bootloader/elf32.c

   1 /*
   2     e07 bootloader suite
   3     Copyright (c) 2008 Daniel Mack <daniel@caiaq.de>
   4
   5     This program is free software: you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation, either version 3 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19 #include "regs.h"
  20 #include "types.h"
  21 #include "wikireader.h"
  22 #include "misc.h"
  23 #include <tff.h>
  24 #include <string.h>
  25
  26 #define ET_EXEC         2
  27 #define EM_C33          0x6b
  28
  29 #define ELFMAG0         0x7f
  30 #define ELFMAG1         0x45
  31 #define ELFMAG2         0x4c
  32 #define ELFMAG3         0x46
  33
  34 typedef struct {
  35         u8  e_ident[16];        /* ELF "magic number" */
  36         u16 e_type;             /* Identifies object file type */
  37         u16 e_machine;          /* Specifies required architecture */
  38         u32 e_version;          /* Identifies object file version */
  39         u32 e_entry;            /* Entry point virtual address */
  40         u32 e_phoff;            /* Program header table file offset */
  41         u32 e_shoff;            /* Section header table file offset */
  42         u32 e_flags;            /* Processor-specific flags */
  43         u16 e_ehsize;           /* ELF header size in bytes */
  44         u16 e_phentsize;        /* Program header table entry size */
  45         u16 e_phnum;            /* Program header table entry count */
  46         u16 e_shentsize;        /* Section header table entry size */
  47         u16 e_shnum;            /* Section header table entry count */
  48         u16 e_shstrndx;         /* Section header string table index */
  49 } __attribute__((packed)) elf32_hdr;
  50
  51 typedef struct {
  52         u32 sh_name;            /* Section name, index in string tbl */
  53         u32 sh_type;            /* Type of section */
  54         u32 sh_flags;           /* Miscellaneous section attributes */
  55         u32 sh_addr;            /* Section virtual addr at execution */
  56         u32 sh_offset;          /* Section file offset */
  57         u32 sh_size;            /* Size of section in bytes */
  58         u32 sh_link;            /* Index of another section */
  59         u32 sh_info;            /* Additional section information */
  60         u32 sh_addralign;       /* Section alignment */
  61         u32 sh_entsize;         /* Entry size if section holds table */
  62 } __attribute__((packed)) elf32_sec;
  63
  64 #define SHT_NULL        0       /* Section header table entry unused */
  65 #define SHT_PROGBITS    1       /* Program specific (private) data */
  66 #define SHT_SYMTAB      2       /* Link editing symbol table */
  67 #define SHT_STRTAB      3       /* A string table */
  68 #define SHT_RELA        4       /* Relocation entries with addends */
  69 #define SHT_HASH        5       /* A symbol hash table */
  70 #define SHT_DYNAMIC     6       /* Information for dynamic linking */
  71 #define SHT_NOTE        7       /* Information that marks file */
  72 #define SHT_NOBITS      8       /* Section occupies no space in file */
  73 #define SHT_REL         9       /* Relocation entries, no addends */
  74 #define SHT_SHLIB       10      /* Reserved, unspecified semantics */
  75 #define SHT_DYNSYM      11      /* Dynamic linking symbol table */
  76
  77
  78 int elf_exec(const u8 *filename)
  79 {
  80         elf32_hdr hdr;
  81         elf32_sec sec;
  82         u32 i, r;
  83         void *exec;
  84         FATFS fatfs;
  85         FIL file;
  86         int rc = 0;
  87
  88         if (f_mount(0, &fatfs) != FR_OK) {
  89                 rc = -1;
  90                 goto abort_umount;
  91         }
  92
  93         if (f_open(&file, filename, FA_READ) != FR_OK) {
  94                 rc = -2;
  95                 goto abort_umount;
  96         }
  97
  98         if (f_read(&file, &hdr, sizeof(hdr), &r) || r != sizeof(hdr)) {
  99                 rc = -3;
 100                 goto abort_close;
 101         }
 102
 103         if (hdr.e_ident[0] != ELFMAG0 ||
 104             hdr.e_ident[1] != ELFMAG1 ||
 105             hdr.e_ident[2] != ELFMAG2 ||
 106             hdr.e_ident[3] != ELFMAG3) {
 107                 /* print("invalid ELF magic\n"); */
 108                 rc = -4;
 109                 goto abort_close;
 110         }
 111
 112         if (hdr.e_type != ET_EXEC) {
 113                 /* print("invalid ELF file type\n"); */
 114                 rc = -5;
 115                 goto abort_close;
 116         }
 117
 118         if (hdr.e_machine != EM_C33) {
 119                 print("FAIL: machine\n");
 120                 rc = -6;
 121                 goto abort_close;
 122         }
 123
 124         for (i = 0; i < hdr.e_shnum; i++) {
 125                 f_lseek(&file, hdr.e_shoff + sizeof(sec) * i);
 126                 if (f_read(&file, (u8 *) &sec, sizeof(sec), &r) || r != sizeof(sec))
 127                         continue;
 128
 129                 switch (sec.sh_type) {
 130                 case SHT_PROGBITS:
 131                         f_lseek(&file, sec.sh_offset);
 132                         if (f_read(&file, (u8 *) sec.sh_addr, sec.sh_size, &r) || r != sec.sh_size) {
 133                                 print("FAIL: load\n");
 134                                 rc = -7;
 135                                 goto abort_close;
 136                         } else {
 137                                 print("PROG: ");
 138                                 print_u32(sec.sh_addr);
 139                                 print("\n");
 140                         }
 141                         break;
 142                 case SHT_NOBITS:
 143                         /* clean .bss sections */
 144                         memset((u8 *) sec.sh_addr, 0, sec.sh_size);
 145                         break;
 146                 default:
 147                         break;
 148                 }
 149         }
 150
 151         f_close(&file);
 152         print("EXEC: ");
 153         print_u32(hdr.e_entry);
 154         print("\n");
 155         disable_card_power();
 156
 157         exec = (void *) hdr.e_entry;
 158         ((void (*) (void)) exec) ();
 159         goto abort_umount;
 160
 161 // make sure every thing is cleaned up if the load fails fail
 162 abort_close:
 163         f_close(&file);
 164 abort_umount:
 165         SDCARD_CS_HI();
 166         disable_card_power();
 167         return rc;
 168 }
 169