linux-kernel - [PATCH 3.10 055/319] ARM: 8618/1: decompressor: reset ttbcr fields to use TTBR0 on ARMv7

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Date:   Sun,  5 Feb 2017 20:20:42 +0100
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Srinivas Ramana <sramana@...eaurora.org>,
        Russell King <rmk+kernel@....linux.org.uk>,
        Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 055/319] ARM: 8618/1: decompressor: reset ttbcr fields to use TTBR0 on ARMv7

From: Srinivas Ramana <sramana@...eaurora.org>

commit 117e5e9c4cfcb7628f08de074fbfefec1bb678b7 upstream.

If the bootloader uses the long descriptor format and jumps to
kernel decompressor code, TTBCR may not be in a right state.
Before enabling the MMU, it is required to clear the TTBCR.PD0
field to use TTBR0 for translation table walks.

The commit dbece45894d3a ("ARM: 7501/1: decompressor:
reset ttbcr for VMSA ARMv7 cores") does the reset of TTBCR.N, but
doesn't consider all the bits for the size of TTBCR.N.

Clear TTBCR.PD0 field and reset all the three bits of TTBCR.N to
indicate the use of TTBR0 and the correct base address width.

Fixes: dbece45894d3 ("ARM: 7501/1: decompressor: reset ttbcr for VMSA ARMv7 cores")
Acked-by: Robin Murphy <robin.murphy@....com>
Signed-off-by: Srinivas Ramana <sramana@...eaurora.org>
Signed-off-by: Russell King <rmk+kernel@....linux.org.uk>
Signed-off-by: Willy Tarreau <w@....eu>
---
 arch/arm/boot/compressed/head.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 032a8d9..9fef67a 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -715,7 +715,7 @@ __armv7_mmu_cache_on:
 		orrne	r0, r0, #1		@ MMU enabled
 		movne	r1, #0xfffffffd		@ domain 0 = client
 		bic     r6, r6, #1 << 31        @ 32-bit translation system
-		bic     r6, r6, #3 << 0         @ use only ttbr0
+		bic     r6, r6, #(7 << 0) | (1 << 4)	@ use only ttbr0
 		mcrne	p15, 0, r3, c2, c0, 0	@ load page table pointer
 		mcrne	p15, 0, r1, c3, c0, 0	@ load domain access control
 		mcrne   p15, 0, r6, c2, c0, 2   @ load ttb control
-- 
2.8.0.rc2.1.gbe9624a