Commit d52f5c63 authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

docs/bpf: Update documentation for BTF_KIND_TYPE_TAG support 



Add BTF_KIND_TYPE_TAG documentation in btf.rst.

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211112012656.1509082-1-yhs@fb.com
parent 3f1d0dc0

Documentation/bpf/btf.rst

+12 −1
Original line number Diff line number Diff line
@@ -86,6 +86,7 @@ sequentially and type id is assigned to each recognized type starting from id 
    #define BTF_KIND_DATASEC        15      /* Section      */

    #define BTF_KIND_FLOAT          16      /* Floating point       */

    #define BTF_KIND_DECL_TAG       17      /* Decl Tag     */

    #define BTF_KIND_TYPE_TAG       18      /* Type Tag     */



Note that the type section encodes debug info, not just pure types.

``BTF_KIND_FUNC`` is not a type, and it represents a defined subprogram.
@@ -107,7 +108,7 @@ Each type contains the following common data:: 
         * "size" tells the size of the type it is describing.

         *

         * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,

         * FUNC, FUNC_PROTO and DECL_TAG.

         * FUNC, FUNC_PROTO, DECL_TAG and TYPE_TAG.

         * "type" is a type_id referring to another type.

         */

        union {
@@ -492,6 +493,16 @@ the attribute is applied to a ``struct``/``union`` member or 
a ``func`` argument, and ``btf_decl_tag.component_idx`` should be a

valid index (starting from 0) pointing to a member or an argument.



2.2.17 BTF_KIND_TYPE_TAG

~~~~~~~~~~~~~~~~~~~~~~~~



``struct btf_type`` encoding requirement:

 * ``name_off``: offset to a non-empty string

 * ``info.kind_flag``: 0

 * ``info.kind``: BTF_KIND_TYPE_TAG

 * ``info.vlen``: 0

 * ``type``: the type with ``btf_type_tag`` attribute



3. BTF Kernel API

*****************