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2933 | 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 | |||
2952 | svoboda | 37 | void __main(void); |
38 | void __io_init(void); |
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39 | void __exit(void); |
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40 | |||
2933 | svoboda | 41 | void _rtld_main(void); |
42 | |||
43 | #define ELF32_R_SYM(i) ((i)>>8) |
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44 | #define ELF32_R_TYPE(i) ((unsigned char)(i)) |
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45 | |||
46 | typedef struct { |
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47 | int d_tag; |
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48 | union { |
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49 | unsigned d_val; |
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50 | unsigned *d_ptr; |
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51 | } d_un; |
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52 | } elf32_dyn; |
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53 | |||
54 | typedef struct { |
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55 | unsigned r_offset; |
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56 | unsigned r_info; |
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57 | } elf32_rel; |
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58 | |||
59 | typedef struct { |
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60 | unsigned st_name; |
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61 | unsigned st_value; |
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62 | unsigned st_size; |
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63 | unsigned char st_info; |
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64 | unsigned char st_other; |
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65 | unsigned short st_shndx; |
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66 | } elf32_sym; |
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67 | |||
68 | static void kputint(unsigned i) |
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69 | { |
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70 | unsigned dummy; |
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71 | asm volatile ( |
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72 | "movl $30, %%eax;" |
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73 | "int $0x30" |
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74 | : "=d" (dummy) /* output - %edx clobbered */ |
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75 | : "d" (i) /* input */ |
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76 | : "%eax","%ecx" /* all scratch registers clobbered */ |
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77 | ); |
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78 | } |
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79 | |||
80 | void __bootstrap(void) |
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81 | { |
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82 | unsigned bias; |
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83 | unsigned *got; |
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84 | elf32_dyn *dynamic; |
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85 | unsigned *dptr; |
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86 | unsigned dval; |
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87 | int i; |
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88 | |||
89 | unsigned rel_entries; |
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90 | unsigned r_offset; |
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91 | unsigned r_info; |
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92 | unsigned rel_type; |
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93 | unsigned sym_idx; |
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94 | unsigned sym_addr; |
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95 | |||
96 | elf32_sym *sym_table; |
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97 | elf32_rel *rel_table; |
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2952 | svoboda | 98 | elf32_rel *jmp_rel_table; |
99 | elf32_rel *jmp_rel_entries; |
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2933 | svoboda | 100 | |
101 | asm volatile ( |
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102 | "movl $30, %eax;" |
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103 | "int $0x30" |
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104 | ); |
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105 | |||
106 | /* Copied from libc/arch/ia32/entry.s */ |
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107 | /*asm volatile ( |
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108 | "mov %ss, %ax;" |
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109 | "mov %ax, %ds;" |
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110 | "mov %ax, %es;" |
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111 | "mov %ax, %fs;" |
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112 | );*/ |
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113 | |||
114 | |||
115 | asm volatile ( |
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116 | /* Calculate the bias into %0 */ |
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2952 | svoboda | 117 | /* Generates "fake" R_386_RELATIVE run-time relocation */ |
2933 | svoboda | 118 | " call .L0;" |
119 | ".L0: pop %0;" |
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120 | " subl $.L0, %0;" |
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121 | |||
122 | /* Calculate run-time address of _DYNAMIC into %1 */ |
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2952 | svoboda | 123 | /* Generates "fake" R_386_RELATIVE run-time relocation */ |
2933 | svoboda | 124 | " movl $_DYNAMIC, %1;" /* Again, at link time 0-based VMA gets in */ |
125 | " addl %0, %1;" /* Add bias to compute run-time address */ |
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126 | |||
127 | : "=r" (bias), "=r" (dynamic) |
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128 | ); |
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129 | |||
130 | kputint(bias); |
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131 | kputint((unsigned)dynamic); |
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132 | |||
133 | /* parse DYNAMIC */ |
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134 | got = 0; |
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135 | sym_table = 0; |
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136 | rel_table = 0; |
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137 | rel_entries = 0; |
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2952 | svoboda | 138 | jmp_rel_table = 0; |
139 | jmp_rel_entries = 0; |
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2933 | svoboda | 140 | |
141 | i = 0; |
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142 | while (dynamic[i].d_tag != 0) { |
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143 | dptr = (unsigned *)(dynamic[i].d_un.d_val + bias); |
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144 | dval = dynamic[i].d_un.d_val; |
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145 | |||
146 | switch (dynamic[i].d_tag) { |
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2952 | svoboda | 147 | case 2/* DT_PLTRELSZ */: jmp_rel_entries = dval/8; break; |
148 | case 23/* DT_JMPREL */: jmp_rel_table = dptr; break; |
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2933 | svoboda | 149 | case 3 /* DT_PLTGOT */: |
150 | /* GOT address */ |
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151 | got = dptr; break; |
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152 | case 6 /* DT_SYMTAB */ : sym_table = dptr; break; |
