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: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/arm/kernel/kprobes-arm.c b/arch/arm/kernel/kprobes-arm.c
index ea96214ef341..80a941100f8c 100644
--- a/arch/arm/kernel/kprobes-arm.c
+++ b/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)