1 // SPDX-License-Identifier: GPL-2.0
3 * Generic dynamic event control interface
5 * Copyright (C) 2018 Masami Hiramatsu <mhiramat@kernel.org>
8 #include <linux/debugfs.h>
9 #include <linux/kernel.h>
10 #include <linux/list.h>
12 #include <linux/mutex.h>
13 #include <linux/tracefs.h>
16 #include "trace_dynevent.h"
18 static DEFINE_MUTEX(dyn_event_ops_mutex);
19 static LIST_HEAD(dyn_event_ops_list);
21 int dyn_event_register(struct dyn_event_operations *ops)
23 if (!ops || !ops->create || !ops->show || !ops->is_busy ||
24 !ops->free || !ops->match)
27 INIT_LIST_HEAD(&ops->list);
28 mutex_lock(&dyn_event_ops_mutex);
29 list_add_tail(&ops->list, &dyn_event_ops_list);
30 mutex_unlock(&dyn_event_ops_mutex);
34 int dyn_event_release(const char *raw_command, struct dyn_event_operations *type)
36 struct dyn_event *pos, *n;
37 char *system = NULL, *event, *p;
38 int argc, ret = -ENOENT;
41 argv = argv_split(GFP_KERNEL, raw_command, &argc);
45 if (argv[0][0] == '-') {
46 if (argv[0][1] != ':') {
52 event = strchr(argv[0], ':');
60 p = strchr(event, '/');
69 mutex_lock(&event_mutex);
70 for_each_dyn_event_safe(pos, n) {
71 if (type && type != pos->ops)
73 if (!pos->ops->match(system, event,
74 argc - 1, (const char **)argv + 1, pos))
77 ret = pos->ops->free(pos);
81 mutex_unlock(&event_mutex);
87 static int create_dyn_event(const char *raw_command)
89 struct dyn_event_operations *ops;
92 if (raw_command[0] == '-' || raw_command[0] == '!')
93 return dyn_event_release(raw_command, NULL);
95 mutex_lock(&dyn_event_ops_mutex);
96 list_for_each_entry(ops, &dyn_event_ops_list, list) {
97 ret = ops->create(raw_command);
98 if (!ret || ret != -ECANCELED)
101 mutex_unlock(&dyn_event_ops_mutex);
102 if (ret == -ECANCELED)
108 /* Protected by event_mutex */
109 LIST_HEAD(dyn_event_list);
111 void *dyn_event_seq_start(struct seq_file *m, loff_t *pos)
113 mutex_lock(&event_mutex);
114 return seq_list_start(&dyn_event_list, *pos);
117 void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos)
119 return seq_list_next(v, &dyn_event_list, pos);
122 void dyn_event_seq_stop(struct seq_file *m, void *v)
124 mutex_unlock(&event_mutex);
127 static int dyn_event_seq_show(struct seq_file *m, void *v)
129 struct dyn_event *ev = v;
132 return ev->ops->show(m, ev);
137 static const struct seq_operations dyn_event_seq_op = {
138 .start = dyn_event_seq_start,
139 .next = dyn_event_seq_next,
140 .stop = dyn_event_seq_stop,
141 .show = dyn_event_seq_show
145 * dyn_events_release_all - Release all specific events
146 * @type: the dyn_event_operations * which filters releasing events
148 * This releases all events which ->ops matches @type. If @type is NULL,
149 * all events are released.
150 * Return -EBUSY if any of them are in use, and return other errors when
151 * it failed to free the given event. Except for -EBUSY, event releasing
152 * process will be aborted at that point and there may be some other
153 * releasable events on the list.
155 int dyn_events_release_all(struct dyn_event_operations *type)
157 struct dyn_event *ev, *tmp;
160 mutex_lock(&event_mutex);
161 for_each_dyn_event(ev) {
162 if (type && ev->ops != type)
164 if (ev->ops->is_busy(ev)) {
169 for_each_dyn_event_safe(ev, tmp) {
170 if (type && ev->ops != type)
172 ret = ev->ops->free(ev);
177 mutex_unlock(&event_mutex);
182 static int dyn_event_open(struct inode *inode, struct file *file)
186 ret = tracing_check_open_get_tr(NULL);
190 if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
191 ret = dyn_events_release_all(NULL);
196 return seq_open(file, &dyn_event_seq_op);
199 static ssize_t dyn_event_write(struct file *file, const char __user *buffer,
200 size_t count, loff_t *ppos)
202 return trace_parse_run_command(file, buffer, count, ppos,
206 static const struct file_operations dynamic_events_ops = {
207 .owner = THIS_MODULE,
208 .open = dyn_event_open,
211 .release = seq_release,
212 .write = dyn_event_write,
215 /* Make a tracefs interface for controlling dynamic events */
216 static __init int init_dynamic_event(void)
218 struct dentry *entry;
221 ret = tracing_init_dentry();
225 entry = tracefs_create_file("dynamic_events", 0644, NULL,
226 NULL, &dynamic_events_ops);
228 /* Event list interface */
230 pr_warn("Could not create tracefs 'dynamic_events' entry\n");
234 fs_initcall(init_dynamic_event);
237 * dynevent_arg_add - Add an arg to a dynevent_cmd
238 * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
239 * @arg: The argument to append to the current cmd
240 * @check_arg: An (optional) pointer to a function checking arg sanity
242 * Append an argument to a dynevent_cmd. The argument string will be
243 * appended to the current cmd string, followed by a separator, if
244 * applicable. Before the argument is added, the @check_arg function,
245 * if present, will be used to check the sanity of the current arg
248 * The cmd string and separator should be set using the
249 * dynevent_arg_init() before any arguments are added using this
252 * Return: 0 if successful, error otherwise.
254 int dynevent_arg_add(struct dynevent_cmd *cmd,
255 struct dynevent_arg *arg,
256 dynevent_check_arg_fn_t check_arg)
261 ret = check_arg(arg);
266 ret = seq_buf_printf(&cmd->seq, " %s%c", arg->str, arg->separator);
268 pr_err("String is too long: %s%c\n", arg->str, arg->separator);
276 * dynevent_arg_pair_add - Add an arg pair to a dynevent_cmd
277 * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
278 * @arg_pair: The argument pair to append to the current cmd
279 * @check_arg: An (optional) pointer to a function checking arg sanity
281 * Append an argument pair to a dynevent_cmd. An argument pair
282 * consists of a left-hand-side argument and a right-hand-side
283 * argument separated by an operator, which can be whitespace, all
284 * followed by a separator, if applicable. This can be used to add
285 * arguments of the form 'type variable_name;' or 'x+y'.
287 * The lhs argument string will be appended to the current cmd string,
288 * followed by an operator, if applicable, followed by the rhs string,
289 * followed finally by a separator, if applicable. Before the
290 * argument is added, the @check_arg function, if present, will be
291 * used to check the sanity of the current arg strings.
293 * The cmd strings, operator, and separator should be set using the
294 * dynevent_arg_pair_init() before any arguments are added using this
297 * Return: 0 if successful, error otherwise.
299 int dynevent_arg_pair_add(struct dynevent_cmd *cmd,
300 struct dynevent_arg_pair *arg_pair,
301 dynevent_check_arg_fn_t check_arg)
306 ret = check_arg(arg_pair);
311 ret = seq_buf_printf(&cmd->seq, " %s%c%s%c", arg_pair->lhs,
312 arg_pair->operator, arg_pair->rhs,
313 arg_pair->separator);
315 pr_err("field string is too long: %s%c%s%c\n", arg_pair->lhs,
316 arg_pair->operator, arg_pair->rhs,
317 arg_pair->separator);
325 * dynevent_str_add - Add a string to a dynevent_cmd
326 * @cmd: A pointer to the dynevent_cmd struct representing the new event cmd
327 * @str: The string to append to the current cmd
329 * Append a string to a dynevent_cmd. The string will be appended to
330 * the current cmd string as-is, with nothing prepended or appended.
