Commit 5448d44c authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt (VMware)

tracing: Add unified dynamic event framework

Add unified dynamic event framework for ftrace kprobes, uprobes
and synthetic events. Those dynamic events can be co-exist on
same file because those syntax doesn't overlap.

This introduces a framework part which provides a unified tracefs
interface and operations.

Link: http://lkml.kernel.org/r/154140852824.17322.12250362185969352095.stgit@devboxReviewed-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: default avatarTom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent d00bbea9
......@@ -518,6 +518,9 @@ config BPF_EVENTS
help
This allows the user to attach BPF programs to kprobe events.
config DYNAMIC_EVENTS
def_bool n
config PROBE_EVENTS
def_bool n
......
......@@ -79,6 +79,7 @@ endif
ifeq ($(CONFIG_TRACING),y)
obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
endif
obj-$(CONFIG_DYNAMIC_EVENTS) += trace_dynevent.o
obj-$(CONFIG_PROBE_EVENTS) += trace_probe.o
obj-$(CONFIG_UPROBE_EVENTS) += trace_uprobe.o
......
......@@ -4604,6 +4604,10 @@ static const char readme_msg[] =
"\t\t\t traces\n"
#endif
#endif /* CONFIG_STACK_TRACER */
#ifdef CONFIG_DYNAMIC_EVENTS
" dynamic_events\t\t- Add/remove/show the generic dynamic events\n"
"\t\t\t Write into this file to define/undefine new trace events.\n"
#endif
#ifdef CONFIG_KPROBE_EVENTS
" kprobe_events\t\t- Add/remove/show the kernel dynamic events\n"
"\t\t\t Write into this file to define/undefine new trace events.\n"
......
// 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][1] != ':')
return -EINVAL;
event = &argv[0][2];
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, pos)) {
ret = pos->ops->free(pos);
break;
}
}
mutex_unlock(&event_mutex);
return ret;
}
static int create_dyn_event(int argc, char **argv)
{
struct dyn_event_operations *ops;
int ret;
if (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;
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);
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Common header file for generic dynamic events.
*/
#ifndef _TRACE_DYNEVENT_H
#define _TRACE_DYNEVENT_H
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/seq_file.h>
#include "trace.h"
struct dyn_event;
/**
* struct dyn_event_operations - Methods for each type of dynamic events
*
* These methods must be set for each type, since there is no default method.
* Before using this for dyn_event_init(), it must be registered by
* dyn_event_register().
*
* @create: Parse and create event method. This is invoked when user passes
* a event definition to dynamic_events interface. This must not destruct
* the arguments and return -ECANCELED if given arguments doesn't match its
* command prefix.
* @show: Showing method. This is invoked when user reads the event definitions
* via dynamic_events interface.
* @is_busy: Check whether given event is busy so that it can not be deleted.
* Return true if it is busy, otherwides false.
* @free: Delete the given event. Return 0 if success, otherwides error.
* @match: Check whether given event and system name match this event.
* Return true if it matches, otherwides false.
*
* Except for @create, these methods are called under holding event_mutex.
*/
struct dyn_event_operations {
struct list_head list;
int (*create)(int argc, const char *argv[]);
int (*show)(struct seq_file *m, struct dyn_event *ev);
bool (*is_busy)(struct dyn_event *ev);
int (*free)(struct dyn_event *ev);
bool (*match)(const char *system, const char *event,
struct dyn_event *ev);
};
/* Register new dyn_event type -- must be called at first */
int dyn_event_register(struct dyn_event_operations *ops);
/**
* struct dyn_event - Dynamic event list header
*
* The dyn_event structure encapsulates a list and a pointer to the operators
* for making a global list of dynamic events.
* User must includes this in each event structure, so that those events can
* be added/removed via dynamic_events interface.
*/
struct dyn_event {
struct list_head list;
struct dyn_event_operations *ops;
};
extern struct list_head dyn_event_list;
static inline
int dyn_event_init(struct dyn_event *ev, struct dyn_event_operations *ops)
{
if (!ev || !ops)
return -EINVAL;
INIT_LIST_HEAD(&ev->list);
ev->ops = ops;
return 0;
}
static inline int dyn_event_add(struct dyn_event *ev)
{
lockdep_assert_held(&event_mutex);
if (!ev || !ev->ops)
return -EINVAL;
list_add_tail(&ev->list, &dyn_event_list);
return 0;
}
static inline void dyn_event_remove(struct dyn_event *ev)
{
lockdep_assert_held(&event_mutex);
list_del_init(&ev->list);
}
void *dyn_event_seq_start(struct seq_file *m, loff_t *pos);
void *dyn_event_seq_next(struct seq_file *m, void *v, loff_t *pos);
void dyn_event_seq_stop(struct seq_file *m, void *v);
int dyn_events_release_all(struct dyn_event_operations *type);
int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type);
/*
* for_each_dyn_event - iterate over the dyn_event list
* @pos: the struct dyn_event * to use as a loop cursor
*
* This is just a basement of for_each macro. Wrap this for
* each actual event structure with ops filtering.
*/
#define for_each_dyn_event(pos) \
list_for_each_entry(pos, &dyn_event_list, list)
/*
* for_each_dyn_event - iterate over the dyn_event list safely
* @pos: the struct dyn_event * to use as a loop cursor
* @n: the struct dyn_event * to use as temporary storage
*/
#define for_each_dyn_event_safe(pos, n) \
list_for_each_entry_safe(pos, n, &dyn_event_list, list)
#endif
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