Merge branch 'bpf-extend-btf-uapi-vlen-kinds-to-use-unused-bits'

Alan Maguire says:

====================
bpf: Extend BTF UAPI vlen, kinds to use unused bits

Currently BTF types can have a maximum of 65535 vlen-specified
objects.  While this limit has not yet been surpassed for existing
cases (struct/union fields, enum values, function arguments and
datasec), upcoming BTF location information - specifically inline
sites - will hit that limit.  Utilize unused BTF info bits in
struct btf_type to increase limit to 24-bits (over 16 million).
This is more than an order of magnitude greater than inline
site counts for the kernel (~400,000) so should be enough for
the near future at least.

Similarly, struct btf_type uses 5 bits for BTF kind values;
currently we use 20 kinds, but BTF location information will
take another 3, and conceivably providing better support for Rust
types in BTF (now that modules can be built using Rust) could
push us close to the max of 31.  Use 2 unused bits to provide
a max possible kind of 127.

Patch 1 handles UAPI and kernel-related changes.

Patch 2 updates libbpf to have btf_vlen() return a __u32 instead
of __u16 and updates consumers in libbpf accordingly.  Also adds
bounds checking for max vlen.

Patch 3 cleans up __u16 vlen usage in bpftool.

Patch 4 fixes up a test that relies on BTF info overflowing
maximum kind value; fix up the expected error to be an
invalid kind rather than (now impossible) invalid btf_info.

Patch 5 fixes up __u16 vlen usage in selftests/bpf.

Patch 6 syncs BTF documentation with UAPI changes.

Changes since v2 [1]:

- dropped backwards-compatibility macros (Alexei, patch 1)
- added additional vlen bounds check in btf__add_field()
  (sashiko, bpf bot, patch 2)
- dropped sanitization check in libbpf as older kernels will
  reject BTF with extended vlen/kinds using BTF info mask
  (Alexei)
- fix more vlen assumptions in prog_test/ctx_rewrite.c
  (sashiko, patch 5)

Changes since v1 [2]:

- added redundant macros to UAPI in case enum switch for BTF_MAX*
  values causes problems (sashiko, patch 1)
- updated feature test to use BTF loading rather than vmlinux BTF
  lookup, in line with other BTF feature tests (sashiko, patch 3)
- fixed up a few more kernel, libbpf, bpftool instances of __u16 usage
  (bpf bot, sashiko, patches 1, 2, 4)
- fixed up sanitize selftest cleanup (Mykyta, patch 5)
- used unlikely-to-be-used kind (sashiko, patch 6)
- fixed a few lingering selftests uses of __u16 for kind (patch 7)
- update btf.rst with new vlen, kind sizes (patch 8)

[1] https://lore.kernel.org/bpf/20260416143904.1220662-1-alan.maguire@oracle.com/
[2] https://lore.kernel.org/bpf/20260414195019.684531-1-alan.maguire@oracle.com/
====================

Link: https://patch.msgid.link/20260417143023.1551481-1-alan.maguire@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

16 files changed, 119 insertions, 115 deletions

diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
index 3b60583f5db2..3f05f17990ad 100644
--- a/Documentation/bpf/btf.rst
+++ b/Documentation/bpf/btf.rst
@@ -97,10 +97,8 @@ Each type contains the following common data::
     struct btf_type {
         __u32 name_off;
         /* "info" bits arrangement
-         * bits  0-15: vlen (e.g. # of struct's members)
-         * bits 16-23: unused
-         * bits 24-28: kind (e.g. int, ptr, array...etc)
-         * bits 29-30: unused
+         * bits  0-23: vlen (e.g. # of struct's members)
+         * bits 24-30: kind (e.g. int, ptr, array...etc)
          * bit     31: kind_flag, currently used by
          *             struct, union, enum, fwd, enum64,
          *             decl_tag and type_tag
diff --git a/include/linux/btf.h b/include/linux/btf.h
index 48108471c5b1..c82d0d689059 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -415,12 +415,12 @@ static inline bool btf_type_is_array(const struct btf_type *t)
 	return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY;
 }
 
-static inline u16 btf_type_vlen(const struct btf_type *t)
+static inline u32 btf_type_vlen(const struct btf_type *t)
 {
 	return BTF_INFO_VLEN(t->info);
 }
 
-static inline u16 btf_vlen(const struct btf_type *t)
+static inline u32 btf_vlen(const struct btf_type *t)
 {
 	return btf_type_vlen(t);
 }
diff --git a/include/uapi/linux/btf.h b/include/uapi/linux/btf.h
index 638615ebddc2..618167cab4e6 100644
--- a/include/uapi/linux/btf.h
+++ b/include/uapi/linux/btf.h
@@ -33,20 +33,22 @@ struct btf_header {
 	__u32	layout_len;	/* length of layout section	*/
 };
 
