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	 <200907061043.11793.rusty@rustcorp.com.au>
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Date: Wed, 8 Jul 2009 18:31:59 -0400
Message-ID: <817ecb6f0907081531u2f63c3c6y9b1cbc7bf8ff653@mail.gmail.com>
Subject: Re: [PATCH v4] RO/NX protection for loadable kernel modules
From: Siarhei Liakh <sliakh.lkml@gmail.com>
To: Arjan van de Ven <arjan@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.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>, Rusty Russell <rusty@rustcorp.com.au>
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> I like it, you can already put
>
> Acked-by: Arjan van de Ven <arjan@linux.intel.com>

Thanks, I will add this to V5.

...
>> + ? ? ? ? ? ? /*Set text RO if there are still pages between begin
>> and end*/
>> + ? ? ? ? ? ? if (end_addr > begin_addr) {
>> + ? ? ? ? ? ? ? ? ? ? pg_count = PFN_DOWN(end_addr - 1) -
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? PFN_DOWN(begin_addr) + 1;
>> + ? ? ? ? ? ? ? ? ? ? DEBUGP(" ?RO: 0x%lx %lu\n", begin_addr,
>> pg_count);
>> + ? ? ? ? ? ? ? ? ? ? set_memory_ro(begin_addr, pg_count);
>> + ? ? ? ? ? ? } else {
...
> I *think* this can be done as
>
> begin_pfn = PFN_UP( (base);
> end_pfn = PFN_DOWN(base + ro_size);
>
> if (end_pfn > begin_pfn)
> ? ? ? ?set_memory_ro(begin_pfn >> PAGE_SHIFT, end_pfn - begin_pfn);
>
> (note that I think the +1 you have might be buggy)

The +1 is necessary because of (end_addr - 1). However, I like your
way better, so I will incorporate it in V5.
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