Re: [PATCH bpf-next 1/2] tools/lib/bpf: bpf_program__insns allow to retrieve insns in libbpf

[Quentin Monnet <quentin@isovalent.com>]

2021-07-13 20:33 UTC+0200 ~ Lorenzo Fontana <fontanalorenz@gmail.com>
> This allows consumers of libbpf to iterate trough the insns
> of a program without loading it first directly after the ELF parsing.
> 
> Being able to do that is useful to create tooling that can show
> the structure of a BPF program using libbpf without having to
> parse the ELF separately.
> 
> Usage:
>   struct bpf_insn *insn;
>   insn = bpf_program__insns(prog);
> 
> Signed-off-by: Lorenzo Fontana <fontanalorenz@gmail.com>
> ---
>  tools/lib/bpf/libbpf.c | 5 +++++
>  tools/lib/bpf/libbpf.h | 1 +
>  2 files changed, 6 insertions(+)
> 
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 1e04ce724240..67d51531f6b6 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -8866,6 +8866,11 @@ void *bpf_program__priv(const struct bpf_program *prog)
>  	return prog ? prog->priv : libbpf_err_ptr(-EINVAL);
>  }
>  
> +struct bpf_insn *bpf_program__insns(const struct bpf_program *prog)
> +{
> +	return prog ? prog->insns : libbpf_err_ptr(-EINVAL);
> +}
> +
>  void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex)
>  {
>  	prog->prog_ifindex = ifindex;
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index 6e61342ba56c..e4a1c98ae6d9 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -195,6 +195,7 @@ typedef void (*bpf_program_clear_priv_t)(struct bpf_program *, void *);
>  LIBBPF_API int bpf_program__set_priv(struct bpf_program *prog, void *priv,
>  				     bpf_program_clear_priv_t clear_priv);
>  
> +LIBBPF_API struct bpf_insn *bpf_program__insns(const struct bpf_program *prog);
>  LIBBPF_API void *bpf_program__priv(const struct bpf_program *prog);
>  LIBBPF_API void bpf_program__set_ifindex(struct bpf_program *prog,
>  					 __u32 ifindex);
> 

If you make it part of the API, the new function should also have an
entry in tools/lib/bpf/libbpf.map.

Quentin