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=-6.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 3CDE7C433E2 for ; Wed, 2 Sep 2020 13:50:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1787820767 for ; Wed, 2 Sep 2020 13:50:17 +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="MfWWEdwY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727866AbgIBNtx (ORCPT ); Wed, 2 Sep 2020 09:49:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32788 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727024AbgIBNlC (ORCPT ); Wed, 2 Sep 2020 09:41:02 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1789BC06123B for ; Wed, 2 Sep 2020 06:38:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=HLJQCZHx6poAziNUgEdGRzGFUk3q15Hg/3SXsnWe/Zo=; b=MfWWEdwYq0knADT+MsiPZXiJub 7eVu6bk577u/zpj5cOmG3zltjwUbJO183eW3qS0VHaAH5HkC0vDxFLnUisfgBBCpmN1lRZjCgkylB 0NHToSfJNVc+ma2vGWtSQG8BErKFtRC2HeV6kUMl9oc4VXB/zhM2Ufg45Uv2vmheufbXj2olW0cev KVBkNHsNFvhNMLaUXmTR1reyY2UxvP7zScZ9MpYB9D4gmu6szvwkv5rmynLp5j5CBCdXY/nS1JD6R qIDals+GBf7qhGWVxp8BsQioPeFrF8of8qoMsVDU3HYrphlnqSOMUhxvVkxNI0ezXXesXwAsiZbf8 4bTn5PVA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kDSxr-0002dd-EB; Wed, 02 Sep 2020 13:38:15 +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 D3D203062BA; Wed, 2 Sep 2020 15:38:11 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id AE88020104617; Wed, 2 Sep 2020 15:38:11 +0200 (CEST) Message-ID: <20200902133200.666781610@infradead.org> User-Agent: quilt/0.66 Date: Wed, 02 Sep 2020 15:25:50 +0200 From: Peter Zijlstra To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, Kyle Huey , Alexandre Chartre , Robert O'Callahan , "Paul E. McKenney" , Frederic Weisbecker , Paolo Bonzini , Sean Christopherson , Masami Hiramatsu , Petr Mladek , Steven Rostedt , Joel Fernandes , Boris Ostrovsky , Juergen Gross , Brian Gerst , Andy Lutomirski , Josh Poimboeuf , Daniel Thompson , Peter Zijlstra , Andrew Cooper Subject: [PATCH 01/13] x86/entry: Fix AC assertion References: <20200902132549.496605622@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra The WARN added in commit 3c73b81a9164 ("x86/entry, selftests: Further improve user entry sanity checks") unconditionally triggers on my IVB machine because it does not support SMAP. For !SMAP hardware we patch out CLAC/STAC instructions and thus if userspace sets AC, we'll still have it set after entry. Fixes: 3c73b81a9164 ("x86/entry, selftests: Further improve user entry sanity checks") Signed-off-by: Peter Zijlstra (Intel) Acked-by: Andy Lutomirski --- arch/x86/include/asm/entry-common.h | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/arch/x86/include/asm/entry-common.h +++ b/arch/x86/include/asm/entry-common.h @@ -18,8 +18,16 @@ static __always_inline void arch_check_u * state, not the interrupt state as imagined by Xen. */ unsigned long flags = native_save_fl(); - WARN_ON_ONCE(flags & (X86_EFLAGS_AC | X86_EFLAGS_DF | - X86_EFLAGS_NT)); + unsigned long mask = X86_EFLAGS_DF | X86_EFLAGS_NT; + + /* + * For !SMAP hardware we patch out CLAC on entry. + */ + if (boot_cpu_has(X86_FEATURE_SMAP) || + (IS_ENABLED(CONFIG_64_BIT) && boot_cpu_has(X86_FEATURE_XENPV))) + mask |= X86_EFLAGS_AC; + + WARN_ON_ONCE(flags & mask); /* We think we came from user mode. Make sure pt_regs agrees. */ WARN_ON_ONCE(!user_mode(regs));