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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, 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 52A75C432C0 for ; Wed, 20 Nov 2019 19:09:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 16562206DA for ; Wed, 20 Nov 2019 19:09:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="dp9gURhU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727696AbfKTTJ1 (ORCPT ); Wed, 20 Nov 2019 14:09:27 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:38060 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726685AbfKTTJW (ORCPT ); Wed, 20 Nov 2019 14:09:22 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xAKJ8sLl015112; Wed, 20 Nov 2019 19:08:54 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=from : to : cc : subject : date : message-id : in-reply-to : references; s=corp-2019-08-05; bh=OTkMRHAtyKC5SZUnZGwA9Q6Ai3RevxRZGRghgoS4JYE=; b=dp9gURhUGOP0KlOQUOMxuuE5bDKNZnmwNt/0z13MgfX4de5nRleQvaju1DYeKeWotlhs Y/kEMC5dwsZQdCgatuIgoqtW6e7npxTfjleSbEN5nIOp/f6xUSxY7I8UrUHS9f5SUNJA N4PwRZHgLcyuxEVKIxKgwXS1l6GdcZAtZuHsU24hYPhVI7ANs2iGG9AnkBy0Xtn/wmDL F4pL+8X66faYkmtKa8EqoEZtN8iBFc0/rQnHWXgwjPYeujxwcEGE6lOUrz6srroUds2x QlzIqXJz8QyUpWjX8QOFqLs10ybRLRtVMdxAErZkHi1coXazukea3+gTi2Ihi1ixfItB DA== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2120.oracle.com with ESMTP id 2wa9rqqh94-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 Nov 2019 19:08:54 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id xAKJ4EEw031747; Wed, 20 Nov 2019 19:08:53 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3020.oracle.com with ESMTP id 2wd46wxacw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 20 Nov 2019 19:08:53 +0000 Received: from abhmp0002.oracle.com (abhmp0002.oracle.com [141.146.116.8]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id xAKJ8qVA014419; Wed, 20 Nov 2019 19:08:53 GMT Received: from ca-common-hq.us.oracle.com (/10.211.9.209) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 20 Nov 2019 11:08:52 -0800 From: Divya Indi To: Steven Rostedt , linux-kernel@vger.kernel.org Cc: Divya Indi , Joe Jin , Srinivas Eeda , Aruna Ramakrishna , Manjunath Patil Subject: [PATCH 2/2] tracing: Sample module to demonstrate kernel access to Ftrace instances. Date: Wed, 20 Nov 2019 11:08:39 -0800 Message-Id: <1574276919-11119-3-git-send-email-divya.indi@oracle.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1574276919-11119-2-git-send-email-divya.indi@oracle.com> References: <1574276919-11119-1-git-send-email-divya.indi@oracle.com> <1574276919-11119-2-git-send-email-divya.indi@oracle.com> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9447 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1911200158 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9447 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-1911200159 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a sample module to demonstrate the use of the newly introduced and exported APIs to access Ftrace instances from within the kernel. Newly introduced APIs used here - 1. Create/Lookup a trace array with the given name. struct trace_array *trace_array_get_by_name(const char *name) 2. Destroy/Remove a trace array. int trace_array_destroy(struct trace_array *tr) 4. Enable/Disable trace events: int trace_array_set_clr_event(struct trace_array *tr, const char *system, const char *event, bool enable); Exported APIs - 1. trace_printk equivalent for instances. int trace_array_printk(struct trace_array *tr, unsigned long ip, const char *fmt, ...); 2. Helper function. void trace_printk_init_buffers(void); 3. To decrement the reference counter. void trace_array_put(struct trace_array *tr) Sample output(contents of /sys/kernel/tracing/instances/sample-instance) NOTE: Tracing disabled after ~5 sec) _-----=> irqs-off / _----=> need-resched | / _---=> hardirq/softirq || / _--=> preempt-depth ||| / delay TASK-PID CPU# |||| TIMESTAMP FUNCTION | | | |||| | | sample-instance-1452 [002] .... 49.430948: simple_thread: trace_array_printk: count=0 sample-instance-1452 [002] .... 49.430951: sample_event: count value=0 at jiffies=4294716608 sample-instance-1452 [002] .... 50.454847: simple_thread: trace_array_printk: count=1 sample-instance-1452 [002] .... 50.454849: sample_event: count value=1 at jiffies=4294717632 sample-instance-1452 [002] .... 51.478748: simple_thread: trace_array_printk: count=2 sample-instance-1452 [002] .... 