ARM: 8690/1: lpae: build TTB control register value from scratch in v…

…7_ttb_setup

Reading TTBCR in early boot stage might return the value of the previous
kernel's configuration, especially in case of kexec. For example, if
normal kernel (first kernel) had run on a configuration of PHYS_OFFSET <=
PAGE_OFFSET and crash kernel (second kernel) is running on a configuration
PHYS_OFFSET > PAGE_OFFSET, which can happen because it depends on the
reserved area for crash kernel, reading TTBCR and using the value to OR
other bit fields might be risky because it doesn't have a reset value for TTBCR.

Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Hoeun Ryu <hoeun.ryu@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

arch/arm/mm/proc-v7-3level.S

@@ -129,8 +129,7 @@ ENDPROC(cpu_v7_set_pte_ext)
 	.macro	v7_ttb_setup, zero, ttbr0l, ttbr0h, ttbr1, tmp
 	ldr	\tmp, =swapper_pg_dir		@ swapper_pg_dir virtual address
 	cmp	\ttbr1, \tmp, lsr #12		@ PHYS_OFFSET > PAGE_OFFSET?
-	mrc	p15, 0, \tmp, c2, c0, 2		@ TTB control egister
-	orr	\tmp, \tmp, #TTB_EAE
+	mov	\tmp, #TTB_EAE			@ for TTB control egister
 	ALT_SMP(orr	\tmp, \tmp, #TTB_FLAGS_SMP)
 	ALT_UP(orr	\tmp, \tmp, #TTB_FLAGS_UP)
 	ALT_SMP(orr	\tmp, \tmp, #TTB_FLAGS_SMP << 16)