From 223f903e9c832699f4e5f422281a60756c1c6cfe Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Tue, 12 Oct 2021 09:48:38 -0700 Subject: 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 Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20211012164838.3345699-1-yhs@fb.com --- Documentation/bpf/btf.rst | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) (limited to 'Documentation/bpf/btf.rst') 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 -- cgit