[deliverable/linux.git] / block / partitions / efi.c

/************************************************************
 * 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(gpt_mbr_record *part)
{
        if (part->os_type != EFI_PMBR_OSTYPE_EFI_GPT)
                goto invalid;

        /* set to 0x00000001 (i.e., the LBA of the GPT Partition Header) */
        if (le32_to_cpu(part->starting_lba) != GPT_PRIMARY_PARTITION_TABLE_LBA)
                goto invalid;

        return GPT_MBR_PROTECTIVE;
invalid:
        return 0;
}

/**
 * is_pmbr_valid(): test Protective MBR for validity
 * @mbr: pointer to a legacy mbr structure
 * @total_sectors: amount of sectors in the device
 *
 * Description: Checks for a valid protective or hybrid
 * master boot record (MBR). The validity of a pMBR depends
 * on all of the following properties:
 *  1) MSDOS signature is in the last two bytes of the MBR
 *  2) One partition of type 0xEE is found
 *
 * In addition, a hybrid MBR will have up to three additional
 * primary partitions, which point to the same space that's
 * marked out by up to three GPT partitions.
 *
 * Returns 0 upon invalid MBR, or GPT_MBR_PROTECTIVE or
 * GPT_MBR_HYBRID depending on the device layout.
 */
static int is_pmbr_valid(legacy_mbr *mbr, sector_t total_sectors)
{
        int i, part = 0, ret = 0; /* invalid by default */

        if (!mbr || le16_to_cpu(mbr->signature) != MSDOS_MBR_SIGNATURE)
                goto done;

        for (i = 0; i < 4; i++) {
                ret = pmbr_part_valid(&mbr->partition_record[i]);
                if (ret == GPT_MBR_PROTECTIVE) {
                        part = i;
                        /*
                         * Ok, we at least know that there's a protective MBR,
                         * now check if there are other partition types for
                         * hybrid MBR.
                         */
                        goto check_hybrid;
                }
        }

        if (ret != GPT_MBR_PROTECTIVE)
                goto done;
check_hybrid:
        for (i = 0; i < 4; i++)
                if ((mbr->partition_record[i].os_type !=
                        EFI_PMBR_OSTYPE_EFI_GPT) &&
                    (mbr->partition_record[i].os_type != 0x00))
                        ret = GPT_MBR_HYBRID;

        /*
         * Protective MBRs take up the lesser of the whole disk
         * or 2 TiB (32bit LBA), ignoring the rest of the disk.
         *
         * Hybrid MBRs do not necessarily comply with this.
         */
        if (ret == GPT_MBR_PROTECTIVE) {
                if (le32_to_cpu(mbr->partition_record[part].size_in_lba) !=
                    min((uint32_t) total_sectors - 1, 0xFFFFFFFF))
                        ret = 0;
        }
done:
        return ret;
}

/**
 * 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++, &sect);
                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 = kmalloc(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 = kmalloc(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",
                         (unsigned long long)le64_to_cpu((*gpt)->signature),
                         (unsigned long long)GPT_HEADER_SIGNATURE);
                goto fail;
        }

        /* Check the GUID Partition Table header size is too big */
        if (le32_to_cpu((*gpt)->header_size) >
                        bdev_logical_block_size(state->bdev)) {
                pr_debug("GUID Partition Table Header size is too large: %u > %u\n",
                        le32_to_cpu((*gpt)->header_size),
                        bdev_logical_block_size(state->bdev));
                goto fail;
        }

        /* Check the GUID Partition Table header size is too small */
        if (le32_to_cpu((*gpt)->header_size) < sizeof(gpt_header)) {
                pr_debug("GUID Partition Table Header size is too small: %u < %zu\n",
                        le32_to_cpu((*gpt)->header_size),
                        sizeof(gpt_header));
                goto fail;
        }

        /* Check the GUID Partition Table CRC */
        origcrc = le32_to_cpu((*gpt)->header_crc32);
        (*gpt)->header_crc32 = 0;
        crc = efi_crc32((const unsigned char *) (*gpt), le32_to_cpu((*gpt)->header_size));

        if (crc != origcrc) {
                pr_debug("GUID Partition Table Header CRC is wrong: %x != %x\n",
                         crc, origcrc);
                goto fail;
        }
        (*gpt)->header_crc32 = cpu_to_le32(origcrc);

