From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752527AbaKDTdT (ORCPT ); Tue, 4 Nov 2014 14:33:19 -0500 Received: from mail-pd0-f176.google.com ([209.85.192.176]:60938 "EHLO mail-pd0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751430AbaKDTdS (ORCPT ); Tue, 4 Nov 2014 14:33:18 -0500 Message-ID: <545929F9.7010301@amacapital.net> Date: Tue, 04 Nov 2014 11:33:13 -0800 From: Andy Lutomirski User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Jan Beulich , mingo@elte.hu, tglx@linutronix.de, hpa@zytor.com CC: linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/2] x86-64: allow using RIP-relative addressing for per-CPU data References: <5458A12C0200007800044A97@mail.emea.novell.com> In-Reply-To: <5458A12C0200007800044A97@mail.emea.novell.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/04/2014 12:49 AM, Jan Beulich wrote: > Observing that per-CPU data (in the SMP case) is reachable by > exploiting 64-bit address wraparound, these two patches > arrange for using the one byte shorter RIP-relative addressing > forms for the majority of per-CPU accesses. > > 1: handle PC-relative relocations on per-CPU data > 2: use RIP-relative addressing for most per-CPU accesses > > Signed-off-by: Jan Beulich > I'm lost here. Can you give an example of a physical and virtual address of an instruction, the address within the gs segment, and why the relocations are backwards? --Andy