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=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 A644EC433DF for ; Wed, 29 Jul 2020 08:36:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 909FB2076E for ; Wed, 29 Jul 2020 08:36:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727994AbgG2Igk (ORCPT ); Wed, 29 Jul 2020 04:36:40 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([185.58.86.151]:51444 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727816AbgG2Igi (ORCPT ); Wed, 29 Jul 2020 04:36:38 -0400 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-43-2zI0R3XJNsWV7u6ffLfy4w-1; Wed, 29 Jul 2020 09:36:34 +0100 X-MC-Unique: 2zI0R3XJNsWV7u6ffLfy4w-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Wed, 29 Jul 2020 09:36:33 +0100 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Wed, 29 Jul 2020 09:36:33 +0100 From: David Laight To: "'Madhavan T. Venkataraman'" , "Andy Lutomirski" CC: "kernel-hardening@lists.openwall.com" , "linux-api@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-fsdevel@vger.kernel.org" , "linux-integrity@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "oleg@redhat.com" , "x86@kernel.org" Subject: RE: [PATCH v1 0/4] [RFC] Implement Trampoline File Descriptor Thread-Topic: [PATCH v1 0/4] [RFC] Implement Trampoline File Descriptor Thread-Index: AQHWZOCQT+e4gDrzGEmP/30MMvDTCqkdFOrwgABBt1CAAORUsA== Date: Wed, 29 Jul 2020 08:36:33 +0000 Message-ID: References: <20200728131050.24443-1-madvenka@linux.microsoft.com> <59246260-e535-a9f1-d89e-4e953288b977@linux.microsoft.com> In-Reply-To: <59246260-e535-a9f1-d89e-4e953288b977@linux.microsoft.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; 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Wed, 29 Jul 2020 09:36:33 +0100 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Wed, 29 Jul 2020 09:36:33 +0100 From: David Laight To: "'Madhavan T. Venkataraman'" , "Andy Lutomirski" Subject: RE: [PATCH v1 0/4] [RFC] Implement Trampoline File Descriptor Thread-Topic: [PATCH v1 0/4] [RFC] Implement Trampoline File Descriptor Thread-Index: AQHWZOCQT+e4gDrzGEmP/30MMvDTCqkdFOrwgABBt1CAAORUsA== Date: Wed, 29 Jul 2020 08:36:33 +0000 Message-ID: References: <20200728131050.24443-1-madvenka@linux.microsoft.com> <59246260-e535-a9f1-d89e-4e953288b977@linux.microsoft.com> In-Reply-To: <59246260-e535-a9f1-d89e-4e953288b977@linux.microsoft.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200729_043639_463399_0CD1510A X-CRM114-Status: UNSURE ( 9.96 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "kernel-hardening@lists.openwall.com" , "linux-api@vger.kernel.org" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "oleg@redhat.com" , "linux-security-module@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-integrity@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Madhavan T. Venkataraman > Sent: 28 July 2020 19:52 ... > trampfd faults are instruction faults that go through a different code path than > the one that calls handle_mm_fault(). Perhaps, it is the handle_mm_fault() that > is time consuming. Could you clarify? Given that the expectation is a few instructions in userspace (eg to pick up the original arguments for a nested call) the (probable) thousands of clocks taken by entering the kernel (especially with page table separation) is a massive delta. If entering the kernel were cheap no one would have added the DSO functions for getting the time of day. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel 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=-4.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 65D24C433DF for ; Wed, 29 Jul 2020 08:36:57 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id C068B20838 for ; Wed, 29 Jul 2020 08:36:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C068B20838 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=ACULAB.COM Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-19487-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 20400 invoked by uid 550); 29 Jul 2020 08:36:49 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 20380 invoked from network); 29 Jul 2020 08:36:48 -0000 X-MC-Unique: 2zI0R3XJNsWV7u6ffLfy4w-1 From: David Laight To: "'Madhavan T. Venkataraman'" , "Andy Lutomirski" CC: "kernel-hardening@lists.openwall.com" , "linux-api@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-fsdevel@vger.kernel.org" , "linux-integrity@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "oleg@redhat.com" , "x86@kernel.org" Subject: RE: [PATCH v1 0/4] [RFC] Implement Trampoline File Descriptor Thread-Topic: [PATCH v1 0/4] [RFC] Implement Trampoline File Descriptor Thread-Index: AQHWZOCQT+e4gDrzGEmP/30MMvDTCqkdFOrwgABBt1CAAORUsA== Date: Wed, 29 Jul 2020 08:36:33 +0000 Message-ID: References: <20200728131050.24443-1-madvenka@linux.microsoft.com> <59246260-e535-a9f1-d89e-4e953288b977@linux.microsoft.com> In-Reply-To: <59246260-e535-a9f1-d89e-4e953288b977@linux.microsoft.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: base64 RnJvbTogTWFkaGF2YW4gVC4gVmVua2F0YXJhbWFuDQo+IFNlbnQ6IDI4IEp1bHkgMjAyMCAxOTo1 Mg0KLi4uDQo+IHRyYW1wZmQgZmF1bHRzIGFyZSBpbnN0cnVjdGlvbiBmYXVsdHMgdGhhdCBnbyB0 aHJvdWdoIGEgZGlmZmVyZW50IGNvZGUgcGF0aCB0aGFuDQo+IHRoZSBvbmUgdGhhdCBjYWxscyBo YW5kbGVfbW1fZmF1bHQoKS4gUGVyaGFwcywgaXQgaXMgdGhlIGhhbmRsZV9tbV9mYXVsdCgpIHRo YXQNCj4gaXMgdGltZSBjb25zdW1pbmcuIENvdWxkIHlvdSBjbGFyaWZ5Pw0KDQpHaXZlbiB0aGF0 IHRoZSBleHBlY3RhdGlvbiBpcyBhIGZldyBpbnN0cnVjdGlvbnMgaW4gdXNlcnNwYWNlDQooZWcg dG8gcGljayB1cCB0aGUgb3JpZ2luYWwgYXJndW1lbnRzIGZvciBhIG5lc3RlZCBjYWxsKQ0KdGhl IChwcm9iYWJsZSkgdGhvdXNhbmRzIG9mIGNsb2NrcyB0YWtlbiBieSBlbnRlcmluZyB0aGUNCmtl cm5lbCAoZXNwZWNpYWxseSB3aXRoIHBhZ2UgdGFibGUgc2VwYXJhdGlvbikgaXMgYSBtYXNzaXZl DQpkZWx0YS4NCg0KSWYgZW50ZXJpbmcgdGhlIGtlcm5lbCB3ZXJlIGNoZWFwIG5vIG9uZSB3b3Vs ZCBoYXZlIGFkZGVkDQp0aGUgRFNPIGZ1bmN0aW9ucyBmb3IgZ2V0dGluZyB0aGUgdGltZSBvZiBk YXkuDQoNCglEYXZpZA0KDQotDQpSZWdpc3RlcmVkIEFkZHJlc3MgTGFrZXNpZGUsIEJyYW1sZXkg Um9hZCwgTW91bnQgRmFybSwgTWlsdG9uIEtleW5lcywgTUsxIDFQVCwgVUsNClJlZ2lzdHJhdGlv biBObzogMTM5NzM4NiAoV2FsZXMpDQo=