libbpf: Refactor BTF-defined map definition parsing logic

Factor out BTF map definition logic into stand-alone routine for easier reuse
for map-in-map case.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200429002739.48006-2-andriin@fb.com

1 files changed, 103 insertions, 92 deletions

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 8e1dc6980fac..7d10436d7b58 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1914,109 +1914,54 @@ static int build_map_pin_path(struct bpf_map *map, const char *path)
 	return 0;
 }
 
-static int bpf_object__init_user_btf_map(struct bpf_object *obj,
-					 const struct btf_type *sec,
-					 int var_idx, int sec_idx,
-					 const Elf_Data *data, bool strict,
-					 const char *pin_root_path)
+
+static int parse_btf_map_def(struct bpf_object *obj,
+			     struct bpf_map *map,
+			     const struct btf_type *def,
+			     bool strict,
+			     const char *pin_root_path)
 {
-	const struct btf_type *var, *def, *t;
-	const struct btf_var_secinfo *vi;
-	const struct btf_var *var_extra;
+	const struct btf_type *t;
 	const struct btf_member *m;
-	const char *map_name;
-	struct bpf_map *map;
 	int vlen, i;
 
-	vi = btf_var_secinfos(sec) + var_idx;
-	var = btf__type_by_id(obj->btf, vi->type);
-	var_extra = btf_var(var);
-	map_name = btf__name_by_offset(obj->btf, var->name_off);
-	vlen = btf_vlen(var);
-
-	if (map_name == NULL || map_name[0] == '\0') {
-		pr_warn("map #%d: empty name.\n", var_idx);
-		return -EINVAL;
-	}
-	if ((__u64)vi->offset + vi->size > data->d_size) {
-		pr_warn("map '%s' BTF data is corrupted.\n", map_name);
-		return -EINVAL;
-	}
-	if (!btf_is_var(var)) {
-		pr_warn("map '%s': unexpected var kind %u.\n",
-			map_name, btf_kind(var));
-		return -EINVAL;
-	}
-	if (var_extra->linkage != BTF_VAR_GLOBAL_ALLOCATED &&
-	    var_extra->linkage != BTF_VAR_STATIC) {
-		pr_warn("map '%s': unsupported var linkage %u.\n",
-			map_name, var_extra->linkage);
-		return -EOPNOTSUPP;
-	}
-
-	def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
-	if (!btf_is_struct(def)) {
-		pr_warn("map '%s': unexpected def kind %u.\n",
-			map_name, btf_kind(var));
-		return -EINVAL;
-	}
-	if (def->size > vi->size) {
-		pr_warn("map '%s': invalid def size.\n", map_name);
-		return -EINVAL;
-	}
-
-	map = bpf_object__add_map(obj);
-	if (IS_ERR(map))
-		return PTR_ERR(map);
-	map->name = strdup(map_name);
-	if (!map->name) {
-		pr_warn("map '%s': failed to alloc map name.\n", map_name);
-		return -ENOMEM;
-	}
-	map->libbpf_type = LIBBPF_MAP_UNSPEC;
-	map->def.type = BPF_MAP_TYPE_UNSPEC;
-	map->sec_idx = sec_idx;
-	map->sec_offset = vi->offset;
-	pr_debug("map '%s': at sec_idx %d, offset %zu.\n",
-		 map_name, map->sec_idx, map->sec_offset);
-
 	vlen = btf_vlen(def);
 	m = btf_members(def);
 	for (i = 0; i < vlen; i++, m++) {
 		const char *name = btf__name_by_offset(obj->btf, m->name_off);
 
 		if (!name) {
-			pr_warn("map '%s': invalid field #%d.\n", map_name, i);
+			pr_warn("map '%s': invalid field #%d.\n", map->name, i);
 			return -EINVAL;
 		}
 		if (strcmp(name, "type") == 0) {
-			if (!get_map_field_int(map_name, obj->btf, m,
+			if (!get_map_field_int(map->name, obj->btf, m,
 					       &map->def.type))
 				return -EINVAL;
 			pr_debug("map '%s': found type = %u.\n",
-				 map_name, map->def.type);
+				 map->name, map->def.type);
 		} else if (strcmp(name, "max_entries") == 0) {
-			if (!get_map_field_int(map_name, obj->btf, m,
+			if (!get_map_field_int(map->name, obj->btf, m,
 					       &map->def.max_entries))
 				return -EINVAL;
 			pr_debug("map '%s': found max_entries = %u.\n",
-				 map_name, map->def.max_entries);
+				 map->name, map->def.max_entries);
 		} else if (strcmp(name, "map_flags") == 0) {
-			if (!get_map_field_int(map_name, obj->btf, m,
+			if (!get_map_field_int(map->name, obj->btf, m,
 					       &map->def.map_flags))
 				return -EINVAL;
 			pr_debug("map '%s': found map_flags = %u.\n",
-				 map_name, map->def.map_flags);
+				 map->name, map->def.map_flags);
 		} else if (strcmp(name, "key_size") == 0) {
 			__u32 sz;
 
-			if (!get_map_field_int(map_name, obj->btf, m, &sz))
+			if (!get_map_field_int(map->name, obj->btf, m, &sz))
 				return -EINVAL;
 			pr_debug("map '%s': found key_size = %u.\n",
-				 map_name, sz);
+				 map->name, sz);
 			if (map->def.key_size && map->def.key_size != sz) {
 				pr_warn("map '%s': conflicting key size %u != %u.\n",
-					map_name, map->def.key_size, sz);
+					map->name, map->def.key_size, sz);
 				return -EINVAL;
 			}
 			map->def.key_size = sz;
@@ -2026,25 +1971,25 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
 			t = btf__type_by_id(obj->btf, m->type);
 			if (!t) {
 				pr_warn("map '%s': key type [%d] not found.\n",
-					map_name, m->type);
+					map->name, m->type);
 				return -EINVAL;
 			}
 			if (!btf_is_ptr(t)) {
 				pr_warn("map '%s': key spec is not PTR: %u.\n",
-					map_name, btf_kind(t));
+					map->name, btf_kind(t));
 				return -EINVAL;
 			}
 			sz = btf__resolve_size(obj->btf, t->type);
 			if (sz < 0) {
 				pr_warn("map '%s': can't determine key size for type [%u]: %zd.\n",
-					map_name, t->type, (ssize_t)sz);
+					map->name, t->type, (ssize_t)sz);
 				return sz;
 			}
 			pr_debug("map '%s': found key [%u], sz = %zd.\n",
-				 map_name, t->type, (ssize_t)sz);
+				 map->name, t->type, (ssize_t)sz);
 			if (map->def.key_size && map->def.key_size != sz) {
 				pr_warn("map '%s': conflicting key size %u != %zd.\n",
-					map_name, map->def.key_size, (ssize_t)sz);
+					map->name, map->def.key_size, (ssize_t)sz);
 				return -EINVAL;
 			}
 			map->def.key_size = sz;
@@ -2052,13 +1997,13 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
 		} else if (strcmp(name, "value_size") == 0) {
 			__u32 sz;
 
-			if (!get_map_field_int(map_name, obj->btf, m, &sz))
+			if (!get_map_field_int(map->name, obj->btf, m, &sz))
 				return -EINVAL;
 			pr_debug("map '%s': found value_size = %u.\n",
-				 map_name, sz);
+				 map->name, sz);
 			if (map->def.value_size && map->def.value_size != sz) {
 				pr_warn("map '%s': conflicting value size %u != %u.\n",
-					map_name, map->def.value_size, sz);
+					map->name, map->def.value_size, sz);
 				return -EINVAL;
 			}
 			map->def.value_size = sz;
@@ -2068,25 +2013,25 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
 			t = btf__type_by_id(obj->btf, m->type);
 			if (!t) {
 				pr_warn("map '%s': value type [%d] not found.\n",
-					map_name, m->type);
+					map->name, m->type);
 				return -EINVAL;
 			}
 			if (!btf_is_ptr(t)) {
 				pr_warn("map '%s': value spec is not PTR: %u.\n",
-					map_name, btf_kind(t));
+					map->name, btf_kind(t));
 				return -EINVAL;
 			}
 			sz = btf__resolve_size(obj->btf, t->type);
 			if (sz < 0) {
 				pr_warn("map '%s': can't determine value size for type [%u]: %zd.\n",
-					map_name, t->type, (ssize_t)sz);
+					map->name, t->type, (ssize_t)sz);
 				return sz;
 			}
 			pr_debug("map '%s': found value [%u], sz = %zd.\n",
-				 map_name, t->type, (ssize_t)sz);
+				 map->name, t->type, (ssize_t)sz);
 			if (map->def.value_size && map->def.value_size != sz) {
 				pr_warn("map '%s': conflicting value size %u != %zd.\n",
-					map_name, map->def.value_size, (ssize_t)sz);
+					map->name, map->def.value_size, (ssize_t)sz);
 				return -EINVAL;
 			}
 			map->def.value_size = sz;
@@ -2095,44 +2040,110 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj,
 			__u32 val;
 			int err;
 
-			if (!get_map_field_int(map_name, obj->btf, m, &val))
+			if (!get_map_field_int(map->name, obj->btf, m, &val))
 				return -EINVAL;
 			pr_debug("map '%s': found pinning = %u.\n",
-				 map_name, val);
+				 map->name, val);
 
 			if (val != LIBBPF_PIN_NONE &&
 			    val != LIBBPF_PIN_BY_NAME) {
 				pr_warn("map '%s': invalid pinning value %u.\n",
-					map_name, val);
+					map->name, val);
 				return -EINVAL;
 			}
 			if (val == LIBBPF_PIN_BY_NAME) {
 				err = build_map_pin_path(map, pin_root_path);
 				if (err) {
 					pr_warn("map '%s': couldn't build pin path.\n",
-						map_name);
+						map->name);
 					return err;
 				}
 			}
 		} else {
 			if (strict) {
 				pr_warn("map '%s': unknown field '%s'.\n",
-					map_name, name);
+					map->name, name);
 				return -ENOTSUP;
 			}
 			pr_debug("map '%s': ignoring unknown field '%s'.\n",
-				 map_name, name);
+				 map->name, name);
 		}
 	}
 
 	if (map->def.type == BPF_MAP_TYPE_UNSPEC) {
-		pr_warn("map '%s': map type isn't specified.\n", map_name);
+		pr_warn("map '%s': map type isn't specified.\n", map->name);
 		return -EINVAL;
 	}
 
 	return 0;
 }
 
+static int bpf_object__init_user_btf_map(struct bpf_object *obj,
+					 const struct btf_type *sec,
+					 int var_idx, int sec_idx,
+					 const Elf_Data *data, bool strict,
+					 const char *pin_root_path)
+{
+	const struct btf_type *var, *def;
+	const struct btf_var_secinfo *vi;
+	const struct btf_var *var_extra;
+	const char *map_name;
+	struct bpf_map *map;
+
+	vi = btf_var_secinfos(sec) + var_idx;
+	var = btf__type_by_id(obj->btf, vi->type);
+	var_extra = btf_var(var);
+	map_name = btf__name_by_offset(obj->btf, var->name_off);
+
+	if (map_name == NULL || map_name[0] == '\0') {
+		pr_warn("map #%d: empty name.\n", var_idx);
+		return -EINVAL;
+	}
+	if ((__u64)vi->offset + vi->size > data->d_size) {
+		pr_warn("map '%s' BTF data is corrupted.\n", map_name);
+		return -EINVAL;
+	}
+	if (!btf_is_var(var)) {
+		pr_warn("map '%s': unexpected var kind %u.\n",
+			map_name, btf_kind(var));
+		return -EINVAL;
+	}
+	if (var_extra->linkage != BTF_VAR_GLOBAL_ALLOCATED &&
+	    var_extra->linkage != BTF_VAR_STATIC) {
+		pr_warn("map '%s': unsupported var linkage %u.\n",
+			map_name, var_extra->linkage);
+		return -EOPNOTSUPP;
+	}
+
+	def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
+	if (!btf_is_struct(def)) {
+		pr_warn("map '%s': unexpected def kind %u.\n",
+			map_name, btf_kind(var));
+		return -EINVAL;
+	}
+	if (def->size > vi->size) {
+		pr_warn("map '%s': invalid def size.\n", map_name);
+		return -EINVAL;
+	}
+
+	map = bpf_object__add_map(obj);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+	map->name = strdup(map_name);
+	if (!map->name) {
+		pr_warn("map '%s': failed to alloc map name.\n", map_name);
+		return -ENOMEM;
+	}
+	map->libbpf_type = LIBBPF_MAP_UNSPEC;
+	map->def.type = BPF_MAP_TYPE_UNSPEC;
+	map->sec_idx = sec_idx;
+	map->sec_offset = vi->offset;
+	pr_debug("map '%s': at sec_idx %d, offset %zu.\n",
+		 map_name, map->sec_idx, map->sec_offset);
+
+	return parse_btf_map_def(obj, map, def, strict, pin_root_path);
+}
+
 static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
 					  const char *pin_root_path)
 {