// SPDX-License-Identifier: GPL-2.0
/*
 * event tracer
 *
 * Copyright (C) 2008 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
 *
 *  - Added format output of fields of the trace point.
 *    This was based off of work by Tom Zanussi <tzanussi@gmail.com>.
 *
 */

#define pr_fmt(fmt) fmt

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

#include <trace/events/sched.h>
#include <trace/syscall.h>

#include <asm/setup.h>

#include "trace_output.h"

#undef TRACE_SYSTEM
#define TRACE_SYSTEM "TRACE_SYSTEM"

DEFINE_MUTEX(event_mutex);

LIST_HEAD(ftrace_events);
static LIST_HEAD(ftrace_generic_fields);
static LIST_HEAD(ftrace_common_fields);
static bool eventdir_initialized;

static LIST_HEAD(module_strings);

struct module_string {
        struct list_head        next;
        struct module           *module;
        char                    *str;
};

#define GFP_TRACE (GFP_KERNEL | __GFP_ZERO)

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

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

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

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

/* 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 trace_event_file *___n;                          \
                list_for_each_entry_safe(file, ___n, &tr->events, list)

#define while_for_each_event_file()             \
        }

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

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

        return NULL;
}

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

        head = trace_get_fields(call);
        field = __find_event_field(head, name);
        if (field)
                return field;

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

        return __find_event_field(&ftrace_common_fields, name);
}

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

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

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

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

        field->offset = offset;
        field->size = size;
        field->is_signed = is_signed;
        field->needs_test = need_test;
        field->len = len;

        list_add(&field->link, head);

        return 0;
}

int trace_define_field(struct trace_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, 0, 0);
}
EXPORT_SYMBOL_GPL(trace_define_field);

static int trace_define_field_ext(struct trace_event_call *call, const char *type,
                       const char *name, int offset, int size, int is_signed,
                       int filter_type, int len, int need_test)
{
        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, len, need_test);
}

#define __generic_field(type, item, filter_type)                        \
        ret = __trace_define_field(&ftrace_generic_fields, #type,       \
                                   #item, 0, 0, is_signed_type(type),   \
                                   filter_type, 0, 0);                  \
        if (ret)                                                        \
                return ret;

#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,  \
                                   0, 0);                               \
        if (ret)                                                        \
                return ret;

static int trace_define_generic_fields(void)
{
        int ret;

        __generic_field(int, CPU, FILTER_CPU);
        __generic_field(int, cpu, FILTER_CPU);
        __generic_field(int, common_cpu, FILTER_CPU);
        __generic_field(char *, COMM, FILTER_COMM);
        __generic_field(char *, comm, FILTER_COMM);
        __generic_field(char *, stacktrace, FILTER_STACKTRACE);
        __generic_field(char *, STACKTRACE, FILTER_STACKTRACE);

        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);
        /* Holds both preempt_count and migrate_disable */
        __common_field(unsigned char, preempt_count);
        __common_field(int, pid);

        return ret;
}

static void trace_destroy_fields(struct trace_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);
        }
}

/*
 * run-time version of trace_event_get_offsets_<call>() that returns the last
 * accessible offset of trace fields excluding __dynamic_array bytes
 */
int trace_event_get_offsets(struct trace_event_call *call)
{
        struct ftrace_event_field *tail;
        struct list_head *head;

        head = trace_get_fields(call);
        /*
         * head->next points to the last field with the largest offset,
         * since it was added last by trace_define_field()
         */
        tail = list_first_entry(head, struct ftrace_event_field, link);
        return tail->offset + tail->size;
}


static struct trace_event_fields *find_event_field(const char *fmt,
                                                   struct trace_event_call *call)
{
        struct trace_event_fields *field = call->class->fields_array;
        const char *p = fmt;
        int len;

        if (!(len = str_has_prefix(fmt, "REC->")))
                return NULL;
        fmt += len;
        for (p = fmt; *p; p++) {
                if (!isalnum(*p) && *p != '_')
                        break;
        }
        len = p - fmt;

        for (; field->type; field++) {
                if (strncmp(field->name, fmt, len) || field->name[len])
                        continue;

                return field;
        }
        return NULL;
}

/*
 * Check if the referenced field is an array and return true,
 * as arrays are OK to dereference.
 */
static bool test_field(const char *fmt, struct trace_event_call *call)
{
        struct trace_event_fields *field;

        field = find_event_field(fmt, call);
        if (!field)
                return false;

        /* This is an array and is OK to dereference. */
        return strchr(field->type, '[') != NULL;
}

/* Look for a string within an argument */
static bool find_print_string(const char *arg, const char *str, const char *end)
{
        const char *r;

        r = strstr(arg, str);
        return r && r < end;
}

/* Return true if the argument pointer is safe */
static bool process_pointer(const char *fmt, int len, struct trace_event_call *call)
{
        const char *r, *e, *a;

        e = fmt + len;

        /* Find the REC-> in the argument */
        r = strstr(fmt, "REC->");
        if (r && r < e) {
                /*
                 * Addresses of events on the buffer, or an array on the buffer is
                 * OK to dereference. There's ways to fool this, but
                 * this is to catch common mistakes, not malicious code.
                 */
                a = strchr(fmt, '&');
                if ((a && (a < r)) || test_field(r, call))
                        return true;
        } else if (find_print_string(fmt, "__get_dynamic_array(", e)) {
                return true;
        } else if (find_print_string(fmt, "__get_rel_dynamic_array(", e)) {
                return true;
        } else if (find_print_string(fmt, "__get_dynamic_array_len(", e)) {
                return true;
        } else if (find_print_string(fmt, "__get_rel_dynamic_array_len(", e)) {
                return true;
        } else if (find_print_string(fmt, "__get_sockaddr(", e)) {
                return true;
        } else if (find_print_string(fmt, "__get_rel_sockaddr(", e)) {
                return true;
        }
        return false;
}

/* Return true if the string is safe */
static bool process_string(const char *fmt, int len, struct trace_event_call *call)
{
        struct trace_event_fields *field;
        const char *r, *e, *s;

        e = fmt + len;

        /*
         * There are several helper functions that return strings.
         * If the argument contains a function, then assume its field is valid.
         * It is considered that the argument has a function if it has:
         *   alphanumeric or '_' before a parenthesis.
         */
        s = fmt;
        do {
                r = strstr(s, "(");
                if (!r || r >= e)
                        break;
                for (int i = 1; r - i >= s; i++) {
                        char ch = *(r - i);
                        if (isspace(ch))
                                continue;
                        if (isalnum(ch) || ch == '_')
                                return true;
                        /* Anything else, this isn't a function */
                        break;
                }
                /* A function could be wrapped in parenthesis, try the next one */
                s = r + 1;
        } while (s < e);

        /*
         * Check for arrays. If the argument has: foo[REC->val]
         * then it is very likely that foo is an array of strings
         * that are safe to use.
         */
        r = strstr(s, "[");
        if (r && r < e) {
                r = strstr(r, "REC->");
                if (r && r < e)
                        return true;
        }

        /*
         * If there's any strings in the argument consider this arg OK as it
         * could be: REC->field ? "foo" : "bar" and we don't want to get into
         * verifying that logic here.
         */
        if (find_print_string(fmt, "\"", e))
                return true;

        /* Dereferenced strings are also valid like any other pointer */
        if (process_pointer(fmt, len, call))
                return true;

        /* Make sure the field is found */
        field = find_event_field(fmt, call);
        if (!field)
                return false;

        /* Test this field's string before printing the event */
        call->flags |= TRACE_EVENT_FL_TEST_STR;
        field->needs_test = 1;

        return true;
}

static void handle_dereference_arg(const char *arg_str, u64 string_flags, int len,
                                   u64 *dereference_flags, int arg,
                                   struct trace_event_call *call)
{
        if (string_flags & (1ULL << arg)) {
                if (process_string(arg_str, len, call))
                        *dereference_flags &= ~(1ULL << arg);
        } else if (process_pointer(arg_str, len, call))
                *dereference_flags &= ~(1ULL << arg);
        else
                pr_warn("TRACE EVENT ERROR: Bad dereference argument: '%.*s'\n",
                        len, arg_str);
}

/*
 * Examine the print fmt of the event looking for unsafe dereference
 * pointers using %p* that could be recorded in the trace event and
 * much later referenced after the pointer was freed. Dereferencing
 * pointers are OK, if it is dereferenced into the event itself.
 */
static void test_event_printk(struct trace_event_call *call)
{
        u64 dereference_flags = 0;
        u64 string_flags = 0;
        bool first = true;
        const char *fmt;
        int parens = 0;
        char in_quote = 0;
        int start_arg = 0;
        int arg = 0;
        int i, e;

        fmt = call->print_fmt;

        if (!fmt)
                return;

        for (i = 0; fmt[i]; i++) {
                switch (fmt[i]) {
                case '\\':
                        i++;
                        if (!fmt[i])
                                return;
                        continue;
                case '"':
                case '\'':
                        /*
                         * The print fmt starts with a string that
                         * is processed first to find %p* usage,
                         * then after the first string, the print fmt
                         * contains arguments that are used to check
                         * if the dereferenced %p* usage is safe.
                         */
                        if (first) {
                                if (fmt[i] == '\'')
                                        continue;
                                if (in_quote) {
                                        arg = 0;
                                        first = false;
                                        /*
                                         * If there was no %p* uses
                                         * the fmt is OK.
                                         */
                                        if (!dereference_flags)
                                                return;
                                }
                        }
                        if (in_quote) {
                                if (in_quote == fmt[i])
                                        in_quote = 0;
                        } else {
                                in_quote = fmt[i];
                        }
                        continue;
                case '%':
                        if (!first || !in_quote)
                                continue;
                        i++;
                        if (!fmt[i])
                                return;
                        switch (fmt[i]) {
                        case '%':
                                continue;
                        case 'p':
 do_pointer:
                                /* Find dereferencing fields */
                                switch (fmt[i + 1]) {
                                case 'B': case 'R': case 'r':
                                case 'b': case 'M': case 'm':
                                case 'I': case 'i': case 'E':
                                case 'U': case 'V': case 'N':
                                case 'a': case 'd': case 'D':
                                case 'g': case 't': case 'C':
                                case 'O': case 'f':
                                        if (WARN_ONCE(arg == 63,
                                                      "Too many args for event: %s",
                                                      trace_event_name(call)))
                                                return;
                                        dereference_flags |= 1ULL << arg;
                                }
                                break;
                        default:
                        {
                                bool star = false;
                                int j;

