arm64: kprobes instruction simulation support

Kprobes needs simulation of instructions that cannot be stepped
from a different memory location, e.g.: those instructions
that uses PC-relative addressing. In simulation, the behaviour
of the instruction is implemented using a copy of pt_regs.

The following instruction categories are simulated:
 - All branching instructions(conditional, register, and immediate)
 - Literal access instructions(load-literal, adr/adrp)

Conditional execution is limited to branching instructions in
ARM v8. If conditions at PSTATE do not match the condition fields
of opcode, the instruction is effectively NOP.

Thanks to Will Cohen for assorted suggested changes.

Signed-off-by: Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com>
Signed-off-by: William Cohen <wcohen@redhat.com>
Signed-off-by: David A. Long <dave.long@linaro.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
[catalin.marinas@arm.com: removed linux/module.h include]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/arm64/include/asm/probes.h b/arch/arm64/include/asm/probes.h
index 1e8a21a96002..5af574d632fa 100644
--- a/arch/arm64/include/asm/probes.h
+++ b/arch/arm64/include/asm/probes.h
@@ -15,17 +15,18 @@
 #ifndef _ARM_PROBES_H
 #define _ARM_PROBES_H
 
+#include <asm/opcodes.h>
+
 struct kprobe;
 struct arch_specific_insn;
 
 typedef u32 kprobe_opcode_t;
-typedef unsigned long (kprobes_pstate_check_t)(unsigned long);
 typedef void (kprobes_handler_t) (u32 opcode, long addr, struct pt_regs *);
 
 /* architecture specific copy of original instruction */
 struct arch_specific_insn {
 	kprobe_opcode_t *insn;
-	kprobes_pstate_check_t *pstate_cc;
+	pstate_check_t *pstate_cc;
 	kprobes_handler_t *handler;
 	/* restore address after step xol */
 	unsigned long restore;