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References: <817ecb6f1002010829m712ffff4hfb64ff3ea236e1f1@mail.gmail.com>
	 <201002020819.55499.rusty@rustcorp.com.au>
Date: Mon, 1 Feb 2010 17:48:16 -0500
Message-ID: <817ecb6f1002011448l7a9d5de4m47bd37f5e8503877@mail.gmail.com>
Subject: Re: [PATCH V9] RO/NX protection for loadable kernel modules
From: Siarhei Liakh <sliakh.lkml@gmail.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org,
       linux-next@vger.kernel.org, Arjan van de Ven <arjan@infradead.org>,
       James Morris <jmorris@namei.org>,
       Andrew Morton <akpm@linux-foundation.org>, Andi Kleen <ak@muc.de>,
       Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>,
       Ingo Molnar <mingo@elte.hu>, Stephen Rothwell <sfr@canb.auug.org.au>,
       Dave Jones <davej@redhat.com>
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> But not compile tested:
[...]
> The casts here should cause a warning.

I did compile it prior to submission and the resulting kernel boots.
However, you are right about the warnings as they scrolled off the
screen when I did not pay attention.
Will fix.

>> + ? ? if (total_size > text_size) {
>> + ? ? ? ? ? ? begin_pfn = PFN_UP((unsigned long)base + text_size);
>> + ? ? ? ? ? ? end_pfn = PFN_UP((unsigned long)base + total_size);
>> + ? ? ? ? ? ? if (end_pfn > begin_pfn)
>> + ? ? ? ? ? ? ? ? ? ? set_memory_nx(begin_pfn << PAGE_SHIFT,
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? end_pfn - begin_pfn);
>
> Use the helper here too?

No, not really. The helper uses PFN_DUWN, and we need PFN_UP here.
This is the only place where I use PFN_UP, so another helper would not
make much sense.

Thanks.
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