51.478750: sample_event: count value=2 at jiffies=4294718656 sample-instance-1452 [002] .... 52.502652: simple_thread: trace_array_printk: count=3 sample-instance-1452 [002] .... 52.502655: sample_event: count value=3 at jiffies=4294719680 sample-instance-1452 [002] .... 53.526533: simple_thread: trace_array_printk: count=4 sample-instance-1452 [002] .... 53.526535: sample_event: count value=4 at jiffies=4294720704 sample-instance-1452 [002] .... 54.550438: simple_thread: trace_array_printk: count=5 sample-instance-1452 [002] .... 55.574336: simple_thread: trace_array_printk: count=6 Signed-off-by: Divya Indi Reviewed-by: Aruna Ramakrishna --- samples/Kconfig | 7 ++ samples/Makefile | 1 + samples/ftrace_instance/Makefile | 6 ++ samples/ftrace_instance/sample-trace-array.c | 131 +++++++++++++++++++++++++++ samples/ftrace_instance/sample-trace-array.h | 84 +++++++++++++++++ 5 files changed, 229 insertions(+) create mode 100644 samples/ftrace_instance/Makefile create mode 100644 samples/ftrace_instance/sample-trace-array.c create mode 100644 samples/ftrace_instance/sample-trace-array.h diff --git a/samples/Kconfig b/samples/Kconfig index d63cc8a..1c7864b 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -20,6 +20,13 @@ config SAMPLE_TRACE_PRINTK This builds a module that calls trace_printk() and can be used to test various trace_printk() calls from a module. +config SAMPLE_TRACE_ARRAY + tristate "Build sample module for kernel access to Ftrace instancess" + depends on EVENT_TRACING && m + help + This builds a module that demonstrates the use of various APIs to + access Ftrace instances from within the kernel. + config SAMPLE_KOBJECT tristate "Build kobject examples" help diff --git a/samples/Makefile b/samples/Makefile index debf892..02c444e 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -17,6 +17,7 @@ obj-$(CONFIG_SAMPLE_RPMSG_CLIENT) += rpmsg/ subdir-$(CONFIG_SAMPLE_SECCOMP) += seccomp obj-$(CONFIG_SAMPLE_TRACE_EVENTS) += trace_events/ obj-$(CONFIG_SAMPLE_TRACE_PRINTK) += trace_printk/ +obj-$(CONFIG_SAMPLE_TRACE_ARRAY) += ftrace_instance/ obj-$(CONFIG_VIDEO_PCI_SKELETON) += v4l/ obj-y += vfio-mdev/ subdir-$(CONFIG_SAMPLE_VFS) += vfs diff --git a/samples/ftrace_instance/Makefile b/samples/ftrace_instance/Makefile new file mode 100644 index 0000000..3603b13 --- /dev/null +++ b/samples/ftrace_instance/Makefile @@ -0,0 +1,6 @@ +# Builds a module that calls various routines to access Ftrace instances. +# To use(as root): insmod sample-trace-array.ko + +CFLAGS_sample-trace-array.o := -I$(src) + +obj-$(CONFIG_SAMPLE_TRACE_ARRAY) += sample-trace-array.o diff --git a/samples/ftrace_instance/sample-trace-array.c b/samples/ftrace_instance/sample-trace-array.c new file mode 100644 index 0000000..d523450 --- /dev/null +++ b/samples/ftrace_instance/sample-trace-array.c @@ -0,0 +1,131 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include +#include +#include +#include +#include + +/* + * Any file that uses trace points, must include the header. + * But only one file, must include the header by defining + * CREATE_TRACE_POINTS first. This will make the C code that + * creates the handles for the trace points. + */ +#define CREATE_TRACE_POINTS +#include "sample-trace-array.h" + +struct trace_array *tr; +static void mytimer_handler(struct timer_list *unused); +static struct task_struct *simple_tsk; + +/* + * mytimer: Timer setup to disable tracing for event "sample_event". This + * timer is only for the purposes of the sample module to demonstrate access of + * Ftrace instances from within kernel. + */ +static DEFINE_TIMER(mytimer, mytimer_handler); + +static void mytimer_handler(struct timer_list *unused) +{ + /* + * Disable tracing for event "sample_event". + */ + trace_array_set_clr_event(tr, "sample-subsystem", "sample_event", + false); +} + +static void simple_thread_func(int count) +{ + set_current_state(TASK_INTERRUPTIBLE); + schedule_timeout(HZ); + + /* + * Printing count value using trace_array_printk() - trace_printk() + * equivalent for the instance buffers. + */ + trace_array_printk(tr, _THIS_IP_, "trace_array_printk: count=%d\n", + count); + /* + * Tracepoint for event "sample_event". This will print the + * current value of count and current jiffies. + */ + trace_sample_event(count, jiffies); +} + +static int simple_thread(void *arg) +{ + int count = 0; + unsigned long delay = msecs_to_jiffies(5000); + + /* + * Enable