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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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3101 | svoboda | 37 | * @brief Userspace ELF loader. |
38 | * |
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39 | * This module allows loading ELF binaries (both executables and |
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40 | * shared objects) from VFS. The current implementation allocates |
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41 | * anonymous memory, fills it with segment data and then adjusts |
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42 | * the memory areas' flags to the final value. In the future, |
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43 | * the segments will be mapped directly from the file. |
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2928 | svoboda | 44 | */ |
45 | |||
46 | #include <stdio.h> |
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47 | #include <sys/types.h> |
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48 | #include <align.h> |
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49 | #include <assert.h> |
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50 | #include <as.h> |
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2962 | svoboda | 51 | #include <unistd.h> |
52 | #include <fcntl.h> |
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53 | |||
2928 | svoboda | 54 | #include "elf.h" |
2962 | svoboda | 55 | #include "pcb.h" |
56 | #include "elf_load.h" |
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3131 | svoboda | 57 | #include "arch.h" |
2928 | svoboda | 58 | |
59 | static char *error_codes[] = { |
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60 | "no error", |
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61 | "invalid image", |
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62 | "address space error", |
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63 | "incompatible image", |
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64 | "unsupported image type", |
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65 | "irrecoverable error" |
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66 | }; |
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67 | |||
2972 | svoboda | 68 | static unsigned int elf_load(elf_ld_t *elf, size_t so_bias); |
2964 | svoboda | 69 | static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry); |
70 | static int section_header(elf_ld_t *elf, elf_section_header_t *entry); |
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71 | static int load_segment(elf_ld_t *elf, elf_segment_header_t *entry); |
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2928 | svoboda | 72 | |
3101 | svoboda | 73 | /** Load ELF binary from a file. |
74 | * |
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75 | * Load an ELF binary from the specified file. If the file is |
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76 | * an executable program, it is loaded unbiased. If it is a shared |
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77 | * object, it is loaded with the bias @a so_bias. Some information |
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78 | * extracted from the binary is stored in a elf_info_t structure |
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79 | * pointed to by @a info. |
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80 | * |
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81 | * @param file_name Path to the ELF file. |
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82 | * @param so_bias Bias to use if the file is a shared object. |
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83 | * @param info Pointer to a structure for storing information |
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84 | * extracted from the binary. |
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85 | * |
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86 | * @return EOK on success or negative error code. |
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87 | */ |
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2972 | svoboda | 88 | int elf_load_file(char *file_name, size_t so_bias, elf_info_t *info) |
2964 | svoboda | 89 | { |
90 | elf_ld_t elf; |
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2928 | svoboda | 91 | |
2962 | svoboda | 92 | int fd; |
93 | int rc; |
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94 | |||
95 | printf("open and read '%s'...\n", file_name); |
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96 | |||
3101 | svoboda | 97 | fd = open(file_name, O_RDONLY); |
2962 | svoboda | 98 | if (fd < 0) { |
99 | printf("failed opening file\n"); |
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100 | return -1; |
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101 | } |
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102 | |||
2964 | svoboda | 103 | elf.fd = fd; |
104 | elf.info = info; |
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105 | |||
2972 | svoboda | 106 | rc = elf_load(&elf, so_bias); |
2962 | svoboda | 107 | printf("elf_load() -> %d\n", rc); |
108 | |||
109 | close(fd); |
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110 | |||
111 | return rc; |
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112 | } |
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113 | |||
3101 | svoboda | 114 | /** Run an ELF executable. |
115 | * |
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116 | * Transfers control to the entry point of an ELF executable loaded |
