Linux 4.1.18

[linux/fpc-iii.git] / kernel / trace / trace_events.c

/*
 * event tracer
 *
 * Copyright (C) 2008 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
 *
 *  - Added format output of fields of the trace point.
 *    This was based off of work by Tom Zanussi <tzanussi@gmail.com>.
 *
 */

#define pr_fmt(fmt) fmt

#include <linux/workqueue.h>
#include <linux/spinlock.h>
#include <linux/kthread.h>
#include <linux/tracefs.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/slab.h>
#include <linux/delay.h>

#include <asm/setup.h>

#include "trace_output.h"

#undef TRACE_SYSTEM
#define TRACE_SYSTEM "TRACE_SYSTEM"

DEFINE_MUTEX(event_mutex);

LIST_HEAD(ftrace_events);
static LIST_HEAD(ftrace_common_fields);

#define GFP_TRACE (GFP_KERNEL | __GFP_ZERO)

static struct kmem_cache *field_cachep;
static struct kmem_cache *file_cachep;

#define SYSTEM_FL_FREE_NAME             (1 << 31)

static inline int system_refcount(struct event_subsystem *system)
{
        return system->ref_count & ~SYSTEM_FL_FREE_NAME;
}

static int system_refcount_inc(struct event_subsystem *system)
{
        return (system->ref_count++) & ~SYSTEM_FL_FREE_NAME;
}

static int system_refcount_dec(struct event_subsystem *system)
{
        return (--system->ref_count) & ~SYSTEM_FL_FREE_NAME;
}

/* Double loops, do not use break, only goto's work */
#define do_for_each_event_file(tr, file)                        \
        list_for_each_entry(tr, &ftrace_trace_arrays, list) {   \
                list_for_each_entry(file, &tr->events, list)

#define do_for_each_event_file_safe(tr, file)                   \
        list_for_each_entry(tr, &ftrace_trace_arrays, list) {   \
                struct ftrace_event_file *___n;                         \
                list_for_each_entry_safe(file, ___n, &tr->events, list)

#define while_for_each_event_file()             \
        }

static struct list_head *
trace_get_fields(struct ftrace_event_call *event_call)
{
        if (!event_call->class->get_fields)
                return &event_call->class->fields;
        return event_call->class->get_fields(event_call);
}

static struct ftrace_event_field *
__find_event_field(struct list_head *head, char *name)
{
        struct ftrace_event_field *field;

        list_for_each_entry(field, head, link) {
                if (!strcmp(field->name, name))
                        return field;
        }

        return NULL;
}

struct ftrace_event_field *
trace_find_event_field(struct ftrace_event_call *call, char *name)
{
        struct ftrace_event_field *field;
        struct list_head *head;

        field = __find_event_field(&ftrace_common_fields, name);
        if (field)
                return field;

        head = trace_get_fields(call);
        return __find_event_field(head, name);
}

static int __trace_define_field(struct list_head *head, const char *type,
                                const char *name, int offset, int size,
                                int is_signed, int filter_type)
{
        struct ftrace_event_field *field;

        field = kmem_cache_alloc(field_cachep, GFP_TRACE);
        if (!field)
                return -ENOMEM;

        field->name = name;
        field->type = type;

        if (filter_type == FILTER_OTHER)
                field->filter_type = filter_assign_type(type);
        else
                field->filter_type = filter_type;

        field->offset = offset;
        field->size = size;
        field->is_signed = is_signed;

        list_add(&field->link, head);

        return 0;
}

int trace_define_field(struct ftrace_event_call *call, const char *type,
                       const char *name, int offset, int size, int is_signed,
                       int filter_type)
{
        struct list_head *head;

        if (WARN_ON(!call->class))
                return 0;

        head = trace_get_fields(call);
        return __trace_define_field(head, type, name, offset, size,
                                    is_signed, filter_type);
}
EXPORT_SYMBOL_GPL(trace_define_field);

#define __common_field(type, item)                                      \
        ret = __trace_define_field(&ftrace_common_fields, #type,        \
                                   "common_" #item,                     \
                                   offsetof(typeof(ent), item),         \
                                   sizeof(ent.item),                    \
                                   is_signed_type(type), FILTER_OTHER); \
        if (ret)                                                        \
                return ret;

static int trace_define_common_fields(void)
{
        int ret;
        struct trace_entry ent;

        __common_field(unsigned short, type);
        __common_field(unsigned char, flags);
        __common_field(unsigned char, preempt_count);
        __common_field(int, pid);

        return ret;
}

static void trace_destroy_fields(struct ftrace_event_call *call)
{
        struct ftrace_event_field *field, *next;
        struct list_head *head;

        head = trace_get_fields(call);
        list_for_each_entry_safe(field, next, head, link) {
                list_del(&field->link);
                kmem_cache_free(field_cachep, field);
        }
}

int trace_event_raw_init(struct ftrace_event_call *call)
{
        int id;

        id = register_ftrace_event(&call->event);
        if (!id)
                return -ENODEV;

        return 0;
}
EXPORT_SYMBOL_GPL(trace_event_raw_init);

void *ftrace_event_buffer_reserve(struct ftrace_event_buffer *fbuffer,
                                  struct ftrace_event_file *ftrace_file,
                                  unsigned long len)
{
        struct ftrace_event_call *event_call = ftrace_file->event_call;

        local_save_flags(fbuffer->flags);
        fbuffer->pc = preempt_count();
        fbuffer->ftrace_file = ftrace_file;

        fbuffer->event =
                trace_event_buffer_lock_reserve(&fbuffer->buffer, ftrace_file,
                                                event_call->event.type, len,
                                                fbuffer->flags, fbuffer->pc);
        if (!fbuffer->event)
                return NULL;

        fbuffer->entry = ring_buffer_event_data(fbuffer->event);
        return fbuffer->entry;
}
EXPORT_SYMBOL_GPL(ftrace_event_buffer_reserve);

static DEFINE_SPINLOCK(tracepoint_iter_lock);

static void output_printk(struct ftrace_event_buffer *fbuffer)
{
        struct ftrace_event_call *event_call;
        struct trace_event *event;
        unsigned long flags;
        struct trace_iterator *iter = tracepoint_print_iter;

        if (!iter)
                return;

        event_call = fbuffer->ftrace_file->event_call;
        if (!event_call || !event_call->event.funcs ||
            !event_call->event.funcs->trace)
                return;

        event = &fbuffer->ftrace_file->event_call->event;

        spin_lock_irqsave(&tracepoint_iter_lock, flags);
        trace_seq_init(&iter->seq);
        iter->ent = fbuffer->entry;
        event_call->event.funcs->trace(iter, 0, event);
        trace_seq_putc(&iter->seq, 0);
        printk("%s", iter->seq.buffer);

        spin_unlock_irqrestore(&tracepoint_iter_lock, flags);
}

void ftrace_event_buffer_commit(struct ftrace_event_buffer *fbuffer)
{
        if (tracepoint_printk)
                output_printk(fbuffer);

        event_trigger_unlock_commit(fbuffer->ftrace_file, fbuffer->buffer,
                                    fbuffer->event, fbuffer->entry,
                                    fbuffer->flags, fbuffer->pc);
}
EXPORT_SYMBOL_GPL(ftrace_event_buffer_commit);

int ftrace_event_reg(struct ftrace_event_call *call,
                     enum trace_reg type, void *data)
{
        struct ftrace_event_file *file = data;

        WARN_ON(!(call->flags & TRACE_EVENT_FL_TRACEPOINT));
        switch (type) {
        case TRACE_REG_REGISTER:
                return tracepoint_probe_register(call->tp,
                                                 call->class->probe,
                                                 file);
        case TRACE_REG_UNREGISTER:
                tracepoint_probe_unregister(call->tp,
                                            call->class->probe,
                                            file);
                return 0;

#ifdef CONFIG_PERF_EVENTS
        case TRACE_REG_PERF_REGISTER:
                return tracepoint_probe_register(call->tp,
                                                 call->class->perf_probe,
                                                 call);
        case TRACE_REG_PERF_UNREGISTER:
                tracepoint_probe_unregister(call->tp,
                                            call->class->perf_probe,
                                            call);
                return 0;
        case TRACE_REG_PERF_OPEN:
        case TRACE_REG_PERF_CLOSE:
        case TRACE_REG_PERF_ADD:
        case TRACE_REG_PERF_DEL:
                return 0;
#endif
        }
        return 0;
}
EXPORT_SYMBOL_GPL(ftrace_event_reg);

void trace_event_enable_cmd_record(bool enable)
{
        struct ftrace_event_file *file;
        struct trace_array *tr;

        mutex_lock(&event_mutex);
        do_for_each_event_file(tr, file) {

                if (!(file->flags & FTRACE_EVENT_FL_ENABLED))
                        continue;

                if (enable) {
                        tracing_start_cmdline_record();
                        set_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags);
                } else {
                        tracing_stop_cmdline_record();
                        clear_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags);
                }
        } while_for_each_event_file();
        mutex_unlock(&event_mutex);
}

static int __ftrace_event_enable_disable(struct ftrace_event_file *file,
                                         int enable, int soft_disable)
{
        struct ftrace_event_call *call = file->event_call;
        int ret = 0;
        int disable;

        switch (enable) {
        case 0:
                /*
                 * When soft_disable is set and enable is cleared, the sm_ref
                 * reference counter is decremented. If it reaches 0, we want
                 * to clear the SOFT_DISABLED flag but leave the event in the
                 * state that it was. That is, if the event was enabled and
                 * SOFT_DISABLED isn't set, then do nothing. But if SOFT_DISABLED
                 * is set we do not want the event to be enabled before we
                 * clear the bit.
                 *
                 * When soft_disable is not set but the SOFT_MODE flag is,
                 * we do nothing. Do not disable the tracepoint, otherwise
                 * "soft enable"s (clearing the SOFT_DISABLED bit) wont work.
                 */
                if (soft_disable) {
                        if (atomic_dec_return(&file->sm_ref) > 0)
                                break;
                        disable = file->flags & FTRACE_EVENT_FL_SOFT_DISABLED;
                        clear_bit(FTRACE_EVENT_FL_SOFT_MODE_BIT, &file->flags);
                } else
                        disable = !(file->flags & FTRACE_EVENT_FL_SOFT_MODE);

                if (disable && (file->flags & FTRACE_EVENT_FL_ENABLED)) {
                        clear_bit(FTRACE_EVENT_FL_ENABLED_BIT, &file->flags);
                        if (file->flags & FTRACE_EVENT_FL_RECORDED_CMD) {
                                tracing_stop_cmdline_record();
                                clear_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags);
                        }
                        call->class->reg(call, TRACE_REG_UNREGISTER, file);
                }
                /* If in SOFT_MODE, just set the SOFT_DISABLE_BIT, else clear it */
                if (file->flags & FTRACE_EVENT_FL_SOFT_MODE)
                        set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags);
                else
                        clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags);
                break;
        case 1:
                /*
                 * When soft_disable is set and enable is set, we want to
                 * register the tracepoint for the event, but leave the event
                 * as is. That means, if the event was already enabled, we do
                 * nothing (but set SOFT_MODE). If the event is disabled, we
                 * set SOFT_DISABLED before enabling the event tracepoint, so
                 * it still seems to be disabled.
                 */
                if (!soft_disable)
                        clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags);
                else {
                        if (atomic_inc_return(&file->sm_ref) > 1)
                                break;
                        set_bit(FTRACE_EVENT_FL_SOFT_MODE_BIT, &file->flags);
                }

                if (!(file->flags & FTRACE_EVENT_FL_ENABLED)) {

                        /* Keep the event disabled, when going to SOFT_MODE. */
                        if (soft_disable)
                                set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &file->flags);

                        if (trace_flags & TRACE_ITER_RECORD_CMD) {
                                tracing_start_cmdline_record();
                                set_bit(FTRACE_EVENT_FL_RECORDED_CMD_BIT, &file->flags);
                        }
                        ret = call->class->reg(call, TRACE_REG_REGISTER, file);
                        if (ret) {
                                tracing_stop_cmdline_record();
                                pr_info("event trace: Could not enable event "
                                        "%s\n", ftrace_event_name(call));
                                break;
                        }
                        set_bit(FTRACE_EVENT_FL_ENABLED_BIT, &file->flags);

                        /* WAS_ENABLED gets set but never cleared. */
                        call->flags |= TRACE_EVENT_FL_WAS_ENABLED;
                }
                break;
        }

        return ret;
}

int trace_event_enable_disable(struct ftrace_event_file *file,
                               int enable, int soft_disable)
{
        return __ftrace_event_enable_disable(file, enable, soft_disable);
}

static int ftrace_event_enable_disable(struct ftrace_event_file *file,
                                       int enable)
{
        return __ftrace_event_enable_disable(file, enable, 0);
}

static void ftrace_clear_events(struct trace_array *tr)
{
        struct ftrace_event_file *file;

        mutex_lock(&event_mutex);
        list_for_each_entry(file, &tr->events, list) {
                ftrace_event_enable_disable(file, 0);
        }
        mutex_unlock(&event_mutex);
}

static void __put_system(struct event_subsystem *system)
{
        struct event_filter *filter = system->filter;

        WARN_ON_ONCE(system_refcount(system) == 0);
        if (system_refcount_dec(system))
                return;

        list_del(&system->list);

        if (filter) {
                kfree(filter->filter_string);
                kfree(filter);
        }
        if (system->ref_count & SYSTEM_FL_FREE_NAME)
                kfree(system->name);
        kfree(system);
}

static void __get_system(struct event_subsystem *system)
{
        WARN_ON_ONCE(system_refcount(system) == 0);
        system_refcount_inc(system);
}

static void __get_system_dir(struct ftrace_subsystem_dir *dir)
{
        WARN_ON_ONCE(dir->ref_count == 0);
        dir->ref_count++;
        __get_system(dir->subsystem);
}

static void __put_system_dir(struct ftrace_subsystem_dir *dir)
{
        WARN_ON_ONCE(dir->ref_count == 0);
        /* If the subsystem is about to be freed, the dir must be too */
        WARN_ON_ONCE(system_refcount(dir->subsystem) == 1 && dir->ref_count != 1);

        __put_system(dir->subsystem);
        if (!--dir->ref_count)
                kfree(dir);
}

static void put_system(struct ftrace_subsystem_dir *dir)
{
        mutex_lock(&event_mutex);
        __put_system_dir(dir);
        mutex_unlock(&event_mutex);
}

static void remove_subsystem(struct ftrace_subsystem_dir *dir)
{
        if (!dir)
                return;

        if (!--dir->nr_events) {
                tracefs_remove_recursive(dir->entry);
                list_del(&dir->list);
                __put_system_dir(dir);
        }
}

static void remove_event_file_dir(struct ftrace_event_file *file)
{
        struct dentry *dir = file->dir;
        struct dentry *child;

        if (dir) {
                spin_lock(&dir->d_lock);        /* probably unneeded */
                list_for_each_entry(child, &dir->d_subdirs, d_child) {
                        if (d_really_is_positive(child))        /* probably unneeded */
                                d_inode(child)->i_private = NULL;
                }
                spin_unlock(&dir->d_lock);

                tracefs_remove_recursive(dir);
        }

        list_del(&file->list);
        remove_subsystem(file->system);
        free_event_filter(file->filter);
        kmem_cache_free(file_cachep, file);
}

/*
 * __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
 */
static int
__ftrace_set_clr_event_nolock(struct trace_array *tr, const char *match,
                              const char *sub, const char *event, int set)
{
        struct ftrace_event_file *file;
        struct ftrace_event_call *call;
        const char *name;
        int ret = -EINVAL;

        list_for_each_entry(file, &tr->events, list) {

                call = file->event_call;
                name = ftrace_event_name(call);

                if (!name || !call->class || !call->class->reg)
                        continue;

                if (call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
                        continue;

                if (match &&
                    strcmp(match, name) != 0 &&
                    strcmp(match, call->class->system) != 0)
                        continue;

                if (sub && strcmp(sub, call->class->system) != 0)
                        continue;

                if (event && strcmp(event, name) != 0)
                        continue;

                ftrace_event_enable_disable(file, set);

                ret = 0;
        }

        return ret;
}

static int __ftrace_set_clr_event(struct trace_array *tr, const char *match,
                                  const char *sub, const char *event, int set)
{
        int ret;

        mutex_lock(&event_mutex);
        ret = __ftrace_set_clr_event_nolock(tr, match, sub, event, set);
        mutex_unlock(&event_mutex);

        return ret;
}

static int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)
{
        char *event = NULL, *sub = NULL, *match;
        int ret;

        /*
         * The buf format can be <subsystem>:<event-name>
         *  *:<event-name> means any event by that name.
         *  :<event-name> is the same.
         *
         *  <subsystem>:* means all events in that subsystem
         *  <subsystem>: means the same.
         *
         *  <name> (no ':') means all events in a subsystem with
         *  the name <name> or any event that matches <name>
         */

        match = strsep(&buf, ":");
        if (buf) {
                sub = match;
                event = buf;
                match = NULL;

                if (!strlen(sub) || strcmp(sub, "*") == 0)
                        sub = NULL;
                if (!strlen(event) || strcmp(event, "*") == 0)
                        event = NULL;
        }

        ret = __ftrace_set_clr_event(tr, match, sub, event, set);

        /* Put back the colon to allow this to be called again */
        if (buf)
                *(buf - 1) = ':';

        return ret;
}

/**
 * trace_set_clr_event - enable or disable an event
 * @system: system name to match (NULL for any system)
 * @event: event name to match (NULL for all events, within system)
 * @set: 1 to enable, 0 to disable
 *
 * This is a way for other parts of the kernel to enable or disable
 * event recording.
 *
 * Returns 0 on success, -EINVAL if the parameters do not match any
 * registered events.
 */
int trace_set_clr_event(const char *system, const char *event, int set)
{
        struct trace_array *tr = top_trace_array();

        if (!tr)
                return -ENODEV;

        return __ftrace_set_clr_event(tr, NULL, system, event, set);
}
EXPORT_SYMBOL_GPL(trace_set_clr_event);

/* 128 should be much more than enough */
#define EVENT_BUF_SIZE          127

static ssize_t
ftrace_event_write(struct file *file, const char __user *ubuf,
                   size_t cnt, loff_t *ppos)
{
        struct trace_parser parser;
        struct seq_file *m = file->private_data;
        struct trace_array *tr = m->private;
        ssize_t read, ret;

        if (!cnt)
                return 0;

        ret = tracing_update_buffers();
        if (ret < 0)
                return ret;

        if (trace_parser_get_init(&parser, EVENT_BUF_SIZE + 1))
                return -ENOMEM;

        read = trace_get_user(&parser, ubuf, cnt, ppos);

        if (read >= 0 && trace_parser_loaded((&parser))) {
                int set = 1;

                if (*parser.buffer == '!')
                        set = 0;

                parser.buffer[parser.idx] = 0;

                ret = ftrace_set_clr_event(tr, parser.buffer + !set, set);
                if (ret)
                        goto out_put;
        }

        ret = read;

 out_put:
        trace_parser_put(&parser);

        return ret;
}

static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct ftrace_event_file *file = v;
        struct ftrace_event_call *call;
        struct trace_array *tr = m->private;

        (*pos)++;

        list_for_each_entry_continue(file, &tr->events, list) {
                call = file->event_call;
                /*
                 * The ftrace subsystem is for showing formats only.
                 * They can not be enabled or disabled via the event files.
                 */
                if (call->class && call->class->reg)
                        return file;
        }

        return NULL;
}

static void *t_start(struct seq_file *m, loff_t *pos)
{
        struct ftrace_event_file *file;
        struct trace_array *tr = m->private;
        loff_t l;

        mutex_lock(&event_mutex);

        file = list_entry(&tr->events, struct ftrace_event_file, list);
        for (l = 0; l <= *pos; ) {
                file = t_next(m, file, &l);
                if (!file)
                        break;
        }
        return file;
}

static void *
s_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct ftrace_event_file *file = v;
        struct trace_array *tr = m->private;

        (*pos)++;

        list_for_each_entry_continue(file, &tr->events, list) {
                if (file->flags & FTRACE_EVENT_FL_ENABLED)
                        return file;
        }

        return NULL;
}

static void *s_start(struct seq_file *m, loff_t *pos)
{
        struct ftrace_event_file *file;
        struct trace_array *tr = m->private;
        loff_t l;

        mutex_lock(&event_mutex);

        file = list_entry(&tr->events, struct ftrace_event_file, list);
        for (l = 0; l <= *pos; ) {
                file = s_next(m, file, &l);
                if (!file)
                        break;
        }
        return file;
}

static int t_show(struct seq_file *m, void *v)
{
        struct ftrace_event_file *file = v;
        struct ftrace_event_call *call = file->event_call;

        if (strcmp(call->class->system, TRACE_SYSTEM) != 0)
                seq_printf(m, "%s:", call->class->system);
        seq_printf(m, "%s\n", ftrace_event_name(call));

        return 0;
}

static void t_stop(struct seq_file *m, void *p)
{
        mutex_unlock(&event_mutex);
}

static ssize_t
event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
                  loff_t *ppos)
{
        struct ftrace_event_file *file;
        unsigned long flags;
        char buf[4] = "0";

        mutex_lock(&event_mutex);
        file = event_file_data(filp);
        if (likely(file))
                flags = file->flags;
        mutex_unlock(&event_mutex);

        if (!file)
                return -ENODEV;

        if (flags & FTRACE_EVENT_FL_ENABLED &&
            !(flags & FTRACE_EVENT_FL_SOFT_DISABLED))
                strcpy(buf, "1");

        if (flags & FTRACE_EVENT_FL_SOFT_DISABLED ||
            flags & FTRACE_EVENT_FL_SOFT_MODE)
                strcat(buf, "*");

        strcat(buf, "\n");

        return simple_read_from_buffer(ubuf, cnt, ppos, buf, strlen(buf));
}

static ssize_t
event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
                   loff_t *ppos)
{
        struct ftrace_event_file *file;
        unsigned long val;
        int ret;

        ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
        if (ret)
                return ret;

        ret = tracing_update_buffers();
        if (ret < 0)
                return ret;

        switch (val) {
        case 0:
        case 1:
                ret = -ENODEV;
                mutex_lock(&event_mutex);
                file = event_file_data(filp);
                if (likely(file))
                        ret = ftrace_event_enable_disable(file, val);
                mutex_unlock(&event_mutex);
                break;

        default:
                return -EINVAL;
        }

        *ppos += cnt;

        return ret ? ret : cnt;
}

static ssize_t
system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
                   loff_t *ppos)
{
        const char set_to_char[4] = { '?', '0', '1', 'X' };
        struct ftrace_subsystem_dir *dir = filp->private_data;
        struct event_subsystem *system = dir->subsystem;
        struct ftrace_event_call *call;
        struct ftrace_event_file *file;
        struct trace_array *tr = dir->tr;
        char buf[2];
        int set = 0;
        int ret;

        mutex_lock(&event_mutex);
        list_for_each_entry(file, &tr->events, list) {
                call = file->event_call;
                if (!ftrace_event_name(call) || !call->class || !call->class->reg)
                        continue;

                if (system && strcmp(call->class->system, system->name) != 0)
                        continue;

                /*
                 * We need to find out if all the events are set
                 * or if all events or cleared, or if we have
                 * a mixture.
                 */
                set |= (1 << !!(file->flags & FTRACE_EVENT_FL_ENABLED));

                /*
                 * If we have a mixture, no need to look further.
                 */
                if (set == 3)
                        break;
        }
        mutex_unlock(&event_mutex);

        buf[0] = set_to_char[set];
        buf[1] = '\n';

        ret = simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);

        return ret;
}

static ssize_t
system_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
                    loff_t *ppos)
{
        struct ftrace_subsystem_dir *dir = filp->private_data;
        struct event_subsystem *system = dir->subsystem;
        const char *name = NULL;
        unsigned long val;
        ssize_t ret;

        ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
        if (ret)
                return ret;

        ret = tracing_update_buffers();
        if (ret < 0)
                return ret;

        if (val != 0 && val != 1)
                return -EINVAL;

        /*
         * Opening of "enable" adds a ref count to system,
         * so the name is safe to use.
         */
        if (system)
                name = system->name;

        ret = __ftrace_set_clr_event(dir->tr, NULL, name, NULL, val);
        if (ret)
                goto out;

        ret = cnt;

out:
        *ppos += cnt;

        return ret;
}

enum {
        FORMAT_HEADER           = 1,
        FORMAT_FIELD_SEPERATOR  = 2,
        FORMAT_PRINTFMT         = 3,
};

static void *f_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct ftrace_event_call *call = event_file_data(m->private);
        struct list_head *common_head = &ftrace_common_fields;
        struct list_head *head = trace_get_fields(call);
        struct list_head *node = v;

        (*pos)++;

        switch ((unsigned long)v) {
        case FORMAT_HEADER:
                node = common_head;
                break;

        case FORMAT_FIELD_SEPERATOR:
                node = head;
                break;

        case FORMAT_PRINTFMT:
                /* all done */
                return NULL;
        }

        node = node->prev;
        if (node == common_head)
                return (void *)FORMAT_FIELD_SEPERATOR;
        else if (node == head)
                return (void *)FORMAT_PRINTFMT;
        else
                return node;
}

static int f_show(struct seq_file *m, void *v)
{
        struct ftrace_event_call *call = event_file_data(m->private);
        struct ftrace_event_field *field;
        const char *array_descriptor;

        switch ((unsigned long)v) {
        case FORMAT_HEADER:
                seq_printf(m, "name: %s\n", ftrace_event_name(call));
                seq_printf(m, "ID: %d\n", call->event.type);
                seq_puts(m, "format:\n");
                return 0;

        case FORMAT_FIELD_SEPERATOR:
                seq_putc(m, '\n');
                return 0;

        case FORMAT_PRINTFMT:
                seq_printf(m, "\nprint fmt: %s\n",
                           call->print_fmt);
                return 0;
        }

        field = list_entry(v, struct ftrace_event_field, link);
        /*
         * Smartly shows the array type(except dynamic array).
         * Normal:
         *      field:TYPE VAR
         * If TYPE := TYPE[LEN], it is shown:
         *      field:TYPE VAR[LEN]
         */
        array_descriptor = strchr(field->type, '[');

        if (!strncmp(field->type, "__data_loc", 10))
                array_descriptor = NULL;

        if (!array_descriptor)
                seq_printf(m, "\tfield:%s %s;\toffset:%u;\tsize:%u;\tsigned:%d;\n",
                           field->type, field->name, field->offset,
                           field->size, !!field->is_signed);
        else
                seq_printf(m, "\tfield:%.*s %s%s;\toffset:%u;\tsize:%u;\tsigned:%d;\n",
                           (int)(array_descriptor - field->type),
                           field->type, field->name,
                           array_descriptor, field->offset,
                           field->size, !!field->is_signed);

        return 0;
}

static void *f_start(struct seq_file *m, loff_t *pos)
{
        void *p = (void *)FORMAT_HEADER;
        loff_t l = 0;

        /* ->stop() is called even if ->start() fails */
        mutex_lock(&event_mutex);
        if (!event_file_data(m->private))
                return ERR_PTR(-ENODEV);

        while (l < *pos && p)
                p = f_next(m, p, &l);

        return p;
}

static void f_stop(struct seq_file *m, void *p)
{
        mutex_unlock(&event_mutex);
}

static const struct seq_operations trace_format_seq_ops = {
        .start          = f_start,
        .next           = f_next,
        .stop           = f_stop,
        .show           = f_show,
};

static int trace_format_open(struct inode *inode, struct file *file)
{
        struct seq_file *m;
        int ret;

        ret = seq_open(file, &trace_format_seq_ops);
        if (ret < 0)
                return ret;

        m = file->private_data;
        m->private = file;

        return 0;
}

static ssize_t
event_id_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
{
        int id = (long)event_file_data(filp);
        char buf[32];
        int len;

        if (*ppos)
                return 0;

        if (unlikely(!id))
                return -ENODEV;

        len = sprintf(buf, "%d\n", id);

        return simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
}

static ssize_t
event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
                  loff_t *ppos)
{
        struct ftrace_event_file *file;
        struct trace_seq *s;
        int r = -ENODEV;

        if (*ppos)
                return 0;

        s = kmalloc(sizeof(*s), GFP_KERNEL);

        if (!s)
                return -ENOMEM;

        trace_seq_init(s);

        mutex_lock(&event_mutex);
        file = event_file_data(filp);
        if (file)
                print_event_filter(file, s);
        mutex_unlock(&event_mutex);

        if (file)
                r = simple_read_from_buffer(ubuf, cnt, ppos,
                                            s->buffer, trace_seq_used(s));

        kfree(s);

        return r;
}

static ssize_t
event_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
                   loff_t *ppos)
{
        struct ftrace_event_file *file;
        char *buf;
        int err = -ENODEV;

        if (cnt >= PAGE_SIZE)
                return -EINVAL;

        buf = (char *)__get_free_page(GFP_TEMPORARY);
        if (!buf)
                return -ENOMEM;

        if (copy_from_user(buf, ubuf, cnt)) {
                free_page((unsigned long) buf);
                return -EFAULT;
        }
        buf[cnt] = '\0';

        mutex_lock(&event_mutex);
        file = event_file_data(filp);
        if (file)
                err = apply_event_filter(file, buf);
        mutex_unlock(&event_mutex);

        free_page((unsigned long) buf);
        if (err < 0)
                return err;

