From: David Gibson <david@gibson•dropbear.id.au>
To: Benjamin Herrenschmidt <benh@kernel•crashing.org>
Cc: linuxppc-dev list <linuxppc-dev@ozlabs•org>
Subject: Re: [PATCH] powerpc/mm: Cleanup handling of execute permission v2
Date: Fri, 11 Sep 2009 14:47:24 +1000 [thread overview]
Message-ID: <20090911044724.GA11840@yookeroo.seuss> (raw)
In-Reply-To: <1250658034.4810.9.camel@pasglop>
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@kernel•crashing.org>
Acked-by: David Gibson <david@gibson•dropbear.id.au>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
prev parent reply other threads:[~2009-09-11 4:47 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-19 5:00 [PATCH] powerpc/mm: Cleanup handling of execute permission v2 Benjamin Herrenschmidt
2009-09-11 4:47 ` David Gibson [this message]
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