[PATCH bpf 0/3] Introduce BPF_ANNOTATE_KV_PAIR

[PATCH bpf 0/3] Introduce BPF_ANNOTATE_KV_PAIR

[Martin KaFai Lau]

The series allows the BPF loader to figure out
the btf_key_id and btf_value_id from a map's name
by using BPF_ANNOTATE_KV_PAIR.  It also removes
the old 'typedef' way which requires two separate
typedefs (one for the key and one for the value).

By doing this, iproute2 and libbpf have one
consistent way to figure out the btf_key_type_id and
btf_value_type_id for a map.

The first two patches are some prep/cleanup works.
The last patch introduces BPF_ANNOTATE_KV_PAIR.

Martin KaFai Lau (3):
  bpf: btf: Sync uapi btf.h to tools
  bpf: Replace [u]int32_t and [u]int64_t in libbpf
  bpf: Introduce BPF_ANNOTATE_KV_PAIR

 tools/include/uapi/linux/btf.h               |  2 +-
 tools/lib/bpf/btf.c                          | 36 +++++----
 tools/lib/bpf/btf.h                          |  9 ++-
 tools/lib/bpf/libbpf.c                       | 81 +++++++++++---------
 tools/lib/bpf/libbpf.h                       |  4 +-
 tools/testing/selftests/bpf/bpf_helpers.h    |  9 +++
 tools/testing/selftests/bpf/test_btf_haskv.c |  7 +-
 7 files changed, 84 insertions(+), 64 deletions(-)

-- 
2.17.1

[PATCH bpf 1/3] bpf: btf: Sync uapi btf.h to tools

[Martin KaFai Lau]

This patch sync the uapi btf.h to tools/

Fixes: 36fc3c8c282c bpf: btf: Clean up BTF_INT_BITS() in uapi btf.h
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
---
 tools/include/uapi/linux/btf.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/include/uapi/linux/btf.h b/tools/include/uapi/linux/btf.h
index 0b5ddbe135a4..972265f32871 100644
--- a/tools/include/uapi/linux/btf.h
+++ b/tools/include/uapi/linux/btf.h
@@ -76,7 +76,7 @@ struct btf_type {
  */
 #define BTF_INT_ENCODING(VAL)	(((VAL) & 0x0f000000) >> 24)
 #define BTF_INT_OFFSET(VAL)	(((VAL  & 0x00ff0000)) >> 16)
-#define BTF_INT_BITS(VAL)	((VAL)  & 0x0000ffff)
+#define BTF_INT_BITS(VAL)	((VAL)  & 0x000000ff)
 
 /* Attributes stored in the BTF_INT_ENCODING */
 #define BTF_INT_SIGNED	(1 << 0)
-- 
2.17.1

[PATCH bpf 2/3] bpf: Replace [u]int32_t and [u]int64_t in libbpf

[Martin KaFai Lau]

This patch replaces [u]int32_t and [u]int64_t usage with
__[su]32 and __[su]64.  The same change goes for [u]int16_t
and [u]int8_t.

Fixes: 8a138aed4a80 ("bpf: btf: Add BTF support to libbpf")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
---
 tools/lib/bpf/btf.c    | 28 +++++++++++++---------------
 tools/lib/bpf/btf.h    |  8 ++++----
 tools/lib/bpf/libbpf.c | 12 ++++++------
 tools/lib/bpf/libbpf.h |  4 ++--
 4 files changed, 25 insertions(+), 27 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 8c54a4b6f187..ce77b5b57912 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -2,7 +2,6 @@
 /* Copyright (c) 2018 Facebook */
 
 #include <stdlib.h>
-#include <stdint.h>
 #include <string.h>
 #include <unistd.h>
 #include <errno.h>
@@ -27,13 +26,13 @@ struct btf {
 	struct btf_type **types;
 	const char *strings;
 	void *nohdr_data;
-	uint32_t nr_types;
-	uint32_t types_size;
-	uint32_t data_size;
+	__u32 nr_types;
+	__u32 types_size;
+	__u32 data_size;
 	int fd;
 };
 
-static const char *btf_name_by_offset(const struct btf *btf, uint32_t offset)
+static const char *btf_name_by_offset(const struct btf *btf, __u32 offset)
 {
 	if (offset < btf->hdr->str_len)
 		return &btf->strings[offset];
@@ -151,7 +150,7 @@ static int btf_parse_type_sec(struct btf *btf, btf_print_fn_t err_log)
 
 	while (next_type < end_type) {
 		struct btf_type *t = next_type;
-		uint16_t vlen = BTF_INFO_VLEN(t->info);
+		__u16 vlen = BTF_INFO_VLEN(t->info);
 		int err;
 
 		next_type += sizeof(*t);
@@ -191,7 +190,7 @@ static int btf_parse_type_sec(struct btf *btf, btf_print_fn_t err_log)
 }
 
 static const struct btf_type *btf_type_by_id(const struct btf *btf,
-					     uint32_t type_id)
+					     __u32 type_id)
 {
 	if (type_id > btf->nr_types)
 		return NULL;
@@ -226,12 +225,12 @@ static int64_t btf_type_size(const struct btf_type *t)
 
 #define MAX_RESOLVE_DEPTH 32
 
-int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id)
+__s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
 {
 	const struct btf_array *array;
 	const struct btf_type *t;
-	uint32_t nelems = 1;
-	int64_t size = -1;
+	__u32 nelems = 1;
+	__s64 size = -1;
 	int i;
 
 	t = btf_type_by_id(btf, type_id);
@@ -271,9 +270,9 @@ int64_t btf__resolve_size(const struct btf *btf, uint32_t type_id)
 	return nelems * size;
 }
 
-int32_t btf__find_by_name(const struct btf *btf, const char *type_name)
+__s32 btf__find_by_name(const struct btf *btf, const char *type_name)
 {
-	uint32_t i;
+	__u32 i;
 
 	if (!strcmp(type_name, "void"))
 		return 0;
@@ -302,10 +301,9 @@ void btf__free(struct btf *btf)
 	free(btf);
 }
 
-struct btf *btf__new(uint8_t *data, uint32_t size,
-		     btf_print_fn_t err_log)
+struct btf *btf__new(__u8 *data, __u32 size, btf_print_fn_t err_log)
 {
-	uint32_t log_buf_size = 0;
+	__u32 log_buf_size = 0;
 	char *log_buf = NULL;
 	struct btf *btf;
 	int err;
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 74bb344035bb..ed3a84370ccc 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -4,7 +4,7 @@
 #ifndef __BPF_BTF_H
 #define __BPF_BTF_H
 
-#include <stdint.h>
+#include <linux/types.h>
 
 #define BTF_ELF_SEC ".BTF"
 
@@ -14,9 +14,9 @@ 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);
+struct btf *btf__new(__u8 *data, __u32 size, btf_print_fn_t err_log);
+__s32 btf__find_by_name(const struct btf *btf, const char *type_name);
+__s64 btf__resolve_size(const struct btf *btf, __u32 type_id);
 int btf__fd(const struct btf *btf);
 
 #endif
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index a1e96b5de5ff..6deb4fe4fffe 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -216,8 +216,8 @@ struct bpf_map {
 	size_t offset;
 	int map_ifindex;
 	struct bpf_map_def def;
-	uint32_t btf_key_type_id;
-	uint32_t btf_value_type_id;
+	__u32 btf_key_type_id;
+	__u32 btf_value_type_id;
 	void *priv;
 	bpf_map_clear_priv_t clear_priv;
 };
@@ -1016,8 +1016,8 @@ 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;
+	__s64 key_size, value_size;
+	__s32 key_id, value_id;
 	char name[max_name];
 
 	/* Find key type by name from BTF */
@@ -2089,12 +2089,12 @@ const char *bpf_map__name(struct bpf_map *map)
 	return map ? map->name : NULL;
 }
 
-uint32_t bpf_map__btf_key_type_id(const struct bpf_map *map)
+__u32 bpf_map__btf_key_type_id(const struct bpf_map *map)
 {
 	return map ? map->btf_key_type_id : 0;
 }
 
-uint32_t bpf_map__btf_value_type_id(const struct bpf_map *map)
+__u32 bpf_map__btf_value_type_id(const struct bpf_map *map)
 {
 	return map ? map->btf_value_type_id : 0;
 }
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 09976531aa74..b33ae02f7d0e 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -244,8 +244,8 @@ 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_type_id(const struct bpf_map *map);
-uint32_t bpf_map__btf_value_type_id(const struct bpf_map *map);
+__u32 bpf_map__btf_key_type_id(const struct bpf_map *map);
+__u32 bpf_map__btf_value_type_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,
-- 
2.17.1

[PATCH bpf 3/3] bpf: Introduce BPF_ANNOTATE_KV_PAIR

[Martin KaFai Lau]

This patch introduces BPF_ANNOTATE_KV_PAIR to signal the
bpf loader about the btf key_type and value_type of a bpf map.
Please refer to the changes in test_btf_haskv.c for its usage.
Both iproute2 and libbpf loader will then have the same
convention to find out the map's btf_key_type_id and
btf_value_type_id from a map's name.

Fixes: 8a138aed4a80 ("bpf: btf: Add BTF support to libbpf")
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
---
 tools/lib/bpf/btf.c                          |  8 +++
 tools/lib/bpf/btf.h                          |  1 +
 tools/lib/bpf/libbpf.c                       | 71 +++++++++++---------
 tools/testing/selftests/bpf/bpf_helpers.h    |  9 +++
 tools/testing/selftests/bpf/test_btf_haskv.c |  7 +-
 5 files changed, 59 insertions(+), 37 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index ce77b5b57912..748f0b11361d 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -288,6 +288,14 @@ __s32 btf__find_by_name(const struct btf *btf, const char *type_name)
 	return -ENOENT;
 }
 
+const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 id)
+{
+	if (!id || id > btf->nr_types)
+		return ERR_PTR(-EINVAL);
+
+	return btf->types[id];
+}
+
 void btf__free(struct btf *btf)
 {
 	if (!btf)
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index ed3a84370ccc..38ebf66613e4 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -16,6 +16,7 @@ typedef int (*btf_print_fn_t)(const char *, ...)
 void btf__free(struct btf *btf);
 struct btf *btf__new(__u8 *data, __u32 size, btf_print_fn_t err_log);
 __s32 btf__find_by_name(const struct btf *btf, const char *type_name);
+const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 id);
 __s64 btf__resolve_size(const struct btf *btf, __u32 type_id);
 int btf__fd(const struct btf *btf);
 
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 6deb4fe4fffe..5ff7755efa6b 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -36,6 +36,7 @@
 #include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/bpf.h>
+#include <linux/btf.h>
 #include <linux/list.h>
 #include <linux/limits.h>
 #include <sys/stat.h>
@@ -1014,63 +1015,69 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
 
 static int bpf_map_find_btf_info(struct bpf_map *map, const struct btf *btf)
 {
+	const struct btf_type *container_type;
+	const struct btf_member *key, *value;
+	__s32 key_id, value_id, container_id;
 	struct bpf_map_def *def = &map->def;
 	const size_t max_name = 256;
+	char container_name[max_name];
 	__s64 key_size, value_size;
-	__s32 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",
+	if (snprintf(container_name, max_name, "____btf_map_%s", map->name) ==
+	    max_name) {
+		pr_warning("map:%s length of '____btf_map_%s' 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;
+	container_id = btf__find_by_name(btf, container_name);
+	if (container_id < 0) {
+		pr_debug("map:%s container_name:%s cannot be found in BTF. Missing BPF_ANNOTATE_KV_PAIR?\n",
+			 map->name, container_name);
+		return container_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;
+	container_type = btf__type_by_id(btf, container_id);
+	if (IS_ERR(container_type)) {
+		pr_warning("map:%s cannot find BTF type for container_id:%u\n",
+			   map->name, container_id);
+		return PTR_ERR(container_type);
 	}
 
-	if (def->key_size != key_size) {
-		pr_warning("map:%s key_type:%s has BTF type_size:%u != key_size:%u\n",
-			   map->name, name, (unsigned int)key_size, def->key_size);
+	if (BTF_INFO_KIND(container_type->info) != BTF_KIND_STRUCT &&
+	    BTF_INFO_VLEN(container_type->info) < 2) {
+		pr_warning("map:%s container_name:%s is an invalid container struct\n",
+			   map->name, container_name);
 		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;
+	key = (struct btf_member *)(container_type + 1);
+	value = key + 1;
+	key_id = key->type;
+	value_id = value->type;
+
+	key_size = btf__resolve_size(btf, key_id);
+	if (key_size < 0) {
+		pr_warning("map:%s invalid BTF key_type_size\n",
+			   map->name);
+		return key_size;
 	}
 
-	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;
+	if (def->key_size != key_size) {
+		pr_warning("map:%s btf_key_type_size:%u != map_def_key_size:%u\n",
+			   map->name, (__u32)key_size, def->key_size);
+		return -EINVAL;
 	}
 
 	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);
+		pr_warning("map:%s invalid BTF value_type_size\n", map->name);
 		return value_size;
 	}
 
 	if (def->value_size != value_size) {
-		pr_warning("map:%s value_type:%s has BTF type_size:%u != value_size:%u\n",
-			   map->name, name, (unsigned int)value_size, def->value_size);
+		pr_warning("map:%s btf_value_type_size:%u != map_def_value_size:%u\n",
+			   map->name, (__u32)value_size, def->value_size);
 		return -EINVAL;
 	}
 
diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index f2f28b6c8915..0ce47b46df70 100644
--- a/tools/testing/selftests/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h
@@ -158,6 +158,15 @@ struct bpf_map_def {
 	unsigned int numa_node;
 };
 
+#define BPF_ANNOTATE_KV_PAIR(name, type_key, type_val)		\
+	struct ____btf_map_##name {				\
+		type_key key;                                   \
+		type_val value;                                 \
+	};							\
+	struct ____btf_map_##name                               \
+	__attribute__ ((section(".maps." #name), used))		\
+		____btf_map_##name = { }
+
 static int (*bpf_skb_load_bytes)(void *ctx, int off, void *to, int len) =
 	(void *) BPF_FUNC_skb_load_bytes;
 static int (*bpf_skb_store_bytes)(void *ctx, int off, void *from, int len, int flags) =
diff --git a/tools/testing/selftests/bpf/test_btf_haskv.c b/tools/testing/selftests/bpf/test_btf_haskv.c
index 8c7ca096ecf2..b21b876f475d 100644
--- a/tools/testing/selftests/bpf/test_btf_haskv.c
+++ b/tools/testing/selftests/bpf/test_btf_haskv.c
@@ -10,11 +10,6 @@ struct ipv_counts {
 	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),
@@ -22,6 +17,8 @@ struct bpf_map_def SEC("maps") btf_map = {
 	.max_entries = 4,
 };
 
+BPF_ANNOTATE_KV_PAIR(btf_map, int, struct ipv_counts);
+
 struct dummy_tracepoint_args {
 	unsigned long long pad;
 	struct sock *sock;
-- 
2.17.1

Re: [PATCH bpf 3/3] bpf: Introduce BPF_ANNOTATE_KV_PAIR

[Martin KaFai Lau]

On Fri, Jul 20, 2018 at 06:39:33PM -0700, Martin KaFai Lau wrote:
> This patch introduces BPF_ANNOTATE_KV_PAIR to signal the
> bpf loader about the btf key_type and value_type of a bpf map.
> Please refer to the changes in test_btf_haskv.c for its usage.
> Both iproute2 and libbpf loader will then have the same
> convention to find out the map's btf_key_type_id and
> btf_value_type_id from a map's name.
> 
> Fixes: 8a138aed4a80 ("bpf: btf: Add BTF support to libbpf")
> Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
> Signed-off-by: Martin KaFai Lau <kafai@fb.com>
> ---
>  tools/lib/bpf/btf.c                          |  8 +++
>  tools/lib/bpf/btf.h                          |  1 +
>  tools/lib/bpf/libbpf.c                       | 71 +++++++++++---------
>  tools/testing/selftests/bpf/bpf_helpers.h    |  9 +++
>  tools/testing/selftests/bpf/test_btf_haskv.c |  7 +-
>  5 files changed, 59 insertions(+), 37 deletions(-)
> 
> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> index ce77b5b57912..748f0b11361d 100644
> --- a/tools/lib/bpf/btf.c
> +++ b/tools/lib/bpf/btf.c
> @@ -288,6 +288,14 @@ __s32 btf__find_by_name(const struct btf *btf, const char *type_name)
>  	return -ENOENT;
>  }
>  
> +const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 id)
> +{
> +	if (!id || id > btf->nr_types)
> +		return ERR_PTR(-EINVAL);
> +
> +	return btf->types[id];
> +}
> +
>  void btf__free(struct btf *btf)
>  {
>  	if (!btf)
> diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
> index ed3a84370ccc..38ebf66613e4 100644
> --- a/tools/lib/bpf/btf.h
> +++ b/tools/lib/bpf/btf.h
> @@ -16,6 +16,7 @@ typedef int (*btf_print_fn_t)(const char *, ...)
>  void btf__free(struct btf *btf);
>  struct btf *btf__new(__u8 *data, __u32 size, btf_print_fn_t err_log);
>  __s32 btf__find_by_name(const struct btf *btf, const char *type_name);
> +const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 id);
>  __s64 btf__resolve_size(const struct btf *btf, __u32 type_id);
>  int btf__fd(const struct btf *btf);
>  
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 6deb4fe4fffe..5ff7755efa6b 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -36,6 +36,7 @@
>  #include <linux/err.h>
>  #include <linux/kernel.h>
>  #include <linux/bpf.h>
> +#include <linux/btf.h>
>  #include <linux/list.h>
>  #include <linux/limits.h>
>  #include <sys/stat.h>
> @@ -1014,63 +1015,69 @@ bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
>  
>  static int bpf_map_find_btf_info(struct bpf_map *map, const struct btf *btf)
>  {
> +	const struct btf_type *container_type;
> +	const struct btf_member *key, *value;
> +	__s32 key_id, value_id, container_id;
>  	struct bpf_map_def *def = &map->def;
>  	const size_t max_name = 256;
> +	char container_name[max_name];
>  	__s64 key_size, value_size;
> -	__s32 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",
> +	if (snprintf(container_name, max_name, "____btf_map_%s", map->name) ==
> +	    max_name) {
> +		pr_warning("map:%s length of '____btf_map_%s' 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;
> +	container_id = btf__find_by_name(btf, container_name);
> +	if (container_id < 0) {
> +		pr_debug("map:%s container_name:%s cannot be found in BTF. Missing BPF_ANNOTATE_KV_PAIR?\n",
> +			 map->name, container_name);
> +		return container_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;
> +	container_type = btf__type_by_id(btf, container_id);
> +	if (IS_ERR(container_type)) {
> +		pr_warning("map:%s cannot find BTF type for container_id:%u\n",
> +			   map->name, container_id);
> +		return PTR_ERR(container_type);
>  	}
>  
> -	if (def->key_size != key_size) {
> -		pr_warning("map:%s key_type:%s has BTF type_size:%u != key_size:%u\n",
> -			   map->name, name, (unsigned int)key_size, def->key_size);
> +	if (BTF_INFO_KIND(container_type->info) != BTF_KIND_STRUCT &&
> +	    BTF_INFO_VLEN(container_type->info) < 2) {
There is a mistake in this check.  I will spin v2.

