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-rw-r--r--block/partitions/efi.c74
-rw-r--r--block/partitions/efi.h3
2 files changed, 56 insertions, 21 deletions
diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index 1b499dc8fc78..e3cb4f19cf6d 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -158,7 +158,7 @@ static inline int pmbr_part_valid(gpt_mbr_record *part)
if (le32_to_cpu(part->starting_lba) != GPT_PRIMARY_PARTITION_TABLE_LBA)
goto invalid;
- return 1;
+ return GPT_MBR_PROTECTIVE;
invalid:
return 0;
}
@@ -167,21 +167,48 @@ invalid:
* 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:
+ * 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)
+static int is_pmbr_valid(legacy_mbr *mbr)
{
- int i;
+ int i, ret = 0; /* invalid by default */
+
if (!mbr || le16_to_cpu(mbr->signature) != MSDOS_MBR_SIGNATURE)
- return 0;
+ goto done;
+
+ for (i = 0; i < 4; i++) {
+ ret = pmbr_part_valid(&mbr->partition_record[i]);
+ if (ret == GPT_MBR_PROTECTIVE) {
+ /*
+ * 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 (pmbr_part_valid(&mbr->partition_record[i]))
- return 1;
- return 0;
+ if ((mbr->partition_record[i].os_type !=
+ EFI_PMBR_OSTYPE_EFI_GPT) &&
+ (mbr->partition_record[i].os_type != 0x00))
+ ret = GPT_MBR_HYBRID;
+done:
+ return ret;
}
/**
@@ -548,17 +575,22 @@ static int find_valid_gpt(struct parsed_partitions *state, gpt_header **gpt,
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) {
- read_lba(state, 0, (u8 *) legacymbr,
- sizeof (*legacymbr));
- good_pmbr = is_pmbr_valid(legacymbr);
- kfree(legacymbr);
- }
- if (!good_pmbr)
- goto fail;
- }
+ /* 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);
+ 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);
diff --git a/block/partitions/efi.h b/block/partitions/efi.h
index e645ecb35bf3..7fef625c04de 100644
--- a/block/partitions/efi.h
+++ b/block/partitions/efi.h
@@ -37,6 +37,9 @@
#define EFI_PMBR_OSTYPE_EFI 0xEF
#define EFI_PMBR_OSTYPE_EFI_GPT 0xEE
+#define GPT_MBR_PROTECTIVE 1
+#define GPT_MBR_HYBRID 2
+
#define GPT_HEADER_SIGNATURE 0x5452415020494645ULL
#define GPT_HEADER_REVISION_V1 0x00010000
#define GPT_PRIMARY_PARTITION_TABLE_LBA 1