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=-8.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MSGID_FROM_MTA_HEADER,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 02912C4338F for ; Thu, 29 Jul 2021 15:50:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFB3D60F46 for ; Thu, 29 Jul 2021 15:50:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237656AbhG2PuW (ORCPT ); Thu, 29 Jul 2021 11:50:22 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:3768 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S229602AbhG2PuW (ORCPT ); Thu, 29 Jul 2021 11:50:22 -0400 Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.16.0.43/8.16.0.43) with SMTP id 16TFnJ25009941; Thu, 29 Jul 2021 08:50:06 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=subject : to : cc : references : from : message-id : date : in-reply-to : content-type : content-transfer-encoding : mime-version; s=facebook; bh=F2p2E4rcmRbAuCcWUe6UA98WELVMiUCEiChxeUk7cQI=; b=EUt0KeRauGwKKqSuHSBwf7dfMsSBct3DKAsyeEfBFZM6kbzY9tn3E6ABLf4MUfdGm5LU LzKSatFgBIP2CmMqsuY28doBz1GCVTlZ7ESlRvpzPBr9qDjkuJmTZqOkdIW1Tw6DlilC 45LoG+r/XU42td7LDUPFcsgU8005CTk3wGE= Received: from mail.thefacebook.com ([163.114.132.120]) by m0089730.ppops.net with ESMTP id 3a37bf8h6v-6 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Thu, 29 Jul 2021 08:50:06 -0700 Received: from NAM12-DM6-obe.outbound.protection.outlook.com (100.104.98.9) by o365-in.thefacebook.com (100.104.94.199) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 29 Jul 2021 08:50:05 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=YS00gdAX4xH/CTurKmRDBumZh35GgRiNnskkdmNZXizViELt+qr396Enm45fNwgKbqrZQ8R19f5PZngzeN9HJVaWtlCzelsSTO+KYi2IKAulKtLHQPs08BSHM8nj36uaQYJr9StdwzvTRlhApTDjysiHeqA1R0dRHyJckGiIQt4E5kGi2OnFJjlUUVF4C0mwSyK9af7dzBpgHD/d9eijCMuOS/tpYKDl6Qa0ivUyPU6ykZjfAulgIBw3s3LP/DUqcV3ktXS2EMX4c66P8yHv0Q1+XjzNbH8YfJnlQKXDlqkAhzDiCy371WqLCpveXVs/dlZ1Q50dsLIc/WMjWkr8zg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=F2p2E4rcmRbAuCcWUe6UA98WELVMiUCEiChxeUk7cQI=; b=Au/GM8MT2QhINnaDcTE/rfNRMnkMpy7of7cTfkBCoQIMnCvcdXv4Q403JMrBhy5hZrSl9CoQUxvH0mANY2HSVwdF1ak3P2diFyTtpELX86oLvIwmUhD0s6a8bNLPsiBduTE3GCoO9cGWI7FMAvj+QYd83TlYzLri5K/rkcRDp1opi1eoJKi7KyjqahzrFm4FNPeK1sn6PA6g3nFIYTYVQwbPmmZou56ZE9yDLNApidW0s7zTlF2ZkT+s5DLNSSMDZ46WlgJEB6QqrD3Ha+PdzJgfhrPjVxcjbBFqAFzAZI0QALY7z1fj9umvGxhvpT247h3FrjLv3hXkoNh/SZ5xDg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=fb.com; dmarc=pass action=none header.from=fb.com; dkim=pass header.d=fb.com; arc=none Authentication-Results: vger.kernel.org; dkim=none (message not signed) header.d=none;vger.kernel.org; dmarc=none action=none header.from=fb.com; Received: from SN6PR1501MB2064.namprd15.prod.outlook.com (2603:10b6:805:d::27) by SA1PR15MB4919.namprd15.prod.outlook.com (2603:10b6:806:1d2::11) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4373.20; Thu, 29 Jul 2021 15:50:04 +0000 Received: from SN6PR1501MB2064.namprd15.prod.outlook.com ([fe80::c143:fac2:85b4:14cb]) by SN6PR1501MB2064.namprd15.prod.outlook.com ([fe80::c143:fac2:85b4:14cb%7]) with mapi id 15.20.4373.021; Thu, 29 Jul 2021 15:50:04 +0000 Subject: Re: [PATCH 10/14] bpf/tests: Add branch conversion JIT test