From: Suresh Siddha <suresh.b.siddha@intel•com>
To: Siarhei Liakh <sliakh.lkml@gmail•com>
Cc: "linux-kernel@vger•kernel.org" <linux-kernel@vger•kernel.org>,
"linux-security-module@vger•kernel.org"
<linux-security-module@vger•kernel.org>,
"linux-next@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>,
Rusty Russell <rusty@rustcorp•com.au>,
Stephen Rothwell <sfr@canb•auug.org.au>,
Dave Jones <davej@redhat•com>
Subject: Re: [PATCH 1/4] [tip:x86/mm] Correcting improper large page preservation
Date: Fri, 02 Apr 2010 23:43:20 -0700 [thread overview]
Message-ID: <1270277000.2686.20.camel@sbs-t61> (raw)
In-Reply-To: <v2o817ecb6f1003311859nb14bab83y80f743a0accc5028@mail.gmail.com>
On Wed, 2010-03-31 at 18:59 -0700, Siarhei Liakh wrote:
> + /*
> + * .data and .bss should always be writable.
> + */
> + if ((within(pfn, __pa((unsigned long)_sdata) >> PAGE_SHIFT,
> + __pa((unsigned long)_edata) >> PAGE_SHIFT)) ||
> + (within(pfn, __pa((unsigned long)__bss_start) >> PAGE_SHIFT,
> + __pa((unsigned long)__bss_stop) >> PAGE_SHIFT))) {
> + pgprot_val(required) |= _PAGE_RW;
> + }
I have reviewed this patch and the only comment I have is:
On 64bit kernels, kernel text/data mapping and kernel identity mappings
are different virtual addresses mapping to same pfn ranges. For the
data/bss pages, does it help (in identifying certain data corruptions
more easily) in making the kernel identity mapping to be set to
read-only and enforce the need of RW only for the kernel data mappings.
Or is there some obscure code that uses something like
__va(__pa(data_symbol)) and writes to it?
If not, we can remove the __pa() constructs above and use the addr for
comparisons.
Otherwise this patch looks good to me.
Reviewed-by: Suresh Siddha <suresh.b.siddha@intel•com>
next prev parent reply other threads:[~2010-04-03 6:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-01 1:59 [PATCH 1/4] [tip:x86/mm] Correcting improper large page preservation Siarhei Liakh
2010-04-03 6:43 ` Suresh Siddha [this message]
2010-04-06 14:51 ` Siarhei Liakh
2010-05-05 18:14 ` Siarhei Liakh
[not found] ` <g2s817ecb6f1005051114kfbf4f33dwf473e0a30e00d614@mail.gmail.com>
2010-05-06 6:19 ` Ingo Molnar
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