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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,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 E3CA9C31E4C for ; Fri, 14 Jun 2019 05:15:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C492821473 for ; Fri, 14 Jun 2019 05:15:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726071AbfFNFPj (ORCPT ); Fri, 14 Jun 2019 01:15:39 -0400 Received: from foss.arm.com ([217.140.110.172]:54888 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725801AbfFNFPi (ORCPT ); Fri, 14 Jun 2019 01:15:38 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 29721367; Thu, 13 Jun 2019 22:15:37 -0700 (PDT) Received: from [10.162.41.168] (p8cg001049571a15.blr.arm.com [10.162.41.168]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B446E3F246; Thu, 13 Jun 2019 22:15:25 -0700 (PDT) From: Anshuman Khandual Subject: Re: [PATCH] mm: Generalize and rename notify_page_fault() as kprobe_page_fault() To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-mips@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org, Michal Hocko , Matthew Wilcox , Mark Rutland , Christophe Leroy , Stephen Rothwell , Andrey Konovalov , Michael Ellerman , Paul Mackerras , Russell King , Catalin Marinas , Will Deacon , Tony Luck , Fenghua Yu , Martin Schwidefsky , Heiko Carstens , Yoshinori Sato , "David S. Miller" , Thomas Gleixner , Peter Zijlstra , Ingo Molnar , Andy Lutomirski , Dave Hansen , Vineet Gupta , James Hogan , Paul Burton , Ralf Baechle References: <1560420444-25737-1-git-send-email-anshuman.khandual@arm.com> <20190613130408.3091869d8e50d0524157523f@linux-foundation.org> Message-ID: Date: Fri, 14 Jun 2019 10:45:44 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190613130408.3091869d8e50d0524157523f@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/14/2019 01:34 AM, Andrew Morton wrote: > On Thu, 13 Jun 2019 15:37:24 +0530 Anshuman Khandual wrote: > >> Architectures which support kprobes have very similar boilerplate around >> calling kprobe_fault_handler(). Use a helper function in kprobes.h to unify >> them, based on the x86 code. >> >> This changes the behaviour for other architectures when preemption is >> enabled. Previously, they would have disabled preemption while calling the >> kprobe handler. However, preemption would be disabled if this fault was >> due to a kprobe, so we know the fault was not due to a kprobe handler and >> can simply return failure. >> >> This behaviour was introduced in the commit a980c0ef9f6d ("x86/kprobes: >> Refactor kprobes_fault() like kprobe_exceptions_notify()") >> >> ... >> >> --- a/arch/arm/mm/fault.c >> +++ b/arch/arm/mm/fault.c >> @@ -30,28 +30,6 @@ >> >> #ifdef CONFIG_MMU >> >> -#ifdef CONFIG_KPROBES >> -static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr) > > Some architectures make this `static inline'. Others make it > `nokprobes_inline', others make it `static inline __kprobes'. The > latter seems weird - why try to put an inline function into > .kprobes.text? > > So.. what's the best thing to do here? You chose `static > nokprobe_inline' - is that the best approach, if so why? Does > kprobe_page_fault() actually need to be inlined? Matthew had suggested that (nokprobe_-inline) based on current x86 implementation. But every architecture already had an inlined definition which I did not want to deviate from. > > Also, some architectures had notify_page_fault returning int, others > bool. You chose bool and that seems appropriate and all callers are OK > with that. I would believe so. No one has complained yet :)