diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index b6be579e0dc6..e97217a77196 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -3477,8 +3477,8 @@ static long btf_hash_struct(struct btf_type *t) } /* - * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type - * IDs. This check is performed during type graph equivalence check and + * Check structural compatibility of two STRUCTs/UNIONs, ignoring referenced + * type IDs. This check is performed during type graph equivalence check and * referenced types equivalence is checked separately. */ static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2) @@ -3851,6 +3851,31 @@ static int btf_dedup_identical_arrays(struct btf_dedup *d, __u32 id1, __u32 id2) return btf_equal_array(t1, t2); } +/* Check if given two types are identical STRUCT/UNION definitions */ +static bool btf_dedup_identical_structs(struct btf_dedup *d, __u32 id1, __u32 id2) +{ + const struct btf_member *m1, *m2; + struct btf_type *t1, *t2; + int n, i; + + t1 = btf_type_by_id(d->btf, id1); + t2 = btf_type_by_id(d->btf, id2); + + if (!btf_is_composite(t1) || btf_kind(t1) != btf_kind(t2)) + return false; + + if (!btf_shallow_equal_struct(t1, t2)) + return false; + + m1 = btf_members(t1); + m2 = btf_members(t2); + for (i = 0, n = btf_vlen(t1); i < n; i++, m1++, m2++) { + if (m1->type != m2->type) + return false; + } + return true; +} + /* * 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 @@ -3962,6 +3987,8 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id, hypot_type_id = d->hypot_map[canon_id]; if (hypot_type_id <= BTF_MAX_NR_TYPES) { + if (hypot_type_id == cand_id) + return 1; /* 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 @@ -3970,8 +3997,18 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id, * 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_identical_arrays(d, hypot_type_id, cand_id)) + return 1; + /* It turns out that similar situation can happen with + * struct/union sometimes, sigh... Handle the case where + * structs/unions are exactly the same, down to the referenced + * type IDs. Anything more complicated (e.g., if referenced + * types are different, but equivalent) is *way more* + * complicated and requires a many-to-many equivalence mapping. + */ + if (btf_dedup_identical_structs(d, hypot_type_id, cand_id)) + return 1; + return 0; } if (btf_dedup_hypot_map_add(d, canon_id, cand_id))