linux-kernel - Re: [PATCH v5] RO/NX protection for loadable kernel modules

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Message-Id: <200907121928.28887.rusty@rustcorp.com.au>
Date:	Sun, 12 Jul 2009 19:28:27 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Siarhei Liakh <sliakh.lkml@...il.com>,
	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	James Morris <jmorris@...ei.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andi Kleen <ak@....de>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, linux-cris-kernel@...s.com
Subject: Re: [PATCH v5] RO/NX protection for loadable kernel modules

On Sun, 12 Jul 2009 05:15:24 pm Arjan van de Ven wrote:
> Rusty Russell <rusty@...tcorp.com.au> wrote:
> > (I like the idea of trying kmalloc and falling back, simply because
> > it reduces TLB pressure, but that's probably best done after
> > unification).
>
> or using a non-power-of-two get_free_pages() thing...
>
> some architectures will need to know that memory needs to be executable
> at allocation time so that it can be put in an executable address range
> etc...

Yes, maybe that's better than kmalloc.  On my laptop I have 105 modules 
loaded, with 3778464 total length: I'm wasting 206944 bytes on unused tails of 
pages.  But that's only 0.06% of my memory.

Thanks,
Rusty.
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