332 * Return: 0 if successful, error otherwise.
334 int dynevent_str_add(struct dynevent_cmd *cmd, const char *str)
338 ret = seq_buf_puts(&cmd->seq, str);
340 pr_err("String is too long: %s\n", str);
348 * dynevent_cmd_init - Initialize a dynevent_cmd object
349 * @cmd: A pointer to the dynevent_cmd struct representing the cmd
350 * @buf: A pointer to the buffer to generate the command into
351 * @maxlen: The length of the buffer the command will be generated into
352 * @type: The type of the cmd, checked against further operations
353 * @run_command: The type-specific function that will actually run the command
355 * Initialize a dynevent_cmd. A dynevent_cmd is used to build up and
356 * run dynamic event creation commands, such as commands for creating
357 * synthetic and kprobe events. Before calling any of the functions
358 * used to build the command, a dynevent_cmd object should be
359 * instantiated and initialized using this function.
361 * The initialization sets things up by saving a pointer to the
362 * user-supplied buffer and its length via the @buf and @maxlen
363 * params, and by saving the cmd-specific @type and @run_command
364 * params which are used to check subsequent dynevent_cmd operations
365 * and actually run the command when complete.
367 void dynevent_cmd_init(struct dynevent_cmd *cmd, char *buf, int maxlen,
368 enum dynevent_type type,
369 dynevent_create_fn_t run_command)
371 memset(cmd, '\0', sizeof(*cmd));
373 seq_buf_init(&cmd->seq, buf, maxlen);
375 cmd->run_command = run_command;
379 * dynevent_arg_init - Initialize a dynevent_arg object
380 * @arg: A pointer to the dynevent_arg struct representing the arg
381 * @separator: An (optional) separator, appended after adding the arg
383 * Initialize a dynevent_arg object. A dynevent_arg represents an
384 * object used to append single arguments to the current command
385 * string. After the arg string is successfully appended to the
386 * command string, the optional @separator is appended. If no
387 * separator was specified when initializing the arg, a space will be
390 void dynevent_arg_init(struct dynevent_arg *arg,
393 memset(arg, '\0', sizeof(*arg));
397 arg->separator = separator;
401 * dynevent_arg_pair_init - Initialize a dynevent_arg_pair object
402 * @arg_pair: A pointer to the dynevent_arg_pair struct representing the arg
403 * @operator: An (optional) operator, appended after adding the first arg
404 * @separator: An (optional) separator, appended after adding the second arg
406 * Initialize a dynevent_arg_pair object. A dynevent_arg_pair
407 * represents an object used to append argument pairs such as 'type
408 * variable_name;' or 'x+y' to the current command string. An
409 * argument pair consists of a left-hand-side argument and a
410 * right-hand-side argument separated by an operator, which can be
411 * whitespace, all followed by a separator, if applicable. After the
412 * first arg string is successfully appended to the command string,
413 * the optional @operator is appended, followed by the second arg and
414 * optional @separator. If no separator was specified when
415 * initializing the arg, a space will be appended.
417 void dynevent_arg_pair_init(struct dynevent_arg_pair *arg_pair,
418 char operator, char separator)
420 memset(arg_pair, '\0', sizeof(*arg_pair));
424 arg_pair->operator = operator;
428 arg_pair->separator = separator;
432 * dynevent_create - Create the dynamic event contained in dynevent_cmd
433 * @cmd: The dynevent_cmd object containing the dynamic event creation command
435 * Once a dynevent_cmd object has been successfully built up via the
436 * dynevent_cmd_init(), dynevent_arg_add() and dynevent_arg_pair_add()
437 * functions, this function runs the final command to actually create
440 * Return: 0 if the event was successfully created, error otherwise.
442 int dynevent_create(struct dynevent_cmd *cmd)
444 return cmd->run_command(cmd);
446 EXPORT_SYMBOL_GPL(dynevent_create);