arm-link.c

   1 #ifdef TARGET_DEFS_ONLY
   2
   3 #define EM_TCC_TARGET EM_ARM
   4
   5 /* relocation type for 32 bit data relocation */
   6 #define R_DATA_32   R_ARM_ABS32
   7 #define R_DATA_PTR  R_ARM_ABS32
   8 #define R_JMP_SLOT  R_ARM_JUMP_SLOT
   9 #define R_GLOB_DAT  R_ARM_GLOB_DAT
  10 #define R_COPY      R_ARM_COPY
  11
  12 #define R_NUM       R_ARM_NUM
  13
  14 #define ELF_START_ADDR 0x00008000
  15 #define ELF_PAGE_SIZE  0x1000
  16
  17 #define HAVE_SECTION_RELOC
  18
  19 enum float_abi {
  20     ARM_SOFTFP_FLOAT,
  21     ARM_HARD_FLOAT,
  22 };
  23
  24 #else /* !TARGET_DEFS_ONLY */
  25
  26 #include "tcc.h"
  27
  28 ST_DATA struct reloc_info relocs_info[R_NUM] = {
  29     INIT_RELOC_INFO (R_ARM_PC24, 1, AUTO_GOTPLT_ENTRY, 0)
  30     INIT_RELOC_INFO (R_ARM_CALL, 1, AUTO_GOTPLT_ENTRY, 0)
  31     INIT_RELOC_INFO (R_ARM_JUMP24, 1, AUTO_GOTPLT_ENTRY, 0)
  32     INIT_RELOC_INFO (R_ARM_PLT32, 1, ALWAYS_GOTPLT_ENTRY, 0)
  33     INIT_RELOC_INFO (R_ARM_THM_PC22, 1, AUTO_GOTPLT_ENTRY, 0)
  34     INIT_RELOC_INFO (R_ARM_THM_JUMP24, 1, AUTO_GOTPLT_ENTRY, 0)
  35     INIT_RELOC_INFO (R_ARM_MOVT_ABS, 0, AUTO_GOTPLT_ENTRY, 0)
  36     INIT_RELOC_INFO (R_ARM_MOVW_ABS_NC, 0, AUTO_GOTPLT_ENTRY, 0)
  37     INIT_RELOC_INFO (R_ARM_THM_MOVT_ABS, 0, AUTO_GOTPLT_ENTRY, 0)
  38     INIT_RELOC_INFO (R_ARM_THM_MOVW_ABS_NC, 0, AUTO_GOTPLT_ENTRY, 0)
  39     INIT_RELOC_INFO (R_ARM_PREL31, 1, AUTO_GOTPLT_ENTRY, 0)
  40     INIT_RELOC_INFO (R_ARM_ABS32, 0, AUTO_GOTPLT_ENTRY, 0)
  41     INIT_RELOC_INFO (R_ARM_REL32, 0, AUTO_GOTPLT_ENTRY, 0)
  42     INIT_RELOC_INFO (R_ARM_GOTPC, 0, BUILD_GOT_ONLY, 0)
  43     INIT_RELOC_INFO (R_ARM_GOTOFF, 0, BUILD_GOT_ONLY, 0)
  44     INIT_RELOC_INFO (R_ARM_GOT32, 0, ALWAYS_GOTPLT_ENTRY, 0)
  45     INIT_RELOC_INFO (R_ARM_COPY, 0, NO_GOTPLT_ENTRY, 0)
  46     INIT_RELOC_INFO (R_ARM_V4BX, 1, AUTO_GOTPLT_ENTRY, 0)
  47     INIT_RELOC_INFO (R_ARM_GLOB_DAT, 0, NO_GOTPLT_ENTRY, 0)
  48     INIT_RELOC_INFO (R_ARM_JUMP_SLOT, 1, NO_GOTPLT_ENTRY, 0)
  49     INIT_RELOC_INFO (R_ARM_NONE, 0, NO_GOTPLT_ENTRY, 0)
  50 };
  51
  52 void relocate_init(Section *sr) {}
  53
  54 void relocate(TCCState *s1, ElfW_Rel *rel, int type, char *ptr, addr_t addr, addr_t val)
  55 {
  56     ElfW(Sym) *sym;
  57     int sym_index;
  58
  59     sym_index = ELFW(R_SYM)(rel->r_info);
  60     sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
  61
  62     switch(type) {
  63         case R_ARM_PC24:
  64         case R_ARM_CALL:
  65         case R_ARM_JUMP24:
  66         case R_ARM_PLT32:
  67             {
  68                 int x, is_thumb, is_call, h, blx_avail, is_bl, th_ko;
  69                 x = (*(int *) ptr) & 0xffffff;
  70 #ifdef DEBUG_RELOC
  71                 printf ("reloc %d: x=0x%x val=0x%x ", type, x, val);
  72 #endif
  73                 (*(int *)ptr) &= 0xff000000;
  74                 if (x & 0x800000)
  75                     x -= 0x1000000;
  76                 x <<= 2;
  77                 blx_avail = (TCC_ARM_VERSION >= 5);
  78                 is_thumb = val & 1;
  79                 is_bl = (*(unsigned *) ptr) >> 24 == 0xeb;
  80                 is_call = (type == R_ARM_CALL || (type == R_ARM_PC24 && is_bl));
  81                 x += val - addr;
  82 #ifdef DEBUG_RELOC
  83                 printf (" newx=0x%x name=%s\n", x,
  84                         (char *) symtab_section->link->data + sym->st_name);
  85 #endif
  86                 h = x & 2;
  87                 th_ko = (x & 3) && (!blx_avail || !is_call);
  88                 if (th_ko || x >= 0x2000000 || x < -0x2000000)
  89                     tcc_error("can't relocate value at %x,%d",addr, type);
  90                 x >>= 2;
  91                 x &= 0xffffff;
  92                 /* Only reached if blx is avail and it is a call */
  93                 if (is_thumb) {
  94                     x |= h << 24;
  95                     (*(int *)ptr) = 0xfa << 24; /* bl -> blx */
  96                 }
  97                 (*(int *) ptr) |= x;
