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

[Santosh Shilimkar <santosh.shilimkar@ti.com>]

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@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@ti.com>
>> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
>> Cc: Russell King <linux@arm.linux.org.uk>
>> Cc: Catalin Marinas <catalin.marinas@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 and push it
to the patch system ?

Regards
Santosh