efi.c

linux 内核源代码

		Dprintk
		    ("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) {
		Dprintk("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(bdev);
	if (le64_to_cpu((*gpt)->first_usable_lba) > lastlba) {
		Dprintk("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) {
		Dprintk("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 (!(*ptes = alloc_read_gpt_entries(bdev, *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)) {
		Dprintk("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
 * @bdev
 * @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 block_device *bdev, 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;
	u64 lastlba;
	if (!bdev || !gpt || !ptes)
		return 0;

	lastlba = last_lba(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) {
                        read_lba(bdev, 0, (u8 *) legacymbr,
                                 sizeof (*legacymbr));
                        good_pmbr = is_pmbr_valid(legacymbr);
                        kfree(legacymbr);
                }
                if (!good_pmbr)
                        goto fail;
        }

	good_pgpt = is_gpt_valid(bdev, GPT_PRIMARY_PARTITION_TABLE_LBA,
				 &pgpt, &pptes);
        if (good_pgpt)
		good_agpt = is_gpt_valid(bdev,
					 le64_to_cpu(pgpt->alternate_lba),
					 &agpt, &aptes);
        if (!good_agpt && force_gpt)
                good_agpt = is_gpt_valid(bdev, 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, struct block_device *bdev)
 * @state
 * @bdev
 *
 * 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, struct block_device *bdev)
{
	gpt_header *gpt = NULL;
	gpt_entry *ptes = NULL;
	u32 i;

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

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

	for (i = 0; i < le32_to_cpu(gpt->num_partition_entries) && i < state->limit-1; i++) {
		if (!is_pte_valid(&ptes[i], last_lba(bdev)))
			continue;

		put_partition(state, i+1, le64_to_cpu(ptes[i].starting_lba),
				 (le64_to_cpu(ptes[i].ending_lba) -
                                  le64_to_cpu(ptes[i].starting_lba) +
				  1ULL));

		/* 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 = 1;
	}
	kfree(ptes);
	kfree(gpt);
	printk("\n");
	return 1;
}