From patchwork Thu Jun 28 18:21:48 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Fernandes X-Patchwork-Id: 10494669 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 828936022E for ; Thu, 28 Jun 2018 18:22:54 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8515D2A13F for ; Thu, 28 Jun 2018 18:22:54 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 787D32A162; Thu, 28 Jun 2018 18:22:54 +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_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 EF88A2A13F for ; Thu, 28 Jun 2018 18:22:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967803AbeF1SWm (ORCPT ); Thu, 28 Jun 2018 14:22:42 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:40932 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030450AbeF1SWD (ORCPT ); Thu, 28 Jun 2018 14:22:03 -0400 Received: by mail-pf0-f194.google.com with SMTP id z24-v6so2978788pfe.7 for ; Thu, 28 Jun 2018 11:22:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=CV7DtXnAt/lUvrvcf20HpsDANAEU7RcF1ExBUfQsZos=; b=un0dNIDDQBTGqhcGZ1lVPrV7UYIXqfE0FEVnnM+NseEarBpSo/jcXd0y1qTT5oauBp JKb+cyfA9hEGEFyaOG4+Q5sYKWfaY8255Qlzk8O9K9BxJTVKeKlRzIFH6A9E3yW8x/IZ IL7+ap5Ew2xrYHJZV8WvbuTt/XoG3u4vMgTN0= 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=CV7DtXnAt/lUvrvcf20HpsDANAEU7RcF1ExBUfQsZos=; b=sgG60YjgiXxc2N3SVFyUQ7v6UwPVncdAac8dp3jhXhDYqHDo1WdEQlyvP03exQTKFx pS1PdSUmvoktbn/PumCsXBlDZIUwBRj+9I1YlxbUwG62arm4+n62Ec05iAfM08dLcZaR MIrlkja+P3L4WtDMY2YzQ1SbDk5WmlF/iJ6VOIQM0rCv7oXxxZcyOvuHXr2cwebnJASH jmeuUfLMeelcB/7q0BDheBd7gCQGGlAukbq2zd8BxqtXjlDkiMLaKhNRC01cgYpCFgkT 7fHV1aeXVEE1D7eI9DUdh1dauBGyY1iqT3fvfUfF9Vwr94PWJ66UYVbW0ZAvfdyjNzlo CU+g== X-Gm-Message-State: APt69E2Y+7sc48EASi2QUXdkqo0YPfFmf66C36PlLN4IyuddvD0J01Wu 2BfrCQBympw2cqGY2hheqKidwg== X-Google-Smtp-Source: ADUXVKJsHvuNAhWrzrMOVF6zs96xj5P84vZMLiUJKfHlSF2ad2zYKS5beFm501ihOHkGc8gpS9+YFw== X-Received: by 2002:a65:4dc3:: with SMTP id q3-v6mr9659697pgt.331.1530210123334; Thu, 28 Jun 2018 11:22:03 -0700 (PDT) Received: from joelaf.mtv.corp.google.com ([2620:0:1000:1600:3122:ea9c:d178:eb]) by smtp.gmail.com with ESMTPSA id q10-v6sm13686027pfj.7.2018.06.28.11.22.01 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 28 Jun 2018 11:22:02 -0700 (PDT) From: Joel Fernandes To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" , Andy Shevchenko , Boqun Feng , Byungchul Park , Ingo Molnar , Julia Cartwright , linux-kselftest@vger.kernel.org, Masami Hiramatsu , Mathieu Desnoyers , Namhyung Kim , Paul McKenney , Peter Zijlstra , Steven Rostedt , Thomas Glexiner , Tom Zanussi Subject: [PATCH v9 6/7] lib: Add module to simulate atomic sections for testing preemptoff tracers Date: Thu, 28 Jun 2018 11:21:48 -0700 Message-Id: <20180628182149.226164-7-joel@joelfernandes.org> X-Mailer: git-send-email 2.18.0.rc2.346.g013aa6912e-goog In-Reply-To: <20180628182149.226164-1-joel@joelfernandes.org> References: <20180628182149.226164-1-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 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 90dc5520b784..7831e747bf72 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");