On Fri, Jun 9, 2023 at 7:12 AM Andrii Nakryiko
<andrii.nakryiko@xxxxxxxxx> wrote:
>
> On Thu, Jun 8, 2023 at 3:35 AM Yafang Shao <laoar.shao@xxxxxxxxx> 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@xxxxxxxxx>
> > ---
> > 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 */
};
--
Regards
Yafang
