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=-8.8 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,URIBL_BLOCKED,USER_AGENT_NEOMUTT 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 D6EF6C04AB6 for ; Tue, 28 May 2019 12:42:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB74620883 for ; Tue, 28 May 2019 12:42:25 +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="HPRJ9AXd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727447AbfE1MmY (ORCPT ); Tue, 28 May 2019 08:42:24 -0400 Received: from pandora.armlinux.org.uk ([78.32.30.218]:37976 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727390AbfE1MmX (ORCPT ); Tue, 28 May 2019 08:42:23 -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=t2vArhK5ONSzG4f61utNPX6iuQEVIA/xkviTlXVlEb4=; b=HPRJ9AXdPxXH93KtZWMlngs4d oLca7XsLgMK+6r6FdA4ZxY5y/aTFakuSI1ts6DG7/vtK92LYzhXJvGTVO1RTDATctncupVy4biIGM c14v4cUXQ9R9xaGfMz+wXoROvs7/teJ1apRU5hP1s+MEKHvIMeNVduA7NPxAlFKijYKStRXmdRUaB HycwgL/lBtOVl4LbgU7XZx0Kwp/EDpL0I5l+TXVTmZz85KEH+rDWSJTfWxOr+4hX19oY0ABEq0P54 XthKetauAq/9eWp9+emsOoOJ0Q8T2I03rK3gXz4jkv7PpgO8rwQeZ6OGYOHz8pYbzhnd70glyCVbU n/lH3o41A==; Received: from shell.armlinux.org.uk ([2001:4d48:ad52:3201:5054:ff:fe00:4ec]:56030) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1hVbQS-0005lo-AK; Tue, 28 May 2019 13:41:56 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.89) (envelope-from ) id 1hVbQO-0003cr-Ip; Tue, 28 May 2019 13:41:52 +0100 Date: Tue, 28 May 2019 13:41:52 +0100 From: Russell King - ARM Linux admin To: Young Xiao <92siuyang@gmail.com> Cc: will.deacon@arm.com, mark.rutland@arm.com, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org, peterz@infradead.org, kan.liang@linux.intel.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] perf: Fix oops when kthread execs user process Message-ID: <20190528124152.z76z7ar62hklz7tk@shell.armlinux.org.uk> References: <1559046689-24091-1-git-send-email-92siuyang@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1559046689-24091-1-git-send-email-92siuyang@gmail.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 28, 2019 at 08:31:29PM +0800, Young Xiao wrote: > When a kthread calls call_usermodehelper() the steps are: > 1. allocate current->mm > 2. load_elf_binary() > 3. populate current->thread.regs > > While doing this, interrupts are not disabled. If there is a perf > interrupt in the middle of this process (i.e. step 1 has completed > but not yet reached to step 3) and if perf tries to read userspace > regs, kernel oops. > > Fix it by setting abi to PERF_SAMPLE_REGS_ABI_NONE when userspace > pt_regs are not set. > > See commit bf05fc25f268 ("powerpc/perf: Fix oops when kthread execs > user process") for details. > > Signed-off-by: Young Xiao <92siuyang@gmail.com> > --- > arch/arm/kernel/perf_regs.c | 3 ++- > arch/arm64/kernel/perf_regs.c | 3 ++- > arch/x86/kernel/perf_regs.c | 3 ++- > 3 files changed, 6 insertions(+), 3 deletions(-) > > diff --git a/arch/arm/kernel/perf_regs.c b/arch/arm/kernel/perf_regs.c > index 05fe92a..78ee29a 100644 > --- a/arch/arm/kernel/perf_regs.c > +++ b/arch/arm/kernel/perf_regs.c > @@ -36,5 +36,6 @@ void perf_get_regs_user(struct perf_regs *regs_user, > struct pt_regs *regs_user_copy) > { > regs_user->regs = task_pt_regs(current); > - regs_user->abi = perf_reg_abi(current); > + regs_user->abi = (regs_user->regs) ? perf_reg_abi(current) : > + PERF_SAMPLE_REGS_ABI_NONE; I'd prefer it if we didn't introduce unnecessary parens - what function do the parens around "regs_user->regs" serve? -- 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=-9.