        *ppos += cnt;

        return cnt;
}

static LIST_HEAD(event_subsystems);

static int subsystem_open(struct inode *inode, struct file *filp)
{
        struct event_subsystem *system = NULL;
        struct ftrace_subsystem_dir *dir = NULL; /* Initialize for gcc */
        struct trace_array *tr;
        int ret;

        if (tracing_is_disabled())
                return -ENODEV;

        /* Make sure the system still exists */
        mutex_lock(&trace_types_lock);
        mutex_lock(&event_mutex);
        list_for_each_entry(tr, &ftrace_trace_arrays, list) {
                list_for_each_entry(dir, &tr->systems, list) {
                        if (dir == inode->i_private) {
                                /* Don't open systems with no events */
                                if (dir->nr_events) {
                                        __get_system_dir(dir);
                                        system = dir->subsystem;
                                }
                                goto exit_loop;
                        }
                }
        }
 exit_loop:
        mutex_unlock(&event_mutex);
        mutex_unlock(&trace_types_lock);

        if (!system)
                return -ENODEV;

        /* Some versions of gcc think dir can be uninitialized here */
        WARN_ON(!dir);

        /* Still need to increment the ref count of the system */
        if (trace_array_get(tr) < 0) {
                put_system(dir);
                return -ENODEV;
        }

        ret = tracing_open_generic(inode, filp);
        if (ret < 0) {
                trace_array_put(tr);
                put_system(dir);
        }

        return ret;
}

static int system_tr_open(struct inode *inode, struct file *filp)
{
        struct ftrace_subsystem_dir *dir;
        struct trace_array *tr = inode->i_private;
        int ret;

        if (tracing_is_disabled())
                return -ENODEV;

        if (trace_array_get(tr) < 0)
                return -ENODEV;

        /* Make a temporary dir that has no system but points to tr */
        dir = kzalloc(sizeof(*dir), GFP_KERNEL);
        if (!dir) {
                trace_array_put(tr);
                return -ENOMEM;
        }

        dir->tr = tr;

        ret = tracing_open_generic(inode, filp);
        if (ret < 0) {
                trace_array_put(tr);
                kfree(dir);
                return ret;
        }

        filp->private_data = dir;

        return 0;
}

static int subsystem_release(struct inode *inode, struct file *file)
{
        struct ftrace_subsystem_dir *dir = file->private_data;

        trace_array_put(dir->tr);

        /*
         * If dir->subsystem is NULL, then this is a temporary
         * descriptor that was made for a trace_array to enable
         * all subsystems.
         */
        if (dir->subsystem)
                put_system(dir);
        else
                kfree(dir);

        return 0;
}

static ssize_t
subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
                      loff_t *ppos)
{
        struct ftrace_subsystem_dir *dir = filp->private_data;
        struct event_subsystem *system = dir->subsystem;
        struct trace_seq *s;
        int r;

        if (*ppos)
                return 0;

        s = kmalloc(sizeof(*s), GFP_KERNEL);
        if (!s)
                return -ENOMEM;

        trace_seq_init(s);

        print_subsystem_event_filter(system, s);
        r = simple_read_from_buffer(ubuf, cnt, ppos,
                                    s->buffer, trace_seq_used(s));

        kfree(s);

        return r;
}

static ssize_t
subsystem_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
                       loff_t *ppos)
{
        struct ftrace_subsystem_dir *dir = filp->private_data;
        char *buf;
        int err;

        if (cnt >= PAGE_SIZE)
                return -EINVAL;

        buf = (char *)__get_free_page(GFP_TEMPORARY);
        if (!buf)
                return -ENOMEM;

        if (copy_from_user(buf, ubuf, cnt)) {
                free_page((unsigned long) buf);
                return -EFAULT;
        }
        buf[cnt] = '\0';

        err = apply_subsystem_event_filter(dir, buf);
        free_page((unsigned long) buf);
        if (err < 0)
                return err;

        *ppos += cnt;

        return cnt;
}

static ssize_t
show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
{
        int (*func)(struct trace_seq *s) = filp->private_data;
        struct trace_seq *s;
        int r;

        if (*ppos)
                return 0;

        s = kmalloc(sizeof(*s), GFP_KERNEL);
        if (!s)
                return -ENOMEM;

        trace_seq_init(s);

        func(s);
        r = simple_read_from_buffer(ubuf, cnt, ppos,
                                    s->buffer, trace_seq_used(s));

        kfree(s);

        return r;
}

static int ftrace_event_avail_open(struct inode *inode, struct file *file);
static int ftrace_event_set_open(struct inode *inode, struct file *file);
static int ftrace_event_release(struct inode *inode, struct file *file);

static const struct seq_operations show_event_seq_ops = {
        .start = t_start,
        .next = t_next,
        .show = t_show,
        .stop = t_stop,
};

static const struct seq_operations show_set_event_seq_ops = {
        .start = s_start,
        .next = s_next,
        .show = t_show,
        .stop = t_stop,
};

static const struct file_operations ftrace_avail_fops = {
        .open = ftrace_event_avail_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = seq_release,
};

static const struct file_operations ftrace_set_event_fops = {
        .open = ftrace_event_set_open,
        .read = seq_read,
        .write = ftrace_event_write,
        .llseek = seq_lseek,
        .release = ftrace_event_release,
};

static const struct file_operations ftrace_enable_fops = {
        .open = tracing_open_generic,
        .read = event_enable_read,
        .write = event_enable_write,
        .llseek = default_llseek,
};

static const struct file_operations ftrace_event_format_fops = {
        .open = trace_format_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = seq_release,
};

static const struct file_operations ftrace_event_id_fops = {
        .read = event_id_read,
        .llseek = default_llseek,
};

static const struct file_operations ftrace_event_filter_fops = {
        .open = tracing_open_generic,
        .read = event_filter_read,
        .write = event_filter_write,
        .llseek = default_llseek,
};

static const struct file_operations ftrace_subsystem_filter_fops = {
        .open = subsystem_open,
        .read = subsystem_filter_read,
        .write = subsystem_filter_write,
        .llseek = default_llseek,
        .release = subsystem_release,
};

static const struct file_operations ftrace_system_enable_fops = {
        .open = subsystem_open,
        .read = system_enable_read,
        .write = system_enable_write,
        .llseek = default_llseek,
        .release = subsystem_release,
};

static const struct file_operations ftrace_tr_enable_fops = {
        .open = system_tr_open,
        .read = system_enable_read,
        .write = system_enable_write,
        .llseek = default_llseek,
        .release = subsystem_release,
};

static const struct file_operations ftrace_show_header_fops = {
        .open = tracing_open_generic,
        .read = show_header,
        .llseek = default_llseek,
};

static int
ftrace_event_open(struct inode *inode, struct file *file,
                  const struct seq_operations *seq_ops)
{
        struct seq_file *m;
        int ret;

        ret = seq_open(file, seq_ops);
        if (ret < 0)
                return ret;
        m = file->private_data;
        /* copy tr over to seq ops */
        m->private = inode->i_private;

        return ret;
}

static int ftrace_event_release(struct inode *inode, struct file *file)
{
        struct trace_array *tr = inode->i_private;

        trace_array_put(tr);

        return seq_release(inode, file);
}

static int
ftrace_event_avail_open(struct inode *inode, struct file *file)
{
        const struct seq_operations *seq_ops = &show_event_seq_ops;

        return ftrace_event_open(inode, file, seq_ops);
}

static int
ftrace_event_set_open(struct inode *inode, struct file *file)
{
        const struct seq_operations *seq_ops = &show_set_event_seq_ops;
        struct trace_array *tr = inode->i_private;
        int ret;

        if (trace_array_get(tr) < 0)
                return -ENODEV;

        if ((file->f_mode & FMODE_WRITE) &&
            (file->f_flags & O_TRUNC))
                ftrace_clear_events(tr);

        ret = ftrace_event_open(inode, file, seq_ops);
        if (ret < 0)
                trace_array_put(tr);
        return ret;
}

static struct event_subsystem *
create_new_subsystem(const char *name)
{
        struct event_subsystem *system;

        /* need to create new entry */
        system = kmalloc(sizeof(*system), GFP_KERNEL);
        if (!system)
                return NULL;

        system->ref_count = 1;

