From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C625242046C for ; Wed, 15 Jul 2026 13:05:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784120711; cv=none; b=nsRYMD/kM+p2sb7irVAji3SAdL4UeTsmItqLk2xVHBtGVe6ouLMtIYjrp6L+sEftcSkbpOA47PggvRsRwHRglHR3+lh7PCNSXHaWlpLtLRTbjC+t6ZLR08M5wLbLDfE3tCR/xkwJ/x59HEoo2rp/TprcGc9JlqoHKkXKPbtO4Qs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784120711; c=relaxed/simple; bh=QygjsND6l65ysZQlA3+KD7oC9JBMKKiS+jkvRb2qFEY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kq20WD77a05ilDXDe+9pJCvZoC5XGY/tDYWtpoAlDfmiqv49JTCQC55ea/09/T3DcprtBrJOr10mkcbdh87tI313CDWP6712jcMKU6FyV3xAByIyr4a0/YT17N9/RDhv5Wqbx1Jgjn/HksinU06vhWHQOf4OFG8Fn4WC9cE3D18= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LQuAy20K; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="LQuAy20K" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4BAB61F000E9; Wed, 15 Jul 2026 13:05:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784120710; bh=if27uywKL5vRMrDn+r7z9C4Lnq+G/Skdb4jAZOIJv/E=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LQuAy20KL6CyYFxD4f9/RtSMMZsBWNM5kOZy26Rsg+a1PpKk/D18QQD8RmxsTgCrN DSC/l8hKCgLoJia3YVduTXM4zaSh4E9glhuA2VEJjCi7ncr3q0G7JAqJVDior2Bxpe N+wNrXDhWs+ps8vdKLk//5kbXMgwb+D4dcyGlJclbbzrBgkg1I20YkPtvlDtER2r+M VzFF8QI6ajXpxhGYnj+SOEyLgsEnp45nWSlYDfb8/wi8z/ynpWPDPYV4wyWIio7UHu WUniMYJCai/LBkWOv20dwGvK9Mxa+W0QHPENlymK0yWGuDPznt08p3LIP/FCsiO+MV Hj5d/+Y2TZGUQ== From: Puranjay Mohan To: bpf@vger.kernel.org Cc: Puranjay Mohan , "Alexei Starovoitov" , "Daniel Borkmann" , "Andrii Nakryiko" , "Martin KaFai Lau" , "Eduard Zingerman" , "Kumar Kartikeya Dwivedi" , "Song Liu" , "Yonghong Song" Subject: [PATCH bpf-next 2/4] bpf: Inline bpf_iter_num_next() kfunc Date: Wed, 15 Jul 2026 06:04:24 -0700 Message-ID: <20260715130430.318421-3-puranjay@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260715130430.318421-1-puranjay@kernel.org> References: <20260715130430.318421-1-puranjay@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit bpf_iter_num_next() is called on every iteration of a bpf_for() loop and is the hot path of the numeric open-coded iterator. It only advances the on-stack iterator state and returns a pointer to it, so open-coding it in the verifier removes a function call from each loop iteration. Inline it in bpf_fixup_kfunc_call() by replacing the call with an equivalent instruction sequence. R1 holds the pointer to the on-stack bpf_iter_num; the returned pointer to s->cur is R1 itself since s->cur is the first member. s->cur and s->end are int, so the kfunc's (s64)(s->cur + 1) >= s->end test is equivalent to a signed 32-bit comparison of (s->cur + 1) against s->end: s->cur + 1 is computed as a 32-bit int in the kfunc as well, and sign-extending both sides of a comparison of two int values does not change its result. The inlined code therefore uses a 32-bit compare and needs no sign extension. Signed-off-by: Puranjay Mohan --- kernel/bpf/verifier.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f578cebbade4f..e8b66f56598dd 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -19749,6 +19749,33 @@ static int inline_bpf_iter_num_new(struct bpf_insn *insn_buf) return 15; } +/* + * Inline bpf_iter_num_next(). R1 holds the pointer to the iterator. Keep in + * sync with the kfunc in kernel/bpf/bpf_iter.c. + */ +static int inline_bpf_iter_num_next(struct bpf_insn *insn_buf) +{ + /* + * s->cur and s->end are int, so the (s64)(s->cur + 1) >= s->end check + * is equivalent to a signed 32-bit comparison of (s->cur + 1) against + * s->end and needs no sign extension. + */ + insn_buf[0] = BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, 0); + insn_buf[1] = BPF_ALU32_IMM(BPF_ADD, BPF_REG_0, 1); + insn_buf[2] = BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 4); + /* if ((s32)(s->cur + 1) >= (s32)s->end) goto done; */ + insn_buf[3] = BPF_JMP32_REG(BPF_JSGE, BPF_REG_0, BPF_REG_2, 3); + /* s->cur++; return &s->cur; */ + insn_buf[4] = BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_0, 0); + insn_buf[5] = BPF_MOV64_REG(BPF_REG_0, BPF_REG_1); + insn_buf[6] = BPF_JMP_A(2); + /* done: s->cur = s->end = 0; return NULL; */ + insn_buf[7] = BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 0); + insn_buf[8] = BPF_MOV64_IMM(BPF_REG_0, 0); + + return 9; +} + int bpf_fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, struct bpf_insn *insn_buf, int insn_idx, int *cnt) { @@ -19880,6 +19907,8 @@ int bpf_fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, *cnt = 6; } else if (desc->func_id == special_kfunc_list[KF_bpf_iter_num_new]) { *cnt = inline_bpf_iter_num_new(insn_buf); + } else if (desc->func_id == special_kfunc_list[KF_bpf_iter_num_next]) { + *cnt = inline_bpf_iter_num_next(insn_buf); } if (env->insn_aux_data[insn_idx].arg_prog) { -- 2.53.0-Meta