                                /* Increment arg if %*s exists. */
                                for (j = 0; fmt[i + j]; j++) {
                                        if (isdigit(fmt[i + j]) ||
                                            fmt[i + j] == '.')
                                                continue;
                                        if (fmt[i + j] == '*') {
                                                star = true;
                                                /* Handle %*pbl case */
                                                if (!j && fmt[i + 1] == 'p') {
                                                        arg++;
                                                        i++;
                                                        goto do_pointer;
                                                }
                                                continue;
                                        }
                                        if ((fmt[i + j] == 's')) {
                                                if (star)
                                                        arg++;
                                                if (WARN_ONCE(arg == 63,
                                                              "Too many args for event: %s",
                                                              trace_event_name(call)))
                                                        return;
                                                dereference_flags |= 1ULL << arg;
                                                string_flags |= 1ULL << arg;
                                        }
                                        break;
                                }
                                break;
                        } /* default */

                        } /* switch */
                        arg++;
                        continue;
                case '(':
                        if (in_quote)
                                continue;
                        parens++;
                        continue;
                case ')':
                        if (in_quote)
                                continue;
                        parens--;
                        if (WARN_ONCE(parens < 0,
                                      "Paren mismatch for event: %s\narg='%s'\n%*s",
                                      trace_event_name(call),
                                      fmt + start_arg,
                                      (i - start_arg) + 5, "^"))
                                return;
                        continue;
                case ',':
                        if (in_quote || parens)
                                continue;
                        e = i;
                        i++;
                        while (isspace(fmt[i]))
                                i++;

                        /*
                         * If start_arg is zero, then this is the start of the
                         * first argument. The processing of the argument happens
                         * when the end of the argument is found, as it needs to
                         * handle parenthesis and such.
                         */
                        if (!start_arg) {
                                start_arg = i;
                                /* Balance out the i++ in the for loop */
                                i--;
                                continue;
                        }

                        if (dereference_flags & (1ULL << arg)) {
                                handle_dereference_arg(fmt + start_arg, string_flags,
                                                       e - start_arg,
                                                       &dereference_flags, arg, call);
                        }

                        start_arg = i;
                        arg++;
                        /* Balance out the i++ in the for loop */
                        i--;
                }
        }

        if (dereference_flags & (1ULL << arg)) {
                handle_dereference_arg(fmt + start_arg, string_flags,
                                       i - start_arg,
                                       &dereference_flags, arg, call);
        }

        /*
         * If you triggered the below warning, the trace event reported
         * uses an unsafe dereference pointer %p*. As the data stored
         * at the trace event time may no longer exist when the trace
         * event is printed, dereferencing to the original source is
         * unsafe. The source of the dereference must be copied into the
         * event itself, and the dereference must access the copy instead.
         */
        if (WARN_ON_ONCE(dereference_flags)) {
                arg = 1;
                while (!(dereference_flags & 1)) {
                        dereference_flags >>= 1;
                        arg++;
                }
                pr_warn("event %s has unsafe dereference of argument %d\n",
                        trace_event_name(call), arg);
                pr_warn("print_fmt: %s\n", fmt);
        }
}

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

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

        test_event_printk(call);

        return 0;
}
EXPORT_SYMBOL_GPL(trace_event_raw_init);

bool trace_event_ignore_this_pid(struct trace_event_file *trace_file)
{
        struct trace_array *tr = trace_file->tr;
        struct trace_pid_list *no_pid_list;
        struct trace_pid_list *pid_list;

        pid_list = rcu_dereference_raw(tr->filtered_pids);
        no_pid_list = rcu_dereference_raw(tr->filtered_no_pids);

        if (!pid_list && !no_pid_list)
                return false;

        /*
         * This is recorded at every sched_switch for this task.
         * Thus, even if the task migrates the ignore value will be the same.
         */
        return this_cpu_read(tr->array_buffer.data->ignore_pid) != 0;
}
EXPORT_SYMBOL_GPL(trace_event_ignore_this_pid);

/**
 * trace_event_buffer_reserve - reserve space on the ring buffer for an event
 * @fbuffer: information about how to save the event
 * @trace_file: the instance file descriptor for the event
 * @len: The length of the event
 *
 * The @fbuffer has information about the ring buffer and data will
 * be added to it to be used by the call to trace_event_buffer_commit().
 * The @trace_file is the desrciptor with information about the status
 * of the given event for a specific trace_array instance.
 * The @len is the length of data to save for the event.
 *
 * Returns a pointer to the data on the ring buffer or NULL if the
 *   event was not reserved (event was filtered, too big, or the buffer
 *   simply was disabled for write).
 */
void *trace_event_buffer_reserve(struct trace_event_buffer *fbuffer,
                                 struct trace_event_file *trace_file,
                                 unsigned long len)
{
        struct trace_event_call *event_call = trace_file->event_call;

        if ((trace_file->flags & EVENT_FILE_FL_PID_FILTER) &&
            trace_event_ignore_this_pid(trace_file))
                return NULL;

        /*
         * If CONFIG_PREEMPTION is enabled, then the tracepoint itself disables
         * preemption (adding one to the preempt_count). Since we are
         * interested in the preempt_count at the time the tracepoint was
         * hit, we need to subtract one to offset the increment.
         */
        fbuffer->trace_ctx = tracing_gen_ctx_dec();
        fbuffer->trace_file = trace_file;

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

        fbuffer->regs = NULL;
        fbuffer->entry = ring_buffer_event_data(fbuffer->event);
        return fbuffer->entry;
}
EXPORT_SYMBOL_GPL(trace_event_buffer_reserve);

int trace_event_reg(struct trace_event_call *call,
                    enum trace_reg type, void *data)
{
        struct trace_event_file *file = data;

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

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

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

        lockdep_assert_held(&event_mutex);

        do_for_each_event_file(tr, file) {

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

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

void trace_event_enable_tgid_record(bool enable)
{
        struct trace_event_file *file;
        struct trace_array *tr;

        lockdep_assert_held(&event_mutex);

        do_for_each_event_file(tr, file) {
                if (!(file->flags & EVENT_FILE_FL_ENABLED))
                        continue;

                if (enable) {
                        tracing_start_tgid_record();
                        set_bit(EVENT_FILE_FL_RECORDED_TGID_BIT, &file->flags);
                } else {
                        tracing_stop_tgid_record();
                        clear_bit(EVENT_FILE_FL_RECORDED_TGID_BIT,
                                  &file->flags);
                }
        } while_for_each_event_file();
}

static int __ftrace_event_enable_disable(struct trace_event_file *file,
                                         int enable, int soft_disable)
{
        struct trace_event_call *call = file->event_call;
        struct trace_array *tr = file->tr;
        bool soft_mode = atomic_read(&file->sm_ref) != 0;
        int ret = 0;
        int disable;

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

                if (disable && (file->flags & EVENT_FILE_FL_ENABLED)) {
                        clear_bit(EVENT_FILE_FL_ENABLED_BIT, &file->flags);
                        if (file->flags & EVENT_FILE_FL_RECORDED_CMD) {
                                tracing_stop_cmdline_record();
                                clear_bit(EVENT_FILE_FL_RECORDED_CMD_BIT, &file->flags);
                        }

                        if (file->flags & EVENT_FILE_FL_RECORDED_TGID) {
                                tracing_stop_tgid_record();
                                clear_bit(EVENT_FILE_FL_RECORDED_TGID_BIT, &file->flags);
                        }

                        ret = call->class->reg(call, TRACE_REG_UNREGISTER, file);

                        WARN_ON_ONCE(ret);
                }
                /* If in soft mode, just set the SOFT_DISABLE_BIT, else clear it */
                if (soft_mode)
                        set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags);
                else
                        clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags);
                break;
        case 1:
                /*
                 * When soft_disable is set and enable is set, we want to
                 * register the tracepoint for the event, but leave the event
                 * as is. That means, if the event was already enabled, we do
                 * nothing. If the event is disabled, we set SOFT_DISABLED
                 * before enabling the event tracepoint, so it still seems
                 * to be disabled.
                 */
                if (!soft_disable)
                        clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags);
                else {
                        if (atomic_inc_return(&file->sm_ref) > 1)
                                break;
                        /* Enable use of trace_buffered_event */
                        trace_buffered_event_enable();
                }

                if (!(file->flags & EVENT_FILE_FL_ENABLED)) {
                        bool cmd = false, tgid = false;

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

                        if (tr->trace_flags & TRACE_ITER(RECORD_CMD)) {
                                cmd = true;
                                tracing_start_cmdline_record();
                                set_bit(EVENT_FILE_FL_RECORDED_CMD_BIT, &file->flags);
                        }

                        if (tr->trace_flags & TRACE_ITER(RECORD_TGID)) {
                                tgid = true;
                                tracing_start_tgid_record();
                                set_bit(EVENT_FILE_FL_RECORDED_TGID_BIT, &file->flags);
                        }

                        ret = call->class->reg(call, TRACE_REG_REGISTER, file);
                        if (ret) {
                                if (cmd)
                                        tracing_stop_cmdline_record();
                                if (tgid)
                                        tracing_stop_tgid_record();
                                pr_info("event trace: Could not enable event "
                                        "%s\n", trace_event_name(call));
                                break;
                        }
                        set_bit(EVENT_FILE_FL_ENABLED_BIT, &file->flags);

                        /* WAS_ENABLED gets set but never cleared. */
                        set_bit(EVENT_FILE_FL_WAS_ENABLED_BIT, &file->flags);
                }
                break;
        }

        return ret;
}

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

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

#ifdef CONFIG_MODULES
struct event_mod_load {
        struct list_head        list;
        char                    *module;
        char                    *match;
        char                    *system;
        char                    *event;
};

static void free_event_mod(struct event_mod_load *event_mod)
{
        list_del(&event_mod->list);
        kfree(event_mod->module);
        kfree(event_mod->match);
        kfree(event_mod->system);
        kfree(event_mod->event);
        kfree(event_mod);
}

static void clear_mod_events(struct trace_array *tr)
{
        struct event_mod_load *event_mod, *n;

        list_for_each_entry_safe(event_mod, n, &tr->mod_events, list) {
                free_event_mod(event_mod);
        }
}

static int remove_cache_mod(struct trace_array *tr, const char *mod,
                            const char *match, const char *system, const char *event)
{
        struct event_mod_load *event_mod, *n;
        int ret = -EINVAL;

        list_for_each_entry_safe(event_mod, n, &tr->mod_events, list) {
                if (strcmp(event_mod->module, mod) != 0)
                        continue;

                if (match && strcmp(event_mod->match, match) != 0)
                        continue;

                if (system &&
                    (!event_mod->system || strcmp(event_mod->system, system) != 0))
                        continue;

                if (event &&
                    (!event_mod->event || strcmp(event_mod->event, event) != 0))
                        continue;

                free_event_mod(event_mod);
                ret = 0;
        }

        return ret;
}

static int cache_mod(struct trace_array *tr, const char *mod, int set,
                     const char *match, const char *system, const char *event)
{
        struct event_mod_load *event_mod;