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117 | * earlier with elf_load_file(). This function does not return. |
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118 | * |
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119 | * @param info Info structure filled earlier by elf_load_file() |
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120 | */ |
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2964 | svoboda | 121 | void elf_run(elf_info_t *info) |
2962 | svoboda | 122 | { |
3129 | svoboda | 123 | printf("entry point: 0x%llx\n", info->entry); |
3131 | svoboda | 124 | //(*info->entry)(); |
125 | program_run(info->entry); |
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2962 | svoboda | 126 | |
127 | /* not reached */ |
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128 | } |
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129 | |||
3101 | svoboda | 130 | /** Create the program control block (PCB). |
131 | * |
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132 | * Create and install the program control block, initialising it |
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133 | * with program information from @a info. |
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134 | * |
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135 | * @param info Program info structure |
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136 | * @return EOK on success or negative error code |
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137 | */ |
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2964 | svoboda | 138 | int elf_create_pcb(elf_info_t *info) |
2962 | svoboda | 139 | { |
140 | pcb_t *pcb; |
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141 | void *a; |
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142 | |||
2990 | svoboda | 143 | pcb = __pcb_get(); |
2962 | svoboda | 144 | |
145 | a = as_area_create(pcb, sizeof(pcb_t), AS_AREA_READ | AS_AREA_WRITE); |
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146 | if (a == (void *)(-1)) { |
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147 | printf("elf_create_pcb: memory mapping failed\n"); |
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148 | return EE_MEMORY; |
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149 | } |
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150 | |||
2964 | svoboda | 151 | pcb->entry = info->entry; |
2965 | svoboda | 152 | pcb->dynamic = info->dynamic; |
2962 | svoboda | 153 | |
154 | return 0; |
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155 | } |
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156 | |||
157 | |||
3101 | svoboda | 158 | /** Load an ELF binary. |
2928 | svoboda | 159 | * |
3101 | svoboda | 160 | * The @a elf structure contains the loader state, including |
161 | * an open file, from which the binary will be loaded, |
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162 | * a pointer to the @c info structure etc. |
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163 | * |
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164 | * @param elf Pointer to loader state buffer. |
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165 | * @param so_bias Bias to use if the file is a shared object. |
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166 | * @return EE_OK on success or EE_xx error code. |
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2928 | svoboda | 167 | */ |
2972 | svoboda | 168 | static unsigned int elf_load(elf_ld_t *elf, size_t so_bias) |
2928 | svoboda | 169 | { |
2964 | svoboda | 170 | elf_header_t header_buf; |
171 | elf_header_t *header = &header_buf; |
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2928 | svoboda | 172 | int i, rc; |
173 | |||
2964 | svoboda | 174 | rc = read(elf->fd, header, sizeof(elf_header_t)); |
2928 | svoboda | 175 | if (rc < 0) { |
176 | printf("read error\n"); |
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177 | return EE_INVALID; |
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178 | } |
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179 | |||
2964 | svoboda | 180 | elf->header = header; |
181 | |||
2928 | svoboda | 182 | printf("ELF-load:"); |
183 | /* Identify ELF */ |
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184 | if (header->e_ident[EI_MAG0] != ELFMAG0 || |
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185 | header->e_ident[EI_MAG1] != ELFMAG1 || |
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186 | header->e_ident[EI_MAG2] != ELFMAG2 || |
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187 | header->e_ident[EI_MAG3] != ELFMAG3) { |
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188 | printf("invalid header\n"); |
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189 | return EE_INVALID; |
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190 | } |
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191 | |||
192 | /* Identify ELF compatibility */ |
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193 | if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING || |
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194 | header->e_machine != ELF_MACHINE || |
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195 | header->e_ident[EI_VERSION] != EV_CURRENT || |
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196 | header->e_version != EV_CURRENT || |
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197 | header->e_ident[EI_CLASS] != ELF_CLASS) { |
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198 | printf("incompatible data/version/class\n"); |
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199 | return EE_INCOMPATIBLE; |
