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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 C24A8C3A5A4 for ; Fri, 30 Aug 2019 13:35:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6F7B221897 for ; Fri, 30 Aug 2019 13:35:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="X4PXDlxJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727976AbfH3Nfw (ORCPT ); Fri, 30 Aug 2019 09:35:52 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:34632 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727135AbfH3Nfw (ORCPT ); Fri, 30 Aug 2019 09:35:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: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=cX5HAPQ/pGMAWfMOWWax1diaBYat5jfFHPLeFudRYV0=; b=X4PXDlxJk6XPR03/tA1Mmat89 OfVyp7FrasZ+Qk7+5Z8u6qXX2PI2/X1pZpstwrBjdGaTixrEdRhSvmtsd+zwZ0BYoXFpLbCUXQQNv aW3KWuf6Ep+uGE61r17wYLEA2GrUAlPt8vznDSF7SVgWYOjmU5KZyXoW//REk0/AeCtY6pg2JnZ0U Xfs38hH9Gx3tH9Hs6YEVHq9vfaTBmNsFlh1xt6WBe81h1ku1XiTorCAbuIMRiyNdWQ5swTqFTUAyh 0wi0BAai94HjcnaoOBcfliJLqodqytm6S2nvn0jckR12gFgD8UW2rfsQS/WR4h9Eah/yKtnJCCGyD X579Lc9Jg==; Received: from shell.armlinux.org.uk ([2001:4d48:ad52:3201:5054:ff:fe00:4ec]:56022) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1i3h3m-00075L-CF; Fri, 30 Aug 2019 14:35:26 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1i3h3i-0000A4-59; Fri, 30 Aug 2019 14:35:22 +0100 Date: Fri, 30 Aug 2019 14:35:22 +0100 From: Russell King - ARM Linux admin To: Jing Xiangfeng Cc: ebiederm@xmission.com, kstewart@linuxfoundation.org, gregkh@linuxfoundation.org, gustavo@embeddedor.com, bhelgaas@google.com, tglx@linutronix.de, sakari.ailus@linux.intel.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] arm: fix page faults in do_alignment Message-ID: <20190830133522.GZ13294@shell.armlinux.org.uk> References: <1567171877-101949-1-git-send-email-jingxiangfeng@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1567171877-101949-1-git-send-email-jingxiangfeng@huawei.com> 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 Fri, Aug 30, 2019 at 09:31:17PM +0800, Jing Xiangfeng wrote: > The function do_alignment can handle misaligned address for user and > kernel space. If it is a userspace access, do_alignment may fail on > a low-memory situation, because page faults are disabled in > probe_kernel_address. > > Fix this by using __copy_from_user stead of probe_kernel_address. > > Fixes: b255188 ("ARM: fix scheduling while atomic warning in alignment handling code") > Signed-off-by: Jing Xiangfeng NAK. The "scheduling while atomic warning in alignment handling code" is caused by fixing up the page fault while trying to handle the mis-alignment fault generated from an instruction in atomic context. Your patch re-introduces that bug. > --- > arch/arm/mm/alignment.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c > index 04b3643..2ccabd3 100644 > --- a/arch/arm/mm/alignment.c > +++ b/arch/arm/mm/alignment.c > @@ -774,6 +774,7 @@ static ssize_t alignment_proc_write(struct file *file, const char __user *buffer > unsigned long instr = 0, instrptr; > int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs); > unsigned int type; > + mm_segment_t fs; > unsigned int fault; > u16 tinstr = 0; > int isize = 4; > @@ -784,16 +785,22 @@ static ssize_t alignment_proc_write(struct file *file, const char __user *buffer > > instrptr = instruction_pointer(regs); > > + fs = get_fs(); > + set_fs(KERNEL_DS); > if (thumb_mode(regs)) { > u16 *ptr = (u16 *)(instrptr & ~1); > - fault = probe_kernel_address(ptr, tinstr); > + fault = __copy_from_user(tinstr, > + (__force const void __user *)ptr, > + sizeof(tinstr)); > tinstr = __mem_to_opcode_thumb16(tinstr); > if (!fault) { > if (cpu_architecture() >= CPU_ARCH_ARMv7 && > IS_T32(tinstr)) { > /* Thumb-2 32-bit */ > u16 tinst2 = 0; > - fault = probe_kernel_address(ptr + 1, tinst2); > + fault = __copy_from_user(tinst2, > + (__force const void __user *)(ptr+1), > + sizeof(tinst2)); > tinst2 = __mem_to_opcode_thumb16(tinst2); > instr = __opcode_thumb32_compose(tinstr, tinst2); > thumb2_32b = 1; > @@ -803,10 +810,13 @@ static ssize_t alignment_proc_write(struct file *file, const char __user *buffer > } > } > } else { > - fault = probe_kernel_address((void *)instrptr, instr); > + fault = __copy_from_user(instr, > + (__force const void __user *)instrptr, > + sizeof(instr)); > instr = __mem_to_opcode_arm(instr); > } > > + set_fs(fs); > if (fault) { > type = TYPE_FAULT; > goto bad_or_fault; > -- > 1.8.3.1 > > -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up 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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 CB5E1C3A5A4 for ; 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Fri, 30 Aug 2019 14:35:26 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1i3h3i-0000A4-59; Fri, 30 Aug 2019 14:35:22 +0100 Date: Fri, 30 Aug 2019 14:35:22 +0100 From: Russell King - ARM Linux admin To: Jing Xiangfeng Subject: Re: [PATCH] arm: fix page faults in do_alignment Message-ID: <20190830133522.GZ13294@shell.armlinux.org.uk> References: <1567171877-101949-1-git-send-email-jingxiangfeng@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1567171877-101949-1-git-send-email-jingxiangfeng@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190830_063553_369279_78576170 X-CRM114-Status: GOOD ( 17.28 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kstewart@linuxfoundation.org, gustavo@embeddedor.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ebiederm@xmission.com, sakari.ailus@linux.intel.com, bhelgaas@google.com, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Aug 30, 2019 at 09:31:17PM +0800, Jing Xiangfeng wrote: > The function do_alignment can handle misaligned address for user and > kernel space. If it is a userspace access, do_alignment may fail on > a low-memory situation, because page faults are disabled in > probe_kernel_address. > > Fix this by using __copy_from_user stead of probe_kernel_address. > > Fixes: b255188 ("ARM: fix scheduling while atomic warning in alignment handling code") > Signed-off-by: Jing Xiangfeng NAK. The "scheduling while atomic warning in alignment handling code" is caused by fixing up the page fault while trying to handle the mis-alignment fault generated from an instruction in atomic context. Your patch re-introduces that bug. > --- > arch/arm/mm/alignment.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c > index 04b3643..2ccabd3 100644 > --- a/arch/arm/mm/alignment.c > +++ b/arch/arm/mm/alignment.c > @@ -774,6 +774,7 @@ static ssize_t alignment_proc_write(struct file *file, const char __user *buffer > unsigned long instr = 0, instrptr; > int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs); > unsigned int type; > + mm_segment_t fs; > unsigned int fault; > u16 tinstr = 0; > int isize = 4; > @@ -784,16 +785,22 @@ static ssize_t alignment_proc_write(struct file *file, const char __user *buffer > > instrptr = instruction_pointer(regs); > > + fs = get_fs(); > + set_fs(KERNEL_DS); > if (thumb_mode(regs)) { > u16 *ptr = (u16 *)(instrptr & ~1); > - fault = probe_kernel_address(ptr, tinstr); > + fault = __copy_from_user(tinstr, > + (__force const void __user *)ptr, > + sizeof(tinstr)); > tinstr = __mem_to_opcode_thumb16(tinstr); > if (!fault) { > if (cpu_architecture() >= CPU_ARCH_ARMv7 && > IS_T32(tinstr)) { > /* Thumb-2 32-bit */ > u16 tinst2 = 0; > - fault = probe_kernel_address(ptr + 1, tinst2); > + fault = __copy_from_user(tinst2, > + (__force const void __user *)(ptr+1), > + sizeof(tinst2)); > tinst2 = __mem_to_opcode_thumb16(tinst2); > instr = __opcode_thumb32_compose(tinstr, tinst2); > thumb2_32b = 1; > @@ -803,10 +810,13 @@ static ssize_t alignment_proc_write(struct file *file, const char __user *buffer > } > } > } else { > - fault = probe_kernel_address((void *)instrptr, instr); > + fault = __copy_from_user(instr, > + (__force const void __user *)instrptr, > + sizeof(instr)); > instr = __mem_to_opcode_arm(instr); > } > > + set_fs(fs); > if (fault) { > type = TYPE_FAULT; > goto bad_or_fault; > -- > 1.8.3.1 > > -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel