[292] | 1 | /** |
---|
[425] | 2 | * \file : boot_elf_loader.c |
---|
[292] | 3 | * \date : August 2012 |
---|
| 4 | * \author : Cesar Fuguet |
---|
| 5 | * |
---|
| 6 | * This file defines an elf file loader which reads an executable elf file |
---|
| 7 | * starting at a sector passed as argument of a disk and copy the different |
---|
| 8 | * ELF program segments in the appropriate memory address using as information |
---|
| 9 | * the virtual address read from the elf file. |
---|
| 10 | */ |
---|
| 11 | |
---|
| 12 | #include <boot_ioc.h> |
---|
| 13 | #include <elf-types.h> |
---|
| 14 | #include <boot_tty.h> |
---|
[425] | 15 | #include <boot_utils.h> |
---|
[292] | 16 | #include <defs.h> |
---|
| 17 | |
---|
[425] | 18 | #if (BOOT_DEBUG == 1) |
---|
| 19 | static char* init_state_str[] = { |
---|
| 20 | "ELF_HEADER_STATE", |
---|
| 21 | "ELF_PROGRAM_HEADER_STATE", |
---|
| 22 | "ELF_OFFSET_STATE", |
---|
| 23 | "ELF_SEGMENT_STATE", |
---|
| 24 | "ELF_END_STATE" |
---|
| 25 | }; |
---|
| 26 | #endif |
---|
| 27 | |
---|
[292] | 28 | void * boot_elf_loader(unsigned int lba) |
---|
| 29 | { |
---|
[425] | 30 | /* |
---|
[292] | 31 | * Temporary variables used by the boot loader |
---|
| 32 | */ |
---|
| 33 | unsigned char boot_elf_loader_buffer[512]; |
---|
| 34 | Elf32_Ehdr elf_header; |
---|
| 35 | Elf32_Phdr elf_pht[PHDR_ARRAY_SIZE]; |
---|
| 36 | |
---|
| 37 | unsigned char * buffer_ptr; |
---|
[425] | 38 | Elf32_Ehdr * elf_ehdr_ptr; |
---|
| 39 | Elf32_Phdr * elf_phdr_ptr; |
---|
[292] | 40 | |
---|
| 41 | unsigned int nb_available; |
---|
| 42 | unsigned int nb_rest; |
---|
| 43 | unsigned int nb_read; |
---|
| 44 | unsigned int nb_block; |
---|
| 45 | unsigned int offset; |
---|
[425] | 46 | |
---|
| 47 | unsigned char * pseg_ptr; |
---|
| 48 | unsigned int pseg_start; |
---|
| 49 | unsigned int pseg_end; |
---|
| 50 | unsigned int pseg_remainder; |
---|
[292] | 51 | unsigned int pseg; |
---|
[412] | 52 | |
---|
[292] | 53 | /* |
---|
| 54 | * Loader state machine definition |
---|
[412] | 55 | */ |
---|
[425] | 56 | typedef enum |
---|
[292] | 57 | { |
---|
| 58 | ELF_HEADER_STATE, |
---|
| 59 | ELF_PROGRAM_HEADER_STATE, |
---|
| 60 | ELF_OFFSET_STATE, |
---|
| 61 | ELF_SEGMENT_STATE, |
---|
| 62 | ELF_END_STATE |
---|
[425] | 63 | } elf_loader_t; |
---|
[292] | 64 | |
---|
[425] | 65 | elf_loader_t init_state; |
---|
| 66 | init_state = ELF_HEADER_STATE; |
---|
| 67 | |
---|
[412] | 68 | #if (BOOT_DEBUG == 1) |
---|
[425] | 69 | elf_loader_t init_state_debug; |
---|
| 70 | init_state_debug = ELF_END_STATE; |
---|
[412] | 71 | #endif |
---|
| 72 | |
---|
[292] | 73 | boot_puts("Starting boot_elf_loader function...\n\r"); |
---|
| 74 | |
---|
[425] | 75 | nb_block = lba; |
---|
| 76 | nb_available = 0; |
---|
| 77 | nb_rest = sizeof(Elf32_Ehdr); |
---|
| 78 | pseg = 0; |
---|
| 79 | offset = 0; |
---|
| 80 | elf_ehdr_ptr = (Elf32_Ehdr *) &elf_header; |
---|
| 81 | elf_phdr_ptr = (Elf32_Phdr *) &elf_pht[0]; |
---|
[292] | 82 | |
---|
| 83 | while(init_state != ELF_END_STATE) |
---|
| 84 | { |
---|
[425] | 85 | if (nb_available == 0 ) |
---|
[292] | 86 | { |
---|
