[PATCH] ARM: decompressor: Fix mmu mapping for non-DRAM address space.

[Santosh Shilimkar]

On Tuesday 08 May 2012 07:53 PM, Catalin Marinas wrote:
> On Tue, May 08, 2012 at 03:20:43PM +0100, Santosh Shilimkar wrote:
>> On Tuesday 08 May 2012 07:46 PM, Catalin Marinas wrote:
>>> On Tue, May 08, 2012 at 03:01:57PM +0100, Shilimkar, Santosh wrote:
>>>> From b906ef372f0e2dfa7e1fbc3c87406b1c303d8975 Mon Sep 17 00:00:00 2001
>>>> From: R Sricharan <r.sricharan at ti.com>
>>>> Date: Mon, 7 May 2012 15:11:58 +0530
>>>> Subject: [PATCH] ARM: decompressor: Fix mmu mapping for non-DRAM address
>>>>  space.
>>>>
>>>> ARM decompressor code setups entire 4GB address space pages.
>>>> Out of the 4GB, about 256MB are setup with normal memory attributes
>>>> for needed DRAM and the rest of the address space as Strongly ordered.
>>>>
>>>> But since all the sections are mapped in DOMAIN0(Manager), processor
>>>> like Cortex-A15, can speculatively prefetch from non-DRAM read sensitive
>>>> areas even in the presence of XN(Non-executable). This is because XN
>>>> attribute is ignored when domain is Manager.
>>>>
>>>> This can lead to accesses to non-accessible address regions leading
>>>> to various interconnect violations. The issue is observed on OMAP5.
>>>>
>>>> This patch tries to fix the issue by ensuring that all regions
>>>> are marked as a client domain so that XN attribute is effective.
>>>>
>>>> Signed-off-by: R Sricharan <r.sricharan at ti.com>
>>>> Signed-off-by: Santosh Shilimkar <santosh.shilimkar at ti.com>
>>>> Cc: Russell King <linux at arm.linux.org.uk>
>>>> Cc: Catalin Marinas <catalin.marinas at arm.com>
>>>> ---
>>>>  arch/arm/boot/compressed/head.S |   10 ++++++++--
>>>>  1 files changed, 8 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
>>>> index dc7e8ce..a2602b8 100644
>>>> --- a/arch/arm/boot/compressed/head.S
>>>> +++ b/arch/arm/boot/compressed/head.S
>>>> @@ -578,10 +578,12 @@ __setup_mmu:	sub	r3, r4, #16384		@ Page directory size
>>>>  		mov	r9, r0, lsr #18
>>>>  		mov	r9, r9, lsl #18		@ start of RAM
>>>>  		add	r10, r9, #0x10000000	@ a reasonable RAM size
>>>> -		mov	r1, #0x12
>>>> +		mov	r1, #0x02		@ Default executable section
>>>
>>> I think it is simpler if you leave the original code here (with XN)
>>
>> Sounds good. With that updated can I add your ack
> 
> Yes.
Great. Thanks
> 
>> and push it to the patch system ?
> 
> That's up to Russell.
> 
Ofcourse after Russell's ok.

Regards
Santosh