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200 | } |
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201 | |||
2992 | svoboda | 202 | if (header->e_phentsize != sizeof(elf_segment_header_t)) { |
203 | printf("e_phentsize:%d != %d\n", header->e_phentsize, |
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204 | sizeof(elf_segment_header_t)); |
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2928 | svoboda | 205 | return EE_INCOMPATIBLE; |
2992 | svoboda | 206 | } |
2928 | svoboda | 207 | |
2992 | svoboda | 208 | if (header->e_shentsize != sizeof(elf_section_header_t)) { |
209 | printf("e_shentsize:%d != %d\n", header->e_shentsize, |
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210 | sizeof(elf_section_header_t)); |
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2928 | svoboda | 211 | return EE_INCOMPATIBLE; |
2992 | svoboda | 212 | } |
2928 | svoboda | 213 | |
214 | /* Check if the object type is supported. */ |
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215 | if (header->e_type != ET_EXEC && header->e_type != ET_DYN) { |
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216 | printf("Object type %d is not supported\n", header->e_type); |
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217 | return EE_UNSUPPORTED; |
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218 | } |
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219 | |||
2972 | svoboda | 220 | /* Shared objects can be loaded with a bias */ |
2971 | svoboda | 221 | printf("Object type: %d\n", header->e_type); |
2964 | svoboda | 222 | if (header->e_type == ET_DYN) |
2972 | svoboda | 223 | elf->bias = so_bias; |
2964 | svoboda | 224 | else |
225 | elf->bias = 0; |
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226 | |||
2972 | svoboda | 227 | printf("Bias set to 0x%x\n", elf->bias); |
3004 | svoboda | 228 | elf->info->interp = NULL; |
229 | elf->info->dynamic = NULL; |
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2971 | svoboda | 230 | |
2928 | svoboda | 231 | printf("parse segments\n"); |
232 | |||
233 | /* Walk through all segment headers and process them. */ |
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234 | for (i = 0; i < header->e_phnum; i++) { |
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2964 | svoboda | 235 | elf_segment_header_t segment_hdr; |
2928 | svoboda | 236 | |
2961 | svoboda | 237 | /* Seek to start of segment header */ |
2964 | svoboda | 238 | lseek(elf->fd, header->e_phoff |
239 | + i * sizeof(elf_segment_header_t), SEEK_SET); |
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2928 | svoboda | 240 | |
2964 | svoboda | 241 | rc = read(elf->fd, &segment_hdr, sizeof(elf_segment_header_t)); |
242 | if (rc < 0) { printf("read error\n"); return EE_INVALID; } |
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243 | |||
244 | rc = segment_header(elf, &segment_hdr); |
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2928 | svoboda | 245 | if (rc != EE_OK) |
246 | return rc; |
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247 | } |
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248 | |||
249 | printf("parse sections\n"); |
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250 | |||
251 | /* Inspect all section headers and proccess them. */ |
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252 | for (i = 0; i < header->e_shnum; i++) { |
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2964 | svoboda | 253 | elf_section_header_t section_hdr; |
2928 | svoboda | 254 | |
2961 | svoboda | 255 | /* Seek to start of section header */ |
2964 | svoboda | 256 | lseek(elf->fd, header->e_shoff |
257 | + i * sizeof(elf_section_header_t), SEEK_SET); |
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2961 | svoboda | 258 | |
2964 | svoboda | 259 | rc = read(elf->fd, §ion_hdr, sizeof(elf_section_header_t)); |
260 | if (rc < 0) { printf("read error\n"); return EE_INVALID; } |
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261 | |||
262 | rc = section_header(elf, §ion_hdr); |
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2928 | svoboda | 263 | if (rc != EE_OK) |
2961 | svoboda | 264 | return rc; |
2928 | svoboda | 265 | } |
266 | |||
2964 | svoboda | 267 | elf->info->entry = |
268 | (entry_point_t)((uint8_t *)header->e_entry + elf->bias); |
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269 | |||
2928 | svoboda | 270 | printf("done\n"); |
271 | |||
272 | return EE_OK; |
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273 | } |
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274 | |||
275 | /** Print error message according to error code. |
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276 | * |
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277 | * @param rc Return code returned by elf_load(). |
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278 | * |
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279 | * @return NULL terminated description of error. |
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280 | */ |
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281 | char *elf_error(unsigned int rc) |
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282 | { |
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283 | assert(rc < sizeof(error_codes) / sizeof(char *)); |
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284 | |||
285 | return error_codes[rc]; |
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286 | } |
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287 | |||
288 | /** Process segment header. |
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289 | * |
