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

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Message-ID: <029e657a-cbf5-4db1-9ddb-5fbf75ea8f4e@linux.dev>
Date: Tue, 3 Jun 2025 23:07:03 +0800
From: Tao Chen <chen.dylane@...ux.dev>
To: 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, jolsa@...nel.org
Cc: 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

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.

> 
>> +            __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