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2996 | 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 | |||
39 | #include <arch.h> |
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40 | #include <elf_dyn.h> |
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41 | #include <symbol.h> |
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42 | #include <rtld.h> |
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43 | |||
44 | #define __L(ptr) ((uint32_t)(ptr) & 0x0000ffff) |
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45 | #define __HA(ptr) ((uint32_t)(ptr) >> 16) |
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46 | |||
47 | // ldis r11, .PLTtable@ha |
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48 | static inline uint32_t _ldis(unsigned rD, uint16_t imm16) |
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49 | { |
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50 | /* Special case of addis: ldis rD,SIMM == addis rD,0,SIMM */ |
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51 | return 0x3C000000 | (rD << 21) | imm16; |
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52 | } |
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53 | |||
54 | static inline uint32_t _lwz(unsigned rD, uint16_t disp16, unsigned rA) |
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55 | { |
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56 | return 0x80000000 | (rD << 21) | (rA << 16) | disp16; |
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57 | } |
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58 | |||
59 | static inline uint32_t _mtctr(unsigned rS) |
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60 | { |
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61 | /* mtctr rD == mtspr 9, rD */ |
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62 | return 0x7c0003a6 | (rS << 21) | (9/*CTR*/ << 16); |
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63 | } |
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64 | |||
65 | static inline uint32_t _bctr() |
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66 | { |
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67 | /* bcctr 0x1f, 0 */ |
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68 | return 0x4c000420 | (0x1f/*always*/ << 21); |
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69 | } |
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70 | |||
71 | /* branch */ |
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72 | static inline uint32_t _b(uint32_t *addr, uint32_t *location) |
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73 | { |
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74 | uint32_t raddr = ((uint32_t)addr - (uint32_t)location) & 0x03fffffc; |
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75 | return 0x48000000 | raddr; |
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76 | } |
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77 | |||
78 | |||
79 | /* |
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80 | * Fill in PLT |
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81 | */ |
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82 | void module_process_pre_arch(module_t *m) |
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83 | { |
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84 | uint32_t *plt; |
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85 | uint32_t *_plt_ent; |
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86 | |||
87 | plt = m->dyn.plt_got; |
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88 | if (!plt) { |
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89 | /* Module has no PLT */ |
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90 | return; |
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91 | } |
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92 | |||
93 | // PLT entries start here. However, each occupies 2 words |
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94 | _plt_ent = plt + 18; |
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95 | |||
96 | // By definition of the ppc ABI, there's 1:1 correspondence |
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97 | // between JMPREL entries and PLT entries |
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98 | unsigned plt_n = m->dyn.plt_rel_sz / sizeof(elf_rela_t); |
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99 | |||
100 | uint32_t *_plt_table; |
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101 | uint32_t *_plt_call; |
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102 | uint32_t *_plt_resolve; |
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103 | |||
104 | _plt_resolve = plt; |
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105 | _plt_call = plt + 6; |
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106 | _plt_table = plt + 18 + plt_n; |
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107 | |||
108 | /* .PLTcall: */ |
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109 | plt[6] = _ldis(11, __HA(_plt_table)); // ldis r11, .PLTtable@ha |
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110 | plt[7] = _lwz(11, __L(_plt_table), 11); // lwz r11, .PLTtable@l(r11) |
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111 | plt[8] = _mtctr(11); // mtctr r11 |
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112 | plt[9] = _bctr(); |
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113 | |||
114 | /* .PLTi, i = 0..N-1 */ |
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115 | // kputint(-4); |
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2997 | svoboda | 116 | /* for (i = 0; i < plt_n; ++i) { |
2996 | svoboda | 117 | //_plt_table[i] == function address; |
118 | plt[18+i] = _b(_plt_call, &plt[18+i]); // b .PLTcall |
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2997 | svoboda | 119 | }*/ |
2996 | svoboda | 120 | } |
121 | |||
122 | void rel_table_process(module_t *m, elf_rel_t *rt, size_t rt_size) |
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123 | { |
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124 | /* Unused */ |
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125 | (void)m; (void)rt; (void)rt_size; |
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126 | } |
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127 | |||
128 | /** |
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129 | * Process (fixup) all relocations in a relocation table. |
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130 | */ |
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131 | void rela_table_process(module_t *m, elf_rela_t *rt, size_t rt_size) |
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132 | { |
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133 | int i; |
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134 | |||
135 | size_t rt_entries; |
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136 | size_t r_offset; |
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137 | elf_word r_info; |
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138 | unsigned rel_type; |
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139 | elf_word sym_idx; |
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140 | uintptr_t sym_addr; |
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141 | uintptr_t r_addend; |
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142 | |||
143 | elf_symbol_t *sym_table; |
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144 | elf_symbol_t *sym; |
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145 | uint32_t *r_ptr; |
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146 | char *str_tab; |
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147 | |||
148 | elf_symbol_t *sym_def; |
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149 | module_t *dest; |
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150 | |||
151 | uint32_t *plt; |
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152 | uint32_t *_plt_table; |
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153 | uint32_t *_plt_ent; |
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154 | uint32_t plt_n; |
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155 | uint32_t pidx; |
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156 | |||
157 | plt = m->dyn.plt_got; |
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158 | plt_n = m->dyn.plt_rel_sz / sizeof(elf_rela_t); |
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159 | _plt_ent = plt+ 18; |
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160 | _plt_table = plt + 18 + plt_n; |
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161 | |||
3589 | svoboda | 162 | DPRINTF("parse relocation table\n"); |
2996 | svoboda | 163 | |
164 | sym_table = m->dyn.sym_tab; |
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165 | rt_entries = rt_size / sizeof(elf_rela_t); |
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166 | str_tab = m->dyn.str_tab; |
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167 | |||
3589 | svoboda | 168 | DPRINTF("address: 0x%x, entries: %d\n", (uintptr_t)rt, rt_entries); |
2996 | svoboda | 169 | |
170 | for (i = 0; i < rt_entries; ++i) { |
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3589 | svoboda | 171 | DPRINTF("symbol %d: ", i); |
2996 | svoboda | 172 | r_offset = rt[i].r_offset; |
173 | r_info = rt[i].r_info; |
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174 | r_addend = rt[i].r_addend; |
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175 | |||
176 | sym_idx = ELF32_R_SYM(r_info); |
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177 | sym = &sym_table[sym_idx]; |
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178 | |||
3589 | svoboda | 179 | DPRINTF("name '%s', value 0x%x, size 0x%x\n", |
2996 | svoboda | 180 | str_tab + sym->st_name, |
181 | sym->st_value, |
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182 | sym->st_size); |
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183 | |||
184 | rel_type = ELF32_R_TYPE(r_info); |
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185 | r_ptr = (uint32_t *)(r_offset + m->bias); |
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186 | |||
187 | if (sym->st_name != 0) { |
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3589 | svoboda | 188 | DPRINTF("rel_type: %x, rel_offset: 0x%x\n", rel_type, r_offset); |
2999 | svoboda | 189 | sym_def = symbol_def_find(str_tab + sym->st_name, |
190 | m, &dest); |
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3589 | svoboda | 191 | DPRINTF("dest name: '%s'\n", dest->dyn.soname); |
192 | DPRINTF("dest bias: 0x%x\n", dest->bias); |
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2996 | svoboda | 193 | if (sym_def) { |
2998 | svoboda | 194 | sym_addr = symbol_get_addr(sym_def, dest); |
3589 | svoboda | 195 | DPRINTF("symbol definition found, addr=0x%x\n", sym_addr); |
2996 | svoboda | 196 | } else { |
3589 | svoboda | 197 | DPRINTF("symbol definition not found\n"); |
2996 | svoboda | 198 | continue; |
199 | } |
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200 | } |
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201 | |||
202 | switch (rel_type) { |
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203 | case R_PPC_JMP_SLOT: |
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3589 | svoboda | 204 | DPRINTF("fixup R_PPC_JMP_SLOT (b+v)\n"); |
2996 | svoboda | 205 | pidx = (r_ptr - _plt_ent) / 2; |
206 | if (pidx >= plt_n) { |
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3589 | svoboda | 207 | DPRINTF("error: proc index out of range\n"); |
2996 | svoboda | 208 | //kputint(0xee00ee0ee00); |
209 | while(1); |
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210 | } |
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2997 | svoboda | 211 | //_plt_table[pidx] = sym_addr; |
2998 | svoboda | 212 | plt[18+2*pidx] = _b((void *)sym_addr, &plt[18+2*pidx]); |
2996 | svoboda | 213 | break; |
214 | |||
215 | case R_PPC_ADDR32: |
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3589 | svoboda | 216 | DPRINTF("fixup R_PPC_ADDR32 (b+v+a)\n"); |
2996 | svoboda | 217 | *r_ptr = r_addend + sym_addr; |
218 | break; |
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219 | |||
220 | case R_PPC_RELATIVE: |
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3589 | svoboda | 221 | DPRINTF("fixup R_PPC_RELATIVE (b+a)\n"); |
2996 | svoboda | 222 | *r_ptr = r_addend + m->bias; |
223 | break; |
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224 | case R_PPC_REL24: |
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3589 | svoboda | 225 | // printf("ignore R_PPC_REL24 at 0x%04x\n", (uintptr_t) r_ptr); |
226 | *r_ptr = (sym_addr + r_addend - (uint32_t)r_ptr) >> 2; |
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227 | DPRINTF("fixup R_PPC_REL24 (s+a-p)>>2\n"); |
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2996 | svoboda | 228 | /*TODO*/ |
229 | break; |
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3589 | svoboda | 230 | default: |
231 | printf("unknown relocation type\n"); |
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232 | break; |
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2996 | svoboda | 233 | } |
234 | } |
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235 | |||
236 | } |
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237 | |||
238 | /** @} |
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239 | */ |