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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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3210 | svoboda | 53 | #include <smc.h> |
3160 | svoboda | 54 | #include <loader/pcb.h> |
2962 | svoboda | 55 | |
2928 | svoboda | 56 | #include "elf.h" |
2962 | svoboda | 57 | #include "elf_load.h" |
3131 | svoboda | 58 | #include "arch.h" |
2928 | svoboda | 59 | |
60 | static char *error_codes[] = { |
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61 | "no error", |
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62 | "invalid image", |
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63 | "address space error", |
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64 | "incompatible image", |
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65 | "unsupported image type", |
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66 | "irrecoverable error" |
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67 | }; |
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68 | |||
2972 | svoboda | 69 | static unsigned int elf_load(elf_ld_t *elf, size_t so_bias); |
2964 | svoboda | 70 | static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry); |
71 | static int section_header(elf_ld_t *elf, elf_section_header_t *entry); |
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72 | static int load_segment(elf_ld_t *elf, elf_segment_header_t *entry); |
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2928 | svoboda | 73 | |
3403 | svoboda | 74 | /** Read until the buffer is read in its entirety. */ |
75 | static int my_read(int fd, char *buf, size_t len) |
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76 | { |
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77 | int cnt = 0; |
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78 | do { |
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79 | buf += cnt; |
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80 | len -= cnt; |
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81 | cnt = read(fd, buf, len); |
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82 | } while ((cnt > 0) && ((len - cnt) > 0)); |
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83 | |||
84 | return cnt; |
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85 | } |
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86 | |||
3101 | svoboda | 87 | /** Load ELF binary from a file. |
88 | * |
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89 | * Load an ELF binary from the specified file. If the file is |
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90 | * an executable program, it is loaded unbiased. If it is a shared |
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91 | * object, it is loaded with the bias @a so_bias. Some information |
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92 | * extracted from the binary is stored in a elf_info_t structure |
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93 | * pointed to by @a info. |
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94 | * |
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95 | * @param file_name Path to the ELF file. |
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96 | * @param so_bias Bias to use if the file is a shared object. |
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97 | * @param info Pointer to a structure for storing information |
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98 | * extracted from the binary. |
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99 | * |
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100 | * @return EOK on success or negative error code. |
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101 | */ |
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3552 | svoboda | 102 | int elf_load_file(char *file_name, size_t so_bias, eld_flags_t flags, |
103 | elf_info_t *info) |
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2964 | svoboda | 104 | { |
105 | elf_ld_t elf; |
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2928 | svoboda | 106 | |
2962 | svoboda | 107 | int fd; |
108 | int rc; |
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109 | |||
3155 | svoboda | 110 | // printf("open and read '%s'...\n", file_name); |
2962 | svoboda | 111 | |
3101 | svoboda | 112 | fd = open(file_name, O_RDONLY); |
2962 | svoboda | 113 | if (fd < 0) { |
3400 | svoboda | 114 | printf("failed opening file (error %d)\n", fd); |
2962 | svoboda | 115 | return -1; |
116 | } |
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117 | |||
2964 | svoboda | 118 | elf.fd = fd; |
119 | elf.info = info; |
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3552 | svoboda | 120 | elf.flags = flags; |
2964 | svoboda | 121 | |
2972 | svoboda | 122 | rc = elf_load(&elf, so_bias); |
2962 | svoboda | 123 | |
124 | close(fd); |
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125 | |||
126 | return rc; |
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127 | } |
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128 | |||
3101 | svoboda | 129 | /** Run an ELF executable. |
130 | * |
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131 | * Transfers control to the entry point of an ELF executable loaded |
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132 | * earlier with elf_load_file(). This function does not return. |
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133 | * |
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134 | * @param info Info structure filled earlier by elf_load_file() |
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135 | */ |
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3170 | svoboda | 136 | void elf_run(elf_info_t *info, pcb_t *pcb) |
