Merge branch 'bpf-btf-id'

Martin KaFai Lau says:

====================
This series introduces BTF ID which is exposed through
the new BPF_BTF_GET_FD_BY_ID cmd, new "struct bpf_btf_info"
and new members in the "struct bpf_map_info".

Please see individual patch for details.
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

8 files changed, 563 insertions, 127 deletions

diff --git a/include/linux/btf.h b/include/linux/btf.h
index a966dc6d61ee..e076c4697049 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -44,5 +44,7 @@ const struct btf_type *btf_type_id_size(const struct btf *btf,
 					u32 *ret_size);
 void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
 		       struct seq_file *m);
+int btf_get_fd_by_id(u32 id);
+u32 btf_id(const struct btf *btf);
 
 #endif
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 93d5a4eeec2a..d615c777b573 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -96,6 +96,7 @@ enum bpf_cmd {
 	BPF_PROG_QUERY,
 	BPF_RAW_TRACEPOINT_OPEN,
 	BPF_BTF_LOAD,
+	BPF_BTF_GET_FD_BY_ID,
 };
 
 enum bpf_map_type {
@@ -344,6 +345,7 @@ union bpf_attr {
 			__u32		start_id;
 			__u32		prog_id;
 			__u32		map_id;
+			__u32		btf_id;
 		};
 		__u32		next_id;
 		__u32		open_flags;
@@ -2130,6 +2132,15 @@ struct bpf_map_info {
 	__u32 ifindex;
 	__u64 netns_dev;
 	__u64 netns_ino;
+	__u32 btf_id;
+	__u32 btf_key_id;
+	__u32 btf_value_id;
+} __attribute__((aligned(8)));
+
+struct bpf_btf_info {
+	__aligned_u64 btf;
+	__u32 btf_size;
+	__u32 id;
 } __attribute__((aligned(8)));
 
 /* User bpf_sock_addr struct to access socket fields and sockaddr struct passed
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 22e1046a1a86..ded10ab47b8a 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -11,6 +11,7 @@
 #include <linux/file.h>
 #include <linux/uaccess.h>
 #include <linux/kernel.h>
+#include <linux/idr.h>
 #include <linux/bpf_verifier.h>
 #include <linux/btf.h>
 
@@ -179,6 +180,9 @@
 	     i < btf_type_vlen(struct_type);				\
 	     i++, member++)
 
+static DEFINE_IDR(btf_idr);
+static DEFINE_SPINLOCK(btf_idr_lock);
+
 struct btf {
 	union {
 		struct btf_header *hdr;
@@ -193,6 +197,8 @@ struct btf {
 	u32 types_size;
 	u32 data_size;
 	refcount_t refcnt;
+	u32 id;
+	struct rcu_head rcu;
 };
 
 enum verifier_phase {
@@ -598,6 +604,42 @@ static int btf_add_type(struct btf_verifier_env *env, struct btf_type *t)
 	return 0;
 }
 
+static int btf_alloc_id(struct btf *btf)
+{
+	int id;
+
+	idr_preload(GFP_KERNEL);
+	spin_lock_bh(&btf_idr_lock);
+	id = idr_alloc_cyclic(&btf_idr, btf, 1, INT_MAX, GFP_ATOMIC);
+	if (id > 0)
+		btf->id = id;
+	spin_unlock_bh(&btf_idr_lock);
+	idr_preload_end();
+
+	if (WARN_ON_ONCE(!id))
+		return -ENOSPC;
+
+	return id > 0 ? 0 : id;
+}
+
+static void btf_free_id(struct btf *btf)
+{
+	unsigned long flags;
+
+	/*
+	 * In map-in-map, calling map_delete_elem() on outer
+	 * map will call bpf_map_put on the inner map.
+	 * It will then eventually call btf_free_id()
+	 * on the inner map.  Some of the map_delete_elem()
+	 * implementation may have irq disabled, so
+	 * we need to use the _irqsave() version instead
+	 * of the _bh() version.
+	 */
+	spin_lock_irqsave(&btf_idr_lock, flags);
+	idr_remove(&btf_idr, btf->id);
+	spin_unlock_irqrestore(&btf_idr_lock, flags);
+}
+
 static void btf_free(struct btf *btf)
 {
 	kvfree(btf->types);
@@ -607,15 +649,19 @@ static void btf_free(struct btf *btf)
 	kfree(btf);
 }
 
