x86_64-link.c

   1 #ifdef TARGET_DEFS_ONLY
   2
   3 #define EM_TCC_TARGET EM_X86_64
   4
   5 /* relocation type for 32 bit data relocation */
   6 #define R_DATA_32   R_X86_64_32S
   7 #define R_DATA_PTR  R_X86_64_64
   8 #define R_JMP_SLOT  R_X86_64_JUMP_SLOT
   9 #define R_GLOB_DAT  R_X86_64_GLOB_DAT
  10 #define R_COPY      R_X86_64_COPY
  11 #define R_RELATIVE  R_X86_64_RELATIVE
  12
  13 #define R_NUM       R_X86_64_NUM
  14
  15 #define ELF_START_ADDR 0x400000
  16 #define ELF_PAGE_SIZE  0x200000
  17
  18 #define PCRELATIVE_DLLPLT 1
  19 #define RELOCATE_DLLPLT 1
  20
  21 #else /* !TARGET_DEFS_ONLY */
  22
  23 #include "tcc.h"
  24
  25 #ifdef NEED_RELOC_TYPE
  26 /* Returns 1 for a code relocation, 0 for a data relocation. For unknown
  27    relocations, returns -1. */
  28 int code_reloc (int reloc_type)
  29 {
  30     switch (reloc_type) {
  31         case R_X86_64_32:
  32         case R_X86_64_32S:
  33         case R_X86_64_64:
  34         case R_X86_64_GOTPC32:
  35         case R_X86_64_GOTPC64:
  36         case R_X86_64_GOTPCREL:
  37         case R_X86_64_GOTPCRELX:
  38         case R_X86_64_REX_GOTPCRELX:
  39         case R_X86_64_GOTTPOFF:
  40         case R_X86_64_GOT32:
  41         case R_X86_64_GOT64:
  42         case R_X86_64_GLOB_DAT:
  43         case R_X86_64_COPY:
  44         case R_X86_64_RELATIVE:
  45         case R_X86_64_GOTOFF64:
  46         case R_X86_64_TLSGD:
  47         case R_X86_64_TLSLD:
  48         case R_X86_64_DTPOFF32:
  49         case R_X86_64_TPOFF32:
  50         case R_X86_64_DTPOFF64:
  51         case R_X86_64_TPOFF64:
  52             return 0;
  53
  54         case R_X86_64_PC32:
  55         case R_X86_64_PC64:
  56         case R_X86_64_PLT32:
  57         case R_X86_64_PLTOFF64:
  58         case R_X86_64_JUMP_SLOT:
  59             return 1;
  60     }
  61     return -1;
  62 }
  63
  64 /* Returns an enumerator to describe whether and when the relocation needs a
  65    GOT and/or PLT entry to be created. See tcc.h for a description of the
  66    different values. */
  67 int gotplt_entry_type (int reloc_type)
  68 {
  69     switch (reloc_type) {
  70         case R_X86_64_GLOB_DAT:
  71         case R_X86_64_JUMP_SLOT:
  72         case R_X86_64_COPY:
  73         case R_X86_64_RELATIVE:
  74             return NO_GOTPLT_ENTRY;
  75
  76         /* The following relocs wouldn't normally need GOT or PLT
  77            slots, but we need them for simplicity in the link
  78            editor part.  See our caller for comments.  */
  79         case R_X86_64_32:
  80         case R_X86_64_32S:
  81         case R_X86_64_64:
  82         case R_X86_64_PC32:
  83         case R_X86_64_PC64:
  84             return AUTO_GOTPLT_ENTRY;
  85
  86         case R_X86_64_GOTTPOFF:
  87             return BUILD_GOT_ONLY;
  88
  89         case R_X86_64_GOT32:
  90         case R_X86_64_GOT64:
  91         case R_X86_64_GOTPC32:
  92         case R_X86_64_GOTPC64:
  93         case R_X86_64_GOTOFF64:
  94         case R_X86_64_GOTPCREL:
  95         case R_X86_64_GOTPCRELX:
  96         case R_X86_64_TLSGD:
  97         case R_X86_64_TLSLD:
  98         case R_X86_64_DTPOFF32:
  99         case R_X86_64_TPOFF32:
 100         case R_X86_64_DTPOFF64:
 101         case R_X86_64_TPOFF64:
 102         case R_X86_64_REX_GOTPCRELX:
 103         case R_X86_64_PLT32:
 104         case R_X86_64_PLTOFF64:
 105             return ALWAYS_GOTPLT_ENTRY;
 106     }
 107
 108     return -1;
 109 }
 110
 111 #ifdef NEED_BUILD_GOT
 112 ST_FUNC unsigned create_plt_entry(TCCState *s1, unsigned got_offset, struct sym_attr *attr)
 113 {
 114     Section *plt = s1->plt;
 115     uint8_t *p;
 116     int modrm;
 117     unsigned plt_offset, relofs;
 118
 119     modrm = 0x25;
 120
