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

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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@xxxxxxxxx>
---
  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@xxxxxxxxx

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




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