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 /* Returns 1 for a code relocation, 0 for a data relocation. For unknown
  26    relocations, returns -1. */
  27 int code_reloc (int reloc_type)
  28 {
  29     switch (reloc_type) {
  30         case R_X86_64_32:
  31         case R_X86_64_32S:
  32         case R_X86_64_64:
  33         case R_X86_64_GOTPC32:
  34         case R_X86_64_GOTPC64:
  35         case R_X86_64_GOTPCREL:
  36         case R_X86_64_GOTPCRELX:
  37         case R_X86_64_REX_GOTPCRELX:
  38         case R_X86_64_GOTTPOFF:
  39         case R_X86_64_GOT32:
  40         case R_X86_64_GOT64:
  41         case R_X86_64_GLOB_DAT:
  42         case R_X86_64_COPY:
  43         case R_X86_64_RELATIVE:
  44         case R_X86_64_GOTOFF64:
  45             return 0;
  46
  47         case R_X86_64_PC32:
  48         case R_X86_64_PC64:
  49         case R_X86_64_PLT32:
  50         case R_X86_64_PLTOFF64:
  51         case R_X86_64_JUMP_SLOT:
  52             return 1;
  53     }
  54
  55     tcc_error ("Unknown relocation type: %d", reloc_type);
  56     return -1;
  57 }
  58
  59 /* Returns an enumerator to describe whether and when the relocation needs a
  60    GOT and/or PLT entry to be created. See tcc.h for a description of the
  61    different values. */
  62 int gotplt_entry_type (int reloc_type)
  63 {
  64     switch (reloc_type) {
  65         case R_X86_64_GLOB_DAT:
  66         case R_X86_64_JUMP_SLOT:
  67         case R_X86_64_COPY:
  68         case R_X86_64_RELATIVE:
  69             return NO_GOTPLT_ENTRY;
  70
  71         /* The following relocs wouldn't normally need GOT or PLT
  72            slots, but we need them for simplicity in the link
  73            editor part.  See our caller for comments.  */
  74         case R_X86_64_32:
  75         case R_X86_64_32S:
  76         case R_X86_64_64:
  77         case R_X86_64_PC32:
  78         case R_X86_64_PC64:
  79             return AUTO_GOTPLT_ENTRY;
  80
  81         case R_X86_64_GOTTPOFF:
  82             return BUILD_GOT_ONLY;
  83
  84         case R_X86_64_GOT32:
  85         case R_X86_64_GOT64:
  86         case R_X86_64_GOTPC32:
  87         case R_X86_64_GOTPC64:
  88         case R_X86_64_GOTOFF64:
  89         case R_X86_64_GOTPCREL:
  90         case R_X86_64_GOTPCRELX:
  91         case R_X86_64_REX_GOTPCRELX:
  92         case R_X86_64_PLT32:
  93         case R_X86_64_PLTOFF64:
  94             return ALWAYS_GOTPLT_ENTRY;
  95     }
  96
  97     tcc_error ("Unknown relocation type: %d", reloc_type);
  98     return -1;
  99 }
 100
 101 ST_FUNC unsigned create_plt_entry(TCCState *s1, unsigned got_offset, struct sym_attr *attr)
 102 {
 103     Section *plt = s1->plt;
 104     uint8_t *p;
 105     int modrm;
 106     unsigned plt_offset, relofs;
 107
 108     modrm = 0x25;
 109
 110     /* empty PLT: create PLT0 entry that pushes the library identifier
 111        (GOT + PTR_SIZE) and jumps to ld.so resolution routine
 112        (GOT + 2 * PTR_SIZE) */
 113     if (plt->data_offset == 0) {
 114         p = section_ptr_add(plt, 16);
 115         p[0] = 0xff; /* pushl got + PTR_SIZE */
 116         p[1] = modrm + 0x10;
 117         write32le(p + 2, PTR_SIZE);
 118         p[6] = 0xff; /* jmp *(got + PTR_SIZE * 2) */
 119         p[7] = modrm;
 120         write32le(p + 8, PTR_SIZE * 2);
 121     }
 122     plt_offset = plt->data_offset;
 123
 124     /* The PLT slot refers to the relocation entry it needs via offset.
