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2978 | svoboda | 1 | /* |
2 | * Copyright (c) 2008 Jiri Svoboda |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that the following conditions |
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7 | * are met: |
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8 | * |
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9 | * - Redistributions of source code must retain the above copyright |
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10 | * notice, this list of conditions and the following disclaimer. |
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11 | * - Redistributions in binary form must reproduce the above copyright |
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12 | * notice, this list of conditions and the following disclaimer in the |
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13 | * documentation and/or other materials provided with the distribution. |
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14 | * - The name of the author may not be used to endorse or promote products |
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15 | * derived from this software without specific prior written permission. |
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16 | * |
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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27 | */ |
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28 | |||
29 | /** @addtogroup rtld rtld |
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30 | * @brief |
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31 | * @{ |
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32 | */ |
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33 | /** |
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34 | * @file |
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35 | */ |
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36 | |||
37 | #include <stdio.h> |
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38 | #include <stdlib.h> |
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39 | #include <string.h> |
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40 | |||
41 | #include <rtld.h> |
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42 | #include <symbol.h> |
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43 | #include <elf.h> |
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44 | |||
2998 | svoboda | 45 | /* |
46 | * Hash tables are 32-bit (elf_word) even for 64-bit ELF files. |
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47 | */ |
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48 | static elf_word elf_hash(const unsigned char *name) |
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49 | { |
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50 | elf_word h = 0, g; |
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51 | |||
52 | while (*name) { |
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53 | h = (h << 4) + *name++; |
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54 | g = h & 0xf0000000; |
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55 | if (g != 0) h ^= g >> 24; |
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56 | h &= ~g; |
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57 | } |
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58 | |||
59 | return h; |
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60 | } |
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61 | |||
2980 | svoboda | 62 | static elf_symbol_t *def_find_in_module(char *name, module_t *m) |
2978 | svoboda | 63 | { |
64 | elf_symbol_t *sym_table; |
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2998 | svoboda | 65 | elf_symbol_t *s, *sym; |
66 | elf_word nbucket; |
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2978 | svoboda | 67 | elf_word nchain; |
2998 | svoboda | 68 | elf_word i; |
2978 | svoboda | 69 | char *s_name; |
2998 | svoboda | 70 | elf_word bucket; |
2978 | svoboda | 71 | |
2998 | svoboda | 72 | // module_name = m->dyn.soname; |
2981 | svoboda | 73 | // printf("def_find_in_module('%s', %s)\n", name, module_name); |
2978 | svoboda | 74 | |
75 | sym_table = m->dyn.sym_tab; |
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2998 | svoboda | 76 | nbucket = m->dyn.hash[0]; |
2978 | svoboda | 77 | nchain = m->dyn.hash[1]; |
78 | |||
2998 | svoboda | 79 | bucket = elf_hash((unsigned char *)name) % nbucket; |
80 | i = m->dyn.hash[2 + bucket]; |
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81 | |||
82 | sym = NULL; |
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83 | while (i != STN_UNDEF) { |
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84 | s = &sym_table[i]; |
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85 | s_name = m->dyn.str_tab + s->st_name; |
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86 | |||
2978 | svoboda | 87 | if (strcmp(name, s_name) == 0) { |
2998 | svoboda | 88 | sym = s; |
89 | break; |
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2978 | svoboda | 90 | } |
2998 | svoboda | 91 | |
92 | i = m->dyn.hash[2 + nbucket + i]; |
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2978 | svoboda | 93 | } |
94 | |||
2998 | svoboda | 95 | if (!sym) |
96 | return NULL; /* Not found */ |
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97 | |||
98 | if (sym->st_shndx == SHN_UNDEF) { |
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99 | /* Not a definition */ |
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100 | return NULL; |
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101 | } |
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102 | |||
103 | return sym; /* Found */ |
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2978 | svoboda | 104 | } |
105 | |||
2999 | svoboda | 106 | /** Find the definition of a symbol. |
107 | * |
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108 | * By definition in System V ABI, if module origin has the flag DT_SYMBOLIC, |
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109 | * origin is searched first. Otherwise, or if the symbol hasn't been found, |
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110 | * the module dependency graph is searched breadth-first, beginning |
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111 | * from the executable program. |
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112 | * |
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113 | * @param name Name of the symbol to search for. |
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114 | * @param origin Module in which the dependency originates. |
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115 | * @param mod (output) Will be filled with a pointer to the module |
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116 | * that contains the symbol. |
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117 | */ |
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118 | elf_symbol_t *symbol_def_find(char *name, module_t *origin, module_t **mod) |
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2980 | svoboda | 119 | { |
2999 | svoboda | 120 | module_t *m; |
2980 | svoboda | 121 | elf_symbol_t *sym; |
122 | |||
2999 | svoboda | 123 | /* FIXME: support DT_SYMBOLIC */ |
124 | //m = origin; |
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2980 | svoboda | 125 | |
2999 | svoboda | 126 | /* Start in the executable program */ |
127 | m = runtime_env.program; |
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2980 | svoboda | 128 | |
2999 | svoboda | 129 | while (true) { |
130 | sym = def_find_in_module(name, m); |
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131 | if (sym != NULL) { |
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132 | *mod = m; |
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133 | return sym; |
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134 | } |
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2980 | svoboda | 135 | |
2999 | svoboda | 136 | if (m->n_deps < 1) break; |
137 | |||
138 | /* FIXME: support branching */ |
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139 | if (m->n_deps > 1) { |
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140 | printf("error: BFS unimplemented\n"); |
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141 | exit(1); |
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142 | } |
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143 | |||
144 | m = m->deps[0]; |
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145 | } |
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146 | |||
147 | printf("Error, symbol '%s' not found anywhere\n", name); |
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148 | exit(1); |
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149 | return NULL; /* Not found */ |
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2980 | svoboda | 150 | } |
151 | |||
2998 | svoboda | 152 | uintptr_t symbol_get_addr(elf_symbol_t *sym, module_t *m) |
153 | { |
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154 | if (sym->st_shndx == SHN_ABS) { |
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155 | /* Do not add bias to absolute symbols */ |
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156 | return sym->st_value; |
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157 | } else { |
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158 | return sym->st_value + m->bias; |
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159 | } |
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160 | } |
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161 | |||
2978 | svoboda | 162 | /** @} |
163 | */ |