-static void btf_get(struct btf *btf)
+static void btf_free_rcu(struct rcu_head *rcu)
 {
-	refcount_inc(&btf->refcnt);
+	struct btf *btf = container_of(rcu, struct btf, rcu);
+
+	btf_free(btf);
 }
 
 void btf_put(struct btf *btf)
 {
-	if (btf && refcount_dec_and_test(&btf->refcnt))
-		btf_free(btf);
+	if (btf && refcount_dec_and_test(&btf->refcnt)) {
+		btf_free_id(btf);
+		call_rcu(&btf->rcu, btf_free_rcu);
+	}
 }
 
 static int env_resolve_init(struct btf_verifier_env *env)
@@ -1977,7 +2023,7 @@ static struct btf *btf_parse(void __user *btf_data, u32 btf_data_size,
 
 	if (!err) {
 		btf_verifier_env_free(env);
-		btf_get(btf);
+		refcount_set(&btf->refcnt, 1);
 		return btf;
 	}
 
@@ -2006,10 +2052,15 @@ const struct file_operations btf_fops = {
 	.release	= btf_release,
 };
 
+static int __btf_new_fd(struct btf *btf)
+{
+	return anon_inode_getfd("btf", &btf_fops, btf, O_RDONLY | O_CLOEXEC);
+}
+
 int btf_new_fd(const union bpf_attr *attr)
 {
 	struct btf *btf;
-	int fd;
+	int ret;
 
 	btf = btf_parse(u64_to_user_ptr(attr->btf),
 			attr->btf_size, attr->btf_log_level,
@@ -2018,12 +2069,23 @@ int btf_new_fd(const union bpf_attr *attr)
 	if (IS_ERR(btf))
 		return PTR_ERR(btf);
 
-	fd = anon_inode_getfd("btf", &btf_fops, btf,
-			      O_RDONLY | O_CLOEXEC);
-	if (fd < 0)
+	ret = btf_alloc_id(btf);
+	if (ret) {
+		btf_free(btf);
+		return ret;
+	}
+
+	/*
+	 * The BTF ID is published to the userspace.
+	 * All BTF free must go through call_rcu() from
+	 * now on (i.e. free by calling btf_put()).
+	 */
+
+	ret = __btf_new_fd(btf);
+	if (ret < 0)
 		btf_put(btf);
 
-	return fd;
+	return ret;
 }
 
 struct btf *btf_get_by_fd(int fd)
@@ -2042,7 +2104,7 @@ struct btf *btf_get_by_fd(int fd)
 	}
 
 	btf = f.file->private_data;
-	btf_get(btf);
+	refcount_inc(&btf->refcnt);
 	fdput(f);
 
 	return btf;
@@ -2052,13 +2114,55 @@ 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);
+	struct bpf_btf_info __user *uinfo;
+	struct bpf_btf_info info = {};
+	u32 info_copy, btf_copy;
+	void __user *ubtf;
+	u32 uinfo_len;
+
+	uinfo = u64_to_user_ptr(attr->info.info);
+	uinfo_len = attr->info.info_len;
 
-	if (copy_to_user(udata, btf->data, copy_len) ||
-	    put_user(btf->data_size, &uattr->info.info_len))
+	info_copy = min_t(u32, uinfo_len, sizeof(info));
+	if (copy_from_user(&info, uinfo, info_copy))
+		return -EFAULT;
+
+	info.id = btf->id;
+	ubtf = u64_to_user_ptr(info.btf);
+	btf_copy = min_t(u32, btf->data_size, info.btf_size);
+	if (copy_to_user(ubtf, btf->data, btf_copy))
+		return -EFAULT;
+	info.btf_size = btf->data_size;
+
+	if (copy_to_user(uinfo, &info, info_copy) ||
+	    put_user(info_copy, &uattr->info.info_len))
 		return -EFAULT;
 
 	return 0;
 }
+
+int btf_get_fd_by_id(u32 id)
+{
+	struct btf *btf;
+	int fd;
+
+	rcu_read_lock();
+	btf = idr_find(&btf_idr, id);
+	if (!btf || !refcount_inc_not_zero(&btf->refcnt))
+		btf = ERR_PTR(-ENOENT);
+	rcu_read_unlock();
+
+	if (IS_ERR(btf))
+		return PTR_ERR(btf);
+
+	fd = __btf_new_fd(btf);
+	if (fd < 0)
+		btf_put(btf);
+
+	return fd;
+}
+
+u32 btf_id(const struct btf *btf)
+{
+	return btf->id;
+}
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 9b87198deea2..e2aeb5e89f44 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -252,7 +252,6 @@ 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);
 }
@@ -273,6 +272,7 @@ static void __bpf_map_put(struct bpf_map *map, bool do_idr_lock)
 	if (atomic_dec_and_test(&map->refcnt)) {
 		/* bpf_map_free_id() must be called first */
 		bpf_map_free_id(map, do_idr_lock);
+		btf_put(map->btf);
 		INIT_WORK(&map->work, bpf_map_free_deferred);
 		schedule_work(&map->work);
 	}
@@ -2002,6 +2002,12 @@ static int bpf_map_get_info_by_fd(struct bpf_map *map,
 	info.map_flags = map->map_flags;
 	memcpy(info.name, map->name, sizeof(map->name));
 
+	if (map->btf) {
+		info.btf_id = btf_id(map->btf);
+		info.btf_key_id = map->btf_key_id;
+		info.btf_value_id = map->btf_value_id;
+	}
+
 	if (bpf_map_is_dev_bound(map)) {
 		err = bpf_map_offload_info_fill(&info, map);
 		if (err)
@@ -2015,6 +2021,21 @@ static int bpf_map_get_info_by_fd(struct bpf_map *map,
 	return 0;
 }
 
+static int bpf_btf_get_info_by_fd(struct btf *btf,
+				  const union bpf_attr *attr,
+				  union bpf_attr __user *uattr)
+{
+	struct bpf_btf_info __user *uinfo = u64_to_user_ptr(attr->info.info);
+	u32 info_len = attr->info.info_len;
+	int err;
+
+	err = check_uarg_tail_zero(uinfo, sizeof(*uinfo), info_len);
+	if (err)
+		return err;
+
+	return btf_get_info_by_fd(btf, attr, uattr);
+}
+
 #define BPF_OBJ_GET_INFO_BY_FD_LAST_FIELD info.info
 
 static int bpf_obj_get_info_by_fd(const union bpf_attr *attr,
@@ -2038,7 +2059,7 @@ static int bpf_obj_get_info_by_fd(const union bpf_attr *attr,
 		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);
+		err = bpf_btf_get_info_by_fd(f.file->private_data, attr, uattr);
 	else
 		err = -EINVAL;
 
@@ -2059,6 +2080,19 @@ static int bpf_btf_load(const union bpf_attr *attr)
 	return btf_new_fd(attr);
 }
 
+#define BPF_BTF_GET_FD_BY_ID_LAST_FIELD btf_id
+
+static int bpf_btf_get_fd_by_id(const union bpf_attr *attr)
+{
+	if (CHECK_ATTR(BPF_BTF_GET_FD_BY_ID))
+		return -EINVAL;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	return btf_get_fd_by_id(attr->btf_id);
+}
+
 SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
 {
 	union bpf_attr attr = {};
@@ -2142,6 +2176,9 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
 	case BPF_BTF_LOAD:
 		err = bpf_btf_load(&attr);
 		break;
+	case BPF_BTF_GET_FD_BY_ID:
+		err = bpf_btf_get_fd_by_id(&attr);
+		break;
 	default:
 		err = -EINVAL;
 		break;
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 83a95ae388dd..fff51c187d1e 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -96,6 +96,7 @@ enum bpf_cmd {
 	BPF_PROG_QUERY,
 	BPF_RAW_TRACEPOINT_OPEN,
 	BPF_BTF_LOAD,
+	BPF_BTF_GET_FD_BY_ID,
 };
 
 enum bpf_map_type {
@@ -343,6 +344,7 @@ union bpf_attr {
 			__u32		start_id;
 			__u32		prog_id;
 			__u32		map_id;
+			__u32		btf_id;
 		};
 		__u32		next_id;
 		__u32		open_flags;
@@ -2129,6 +2131,15 @@ struct bpf_map_info {
 	__u32 ifindex;
 	__u64 netns_dev;
 	__u64 netns_ino;
+	__u32 btf_id;
+	__u32 btf_key_id;
+	__u32 btf_value_id;
+} __attribute__((aligned(8)));
+
+struct bpf_btf_info {
+	__aligned_u64 btf;
+	__u32 btf_size;
+	__u32 id;
 } __attribute__((aligned(8)));
 
 /* User bpf_sock_addr struct to access socket fields and sockaddr struct passed
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 76b36cc16e7f..a3a8fb2ac697 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -458,6 +458,16 @@ int bpf_map_get_fd_by_id(__u32 id)
 	return sys_bpf(BPF_MAP_GET_FD_BY_ID, &attr, sizeof(attr));
 }
 
+int bpf_btf_get_fd_by_id(__u32 id)
+{
+	union bpf_attr attr;
+
+	bzero(&attr, sizeof(attr));
+	attr.btf_id = id;
+
+	return sys_bpf(BPF_BTF_GET_FD_BY_ID, &attr, sizeof(attr));
+}
+
 int bpf_obj_get_info_by_fd(int prog_fd, void *info, __u32 *info_len)
 {
 	union bpf_attr attr;
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 553b11ad52b3..fb3a146d92ff 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -98,6 +98,7 @@ int bpf_prog_get_next_id(__u32 start_id, __u32 *next_id);
 int bpf_map_get_next_id(__u32 start_id, __u32 *next_id);
 int bpf_prog_get_fd_by_id(__u32 id);
 int bpf_map_get_fd_by_id(__u32 id);
+int bpf_btf_get_fd_by_id(__u32 id);
 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);
diff --git a/tools/testing/selftests/bpf/test_btf.c b/tools/testing/selftests/bpf/test_btf.c
index 7b39b1f712a1..c8bceae7ec02 100644
--- a/tools/testing/selftests/bpf/test_btf.c
+++ b/tools/testing/selftests/bpf/test_btf.c
@@ -20,6 +20,30 @@
 
