From patchwork Thu May 24 01:21:56 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 10422589 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 35B886016C for ; Thu, 24 May 2018 01:23:03 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1E8B6292EF for ; Thu, 24 May 2018 01:23:03 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 12F03292F7; Thu, 24 May 2018 01:23:03 +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 7DF76292EF for ; Thu, 24 May 2018 01:23:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935459AbeEXBWn (ORCPT ); Wed, 23 May 2018 21:22:43 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:33220 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935435AbeEXBWi (ORCPT ); Wed, 23 May 2018 21:22:38 -0400 Received: by mail-pf0-f194.google.com with SMTP id a20-v6so11361599pfo.0 for ; Wed, 23 May 2018 18:22:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=t6Y+zibCUc9sagX2qEpc/7qKIOMI7qn3d2S0bGko0eo=; b=vH0WKSSNP9/SSC10Burc8Pfzd6EmdAkculvHyPDyEWeysRSZicbg93geUL5m3mLBXh g9nz6RDwItjk3PaANM1PC9rOUR26GL9Np8S5p9kj9P/h104GtY8V7uXiRuDrQsmlGuBv FcOjhyPdjhQwAWVfTFWDkgY9cu7VE/OASVcntp7VtxEW/h+vrwtd02tR2OW0hVkXghi4 QZAqxH3JWjxI6vukR3npRgQ9K5cXE63lbstnjb3tuQ8GfKSdzXTAluPqHcqoLjBW5sIJ qNME68hOvVXP3VQVzS4sWp+Cx2pVPXaq/pTN0BDn7ZebPyYV7+54eixEzp7AjA7yS/mQ oCPg== 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=t6Y+zibCUc9sagX2qEpc/7qKIOMI7qn3d2S0bGko0eo=; b=XXtbqZk7bQShtPH3YyGp0TaYKK1n6S/6Rn1aQrxRF0eop5o+LnOVKjoFi20jWxKJWZ KgE6IjMNsGHvEslLMeqscydTpotzi6yEHB+ej+IGrpCaN/SRk4CcK2UV8H4/Jf3fX4Wg 6ZRLHPB6/sLJm72eOXp2hALxu77IXTDfmLms1fWI9Wwjaa5APuGciOFpqsugqS4YXMsW 5Zt1/WfKskXwUktNkaxqUVkppaRtjYixJNzQaqNy3+wqHtAVPIjf25tea2l6IPcDfebs dyNeZJ4VX8BFKdzkqYCnOLdiq3kp8HeKnMPiHlXvv7hDuYNxMeL0Ud50oKbxXwzy1wvS 3bXQ== X-Gm-Message-State: ALKqPwdG4SQvgix7v+V7oHtQPNMp/Sf2Z1Sur3KlnUnf0mOOUjcZvI/G YlIFioY4mR2DySEjBAcbUjrYyg== X-Google-Smtp-Source: AB8JxZpXmNjtXCTIxsBgtnzthM1Ay4KIgDq7Z1zrdLemG5eprEAQven6jy9Z02m0yoJA/PFizjFsFA== X-Received: by 2002:a63:6285:: with SMTP id w127-v6mr4125654pgb.164.1527124956483; Wed, 23 May 2018 18:22:36 -0700 (PDT) Received: from joelaf.mtv.corp.google.com ([2620:0:1000:1600:3122:ea9c:d178:eb]) by smtp.gmail.com with ESMTPSA id g15-v6sm26070996pgv.58.2018.05.23.18.22.35 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 23 May 2018 18:22:35 -0700 (PDT) From: Joel Fernandes X-Google-Original-From: Joel Fernandes To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, "Joel Fernandes (Google)" , 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 Subject: [PATCH v7 7/8] lib: Add module to simulate atomic sections for testing preemptoff tracers Date: Wed, 23 May 2018 18:21:56 -0700 Message-Id: <20180524012157.181277-8-joel@joelfernandes.org> X-Mailer: git-send-email 2.17.0.441.gb46fe60e1d-goog In-Reply-To: <20180524012157.181277-1-joel@joelfernandes.org> References: <20180524012157.181277-1-joel@joelfernandes.org> 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-authored-by: Erick Reyes Signed-off-by: Joel Fernandes (Google) --- lib/Kconfig.debug | 8 ++++ lib/Makefile | 1 + lib/test_atomic_sections.c | 79 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 88 insertions(+) create mode 100644 lib/test_atomic_sections.c diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c40c7b734cd1..faebf0fe3bcf 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1933,6 +1933,14 @@ 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 ce20696d5a92..e82cf5445b7b 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -46,6 +46,7 @@ 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..2c8c6419d183 --- /dev/null +++ b/lib/test_atomic_sections.c @@ -0,0 +1,79 @@ +// 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 int atomic_time = 100; +static char atomic_mode[10] = "irq"; + +module_param_named(atomic_time, atomic_time, int, 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(int 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)); +} + +void 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(); + } + do_exit(0); +} + +static int __init atomic_sect_init(void) +{ + char task_name[50]; + struct task_struct *test_task; + + snprintf(task_name, 50, "%s dis test", atomic_mode); + + test_task = kthread_run((void*)atomic_sect_run, NULL, task_name); + if (IS_ERR(test_task)) + return PTR_ERR(test_task); + + return 0; +} + +static void __exit atomic_sect_exit(void) +{ + return; +} + +module_init(atomic_sect_init) +module_exit(atomic_sect_exit) +MODULE_LICENSE("GPL");