On Fri, 10 Jan 2020 21:35:12 -0300 [email protected] wrote: > <[email protected]>,Jann Horn <[email protected]>,Thomas Gleixner > <[email protected]>,Tvrtko Ursulin <[email protected]>,Lionel > Landwerlin <[email protected]>,linux-kernel > <[email protected]>,"[email protected]" > <[email protected]>,"[email protected]" > <[email protected]>,"[email protected]" > <[email protected]>,"[email protected]" > <[email protected]>,"[email protected]" > <[email protected]>,"[email protected]" > <[email protected]>,"[email protected]" > <[email protected]>,"[email protected]" > <[email protected]>,"[email protected]" > <[email protected]> > From: Arnaldo Carvalho de Melo <[email protected]> > Message-ID: <[email protected]> > > On January 10, 2020 9:23:27 PM GMT-03:00, Song Liu <[email protected]> > wrote: > > > > > >> On Jan 10, 2020, at 3:47 PM, Masami Hiramatsu <[email protected]> > >wrote: > >> > >> On Fri, 10 Jan 2020 13:45:31 -0300 > >> Arnaldo Carvalho de Melo <[email protected]> wrote: > >> > >>> Em Sat, Jan 11, 2020 at 12:52:13AM +0900, Masami Hiramatsu escreveu: > >>>> On Fri, 10 Jan 2020 15:02:34 +0100 Peter Zijlstra > ><[email protected]> wrote: > >>>>> Again, this only allows attaching to previously created kprobes, > >it does > >>>>> not allow creating kprobes, right? > >>> > >>>>> That is; I don't think CAP_SYS_PERFMON should be allowed to create > >>>>> kprobes. > >>> > >>>>> As might be clear; I don't actually know what the user-ABI is for > >>>>> creating kprobes. > >>> > >>>> There are 2 ABIs nowadays, ftrace and ebpf. perf-probe uses ftrace > >interface to > >>>> define new kprobe events, and those events are treated as > >completely same as > >>>> tracepoint events. On the other hand, ebpf tries to define new > >probe event > >>>> via perf_event interface. Above one is that interface. IOW, it > >creates new kprobe. > >>> > >>> Masami, any plans to make 'perf probe' use the perf_event_open() > >>> interface for creating kprobes/uprobes? > >> > >> Would you mean perf probe to switch to perf_event_open()? > >> No, perf probe is for setting up the ftrace probe events. I think we > >can add an > >> option to use perf_event_open(). But current kprobe creation from > >perf_event_open() > >> is separated from ftrace by design. > > > >I guess we can extend event parser to understand kprobe directly. > >Instead of > > > > perf probe kernel_func > > perf stat/record -e probe:kernel_func ... > > > >We can just do > > > > perf stat/record -e kprobe:kernel_func ... > > > You took the words from my mouth, exactly, that is a perfect use case, an > alternative to the 'perf probe' one of making a disabled event that then gets > activated via record/stat/trace, in many cases it's better, removes the > explicit probe setup case.
Ah, I got it. If the perf event parser just kicks perf's kprobe creation interface, it will be easy. In that case, there should be following differences. - perf * -e "kprobe":kernel_func will put a local (hidden) kprobe events. So ftrace user can not access it. - perf * -e "kprobe":kernel_func may not support inline/function-body nor trace local variables etc. Hm, if we support inline function via -e "kprobe" interface, we have to expand perf_event_open() to support multi-probe event. Thanks, > > Regards, > > - Arnaldo > > > > >Thanks, > >Song > -- Masami Hiramatsu <[email protected]> _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