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3101 | svoboda | 290 | * @param entry Segment header. |
2928 | svoboda | 291 | * |
292 | * @return EE_OK on success, error code otherwise. |
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293 | */ |
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2964 | svoboda | 294 | static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry) |
2928 | svoboda | 295 | { |
296 | switch (entry->p_type) { |
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297 | case PT_NULL: |
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298 | case PT_PHDR: |
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299 | break; |
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300 | case PT_LOAD: |
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2964 | svoboda | 301 | return load_segment(elf, entry); |
2928 | svoboda | 302 | break; |
3004 | svoboda | 303 | case PT_INTERP: |
304 | /* Assume silently interp == "/rtld.so" */ |
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305 | elf->info->interp = "/rtld.so"; |
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306 | break; |
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2928 | svoboda | 307 | case PT_DYNAMIC: |
308 | case PT_SHLIB: |
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309 | case PT_NOTE: |
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310 | case PT_LOPROC: |
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311 | case PT_HIPROC: |
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312 | default: |
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313 | printf("segment p_type %d unknown\n", entry->p_type); |
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314 | return EE_UNSUPPORTED; |
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315 | break; |
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316 | } |
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317 | return EE_OK; |
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318 | } |
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319 | |||
320 | /** Load segment described by program header entry. |
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321 | * |
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3101 | svoboda | 322 | * @param elf Loader state. |
2928 | svoboda | 323 | * @param entry Program header entry describing segment to be loaded. |
324 | * |
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325 | * @return EE_OK on success, error code otherwise. |
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326 | */ |
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2964 | svoboda | 327 | int load_segment(elf_ld_t *elf, elf_segment_header_t *entry) |
2928 | svoboda | 328 | { |
329 | void *a; |
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330 | int flags = 0; |
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2932 | svoboda | 331 | uintptr_t bias; |
3010 | svoboda | 332 | uintptr_t base; |
333 | size_t mem_sz; |
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2928 | svoboda | 334 | int rc; |
335 | |||
336 | printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr, |
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337 | entry->p_memsz); |
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338 | |||
2964 | svoboda | 339 | bias = elf->bias; |
2928 | svoboda | 340 | |
341 | if (entry->p_align > 1) { |
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342 | if ((entry->p_offset % entry->p_align) != |
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343 | (entry->p_vaddr % entry->p_align)) { |
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344 | printf("align check 1 failed offset%%align=%d, vaddr%%align=%d\n", |
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345 | entry->p_offset % entry->p_align, |
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346 | entry->p_vaddr % entry->p_align |
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347 | ); |
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348 | return EE_INVALID; |
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349 | } |
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350 | } |
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351 | |||
2992 | svoboda | 352 | /* Final flags that will be set for the memory area */ |
353 | |||
2985 | svoboda | 354 | if (entry->p_flags & PF_X) |
2928 | svoboda | 355 | flags |= AS_AREA_EXEC; |
356 | if (entry->p_flags & PF_W) |
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357 | flags |= AS_AREA_WRITE; |
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358 | if (entry->p_flags & PF_R) |
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359 | flags |= AS_AREA_READ; |
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360 | flags |= AS_AREA_CACHEABLE; |
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3010 | svoboda | 361 | |
362 | base = ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE); |
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363 | mem_sz = entry->p_memsz + (entry->p_vaddr - base); |
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2985 | svoboda | 364 | |
2932 | svoboda | 365 | printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias, |
366 | entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE)); |
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2928 | svoboda | 367 | |
2985 | svoboda | 368 | /* |
369 | * For the course of loading, the area needs to be readable |
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370 | * and writeable. |
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371 | */ |