        /* Check that the my_lba entry points to the LBA that contains
         * the GUID Partition Table */
        if (le64_to_cpu((*gpt)->my_lba) != lba) {
                pr_debug("GPT my_lba incorrect: %lld != %lld\n",
                         (unsigned long long)le64_to_cpu((*gpt)->my_lba),
                         (unsigned long long)lba);
                goto fail;
        }

        /* Check the first_usable_lba and last_usable_lba are
         * within the disk.
         */
        lastlba = last_lba(state->bdev);
        if (le64_to_cpu((*gpt)->first_usable_lba) > lastlba) {
                pr_debug("GPT: first_usable_lba incorrect: %lld > %lld\n",
                         (unsigned long long)le64_to_cpu((*gpt)->first_usable_lba),
                         (unsigned long long)lastlba);
                goto fail;
        }
        if (le64_to_cpu((*gpt)->last_usable_lba) > lastlba) {
                pr_debug("GPT: last_usable_lba incorrect: %lld > %lld\n",
                         (unsigned long long)le64_to_cpu((*gpt)->last_usable_lba),
                         (unsigned long long)lastlba);
                goto fail;
        }

        /* Check that sizeof_partition_entry has the correct value */
        if (le32_to_cpu((*gpt)->sizeof_partition_entry) != sizeof(gpt_entry)) {
                pr_debug("GUID Partitition Entry Size check failed.\n");
                goto fail;
        }

        if (!(*ptes = alloc_read_gpt_entries(state, *gpt)))
                goto fail;

        /* Check the GUID Partition Entry Array CRC */
        crc = efi_crc32((const unsigned char *) (*ptes),
                        le32_to_cpu((*gpt)->num_partition_entries) *
                        le32_to_cpu((*gpt)->sizeof_partition_entry));

        if (crc != le32_to_cpu((*gpt)->partition_entry_array_crc32)) {
                pr_debug("GUID Partitition Entry Array CRC check failed.\n");
                goto fail_ptes;
        }

        /* We're done, all's well */
        return 1;

 fail_ptes:
        kfree(*ptes);
        *ptes = NULL;
 fail:
        kfree(*gpt);
        *gpt = NULL;
        return 0;
}

/**
 * is_pte_valid() - tests one PTE for validity
 * @pte is the pte to check
 * @lastlba is last lba of the disk
 *
 * Description: returns 1 if valid,  0 on error.
 */
static inline int
is_pte_valid(const gpt_entry *pte, const u64 lastlba)
{
        if ((!efi_guidcmp(pte->partition_type_guid, NULL_GUID)) ||
            le64_to_cpu(pte->starting_lba) > lastlba         ||
            le64_to_cpu(pte->ending_lba)   > lastlba)
                return 0;
        return 1;
}

