From patchwork Sun Jul 31 19:03:46 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 12933208 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3CC6BC28B2C for ; Sun, 31 Jul 2022 19:04:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237835AbiGaTEo (ORCPT ); Sun, 31 Jul 2022 15:04:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49306 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237775AbiGaTEj (ORCPT ); Sun, 31 Jul 2022 15:04:39 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6A9F71056E; Sun, 31 Jul 2022 12:04:37 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 25D7F60FF9; Sun, 31 Jul 2022 19:04:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E233DC4315C; Sun, 31 Jul 2022 19:04:35 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.96) (envelope-from ) id 1oIEEt-007GB8-08; Sun, 31 Jul 2022 15:04:35 -0400 Message-ID: <20220731190434.876161484@goodmis.org> User-Agent: quilt/0.66 Date: Sun, 31 Jul 2022 15:03:46 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Wim Van Sebroeck , Guenter Roeck , Jonathan Corbet , Ingo Molnar , Thomas Gleixner , Peter Zijlstra , Will Deacon , Catalin Marinas , Marco Elver , Dmitry Vyukov , "Paul E. McKenney" , Shuah Khan , Gabriele Paoloni , Juri Lelli , Clark Williams , Tao Zhou , Randy Dunlap , linux-doc@vger.kernel.org, linux-trace-devel@vger.kernel.org, Daniel Bristot de Oliveira Subject: [for-next][PATCH 17/21] rv/monitor: Add the wip monitor References: <20220731190329.641602282@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org From: Daniel Bristot de Oliveira The wakeup in preemptive (wip) monitor verifies if the wakeup events always take place with preemption disabled: | | v #==================# H preemptive H <+ #==================# | | | | preempt_disable | preempt_enable v | sched_waking +------------------+ | +--------------- | | | | | non_preemptive | | +--------------> | | -+ +------------------+ The wakeup event always takes place with preemption disabled because of the scheduler synchronization. However, because the preempt_count and its trace event are not atomic with regard to interrupts, some inconsistencies might happen. The documentation illustrates one of these cases. Link: https://lkml.kernel.org/r/c98ca678df81115fddc04921b3c79720c836b18f.1659052063.git.bristot@kernel.org Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Will Deacon Cc: Catalin Marinas Cc: Marco Elver Cc: Dmitry Vyukov Cc: "Paul E. McKenney" Cc: Shuah Khan Cc: Gabriele Paoloni Cc: Juri Lelli Cc: Clark Williams Cc: Tao Zhou Cc: Randy Dunlap Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-trace-devel@vger.kernel.org Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (Google) --- Documentation/trace/rv/index.rst | 1 + Documentation/trace/rv/monitor_wip.rst | 55 ++++++++++++++++++++++++++ include/trace/events/rv.h | 10 +++++ kernel/trace/rv/Kconfig | 13 ++++++ kernel/trace/rv/Makefile | 1 + kernel/trace/rv/monitors/wip/wip.c | 51 +++++++----------------- tools/verification/models/wip.dot | 16 ++++++++ 7 files changed, 111 insertions(+), 36 deletions(-) create mode 100644 Documentation/trace/rv/monitor_wip.rst create mode 100644 tools/verification/models/wip.dot diff --git a/Documentation/trace/rv/index.rst b/Documentation/trace/rv/index.rst index db2ae3f90b90..4cb71ed628b8 100644 --- a/Documentation/trace/rv/index.rst +++ b/Documentation/trace/rv/index.rst @@ -10,3 +10,4 @@ Runtime Verification deterministic_automata.rst da_monitor_synthesis.rst da_monitor_instrumentation.rst + monitor_wip.rst diff --git a/Documentation/trace/rv/monitor_wip.rst b/Documentation/trace/rv/monitor_wip.rst new file mode 100644 index 000000000000..a95763438c48 --- /dev/null +++ b/Documentation/trace/rv/monitor_wip.rst @@ -0,0 +1,55 @@ +Monitor wip +=========== + +- Name: wip - wakeup in preemptive +- Type: per-cpu deterministic automaton +- Author: Daniel Bristot de Oliveira + +Description +----------- + +The wakeup in preemptive (wip) monitor is a sample per-cpu monitor +that verifies if the wakeup events always take place with +preemption disabled:: + + | + | + v + #==================# + H preemptive H <+ + #==================# | + | | + | preempt_disable | preempt_enable + v | + sched_waking +------------------+ | + +--------------- | | | + | | non_preemptive | | + +--------------> | | -+ + +------------------+ + +The wakeup event always takes place with preemption disabled because +of the scheduler synchronization. However, because the preempt_count +and its trace event are not atomic with regard to interrupts, some +inconsistencies might happen. For example:: + + preempt_disable() { + __preempt_count_add(1) + -------> smp_apic_timer_interrupt() { + preempt_disable() + do not trace (preempt count >= 1) + + wake up a thread + + preempt_enable() + do not trace (preempt count >= 1) + } + <------ + trace_preempt_disable(); + } + +This problem was reported and discussed here: + https://lore.kernel.org/r/cover.1559051152.git.bristot@redhat.com/ + +Specification +------------- +Grapviz Dot file in tools/verification/models/wip.dot diff --git a/include/trace/events/rv.h b/include/trace/events/rv.h index 20a2e09c6416..e972f27d8df3 100644 --- a/include/trace/events/rv.h +++ b/include/trace/events/rv.h @@ -56,6 +56,16 @@ DECLARE_EVENT_CLASS(error_da_monitor, __entry->event, __entry->state) ); + +#ifdef CONFIG_RV_MON_WIP +DEFINE_EVENT(event_da_monitor, event_wip, + TP_PROTO(char *state, char *event, char *next_state, bool final_state), + TP_ARGS(state, event, next_state, final_state)); + +DEFINE_EVENT(error_da_monitor, error_wip, + TP_PROTO(char *state, char *event), + TP_ARGS(state, event)); +#endif /* CONFIG_RV_MON_WIP */ #endif /* CONFIG_DA_MON_EVENTS_IMPLICIT */ #ifdef CONFIG_DA_MON_EVENTS_ID diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig index 0d9552b406c6..e50f3346164a 100644 --- a/kernel/trace/rv/Kconfig +++ b/kernel/trace/rv/Kconfig @@ -25,6 +25,19 @@ menuconfig RV For further information, see: Documentation/trace/rv/runtime-verification.rst +config RV_MON_WIP + depends on RV + depends on PREEMPT_TRACER + select DA_MON_EVENTS_IMPLICIT + bool "wip monitor" + help + Enable wip (wakeup in preemptive) sample monitor that illustrates + the usage of per-cpu monitors, and one limitation of the + preempt_disable/enable events. + + For further information, see: + Documentation/trace/rv/monitor_wip.rst + config RV_REACTORS bool "Runtime verification reactors" default y diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile index 8944274d9b41..b41109d2750a 100644 --- a/kernel/trace/rv/Makefile +++ b/kernel/trace/rv/Makefile @@ -2,3 +2,4 @@ obj-$(CONFIG_RV) += rv.o obj-$(CONFIG_RV_REACTORS) += rv_reactors.o +obj-$(CONFIG_RV_MON_WIP) += monitors/wip/wip.o diff --git a/kernel/trace/rv/monitors/wip/wip.c b/kernel/trace/rv/monitors/wip/wip.c index 79a054ca0cde..83cace53b9fa 100644 --- a/kernel/trace/rv/monitors/wip/wip.c +++ b/kernel/trace/rv/monitors/wip/wip.c @@ -10,44 +10,26 @@ #define MODULE_NAME "wip" -/* - * XXX: include required tracepoint headers, e.g., - * #include - */ #include +#include +#include -/* - * This is the self-generated part of the monitor. Generally, there