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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 <arch.h>
  41. #include <elf_dyn.h>
  42. #include <symbol.h>
  43. #include <rtld.h>
  44.  
  45. void module_process_pre_arch(module_t *m)
  46. {
  47.     elf_symbol_t *sym_table;
  48.     elf_symbol_t *sym_def;
  49.     elf_symbol_t *sym;
  50.     uint32_t gotsym;
  51.     uint32_t *got;
  52.     char *str_tab;
  53.     int i;
  54.  
  55.     uint32_t sym_addr;
  56.     module_t *dest;
  57.  
  58.     got = (uint32_t *) m->dyn.plt_got;
  59.     sym_table = m->dyn.sym_tab;
  60.     str_tab = m->dyn.str_tab;
  61.     gotsym = m->dyn.arch.gotsym;
  62.  
  63.     DPRINTF("** Relocate GOT entries **\n");
  64.     DPRINTF("MIPS base = 0x%x\n", m->dyn.arch.base);
  65.  
  66.     /*
  67.      * Local entries.
  68.      */
  69.     for (i = 0; i < gotsym; i++) {
  70.         /* FIXME: really subtract MIPS base? */
  71.         got[i] += m->bias - m->dyn.arch.base;
  72.     }
  73.  
  74.     DPRINTF("sym_ent = %d, gotsym = %d\n", m->dyn.arch.sym_no, gotsym);
  75.  
  76.     /*
  77.      * Global entries.
  78.      */
  79.     for (i = gotsym; i < m->dyn.arch.sym_no; i++) {
  80.         DPRINTF("relocate GOT entry %d\n", i);
  81. //      getchar();
  82.  
  83.         sym = &sym_table[i];
  84.         if (ELF32_R_TYPE(sym->st_info) == STT_FUNC) {
  85.             if (sym->st_shndx == SHN_UNDEF) {
  86.                 if (sym->st_value == 0) {
  87.                     /* 1 */
  88.                 } else {
  89.                     if (got[i] == sym->st_value) {
  90.                         /* 2 */
  91.                         DPRINTF("(2)\n");
  92.                         got[i] += m->bias - m->dyn.arch.base;
  93.                         continue;
  94.                     } else {
  95.                         /* 3 */
  96.                         DPRINTF("(3)\n");
  97.                         got[i] = sym->st_value + m->bias - m->dyn.arch.base;
  98.                         continue;
  99.                     }
  100.                 }
  101.             } else {
  102.                 /* 2 */
  103.                 DPRINTF("(2)\n");
  104.                 got[i] += m->bias - m->dyn.arch.base;
  105.                 continue;
  106.             }
  107.         } else {
  108.             if (sym->st_shndx == SHN_UNDEF ||
  109.                 sym->st_shndx == SHN_COMMON) {
  110.                 /* 1 */
  111.             } else {
  112.                 /* 1 */
  113.             }
  114.         }
  115.        
  116.         DPRINTF("(1) symbol name='%s'\n", str_tab + sym->st_name);
  117.         sym_def = symbol_def_find(str_tab + sym->st_name, m, &dest);
  118.         if (sym_def) {
  119.             sym_addr = symbol_get_addr(sym_def, dest);
  120.             DPRINTF("symbol definition found, addr=0x%x\n", sym_addr);
  121.         } else {
  122.             DPRINTF("symbol definition not found\n");
  123.             continue;
  124.         }
  125.         DPRINTF("write 0x%x at 0x%x\n", sym_addr, (uint32_t) &got[i]);
  126. //      getchar();
  127.         got[i] = sym_addr;
  128.     }
  129.  
  130.     DPRINTF("** Done **\n");
  131. }
  132.  
  133. /**
  134.  * Process (fixup) all relocations in a relocation table.
  135.  */
  136. void rel_table_process(module_t *m, elf_rel_t *rt, size_t rt_size)
  137. {
  138.     int i;
  139.  
  140.     size_t rt_entries;
  141.     size_t r_offset;
  142.     elf_word r_info;
  143.     unsigned rel_type;
  144.     elf_word sym_idx;
  145.     uintptr_t sym_addr;
  146.    
