From patchwork Fri Jul 29 09:38:40 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932243 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 BC1B0C19F2B for ; Fri, 29 Jul 2022 09:39:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235617AbiG2JjU (ORCPT ); Fri, 29 Jul 2022 05:39:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37280 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235557AbiG2JjS (ORCPT ); Fri, 29 Jul 2022 05:39:18 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D47F485F9F; Fri, 29 Jul 2022 02:39:15 -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 sin.source.kernel.org (Postfix) with ESMTPS id 0CE10CE2876; Fri, 29 Jul 2022 09:39:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 797DAC4347C; Fri, 29 Jul 2022 09:39:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087552; bh=UDFnaF+MEHHMpTFYqf9QSstTaP+2TvjNKKA21kUPTrc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AkGayKDmLuyM3mDXCQtA26Sj4G3M8TCmyiW+ZBNc8MsU3Yp1enZgHiMyoEXu6c9df 2mvTed6DtHlYA404AygB/4rCyjA5UfZNEkyb91P12aEH1C9eu8F5uA3ESuFNDhqMxN H3vBKX24UYaB/dwkATqfWlx3H7RyGjzloktb0eBrRMGV085D1RxipMjkh6deqWOpth NtadeBbCP/0neFIQbgGY4H+mwJ42sSinGB+Rhh9X5X7VyMLjXey5qdPUyFh5v9Y8Rr 7VSGWWpWHVsOzIb61WGvmXmKmb8mpAyVGm3cRjvUyeG/gdUvNdLsazJiitGt2dRFeK td0cziCNcdhGg== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 01/16] rv: Add Runtime Verification (RV) interface Date: Fri, 29 Jul 2022 11:38:40 +0200 Message-Id: X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org RV is a lightweight (yet rigorous) method that complements classical exhaustive verification techniques (such as model checking and theorem proving) with a more practical approach to complex systems. RV works by analyzing the trace of the system's actual execution, comparing it against a formal specification of the system behavior. RV can give precise information on the runtime behavior of the monitored system while enabling the reaction for unexpected events, avoiding, for example, the propagation of a failure on safety-critical systems. The development of this interface roots in the development of the paper: De Oliveira, Daniel Bristot; Cucinotta, Tommaso; De Oliveira, Romulo Silva. Efficient formal verification for the Linux kernel. In: International Conference on Software Engineering and Formal Methods. Springer, Cham, 2019. p. 315-332. And: De Oliveira, Daniel Bristot. Automata-based formal analysis and verification of the real-time Linux kernel. PhD Thesis, 2020. The RV interface resembles the tracing/ interface on purpose. The current path for the RV interface is /sys/kernel/tracing/rv/. It presents these files: "available_monitors" - List the available monitors, one per line. For example: # cat available_monitors wip wwnr "enabled_monitors" - Lists the enabled monitors, one per line; - Writing to it enables a given monitor; - Writing a monitor name with a '!' prefix disables it; - Truncating the file disables all enabled monitors. For example: # cat enabled_monitors # echo wip > enabled_monitors # echo wwnr >> enabled_monitors # cat enabled_monitors wip wwnr # echo '!wip' >> enabled_monitors # cat enabled_monitors wwnr # echo > enabled_monitors # cat enabled_monitors # Note that more than one monitor can be enabled concurrently. "monitoring_on" - It is an on/off general switcher for monitoring. Note that it does not disable enabled monitors or detach events, but stop the per-entity monitors of monitoring the events received from the system. It resembles the "tracing_on" switcher. "monitors/" Each monitor will have its one directory inside "monitors/". There the monitor specific files will be presented. The "monitors/" directory resembles the "events" directory on tracefs. For example: # cd monitors/wip/ # ls desc enable # cat desc wakeup in preemptive per-cpu testing monitor. # cat enable 0 For further information, see the comments in the header of kernel/trace/rv/rv.c from this patch. Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- include/linux/rv.h | 43 +++ include/linux/sched.h | 11 + kernel/trace/Kconfig | 2 + kernel/trace/Makefile | 1 + kernel/trace/rv/Kconfig | 12 + kernel/trace/rv/Makefile | 3 + kernel/trace/rv/rv.c | 782 +++++++++++++++++++++++++++++++++++++++ kernel/trace/rv/rv.h | 33 ++ kernel/trace/trace.c | 2 + kernel/trace/trace.h | 9 + 10 files changed, 898 insertions(+) create mode 100644 include/linux/rv.h create mode 100644 kernel/trace/rv/Kconfig create mode 100644 kernel/trace/rv/Makefile create mode 100644 kernel/trace/rv/rv.c create mode 100644 kernel/trace/rv/rv.h diff --git a/include/linux/rv.h b/include/linux/rv.h new file mode 100644 index 000000000000..d8fa9e8be94a --- /dev/null +++ b/include/linux/rv.h @@ -0,0 +1,43 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Runtime Verification. + * + * For futher information, see: kernel/trace/rv/rv.c. + */ +#ifndef _LINUX_RV_H +#define _LINUX_RV_H + +#ifdef CONFIG_RV + +/* + * Per-task RV monitors count. Nowadays fixed in RV_PER_TASK_MONITORS. + * If we find justification for more monitors, we can think about + * adding more or developing a dynamic method. So far, none of + * these are justified. + */ +#define RV_PER_TASK_MONITORS 1 +#define RV_PER_TASK_MONITOR_INIT (RV_PER_TASK_MONITORS) + +/* + * Futher monitor types are expected, so make this a union. + */ +union rv_task_monitor { +}; + +struct rv_monitor { + const char *name; + const char *description; + bool enabled; + int (*enable)(void); + void (*disable)(void); + void (*reset)(void); +}; + +bool rv_monitoring_on(void); +int rv_unregister_monitor(struct rv_monitor *monitor); +int rv_register_monitor(struct rv_monitor *monitor); +int rv_get_task_monitor_slot(void); +void rv_put_task_monitor_slot(int slot); + +#endif /* CONFIG_RV */ +#endif /* _LINUX_RV_H */ diff --git a/include/linux/sched.h b/include/linux/sched.h index c46f3a63b758..b5da3e7c3a04 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -34,6 +34,7 @@ #include #include #include +#include #include /* task_struct member predeclarations (sorted alphabetically): */ @@ -1500,6 +1501,16 @@ struct task_struct { struct callback_head l1d_flush_kill; #endif +#ifdef CONFIG_RV + /* + * Per-task RV monitor. Nowadays fixed in RV_PER_TASK_MONITORS. + * If we find justification for more monitors, we can think + * about adding more or developing a dynamic method. So far, + * none of these are justified. + */ + union rv_task_monitor rv[RV_PER_TASK_MONITORS]; +#endif + /* * New fields for task_struct should be added above here, so that * they are included in the randomized portion of task_struct. diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index ccd6a5ade3e9..1052126bdca2 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -1106,4 +1106,6 @@ config HIST_TRIGGERS_DEBUG If unsure, say N. +source "kernel/trace/rv/Kconfig" + endif # FTRACE diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 0d261774d6f3..c6651e16b557 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -106,5 +106,6 @@ obj-$(CONFIG_FPROBE) += fprobe.o obj-$(CONFIG_RETHOOK) += rethook.o obj-$(CONFIG_TRACEPOINT_BENCHMARK) += trace_benchmark.o +obj-$(CONFIG_RV) += rv/ libftrace-y := ftrace.o diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig new file mode 100644 index 000000000000..6d127cdb00dd --- /dev/null +++ b/kernel/trace/rv/Kconfig @@ -0,0 +1,12 @@ +# SPDX-License-Identifier: GPL-2.0-only +# +menuconfig RV + bool "Runtime Verification" + depends on TRACING + help + Enable the kernel runtime verification infrastructure. RV is a + lightweight (yet rigorous) method that complements classical + exhaustive verification techniques (such as model checking and + theorem proving). RV works by analyzing the trace of the system's + actual execution, comparing it against a formal specification of + the system behavior. diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile new file mode 100644 index 000000000000..fd995379df67 --- /dev/null +++ b/kernel/trace/rv/Makefile @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0 + +obj-$(CONFIG_RV) += rv.o diff --git a/kernel/trace/rv/rv.c b/kernel/trace/rv/rv.c new file mode 100644 index 000000000000..731cc961cc70 --- /dev/null +++ b/kernel/trace/rv/rv.c @@ -0,0 +1,782 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira + * + * This is the online Runtime Verification (RV) interface. + * + * RV is a lightweight (yet rigorous) method that complements classical + * exhaustive verification techniques (such as model checking and + * theorem proving) with a more practical approach to complex systems. + * + * RV works by analyzing the trace of the system's actual execution, + * comparing it against a formal specification of the system behavior. + * RV can give precise information on the runtime behavior of the + * monitored system while enabling the reaction for unexpected + * events, avoiding, for example, the propagation of a failure on + * safety-critical systems. + * + * The development of this interface roots in the development of the + * paper: + * + * De Oliveira, Daniel Bristot; Cucinotta, Tommaso; De Oliveira, Romulo + * Silva. Efficient formal verification for the Linux kernel. In: + * International Conference on Software Engineering and Formal Methods. + * Springer, Cham, 2019. p. 315-332. + * + * And: + * + * De Oliveira, Daniel Bristot, et al. Automata-based formal analysis + * and verification of the real-time Linux kernel. PhD Thesis, 2020. + * + * == Runtime monitor interface == + * + * A monitor is the central part of the runtime verification of a system. + * + * The monitor stands in between the formal specification of the desired + * (or undesired) behavior, and the trace of the actual system. + * + * In Linux terms, the runtime verification monitors are encapsulated + * inside the "RV monitor" abstraction. A RV monitor includes a reference + * model of the system, a set of instances of the monitor (per-cpu monitor, + * per-task monitor, and so on), and the helper functions that glue the + * monitor to the system via trace. Generally, a monitor includes some form + * of trace output as a reaction for event parsing and exceptions, + * as depicted bellow: + * + * Linux +----- RV Monitor ----------------------------------+ Formal + * Realm | | Realm + * +-------------------+ +----------------+ +-----------------+ + * | Linux kernel | | Monitor | | Reference | + * | Tracing | -> | Instance(s) | <- | Model | + * | (instrumentation) | | (verification) | | (specification) | + * +-------------------+ +----------------+ +-----------------+ + * | | | + * | V | + * | +----------+ | + * | | Reaction | | + * | +--+--+--+-+ | + * | | | | | + * | | | +-> trace output ? | + * +------------------------|--|----------------------+ + * | +----> panic ? + * +-------> + * + * This file implements the interface for loading RV monitors, and + * to control the verification session. + * + * == Registering monitors == + * + * The struct rv_monitor defines a set of callback functions to control + * a verification session. For instance, when a given monitor is enabled, + * the "enable" callback function is called to hook the instrumentation + * functions to the kernel trace events. The "disable" function is called + * when disabling the verification session. + * + * A RV monitor is registered via: + * int rv_register_monitor(struct rv_monitor *monitor); + * And unregistered via: + * int rv_unregister_monitor(struct rv_monitor *monitor); + * + * == User interface == + * + * The user interface resembles kernel tracing interface. It presents + * these files: + * + * "available_monitors" + * - List the available monitors, one per line. + * + * For example: + * # cat available_monitors + * wip + * wwnr + * + * "enabled_monitors" + * - Lists the enabled monitors, one per line; + * - Writing to it enables a given monitor; + * - Writing a monitor name with a '!' prefix disables it; + * - Truncating the file disables all enabled monitors. + * + * For example: + * # cat enabled_monitors + * # echo wip > enabled_monitors + * # echo wwnr >> enabled_monitors + * # cat enabled_monitors + * wip + * wwnr + * # echo '!wip' >> enabled_monitors + * # cat enabled_monitors + * wwnr + * # echo > enabled_monitors + * # cat enabled_monitors + * # + * + * Note that more than one monitor can be enabled concurrently. + * + * "monitoring_on" + * - It is an on/off general switcher for monitoring. Note + * that it does not disable enabled monitors or detach events, + * but stops the per-entity monitors from monitoring the events + * received from the instrumentation. It resembles the "tracing_on" + * switcher. + * + * "monitors/" + * Each monitor will have its own directory inside "monitors/". There + * the monitor specific files will be presented. + * The "monitors/" directory resembles the "events" directory on + * tracefs. + * + * For example: + * # cd monitors/wip/ + * # ls + * desc enable + * # cat desc + * auto-generated wakeup in preemptive monitor. + * # cat enable + * 0 + */ + +#include +#include +#include +#include + +#include "rv.h" + +DEFINE_MUTEX(rv_interface_lock); + +static struct rv_interface rv_root; + +struct dentry *get_monitors_root(void) +{ + return rv_root.monitors_dir; +} + +/* + * Interface for the monitor register. + */ +static LIST_HEAD(rv_monitors_list); + +static int task_monitor_count; +static bool task_monitor_slots[RV_PER_TASK_MONITORS]; + +int rv_get_task_monitor_slot(void) +{ + int i; + + lockdep_assert_held(&rv_interface_lock); + + if (task_monitor_count == RV_PER_TASK_MONITORS) + return -EBUSY; + + task_monitor_count++; + + for (i = 0; i < RV_PER_TASK_MONITORS; i++) { + if (task_monitor_slots[i] == false) { + task_monitor_slots[i] = true; + return i; + } + } + + WARN_ONCE(1, "RV task_monitor_count and slots are out of sync\n"); + + return -EINVAL; +} + +void rv_put_task_monitor_slot(int slot) +{ + lockdep_assert_held(&rv_interface_lock); + + if (slot < 0 || slot >= RV_PER_TASK_MONITORS) { + WARN_ONCE(1, "RV releasing an invalid slot!: %d\n", slot); + return; + } + + WARN_ONCE(!task_monitor_slots[slot], "RV releasing unused task_monitor_slots: %d\n", + slot); + + task_monitor_count--; + task_monitor_slots[slot] = false; +} + +/* + * This section collects the monitor/ files and folders. + */ +static ssize_t monitor_enable_read_data(struct file *filp, char __user *user_buf, size_t count, + loff_t *ppos) +{ + struct rv_monitor_def *mdef = filp->private_data; + const char *buff; + + buff = mdef->monitor->enabled ? "1\n" : "0\n"; + + return simple_read_from_buffer(user_buf, count, ppos, buff, strlen(buff)+1); +} + +/* + * __rv_disable_monitor - disabled an enabled monitor + */ +static int __rv_disable_monitor(struct rv_monitor_def *mdef, bool sync) +{ + lockdep_assert_held(&rv_interface_lock); + + if (mdef->monitor->enabled) { + mdef->monitor->enabled = 0; + mdef->monitor->disable(); + + /* + * Wait for the execution of all events to finish. + * Otherwise, the data used by the monitor could + * be inconsistent. i.e., if the monitor is re-enabled. + */ + if (sync) + tracepoint_synchronize_unregister(); + return 1; + } + return 0; +} + +/** + * rv_disable_monitor - disable a given runtime monitor + * + * Returns 0 on success. + */ +int rv_disable_monitor(struct rv_monitor_def *mdef) +{ + __rv_disable_monitor(mdef, true); + return 0; +} + +/** + * rv_enable_monitor - enable a given runtime monitor + * + * Returns 0 on success, error otherwise. + */ +int rv_enable_monitor(struct rv_monitor_def *mdef) +{ + int retval; + + lockdep_assert_held(&rv_interface_lock); + + if (mdef->monitor->enabled) + return 0; + + retval = mdef->monitor->enable(); + + if (!retval) + mdef->monitor->enabled = 1; + + return retval; +} + +/* + * interface for enabling/disabling a monitor. + */ +static ssize_t monitor_enable_write_data(struct file *filp, const char __user *user_buf, + size_t count, loff_t *ppos) +{ + struct rv_monitor_def *mdef = filp->private_data; + int retval; + bool val; + + retval = kstrtobool_from_user(user_buf, count, &val); + if (retval) + return retval; + + retval = count; + + mutex_lock(&rv_interface_lock); + + if (val) + retval = rv_enable_monitor(mdef); + else + retval = rv_disable_monitor(mdef); + + mutex_unlock(&rv_interface_lock); + + return retval ? : count; +} + +static const struct file_operations interface_enable_fops = { + .open = simple_open, + .llseek = no_llseek, + .write = monitor_enable_write_data, + .read = monitor_enable_read_data, +}; + +/* + * Interface to read monitors description. + */ +static ssize_t monitor_desc_read_data(struct file *filp, char __user *user_buf, size_t count, + loff_t *ppos) +{ + struct rv_monitor_def *mdef = filp->private_data; + char buff[256]; + + memset(buff, 0, sizeof(buff)); + + snprintf(buff, sizeof(buff), "%s\n", mdef->monitor->description); + + return simple_read_from_buffer(user_buf, count, ppos, buff, strlen(buff) + 1); +} + +static const struct file_operations interface_desc_fops = { + .open = simple_open, + .llseek = no_llseek, + .read = monitor_desc_read_data, +}; + +/* + * During the registration of a monitor, this function creates + * the monitor dir, where the specific options of the monitor + * are exposed. + */ +static int create_monitor_dir(struct rv_monitor_def *mdef) +{ + struct dentry *root = get_monitors_root(); + const char *name = mdef->monitor->name; + struct dentry *tmp; + int retval; + + mdef->root_d = rv_create_dir(name, root); + if (!mdef->root_d) + return -ENOMEM; + + tmp = rv_create_file("enable", RV_MODE_WRITE, mdef->root_d, mdef, &interface_enable_fops); + if (!tmp) { + retval = -ENOMEM; + goto out_remove_root; + } + + tmp = rv_create_file("desc", RV_MODE_READ, mdef->root_d, mdef, &interface_desc_fops); + if (!tmp) { + retval = -ENOMEM; + goto out_remove_root; + } + + return 0; + +out_remove_root: + rv_remove(mdef->root_d); + return retval; +} + +/* + * Available/Enable monitor shared seq functions. + */ +static int monitors_show(struct seq_file *m, void *p) +{ + struct rv_monitor_def *mon_def = p; + + seq_printf(m, "%s\n", mon_def->monitor->name); + return 0; +} + +/* + * Used by the seq file operations at the end of a read + * operation. + */ +static void monitors_stop(struct seq_file *m, void *p) +{ + mutex_unlock(&rv_interface_lock); +} + +/* + * Available monitor seq functions. + */ +static void *available_monitors_start(struct seq_file *m, loff_t *pos) +{ + mutex_lock(&rv_interface_lock); + return seq_list_start(&rv_monitors_list, *pos); +} + +static void *available_monitors_next(struct seq_file *m, void *p, loff_t *pos) +{ + return seq_list_next(p, &rv_monitors_list, pos); +} + +/* + * Enable monitor seq functions. + */ +static void *enabled_monitors_next(struct seq_file *m, void *p, loff_t *pos) +{ + struct rv_monitor_def *m_def = p; + + (*pos)++; + + list_for_each_entry_continue(m_def, &rv_monitors_list, list) { + if (m_def->monitor->enabled) + return m_def; + } + + return NULL; +} + +static void *enabled_monitors_start(struct seq_file *m, loff_t *pos) +{ + struct rv_monitor_def *m_def; + loff_t l; + + mutex_lock(&rv_interface_lock); + + if (list_empty(&rv_monitors_list)) + return NULL; + + m_def = list_entry(&rv_monitors_list, struct rv_monitor_def, list); + + for (l = 0; l <= *pos; ) { + m_def = enabled_monitors_next(m, m_def, &l); + if (!m_def) + break; + } + + return m_def; +} + +/* + * available/enabled monitors seq definition. + */ +static const struct seq_operations available_monitors_seq_ops = { + .start = available_monitors_start, + .next = available_monitors_next, + .stop = monitors_stop, + .show = monitors_show +}; + +static const struct seq_operations enabled_monitors_seq_ops = { + .start = enabled_monitors_start, + .next = enabled_monitors_next, + .stop = monitors_stop, + .show = monitors_show +}; + +/* + * available_monitors interface. + */ +static int available_monitors_open(struct inode *inode, struct file *file) +{ + return seq_open(file, &available_monitors_seq_ops); +}; + +static const struct file_operations available_monitors_ops = { + .open = available_monitors_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release +}; + +/* + * enabled_monitors interface. + */ +static void disable_all_monitors(void) +{ + struct rv_monitor_def *mdef; + int enabled = 0; + + mutex_lock(&rv_interface_lock); + + list_for_each_entry(mdef, &rv_monitors_list, list) + enabled += __rv_disable_monitor(mdef, false); + + if (enabled) { + /* + * Wait for the execution of all events to finish. + * Otherwise, the data used by the monitor could + * be inconsistent. i.e., if the monitor is re-enabled. + */ + tracepoint_synchronize_unregister(); + } + + mutex_unlock(&rv_interface_lock); +} + +static int enabled_monitors_open(struct inode *inode, struct file *file) +{ + if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) + disable_all_monitors(); + + return seq_open(file, &enabled_monitors_seq_ops); +}; + +static ssize_t enabled_monitors_write(struct file *filp, const char __user *user_buf, + size_t count, loff_t *ppos) +{ + char buff[MAX_RV_MONITOR_NAME_SIZE + 2]; + struct rv_monitor_def *mdef; + int retval = -EINVAL; + bool enable = true; + char *ptr = buff; + int len; + + if (count < 1 || count > MAX_RV_MONITOR_NAME_SIZE + 1) + return -EINVAL; + + memset(buff, 0, sizeof(buff)); + + retval = simple_write_to_buffer(buff, sizeof(buff) - 1, ppos, user_buf, count); + if (retval < 0) + return -EFAULT; + + ptr = strim(buff); + + if (ptr[0] == '!') { + enable = false; + ptr++; + } + + len = strlen(ptr); + if (!len) + return count; + + mutex_lock(&rv_interface_lock); + + retval = -EINVAL; + + list_for_each_entry(mdef, &rv_monitors_list, list) { + if (strcmp(ptr, mdef->monitor->name) != 0) + continue; + + /* + * Monitor found! + */ + if (enable) + retval = rv_enable_monitor(mdef); + else + retval = rv_disable_monitor(mdef); + + if (!retval) + retval = count; + + break; + } + + mutex_unlock(&rv_interface_lock); + return retval; +} + +static const struct file_operations enabled_monitors_ops = { + .open = enabled_monitors_open, + .read = seq_read, + .write = enabled_monitors_write, + .llseek = seq_lseek, + .release = seq_release, +}; + +/* + * Monitoring on global switcher! + */ +static bool __read_mostly monitoring_on; + +/** + * rv_monitoring_on - checks if monitoring is on + * + * Returns 1 if on, 0 otherwise. + */ +bool rv_monitoring_on(void) +{ + /* Ensures that concurrent monitors read consistent monitoring_on */ + smp_rmb(); + return READ_ONCE(monitoring_on); +} + +/* + * monitoring_on general switcher. + */ +static ssize_t monitoring_on_read_data(struct file *filp, char __user *user_buf, + size_t count, loff_t *ppos) +{ + const char *buff; + + buff = rv_monitoring_on() ? "1\n" : "0\n"; + + return simple_read_from_buffer(user_buf, count, ppos, buff, strlen(buff) + 1); +} + +static void turn_monitoring_off(void) +{ + WRITE_ONCE(monitoring_on, false); + /* Ensures that concurrent monitors read consistent monitoring_on */ + smp_wmb(); +} + +static void reset_all_monitors(void) +{ + struct rv_monitor_def *mdef; + + list_for_each_entry(mdef, &rv_monitors_list, list) { + if (mdef->monitor->enabled) + mdef->monitor->reset(); + } +} + +static void turn_monitoring_on(void) +{ + WRITE_ONCE(monitoring_on, true); + /* Ensures that concurrent monitors read consistent monitoring_on */ + smp_wmb(); +} + +static void turn_monitoring_on_with_reset(void) +{ + lockdep_assert_held(&rv_interface_lock); + + if (rv_monitoring_on()) + return; + + /* + * Monitors might be out of sync with the system if events were not + * processed because of !rv_monitoring_on(). + * + * Reset all monitors, forcing a re-sync. + */ + reset_all_monitors(); + turn_monitoring_on(); +} + +static ssize_t monitoring_on_write_data(struct file *filp, const char __user *user_buf, + size_t count, loff_t *ppos) +{ + int retval; + bool val; + + retval = kstrtobool_from_user(user_buf, count, &val); + if (retval) + return retval; + + mutex_lock(&rv_interface_lock); + + if (val) + turn_monitoring_on_with_reset(); + else + turn_monitoring_off(); + + /* + * Wait for the execution of all events to finish + * before returning to user-space. + */ + tracepoint_synchronize_unregister(); + + mutex_unlock(&rv_interface_lock); + + return count; +} + +static const struct file_operations monitoring_on_fops = { + .open = simple_open, + .llseek = no_llseek, + .write = monitoring_on_write_data, + .read = monitoring_on_read_data, +}; + +static void destroy_monitor_dir(struct rv_monitor_def *mdef) +{ + rv_remove(mdef->root_d); +} + +/** + * rv_register_monitor - register a rv monitor. + * @monitor: The rv_monitor to be registered. + * + * Returns 0 if successful, error otherwise. + */ +int rv_register_monitor(struct rv_monitor *monitor) +{ + struct rv_monitor_def *r; + int retval = 0; + + if (strlen(monitor->name) >= MAX_RV_MONITOR_NAME_SIZE) { + pr_info("Monitor %s has a name longer than %d\n", monitor->name, + MAX_RV_MONITOR_NAME_SIZE); + return -1; + } + + mutex_lock(&rv_interface_lock); + + list_for_each_entry(r, &rv_monitors_list, list) { + if (strcmp(monitor->name, r->monitor->name) == 0) { + pr_info("Monitor %s is already registered\n", monitor->name); + retval = -1; + goto out_unlock; + } + } + + r = kzalloc(sizeof(struct rv_monitor_def), GFP_KERNEL); + if (!r) { + retval = -ENOMEM; + goto out_unlock; + } + + r->monitor = monitor; + + retval = create_monitor_dir(r); + if (retval) { + kfree(r); + goto out_unlock; + } + + list_add_tail(&r->list, &rv_monitors_list); + +out_unlock: + mutex_unlock(&rv_interface_lock); + return retval; +} + +/** + * rv_unregister_monitor - unregister a rv monitor. + * @monitor: The rv_monitor to be unregistered. + * + * Returns 0 if successful, error otherwise. + */ +int rv_unregister_monitor(struct rv_monitor *monitor) +{ + struct rv_monitor_def *ptr, *next; + + mutex_lock(&rv_interface_lock); + + list_for_each_entry_safe(ptr, next, &rv_monitors_list, list) { + if (strcmp(monitor->name, ptr->monitor->name) == 0) { + rv_disable_monitor(ptr); + list_del(&ptr->list); + destroy_monitor_dir(ptr); + } + } + + mutex_unlock(&rv_interface_lock); + return 0; +} + +int __init rv_init_interface(void) +{ + struct dentry *tmp; + + rv_root.root_dir = rv_create_dir("rv", NULL); + if (!rv_root.root_dir) + goto out_err; + + rv_root.monitors_dir = rv_create_dir("monitors", rv_root.root_dir); + if (!rv_root.monitors_dir) + goto out_err; + + tmp = rv_create_file("available_monitors", RV_MODE_READ, rv_root.root_dir, NULL, + &available_monitors_ops); + if (!tmp) + goto out_err; + + tmp = rv_create_file("enabled_monitors", RV_MODE_WRITE, rv_root.root_dir, NULL, + &enabled_monitors_ops); + if (!tmp) + goto out_err; + + tmp = rv_create_file("monitoring_on", RV_MODE_WRITE, rv_root.root_dir, NULL, + &monitoring_on_fops); + if (!tmp) + goto out_err; + + turn_monitoring_on(); + + return 0; + +out_err: + rv_remove(rv_root.root_dir); + printk(KERN_ERR "RV: Error while creating the RV interface\n"); + return 1; +} diff --git a/kernel/trace/rv/rv.h b/kernel/trace/rv/rv.h new file mode 100644 index 000000000000..50014aa224a7 --- /dev/null +++ b/kernel/trace/rv/rv.h @@ -0,0 +1,33 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include + +struct rv_interface { + struct dentry *root_dir; + struct dentry *monitors_dir; +}; + +#include "../trace.h" +#include +#include + +#define RV_MODE_WRITE TRACE_MODE_WRITE +#define RV_MODE_READ TRACE_MODE_READ + +#define rv_create_dir tracefs_create_dir +#define rv_create_file tracefs_create_file +#define rv_remove tracefs_remove + +#define MAX_RV_MONITOR_NAME_SIZE 32 + +extern struct mutex rv_interface_lock; + +struct rv_monitor_def { + struct list_head list; + struct rv_monitor *monitor; + struct dentry *root_d; + bool task_monitor; +}; + +struct dentry *get_monitors_root(void); +int rv_disable_monitor(struct rv_monitor_def *mdef); +int rv_enable_monitor(struct rv_monitor_def *mdef); diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b8dd54627075..062423371741 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -9772,6 +9772,8 @@ static __init int tracer_init_tracefs(void) tracer_init_tracefs_work_func(NULL); } + rv_init_interface(); + return 0; } diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index ff816fb41e48..900e75d96c84 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -2005,4 +2005,13 @@ struct trace_min_max_param { extern const struct file_operations trace_min_max_fops; +#ifdef CONFIG_RV +extern int rv_init_interface(void); +#else +static inline int rv_init_interface(void) +{ + return 0; +} +#endif + #endif /* _LINUX_KERNEL_TRACE_H */ From patchwork Fri Jul 29 09:38:41 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932244 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 81A7CC3F6B0 for ; Fri, 29 Jul 2022 09:39:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235647AbiG2JjX (ORCPT ); Fri, 29 Jul 2022 05:39:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37356 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235631AbiG2JjW (ORCPT ); Fri, 29 Jul 2022 05:39:22 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 03B7C85FB0; Fri, 29 Jul 2022 02:39:20 -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 ams.source.kernel.org (Postfix) with ESMTPS id 834B2B8270F; Fri, 29 Jul 2022 09:39:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ADCD1C43140; Fri, 29 Jul 2022 09:39:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087557; bh=4h37GF9kAL2W6fAX52BEMa40Mw3q9sDwQ7Za04Gy2e0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L8UOcKQa/xMeWTVix3e3G6vLt34Is4KOmwZe6Y0M/YzCtfSaZ+3so3agxpfsbqfju 5XzOxjcJF6h2VfOLuFS9LHDpwr4xXUVbjZotZiYujv8huHU2C+VvMBYD49My2tPlGw J4JVJznh0Tr6mu6UdvB8XKXDH1biTn0QVrdUGRMMm5uTtrH+yN1px3ieyyS1RGgcWN zCCFsDmyTw+C4F27AcF+iA2fle0Ewhg8pdldNMk2A7jeBBa0t2rutmNor7WfwNX4xa nqsrGBfclQy8oo0BpITeymWgiJ5RS8UvQ51FtbMfq+UFmPBpYl5ddPlGbxKYQ5jNG1 w/xC+XkNuXVBw== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 02/16] rv: Add runtime reactors interface Date: Fri, 29 Jul 2022 11:38:41 +0200 Message-Id: <1794eb994637457bdeaa6bad0b8263d2f7eece0c.1659052063.git.bristot@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org A runtime monitor can cause a reaction to the detection of an exception on the model's execution. By default, the monitors have tracing reactions, printing the monitor output via tracepoints. But other reactions can be added (on-demand) via this interface. The user interface resembles the kernel tracing interface and presents these files: "available_reactors" - Reading shows the available reactors, one per line. For example: # cat available_reactors nop panic printk "reacting_on" - It is an on/off general switch for reactors, disabling all reactions. "monitors/MONITOR/reactors" - List available reactors, with the select reaction for the given MONITOR inside []. The default one is the nop (no operation) reactor. - Writing the name of a reactor enables it to the given MONITOR. For example: # cat monitors/wip/reactors [nop] panic printk # echo panic > monitors/wip/reactors # cat monitors/wip/reactors nop [panic] printk Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- include/linux/rv.h | 17 ++ kernel/trace/rv/Kconfig | 11 + kernel/trace/rv/Makefile | 1 + kernel/trace/rv/rv.c | 9 + kernel/trace/rv/rv.h | 35 +++ kernel/trace/rv/rv_reactors.c | 508 ++++++++++++++++++++++++++++++++++ 6 files changed, 581 insertions(+) create mode 100644 kernel/trace/rv/rv_reactors.c diff --git a/include/linux/rv.h b/include/linux/rv.h index d8fa9e8be94a..dcce56987cf7 100644 --- a/include/linux/rv.h +++ b/include/linux/rv.h @@ -24,6 +24,14 @@ union rv_task_monitor { }; +#ifdef CONFIG_RV_REACTORS +struct rv_reactor { + const char *name; + const char *description; + void (*react)(char *msg); +}; +#endif + struct rv_monitor { const char *name; const char *description; @@ -31,6 +39,9 @@ struct rv_monitor { int (*enable)(void); void (*disable)(void); void (*reset)(void); +#ifdef CONFIG_RV_REACTORS + void (*react)(char *msg); +#endif }; bool rv_monitoring_on(void); @@ -39,5 +50,11 @@ int rv_register_monitor(struct rv_monitor *monitor); int rv_get_task_monitor_slot(void); void rv_put_task_monitor_slot(int slot); +#ifdef CONFIG_RV_REACTORS +bool rv_reacting_on(void); +int rv_unregister_reactor(struct rv_reactor *reactor); +int rv_register_reactor(struct rv_reactor *reactor); +#endif /* CONFIG_RV_REACTORS */ + #endif /* CONFIG_RV */ #endif /* _LINUX_RV_H */ diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig index 6d127cdb00dd..3eb5d48ab4f6 100644 --- a/kernel/trace/rv/Kconfig +++ b/kernel/trace/rv/Kconfig @@ -10,3 +10,14 @@ menuconfig RV theorem proving). RV works by analyzing the trace of the system's actual execution, comparing it against a formal specification of the system behavior. + +config RV_REACTORS + bool "Runtime verification reactors" + default y + depends on RV + help + Enables the online runtime verification reactors. A runtime + monitor can cause a reaction to the detection of an exception + on the model's execution. By default, the monitors have + tracing reactions, printing the monitor output via tracepoints, + but other reactions can be added (on-demand) via this interface. diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile index fd995379df67..8944274d9b41 100644 --- a/kernel/trace/rv/Makefile +++ b/kernel/trace/rv/Makefile @@ -1,3 +1,4 @@ # SPDX-License-Identifier: GPL-2.0 obj-$(CONFIG_RV) += rv.o +obj-$(CONFIG_RV_REACTORS) += rv_reactors.o diff --git a/kernel/trace/rv/rv.c b/kernel/trace/rv/rv.c index 731cc961cc70..45cf64eb2600 100644 --- a/kernel/trace/rv/rv.c +++ b/kernel/trace/rv/rv.c @@ -353,6 +353,10 @@ static int create_monitor_dir(struct rv_monitor_def *mdef) goto out_remove_root; } + retval = reactor_populate_monitor(mdef); + if (retval) + goto out_remove_root; + return 0; out_remove_root: @@ -669,6 +673,7 @@ static const struct file_operations monitoring_on_fops = { static void destroy_monitor_dir(struct rv_monitor_def *mdef) { + reactor_cleanup_monitor(mdef); rv_remove(mdef->root_d); } @@ -747,6 +752,7 @@ int rv_unregister_monitor(struct rv_monitor *monitor) int __init rv_init_interface(void) { struct dentry *tmp; + int retval; rv_root.root_dir = rv_create_dir("rv", NULL); if (!rv_root.root_dir) @@ -770,6 +776,9 @@ int __init rv_init_interface(void) &monitoring_on_fops); if (!tmp) goto out_err; + retval = init_rv_reactors(rv_root.root_dir); + if (retval) + goto out_err; turn_monitoring_on(); diff --git a/kernel/trace/rv/rv.h b/kernel/trace/rv/rv.h index 50014aa224a7..db6cb0913dbd 100644 --- a/kernel/trace/rv/rv.h +++ b/kernel/trace/rv/rv.h @@ -18,16 +18,51 @@ struct rv_interface { #define rv_remove tracefs_remove #define MAX_RV_MONITOR_NAME_SIZE 32 +#define MAX_RV_REACTOR_NAME_SIZE 32 extern struct mutex rv_interface_lock; +#ifdef CONFIG_RV_REACTORS +struct rv_reactor_def { + struct list_head list; + struct rv_reactor *reactor; + /* protected by the monitor interface lock */ + int counter; +}; +#endif + struct rv_monitor_def { struct list_head list; struct rv_monitor *monitor; struct dentry *root_d; +#ifdef CONFIG_RV_REACTORS + struct rv_reactor_def *rdef; + bool reacting; +#endif bool task_monitor; }; struct dentry *get_monitors_root(void); int rv_disable_monitor(struct rv_monitor_def *mdef); int rv_enable_monitor(struct rv_monitor_def *mdef); + +#ifdef CONFIG_RV_REACTORS +int reactor_populate_monitor(struct rv_monitor_def *mdef); +void reactor_cleanup_monitor(struct rv_monitor_def *mdef); +int init_rv_reactors(struct dentry *root_dir); +#else +static inline int reactor_populate_monitor(struct rv_monitor_def *mdef) +{ + return 0; +} + +static inline void reactor_cleanup_monitor(struct rv_monitor_def *mdef) +{ + return; +} + +static inline int init_rv_reactors(struct dentry *root_dir) +{ + return 0; +} +#endif diff --git a/kernel/trace/rv/rv_reactors.c b/kernel/trace/rv/rv_reactors.c new file mode 100644 index 000000000000..a6522c196382 --- /dev/null +++ b/kernel/trace/rv/rv_reactors.c @@ -0,0 +1,508 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira + * + * Runtime reactor interface. + * + * A runtime monitor can cause a reaction to the detection of an + * exception on the model's execution. By default, the monitors have + * tracing reactions, printing the monitor output via tracepoints. + * But other reactions can be added (on-demand) via this interface. + * + * == Registering reactors == + * + * The struct rv_reactor defines a callback function to be executed + * in case of a model exception happens. The callback function + * receives a message to be (optionally) printed before executing + * the reaction. + * + * A RV reactor is registered via: + * int rv_register_reactor(struct rv_reactor *reactor) + * And unregistered via: + * int rv_unregister_reactor(struct rv_reactor *reactor) + * + * These functions are exported to modules, enabling reactors to be + * dynamically loaded. + * + * == User interface == + * + * The user interface resembles the kernel tracing interface and + * presents these files: + * + * "available_reactors" + * - List the available reactors, one per line. + * + * For example: + * # cat available_reactors + * nop + * panic + * printk + * + * "reacting_on" + * - It is an on/off general switch for reactors, disabling + * all reactions. + * + * "monitors/MONITOR/reactors" + * - List available reactors, with the select reaction for the given + * MONITOR inside []. The default one is the nop (no operation) + * reactor. + * - Writing the name of an reactor enables it to the given + * MONITOR. + * + * For example: + * # cat monitors/wip/reactors + * [nop] + * panic + * printk + * # echo panic > monitors/wip/reactors + * # cat monitors/wip/reactors + * nop + * [panic] + * printk + */ + +#include + +#include "rv.h" + +/* + * Interface for the reactor register. + */ +static LIST_HEAD(rv_reactors_list); + +static struct rv_reactor_def *get_reactor_rdef_by_name(char *name) +{ + struct rv_reactor_def *r; + + list_for_each_entry(r, &rv_reactors_list, list) { + if (strcmp(name, r->reactor->name) == 0) + return r; + } + return NULL; +} + +/* + * Available reactors seq functions. + */ +static int reactors_show(struct seq_file *m, void *p) +{ + struct rv_reactor_def *rea_def = p; + + seq_printf(m, "%s\n", rea_def->reactor->name); + return 0; +} + +static void reactors_stop(struct seq_file *m, void *p) +{ + mutex_unlock(&rv_interface_lock); +} + +static void *reactors_start(struct seq_file *m, loff_t *pos) +{ + mutex_lock(&rv_interface_lock); + return seq_list_start(&rv_reactors_list, *pos); +} + +static void *reactors_next(struct seq_file *m, void *p, loff_t *pos) +{ + return seq_list_next(p, &rv_reactors_list, pos); +} + +/* + * available_reactors seq definition. + */ +static const struct seq_operations available_reactors_seq_ops = { + .start = reactors_start, + .next = reactors_next, + .stop = reactors_stop, + .show = reactors_show +}; + +/* + * available_reactors interface. + */ +static int available_reactors_open(struct inode *inode, struct file *file) +{ + return seq_open(file, &available_reactors_seq_ops); +}; + +static const struct file_operations available_reactors_ops = { + .open = available_reactors_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release +}; + +/* + * Monitor's reactor file. + */ +static int monitor_reactor_show(struct seq_file *m, void *p) +{ + struct rv_monitor_def *mdef = m->private; + struct rv_reactor_def *rdef = p; + + if (mdef->rdef == rdef) + seq_printf(m, "[%s]\n", rdef->reactor->name); + else + seq_printf(m, "%s\n", rdef->reactor->name); + return 0; +} + +/* + * available_reactors seq definition. + */ +static const struct seq_operations monitor_reactors_seq_ops = { + .start = reactors_start, + .next = reactors_next, + .stop = reactors_stop, + .show = monitor_reactor_show +}; + +static void monitor_swap_reactors(struct rv_monitor_def *mdef, struct rv_reactor_def *rdef, + bool reacting) +{ + bool monitor_enabled; + + /* nothing to do */ + if (mdef->rdef == rdef) + return; + + monitor_enabled = mdef->monitor->enabled; + if (monitor_enabled) + rv_disable_monitor(mdef); + + /* swap reactor's usage */ + mdef->rdef->counter--; + rdef->counter++; + + mdef->rdef = rdef; + mdef->reacting = reacting; + mdef->monitor->react = rdef->reactor->react; + + if (monitor_enabled) + rv_enable_monitor(mdef); +} + +static ssize_t +monitor_reactors_write(struct file *file, const char __user *user_buf, + size_t count, loff_t *ppos) +{ + char buff[MAX_RV_REACTOR_NAME_SIZE + 2]; + struct rv_monitor_def *mdef; + struct rv_reactor_def *rdef; + struct seq_file *seq_f; + int retval = -EINVAL; + bool enable; + char *ptr; + int len; + + if (count < 1 || count > MAX_RV_REACTOR_NAME_SIZE + 1) + return -EINVAL; + + memset(buff, 0, sizeof(buff)); + + retval = simple_write_to_buffer(buff, sizeof(buff) - 1, ppos, user_buf, count); + if (retval < 0) + return -EFAULT; + + ptr = strim(buff); + + len = strlen(ptr); + if (!len) + return count; + + /* + * See monitor_reactors_open() + */ + seq_f = file->private_data; + mdef = seq_f->private; + + mutex_lock(&rv_interface_lock); + + retval = -EINVAL; + + list_for_each_entry(rdef, &rv_reactors_list, list) { + if (strcmp(ptr, rdef->reactor->name) != 0) + continue; + + if (rdef == get_reactor_rdef_by_name("nop")) + enable = false; + else + enable = true; + + monitor_swap_reactors(mdef, rdef, enable); + + retval = count; + break; + } + + mutex_unlock(&rv_interface_lock); + + return retval; +} + +/* + * available_reactors interface. + */ +static int monitor_reactors_open(struct inode *inode, struct file *file) +{ + struct rv_monitor_def *mdef = inode->i_private; + struct seq_file *seq_f; + int ret; + + ret = seq_open(file, &monitor_reactors_seq_ops); + if (ret < 0) + return ret; + + /* + * seq_open stores the seq_file on the file->private data. + */ + seq_f = file->private_data; + + /* + * Copy the create file "private" data to the seq_file private data. + */ + seq_f->private = mdef; + + return 0; +}; + +static const struct file_operations monitor_reactors_ops = { + .open = monitor_reactors_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release, + .write = monitor_reactors_write +}; + +static int __rv_register_reactor(struct rv_reactor *reactor) +{ + struct rv_reactor_def *r; + + list_for_each_entry(r, &rv_reactors_list, list) { + if (strcmp(reactor->name, r->reactor->name) == 0) { + pr_info("Reactor %s is already registered\n", reactor->name); + return -EINVAL; + } + } + + r = kzalloc(sizeof(struct rv_reactor_def), GFP_KERNEL); + if (!r) + return -ENOMEM; + + r->reactor = reactor; + r->counter = 0; + + list_add_tail(&r->list, &rv_reactors_list); + + return 0; +} + +/** + * rv_register_reactor - register a rv reactor. + * @reactor: The rv_reactor to be registered. + * + * Returns 0 if successful, error otherwise. + */ +int rv_register_reactor(struct rv_reactor *reactor) +{ + int retval = 0; + + if (strlen(reactor->name) >= MAX_RV_REACTOR_NAME_SIZE) { + pr_info("Reactor %s has a name longer than %d\n", + reactor->name, MAX_RV_MONITOR_NAME_SIZE); + return -EINVAL; + } + + mutex_lock(&rv_interface_lock); + retval = __rv_register_reactor(reactor); + mutex_unlock(&rv_interface_lock); + return retval; +} + +/** + * rv_unregister_reactor - unregister