tracing for "sample_event". + */ + trace_array_set_clr_event(tr, "sample-subsystem", "sample_event", true); + + /* + * Adding timer - mytimer. This timer will disable tracing after + * delay seconds. + * + */ + add_timer(&mytimer); + mod_timer(&mytimer, jiffies+delay); + + while (!kthread_should_stop()) + simple_thread_func(count++); + + del_timer(&mytimer); + + /* + * trace_array_put() decrements the reference counter associated with + * the trace array - "tr". We are done using the trace array, hence + * decrement the reference counter so that it can be destroyed using + * trace_array_destroy(). + */ + trace_array_put(tr); + + return 0; +} + +static int __init sample_trace_array_init(void) +{ + /* + * Return a pointer to the trace array with name "sample-instance" if it + * exists, else create a new trace array. + * + * NOTE: This function increments the reference counter + * associated with the trace array - "tr". + */ + tr = trace_array_get_by_name("sample-instance"); + + if (!tr) + return -1; + /* + * If context specific per-cpu buffers havent already been allocated. + */ + trace_printk_init_buffers(); + + simple_tsk = kthread_run(simple_thread, NULL, "sample-instance"); + if (IS_ERR(simple_tsk)) + return -1; + return 0; +} + +static void __exit sample_trace_array_exit(void) +{ + kthread_stop(simple_tsk); + + /* + * We are unloading our module and no longer require the trace array. + * Remove/destroy "tr" using trace_array_destroy() + */ + trace_array_destroy(tr); +} + +module_init(sample_trace_array_init); +module_exit(sample_trace_array_exit); + +MODULE_AUTHOR("Divya Indi"); +MODULE_DESCRIPTION("Sample module for kernel access to Ftrace instances"); +MODULE_LICENSE("GPL"); diff --git a/samples/ftrace_instance/sample-trace-array.h b/samples/ftrace_instance/sample-trace-array.h new file mode 100644 index 0000000..6f89624 --- /dev/null +++ b/samples/ftrace_instance/sample-trace-array.h @@ -0,0 +1,84 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * If TRACE_SYSTEM is defined, that will be the directory created + * in the ftrace directory under /sys/kernel/tracing/events/ + * + * The define_trace.h below will also look for a file name of + * TRACE_SYSTEM.h where TRACE_SYSTEM is what is defined here. + * In this case, it would look for sample-trace.h + * + * If the header name will be different than the system name + * (as in this case), then you can override the header name that + * define_trace.h will look up by defining TRACE_INCLUDE_FILE + * + * This file is called sample-trace-array.h but we want the system + * to be called "sample-subsystem". Therefore we must define the name of this + * file: + * + * #define TRACE_INCLUDE_FILE sample-trace-array + * + * As we do in the bottom of this file. + * + * Notice that TRACE_SYSTEM should be defined outside of #if + * protection, just like TRACE_INCLUDE_FILE. + */ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM sample-subsystem + +/* + * TRACE_SYSTEM is expected to be a C valid variable (alpha-numeric + * and underscore), although it may start with numbers. If for some + * reason it is not, you need to add the following lines: + */ +#undef TRACE_SYSTEM_VAR +#define TRACE_SYSTEM_VAR sample_subsystem + +/* + * But the above is only needed if TRACE_SYSTEM is not alpha-numeric + * and underscored. By default, TRACE_SYSTEM_VAR will be equal to + * TRACE_SYSTEM. As TRACE_SYSTEM_VAR must be alpha-numeric, if + * TRACE_SYSTEM is not, then TRACE_SYSTEM_VAR must be defined with + * only alpha-numeric and underscores. + * + * The TRACE_SYSTEM_VAR is only used internally and not visible to + * user space. + */ + +/* + * Notice that this file is not protected like a normal header. + * We also must allow for rereading of this file. The + * + * || defined(TRACE_HEADER_MULTI_READ) + * + * serves this purpose. + */ +#if !defined(_SAMPLE_TRACE_ARRAY_H) || defined(TRACE_HEADER_MULTI_READ) +#define _SAMPLE_TRACE_ARRAY_H + +#include +TRACE_EVENT(sample_event, + + TP_PROTO(int count, unsigned long time), + + TP_ARGS(count, time), + + TP_STRUCT__entry( + __field(int, count) + __field(unsigned long, time) + ), + + TP_fast_assign( + __entry->count = count; + __entry->time = time; + ), + + TP_printk("count value=%d at jiffies=%lu", __entry->count, + __entry->time) + ); +#endif + +#undef TRACE_INCLUDE_PATH +#define TRACE_INCLUDE_PATH . +#define TRACE_INCLUDE_FILE sample-trace-array +#include -- 1.8.3.1