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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 87859C3A5A9 for ; Mon, 4 May 2020 13:20:27 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5BA802073B for ; Mon, 4 May 2020 13:20:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5BA802073B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jVb0z-00054e-DL; Mon, 04 May 2020 13:20:09 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1jVb0y-00054Z-FU for xen-devel@lists.xenproject.org; Mon, 04 May 2020 13:20:08 +0000 X-Inumbo-ID: f7bf6654-8e09-11ea-9d1f-12813bfff9fa Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id f7bf6654-8e09-11ea-9d1f-12813bfff9fa; Mon, 04 May 2020 13:20:05 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 33593AEA1; Mon, 4 May 2020 13:20:06 +0000 (UTC) Subject: Re: [PATCH 03/16] x86/traps: Factor out exception_fixup() and make printing consistent To: Andrew Cooper References: <20200501225838.9866-1-andrew.cooper3@citrix.com> <20200501225838.9866-4-andrew.cooper3@citrix.com> From: Jan Beulich Message-ID: Date: Mon, 4 May 2020 15:20:03 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200501225838.9866-4-andrew.cooper3@citrix.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Xen-devel , Wei Liu , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On 02.05.2020 00:58, Andrew Cooper wrote: > --- a/xen/arch/x86/traps.c > +++ b/xen/arch/x86/traps.c > @@ -774,10 +774,27 @@ static void do_reserved_trap(struct cpu_user_regs *regs) > trapnr, vec_name(trapnr), regs->error_code); > } > > +static bool exception_fixup(struct cpu_user_regs *regs, bool print) > +{ > + unsigned long fixup = search_exception_table(regs); > + > + if ( unlikely(fixup == 0) ) > + return false; > + > + /* Can currently be triggered by guests. Make sure we ratelimit. */ > + if ( IS_ENABLED(CONFIG_DEBUG) && print ) I didn't think we consider dprintk()-s a possible security issue. Why would we consider so a printk() hidden behind IS_ENABLED(CONFIG_DEBUG)? IOW I think one of XENLOG_GUEST and IS_ENABLED(CONFIG_DEBUG) wants dropping. > @@ -1466,12 +1468,11 @@ void do_page_fault(struct cpu_user_regs *regs) > if ( pf_type != real_fault ) > return; > > - if ( likely((fixup = search_exception_table(regs)) != 0) ) > + if ( likely(exception_fixup(regs, false)) ) > { > perfc_incr(copy_user_faults); > if ( unlikely(regs->error_code & PFEC_reserved_bit) ) > reserved_bit_page_fault(addr, regs); > - regs->rip = fixup; I'm afraid this modification can't validly be pulled ahead - show_execution_state(), as called from reserved_bit_page_fault(), wants to / should print the original RIP, not the fixed up one. Jan