bpf: Skip anonymous types in type lookup for performance

Currently, vmlinux and kernel module BTFs are unconditionally
sorted during the build phase, with named types placed at the
end. Thus, anonymous types should be skipped when starting the
search. In my vmlinux BTF, the number of anonymous types is
61,747, which means the loop count can be reduced by 61,747.

Signed-off-by: Donglin Peng <pengdonglin@xiaomi.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20260109130003.3313716-9-dolinux.peng@gmail.com

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index d5b3a37c8560dea5393052065efc00cc3ce7de64..364dd84bfc5a2b542b30beb86eacf9dcdb36bb31 100644 (file)
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3534,7 +3534,8 @@ const char *btf_find_decl_tag_value(const struct btf *btf, const struct btf_type
        const struct btf_type *t;
        int len, id;
 
-       id = btf_find_next_decl_tag(btf, pt, comp_idx, tag_key, 0);
+       id = btf_find_next_decl_tag(btf, pt, comp_idx, tag_key,
+                                   btf_named_start_id(btf, false) - 1);
        if (id < 0)
                return ERR_PTR(id);
 
@@ -7844,12 +7845,13 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
                        tname);
                return -EINVAL;
        }
+
        /* Convert BTF function arguments into verifier types.
         * Only PTR_TO_CTX and SCALAR are supported atm.
         */
        for (i = 0; i < nargs; i++) {
                u32 tags = 0;
-               int id = 0;
+               int id = btf_named_start_id(btf, false) - 1;
 
                /* 'arg:<tag>' decl_tag takes precedence over derivation of
                 * register type from BTF type itself
@@ -9338,7 +9340,7 @@ bpf_core_find_cands(struct bpf_core_ctx *ctx, u32 local_type_id)
        }
 
        /* Attempt to find target candidates in vmlinux BTF first */
-       cands = bpf_core_add_cands(cands, main_btf, 1);
+       cands = bpf_core_add_cands(cands, main_btf, btf_named_start_id(main_btf, true));
        if (IS_ERR(cands))
                return ERR_CAST(cands);
 
@@ -9370,7 +9372,7 @@ check_modules:
                 */
                btf_get(mod_btf);
                spin_unlock_bh(&btf_idr_lock);
-               cands = bpf_core_add_cands(cands, mod_btf, btf_nr_types(main_btf));
+               cands = bpf_core_add_cands(cands, mod_btf, btf_named_start_id(mod_btf, true));
                btf_put(mod_btf);
                if (IS_ERR(cands))
                        return ERR_CAST(cands);

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 092003cc784175512d9a8cee269b87073af6e32d..45733bae271d380a3c8e2f93d7b64a3868d25220 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -20687,12 +20687,7 @@ static int find_btf_percpu_datasec(struct btf *btf)
         * types to look at only module's own BTF types.
         */
        n = btf_nr_types(btf);
-       if (btf_is_module(btf))
-               i = btf_nr_types(btf_vmlinux);
-       else
-               i = 1;
-
-       for(; i < n; i++) {
+       for (i = btf_named_start_id(btf, true); i < n; i++) {
                t = btf_type_by_id(btf, i);
                if (BTF_INFO_KIND(t->info) != BTF_KIND_DATASEC)
                        continue;