-/* Max # of type identifier */
-#define BTF_MAX_TYPE	0x000fffff
-/* Max offset into the string section */
-#define BTF_MAX_NAME_OFFSET	0x00ffffff
-/* Max # of struct/union/enum members or func args */
-#define BTF_MAX_VLEN	0xffff
+enum btf_max {
+	/* Max possible kind */
+	BTF_MAX_KIND =		0x0000007f,
+	/* Max # of type identifier */
+	BTF_MAX_TYPE =		0x000fffff,
+	/* Max offset into the string section */
+	BTF_MAX_NAME_OFFSET =	0x00ffffff,
+	/* Max # of struct/union/enum members or func args */
+	BTF_MAX_VLEN =		0x00ffffff,
+};
 
 struct btf_type {
 	__u32 name_off;
 	/* "info" bits arrangement
-	 * bits  0-15: vlen (e.g. # of struct's members)
-	 * bits 16-23: unused
-	 * bits 24-28: kind (e.g. int, ptr, array...etc)
-	 * bits 29-30: unused
+	 * bits  0-23: vlen (e.g. # of struct's members)
+	 * bits 24-30: kind (e.g. int, ptr, array...etc)
 	 * bit     31: kind_flag, currently used by
 	 *             struct, union, enum, fwd, enum64,
 	 *             decl_tag and type_tag
@@ -65,8 +67,8 @@ struct btf_type {
 	};
 };
 
-#define BTF_INFO_KIND(info)	(((info) >> 24) & 0x1f)
-#define BTF_INFO_VLEN(info)	((info) & 0xffff)
+#define BTF_INFO_KIND(info)	(((info) >> 24) & 0x7f)
+#define BTF_INFO_VLEN(info)	((info) & 0xffffff)
 #define BTF_INFO_KFLAG(info)	((info) >> 31)
 
 enum {
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 3c2aaa3c5004..77af44d8a3ad 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -182,7 +182,6 @@
 #define BITS_ROUNDUP_BYTES(bits) \
 	(BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))
 
-#define BTF_INFO_MASK 0x9f00ffff
 #define BTF_INT_MASK 0x0fffffff
 #define BTF_TYPE_ID_VALID(type_id) ((type_id) <= BTF_MAX_TYPE)
 #define BTF_STR_OFFSET_VALID(name_off) ((name_off) <= BTF_MAX_NAME_OFFSET)
@@ -289,7 +288,7 @@ enum verifier_phase {
 struct resolve_vertex {
 	const struct btf_type *t;
 	u32 type_id;
-	u16 next_member;
+	u32 next_member;
 };
 
 enum visit_state {
@@ -2031,7 +2030,7 @@ static int env_stack_push(struct btf_verifier_env *env,
 }
 
 static void env_stack_set_next_member(struct btf_verifier_env *env,
-				      u16 next_member)
+				      u32 next_member)
 {
 	env->stack[env->top_stack - 1].next_member = next_member;
 }
@@ -3293,7 +3292,7 @@ static s32 btf_struct_check_meta(struct btf_verifier_env *env,
 	struct btf *btf = env->btf;
 	u32 struct_size = t->size;
 	u32 offset;
-	u16 i;
+	u32 i;
 
 	meta_needed = btf_type_vlen(t) * sizeof(*member);
 	if (meta_left < meta_needed) {
@@ -3369,7 +3368,7 @@ static int btf_struct_resolve(struct btf_verifier_env *env,
 {
 	const struct btf_member *member;
 	int err;
-	u16 i;
+	u32 i;
 
 	/* Before continue resolving the next_member,
 	 * ensure the last member is indeed resolved to a
@@ -4447,7 +4446,7 @@ static s32 btf_enum_check_meta(struct btf_verifier_env *env,
 	const struct btf_enum *enums = btf_type_enum(t);
 	struct btf *btf = env->btf;
 	const char *fmt_str;
-	u16 i, nr_enums;
+	u32 i, nr_enums;
 	u32 meta_needed;
 
 	nr_enums = btf_type_vlen(t);
@@ -4555,7 +4554,7 @@ static s32 btf_enum64_check_meta(struct btf_verifier_env *env,
 	const struct btf_enum64 *enums = btf_type_enum64(t);
 	struct btf *btf = env->btf;
 	const char *fmt_str;
-	u16 i, nr_enums;
+	u32 i, nr_enums;
 	u32 meta_needed;
 
 	nr_enums = btf_type_vlen(t);
@@ -4683,7 +4682,7 @@ static void btf_func_proto_log(struct btf_verifier_env *env,
 			       const struct btf_type *t)
 {
 	const struct btf_param *args = (const struct btf_param *)(t + 1);
-	u16 nr_args = btf_type_vlen(t), i;
+	u32 nr_args = btf_type_vlen(t), i;
 
