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
  12 #define R_NUM       R_X86_64_NUM
  13
  14 #define ELF_START_ADDR 0x400000
  15 #define ELF_PAGE_SIZE  0x200000
  16
  17 #define PCRELATIVE_DLLPLT 1
  18 #define RELOCATE_DLLPLT 1
  19
  20 #else /* !TARGET_DEFS_ONLY */
  21
  22 #include "tcc.h"
  23
  24 /* Returns 1 for a code relocation, 0 for a data relocation. For unknown
  25    relocations, returns -1. */
  26 int code_reloc (int reloc_type)
  27 {
  28     switch (reloc_type) {
  29         case R_X86_64_32:
  30         case R_X86_64_32S:
  31         case R_X86_64_64:
  32         case R_X86_64_GOTPCREL:
  33         case R_X86_64_GOTPCRELX:
  34         case R_X86_64_REX_GOTPCRELX:
  35         case R_X86_64_GOTTPOFF:
  36         case R_X86_64_GOT32:
  37         case R_X86_64_GLOB_DAT:
  38         case R_X86_64_COPY:
  39         case R_X86_64_RELATIVE:
  40             return 0;
  41
  42         case R_X86_64_PC32:
  43         case R_X86_64_PLT32:
  44         case R_X86_64_JUMP_SLOT:
  45             return 1;
  46     }
  47
  48     tcc_error ("Unknown relocation type: %d", reloc_type);
  49     return -1;
  50 }
  51
  52 /* Returns an enumerator to describe wether and when the relocation needs a
  53    GOT and/or PLT entry to be created. See tcc.h for a description of the
  54    different values. */
  55 int gotplt_entry_type (int reloc_type)
  56 {
  57     switch (reloc_type) {
  58         case R_X86_64_GLOB_DAT:
  59         case R_X86_64_JUMP_SLOT:
  60         case R_X86_64_COPY:
  61         case R_X86_64_RELATIVE:
  62             return NO_GOTPLT_ENTRY;
  63
  64         /* The following relocs wouldn't normally need GOT or PLT
  65            slots, but we need them for simplicity in the link
  66            editor part.  See our caller for comments.  */
  67         case R_X86_64_32:
  68         case R_X86_64_32S:
  69         case R_X86_64_64:
  70         case R_X86_64_PC32:
  71             return AUTO_GOTPLT_ENTRY;
  72
  73         case R_X86_64_GOTTPOFF:
  74             return BUILD_GOT_ONLY;
  75
  76         case R_X86_64_GOT32:
  77         case R_X86_64_GOTPCREL:
  78         case R_X86_64_GOTPCRELX:
  79         case R_X86_64_REX_GOTPCRELX:
  80         case R_X86_64_PLT32:
  81             return ALWAYS_GOTPLT_ENTRY;
  82     }
  83
  84     tcc_error ("Unknown relocation type: %d", reloc_type);
  85     return -1;
  86 }
  87
  88 ST_FUNC unsigned create_plt_entry(TCCState *s1, unsigned got_offset, struct sym_attr *attr)
  89 {
  90     Section *plt = s1->plt;
  91     uint8_t *p;
  92     int modrm;
  93     unsigned plt_offset, relofs;
  94
  95     modrm = 0x25;
  96
  97     /* empty PLT: create PLT0 entry that pushes the library indentifier
  98        (GOT + PTR_SIZE) and jumps to ld.so resolution routine
  99        (GOT + 2 * PTR_SIZE) */
 100     if (plt->data_offset == 0) {
 101         p = section_ptr_add(plt, 16);
 102         p[0] = 0xff; /* pushl got + PTR_SIZE */
 103         p[1] = modrm + 0x10;
 104         write32le(p + 2, PTR_SIZE);
 105         p[6] = 0xff; /* jmp *(got + PTR_SIZE * 2) */
 106         p[7] = modrm;
 107         write32le(p + 8, PTR_SIZE * 2);
 108     }
 109     plt_offset = plt->data_offset;
 110
 111     /* The PLT slot refers to the relocation entry it needs via offset.