        /* Only allocate if dynamic (kprobes and modules) */
        if (!core_kernel_data((unsigned long)name)) {
                system->ref_count |= SYSTEM_FL_FREE_NAME;
                system->name = kstrdup(name, GFP_KERNEL);
                if (!system->name)
                        goto out_free;
        } else
                system->name = name;

        system->filter = NULL;

        system->filter = kzalloc(sizeof(struct event_filter), GFP_KERNEL);
        if (!system->filter)
                goto out_free;

        list_add(&system->list, &event_subsystems);

        return system;

 out_free:
        if (system->ref_count & SYSTEM_FL_FREE_NAME)
                kfree(system->name);
        kfree(system);
        return NULL;
}

static struct dentry *
event_subsystem_dir(struct trace_array *tr, const char *name,
                    struct ftrace_event_file *file, struct dentry *parent)
{
        struct ftrace_subsystem_dir *dir;
        struct event_subsystem *system;
        struct dentry *entry;

        /* First see if we did not already create this dir */
        list_for_each_entry(dir, &tr->systems, list) {
                system = dir->subsystem;
                if (strcmp(system->name, name) == 0) {
                        dir->nr_events++;
                        file->system = dir;
                        return dir->entry;
                }
        }

        /* Now see if the system itself exists. */
        list_for_each_entry(system, &event_subsystems, list) {
                if (strcmp(system->name, name) == 0)
                        break;
        }
        /* Reset system variable when not found */
        if (&system->list == &event_subsystems)
                system = NULL;

        dir = kmalloc(sizeof(*dir), GFP_KERNEL);
        if (!dir)
                goto out_fail;

        if (!system) {
                system = create_new_subsystem(name);
                if (!system)
                        goto out_free;
        } else
                __get_system(system);

        dir->entry = tracefs_create_dir(name, parent);
        if (!dir->entry) {
                pr_warn("Failed to create system directory %s\n", name);
                __put_system(system);
                goto out_free;
        }

        dir->tr = tr;
        dir->ref_count = 1;
        dir->nr_events = 1;
        dir->subsystem = system;
        file->system = dir;

        entry = tracefs_create_file("filter", 0644, dir->entry, dir,
                                    &ftrace_subsystem_filter_fops);
        if (!entry) {
                kfree(system->filter);
                system->filter = NULL;
                pr_warn("Could not create tracefs '%s/filter' entry\n", name);
        }

        trace_create_file("enable", 0644, dir->entry, dir,
                          &ftrace_system_enable_fops);

        list_add(&dir->list, &tr->systems);

        return dir->entry;

 out_free:
        kfree(dir);
 out_fail:
        /* Only print this message if failed on memory allocation */
        if (!dir || !system)
                pr_warn("No memory to create event subsystem %s\n", name);
        return NULL;
}

static int
event_create_dir(struct dentry *parent, struct ftrace_event_file *file)
{
        struct ftrace_event_call *call = file->event_call;
        struct trace_array *tr = file->tr;
        struct list_head *head;
        struct dentry *d_events;
        const char *name;
        int ret;

        /*
         * If the trace point header did not define TRACE_SYSTEM
         * then the system would be called "TRACE_SYSTEM".
         */
        if (strcmp(call->class->system, TRACE_SYSTEM) != 0) {
                d_events = event_subsystem_dir(tr, call->class->system, file, parent);
                if (!d_events)
                        return -ENOMEM;
        } else
                d_events = parent;

        name = ftrace_event_name(call);
        file->dir = tracefs_create_dir(name, d_events);
        if (!file->dir) {
                pr_warn("Could not create tracefs '%s' directory\n", name);
                return -1;
        }

        if (call->class->reg && !(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE))
                trace_create_file("enable", 0644, file->dir, file,
                                  &ftrace_enable_fops);

#ifdef CONFIG_PERF_EVENTS
        if (call->event.type && call->class->reg)
                trace_create_file("id", 0444, file->dir,
                                  (void *)(long)call->event.type,
                                  &ftrace_event_id_fops);
#endif

        /*
         * Other events may have the same class. Only update
         * the fields if they are not already defined.
         */
        head = trace_get_fields(call);
        if (list_empty(head)) {
                ret = call->class->define_fields(call);
                if (ret < 0) {
                        pr_warn("Could not initialize trace point events/%s\n",
                                name);
                        return -1;
                }
        }
        trace_create_file("filter", 0644, file->dir, file,
                          &ftrace_event_filter_fops);

        trace_create_file("trigger", 0644, file->dir, file,
                          &event_trigger_fops);

        trace_create_file("format", 0444, file->dir, call,
                          &ftrace_event_format_fops);

        return 0;
}

static void remove_event_from_tracers(struct ftrace_event_call *call)
{
        struct ftrace_event_file *file;
        struct trace_array *tr;

        do_for_each_event_file_safe(tr, file) {
                if (file->event_call != call)
                        continue;

                remove_event_file_dir(file);
                /*
                 * The do_for_each_event_file_safe() is
                 * a double loop. After finding the call for this
                 * trace_array, we use break to jump to the next
                 * trace_array.
                 */
                break;
        } while_for_each_event_file();
}

static void event_remove(struct ftrace_event_call *call)
{
        struct trace_array *tr;
        struct ftrace_event_file *file;

        do_for_each_event_file(tr, file) {
                if (file->event_call != call)
                        continue;
                ftrace_event_enable_disable(file, 0);
                /*
                 * The do_for_each_event_file() is
                 * a double loop. After finding the call for this
                 * trace_array, we use break to jump to the next
                 * trace_array.
                 */
                break;
        } while_for_each_event_file();

        if (call->event.funcs)
                __unregister_ftrace_event(&call->event);
        remove_event_from_tracers(call);
        list_del(&call->list);
}

static int event_init(struct ftrace_event_call *call)
{
        int ret = 0;
        const char *name;

        name = ftrace_event_name(call);
        if (WARN_ON(!name))
                return -EINVAL;

        if (call->class->raw_init) {
                ret = call->class->raw_init(call);
                if (ret < 0 && ret != -ENOSYS)
                        pr_warn("Could not initialize trace events/%s\n", name);
        }

        return ret;
}

static int
__register_event(struct ftrace_event_call *call, struct module *mod)
{
        int ret;

        ret = event_init(call);
        if (ret < 0)
                return ret;

        list_add(&call->list, &ftrace_events);
        call->mod = mod;

        return 0;
}

static char *enum_replace(char *ptr, struct trace_enum_map *map, int len)
{
        int rlen;
        int elen;

        /* Find the length of the enum value as a string */
        elen = snprintf(ptr, 0, "%ld", map->enum_value);
        /* Make sure there's enough room to replace the string with the value */
        if (len < elen)
                return NULL;

        snprintf(ptr, elen + 1, "%ld", map->enum_value);

        /* Get the rest of the string of ptr */
        rlen = strlen(ptr + len);
        memmove(ptr + elen, ptr + len, rlen);
        /* Make sure we end the new string */
        ptr[elen + rlen] = 0;

        return ptr + elen;
}

static void update_event_printk(struct ftrace_event_call *call,
                                struct trace_enum_map *map)
{
        char *ptr;
        int quote = 0;
        int len = strlen(map->enum_string);

        for (ptr = call->print_fmt; *ptr; ptr++) {
                if (*ptr == '\\') {
                        ptr++;
                        /* paranoid */
                        if (!*ptr)
                                break;
                        continue;
                }
                if (*ptr == '"') {
                        quote ^= 1;
                        continue;
                }
                if (quote)
                        continue;
                if (isdigit(*ptr)) {
                        /* skip numbers */
                        do {
                                ptr++;
                                /* Check for alpha chars like ULL */
                        } while (isalnum(*ptr));
                        if (!*ptr)
                                break;
                        /*
                         * A number must have some kind of delimiter after
                         * it, and we can ignore that too.
                         */
                        continue;
                }
                if (isalpha(*ptr) || *ptr == '_') {
                        if (strncmp(map->enum_string, ptr, len) == 0 &&
                            !isalnum(ptr[len]) && ptr[len] != '_') {
                                ptr = enum_replace(ptr, map, len);
                                /* Hmm, enum string smaller than value */
                                if (WARN_ON_ONCE(!ptr))
                                        return;
                                /*
                                 * No need to decrement here, as enum_replace()
                                 * returns the pointer to the character passed
                                 * the enum, and two enums can not be placed
                                 * back to back without something in between.
                                 * We can skip that something in between.
                                 */
                                continue;
                        }
                skip_more:
                        do {
                                ptr++;
                        } while (isalnum(*ptr) || *ptr == '_');
                        if (!*ptr)
                                break;
                        /*
                         * If what comes after this variable is a '.' or
                         * '->' then we can continue to ignore that string.
                         */
                        if (*ptr == '.' || (ptr[0] == '-' && ptr[1] == '>')) {
                                ptr += *ptr == '.' ? 1 : 2;
                                if (!*ptr)
                                        break;
                                goto skip_more;
                        }
                        /*
                         * Once again, we can skip the delimiter that came
                         * after the string.
                         */
                        continue;
                }
        }
}

void trace_event_enum_update(struct trace_enum_map **map, int len)
{
        struct ftrace_event_call *call, *p;
        const char *last_system = NULL;
        int last_i;
        int i;

        down_write(&trace_event_sem);
        list_for_each_entry_safe(call, p, &ftrace_events, list) {
                /* events are usually grouped together with systems */
                if (!last_system || call->class->system != last_system) {
                        last_i = 0;
                        last_system = call->class->system;
                }

                for (i = last_i; i < len; i++) {
                        if (call->class->system == map[i]->system) {
                                /* Save the first system if need be */
                                if (!last_i)
                                        last_i = i;
                                update_event_printk(call, map[i]);
                        }
                }
        }
        up_write(&trace_event_sem);
}

