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=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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=no 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 65FD1C4708F for ; Wed, 2 Jun 2021 11:54:17 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3082F61246 for ; Wed, 2 Jun 2021 11:54:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3082F61246 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=windriver.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:In-Reply-To:Date:Message-ID:From: References:Cc:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=WvsJ3CNx/FU8alwyksx4eAV9VC+ct1LnEGxa/g2xI+0=; b=TP3WxCs4CBWpcGnmOL/RqrKETH Z/1Li1/Qq+Ofob1lOSuppn/t9IcvwHq/gukMkZmewrJNF7WLQ37RfPhOAo2JadR/4rOGkNYGhn7ky Z/xRuk71sQXe/p8hDb45s3RlihG4cG63CAotav6DXttRgrrSFb/6ZU2ceejblb+b2DaGoznxGTp9J n4CNE59zxjmlX/GqoUvUA0uu3KNX/IElkDIh+Ah+anGGu/g3zdHHQgUWjioQIDXKYi0qN590RswGP bXY1dCO6ygeX+Qbg+rb2rpoBICYlwjo9TY/v8nICcfTxtzqwSo0L72g3NunYPYG2UHcrHUnF8Dr0A 2CXe5I3g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1loPOk-003pr5-DZ; Wed, 02 Jun 2021 11:51:00 +0000 Received: from mx0a-0064b401.pphosted.com ([205.220.166.238]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1loP1c-003jbw-7p for linux-arm-kernel@lists.infradead.org; Wed, 02 Jun 2021 11:27:09 +0000 Received: from pps.filterd (m0250810.ppops.net [127.0.0.1]) by mx0a-0064b401.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 152BKevg011143; Wed, 2 Jun 2021 04:26:16 -0700 Received: from nam04-mw2-obe.outbound.protection.outlook.com (mail-mw2nam08lp2175.outbound.protection.outlook.com [104.47.73.175]) by mx0a-0064b401.pphosted.com with ESMTP id 38ww8v8byp-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 02 Jun 2021 04:26:16 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=X6KIgxwj2M9/FXhCK7EJonlZF1WFafcHWRIUfzklpSgw/vSHSwphXWO8Zame4CnMN207XG/0u7Aj83w7XDasU8OMKFZ7ZUOBkojQK4zMlg34XjUUFW9FZbqTq2E6Ov7FnrzP+e75eOuW+dwqHmpLyC+AzqtLt+0lIkcyQQY+UnAdr4gfcOn1Tj3lH/6TfGMmdLVg5hkxbrIEpI9sBchuO0l/UKOqyBaCQ2bA8MUAS58JaPXySjvXQMOL3qS7szHB9uIDpC9kBnz05n5uj7okv8SUqK2p58HIcQqxoOOxIOo69hCKSE5saEYDoia+xIzxqGhNi8yfnslgImR0rx5YFg== 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=UQ4To3v4UW0NyhcVR+1mvWNqXPVPvwx0m4AhbmB+GUE=; b=k+fSzqSu9KyCPgehrm1EzlcCb7Y2Io8Rzbyd+0iTVJeHvtRQF9Pjaf2vFvhRpvbDDNcZFSf60xGxi8yzxPY8/ODPhhzSvbc4pkPxMW9Jc5sSr7uhmIjEeyewFB36whQNvUqn17l9mJfXv94D4DvTi230h5FEjPvnJ+TI+AUTFo7i8U3oik5pFLRf1uiXNK89oJeuANivTy3Ff1Ol3SkhuilRYZYU7AF4RmWRg+HQSe8aZ2B/BYnFLGz/5KC2w9hW5aywR8QLmDLCO1CWvIMa6O4PvuoUQM6culEs6wCXcMKUamZZv57ep7uyr+JA0GDZHw+JGhFryCzP5mQur18nKg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=windriver.com; dmarc=pass action=none header.from=windriver.com; dkim=pass header.d=windriver.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=windriversystems.onmicrosoft.com; s=selector2-windriversystems-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=UQ4To3v4UW0NyhcVR+1mvWNqXPVPvwx0m4AhbmB+GUE=; b=RnnPVw4OXI/TfPUk1pOrkTgTrMK4MF5cA+8XK8rUv2rXnz3Xr2jrFjyisTfjqN5EEx/gkRSIIae9GPeaAvYGJWEwryxgxN3K+lYPbm8vCfQq1UHuTilu3wVVpmfnIPcA5WigPPdRXtr9y0x7IfU+5br9aWrVkSgGnjUexVjpbPQ= Authentication-Results: vger.kernel.org; dkim=none (message not signed) header.d=none;vger.kernel.org; dmarc=none action=none header.from=windriver.com; Received: from