linux-kernel - Re: [PATCH] [1/2] CPA: Fix set_memory

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Message-ID: <alpine.LFD.1.00.0802122318090.12988@apollo.tec.linutronix.de>
Date:	Wed, 13 Feb 2008 00:02:53 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Andi Kleen <ak@...e.de>
cc:	ying.huang@...el.com, mingo@...e.hu, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [1/2] CPA: Fix set_memory_x for ioremap v2

On Tue, 12 Feb 2008, Andi Kleen wrote:
> There would be several possible ways to fix this:
> - Simply don't set the NX bit in the original ioremap and drop
> set_memory_x and add a ioremap_exec(). That would be my preferred solution, 
> but unfortunately has been dismissed before
> - Drop all __pas and always use the physical address derived 
> from the looked up PTE. This would need some significant restructuring
> and would only fix the first problem above, not the second.
> - Special case NX clear to change any aliases. I chose this one
> because it happens to fix both problems, so is both a fix
> and a optimization.
> 
> This implies that it's still not safe calling set_memory_(not x) on
> any ioremaped/vmalloced/module addresses. 

There is another option:

- Fix it proper.

The so-called "significant restructuring" took a mere 2 hours,
which is probably less than the time consumed in this thread.

http://git.kernel.org/?p=linux/kernel/git/x86/linux-2.6-x86.git;a=shortlog;h=mm

Thanks,

	tglx
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