ARM: kprobes: Eliminate test code's use of BX instruction on ARMv4 CPUs

Non-T variants of ARMv4 CPUs don't support the BX instruction so
eliminate its use.

Signed-off-by: Jon Medhurst <tixy@linaro.org>

2 files changed, 10 insertions, 3 deletions

diff --git a/arch/arm/probes/kprobes/test-arm.c b/arch/arm/probes/kprobes/test-arm.c
index e72b07e8cd9a..8866aedfdea2 100644
--- a/arch/arm/probes/kprobes/test-arm.c
+++ b/arch/arm/probes/kprobes/test-arm.c
@@ -215,9 +215,12 @@ void kprobe_arm_test_cases(void)
         TEST_UNSUPPORTED("msr   cpsr_f, lr")
         TEST_UNSUPPORTED("msr   spsr, r0")
 
+#if __LINUX_ARM_ARCH__ >= 5 || \
+    (__LINUX_ARM_ARCH__ == 4 && !defined(CONFIG_CPU_32v4))
         TEST_BF_R("bx   r",0,2f,"")
         TEST_BB_R("bx   r",7,2f,"")
         TEST_BF_R("bxeq r",14,2f,"")
+#endif
 
 #if __LINUX_ARM_ARCH__ >= 5
         TEST_R("clz     r0, r",0, 0x0,"")
diff --git a/arch/arm/probes/kprobes/test-core.c b/arch/arm/probes/kprobes/test-core.c
index e495127d7571..9775de22e2ff 100644
--- a/arch/arm/probes/kprobes/test-core.c
+++ b/arch/arm/probes/kprobes/test-core.c
@@ -236,6 +236,8 @@ static int tests_failed;
 
 #ifndef CONFIG_THUMB2_KERNEL
 
+#define RET(reg)        "mov    pc, "#reg
+
 long arm_func(long r0, long r1);
 
 static void __used __naked __arm_kprobes_test_func(void)
@@ -245,7 +247,7 @@ static void __used __naked __arm_kprobes_test_func(void)
                 ".type arm_func, %%function             \n\t"
                 "arm_func:                              \n\t"
                 "adds   r0, r0, r1                      \n\t"
-                "bx     lr                              \n\t"
+                "mov    pc, lr                          \n\t"
                 ".code "NORMAL_ISA       /* Back to Thumb if necessary */
                 : : : "r0", "r1", "cc"
         );
@@ -253,6 +255,8 @@ static void __used __naked __arm_kprobes_test_func(void)
 
 #else /* CONFIG_THUMB2_KERNEL */
 
+#define RET(reg)        "bx     "#reg
+
 long thumb16_func(long r0, long r1);
 long thumb32even_func(long r0, long r1);
 long thumb32odd_func(long r0, long r1);
@@ -494,7 +498,7 @@ static void __naked benchmark_nop(void)
 {
         __asm__ __volatile__ (
                 "nop            \n\t"
-                "bx     lr"
+                RET(lr)"        \n\t"
         );
 }
 
@@ -977,7 +981,7 @@ void __naked __kprobes_test_case_start(void)
                 "bic    r0, lr, #1  @ r0 = inline data          \n\t"
                 "mov    r1, sp                                  \n\t"
                 "bl     kprobes_test_case_start                 \n\t"
-                "bx     r0                                      \n\t"
+                RET(r0)"                                        \n\t"
         );
 }