On Fri, 10 Jan 2020 21:35:12 -0300 arnaldo.m...@gmail.com wrote: > <keesc...@chromium.org>,Jann Horn <ja...@google.com>,Thomas Gleixner > <t...@linutronix.de>,Tvrtko Ursulin <tvrtko.ursu...@linux.intel.com>,Lionel > Landwerlin <lionel.g.landwer...@intel.com>,linux-kernel > <linux-ker...@vger.kernel.org>,"linux-security-mod...@vger.kernel.org" > <linux-security-mod...@vger.kernel.org>,"seli...@vger.kernel.org" > <seli...@vger.kernel.org>,"intel-...@lists.freedesktop.org" > <intel-...@lists.freedesktop.org>,"b...@vger.kernel.org" > <b...@vger.kernel.org>,"linux-par...@vger.kernel.org" > <linux-par...@vger.kernel.org>,"linuxppc-dev@lists.ozlabs.org" > <linuxppc-dev@lists.ozlabs.org>,"linux-perf-us...@vger.kernel.org" > <linux-perf-us...@vger.kernel.org>,"linux-arm-ker...@lists.infradead.org" > <linux-arm-ker...@lists.infradead.org>,"oprofile-l...@lists.sf.net" > <oprofile-l...@lists.sf.net> > From: Arnaldo Carvalho de Melo <a...@kernel.org> > Message-ID: <a7f0bf73-9189-44ba-9264-c88f2f51c...@kernel.org> > > On January 10, 2020 9:23:27 PM GMT-03:00, Song Liu <songliubrav...@fb.com> > wrote: > > > > > >> On Jan 10, 2020, at 3:47 PM, Masami Hiramatsu <mhira...@kernel.org> > >wrote: > >> > >> On Fri, 10 Jan 2020 13:45:31 -0300 > >> Arnaldo Carvalho de Melo <a...@kernel.org> 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 > ><pet...@infradead.org> 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 <mhira...@kernel.org>
