File-copy from v4.4.100
This is the result of 'cp' from a linux-stable tree with the 'v4.4.100'
tag checked out (commit 26d6298789e695c9f627ce49a7bbd2286405798a) on
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Please refer to that tree for all history prior to this point.
Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/block/partitions/efi.c b/block/partitions/efi.c
new file mode 100644
index 0000000..d26d0d2
--- /dev/null
+++ b/block/partitions/efi.c
@@ -0,0 +1,744 @@
+/************************************************************
+ * 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 August 5th, 2013 Davidlohr Bueso <davidlohr@hp.com>
+ * - detect hybrid MBRs, tighter pMBR checking & cleanups.
+ *
+ * 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/kernel.h>
+#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)
+{
+ uint32_t sz = 0;
+ 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.
+ * Some partitioning programs, nonetheless, choose to set
+ * the size to the maximum 32-bit limitation, disregarding
+ * the disk size.
+ *
+ * Hybrid MBRs do not necessarily comply with this.
+ *
+ * Consider a bad value here to be a warning to support dd'ing
+ * an image from a smaller disk to a larger disk.
+ */
+ if (ret == GPT_MBR_PROTECTIVE) {
+ sz = le32_to_cpu(mbr->partition_record[part].size_in_lba);
+ if (sz != (uint32_t) total_sectors - 1 && sz != 0xFFFFFFFF)
+ pr_debug("GPT: mbr size in lba (%u) different than whole disk (%u).\n",
+ sz, min_t(uint32_t,
+ total_sectors - 1, 0xFFFFFFFF));
+ }
+done:
+ return ret;
+}
+
+/**
+ * read_lba(): Read bytes from disk, starting at given LBA
+ * @state: disk parsed partitions
+ * @lba: the Logical Block Address of the partition table
+ * @buffer: destination buffer
+ * @count: bytes to read
+ *
+ * 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: disk parsed partitions
+ * @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 = (size_t)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: disk parsed partitions
+ * @lba: 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: disk parsed partitions
+ * @lba: logical block address of the GPT header to test
+ * @gpt: GPT header ptr, filled on return.
+ * @ptes: 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, pt_size;
+
+ 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;
+ }
+ if (le64_to_cpu((*gpt)->last_usable_lba) < le64_to_cpu((*gpt)->first_usable_lba)) {
+ pr_debug("GPT: last_usable_lba incorrect: %lld > %lld\n",
+ (unsigned long long)le64_to_cpu((*gpt)->last_usable_lba),
+ (unsigned long long)le64_to_cpu((*gpt)->first_usable_lba));
+ 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;
+ }
+
+ /* Sanity check partition table size */
+ pt_size = (u64)le32_to_cpu((*gpt)->num_partition_entries) *
+ le32_to_cpu((*gpt)->sizeof_partition_entry);
+ if (pt_size > KMALLOC_MAX_SIZE) {
+ pr_debug("GUID Partition Table is too large: %llu > %lu bytes\n",
+ (unsigned long long)pt_size, KMALLOC_MAX_SIZE);
+ 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), pt_size);
+
+ 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:pte to check
+ * @lastlba: 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: primary GPT header
+ * @agpt: alternate GPT header
+ * @lastlba: 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)) {
+ pr_warn("GPT:Primary header LBA != Alt. header alternate_lba\n");
+ pr_warn("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)) {
+ pr_warn("GPT:Primary header alternate_lba != Alt. header my_lba\n");
+ pr_warn("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)) {
+ pr_warn("GPT:first_usable_lbas don't match.\n");
+ pr_warn("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)) {
+ pr_warn("GPT:last_usable_lbas don't match.\n");
+ pr_warn("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)) {
+ pr_warn("GPT:disk_guids don't match.\n");
+ error_found++;
+ }
+ if (le32_to_cpu(pgpt->num_partition_entries) !=
+ le32_to_cpu(agpt->num_partition_entries)) {
+ pr_warn("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)) {
+ pr_warn("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)) {
+ pr_warn("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) {
+ pr_warn("GPT:Primary header thinks Alt. header is not at the end of the disk.\n");
+ pr_warn("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) {
+ pr_warn("GPT:Alternate GPT header not at the end of the disk.\n");
+ pr_warn("GPT:%lld != %lld\n",
+ (unsigned long long)le64_to_cpu(agpt->my_lba),
+ (unsigned long long)lastlba);
+ error_found++;
+ }
+
+ if (error_found)
+ pr_warn("GPT: Use GNU Parted to correct GPT errors.\n");
+ return;
+}
+
+/**
+ * find_valid_gpt() - Search disk for valid GPT headers and PTEs
+ * @state: disk parsed partitions
+ * @gpt: GPT header ptr, filled on return.
+ * @ptes: 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)
+ pr_warn("Alternate GPT is invalid, using primary GPT.\n");
+ return 1;
+ }
+ else if (good_agpt) {
+ *gpt = agpt;
+ *ptes = aptes;
+ kfree(pgpt);
+ kfree(pptes);
+ pr_warn("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: disk parsed partitions
+ *
+ * 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_to_str(&ptes[i].unique_partition_guid, info->uuid);
+
+ /* Naively convert UTF16-LE to 7 bits. */
+ label_max = min(ARRAY_SIZE(info->volname) - 1,
+ ARRAY_SIZE(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;
+}