On Thu, Oct 14, 2021 at 2:20 PM Ian Rogers <irogers@xxxxxxxxxx> wrote:
>
> BTF_KIND_TAG is present in libbtf 6.0 but not libbtf in 5.15rc4. Make
> the code requiring it conditionally compiled in.
>
> Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> ---
> btf_encoder.c | 7 +++++++
> lib/bpf | 2 +-
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/btf_encoder.c b/btf_encoder.c
> index c341f95..400d64b 100644
> --- a/btf_encoder.c
> +++ b/btf_encoder.c
> @@ -141,7 +141,9 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = {
> [BTF_KIND_VAR] = "VAR",
> [BTF_KIND_DATASEC] = "DATASEC",
> [BTF_KIND_FLOAT] = "FLOAT",
> +#ifdef BTF_KIND_TAG /* BTF_KIND_TAG was added in 6.0 */
> [BTF_KIND_TAG] = "TAG",
> +#endif
> };
>
> static const char *btf__printable_name(const struct btf *btf, uint32_t offset)
> @@ -648,6 +650,7 @@ static int32_t btf_encoder__add_datasec(struct btf_encoder *encoder, const char
> static int32_t btf_encoder__add_tag(struct btf_encoder *encoder, const char *value, uint32_t type,
> int component_idx)
> {
> +#ifdef BTF_KIND_TAG /* Proxy for libbtf 6.0 */
How will this work when libbpf is loaded dynamically? I believe pahole
has this mode as well.
Also, note that libbpf now provides LIBBPF_MAJOR_VERSION and
LIBBPF_MINOR_VERSION macros, starting from 0.5, so no need for
guessing the version
> struct btf *btf = encoder->btf;
> const struct btf_type *t;
> int32_t id;
> @@ -663,6 +666,10 @@ static int32_t btf_encoder__add_tag(struct btf_encoder *encoder, const char *val
> }
>
> return id;
> +#else
> + fprintf(stderr, "error: unable to encode BTF_KIND_TAG due to old libbtf\n");
> + return -ENOTSUP;
> +#endif
> }
>
> /*
> diff --git a/lib/bpf b/lib/bpf
> index 980777c..986962f 160000
> --- a/lib/bpf
> +++ b/lib/bpf
> @@ -1 +1 @@
> -Subproject commit 980777cc16db75d5628a537c892aefc2640bb242
> +Subproject commit 986962fade5dfa89c2890f3854eb040d2a64ab38
> --
> 2.33.0.1079.g6e70778dc9-goog
>
