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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FSL_HELO_FAKE,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 84629C2D0DB for ; Tue, 28 Jan 2020 20:14:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 294B220708 for ; Tue, 28 Jan 2020 20:14:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580242461; bh=4SM/2bdnv+DFbeLsTV2fqxBw/Yh8zMSu+SuA3eOC/1M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Nz5NkWFgKkofjjDEq9ME0XRyO/ea8Lq2zLEXAVxORpz040nwTwIlGi5sUMMAgYHVY efNZRk1xpCG9DrWzHaQgXM4okDmmD1TABMgQe4q4EqNFoNfs5JIzgUzqlpbAPVAnoe NTefQYdyn1Sm7mksb4Gx4lr8PZsbjQMLQ+mu1+jA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726391AbgA1UOU (ORCPT ); Tue, 28 Jan 2020 15:14:20 -0500 Received: from mail-wm1-f65.google.com ([209.85.128.65]:51305 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726182AbgA1UOU (ORCPT ); Tue, 28 Jan 2020 15:14:20 -0500 Received: by mail-wm1-f65.google.com with SMTP id t23so3925411wmi.1 for ; Tue, 28 Jan 2020 12:14:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=y/ed9DUQExY9n11iK5mbjNhe8YjTArUKxK4NVRoKnXc=; b=VybF2xFfvJabsCgeo4SwZvw7v3ouC7JxqF/KS3M/WSwRoFOd7xjvrwH1s21UNAzSr6 PvSHkGRqgb+9qYFMQ92KJMdcU9vovmhiCjAWorvdueMlBH9kqGaNE8VInQow7shLsq0q OmPP/xDOKziicv0Je1CWw9Im8WFpGIGy6tWaaRAzZjylJOd1vHf1knc4+aw9RezZzPFW Fv0HHHno4AyyB0b0OohgcFlLB1tw2HI0Kxs7wkefTVVElyXC45XJTdUDvap1KoxV27Xn Zav9SN/DK1pv0S0ANaovA4Qz7d3wmwh4pJz/cW+iz6F57YqsH7KYeoe48okthhIK/Md5 duzw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=y/ed9DUQExY9n11iK5mbjNhe8YjTArUKxK4NVRoKnXc=; b=ZUxdG7kXFoC+i7RjspbadOt+D0dBeeZMkeOb7+sVHxyTvZyV9Ezbm0mu9UbV7vl9Nu 2LbOFGsn2LQvW0qV+QvcWaHkQQlKZSX5BegV8LeHkLgKpcXRt6yu/J4lV0RSJd/XPHpb HVXJZZQRQxi+sJHijjZWfu0R1shTcUifTW0p98PnHIRwBGREfq1jCR7MR/fSo9QyTOf/ pd+8wbkAVaHIVQ5UM1JY7bVlFDoQhdL0ZpgUfU8hztr6agfPsYrV0bPLswSHVpzkV4CX cqIDWk6aYqOH73A5CHwJMb7XFKfvPAg+kqC0L9tPeTQBBHImspJV8xdy4iNTF8AWBW0R P40Q== X-Gm-Message-State: APjAAAU6RpRfDLth7op6mexlbMfD+NuvKeQuICIre6IdFZoqmF0Cs6LA cDTHVm5ny35P4R1k5yFkhf8= X-Google-Smtp-Source: APXvYqzZNMu6ODSHvWgoDTZLaLu1muxIJVdFQ3ZzjU2etpeEsDzN9DZZHHilsFHH+kkujz7zq4vDOg== X-Received: by 2002:a7b:c4cc:: with SMTP id g12mr7336168wmk.68.1580242458477; Tue, 28 Jan 2020 12:14:18 -0800 (PST) Received: from gmail.com (54033286.catv.pool.telekom.hu. [84.3.50.134]) by smtp.gmail.com with ESMTPSA id v3sm27201166wru.32.2020.01.28.12.14.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jan 2020 12:14:17 -0800 (PST) Date: Tue, 28 Jan 2020 21:14:15 +0100 From: Ingo Molnar To: Linus Torvalds Cc: Tony Luck , Borislav Petkov , Linux Kernel Mailing List , Thomas Gleixner , Borislav Petkov , Peter Zijlstra , Andrew Morton Subject: Re: [GIT PULL] x86/asm changes for v5.6 Message-ID: <20200128201415.GA89586@gmail.com> References: <20200128165906.GA67781@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Linus Torvalds wrote: > On Tue, Jan 28, 2020 at 11:51 AM Linus Torvalds > wrote: > > > > ALTERNATIVE_2 \ > > "cmp $680, %rdx ; jb 3f ; cmpb %dil, %sil; je 4f", \ > > "movq %rdx, %rcx ; rep movsb; retq", X86_FEATURE_FSRM, \ > > "cmp $0x20, %rdx; jb 1f; movq %rdx, %rcx; rep movsb; retq", X86_FEATURE_ERMS > > Note the UNTESTED part. > > In particular, I didn't check what the priority for the alternatives > is. Since FSRM being set always implies ERMS being set too, it may be > that the ERMS case is always picked with the above code. > > So maybe the FSRM and ERMS lines need to be switched around, and > somebody should add a comment to the ALTERNATIVE_2 macro about the > priority rules for feature1 vs feature2 when both are set.. > > IOW, testing most definitely required for that patch suggestion of mine.. Understood, thanks! Ingo