[PATCH bpf-next v4 2/5] libbpf: Add "map_extra" as a per-map-type extra flag

[Joanne Koong <joannekoong@fb.com>]

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 bitset map, the lower 4 bits of map_extra
is used to denote the number of hash functions.

Signed-off-by: Joanne Koong <joannekoong@fb.com>
---
 include/uapi/linux/bpf.h        |  1 +
 tools/include/uapi/linux/bpf.h  |  1 +
 tools/lib/bpf/bpf.c             |  1 +
 tools/lib/bpf/bpf.h             |  1 +
 tools/lib/bpf/bpf_helpers.h     |  1 +
 tools/lib/bpf/libbpf.c          | 25 ++++++++++++++++++++++++-
 tools/lib/bpf/libbpf.h          |  4 ++++
 tools/lib/bpf/libbpf.map        |  2 ++
 tools/lib/bpf/libbpf_internal.h |  4 +++-
 9 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index b40fa1a72a75..a6f225e9c95a 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5639,6 +5639,7 @@ struct bpf_map_info {
 	__u32 btf_id;
 	__u32 btf_key_type_id;
 	__u32 btf_value_type_id;
+	__u32 map_extra;
 } __attribute__((aligned(8)));
 
 struct bpf_btf_info {
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index b40fa1a72a75..a6f225e9c95a 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5639,6 +5639,7 @@ struct bpf_map_info {
 	__u32 btf_id;
 	__u32 btf_key_type_id;
 	__u32 btf_value_type_id;
+	__u32 map_extra;
 } __attribute__((aligned(8)));
 
 struct bpf_btf_info {
diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 7d1741ceaa32..41e3e85e7789 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -97,6 +97,7 @@ int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr)
 	attr.btf_key_type_id = create_attr->btf_key_type_id;
 	attr.btf_value_type_id = create_attr->btf_value_type_id;
 	attr.map_ifindex = create_attr->map_ifindex;
+	attr.map_extra = create_attr->map_extra;
 	if (attr.map_type == BPF_MAP_TYPE_STRUCT_OPS)
 		attr.btf_vmlinux_value_type_id =
 			create_attr->btf_vmlinux_value_type_id;
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 6fffb3cdf39b..c4049f2d63cc 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -50,6 +50,7 @@ struct bpf_create_map_attr {
 		__u32 inner_map_fd;
 		__u32 btf_vmlinux_value_type_id;
 	};
+	__u32 map_extra;
 };
 
 LIBBPF_API int
diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index 963b1060d944..bce5a0090f3f 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -133,6 +133,7 @@ struct bpf_map_def {
 	unsigned int value_size;
 	unsigned int max_entries;
 	unsigned int map_flags;
+	unsigned int map_extra;
 };
 
 enum libbpf_pin_type {
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ed313fd491bd..12a9ecd45a78 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2274,6 +2274,10 @@ 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) {
+			if (!get_map_field_int(map_name, btf, m, &map_def->map_extra))
+				return -EINVAL;
+			map_def->parts |= MAP_DEF_MAP_EXTRA;
 		} else {
 			if (strict) {
 				pr_warn("map '%s': unknown field '%s'.\n", map_name, name);
@@ -2298,6 +2302,7 @@ 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->def.map_extra = def->map_extra;
 
 	map->numa_node = def->numa_node;
 	map->btf_key_type_id = def->key_type_id;
@@ -2322,6 +2327,8 @@ static void fill_map_from_def(struct bpf_map *map, const struct btf_map_def *def
 		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);
+	if (def->parts & MAP_DEF_MAP_EXTRA)
+		pr_debug("map '%s': found map_extra = %u.\n", map->name, 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)
@@ -4017,6 +4024,7 @@ int bpf_map__reuse_fd(struct bpf_map *map, int fd)
 	map->def.value_size = info.value_size;
 	map->def.max_entries = info.max_entries;
 	map->def.map_flags = info.map_flags;
+	map->def.map_extra = info.map_extra;
 	map->btf_key_type_id = info.btf_key_type_id;
 	map->btf_value_type_id = info.btf_value_type_id;
 	map->reused = true;
@@ -4534,7 +4542,8 @@ 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->def.map_extra);
 }
 
 static int
@@ -4631,6 +4640,7 @@ 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 = def->map_extra;
 
 	if (def->type == BPF_MAP_TYPE_PERF_EVENT_ARRAY && !def->max_entries) {
 		int nr_cpus;
@@ -8637,6 +8647,19 @@ int bpf_map__set_map_flags(struct bpf_map *map, __u32 flags)
 	return 0;
 }
 
+__u32 bpf_map__map_extra(const struct bpf_map *map)
+{
+	return map->def.map_extra;
+}
+
+int bpf_map__set_map_extra(struct bpf_map *map, __u32 map_extra)
+{
+	if (map->fd >= 0)
+		return libbpf_err(-EBUSY);
+	map->def.map_extra = map_extra;
+	return 0;
+}
+
 __u32 bpf_map__numa_node(const struct bpf_map *map)
 {
 	return map->numa_node;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 89ca9c83ed4e..55e8dfe6f3e1 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -486,6 +486,7 @@ struct bpf_map_def {
 	unsigned int value_size;
 	unsigned int max_entries;
 	unsigned int map_flags;
+	unsigned int map_extra;
 };
 
 /**
@@ -562,6 +563,9 @@ LIBBPF_API __u32 bpf_map__btf_value_type_id(const struct bpf_map *map);
 /* get/set map if_index */
 LIBBPF_API __u32 bpf_map__ifindex(const struct bpf_map *map);
 LIBBPF_API int bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex);
+/* get/set map map_extra flags */
+LIBBPF_API __u32 bpf_map__map_extra(const struct bpf_map *map);
+LIBBPF_API int bpf_map__set_map_extra(struct bpf_map *map, __u32 map_extra);
 
 typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *);
 LIBBPF_API int bpf_map__set_priv(struct bpf_map *map, void *priv,
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index f270d25e4af3..308378b3f20b 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -395,4 +395,6 @@ LIBBPF_0.6.0 {
 		bpf_object__prev_program;
 		btf__add_btf;
 		btf__add_tag;
+		bpf_map__map_extra;
+		bpf_map__set_map_extra;
 } LIBBPF_0.5.0;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index f7fd3944d46d..188db854d9c2 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -193,8 +193,9 @@ enum map_def_parts {
 	MAP_DEF_NUMA_NODE	= 0x080,
 	MAP_DEF_PINNING		= 0x100,
 	MAP_DEF_INNER_MAP	= 0x200,
+	MAP_DEF_MAP_EXTRA	= 0x400,
 
-	MAP_DEF_ALL		= 0x3ff, /* combination of all above */
+	MAP_DEF_ALL		= 0x7ff, /* combination of all above */
 };
 
 struct btf_map_def {
@@ -208,6 +209,7 @@ struct btf_map_def {
 	__u32 map_flags;
 	__u32 numa_node;
 	__u32 pinning;
+	__u32 map_extra;
 };
 
 int parse_btf_map_def(const char *map_name, struct btf *btf,
-- 
2.30.2