ARM: kprobes: Extend arch_specific_insn to add pointer to emulated instruction

When we come to emulating Thumb instructions then, to interwork
correctly, the code on in the instruction slot must be invoked with a
function pointer which has the least significant bit set. Rather that
set this by hand in every Thumb emulation function we will add a new
field for this purpose to arch_specific_insn, called insn_fn.

This also enables us to seamlessly share emulation functions between ARM
and Thumb code.

Signed-off-by: Jon Medhurst <tixy@yxit.co.uk>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
diff --git a/arch/arm/include/asm/kprobes.h b/arch/arm/include/asm/kprobes.h
index 1e9ff56..feec867 100644
--- a/arch/arm/include/asm/kprobes.h
+++ b/arch/arm/include/asm/kprobes.h
@@ -34,6 +34,7 @@
 typedef void (kprobe_insn_handler_t)(struct kprobe *, struct pt_regs *);
 typedef unsigned long (kprobe_check_cc)(unsigned long);
 typedef void (kprobe_insn_singlestep_t)(struct kprobe *, struct pt_regs *);
+typedef void (kprobe_insn_fn_t)(void);
 
 /* Architecture specific copy of original instruction. */
 struct arch_specific_insn {
@@ -41,6 +42,7 @@
 	kprobe_insn_handler_t		*insn_handler;
 	kprobe_check_cc			*insn_check_cc;
 	kprobe_insn_singlestep_t	*insn_singlestep;
+	kprobe_insn_fn_t		*insn_fn;
 };
 
 struct prev_kprobe {