/**
 * compare_gpts() - Search disk for valid GPT headers and PTEs
 * @pgpt is the primary GPT header
 * @agpt is the alternate GPT header
 * @lastlba is the last LBA number
 * Description: Returns nothing.  Sanity checks pgpt and agpt fields
 * and prints warnings on discrepancies.
 * 
 */
static void
compare_gpts(gpt_header *pgpt, gpt_header *agpt, u64 lastlba)
{
        int error_found = 0;
        if (!pgpt || !agpt)
                return;
        if (le64_to_cpu(pgpt->my_lba) != le64_to_cpu(agpt->alternate_lba)) {
                printk(KERN_WARNING
                       "GPT:Primary header LBA != Alt. header alternate_lba\n");
                printk(KERN_WARNING "GPT:%lld != %lld\n",
                       (unsigned long long)le64_to_cpu(pgpt->my_lba),
                       (unsigned long long)le64_to_cpu(agpt->alternate_lba));
                error_found++;
        }
        if (le64_to_cpu(pgpt->alternate_lba) != le64_to_cpu(agpt->my_lba)) {
                printk(KERN_WARNING
                       "GPT:Primary header alternate_lba != Alt. header my_lba\n");
                printk(KERN_WARNING "GPT:%lld != %lld\n",
                       (unsigned long long)le64_to_cpu(pgpt->alternate_lba),
                       (unsigned long long)le64_to_cpu(agpt->my_lba));
                error_found++;
        }
        if (le64_to_cpu(pgpt->first_usable_lba) !=
            le64_to_cpu(agpt->first_usable_lba)) {
                printk(KERN_WARNING "GPT:first_usable_lbas don't match.\n");
                printk(KERN_WARNING "GPT:%lld != %lld\n",
                       (unsigned long long)le64_to_cpu(pgpt->first_usable_lba),
                       (unsigned long long)le64_to_cpu(agpt->first_usable_lba));
                error_found++;
        }
        if (le64_to_cpu(pgpt->last_usable_lba) !=
            le64_to_cpu(agpt->last_usable_lba)) {
                printk(KERN_WARNING "GPT:last_usable_lbas don't match.\n");
                printk(KERN_WARNING "GPT:%lld != %lld\n",
                       (unsigned long long)le64_to_cpu(pgpt->last_usable_lba),
                       (unsigned long long)le64_to_cpu(agpt->last_usable_lba));
                error_found++;
        }
        if (efi_guidcmp(pgpt->disk_guid, agpt->disk_guid)) {
                printk(KERN_WARNING "GPT:disk_guids don't match.\n");
                error_found++;
        }
        if (le32_to_cpu(pgpt->num_partition_entries) !=
            le32_to_cpu(agpt->num_partition_entries)) {
                printk(KERN_WARNING "GPT:num_partition_entries don't match: "
                       "0x%x != 0x%x\n",
                       le32_to_cpu(pgpt->num_partition_entries),
                       le32_to_cpu(agpt->num_partition_entries));
                error_found++;
        }
        if (le32_to_cpu(pgpt->sizeof_partition_entry) !=
            le32_to_cpu(agpt->sizeof_partition_entry)) {
                printk(KERN_WARNING
                       "GPT:sizeof_partition_entry values don't match: "
                       "0x%x != 0x%x\n",
                       le32_to_cpu(pgpt->sizeof_partition_entry),
                       le32_to_cpu(agpt->sizeof_partition_entry));
                error_found++;
        }
        if (le32_to_cpu(pgpt->partition_entry_array_crc32) !=
            le32_to_cpu(agpt->partition_entry_array_crc32)) {
                printk(KERN_WARNING
                       "GPT:partition_entry_array_crc32 values don't match: "
                       "0x%x != 0x%x\n",
                       le32_to_cpu(pgpt->partition_entry_array_crc32),
                       le32_to_cpu(agpt->partition_entry_array_crc32));
                error_found++;
        }
        if (le64_to_cpu(pgpt->alternate_lba) != lastlba) {
                printk(KERN_WARNING
                       "GPT:Primary header thinks Alt. header is not at the end of the disk.\n");
                printk(KERN_WARNING "GPT:%lld != %lld\n",
                        (unsigned long long)le64_to_cpu(pgpt->alternate_lba),
                        (unsigned long long)lastlba);
                error_found++;
        }

        if (le64_to_cpu(agpt->my_lba) != lastlba) {
                printk(KERN_WARNING
                       "GPT:Alternate GPT header not at the end of the disk.\n");
                printk(KERN_WARNING "GPT:%lld != %lld\n",
                        (unsigned long long)le64_to_cpu(agpt->my_lba),
                        (unsigned long long)lastlba);
                error_found++;
        }

        if (error_found)
                printk(KERN_WARNING
                       "GPT: Use GNU Parted to correct GPT errors.\n");
        return;
}

/**
 * find_valid_gpt() - Search disk for valid GPT headers and PTEs
 * @state
 * @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.
 * Validity depends on PMBR being valid (or being overridden by the
 * 'gpt' kernel command line option) and finding either the Primary
 * GPT header and PTEs valid, or the Alternate GPT header and PTEs
 * valid.  If the Primary GPT header is not valid, the Alternate GPT header
 * is not checked unless the 'gpt' kernel command line option is passed.
 * This protects against devices which misreport their size, and forces
 * the user to decide to use the Alternate GPT.
 */
static int find_valid_gpt(struct parsed_partitions *state, gpt_header **gpt,
                          gpt_entry **ptes)
{
        int good_pgpt = 0, good_agpt = 0, good_pmbr = 0;
        gpt_header *pgpt = NULL, *agpt = NULL;
        gpt_entry *pptes = NULL, *aptes = NULL;
        legacy_mbr *legacymbr;
        sector_t total_sectors = i_size_read(state->bdev->bd_inode) >> 9;
        u64 lastlba;

        if (!ptes)
                return 0;

        lastlba = last_lba(state->bdev);
        if (!force_gpt) {
                /* This will be added to the EFI Spec. per Intel after v1.02. */
                legacymbr = kzalloc(sizeof(*legacymbr), GFP_KERNEL);
                if (!legacymbr)
                        goto fail;

                read_lba(state, 0, (u8 *)legacymbr, sizeof(*legacymbr));
                good_pmbr = is_pmbr_valid(legacymbr, total_sectors);
                kfree(legacymbr);

                if (!good_pmbr)
                        goto fail;

                pr_debug("Device has a %s MBR\n",
                         good_pmbr == GPT_MBR_PROTECTIVE ?
                                                "protective" : "hybrid");
        }

        good_pgpt = is_gpt_valid(state, GPT_PRIMARY_PARTITION_TABLE_LBA,
                                 &pgpt, &pptes);
        if (good_pgpt)
                good_agpt = is_gpt_valid(state,
                                         le64_to_cpu(pgpt->alternate_lba),
                                         &agpt, &aptes);
        if (!good_agpt && force_gpt)
                good_agpt = is_gpt_valid(state, lastlba, &agpt, &aptes);

        /* The obviously unsuccessful case */
        if (!good_pgpt && !good_agpt)
                goto fail;

        compare_gpts(pgpt, agpt, lastlba);

        /* The good cases */
        if (good_pgpt) {
                *gpt  = pgpt;
                *ptes = pptes;
                kfree(agpt);
                kfree(aptes);
                if (!good_agpt) {
                        printk(KERN_WARNING 
                               "Alternate GPT is invalid, "
                               "using primary GPT.\n");
                }
                return 1;
        }
        else if (good_agpt) {
                *gpt  = agpt;
                *ptes = aptes;
                kfree(pgpt);
                kfree(pptes);
                printk(KERN_WARNING 
                       "Primary GPT is invalid, using alternate GPT.\n");
                return 1;
        }

 fail:
        kfree(pgpt);
        kfree(agpt);
        kfree(pptes);
        kfree(aptes);
        *gpt = NULL;
        *ptes = NULL;
        return 0;
}

/**
 * efi_partition(struct parsed_partitions *state)
 * @state
 *
 * Description: called from check.c, if the disk contains GPT
 * partitions, sets up partition entries in the kernel.
 *
 * If the first block on the disk is a legacy MBR,
 * it will get handled by msdos_partition().
 * If it's a Protective MBR, we'll handle it here.
 *
 * We do not create a Linux partition for GPT, but
 * only for the actual data partitions.
 * Returns:
 * -1 if unable to read the partition table
 *  0 if this isn't our partition table
 *  1 if successful
 *
 */
int efi_partition(struct parsed_partitions *state)
{
        gpt_header *gpt = NULL;
        gpt_entry *ptes = NULL;
        u32 i;
        unsigned ssz = bdev_logical_block_size(state->bdev) / 512;

        if (!find_valid_gpt(state, &gpt, &ptes) || !gpt || !ptes) {
                kfree(gpt);
                kfree(ptes);
                return 0;
        }

        pr_debug("GUID Partition Table is valid!  Yea!\n");

        for (i = 0; i < le32_to_cpu(gpt->num_partition_entries) && i < state->limit-1; i++) {
                struct partition_meta_info *info;
                unsigned label_count = 0;
                unsigned label_max;
                u64 start = le64_to_cpu(ptes[i].starting_lba);
                u64 size = le64_to_cpu(ptes[i].ending_lba) -
                           le64_to_cpu(ptes[i].starting_lba) + 1ULL;

                if (!is_pte_valid(&ptes[i], last_lba(state->bdev)))
                        continue;

                put_partition(state, i+1, start * ssz, size * ssz);

                /* If this is a RAID volume, tell md */
                if (!efi_guidcmp(ptes[i].partition_type_guid,
                                 PARTITION_LINUX_RAID_GUID))
                        state->parts[i + 1].flags = ADDPART_FLAG_RAID;

                info = &state->parts[i + 1].info;
                efi_guid_unparse(&ptes[i].unique_partition_guid, info->uuid);

                /* Naively convert UTF16-LE to 7 bits. */
                label_max = min(sizeof(info->volname) - 1,
                                sizeof(ptes[i].partition_name));
                info->volname[label_max] = 0;
                while (label_count < label_max) {
                        u8 c = ptes[i].partition_name[label_count] & 0xff;
                        if (c && !isprint(c))
                                c = '!';
                        info->volname[label_count] = c;
                        label_count++;
                }
                state->parts[i + 1].has_info = true;
        }
        kfree(ptes);
        kfree(gpt);
        strlcat(state->pp_buf, "\n", PAGE_SIZE);
        return 1;
}