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@xxxxxxxxx>
> > ---
> >   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