On Tue, Oct 4, 2022 at 6:18 AM Roberto Sassu
<roberto.sassu@xxxxxxxxxxxxxxx> wrote:
>
> From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
>
> Introduce bpf_btf_get_fd_by_id_opts(), for symmetry with
> bpf_map_get_fd_by_id_opts(), to let the caller pass the newly introduced
> data structure bpf_get_fd_opts. Keep the existing bpf_btf_get_fd_by_id(),
> and call bpf_btf_get_fd_by_id_opts() with NULL as opts argument, to prevent
> setting open_flags.
>
> Currently, the kernel does not support non-zero open_flags for
> bpf_btf_get_fd_by_id_opts(), and a call with them will result in an error
> returned by the bpf() system call. The caller should always pass zero
> open_flags.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
> ---
> tools/lib/bpf/bpf.c | 12 +++++++++++-
> tools/lib/bpf/bpf.h | 2 ++
> tools/lib/bpf/libbpf.map | 1 +
> 3 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index 92464c2d1da7..f43e8c8afbd3 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -980,19 +980,29 @@ int bpf_map_get_fd_by_id(__u32 id)
> return bpf_map_get_fd_by_id_opts(id, NULL);
> }
>
> -int bpf_btf_get_fd_by_id(__u32 id)
> +int bpf_btf_get_fd_by_id_opts(__u32 id,
> + const struct bpf_get_fd_opts *opts)
> {
> const size_t attr_sz = offsetofend(union bpf_attr, open_flags);
> union bpf_attr attr;
> int fd;
>
> + if (!OPTS_VALID(opts, bpf_get_fd_opts))
> + return libbpf_err(-EINVAL);
> +
> memset(&attr, 0, attr_sz);
> attr.btf_id = id;
> + attr.open_flags = OPTS_GET(opts, open_flags, 0);
>
> fd = sys_bpf_fd(BPF_BTF_GET_FD_BY_ID, &attr, attr_sz);
> return libbpf_err_errno(fd);
> }
>
> +int bpf_btf_get_fd_by_id(__u32 id)
> +{
> + return bpf_btf_get_fd_by_id_opts(id, NULL);
> +}
> +
> int bpf_link_get_fd_by_id(__u32 id)
> {
> const size_t attr_sz = offsetofend(union bpf_attr, open_flags);
> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
> index 595d342fb7f9..559af0b84299 100644
> --- a/tools/lib/bpf/bpf.h
> +++ b/tools/lib/bpf/bpf.h
> @@ -379,6 +379,8 @@ LIBBPF_API int bpf_prog_get_fd_by_id(__u32 id);
> LIBBPF_API int bpf_map_get_fd_by_id_opts(__u32 id,
> const struct bpf_get_fd_opts *opts);
> LIBBPF_API int bpf_map_get_fd_by_id(__u32 id);
> +LIBBPF_API int bpf_btf_get_fd_by_id_opts(__u32 id,
> + const struct bpf_get_fd_opts *opts);
It's subjective, but opts variants of APIs, being more "advanced"
usually are listed after their simpler non-opts variants. Can you
please add new _opts APIs after their non-opts variants?
> LIBBPF_API int bpf_btf_get_fd_by_id(__u32 id);
> LIBBPF_API int bpf_link_get_fd_by_id(__u32 id);
> LIBBPF_API int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len);
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index c3604eaa220d..7011d5eec67b 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -371,6 +371,7 @@ LIBBPF_1.0.0 {
>
> LIBBPF_1.1.0 {
> global:
> + bpf_btf_get_fd_by_id_opts;
> bpf_map_get_fd_by_id_opts;
> bpf_prog_get_fd_by_id_opts;
> user_ring_buffer__discard;
> --
> 2.25.1
>
