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2928 | svoboda | 1 | /* |
2 | * Copyright (c) 2006 Sergey Bondari |
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3 | * Copyright (c) 2006 Jakub Jermar |
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4 | * Copyright (c) 2008 Jiri Svoboda |
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5 | * All rights reserved. |
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6 | * |
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7 | * Redistribution and use in source and binary forms, with or without |
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8 | * modification, are permitted provided that the following conditions |
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9 | * are met: |
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10 | * |
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11 | * - Redistributions of source code must retain the above copyright |
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12 | * notice, this list of conditions and the following disclaimer. |
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13 | * - Redistributions in binary form must reproduce the above copyright |
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14 | * notice, this list of conditions and the following disclaimer in the |
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15 | * documentation and/or other materials provided with the distribution. |
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16 | * - The name of the author may not be used to endorse or promote products |
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17 | * derived from this software without specific prior written permission. |
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18 | * |
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19 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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20 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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21 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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22 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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23 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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24 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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25 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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26 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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27 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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28 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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29 | */ |
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30 | |||
31 | /** @addtogroup generic |
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32 | * @{ |
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33 | */ |
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34 | |||
35 | /** |
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36 | * @file |
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37 | * @brief Kernel ELF loader. |
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38 | */ |
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39 | |||
40 | #include <stdio.h> |
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41 | #include <sys/types.h> |
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42 | #include <align.h> |
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43 | #include <assert.h> |
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44 | #include <as.h> |
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2962 | svoboda | 45 | #include <unistd.h> |
46 | #include <fcntl.h> |
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47 | |||
2928 | svoboda | 48 | #include "elf.h" |
2962 | svoboda | 49 | #include "pcb.h" |
50 | #include "elf_load.h" |
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2928 | svoboda | 51 | |
2932 | svoboda | 52 | #define RTLD_BIAS 0x80000 |
2949 | svoboda | 53 | //#define RTLD_BIAS 0 |
2928 | svoboda | 54 | |
55 | static char *error_codes[] = { |
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56 | "no error", |
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57 | "invalid image", |
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58 | "address space error", |
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59 | "incompatible image", |
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60 | "unsupported image type", |
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61 | "irrecoverable error" |
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62 | }; |
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63 | |||
2964 | svoboda | 64 | static unsigned int elf_load(elf_ld_t *elf); |
65 | static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry); |
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66 | static int section_header(elf_ld_t *elf, elf_section_header_t *entry); |
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67 | static int load_segment(elf_ld_t *elf, elf_segment_header_t *entry); |
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2928 | svoboda | 68 | |
2964 | svoboda | 69 | int elf_load_file(char *file_name, elf_info_t *info) |
70 | { |
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71 | elf_ld_t elf; |
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2928 | svoboda | 72 | |
2962 | svoboda | 73 | int fd; |
74 | int rc; |
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75 | |||
76 | printf("open and read '%s'...\n", file_name); |
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77 | |||
78 | fd = open(file_name, 0); |
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79 | if (fd < 0) { |
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80 | printf("failed opening file\n"); |
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81 | return -1; |
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82 | } |
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83 | |||
2964 | svoboda | 84 | elf.fd = fd; |
85 | elf.info = info; |
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86 | |||
87 | rc = elf_load(&elf); |
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2962 | svoboda | 88 | printf("elf_load() -> %d\n", rc); |
89 | |||
90 | close(fd); |
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91 | |||
92 | return rc; |
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93 | } |
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94 | |||
