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grub/loader/i386/multiboot.c

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/* multiboot.c - boot a multiboot OS image. */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 1999,2000,2001,2002,2003,2004,2005,2007,2008,2009,2010 Free Software Foundation, Inc.
*
* GRUB is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GRUB is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* FIXME: The following features from the Multiboot specification still
* need to be implemented:
* - VBE support
* - symbol table
* - drives table
* - ROM configuration table
* - APM table
*/
/* The bits in the required part of flags field we don't support. */
#define UNSUPPORTED_FLAGS 0x0000fff8
#include <grub/loader.h>
#include <grub/machine/loader.h>
#include <grub/multiboot.h>
#include <grub/cpu/multiboot.h>
#include <grub/elf.h>
#include <grub/aout.h>
#include <grub/file.h>
#include <grub/err.h>
#include <grub/dl.h>
#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/gzio.h>
#include <grub/env.h>
#include <grub/i386/relocator.h>
#include <grub/video.h>
#ifdef GRUB_MACHINE_EFI
#include <grub/efi/efi.h>
#endif
extern grub_dl_t my_mod;
static grub_size_t code_size, alloc_mbi;
char *grub_multiboot_payload_orig;
grub_addr_t grub_multiboot_payload_dest;
grub_size_t grub_multiboot_pure_size;
grub_uint32_t grub_multiboot_payload_eip;
static grub_err_t
grub_multiboot_boot (void)
{
grub_size_t mbi_size;
grub_err_t err;
struct grub_relocator32_state state =
{
.eax = MULTIBOOT_BOOTLOADER_MAGIC,
.ecx = 0,
.edx = 0,
.eip = grub_multiboot_payload_eip,
/* Set esp to some random location in low memory to avoid breaking
non-compliant kernels. */
.esp = 0x7ff00
};
mbi_size = grub_multiboot_get_mbi_size ();
if (alloc_mbi < mbi_size)
{
grub_multiboot_payload_orig
= grub_relocator32_realloc (grub_multiboot_payload_orig,
grub_multiboot_pure_size + mbi_size);
if (!grub_multiboot_payload_orig)
return grub_errno;
alloc_mbi = mbi_size;
}
state.ebx = grub_multiboot_payload_dest + grub_multiboot_pure_size;
err = grub_multiboot_make_mbi (grub_multiboot_payload_orig,
grub_multiboot_payload_dest,
grub_multiboot_pure_size, mbi_size);
if (err)
return err;
#ifdef GRUB_MACHINE_EFI
if (! grub_efi_finish_boot_services ())
grub_fatal ("cannot exit boot services");
#endif
grub_relocator32_boot (grub_multiboot_payload_orig,
grub_multiboot_payload_dest,
state);
/* Not reached. */
return GRUB_ERR_NONE;
}
static grub_err_t
grub_multiboot_unload (void)
{
grub_multiboot_free_mbi ();
grub_relocator32_free (grub_multiboot_payload_orig);
alloc_mbi = 0;
grub_multiboot_payload_orig = NULL;
grub_dl_unref (my_mod);
return GRUB_ERR_NONE;
}
#define MULTIBOOT_LOAD_ELF64
#include "multiboot_elfxx.c"
#undef MULTIBOOT_LOAD_ELF64
#define MULTIBOOT_LOAD_ELF32
#include "multiboot_elfxx.c"
#undef MULTIBOOT_LOAD_ELF32
/* Load ELF32 or ELF64. */
static grub_err_t
grub_multiboot_load_elf (grub_file_t file, void *buffer)
{
if (grub_multiboot_is_elf32 (buffer))
return grub_multiboot_load_elf32 (file, buffer);
else if (grub_multiboot_is_elf64 (buffer))
return grub_multiboot_load_elf64 (file, buffer);
return grub_error (GRUB_ERR_UNKNOWN_OS, "unknown ELF class");
}
void
grub_multiboot (int argc, char *argv[])
{
grub_file_t file = 0;
char buffer[MULTIBOOT_SEARCH];
struct multiboot_header *header;
grub_ssize_t len;
grub_loader_unset ();
if (argc == 0)
{
grub_error (GRUB_ERR_BAD_ARGUMENT, "no kernel specified");
goto fail;
}
file = grub_gzfile_open (argv[0], 1);
if (! file)
{
grub_error (GRUB_ERR_BAD_ARGUMENT, "couldn't open file");
goto fail;
}
len = grub_file_read (file, buffer, MULTIBOOT_SEARCH);
if (len < 32)
{
