[PATCH v4 2/9] perf/core: open access for CAP_SYS_PERFMON privileged process

[Song Liu]

> On Jan 10, 2020, at 3:47 PM, Masami Hiramatsu <mhiramat at kernel.org> wrote:
> 
> On Fri, 10 Jan 2020 13:45:31 -0300
> Arnaldo Carvalho de Melo <acme at 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 <peterz at 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 ...

Thanks,
Song