 	btf_verifier_log(env, "return=%u args=(", t->type);
 	if (!nr_args) {
@@ -4929,7 +4928,7 @@ static int btf_datasec_resolve(struct btf_verifier_env *env,
 {
 	const struct btf_var_secinfo *vsi;
 	struct btf *btf = env->btf;
-	u16 i;
+	u32 i;
 
 	env->resolve_mode = RESOLVE_TBD;
 	for_each_vsi_from(i, v->next_member, v->t, vsi) {
@@ -5183,7 +5182,7 @@ static int btf_func_proto_check(struct btf_verifier_env *env,
 	const struct btf_type *ret_type;
 	const struct btf_param *args;
 	const struct btf *btf;
-	u16 nr_args, i;
+	u32 nr_args, i;
 	int err;
 
 	btf = env->btf;
@@ -5278,7 +5277,7 @@ static int btf_func_check(struct btf_verifier_env *env,
 	const struct btf_type *proto_type;
 	const struct btf_param *args;
 	const struct btf *btf;
-	u16 nr_args, i;
+	u32 nr_args, i;
 
 	btf = env->btf;
 	proto_type = btf_type_by_id(btf, t->type);
@@ -5336,12 +5335,6 @@ static s32 btf_check_meta(struct btf_verifier_env *env,
 	}
 	meta_left -= sizeof(*t);
 
-	if (t->info & ~BTF_INFO_MASK) {
-		btf_verifier_log(env, "[%u] Invalid btf_info:%x",
-				 env->log_type_id, t->info);
-		return -EINVAL;
-	}
-
 	if (BTF_INFO_KIND(t->info) > BTF_KIND_MAX ||
 	    BTF_INFO_KIND(t->info) == BTF_KIND_UNKN) {
 		btf_verifier_log(env, "[%u] Invalid kind:%u",
diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c
index 2e899e940034..6ef908adf3a4 100644
--- a/tools/bpf/bpftool/btf.c
+++ b/tools/bpf/bpftool/btf.c
@@ -179,8 +179,7 @@ static int dump_btf_type(const struct btf *btf, __u32 id,
 	case BTF_KIND_STRUCT:
 	case BTF_KIND_UNION: {
 		const struct btf_member *m = (const void *)(t + 1);
-		__u16 vlen = BTF_INFO_VLEN(t->info);
-		int i;
+		__u32 i, vlen = BTF_INFO_VLEN(t->info);
 
 		if (json_output) {
 			jsonw_uint_field(w, "size", t->size);
@@ -225,9 +224,8 @@ static int dump_btf_type(const struct btf *btf, __u32 id,
 	}
 	case BTF_KIND_ENUM: {
 		const struct btf_enum *v = (const void *)(t + 1);
-		__u16 vlen = BTF_INFO_VLEN(t->info);
+		__u32 i, vlen = BTF_INFO_VLEN(t->info);
 		const char *encoding;
-		int i;
 
 		encoding = btf_kflag(t) ? "SIGNED" : "UNSIGNED";
 		if (json_output) {
@@ -263,9 +261,8 @@ static int dump_btf_type(const struct btf *btf, __u32 id,
 	}
 	case BTF_KIND_ENUM64: {
 		const struct btf_enum64 *v = btf_enum64(t);
-		__u16 vlen = btf_vlen(t);
+		__u32 i, vlen = btf_vlen(t);
 		const char *encoding;
-		int i;
 
 		encoding = btf_kflag(t) ? "SIGNED" : "UNSIGNED";
 		if (json_output) {
@@ -325,8 +322,7 @@ static int dump_btf_type(const struct btf *btf, __u32 id,
 	}
 	case BTF_KIND_FUNC_PROTO: {
 		const struct btf_param *p = (const void *)(t + 1);
-		__u16 vlen = BTF_INFO_VLEN(t->info);
-		int i;
+		__u32 i, vlen = BTF_INFO_VLEN(t->info);
 
 		if (json_output) {
 			jsonw_uint_field(w, "ret_type_id", t->type);
@@ -369,8 +365,7 @@ static int dump_btf_type(const struct btf *btf, __u32 id,
 	case BTF_KIND_DATASEC: {
 		const struct btf_var_secinfo *v = (const void *)(t + 1);
 		const struct btf_type *vt;
-		__u16 vlen = BTF_INFO_VLEN(t->info);
-		int i;
+		__u32 i, vlen = BTF_INFO_VLEN(t->info);
 
 		if (json_output) {
 			jsonw_uint_field(w, "size", t->size);
@@ -675,7 +670,7 @@ static __u64 btf_name_hasher(__u64 hash, const struct btf *btf, __u32 name_off)
 static __u64 btf_type_disambig_hash(const struct btf *btf, __u32 id, bool include_members)
 {
 	const struct btf_type *t = btf__type_by_id(btf, id);
-	int i;
+	__u32 i;
 	size_t hash = 0;
 
