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=-5.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 8EEEDC76186 for ; Wed, 24 Jul 2019 16:54:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F94021841 for ; Wed, 24 Jul 2019 16:54:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="HfGrcjQ4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727800AbfGXQyw (ORCPT ); Wed, 24 Jul 2019 12:54:52 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:34831 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727055AbfGXQyv (ORCPT ); Wed, 24 Jul 2019 12:54:51 -0400 Received: by mail-wr1-f67.google.com with SMTP id y4so47770553wrm.2 for ; Wed, 24 Jul 2019 09:54:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=GGnDbdb1w8mdDXJnIzPOA9I6KzGS82PK72BzW8rS+sA=; b=HfGrcjQ4nMFBSnwAv3eptOIQkUx6A6Gyr8zx3ikCLLk/yGT6rHRMMyV/7bAFlpQIWn rg5NTLg449T4KeZeGrnsFhRaIirq6d2lixbOn85PCMUaUqdxOGRGwx3drhIKMLXZt9LP Sc14b+391Qf4dfFYAr1b9J58sOjDWz4m3Y7MDkXqq0dkOJ3LOSRQSCZt7ILZIRQKLWF5 aKDTgbdeHrBCGMBS5tWRSN+i2ljA2b66wxP1jsuRLSKAmi7vNbkpnfOIuSeoN2hB9Vqj 6C494UCj+Tx+zTAqP3yI24cnKiS6oDFZJ4NU6cAXZCHOpDaoNF9X892SwQOIf46atwQf MFkA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=GGnDbdb1w8mdDXJnIzPOA9I6KzGS82PK72BzW8rS+sA=; b=eVEGBoV96wr6Cq2S/qAzsAHR7k1j5fTfcW4bBG9muQZ8RUgM3nJ0qbpRS0B46983Dh FMBG/SGene8mi/TFA4RtBxXzH7UWaoyKG03KjNYb8mnhEGAwb2EwvnlHTPTrE/PnU4cx 3a1LVizTAWhREm1Nsj2R65JW9U0BJjIUCYujbEkr4w7KlCuQd9ZJ4M4MJ9LrtwgS2ekm mYulpML++QHXwXcqUbZItnYt+b0JCXaatYYh37NCUATWBNvkFOcQxbkN/PGedkbrbnq/ 1feiVFZZwvSPYUnAdfIeK/z0GRBomvTNBoyc2yJ6NXxC2Bt4ZzB0NqC1YCKFFdw48Ao0 y5Qg== X-Gm-Message-State: APjAAAW4Y1d0gqcGlFqqfB2Hl5fx0HfVYM+OcsGflrfbrEw9QcffQhwW 00FQ7WGRGNing1lz9JEsuaM= X-Google-Smtp-Source: APXvYqzZHZpbVplb8GHdoH7GYDgxJFDlO7e94sMpgOxhe9ybJ4LWMIZzKPnJpFflUf1OqztzynYvzQ== X-Received: by 2002:adf:f206:: with SMTP id p6mr16153631wro.216.1563987289028; Wed, 24 Jul 2019 09:54:49 -0700 (PDT) Received: from archlinux-threadripper ([2a01:4f8:222:2f1b::2]) by smtp.gmail.com with ESMTPSA id c1sm100119741wrh.1.2019.07.24.09.54.48 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 24 Jul 2019 09:54:48 -0700 (PDT) Date: Wed, 24 Jul 2019 09:54:46 -0700 From: Nathan Chancellor To: Peter Zijlstra Cc: Josh Poimboeuf , Thomas Gleixner , LKML , Nick Desaulniers , clang-built-linux , x86@kernel.org, Arnd Bergmann , Sedat Dilek , Linus Torvalds Subject: Re: [PATCH] objtool: Improve UACCESS coverage Message-ID: <20190724165446.GA110233@archlinux-threadripper> References: <20190724023946.yxsz5im22fz4zxrn@treble> <20190724074732.GJ3402@hirez.programming.kicks-ass.net> <20190724125525.kgybu3nnpvwlcz2c@treble> <20190724133516.GB31381@hirez.programming.kicks-ass.net> <20190724141040.GA31425@hirez.programming.kicks-ass.net> <20190724164821.GB31425@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190724164821.GB31425@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 24, 2019 at 06:48:21PM +0200, Peter Zijlstra wrote: > On Wed, Jul 24, 2019 at 04:10:40PM +0200, Peter Zijlstra wrote: > > And that most certainly should trigger... > > > > Let me gdb that objtool thing. > > --- > Subject: objtool: Improve UACCESS coverage > > A clang build reported an (obvious) double CLAC while a GCC build did > not; it turns out we only re-visit instructions if the first visit was > with AC=0. If OTOH the first visit was with AC=1, we completely ignore > any subsequent visit, even when it has AC=0. > > Fix this by using a visited mask, instead of boolean and (explicitly) > mark the AC state. > > $ ./objtool check -b --no-fp --retpoline --uaccess ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o > ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x22: redundant UACCESS disable > ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xea: (alt) > ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0xffffffffffffffff: (branch) > ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xd9: (alt) > ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xb2: (branch) > ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0x39: (branch) > ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0x0: <=== (func) > > Reported-by: Josh Poimboeuf > Reported-by: Thomas Gleixner > Signed-off-by: Peter Zijlstra (Intel) This doesn't regress clang and I see the warning on GCC now too. Tested-by: Nathan Chancellor