a rv reactor. + * @reactor: The rv_reactor to be unregistered. + * + * Returns 0 if successful, error otherwise. + */ +int rv_unregister_reactor(struct rv_reactor *reactor) +{ + struct rv_reactor_def *ptr, *next; + + mutex_lock(&rv_interface_lock); + + list_for_each_entry_safe(ptr, next, &rv_reactors_list, list) { + if (strcmp(reactor->name, ptr->reactor->name) == 0) { + + if (!ptr->counter) { + list_del(&ptr->list); + } else { + printk(KERN_WARNING + "rv: the rv_reactor %s is in use by %d monitor(s)\n", + ptr->reactor->name, ptr->counter); + printk(KERN_WARNING "rv: the rv_reactor %s cannot be removed\n", + ptr->reactor->name); + return -EBUSY; + } + } + } + + mutex_unlock(&rv_interface_lock); + return 0; +} + +/* + * reacting_on interface. + */ +static bool __read_mostly reacting_on; + +/** + * rv_reacting_on - checks if reacting is on + * + * Returns 1 if on, 0 otherwise. + */ +bool rv_reacting_on(void) +{ + /* Ensures that concurrent monitors read consistent reacting_on */ + smp_rmb(); + return READ_ONCE(reacting_on); +} + +static ssize_t reacting_on_read_data(struct file *filp, + char __user *user_buf, + size_t count, loff_t *ppos) +{ + char *buff; + + buff = rv_reacting_on() ? "1\n" : "0\n"; + + return simple_read_from_buffer(user_buf, count, ppos, buff, strlen(buff)+1); +} + +static void turn_reacting_off(void) +{ + WRITE_ONCE(reacting_on, false); + /* Ensures that concurrent monitors read consistent reacting_on */ + smp_wmb(); +} + +static void turn_reacting_on(void) +{ + WRITE_ONCE(reacting_on, true); + /* Ensures that concurrent monitors read consistent reacting_on */ + smp_wmb(); +} + +static ssize_t reacting_on_write_data(struct file *filp, const char __user *user_buf, + size_t count, loff_t *ppos) +{ + int retval; + bool val; + + retval = kstrtobool_from_user(user_buf, count, &val); + if (retval) + return retval; + + mutex_lock(&rv_interface_lock); + + if (val) + turn_reacting_on(); + else + turn_reacting_off(); + + /* + * Wait for the execution of all events to finish + * before returning to user-space. + */ + tracepoint_synchronize_unregister(); + + mutex_unlock(&rv_interface_lock); + + return count; +} + +static const struct file_operations reacting_on_fops = { + .open = simple_open, + .llseek = no_llseek, + .write = reacting_on_write_data, + .read = reacting_on_read_data, +}; + +/** + * reactor_populate_monitor - creates per monitor reactors file + * @mdef: monitor's definition. + * + * Returns 0 if successful, error otherwise. + */ +int reactor_populate_monitor(struct rv_monitor_def *mdef) +{ + struct dentry *tmp; + + tmp = rv_create_file("reactors", RV_MODE_WRITE, mdef->root_d, mdef, &monitor_reactors_ops); + if (!tmp) + return -ENOMEM; + + /* + * Configure as the rv_nop reactor. + */ + mdef->rdef = get_reactor_rdef_by_name("nop"); + mdef->rdef->counter++; + mdef->reacting = false; + + return 0; +} + +/** + * reactor_cleanup_monitor - cleanup a monitor reference + * @mdef: monitor's definition. + */ +void reactor_cleanup_monitor(struct rv_monitor_def *mdef) +{ + lockdep_assert_held(&rv_interface_lock); + mdef->rdef->counter--; + WARN_ON_ONCE(mdef->rdef->counter < 0); +} + +/* + * Nop reactor register + */ +static void rv_nop_reaction(char *msg) +{ +} + +static struct rv_reactor rv_nop = { + .name = "nop", + .description = "no-operation reactor: do nothing.", + .react = rv_nop_reaction +}; + +int init_rv_reactors(struct dentry *root_dir) +{ + struct dentry *available, *reacting; + int retval; + + available = rv_create_file("available_reactors", RV_MODE_READ, root_dir, NULL, + &available_reactors_ops); + if (!available) + goto out_err; + + reacting = rv_create_file("reacting_on", RV_MODE_WRITE, root_dir, NULL, &reacting_on_fops); + if (!reacting) + goto rm_available; + + retval = __rv_register_reactor(&rv_nop); + if (retval) + goto rm_reacting; + + turn_reacting_on(); + + return 0; + +rm_reacting: + rv_remove(reacting); +rm_available: + rv_remove(available); +out_err: + return -ENOMEM; +} From patchwork Fri Jul 29 09:38:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932245 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 8496AC00144 for ; Fri, 29 Jul 2022 09:39:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235691AbiG2Jjd (ORCPT ); Fri, 29 Jul 2022 05:39:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37376 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235655AbiG2JjY (ORCPT ); Fri, 29 Jul 2022 05:39:24 -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 2E6734F674; Fri, 29 Jul 2022 02:39:23 -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 CA17561D43; Fri, 29 Jul 2022 09:39:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF4CEC43141; Fri, 29 Jul 2022 09:39:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087562; bh=oWw25mtkJXkfmoetD7cNHKyHoDEVZWd1NhnSPh98QnQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=V35CUiW/D6XVNnoOIq+dlMbi3L8jwnrxMBCj1IXuAAwGXqW+lcm4cEZFTRUSyrasr uSX6FveXUo5kzghM3MbxBdhWaB8QULn3DIOBuEytU5VumYtH+sbRaGVZE+7WVvNMSp 6bvu/b4+sK1MZFwbyjUoWZLqa97DChSZ1rdeSiIQv6qqROPfpx21E5+MrVB03U9/fQ XZyUoPi+EpYWI1dlLmRD0DXEqFUnp3MaB51od80MJs+c1/YwpNstcUZ3AAAbkrFiUm sDZkcXmhMbegMnbGVHPfZwRHJi2DtZVn8h2z0SmJ3780ViATpuV8RtNOuwW0C7InRU AndFiN46Z9Kkg== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 03/16] rv/include: Add helper functions for deterministic automata Date: Fri, 29 Jul 2022 11:38:42 +0200 Message-Id: <563234f2bfa84b540f60cf9e39c2d9f0eea95a55.1659052063.git.bristot@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Formally, a deterministic automaton, denoted by G, is defined as a quintuple: G = { X, E, f, x_0, X_m } where: - X is the set of states; - E is the finite set of events; - x_0 is the initial state; - X_m (subset of X) is the set of marked states. - f : X x E -> X $ is the transition function. It defines the state transition in the occurrence of a event from E in the state X. In the special case of deterministic automata, the occurrence of the event in E in a state in X has a deterministic next state from X. An automaton can also be represented using a graphical format of vertices (nodes) and edges. The open-source tool Graphviz can produce this graphic format using the (textual) DOT language as the source code. The dot2c tool presented in this paper: De Oliveira, Daniel Bristot; Cucinotta, Tommaso; De Oliveira, Romulo Silva. Efficient formal verification for the Linux kernel. In: International Conference on Software Engineering and Formal Methods. Springer, Cham, 2019. p. 315-332. Translates a deterministic automaton in the DOT format into a C source code representation that to be used for monitoring. This header file implements helper functions to facilitate the usage of the C output from dot2c/k for monitoring. Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- include/rv/automata.h | 75 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 include/rv/automata.h diff --git a/include/rv/automata.h b/include/rv/automata.h new file mode 100644 index 000000000000..eb9e636809a0 --- /dev/null +++ b/include/rv/automata.h @@ -0,0 +1,75 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira + * + * Deterministic automata helper functions, to be used with the automata + * models in C generated by the dot2k tool. + */ + +/* + * DECLARE_AUTOMATA_HELPERS - define a set of helper functions for automata + * + * Define a set of helper functions for automata. The 'name' argument is used + * as suffix for the functions and data. These functions will handle automaton + * with data type 'type'. + */ +#define DECLARE_AUTOMATA_HELPERS(name, type) \ + \ +/* \ + * model_get_state_name_##name - return the (string) name of the given state \ + */ \ +static char *model_get_state_name_##name(enum states_##name state) \ +{ \ + if ((state < 0) || (state >= state_max_##name)) \ + return "INVALID"; \ + \ + return automaton_##name.state_names[state]; \ +} \ + \ +/* \ + * model_get_event_name_##name - return the (string) name of the given event \ + */ \ +static char *model_get_event_name_##name(enum events_##name event) \ +{ \ + if ((event < 0) || (event >= event_max_##name)) \ + return "INVALID"; \ + \ + return automaton_##name.event_names[event]; \ +} \ + \ +/* \ + * model_get_initial_state_##name - return the automaton's initial state \ + */ \ +static inline type model_get_initial_state_##name(void) \ +{ \ + return automaton_##name.initial_state; \ +} \ + \ +/* \ + * model_get_next_state_##name - process an automaton event occurrence \ + * \ + * Given the current state (curr_state) and the event (event), returns \ + * the next state, or INVALID_STATE in case of error. \ + */ \ +static inline type model_get_next_state_##name(enum states_##name curr_state, \ + enum events_##name event) \ +{ \ + if ((curr_state < 0) || (curr_state >= state_max_##name)) \ + return INVALID_STATE; \ + \ + if ((event < 0) || (event >= event_max_##name)) \ + return INVALID_STATE; \ + \ + return automaton_##name.function[curr_state][event]; \ +} \ + \ +/* \ + * model_is_final_state_##name - check if the given state is a final state \ + */ \ +static inline bool model_is_final_state_##name(enum states_##name state) \ +{ \ + if ((state < 0) || (state >= state_max_##name)) \ + return 0; \ + \ + return automaton_##name.final_states[state]; \ +} From patchwork Fri Jul 29 09:38:43 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932246 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 BE9C9C19F2B for ; Fri, 29 Jul 2022 09:39:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235701AbiG2Jjf (ORCPT ); Fri, 29 Jul 2022 05:39:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37586 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235631AbiG2Jjd (ORCPT ); Fri, 29 Jul 2022 05:39:33 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 59BAC85FBF; Fri, 29 Jul 2022 02:39:30 -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 ams.source.kernel.org (Postfix) with ESMTPS id A6782B826F8; Fri, 29 Jul 2022 09:39:28 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B0C57C43145; Fri, 29 Jul 2022 09:39:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087567; bh=mOUczc0ARivy6XevmPDa4Al3Gtuy+OhwFa5ffbOuu/4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gJ+iV7v86/1yYGYeFNjdUa04r1kznl3GDO7+lxXL+N0klsh/ShzPVSVgsC1dO9NC6 QeZ4iGpJcX1JJownn/EJc5mNIFwsXXNJsrsBfTwX6RIOo2VrCJcTzmOwyt7vQ+1wsS QDvk+88QFuUxa9cZOr6KbowrX/7+Au2rza5lnWcZj4DBrKULSyEuFDs820I13O9TxQ ssk68V4LxSM6jV7RcmwJYCW7nI7u8tNazpT5AOq2G8hnMxzkBXqwd8xSZCCzLlZ1tj KMKwyF44CjqphoXVL8o9h4XojcyVZMoqiOOl96MyMJsbQQVlbXpS2/NK5KVwMRaIbO QqOlWMb1PcmpA== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 04/16] rv/include: Add deterministic automata monitor definition via C macros Date: Fri, 29 Jul 2022 11:38:43 +0200 Message-Id: <51b0bf425a281e226dfeba7401d2115d6091f84e.1659052063.git.bristot@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org In Linux terms, the runtime verification monitors are encapsulated inside the "RV monitor" abstraction. The "RV monitor" includes a set of instances of the monitor (per-cpu monitor, per-task monitor, and so on), the helper functions that glue the monitor to the system reference model, and the trace output as a reaction for event parsing and exceptions, as depicted below: Linux +----- RV Monitor ----------------------------------+ Formal Realm | | Realm +-------------------+ +----------------+ +-----------------+ | Linux kernel | | Monitor | | Reference | | Tracing | -> | Instance(s) | <- | Model | | (instrumentation) | | (verification) | | (specification) | +-------------------+ +----------------+ +-----------------+ | | | | V | | +----------+ | | | Reaction | | | +--+--+--+-+ | | | | | | | | | +-> trace output ? | +------------------------|--|----------------------+ | +----> panic ? +-------> Add the rv/da_monitor.h, enabling automatic code generation for the *Monitor Instance(s)* using C macros, and code to support it. The benefits of the usage of macro for monitor synthesis are 3-fold as it: - Reduces the code duplication; - Facilitates the bug fix/improvement; - Avoids the case of developers changing the core of the monitor code to manipulate the model in a (let's say) non-standard way. This initial implementation presents three different types of monitor instances: - DECLARE_DA_MON_GLOBAL(name, type) - DECLARE_DA_MON_PER_CPU(name, type) - DECLARE_DA_MON_PER_TASK(name, type) The first declares the functions for a global deterministic automata monitor, the second for monitors with per-cpu instances, and the third with per-task instances. Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- include/linux/rv.h | 10 + include/rv/da_monitor.h | 541 ++++++++++++++++++++++++++++++++++++++ include/trace/events/rv.h | 120 +++++++++ kernel/fork.c | 14 + kernel/trace/rv/Kconfig | 11 + kernel/trace/rv/rv.c | 5 + 6 files changed, 701 insertions(+) create mode 100644 include/rv/da_monitor.h create mode 100644 include/trace/events/rv.h diff --git a/include/linux/rv.h b/include/linux/rv.h index dcce56987cf7..8883b41d88ec 100644 --- a/include/linux/rv.h +++ b/include/linux/rv.h @@ -7,7 +7,16 @@ #ifndef _LINUX_RV_H #define _LINUX_RV_H +#define MAX_DA_NAME_LEN 24 + #ifdef CONFIG_RV +/* + * Deterministic automaton per-object variables. + */ +struct da_monitor { + bool monitoring; + unsigned int curr_state; +}; /* * Per-task RV monitors count. Nowadays fixed in RV_PER_TASK_MONITORS. @@ -22,6 +31,7 @@ * Futher monitor types are expected, so make this a union. */ union rv_task_monitor { + struct da_monitor da_mon; }; #ifdef CONFIG_RV_REACTORS diff --git a/include/rv/da_monitor.h b/include/rv/da_monitor.h new file mode 100644 index 000000000000..001bc298289f --- /dev/null +++ b/include/rv/da_monitor.h @@ -0,0 +1,541 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira + * + * Deterministic automata (DA) monitor functions, to be used together + * with automata models in C generated by the dot2k tool. + * + * The dot2k tool is available at tools/verification/dot2k/ + */ + +#include +#include +#include + +#ifdef CONFIG_RV_REACTORS + +#define DECLARE_RV_REACTING_HELPERS(name, type) \ +static char REACT_MSG_##name[1024]; \ + \ +static inline char *format_react_msg_##name(type curr_state, type event) \ +{ \ + snprintf(REACT_MSG_##name, 1024, \ + "rv: monitor %s does not allow event %s on state %s\n", \ + #name, \ + model_get_event_name_##name(event), \ + model_get_state_name_##name(curr_state)); \ + return REACT_MSG_##name; \ +} \ + \ +static void cond_react_##name(char *msg) \ +{ \ + if (rv_##name.react) \ + rv_##name.react(msg); \ +} \ + \ +static bool rv_reacting_on_##name(void) \ +{ \ + return rv_reacting_on(); \ +} + +#else /* CONFIG_RV_REACTOR */ + +#define DECLARE_RV_REACTING_HELPERS(name, type) \ +static inline char *format_react_msg_##name(type curr_state, type event) \ +{ \ + return NULL; \ +} \ + \ +static void cond_react_##name(char *msg) \ +{ \ + return; \ +} \ + \ +static bool rv_reacting_on_##name(void) \ +{ \ + return 0; \ +} +#endif + +/* + * Generic helpers for all types of deterministic automata monitors. + */ +#define DECLARE_DA_MON_GENERIC_HELPERS(name, type) \ + \ +DECLARE_RV_REACTING_HELPERS(name, type) \ + \ +/* \ + * da_monitor_reset_##name - reset a monitor and setting it to init state \ + */ \ +static inline void da_monitor_reset_##name(struct da_monitor *da_mon) \ +{ \ + da_mon->monitoring = 0; \ + da_mon->curr_state = model_get_initial_state_##name(); \ +} \ + \ +/* \ + * da_monitor_curr_state_##name - return the current state \ + */ \ +static inline type da_monitor_curr_state_##name(struct da_monitor *da_mon) \ +{ \ + return da_mon->curr_state; \ +} \ + \ +/* \ + * da_monitor_set_state_##name - set the new current state \ + */ \ +static inline void \ +da_monitor_set_state_##name(struct da_monitor *da_mon, enum states_##name state) \ +{ \ + da_mon->curr_state = state; \ +} \ + \ +/* \ + * da_monitor_start_##name - start monitoring \ + * \ + * The monitor will ignore all events until monitoring is set to true. This \ + * function needs to be called to tell the monitor to start monitoring. \ + */ \ +static inline void da_monitor_start_##name(struct da_monitor *da_mon) \ +{ \ + da_mon->curr_state = model_get_initial_state_##name(); \ + da_mon->monitoring = 1; \ +} \ + \ +/* \ + * da_monitoring_##name - returns true if the monitor is processing events \ + */ \ +static inline bool da_monitoring_##name(struct da_monitor *da_mon) \ +{ \ + return da_mon->monitoring; \ +} \ + \ +/* \ + * da_monitor_enabled_##name - checks if the monitor is enabled \ + */ \ +static inline bool da_monitor_enabled_##name(void) \ +{ \ + /* global switch */ \ + if (unlikely(!rv_monitoring_on())) \ + return 0; \ + \ + /* monitor enabled */ \ + if (unlikely(!rv_##name.enabled)) \ + return 0; \ + \ + return 1; \ +} \ + \ +/* \ + * da_monitor_handling_event_##name - checks if the monitor is ready to handle events \ + */ \ +static inline bool da_monitor_handling_event_##name(struct da_monitor *da_mon) \ +{ \ + \ + if (!da_monitor_enabled_##name()) \ + return 0; \ + \ + /* monitor is actually monitoring */ \ + if (unlikely(!da_monitoring_##name(da_mon))) \ + return 0; \ + \ + return 1; \ +} + +/* + * Event handler for implicit monitors. Implicit monitor is the one which the + * handler does not need to specify which da_monitor to manipulate. Examples + * of implicit monitor are the per_cpu or the global ones. + */ +#define DECLARE_DA_MON_MODEL_HANDLER_IMPLICIT(name, type) \ + \ +static inline bool \ +da_event_##name(struct da_monitor *da_mon, enum events_##name event) \ +{ \ + type curr_state = da_monitor_curr_state_##name(da_mon); \ + type next_state = model_get_next_state_##name(curr_state, event); \ + \ + if (next_state != INVALID_STATE) { \ + da_monitor_set_state_##name(da_mon, next_state); \ + \ + trace_event_##name(model_get_state_name_##name(curr_state), \ + model_get_event_name_##name(event), \ + model_get_state_name_##name(next_state), \ + model_is_final_state_##name(next_state)); \ + \ + return true; \ + } \ + \ + if (rv_reacting_on_##name()) \ + cond_react_##name(format_react_msg_##name(curr_state, event)); \ + \ + trace_error_##name(model_get_state_name_##name(curr_state), \ + model_get_event_name_##name(event)); \ + \ + return false; \ +} \ + +/* + * Event handler for per_task monitors. + */ +#define DECLARE_DA_MON_MODEL_HANDLER_PER_TASK(name, type) \ + \ +static inline bool da_event_##name(struct da_monitor *da_mon, struct task_struct *tsk, \ + enum events_##name event) \ +{ \ + type curr_state = da_monitor_curr_state_##name(da_mon); \ + type next_state = model_get_next_state_##name(curr_state, event); \ + \ + if (next_state != INVALID_STATE) { \ + da_monitor_set_state_##name(da_mon, next_state); \ + \ + trace_event_##name(tsk->pid, \ + model_get_state_name_##name(curr_state), \ + model_get_event_name_##name(event), \ + model_get_state_name_##name(next_state), \ + model_is_final_state_##name(next_state)); \ + \ + return true; \ + } \ + \ + if (rv_reacting_on_##name()) \ + cond_react_##name(format_react_msg_##name(curr_state, event)); \ + \ + trace_error_##name(tsk->pid, \ + model_get_state_name_##name(curr_state), \ + model_get_event_name_##name(event)); \ + \ + return false; \ +} + +/* + * Functions to define, init and get a global monitor. + */ +#define DECLARE_DA_MON_INIT_GLOBAL(name, type) \ + \ +/* \ + * global monitor (a single variable) \ + */ \ +static struct da_monitor da_mon_##name; \ + \ +/* \ + * da_get_monitor_##name - return the global monitor address \ + */ \ +static struct da_monitor *da_get_monitor_##name(void) \ +{ \ + return &da_mon_##name; \ +} \ + \ +/* \ + * da_monitor_reset_all_##name - reset the single monitor \ + */ \ +static void da_monitor_reset_all_##name(void) \ +{ \ + da_monitor_reset_##name(da_get_monitor_##name()); \ +} \ + \ +/* \ + * da_monitor_init_##name - initialize a monitor \ + */ \ +static inline int da_monitor_init_##name(void) \ +{ \ + da_monitor_reset_all_##name(); \ + return 0; \ +} \ + \ +/* \ + * da_monitor_destroy_##name - destroy the monitor \ + */ \ +static inline void da_monitor_destroy_##name(void) \ +{ \ + return; \ +} + +/* + * Functions to define, init and get a per-cpu monitor. + */ +#define DECLARE_DA_MON_INIT_PER_CPU(name, type) \ + \ +/* \ + * per-cpu monitor variables \ + */ \ +DEFINE_PER_CPU(struct da_monitor, da_mon_##name); \ + \ +/* \ + * da_get_monitor_##name - return current CPU monitor address \ + */ \ +static struct da_monitor *da_get_monitor_##name(void) \ +{ \ + return this_cpu_ptr(&da_mon_##name); \ +} \ + \ +/* \ + * da_monitor_reset_all_##name - reset all CPUs' monitor \ + */ \ +static void da_monitor_reset_all_##name(void) \ +{ \ + struct da_monitor *da_mon; \ + int cpu; \ + for_each_cpu(cpu, cpu_online_mask) { \ + da_mon = per_cpu_ptr(&da_mon_##name, cpu); \ + da_monitor_reset_##name(da_mon); \ + } \ +} \ + \ +/* \ + * da_monitor_init_##name - initialize all CPUs' monitor \ + */ \ +static inline int da_monitor_init_##name(void) \ +{ \ + da_monitor_reset_all_##name(); \ + return 0; \ +} \ + \ +/* \ + * da_monitor_destroy_##name - destroy the monitor \ + */ \ +static inline void da_monitor_destroy_##name(void) \ +{ \ + return; \ +} + +/* + * Functions to define, init and get a per-task monitor. + */ +#define DECLARE_DA_MON_INIT_PER_TASK(name, type) \ + \ +/* \ + * The per-task monitor is stored a vector in the task struct. This variable \ + * stores the position on the vector reserved for this monitor. \ + */ \ +static int task_mon_slot_##name = RV_PER_TASK_MONITOR_INIT; \ + \ +/* \ + * da_get_monitor_##name - return the monitor in the allocated slot for tsk \ + */ \ +static inline struct da_monitor *da_get_monitor_##name(struct task_struct *tsk) \ +{ \ + return &tsk->rv[task_mon_slot_##name].da_mon; \ +} \ + \ +static void da_monitor_reset_all_##name(void) \ +{ \ + struct task_struct *g, *p; \ + \ + read_lock(&tasklist_lock); \ + for_each_process_thread(g, p) \ + da_monitor_reset_##name(da_get_monitor_##name(p)); \ + read_unlock(&tasklist_lock); \ +} \ + \ +/* \ + * da_monitor_init_##name - initialize the per-task monitor \ + * \ + * Try to allocate a slot in the task's vector of monitors. If there \ + * is an available slot, use it and reset all task's monitor. \ + */ \ +static int da_monitor_init_##name(void) \ +{ \ + int slot; \ + \ + slot = rv_get_task_monitor_slot(); \ + if (slot < 0 || slot >= RV_PER_TASK_MONITOR_INIT) \ + return slot; \ + \ + task_mon_slot_##name = slot; \ + \ + da_monitor_reset_all_##name(); \ + return 0; \ +} \ + \ +/* \ + * da_monitor_destroy_##name - return the allocated slot \ + */ \ +static inline void da_monitor_destroy_##name(void) \ +{ \ + if (task_mon_slot_##name == RV_PER_TASK_MONITOR_INIT) { \ + WARN_ONCE(1, "Disabling a disabled monitor: " #name); \ + return; \ + } \ + rv_put_task_monitor_slot(task_mon_slot_##name); \ + task_mon_slot_##name = RV_PER_TASK_MONITOR_INIT; \ + return; \ +} + +/* + * Handle event for implicit monitor: da_get_monitor_##name() will figure out + * the monitor. + */ +#define DECLARE_DA_MON_MONITOR_HANDLER_IMPLICIT(name, type) \ + \ +static inline void __da_handle_event_##name(struct da_monitor *da_mon, \ + enum events_##name event) \ +{ \ + bool retval; \ + \ + retval = da_event_##name(da_mon, event); \ + if (!retval) \ + da_monitor_reset_##name(da_mon); \ +} \ + \ +/* \ + * da_handle_event_##name - handle an event \ + */ \ +static inline void da_handle_event_##name(enum events_##name event) \ +{ \ + struct da_monitor *da_mon = da_get_monitor_##name(); \ + bool retval; \ + \ + retval = da_monitor_handling_event_##name(da_mon); \ + if (!retval) \ + return; \ + \ + __da_handle_event_##name(da_mon, event); \ +} \ + \ +/* \ + * da_handle_start_event_##name - start monitoring or handle event \ + * \ + * This function is used to notify the monitor that the system is returning \ + * to the initial state, so the monitor can start monitoring in the next event. \ + * Thus: \ + * \ + * If the monitor already started, handle the event. \ + * If the monitor did not start yet, start the monitor but skip the event. \ + */ \ +static inline bool da_handle_start_event_##name(enum events_##name event) \ +{ \ + struct da_monitor *da_mon; \ + \ + if (!da_monitor_enabled_##name()) \ + return 0; \ + \ + da_mon = da_get_monitor_##name(); \ + \ + if (unlikely(!da_monitoring_##name(da_mon))) { \ + da_monitor_start_##name(da_mon); \ + return 0; \ + } \ + \ + __da_handle_event_##name(da_mon, event); \ + \ + return 1; \ +} \ + \ +/* \ + * da_handle_start_run_event_##name - start monitoring and handle event \ + * \ + * This function is used to notify the monitor that the system is in the \ + * initial state, so the monitor can start monitoring and handling event. \ + */ \ +static inline bool da_handle_start_run_event_##name(enum events_##name event) \ +{ \ + struct da_monitor *da_mon; \ + \ + if (!da_monitor_enabled_##name()) \ + return 0; \ + \ + da_mon = da_get_monitor_##name(); \ + \ + if (unlikely(!da_monitoring_##name(da_mon))) \ + da_monitor_start_##name(da_mon); \ + \ + __da_handle_event_##name(da_mon, event); \ + \ + return 1; \ +} + +/* + * Handle event for per task. + */ +#define DECLARE_DA_MON_MONITOR_HANDLER_PER_TASK(name, type) \ + \ +static inline void \ +__da_handle_event_##name(struct da_monitor *da_mon, struct task_struct *tsk, \ + enum events_##name event) \ +{ \ + bool retval; \ + \ + retval = da_event_##name(da_mon, tsk, event); \ + if (!retval) \ + da_monitor_reset_##name(da_mon); \ +} \ + \ +/* \ + * da_handle_event_##name - handle an event \ + */ \ +static inline void \ +da_handle_event_##name(struct task_struct *tsk, enum events_##name event) \ +{ \ + struct da_monitor *da_mon = da_get_monitor_##name(tsk); \ + bool retval; \ + \ + retval = da_monitor_handling_event_##name(da_mon); \ + if (!retval) \ + return; \ + \ + __da_handle_event_##name(da_mon, tsk, event); \ +} \ + \ +/* \ + * da_handle_start_event_##name - start monitoring or handle event \ + * \ + * This function is used to notify the monitor that the system is returning \ + * to the initial state, so the monitor can start monitoring in the next event. \ + * Thus: \ + * \ + * If the monitor already started, handle the event. \ + * If the monitor did not start yet, start the monitor but skip the event. \ + */ \ +static inline bool \ +da_handle_start_event_##name(struct task_struct *tsk, enum events_##name event) \ +{ \ + struct da_monitor *da_mon; \ + \ + if (!da_monitor_enabled_##name()) \ + return 0; \ + \ + da_mon = da_get_monitor_##name(tsk); \ + \ + if (unlikely(!da_monitoring_##name(da_mon))) { \ + da_monitor_start_##name(da_mon); \ + return 0; \ + } \ + \ + __da_handle_event_##name(da_mon, tsk, event); \ + \ + return 1; \ +} + +/* + * Entry point for the global monitor. + */ +#define DECLARE_DA_MON_GLOBAL(name, type) \ + \ +DECLARE_AUTOMATA_HELPERS(name, type) \ +DECLARE_DA_MON_GENERIC_HELPERS(name, type) \ +DECLARE_DA_MON_MODEL_HANDLER_IMPLICIT(name, type) \ +DECLARE_DA_MON_INIT_GLOBAL(name, type) \ +DECLARE_DA_MON_MONITOR_HANDLER_IMPLICIT(name, type) + +/* + * Entry point for the per-cpu monitor. + */ +#define DECLARE_DA_MON_PER_CPU(name, type) \ + \ +DECLARE_AUTOMATA_HELPERS(name, type) \ +DECLARE_DA_MON_GENERIC_HELPERS(name, type) \ +DECLARE_DA_MON_MODEL_HANDLER_IMPLICIT(name, type) \ +DECLARE_DA_MON_INIT_PER_CPU(name, type) \ +DECLARE_DA_MON_MONITOR_HANDLER_IMPLICIT(name, type) + +/* + * Entry point for the per-task monitor. + */ +#define DECLARE_DA_MON_PER_TASK(name, type) \ + \ +DECLARE_AUTOMATA_HELPERS(name, type) \ +DECLARE_DA_MON_GENERIC_HELPERS(name, type) \ +DECLARE_DA_MON_MODEL_HANDLER_PER_TASK(name, type) \ +DECLARE_DA_MON_INIT_PER_TASK(name, type) \ +DECLARE_DA_MON_MONITOR_HANDLER_PER_TASK(name, type) diff --git a/include/trace/events/rv.h b/include/trace/events/rv.h new file mode 100644 index 000000000000..20a2e09c6416 --- /dev/null +++ b/include/trace/events/rv.h @@ -0,0 +1,120 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM rv + +#if !defined(_TRACE_RV_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_RV_H + +#include +#include + +#ifdef CONFIG_DA_MON_EVENTS_IMPLICIT +DECLARE_EVENT_CLASS(event_da_monitor, + + TP_PROTO(char *state, char *event, char *next_state, bool final_state), + + TP_ARGS(state, event, next_state, final_state), + + TP_STRUCT__entry( + __array( char, state, MAX_DA_NAME_LEN ) + __array( char, event, MAX_DA_NAME_LEN ) + __array( char, next_state, MAX_DA_NAME_LEN ) + __field( bool, final_state ) + ), + + TP_fast_assign( + memcpy(__entry->state, state, MAX_DA_NAME_LEN); + memcpy(__entry->event, event, MAX_DA_NAME_LEN); + memcpy(__entry->next_state, next_state, MAX_DA_NAME_LEN); + __entry->final_state = final_state; + ), + + TP_printk("%s x %s -> %s %s", + __entry->state, + __entry->event, + __entry->next_state, + __entry->final_state ? "(final)" : "") +); + +DECLARE_EVENT_CLASS(error_da_monitor, + + TP_PROTO(char *state, char *event), + + TP_ARGS(state, event), + + TP_STRUCT__entry( + __array( char, state, MAX_DA_NAME_LEN ) + __array( char, event, MAX_DA_NAME_LEN ) + ), + + TP_fast_assign( + memcpy(__entry->state, state, MAX_DA_NAME_LEN); + memcpy(__entry->event, event, MAX_DA_NAME_LEN); + ), + + TP_printk("event %s not expected in the state %s", + __entry->event, + __entry->state) +); +#endif /* CONFIG_DA_MON_EVENTS_IMPLICIT */ + +#ifdef CONFIG_DA_MON_EVENTS_ID +DECLARE_EVENT_CLASS(event_da_monitor_id, + + TP_PROTO(int id, char *state, char *event, char *next_state, bool final_state), + + TP_ARGS(id, state, event, next_state, final_state), + + TP_STRUCT__entry( + __field( int, id ) + __array( char, state, MAX_DA_NAME_LEN ) + __array( char, event, MAX_DA_NAME_LEN ) + __array( char, next_state, MAX_DA_NAME_LEN ) + __field( bool, final_state ) + ), + + TP_fast_assign( + memcpy(__entry->state, state, MAX_DA_NAME_LEN); + memcpy(__entry->event, event, MAX_DA_NAME_LEN); + memcpy(__entry->next_state, next_state, MAX_DA_NAME_LEN); + __entry->id = id; + __entry->final_state = final_state; + ), + + TP_printk("%d: %s x %s -> %s %s", + __entry->id, + __entry->state, + __entry->event, + __entry->next_state, + __entry->final_state ? "(final)" : "") +); + +DECLARE_EVENT_CLASS(error_da_monitor_id, + + TP_PROTO(int id, char *state, char *event), + + TP_ARGS(id, state, event), + + TP_STRUCT__entry( + __field( int, id ) + __array( char, state, MAX_DA_NAME_LEN ) + __array( char, event, MAX_DA_NAME_LEN ) + ), + + TP_fast_assign( + memcpy(__entry->state, state, MAX_DA_NAME_LEN); + memcpy(__entry->event, event, MAX_DA_NAME_LEN); + __entry->id = id; + ), + + TP_printk("%d: event %s not expected in the state %s", + __entry->id, + __entry->event, + __entry->state) +); +#endif /* CONFIG_DA_MON_EVENTS_ID */ +#endif /* _TRACE_RV_H */ + +/* This part ust be outside protection */ +#undef TRACE_INCLUDE_PATH +#include diff --git a/kernel/fork.c b/kernel/fork.c index 9d44f2d46c69..6f1f82ccd5f2 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1964,6 +1964,18 @@ static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk) mutex_unlock(&oom_adj_mutex); } +#ifdef CONFIG_RV +static void rv_task_fork(struct task_struct *p) +{ + int i; + + for (i = 0; i < RV_PER_TASK_MONITORS; i++) + p->rv[i].da_mon.monitoring = false; +} +#else +#define rv_task_fork(p) do {} while (0) +#endif + /* * This creates a new process as a copy of the old one, * but does not actually start it yet. @@ -2399,6 +2411,8 @@ static __latent_entropy struct task_struct *copy_process( */ copy_seccomp(p); + rv_task_fork(p); + rseq_fork(p, clone_flags); /* Don't start children in a dying pid namespace */ diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig index 3eb5d48ab4f6..8714800e22ad 100644 --- a/kernel/trace/rv/Kconfig +++ b/kernel/trace/rv/Kconfig @@ -1,5 +1,16 @@ # SPDX-License-Identifier: GPL-2.0-only # +config DA_MON_EVENTS + bool + +config DA_MON_EVENTS_IMPLICIT + select DA_MON_EVENTS + bool + +config DA_MON_EVENTS_ID + select DA_MON_EVENTS + bool + menuconfig RV bool "Runtime Verification" depends on TRACING diff --git a/kernel/trace/rv/rv.c b/kernel/trace/rv/rv.c index 45cf64eb2600..df6678c86334 100644 --- a/kernel/trace/rv/rv.c +++ b/kernel/trace/rv/rv.c @@ -140,6 +140,11 @@ #include #include +#ifdef CONFIG_DA_MON_EVENTS +#define CREATE_TRACE_POINTS +#include +#endif + #include "rv.h" DEFINE_MUTEX(rv_interface_lock); From patchwork Fri Jul 29 09:38:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932247 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 8471AC25B06 for ; Fri, 29 Jul 2022 09:39:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235699AbiG2Jjh (ORCPT ); Fri, 29 Jul 2022 05:39:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37586 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235707AbiG2Jjg (ORCPT ); Fri, 29 Jul 2022 05:39:36 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E3EDF85FBD; Fri, 29 Jul 2022 02:39:34 -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 ams.source.kernel.org (Postfix) with ESMTPS id A640AB8232F; Fri, 29 Jul 2022 09:39:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DEB27C433C1; Fri, 29 Jul 2022 09:39:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087572; bh=tFQeIFcFJY3lIF68AI4Lr4svxai5erbmpSh5Zi8+S+4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sSOLYhnFVecmuCQwFU/dVUvaabso05mvjr177NvBHDOymmcR6SQNGystFd2P+S7Ob K5aVo8+Fu/Qwlw0ZccGSsinDfIuYNQSDFAz6uxDoOcjCmHY3j9RUxjZDK8OuuiN/b3 wAbG5AggCTJGT9Ti3fTRGdCk3WUORhvjwIrOqWIQpyuyTdx/6hPmQtimd/jUQ2SfLD KOrHMDpPt31t3rnomvqGICFEOBWUn1Koqu/sqCEAi5Mz1CbO4qqLF3Jl6ADw4zj7AY NX4bYi1q2gE0oP1VmaYR1pnv2SqwNE2Z1KoK/rHaHjyKMCDJRRHfKCker0sANYtle1 +EayHD7kzGwTg== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 05/16] rv/include: Add instrumentation helper functions Date: Fri, 29 Jul 2022 11:38:44 +0200 Message-Id: <3b36c9435f9d9299beb84e5c7c46920e205bedec.1659052063.git.bristot@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Instrumentation helper functions to facilitate the instrumentation of auto-generated RV monitors create by dot2k. Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- include/rv/instrumentation.h | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) create mode 100644 include/rv/instrumentation.h diff --git a/include/rv/instrumentation.h b/include/rv/instrumentation.h new file mode 100644 index 000000000000..d4e7a02ede1a --- /dev/null +++ b/include/rv/instrumentation.h @@ -0,0 +1,29 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira + * + * Helper functions to facilitate the instrumentation of auto-generated + * RV monitors create by dot2k. + * + * The dot2k tool is available at tools/verification/dot2/ + */ + +#include + +/* + * rv_attach_trace_probe - check and attach a handler function to a tracepoint + */ +#define rv_attach_trace_probe(monitor, tp, rv_handler) \ + do { \ + check_trace_callback_type_##tp(rv_handler); \ + WARN_ONCE(register_trace_##tp(rv_handler, NULL), \ + "fail attaching " #monitor " " #tp "handler"); \ + } while (0) + +/* + * rv_detach_trace_probe - detach a handler function to a tracepoint + */ +#define rv_detach_trace_probe(monitor, tp, rv_handler) \ + do { \ + unregister_trace_##tp(rv_handler, NULL); \ + } while (0) From patchwork Fri Jul 29 09:38:45 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932248 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 BE749C00144 for ; Fri, 29 Jul 2022 09:40:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235790AbiG2JkA (ORCPT ); Fri, 29 Jul 2022 05:40:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38222 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235709AbiG2Jj5 (ORCPT ); Fri, 29 Jul 2022 05:39:57 -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 2C2BF85FA2; Fri, 29 Jul 2022 02:39:39 -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 0A07661D96; Fri, 29 Jul 2022 09:39:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DF2CDC43140; Fri, 29 Jul 2022 09:39:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087577; bh=rNw6bNVBJW91nAxwr+pPQzjf754so4YwlHlgpyJgLqo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TOoEPmS8Nbx0m6NMycO9BPa7dNcOHoXLml7DqxjKldOCx2iu+h6dx7VWfxMwi9Dmb K5YVzl4VBFwThQ5yItWU707azwFSON2Cn/uJCnHkgVBifIyj3sKi2hN3Y220vQcSy9 v9aeMUO53UrWrve503Ddjg3613ufdn8DIdo/IQFnj+eRh6StVYWtrERQEuiHceCyF3 Yi61HuMcSO6GwXKbIz1wrt8oG5wDq9wuXknNGC2UMrnF36LOVMOueD4Ru1DPwFfHAY ObK7eazU33PnvMr4EL27OQer+SA5GHy0RDke5hjaHZBZ7weQXNvt701GreWGDNCw8T Z5GaAH0376qwA== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 06/16] Documentation/rv: Add a basic documentation Date: Fri, 29 Jul 2022 11:38:45 +0200 Message-Id: <4be7d1a88ab1e2eb0767521e1ab52a149a154bc4.1659052063.git.bristot@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Add the runtime-verification.rst document, explaining the basics of RV and how to use the interface. Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- Documentation/trace/index.rst | 1 + Documentation/trace/rv/index.rst | 9 + .../trace/rv/runtime-verification.rst | 231 ++++++++++++++++++ kernel/trace/rv/Kconfig | 3 + kernel/trace/rv/rv.c | 3 + 5 files changed, 247 insertions(+) create mode 100644 Documentation/trace/rv/index.rst create mode 100644 Documentation/trace/rv/runtime-verification.rst diff --git a/Documentation/trace/index.rst b/Documentation/trace/index.rst index f9b7bcb5a630..2d73e8697523 100644 --- a/Documentation/trace/index.rst +++ b/Documentation/trace/index.rst @@ -32,3 +32,4 @@ Linux Tracing Technologies sys-t coresight/index user_events + rv/index diff --git a/Documentation/trace/rv/index.rst b/Documentation/trace/rv/index.rst new file mode 100644 index 000000000000..b54e49b1d0de --- /dev/null +++ b/Documentation/trace/rv/index.rst @@ -0,0 +1,9 @@ +==================== +Runtime Verification +==================== + +.. toctree:: + :maxdepth: 2 + :glob: + + runtime-verification.rst diff --git a/Documentation/trace/rv/runtime-verification.rst b/Documentation/trace/rv/runtime-verification.rst new file mode 100644 index 000000000000..c46b6149470e --- /dev/null +++ b/Documentation/trace/rv/runtime-verification.rst @@ -0,0 +1,231 @@ +==================== +Runtime Verification +==================== + +Runtime Verification (RV) is a lightweight (yet rigorous) method that +complements classical exhaustive verification techniques (such as *model +checking* and *theorem proving*) with a more practical approach for complex +systems. + +Instead of relying on a fine-grained model of a system (e.g., a +re-implementation a instruction level), RV works by analyzing the trace of the +system's actual execution, comparing it against a formal specification of +the system behavior. + +The main advantage is that RV can give precise information on the runtime +behavior of the monitored system, without the pitfalls of developing models +that require a re-implementation of the entire system in a modeling language. +Moreover, given an efficient monitoring method, it is possible execute an +*online* verification of a system, enabling the *reaction* for unexpected +events, avoiding, for example, the propagation of a failure on safety-critical +systems. + +Runtime Monitors and Reactors +============================= + +A monitor is the central part of the runtime verification of a system. The +monitor stands in between the formal specification of the desired (or +undesired) behavior, and the trace of the actual system. + +In Linux terms, the runtime verification monitors are encapsulated inside the +*RV monitor* abstraction. A *RV monitor* includes a reference model of the +system, a set of instances of the monitor (per-cpu monitor, per-task monitor, +and so on), and the helper functions that glue the monitor to the system via +trace, as depicted bellow:: + + Linux +---- RV Monitor ----------------------------------+ Formal + Realm | | Realm + +-------------------+ +----------------+ +-----------------+ + | Linux kernel | | Monitor | | Reference | + | Tracing | -> | Instance(s) | <- | Model | + | (instrumentation) | | (verification) | | (specification) | + +-------------------+ +----------------+ +-----------------+ + | | | + | V | + | +----------+ | + | | Reaction | | + | +--+--+--+-+ | + | | | | | + | | | +-> trace output ? | + +------------------------|--|----------------------+ + | +----> panic ? + +-------> + +In addition to the verification and monitoring of the system, a monitor can +react to an unexpected event. The forms of reaction can vary from logging the +event occurrence to the enforcement of the correct behavior to the extreme +action of taking a system down to avoid the propagation of a failure. + +In Linux terms, a *reactor* is an reaction method available for *RV monitors*. +By default, all monitors should provide a trace output of their actions, +which is already a reaction. In addition, other reactions will be available +so the user can enable them as needed. + +For further information about the principles of runtime verification and +RV applied to Linux: + + Bartocci, Ezio, et al. *Introduction to runtime verification.* In: Lectures on + Runtime Verification. Springer, Cham, 2018. p. 1-33. + + Falcone, Ylies, et al. *A taxonomy for classifying runtime verification tools.* + In: International Conference on Runtime Verification. Springer, Cham, 2018. p. + 241-262. + + De Oliveira, Daniel Bristot. *Automata-based formal analysis and + verification of the real-time Linux kernel.* Ph.D. Thesis, 2020. + +Online RV monitors +================== + +Monitors can be classified as *offline* and *online* monitors. *Offline* +monitor process the traces generated by a system after the events, generally by +reading the trace execution from a permanent storage system. *Online* monitors +process the trace during the execution of the system. Online monitors are said +to be *synchronous* if the processing of an event is attached to the system +execution, blocking the system during the event monitoring. On the other hand, +an *asynchronous* monitor has its execution detached from the system. Each type +of monitor has a set of advantages. For example, *offline* monitors can be +executed on different machines but require operations to save the log to a +file. In contrast, *synchronous online* method can react at the exact moment +a violation occurs. + +Another important aspect regarding monitors is the overhead associated with the +event analysis. If the system generates events at a frequency higher than the +monitor's ability to process them in the same system, only the *offline* +methods are viable. On the other hand, if the tracing of the events incurs +on higher overhead than the simple handling of an event by a monitor, then a +*synchronous online* monitors will incur on lower overhead. + +Indeed, the research presented in: + + De Oliveira, Daniel Bristot; Cucinotta, Tommaso; De Oliveira, Romulo Silva. + *Efficient formal verification for the Linux kernel.* In: International + Conference on Software Engineering and Formal Methods. Springer, Cham, 2019. + p. 315-332. + +Shows that for Deterministic Automata models, the synchronous processing of +events in-kernel causes lower overhead than saving the same events to the trace +buffer, not even considering collecting the trace for user-space analysis. +This motivated the development of an in-kernel interface for online monitors. + +For further information about modeling of Linux kernel behavior using automata, +see: + + De Oliveira, Daniel B.; De Oliveira, Romulo S.; Cucinotta, Tommaso. *A thread + synchronization model for the PREEMPT_RT Linux kernel.* Journal of Systems + Architecture, 2020, 107: 101729. + +The user interface +================== + +The user interface resembles the tracing interface (on purpose). It is +currently at "/sys/kernel/tracing/rv/". + +The following files/folders are currently available: + +**available_monitors** + +- Reading list the available monitors, one per line + +For example:: + + # cat available_monitors + wip + wwnr + +**available_reactors** + +- Reading shows the available reactors, one per line. + +For example:: + + # cat available_reactors + nop + panic + printk + +**enabled_monitors**: + +- Reading lists the enabled monitors, one per line +- Writing to it enables a given monitor +- Writing a monitor name with a '!' prefix disables it +- Truncating the file disables all enabled monitors + +For example:: + + # cat enabled_monitors + # echo wip > enabled_monitors + # echo wwnr >> enabled_monitors + # cat enabled_monitors + wip + wwnr + # echo '!wip' >> enabled_monitors + # cat enabled_monitors + wwnr + # echo > enabled_monitors + # cat enabled_monitors + # + +Note that it is possible to enable more than one monitor concurrently. + +**monitoring_on** + +This is an on/off general switcher for monitoring. It resembles the +"tracing_on" switcher in the trace interface. + +- Writing "0" stops the monitoring +- Writing "1" continues the monitoring +- Reading returns the current status of the monitoring + +Note that it does not disable enabled monitors but stop the per-entity +monitors monitoring the events received from the system. + +**reacting_on** + +- Writing "0" prevents reactions for happening +- Writing "1" enable reactions +- Reading returns the current status of the reaction + +**monitors/** + +Each monitor will have its own directory inside "monitors/". There the +monitor-specific files will be presented. The "monitors/" directory resembles +the "events" directory on tracefs. + +For example:: + + # cd monitors/wip/ + # ls + desc enable + # cat desc + wakeup in preemptive per-cpu testing monitor. + # cat enable + 0 + +**monitors/MONITOR/desc** + +- Reading shows a description of the monitor *MONITOR* + +**monitors/MONITOR/enable** + +- Writing "0" disables the *MONITOR* +- Writing "1" enables the *MONITOR* +- Reading return the current status of the *MONITOR* + +**monitors/MONITOR/reactors** + +- List available reactors, with the select reaction for the given *MONITOR* + inside "[]". The default one is the nop (no operation) reactor. +- Writing the name of a reactor enables it to the given MONITOR. + +For example:: + + # cat monitors/wip/reactors + [nop] + panic + printk + # echo panic > monitors/wip/reactors + # cat monitors/wip/reactors + nop + [panic] + printk diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig index 8714800e22ad..0d9552b406c6 100644 --- a/kernel/trace/rv/Kconfig +++ b/kernel/trace/rv/Kconfig @@ -22,6 +22,9 @@ menuconfig RV actual execution, comparing it against a formal specification of the system behavior. + For further information, see: + Documentation/trace/rv/runtime-verification.rst + config RV_REACTORS bool "Runtime verification reactors" default y diff --git a/kernel/trace/rv/rv.c b/kernel/trace/rv/rv.c index df6678c86334..6c97cc2d754a 100644 --- a/kernel/trace/rv/rv.c +++ b/kernel/trace/rv/rv.c @@ -133,6 +133,9 @@ * auto-generated wakeup in preemptive monitor. * # cat enable * 0 + * + * For further information, see: + * Documentation/trace/rv/runtime-verification.rst */ #include From patchwork Fri Jul 29 09:38:46 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932249 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 B8110C19F2B for ; Fri, 29 Jul 2022 09:40:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235858AbiG2JkP (ORCPT ); Fri, 29 Jul 2022 05:40:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38434 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235802AbiG2JkA (ORCPT ); Fri, 29 Jul 2022 05:40:00 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47E9B86880; Fri, 29 Jul 2022 02:39:43 -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 14E4A61DAB; Fri, 29 Jul 2022 09:39:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E13D3C433D6; Fri, 29 Jul 2022 09:39:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087582; bh=aTFFUhV/ovGh1pL4592w1TWqGPvo+d89bBF6ifbVuJ4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RyWHCGt1of+ey0i/4GyM5E/kDuw4E/C1EbjfHhWkt2h31uZS11fwJhC2lfNG2MkHj s5Eqg8AhL40moHAr6/NkW5RbsNX9M4fcw6IIMaMLl2ofXHtNgEwZnZt1lvJQtTFIZ6 bXFDjaPFGuub3Km9IBaS16aU+Ha2wCRDjyDREM7Iy1hudVIrYNBjYs/X5yR1QLaDX9 MA9uKYSbQRcWT2zh99B6UDeSmDib3jhIcolAc5LoudiM8NeJwNTxJ41gxsvvhGlrqj qgvw7g06IaYTZbcd8OsO54QDRqRlSLYjiFyoFx25j7gmHKTTC1poe+X9cR/4XasVBz C1YWf86ykPrAg== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 07/16] tools/rv: Add dot2c Date: Fri, 29 Jul 2022 11:38:46 +0200 Message-Id: X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org dot2c is a tool that transforms an automata in the graphiviz .dot file into an C representation of the automata. usage: dot2c [-h] dot_file dot2c: converts a .dot file into a C structure positional arguments: dot_file The dot file to be converted optional arguments: -h, --help show this help message and exit Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- tools/verification/dot2/Makefile | 21 +++ tools/verification/dot2/automata.py | 171 +++++++++++++++++++ tools/verification/dot2/dot2c | 23 +++ tools/verification/dot2/dot2c.py | 251 ++++++++++++++++++++++++++++ 4 files changed, 466 insertions(+) create mode 100644 tools/verification/dot2/Makefile create mode 100644 tools/verification/dot2/automata.py create mode 100644 tools/verification/dot2/dot2c create mode 100644 tools/verification/dot2/dot2c.py diff --git a/tools/verification/dot2/Makefile b/tools/verification/dot2/Makefile new file mode 100644 index 000000000000..235d182f6b2c --- /dev/null +++ b/tools/verification/dot2/Makefile @@ -0,0 +1,21 @@ +INSTALL=install + +prefix ?= /usr +bindir ?= $(prefix)/bin +mandir ?= $(prefix)/share/man +miscdir ?= $(prefix)/share/dot2 +srcdir ?= $(prefix)/src + +PYLIB ?= $(shell python3 -c 'import sysconfig; print (sysconfig.get_path("purelib"))') + +.PHONY: all +all: + +.PHONY: clean +clean: + +.PHONY: install +install: + $(INSTALL) automata.py -D -m 644 $(DESTDIR)$(PYLIB)/dot2/automata.py + $(INSTALL) dot2c.py -D -m 644 $(DESTDIR)$(PYLIB)/dot2/dot2c.py + $(INSTALL) dot2c -D -m 755 $(DESTDIR)$(bindir)/ diff --git a/tools/verification/dot2/automata.py b/tools/verification/dot2/automata.py new file mode 100644 index 000000000000..f22e1dff19ce --- /dev/null +++ b/tools/verification/dot2/automata.py @@ -0,0 +1,171 @@ +#!/usr/bin/env python3 +# SPDX-License-Identifier: GPL-2.0-only +# +# Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira +# +# Automata object: parse an automata in dot file digraph format into a python object + +import ntpath + +class Automata: + """Automata class: Reads a dot file and part it as an automata. + + Attributes: + dot_file: A dot file with an state_automaton definition. + """ + + invalid_state_str = "INVALID_STATE" + + def __init__(self, file_path): + self.__dot_path = file_path + self.name = self.__get_model_name() + self.__dot_lines = self.__open_dot() + self.states, self.initial_state, self.final_states = self.__get_state_variables() + self.events = self.__get_event_variables() + self.function = self.__create_matrix() + + def __get_model_name(self): + basename = ntpath.basename(self.__dot_path) + if basename.endswith(".dot") == False: + print("not a dot file") + raise Exception("not a dot file: %s" % self.__dot_path) + + model_name = basename[0:-4] + if model_name.__len__() == 0: + raise Exception("not a dot file: %s" % self.__dot_path) + + return model_name + + def __open_dot(self): + cursor = 0 + dot_lines = [] + try: + dot_file = open(self.__dot_path) + except: + raise Exception("Cannot open the file: %s" % self.__dot_path) + + dot_lines = dot_file.read().splitlines() + dot_file.close() + + # checking the first line: + line = dot_lines[cursor].split() + + if (line[0] != "digraph") and (line[1] != "state_automaton"): + raise Exception("Not a valid .dot format: %s" % self.__dot_path) + else: + cursor += 1 + return dot_lines + + def __get_cursor_begin_states(self): + cursor = 0 + while self.__dot_lines[cursor].split()[0] != "{node": + cursor += 1 + return cursor + + def __get_cursor_begin_events(self): + cursor = 0 + while self.__dot_lines[cursor].split()[0] != "{node": + cursor += 1 + while self.__dot_lines[cursor].split()[0] == "{node": + cursor += 1 + # skip initial state transition + cursor += 1 + return cursor + + def __get_state_variables(self): + # wait for node declaration + states = [] + final_states = [] + + has_final_states = False + cursor = self.__get_cursor_begin_states() + + # process nodes + while self.__dot_lines[cursor].split()[0] == "{node": + line = self.__dot_lines[cursor].split() + raw_state = line[-1] + + # "enabled_fired"}; -> enabled_fired + state = raw_state.replace('"', '').replace('};', '').replace(',','_') + if state[0:7] == "__init_": + initial_state = state[7:] + else: + states.append(state) + if self.__dot_lines[cursor].__contains__("doublecircle") == True: + final_states.append(state) + has_final_states = True + + if self.__dot_lines[cursor].__contains__("ellipse") == True: + final_states.append(state) + has_final_states = True + + cursor += 1 + + states = sorted(set(states)) + states.remove(initial_state) + + # Insert the initial state at the bein og the states + states.insert(0, initial_state) + + if has_final_states == False: + final_states.append(initial_state) + + return states, initial_state, final_states + + def __get_event_variables(self): + # here we are at the begin of transitions, take a note, we will return later. + cursor = self.__get_cursor_begin_events() + + events = [] + while self.__dot_lines[cursor][1] == '"': + # transitions have the format: + # "all_fired" -> "both_fired" [ label = "disable_irq" ]; + # ------------ event is here ------------^^^^^ + if self.__dot_lines[cursor].split()[1] == "->": + line = self.__dot_lines[cursor].split() + event = line[-2].replace('"','') + + # when a transition has more than one lables, they are like this + # "local_irq_enable\nhw_local_irq_enable_n" + # so split them. + + event = event.replace("\\n", " ") + for i in event.split(): + events.append(i) + cursor += 1 + + return sorted(set(events)) + + def __create_matrix(self): + # transform the array into a dictionary + events = self.events + states = self.states + events_dict = {} + states_dict = {} + nr_event = 0 + for event in events: + events_dict[event] = nr_event + nr_event += 1 + + nr_state = 0 + for state in states: + states_dict[state] = nr_state + nr_state += 1 + + # declare the matrix.... + matrix = [[ self.invalid_state_str for x in range(nr_event)] for y in range(nr_state)] + + # and we are back! Let's fill the matrix + cursor = self.__get_cursor_begin_events() + + while self.__dot_lines[cursor][1] == '"': + if self.__dot_lines[cursor].split()[1] == "->": + line = self.__dot_lines[cursor].split() + origin_state = line[0].replace('"','').replace(',','_') + dest_state = line[2].replace('"','').replace(',','_') + possible_events = line[-2].replace('"','').replace("\\n", " ") + for event in possible_events.split(): + matrix[states_dict[origin_state]][events_dict[event]] = dest_state + cursor += 1 + + return matrix diff --git a/tools/verification/dot2/dot2c b/tools/verification/dot2/dot2c new file mode 100644 index 000000000000..8a8cd84bdfcf --- /dev/null +++ b/tools/verification/dot2/dot2c @@ -0,0 +1,23 @@ +#!/usr/bin/env python3 +# SPDX-License-Identifier: GPL-2.0-only +# +# Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira +# +# dot2c: parse an automata in dot file digraph format into a C +# +# This program was written in the development of this paper: +# de Oliveira, D. B. and Cucinotta, T. and de Oliveira, R. S. +# "Efficient Formal Verification for the Linux Kernel." International +# Conference on Software Engineering and Formal Methods. Springer, Cham, 2019. + +if __name__ == '__main__': + from dot2 import dot2c + import argparse + import sys + + parser = argparse.ArgumentParser(description='dot2c: converts a .dot file into a C structure') + parser.add_argument('dot_file', help='The dot file to be converted') + + args = parser.parse_args() + d = dot2c.Dot2c(args.dot_file) + d.print_model_classic() diff --git a/tools/verification/dot2/dot2c.py b/tools/verification/dot2/dot2c.py new file mode 100644 index 000000000000..bca902eec483 --- /dev/null +++ b/tools/verification/dot2/dot2c.py @@ -0,0 +1,251 @@ +#!/usr/bin/env python3 +# SPDX-License-Identifier: GPL-2.0-only +# +# Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira +# +# dot2c: parse an automata in dot file digraph format into a C +# +# This program was written in the development of this paper: +# de Oliveira, D. B. and Cucinotta, T. and de Oliveira, R. S. +# "Efficient Formal Verification for the Linux Kernel." International +# Conference on Software Engineering and Formal Methods. Springer, Cham, 2019. + +from dot2.automata import Automata + +class Dot2c(Automata): + enum_suffix = "" + enum_states_def = "states" + enum_events_def = "events" + struct_automaton_def = "automaton" + var_automaton_def = "aut" + + def __init__(self, file_path): + super().__init__(file_path) + self.line_length = 100 + + def __buff_to_string(self, buff): + string = "" + + for line in buff: + string = string + line + "\n" + + # cut off the last \n + return string[:-1] + + def __get_enum_states_content(self): + buff = [] + buff.append("\t%s%s = 0," % (self.initial_state, self.enum_suffix)) + for state in self.states: + if state != self.initial_state: + buff.append("\t%s%s," % (state, self.enum_suffix)) + buff.append("\tstate_max%s" % (self.enum_suffix)) + + return buff + + def get_enum_states_string(self): + buff = self.__get_enum_states_content() + return self.__buff_to_string(buff) + + def format_states_enum(self): + buff = [] + buff.append("enum %s {" % self.enum_states_def) + buff.append(self.get_enum_states_string()) + buff.append("};\n") + + return buff + + def __get_enum_events_content(self): + buff = [] + first = True + for event in self.events: + if first: + buff.append("\t%s%s = 0," % (event, self.enum_suffix)) + first = False + else: + buff.append("\t%s%s," % (event, self.enum_suffix)) + + buff.append("\tevent_max%s" % self.enum_suffix) + + return buff + + def get_enum_events_string(self): + buff = self.__get_enum_events_content() + return self.__buff_to_string(buff) + + def format_events_enum(self): + buff = [] + buff.append("enum %s {" % self.enum_events_def) + buff.append(self.get_enum_events_string()) + buff.append("};\n") + + return buff + + def get_minimun_type(self): + min_type = "unsigned char" + + if self.states.__len__() > 255: + min_type = "unsigned short" + + if self.states.__len__() > 65535: + min_type = "unsigned int" + + if self.states.__len__() > 1000000: + raise Exception("Too many states: %d" % self.states.__len__()) + + return min_type + + def format_automaton_definition(self): + min_type = self.get_minimun_type() + buff = [] + buff.append("struct %s {" % self.struct_automaton_def) + buff.append("\tchar *state_names[state_max%s];" % (self.enum_suffix)) + buff.append("\tchar *event_names[event_max%s];" % (self.enum_suffix)) + buff.append("\t%s function[state_max%s][event_max%s];" % (min_type, self.enum_suffix, self.enum_suffix)) + buff.append("\t%s initial_state;" % min_type) + buff.append("\tbool final_states[state_max%s];" % (self.enum_suffix)) + buff.append("};\n") + return buff + + def format_aut_init_header(self): + buff = [] + buff.append("struct %s %s = {" % (self.struct_automaton_def, self.var_automaton_def)) + return buff + + def __get_string_vector_per_line_content(self, buff): + first = True + string = "" + for entry in buff: + if first: + string = string + "\t\t\"" + entry + first = False; + else: + string = string + "\",\n\t\t\"" + entry + string = string + "\"" + + return string + + def get_aut_init_events_string(self): + return self.__get_string_vector_per_line_content(self.events) + + def get_aut_init_states_string(self): + return self.__get_string_vector_per_line_content(self.states) + + def format_aut_init_events_string(self): + buff = [] + buff.append("\t.event_names = {") + buff.append(self.get_aut_init_events_string()) + buff.append("\t},") + return buff + + def format_aut_init_states_string(self): + buff = [] + buff.append("\t.state_names = {") + buff.append(self.get_aut_init_states_string()) + buff.append("\t},") + + return buff + + def __get_max_strlen_of_states(self): + max_state_name = max(self.states, key = len).__len__() + return max(max_state_name, self.invalid_state_str.__len__()) + + def __get_state_string_length(self): + maxlen = self.__get_max_strlen_of_states() + self.enum_suffix.__len__() + return "%" + str(maxlen) + "s" + + def get_aut_init_function(self): + nr_states = self.states.__len__() + nr_events = self.events.__len__() + buff = [] + + strformat = self.__get_state_string_length() + + for x in range(nr_states): + line = "\t\t{ " + for y in range(nr_events): + next_state = self.function[x][y] + if next_state != self.invalid_state_str: + next_state = self.function[x][y] + self.enum_suffix + + if y != nr_events-1: + line = line + strformat % next_state + ", " + else: + line = line + strformat % next_state + " }," + buff.append(line) + + return self.__buff_to_string(buff) + + def format_aut_init_function(self): + buff = [] + buff.append("\t.function = {") + buff.append(self.get_aut_init_function()) + buff.append("\t},") + + return buff + + def get_aut_init_initial_state(self): + return self.initial_state + + def format_aut_init_initial_state(self): + buff = [] + initial_state = self.get_aut_init_initial_state() + buff.append("\t.initial_state = " + initial_state + self.enum_suffix + ",") + + return buff + + def get_aut_init_final_states(self): + line = "" + first = True + for state in self.states: + if first == False: + line = line + ', ' + else: + first = False + + if self.final_states.__contains__(state): + line = line + '1' + else: + line = line + '0' + return line + + def format_aut_init_final_states(self): + buff = [] + buff.append("\t.final_states = { %s }," % self.get_aut_init_final_states()) + + return buff + + def __get_automaton_initialization_footer_string(self): + footer = "};\n" + return footer + + def format_aut_init_footer(self): + buff = [] + buff.append(self.__get_automaton_initialization_footer_string()) + + return buff + + def format_invalid_state(self): + buff = [] + buff.append("#define %s state_max%s\n" % (self.invalid_state_str, self.enum_suffix)) + + return buff + + def format_model(self): + buff = [] + buff += self.format_states_enum() + buff += self.format_invalid_state() + buff += self.format_events_enum() + buff += self.format_automaton_definition() + buff += self.format_aut_init_header() + buff += self.format_aut_init_states_string() + buff += self.format_aut_init_events_string() + buff += self.format_aut_init_function() + buff += self.format_aut_init_initial_state() + buff += self.format_aut_init_final_states() + buff += self.format_aut_init_footer() + + return buff + + def print_model_classic(self): + buff = self.format_model() + print(self.__buff_to_string(buff)) From patchwork Fri Jul 29 09:38:47 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932250 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 7DE13C3F6B0 for ; Fri, 29 Jul 2022 09:40:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235709AbiG2Jka (ORCPT ); Fri, 29 Jul 2022 05:40:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38736 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235707AbiG2JkI (ORCPT ); Fri, 29 Jul 2022 05:40:08 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CCB23863E3; Fri, 29 Jul 2022 02:39:50 -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 ams.source.kernel.org (Postfix) with ESMTPS id D8D2FB826F8; Fri, 29 Jul 2022 09:39:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E94E8C433C1; Fri, 29 Jul 2022 09:39:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087587; bh=qSQyTWfkKzEDzU3CxXWDxGtFFKdu6RDV4KVTqfCnI6A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ar6tLgjYA6OSKTfQv8kSl9NNZzP5rB19A1VcMFl8i3MLzenhPGtTnZ/8IO3zcps+H X4my9vShRlmucX30grVe2mwD7yVPM7MWytO3YSFEL3E9ks7MaP6FHTHPAvnwNDjDty /HdZEqn7betps+7OLi+uDlg1eXdIeqb8de7u2R4H07VlfRRkrNmekq05rRuAZQENlZ 3ClS1w0KNtYj5S2iZYtBrSz5hRLsoFuqsJ+AywBuYkRkDzXX60oXYZSPnhcy9HvnSi ITJnPvVURIB1dU6htKNgVNchXhyC0D9PYeBUIvOrpSRtd0q7ainbhiDGRBEAqK8PVU AhB6eWdo9AMng== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 08/16] Documentation/rv: Add deterministic automaton documentation Date: Fri, 29 Jul 2022 11:38:47 +0200 Message-Id: <387edaed87630bd5eb37c4275045dfd229700aa6.1659052063.git.bristot@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Add documentation about deterministic automaton and its possible representations (formal, graphic, .dot and C). Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- .../trace/rv/deterministic_automata.rst | 184 ++++++++++++++++++ Documentation/trace/rv/index.rst | 1 + tools/verification/dot2/automata.py | 3 + tools/verification/dot2/dot2c | 3 + tools/verification/dot2/dot2c.py | 3 + 5 files changed, 194 insertions(+) create mode 100644 Documentation/trace/rv/deterministic_automata.rst diff --git a/Documentation/trace/rv/deterministic_automata.rst b/Documentation/trace/rv/deterministic_automata.rst new file mode 100644 index 000000000000..d0638f95a455 --- /dev/null +++ b/Documentation/trace/rv/deterministic_automata.rst @@ -0,0 +1,184 @@ +Deterministic Automata +====================== + +Formally, a deterministic automaton, denoted by G, is defined as a quintuple: + + *G* = { *X*, *E*, *f*, x\ :subscript:`0`, X\ :subscript:`m` } + +where: + +- *X* is the set of states; +- *E* is the finite set of events; +- x\ :subscript:`0` is the initial state; +- X\ :subscript:`m` (subset of *X*) is the set of marked (or final) states. +- *f* : *X* x *E* -> *X* $ is the transition function. It defines the state + transition in the occurrence of an event from *E* in the state *X*. In the + special case of deterministic automata, the occurrence of the event in *E* + in a state in *X* has a deterministic next state from *X*. + +For example, a given automaton named 'wip' (wakeup in preemptive) can +be defined as: + +- *X* = { ``preemptive``, ``non_preemptive``} +- *E* = { ``preempt_enable``, ``preempt_disable``, ``sched_waking``} +- x\ :subscript:`0` = ``preemptive`` +- X\ :subscript:`m` = {``preemptive``} +- *f* = + - *f*\ (``preemptive``, ``preempt_disable``) = ``non_preemptive`` + - *f*\ (``non_preemptive``, ``sched_waking``) = ``non_preemptive`` + - *f*\ (``non_preemptive``, ``preempt_enable``) = ``preemptive`` + +One of the benefits of this formal definition is that it can be presented +in multiple formats. For example, using a *graphical representation*, using +vertices (nodes) and edges, which is very intuitive for *operating system* +practitioners, without any loss. + +The previous 'wip' automaton can also be represented as:: + + preempt_enable + +---------------------------------+ + v | + #============# preempt_disable +------------------+ + --> H preemptive H -----------------> | non_preemptive | + #============# +------------------+ + ^ | + | sched_waking | + +--------------+ + +Deterministic Automaton in C +---------------------------- + +In the paper "Efficient formal verification for the Linux kernel", +the authors present a simple way to represent an automaton in C that can +be used as regular code in the Linux kernel. + +For example, the 'wip' automata can be presented as (augmented with comments):: + + /* enum representation of X (set of states) to be used as index */ + enum states { + preemptive = 0, + non_preemptive, + state_max + }; + + #define INVALID_STATE state_max + + /* enum representation of E (set of events) to be used as index */ + enum events { + preempt_disable = 0, + preempt_enable, + sched_waking, + event_max + }; + + struct automaton { + char *state_names[state_max]; // X: the set of states + char *event_names[event_max]; // E: the finite set of events + unsigned char function[state_max][event_max]; // f: transition function + unsigned char initial_state; // x_0: the initial state + bool final_states[state_max]; // X_m: the set of marked states + }; + + struct automaton aut = { + .state_names = { + "preemptive", + "non_preemptive" + }, + .event_names = { + "preempt_disable", + "preempt_enable", + "sched_waking" + }, + .function = { + { non_preemptive, INVALID_STATE, INVALID_STATE }, + { INVALID_STATE, preemptive, non_preemptive }, + }, + .initial_state = preemptive, + .final_states = { 1, 0 }, + }; + +The *transition function* is represented as a matrix of states (lines) and +events (columns), and so the function *f* : *X* x *E* -> *X* can be solved +in O(1). For example:: + + next_state = automaton_wip.function[curr_state][event]; + +Graphviz .dot format +-------------------- + +The Graphviz open-source tool can produce the graphical representation +of an automaton using the (textual) DOT language as the source code. +The DOT format is widely used and can be converted to many other formats. + +For example, this is the 'wip' model in DOT:: + + 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"; + } + } + +This DOT format can be transformed into a bitmap or vectorial image +using the dot utility, or into an ASCII art using graph-easy. For +instance:: + + $ dot -Tsvg -o wip.svg wip.dot + $ graph-easy wip.dot > wip.txt + +dot2c +----- + +dot2c is a utility that can parse a .dot file containing an automaton as +in the example above and automatically convert it to the C representation +presented in [3]. + +For example, having the previous 'wip' model into a file named 'wip.dot', +the following command will transform the .dot file into the C +representation (previously shown) in the 'wip.h' file:: + + $ dot2c wip.dot > wip.h + +The 'wip.h' content is the code sample in section 'Deterministic Automaton +in C'. + +Remarks +------- + +The automata formalism allows modeling discrete event systems (DES) in +multiple formats, suitable for different applications/users. + +For example, the formal description using set theory is better suitable +for automata operations, while the graphical format for human interpretation; +and computer languages for machine execution. + +References +---------- + +Many textbooks cover automata formalism. For a brief introduction see:: + + O'Regan, Gerard. Concise guide to software engineering. Springer, + Cham, 2017. + +For a detailed description, including operations, and application on Discrete +Event Systems (DES), see:: + + Cassandras, Christos G., and Stephane Lafortune, eds. Introduction to discrete + event systems. Boston, MA: Springer US, 2008. + +For the C representation in kernel, see:: + + De Oliveira, Daniel Bristot; Cucinotta, Tommaso; De Oliveira, Romulo + Silva. Efficient formal verification for the Linux kernel. In: + International Conference on Software Engineering and Formal Methods. + Springer, Cham, 2019. p. 315-332. diff --git a/Documentation/trace/rv/index.rst b/Documentation/trace/rv/index.rst index b54e49b1d0de..013a41a410cf 100644 --- a/Documentation/trace/rv/index.rst +++ b/Documentation/trace/rv/index.rst @@ -7,3 +7,4 @@ Runtime Verification :glob: runtime-verification.rst + deterministic_automata.rst diff --git a/tools/verification/dot2/automata.py b/tools/verification/dot2/automata.py index f22e1dff19ce..baffeb960ff0 100644 --- a/tools/verification/dot2/automata.py +++ b/tools/verification/dot2/automata.py @@ -4,6 +4,9 @@ # Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira # # Automata object: parse an automata in dot file digraph format into a python object +# +# For further information, see: +# Documentation/trace/rv/deterministic_automata.rst import ntpath diff --git a/tools/verification/dot2/dot2c b/tools/verification/dot2/dot2c index 8a8cd84bdfcf..3fe89ab88b65 100644 --- a/tools/verification/dot2/dot2c +++ b/tools/verification/dot2/dot2c @@ -9,6 +9,9 @@ # de Oliveira, D. B. and Cucinotta, T. and de Oliveira, R. S. # "Efficient Formal Verification for the Linux Kernel." International # Conference on Software Engineering and Formal Methods. Springer, Cham, 2019. +# +# For further information, see: +# Documentation/trace/rv/deterministic_automata.rst if __name__ == '__main__': from dot2 import dot2c diff --git a/tools/verification/dot2/dot2c.py b/tools/verification/dot2/dot2c.py index bca902eec483..fa73353f7e56 100644 --- a/tools/verification/dot2/dot2c.py +++ b/tools/verification/dot2/dot2c.py @@ -9,6 +9,9 @@ # de Oliveira, D. B. and Cucinotta, T. and de Oliveira, R. S. # "Efficient Formal Verification for the Linux Kernel." International # Conference on Software Engineering and Formal Methods. Springer, Cham, 2019. +# +# For further information, see: +# Documentation/trace/rv/deterministic_automata.rst from dot2.automata import Automata From patchwork Fri Jul 29 09:38:48 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932254 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 87E5AC25B06 for ; Fri, 29 Jul 2022 09:40:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235779AbiG2Jkv (ORCPT ); Fri, 29 Jul 2022 05:40:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40082 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235698AbiG2Jk1 (ORCPT ); Fri, 29 Jul 2022 05:40:27 -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 8F691B8A; Fri, 29 Jul 2022 02:40:09 -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 26D8D61D96; Fri, 29 Jul 2022 09:39:53 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 021A2C433D7; Fri, 29 Jul 2022 09:39:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087592; bh=mG1y3TloQ/WvnZEwTPkdmc9Aeu5nRoK1ZFR7V90MsFw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TQiD7+iWVIViRYKRKmTEPlqjLyQED4YGm5NgjcuatDbY2cFGwl/Xqxzb3tKHYeU/x VQQQMF5V72Z4gZfabaQtsuqx8vdD0x4jXJPkGIaPiSH3BDeQArLhPygW9W+jjpjjHt s9tJ0ZCgB91Xh+3K+X3ha4Tt0DYgY8NdJSxqf5dMJKH68ND1FAxeY+yz9bZEUHVqyl UnFsDW/aEfiLJYfmvX9LM+pvAGFEaP7oHkH2koXVecONnq96leOZ5oHkGz4bt+7ohc A9JuRGHiqr5QGTnEcZACuKbM9y5fwmJbWOldXvha1SMJph9vA7zkQT6A6sXn4mhfQR mBMmoGLw+bg8w== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 09/16] tools/rv: Add dot2k Date: Fri, 29 Jul 2022 11:38:48 +0200 Message-Id: <083b3ae61e5a62c1e2e5d08009baa91f82181618.1659052063.git.bristot@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org transform .dot file into kernel rv monitor usage: dot2k [-h] -d DOT_FILE -t MONITOR_TYPE [-n MODEL_NAME] [-D DESCRIPTION] optional arguments: -h, --help show this help message and exit -d DOT_FILE, --dot DOT_FILE -t MONITOR_TYPE, --monitor_type MONITOR_TYPE -n MODEL_NAME, --model_name MODEL_NAME -D DESCRIPTION, --description DESCRIPTION Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- tools/verification/dot2/Makefile | 5 + tools/verification/dot2/dot2k | 44 +++++ tools/verification/dot2/dot2k.py | 174 ++++++++++++++++++ .../dot2/dot2k_templates/main_global.c | 91 +++++++++ .../dot2/dot2k_templates/main_per_cpu.c | 91 +++++++++ .../dot2/dot2k_templates/main_per_task.c | 91 +++++++++ 6 files changed, 496 insertions(+) create mode 100644 tools/verification/dot2/dot2k create mode 100644 tools/verification/dot2/dot2k.py create mode 100644 tools/verification/dot2/dot2k_templates/main_global.c create mode 100644 tools/verification/dot2/dot2k_templates/main_per_cpu.c create mode 100644 tools/verification/dot2/dot2k_templates/main_per_task.c diff --git a/tools/verification/dot2/Makefile b/tools/verification/dot2/Makefile index 235d182f6b2c..021beb07a521 100644 --- a/tools/verification/dot2/Makefile +++ b/tools/verification/dot2/Makefile @@ -19,3 +19,8 @@ install: $(INSTALL) automata.py -D -m 644 $(DESTDIR)$(PYLIB)/dot2/automata.py $(INSTALL) dot2c.py -D -m 644 $(DESTDIR)$(PYLIB)/dot2/dot2c.py $(INSTALL) dot2c -D -m 755 $(DESTDIR)$(bindir)/ + $(INSTALL) dot2k.py -D -m 644 $(DESTDIR)$(PYLIB)/dot2/dot2k.py + $(INSTALL) dot2k -D -m 755 $(DESTDIR)$(bindir)/ + + mkdir -p ${miscdir}/ + cp -rp dot2k_templates $(DESTDIR)$(miscdir)/ diff --git a/tools/verification/dot2/dot2k b/tools/verification/dot2/dot2k new file mode 100644 index 000000000000..69106f4b7682 --- /dev/null +++ b/tools/verification/dot2/dot2k @@ -0,0 +1,44 @@ +#!/usr/bin/env python3 +# SPDX-License-Identifier: GPL-2.0-only +# +# Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira +# +# dot2k: transform dot files into a monitor for the Linux kernel. + +if __name__ == '__main__': + from dot2.dot2k import dot2k + import argparse + import ntpath + import os + import platform + import sys + import sys + import argparse + + parser = argparse.ArgumentParser(description='transform .dot file into kernel rv monitor') + parser.add_argument('-d', "--dot", dest="dot_file", required=True) + parser.add_argument('-t', "--monitor_type", dest="monitor_type", required=True) + parser.add_argument('-n', "--model_name", dest="model_name", required=False) + parser.add_argument("-D", "--description", dest="description", required=False) + params = parser.parse_args() + + print("Opening and parsing the dot file %s" % params.dot_file) + try: + monitor=dot2k(params.dot_file, params.monitor_type) + except Exception as e: + print('Error: '+ str(e)) + print("Sorry : :-(") + sys.exit(1) + + # easier than using argparse action. + if params.model_name != None: + print(params.model_name) + + print("Writing the monitor into the directory %s" % monitor.name) + monitor.print_files() + print("Almost done, checklist") + print(" - Edit the %s/%s.c to add the instrumentation" % (monitor.name, monitor.name)) + print(" - Edit include/trace/events/rv.h to add the tracepoint entry") + print(" - Move it to the kernel's monitor directory") + print(" - Edit kernel/trace/rv/Makefile") + print(" - Edit kernel/trace/rv/Kconfig") diff --git a/tools/verification/dot2/dot2k.py b/tools/verification/dot2/dot2k.py new file mode 100644 index 000000000000..d85f755e3bc7 --- /dev/null +++ b/tools/verification/dot2/dot2k.py @@ -0,0 +1,174 @@ +#!/usr/bin/env python3 +# SPDX-License-Identifier: GPL-2.0-only +# +# Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira +# +# dot2k: transform dot files into a monitor for the Linux kernel. + +from dot2.dot2c import Dot2c +import platform +import os + +class dot2k(Dot2c): + monitor_types = { "global" : 1, "per_cpu" : 2, "per_task" : 3 } + monitor_templates_dir = "dot2k/rv_templates/" + monitor_type = "per_cpu" + + def __init__(self, file_path, MonitorType): + super().__init__(file_path) + + self.monitor_type = self.monitor_types.get(MonitorType) + if self.monitor_type == None: + raise Exception("Unknown monitor type: %s" % MonitorType) + + self.monitor_type = MonitorType + self.__fill_rv_templates_dir() + self.main_c = self.__open_file(self.monitor_templates_dir + "main_" + MonitorType + ".c") + self.enum_suffix = "_%s" % self.name + + def __fill_rv_templates_dir(self): + + if os.path.exists(self.monitor_templates_dir) == True: + return + + if platform.system() != "Linux": + raise Exception("I can only run on Linux.") + + kernel_path = "/lib/modules/%s/build/tools/verification/dot2/dot2k_templates/" % (platform.release()) + + if os.path.exists(kernel_path) == True: + self.monitor_templates_dir = kernel_path + return + + if os.path.exists("/usr/share/dot2/dot2k_templates/") == True: + self.monitor_templates_dir = "/usr/share/dot2/dot2k_templates/" + return + + raise Exception("Could not find the template directory, do you have the kernel source installed?") + + + def __open_file(self, path): + try: + fd = open(path) + except OSError: + raise Exception("Cannot open the file: %s" % path) + + content = fd.read() + + return content + + def __buff_to_string(self, buff): + string = "" + + for line in buff: + string = string + line + "\n" + + # cut off the last \n + return string[:-1] + + def fill_tracepoint_handlers_skel(self): + buff = [] + for event in self.events: + buff.append("static void handle_%s(void *data, /* XXX: fill header */)" % event) + buff.append("{") + if self.monitor_type == "per_task": + buff.append("\tstruct task_struct *p = /* XXX: how do I get p? */;"); + buff.append("\tda_handle_event_%s(p, %s%s);" % (self.name, event, self.enum_suffix)); + else: + buff.append("\tda_handle_event_%s(%s%s);" % (self.name, event, self.enum_suffix)); + buff.append("}") + buff.append("") + return self.__buff_to_string(buff) + + def fill_tracepoint_attach_probe(self): + buff = [] + for event in self.events: + buff.append("\trv_attach_trace_probe(\"%s\", /* XXX: tracepoint */, handle_%s);" % (self.name, event)) + return self.__buff_to_string(buff) + + def fill_tracepoint_detach_helper(self): + buff = [] + for event in self.events: + buff.append("\trv_detach_trace_probe(\"%s\", /* XXX: tracepoint */, handle_%s);" % (self.name, event)) + return self.__buff_to_string(buff) + + def fill_main_c(self): + main_c = self.main_c + min_type = self.get_minimun_type() + nr_events = self.events.__len__() + tracepoint_handlers = self.fill_tracepoint_handlers_skel() + tracepoint_attach = self.fill_tracepoint_attach_probe() + tracepoint_detach = self.fill_tracepoint_detach_helper() + + main_c = main_c.replace("MIN_TYPE", min_type) + main_c = main_c.replace("MODEL_NAME", self.name) + main_c = main_c.replace("NR_EVENTS", str(nr_events)) + main_c = main_c.replace("TRACEPOINT_HANDLERS_SKEL", tracepoint_handlers) + main_c = main_c.replace("TRACEPOINT_ATTACH", tracepoint_attach) + main_c = main_c.replace("TRACEPOINT_DETACH", tracepoint_detach) + + return main_c + + def fill_model_h_header(self): + buff = [] + buff.append("/*") + buff.append(" * Automatically generated C representation of %s automaton" % (self.name)) + buff.append(" * For further information about this format, see kernel documentation:") + buff.append(" * Documentation/trace/rv/deterministic_automata.rst") + buff.append(" */") + buff.append("") + + return buff + + def fill_model_h(self): + # + # Adjust the definition names + # + self.enum_states_def = "states_%s" % self.name + self.enum_events_def = "events_%s" % self.name + self.struct_automaton_def = "automaton_%s" % self.name + self.var_automaton_def = "automaton_%s" % self.name + + buff = self.fill_model_h_header() + buff += self.format_model() + + return self.__buff_to_string(buff) + + def __create_directory(self): + try: + os.mkdir(self.name) + except FileExistsError: + return + except: + print("Fail creating the output dir: %s" % self.name) + + def __create_file(self, file_name, content): + path = "%s/%s" % (self.name, file_name) + try: + file = open(path, 'w') + except FileExistsError: + return + except: + print("Fail creating file: %s" % path) + + file.write(content) + + file.close() + + def __get_main_name(self): + path = "%s/%s" % (self.name, "main.c") + if os.path.exists(path) == False: + return "main.c" + return "__main.c" + + def print_files(self): + main_c = self.fill_main_c() + model_h = self.fill_model_h() + + self.__create_directory() + + path = "%s.c" % self.name + self.__create_file(path, main_c) + + path = "%s.h" % self.name + self.__create_file(path, model_h) diff --git a/tools/verification/dot2/dot2k_templates/main_global.c b/tools/verification/dot2/dot2k_templates/main_global.c new file mode 100644 index 000000000000..f4b712dbc92e --- /dev/null +++ b/tools/verification/dot2/dot2k_templates/main_global.c @@ -0,0 +1,91 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include + +#define MODULE_NAME "MODEL_NAME" + +/* + * XXX: include required tracepoint headers, e.g., + * #include + */ +#include + +/* + * This is the self-generated part of the monitor. Generally, there is no need + * to touch this section. + */ +#include "MODEL_NAME.h" + +/* + * Declare the deterministic automata monitor. + * + * The rv monitor reference is needed for the monitor declaration. + */ +struct rv_monitor rv_MODEL_NAME; +DECLARE_DA_MON_GLOBAL(MODEL_NAME, MIN_TYPE); + +/* + * 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. + * + */ +TRACEPOINT_HANDLERS_SKEL +static int enable_MODEL_NAME(void) +{ + int retval; + + retval = da_monitor_init_MODEL_NAME(); + if (retval) + return retval; + +TRACEPOINT_ATTACH + + return 0; +} + +static void disable_MODEL_NAME(void) +{ + rv_MODEL_NAME.enabled = 0; + +TRACEPOINT_DETACH + + da_monitor_destroy_MODEL_NAME(); +} + +/* + * This is the monitor register section. + */ +struct rv_monitor rv_MODEL_NAME = { + .name = "MODEL_NAME", + .description = "auto-generated MODEL_NAME", + .enable = enable_MODEL_NAME, + .disable = disable_MODEL_NAME, + .reset = da_monitor_reset_all_MODEL_NAME, + .enabled = 0, +}; + +static int register_MODEL_NAME(void) +{ + rv_register_monitor(&rv_MODEL_NAME); + return 0; +} + +static void unregister_MODEL_NAME(void) +{ + rv_unregister_monitor(&rv_MODEL_NAME); +} + +module_init(register_MODEL_NAME); +module_exit(unregister_MODEL_NAME); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("dot2k: auto-generated"); +MODULE_DESCRIPTION("MODEL_NAME"); diff --git a/tools/verification/dot2/dot2k_templates/main_per_cpu.c b/tools/verification/dot2/dot2k_templates/main_per_cpu.c new file mode 100644 index 000000000000..4080d1ca3354 --- /dev/null +++ b/tools/verification/dot2/dot2k_templates/main_per_cpu.c @@ -0,0 +1,91 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include + +#define MODULE_NAME "MODEL_NAME" + +/* + * XXX: include required tracepoint headers, e.g., + * #include + */ +#include + +/* + * This is the self-generated part of the monitor. Generally, there is no need + * to touch this section. + */ +#include "MODEL_NAME.h" + +/* + * Declare the deterministic automata monitor. + * + * The rv monitor reference is needed for the monitor declaration. + */ +struct rv_monitor rv_MODEL_NAME; +DECLARE_DA_MON_PER_CPU(MODEL_NAME, MIN_TYPE); + +/* + * 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. + * + */ +TRACEPOINT_HANDLERS_SKEL +static int enable_MODEL_NAME(void) +{ + int retval; + + retval = da_monitor_init_MODEL_NAME(); + if (retval) + return retval; + +TRACEPOINT_ATTACH + + return 0; +} + +static void disable_MODEL_NAME(void) +{ + rv_MODEL_NAME.enabled = 0; + +TRACEPOINT_DETACH + + da_monitor_destroy_MODEL_NAME(); +} + +/* + * This is the monitor register section. + */ +struct rv_monitor rv_MODEL_NAME = { + .name = "MODEL_NAME", + .description = "auto-generated MODEL_NAME", + .enable = enable_MODEL_NAME, + .disable = disable_MODEL_NAME, + .reset = da_monitor_reset_all_MODEL_NAME, + .enabled = 0, +}; + +static int register_MODEL_NAME(void) +{ + rv_register_monitor(&rv_MODEL_NAME); + return 0; +} + +static void unregister_MODEL_NAME(void) +{ + rv_unregister_monitor(&rv_MODEL_NAME); +} + +module_init(register_MODEL_NAME); +module_exit(unregister_MODEL_NAME); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("dot2k: auto-generated"); +MODULE_DESCRIPTION("MODEL_NAME"); diff --git a/tools/verification/dot2/dot2k_templates/main_per_task.c b/tools/verification/dot2/dot2k_templates/main_per_task.c new file mode 100644 index 000000000000..89197175384f --- /dev/null +++ b/tools/verification/dot2/dot2k_templates/main_per_task.c @@ -0,0 +1,91 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include + +#define MODULE_NAME "MODEL_NAME" + +/* + * XXX: include required tracepoint headers, e.g., + * #include + */ +#include + +/* + * This is the self-generated part of the monitor. Generally, there is no need + * to touch this section. + */ +#include "MODEL_NAME.h" + +/* + * Declare the deterministic automata monitor. + * + * The rv monitor reference is needed for the monitor declaration. + */ +struct rv_monitor rv_MODEL_NAME; +DECLARE_DA_MON_PER_TASK(MODEL_NAME, MIN_TYPE); + +/* + * 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. + * + */ +TRACEPOINT_HANDLERS_SKEL +static int enable_MODEL_NAME(void) +{ + int retval; + + retval = da_monitor_init_MODEL_NAME(); + if (retval) + return retval; + +TRACEPOINT_ATTACH + + return 0; +} + +static void disable_MODEL_NAME(void) +{ + rv_MODEL_NAME.enabled = 0; + +TRACEPOINT_DETACH + + da_monitor_destroy_MODEL_NAME(); +} + +/* + * This is the monitor register section. + */ +struct rv_monitor rv_MODEL_NAME = { + .name = "MODEL_NAME", + .description = "auto-generated MODEL_NAME", + .enable = enable_MODEL_NAME, + .disable = disable_MODEL_NAME, + .reset = da_monitor_reset_all_MODEL_NAME, + .enabled = 0, +}; + +static int register_MODEL_NAME(void) +{ + rv_register_monitor(&rv_MODEL_NAME); + return 0; +} + +static void unregister_MODEL_NAME(void) +{ + rv_unregister_monitor(&rv_MODEL_NAME); +} + +module_init(register_MODEL_NAME); +module_exit(unregister_MODEL_NAME); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("dot2k: auto-generated"); +MODULE_DESCRIPTION("MODEL_NAME"); From patchwork Fri Jul 29 09:38:49 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932251 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 074D1C19F2B for ; Fri, 29 Jul 2022 09:40:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235767AbiG2Jks (ORCPT ); Fri, 29 Jul 2022 05:40:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235900AbiG2Jk2 (ORCPT ); Fri, 29 Jul 2022 05:40:28 -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 960351134; Fri, 29 Jul 2022 02:40:11 -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 335E361DAB; Fri, 29 Jul 2022 09:39:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0AC99C433C1; Fri, 29 Jul 2022 09:39:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087597; bh=l07iqYvDCIzM91o7dR81Qc67Abtk1LTX8NhlRBkyDUE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JB4l0TfUxKC7nBWmAHvg+zvn+y4I13Ez97GrPMI+V+TIxTNpJCWKIwdLyBF+3Q/EK UtkHEPNXYVphBvfiwDCn1lfnsKA/S49YeSnKHUMkdZrZVCXnTMCvxdZTGIyBjpI+Rq edez/pgumo5NKX5f6NTXidY8I/KP9sEGPt5bH0jtAf5QBb6YWqIz4xO3fLOQiyqDTm AcYbOUvFeN/U2rP/eIKUFL74P/BXmq2xmhyMgrH+du7y3yJq7+5mG8v1k+vT0hfjAh RIULwz9Uql1HH25T6bP1xHXuxs5q1dMMlZL00CaqSNrz2CGddOmFrIGbOR5vjiuPBg 1WVqLaPb/NTpQ== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 10/16] Documentation/rv: Add deterministic automata monitor synthesis documentation Date: Fri, 29 Jul 2022 11:38:49 +0200 Message-Id: <7873bdb7b2e5d2bc0b2eb6ca0b324af9a0ba27a0.1659052063.git.bristot@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Add the da_monitor_synthesis.rst introduces some concepts behind the Deterministic Automata (DA) monitor synthesis and interface. Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- .../trace/rv/da_monitor_synthesis.rst | 147 ++++++++++++++++++ Documentation/trace/rv/index.rst | 1 + include/rv/da_monitor.h | 3 + tools/verification/dot2/dot2k | 3 + tools/verification/dot2/dot2k.py | 3 + 5 files changed, 157 insertions(+) create mode 100644 Documentation/trace/rv/da_monitor_synthesis.rst diff --git a/Documentation/trace/rv/da_monitor_synthesis.rst b/Documentation/trace/rv/da_monitor_synthesis.rst new file mode 100644 index 000000000000..0dbdcd1e62b9 --- /dev/null +++ b/Documentation/trace/rv/da_monitor_synthesis.rst @@ -0,0 +1,147 @@ +Deterministic Automata Monitor Synthesis +======================================== + +The starting point for the application of runtime verification (RV) technics +is the *specification* or *modeling* of the desired (or undesired) behavior +of the system under scrutiny. + +The formal representation needs to be then *synthesized* into a *monitor* +that can then be used in the analysis of the trace of the system. The +*monitor* connects to the system via an *instrumentation* that converts +the events from the *system* to the events of the *specification*. + + +In Linux terms, the runtime verification monitors are encapsulated inside +the *RV monitor* abstraction. The RV monitor includes a set of instances +of the monitor (per-cpu monitor, per-task monitor, and so on), the helper +functions that glue the monitor to the system reference model, and the +trace output as a reaction to event parsing and exceptions, as depicted +below:: + + Linux +----- RV Monitor ----------------------------------+ Formal + Realm | | Realm + +-------------------+ +----------------+ +-----------------+ + | Linux kernel | | Monitor | | Reference | + | Tracing | -> | Instance(s) | <- | Model | + | (instrumentation) | | (verification) | | (specification) | + +-------------------+ +----------------+ +-----------------+ + | | | + | V | + | +----------+ | + | | Reaction | | + | +--+--+--+-+ | + | | | | | + | | | +-> trace output ? | + +------------------------|--|----------------------+ + | +----> panic ? + +-------> + +DA monitor synthesis +-------------------- + +The synthesis of automata-based models into the Linux *RV monitor* abstraction +is automated by the dot2k tool and the rv/da_monitor.h header file that +contains a set of macros that automatically generate the monitor's code. + +dot2k +----- + +The dot2k utility leverages dot2c by converting an automaton model in +the DOT format into the C representation [1] and creating the skeleton of +a kernel monitor in C. + +For example, it is possible to transform the wip.dot model present in +[1] into a per-cpu monitor with the following command:: + + $ dot2k -d wip.dot -t per_cpu + +This will create a directory named wip/ with the following files: + +- wip.h: the wip model in C +- wip.c: the RV monitor + +The wip.c file contains the monitor declaration and the starting point for +the system instrumentation. + +Monitor macros +-------------- + +The rv/da_monitor.h enables automatic code generation for the *Monitor +Instance(s)* using C macros. + +The benefits of the usage of macro for monitor synthesis are 3-fold as it: + +- Reduces the code duplication; +- Facilitates the bug fix/improvement; +- Avoids the case of developers changing the core of the monitor code + to manipulate the model in a (let's say) non-standard way. + +This initial implementation presents three different types of monitor instances: + +- ``#define DECLARE_DA_MON_GLOBAL(name, type)`` +- ``#define DECLARE_DA_MON_PER_CPU(name, type)`` +- ``#define DECLARE_DA_MON_PER_TASK(name, type)`` + +The first declares the functions for a global deterministic automata monitor, +the second for monitors with per-cpu instances, and the third with per-task +instances. + +In all cases, the 'name' argument is a string that identifies the monitor, and +the 'type' argument is the data type used by dot2k on the representation of +the model in C. + +For example, the wip model with two states and three events can be +stored in an 'unsigned char' type. Considering that the preemption control +is a per-cpu behavior, the monitor declaration in the 'wip.c' file is:: + + DECLARE_DA_MON_PER_CPU(wip, unsigned char); + +The monitor is executed by sending events to be processed via the functions +presented below:: + + da_handle_event_$(MONITOR_NAME)($(event from event enum)); + da_handle_start_event_$(MONITOR_NAME)($(event from event enum)); + da_handle_start_run_event_$(MONITOR_NAME)($(event from event enum)); + +The function ``da_handle_event_$(MONITOR_NAME)()`` is the regular case where +the event will be processed if the monitor is processing events. + +When a monitor is enabled, it is placed in the initial state of the automata. +However, the monitor does not know if the system is in the *initial state*. + +The ``da_handle_start_event_$(MONITOR_NAME)()`` function is used to notify the +monitor that the system is returning to the initial state, so the monitor can +start monitoring the next event. + +The ``da_handle_start_run_event_$(MONITOR_NAME)()`` function is used to notify +the monitor that the system is known to be in the initial state, so the +monitor can start monitoring and monitor the current event. + +Using the wip model as example, the events "preempt_disable" and +"sched_waking" should be sent to monitor, respectively, via [2]:: + + da_handle_event_wip(preempt_disable_wip); + da_handle_event_wip(sched_waking_wip); + +While the event "preempt_enabled" will use:: + + da_handle_start_event_wip(preempt_enable_wip); + +To notify the monitor that the system will be returning to the initial state, +so the system and the monitor should be in sync. + +Final remarks +------------- + +With the monitor synthesis in place using the rv/da_monitor.h and +dot2k, the developer's work should be limited to the instrumentation +of the system, increasing the confidence in the overall approach. + +[1] For details about deterministic automata format and the translation +from one representation to another, see:: + + Documentation/trace/rv/deterministic_automata.rst + +[2] dot2k appends the monitor's name suffix to the events enums to +avoid conflicting variables when exporting the global vmlinux.h +use by BPF programs. diff --git a/Documentation/trace/rv/index.rst b/Documentation/trace/rv/index.rst index 013a41a410cf..46d47f33052c 100644 --- a/Documentation/trace/rv/index.rst +++ b/Documentation/trace/rv/index.rst @@ -8,3 +8,4 @@ Runtime Verification runtime-verification.rst deterministic_automata.rst + da_monitor_synthesis.rst diff --git a/include/rv/da_monitor.h b/include/rv/da_monitor.h index 001bc298289f..9eb75683e012 100644 --- a/include/rv/da_monitor.h +++ b/include/rv/da_monitor.h @@ -6,6 +6,9 @@ * with automata models in C generated by the dot2k tool. * * The dot2k tool is available at tools/verification/dot2k/ + * + * For further information, see: + * Documentation/trace/rv/da_monitor_synthesis.rst */ #include diff --git a/tools/verification/dot2/dot2k b/tools/verification/dot2/dot2k index 69106f4b7682..9dcd38abe20a 100644 --- a/tools/verification/dot2/dot2k +++ b/tools/verification/dot2/dot2k @@ -4,6 +4,9 @@ # Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira # # dot2k: transform dot files into a monitor for the Linux kernel. +# +# For further information, see: +# Documentation/trace/rv/da_monitor_synthesis.rst if __name__ == '__main__': from dot2.dot2k import dot2k diff --git a/tools/verification/dot2/dot2k.py b/tools/verification/dot2/dot2k.py index d85f755e3bc7..016550fccf1f 100644 --- a/tools/verification/dot2/dot2k.py +++ b/tools/verification/dot2/dot2k.py @@ -4,6 +4,9 @@ # Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira # # dot2k: transform dot files into a monitor for the Linux kernel. +# +# For further information, see: +# Documentation/trace/rv/da_monitor_synthesis.rst from dot2.dot2c import Dot2c import platform From patchwork Fri Jul 29 09:38:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932252 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 47FB2C19F2D for ; Fri, 29 Jul 2022 09:40:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235820AbiG2Jku (ORCPT ); Fri, 29 Jul 2022 05:40:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235902AbiG2Jk2 (ORCPT ); Fri, 29 Jul 2022 05:40:28 -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 0E508218C; Fri, 29 Jul 2022 02:40:11 -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 3528261D97; Fri, 29 Jul 2022 09:40:03 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F37AC4347C; Fri, 29 Jul 2022 09:39:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087602; bh=CCZnCiGIC2XrY3X8NeTs1iYP+uKvFbdPaa4pIVTAjAw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fVxasy3v50AjSlKBz9atN+FLSf8+QBuP8/8AOgiPUMVxIuyYrSMinl1aQndO17lLy b13gTSdELcCTApA08Ddd6tx7zpXPIRhhTkTT0ZGgux2HDS2mNXkzrjKD5nRcYsGaad E2Bym9HozZgJRa5k3xV9m7dk0tjyTzgZoWu+NoeAn5fGuyCua1K1DebDM7POHXs3wq nmPPJ+ssAs8rIRDPfBygEoofew6JOexhjV8Jtk1o9dJIw3gKKxi46Yhm11gE3djoI2 QF/5/5wRUhLh1CJ3ayj1pScvx1VkchMhNgAHuUUEyzHAchjUMi3cjA0HH97lULXQHC 4WnQ/gOYV251A== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 11/16] Documentation/rv: Add deterministic automata instrumentation documentation Date: Fri, 29 Jul 2022 11:38:50 +0200 Message-Id: <0557d5c68e2fc252f2643c2cc5295a67e2b73277.1659052063.git.bristot@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Add the da_monitor_instrumentation.rst. It describes the basics of RV monitor instrumentation. Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- .../trace/rv/da_monitor_instrumentation.rst | 171 ++++++++++++++++++ Documentation/trace/rv/index.rst | 1 + 2 files changed, 172 insertions(+) create mode 100644 Documentation/trace/rv/da_monitor_instrumentation.rst diff --git a/Documentation/trace/rv/da_monitor_instrumentation.rst b/Documentation/trace/rv/da_monitor_instrumentation.rst new file mode 100644 index 000000000000..6c67c7b57811 --- /dev/null +++ b/Documentation/trace/rv/da_monitor_instrumentation.rst @@ -0,0 +1,171 @@ +Deterministic Automata Instrumentation +====================================== + +The RV monitor file created by dot2k, with the name "$MODEL_NAME.c" +includes a section dedicated to instrumentation. + +In the example of the wip.dot monitor created on [1], it will look like:: + + /* + * 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 */) + { + da_handle_event_wip(preempt_disable_wip); + } + + static void handle_preempt_enable(void *data, /* XXX: fill header */) + { + da_handle_event_wip(preempt_enable_wip); + } + + static void handle_sched_waking(void *data, /* XXX: fill header */) + { + da_handle_event_wip(sched_waking_wip); + } + + static int enable_wip(void) + { + int retval; + + retval = da_monitor_init_wip(); + 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); + + return 0; + } + +The comment at the top of the section explains the general idea: the +instrumentation section translates *kernel events* into the *model's +event*. + +Tracing callback functions +-------------------------- + +The first three functions are the starting point of the callback *handler +functions* for each of the three events from the wip model. The developer +does not necessarily need to use them: they are just starting points. + +Using the example of:: + + void handle_preempt_disable(void *data, /* XXX: fill header */) + { + da_handle_event_wip(preempt_disable_wip); + } + +The preempt_disable event from the model connects directly to the +preemptirq:preempt_disable. The preemptirq:preempt_disable event +has the following signature, from include/trace/events/preemptirq.h:: + + TP_PROTO(unsigned long ip, unsigned long parent_ip) + +Hence, the handle_preempt_disable() function will look like:: + + void handle_preempt_disable(void *data, unsigned long ip, unsigned long parent_ip) + +In this case, the kernel event translates one to one with the automata +event, and indeed, no other change is required for this function. + +The next handler function, handle_preempt_enable() has the same argument +list from the handle_preempt_disable(). The difference is that the +preempt_enable event will be used to synchronize the system to the model. + +Initially, the *model* is placed in the initial state. However, the *system* +might or might not be in the initial state. The monitor cannot start +processing events until it knows that the system has reached the initial state. +Otherwise, the monitor and the system could be out-of-sync. + +Looking at the automata definition, it is possible to see that the system +and the model are expected to return to the initial state after the +preempt_enable execution. Hence, it can be used to synchronize the +system and the model at the initialization of the monitoring section. + +The start is informed via a special handle function, the +"da_handle_start_event_$(MONITOR_NAME)(event)", in this case:: + + da_handle_start_event_wip(preempt_enable_wip); + +So, the callback function will look like:: + + void handle_preempt_enable(void *data, unsigned long ip, unsigned long parent_ip) + { + da_handle_start_event_wip(preempt_enable_wip); + } + +Finally, the "handle_sched_waking()" will look like:: + + void handle_sched_waking(void *data, struct task_struct *task) + { + da_handle_event_wip(sched_waking_wip); + } + +And the explanation is left for the reader as an exercise. + +enable and disable functions +---------------------------- + +dot2k automatically creates two special functions:: + + enable_$(MONITOR_NAME)() + disable_$(MONITOR_NAME)() + +These functions are called when the monitor is enabled and disabled, +respectively. + +They should be used to *attach* and *detach* the instrumentation to the running +system. The developer must add to the relative function all that is needed to +*attach* and *detach* its monitor to the system. + +For the wip case, these functions were named:: + + enable_wip() + disable_wip() + +But no change was required because: by default, these functions *attach* and +*detach* the tracepoints_to_attach, which was enough for this case. + +Instrumentation helpers +----------------------- + +To complete the instrumentation, the *handler functions* need to be attached to a +kernel event, at the monitoring enable phase. + +The RV interface also facilitates this step. For example, the macro "rv_attach_trace_probe()" +is used to connect the wip model events to the relative kernel event. dot2k automatically +adds "rv_attach_trace_probe()" function call for each model event in the enable phase, as +a suggestion. + +For example, from the wip sample model:: + + static int enable_wip(void) + { + int retval; + + retval = da_monitor_init_wip(); + if (retval) + return retval; + + 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", /* XXX: tracepoint */, handle_preempt_disable); + + return 0; + } + +The probes then need to be detached at the disable phase. + +[1] The wip model is presented in:: + + Documentation/trace/rv/deterministic_automata.rst + +The wip monitor is presented in:: + + Documentation/trace/rv/da_monitor_synthesis.rst diff --git a/Documentation/trace/rv/index.rst b/Documentation/trace/rv/index.rst index 46d47f33052c..db2ae3f90b90 100644 --- a/Documentation/trace/rv/index.rst +++ b/Documentation/trace/rv/index.rst @@ -9,3 +9,4 @@ Runtime Verification runtime-verification.rst deterministic_automata.rst da_monitor_synthesis.rst + da_monitor_instrumentation.rst From patchwork Fri Jul 29 09:38:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932253 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 7BD59C3F6B0 for ; Fri, 29 Jul 2022 09:40:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235759AbiG2Jkt (ORCPT ); Fri, 29 Jul 2022 05:40:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40248 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235704AbiG2Jk3 (ORCPT ); Fri, 29 Jul 2022 05:40:29 -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 901DD2DE7; Fri, 29 Jul 2022 02:40:12 -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 3054D61D43; Fri, 29 Jul 2022 09:40:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 128B8C433C1; Fri, 29 Jul 2022 09:40:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087607; bh=GB41tQKICNtDkQFxA/QWse4BCeG2/JC8OIwADKGp+BU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pvP9bRcs4U6a5SmepAWpwIoR+qz/7LIz2zGFSZPptkjsfslE3iQK58d14RCFnGdvd SNMdS54F88ov9m1UE0re11B6pCEubY3CVmJVQuYEiwxo7CF3LIaPCGmVYVnpnsi2in Gyxhlud23+XUFtL1t7z8j/lkJxb+bqn++t52TeTmVxAColqge5i73VNJ+FSSpQWbdB 8e9A2TmuFyjWCjvezAUmJC5jqEd+VPAdSToszJxjmYcFZWz6E1IG/+NLCRU56YlOKP yOhjvQ3ahWd+3LAWOcRJfNqNSGbyWWtV5ziZxzqzP65MaqKqqoUidjIJ33XPsOf617 IfNf4ZERkj+oQ== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 12/16] rv/monitor: Add the wip monitor skeleton created by dot2k Date: Fri, 29 Jul 2022 11:38:51 +0200 Message-Id: <5eb7a9118917e8a814c5e49853a72fc62be0a101.1659052063.git.bristot@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org THIS CODE IS NOT LINKED TO THE MAKEFILE. This model does not compile because it lacks the instrumentation part, which will be added next. In the typical case, there will be only one patch, but it was split into two patches for educational purposes. This is the direct output this command line: $ dot2k -d tools/verification/models/wip.dot -t per_cpu Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- kernel/trace/rv/monitors/wip/wip.c | 109 +++++++++++++++++++++++++++++ kernel/trace/rv/monitors/wip/wip.h | 46 ++++++++++++ 2 files changed, 155 insertions(+) create mode 100644 kernel/trace/rv/monitors/wip/wip.c create mode 100644 kernel/trace/rv/monitors/wip/wip.h diff --git a/kernel/trace/rv/monitors/wip/wip.c b/kernel/trace/rv/monitors/wip/wip.c new file mode 100644 index 000000000000..79a054ca0cde --- /dev/null +++ b/kernel/trace/rv/monitors/wip/wip.c @@ -0,0 +1,109 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include + +#define MODULE_NAME "wip" + +/* + * XXX: include required