 #include "bpf_rlimit.h"
 
+static uint32_t pass_cnt;
+static uint32_t error_cnt;
+static uint32_t skip_cnt;
+
+#define CHECK(condition, format...) ({					\
+	int __ret = !!(condition);					\
+	if (__ret) {							\
+		fprintf(stderr, "%s:%d:FAIL ", __func__, __LINE__);	\
+		fprintf(stderr, format);				\
+	}								\
+	__ret;								\
+})
+
+static int count_result(int err)
+{
+	if (err)
+		error_cnt++;
+	else
+		pass_cnt++;
+
+	fprintf(stderr, "\n");
+	return err;
+}
+
 #define min(a, b) ((a) < (b) ? (a) : (b))
 #define __printf(a, b)	__attribute__((format(printf, a, b)))
 
@@ -894,17 +918,13 @@ static void *btf_raw_create(const struct btf_header *hdr,
 	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");
+	if (CHECK(type_sec_size < 0, "Cannot get nr_raw_types"))
 		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");
+	if (CHECK(!raw_btf, "Cannot allocate memory for raw_btf"))
 		return NULL;
-	}
 
 	/* Copy header */
 	memcpy(raw_btf, hdr, sizeof(*hdr));
@@ -915,8 +935,7 @@ static void *btf_raw_create(const struct btf_header *hdr,
 	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");
+			if (CHECK(!next_str, "Error in getting next_str")) {
 				free(raw_btf);
 				return NULL;
 			}
@@ -973,9 +992,8 @@ static int do_test_raw(unsigned int test_num)
 	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);
+	CHECK(err, "btf_fd:%d test->btf_load_err:%u",
+	      btf_fd, test->btf_load_err);
 
 	if (err || btf_fd == -1)
 		goto done;
@@ -992,16 +1010,15 @@ static int do_test_raw(unsigned int test_num)
 	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);
+	CHECK(err, "map_fd:%d test->map_create_err:%u",
+	      map_fd, test->map_create_err);
 
 done:
 	if (!err)
-		fprintf(stderr, "OK\n");
+		fprintf(stderr, "OK");
 
 	if (*btf_log_buf && (err || args.always_log))
-		fprintf(stderr, "%s\n", btf_log_buf);
+		fprintf(stderr, "\n%s", btf_log_buf);
 
 	if (btf_fd != -1)
 		close(btf_fd);
@@ -1017,10 +1034,10 @@ static int test_raw(void)
 	int err = 0;
 
 	if (args.raw_test_num)
-		return do_test_raw(args.raw_test_num);
+		return count_result(do_test_raw(args.raw_test_num));
 
 	for (i = 1; i <= ARRAY_SIZE(raw_tests); i++)
-		err |= do_test_raw(i);
+		err |= count_result(do_test_raw(i));
 
 	return err;
 }
@@ -1030,9 +1047,13 @@ struct btf_get_info_test {
 	const char *str_sec;
 	__u32 raw_types[MAX_NR_RAW_TYPES];
 	__u32 str_sec_size;
-	int info_size_delta;
+	int btf_size_delta;
+	int (*special_test)(unsigned int test_num);
 };
 
+static int test_big_btf_info(unsigned int test_num);
+static int test_btf_id(unsigned int test_num);
+
 const struct btf_get_info_test get_info_tests[] = {
 {
 	.descr = "== raw_btf_size+1",
@@ -1043,7 +1064,7 @@ const struct btf_get_info_test get_info_tests[] = {
 	},
 	.str_sec = "",
 	.str_sec_size = sizeof(""),
-	.info_size_delta = 1,
+	.btf_size_delta = 1,
 },
 {
 	.descr = "== raw_btf_size-3",
@@ -1054,20 +1075,274 @@ const struct btf_get_info_test get_info_tests[] = {
 	},
 	.str_sec = "",
 	.str_sec_size = sizeof(""),
-	.info_size_delta = -3,
+	.btf_size_delta = -3,
+},
+{
+	.descr = "Large bpf_btf_info",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "",
+	.str_sec_size = sizeof(""),
+	.special_test = test_big_btf_info,
+},
+{
+	.descr = "BTF ID",
+	.raw_types = {
+		/* int */				/* [1] */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),
+		/* unsigned int */			/* [2] */
+		BTF_TYPE_INT_ENC(0, 0, 0, 32, 4),
+		BTF_END_RAW,
+	},
+	.str_sec = "",
+	.str_sec_size = sizeof(""),
+	.special_test = test_btf_id,
 },
 };
 
