From patchwork Thu Jun 7 20:38:14 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 10453535 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 B6A4360467 for ; Thu, 7 Jun 2018 20:39:54 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A42F429917 for ; Thu, 7 Jun 2018 20:39:54 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 98AA829924; Thu, 7 Jun 2018 20:39:54 +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=unavailable 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 2024929917 for ; Thu, 7 Jun 2018 20:39:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932487AbeFGUjm (ORCPT ); Thu, 7 Jun 2018 16:39:42 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:33549 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932516AbeFGUi6 (ORCPT ); Thu, 7 Jun 2018 16:38:58 -0400 Received: by mail-pf0-f194.google.com with SMTP id b17-v6so5480226pfi.0 for ; Thu, 07 Jun 2018 13:38:58 -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=g2JFCOwof1DHyJq7+FScs63IMBf/qXOwGEQoBoQIgY4=; b=ZMS0hvmTAfPEVF1tnuNHsSdHR4gySfJP2HomEH4aqfZxW4WP6vw4zw4Q36/o54c1Q/ 2WF554oY90xzRuUBYanEJCqB/tAdTJNUAKs5Hnks7ELrn6ZmRtulB/qRS2C7rLUjYsVU UENF/5Ht0gNQjlM+bgkuv+cWm5slSpnFdGIwNggvVWxoJCyY3qwpSFF39RTxfZI61N77 /+Ynlu59g6hBm3qfI1dmi+KcOjTLjOiDBw81v68xlubxsXFisjBcEdRBBDFJXwYvjoMX 7G0FHB6Ld0mh/+kgWjX0NdKGE0Wnd+nU8qdZZ6fra/WEii26MrrHfc1FLRtvnkSc2It2 oG0A== 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=g2JFCOwof1DHyJq7+FScs63IMBf/qXOwGEQoBoQIgY4=; b=X5FPD3MKuVnhHNjZvr8u/IHreA13ckqf55VKVJFkvu6iHvfLT/sWezGmTCEgEJYCNt 5LG3iaJA6LEU6V0Dyx2S5xXaBavYwwQDSwGvXCyTgvtdef7zS+xpmz6Z6YMpMPh/byWn Jn96KVys6wZzJ0QAuX0Q/hbz2R3kvHdClFVr8GMfouKt+yftjEkL/XwtF1XUsB+vqYSR 8vX8JLrSB4x8XEYyNXOv/e7Jju3DsgpEWqsn7Bf8+odnqzSqGp/d8RxKRYrX3g8SJBWJ ly1bowqL9+xWS8uR8v8DoHUIrTQ5CDdbOM0ILSFwBwHctNis0HWezHWAy3Np2NkKpw77 WIrA== X-Gm-Message-State: APt69E3prrP9TmE5L48hAUgE6JjUZ1Jer7SG6Kug4a6AaC2rCpB+wS6K yQOMe7epjUVRXlzeP9GjxVTkzQ== X-Google-Smtp-Source: ADUXVKJRmKX6siE+txpqce5Q7Qbgpbqz8UmcBWJ5Z9YkNsQ8zVrw56oIwm+JF+KUSkyPiJmD3tRGSw== X-Received: by 2002:a62:aa18:: with SMTP id e24-v6mr3117694pff.72.1528403937528; Thu, 07 Jun 2018 13:38:57 -0700 (PDT) Received: from joelaf.mtv.corp.google.com ([2620:0:1000:1600:3122:ea9c:d178:eb]) by smtp.gmail.com with ESMTPSA id v27-v6sm10324174pfi.23.2018.06.07.13.38.56 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 07 Jun 2018 13:38:56 -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)" , 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 Subject: [PATCH v9 6/7] lib: Add module to simulate atomic sections for testing preemptoff tracers Date: Thu, 7 Jun 2018 13:38:14 -0700 Message-Id: <20180607203815.255845-7-joel@joelfernandes.org> X-Mailer: git-send-email 2.17.1.1185.g55be947832-goog In-Reply-To: <20180607203815.255845-1-joel@joelfernandes.org> References: <20180607203815.255845-1-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-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 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..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");