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=-23.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 185B8C07E95 for ; Wed, 7 Jul 2021 13:35:24 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id D1D6261C73 for ; Wed, 7 Jul 2021 13:35:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D1D6261C73 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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:MIME-Version:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ZrjEWvNkmM3NwmhK1mkhs6N37ltFXwobRMQ62AR5qL8=; b=i+O/xcdK9Z51Vc gpXCw/IgHVQHYg07mBO8oa1t89k0AZI0qsX45OjLFrDomn66Iu7XTOLYBckMU6Da3/rI6HNKZpLOP GB+33ajmzTM7iCkPJmGyONoysn/2eTGzAdCUAY1n2+qxFPIIuw17PTupXbS1bAWyjr1tT8JfVtD3L WJ8nvlQJhlZ+T2YQWgvSrxmIBJ7IsHpi2JgNj/RQIUMJfX1YB5GKX1rPODv3JfIs/gee7ams9riTr wl2Qu1nrKeVqLTSafm1XwbIw2A+kJNJcw7d7WFdoP0Gbr9z6moyJbQUsCAJYShc8xqnLD6mQaOeds /8q9fdMx+2Tpyd5exa/w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m17gA-00Eu5d-Pc; Wed, 07 Jul 2021 13:33:31 +0000 Received: from mail-wm1-x329.google.com ([2a00:1450:4864:20::329]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1m17cz-00EspO-HG for linux-arm-kernel@lists.infradead.org; Wed, 07 Jul 2021 13:30:16 +0000 Received: by mail-wm1-x329.google.com with SMTP id g10so1868978wmh.2 for ; Wed, 07 Jul 2021 06:30:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=kWBYmHFzVaAtr0q3DL3loxqYVHyccUJehxRYe/jfvbg=; b=oIKKDnZnGrqv1Dc39WaPWkR6MyNNgr0LXOkTQxzcdKCjmX4S1wR2FJl0GqAYVL5ll2 dR6abtyttOwoG+Qk5EOawGEhBuQvDBO8gVMZo9QPmjE/PKeGnZ4EX+vPRmkSIgiOHp+t G9B9Qjwkn1VyL5JZH7c6hbW3AT3WdWdKip0GF/+Uy5NrH5mnVH/Uy0iqBEDAftGoxVIT K5zPCzDVS0tcI79/AdCqcmPep1QmhYajzJ44GzMhXcRQ6N62UolWAgLDHnE8jirJn8jX 1ci7Lv7IHdyyaftXDV77ioZTyyvTo5aGmb1TRH3x2xXP+rQJOLFPKjQW9se9VUIdEVgG DvOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=kWBYmHFzVaAtr0q3DL3loxqYVHyccUJehxRYe/jfvbg=; b=huAdRMP/q2B01kleYsTjOymPyYPokljcRT0d9BBztCbHF6a4dkANBW0zTTY5HeaCiM qoNVn/6iRL02u/yHPoB5d8aXLIXI1/EYTVVyKewvRhToqBIsEH6LpjDR+2TdXqE/WgmZ 9n8v8qHwQRC2vasYgUWGfzFKwjNAB+myKPNesn8sVr5isUpxlEycoKZ7S+Mds9RX6kjV li//JaQXhyNXAr9zECJJqH4OIzXfMhxHHeQ0q7986SOX2gVEzvfxQ17YbmS6MCIOW4nV F6kapsJaUAiHL/HEuU0+sHNqLejIsGi2am+ak8tGOtV4sIHLdEU7BFlJ+HBlUpNthKzV Kk8Q== X-Gm-Message-State: AOAM5318t+5jmsGUyG2TA+XCtIkEUU5wlVnJaBqOJRjUm3NjrzwnkYhb N1z9LUhTA8KGyFuu7Ux42Mc+F+wN3rh5Yw== X-Google-Smtp-Source: ABdhPJwl747RxWvPwgjGMCGBN7GkwTiv/Dbo6ozbGEnT7hT3LlAvHvBIk44ZdCxiuOrWwpDpnvjVxQ== X-Received: by 2002:a1c:9d16:: with SMTP id g22mr3181420wme.152.1625664611994; Wed, 07 Jul 2021 06:30:11 -0700 (PDT) Received: from linaro.org ([2a00:23c5:6809:2201:546d:7d59:1703:bf96]) by smtp.gmail.com with ESMTPSA id l16sm6632403wmj.47.2021.07.07.06.30.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Jul 2021 06:30:11 -0700 (PDT) From: Mike Leach To: linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org, mathieu.poirier@linaro.org, suzuki.poulose@arm.com Cc: leo.yan@linaro.org, alexander.shishkin@linux.intel.com, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, Mike Leach , Jonathan Corbet , linux-doc@vger.kernel.org Subject: [PATCH v8 10/10] Documentation: coresight: Add documentation for CoreSight config Date: Wed, 7 Jul 2021 14:30:03 +0100 Message-Id: <20210707133003.5414-11-mike.leach@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210707133003.5414-1-mike.leach@linaro.org> References: <20210707133003.5414-1-mike.leach@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210707_063013_660057_93F5E332 X-CRM114-Status: GOOD ( 36.50 ) 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: , MIME-Version: 1.0 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 Adds documentation for the CoreSight System configuration manager. Cc: Jonathan Corbet Cc: linux-doc@vger.kernel.org Signed-off-by: Mike Leach Reviewed-by: Mathieu Poirier --- .../trace/coresight/coresight-config.rst | 244 ++++++++++++++++++ Documentation/trace/coresight/coresight.rst | 16 ++ 2 files changed, 260 insertions(+) create mode 100644 Documentation/trace/coresight/coresight-config.rst diff --git a/Documentation/trace/coresight/coresight-config.rst b/Documentation/trace/coresight/coresight-config.rst new file mode 100644 index 000000000000..a4e3ef295240 --- /dev/null +++ b/Documentation/trace/coresight/coresight-config.rst @@ -0,0 +1,244 @@ +.. SPDX-License-Identifier: GPL-2.0 + +====================================== +CoreSight System Configuration Manager +====================================== + + :Author: Mike Leach + :Date: October 2020 + +Introduction +============ + +The CoreSight System Configuration manager is an API that allows the +programming of the CoreSight system with pre-defined configurations that +can then be easily enabled from sysfs or perf. + +Many CoreSight components can be programmed in complex ways - especially ETMs. +In addition, components can interact across the CoreSight system, often via +the cross trigger components such as CTI and CTM. These system settings can +be defined and enabled as named configurations. + + +Basic Concepts +============== + +This section introduces the basic concepts of a CoreSight system configuration. + + +Features +-------- + +A feature is a named set of programming for a CoreSight device. The programming +is device dependent, and can be defined in terms of absolute register values, +resource usage and parameter values. + +The feature is defined using a descriptor. This descriptor is used to load onto +a matching device, either when the feature is loaded into the system, or when the +CoreSight device is registered with the configuration manager. + +The load process involves interpreting the descriptor into a set of register +accesses in the driver - the resource usage and parameter descriptions +translated into appropriate register accesses. This interpretation makes it easy +and efficient for the feature to be programmed onto the device when required. + +The feature will not be active on the device until the feature is enabled, and +the device itself is enabled. When the device is enabled then enabled features +will be programmed into the device hardware. + +A feature is enabled as part of a configuration being enabled on the system. + + +Parameter Value +~~~~~~~~~~~~~~~ + +A parameter value is a named value that may be set by the user prior to the +feature being enabled that can adjust the behaviour of the operation programmed +by the feature. + +For example, this could be a count value in a programmed operation that repeats +at a given rate. When the feature is enabled then the current value of the +parameter is used in programming the device. + +The feature descriptor defines a default value for a parameter, which is used +if the user does not supply a new value. + +Users can update parameter values using the configfs API for the CoreSight +system - which is described below. + +The current value of the parameter is loaded into the device when the feature +is enabled on that device. + + +Configurations +-------------- + +A configuration defines a set of features that are to be used in a trace +session where the configuration is selected. For any trace session only one +configuration may be selected. + +The features defined may be on any type of device that is registered +to support system configuration. A configuration may select features to be +enabled on a class of devices - i.e. any ETMv4, or specific devices, e.g. a +specific CTI on the system. + +As with the feature, a descriptor is used to define the configuration. +This will define the features that must be enabled as part of the configuration +as well as any preset values that can be used to override default parameter +values. + + +Preset Values +~~~~~~~~~~~~~ + +Preset values are easily selectable sets of parameter values for the features +that the configuration uses. The number of values in a single preset set, equals +the sum of parameter values in the features used by the configuration. + +e.g. a configuration consists of 3 features, one has 2 parameters, one has +a single parameter, and another has no parameters. A single preset set will +therefore have 3 values. + +Presets are optionally defined by the configuration, up to 15 can be defined. +If no preset is selected, then the parameter values defined in the feature +are used as normal. + + +Operation +~~~~~~~~~ + +The following steps take place in the operation of a configuration. + +1) In this example, the configuration is 'autofdo', which has an + associated feature 'strobing' that works on ETMv4 CoreSight Devices. + +2) The configuration is enabled. For example 'perf' may select the + configuration as part of its command line:: + + perf record -e cs_etm/autofdo/ myapp + + which will enable the 'autofdo' configuration. + +3) perf starts tracing on the system. As each ETMv4 that perf uses for + trace is enabled, the configuration manager will check if the ETMv4 + has a feature that relates to the currently active configuration. + In this case 'strobing' is enabled & programmed into the ETMv4. + +4) When