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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 DC4A9C388F9 for ; Tue, 17 Nov 2020 02:15:57 +0000 (UTC) Received: from shelob.surriel.com (shelob.surriel.com [96.67.55.147]) (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 4F23E24699 for ; Tue, 17 Nov 2020 02:15:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=vt-edu.20150623.gappssmtp.com header.i=@vt-edu.20150623.gappssmtp.com header.b="EA0pdsai" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4F23E24699 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=vt.edu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernelnewbies-bounces@kernelnewbies.org Received: from localhost ([::1] helo=shelob.surriel.com) by shelob.surriel.com with esmtp (Exim 4.94) (envelope-from ) id 1keqWt-00081I-J8; Mon, 16 Nov 2020 21:15:35 -0500 Received: from mail-qk1-x729.google.com ([2607:f8b0:4864:20::729]) by shelob.surriel.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1keqWr-00081D-8X for kernelnewbies@kernelnewbies.org; Mon, 16 Nov 2020 21:15:33 -0500 Received: by mail-qk1-x729.google.com with SMTP id l2so19137940qkf.0 for ; Mon, 16 Nov 2020 18:15:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=vt-edu.20150623.gappssmtp.com; s=20150623; h=sender:from:to:cc:subject:in-reply-to:references:mime-version :content-transfer-encoding:date:message-id; bh=ESuu3NgjhRIzkOcaqiY0VoAH0TV/Tj+63vQvrbD9Kg8=; b=EA0pdsaigL70mgf4GADKGaUi+5YN+kxUp2swSzDP3V49HxqQMjT7fQjs/TyMxtZYSU piE41NoqDzcSgC9iOjCT/KSi/0ok2c88g7Fkl7CVhHTyyZsUGlDBFXdxNroKXHyEmhIL 3EcEtVBnQHEDrg+QdJUOAQO/DUpMIdPqRCRMeQjhS+t8ykVtrVMUWPqskqD38WMqUhe/ M9qQLcD3OfnCY5sYvMqIIwoeFjY3Yi4R5qknkeLHgU7jTXwUkuHijrWHmfgP3W/DYwzq l7b5MKv5WRDJLayRl/n8h9KxPXKzJ3ihX0ZVnSsZstM4eA+uOx5YI1c7oHzVpb+1aW0Y C5nA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:in-reply-to:references :mime-version:content-transfer-encoding:date:message-id; bh=ESuu3NgjhRIzkOcaqiY0VoAH0TV/Tj+63vQvrbD9Kg8=; b=A5LvLboX8OzT4/NqAmJA/Jiwtogk9GjbypNUpuj1m31726o4Mf0DqAbB7eCiF/Z/LG IO3ePwIYI3mHOhZQO8Lw7tbdd84aHiFJDhNMc22tfmnM+cRi04BbU14qjym2oJ36ZdVz A95Gjx665Mn0c09K/gTVN+MG3nNMGyk7cHiVuNIT8KfdRd22MMNLTNSwY9/dJQTEG3TE lvFnx2kfc/q1k2R+oXet5hmhIoetnaBTTRGocgfPzGNBhJKkM4bOpTTnnQsZkxOGukDS jmR1UOx3kh/g/6Es3Df2/K9ymcp2L6sz+JFDtTnlGJQXsKOL72kyZ40WcO52mnKe7sDZ wRWQ== X-Gm-Message-State: AOAM533rMfM8b3zkWLveYspHckhn31u/qGCGHXEo14pk8KHEZJ7O3qtt Qb9wWJO3Wi4XrLJP9C4z5CtIdQ== X-Google-Smtp-Source: ABdhPJzPAzmmblAAz5zREy9GWVR8ltEyeeuQaC8rPwJXrZCi+x4CLvB7PaahDvJaYQGZppWLit7BOw== X-Received: by 2002:a37:793:: with SMTP id 141mr17241448qkh.462.1605579270895; Mon, 16 Nov 2020 18:14:30 -0800 (PST) Received: from turing-police ([2601:5c0:c380:d61::359]) by smtp.gmail.com with ESMTPSA id p8sm13699257qtc.37.2020.11.16.18.14.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Nov 2020 18:14:29 -0800 (PST) From: "Valdis Kl=?utf-8?Q?=c4=93?=tnieks" X-Google-Original-From: "Valdis Kl=?utf-8?Q?=c4=93?=tnieks" X-Mailer: exmh version 2.9.0 11/07/2018 with nmh-1.7+dev To: Wonhyuk Yang Subject: Re: arm64: Question about barriers with the mmu off In-Reply-To: References: Mime-Version: 1.0 Date: Mon, 16 Nov 2020 21:14:28 -0500 Message-ID: <213088.1605579268@turing-police> Cc: kernelnewbies X-BeenThere: kernelnewbies@kernelnewbies.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Learn about the Linux kernel List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============6866537894438844223==" Errors-To: kernelnewbies-bounces@kernelnewbies.org --===============6866537894438844223== Content-Type: multipart/signed; boundary="==_Exmh_1605579268_118566P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit --==_Exmh_1605579268_118566P Content-Type: text/plain; charset=us-ascii On Mon, 16 Nov 2020 20:58:52 +0900, Wonhyuk Yang said: > str w0, [x1] So we dirtied the cache line. > dmb sys > dc ivac, x1 // Invalidate potentially stale cache line So we invalidate it. > Is there any problem, if the dc operation precedes the store operation? If you swap them, you get... dc ivac,x1 // invalidate a cache line that's probably OK str w0,[x1 // and now we do a store that leaves a possibly stale cache line In other words, if you swap them you may leave an un-invalidated stale cache line. --==_Exmh_1605579268_118566P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Comment: Exmh version 2.9.0 11/07/2018 iQIVAwUBX7MyBAdmEQWDXROgAQIm+Q//X5HITc2cacSW1RSrZjyxrRkAM4gDtMjs eq8QHnrvdj5ZsDNL7hgtTTFBGSWx3bmPlzvObnM2NGGbe7k6+jooOchZEAIIYT+e QT/aLEqDO5EAirHaXNrS3qpkxApAzgEcgZD/+ZnHvfc4DiR/a4MyZM5NqIlJ9o/b 7qzEcSdVn/D4Mk0Nz6ql/F7rMwwE0RY1PxaQ9ai4l6utaYG5B7TEQ32U6ZPb949D Slbglv9uXM2M/5u2QHwWIW0ZRyLjPhKc92J2cuBBb6h0w3+C3iMgYqZg5HGdzMVs WSMCyKGmPNBkN2g+ERrGP+I3XFR+nGSmwjwSZSM8zz7UjqM/RCpGYQ50lCums28N 2B1GLnv17ei+RpdTP9m2pDoweybCQcGQpJXZPG0Tl8pro5sVE95FcbO7gTTexPeM SchTvSyZbHY5+wfVOcstlfD9sCrBPjHd7OqURjxlTdCdP4a6yfU4ztde37yPtm00 +dXCYAzZnkljBEBOA0xvfqlHDeW3kwoe1XS4VDDzA9ktq+tfeI5rxXg/geGdiR4n 4FKFbFsDaJvNQrqQXrH27uyyEaPpxxxy6szcOHPbndNAti5I0SIE+nR8MEoUL7Nc JVRyxdVab+uxf15LS3NFcFwzvgslDb+DrIGT8pl+RjA8P2y/061X/BZHjnYCC53S FNs3+H7HHlY= =xYt1 -----END PGP SIGNATURE----- --==_Exmh_1605579268_118566P-- --===============6866537894438844223== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies --===============6866537894438844223==--