BY5PR11MB4241.namprd11.prod.outlook.com (2603:10b6:a03:1ca::13) by BY5PR11MB4103.namprd11.prod.outlook.com (2603:10b6:a03:18c::29) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4195.21; Wed, 2 Jun 2021 11:26:13 +0000 Received: from BY5PR11MB4241.namprd11.prod.outlook.com ([fe80::34b3:17c2:b1ad:286c]) by BY5PR11MB4241.namprd11.prod.outlook.com ([fe80::34b3:17c2:b1ad:286c%5]) with mapi id 15.20.4173.030; Wed, 2 Jun 2021 11:26:13 +0000 Subject: Re: [PATCH 1/1] bpf: avoid unnecessary IPI in bpf_flush_icache To: Will Deacon , Daniel Borkmann Cc: ast@kernel.org, zlim.lnx@gmail.com, catalin.marinas@arm.com, andrii@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20210601150625.37419-1-yanfei.xu@windriver.com> <20210601150625.37419-2-yanfei.xu@windriver.com> <56cc1e25-25c3-a3da-64e3-8a1c539d685b@iogearbox.net> <20210601174114.GA29130@willie-the-truck> From: "Xu, Yanfei" Message-ID: <7637dcdf-12b4-2861-3c76-f8a8e240a05e@windriver.com> Date: Wed, 2 Jun 2021 19:26:03 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 In-Reply-To: <20210601174114.GA29130@willie-the-truck> Content-Language: en-US X-Originating-IP: [60.247.85.82] X-ClientProxiedBy: HK0PR01CA0056.apcprd01.prod.exchangelabs.com (2603:1096:203:a6::20) To BY5PR11MB4241.namprd11.prod.outlook.com (2603:10b6:a03:1ca::13) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [128.224.162.160] (60.247.85.82) by HK0PR01CA0056.apcprd01.prod.exchangelabs.com (2603:1096:203:a6::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4173.20 via Frontend Transport; Wed, 2 Jun 2021 11:26:10 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: ffc924ff-b4c4-44d6-7d8b-08d925b93abc X-MS-TrafficTypeDiagnostic: BY5PR11MB4103: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:3968; X-MS-Exchange-SenderADCheck: 1 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:BY5PR11MB4241.namprd11.prod.outlook.com; PTR:; CAT:NONE; SFS:(4636009)(376002)(396003)(136003)(366004)(39850400004)(346002)(38100700002)(31696002)(38350700002)(4744005)(2906002)(66556008)(66476007)(31686004)(6706004)(6486002)(186003)(86362001)(36756003)(7416002)(16526019)(16576012)(6666004)(4326008)(8676002)(110136005)(5660300002)(8936002)(52116002)(956004)(2616005)(26005)(66946007)(478600001)(316002)(53546011)(78286007)(43740500002); DIR:OUT; SFP:1101; X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?K1NIZm40d09LREMvVkJRYjFaMXZwdGVnenNGVnlETDhEa0VhUTArQ05MTTNv?= =?utf-8?B?SEswUkNRa01nWHBHblgyTmlNdk1GRWtyQzhMTkx1TTNMdHhKclhUeEZ0Njlq?= =?utf-8?B?cEx4a3NxbTh2SEtMWnVSSld6UThvL2NMaWUzYVpKZTdUNnd5cmFzVjF1L3dM?= =?utf-8?B?U2t3NDlybWwrTjF2aDgzQzduVEEwN2thWXpTUzAvNlFPVjJsWXJTVTE2TjU5?= =?utf-8?B?bTc0T0pSek0wRE5DQnlPQ1dJOVF3SWQvT0szekRUQ2krK2wySnRaaTMvcFVM?= =?utf-8?B?dHBXbjRIOXhHTHlGUzFMMkYrcXJGYVJ6OEhRUFdmUGpWRjZOWUtaUEkySUZD?= =?utf-8?B?bFBVeHZXMmFvRkhGVk94VFdEMSt5SkRDRzdMMUpxZEtXNnZCaENSM3NWbWs4?= =?utf-8?B?ZzF0RDcrZ3N6YURwN09YVXBYM2l2dXpod3JGeGoxTjVMK2lKTEVWUHhoTGFQ?= =?utf-8?B?LzdxeVN3b2g1UjE0WGl2K2xmNzRObTZQYVpuSG1OcWJMZnNqb0NHUHh6a0Zl?= =?utf-8?B?azh2V24xd1ArQktnNkJlNlF5NG93bVVOZDV2R09YbXFsdktKYlBYL3hGdWVa?= =?utf-8?B?RTVQWVpmcVErcnhhckY5UVdMaldGSkt2RUNQNmM3ZWFmS2dtZXMzYVg0YzdT?= =?utf-8?B?Tm9Da1JsTE9Kc1d3VkU3Uk1BMEwybkVMSFQ2RkZmZTRKUTFOY0FMZU5HTTJX?= =?utf-8?B?NjNSSml5SGJvQSt2ckdDTFFFMXhKTk95TVkwa3prQlBGK2FoU2d5WEFiUDJw?= =?utf-8?B?eVBNWHpzbVVQbHhVN0ZWTDNaL2g2alZSQzZGWE5TdTJkYS9jbG5lN20wMUtV?