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+	return (__u64)(unsigned long)ptr;
+}
+
+static int test_big_btf_info(unsigned int test_num)
+{
+	const struct btf_get_info_test *test = &get_info_tests[test_num - 1];
+	uint8_t *raw_btf = NULL, *user_btf = NULL;
+	unsigned int raw_btf_size;
+	struct {
+		struct bpf_btf_info info;
+		uint64_t garbage;
+	} info_garbage;
+	struct bpf_btf_info *info;
+	int btf_fd = -1, err;
+	uint32_t info_len;
+
+	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 (CHECK(!user_btf, "!user_btf")) {
+		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 (CHECK(btf_fd == -1, "errno:%d", errno)) {
+		err = -1;
+		goto done;
+	}
+
+	/*
+	 * GET_INFO should error out if the userspace info
+	 * has non zero tailing bytes.
+	 */
+	info = &info_garbage.info;
+	memset(info, 0, sizeof(*info));
+	info_garbage.garbage = 0xdeadbeef;
+	info_len = sizeof(info_garbage);
+	info->btf = ptr_to_u64(user_btf);
+	info->btf_size = raw_btf_size;
+
+	err = bpf_obj_get_info_by_fd(btf_fd, info, &info_len);
+	if (CHECK(!err, "!err")) {
+		err = -1;
+		goto done;
+	}
+
+	/*
+	 * GET_INFO should succeed even info_len is larger than
+	 * the kernel supported as long as tailing bytes are zero.
+	 * The kernel supported info len should also be returned
+	 * to userspace.
+	 */
+	info_garbage.garbage = 0;
+	err = bpf_obj_get_info_by_fd(btf_fd, info, &info_len);
+	if (CHECK(err || info_len != sizeof(*info),
+		  "err:%d errno:%d info_len:%u sizeof(*info):%lu",
+		  err, errno, info_len, sizeof(*info))) {
+		err = -1;
+		goto done;
+	}
+
+	fprintf(stderr, "OK");
+
+done:
+	if (*btf_log_buf && (err || args.always_log))
+		fprintf(stderr, "\n%s", btf_log_buf);
+
+	free(raw_btf);
+	free(user_btf);
+
+	if (btf_fd != -1)
+		close(btf_fd);
+
+	return err;
+}
+
+static int test_btf_id(unsigned int test_num)
+{
+	const struct btf_get_info_test *test = &get_info_tests[test_num - 1];
+	struct bpf_create_map_attr create_attr = {};
+	uint8_t *raw_btf = NULL, *user_btf[2] = {};
+	int btf_fd[2] = {-1, -1}, map_fd = -1;
+	struct bpf_map_info map_info = {};
+	struct bpf_btf_info info[2] = {};
+	unsigned int raw_btf_size;
+	uint32_t info_len;
+	int err, i, ret;
+
+	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';
+
+	for (i = 0; i < 2; i++) {
+		user_btf[i] = malloc(raw_btf_size);
+		if (CHECK(!user_btf[i], "!user_btf[%d]", i)) {
+			err = -1;
+			goto done;
+		}
+		info[i].btf = ptr_to_u64(user_btf[i]);
+		info[i].btf_size = raw_btf_size;
+	}
+
+	btf_fd[0] = bpf_load_btf(raw_btf, raw_btf_size,
+				 btf_log_buf, BTF_LOG_BUF_SIZE,
+				 args.always_log);
+	if (CHECK(btf_fd[0] == -1, "errno:%d", errno)) {
+		err = -1;
+		goto done;
+	}
+
+	/* Test BPF_OBJ_GET_INFO_BY_ID on btf_id */
+	info_len = sizeof(info[0]);
+	err = bpf_obj_get_info_by_fd(btf_fd[0], &info[0], &info_len);
+	if (CHECK(err, "errno:%d", errno)) {
+		err = -1;
+		goto done;
+	}
+
+	btf_fd[1] = bpf_btf_get_fd_by_id(info[0].id);
+	if (CHECK(btf_fd[1] == -1, "errno:%d", errno)) {
+		err = -1;
+		goto done;
+	}
+
+	ret = 0;
+	err = bpf_obj_get_info_by_fd(btf_fd[1], &info[1], &info_len);
+	if (CHECK(err || info[0].id != info[1].id ||
+		  info[0].btf_size != info[1].btf_size ||
+		  (ret = memcmp(user_btf[0], user_btf[1], info[0].btf_size)),
+		  "err:%d errno:%d id0:%u id1:%u btf_size0:%u btf_size1:%u memcmp:%d",
+		  err, errno, info[0].id, info[1].id,
+		  info[0].btf_size, info[1].btf_size, ret)) {
+		err = -1;
+		goto done;
+	}
+
+	/* Test btf members in struct bpf_map_info */
+	create_attr.name = "test_btf_id";
+	create_attr.map_type = BPF_MAP_TYPE_ARRAY;
+	create_attr.key_size = sizeof(int);
+	create_attr.value_size = sizeof(unsigned int);
+	create_attr.max_entries = 4;
+	create_attr.btf_fd = btf_fd[0];
+	create_attr.btf_key_id = 1;
+	create_attr.btf_value_id = 2;
+
+	map_fd = bpf_create_map_xattr(&create_attr);
+	if (CHECK(map_fd == -1, "errno:%d", errno)) {
+		err = -1;
+		goto done;
+	}
+
+	info_len = sizeof(map_info);
+	err = bpf_obj_get_info_by_fd(map_fd, &map_info, &info_len);
+	if (CHECK(err || map_info.btf_id != info[0].id ||
+		  map_info.btf_key_id != 1 || map_info.btf_value_id != 2,
+		  "err:%d errno:%d info.id:%u btf_id:%u btf_key_id:%u btf_value_id:%u",
+		  err, errno, info[0].id, map_info.btf_id, map_info.btf_key_id,
+		  map_info.btf_value_id)) {
+		err = -1;
+		goto done;
+	}
+
+	for (i = 0; i < 2; i++) {
+		close(btf_fd[i]);
+		btf_fd[i] = -1;
+	}
+
+	/* Test BTF ID is removed from the kernel */
+	btf_fd[0] = bpf_btf_get_fd_by_id(map_info.btf_id);
+	if (CHECK(btf_fd[0] == -1, "errno:%d", errno)) {
+		err = -1;
+		goto done;
+	}
+	close(btf_fd[0]);
+	btf_fd[0] = -1;
+
+	/* The map holds the last ref to BTF and its btf_id */
+	close(map_fd);
+	map_fd = -1;
+	btf_fd[0] = bpf_btf_get_fd_by_id(map_info.btf_id);
+	if (CHECK(btf_fd[0] != -1, "BTF lingers")) {
+		err = -1;
+		goto done;
+	}
+
+	fprintf(stderr, "OK");
+
+done:
+	if (*btf_log_buf && (err || args.always_log))
+		fprintf(stderr, "\n%s", btf_log_buf);
+
+	free(raw_btf);
+	if (map_fd != -1)
+		close(map_fd);
+	for (i = 0; i < 2; i++) {
+		free(user_btf[i]);
+		if (btf_fd[i] != -1)
+			close(btf_fd[i]);
+	}
+
+	return err;
+}
+
 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;
+	struct bpf_btf_info info = {};
+	int btf_fd = -1, err, ret;
+	uint32_t info_len;
 