2962 | svoboda | 137 | { |
3169 | svoboda | 138 | program_run(info->entry, pcb); |
2962 | svoboda | 139 | |
140 | /* not reached */ |
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141 | } |
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142 | |||
3101 | svoboda | 143 | /** Create the program control block (PCB). |
144 | * |
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3170 | svoboda | 145 | * Fills the program control block @a pcb with information from |
146 | * @a info. |
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3101 | svoboda | 147 | * |
148 | * @param info Program info structure |
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149 | * @return EOK on success or negative error code |
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150 | */ |
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3170 | svoboda | 151 | void elf_create_pcb(elf_info_t *info, pcb_t *pcb) |
2962 | svoboda | 152 | { |
2964 | svoboda | 153 | pcb->entry = info->entry; |
2965 | svoboda | 154 | pcb->dynamic = info->dynamic; |
2962 | svoboda | 155 | } |
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 | |||
3403 | svoboda | 174 | rc = my_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 | |||
3155 | svoboda | 182 | // printf("ELF-load:"); |
2928 | svoboda | 183 | /* Identify ELF */ |
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 */ |
3155 | 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 | |||
3155 | 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 | |
3155 | svoboda | 231 | // printf("parse segments\n"); |
2928 | svoboda | 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 | |
3403 | svoboda | 241 | rc = my_read(elf->fd, &segment_hdr, |
242 | sizeof(elf_segment_header_t)); |
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243 | if (rc < 0) { |
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244 | printf("read error\n"); |
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245 | return EE_INVALID; |
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246 | } |
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2964 | svoboda | 247 | |
248 | rc = segment_header(elf, &segment_hdr); |
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2928 | svoboda | 249 | if (rc != EE_OK) |
250 | return rc; |
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251 | } |
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252 | |||
3155 | svoboda | 253 | // printf("parse sections\n"); |
2928 | svoboda | 254 | |
255 | /* Inspect all section headers and proccess them. */ |
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256 | for (i = 0; i < header->e_shnum; i++) { |
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2964 | svoboda | 257 | elf_section_header_t section_hdr; |
2928 | svoboda | 258 | |
2961 | svoboda | 259 | /* Seek to start of section header */ |
2964 | svoboda | 260 | lseek(elf->fd, header->e_shoff |
261 | + i * sizeof(elf_section_header_t), SEEK_SET); |
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2961 | svoboda | 262 | |
3403 | svoboda | 263 | rc = my_read(elf->fd, §ion_hdr, |
264 | sizeof(elf_section_header_t)); |
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265 | if (rc < 0) { |
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266 | printf("read error\n"); |
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267 | return EE_INVALID; |
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268 | } |
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2964 | svoboda | 269 | |
270 | rc = section_header(elf, §ion_hdr); |
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2928 | svoboda | 271 | if (rc != EE_OK) |
2961 | svoboda | 272 | return rc; |
2928 | svoboda | 273 | } |
274 | |||
2964 | svoboda | 275 | elf->info->entry = |
276 | (entry_point_t)((uint8_t *)header->e_entry + elf->bias); |
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277 | |||
3155 | svoboda | 278 | // printf("done\n"); |
2928 | svoboda | 279 | |
280 | return EE_OK; |
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281 | } |
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282 | |||
283 | /** Print error message according to error code. |
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284 | * |
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285 | * @param rc Return code returned by elf_load(). |
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286 | * |
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287 | * @return NULL terminated description of error. |
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288 | */ |
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289 | char *elf_error(unsigned int rc) |
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290 | { |
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291 | assert(rc < sizeof(error_codes) / sizeof(char *)); |
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292 | |||
293 | return error_codes[rc]; |
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294 | } |
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295 | |||
296 | /** Process segment header. |
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297 | * |
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3101 | svoboda | 298 | * @param entry Segment header. |
2928 | svoboda | 299 | * |
300 | * @return EE_OK on success, error code otherwise. |
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301 | */ |
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2964 | svoboda | 302 | static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry) |
2928 | svoboda | 303 | { |
304 | switch (entry->p_type) { |
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305 | case PT_NULL: |
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306 | case PT_PHDR: |
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307 | break; |
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308 | case PT_LOAD: |
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2964 | svoboda | 309 | return load_segment(elf, entry); |
2928 | svoboda | 310 | break; |
3004 | svoboda | 311 | case PT_INTERP: |
3552 | svoboda | 312 | /* Assume silently interp == "/lib/rtld" */ |
313 | elf->info->interp = "/lib/rtld"; |
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3004 | svoboda | 314 | break; |
2928 | svoboda | 315 | case PT_DYNAMIC: |
316 | case PT_SHLIB: |
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317 | case PT_NOTE: |
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318 | case PT_LOPROC: |
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319 | case PT_HIPROC: |
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320 | default: |
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321 | printf("segment p_type %d unknown\n", entry->p_type); |
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322 | return EE_UNSUPPORTED; |
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323 | break; |
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324 | } |
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325 | return EE_OK; |
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326 | } |
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327 | |||
328 | /** Load segment described by program header entry. |
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329 | * |
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3101 | svoboda | 330 | * @param elf Loader state. |
2928 | svoboda | 331 | * @param entry Program header entry describing segment to be loaded. |
332 | * |
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333 | * @return EE_OK on success, error code otherwise. |
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334 | */ |
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2964 | svoboda | 335 | int load_segment(elf_ld_t *elf, elf_segment_header_t *entry) |
2928 | svoboda | 336 | { |
337 | void *a; |
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338 | int flags = 0; |
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2932 | svoboda | 339 | uintptr_t bias; |
3010 | svoboda | 340 | uintptr_t base; |
341 | size_t mem_sz; |
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2928 | svoboda | 342 | int rc; |
343 | |||
3155 | svoboda | 344 | // printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr, |
345 | // entry->p_memsz); |
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2928 | svoboda | 346 | |
2964 | svoboda | 347 | bias = elf->bias; |
2928 | svoboda | 348 | |
349 | if (entry->p_align > 1) { |
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350 | if ((entry->p_offset % entry->p_align) != |
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351 | (entry->p_vaddr % entry->p_align)) { |
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3403 | svoboda | 352 | printf("align check 1 failed offset%%align=%d, " |
353 | "vaddr%%align=%d\n", |
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354 | entry->p_offset % entry->p_align, |
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355 | entry->p_vaddr % entry->p_align |
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2928 | svoboda | 356 | ); |
357 | return EE_INVALID; |
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358 | } |
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359 | } |
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360 | |||
2992 | svoboda | 361 | /* Final flags that will be set for the memory area */ |
362 | |||
2985 | svoboda | 363 | if (entry->p_flags & PF_X) |
2928 | svoboda | 364 | flags |= AS_AREA_EXEC; |
365 | if (entry->p_flags & PF_W) |
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366 | flags |= AS_AREA_WRITE; |
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367 | if (entry->p_flags & PF_R) |
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368 | flags |= AS_AREA_READ; |
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369 | flags |= AS_AREA_CACHEABLE; |
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3010 | svoboda | 370 | |
371 | base = ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE); |
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372 | mem_sz = entry->p_memsz + (entry->p_vaddr - base); |
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2985 | svoboda | 373 | |
3155 | svoboda | 374 | // printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias, |
375 | // entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE)); |
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2928 | svoboda | 376 | |
2985 | svoboda | 377 | /* |
378 | * For the course of loading, the area needs to be readable |
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379 | * and writeable. |
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380 | */ |
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3403 | svoboda | 381 | a = as_area_create((uint8_t *)base + bias, mem_sz, |
382 | AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE); |
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2928 | svoboda | 383 | if (a == (void *)(-1)) { |
384 | printf("memory mapping failed\n"); |
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385 | return EE_MEMORY; |
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386 | } |
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387 | |||
3155 | svoboda | 388 | // printf("as_area_create(0x%lx, 0x%x, %d) -> 0x%lx\n", |
389 | // entry->p_vaddr+bias, entry->p_memsz, flags, (uintptr_t)a); |
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2928 | svoboda | 390 | |
391 | /* |
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392 | * Load segment data |
