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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 C1D18C43381 for ; Thu, 7 Mar 2019 19:00:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 92ECE20675 for ; Thu, 7 Mar 2019 19:00:02 +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="kpeVHztU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726708AbfCGTAB (ORCPT ); Thu, 7 Mar 2019 14:00:01 -0500 Received: from merlin.infradead.org ([205.233.59.134]:55604 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726520AbfCGS7s (ORCPT ); Thu, 7 Mar 2019 13:59:48 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=gGmYOEezlYoLoO0joDUV5GhkDVpNGHdbcg3KKJ8/zgw=; b=kpeVHztUq/iGy8hyqLOKVFMM/ cTiKPOslBkaiGhUXH3WpScswCI9mxDbf7Y9sUtg7wJKfcQM3cS38XfvOdFedCJnhTUK1cD1PlglOJ g38mAhLx6wfFS9UWTDvRhZilHcSrJQyoMo8C24us5clpy2i5fin/4hAD8iDZsK9baj/YT2abrVUiO dxDy4k+MPgxaaAlKUAkGtzaGohOOjg/d2j7yL5b2lJlUvxJDyGyz/mH/j+yN8sOR135tVEasCuX09 hpU4I/uoTwuZbrvoL7kz7xvMmDQTPEALZWfDa3TrlMH7IPilY2ayrQAW9qwN1WmQqzrzjHVoTYYTn 0kCe9Sdyg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1h1yEo-0000g7-Bh; Thu, 07 Mar 2019 18:59:26 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 5152C9837F2; Thu, 7 Mar 2019 19:59:22 +0100 (CET) Date: Thu, 7 Mar 2019 19:59:22 +0100 From: Peter Zijlstra To: Andy Lutomirski Cc: Linus Torvalds , Thomas Gleixner , "H. Peter Anvin" , Julien Thierry , Will Deacon , Ingo Molnar , Catalin Marinas , James Morse , valentin.schneider@arm.com, Brian Gerst , Josh Poimboeuf , Andrew Lutomirski , Borislav Petkov , Denys Vlasenko , LKML , Dmitry Vyukov , Steven Rostedt Subject: Re: [PATCH 07/20] x86/uaccess: Always inline force_valid_ss() Message-ID: <20190307185922.GA2482@worktop.programming.kicks-ass.net> References: <20190307114511.870090179@infradead.org> <20190307115159.708180729@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Thu, Mar 07, 2019 at 10:05:43AM -0800, Andy Lutomirski wrote: > On Thu, Mar 7, 2019 at 3:52 AM Peter Zijlstra wrote: > > > > arch/x86/kernel/signal.o: warning: objtool: restore_sigcontext()+0x3cc: call to force_valid_ss.isra.5() with UACCESS enabled > > > > XXX: move the callsite out of te AC=1 region instead? > > Let's move it instead. I looked at the code and it should be fine. Something like so; or did I miss something subtle? --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -132,16 +132,6 @@ static int restore_sigcontext(struct pt_ COPY_SEG_CPL3(cs); COPY_SEG_CPL3(ss); -#ifdef CONFIG_X86_64 - /* - * Fix up SS if needed for the benefit of old DOSEMU and - * CRIU. - */ - if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && - user_64bit_mode(regs))) - force_valid_ss(regs); -#endif - get_user_ex(tmpflags, &sc->flags); regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS); regs->orig_ax = -1; /* disable syscall checks */ @@ -150,6 +140,15 @@ static int restore_sigcontext(struct pt_ buf = (void __user *)buf_val; } get_user_catch(err); +#ifdef CONFIG_X86_64 + /* + * Fix up SS if needed for the benefit of old DOSEMU and + * CRIU. + */ + if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs))) + force_valid_ss(regs); +#endif + err |= fpu__restore_sig(buf, IS_ENABLED(CONFIG_X86_32)); force_iret(); @@ -441,7 +440,7 @@ static int __setup_rt_frame(int sig, str return 0; } #else /* !CONFIG_X86_32 */ -static unsigned long frame_uc_flags(struct pt_regs *regs) +static __always_inline unsigned long frame_uc_flags(struct pt_regs *regs) { unsigned long flags; @@ -461,6 +460,7 @@ static int __setup_rt_frame(int sig, str { struct rt_sigframe __user *frame; void __user *fp = NULL; + unsigned long uc_flags; int err = 0; frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp); @@ -473,9 +473,11 @@ static int __setup_rt_frame(int sig, str return -EFAULT; } + uc_flags = frame_uc_flags(regs); + put_user_try { /* Create the ucontext. */ - put_user_ex(frame_uc_flags(regs), &frame->uc.uc_flags); + put_user_ex(uc_flags, &frame->uc.uc_flags); put_user_ex(0, &frame->uc.uc_link); save_altstack_ex(&frame->uc.uc_stack, regs->sp);