// SPDX-License-Identifier: GPL-2.0
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/*
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* Generic dynamic event control interface
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*
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* Copyright (C) 2018 Masami Hiramatsu <mhiramat@kernel.org>
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*/
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#include <linux/debugfs.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/mm.h>
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#include <linux/mutex.h>
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#include <linux/tracefs.h>
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#include "trace.h"
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#include "trace_dynevent.h"
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static DEFINE_MUTEX(dyn_event_ops_mutex);
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static LIST_HEAD(dyn_event_ops_list);
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int dyn_event_register(struct dyn_event_operations *ops)
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{
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if (!ops || !ops->create || !ops->show || !ops->is_busy ||
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!ops->free || !ops->match)
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return -EINVAL;
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INIT_LIST_HEAD(&ops->list);
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mutex_lock(&dyn_event_ops_mutex);
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list_add_tail(&ops->list, &dyn_event_ops_list);
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mutex_unlock(&dyn_event_ops_mutex);
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return 0;
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}
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int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type)
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{
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struct dyn_event *pos, *n;
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char *system = NULL, *event, *p;
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int ret = -ENOENT;
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if (argv[0][0] == '-') {
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if (argv[0][1] != ':')
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return -EINVAL;
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event = &argv[0][2];
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} else {
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event = strchr(argv[0], ':');
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if (!event)
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return -EINVAL;
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event++;
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}
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argc--; argv++;
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p = strchr(event, '/');
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if (p) {
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system = event;
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event = p + 1;
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*p = '\0';
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}
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if (event[0] == '\0')
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return -EINVAL;
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mutex_lock(&event_mutex);
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for_each_dyn_event_safe(pos, n) {
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if (type && type != pos->ops)
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continue;
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if (!pos->ops->match(system, event,
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argc, (const char **)argv, pos))
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continue;
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ret = pos->ops->free(pos);
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if (ret)
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break;
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}
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tracing_reset_all_online_cpus();
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mutex_unlock(&event_mutex);
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return ret;
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}
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static int create_dyn_event(int argc, char **argv)
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{
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struct dyn_event_operations *ops;
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int ret = -ENODEV;
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if (argv[0][0] == '-' || argv[0][0] == '!')
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return dyn_event_release(argc, argv, NULL);
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mutex_lock(&dyn_event_ops_mutex);
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list_for_each_entry(ops, &dyn_event_ops_list, list) {
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ret = ops->create(argc, (const char **)argv);
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if (!ret || ret != -ECANCELED)
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break;
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}
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mutex_unlock(&dyn_event_ops_mutex);
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if (ret == -ECANCELED)
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ret = -EINVAL;
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return ret;
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}
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/* Protected by event_mutex */
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LIST_HEAD(dyn_event_list);
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void *dyn_event_seq_start(struct seq_file *m, loff_t *pos)
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{
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mutex_lock(&event_mutex);
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return seq_list_start(&dyn_event_list, *pos);
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}
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void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos)
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{
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return seq_list_next(v, &dyn_event_list, pos);
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}
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void dyn_event_seq_stop(struct seq_file *m, void *v)
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{
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mutex_unlock(&event_mutex);
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}
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static int dyn_event_seq_show(struct seq_file *m, void *v)
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{
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struct dyn_event *ev = v;
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if (ev && ev->ops)
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return ev->ops->show(m, ev);
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return 0;
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}
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static const struct seq_operations dyn_event_seq_op = {
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.start = dyn_event_seq_start,
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.next = dyn_event_seq_next,
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.stop = dyn_event_seq_stop,
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.show = dyn_event_seq_show
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};
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/*
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* dyn_events_release_all - Release all specific events
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* @type: the dyn_event_operations * which filters releasing events
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*
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* This releases all events which ->ops matches @type. If @type is NULL,
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* all events are released.
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* Return -EBUSY if any of them are in use, and return other errors when
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* it failed to free the given event. Except for -EBUSY, event releasing
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* process will be aborted at that point and there may be some other
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* releasable events on the list.
