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, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 CFA39C282C2 for ; Wed, 13 Feb 2019 10:30:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 468B52190A for ; Wed, 13 Feb 2019 10:30:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389611AbfBMKaR (ORCPT ); Wed, 13 Feb 2019 05:30:17 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:50998 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732488AbfBMKaR (ORCPT ); Wed, 13 Feb 2019 05:30:17 -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 B2725A78; Wed, 13 Feb 2019 02:30:16 -0800 (PST) Received: from [10.1.197.45] (e112298-lin.cambridge.arm.com [10.1.197.45]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 795B53F575; Wed, 13 Feb 2019 02:30:14 -0800 (PST) Subject: Re: [PATCH v8 4/5] arm64: implement ftrace with regs To: Torsten Duwe , Mark Rutland , Will Deacon , Catalin Marinas , Steven Rostedt , Josh Poimboeuf , Ingo Molnar , Ard Biesheuvel , Arnd Bergmann , AKASHI Takahiro , Amit Daniel Kachhap Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, live-patching@vger.kernel.org References: <20190208150826.44EBC68DD2@newverein.lst.de> <20190208151019.9E7A968DDD@newverein.lst.de> From: Julien Thierry Message-ID: Date: Wed, 13 Feb 2019 10:30:12 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20190208151019.9E7A968DDD@newverein.lst.de> 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 Hi Torsten, On 08/02/2019 15:10, Torsten Duwe wrote: > Implement ftrace with regs, based on the new gcc flag > -fpatchable-function-entry (=2) > > Now that gcc8 added 2 NOPs at the beginning of each function, replace > the first NOP thus generated with a quick LR saver (move it to scratch > reg x9), so the 2nd replacement insn, the call to ftrace, does not > clobber the value. Ftrace will then generate the standard stack > frames. > > Note that patchable-function-entry in GCC disables IPA-RA, which means > ABI register calling conventions are obeyed and scratch registers such > as x9 are available. > > Introduce and handle an ftrace_regs_trampoline for module PLTs, right > after ftrace_trampoline in an ftrace_trampolines[2] array, and double > the size of the corresponding special section. > > Signed-off-by: Torsten Duwe > > --- > arch/arm64/include/asm/ftrace.h | 16 ++++ > arch/arm64/include/asm/module.h | 3 > arch/arm64/kernel/entry-ftrace.S | 125 +++++++++++++++++++++++++++++++++++++-- > arch/arm64/kernel/ftrace.c | 117 ++++++++++++++++++++++++++++-------- > arch/arm64/kernel/module-plts.c | 3 > arch/arm64/kernel/module.c | 2 > 6 files changed, 231 insertions(+), 35 deletions(-) [...] > --- a/arch/arm64/include/asm/module.h > +++ b/arch/arm64/include/asm/module.h > @@ -32,7 +32,8 @@ struct mod_arch_specific { > struct mod_plt_sec init; > > /* for CONFIG_DYNAMIC_FTRACE */ > - struct plt_entry *ftrace_trampoline; > + struct plt_entry *ftrace_trampolines; > +#define MOD_ARCH_NR_FTRACE_TRAMPOLINES 2 Nit: I'd define this outside of the struct, just below MODULE_ARCH_VERMAGIC, and use the prefix "MODULE_ARCH" instead of "MOD_ARCH" as this seem to be already in use for a few other defines. Otherwise things look good to me: Reviewed-by: Julien Thierry Cheers, -- Julien Thierry