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  1. /*
  2.  * Copyright (c) 2008 Jiri Svoboda
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup rtld rtld
  30.  * @brief
  31.  * @{
  32.  */
  33. /**
  34.  * @file
  35.  */
  36.  
  37. #include <stdio.h>
  38.  
  39. #include <arch.h>
  40. #include <elf_dyn.h>
  41. #include <symbol.h>
  42. #include <rtld.h>
  43.  
  44. /**
  45.  * Process (fixup) all relocations in a relocation table.
  46.  */
  47. void rel_table_process(module_t *m, elf_rel_t *rt, size_t rt_size)
  48. {
  49.     int i;
  50.  
  51.     size_t rt_entries;
  52.     size_t r_offset;
  53.     elf_word r_info;
  54.     unsigned rel_type;
  55.     elf_word sym_idx;
  56.     uintptr_t sym_addr;
  57.    
  58.     elf_symbol_t *sym_table;
  59.     elf_symbol_t *sym;
  60.     uint32_t *r_ptr;
  61.     char *str_tab;
  62.    
  63.     elf_symbol_t *sym_def;
  64.     module_t *dest;
  65.  
  66.     printf("parse relocation table\n");
  67.  
  68.     sym_table = m->dyn.sym_tab;
  69.     rt_entries = rt_size / sizeof(elf_rel_t);
  70.     str_tab = m->dyn.str_tab;
  71.  
  72.     printf("address: 0x%x, entries: %d\n", (uintptr_t)rt, rt_entries);
  73.    
  74.     for (i = 0; i < rt_entries; ++i) {
  75.         printf("symbol %d: ", i);
  76.         r_offset = rt[i].r_offset;
  77.         r_info = rt[i].r_info;
  78.  
  79.         sym_idx = ELF32_R_SYM(r_info);
  80.         sym = &sym_table[sym_idx];
  81.  
  82.         printf("name '%s', value 0x%x, size 0x%x\n",
  83.             str_tab + sym->st_name,
  84.             sym->st_value,
  85.             sym->st_size);
  86.  
  87.         rel_type = ELF32_R_TYPE(r_info);
  88.         r_ptr = (uint32_t *)(r_offset + m->bias);
  89.  
  90.         if (sym->st_name != 0) {
  91.             printf("rel_type: %x, rel_offset: 0x%x\n", rel_type, r_offset);
  92.             sym_def = symbol_def_find(str_tab + sym->st_name, &dest);
  93.             printf("dest name: '%s'\n", dest->dyn.soname);
  94.             printf("dest bias: 0x%x\n", dest->bias);
  95.             if (sym_def) {
  96.                 sym_addr = sym_def->st_value + dest->bias;
  97.                 printf("symbol definition found, addr=0x%x\n", sym_addr);
  98.             } else {
  99.                 printf("symbol definition not found\n");
  100.                 continue;
  101.             }
  102.         }
  103.  
  104.         switch (rel_type) {
  105.         case R_386_GLOB_DAT:
  106.         case R_386_JUMP_SLOT:
  107.             printf("fixup R_386_GLOB_DAT/JUMP_SLOT (b+v)\n");
  108.             *r_ptr = sym_addr;
  109.             break;
  110.  
  111.         case R_386_32:
  112.             printf("fixup R_386_32 (b+v+a)\n");
  113.             *r_ptr += sym_addr;
  114.             break;
  115.            
  116.         case R_386_RELATIVE:
  117.             printf("fixup R_386_RELATIVE (b+a)\n");
  118.             *r_ptr += m->bias;
  119.             break;
  120.         }
  121.     }
  122.  
  123. }
  124.  
  125. /** @}
  126.  */
  127.