        /* If the module exists, then this just failed to find an event */
        if (module_exists(mod))
                return -EINVAL;

        /* See if this is to remove a cached filter */
        if (!set)
                return remove_cache_mod(tr, mod, match, system, event);

        event_mod = kzalloc_obj(*event_mod);
        if (!event_mod)
                return -ENOMEM;

        INIT_LIST_HEAD(&event_mod->list);
        event_mod->module = kstrdup(mod, GFP_KERNEL);
        if (!event_mod->module)
                goto out_free;

        if (match) {
                event_mod->match = kstrdup(match, GFP_KERNEL);
                if (!event_mod->match)
                        goto out_free;
        }

        if (system) {
                event_mod->system = kstrdup(system, GFP_KERNEL);
                if (!event_mod->system)
                        goto out_free;
        }

        if (event) {
                event_mod->event = kstrdup(event, GFP_KERNEL);
                if (!event_mod->event)
                        goto out_free;
        }

        list_add(&event_mod->list, &tr->mod_events);

        return 0;

 out_free:
        free_event_mod(event_mod);

        return -ENOMEM;
}
#else /* CONFIG_MODULES */
static inline void clear_mod_events(struct trace_array *tr) { }
static int cache_mod(struct trace_array *tr, const char *mod, int set,
                     const char *match, const char *system, const char *event)
{
        return -EINVAL;
}
#endif

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

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

static void
event_filter_pid_sched_process_exit(void *data, struct task_struct *task)
{
        struct trace_pid_list *pid_list;
        struct trace_array *tr = data;

        guard(preempt)();
        pid_list = rcu_dereference_raw(tr->filtered_pids);
        trace_filter_add_remove_task(pid_list, NULL, task);

        pid_list = rcu_dereference_raw(tr->filtered_no_pids);
        trace_filter_add_remove_task(pid_list, NULL, task);
}

static void
event_filter_pid_sched_process_fork(void *data,
                                    struct task_struct *self,
                                    struct task_struct *task)
{
        struct trace_pid_list *pid_list;
        struct trace_array *tr = data;

        guard(preempt)();
        pid_list = rcu_dereference_sched(tr->filtered_pids);
        trace_filter_add_remove_task(pid_list, self, task);

        pid_list = rcu_dereference_sched(tr->filtered_no_pids);
        trace_filter_add_remove_task(pid_list, self, task);
}

void trace_event_follow_fork(struct trace_array *tr, bool enable)
{
        if (enable) {
                register_trace_prio_sched_process_fork(event_filter_pid_sched_process_fork,
                                                       tr, INT_MIN);
                register_trace_prio_sched_process_free(event_filter_pid_sched_process_exit,
                                                       tr, INT_MAX);
        } else {
                unregister_trace_sched_process_fork(event_filter_pid_sched_process_fork,
                                                    tr);
                unregister_trace_sched_process_free(event_filter_pid_sched_process_exit,
                                                    tr);
        }
}

static void
event_filter_pid_sched_switch_probe_pre(void *data, bool preempt,
                                        struct task_struct *prev,
                                        struct task_struct *next,
                                        unsigned int prev_state)
{
        struct trace_array *tr = data;
        struct trace_pid_list *no_pid_list;
        struct trace_pid_list *pid_list;
        bool ret;

        pid_list = rcu_dereference_sched(tr->filtered_pids);
        no_pid_list = rcu_dereference_sched(tr->filtered_no_pids);

        /*
         * Sched switch is funny, as we only want to ignore it
         * in the notrace case if both prev and next should be ignored.
         */
        ret = trace_ignore_this_task(NULL, no_pid_list, prev) &&
                trace_ignore_this_task(NULL, no_pid_list, next);

        this_cpu_write(tr->array_buffer.data->ignore_pid, ret ||
                       (trace_ignore_this_task(pid_list, NULL, prev) &&
                        trace_ignore_this_task(pid_list, NULL, next)));
}

static void
event_filter_pid_sched_switch_probe_post(void *data, bool preempt,
                                         struct task_struct *prev,
                                         struct task_struct *next,
                                         unsigned int prev_state)
{
        struct trace_array *tr = data;
        struct trace_pid_list *no_pid_list;
        struct trace_pid_list *pid_list;

        pid_list = rcu_dereference_sched(tr->filtered_pids);
        no_pid_list = rcu_dereference_sched(tr->filtered_no_pids);

        this_cpu_write(tr->array_buffer.data->ignore_pid,
                       trace_ignore_this_task(pid_list, no_pid_list, next));
}

static void
event_filter_pid_sched_wakeup_probe_pre(void *data, struct task_struct *task)
{
        struct trace_array *tr = data;
        struct trace_pid_list *no_pid_list;
        struct trace_pid_list *pid_list;

        /* Nothing to do if we are already tracing */
        if (!this_cpu_read(tr->array_buffer.data->ignore_pid))
                return;

        pid_list = rcu_dereference_sched(tr->filtered_pids);
        no_pid_list = rcu_dereference_sched(tr->filtered_no_pids);

        this_cpu_write(tr->array_buffer.data->ignore_pid,
                       trace_ignore_this_task(pid_list, no_pid_list, task));
}

static void
event_filter_pid_sched_wakeup_probe_post(void *data, struct task_struct *task)
{
        struct trace_array *tr = data;
        struct trace_pid_list *no_pid_list;
        struct trace_pid_list *pid_list;

        /* Nothing to do if we are not tracing */
        if (this_cpu_read(tr->array_buffer.data->ignore_pid))
                return;

        pid_list = rcu_dereference_sched(tr->filtered_pids);
        no_pid_list = rcu_dereference_sched(tr->filtered_no_pids);

        /* Set tracing if current is enabled */
        this_cpu_write(tr->array_buffer.data->ignore_pid,
                       trace_ignore_this_task(pid_list, no_pid_list, current));
}

static void unregister_pid_events(struct trace_array *tr)
{
        unregister_trace_sched_switch(event_filter_pid_sched_switch_probe_pre, tr);
        unregister_trace_sched_switch(event_filter_pid_sched_switch_probe_post, tr);

        unregister_trace_sched_wakeup(event_filter_pid_sched_wakeup_probe_pre, tr);
        unregister_trace_sched_wakeup(event_filter_pid_sched_wakeup_probe_post, tr);

        unregister_trace_sched_wakeup_new(event_filter_pid_sched_wakeup_probe_pre, tr);
        unregister_trace_sched_wakeup_new(event_filter_pid_sched_wakeup_probe_post, tr);

        unregister_trace_sched_waking(event_filter_pid_sched_wakeup_probe_pre, tr);
        unregister_trace_sched_waking(event_filter_pid_sched_wakeup_probe_post, tr);
}

static void __ftrace_clear_event_pids(struct trace_array *tr, int type)
{
        struct trace_pid_list *pid_list;
        struct trace_pid_list *no_pid_list;
        struct trace_event_file *file;
        int cpu;

        pid_list = rcu_dereference_protected(tr->filtered_pids,
                                             lockdep_is_held(&event_mutex));
        no_pid_list = rcu_dereference_protected(tr->filtered_no_pids,
                                             lockdep_is_held(&event_mutex));

        /* Make sure there's something to do */
        if (!pid_type_enabled(type, pid_list, no_pid_list))
                return;

        if (!still_need_pid_events(type, pid_list, no_pid_list)) {
                unregister_pid_events(tr);

                list_for_each_entry(file, &tr->events, list) {
                        clear_bit(EVENT_FILE_FL_PID_FILTER_BIT, &file->flags);
                }

                for_each_possible_cpu(cpu)
                        per_cpu_ptr(tr->array_buffer.data, cpu)->ignore_pid = false;
        }

        if (type & TRACE_PIDS)
                rcu_assign_pointer(tr->filtered_pids, NULL);

        if (type & TRACE_NO_PIDS)
                rcu_assign_pointer(tr->filtered_no_pids, NULL);

        /* Wait till all users are no longer using pid filtering */
        tracepoint_synchronize_unregister();

        if ((type & TRACE_PIDS) && pid_list)
                trace_pid_list_free(pid_list);

        if ((type & TRACE_NO_PIDS) && no_pid_list)
                trace_pid_list_free(no_pid_list);
}

static void ftrace_clear_event_pids(struct trace_array *tr, int type)
{
        mutex_lock(&event_mutex);
        __ftrace_clear_event_pids(tr, type);
        mutex_unlock(&event_mutex);
}

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

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

        list_del(&system->list);

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

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

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

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

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

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

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

        if (!--dir->nr_events) {
                eventfs_remove_dir(dir->ei);
                list_del(&dir->list);
                __put_system_dir(dir);
        }
}

void event_file_get(struct trace_event_file *file)
{
        refcount_inc(&file->ref);
}

void event_file_put(struct trace_event_file *file)
{
        if (WARN_ON_ONCE(!refcount_read(&file->ref))) {
                if (file->flags & EVENT_FILE_FL_FREED)
                        kmem_cache_free(file_cachep, file);
                return;
        }

        if (refcount_dec_and_test(&file->ref)) {
                /* Count should only go to zero when it is freed */
                if (WARN_ON_ONCE(!(file->flags & EVENT_FILE_FL_FREED)))
                        return;
                kmem_cache_free(file_cachep, file);
        }
}

static void remove_event_file_dir(struct trace_event_file *file)
{
        eventfs_remove_dir(file->ei);
        list_del(&file->list);
        remove_subsystem(file->system);
        free_event_filter(file->filter);
        file->flags |= EVENT_FILE_FL_FREED;
        event_file_put(file);

        /* Wake up hist poll waiters to notice the EVENT_FILE_FL_FREED flag. */
        hist_poll_wakeup();
}

