ARM: kprobes: Add BLX macro

This is for use by inline assembler which will be added to kprobes-arm.c
It saves memory when used on newer ARM architectures and also provides
correct interworking should ARM probes be required on Thumb kernels in
the future.
Signed-off-by: NJon Medhurst <tixy@yxit.co.uk>
Acked-by: NNicolas Pitre <nicolas.pitre@linaro.org>

arch/arm/kernel/kprobes-arm.c

@@ -67,6 +67,13 @@
 
 #define branch_displacement(insn) sign_extend(((insn) & 0xffffff) << 2, 25)
 
+#if  __LINUX_ARM_ARCH__ >= 6
+#define BLX(reg)	"blx	"reg"		\n\t"
+#else
+#define BLX(reg)	"mov	lr, pc		\n\t"	\
+			"mov	pc, "reg"	\n\t"
+#endif
+
 #define is_r15(insn, bitpos) (((insn) & (0xf << bitpos)) == (0xf << bitpos))
 
 #define PSR_fs	(PSR_f|PSR_s)