405 -- a little console help, part 2

David Gibson david at gibson.dropbear.id.au
Sat Nov 10 00:53:49 EST 2001

On Fri, Nov 09, 2001 at 06:40:25AM -0700, Mark Pilon wrote:
> David Gibson wrote:
> >
> > Ah, I think I know why this might be - are you using the 2_4_devel
> > tree?
> >
> > All static executables segfaulted before reaching main until very
> > recently: the 4xx's MMU makes it possible to actually enforce the
> > execute permission bit on pages.  Since most processors don't allow
> > this, however, there are heaps of bugs in userland (binutils etc.)
> > where pages aren't marked executable that need to be.  In this case
> > there was instruction just before the got that wasn't marked
> > executable.
> >
> > For now, at least, I've disabled enforcement of the page execute
> > permissions, because there's just too much stuff that breaks with it
> > on.
> What's the fix for this?  It sounds like I want to un-do that change
> enforcing page execute permissions -- David, could you give me
> a spot to look and a suggested patch?  anyone?

I've checked the fix into the latest linuxppc_2_4_devel.  Failing
that, look in do_page_fault() in arch/ppc/mm/fault.c, look for a test
against vma->flags & VM_EXEC, and remove it.

David Gibson			| For every complex problem there is a
david at gibson.dropbear.id.au	| solution which is simple, neat and
				| wrong.  -- H.L. Mencken

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