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