From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759981AbXFRHg0 (ORCPT ); Mon, 18 Jun 2007 03:36:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755890AbXFRHgQ (ORCPT ); Mon, 18 Jun 2007 03:36:16 -0400 Received: from terminus.zytor.com ([192.83.249.54]:58167 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755342AbXFRHgP (ORCPT ); Mon, 18 Jun 2007 03:36:15 -0400 Message-ID: <467635D8.5060202@zytor.com> Date: Mon, 18 Jun 2007 00:35:52 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.0 (X11/20070419) MIME-Version: 1.0 To: Mike Frysinger CC: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, ak@suse.de Subject: Re: [patch] use __asm__ and __volatile__ in asm-x86_64/msr.h References: <200706180209.36762.vapier@gentoo.org> In-Reply-To: <200706180209.36762.vapier@gentoo.org> X-Enigmail-Version: 0.95.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Mike Frysinger wrote: > Most of the macros in msr.h already use __asm__ and __volatile__, this patch > brings the rest into line. This is needed since these get exported into > userspace (need to use strict __asm__ vs asm when gcc compiles with GNU > extensions turned off). > --- > diff --git a/include/asm-x86_64/msr.h b/include/asm-x86_64/msr.h > index d5c55b8..ed15d2b 100644 > --- a/include/asm-x86_64/msr.h > +++ b/include/asm-x86_64/msr.h > @@ -33,7 +33,7 @@ > > /* wrmsr with exception handling */ > #define wrmsr_safe(msr,a,b) ({ int ret__; \ > - asm volatile("2: wrmsr ; xorl %0,%0\n" \ > + __asm__ __volatile__("2: wrmsr ; xorl %0,%0\n" \ > "1:\n\t" \ > ".section .fixup,\"ax\"\n\t" \ > "3: movl %4,%0 ; jmp 1b\n\t" \ > @@ -50,7 +50,7 @@ > > #define rdmsr_safe(msr,a,b) \ > ({ int ret__; \ > - asm volatile ("1: rdmsr\n" \ > + __asm__ __volatile__ ("1: rdmsr\n" \ > "2:\n" \ > ".section .fixup,\"ax\"\n" \ > "3: movl %4,%0\n" \ NAK. This is wrong for two reasons: - MSRs are not accessible in user space. - .section .fixup is not applicable to user space. Anything MSR-related should be protected by __KERNEL__ instead. This NAK doesn't apply to rdtsc* and rdpmc* changes, however, as those instructions are legitimate in userspace. -hpa