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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 lgotno;
  52.     uint32_t *got;
  53.     char *str_tab;
  54.     int i, j;
  55.  
  56.     uint32_t sym_addr;
  57.     module_t *dest;
  58.  
  59.     got = (uint32_t *) m->dyn.plt_got;
  60.     sym_table = m->dyn.sym_tab;
  61.     str_tab = m->dyn.str_tab;
  62.     gotsym = m->dyn.arch.gotsym;
  63.     lgotno = m->dyn.arch.lgotno;
  64.  
  65.     DPRINTF("** Relocate GOT entries **\n");
  66.     DPRINTF("MIPS base = 0x%x\n", m->dyn.arch.base);
  67.  
  68.     /*
  69.      * Local entries.
  70.      */
  71.     for (i = 0; i < gotsym; i++) {
  72.         /* FIXME: really subtract MIPS base? */
  73.         got[i] += m->bias - m->dyn.arch.base;
  74.     }
  75.  
  76.     DPRINTF("sym_ent = %d, gotsym = %d\n", m->dyn.arch.sym_no, gotsym);
  77.     DPRINTF("lgotno = %d\n", lgotno);
  78.  
  79.     /*
  80.      * Iterate over GOT-mapped symbol entries.
  81.      */
  82.     for (j = gotsym; j < m->dyn.arch.sym_no; j++) {
  83.         /* Corresponding (global) GOT entry. */
  84.         i = lgotno + j - gotsym;
  85.  
  86.         DPRINTF("relocate GOT entry %d\n", i);
  87. //      getchar();
  88. //      getchar();
  89.  
  90.         sym = &sym_table[j];
  91.         if (ELF32_R_TYPE(sym->st_info) == STT_FUNC) {
  92.             if (sym->st_shndx == SHN_UNDEF) {
  93.                 if (sym->st_value == 0) {
  94.                     /* 1 */
  95.                 } else {
  96.                     if (got[i] == sym->st_value) {
  97.                         /* 2 */
  98.                         DPRINTF("(2)\n");
  99.                         got[i] += m->bias - m->dyn.arch.base;
  100.                         continue;
  101.                     } else {
  102.                         /* 3 */
  103.                         DPRINTF("(3)\n");
  104.                         got[i] = sym->st_value + m->bias - m->dyn.arch.base;
  105.                         continue;
  106.                     }
  107.                 }
  108.             } else {
  109.                 /* 2 */
  110.                 DPRINTF("(2)\n");
  111.                 got[i] += m->bias - m->dyn.arch.base;
  112.                 continue;
  113.             }
  114.         } else {
  115.             if (sym->st_shndx == SHN_UNDEF ||
  116.                 sym->st_shndx == SHN_COMMON) {
  117.                 /* 1 */
  118.             } else {
  119.                 /* 1 */
  120.             }
  121.         }
  122.        
  123.         DPRINTF("(1) symbol name='%s'\n", str_tab + sym->st_name);
  124.         sym_def = symbol_def_find(str_tab + sym->st_name, m, &dest);
  125.         if (sym_def) {
  126.             sym_addr = symbol_get_addr(sym_def, dest);
  127.             DPRINTF("symbol definition found, addr=0x%x\n", sym_addr);
  128.         } else {
  129.             DPRINTF("symbol definition not found\n");
  130.             continue;
  131.         }
  132.         DPRINTF("write 0x%x at 0x%x\n", sym_addr, (uint32_t) &got[i]);
  133.         got[i] = sym_addr;
  134.     }
  135.  
  136.     DPRINTF("** Done **\n");
  137. }
  138.  
  139. /**
  140.  * Process (fixup) all relocations in a relocation table.
  141.  */
  142. void rel_table_process(module_t *m, elf_rel_t *rt, size_t rt_size)
  143. {
  144.     int i;
  145.  
  146.     size_t rt_entries;
  147.     size_t r_offset;
  148.     elf_word r_info;
  149.     unsigned rel_type;
  150.     elf_word sym_idx;
  151.     uintptr_t sym_addr;
  152.    
  153.     elf_symbol_t *sym_table;
  154.     elf_symbol_t *sym;
  155.     uint32_t *r_ptr;
  156.     uint16_t *r_ptr16;
  157.     char *str_tab;
  158.    