> +		pr_warning("map:%s container_name:%s is an invalid container struct\n",
> +			   map->name, container_name);
>  		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;
> +	key = (struct btf_member *)(container_type + 1);
> +	value = key + 1;
> +	key_id = key->type;
> +	value_id = value->type;
> +
> +	key_size = btf__resolve_size(btf, key_id);
> +	if (key_size < 0) {
> +		pr_warning("map:%s invalid BTF key_type_size\n",
> +			   map->name);
> +		return key_size;
>  	}
>  
> -	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;
> +	if (def->key_size != key_size) {
> +		pr_warning("map:%s btf_key_type_size:%u != map_def_key_size:%u\n",
> +			   map->name, (__u32)key_size, def->key_size);
> +		return -EINVAL;
>  	}
>  
>  	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);
> +		pr_warning("map:%s invalid BTF value_type_size\n", map->name);
>  		return value_size;
>  	}
>  
>  	if (def->value_size != value_size) {
> -		pr_warning("map:%s value_type:%s has BTF type_size:%u != value_size:%u\n",
> -			   map->name, name, (unsigned int)value_size, def->value_size);
> +		pr_warning("map:%s btf_value_type_size:%u != map_def_value_size:%u\n",
> +			   map->name, (__u32)value_size, def->value_size);
>  		return -EINVAL;
>  	}
>  
> diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
> index f2f28b6c8915..0ce47b46df70 100644
> --- a/tools/testing/selftests/bpf/bpf_helpers.h
> +++ b/tools/testing/selftests/bpf/bpf_helpers.h
> @@ -158,6 +158,15 @@ struct bpf_map_def {
>  	unsigned int numa_node;
>  };
>  
> +#define BPF_ANNOTATE_KV_PAIR(name, type_key, type_val)		\
> +	struct ____btf_map_##name {				\
> +		type_key key;                                   \
> +		type_val value;                                 \
> +	};							\
> +	struct ____btf_map_##name                               \
> +	__attribute__ ((section(".maps." #name), used))		\
> +		____btf_map_##name = { }
> +
>  static int (*bpf_skb_load_bytes)(void *ctx, int off, void *to, int len) =
>  	(void *) BPF_FUNC_skb_load_bytes;
>  static int (*bpf_skb_store_bytes)(void *ctx, int off, void *from, int len, int flags) =
> diff --git a/tools/testing/selftests/bpf/test_btf_haskv.c b/tools/testing/selftests/bpf/test_btf_haskv.c
> index 8c7ca096ecf2..b21b876f475d 100644
> --- a/tools/testing/selftests/bpf/test_btf_haskv.c
> +++ b/tools/testing/selftests/bpf/test_btf_haskv.c
> @@ -10,11 +10,6 @@ struct ipv_counts {
>  	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),
> @@ -22,6 +17,8 @@ struct bpf_map_def SEC("maps") btf_map = {
>  	.max_entries = 4,
>  };
>  
> +BPF_ANNOTATE_KV_PAIR(btf_map, int, struct ipv_counts);
> +
>  struct dummy_tracepoint_args {
>  	unsigned long long pad;
>  	struct sock *sock;
> -- 
> 2.17.1
>