Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ef99b02b authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Daniel Borkmann
Browse files

libbpf: capture value in BTF type info for BTF-defined map defs 



Change BTF-defined map definitions to capture compile-time integer
values as part of BTF type definition, to avoid split of key/value type
information and actual type/size/flags initialization for maps.

Signed-off-by: default avatarAndrii Nakryiko <andriin@fb.com>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent c5f48c92

tools/lib/bpf/libbpf.c

+28 −30
Original line number Diff line number Diff line
@@ -1029,40 +1029,40 @@ static const struct btf_type *skip_mods_and_typedefs(const struct btf *btf, 
	}

}



static bool get_map_field_int(const char *map_name,

			      const struct btf *btf,

/*

 * Fetch integer attribute of BTF map definition. Such attributes are

 * represented using a pointer to an array, in which dimensionality of array

 * encodes specified integer value. E.g., int (*type)[BPF_MAP_TYPE_ARRAY];

 * encodes `type => BPF_MAP_TYPE_ARRAY` key/value pair completely using BTF

 * type definition, while using only sizeof(void *) space in ELF data section.

 */

static bool get_map_field_int(const char *map_name, const struct btf *btf,

			      const struct btf_type *def,

			      const struct btf_member *m,

			      const void *data, __u32 *res) {

			      const struct btf_member *m, __u32 *res) {

	const struct btf_type *t = skip_mods_and_typedefs(btf, m->type);

	const char *name = btf__name_by_offset(btf, m->name_off);

	__u32 int_info = *(const __u32 *)(const void *)(t + 1);

	const struct btf_array *arr_info;

	const struct btf_type *arr_t;



	if (BTF_INFO_KIND(t->info) != BTF_KIND_INT) {

		pr_warning("map '%s': attr '%s': expected INT, got %u.\n",

	if (BTF_INFO_KIND(t->info) != BTF_KIND_PTR) {

		pr_warning("map '%s': attr '%s': expected PTR, got %u.\n",

			   map_name, name, BTF_INFO_KIND(t->info));

		return false;

	}

	if (t->size != 4 || BTF_INT_BITS(int_info) != 32 ||

	    BTF_INT_OFFSET(int_info)) {

		pr_warning("map '%s': attr '%s': expected 32-bit non-bitfield integer, "

			   "got %u-byte (%d-bit) one with bit offset %d.\n",

			   map_name, name, t->size, BTF_INT_BITS(int_info),

			   BTF_INT_OFFSET(int_info));

		return false;

	}

	if (BTF_INFO_KFLAG(def->info) && BTF_MEMBER_BITFIELD_SIZE(m->offset)) {

		pr_warning("map '%s': attr '%s': bitfield is not supported.\n",

			   map_name, name);



	arr_t = btf__type_by_id(btf, t->type);

	if (!arr_t) {

		pr_warning("map '%s': attr '%s': type [%u] not found.\n",

			   map_name, name, t->type);

		return false;

	}

	if (m->offset % 32) {

		pr_warning("map '%s': attr '%s': unaligned fields are not supported.\n",

			   map_name, name);

	if (BTF_INFO_KIND(arr_t->info) != BTF_KIND_ARRAY) {

		pr_warning("map '%s': attr '%s': expected ARRAY, got %u.\n",

			   map_name, name, BTF_INFO_KIND(arr_t->info));

		return false;

	}



	*res = *(const __u32 *)(data + m->offset / 8);

	arr_info = (const void *)(arr_t + 1);

	*res = arr_info->nelems;

	return true;

}
@@ -1075,7 +1075,6 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj, 
	const struct btf_var_secinfo *vi;

	const struct btf_var *var_extra;

	const struct btf_member *m;

	const void *def_data;

	const char *map_name;

	struct bpf_map *map;

	int vlen, i;
@@ -1132,7 +1131,6 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj, 
	pr_debug("map '%s': at sec_idx %d, offset %zu.\n",

		 map_name, map->sec_idx, map->sec_offset);



	def_data = data->d_buf + vi->offset;

	vlen = BTF_INFO_VLEN(def->info);

	m = (const void *)(def + 1);

	for (i = 0; i < vlen; i++, m++) {
@@ -1145,19 +1143,19 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj, 
		}

		if (strcmp(name, "type") == 0) {

			if (!get_map_field_int(map_name, obj->btf, def, m,

					       def_data, &map->def.type))

					       &map->def.type))

				return -EINVAL;

			pr_debug("map '%s': found type = %u.\n",

				 map_name, map->def.type);

		} else if (strcmp(name, "max_entries") == 0) {

			if (!get_map_field_int(map_name, obj->btf, def, m,

					       def_data, &map->def.max_entries))

					       &map->def.max_entries))

				return -EINVAL;

			pr_debug("map '%s': found max_entries = %u.\n",

				 map_name, map->def.max_entries);

		} else if (strcmp(name, "map_flags") == 0) {

			if (!get_map_field_int(map_name, obj->btf, def, m,

					       def_data, &map->def.map_flags))

					       &map->def.map_flags))

				return -EINVAL;

			pr_debug("map '%s': found map_flags = %u.\n",

				 map_name, map->def.map_flags);
@@ -1165,7 +1163,7 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj, 
			__u32 sz;



			if (!get_map_field_int(map_name, obj->btf, def, m,

					       def_data, &sz))

					       &sz))

				return -EINVAL;

			pr_debug("map '%s': found key_size = %u.\n",

				 map_name, sz);
@@ -1208,7 +1206,7 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj, 
			__u32 sz;



			if (!get_map_field_int(map_name, obj->btf, def, m,

					       def_data, &sz))

					       &sz))

				return -EINVAL;

			pr_debug("map '%s': found value_size = %u.\n",

				 map_name, sz);