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=-23.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 5610FC4338F for ; Wed, 18 Aug 2021 19:41:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 358AB610E5 for ; Wed, 18 Aug 2021 19:41:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233881AbhHRTmQ (ORCPT ); Wed, 18 Aug 2021 15:42:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233384AbhHRTlR (ORCPT ); Wed, 18 Aug 2021 15:41:17 -0400 Received: from mail-pg1-x530.google.com (mail-pg1-x530.google.com [IPv6:2607:f8b0:4864:20::530]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA629C061292 for ; Wed, 18 Aug 2021 12:40:41 -0700 (PDT) Received: by mail-pg1-x530.google.com with SMTP id o2so3377734pgr.9 for ; Wed, 18 Aug 2021 12:40:41 -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 :mime-version:content-transfer-encoding; bh=CeDh9+h66IlmGCzm9QH+Z6bCFV/MM4axnNKbbUhIEms=; b=XKYs6KGtOjfI1EROpKFmJt8m6Lz56pqMon+mNeuBPPaieKQoA5Yt5JUJ5vreeCdMCw yjIC+Ra7nngKfFU2LrshlglybRigShjreFeyxornzUlZGCAAeii7I/auNGjk9nl13Y7p nOPF8fcgicLSDG4A45p40yF/tTMVtLX8AWmYmnKT4dVfNpQEfYw/86aZAXcmqpR9DTg+ ML/e4uBhUVcHjZ16Q1lOzq1HU84u5BxE6lhmrC0EMvE604ob1CLUlaW3F/y9n0i7CJ2W Sg8x3vV7iXPlsD0ZLgbmNoMnSr2bYQ4PS67RB/JO/xQzjJ46TYoe/Le52T6nEZIzhmOH 3WEQ== 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:mime-version:content-transfer-encoding; bh=CeDh9+h66IlmGCzm9QH+Z6bCFV/MM4axnNKbbUhIEms=; b=k+WFoSyzH+zCdW7oKMWA+AZnT6wilf3MoZP6PektZ2XJUfe2VXRciDcbU22++rIyFC a8XtJf7fMmHzQD+OUDqCqxJPQUuTJhvA0Xk6NQPBCdT2SMQd4K5yiJhzz4wpuRQu3zBo 7+71fO2FTTnDIKQhFxz1YhjebZNqSa3ZwBSbZSUW7MUVOL9QktdmKFIpi7il0GDOUIJc LX3KnxomF8TGdrWEcYGpmrGSsLhOwgxI8wEAY0ukE0Uh5ctdSGmu/hBWGTlTa6O3UZ4M 2PyfshC9jWGbhk9guT5oI3VJgFAVehVVUhLTm1tfXjDK5idZsyLEKzxEjQBckjqMzYA9 vZfg== X-Gm-Message-State: AOAM531aF8Tqo6+joV2O9ekprueyRnECOjwUXwolllnWWWsL/6/y5/le 5Fzk1AJDrDXDvhO0jyj7xU1jSA== X-Google-Smtp-Source: ABdhPJwyS444/Vua7WBzVUTz80GBgoYbN/O3H040QO39Y81xOaEBSHfDA/VrYBb0rkou+PUfvhncWQ== X-Received: by 2002:a63:cf58:: with SMTP id b24mr10446687pgj.97.1629315641239; Wed, 18 Aug 2021 12:40:41 -0700 (PDT) Received: from p14s.cg.shawcable.net (S0106889e681aac74.cg.shawcable.net. [68.147.0.187]) by smtp.gmail.com with ESMTPSA id k12sm2960137pjg.6.2021.08.18.12.40.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Aug 2021 12:40:40 -0700 (PDT) From: Mathieu Poirier To: gregkh@linuxfoundation.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 10/11] Documentation: coresight: Add documentation for CoreSight config Date: Wed, 18 Aug 2021 13:40:21 -0600 Message-Id: <20210818194022.379573-11-mathieu.poirier@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210818194022.379573-1-mathieu.poirier@linaro.org> References: <20210818194022.379573-1-mathieu.poirier@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mike Leach Adds documentation for the CoreSight System configuration manager. Cc: Jonathan Corbet Cc: linux-doc@vger.kernel.org Signed-off-by: Mike Leach Link: https://lore.kernel.org/r/20210723165444.1048-11-mike.leach@linaro.org [Fixed coresight-config.rst documentation link] Signed-off-by: Mathieu Poirier --- .../trace/coresight/coresight-config.rst | 244 ++++++++++++++++++ Documentation/trace/coresight/coresight.rst | 15 ++ 2 files changed, 259 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 1ec8dc35b1d8..a15571d96cc8 100644 --- a/Documentation/trace/coresight/coresight.rst +++ b/Documentation/trace/coresight/coresight.rst @@ -620,6 +620,19 @@ channels on the CTM (Cross Trigger Matrix). A separate documentation file is provided to explain the use of these devices. (Documentation/trace/coresight/coresight-ect.rst) [#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. +(Documentation/trace/coresight/coresight-config.rst) [#fifth]_. + .. [#first] Documentation/ABI/testing/sysfs-bus-coresight-devices-stm @@ -628,3 +641,5 @@ 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 -- 2.25.1