Re: [GIT PULL] s390 updates for 2.6.28-rc1

[Martin Schwidefsky <schwidefsky@de.ibm.com>]

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.