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/************************************************************
* EFI GUID Partition Table handling
*
* http://www.uefi.org/specs/
* http://www.intel.com/technology/efi/
*
* efi.[ch] by Matt Domsch <Matt_Domsch@dell.com>
* Copyright 2000,2001,2002,2004 Dell Inc.
*
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*
* TODO:
*
* Changelog:
* Mon Nov 09 2004 Matt Domsch <Matt_Domsch@dell.com>
* - test for valid PMBR and valid PGPT before ever reading
* AGPT, allow override with 'gpt' kernel command line option.
* - check for first/last_usable_lba outside of size of disk
*
* Tue Mar 26 2002 Matt Domsch <Matt_Domsch@dell.com>
* - Ported to 2.5.7-pre1 and 2.5.7-dj2
* - Applied patch to avoid fault in alternate header handling
* - cleaned up find_valid_gpt
* - On-disk structure and copy in memory is *always* LE now -
* swab fields as needed
* - remove print_gpt_header()
* - only use first max_p partition entries, to keep the kernel minor number
* and partition numbers tied.
*
* Mon Feb 04 2002 Matt Domsch <Matt_Domsch@dell.com>
* - Removed __PRIPTR_PREFIX - not being used
*
* Mon Jan 14 2002 Matt Domsch <Matt_Domsch@dell.com>
* - Ported to 2.5.2-pre11 + library crc32 patch Linus applied
*
* Thu Dec 6 2001 Matt Domsch <Matt_Domsch@dell.com>
* - Added compare_gpts().
* - moved le_efi_guid_to_cpus() back into this file. GPT is the only
* thing that keeps EFI GUIDs on disk.
* - Changed gpt structure names and members to be simpler and more Linux-like.
*
* Wed Oct 17 2001 Matt Domsch <Matt_Domsch@dell.com>
* - Removed CONFIG_DEVFS_VOLUMES_UUID code entirely per Martin Wilck
*
* Wed Oct 10 2001 Matt Domsch <Matt_Domsch@dell.com>
* - Changed function comments to DocBook style per Andreas Dilger suggestion.
*
* Mon Oct 08 2001 Matt Domsch <Matt_Domsch@dell.com>
* - Change read_lba() to use the page cache per Al Viro's work.
* - print u64s properly on all architectures
* - fixed debug_printk(), now Dprintk()
*
* Mon Oct 01 2001 Matt Domsch <Matt_Domsch@dell.com>
* - Style cleanups
* - made most functions static
* - Endianness addition
* - remove test for second alternate header, as it's not per spec,
* and is unnecessary. There's now a method to read/write the last
* sector of an odd-sized disk from user space. No tools have ever
* been released which used this code, so it's effectively dead.
* - Per Asit Mallick of Intel, added a test for a valid PMBR.
* - Added kernel command line option 'gpt' to override valid PMBR test.
*
* Wed Jun 6 2001 Martin Wilck <Martin.Wilck@Fujitsu-Siemens.com>
* - added devfs volume UUID support (/dev/volumes/uuids) for
* mounting file systems by the partition GUID.
*
* Tue Dec 5 2000 Matt Domsch <Matt_Domsch@dell.com>
* - Moved crc32() to linux/lib, added efi_crc32().
*
* Thu Nov 30 2000 Matt Domsch <Matt_Domsch@dell.com>
* - Replaced Intel's CRC32 function with an equivalent
* non-license-restricted version.
*
* Wed Oct 25 2000 Matt Domsch <Matt_Domsch@dell.com>
* - Fixed the last_lba() call to return the proper last block
*
* Thu Oct 12 2000 Matt Domsch <Matt_Domsch@dell.com>
* - Thanks to Andries Brouwer for his debugging assistance.
* - Code works, detects all the partitions.
*
************************************************************/
#include <linux/crc32.h>
#include <linux/ctype.h>
#include <linux/math64.h>
#include <linux/slab.h>
#include "check.h"
#include "efi.h"
/* This allows a kernel command line option 'gpt' to override
* the test for invalid PMBR. Not __initdata because reloading
* the partition tables happens after init too.
*/
static int force_gpt;
static int __init
force_gpt_fn(char *str)
{
force_gpt = 1;
return 1;
}
__setup("gpt", force_gpt_fn);
/**
* efi_crc32() - EFI version of crc32 function
* @buf: buffer to calculate crc32 of
* @len - length of buf
*
* Description: Returns EFI-style CRC32 value for @buf
*
* This function uses the little endian Ethernet polynomial
* but seeds the function with ~0, and xor's with ~0 at the end.
* Note, the EFI Specification, v1.02, has a reference to
* Dr. Dobbs Journal, May 1994 (actually it's in May 1992).
*/
static inline u32
efi_crc32(const void *buf, unsigned long len)
{
return (crc32(~0L, buf, len) ^ ~0L);
}
/**
* last_lba(): return number of last logical block of device
* @bdev: block device
*
* Description: Returns last LBA value on success, 0 on error.