/*
 * __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
 */
static int
__ftrace_set_clr_event_nolock(struct trace_array *tr, const char *match,
                              const char *sub, const char *event, int set,
                              const char *mod)
{
        struct trace_event_file *file;
        struct trace_event_call *call;
        char *module __free(kfree) = NULL;
        const char *name;
        int ret = -EINVAL;
        int eret = 0;

        if (mod) {
                char *p;

                module = kstrdup(mod, GFP_KERNEL);
                if (!module)
                        return -ENOMEM;

                /* Replace all '-' with '_' as that's what modules do */
                for (p = strchr(module, '-'); p; p = strchr(p + 1, '-'))
                        *p = '_';
        }

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

                call = file->event_call;

                /* If a module is specified, skip events that are not that module */
                if (module && (!call->module || strcmp(module_name(call->module), module)))
                        continue;

                name = trace_event_name(call);

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

                if (call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
                        continue;

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

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

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

                ret = ftrace_event_enable_disable(file, set);

                /*
                 * Save the first error and return that. Some events
                 * may still have been enabled, but let the user
                 * know that something went wrong.
                 */
                if (ret && !eret)
                        eret = ret;

                ret = eret;
        }

        /*
         * If this is a module setting and nothing was found,
         * check if the module was loaded. If it wasn't cache it.
         */
        if (module && ret == -EINVAL && !eret)
                ret = cache_mod(tr, module, set, match, sub, event);

        return ret;
}

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

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

        return ret;
}

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

        if (!tr)
                return -ENOENT;

        /* Modules events can be appended with :mod:<module> */
        mod = strstr(buf, ":mod:");
        if (mod) {
                *mod = '\0';
                /* move to the module name */
                mod += 5;
        }

        /*
         * 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;
        } else if (mod) {
                /* Allow wildcard for no length or star */
                if (!strlen(match) || strcmp(match, "*") == 0)
                        match = NULL;
        }

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

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

        return ret;
}

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

        if (!tr)
                return -ENODEV;

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

/**
 * trace_array_set_clr_event - enable or disable an event for a trace array.
 * @tr: concerned trace array.
 * @system: system name to match (NULL for any system)
 * @event: event name to match (NULL for all events, within system)
 * @enable: true to enable, false 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_array_set_clr_event(struct trace_array *tr, const char *system,
                const char *event, bool enable)
{
        int set;

        if (!tr)
                return -ENOENT;

        set = (enable == true) ? 1 : 0;
        return __ftrace_set_clr_event(tr, NULL, system, event, set, NULL);
}
EXPORT_SYMBOL_GPL(trace_array_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(tr);
        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;

                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 trace_event_file *file = v;
        struct trace_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 &&
                    !(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE))
                        return file;
        }

        return NULL;
}

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

        mutex_lock(&event_mutex);

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

enum set_event_iter_type {
        SET_EVENT_FILE,
        SET_EVENT_MOD,
};

struct set_event_iter {
        enum set_event_iter_type        type;
        union {
                struct trace_event_file *file;
                struct event_mod_load   *event_mod;
        };
};

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

        (*pos)++;

        if (iter->type == SET_EVENT_FILE) {
                file = iter->file;
                list_for_each_entry_continue(file, &tr->events, list) {
                        if (file->flags & EVENT_FILE_FL_ENABLED) {
                                iter->file = file;
                                return iter;
                        }
                }
#ifdef CONFIG_MODULES
                iter->type = SET_EVENT_MOD;
                iter->event_mod = list_entry(&tr->mod_events, struct event_mod_load, list);
#endif
        }

#ifdef CONFIG_MODULES
        list_for_each_entry_continue(iter->event_mod, &tr->mod_events, list)
                return iter;
#endif

        /*
         * The iter is allocated in s_start() and passed via the 'v'
         * parameter. To stop the iterator, NULL must be returned. But
         * the return value is what the 'v' parameter in s_stop() receives
         * and frees. Free iter here as it will no longer be used.
         */
        kfree(iter);
        return NULL;
}

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

        iter = kzalloc_obj(*iter);
        mutex_lock(&event_mutex);
        if (!iter)
                return NULL;

        iter->type = SET_EVENT_FILE;
        iter->file = list_entry(&tr->events, struct trace_event_file, list);

        for (l = 0; l <= *pos; ) {
                iter = s_next(m, iter, &l);
                if (!iter)
                        break;
        }
        return iter;
}

static int t_show(struct seq_file *m, void *v)
{
        struct trace_event_file *file = v;
        struct trace_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", trace_event_name(call));

        return 0;
}

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

static int get_call_len(struct trace_event_call *call)
{
        int len;

        /* Get the length of "<system>:<event>" */
        len = strlen(call->class->system) + 1;
        len += strlen(trace_event_name(call));

        /* Set the index to 32 bytes to separate event from data */
        return len >= 32 ? 1 : 32 - len;
}

/**
 * t_show_filters - seq_file callback to display active event filters
 * @m: The seq_file interface for formatted output
 * @v: The current trace_event_file being iterated
 *
 * Identifies and prints active filters for the current event file in the
 * iteration. If a filter is applied to the current event and, if so,
 * prints the system name, event name, and the filter string.
 */
static int t_show_filters(struct seq_file *m, void *v)
{
        struct trace_event_file *file = v;
        struct trace_event_call *call = file->event_call;
        struct event_filter *filter;
        int len;

        guard(rcu)();
        filter = rcu_dereference(file->filter);
        if (!filter || !filter->filter_string)
                return 0;

        len = get_call_len(call);

        seq_printf(m, "%s:%s%*.s%s\n", call->class->system,
                   trace_event_name(call), len, "", filter->filter_string);

        return 0;
}

/**
 * t_show_triggers - seq_file callback to display active event triggers
 * @m: The seq_file interface for formatted output
 * @v: The current trace_event_file being iterated
 *
 * Iterates through the trigger list of the current event file and prints
 * each active trigger's configuration using its associated print
 * operation.
 */
static int t_show_triggers(struct seq_file *m, void *v)
{
        struct trace_event_file *file = v;
        struct trace_event_call *call = file->event_call;
        struct event_trigger_data *data;
        int len;

        /*
         * The event_mutex is held by t_start(), protecting the
         * file->triggers list traversal.
         */
        if (list_empty(&file->triggers))
                return 0;

        len = get_call_len(call);

        list_for_each_entry_rcu(data, &file->triggers, list) {
                seq_printf(m, "%s:%s%*.s", call->class->system,
                           trace_event_name(call), len, "");

                data->cmd_ops->print(m, data);
        }

        return 0;
}

#ifdef CONFIG_MODULES
static int s_show(struct seq_file *m, void *v)
{
        struct set_event_iter *iter = v;
        const char *system;
        const char *event;

        if (iter->type == SET_EVENT_FILE)
                return t_show(m, iter->file);

        /* When match is set, system and event are not */
        if (iter->event_mod->match) {
                seq_printf(m, "%s:mod:%s\n", iter->event_mod->match,
                           iter->event_mod->module);
                return 0;
        }

        system = iter->event_mod->system ? : "*";
        event = iter->event_mod->event ? : "*";

        seq_printf(m, "%s:%s:mod:%s\n", system, event, iter->event_mod->module);

        return 0;
}
#else /* CONFIG_MODULES */
static int s_show(struct seq_file *m, void *v)
{
        struct set_event_iter *iter = v;

        return t_show(m, iter->file);
}
#endif

static void s_stop(struct seq_file *m, void *v)
{
        kfree(v);
        t_stop(m, NULL);
}

static void *
__next(struct seq_file *m, void *v, loff_t *pos, int type)
{
        struct trace_array *tr = m->private;
        struct trace_pid_list *pid_list;

        if (type == TRACE_PIDS)
                pid_list = rcu_dereference_sched(tr->filtered_pids);
        else
                pid_list = rcu_dereference_sched(tr->filtered_no_pids);

        return trace_pid_next(pid_list, v, pos);
}

static void *
p_next(struct seq_file *m, void *v, loff_t *pos)
{
        return __next(m, v, pos, TRACE_PIDS);
}

static void *
np_next(struct seq_file *m, void *v, loff_t *pos)
{
        return __next(m, v, pos, TRACE_NO_PIDS);
}

static void *__start(struct seq_file *m, loff_t *pos, int type)
        __acquires(RCU)
{
        struct trace_pid_list *pid_list;
        struct trace_array *tr = m->private;

        /*
         * Grab the mutex, to keep calls to p_next() having the same
         * tr->filtered_pids as p_start() has.
         * If we just passed the tr->filtered_pids around, then RCU would
         * have been enough, but doing that makes things more complex.
         */
        mutex_lock(&event_mutex);
        rcu_read_lock_sched();

        if (type == TRACE_PIDS)
                pid_list = rcu_dereference_sched(tr->filtered_pids);
        else
                pid_list = rcu_dereference_sched(tr->filtered_no_pids);

        if (!pid_list)
                return NULL;

        return trace_pid_start(pid_list, pos);
}

static void *p_start(struct seq_file *m, loff_t *pos)
        __acquires(RCU)
{
        return __start(m, pos, TRACE_PIDS);
}

static void *np_start(struct seq_file *m, loff_t *pos)
        __acquires(RCU)
{
        return __start(m, pos, TRACE_NO_PIDS);
}

static void p_stop(struct seq_file *m, void *p)
        __releases(RCU)
{
        rcu_read_unlock_sched();
        mutex_unlock(&event_mutex);
}

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

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

        if (!file)
                return -ENODEV;

        if (flags & EVENT_FILE_FL_ENABLED &&
            !(flags & EVENT_FILE_FL_SOFT_DISABLED))
                strcpy(buf, "1");

        if (atomic_read(&file->sm_ref) != 0)
                strcat(buf, "*");

        strcat(buf, "\n");

