Merge branch 'Introduce type match support'

Daniel Müller says:

====================

This patch set proposes the addition of a new way for performing type queries to
BPF. It introduces the "type matches" relation, similar to what is already
present with "type exists" (in the form of bpf_core_type_exists).

"type exists" performs fairly superficial checking, mostly concerned with
whether a type exists in the kernel and is of the same kind (enum/struct/...).
Notably, compatibility checks for members of composite types is lacking.

The newly introduced "type matches" (bpf_core_type_matches) fills this gap in
that it performs stricter checks: compatibility of members and existence of
similarly named enum variants is checked as well. E.g., given these definitions:

	struct task_struct___og { int pid; int tgid; };

	struct task_struct___foo { int foo; }

'task_struct___og' would "match" the kernel type 'task_struct', because the
members match up, while 'task_struct___foo' would not match, because the
kernel's 'task_struct' has no member named 'foo'.

More precisely, the "type match" relation is defined as follows (copied from
source):
- modifiers and typedefs are stripped (and, hence, effectively ignored)
- generally speaking types need to be of same kind (struct vs. struct, union
  vs. union, etc.)
  - exceptions are struct/union behind a pointer which could also match a
    forward declaration of a struct or union, respectively, and enum vs.
    enum64 (see below)
Then, depending on type:
- integers:
  - match if size and signedness match
- arrays & pointers:
  - target types are recursively matched
- structs & unions:
  - local members need to exist in target with the same name
  - for each member we recursively check match unless it is already behind a
    pointer, in which case we only check matching names and compatible kind
- enums:
  - local variants have to have a match in target by symbolic name (but not
    numeric value)
  - size has to match (but enum may match enum64 and vice versa)
- function pointers:
  - number and position of arguments in local type has to match target
  - for each argument and the return value we recursively check match

Enabling this feature requires a new relocation to be made known to the
compiler. This is being taken care of for LLVM as part of
https://reviews.llvm.org/D126838.

If applied, among other things, usage of this functionality could have helped
flag issues such as the one discussed here
https://lore.kernel.org/all/93a20759600c05b6d9e4359a1517c88e06b44834.camel@fb.com/
earlier.

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
---
Changelog:
v2 -> v3:
- renamed btfgen_mark_types_match
- covered BTF_KIND_RESTRICT in type match marking logic
- used bpf_core_names_match in more places
- reworked "behind pointer" logic
- added test using live task_struct

v1 -> v2:
- deduplicated and moved core algorithm into relo_core.c
- adjusted bpf_core_names_match to get btf_type passed in
- removed some length equality checks before strncmp usage
- correctly use kflag from targ_t instead of local_t
- added comment for meaning of kflag w/ FWD kind
- __u32 -> u32
- handle BTF_KIND_FWD properly in bpftool marking logic
- rebased
====================

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>

13 files changed, 648 insertions, 18 deletions

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index ad9e7311c4cf..379e68fb866f 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -6786,6 +6786,7 @@ enum bpf_core_relo_kind {
 	BPF_CORE_TYPE_SIZE = 9,              /* type size in bytes */
 	BPF_CORE_ENUMVAL_EXISTS = 10,        /* enum value existence in target kernel */
 	BPF_CORE_ENUMVAL_VALUE = 11,         /* enum value integer value */
+	BPF_CORE_TYPE_MATCHES = 12,          /* type match in target kernel */
 };
 
 /*
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 8d3c7ab8af46..4f2408a4df08 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -7443,6 +7443,15 @@ int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
 					   MAX_TYPES_ARE_COMPAT_DEPTH);
 }
 
+#define MAX_TYPES_MATCH_DEPTH 2
+
+int bpf_core_types_match(const struct btf *local_btf, u32 local_id,
+			 const struct btf *targ_btf, u32 targ_id)
+{
+	return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false,
+				      MAX_TYPES_MATCH_DEPTH);
+}
+
 static bool bpf_core_is_flavor_sep(const char *s)
 {
 	/* check X___Y name pattern, where X and Y are not underscores */
diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index 480cbd859359..3d35fbc5fe16 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -1856,6 +1856,112 @@ static int btfgen_record_field_relo(struct btfgen_info *info, struct bpf_core_sp
 	return 0;
 }
 
