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             return 0;
  47
  48         case R_X86_64_PC32:
  49         case R_X86_64_PC64:
  50         case R_X86_64_PLT32:
  51         case R_X86_64_PLTOFF64:
  52         case R_X86_64_JUMP_SLOT:
  53             return 1;
  54     }
  55     return -1;
  56 }
  57
  58 /* Returns an enumerator to describe whether and when the relocation needs a
  59    GOT and/or PLT entry to be created. See tcc.h for a description of the
  60    different values. */
  61 int gotplt_entry_type (int reloc_type)
  62 {
  63     switch (reloc_type) {
  64         case R_X86_64_GLOB_DAT:
  65         case R_X86_64_JUMP_SLOT:
  66         case R_X86_64_COPY:
  67         case R_X86_64_RELATIVE:
  68             return NO_GOTPLT_ENTRY;
  69
  70         /* The following relocs wouldn't normally need GOT or PLT
  71            slots, but we need them for simplicity in the link
  72            editor part.  See our caller for comments.  */
  73         case R_X86_64_32:
  74         case R_X86_64_32S:
  75         case R_X86_64_64:
  76         case R_X86_64_PC32:
  77         case R_X86_64_PC64:
  78             return AUTO_GOTPLT_ENTRY;
  79
  80         case R_X86_64_GOTTPOFF:
  81             return BUILD_GOT_ONLY;
  82
  83         case R_X86_64_GOT32:
  84         case R_X86_64_GOT64:
  85         case R_X86_64_GOTPC32:
  86         case R_X86_64_GOTPC64:
  87         case R_X86_64_GOTOFF64:
  88         case R_X86_64_GOTPCREL:
  89         case R_X86_64_GOTPCRELX:
  90         case R_X86_64_REX_GOTPCRELX:
  91         case R_X86_64_PLT32:
  92         case R_X86_64_PLTOFF64:
  93             return ALWAYS_GOTPLT_ENTRY;
  94     }
  95
  96     return -1;
  97 }
  98
  99 ST_FUNC unsigned create_plt_entry(TCCState *s1, unsigned got_offset, struct sym_attr *attr)
 100 {
 101     Section *plt = s1->plt;
 102     uint8_t *p;
 103     int modrm;
 104     unsigned plt_offset, relofs;
 105
 106     modrm = 0x25;
 107
 108     /* empty PLT: create PLT0 entry that pushes the library identifier
 109        (GOT + PTR_SIZE) and jumps to ld.so resolution routine
 110        (GOT + 2 * PTR_SIZE) */
 111     if (plt->data_offset == 0) {
 112         p = section_ptr_add(plt, 16);
 113         p[0] = 0xff; /* pushl got + PTR_SIZE */
 114         p[1] = modrm + 0x10;
 115         write32le(p + 2, PTR_SIZE);
 116         p[6] = 0xff; /* jmp *(got + PTR_SIZE * 2) */
 117         p[7] = modrm;
 118         write32le(p + 8, PTR_SIZE * 2);
 119     }
 120     plt_offset = plt->data_offset;
 121
 122     /* The PLT slot refers to the relocation entry it needs via offset.
 123        The reloc entry is created below, so its offset is the current
 124        data_offset */
 125     relofs = s1->got->reloc ? s1->got->reloc->data_offset : 0;
 126
 127     /* Jump to GOT entry where ld.so initially put the address of ip + 4 */
 128     p = section_ptr_add(plt, 16);
 129     p[0] = 0xff; /* jmp *(got + x) */
 130     p[1] = modrm;
 131     write32le(p + 2, got_offset);
 132     p[6] = 0x68; /* push $xxx */
 133     /* On x86-64, the relocation is referred to by _index_ */
 134     write32le(p + 7, relofs / sizeof (ElfW_Rel));
 135     p[11] = 0xe9; /* jmp plt_start */
 136     write32le(p + 12, -(plt->data_offset));
 137     return plt_offset;
 138 }
 139
 140 /* relocate the PLT: compute addresses and offsets in the PLT now that final
 141    address for PLT and GOT are known (see fill_program_header) */
 142 ST_FUNC void relocate_plt(TCCState *s1)
 143 {
 144     uint8_t *p, *p_end;
 145
 146     if (!s1->plt)
 147       return;
 148
 149     p = s1->plt->data;
 150     p_end = p + s1->plt->data_offset;
 151
 152     if (p < p_end) {
 153         int x = s1->got->sh_addr - s1->plt->sh_addr - 6;
 154         add32le(p + 2, x);
 155         add32le(p + 8, x - 6);
 156         p += 16;
 157         while (p < p_end) {
 158             add32le(p + 2, x + (s1->plt->data - p));
 159             p += 16;
 160         }
 161     }
 162 }
 163 #endif
 164
 165 void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr, addr_t addr, addr_t val)
 166 {
 167     int sym_index, esym_index;
 168
 169     sym_index = ELFW(R_SYM)(rel->r_info);
 170
 171     switch (type) {
 172         case R_X86_64_64:
 173             if (s1->output_type == TCC_OUTPUT_DLL) {
 174                 esym_index = get_sym_attr(s1, sym_index, 0)->dyn_index;
 175                 qrel->r_offset = rel->r_offset;
 176                 if (esym_index) {
 177                     qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_64);
