[PATCH v3 bpf-next 1/4] libbpf: capture value in BTF type info for BTF-defined map defs
From: Andrii Nakryiko <hidden>
Date: 2019-07-03 19:06:16
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [library] (libbpf), the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
Change BTF-defined map definitions to capture compile-time integer values as part of BTF type definition, to avoid split of key/value type information and actual type/size/flags initialization for maps. Signed-off-by: Andrii Nakryiko <redacted> --- tools/lib/bpf/libbpf.c | 58 ++++++++++++++++++++---------------------- 1 file changed, 28 insertions(+), 30 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 4907997289e9..fad8901ee774 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c@@ -1028,40 +1028,40 @@ static const struct btf_type *skip_mods_and_typedefs(const struct btf *btf, } } -static bool get_map_field_int(const char *map_name, - const struct btf *btf, +/* + * Fetch integer attribute of BTF map definition. Such attributes are + * represented using a pointer to an array, in which dimensionality of array + * encodes specified integer value. E.g., int (*type)[BPF_MAP_TYPE_ARRAY]; + * encodes `type => BPF_MAP_TYPE_ARRAY` key/value pair completely using BTF + * type definition, while using only sizeof(void *) space in ELF data section. + */ +static bool get_map_field_int(const char *map_name, const struct btf *btf, const struct btf_type *def, - const struct btf_member *m, - const void *data, __u32 *res) { + const struct btf_member *m, __u32 *res) { const struct btf_type *t = skip_mods_and_typedefs(btf, m->type); const char *name = btf__name_by_offset(btf, m->name_off); - __u32 int_info = *(const __u32 *)(const void *)(t + 1); + const struct btf_array *arr_info; + const struct btf_type *arr_t; - if (BTF_INFO_KIND(t->info) != BTF_KIND_INT) { - pr_warning("map '%s': attr '%s': expected INT, got %u.\n", + if (BTF_INFO_KIND(t->info) != BTF_KIND_PTR) { + pr_warning("map '%s': attr '%s': expected PTR, got %u.\n", map_name, name, BTF_INFO_KIND(t->info)); return false; } - if (t->size != 4 || BTF_INT_BITS(int_info) != 32 || - BTF_INT_OFFSET(int_info)) { - pr_warning("map '%s': attr '%s': expected 32-bit non-bitfield integer, " - "got %u-byte (%d-bit) one with bit offset %d.\n", - map_name, name, t->size, BTF_INT_BITS(int_info), - BTF_INT_OFFSET(int_info)); - return false; - } - if (BTF_INFO_KFLAG(def->info) && BTF_MEMBER_BITFIELD_SIZE(m->offset)) { - pr_warning("map '%s': attr '%s': bitfield is not supported.\n", - map_name, name); + + arr_t = btf__type_by_id(btf, t->type); + if (!arr_t) { + pr_warning("map '%s': attr '%s': type [%u] not found.\n", + map_name, name, t->type); return false; } - if (m->offset % 32) { - pr_warning("map '%s': attr '%s': unaligned fields are not supported.\n", - map_name, name); + if (BTF_INFO_KIND(arr_t->info) != BTF_KIND_ARRAY) { + pr_warning("map '%s': attr '%s': expected ARRAY, got %u.\n", + map_name, name, BTF_INFO_KIND(arr_t->info)); return false; } - - *res = *(const __u32 *)(data + m->offset / 8); + arr_info = (const void *)(arr_t + 1); + *res = arr_info->nelems; return true; }
@@ -1074,7 +1074,6 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj, const struct btf_var_secinfo *vi; const struct btf_var *var_extra; const struct btf_member *m; - const void *def_data; const char *map_name; struct bpf_map *map; int vlen, i;
@@ -1131,7 +1130,6 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj, pr_debug("map '%s': at sec_idx %d, offset %zu.\n", map_name, map->sec_idx, map->sec_offset); - def_data = data->d_buf + vi->offset; vlen = BTF_INFO_VLEN(def->info); m = (const void *)(def + 1); for (i = 0; i < vlen; i++, m++) {
@@ -1144,19 +1142,19 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj, } if (strcmp(name, "type") == 0) { if (!get_map_field_int(map_name, obj->btf, def, m, - def_data, &map->def.type)) + &map->def.type)) return -EINVAL; pr_debug("map '%s': found type = %u.\n", map_name, map->def.type); } else if (strcmp(name, "max_entries") == 0) { if (!get_map_field_int(map_name, obj->btf, def, m, - def_data, &map->def.max_entries)) + &map->def.max_entries)) return -EINVAL; pr_debug("map '%s': found max_entries = %u.\n", map_name, map->def.max_entries); } else if (strcmp(name, "map_flags") == 0) { if (!get_map_field_int(map_name, obj->btf, def, m, - def_data, &map->def.map_flags)) + &map->def.map_flags)) return -EINVAL; pr_debug("map '%s': found map_flags = %u.\n", map_name, map->def.map_flags);
@@ -1164,7 +1162,7 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj, __u32 sz; if (!get_map_field_int(map_name, obj->btf, def, m, - def_data, &sz)) + &sz)) return -EINVAL; pr_debug("map '%s': found key_size = %u.\n", map_name, sz);
@@ -1207,7 +1205,7 @@ static int bpf_object__init_user_btf_map(struct bpf_object *obj, __u32 sz; if (!get_map_field_int(map_name, obj->btf, def, m, - def_data, &sz)) + &sz)) return -EINVAL; pr_debug("map '%s': found value_size = %u.\n", map_name, sz);
--
2.17.1