From: Dave Martin <dave.martin@linaro.org>
Date: Tue, 16 Oct 2012 10:54:00 +0000 (+0100)
Subject: ARM: 7553/1: proc-v7: Ensure correct instruction set after cpu_reset
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=153cd8e839b5729358d4e5c3371e7509ee5ac96a;p=deliverable%2Flinux.git

ARM: 7553/1: proc-v7: Ensure correct instruction set after cpu_reset

Because mov pc,<Rn> never switches instruction set when executed in
Thumb code, Thumb-2 kernels will silently execute the target code
after cpu_reset as Thumb code, even if the passed code pointer
denotes ARM (bit 0 clear).

This patch uses bx instead, ensuring the correct instruction set
for the target code.

Thumb code in the kernel is not supported prior to ARMv7, so other
CPUs are not affected.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---

diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 846d279f3176..42cc833aa02f 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -57,7 +57,7 @@ ENTRY(cpu_v7_reset)
  THUMB(	bic	r1, r1, #1 << 30 )		@ SCTLR.TE (Thumb exceptions)
 	mcr	p15, 0, r1, c1, c0, 0		@ disable MMU
 	isb
-	mov	pc, r0
+	bx	r0
 ENDPROC(cpu_v7_reset)
 	.popsection