  147.     elf_symbol_t *sym_table;
  148.     elf_symbol_t *sym;
  149.     uint32_t *r_ptr;
  150.     uint16_t *r_ptr16;
  151.     char *str_tab;
  152.    
  153.     elf_symbol_t *sym_def;
  154.     module_t *dest;
  155.  
  156.     uint32_t *got;
  157.     uint32_t gotsym;
  158.     uint32_t ea;
  159.  
  160.     DPRINTF("parse relocation table\n");
  161.  
  162.     sym_table = m->dyn.sym_tab;
  163.     rt_entries = rt_size / sizeof(elf_rela_t);
  164.     str_tab = m->dyn.str_tab;
  165.     got = (uint32_t *) m->dyn.plt_got;
  166.     gotsym = m->dyn.arch.gotsym;
  167.  
  168.     DPRINTF("got=0x%lx, gotsym=%d\n", (uintptr_t) got, gotsym);
  169.  
  170.     DPRINTF("address: 0x%x, entries: %d\n", (uintptr_t)rt, rt_entries);
  171.    
  172.     for (i = 0; i < rt_entries; ++i) {
  173.         DPRINTF("symbol %d: ", i);
  174.         r_offset = rt[i].r_offset;
  175.         r_info = rt[i].r_info;
  176.  
  177.         sym_idx = ELF32_R_SYM(r_info);
  178.         sym = &sym_table[sym_idx];
  179.  
  180.         DPRINTF("name '%s', value 0x%x, size 0x%x\n",
  181.             str_tab + sym->st_name,
  182.             sym->st_value,
  183.             sym->st_size);
  184.  
  185.         rel_type = ELF32_R_TYPE(r_info);
  186.         r_ptr = (uint32_t *)(r_offset + m->bias);
  187.         r_ptr16 = (uint16_t *)(r_offset + m->bias);
  188.  
  189.         if (sym->st_name != 0) {
  190.             DPRINTF("rel_type: %x, rel_offset: 0x%x\n", rel_type, r_offset);
  191.             DPRINTF("dest name: '%s'\n", dest->dyn.soname);
  192.             DPRINTF("dest bias: 0x%x\n", dest->bias);
  193.             if (sym_def) {
  194.                 sym_addr = symbol_get_addr(sym_def, dest);
  195.                 DPRINTF("symbol definition found, addr=0x%x\n", sym_addr);
  196.             } else {
  197.                 DPRINTF("symbol definition not found\n");
  198.                 continue;
  199.             }
  200.         }
  201.  
  202.         DPRINTF("switch(%u)\n", rel_type);
  203.  
  204.         switch (rel_type) {
  205.         case R_MIPS_NONE:
  206.             DPRINTF("Ignoring R_MIPS_NONE\n");
  207.             break;
  208.  
  209.         case R_MIPS_REL32:
  210.             DPRINTF("fixup R_MIPS_REL32 (r - ea + s)\n");
  211.             if (sym_idx < gotsym)
  212.                 ea = sym_addr;
  213.             else
  214.                 ea = got[sym_idx];
  215.  
  216.             *r_ptr += sym_addr - ea;
  217.             DPRINTF("p = 0x%x, val := 0x%x\n", (uint32_t) r_ptr,
  218.                 *r_ptr);
  219. //          getchar();
  220.             break;
  221.  
  222.         /* No other non-TLS relocation types should appear. */
  223.  
  224.         case R_MIPS_TLS_DTPMOD32:
  225.             /*
  226.              * We can ignore this as long as the only module
  227.              * with TLS variables is libc.so.
  228.              */
  229.             DPRINTF("Ignoring R_MIPS_DTPMOD32\n");
  230.             break;
  231.  
  232.         default:
  233.             printf("Error: Unknown relocation type %d.\n",
  234.                 rel_type);
  235.             exit(1);
  236.             break;
  237.         }
  238.     }
  239.  
  240.  
  241.     printf("relocation done\n");
  242. }
  243.  
  244. void rela_table_process(module_t *m, elf_rela_t *rt, size_t rt_size)
  245. {
  246.     /* Unused */
  247.     (void)m; (void)rt; (void)rt_size;
  248. }
  249.  
  250. /** @}
  251.  */
  252.