 	hash = btf_name_hasher(hash, btf, t->name_off);
diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c
index def297e879f4..9dc8425b1789 100644
--- a/tools/bpf/bpftool/btf_dumper.c
+++ b/tools/bpf/bpftool/btf_dumper.c
@@ -150,7 +150,7 @@ static int btf_dumper_enum(const struct btf_dumper *d,
 {
 	const struct btf_enum *enums = btf_enum(t);
 	__s64 value;
-	__u16 i;
+	__u32 i;
 
 	switch (t->size) {
 	case 8:
@@ -189,7 +189,7 @@ static int btf_dumper_enum64(const struct btf_dumper *d,
 	const struct btf_enum64 *enums = btf_enum64(t);
 	__u32 val_lo32, val_hi32;
 	__u64 value;
-	__u16 i;
+	__u32 i;
 
 	value = *(__u64 *)data;
 	val_lo32 = (__u32)value;
diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index 2f9e10752e28..37159e02f418 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -2094,7 +2094,8 @@ btfgen_mark_type(struct btfgen_info *info, unsigned int type_id, bool follow_poi
 	struct btf_type *cloned_type;
 	struct btf_param *param;
 	struct btf_array *array;
-	int err, i;
+	__u32 i;
+	int err;
 
 	if (type_id == 0)
 		return 0;
@@ -2229,7 +2230,8 @@ static int btfgen_mark_type_match(struct btfgen_info *info, __u32 type_id, bool
 	const struct btf_type *btf_type;
 	struct btf *btf = info->src_btf;
 	struct btf_type *cloned_type;
-	int i, err;
+	int err;
+	__u32 i;
 
 	if (type_id == 0)
 		return 0;
@@ -2249,7 +2251,7 @@ static int btfgen_mark_type_match(struct btfgen_info *info, __u32 type_id, bool
 	case BTF_KIND_STRUCT:
 	case BTF_KIND_UNION: {
 		struct btf_member *m = btf_members(btf_type);
-		__u16 vlen = btf_vlen(btf_type);
+		__u32 vlen = btf_vlen(btf_type);
 
 		if (behind_ptr)
 			break;
@@ -2286,7 +2288,7 @@ static int btfgen_mark_type_match(struct btfgen_info *info, __u32 type_id, bool
 		break;
 	}
 	case BTF_KIND_FUNC_PROTO: {
-		__u16 vlen = btf_vlen(btf_type);
+		__u32 vlen = btf_vlen(btf_type);
 		struct btf_param *param;
 
 		/* mark ret type */
@@ -2492,8 +2494,9 @@ static struct btf *btfgen_get_btf(struct btfgen_info *info)
 {
 	struct btf *btf_new = NULL;
 	unsigned int *ids = NULL;
-	unsigned int i, n = btf__type_cnt(info->marked_btf);
+	unsigned int n = btf__type_cnt(info->marked_btf);
 	int err = 0;
+	__u32 i;
 
 	btf_new = btf__new_empty();
 	if (!btf_new) {
@@ -2523,8 +2526,7 @@ static struct btf *btfgen_get_btf(struct btfgen_info *info)
 		/* add members for struct and union */
 		if (btf_is_composite(type)) {
 			struct btf_member *cloned_m, *m;
-			unsigned short vlen;
-			int idx_src;
+			__u32 vlen, idx_src;
 
 			name = btf__str_by_offset(info->src_btf, type->name_off);
 
diff --git a/tools/include/uapi/linux/btf.h b/tools/include/uapi/linux/btf.h
index 638615ebddc2..618167cab4e6 100644
--- a/tools/include/uapi/linux/btf.h
+++ b/tools/include/uapi/linux/btf.h
@@ -33,20 +33,22 @@ struct btf_header {
 	__u32	layout_len;	/* length of layout section	*/
 };
 
-/* Max # of type identifier */
-#define BTF_MAX_TYPE	0x000fffff
-/* Max offset into the string section */
-#define BTF_MAX_NAME_OFFSET	0x00ffffff
-/* Max # of struct/union/enum members or func args */
-#define BTF_MAX_VLEN	0xffff
+enum btf_max {
+	/* Max possible kind */
+	BTF_MAX_KIND =		0x0000007f,
+	/* Max # of type identifier */
+	BTF_MAX_TYPE =		0x000fffff,
+	/* Max offset into the string section */
+	BTF_MAX_NAME_OFFSET =	0x00ffffff,
+	/* Max # of struct/union/enum members or func args */
+	BTF_MAX_VLEN =		0x00ffffff,
+};
 
 struct btf_type {
 	__u32 name_off;
 	/* "info" bits arrangement
-	 * bits  0-15: vlen (e.g. # of struct's members)
-	 * bits 16-23: unused
-	 * bits 24-28: kind (e.g. int, ptr, array...etc)
-	 * bits 29-30: unused
+	 * bits  0-23: vlen (e.g. # of struct's members)
+	 * bits 24-30: kind (e.g. int, ptr, array...etc)
 	 * bit     31: kind_flag, currently used by
 	 *             struct, union, enum, fwd, enum64,
 	 *             decl_tag and type_tag
@@ -65,8 +67,8 @@ struct btf_type {
 	};
 };
 
