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=-2.5 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 E6EACC169C4 for ; Tue, 29 Jan 2019 13:20:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B62D020882 for ; Tue, 29 Jan 2019 13:20:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725601AbfA2NUU (ORCPT ); Tue, 29 Jan 2019 08:20:20 -0500 Received: from mga06.intel.com ([134.134.136.31]:59450 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725355AbfA2NUU (ORCPT ); Tue, 29 Jan 2019 08:20:20 -0500 X-Amp-Result: UNSCANNABLE X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Jan 2019 05:20:19 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,537,1539673200"; d="scan'208";a="138829651" Received: from jsakkine-mobl1.tm.intel.com (HELO localhost) ([10.237.50.127]) by fmsmga002.fm.intel.com with ESMTP; 29 Jan 2019 05:20:17 -0800 Date: Tue, 29 Jan 2019 15:20:16 +0200 From: Jarkko Sakkinen To: Linus Torvalds Cc: Jason Gunthorpe , James Bottomley , linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, Linux List Kernel Mailing Subject: Re: Getting weird TPM error after rebasing my tree to security/next-general Message-ID: <20190129132016.GA1602@linux.intel.com> References: <20190118142559.GA4080@linux.intel.com> <1547849358.2794.90.camel@HansenPartnership.com> <20190120160413.GB30478@linux.intel.com> <20190122010218.GA26713@linux.intel.com> <20190122025836.GH25163@ziepe.ca> <20190122132910.GA2720@linux.intel.com> <20190123153638.GA8727@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Thu, Jan 24, 2019 at 07:43:30AM +1300, Linus Torvalds wrote: > On Thu, Jan 24, 2019 at 4:36 AM Jarkko Sakkinen > wrote: > > > > > > Is it just that this particular hardware always happened to trigger > > > the ERMS case (ie "rep movsb")? > > > > This is the particular snippet in question: > > > > memcpy_fromio(buf, priv->rsp, 6); > > expected = be32_to_cpup((__be32 *) &buf[2]); > > if (expected > count || expected < 6) > > return -EIO; > > Ok, strange. > > So what *used* to happen is that the memcpy_fromio() would just expand > as a "memcpy()", and in this case, gcc would then inline the memcpy(). > In fact, gcc does it as a 4-byte access and a two-byte access from > what I can tell. I verified, and it is exactly as you stated: 0xffffffff814aaa33 <+51>: mov (%rax),%edx 0xffffffff814aaa35 <+53>: mov %edx,0x0(%rbp) 0xffffffff814aaa38 <+56>: movzwl 0x4(%rax),%eax 0xffffffff814aaa3c <+60>: mov %ax,0x4(%rbp) And your new version does exactly the same thing to the first six bytes (with different opcode, but the same memory access pattern). /Jarkko