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_NEOMUTT 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 A80C4C04AB6 for ; Tue, 28 May 2019 12:42:29 +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 805D820883 for ; 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bh=t2vArhK5ONSzG4f61utNPX6iuQEVIA/xkviTlXVlEb4=; b=HPRJ9AXdPxXH93KtZWMlngs4d oLca7XsLgMK+6r6FdA4ZxY5y/aTFakuSI1ts6DG7/vtK92LYzhXJvGTVO1RTDATctncupVy4biIGM c14v4cUXQ9R9xaGfMz+wXoROvs7/teJ1apRU5hP1s+MEKHvIMeNVduA7NPxAlFKijYKStRXmdRUaB HycwgL/lBtOVl4LbgU7XZx0Kwp/EDpL0I5l+TXVTmZz85KEH+rDWSJTfWxOr+4hX19oY0ABEq0P54 XthKetauAq/9eWp9+emsOoOJ0Q8T2I03rK3gXz4jkv7PpgO8rwQeZ6OGYOHz8pYbzhnd70glyCVbU n/lH3o41A==; Received: from shell.armlinux.org.uk ([2001:4d48:ad52:3201:5054:ff:fe00:4ec]:56030) by pandora.armlinux.org.uk with esmtpsa (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1hVbQS-0005lo-AK; Tue, 28 May 2019 13:41:56 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.89) (envelope-from ) id 1hVbQO-0003cr-Ip; Tue, 28 May 2019 13:41:52 +0100 Date: Tue, 28 May 2019 13:41:52 +0100 From: Russell King - ARM Linux admin To: Young Xiao <92siuyang@gmail.com> Subject: Re: [PATCH] perf: Fix oops when kthread execs user process Message-ID: <20190528124152.z76z7ar62hklz7tk@shell.armlinux.org.uk> References: <1559046689-24091-1-git-send-email-92siuyang@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1559046689-24091-1-git-send-email-92siuyang@gmail.com> User-Agent: NeoMutt/20170113 (1.7.2) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190528_054220_028519_16EC969D X-CRM114-Status: GOOD ( 15.69 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, peterz@infradead.org, x86@kernel.org, will.deacon@arm.com, linux-kernel@vger.kernel.org, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, linux-arm-kernel@lists.infradead.org, kan.liang@linux.intel.com 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 Tue, May 28, 2019 at 08:31:29PM +0800, Young Xiao wrote: > When a kthread calls call_usermodehelper() the steps are: > 1. allocate current->mm > 2. load_elf_binary() > 3. populate current->thread.regs > > While doing this, interrupts are not disabled. If there is a perf > interrupt in the middle of this process (i.e. step 1 has completed > but not yet reached to step 3) and if perf tries to read userspace > regs, kernel oops. > > Fix it by setting abi to PERF_SAMPLE_REGS_ABI_NONE when userspace > pt_regs are not set. > > See commit bf05fc25f268 ("powerpc/perf: Fix oops when kthread execs > user process") for details. > > Signed-off-by: Young Xiao <92siuyang@gmail.com> > --- > arch/arm/kernel/perf_regs.c | 3 ++- > arch/arm64/kernel/perf_regs.c | 3 ++- > arch/x86/kernel/perf_regs.c | 3 ++- > 3 files changed, 6 insertions(+), 3 deletions(-) > > diff --git a/arch/arm/kernel/perf_regs.c b/arch/arm/kernel/perf_regs.c > index 05fe92a..78ee29a 100644 > --- a/arch/arm/kernel/perf_regs.c > +++ b/arch/arm/kernel/perf_regs.c > @@ -36,5 +36,6 @@ void perf_get_regs_user(struct perf_regs *regs_user, > struct pt_regs *regs_user_copy) > { > regs_user->regs = task_pt_regs(current); > - regs_user->abi = perf_reg_abi(current); > + regs_user->abi = (regs_user->regs) ? perf_reg_abi(current) : > + PERF_SAMPLE_REGS_ABI_NONE; I'd prefer it if we didn't introduce unnecessary parens - what function do the parens around "regs_user->regs" serve? -- 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