[292] | 1 | /** |
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[425] | 2 | * \file : boot_elf_loader.c |
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[292] | 3 | * \date : August 2012 |
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| 4 | * \author : Cesar Fuguet |
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| 5 | * |
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| 6 | * This file defines an elf file loader which reads an executable elf file |
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| 7 | * starting at a sector passed as argument of a disk and copy the different |
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| 8 | * ELF program segments in the appropriate memory address using as information |
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| 9 | * the virtual address read from the elf file. |
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| 10 | */ |
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| 11 | |
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| 12 | #include <boot_ioc.h> |
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| 13 | #include <elf-types.h> |
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| 14 | #include <boot_tty.h> |
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[425] | 15 | #include <boot_utils.h> |
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[292] | 16 | #include <defs.h> |
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| 17 | |
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[425] | 18 | #if (BOOT_DEBUG == 1) |
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[554] | 19 | static char const * const init_state_str[] = { |
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[425] | 20 | "ELF_HEADER_STATE", |
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| 21 | "ELF_PROGRAM_HEADER_STATE", |
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| 22 | "ELF_OFFSET_STATE", |
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| 23 | "ELF_SEGMENT_STATE", |
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| 24 | "ELF_END_STATE" |
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| 25 | }; |
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| 26 | #endif |
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| 27 | |
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[570] | 28 | unsigned char boot_elf_loader_buffer[512] __attribute__((aligned(CACHE_LINE_SIZE))); |
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| 29 | |
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[292] | 30 | void * boot_elf_loader(unsigned int lba) |
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| 31 | { |
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[425] | 32 | /* |
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[292] | 33 | * Temporary variables used by the boot loader |
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| 34 | */ |
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| 35 | Elf32_Ehdr elf_header; |
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| 36 | Elf32_Phdr elf_pht[PHDR_ARRAY_SIZE]; |
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| 37 | |
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| 38 | unsigned char * buffer_ptr; |
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[425] | 39 | Elf32_Ehdr * elf_ehdr_ptr; |
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| 40 | Elf32_Phdr * elf_phdr_ptr; |
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[292] | 41 | |
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| 42 | unsigned int nb_available; |
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| 43 | unsigned int nb_rest; |
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| 44 | unsigned int nb_read; |
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| 45 | unsigned int nb_block; |
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| 46 | unsigned int offset; |
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[425] | 47 | |
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| 48 | unsigned char * pseg_ptr; |
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| 49 | unsigned int pseg_start; |
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| 50 | unsigned int pseg_end; |
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| 51 | unsigned int pseg_remainder; |
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[292] | 52 | unsigned int pseg; |
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[412] | 53 | |
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[292] | 54 | /* |
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| 55 | * Loader state machine definition |
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[412] | 56 | */ |
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[425] | 57 | typedef enum |
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[292] | 58 | { |
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| 59 | ELF_HEADER_STATE, |
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| 60 | ELF_PROGRAM_HEADER_STATE, |
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| 61 | ELF_OFFSET_STATE, |
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| 62 | ELF_SEGMENT_STATE, |
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| 63 | ELF_END_STATE |
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[425] | 64 | } elf_loader_t; |
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[292] | 65 | |
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[425] | 66 | elf_loader_t init_state; |
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| 67 | init_state = ELF_HEADER_STATE; |
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| 68 | |
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[412] | 69 | #if (BOOT_DEBUG == 1) |
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[425] | 70 | elf_loader_t init_state_debug; |
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| 71 | init_state_debug = ELF_END_STATE; |
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[412] | 72 | #endif |
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| 73 | |
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[292] | 74 | boot_puts("Starting boot_elf_loader function...\n\r"); |
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| 75 | |
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[425] | 76 | nb_block = lba; |
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| 77 | nb_available = 0; |
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| 78 | nb_rest = sizeof(Elf32_Ehdr); |
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| 79 | pseg = 0; |
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| 80 | offset = 0; |
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| 81 | elf_ehdr_ptr = (Elf32_Ehdr *) &elf_header; |
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| 82 | elf_phdr_ptr = (Elf32_Phdr *) &elf_pht[0]; |
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[292] | 83 | |
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| 84 | while(init_state != ELF_END_STATE) |
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| 85 | { |
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[425] | 86 | if (nb_available == 0 ) |
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[292] | 87 | { |
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| 88 | buffer_ptr = &boot_elf_loader_buffer[0]; |
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| 89 | |
