linux-kernel - Re: [patch -v2] flat: fix data sections alignment

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Date:	Fri, 29 May 2009 12:58:20 +0900
From:	Paul Mundt <lethal@...ux-sh.org>
To:	John Williams <jwilliams@...e.uq.edu.au>
Cc:	Johannes Weiner <jw@...ix.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Howells <dhowells@...hat.com>,
	Russell King <rmk@....linux.org.uk>,
	Bryan Wu <cooloney@...nel.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Greg Ungerer <gerg@...inux.org>, linux-kernel@...r.kernel.org,
	michal.simek@...alogix.com
Subject: Re: [patch -v2] flat: fix data sections alignment

On Fri, May 29, 2009 at 10:01:51AM +1000, John Williams wrote:
> Hi,
> 
> On Wed, Mar 4, 2009 at 11:51 PM, Johannes Weiner <jw@...ix.com> wrote:
> > From: Oskar Schirmer <os@...ix.com>
> >
> > The flat loader uses an architecture's flat_stack_align() to align the
> > stack but assumes word-alignment is enough for the data sections.
> >
> > However, on the Xtensa S6000 we have registers up to 128bit width
> > which can be used from userspace and therefor need userspace stack and
> > data-section alignment of at least this size.
> >
> > This patch drops flat_stack_align() and uses the same alignment that
> > is required for slab caches, ARCH_SLAB_MINALIGN, or wordsize if it's
> > not defined by the architecture.
> >
> > It also fixes m32r which was obviously kaput, aligning an
> > uninitialized stack entry instead of the stack pointer.
> >
> 
> > ---
> > ?arch/arm/include/asm/flat.h ? ? ?| ? ?3 ---
> > ?arch/blackfin/include/asm/flat.h | ? ?1 -
> > ?arch/h8300/include/asm/flat.h ? ?| ? ?1 -
> > ?arch/m68k/include/asm/flat.h ? ? | ? ?1 -
> > ?arch/sh/include/asm/flat.h ? ? ? | ? ?1 -
> > ?fs/binfmt_flat.c ? ? ? ? ? ? ? ? | ? 37 ++++++++++++++++++++++---------------
> > ?include/asm-m32r/flat.h ? ? ? ? ?| ? ?1 -
> > ?7 files changed, 22 insertions(+), 23 deletions(-)
> 
> Can you please cross-check this patch for MicroBlaze as well, we are
> another active nommu architecture.
> 
I already did, see http://lkml.org/lkml/2009/5/27/753

You just need to kill off your flat_stack_align(), as it doesn't do
anything presently it is harmless one way or the other.
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