[U-Boot] [PATCH] disk: fix unaligned access in efi partitions

Marc Dietrich
2013-03-29T15:13:47Z

Albert,

On Friday 29 March 2013 13:32:26 Albert ARIBAUD wrote:
> On Fri, 29 Mar 2013 12:28:58 +0100, Marc Dietrich <marvin24@gmx.de> wrote:
> > start_sect is not aligned to a 4 byte boundary thus causing exceptions
> > on ARM platforms. Access this field via the get_unaligned macro.
> >
> > Signed-off-by: Marc Dietrich <marvin24@gmx.de>
> > ---
> >
> > disk/part_efi.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/disk/part_efi.c b/disk/part_efi.c
> > index b3fd0e9..6678a4c 100644
> > --- a/disk/part_efi.c
> > +++ b/disk/part_efi.c
> > @@ -30,6 +30,7 @@
> >
> > *
> > * This limits the maximum size of addressable storage to < 2 Terra Bytes
> > */
> >
> > +#include <asm/unaligned.h>
> >
> > #include <common.h>
> > #include <command.h>
> > #include <ide.h>
> >
> > @@ -505,7 +506,7 @@ err:
> > static int pmbr_part_valid(struct partition *part)
> > {
> >
> > if (part->sys_ind == EFI_PMBR_OSTYPE_EFI_GPT &&
> >
> > - le32_to_cpu(part->start_sect) == 1UL) {
> > + le32_to_cpu(get_unaligned(&part->start_sect)) == 1UL) {
> >
> > return 1;
> >
> > }
>
> Suits me :) but did you not say the same issue was also affecting
> nr_sects?

I checked again and this field is never read - only written to but to an
aligned buffer. So there shouldn't be a problem.

> Also, beside the asm/unaligned.h file I gave as an example, other header
> files in include/linux/unaligned/ exist that provide alignment-related
> macros, notably with _le and _be versions. Maybe you can find one that
> combines the effects of both le32_to_cpu() and get_unaligned()?

I looks like get_unaligned does the job for us already, so we can leave the
le32_to_cpu out. But I cannot test it here because of missing big endian
machine with efi and my two brain halfs are already swapped until confusion
(start_sect is defined as _le32).

Albert, I like to get a fix for this into 2013.04 if possible. Maybe someone
with more endian experience can look at it quickly.

Marc