Subject: Re: [GIT PULL] s390 updates for 2.6.28-rc1
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Reply-To: schwidefsky@de.ibm.com
To: Ingo Molnar <mingo@elte.hu>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>,
       Linus Torvalds <torvalds@linux-foundation.org>, lethal@linux-sh.org,
       paulus@samba.org, benh@kernel.crashing.org,
       Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
       linux-s390@vger.kernel.org, Roland McGrath <roland@redhat.com>
In-Reply-To: <20081027115146.GE5631@elte.hu>
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	 <20081024113724.GA21375@elte.hu> <1225045593.14057.11.camel@localhost>
	 <20081027115146.GE5631@elte.hu>
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Organization: IBM Corporation
Date: Mon, 27 Oct 2008 13:32:29 +0100
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On Mon, 2008-10-27 at 12:51 +0100, Ingo Molnar wrote:
> * Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:
> > On Fri, 2008-10-24 at 13:37 +0200, Ingo Molnar wrote:
> > > * Heiko Carstens <heiko.carstens@de.ibm.com> wrote:
> > > 
> > > > The s390 vdso preparation patch "arch_setup_additional_pages argument" 
> > > > touches other architectures (x86, sh and powerpc):
> > > > 
> > > > arch_setup_additional_pages currently gets two arguments, the binary 
> > > > format descripton and an indication if the process uses an executable 
> > > > stack or not. The second argument is not used by anybody, it could be 
> > > > removed without replacement.
> > > 
> > > hm, this is the first time i've seen this change,
> > 
> > The code is relatively new and I planned it for the merge window for 
> > 2.6.29. I still have to nag our performance team to do some tests 
> > with it.
> 
> okay, then i'm confused, the subject line says v2.6.28:
> 
>     [GIT PULL] s390 updates for 2.6.28-rc1
> 
> (i have still no objections to those small x86 bits.)

Yeah, that was a misunderstanding between Heiko and me. I planned it for
2.6.29 and didn't tell him about it before I left for vacation. Heiko
just went ahead and added it the 2.6.28-rc1 pull request.

> > >  #define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1
> > >  extern int arch_setup_additional_pages(struct linux_binprm *bprm,
> > > -                                      int executable_stack);
> > > +                                      int uses_interp);
> > > 
> > > why didnt you just add a new uses_interp argument?
> > 
> > I could have but I noticed at the same time that executable_stack is 
> > unused. If somebody finds a need for the executable_stack argument 
> > it can easily re-added but I can't think of a use for it. Ergo I 
> > removed it.
> > 
> > > executable_stack is passed in to potentially enable architectures 
> > > to be aware of how conservative/legacy the address-space of the 
> > > binary is - whether to randomize the vdso, etc. exec-shield used 
> > > to take advantage of that.
> > 
> > What has address space layout / randomization to do with 
> > executable_stack? You lost me there.
> 
> it's just a historic/quirky connection (non-executable stack was the 
> first and biggest step towards a more flexible address space layout) - 
> you were correct to have it cleaned up.

Ok, thanks. Less confused now. 

-- 
blue skies,
  Martin.

"Reality continues to ruin my life." - Calvin.


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