bpf: Remove btf_id helpers resolving

Now when we moved the helpers btf_id arrays into .BTF_ids section,
we can remove the code that resolve those IDs in runtime.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200711215329.41165-6-jolsa@kernel.org

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 4c3007f..71140b7 100644 (file)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -4079,96 +4079,17 @@ error:
        return -EINVAL;
 }
 
-static int __btf_resolve_helper_id(struct bpf_verifier_log *log, void *fn,
-                                  int arg)
-{
-       char fnname[KSYM_SYMBOL_LEN + 4] = "btf_";
-       const struct btf_param *args;
-       const struct btf_type *t;
-       const char *tname, *sym;
-       u32 btf_id, i;
-
-       if (IS_ERR(btf_vmlinux)) {
-               bpf_log(log, "btf_vmlinux is malformed\n");
-               return -EINVAL;
-       }
-
-       sym = kallsyms_lookup((long)fn, NULL, NULL, NULL, fnname + 4);
-       if (!sym) {
-               bpf_log(log, "kernel doesn't have kallsyms\n");
-               return -EFAULT;
-       }
-
-       for (i = 1; i <= btf_vmlinux->nr_types; i++) {
-               t = btf_type_by_id(btf_vmlinux, i);
-               if (BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF)
-                       continue;
-               tname = __btf_name_by_offset(btf_vmlinux, t->name_off);
-               if (!strcmp(tname, fnname))
-                       break;
-       }
-       if (i > btf_vmlinux->nr_types) {
-               bpf_log(log, "helper %s type is not found\n", fnname);
-               return -ENOENT;
-       }
-
-       t = btf_type_by_id(btf_vmlinux, t->type);
-       if (!btf_type_is_ptr(t))
-               return -EFAULT;
-       t = btf_type_by_id(btf_vmlinux, t->type);
-       if (!btf_type_is_func_proto(t))
-               return -EFAULT;
-
-       args = (const struct btf_param *)(t + 1);
-       if (arg >= btf_type_vlen(t)) {
-               bpf_log(log, "bpf helper %s doesn't have %d-th argument\n",
-                       fnname, arg);
-               return -EINVAL;
-       }
-
-       t = btf_type_by_id(btf_vmlinux, args[arg].type);
-       if (!btf_type_is_ptr(t) || !t->type) {
-               /* anything but the pointer to struct is a helper config bug */
-               bpf_log(log, "ARG_PTR_TO_BTF is misconfigured\n");
-               return -EFAULT;
-       }
-       btf_id = t->type;
-       t = btf_type_by_id(btf_vmlinux, t->type);
-       /* skip modifiers */
-       while (btf_type_is_modifier(t)) {
-               btf_id = t->type;
-               t = btf_type_by_id(btf_vmlinux, t->type);
-       }
-       if (!btf_type_is_struct(t)) {
-               bpf_log(log, "ARG_PTR_TO_BTF is not a struct\n");
-               return -EFAULT;
-       }
-       bpf_log(log, "helper %s arg%d has btf_id %d struct %s\n", fnname + 4,
-               arg, btf_id, __btf_name_by_offset(btf_vmlinux, t->name_off));
-       return btf_id;
-}
-
 int btf_resolve_helper_id(struct bpf_verifier_log *log,
                          const struct bpf_func_proto *fn, int arg)
 {
-       int *btf_id = &fn->btf_id[arg];
-       int ret;
+       int id;
 
        if (fn->arg_type[arg] != ARG_PTR_TO_BTF_ID)
                return -EINVAL;
-
-       ret = READ_ONCE(*btf_id);
-       if (ret)
-               return ret;
-       /* ok to race the search. The result is the same */
-       ret = __btf_resolve_helper_id(log, fn->func, arg);
-       if (!ret) {
-               /* Function argument cannot be type 'void' */
-               bpf_log(log, "BTF resolution bug\n");
-               return -EFAULT;
-       }
-       WRITE_ONCE(*btf_id, ret);
-       return ret;
+       id = fn->btf_id[arg];
+       if (!id || id > btf_vmlinux->nr_types)
+               return -EINVAL;
+       return id;
 }
 
 static int __get_type_size(struct btf *btf, u32 btf_id,