Re: [PATCH 0/3] bpf: Store/dump license string for loaded program

[Alexei Starovoitov]

On Wed, Apr 25, 2018 at 12:17:13PM +0200, Jiri Olsa wrote:
> On Mon, Apr 23, 2018 at 02:11:36PM -0600, Alexei Starovoitov wrote:
> > On Mon, Apr 23, 2018 at 08:59:24AM +0200, Jiri Olsa wrote:
> > > hi,
> > > sending the change to store and dump the license
> > > info for loaded BPF programs. It's important for
> > > us get the license info, when investigating on
> > > screwed up machine.
> > 
> > hmm. boolean flag whether bpf prog is gpl or not
> > is already exposed via bpf_prog_info.
> 
> hum, I can't see that (on bpf-next/master)
> would the attached change be ok with you?
> 
> jirka
> 
> 
> ---
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index e6679393b687..2ce9c9d41c2b 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -1062,6 +1062,7 @@ struct bpf_prog_info {
>  	__u32 ifindex;
>  	__u64 netns_dev;
>  	__u64 netns_ino;
> +	__u16 gpl_compatible:1;
>  } __attribute__((aligned(8)));

ahh. I swear there were patches to add it and I thought we accepted them.
Also just noticed that commit 675fc275a3a2d added 4-byte hole in there.
So I'm thinking we can fill the hole with 
 	__u32 ifindex;
+	__u32 gpl_compatible:1;
 	__u64 netns_dev;
 	__u64 netns_ino;

and keep adding bit fields in there without breaking user space.
Such patch would need to go to bpf tree.