tracing: Add alloc_snapshot kernel command line parameter

[mirror_ubuntu-bionic-kernel.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>.
 *
 */

#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);

#define GFP_TRACE (GFP_KERNEL | __GFP_ZERO)

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

/* 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()             \
        }

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 = kmem_cache_alloc(field_cachep, GFP_TRACE);
        if (!field)
                goto err;

        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;

err:
        kmem_cache_free(field_cachep, 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);

        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);
                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);

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

        switch (type) {
        case TRACE_REG_REGISTER:
                return tracepoint_probe_register(call->name,
                                                 call->class->probe,
                                                 file);
        case TRACE_REG_UNREGISTER:
                tracepoint_probe_unregister(call->name,
                                            call->class->probe,
                                            file);
                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_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();
                        file->flags |= FTRACE_EVENT_FL_RECORDED_CMD;
                } else {
                        tracing_stop_cmdline_record();
                        file->flags &= ~FTRACE_EVENT_FL_RECORDED_CMD;
                }
        } while_for_each_event_file();
        mutex_unlock(&event_mutex);
}

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

        switch (enable) {
        case 0:
                if (file->flags & FTRACE_EVENT_FL_ENABLED) {
                        file->flags &= ~FTRACE_EVENT_FL_ENABLED;
                        if (file->flags & FTRACE_EVENT_FL_RECORDED_CMD) {
                                tracing_stop_cmdline_record();
                                file->flags &= ~FTRACE_EVENT_FL_RECORDED_CMD;
                        }
                        call->class->reg(call, TRACE_REG_UNREGISTER, file);
                }
                break;
        case 1:
                if (!(file->flags & FTRACE_EVENT_FL_ENABLED)) {
                        if (trace_flags & TRACE_ITER_RECORD_CMD) {
                                tracing_start_cmdline_record();
                                file->flags |= FTRACE_EVENT_FL_RECORDED_CMD;
                        }
                        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", call->name);
                                break;
                        }
                        file->flags |= FTRACE_EVENT_FL_ENABLED;

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

        return ret;
}

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

        list_del(&system->list);

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

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

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(dir->subsystem->ref_count == 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);
}

/*
 * __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
 */
static int __ftrace_set_clr_event(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;
        int ret = -EINVAL;

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

                call = file->event_call;

                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(file, set);

                ret = 0;
        }
        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;

        /*
         * 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(tr, match, sub, event, set);
}

/**
 * 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();

        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", call->name);

        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 = filp->private_data;
        char *buf;

        if (file->flags & FTRACE_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_file *file = filp->private_data;
        unsigned long val;
        int ret;

        if (!file)
                return -EINVAL;

        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(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 (!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 << !!(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 = 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;
        struct ftrace_subsystem_dir *dir = NULL; /* Initialize for gcc */
        struct trace_array *tr;
        int ret;

        /* Make sure the system still exists */
        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);

        if (!system)
                return -ENODEV;

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

        ret = tracing_open_generic(inode, filp);
        if (ret < 0)
                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;

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

        dir->tr = tr;

        ret = tracing_open_generic(inode, filp);
        if (ret < 0)
                kfree(dir);

        filp->private_data = dir;

        return ret;
}

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

        /*
         * 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, 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 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, s->len);

        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 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 = 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_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_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;

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

        return ftrace_event_open(inode, file, seq_ops);
}

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;
        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:
        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 = debugfs_create_dir(name, parent);
        if (!dir->entry) {
                pr_warning("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 = debugfs_create_file("filter", 0644, dir->entry, dir,
                                    &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, 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_warning("No memory to create event subsystem %s\n",
                           name);
        return NULL;
}

static int
event_create_dir(struct dentry *parent,
                 struct ftrace_event_file *file,
                 const struct file_operations *id,
                 const struct file_operations *enable,
                 const struct file_operations *filter,
                 const struct file_operations *format)
{
        struct ftrace_event_call *call = file->event_call;
        struct trace_array *tr = file->tr;
        struct list_head *head;
        struct dentry *d_events;
        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;

        file->dir = debugfs_create_dir(call->name, d_events);
        if (!file->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, file->dir, file,
                                  enable);

#ifdef CONFIG_PERF_EVENTS
        if (call->event.type && call->class->reg)
                trace_create_file("id", 0444, file->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 -1;
                }
        }
        trace_create_file("filter", 0644, file->dir, call,
                          filter);

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

        return 0;
}

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

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

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;

                list_del(&file->list);
                debugfs_remove_recursive(file->dir);
                remove_subsystem(file->system);
                kmem_cache_free(file_cachep, 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;

        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
__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;
}

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

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

        file->event_call = call;
        file->tr = tr;
        list_add(&file->list, &tr->events);

        return event_create_dir(tr->event_dir, file, id, enable, filter, format);
}

/*
 * 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 = kmem_cache_alloc(file_cachep, GFP_TRACE);
        if (!file)
                return -ENOMEM;

        file->event_call = call;
        file->tr = tr;
        list_add(&file->list, &tr->events);

        return 0;
}

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

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

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

        mutex_unlock(&event_mutex);
        return ret;
}

/*
 * 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);
}

/* 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 *
find_ftrace_file_ops(struct ftrace_module_file_ops *file_ops, struct module *mod)
{
        /*
         * As event_calls are added in groups by module,
         * when we find one file_ops, we don't need to search for
         * each call in that module, as the rest should be the
         * same. Only search for a new one if the last one did
         * not match.
         */
        if (file_ops && mod == file_ops->mod)
                return file_ops;

        list_for_each_entry(file_ops, &ftrace_module_file_list, list) {
                if (file_ops->mod == mod)
                        return file_ops;
        }
        return NULL;
}

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) {
                __register_event(*call, mod);
                __add_event_to_tracers(*call, file_ops);
        }
}

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

        down_write(&trace_event_mutex);
        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);
                }
        }

        /* 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);
        }
        up_write(&trace_event_mutex);

        /*
         * 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(&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;
}

static int
__trace_add_new_mod_event(struct ftrace_event_call *call,
                          struct trace_array *tr,
                          struct ftrace_module_file_ops *file_ops)
{
        return __trace_add_new_event(call, tr,
                                     &file_ops->id, &file_ops->enable,
                                     &file_ops->filter, &file_ops->format);
}

#else
static inline struct ftrace_module_file_ops *
find_ftrace_file_ops(struct ftrace_module_file_ops *file_ops, struct module *mod)
{
        return NULL;
}
static inline int trace_module_notify(struct notifier_block *self,
                                      unsigned long val, void *data)
{
        return 0;
}
static inline int
__trace_add_new_mod_event(struct ftrace_event_call *call,
                          struct trace_array *tr,
                          struct ftrace_module_file_ops *file_ops)
{
        return -ENODEV;
}
#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_module_file_ops *file_ops = NULL;
        struct ftrace_event_call *call;
        int ret;

        list_for_each_entry(call, &ftrace_events, list) {
                if (call->mod) {
                        /*
                         * Directories for events by modules need to
                         * keep module ref counts when opened (as we don't
                         * want the module to disappear when reading one
                         * of these files). The file_ops keep account of
                         * the module ref count.
                         */
                        file_ops = find_ftrace_file_ops(file_ops, call->mod);
                        if (!file_ops)
                                continue; /* Warn? */
                        ret = __trace_add_new_mod_event(call, tr, file_ops);
                        if (ret < 0)
                                pr_warning("Could not create directory for event %s\n",
                                           call->name);
                        continue;
                }
                ret = __trace_add_new_event(call, tr,
                                            &ftrace_event_id_fops,
                                            &ftrace_enable_fops,
                                            &ftrace_event_filter_fops,
                                            &ftrace_event_format_fops);
                if (ret < 0)
                        pr_warning("Could not create directory for event %s\n",
                                   call->name);
        }
}

/*
 * 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 debugfs 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,
                                       &ftrace_event_id_fops,
                                       &ftrace_enable_fops,
                                       &ftrace_event_filter_fops,
                                       &ftrace_event_format_fops);
                if (ret < 0)
                        pr_warning("Could not create directory for event %s\n",
                                   file->event_call->name);
        }
}

/*
 * 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_warning("Could not create early event %s\n",
                                   call->name);
        }
}

/* 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) {
                list_del(&file->list);
                debugfs_remove_recursive(file->dir);
                remove_subsystem(file->system);
                kmem_cache_free(file_cachep, file);
        }
}

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

        list_for_each_entry(tr, &ftrace_trace_arrays, list) {
                if (file_ops)
                        __trace_add_new_mod_event(call, tr, file_ops);
                else
                        __trace_add_new_event(call, tr,
                                              &ftrace_event_id_fops,
                                              &ftrace_enable_fops,
                                              &ftrace_event_filter_fops,
                                              &ftrace_event_format_fops);
        }
}

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

        d_events = debugfs_create_dir("events", parent);
        if (!d_events) {
                pr_warning("Could not create debugfs '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_mutex);
        __trace_add_event_dirs(tr);
        up_write(&trace_event_mutex);

 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_mutex);
        __trace_early_add_event_dirs(tr);
        up_write(&trace_event_mutex);

 out_unlock:
        mutex_unlock(&event_mutex);

        return ret;
}

int event_trace_del_tracer(struct trace_array *tr)
{
        /* Disable any running events */
        __ftrace_set_clr_event(tr, NULL, NULL, NULL, 0);

        mutex_lock(&event_mutex);

        down_write(&trace_event_mutex);
        __trace_remove_event_dirs(tr);
        debugfs_remove_recursive(tr->event_dir);
        up_write(&trace_event_mutex);

        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 int event_trace_enable(void)
{
        struct trace_array *tr = top_trace_array();
        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);
        }

        /*
         * 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);

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

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

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

        trace_printk_start_comm();

        return 0;
}

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

        tr = top_trace_array();

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

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

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

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

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

        return 0;
}
early_initcall(event_trace_memsetup);
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_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();

        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: ", call->name);

                /*
                 * 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_warning("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_warning("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_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(tr, 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(tr, 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_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