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bpf: adding support for map in map in libbpf

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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: Nikita V. Shirokov <tehnerd@tehnerd.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Nikita V. Shirokov 2018-11-20 20:55:56 -08:00 committed by Daniel Borkmann
parent 5b32a23e1d
commit addb9fc90f
2 changed files with 36 additions and 6 deletions
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40
tools/lib/bpf/libbpf.c
View File

@ -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;
/*
* 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++)
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)).
*/
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)
{

2
tools/lib/bpf/libbpf.h
View File

@ -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 {