[PATCH bpf-next v3 1/2] bpf: Add show_fdinfo for uprobe_multi

[PATCH bpf-next v3 1/2] bpf: Add show_fdinfo for uprobe_multi

[Tao Chen]

Show uprobe_multi link info with fdinfo, the info as follows:

link_type:	uprobe_multi
link_id:	9
prog_tag:	e729f789e34a8eca
prog_id:	39
type:	uprobe_multi
uprobe_cnt:	3
pid:	0
path:	/home/dylane/bpf/tools/testing/selftests/bpf/test_progs
offset           ref_ctr_offset   cookie
0xa69f13         0x0              3
0xa69f1e         0x0              1
0xa69f29         0x0              2

Signed-off-by: Tao Chen <chen.dylane@linux.dev>
---
 kernel/trace/bpf_trace.c | 47 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

Change list:
  v2 -> v3:
    - show info in one line for multi events.(Jiri)
  v2:
  https://lore.kernel.org/bpf/20250615150514.418581-1-chen.dylane@linux.dev 

  v1 -> v2:
    - replace 'func_cnt' with 'uprobe_cnt'.(Andrii)
    - print func name is more readable and security for kprobe_multi.(Alexei)
  v1:
  https://lore.kernel.org/bpf/20250612115556.295103-1-chen.dylane@linux.dev

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 24b94870b50..2d422f897ac 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3157,10 +3157,57 @@ static int bpf_uprobe_multi_link_fill_link_info(const struct bpf_link *link,
 	return err;
 }
 
+#ifdef CONFIG_PROC_FS
+static void bpf_uprobe_multi_show_fdinfo(const struct bpf_link *link,
+					 struct seq_file *seq)
+{
+	struct bpf_uprobe_multi_link *umulti_link;
+	char *p, *buf;
+
+	umulti_link = container_of(link, struct bpf_uprobe_multi_link, link);
+
+	buf = kmalloc(PATH_MAX, GFP_KERNEL);
+	if (!buf)
+		return;
+
+	p = d_path(&umulti_link->path, buf, PATH_MAX);
+	if (IS_ERR(p)) {
+		kfree(buf);
+		return;
+	}
+
+	seq_printf(seq,
+		   "type:\t%s\n"
+		   "uprobe_cnt:\t%u\n"
+		   "pid:\t%u\n"
+		   "path:\t%s\n",
+		   umulti_link->flags == BPF_F_UPROBE_MULTI_RETURN ?
+					 "uretprobe_multi" : "uprobe_multi",
+		   umulti_link->cnt,
+		   umulti_link->task ? task_pid_nr_ns(umulti_link->task,
+			   task_active_pid_ns(current)) : 0,
+		   p);
+
+	seq_printf(seq, "%-16s %-16s %-16s\n", "offset", "ref_ctr_offset", "cookie");
+	for (int i = 0; i < umulti_link->cnt; i++) {
+		seq_printf(seq,
+			   "%#-16llx %#-16lx %-16llu\n",
+			   umulti_link->uprobes[i].offset,
+			   umulti_link->uprobes[i].ref_ctr_offset,
+			   umulti_link->uprobes[i].cookie);
+	}
+
+	kfree(buf);
+}
+#endif
+
 static const struct bpf_link_ops bpf_uprobe_multi_link_lops = {
 	.release = bpf_uprobe_multi_link_release,
 	.dealloc_deferred = bpf_uprobe_multi_link_dealloc,
 	.fill_link_info = bpf_uprobe_multi_link_fill_link_info,
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo = bpf_uprobe_multi_show_fdinfo,
+#endif
 };
 
 static int uprobe_prog_run(struct bpf_uprobe *uprobe,
-- 
2.48.1

[PATCH bpf-next v3 2/2] bpf: Add show_fdinfo for kprobe_multi

[Tao Chen]

Show kprobe_multi link info with fdinfo, the info as follows:

link_type:	kprobe_multi
link_id:	1
prog_tag:	a15b7646cb7f3322
prog_id:	21
type:	kprobe_multi
kprobe_cnt:	8
missed:	0
cookie           func
1                bpf_fentry_test1
7                bpf_fentry_test2
2                bpf_fentry_test3
3                bpf_fentry_test4
4                bpf_fentry_test5
5                bpf_fentry_test6
6                bpf_fentry_test7
8                bpf_fentry_test8

