src/system/runtime_loader/arch/x86_64/arch_relocate.cpp

   1 /*
   2  * Copyright 2012, Alex Smith, alex@alex-smith.me.uk.
   3  * Distributed under the terms of the MIT License.
   4  */
   5
   6
   7 #include "runtime_loader_private.h"
   8
   9 #include <runtime_loader.h>
  10
  11 #include <string.h>
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14
  15
  16 static status_t
  17 relocate_rela(image_t* rootImage, image_t* image, Elf64_Rela* rel,
  18         size_t relLength, SymbolLookupCache* cache)
  19 {
  20         for (size_t i = 0; i < relLength / sizeof(Elf64_Rela); i++) {
  21                 int type = ELF64_R_TYPE(rel[i].r_info);
  22                 int symIndex = ELF64_R_SYM(rel[i].r_info);
  23                 Elf64_Addr symAddr = 0;
  24                 image_t* symbolImage = NULL;
  25
  26                 // Resolve the symbol, if any.
  27                 if (symIndex != 0) {
  28                         Elf64_Sym* sym = SYMBOL(image, symIndex);
  29
  30                         status_t status = resolve_symbol(rootImage, image, sym, cache,
  31                                 &symAddr, &symbolImage);
  32                         if (status != B_OK) {
  33                                 TRACE(("resolve symbol \"%s\" returned: %" B_PRId32 "\n",
  34                                         SYMNAME(image, sym), status));
  35                                 printf("resolve symbol \"%s\" returned: %" B_PRId32 "\n",
  36                                         SYMNAME(image, sym), status);
  37                                 return status;
  38                         }
  39                 }
  40
  41                 // Address of the relocation.
  42                 Elf64_Addr relocAddr = image->regions[0].delta + rel[i].r_offset;
  43
  44                 // Calculate the relocation value.
  45                 Elf64_Addr relocValue;
  46                 switch(type) {
  47                         case R_X86_64_NONE:
  48                                 continue;
  49                         case R_X86_64_64:
  50                         case R_X86_64_GLOB_DAT:
  51                         case R_X86_64_JUMP_SLOT:
  52                                 relocValue = symAddr + rel[i].r_addend;
  53                                 break;
  54                         case R_X86_64_PC32:
  55                                 relocValue = symAddr + rel[i].r_addend - rel[i].r_offset;
  56                                 break;
  57                         case R_X86_64_RELATIVE:
  58                                 relocValue = image->regions[0].delta + rel[i].r_addend;
  59                                 break;
  60                         case R_X86_64_DTPMOD64:
  61                                 relocValue = symbolImage == NULL
  62                                                         ? image->dso_tls_id : symbolImage->dso_tls_id;
  63                                 break;
  64                         case R_X86_64_DTPOFF32:
  65                         case R_X86_64_DTPOFF64:
  66                                 relocValue = symAddr;
  67                                 break;
  68                         default:
  69                                 TRACE(("unhandled relocation type %d\n", type));
  70                                 return B_BAD_DATA;
  71                 }
  72
  73                 *(Elf64_Addr *)relocAddr = relocValue;
  74         }
  75
  76         return B_OK;
  77 }
  78
  79
  80 status_t
  81 arch_relocate_image(image_t* rootImage, image_t* image,
  82         SymbolLookupCache* cache)
  83 {
  84         status_t status;
  85
  86         // No REL on x86_64.
  87
  88         // Perform RELA relocations.
  89         if (image->rela) {
  90                 status = relocate_rela(rootImage, image, image->rela, image->rela_len,
  91                         cache);
  92                 if (status != B_OK)
  93                         return status;
  94         }
  95
  96         // PLT relocations (they are RELA on x86_64).
  97         if (image->pltrel) {
  98                 status = relocate_rela(rootImage, image, (Elf64_Rela*)image->pltrel,
  99                         image->pltrel_len, cache);
 100                 if (status != B_OK)
 101                         return status;
 102         }
 103
 104         return B_OK;
 105 }