This patch series extends BPF Type Format (BTF) to support arbitrary __attribute__ encoding. Setting the kind_flag to 1 in BTF type tags and decl tags now changes the meaning for the encoded tag, in particular with respect to btf_dump in libbpf. If the kflag is set, then the string encoded by the tag represents the full attribute-list of an attribute specifier [1]. This feature will allow extending tools such as pahole and bpftool to capture and use more granular type information, and make it easier to manage compatibility between clang and gcc BPF compilers. [1] https://gcc.gnu.org/onlinedocs/gcc-13.2.0/gcc/Attribute-Syntax.html v1->v2: - When checking for specific BTF tags in the verifier, make sure the tag's kflag is 0 - Split docs and libbpf changes into separate patches - Various renames, as suggested by Andrii and Eduard v1: https://lore.kernel.org/bpf/20250122025308.2717553-1-ihor.solodrai@xxxxx Ihor Solodrai (6): libbpf: introduce kflag for type_tags and decl_tags in BTF docs/bpf: document the semantics of BTF tags with kind_flag libbpf: check the kflag of type tags in btf_dump selftests/bpf: add a btf_dump test for type_tags bpf: allow kind_flag for BTF type and decl tags selftests/bpf: add a BTF verification test for kflagged type_tag Documentation/bpf/btf.rst | 25 ++- include/uapi/linux/btf.h | 3 +- kernel/bpf/btf.c | 26 ++-- tools/include/uapi/linux/btf.h | 3 +- tools/lib/bpf/btf.c | 86 +++++++--- tools/lib/bpf/btf.h | 3 + tools/lib/bpf/btf_dump.c | 5 +- tools/lib/bpf/libbpf.map | 2 + tools/testing/selftests/bpf/prog_tests/btf.c | 23 ++- .../selftests/bpf/prog_tests/btf_dump.c | 147 +++++++++++++----- tools/testing/selftests/bpf/test_btf.h | 6 + 11 files changed, 244 insertions(+), 85 deletions(-) -- 2.48.1
