ARM: 7180/1: Change kprobes testcase with unpredictable STRD instruction

There is a kprobes testcase for the instruction "strd r2, [r3], r4".
This has unpredictable behaviour as it uses r3 for register writeback
addressing and also stores it to memory.

On a cortex A9, this testcase would fail because the instruction writes
the updated value of r3 to memory, whereas the kprobes emulation code
writes the original value.

Fix this by changing testcase to used r5 instead of r3.

Reported-by: Leif Lindholm <leif.lindholm@arm.com>
Tested-by: Leif Lindholm <leif.lindholm@arm.com>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
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 fc82de8..edf9ad8 100644 (file)
--- a/arch/arm/kernel/kprobes-test-arm.c
+++ b/arch/arm/kernel/kprobes-test-arm.c
@@ -550,7 +550,7 @@ void kprobe_arm_test_cases(void)
        TEST_RPR(  "strccd      r",8, VAL2,", [r",13,0, ", r",12,48,"]")
        TEST_RPR(  "strd        r",4, VAL1,", [r",2, 24,", r",3, 48,"]!")
        TEST_RPR(  "strcsd      r",12,VAL2,", [r",11,48,", -r",10,24,"]!")
-       TEST_RPR(  "strd        r",2, VAL1,", [r",3, 24,"], r",4,48,"")
+       TEST_RPR(  "strd        r",2, VAL1,", [r",5, 24,"], r",4,48,"")
        TEST_RPR(  "strd        r",10,VAL2,", [r",9, 48,"], -r",7,24,"")
        TEST_UNSUPPORTED(".word 0xe1afc0fa      @ strd r12, [pc, r10]!")