17.02.2016 22:44, Leif Lindholm пишет:
> Returned from the OpenProtocol operation, the grub_efi_block_io_media
> structure contains the io_align field, specifying the minimum alignment
> required for buffers used in any data transfers with the device.
>
> Make grub_efidisk_readwrite() allocate a temporary buffer, aligned to
> this boundary, if the buffer passed to it does not already meet the
> requirements.
>
> Reported-by: Jeremy Linton <jeremy.lin...@arm.com>
> ---
>
> This modified version is contained entirely within the efidisk driver.
> There is some excessive copying going on, but it removes the risk of
> the changes interfering with other disk drivers.
>
> grub-core/disk/efi/efidisk.c | 37 ++++++++++++++++++++++++++++++++-----
> 1 file changed, 32 insertions(+), 5 deletions(-)
>
> diff --git a/grub-core/disk/efi/efidisk.c b/grub-core/disk/efi/efidisk.c
> index 1c00e3e..901133f 100644
> --- a/grub-core/disk/efi/efidisk.c
> +++ b/grub-core/disk/efi/efidisk.c
> @@ -524,15 +524,42 @@ grub_efidisk_readwrite (struct grub_disk *disk,
> grub_disk_addr_t sector,
> {
> struct grub_efidisk_data *d;
> grub_efi_block_io_t *bio;
> + grub_efi_status_t status;
> + grub_size_t io_align, num_bytes;
> + char *aligned_buf;
>
> d = disk->data;
> bio = d->block_io;
>
> - return efi_call_5 ((wr ? bio->write_blocks : bio->read_blocks), bio,
> - bio->media->media_id,
> - (grub_efi_uint64_t) sector,
> - (grub_efi_uintn_t) size << disk->log_sector_size,
> - buf);
> + /* Set alignment to 1 if 0 specified */
> + io_align = bio->media->io_align ? bio->media->io_align : 1;
We probably should sanity check that it is power of two in
grub_efidisk_open.
> + num_bytes = size << disk->log_sector_size;
> +
> + if ((unsigned long) buf & (io_align - 1))
grub_addr_t?
> + {
> + aligned_buf = grub_memalign (io_align, num_bytes);
> + if (! aligned_buf)
> + return GRUB_EFI_OUT_OF_RESOURCES;
> + if (wr)
> + grub_memcpy (aligned_buf, buf, num_bytes);
> + }
> + else
> + {
> + aligned_buf = buf;
> + }
> +
> + status = efi_call_5 ((wr ? bio->write_blocks : bio->read_blocks), bio,
> + bio->media->media_id, (grub_efi_uint64_t) sector,
> + (grub_efi_uintn_t) num_bytes, aligned_buf);
> +
> + if ((unsigned long) buf & (io_align - 1))
> + {
> + if (!wr)
> + grub_memcpy (buf, aligned_buf, num_bytes);
> + grub_free (aligned_buf);
> + }
> +
> + return status;
> }
>
> static grub_err_t
>
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