tracepoint headers, e.g., + * #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 */) +{ + da_handle_event_wip(preempt_disable_wip); +} + +static void handle_preempt_enable(void *data, /* XXX: fill header */) +{ + da_handle_event_wip(preempt_enable_wip); +} + +static void handle_sched_waking(void *data, /* XXX: fill header */) +{ + da_handle_event_wip(sched_waking_wip); +} + +static int enable_wip(void) +{ + int retval; + + retval = da_monitor_init_wip(); + 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); + + return 0; +} + +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); + + da_monitor_destroy_wip(); +} + +/* + * This is the monitor register section. + */ +struct rv_monitor rv_wip = { + .name = "wip", + .description = "auto-generated wip", + .enable = enable_wip, + .disable = disable_wip, + .reset = da_monitor_reset_all_wip, + .enabled = 0, +}; + +static int register_wip(void) +{ + rv_register_monitor(&rv_wip); + return 0; +} + +static void unregister_wip(void) +{ + rv_unregister_monitor(&rv_wip); +} + +module_init(register_wip); +module_exit(unregister_wip); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("dot2k: auto-generated"); +MODULE_DESCRIPTION("wip"); diff --git a/kernel/trace/rv/monitors/wip/wip.h b/kernel/trace/rv/monitors/wip/wip.h new file mode 100644 index 000000000000..c1c47e2305ef --- /dev/null +++ b/kernel/trace/rv/monitors/wip/wip.h @@ -0,0 +1,46 @@ +/* + * Automatically generated C representation of wip automaton + * For further information about this format, see kernel documentation: + * Documentation/trace/rv/deterministic_automata.rst + */ + +enum states_wip { + preemptive_wip = 0, + non_preemptive_wip, + state_max_wip +}; + +#define INVALID_STATE state_max_wip + +enum events_wip { + preempt_disable_wip = 0, + preempt_enable_wip, + sched_waking_wip, + event_max_wip +}; + +struct automaton_wip { + char *state_names[state_max_wip]; + char *event_names[event_max_wip]; + unsigned char function[state_max_wip][event_max_wip]; + unsigned char initial_state; + bool final_states[state_max_wip]; +}; + +struct automaton_wip automaton_wip = { + .state_names = { + "preemptive", + "non_preemptive" + }, + .event_names = { + "preempt_disable", + "preempt_enable", + "sched_waking" + }, + .function = { + { non_preemptive_wip, INVALID_STATE, INVALID_STATE }, + { INVALID_STATE, preemptive_wip, non_preemptive_wip }, + }, + .initial_state = preemptive_wip, + .final_states = { 1, 0 }, +}; From patchwork Fri Jul 29 09:38:52 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932255 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 8E5E0C25B0D for ; 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d=kernel.org; s=k20201202; t=1659087612; bh=dj96BZIWJRFSyU3Wmlz0UIBl49rvUcM8WuQck9gQxYY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=epUrMPxCfnflptBlDFgKjx5Rn+ypo5PDC9cQ50jpnUOMFv7d0sFdSAdKHlB57di/2 5xxP3vG1kbr78ETs1F9+kAKFf5WRlxEokA3q4BD18+kci/hCcfSYDiW4Us3YpNXo54 rkr2Mumx4Zbx+Yd6PDRxCjGRV69dg47xkso0ZvJVWlZZhSs4rE7/k4h3J77La83+DR 6dPLjbzCa1eAMQCJHmZYyjnsM1Ws3192lcCB6Pf0faVsiTwyQGYPnGYhOAe+9Bl0zP eUEAYMQbcdASAbwsTFV8nWFRcUaobSK0dNWCm+KjbOlgKZVrMG4pNEpKq11ldOn7bj F7cped17eDrmA== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 13/16] rv/monitor: Add the wip monitor Date: Fri, 29 Jul 2022 11:38:52 +0200 Message-Id: X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org 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. Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- 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"; + } +} From patchwork Fri Jul 29 09:38:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932257 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 94EFDC3F6B0 for ; Fri, 29 Jul 2022 09:41:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236020AbiG2JlT (ORCPT ); Fri, 29 Jul 2022 05:41:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235993AbiG2Jkq (ORCPT ); Fri, 29 Jul 2022 05:40:46 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9C9C75004A; Fri, 29 Jul 2022 02:40:28 -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 ams.source.kernel.org (Postfix) with ESMTPS id E5EC6B8267B; Fri, 29 Jul 2022 09:40:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1DA3EC43142; Fri, 29 Jul 2022 09:40:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087617; bh=7ki6Q2Ml1rGm+VkjegkEdRM3Ii0a4PDuPinI0FDioOc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LO8d5In6gJn0lgcP8XLdE1YveisKD/8AwNssAgbmf9nEMIxF3VbrXcN5oGpXs3T1c vgWPMncQ4EjC8yveOgux8SnRxmz+aW/xOPe+kfw7T2jblHULJYmGhYu3cRhf21UXIU OTqtSRGhqRddGrEQGuDauBK48huUo1gNyIMNtWFe1R4Cj/alsQqlJ/Ug5Z3ZnG5c2R jakT6gq0AdXhnGkrlf60Ee2l91u9xK55/iwdgUf7w52zuVcu3n9QIiyCGBQ3dAWF6F qLvt/VM4DPNe/VpY1iPYGVK4vvB4gZU0WaX0rw3Nj4fh/WaKZ7ncFfdlju7xejtRuc QQzJPbxTDLGoQ== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 14/16] rv/monitor: Add the wwnr monitor Date: Fri, 29 Jul 2022 11:38:53 +0200 Message-Id: <473c0fc39967250fdebcff8b620311c11dccad30.1659052063.git.bristot@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Per task wakeup while not running (wwnr) monitor. This model is broken, the reason is that a task can be running in the processor without being set as RUNNABLE. Think about a task about to sleep: 1: set_current_state(TASK_UNINTERRUPTIBLE); 2: schedule(); And then imagine an IRQ happening in between the lines one and two, waking the task up. BOOM, the wakeup will happen while the task is running. Q: Why do we need this model, so? A: To test the reactors. Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- Documentation/trace/rv/index.rst | 1 + Documentation/trace/rv/monitor_wwnr.rst | 45 +++++++++++++ include/trace/events/rv.h | 12 ++++ kernel/trace/rv/Kconfig | 12 ++++ kernel/trace/rv/Makefile | 1 + kernel/trace/rv/monitors/wwnr/wwnr.c | 87 +++++++++++++++++++++++++ kernel/trace/rv/monitors/wwnr/wwnr.h | 46 +++++++++++++ tools/verification/models/wwnr.dot | 16 +++++ 8 files changed, 220 insertions(+) create mode 100644 Documentation/trace/rv/monitor_wwnr.rst create mode 100644 kernel/trace/rv/monitors/wwnr/wwnr.c create mode 100644 kernel/trace/rv/monitors/wwnr/wwnr.h create mode 100644 tools/verification/models/wwnr.dot diff --git a/Documentation/trace/rv/index.rst b/Documentation/trace/rv/index.rst index 4cb71ed628b8..15fa966102c0 100644 --- a/Documentation/trace/rv/index.rst +++ b/Documentation/trace/rv/index.rst @@ -11,3 +11,4 @@ Runtime Verification da_monitor_synthesis.rst da_monitor_instrumentation.rst monitor_wip.rst + monitor_wwnr.rst diff --git a/Documentation/trace/rv/monitor_wwnr.rst b/Documentation/trace/rv/monitor_wwnr.rst new file mode 100644 index 000000000000..80f1777b85aa --- /dev/null +++ b/Documentation/trace/rv/monitor_wwnr.rst @@ -0,0 +1,45 @@ +Monitor wwnr +============ + +- Name: wwrn - wakeup while not running +- Type: per-task deterministic automaton +- Author: Daniel Bristot de Oliveira + +Description +----------- + +This is a per-task sample monitor, with the following +definition:: + + | + | + v + wakeup +-------------+ + +--------- | | + | | not_running | + +--------> | | <+ + +-------------+ | + | | + | switch_in | switch_out + v | + +-------------+ | + | running | -+ + +-------------+ + +This model is borken, the reason is that a task can be running +in the processor without being set as RUNNABLE. Think about a +task about to sleep:: + + 1: set_current_state(TASK_UNINTERRUPTIBLE); + 2: schedule(); + +And then imagine an IRQ happening in between the lines one and two, +waking the task up. BOOM, the wakeup will happen while the task is +running. + +- Why do we need this model, so? +- To test the reactors. + +Specification +------------- +Grapviz Dot file in tools/verification/models/wwnr.dot diff --git a/include/trace/events/rv.h b/include/trace/events/rv.h index e972f27d8df3..56592da9301c 100644 --- a/include/trace/events/rv.h +++ b/include/trace/events/rv.h @@ -122,6 +122,18 @@ DECLARE_EVENT_CLASS(error_da_monitor_id, __entry->event, __entry->state) ); + +#ifdef CONFIG_RV_MON_WWNR +/* id is the pid of the task */ +DEFINE_EVENT(event_da_monitor_id, event_wwnr, + TP_PROTO(int id, char *state, char *event, char *next_state, bool final_state), + TP_ARGS(id, state, event, next_state, final_state)); + +DEFINE_EVENT(error_da_monitor_id, error_wwnr, + TP_PROTO(int id, char *state, char *event), + TP_ARGS(id, state, event)); +#endif /* CONFIG_RV_MON_WWNR */ + #endif /* CONFIG_DA_MON_EVENTS_ID */ #endif /* _TRACE_RV_H */ diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig index e50f3346164a..b259d6e8dc7c 100644 --- a/kernel/trace/rv/Kconfig +++ b/kernel/trace/rv/Kconfig @@ -38,6 +38,18 @@ config RV_MON_WIP For further information, see: Documentation/trace/rv/monitor_wip.rst +config RV_MON_WWNR + depends on RV + select DA_MON_EVENTS_ID + bool "wwnr monitor" + help + Enable wwnr (wakeup while not running) sample monitor, this is a + sample monitor that illustrates the usage of per-task monitor. + The model is borken on purpose: it serves to test reactors. + + For further information, see: + Documentation/trace/rv/monitor_wwnr.rst + config RV_REACTORS bool "Runtime verification reactors" default y diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile index b41109d2750a..af0ff9a46418 100644 --- a/kernel/trace/rv/Makefile +++ b/kernel/trace/rv/Makefile @@ -3,3 +3,4 @@ obj-$(CONFIG_RV) += rv.o obj-$(CONFIG_RV_REACTORS) += rv_reactors.o obj-$(CONFIG_RV_MON_WIP) += monitors/wip/wip.o +obj-$(CONFIG_RV_MON_WWNR) += monitors/wwnr/wwnr.o diff --git a/kernel/trace/rv/monitors/wwnr/wwnr.c b/kernel/trace/rv/monitors/wwnr/wwnr.c new file mode 100644 index 000000000000..599225d9cf38 --- /dev/null +++ b/kernel/trace/rv/monitors/wwnr/wwnr.c @@ -0,0 +1,87 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include + +#define MODULE_NAME "wwnr" + +#include +#include + +#include "wwnr.h" + +struct rv_monitor rv_wwnr; +DECLARE_DA_MON_PER_TASK(wwnr, unsigned char); + +static void handle_switch(void *data, bool preempt, struct task_struct *p, + struct task_struct *n, unsigned int prev_state) +{ + /* start monitoring only after the first suspension */ + if (prev_state == TASK_INTERRUPTIBLE) + da_handle_start_event_wwnr(p, switch_out_wwnr); + else + da_handle_event_wwnr(p, switch_out_wwnr); + + da_handle_event_wwnr(n, switch_in_wwnr); +} + +static void handle_wakeup(void *data, struct task_struct *p) +{ + da_handle_event_wwnr(p, wakeup_wwnr); +} + +static int enable_wwnr(void) +{ + int retval; + + retval = da_monitor_init_wwnr(); + if (retval) + return retval; + + rv_attach_trace_probe("wwnr", sched_switch, handle_switch); + rv_attach_trace_probe("wwnr", sched_wakeup, handle_wakeup); + + return 0; +} + +static void disable_wwnr(void) +{ + rv_wwnr.enabled = 0; + + rv_detach_trace_probe("wwnr", sched_switch, handle_switch); + rv_detach_trace_probe("wwnr", sched_wakeup, handle_wakeup); + + da_monitor_destroy_wwnr(); +} + +struct rv_monitor rv_wwnr = { + .name = "wwnr", + .description = "wakeup while not running per-task testing model.", + .enable = enable_wwnr, + .disable = disable_wwnr, + .reset = da_monitor_reset_all_wwnr, + .enabled = 0, +}; + +static int register_wwnr(void) +{ + rv_register_monitor(&rv_wwnr); + return 0; +} + +static void unregister_wwnr(void) +{ + rv_unregister_monitor(&rv_wwnr); +} + +module_init(register_wwnr); +module_exit(unregister_wwnr); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Daniel Bristot de Oliveira "); +MODULE_DESCRIPTION("wwnr: wakeup while not running monitor"); diff --git a/kernel/trace/rv/monitors/wwnr/wwnr.h b/kernel/trace/rv/monitors/wwnr/wwnr.h new file mode 100644 index 000000000000..d1afe55cdd4c --- /dev/null +++ b/kernel/trace/rv/monitors/wwnr/wwnr.h @@ -0,0 +1,46 @@ +/* + * Automatically generated C representation of wwnr automaton + * For further information about this format, see kernel documentation: + * Documentation/trace/rv/deterministic_automata.rst + */ + +enum states_wwnr { + not_running_wwnr = 0, + running_wwnr, + state_max_wwnr +}; + +#define INVALID_STATE state_max_wwnr + +enum events_wwnr { + switch_in_wwnr = 0, + switch_out_wwnr, + wakeup_wwnr, + event_max_wwnr +}; + +struct automaton_wwnr { + char *state_names[state_max_wwnr]; + char *event_names[event_max_wwnr]; + unsigned char function[state_max_wwnr][event_max_wwnr]; + unsigned char initial_state; + bool final_states[state_max_wwnr]; +}; + +struct automaton_wwnr automaton_wwnr = { + .state_names = { + "not_running", + "running" + }, + .event_names = { + "switch_in", + "switch_out", + "wakeup" + }, + .function = { + { running_wwnr, INVALID_STATE, not_running_wwnr }, + { INVALID_STATE, not_running_wwnr, INVALID_STATE }, + }, + .initial_state = not_running_wwnr, + .final_states = { 1, 0 }, +}; diff --git a/tools/verification/models/wwnr.dot b/tools/verification/models/wwnr.dot new file mode 100644 index 000000000000..1b206e83129c --- /dev/null +++ b/tools/verification/models/wwnr.dot @@ -0,0 +1,16 @@ +digraph state_automaton { + {node [shape = plaintext, style=invis, label=""] "__init_not_running"}; + {node [shape = ellipse] "not_running"}; + {node [shape = plaintext] "not_running"}; + {node [shape = plaintext] "running"}; + "__init_not_running" -> "not_running"; + "not_running" [label = "not_running", color = green3]; + "not_running" -> "not_running" [ label = "wakeup" ]; + "not_running" -> "running" [ label = "switch_in" ]; + "running" [label = "running"]; + "running" -> "not_running" [ label = "switch_out" ]; + { rank = min ; + "__init_not_running"; + "not_running"; + } +} From patchwork Fri Jul 29 09:38:54 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932256 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 23C2DC19F2B for ; Fri, 29 Jul 2022 09:41:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235946AbiG2JlP (ORCPT ); Fri, 29 Jul 2022 05:41:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235854AbiG2Jkm (ORCPT ); Fri, 29 Jul 2022 05:40:42 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 868BD3A49A; Fri, 29 Jul 2022 02:40:25 -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 ams.source.kernel.org (Postfix) with ESMTPS id DF8A6B826F8; Fri, 29 Jul 2022 09:40:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1F7F7C433D7; Fri, 29 Jul 2022 09:40:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087622; bh=d0PmmR7NTvxxlPC/Xh1Irejd5qUoOBsRQpSFgEY8jyQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JqVsn0SkiJid5Efd+L7dRUNoEK6s6x+s/RfmrgNwbu1lTqpDPP8GSUSz6eY2B6hiX aws9yw+zFIW7lyW+FfRAYUvf+kCN2FUe2Nv/qS+Vbh9k4nbpe33HrtzLzW1wBYKK1T XREZQJO8d4bgkoYHn3mQ9WjG/3UEXtQFA9HQWtNepV1LFFvDh0hFFxIhrZ8gdrkBw2 uw75+vmIDSaODtoM97s6vcgW5wJ3lScYypEXqOx8GCodPQaJl8QY7bbmAlU8jjOClo XWsnmYsjKyZsH/VcDQaoZua0JETIGyHe3GEDYqfHzXc4g06H3v80d8eSeYenxXVVvs fssvRXA+myYug== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 15/16] rv/reactor: Add the printk reactor Date: Fri, 29 Jul 2022 11:38:54 +0200 Message-Id: X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org A reactor that printks the reaction message. Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- kernel/trace/rv/Kconfig | 8 ++++++ kernel/trace/rv/Makefile | 3 ++- kernel/trace/rv/reactor_printk.c | 42 ++++++++++++++++++++++++++++++++ 3 files changed, 52 insertions(+), 1 deletion(-) create mode 100644 kernel/trace/rv/reactor_printk.c diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig index b259d6e8dc7c..e82d5015e6ab 100644 --- a/kernel/trace/rv/Kconfig +++ b/kernel/trace/rv/Kconfig @@ -60,3 +60,11 @@ config RV_REACTORS on the model's execution. By default, the monitors have tracing reactions, printing the monitor output via tracepoints, but other reactions can be added (on-demand) via this interface. + +config RV_REACT_PRINTK + bool "Printk reactor" + depends on RV_REACTORS + default y + help + Enables the printk reactor. The printk reactor emits a printk() + message if an exception is found. diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile index af0ff9a46418..a13c750a35c1 100644 --- a/kernel/trace/rv/Makefile +++ b/kernel/trace/rv/Makefile @@ -1,6 +1,7 @@ # SPDX-License-Identifier: GPL-2.0 obj-$(CONFIG_RV) += rv.o -obj-$(CONFIG_RV_REACTORS) += rv_reactors.o obj-$(CONFIG_RV_MON_WIP) += monitors/wip/wip.o obj-$(CONFIG_RV_MON_WWNR) += monitors/wwnr/wwnr.o +obj-$(CONFIG_RV_REACTORS) += rv_reactors.o +obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o diff --git a/kernel/trace/rv/reactor_printk.c b/kernel/trace/rv/reactor_printk.c new file mode 100644 index 000000000000..31899f953af4 --- /dev/null +++ b/kernel/trace/rv/reactor_printk.c @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira + * + * Printk RV reactor: + * Prints the exception msg to the kernel message log. + */ +#include +#include +#include +#include +#include +#include + +static void rv_printk_reaction(char *msg) +{ + printk_deferred(msg); +} + +static struct rv_reactor rv_printk = { + .name = "printk", + .description = "prints the exception msg to the kernel message log.", + .react = rv_printk_reaction +}; + +static int register_react_printk(void) +{ + rv_register_reactor(&rv_printk); + return 0; +} + +static void unregister_react_printk(void) +{ + rv_unregister_reactor(&rv_printk); +} + +module_init(register_react_printk); +module_exit(unregister_react_printk); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Daniel Bristot de Oliveira"); +MODULE_DESCRIPTION("printk rv reactor: printk if an exception is hit."); From patchwork Fri Jul 29 09:38:55 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 12932258 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 E8F5FC19F2B for ; Fri, 29 Jul 2022 09:41:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235895AbiG2Jlf (ORCPT ); Fri, 29 Jul 2022 05:41:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41330 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235902AbiG2Jk4 (ORCPT ); Fri, 29 Jul 2022 05:40:56 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 579517C1B1; Fri, 29 Jul 2022 02:40:40 -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 ams.source.kernel.org (Postfix) with ESMTPS id 0647BB8270B; Fri, 29 Jul 2022 09:40:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 23480C4347C; Fri, 29 Jul 2022 09:40:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659087627; bh=b8X+BFzH2iCZK+xpE2p+40Q5LRHdNFPjgm8yK8trTBQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QeHeJ8s+6pafXdao7/owo8n9jZhvY4Y9okbI92hUti3u2yunW2LZ30ScOVFilHB2Z 6iFaxa4LYns+Xw0BDf1dypr84xzl+pgETtsfx/wTkL8xe6LuisAWk9SOwgAqBoQEWy i+8NVn0MXePlsPtskbMk+wiicurGzDon9grkLBfvkPF9ElEsaT+X21pDAPXPQTO8Rp CMhL9SiX5tEqXlWw32HpaI8EFnuxDHsHdI+zVwmqfF9DOazMUNrk7LmJ52PuhZt2yv mU85srS0N74786oRq7uSgfLewh9547jiAG+sdfm3kBOdOFE8x/Pqv83AiVAQtjOQ3g sayvBoL5D4QGw== From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , 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-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Subject: [PATCH V9 16/16] rv/reactor: Add the panic reactor Date: Fri, 29 Jul 2022 11:38:55 +0200 Message-Id: <729aae3aba95f35738b8f8180e626d747d1d9da2.1659052063.git.bristot@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Sample reactor that panics the system when an exception is found. This is useful both to capture a vmcore, or to fail-safe a critical system. Cc: Wim Van Sebroeck Cc: Guenter Roeck Cc: Jonathan Corbet Cc: Steven Rostedt 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 --- kernel/trace/rv/Kconfig | 8 ++++++ kernel/trace/rv/Makefile | 1 + kernel/trace/rv/reactor_panic.c | 43 +++++++++++++++++++++++++++++++++ 3 files changed, 52 insertions(+) create mode 100644 kernel/trace/rv/reactor_panic.c diff --git a/kernel/trace/rv/Kconfig b/kernel/trace/rv/Kconfig index e82d5015e6ab..831779607e84 100644 --- a/kernel/trace/rv/Kconfig +++ b/kernel/trace/rv/Kconfig @@ -68,3 +68,11 @@ config RV_REACT_PRINTK help Enables the printk reactor. The printk reactor emits a printk() message if an exception is found. + +config RV_REACT_PANIC + bool "Panic reactor" + depends on RV_REACTORS + default y + help + Enables the panic reactor. The panic reactor emits a printk() + message if an exception is found and panic()s the system. diff --git a/kernel/trace/rv/Makefile b/kernel/trace/rv/Makefile index a13c750a35c1..963d14875b45 100644 --- a/kernel/trace/rv/Makefile +++ b/kernel/trace/rv/Makefile @@ -5,3 +5,4 @@ obj-$(CONFIG_RV_MON_WIP) += monitors/wip/wip.o obj-$(CONFIG_RV_MON_WWNR) += monitors/wwnr/wwnr.o obj-$(CONFIG_RV_REACTORS) += rv_reactors.o obj-$(CONFIG_RV_REACT_PRINTK) += reactor_printk.o +obj-$(CONFIG_RV_REACT_PANIC) += reactor_panic.o diff --git a/kernel/trace/rv/reactor_panic.c b/kernel/trace/rv/reactor_panic.c new file mode 100644 index 000000000000..b698d05dd069 --- /dev/null +++ b/kernel/trace/rv/reactor_panic.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019-2022 Red Hat, Inc. Daniel Bristot de Oliveira + * + * Panic RV reactor: + * Prints the exception msg to the kernel message log and panic(). + */ + +#include +#include +#include +#include +#include +#include + +static void rv_panic_reaction(char *msg) +{ + panic(msg); +} + +static struct rv_reactor rv_panic = { + .name = "panic", + .description = "panic the system if an exception is found.", + .react = rv_panic_reaction +}; + +static int register_react_panic(void) +{ + rv_register_reactor(&rv_panic); + return 0; +} + +static void unregister_react_panic(void) +{ + rv_unregister_reactor(&rv_panic); +} + +module_init(register_react_panic); +module_exit(unregister_react_panic); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Daniel Bristot de Oliveira"); +MODULE_DESCRIPTION("panic rv reactor: panic if an exception is found.");