libbpf: Add "map_extra" as a per-map-type extra flag

This patch adds the libbpf infrastructure for supporting a
per-map-type "map_extra" field, whose definition will be
idiosyncratic depending on map type.

For example, for the bloom filter map, the lower 4 bits of
map_extra is used to denote the number of hash functions.

Please note that until libbpf 1.0 is here, the
"bpf_create_map_params" struct is used as a temporary
means for propagating the map_extra field to the kernel.

Signed-off-by: Joanne Koong <joannekoong@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211027234504.30744-3-joannekoong@fb.com

1 files changed, 33 insertions, 5 deletions

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 59d39ce9f375..232e4efe82e9 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -400,6 +400,7 @@ struct bpf_map {
 	char *pin_path;
 	bool pinned;
 	bool reused;
+	__u64 map_extra;
 };
 
 enum extern_type {
@@ -2324,6 +2325,13 @@ int parse_btf_map_def(const char *map_name, struct btf *btf,
 			}
 			map_def->pinning = val;
 			map_def->parts |= MAP_DEF_PINNING;
+		} else if (strcmp(name, "map_extra") == 0) {
+			__u32 map_extra;
+
+			if (!get_map_field_int(map_name, btf, m, &map_extra))
+				return -EINVAL;
+			map_def->map_extra = map_extra;
+			map_def->parts |= MAP_DEF_MAP_EXTRA;
 		} else {
 			if (strict) {
 				pr_warn("map '%s': unknown field '%s'.\n", map_name, name);
@@ -2348,6 +2356,7 @@ static void fill_map_from_def(struct bpf_map *map, const struct btf_map_def *def
 	map->def.value_size = def->value_size;
 	map->def.max_entries = def->max_entries;
 	map->def.map_flags = def->map_flags;
+	map->map_extra = def->map_extra;
 
 	map->numa_node = def->numa_node;
 	map->btf_key_type_id = def->key_type_id;
@@ -2371,7 +2380,10 @@ static void fill_map_from_def(struct bpf_map *map, const struct btf_map_def *def
 	if (def->parts & MAP_DEF_MAX_ENTRIES)
 		pr_debug("map '%s': found max_entries = %u.\n", map->name, def->max_entries);
 	if (def->parts & MAP_DEF_MAP_FLAGS)
-		pr_debug("map '%s': found map_flags = %u.\n", map->name, def->map_flags);
+		pr_debug("map '%s': found map_flags = 0x%x.\n", map->name, def->map_flags);
+	if (def->parts & MAP_DEF_MAP_EXTRA)
+		pr_debug("map '%s': found map_extra = 0x%llx.\n", map->name,
+			 (unsigned long long)def->map_extra);
 	if (def->parts & MAP_DEF_PINNING)
 		pr_debug("map '%s': found pinning = %u.\n", map->name, def->pinning);
 	if (def->parts & MAP_DEF_NUMA_NODE)
@@ -4210,6 +4222,7 @@ int bpf_map__reuse_fd(struct bpf_map *map, int fd)
 	map->btf_key_type_id = info.btf_key_type_id;
 	map->btf_value_type_id = info.btf_value_type_id;
 	map->reused = true;
+	map->map_extra = info.map_extra;
 
 	return 0;
 
@@ -4724,7 +4737,8 @@ static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd)
 		map_info.key_size == map->def.key_size &&
 		map_info.value_size == map->def.value_size &&
 		map_info.max_entries == map->def.max_entries &&
-		map_info.map_flags == map->def.map_flags);
+		map_info.map_flags == map->def.map_flags &&
+		map_info.map_extra == map->map_extra);
 }
 
 static int
@@ -4807,7 +4821,7 @@ static void bpf_map__destroy(struct bpf_map *map);
 
 static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, bool is_inner)
 {
-	struct bpf_create_map_attr create_attr;
+	struct bpf_create_map_params create_attr;
 	struct bpf_map_def *def = &map->def;
 	int err = 0;
 
@@ -4821,6 +4835,7 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b
 	create_attr.key_size = def->key_size;
 	create_attr.value_size = def->value_size;
 	create_attr.numa_node = map->numa_node;
+	create_attr.map_extra = map->map_extra;
 
 	if (def->type == BPF_MAP_TYPE_PERF_EVENT_ARRAY && !def->max_entries) {
 		int nr_cpus;
@@ -4895,7 +4910,7 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b
 		 */
 		map->fd = 0;
 	} else {
-		map->fd = bpf_create_map_xattr(&create_attr);
+		map->fd = libbpf__bpf_create_map_xattr(&create_attr);
 	}
 	if (map->fd < 0 && (create_attr.btf_key_type_id ||
 			    create_attr.btf_value_type_id)) {
@@ -4910,7 +4925,7 @@ static int bpf_object__create_map(struct bpf_object *obj, struct bpf_map *map, b
 		create_attr.btf_value_type_id = 0;
 		map->btf_key_type_id = 0;
 		map->btf_value_type_id = 0;
-		map->fd = bpf_create_map_xattr(&create_attr);
+		map->fd = libbpf__bpf_create_map_xattr(&create_attr);
 	}
 
 	err = map->fd < 0 ? -errno : 0;
@@ -8880,6 +8895,19 @@ int bpf_map__set_map_flags(struct bpf_map *map, __u32 flags)
 	return 0;
 }
 
+__u64 bpf_map__map_extra(const struct bpf_map *map)
+{
+	return map->map_extra;
+}
+
+int bpf_map__set_map_extra(struct bpf_map *map, __u64 map_extra)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->map_extra = map_extra;
+	return 0;
+}
+
 __u32 bpf_map__numa_node(const struct bpf_map *map)
 {
 	return map->numa_node;