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

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Message-ID: <20100528062425.GB20365@mcafee.com>
Date:	Fri, 28 May 2010 16:24:26 +1000
From:	David McCullough <david_mccullough@...fee.com>
To:	Mike Frysinger <vapier@...too.org>
CC:	uclinux-dev@...inux.org, David Howells <dhowells@...hat.com>,
	Greg Ungerer <gerg@...inux.org>,
	Paul Mundt <lethal@...ux-sh.org>,
	uclinux-dist-devel@...ckfin.uclinux.org,
	microblaze-uclinux@...e.uq.edu.au, Michal Simek <monstr@...str.eu>,
	linux-m32r@...linux-m32r.org,
	Hirokazu Takata <takata@...ux-m32r.org>,
	linux-kernel@...r.kernel.org,
	Yoshinori Sato <ysato@...rs.sourceforge.jp>
Subject: Re: [PATCH 2/2 v2] FLAT: tweak default stack alignment


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@...too.org>

Acked-by: David McCullough <david_mccullough@...fee.com>

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@...fee.com,  Ph:+61 734352815
McAfee - SnapGear      http://www.mcafee.com         http://www.uCdot.org
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