ARM: kprobes: Decode 16-bit Thumb hint instructions

For hints which may have observable effects, like SEV (send event), we
use kprobe_emulate_none which emulates the hint by executing the
original instruction.

For NOP we simulate the instruction using kprobe_simulate_nop, which
does nothing. As probes execute with interrupts disabled this is also
used for hints which may block for an indefinite time, like WFE (wait
for event).

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

arch/arm/kernel/kprobes-common.c

@@ -142,6 +142,15 @@ kprobe_check_cc * const kprobe_condition_checks[16] = {
 };
 
 
+void __kprobes kprobe_simulate_nop(struct kprobe *p, struct pt_regs *regs)
+{
+}
+
+void __kprobes kprobe_emulate_none(struct kprobe *p, struct pt_regs *regs)
+{
+	p->ainsn.insn_fn();
+}
+
 /*
  * Prepare an instruction slot to receive an instruction for emulating.
  * This is done by placing a subroutine return after the location where the