-#define BTF_INFO_KIND(info)	(((info) >> 24) & 0x1f)
-#define BTF_INFO_VLEN(info)	((info) & 0xffff)
+#define BTF_INFO_KIND(info)	(((info) >> 24) & 0x7f)
+#define BTF_INFO_VLEN(info)	((info) & 0xffffff)
 #define BTF_INFO_KFLAG(info)	((info) >> 31)
 
 enum {
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index ceb57b46a878..267904939098 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -421,7 +421,7 @@ static int btf_type_size_unknown(const struct btf *btf, const struct btf_type *t
 {
 	__u32 l_cnt = btf->hdr.layout_len / sizeof(struct btf_layout);
 	struct btf_layout *l = btf->layout;
-	__u16 vlen = btf_vlen(t);
+	__u32 vlen = btf_vlen(t);
 	__u32 kind = btf_kind(t);
 
 	/* Fall back to base BTF if needed as they share layout information */
@@ -454,7 +454,7 @@ static int btf_type_size_unknown(const struct btf *btf, const struct btf_type *t
 static int btf_type_size(const struct btf *btf, const struct btf_type *t)
 {
 	const int base_size = sizeof(struct btf_type);
-	__u16 vlen = btf_vlen(t);
+	__u32 vlen = btf_vlen(t);
 
 	switch (btf_kind(t)) {
 	case BTF_KIND_FWD:
@@ -506,7 +506,7 @@ static int btf_bswap_type_rest(struct btf_type *t)
 	struct btf_array *a;
 	struct btf_param *p;
 	struct btf_enum *e;
-	__u16 vlen = btf_vlen(t);
+	__u32 vlen = btf_vlen(t);
 	int i;
 
 	switch (btf_kind(t)) {
@@ -1007,7 +1007,7 @@ int btf__align_of(const struct btf *btf, __u32 id)
 	case BTF_KIND_STRUCT:
 	case BTF_KIND_UNION: {
 		const struct btf_member *m = btf_members(t);
-		__u16 vlen = btf_vlen(t);
+		__u32 vlen = btf_vlen(t);
 		int i, max_align = 1, align;
 
 		for (i = 0; i < vlen; i++, m++) {
@@ -2121,9 +2121,12 @@ static void *btf_add_type_mem(struct btf *btf, size_t add_sz)
 			      btf->hdr.type_len, UINT_MAX, add_sz);
 }
 
-static void btf_type_inc_vlen(struct btf_type *t)
+static int btf_type_inc_vlen(struct btf_type *t)
 {
+	if (btf_vlen(t) == BTF_MAX_VLEN)
+		return -ENOSPC;
 	t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, btf_kflag(t));
+	return 0;
 }
 
 static void btf_hdr_update_type_len(struct btf *btf, int new_len)
@@ -2652,6 +2655,8 @@ int btf__add_field(struct btf *btf, const char *name, int type_id,
 	t = btf_last_type(btf);
 	if (!btf_is_composite(t))
 		return libbpf_err(-EINVAL);
+	if (btf_vlen(t) == BTF_MAX_VLEN)
+		return libbpf_err(-ENOSPC);
 
 	if (validate_type_id(type_id))
 		return libbpf_err(-EINVAL);
@@ -2686,6 +2691,7 @@ int btf__add_field(struct btf *btf, const char *name, int type_id,
 
 	/* btf_add_type_mem can invalidate t pointer */
 	t = btf_last_type(btf);
+
 	/* update parent type's vlen and kflag */
 	t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, is_bitfield || btf_kflag(t));
 
@@ -2796,7 +2802,9 @@ int btf__add_enum_value(struct btf *btf, const char *name, __s64 value)
 
 	/* update parent type's vlen */
 	t = btf_last_type(btf);
-	btf_type_inc_vlen(t);
+	err = btf_type_inc_vlen(t);
+	if (err)
+		return libbpf_err(err);
 
 	/* if negative value, set signedness to signed */
 	if (value < 0)
@@ -2873,7 +2881,9 @@ int btf__add_enum64_value(struct btf *btf, const char *name, __u64 value)
 
 	/* update parent type's vlen */
 	t = btf_last_type(btf);
-	btf_type_inc_vlen(t);
+	err = btf_type_inc_vlen(t);
+	if (err)
+		return libbpf_err(err);
 
 	btf_hdr_update_type_len(btf, btf->hdr.type_len + sz);
 	return 0;
@@ -3115,7 +3125,9 @@ int btf__add_func_param(struct btf *btf, const char *name, int type_id)
 
 	/* update parent type's vlen */
 	t = btf_last_type(btf);
-	btf_type_inc_vlen(t);
+	err = btf_type_inc_vlen(t);
+	if (err)
+		return libbpf_err(err);
 
 	btf_hdr_update_type_len(btf, btf->hdr.type_len + sz);
 	return 0;
@@ -3257,7 +3269,9 @@ int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __
 
 	/* update parent type's vlen */
 	t = btf_last_type(btf);
-	btf_type_inc_vlen(t);
+	err = btf_type_inc_vlen(t);
+	if (err)
+		return libbpf_err(err);
 
 	btf_hdr_update_type_len(btf, btf->hdr.type_len + sz);
 	return 0;
@@ -4311,7 +4325,7 @@ static long btf_hash_enum(struct btf_type *t)
 static bool btf_equal_enum_members(struct btf_type *t1, struct btf_type *t2)
 {
 	const struct btf_enum *m1, *m2;
-	__u16 vlen;
+	__u32 vlen;
 	int i;
 
 	vlen = btf_vlen(t1);
@@ -4329,7 +4343,7 @@ static bool btf_equal_enum_members(struct btf_type *t1, struct btf_type *t2)
 static bool btf_equal_enum64_members(struct btf_type *t1, struct btf_type *t2)
 {
 	const struct btf_enum64 *m1, *m2;
-	__u16 vlen;
+	__u32 vlen;
 	int i;
 
 	vlen = btf_vlen(t1);
@@ -4406,7 +4420,7 @@ static long btf_hash_struct(struct btf_type *t)
 static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
 {
 	const struct btf_member *m1, *m2;
-	__u16 vlen;
+	__u32 vlen;
 	int i;
 
 	if (!btf_equal_common(t1, t2))
@@ -4482,7 +4496,7 @@ static bool btf_compat_array(struct btf_type *t1, struct btf_type *t2)
 static long btf_hash_fnproto(struct btf_type *t)
 {
 	const struct btf_param *member = btf_params(t);
-	__u16 vlen = btf_vlen(t);
+	__u32 vlen = btf_vlen(t);
 	long h = btf_hash_common(t);
 	int i;
 
@@ -4504,7 +4518,7 @@ static long btf_hash_fnproto(struct btf_type *t)
 static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
 {
 	const struct btf_param *m1, *m2;
-	__u16 vlen;
+	__u32 vlen;
 	int i;
 
 	if (!btf_equal_common(t1, t2))
@@ -4530,7 +4544,7 @@ static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
 static bool btf_compat_fnproto(struct btf_type *t1, struct btf_type *t2)
 {
 	const struct btf_param *m1, *m2;
-	__u16 vlen;
+	__u32 vlen;
 	int i;
 
 	/* skip return type ID */
@@ -5077,7 +5091,7 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
 	case BTF_KIND_STRUCT:
 	case BTF_KIND_UNION: {
 		const struct btf_member *cand_m, *canon_m;
-		__u16 vlen;
+		__u32 vlen;
 
 		if (!btf_shallow_equal_struct(cand_type, canon_type))
 			return 0;
@@ -5105,7 +5119,7 @@ static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
 
 	case BTF_KIND_FUNC_PROTO: {
 		const struct btf_param *cand_p, *canon_p;
-		__u16 vlen;
+		__u32 vlen;
 
 		if (!btf_compat_fnproto(cand_type, canon_type))
 			return 0;
@@ -5439,7 +5453,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
 
 	case BTF_KIND_FUNC_PROTO: {
 		struct btf_param *param;
-		__u16 vlen;
+		__u32 vlen;
 		int i;
 
 		ref_type_id = btf_dedup_ref_type(d, t->type);
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index a1f8deca2603..1a31f2da947f 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -435,7 +435,7 @@ static inline __u16 btf_kind(const struct btf_type *t)
 	return BTF_INFO_KIND(t->info);
 }
 
-static inline __u16 btf_vlen(const struct btf_type *t)
+static inline __u32 btf_vlen(const struct btf_type *t)
 {
 	return BTF_INFO_VLEN(t->info);
 }
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 53c6624161d7..cc1ba65bb6c5 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -316,7 +316,7 @@ static int btf_dump_mark_referenced(struct btf_dump *d)
 {
 	int i, j, n = btf__type_cnt(d->btf);
 	const struct btf_type *t;
-	__u16 vlen;
+	__u32 vlen;
 
 	for (i = d->last_id + 1; i < n; i++) {
 		t = btf__type_by_id(d->btf, i);
@@ -485,7 +485,7 @@ static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr)
 	 */
 	struct btf_dump_type_aux_state *tstate = &d->type_states[id];
 	const struct btf_type *t;
-	__u16 vlen;
+	__u32 vlen;
 	int err, i;
 
