Merge branch 'bpf-type-format'

Martin KaFai Lau says:

====================
This patch introduces BPF Type Format (BTF).

BTF (BPF Type Format) is the meta data format which describes
the data types of BPF program/map.  Hence, it basically focus
on the C programming language which the modern BPF is primary
using.  The first use case is to provide a generic pretty print
capability for a BPF map.

A modified pahole that can convert dwarf to BTF is here:

  https://github.com/iamkafai/pahole/tree/btf

Please see individual patch for details.

v5:
- Remove BTF_KIND_FLOAT and BTF_KIND_FUNC which are not
  currently used.  They can be added in the future.
  Some bpf_df_xxx() are removed together.
- Add comment in patch 7 to clarify that the new bpffs_map_fops
  should not be extended further.

v4:
- Fix warning (remove unneeded semicolon)
- Remove a redundant variable (nr_bytes) from btf_int_check_meta() in
  patch 1.  Caught by W=1.

v3:
- Rebase to bpf-next
- Fix sparse warning (by adding static)
- Add BTF header logging: btf_verifier_log_hdr()
- Fix the alignment test on btf->type_off
- Add tests for the BTF header
- Lower the max BTF size to 16MB.  It should be enough
  for some time.  We could raise it later if it would
  be needed.

v2:
- Use kvfree where needed in patch 1 and 2
- Also consider BTF_INT_OFFSET() in the btf_int_check_meta()
  in patch 1
- Fix an incorrect goto target in map_create() during
  the btf-error-path in patch 7
- re-org some local vars to keep the rev xmas tree in btf.c
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

include/linux/bpf.h

@@ -22,6 +22,8 @@ struct perf_event;
 struct bpf_prog;
 struct bpf_map;
 struct sock;
+struct seq_file;
+struct btf;
 
 /* map is generic key/value storage optionally accesible by eBPF programs */
 struct bpf_map_ops {
@@ -43,10 +45,14 @@ struct bpf_map_ops {
 	void (*map_fd_put_ptr)(void *ptr);
 	u32 (*map_gen_lookup)(struct bpf_map *map, struct bpf_insn *insn_buf);
 	u32 (*map_fd_sys_lookup_elem)(void *ptr);
+	void (*map_seq_show_elem)(struct bpf_map *map, void *key,
+				  struct seq_file *m);
+	int (*map_check_btf)(const struct bpf_map *map, const struct btf *btf,
+			     u32 key_type_id, u32 value_type_id);
 };
 
 struct bpf_map {
-	/* 1st cacheline with read-mostly members of which some
+	/* The first two cachelines with read-mostly members of which some
 	 * are also accessed in fast-path (e.g. ops, max_entries).
 	 */
 	const struct bpf_map_ops *ops ____cacheline_aligned;
@@ -62,10 +68,13 @@ struct bpf_map {
 	u32 pages;
 	u32 id;
 	int numa_node;
+	u32 btf_key_id;
+	u32 btf_value_id;
+	struct btf *btf;
 	bool unpriv_array;
-	/* 7 bytes hole */
+	/* 55 bytes hole */
 
-	/* 2nd cacheline with misc members to avoid false sharing
+	/* The 3rd and 4th cacheline with misc members to avoid false sharing
 	 * particularly with refcounting.
 	 */
 	struct user_struct *user ____cacheline_aligned;
@@ -100,6 +109,11 @@ static inline struct bpf_offloaded_map *map_to_offmap(struct bpf_map *map)
 	return container_of(map, struct bpf_offloaded_map, map);
 }
 
+static inline bool bpf_map_support_seq_show(const struct bpf_map *map)
+{
+	return map->ops->map_seq_show_elem && map->ops->map_check_btf;
+}
+
 extern const struct bpf_map_ops bpf_map_offload_ops;
 
 /* function argument constraints */

include/linux/btf.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2018 Facebook */
+
+#ifndef _LINUX_BTF_H
+#define _LINUX_BTF_H 1
+
+#include <linux/types.h>
+
+struct btf;
+struct btf_type;
+union bpf_attr;
+
+extern const struct file_operations btf_fops;
+
+void btf_put(struct btf *btf);
+int btf_new_fd(const union bpf_attr *attr);
+struct btf *btf_get_by_fd(int fd);
+int btf_get_info_by_fd(const struct btf *btf,
+		       const union bpf_attr *attr,
+		       union bpf_attr __user *uattr);
+/* Figure out the size of a type_id.  If type_id is a modifier
+ * (e.g. const), it will be resolved to find out the type with size.
+ *
+ * For example:
+ * In describing "const void *",  type_id is "const" and "const"
+ * refers to "void *".  The return type will be "void *".
+ *
+ * If type_id is a simple "int", then return type will be "int".
+ *
+ * @btf: struct btf object
+ * @type_id: Find out the size of type_id. The type_id of the return
+ *           type is set to *type_id.
+ * @ret_size: It can be NULL.  If not NULL, the size of the return
+ *            type is set to *ret_size.
+ * Return: The btf_type (resolved to another type with size info if needed).
+ *         NULL is returned if type_id itself does not have size info
+ *         (e.g. void) or it cannot be resolved to another type that
+ *         has size info.
+ *         *type_id and *ret_size will not be changed in the
+ *         NULL return case.
+ */
+const struct btf_type *btf_type_id_size(const struct btf *btf,
+					u32 *type_id,
+					u32 *ret_size);
+void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
+		       struct seq_file *m);
+
+#endif

include/uapi/linux/bpf.h

@@ -95,6 +95,7 @@ enum bpf_cmd {
 	BPF_OBJ_GET_INFO_BY_FD,
 	BPF_PROG_QUERY,
 	BPF_RAW_TRACEPOINT_OPEN,
+	BPF_BTF_LOAD,
 };
 
 enum bpf_map_type {
@@ -279,6 +280,9 @@ union bpf_attr {
 					 */
 		char	map_name[BPF_OBJ_NAME_LEN];
 		__u32	map_ifindex;	/* ifindex of netdev to create on */
+		__u32	btf_fd;		/* fd pointing to a BTF type data */
+		__u32	btf_key_id;	/* BTF type_id of the key */
+		__u32	btf_value_id;	/* BTF type_id of the value */
 	};
 
 	struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
@@ -363,6 +367,14 @@ union bpf_attr {
 		__u64 name;
 		__u32 prog_fd;
 	} raw_tracepoint;
+
+	struct { /* anonymous struct for BPF_BTF_LOAD */
+		__aligned_u64	btf;
+		__aligned_u64	btf_log_buf;
+		__u32		btf_size;
+		__u32		btf_log_size;
+		__u32		btf_log_level;
+	};
 } __attribute__((aligned(8)));
 
 /* BPF helper function descriptions:

include/uapi/linux/btf.h

+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* Copyright (c) 2018 Facebook */
+#ifndef _UAPI__LINUX_BTF_H__
+#define _UAPI__LINUX_BTF_H__
+
+#include <linux/types.h>
+
+#define BTF_MAGIC	0xeB9F
+#define BTF_MAGIC_SWAP	0x9FeB
+#define BTF_VERSION	1
+#define BTF_FLAGS_COMPR	0x01
+
+struct btf_header {
+	__u16	magic;
+	__u8	version;
+	__u8	flags;
+
+	__u32	parent_label;
+	__u32	parent_name;
+
+	/* All offsets are in bytes relative to the end of this header */
+	__u32	label_off;	/* offset of label section	*/
+	__u32	object_off;	/* offset of data object section*/
+	__u32	func_off;	/* offset of function section	*/
+	__u32	type_off;	/* offset of type section	*/
+	__u32	str_off;	/* offset of string section	*/
+	__u32	str_len;	/* length of string section	*/
+};
+
+/* Max # of type identifier */
+#define BTF_MAX_TYPE	0x7fffffff
+/* Max offset into the string section */
+#define BTF_MAX_NAME_OFFSET	0x7fffffff
+/* Max # of struct/union/enum members or func args */
+#define BTF_MAX_VLEN	0xffff
+
+/* The type id is referring to a parent BTF */
+#define BTF_TYPE_PARENT(id)	(((id) >> 31) & 0x1)
+#define BTF_TYPE_ID(id)		((id) & BTF_MAX_TYPE)
+
+/* String is in the ELF string section */
+#define BTF_STR_TBL_ELF_ID(ref)	(((ref) >> 31) & 0x1)
+#define BTF_STR_OFFSET(ref)	((ref) & BTF_MAX_NAME_OFFSET)
+
+struct btf_type {
+	__u32 name;
+	/* "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    31: root
+	 */
+	__u32 info;
+	/* "size" is used by INT, ENUM, STRUCT and UNION.
+	 * "size" tells the size of the type it is describing.
+	 *
+	 * "type" is used by PTR, TYPEDEF, VOLATILE, CONST and RESTRICT.
+	 * "type" is a type_id referring to another type.
+	 */
+	union {
+		__u32 size;
+		__u32 type;
+	};
+};
+
+#define BTF_INFO_KIND(info)	(((info) >> 24) & 0x1f)
+#define BTF_INFO_ISROOT(info)	(!!(((info) >> 24) & 0x80))
+#define BTF_INFO_VLEN(info)	((info) & 0xffff)
+
+#define BTF_KIND_UNKN		0	/* Unknown	*/
+#define BTF_KIND_INT		1	/* Integer	*/
+#define BTF_KIND_PTR		2	/* Pointer	*/
+#define BTF_KIND_ARRAY		3	/* Array	*/
+#define BTF_KIND_STRUCT		4	/* Struct	*/
+#define BTF_KIND_UNION		5	/* Union	*/
+#define BTF_KIND_ENUM		6	/* Enumeration	*/
+#define BTF_KIND_FWD		7	/* Forward	*/
+#define BTF_KIND_TYPEDEF	8	/* Typedef	*/
+#define BTF_KIND_VOLATILE	9	/* Volatile	*/
+#define BTF_KIND_CONST		10	/* Const	*/
+#define BTF_KIND_RESTRICT	11	/* Restrict	*/
+#define BTF_KIND_MAX		11
+#define NR_BTF_KINDS		12
+
+/* For some specific BTF_KIND, "struct btf_type" is immediately
+ * followed by extra data.
+ */
+
+/* BTF_KIND_INT is followed by a u32 and the following
+ * is the 32 bits arrangement:
+ */
+#define BTF_INT_ENCODING(VAL)	(((VAL) & 0xff000000) >> 24)
+#define BTF_INT_OFFSET(VAL)	(((VAL  & 0x00ff0000)) >> 16)
+#define BTF_INT_BITS(VAL)	((VAL)  & 0x0000ffff)
+
+/* Attributes stored in the BTF_INT_ENCODING */
+#define BTF_INT_SIGNED	0x1
+#define BTF_INT_CHAR	0x2
+#define BTF_INT_BOOL	0x4
+#define BTF_INT_VARARGS	0x8
+
+/* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
+ * The exact number of btf_enum is stored in the vlen (of the
+ * info in "struct btf_type").
+ */
+struct btf_enum {
+	__u32	name;
+	__s32	val;
+};
+
+/* BTF_KIND_ARRAY is followed by one "struct btf_array" */
+struct btf_array {
+	__u32	type;
+	__u32	index_type;
+	__u32	nelems;
+};
+
+/* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
+ * by multiple "struct btf_member".  The exact number
+ * of btf_member is stored in the vlen (of the info in
+ * "struct btf_type").
+ */
+struct btf_member {
+	__u32	name;
+	__u32	type;
+	__u32	offset;	/* offset in bits */
+};
+
+#endif /* _UAPI__LINUX_BTF_H__ */

kernel/bpf/Makefile

@@ -4,6 +4,7 @@ obj-y := core.o
 obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o
 obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o
 obj-$(CONFIG_BPF_SYSCALL) += disasm.o
+obj-$(CONFIG_BPF_SYSCALL) += btf.o
 ifeq ($(CONFIG_NET),y)
 obj-$(CONFIG_BPF_SYSCALL) += devmap.o
 obj-$(CONFIG_BPF_SYSCALL) += cpumap.o

kernel/bpf/arraymap.c

@@ -11,11 +11,13 @@
  * General Public License for more details.
  */
 #include <linux/bpf.h>
+#include <linux/btf.h>
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/mm.h>
 #include <linux/filter.h>
 #include <linux/perf_event.h>
+#include <uapi/linux/btf.h>
 
 #include "map_in_map.h"
 
@@ -336,6 +338,52 @@ static void array_map_free(struct bpf_map *map)
 	bpf_map_area_free(array);
 }
 
+static void array_map_seq_show_elem(struct bpf_map *map, void *key,
+				    struct seq_file *m)
+{
+	void *value;
+
+	rcu_read_lock();
+
+	value = array_map_lookup_elem(map, key);
+	if (!value) {
+		rcu_read_unlock();
+		return;
+	}
+
+	seq_printf(m, "%u: ", *(u32 *)key);
+	btf_type_seq_show(map->btf, map->btf_value_id, value, m);
+	seq_puts(m, "\n");
+
+	rcu_read_unlock();
+}
+
+static int array_map_check_btf(const struct bpf_map *map, const struct btf *btf,
+			       u32 btf_key_id, u32 btf_value_id)
+{
+	const struct btf_type *key_type, *value_type;
+	u32 key_size, value_size;
+	u32 int_data;
+
+	key_type = btf_type_id_size(btf, &btf_key_id, &key_size);
+	if (!key_type || BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
+		return -EINVAL;
+
+	int_data = *(u32 *)(key_type + 1);
+	/* bpf array can only take a u32 key.  This check makes
+	 * sure that the btf matches the attr used during map_create.
+	 */
+	if (BTF_INT_BITS(int_data) != 32 || key_size != 4 ||
+	    BTF_INT_OFFSET(int_data))
+		return -EINVAL;
+
+	value_type = btf_type_id_size(btf, &btf_value_id, &value_size);
+	if (!value_type || value_size > map->value_size)
+		return -EINVAL;
+
+	return 0;
+}
+
 const struct bpf_map_ops array_map_ops = {
 	.map_alloc_check = array_map_alloc_check,
 	.map_alloc = array_map_alloc,
@@ -345,6 +393,8 @@ const struct bpf_map_ops array_map_ops = {
 	.map_update_elem = array_map_update_elem,
 	.map_delete_elem = array_map_delete_elem,
 	.map_gen_lookup = array_map_gen_lookup,
+	.map_seq_show_elem = array_map_seq_show_elem,
+	.map_check_btf = array_map_check_btf,
 };
 
 const struct bpf_map_ops percpu_array_map_ops = {

kernel/bpf/btf.c

+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2018 Facebook */
+
+#include <uapi/linux/btf.h>
+#include <uapi/linux/types.h>
+#include <linux/seq_file.h>
+#include <linux/compiler.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/anon_inodes.h>
+#include <linux/file.h>
+#include <linux/uaccess.h>
+#include <linux/kernel.h>
+#include <linux/bpf_verifier.h>
+#include <linux/btf.h>
+
+/* BTF (BPF Type Format) is the meta data format which describes
+ * the data types of BPF program/map.  Hence, it basically focus
+ * on the C programming language which the modern BPF is primary
+ * using.
+ *
+ * ELF Section:
+ * ~~~~~~~~~~~
+ * The BTF data is stored under the ".BTF" ELF section
+ *
+ * struct btf_type:
+ * ~~~~~~~~~~~~~~~
+ * Each 'struct btf_type' object describes a C data type.
+ * Depending on the type it is describing, a 'struct btf_type'
+ * object may be followed by more data.  F.e.
+ * To describe an array, 'struct btf_type' is followed by
+ * 'struct btf_array'.
+ *
+ * 'struct btf_type' and any extra data following it are
+ * 4 bytes aligned.
+ *
+ * Type section:
+ * ~~~~~~~~~~~~~
+ * The BTF type section contains a list of 'struct btf_type' objects.
+ * Each one describes a C type.  Recall from the above section
+ * that a 'struct btf_type' object could be immediately followed by extra
+ * data in order to desribe some particular C types.
+ *
+ * type_id:
+ * ~~~~~~~
+ * Each btf_type object is identified by a type_id.  The type_id
+ * is implicitly implied by the location of the btf_type object in
+ * the BTF type section.  The first one has type_id 1.  The second
+ * one has type_id 2...etc.  Hence, an earlier btf_type has
+ * a smaller type_id.
+ *
+ * A btf_type object may refer to another btf_type object by using
+ * type_id (i.e. the "type" in the "struct btf_type").
+ *
+ * NOTE that we cannot assume any reference-order.
+ * A btf_type object can refer to an earlier btf_type object
+ * but it can also refer to a later btf_type object.
+ *
+ * For example, to describe "const void *".  A btf_type
+ * object describing "const" may refer to another btf_type
+ * object describing "void *".  This type-reference is done
+ * by specifying type_id:
+ *
+ * [1] CONST (anon) type_id=2
+ * [2] PTR (anon) type_id=0
+ *
+ * The above is the btf_verifier debug log:
+ *   - Each line started with "[?]" is a btf_type object
+ *   - [?] is the type_id of the btf_type object.
+ *   - CONST/PTR is the BTF_KIND_XXX
+ *   - "(anon)" is the name of the type.  It just
+ *     happens that CONST and PTR has no name.
+ *   - type_id=XXX is the 'u32 type' in btf_type
+ *
+ * NOTE: "void" has type_id 0
+ *
+ * String section:
+ * ~~~~~~~~~~~~~~
+ * The BTF string section contains the names used by the type section.
+ * Each string is referred by an "offset" from the beginning of the
+ * string section.
+ *
+ * Each string is '\0' terminated.
+ *
+ * The first character in the string section must be '\0'
+ * which is used to mean 'anonymous'. Some btf_type may not
+ * have a name.
+ */
+
+/* BTF verification:
+ *
+ * To verify BTF data, two passes are needed.
+ *
+ * Pass #1
+ * ~~~~~~~
+ * The first pass is to collect all btf_type objects to
+ * an array: "btf->types".
+ *
+ * Depending on the C type that a btf_type is describing,
+ * a btf_type may be followed by extra data.  We don't know
+ * how many btf_type is there, and more importantly we don't
+ * know where each btf_type is located in the type section.
+ *
+ * Without knowing the location of each type_id, most verifications
+ * cannot be done.  e.g. an earlier btf_type may refer to a later
+ * btf_type (recall the "const void *" above), so we cannot
+ * check this type-reference in the first pass.
+ *
+ * In the first pass, it still does some verifications (e.g.
+ * checking the name is a valid offset to the string section).
+ *
+ * Pass #2
+ * ~~~~~~~
+ * The main focus is to resolve a btf_type that is referring
+ * to another type.
+ *
+ * We have to ensure the referring type:
+ * 1) does exist in the BTF (i.e. in btf->types[])
+ * 2) does not cause a loop:
+ *	struct A {
+ *		struct B b;
+ *	};
+ *
+ *	struct B {
+ *		struct A a;
+ *	};
+ *
+ * btf_type_needs_resolve() decides if a btf_type needs
+ * to be resolved.
+ *
+ * The needs_resolve type implements the "resolve()" ops which
+ * essentially does a DFS and detects backedge.
+ *
+ * During resolve (or DFS), different C types have different
+ * "RESOLVED" conditions.
+ *
+ * When resolving a BTF_KIND_STRUCT, we need to resolve all its
+ * members because a member is always referring to another
+ * type.  A struct's member can be treated as "RESOLVED" if
+ * it is referring to a BTF_KIND_PTR.  Otherwise, the
+ * following valid C struct would be rejected:
+ *
+ *	struct A {
+ *		int m;
+ *		struct A *a;
+ *	};
+ *
+ * When resolving a BTF_KIND_PTR, it needs to keep resolving if
+ * it is referring to another BTF_KIND_PTR.  Otherwise, we cannot
+ * detect a pointer loop, e.g.:
+ * BTF_KIND_CONST -> BTF_KIND_PTR -> BTF_KIND_CONST -> BTF_KIND_PTR +
+ *                        ^                                         |
+ *                        +-----------------------------------------+
+ *
+ */
+
+#define BITS_PER_U64 (sizeof(u64) * BITS_PER_BYTE)
+#define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1)
+#define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK)
+#define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3)
+#define BITS_ROUNDUP_BYTES(bits) \
+	(BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))
+
+/* 16MB for 64k structs and each has 16 members and
+ * a few MB spaces for the string section.
+ * The hard limit is S32_MAX.
+ */
+#define BTF_MAX_SIZE (16 * 1024 * 1024)
+/* 64k. We can raise it later. The hard limit is S32_MAX. */
+#define BTF_MAX_NR_TYPES 65535
+
+#define for_each_member(i, struct_type, member)			\
+	for (i = 0, member = btf_type_member(struct_type);	\
+	     i < btf_type_vlen(struct_type);			\
+	     i++, member++)
+
+#define for_each_member_from(i, from, struct_type, member)		\
+	for (i = from, member = btf_type_member(struct_type) + from;	\
+	     i < btf_type_vlen(struct_type);				\
+	     i++, member++)
+
+struct btf {
+	union {
+		struct btf_header *hdr;
+		void *data;
+	};
+	struct btf_type **types;
+	u32 *resolved_ids;
+	u32 *resolved_sizes;
+	const char *strings;
+	void *nohdr_data;
+	u32 nr_types;
+	u32 types_size;
+	u32 data_size;
+	refcount_t refcnt;
+};
+
+enum verifier_phase {
+	CHECK_META,
+	CHECK_TYPE,
+};
+
+struct resolve_vertex {
+	const struct btf_type *t;
+	u32 type_id;
+	u16 next_member;
+};
+
+enum visit_state {
+	NOT_VISITED,
+	VISITED,
+	RESOLVED,
+};
+
+enum resolve_mode {
+	RESOLVE_TBD,	/* To Be Determined */
+	RESOLVE_PTR,	/* Resolving for Pointer */
+	RESOLVE_STRUCT_OR_ARRAY,	/* Resolving for struct/union
+					 * or array
+					 */
+};
+
+#define MAX_RESOLVE_DEPTH 32
+
+struct btf_verifier_env {
+	struct btf *btf;
+	u8 *visit_states;
+	struct resolve_vertex stack[MAX_RESOLVE_DEPTH];
+	struct bpf_verifier_log log;
+	u32 log_type_id;
+	u32 top_stack;
+	enum verifier_phase phase;
+	enum resolve_mode resolve_mode;
+};
+
+static const char * const btf_kind_str[NR_BTF_KINDS] = {
+	[BTF_KIND_UNKN]		= "UNKNOWN",
+	[BTF_KIND_INT]		= "INT",
+	[BTF_KIND_PTR]		= "PTR",
+	[BTF_KIND_ARRAY]	= "ARRAY",
+	[BTF_KIND_STRUCT]	= "STRUCT",
+	[BTF_KIND_UNION]	= "UNION",
+	[BTF_KIND_ENUM]		= "ENUM",
+	[BTF_KIND_FWD]		= "FWD",
+	[BTF_KIND_TYPEDEF]	= "TYPEDEF",
+	[BTF_KIND_VOLATILE]	= "VOLATILE",
+	[BTF_KIND_CONST]	= "CONST",
+	[BTF_KIND_RESTRICT]	= "RESTRICT",
+};
+
+struct btf_kind_operations {
+	s32 (*check_meta)(struct btf_verifier_env *env,
+			  const struct btf_type *t,
+			  u32 meta_left);
+	int (*resolve)(struct btf_verifier_env *env,
+		       const struct resolve_vertex *v);
+	int (*check_member)(struct btf_verifier_env *env,
+			    const struct btf_type *struct_type,
+			    const struct btf_member *member,
+			    const struct btf_type *member_type);
+	void (*log_details)(struct btf_verifier_env *env,
+			    const struct btf_type *t);
+	void (*seq_show)(const struct btf *btf, const struct btf_type *t,
+			 u32 type_id, void *data, u8 bits_offsets,
+			 struct seq_file *m);
+};
+
+static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS];
+static struct btf_type btf_void;
+
+static bool btf_type_is_modifier(const struct btf_type *t)
+{
+	/* Some of them is not strictly a C modifier
+	 * but they are grouped into the same bucket
+	 * for BTF concern:
+	 *   A type (t) that refers to another
+	 *   type through t->type AND its size cannot
+	 *   be determined without following the t->type.
+	 *
+	 * ptr does not fall into this bucket
+	 * because its size is always sizeof(void *).
+	 */
+	switch (BTF_INFO_KIND(t->info)) {
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_CONST:
+	case BTF_KIND_RESTRICT:
+		return true;
+	}
+
+	return false;
+}
+
+static bool btf_type_is_void(const struct btf_type *t)
+{
+	/* void => no type and size info.
+	 * Hence, FWD is also treated as void.
+	 */
+	return t == &btf_void || BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
+}
+
+static bool btf_type_is_void_or_null(const struct btf_type *t)
+{
+	return !t || btf_type_is_void(t);
+}
+
+/* union is only a special case of struct:
+ * all its offsetof(member) == 0
+ */
+static bool btf_type_is_struct(const struct btf_type *t)
+{
+	u8 kind = BTF_INFO_KIND(t->info);
+
+	return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
+}
+
+static bool btf_type_is_array(const struct btf_type *t)
+{
+	return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY;
+}
+
+static bool btf_type_is_ptr(const struct btf_type *t)
+{
+	return BTF_INFO_KIND(t->info) == BTF_KIND_PTR;
+}
+
+static bool btf_type_is_int(const struct btf_type *t)
+{
+	return BTF_INFO_KIND(t->info) == BTF_KIND_INT;
+}
+
+/* What types need to be resolved?
+ *
+ * btf_type_is_modifier() is an obvious one.
+ *
+ * btf_type_is_struct() because its member refers to
+ * another type (through member->type).
+
+ * btf_type_is_array() because its element (array->type)
+ * refers to another type.  Array can be thought of a
+ * special case of struct while array just has the same
+ * member-type repeated by array->nelems of times.
+ */
+static bool btf_type_needs_resolve(const struct btf_type *t)
+{
+	return btf_type_is_modifier(t) ||
+		btf_type_is_ptr(t) ||
+		btf_type_is_struct(t) ||
+		btf_type_is_array(t);
+}
+
+/* t->size can be used */
+static bool btf_type_has_size(const struct btf_type *t)
+{
+	switch (BTF_INFO_KIND(t->info)) {
+	case BTF_KIND_INT:
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+	case BTF_KIND_ENUM:
+		return true;
+	}
+
+	return false;
+}
+
+static const char *btf_int_encoding_str(u8 encoding)
+{
+	if (encoding == 0)
+		return "(none)";
+	else if (encoding == BTF_INT_SIGNED)
+		return "SIGNED";
+	else if (encoding == BTF_INT_CHAR)
+		return "CHAR";
+	else if (encoding == BTF_INT_BOOL)
+		return "BOOL";
+	else if (encoding == BTF_INT_VARARGS)
+		return "VARARGS";
+	else
+		return "UNKN";
+}
+
+static u16 btf_type_vlen(const struct btf_type *t)
+{
+	return BTF_INFO_VLEN(t->info);
+}
+
+static u32 btf_type_int(const struct btf_type *t)
+{
+	return *(u32 *)(t + 1);
+}
+
+static const struct btf_array *btf_type_array(const struct btf_type *t)
+{
+	return (const struct btf_array *)(t + 1);
+}
+
+static const struct btf_member *btf_type_member(const struct btf_type *t)
+{
+	return (const struct btf_member *)(t + 1);
+}
+
+static const struct btf_enum *btf_type_enum(const struct btf_type *t)
+{
+	return (const struct btf_enum *)(t + 1);
+}
+
+static const struct btf_kind_operations *btf_type_ops(const struct btf_type *t)
+{
+	return kind_ops[BTF_INFO_KIND(t->info)];
+}
+
+static bool btf_name_offset_valid(const struct btf *btf, u32 offset)
+{
+	return !BTF_STR_TBL_ELF_ID(offset) &&
+		BTF_STR_OFFSET(offset) < btf->hdr->str_len;
+}
+
+static const char *btf_name_by_offset(const struct btf *btf, u32 offset)
+{
+	if (!BTF_STR_OFFSET(offset))
+		return "(anon)";
+	else if (BTF_STR_OFFSET(offset) < btf->hdr->str_len)
+		return &btf->strings[BTF_STR_OFFSET(offset)];
+	else
+		return "(invalid-name-offset)";
+}
+
+static const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id)
+{
+	if (type_id > btf->nr_types)
+		return NULL;
+
+	return btf->types[type_id];
+}
+
+__printf(2, 3) static void __btf_verifier_log(struct bpf_verifier_log *log,
+					      const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	bpf_verifier_vlog(log, fmt, args);
+	va_end(args);
+}
+
+__printf(2, 3) static void btf_verifier_log(struct btf_verifier_env *env,
+					    const char *fmt, ...)
+{
+	struct bpf_verifier_log *log = &env->log;
+	va_list args;
+
+	if (!bpf_verifier_log_needed(log))
+		return;
+
+	va_start(args, fmt);
+	bpf_verifier_vlog(log, fmt, args);
+	va_end(args);
+}
+
+__printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env *env,
+						   const struct btf_type *t,
+						   bool log_details,
+						   const char *fmt, ...)
+{
+	struct bpf_verifier_log *log = &env->log;
+	u8 kind = BTF_INFO_KIND(t->info);
+	struct btf *btf = env->btf;
+	va_list args;
+
+	if (!bpf_verifier_log_needed(log))
+		return;
+
+	__btf_verifier_log(log, "[%u] %s %s%s",
+			   env->log_type_id,
+			   btf_kind_str[kind],
+			   btf_name_by_offset(btf, t->name),
+			   log_details ? " " : "");
+
+	if (log_details)
+		btf_type_ops(t)->log_details(env, t);
+
+	if (fmt && *fmt) {
+		__btf_verifier_log(log, " ");
+		va_start(args, fmt);
+		bpf_verifier_vlog(log, fmt, args);
+		va_end(args);
+	}
+
+	__btf_verifier_log(log, "\n");
+}
+
+#define btf_verifier_log_type(env, t, ...) \
+	__btf_verifier_log_type((env), (t), true, __VA_ARGS__)
+#define btf_verifier_log_basic(env, t, ...) \
+	__btf_verifier_log_type((env), (t), false, __VA_ARGS__)
+
+__printf(4, 5)
+static void btf_verifier_log_member(struct btf_verifier_env *env,
+				    const struct btf_type *struct_type,
+				    const struct btf_member *member,
+				    const char *fmt, ...)
+{
+	struct bpf_verifier_log *log = &env->log;
+	struct btf *btf = env->btf;
+	va_list args;
+
+	if (!bpf_verifier_log_needed(log))
+		return;
+
+	/* The CHECK_META phase already did a btf dump.
+	 *
+	 * If member is logged again, it must hit an error in
+	 * parsing this member.  It is useful to print out which
+	 * struct this member belongs to.
+	 */
+	if (env->phase != CHECK_META)
+		btf_verifier_log_type(env, struct_type, NULL);
+
+	__btf_verifier_log(log, "\t%s type_id=%u bits_offset=%u",
+			   btf_name_by_offset(btf, member->name),
+			   member->type, member->offset);
+
+	if (fmt && *fmt) {
+		__btf_verifier_log(log, " ");
+		va_start(args, fmt);
+		bpf_verifier_vlog(log, fmt, args);
+		va_end(args);
+	}
+
+	__btf_verifier_log(log, "\n");
+}
+
+static void btf_verifier_log_hdr(struct btf_verifier_env *env)
+{
+	struct bpf_verifier_log *log = &env->log;
+	const struct btf *btf = env->btf;
+	const struct btf_header *hdr;
+
+	if (!bpf_verifier_log_needed(log))
+		return;
+
+	hdr = btf->hdr;
+	__btf_verifier_log(log, "magic: 0x%x\n", hdr->magic);
+	__btf_verifier_log(log, "version: %u\n", hdr->version);
+	__btf_verifier_log(log, "flags: 0x%x\n", hdr->flags);
+	__btf_verifier_log(log, "parent_label: %u\n", hdr->parent_label);
+	__btf_verifier_log(log, "parent_name: %u\n", hdr->parent_name);
+	__btf_verifier_log(log, "label_off: %u\n", hdr->label_off);
+	__btf_verifier_log(log, "object_off: %u\n", hdr->object_off);
+	__btf_verifier_log(log, "func_off: %u\n", hdr->func_off);
+	__btf_verifier_log(log, "type_off: %u\n", hdr->type_off);
+	__btf_verifier_log(log, "str_off: %u\n", hdr->str_off);
+	__btf_verifier_log(log, "str_len: %u\n", hdr->str_len);
+	__btf_verifier_log(log, "btf_total_size: %u\n", btf->data_size);
+}
+
+static int btf_add_type(struct btf_verifier_env *env, struct btf_type *t)
+{
+	struct btf *btf = env->btf;
+
+	/* < 2 because +1 for btf_void which is always in btf->types[0].
+	 * btf_void is not accounted in btf->nr_types because btf_void
+	 * does not come from the BTF file.
+	 */
+	if (btf->types_size - btf->nr_types < 2) {
+		/* Expand 'types' array */
+
+		struct btf_type **new_types;
+		u32 expand_by, new_size;
+
+		if (btf->types_size == BTF_MAX_NR_TYPES) {
+			btf_verifier_log(env, "Exceeded max num of types");
+			return -E2BIG;
+		}
+
+		expand_by = max_t(u32, btf->types_size >> 2, 16);
+		new_size = min_t(u32, BTF_MAX_NR_TYPES,
+				 btf->types_size + expand_by);
+
+		new_types = kvzalloc(new_size * sizeof(*new_types),
+				     GFP_KERNEL | __GFP_NOWARN);
+		if (!new_types)
+			return -ENOMEM;
+
+		if (btf->nr_types == 0)
+			new_types[0] = &btf_void;
+		else
+			memcpy(new_types, btf->types,
+			       sizeof(*btf->types) * (btf->nr_types + 1));
+
+		kvfree(btf->types);
+		btf->types = new_types;
+		btf->types_size = new_size;
+	}
+
+	btf->types[++(btf->nr_types)] = t;
+
+	return 0;
+}
+
+static void btf_free(struct btf *btf)
+{
+	kvfree(btf->types);
+	kvfree(btf->resolved_sizes);
+	kvfree(btf->resolved_ids);
+	kvfree(btf->data);
+	kfree(btf);
+}
+
+static void btf_get(struct btf *btf)
+{
+	refcount_inc(&btf->refcnt);
+}
+
+void btf_put(struct btf *btf)
+{
+	if (btf && refcount_dec_and_test(&btf->refcnt))
+		btf_free(btf);
+}
+
+static int env_resolve_init(struct btf_verifier_env *env)
+{
+	struct btf *btf = env->btf;
+	u32 nr_types = btf->nr_types;
+	u32 *resolved_sizes = NULL;
+	u32 *resolved_ids = NULL;
+	u8 *visit_states = NULL;
+
+	/* +1 for btf_void */
+	resolved_sizes = kvzalloc((nr_types + 1) * sizeof(*resolved_sizes),
+				  GFP_KERNEL | __GFP_NOWARN);
+	if (!resolved_sizes)
+		goto nomem;
+
+	resolved_ids = kvzalloc((nr_types + 1) * sizeof(*resolved_ids),
+				GFP_KERNEL | __GFP_NOWARN);
+	if (!resolved_ids)
+		goto nomem;
+
+	visit_states = kvzalloc((nr_types + 1) * sizeof(*visit_states),
+				GFP_KERNEL | __GFP_NOWARN);
+	if (!visit_states)
+		goto nomem;
+
+	btf->resolved_sizes = resolved_sizes;
+	btf->resolved_ids = resolved_ids;
+	env->visit_states = visit_states;
+
+	return 0;
+
+nomem:
+	kvfree(resolved_sizes);
+	kvfree(resolved_ids);
+	kvfree(visit_states);
+	return -ENOMEM;
+}
+
+static void btf_verifier_env_free(struct btf_verifier_env *env)
+{
+	kvfree(env->visit_states);
+	kfree(env);
+}
+
+static bool env_type_is_resolve_sink(const struct btf_verifier_env *env,
+				     const struct btf_type *next_type)
+{
+	switch (env->resolve_mode) {
+	case RESOLVE_TBD:
+		/* int, enum or void is a sink */
+		return !btf_type_needs_resolve(next_type);
+	case RESOLVE_PTR:
+		/* int, enum, void, struct or array is a sink for ptr */
+		return !btf_type_is_modifier(next_type) &&
+			!btf_type_is_ptr(next_type);
+	case RESOLVE_STRUCT_OR_ARRAY:
+		/* int, enum, void or ptr is a sink for struct and array */
+		return !btf_type_is_modifier(next_type) &&
+			!btf_type_is_array(next_type) &&
+			!btf_type_is_struct(next_type);
+	default:
+		BUG_ON(1);
+	}
+}
+
+static bool env_type_is_resolved(const struct btf_verifier_env *env,
+				 u32 type_id)
+{
+	return env->visit_states[type_id] == RESOLVED;
+}
+
+static int env_stack_push(struct btf_verifier_env *env,
+			  const struct btf_type *t, u32 type_id)
+{
+	struct resolve_vertex *v;
+
+	if (env->top_stack == MAX_RESOLVE_DEPTH)
+		return -E2BIG;
+
+	if (env->visit_states[type_id] != NOT_VISITED)
+		return -EEXIST;
+
+	env->visit_states[type_id] = VISITED;
+
+	v = &env->stack[env->top_stack++];
+	v->t = t;
+	v->type_id = type_id;
+	v->next_member = 0;
+
+	if (env->resolve_mode == RESOLVE_TBD) {
+		if (btf_type_is_ptr(t))
+			env->resolve_mode = RESOLVE_PTR;
+		else if (btf_type_is_struct(t) || btf_type_is_array(t))
+			env->resolve_mode = RESOLVE_STRUCT_OR_ARRAY;
+	}
+
+	return 0;
+}
+
+static void env_stack_set_next_member(struct btf_verifier_env *env,
+				      u16 next_member)
+{
+	env->stack[env->top_stack - 1].next_member = next_member;
+}
+
+static void env_stack_pop_resolved(struct btf_verifier_env *env,
+				   u32 resolved_type_id,
+				   u32 resolved_size)
+{
+	u32 type_id = env->stack[--(env->top_stack)].type_id;
+	struct btf *btf = env->btf;
+
+	btf->resolved_sizes[type_id] = resolved_size;
+	btf->resolved_ids[type_id] = resolved_type_id;
+	env->visit_states[type_id] = RESOLVED;
+}
+
+static const struct resolve_vertex *env_stack_peak(struct btf_verifier_env *env)
+{
+	return env->top_stack ? &env->stack[env->top_stack - 1] : NULL;
+}
+
+/* The input param "type_id" must point to a needs_resolve type */
+static const struct btf_type *btf_type_id_resolve(const struct btf *btf,
+						  u32 *type_id)
+{
+	*type_id = btf->resolved_ids[*type_id];
+	return btf_type_by_id(btf, *type_id);
+}
+
+const struct btf_type *btf_type_id_size(const struct btf *btf,
+					u32 *type_id, u32 *ret_size)
+{
+	const struct btf_type *size_type;
+	u32 size_type_id = *type_id;
+	u32 size = 0;
+
+	size_type = btf_type_by_id(btf, size_type_id);
+	if (btf_type_is_void_or_null(size_type))
+		return NULL;
+
+	if (btf_type_has_size(size_type)) {
+		size = size_type->size;
+	} else if (btf_type_is_array(size_type)) {
+		size = btf->resolved_sizes[size_type_id];
+	} else if (btf_type_is_ptr(size_type)) {
+		size = sizeof(void *);
+	} else {
+		if (WARN_ON_ONCE(!btf_type_is_modifier(size_type)))
+			return NULL;
+
+		size = btf->resolved_sizes[size_type_id];
+		size_type_id = btf->resolved_ids[size_type_id];
+		size_type = btf_type_by_id(btf, size_type_id);
+		if (btf_type_is_void(size_type))
+			return NULL;
+	}
+
+	*type_id = size_type_id;
+	if (ret_size)
+		*ret_size = size;
+
+	return size_type;
+}
+
+static int btf_df_check_member(struct btf_verifier_env *env,
+			       const struct btf_type *struct_type,
+			       const struct btf_member *member,
+			       const struct btf_type *member_type)
+{
+	btf_verifier_log_basic(env, struct_type,
+			       "Unsupported check_member");
+	return -EINVAL;
+}
+
+static int btf_df_resolve(struct btf_verifier_env *env,
+			  const struct resolve_vertex *v)
+{
+	btf_verifier_log_basic(env, v->t, "Unsupported resolve");
+	return -EINVAL;
+}
+
+static void btf_df_seq_show(const struct btf *btf, const struct btf_type *t,
+			    u32 type_id, void *data, u8 bits_offsets,
+			    struct seq_file *m)
+{
+	seq_printf(m, "<unsupported kind:%u>", BTF_INFO_KIND(t->info));
+}
+
+static int btf_int_check_member(struct btf_verifier_env *env,
+				const struct btf_type *struct_type,
+				const struct btf_member *member,
+				const struct btf_type *member_type)
+{
+	u32 int_data = btf_type_int(member_type);
+	u32 struct_bits_off = member->offset;
+	u32 struct_size = struct_type->size;
+	u32 nr_copy_bits;
+	u32 bytes_offset;
+
+	if (U32_MAX - struct_bits_off < BTF_INT_OFFSET(int_data)) {
+		btf_verifier_log_member(env, struct_type, member,
+					"bits_offset exceeds U32_MAX");
+		return -EINVAL;
+	}
+
+	struct_bits_off += BTF_INT_OFFSET(int_data);
+	bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
+	nr_copy_bits = BTF_INT_BITS(int_data) +
+		BITS_PER_BYTE_MASKED(struct_bits_off);
+
+	if (nr_copy_bits > BITS_PER_U64) {
+		btf_verifier_log_member(env, struct_type, member,
+					"nr_copy_bits exceeds 64");
+		return -EINVAL;
+	}
+
+	if (struct_size < bytes_offset ||
+	    struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
+		btf_verifier_log_member(env, struct_type, member,
+					"Member exceeds struct_size");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static s32 btf_int_check_meta(struct btf_verifier_env *env,
+			      const struct btf_type *t,
+			      u32 meta_left)
+{
+	u32 int_data, nr_bits, meta_needed = sizeof(int_data);
+	u16 encoding;
+
+	if (meta_left < meta_needed) {
+		btf_verifier_log_basic(env, t,
+				       "meta_left:%u meta_needed:%u",
+				       meta_left, meta_needed);
+		return -EINVAL;
+	}
+
+	if (btf_type_vlen(t)) {
+		btf_verifier_log_type(env, t, "vlen != 0");
+		return -EINVAL;
+	}
+
+	int_data = btf_type_int(t);
+	nr_bits = BTF_INT_BITS(int_data) + BTF_INT_OFFSET(int_data);
+
+	if (nr_bits > BITS_PER_U64) {
+		btf_verifier_log_type(env, t, "nr_bits exceeds %zu",
+				      BITS_PER_U64);
+		return -EINVAL;
+	}
+
+	if (BITS_ROUNDUP_BYTES(nr_bits) > t->size) {
+		btf_verifier_log_type(env, t, "nr_bits exceeds type_size");
+		return -EINVAL;
+	}
+
+	encoding = BTF_INT_ENCODING(int_data);
+	if (encoding &&
+	    encoding != BTF_INT_SIGNED &&
+	    encoding != BTF_INT_CHAR &&
+	    encoding != BTF_INT_BOOL &&
+	    encoding != BTF_INT_VARARGS) {
+		btf_verifier_log_type(env, t, "Unsupported encoding");
+		return -ENOTSUPP;
+	}
+
+	btf_verifier_log_type(env, t, NULL);
+
+	return meta_needed;
+}
+
+static void btf_int_log(struct btf_verifier_env *env,
+			const struct btf_type *t)
+{
+	int int_data = btf_type_int(t);
+
+	btf_verifier_log(env,
+			 "size=%u bits_offset=%u nr_bits=%u encoding=%s",
+			 t->size, BTF_INT_OFFSET(int_data),
+			 BTF_INT_BITS(int_data),
+			 btf_int_encoding_str(BTF_INT_ENCODING(int_data)));
+}
+
+static void btf_int_bits_seq_show(const struct btf *btf,
+				  const struct btf_type *t,
+				  void *data, u8 bits_offset,
+				  struct seq_file *m)
+{
+	u32 int_data = btf_type_int(t);
+	u16 nr_bits = BTF_INT_BITS(int_data);
+	u16 total_bits_offset;
+	u16 nr_copy_bytes;
+	u16 nr_copy_bits;
+	u8 nr_upper_bits;
+	union {
+		u64 u64_num;
+		u8  u8_nums[8];
+	} print_num;
+
+	total_bits_offset = bits_offset + BTF_INT_OFFSET(int_data);
+	data += BITS_ROUNDDOWN_BYTES(total_bits_offset);
+	bits_offset = BITS_PER_BYTE_MASKED(total_bits_offset);
+	nr_copy_bits = nr_bits + bits_offset;
+	nr_copy_bytes = BITS_ROUNDUP_BYTES(nr_copy_bits);
+
+	print_num.u64_num = 0;
+	memcpy(&print_num.u64_num, data, nr_copy_bytes);
+
+	/* Ditch the higher order bits */
+	nr_upper_bits = BITS_PER_BYTE_MASKED(nr_copy_bits);
+	if (nr_upper_bits) {
+		/* We need to mask out some bits of the upper byte. */
+		u8 mask = (1 << nr_upper_bits) - 1;
+
+		print_num.u8_nums[nr_copy_bytes - 1] &= mask;
+	}
+
+	print_num.u64_num >>= bits_offset;
+
+	seq_printf(m, "0x%llx", print_num.u64_num);
+}
+
+static void btf_int_seq_show(const struct btf *btf, const struct btf_type *t,
+			     u32 type_id, void *data, u8 bits_offset,
+			     struct seq_file *m)
+{
+	u32 int_data = btf_type_int(t);
+	u8 encoding = BTF_INT_ENCODING(int_data);
+	bool sign = encoding & BTF_INT_SIGNED;
+	u32 nr_bits = BTF_INT_BITS(int_data);
+
+	if (bits_offset || BTF_INT_OFFSET(int_data) ||
+	    BITS_PER_BYTE_MASKED(nr_bits)) {
+		btf_int_bits_seq_show(btf, t, data, bits_offset, m);
+		return;
+	}
+
+	switch (nr_bits) {
+	case 64:
+		if (sign)
+			seq_printf(m, "%lld", *(s64 *)data);
+		else
+			seq_printf(m, "%llu", *(u64 *)data);
+		break;
+	case 32:
+		if (sign)
+			seq_printf(m, "%d", *(s32 *)data);
+		else
+			seq_printf(m, "%u", *(u32 *)data);
+		break;
+	case 16:
+		if (sign)
+			seq_printf(m, "%d", *(s16 *)data);
+		else
+			seq_printf(m, "%u", *(u16 *)data);
+		break;
+	case 8:
+		if (sign)
+			seq_printf(m, "%d", *(s8 *)data);
+		else
+			seq_printf(m, "%u", *(u8 *)data);
+		break;
+	default:
+		btf_int_bits_seq_show(btf, t, data, bits_offset, m);
+	}
+}
+
+static const struct btf_kind_operations int_ops = {
+	.check_meta = btf_int_check_meta,
+	.resolve = btf_df_resolve,
+	.check_member = btf_int_check_member,
+	.log_details = btf_int_log,
+	.seq_show = btf_int_seq_show,
+};
+
+static int btf_modifier_check_member(struct btf_verifier_env *env,
+				     const struct btf_type *struct_type,
+				     const struct btf_member *member,
+				     const struct btf_type *member_type)
+{
+	const struct btf_type *resolved_type;
+	u32 resolved_type_id = member->type;
+	struct btf_member resolved_member;
+	struct btf *btf = env->btf;
+
+	resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
+	if (!resolved_type) {
+		btf_verifier_log_member(env, struct_type, member,
+					"Invalid member");
+		return -EINVAL;
+	}
+
+	resolved_member = *member;
+	resolved_member.type = resolved_type_id;
+
+	return btf_type_ops(resolved_type)->check_member(env, struct_type,
+							 &resolved_member,
+							 resolved_type);
+}
+
+static int btf_ptr_check_member(struct btf_verifier_env *env,
+				const struct btf_type *struct_type,
+				const struct btf_member *member,
+				const struct btf_type *member_type)
+{
+	u32 struct_size, struct_bits_off, bytes_offset;
+
+	struct_size = struct_type->size;
+	struct_bits_off = member->offset;
+	bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
+
+	if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
+		btf_verifier_log_member(env, struct_type, member,
+					"Member is not byte aligned");
+		return -EINVAL;
+	}
+
+	if (struct_size - bytes_offset < sizeof(void *)) {
+		btf_verifier_log_member(env, struct_type, member,
+					"Member exceeds struct_size");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int btf_ref_type_check_meta(struct btf_verifier_env *env,
+				   const struct btf_type *t,
+				   u32 meta_left)
+{
+	if (btf_type_vlen(t)) {
+		btf_verifier_log_type(env, t, "vlen != 0");
+		return -EINVAL;
+	}
+
+	if (BTF_TYPE_PARENT(t->type)) {
+		btf_verifier_log_type(env, t, "Invalid type_id");
+		return -EINVAL;
+	}
+
+	btf_verifier_log_type(env, t, NULL);
+
+	return 0;
+}
+
+static int btf_modifier_resolve(struct btf_verifier_env *env,
+				const struct resolve_vertex *v)
+{
+	const struct btf_type *t = v->t;
+	const struct btf_type *next_type;
+	u32 next_type_id = t->type;
+	struct btf *btf = env->btf;
+	u32 next_type_size = 0;
+
+	next_type = btf_type_by_id(btf, next_type_id);
+	if (!next_type) {
+		btf_verifier_log_type(env, v->t, "Invalid type_id");
+		return -EINVAL;
+	}
+
+	/* "typedef void new_void", "const void"...etc */
+	if (btf_type_is_void(next_type))
+		goto resolved;
+
+	if (!env_type_is_resolve_sink(env, next_type) &&
+	    !env_type_is_resolved(env, next_type_id))
+		return env_stack_push(env, next_type, next_type_id);
+
+	/* Figure out the resolved next_type_id with size.
+	 * They will be stored in the current modifier's
+	 * resolved_ids and resolved_sizes such that it can
+	 * save us a few type-following when we use it later (e.g. in
+	 * pretty print).
+	 */
+	if (!btf_type_id_size(btf, &next_type_id, &next_type_size) &&
+	    !btf_type_is_void(btf_type_id_resolve(btf, &next_type_id))) {
+		btf_verifier_log_type(env, v->t, "Invalid type_id");
+		return -EINVAL;
+	}
+
+resolved:
+	env_stack_pop_resolved(env, next_type_id, next_type_size);
+
+	return 0;
+}
+
+static int btf_ptr_resolve(struct btf_verifier_env *env,
+			   const struct resolve_vertex *v)
+{
+	const struct btf_type *next_type;
+	const struct btf_type *t = v->t;
+	u32 next_type_id = t->type;
+	struct btf *btf = env->btf;
+	u32 next_type_size = 0;
+
+	next_type = btf_type_by_id(btf, next_type_id);
+	if (!next_type) {
+		btf_verifier_log_type(env, v->t, "Invalid type_id");
+		return -EINVAL;
+	}
+
+	/* "void *" */
+	if (btf_type_is_void(next_type))
+		goto resolved;
+
+	if (!env_type_is_resolve_sink(env, next_type) &&
+	    !env_type_is_resolved(env, next_type_id))
+		return env_stack_push(env, next_type, next_type_id);
+
+	/* If the modifier was RESOLVED during RESOLVE_STRUCT_OR_ARRAY,
+	 * the modifier may have stopped resolving when it was resolved
+	 * to a ptr (last-resolved-ptr).
+	 *
+	 * We now need to continue from the last-resolved-ptr to
+	 * ensure the last-resolved-ptr will not referring back to
+	 * the currenct ptr (t).
+	 */
+	if (btf_type_is_modifier(next_type)) {
+		const struct btf_type *resolved_type;
+		u32 resolved_type_id;
+
+		resolved_type_id = next_type_id;
+		resolved_type = btf_type_id_resolve(btf, &resolved_type_id);
+
+		if (btf_type_is_ptr(resolved_type) &&
+		    !env_type_is_resolve_sink(env, resolved_type) &&
+		    !env_type_is_resolved(env, resolved_type_id))
+			return env_stack_push(env, resolved_type,
+					      resolved_type_id);
+	}
+
+	if (!btf_type_id_size(btf, &next_type_id, &next_type_size) &&
+	    !btf_type_is_void(btf_type_id_resolve(btf, &next_type_id))) {
+		btf_verifier_log_type(env, v->t, "Invalid type_id");
+		return -EINVAL;
+	}
+
+resolved:
+	env_stack_pop_resolved(env, next_type_id, 0);
+
+	return 0;
+}
+
+static void btf_modifier_seq_show(const struct btf *btf,
+				  const struct btf_type *t,
+				  u32 type_id, void *data,
+				  u8 bits_offset, struct seq_file *m)
+{
+	t = btf_type_id_resolve(btf, &type_id);
+
+	btf_type_ops(t)->seq_show(btf, t, type_id, data, bits_offset, m);
+}
+
+static void btf_ptr_seq_show(const struct btf *btf, const struct btf_type *t,
+			     u32 type_id, void *data, u8 bits_offset,
+			     struct seq_file *m)
+{
+	/* It is a hashed value */
+	seq_printf(m, "%p", *(void **)data);
+}
+
+static void btf_ref_type_log(struct btf_verifier_env *env,
+			     const struct btf_type *t)
+{
+	btf_verifier_log(env, "type_id=%u", t->type);
+}
+
+static struct btf_kind_operations modifier_ops = {
+	.check_meta = btf_ref_type_check_meta,
+	.resolve = btf_modifier_resolve,
+	.check_member = btf_modifier_check_member,
+	.log_details = btf_ref_type_log,
+	.seq_show = btf_modifier_seq_show,
+};
+
+static struct btf_kind_operations ptr_ops = {
+	.check_meta = btf_ref_type_check_meta,
+	.resolve = btf_ptr_resolve,
+	.check_member = btf_ptr_check_member,
+	.log_details = btf_ref_type_log,
+	.seq_show = btf_ptr_seq_show,
+};
+
+static struct btf_kind_operations fwd_ops = {
+	.check_meta = btf_ref_type_check_meta,
+	.resolve = btf_df_resolve,
+	.check_member = btf_df_check_member,
+	.log_details = btf_ref_type_log,
+	.seq_show = btf_df_seq_show,
+};
+
+static int btf_array_check_member(struct btf_verifier_env *env,
+				  const struct btf_type *struct_type,
+				  const struct btf_member *member,
+				  const struct btf_type *member_type)
+{
+	u32 struct_bits_off = member->offset;
+	u32 struct_size, bytes_offset;
+	u32 array_type_id, array_size;
+	struct btf *btf = env->btf;
+
+	if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
+		btf_verifier_log_member(env, struct_type, member,
+					"Member is not byte aligned");
+		return -EINVAL;
+	}
+
+	array_type_id = member->type;
+	btf_type_id_size(btf, &array_type_id, &array_size);
+	struct_size = struct_type->size;
+	bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
+	if (struct_size - bytes_offset < array_size) {
+		btf_verifier_log_member(env, struct_type, member,
+					"Member exceeds struct_size");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static s32 btf_array_check_meta(struct btf_verifier_env *env,
+				const struct btf_type *t,
+				u32 meta_left)
+{
+	const struct btf_array *array = btf_type_array(t);
+	u32 meta_needed = sizeof(*array);
+
+	if (meta_left < meta_needed) {
+		btf_verifier_log_basic(env, t,
+				       "meta_left:%u meta_needed:%u",
+				       meta_left, meta_needed);
+		return -EINVAL;
+	}
+
+	if (btf_type_vlen(t)) {
+		btf_verifier_log_type(env, t, "vlen != 0");
+		return -EINVAL;
+	}
+
+	/* We are a little forgiving on array->index_type since
+	 * the kernel is not using it.
+	 */
+	/* Array elem cannot be in type void,
+	 * so !array->type is not allowed.
+	 */
+	if (!array->type || BTF_TYPE_PARENT(array->type)) {
+		btf_verifier_log_type(env, t, "Invalid type_id");
+		return -EINVAL;
+	}
+
+	btf_verifier_log_type(env, t, NULL);
+
+	return meta_needed;
+}
+
+static int btf_array_resolve(struct btf_verifier_env *env,
+			     const struct resolve_vertex *v)
+{
+	const struct btf_array *array = btf_type_array(v->t);
+	const struct btf_type *elem_type;
+	u32 elem_type_id = array->type;
+	struct btf *btf = env->btf;
+	u32 elem_size;
+
+	elem_type = btf_type_by_id(btf, elem_type_id);
+	if (btf_type_is_void_or_null(elem_type)) {
+		btf_verifier_log_type(env, v->t,
+				      "Invalid elem");
+		return -EINVAL;
+	}
+
+	if (!env_type_is_resolve_sink(env, elem_type) &&
+	    !env_type_is_resolved(env, elem_type_id))
+		return env_stack_push(env, elem_type, elem_type_id);
+
+	elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
+	if (!elem_type) {
+		btf_verifier_log_type(env, v->t, "Invalid elem");
+		return -EINVAL;
+	}
+
+	if (btf_type_is_int(elem_type)) {
+		int int_type_data = btf_type_int(elem_type);
+		u16 nr_bits = BTF_INT_BITS(int_type_data);
+		u16 nr_bytes = BITS_ROUNDUP_BYTES(nr_bits);
+
+		/* Put more restriction on array of int.  The int cannot
+		 * be a bit field and it must be either u8/u16/u32/u64.
+		 */
+		if (BITS_PER_BYTE_MASKED(nr_bits) ||
+		    BTF_INT_OFFSET(int_type_data) ||
+		    (nr_bytes != sizeof(u8) && nr_bytes != sizeof(u16) &&
+		     nr_bytes != sizeof(u32) && nr_bytes != sizeof(u64))) {
+			btf_verifier_log_type(env, v->t,
+					      "Invalid array of int");
+			return -EINVAL;
+		}
+	}
+
+	if (array->nelems && elem_size > U32_MAX / array->nelems) {
+		btf_verifier_log_type(env, v->t,
+				      "Array size overflows U32_MAX");
+		return -EINVAL;
+	}
+
+	env_stack_pop_resolved(env, elem_type_id, elem_size * array->nelems);
+
+	return 0;
+}
+
+static void btf_array_log(struct btf_verifier_env *env,
+			  const struct btf_type *t)
+{
+	const struct btf_array *array = btf_type_array(t);
+
+	btf_verifier_log(env, "type_id=%u index_type_id=%u nr_elems=%u",
+			 array->type, array->index_type, array->nelems);
+}
+
+static void btf_array_seq_show(const struct btf *btf, const struct btf_type *t,
+			       u32 type_id, void *data, u8 bits_offset,
+			       struct seq_file *m)
+{
+	const struct btf_array *array = btf_type_array(t);
+	const struct btf_kind_operations *elem_ops;
+	const struct btf_type *elem_type;
+	u32 i, elem_size, elem_type_id;
+
+	elem_type_id = array->type;
+	elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
+	elem_ops = btf_type_ops(elem_type);
+	seq_puts(m, "[");
+	for (i = 0; i < array->nelems; i++) {
+		if (i)
+			seq_puts(m, ",");
+
+		elem_ops->seq_show(btf, elem_type, elem_type_id, data,
+				   bits_offset, m);
+		data += elem_size;
+	}
+	seq_puts(m, "]");
+}
+
+static struct btf_kind_operations array_ops = {
+	.check_meta = btf_array_check_meta,
+	.resolve = btf_array_resolve,
+	.check_member = btf_array_check_member,
+	.log_details = btf_array_log,
+	.seq_show = btf_array_seq_show,
+};
+
+static int btf_struct_check_member(struct btf_verifier_env *env,
+				   const struct btf_type *struct_type,
+				   const struct btf_member *member,
+				   const struct btf_type *member_type)
+{
+	u32 struct_bits_off = member->offset;
+	u32 struct_size, bytes_offset;
+
+	if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
+		btf_verifier_log_member(env, struct_type, member,
+					"Member is not byte aligned");
+		return -EINVAL;
+	}
+
+	struct_size = struct_type->size;
+	bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
+	if (struct_size - bytes_offset < member_type->size) {
+		btf_verifier_log_member(env, struct_type, member,
+					"Member exceeds struct_size");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static s32 btf_struct_check_meta(struct btf_verifier_env *env,
+				 const struct btf_type *t,
+				 u32 meta_left)
+{
+	bool is_union = BTF_INFO_KIND(t->info) == BTF_KIND_UNION;
+	const struct btf_member *member;
+	struct btf *btf = env->btf;
+	u32 struct_size = t->size;
+	u32 meta_needed;
+	u16 i;
+
+	meta_needed = btf_type_vlen(t) * sizeof(*member);
+	if (meta_left < meta_needed) {
+		btf_verifier_log_basic(env, t,
+				       "meta_left:%u meta_needed:%u",
+				       meta_left, meta_needed);
+		return -EINVAL;
+	}
+
+	btf_verifier_log_type(env, t, NULL);
+
+	for_each_member(i, t, member) {
+		if (!btf_name_offset_valid(btf, member->name)) {
+			btf_verifier_log_member(env, t, member,
+						"Invalid member name_offset:%u",
+						member->name);
+			return -EINVAL;
+		}
+
+		/* A member cannot be in type void */
+		if (!member->type || BTF_TYPE_PARENT(member->type)) {
+			btf_verifier_log_member(env, t, member,
+						"Invalid type_id");
+			return -EINVAL;
+		}
+
+		if (is_union && member->offset) {
+			btf_verifier_log_member(env, t, member,
+						"Invalid member bits_offset");
+			return -EINVAL;
+		}
+
+		if (BITS_ROUNDUP_BYTES(member->offset) > struct_size) {
+			btf_verifier_log_member(env, t, member,
+						"Memmber bits_offset exceeds its struct size");
+			return -EINVAL;
+		}
+
+		btf_verifier_log_member(env, t, member, NULL);
+	}
+
+	return meta_needed;
+}
+
+static int btf_struct_resolve(struct btf_verifier_env *env,
+			      const struct resolve_vertex *v)
+{
+	const struct btf_member *member;
+	int err;
+	u16 i;
+
+	/* Before continue resolving the next_member,
+	 * ensure the last member is indeed resolved to a
+	 * type with size info.
+	 */
+	if (v->next_member) {
+		const struct btf_type *last_member_type;
+		const struct btf_member *last_member;
+		u16 last_member_type_id;
+
+		last_member = btf_type_member(v->t) + v->next_member - 1;
+		last_member_type_id = last_member->type;
+		if (WARN_ON_ONCE(!env_type_is_resolved(env,
+						       last_member_type_id)))
+			return -EINVAL;
+
+		last_member_type = btf_type_by_id(env->btf,
+						  last_member_type_id);
+		err = btf_type_ops(last_member_type)->check_member(env, v->t,
+							last_member,
+							last_member_type);
+		if (err)
+			return err;
+	}
+
+	for_each_member_from(i, v->next_member, v->t, member) {
+		u32 member_type_id = member->type;
+		const struct btf_type *member_type = btf_type_by_id(env->btf,
+								member_type_id);
+
+		if (btf_type_is_void_or_null(member_type)) {
+			btf_verifier_log_member(env, v->t, member,
+						"Invalid member");
+			return -EINVAL;
+		}
+
+		if (!env_type_is_resolve_sink(env, member_type) &&
+		    !env_type_is_resolved(env, member_type_id)) {
+			env_stack_set_next_member(env, i + 1);
+			return env_stack_push(env, member_type, member_type_id);
+		}
+
+		err = btf_type_ops(member_type)->check_member(env, v->t,
+							      member,
+							      member_type);
+		if (err)
+			return err;
+	}
+
+	env_stack_pop_resolved(env, 0, 0);
+
+	return 0;
+}
+
+static void btf_struct_log(struct btf_verifier_env *env,
+			   const struct btf_type *t)
+{
+	btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
+}
+
+static void btf_struct_seq_show(const struct btf *btf, const struct btf_type *t,
+				u32 type_id, void *data, u8 bits_offset,
+				struct seq_file *m)
+{
+	const char *seq = BTF_INFO_KIND(t->info) == BTF_KIND_UNION ? "|" : ",";
+	const struct btf_member *member;
+	u32 i;
+
+	seq_puts(m, "{");
+	for_each_member(i, t, member) {
+		const struct btf_type *member_type = btf_type_by_id(btf,
+								member->type);
+		u32 member_offset = member->offset;
+		u32 bytes_offset = BITS_ROUNDDOWN_BYTES(member_offset);
+		u8 bits8_offset = BITS_PER_BYTE_MASKED(member_offset);
+		const struct btf_kind_operations *ops;
+
+		if (i)
+			seq_puts(m, seq);
+
+		ops = btf_type_ops(member_type);
+		ops->seq_show(btf, member_type, member->type,
+			      data + bytes_offset, bits8_offset, m);
+	}
+	seq_puts(m, "}");
+}
+
+static struct btf_kind_operations struct_ops = {
+	.check_meta = btf_struct_check_meta,
+	.resolve = btf_struct_resolve,
+	.check_member = btf_struct_check_member,
+	.log_details = btf_struct_log,
+	.seq_show = btf_struct_seq_show,
+};
+
+static int btf_enum_check_member(struct btf_verifier_env *env,
+				 const struct btf_type *struct_type,
+				 const struct btf_member *member,
+				 const struct btf_type *member_type)
+{
+	u32 struct_bits_off = member->offset;
+	u32 struct_size, bytes_offset;
+
+	if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
+		btf_verifier_log_member(env, struct_type, member,
+					"Member is not byte aligned");
+		return -EINVAL;
+	}
+
+	struct_size = struct_type->size;
+	bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
+	if (struct_size - bytes_offset < sizeof(int)) {
+		btf_verifier_log_member(env, struct_type, member,
+					"Member exceeds struct_size");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static s32 btf_enum_check_meta(struct btf_verifier_env *env,
+			       const struct btf_type *t,
+			       u32 meta_left)
+{
+	const struct btf_enum *enums = btf_type_enum(t);
+	struct btf *btf = env->btf;
+	u16 i, nr_enums;
+	u32 meta_needed;
+
+	nr_enums = btf_type_vlen(t);
+	meta_needed = nr_enums * sizeof(*enums);
+
+	if (meta_left < meta_needed) {
+		btf_verifier_log_basic(env, t,
+				       "meta_left:%u meta_needed:%u",
+				       meta_left, meta_needed);
+		return -EINVAL;
+	}
+
+	if (t->size != sizeof(int)) {
+		btf_verifier_log_type(env, t, "Expected size:%zu",
+				      sizeof(int));
+		return -EINVAL;
+	}
+
+	btf_verifier_log_type(env, t, NULL);
+
+	for (i = 0; i < nr_enums; i++) {
+		if (!btf_name_offset_valid(btf, enums[i].name)) {
+			btf_verifier_log(env, "\tInvalid name_offset:%u",
+					 enums[i].name);
+			return -EINVAL;
+		}
+
+		btf_verifier_log(env, "\t%s val=%d\n",
+				 btf_name_by_offset(btf, enums[i].name),
+				 enums[i].val);
+	}
+
+	return meta_needed;
+}
+
+static void btf_enum_log(struct btf_verifier_env *env,
+			 const struct btf_type *t)
+{
+	btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
+}
+
+static void btf_enum_seq_show(const struct btf *btf, const struct btf_type *t,
+			      u32 type_id, void *data, u8 bits_offset,
+			      struct seq_file *m)
+{
+	const struct btf_enum *enums = btf_type_enum(t);
+	u32 i, nr_enums = btf_type_vlen(t);
+	int v = *(int *)data;
+
+	for (i = 0; i < nr_enums; i++) {
+		if (v == enums[i].val) {
+			seq_printf(m, "%s",
+				   btf_name_by_offset(btf, enums[i].name));
+			return;
+		}
+	}
+
+	seq_printf(m, "%d", v);
+}
+
+static struct btf_kind_operations enum_ops = {
+	.check_meta = btf_enum_check_meta,
+	.resolve = btf_df_resolve,
+	.check_member = btf_enum_check_member,
+	.log_details = btf_enum_log,
+	.seq_show = btf_enum_seq_show,
+};
+
+static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS] = {
+	[BTF_KIND_INT] = &int_ops,
+	[BTF_KIND_PTR] = &ptr_ops,
+	[BTF_KIND_ARRAY] = &array_ops,
+	[BTF_KIND_STRUCT] = &struct_ops,
+	[BTF_KIND_UNION] = &struct_ops,
+	[BTF_KIND_ENUM] = &enum_ops,
+	[BTF_KIND_FWD] = &fwd_ops,
+	[BTF_KIND_TYPEDEF] = &modifier_ops,
+	[BTF_KIND_VOLATILE] = &modifier_ops,
+	[BTF_KIND_CONST] = &modifier_ops,
+	[BTF_KIND_RESTRICT] = &modifier_ops,
+};
+
+static s32 btf_check_meta(struct btf_verifier_env *env,
+			  const struct btf_type *t,
+			  u32 meta_left)
+{
+	u32 saved_meta_left = meta_left;
+	s32 var_meta_size;
+
+	if (meta_left < sizeof(*t)) {
+		btf_verifier_log(env, "[%u] meta_left:%u meta_needed:%zu",
+				 env->log_type_id, meta_left, sizeof(*t));
+		return -EINVAL;
+	}
+	meta_left -= sizeof(*t);
+
+	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",
+				 env->log_type_id, BTF_INFO_KIND(t->info));
+		return -EINVAL;
+	}
+
+	if (!btf_name_offset_valid(env->btf, t->name)) {
+		btf_verifier_log(env, "[%u] Invalid name_offset:%u",
+				 env->log_type_id, t->name);
+		return -EINVAL;
+	}
+
+	var_meta_size = btf_type_ops(t)->check_meta(env, t, meta_left);
+	if (var_meta_size < 0)
+		return var_meta_size;
+
+	meta_left -= var_meta_size;
+
+	return saved_meta_left - meta_left;
+}
+
+static int btf_check_all_metas(struct btf_verifier_env *env)
+{
+	struct btf *btf = env->btf;
+	struct btf_header *hdr;
+	void *cur, *end;
+
+	hdr = btf->hdr;
+	cur = btf->nohdr_data + hdr->type_off;
+	end = btf->nohdr_data + hdr->str_off;
+
+	env->log_type_id = 1;
+	while (cur < end) {
+		struct btf_type *t = cur;
+		s32 meta_size;
+
+		meta_size = btf_check_meta(env, t, end - cur);
+		if (meta_size < 0)
+			return meta_size;
+
+		btf_add_type(env, t);
+		cur += meta_size;
+		env->log_type_id++;
+	}
+
+	return 0;
+}
+
+static int btf_resolve(struct btf_verifier_env *env,
+		       const struct btf_type *t, u32 type_id)
+{
+	const struct resolve_vertex *v;
+	int err = 0;
+
+	env->resolve_mode = RESOLVE_TBD;
+	env_stack_push(env, t, type_id);
+	while (!err && (v = env_stack_peak(env))) {
+		env->log_type_id = v->type_id;
+		err = btf_type_ops(v->t)->resolve(env, v);
+	}
+
+	env->log_type_id = type_id;
+	if (err == -E2BIG)
+		btf_verifier_log_type(env, t,
+				      "Exceeded max resolving depth:%u",
+				      MAX_RESOLVE_DEPTH);
+	else if (err == -EEXIST)
+		btf_verifier_log_type(env, t, "Loop detected");
+
+	return err;
+}
+
+static bool btf_resolve_valid(struct btf_verifier_env *env,
+			      const struct btf_type *t,
+			      u32 type_id)
+{
+	struct btf *btf = env->btf;
+
+	if (!env_type_is_resolved(env, type_id))
+		return false;
+
+	if (btf_type_is_struct(t))
+		return !btf->resolved_ids[type_id] &&
+			!btf->resolved_sizes[type_id];
+
+	if (btf_type_is_modifier(t) || btf_type_is_ptr(t)) {
+		t = btf_type_id_resolve(btf, &type_id);
+		return t && !btf_type_is_modifier(t);
+	}
+
+	if (btf_type_is_array(t)) {
+		const struct btf_array *array = btf_type_array(t);
+		const struct btf_type *elem_type;
+		u32 elem_type_id = array->type;
+		u32 elem_size;
+
+		elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
+		return elem_type && !btf_type_is_modifier(elem_type) &&
+			(array->nelems * elem_size ==
+			 btf->resolved_sizes[type_id]);
+	}
+
+	return false;
+}
+
+static int btf_check_all_types(struct btf_verifier_env *env)
+{
+	struct btf *btf = env->btf;
+	u32 type_id;
+	int err;
+
+	err = env_resolve_init(env);
+	if (err)
+		return err;
+
+	env->phase++;
+	for (type_id = 1; type_id <= btf->nr_types; type_id++) {
+		const struct btf_type *t = btf_type_by_id(btf, type_id);
+
+		env->log_type_id = type_id;
+		if (btf_type_needs_resolve(t) &&
+		    !env_type_is_resolved(env, type_id)) {
+			err = btf_resolve(env, t, type_id);
+			if (err)
+				return err;
+		}
+
+		if (btf_type_needs_resolve(t) &&
+		    !btf_resolve_valid(env, t, type_id)) {
+			btf_verifier_log_type(env, t, "Invalid resolve state");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static int btf_parse_type_sec(struct btf_verifier_env *env)
+{
+	int err;
+
+	err = btf_check_all_metas(env);
+	if (err)
+		return err;
+
+	return btf_check_all_types(env);
+}
+
+static int btf_parse_str_sec(struct btf_verifier_env *env)
+{
+	const struct btf_header *hdr;
+	struct btf *btf = env->btf;
+	const char *start, *end;
+
+	hdr = btf->hdr;
+	start = btf->nohdr_data + hdr->str_off;
+	end = start + hdr->str_len;
+
+	if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_NAME_OFFSET ||
+	    start[0] || end[-1]) {
+		btf_verifier_log(env, "Invalid string section");
+		return -EINVAL;
+	}
+
+	btf->strings = start;
+
+	return 0;
+}
+
+static int btf_parse_hdr(struct btf_verifier_env *env)
+{
+	const struct btf_header *hdr;
+	struct btf *btf = env->btf;
+	u32 meta_left;
+
+	if (btf->data_size < sizeof(*hdr)) {
+		btf_verifier_log(env, "btf_header not found");
+		return -EINVAL;
+	}
+
+	btf_verifier_log_hdr(env);
+
+	hdr = btf->hdr;
+	if (hdr->magic != BTF_MAGIC) {
+		btf_verifier_log(env, "Invalid magic");
+		return -EINVAL;
+	}
+
+	if (hdr->version != BTF_VERSION) {
+		btf_verifier_log(env, "Unsupported version");
+		return -ENOTSUPP;
+	}
+
+	if (hdr->flags) {
+		btf_verifier_log(env, "Unsupported flags");
+		return -ENOTSUPP;
+	}
+
+	meta_left = btf->data_size - sizeof(*hdr);
+	if (!meta_left) {
+		btf_verifier_log(env, "No data");
+		return -EINVAL;
+	}
+
+	if (meta_left < hdr->type_off || hdr->str_off <= hdr->type_off ||
+	    /* Type section must align to 4 bytes */
+	    hdr->type_off & (sizeof(u32) - 1)) {
+		btf_verifier_log(env, "Invalid type_off");
+		return -EINVAL;
+	}
+
+	if (meta_left < hdr->str_off ||
+	    meta_left - hdr->str_off < hdr->str_len) {
+		btf_verifier_log(env, "Invalid str_off or str_len");
+		return -EINVAL;
+	}
+
+	btf->nohdr_data = btf->hdr + 1;
+
+	return 0;
+}
+
+static struct btf *btf_parse(void __user *btf_data, u32 btf_data_size,
+			     u32 log_level, char __user *log_ubuf, u32 log_size)
+{
+	struct btf_verifier_env *env = NULL;
+	struct bpf_verifier_log *log;
+	struct btf *btf = NULL;
+	u8 *data;
+	int err;
+
+	if (btf_data_size > BTF_MAX_SIZE)
+		return ERR_PTR(-E2BIG);
+
+	env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
+	if (!env)
+		return ERR_PTR(-ENOMEM);
+
+	log = &env->log;
+	if (log_level || log_ubuf || log_size) {
+		/* user requested verbose verifier output
+		 * and supplied buffer to store the verification trace
+		 */
+		log->level = log_level;
+		log->ubuf = log_ubuf;
+		log->len_total = log_size;
+
+		/* log attributes have to be sane */
+		if (log->len_total < 128 || log->len_total > UINT_MAX >> 8 ||
+		    !log->level || !log->ubuf) {
+			err = -EINVAL;
+			goto errout;
+		}
+	}
+
+	btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
+	if (!btf) {
+		err = -ENOMEM;
+		goto errout;
+	}
+
+	data = kvmalloc(btf_data_size, GFP_KERNEL | __GFP_NOWARN);
+	if (!data) {
+		err = -ENOMEM;
+		goto errout;
+	}
+
+	btf->data = data;
+	btf->data_size = btf_data_size;
+
+	if (copy_from_user(data, btf_data, btf_data_size)) {
+		err = -EFAULT;
+		goto errout;
+	}
+
+	env->btf = btf;
+
+	err = btf_parse_hdr(env);
+	if (err)
+		goto errout;
+
+	err = btf_parse_str_sec(env);
+	if (err)
+		goto errout;
+
+	err = btf_parse_type_sec(env);
+	if (err)
+		goto errout;
+
+	if (!err && log->level && bpf_verifier_log_full(log)) {
+		err = -ENOSPC;
+		goto errout;
+	}
+
+	if (!err) {
+		btf_verifier_env_free(env);
+		btf_get(btf);
+		return btf;
+	}
+
+errout:
+	btf_verifier_env_free(env);
+	if (btf)
+		btf_free(btf);
+	return ERR_PTR(err);
+}
+
+void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
+		       struct seq_file *m)
+{
+	const struct btf_type *t = btf_type_by_id(btf, type_id);
+
+	btf_type_ops(t)->seq_show(btf, t, type_id, obj, 0, m);
+}
+
+static int btf_release(struct inode *inode, struct file *filp)
+{
+	btf_put(filp->private_data);
+	return 0;
+}
+
+const struct file_operations btf_fops = {
+	.release	= btf_release,
+};
+
+int btf_new_fd(const union bpf_attr *attr)
+{
+	struct btf *btf;
+	int fd;
+
+	btf = btf_parse(u64_to_user_ptr(attr->btf),
+			attr->btf_size, attr->btf_log_level,
+			u64_to_user_ptr(attr->btf_log_buf),
+			attr->btf_log_size);
+	if (IS_ERR(btf))
+		return PTR_ERR(btf);
+
+	fd = anon_inode_getfd("btf", &btf_fops, btf,
+			      O_RDONLY | O_CLOEXEC);
+	if (fd < 0)
+		btf_put(btf);
+
+	return fd;
+}
+
+struct btf *btf_get_by_fd(int fd)
+{
+	struct btf *btf;
+	struct fd f;
+
+	f = fdget(fd);
+
+	if (!f.file)
+		return ERR_PTR(-EBADF);
+
+	if (f.file->f_op != &btf_fops) {
+		fdput(f);
+		return ERR_PTR(-EINVAL);
+	}
+
+	btf = f.file->private_data;
+	btf_get(btf);
+	fdput(f);
+
+	return btf;
+}
+
+int btf_get_info_by_fd(const struct btf *btf,
+		       const union bpf_attr *attr,
+		       union bpf_attr __user *uattr)
+{
+	void __user *udata = u64_to_user_ptr(attr->info.info);
+	u32 copy_len = min_t(u32, btf->data_size,
+			     attr->info.info_len);
+
+	if (copy_to_user(udata, btf->data, copy_len) ||
+	    put_user(btf->data_size, &uattr->info.info_len))
+		return -EFAULT;
+
+	return 0;
+}

kernel/bpf/inode.c

@@ -150,8 +150,154 @@ static int bpf_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 	return 0;
 }
 
+struct map_iter {
+	void *key;
+	bool done;
+};
+
+static struct map_iter *map_iter(struct seq_file *m)
+{
+	return m->private;
+}
+
+static struct bpf_map *seq_file_to_map(struct seq_file *m)
+{
+	return file_inode(m->file)->i_private;
+}
+
+static void map_iter_free(struct map_iter *iter)
+{
+	if (iter) {
+		kfree(iter->key);
+		kfree(iter);
+	}
+}
+
+static struct map_iter *map_iter_alloc(struct bpf_map *map)
+{
+	struct map_iter *iter;
+
+	iter = kzalloc(sizeof(*iter), GFP_KERNEL | __GFP_NOWARN);
+	if (!iter)
+		goto error;
+
+	iter->key = kzalloc(map->key_size, GFP_KERNEL | __GFP_NOWARN);
+	if (!iter->key)
+		goto error;
+
+	return iter;
+
+error:
+	map_iter_free(iter);
+	return NULL;
+}
+
+static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct bpf_map *map = seq_file_to_map(m);
+	void *key = map_iter(m)->key;
+
+	if (map_iter(m)->done)
+		return NULL;
+
+	if (unlikely(v == SEQ_START_TOKEN))
+		goto done;
+
+	if (map->ops->map_get_next_key(map, key, key)) {
+		map_iter(m)->done = true;
+		return NULL;
+	}
+
+done:
+	++(*pos);
+	return key;
+}
+
+static void *map_seq_start(struct seq_file *m, loff_t *pos)
+{
+	if (map_iter(m)->done)
+		return NULL;
+
+	return *pos ? map_iter(m)->key : SEQ_START_TOKEN;
+}
+
+static void map_seq_stop(struct seq_file *m, void *v)
+{
+}
+
+static int map_seq_show(struct seq_file *m, void *v)
+{
+	struct bpf_map *map = seq_file_to_map(m);
+	void *key = map_iter(m)->key;
+
+	if (unlikely(v == SEQ_START_TOKEN)) {
+		seq_puts(m, "# WARNING!! The output is for debug purpose only\n");
+		seq_puts(m, "# WARNING!! The output format will change\n");
+	} else {
+		map->ops->map_seq_show_elem(map, key, m);
+	}
+
+	return 0;
+}
+
+static const struct seq_operations bpffs_map_seq_ops = {
+	.start	= map_seq_start,
+	.next	= map_seq_next,
+	.show	= map_seq_show,
+	.stop	= map_seq_stop,
+};
+
+static int bpffs_map_open(struct inode *inode, struct file *file)
+{
+	struct bpf_map *map = inode->i_private;
+	struct map_iter *iter;
+	struct seq_file *m;
+	int err;
+
+	iter = map_iter_alloc(map);
+	if (!iter)
+		return -ENOMEM;
+
+	err = seq_open(file, &bpffs_map_seq_ops);
+	if (err) {
+		map_iter_free(iter);
+		return err;
+	}
+
+	m = file->private_data;
+	m->private = iter;
+
+	return 0;
+}
+
+static int bpffs_map_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *m = file->private_data;
+
+	map_iter_free(map_iter(m));
+
+	return seq_release(inode, file);
+}
+
+/* bpffs_map_fops should only implement the basic
+ * read operation for a BPF map.  The purpose is to
+ * provide a simple user intuitive way to do
+ * "cat bpffs/pathto/a-pinned-map".
+ *
+ * Other operations (e.g. write, lookup...) should be realized by
+ * the userspace tools (e.g. bpftool) through the
+ * BPF_OBJ_GET_INFO_BY_FD and the map's lookup/update
+ * interface.
+ */
+static const struct file_operations bpffs_map_fops = {
+	.open		= bpffs_map_open,
+	.read		= seq_read,
+	.release	= bpffs_map_release,
+};
+
 static int bpf_mkobj_ops(struct dentry *dentry, umode_t mode, void *raw,
-			 const struct inode_operations *iops)
+			 const struct inode_operations *iops,
+			 const struct file_operations *fops)
 {
 	struct inode *dir = dentry->d_parent->d_inode;
 	struct inode *inode = bpf_get_inode(dir->i_sb, dir, mode);
@@ -159,6 +305,7 @@ static int bpf_mkobj_ops(struct dentry *dentry, umode_t mode, void *raw,
 		return PTR_ERR(inode);
 
 	inode->i_op = iops;
+	inode->i_fop = fops;
 	inode->i_private = raw;
 
 	bpf_dentry_finalize(dentry, inode, dir);
@@ -167,12 +314,15 @@ static int bpf_mkobj_ops(struct dentry *dentry, umode_t mode, void *raw,
 
 static int bpf_mkprog(struct dentry *dentry, umode_t mode, void *arg)
 {
-	return bpf_mkobj_ops(dentry, mode, arg, &bpf_prog_iops);
+	return bpf_mkobj_ops(dentry, mode, arg, &bpf_prog_iops, NULL);
 }
 
 static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg)
 {
-	return bpf_mkobj_ops(dentry, mode, arg, &bpf_map_iops);
+	struct bpf_map *map = arg;
+
+	return bpf_mkobj_ops(dentry, mode, arg, &bpf_map_iops,
+			     map->btf ? &bpffs_map_fops : NULL);
 }
 
 static struct dentry *

kernel/bpf/syscall.c

@@ -11,6 +11,7 @@
  */
 #include <linux/bpf.h>
 #include <linux/bpf_trace.h>
+#include <linux/btf.h>
 #include <linux/syscalls.h>
 #include <linux/slab.h>
 #include <linux/sched/signal.h>
@@ -26,6 +27,7 @@
 #include <linux/cred.h>
 #include <linux/timekeeping.h>
 #include <linux/ctype.h>
+#include <linux/btf.h>
 
 #define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PROG_ARRAY || \
 			   (map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \
@@ -250,6 +252,7 @@ static void bpf_map_free_deferred(struct work_struct *work)
 
 	bpf_map_uncharge_memlock(map);
 	security_bpf_map_free(map);
+	btf_put(map->btf);
 	/* implementation dependent freeing */
 	map->ops->map_free(map);
 }
@@ -415,7 +418,7 @@ static int bpf_obj_name_cpy(char *dst, const char *src)
 	return 0;
 }
 
-#define BPF_MAP_CREATE_LAST_FIELD map_ifindex
+#define BPF_MAP_CREATE_LAST_FIELD btf_value_id
 /* called via syscall */
 static int map_create(union bpf_attr *attr)
 {
@@ -449,6 +452,33 @@ static int map_create(union bpf_attr *attr)
 	atomic_set(&map->refcnt, 1);
 	atomic_set(&map->usercnt, 1);
 
+	if (bpf_map_support_seq_show(map) &&
+	    (attr->btf_key_id || attr->btf_value_id)) {
+		struct btf *btf;
+
+		if (!attr->btf_key_id || !attr->btf_value_id) {
+			err = -EINVAL;
+			goto free_map_nouncharge;
+		}
+
+		btf = btf_get_by_fd(attr->btf_fd);
+		if (IS_ERR(btf)) {
+			err = PTR_ERR(btf);
+			goto free_map_nouncharge;
+		}
+
+		err = map->ops->map_check_btf(map, btf, attr->btf_key_id,
+					      attr->btf_value_id);
+		if (err) {
+			btf_put(btf);
+			goto free_map_nouncharge;
+		}
+
+		map->btf = btf;
+		map->btf_key_id = attr->btf_key_id;
+		map->btf_value_id = attr->btf_value_id;
+	}
+
 	err = security_bpf_map_alloc(map);
 	if (err)
 		goto free_map_nouncharge;
@@ -481,6 +511,7 @@ static int map_create(union bpf_attr *attr)
 free_map_sec:
 	security_bpf_map_free(map);
 free_map_nouncharge:
+	btf_put(map->btf);
 	map->ops->map_free(map);
 	return err;
 }
@@ -2016,6 +2047,8 @@ static int bpf_obj_get_info_by_fd(const union bpf_attr *attr,
 	else if (f.file->f_op == &bpf_map_fops)
 		err = bpf_map_get_info_by_fd(f.file->private_data, attr,
 					     uattr);
+	else if (f.file->f_op == &btf_fops)
+		err = btf_get_info_by_fd(f.file->private_data, attr, uattr);
 	else
 		err = -EINVAL;
 
@@ -2023,6 +2056,19 @@ static int bpf_obj_get_info_by_fd(const union bpf_attr *attr,
 	return err;
 }
 
+#define BPF_BTF_LOAD_LAST_FIELD btf_log_level
+
+static int bpf_btf_load(const union bpf_attr *attr)
+{
+	if (CHECK_ATTR(BPF_BTF_LOAD))
+		return -EINVAL;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	return btf_new_fd(attr);
+}
+
 SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
 {
 	union bpf_attr attr = {};
@@ -2103,6 +2149,9 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
 	case BPF_RAW_TRACEPOINT_OPEN:
 		err = bpf_raw_tracepoint_open(&attr);
 		break;
+	case BPF_BTF_LOAD:
+		err = bpf_btf_load(&attr);
+		break;
 	default:
 		err = -EINVAL;
 		break;

tools/include/uapi/linux/bpf.h

@@ -95,6 +95,7 @@ enum bpf_cmd {
 	BPF_OBJ_GET_INFO_BY_FD,
 	BPF_PROG_QUERY,
 	BPF_RAW_TRACEPOINT_OPEN,
+	BPF_BTF_LOAD,
 };
 
 enum bpf_map_type {
@@ -279,6 +280,9 @@ union bpf_attr {
 					 */
 		char	map_name[BPF_OBJ_NAME_LEN];
 		__u32	map_ifindex;	/* ifindex of netdev to create on */
+		__u32	btf_fd;		/* fd pointing to a BTF type data */
+		__u32	btf_key_id;	/* BTF type_id of the key */
+		__u32	btf_value_id;	/* BTF type_id of the value */
 	};
 
 	struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
@@ -363,6 +367,14 @@ union bpf_attr {
 		__u64 name;
 		__u32 prog_fd;
 	} raw_tracepoint;
+
+	struct { /* anonymous struct for BPF_BTF_LOAD */
+		__aligned_u64	btf;
+		__aligned_u64	btf_log_buf;
+		__u32		btf_size;
+		__u32		btf_log_size;
+		__u32		btf_log_level;
+	};
 } __attribute__((aligned(8)));
 
 /* BPF helper function descriptions:

tools/include/uapi/linux/btf.h

+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* Copyright (c) 2018 Facebook */
+#ifndef _UAPI__LINUX_BTF_H__
+#define _UAPI__LINUX_BTF_H__
+
+#include <linux/types.h>
+
+#define BTF_MAGIC	0xeB9F
+#define BTF_MAGIC_SWAP	0x9FeB
+#define BTF_VERSION	1
+#define BTF_FLAGS_COMPR	0x01
+
+struct btf_header {
+	__u16	magic;
+	__u8	version;
+	__u8	flags;
+
+	__u32	parent_label;
+	__u32	parent_name;
+
+	/* All offsets are in bytes relative to the end of this header */
+	__u32	label_off;	/* offset of label section	*/
+	__u32	object_off;	/* offset of data object section*/
+	__u32	func_off;	/* offset of function section	*/
+	__u32	type_off;	/* offset of type section	*/
+	__u32	str_off;	/* offset of string section	*/
+	__u32	str_len;	/* length of string section	*/
+};
+
+/* Max # of type identifier */
+#define BTF_MAX_TYPE	0x7fffffff
+/* Max offset into the string section */
+#define BTF_MAX_NAME_OFFSET	0x7fffffff
+/* Max # of struct/union/enum members or func args */
+#define BTF_MAX_VLEN	0xffff
+
+/* The type id is referring to a parent BTF */
+#define BTF_TYPE_PARENT(id)	(((id) >> 31) & 0x1)
+#define BTF_TYPE_ID(id)		((id) & BTF_MAX_TYPE)
+
+/* String is in the ELF string section */
+#define BTF_STR_TBL_ELF_ID(ref)	(((ref) >> 31) & 0x1)
+#define BTF_STR_OFFSET(ref)	((ref) & BTF_MAX_NAME_OFFSET)
+
+struct btf_type {
+	__u32 name;
+	/* "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    31: root
+	 */
+	__u32 info;
+	/* "size" is used by INT, ENUM, STRUCT and UNION.
+	 * "size" tells the size of the type it is describing.
+	 *
+	 * "type" is used by PTR, TYPEDEF, VOLATILE, CONST and RESTRICT.
+	 * "type" is a type_id referring to another type.
+	 */
+	union {
+		__u32 size;
+		__u32 type;
+	};
+};
+
+#define BTF_INFO_KIND(info)	(((info) >> 24) & 0x1f)
+#define BTF_INFO_ISROOT(info)	(!!(((info) >> 24) & 0x80))
+#define BTF_INFO_VLEN(info)	((info) & 0xffff)
+
+#define BTF_KIND_UNKN		0	/* Unknown	*/
+#define BTF_KIND_INT		1	/* Integer	*/
+#define BTF_KIND_PTR		2	/* Pointer	*/
+#define BTF_KIND_ARRAY		3	/* Array	*/
+#define BTF_KIND_STRUCT		4	/* Struct	*/
+#define BTF_KIND_UNION		5	/* Union	*/
+#define BTF_KIND_ENUM		6	/* Enumeration	*/
+#define BTF_KIND_FWD		7	/* Forward	*/
+#define BTF_KIND_TYPEDEF	8	/* Typedef	*/
+#define BTF_KIND_VOLATILE	9	/* Volatile	*/
+#define BTF_KIND_CONST		10	/* Const	*/
+#define BTF_KIND_RESTRICT	11	/* Restrict	*/
+#define BTF_KIND_MAX		11
+#define NR_BTF_KINDS		12
+
+/* For some specific BTF_KIND, "struct btf_type" is immediately
+ * followed by extra data.
+ */
+
+/* BTF_KIND_INT is followed by a u32 and the following
+ * is the 32 bits arrangement:
+ */
+#define BTF_INT_ENCODING(VAL)	(((VAL) & 0xff000000) >> 24)
+#define BTF_INT_OFFSET(VAL)	(((VAL  & 0x00ff0000)) >> 16)
+#define BTF_INT_BITS(VAL)	((VAL)  & 0x0000ffff)
+
+/* Attributes stored in the BTF_INT_ENCODING */
+#define BTF_INT_SIGNED	0x1
+#define BTF_INT_CHAR	0x2
+#define BTF_INT_BOOL	0x4
+#define BTF_INT_VARARGS	0x8
+
+/* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
+ * The exact number of btf_enum is stored in the vlen (of the
+ * info in "struct btf_type").
+ */
+struct btf_enum {
+	__u32	name;
+	__s32	val;
+};
+
+/* BTF_KIND_ARRAY is followed by one "struct btf_array" */
+struct btf_array {
+	__u32	type;
+	__u32	index_type;
+	__u32	nelems;
+};
+
+/* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
+ * by multiple "struct btf_member".  The exact number
+ * of btf_member is stored in the vlen (of the info in
+ * "struct btf_type").
+ */
+struct btf_member {
+	__u32	name;
+	__u32	type;
+	__u32	offset;	/* offset in bits */
+};
+
+#endif /* _UAPI__LINUX_BTF_H__ */

tools/lib/bpf/Build

-libbpf-y := libbpf.o bpf.o nlattr.o
+libbpf-y := libbpf.o bpf.o nlattr.o btf.o

tools/lib/bpf/bpf.c

@@ -73,43 +73,76 @@ static inline int sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr,
 	return syscall(__NR_bpf, cmd, attr, size);
 }
 
-int bpf_create_map_node(enum bpf_map_type map_type, const char *name,
-			int key_size, int value_size, int max_entries,
-			__u32 map_flags, int node)
+int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr)
 {
-	__u32 name_len = name ? strlen(name) : 0;
+	__u32 name_len = create_attr->name ? strlen(create_attr->name) : 0;
 	union bpf_attr attr;
 
 	memset(&attr, '\0', sizeof(attr));
 
-	attr.map_type = map_type;
-	attr.key_size = key_size;
-	attr.value_size = value_size;
-	attr.max_entries = max_entries;
-	attr.map_flags = map_flags;
-	memcpy(attr.map_name, name, min(name_len, BPF_OBJ_NAME_LEN - 1));
+	attr.map_type = create_attr->map_type;
+	attr.key_size = create_attr->key_size;
+	attr.value_size = create_attr->value_size;
+	attr.max_entries = create_attr->max_entries;
+	attr.map_flags = create_attr->map_flags;
+	memcpy(attr.map_name, create_attr->name,
+	       min(name_len, BPF_OBJ_NAME_LEN - 1));
+	attr.numa_node = create_attr->numa_node;
+	attr.btf_fd = create_attr->btf_fd;
+	attr.btf_key_id = create_attr->btf_key_id;
+	attr.btf_value_id = create_attr->btf_value_id;
+
+	return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
+}
 
+int bpf_create_map_node(enum bpf_map_type map_type, const char *name,
+			int key_size, int value_size, int max_entries,
+			__u32 map_flags, int node)
+{
+	struct bpf_create_map_attr map_attr = {};
+
+	map_attr.name = name;
+	map_attr.map_type = map_type;
+	map_attr.map_flags = map_flags;
+	map_attr.key_size = key_size;
+	map_attr.value_size = value_size;
+	map_attr.max_entries = max_entries;
 	if (node >= 0) {
-		attr.map_flags |= BPF_F_NUMA_NODE;
-		attr.numa_node = node;
+		map_attr.numa_node = node;
+		map_attr.map_flags |= BPF_F_NUMA_NODE;
 	}
 
-	return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
+	return bpf_create_map_xattr(&map_attr);
 }
 
 int bpf_create_map(enum bpf_map_type map_type, int key_size,
 		   int value_size, int max_entries, __u32 map_flags)
 {
-	return bpf_create_map_node(map_type, NULL, key_size, value_size,
-				   max_entries, map_flags, -1);
+	struct bpf_create_map_attr map_attr = {};
+
+	map_attr.map_type = map_type;
+	map_attr.map_flags = map_flags;
+	map_attr.key_size = key_size;
+	map_attr.value_size = value_size;
+	map_attr.max_entries = max_entries;
+
+	return bpf_create_map_xattr(&map_attr);
 }
 
 int bpf_create_map_name(enum bpf_map_type map_type, const char *name,
 			int key_size, int value_size, int max_entries,
 			__u32 map_flags)
 {
-	return bpf_create_map_node(map_type, name, key_size, value_size,
-				   max_entries, map_flags, -1);
+	struct bpf_create_map_attr map_attr = {};
+
+	map_attr.name = name;
+	map_attr.map_type = map_type;
+	map_attr.map_flags = map_flags;
+	map_attr.key_size = key_size;
+	map_attr.value_size = value_size;
+	map_attr.max_entries = max_entries;
+
+	return bpf_create_map_xattr(&map_attr);
 }
 
 int bpf_create_map_in_map_node(enum bpf_map_type map_type, const char *name,
@@ -573,3 +606,28 @@ int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)
 	close(sock);
 	return ret;
 }
+
+int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf, __u32 log_buf_size,
+		 bool do_log)
+{
+	union bpf_attr attr = {};
+	int fd;
+
+	attr.btf = ptr_to_u64(btf);
+	attr.btf_size = btf_size;
+
+retry:
+	if (do_log && log_buf && log_buf_size) {
+		attr.btf_log_level = 1;
+		attr.btf_log_size = log_buf_size;
+		attr.btf_log_buf = ptr_to_u64(log_buf);
+	}
+
+	fd = sys_bpf(BPF_BTF_LOAD, &attr, sizeof(attr));
+	if (fd == -1 && !do_log && log_buf && log_buf_size) {
+		do_log = true;
+		goto retry;
+	}
+
+	return fd;
+}

tools/lib/bpf/bpf.h

@@ -26,6 +26,20 @@
 #include <linux/bpf.h>
 #include <stddef.h>
 
+struct bpf_create_map_attr {
+	const char *name;
+	enum bpf_map_type map_type;
+	__u32 map_flags;
+	__u32 key_size;
+	__u32 value_size;
+	__u32 max_entries;
+	__u32 numa_node;
+	__u32 btf_fd;
+	__u32 btf_key_id;
+	__u32 btf_value_id;
+};
+
+int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr);
 int bpf_create_map_node(enum bpf_map_type map_type, const char *name,
 			int key_size, int value_size, int max_entries,
 			__u32 map_flags, int node);
@@ -87,4 +101,6 @@ int bpf_obj_get_info_by_fd(int prog_fd, void *info, __u32 *info_len);
 int bpf_prog_query(int target_fd, enum bpf_attach_type type, __u32 query_flags,
 		   __u32 *attach_flags, __u32 *prog_ids, __u32 *prog_cnt);
 int bpf_raw_tracepoint_open(const char *name, int prog_fd);
+int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf, __u32 log_buf_size,
+		 bool do_log);
 #endif

tools/lib/bpf/btf.c

+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2018 Facebook */
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <linux/err.h>
+#include <linux/btf.h>
+#include "btf.h"
+#include "bpf.h"
+
+#define elog(fmt, ...) { if (err_log) err_log(fmt, ##__VA_ARGS__); }
+#define max(a, b) ((a) > (b) ? (a) : (b))
+#define min(a, b) ((a) < (b) ? (a) : (b))
+
+#define BTF_MAX_NR_TYPES 65535
+
+static struct btf_type btf_void;
+
+struct btf {
+	union {
+		struct btf_header *hdr;
+		void *data;
+	};
+	struct btf_type **types;
+	const char *strings;
+	void *nohdr_data;
+	uint32_t nr_types;
+	uint32_t types_size;
+	uint32_t data_size;
+	int fd;
+};
+
+static const char *btf_name_by_offset(const struct btf *btf, uint32_t offset)
+{
+	if (!BTF_STR_TBL_ELF_ID(offset) &&
+	    BTF_STR_OFFSET(offset) < btf->hdr->str_len)
+		return &btf->strings[BTF_STR_OFFSET(offset)];
+	else
+		return NULL;
+}
+
+static int btf_add_type(struct btf *btf, struct btf_type *t)
+{
+	if (btf->types_size - btf->nr_types < 2) {
+		struct btf_type **new_types;
+		u32 expand_by, new_size;
+
+		if (btf->types_size == BTF_MAX_NR_TYPES)
+			return -E2BIG;
+
+		expand_by = max(btf->types_size >> 2, 16);
+		new_size = min(BTF_MAX_NR_TYPES, btf->types_size + expand_by);
+
+		new_types = realloc(btf->types, sizeof(*new_types) * new_size);
+		if (!new_types)
+			return -ENOMEM;
+
+		if (btf->nr_types == 0)
+			new_types[0] = &btf_void;
+
+		btf->types = new_types;
+		btf->types_size = new_size;
+	}
+
+	btf->types[++(btf->nr_types)] = t;
+
+	return 0;
+}
+
+static int btf_parse_hdr(struct btf *btf, btf_print_fn_t err_log)
+{
+	const struct btf_header *hdr = btf->hdr;
+	u32 meta_left;
+
+	if (btf->data_size < sizeof(struct btf_header)) {
+		elog("BTF header not found\n");
+		return -EINVAL;
+	}
+
+	if (hdr->magic != BTF_MAGIC) {
+		elog("Invalid BTF magic:%x\n", hdr->magic);
+		return -EINVAL;
+	}
+
+	if (hdr->version != BTF_VERSION) {
+		elog("Unsupported BTF version:%u\n", hdr->version);
+		return -ENOTSUP;
+	}
+
+	if (hdr->flags) {
+		elog("Unsupported BTF flags:%x\n", hdr->flags);
+		return -ENOTSUP;
+	}
+
+	meta_left = btf->data_size - sizeof(*hdr);
+	if (!meta_left) {
+		elog("BTF has no data\n");
+		return -EINVAL;
+	}
+
+	if (meta_left < hdr->type_off) {
+		elog("Invalid BTF type section offset:%u\n", hdr->type_off);
+		return -EINVAL;
+	}
+
+	if (meta_left < hdr->str_off) {
+		elog("Invalid BTF string section offset:%u\n", hdr->str_off);
+		return -EINVAL;
+	}
+
+	if (hdr->type_off >= hdr->str_off) {
+		elog("BTF type section offset >= string section offset. No type?\n");
+		return -EINVAL;
+	}
+
+	if (hdr->type_off & 0x02) {
+		elog("BTF type section is not aligned to 4 bytes\n");
+		return -EINVAL;
+	}
+
+	btf->nohdr_data = btf->hdr + 1;
+
+	return 0;
+}
+
+static int btf_parse_str_sec(struct btf *btf, btf_print_fn_t err_log)
+{
+	const struct btf_header *hdr = btf->hdr;
+	const char *start = btf->nohdr_data + hdr->str_off;
+	const char *end = start + btf->hdr->str_len;
+
+	if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_NAME_OFFSET ||
+	    start[0] || end[-1]) {
+		elog("Invalid BTF string section\n");
+		return -EINVAL;
+	}
+
+	btf->strings = start;
+
+	return 0;
+}
+
+static int btf_parse_type_sec(struct btf *btf, btf_print_fn_t err_log)
+{
+	struct btf_header *hdr = btf->hdr;
+	void *nohdr_data = btf->nohdr_data;
+	void *next_type = nohdr_data + hdr->type_off;
+	void *end_type = nohdr_data + hdr->str_off;
+
+	while (next_type < end_type) {
+		struct btf_type *t = next_type;
+		uint16_t vlen = BTF_INFO_VLEN(t->info);
+		int err;
+
+		next_type += sizeof(*t);
+		switch (BTF_INFO_KIND(t->info)) {
+		case BTF_KIND_INT:
+			next_type += sizeof(int);
+			break;
+		case BTF_KIND_ARRAY:
+			next_type += sizeof(struct btf_array);
+			break;
+		case BTF_KIND_STRUCT:
+		case BTF_KIND_UNION:
+			next_type += vlen * sizeof(struct btf_member);
+			break;
+		case BTF_KIND_ENUM:
+			next_type += vlen * sizeof(struct btf_enum);
+			break;
+		case BTF_KIND_TYPEDEF:
+		case BTF_KIND_PTR:
+		case BTF_KIND_FWD:
+		case BTF_KIND_VOLATILE:
+		case BTF_KIND_CONST:
+		case BTF_KIND_RESTRICT:
+			break;
+		default:
+			elog("Unsupported BTF_KIND:%u\n",
+			     BTF_INFO_KIND(t->info));
+			return -EINVAL;
+		}
+
+		err = btf_add_type(btf, t);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static const struct btf_type *btf_type_by_id(const struct btf *btf,
+					     uint32_t type_id)
+{
+	if (type_id > btf->nr_types)
+		return NULL;
+
+	return btf->types[type_id];
+}
+
+static bool btf_type_is_void(const struct btf_type *t)
+{
+	return t == &btf_void || BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
+}
+
+static bool btf_type_is_void_or_null(const struct btf_type *t)
+{
+	return !t || btf_type_is_void(t);
+}
+
+static int64_t btf_type_size(const struct btf_type *t)
+{
+	switch (BTF_INFO_KIND(t->info)) {
+	case BTF_KIND_INT:
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+	case BTF_KIND_ENUM:
+		return t->size;
+	case BTF_KIND_PTR:
+		return sizeof(void *);
+	default:
+		return -EINVAL;
+	}
+}
+
+#define MAX_RESOLVE_DEPTH 32
+
+int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id)
+{
+	const struct btf_array *array;
+	const struct btf_type *t;
+	uint32_t nelems = 1;
+	int64_t size = -1;
+	int i;
+
+	t = btf_type_by_id(btf, type_id);
+	for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t);
+	     i++) {
+		size = btf_type_size(t);
+		if (size >= 0)
+			break;
+
+		switch (BTF_INFO_KIND(t->info)) {
+		case BTF_KIND_TYPEDEF:
+		case BTF_KIND_VOLATILE:
+		case BTF_KIND_CONST:
+		case BTF_KIND_RESTRICT:
+			type_id = t->type;
+			break;
+		case BTF_KIND_ARRAY:
+			array = (const struct btf_array *)(t + 1);
+			if (nelems && array->nelems > UINT32_MAX / nelems)
+				return -E2BIG;
+			nelems *= array->nelems;
+			type_id = array->type;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		t = btf_type_by_id(btf, type_id);
+	}
+
+	if (size < 0)
+		return -EINVAL;
+
+	if (nelems && size > UINT32_MAX / nelems)
+		return -E2BIG;
+
+	return nelems * size;
+}
+
+int32_t btf__find_by_name(const struct btf *btf, const char *type_name)
+{
+	uint32_t i;
+
+	if (!strcmp(type_name, "void"))
+		return 0;
+
+	for (i = 1; i <= btf->nr_types; i++) {
+		const struct btf_type *t = btf->types[i];
+		const char *name = btf_name_by_offset(btf, t->name);
+
+		if (name && !strcmp(type_name, name))
+			return i;
+	}
+
+	return -ENOENT;
+}
+
+void btf__free(struct btf *btf)
+{
+	if (!btf)
+		return;
+
+	if (btf->fd != -1)
+		close(btf->fd);
+
+	free(btf->data);
+	free(btf->types);
+	free(btf);
+}
+
+struct btf *btf__new(uint8_t *data, uint32_t size,
+		     btf_print_fn_t err_log)
+{
+	uint32_t log_buf_size = 0;
+	char *log_buf = NULL;
+	struct btf *btf;
+	int err;
+
+	btf = calloc(1, sizeof(struct btf));
+	if (!btf)
+		return ERR_PTR(-ENOMEM);
+
+	btf->fd = -1;
+
+	if (err_log) {
+		log_buf = malloc(BPF_LOG_BUF_SIZE);
+		if (!log_buf) {
+			err = -ENOMEM;
+			goto done;
+		}
+		*log_buf = 0;
+		log_buf_size = BPF_LOG_BUF_SIZE;
+	}
+
+	btf->data = malloc(size);
+	if (!btf->data) {
+		err = -ENOMEM;
+		goto done;
+	}
+
+	memcpy(btf->data, data, size);
+	btf->data_size = size;
+
+	btf->fd = bpf_load_btf(btf->data, btf->data_size,
+			       log_buf, log_buf_size, false);
+
+	if (btf->fd == -1) {
+		err = -errno;
+		elog("Error loading BTF: %s(%d)\n", strerror(errno), errno);
+		if (log_buf && *log_buf)
+			elog("%s\n", log_buf);
+		goto done;
+	}
+
+	err = btf_parse_hdr(btf, err_log);
+	if (err)
+		goto done;
+
+	err = btf_parse_str_sec(btf, err_log);
+	if (err)
+		goto done;
+
+	err = btf_parse_type_sec(btf, err_log);
+
+done:
+	free(log_buf);
+
+	if (err) {
+		btf__free(btf);
+		return ERR_PTR(err);
+	}
+
+	return btf;
+}
+
+int btf__fd(const struct btf *btf)
+{
+	return btf->fd;
+}

tools/lib/bpf/btf.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2018 Facebook */
+
+#ifndef __BPF_BTF_H
+#define __BPF_BTF_H
+
+#include <stdint.h>
+
+#define BTF_ELF_SEC ".BTF"
+
+struct btf;
+
+typedef int (*btf_print_fn_t)(const char *, ...)
+	__attribute__((format(printf, 1, 2)));
+
+void btf__free(struct btf *btf);
+struct btf *btf__new(uint8_t *data, uint32_t size, btf_print_fn_t err_log);
+int32_t btf__find_by_name(const struct btf *btf, const char *type_name);
+int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id);
+int btf__fd(const struct btf *btf);
+
+#endif

tools/lib/bpf/libbpf.c

@@ -45,6 +45,7 @@
 
 #include "libbpf.h"
 #include "bpf.h"
+#include "btf.h"
 