+/* Mark types, members, and member types. Compared to btfgen_record_field_relo,
+ * this function does not rely on the target spec for inferring members, but
+ * uses the associated BTF.
+ *
+ * The `behind_ptr` argument is used to stop marking of composite types reached
+ * through a pointer. This way, we can keep BTF size in check while providing
+ * reasonable match semantics.
+ */
+static int btfgen_mark_type_match(struct btfgen_info *info, __u32 type_id, bool behind_ptr)
+{
+	const struct btf_type *btf_type;
+	struct btf *btf = info->src_btf;
+	struct btf_type *cloned_type;
+	int i, err;
+
+	if (type_id == 0)
+		return 0;
+
+	btf_type = btf__type_by_id(btf, type_id);
+	/* mark type on cloned BTF as used */
+	cloned_type = (struct btf_type *)btf__type_by_id(info->marked_btf, type_id);
+	cloned_type->name_off = MARKED;
+
+	switch (btf_kind(btf_type)) {
+	case BTF_KIND_UNKN:
+	case BTF_KIND_INT:
+	case BTF_KIND_FLOAT:
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+		break;
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION: {
+		struct btf_member *m = btf_members(btf_type);
+		__u16 vlen = btf_vlen(btf_type);
+
+		if (behind_ptr)
+			break;
+
+		for (i = 0; i < vlen; i++, m++) {
+			/* mark member */
+			btfgen_mark_member(info, type_id, i);
+
+			/* mark member's type */
+			err = btfgen_mark_type_match(info, m->type, false);
+			if (err)
+				return err;
+		}
+		break;
+	}
+	case BTF_KIND_CONST:
+	case BTF_KIND_FWD:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_VOLATILE:
+		return btfgen_mark_type_match(info, btf_type->type, behind_ptr);
+	case BTF_KIND_PTR:
+		return btfgen_mark_type_match(info, btf_type->type, true);
+	case BTF_KIND_ARRAY: {
+		struct btf_array *array;
+
+		array = btf_array(btf_type);
+		/* mark array type */
+		err = btfgen_mark_type_match(info, array->type, false);
+		/* mark array's index type */
+		err = err ? : btfgen_mark_type_match(info, array->index_type, false);
+		if (err)
+			return err;
+		break;
+	}
+	case BTF_KIND_FUNC_PROTO: {
+		__u16 vlen = btf_vlen(btf_type);
+		struct btf_param *param;
+
+		/* mark ret type */
+		err = btfgen_mark_type_match(info, btf_type->type, false);
+		if (err)
+			return err;
+
+		/* mark parameters types */
+		param = btf_params(btf_type);
+		for (i = 0; i < vlen; i++) {
+			err = btfgen_mark_type_match(info, param->type, false);
+			if (err)
+				return err;
+			param++;
+		}
+		break;
+	}
+	/* tells if some other type needs to be handled */
+	default:
+		p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* Mark types, members, and member types. Compared to btfgen_record_field_relo,
+ * this function does not rely on the target spec for inferring members, but
+ * uses the associated BTF.
+ */
+static int btfgen_record_type_match_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
+{
+	return btfgen_mark_type_match(info, targ_spec->root_type_id, false);
+}
+
 static int btfgen_record_type_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
 {
 	return btfgen_mark_type(info, targ_spec->root_type_id, true);
@@ -1882,6 +1988,8 @@ static int btfgen_record_reloc(struct btfgen_info *info, struct bpf_core_spec *r
 	case BPF_CORE_TYPE_EXISTS:
 	case BPF_CORE_TYPE_SIZE:
 		return btfgen_record_type_relo(info, res);
+	case BPF_CORE_TYPE_MATCHES:
+		return btfgen_record_type_match_relo(info, res);
 	case BPF_CORE_ENUMVAL_EXISTS:
 	case BPF_CORE_ENUMVAL_VALUE:
 		return btfgen_record_enumval_relo(info, res);
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index ad9e7311c4cf..379e68fb866f 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -6786,6 +6786,7 @@ enum bpf_core_relo_kind {
 	BPF_CORE_TYPE_SIZE = 9,              /* type size in bytes */
 	BPF_CORE_ENUMVAL_EXISTS = 10,        /* enum value existence in target kernel */
 	BPF_CORE_ENUMVAL_VALUE = 11,         /* enum value integer value */
+	BPF_CORE_TYPE_MATCHES = 12,          /* type match in target kernel */
 };
 
 /*
diff --git a/tools/lib/bpf/bpf_core_read.h b/tools/lib/bpf/bpf_core_read.h
index fd48b1ff59ca..496e6a8ee0dc 100644
--- a/tools/lib/bpf/bpf_core_read.h
+++ b/tools/lib/bpf/bpf_core_read.h
@@ -29,6 +29,7 @@ enum bpf_type_id_kind {
 enum bpf_type_info_kind {
 	BPF_TYPE_EXISTS = 0,		/* type existence in target kernel */
 	BPF_TYPE_SIZE = 1,		/* type size in target kernel */
+	BPF_TYPE_MATCHES = 2,		/* type match in target kernel */
 };
 
 /* second argument to __builtin_preserve_enum_value() built-in */
@@ -184,6 +185,16 @@ enum bpf_enum_value_kind {
 	__builtin_preserve_type_info(*(typeof(type) *)0, BPF_TYPE_EXISTS)
 
 /*
+ * Convenience macro to check that provided named type
+ * (struct/union/enum/typedef) "matches" that in a target kernel.
+ * Returns:
+ *    1, if the type matches in the target kernel's BTF;
+ *    0, if the type does not match any in the target kernel
+ */
+#define bpf_core_type_matches(type)					    \
+	__builtin_preserve_type_info(*(typeof(type) *)0, BPF_TYPE_MATCHES)
+
+/*
  * Convenience macro to get the byte size of a provided named type
  * (struct/union/enum/typedef) in a target kernel.
  * Returns:
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 8a45a84eb9b2..64c4cc6140d3 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -5470,6 +5470,12 @@ int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
 	return __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id, 32);
 }
 
+int bpf_core_types_match(const struct btf *local_btf, __u32 local_id,
+			 const struct btf *targ_btf, __u32 targ_id)
+{
+	return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false, 32);
+}
+
 static size_t bpf_core_hash_fn(const void *key, void *ctx)
 {
 	return (size_t)key;
diff --git a/tools/lib/bpf/relo_core.c b/tools/lib/bpf/relo_core.c
index e070123332cd..fe2533022aa9 100644
--- a/tools/lib/bpf/relo_core.c
+++ b/tools/lib/bpf/relo_core.c
@@ -95,6 +95,7 @@ static const char *core_relo_kind_str(enum bpf_core_relo_kind kind)
 	case BPF_CORE_TYPE_ID_LOCAL: return "local_type_id";
 	case BPF_CORE_TYPE_ID_TARGET: return "target_type_id";
 	case BPF_CORE_TYPE_EXISTS: return "type_exists";
+	case BPF_CORE_TYPE_MATCHES: return "type_matches";
 	case BPF_CORE_TYPE_SIZE: return "type_size";
 	case BPF_CORE_ENUMVAL_EXISTS: return "enumval_exists";
 	case BPF_CORE_ENUMVAL_VALUE: return "enumval_value";
@@ -123,6 +124,7 @@ static bool core_relo_is_type_based(enum bpf_core_relo_kind kind)
 	case BPF_CORE_TYPE_ID_LOCAL:
 	case BPF_CORE_TYPE_ID_TARGET:
 	case BPF_CORE_TYPE_EXISTS:
+	case BPF_CORE_TYPE_MATCHES:
 	case BPF_CORE_TYPE_SIZE:
 		return true;
 	default:
@@ -251,7 +253,7 @@ recur:
  *   - field 'a' access (corresponds to '2' in low-level spec);
  *   - array element #3 access (corresponds to '3' in low-level spec).
  *
- * Type-based relocations (TYPE_EXISTS/TYPE_SIZE,
+ * Type-based relocations (TYPE_EXISTS/TYPE_MATCHES/TYPE_SIZE,
  * TYPE_ID_LOCAL/TYPE_ID_TARGET) don't capture any field information. Their
  * spec and raw_spec are kept empty.
  *
@@ -568,9 +570,14 @@ static int bpf_core_spec_match(struct bpf_core_spec *local_spec,
 	targ_spec->relo_kind = local_spec->relo_kind;
 
 	if (core_relo_is_type_based(local_spec->relo_kind)) {
-		return bpf_core_types_are_compat(local_spec->btf,
-						 local_spec->root_type_id,
-						 targ_btf, targ_id);
+		if (local_spec->relo_kind == BPF_CORE_TYPE_MATCHES)
+			return bpf_core_types_match(local_spec->btf,
+						    local_spec->root_type_id,
+						    targ_btf, targ_id);
+		else
+			return bpf_core_types_are_compat(local_spec->btf,
+							 local_spec->root_type_id,
+							 targ_btf, targ_id);
 	}
 
 	local_acc = &local_spec->spec[0];
@@ -819,6 +826,7 @@ static int bpf_core_calc_type_relo(const struct bpf_core_relo *relo,
 			*validate = false;
 		break;
 	case BPF_CORE_TYPE_EXISTS:
+	case BPF_CORE_TYPE_MATCHES:
 		*val = 1;
 		break;
 	case BPF_CORE_TYPE_SIZE:
@@ -1410,3 +1418,266 @@ int bpf_core_calc_relo_insn(const char *prog_name,
 
