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=-14.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 73036C433F5 for ; Tue, 14 Sep 2021 16:04:29 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 2CE2B61151 for ; Tue, 14 Sep 2021 16:04:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 2CE2B61151 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=lK93rNghZYTAwSZyD27yOirUW10ONra+9bzyMacvL1A=; b=ORDMFOsdF+0yM7 4kv8CrqI3eyc1se/keG62VMIMDYL8+w90nFzpNLFFdBBNxxVnQmOF14x5cyuUIHcewnb7UcGpVRNJ FXiDICgbMa4XmD9QQ/05KaKbIdw8mxldp3EQRfzyKBWcaDQAxuRQx+PQgiPRgvhtDN0DEGwiTjar7 LeO5eZjJwZGe3vmsDwNM6DoBkt7WSy5CZ2VXVADLFAvhURZurvNTEEePcMouF746KXhmpqCRp2TbY TIASP9WZ2eY69u59rvGME6THBcmBPZYlC8qKKukAEl6mGyXtO2FHrS4byPEVGFwBHr42I6JR9E56A /wnPe+WghJQcldUa+ztg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mQAtP-006Mkf-Av; Tue, 14 Sep 2021 16:02:43 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mQArp-006Lze-Rk for linux-arm-kernel@lists.infradead.org; Tue, 14 Sep 2021 16:01:07 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CAD22101E; Tue, 14 Sep 2021 09:01:03 -0700 (PDT) Received: from C02TD0UTHF1T.local (unknown [10.57.21.233]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A0A293F5A1; Tue, 14 Sep 2021 09:01:02 -0700 (PDT) Date: Tue, 14 Sep 2021 17:00:56 +0100 From: Mark Rutland To: Amit Daniel Kachhap Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Vincenzo Frascino , Catalin Marinas , Will Deacon Subject: Re: [PATCH] arm64/traps: Avoid unnecessary kernel/user pointer conversion Message-ID: <20210914160056.GA35239@C02TD0UTHF1T.local> References: <20210914152742.27047-1-amit.kachhap@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210914152742.27047-1-amit.kachhap@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210914_090106_012158_30287711 X-CRM114-Status: GOOD ( 19.84 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Sep 14, 2021 at 08:57:42PM +0530, Amit Daniel Kachhap wrote: > Annotating a pointer from kernel to __user and then back again might > confuse sparse. In call_undef_hook() it can be avoided by not using the > intermediate user pointer variable. When you say "might confuse sparse", does it complain today? If so, can you include an example of what goes wrong? > Note: This patch adds no functional changes to code. > > Cc: Catalin Marinas > Cc: Will Deacon > Signed-off-by: Amit Daniel Kachhap > --- > arch/arm64/kernel/traps.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c > index b03e383d944a..357d10a8bbf5 100644 > --- a/arch/arm64/kernel/traps.c > +++ b/arch/arm64/kernel/traps.c > @@ -404,7 +404,8 @@ static int call_undef_hook(struct pt_regs *regs) > > if (!user_mode(regs)) { > __le32 instr_le; > - if (get_kernel_nofault(instr_le, (__force __le32 *)pc)) > + if (get_kernel_nofault(instr_le, > + (__le32 *)instruction_pointer(regs))) Can we make `pc` an unsigned long, instead? It'd be nice to handle all three cases consistently, even if that means adding __force to the two user cases. Thanks, Mark. > goto exit; > instr = le32_to_cpu(instr_le); > } else if (compat_thumb_mode(regs)) { > -- > 2.17.1 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel