From patchwork Fri Jun 10 15:55:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hari Bathini X-Patchwork-Id: 12877738 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9BEA6C433EF for ; Fri, 10 Jun 2022 15:56:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243656AbiFJP4s (ORCPT ); Fri, 10 Jun 2022 11:56:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345739AbiFJP4q (ORCPT ); Fri, 10 Jun 2022 11:56:46 -0400 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A90AA1D30CD; Fri, 10 Jun 2022 08:56:44 -0700 (PDT) Received: from pps.filterd (m0098409.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 25AFtrEf011189; Fri, 10 Jun 2022 15:56:15 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding; s=pp1; bh=SgpFwGA9RTkKfBKq1OguzDdqQthzqHGegbMtmXtjgWc=; b=ASBtC/NZaE4FWmn68UgoBgMFhIXXUSbUxVd+yGdutH9+61KY2cIR2sKEOMvZH1vzo75a H1JxtccPz68puCo/BTyBmQTuPobARSjJCuSDzQAfoN/C8sm/nh7ss1EIHC2FHstAP2gi 0oqUj7iI4CeZsKLjTZXfNuAgR63LMQ1I1Ros+YhpbDxG2VdLQ1427Oi7gYE53yHWJcWW mThrldBhFfX4XHNsH2eZqw3/M0df36QJYrOeOkmwD7ipe5u5bjM/Uo5OUSL6wd+15cGM nk2o7KqmpViNCxBZL6JMadEJjfb9AFiMPSwnEKKbswVqGBmXSeSNs28kWQnPEKRIUNw9 eg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3gm91gr08m-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 10 Jun 2022 15:56:15 +0000 Received: from m0098409.ppops.net (m0098409.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 25AFuEck011740; Fri, 10 Jun 2022 15:56:14 GMT Received: from ppma04ams.nl.ibm.com (63.31.33a9.ip4.static.sl-reverse.com [169.51.49.99]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3gm91gr080-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 10 Jun 2022 15:56:14 +0000 Received: from pps.filterd (ppma04ams.nl.ibm.com [127.0.0.1]) by ppma04ams.nl.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 25AFoWb9021291; Fri, 10 Jun 2022 15:56:11 GMT Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by ppma04ams.nl.ibm.com with ESMTP id 3gfy19geew-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 10 Jun 2022 15:56:11 +0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 25AFu9e722413814 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 10 Jun 2022 15:56:09 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4296D4C040; Fri, 10 Jun 2022 15:56:09 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8E5434C044; Fri, 10 Jun 2022 15:56:05 +0000 (GMT) Received: from hbathini-workstation.in.ibm.com (unknown [9.203.106.231]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 10 Jun 2022 15:56:05 +0000 (GMT) From: Hari Bathini To: bpf@vger.kernel.org, linuxppc-dev Cc: Michael Ellerman , "Naveen N. Rao" , Christophe Leroy , netdev@vger.kernel.org, Benjamin Herrenschmidt , Paul Mackerras , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Jordan Niethe , Russell Currey Subject: [PATCH v2 3/5] bpf ppc64: Add instructions for atomic_[cmp]xchg Date: Fri, 10 Jun 2022 21:25:50 +0530 Message-Id: <20220610155552.25892-4-hbathini@linux.ibm.