 125        The reloc entry is created below, so its offset is the current
 126        data_offset */
 127     relofs = s1->got->reloc ? s1->got->reloc->data_offset : 0;
 128
 129     /* Jump to GOT entry where ld.so initially put the address of ip + 4 */
 130     p = section_ptr_add(plt, 16);
 131     p[0] = 0xff; /* jmp *(got + x) */
 132     p[1] = modrm;
 133     write32le(p + 2, got_offset);
 134     p[6] = 0x68; /* push $xxx */
 135     /* On x86-64, the relocation is referred to by _index_ */
 136     write32le(p + 7, relofs / sizeof (ElfW_Rel));
 137     p[11] = 0xe9; /* jmp plt_start */
 138     write32le(p + 12, -(plt->data_offset));
 139     return plt_offset;
 140 }
 141
 142 /* relocate the PLT: compute addresses and offsets in the PLT now that final
 143    address for PLT and GOT are known (see fill_program_header) */
 144 ST_FUNC void relocate_plt(TCCState *s1)
 145 {
 146     uint8_t *p, *p_end;
 147
 148     if (!s1->plt)
 149       return;
 150
 151     p = s1->plt->data;
 152     p_end = p + s1->plt->data_offset;
 153
 154     if (p < p_end) {
 155         int x = s1->got->sh_addr - s1->plt->sh_addr - 6;
 156         add32le(p + 2, x);
 157         add32le(p + 8, x - 6);
 158         p += 16;
 159         while (p < p_end) {
 160             add32le(p + 2, x + s1->plt->data - p);
 161             p += 16;
 162         }
 163     }
 164 }
 165
 166 static ElfW_Rel *qrel; /* ptr to next reloc entry reused */
 167
 168 void relocate_init(Section *sr)
 169 {
 170     qrel = (ElfW_Rel *) sr->data;
 171 }
 172
 173 void relocate(TCCState *s1, ElfW_Rel *rel, int type, unsigned char *ptr, addr_t addr, addr_t val)
 174 {
 175     int sym_index, esym_index;
 176
 177     sym_index = ELFW(R_SYM)(rel->r_info);
 178
 179     switch (type) {
 180         case R_X86_64_64:
 181             if (s1->output_type == TCC_OUTPUT_DLL) {
 182                 esym_index = s1->sym_attrs[sym_index].dyn_index;
 183                 qrel->r_offset = rel->r_offset;
 184                 if (esym_index) {
 185                     qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_64);
 186                     qrel->r_addend = rel->r_addend;
 187                     qrel++;
 188                     break;
 189                 } else {
 190                     qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE);
 191                     qrel->r_addend = read64le(ptr) + val;
 192                     qrel++;
 193                 }
 194             }
 195             add64le(ptr, val);
 196             break;
 197         case R_X86_64_32:
 198         case R_X86_64_32S:
 199             if (s1->output_type == TCC_OUTPUT_DLL) {
 200                 /* XXX: this logic may depend on TCC's codegen
 201                    now TCC uses R_X86_64_32 even for a 64bit pointer */
 202                 qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE);
 203                 /* Use sign extension! */
 204                 qrel->r_addend = (int)read32le(ptr) + val;
 205                 qrel++;
 206             }
 207             add32le(ptr, val);
 208             break;
 209
 210         case R_X86_64_PC32:
 211             if (s1->output_type == TCC_OUTPUT_DLL) {
 212                 /* DLL relocation */
 213                 esym_index = s1->sym_attrs[sym_index].dyn_index;
 214                 if (esym_index) {
 215                     qrel->r_offset = rel->r_offset;
 216                     qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_PC32);
 217                     /* Use sign extension! */
 218                     qrel->r_addend = (int)read32le(ptr) + rel->r_addend;
 219                     qrel++;
 220                     break;
 221                 }
 222             }
 223             goto plt32pc32;
 224
 225         case R_X86_64_PLT32:
 226             /* fallthrough: val already holds the PLT slot address */
 227
 228         plt32pc32:
 229         {
 230             long long diff;
 231             diff = (long long)val - addr;
 232             if (diff < -2147483648LL || diff > 2147483647LL) {
 233                 tcc_error("internal error: relocation failed");
 234             }
 235             add32le(ptr, diff);
 236         }
 237             break;
 238
 239         case R_X86_64_PLTOFF64:
 240             add64le(ptr, val - s1->got->sh_addr + rel->r_addend);
 241             break;
 242
 243         case R_X86_64_PC64:
 244             if (s1->output_type == TCC_OUTPUT_DLL) {
 245                 /* DLL relocation */
 246                 esym_index = s1->sym_attrs[sym_index].dyn_index;
 247                 if (esym_index) {
 248                     qrel->r_offset = rel->r_offset;
 249                     qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_PC64);
 250                     qrel->r_addend = read64le(ptr) + rel->r_addend;
 251                     qrel++;
 252                     break;
 253                 }
 254             }
 255             add64le(ptr, val - addr);
 256             break;
 257
 258         case R_X86_64_GLOB_DAT:
 259         case R_X86_64_JUMP_SLOT:
 260             /* They don't need addend */
 261             write64le(ptr, val - rel->r_addend);
 262             break;
 263         case R_X86_64_GOTPCREL:
 264         case R_X86_64_GOTPCRELX:
 265         case R_X86_64_REX_GOTPCRELX:
 266             add32le(ptr, s1->got->sh_addr - addr +
 267                          s1->sym_attrs[sym_index].got_offset - 4);
 268             break;
 269         case R_X86_64_GOTPC32:
 270             add32le(ptr, s1->got->sh_addr - addr + rel->r_addend);
 271             break;
 272         case R_X86_64_GOTPC64:
 273             add64le(ptr, s1->got->sh_addr - addr + rel->r_addend);
 274             break;
 275         case R_X86_64_GOTTPOFF:
 276             add32le(ptr, val - s1->got->sh_addr);
 277             break;
 278         case R_X86_64_GOT32:
 279             /* we load the got offset */
 280             add32le(ptr, s1->sym_attrs[sym_index].got_offset);
 281             break;
 282         case R_X86_64_GOT64:
 283             /* we load the got offset */
 284             add64le(ptr, s1->sym_attrs[sym_index].got_offset);
 285             break;
 286         case R_X86_64_GOTOFF64:
 287             add64le(ptr, val - s1->got->sh_addr);
 288             break;
 289         case R_X86_64_RELATIVE:
 290             /* do nothing */
 291             break;
 292     }
 293 }
 294
 295 #endif /* !TARGET_DEFS_ONLY */