  159.     elf_symbol_t *sym_def;
  160.     module_t *dest;
  161.  
  162.     uint32_t *got;
  163.     uint32_t gotsym;
  164.     uint32_t lgotno;
  165.     uint32_t ea;
  166.  
  167.     DPRINTF("parse relocation table\n");
  168.  
  169.     sym_table = m->dyn.sym_tab;
  170.     rt_entries = rt_size / sizeof(elf_rela_t);
  171.     str_tab = m->dyn.str_tab;
  172.     got = (uint32_t *) m->dyn.plt_got;
  173.     gotsym = m->dyn.arch.gotsym;
  174.     lgotno = m->dyn.arch.lgotno;
  175.  
  176.     DPRINTF("got=0x%lx, gotsym=%d\n", (uintptr_t) got, gotsym);
  177.  
  178.     DPRINTF("address: 0x%x, entries: %d\n", (uintptr_t)rt, rt_entries);
  179.    
  180.     for (i = 0; i < rt_entries; ++i) {
  181.         DPRINTF("symbol %d: ", i);
  182.         r_offset = rt[i].r_offset;
  183.         r_info = rt[i].r_info;
  184.  
  185.         sym_idx = ELF32_R_SYM(r_info);
  186.         sym = &sym_table[sym_idx];
  187.  
  188.         DPRINTF("name '%s', value 0x%x, size 0x%x\n",
  189.             str_tab + sym->st_name,
  190.             sym->st_value,
  191.             sym->st_size);
  192.  
  193.         rel_type = ELF32_R_TYPE(r_info);
  194.         r_ptr = (uint32_t *)(r_offset + m->bias);
  195.         r_ptr16 = (uint16_t *)(r_offset + m->bias);
  196.  
  197.         if (sym->st_name != 0) {
  198.             DPRINTF("rel_type: %x, rel_offset: 0x%x\n", rel_type, r_offset);
  199.             DPRINTF("dest name: '%s'\n", dest->dyn.soname);
  200.             DPRINTF("dest bias: 0x%x\n", dest->bias);
  201.             if (sym_def) {
  202.                 sym_addr = symbol_get_addr(sym_def, dest);
  203.                 DPRINTF("symbol definition found, addr=0x%x\n", sym_addr);
  204.             } else {
  205.                 DPRINTF("symbol definition not found\n");
  206.                 continue;
  207.             }
  208.         }
  209.  
  210.         DPRINTF("switch(%u)\n", rel_type);
  211.  
  212.         switch (rel_type) {
  213.         case R_MIPS_NONE:
  214.             DPRINTF("Ignoring R_MIPS_NONE\n");
  215.             break;
  216.  
  217.         case R_MIPS_REL32:
  218.             DPRINTF("fixup R_MIPS_REL32 (r - ea + s)\n");
  219.             if (sym_idx < gotsym)
  220.                 ea = sym_addr;
  221.             else
  222.                 ea = got[lgotno + sym_idx - gotsym];
  223.  
  224.             *r_ptr += sym_addr - ea;
  225.             DPRINTF("p = 0x%x, val := 0x%x\n", (uint32_t) r_ptr,
  226.                 *r_ptr);
  227. //          getchar();
  228.             break;
  229.  
  230.         /* No other non-TLS relocation types should appear. */
  231.  
  232.         case R_MIPS_TLS_DTPMOD32:
  233.             /*
  234.              * We can ignore this as long as the only module
  235.              * with TLS variables is libc.so.
  236.              */
  237.             DPRINTF("Ignoring R_MIPS_DTPMOD32\n");
  238.             break;
  239.  
  240.         default:
  241.             printf("Error: Unknown relocation type %d.\n",
  242.                 rel_type);
  243.             exit(1);
  244.             break;
  245.         }
  246.     }
  247.  
  248.  
  249.     printf("relocation done\n");
  250. }
  251.  
  252. void rela_table_process(module_t *m, elf_rela_t *rt, size_t rt_size)
  253. {
  254.     /* Unused */
  255.     (void)m; (void)rt; (void)rt_size;
  256. }
  257.  
  258. /** @}
  259.  */
  260.