boot.c

i386的bootloader源码grub

		printf (", C");

	      printf (", data=0x%x", data_len);

	      if ((grub_read ((char *) RAW_ADDR (cur_addr), data_len)
		   != data_len)
		  && !errnum)
		errnum = ERR_EXEC_FORMAT;
	      cur_addr += data_len;
	    }

	  if (!errnum)
	    {
	      memset ((char *) RAW_ADDR (cur_addr), 0, bss_len);
	      cur_addr += bss_len;

	      printf (", bss=0x%x", bss_len);
	    }
	}
      else if (!errnum)
	errnum = ERR_EXEC_FORMAT;

      if (!errnum && pu.aout->a_syms
	  && pu.aout->a_syms < (filemax - filepos))
	{
	  int symtab_err, orig_addr = cur_addr;

	  /* we should align to a 4K boundary here for good measure */
	  if (align_4k)
	    cur_addr = (cur_addr + 0xFFF) & 0xFFFFF000;

	  mbi.syms.a.addr = cur_addr;

	  *((int *) RAW_ADDR (cur_addr)) = pu.aout->a_syms;
	  cur_addr += sizeof (int);
	  
	  printf (", symtab=0x%x", pu.aout->a_syms);

	  if (grub_read ((char *) RAW_ADDR (cur_addr), pu.aout->a_syms)
	      == pu.aout->a_syms)
	    {
	      cur_addr += pu.aout->a_syms;
	      mbi.syms.a.tabsize = pu.aout->a_syms;

	      if (grub_read ((char *) &i, sizeof (int)) == sizeof (int))
		{
		  *((int *) RAW_ADDR (cur_addr)) = i;
		  cur_addr += sizeof (int);

		  mbi.syms.a.strsize = i;

		  i -= sizeof (int);

		  printf (", strtab=0x%x", i);

		  symtab_err = (grub_read ((char *) RAW_ADDR (cur_addr), i)
				!= i);
		  cur_addr += i;
		}
	      else
		symtab_err = 1;
	    }
	  else
	    symtab_err = 1;

	  if (symtab_err)
	    {
	      printf ("(bad)");
	      cur_addr = orig_addr;
	      mbi.syms.a.tabsize = 0;
	      mbi.syms.a.strsize = 0;
	      mbi.syms.a.addr = 0;
	    }
	  else
	    mbi.flags |= MB_INFO_AOUT_SYMS;
	}
    }
  else
    /* ELF executable */
    {
      unsigned loaded = 0, memaddr, memsiz, filesiz;
      Elf32_Phdr *phdr;

      /* reset this to zero for now */
      cur_addr = 0;

      /* scan for program segments */
      for (i = 0; i < pu.elf->e_phnum; i++)
	{
	  phdr = (Elf32_Phdr *)
	    (pu.elf->e_phoff + ((int) buffer)
	     + (pu.elf->e_phentsize * i));
	  if (phdr->p_type == PT_LOAD)
	    {
	      /* offset into file */
	      grub_seek (phdr->p_offset);
	      filesiz = phdr->p_filesz;
	      
	      if (type == KERNEL_TYPE_FREEBSD || type == KERNEL_TYPE_NETBSD)
		memaddr = RAW_ADDR (phdr->p_paddr & 0xFFFFFF);
	      else
		memaddr = RAW_ADDR (phdr->p_paddr);
	      
	      memsiz = phdr->p_memsz;
	      if (memaddr < RAW_ADDR (0x100000))
		errnum = ERR_BELOW_1MB;

	      /* If the memory range contains the entry address, get the
		 physical address here.  */
	      if (type == KERNEL_TYPE_MULTIBOOT
		  && (unsigned) entry_addr >= phdr->p_vaddr
		  && (unsigned) entry_addr < phdr->p_vaddr + memsiz)
		real_entry_addr = (entry_func) ((unsigned) entry_addr
						+ memaddr - phdr->p_vaddr);
		
