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=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 AE1D2C3A5A4 for ; Fri, 30 Aug 2019 13:35:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 719FD21897 for ; Fri, 30 Aug 2019 13:35:57 +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" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 719FD21897 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F3CD46B0006; Fri, 30 Aug 2019 09:35:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EECC36B0008; Fri, 30 Aug 2019 09:35:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E020B6B000A; Fri, 30 Aug 2019 09:35:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0054.hostedemail.com [216.40.44.54]) by kanga.kvack.org (Postfix) with ESMTP id BA7236B0006 for ; Fri, 30 Aug 2019 09:35:56 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 666DD181AC9AE for ; Fri, 30 Aug 2019 13:35:56 +0000 (UTC) X-FDA: 75879192312.10.beam16_168e80e537d0c X-HE-Tag: beam16_168e80e537d0c X-Filterd-Recvd-Size: 5396 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) by imf30.hostedemail.com (Postfix) with ESMTP for ; Fri, 30 Aug 2019 13:35:54 +0000 (UTC) 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) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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