From patchwork Thu Jun 21 22:36:47 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 10480823 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 1C34B602CB for ; Thu, 21 Jun 2018 22:36:52 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 079DD28E2B for ; Thu, 21 Jun 2018 22:36:52 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EFBCB28F2F; Thu, 21 Jun 2018 22:36:51 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.8 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI, T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4BD5928E2B for ; Thu, 21 Jun 2018 22:36:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933713AbeFUWgv (ORCPT ); Thu, 21 Jun 2018 18:36:51 -0400 Received: from mail-pg0-f65.google.com ([74.125.83.65]:41712 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933662AbeFUWgt (ORCPT ); Thu, 21 Jun 2018 18:36:49 -0400 Received: by mail-pg0-f65.google.com with SMTP id l65-v6so2049370pgl.8 for ; Thu, 21 Jun 2018 15:36:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=oOwfsnfdGEy+0Zi8MBTxiZIiiqfuLjViesbmC0Apsaw=; b=vRK5zBi7y98CJqh7EbIDF6xL+FFZz8JzSd9QebpK9GrOF+5sd/g78bt5/e6mLdnPUd dNl7wLxAPa4IERH70gKKJmyxeyf2tPUbIEx1C8Sa1LiV1gtG3CW54C8zw+erONnxZ9Tc VXvXhdjZQMk0LL9OoeGPonMlQF4Js9y27Es4lkm60Pc/7H0xCzpWOBStPRVVyFsuX0Cm /f1mJpMyPMiJXUkcY4AY6kE3e0Kmmve2bKtJswFBF/CND555lZ9zue0mpUnmu9xuTEVO Rb0T+jnEq0wJDv+f8tFPQQkzCwyMeIKhs9k43+b1xIjJq4eVNwoPa5ZZ+MUPj6MY3KPw V7UA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=oOwfsnfdGEy+0Zi8MBTxiZIiiqfuLjViesbmC0Apsaw=; b=CiwP1HWEb2K/XgohfIWQYCbVoC0SWebLmWynqyPwEsLkH5ynd0f1Eakxw2ANPTOtYH HVGV1JY8z2ILfZAVlWik428dxkAUWPyUydCXBxvgmh4p6viCRBnCnuBwZr3kaDVFeq3+ VC4ubOVw9lbM2jms7xV5l2hbh225oPDOySnA8AXD/T5Is01ifdHAghU6Zjs4cuqQHxZU W/AritlKZUbAlnpkRxYdHcXUU+YBitRGhrWX8OTy540wjhA90gY0wL/jyrCoEZtZf0AD J6YvVSVM5BQ47ls4HdQv8qf9dUkzPi26RxYYx77r+6+bFOEdiSmwG55CAwxxTsGveW9R KyIw== X-Gm-Message-State: APt69E1dKMqcXMTHEQ0ssHPpc2Qne4WkdQFd9yfY8u71xPNzk9IGGBeg r1rN/ROdKunlWdd/2pzTFkxqNQ== X-Google-Smtp-Source: ADUXVKJdPMec4dtslopAYLtv+S96+DKyD2EPnXTEw4b+ccHPNTUFbGEzPKNOniiCTfzlLPcOIgMC8g== X-Received: by 2002:a62:fc8d:: with SMTP id e135-v6mr29303816pfh.208.1529620608788; Thu, 21 Jun 2018 15:36:48 -0700 (PDT) Received: from localhost ([2620:0:1000:1600:3122:ea9c:d178:eb]) by smtp.gmail.com with ESMTPSA id l11-v6sm8638758pff.50.2018.06.21.15.36.47 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 21 Jun 2018 15:36:48 -0700 (PDT) Date: Thu, 21 Jun 2018 15:36:47 -0700 From: Joel Fernandes To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, "Joel Fernandes (Google)" , Andy Shevchenko , Boqun Feng , Byungchul Park , Erick Reyes , Ingo Molnar , Julia Cartwright , linux-kselftest@vger.kernel.org, Masami Hiramatsu , Mathieu Desnoyers , Namhyung Kim , Paul McKenney , Peter Zijlstra , Shuah Khan , Steven Rostedt , Thomas Glexiner , Todd Kjos , Tom Zanussi , Will Deacon Subject: [PATCH v9 6/7] lib: Add module to simulate atomic sections for testing preemptoff tracers Message-ID: <20180621223647.GA212425@joelaf.mtv.corp.google.com> References: <20180621223236.211495-1-joel@joelfernandes.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20180621223236.211495-1-joel@joelfernandes.org> X-Mailer: git-send-email 2.18.0.rc2.346.g013aa6912e-goog User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: "Joel Fernandes (Google)" In this patch we introduce a test module for simulating a long atomic section in the kernel which the preemptoff or irqsoff tracers can detect. This module is to be used only for test purposes and is default disabled. Following is the expected output (only briefly shown) that can be parsed to verify that the tracers are working correctly. We will use this from the kselftests in future patches. For the preemptoff tracer: echo preemptoff > /d/tracing/current_tracer sleep 1 insmod ./test_atomic_sections.ko atomic_mode=preempt atomic_time=500000 sleep 1 bash-4.3# cat /d/tracing/trace preempt -1066 2...2 0us@: atomic_sect_run <-atomic_sect_run preempt -1066 2...2 500002us : atomic_sect_run <-atomic_sect_run preempt -1066 2...2 500004us : tracer_preempt_on <-atomic_sect_run preempt -1066 2...2 500012us : => kthread => ret_from_fork For the irqsoff tracer: echo irqsoff > /d/tracing/current_tracer sleep 1 insmod ./test_atomic_sections.ko atomic_mode=irq atomic_time=500000 sleep 1 bash-4.3# cat /d/tracing/trace irq dis -1069 1d..1 0us@: atomic_sect_run irq dis -1069 1d..1 500001us : atomic_sect_run irq dis -1069 1d..1 500002us : tracer_hardirqs_on <-atomic_sect_run irq dis -1069 1d..1 500005us : => ret_from_fork Co-developed-by: Erick Reyes Cc: Andy Shevchenko Reviewed-by: Andy Shevchenko Signed-off-by: Joel Fernandes (Google) --- lib/Kconfig.debug | 8 ++++ lib/Makefile | 1 + lib/test_atomic_sections.c | 77 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 86 insertions(+) create mode 100644 lib/test_atomic_sections.c diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 8838d1158d19..622c90e1e066 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1956,6 +1956,14 @@ config TEST_KMOD If unsure, say N. +config TEST_ATOMIC_SECTIONS + tristate "Simulate atomic sections for tracers to detect" + depends on m + help + Select this option to build a test module that can help test atomic + sections by simulating them with a duration supplied as a module + parameter. Preempt disable and irq disable modes can be requested. + config TEST_DEBUG_VIRTUAL tristate "Test CONFIG_DEBUG_VIRTUAL feature" depends on DEBUG_VIRTUAL diff --git a/lib/Makefile b/lib/Makefile index 8153fdab287f..0c155c2d5db9 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -44,6 +44,7 @@ obj-y += string_helpers.o obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o obj-y += hexdump.o obj-$(CONFIG_TEST_HEXDUMP) += test_hexdump.o +obj-$(CONFIG_TEST_ATOMIC_SECTIONS) += test_atomic_sections.o obj-y += kstrtox.o obj-$(CONFIG_FIND_BIT_BENCHMARK) += find_bit_benchmark.o obj-$(CONFIG_TEST_BPF) += test_bpf.o diff --git a/lib/test_atomic_sections.c b/lib/test_atomic_sections.c new file mode 100644 index 000000000000..1eef518f0974 --- /dev/null +++ b/lib/test_atomic_sections.c @@ -0,0 +1,77 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Atomic section emulation test module + * + * Emulates atomic sections by disabling IRQs or preemption + * and doing a busy wait for a specified amount of time. + * This can be used for testing of different atomic section + * tracers such as irqsoff tracers. + * + * (c) 2018. Google LLC + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static ulong atomic_time = 100; +static char atomic_mode[10] = "irq"; + +module_param_named(atomic_time, atomic_time, ulong, S_IRUGO); +module_param_string(atomic_mode, atomic_mode, 10, S_IRUGO); +MODULE_PARM_DESC(atomic_time, "Period in microseconds (100 uS default)"); +MODULE_PARM_DESC(atomic_mode, "Mode of the test such as preempt or irq (default irq)"); + +static void busy_wait(ulong time) +{ + ktime_t start, end; + start = ktime_get(); + do { + end = ktime_get(); + if (kthread_should_stop()) + break; + } while (ktime_to_ns(ktime_sub(end, start)) < (time * 1000)); +} + +int atomic_sect_run(void *data) +{ + unsigned long flags; + + if (!strcmp(atomic_mode, "irq")) { + local_irq_save(flags); + busy_wait(atomic_time); + local_irq_restore(flags); + } else if (!strcmp(atomic_mode, "preempt")) { + preempt_disable(); + busy_wait(atomic_time); + preempt_enable(); + } + + return 0; +} + +static int __init atomic_sect_init(void) +{ + char task_name[50]; + struct task_struct *test_task; + + snprintf(task_name, sizeof(task_name), "%s_test", atomic_mode); + + test_task = kthread_run(atomic_sect_run, NULL, task_name); + return PTR_ERR_OR_ZERO(test_task); +} + +static void __exit atomic_sect_exit(void) +{ + return; +} + +module_init(atomic_sect_init) +module_exit(atomic_sect_exit) +MODULE_LICENSE("GPL v2");