 #ifndef EM_BPF
 #define EM_BPF 247
@@ -212,6 +213,8 @@ struct bpf_map {
 	char *name;
 	size_t offset;
 	struct bpf_map_def def;
+	uint32_t btf_key_id;
+	uint32_t btf_value_id;
 	void *priv;
 	bpf_map_clear_priv_t clear_priv;
 };
@@ -256,6 +259,8 @@ struct bpf_object {
 	 */
 	struct list_head list;
 
+	struct btf *btf;
+
 	void *priv;
 	bpf_object_clear_priv_t clear_priv;
 
@@ -819,7 +824,15 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
 							data->d_size);
 		else if (strcmp(name, "maps") == 0)
 			obj->efile.maps_shndx = idx;
-		else if (sh.sh_type == SHT_SYMTAB) {
+		else if (strcmp(name, BTF_ELF_SEC) == 0) {
+			obj->btf = btf__new(data->d_buf, data->d_size,
+					    __pr_debug);
+			if (IS_ERR(obj->btf)) {
+				pr_warning("Error loading ELF section %s: %ld. Ignored and continue.\n",
+					   BTF_ELF_SEC, PTR_ERR(obj->btf));
+				obj->btf = NULL;
+			}
+		} else if (sh.sh_type == SHT_SYMTAB) {
 			if (obj->efile.symbols) {
 				pr_warning("bpf: multiple SYMTAB in %s\n",
 					   obj->path);
@@ -996,33 +1009,126 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 	return 0;
 }
 
+static int bpf_map_find_btf_info(struct bpf_map *map, const struct btf *btf)
+{
+	struct bpf_map_def *def = &map->def;
+	const size_t max_name = 256;
+	int64_t key_size, value_size;
+	int32_t key_id, value_id;
+	char name[max_name];
+
+	/* Find key type by name from BTF */
+	if (snprintf(name, max_name, "%s_key", map->name) == max_name) {
+		pr_warning("map:%s length of BTF key_type:%s_key is too long\n",
+			   map->name, map->name);
+		return -EINVAL;
+	}
+
+	key_id = btf__find_by_name(btf, name);
+	if (key_id < 0) {
+		pr_debug("map:%s key_type:%s cannot be found in BTF\n",
+			 map->name, name);
+		return key_id;
+	}
+
+	key_size = btf__resolve_size(btf, key_id);
+	if (key_size < 0) {
+		pr_warning("map:%s key_type:%s cannot get the BTF type_size\n",
+			   map->name, name);
+		return key_size;
+	}
+
+	if (def->key_size != key_size) {
+		pr_warning("map:%s key_type:%s has BTF type_size:%ld != key_size:%u\n",
+			   map->name, name, key_size, def->key_size);
+		return -EINVAL;
+	}
+
+	/* Find value type from BTF */
+	if (snprintf(name, max_name, "%s_value", map->name) == max_name) {
+		pr_warning("map:%s length of BTF value_type:%s_value is too long\n",
+			  map->name, map->name);
+		return -EINVAL;
+	}
+
+	value_id = btf__find_by_name(btf, name);
+	if (value_id < 0) {
+		pr_debug("map:%s value_type:%s cannot be found in BTF\n",
+			 map->name, name);
+		return value_id;
+	}
+
+	value_size = btf__resolve_size(btf, value_id);
+	if (value_size < 0) {
+		pr_warning("map:%s value_type:%s cannot get the BTF type_size\n",
+			   map->name, name);
+		return value_size;
+	}
+
+	if (def->value_size != value_size) {
+		pr_warning("map:%s value_type:%s has BTF type_size:%ld != value_size:%u\n",
+			   map->name, name, value_size, def->value_size);
+		return -EINVAL;
+	}
+
+	map->btf_key_id = key_id;
+	map->btf_value_id = value_id;
+
+	return 0;
+}
+
 static int
 bpf_object__create_maps(struct bpf_object *obj)
 {
+	struct bpf_create_map_attr create_attr = {};
 	unsigned int i;
+	int err;
 
 	for (i = 0; i < obj->nr_maps; i++) {
-		struct bpf_map_def *def = &obj->maps[i].def;
-		int *pfd = &obj->maps[i].fd;
-
-		*pfd = bpf_create_map_name(def->type,
-					   obj->maps[i].name,
-					   def->key_size,
-					   def->value_size,
-					   def->max_entries,
-					   def->map_flags);
+		struct bpf_map *map = &obj->maps[i];
+		struct bpf_map_def *def = &map->def;
+		int *pfd = &map->fd;
+
+		create_attr.name = map->name;
+		create_attr.map_type = def->type;
+		create_attr.map_flags = def->map_flags;
+		create_attr.key_size = def->key_size;
+		create_attr.value_size = def->value_size;
+		create_attr.max_entries = def->max_entries;
+		create_attr.btf_fd = 0;
+		create_attr.btf_key_id = 0;
+		create_attr.btf_value_id = 0;
+
+		if (obj->btf && !bpf_map_find_btf_info(map, obj->btf)) {
+			create_attr.btf_fd = btf__fd(obj->btf);
+			create_attr.btf_key_id = map->btf_key_id;
+			create_attr.btf_value_id = map->btf_value_id;
+		}
+
+		*pfd = bpf_create_map_xattr(&create_attr);
+		if (*pfd < 0 && create_attr.btf_key_id) {
+			pr_warning("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
+				   map->name, strerror(errno), errno);
+			create_attr.btf_fd = 0;
+			create_attr.btf_key_id = 0;
+			create_attr.btf_value_id = 0;
+			map->btf_key_id = 0;
+			map->btf_value_id = 0;
+			*pfd = bpf_create_map_xattr(&create_attr);
+		}
+
 		if (*pfd < 0) {
 			size_t j;
-			int err = *pfd;
 
+			err = *pfd;
 			pr_warning("failed to create map (name: '%s'): %s\n",
-				   obj->maps[i].name,
+				   map->name,
 				   strerror(errno));
 			for (j = 0; j < i; j++)
 				zclose(obj->maps[j].fd);
 			return err;
 		}
-		pr_debug("create map %s: fd=%d\n", obj->maps[i].name, *pfd);
+		pr_debug("create map %s: fd=%d\n", map->name, *pfd);
 	}
 
 	return 0;
@@ -1641,6 +1747,7 @@ void bpf_object__close(struct bpf_object *obj)
 
 	bpf_object__elf_finish(obj);
 	bpf_object__unload(obj);
+	btf__free(obj->btf);
 
 	for (i = 0; i < obj->nr_maps; i++) {
 		zfree(&obj->maps[i].name);
@@ -1692,6 +1799,11 @@ unsigned int bpf_object__kversion(struct bpf_object *obj)
 	return obj ? obj->kern_version : 0;
 }
 
+int bpf_object__btf_fd(const struct bpf_object *obj)
+{
+	return obj->btf ? btf__fd(obj->btf) : -1;
+}
+
 int bpf_object__set_priv(struct bpf_object *obj, void *priv,
 			 bpf_object_clear_priv_t clear_priv)
 {
@@ -1937,6 +2049,16 @@ const char *bpf_map__name(struct bpf_map *map)
 	return map ? map->name : NULL;
 }
 
+uint32_t bpf_map__btf_key_id(const struct bpf_map *map)
+{
+	return map ? map->btf_key_id : 0;
+}
+
+uint32_t bpf_map__btf_value_id(const struct bpf_map *map)
+{
+	return map ? map->btf_value_id : 0;
+}
+
 int bpf_map__set_priv(struct bpf_map *map, void *priv,
 		     bpf_map_clear_priv_t clear_priv)
 {

tools/lib/bpf/libbpf.h

@@ -78,6 +78,7 @@ int bpf_object__load(struct bpf_object *obj);
 int bpf_object__unload(struct bpf_object *obj);
 const char *bpf_object__name(struct bpf_object *obj);
 unsigned int bpf_object__kversion(struct bpf_object *obj);
+int bpf_object__btf_fd(const struct bpf_object *obj);
 
 struct bpf_object *bpf_object__next(struct bpf_object *prev);
 #define bpf_object__for_each_safe(pos, tmp)			\
@@ -241,6 +242,8 @@ bpf_map__next(struct bpf_map *map, struct bpf_object *obj);
 int bpf_map__fd(struct bpf_map *map);
 const struct bpf_map_def *bpf_map__def(struct bpf_map *map);
 const char *bpf_map__name(struct bpf_map *map);
+uint32_t bpf_map__btf_key_id(const struct bpf_map *map);
+uint32_t bpf_map__btf_value_id(const struct bpf_map *map);
 
 typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *);
 int bpf_map__set_priv(struct bpf_map *map, void *priv,

tools/testing/selftests/bpf/Makefile

@@ -24,14 +24,15 @@ urandom_read: urandom_read.c
 # Order correspond to 'make run_tests' order
 TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \
 	test_align test_verifier_log test_dev_cgroup test_tcpbpf_user \
-	test_sock test_sock_addr
+	test_sock test_sock_addr test_btf
 
 TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test_obj_id.o \
 	test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o     \
 	sockmap_verdict_prog.o dev_cgroup.o sample_ret0.o test_tracepoint.o \
 	test_l4lb_noinline.o test_xdp_noinline.o test_stacktrace_map.o \
 	sample_map_ret0.o test_tcpbpf_kern.o test_stacktrace_build_id.o \
-	sockmap_tcp_msg_prog.o connect4_prog.o connect6_prog.o test_adjust_tail.o
+	sockmap_tcp_msg_prog.o connect4_prog.o connect6_prog.o test_adjust_tail.o \
+	test_btf_haskv.o test_btf_nokv.o
 
 # Order correspond to 'make run_tests' order
 TEST_PROGS := test_kmod.sh \
@@ -66,6 +67,8 @@ $(BPFOBJ): force
 
 CLANG ?= clang
 LLC   ?= llc
+LLVM_OBJCOPY ?= llvm-objcopy
+BTF_PAHOLE ?= pahole
 
 PROBE := $(shell $(LLC) -march=bpf -mcpu=probe -filetype=null /dev/null 2>&1)
 
@@ -83,9 +86,26 @@ CLANG_FLAGS = -I. -I./include/uapi -I../../../include/uapi \
 $(OUTPUT)/test_l4lb_noinline.o: CLANG_FLAGS += -fno-inline
 $(OUTPUT)/test_xdp_noinline.o: CLANG_FLAGS += -fno-inline
 
+BTF_LLC_PROBE := $(shell $(LLC) -march=bpf -mattr=help |& grep dwarfris)
+BTF_PAHOLE_PROBE := $(shell $(BTF_PAHOLE) --help |& grep BTF)
+BTF_OBJCOPY_PROBE := $(shell $(LLVM_OBJCOPY) --version |& grep LLVM)
+
+ifneq ($(BTF_LLC_PROBE),)
+ifneq ($(BTF_PAHOLE_PROBE),)
+ifneq ($(BTF_OBJCOPY_PROBE),)
+	CLANG_FLAGS += -g
+	LLC_FLAGS += -mattr=dwarfris
+	DWARF2BTF = y
+endif
+endif
+endif
+
 $(OUTPUT)/%.o: %.c
 	$(CLANG) $(CLANG_FLAGS) \
 		 -O2 -target bpf -emit-llvm -c $< -o - |      \
-	$(LLC) -march=bpf -mcpu=$(CPU) -filetype=obj -o $@
+	$(LLC) -march=bpf -mcpu=$(CPU) $(LLC_FLAGS) -filetype=obj -o $@
+ifeq ($(DWARF2BTF),y)
+	$(BTF_PAHOLE) -J $@
+endif
 
 EXTRA_CLEAN := $(TEST_CUSTOM_PROGS)