Signed-off-by: Tao Chen <chen.dylane@linux.dev>
---
 kernel/trace/bpf_trace.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 2d422f897ac..fcf19e233b5 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2623,10 +2623,42 @@ static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
 	return err;
 }
 
+#ifdef CONFIG_PROC_FS
+static void bpf_kprobe_multi_show_fdinfo(const struct bpf_link *link,
+					 struct seq_file *seq)
+{
+	struct bpf_kprobe_multi_link *kmulti_link;
+	char sym[KSYM_NAME_LEN];
+
+	kmulti_link = container_of(link, struct bpf_kprobe_multi_link, link);
+
+	seq_printf(seq,
+		   "type:\t%s\n"
+		   "kprobe_cnt:\t%u\n"
+		   "missed:\t%lu\n",
+		   kmulti_link->flags == BPF_F_KPROBE_MULTI_RETURN ? "kretprobe_multi" :
+					 "kprobe_multi",
+		   kmulti_link->cnt,
+		   kmulti_link->fp.nmissed);
+
+	seq_printf(seq, "%-16s %-16s\n", "cookie", "func");
+	for (int i = 0; i < kmulti_link->cnt; i++) {
+		sprint_symbol_no_offset(sym, kmulti_link->addrs[i]);
+		seq_printf(seq,
+			   "%-16llu %-16s\n",
+			   kmulti_link->cookies[i],
+			   sym);
+	}
+}
+#endif
+
 static const struct bpf_link_ops bpf_kprobe_multi_link_lops = {
 	.release = bpf_kprobe_multi_link_release,
 	.dealloc_deferred = bpf_kprobe_multi_link_dealloc,
 	.fill_link_info = bpf_kprobe_multi_link_fill_link_info,
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo = bpf_kprobe_multi_show_fdinfo,
+#endif
 };
 
 static void bpf_kprobe_multi_cookie_swap(void *a, void *b, int size, const void *priv)
-- 
2.48.1

Re: [PATCH bpf-next v3 2/2] bpf: Add show_fdinfo for kprobe_multi

[Alexei Starovoitov]

On Mon, Jun 16, 2025 at 6:03 AM Tao Chen <chen.dylane@linux.dev> wrote:
>
> Show kprobe_multi link info with fdinfo, the info as follows:
>
> link_type:      kprobe_multi
> link_id:        1
> prog_tag:       a15b7646cb7f3322
> prog_id:        21
> type:   kprobe_multi
> kprobe_cnt:     8
> missed: 0
> cookie           func
> 1                bpf_fentry_test1
> 7                bpf_fentry_test2
> 2                bpf_fentry_test3
> 3                bpf_fentry_test4
> 4                bpf_fentry_test5
> 5                bpf_fentry_test6
> 6                bpf_fentry_test7
> 8                bpf_fentry_test8
>
> Signed-off-by: Tao Chen <chen.dylane@linux.dev>
> ---
>  kernel/trace/bpf_trace.c | 32 ++++++++++++++++++++++++++++++++
>  1 file changed, 32 insertions(+)
>
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 2d422f897ac..fcf19e233b5 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -2623,10 +2623,42 @@ static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
>         return err;
>  }
>
> +#ifdef CONFIG_PROC_FS
> +static void bpf_kprobe_multi_show_fdinfo(const struct bpf_link *link,
> +                                        struct seq_file *seq)
> +{
> +       struct bpf_kprobe_multi_link *kmulti_link;
> +       char sym[KSYM_NAME_LEN];
> +
> +       kmulti_link = container_of(link, struct bpf_kprobe_multi_link, link);
> +
> +       seq_printf(seq,
> +                  "type:\t%s\n"
> +                  "kprobe_cnt:\t%u\n"
> +                  "missed:\t%lu\n",
> +                  kmulti_link->flags == BPF_F_KPROBE_MULTI_RETURN ? "kretprobe_multi" :
> +                                        "kprobe_multi",
> +                  kmulti_link->cnt,
> +                  kmulti_link->fp.nmissed);
> +
> +       seq_printf(seq, "%-16s %-16s\n", "cookie", "func");
> +       for (int i = 0; i < kmulti_link->cnt; i++) {
> +               sprint_symbol_no_offset(sym, kmulti_link->addrs[i]);
> +               seq_printf(seq,
> +                          "%-16llu %-16s\n",
> +                          kmulti_link->cookies[i],
> +                          sym);

