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From: dave.martin@linaro.org (Dave Martin)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: proc-v7: Ensure correct instruction set after cpu_reset
Date: Wed,  3 Oct 2012 10:22:50 +0100	[thread overview]
Message-ID: <1349256170-4367-1-git-send-email-dave.martin@linaro.org> (raw)

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>
---
 arch/arm/mm/proc-v7.S |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index c2e2b66..ca5b575 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
 
-- 
1.7.4.1

             reply	other threads:[~2012-10-03  9:22 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-03  9:22 Dave Martin [this message]
2012-10-03  9:42 ` [PATCH] ARM: proc-v7: Ensure correct instruction set after cpu_reset Will Deacon
2012-10-03 15:04 ` Nicolas Pitre

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