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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 1EB9DC43387 for ; Fri, 11 Jan 2019 18:22:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0026A21841 for ; Fri, 11 Jan 2019 18:22:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733032AbfAKSWn (ORCPT ); Fri, 11 Jan 2019 13:22:43 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:33240 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732671AbfAKSWm (ORCPT ); Fri, 11 Jan 2019 13:22:42 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 145BC80D; Fri, 11 Jan 2019 10:22:42 -0800 (PST) Received: from [10.1.196.105] (eglon.cambridge.arm.com [10.1.196.105]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 760CD3F6CF; Fri, 11 Jan 2019 10:22:40 -0800 (PST) Subject: Re: [PATCH 1/3] arm64: kprobes: Move extable address check into arch_prepare_kprobe() To: Masami Hiramatsu Cc: Catalin Marinas , Will Deacon , Pratyush Anand , "David A . Long" , linux-arm-kernel@lists.infradead.org, linux-kernel References: <154502881646.30629.9938335052821665530.stgit@devbox> <154502884653.30629.3172839440883293817.stgit@devbox> <20190108113953.8bc0cc7d196ddba370377217@kernel.org> <20190109110500.b4b5049f4c67dfc85b9ced4e@kernel.org> From: James Morse Message-ID: <92c160a8-7627-0c64-ed73-df616e9c057d@arm.com> Date: Fri, 11 Jan 2019 18:22:38 +0000 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 MIME-Version: 1.0 In-Reply-To: <20190109110500.b4b5049f4c67dfc85b9ced4e@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 09/01/2019 02:05, Masami Hiramatsu wrote: > On Tue, 8 Jan 2019 17:13:36 +0000 > James Morse wrote: >> 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. Thanks, now it all makes sense! Reviewed-by: James Morse Could you include a paragraph like that in the cover-letter or commit-message? The 'fix' in the cover-letter subject had me looking for the bug! Thanks, James