= =?utf-8?B?OXNsUFVlSkg4WW1ENWhNcHBDc3RCTHpqUGNlWko4cVYrcEdLcGJFTXJRd1dT?= =?utf-8?B?RzdXalBkZU9CdVNYSGhHcFBkYWhBRDk2MTZCc3VHOWNvcm5CK3JGcFhJTkkw?= =?utf-8?B?VlMvSFZYUUV1aUJBam9YVWV2V2NsWXhiVllaZEgxSkxTUzRGdWZUeGwrYW9p?= =?utf-8?B?OU1pUEtpN1pmQzJJRVVXWWJma3VkdnVzdDVKemFMTHpjUmp2Q0FSNmJpdEo2?= =?utf-8?B?bWQwN3kxbGJYTzluR3Z5Q3c0cXJHWnRja2NndUt1VFU2aGc2ZDhsTXUrVXd3?= =?utf-8?B?d0djREtSaW5nZUh3TDhtS0QrMFpLWjZ4b2FFRS82a2NEek5jVlZ3MGROUlBQ?= =?utf-8?B?MWgreDlFbWVJK0JrU1dvaVU5M1gybmxFTmlZekhPemtSZlRWNzNCbVN0U1JZ?= =?utf-8?B?ZGxLd2l4bk5mK0pxRUxtalhkdnhBMmJ6emFIRFRGZ1FUY2p6ZDY3RXdSZk5y?= =?utf-8?B?OG1ya0swVnBhTnRReWZLanJRV1BBSHlYWE80ZUNiVFdRNmFaZU5KQi8yMkZ5?= =?utf-8?B?QVJnTzVqNTh4NVVpRzIxSGhTU29qei90M2N4SmZEMlRRYWFzSG1WMU9mUWhR?= =?utf-8?B?NjdkWjdBWGYvcmpVTWl2QXcwbVFvakRsR0ZuWnNrK1RRSTRDQS85QnpPYnhI?= =?utf-8?B?ajc3cTVYQ0xPUFBlRG4rL1RnNW1qdFJ5VG5CbStBMUkyWER5ODR5UmJlOWdZ?= =?utf-8?B?QWR3TVE2RkRyclRHN0owM1BFOHB4R2pBanJnd3dmMTBqLyt3NDN5N1lXb3lS?= =?utf-8?B?c3NBY3NONXFlK3o0dXE4QU03M001d1VYd3VzVXpsNlRvT1NVeTN6cFl5UXdy?= =?utf-8?B?amRrYjNGamFkMjhTaFR4R2Y3MENwZlV5Zy9aZHJHbks3dm1YVG5WZnpaUzZH?= =?utf-8?Q?bpNROBdbhEayxfdmhql4ondWv3K9Dl8brlaDhUR?= X-OriginatorOrg: windriver.com X-MS-Exchange-CrossTenant-Network-Message-Id: ffc924ff-b4c4-44d6-7d8b-08d925b93abc X-MS-Exchange-CrossTenant-AuthSource: BY5PR11MB4241.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Jun 2021 11:26:13.6583 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ddb2873-a1ad-4a18-ae4e-4644631433be X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: h7fUqaWXuarIqbXy6C3iiMBjCtx/No015pJOhx3oArfGQ67hmkfQ1+cDV7ltmA7PCTmLWUCfXmBO0Inwh7bnhg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR11MB4103 X-Proofpoint-GUID: URAxstFfMxT3UrD2nhLmQdkXXofw8kHy X-Proofpoint-ORIG-GUID: URAxstFfMxT3UrD2nhLmQdkXXofw8kHy X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.761 definitions=2021-06-02_06:2021-06-02, 2021-06-02 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 mlxscore=0 malwarescore=0 phishscore=0 mlxlogscore=999 bulkscore=0 lowpriorityscore=0 spamscore=0 impostorscore=0 adultscore=0 priorityscore=1501 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106020072 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210602_042704_421577_608661D2 X-CRM114-Status: GOOD ( 19.52 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 6/2/21 1:41 AM, Will Deacon wrote: > [Please note: This e-mail is from an EXTERNAL e-mail address] > > On Tue, Jun 01, 2021 at 07:20:04PM +0200, Daniel Borkmann wrote: >> On 6/1/21 5:06 PM, Yanfei Xu wrote: >>> It's no need to trigger IPI for keeping pipeline fresh in bpf case. >> >> This needs a more concrete explanation/analysis on "why it is safe" to do so >> rather than just saying that it is not needed. > > Agreed. You need to show how the executing thread ends up going through a > context synchronizing operation before jumping to the generated code if > the IPI here is removed. This patch came out with I looked through ftrace codes. Ftrace modify the text code and don't send IPI in aarch64_insn_patch_text_nosync(). I mistakenly thought the bpf is same with ftrace. But now I'm still not sure why the ftrace don't need the IPI to go through context synchronizing, maybe the worst situation is omit a tracing event? Thanks, Yanfei > > Will > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel