git.rot13.org Git - simavr/blob - simavr/sim/sim_elf.c

   1 /*
   2         sim_elf.c
   3
   4         Loads a .elf file, extract the code, the data, the eeprom and
   5         the "mcu" specification section, also load usable code symbols
   6         to be able to print meaningful trace information.
   7
   8         Copyright 2008, 2009 Michel Pollet <buserror@gmail.com>
   9
  10         This file is part of simavr.
  11
  12         simavr is free software: you can redistribute it and/or modify
  13         it under the terms of the GNU General Public License as published by
  14         the Free Software Foundation, either version 3 of the License, or
  15         (at your option) any later version.
  16
  17         simavr is distributed in the hope that it will be useful,
  18         but WITHOUT ANY WARRANTY; without even the implied warranty of
  19         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20         GNU General Public License for more details.
  21
  22         You should have received a copy of the GNU General Public License
  23         along with simavr.  If not, see <http://www.gnu.org/licenses/>.
  24  */
  25
  26 #include <sys/stat.h>
  27 #include <fcntl.h>
  28 #include <unistd.h>
  29 #include <stdlib.h>
  30 #include <stdio.h>
  31 #include <string.h>
  32 #include <libelf.h>
  33 #include <gelf.h>
  34
  35 #include "sim_elf.h"
  36
  37 int elf_read_firmware(const char * file, elf_firmware_t * firmware)
  38 {
  39         Elf32_Ehdr elf_header;                  /* ELF header */
  40         Elf *elf = NULL;                       /* Our Elf pointer for libelf */
  41         int fd; // File Descriptor
  42
  43         if ((fd = open(file, O_RDONLY)) == -1 ||
  44                         (read(fd, &elf_header, sizeof(elf_header))) < sizeof(elf_header)) {
  45                 printf("could not read %s\n", file);
  46                 perror(file);
  47                 close(fd);
  48                 return -1;
  49         }
  50
  51         Elf_Data *data_data = NULL,
  52                 *data_text = NULL,
  53                 *data_ee = NULL;                /* Data Descriptor */
  54
  55         memset(firmware, 0, sizeof(*firmware));
  56 #if ELF_SYMBOLS
  57         //int bitesize = ((avr->flashend+1) >> 1) * sizeof(avr_symbol_t);
  58         firmware->codesize = 32768;
  59         int bitesize = firmware->codesize * sizeof(avr_symbol_t);
  60         firmware->codeline = malloc(bitesize);
  61         memset(firmware->codeline,0, bitesize);
  62 #endif
  63
  64         /* this is actualy mandatory !! otherwise elf_begin() fails */
  65         if (elf_version(EV_CURRENT) == EV_NONE) {
  66                         /* library out of date - recover from error */
  67         }
  68         // Iterate through section headers again this time well stop when we find symbols
  69         elf = elf_begin(fd, ELF_C_READ, NULL);
  70         //printf("Loading elf %s : %p\n", file, elf);
  71
  72         Elf_Scn *scn = NULL;                   /* Section Descriptor */
  73
  74         while ((scn = elf_nextscn(elf, scn)) != NULL) {
  75                 GElf_Shdr shdr;                 /* Section Header */
  76                 gelf_getshdr(scn, &shdr);
  77                 char * name = elf_strptr(elf, elf_header.e_shstrndx, shdr.sh_name);
  78         //      printf("Walking elf section '%s'\n", name);
  79
  80                 if (!strcmp(name, ".text"))
  81                         data_text = elf_getdata(scn, NULL);
  82                 else if (!strcmp(name, ".data"))
  83                         data_data = elf_getdata(scn, NULL);
  84                 else if (!strcmp(name, ".eeprom"))
  85                         data_ee = elf_getdata(scn, NULL);
  86                 else if (!strcmp(name, ".bss")) {
  87                         Elf_Data *s = elf_getdata(scn, NULL);
  88                         firmware->bsssize = s->d_size;
  89                 } else if (!strcmp(name, ".mmcu")) {
  90                         Elf_Data *s = elf_getdata(scn, NULL);
  91                         firmware->mmcu = *((struct avr_mcu_t*)s->d_buf);
  92                         printf("%s: avr_mcu_t size %ld / read %ld\n", __FUNCTION__, sizeof(struct avr_mcu_t), s->d_size);
