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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 73B43C3A5A6 for ; Mon, 23 Sep 2019 13:33:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 49ECE20820 for ; Mon, 23 Sep 2019 13:33:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="iXobH4vL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437487AbfIWNd4 (ORCPT ); Mon, 23 Sep 2019 09:33:56 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:50220 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2437100AbfIWNd4 (ORCPT ); Mon, 23 Sep 2019 09:33:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=4oYYvhMZLswDD/qjuPlU5roe59xl0+W+kHzpJNuHTkk=; b=iXobH4vLyUWuAatRn/YNyFm19 67BChJmm/usupfpf5trKfdtTguX18shVRtaIa+IWb8JHFn8kYVpArMI9JI2gsBLooElnoYb8QsjDv /SOLDcq/e1CR2vJoDEiyOkAfmRULtqvsRN8nq1fHSDNkMvoowJpVt4rwMIgmAc9q9SQqAP/IWRaFd glori5/UnJ96kIUmcf943s1uwe+F8pO4OWZ1ip4FoOA0Hpnkl7H0jxI+vZrmZrSGsjuVCc6jPcvZH ydG/ABzBv6/ax5R3ZrJ46l5lMBiojuJ7bOJp7HKyWS3bLljJpydZY9f9F0dRZxOfPTMFRW98NyIqe KWihAqQ3w==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.2 #3 (Red Hat Linux)) id 1iCOTS-0005b5-Iy; Mon, 23 Sep 2019 13:33:54 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id E33F3303DFD; Mon, 23 Sep 2019 15:33:06 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1843020D80D42; Mon, 23 Sep 2019 15:33:52 +0200 (CEST) Date: Mon, 23 Sep 2019 15:33:52 +0200 From: Peter Zijlstra To: Josh Poimboeuf Cc: Randy Dunlap , Mark Brown , Linux Next Mailing List , Linux Kernel Mailing List Subject: Re: linux-next: Tree for Sep 18 (objtool) Message-ID: <20190923133352.GI2332@hirez.programming.kicks-ass.net> References: <20190918221053.GV2596@sirena.co.uk> <20190923092024.GI2349@hirez.programming.kicks-ass.net> <20190923124901.3ayejcis5ijrsvbx@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190923124901.3ayejcis5ijrsvbx@treble> 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 Mon, Sep 23, 2019 at 07:49:01AM -0500, Josh Poimboeuf wrote: > On Mon, Sep 23, 2019 at 11:20:24AM +0200, Peter Zijlstra wrote: > > On Wed, Sep 18, 2019 at 09:04:21PM -0700, Randy Dunlap wrote: > > > On 9/18/19 3:10 PM, Mark Brown wrote: > > > > Hi all, > > > > > > > > Changes since 20190917: > > > > > > > > > > on x86_64: > > > > > > drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: i915_gem_execbuffer2_ioctl()+0x2fb: call to gen8_canonical_addr() with UACCESS enabled > > > > I'm thinking that comes from: > > > > offset = gen8_canonical_addr(offset & ~UPDATE); > > if (unlikely(__put_user(offset, &urelocs[r-stack].presumed_offset))) { > > > > however, per commit 6ae865615fc4 (and 2a418cf3f5f1) the compiler really > > should not be sticking gen8_canonical_addr() after __uaccess_begin(). > > > > /me puzzled... > > I think you're looking at the wrong code. It has user_access_begin/end > around it: > > if (!user_access_begin(user_exec_list, count * sizeof(*user_exec_list))) > goto end; > > for (i = 0; i < args->buffer_count; i++) { > if (!(exec2_list[i].offset & UPDATE)) > continue; > > exec2_list[i].offset = > gen8_canonical_addr(exec2_list[i].offset & PIN_OFFSET_MASK); > unsafe_put_user(exec2_list[i].offset, > &user_exec_list[i].offset, > end_user); > } > end_user: > user_access_end(); > Oh, Duh... Yeah, so the alternative to your solution is to do 2 loops. Not sure which would be better.