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=-5.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 19349C43387 for ; Wed, 9 Jan 2019 02:05:15 +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 DDF6E206BB for ; Wed, 9 Jan 2019 02:05:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="nq0M0Oua"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="2AigcZnM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DDF6E206BB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Mime-Version:References:In-Reply-To: Message-Id:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=FSBH7KnqGv9+P51xLFNGO4TQMUrQhJOR9SIwP96T3Zo=; b=nq0M0Oua0yB9x4 cnr1AJxJ1SrIIULTEqPwY09FeeV0+j8mflvfbf4TOrj6MDf75iK7fbhcNqi9RgLzt+5bObzHtdE5c sZkK8aTrx/B1Muvz5465DNY4RiFIxtftrIc3GTimu8KuZxyO6chCqonlGCN0GAr0P3l3cDh5yYi2/ hsNncoPOt07lNB/1sflYqQ4QTQ7QmlPNwh0YCr3UbBAZkb6LC5QSYw0/HMkfb/h8wEI2CdH6aoTVq 9miZzY1PmqATsCDEuIAxOljd3KW233jV3WeRrg+vZ7+LOQAUccbaKTm8Et7uM+Zn1eX33aDL5sy8c 7DlF0TZKRzKBnIGwQDVw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gh3F1-0006Uz-3q; Wed, 09 Jan 2019 02:05:11 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gh3Ex-00069z-HB for linux-arm-kernel@lists.infradead.org; Wed, 09 Jan 2019 02:05:09 +0000 Received: from devnote (p103030-mobac01.tokyo.ocn.ne.jp [153.233.94.30]) (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 21085206BB; Wed, 9 Jan 2019 02:05:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546999506; bh=Ickqk2IZkIG8p04SgQek3hIsU1ZxkvWNSEhuLaJp8Mw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=2AigcZnMw1WQlONJhKEoRIJcREnBHjp7eqluXdmyCKIr5U8I9VVFR0H+7GAI1ciyO ciZqVwHQOi0ZHkjJ5/tblVIwzgGKd4/ZIRQ3rFcBsXeJgO9KBL2XUdsEDRFA4lfVZM keNRAWE9I4zF9m49i5lO0uXSP3vB0vU1wVbZZVWA= Date: Wed, 9 Jan 2019 11:05:00 +0900 From: Masami Hiramatsu To: James Morse Subject: Re: [PATCH 1/3] arm64: kprobes: Move extable address check into arch_prepare_kprobe() Message-Id: <20190109110500.b4b5049f4c67dfc85b9ced4e@kernel.org> In-Reply-To: References: <154502881646.30629.9938335052821665530.stgit@devbox> <154502884653.30629.3172839440883293817.stgit@devbox> <20190108113953.8bc0cc7d196ddba370377217@kernel.org> X-Mailer: Sylpheed 3.5.0 (GTK+ 2.24.30; x86_64-pc-linux-gnu) Mime-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190108_180507_608466_74C15339 X-CRM114-Status: GOOD ( 21.99 ) 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: Pratyush Anand , Catalin Marinas , Will Deacon , linux-kernel , "David A . Long" , linux-arm-kernel@lists.infradead.org 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 Hi James, On Tue, 8 Jan 2019 17:13:36 +0000 James Morse wrote: > Hi! > > On 08/01/2019 02:39, Masami Hiramatsu wrote: > > On Thu, 3 Jan 2019 17:05:18 +0000 > > James Morse wrote: > >> On 17/12/2018 06:40, Masami Hiramatsu wrote: > >>> Move extable address check into arch_prepare_kprobe() from > >>> arch_within_kprobe_blacklist(). > >> > >> I'm trying to work out the pattern for what should go in the blacklist, and what > >> should be rejected by the arch code. > >> > >> It seems address-ranges should be blacklisted as the contents don't matter. > >> easy-example: the idmap text. > > > > Yes, more precisely, the code smaller than a function (symbol), it must be > > rejected by arch_prepare_kprobe(), since blacklist is poplated based on > > kallsyms. > > Ah, okay, so the pattern is the blacklist should only be for whole symbols, > (which explains why its usually based on sections). Correct. Actually, the blacklist is generated based on the symbol info from symbol address. > I see kprobe_add_ksym_blacklist() would go wrong if you give it something like: > platform_drv_probe+0x50/0xb0, as it will log platform_drv_probe+0x50 as the > start_addr and platform_drv_probe+0x50+0xb0 as the end. Yes, it expects given address is the entry of a symbol. > > But how does anything from the arch code's blacklist get into the > kprobe_blacklist list? It should be done via arch_populate_kprobe_blacklist(). > > We don't have an arch_populate_kprobe_blacklist(), so rely on > within_kprobe_blacklist() calling arch_within_kprobe_blacklist() with the > address, as well as walking kprobe_blacklist. > > Is this cleanup ahead of a series that does away with > arch_within_kprobe_blacklist() so that debugfs list is always complete? Right, after this cleanup, I will send arch_populate_kprobe_blacklist() patch for arm64 and others. My plan is to move all arch_within_kprobe_blacklist() to arch_populate_kprobe_blacklist() so that user can get more precise blacklist via debugfs. > > As I pointed, the exception_table contains some range of code which inside > > functions, must be smaller than function. > > Since those instructions are expected to cause exception (that is main reason > > why it can not be probed on arm64), I thought such situation was similar to > > the limitation of instruction. > > > > So I think below will be better. > > ---- > > Please do not blacklisting instructions on exception_table, > > since those are smaller than one function. > > ---- > > I keep tripping over this because the exception_table lists addresses that are > allowed to fault. Nothing looks at the instruction, and we happily kprobe the > same instruction elsewhere. Thanks! > > (based on my assumptions about where you are going next!,), How about: > | The blacklist is exposed via debugfs as a list of symbols. extable entries are > | smaller, so must be filtered out by arch_prepare_kprobe(). This looks much better for me too :) Should I resend with the description? Thank you! > > (only we currently have more than one blacklist...) > > > Thanks, > > James -- Masami Hiramatsu _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel