bpf: Rename BTF_KIND_TAG to BTF_KIND_DECL_TAG

Patch set [1] introduced BTF_KIND_TAG to allow tagging
declarations for struct/union, struct/union field, var, func
and func arguments and these tags will be encoded into
dwarf. They are also encoded to btf by llvm for the bpf target.

After BTF_KIND_TAG is introduced, we intended to use it
for kernel __user attributes. But kernel __user is actually
a type attribute. Upstream and internal discussion showed
it is not a good idea to mix declaration attribute and
type attribute. So we proposed to introduce btf_type_tag
as a type attribute and existing btf_tag renamed to
btf_decl_tag ([2]).

This patch renamed BTF_KIND_TAG to BTF_KIND_DECL_TAG and some
other declarations with *_tag to *_decl_tag to make it clear
the tag is for declaration. In the future, BTF_KIND_TYPE_TAG
might be introduced per [3].

 [1] https://lore.kernel.org/bpf/20210914223004.244411-1-yhs@fb.com/
 [2] https://reviews.llvm.org/D111588
 [3] https://reviews.llvm.org/D111199

Fixes: b5ea834dde6b ("bpf: Support for new btf kind BTF_KIND_TAG")
Fixes: 5b84bd10363e ("libbpf: Add support for BTF_KIND_TAG")
Fixes: 5c07f2fec003 ("bpftool: Add support for BTF_KIND_TAG")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211012164838.3345699-1-yhs@fb.com

1 files changed, 12 insertions, 12 deletions

diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
index 1bfe4072f5fc..9e5b4a98af76 100644
--- a/Documentation/bpf/btf.rst
+++ b/Documentation/bpf/btf.rst
@@ -85,7 +85,7 @@ sequentially and type id is assigned to each recognized type starting from id
     #define BTF_KIND_VAR            14      /* Variable     */
     #define BTF_KIND_DATASEC        15      /* Section      */
     #define BTF_KIND_FLOAT          16      /* Floating point       */
-    #define BTF_KIND_TAG            17      /* Tag          */
+    #define BTF_KIND_DECL_TAG       17      /* Decl 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 +107,7 @@ 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 TAG.
+         * FUNC, FUNC_PROTO and DECL_TAG.
          * "type" is a type_id referring to another type.
          */
         union {
@@ -466,30 +466,30 @@ map definition.
 
 No additional type data follow ``btf_type``.
 
-2.2.17 BTF_KIND_TAG
-~~~~~~~~~~~~~~~~~~~
+2.2.17 BTF_KIND_DECL_TAG
+~~~~~~~~~~~~~~~~~~~~~~~~
 
 ``struct btf_type`` encoding requirement:
  * ``name_off``: offset to a non-empty string
  * ``info.kind_flag``: 0
- * ``info.kind``: BTF_KIND_TAG
+ * ``info.kind``: BTF_KIND_DECL_TAG
  * ``info.vlen``: 0
  * ``type``: ``struct``, ``union``, ``func`` or ``var``
 
-``btf_type`` is followed by ``struct btf_tag``.::
+``btf_type`` is followed by ``struct btf_decl_tag``.::
 
-    struct btf_tag {
+    struct btf_decl_tag {
         __u32   component_idx;
     };
 
-The ``name_off`` encodes btf_tag attribute string.
+The ``name_off`` encodes btf_decl_tag attribute string.
 The ``type`` should be ``struct``, ``union``, ``func`` or ``var``.
-For ``var`` type, ``btf_tag.component_idx`` must be ``-1``.
-For the other three types, if the btf_tag attribute is
+For ``var`` type, ``btf_decl_tag.component_idx`` must be ``-1``.
+For the other three types, if the btf_decl_tag attribute is
 applied to the ``struct``, ``union`` or ``func`` itself,
-``btf_tag.component_idx`` must be ``-1``. Otherwise,
+``btf_decl_tag.component_idx`` must be ``-1``. Otherwise,
 the attribute is applied to a ``struct``/``union`` member or
-a ``func`` argument, and ``btf_tag.component_idx`` should be a
+a ``func`` argument, and ``btf_decl_tag.component_idx`` should be a
 valid index (starting from 0) pointing to a member or an argument.
 
 3. BTF Kernel API