trace_events.c

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/*
 * event tracer
 *
 * Copyright (C) 2008 Red Hat Inc, Steven Rostedt <[email protected]>
 *
 *  - Added format output of fields of the trace point.
 *    This was based off of work by Tom Zanussi <[email protected]>.
 *
 */

#include <linux/workqueue.h>
#include <linux/spinlock.h>
#include <linux/kthread.h>
#include <linux/debugfs.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);

DEFINE_MUTEX(event_storage_mutex);
EXPORT_SYMBOL_GPL(event_storage_mutex);

char event_storage[EVENT_STORAGE_SIZE];
EXPORT_SYMBOL_GPL(event_storage);

LIST_HEAD(ftrace_events);
LIST_HEAD(ftrace_common_fields);

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 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 = kzalloc(sizeof(*field), GFP_KERNEL);
    if (!field)
        goto err;

    field->name = kstrdup(name, GFP_KERNEL);
    if (!field->name)
        goto err;

    field->type = kstrdup(type, GFP_KERNEL);
    if (!field->type)
        goto err;

    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;

err:
    if (field)
        kfree(field->name);
    kfree(field);

    return -ENOMEM;
}

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);
    __common_field(int, padding);

    return ret;
}

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);
        kfree(field->type);
        kfree(field->name);
        kfree(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);

int ftrace_event_reg(struct ftrace_event_call *call,
             enum trace_reg type, void *data)
{
    switch (type) {
    case TRACE_REG_REGISTER:
        return tracepoint_probe_register(call->name,
                         call->class->probe,
                         call);
    case TRACE_REG_UNREGISTER:
        tracepoint_probe_unregister(call->name,
                        call->class->probe,
                        call);
        return 0;

#ifdef CONFIG_PERF_EVENTS
    case TRACE_REG_PERF_REGISTER:
        return tracepoint_probe_register(call->name,
                         call->class->perf_probe,
                         call);
    case TRACE_REG_PERF_UNREGISTER:
        tracepoint_probe_unregister(call->name,
                        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_call *call;

    mutex_lock(&event_mutex);
    list_for_each_entry(call, &ftrace_events, list) {
        if (!(call->flags & TRACE_EVENT_FL_ENABLED))
            continue;

        if (enable) {
            tracing_start_cmdline_record();
            call->flags |= TRACE_EVENT_FL_RECORDED_CMD;
        } else {
            tracing_stop_cmdline_record();
            call->flags &= ~TRACE_EVENT_FL_RECORDED_CMD;
        }
    }
    mutex_unlock(&event_mutex);
}

static int ftrace_event_enable_disable(struct ftrace_event_call *call,
                    int enable)
{
    int ret = 0;

    switch (enable) {
    case 0:
        if (call->flags & TRACE_EVENT_FL_ENABLED) {
            call->flags &= ~TRACE_EVENT_FL_ENABLED;
            if (call->flags & TRACE_EVENT_FL_RECORDED_CMD) {
                tracing_stop_cmdline_record();
                call->flags &= ~TRACE_EVENT_FL_RECORDED_CMD;
            }
            call->class->reg(call, TRACE_REG_UNREGISTER, NULL);
        }
        break;
    case 1:
        if (!(call->flags & TRACE_EVENT_FL_ENABLED)) {
            if (trace_flags & TRACE_ITER_RECORD_CMD) {
                tracing_start_cmdline_record();
                call->flags |= TRACE_EVENT_FL_RECORDED_CMD;
            }
            ret = call->class->reg(call, TRACE_REG_REGISTER, NULL);
            if (ret) {
                tracing_stop_cmdline_record();
                pr_info("event trace: Could not enable event "
                    "%s\n", call->name);
                break;
            }
            call->flags |= TRACE_EVENT_FL_ENABLED;
        }
        break;
    }

    return ret;
}

static void ftrace_clear_events(void)
{
    struct ftrace_event_call *call;

    mutex_lock(&event_mutex);
    list_for_each_entry(call, &ftrace_events, list) {
        ftrace_event_enable_disable(call, 0);
    }
    mutex_unlock(&event_mutex);
}

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

    WARN_ON_ONCE(system->ref_count == 0);
    if (--system->ref_count)
        return;

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

static void __get_system(struct event_subsystem *system)
{
    WARN_ON_ONCE(system->ref_count == 0);
    system->ref_count++;
}

static void put_system(struct event_subsystem *system)
{
    mutex_lock(&event_mutex);
    __put_system(system);
    mutex_unlock(&event_mutex);
}

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

    mutex_lock(&event_mutex);
    list_for_each_entry(call, &ftrace_events, list) {

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

        if (call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
            continue;

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

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

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

        ftrace_event_enable_disable(call, set);

        ret = 0;
    }
    mutex_unlock(&event_mutex);

    return ret;
}

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

    /*
     * 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;
    }

    return __ftrace_set_clr_event(match, sub, event, set);
}

int trace_set_clr_event(const char *system, const char *event, int set)
{
    return __ftrace_set_clr_event(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;
    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(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_call *call = v;

    (*pos)++;

    list_for_each_entry_continue(call, &ftrace_events, list) {
        /*
         * 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 call;
    }

    return NULL;
}

static void *t_start(struct seq_file *m, loff_t *pos)
{
    struct ftrace_event_call *call;
    loff_t l;

    mutex_lock(&event_mutex);

    call = list_entry(&ftrace_events, struct ftrace_event_call, list);
    for (l = 0; l <= *pos; ) {
        call = t_next(m, call, &l);
        if (!call)
            break;
    }
    return call;
}

static void *
s_next(struct seq_file *m, void *v, loff_t *pos)
{
    struct ftrace_event_call *call = v;

    (*pos)++;

    list_for_each_entry_continue(call, &ftrace_events, list) {
        if (call->flags & TRACE_EVENT_FL_ENABLED)
            return call;
    }

    return NULL;
}

static void *s_start(struct seq_file *m, loff_t *pos)
{
    struct ftrace_event_call *call;
    loff_t l;

    mutex_lock(&event_mutex);

    call = list_entry(&ftrace_events, struct ftrace_event_call, list);
    for (l = 0; l <= *pos; ) {
        call = s_next(m, call, &l);
        if (!call)
            break;
    }
    return call;
}

static int t_show(struct seq_file *m, void *v)
{
    struct ftrace_event_call *call = v;

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

    return 0;
}

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

static int
ftrace_event_seq_open(struct inode *inode, struct file *file)
{
    const struct seq_operations *seq_ops;

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

    seq_ops = inode->i_private;
    return seq_open(file, seq_ops);
}

static ssize_t
event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
          loff_t *ppos)
{
    struct ftrace_event_call *call = filp->private_data;
    char *buf;

    if (call->flags & TRACE_EVENT_FL_ENABLED)
        buf = "1\n";
    else
        buf = "0\n";

    return simple_read_from_buffer(ubuf, cnt, ppos, buf, 2);
}

static ssize_t
event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
           loff_t *ppos)
{
    struct ftrace_event_call *call = filp->private_data;
    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:
        mutex_lock(&event_mutex);
        ret = ftrace_event_enable_disable(call, 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 event_subsystem *system = filp->private_data;
    struct ftrace_event_call *call;
    char buf[2];
    int set = 0;
    int ret;

    mutex_lock(&event_mutex);
    list_for_each_entry(call, &ftrace_events, list) {
        if (!call->name || !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 << !!(call->flags & TRACE_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 event_subsystem *system = filp->private_data;
    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(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 = m->private;
    struct ftrace_event_field *field;
    struct list_head *common_head = &ftrace_common_fields;
    struct list_head *head = trace_get_fields(call);

    (*pos)++;

    switch ((unsigned long)v) {
    case FORMAT_HEADER:
        if (unlikely(list_empty(common_head)))
            return NULL;

        field = list_entry(common_head->prev,
                   struct ftrace_event_field, link);
        return field;

    case FORMAT_FIELD_SEPERATOR:
        if (unlikely(list_empty(head)))
            return NULL;

        field = list_entry(head->prev, struct ftrace_event_field, link);
        return field;

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

    field = v;
    if (field->link.prev == common_head)
        return (void *)FORMAT_FIELD_SEPERATOR;
    else if (field->link.prev == head)
        return (void *)FORMAT_PRINTFMT;

    field = list_entry(field->link.prev, struct ftrace_event_field, link);

    return field;
}

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

    /* Start by showing the header */
    if (!*pos)
        return (void *)FORMAT_HEADER;

    p = (void *)FORMAT_HEADER;
    do {
        p = f_next(m, p, &l);
    } while (p && l < *pos);

    return p;
}

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

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

    /*
     * 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_stop(struct seq_file *m, void *p)
{
}

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 ftrace_event_call *call = inode->i_private;
    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 = call;

    return 0;
}

static ssize_t
event_id_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
{
    struct ftrace_event_call *call = 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);
    trace_seq_printf(s, "%d\n", call->event.type);

    r = simple_read_from_buffer(ubuf, cnt, ppos,
                    s->buffer, s->len);
    kfree(s);
    return r;
}

static ssize_t
event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
          loff_t *ppos)
{
    struct ftrace_event_call *call = 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);

    print_event_filter(call, s);
    r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);

    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_call *call = 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_event_filter(call, buf);
    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;
    int ret;

    if (!inode->i_private)
        goto skip_search;

    /* Make sure the system still exists */
    mutex_lock(&event_mutex);
    list_for_each_entry(system, &event_subsystems, list) {
        if (system == inode->i_private) {
            /* Don't open systems with no events */
            if (!system->nr_events) {
                system = NULL;
                break;
            }
            __get_system(system);
            break;
        }
    }
    mutex_unlock(&event_mutex);

    if (system != inode->i_private)
        return -ENODEV;

 skip_search:
    ret = tracing_open_generic(inode, filp);
    if (ret < 0 && system)
        put_system(system);

    return ret;
}

static int subsystem_release(struct inode *inode, struct file *file)
{
    struct event_subsystem *system = inode->i_private;

    if (system)
        put_system(system);

    return 0;
}

static ssize_t
subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
              loff_t *ppos)
{
    struct event_subsystem *system = 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);

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

    kfree(s);

    return r;
}

static ssize_t
subsystem_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
               loff_t *ppos)
{
    struct event_subsystem *system = 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(system, 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, s->len);

    kfree(s);

    return r;
}

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_seq_open,
    .read = seq_read,
    .llseek = seq_lseek,
    .release = seq_release,
};

static const struct file_operations ftrace_set_event_fops = {
    .open = ftrace_event_seq_open,
    .read = seq_read,
    .write = ftrace_event_write,
    .llseek = seq_lseek,
    .release = seq_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 = {
    .open = tracing_open_generic,
    .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_show_header_fops = {
    .open = tracing_open_generic,
    .read = show_header,
    .llseek = default_llseek,
};

static struct dentry *event_trace_events_dir(void)
{
    static struct dentry *d_tracer;
    static struct dentry *d_events;

    if (d_events)
        return d_events;

    d_tracer = tracing_init_dentry();
    if (!d_tracer)
        return NULL;

    d_events = debugfs_create_dir("events", d_tracer);
    if (!d_events)
        pr_warning("Could not create debugfs "
               "'events' directory\n");

    return d_events;
}

static struct dentry *
event_subsystem_dir(const char *name, struct dentry *d_events)
{
    struct event_subsystem *system;
    struct dentry *entry;

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

    /* need to create new entry */
    system = kmalloc(sizeof(*system), GFP_KERNEL);
    if (!system) {
        pr_warning("No memory to create event subsystem %s\n",
               name);
        return d_events;
    }

    system->entry = debugfs_create_dir(name, d_events);
    if (!system->entry) {
        pr_warning("Could not create event subsystem %s\n",
               name);
        kfree(system);
        return d_events;
    }

    system->nr_events = 1;
    system->ref_count = 1;
    system->name = kstrdup(name, GFP_KERNEL);
    if (!system->name) {
        debugfs_remove(system->entry);
        kfree(system);
        return d_events;
    }

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

    system->filter = NULL;

    system->filter = kzalloc(sizeof(struct event_filter), GFP_KERNEL);
    if (!system->filter) {
        pr_warning("Could not allocate filter for subsystem "
               "'%s'\n", name);
        return system->entry;
    }

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

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

    return system->entry;
}

static int
event_create_dir(struct ftrace_event_call *call, struct dentry *d_events,
         const struct file_operations *id,
         const struct file_operations *enable,
         const struct file_operations *filter,
         const struct file_operations *format)
{
    struct list_head *head;
    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(call->class->system, d_events);

    call->dir = debugfs_create_dir(call->name, d_events);
    if (!call->dir) {
        pr_warning("Could not create debugfs "
               "'%s' directory\n", call->name);
        return -1;
    }

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

#ifdef CONFIG_PERF_EVENTS
    if (call->event.type && call->class->reg)
        trace_create_file("id", 0444, call->dir, call,
                  id);
#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_warning("Could not initialize trace point"
                   " events/%s\n", call->name);
            return ret;
        }
    }
    trace_create_file("filter", 0644, call->dir, call,
              filter);

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

    return 0;
}

static void event_remove(struct ftrace_event_call *call)
{
    ftrace_event_enable_disable(call, 0);
    if (call->event.funcs)
        __unregister_ftrace_event(&call->event);
    list_del(&call->list);
}

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

    if (WARN_ON(!call->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",
                call->name);
    }

    return ret;
}

static int
__trace_add_event_call(struct ftrace_event_call *call, struct module *mod,
               const struct file_operations *id,
               const struct file_operations *enable,
               const struct file_operations *filter,
               const struct file_operations *format)
{
    struct dentry *d_events;
    int ret;

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

    d_events = event_trace_events_dir();
    if (!d_events)
        return -ENOENT;

    ret = event_create_dir(call, d_events, id, enable, filter, format);
    if (!ret)
        list_add(&call->list, &ftrace_events);
    call->mod = mod;

    return ret;
}

/* Add an additional event_call dynamically */
int trace_add_event_call(struct ftrace_event_call *call)
{
    int ret;
    mutex_lock(&event_mutex);
    ret = __trace_add_event_call(call, NULL, &ftrace_event_id_fops,
                     &ftrace_enable_fops,
                     &ftrace_event_filter_fops,
                     &ftrace_event_format_fops);
    mutex_unlock(&event_mutex);
    return ret;
}

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

    if (strcmp(name, TRACE_SYSTEM) == 0)
        return;

    list_for_each_entry(system, &event_subsystems, list) {
        if (strcmp(system->name, name) == 0) {
            if (!--system->nr_events) {
                debugfs_remove_recursive(system->entry);
                list_del(&system->list);
                __put_system(system);
            }
            break;
        }
    }
}

/*
 * Must be called under locking both of event_mutex and trace_event_mutex.
 */
static void __trace_remove_event_call(struct ftrace_event_call *call)
{
    event_remove(call);
    trace_destroy_fields(call);
    destroy_preds(call);
    debugfs_remove_recursive(call->dir);
    remove_subsystem_dir(call->class->system);
}

/* Remove an event_call */
void trace_remove_event_call(struct ftrace_event_call *call)
{
    mutex_lock(&event_mutex);
    down_write(&trace_event_mutex);
    __trace_remove_event_call(call);
    up_write(&trace_event_mutex);
    mutex_unlock(&event_mutex);
}

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

#ifdef CONFIG_MODULES

static LIST_HEAD(ftrace_module_file_list);

/*
 * Modules must own their file_operations to keep up with
 * reference counting.
 */
struct ftrace_module_file_ops {
    struct list_head        list;
    struct module           *mod;
    struct file_operations      id;
    struct file_operations      enable;
    struct file_operations      format;
    struct file_operations      filter;
};

static struct ftrace_module_file_ops *
trace_create_file_ops(struct module *mod)
{
    struct ftrace_module_file_ops *file_ops;

    /*
     * This is a bit of a PITA. To allow for correct reference
     * counting, modules must "own" their file_operations.
     * To do this, we allocate the file operations that will be
     * used in the event directory.
     */

    file_ops = kmalloc(sizeof(*file_ops), GFP_KERNEL);
    if (!file_ops)
        return NULL;

    file_ops->mod = mod;

    file_ops->id = ftrace_event_id_fops;
    file_ops->id.owner = mod;

    file_ops->enable = ftrace_enable_fops;
    file_ops->enable.owner = mod;

    file_ops->filter = ftrace_event_filter_fops;
    file_ops->filter.owner = mod;

    file_ops->format = ftrace_event_format_fops;
    file_ops->format.owner = mod;

    list_add(&file_ops->list, &ftrace_module_file_list);

    return file_ops;
}

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

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

    if (start == end)
        return;

    file_ops = trace_create_file_ops(mod);
    if (!file_ops)
        return;

    for_each_event(call, start, end) {
        __trace_add_event_call(*call, mod,
                       &file_ops->id, &file_ops->enable,
                       &file_ops->filter, &file_ops->format);
    }
}

