
 622                 sec_symtab  = sec->link;
 623                 sec_applies = &secs[sec->shdr.sh_info];
 624                 if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) {
 625                         continue;
 626                 }
 627                 sh_symtab = sec_symtab->symtab;
 628                 sym_strtab = sec_symtab->link->strtab;
 629                 for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
 630                         Elf_Rel *rel = &sec->reltab[j];
 631                         Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
 632                         const char *symname = sym_name(sym_strtab, sym);
 633
 634                         process(sec, rel, sym, symname);
 635                 }
 636         }
 637 }
 638
 639 static int do_reloc(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 640                     const char *symname)
 641 {
 642         unsigned r_type = ELF32_R_TYPE(rel->r_info);
 643         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 644
 645         switch (r_type) {
 646         case R_386_NONE:
 647         case R_386_PC32:
 648         case R_386_PC16:
 649         case R_386_PC8:
 650                 /*
 651                  * NONE can be ignored and PC relative relocations don't
 652                  * need to be adjusted.
 653                  */
 654                 break;
 655
 656         case R_386_32:
 657                 if (shn_abs) {
 658                         /*
 659                          * Whitelisted absolute symbols do not require
 660                          * relocation.
 661                          */
 662                         if (is_reloc(S_ABS, symname))
 663                                 break;
 664
 665                         die("Invalid absolute %s relocation: %s\n",
 666                             rel_type(r_type), symname);
 667                         break;
 668                 }
 669
 670                 add_reloc(&relocs32, rel->r_offset);
 671                 break;
 672
 673         default:
 674                 die("Unsupported relocation type: %s (%d)\n",
 675                     rel_type(r_type), r_type);
 676                 break;
 677         }
 678
 679         return 0;
 680 }
 681
 682 static int do_reloc_real(struct section *sec, Elf_Rel *rel, Elf_Sym *sym,
 683                          const char *symname)
 684 {
 685         unsigned r_type = ELF32_R_TYPE(rel->r_info);
 686         int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname);
 687
 688         switch (r_type) {
 689         case R_386_NONE:
 690         case R_386_PC32:
 691         case R_386_PC16:
 692         case R_386_PC8:
 693                 /*
 694                  * NONE can be ignored and PC relative relocations don't
 695                  * need to be adjusted.
 696                  */
 697                 break;
 698
 699         case R_386_16:
 700                 if (shn_abs) {
 701                         /*
 702                          * Whitelisted absolute symbols do not require
 703                          * relocation.
 704                          */
 705                         if (is_reloc(S_ABS, symname))
 706                                 break;
 707
 708                         if (is_reloc(S_SEG, symname)) {
 709                                 add_reloc(&relocs16, rel->r_offset);
 710                                 break;
 711                         }
 712                 } else {
 713                         if (!is_reloc(S_LIN, symname))
 714                                 break;
 715                 }
 716                 die("Invalid %s %s relocation: %s\n",
 717                     shn_abs ? "absolute" : "relative",
 718                     rel_type(r_type), symname);
 719                 break;
 720
 721         case R_386_32:
 722                 if (shn_abs) {
 723                         /*
 724                          * Whitelisted absolute symbols do not require
 725                          * relocation.
 726                          */
 727                         if (is_reloc(S_ABS, symname))
 728                                 break;
 729
 730                         if (is_reloc(S_REL, symname)) {
 731                                 add_reloc(&relocs32, rel->r_offset);
 732                                 break;
 733                         }
 734                 } else {
 735                         if (is_reloc(S_LIN, symname))
 736                                 add_reloc(&relocs32, rel->r_offset);
 737                         break;
 738                 }
 739                 die("Invalid %s %s relocation: %s\n",
 740                     shn_abs ? "absolute" : "relative",
 741                     rel_type(r_type), symname);
 742                 break;
 743
 744         default:
 745                 die("Unsupported relocation type: %s (%d)\n",
 746                     rel_type(r_type), r_type);
 747                 break;
 748         }
 749
 750         return 0;
 751 }
 752
 753 static int cmp_relocs(const void *va, const void *vb)
 754 {
 755         const uint32_t *a, *b;
 756         a = va; b = vb;
 757         return (*a == *b)? 0 : (*a > *b)? 1 : -1;
 758 }
 759
 760 static void sort_relocs(struct relocs *r)
 761 {
 762         qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs);
 763 }
 764
 765 static int write32(uint32_t v, FILE *f)
 766 {
 767         unsigned char buf[4];
 768
 769         put_unaligned_le32(v, buf);
 770         return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
 771 }
 772
 773 static int write32_as_text(uint32_t v, FILE *f)
 774 {
 775         return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1;
 776 }
 777
 778 static void emit_relocs(int as_text, int use_real_mode)
 779 {
 780         int i;
 781         int (*write_reloc)(uint32_t, FILE *) = write32;
 782
 783         /* Collect up the relocations */
 784         walk_relocs(use_real_mode ? do_reloc_real : do_reloc);
 785
 786         if (relocs16.count && !use_real_mode)
 787                 die("Segment relocations found but --realmode not specified\n");
 788
 789         /* Order the relocations for more efficient processing */
 790         sort_relocs(&relocs16);
 791         sort_relocs(&relocs32);
 792
 793         /* Print the relocations */
 794         if (as_text) {
 795                 /* Print the relocations in a form suitable that
 796                  * gas will like.
 797                  */
 798                 printf(".section \".data.reloc\",\"a\"\n");
 799                 printf(".balign 4\n");
 800                 write_reloc = write32_as_text;
 801         }
 802
 803         if (use_real_mode) {
 804                 write_reloc(relocs16.count, stdout);
 805                 for (i = 0; i < relocs16.count; i++)
 806                         write_reloc(relocs16.offset[i], stdout);
 807
 808                 write_reloc(relocs32.count, stdout);
 809                 for (i = 0; i < relocs32.count; i++)
 810                         write_reloc(relocs32.offset[i], stdout);
 811         } else {
 812                 /* Print a stop */
 813                 write_reloc(0, stdout);
 814
 815                 /* Now print each relocation */
 816                 for (i = 0; i < relocs32.count; i++)
 817                         write_reloc(relocs32.offset[i], stdout);
 818         }
 819 }
 820
 821 static void usage(void)
 822 {
 823         die("relocs [--abs-syms|--abs-relocs|--text|--realmode] vmlinux\n");
 824 }
 825
 826 int main(int argc, char **argv)
 827 {
 828         int show_absolute_syms, show_absolute_relocs;
 829         int as_text, use_real_mode;
 830         const char *fname;
 831         FILE *fp;
 832         int i;
 833
 834         show_absolute_syms = 0;
 835         show_absolute_relocs = 0;
 836         as_text = 0;
 837         use_real_mode = 0;
 838         fname = NULL;
 839         for (i = 1; i < argc; i++) {
 840                 char *arg = argv[i];
 841                 if (*arg == '-') {
 842                         if (strcmp(arg, "--abs-syms") == 0) {
 843                                 show_absolute_syms = 1;
 844                                 continue;
 845                         }
 846                         if (strcmp(arg, "--abs-relocs") == 0) {
 847                                 show_absolute_relocs = 1;
 848                                 continue;
 849                         }
 850                         if (strcmp(arg, "--text") == 0) {
 851                                 as_text = 1;
 852                                 continue;
 853                         }
 854                         if (strcmp(arg, "--realmode") == 0) {
 855                                 use_real_mode = 1;
 856                                 continue;
 857                         }
 858                 }
 859                 else if (!fname) {
 860                         fname = arg;
 861                         continue;
 862                 }
 863                 usage();
 864         }
 865         if (!fname) {
 866                 usage();
 867         }
 868         regex_init(use_real_mode);
 869         fp = fopen(fname, "r");
 870         if (!fp) {
 871                 die("Cannot open %s: %s\n",
 872                         fname, strerror(errno));
 873         }
 874         read_ehdr(fp);
 875         read_shdrs(fp);
 876         read_strtabs(fp);
 877         read_symtabs(fp);
 878         read_relocs(fp);
 879         if (show_absolute_syms) {
 880                 print_absolute_symbols();
 881                 goto out;
 882         }
 883         if (show_absolute_relocs) {
 884                 print_absolute_relocs();
 885                 goto out;
 886         }
 887         emit_relocs(as_text, use_real_mode);
 888 out:
 889         fclose(fp);
 890         return 0;
 891 }