 	return 0;
 }
+
+static bool bpf_core_names_match(const struct btf *local_btf, size_t local_name_off,
+				 const struct btf *targ_btf, size_t targ_name_off)
+{
+	const char *local_n, *targ_n;
+	size_t local_len, targ_len;
+
+	local_n = btf__name_by_offset(local_btf, local_name_off);
+	targ_n = btf__name_by_offset(targ_btf, targ_name_off);
+
+	if (str_is_empty(targ_n))
+		return str_is_empty(local_n);
+
+	targ_len = bpf_core_essential_name_len(targ_n);
+	local_len = bpf_core_essential_name_len(local_n);
+
+	return targ_len == local_len && strncmp(local_n, targ_n, local_len) == 0;
+}
+
+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);
+	int i, j;
+
+	if (local_t->size != targ_t->size)
+		return 0;
+
+	if (local_vlen > targ_vlen)
+		return 0;
+
+	/* iterate over the local enum's variants and make sure each has
+	 * a symbolic name correspondent in the target
+	 */
+	for (i = 0; i < local_vlen; i++) {
+		bool matched = false;
+		__u32 local_n_off, targ_n_off;
+
+		local_n_off = btf_is_enum(local_t) ? btf_enum(local_t)[i].name_off :
+						     btf_enum64(local_t)[i].name_off;
+
+		for (j = 0; j < targ_vlen; j++) {
+			targ_n_off = btf_is_enum(targ_t) ? btf_enum(targ_t)[j].name_off :
+							   btf_enum64(targ_t)[j].name_off;
+
+			if (bpf_core_names_match(local_btf, local_n_off, targ_btf, targ_n_off)) {
+				matched = true;
+				break;
+			}
+		}
+
+		if (!matched)
+			return 0;
+	}
+	return 1;
+}
+
+static int bpf_core_composites_match(const struct btf *local_btf, const struct btf_type *local_t,
+				     const struct btf *targ_btf, const struct btf_type *targ_t,
+				     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);
+	int i, j, err;
+
+	if (local_vlen > targ_vlen)
+		return 0;
+
+	/* check that all local members have a match in the target */
+	for (i = 0; i < local_vlen; i++, local_m++) {
+		const struct btf_member *targ_m = btf_members(targ_t);
+		bool matched = false;
+
+		for (j = 0; j < targ_vlen; j++, targ_m++) {
+			if (!bpf_core_names_match(local_btf, local_m->name_off,
+						  targ_btf, targ_m->name_off))
+				continue;
+
+			err = __bpf_core_types_match(local_btf, local_m->type, targ_btf,
+						     targ_m->type, behind_ptr, level - 1);
+			if (err > 0) {
+				matched = true;
+				break;
+			}
+		}
+
+		if (!matched)
+			return 0;
+	}
+	return 1;
+}
+
+/* Check that two types "match".
+ *
+ * The matching relation is defined as follows:
+ * - modifiers and typedefs are stripped (and, hence, effectively ignored)
+ * - generally speaking types need to be of same kind (struct vs. struct, union
+ *   vs. union, etc.)
+ *   - exceptions are struct/union behind a pointer which could also match a
+ *     forward declaration of a struct or union, respectively, and enum vs.
+ *     enum64 (see below)
+ * Then, depending on type:
+ * - integers:
+ *   - match if size and signedness match
+ * - arrays & pointers:
+ *   - target types are recursively matched
+ * - structs & unions:
+ *   - local members need to exist in target with the same name
+ *   - for each member we recursively check match unless it is already behind a
+ *     pointer, in which case we only check matching names and compatible kind
+ * - enums:
+ *   - local variants have to have a match in target by symbolic name (but not
+ *     numeric value)
+ *   - size has to match (but enum may match enum64 and vice versa)
+ * - function pointers:
+ *   - number and position of arguments in local type has to match target
+ *   - for each argument and the return value we recursively check match
+ */
+int __bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
+			   __u32 targ_id, bool behind_ptr, int level)
+{
+	const struct btf_type *local_t, *targ_t;
+	int depth = 32; /* max recursion depth */
+	__u16 local_k, targ_k;
+
+	if (level <= 0)
+		return -EINVAL;
+
+	local_t = btf_type_by_id(local_btf, local_id);
+	targ_t = btf_type_by_id(targ_btf, targ_id);
+
+recur:
+	depth--;
+	if (depth < 0)
+		return -EINVAL;
+
+	local_t = skip_mods_and_typedefs(local_btf, local_id, &local_id);
+	targ_t = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
+	if (!local_t || !targ_t)
+		return -EINVAL;
+
+	if (!bpf_core_names_match(local_btf, local_t->name_off, targ_btf, targ_t->name_off))
+		return 0;
+
+	local_k = btf_kind(local_t);
+	targ_k = btf_kind(targ_t);
+
+	switch (local_k) {
+	case BTF_KIND_UNKN:
+		return local_k == targ_k;
+	case BTF_KIND_FWD: {
+		bool local_f = BTF_INFO_KFLAG(local_t->info);
+
+		if (behind_ptr) {
+			if (local_k == targ_k)
+				return local_f == BTF_INFO_KFLAG(targ_t->info);
+
+			/* for forward declarations kflag dictates whether the
+			 * target is a struct (0) or union (1)
+			 */
+			return (targ_k == BTF_KIND_STRUCT && !local_f) ||
+			       (targ_k == BTF_KIND_UNION && local_f);
+		} else {
+			if (local_k != targ_k)
+				return 0;
+
+			/* match if the forward declaration is for the same kind */
+			return local_f == BTF_INFO_KFLAG(targ_t->info);
+		}
+	}
+	case BTF_KIND_ENUM:
+	case BTF_KIND_ENUM64:
+		if (!btf_is_any_enum(targ_t))
+			return 0;
+
+		return bpf_core_enums_match(local_btf, local_t, targ_btf, targ_t);
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+		if (behind_ptr) {
+			bool targ_f = BTF_INFO_KFLAG(targ_t->info);
+
+			if (local_k == targ_k)
+				return 1;
+
+			if (targ_k != BTF_KIND_FWD)
+				return 0;
+
+			return (local_k == BTF_KIND_UNION) == targ_f;
+		} else {
+			if (local_k != targ_k)
+				return 0;
+
+			return bpf_core_composites_match(local_btf, local_t, targ_btf, targ_t,
+							 behind_ptr, level);
+		}
+	case BTF_KIND_INT: {
+		__u8 local_sgn;
+		__u8 targ_sgn;
+
+		if (local_k != targ_k)
+			return 0;
+
+		local_sgn = btf_int_encoding(local_t) & BTF_INT_SIGNED;
+		targ_sgn = btf_int_encoding(targ_t) & BTF_INT_SIGNED;
+
+		return local_t->size == targ_t->size && local_sgn == targ_sgn;
+	}
+	case BTF_KIND_PTR:
+		if (local_k != targ_k)
+			return 0;
+
+		behind_ptr = true;
+
+		local_id = local_t->type;
+		targ_id = targ_t->type;
+		goto recur;
+	case BTF_KIND_ARRAY: {
+		const struct btf_array *local_array = btf_array(local_t);
+		const struct btf_array *targ_array = btf_array(targ_t);
+
+		if (local_k != targ_k)
+			return 0;
+
+		if (local_array->nelems != targ_array->nelems)
+			return 0;
+
+		local_id = local_array->type;
+		targ_id = targ_array->type;
+		goto 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);
+		int i, err;
+
+		if (local_k != targ_k)
+			return 0;
+
+		if (local_vlen != targ_vlen)
+			return 0;
+
+		for (i = 0; i < local_vlen; i++, local_p++, targ_p++) {
+			err = __bpf_core_types_match(local_btf, local_p->type, targ_btf,
+						     targ_p->type, behind_ptr, level - 1);
+			if (err <= 0)
+				return err;
+		}
+
+		/* tail recurse for return type check */
+		local_id = local_t->type;
+		targ_id = targ_t->type;
+		goto recur;
+	}
+	default:
+		pr_warn("unexpected kind %s relocated, local [%d], target [%d]\n",
+			btf_kind_str(local_t), local_id, targ_id);
+		return 0;
+	}
+}
diff --git a/tools/lib/bpf/relo_core.h b/tools/lib/bpf/relo_core.h
index 3fd3842d4230..1c0566daf8e8 100644
--- a/tools/lib/bpf/relo_core.h
+++ b/tools/lib/bpf/relo_core.h
@@ -72,6 +72,10 @@ int __bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
 				const struct btf *targ_btf, __u32 targ_id, int level);
 int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
 			      const struct btf *targ_btf, __u32 targ_id);
+int __bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
+			   __u32 targ_id, bool behind_ptr, int level);
+int bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
+			 __u32 targ_id);
 
