[U-Boot] [PATCH] disk:efi: avoid unaligned access on efi partition

Albert ARIBAUD
2013-10-11T16:00:30Z

Hi Piotr,

On Fri, 11 Oct 2013 15:31:10 +0200, Piotr Wilczek
<p.wilczek@samsung.com> wrote:

> In this patch static variable and memcpy instead of an assignment
> are used to avoid unaligned access exception on some ARM platforms.
>
> Signed-off-by: Piotr Wilczek <p.wilczek@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> CC: Tom Rini <trini@ti.com>
> ---
> disk/part_efi.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/disk/part_efi.c b/disk/part_efi.c
> index b7524d6..303b8af 100644
> --- a/disk/part_efi.c
> +++ b/disk/part_efi.c
> @@ -224,7 +224,8 @@ static int set_protective_mbr(block_dev_desc_t *dev_desc)
> p_mbr->signature = MSDOS_MBR_SIGNATURE;
> p_mbr->partition_record[0].sys_ind = EFI_PMBR_OSTYPE_EFI_GPT;
> p_mbr->partition_record[0].start_sect = 1;
> - p_mbr->partition_record[0].nr_sects = (u32) dev_desc->lba;
> + memcpy(&p_mbr->partition_record[0].nr_sects, &dev_desc->lba,
> + sizeof(dev_desc->lba));
>
> /* Write MBR sector to the MMC device */
> if (dev_desc->block_write(dev_desc->dev, 0, 1, p_mbr) != 1) {
> @@ -387,8 +388,9 @@ int gpt_fill_pte(gpt_header *gpt_h, gpt_entry *gpt_e,
> gpt_e[i].ending_lba = cpu_to_le64(offset - 1);
>
> /* partition type GUID */
> + static efi_guid_t basic_guid = PARTITION_BASIC_DATA_GUID;
> memcpy(gpt_e[i].partition_type_guid.b,
> - &PARTITION_BASIC_DATA_GUID, 16);
> + &basic_guid, 16);

Usually, an all-caps symbol is a macro, which makes taking its address
a no-no.

Besides, doing a memcpy() for 32-bit quantities seems like overkill
for me. Any reason you cannot simply use asm/unaligned.h and either
get_unaligned or put_unaligned depending on where the alignment issue
lies?

> #ifdef CONFIG_PARTITION_UUIDS
> str_uuid = partitions[i].uuid;

Amicalement,
--
Albert.