 121     /* empty PLT: create PLT0 entry that pushes the library identifier
 122        (GOT + PTR_SIZE) and jumps to ld.so resolution routine
 123        (GOT + 2 * PTR_SIZE) */
 124     if (plt->data_offset == 0) {
 125         p = section_ptr_add(plt, 16);
 126         p[0] = 0xff; /* pushl got + PTR_SIZE */
 127         p[1] = modrm + 0x10;
 128         write32le(p + 2, PTR_SIZE);
 129         p[6] = 0xff; /* jmp *(got + PTR_SIZE * 2) */
 130         p[7] = modrm;
 131         write32le(p + 8, PTR_SIZE * 2);
 132     }
 133     plt_offset = plt->data_offset;
 134
 135     /* The PLT slot refers to the relocation entry it needs via offset.
 136        The reloc entry is created below, so its offset is the current
 137        data_offset */
 138     relofs = s1->plt->reloc ? s1->plt->reloc->data_offset : 0;
 139
 140     /* Jump to GOT entry where ld.so initially put the address of ip + 4 */
 141     p = section_ptr_add(plt, 16);
 142     p[0] = 0xff; /* jmp *(got + x) */
 143     p[1] = modrm;
 144     write32le(p + 2, got_offset);
 145     p[6] = 0x68; /* push $xxx */
 146     /* On x86-64, the relocation is referred to by _index_ */
 147     write32le(p + 7, relofs / sizeof (ElfW_Rel) - 1);
 148     p[11] = 0xe9; /* jmp plt_start */
 149     write32le(p + 12, -(plt->data_offset));
 150     return plt_offset;
 151 }
 152
 153 /* relocate the PLT: compute addresses and offsets in the PLT now that final
 154    address for PLT and GOT are known (see fill_program_header) */
 155 ST_FUNC void relocate_plt(TCCState *s1)
 156 {
 157     uint8_t *p, *p_end;
 158
 159     if (!s1->plt)
 160       return;
 161
 162     p = s1->plt->data;
 163     p_end = p + s1->plt->data_offset;
 164
 165     if (p < p_end) {
 166         int x = s1->got->sh_addr - s1->plt->sh_addr - 6;
 167         add32le(p + 2, x);
 168         add32le(p + 8, x - 6);
 169         p += 16;
 170         while (p < p_end) {
 171             add32le(p + 2, x + (s1->plt->data - p));
 172             p += 16;
 173         }
 174     }
 175
 176     if (s1->plt->reloc) {
 177         ElfW_Rel *rel;
 178         int x = s1->plt->sh_addr + 16 + 6;
 179         p = s1->got->data;
 180         for_each_elem(s1->plt->reloc, 0, rel, ElfW_Rel) {
 181             write64le(p + rel->r_offset, x);
 182             x += 16;
 183         }
 184     }
 185 }
 186 #endif
 187 #endif
 188
 189 void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr, addr_t addr, addr_t val)
 190 {
 191     int sym_index, esym_index;
 192
 193     sym_index = ELFW(R_SYM)(rel->r_info);
 194
 195     switch (type) {
 196         case R_X86_64_64:
 197             if (s1->output_type & TCC_OUTPUT_DYN) {
 198                 esym_index = get_sym_attr(s1, sym_index, 0)->dyn_index;
 199                 qrel->r_offset = rel->r_offset;
 200                 if (esym_index) {
 201                     qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_64);
 202                     qrel->r_addend = rel->r_addend;
 203                     qrel++;
 204                     break;
 205                 } else {
 206                     qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE);
 207                     qrel->r_addend = read64le(ptr) + val;
 208                     qrel++;
 209                 }
 210             }
 211             add64le(ptr, val);
 212             break;
 213         case R_X86_64_32:
 214         case R_X86_64_32S:
 215             if (s1->output_type & TCC_OUTPUT_DYN) {
 216                 /* XXX: this logic may depend on TCC's codegen
 217                    now TCC uses R_X86_64_32 even for a 64bit pointer */
 218                 qrel->r_offset = rel->r_offset;
 219                 qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE);
 220                 /* Use sign extension! */
