linux-kernel - Re: [PATCH bpf-next v2 1/3] bpf: Add cookie to raw_tp bpf_link

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Message-ID: <aD8e6BU1qMeQFay0@krava>
Date: Tue, 3 Jun 2025 18:12:24 +0200
From: Jiri Olsa <olsajiri@...il.com>
To: Tao Chen <chen.dylane@...ux.dev>
Cc: Yonghong Song <yonghong.song@...ux.dev>, ast@...nel.org,
	daniel@...earbox.net, andrii@...nel.org, martin.lau@...ux.dev,
	eddyz87@...il.com, song@...nel.org, john.fastabend@...il.com,
	kpsingh@...nel.org, sdf@...ichev.me, qmo@...nel.org,
	bpf@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next v2 1/3] bpf: Add cookie to raw_tp bpf_link_info

On Tue, Jun 03, 2025 at 11:07:03PM +0800, Tao Chen wrote:
> 在 2025/6/3 22:52, Yonghong Song 写道:
> > 
> > 
> > On 6/2/25 7:26 PM, Tao Chen wrote:
> > > After commit 68ca5d4eebb8 ("bpf: support BPF cookie in raw tracepoint
> > > (raw_tp, tp_btf) programs"), we can show the cookie in bpf_link_info
> > > like kprobe etc.
> > > 
> > > Signed-off-by: Tao Chen <chen.dylane@...ux.dev>
> > > ---
> > >   include/uapi/linux/bpf.h       | 2 ++
> > >   kernel/bpf/syscall.c           | 1 +
> > >   tools/include/uapi/linux/bpf.h | 2 ++
> > >   3 files changed, 5 insertions(+)
> > > 
> > > Change list:
> > > - v1 -> v2:
> > >      - fill the hole in bpf_link_info.(Jiri)
> > > - v1:
> > >      https://lore.kernel.org/bpf/20250529165759.2536245-1-
> > > chen.dylane@...ux.dev
> > > 
> > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> > > index 07ee73cdf9..f3e2aae302 100644
> > > --- a/include/uapi/linux/bpf.h
> > > +++ b/include/uapi/linux/bpf.h
> > > @@ -6644,6 +6644,8 @@ struct bpf_link_info {
> > >           struct {
> > >               __aligned_u64 tp_name; /* in/out: tp_name buffer ptr */
> > >               __u32 tp_name_len;     /* in/out: tp_name buffer len */
> > > +            __u32 reserved; /* just fill the hole */
> > 
> > See various examples in uapi/linux/bpf.h, '__u32 :32;' is the preferred
> > apporach to fill the hole.
> 
> Well, it looks better, will change it in v3, thanks.

ugh, sry.. forgot about this one

jirka

> 
> > 
> > > +            __u64 cookie;
> > >           } raw_tracepoint;
> > >           struct {
> > >               __u32 attach_type;
> > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> > > index 9794446bc8..1c3dbe44ac 100644
> > > --- a/kernel/bpf/syscall.c
> > > +++ b/kernel/bpf/syscall.c
> > > @@ -3687,6 +3687,7 @@ static int
> > > bpf_raw_tp_link_fill_link_info(const struct bpf_link *link,
> > >           return -EINVAL;
> > >       info->raw_tracepoint.tp_name_len = tp_len + 1;
> > > +    info->raw_tracepoint.cookie = raw_tp_link->cookie;
> > >       if (!ubuf)
> > >           return 0;
> > > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/
> > > linux/bpf.h
> > > index 07ee73cdf9..f3e2aae302 100644
> > > --- a/tools/include/uapi/linux/bpf.h
> > > +++ b/tools/include/uapi/linux/bpf.h
> > > @@ -6644,6 +6644,8 @@ struct bpf_link_info {
> > >           struct {
> > >               __aligned_u64 tp_name; /* in/out: tp_name buffer ptr */
> > >               __u32 tp_name_len;     /* in/out: tp_name buffer len */
> > > +            __u32 reserved; /* just fill the hole */
> > > +            __u64 cookie;
> > >           } raw_tracepoint;
> > >           struct {
> > >               __u32 attach_type;
> > 
> 
> 
> -- 
> Best Regards
> Tao Chen