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btf: add BTF types deduplication algorithm

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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>
This commit is contained in:
Andrii Nakryiko 2019-02-04 17:29:45 -08:00 committed by Daniel Borkmann
parent 69eaab04c6
commit d5caef5b56
3 changed files with 1749 additions and 0 deletions
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1741
tools/lib/bpf/btf.c
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File diff suppressed because it is too large Load Diff

7
tools/lib/bpf/btf.h
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@ -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

1
tools/lib/bpf/libbpf.map
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@ -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;