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 0405AC43381 for ; Thu, 7 Mar 2019 12:55:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C484620675 for ; Thu, 7 Mar 2019 12:55:44 +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="s/szqWVg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726277AbfCGMzn (ORCPT ); Thu, 7 Mar 2019 07:55:43 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:47780 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726101AbfCGMzm (ORCPT ); Thu, 7 Mar 2019 07:55:42 -0500 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=XSZkNgeDlJsSG53OA6qoCCgwdL5s/unQsXVqrhxGf3g=; b=s/szqWVgPjSw+NdeXh8m66Gbm 5HQ8jq8YVSLW9+cGqiS5j8m8/d0hFM2+vg+AC7yl/OStXBqvv4QadDsF85CntjJOFjge2YIkjySPI THw28KweEi9WKjPzjTtpnSErECoaMeqxGI/BBVZEopdwa6M8r+UxlVtuYEHvUzHRcf3eg266sdQEi 3vVOOeD5S0+iV1CE/LW8cezUKzCqECCEJhiOFUKbLEKdbfOnNwLQdxv5csBKagB6RK5sBtESZWNJ1 aNMWILHK59wTyPhA6MNF39oD2hR0RPeLg364jbgUsXxd+0uY2I7Q3+w/csmR6bqb5E4L1IPeS5CCS gQuCsP2rg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1h1sYb-0001YQ-S8; Thu, 07 Mar 2019 12:55:30 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 93A4020297BBE; Thu, 7 Mar 2019 13:55:26 +0100 (CET) Date: Thu, 7 Mar 2019 13:55:26 +0100 From: Peter Zijlstra To: torvalds@linux-foundation.org, tglx@linutronix.de, hpa@zytor.com, julien.thierry@arm.com, will.deacon@arm.com, luto@amacapital.net, mingo@kernel.org, catalin.marinas@arm.com, james.morse@arm.com, valentin.schneider@arm.com, brgerst@gmail.com, jpoimboe@redhat.com, luto@kernel.org, bp@alien8.de, dvlasenk@redhat.com Cc: linux-kernel@vger.kernel.org, dvyukov@google.com, rostedt@goodmis.org Subject: Re: [PATCH 00/20] objtool: UACCESS validation v3 Message-ID: <20190307125526.GB32534@hirez.programming.kicks-ass.net> References: <20190307114511.870090179@infradead.org> <20190307120317.GD32477@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190307120317.GD32477@hirez.programming.kicks-ass.net> 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 01:03:17PM +0100, Peter Zijlstra wrote: > 01c3 20d8: 77 08 ja 20e2 <__do_sys_waitid+0x1cd> taken: randconfig-build/kernel/exit.o: warning: objtool: __do_sys_waitid()+0x1c3: (branch) > ffffffffffffe0f5 alternative("", __stringify(__ASM_STAC), X86_FEATURE_SMAP); > 01c8 20dd: 90 nop > 01c9 20de: 90 nop > 01ca 20df: 90 nop Bye-bye STAC, jumped straight over. > 01cd 20e2: 83 f0 01 xor $0x1,%eax > 01d0 20e5: 48 89 c2 mov %rax,%rdx > 01d3 20e8: 83 e2 01 and $0x1,%edx > 01d6 20eb: 48 83 c2 02 add $0x2,%rdx > 01da 20ef: 48 ff 04 d5 00 00 00 incq 0x0(,%rdx,8) > 01e1 20f6: 00 > 01de 20f3: R_X86_64_32S _ftrace_branch+0x148 > 01e2 20f7: 84 c0 test %al,%al > 01e4 20f9: 75 2d jne 2128 <__do_sys_waitid+0x213> we do not take this branch and fall-through. > ffffffffffffe0eb return -EFAULT; > ffffffffffffe0eb > ffffffffffffe0eb unsafe_put_user(signo, &infop->si_signo, Efault); > 01e6 20fb: 44 89 33 mov %r14d,(%rbx) fault, take exception: randconfig-build/kernel/exit.o: warning: objtool: __do_sys_waitid()+0x1e6: (alt) Relocation section '.rela__ex_table' at offset 0x21568 contains 18 entries: Offset Info Type Sym. Value Sym. Name + Addend 000000000000 000200000002 R_X86_64_PC32 0000000000000000 .text + 20fb 000000000004 000200000002 R_X86_64_PC32 0000000000000000 .text + 2125 > ffffffffffffefe5 Efault: > ffffffffffffe0eb user_access_end(); > 0210 2125: 90 nop > 0211 2126: 90 nop > 0212 2127: 90 nop randconfig-build/kernel/exit.o: warning: objtool: __do_sys_waitid()+0x210: (alt) 000000000034 000200000002 R_X86_64_PC32 0000000000000000 .text + 2125 000000000038 00c800000002 R_X86_64_PC32 0000000000000000 .altinstr_replacement + c 0000000000000000 <.altinstr_replacement>: c: 0f 01 ca clac randconfig-build/kernel/exit.o: warning: objtool: .altinstr_replacement+0xc: redundant UACCESS disable