[PATCHv2 2/6] ARM: ftrace: use canonical Thumb-2 wide instruction format

[Rabin Vincent]

As commit 592201a9f15 (ARM: Thumb-2: Support Thumb-2 in undefined
instruction handler) says:

    32-bit Thumb instructions are specified in the form:
        ((first_half << 16 ) | second_half)
    which matches the layout used by the ARM ARM.

Convert the ftrace code to use the same format to avoid the usage of
different formats in kernel code.

Signed-off-by: Rabin Vincent <rabin at rab.in>
---
 arch/arm/kernel/ftrace.c |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index e9488ad..72a381a 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -16,10 +16,11 @@
 #include <linux/uaccess.h>
 
 #include <asm/cacheflush.h>
+#include <asm/opcodes.h>
 #include <asm/ftrace.h>
 
 #ifdef CONFIG_THUMB2_KERNEL
-#define	NOP		0xeb04f85d	/* pop.w {lr} */
+#define	NOP		0xf85deb04	/* pop.w {lr} */
 #else
 #define	NOP		0xe8bd4000	/* pop {lr} */
 #endif
@@ -88,7 +89,7 @@ static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr,
 	if (link)
 		second |= 1 << 14;
 
-	return (second << 16) | first;
+	return __opcode_thumb32_compose(first, second);
 }
 #else
 static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr,
@@ -125,6 +126,14 @@ static int ftrace_modify_code(unsigned long pc, unsigned long old,
 {
 	unsigned long replaced;
 
+	if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
+		old = __opcode_to_mem_thumb32(old);
+		new = __opcode_to_mem_thumb32(new);
+	} else {
+		old = __opcode_to_mem_arm(old);
+		new = __opcode_to_mem_arm(new);
+	}
+
 	if (old) {
 		if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
 			return -EFAULT;
-- 
1.7.8.3