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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 74EFAC4332D for ; Thu, 4 Mar 2021 13:29:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4979A64F3F for ; Thu, 4 Mar 2021 13:29:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241336AbhCDN3Y (ORCPT ); Thu, 4 Mar 2021 08:29:24 -0500 Received: from mail.kernel.org ([198.145.29.99]:47476 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241322AbhCDN3U (ORCPT ); Thu, 4 Mar 2021 08:29:20 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 168ED64F09; Thu, 4 Mar 2021 13:28:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614864519; bh=PlxQOKZoaaVMaVivmUaFdQ1jJjo4ppMmxLiHNzuyqu0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ghGFDTbUt5CZzt6wrynBaP2psr88fm7pz6jNYLhlPl6i88exw/WZZAUPflRR6fDxM jdcpo20Bwp26NoJjB1DITpcwIPMCzXh1eYFWfsYhiSOn/t/PAk6K6/Kv5XdtMwVlJB 1lzatQDCW9/DjNbDcuGRhOioGMp+orSUMCK75cC4= Date: Thu, 4 Mar 2021 14:28:37 +0100 From: Greg KH To: Masami Hiramatsu Cc: ShaoBo Huang , linux@armlinux.org.uk, tixy@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, young.liuyang@huawei.com, zengweilin@huawei.com, nixiaoming@huawei.com, chenzefeng2@huawei.com, liucheng32@huawei.com, kepler.chenxin@huawei.com, xiaoqian9@huawei.com Subject: Re: [PATCH 4.9.y] arm: kprobes: Allow to handle reentered kprobe on single-stepping Message-ID: References: <20210303071052.33740-1-huangshaobo6@huawei.com> <20210303211827.eeb89c8a9b140152fbcd997c@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210303211827.eeb89c8a9b140152fbcd997c@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 03, 2021 at 09:18:27PM +0900, Masami Hiramatsu wrote: > Hi ShaoBo, > > Thanks for backporting and real bug report! > > On Wed, 3 Mar 2021 15:10:52 +0800 > ShaoBo Huang wrote: > > > From: Masami Hiramatsu > > > > commit f3fbd7ec62dec1528fb8044034e2885f2b257941 upstream > > > > This is arm port of commit 6a5022a56ac3 ("kprobes/x86: Allow to > > handle reentered kprobe on single-stepping") > > > > Since the FIQ handlers can interrupt in the single stepping > > (or preparing the single stepping, do_debug etc.), we should > > consider a kprobe is hit in the NMI handler. Even in that > > case, the kprobe is allowed to be reentered as same as the > > kprobes hit in kprobe handlers > > (KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE). > > > > The real issue will happen when a kprobe hit while another > > reentered kprobe is processing (KPROBE_REENTER), because > > we already consumed a saved-area for the previous kprobe. > > > > Signed-off-by: Masami Hiramatsu > > Signed-off-by: Jon Medhurst > > Fixes: 24ba613c9d6c ("ARM kprobes: core code") > > Cc: stable@vger.kernel.org #v2.6.25~v4.11 > > Signed-off-by: huangshaobo > > --- > > arch/arm/probes/kprobes/core.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c > > index 3eb018fa1a1f..c3362ddd6c4c 100644 > > --- a/arch/arm/probes/kprobes/core.c > > +++ b/arch/arm/probes/kprobes/core.c > > @@ -270,6 +270,7 @@ void __kprobes kprobe_handler(struct pt_regs *regs) > > switch (kcb->kprobe_status) { > > case KPROBE_HIT_ACTIVE: > > case KPROBE_HIT_SSDONE: > > + case KPROBE_HIT_SS: > > /* A pre- or post-handler probe got us here. */ > > kprobes_inc_nmissed_count(p); > > save_previous_kprobe(kcb); > > @@ -278,6 +279,11 @@ void __kprobes kprobe_handler(struct pt_regs *regs) > > singlestep(p, regs, kcb); > > restore_previous_kprobe(kcb); > > break; > > + case KPROBE_REENTER: > > + /* A nested probe was hit in FIQ, it is a BUG */ > > + pr_warn("Unrecoverable kprobe detected at %p.\n", > > + p->addr); > > + /* fall through */ > > default: > > /* impossible cases */ > > BUG(); > > -- > > 2.12.3 > > Also queued up to 4.4.y as well. thanks, greg k-h