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

[catalin.marinas@arm.com (Catalin Marinas)]

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@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

Yes.

> and push it to the patch system ?

That's up to Russell.

-- 
Catalin