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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88A57C433EF for ; Tue, 14 Jun 2022 14:32:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241074AbiFNOcS convert rfc822-to-8bit (ORCPT ); Tue, 14 Jun 2022 10:32:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345441AbiFNOcN (ORCPT ); Tue, 14 Jun 2022 10:32:13 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 130673A71D; Tue, 14 Jun 2022 07:32:12 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 6682CCE1ABA; Tue, 14 Jun 2022 14:32:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1E30BC3411B; Tue, 14 Jun 2022 14:32:07 +0000 (UTC) Date: Tue, 14 Jun 2022 10:32:05 -0400 From: Steven Rostedt To: Sai Prakash Ranjan Cc: , , , , , , , , , , , , Prasad Sodagudi Subject: Re: [PATCHv15 5/9] lib: Add register read/write tracing support Message-ID: <20220614103205.2d134546@gandalf.local.home> In-Reply-To: References: X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Wed, 18 May 2022 22:14:14 +0530 Sai Prakash Ranjan wrote: > From: Prasad Sodagudi > > Generic MMIO read/write i.e., __raw_{read,write}{b,l,w,q} accessors > are typically used to read/write from/to memory mapped registers > and can cause hangs or some undefined behaviour in following few > cases, > > * If the access to the register space is unclocked, for example: if > there is an access to multimedia(MM) block registers without MM > clocks. > > * If the register space is protected and not set to be accessible from > non-secure world, for example: only EL3 (EL: Exception level) access > is allowed and any EL2/EL1 access is forbidden. > > * If xPU(memory/register protection units) is controlling access to > certain memory/register space for specific clients. > > and more... > > Such cases usually results in instant reboot/SErrors/NOC or interconnect > hangs and tracing these register accesses can be very helpful to debug > such issues during initial development stages and also in later stages. > > So use ftrace trace events to log such MMIO register accesses which > provides rich feature set such as early enablement of trace events, > filtering capability, dumping ftrace logs on console and many more. > > Sample output: > > rwmmio_write: __qcom_geni_serial_console_write+0x160/0x1e0 width=32 val=0xa0d5d addr=0xfffffbfffdbff700 > rwmmio_post_write: __qcom_geni_serial_console_write+0x160/0x1e0 width=32 val=0xa0d5d addr=0xfffffbfffdbff700 > rwmmio_read: qcom_geni_serial_poll_bit+0x94/0x138 width=32 addr=0xfffffbfffdbff610 > rwmmio_post_read: qcom_geni_serial_poll_bit+0x94/0x138 width=32 val=0x0 addr=0xfffffbfffdbff610 > > Signed-off-by: Prasad Sodagudi > Co-developed-by: Sai Prakash Ranjan > Signed-off-by: Sai Prakash Ranjan > --- >From a tracing point of view, I do not see anything wrong with this patch. Acked-by: Steven Rostedt (Google) -- Steve