	      /* make sure we only load what we're supposed to! */
	      if (filesiz > memsiz)
		filesiz = memsiz;
	      /* mark memory as used */
	      if (cur_addr < memaddr + memsiz)
		cur_addr = memaddr + memsiz;
	      printf (", <0x%x:0x%x:0x%x>", memaddr, filesiz,
		      memsiz - filesiz);
	      /* increment number of segments */
	      loaded++;

	      /* load the segment */
	      if (memcheck (memaddr, memsiz)
		  && grub_read ((char *) memaddr, filesiz) == filesiz)
		{
		  if (memsiz > filesiz)
		    memset ((char *) (memaddr + filesiz), 0, memsiz - filesiz);
		}
	      else
		break;
	    }
	}

      if (! errnum)
	{
	  if (! loaded)
	    errnum = ERR_EXEC_FORMAT;
	  else
	    {
	      /* Load ELF symbols.  */
	      Elf32_Shdr *shdr = NULL;
	      int tab_size, sec_size;
	      int symtab_err = 0;

	      mbi.syms.e.num = pu.elf->e_shnum;
	      mbi.syms.e.size = pu.elf->e_shentsize;
	      mbi.syms.e.shndx = pu.elf->e_shstrndx;
	      
	      /* We should align to a 4K boundary here for good measure.  */
	      if (align_4k)
		cur_addr = (cur_addr + 0xFFF) & 0xFFFFF000;
	      
	      tab_size = pu.elf->e_shentsize * pu.elf->e_shnum;
	      
	      grub_seek (pu.elf->e_shoff);
	      if (grub_read ((char *) RAW_ADDR (cur_addr), tab_size)
		  == tab_size)
		{
		  mbi.syms.e.addr = cur_addr;
		  shdr = (Elf32_Shdr *) mbi.syms.e.addr;
		  cur_addr += tab_size;
		  
		  printf (", shtab=0x%x", cur_addr);
  		  
		  for (i = 0; i < mbi.syms.e.num; i++)
		    {
		      /* This section is a loaded section,
			 so we don't care.  */
		      if (shdr[i].sh_addr != 0)
			continue;
		      
		      /* This section is empty, so we don't care.  */
		      if (shdr[i].sh_size == 0)
			continue;
		      
		      /* Align the section to a sh_addralign bits boundary.  */
		      cur_addr = ((cur_addr + shdr[i].sh_addralign) & 
				  - (int) shdr[i].sh_addralign);
		      
		      grub_seek (shdr[i].sh_offset);
		      
		      sec_size = shdr[i].sh_size;

		      if (! (memcheck (cur_addr, sec_size)
			     && (grub_read ((char *) RAW_ADDR (cur_addr),
					    sec_size)
				 == sec_size)))
			{
			  symtab_err = 1;
			  break;
			}
		      
		      shdr[i].sh_addr = cur_addr;
		      cur_addr += sec_size;
		    }
		}
	      else 
		symtab_err = 1;
	      
	      if (mbi.syms.e.addr < RAW_ADDR(0x10000))
		symtab_err = 1;
	      
	      if (symtab_err) 
		{
		  printf ("(bad)");
		  mbi.syms.e.num = 0;
		  mbi.syms.e.size = 0;
		  mbi.syms.e.addr = 0;
		  mbi.syms.e.shndx = 0;
		  cur_addr = 0;
		}
	      else
		mbi.flags |= MB_INFO_ELF_SHDR;
	    }
	}
    }

  if (! errnum)
    {
      grub_printf (", entry=0x%x]\n", (unsigned) entry_addr);
      
      /* If the entry address is physically different from that of the ELF
	 header, correct it here.  */
      if (real_entry_addr)
	entry_addr = real_entry_addr;
    }
  else
    {
      putchar ('\n');
      type = KERNEL_TYPE_NONE;
    }

  grub_close ();

  /* Sanity check.  */
  if (suggested_type != KERNEL_TYPE_NONE && suggested_type != type)
    {
      errnum = ERR_EXEC_FORMAT;
      return KERNEL_TYPE_NONE;
    }
  
  return type;
}

int
load_module (char *module, char *arg)
{
  int len;

