From: Yonghong Song <yhs@fb.com>
Date: Thu, 11 Nov 2021 17:26:56 -0800
Subject: docs/bpf: Update documentation for BTF_KIND_TYPE_TAG support
Patch-mainline: v5.17-rc1
Git-commit: d52f5c639dd8605d2563b77b190e278f615a2b8a
References: jsc#PED-1368
Add BTF_KIND_TYPE_TAG documentation in btf.rst.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211112012656.1509082-1-yhs@fb.com
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
Documentation/bpf/btf.rst | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
--- a/Documentation/bpf/btf.rst
+++ b/Documentation/bpf/btf.rst
@@ -86,6 +86,7 @@ sequentially and type id is assigned to
#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
* "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``
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
*****************