| 87 | buffer_ptr = &boot_elf_loader_buffer[0]; |
---|
| 88 | |
---|
[425] | 89 | if (boot_ioc_read(nb_block , buffer_ptr, 1)) |
---|
[292] | 90 | { |
---|
| 91 | boot_puts ( |
---|
[388] | 92 | "ERROR: " |
---|
[425] | 93 | "boot_ioc_read() failed" |
---|
[388] | 94 | "\n" |
---|
| 95 | ); |
---|
[292] | 96 | |
---|
| 97 | boot_exit(); |
---|
| 98 | } |
---|
[388] | 99 | |
---|
[292] | 100 | nb_block += 1; |
---|
| 101 | nb_available = 512; |
---|
| 102 | } |
---|
| 103 | |
---|
| 104 | nb_read = (nb_rest <= nb_available) ? nb_rest : nb_available; |
---|
| 105 | offset += nb_read; |
---|
| 106 | |
---|
[412] | 107 | #if (BOOT_DEBUG == 1) |
---|
| 108 | if (init_state != init_state_debug) |
---|
| 109 | { |
---|
[415] | 110 | boot_puts("\ninit_state = "); |
---|
[412] | 111 | boot_puts(init_state_str[init_state]); |
---|
| 112 | boot_puts("\n"); |
---|
| 113 | init_state_debug = init_state; |
---|
| 114 | } |
---|
| 115 | #endif |
---|
| 116 | |
---|
[292] | 117 | switch(init_state) |
---|
| 118 | { |
---|
[425] | 119 | /* |
---|
[292] | 120 | * Reading ELF executable header |
---|
| 121 | */ |
---|
| 122 | case ELF_HEADER_STATE: |
---|
[425] | 123 | memcpy(elf_ehdr_ptr, buffer_ptr, nb_read); |
---|
[292] | 124 | |
---|
| 125 | nb_rest -= nb_read; |
---|
| 126 | |
---|
| 127 | if(nb_rest == 0) |
---|
| 128 | { |
---|
[425] | 129 | nb_rest = elf_ehdr_ptr->e_phnum * elf_ehdr_ptr->e_phentsize; |
---|
[292] | 130 | |
---|
[425] | 131 | /* |
---|
| 132 | * Verification of ELF Magic Number |
---|
| 133 | */ |
---|
| 134 | if ( (elf_ehdr_ptr->e_ident[EI_MAG0] != ELFMAG0) || |
---|
| 135 | (elf_ehdr_ptr->e_ident[EI_MAG1] != ELFMAG1) || |
---|
| 136 | (elf_ehdr_ptr->e_ident[EI_MAG2] != ELFMAG2) || |
---|
| 137 | (elf_ehdr_ptr->e_ident[EI_MAG3] != ELFMAG3) ) |
---|
[388] | 138 | { |
---|
| 139 | boot_puts( |
---|
| 140 | "ERROR: " |
---|
| 141 | "Input file does not use ELF format" |
---|
| 142 | "\n" |
---|
[412] | 143 | ); |
---|
[292] | 144 | |
---|
[388] | 145 | boot_exit(); |
---|
| 146 | } |
---|
[292] | 147 | |
---|
[412] | 148 | /* |
---|
[388] | 149 | * Verification of Program Headers table size. It must be |
---|
[412] | 150 | * smaller than the work size allocated for the |
---|
[388] | 151 | * elf_pht[PHDR_ARRAY_SIZE] array |
---|
[425] | 152 | */ |
---|
| 153 | if (elf_ehdr_ptr->e_phnum > PHDR_ARRAY_SIZE) |
---|
[292] | 154 | { |
---|
| 155 | boot_puts( |
---|
[388] | 156 | "ERROR: " |
---|
[425] | 157 | "ELF PHDR table size is bigger than the allocated" |
---|
| 158 | "work space" |
---|
[388] | 159 | "\n" |
---|
| 160 | ); |
---|
[292] | 161 | |
---|
| 162 | boot_exit(); |
---|
| 163 | } |
---|
| 164 | |
---|
| 165 | init_state = ELF_PROGRAM_HEADER_STATE; |
---|
| 166 | } |
---|
| 167 | |
---|
| 168 | break; |
---|
| 169 | |
---|
[425] | 170 | /* |
---|
[292] | 171 | * Reading ELF program headers |
---|
[412] | 172 | */ |
---|
[292] | 173 | case ELF_PROGRAM_HEADER_STATE: |
---|
[425] | 174 | memcpy(elf_phdr_ptr, buffer_ptr, nb_read); |
---|
[292] | 175 | |
---|
[425] | 176 | elf_phdr_ptr = |
---|
| 177 | (Elf32_Phdr *)((unsigned char *) elf_phdr_ptr + nb_read); |
---|
[292] | 178 | |
---|