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393 | */ |
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3155 | svoboda | 394 | // printf("seek to %d\n", entry->p_offset); |
2964 | svoboda | 395 | rc = lseek(elf->fd, entry->p_offset, SEEK_SET); |
3403 | svoboda | 396 | if (rc < 0) { |
397 | printf("seek error\n"); |
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398 | return EE_INVALID; |
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399 | } |
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2928 | svoboda | 400 | |
3155 | svoboda | 401 | // printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias); |
2949 | svoboda | 402 | /* rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz); |
403 | if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/ |
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3101 | svoboda | 404 | |
405 | /* Long reads are not possible yet. Load segment picewise */ |
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406 | |||
2949 | svoboda | 407 | unsigned left, now; |
408 | uint8_t *dp; |
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2928 | svoboda | 409 | |
2949 | svoboda | 410 | left = entry->p_filesz; |
411 | dp = (uint8_t *)(entry->p_vaddr + bias); |
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412 | |||
413 | while (left > 0) { |
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2977 | svoboda | 414 | now = 16384; |
3101 | svoboda | 415 | if (now > left) now = left; |
416 | |||
3155 | svoboda | 417 | // printf("read %d...", now); |
3403 | svoboda | 418 | rc = my_read(elf->fd, dp, now); |
3155 | svoboda | 419 | // printf("->%d\n", rc); |
3101 | svoboda | 420 | |
3403 | svoboda | 421 | if (rc < 0) { |
422 | printf("read error\n"); |
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423 | return EE_INVALID; |
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424 | } |
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3101 | svoboda | 425 | |
2949 | svoboda | 426 | left -= now; |
427 | dp += now; |
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428 | } |
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429 | |||
3552 | svoboda | 430 | /* |
431 | * The caller wants to modify the segments first. He will then |
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432 | * need to set the right access mode and ensure SMC coherence. |
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433 | */ |
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434 | if ((elf->flags & ELDF_RW) != 0) return EE_OK; |
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435 | |||
3562 | svoboda | 436 | // printf("set area flags to %d\n", flags); |
2985 | svoboda | 437 | rc = as_area_change_flags((uint8_t *)entry->p_vaddr + bias, flags); |
438 | if (rc != 0) { |
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439 | printf("failed to set memory area flags\n"); |
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440 | return EE_MEMORY; |
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441 | } |
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442 | |||
3210 | svoboda | 443 | if (flags & AS_AREA_EXEC) { |
444 | /* Enforce SMC coherence for the segment */ |
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445 | if (smc_coherence(entry->p_vaddr + bias, entry->p_filesz)) |
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446 | return EE_MEMORY; |
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447 | } |
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448 | |||
2928 | svoboda | 449 | return EE_OK; |
450 | } |
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451 | |||
452 | /** Process section header. |
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453 | * |
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3101 | svoboda | 454 | * @param elf Loader state. |
2928 | svoboda | 455 | * @param entry Segment header. |
456 | * |
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457 | * @return EE_OK on success, error code otherwise. |
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458 | */ |
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2964 | svoboda | 459 | static int section_header(elf_ld_t *elf, elf_section_header_t *entry) |
2928 | svoboda | 460 | { |
461 | switch (entry->sh_type) { |
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462 | case SHT_PROGBITS: |
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463 | if (entry->sh_flags & SHF_TLS) { |
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464 | /* .tdata */ |
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465 | } |
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466 | break; |
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467 | case SHT_NOBITS: |
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468 | if (entry->sh_flags & SHF_TLS) { |
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469 | /* .tbss */ |
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470 | } |
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471 | break; |
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2961 | svoboda | 472 | case SHT_DYNAMIC: |
3101 | svoboda | 473 | /* Record pointer to dynamic section into info structure */ |
2964 | svoboda | 474 | elf->info->dynamic = |
475 | (void *)((uint8_t *)entry->sh_addr + elf->bias); |
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476 | printf("dynamic section found at 0x%x\n", |
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477 | (uintptr_t)elf->info->dynamic); |
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2961 | svoboda | 478 | break; |
2928 | svoboda | 479 | default: |
480 | break; |
||
481 | } |
||
482 | |||
483 | return EE_OK; |
||
484 | } |
||
485 | |||
486 | /** @} |
||
487 | */ |