kernel/bpf/syscall.c | 118 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 118 insertions(+)
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@linux.dev>
---
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@linux.dev
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)
--
2.43.0On Fri, Jun 6, 2025 at 8:03 AM Tao Chen <chen.dylane@linux.dev> wrote:
>
> 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@linux.dev>
> ---
> 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@linux.dev
>
> 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"
I used %#llx to have 0x prepended in front of hex values (here and in
a few other places). That seems to be what we do in other fdinfo
handlers. Applied to bpf-next, thanks.
> + "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
[...]
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