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3010 | svoboda | 372 | a = as_area_create((uint8_t *)base + bias, |
373 | mem_sz, AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE); |
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2928 | svoboda | 374 | if (a == (void *)(-1)) { |
375 | printf("memory mapping failed\n"); |
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376 | return EE_MEMORY; |
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377 | } |
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378 | |||
2992 | svoboda | 379 | printf("as_area_create(0x%lx, 0x%x, %d) -> 0x%lx\n", |
380 | entry->p_vaddr+bias, entry->p_memsz, flags, (uintptr_t)a); |
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2928 | svoboda | 381 | |
382 | /* |
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383 | * Load segment data |
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384 | */ |
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2949 | svoboda | 385 | printf("seek to %d\n", entry->p_offset); |
2964 | svoboda | 386 | rc = lseek(elf->fd, entry->p_offset, SEEK_SET); |
2928 | svoboda | 387 | if (rc < 0) { printf("seek error\n"); return EE_INVALID; } |
388 | |||
2949 | svoboda | 389 | printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias); |
390 | /* rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz); |
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391 | if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/ |
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3101 | svoboda | 392 | |
393 | /* Long reads are not possible yet. Load segment picewise */ |
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394 | |||
2949 | svoboda | 395 | unsigned left, now; |
396 | uint8_t *dp; |
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2928 | svoboda | 397 | |
2949 | svoboda | 398 | left = entry->p_filesz; |
399 | dp = (uint8_t *)(entry->p_vaddr + bias); |
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400 | |||
401 | while (left > 0) { |
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2977 | svoboda | 402 | now = 16384; |
3101 | svoboda | 403 | if (now > left) now = left; |
404 | |||
2949 | svoboda | 405 | printf("read %d...", now); |
2964 | svoboda | 406 | rc = read(elf->fd, dp, now); |
3101 | svoboda | 407 | printf("->%d\n", rc); |
408 | |||
2949 | svoboda | 409 | if (rc < 0) { printf("read error\n"); return EE_INVALID; } |
3101 | svoboda | 410 | |
2949 | svoboda | 411 | left -= now; |
412 | dp += now; |
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413 | } |
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414 | |||
2985 | svoboda | 415 | printf("set area flags to %d\n", flags); |
416 | rc = as_area_change_flags((uint8_t *)entry->p_vaddr + bias, flags); |
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417 | if (rc != 0) { |
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418 | printf("failed to set memory area flags\n"); |
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419 | return EE_MEMORY; |
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420 | } |
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421 | |||
2928 | svoboda | 422 | return EE_OK; |
423 | } |
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424 | |||
425 | /** Process section header. |
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426 | * |
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3101 | svoboda | 427 | * @param elf Loader state. |
2928 | svoboda | 428 | * @param entry Segment header. |
429 | * |
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430 | * @return EE_OK on success, error code otherwise. |
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431 | */ |
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2964 | svoboda | 432 | static int section_header(elf_ld_t *elf, elf_section_header_t *entry) |
2928 | svoboda | 433 | { |
434 | switch (entry->sh_type) { |
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435 | case SHT_PROGBITS: |
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436 | if (entry->sh_flags & SHF_TLS) { |
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437 | /* .tdata */ |
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438 | } |
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439 | break; |
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440 | case SHT_NOBITS: |
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441 | if (entry->sh_flags & SHF_TLS) { |
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442 | /* .tbss */ |
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443 | } |
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444 | break; |
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2961 | svoboda | 445 | case SHT_DYNAMIC: |
3101 | svoboda | 446 | /* Record pointer to dynamic section into info structure */ |
2964 | svoboda | 447 | elf->info->dynamic = |
448 | (void *)((uint8_t *)entry->sh_addr + elf->bias); |
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449 | printf("dynamic section found at 0x%x\n", |
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450 | (uintptr_t)elf->info->dynamic); |
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2961 | svoboda | 451 | break; |
2928 | svoboda | 452 | default: |
453 | break; |
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454 | } |
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455 | |||
456 | return EE_OK; |
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457 | } |
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458 | |||
459 | /** @} |
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460 | */ |