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

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

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

        guard(mutex)(&event_mutex);

        switch (val) {
        case 0:
        case 1:
                file = event_file_file(filp);
                if (!file)
                        return -ENODEV;
                ret = tracing_update_buffers(file->tr);
                if (ret < 0)
                        return ret;
                ret = ftrace_event_enable_disable(file, val);
                if (ret < 0)
                        return ret;
                break;

        default:
                return -EINVAL;
        }

        *ppos += cnt;

        return cnt;
}

/*
 * Returns:
 *   0 : no events exist?
 *   1 : all events are disabled
 *   2 : all events are enabled
 *   3 : some events are enabled and some are enabled
 */
int trace_events_enabled(struct trace_array *tr, const char *system)
{
        struct trace_event_call *call;
        struct trace_event_file *file;
        int set = 0;

        guard(mutex)(&event_mutex);

        list_for_each_entry(file, &tr->events, list) {
                call = file->event_call;
                if ((call->flags & TRACE_EVENT_FL_IGNORE_ENABLE) ||
                    !trace_event_name(call) || !call->class || !call->class->reg)
                        continue;

                if (system && strcmp(call->class->system, system) != 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 & EVENT_FILE_FL_ENABLED));

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

        return set;
}

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 trace_subsystem_dir *dir = filp->private_data;
        struct event_subsystem *system = dir->subsystem;
        struct trace_array *tr = dir->tr;
        char buf[2];
        int set;
        int ret;

        set = trace_events_enabled(tr, system ? system->name : NULL);

        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 trace_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(dir->tr);
        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, NULL);
        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 trace_event_file *file = event_file_data(m->private);
        struct trace_event_call *call = file->event_call;
        struct list_head *common_head = &ftrace_common_fields;
        struct list_head *head = trace_get_fields(call);
        struct list_head *node = v;

        (*pos)++;

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

        case FORMAT_FIELD_SEPERATOR:
                node = head;
                break;

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

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

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

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

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

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

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

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

        return 0;
}

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

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

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

        return p;
}

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

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

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

        /* Do we want to hide event format files on tracefs lockdown? */

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

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

        return 0;
}

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

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

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

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

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

        if (*ppos)
                return 0;

        s = kmalloc_obj(*s);

        if (!s)
                return -ENOMEM;

        trace_seq_init(s);

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

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

        kfree(s);

        return r;
}

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

        if (cnt >= PAGE_SIZE)
                return -EINVAL;

        buf = memdup_user_nul(ubuf, cnt);
        if (IS_ERR(buf))
                return PTR_ERR(buf);

        mutex_lock(&event_mutex);
        file = event_file_file(filp);
        if (file) {
                if (file->flags & EVENT_FILE_FL_FREED)
                        err = -ENODEV;
                else
                        err = apply_event_filter(file, buf);
        }
        mutex_unlock(&event_mutex);

        kfree(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 trace_subsystem_dir *dir = NULL, *iter_dir;
        struct trace_array *tr = NULL, *iter_tr;
        struct event_subsystem *system = NULL;
        int ret;

        if (unlikely(tracing_disabled))
                return -ENODEV;

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

        if (!system)
                return -ENODEV;

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

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

        return ret;
}

static int system_tr_open(struct inode *inode, struct file *filp)
{
        struct trace_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_obj(*dir);
        if (!dir)
                return -ENOMEM;

        ret = tracing_open_generic_tr(inode, filp);
        if (ret < 0) {
                kfree(dir);
                return ret;
        }
        dir->tr = tr;
        filp->private_data = dir;

        return 0;
}

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

        trace_array_put(dir->tr);

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

        return 0;
}

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

        if (*ppos)
                return 0;

        s = kmalloc_obj(*s);
        if (!s)
                return -ENOMEM;

        trace_seq_init(s);

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

        kfree(s);

        return r;
}

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

        if (cnt >= PAGE_SIZE)
                return -EINVAL;

        buf = memdup_user_nul(ubuf, cnt);
        if (IS_ERR(buf))
                return PTR_ERR(buf);

        err = apply_subsystem_event_filter(dir, buf);
        kfree(buf);
        if (err < 0)
                return err;

        *ppos += cnt;

        return cnt;
}

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

        if (*ppos)
                return 0;

        s = kmalloc_obj(*s);
        if (!s)
                return -ENOMEM;

        trace_seq_init(s);

        ring_buffer_print_page_header(tr->array_buffer.buffer, s);
        r = simple_read_from_buffer(ubuf, cnt, ppos,
                                    s->buffer, trace_seq_used(s));

        kfree(s);

        return r;
}

static ssize_t
show_header_event_file(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
{
        struct trace_seq *s;
        int r;

        if (*ppos)
                return 0;

        s = kmalloc_obj(*s);
        if (!s)
                return -ENOMEM;

        trace_seq_init(s);

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

        kfree(s);

        return r;
}

static void ignore_task_cpu(void *data)
{
        struct trace_array *tr = data;
        struct trace_pid_list *pid_list;
        struct trace_pid_list *no_pid_list;

        /*
         * This function is called by on_each_cpu() while the
         * event_mutex is held.
         */
        pid_list = rcu_dereference_protected(tr->filtered_pids,
                                             mutex_is_locked(&event_mutex));
        no_pid_list = rcu_dereference_protected(tr->filtered_no_pids,
                                             mutex_is_locked(&event_mutex));

        this_cpu_write(tr->array_buffer.data->ignore_pid,
                       trace_ignore_this_task(pid_list, no_pid_list, current));
}

static void register_pid_events(struct trace_array *tr)
{
        /*
         * Register a probe that is called before all other probes
         * to set ignore_pid if next or prev do not match.
         * Register a probe this is called after all other probes
         * to only keep ignore_pid set if next pid matches.
         */
        register_trace_prio_sched_switch(event_filter_pid_sched_switch_probe_pre,
                                         tr, INT_MAX);
        register_trace_prio_sched_switch(event_filter_pid_sched_switch_probe_post,
                                         tr, 0);

        register_trace_prio_sched_wakeup(event_filter_pid_sched_wakeup_probe_pre,
                                         tr, INT_MAX);
        register_trace_prio_sched_wakeup(event_filter_pid_sched_wakeup_probe_post,
                                         tr, 0);

        register_trace_prio_sched_wakeup_new(event_filter_pid_sched_wakeup_probe_pre,
                                             tr, INT_MAX);
        register_trace_prio_sched_wakeup_new(event_filter_pid_sched_wakeup_probe_post,
                                             tr, 0);

        register_trace_prio_sched_waking(event_filter_pid_sched_wakeup_probe_pre,
                                         tr, INT_MAX);
        register_trace_prio_sched_waking(event_filter_pid_sched_wakeup_probe_post,
                                         tr, 0);
}

static ssize_t
event_pid_write(struct file *filp, const char __user *ubuf,
                size_t cnt, loff_t *ppos, int type)
{
        struct seq_file *m = filp->private_data;
        struct trace_array *tr = m->private;
        struct trace_pid_list *filtered_pids = NULL;
        struct trace_pid_list *other_pids = NULL;
        struct trace_pid_list *pid_list;
        struct trace_event_file *file;
        ssize_t ret;

        if (!cnt)
                return 0;

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

        guard(mutex)(&event_mutex);

        if (type == TRACE_PIDS) {
                filtered_pids = rcu_dereference_protected(tr->filtered_pids,
                                                          lockdep_is_held(&event_mutex));
                other_pids = rcu_dereference_protected(tr->filtered_no_pids,
                                                          lockdep_is_held(&event_mutex));
        } else {
                filtered_pids = rcu_dereference_protected(tr->filtered_no_pids,
                                                          lockdep_is_held(&event_mutex));
                other_pids = rcu_dereference_protected(tr->filtered_pids,
                                                          lockdep_is_held(&event_mutex));
        }

        ret = trace_pid_write(filtered_pids, &pid_list, ubuf, cnt);
        if (ret < 0)
                return ret;

        if (type == TRACE_PIDS)
                rcu_assign_pointer(tr->filtered_pids, pid_list);
        else
                rcu_assign_pointer(tr->filtered_no_pids, pid_list);

        list_for_each_entry(file, &tr->events, list) {
                set_bit(EVENT_FILE_FL_PID_FILTER_BIT, &file->flags);
        }

        if (filtered_pids) {
                tracepoint_synchronize_unregister();
                trace_pid_list_free(filtered_pids);
        } else if (pid_list && !other_pids) {
                register_pid_events(tr);
        }

        /*
         * Ignoring of pids is done at task switch. But we have to
         * check for those tasks that are currently running.
         * Always do this in case a pid was appended or removed.
         */
        on_each_cpu(ignore_task_cpu, tr, 1);

        *ppos += ret;

        return ret;
}

static ssize_t
ftrace_event_pid_write(struct file *filp, const char __user *ubuf,
                       size_t cnt, loff_t *ppos)
{
        return event_pid_write(filp, ubuf, cnt, ppos, TRACE_PIDS);
}

static ssize_t
ftrace_event_npid_write(struct file *filp, const char __user *ubuf,
                        size_t cnt, loff_t *ppos)
{
        return event_pid_write(filp, ubuf, cnt, ppos, TRACE_NO_PIDS);
}

static int ftrace_event_avail_open(struct inode *inode, struct file *file);
static int ftrace_event_set_open(struct inode *inode, struct file *file);
static int ftrace_event_show_filters_open(struct inode *inode, struct file *file);
static int ftrace_event_show_triggers_open(struct inode *inode, struct file *file);
static int ftrace_event_set_pid_open(struct inode *inode, struct file *file);
static int ftrace_event_set_npid_open(struct inode *inode, struct file *file);
static int ftrace_event_release(struct inode *inode, struct file *file);

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

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

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

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

static const struct seq_operations show_set_pid_seq_ops = {
        .start = p_start,
        .next = p_next,
        .show = trace_pid_show,
        .stop = p_stop,
};

static const struct seq_operations show_set_no_pid_seq_ops = {
        .start = np_start,
        .next = np_next,
        .show = trace_pid_show,
        .stop = p_stop,
};

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

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

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

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

static const struct file_operations ftrace_set_event_pid_fops = {
        .open = ftrace_event_set_pid_open,
        .read = seq_read,
        .write = ftrace_event_pid_write,
        .llseek = seq_lseek,
        .release = ftrace_event_release,
};

static const struct file_operations ftrace_set_event_notrace_pid_fops = {
        .open = ftrace_event_set_npid_open,
        .read = seq_read,
        .write = ftrace_event_npid_write,
        .llseek = seq_lseek,
        .release = ftrace_event_release,
};

static const struct file_operations ftrace_enable_fops = {
        .open = tracing_open_file_tr,
        .read = event_enable_read,
        .write = event_enable_write,
        .release = tracing_release_file_tr,
        .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,
};