[425] | 179 | nb_rest -= nb_read; |
---|
| 180 | |
---|
[292] | 181 | if(nb_rest == 0) |
---|
| 182 | { |
---|
[425] | 183 | elf_phdr_ptr = (Elf32_Phdr *) &elf_pht[0]; |
---|
[292] | 184 | |
---|
| 185 | /* |
---|
| 186 | * Search the first not NULL segment in the ELF file |
---|
| 187 | */ |
---|
[425] | 188 | for (pseg = 0; pseg < elf_ehdr_ptr->e_phnum; pseg++) |
---|
[292] | 189 | { |
---|
[425] | 190 | if(elf_phdr_ptr[pseg].p_type == PT_LOAD) |
---|
[292] | 191 | { |
---|
[412] | 192 | #if (BOOT_DEBUG == 1) |
---|
[425] | 193 | boot_puts("loadable segment found:\n"); |
---|
| 194 | boot_print_elf_phdr(&elf_phdr_ptr[pseg]); |
---|
[412] | 195 | #endif |
---|
[425] | 196 | if (elf_phdr_ptr[pseg].p_offset < offset) |
---|
[412] | 197 | { |
---|
[415] | 198 | /* |
---|
[425] | 199 | * Case where the segment to load includes the |
---|
| 200 | * elf and program headers |
---|
| 201 | */ |
---|
| 202 | nb_rest = elf_phdr_ptr[pseg].p_filesz - offset; |
---|
[412] | 203 | init_state = ELF_SEGMENT_STATE; |
---|
| 204 | } |
---|
| 205 | else |
---|
| 206 | { |
---|
[415] | 207 | /* |
---|
| 208 | * Segment to load is further away in ELF file |
---|
[425] | 209 | */ |
---|
| 210 | nb_rest = elf_phdr_ptr[pseg].p_offset - offset; |
---|
[412] | 211 | init_state = ELF_OFFSET_STATE; |
---|
| 212 | } |
---|
[292] | 213 | break; |
---|
| 214 | } |
---|
| 215 | } |
---|
| 216 | |
---|
[425] | 217 | if (pseg == elf_ehdr_ptr->e_phnum) |
---|
[412] | 218 | { |
---|
| 219 | boot_puts( |
---|
| 220 | "ERROR: " |
---|
| 221 | "No PT_LOAD found" |
---|
| 222 | "\n" |
---|
| 223 | ); |
---|
| 224 | boot_exit(); |
---|
| 225 | } |
---|
| 226 | |
---|
[292] | 227 | } |
---|
| 228 | |
---|
| 229 | break; |
---|
| 230 | |
---|
[425] | 231 | /* |
---|
[415] | 232 | * Go to the offset of the first not null program segment in the |
---|
| 233 | * ELF file |
---|
[425] | 234 | * |
---|
| 235 | * TODO: |
---|
| 236 | * No need to read from the disk the useless bytes. Try to compute |
---|
| 237 | * the next usefull lba |
---|
[292] | 238 | */ |
---|
| 239 | case ELF_OFFSET_STATE: |
---|
| 240 | nb_rest -= nb_read; |
---|
| 241 | |
---|
| 242 | if (nb_rest == 0) |
---|
| 243 | { |
---|
[425] | 244 | nb_rest = elf_phdr_ptr[pseg].p_filesz; |
---|
[292] | 245 | init_state = ELF_SEGMENT_STATE; |
---|
| 246 | } |
---|
| 247 | |
---|
| 248 | break; |
---|
| 249 | |
---|
[425] | 250 | /* |
---|
[292] | 251 | * Reading ELF segments |
---|
[425] | 252 | * |
---|
| 253 | * TODO: |
---|
| 254 | * Do not pass by block buffer but write directly in target memory |
---|
| 255 | * address |
---|
[292] | 256 | */ |
---|
| 257 | case ELF_SEGMENT_STATE: |
---|
[425] | 258 | /* |
---|
| 259 | * Verify that loadable segment does not conflict with |
---|
| 260 | * pre-loader memory space |
---|
[412] | 261 | */ |
---|
[425] | 262 | pseg_start = elf_phdr_ptr[pseg].p_vaddr; |
---|
[292] | 263 | |
---|
[425] | 264 | pseg_end = elf_phdr_ptr[pseg].p_vaddr + |
---|
| 265 | elf_phdr_ptr[pseg].p_memsz; |
---|
| 266 | |
---|
| 267 | if ((pseg_start >= 0xBFC00000 && pseg_start <= 0xBFC10000) || |
---|
| 268 | (pseg_end >= 0xBFC00000 && pseg_end <= 0xBFC10000) || |