To: Johan Almbladh CC: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , John Fastabend , KP Singh , Tony Ambardar , Networking , bpf References: <20210728170502.351010-1-johan.almbladh@anyfinetworks.com> <20210728170502.351010-11-johan.almbladh@anyfinetworks.com> <6c362bc2-e4cf-321b-89fb-4e20276c0d73@fb.com> From: Yonghong Song Message-ID: <0feebbb6-7ba7-fe6e-1854-dd1cebfaf1f2@fb.com> Date: Thu, 29 Jul 2021 08:50:01 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BY5PR13CA0014.namprd13.prod.outlook.com (2603:10b6:a03:180::27) To SN6PR1501MB2064.namprd15.prod.outlook.com (2603:10b6:805:d::27) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [IPv6:2620:10d:c085:21d6::11d1] (2620:10d:c090:400::5:81b5) by BY5PR13CA0014.namprd13.prod.outlook.com (2603:10b6:a03:180::27) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4394.6 via Frontend Transport; Thu, 29 Jul 2021 15:50:03 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 09beaa7d-9b9e-4dea-43c0-08d952a88801 X-MS-TrafficTypeDiagnostic: SA1PR15MB4919: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-FB-Source: Internal X-MS-Oob-TLC-OOBClassifiers: OLM:8882; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SN6PR1501MB2064.namprd15.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(376002)(136003)(366004)(346002)(396003)(39860400002)(53546011)(8676002)(2906002)(31686004)(186003)(66476007)(6916009)(2616005)(6486002)(66556008)(36756003)(478600001)(4326008)(86362001)(8936002)(316002)(54906003)(38100700002)(66946007)(52116002)(5660300002)(31696002)(83380400001)(45980500001)(43740500002);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?dlpoZzNmSHkxa1NyMENmT0J5YUszNmhDVXdGOC9RcDBpSGZDUkpmVWdvQlZD?= =?utf-8?B?NjhONG55UFZkVU5Uc3VVOG5iVStXQmZLUVBPRjlpaWYxeUtQRGxzZHdzWUxj?= =?utf-8?B?OE5iemZGUzg3YkZDenVxTnFXRGh4WDF0WE9GTTVxMGFjWFBxRmorNStVcC9W?= =?utf-8?B?TEJDL0FxNTN4K2tpNS9LblNGdmNqZFBqVXd5YmVuTHNtSklFaFlPVERrZFZJ?= =?utf-8?B?VFJyTlJ0ZVk4M296R0RFbWFJNmkzclJTU08yV0orczgyc0NjRkNHK2N6djhj?= =?utf-8?B?TEY1TUdObnRuUmhFbEh5TXJjbE1aWTdpZW14VUdRYy9TUUFQbmYyV1VJQXdE?= =?utf-8?B?K1NTRUdzRFlVRm1PT0N0cnQ3QzhXUklteWFaSWFkT0lHSlJyZURMSkhXQ1Vs?= =?utf-8?B?TTNweGorVS9hREZPRnNOcFpqQUF1U0p0NVZLV3hWK0IvVDc2d0FYQUxtb0Nv?= =?utf-8?B?NC83QUVUZVRIcWlNQWE5L0pEWkxvQzRMZFJwb05taS9EMkFPVFhsazlxRndU?= =?utf-8?B?VnZ5ZFRIM2FjUEhHNnlnamZOOVdRWExGQ0dJSEk2OGJRbnA1dU9uZUVRWlVh?= =?utf-8?B?QjJQSTJsVkV0Ync2YUVoR0xGQmlYRFk4MG9YRXFBa3FFOVE1RlRCWFlKeWpY?= =?utf-8?B?WVVVR2IyMjBNUzd2ZGNKWndmT1NqckNYS1MxYzhYM0wrODRvbE1HV2lZQ1hl?= =?utf-8?B?SnROcXZwWmZvZ09xandiT0loeHNQQnFOZ0FTZWxuMjNhVVEySEV1c0R1bWl6?= =?utf-8?B?TXlNcVlwc2toNEZlcmdmN01DaksvanB4clZNblRHeDI3ZGRtd1doZ0Q5L3c3?= =?utf-8?B?S0RzUTR2dnlkb3VvNmtNVjFnaWltV2Z2dnhWQ1RwNWhTcUdxVlVRZGVqdnB6?= =?utf-8?B?WENsMVBzNHdqQldlRGRkVnd0Y3pTZ2RZanI2MDNFRnRkNDkwUVg2VmVWVFlY?= =?utf-8?B?MDN1eDh4d09ZMitscjRkcGh6QS9PMklqV3AwcmsvNnRrQWlLcDdoVnZaSUVh?= =?utf-8?B?YXJyU2F4dlJseXdHYjVXVXMzUHpHdCs5NFNBQVhrMmliZWEvTjZXZXpTRS9v?= =?utf-8?B?UVZWYTRCTUtLdjRpUFpocWtvOWc5VGhrTjRCZEhUWlAyL2FCMmlHOVdLbzZ5?= =?utf-8?B?OFNPZkcxbUd5ZW55OFh2Zjh6QnZycU9Kc3BkMTFwMmRhVXdLZm5jdzJCYWR3?= =?utf-8?B?ZE1UMzRhU2dHUFdmWUp5U3JJVFo0S2hTQWZuWmNhU3lzdzdLVFhEUW1vZkpC?