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| author | Jiri Olsa <jolsa@kernel.org> | 2020-08-25 21:21:21 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-08-26 00:41:15 +0200 |
| commit | 68a26bc7922ebf8bbf418f8e9d69364d965433e9 (patch) | |
| tree | 935ad42f80bdc1ebc4e08eada4b472d02c3e44d3 /Documentation/bpf | |
| parent | bpf: Add d_path helper (diff) | |
| download | linux-68a26bc7922ebf8bbf418f8e9d69364d965433e9.tar.xz linux-68a26bc7922ebf8bbf418f8e9d69364d965433e9.zip | |
bpf: Update .BTF_ids section in btf.rst with sets info
Updating btf.rst doc with info about BTF_SET_START/END macros.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200825192124.710397-12-jolsa@kernel.org
Diffstat (limited to 'Documentation/bpf')
| -rw-r--r-- | Documentation/bpf/btf.rst | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst index b5361b8621c9..44dc789de2b4 100644 --- a/Documentation/bpf/btf.rst +++ b/Documentation/bpf/btf.rst @@ -724,6 +724,31 @@ want to define unused entry in BTF_ID_LIST, like:: BTF_ID_UNUSED BTF_ID(struct, task_struct) +The ``BTF_SET_START/END`` macros pair defines sorted list of BTF ID values +and their count, with following syntax:: + + BTF_SET_START(set) + BTF_ID(type1, name1) + BTF_ID(type2, name2) + BTF_SET_END(set) + +resulting in following layout in .BTF_ids section:: + + __BTF_ID__set__set: + .zero 4 + __BTF_ID__type1__name1__3: + .zero 4 + __BTF_ID__type2__name2__4: + .zero 4 + +The ``struct btf_id_set set;`` variable is defined to access the list. + +The ``typeX`` name can be one of following:: + + struct, union, typedef, func + +and is used as a filter when resolving the BTF ID value. + All the BTF ID lists and sets are compiled in the .BTF_ids section and resolved during the linking phase of kernel build by ``resolve_btfids`` tool. |