grub-mkimage.c

grub 1.95 linux 的bootloader 源代码

	Elf32_Word size = grub_le_to_cpu32 (s->sh_size);
	const char *name = strtab + grub_le_to_cpu32 (s->sh_name);
	
	if (align)
	  {
	    addr = align_address (current_address, align);
	    if (current_address != addr)
	      {
		grub_util_info ("padding %d bytes for the ELF section alignment",
				addr - current_address);
		write_padding (out, addr - current_address);
		current_address = addr;
	      }
	  }
	
	grub_util_info ("writing the text section %s at 0x%x",
			name, current_address);
	
	if (fwrite ((char *) e + offset, size, 1, out) != 1)
	  grub_util_error ("write failed");
	
	current_address += size;
      }

  addr = align_pe32_section (current_address);
  if (addr != current_address)
    {
      grub_util_info ("padding %d bytes for the PE32 section alignment",
		      addr - current_address);
      write_padding (out, addr - current_address);
    }
  
  return addr;
}

/* Write data sections.  */
static Elf32_Addr
write_data_sections (FILE *out, Elf32_Addr current_address,
		     Elf32_Ehdr *e, Elf32_Shdr *sections,
		     Elf32_Half section_entsize, Elf32_Half num_sections,
		     const char *strtab)
{
  Elf32_Half i;
  Elf32_Shdr *s;
  Elf32_Addr addr;
  
  for (i = 0, s = sections;
       i < num_sections;
       i++, s = (Elf32_Shdr *) ((char *) s + section_entsize))
    if (is_data_section (s))
      {
	Elf32_Word align = grub_le_to_cpu32 (s->sh_addralign);
	Elf32_Off offset = grub_le_to_cpu32 (s->sh_offset);
	Elf32_Word size = grub_le_to_cpu32 (s->sh_size);
	const char *name = strtab + grub_le_to_cpu32 (s->sh_name);
	
	if (align)
	  {
	    addr = align_address (current_address, align);
	    if (current_address != addr)
	      {
		grub_util_info ("padding %d bytes for the ELF section alignment",
				addr - current_address);
		write_padding (out, addr - current_address);
		current_address = addr;
	      }
	  }
	
	grub_util_info ("writing the data section %s at 0x%x",
			name, current_address);
	
	if (s->sh_type == grub_cpu_to_le32 (SHT_NOBITS))
	  write_padding (out, size);
	else
	  if (fwrite ((char *) e + offset, size, 1, out) != 1)
	    grub_util_error ("write failed");
	
	current_address += size;
      }
  
  addr = align_pe32_section (current_address);
  if (addr != current_address)
    {
      grub_util_info ("padding %d bytes for the PE32 section alignment",
		      addr - current_address);
      write_padding (out, addr - current_address);
    }
  
  return addr;
}

/* Write modules.  */
static Elf32_Addr
make_mods_section (FILE *out, Elf32_Addr current_address,
		   const char *dir, char *mods[])
{
  struct grub_util_path_list *path_list;
  grub_size_t total_module_size;
  struct grub_util_path_list *p;
  struct grub_module_info modinfo;
  Elf32_Addr addr;

  path_list = grub_util_resolve_dependencies (dir, "moddep.lst", mods);
  
  total_module_size = sizeof (struct grub_module_info);
  for (p = path_list; p; p = p->next)
    {
      total_module_size += (grub_util_get_image_size (p->name)
			    + sizeof (struct grub_module_header));
    }

  grub_util_info ("the total module size is 0x%x", total_module_size);

  modinfo.magic = grub_cpu_to_le32 (GRUB_MODULE_MAGIC);
  modinfo.offset = grub_cpu_to_le32 (sizeof (modinfo));
  modinfo.size = grub_cpu_to_le32 (total_module_size);

  if (fwrite (&modinfo, sizeof (modinfo), 1, out) != 1)
    grub_util_error ("write failed");

  for (p = path_list; p; p = p->next)
    {
      struct grub_module_header header;
      size_t mod_size;
      char *mod_image;
      
      grub_util_info ("adding module %s", p->name);
      
      mod_size = grub_util_get_image_size (p->name);
      header.offset = grub_cpu_to_le32 (sizeof (header));
      header.size = grub_cpu_to_le32 (mod_size + sizeof (header));
      
      mod_image = grub_util_read_image (p->name);

      if (fwrite (&header, sizeof (header), 1, out) != 1
	  || fwrite (mod_image, mod_size, 1, out) != 1)
	grub_util_error ("write failed");

      free (mod_image);
    }
  
  for (p = path_list; p; )
    {
      struct grub_util_path_list *q;

      q = p->next;
      free (p);
      p = q;
    }
      
  current_address += total_module_size;
  
