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libbpf: capture value in BTF type info for BTF-defined map defs 

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 <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Andrii Nakryiko 2019-07-05 08:50:09 -07:00 committed by Daniel Borkmann
parent c5f48c9276
commit ef99b02b23
1 changed files with 31 additions and 33 deletions
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64
tools/lib/bpf/libbpf.c
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@ -1029,40 +1029,40 @@ 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);
return false;
}
if (m->offset % 32) {
pr_warning("map '%s': attr '%s': unaligned fields are not supported.\n",
map_name, name);
return false;
}
*res = *(const __u32 *)(data + m->offset / 8);
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 (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;
}
arr_info = (const void *)(arr_t + 1);
*res = arr_info->nelems;
return true;
}
@ -1075,7 +1075,6 @@ 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;
@ -1132,7 +1131,6 @@ 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++) {
@ -1145,19 +1143,19 @@ 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);
@ -1165,7 +1163,7 @@ 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);
@ -1208,7 +1206,7 @@ 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);