-	fprintf(stderr, "BTF GET_INFO_BY_ID test[%u] (%s): ",
+	fprintf(stderr, "BTF GET_INFO test[%u] (%s): ",
 		test_num, test->descr);
 
+	if (test->special_test)
+		return test->special_test(test_num);
+
 	raw_btf = btf_raw_create(&hdr_tmpl,
 				 test->raw_types,
 				 test->str_sec,
@@ -1080,8 +1355,7 @@ static int do_test_get_info(unsigned int test_num)
 	*btf_log_buf = '\0';
 
 	user_btf = malloc(raw_btf_size);
-	if (!user_btf) {
-		fprintf(stderr, "Cannot allocate memory for user_btf\n");
+	if (CHECK(!user_btf, "!user_btf")) {
 		err = -1;
 		goto done;
 	}
@@ -1089,45 +1363,48 @@ static int do_test_get_info(unsigned int test_num)
 	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);
+	if (CHECK(btf_fd == -1, "errno:%d", errno)) {
 		err = -1;
 		goto done;
 	}
 
-	user_btf_size = (int)raw_btf_size + test->info_size_delta;
+	user_btf_size = (int)raw_btf_size + test->btf_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));
+	info_len = sizeof(info);
+	info.btf = ptr_to_u64(user_btf);
+	info.btf_size = user_btf_size;
+
+	ret = 0;
+	err = bpf_obj_get_info_by_fd(btf_fd, &info, &info_len);
+	if (CHECK(err || !info.id || info_len != sizeof(info) ||
+		  info.btf_size != raw_btf_size ||
+		  (ret = memcmp(raw_btf, user_btf, expected_nbytes)),
+		  "err:%d errno:%d info.id:%u info_len:%u sizeof(info):%lu raw_btf_size:%u info.btf_size:%u expected_nbytes:%u memcmp:%d",
+		  err, errno, info.id, info_len, sizeof(info),
+		  raw_btf_size, info.btf_size, expected_nbytes, ret)) {
 		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");
+		if (CHECK(user_btf[expected_nbytes++] != 0xff,
+			  "user_btf[%u]:%x != 0xff", expected_nbytes - 1,
+			  user_btf[expected_nbytes - 1])) {
 			err = -1;
 			goto done;
 		}
 	}
 
-	fprintf(stderr, "OK\n");
+	fprintf(stderr, "OK");
 
 done:
 	if (*btf_log_buf && (err || args.always_log))
-		fprintf(stderr, "%s\n", btf_log_buf);
+		fprintf(stderr, "\n%s", btf_log_buf);
 
 	free(raw_btf);
 	free(user_btf);
@@ -1144,10 +1421,10 @@ static int test_get_info(void)
 	int err = 0;
 
 	if (args.get_info_test_num)
-		return do_test_get_info(args.get_info_test_num);
+		return count_result(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);
+		err |= count_result(do_test_get_info(i));
 
 	return err;
 }
@@ -1175,28 +1452,21 @@ static int file_has_btf_elf(const char *fn)
 	Elf *elf;
 	int ret;
 
-	if (elf_version(EV_CURRENT) == EV_NONE) {
-		fprintf(stderr, "Failed to init libelf\n");
+	if (CHECK(elf_version(EV_CURRENT) == EV_NONE,
+		  "elf_version(EV_CURRENT) == EV_NONE"))
 		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);
+	if (CHECK(elf_fd == -1, "open(%s): errno:%d", fn, 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()));
+	if (CHECK(!elf, "elf_begin(%s): %s", fn, elf_errmsg(elf_errno()))) {
 		ret = -1;
 		goto done;
 	}
 
-	if (!gelf_getehdr(elf, &ehdr)) {
-		fprintf(stderr, "Failed to get EHDR from %s\n", fn);
+	if (CHECK(!gelf_getehdr(elf, &ehdr), "!gelf_getehdr(%s)", fn)) {
 		ret = -1;
 		goto done;
 	}
@@ -1205,9 +1475,8 @@ static int file_has_btf_elf(const char *fn)
 		const char *sh_name;
 		GElf_Shdr sh;
 
-		if (gelf_getshdr(scn, &sh) != &sh) {
-			fprintf(stderr,
-				"Failed to get section header from %s\n", fn);
+		if (CHECK(gelf_getshdr(scn, &sh) != &sh,
+			  "file:%s gelf_getshdr != &sh", fn)) {
 			ret = -1;
 			goto done;
 		}
@@ -1243,53 +1512,44 @@ static int do_test_file(unsigned int test_num)
 		return err;
 
 	if (err == 0) {
-		fprintf(stderr, "SKIP. No ELF %s found\n", BTF_ELF_SEC);
+		fprintf(stderr, "SKIP. No ELF %s found", BTF_ELF_SEC);
+		skip_cnt++;
 		return 0;
 	}
 
 	obj = bpf_object__open(test->file);
-	if (IS_ERR(obj))
+	if (CHECK(IS_ERR(obj), "obj: %ld", PTR_ERR(obj)))
 		return PTR_ERR(obj);
 
 	err = bpf_object__btf_fd(obj);
-	if (err == -1) {
-		fprintf(stderr, "bpf_object__btf_fd: -1\n");
+	if (CHECK(err == -1, "bpf_object__btf_fd: -1"))
 		goto done;
-	}
 
 	prog = bpf_program__next(NULL, obj);
-	if (!prog) {
-		fprintf(stderr, "Cannot find bpf_prog\n");
+	if (CHECK(!prog, "Cannot find bpf_prog")) {
 		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);
+	if (CHECK(err < 0, "bpf_object__load: %d", err))
 		goto done;
-	}
 
 	map = bpf_object__find_map_by_name(obj, "btf_map");
-	if (!map) {
-		fprintf(stderr, "btf_map not found\n");
+	if (CHECK(!map, "btf_map not found")) {
 		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));
+	if (CHECK(err, "btf_key_id:%u btf_value_id:%u test->btf_kv_notfound:%u",
+		  bpf_map__btf_key_id(map), bpf_map__btf_value_id(map),
+		  test->btf_kv_notfound))
 		goto done;
-	}
 
-	fprintf(stderr, "OK\n");
+	fprintf(stderr, "OK");
 
 done:
 	bpf_object__close(obj);
@@ -1302,10 +1562,10 @@ static int test_file(void)
 	int err = 0;
 
 	if (args.file_test_num)
-		return do_test_file(args.file_test_num);
+		return count_result(do_test_file(args.file_test_num));
 
 	for (i = 1; i <= ARRAY_SIZE(file_tests); i++)
-		err |= do_test_file(i);
+		err |= count_result(do_test_file(i));
 
 	return err;
 }
@@ -1425,7 +1685,7 @@ static int test_pprint(void)
 	unsigned int key;
 	uint8_t *raw_btf;
 	ssize_t nread;
-	int err;
+	int err, ret;
 
 	fprintf(stderr, "%s......", test->descr);
 	raw_btf = btf_raw_create(&hdr_tmpl, test->raw_types,
@@ -1441,10 +1701,8 @@ static int test_pprint(void)
 			      args.always_log);
 	free(raw_btf);
 
-	if (btf_fd == -1) {
+	if (CHECK(btf_fd == -1, "errno:%d", errno)) {
 		err = -1;
-		fprintf(stderr, "bpf_load_btf: %s(%d)\n",
-			strerror(errno), errno);
 		goto done;
 	}
 
@@ -1458,26 +1716,23 @@ static int test_pprint(void)
 	create_attr.btf_value_id = test->value_id;
 
 	map_fd = bpf_create_map_xattr(&create_attr);
-	if (map_fd == -1) {
+	if (CHECK(map_fd == -1, "errno:%d", errno)) {
 		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)) {
+	ret = snprintf(pin_path, sizeof(pin_path), "%s/%s",
+		       "/sys/fs/bpf", test->map_name);
+
+	if (CHECK(ret == sizeof(pin_path), "pin_path %s/%s is too long",
+		  "/sys/fs/bpf", test->map_name)) {
 		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);
+	if (CHECK(err, "bpf_obj_pin(%s): errno:%d.", pin_path, errno))
 		goto done;
-	}
 
 	for (key = 0; key < test->max_entries; key++) {
 		set_pprint_mapv(&mapv, key);
@@ -1485,10 +1740,8 @@ static int test_pprint(void)
 	}
 
 	pin_file = fopen(pin_path, "r");
-	if (!pin_file) {
+	if (CHECK(!pin_file, "fopen(%s): errno:%d", pin_path, errno)) {
 		err = -1;
-		fprintf(stderr, "fopen(%s): %s(%d)\n", pin_path,
-			strerror(errno), errno);
 		goto done;
 	}
 
@@ -1497,9 +1750,8 @@ static int test_pprint(void)
 	       *line == '#')
 		;
 
-	if (nread <= 0) {
+	if (CHECK(nread <= 0, "Unexpected EOF")) {
 		err = -1;
-		fprintf(stderr, "Unexpected EOF\n");
 		goto done;
 	}
 
@@ -1518,9 +1770,9 @@ static int test_pprint(void)
 					  mapv.ui8a[4], mapv.ui8a[5], mapv.ui8a[6], mapv.ui8a[7],
 					  pprint_enum_str[mapv.aenum]);
 
-		if (nexpected_line == sizeof(expected_line)) {
+		if (CHECK(nexpected_line == sizeof(expected_line),
+			  "expected_line is too long")) {
 			err = -1;
-			fprintf(stderr, "expected_line is too long\n");
 			goto done;
 		}
 
@@ -1535,15 +1787,15 @@ static int test_pprint(void)
 		nread = getline(&line, &line_len, pin_file);
 	} while (++key < test->max_entries && nread > 0);
 
-	if (key < test->max_entries) {
+	if (CHECK(key < test->max_entries,
+		  "Unexpected EOF. key:%u test->max_entries:%u",
+		  key, test->max_entries)) {
 		err = -1;
-		fprintf(stderr, "Unexpected EOF\n");
 		goto done;
 	}
 
-	if (nread > 0) {
+	if (CHECK(nread > 0, "Unexpected extra pprint output: %s", line)) {
 		err = -1;
-		fprintf(stderr, "Unexpected extra pprint output: %s\n", line);
 		goto done;
 	}
 
@@ -1551,9 +1803,9 @@ static int test_pprint(void)
 
 done:
 	if (!err)
-		fprintf(stderr, "OK\n");
+		fprintf(stderr, "OK");
 	if (*btf_log_buf && (err || args.always_log))
-		fprintf(stderr, "%s\n", btf_log_buf);
+		fprintf(stderr, "\n%s", btf_log_buf);
 	if (btf_fd != -1)
 		close(btf_fd);
 	if (map_fd != -1)
@@ -1634,6 +1886,12 @@ static int parse_args(int argc, char **argv)
 	return 0;
 }
 
+static void print_summary(void)
+{
+	fprintf(stderr, "PASS:%u SKIP:%u FAIL:%u\n",
+		pass_cnt - skip_cnt, skip_cnt, error_cnt);
+}
+
 int main(int argc, char **argv)
 {
 	int err = 0;
@@ -1655,15 +1913,17 @@ int main(int argc, char **argv)
 		err |= test_file();
 
 	if (args.pprint_test)
-		err |= test_pprint();
+		err |= count_result(test_pprint());
 
 	if (args.raw_test || args.get_info_test || args.file_test ||
 	    args.pprint_test)
-		return err;
+		goto done;
 
 	err |= test_raw();
 	err |= test_get_info();
 	err |= test_file();
 
+done:
+	print_summary();
 	return err;
 }