  addr = align_pe32_section (current_address);
  if (addr != current_address)
    {
      grub_util_info ("padding %d bytes for the PE32 section alignment",
		      addr - current_address);
      write_padding (out, addr - current_address);
    }

  return addr;
}

/* Make a .reloc section.  */
static Elf32_Addr
make_reloc_section (FILE *out, Elf32_Addr current_address, Elf32_Ehdr *e, 
		    Elf32_Addr *section_addresses, Elf32_Shdr *sections,
		    Elf32_Half section_entsize, Elf32_Half num_sections,
		    const char *strtab)
{
  Elf32_Half i;
  Elf32_Shdr *s;
  struct grub_pe32_fixup_block *fixup_block = 0;
  
  for (i = 0, s = sections;
       i < num_sections;
       i++, s = (Elf32_Shdr *) ((char *) s + section_entsize))
    if (s->sh_type == grub_cpu_to_le32 (SHT_REL))
      {
	Elf32_Rel *r;
	Elf32_Word rtab_size, r_size, num_rs;
	Elf32_Off rtab_offset;
	Elf32_Addr section_address;
	Elf32_Word j;
	
	grub_util_info ("translating the relocation section %s",
			strtab + grub_le_to_cpu32 (s->sh_name));
			
	rtab_size = grub_le_to_cpu32 (s->sh_size);
	r_size = grub_le_to_cpu32 (s->sh_entsize);
	rtab_offset = grub_le_to_cpu32 (s->sh_offset);
	num_rs = rtab_size / r_size;
	
	section_address = section_addresses[grub_le_to_cpu32 (s->sh_info)];

	for (j = 0, r = (Elf32_Rel *) ((char *) e + rtab_offset);
	     j < num_rs;
	     j++, r = (Elf32_Rel *) ((char *) r + r_size))
	  {
	    Elf32_Word info;
	    Elf32_Addr offset;

	    offset = grub_le_to_cpu32 (r->r_offset);
	    info = grub_le_to_cpu32 (r->r_info);

	    /* Necessary to relocate only absolute addresses.  */
	    if (ELF32_R_TYPE (info) == R_386_32)
	      {
		Elf32_Addr addr;

		addr = section_address + offset;
		grub_util_info ("adding a relocation entry for 0x%x", addr);
		current_address = add_fixup_entry (&fixup_block,
						   GRUB_PE32_REL_BASED_HIGHLOW,
						   addr, 0, current_address,
						   out);
	      }
	  }
      }

  current_address = add_fixup_entry (&fixup_block, 0, 0, 1,
				     current_address, out);

  return current_address;
}

/* Create the header.  */
static void
make_header (FILE *out, Elf32_Addr text_address, Elf32_Addr data_address,
	     Elf32_Addr mods_address, Elf32_Addr reloc_address,
	     Elf32_Addr end_address, Elf32_Addr start_address)
{
  struct grub_pe32_header header;
  struct grub_pe32_coff_header *c;
  struct grub_pe32_optional_header *o;
  struct grub_pe32_section_table text_section, data_section;
  struct grub_pe32_section_table mods_section, reloc_section;

  /* The magic.  */
  memset (&header, 0, sizeof (header));
  memcpy (header.msdos_stub, stub, sizeof (header.msdos_stub));
  memcpy (header.signature, "PE\0\0", sizeof (header.signature));

  /* The COFF file header.  */
  c = &header.coff_header;
  c->machine = grub_cpu_to_le16 (GRUB_PE32_MACHINE_I386);
  c->num_sections = grub_cpu_to_le16 (4);
  c->time = grub_cpu_to_le32 (time (0));
  c->optional_header_size = grub_cpu_to_le16 (sizeof (header.optional_header));
  c->characteristics = grub_cpu_to_le16 (GRUB_PE32_EXECUTABLE_IMAGE
					 | GRUB_PE32_LINE_NUMS_STRIPPED
					 | GRUB_PE32_LOCAL_SYMS_STRIPPED
					 | GRUB_PE32_32BIT_MACHINE);

  /* The PE Optional header.  */
  o = &header.optional_header;
  o->magic = grub_cpu_to_le16 (GRUB_PE32_PE32_MAGIC);
  o->code_size = grub_cpu_to_le32 (data_address - text_address);
  o->data_size = grub_cpu_to_le32 (reloc_address - data_address);
  o->bss_size = 0;
  o->entry_addr = grub_cpu_to_le32 (start_address);
  o->code_base = grub_cpu_to_le32 (text_address);
  o->data_base = grub_cpu_to_le32 (data_address);
  o->image_base = 0;
  o->section_alignment = grub_cpu_to_le32 (GRUB_PE32_SECTION_ALIGNMENT);
  o->file_alignment = grub_cpu_to_le32 (GRUB_PE32_FILE_ALIGNMENT);
  o->image_size = grub_cpu_to_le32 (end_address);
  o->header_size = grub_cpu_to_le32 (text_address);
  o->subsystem = grub_cpu_to_le16 (GRUB_PE32_SUBSYSTEM_EFI_APPLICATION);
  
