Received: by 2002:a25:ab43:0:0:0:0:0 with SMTP id u61csp4486595ybi; Mon, 3 Jun 2019 11:45:05 -0700 (PDT) X-Google-Smtp-Source: APXvYqxlqtIB5QfBXP7MZAhksSom8RZxZ3mDmmICyQfijxC+rmQMqmCEMy/ZbVm7m86Qs2VBGUeh X-Received: by 2002:a17:902:1125:: with SMTP id d34mr31574930pla.101.1559587505867; Mon, 03 Jun 2019 11:45:05 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1559587505; cv=none; d=google.com; s=arc-20160816; b=Qx9jynpnZtPAva0rCm3EdOhmxN7CtFppZq7o9LfdrjXJiEH0Wdoqeg3xJPOjogWfqX fSSOwjW68TVz8RITHVz9s1UB5cwwxVcK6hIGffHMsFp40XPaefpjpVhx5eOGkRVm2L2o spK8K36h0ABe8jj9Stf90dQi6qMj8HbJ/pIsDk2/bxsMZqjvSo9jBGLNB96ZYTMlZdO0 t02dtS+iszmPHkPhFUS5QTYq1iVT7sxoAoTFZlKPAsixA+P/BratdIkVaiKFsgcbyt/z XwfSk5ssYkOk9gpCsf19c83nj7Wa9DCdAdX3vQDK7t17wAZLHckHiGJoWx17x4BEy4Qi WByA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding :content-language:in-reply-to:mime-version:user-agent:date :message-id:autocrypt:openpgp:from:references:newsgroups:cc:to :subject:dkim-signature; bh=CHQdvmHpZ+nNkXgwTaRppfMOKNBm5bThrSa4Dlvw3O4=; b=M0k7QTt7pmScaOE1IBIhezmXmEjd8nvqj6xSB7N7AYZSipOnY3fQB67/LlWHIDMpfs 76dpk6MUFMxFS6ewYqPlfa+rdznYNTUF74fmDpvLZUHvrsesOj3xnEsTzzxiCKD11HKH RN0yf6SZax0x84nJ91kBWdOMJ5sBBdKEqTD+AWwCX3ODlW8nFvr82G82KvWBWnF0NDsT G3V8/C53jVj6BIQLoL4UYW/fdxLOwlOD87WMpaeXWlavf4TCxvjFl1YNt7vp5l9J9AnQ IqiLJEDTJ265maC8cAatAGiDNzKYeXqnEubHaYQAuPDPxmDU95G/o3eZAnZTsmSyJVnI A/1A== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@synopsys.com header.s=mail header.b=cPJC4bgb; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=synopsys.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id g23si20917938pfi.153.2019.06.03.11.44.49; Mon, 03 Jun 2019 11:45:05 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@synopsys.com header.s=mail header.b=cPJC4bgb; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=synopsys.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726636AbfFCSna (ORCPT + 99 others); Mon, 3 Jun 2019 14:43:30 -0400 Received: from smtprelay-out1.synopsys.com ([198.182.47.102]:42344 "EHLO smtprelay-out1.synopsys.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726055AbfFCSn3 (ORCPT ); Mon, 3 Jun 2019 14:43:29 -0400 Received: from mailhost.synopsys.com (dc8-mailhost1.synopsys.com [10.13.135.209]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by smtprelay-out1.synopsys.com (Postfix) with ESMTPS id CCF8FC1E03; Mon, 3 Jun 2019 18:43:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=synopsys.com; s=mail; t=1559587419; bh=CHQdvmHpZ+nNkXgwTaRppfMOKNBm5bThrSa4Dlvw3O4=; h=Subject:To:CC:References:From:Date:In-Reply-To:From; b=cPJC4bgbctAhHRufhBWEQXyiDzTNCOD1l1jtppO66BWIaTQN0sf6BCC3kZW8KN1O0 0P4YknM0CEwgY371CHazcYw76x7cGgQ9SxsHRdgM1c2byC1lJsoepTcvO/SkDWtJQ3 8ifCYP1JHYcimcmwXPn0JJq9wo9rSqrsMg7/ncFdRP+Huqmk6gkW41O6u19J8YLjjj UYBESk46oqCN40ZL62jb92maAyL1hiYwuZmSB4GL8NlH+FBVfAWqV6W6YZJGVh9zuk rCI6peCKbt7PHHPfGJIBlq9bZRMRO43koCpnKtkhbqSv3eK9CkAKq8npgP9BNA4CZK B38HfFTgkNE5Q== Received: from US01WXQAHTC1.internal.synopsys.com (us01wxqahtc1.internal.synopsys.com [10.12.238.230]) (using TLSv1.2 with cipher AES128-SHA256 (128/128 bits)) (No client certificate requested) by mailhost.synopsys.com (Postfix) with ESMTPS id 8E8FEA005D; Mon, 3 Jun 2019 18:43:28 +0000 (UTC) Received: from IN01WEHTCB.internal.synopsys.com (10.144.199.106) by US01WXQAHTC1.internal.synopsys.com (10.12.238.230) with Microsoft SMTP Server (TLS) id 14.3.408.0; Mon, 3 Jun 2019 11:43:28 -0700 Received: from IN01WEHTCA.internal.synopsys.com (10.144.199.103) by IN01WEHTCB.internal.synopsys.com (10.144.199.105) with Microsoft SMTP Server (TLS) id 14.3.408.0; Tue, 4 Jun 2019 00:13:25 +0530 Received: from [10.10.161.35] (10.10.161.35) by IN01WEHTCA.internal.synopsys.com (10.144.199.243) with Microsoft SMTP Server (TLS) id 14.3.408.0; Tue, 4 Jun 2019 00:13:37 +0530 Subject: Re: single copy atomicity for double load/stores on 32-bit systems To: Peter Zijlstra CC: Will Deacon , "Paul E. McKenney" , arcml , lkml , "linux-arch@vger.kernel.org" Newsgroups: gmane.linux.kernel,gmane.linux.kernel.arc,gmane.linux.kernel.cross-arch References: <2fd3a455-6267-5d21-c530-41964a4f6ce9@synopsys.com> <20190531082112.GH2623@hirez.programming.kicks-ass.net> From: Vineet Gupta Openpgp: preference=signencrypt Autocrypt: addr=vgupta@synopsys.com; keydata= mQINBFEffBMBEADIXSn0fEQcM8GPYFZyvBrY8456hGplRnLLFimPi/BBGFA24IR+B/Vh/EFk B5LAyKuPEEbR3WSVB1x7TovwEErPWKmhHFbyugdCKDv7qWVj7pOB+vqycTG3i16eixB69row lDkZ2RQyy1i/wOtHt8Kr69V9aMOIVIlBNjx5vNOjxfOLux3C0SRl1veA8sdkoSACY3McOqJ8 zR8q1mZDRHCfz+aNxgmVIVFN2JY29zBNOeCzNL1b6ndjU73whH/1hd9YMx2Sp149T8MBpkuQ cFYUPYm8Mn0dQ5PHAide+D3iKCHMupX0ux1Y6g7Ym9jhVtxq3OdUI5I5vsED7NgV9c8++baM 7j7ext5v0l8UeulHfj4LglTaJIvwbUrCGgtyS9haKlUHbmey/af1j0sTrGxZs1ky1cTX7yeF nSYs12GRiVZkh/Pf3nRLkjV+kH++ZtR1GZLqwamiYZhAHjo1Vzyl50JT9EuX07/XTyq/Bx6E dcJWr79ZphJ+mR2HrMdvZo3VSpXEgjROpYlD4GKUApFxW6RrZkvMzuR2bqi48FThXKhFXJBd JiTfiO8tpXaHg/yh/V9vNQqdu7KmZIuZ0EdeZHoXe+8lxoNyQPcPSj7LcmE6gONJR8ZqAzyk F5voeRIy005ZmJJ3VOH3Gw6Gz49LVy7Kz72yo1IPHZJNpSV5xwARAQABtCpWaW5lZXQgR3Vw dGEgKGFsaWFzKSA8dmd1cHRhQHN5bm9wc3lzLmNvbT6JAj4EEwECACgCGwMGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheABQJbBYpwBQkLx0HcAAoJEGnX8d3iisJeChAQAMR2UVbJyydOv3aV jmqP47gVFq4Qml1weP5z6czl1I8n37bIhdW0/lV2Zll+yU1YGpMgdDTHiDqnGWi4pJeu4+c5 xsI/VqkH6WWXpfruhDsbJ3IJQ46//jb79ogjm6VVeGlOOYxx/G/RUUXZ12+CMPQo7Bv+Jb+t NJnYXYMND2Dlr2TiRahFeeQo8uFbeEdJGDsSIbkOV0jzrYUAPeBwdN8N0eOB19KUgPqPAC4W HCg2LJ/o6/BImN7bhEFDFu7gTT0nqFVZNXlOw4UcGGpM3dq/qu8ZgRE0turY9SsjKsJYKvg4 djAaOh7H9NJK72JOjUhXY/sMBwW5vnNwFyXCB5t4ZcNxStoxrMtyf35synJVinFy6wCzH3eJ XYNfFsv4gjF3l9VYmGEJeI8JG/ljYQVjsQxcrU1lf8lfARuNkleUL8Y3rtxn6eZVtAlJE8q2 hBgu/RUj79BKnWEPFmxfKsaj8of+5wubTkP0I5tXh0akKZlVwQ3lbDdHxznejcVCwyjXBSny d0+qKIXX1eMh0/5sDYM06/B34rQyq9HZVVPRHdvsfwCU0s3G+5Fai02mK68okr8TECOzqZtG cuQmkAeegdY70Bpzfbwxo45WWQq8dSRURA7KDeY5LutMphQPIP2syqgIaiEatHgwetyVCOt6 tf3ClCidHNaGky9KcNSQ Message-ID: <77b30ed2-3211-222b-1342-051a6cde4f77@synopsys.com> Date: Mon, 3 Jun 2019 11:43:20 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190531082112.GH2623@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.10.161.35] Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/31/19 1:21 AM, Peter Zijlstra wrote: > And I'll stand by my earlier conviction that any architecture that has a > native u64 (be it a 64bit arch or a 32bit with double-width > instructions) but has an ABI that allows u32 alignment on them is daft. Why ? For 64-bit data on 32-bit systems, hardware doesn't claim to provide any single-copy atomicity for such data and software doesn't expect either.