 size_t bpf_core_essential_name_len(const char *name);
 
diff --git a/tools/testing/selftests/bpf/prog_tests/core_reloc.c b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
index 2f92feb809be..a6f65e2236f4 100644
--- a/tools/testing/selftests/bpf/prog_tests/core_reloc.c
+++ b/tools/testing/selftests/bpf/prog_tests/core_reloc.c
@@ -543,7 +543,6 @@ static int __trigger_module_test_read(const struct core_reloc_test_case *test)
 	return 0;
 }
 
-
 static const struct core_reloc_test_case test_cases[] = {
 	/* validate we can find kernel image and use its BTF for relocs */
 	{
@@ -556,6 +555,7 @@ static const struct core_reloc_test_case test_cases[] = {
 			.valid = { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, },
 			.comm = "test_progs",
 			.comm_len = sizeof("test_progs"),
+			.local_task_struct_matches = true,
 		},
 		.output_len = sizeof(struct core_reloc_kernel_output),
 		.raw_tp_name = "sys_enter",
@@ -752,9 +752,10 @@ static const struct core_reloc_test_case test_cases[] = {
 	SIZE_CASE(size___diff_offs),
 	SIZE_ERR_CASE(size___err_ambiguous),
 
-	/* validate type existence and size relocations */
+	/* validate type existence, match, and size relocations */
 	TYPE_BASED_CASE(type_based, {
 		.struct_exists = 1,
+		.complex_struct_exists = 1,
 		.union_exists = 1,
 		.enum_exists = 1,
 		.typedef_named_struct_exists = 1,
@@ -765,6 +766,20 @@ static const struct core_reloc_test_case test_cases[] = {
 		.typedef_void_ptr_exists = 1,
 		.typedef_func_proto_exists = 1,
 		.typedef_arr_exists = 1,
+
+		.struct_matches = 1,
+		.complex_struct_matches = 1,
+		.union_matches = 1,
+		.enum_matches = 1,
+		.typedef_named_struct_matches = 1,
+		.typedef_anon_struct_matches = 1,
+		.typedef_struct_ptr_matches = 1,
+		.typedef_int_matches = 1,
+		.typedef_enum_matches = 1,
+		.typedef_void_ptr_matches = 1,
+		.typedef_func_proto_matches = 1,
+		.typedef_arr_matches = 1,
+
 		.struct_sz = sizeof(struct a_struct),
 		.union_sz = sizeof(union a_union),
 		.enum_sz = sizeof(enum an_enum),
@@ -780,6 +795,45 @@ static const struct core_reloc_test_case test_cases[] = {
 	TYPE_BASED_CASE(type_based___all_missing, {
 		/* all zeros */
 	}),
+	TYPE_BASED_CASE(type_based___diff, {
+		.struct_exists = 1,
+		.complex_struct_exists = 1,
+		.union_exists = 1,
+		.enum_exists = 1,
+		.typedef_named_struct_exists = 1,
+		.typedef_anon_struct_exists = 1,
+		.typedef_struct_ptr_exists = 1,
+		.typedef_int_exists = 1,
+		.typedef_enum_exists = 1,
+		.typedef_void_ptr_exists = 1,
+		.typedef_func_proto_exists = 1,
+		.typedef_arr_exists = 1,
+
+		.struct_matches = 1,
+		.complex_struct_matches = 1,
+		.union_matches = 1,
+		.enum_matches = 1,
+		.typedef_named_struct_matches = 1,
+		.typedef_anon_struct_matches = 1,
+		.typedef_struct_ptr_matches = 1,
+		.typedef_int_matches = 0,
+		.typedef_enum_matches = 1,
+		.typedef_void_ptr_matches = 1,
+		.typedef_func_proto_matches = 0,
+		.typedef_arr_matches = 0,
+
+		.struct_sz = sizeof(struct a_struct___diff),
+		.union_sz = sizeof(union a_union___diff),
+		.enum_sz = sizeof(enum an_enum___diff),
+		.typedef_named_struct_sz = sizeof(named_struct_typedef___diff),
+		.typedef_anon_struct_sz = sizeof(anon_struct_typedef___diff),
+		.typedef_struct_ptr_sz = sizeof(struct_ptr_typedef___diff),
+		.typedef_int_sz = sizeof(int_typedef___diff),
+		.typedef_enum_sz = sizeof(enum_typedef___diff),
+		.typedef_void_ptr_sz = sizeof(void_ptr_typedef___diff),
+		.typedef_func_proto_sz = sizeof(func_proto_typedef___diff),
+		.typedef_arr_sz = sizeof(arr_typedef___diff),
+	}),
 	TYPE_BASED_CASE(type_based___diff_sz, {
 		.struct_exists = 1,
 		.union_exists = 1,
@@ -792,6 +846,19 @@ static const struct core_reloc_test_case test_cases[] = {
 		.typedef_void_ptr_exists = 1,
 		.typedef_func_proto_exists = 1,
 		.typedef_arr_exists = 1,
+
+		.struct_matches = 0,
+		.union_matches = 0,
+		.enum_matches = 0,
+		.typedef_named_struct_matches = 0,
+		.typedef_anon_struct_matches = 0,
+		.typedef_struct_ptr_matches = 1,
+		.typedef_int_matches = 0,
+		.typedef_enum_matches = 0,
+		.typedef_void_ptr_matches = 1,
+		.typedef_func_proto_matches = 0,
+		.typedef_arr_matches = 0,
+
 		.struct_sz = sizeof(struct a_struct___diff_sz),
 		.union_sz = sizeof(union a_union___diff_sz),
 		.enum_sz = sizeof(enum an_enum___diff_sz),
@@ -806,10 +873,12 @@ static const struct core_reloc_test_case test_cases[] = {
 	}),
 	TYPE_BASED_CASE(type_based___incompat, {
 		.enum_exists = 1,
+		.enum_matches = 1,
 		.enum_sz = sizeof(enum an_enum),
 	}),
 	TYPE_BASED_CASE(type_based___fn_wrong_args, {
 		.struct_exists = 1,
+		.struct_matches = 1,
 		.struct_sz = sizeof(struct a_struct),
 	}),
 
diff --git a/tools/testing/selftests/bpf/progs/btf__core_reloc_type_based___diff.c b/tools/testing/selftests/bpf/progs/btf__core_reloc_type_based___diff.c
new file mode 100644
index 000000000000..57ae2c258928
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/btf__core_reloc_type_based___diff.c
@@ -0,0 +1,3 @@
+#include "core_reloc_types.h"
+
+void f(struct core_reloc_type_based___diff x) {}
diff --git a/tools/testing/selftests/bpf/progs/core_reloc_types.h b/tools/testing/selftests/bpf/progs/core_reloc_types.h
index 26e103302c05..7ef91d19c66e 100644
--- a/tools/testing/selftests/bpf/progs/core_reloc_types.h
+++ b/tools/testing/selftests/bpf/progs/core_reloc_types.h
@@ -13,6 +13,7 @@ struct core_reloc_kernel_output {
 	int valid[10];
 	char comm[sizeof("test_progs")];
 	int comm_len;
+	bool local_task_struct_matches;
 };
 
 /*
@@ -860,10 +861,11 @@ struct core_reloc_size___err_ambiguous2 {
 };
 