  /* Do these really matter? */
  o->stack_reserve_size = grub_cpu_to_le32 (0x10000);
  o->stack_commit_size = grub_cpu_to_le32 (0x10000);
  o->heap_reserve_size = grub_cpu_to_le32 (0x10000);
  o->heap_commit_size = grub_cpu_to_le32 (0x10000);

  o->num_data_directories = grub_cpu_to_le32 (GRUB_PE32_NUM_DATA_DIRECTORIES);
  
  o->base_relocation_table.rva = grub_cpu_to_le32 (reloc_address);
  o->base_relocation_table.size = grub_cpu_to_le32 (end_address
						    - reloc_address);

  /* The sections.  */
  memset (&text_section, 0, sizeof (text_section));
  strcpy (text_section.name, ".text");
  text_section.virtual_size = grub_cpu_to_le32 (data_address - text_address);
  text_section.virtual_address = grub_cpu_to_le32 (text_address);
  text_section.raw_data_size = grub_cpu_to_le32 (data_address - text_address);
  text_section.raw_data_offset = grub_cpu_to_le32 (text_address);
  text_section.characteristics = grub_cpu_to_le32 (GRUB_PE32_SCN_CNT_CODE
						   | GRUB_PE32_SCN_MEM_EXECUTE
						   | GRUB_PE32_SCN_MEM_READ);

  memset (&data_section, 0, sizeof (data_section));
  strcpy (data_section.name, ".data");
  data_section.virtual_size = grub_cpu_to_le32 (mods_address - data_address);
  data_section.virtual_address = grub_cpu_to_le32 (data_address);
  data_section.raw_data_size = grub_cpu_to_le32 (mods_address - data_address);
  data_section.raw_data_offset = grub_cpu_to_le32 (data_address);
  data_section.characteristics
    = grub_cpu_to_le32 (GRUB_PE32_SCN_CNT_INITIALIZED_DATA
			| GRUB_PE32_SCN_MEM_READ
			| GRUB_PE32_SCN_MEM_WRITE);

  memset (&mods_section, 0, sizeof (mods_section));
  strcpy (mods_section.name, "mods");
  mods_section.virtual_size = grub_cpu_to_le32 (reloc_address - mods_address);
  mods_section.virtual_address = grub_cpu_to_le32 (mods_address);
  mods_section.raw_data_size = grub_cpu_to_le32 (reloc_address - mods_address);
  mods_section.raw_data_offset = grub_cpu_to_le32 (mods_address);
  mods_section.characteristics
    = grub_cpu_to_le32 (GRUB_PE32_SCN_CNT_INITIALIZED_DATA
			| GRUB_PE32_SCN_MEM_READ
			| GRUB_PE32_SCN_MEM_WRITE);

  memset (&reloc_section, 0, sizeof (reloc_section));
  strcpy (reloc_section.name, ".reloc");
  reloc_section.virtual_size = grub_cpu_to_le32 (end_address - reloc_address);
  reloc_section.virtual_address = grub_cpu_to_le32 (reloc_address);
  reloc_section.raw_data_size = grub_cpu_to_le32 (end_address - reloc_address);
  reloc_section.raw_data_offset = grub_cpu_to_le32 (reloc_address);
  reloc_section.characteristics
    = grub_cpu_to_le32 (GRUB_PE32_SCN_CNT_INITIALIZED_DATA
			| GRUB_PE32_SCN_MEM_DISCARDABLE
			| GRUB_PE32_SCN_MEM_READ);

  /* Write them out.  */
  if (fseek (out, 0, SEEK_SET) < 0)
    grub_util_error ("seek failed");

  if (fwrite (&header, sizeof (header), 1, out) != 1
      || fwrite (&text_section, sizeof (text_section), 1, out) != 1
      || fwrite (&data_section, sizeof (data_section), 1, out) != 1
      || fwrite (&mods_section, sizeof (mods_section), 1, out) != 1
      || fwrite (&reloc_section, sizeof (reloc_section), 1, out) != 1)
    grub_util_error ("write failed");
}

