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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 10CC3C4321E for ; Fri, 7 Sep 2018 09:36:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B9AC2206BB for ; Fri, 7 Sep 2018 09:36:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B9AC2206BB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=alien8.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727631AbeIGOQM (ORCPT ); Fri, 7 Sep 2018 10:16:12 -0400 Received: from mail.skyhub.de ([5.9.137.197]:38546 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726099AbeIGOQM (ORCPT ); Fri, 7 Sep 2018 10:16:12 -0400 X-Virus-Scanned: Nedap ESD1 at mail.skyhub.de Received: from mail.skyhub.de ([127.0.0.1]) by localhost (blast.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id TgufEiMNR6TT; Fri, 7 Sep 2018 11:36:04 +0200 (CEST) Received: from zn.tnic (p200300EC2BCC4300329C23FFFEA6A903.dip0.t-ipconnect.de [IPv6:2003:ec:2bcc:4300:329c:23ff:fea6:a903]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 858111EC0104; Fri, 7 Sep 2018 11:36:04 +0200 (CEST) Date: Fri, 7 Sep 2018 11:35:57 +0200 From: Borislav Petkov To: Andy Lutomirski Cc: x86@kernel.org, LKML , Dave Hansen , Adrian Hunter , Alexander Shishkin , Arnaldo Carvalho de Melo , Linus Torvalds , Josh Poimboeuf , Joerg Roedel , Jiri Olsa , Andi Kleen , Peter Zijlstra Subject: Re: [PATCH v2 3/3] x86/pti/64: Remove the SYSCALL64 entry trampoline Message-ID: <20180907093557.GC12849@zn.tnic> References: <8c7c6e483612c3e4e10ca89495dc160b1aa66878.1536015544.git.luto@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <8c7c6e483612c3e4e10ca89495dc160b1aa66878.1536015544.git.luto@kernel.org> User-Agent: Mutt/1.9.5 (2018-04-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 03, 2018 at 03:59:44PM -0700, Andy Lutomirski wrote: > The SYSCALL64 trampoline has a couple of nice properties: > > - The usual sequence of SWAPGS followed by two GS-relative accesses to > set up RSP is somewhat slow because the GS-relative accesses need > to wait for SWAPGS to finish. The trampoline approach allows > RIP-relative accesses to set up RSP, which avoids the stall. ... > diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c > index 31341ae7309f..7e79154846c8 100644 > --- a/arch/x86/mm/pti.c > +++ b/arch/x86/mm/pti.c > @@ -434,11 +434,42 @@ static void __init pti_clone_p4d(unsigned long addr) > } > > /* > - * Clone the CPU_ENTRY_AREA into the user space visible page table. > + * Clone the CPU_ENTRY_AREA and associated data into the user space visible > + * page table. > */ > static void __init pti_clone_user_shared(void) > { > + unsigned cpu; Make that unsigned int cpu; Otherwise, patches removing complex code are always good! Reviewed-by: Borislav Petkov -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.