Commit d5caef5b authored Feb 04, 2019 by Andrii Nakryiko Committed by Daniel Borkmann Feb 05, 2019

btf: add BTF types deduplication algorithm

This patch implements BTF types deduplication algorithm. It allows to
greatly compress typical output of pahole's DWARF-to-BTF conversion or
LLVM's compilation output by detecting and collapsing identical types emitted in
isolation per compilation unit. Algorithm also resolves struct/union forward
declarations into concrete BTF types representing referenced struct/union. If
undesired, this resolution can be disabled through specifying corresponding options.

Algorithm itself and its application to Linux kernel's BTF types is
described in details at:
https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

parent 69eaab04

tools/lib/bpf/btf.c

+1741 −0

File changed.

Preview size limit exceeded, changes collapsed.

tools/lib/bpf/btf.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -84,6 +84,13 @@ LIBBPF_API int btf_ext__reloc_line_info(const struct btf *btf,
		LIBBPF_API __u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext);
		LIBBPF_API __u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext);

		struct btf_dedup_opts {
		bool dont_resolve_fwds;
		};

		LIBBPF_API int btf__dedup(struct btf btf, struct btf_ext btf_ext,
		const struct btf_dedup_opts *opts);

		#ifdef __cplusplus
		} /* extern "C" */
		#endif

tools/lib/bpf/libbpf.map

+1 −0

Original line number	Diff line number	Diff line
		@@ -133,6 +133,7 @@ LIBBPF_0.0.2 {
		bpf_map_lookup_elem_flags;
		bpf_object__find_map_fd_by_name;
		bpf_get_link_xdp_id;
		btf__dedup;
		btf__get_map_kv_tids;
		btf_ext__free;
		btf_ext__func_info_rec_size;