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*/
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int dyn_events_release_all(struct dyn_event_operations *type)
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{
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struct dyn_event *ev, *tmp;
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int ret = 0;
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mutex_lock(&event_mutex);
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for_each_dyn_event(ev) {
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if (type && ev->ops != type)
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continue;
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if (ev->ops->is_busy(ev)) {
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ret = -EBUSY;
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goto out;
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}
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}
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for_each_dyn_event_safe(ev, tmp) {
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if (type && ev->ops != type)
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continue;
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ret = ev->ops->free(ev);
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if (ret)
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break;
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}
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out:
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tracing_reset_all_online_cpus();
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mutex_unlock(&event_mutex);
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return ret;
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}
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static int dyn_event_open(struct inode *inode, struct file *file)
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{
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int ret;
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ret = tracing_check_open_get_tr(NULL);
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if (ret)
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return ret;
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if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
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ret = dyn_events_release_all(NULL);
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if (ret < 0)
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return ret;
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}
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return seq_open(file, &dyn_event_seq_op);
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}
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static ssize_t dyn_event_write(struct file *file, const char __user *buffer,
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size_t count, loff_t *ppos)
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{
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return trace_parse_run_command(file, buffer, count, ppos,
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create_dyn_event);
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}
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static const struct file_operations dynamic_events_ops = {
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.owner = THIS_MODULE,
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.open = dyn_event_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = seq_release,
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.write = dyn_event_write,
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};
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/* Make a tracefs interface for controlling dynamic events */
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static __init int init_dynamic_event(void)
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{
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struct dentry *entry;
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int ret;
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ret = tracing_init_dentry();
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if (ret)
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return 0;
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entry = tracefs_create_file("dynamic_events", 0644, NULL,
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NULL, &dynamic_events_ops);
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/* Event list interface */
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if (!entry)
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pr_warn("Could not create tracefs 'dynamic_events' entry\n");
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return 0;
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}
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fs_initcall(init_dynamic_event);
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/**
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* dynevent_arg_add - Add an arg to a dynevent_cmd
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* @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
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* @arg: The argument to append to the current cmd
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* @check_arg: An (optional) pointer to a function checking arg sanity
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*
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* Append an argument to a dynevent_cmd. The argument string will be
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* appended to the current cmd string, followed by a separator, if
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* applicable. Before the argument is added, the @check_arg function,
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* if present, will be used to check the sanity of the current arg
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* string.
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*
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* The cmd string and separator should be set using the
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* dynevent_arg_init() before any arguments are added using this
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* function.
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*
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* Return: 0 if successful, error otherwise.
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*/
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int dynevent_arg_add(struct dynevent_cmd *cmd,
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struct dynevent_arg *arg,
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dynevent_check_arg_fn_t check_arg)
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{
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int ret = 0;
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if (check_arg) {
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ret = check_arg(arg);
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if (ret)
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return ret;
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}
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ret = seq_buf_printf(&cmd->seq, " %s%c", arg->str, arg->separator);
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if (ret) {
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pr_err("String is too long: %s%c\n", arg->str, arg->separator);
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return -E2BIG;
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}
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return ret;
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}
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/**
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* dynevent_arg_pair_add - Add an arg pair to a dynevent_cmd
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* @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
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* @arg_pair: The argument pair to append to the current cmd
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* @check_arg: An (optional) pointer to a function checking arg sanity
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*
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* Append an argument pair to a dynevent_cmd. An argument pair
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* consists of a left-hand-side argument and a right-hand-side
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* argument separated by an operator, which can be whitespace, all
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* followed by a separator, if applicable. This can be used to add
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* arguments of the form 'type variable_name;' or 'x+y'.
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*
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* The lhs argument string will be appended to the current cmd string,
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* followed by an operator, if applicable, followd by the rhs string,
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* followed finally by a separator, if applicable. Before the
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* argument is added, the @check_arg function, if present, will be
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* used to check the sanity of the current arg strings.
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*
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* The cmd strings, operator, and separator should be set using the
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* dynevent_arg_pair_init() before any arguments are added using this
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* function.
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*
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* Return: 0 if successful, error otherwise.
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*/
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int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
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struct dynevent_arg_pair *arg_pair,
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dynevent_check_arg_fn_t check_arg)
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{
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int ret = 0;
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if (check_arg) {
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ret = check_arg(arg_pair);
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if (ret)
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return ret;
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}
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ret = seq_buf_printf(&cmd->seq, " %s%c%s%c", arg_pair->lhs,
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arg_pair->operator, arg_pair->rhs,
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arg_pair->separator);
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if (ret) {
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pr_err("field string is too long: %s%c%s%c\n", arg_pair->lhs,
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arg_pair->operator, arg_pair->rhs,
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arg_pair->separator);
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return -E2BIG;
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}
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return ret;
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}
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/**
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* dynevent_str_add - Add a string to a dynevent_cmd
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* @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
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* @str: The string to append to the current cmd
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*
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* Append a string to a dynevent_cmd. The string will be appended to
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* the current cmd string as-is, with nothing prepended or appended.
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*
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* Return: 0 if successful, error otherwise.
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*/
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int dynevent_str_add(struct dynevent_cmd *cmd, const char *str)
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{
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int ret = 0;
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ret = seq_buf_puts(&cmd->seq, str);
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if (ret) {
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pr_err("String is too long: %s\n", str);
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return -E2BIG;
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}
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return ret;
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}
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/**
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* dynevent_cmd_init - Initialize a dynevent_cmd object
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* @cmd: A pointer to the dynevent_cmd struct representing the cmd
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* @buf: A pointer to the buffer to generate the command into
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* @maxlen: The length of the buffer the command will be generated into
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* @type: The type of the cmd, checked against further operations
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* @run_command: The type-specific function that will actually run the command
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*
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* Initialize a dynevent_cmd. A dynevent_cmd is used to build up and
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* run dynamic event creation commands, such as commands for creating
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* synthetic and kprobe events. Before calling any of the functions
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* used to build the command, a dynevent_cmd object should be
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* instantiated and initialized using this function.
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*
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* The initialization sets things up by saving a pointer to the
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* user-supplied buffer and its length via the @buf and @maxlen
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* params, and by saving the cmd-specific @type and @run_command
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* params which are used to check subsequent dynevent_cmd operations
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* and actually run the command when complete.
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*/
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void dynevent_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen,
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enum dynevent_type type,
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dynevent_create_fn_t run_command)
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{
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memset(cmd, '\0', sizeof(*cmd));
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seq_buf_init(&cmd->seq, buf, maxlen);
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cmd->type = type;
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cmd->run_command = run_command;
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}
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/**
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* dynevent_arg_init - Initialize a dynevent_arg object
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* @arg: A pointer to the dynevent_arg struct representing the arg
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* @separator: An (optional) separator, appended after adding the arg
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*
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* Initialize a dynevent_arg object. A dynevent_arg represents an
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* object used to append single arguments to the current command
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* string. After the arg string is successfully appended to the
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* command string, the optional @separator is appended. If no
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* separator was specified when initializing the arg, a space will be
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* appended.
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*/
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void dynevent_arg_init(struct dynevent_arg *arg,
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char separator)
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{
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memset(arg, '\0', sizeof(*arg));
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if (!separator)
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separator = ' ';
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arg->separator = separator;
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}
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/**
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* dynevent_arg_pair_init - Initialize a dynevent_arg_pair object
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* @arg_pair: A pointer to the dynevent_arg_pair struct representing the arg
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* @operator: An (optional) operator, appended after adding the first arg
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* @separator: An (optional) separator, appended after adding the second arg
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*
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* Initialize a dynevent_arg_pair object. A dynevent_arg_pair
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* represents an object used to append argument pairs such as 'type
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* variable_name;' or 'x+y' to the current command string. An
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* argument pair consists of a left-hand-side argument and a
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* right-hand-side argument separated by an operator, which can be
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* whitespace, all followed by a separator, if applicable. After the
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* first arg string is successfully appended to the command string,
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* the optional @operator is appended, followed by the second arg and
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* optional @separator. If no separator was specified when
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* initializing the arg, a space will be appended.
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*/
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void dynevent_arg_pair_init(struct dynevent_arg_pair *arg_pair,
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char operator, char separator)
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{
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memset(arg_pair, '\0', sizeof(*arg_pair));
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if (!operator)
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operator = ' ';
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arg_pair->operator = operator;
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if (!separator)
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separator = ' ';
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arg_pair->separator = separator;
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}
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/**
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* dynevent_create - Create the dynamic event contained in dynevent_cmd
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* @cmd: The dynevent_cmd object containing the dynamic event creation command
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*
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* Once a dynevent_cmd object has been successfully built up via the
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* dynevent_cmd_init(), dynevent_arg_add() and dynevent_arg_pair_add()
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* functions, this function runs the final command to actually create
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* the event.
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*
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* Return: 0 if the event was successfully created, error otherwise.
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*/
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int dynevent_create(struct dynevent_cmd *cmd)
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{
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return cmd->run_command(cmd);
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}
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EXPORT_SYMBOL_GPL(dynevent_create);
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