kernel2/elf.c

   1 /*
   2     meinOS - A unix-like x86 microkernel operating system
   3     Copyright (C) 2008  Janosch Gräf <janosch.graef@gmx.net>
   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 <sys/types.h>
  20 #include <elf.h>
  21 #include <paging.h>
  22 #include <memuser.h>
  23 #include <memmap.h>
  24 #include <string.h>
  25 #include <debug.h>
  26 #include <cpu.h>
  27
  28 int elf_validate(elf_header_t *header) {
  29   if (header->ident[EI_MAG0]!=ELFMAG0 || header->ident[EI_MAG1]!=ELFMAG1 || header->ident[EI_MAG2]!=ELFMAG2 || header->ident[EI_MAG3]!=ELFMAG3) return -1;
  30   if (header->machine!=EM_386) return -1;
  31   if (header->ident[EI_CLASS]!=ELFCLASS32) return -1;
  32   if (header->ident[EI_DATA]!=ELFDATA2LSB) return -1;
  33   if (header->ident[EI_VERSION]!=header->version) return -1;
  34   return 0;
  35 }
  36
  37 /**
  38  * Loads an ELF segment in address space
  39  *  @param memaddr Destination address in memory
  40  *  @param memsize Size in memory
  41  *  @param fileaddr Source address in file (absolute)
  42  *  @param filesize Size in file
  43  *  @param addrspace User address space
  44  *  @param writable If segment is writeable
  45  */
  46 int elf_loadseg(void *memaddr,size_t memsize,void *fileaddr,size_t filesize,addrspace_t *addrspace,int writable) {
  47   size_t i;
  48
  49   if (memaddr<(void*)USERDATA_ADDRESS) return -1;
  50   if (memuser_load_addrspace(addrspace)==-1) return -1;
  51   for (i=0;i<memsize;i+=PAGE_SIZE) {
  52     if (memuser_alloc_at(addrspace,memaddr+i,i<filesize?paging_getphysaddr(fileaddr+i):NULL,writable)==-1) return -1;
  53   }
  54   if (filesize<memsize) memset(memaddr+filesize,0,memsize-filesize);
  55   return 0;
  56 }
  57
  58 /**
  59  * Loads an ELF file in an address space
  60  *  @param addrspace Address space
  61  *  @param file Pointer to ELF file
  62  *  @param filesize Size of ELF file
  63  *  @return Entrypoint
  64  */
  65 void *elf_load(addrspace_t *addrspace,void *file,size_t filesize) {
  66   elf_header_t *header = file;
  67   elf_progheader_t *progheader;
  68   void *entrypoint;
  69   size_t i;
  70
  71   if (elf_validate(header)==-1) return NULL;
  72
  73   entrypoint = (void*)(header->entry);
  74   progheader = file+header->phoff;
  75
  76   for (i=0;i<header->phnum;i++) {
  77     if (progheader[i].type==PT_LOAD) {
  78       if (elf_loadseg((void*)(progheader[i].vaddr),progheader[i].memsz,file+progheader[i].offset,progheader[i].filesz,addrspace,(progheader[i].flags&PF_W)==PF_W?1:0)==-1) return NULL;
  79     }
  80   }
  81
  82   return entrypoint;
  83 }