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=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS autolearn=no 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 5C44DC433E1 for ; Wed, 26 Aug 2020 09:06:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2921A2075E for ; Wed, 26 Aug 2020 09:06:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598432813; bh=KLBWFTqIGdn6a1M534qrDK+NOnMbELdfxkrei37Ruxc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=J4ddUmBovPAEUF1xH2l6yCK361480hir52HWVdBenxIxFCyBwBObvr+LZjq1Neog+ vJon+U2Ya2Lp9vx7mdciRtZ9RjQ8+ejF4jrwBapNIyA6B7UkSNcCwIasUCJuGbMdt3 4CvGIEukOT5jV+Pibj5NNLsjahZ4p8v0li7CVr7o= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727971AbgHZJGv (ORCPT ); Wed, 26 Aug 2020 05:06:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:48168 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727906AbgHZJGt (ORCPT ); Wed, 26 Aug 2020 05:06:49 -0400 Received: from devnote2 (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9AE00206FA; Wed, 26 Aug 2020 09:06:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598432809; bh=KLBWFTqIGdn6a1M534qrDK+NOnMbELdfxkrei37Ruxc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=M1et6vgEx9Tml0fXkvzI0PV1xJGB+sI9E1iDWewTwheg0Naz9xHddgbU8Bahl227c qzuIqMAZc0DvN5exenz9ltXM3eDLHE9Ucjsb0lBi0GvkT+lxQ85HAYpYERDuJw5gF5 jI7QkkVILP6yVTZFi371oaQSzhDe3IoNrm/vwJI8= Date: Wed, 26 Aug 2020 18:06:45 +0900 From: Masami Hiramatsu To: Masami Hiramatsu Cc: "Eddy_Wu@trendmicro.com" , "peterz@infradead.org" , "linux-kernel@vger.kernel.org" , "x86@kernel.org" Subject: Re: x86/kprobes: kretprobe fails to triggered if kprobe at function entry is not optimized (trigger by int3 breakpoint) Message-Id: <20200826180645.9b609fc05df2a149564df1b8@kernel.org> In-Reply-To: <20200826172239.ff175be78ee5f3a4380579c3@kernel.org> References: <8816bdbbc55c4d2397e0b02aad2825d3@trendmicro.com> <20200825005426.f592075d13be740cb3c9aa77@kernel.org> <7396e7b2079644a6aafd9670a111232b@trendmicro.com> <20200825151538.f856d701a34f4e0561a64932@kernel.org> <20200825120911.GX1362448@hirez.programming.kicks-ass.net> <20200826172239.ff175be78ee5f3a4380579c3@kernel.org> 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 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 26 Aug 2020 17:22:39 +0900 Masami Hiramatsu wrote: > On Wed, 26 Aug 2020 07:07:09 +0000 > "Eddy_Wu@trendmicro.com" wrote: > > > > > > -----Original Message----- > > > From: peterz@infradead.org > > > Sent: Tuesday, August 25, 2020 8:09 PM > > > To: Masami Hiramatsu > > > Cc: Eddy Wu (RD-TW) ; linux-kernel@vger.kernel.org; x86@kernel.org; David S. Miller > > > > > > Subject: Re: x86/kprobes: kretprobe fails to triggered if kprobe at function entry is not optimized (trigger by int3 breakpoint) > > > > > > Surely we can do a lockless list for this. We have llist_add() and > > > llist_del_first() to make a lockless LIFO/stack. > > > > > > > llist operations require atomic cmpxchg, for some arch doesn't have CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG, in_nmi() check might still needed. > > (HAVE_KRETPROBES && !CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG): arc, arm, csky, mips > > Good catch. In those cases, we can add in_nmi() check at arch dependent code. Oops, in_nmi() check is needed in pre_kretprobe_handler() which has no arch dependent code. Hmm, so we still need an weak function to check it... Thanks, -- Masami Hiramatsu