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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. #include <stdlib.h>
  39.  
  40. #include <elf_dyn.h>
  41. #include <symbol.h>
  42. #include <rtld.h>
  43.  
  44. #include <rtld_arch.h>
  45.  
  46. void module_process_pre_arch(module_t *m)
  47. {
  48.     /* Unused */
  49. }
  50.  
  51.  
  52. /**
  53.  * Process (fixup) all relocations in a relocation table.
  54.  */
  55. void rel_table_process(module_t *m, elf_rel_t *rt, size_t rt_size)
  56. {
  57.     int i;
  58.  
  59.     size_t rt_entries;
  60.     size_t r_offset;
  61.     elf_word r_info;
  62.     unsigned rel_type;
  63.     elf_word sym_idx;
  64.     uintptr_t sym_addr;
  65.    
  66.     elf_symbol_t *sym_table;
  67.     elf_symbol_t *sym;
  68.     uint32_t *r_ptr;
  69.     uint32_t sym_size;
  70.     char *str_tab;
  71.    
  72.     elf_symbol_t *sym_def;
  73.     module_t *dest;
  74.  
  75.     DPRINTF("parse relocation table\n");
  76.  
  77.     sym_table = m->dyn.sym_tab;
  78.     rt_entries = rt_size / sizeof(elf_rel_t);
  79.     str_tab = m->dyn.str_tab;
  80.  
  81.     DPRINTF("address: 0x%x, entries: %d\n", (uintptr_t)rt, rt_entries);
  82.    
  83.     for (i = 0; i < rt_entries; ++i) {
  84. //      DPRINTF("symbol %d: ", i);
  85.         r_offset = rt[i].r_offset;
  86.         r_info = rt[i].r_info;
  87.  
  88.         sym_idx = ELF32_R_SYM(r_info);
  89.         sym = &sym_table[sym_idx];
  90.  
  91. /*      DPRINTF("name '%s', value 0x%x, size 0x%x\n",
  92.             str_tab + sym->st_name,
  93.             sym->st_value,
  94.             sym->st_size);
  95. */
  96.         rel_type = ELF32_R_TYPE(r_info);
  97.         r_ptr = (uint32_t *)(r_offset + m->bias);
  98.  
  99.         if (sym->st_name != 0) {
  100. //          DPRINTF("rel_type: %x, rel_offset: 0x%x\n", rel_type, r_offset);
  101.             sym_def = symbol_def_find(str_tab + sym->st_name,
  102.                 m, &dest);
  103. //          DPRINTF("dest name: '%s'\n", dest->dyn.soname);
  104. //          DPRINTF("dest bias: 0x%x\n", dest->bias);
  105.             if (sym_def) {
  106.                 sym_addr = symbol_get_addr(sym_def, dest);
  107. //              DPRINTF("symbol definition found, addr=0x%x\n", sym_addr);
  108.             } else {
  109.                 printf("Definition of '%s' not found.\n",
  110.                     str_tab + sym->st_name);
  111.                 continue;
  112.             }
  113.         }
  114.  
  115.         switch (rel_type) {
  116.         case R_386_GLOB_DAT:
  117.         case R_386_JUMP_SLOT:
  118.             DPRINTF("fixup R_386_GLOB_DAT/JUMP_SLOT (b+v)\n");
  119.             *r_ptr = sym_addr;
  120.             break;
  121.  
  122.         case R_386_32:
  123.             DPRINTF("fixup R_386_32 (b+v+a)\n");
  124.             *r_ptr += sym_addr;
  125.             break;
  126.  
  127.         case R_386_PC32:
  128.             DPRINTF("fixup R_386_PC32 (b+v+a-p)\n");
  129.             *r_ptr += sym_addr - (uint32_t) r_ptr;
  130.             break;
  131.  
  132.         case R_386_COPY:
  133.             /*
  134.              * Copy symbol data from shared object to specified
  135.              * location.
  136.              */
  137.             DPRINTF("fixup R_386_COPY (s)\n");
  138.             sym_size = sym->st_size;
  139.             if (sym_size != sym_def->st_size) {
  140.                 printf("Warning: Mismatched symbol sizes.\n");
  141.                 /* Take the lower value. */
  142.                 if (sym_size > sym_def->st_size)
  143.                     sym_size = sym_def->st_size;
  144.             }
  145.             memcpy(r_ptr, (const void *)sym_addr, sym_size);
  146.             break;
  147.            
  148.         case R_386_RELATIVE:
  149.             DPRINTF("fixup R_386_RELATIVE (b+a)\n");
  150.             *r_ptr += m->bias;
  151.             break;
  152.  
  153.         case R_386_TLS_DTPMOD32:
  154.             /*
  155.              * We can ignore this as long as the only module
  156.              * with TLS variables is libc.so.
  157.              */
  158.             DPRINTF("Ignoring R_386_TLS_DTPMOD32\n");
  159.             break;
  160.  
  161.         default:
  162.             printf("Error: Unknown relocation type %d\n",
  163.                 rel_type);
  164.             exit(1);
  165.         }
  166.  
  167.     }
  168.  
  169. }
  170.  
  171. void rela_table_process(module_t *m, elf_rela_t *rt, size_t rt_size)
  172. {
  173.     /* Unused */
  174.     (void)m; (void)rt; (void)rt_size;
  175. }
  176.  
  177. /** @}
  178.  */
  179.