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

    down_write(&trace_event_mutex);
    list_for_each_entry_safe(call, p, &ftrace_events, list) {
        if (call->mod == mod) {
            found = true;
            __trace_remove_event_call(call);
        }
    }

    /* Now free the file_operations */
    list_for_each_entry(file_ops, &ftrace_module_file_list, list) {
        if (file_ops->mod == mod)
            break;
    }
    if (&file_ops->list != &ftrace_module_file_list) {
        list_del(&file_ops->list);
        kfree(file_ops);
    }

    /*
     * It is safest to reset the ring buffer if the module being unloaded
     * registered any events.
     */
    if (found)
        tracing_reset_current_online_cpus();
    up_write(&trace_event_mutex);
}

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

    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);

    return 0;
}
#else
static int trace_module_notify(struct notifier_block *self,
                   unsigned long val, void *data)
{
    return 0;
}
#endif /* CONFIG_MODULES */

static struct notifier_block trace_module_nb = {
    .notifier_call = trace_module_notify,
    .priority = 0,
};

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 = 1;
    tracing_selftest_disabled = 1;

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

static __init int event_trace_enable(void)
{
    struct ftrace_event_call **iter, *call;
    char *buf = bootup_event_buf;
    char *token;
    int ret;

    for_each_event(iter, __start_ftrace_events, __stop_ftrace_events) {

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

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

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

        ret = ftrace_set_clr_event(token, 1);
        if (ret)
            pr_warn("Failed to enable trace event: %s\n", token);
    }
    return 0;
}

static __init int event_trace_init(void)
{
    struct ftrace_event_call *call;
    struct dentry *d_tracer;
    struct dentry *entry;
    struct dentry *d_events;
    int ret;

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

    entry = debugfs_create_file("available_events", 0444, d_tracer,
                    (void *)&show_event_seq_ops,
                    &ftrace_avail_fops);
    if (!entry)
        pr_warning("Could not create debugfs "
               "'available_events' entry\n");

    entry = debugfs_create_file("set_event", 0644, d_tracer,
                    (void *)&show_set_event_seq_ops,
                    &ftrace_set_event_fops);
    if (!entry)
        pr_warning("Could not create debugfs "
               "'set_event' entry\n");

    d_events = event_trace_events_dir();
    if (!d_events)
        return 0;

    /* 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,
              NULL, &ftrace_system_enable_fops);

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

    /*
     * Early initialization already enabled ftrace event.
     * Now it's only necessary to create the event directory.
     */
    list_for_each_entry(call, &ftrace_events, list) {

        ret = event_create_dir(call, d_events,
                       &ftrace_event_id_fops,
                       &ftrace_enable_fops,
                       &ftrace_event_filter_fops,
                       &ftrace_event_format_fops);
        if (ret < 0)
            event_remove(call);
    }

    ret = register_module_notifier(&trace_module_nb);
    if (ret)
        pr_warning("Failed to register trace events module notifier\n");

    return 0;
}
core_initcall(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();

    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_event_call *call;
    struct event_subsystem *system;
    int ret;

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

    list_for_each_entry(call, &ftrace_events, list) {

        /* 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: ", call->name);

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

        ftrace_event_enable_disable(call, 1);
        event_test_stuff();
        ftrace_event_enable_disable(call, 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(system, &event_subsystems, list) {

        /* 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(NULL, system->name, NULL, 1);
        if (WARN_ON_ONCE(ret)) {
            pr_warning("error enabling system %s\n",
                   system->name);
            continue;
        }

        event_test_stuff();

        ret = __ftrace_set_clr_event(NULL, system->name, NULL, 0);
        if (WARN_ON_ONCE(ret)) {
            pr_warning("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(NULL, NULL, NULL, 1);
    if (WARN_ON_ONCE(ret)) {
        pr_warning("error enabling all events\n");
        return;
    }

    event_test_stuff();

    /* reset sysname */
    ret = __ftrace_set_clr_event(NULL, NULL, NULL, 0);
    if (WARN_ON_ONCE(ret)) {
        pr_warning("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_nowake_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