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libbpf: Add debug messaging in dedup equivalence/identity matching #6404

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libbpf: Add debug messaging in dedup equivalence/identity matching #6404

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36 changes: 31 additions & 5 deletions tools/lib/bpf/btf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4431,11 +4431,14 @@ static bool btf_dedup_identical_types(struct btf_dedup *d, __u32 id1, __u32 id2,
struct btf_type *t1, *t2;
int k1, k2;
recur:
if (depth <= 0)
return false;

t1 = btf_type_by_id(d->btf, id1);
t2 = btf_type_by_id(d->btf, id2);
if (depth <= 0) {
pr_debug("Reached depth limit for identical type comparison for '%s'/'%s'\n",
btf__name_by_offset(d->btf, t1->name_off),
btf__name_by_offset(d->btf, t2->name_off));
return false;
}

k1 = btf_kind(t1);
k2 = btf_kind(t2);
Expand Down Expand Up @@ -4497,8 +4500,18 @@ static bool btf_dedup_identical_types(struct btf_dedup *d, __u32 id1, __u32 id2,
for (i = 0, n = btf_vlen(t1); i < n; i++, m1++, m2++) {
if (m1->type == m2->type)
continue;
if (!btf_dedup_identical_types(d, m1->type, m2->type, depth - 1))
if (!btf_dedup_identical_types(d, m1->type, m2->type, depth - 1)) {
/* provide debug message for named types. */
if (t1->name_off) {
pr_debug("%s '%s' (size %d vlen %d) appears equal but differs for %d-indexed members '%s'/'%s'\n",
k1 == BTF_KIND_STRUCT ? "struct" : "union",
btf__name_by_offset(d->btf, t1->name_off),
t1->size, btf_vlen(t1), i,
btf__name_by_offset(d->btf, m1->name_off),
btf__name_by_offset(d->btf, m2->name_off));
}
return false;
}
}
return true;
}
Expand Down Expand Up @@ -4739,8 +4752,21 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
canon_m = btf_members(canon_type);
for (i = 0; i < vlen; i++) {
eq = btf_dedup_is_equiv(d, cand_m->type, canon_m->type);
if (eq <= 0)
if (eq <= 0) {
/* provide debug message for named types only;
* too many anon struct/unions match.
*/
if (cand_type->name_off) {
pr_debug("%s '%s' (size %d vlen %d) appears equivalent but differs for %d-indexed cand/canon member '%s'/'%s': %d\n",
cand_kind == BTF_KIND_STRUCT ? "struct" : "union",
btf__name_by_offset(d->btf, cand_type->name_off),
vlen, cand_type->size, i,
btf__name_by_offset(d->btf, cand_m->name_off),
btf__name_by_offset(d->btf, canon_m->name_off),
eq);
}
return eq;
}
cand_m++;
canon_m++;
}
Expand Down
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