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=-11.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 7CD45C433F5 for ; Tue, 14 Sep 2021 18:01:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C65661029 for ; Tue, 14 Sep 2021 18:01:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231725AbhINSCc (ORCPT ); Tue, 14 Sep 2021 14:02:32 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:31572 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230092AbhINSC2 (ORCPT ); Tue, 14 Sep 2021 14:02:28 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631642469; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=3VFDTiYoRlzqKicgJ4/TFx2uKS2MR5n6U8naB6Hc7Vc=; b=ggpiQ9S38VjMGm/H1tBO+8c0gOlywnRDNYTdUtTmBBZKFwbDtsiIJbx2A7kBpXUuNQfzmx LyE8PWiYheiqzcbocvMR4zj0gGtAehjRlWT834gjSk5hv1H2PYLmKOSNKjsTUITRTld7PF Qx8+CrzwdTkR3lGdV9kahB5I4p2Esl0= Received: from mail-io1-f71.google.com (mail-io1-f71.google.com [209.85.166.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-497-8EGhwLZoPRuA7mJhMSyByQ-1; Tue, 14 Sep 2021 14:01:08 -0400 X-MC-Unique: 8EGhwLZoPRuA7mJhMSyByQ-1 Received: by mail-io1-f71.google.com with SMTP id e18-20020a6b7312000000b005be766a70dbso16889503ioh.19 for ; Tue, 14 Sep 2021 11:01:08 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=3VFDTiYoRlzqKicgJ4/TFx2uKS2MR5n6U8naB6Hc7Vc=; b=cFHdR0SFHIpd6V5uCuNLlz4EFFsYcaYPX60efrstcS3B/zY6OWUEY8rky5V46EKtR/ WyvLIDXyPVbGLQwtuHlR/ShpsZhsZ2ketNXwDeSt87s3BXsWRF0fxCQVTtpNx6TaLw/T +U/smsoyJA4qP8eWuKk/wqXRdUNUzqNiIwJr+o8GpvAdWOpyAlJ5zCBgTU8K5aZ69lU7 Q/a47x2K21R0lcDpIi+ALwjTHum4blF4z6E2oJIHXV2X0onsHFHLY+BCNkVYqF2y5g6K omP9fB1nRmMzXa9ih8kxMC0f8fxcmmjLZplT/W56Vw9QIDGi7XdXd/zqEz12LceWHjJG qbBg== X-Gm-Message-State: AOAM533HriHiKcWbSp8giJF8mjnNrVcZT/Yvfry7pqZB/6z9wadMorvI x85owAG5BL69myvmoiR4YJE8tl8LbEwKPdgxgorOq7ZYxOPiO5CsATQw0SGzuTxmXW6d8KS9pwZ LeYIfZVw1jt62BW6Rb9ig/0RztqM= X-Received: by 2002:a05:6638:14cf:: with SMTP id l15mr15600438jak.8.1631642467564; Tue, 14 Sep 2021 11:01:07 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyNTD3sI+K8LSInPshZeuGeEclDDWRggxV9m08JblPlHnXoPVdbjOI8oGhhX5fWd+8Dq1ETAg== X-Received: by 2002:a05:6638:14cf:: with SMTP id l15mr15600422jak.8.1631642467342; Tue, 14 Sep 2021 11:01:07 -0700 (PDT) Received: from t490s ([2607:fea8:56a2:9100::d35a]) by smtp.gmail.com with ESMTPSA id r13sm7737191ilh.80.2021.09.14.11.01.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Sep 2021 11:01:06 -0700 (PDT) Date: Tue, 14 Sep 2021 14:01:05 -0400 From: Peter Xu To: Nicolas Saenz Julienne Cc: linux-rt-users@vger.kernel.org, williams@redhat.com, jkacur@redhat.com, Punit Agrawal Subject: Re: [PATCH] oslat: Avoid out-of-order memory accesses to precede counter read Message-ID: References: <20210914175542.338429-1-nsaenzju@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210914175542.338429-1-nsaenzju@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org On Tue, Sep 14, 2021 at 07:55:42PM +0200, Nicolas Saenz Julienne wrote: > In arm64 it's possible for the processor to access memory appearing in > program order after the read of the counter before the counter has been > read. This would skew the counter value to a later point than intended. > > Fix this my adding an isb() following the counter read instruction. > > Suggested-by: Punit Agrawal > Signed-off-by: Nicolas Saenz Julienne Acked-by: Peter Xu -- Peter Xu