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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E2557C433EF for ; Tue, 14 Jun 2022 14:33:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=elUTL2H6+CT2RQgnOkOuS3OIBiwSrnklOqXaTdruWRQ=; b=4xICIFPdSNX1rN xymS7UBfy09FY6N0sfJ0CQQgh4iDimiHNolmUuflSaYcvRYxx+DekyNjt4L8Li+1PBSPI85YcG6w6 iCpdkBY6xI04n2ylqDCGtAODBEh3k5wFOOK2GcTvc089sG1hFPssHhQPo3sf5C4CtT9SWSOZnSPIn iTTlT3rNFMWGKsN+OCHbtUJYVqcRer423sBZlOEZZ7dQ3W45Nk/yTf6ZIxJFDMXzBLFu9pvCYfko8 o9b3NYzoiboRAKze5/8kkDd79e5WTPxMI4YR+bwfd1T1B8nRp/WjxUTJSIkWoE2raHs2ciAn03NdJ ftDtfIykqCAFK9Pzxfvg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o17aX-009xk6-1y; Tue, 14 Jun 2022 14:32:13 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o17aU-009xjA-7k for linux-arm-kernel@lists.infradead.org; Tue, 14 Jun 2022 14:32:11 +0000 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 dfw.source.kernel.org (Postfix) with ESMTPS id 1FC8D617A4; Tue, 14 Jun 2022 14:32:09 +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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220614_073210_356948_1553693B X-CRM114-Status: GOOD ( 16.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel