Subject: Re: [PATCH v5 0/6] enable creating [k,u]probe with perf_event_open
To: Song Liu <songliubraving@fb.com>, peterz@infradead.org,
        rostedt@goodmis.org, mingo@redhat.com, davem@davemloft.net,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: kernel-team@fb.com
References: <20171206224518.3598254-1-songliubraving@fb.com>
From: Daniel Borkmann <daniel@iogearbox.net>
Message-ID: <530f908c-9c34-2db9-1d98-db1c790fa81b@iogearbox.net>
Date: Fri, 8 Dec 2017 20:57:43 +0100
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On 12/06/2017 11:45 PM, Song Liu wrote:
> Changes PATCH v4 to PATCH v5:
>   Remove PERF_PROBE_CONFIG_IS_RETPROBE from uapi, use PMU_FORMAT_ATTR
>   instead.
> 
> Changes PATCH v3 to PATCH v4:
>   Remove uapi define MAX_PROBE_FUNC_NAME_LEN, use KSYM_NAME_LEN instead.
>   Add flag PERF_PROBE_CONFIG_IS_RETPROBE for config field of [k,u]probe.
>   Optimize ifdef's of CONFIG_KPROBE_EVENTS and CONFIG_UPROBE_EVENTS.
>   Optimize checks in perf_event_is_tracing().
>   Optimize perf_tp_register().
> 
> Changes PATCH v2 to PATCH v3:
>   Remove fixed type PERF_TYPE_KPROBE and PERF_TYPE_UPROBE, use dynamic
>   type instead.
>   Update userspace (samples/bpf, bcc) to look up type from sysfs.
>   Change License info in test_many_kprobe_user.c as Philippe Ombredanne
>   suggested.
> 
> Changes PATCH v1 to PATCH v2:
>   Split PERF_TYPE_PROBE into PERF_TYPE_KPROBE and PERF_TYPE_UPROBE.
>   Split perf_probe into perf_kprobe and perf_uprobe.
>   Remove struct probe_desc, use config1 and config2 instead.
> 
> Changes RFC v2 to PATCH v1:
>   Check type PERF_TYPE_PROBE in perf_event_set_filter().
>   Rebase on to tip perf/core.
> 
> Changes RFC v1 to RFC v2:
>   Fix build issue reported by kbuild test bot by adding ifdef of
>   CONFIG_KPROBE_EVENTS, and CONFIG_UPROBE_EVENTS.
> 
> RFC v1 cover letter:
> 
> This is to follow up the discussion over "new kprobe api" at Linux
> Plumbers 2017:
> 
> https://www.linuxplumbersconf.org/2017/ocw/proposals/4808
> 
> With current kernel, user space tools can only create/destroy [k,u]probes
> with a text-based API (kprobe_events and uprobe_events in tracefs). This
> approach relies on user space to clean up the [k,u]probe after using them.
> However, this is not easy for user space to clean up properly.
> 
> To solve this problem, we introduce a file descriptor based API.
> Specifically, we extended perf_event_open to create [k,u]probe, and attach
> this [k,u]probe to the file descriptor created by perf_event_open. These
> [k,u]probe are associated with this file descriptor, so they are not
> available in tracefs.
> 
> We reuse large portion of existing trace_kprobe and trace_uprobe code.
> Currently, the file descriptor API does not support arguments as the
> text-based API does. This should not be a problem, as user of the file
> decriptor based API read data through other methods (bpf, etc.).
> 
> I also include a patch to to bcc, and a patch to man-page perf_even_open.
> Please see the list below. A fork of bcc with this patch is also available
> on github:
> 
>   https://github.com/liu-song-6/bcc/tree/perf_event_open

Peter / Stephen, I presume this will be routed through one of you, if
not please yell.

Thanks,
Daniel

> man-pages patch:
>   perf_event_open.2: add type kprobe and uprobe
> 
> bcc patch:
>   bcc: Try use new API to create [k,u]probe with perf_event_open
> 
> kernel patches:
> 
> Song Liu (6):
>   perf: prepare perf_event.h for new types perf_kprobe and perf_uprobe
>   perf: copy new perf_event.h to tools/include/uapi
>   perf: implement pmu perf_kprobe
>   perf: implement pmu perf_uprobe
>   bpf: add option for bpf_load.c to use perf_kprobe
>   bpf: add new test test_many_kprobe
> 
>  include/linux/trace_events.h          |   8 ++
>  include/uapi/linux/perf_event.h       |   4 +
>  kernel/events/core.c                  | 131 +++++++++++++++++++++++-
>  kernel/trace/trace_event_perf.c       | 102 +++++++++++++++++++
>  kernel/trace/trace_kprobe.c           |  91 +++++++++++++++--
>  kernel/trace/trace_probe.h            |  11 ++
>  kernel/trace/trace_uprobe.c           |  86 ++++++++++++++--
>  samples/bpf/Makefile                  |   3 +
>  samples/bpf/bpf_load.c                |  66 ++++++++++--
>  samples/bpf/bpf_load.h                |  14 +++
>  samples/bpf/test_many_kprobe_user.c   | 186 ++++++++++++++++++++++++++++++++++
>  tools/include/uapi/linux/perf_event.h |   4 +
>  12 files changed, 677 insertions(+), 29 deletions(-)
>  create mode 100644 samples/bpf/test_many_kprobe_user.c
> 
> --
> 2.9.5
>