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 80FE9C2D0E4 for ; Tue, 17 Nov 2020 06:27:26 +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 C2056223AB for ; Tue, 17 Nov 2020 06:27:24 +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="Hj3N5jh3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C2056223AB 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 1keuSD-0002es-QY; Tue, 17 Nov 2020 01:27:01 -0500 Received: from mail-io1-xd2a.google.com ([2607:f8b0:4864:20::d2a]) by shelob.surriel.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1keuSB-0002eQ-JA for kernelnewbies@kernelnewbies.org; Tue, 17 Nov 2020 01:26:59 -0500 Received: by mail-io1-xd2a.google.com with SMTP id o11so20010905ioo.11 for ; Mon, 16 Nov 2020 22:26:58 -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=2uWgmIXB1nMHa/tmD3VHZ1VlPiFxpey2f/6i7JLOWGg=; b=Hj3N5jh3epmRmgqncCkDFWTqZvEFt78Q4aYJqdTzD6hyDf60OVtXwLCm3H0hK5VFl+ eR/V+wBy9pT0s0kEZseLVqjuvxpjdf4BvWD0Thbw1QXUb2uvMRtwzNhXvMCXgc4QDh/5 ItrXZ48vsIXFfqcZGuYScH02wQKzffg7/ZcST98NHyQZH90o0HiskQFoa3oAy/HtvAYx HWs30gXExaeQT+xZFq7BHgp/VDoEAG3YdChdHBdbf1iZTUZ7GaiLXmOXieUFVzW0A3go wEnT+YOpj8EXT3I9Q6i2clXHaSHP+Zm+QzRaFZu+Lq/sQMTVW2FrVtCfLREu6GqvBF+S 71mA== 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=2uWgmIXB1nMHa/tmD3VHZ1VlPiFxpey2f/6i7JLOWGg=; b=K48IxdGPBw8OFU6r7bIRew9LBwJ2ZXjI84rNJU2OdJileccOY0zGuLp5pJsnINtnvl +GSVHT5XWIHhRKgw4Q8tHAoGlcxCAdTUmJXtl5zkx0n2V6SaHxsIrMDnfIfOJUzGJgj/ ofYzxB7NtMCdpRl60wZnbELVBuHaPLRrku/ryFj0ONUFIqlMvExdwyHesHENvCC9XQ8K DOccmObMmI9VE3L6jS2H32o+Zd94Vd9h4MshzLuPyk1GYB5+fkPAF45JuqhpO0z+Nzbl 20sdpdlLpsoJqjmQxGbDFAwsWUz6fYK7gYGrSq1SWG50J6MkW0F/ElHYbp41nVzFvxu0 4oZw== X-Gm-Message-State: AOAM533JIJno7FpmhJUn+KJhFlZeLSsnr4I6dUVywJxTBoq0fc4Mjdbm R+QnX7HIjNUv5Henh/95Mdheeg== X-Google-Smtp-Source: ABdhPJw9q3QtmhBkQ+1bkCE0s58zZnBP/zsic1xim2xf8GpX+X+YkSV4MOSrrJJsbrBDUiVVtea4SA== X-Received: by 2002:a6b:911:: with SMTP id t17mr10435198ioi.197.1605594357834; Mon, 16 Nov 2020 22:25:57 -0800 (PST) Received: from turing-police ([2601:5c0:c380:d61::359]) by smtp.gmail.com with ESMTPSA id s16sm5835497ilp.43.2020.11.16.22.25.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Nov 2020 22:25:56 -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: <213088.1605579268@turing-police> <218162.1605584721@turing-police> Mime-Version: 1.0 Date: Tue, 17 Nov 2020 01:25:55 -0500 Message-ID: <227506.1605594355@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="===============2397150881855154641==" Errors-To: kernelnewbies-bounces@kernelnewbies.org --===============2397150881855154641== Content-Type: multipart/signed; boundary="==_Exmh_1605594354_118566P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit --==_Exmh_1605594354_118566P Content-Type: text/plain; charset=us-ascii On Tue, 17 Nov 2020 14:08:02 +0900, Wonhyuk Yang said: > > > > 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 > Could you explain me why the store still leaves stale cache? > We invalidated the cacheline and store will not make footprint in the cache. There's a race condition... Invalidate the cache line.... then another CPU manages to fetch the cache line. and then we do a store that doesn't update the cache - and the other CPU is still looking at the old data. --==_Exmh_1605594354_118566P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Comment: Exmh version 2.9.0 11/07/2018 iQIVAwUBX7Ns8gdmEQWDXROgAQJaBxAArLhjcSRXEUpm7muTK5PNjyhvg8UIq6s9 i5DLXpJDBJyOoXaMa1/U3ukxfoHY98rR3tC+Syc7Sl4km6e80zOzNx+f7unflfeG Ml8FG2jmzH2r1QhfCFhe74inAj8O/x4x3p/MFJVnV3/f033ntaKSPLQNYMwrrkIT IZ7lxUdTskGkjkRqXEmmUj1aoO6qQJTdZ9KCFRczeOqC2NM5/EDyAogBSz4Unfvp Js5bcFRWotfRaV8k1mQx0Wu4eqMDVSmiQPPM+kZ+QyvIYli3hqE4JBlT6pVDwBbt CYS2U5wcaW5IzTxZCesCbYa9HyZE/8pMdU2I6BeM57PVtADNxgs8iF4tPcXxbMNB eilCjsZVZD9Nmq/sI8Y08nPgRFvsGssXagHngeYfMu/gmddJKdbJrfEwjK0dULwu eu3hdOyjpXIKMgP5x2h4Hn6rDG7444krpR+ah0kwlucjEqIXe38I0l13uRB0YIaI fJ3RBtnMm4fW7N09CKaS+oH/89vuTMQocDYLN/7erbXnO8gUv7SwRbCiA993EXlT Px2d8iPVSwNxD14jjZ8N81Lijp8/PJrhejd/6U646R1KhWtAgs67un+qnCCZ5rT/ 7lOZd1RoTRG1SQN1lniLTT71IYwRwA4AcjDayuX+ljNCbcQJS0ronfMchX3o0Ysm 7g8Qtw2Ah18= =SiwQ -----END PGP SIGNATURE----- --==_Exmh_1605594354_118566P-- --===============2397150881855154641== 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 --===============2397150881855154641==--