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 <dan...@iogearbox.net>
Signed-off-by: Martin KaFai Lau <ka...@fb.com>
---
tools/lib/bpf/btf.c | 7 +-
tools/lib/bpf/btf.h | 2 +
tools/lib/bpf/libbpf.c | 75 +++++++++++---------
tools/testing/selftests/bpf/bpf_helpers.h | 9 +++
tools/testing/selftests/bpf/test_btf_haskv.c | 7 +-
5 files changed, 56 insertions(+), 44 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index b80de80b4584..2d270c560df3 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -189,8 +189,7 @@ static int btf_parse_type_sec(struct btf *btf,
btf_print_fn_t err_log)
return 0;
}
-static const struct btf_type *btf_type_by_id(const struct btf *btf,
- __u32 type_id)
+const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
{
if (type_id > btf->nr_types)
return NULL;
@@ -233,7 +232,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32
type_id)
__s64 size = -1;
int i;
- t = btf_type_by_id(btf, type_id);
+ 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);
@@ -258,7 +257,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32
type_id)
return -EINVAL;
}
- t = btf_type_by_id(btf, type_id);
+ t = btf__type_by_id(btf, type_id);
}
if (size < 0)
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index ed3a84370ccc..e2a09a155f84 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -9,6 +9,7 @@
#define BTF_ELF_SEC ".BTF"
struct btf;
+struct btf_type;
typedef int (*btf_print_fn_t)(const char *, ...)
__attribute__((format(printf, 1, 2)));
@@ -16,6 +17,7 @@ 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..d881d370616c 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>
@@ -1014,68 +1015,72 @@ 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;
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];
+ __s32 container_id;
- /* 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 (!container_type) {
+ pr_warning("map:%s cannot find BTF type for container_id:%u\n",
+ map->name, container_id);
+ return -EINVAL;
}
- 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_size = btf__resolve_size(btf, key->type);
+ 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);
+ value_size = btf__resolve_size(btf, value->type);
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;
}
- map->btf_key_type_id = key_id;
- map->btf_value_type_id = value_id;
+ map->btf_key_type_id = key->type;
+ map->btf_value_type_id = value->type;
return 0;
}
diff --git a/tools/testing/selftests/bpf/bpf_helpers.h
b/tools/testing/selftests/bpf/bpf_helpers.h
index f2f28b6c8915..810de20e8e26 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
