From: Wang Nan Date: Fri, 9 Jan 2015 06:37:36 +0000 (+0800) Subject: ARM: kprobes: enable OPTPROBES for ARM 32 X-Git-Tag: fixes-v4.0-rc1~125^2^2~5 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0dc016dbd820260b8ea74337980735b8c88d4ef2;p=pandora-kernel.git 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 Acked-by: Masami Hiramatsu Cc: Will Deacon Reviewed-by: Jon Medhurst (Tixy) Signed-off-by: Jon Medhurst --- Reading git-diff-tree failed