From: Yafang Shao <laoar.shao@gmail.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
martin.lau@linux.dev, song@kernel.org, yhs@fb.com,
john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com,
haoluo@google.com, jolsa@kernel.org, quentin@isovalent.com,
bpf@vger.kernel.org
Subject: Re: [PATCH v2 bpf-next 08/11] bpf: Support ->fill_link_info for perf_event
Date: Sat, 10 Jun 2023 10:21:06 +0800 [thread overview]
Message-ID: <CALOAHbBb5p92oBe5HKPu_5ADXkNErAKz2hu-wMxjLje80kymKA@mail.gmail.com> (raw)
In-Reply-To: <CAEf4BzYJWQA4z4PVbWk_jzPKbf76wJJrcoOD-zN0___qKK4-BQ@mail.gmail.com>
On Sat, Jun 10, 2023 at 2:26 AM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Fri, Jun 9, 2023 at 2:57 AM Yafang Shao <laoar.shao@gmail.com> wrote:
> >
> > On Fri, Jun 9, 2023 at 5:53 PM Yafang Shao <laoar.shao@gmail.com> wrote:
> > >
> > > On Fri, Jun 9, 2023 at 7:12 AM Andrii Nakryiko
> > > <andrii.nakryiko@gmail.com> wrote:
> > > >
> > > > On Thu, Jun 8, 2023 at 3:35 AM Yafang Shao <laoar.shao@gmail.com> wrote:
> > > > >
> > > > > By introducing support for ->fill_link_info to the perf_event link, users
> > > > > gain the ability to inspect it using `bpftool link show`. While the current
> > > > > approach involves accessing this information via `bpftool perf show`,
> > > > > consolidating link information for all link types in one place offers
> > > > > greater convenience. Additionally, this patch extends support to the
> > > > > generic perf event, which is not currently accommodated by
> > > > > `bpftool perf show`. While only the perf type and config are exposed to
> > > > > userspace, other attributes such as sample_period and sample_freq are
> > > > > ignored. It's important to note that if kptr_restrict is set to 2, the
> > > > > probed address will not be exposed, maintaining security measures.
> > > > >
> > > > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> > > > > ---
> > > > > include/uapi/linux/bpf.h | 22 ++++++++++
> > > > > kernel/bpf/syscall.c | 98 ++++++++++++++++++++++++++++++++++++++++++
> > > > > tools/include/uapi/linux/bpf.h | 22 ++++++++++
> > > > > 3 files changed, 142 insertions(+)
> > > > >
> > > > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > > > > index d99cc16..c3b821d 100644
> > > > > --- a/include/uapi/linux/bpf.h
> > > > > +++ b/include/uapi/linux/bpf.h
> > > > > @@ -6443,6 +6443,28 @@ struct bpf_link_info {
> > > > > __u32 count;
> > > > > __u8 retprobe;
> > > > > } kprobe_multi;
> > > > > + union {
> > > > > + struct {
> > > > > + /* The name is:
> > > > > + * a) uprobe: file name
> > > > > + * b) kprobe: kernel function
> > > > > + */
> > > > > + __aligned_u64 name; /* in/out: name buffer ptr */
> > > > > + __u32 name_len;
> > > > > + __u32 offset; /* offset from the name */
> > > > > + __u64 addr;
> > > > > + __u8 retprobe;
> > > > > + } probe; /* uprobe, kprobe */
> > > > > + struct {
> > > > > + /* in/out: tracepoint name buffer ptr */
> > > > > + __aligned_u64 tp_name;
> > > > > + __u32 name_len;
> > > > > + } tp; /* tracepoint */
> > > > > + struct {
> > > > > + __u64 config;
> > > > > + __u32 type;
> > > > > + } event; /* generic perf event */
> > > >
> > > > how should the user know which of those structs are relevant? we need
> > > > some enum to specify what kind of perf_event link it is?
> > > >
> > >
> > > Do you mean that we add a new field 'type' into the union perf_event,
> > > as follows ?
> > > union {
> > > __u32 type;
> > > struct {} probe; /* BPF_LINK_TYPE_PERF_EVENT_PROBE */
> > > struct {} tp; /* BPF_LINK_TYPE_PERF_EVENT_TP */
> > > struct {} event; /* BPF_LINK_TYPE_PERF_EVENT_EVENT */
> > > };
> > >
> >
> > Correct it:
> >
> > struct {
> > __u32 type;
> > union {
> > struct {} probe; /* BPF_LINK_TYPE_PERF_EVENT_PROBE */
> > struct {} tp; /* BPF_LINK_TYPE_PERF_EVENT_TP */
> > struct {} event; /* BPF_LINK_TYPE_PERF_EVENT_EVENT */
> > };
> > } perf_event;
>
> yes, something like this. Unless we want to leave perf_event {} to
> mean really perf event only, while kprobe/uprobe/tracepoint should be
> their own separate sections at the same level of nestedness as
> perf_Event and other cases. Not sure.
>
Thanks for your explanation. I will think about it.
--
Regards
Yafang
next prev parent reply other threads:[~2023-06-10 2:21 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-08 10:35 [PATCH v2 bpf-next 00/11] bpf: Support ->fill_link_info for kprobe_multi and perf_event links Yafang Shao
2023-06-08 10:35 ` [PATCH v2 bpf-next 01/11] bpf: Support ->fill_link_info for kprobe_multi Yafang Shao
2023-06-08 23:05 ` Andrii Nakryiko
2023-06-09 9:13 ` Yafang Shao
2023-06-09 18:25 ` Andrii Nakryiko
2023-06-10 2:19 ` Yafang Shao
2023-06-08 10:35 ` [PATCH v2 bpf-next 02/11] bpftool: Add address filtering in kernel_syms_load() Yafang Shao
2023-06-08 10:35 ` [PATCH v2 bpf-next 03/11] bpftool: Show probed function in kprobe_multi link info Yafang Shao
2023-06-08 23:08 ` Andrii Nakryiko
2023-06-09 9:15 ` Yafang Shao
2023-06-08 10:35 ` [PATCH v2 bpf-next 04/11] bpf: Protect probed address based on kptr_restrict setting Yafang Shao
2023-06-08 23:08 ` Andrii Nakryiko
2023-06-09 9:16 ` Yafang Shao
2023-06-08 10:35 ` [PATCH v2 bpf-next 05/11] bpf: Clear the probe_addr for uprobe Yafang Shao
2023-06-08 10:35 ` [PATCH v2 bpf-next 06/11] bpf: Expose symbol addresses for precise identification Yafang Shao
2023-06-08 10:35 ` [PATCH v2 bpf-next 07/11] bpf: Add a common helper bpf_copy_to_user() Yafang Shao
2023-06-08 10:35 ` [PATCH v2 bpf-next 08/11] bpf: Support ->fill_link_info for perf_event Yafang Shao
2023-06-08 23:12 ` Andrii Nakryiko
2023-06-09 9:53 ` Yafang Shao
2023-06-09 9:56 ` Yafang Shao
2023-06-09 18:26 ` Andrii Nakryiko
2023-06-10 2:21 ` Yafang Shao [this message]
2023-06-08 10:35 ` [PATCH v2 bpf-next 09/11] libbpf: Add perf event names Yafang Shao
2023-06-08 23:14 ` Andrii Nakryiko
2023-06-09 4:36 ` Song Liu
2023-06-10 2:22 ` Yafang Shao
2023-06-10 20:34 ` Quentin Monnet
2023-06-11 15:52 ` Yafang Shao
2023-06-10 22:37 ` Jiri Olsa
2023-06-10 22:43 ` Jiri Olsa
2023-06-11 15:55 ` Yafang Shao
2023-06-08 10:35 ` [PATCH v2 bpf-next 10/11] bpftool: Move get_prog_info() into do_show_link() Yafang Shao
2023-06-08 10:35 ` [PATCH v2 bpf-next 11/11] bpftool: Show probed function in perf_event link info Yafang Shao
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