diff options
| author | Andrii Nakryiko <andrii@kernel.org> | 2020-11-04 20:33:59 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-11-05 18:37:30 -0800 |
| commit | 6b6e6b1d09aa20c351a1fce0ea6402da436624a4 (patch) | |
| tree | ce2216a56c34da099693b7162eb7bef8e1d3f8aa /tools/lib | |
| parent | f86524efcf9e3f3a7cf75ebcd82cf8f58ec716cc (diff) | |
libbpf: Accomodate DWARF/compiler bug with duplicated identical arrays
In some cases compiler seems to generate distinct DWARF types for identical
arrays within the same CU. That seems like a bug, but it's already out there
and breaks type graph equivalence checks, so accommodate it anyway by checking
for identical arrays, regardless of their type ID.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20201105043402.2530976-10-andrii@kernel.org
Diffstat (limited to 'tools/lib')
| -rw-r--r-- | tools/lib/bpf/btf.c | 27 |
1 files changed, 25 insertions, 2 deletions
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 8d04d9becb67..2d0d064c6d31 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -3785,6 +3785,19 @@ static inline __u16 btf_fwd_kind(struct btf_type *t) return btf_kflag(t) ? BTF_KIND_UNION : BTF_KIND_STRUCT; } +/* Check if given two types are identical ARRAY definitions */ +static int btf_dedup_identical_arrays(struct btf_dedup *d, __u32 id1, __u32 id2) +{ + struct btf_type *t1, *t2; + + t1 = btf_type_by_id(d->btf, id1); + t2 = btf_type_by_id(d->btf, id2); + if (!btf_is_array(t1) || !btf_is_array(t2)) + return 0; + + return btf_equal_array(t1, t2); +} + /* * Check equivalence of BTF type graph formed by candidate struct/union (we'll * call it "candidate graph" in this description for brevity) to a type graph @@ -3895,8 +3908,18 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id, canon_id = resolve_fwd_id(d, canon_id); hypot_type_id = d->hypot_map[canon_id]; - if (hypot_type_id <= BTF_MAX_NR_TYPES) - return hypot_type_id == cand_id; + if (hypot_type_id <= BTF_MAX_NR_TYPES) { + /* In some cases compiler will generate different DWARF types + * for *identical* array type definitions and use them for + * different fields within the *same* struct. This breaks type + * equivalence check, which makes an assumption that candidate + * types sub-graph has a consistent and deduped-by-compiler + * types within a single CU. So work around that by explicitly + * allowing identical array types here. + */ + return hypot_type_id == cand_id || + btf_dedup_identical_arrays(d, hypot_type_id, cand_id); + } if (btf_dedup_hypot_map_add(d, canon_id, cand_id)) return -ENOMEM; |