On Mon, Sep 13, 2021 at 8:51 AM Yonghong Song <yhs@xxxxxx> wrote:
>
> Added bpftool support to dump BTF_KIND_TAG information.
> The new bpftool will be used in later patches to dump
> btf in the test bpf program object file.
>
> Currently, the tags are not emitted with
> bpftool btf dump file <path> format c
> and they are silently ignored. The tag information is
> mostly used in the kernel for verification purpose and the kernel
> uses its own btf to check. With adding these tags
> to vmlinux.h, tags will be encoded in program's btf but
> they will not be used by the kernel, at least for now.
> So let us delay adding these tags to format C header files
> until there is a real need.
>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> tools/bpf/bpftool/btf.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
> index f7e5ff3586c9..49743ad96851 100644
> --- a/tools/bpf/bpftool/btf.c
> +++ b/tools/bpf/bpftool/btf.c
> @@ -37,6 +37,7 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = {
> [BTF_KIND_VAR] = "VAR",
> [BTF_KIND_DATASEC] = "DATASEC",
> [BTF_KIND_FLOAT] = "FLOAT",
> + [BTF_KIND_TAG] = "TAG",
> };
>
> struct btf_attach_table {
> @@ -347,6 +348,17 @@ static int dump_btf_type(const struct btf *btf, __u32 id,
> printf(" size=%u", t->size);
> break;
> }
> + case BTF_KIND_TAG: {
> + const struct btf_tag *tag = (const void *)(t + 1);
> +
> + if (json_output) {
> + jsonw_uint_field(w, "type_id", t->type);
> + jsonw_int_field(w, "component_idx", tag->component_idx);
> + } else {
> + printf(" type_id=%u component_idx=%d", t->type, tag->component_idx);
> + }
> + break;
> + }
> default:
> break;
> }
> --
> 2.30.2
>
