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

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Date:	Wed, 26 May 2010 04:45:06 -0400
From:	Mike Frysinger <vapier@...too.org>
To:	uclinux-dev@...inux.org, David Howells <dhowells@...hat.com>,
	David McCullough <davidm@...pgear.com>,
	Greg Ungerer <gerg@...inux.org>,
	Paul Mundt <lethal@...ux-sh.org>
Cc:	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: [PATCH 2/2 v2] FLAT: tweak default stack alignment

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>
---
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

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