 178                     qrel->r_addend = rel->r_addend;
 179                     qrel++;
 180                     break;
 181                 } else {
 182                     qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE);
 183                     qrel->r_addend = read64le(ptr) + val;
 184                     qrel++;
 185                 }
 186             }
 187             add64le(ptr, val);
 188             break;
 189         case R_X86_64_32:
 190         case R_X86_64_32S:
 191             if (s1->output_type == TCC_OUTPUT_DLL) {
 192                 /* XXX: this logic may depend on TCC's codegen
 193                    now TCC uses R_X86_64_32 even for a 64bit pointer */
 194                 qrel->r_offset = rel->r_offset;
 195                 qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE);
 196                 /* Use sign extension! */
 197                 qrel->r_addend = (int)read32le(ptr) + val;
 198                 qrel++;
 199             }
 200             add32le(ptr, val);
 201             break;
 202
 203         case R_X86_64_PC32:
 204             if (s1->output_type == TCC_OUTPUT_DLL) {
 205                 /* DLL relocation */
 206                 esym_index = get_sym_attr(s1, sym_index, 0)->dyn_index;
 207                 if (esym_index) {
 208                     qrel->r_offset = rel->r_offset;
 209                     qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_PC32);
 210                     /* Use sign extension! */
 211                     qrel->r_addend = (int)read32le(ptr) + rel->r_addend;
 212                     qrel++;
 213                     break;
 214                 }
 215             }
 216             goto plt32pc32;
 217
 218         case R_X86_64_PLT32:
 219             /* fallthrough: val already holds the PLT slot address */
 220
 221         plt32pc32:
 222         {
 223             long long diff;
 224             diff = (long long)val - addr;
 225             if (diff < -2147483648LL || diff > 2147483647LL) {
 226                 tcc_error("internal error: relocation failed");
 227             }
 228             add32le(ptr, diff);
 229         }
 230             break;
 231
 232         case R_X86_64_PLTOFF64:
 233             add64le(ptr, val - s1->got->sh_addr + rel->r_addend);
 234             break;
 235
 236         case R_X86_64_PC64:
 237             if (s1->output_type == TCC_OUTPUT_DLL) {
 238                 /* DLL relocation */
 239                 esym_index = get_sym_attr(s1, sym_index, 0)->dyn_index;
 240                 if (esym_index) {
 241                     qrel->r_offset = rel->r_offset;
 242                     qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_PC64);
 243                     qrel->r_addend = read64le(ptr) + rel->r_addend;
 244                     qrel++;
 245                     break;
 246                 }
 247             }
 248             add64le(ptr, val - addr);
 249             break;
 250
 251         case R_X86_64_GLOB_DAT:
 252         case R_X86_64_JUMP_SLOT:
 253             /* They don't need addend */
 254             write64le(ptr, val - rel->r_addend);
 255             break;
 256         case R_X86_64_GOTPCREL:
 257         case R_X86_64_GOTPCRELX:
 258         case R_X86_64_REX_GOTPCRELX:
 259             add32le(ptr, s1->got->sh_addr - addr +
 260                          get_sym_attr(s1, sym_index, 0)->got_offset - 4);
 261             break;
 262         case R_X86_64_GOTPC32:
 263             add32le(ptr, s1->got->sh_addr - addr + rel->r_addend);
 264             break;
 265         case R_X86_64_GOTPC64:
 266             add64le(ptr, s1->got->sh_addr - addr + rel->r_addend);
 267             break;
 268         case R_X86_64_GOTTPOFF:
 269             add32le(ptr, val - s1->got->sh_addr);
 270             break;
 271         case R_X86_64_GOT32:
 272             /* we load the got offset */
 273             add32le(ptr, get_sym_attr(s1, sym_index, 0)->got_offset);
 274             break;
 275         case R_X86_64_GOT64:
 276             /* we load the got offset */
 277             add64le(ptr, get_sym_attr(s1, sym_index, 0)->got_offset);
 278             break;
 279         case R_X86_64_GOTOFF64:
 280             add64le(ptr, val - s1->got->sh_addr);
 281             break;
 282         case R_X86_64_RELATIVE:
 283 #ifdef TCC_TARGET_PE
 284             add32le(ptr, val - s1->pe_imagebase);
 285 #endif
 286             /* do nothing */
 287             break;
 288     }
 289 }
 290
 291 #endif /* !TARGET_DEFS_ONLY */