---|
| 269 | (pseg_start < 0xBFC00000 && pseg_end > 0xBFC10000)) |
---|
[292] | 270 | { |
---|
[425] | 271 | boot_puts( |
---|
| 272 | "ERROR: " |
---|
| 273 | "Program segment conflits with pre-loader memory space" |
---|
| 274 | "\n" |
---|
| 275 | ); |
---|
| 276 | boot_exit(); |
---|
[292] | 277 | } |
---|
[412] | 278 | |
---|
[425] | 279 | /* |
---|
| 280 | * Copy the ELF segment data in memory using the |
---|
| 281 | * virtual address obtained from the ELF file |
---|
| 282 | */ |
---|
| 283 | pseg_ptr = (unsigned char *) |
---|
| 284 | elf_phdr_ptr[pseg].p_vaddr + |
---|
| 285 | elf_phdr_ptr[pseg].p_filesz - |
---|
| 286 | nb_rest; |
---|
| 287 | |
---|
| 288 | memcpy(pseg_ptr, buffer_ptr, nb_read); |
---|
| 289 | |
---|
[292] | 290 | nb_rest -= nb_read; |
---|
| 291 | |
---|
[425] | 292 | if (nb_rest == 0) |
---|
[292] | 293 | { |
---|
[425] | 294 | /* |
---|
| 295 | * Fill remaining bytes with zeros (filesz < memsz) |
---|
| 296 | */ |
---|
| 297 | pseg_remainder = |
---|
| 298 | elf_phdr_ptr[pseg].p_memsz - |
---|
| 299 | elf_phdr_ptr[pseg].p_filesz ; |
---|
[292] | 300 | |
---|
[425] | 301 | pseg_ptr = (unsigned char *) |
---|
| 302 | elf_phdr_ptr[pseg].p_vaddr + |
---|
| 303 | elf_phdr_ptr[pseg].p_filesz ; |
---|
[292] | 304 | |
---|
[425] | 305 | memset(pseg_ptr, 0, pseg_remainder); |
---|
| 306 | |
---|
| 307 | boot_puts("Copied segment at address "); |
---|
| 308 | boot_putx(elf_phdr_ptr[pseg].p_vaddr); |
---|
| 309 | boot_puts("\n"); |
---|
| 310 | |
---|
[292] | 311 | /* |
---|
[425] | 312 | * Search the next first not NULL segment in the ELF file |
---|
[292] | 313 | */ |
---|
[425] | 314 | for (pseg += 1; pseg < elf_ehdr_ptr->e_phnum; pseg++) |
---|
| 315 | { |
---|
| 316 | if(elf_phdr_ptr[pseg].p_type == PT_LOAD) |
---|
[292] | 317 | { |
---|
[425] | 318 | #if (BOOT_DEBUG == 1) |
---|
| 319 | boot_puts("loadable segment found:\n"); |
---|
| 320 | boot_print_elf_phdr(&elf_phdr_ptr[pseg]); |
---|
| 321 | #endif |
---|
| 322 | nb_rest = elf_phdr_ptr[pseg].p_offset - offset; |
---|
[292] | 323 | break; |
---|
| 324 | } |
---|
| 325 | } |
---|
| 326 | |
---|
| 327 | /* |
---|
| 328 | * Program loading finished |
---|
[412] | 329 | */ |
---|
[425] | 330 | if(pseg == elf_ehdr_ptr->e_phnum) |
---|
[292] | 331 | { |
---|
| 332 | init_state = ELF_END_STATE; |
---|
| 333 | break; |
---|
| 334 | } |
---|
| 335 | |
---|
| 336 | init_state = ELF_OFFSET_STATE; |
---|
| 337 | } |
---|
| 338 | break; |
---|
| 339 | |
---|
| 340 | default: |
---|
| 341 | break; |
---|
| 342 | } |
---|
| 343 | |
---|
[425] | 344 | buffer_ptr += nb_read; |
---|
| 345 | nb_available -= nb_read; |
---|
[292] | 346 | } |
---|
| 347 | |
---|
| 348 | boot_puts ( |
---|
[388] | 349 | "Finishing boot_elf_loader function.\n" |
---|
| 350 | "Entry point address: " |
---|
| 351 | ); |
---|
[425] | 352 | |
---|
| 353 | boot_putx(elf_ehdr_ptr->e_entry); |
---|
[292] | 354 | boot_puts("\n"); |
---|
| 355 | |
---|
[425] | 356 | return ((void *) elf_ehdr_ptr->e_entry); |
---|
[292] | 357 | } |
---|
[425] | 358 | |
---|
| 359 | // vim: tabstop=4 : softtabstop=4 : shiftwidth=4 : expandtab |
---|