bpf: Compute map_btf_id during build time

For now, the field 'map_btf_id' in 'struct bpf_map_ops' for all map
types are computed during vmlinux-btf init:

  btf_parse_vmlinux() -> btf_vmlinux_map_ids_init()

It will lookup the btf_type according to the 'map_btf_name' field in
'struct bpf_map_ops'. This process can be done during build time,
thanks to Jiri's resolve_btfids.

selftest of map_ptr has passed:

  $96 map_ptr:OK
  Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 0 insertions, 40 deletions

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 4cfaf5eebecd..2f0b0440131c 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -5025,41 +5025,6 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
 	return ctx_type;
 }
 
-static const struct bpf_map_ops * const btf_vmlinux_map_ops[] = {
-#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type)
-#define BPF_LINK_TYPE(_id, _name)
-#define BPF_MAP_TYPE(_id, _ops) \
-	[_id] = &_ops,
-#include <linux/bpf_types.h>
-#undef BPF_PROG_TYPE
-#undef BPF_LINK_TYPE
-#undef BPF_MAP_TYPE
-};
-
-static int btf_vmlinux_map_ids_init(const struct btf *btf,
-				    struct bpf_verifier_log *log)
-{
-	const struct bpf_map_ops *ops;
-	int i, btf_id;
-
-	for (i = 0; i < ARRAY_SIZE(btf_vmlinux_map_ops); ++i) {
-		ops = btf_vmlinux_map_ops[i];
-		if (!ops || (!ops->map_btf_name && !ops->map_btf_id))
-			continue;
-		if (!ops->map_btf_name || !ops->map_btf_id) {
-			bpf_log(log, "map type %d is misconfigured\n", i);
-			return -EINVAL;
-		}
-		btf_id = btf_find_by_name_kind(btf, ops->map_btf_name,
-					       BTF_KIND_STRUCT);
-		if (btf_id < 0)
-			return btf_id;
-		*ops->map_btf_id = btf_id;
-	}
-
-	return 0;
-}
-
 static int btf_translate_to_vmlinux(struct bpf_verifier_log *log,
 				     struct btf *btf,
 				     const struct btf_type *t,
@@ -5125,11 +5090,6 @@ struct btf *btf_parse_vmlinux(void)
 	/* btf_parse_vmlinux() runs under bpf_verifier_lock */
 	bpf_ctx_convert.t = btf_type_by_id(btf, bpf_ctx_convert_btf_id[0]);
 
-	/* find bpf map structs for map_ptr access checking */
-	err = btf_vmlinux_map_ids_init(btf, log);
-	if (err < 0)
-		goto errout;
-
 	bpf_struct_ops_init(btf, log);
 
 	refcount_set(&btf->refcnt, 1);