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 72598C433F5 for ; Thu, 3 Feb 2022 06:27:39 +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:In-Reply-To:MIME-Version:Date: Message-ID:From:References:Cc:To:Subject:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=x2fNqQq+5K57xf5heXbDNCpCWntJ7TifyOLs7lKjklg=; b=kXWxn8NHQ7DqnZcMw4ptwsR2m6 e7XlhjYSvBTIEARTPctbx2NpwC1imSuGdpUpZwg63S+kP+ZbnYe+OTmIc/BeXBEsyaMvB+7DE9awe p1UB8at1JY6T9fY5uklDlzNEBreCciyFIMWBP6J8R5ChAJMq31L83eSpvNUaLH06IUJg8kqsVIQHl Om1JtD3r4uz7dBc4rcmvKK+UfFaBF5jUMh7ohTNKv3avcG9ibRO//O/lmNZfARU97daJVFyHf55Xm 24hL41aLizFnMHiED47WEWME6YE3ggiVdO6am10GV2qpTbDUleqY/1s5Syt5TBBsNakirw8NoLdcK dIhD8aQA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nFVZL-0004H5-8i; Thu, 03 Feb 2022 06:26:11 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nFVZH-0004GP-UJ for linux-arm-kernel@lists.infradead.org; Thu, 03 Feb 2022 06:26:09 +0000 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 2252B113E; Wed, 2 Feb 2022 22:26:05 -0800 (PST) Received: from [10.163.44.35] (unknown [10.163.44.35]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D5D933F774; Wed, 2 Feb 2022 22:26:02 -0800 (PST) Subject: Re: [PATCH] coresight: trbe: Move check for kernelspace unmapped at EL0 to probe To: Sudeep Holla , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: Mathieu Poirier , Suzuki K Poulose , Mike Leach , Leo Yan , coresight@lists.linaro.org References: <20220201122212.3009461-1-sudeep.holla@arm.com> From: Anshuman Khandual Message-ID: <01a43ba2-a633-f215-a688-2bda293b5a47@arm.com> Date: Thu, 3 Feb 2022 11:55:58 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20220201122212.3009461-1-sudeep.holla@arm.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220202_222608_083805_F616EE4D X-CRM114-Status: GOOD ( 23.36 ) 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 2/1/22 5:52 PM, Sudeep Holla wrote: > Currently with the check present in the module initialisation, it shouts > on all the systems irrespective of presence of coresight trace buffer > extensions. IIUC a system with CONFIG_CORESIGHT_TRBE enabled but without a TRBE DT i.e "arm,trace-buffer-extension" complains about kernel space unmapping at EL0 (even though it does not even really have TRBE HW to initialize). > > Similar to Arm SPE perf driver, move the check for kernelspace unmapping > when running at EL0 to the device probe instead of module initialisation. Makes sense. > > Cc: Mathieu Poirier > Cc: Suzuki K Poulose > Cc: Mike Leach > Cc: Leo Yan > Cc: Anshuman Khandual > Cc: coresight@lists.linaro.org > Signed-off-by: Sudeep Holla > --- > drivers/hwtracing/coresight/coresight-trbe.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c > index 276862c07e32..3fe2ce1ba5bf 100644 > --- a/drivers/hwtracing/coresight/coresight-trbe.c > +++ b/drivers/hwtracing/coresight/coresight-trbe.c > @@ -1423,6 +1423,11 @@ static int arm_trbe_device_probe(struct platform_device *pdev) > struct device *dev = &pdev->dev; > int ret; > Could you please add a similar comment like SPE driver regarding how the TRBE buffer will be inaccessible, if kernel gets unmapped at EL0 and trace capture will terminate. > + if (arm64_kernel_unmapped_at_el0()) { > + pr_err("TRBE wouldn't work if kernel gets unmapped at EL0\n"); > + return -EOPNOTSUPP; > + } > + > drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL); > if (!drvdata) > return -ENOMEM; > @@ -1484,11 +1489,6 @@ static int __init arm_trbe_init(void) > { > int ret; > > - if (arm64_kernel_unmapped_at_el0()) { > - pr_err("TRBE wouldn't work if kernel gets unmapped at EL0\n"); > - return -EOPNOTSUPP; > - } > - > ret = platform_driver_register(&arm_trbe_driver); > if (!ret) > return 0; > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel