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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, 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 6F8E8C43441 for ; Fri, 23 Nov 2018 20:44:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 355FC20824 for ; Fri, 23 Nov 2018 20:44:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="YdYY8hk5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 355FC20824 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject 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 S1726459AbeKXHa0 (ORCPT ); Sat, 24 Nov 2018 02:30:26 -0500 Received: from mail.skyhub.de ([5.9.137.197]:59780 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725846AbeKXHa0 (ORCPT ); Sat, 24 Nov 2018 02:30:26 -0500 Received: from zn.tnic (p200300EC2BDC9100DCA0409AA15535E1.dip0.t-ipconnect.de [IPv6:2003:ec:2bdc:9100:dca0:409a:a155:35e1]) (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 366721EC023A; Fri, 23 Nov 2018 21:44:34 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1543005874; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=FxXMLAkRavY78RZwHdRkqS++IBNNyJojGCSQFBEgaM0=; b=YdYY8hk5OvmO3lspblHF4EmtELrEUbwqg7NSjp1tcJix8qatlBbQmUV2nqUyOHsWaV43L0 x77HKkzTI2+1eI5ftjIheP8EB5cTglOA+7QTPmtiw8iU5bqy790vk5n8WrUKl0bPPRpxHV NkB3ZoRu+DaXnediWOI4sbJBV4Bejiw= Date: Fri, 23 Nov 2018 21:44:25 +0100 From: Borislav Petkov To: Guenter Roeck Cc: X86 ML , LKML , Andy Lutomirski , "H. Peter Anvin" , John Stultz , Thomas Lendacky Subject: Re: [PATCH] x86/TSC: Use RDTSCP Message-ID: <20181123204425.GN30697@zn.tnic> References: <20181119184556.11479-1-bp@alien8.de> <20181123200307.GA6223@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181123200307.GA6223@roeck-us.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 23, 2018 at 12:03:07PM -0800, Guenter Roeck wrote: > [ 0.762832] EIP: read_tsc+0x4/0x10 > [ 0.762832] Code: 00 01 00 eb 89 90 55 89 e5 5d c3 90 90 90 90 90 90 90 90 90 90 90 55 a1 44 5a 8b c5 89 e5 5d c3 8d b6 00 00 00 00 55 89 e5 57 <0f> ae f0b Where does that 'b' in f0b come from? But ok, I was able to reproduce and decode myself. So if the Code: section is correct, qemu chokes on MFENCE. [ 0.854209] Code: 90 90 90 90 90 90 90 a1 84 37 11 cd c3 8d b4 26 00 00 00 00 8d 76 00 c3 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 90 55 89 e5 <0f> ae f0 0f 31 5d c3 8d b6 00 00 00 00 55 89 e5 57 31 ff 56 53 89 All code ======== 0: 90 nop 1: 90 nop 2: 90 nop 3: 90 nop 4: 90 nop 5: 90 nop 6: 90 nop 7: a1 84 37 11 cd mov 0xcd113784,%eax c: c3 ret d: 8d b4 26 00 00 00 00 lea 0x0(%esi,%eiz,1),%esi 14: 8d 76 00 lea 0x0(%esi),%esi 17: c3 ret 18: 8d b4 26 00 00 00 00 lea 0x0(%esi,%eiz,1),%esi 1f: 8d b4 26 00 00 00 00 lea 0x0(%esi,%eiz,1),%esi 26: 90 nop 27: 55 push %ebp 28: 89 e5 mov %esp,%ebp 2a:* 0f ae f0 mfence <-- trapping instruction 2d: 0f 31 rdtsc 2f: 5d pop %ebp 30: c3 ret 31: 8d b6 00 00 00 00 lea 0x0(%esi),%esi 37: 55 push %ebp 38: 89 e5 mov %esp,%ebp 3a: 57 push %edi 3b: 31 ff xor %edi,%edi 3d: 56 push %esi 3e: 53 push %ebx 3f: 89 .byte 0x89 Doing this: asm volatile(ALTERNATIVE_2("mfence", ... fails too which confirms that P3 can't do MFENCE. I need to think about how to handle that old cruft. Thx for the report. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.