From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47999C606D2 for ; Mon, 8 Jul 2019 21:44:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2861A216FD for ; Mon, 8 Jul 2019 21:44:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404846AbfGHVop convert rfc822-to-8bit (ORCPT ); Mon, 8 Jul 2019 17:44:45 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:6130 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730589AbfGHVop (ORCPT ); Mon, 8 Jul 2019 17:44:45 -0400 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x68LWm2L079431 for ; Mon, 8 Jul 2019 17:44:44 -0400 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0a-001b2d01.pphosted.com with ESMTP id 2tmbtrv72t-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 08 Jul 2019 17:44:43 -0400 Received: from localhost by e06smtp01.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 8 Jul 2019 22:44:41 +0100 Received: from b06cxnps4074.portsmouth.uk.ibm.com (9.149.109.196) by e06smtp01.uk.ibm.com (192.168.101.131) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 8 Jul 2019 22:44:38 +0100 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x68Libdu49938670 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 8 Jul 2019 21:44:37 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 73FC9A4040; Mon, 8 Jul 2019 21:44:37 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DAF81A4055; Mon, 8 Jul 2019 21:44:36 +0000 (GMT) Received: from [9.145.50.9] (unknown [9.145.50.9]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 8 Jul 2019 21:44:36 +0000 (GMT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) Subject: Re: [PATCH bpf-next] selftests/bpf: make verifier loop tests arch independent From: Ilya Leoshkevich In-Reply-To: <20190708212012.GA9509@mini-arch> Date: Mon, 8 Jul 2019 23:44:36 +0200 Cc: Y Song , Stanislav Fomichev , netdev , bpf , David Miller , Alexei Starovoitov , Daniel Borkmann Content-Transfer-Encoding: 8BIT References: <20190703205100.142904-1-sdf@google.com> <20190708161338.GC29524@mini-arch> <99593C98-5DEC-4B18-AE6D-271DD8A8A7F6@linux.ibm.com> <20190708212012.GA9509@mini-arch> To: Stanislav Fomichev X-Mailer: Apple Mail (2.3445.9.1) X-TM-AS-GCONF: 00 x-cbid: 19070821-4275-0000-0000-0000034A5043 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19070821-4276-0000-0000-0000385A78BD Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-07-08_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1907080269 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org > Am 08.07.2019 um 23:20 schrieb Stanislav Fomichev : > > On 07/08, Ilya Leoshkevich wrote: >> >> >>> Am 08.07.2019 um 18:13 schrieb Stanislav Fomichev : >>> >>> On 07/03, Y Song wrote: >>>> On Wed, Jul 3, 2019 at 1:51 PM Stanislav Fomichev wrote: >>>>> >>>>> Take the first x bytes of pt_regs for scalability tests, there is >>>>> no real reason we need x86 specific rax. >>>>> >>>>> Signed-off-by: Stanislav Fomichev >>>>> --- >>>>> tools/testing/selftests/bpf/progs/loop1.c | 3 ++- >>>>> tools/testing/selftests/bpf/progs/loop2.c | 3 ++- >>>>> tools/testing/selftests/bpf/progs/loop3.c | 3 ++- >>>>> 3 files changed, 6 insertions(+), 3 deletions(-) >>>>> >>>>> diff --git a/tools/testing/selftests/bpf/progs/loop1.c b/tools/testing/selftests/bpf/progs/loop1.c >>>>> index dea395af9ea9..d530c61d2517 100644 >>>>> --- a/tools/testing/selftests/bpf/progs/loop1.c >>>>> +++ b/tools/testing/selftests/bpf/progs/loop1.c >>>>> @@ -14,11 +14,12 @@ SEC("raw_tracepoint/kfree_skb") >>>>> int nested_loops(volatile struct pt_regs* ctx) >>>>> { >>>>> int i, j, sum = 0, m; >>>>> + volatile int *any_reg = (volatile int *)ctx; >>>>> >>>>> for (j = 0; j < 300; j++) >>>>> for (i = 0; i < j; i++) { >>>>> if (j & 1) >>>>> - m = ctx->rax; >>>>> + m = *any_reg; >>>> >>>> I agree. ctx->rax here is only to generate some operations, which >>>> cannot be optimized away by the compiler. dereferencing a volatile >>>> pointee may just serve that purpose. >>>> >>>> Comparing the byte code generated with ctx->rax and *any_reg, they are >>>> slightly different. Using *any_reg is slighly worse, but this should >>>> be still okay for the test. >>>> >>>>> else >>>>> m = j; >>>>> sum += i * m; >>>>> diff --git a/tools/testing/selftests/bpf/progs/loop2.c b/tools/testing/selftests/bpf/progs/loop2.c >>>>> index 0637bd8e8bcf..91bb89d901e3 100644 >>>>> --- a/tools/testing/selftests/bpf/progs/loop2.c >>>>> +++ b/tools/testing/selftests/bpf/progs/loop2.c >>>>> @@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb") >>>>> int while_true(volatile struct pt_regs* ctx) >>>>> { >>>>> int i = 0; >>>>> + volatile int *any_reg = (volatile int *)ctx; >>>>> >>>>> while (true) { >>>>> - if (ctx->rax & 1) >>>>> + if (*any_reg & 1) >>>>> i += 3; >>>>> else >>>>> i += 7; >>>>> diff --git a/tools/testing/selftests/bpf/progs/loop3.c b/tools/testing/selftests/bpf/progs/loop3.c >>>>> index 30a0f6cba080..3a7f12d7186c 100644 >>>>> --- a/tools/testing/selftests/bpf/progs/loop3.c >>>>> +++ b/tools/testing/selftests/bpf/progs/loop3.c >>>>> @@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb") >>>>> int while_true(volatile struct pt_regs* ctx) >>>>> { >>>>> __u64 i = 0, sum = 0; >>>>> + volatile __u64 *any_reg = (volatile __u64 *)ctx; >>>>> do { >>>>> i++; >>>>> - sum += ctx->rax; >>>>> + sum += *any_reg; >>>>> } while (i < 0x100000000ULL); >>>>> return sum; >>>>> } >>>>> -- >>>>> 2.22.0.410.gd8fdbe21b5-goog >>>> >>>> Ilya Leoshkevich (iii@linux.ibm.com, cc'ed) has another patch set >>>> trying to solve this problem by introducing s360 arch register access >>>> macros. I guess for now that patch set is not needed any more? >>> Oh, I missed them. Do they fix the tests for other (non-s360) arches as >>> well? I was trying to fix the issue by not depending on any arch >>> specific stuff because the test really doesn't care :-) >> >> They are supposed to work for everything that defines PT_REGS_RC in >> bpf_helpers.h, but I have to admit I tested only x86_64 and s390. >> >> The main source of problems with my approach were mismatching definitions >> of struct pt_regs for userspace and kernel, and because of that there was >> some tweaking required for both arches. I will double check how it looks >> for others (arm, mips, ppc, sparc) tomorrow. > Thanks, I've tested your patches and they fix my issue as well. So you > can have my Tested-by if we'd go with your approach. > > One thing I don't understand is: why do you add 'ifdef __KERNEL__' to > the bpf_helpers.h for x86 case? Who is using bpf_helpers.h with > __KERNEL__ defined? Is it perf? That’s samples/bpf. Also, there is a modified copy of it in bcc (src/cc/export/helpers.h), which also gets built with __KERNEL__. Best regards, Ilya