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[209.132.180.67]) by mx.google.com with ESMTP id bg8-v6si1747207plb.748.2018.02.09.09.06.06; Fri, 09 Feb 2018 09:06:21 -0800 (PST) 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=fail header.i=@gmail.com header.s=20161025 header.b=Fc+FRolY; 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 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752387AbeBIRFG (ORCPT + 99 others); Fri, 9 Feb 2018 12:05:06 -0500 Received: from mail-io0-f196.google.com ([209.85.223.196]:34059 "EHLO mail-io0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751150AbeBIRFF (ORCPT ); Fri, 9 Feb 2018 12:05:05 -0500 Received: by mail-io0-f196.google.com with SMTP id x188so3817553iod.1 for ; Fri, 09 Feb 2018 09:05:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=5xC0LWiP49tHtE62343SVaW62QIKt1lVjPDfW3PdScU=; b=Fc+FRolYztgS5ETuVy4ol40GUNZX/pV9jMDhpHcJRG5A3XyOMDcSqSapT0S/aoXXUv JsSvDrgHtqUxgeGt6QeT18OSM2MUKr92l8jBtzD8HfWvn3NpQECa5TpRs5s4HJ0BZbP3 T8cVU4iH9sx7A6TavxPjkZc6azf+xQocEqQZdaWaSH2fd2L9fyoTD9M8rx9/82YbD+5L 6z2dc7yVBaEpKh7Y9bGbAGtFGzsJJIdlVRW651edhIL/JkdskcYhR/hae+xRn/e0hXHb 6VDc3Y4aZdGKrdBsOBf5/1o5B7JzBfN6ocaNyCVrIpwvL/qktB8xVhypS1UKMnFZ72Mg fToQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=5xC0LWiP49tHtE62343SVaW62QIKt1lVjPDfW3PdScU=; b=Q6b256GjHATvf3p7H0bvzIlTvH3URBawzUDGwR6t+64N0itKM6ZvbKGtVAI3+Xkx+d W/95MPZjiBScuKu85p/gccVFiq9c4WdIyw8Ohn2aTLMa32+YjwuaroGQ7xZwgz9fHUYB ZrSp9rJjKkYrL+8DeJF3/snhbNUh8q91bBVLosRTap8MHprLOqJCqb1lZR6OhnmHzJ2t hwS5H2WpmCZpdgLxHfahdQod6TjkI0K4TBE6Jj2+/SeLoluLVQcylEdl9Z9sIeDyrByI qGzAKk1Pp6S8ot5ObC79cDY2JoBVwqEMSrtvbX/M8R30FTGtafFjXwOLIRK/chTpRyQn T4WA== X-Gm-Message-State: APf1xPCI1xAH9PK2vJOvTe1W2kXGv6bBmCe7ngx2MN0eGVhNrOQhJWDX NShTJX24zjmwEEr4qiq8dKr84V6SLBIZj3mheN8= X-Received: by 10.107.183.78 with SMTP id h75mr3861520iof.201.1518195904173; Fri, 09 Feb 2018 09:05:04 -0800 (PST) MIME-Version: 1.0 Received: by 10.107.59.196 with HTTP; Fri, 9 Feb 2018 09:05:02 -0800 (PST) In-Reply-To: <1518168340-9392-10-git-send-email-joro@8bytes.org> References: <1518168340-9392-1-git-send-email-joro@8bytes.org> <1518168340-9392-10-git-send-email-joro@8bytes.org> From: Linus Torvalds Date: Fri, 9 Feb 2018 09:05:02 -0800 X-Google-Sender-Auth: eXQDFw9VX0uBcOBnj5bf0zB2eg4 Message-ID: Subject: Re: [PATCH 09/31] x86/entry/32: Leave the kernel via trampoline stack To: Joerg Roedel Cc: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , "the arch/x86 maintainers" , Linux Kernel Mailing List , linux-mm , Andy Lutomirski , Dave Hansen , Josh Poimboeuf , Juergen Gross , Peter Zijlstra , Borislav Petkov , Jiri Kosina , Boris Ostrovsky , Brian Gerst , David Laight , Denys Vlasenko , Eduardo Valentin , Greg KH , Will Deacon , "Liguori, Anthony" , Daniel Gruss , Hugh Dickins , Kees Cook , Andrea Arcangeli , Waiman Long , Pavel Machek , Joerg Roedel Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 9, 2018 at 1:25 AM, Joerg Roedel wrote: > + > + /* Copy over the stack-frame */ > + cld > + rep movsb Ugh. This is going to be horrendous. Maybe not noticeable on modern CPU's, but the whole 32-bit code is kind of pointless on a modern CPU. At least use "rep movsl". If the kernel stack isn't 4-byte aligned, you have issues. Linus