 	/* return true, letting typedefs know that it's ok to be emitted */
@@ -798,7 +798,7 @@ static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id)
 		 */
 		if (top_level_def || t->name_off == 0) {
 			const struct btf_member *m = btf_members(t);
-			__u16 vlen = btf_vlen(t);
+			__u32 vlen = btf_vlen(t);
 			int i, new_cont_id;
 
 			new_cont_id = t->name_off == 0 ? cont_id : id;
@@ -820,7 +820,7 @@ static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id)
 		break;
 	case BTF_KIND_FUNC_PROTO: {
 		const struct btf_param *p = btf_params(t);
-		__u16 n = btf_vlen(t);
+		__u32 n = btf_vlen(t);
 		int i;
 
 		btf_dump_emit_type(d, t->type, cont_id);
@@ -839,7 +839,7 @@ static bool btf_is_struct_packed(const struct btf *btf, __u32 id,
 {
 	const struct btf_member *m;
 	int max_align = 1, align, i, bit_sz;
-	__u16 vlen;
+	__u32 vlen;
 
 	m = btf_members(t);
 	vlen = btf_vlen(t);
@@ -973,7 +973,7 @@ static void btf_dump_emit_struct_def(struct btf_dump *d,
 	bool is_struct = btf_is_struct(t);
 	bool packed, prev_bitfield = false;
 	int align, i, off = 0;
-	__u16 vlen = btf_vlen(t);
+	__u32 vlen = btf_vlen(t);
 
 	align = btf__align_of(d->btf, id);
 	packed = is_struct ? btf_is_struct_packed(d->btf, id, t) : 0;
@@ -1064,7 +1064,7 @@ static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id,
 
 static void btf_dump_emit_enum32_val(struct btf_dump *d,
 				     const struct btf_type *t,
-				     int lvl, __u16 vlen)
+				     int lvl, __u32 vlen)
 {
 	const struct btf_enum *v = btf_enum(t);
 	bool is_signed = btf_kflag(t);
@@ -1089,7 +1089,7 @@ static void btf_dump_emit_enum32_val(struct btf_dump *d,
 
 static void btf_dump_emit_enum64_val(struct btf_dump *d,
 				     const struct btf_type *t,
-				     int lvl, __u16 vlen)
+				     int lvl, __u32 vlen)
 {
 	const struct btf_enum64 *v = btf_enum64(t);
 	bool is_signed = btf_kflag(t);
@@ -1122,7 +1122,7 @@ static void btf_dump_emit_enum_def(struct btf_dump *d, __u32 id,
 				   const struct btf_type *t,
 				   int lvl)
 {
-	__u16 vlen = btf_vlen(t);
+	__u32 vlen = btf_vlen(t);
 
 	btf_dump_printf(d, "enum%s%s",
 			t->name_off ? " " : "",
@@ -1542,7 +1542,7 @@ static void btf_dump_emit_type_chain(struct btf_dump *d,
 		}
 		case BTF_KIND_FUNC_PROTO: {
 			const struct btf_param *p = btf_params(t);
-			__u16 vlen = btf_vlen(t);
+			__u32 vlen = btf_vlen(t);
 			int i;
 
 			/*
@@ -2159,7 +2159,7 @@ static int btf_dump_struct_data(struct btf_dump *d,
 				const void *data)
 {
 	const struct btf_member *m = btf_members(t);
-	__u16 n = btf_vlen(t);
+	__u32 n = btf_vlen(t);
 	int i, err = 0;
 
 	/* note that we increment depth before calling btf_dump_print() below;
@@ -2449,7 +2449,7 @@ static int btf_dump_type_data_check_zero(struct btf_dump *d,
 	case BTF_KIND_STRUCT:
 	case BTF_KIND_UNION: {
 		const struct btf_member *m = btf_members(t);
-		__u16 n = btf_vlen(t);
+		__u32 n = btf_vlen(t);
 
 		/* if any struct/union member is non-zero, the struct/union
 		 * is considered non-zero and dumped.
diff --git a/tools/lib/bpf/relo_core.c b/tools/lib/bpf/relo_core.c
index 0ccc8f548cba..6ae3f2a15ad0 100644
--- a/tools/lib/bpf/relo_core.c
+++ b/tools/lib/bpf/relo_core.c
@@ -191,8 +191,8 @@ recur:
 	case BTF_KIND_FUNC_PROTO: {
 		struct btf_param *local_p = btf_params(local_type);
 		struct btf_param *targ_p = btf_params(targ_type);
-		__u16 local_vlen = btf_vlen(local_type);
-		__u16 targ_vlen = btf_vlen(targ_type);
+		__u32 local_vlen = btf_vlen(local_type);
+		__u32 targ_vlen = btf_vlen(targ_type);
 		int i, err;
 
 		if (local_vlen != targ_vlen)
@@ -1457,8 +1457,8 @@ static bool bpf_core_names_match(const struct btf *local_btf, size_t local_name_
 static int bpf_core_enums_match(const struct btf *local_btf, const struct btf_type *local_t,
 				const struct btf *targ_btf, const struct btf_type *targ_t)
 {
-	__u16 local_vlen = btf_vlen(local_t);
-	__u16 targ_vlen = btf_vlen(targ_t);
+	__u32 local_vlen = btf_vlen(local_t);
+	__u32 targ_vlen = btf_vlen(targ_t);
 	int i, j;
 
 	if (local_t->size != targ_t->size)
@@ -1498,8 +1498,8 @@ static int bpf_core_composites_match(const struct btf *local_btf, const struct b
 				     bool behind_ptr, int level)
 {
 	const struct btf_member *local_m = btf_members(local_t);
-	__u16 local_vlen = btf_vlen(local_t);
-	__u16 targ_vlen = btf_vlen(targ_t);
+	__u32 local_vlen = btf_vlen(local_t);
+	__u32 targ_vlen = btf_vlen(targ_t);
 	int i, j, err;
 
 	if (local_vlen > targ_vlen)
@@ -1674,8 +1674,8 @@ recur:
 	case BTF_KIND_FUNC_PROTO: {
 		struct btf_param *local_p = btf_params(local_t);
 		struct btf_param *targ_p = btf_params(targ_t);
-		__u16 local_vlen = btf_vlen(local_t);
-		__u16 targ_vlen = btf_vlen(targ_t);
+		__u32 local_vlen = btf_vlen(local_t);
+		__u32 targ_vlen = btf_vlen(targ_t);
 		int i, err;
 
 		if (local_k != targ_k)
diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c b/tools/testing/selftests/bpf/prog_tests/btf.c
index 054ecb6b1e9f..a9de328a8697 100644
--- a/tools/testing/selftests/bpf/prog_tests/btf.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf.c
@@ -1924,11 +1924,11 @@ static struct btf_raw_test raw_tests[] = {
 },
 
 {
-	.descr = "invalid BTF_INFO",
+	.descr = "invalid BTF kind",
 	.raw_types = {
 		/* int */				/* [1] */
 		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
-		BTF_TYPE_ENC(0, 0x20000000, 4),
+		BTF_TYPE_ENC(0, 0x7f000000, 4),
 		BTF_END_RAW,
 	},
 	.str_sec = "",
@@ -1941,7 +1941,7 @@ static struct btf_raw_test raw_tests[] = {
 	.value_type_id = 1,
 	.max_entries = 4,
 	.btf_load_err = true,
-	.err_str = "Invalid btf_info",
+	.err_str = "Invalid kind",
 },
 
 {
@@ -8092,7 +8092,7 @@ static struct btf_dedup_test dedup_tests[] = {
 static int btf_type_size(const struct btf_type *t)
 {
 	int base_size = sizeof(struct btf_type);
-	__u16 vlen = BTF_INFO_VLEN(t->info);
+	__u32 vlen = BTF_INFO_VLEN(t->info);
 	__u16 kind = BTF_INFO_KIND(t->info);
 
 	switch (kind) {
diff --git a/tools/testing/selftests/bpf/prog_tests/btf_dedup_split.c b/tools/testing/selftests/bpf/prog_tests/btf_dedup_split.c
index 5bc15bb6b7ce..6bc31236805c 100644
--- a/tools/testing/selftests/bpf/prog_tests/btf_dedup_split.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf_dedup_split.c
@@ -487,9 +487,8 @@ static void test_split_module(void)
 	for (i = 0; i < ARRAY_SIZE(mod_funcs); i++) {
 		const struct btf_param *p;
 		const struct btf_type *t;
-		__u16 vlen;
+		__u32 vlen, j;
 		__u32 id;
-		int j;
 
 		id = btf__find_by_name_kind(btf1, mod_funcs[i], BTF_KIND_FUNC);
 		if (!ASSERT_GE(id, nr_base_types, "func_id"))
diff --git a/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c b/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c
index 469e92869523..5064aeb8fe67 100644
--- a/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c
+++ b/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c
@@ -253,8 +253,7 @@ static int find_field_offset_aux(struct btf *btf, int btf_id, char *field_name,
 {
 	const struct btf_type *type = btf__type_by_id(btf, btf_id);
 	const struct btf_member *m;
-	__u16 mnum;
-	int i;
+	__u32 mnum, i;
 
 	if (!type) {
 		PRINT_FAIL("Can't find btf_type for id %d\n", btf_id);
diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index 7fe16b5131b1..cc14b13e23fe 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -1257,7 +1257,7 @@ int get_bpf_max_tramp_links_from(struct btf *btf)
 	const struct btf_type *t;
 	__u32 i, type_cnt;
 	const char *name;
-	__u16 j, vlen;
+	__u32 j, vlen;
 
 	for (i = 1, type_cnt = btf__type_cnt(btf); i < type_cnt; i++) {
 		t = btf__type_by_id(btf, i);