Commit 38d5d3b3 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Daniel Borkmann
Browse files

bpf: Introduce BPF_ANNOTATE_KV_PAIR 



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: 8a138aed ("bpf: btf: Add BTF support to libbpf")
Suggested-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 5b891af7

tools/lib/bpf/btf.c

+3 −4
Original line number Diff line number Diff line
@@ -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)

tools/lib/bpf/btf.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

tools/lib/bpf/libbpf.c

+40 −35
Original line number Diff line number Diff line
@@ -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;

}

tools/testing/selftests/bpf/bpf_helpers.h

+9 −0
Original line number Diff line number Diff line
@@ -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) =

tools/testing/selftests/bpf/test_btf_haskv.c

+2 −5
Original line number Diff line number Diff line
@@ -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;

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