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[425] | 90 | if (boot_ioc_read(nb_block , buffer_ptr, 1)) |
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[292] | 91 | { |
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| 92 | boot_puts ( |
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[388] | 93 | "ERROR: " |
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[425] | 94 | "boot_ioc_read() failed" |
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[388] | 95 | "\n" |
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| 96 | ); |
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[292] | 97 | |
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| 98 | boot_exit(); |
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| 99 | } |
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[388] | 100 | |
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[292] | 101 | nb_block += 1; |
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| 102 | nb_available = 512; |
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| 103 | } |
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| 104 | |
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| 105 | nb_read = (nb_rest <= nb_available) ? nb_rest : nb_available; |
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| 106 | offset += nb_read; |
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| 107 | |
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[412] | 108 | #if (BOOT_DEBUG == 1) |
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| 109 | if (init_state != init_state_debug) |
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| 110 | { |
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[415] | 111 | boot_puts("\ninit_state = "); |
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[412] | 112 | boot_puts(init_state_str[init_state]); |
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| 113 | boot_puts("\n"); |
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| 114 | init_state_debug = init_state; |
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| 115 | } |
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| 116 | #endif |
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| 117 | |
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[292] | 118 | switch(init_state) |
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| 119 | { |
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[425] | 120 | /* |
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[292] | 121 | * Reading ELF executable header |
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| 122 | */ |
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| 123 | case ELF_HEADER_STATE: |
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[425] | 124 | memcpy(elf_ehdr_ptr, buffer_ptr, nb_read); |
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[292] | 125 | |
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| 126 | nb_rest -= nb_read; |
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| 127 | |
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| 128 | if(nb_rest == 0) |
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| 129 | { |
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[425] | 130 | nb_rest = elf_ehdr_ptr->e_phnum * elf_ehdr_ptr->e_phentsize; |
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[292] | 131 | |
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[425] | 132 | /* |
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| 133 | * Verification of ELF Magic Number |
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| 134 | */ |
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| 135 | if ( (elf_ehdr_ptr->e_ident[EI_MAG0] != ELFMAG0) || |
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| 136 | (elf_ehdr_ptr->e_ident[EI_MAG1] != ELFMAG1) || |
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| 137 | (elf_ehdr_ptr->e_ident[EI_MAG2] != ELFMAG2) || |
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| 138 | (elf_ehdr_ptr->e_ident[EI_MAG3] != ELFMAG3) ) |
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[388] | 139 | { |
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| 140 | boot_puts( |
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| 141 | "ERROR: " |
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| 142 | "Input file does not use ELF format" |
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| 143 | "\n" |
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[412] | 144 | ); |
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[292] | 145 | |
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[388] | 146 | boot_exit(); |
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| 147 | } |
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[292] | 148 | |
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[412] | 149 | /* |
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[388] | 150 | * Verification of Program Headers table size. It must be |
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[412] | 151 | * smaller than the work size allocated for the |
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[388] | 152 | * elf_pht[PHDR_ARRAY_SIZE] array |
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[425] | 153 | */ |
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| 154 | if (elf_ehdr_ptr->e_phnum > PHDR_ARRAY_SIZE) |
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[292] | 155 | { |
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| 156 | boot_puts( |
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[388] | 157 | "ERROR: " |
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[425] | 158 | "ELF PHDR table size is bigger than the allocated" |
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| 159 | "work space" |
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[388] | 160 | "\n" |
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| 161 | ); |
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[292] | 162 | |
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| 163 | boot_exit(); |
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| 164 | } |
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| 165 | |
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| 166 | init_state = ELF_PROGRAM_HEADER_STATE; |
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| 167 | } |
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| 168 | |
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| 169 | break; |
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| 170 | |
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[425] | 171 | /* |
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[292] | 172 | * Reading ELF program headers |
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[412] | 173 | */ |
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[292] | 174 | case ELF_PROGRAM_HEADER_STATE: |
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[425] | 175 | memcpy(elf_phdr_ptr, buffer_ptr, nb_read); |
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[292] | 176 | |
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[425] | 177 | elf_phdr_ptr = |
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| 178 | (Elf32_Phdr *)((unsigned char *) elf_phdr_ptr + nb_read); |
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[292] | 179 | |
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[425] | 180 | nb_rest -= nb_read; |
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| 181 | |
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[292] | 182 | if(nb_rest == 0) |
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| 183 | { |
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[425] | 184 | elf_phdr_ptr = (Elf32_Phdr *) &elf_pht[0]; |
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[292] | 185 | |
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| 186 | /* |
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| 187 | * Search the first not NULL segment in the ELF file |
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| 188 | */ |
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[425] | 189 | for (pseg = 0; pseg < elf_ehdr_ptr->e_phnum; pseg++) |
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[292] | 190 | { |
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[425] | 191 | if(elf_phdr_ptr[pseg].p_type == PT_LOAD) |
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[292] | 192 | { |
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[412] | 193 | #if (BOOT_DEBUG == 1) |
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[425] | 194 | boot_puts("loadable segment found:\n"); |
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| 195 | boot_print_elf_phdr(&elf_phdr_ptr[pseg]); |
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[412] | 196 | #endif |
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[425] | 197 | if (elf_phdr_ptr[pseg].p_offset < offset) |
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[412] | 198 | { |
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[415] | 199 | /* |
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[425] | 200 | * Case where the segment to load includes the |
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| 201 | * elf and program headers |
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| 202 | */ |
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| 203 | nb_rest = elf_phdr_ptr[pseg].p_filesz - offset; |
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[412] | 204 | init_state = ELF_SEGMENT_STATE; |
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| 205 | } |
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| 206 | else |
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| 207 | { |
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[415] | 208 | /* |
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| 209 | * Segment to load is further away in ELF file |
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[425] | 210 | */ |
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| 211 | nb_rest = elf_phdr_ptr[pseg].p_offset - offset; |
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[412] | 212 | init_state = ELF_OFFSET_STATE; |
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| 213 | } |
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[292] | 214 | break; |
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| 215 | } |
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| 216 | } |
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| 217 | |
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[425] | 218 | if (pseg == elf_ehdr_ptr->e_phnum) |
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[412] | 219 | { |
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| 220 | boot_puts( |
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| 221 | "ERROR: " |
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| 222 | "No PT_LOAD found" |
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| 223 | "\n" |
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| 224 | ); |
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| 225 | boot_exit(); |
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| 226 | } |
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| 227 | |
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[292] | 228 | } |
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| 229 | |
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| 230 | break; |
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| 231 | |
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[425] | 232 | /* |
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[415] | 233 | * Go to the offset of the first not null program segment in the |
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| 234 | * ELF file |
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[425] | 235 | * |
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| 236 | * TODO: |
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| 237 | * No need to read from the disk the useless bytes. Try to compute |
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| 238 | * the next usefull lba |
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[292] | 239 | */ |
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| 240 | case ELF_OFFSET_STATE: |
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| 241 | nb_rest -= nb_read; |
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| 242 | |
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| 243 | if (nb_rest == 0) |
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| 244 | { |
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[425] | 245 | nb_rest = elf_phdr_ptr[pseg].p_filesz; |
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[292] | 246 | init_state = ELF_SEGMENT_STATE; |
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| 247 | } |
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| 248 | |
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| 249 | break; |
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| 250 | |
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[425] | 251 | /* |
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[292] | 252 | * Reading ELF segments |
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[425] | 253 | * |
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| 254 | * TODO: |
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| 255 | * Do not pass by block buffer but write directly in target memory |
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| 256 | * address |
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[292] | 257 | */ |
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| 258 | case ELF_SEGMENT_STATE: |
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[425] | 259 | /* |
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| 260 | * Verify that loadable segment does not conflict with |
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| 261 | * pre-loader memory space |
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[412] | 262 | */ |
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[425] | 263 | pseg_start = elf_phdr_ptr[pseg].p_vaddr; |
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[292] | 264 | |
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[425] | 265 | pseg_end = elf_phdr_ptr[pseg].p_vaddr + |
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| 266 | elf_phdr_ptr[pseg].p_memsz; |
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| 267 | |
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| 268 | if ((pseg_start >= 0xBFC00000 && pseg_start <= 0xBFC10000) || |
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| 269 | (pseg_end >= 0xBFC00000 && pseg_end <= 0xBFC10000) || |
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| 270 | (pseg_start < 0xBFC00000 && pseg_end > 0xBFC10000)) |
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[292] | 271 | { |
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[425] | 272 | boot_puts( |
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| 273 | "ERROR: " |
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| 274 | "Program segment conflits with pre-loader memory space" |
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| 275 | "\n" |
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| 276 | ); |
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| 277 | boot_exit(); |
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[292] | 278 | } |
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[412] | 279 | |
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[425] | 280 | /* |
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| 281 | * Copy the ELF segment data in memory using the |
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| 282 | * virtual address obtained from the ELF file |
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| 283 | */ |
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| 284 | pseg_ptr = (unsigned char *) |
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| 285 | elf_phdr_ptr[pseg].p_vaddr + |
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| 286 | elf_phdr_ptr[pseg].p_filesz - |
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| 287 | nb_rest; |
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| 288 | |
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| 289 | memcpy(pseg_ptr, buffer_ptr, nb_read); |
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| 290 | |
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[292] | 291 | nb_rest -= nb_read; |
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| 292 | |
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[425] | 293 | if (nb_rest == 0) |
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[292] | 294 | { |
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[425] | 295 | /* |
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| 296 | * Fill remaining bytes with zeros (filesz < memsz) |
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| 297 | */ |
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| 298 | pseg_remainder = |
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| 299 | elf_phdr_ptr[pseg].p_memsz - |
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| 300 | elf_phdr_ptr[pseg].p_filesz ; |
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[292] | 301 | |
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[425] | 302 | pseg_ptr = (unsigned char *) |
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| 303 | elf_phdr_ptr[pseg].p_vaddr + |
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| 304 | elf_phdr_ptr[pseg].p_filesz ; |
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[292] | 305 | |
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[425] | 306 | memset(pseg_ptr, 0, pseg_remainder); |
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| 307 | |
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| 308 | boot_puts("Copied segment at address "); |
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| 309 | boot_putx(elf_phdr_ptr[pseg].p_vaddr); |
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| 310 | boot_puts("\n"); |
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| 311 | |
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[292] | 312 | /* |
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[425] | 313 | * Search the next first not NULL segment in the ELF file |
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[292] | 314 | */ |
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[425] | 315 | for (pseg += 1; pseg < elf_ehdr_ptr->e_phnum; pseg++) |
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| 316 | { |
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| 317 | if(elf_phdr_ptr[pseg].p_type == PT_LOAD) |
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[292] | 318 | { |
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[425] | 319 | #if (BOOT_DEBUG == 1) |
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| 320 | boot_puts("loadable segment found:\n"); |
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| 321 | boot_print_elf_phdr(&elf_phdr_ptr[pseg]); |
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| 322 | #endif |
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| 323 | nb_rest = elf_phdr_ptr[pseg].p_offset - offset; |
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[292] | 324 | break; |
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| 325 | } |
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| 326 | } |
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| 327 | |
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| 328 | /* |
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| 329 | * Program loading finished |
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[412] | 330 | */ |
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[425] | 331 | if(pseg == elf_ehdr_ptr->e_phnum) |
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[292] | 332 | { |
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| 333 | init_state = ELF_END_STATE; |
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| 334 | break; |
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| 335 | } |
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| 336 | |
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| 337 | init_state = ELF_OFFSET_STATE; |
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| 338 | } |
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| 339 | break; |
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| 340 | |
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| 341 | default: |
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| 342 | break; |
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| 343 | } |
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| 344 | |
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[425] | 345 | buffer_ptr += nb_read; |
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| 346 | nb_available -= nb_read; |
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[292] | 347 | } |
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| 348 | |
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| 349 | boot_puts ( |
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[388] | 350 | "Finishing boot_elf_loader function.\n" |
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| 351 | "Entry point address: " |
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| 352 | ); |
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[425] | 353 | |
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| 354 | boot_putx(elf_ehdr_ptr->e_entry); |
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[292] | 355 | boot_puts("\n"); |
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| 356 | |
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[425] | 357 | return ((void *) elf_ehdr_ptr->e_entry); |
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[292] | 358 | } |
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[425] | 359 | |
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| 360 | // vim: tabstop=4 : softtabstop=4 : shiftwidth=4 : expandtab |
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