2964 | svoboda | 95 | void elf_run(elf_info_t *info) |
2962 | svoboda | 96 | { |
2964 | svoboda | 97 | (*info->entry)(); |
2962 | svoboda | 98 | |
99 | /* not reached */ |
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100 | } |
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101 | |||
2964 | svoboda | 102 | int elf_create_pcb(elf_info_t *info) |
2962 | svoboda | 103 | { |
104 | pcb_t *pcb; |
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105 | void *a; |
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106 | |||
107 | pcb = (pcb_t *)PCB_ADDRESS; |
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108 | |||
109 | a = as_area_create(pcb, sizeof(pcb_t), AS_AREA_READ | AS_AREA_WRITE); |
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110 | if (a == (void *)(-1)) { |
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111 | printf("elf_create_pcb: memory mapping failed\n"); |
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112 | return EE_MEMORY; |
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113 | } |
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114 | |||
2964 | svoboda | 115 | pcb->entry = info->entry; |
2965 | svoboda | 116 | pcb->dynamic = info->dynamic; |
2962 | svoboda | 117 | |
118 | return 0; |
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119 | } |
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120 | |||
121 | |||
2928 | svoboda | 122 | /** ELF loader |
123 | * |
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124 | * @param header Pointer to ELF header in memory |
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125 | * @return EE_OK on success |
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126 | */ |
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2964 | svoboda | 127 | static unsigned int elf_load(elf_ld_t *elf) |
2928 | svoboda | 128 | { |
2964 | svoboda | 129 | elf_header_t header_buf; |
130 | elf_header_t *header = &header_buf; |
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2928 | svoboda | 131 | int i, rc; |
132 | |||
2964 | svoboda | 133 | rc = read(elf->fd, header, sizeof(elf_header_t)); |
2928 | svoboda | 134 | if (rc < 0) { |
135 | printf("read error\n"); |
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136 | return EE_INVALID; |
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137 | } |
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138 | |||
2964 | svoboda | 139 | elf->header = header; |
140 | |||
2928 | svoboda | 141 | printf("ELF-load:"); |
142 | /* Identify ELF */ |
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143 | if (header->e_ident[EI_MAG0] != ELFMAG0 || |
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144 | header->e_ident[EI_MAG1] != ELFMAG1 || |
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145 | header->e_ident[EI_MAG2] != ELFMAG2 || |
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146 | header->e_ident[EI_MAG3] != ELFMAG3) { |
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147 | printf("invalid header\n"); |
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148 | return EE_INVALID; |
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149 | } |
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150 | |||
151 | /* Identify ELF compatibility */ |
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152 | if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING || |
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153 | header->e_machine != ELF_MACHINE || |
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154 | header->e_ident[EI_VERSION] != EV_CURRENT || |
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155 | header->e_version != EV_CURRENT || |
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156 | header->e_ident[EI_CLASS] != ELF_CLASS) { |
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157 | printf("incompatible data/version/class\n"); |
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158 | return EE_INCOMPATIBLE; |
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159 | } |
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160 | |||
161 | if (header->e_phentsize != sizeof(elf_segment_header_t)) |
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162 | return EE_INCOMPATIBLE; |
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163 | |||
164 | if (header->e_shentsize != sizeof(elf_section_header_t)) |
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165 | return EE_INCOMPATIBLE; |
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166 | |||
167 | /* Check if the object type is supported. */ |
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168 | if (header->e_type != ET_EXEC && header->e_type != ET_DYN) { |
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169 | printf("Object type %d is not supported\n", header->e_type); |
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170 | return EE_UNSUPPORTED; |
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171 | } |
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172 | |||
2964 | svoboda | 173 | /* The run-time dynamic linker is loaded with a bias */ |
174 | if (header->e_type == ET_DYN) |
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175 | elf->bias = RTLD_BIAS; |
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176 | else |
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177 | elf->bias = 0; |
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178 | |||
2928 | svoboda | 179 | printf("parse segments\n"); |
180 | |||
181 | /* Walk through all segment headers and process them. */ |
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182 | for (i = 0; i < header->e_phnum; i++) { |
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2964 | svoboda | 183 | elf_segment_header_t segment_hdr; |
2928 | svoboda | 184 | |
2961 | svoboda | 185 | /* Seek to start of segment header */ |
2964 | svoboda | 186 | lseek(elf->fd, header->e_phoff |
187 | + i * sizeof(elf_segment_header_t), SEEK_SET); |
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2928 | svoboda | 188 | |
2964 | svoboda | 189 | rc = read(elf->fd, &segment_hdr, sizeof(elf_segment_header_t)); |
190 | if (rc < 0) { printf("read error\n"); return EE_INVALID; } |
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191 | |||
192 | rc = segment_header(elf, &segment_hdr); |
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2928 | svoboda | 193 | if (rc != EE_OK) |
194 | return rc; |
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195 | } |
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196 | |||
197 | printf("parse sections\n"); |
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198 | |||
199 | /* Inspect all section headers and proccess them. */ |
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200 | for (i = 0; i < header->e_shnum; i++) { |
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2964 | svoboda | 201 | elf_section_header_t section_hdr; |
2928 | svoboda | 202 | |
2961 | svoboda | 203 | /* Seek to start of section header */ |
2964 | svoboda | 204 | lseek(elf->fd, header->e_shoff |
205 | + i * sizeof(elf_section_header_t), SEEK_SET); |
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2961 | svoboda | 206 | |
2964 | svoboda | 207 | rc = read(elf->fd, §ion_hdr, sizeof(elf_section_header_t)); |
208 | if (rc < 0) { printf("read error\n"); return EE_INVALID; } |
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209 | |||
210 | rc = section_header(elf, §ion_hdr); |
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2928 | svoboda | 211 | if (rc != EE_OK) |
2961 | svoboda | 212 | return rc; |
2928 | svoboda | 213 | } |
214 | |||
2964 | svoboda | 215 | elf->info->entry = |
216 | (entry_point_t)((uint8_t *)header->e_entry + elf->bias); |
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217 | |||
2928 | svoboda | 218 | printf("done\n"); |
219 | |||
220 | return EE_OK; |
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221 | } |
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222 | |||
223 | /** Print error message according to error code. |
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224 | * |
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225 | * @param rc Return code returned by elf_load(). |
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226 | * |
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227 | * @return NULL terminated description of error. |
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228 | */ |
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229 | char *elf_error(unsigned int rc) |
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230 | { |
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231 | assert(rc < sizeof(error_codes) / sizeof(char *)); |
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232 | |||
233 | return error_codes[rc]; |
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234 | } |
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235 | |||
236 | /** Process segment header. |
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237 | * |
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238 | * @param entry Segment header. |
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239 | * @param elf ELF header. |
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240 | * |
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241 | * @return EE_OK on success, error code otherwise. |
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242 | */ |
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2964 | svoboda | 243 | static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry) |
2928 | svoboda | 244 | { |
245 | switch (entry->p_type) { |
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246 | case PT_NULL: |
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247 | case PT_PHDR: |
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248 | break; |
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249 | case PT_LOAD: |
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2964 | svoboda | 250 | return load_segment(elf, entry); |
2928 | svoboda | 251 | break; |
252 | case PT_DYNAMIC: |
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253 | case PT_INTERP: |
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254 | case PT_SHLIB: |
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255 | case PT_NOTE: |
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256 | case PT_LOPROC: |
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257 | case PT_HIPROC: |
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258 | default: |
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259 | printf("segment p_type %d unknown\n", entry->p_type); |
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260 | return EE_UNSUPPORTED; |
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261 | break; |
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262 | } |
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263 | return EE_OK; |
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264 | } |
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265 | |||
266 | /** Load segment described by program header entry. |
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267 | * |
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268 | * @param entry Program header entry describing segment to be loaded. |
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269 | * @param elf ELF header. |
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270 | * |
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271 | * @return EE_OK on success, error code otherwise. |
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272 | */ |
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2964 | svoboda | 273 | int load_segment(elf_ld_t *elf, elf_segment_header_t *entry) |
2928 | svoboda | 274 | { |
275 | void *a; |
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276 | int flags = 0; |
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2932 | svoboda | 277 | uintptr_t bias; |
2928 | svoboda | 278 | int rc; |
279 | |||
280 | printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr, |
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281 | entry->p_memsz); |
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282 | |||
2964 | svoboda | 283 | bias = elf->bias; |
2928 | svoboda | 284 | |
285 | if (entry->p_align > 1) { |
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286 | if ((entry->p_offset % entry->p_align) != |
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287 | (entry->p_vaddr % entry->p_align)) { |
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288 | printf("align check 1 failed offset%%align=%d, vaddr%%align=%d\n", |
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289 | entry->p_offset % entry->p_align, |
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290 | entry->p_vaddr % entry->p_align |
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291 | ); |
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292 | return EE_INVALID; |
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293 | } |
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294 | } |
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295 | |||
296 | /* if (entry->p_flags & PF_X) |
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297 | flags |= AS_AREA_EXEC; |
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298 | if (entry->p_flags & PF_W) |
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299 | flags |= AS_AREA_WRITE; |
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300 | if (entry->p_flags & PF_R) |
