ARM: kprobes: enable OPTPROBES for ARM 32
authorWang Nan <wangnan0@huawei.com>
Fri, 9 Jan 2015 06:37:36 +0000 (14:37 +0800)
committerJon Medhurst <tixy@linaro.org>
Tue, 13 Jan 2015 16:10:17 +0000 (16:10 +0000)
commit0dc016dbd820260b8ea74337980735b8c88d4ef2
tree0a6408b4181016d41858afec026cc4e93455f852
parentcbf6ab52add20b845f903decc973afbd5463c527
ARM: kprobes: enable OPTPROBES for ARM 32

This patch introduce kprobeopt for ARM 32.

Limitations:
 - Currently only kernel compiled with ARM ISA is supported.

 - Offset between probe point and optinsn slot must not larger than
   32MiB. Masami Hiramatsu suggests replacing 2 words, it will make
   things complex. Futher patch can make such optimization.

Kprobe opt on ARM is relatively simpler than kprobe opt on x86 because
ARM instruction is always 4 bytes aligned and 4 bytes long. This patch
replace probed instruction by a 'b', branch to trampoline code and then
calls optimized_callback(). optimized_callback() calls opt_pre_handler()
to execute kprobe handler. It also emulate/simulate replaced instruction.

When unregistering kprobe, the deferred manner of unoptimizer may leave
branch instruction before optimizer is called. Different from x86_64,
which only copy the probed insn after optprobe_template_end and
reexecute them, this patch call singlestep to emulate/simulate the insn
directly. Futher patch can optimize this behavior.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Will Deacon <will.deacon@arm.com>
Reviewed-by: Jon Medhurst (Tixy) <tixy@linaro.org>
Signed-off-by: Jon Medhurst <tixy@linaro.org>
arch/arm/Kconfig
arch/arm/include/asm/insn.h [new file with mode: 0644]
arch/arm/include/asm/kprobes.h
arch/arm/kernel/Makefile
arch/arm/kernel/ftrace.c
arch/arm/kernel/insn.h [deleted file]
arch/arm/kernel/jump_label.c
arch/arm/probes/kprobes/Makefile
arch/arm/probes/kprobes/core.c
arch/arm/probes/kprobes/core.h
arch/arm/probes/kprobes/opt-arm.c [new file with mode: 0644]