  98             }
  99             return;
 100         /* Since these relocations only concern Thumb-2 and blx instruction was
 101            introduced before Thumb-2, we can assume blx is available and not
 102            guard its use */
 103         case R_ARM_THM_PC22:
 104         case R_ARM_THM_JUMP24:
 105             {
 106                 int x, hi, lo, s, j1, j2, i1, i2, imm10, imm11;
 107                 int to_thumb, is_call, to_plt, blx_bit = 1 << 12;
 108                 Section *plt;
 109
 110                 /* weak reference */
 111                 if (sym->st_shndx == SHN_UNDEF &&
 112                     ELFW(ST_BIND)(sym->st_info) == STB_WEAK)
 113                     return;
 114
 115                 /* Get initial offset */
 116                 hi = (*(uint16_t *)ptr);
 117                 lo = (*(uint16_t *)(ptr+2));
 118                 s = (hi >> 10) & 1;
 119                 j1 = (lo >> 13) & 1;
 120                 j2 = (lo >> 11) & 1;
 121                 i1 = (j1 ^ s) ^ 1;
 122                 i2 = (j2 ^ s) ^ 1;
 123                 imm10 = hi & 0x3ff;
 124                 imm11 = lo & 0x7ff;
 125                 x = (s << 24) | (i1 << 23) | (i2 << 22) |
 126                     (imm10 << 12) | (imm11 << 1);
 127                 if (x & 0x01000000)
 128                     x -= 0x02000000;
 129
 130                 /* Relocation infos */
 131                 to_thumb = val & 1;
 132                 plt = s1->plt;
 133                 to_plt = (val >= plt->sh_addr) &&
 134                          (val < plt->sh_addr + plt->data_offset);
 135                 is_call = (type == R_ARM_THM_PC22);
 136
 137                 if (!to_thumb && !to_plt && !is_call) {
 138                     int index;
 139                     uint8_t *p;
 140                     char *name, buf[1024];
 141                     Section *text_section;
 142
 143                     name = (char *) symtab_section->link->data + sym->st_name;
 144                     text_section = s1->sections[sym->st_shndx];
 145                     /* Modify reloc to target a thumb stub to switch to ARM */
 146                     snprintf(buf, sizeof(buf), "%s_from_thumb", name);
 147                     index = put_elf_sym(symtab_section,
 148                                         text_section->data_offset + 1,
 149                                         sym->st_size, sym->st_info, 0,
 150                                         sym->st_shndx, buf);
 151                     to_thumb = 1;
 152                     val = text_section->data_offset + 1;
 153                     rel->r_info = ELFW(R_INFO)(index, type);
 154                     /* Create a thumb stub function to switch to ARM mode */
 155                     put_elf_reloc(symtab_section, text_section,
 156                                   text_section->data_offset + 4, R_ARM_JUMP24,
 157                                   sym_index);
 158                     p = section_ptr_add(text_section, 8);
 159                     write32le(p,   0x4778); /* bx pc */
 160                     write32le(p+2, 0x46c0); /* nop   */
 161                     write32le(p+4, 0xeafffffe); /* b $sym */
 162                 }
 163
 164                 /* Compute final offset */
 165                 x += val - addr;
 166                 if (!to_thumb && is_call) {
 167                     blx_bit = 0; /* bl -> blx */
 168                     x = (x + 3) & -4; /* Compute offset from aligned PC */
 169                 }
 170
 171                 /* Check that relocation is possible
 172                    * offset must not be out of range
 173                    * if target is to be entered in arm mode:
 174                      - bit 1 must not set
 175                      - instruction must be a call (bl) or a jump to PLT */
 176                 if (!to_thumb || x >= 0x1000000 || x < -0x1000000)
 177                     if (to_thumb || (val & 2) || (!is_call && !to_plt))