 112        The reloc entry is created below, so its offset is the current
 113        data_offset */
 114     relofs = s1->got->reloc ? s1->got->reloc->data_offset : 0;
 115
 116     /* Jump to GOT entry where ld.so initially put the address of ip + 4 */
 117     p = section_ptr_add(plt, 16);
 118     p[0] = 0xff; /* jmp *(got + x) */
 119     p[1] = modrm;
 120     write32le(p + 2, got_offset);
 121     p[6] = 0x68; /* push $xxx */
 122     /* On x86-64, the relocation is referred to by _index_ */
 123     write32le(p + 7, relofs / sizeof (ElfW_Rel));
 124     p[11] = 0xe9; /* jmp plt_start */
 125     write32le(p + 12, -(plt->data_offset));
 126     return plt_offset;
 127 }
 128
 129 /* relocate the PLT: compute addresses and offsets in the PLT now that final
 130    address for PLT and GOT are known (see fill_program_header) */
 131 ST_FUNC void relocate_plt(TCCState *s1)
 132 {
 133     uint8_t *p, *p_end;
 134
 135     if (!s1->plt)
 136       return;
 137
 138     p = s1->plt->data;
 139     p_end = p + s1->plt->data_offset;
 140
 141     if (p < p_end) {
 142         int x = s1->got->sh_addr - s1->plt->sh_addr - 6;
 143         add32le(p + 2, x);
 144         add32le(p + 8, x - 6);
 145         p += 16;
 146         while (p < p_end) {
 147             add32le(p + 2, x + s1->plt->data - p);
 148             p += 16;
 149         }
 150     }
 151 }
 152
 153 static ElfW_Rel *qrel; /* ptr to next reloc entry reused */
 154
 155 void relocate_init(Section *sr)
 156 {
 157     qrel = (ElfW_Rel *) sr->data;
 158 }
 159
 160 void relocate(TCCState *s1, ElfW_Rel *rel, int type, char *ptr, addr_t addr, addr_t val)
 161 {
 162     int sym_index, esym_index;
 163
 164     sym_index = ELFW(R_SYM)(rel->r_info);
 165
 166     switch (type) {
 167         case R_X86_64_64:
 168             if (s1->output_type == TCC_OUTPUT_DLL) {
 169                 esym_index = s1->sym_attrs[sym_index].dyn_index;
 170                 qrel->r_offset = rel->r_offset;
 171                 if (esym_index) {
 172                     qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_64);
 173                     qrel->r_addend = rel->r_addend;
 174                     qrel++;
 175                     break;
 176                 } else {
 177                     qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE);
 178                     qrel->r_addend = read64le(ptr) + val;
 179                     qrel++;
 180                 }
 181             }
 182             add64le(ptr, val);
 183             break;
 184         case R_X86_64_32:
 185         case R_X86_64_32S:
 186             if (s1->output_type == TCC_OUTPUT_DLL) {
 187                 /* XXX: this logic may depend on TCC's codegen
 188                    now TCC uses R_X86_64_32 even for a 64bit pointer */
 189                 qrel->r_info = ELFW(R_INFO)(0, R_X86_64_RELATIVE);
 190                 /* Use sign extension! */
 191                 qrel->r_addend = (int)read32le(ptr) + val;
 192                 qrel++;
 193             }
 194             add32le(ptr, val);
 195             break;
 196
 197         case R_X86_64_PC32:
 198             if (s1->output_type == TCC_OUTPUT_DLL) {
 199                 /* DLL relocation */
 200                 esym_index = s1->sym_attrs[sym_index].dyn_index;
 201                 if (esym_index) {
 202                     qrel->r_offset = rel->r_offset;
 203                     qrel->r_info = ELFW(R_INFO)(esym_index, R_X86_64_PC32);
 204                     /* Use sign extension! */
 205                     qrel->r_addend = (int)read32le(ptr) + rel->r_addend;
 206                     qrel++;
 207                     break;
 208                 }
 209             }
 210             goto plt32pc32;
 211
 212         case R_X86_64_PLT32:
 213             /* fallthrough: val already holds the PLT slot address */
 214
 215         plt32pc32:
 216         {
 217             long long diff;
 218             diff = (long long)val - addr;
 219             if (diff < -2147483648LL || diff > 2147483647LL) {
 220                 tcc_error("internal error: relocation failed");
 221             }
 222             add32le(ptr, diff);
 223         }
 224             break;
 225         case R_X86_64_GLOB_DAT:
 226         case R_X86_64_JUMP_SLOT:
 227             /* They don't need addend */
 228             write64le(ptr, val - rel->r_addend);
 229             break;
 230         case R_X86_64_GOTPCREL:
 231         case R_X86_64_GOTPCRELX:
 232         case R_X86_64_REX_GOTPCRELX:
 233             add32le(ptr, s1->got->sh_addr - addr +
 234                          s1->sym_attrs[sym_index].got_offset - 4);
 235             break;
 236         case R_X86_64_GOTTPOFF:
 237             add32le(ptr, val - s1->got->sh_addr);
 238             break;
 239         case R_X86_64_GOT32:
 240             /* we load the got offset */
 241             add32le(ptr, s1->sym_attrs[sym_index].got_offset);
 242             break;
 243         case R_X86_64_RELATIVE:
 244             /* do nothing */
 245             break;
 246     }
 247 }
 248
 249 #endif /* !TARGET_DEFS_ONLY */