linux-kernel - Re: [PATCH bpf-next v2 2/2] bpf: Add show_fdinfo for kprobe

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aE_KaH3DAo4-Yq7m@krava>
Date: Mon, 16 Jun 2025 09:40:24 +0200
From: Jiri Olsa <olsajiri@...il.com>
To: Tao Chen <chen.dylane@...ux.dev>
Cc: song@...nel.org, kpsingh@...nel.org, mattbobrowski@...gle.com,
	ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
	martin.lau@...ux.dev, eddyz87@...il.com, yonghong.song@...ux.dev,
	john.fastabend@...il.com, sdf@...ichev.me, haoluo@...gle.com,
	rostedt@...dmis.org, mhiramat@...nel.org,
	mathieu.desnoyers@...icios.com, bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next v2 2/2] bpf: Add show_fdinfo for kprobe_multi

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@...ux.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
>