[PATCH bpf-next v2 1/2] bpf: Add show_fdinfo for uprobe_multi

[PATCH bpf-next v2 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:	58
type:	uprobe_multi
uprobe_cnt:	3
pid:	0
path:	/home/dylane/bpf/tools/testing/selftests/bpf/test_progs
offset:	0xa69ed7
ref_ctr_offset:	0x0
cookie:	3
offset:	0xa69ee2
ref_ctr_offset:	0x0
cookie:	1
offset:	0xa69eed
ref_ctr_offset:	0x0
cookie:	2

Signed-off-by: Tao Chen <chen.dylane@linux.dev>
---
 kernel/trace/bpf_trace.c | 48 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

Change list:
  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..9a8ca8a8e2b 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -3157,10 +3157,58 @@ 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);
+
+	for (int i = 0; i < umulti_link->cnt; i++) {
+		seq_printf(seq,
+			   "offset:\t%#llx\n"
+			   "ref_ctr_offset:\t%#lx\n"
+			   "cookie:\t%llu\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 v2 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:	3
prog_tag:	e8225cbcc9cdffef
prog_id:	29
type:	kprobe_multi
kprobe_cnt:	8
missed:	0
func:	bpf_fentry_test1+0x0/0x20
cookie:	1
func:	bpf_fentry_test2+0x0/0x20
cookie:	7
func:	bpf_fentry_test3+0x0/0x20
cookie:	2
func:	bpf_fentry_test4+0x0/0x20
cookie:	3
func:	bpf_fentry_test5+0x0/0x20
cookie:	4
func:	bpf_fentry_test6+0x0/0x20
cookie:	5
func:	bpf_fentry_test7+0x0/0x20
cookie:	6
func:	bpf_fentry_test8+0x0/0x10
cookie:	8

Signed-off-by: Tao Chen <chen.dylane@linux.dev>
---
 kernel/trace/bpf_trace.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 9a8ca8a8e2b..d060c61e4e4 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2623,10 +2623,43 @@ 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);
+
+	for (int i = 0; i < kmulti_link->cnt; i++) {
+		sprint_symbol(sym, kmulti_link->addrs[i]);
+		seq_printf(seq,
+			  "func:\t%s\n"
+			  "cookie:\t%llu\n",
+			  sym,
+			  kmulti_link->cookies[i]
+			  );
+	}
+}
+#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 v2 2/2] bpf: Add show_fdinfo for kprobe_multi

[Jiri Olsa]

On Sun, Jun 15, 2025 at 11:05:14PM +0800, Tao Chen wrote:
> Show kprobe_multi link info with fdinfo, the info as follows:
> 
> link_type:	kprobe_multi
> link_id:	3
> prog_tag:	e8225cbcc9cdffef
> prog_id:	29
> type:	kprobe_multi
> kprobe_cnt:	8
> missed:	0
> func:	bpf_fentry_test1+0x0/0x20
> cookie:	1
> func:	bpf_fentry_test2+0x0/0x20
> cookie:	7
> func:	bpf_fentry_test3+0x0/0x20
> cookie:	2
> func:	bpf_fentry_test4+0x0/0x20
> cookie:	3
> func:	bpf_fentry_test5+0x0/0x20
> cookie:	4
> func:	bpf_fentry_test6+0x0/0x20
> cookie:	5
> func:	bpf_fentry_test7+0x0/0x20
> cookie:	6
> func:	bpf_fentry_test8+0x0/0x10
> cookie:	8
> 
> Signed-off-by: Tao Chen <chen.dylane@linux.dev>
> ---
>  kernel/trace/bpf_trace.c | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 9a8ca8a8e2b..d060c61e4e4 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -2623,10 +2623,43 @@ 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);
> +
> +	for (int i = 0; i < kmulti_link->cnt; i++) {
> +		sprint_symbol(sym, kmulti_link->addrs[i]);

I think you could use specifier to do the translation for you,
check Documentation/core-api/printk-formats.rst:

        %pS     versatile_init+0x0/0x110 [module_name]



> +		seq_printf(seq,
> +			  "func:\t%s\n"
> +			  "cookie:\t%llu\n",
> +			  sym,
> +			  kmulti_link->cookies[i]
> +			  );

bracket should be on the previous line

jirka


> +	}
> +}
> +#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 v2 2/2] bpf: Add show_fdinfo for kprobe_multi

[Tao Chen]

在 2025/6/16 15:40, Jiri Olsa 写道:
> On Sun, Jun 15, 2025 at 11:05:14PM +0800, Tao Chen wrote:
>> Show kprobe_multi link info with fdinfo, the info as follows:
>>
>> link_type:	kprobe_multi
>> link_id:	3
>> prog_tag:	e8225cbcc9cdffef
>> prog_id:	29
>> type:	kprobe_multi
>> kprobe_cnt:	8
>> missed:	0
>> func:	bpf_fentry_test1+0x0/0x20
>> cookie:	1
>> func:	bpf_fentry_test2+0x0/0x20
>> cookie:	7
>> func:	bpf_fentry_test3+0x0/0x20
>> cookie:	2
>> func:	bpf_fentry_test4+0x0/0x20
>> cookie:	3
>> func:	bpf_fentry_test5+0x0/0x20
>> cookie:	4
>> func:	bpf_fentry_test6+0x0/0x20
>> cookie:	5
>> func:	bpf_fentry_test7+0x0/0x20
>> cookie:	6
>> func:	bpf_fentry_test8+0x0/0x10
>> cookie:	8
>>
>> Signed-off-by: Tao Chen <chen.dylane@linux.dev>
>> ---
>>   kernel/trace/bpf_trace.c | 33 +++++++++++++++++++++++++++++++++
>>   1 file changed, 33 insertions(+)
>>
>> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
>> index 9a8ca8a8e2b..d060c61e4e4 100644
>> --- a/kernel/trace/bpf_trace.c
>> +++ b/kernel/trace/bpf_trace.c
>> @@ -2623,10 +2623,43 @@ 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);
>> +
>> +	for (int i = 0; i < kmulti_link->cnt; i++) {
>> +		sprint_symbol(sym, kmulti_link->addrs[i]);
> 
> I think you could use specifier to do the translation for you,
> check Documentation/core-api/printk-formats.rst:
> 
>          %pS     versatile_init+0x0/0x110 [module_name]
> 

I'll refer to that, thanks!

> 
> 
>> +		seq_printf(seq,
>> +			  "func:\t%s\n"
>> +			  "cookie:\t%llu\n",
>> +			  sym,
>> +			  kmulti_link->cookies[i]
>> +			  );
> 
> bracket should be on the previous line
> 

will fix it in v3, thanks.

> jirka
> 
> 
>> +	}
>> +}
>> +#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
>>


-- 
Best Regards
Tao Chen

Re: [PATCH bpf-next v2 1/2] bpf: Add show_fdinfo for uprobe_multi

[Jiri Olsa]

On Sun, Jun 15, 2025 at 11:05:13PM +0800, Tao Chen wrote:
> Show uprobe_multi link info with fdinfo, the info as follows:
> 
> link_type:	uprobe_multi
> link_id:	9
> prog_tag:	e729f789e34a8eca
> prog_id:	58
> type:	uprobe_multi
> uprobe_cnt:	3
> pid:	0
> path:	/home/dylane/bpf/tools/testing/selftests/bpf/test_progs
> offset:	0xa69ed7
> ref_ctr_offset:	0x0
> cookie:	3
> offset:	0xa69ee2
> ref_ctr_offset:	0x0
> cookie:	1
> offset:	0xa69eed
> ref_ctr_offset:	0x0
> cookie:	2

hi,
does this need to be 'tag: value' format ? bpftool uses:

        offset             ref_ctr_offset     cookies
        0xe558             0x0                0x0
        0x2574e            0x0                0x0
        0x6c393            0x0                0x0

which might be more readable, or at least extra line after each uprobe?
also using spaces instead of tabs  to align the values might help

same for kprobe_multi, otherwise looks lgtm

thanks,
jirka


> 
> Signed-off-by: Tao Chen <chen.dylane@linux.dev>
> ---
>  kernel/trace/bpf_trace.c | 48 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 48 insertions(+)
> 
> Change list:
>   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..9a8ca8a8e2b 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -3157,10 +3157,58 @@ 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);
> +
> +	for (int i = 0; i < umulti_link->cnt; i++) {
> +		seq_printf(seq,
> +			   "offset:\t%#llx\n"
> +			   "ref_ctr_offset:\t%#lx\n"
> +			   "cookie:\t%llu\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
> 

Re: [PATCH bpf-next v2 1/2] bpf: Add show_fdinfo for uprobe_multi

[Tao Chen]

在 2025/6/16 15:40, Jiri Olsa 写道:
> On Sun, Jun 15, 2025 at 11:05:13PM +0800, Tao Chen wrote:
>> Show uprobe_multi link info with fdinfo, the info as follows:
>>
>> link_type:	uprobe_multi
>> link_id:	9
>> prog_tag:	e729f789e34a8eca
>> prog_id:	58
>> type:	uprobe_multi
>> uprobe_cnt:	3
>> pid:	0
>> path:	/home/dylane/bpf/tools/testing/selftests/bpf/test_progs
>> offset:	0xa69ed7
>> ref_ctr_offset:	0x0
>> cookie:	3
>> offset:	0xa69ee2
>> ref_ctr_offset:	0x0
>> cookie:	1
>> offset:	0xa69eed
>> ref_ctr_offset:	0x0
>> cookie:	2
> 
> hi,
> does this need to be 'tag: value' format ? bpftool uses:
> 
>          offset             ref_ctr_offset     cookies
>          0xe558             0x0                0x0
>          0x2574e            0x0                0x0
>          0x6c393            0x0                0x0
> 
> which might be more readable, or at least extra line after each uprobe?
> also using spaces instead of tabs  to align the values might help
> 
> same for kprobe_multi, otherwise looks lgtm
> 

That's a great suggestion, it does look more concise. I will change it 
in v3, thanks!

> thanks,
> jirka
> 
> 
>>
>> Signed-off-by: Tao Chen <chen.dylane@linux.dev>
>> ---
>>   kernel/trace/bpf_trace.c | 48 ++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 48 insertions(+)
>>
>> Change list:
>>    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..9a8ca8a8e2b 100644
>> --- a/kernel/trace/bpf_trace.c
>> +++ b/kernel/trace/bpf_trace.c
>> @@ -3157,10 +3157,58 @@ 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);
>> +
>> +	for (int i = 0; i < umulti_link->cnt; i++) {
>> +		seq_printf(seq,
>> +			   "offset:\t%#llx\n"
>> +			   "ref_ctr_offset:\t%#lx\n"
>> +			   "cookie:\t%llu\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
>>


-- 
Best Regards
Tao Chen