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220610155552.25892-1-hbathini@linux.ibm.com> References: <20220610155552.25892-1-hbathini@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: QBDuw1EA2QflXNjpUmrSV6cp1G3QdAKg X-Proofpoint-ORIG-GUID: Xup1eUiqYZ7I8PmvCo8BMf9aJDJ2N6w7 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.874,Hydra:6.0.517,FMLib:17.11.64.514 definitions=2022-06-10_06,2022-06-09_02,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 adultscore=0 lowpriorityscore=0 malwarescore=0 bulkscore=0 phishscore=0 priorityscore=1501 mlxscore=0 spamscore=0 mlxlogscore=999 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2204290000 definitions=main-2206100061 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net This adds two atomic opcodes BPF_XCHG and BPF_CMPXCHG on ppc64, both of which include the BPF_FETCH flag. The kernel's atomic_cmpxchg operation fundamentally has 3 operands, but we only have two register fields. Therefore the operand we compare against (the kernel's API calls it 'old') is hard-coded to be BPF_REG_R0. Also, kernel's atomic_cmpxchg returns the previous value at dst_reg + off. JIT the same for BPF too with return value put in BPF_REG_0. BPF_REG_R0 = atomic_cmpxchg(dst_reg + off, BPF_REG_R0, src_reg); Signed-off-by: Hari Bathini --- Changes in v2: * Moved variable declaration to avoid late declaration error on some compilers. * Added an optimization for 32-bit cmpxchg with regard to commit see commit 39491867ace5. arch/powerpc/net/bpf_jit_comp64.c | 39 +++++++++++++++++++++++++++---- 1 file changed, 34 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index c53236b3a8b1..29ee306d6302 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -360,6 +360,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * u32 size = BPF_SIZE(code); u32 tmp1_reg = bpf_to_ppc(TMP_REG_1); u32 tmp2_reg = bpf_to_ppc(TMP_REG_2); + u32 save_reg, ret_reg; s16 off = insn[i].off; s32 imm = insn[i].imm; bool func_addr_fixed; @@ -778,6 +779,9 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * */ case BPF_STX | BPF_ATOMIC | BPF_W: case BPF_STX | BPF_ATOMIC | BPF_DW: + save_reg = tmp2_reg; + ret_reg = src_reg; + /* Get offset into TMP_REG_1 */ EMIT(PPC_RAW_LI(tmp1_reg, off)); tmp_idx = ctx->idx * 4; @@ -808,6 +812,24 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * case BPF_XOR | BPF_FETCH: EMIT(PPC_RAW_XOR(tmp2_reg, tmp2_reg, src_reg)); break; + case BPF_CMPXCHG: + /* + * Return old value in BPF_REG_0 for BPF_CMPXCHG & + * in src_reg for other cases. + */ + ret_reg = bpf_to_ppc(BPF_REG_0); + + /* Compare with old value in BPF_R0 */ + if (size == BPF_DW) + EMIT(PPC_RAW_CMPD(bpf_to_ppc(BPF_REG_0), tmp2_reg)); + else + EMIT(PPC_RAW_CMPW(bpf_to_ppc(BPF_REG_0), tmp2_reg)); + /* Don't set if different from old value */ + PPC_BCC_SHORT(COND_NE, (ctx->idx + 3) * 4); + fallthrough; + case BPF_XCHG: + save_reg = src_reg; + break; default: pr_err_ratelimited( "eBPF filter atomic op code %02x (@%d) unsupported\n", @@ -817,15 +839,22 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context * /* store new value */ if (size == BPF_DW) - EMIT(PPC_RAW_STDCX(tmp2_reg, tmp1_reg, dst_reg)); + EMIT(PPC_RAW_STDCX(save_reg, tmp1_reg, dst_reg)); else - EMIT(PPC_RAW_STWCX(tmp2_reg, tmp1_reg, dst_reg)); + EMIT(PPC_RAW_STWCX(save_reg, tmp1_reg, dst_reg)); /* we're done if this succeeded */ PPC_BCC_SHORT(COND_NE, tmp_idx); - /* For the BPF_FETCH variant, get old value into src_reg */ - if (imm & BPF_FETCH) - EMIT(PPC_RAW_MR(src_reg, _R0)); + if (imm & BPF_FETCH) { + EMIT(PPC_RAW_MR(ret_reg, _R0)); + /* + * Skip unnecessary zero-extension for 32-bit cmpxchg. + * For context, see commit 39491867ace5. + */ + if (size != BPF_DW && imm == BPF_CMPXCHG && + insn_is_zext(&insn[i + 1])) + addrs[++i] = ctx->idx * 4; + } break; /*