After commit 1b715e1b0ec5 ("bpf: Support ->fill_link_info for perf_event") add
perf_event info, we can also show the info with the method of cat /proc/[fd]/fdinfo.
kprobe fdinfo:
link_type: perf
link_id: 10
prog_tag: bcf7977d3b93787c
prog_id: 20
name: bpf_fentry_test1
offset: 0
missed: 0
addr: ffffffffa28a2904
event_type: kprobe
cookie: 3735928559
uprobe fdinfo:
link_type: perf
link_id: 13
prog_tag: bcf7977d3b93787c
prog_id: 21
name: /proc/self/exe
offset: 63dce4
ref_ctr_offset: 33eee2a
event_type: uprobe
cookie: 3735928559
tracepoint fdinfo:
link_type: perf
link_id: 11
prog_tag: bcf7977d3b93787c
prog_id: 22
tp_name: sched_switch
event_type: tracepoint
cookie: 3735928559
perf_event fdinfo:
link_type: perf
link_id: 12
prog_tag: bcf7977d3b93787c
prog_id: 23
type: 1
config: 2
event_type: event
cookie: 3735928559
Signed-off-by: Tao Chen <chen.dylane@xxxxxxxxx>
---
kernel/bpf/syscall.c | 118 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 118 insertions(+)
Change list:
- v1 -> v2:
- Andrii suggested:
1. define event_type with string
2. print offset and addr with hex
- Jiri suggested:
1. add ref_ctr_offset for uprobe
- v1:
https://lore.kernel.org/bpf/20250604163723.3175258-1-chen.dylane@xxxxxxxxx
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 89d027cd7ca..928ff129087 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3795,6 +3795,31 @@ static int bpf_perf_link_fill_kprobe(const struct perf_event *event,
info->perf_event.kprobe.cookie = event->bpf_cookie;
return 0;
}
+
+static void bpf_perf_link_fdinfo_kprobe(const struct perf_event *event,
+ struct seq_file *seq)
+{
+ const char *name;
+ int err;
+ u32 prog_id, type;
+ u64 offset, addr;
+ unsigned long missed;
+
+ err = bpf_get_perf_event_info(event, &prog_id, &type, &name,
+ &offset, &addr, &missed);
+ if (err)
+ return;
+
+ seq_printf(seq,
+ "name:\t%s\n"
+ "offset:\t%llx\n"
+ "missed:\t%lu\n"
+ "addr:\t%llx\n"
+ "event_type:\t%s\n"
+ "cookie:\t%llu\n",
+ name, offset, missed, addr, type == BPF_FD_TYPE_KRETPROBE ?
+ "kretprobe" : "kprobe", event->bpf_cookie);
+}
#endif
#ifdef CONFIG_UPROBE_EVENTS
@@ -3823,6 +3848,30 @@ static int bpf_perf_link_fill_uprobe(const struct perf_event *event,
info->perf_event.uprobe.ref_ctr_offset = ref_ctr_offset;
return 0;
}
+
+static void bpf_perf_link_fdinfo_uprobe(const struct perf_event *event,
+ struct seq_file *seq)
+{
+ const char *name;
+ int err;
+ u32 prog_id, type;
+ u64 offset, ref_ctr_offset;
+ unsigned long missed;
+
+ err = bpf_get_perf_event_info(event, &prog_id, &type, &name,
+ &offset, &ref_ctr_offset, &missed);
+ if (err)
+ return;
+
+ seq_printf(seq,
+ "name:\t%s\n"
+ "offset:\t%llx\n"
+ "ref_ctr_offset:\t%llx\n"
+ "event_type:\t%s\n"
+ "cookie:\t%llu\n",
+ name, offset, ref_ctr_offset, type == BPF_FD_TYPE_URETPROBE ?
+ "uretprobe" : "uprobe", event->bpf_cookie);
+}
#endif
static int bpf_perf_link_fill_probe(const struct perf_event *event,
@@ -3891,10 +3940,79 @@ static int bpf_perf_link_fill_link_info(const struct bpf_link *link,
}
}
+static void bpf_perf_event_link_show_fdinfo(const struct perf_event *event,
+ struct seq_file *seq)
+{
+ seq_printf(seq,
+ "type:\t%u\n"
+ "config:\t%llu\n"
+ "event_type:\t%s\n"
+ "cookie:\t%llu\n",
+ event->attr.type, event->attr.config,
+ "event", event->bpf_cookie);
+}
+
+static void bpf_tracepoint_link_show_fdinfo(const struct perf_event *event,
+ struct seq_file *seq)
+{
+ int err;
+ const char *name;
+ u32 prog_id;
+
+ err = bpf_get_perf_event_info(event, &prog_id, NULL, &name, NULL,
+ NULL, NULL);
+ if (err)
+ return;
+
+ seq_printf(seq,
+ "tp_name:\t%s\n"
+ "event_type:\t%s\n"
+ "cookie:\t%llu\n",
+ name, "tracepoint", event->bpf_cookie);
+}
+
+static void bpf_probe_link_show_fdinfo(const struct perf_event *event,
+ struct seq_file *seq)
+{
+#ifdef CONFIG_KPROBE_EVENTS
+ if (event->tp_event->flags & TRACE_EVENT_FL_KPROBE)
+ return bpf_perf_link_fdinfo_kprobe(event, seq);
+#endif
+
+#ifdef CONFIG_UPROBE_EVENTS
+ if (event->tp_event->flags & TRACE_EVENT_FL_UPROBE)
+ return bpf_perf_link_fdinfo_uprobe(event, seq);
+#endif
+}
+
+static void bpf_perf_link_show_fdinfo(const struct bpf_link *link,
+ struct seq_file *seq)
+{
+ struct bpf_perf_link *perf_link;
+ const struct perf_event *event;
+
+ perf_link = container_of(link, struct bpf_perf_link, link);
+ event = perf_get_event(perf_link->perf_file);
+ if (IS_ERR(event))
+ return;
+
+ switch (event->prog->type) {
+ case BPF_PROG_TYPE_PERF_EVENT:
+ return bpf_perf_event_link_show_fdinfo(event, seq);
+ case BPF_PROG_TYPE_TRACEPOINT:
+ return bpf_tracepoint_link_show_fdinfo(event, seq);
+ case BPF_PROG_TYPE_KPROBE:
+ return bpf_probe_link_show_fdinfo(event, seq);
+ default:
+ return;
+ }
+}
+
static const struct bpf_link_ops bpf_perf_link_lops = {
.release = bpf_perf_link_release,
.dealloc = bpf_perf_link_dealloc,
.fill_link_info = bpf_perf_link_fill_link_info,
+ .show_fdinfo = bpf_perf_link_show_fdinfo,
};
static int bpf_perf_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
--
2.43.0
