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