From: Rabin Vincent <rabin.vincent@stericsson.com>
Date: Wed, 4 Jul 2012 06:37:37 +0000 (+0100)
Subject: ARM: 7440/1: kprobes: only test 'sub pc, pc, #1b-2b+8-2' on ARMv6
X-Git-Tag: v3.5-rc6~3^2~2
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=f8b435bb918412c9410da4c4b0b02b6b3d99b27c;p=users%2Fjedix%2Flinux-maple.git

ARM: 7440/1: kprobes: only test 'sub pc, pc, #1b-2b+8-2' on ARMv6

'sub pc, pc, #1b-2b+8-2' results in address<1:0> == '10'.

sub pc, pc, #const (== ADR pc, #const) performs an interworking branch
(BXWritePC()) on ARMv7+ and a simple branch (BranchWritePC()) on earlier
versions.

In ARM state, BXWritePC() is UNPREDICTABLE when address<1:0> == '10'.

In ARM state on ARMv6+, BranchWritePC() ignores address<1:0>.  Before
ARMv6, BranchWritePC() is UNPREDICTABLE if address<1:0> != '00'

So the instruction is UNPREDICTABLE both before and after v6.

Acked-by: Jon Medhurst <tixy@yxit.co.uk>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---

diff --git a/arch/arm/kernel/kprobes-test-arm.c b/arch/arm/kernel/kprobes-test-arm.c
index ba32b393b3f0..38c1a3b103a0 100644
--- a/arch/arm/kernel/kprobes-test-arm.c
+++ b/arch/arm/kernel/kprobes-test-arm.c
@@ -187,8 +187,8 @@ void kprobe_arm_test_cases(void)
 	TEST_BF_R ("mov	pc, r",0,2f,"")
 	TEST_BF_RR("mov	pc, r",0,2f,", asl r",1,0,"")
 	TEST_BB(   "sub	pc, pc, #1b-2b+8")
-#if __LINUX_ARM_ARCH__ >= 6
-	TEST_BB(   "sub	pc, pc, #1b-2b+8-2") /* UNPREDICTABLE before ARMv6 */
+#if __LINUX_ARM_ARCH__ == 6 && !defined(CONFIG_CPU_V7)
+	TEST_BB(   "sub	pc, pc, #1b-2b+8-2") /* UNPREDICTABLE before and after ARMv6 */
 #endif
 	TEST_BB_R( "sub	pc, pc, r",14, 1f-2f+8,"")
 	TEST_BB_R( "rsb	pc, r",14,1f-2f+8,", pc")