  /* if we are supposed to load on 4K boundaries */
  cur_addr = (cur_addr + 0xFFF) & 0xFFFFF000;

  if (!grub_open (module))
    return 0;

  len = grub_read ((char *) cur_addr, -1);
  if (! len)
    {
      grub_close ();
      return 0;
    }

  printf ("   [Multiboot-module @ 0x%x, 0x%x bytes]\n", cur_addr, len);

  /* these two simply need to be set if any modules are loaded at all */
  mbi.flags |= MB_INFO_MODS;
  mbi.mods_addr = (int) mll;

  mll[mbi.mods_count].cmdline = (int) arg;
  mll[mbi.mods_count].mod_start = cur_addr;
  cur_addr += len;
  mll[mbi.mods_count].mod_end = cur_addr;
  mll[mbi.mods_count].pad = 0;

  /* increment number of modules included */
  mbi.mods_count++;

  grub_close ();
  return 1;
}

int
load_initrd (char *initrd)
{
  int len;
  unsigned long moveto;
  unsigned long max_addr;
  struct linux_kernel_header *lh
    = (struct linux_kernel_header *) (cur_addr - LINUX_SETUP_MOVE_SIZE);
  
#ifndef NO_DECOMPRESSION
  no_decompression = 1;
#endif
  
  if (! grub_open (initrd))
    goto fail;

  len = grub_read ((char *) cur_addr, -1);
  if (! len)
    {
      grub_close ();
      goto fail;
    }

  if (linux_mem_size)
    moveto = linux_mem_size;
  else
    moveto = (mbi.mem_upper + 0x400) << 10;
  
  moveto = (moveto - len) & 0xfffff000;
  max_addr = (lh->header == LINUX_MAGIC_SIGNATURE && lh->version >= 0x0203
	      ? lh->initrd_addr_max : LINUX_INITRD_MAX_ADDRESS);
  if (moveto + len >= max_addr)
    moveto = (max_addr - len) & 0xfffff000;
  
  /* XXX: Linux 2.3.xx has a bug in the memory range check, so avoid
     the last page.
     XXX: Linux 2.2.xx has a bug in the memory range check, which is
     worse than that of Linux 2.3.xx, so avoid the last 64kb. *sigh*  */
  moveto -= 0x10000;
  memmove ((void *) RAW_ADDR (moveto), (void *) cur_addr, len);

  printf ("   [Linux-initrd @ 0x%x, 0x%x bytes]\n", moveto, len);

  /* FIXME: Should check if the kernel supports INITRD.  */
  lh->ramdisk_image = RAW_ADDR (moveto);
  lh->ramdisk_size = len;

  grub_close ();

 fail:
  
#ifndef NO_DECOMPRESSION
  no_decompression = 0;
#endif

  return ! errnum;
}


#ifdef GRUB_UTIL
/* Dummy function to fake the *BSD boot.  */
static void
bsd_boot_entry (int flags, int bootdev, int sym_start, int sym_end,
		int mem_upper, int mem_lower)
{
  stop ();
}
#endif


/*
 *  All "*_boot" commands depend on the images being loaded into memory
 *  correctly, the variables in this file being set up correctly, and
 *  the root partition being set in the 'saved_drive' and 'saved_partition'
 *  variables.
 */


void
bsd_boot (kernel_t type, int bootdev, char *arg)
{
  char *str;
  int clval = 0, i;
  struct bootinfo bi;

#ifdef GRUB_UTIL
  entry_addr = (entry_func) bsd_boot_entry;
#else
  stop_floppy ();
#endif

  while (*(++arg) && *arg != ' ');
  str = arg;
  while (*str)
    {
      if (*str == '-')
	{
	  while (*str && *str != ' ')
	    {
	      if (*str == 'C')
		clval |= RB_CDROM;
	      if (*str == 'a')
		clval |= RB_ASKNAME;
	      if (*str == 'b')
		clval |= RB_HALT;
	      if (*str == 'c')
		clval |= RB_CONFIG;
	      if (*str == 'd')
		clval |= RB_KDB;
	      if (*str == 'D')
		clval |= RB_MULTIPLE;
	      if (*str == 'g')
		clval |= RB_GDB;
	      if (*str == 'h')
		clval |= RB_SERIAL;
	      if (*str == 'm')
		clval |= RB_MUTE;
	      if (*str == 'r')
		clval |= RB_DFLTROOT;
	      if (*str == 's')
		clval |= RB_SINGLE;
	      if (*str == 'v')
		clval |= RB_VERBOSE;
	      str++;
	    }
	  continue;
	}
      str++;
    }

  if (type == KERNEL_TYPE_FREEBSD)
    {
      clval |= RB_BOOTINFO;

      bi.bi_version = BOOTINFO_VERSION;

      *arg = 0;
      while ((--arg) > (char *) MB_CMDLINE_BUF && *arg != '/');
      if (*arg == '/')
	bi.bi_kernelname = arg + 1;
      else
	bi.bi_kernelname = 0;

      bi.bi_nfs_diskless = 0;
      bi.bi_n_bios_used = 0;	/* this field is apparently unused */

      for (i = 0; i < N_BIOS_GEOM; i++)
	{
	  struct geometry geom;

	  /* XXX Should check the return value.  */
	  get_diskinfo (i + 0x80, &geom);
	  /* FIXME: If HEADS or SECTORS is greater than 255, then this will
	     break the geometry information. That is a drawback of BSD
	     but not of GRUB.  */
	  bi.bi_bios_geom[i] = (((geom.cylinders - 1) << 16)
				+ (((geom.heads - 1) & 0xff) << 8)
				+ (geom.sectors & 0xff));
	}

      bi.bi_size = sizeof (struct bootinfo);
      bi.bi_memsizes_valid = 1;
      bi.bi_bios_dev = saved_drive;
      bi.bi_basemem = mbi.mem_lower;
      bi.bi_extmem = extended_memory;

      if (mbi.flags & MB_INFO_AOUT_SYMS)
	{
	  bi.bi_symtab = mbi.syms.a.addr;
	  bi.bi_esymtab = mbi.syms.a.addr + 4
	    + mbi.syms.a.tabsize + mbi.syms.a.strsize;
	}
#if 0
      else if (mbi.flags & MB_INFO_ELF_SHDR)
	{
	  /* FIXME: Should check if a symbol table exists and, if exists,
	     pass the table to BI.  */
	}
#endif
      else
	{
	  bi.bi_symtab = 0;
	  bi.bi_esymtab = 0;
	}

      /* call entry point */
      (*entry_addr) (clval, bootdev, 0, 0, 0, ((int) (&bi)));
    }
  else
    {
      /*
       *  We now pass the various bootstrap parameters to the loaded
       *  image via the argument list.
       *
       *  This is the official list:
       *
       *  arg0 = 8 (magic)
       *  arg1 = boot flags
       *  arg2 = boot device
       *  arg3 = start of symbol table (0 if not loaded)
       *  arg4 = end of symbol table (0 if not loaded)
       *  arg5 = transfer address from image
       *  arg6 = transfer address for next image pointer
       *  arg7 = conventional memory size (640)
       *  arg8 = extended memory size (8196)
       *
       *  ...in actuality, we just pass the parameters used by the kernel.
       */

      /* call entry point */
      unsigned long end_mark;

      if (mbi.flags & MB_INFO_AOUT_SYMS)
	end_mark = (mbi.syms.a.addr + 4
		    + mbi.syms.a.tabsize + mbi.syms.a.strsize);
      else
	/* FIXME: it should be mbi.syms.e.size.  */
	end_mark = 0;
      
      (*entry_addr) (clval, bootdev, 0, end_mark,
		     extended_memory, mbi.mem_lower);
    }
}