 178                         tcc_error("can't relocate value at %x,%d",addr, type);
 179
 180                 /* Compute and store final offset */
 181                 s = (x >> 24) & 1;
 182                 i1 = (x >> 23) & 1;
 183                 i2 = (x >> 22) & 1;
 184                 j1 = s ^ (i1 ^ 1);
 185                 j2 = s ^ (i2 ^ 1);
 186                 imm10 = (x >> 12) & 0x3ff;
 187                 imm11 = (x >> 1) & 0x7ff;
 188                 (*(uint16_t *)ptr) = (uint16_t) ((hi & 0xf800) |
 189                                      (s << 10) | imm10);
 190                 (*(uint16_t *)(ptr+2)) = (uint16_t) ((lo & 0xc000) |
 191                                 (j1 << 13) | blx_bit | (j2 << 11) |
 192                                 imm11);
 193             }
 194             return;
 195         case R_ARM_MOVT_ABS:
 196         case R_ARM_MOVW_ABS_NC:
 197             {
 198                 int x, imm4, imm12;
 199                 if (type == R_ARM_MOVT_ABS)
 200                     val >>= 16;
 201                 imm12 = val & 0xfff;
 202                 imm4 = (val >> 12) & 0xf;
 203                 x = (imm4 << 16) | imm12;
 204                 if (type == R_ARM_THM_MOVT_ABS)
 205                     *(int *)ptr |= x;
 206                 else
 207                     *(int *)ptr += x;
 208             }
 209             return;
 210         case R_ARM_THM_MOVT_ABS:
 211         case R_ARM_THM_MOVW_ABS_NC:
 212             {
 213                 int x, i, imm4, imm3, imm8;
 214                 if (type == R_ARM_THM_MOVT_ABS)
 215                     val >>= 16;
 216                 imm8 = val & 0xff;
 217                 imm3 = (val >> 8) & 0x7;
 218                 i = (val >> 11) & 1;
 219                 imm4 = (val >> 12) & 0xf;
 220                 x = (imm3 << 28) | (imm8 << 16) | (i << 10) | imm4;
 221                 if (type == R_ARM_THM_MOVT_ABS)
 222                     *(int *)ptr |= x;
 223                 else
 224                     *(int *)ptr += x;
 225             }
 226             return;
 227         case R_ARM_PREL31:
 228             {
 229                 int x;
 230                 x = (*(int *)ptr) & 0x7fffffff;
 231                 (*(int *)ptr) &= 0x80000000;
 232                 x = (x * 2) / 2;
 233                 x += val - addr;
 234                 if((x^(x>>1))&0x40000000)
 235                     tcc_error("can't relocate value at %x,%d",addr, type);
 236                 (*(int *)ptr) |= x & 0x7fffffff;
 237             }
 238         case R_ARM_ABS32:
 239             *(int *)ptr += val;
 240             return;
 241         case R_ARM_REL32:
 242             *(int *)ptr += val - addr;
 243             return;
 244         case R_ARM_GOTPC:
 245             *(int *)ptr += s1->got->sh_addr - addr;
 246             return;
 247         case R_ARM_GOTOFF:
 248             *(int *)ptr += val - s1->got->sh_addr;
 249             return;
 250         case R_ARM_GOT32:
 251             /* we load the got offset */
 252             *(int *)ptr += s1->sym_attrs[sym_index].got_offset;
 253             return;
 254         case R_ARM_COPY:
 255             return;
 256         case R_ARM_V4BX:
 257             /* trade Thumb support for ARMv4 support */
 258             if ((0x0ffffff0 & *(int*)ptr) == 0x012FFF10)
 259                 *(int*)ptr ^= 0xE12FFF10 ^ 0xE1A0F000; /* BX Rm -> MOV PC, Rm */
 260             return;
 261         case R_ARM_GLOB_DAT:
 262         case R_ARM_JUMP_SLOT:
 263             *(addr_t *)ptr = val;
 264             return;
 265         case R_ARM_NONE:
 266             /* Nothing to do.  Normally used to indicate a dependency
 267                on a certain symbol (like for exception handling under EABI).  */
 268             return;
 269         default:
 270             fprintf(stderr,"FIXME: handle reloc type %x at %x [%p] to %x\n",
 271                 type, (unsigned)addr, ptr, (unsigned)val);
 272             return;
 273     }
 274 }
 275
 276 #endif /* !TARGET_DEFS_ONLY */