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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS 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 D1956C43387 for ; Thu, 3 Jan 2019 17:05:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F55D2070D for ; Thu, 3 Jan 2019 17:05:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732494AbfACRFW (ORCPT ); Thu, 3 Jan 2019 12:05:22 -0500 Received: from foss.arm.com ([217.140.101.70]:53250 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730870AbfACRFW (ORCPT ); Thu, 3 Jan 2019 12:05:22 -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 A5A8615AD; Thu, 3 Jan 2019 09:05:21 -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 6B8AB3F5D4; Thu, 3 Jan 2019 09:05:20 -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> From: James Morse Message-ID: Date: Thu, 3 Jan 2019 17:05:18 +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: <154502884653.30629.3172839440883293817.stgit@devbox> 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 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. The arch code should also reject instructions that can't be probed from arch_prepare_kprobe(). easy-example: exclusive load or store. > Please do not blacklisting instructions on exception_table, > since it is a kind of architectural unsupported instruction. This doesn't fit the pattern, ... what should it be? The instructions in the exception_table don't matter, its the address that indicates there is a fixup for page-faults that occur here. We don't need to look at the instruction to determine this, why can't we treated these as a blacklisted range? Thanks, James > diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c > index 2a5b338b2542..b2d4b7428ebc 100644 > --- a/arch/arm64/kernel/probes/kprobes.c > +++ b/arch/arm64/kernel/probes/kprobes.c > @@ -102,6 +102,10 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) > > if (in_exception_text(probe_addr)) > return -EINVAL; > + > + if (search_exception_tables(probe_addr)) > + return -EINVAL; > + > if (probe_addr >= (unsigned long) __start_rodata && > probe_addr <= (unsigned long) __end_rodata) > return -EINVAL; > @@ -477,8 +481,7 @@ bool arch_within_kprobe_blacklist(unsigned long addr) > (addr >= (unsigned long)__entry_text_start && > addr < (unsigned long)__entry_text_end) || > (addr >= (unsigned long)__idmap_text_start && > - addr < (unsigned long)__idmap_text_end) || > - !!search_exception_tables(addr)) > + addr < (unsigned long)__idmap_text_end)) > return true; > > if (!is_kernel_in_hyp_mode()) { >