the ETMv4 is disabled, any registers marked as needing to be + saved will be read back. + +5) At the end of the perf session, the configuration will be disabled. + + +Viewing Configurations and Features +=================================== + +The set of configurations and features that are currently loaded into the +system can be viewed using the configfs API. + +Mount configfs as normal and the 'cs-syscfg' subsystem will appear:: + + $ ls /config + cs-syscfg stp-policy + +This has two sub-directories:: + + $ cd cs-syscfg/ + $ ls + configurations features + +The system has the configuration 'autofdo' built in. It may be examined as +follows:: + + $ cd configurations/ + $ ls + autofdo + $ cd autofdo/ + $ ls + description preset1 preset3 preset5 preset7 preset9 + feature_refs preset2 preset4 preset6 preset8 + $ cat description + Setup ETMs with strobing for autofdo + $ cat feature_refs + strobing + +Each preset declared has a preset subdirectory declared. The values for +the preset can be examined:: + + $ cat preset1/values + strobing.window = 0x1388 strobing.period = 0x2 + $ cat preset2/values + strobing.window = 0x1388 strobing.period = 0x4 + +The features referenced by the configuration can be examined in the features +directory:: + + $ cd ../../features/strobing/ + $ ls + description matches nr_params params + $ cat description + Generate periodic trace capture windows. + parameter 'window': a number of CPU cycles (W) + parameter 'period': trace enabled for W cycles every period x W cycles + $ cat matches + SRC_ETMV4 + $ cat nr_params + 2 + +Move to the params directory to examine and adjust parameters:: + + cd params + $ ls + period window + $ cd period + $ ls + value + $ cat value + 0x2710 + # echo 15000 > value + # cat value + 0x3a98 + +Parameters adjusted in this way are reflected in all device instances that have +loaded the feature. + + +Using Configurations in perf +============================ + +The configurations loaded into the CoreSight configuration management are +also declared in the perf 'cs_etm' event infrastructure so that they can +be selected when running trace under perf:: + + $ ls /sys/devices/cs_etm + configurations format perf_event_mux_interval_ms sinks type + events nr_addr_filters power + +Key directories here are 'configurations' - which lists the loaded +configurations, and 'events' - a generic perf directory which allows +selection on the perf command line.:: + + $ ls configurations/ + autofdo + $ cat configurations/autofdo + 0xa7c3dddd + +As with the sinks entries, this provides a hash of the configuration name. +The entry in the 'events' directory uses perfs built in syntax generator +to substitute the syntax for the name when evaluating the command:: + + $ ls events/ + autofdo + $ cat events/autofdo + configid=0xa7c3dddd + +The 'autofdo' configuration may be selected on the perf command line:: + + $ perf record -e cs_etm/autofdo/u --per-thread + +A preset to override the current parameter values can also be selected:: + + $ perf record -e cs_etm/autofdo,preset=1/u --per-thread + +When configurations are selected in this way, then the trace sink used is +automatically selected. diff --git a/Documentation/trace/coresight/coresight.rst b/Documentation/trace/coresight/coresight.rst index 169749efd8d1..7ec656c9f0dc 100644 --- a/Documentation/trace/coresight/coresight.rst +++ b/Documentation/trace/coresight/coresight.rst @@ -619,6 +619,20 @@ A separate documentation file is provided to explain the use of these devices. (:doc:`coresight-ect`) [#fourth]_. +CoreSight System Configuration +------------------------------ + +CoreSight components can be complex devices with many programming options. +Furthermore, components can be programmed to interact with each other across the +complete system. + +A CoreSight System Configuration manager is provided to allow these complex programming +configurations to be selected and used easily from perf and sysfs. + +See the separate document for further information. +(:doc:`coresight-config`) [#fifth]_. + + .. [#first] Documentation/ABI/testing/sysfs-bus-coresight-devices-stm .. [#second] Documentation/trace/stm.rst @@ -626,3 +640,5 @@ A separate documentation file is provided to explain the use of these devices. .. [#third] https://github.com/Linaro/perf-opencsd .. [#fourth] Documentation/trace/coresight/coresight-ect.rst + +.. [#fifth] Documentation/trace/coresight/coresight-config.rst -- 2.17.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel