Given we'll be reusing BPF array maps for global data/bss/rodata
sections, we need a way to associate BTF DataSec type as its map
value type. In usual cases we have this ugly BPF_ANNOTATE_KV_PAIR()
macro hack e.g. via
38d5d3b3d5db ("bpf: Introduce BPF_ANNOTATE_KV_PAIR")
to get initial map to type association going. While more use cases
for it are discouraged, this also won't work for global data since
the use of array map is a BPF loader detail and therefore unknown
at compilation time. For array maps with just a single entry we make
an exception in terms of BTF in that key type is declared optional
if value type is of DataSec type. The latter LLVM is guaranteed to
emit and it also aligns with how we regard global data maps as just
a plain buffer area reusing existing map facilities for allowing
things like introspection with existing tools.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
const struct btf_member *m,
u32 expected_offset, u32 expected_size);
int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t);
+bool btf_type_is_void(const struct btf_type *t);
#ifdef CONFIG_BPF_SYSCALL
const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id);
return;
}
- seq_printf(m, "%u: ", *(u32 *)key);
+ if (map->btf_key_type_id)
+ seq_printf(m, "%u: ", *(u32 *)key);
btf_type_seq_show(map->btf, map->btf_value_type_id, value, m);
seq_puts(m, "\n");
{
u32 int_data;
+ /* One exception for keyless BTF: .bss/.data/.rodata map */
+ if (btf_type_is_void(key_type)) {
+ if (map->map_type != BPF_MAP_TYPE_ARRAY ||
+ map->max_entries != 1)
+ return -EINVAL;
+
+ if (BTF_INFO_KIND(value_type->info) != BTF_KIND_DATASEC)
+ return -EINVAL;
+
+ return 0;
+ }
+
if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
return -EINVAL;
return false;
}
-static bool btf_type_is_void(const struct btf_type *t)
+bool btf_type_is_void(const struct btf_type *t)
{
return t == &btf_void;
}
u32 key_size, value_size;
int ret = 0;
- key_type = btf_type_id_size(btf, &btf_key_id, &key_size);
- if (!key_type || key_size != map->key_size)
- return -EINVAL;
+ /* Some maps allow key to be unspecified. */
+ if (btf_key_id) {
+ key_type = btf_type_id_size(btf, &btf_key_id, &key_size);
+ if (!key_type || key_size != map->key_size)
+ return -EINVAL;
+ } else {
+ key_type = btf_type_by_id(btf, 0);
+ if (!map->ops->map_check_btf)
+ return -EINVAL;
+ }
value_type = btf_type_id_size(btf, &btf_value_id, &value_size);
if (!value_type || value_size != map->value_size)
if (attr->btf_key_type_id || attr->btf_value_type_id) {
struct btf *btf;
- if (!attr->btf_key_type_id || !attr->btf_value_type_id) {
+ if (!attr->btf_value_type_id) {
err = -EINVAL;
goto free_map_nouncharge;
}