Re: A question about PROT_NONE on Sparc and Sparc64

Jamie Lokier <[email protected]> Wed, 30 Jun 2004 22:52:20 +0000

Newsgroups	org.kernel.vger.ultralinux,org.kernel.vger.linux-kernel,org.kernel.vger.sparclinux
Message-ID	<[email protected]>

David S. Miller wrote:
> On Wed, 30 Jun 2004 04:28:05 -0400
> Jakub Jelinek <[email protected]> wrote:
> 
> > I believe R!X and X!R pages ought to be possible on sparc64 too,
> > just use a different bit as "read" in the fast ITLB miss handler
> > from the one fast DTLB miss uses.
> 
> That's correct.  But I have no plans to implement this
> any time soon :-)

The PaX security patch already implements R!X pages on Sparc64, so you
could just cut out that part of the patch.  Just pick out the changes
to arch/sparc64/* and include/asm-sparc64/*:

	http://pax.grsecurity.net/pax-linux-2.6.7-200406252135.patch

It appears to use exactly the technique Jakub describes, and has been tested.

-- Jamie