diff options
| -rw-r--r-- | block/partitions/efi.c | 74 | ||||
| -rw-r--r-- | block/partitions/efi.h | 3 |
2 files changed, 56 insertions, 21 deletions
diff --git a/block/partitions/efi.c b/block/partitions/efi.c index 1b499dc..e3cb4f1 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 e645ecb..7fef625 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 |