ARM: kprobes: Add hooks to override singlestep()

When a probe fires we must single-step the instruction which was
replaced by a breakpoint. As the steps to do this vary between ARM and
Thumb instructions we need a way to customise single-stepping.

This is done by adding a new hook called insn_singlestep to
arch_specific_insn which is initialised by the instruction decoding
functions.

These single-step hooks must update PC and call the instruction handler.
For Thumb instructions an additional step of updating ITSTATE is needed.
We do this after calling the handler because some handlers will need to
test if they are running in an IT block.

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

1 files changed, 5 insertions, 4 deletions

diff --git a/arch/arm/include/asm/kprobes.h b/arch/arm/include/asm/kprobes.h
index 57d37d52d71..1e9ff56d40c 100644
--- a/arch/arm/include/asm/kprobes.h
+++ b/arch/arm/include/asm/kprobes.h
@@ -32,14 +32,15 @@ typedef u32 kprobe_opcode_t;
 
 struct kprobe;
 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 *);
 
 /* Architecture specific copy of original instruction. */
 struct arch_specific_insn {
-        kprobe_opcode_t         *insn;
-        kprobe_insn_handler_t   *insn_handler;
-        kprobe_check_cc         *insn_check_cc;
+        kprobe_opcode_t                 *insn;
+        kprobe_insn_handler_t           *insn_handler;
+        kprobe_check_cc                 *insn_check_cc;
+        kprobe_insn_singlestep_t        *insn_singlestep;
 };
 
 struct prev_kprobe {