static struct ftrace_event_file *
trace_create_new_event(struct ftrace_event_call *call,
                       struct trace_array *tr)
{
        struct ftrace_event_file *file;

        file = kmem_cache_alloc(file_cachep, GFP_TRACE);
        if (!file)
                return NULL;

        file->event_call = call;
        file->tr = tr;
        atomic_set(&file->sm_ref, 0);
        atomic_set(&file->tm_ref, 0);
        INIT_LIST_HEAD(&file->triggers);
        list_add(&file->list, &tr->events);

        return file;
}

/* Add an event to a trace directory */
static int
__trace_add_new_event(struct ftrace_event_call *call, struct trace_array *tr)
{
        struct ftrace_event_file *file;

        file = trace_create_new_event(call, tr);
        if (!file)
                return -ENOMEM;

        return event_create_dir(tr->event_dir, file);
}

/*
 * Just create a decriptor for early init. A descriptor is required
 * for enabling events at boot. We want to enable events before
 * the filesystem is initialized.
 */
static __init int
__trace_early_add_new_event(struct ftrace_event_call *call,
                            struct trace_array *tr)
{
        struct ftrace_event_file *file;

        file = trace_create_new_event(call, tr);
        if (!file)
                return -ENOMEM;

        return 0;
}

struct ftrace_module_file_ops;
static void __add_event_to_tracers(struct ftrace_event_call *call);

/* Add an additional event_call dynamically */
int trace_add_event_call(struct ftrace_event_call *call)
{
        int ret;
        mutex_lock(&trace_types_lock);
        mutex_lock(&event_mutex);

        ret = __register_event(call, NULL);
        if (ret >= 0)
                __add_event_to_tracers(call);

        mutex_unlock(&event_mutex);
        mutex_unlock(&trace_types_lock);
        return ret;
}

/*
 * Must be called under locking of trace_types_lock, event_mutex and
 * trace_event_sem.
 */
static void __trace_remove_event_call(struct ftrace_event_call *call)
{
        event_remove(call);
        trace_destroy_fields(call);
        free_event_filter(call->filter);
        call->filter = NULL;
}

static int probe_remove_event_call(struct ftrace_event_call *call)
{
        struct trace_array *tr;
        struct ftrace_event_file *file;

#ifdef CONFIG_PERF_EVENTS
        if (call->perf_refcount)
                return -EBUSY;
#endif
        do_for_each_event_file(tr, file) {
                if (file->event_call != call)
                        continue;
                /*
                 * We can't rely on ftrace_event_enable_disable(enable => 0)
                 * we are going to do, FTRACE_EVENT_FL_SOFT_MODE can suppress
                 * TRACE_REG_UNREGISTER.
                 */
                if (file->flags & FTRACE_EVENT_FL_ENABLED)
                        return -EBUSY;
                /*
                 * The do_for_each_event_file_safe() is
                 * a double loop. After finding the call for this
                 * trace_array, we use break to jump to the next
                 * trace_array.
                 */
                break;
        } while_for_each_event_file();

        __trace_remove_event_call(call);

        return 0;
}

/* Remove an event_call */
int trace_remove_event_call(struct ftrace_event_call *call)
{
        int ret;

        mutex_lock(&trace_types_lock);
        mutex_lock(&event_mutex);
        down_write(&trace_event_sem);
        ret = probe_remove_event_call(call);
        up_write(&trace_event_sem);
        mutex_unlock(&event_mutex);
        mutex_unlock(&trace_types_lock);

        return ret;
}

#define for_each_event(event, start, end)                       \
        for (event = start;                                     \
             (unsigned long)event < (unsigned long)end;         \
             event++)

#ifdef CONFIG_MODULES

static void trace_module_add_events(struct module *mod)
{
        struct ftrace_event_call **call, **start, **end;

        if (!mod->num_trace_events)
                return;

        /* Don't add infrastructure for mods without tracepoints */
        if (trace_module_has_bad_taint(mod)) {
                pr_err("%s: module has bad taint, not creating trace events\n",
                       mod->name);
                return;
        }

        start = mod->trace_events;
        end = mod->trace_events + mod->num_trace_events;

        for_each_event(call, start, end) {
                __register_event(*call, mod);
                __add_event_to_tracers(*call);
        }
}

static void trace_module_remove_events(struct module *mod)
{
        struct ftrace_event_call *call, *p;
        bool clear_trace = false;

        down_write(&trace_event_sem);
        list_for_each_entry_safe(call, p, &ftrace_events, list) {
                if (call->mod == mod) {
                        if (call->flags & TRACE_EVENT_FL_WAS_ENABLED)
                                clear_trace = true;
                        __trace_remove_event_call(call);
                }
        }
        up_write(&trace_event_sem);

        /*
         * It is safest to reset the ring buffer if the module being unloaded
         * registered any events that were used. The only worry is if
         * a new module gets loaded, and takes on the same id as the events
         * of this module. When printing out the buffer, traced events left
         * over from this module may be passed to the new module events and
         * unexpected results may occur.
         */
        if (clear_trace)
                tracing_reset_all_online_cpus();
}

static int trace_module_notify(struct notifier_block *self,
                               unsigned long val, void *data)
{
        struct module *mod = data;

        mutex_lock(&trace_types_lock);
        mutex_lock(&event_mutex);
        switch (val) {
        case MODULE_STATE_COMING:
                trace_module_add_events(mod);
                break;
        case MODULE_STATE_GOING:
                trace_module_remove_events(mod);
                break;
        }
        mutex_unlock(&event_mutex);
        mutex_unlock(&trace_types_lock);

        return 0;
}

static struct notifier_block trace_module_nb = {
        .notifier_call = trace_module_notify,
        .priority = 1, /* higher than trace.c module notify */
};
#endif /* CONFIG_MODULES */

/* Create a new event directory structure for a trace directory. */
static void
__trace_add_event_dirs(struct trace_array *tr)
{
        struct ftrace_event_call *call;
        int ret;

        list_for_each_entry(call, &ftrace_events, list) {
                ret = __trace_add_new_event(call, tr);
                if (ret < 0)
                        pr_warn("Could not create directory for event %s\n",
                                ftrace_event_name(call));
        }
}

struct ftrace_event_file *
find_event_file(struct trace_array *tr, const char *system,  const char *event)
{
        struct ftrace_event_file *file;
        struct ftrace_event_call *call;
        const char *name;

        list_for_each_entry(file, &tr->events, list) {

                call = file->event_call;
                name = ftrace_event_name(call);

                if (!name || !call->class || !call->class->reg)
                        continue;

                if (call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
                        continue;

                if (strcmp(event, name) == 0 &&
                    strcmp(system, call->class->system) == 0)
                        return file;
        }
        return NULL;
}

#ifdef CONFIG_DYNAMIC_FTRACE

/* Avoid typos */
#define ENABLE_EVENT_STR        "enable_event"
#define DISABLE_EVENT_STR       "disable_event"

struct event_probe_data {
        struct ftrace_event_file        *file;
        unsigned long                   count;
        int                             ref;
        bool                            enable;
};

static void
event_enable_probe(unsigned long ip, unsigned long parent_ip, void **_data)
{
        struct event_probe_data **pdata = (struct event_probe_data **)_data;
        struct event_probe_data *data = *pdata;

        if (!data)
                return;

        if (data->enable)
                clear_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &data->file->flags);
        else
                set_bit(FTRACE_EVENT_FL_SOFT_DISABLED_BIT, &data->file->flags);
}

static void
event_enable_count_probe(unsigned long ip, unsigned long parent_ip, void **_data)
{
        struct event_probe_data **pdata = (struct event_probe_data **)_data;
        struct event_probe_data *data = *pdata;

        if (!data)
                return;

        if (!data->count)
                return;

        /* Skip if the event is in a state we want to switch to */
        if (data->enable == !(data->file->flags & FTRACE_EVENT_FL_SOFT_DISABLED))
                return;

        if (data->count != -1)
                (data->count)--;

        event_enable_probe(ip, parent_ip, _data);
}

static int
event_enable_print(struct seq_file *m, unsigned long ip,
                      struct ftrace_probe_ops *ops, void *_data)
{
        struct event_probe_data *data = _data;

        seq_printf(m, "%ps:", (void *)ip);

        seq_printf(m, "%s:%s:%s",
                   data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
                   data->file->event_call->class->system,
                   ftrace_event_name(data->file->event_call));

        if (data->count == -1)
                seq_puts(m, ":unlimited\n");
        else
                seq_printf(m, ":count=%ld\n", data->count);

        return 0;
}

static int
event_enable_init(struct ftrace_probe_ops *ops, unsigned long ip,
                  void **_data)
{
        struct event_probe_data **pdata = (struct event_probe_data **)_data;
        struct event_probe_data *data = *pdata;

        data->ref++;
        return 0;
}

static void
event_enable_free(struct ftrace_probe_ops *ops, unsigned long ip,
                  void **_data)
{
        struct event_probe_data **pdata = (struct event_probe_data **)_data;
        struct event_probe_data *data = *pdata;

        if (WARN_ON_ONCE(data->ref <= 0))
                return;

        data->ref--;
        if (!data->ref) {
                /* Remove the SOFT_MODE flag */
                __ftrace_event_enable_disable(data->file, 0, 1);
                module_put(data->file->event_call->mod);
                kfree(data);
        }
        *pdata = NULL;
}

static struct ftrace_probe_ops event_enable_probe_ops = {
        .func                   = event_enable_probe,
        .print                  = event_enable_print,
        .init                   = event_enable_init,
        .free                   = event_enable_free,
};

static struct ftrace_probe_ops event_enable_count_probe_ops = {
        .func                   = event_enable_count_probe,
        .print                  = event_enable_print,
        .init                   = event_enable_init,
        .free                   = event_enable_free,
};

static struct ftrace_probe_ops event_disable_probe_ops = {
        .func                   = event_enable_probe,
        .print                  = event_enable_print,
        .init                   = event_enable_init,
        .free                   = event_enable_free,
};

static struct ftrace_probe_ops event_disable_count_probe_ops = {
        .func                   = event_enable_count_probe,
        .print                  = event_enable_print,
        .init                   = event_enable_init,
        .free                   = event_enable_free,
};

static int
event_enable_func(struct ftrace_hash *hash,
                  char *glob, char *cmd, char *param, int enabled)
{
        struct trace_array *tr = top_trace_array();
        struct ftrace_event_file *file;
        struct ftrace_probe_ops *ops;
        struct event_probe_data *data;
        const char *system;
        const char *event;
        char *number;
        bool enable;
        int ret;

        if (!tr)
                return -ENODEV;

        /* hash funcs only work with set_ftrace_filter */
        if (!enabled || !param)
                return -EINVAL;

        system = strsep(&param, ":");
        if (!param)
                return -EINVAL;

        event = strsep(&param, ":");

        mutex_lock(&event_mutex);

        ret = -EINVAL;
        file = find_event_file(tr, system, event);
        if (!file)
                goto out;

        enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;

        if (enable)
                ops = param ? &event_enable_count_probe_ops : &event_enable_probe_ops;
        else
                ops = param ? &event_disable_count_probe_ops : &event_disable_probe_ops;

        if (glob[0] == '!') {
                unregister_ftrace_function_probe_func(glob+1, ops);
                ret = 0;
                goto out;
        }

        ret = -ENOMEM;
        data = kzalloc(sizeof(*data), GFP_KERNEL);
        if (!data)
                goto out;

        data->enable = enable;
        data->count = -1;
        data->file = file;

        if (!param)
                goto out_reg;

        number = strsep(&param, ":");

        ret = -EINVAL;
        if (!strlen(number))
                goto out_free;

        /*
         * We use the callback data field (which is a pointer)
         * as our counter.
         */
        ret = kstrtoul(number, 0, &data->count);
        if (ret)
                goto out_free;

 out_reg:
        /* Don't let event modules unload while probe registered */
        ret = try_module_get(file->event_call->mod);
        if (!ret) {
                ret = -EBUSY;
                goto out_free;
        }

        ret = __ftrace_event_enable_disable(file, 1, 1);
        if (ret < 0)
                goto out_put;
        ret = register_ftrace_function_probe(glob, ops, data);
        /*
         * The above returns on success the # of functions enabled,
         * but if it didn't find any functions it returns zero.
         * Consider no functions a failure too.
         */
        if (!ret) {
                ret = -ENOENT;
                goto out_disable;
        } else if (ret < 0)
                goto out_disable;
        /* Just return zero, not the number of enabled functions */
        ret = 0;
 out:
        mutex_unlock(&event_mutex);
        return ret;

 out_disable:
        __ftrace_event_enable_disable(file, 0, 1);
 out_put:
        module_put(file->event_call->mod);
 out_free:
        kfree(data);
        goto out;
}

static struct ftrace_func_command event_enable_cmd = {
        .name                   = ENABLE_EVENT_STR,
        .func                   = event_enable_func,
};

static struct ftrace_func_command event_disable_cmd = {
        .name                   = DISABLE_EVENT_STR,
        .func                   = event_enable_func,
};

static __init int register_event_cmds(void)
{
        int ret;

        ret = register_ftrace_command(&event_enable_cmd);
        if (WARN_ON(ret < 0))
                return ret;
        ret = register_ftrace_command(&event_disable_cmd);
        if (WARN_ON(ret < 0))
                unregister_ftrace_command(&event_enable_cmd);
        return ret;
}
#else
static inline int register_event_cmds(void) { return 0; }
#endif /* CONFIG_DYNAMIC_FTRACE */

/*
 * The top level array has already had its ftrace_event_file
 * descriptors created in order to allow for early events to
 * be recorded. This function is called after the tracefs has been
 * initialized, and we now have to create the files associated
 * to the events.
 */
static __init void
__trace_early_add_event_dirs(struct trace_array *tr)
{
        struct ftrace_event_file *file;
        int ret;


        list_for_each_entry(file, &tr->events, list) {
                ret = event_create_dir(tr->event_dir, file);
                if (ret < 0)
                        pr_warn("Could not create directory for event %s\n",
                                ftrace_event_name(file->event_call));
        }
}

/*
 * For early boot up, the top trace array requires to have
 * a list of events that can be enabled. This must be done before
 * the filesystem is set up in order to allow events to be traced
 * early.
 */
static __init void
__trace_early_add_events(struct trace_array *tr)
{
        struct ftrace_event_call *call;
        int ret;

        list_for_each_entry(call, &ftrace_events, list) {
                /* Early boot up should not have any modules loaded */
                if (WARN_ON_ONCE(call->mod))
                        continue;

                ret = __trace_early_add_new_event(call, tr);
                if (ret < 0)
                        pr_warn("Could not create early event %s\n",
                                ftrace_event_name(call));
        }
}

/* Remove the event directory structure for a trace directory. */
static void
__trace_remove_event_dirs(struct trace_array *tr)
{
        struct ftrace_event_file *file, *next;

        list_for_each_entry_safe(file, next, &tr->events, list)
                remove_event_file_dir(file);
}

static void __add_event_to_tracers(struct ftrace_event_call *call)
{
        struct trace_array *tr;

        list_for_each_entry(tr, &ftrace_trace_arrays, list)
                __trace_add_new_event(call, tr);
}

extern struct ftrace_event_call *__start_ftrace_events[];
extern struct ftrace_event_call *__stop_ftrace_events[];

static char bootup_event_buf[COMMAND_LINE_SIZE] __initdata;

static __init int setup_trace_event(char *str)
{
        strlcpy(bootup_event_buf, str, COMMAND_LINE_SIZE);
        ring_buffer_expanded = true;
        tracing_selftest_disabled = true;

        return 1;
}
__setup("trace_event=", setup_trace_event);

/* Expects to have event_mutex held when called */
static int
create_event_toplevel_files(struct dentry *parent, struct trace_array *tr)
{
        struct dentry *d_events;
        struct dentry *entry;

        entry = tracefs_create_file("set_event", 0644, parent,
                                    tr, &ftrace_set_event_fops);
        if (!entry) {
                pr_warn("Could not create tracefs 'set_event' entry\n");
                return -ENOMEM;
        }

        d_events = tracefs_create_dir("events", parent);
        if (!d_events) {
                pr_warn("Could not create tracefs 'events' directory\n");
                return -ENOMEM;
        }

        /* ring buffer internal formats */
        trace_create_file("header_page", 0444, d_events,
                          ring_buffer_print_page_header,
                          &ftrace_show_header_fops);

        trace_create_file("header_event", 0444, d_events,
                          ring_buffer_print_entry_header,
                          &ftrace_show_header_fops);

        trace_create_file("enable", 0644, d_events,
                          tr, &ftrace_tr_enable_fops);

        tr->event_dir = d_events;

        return 0;
}

/**
 * event_trace_add_tracer - add a instance of a trace_array to events
 * @parent: The parent dentry to place the files/directories for events in
 * @tr: The trace array associated with these events
 *
 * When a new instance is created, it needs to set up its events
 * directory, as well as other files associated with events. It also
 * creates the event hierachry in the @parent/events directory.
 *
 * Returns 0 on success.
 */
int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr)
{
        int ret;

        mutex_lock(&event_mutex);

        ret = create_event_toplevel_files(parent, tr);
        if (ret)
                goto out_unlock;

        down_write(&trace_event_sem);
        __trace_add_event_dirs(tr);
        up_write(&trace_event_sem);

 out_unlock:
        mutex_unlock(&event_mutex);

        return ret;
}

/*
 * The top trace array already had its file descriptors created.
 * Now the files themselves need to be created.
 */
static __init int
early_event_add_tracer(struct dentry *parent, struct trace_array *tr)
{
        int ret;

        mutex_lock(&event_mutex);

        ret = create_event_toplevel_files(parent, tr);
        if (ret)
                goto out_unlock;

        down_write(&trace_event_sem);
        __trace_early_add_event_dirs(tr);
        up_write(&trace_event_sem);

 out_unlock:
        mutex_unlock(&event_mutex);

        return ret;
}

int event_trace_del_tracer(struct trace_array *tr)
{
        mutex_lock(&event_mutex);

        /* Disable any event triggers and associated soft-disabled events */
        clear_event_triggers(tr);

        /* Disable any running events */
        __ftrace_set_clr_event_nolock(tr, NULL, NULL, NULL, 0);

        /* Access to events are within rcu_read_lock_sched() */
        synchronize_sched();

        down_write(&trace_event_sem);
        __trace_remove_event_dirs(tr);
        tracefs_remove_recursive(tr->event_dir);
        up_write(&trace_event_sem);

        tr->event_dir = NULL;

        mutex_unlock(&event_mutex);

        return 0;
}

static __init int event_trace_memsetup(void)
{
        field_cachep = KMEM_CACHE(ftrace_event_field, SLAB_PANIC);
        file_cachep = KMEM_CACHE(ftrace_event_file, SLAB_PANIC);
        return 0;
}

static __init void
early_enable_events(struct trace_array *tr, bool disable_first)
{
        char *buf = bootup_event_buf;
        char *token;
        int ret;

        while (true) {
                token = strsep(&buf, ",");

                if (!token)
                        break;
                if (!*token)
                        continue;

