// 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_dynevent.h"
static DEFINE_MUTEX(dyn_event_ops_mutex);
static LIST_HEAD(dyn_event_ops_list);
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(int argc, char **argv, struct dyn_event_operations *type)
{
struct dyn_event *pos, *n;
char *system = NULL, *event, *p;
int ret = -ENOENT;
if (argv[0][0] == '-') {
if (argv[0][1] != ':')
return -EINVAL;
event = &argv[0][2];
} else {
event = strchr(argv[0], ':');
if (!event)
return -EINVAL;
event++;
}
argc--; argv++;
p = strchr(event, '/');
if (p) {
system = event;
event = p + 1;
*p = '\0';
}
if (event[0] == '\0')
return -EINVAL;
mutex_lock(&event_mutex);
for_each_dyn_event_safe(pos, n) {
if (type && type != pos->ops)
continue;
if (!pos->ops->match(system, event,
argc, (const char **)argv, pos))
continue;
ret = pos->ops->free(pos);
if (ret)
break;
}
mutex_unlock(&event_mutex);
return ret;
}
static int create_dyn_event(int argc, char **argv)
{
struct dyn_event_operations *ops;
int ret = -ENODEV;
if (argv[0][0] == '-' || argv[0][0] == '!')
return dyn_event_release(argc, argv, NULL);
mutex_lock(&dyn_event_ops_mutex);
list_for_each_entry(ops, &dyn_event_ops_list, list) {
ret = ops->create(argc, (const char **)argv);
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:
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)
{
struct dentry *d_tracer;
struct dentry *entry;
d_tracer = tracing_init_dentry();
if (IS_ERR(d_tracer))
return 0;
entry = tracefs_create_file("dynamic_events", 0644, d_tracer,
NULL, &dynamic_events_ops);
/* Event list interface */
if (!entry)
pr_warn("Could not create tracefs 'dynamic_events' entry\n");
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, followd 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
* 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);
