Commit addb9fc9 authored by Nikita V. Shirokov's avatar Nikita V. Shirokov Committed by Daniel Borkmann
Browse files

bpf: adding support for map in map in libbpf 



idea is pretty simple. for specified map (pointed by struct bpf_map)
we would provide descriptor of already loaded map, which is going to be
used as a prototype for inner map. proposed workflow:
1) open bpf's object (bpf_object__open)
2) create bpf's map which is going to be used as a prototype
3) find (by name) map-in-map which you want to load and update w/
descriptor of inner map w/ a new helper from this patch
4) load bpf program w/ bpf_object__load

Signed-off-by: default avatarNikita V. Shirokov <tehnerd@tehnerd.com>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 5b32a23e

tools/lib/bpf/libbpf.c

+34 −6
Original line number Diff line number Diff line
@@ -175,6 +175,7 @@ struct bpf_map { 
	char *name;

	size_t offset;

	int map_ifindex;

	int inner_map_fd;

	struct bpf_map_def def;

	__u32 btf_key_type_id;

	__u32 btf_value_type_id;
@@ -605,6 +606,14 @@ static int compare_bpf_map(const void *_a, const void *_b) 
	return a->offset - b->offset;

}



static bool bpf_map_type__is_map_in_map(enum bpf_map_type type)

{

	if (type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||

	    type == BPF_MAP_TYPE_HASH_OF_MAPS)

		return true;

	return false;

}



static int

bpf_object__init_maps(struct bpf_object *obj, int flags)

{
@@ -668,13 +677,15 @@ bpf_object__init_maps(struct bpf_object *obj, int flags) 
	}

	obj->nr_maps = nr_maps;



	for (i = 0; i < nr_maps; i++) {

		/*

		 * fill all fd with -1 so won't close incorrect

		 * fd (fd=0 is stdin) when failure (zclose won't close

		 * negative fd)).

		 */

	for (i = 0; i < nr_maps; i++)

		obj->maps[i].fd = -1;

		obj->maps[i].inner_map_fd = -1;

	}



	/*

	 * Fill obj->maps using data in "maps" section.
@@ -1222,6 +1233,9 @@ bpf_object__create_maps(struct bpf_object *obj) 
		create_attr.btf_fd = 0;

		create_attr.btf_key_type_id = 0;

		create_attr.btf_value_type_id = 0;

		if (bpf_map_type__is_map_in_map(def->type) &&

		    map->inner_map_fd >= 0)

			create_attr.inner_map_fd = map->inner_map_fd;



		if (obj->btf && !bpf_map_find_btf_info(map, obj->btf)) {

			create_attr.btf_fd = btf__fd(obj->btf);
@@ -2681,6 +2695,20 @@ void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex) 
	map->map_ifindex = ifindex;

}



int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd)

{

	if (!bpf_map_type__is_map_in_map(map->def.type)) {

		pr_warning("error: unsupported map type\n");

		return -EINVAL;

	}

	if (map->inner_map_fd != -1) {

		pr_warning("error: inner_map_fd already specified\n");

		return -EINVAL;

	}

	map->inner_map_fd = fd;

	return 0;

}



static struct bpf_map *

__bpf_map__iter(struct bpf_map *m, struct bpf_object *obj, int i)

{

tools/lib/bpf/libbpf.h

+2 −0
Original line number Diff line number Diff line
@@ -297,6 +297,8 @@ LIBBPF_API void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex); 
LIBBPF_API int bpf_map__pin(struct bpf_map *map, const char *path);

LIBBPF_API int bpf_map__unpin(struct bpf_map *map, const char *path);



LIBBPF_API int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd);



LIBBPF_API long libbpf_get_error(const void *ptr);



struct bpf_prog_load_attr {

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