grub_error (GRUB_ERR_BAD_OS, "file too small");
goto fail;
}
/* Look for the multiboot header in the buffer. The header should
be at least 12 bytes and aligned on a 4-byte boundary. */
for (header = (struct multiboot_header *) buffer;
((char *) header <= buffer + len - 12) || (header = 0);
header = (struct multiboot_header *) ((char *) header + 4))
{
if (header->magic == MULTIBOOT_HEADER_MAGIC
&& !(header->magic + header->flags + header->checksum))
break;
}
if (header == 0)
{
grub_error (GRUB_ERR_BAD_ARGUMENT, "no multiboot header found");
goto fail;
}
if (header->flags & UNSUPPORTED_FLAGS)
{
grub_error (GRUB_ERR_UNKNOWN_OS,
"unsupported flag: 0x%x", header->flags);
goto fail;
}
grub_relocator32_free (grub_multiboot_payload_orig);
grub_multiboot_payload_orig = NULL;
/* Skip filename. */
grub_multiboot_init_mbi (argc - 1, argv + 1);
if (header->flags & MULTIBOOT_AOUT_KLUDGE)
{
int offset = ((char *) header - buffer -
(header->header_addr - header->load_addr));
int load_size = ((header->load_end_addr == 0) ? file->size - offset :
header->load_end_addr - header->load_addr);
if (header->bss_end_addr)
code_size = (header->bss_end_addr - header->load_addr);
else
code_size = load_size;
grub_multiboot_payload_dest = header->load_addr;
grub_multiboot_pure_size += code_size;
/* Allocate a bit more to avoid relocations in most cases. */
alloc_mbi = grub_multiboot_get_mbi_size () + 65536;
grub_multiboot_payload_orig
= grub_relocator32_alloc (grub_multiboot_pure_size + alloc_mbi);
if (! grub_multiboot_payload_orig)
goto fail;
if ((grub_file_seek (file, offset)) == (grub_off_t) -1)
goto fail;
grub_file_read (file, (void *) grub_multiboot_payload_orig, load_size);
if (grub_errno)
goto fail;
if (header->bss_end_addr)
grub_memset ((void *) (grub_multiboot_payload_orig + load_size), 0,
header->bss_end_addr - header->load_addr - load_size);
grub_multiboot_payload_eip = header->entry_addr;
}
else if (grub_multiboot_load_elf (file, buffer) != GRUB_ERR_NONE)
goto fail;
if (header->flags & MULTIBOOT_VIDEO_MODE)
{
switch (header->mode_type)
{
case 1:
grub_env_set ("gfxpayload", "text");
break;
case 0:
{
char *buf;
if (header->depth && header->width && header->height)
buf = grub_xasprintf ("%dx%dx%d,%dx%d,auto", header->width,
header->height, header->depth, header->width,
header->height);
else if (header->width && header->height)
buf = grub_xasprintf ("%dx%d,auto", header->width, header->height);
else
buf = grub_strdup ("auto");
if (!buf)
goto fail;
grub_env_set ("gfxpayload", buf);
grub_free (buf);
break;
}
}
}
grub_multiboot_set_accepts_video (!!(header->flags & MULTIBOOT_VIDEO_MODE));
grub_multiboot_set_bootdev ();
grub_loader_set (grub_multiboot_boot, grub_multiboot_unload, 0);
fail:
if (file)
grub_file_close (file);
if (grub_errno != GRUB_ERR_NONE)
{
grub_relocator32_free (grub_multiboot_payload_orig);
grub_dl_unref (my_mod);
}
}
void
grub_module (int argc, char *argv[])
{
grub_file_t file = 0;
grub_ssize_t size;
char *module = 0;
grub_err_t err;
if (argc == 0)
{
grub_error (GRUB_ERR_BAD_ARGUMENT, "no module specified");
goto fail;
}
if (!grub_multiboot_payload_orig)
{
grub_error (GRUB_ERR_BAD_ARGUMENT,
"you need to load the multiboot kernel first");
goto fail;
}
file = grub_gzfile_open (argv[0], 1);
if (! file)
goto fail;
size = grub_file_size (file);
module = grub_memalign (MULTIBOOT_MOD_ALIGN, size);
if (! module)
goto fail;
err = grub_multiboot_add_module ((grub_addr_t) module, size,
argc - 1, argv + 1);
if (err)
goto fail;
if (grub_file_read (file, module, size) != size)
{
grub_error (GRUB_ERR_FILE_READ_ERROR, "couldn't read file");
goto fail;
}
fail:
if (file)
grub_file_close (file);
}
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