On Sun, 2015-07-19 at 11:21 +0900, Masami Hiramatsu wrote: > On 2015/07/16 19:56, Ananth N Mavinakayanahalli wrote: > > Kprobes uses a breakpoint instruction to trap into execution flow > > and the probed instruction is single-stepped from an alternate location. > > > > On some architectures like x86, under certain conditions, the OPTPROBES > > feature enables replacing the probed instruction with a jump instead, > > resulting in a significant perfomance boost (one single-step exception > > is bypassed for each kprobe). > > The OPTPROBE is not only for bypassing the single-step exception, but also > the breakpoint exception. > Please see commit 0dc016dbd820260b (ARM: kprobes: enable OPTPROBES for ARM > 32) too, > which shows how it is done on RISC processor. > > > Powerpc has an in-kernel instruction emulator. Kprobes on powerpc uses > > this emulator already and bypasses the single-step exception, with a > > lot less complexity. > > So, this might miss the point. Since it is impossible to do on some RISC > processor, I agree with this change, but it should be committed with > correct comments.
I don't think it's impossible on powerpc. So we should leave it as a TODO for now. cheers _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