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301 | flags |= AS_AREA_READ; |
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302 | flags |= AS_AREA_CACHEABLE; |
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303 | */ |
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304 | /* FIXME: Kernel won't normally allow this, unless you "patch" it */ |
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2949 | svoboda | 305 | // flags = AS_AREA_READ | AS_AREA_WRITE | AS_AREA_EXEC | AS_AREA_CACHEABLE; |
306 | flags = AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE; |
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2928 | svoboda | 307 | |
308 | /* |
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309 | * Check if the virtual address starts on page boundary. |
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310 | */ |
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311 | if (ALIGN_UP(entry->p_vaddr, PAGE_SIZE) != entry->p_vaddr) { |
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312 | printf("align check 2 failed - not page-aligned\n"); |
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313 | printf("vaddr = 0x%x, should be 0x%x\n", |
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314 | entry->p_vaddr, ALIGN_UP(entry->p_vaddr, PAGE_SIZE)); |
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315 | return EE_UNSUPPORTED; |
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316 | } |
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317 | |||
2932 | svoboda | 318 | printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias, |
319 | entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE)); |
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2928 | svoboda | 320 | |
2932 | svoboda | 321 | a = as_area_create((uint8_t *)entry->p_vaddr + bias, |
2928 | svoboda | 322 | entry->p_memsz, flags); |
323 | if (a == (void *)(-1)) { |
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324 | printf("memory mapping failed\n"); |
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325 | return EE_MEMORY; |
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326 | } |
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327 | |||
2949 | svoboda | 328 | printf("as_area_create(0x%x, 0x%x, %d) -> 0x%x\n", |
329 | entry->p_vaddr+bias, entry->p_memsz, flags, (unsigned)a); |
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2928 | svoboda | 330 | |
331 | /* |
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332 | * Load segment data |
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333 | */ |
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2949 | svoboda | 334 | printf("seek to %d\n", entry->p_offset); |
2964 | svoboda | 335 | rc = lseek(elf->fd, entry->p_offset, SEEK_SET); |
2928 | svoboda | 336 | if (rc < 0) { printf("seek error\n"); return EE_INVALID; } |
337 | |||
2949 | svoboda | 338 | printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias); |
339 | /* rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz); |
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340 | if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/ |
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341 | unsigned left, now; |
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342 | uint8_t *dp; |
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2928 | svoboda | 343 | |
2949 | svoboda | 344 | left = entry->p_filesz; |
345 | dp = (uint8_t *)(entry->p_vaddr + bias); |
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346 | |||
347 | while (left > 0) { |
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348 | now = 4096; |
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349 | if (now > left) now=left; |
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350 | printf("read %d...", now); |
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2964 | svoboda | 351 | rc = read(elf->fd, dp, now); |
2949 | svoboda | 352 | if (rc < 0) { printf("read error\n"); return EE_INVALID; } |
353 | printf("->%d\n", rc); |
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354 | left -= now; |
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355 | dp += now; |
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356 | } |
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357 | |||
2928 | svoboda | 358 | return EE_OK; |
359 | } |
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360 | |||
361 | /** Process section header. |
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362 | * |
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363 | * @param entry Segment header. |
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364 | * @param elf ELF header. |
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365 | * |
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366 | * @return EE_OK on success, error code otherwise. |
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367 | */ |
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2964 | svoboda | 368 | static int section_header(elf_ld_t *elf, elf_section_header_t *entry) |
2928 | svoboda | 369 | { |
370 | switch (entry->sh_type) { |
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371 | case SHT_PROGBITS: |
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372 | if (entry->sh_flags & SHF_TLS) { |
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373 | /* .tdata */ |
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374 | } |
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375 | break; |
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376 | case SHT_NOBITS: |
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377 | if (entry->sh_flags & SHF_TLS) { |
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378 | /* .tbss */ |
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379 | } |
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380 | break; |
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2961 | svoboda | 381 | case SHT_DYNAMIC: |
2964 | svoboda | 382 | elf->info->dynamic = |
383 | (void *)((uint8_t *)entry->sh_addr + elf->bias); |
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384 | printf("dynamic section found at 0x%x\n", |
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385 | (uintptr_t)elf->info->dynamic); |
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2961 | svoboda | 386 | break; |
2928 | svoboda | 387 | default: |
388 | break; |
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389 | } |
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390 | |||
391 | return EE_OK; |
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392 | } |
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393 | |||
394 | /** @} |
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395 | */ |