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