is no need - * to touch this section. - */ #include "wip.h" -/* - * Declare the deterministic automata monitor. - * - * The rv monitor reference is needed for the monitor declaration. - */ struct rv_monitor rv_wip; DECLARE_DA_MON_PER_CPU(wip, unsigned char); -/* - * This is the instrumentation part of the monitor. - * - * This is the section where manual work is required. Here the kernel events - * are translated into model's event. - * - */ -static void handle_preempt_disable(void *data, /* XXX: fill header */) +static void handle_preempt_disable(void *data, unsigned long ip, unsigned long parent_ip) { da_handle_event_wip(preempt_disable_wip); } -static void handle_preempt_enable(void *data, /* XXX: fill header */) +static void handle_preempt_enable(void *data, unsigned long ip, unsigned long parent_ip) { - da_handle_event_wip(preempt_enable_wip); + da_handle_start_event_wip(preempt_enable_wip); } -static void handle_sched_waking(void *data, /* XXX: fill header */) +static void handle_sched_waking(void *data, struct task_struct *task) { da_handle_event_wip(sched_waking_wip); } @@ -60,9 +42,9 @@ static int enable_wip(void) if (retval) return retval; - rv_attach_trace_probe("wip", /* XXX: tracepoint */, handle_preempt_disable); - rv_attach_trace_probe("wip", /* XXX: tracepoint */, handle_preempt_enable); - rv_attach_trace_probe("wip", /* XXX: tracepoint */, handle_sched_waking); + rv_attach_trace_probe("wip", preempt_enable, handle_preempt_enable); + rv_attach_trace_probe("wip", sched_waking, handle_sched_waking); + rv_attach_trace_probe("wip", preempt_disable, handle_preempt_disable); return 0; } @@ -71,19 +53,16 @@ static void disable_wip(void) { rv_wip.enabled = 0; - rv_detach_trace_probe("wip", /* XXX: tracepoint */, handle_preempt_disable); - rv_detach_trace_probe("wip", /* XXX: tracepoint */, handle_preempt_enable); - rv_detach_trace_probe("wip", /* XXX: tracepoint */, handle_sched_waking); + rv_detach_trace_probe("wip", preempt_disable, handle_preempt_disable); + rv_detach_trace_probe("wip", preempt_enable, handle_preempt_enable); + rv_detach_trace_probe("wip", sched_waking, handle_sched_waking); da_monitor_destroy_wip(); } -/* - * This is the monitor register section. - */ struct rv_monitor rv_wip = { .name = "wip", - .description = "auto-generated wip", + .description = "wakeup in preemptive per-cpu testing monitor.", .enable = enable_wip, .disable = disable_wip, .reset = da_monitor_reset_all_wip, @@ -105,5 +84,5 @@ module_init(register_wip); module_exit(unregister_wip); MODULE_LICENSE("GPL"); -MODULE_AUTHOR("dot2k: auto-generated"); -MODULE_DESCRIPTION("wip"); +MODULE_AUTHOR("Daniel Bristot de Oliveira "); +MODULE_DESCRIPTION("wip: wakeup in preemptive - per-cpu sample monitor."); diff --git a/tools/verification/models/wip.dot b/tools/verification/models/wip.dot new file mode 100644 index 000000000000..2a53a9700a89 --- /dev/null +++ b/tools/verification/models/wip.dot @@ -0,0 +1,16 @@ +digraph state_automaton { + {node [shape = circle] "non_preemptive"}; + {node [shape = plaintext, style=invis, label=""] "__init_preemptive"}; + {node [shape = doublecircle] "preemptive"}; + {node [shape = circle] "preemptive"}; + "__init_preemptive" -> "preemptive"; + "non_preemptive" [label = "non_preemptive"]; + "non_preemptive" -> "non_preemptive" [ label = "sched_waking" ]; + "non_preemptive" -> "preemptive" [ label = "preempt_enable" ]; + "preemptive" [label = "preemptive"]; + "preemptive" -> "non_preemptive" [ label = "preempt_disable" ]; + { rank = min ; + "__init_preemptive"; + "preemptive"; + } +}