/* Convert an ELF relocatable object into an EFI Application (PE32).  */
void
convert_elf (const char *dir, FILE *out, char *mods[])
{
  char *kernel_image;
  size_t kernel_size;
  const char *strtab;
  Elf32_Ehdr *e;
  Elf32_Shdr *sections;
  Elf32_Off section_offset;
  Elf32_Half section_entsize;
  Elf32_Half num_sections;
  Elf32_Addr *section_addresses;
  Elf32_Shdr *symtab_section;
  Elf32_Addr start_address;
  Elf32_Addr text_address, data_address, reloc_address, mods_address;
  Elf32_Addr end_address;

  /* Get the kernel image and check the format.  */
  kernel_image = read_kernel_module (dir, &kernel_size);
  e = (Elf32_Ehdr *) kernel_image;
  if (! check_elf_header (e, kernel_size))
    grub_util_error ("invalid ELF header");
  
  section_offset = grub_cpu_to_le32 (e->e_shoff);
  section_entsize = grub_cpu_to_le16 (e->e_shentsize);
  num_sections = grub_cpu_to_le16 (e->e_shnum);
  if (kernel_size < section_offset + section_entsize * num_sections)
    grub_util_error ("invalid ELF format");

  sections = (Elf32_Shdr *) (kernel_image + section_offset);
  strtab = find_strtab (e, sections, section_entsize);

  /* Relocate sections then symbols in the virtual address space.  */
  section_addresses = locate_sections (sections, section_entsize,
				       num_sections, strtab);
  
  symtab_section = find_symtab_section (sections,
					section_entsize, num_sections);
  if (! symtab_section)
    grub_util_error ("no symbol table");
  
  start_address = relocate_symbols (e, sections, symtab_section,
				    section_addresses, section_entsize,
				    num_sections);
  if (start_address == 0)
    grub_util_error ("start symbol is not defined");

  /* Resolve addresses in the virtual address space.  */
  relocate_addresses (e, sections, section_addresses, section_entsize,
		      num_sections, strtab);

  /* Generate a PE32 image file. The strategy is to dump binary data first,
     then fill up the header.  */
  text_address = make_header_space (out);
  data_address = write_text_sections (out, text_address, e, sections,
				      section_entsize, num_sections,
				      strtab);
  mods_address = write_data_sections (out, data_address, e, sections,
				      section_entsize, num_sections,
				      strtab);
  reloc_address = make_mods_section (out, mods_address, dir, mods);
  end_address = make_reloc_section (out, reloc_address, e, section_addresses,
				    sections, section_entsize, num_sections,
				    strtab);
  make_header (out, text_address, data_address, mods_address,
	       reloc_address, end_address, start_address);

  /* Clean up.  */
  free (section_addresses);
  free (kernel_image);
}

static struct option options[] =
  {
    {"directory", required_argument, 0, 'd'},
    {"output", required_argument, 0, 'o'},
    {"help", no_argument, 0, 'h'},
    {"version", no_argument, 0, 'V'},
    {"verbose", no_argument, 0, 'v'},
    { 0, 0, 0, 0 }
  };

static void
usage (int status)
{
  if (status)
    fprintf (stderr, "Try ``grub-mkimage --help'' for more information.\n");
  else
    printf ("\
Usage: grub-mkimage -o FILE [OPTION]... [MODULES]\n\
\n\
Make a bootable image of GRUB.\n\
\n\
-d, --directory=DIR     use images and modules under DIR [default=%s]\n\
-o, --output=FILE       output a generated image to FILE\n\
-h, --help              display this message and exit\n\
-V, --version           print version information and exit\n\
-v, --verbose           print verbose messages\n\
\n\
Report bugs to <%s>.\n\
", GRUB_LIBDIR, PACKAGE_BUGREPORT);

  exit (status);
}

int
main (int argc, char *argv[])
{
  FILE *fp;
  char *output = NULL;
  char *dir = NULL;

  progname = "grub-mkimage";

  while (1)
    {
      int c = getopt_long (argc, argv, "d:o:hVv", options, 0);
      if (c == -1)
	break;

      switch (c)
	{
	  case 'd':
	    if (dir)
	      free (dir);
	    dir = xstrdup (optarg);
	    break;
	  case 'h':
	    usage (0);
	    break;
	  case 'o':
	    if (output)
	      free (output);
	    output = xstrdup (optarg);
	    break;
	  case 'V':
	    printf ("grub-mkimage (%s) %s\n", PACKAGE_NAME, PACKAGE_VERSION);
	    return 0;
	  case 'v':
	    verbosity++;
	    break;
	  default:
	    usage (1);
	    break;
	}
  }

  if (! output)
    usage (1);

  fp = fopen (output, "wb");
  if (! fp)
    grub_util_error ("cannot open %s", output);

  convert_elf (dir ? : GRUB_LIBDIR, fp, argv + optind);

  fclose (fp);

  return 0;
}