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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 5C853C46471 for ; Tue, 7 Aug 2018 16:57:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 221E321884 for ; Tue, 7 Aug 2018 16:57:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 221E321884 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389601AbeHGTMX (ORCPT ); Tue, 7 Aug 2018 15:12:23 -0400 Received: from foss.arm.com ([217.140.101.70]:56876 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727605AbeHGTMX (ORCPT ); Tue, 7 Aug 2018 15:12:23 -0400 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 C7CA980D; Tue, 7 Aug 2018 09:57:10 -0700 (PDT) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 9874F3F5B3; Tue, 7 Aug 2018 09:57:10 -0700 (PDT) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id B84361AE2D8E; Tue, 7 Aug 2018 17:57:14 +0100 (BST) Date: Tue, 7 Aug 2018 17:57:14 +0100 From: Will Deacon To: Sai Prakash Ranjan Cc: Steven Rostedt , Ingo Molnar , Laura Abbott , Kees Cook , Anton Vorontsov , Colin Cross , Jason Baron , Tony Luck , Arnd Bergmann , Catalin Marinas , Joel Fernandes , Masami Hiramatsu , Joe Perches , Jim Cromie , Rajendra Nayak , Vivek Gautam , Sibi Sankar , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, Greg Kroah-Hartman , Ingo Molnar , Tom Zanussi Subject: Re: [RFC PATCH 3/3] dynamic_debug: Add support for dynamic register trace Message-ID: <20180807165713.GJ21809@arm.com> References: <37c723a7892b21eb67b8447160d8d602703f321f.1533211509.git.saiprakash.ranjan@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <37c723a7892b21eb67b8447160d8d602703f321f.1533211509.git.saiprakash.ranjan@codeaurora.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 03, 2018 at 07:58:44PM +0530, Sai Prakash Ranjan wrote: > Introduce dynamic debug filtering mechanism to register > tracing as dynamic_rtb() which will reduce a lot of > overhead otherwise of tracing all the register reads/writes > in all files. > > Now we can just specify the file name or any wildcard pattern > as any other dynamic debug facility in bootargs and dynamic rtb > will just trace them and the output can be seen in pstore. > > TODO: Now we use same 'p' flag but will add a separate flag for register trace > later. > > Example for tracing all register reads/writes in drivers/soc/qcom/* below: > > # dyndbg="file drivers/soc/qcom/* +p" in bootargs > # reboot -f > # mount -t pstore pstore /sys/fs/pstore > # cat /sys/fs/pstore/rtb-ramoops-0 > [LOGK_WRITEL ] ts:1373030419 data:ffff00000d5065a4 qcom_smsm_probe+0x51c/0x668 > [LOGK_WRITEL ] ts:1373360576 data:ffff00000d506608 qcom_smsm_probe+0x51c/0x668 > > Also we add uncached_logk api to readl/writel definitions for arm64 > as of now. This can be extended to arm as well later for tracing. > > Signed-off-by: Sai Prakash Ranjan > --- > arch/arm64/include/asm/io.h | 93 +++++++++++++++++++++++++++++++++++ Putting all of this in the arch code, which basically duplicates everything, feels very wrong to me. Perhaps take a look at the ongoing work for instrumenting the atomics and take some inspiration from there? Ideally, the architecture just needs to provide the low-level primivites (which it already does) and the core can generate instruments versions if required. Will