[PATCH] powerpc/mm: Cleanup handling of execute permission v2

[David Gibson]

On Wed, Aug 19, 2009 at 03:00:34PM +1000, Benjamin Herrenschmidt wrote:
> This is an attempt at cleaning up a bit the way we handle execute
> permission on powerpc. _PAGE_HWEXEC is gone, _PAGE_EXEC is now only
> defined by CPUs that can do something with it, and the myriad of
> #ifdef's in the I$/D$ coherency code is reduced to 2 cases that
> hopefully should cover everything.
> 
> The logic on BookE is a little bit different than what it was though
> not by much. Since now, _PAGE_EXEC will be set by the generic code
> for executable pages, we need to filter out if they are unclean and
> recover it. However, I don't expect the code to be more bloated than
> it already was in that area due to that change.
> 
> I could boast that this brings proper enforcing of per-page execute
> permissions to all BookE and 40x but in fact, we've had that now for
> some time as a side effect of my previous rework in that area (and
> I didn't even know it :-) We would only enable execute permission if
> the page was cache clean and we would only cache clean it if we took
> and exec fault. Since we now enforce that the later only work if
> VM_EXEC is part of the VMA flags, we de-fact already enforce per-page
> execute permissions... Unless I missed something
> 
> Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Acked-by: David Gibson <david at gibson.dropbear.id.au>

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David Gibson			| I'll have my music baroque, and my code
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