[PATCH bpf-next v4 06/18] libbpf: Add enum64 deduplication support

[Yonghong Song <yhs@xxxxxx>]

Add enum64 deduplication support. BTF_KIND_ENUM64 handling
is very similar to BTF_KIND_ENUM.

Signed-off-by: Yonghong Song <yhs@xxxxxx>
---
 tools/lib/bpf/btf.c | 62 +++++++++++++++++++++++++++++++++++++++++++--
 tools/lib/bpf/btf.h |  5 ++++
 2 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 8676efb2baba..ae1520f7e1b0 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -3582,7 +3582,7 @@ static bool btf_equal_int_tag(struct btf_type *t1, struct btf_type *t2)
 	return info1 == info2;
 }
 
-/* Calculate type signature hash of ENUM. */
+/* Calculate type signature hash of ENUM/ENUM64. */
 static long btf_hash_enum(struct btf_type *t)
 {
 	long h;
@@ -3616,9 +3616,31 @@ static bool btf_equal_enum(struct btf_type *t1, struct btf_type *t2)
 	return true;
 }
 
+static bool btf_equal_enum64(struct btf_type *t1, struct btf_type *t2)
+{
+	const struct btf_enum64 *m1, *m2;
+	__u16 vlen;
+	int i;
+
+	if (!btf_equal_common(t1, t2))
+		return false;
+
+	vlen = btf_vlen(t1);
+	m1 = btf_enum64(t1);
+	m2 = btf_enum64(t2);
+	for (i = 0; i < vlen; i++) {
+		if (m1->name_off != m2->name_off || m1->val_lo32 != m2->val_lo32 ||
+		    m1->val_hi32 != m2->val_hi32)
+			return false;
+		m1++;
+		m2++;
+	}
+	return true;
+}
+
 static inline bool btf_is_enum_fwd(struct btf_type *t)
 {
-	return btf_is_enum(t) && btf_vlen(t) == 0;
+	return btf_is_any_enum(t) && btf_vlen(t) == 0;
 }
 
 static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
@@ -3631,6 +3653,17 @@ static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
 	       t1->size == t2->size;
 }
 
+static bool btf_compat_enum64(struct btf_type *t1, struct btf_type *t2)
+{
+	if (!btf_is_enum_fwd(t1) && !btf_is_enum_fwd(t2))
+		return btf_equal_enum64(t1, t2);
+
+	/* ignore vlen when comparing */
+	return t1->name_off == t2->name_off &&
+	       (t1->info & ~0xffff) == (t2->info & ~0xffff) &&
+	       t1->size == t2->size;
+}
+
 /*
  * Calculate type signature hash of STRUCT/UNION, ignoring referenced type IDs,
  * as referenced type IDs equivalence is established separately during type
@@ -3843,6 +3876,7 @@ static int btf_dedup_prep(struct btf_dedup *d)
 			h = btf_hash_int_decl_tag(t);
 			break;
 		case BTF_KIND_ENUM:
+		case BTF_KIND_ENUM64:
 			h = btf_hash_enum(t);
 			break;
 		case BTF_KIND_STRUCT:
@@ -3932,6 +3966,27 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
 		}
 		break;
 
+	case BTF_KIND_ENUM64:
+		h = btf_hash_enum(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = (__u32)(long)hash_entry->value;
+			cand = btf_type_by_id(d->btf, cand_id);
+			if (btf_equal_enum64(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+			if (btf_compat_enum64(t, cand)) {
+				if (btf_is_enum_fwd(t)) {
+					/* resolve fwd to full enum */
+					new_id = cand_id;
+					break;
+				}
+				/* resolve canonical enum fwd to full enum */
+				d->map[cand_id] = type_id;
+			}
+		}
+		break;
+
 	case BTF_KIND_FWD:
 	case BTF_KIND_FLOAT:
 		h = btf_hash_common(t);
@@ -4227,6 +4282,9 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
 	case BTF_KIND_ENUM:
 		return btf_compat_enum(cand_type, canon_type);
 
+	case BTF_KIND_ENUM64:
+		return btf_compat_enum64(cand_type, canon_type);
+
 	case BTF_KIND_FWD:
 	case BTF_KIND_FLOAT:
 		return btf_equal_common(cand_type, canon_type);
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index a41463bf9060..c7e8b1fdfe24 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -531,6 +531,11 @@ static inline bool btf_is_type_tag(const struct btf_type *t)
 	return btf_kind(t) == BTF_KIND_TYPE_TAG;
 }
 
+static inline bool btf_is_any_enum(const struct btf_type *t)
+{
+	return btf_is_enum(t) || btf_is_enum64(t);
+}
+
 static inline __u8 btf_int_encoding(const struct btf_type *t)
 {
 	return BTF_INT_ENCODING(*(__u32 *)(t + 1));
-- 
2.30.2