* This is stored (by sd and ide-geometry) in
* the part[0] entry for this disk, and is the number of
* physical sectors available on the disk.
*/
static u64 last_lba(struct block_device *bdev)
{
if (!bdev || !bdev->bd_inode)
return 0;
return div_u64(bdev->bd_inode->i_size,
bdev_logical_block_size(bdev)) - 1ULL;
}
static inline int
pmbr_part_valid(struct partition *part)
{
if (part->sys_ind == EFI_PMBR_OSTYPE_EFI_GPT &&
le32_to_cpu(part->start_sect) == 1UL)
return 1;
return 0;
}
/**
* is_pmbr_valid(): test Protective MBR for validity
* @mbr: pointer to a legacy mbr structure
*
* Description: Returns 1 if PMBR is valid, 0 otherwise.
* Validity depends on two things:
* 1) MSDOS signature is in the last two bytes of the MBR
* 2) One partition of type 0xEE is found
*/
static int
is_pmbr_valid(legacy_mbr *mbr)
{
int i;
if (!mbr || le16_to_cpu(mbr->signature) != MSDOS_MBR_SIGNATURE)
return 0;
for (i = 0; i < 4; i++)
if (pmbr_part_valid(&mbr->partition_record[i]))
return 1;
return 0;
}
/**
* read_lba(): Read bytes from disk, starting at given LBA
* @state
* @lba
* @buffer
* @size_t
*
* Description: Reads @count bytes from @state->bdev into @buffer.
* Returns number of bytes read on success, 0 on error.
*/
static size_t read_lba(struct parsed_partitions *state,
u64 lba, u8 *buffer, size_t count)
{
size_t totalreadcount = 0;
struct block_device *bdev = state->bdev;
sector_t n = lba * (bdev_logical_block_size(bdev) / 512);
if (!buffer || lba > last_lba(bdev))
return 0;
while (count) {
int copied = 512;
Sector sect;
unsigned char *data = read_part_sector(state, n++, §);
if (!data)
break;
if (copied > count)
copied = count;
memcpy(buffer, data, copied);
put_dev_sector(sect);
buffer += copied;
totalreadcount +=copied;
count -= copied;
}
return totalreadcount;
}
/**
* alloc_read_gpt_entries(): reads partition entries from disk
* @state
* @gpt - GPT header
*
* Description: Returns ptes on success, NULL on error.
* Allocates space for PTEs based on information found in @gpt.
* Notes: remember to free pte when you're done!
*/
static gpt_entry *alloc_read_gpt_entries(struct parsed_partitions *state,
gpt_header *gpt)
{
size_t count;
gpt_entry *pte;
if (!gpt)
return NULL;
count = le32_to_cpu(gpt->num_partition_entries) *
le32_to_cpu(gpt->sizeof_partition_entry);
if (!count)
return NULL;
pte = kzalloc(count, GFP_KERNEL);
if (!pte)
return NULL;
if (read_lba(state, le64_to_cpu(gpt->partition_entry_lba),
(u8 *) pte,
count) < count) {
kfree(pte);
pte=NULL;
return NULL;
}
return pte;
}
/**
* alloc_read_gpt_header(): Allocates GPT header, reads into it from disk
* @state
* @lba is the Logical Block Address of the partition table
*
* Description: returns GPT header on success, NULL on error. Allocates
* and fills a GPT header starting at @ from @state->bdev.
* Note: remember to free gpt when finished with it.
*/
static gpt_header *alloc_read_gpt_header(struct parsed_partitions *state,
u64 lba)
{
gpt_header *gpt;
unsigned ssz = bdev_logical_block_size(state->bdev);
gpt = kzalloc(ssz, GFP_KERNEL);
if (!gpt)
return NULL;
if (read_lba(state, lba, (u8 *) gpt, ssz) < ssz) {
kfree(gpt);
gpt=NULL;
return NULL;
}
return gpt;
}
/**
* is_gpt_valid() - tests one GPT header and PTEs for validity
* @state
* @lba is the logical block address of the GPT header to test
* @gpt is a GPT header ptr, filled on return.
* @ptes is a PTEs ptr, filled on return.
*
* Description: returns 1 if valid, 0 on error.
* If valid, returns pointers to newly allocated GPT header and PTEs.
*/
static int is_gpt_valid(struct parsed_partitions *state, u64 lba,
gpt_header **gpt, gpt_entry **ptes)
{
u32 crc, origcrc;
u64 lastlba;
if (!ptes)
return 0;
if (!(*gpt = alloc_read_gpt_header(state, lba)))
return 0;
/* Check the GUID Partition Table signature */
if (le64_to_cpu((*gpt)->signature) != GPT_HEADER_SIGNATURE) {
pr_debug("GUID Partition Table Header signature is wrong:"
"%lld != %lld\n",
|