= =?utf-8?B?d21vNEFZc0hUV1ptMmtmOVUwTGJ2MXNxeUJSc2RYR08yangxcSt4UFQxL3Nk?= =?utf-8?B?eStVWGxQSVo5Nld5ZXBzM01taWhwczZQb1BGaTV6WlI1d1hPcG5MdTQ3dXpw?= =?utf-8?B?czVDbkpTTWtDV1lOMm1JWVFBSHpFVkRYcHgwM2dMS0JTUUtLSU43TTFXTzcx?= =?utf-8?B?ZHRmQkZHUkl2MFJrT084YnVMdmRDdmMwZ2hCUE9aWVVzRFl1NU9iRHYvclFF?= =?utf-8?B?ZXNzcUhieGxvZUMveVEyVEJyc1BONDkrSGV1OWpib2JtZTQ0RUJGc3V3cDZ3?= =?utf-8?B?MGJQOCtMUGlsbEFYWERUd09UcklrU1ZWbWh0aHBWNldZVG5KZnkzTmJOR0p1?= =?utf-8?B?cmFndGw1eE4zclBpVEUyZkJDaG5ZaG1WQTNTRzZ3QzBVU3RiNGFhTkR3THM1?= =?utf-8?B?S2xxOFBJVXV4S0xWTURQSy9xMWlEemlBZldnSWw2ZXNzcTN1UngvbElvWTZp?= =?utf-8?B?c29lR0ltcjJySkFwNWF4N3dYSVc1WWtCSXg0S1kwTXNYNUp3R2NLOHhJZGkx?= =?utf-8?Q?NWTfTrg4a+8jvvOMfWySKqAgGuvVsBhrBfYO4=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: 09beaa7d-9b9e-4dea-43c0-08d952a88801 X-MS-Exchange-CrossTenant-AuthSource: SN6PR1501MB2064.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Jul 2021 15:50:04.0442 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: qUDNiP2NFFbJVJFtsbC4k+hlu6e6MEE9Uf/froBtyUa1i5XaNNlyuZQTrz/DJTsd X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR15MB4919 X-OriginatorOrg: fb.com X-Proofpoint-ORIG-GUID: 7NZnxjSdaCkYLviK2SoXp1LqkQDT-pCs X-Proofpoint-GUID: 7NZnxjSdaCkYLviK2SoXp1LqkQDT-pCs X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-07-29_10:2021-07-29,2021-07-29 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 spamscore=0 impostorscore=0 priorityscore=1501 mlxscore=0 mlxlogscore=999 phishscore=0 clxscore=1015 adultscore=0 suspectscore=0 malwarescore=0 bulkscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2107290099 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 7/29/21 6:24 AM, Johan Almbladh wrote: > On Thu, Jul 29, 2021 at 2:55 AM Yonghong Song wrote: >>> +static int bpf_fill_long_jmp(struct bpf_test *self) >>> +{ >>> + unsigned int len = BPF_MAXINSNS; >> >> BPF_MAXINSNS is 4096 as defined in uapi/linux/bpf_common.h. >> Will it be able to trigger a PC relative branch + long >> conditional jump? > > It does, on the MIPS32 JIT. The ALU64 MUL instruction with a large > immediate was chosen since it expands to a lot of MIPS32 instructions: > 2 to load the immediate, 1 to zero/sign extend it, and then 9 for the > 64x64 multiply. Maybe added a comment in the code to mention that with BPF_MAXINSNS PC relative branch + long conditional jump can be triggered on MIPS32 JIT. Other architecture may need a different/larger number? > > Other JITs will be different of course. On the other hand, other > architectures have other limitations that this test may not trigger > anyway. I added the test because I was implementing a non-trivial > iterative branch conversion logic in the MIPS32 JIT. One can argue > that when such complex JIT mechanisms are added, the test suite should > also be updated to cover that, especially if the mechanism handles > something that almost never occur in practice. > > Since I was able to trigger the branch conversion with BPF_MAXINSNS > instructions, and no other test was using more, I left it at that. > However, should I or someone else work on the MIPS64 JIT, I think > updating the test suite so that similar special cases there are > triggered would be a valuable contribution. >