linux-kernel - Re: [PATCH] NX protection for kernel data : fix 32 bits S3 suspend

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Message-ID: <20110201080223.GB20372@elte.hu>
Date:	Tue, 1 Feb 2011 09:02:23 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	matthieu castet <castet.matthieu@...e.fr>
Cc:	Linux Kernel list <linux-kernel@...r.kernel.org>,
	linux-security-module@...r.kernel.org,
	Matthias Hopf <mhopf@...e.de>, rjw@...k.pl,
	Andrew Morton <akpm@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] NX protection for kernel data : fix 32 bits S3 suspend


* matthieu castet <castet.matthieu@...e.fr> wrote:

>  static inline int is_kernel_text(unsigned long addr)
>  {
> +#if defined(CONFIG_X86_32) && defined(CONFIG_ACPI_SLEEP)
> +	/*
> +	 * We need to make the wakeup trampoline in first 1MB !NX
> +	 */
> +	if (addr >= PAGE_OFFSET && addr <= (PAGE_OFFSET + (1<<20)))
> +		return 1;
> +#endif

That's pretty ugly. Why not use set_memory_x()/set_memory_nx(), and only for the 
trampoline itself? Does the whole 1MB need to be marked X?

Same goes for the Xen fix.

Thanks,

	Ingo
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