 /*
- * TYPE EXISTENCE & SIZE
+ * TYPE EXISTENCE, MATCH & SIZE
  */
 struct core_reloc_type_based_output {
 	bool struct_exists;
+	bool complex_struct_exists;
 	bool union_exists;
 	bool enum_exists;
 	bool typedef_named_struct_exists;
@@ -875,6 +877,19 @@ struct core_reloc_type_based_output {
 	bool typedef_func_proto_exists;
 	bool typedef_arr_exists;
 
+	bool struct_matches;
+	bool complex_struct_matches;
+	bool union_matches;
+	bool enum_matches;
+	bool typedef_named_struct_matches;
+	bool typedef_anon_struct_matches;
+	bool typedef_struct_ptr_matches;
+	bool typedef_int_matches;
+	bool typedef_enum_matches;
+	bool typedef_void_ptr_matches;
+	bool typedef_func_proto_matches;
+	bool typedef_arr_matches;
+
 	int struct_sz;
 	int union_sz;
 	int enum_sz;
@@ -892,6 +907,14 @@ struct a_struct {
 	int x;
 };
 
+struct a_complex_struct {
+	union {
+		struct a_struct * restrict a;
+		void *b;
+	} x;
+	volatile long y;
+};
+
 union a_union {
 	int y;
 	int z;
@@ -923,22 +946,85 @@ typedef char arr_typedef[20];
 
 struct core_reloc_type_based {
 	struct a_struct f1;
-	union a_union f2;
-	enum an_enum f3;
-	named_struct_typedef f4;
-	anon_struct_typedef f5;
-	struct_ptr_typedef f6;
-	int_typedef f7;
-	enum_typedef f8;
-	void_ptr_typedef f9;
-	func_proto_typedef f10;
-	arr_typedef f11;
+	struct a_complex_struct f2;
+	union a_union f3;
+	enum an_enum f4;
+	named_struct_typedef f5;
+	anon_struct_typedef f6;
+	struct_ptr_typedef f7;
+	int_typedef f8;
+	enum_typedef f9;
+	void_ptr_typedef f10;
+	func_proto_typedef f11;
+	arr_typedef f12;
 };
 
 /* no types in target */
 struct core_reloc_type_based___all_missing {
 };
 
+/* different member orders, enum variant values, signedness, etc */
+struct a_struct___diff {
+	int x;
+	int a;
+};
+
+struct a_struct___forward;
+
+struct a_complex_struct___diff {
+	union {
+		struct a_struct___forward *a;
+		void *b;
+	} x;
+	volatile long y;
+};
+
+union a_union___diff {
+	int z;
+	int y;
+};
+
+typedef struct a_struct___diff named_struct_typedef___diff;
+
+typedef struct { int z, x, y; } anon_struct_typedef___diff;
+
+typedef struct {
+	int c;
+	int b;
+	int a;
+} *struct_ptr_typedef___diff;
+
+enum an_enum___diff {
+	AN_ENUM_VAL2___diff = 0,
+	AN_ENUM_VAL1___diff = 42,
+	AN_ENUM_VAL3___diff = 1,
+};
+
+typedef unsigned int int_typedef___diff;
+
+typedef enum { TYPEDEF_ENUM_VAL2___diff, TYPEDEF_ENUM_VAL1___diff = 50 } enum_typedef___diff;
+
+typedef const void *void_ptr_typedef___diff;
+
+typedef int_typedef___diff (*func_proto_typedef___diff)(long);
+
+typedef char arr_typedef___diff[3];
+
+struct core_reloc_type_based___diff {
+	struct a_struct___diff f1;
+	struct a_complex_struct___diff f2;
+	union a_union___diff f3;
+	enum an_enum___diff f4;
+	named_struct_typedef___diff f5;
+	anon_struct_typedef___diff f6;
+	struct_ptr_typedef___diff f7;
+	int_typedef___diff f8;
+	enum_typedef___diff f9;
+	void_ptr_typedef___diff f10;
+	func_proto_typedef___diff f11;
+	arr_typedef___diff f12;
+};
+
 /* different type sizes, extra modifiers, anon vs named enums, etc */
 struct a_struct___diff_sz {
 	long x;
diff --git a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
index 145028b52ad8..a17dd83eae67 100644
--- a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
+++ b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
@@ -21,6 +21,7 @@ struct core_reloc_kernel_output {
 	/* we have test_progs[-flavor], so cut flavor part */
 	char comm[sizeof("test_progs")];
 	int comm_len;
+	bool local_task_struct_matches;
 };
 
 struct task_struct {
@@ -30,11 +31,25 @@ struct task_struct {
 	struct task_struct *group_leader;
 };
 
+struct mm_struct___wrong {
+    int abc_whatever_should_not_exist;
+};
+
+struct task_struct___local {
+    int pid;
+    struct mm_struct___wrong *mm;
+};
+
 #define CORE_READ(dst, src) bpf_core_read(dst, sizeof(*(dst)), src)
 
