linux-kernel - [PATCH bpf-next v11 08/11] bpf: Skip anonymous types in type lookup for performance

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Message-Id: <20260108031645.1350069-9-dolinux.peng@gmail.com>
Date: Thu,  8 Jan 2026 11:16:42 +0800
From: Donglin Peng <dolinux.peng@...il.com>
To: ast@...nel.org,
	andrii.nakryiko@...il.com,
	eddyz87@...il.com
Cc: zhangxiaoqin@...omi.com,
	ihor.solodrai@...ux.dev,
	linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org,
	Donglin Peng <pengdonglin@...omi.com>,
	Alan Maguire <alan.maguire@...cle.com>
Subject: [PATCH bpf-next v11 08/11] bpf: Skip anonymous types in type lookup for performance

From: Donglin Peng <pengdonglin@...omi.com>

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.

Cc: Eduard Zingerman <eddyz87@...il.com>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc: Alan Maguire <alan.maguire@...cle.com>
Cc: Ihor Solodrai <ihor.solodrai@...ux.dev>
Cc: Xiaoqin Zhang <zhangxiaoqin@...omi.com>
Signed-off-by: Donglin Peng <pengdonglin@...omi.com>
Acked-by: Eduard Zingerman <eddyz87@...il.com>
---
 kernel/bpf/btf.c      | 10 ++++++----
 kernel/bpf/verifier.c |  7 +------
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 12eecf59d71f..686dbe18a97a 100644
--- 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
@@ -9331,7 +9333,7 @@ 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);
 
@@ -9363,7 +9365,7 @@ bpf_core_find_cands(struct bpf_core_ctx *ctx, u32 local_type_id)
 		 */
 		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 9394b0de2ef0..05fa2e9181f5 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -20642,12 +20642,7 @@ 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;
-- 
2.34.1