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: Nikita V. Shirokov <tehnerd@tehnerd.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index edbae2b..0f14f7c 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -175,6 +175,7 @@
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 @@
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 @@
}
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 @@
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 @@
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)
{
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 74e57e0..f30c3d0 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -297,6 +297,8 @@
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 {