 221                 qrel->r_addend = (int)read32le(ptr) + val;
 222                 qrel++;
 223             }
 224             add32le(ptr, val);
 225             break;
 226
 227         case R_X86_64_PC32:
 228             if (s1->output_type == TCC_OUTPUT_DLL) {
 229                 /* DLL relocation */
 230                 esym_index = get_sym_attr(s1, sym_index, 0)->dyn_index;
 231                 if (esym_index) {
 232                     qrel->r_offset = rel->r_offset;
 233                     qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_PC32);
 234                     /* Use sign extension! */
 235                     qrel->r_addend = (int)read32le(ptr) + rel->r_addend;
 236                     qrel++;
 237                     break;
 238                 }
 239             }
 240             goto plt32pc32;
 241
 242         case R_X86_64_PLT32:
 243             /* fallthrough: val already holds the PLT slot address */
 244
 245         plt32pc32:
 246         {
 247             long long diff;
 248             diff = (long long)val - addr;
 249             if (diff < -2147483648LL || diff > 2147483647LL) {
 250 #ifdef TCC_TARGET_PE
 251               /* ignore overflow with undefined weak symbols */
 252               if (((ElfW(Sym)*)symtab_section->data)[sym_index].st_shndx != SHN_UNDEF)
 253 #endif
 254                 tcc_error_noabort("internal error: relocation failed");
 255             }
 256             add32le(ptr, diff);
 257         }
 258             break;
 259
 260         case R_X86_64_COPY:
 261             break;
 262
 263         case R_X86_64_PLTOFF64:
 264             add64le(ptr, val - s1->got->sh_addr + rel->r_addend);
 265             break;
 266
 267         case R_X86_64_PC64:
 268             if (s1->output_type == TCC_OUTPUT_DLL) {
 269                 /* DLL relocation */
 270                 esym_index = get_sym_attr(s1, sym_index, 0)->dyn_index;
 271                 if (esym_index) {
 272                     qrel->r_offset = rel->r_offset;
 273                     qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_PC64);
 274                     qrel->r_addend = read64le(ptr) + rel->r_addend;
 275                     qrel++;
 276                     break;
 277                 }
 278             }
 279             add64le(ptr, val - addr);
 280             break;
 281
 282         case R_X86_64_GLOB_DAT:
 283         case R_X86_64_JUMP_SLOT:
 284             /* They don't need addend */
 285             write64le(ptr, val - rel->r_addend);
 286             break;
 287         case R_X86_64_GOTPCREL:
 288         case R_X86_64_GOTPCRELX:
 289         case R_X86_64_REX_GOTPCRELX:
 290             add32le(ptr, s1->got->sh_addr - addr +
 291                          get_sym_attr(s1, sym_index, 0)->got_offset - 4);
 292             break;
 293         case R_X86_64_GOTPC32:
 294             add32le(ptr, s1->got->sh_addr - addr + rel->r_addend);
 295             break;
 296         case R_X86_64_GOTPC64:
 297             add64le(ptr, s1->got->sh_addr - addr + rel->r_addend);
 298             break;
 299         case R_X86_64_GOTTPOFF:
 300             add32le(ptr, val - s1->got->sh_addr);
 301             break;
 302         case R_X86_64_GOT32:
 303             /* we load the got offset */
 304             add32le(ptr, get_sym_attr(s1, sym_index, 0)->got_offset);
 305             break;
 306         case R_X86_64_GOT64:
 307             /* we load the got offset */
 308             add64le(ptr, get_sym_attr(s1, sym_index, 0)->got_offset);
 309             break;
 310         case R_X86_64_GOTOFF64:
 311             add64le(ptr, val - s1->got->sh_addr);
 312             break;
 313         case R_X86_64_TLSGD:
 314             {
 315                 static const unsigned char expect[] = {
 316                     /* .byte 0x66; lea 0(%rip),%rdi */
 317                     0x66, 0x48, 0x8d, 0x3d, 0x00, 0x00, 0x00, 0x00,
 318                     /* .word 0x6666; rex64; call __tls_get_addr@PLT */
 319                     0x66, 0x66, 0x48, 0xe8, 0x00, 0x00, 0x00, 0x00 };
 320                 static const unsigned char replace[] = {
 321                     /* mov %fs:0,%rax */
 322                     0x64, 0x48, 0x8b, 0x04, 0x25, 0x00, 0x00, 0x00, 0x00,
 323                     /* lea -4(%rax),%rax */
 324                     0x48, 0x8d, 0x80, 0x00, 0x00, 0x00, 0x00 };
 325
 326                 if (memcmp (ptr-4, expect, sizeof(expect)) == 0) {
 327                     ElfW(Sym) *sym;
 328                     Section *sec;
 329                     int32_t x;
 330
 331                     memcpy(ptr-4, replace, sizeof(replace));
 332                     rel[1].r_info = ELFW(R_INFO)(0, R_X86_64_NONE);
 333                     sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
 334                     sec = s1->sections[sym->st_shndx];
 335                     x = sym->st_value - sec->sh_addr - sec->data_offset;
 336                     add32le(ptr + 8, x);
 337                 }
 338                 else
 339                     tcc_error_noabort("unexpected R_X86_64_TLSGD pattern");
 340             }
 341             break;
 342         case R_X86_64_TLSLD:
 343             {
 344                 static const unsigned char expect[] = {
 345                     /* lea 0(%rip),%rdi */
 346                     0x48, 0x8d, 0x3d, 0x00, 0x00, 0x00, 0x00,
 347                     /* call __tls_get_addr@PLT */
 348                     0xe8, 0x00, 0x00, 0x00, 0x00 };
 349                 static const unsigned char replace[] = {
 350                     /* data16 data16 data16 mov %fs:0,%rax */
 351                     0x66, 0x66, 0x66, 0x64, 0x48, 0x8b, 0x04, 0x25,
 352                     0x00, 0x00, 0x00, 0x00 };
 353
 354                 if (memcmp (ptr-3, expect, sizeof(expect)) == 0) {
 355                     memcpy(ptr-3, replace, sizeof(replace));
 356                     rel[1].r_info = ELFW(R_INFO)(0, R_X86_64_NONE);
 357                 }
 358                 else
 359                     tcc_error_noabort("unexpected R_X86_64_TLSLD pattern");
 360             }
 361             break;
 362         case R_X86_64_DTPOFF32:
 363         case R_X86_64_TPOFF32:
 364             {
 365                 ElfW(Sym) *sym;
 366                 Section *sec;
 367                 int32_t x;
 368
 369                 sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
 370                 sec = s1->sections[sym->st_shndx];
 371                 x = val - sec->sh_addr - sec->data_offset;
 372                 add32le(ptr, x);
 373             }
 374             break;
 375         case R_X86_64_DTPOFF64:
 376         case R_X86_64_TPOFF64:
 377             {
 378                 ElfW(Sym) *sym;
 379                 Section *sec;
 380                 int32_t x;
 381
 382                 sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
 383                 sec = s1->sections[sym->st_shndx];
 384                 x = val - sec->sh_addr - sec->data_offset;
 385                 add64le(ptr, x);
 386             }
 387             break;
 388         case R_X86_64_NONE:
 389             break;
 390         case R_X86_64_RELATIVE:
 391 #ifdef TCC_TARGET_PE
 392             add32le(ptr, val - s1->pe_imagebase);
 393 #endif
 394             /* do nothing */
 395             break;
 396         default:
 397             fprintf(stderr,"FIXME: handle reloc type %d at %x [%p] to %x\n",
 398                 type, (unsigned)addr, ptr, (unsigned)val);
 399             break;
 400     }
 401 }
 402
 403 #endif /* !TARGET_DEFS_ONLY */