  93                 //      avr->frequency = f_cpu;
  94                 }
  95 #if ELF_SYMBOLS
  96                 // When we find a section header marked SHT_SYMTAB stop and get symbols
  97                 if (shdr.sh_type == SHT_SYMTAB) {
  98                         // edata points to our symbol table
  99                         Elf_Data *edata = elf_getdata(scn, NULL);
 100
 101                         // how many symbols are there? this number comes from the size of
 102                         // the section divided by the entry size
 103                         int symbol_count = shdr.sh_size / shdr.sh_entsize;
 104
 105                         // loop through to grab all symbols
 106                         for (int i = 0; i < symbol_count; i++) {
 107                                 GElf_Sym sym;                   /* Symbol */
 108                                 // libelf grabs the symbol data using gelf_getsym()
 109                                 gelf_getsym(edata, i, &sym);
 110
 111                                 // print out the value and size
 112                         //      printf("%08x %08d ", sym.st_value, sym.st_size);
 113                                 if (ELF32_ST_BIND(sym.st_info) == STB_GLOBAL ||
 114                                                 ELF32_ST_TYPE(sym.st_info) == STT_FUNC ||
 115                                                 ELF32_ST_TYPE(sym.st_info) == STT_OBJECT) {
 116                                         const char * name = elf_strptr(elf, shdr.sh_link, sym.st_name);
 117
 118                                         // type of symbol
 119                                         if (sym.st_value & 0xfff00000) {
 120
 121                                         } else {
 122                                                 // code
 123                                                 if (firmware->codeline[sym.st_value >> 1] == NULL) {
 124                                                         avr_symbol_t * s = firmware->codeline[sym.st_value >> 1] = malloc(sizeof(avr_symbol_t*));
 125                                                         s->symbol = strdup(name);
 126                                                         s->addr = sym.st_value;
 127                                                 }
 128                                         }
 129                                 }
 130                         }
 131                 }
 132 #endif
 133         }
 134 #if ELF_SYMBOLS
 135         avr_symbol_t * last = NULL;
 136         for (int i = 0; i < firmware->codesize; i++) {
 137                 if (!firmware->codeline[i])
 138                         firmware->codeline[i] = last;
 139                 else
 140                         last = firmware->codeline[i];
 141         }
 142 #endif
 143         uint32_t offset = 0;
 144         firmware->flashsize =
 145                         (data_text ? data_text->d_size : 0) +
 146                         (data_data ? data_data->d_size : 0);
 147         firmware->flash = malloc(firmware->flashsize);
 148         if (data_text) {
 149         //      hdump("code", data_text->d_buf, data_text->d_size);
 150                 memcpy(firmware->flash + offset, data_text->d_buf, data_text->d_size);
 151                 offset += data_text->d_size;
 152                 printf("Loaded %d .text\n", data_text->d_size);
 153         }
 154         if (data_data) {
 155         //      hdump("data", data_data->d_buf, data_data->d_size);
 156                 memcpy(firmware->flash + offset, data_data->d_buf, data_data->d_size);
 157                 printf("Loaded %d .data\n", data_data->d_size);
 158                 offset += data_data->d_size;
 159                 firmware->datasize = data_data->d_size;
 160         }
 161         if (data_ee) {
 162         //      hdump("eeprom", data_ee->d_buf, data_ee->d_size);
 163                 firmware->eeprom = malloc(data_ee->d_size);
 164                 memcpy(firmware->eeprom, data_ee->d_buf, data_ee->d_size);
 165                 printf("Loaded %d .eeprom\n", data_ee->d_size);
 166                 firmware->eesize = data_ee->d_size;
 167         }
 168 //      hdump("flash", avr->flash, offset);
 169         elf_end(elf);
 170         close(fd);
 171         return 0;
 172 }
 173