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,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, 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 E5B37C432C0 for ; Wed, 20 Nov 2019 12:39:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B30E62251F for ; Wed, 20 Nov 2019 12:39:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="OjXmSLn6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729826AbfKTMje (ORCPT ); Wed, 20 Nov 2019 07:39:34 -0500 Received: from mail.skyhub.de ([5.9.137.197]:45330 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727736AbfKTMje (ORCPT ); Wed, 20 Nov 2019 07:39:34 -0500 Received: from zn.tnic (p200300EC2F0D8C00B1B17C12861BCCA4.dip0.t-ipconnect.de [IPv6:2003:ec:2f0d:8c00:b1b1:7c12:861b:cca4]) (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 8C9BE1EC0CE3; Wed, 20 Nov 2019 13:39:32 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1574253572; 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=zp+1xALzK6MVb4JuJSTpKsxknVwYBFmIQv2YEQLs+rY=; b=OjXmSLn6Lwc3Qnwt6j+mOJxv7SMfG3DzPADdwFyKrncZNuWJWJ0tqJsXG392WhdmlR6Evd BQrXpkEmH+Na1AC7P+3UIrPSix03glvJriHR3KbwgngWNmjri35erJNP+In39ZVOPv6Axc ZREtaMyGoowz1M1plXurckDz4qfruFo= Date: Wed, 20 Nov 2019 13:39:26 +0100 From: Borislav Petkov To: Ingo Molnar Cc: Jann Horn , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , the arch/x86 maintainers , Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , kasan-dev , kernel list , Andrey Konovalov , Andy Lutomirski , Sean Christopherson , Andi Kleen Subject: Re: [PATCH v3 2/4] x86/traps: Print non-canonical address on #GP Message-ID: <20191120123926.GE2634@zn.tnic> References: <20191120103613.63563-1-jannh@google.com> <20191120103613.63563-2-jannh@google.com> <20191120111859.GA115930@gmail.com> <20191120123058.GA17296@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20191120123058.GA17296@gmail.com> 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 Wed, Nov 20, 2019 at 01:30:58PM +0100, Ingo Molnar wrote: > > * Jann Horn wrote: > > > You mean something like this? > > > > ======================== > > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c > > index 9b23c4bda243..16a6bdaccb51 100644 > > --- a/arch/x86/kernel/traps.c > > +++ b/arch/x86/kernel/traps.c > > @@ -516,32 +516,36 @@ dotraplinkage void do_bounds(struct pt_regs > > *regs, long error_code) > > * On 64-bit, if an uncaught #GP occurs while dereferencing a non-canonical > > * address, return that address. > > */ > > -static unsigned long get_kernel_gp_address(struct pt_regs *regs) > > +static bool get_kernel_gp_address(struct pt_regs *regs, unsigned long *addr, > > + bool *non_canonical) > > Yeah, that's pretty much the perfect end result! Why do we need the bool thing? Can't we rely on the assumption that an address of 0 is the error case and use that to determine whether the resolving succeeded or not? -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette