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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 19AE2C433E1 for ; Tue, 25 Aug 2020 13:30:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E72D02074A for ; Tue, 25 Aug 2020 13:30:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="JePRDUdS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726095AbgHYNaU (ORCPT ); Tue, 25 Aug 2020 09:30:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726024AbgHYNaR (ORCPT ); Tue, 25 Aug 2020 09:30:17 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 50170C061574 for ; Tue, 25 Aug 2020 06:30:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=T0iA/ESQ7g89ajHduy7nVinGEeYb5qspM1YNkrQY/OQ=; b=JePRDUdSk6wTLpH+cDjmhVmoCP iKx9/roB2SULZZms3G5d07MEjORCH/osBFueYs1IdIS8T62B3Zb0FV8YZVJPYijn74LljtZAH3Qst jITFluYmF2XPojsZy4VrYPd2cj11vHmyhtHLqW4ZcPZ6LuvAfP2JTGV7FCgM6BJhjzDQ3bq8+LJFX cHvaN8Vanpl7dVO29V3pfVQoaU+vdi5ZvCEIoqMPrgJvagRZaBEG0PGrZtK3+RB1qivIGMl3/4S+t HywWwaisgot7VbZ3rYSPUC7hJemtaoOQ5RL7m+6Sc4bAWrnAOFYOdRT/NC3OlfEWdlUF9YyxXiHLe SpibzOMw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kAZ1b-0001Lp-5c; Tue, 25 Aug 2020 13:30:07 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 40F1A3003D8; Tue, 25 Aug 2020 15:30:05 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 29B3421F9DB48; Tue, 25 Aug 2020 15:30:05 +0200 (CEST) Date: Tue, 25 Aug 2020 15:30:05 +0200 From: peterz@infradead.org To: Masami Hiramatsu Cc: "Eddy_Wu@trendmicro.com" , "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) Message-ID: <20200825133005.GY1362448@hirez.programming.kicks-ass.net> References: <8816bdbbc55c4d2397e0b02aad2825d3@trendmicro.com> <20200825005426.f592075d13be740cb3c9aa77@kernel.org> <7396e7b2079644a6aafd9670a111232b@trendmicro.com> <20200825151538.f856d701a34f4e0561a64932@kernel.org> <20200825120911.GX1362448@hirez.programming.kicks-ass.net> <20200825221555.a2d72c9754284feced6a8536@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200825221555.a2d72c9754284feced6a8536@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 25, 2020 at 10:15:55PM +0900, Masami Hiramatsu wrote: > > damn... one last problem is dangling instances.. so close. > > We can apparently unregister a kretprobe while there's still active > > kretprobe_instance's out referencing it. > > Yeah, kretprobe already provided the per-instance data (as far as > I know, only systemtap depends on it). We need to provide it for > such users. > But if we only have one lock, we can avoid checking NMI because > we can check the recursion with trylock. It is needed only if the > kretprobe uses per-instance data. Or we can just pass a dummy > instance on the stack. I think it is true in general, you can unregister a rp while tasks are preempted. Anyway,. I think I have a solution, just need to talk to paulmck for a bit. > > Ignoring that issue for the moment, the below seems to actually work. > > OK, this looks good to me too. > I'll make a series to rewrite kretprobe based on this patch, OK? Please, I'll send the fix along when I have it.