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153 | case 17 /* DT_REL */ : rel_table = dptr; break; |
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154 | case 18 /* DT_RELSZ */ : rel_entries = dval / 8; break; |
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155 | default: break; |
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156 | } |
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157 | |||
158 | ++i; |
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159 | } |
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160 | |||
161 | kputint(1); |
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162 | kputint((unsigned)sym_table); |
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163 | kputint((unsigned)rel_table); |
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164 | kputint((unsigned)rel_entries); |
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165 | |||
166 | /* Now relocate all our dynsyms */ |
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167 | kputint(-1); |
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168 | |||
169 | for (i=0; i<rel_entries; i++) { |
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170 | kputint(i); |
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171 | r_offset = rel_table[i].r_offset; |
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172 | r_info = rel_table[i].r_info; |
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173 | |||
174 | rel_type = ELF32_R_TYPE(r_info); |
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175 | |||
176 | kputint(rel_type); |
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177 | kputint(r_offset); |
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178 | |||
2952 | svoboda | 179 | switch (rel_type) { |
180 | case 6: /* R_386_GLOB_DAT */ |
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181 | case 7: /* R_386_JUMP_SLOT */ |
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2933 | svoboda | 182 | kputint(16); |
183 | sym_idx = ELF32_R_SYM(r_info); |
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184 | |||
185 | sym_addr = sym_table[sym_idx].st_value + bias; |
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186 | kputint(sym_idx); |
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187 | kputint(sym_addr); |
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188 | |||
189 | *(unsigned *)(r_offset+bias) = sym_addr; |
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2952 | svoboda | 190 | break; |
191 | |||
192 | case 1: /* R_386_32 */ |
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193 | kputint(16); |
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194 | sym_idx = ELF32_R_SYM(r_info); |
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195 | |||
196 | sym_addr = sym_table[sym_idx].st_value + bias; |
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197 | kputint(sym_idx); |
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198 | kputint(sym_addr); |
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199 | |||
200 | *(unsigned *)(r_offset+bias) += sym_addr; |
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201 | break; |
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202 | |||
203 | case 8: /* R_386_RELATIVE */ |
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204 | kputint(16); |
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205 | *(unsigned *)(r_offset+bias) += bias; |
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206 | break; |
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2933 | svoboda | 207 | } |
208 | } |
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209 | |||
210 | kputint(-1); |
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2952 | svoboda | 211 | |
212 | for (i=0; i<jmp_rel_entries; i++) { |
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213 | kputint(i); |
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214 | r_offset = jmp_rel_table[i].r_offset; |
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215 | r_info = jmp_rel_table[i].r_info; |
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2933 | svoboda | 216 | |
2952 | svoboda | 217 | rel_type = ELF32_R_TYPE(r_info); |
2933 | svoboda | 218 | |
2952 | svoboda | 219 | kputint(rel_type); |
220 | kputint(r_offset); |
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221 | |||
222 | switch (rel_type) { |
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223 | case 6: /* R_386_GLOB_DAT */ |
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224 | case 7: /* R_386_JUMP_SLOT */ |
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225 | kputint(16); |
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226 | sym_idx = ELF32_R_SYM(r_info); |
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227 | |||
228 | sym_addr = sym_table[sym_idx].st_value + bias; |
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229 | kputint(sym_idx); |
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230 | kputint(sym_addr); |
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231 | |||
232 | *(unsigned *)(r_offset+bias) = sym_addr; |
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233 | break; |
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234 | |||
235 | case 1: /* R_386_32 */ |
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236 | kputint(16); |
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237 | sym_idx = ELF32_R_SYM(r_info); |
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238 | |||
239 | sym_addr = sym_table[sym_idx].st_value + bias; |
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240 | kputint(sym_idx); |
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241 | kputint(sym_addr); |
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242 | |||
243 | *(unsigned *)(r_offset+bias) += sym_addr; |
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244 | break; |
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245 | |||
246 | case 8: /* R_386_RELATIVE */ |
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247 | kputint(16); |
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248 | *(unsigned *)(r_offset+bias) += bias; |
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249 | break; |
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250 | } |
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251 | } |
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252 | |||
253 | kputint(-1); |
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254 | |||
255 | /* Init libc and run rtld main */ |
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256 | __main(); |
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257 | |||
258 | kputint(33); |
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259 | __io_init(); |
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260 | kputint(34); |
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2933 | svoboda | 261 | _rtld_main(); |
2952 | svoboda | 262 | kputint(35); |
263 | __exit(); |
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2933 | svoboda | 264 | |
2952 | svoboda | 265 | kputint(36); |
266 | |||
2933 | svoboda | 267 | asm ( |
268 | "movl $250, %%eax;" |
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269 | "int $0x30" |
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270 | : /* output */ |
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271 | : /* input */ |
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272 | : "%eax","%ecx","%edx" /* all scratch registers clobbered */ |
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273 | ); |
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274 | } |
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275 | |||
276 | /** @} |
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277 | */ |