On Tue, May 22, 2018 at 2:04 AM, Sam Protsenko semen.protsenko@linaro.org wrote:
In commit e163a931af34 ("cmd: gpt: backup boot code before writing MBR") there was added the procedure for storing old boot code when doing "gpt write". But instead of storing just backup code, the whole MBR was stored, and only specific fields were replaced further, keeping everything else intact. That's obviously not what we want.
Fix the code to actually store only old boot code and zero out everything else. This fixes next testing case:
=> mmc write $loadaddr 0x0 0x7b => gpt write mmc 1 $partitionsIn case when $loadaddr address and further memory contains 0xff, the board was bricked (ROM-code probably didn't like partition entries that were clobbered with 0xff). With this patch applied, commands above don't brick the board.
Tested-by: Andy Shevchenko andy.shevchenko@gmail.com
At least it doesn't break Intel Edison.
Signed-off-by: Sam Protsenko semen.protsenko@linaro.org Cc: Alejandro Hernandez ajhernandez@ti.com
disk/part_efi.c | 6 ++++-- include/part_efi.h | 3 ++- 2 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/disk/part_efi.c b/disk/part_efi.c index 72e3997b84..5c1039f013 100644 --- a/disk/part_efi.c +++ b/disk/part_efi.c @@ -350,8 +350,6 @@ static int set_protective_mbr(struct blk_desc *dev_desc) { /* Setup the Protective MBR */ ALLOC_CACHE_ALIGN_BUFFER_PAD(legacy_mbr, p_mbr, 1, dev_desc->blksz);
memset(p_mbr, 0, sizeof(*p_mbr));if (p_mbr == NULL) { printf("%s: calloc failed!\n", __func__); return -1;@@ -363,6 +361,10 @@ static int set_protective_mbr(struct blk_desc *dev_desc) return -1; }
/* Clear all data in MBR except of backed up boot code */memset((char *)p_mbr + MSDOS_MBR_BOOT_CODE_SIZE, 0, sizeof(*p_mbr) -MSDOS_MBR_BOOT_CODE_SIZE);/* Append signature */ p_mbr->signature = MSDOS_MBR_SIGNATURE; p_mbr->partition_record[0].sys_ind = EFI_PMBR_OSTYPE_EFI_GPT;diff --git a/include/part_efi.h b/include/part_efi.h index 6065c571f3..8525770445 100644 --- a/include/part_efi.h +++ b/include/part_efi.h @@ -20,6 +20,7 @@ #include <efi.h>
#define MSDOS_MBR_SIGNATURE 0xAA55 +#define MSDOS_MBR_BOOT_CODE_SIZE 440 #define EFI_PMBR_OSTYPE_EFI 0xEF #define EFI_PMBR_OSTYPE_EFI_GPT 0xEE
@@ -111,7 +112,7 @@ typedef struct _gpt_entry { } __packed gpt_entry;
typedef struct _legacy_mbr {
u8 boot_code[440];
u8 boot_code[MSDOS_MBR_BOOT_CODE_SIZE]; __le32 unique_mbr_signature; __le16 unknown; struct partition partition_record[4];-- 2.17.0
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