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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 89D9AC4332B for ; Wed, 3 Mar 2021 18:11:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4259F64EC3 for ; Wed, 3 Mar 2021 18:11:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1386002AbhCCRdV (ORCPT ); Wed, 3 Mar 2021 12:33:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:49474 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241221AbhCCNMZ (ORCPT ); Wed, 3 Mar 2021 08:12:25 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0834A60C3E; Wed, 3 Mar 2021 12:18:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614773912; bh=v3CqCbTv0mkQkZ9Ih1RedXVPZV9P2fo8wFRseCGcHv8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=blDw8YeZouCbRsfc7ZOUXPRTlU59K/tmWQLE8EanPyntbPVhlqDdyM3ZtTCq0d4OG qrod534Ed4NAeIkg6ogDPq5pMCoJR5J3LrAlD8BJmZEugEGc94+PzpbMq5GV+CMQAR MnpIku34NR5dTqmIv6TNWUEC0k1fM3UY4dslGpQ1bg5NZjw0j2VG5a2Bt3Rk9Hs3Vw PvkcyVKZy0KJMX5BwbK4WzsHN8TmKXWDgWdHWg4qZrkvd4UazhLOctL2VCDZNw/Qxs EZoviPLUTogdPA6j3raB605qmkGjGyv1HjuDnmjupQVgvIrnAi3DGuWd+4ZFdH4kUN 83uw+wxaX/AeQ== Date: Wed, 3 Mar 2021 21:18:27 +0900 From: Masami Hiramatsu To: ShaoBo Huang Cc: , , , , , , , , , , , Subject: Re: [PATCH 4.9.y] arm: kprobes: Allow to handle reentered kprobe on single-stepping Message-Id: <20210303211827.eeb89c8a9b140152fbcd997c@kernel.org> In-Reply-To: <20210303071052.33740-1-huangshaobo6@huawei.com> References: <20210303071052.33740-1-huangshaobo6@huawei.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > -- Masami Hiramatsu