Why call sprint_symbol_no_offset() directly ?
%pB is fine.
+off doesn't disclose anything.

pw-bot: cr

Re: [PATCH bpf-next v3 2/2] bpf: Add show_fdinfo for kprobe_multi

[Tao Chen]

在 2025/6/19 09:46, Alexei Starovoitov 写道:
> On Mon, Jun 16, 2025 at 6:03 AM Tao Chen <chen.dylane@linux.dev> wrote:
>>
>> Show kprobe_multi link info with fdinfo, the info as follows:
>>
>> link_type:      kprobe_multi
>> link_id:        1
>> prog_tag:       a15b7646cb7f3322
>> prog_id:        21
>> type:   kprobe_multi
>> kprobe_cnt:     8
>> missed: 0
>> cookie           func
>> 1                bpf_fentry_test1
>> 7                bpf_fentry_test2
>> 2                bpf_fentry_test3
>> 3                bpf_fentry_test4
>> 4                bpf_fentry_test5
>> 5                bpf_fentry_test6
>> 6                bpf_fentry_test7
>> 8                bpf_fentry_test8
>>
>> Signed-off-by: Tao Chen <chen.dylane@linux.dev>
>> ---
>>   kernel/trace/bpf_trace.c | 32 ++++++++++++++++++++++++++++++++
>>   1 file changed, 32 insertions(+)
>>
>> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
>> index 2d422f897ac..fcf19e233b5 100644
>> --- a/kernel/trace/bpf_trace.c
>> +++ b/kernel/trace/bpf_trace.c
>> @@ -2623,10 +2623,42 @@ static int bpf_kprobe_multi_link_fill_link_info(const struct bpf_link *link,
>>          return err;
>>   }
>>
>> +#ifdef CONFIG_PROC_FS
>> +static void bpf_kprobe_multi_show_fdinfo(const struct bpf_link *link,
>> +                                        struct seq_file *seq)
>> +{
>> +       struct bpf_kprobe_multi_link *kmulti_link;
>> +       char sym[KSYM_NAME_LEN];
>> +
>> +       kmulti_link = container_of(link, struct bpf_kprobe_multi_link, link);
>> +
>> +       seq_printf(seq,
>> +                  "type:\t%s\n"
>> +                  "kprobe_cnt:\t%u\n"
>> +                  "missed:\t%lu\n",
>> +                  kmulti_link->flags == BPF_F_KPROBE_MULTI_RETURN ? "kretprobe_multi" :
>> +                                        "kprobe_multi",
>> +                  kmulti_link->cnt,
>> +                  kmulti_link->fp.nmissed);
>> +
>> +       seq_printf(seq, "%-16s %-16s\n", "cookie", "func");
>> +       for (int i = 0; i < kmulti_link->cnt; i++) {
>> +               sprint_symbol_no_offset(sym, kmulti_link->addrs[i]);
>> +               seq_printf(seq,
>> +                          "%-16llu %-16s\n",
>> +                          kmulti_link->cookies[i],
>> +                          sym);
> 
> Why call sprint_symbol_no_offset() directly ?
> %pB is fine.
> +off doesn't disclose anything.
> 
> pw-bot: cr

My problem, sorry for that, i had some issues with using printk to show 
func name directly before. Actually, i used it incorrectly. How about 
%pS, it looks more accurate. Thanks!

%pB format
cookie           func
8                __pfx_bpf_fentry_test1+0x10/0x10
2                __pfx_bpf_fentry_test2+0x10/0x10
7                __pfx_bpf_fentry_test3+0x10/0x10

%pS format
cookie           func
8                bpf_fentry_test1+0x0/0x20
2                bpf_fentry_test2+0x0/0x20
7                bpf_fentry_test3+0x0/0x20

-- 
Best Regards
Tao Chen