Received: by 10.192.165.156 with SMTP id m28csp19789imm; Wed, 18 Apr 2018 16:27:50 -0700 (PDT) X-Google-Smtp-Source: AIpwx4/Xs4Cth8ugWRGClLUMxgBDkR7n1u+4dr/lmbEuOVHcG5BqNKMf9EJ/LmmhlymBcyQXHQQo X-Received: by 2002:a17:902:8283:: with SMTP id y3-v6mr3887965pln.10.1524094070708; Wed, 18 Apr 2018 16:27:50 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1524094070; cv=none; d=google.com; s=arc-20160816; b=ULmCJF+rbCNJykmYMlbwV6k+QC8d0LRFrzYmedOsI7EfFjw91J3HEUQYF3v8TQfUvg m91yAvvoAkM9KPFLNBBfBHQevCCHRMWtvssMoM0bTlnyDvZeIAxyZrJvYT4giNUgvM/6 17TyX5CtS1EYZa7v3+v6GlkkMMUDfNvrLFJrMDdK5gZYnP44N0buFRJ2Gk3juVlK9GFK DZrrWPSUaTXyxA1c1IcVgjuv8Rtha3mgL/ik6Gm7UA8N5Nf2sBEYlTObAbW4nQg2Ug20 rFV8LQYFCipmz/TPW2Xoz+S3maT7KOiI+UXDayjamu2PNa4LReuii4CBp+6z+KTI0+23 mVVQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:mime-version:user-agent:message-id :in-reply-to:date:references:subject:cc:to:from :arc-authentication-results; bh=Y6vDmzOGPF7aTzUs7gR6ZJ0UPZuz4YljP53JHWx15y0=; b=HJAxW/Acc0aTM9KHpsnjy6dMO3rm/aCyIM8HkfBq3S8slia5EXzUEP/H94JQM4/GbM aijZRRdG2wC8G6xP4lhjFEOrWJdYZIjOJNTO2Ei3Vu3iHrr7GWZkQqzYGdi59+19oxxH miygkuWfsJbHTUMyu0qGXLg6VTaYYzpywAtTbgOKWqMzlSgKl8+FfL//49vqqDXWizVS VcLMwuo/8BID3PwiQoytcpsz208LMrEcUtBS6/sKfG8cUBMK/ES7eiwFy3KixU9EkSbp VUPLEdMMUZ9tX/cm4Yw5rQM3sH73HsrZxDyuTuM5cDO/QdUZhRu8DytO9cwFVr1TsoOb 5kJw== ARC-Authentication-Results: i=1; mx.google.com; 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 Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id g34-v6si2132208pld.411.2018.04.18.16.27.34; Wed, 18 Apr 2018 16:27:50 -0700 (PDT) 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; 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 S1753206AbeDRX0W (ORCPT + 99 others); Wed, 18 Apr 2018 19:26:22 -0400 Received: from mga03.intel.com ([134.134.136.65]:4966 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753145AbeDRX0U (ORCPT ); Wed, 18 Apr 2018 19:26:20 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Apr 2018 16:26:20 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,467,1517904000"; d="scan'208";a="48989804" Received: from tassilo.jf.intel.com (HELO tassilo.localdomain) ([10.7.201.126]) by orsmga001.jf.intel.com with ESMTP; 18 Apr 2018 16:26:19 -0700 Received: by tassilo.localdomain (Postfix, from userid 1000) id CA582301BFD; Wed, 18 Apr 2018 16:26:19 -0700 (PDT) From: Andi Kleen To: Joerg Roedel Cc: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds , 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 , aliguori@amazon.com, daniel.gruss@iaik.tugraz.at, hughd@google.com, keescook@google.com, Andrea Arcangeli , Waim@linux.intel.com Subject: Re: [PATCH 03/35] x86/entry/32: Load task stack from x86_tss.sp1 in SYSENTER handler References: <1523892323-14741-1-git-send-email-joro@8bytes.org> <1523892323-14741-4-git-send-email-joro@8bytes.org> Date: Wed, 18 Apr 2018 16:26:19 -0700 In-Reply-To: <1523892323-14741-4-git-send-email-joro@8bytes.org> (Joerg Roedel's message of "Mon, 16 Apr 2018 17:24:51 +0200") Message-ID: <87k1t4t7tw.fsf@linux.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Joerg Roedel writes: > From: Joerg Roedel > > We want x86_tss.sp0 point to the entry stack later to use > it as a trampoline stack for other kernel entry points > besides SYSENTER. > > So store the task stack pointer in x86_tss.sp1, which is > otherwise unused by the hardware, as Linux doesn't make use > of Ring 1. Seems like a hack. Why can't that be stored in a per cpu variable? -Andi