Re: [PATCH 2/2 v2] FLAT: tweak default stack alignment

From: David McCullough
Date: Fri May 28 2010 - 02:24:47 EST



Jivin Mike Frysinger lays it down ...
> The recent commit 1f0ce8b3dd667dca7 which moved the ARCH_SLAB_MINALIGN
> default into the global header inadvertently broke FLAT for a bunch of
> systems. Blackfin systems now fail on any FLAT exec with:
> Unable to read code+data+bss, errno 14
> When your /init is a FLAT binary, obviously this can be annoying ;).
>
> This stems from the alignment usage in the FLAT loader. The behavior
> before was that FLAT would default to ARCH_SLAB_MINALIGN only if it was
> defined, and this was only defined by arches when they wanted a larger
> alignment value. Otherwise it'd default to pointer alignment. Arguably,
> this is kind of hokey that the FLAT is semi-abusing defines it shouldn't.
>
> But let's ignore that and simply ignore min alignment values of 0.
>
> Signed-off-by: Mike Frysinger <vapier@xxxxxxxxxx>

Acked-by: David McCullough <david_mccullough@xxxxxxxxxx>

Cheers,
Davidm

> ---
> v2
> - split changes & document better
>
> fs/binfmt_flat.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
> index b865622..4959a0a 100644
> --- a/fs/binfmt_flat.c
> +++ b/fs/binfmt_flat.c
> @@ -68,7 +68,7 @@
> * Here we can be a bit looser than the data sections since this
> * needs to only meet arch ABI requirements.
> */
> -#ifdef ARCH_SLAB_MINALIGN
> +#if defined(ARCH_SLAB_MINALIGN) && ARCH_SLAB_MINALIGN != 0
> #define FLAT_STACK_ALIGN (ARCH_SLAB_MINALIGN)
> #else
> #define FLAT_STACK_ALIGN (sizeof(void *))
> --
> 1.7.1
>
>
>

--
David McCullough, david_mccullough@xxxxxxxxxx, Ph:+61 734352815
McAfee - SnapGear http://www.mcafee.com http://www.uCdot.org
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