 SEC("raw_tracepoint/sys_enter")
 int test_core_kernel(void *ctx)
 {
+	/* Support for the BPF_TYPE_MATCHES argument to the
+	 * __builtin_preserve_type_info builtin was added at some point during
+	 * development of clang 15 and it's what we require for this test.
+	 */
+#if __has_builtin(__builtin_preserve_type_info) && __clang_major__ >= 15
 	struct task_struct *task = (void *)bpf_get_current_task();
 	struct core_reloc_kernel_output *out = (void *)&data.out;
 	uint64_t pid_tgid = bpf_get_current_pid_tgid();
@@ -93,6 +108,10 @@ int test_core_kernel(void *ctx)
 		group_leader, group_leader, group_leader, group_leader,
 		comm);
 
+	out->local_task_struct_matches = bpf_core_type_matches(struct task_struct___local);
+#else
+	data.skip = true;
+#endif
 	return 0;
 }
 
diff --git a/tools/testing/selftests/bpf/progs/test_core_reloc_type_based.c b/tools/testing/selftests/bpf/progs/test_core_reloc_type_based.c
index fb60f8195c53..d95bc08b75c1 100644
--- a/tools/testing/selftests/bpf/progs/test_core_reloc_type_based.c
+++ b/tools/testing/selftests/bpf/progs/test_core_reloc_type_based.c
@@ -19,6 +19,14 @@ struct a_struct {
 	int x;
 };
 
+struct a_complex_struct {
+	union {
+		struct a_struct *a;
+		void *b;
+	} x;
+	volatile long y;
+};
+
 union a_union {
 	int y;
 	int z;
@@ -50,6 +58,7 @@ typedef char arr_typedef[20];
 
 struct core_reloc_type_based_output {
 	bool struct_exists;
+	bool complex_struct_exists;
 	bool union_exists;
 	bool enum_exists;
 	bool typedef_named_struct_exists;
@@ -61,6 +70,19 @@ struct core_reloc_type_based_output {
 	bool typedef_func_proto_exists;
 	bool typedef_arr_exists;
 
+	bool struct_matches;
+	bool complex_struct_matches;
+	bool union_matches;
+	bool enum_matches;
+	bool typedef_named_struct_matches;
+	bool typedef_anon_struct_matches;
+	bool typedef_struct_ptr_matches;
+	bool typedef_int_matches;
+	bool typedef_enum_matches;
+	bool typedef_void_ptr_matches;
+	bool typedef_func_proto_matches;
+	bool typedef_arr_matches;
+
 	int struct_sz;
 	int union_sz;
 	int enum_sz;
@@ -77,10 +99,17 @@ struct core_reloc_type_based_output {
 SEC("raw_tracepoint/sys_enter")
 int test_core_type_based(void *ctx)
 {
-#if __has_builtin(__builtin_preserve_type_info)
+	/* Support for the BPF_TYPE_MATCHES argument to the
+	 * __builtin_preserve_type_info builtin was added at some point during
+	 * development of clang 15 and it's what we require for this test. Part of it
+	 * could run with merely __builtin_preserve_type_info (which could be checked
+	 * separately), but we have to find an upper bound.
+	 */
+#if __has_builtin(__builtin_preserve_type_info) && __clang_major__ >= 15
 	struct core_reloc_type_based_output *out = (void *)&data.out;
 
 	out->struct_exists = bpf_core_type_exists(struct a_struct);
+	out->complex_struct_exists = bpf_core_type_exists(struct a_complex_struct);
 	out->union_exists = bpf_core_type_exists(union a_union);
 	out->enum_exists = bpf_core_type_exists(enum an_enum);
 	out->typedef_named_struct_exists = bpf_core_type_exists(named_struct_typedef);
@@ -92,6 +121,19 @@ int test_core_type_based(void *ctx)
 	out->typedef_func_proto_exists = bpf_core_type_exists(func_proto_typedef);
 	out->typedef_arr_exists = bpf_core_type_exists(arr_typedef);
 
+	out->struct_matches = bpf_core_type_matches(struct a_struct);
+	out->complex_struct_matches = bpf_core_type_matches(struct a_complex_struct);
+	out->union_matches = bpf_core_type_matches(union a_union);
+	out->enum_matches = bpf_core_type_matches(enum an_enum);
+	out->typedef_named_struct_matches = bpf_core_type_matches(named_struct_typedef);
+	out->typedef_anon_struct_matches = bpf_core_type_matches(anon_struct_typedef);
+	out->typedef_struct_ptr_matches = bpf_core_type_matches(struct_ptr_typedef);
+	out->typedef_int_matches = bpf_core_type_matches(int_typedef);
+	out->typedef_enum_matches = bpf_core_type_matches(enum_typedef);
+	out->typedef_void_ptr_matches = bpf_core_type_matches(void_ptr_typedef);
+	out->typedef_func_proto_matches = bpf_core_type_matches(func_proto_typedef);
+	out->typedef_arr_matches = bpf_core_type_matches(arr_typedef);
+
 	out->struct_sz = bpf_core_type_size(struct a_struct);
 	out->union_sz = bpf_core_type_size(union a_union);
 	out->enum_sz = bpf_core_type_size(enum an_enum);