netdev - [PATCH bpf-next 3/4] bpf: Remove kfunc support in prologue and epilogue

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Message-Id: <20260119-skb-meta-bpf-emit-call-from-prologue-v1-3-e8b88d6430d8@cloudflare.com>
Date: Mon, 19 Jan 2026 20:53:53 +0100
From: Jakub Sitnicki <jakub@...udflare.com>
To: bpf@...r.kernel.org
Cc: Alexei Starovoitov <ast@...nel.org>, 
 Daniel Borkmann <daniel@...earbox.net>, 
 John Fastabend <john.fastabend@...il.com>, 
 Andrii Nakryiko <andrii@...nel.org>, 
 Martin KaFai Lau <martin.lau@...ux.dev>, 
 Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
 Yonghong Song <yonghong.song@...ux.dev>, KP Singh <kpsingh@...nel.org>, 
 Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
 Jiri Olsa <jolsa@...nel.org>, Amery Hung <ameryhung@...il.com>, 
 netdev@...r.kernel.org, kernel-team@...udflare.com
Subject: [PATCH bpf-next 3/4] bpf: Remove kfunc support in prologue and
 epilogue

Remove add_kfunc_in_insns() and its call sites in convert_ctx_accesses().
This function was used to register kfuncs found in prologue and epilogue
instructions, but is no longer needed now that we use direct helper calls
via BPF_EMIT_CALL instead.

Signed-off-by: Jakub Sitnicki <jakub@...udflare.com>
---
 kernel/bpf/verifier.c | 25 +------------------------
 1 file changed, 1 insertion(+), 24 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 15694a40ca02..b04b63c9b777 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3453,21 +3453,6 @@ bpf_jit_find_kfunc_model(const struct bpf_prog *prog,
 	return res ? &res->func_model : NULL;
 }
 
-static int add_kfunc_in_insns(struct bpf_verifier_env *env,
-			      struct bpf_insn *insn, int cnt)
-{
-	int i, ret;
-
-	for (i = 0; i < cnt; i++, insn++) {
-		if (bpf_pseudo_kfunc_call(insn)) {
-			ret = add_kfunc_call(env, insn->imm, insn->off);
-			if (ret < 0)
-				return ret;
-		}
-	}
-	return 0;
-}
-
 static int add_subprog_and_kfunc(struct bpf_verifier_env *env)
 {
 	struct bpf_subprog_info *subprog = env->subprog_info;
@@ -21823,7 +21808,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 {
 	struct bpf_subprog_info *subprogs = env->subprog_info;
 	const struct bpf_verifier_ops *ops = env->ops;
-	int i, cnt, size, ctx_field_size, ret, delta = 0, epilogue_cnt = 0;
+	int i, cnt, size, ctx_field_size, delta = 0, epilogue_cnt = 0;
 	const int insn_cnt = env->prog->len;
 	struct bpf_insn *epilogue_buf = env->epilogue_buf;
 	struct bpf_insn *insn_buf = env->insn_buf;
@@ -21852,10 +21837,6 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 				return -ENOMEM;
 			env->prog = new_prog;
 			delta += cnt - 1;
-
-			ret = add_kfunc_in_insns(env, epilogue_buf, epilogue_cnt - 1);
-			if (ret < 0)
-				return ret;
 		}
 	}
 
@@ -21877,10 +21858,6 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 			env->prog = new_prog;
 			delta += cnt - 1;
 
-			ret = add_kfunc_in_insns(env, insn_buf, cnt - 1);
-			if (ret < 0)
-				return ret;
-
 			mark_helper_calls_finalized(env, 0, cnt - 1);
 		}
 	}

-- 
2.43.0