tools/testing/selftests/bpf/test_btf.c

+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2018 Facebook */
+
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/err.h>
+#include <bpf/bpf.h>
+#include <sys/resource.h>
+#include <libelf.h>
+#include <gelf.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <bpf/libbpf.h>
+#include <bpf/btf.h>
+
+#include "bpf_rlimit.h"
+
+#define min(a, b) ((a) < (b) ? (a) : (b))
+#define __printf(a, b)	__attribute__((format(printf, a, b)))
+
+__printf(1, 2)
+static int __base_pr(const char *format, ...)
+{
+	va_list args;
+	int err;
+
+	va_start(args, format);
+	err = vfprintf(stderr, format, args);
+	va_end(args);
+	return err;
+}
+
+#define BTF_INFO_ENC(kind, root, vlen)			\
+	((!!(root) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
+
+#define BTF_TYPE_ENC(name, info, size_or_type)	\
+	(name), (info), (size_or_type)
+
+#define BTF_INT_ENC(encoding, bits_offset, nr_bits)	\
+	((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
+#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz)	\
+	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz),	\
+	BTF_INT_ENC(encoding, bits_offset, bits)
+
+#define BTF_ARRAY_ENC(type, index_type, nr_elems)	\
+	(type), (index_type), (nr_elems)
+#define BTF_TYPE_ARRAY_ENC(type, index_type, nr_elems) \
+	BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_ARRAY, 0, 0), 0), \
+	BTF_ARRAY_ENC(type, index_type, nr_elems)
+
+#define BTF_MEMBER_ENC(name, type, bits_offset)	\
+	(name), (type), (bits_offset)
+#define BTF_ENUM_ENC(name, val) (name), (val)
+
+#define BTF_TYPEDEF_ENC(name, type) \
+	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0), type)
+
+#define BTF_PTR_ENC(name, type) \
+	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), type)
+
+#define BTF_END_RAW 0xdeadbeef
+#define NAME_TBD 0xdeadb33f
+
+#define MAX_NR_RAW_TYPES 1024
+#define BTF_LOG_BUF_SIZE 65535
+
+#ifndef ARRAY_SIZE
+# define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+#endif
+
+static struct args {
+	unsigned int raw_test_num;
+	unsigned int file_test_num;
+	unsigned int get_info_test_num;
+	bool raw_test;
+	bool file_test;
+	bool get_info_test;
+	bool pprint_test;
+	bool always_log;
+} args;
+
+static char btf_log_buf[BTF_LOG_BUF_SIZE];
+
+static struct btf_header hdr_tmpl = {
+	.magic = BTF_MAGIC,
+	.version = BTF_VERSION,
+};
+
+struct btf_raw_test {
+	const char *descr;
+	const char *str_sec;
+	const char *map_name;
+	__u32 raw_types[MAX_NR_RAW_TYPES];
+	__u32 str_sec_size;
+	enum bpf_map_type map_type;
+	__u32 key_size;
+	__u32 value_size;
+	__u32 key_id;
+	__u32 value_id;
+	__u32 max_entries;
+	bool btf_load_err;
+	bool map_create_err;
+	int type_off_delta;
+	int str_off_delta;
+	int str_len_delta;
+};
+
+static struct btf_raw_test raw_tests[] = {
+/* enum E {
+ *     E0,
+ *     E1,
+ * };
+ *
+ * struct A {
+ *	int m;
+ *	unsigned long long n;
+ *	char o;
+ *	[3 bytes hole]
+ *	int p[8];
+ *	int q[4][8];
+ *	enum E r;
+ * };
+ */
+{
+	.descr = "struct test #1",
+	.raw_types = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),	/* [1] */
+		/* unsigned long long */
+		BTF_TYPE_INT_ENC(0, 0, 0, 64, 8),		/* [2] */
+		/* char */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 8, 1),	/* [3] */
+		/* int[8] */
+		BTF_TYPE_ARRAY_ENC(1, 1, 8),			/* [4] */
+		/* struct A { */				/* [5] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 6), 180),
+		BTF_MEMBER_ENC(NAME_TBD, 1, 0),	/* int m;		*/
+		BTF_MEMBER_ENC(NAME_TBD, 2, 32),/* unsigned long long n;*/
+		BTF_MEMBER_ENC(NAME_TBD, 3, 96),/* char o;		*/
+		BTF_MEMBER_ENC(NAME_TBD, 4, 128),/* int p[8]		*/
+		BTF_MEMBER_ENC(NAME_TBD, 6, 384),/* int q[4][8]		*/
+		BTF_MEMBER_ENC(NAME_TBD, 7, 1408), /* enum E r		*/
+		/* } */
+		/* int[4][8] */
+		BTF_TYPE_ARRAY_ENC(4, 1, 4),			/* [6] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_ENUM, 0, 2), sizeof(int)),
+		BTF_ENUM_ENC(NAME_TBD, 0),
+		BTF_ENUM_ENC(NAME_TBD, 1),
+		BTF_END_RAW,
+	},
+	.str_sec = "\0A\0m\0n\0o\0p\0q\0r\0E\0E0\0E1",
+	.str_sec_size = sizeof("\0A\0m\0n\0o\0p\0q\0r\0E\0E0\0E1"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "struct_test1_map",
+	.key_size = sizeof(int),
+	.value_size = 180,
+	.key_id = 1,
+	.value_id = 5,
+	.max_entries = 4,
+},
+
+/* typedef struct b Struct_B;
+ *
+ * struct A {
+ *     int m;
+ *     struct b n[4];
+ *     const Struct_B o[4];
+ * };
+ *
+ * struct B {
+ *     int m;
+ *     int n;
+ * };
+ */
+{
+	.descr = "struct test #2",
+	.raw_types = {
+		/* int */					/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		/* struct b [4] */				/* [2] */
+		BTF_TYPE_ARRAY_ENC(4, 1, 4),
+
+		/* struct A { */				/* [3] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 3), 68),
+		BTF_MEMBER_ENC(NAME_TBD, 1, 0),	/* int m;		*/
+		BTF_MEMBER_ENC(NAME_TBD, 2, 32),/* struct B n[4]	*/
+		BTF_MEMBER_ENC(NAME_TBD, 8, 288),/* const Struct_B o[4];*/
+		/* } */
+
+		/* struct B { */				/* [4] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
+		BTF_MEMBER_ENC(NAME_TBD, 1, 0),	/* int m; */
+		BTF_MEMBER_ENC(NAME_TBD, 1, 32),/* int n; */
+		/* } */
+
+		/* const int */					/* [5] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_CONST, 0, 0), 1),
+		/* typedef struct b Struct_B */	/* [6] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0), 4),
+		/* const Struct_B */				/* [7] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_CONST, 0, 0), 6),
+		/* const Struct_B [4] */			/* [8] */
+		BTF_TYPE_ARRAY_ENC(7, 1, 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "\0A\0m\0n\0o\0B\0m\0n\0Struct_B",
+	.str_sec_size = sizeof("\0A\0m\0n\0o\0B\0m\0n\0Struct_B"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "struct_test2_map",
+	.key_size = sizeof(int),
+	.value_size = 68,
+	.key_id = 1,
+	.value_id = 3,
+	.max_entries = 4,
+},
+
+/* Test member exceeds the size of struct.
+ *
+ * struct A {
+ *     int m;
+ *     int n;
+ * };
+ */
+{
+	.descr = "size check test #1",
+	.raw_types = {
+		/* int */					/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		/* struct A { */				/* [2] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), sizeof(int) * 2 -  1),
+		BTF_MEMBER_ENC(NAME_TBD, 1, 0),	/* int m; */
+		BTF_MEMBER_ENC(NAME_TBD, 2, 32),/* int n; */
+		/* } */
+		BTF_END_RAW,
+	},
+	.str_sec = "\0A\0m\0n",
+	.str_sec_size = sizeof("\0A\0m\0n"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "size_check1_map",
+	.key_size = sizeof(int),
+	.value_size = 1,
+	.key_id = 1,
+	.value_id = 2,
+	.max_entries = 4,
+	.btf_load_err = true,
+},
+
+/* Test member exeeds the size of struct
+ *
+ * struct A {
+ *     int m;
+ *     int n[2];
+ * };
+ */
+{
+	.descr = "size check test #2",
+	.raw_types = {
+		/* int */					/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, sizeof(int)),
+		/* int[2] */					/* [2] */
+		BTF_TYPE_ARRAY_ENC(1, 1, 2),
+		/* struct A { */				/* [3] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), sizeof(int) * 3 - 1),
+		BTF_MEMBER_ENC(NAME_TBD, 1, 0),	/* int m; */
+		BTF_MEMBER_ENC(NAME_TBD, 2, 32),/* int n[2]; */
+		/* } */
+		BTF_END_RAW,
+	},
+	.str_sec = "\0A\0m\0n",
+	.str_sec_size = sizeof("\0A\0m\0n"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "size_check2_map",
+	.key_size = sizeof(int),
+	.value_size = 1,
+	.key_id = 1,
+	.value_id = 3,
+	.max_entries = 4,
+	.btf_load_err = true,
+
+},
+
+/* Test member exeeds the size of struct
+ *
+ * struct A {
+ *     int m;
+ *     void *n;
+ * };
+ */
+{
+	.descr = "size check test #3",
+	.raw_types = {
+		/* int */					/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, sizeof(int)),
+		/* void* */					/* [2] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 0),
+		/* struct A { */				/* [3] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), sizeof(int) + sizeof(void *) - 1),
+		BTF_MEMBER_ENC(NAME_TBD, 1, 0),	/* int m; */
+		BTF_MEMBER_ENC(NAME_TBD, 2, 32),/* void *n; */
+		/* } */
+		BTF_END_RAW,
+	},
+	.str_sec = "\0A\0m\0n",
+	.str_sec_size = sizeof("\0A\0m\0n"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "size_check3_map",
+	.key_size = sizeof(int),
+	.value_size = 1,
+	.key_id = 1,
+	.value_id = 3,
+	.max_entries = 4,
+	.btf_load_err = true,
+},
+
+/* Test member exceeds the size of struct
+ *
+ * enum E {
+ *     E0,
+ *     E1,
+ * };
+ *
+ * struct A {
+ *     int m;
+ *     enum E n;
+ * };
+ */
+{
+	.descr = "size check test #4",
+	.raw_types = {
+		/* int */			/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, sizeof(int)),
+		/* enum E { */			/* [2] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_ENUM, 0, 2), sizeof(int)),
+		BTF_ENUM_ENC(NAME_TBD, 0),
+		BTF_ENUM_ENC(NAME_TBD, 1),
+		/* } */
+		/* struct A { */		/* [3] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), sizeof(int) * 2 - 1),
+		BTF_MEMBER_ENC(NAME_TBD, 1, 0),	/* int m; */
+		BTF_MEMBER_ENC(NAME_TBD, 2, 32),/* enum E n; */
+		/* } */
+		BTF_END_RAW,
+	},
+	.str_sec = "\0E\0E0\0E1\0A\0m\0n",
+	.str_sec_size = sizeof("\0E\0E0\0E1\0A\0m\0n"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "size_check4_map",
+	.key_size = sizeof(int),
+	.value_size = 1,
+	.key_id = 1,
+	.value_id = 3,
+	.max_entries = 4,
+	.btf_load_err = true,
+},
+
+/* typedef const void * const_void_ptr;
+ * struct A {
+ *	const_void_ptr m;
+ * };
+ */
+{
+	.descr = "void test #1",
+	.raw_types = {
+		/* int */		/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		/* const void */	/* [2] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_CONST, 0, 0), 0),
+		/* const void* */	/* [3] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 2),
+		/* typedef const void * const_void_ptr */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 3),
+		/* struct A { */	/* [4] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), sizeof(void *)),
+		/* const_void_ptr m; */
+		BTF_MEMBER_ENC(NAME_TBD, 3, 0),
+		/* } */
+		BTF_END_RAW,
+	},
+	.str_sec = "\0const_void_ptr\0A\0m",
+	.str_sec_size = sizeof("\0const_void_ptr\0A\0m"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "void_test1_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(void *),
+	.key_id = 1,
+	.value_id = 4,
+	.max_entries = 4,
+},
+
+/* struct A {
+ *     const void m;
+ * };
+ */
+{
+	.descr = "void test #2",
+	.raw_types = {
+		/* int */		/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		/* const void */	/* [2] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_CONST, 0, 0), 0),
+		/* struct A { */	/* [3] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 8),
+		/* const void m; */
+		BTF_MEMBER_ENC(NAME_TBD, 2, 0),
+		/* } */
+		BTF_END_RAW,
+	},
+	.str_sec = "\0A\0m",
+	.str_sec_size = sizeof("\0A\0m"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "void_test2_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(void *),
+	.key_id = 1,
+	.value_id = 3,
+	.max_entries = 4,
+	.btf_load_err = true,
+},
+
+/* typedef const void * const_void_ptr;
+ * const_void_ptr[4]
+ */
+{
+	.descr = "void test #3",
+	.raw_types = {
+		/* int */		/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		/* const void */	/* [2] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_CONST, 0, 0), 0),
+		/* const void* */	/* [3] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 2),
+		/* typedef const void * const_void_ptr */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 3),
+		/* const_void_ptr[4] */	/* [4] */
+		BTF_TYPE_ARRAY_ENC(3, 1, 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "\0const_void_ptr",
+	.str_sec_size = sizeof("\0const_void_ptr"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "void_test3_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(void *) * 4,
+	.key_id = 1,
+	.value_id = 4,
+	.max_entries = 4,
+},
+
+/* const void[4]  */
+{
+	.descr = "void test #4",
+	.raw_types = {
+		/* int */		/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		/* const void */	/* [2] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_CONST, 0, 0), 0),
+		/* const void[4] */	/* [3] */
+		BTF_TYPE_ARRAY_ENC(2, 1, 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "\0A\0m",
+	.str_sec_size = sizeof("\0A\0m"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "void_test4_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(void *) * 4,
+	.key_id = 1,
+	.value_id = 3,
+	.max_entries = 4,
+	.btf_load_err = true,
+},
+
+/* Array_A  <------------------+
+ *     elem_type == Array_B    |
+ *                    |        |
+ *                    |        |
+ * Array_B  <-------- +        |
+ *      elem_type == Array A --+
+ */
+{
+	.descr = "loop test #1",
+	.raw_types = {
+		/* int */			/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		/* Array_A */			/* [2] */
+		BTF_TYPE_ARRAY_ENC(3, 1, 8),
+		/* Array_B */			/* [3] */
+		BTF_TYPE_ARRAY_ENC(2, 1, 8),
+		BTF_END_RAW,
+	},
+	.str_sec = "",
+	.str_sec_size = sizeof(""),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "loop_test1_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(sizeof(int) * 8),
+	.key_id = 1,
+	.value_id = 2,
+	.max_entries = 4,
+	.btf_load_err = true,
+},
+
+/* typedef is _before_ the BTF type of Array_A and Array_B
+ *
+ * typedef Array_B int_array;
+ *
+ * Array_A  <------------------+
+ *     elem_type == int_array  |
+ *                    |        |
+ *                    |        |
+ * Array_B  <-------- +        |
+ *      elem_type == Array_A --+
+ */
+{
+	.descr = "loop test #2",
+	.raw_types = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),	/* [1] */
+		/* typedef Array_B int_array */
+		BTF_TYPEDEF_ENC(1, 4),				/* [2] */
+		/* Array_A */
+		BTF_TYPE_ARRAY_ENC(2, 1, 8),			/* [3] */
+		/* Array_B */
+		BTF_TYPE_ARRAY_ENC(3, 1, 8),			/* [4] */
+
+		BTF_END_RAW,
+	},
+	.str_sec = "\0int_array\0",
+	.str_sec_size = sizeof("\0int_array"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "loop_test2_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(sizeof(int) * 8),
+	.key_id = 1,
+	.value_id = 2,
+	.max_entries = 4,
+	.btf_load_err = true,
+},
+
+/* Array_A  <------------------+
+ *     elem_type == Array_B    |
+ *                    |        |
+ *                    |        |
+ * Array_B  <-------- +        |
+ *      elem_type == Array_A --+
+ */
+{
+	.descr = "loop test #3",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		/* Array_A */				/* [2] */
+		BTF_TYPE_ARRAY_ENC(3, 1, 8),
+		/* Array_B */				/* [3] */
+		BTF_TYPE_ARRAY_ENC(2, 1, 8),
+
+		BTF_END_RAW,
+	},
+	.str_sec = "",
+	.str_sec_size = sizeof(""),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "loop_test3_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(sizeof(int) * 8),
+	.key_id = 1,
+	.value_id = 2,
+	.max_entries = 4,
+	.btf_load_err = true,
+},
+
+/* typedef is _between_ the BTF type of Array_A and Array_B
+ *
+ * typedef Array_B int_array;
+ *
+ * Array_A  <------------------+
+ *     elem_type == int_array  |
+ *                    |        |
+ *                    |        |
+ * Array_B  <-------- +        |
+ *      elem_type == Array_A --+
+ */
+{
+	.descr = "loop test #4",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		/* Array_A */				/* [2] */
+		BTF_TYPE_ARRAY_ENC(3, 1, 8),
+		/* typedef Array_B int_array */		/* [3] */
+		BTF_TYPEDEF_ENC(NAME_TBD, 4),
+		/* Array_B */				/* [4] */
+		BTF_TYPE_ARRAY_ENC(2, 1, 8),
+		BTF_END_RAW,
+	},
+	.str_sec = "\0int_array\0",
+	.str_sec_size = sizeof("\0int_array"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "loop_test4_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(sizeof(int) * 8),
+	.key_id = 1,
+	.value_id = 2,
+	.max_entries = 4,
+	.btf_load_err = true,
+},
+
+/* typedef struct B Struct_B
+ *
+ * struct A {
+ *     int x;
+ *     Struct_B y;
+ * };
+ *
+ * struct B {
+ *     int x;
+ *     struct A y;
+ * };
+ */
+{
+	.descr = "loop test #5",
+	.raw_types = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),	/* [1] */
+		/* struct A */					/* [2] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
+		BTF_MEMBER_ENC(NAME_TBD, 1, 0),	/* int x;	*/
+		BTF_MEMBER_ENC(NAME_TBD, 3, 32),/* Struct_B y;	*/
+		/* typedef struct B Struct_B */
+		BTF_TYPEDEF_ENC(NAME_TBD, 4),			/* [3] */
+		/* struct B */					/* [4] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
+		BTF_MEMBER_ENC(NAME_TBD, 1, 0),	/* int x;	*/
+		BTF_MEMBER_ENC(NAME_TBD, 2, 32),/* struct A y;	*/
+		BTF_END_RAW,
+	},
+	.str_sec = "\0A\0x\0y\0Struct_B\0B\0x\0y",
+	.str_sec_size = sizeof("\0A\0x\0y\0Struct_B\0B\0x\0y"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "loop_test5_map",
+	.key_size = sizeof(int),
+	.value_size = 8,
+	.key_id = 1,
+	.value_id = 2,
+	.max_entries = 4,
+	.btf_load_err = true,
+},
+
+/* struct A {
+ *     int x;
+ *     struct A array_a[4];
+ * };
+ */
+{
+	.descr = "loop test #6",
+	.raw_types = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),	/* [1] */
+		BTF_TYPE_ARRAY_ENC(3, 1, 4),			/* [2] */
+		/* struct A */					/* [3] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
+		BTF_MEMBER_ENC(NAME_TBD, 1, 0),	/* int x;		*/
+		BTF_MEMBER_ENC(NAME_TBD, 2, 32),/* struct A array_a[4];	*/
+		BTF_END_RAW,
+	},
+	.str_sec = "\0A\0x\0y",
+	.str_sec_size = sizeof("\0A\0x\0y"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "loop_test6_map",
+	.key_size = sizeof(int),
+	.value_size = 8,
+	.key_id = 1,
+	.value_id = 2,
+	.max_entries = 4,
+	.btf_load_err = true,
+},
+
+{
+	.descr = "loop test #7",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		/* struct A { */			/* [2] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), sizeof(void *)),
+		/*     const void *m;	*/
+		BTF_MEMBER_ENC(NAME_TBD, 3, 0),
+		/* CONST type_id=3	*/		/* [3] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_CONST, 0, 0), 4),
+		/* PTR type_id=2	*/		/* [4] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 3),
+		BTF_END_RAW,
+	},
+	.str_sec = "\0A\0m",
+	.str_sec_size = sizeof("\0A\0m"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "loop_test7_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(void *),
+	.key_id = 1,
+	.value_id = 2,
+	.max_entries = 4,
+	.btf_load_err = true,
+},
+
+{
+	.descr = "loop test #8",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		/* struct A { */			/* [2] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), sizeof(void *)),
+		/*     const void *m;	*/
+		BTF_MEMBER_ENC(NAME_TBD, 4, 0),
+		/* struct B { */			/* [3] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), sizeof(void *)),
+		/*     const void *n;	*/
+		BTF_MEMBER_ENC(NAME_TBD, 6, 0),
+		/* CONST type_id=5	*/		/* [4] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_CONST, 0, 0), 5),
+		/* PTR type_id=6	*/		/* [5] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 6),
+		/* CONST type_id=7	*/		/* [6] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_CONST, 0, 0), 7),
+		/* PTR type_id=4	*/		/* [7] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "\0A\0m\0B\0n",
+	.str_sec_size = sizeof("\0A\0m\0B\0n"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "loop_test8_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(void *),
+	.key_id = 1,
+	.value_id = 2,
+	.max_entries = 4,
+	.btf_load_err = true,
+},
+
+{
+	.descr = "type_off == str_off",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "\0int",
+	.str_sec_size = sizeof("\0int"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "hdr_test_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(int),
+	.key_id = 1,
+	.value_id = 1,
+	.max_entries = 4,
+	.btf_load_err = true,
+	.type_off_delta = sizeof(struct btf_type) + sizeof(int) + sizeof("\0int"),
+},
+
+{
+	.descr = "Unaligned type_off",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "\0int",
+	.str_sec_size = sizeof("\0int"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "hdr_test_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(int),
+	.key_id = 1,
+	.value_id = 1,
+	.max_entries = 4,
+	.btf_load_err = true,
+	.type_off_delta = 1,
+},
+
+{
+	.descr = "str_off beyonds btf size",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "\0int",
+	.str_sec_size = sizeof("\0int"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "hdr_test_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(int),
+	.key_id = 1,
+	.value_id = 1,
+	.max_entries = 4,
+	.btf_load_err = true,
+	.str_off_delta = sizeof("\0int") + 1,
+},
+
+{
+	.descr = "str_len beyonds btf size",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "\0int",
+	.str_sec_size = sizeof("\0int"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "hdr_test_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(int),
+	.key_id = 1,
+	.value_id = 1,
+	.max_entries = 4,
+	.btf_load_err = true,
+	.str_len_delta = 1,
+},
+
+{
+	.descr = "String section does not end with null",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "\0int",
+	.str_sec_size = sizeof("\0int"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "hdr_test_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(int),
+	.key_id = 1,
+	.value_id = 1,
+	.max_entries = 4,
+	.btf_load_err = true,
+	.str_len_delta = -1,
+},
+
+{
+	.descr = "Empty string section",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "\0int",
+	.str_sec_size = sizeof("\0int"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "hdr_test_map",
+	.key_size = sizeof(int),
+	.value_size = sizeof(int),
+	.key_id = 1,
+	.value_id = 1,
+	.max_entries = 4,
+	.btf_load_err = true,
+	.str_len_delta = 0 - (int)sizeof("\0int"),
+},
+
+}; /* struct btf_raw_test raw_tests[] */
+
+static const char *get_next_str(const char *start, const char *end)
+{
+	return start < end - 1 ? start + 1 : NULL;
+}
+
+static int get_type_sec_size(const __u32 *raw_types)
+{
+	int i;
+
+	for (i = MAX_NR_RAW_TYPES - 1;
+	     i >= 0 && raw_types[i] != BTF_END_RAW;
+	     i--)
+		;
+
+	return i < 0 ? i : i * sizeof(raw_types[0]);
+}
+
+static void *btf_raw_create(const struct btf_header *hdr,
+			    const __u32 *raw_types,
+			    const char *str,
+			    unsigned int str_sec_size,
+			    unsigned int *btf_size)
+{
+	const char *next_str = str, *end_str = str + str_sec_size;
+	unsigned int size_needed, offset;
+	struct btf_header *ret_hdr;
+	int i, type_sec_size;
+	uint32_t *ret_types;
+	void *raw_btf;
+
+	type_sec_size = get_type_sec_size(raw_types);
+	if (type_sec_size < 0) {
+		fprintf(stderr, "Cannot get nr_raw_types\n");
+		return NULL;
+	}
+
+	size_needed = sizeof(*hdr) + type_sec_size + str_sec_size;
+	raw_btf = malloc(size_needed);
+	if (!raw_btf) {
+		fprintf(stderr, "Cannot allocate memory for raw_btf\n");
+		return NULL;
+	}
+
+	/* Copy header */
+	memcpy(raw_btf, hdr, sizeof(*hdr));
+	offset = sizeof(*hdr);
+
+	/* Copy type section */
+	ret_types = raw_btf + offset;
+	for (i = 0; i < type_sec_size / sizeof(raw_types[0]); i++) {
+		if (raw_types[i] == NAME_TBD) {
+			next_str = get_next_str(next_str, end_str);
+			if (!next_str) {
+				fprintf(stderr, "Error in getting next_str\n");
+				free(raw_btf);
+				return NULL;
+			}
+			ret_types[i] = next_str - str;
+			next_str += strlen(next_str);
+		} else {
+			ret_types[i] = raw_types[i];
+		}
+	}
+	offset += type_sec_size;
+
+	/* Copy string section */
+	memcpy(raw_btf + offset, str, str_sec_size);
+
+	ret_hdr = (struct btf_header *)raw_btf;
+	ret_hdr->str_off = type_sec_size;
+	ret_hdr->str_len = str_sec_size;
+
+	*btf_size = size_needed;
+
+	return raw_btf;
+}
+
+static int do_test_raw(unsigned int test_num)
+{
+	struct btf_raw_test *test = &raw_tests[test_num - 1];
+	struct bpf_create_map_attr create_attr = {};
+	int map_fd = -1, btf_fd = -1;
+	unsigned int raw_btf_size;
+	struct btf_header *hdr;
+	void *raw_btf;
+	int err;
+
+	fprintf(stderr, "BTF raw test[%u] (%s): ", test_num, test->descr);
+	raw_btf = btf_raw_create(&hdr_tmpl,
+				 test->raw_types,
+				 test->str_sec,
+				 test->str_sec_size,
+				 &raw_btf_size);
+
+	if (!raw_btf)
+		return -1;
+
+	hdr = raw_btf;
+
+	hdr->type_off = (int)hdr->type_off + test->type_off_delta;
+	hdr->str_off = (int)hdr->str_off + test->str_off_delta;
+	hdr->str_len = (int)hdr->str_len + test->str_len_delta;
+
+	*btf_log_buf = '\0';
+	btf_fd = bpf_load_btf(raw_btf, raw_btf_size,
+			      btf_log_buf, BTF_LOG_BUF_SIZE,
+			      args.always_log);
+	free(raw_btf);
+
+	err = ((btf_fd == -1) != test->btf_load_err);
+	if (err)
+		fprintf(stderr, "btf_load_err:%d btf_fd:%d\n",
+			test->btf_load_err, btf_fd);
+
+	if (err || btf_fd == -1)
+		goto done;
+
+	create_attr.name = test->map_name;
+	create_attr.map_type = test->map_type;
+	create_attr.key_size = test->key_size;
+	create_attr.value_size = test->value_size;
+	create_attr.max_entries = test->max_entries;
+	create_attr.btf_fd = btf_fd;
+	create_attr.btf_key_id = test->key_id;
+	create_attr.btf_value_id = test->value_id;
+
+	map_fd = bpf_create_map_xattr(&create_attr);
+
+	err = ((map_fd == -1) != test->map_create_err);
+	if (err)
+		fprintf(stderr, "map_create_err:%d map_fd:%d\n",
+			test->map_create_err, map_fd);
+
+done:
+	if (!err)
+		fprintf(stderr, "OK\n");
+
+	if (*btf_log_buf && (err || args.always_log))
+		fprintf(stderr, "%s\n", btf_log_buf);
+
+	if (btf_fd != -1)
+		close(btf_fd);
+	if (map_fd != -1)
+		close(map_fd);
+
+	return err;
+}
+
+static int test_raw(void)
+{
+	unsigned int i;
+	int err = 0;
+
+	if (args.raw_test_num)
+		return do_test_raw(args.raw_test_num);
+
+	for (i = 1; i <= ARRAY_SIZE(raw_tests); i++)
+		err |= do_test_raw(i);
+
+	return err;
+}
+
+struct btf_get_info_test {
+	const char *descr;
+	const char *str_sec;
+	__u32 raw_types[MAX_NR_RAW_TYPES];
+	__u32 str_sec_size;
+	int info_size_delta;
+};
+
+const struct btf_get_info_test get_info_tests[] = {
+{
+	.descr = "== raw_btf_size+1",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "",
+	.str_sec_size = sizeof(""),
+	.info_size_delta = 1,
+},
+{
+	.descr = "== raw_btf_size-3",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "",
+	.str_sec_size = sizeof(""),
+	.info_size_delta = -3,
+},
+};
+
+static int do_test_get_info(unsigned int test_num)
+{
+	const struct btf_get_info_test *test = &get_info_tests[test_num - 1];
+	unsigned int raw_btf_size, user_btf_size, expected_nbytes;
+	uint8_t *raw_btf = NULL, *user_btf = NULL;
+	int btf_fd = -1, err;
+
+	fprintf(stderr, "BTF GET_INFO_BY_ID test[%u] (%s): ",
+		test_num, test->descr);
+
+	raw_btf = btf_raw_create(&hdr_tmpl,
+				 test->raw_types,
+				 test->str_sec,
+				 test->str_sec_size,
+				 &raw_btf_size);
+
+	if (!raw_btf)
+		return -1;
+
+	*btf_log_buf = '\0';
+
+	user_btf = malloc(raw_btf_size);
+	if (!user_btf) {
+		fprintf(stderr, "Cannot allocate memory for user_btf\n");
+		err = -1;
+		goto done;
+	}
+
+	btf_fd = bpf_load_btf(raw_btf, raw_btf_size,
+			      btf_log_buf, BTF_LOG_BUF_SIZE,
+			      args.always_log);
+	if (btf_fd == -1) {
+		fprintf(stderr, "bpf_load_btf:%s(%d)\n",
+			strerror(errno), errno);
+		err = -1;
+		goto done;
+	}
+
+	user_btf_size = (int)raw_btf_size + test->info_size_delta;
+	expected_nbytes = min(raw_btf_size, user_btf_size);
+	if (raw_btf_size > expected_nbytes)
+		memset(user_btf + expected_nbytes, 0xff,
+		       raw_btf_size - expected_nbytes);
+
+	err = bpf_obj_get_info_by_fd(btf_fd, user_btf, &user_btf_size);
+	if (err || user_btf_size != raw_btf_size ||
+	    memcmp(raw_btf, user_btf, expected_nbytes)) {
+		fprintf(stderr,
+			"err:%d(errno:%d) raw_btf_size:%u user_btf_size:%u expected_nbytes:%u memcmp:%d\n",
+			err, errno,
+			raw_btf_size, user_btf_size, expected_nbytes,
+			memcmp(raw_btf, user_btf, expected_nbytes));
+		err = -1;
+		goto done;
+	}
+
+	while (expected_nbytes < raw_btf_size) {
+		fprintf(stderr, "%u...", expected_nbytes);
+		if (user_btf[expected_nbytes++] != 0xff) {
+			fprintf(stderr, "!= 0xff\n");
+			err = -1;
+			goto done;
+		}
+	}
+
+	fprintf(stderr, "OK\n");
+
+done:
+	if (*btf_log_buf && (err || args.always_log))
+		fprintf(stderr, "%s\n", btf_log_buf);
+
+	free(raw_btf);
+	free(user_btf);
+
+	if (btf_fd != -1)
+		close(btf_fd);
+
+	return err;
+}
+
+static int test_get_info(void)
+{
+	unsigned int i;
+	int err = 0;
+
+	if (args.get_info_test_num)
+		return do_test_get_info(args.get_info_test_num);
+
+	for (i = 1; i <= ARRAY_SIZE(get_info_tests); i++)
+		err |= do_test_get_info(i);
+
+	return err;
+}
+
+struct btf_file_test {
+	const char *file;
+	bool btf_kv_notfound;
+};
+
+static struct btf_file_test file_tests[] = {
+{
+	.file = "test_btf_haskv.o",
+},
+{
+	.file = "test_btf_nokv.o",
+	.btf_kv_notfound = true,
+},
+};
+
+static int file_has_btf_elf(const char *fn)
+{
+	Elf_Scn *scn = NULL;
+	GElf_Ehdr ehdr;
+	int elf_fd;
+	Elf *elf;
+	int ret;
+
+	if (elf_version(EV_CURRENT) == EV_NONE) {
+		fprintf(stderr, "Failed to init libelf\n");
+		return -1;
+	}
+
+	elf_fd = open(fn, O_RDONLY);
+	if (elf_fd == -1) {
+		fprintf(stderr, "Cannot open file %s: %s(%d)\n",
+			fn, strerror(errno), errno);
+		return -1;
+	}
+
+	elf = elf_begin(elf_fd, ELF_C_READ, NULL);
+	if (!elf) {
+		fprintf(stderr, "Failed to read ELF from %s. %s\n", fn,
+			elf_errmsg(elf_errno()));
+		ret = -1;
+		goto done;
+	}
+
+	if (!gelf_getehdr(elf, &ehdr)) {
+		fprintf(stderr, "Failed to get EHDR from %s\n", fn);
+		ret = -1;
+		goto done;
+	}
+
+	while ((scn = elf_nextscn(elf, scn))) {
+		const char *sh_name;
+		GElf_Shdr sh;
+
+		if (gelf_getshdr(scn, &sh) != &sh) {
+			fprintf(stderr,
+				"Failed to get section header from %s\n", fn);
+			ret = -1;
+			goto done;
+		}
+
+		sh_name = elf_strptr(elf, ehdr.e_shstrndx, sh.sh_name);
+		if (!strcmp(sh_name, BTF_ELF_SEC)) {
+			ret = 1;
+			goto done;
+		}
+	}
+
+	ret = 0;
+
+done:
+	close(elf_fd);
+	elf_end(elf);
+	return ret;
+}
+
+static int do_test_file(unsigned int test_num)
+{
+	const struct btf_file_test *test = &file_tests[test_num - 1];
+	struct bpf_object *obj = NULL;
+	struct bpf_program *prog;
+	struct bpf_map *map;
+	int err;
+
+	fprintf(stderr, "BTF libbpf test[%u] (%s): ", test_num,
+		test->file);
+
+	err = file_has_btf_elf(test->file);
+	if (err == -1)
+		return err;
+
+	if (err == 0) {
+		fprintf(stderr, "SKIP. No ELF %s found\n", BTF_ELF_SEC);
+		return 0;
+	}
+
+	obj = bpf_object__open(test->file);
+	if (IS_ERR(obj))
+		return PTR_ERR(obj);
+
+	err = bpf_object__btf_fd(obj);
+	if (err == -1) {
+		fprintf(stderr, "bpf_object__btf_fd: -1\n");
+		goto done;
+	}
+
+	prog = bpf_program__next(NULL, obj);
+	if (!prog) {
+		fprintf(stderr, "Cannot find bpf_prog\n");
+		err = -1;
+		goto done;
+	}
+
+	bpf_program__set_type(prog, BPF_PROG_TYPE_TRACEPOINT);
+	err = bpf_object__load(obj);
+	if (err < 0) {
+		fprintf(stderr, "bpf_object__load: %d\n", err);
+		goto done;
+	}
+
+	map = bpf_object__find_map_by_name(obj, "btf_map");
+	if (!map) {
+		fprintf(stderr, "btf_map not found\n");
+		err = -1;
+		goto done;
+	}
+
+	err = (bpf_map__btf_key_id(map) == 0 || bpf_map__btf_value_id(map) == 0)
+		!= test->btf_kv_notfound;
+	if (err) {
+		fprintf(stderr,
+			"btf_kv_notfound:%u btf_key_id:%u btf_value_id:%u\n",
+			test->btf_kv_notfound,
+			bpf_map__btf_key_id(map),
+			bpf_map__btf_value_id(map));
+		goto done;
+	}
+
+	fprintf(stderr, "OK\n");
+
+done:
+	bpf_object__close(obj);
+	return err;
+}
+
+static int test_file(void)
+{
+	unsigned int i;
+	int err = 0;
+
+	if (args.file_test_num)
+		return do_test_file(args.file_test_num);
+
+	for (i = 1; i <= ARRAY_SIZE(file_tests); i++)
+		err |= do_test_file(i);
+
+	return err;
+}
+
+const char *pprint_enum_str[] = {
+	"ENUM_ZERO",
+	"ENUM_ONE",
+	"ENUM_TWO",
+	"ENUM_THREE",
+};
+
+struct pprint_mapv {
+	uint32_t ui32;
+	uint16_t ui16;
+	/* 2 bytes hole */
+	int32_t si32;
+	uint32_t unused_bits2a:2,
+		bits28:28,
+		unused_bits2b:2;
+	union {
+		uint64_t ui64;
+		uint8_t ui8a[8];
+	};
+	enum {
+		ENUM_ZERO,
+		ENUM_ONE,
+		ENUM_TWO,
+		ENUM_THREE,
+	} aenum;
+};
+
+static struct btf_raw_test pprint_test = {
+	.descr = "BTF pretty print test #1",
+	.raw_types = {
+		/* unsighed char */			/* [1] */
+		BTF_TYPE_INT_ENC(NAME_TBD, 0, 0, 8, 1),
+		/* unsigned short */			/* [2] */
+		BTF_TYPE_INT_ENC(NAME_TBD, 0, 0, 16, 2),
+		/* unsigned int */			/* [3] */
+		BTF_TYPE_INT_ENC(NAME_TBD, 0, 0, 32, 4),
+		/* int */				/* [4] */
+		BTF_TYPE_INT_ENC(NAME_TBD, BTF_INT_SIGNED, 0, 32, 4),
+		/* unsigned long long */		/* [5] */
+		BTF_TYPE_INT_ENC(NAME_TBD, 0, 0, 64, 8),
+		/* 2 bits */				/* [6] */
+		BTF_TYPE_INT_ENC(0, 0, 0, 2, 2),
+		/* 28 bits */				/* [7] */
+		BTF_TYPE_INT_ENC(0, 0, 0, 28, 4),
+		/* uint8_t[8] */			/* [8] */
+		BTF_TYPE_ARRAY_ENC(9, 3, 8),
+		/* typedef unsigned char uint8_t */	/* [9] */
+		BTF_TYPEDEF_ENC(NAME_TBD, 1),
+		/* typedef unsigned short uint16_t */	/* [10] */
+		BTF_TYPEDEF_ENC(NAME_TBD, 2),
+		/* typedef unsigned int uint32_t */	/* [11] */
+		BTF_TYPEDEF_ENC(NAME_TBD, 3),
+		/* typedef int int32_t */		/* [12] */
+		BTF_TYPEDEF_ENC(NAME_TBD, 4),
+		/* typedef unsigned long long uint64_t *//* [13] */
+		BTF_TYPEDEF_ENC(NAME_TBD, 5),
+		/* union (anon) */			/* [14] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_UNION, 0, 2), 8),
+		BTF_MEMBER_ENC(NAME_TBD, 13, 0),/* uint64_t ui64; */
+		BTF_MEMBER_ENC(NAME_TBD, 8, 0),	/* uint8_t ui8a[8]; */
+		/* enum (anon) */			/* [15] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_ENUM, 0, 4), 4),
+		BTF_ENUM_ENC(NAME_TBD, 0),
+		BTF_ENUM_ENC(NAME_TBD, 1),
+		BTF_ENUM_ENC(NAME_TBD, 2),
+		BTF_ENUM_ENC(NAME_TBD, 3),
+		/* struct pprint_mapv */		/* [16] */
+		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 8), 28),
+		BTF_MEMBER_ENC(NAME_TBD, 11, 0),	/* uint32_t ui32 */
+		BTF_MEMBER_ENC(NAME_TBD, 10, 32),	/* uint16_t ui16 */
+		BTF_MEMBER_ENC(NAME_TBD, 12, 64),	/* int32_t si32 */
+		BTF_MEMBER_ENC(NAME_TBD, 6, 96),	/* unused_bits2a */
+		BTF_MEMBER_ENC(NAME_TBD, 7, 98),	/* bits28 */
+		BTF_MEMBER_ENC(NAME_TBD, 6, 126),	/* unused_bits2b */
+		BTF_MEMBER_ENC(0, 14, 128),		/* union (anon) */
+		BTF_MEMBER_ENC(NAME_TBD, 15, 192),	/* aenum */
+		BTF_END_RAW,
+	},
+	.str_sec = "\0unsigned char\0unsigned short\0unsigned int\0int\0unsigned long long\0uint8_t\0uint16_t\0uint32_t\0int32_t\0uint64_t\0ui64\0ui8a\0ENUM_ZERO\0ENUM_ONE\0ENUM_TWO\0ENUM_THREE\0pprint_mapv\0ui32\0ui16\0si32\0unused_bits2a\0bits28\0unused_bits2b\0aenum",
+	.str_sec_size = sizeof("\0unsigned char\0unsigned short\0unsigned int\0int\0unsigned long long\0uint8_t\0uint16_t\0uint32_t\0int32_t\0uint64_t\0ui64\0ui8a\0ENUM_ZERO\0ENUM_ONE\0ENUM_TWO\0ENUM_THREE\0pprint_mapv\0ui32\0ui16\0si32\0unused_bits2a\0bits28\0unused_bits2b\0aenum"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "pprint_test",
+	.key_size = sizeof(unsigned int),
+	.value_size = sizeof(struct pprint_mapv),
+	.key_id = 3,	/* unsigned int */
+	.value_id = 16,	/* struct pprint_mapv */
+	.max_entries = 128 * 1024,
+};
+
+static void set_pprint_mapv(struct pprint_mapv *v, uint32_t i)
+{
+	v->ui32 = i;
+	v->si32 = -i;
+	v->unused_bits2a = 3;
+	v->bits28 = i;
+	v->unused_bits2b = 3;
+	v->ui64 = i;
+	v->aenum = i & 0x03;
+}
+
+static int test_pprint(void)
+{
+	const struct btf_raw_test *test = &pprint_test;
+	struct bpf_create_map_attr create_attr = {};
+	int map_fd = -1, btf_fd = -1;
+	struct pprint_mapv mapv = {};
+	unsigned int raw_btf_size;
+	char expected_line[255];
+	FILE *pin_file = NULL;
+	char pin_path[255];
+	size_t line_len = 0;
+	char *line = NULL;
+	unsigned int key;
+	uint8_t *raw_btf;
+	ssize_t nread;
+	int err;
+
+	fprintf(stderr, "%s......", test->descr);
+	raw_btf = btf_raw_create(&hdr_tmpl, test->raw_types,
+				 test->str_sec, test->str_sec_size,
+				 &raw_btf_size);
+
+	if (!raw_btf)
+		return -1;
+
+	*btf_log_buf = '\0';
+	btf_fd = bpf_load_btf(raw_btf, raw_btf_size,
+			      btf_log_buf, BTF_LOG_BUF_SIZE,
+			      args.always_log);
+	free(raw_btf);
+
+	if (btf_fd == -1) {
+		err = -1;
+		fprintf(stderr, "bpf_load_btf: %s(%d)\n",
+			strerror(errno), errno);
+		goto done;
+	}
+
+	create_attr.name = test->map_name;
+	create_attr.map_type = test->map_type;
+	create_attr.key_size = test->key_size;
+	create_attr.value_size = test->value_size;
+	create_attr.max_entries = test->max_entries;
+	create_attr.btf_fd = btf_fd;
+	create_attr.btf_key_id = test->key_id;
+	create_attr.btf_value_id = test->value_id;
+
+	map_fd = bpf_create_map_xattr(&create_attr);
+	if (map_fd == -1) {
+		err = -1;
+		fprintf(stderr, "bpf_creat_map_btf: %s(%d)\n",
+			strerror(errno), errno);
+		goto done;
+	}
+
+	if (snprintf(pin_path, sizeof(pin_path), "%s/%s",
+		     "/sys/fs/bpf", test->map_name) == sizeof(pin_path)) {
+		err = -1;
+		fprintf(stderr, "pin_path is too long\n");
+		goto done;
+	}
+
+	err = bpf_obj_pin(map_fd, pin_path);
+	if (err) {
+		fprintf(stderr, "Cannot pin to %s. %s(%d).\n", pin_path,
+			strerror(errno), errno);
+		goto done;
+	}
+
+	for (key = 0; key < test->max_entries; key++) {
+		set_pprint_mapv(&mapv, key);
+		bpf_map_update_elem(map_fd, &key, &mapv, 0);
+	}
+
+	pin_file = fopen(pin_path, "r");
+	if (!pin_file) {
+		err = -1;
+		fprintf(stderr, "fopen(%s): %s(%d)\n", pin_path,
+			strerror(errno), errno);
+		goto done;
+	}
+
+	/* Skip lines start with '#' */
+	while ((nread = getline(&line, &line_len, pin_file)) > 0 &&
+	       *line == '#')
+		;
+
+	if (nread <= 0) {
+		err = -1;
+		fprintf(stderr, "Unexpected EOF\n");
+		goto done;
+	}
+
+	key = 0;
+	do {
+		ssize_t nexpected_line;
+
+		set_pprint_mapv(&mapv, key);
+		nexpected_line = snprintf(expected_line, sizeof(expected_line),
+					  "%u: {%u,0,%d,0x%x,0x%x,0x%x,{%lu|[%u,%u,%u,%u,%u,%u,%u,%u]},%s}\n",
+					  key,
+					  mapv.ui32, mapv.si32,
+					  mapv.unused_bits2a, mapv.bits28, mapv.unused_bits2b,
+					  mapv.ui64,
+					  mapv.ui8a[0], mapv.ui8a[1], mapv.ui8a[2], mapv.ui8a[3],
+					  mapv.ui8a[4], mapv.ui8a[5], mapv.ui8a[6], mapv.ui8a[7],
+					  pprint_enum_str[mapv.aenum]);
+
+		if (nexpected_line == sizeof(expected_line)) {
+			err = -1;
+			fprintf(stderr, "expected_line is too long\n");
+			goto done;
+		}
+
+		if (strcmp(expected_line, line)) {
+			err = -1;
+			fprintf(stderr, "unexpected pprint output\n");
+			fprintf(stderr, "expected: %s", expected_line);
+			fprintf(stderr, "    read: %s", line);
+			goto done;
+		}
+
+		nread = getline(&line, &line_len, pin_file);
+	} while (++key < test->max_entries && nread > 0);
+
+	if (key < test->max_entries) {
+		err = -1;
+		fprintf(stderr, "Unexpected EOF\n");
+		goto done;
+	}
+
+	if (nread > 0) {
+		err = -1;
+		fprintf(stderr, "Unexpected extra pprint output: %s\n", line);
+		goto done;
+	}
+
+	err = 0;
+
+done:
+	if (!err)
+		fprintf(stderr, "OK\n");
+	if (*btf_log_buf && (err || args.always_log))
+		fprintf(stderr, "%s\n", btf_log_buf);
+	if (btf_fd != -1)
+		close(btf_fd);
+	if (map_fd != -1)
+		close(map_fd);
+	if (pin_file)
+		fclose(pin_file);
+	unlink(pin_path);
+	free(line);
+
+	return err;
+}
+
+static void usage(const char *cmd)
+{
+	fprintf(stderr, "Usage: %s [-l] [[-r test_num (1 - %zu)] | [-g test_num (1 - %zu)] | [-f test_num (1 - %zu)] | [-p]]\n",
+		cmd, ARRAY_SIZE(raw_tests), ARRAY_SIZE(get_info_tests),
+		ARRAY_SIZE(file_tests));
+}
+
+static int parse_args(int argc, char **argv)
+{
+	const char *optstr = "lpf:r:g:";
+	int opt;
+
+	while ((opt = getopt(argc, argv, optstr)) != -1) {
+		switch (opt) {
+		case 'l':
+			args.always_log = true;
+			break;
+		case 'f':
+			args.file_test_num = atoi(optarg);
+			args.file_test = true;
+			break;
+		case 'r':
+			args.raw_test_num = atoi(optarg);
+			args.raw_test = true;
+			break;
+		case 'g':
+			args.get_info_test_num = atoi(optarg);
+			args.get_info_test = true;
+			break;
+		case 'p':
+			args.pprint_test = true;
+			break;
+		case 'h':
+			usage(argv[0]);
+			exit(0);
+		default:
+				usage(argv[0]);
+				return -1;
+		}
+	}
+
+	if (args.raw_test_num &&
+	    (args.raw_test_num < 1 ||
+	     args.raw_test_num > ARRAY_SIZE(raw_tests))) {
+		fprintf(stderr, "BTF raw test number must be [1 - %zu]\n",
+			ARRAY_SIZE(raw_tests));
+		return -1;
+	}
+
+	if (args.file_test_num &&
+	    (args.file_test_num < 1 ||
+	     args.file_test_num > ARRAY_SIZE(file_tests))) {
+		fprintf(stderr, "BTF file test number must be [1 - %zu]\n",
+			ARRAY_SIZE(file_tests));
+		return -1;
+	}
+
+	if (args.get_info_test_num &&
+	    (args.get_info_test_num < 1 ||
+	     args.get_info_test_num > ARRAY_SIZE(get_info_tests))) {
+		fprintf(stderr, "BTF get info test number must be [1 - %zu]\n",
+			ARRAY_SIZE(get_info_tests));
+		return -1;
+	}
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int err = 0;
+
+	err = parse_args(argc, argv);
+	if (err)
+		return err;
+
+	if (args.always_log)
+		libbpf_set_print(__base_pr, __base_pr, __base_pr);
+
+	if (args.raw_test)
+		err |= test_raw();
+
+	if (args.get_info_test)
+		err |= test_get_info();
+
+	if (args.file_test)
+		err |= test_file();
+
+	if (args.pprint_test)
+		err |= test_pprint();
+
+	if (args.raw_test || args.get_info_test || args.file_test ||
+	    args.pprint_test)
+		return err;
+
+	err |= test_raw();
+	err |= test_get_info();
+	err |= test_file();
+
+	return err;
+}

tools/testing/selftests/bpf/test_btf_haskv.c

+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2018 Facebook */
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+int _version SEC("version") = 1;
+
+struct ipv_counts {
+	unsigned int v4;
+	unsigned int v6;
+};
+
+typedef int btf_map_key;
+typedef struct ipv_counts btf_map_value;
+btf_map_key dumm_key;
+btf_map_value dummy_value;
+
+struct bpf_map_def SEC("maps") btf_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(int),
+	.value_size = sizeof(struct ipv_counts),
+	.max_entries = 4,
+};
+
+struct dummy_tracepoint_args {
+	unsigned long long pad;
+	struct sock *sock;
+};
+
+SEC("dummy_tracepoint")
+int _dummy_tracepoint(struct dummy_tracepoint_args *arg)
+{
+	struct ipv_counts *counts;
+	int key = 0;
+
+	if (!arg->sock)
+		return 0;
+
+	counts = bpf_map_lookup_elem(&btf_map, &key);
+	if (!counts)
+		return 0;
+
+	counts->v6++;
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";

tools/testing/selftests/bpf/test_btf_nokv.c

+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2018 Facebook */
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+int _version SEC("version") = 1;
+
+struct ipv_counts {
+	unsigned int v4;
+	unsigned int v6;
+};
+
+struct bpf_map_def SEC("maps") btf_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(int),
+	.value_size = sizeof(struct ipv_counts),
+	.max_entries = 4,
+};
+
+struct dummy_tracepoint_args {
+	unsigned long long pad;
+	struct sock *sock;
+};
+
+SEC("dummy_tracepoint")
+int _dummy_tracepoint(struct dummy_tracepoint_args *arg)
+{
+	struct ipv_counts *counts;
+	int key = 0;
+
+	if (!arg->sock)
+		return 0;
+
+	counts = bpf_map_lookup_elem(&btf_map, &key);
+	if (!counts)
+		return 0;
+
+	counts->v6++;
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";