                /* Restarting syscalls requires that we stop them first */
                if (disable_first)
                        ftrace_set_clr_event(tr, token, 0);

                ret = ftrace_set_clr_event(tr, token, 1);
                if (ret)
                        pr_warn("Failed to enable trace event: %s\n", token);

                /* Put back the comma to allow this to be called again */
                if (buf)
                        *(buf - 1) = ',';
        }
}

static __init int event_trace_enable(void)
{
        struct trace_array *tr = top_trace_array();
        struct ftrace_event_call **iter, *call;
        int ret;

        if (!tr)
                return -ENODEV;

        for_each_event(iter, __start_ftrace_events, __stop_ftrace_events) {

                call = *iter;
                ret = event_init(call);
                if (!ret)
                        list_add(&call->list, &ftrace_events);
        }

        /*
         * We need the top trace array to have a working set of trace
         * points at early init, before the debug files and directories
         * are created. Create the file entries now, and attach them
         * to the actual file dentries later.
         */
        __trace_early_add_events(tr);

        early_enable_events(tr, false);

        trace_printk_start_comm();

        register_event_cmds();

        register_trigger_cmds();

        return 0;
}

/*
 * event_trace_enable() is called from trace_event_init() first to
 * initialize events and perhaps start any events that are on the
 * command line. Unfortunately, there are some events that will not
 * start this early, like the system call tracepoints that need
 * to set the TIF_SYSCALL_TRACEPOINT flag of pid 1. But event_trace_enable()
 * is called before pid 1 starts, and this flag is never set, making
 * the syscall tracepoint never get reached, but the event is enabled
 * regardless (and not doing anything).
 */
static __init int event_trace_enable_again(void)
{
        struct trace_array *tr;

        tr = top_trace_array();
        if (!tr)
                return -ENODEV;

        early_enable_events(tr, true);

        return 0;
}

early_initcall(event_trace_enable_again);

static __init int event_trace_init(void)
{
        struct trace_array *tr;
        struct dentry *d_tracer;
        struct dentry *entry;
        int ret;

        tr = top_trace_array();
        if (!tr)
                return -ENODEV;

        d_tracer = tracing_init_dentry();
        if (IS_ERR(d_tracer))
                return 0;

        entry = tracefs_create_file("available_events", 0444, d_tracer,
                                    tr, &ftrace_avail_fops);
        if (!entry)
                pr_warn("Could not create tracefs 'available_events' entry\n");

        if (trace_define_common_fields())
                pr_warn("tracing: Failed to allocate common fields");

        ret = early_event_add_tracer(d_tracer, tr);
        if (ret)
                return ret;

#ifdef CONFIG_MODULES
        ret = register_module_notifier(&trace_module_nb);
        if (ret)
                pr_warn("Failed to register trace events module notifier\n");
#endif
        return 0;
}

void __init trace_event_init(void)
{
        event_trace_memsetup();
        init_ftrace_syscalls();
        event_trace_enable();
}

fs_initcall(event_trace_init);

#ifdef CONFIG_FTRACE_STARTUP_TEST

static DEFINE_SPINLOCK(test_spinlock);
static DEFINE_SPINLOCK(test_spinlock_irq);
static DEFINE_MUTEX(test_mutex);

static __init void test_work(struct work_struct *dummy)
{
        spin_lock(&test_spinlock);
        spin_lock_irq(&test_spinlock_irq);
        udelay(1);
        spin_unlock_irq(&test_spinlock_irq);
        spin_unlock(&test_spinlock);

        mutex_lock(&test_mutex);
        msleep(1);
        mutex_unlock(&test_mutex);
}

static __init int event_test_thread(void *unused)
{
        void *test_malloc;

        test_malloc = kmalloc(1234, GFP_KERNEL);
        if (!test_malloc)
                pr_info("failed to kmalloc\n");

        schedule_on_each_cpu(test_work);

        kfree(test_malloc);

        set_current_state(TASK_INTERRUPTIBLE);
        while (!kthread_should_stop()) {
                schedule();
                set_current_state(TASK_INTERRUPTIBLE);
        }
        __set_current_state(TASK_RUNNING);

        return 0;
}

/*
 * Do various things that may trigger events.
 */
static __init void event_test_stuff(void)
{
        struct task_struct *test_thread;

        test_thread = kthread_run(event_test_thread, NULL, "test-events");
        msleep(1);
        kthread_stop(test_thread);
}

/*
 * For every trace event defined, we will test each trace point separately,
 * and then by groups, and finally all trace points.
 */
static __init void event_trace_self_tests(void)
{
        struct ftrace_subsystem_dir *dir;
        struct ftrace_event_file *file;
        struct ftrace_event_call *call;
        struct event_subsystem *system;
        struct trace_array *tr;
        int ret;

        tr = top_trace_array();
        if (!tr)
                return;

        pr_info("Running tests on trace events:\n");

        list_for_each_entry(file, &tr->events, list) {

                call = file->event_call;

                /* Only test those that have a probe */
                if (!call->class || !call->class->probe)
                        continue;

/*
 * Testing syscall events here is pretty useless, but
 * we still do it if configured. But this is time consuming.
 * What we really need is a user thread to perform the
 * syscalls as we test.
 */
#ifndef CONFIG_EVENT_TRACE_TEST_SYSCALLS
                if (call->class->system &&
                    strcmp(call->class->system, "syscalls") == 0)
                        continue;
#endif

                pr_info("Testing event %s: ", ftrace_event_name(call));

                /*
                 * If an event is already enabled, someone is using
                 * it and the self test should not be on.
                 */
                if (file->flags & FTRACE_EVENT_FL_ENABLED) {
                        pr_warn("Enabled event during self test!\n");
                        WARN_ON_ONCE(1);
                        continue;
                }

                ftrace_event_enable_disable(file, 1);
                event_test_stuff();
                ftrace_event_enable_disable(file, 0);

                pr_cont("OK\n");
        }

        /* Now test at the sub system level */

        pr_info("Running tests on trace event systems:\n");

        list_for_each_entry(dir, &tr->systems, list) {

                system = dir->subsystem;

                /* the ftrace system is special, skip it */
                if (strcmp(system->name, "ftrace") == 0)
                        continue;

                pr_info("Testing event system %s: ", system->name);

                ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 1);
                if (WARN_ON_ONCE(ret)) {
                        pr_warn("error enabling system %s\n",
                                system->name);
                        continue;
                }

                event_test_stuff();

                ret = __ftrace_set_clr_event(tr, NULL, system->name, NULL, 0);
                if (WARN_ON_ONCE(ret)) {
                        pr_warn("error disabling system %s\n",
                                system->name);
                        continue;
                }

                pr_cont("OK\n");
        }

        /* Test with all events enabled */

        pr_info("Running tests on all trace events:\n");
        pr_info("Testing all events: ");

        ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 1);
        if (WARN_ON_ONCE(ret)) {
                pr_warn("error enabling all events\n");
                return;
        }

        event_test_stuff();

        /* reset sysname */
        ret = __ftrace_set_clr_event(tr, NULL, NULL, NULL, 0);
        if (WARN_ON_ONCE(ret)) {
                pr_warn("error disabling all events\n");
                return;
        }

        pr_cont("OK\n");
}

#ifdef CONFIG_FUNCTION_TRACER

static DEFINE_PER_CPU(atomic_t, ftrace_test_event_disable);

static void
function_test_events_call(unsigned long ip, unsigned long parent_ip,
                          struct ftrace_ops *op, struct pt_regs *pt_regs)
{
        struct ring_buffer_event *event;
        struct ring_buffer *buffer;
        struct ftrace_entry *entry;
        unsigned long flags;
        long disabled;
        int cpu;
        int pc;

        pc = preempt_count();
        preempt_disable_notrace();
        cpu = raw_smp_processor_id();
        disabled = atomic_inc_return(&per_cpu(ftrace_test_event_disable, cpu));

        if (disabled != 1)
                goto out;

        local_save_flags(flags);

        event = trace_current_buffer_lock_reserve(&buffer,
                                                  TRACE_FN, sizeof(*entry),
                                                  flags, pc);
        if (!event)
                goto out;
        entry   = ring_buffer_event_data(event);
        entry->ip                       = ip;
        entry->parent_ip                = parent_ip;

        trace_buffer_unlock_commit(buffer, event, flags, pc);

 out:
        atomic_dec(&per_cpu(ftrace_test_event_disable, cpu));
        preempt_enable_notrace();
}

static struct ftrace_ops trace_ops __initdata  =
{
        .func = function_test_events_call,
        .flags = FTRACE_OPS_FL_RECURSION_SAFE,
};

static __init void event_trace_self_test_with_function(void)
{
        int ret;
        ret = register_ftrace_function(&trace_ops);
        if (WARN_ON(ret < 0)) {
                pr_info("Failed to enable function tracer for event tests\n");
                return;
        }
        pr_info("Running tests again, along with the function tracer\n");
        event_trace_self_tests();
        unregister_ftrace_function(&trace_ops);
}
#else
static __init void event_trace_self_test_with_function(void)
{
}
#endif

static __init int event_trace_self_tests_init(void)
{
        if (!tracing_selftest_disabled) {
                event_trace_self_tests();
                event_trace_self_test_with_function();
        }

        return 0;
}

late_initcall(event_trace_self_tests_init);

#endif