#ifdef CONFIG_PERF_EVENTS
static const struct file_operations ftrace_event_id_fops = {
        .read = event_id_read,
        .llseek = default_llseek,
};
#endif

static const struct file_operations ftrace_event_filter_fops = {
        .open = tracing_open_file_tr,
        .read = event_filter_read,
        .write = event_filter_write,
        .release = tracing_release_file_tr,
        .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_page_fops = {
        .open = tracing_open_generic_tr,
        .read = show_header_page_file,
        .llseek = default_llseek,
        .release = tracing_release_generic_tr,
};

static const struct file_operations ftrace_show_header_event_fops = {
        .open = tracing_open_generic_tr,
        .read = show_header_event_file,
        .llseek = default_llseek,
        .release = tracing_release_generic_tr,
};

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

        ret = security_locked_down(LOCKDOWN_TRACEFS);
        if (ret)
                return ret;

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

        return ret;
}

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

        trace_array_put(tr);

        return seq_release(inode, file);
}

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

        /* Checks for tracefs lockdown */
        return ftrace_event_open(inode, file, seq_ops);
}

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

        ret = tracing_check_open_get_tr(tr);
        if (ret)
                return ret;

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

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

/**
 * ftrace_event_show_filters_open - open interface for set_event_filters
 * @inode: The inode of the file
 * @file: The file being opened
 *
 * Connects the set_event_filters file to the sequence operations
 * required to iterate over and display active event filters.
 */
static int
ftrace_event_show_filters_open(struct inode *inode, struct file *file)
{
        return ftrace_event_open(inode, file, &show_show_event_filters_seq_ops);
}

/**
 * ftrace_event_show_triggers_open - open interface for show_event_triggers
 * @inode: The inode of the file
 * @file: The file being opened
 *
 * Connects the show_event_triggers file to the sequence operations
 * required to iterate over and display active event triggers.
 */
static int
ftrace_event_show_triggers_open(struct inode *inode, struct file *file)
{
        return ftrace_event_open(inode, file, &show_show_event_triggers_seq_ops);
}

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

        ret = tracing_check_open_get_tr(tr);
        if (ret)
                return ret;

        if ((file->f_mode & FMODE_WRITE) &&
            (file->f_flags & O_TRUNC))
                ftrace_clear_event_pids(tr, TRACE_PIDS);

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

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

        ret = tracing_check_open_get_tr(tr);
        if (ret)
                return ret;

        if ((file->f_mode & FMODE_WRITE) &&
            (file->f_flags & O_TRUNC))
                ftrace_clear_event_pids(tr, TRACE_NO_PIDS);

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

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

        /* need to create new entry */
        system = kmalloc_obj(*system);
        if (!system)
                return NULL;

        system->ref_count = 1;

        /* Only allocate if dynamic (kprobes and modules) */
        system->name = kstrdup_const(name, GFP_KERNEL);
        if (!system->name)
                goto out_free;

        system->filter = kzalloc_obj(struct event_filter);
        if (!system->filter)
                goto out_free;

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

        return system;

 out_free:
        kfree_const(system->name);
        kfree(system);
        return NULL;
}

static int system_callback(const char *name, umode_t *mode, void **data,
                    const struct file_operations **fops)
{
        if (strcmp(name, "filter") == 0)
                *fops = &ftrace_subsystem_filter_fops;

        else if (strcmp(name, "enable") == 0)
                *fops = &ftrace_system_enable_fops;

        else
                return 0;

        *mode = TRACE_MODE_WRITE;
        return 1;
}

static struct eventfs_inode *
event_subsystem_dir(struct trace_array *tr, const char *name,
                    struct trace_event_file *file, struct eventfs_inode *parent)
{
        struct event_subsystem *system, *iter;
        struct trace_subsystem_dir *dir;
        struct eventfs_inode *ei;
        int nr_entries;
        static struct eventfs_entry system_entries[] = {
                {
                        .name           = "filter",
                        .callback       = system_callback,
                },
                {
                        .name           = "enable",
                        .callback       = system_callback,
                }
        };

        /* 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->ei;
                }
        }

        /* Now see if the system itself exists. */
        system = NULL;
        list_for_each_entry(iter, &event_subsystems, list) {
                if (strcmp(iter->name, name) == 0) {
                        system = iter;
                        break;
                }
        }

        dir = kmalloc_obj(*dir);
        if (!dir)
                goto out_fail;

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

        /* ftrace only has directories no files */
        if (strcmp(name, "ftrace") == 0)
                nr_entries = 0;
        else
                nr_entries = ARRAY_SIZE(system_entries);

        ei = eventfs_create_dir(name, parent, system_entries, nr_entries, dir);
        if (IS_ERR(ei)) {
                pr_warn("Failed to create system directory %s\n", name);
                __put_system(system);
                goto out_free;
        }

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

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

        return dir->ei;

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

static int
event_define_fields(struct trace_event_call *call)
{
        struct list_head *head;
        int ret = 0;

        /*
         * 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)) {
                struct trace_event_fields *field = call->class->fields_array;
                unsigned int offset = sizeof(struct trace_entry);

                for (; field->type; field++) {
                        if (field->type == TRACE_FUNCTION_TYPE) {
                                field->define_fields(call);
                                break;
                        }

                        offset = ALIGN(offset, field->align);
                        ret = trace_define_field_ext(call, field->type, field->name,
                                                 offset, field->size,
                                                 field->is_signed, field->filter_type,
                                                 field->len, field->needs_test);
                        if (WARN_ON_ONCE(ret)) {
                                pr_err("error code is %d\n", ret);
                                break;
                        }

                        offset += field->size;
                }
        }

        return ret;
}

static int event_callback(const char *name, umode_t *mode, void **data,
                          const struct file_operations **fops)
{
        struct trace_event_file *file = *data;
        struct trace_event_call *call = file->event_call;

        if (strcmp(name, "format") == 0) {
                *mode = TRACE_MODE_READ;
                *fops = &ftrace_event_format_fops;
                return 1;
        }

        /*
         * Only event directories that can be enabled should have
         * triggers or filters, with the exception of the "print"
         * event that can have a "trigger" file.
         */
        if (!(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)) {
                if (call->class->reg && strcmp(name, "enable") == 0) {
                        *mode = TRACE_MODE_WRITE;
                        *fops = &ftrace_enable_fops;
                        return 1;
                }

                if (strcmp(name, "filter") == 0) {
                        *mode = TRACE_MODE_WRITE;
                        *fops = &ftrace_event_filter_fops;
                        return 1;
                }
        }

        if (!(call->flags & TRACE_EVENT_FL_IGNORE_ENABLE) ||
            strcmp(trace_event_name(call), "print") == 0) {
                if (strcmp(name, "trigger") == 0) {
                        *mode = TRACE_MODE_WRITE;
                        *fops = &event_trigger_fops;
                        return 1;
                }
        }

#ifdef CONFIG_PERF_EVENTS
        if (call->event.type && call->class->reg &&
            strcmp(name, "id") == 0) {
                *mode = TRACE_MODE_READ;
                *data = (void *)(long)call->event.type;
                *fops = &ftrace_event_id_fops;
                return 1;
        }
#endif

#ifdef CONFIG_HIST_TRIGGERS
        if (strcmp(name, "hist") == 0) {
                *mode = TRACE_MODE_READ;
                *fops = &event_hist_fops;
                return 1;
        }
#endif
#ifdef CONFIG_HIST_TRIGGERS_DEBUG
        if (strcmp(name, "hist_debug") == 0) {
                *mode = TRACE_MODE_READ;
                *fops = &event_hist_debug_fops;
                return 1;
        }
#endif
#ifdef CONFIG_TRACE_EVENT_INJECT
        if (call->event.type && call->class->reg &&
            strcmp(name, "inject") == 0) {
                *mode = 0200;
                *fops = &event_inject_fops;
                return 1;
        }
#endif
        return 0;
}

/* The file is incremented on creation and freeing the enable file decrements it */
static void event_release(const char *name, void *data)
{
        struct trace_event_file *file = data;

        event_file_put(file);
}

static int
event_create_dir(struct eventfs_inode *parent, struct trace_event_file *file)
{
        struct trace_event_call *call = file->event_call;
        struct trace_array *tr = file->tr;
        struct eventfs_inode *e_events;
        struct eventfs_inode *ei;
        const char *name;
        int nr_entries;
        int ret;
        static struct eventfs_entry event_entries[] = {
                {
                        .name           = "enable",
                        .callback       = event_callback,
                        .release        = event_release,
                },
                {
                        .name           = "filter",
                        .callback       = event_callback,
                },
                {
                        .name           = "trigger",
                        .callback       = event_callback,
                },
                {
                        .name           = "format",
                        .callback       = event_callback,
                },
#ifdef CONFIG_PERF_EVENTS
                {
                        .name           = "id",
                        .callback       = event_callback,
                },
#endif
#ifdef CONFIG_HIST_TRIGGERS
                {
                        .name           = "hist",
                        .callback       = event_callback,
                },
#endif
#ifdef CONFIG_HIST_TRIGGERS_DEBUG
                {
                        .name           = "hist_debug",
                        .callback       = event_callback,
                },
#endif
#ifdef CONFIG_TRACE_EVENT_INJECT
                {
                        .name           = "inject",
                        .callback       = event_callback,
                },
#endif
        };

        /*
         * If the trace point header did not define TRACE_SYSTEM
         * then the system would be called "TRACE_SYSTEM". This should
         * never happen.
         */
        if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0))
                return -ENODEV;

        e_events = event_subsystem_dir(tr, call->class->system, file, parent);
        if (!e_events)
                return -ENOMEM;

        nr_entries = ARRAY_SIZE(event_entries);

        name = trace_event_name(call);
        ei = eventfs_create_dir(name, e_events, event_entries, nr_entries, file);
        if (IS_ERR(ei)) {
                pr_warn("Could not create tracefs '%s' directory\n", name);
                return -1;
        }

        file->ei = ei;

        ret = event_define_fields(call);
        if (ret < 0) {
                pr_warn("Could not initialize trace point events/%s\n", name);
                return ret;
        }

        /* Gets decremented on freeing of the "enable" file */
        event_file_get(file);

        return 0;
}

static void remove_event_from_tracers(struct trace_event_call *call)
{
        struct trace_event_file *file;
        struct trace_array *tr;

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

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

static void event_remove(struct trace_event_call *call)
{
        struct trace_array *tr;
        struct trace_event_file *file;

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

                if (file->flags & EVENT_FILE_FL_WAS_ENABLED)
                        tr->clear_trace = true;

                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_trace_event(&call->event);
        remove_event_from_tracers(call);
        list_del(&call->list);
}

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

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

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

        return ret;
}

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

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

        down_write(&trace_event_sem);
        list_add(&call->list, &ftrace_events);
        up_write(&trace_event_sem);

        if (call->flags & TRACE_EVENT_FL_DYNAMIC)
                atomic_set(&call->refcnt, 0);
        else
                call->module = mod;

        return 0;
}

static char *eval_replace(char *ptr, struct trace_eval_map *map, int len)
{
        int rlen;
        int elen;

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

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

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

        return ptr + elen;
}

static void update_event_printk(struct trace_event_call *call,
                                struct trace_eval_map *map)
{
        char *ptr;
        int quote = 0;
        int len = strlen(map->eval_string);

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

static void add_str_to_module(struct module *module, char *str)
{
        struct module_string *modstr;

        modstr = kmalloc_obj(*modstr);

        /*
         * If we failed to allocate memory here, then we'll just
         * let the str memory leak when the module is removed.
         * If this fails to allocate, there's worse problems than
         * a leaked string on module removal.
         */
        if (WARN_ON_ONCE(!modstr))
                return;

        modstr->module = module;
        modstr->str = str;

        list_add(&modstr->next, &module_strings);
}

#define ATTRIBUTE_STR "__attribute__("
#define ATTRIBUTE_STR_LEN (sizeof(ATTRIBUTE_STR) - 1)

/* Remove all __attribute__() from @type. Return allocated string or @type. */
static char *sanitize_field_type(const char *type)
{
        char *attr, *tmp, *next, *ret = (char *)type;
        int depth;

        next = (char *)type;
        while ((attr = strstr(next, ATTRIBUTE_STR))) {
                /* Retry if "__attribute__(" is a part of another word. */
                if (attr != next && !isspace(attr[-1])) {
                        next = attr + ATTRIBUTE_STR_LEN;
                        continue;
                }

                if (ret == type) {
                        ret = kstrdup(type, GFP_KERNEL);
                        if (WARN_ON_ONCE(!ret))
                                return NULL;
                        attr = ret + (attr - type);
                }

                /* the ATTRIBUTE_STR already has the first '(' */
                depth = 1;
                next = attr + ATTRIBUTE_STR_LEN;
                do {
                        tmp = strpbrk(next, "()");
                        /* There is unbalanced parentheses */
                        if (WARN_ON_ONCE(!tmp)) {
                                kfree(ret);
                                return (char *)type;
                        }

                        if (*tmp == '(')
                                depth++;
                        else
                                depth--;
                        next = tmp + 1;
                } while (depth > 0);
                next = skip_spaces(next);
                strcpy(attr, next);
                next = attr;
        }
        return ret;
}

static char *find_replacable_eval(const char *type, const char *eval_string,
                                  int len)
{
        char *ptr;

        if (!eval_string)
                return NULL;

        ptr = strchr(type, '[');
        if (!ptr)
                return NULL;
        ptr++;

        if (!isalpha(*ptr) && *ptr != '_')
                return NULL;

        if (strncmp(eval_string, ptr, len) != 0)
                return NULL;

        return ptr;
}

static void update_event_fields(struct trace_event_call *call,
                                struct trace_eval_map *map)
{
        struct ftrace_event_field *field;
        const char *eval_string = NULL;
        struct list_head *head;
        int len = 0;
        char *ptr;
        char *str;

        /* Dynamic events should never have field maps */
        if (call->flags & TRACE_EVENT_FL_DYNAMIC)
                return;

        if (map) {
                eval_string = map->eval_string;
                len = strlen(map->eval_string);
        }

        head = trace_get_fields(call);
        list_for_each_entry(field, head, link) {
                str = sanitize_field_type(field->type);
                if (!str)
                        return;

                ptr = find_replacable_eval(str, eval_string, len);
                if (ptr) {
                        if (str == field->type) {
                                str = kstrdup(field->type, GFP_KERNEL);
                                if (WARN_ON_ONCE(!str))
                                        return;
                                ptr = str + (ptr - field->type);
                        }

                        ptr = eval_replace(ptr, map, len);
                        /* enum/sizeof string smaller than value */
                        if (WARN_ON_ONCE(!ptr)) {
                                kfree(str);
                                continue;
                        }
                }

                if (str == field->type)
                        continue;
                /*
                 * If the event is part of a module, then we need to free the string
                 * when the module is removed. Otherwise, it will stay allocated
                 * until a reboot.
                 */
                if (call->module)
                        add_str_to_module(call->module, str);

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

/* Update all events for replacing eval and sanitizing */
void trace_event_update_all(struct trace_eval_map **map, int len)
{
        struct trace_event_call *call, *p;
        const char *last_system = NULL;
        bool first = false;
        bool updated;
        int last_i;
        int i;

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

                updated = false;
                /*
                 * Since calls are grouped by systems, the likelihood that the
                 * next call in the iteration belongs to the same system as the
                 * previous call is high. As an optimization, we skip searching
                 * for a map[] that matches the call's system if the last call
                 * was from the same system. That's what last_i is for. If the
                 * call has the same system as the previous call, then last_i
                 * will be the index of the first map[] that has a matching
                 * system.
                 */
                for (i = last_i; i < len; i++) {
                        if (call->class->system == map[i]->system) {
                                /* Save the first system if need be */
                                if (first) {
                                        last_i = i;
                                        first = false;
                                }
                                update_event_printk(call, map[i]);
                                update_event_fields(call, map[i]);
                                updated = true;
                        }
                }
                /* If not updated yet, update field for sanitizing. */
                if (!updated)
                        update_event_fields(call, NULL);
                cond_resched();
        }
        up_write(&trace_event_sem);
}

static bool event_in_systems(struct trace_event_call *call,
                             const char *systems)
{
        const char *system;
        const char *p;

        if (!systems)
                return true;

        system = call->class->system;
        p = strstr(systems, system);
        if (!p)
                return false;

        if (p != systems && !isspace(*(p - 1)) && *(p - 1) != ',')
                return false;

        p += strlen(system);
        return !*p || isspace(*p) || *p == ',';
}

#ifdef CONFIG_HIST_TRIGGERS
/*
 * Wake up waiter on the hist_poll_wq from irq_work because the hist trigger
 * may happen in any context.
 */
static void hist_poll_event_irq_work(struct irq_work *work)
{
        wake_up_all(&hist_poll_wq);
}

DEFINE_IRQ_WORK(hist_poll_work, hist_poll_event_irq_work);
DECLARE_WAIT_QUEUE_HEAD(hist_poll_wq);
#endif

static struct trace_event_file *
trace_create_new_event(struct trace_event_call *call,
                       struct trace_array *tr)
{
        struct trace_pid_list *no_pid_list;
        struct trace_pid_list *pid_list;
        struct trace_event_file *file;
        unsigned int first;

        if (!event_in_systems(call, tr->system_names))
                return NULL;

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

        pid_list = rcu_dereference_protected(tr->filtered_pids,
                                             lockdep_is_held(&event_mutex));
        no_pid_list = rcu_dereference_protected(tr->filtered_no_pids,
                                             lockdep_is_held(&event_mutex));

        if (!trace_pid_list_first(pid_list, &first) ||
            !trace_pid_list_first(no_pid_list, &first))
                file->flags |= EVENT_FILE_FL_PID_FILTER;

        file->event_call = call;
        file->tr = tr;
        atomic_set(&file->sm_ref, 0);
        atomic_set(&file->tm_ref, 0);
        INIT_LIST_HEAD(&file->triggers);
        list_add(&file->list, &tr->events);
        refcount_set(&file->ref, 1);

        return file;
}

#define MAX_BOOT_TRIGGERS 32

static struct boot_triggers {
        const char              *event;
        char                    *trigger;
} bootup_triggers[MAX_BOOT_TRIGGERS];

static char bootup_trigger_buf[COMMAND_LINE_SIZE];
static int nr_boot_triggers;

static __init int setup_trace_triggers(char *str)
{
        char *trigger;
        char *buf;
        int i;

        strscpy(bootup_trigger_buf, str, COMMAND_LINE_SIZE);
        trace_set_ring_buffer_expanded(NULL);
        disable_tracing_selftest("running event triggers");

        buf = bootup_trigger_buf;
        for (i = 0; i < MAX_BOOT_TRIGGERS; i++) {
                trigger = strsep(&buf, ",");
                if (!trigger)
                        break;
                bootup_triggers[i].event = strsep(&trigger, ".");
                bootup_triggers[i].trigger = trigger;
                if (!bootup_triggers[i].trigger)
                        break;
        }

        nr_boot_triggers = i;
        return 1;
}
__setup("trace_trigger=", setup_trace_triggers);

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

        file = trace_create_new_event(call, tr);
        /*
         * trace_create_new_event() returns ERR_PTR(-ENOMEM) if failed
         * allocation, or NULL if the event is not part of the tr->system_names.
         * When the event is not part of the tr->system_names, return zero, not
         * an error.
         */
        if (!file)
                return 0;

        if (IS_ERR(file))
                return PTR_ERR(file);

        if (eventdir_initialized)
                return event_create_dir(tr->event_dir, file);
        else
                return event_define_fields(call);
}

static void trace_early_triggers(struct trace_event_file *file, const char *name)
{
        int ret;
        int i;

        for (i = 0; i < nr_boot_triggers; i++) {
                if (strcmp(name, bootup_triggers[i].event))
                        continue;
                mutex_lock(&event_mutex);
                ret = trigger_process_regex(file, bootup_triggers[i].trigger);
                mutex_unlock(&event_mutex);
                if (ret)
                        pr_err("Failed to register trigger '%s' on event %s\n",
                               bootup_triggers[i].trigger,
                               bootup_triggers[i].event);
        }
}

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

        file = trace_create_new_event(call, tr);
        /*
         * trace_create_new_event() returns ERR_PTR(-ENOMEM) if failed
         * allocation, or NULL if the event is not part of the tr->system_names.
         * When the event is not part of the tr->system_names, return zero, not
         * an error.
         */
        if (!file)
                return 0;

        if (IS_ERR(file))
                return PTR_ERR(file);

        ret = event_define_fields(call);
        if (ret)
                return ret;

        trace_early_triggers(file, trace_event_name(call));

        return 0;
}

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

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

        guard(mutex)(&trace_types_lock);

        ret = __register_event(call, NULL);
        if (ret < 0)
                return ret;

        __add_event_to_tracers(call);
        return ret;
}
EXPORT_SYMBOL_GPL(trace_add_event_call);

/*
 * Must be called under locking of trace_types_lock, event_mutex and
 * trace_event_sem.
 */
static void __trace_remove_event_call(struct trace_event_call *call)
{
        event_remove(call);
        trace_destroy_fields(call);
}

static int probe_remove_event_call(struct trace_event_call *call)
{
        struct trace_array *tr;
        struct trace_event_file *file;

#ifdef CONFIG_PERF_EVENTS
        if (call->perf_refcount)
                return -EBUSY;
#endif
        do_for_each_event_file(tr, file) {
                if (file->event_call != call)
                        continue;
                /*
                 * We can't rely on ftrace_event_enable_disable(enable => 0)
                 * we are going to do, soft mode can suppress
                 * TRACE_REG_UNREGISTER.
                 */
                if (file->flags & EVENT_FILE_FL_ENABLED)
                        goto busy;

                if (file->flags & EVENT_FILE_FL_WAS_ENABLED)
                        tr->clear_trace = true;
                /*
                 * The do_for_each_event_file_safe() is
                 * a double loop. After finding the call for this
                 * trace_array, we use break to jump to the next
                 * trace_array.
                 */
                break;
        } while_for_each_event_file();

        __trace_remove_event_call(call);

        return 0;
 busy:
        /* No need to clear the trace now */
        list_for_each_entry(tr, &ftrace_trace_arrays, list) {
                tr->clear_trace = false;
        }
        return -EBUSY;
}

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

        lockdep_assert_held(&event_mutex);

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

        return ret;
}
EXPORT_SYMBOL_GPL(trace_remove_event_call);

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

#ifdef CONFIG_MODULES
static void update_mod_cache(struct trace_array *tr, struct module *mod)
{
        struct event_mod_load *event_mod, *n;

        list_for_each_entry_safe(event_mod, n, &tr->mod_events, list) {
                if (strcmp(event_mod->module, mod->name) != 0)
                        continue;

                __ftrace_set_clr_event_nolock(tr, event_mod->match,
                                              event_mod->system,
                                              event_mod->event, 1, mod->name);
                free_event_mod(event_mod);
        }
}

static void update_cache_events(struct module *mod)
{
        struct trace_array *tr;

        list_for_each_entry(tr, &ftrace_trace_arrays, list)
                update_mod_cache(tr, mod);
}

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

        if (!mod->num_trace_events)
                return;

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

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

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

        update_cache_events(mod);
}

static void trace_module_remove_events(struct module *mod)
{
        struct trace_event_call *call, *p;
        struct module_string *modstr, *m;

        down_write(&trace_event_sem);
        list_for_each_entry_safe(call, p, &ftrace_events, list) {
                if ((call->flags & TRACE_EVENT_FL_DYNAMIC) || !call->module)
                        continue;
                if (call->module == mod)
                        __trace_remove_event_call(call);
        }
        /* Check for any strings allocated for this module */
        list_for_each_entry_safe(modstr, m, &module_strings, next) {
                if (modstr->module != mod)
                        continue;
                list_del(&modstr->next);
                kfree(modstr->str);
                kfree(modstr);
        }
        up_write(&trace_event_sem);

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

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

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

        return NOTIFY_OK;
}

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

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

        lockdep_assert_held(&trace_event_sem);

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

/* Returns any file that matches the system and event */
struct trace_event_file *
__find_event_file(struct trace_array *tr, const char *system, const char *event)
{
        struct trace_event_file *file;
        struct trace_event_call *call;
        const char *name;

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

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

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

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

/* Returns valid trace event files that match system and event */
struct trace_event_file *
find_event_file(struct trace_array *tr, const char *system, const char *event)
{
        struct trace_event_file *file;

        file = __find_event_file(tr, system, event);
        if (!file || !file->event_call->class->reg ||
            file->event_call->flags & TRACE_EVENT_FL_IGNORE_ENABLE)
                return NULL;

        return file;
}

/**
 * trace_get_event_file - Find and return a trace event file
 * @instance: The name of the trace instance containing the event
 * @system: The name of the system containing the event
 * @event: The name of the event
 *
 * Return a trace event file given the trace instance name, trace
 * system, and trace event name.  If the instance name is NULL, it
 * refers to the top-level trace array.
 *
 * This function will look it up and return it if found, after calling
 * trace_array_get() to prevent the instance from going away, and
 * increment the event's module refcount to prevent it from being
 * removed.
 *
 * To release the file, call trace_put_event_file(), which will call
 * trace_array_put() and decrement the event's module refcount.
 *
 * Return: The trace event on success, ERR_PTR otherwise.
 */
struct trace_event_file *trace_get_event_file(const char *instance,
                                              const char *system,
                                              const char *event)
{
        struct trace_array *tr = top_trace_array();
        struct trace_event_file *file = NULL;
        int ret = -EINVAL;

        if (instance) {
                tr = trace_array_find_get(instance);
                if (!tr)
                        return ERR_PTR(-ENOENT);
        } else {
                ret = trace_array_get(tr);
                if (ret)
                        return ERR_PTR(ret);
        }

        guard(mutex)(&event_mutex);

        file = find_event_file(tr, system, event);
        if (!file) {
                trace_array_put(tr);
                return ERR_PTR(-EINVAL);
        }

        /* Don't let event modules unload while in use */
        ret = trace_event_try_get_ref(file->event_call);
        if (!ret) {
                trace_array_put(tr);
                return ERR_PTR(-EBUSY);
        }

        return file;
}
EXPORT_SYMBOL_GPL(trace_get_event_file);

/**
 * trace_put_event_file - Release a file from trace_get_event_file()
 * @file: The trace event file
 *
 * If a file was retrieved using trace_get_event_file(), this should
 * be called when it's no longer needed.  It will cancel the previous
 * trace_array_get() called by that function, and decrement the
 * event's module refcount.
 */
void trace_put_event_file(struct trace_event_file *file)
{
        mutex_lock(&event_mutex);
        trace_event_put_ref(file->event_call);
        mutex_unlock(&event_mutex);

        trace_array_put(file->tr);
}
EXPORT_SYMBOL_GPL(trace_put_event_file);

#ifdef CONFIG_DYNAMIC_FTRACE
struct event_probe_data {
        struct trace_event_file *file;
        unsigned long                   count;
        int                             ref;
        bool                            enable;
};

static void update_event_probe(struct event_probe_data *data)
{
        if (data->enable)
                clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &data->file->flags);
        else
                set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &data->file->flags);
}

static void
event_enable_probe(unsigned long ip, unsigned long parent_ip,
                   struct trace_array *tr, struct ftrace_probe_ops *ops,
                   void *data)
{
        struct ftrace_func_mapper *mapper = data;
        struct event_probe_data *edata;
        void **pdata;

        pdata = ftrace_func_mapper_find_ip(mapper, ip);
        if (!pdata || !*pdata)
                return;

        edata = *pdata;
        update_event_probe(edata);
}

static void
event_enable_count_probe(unsigned long ip, unsigned long parent_ip,
                         struct trace_array *tr, struct ftrace_probe_ops *ops,
                         void *data)
{
        struct ftrace_func_mapper *mapper = data;
        struct event_probe_data *edata;
        void **pdata;

        pdata = ftrace_func_mapper_find_ip(mapper, ip);
        if (!pdata || !*pdata)
                return;

        edata = *pdata;

        if (!edata->count)
                return;

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

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

        update_event_probe(edata);
}

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

        pdata = ftrace_func_mapper_find_ip(mapper, ip);

        if (WARN_ON_ONCE(!pdata || !*pdata))
                return 0;

        edata = *pdata;

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

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

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

        return 0;
}

static int
event_enable_init(struct ftrace_probe_ops *ops, struct trace_array *tr,
                  unsigned long ip, void *init_data, void **data)
{
        struct ftrace_func_mapper *mapper = *data;
        struct event_probe_data *edata = init_data;
        int ret;

        if (!mapper) {
                mapper = allocate_ftrace_func_mapper();
                if (!mapper)
                        return -ENODEV;
                *data = mapper;
        }

        ret = ftrace_func_mapper_add_ip(mapper, ip, edata);
        if (ret < 0)
                return ret;

        edata->ref++;

        return 0;
}

static int free_probe_data(void *data)
{
        struct event_probe_data *edata = data;

        edata->ref--;
        if (!edata->ref) {
                /* Remove soft mode */
                __ftrace_event_enable_disable(edata->file, 0, 1);
                trace_event_put_ref(edata->file->event_call);
                kfree(edata);
        }
        return 0;
}

static void
event_enable_free(struct ftrace_probe_ops *ops, struct trace_array *tr,
                  unsigned long ip, void *data)
{
        struct ftrace_func_mapper *mapper = data;
        struct event_probe_data *edata;

        if (!ip) {
                if (!mapper)
                        return;
                free_ftrace_func_mapper(mapper, free_probe_data);
                return;
        }

        edata = ftrace_func_mapper_remove_ip(mapper, ip);

        if (WARN_ON_ONCE(!edata))
                return;

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

        free_probe_data(edata);
}

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

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

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

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

static int
event_enable_func(struct trace_array *tr, struct ftrace_hash *hash,
                  char *glob, char *cmd, char *param, int enabled)
{
        struct trace_event_file *file;
        struct ftrace_probe_ops *ops;
        struct event_probe_data *data;
        unsigned long count = -1;
        const char *system;
        const char *event;
        char *number;
        bool enable;
        int ret;

        if (!tr)
                return -ENODEV;

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

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

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

        guard(mutex)(&event_mutex);

        file = find_event_file(tr, system, event);
        if (!file)
                return -EINVAL;

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

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

        if (glob[0] == '!')
                return unregister_ftrace_function_probe_func(glob+1, tr, ops);

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

                if (!strlen(number))
                        return -EINVAL;

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

        /* Don't let event modules unload while probe registered */
        ret = trace_event_try_get_ref(file->event_call);
        if (!ret)
                return -EBUSY;

        ret = __ftrace_event_enable_disable(file, 1, 1);
        if (ret < 0)
                goto out_put;

        ret = -ENOMEM;
        data = kzalloc_obj(*data);
        if (!data)
                goto out_put;

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

        ret = register_ftrace_function_probe(glob, tr, ops, data);
        /*
         * The above returns on success the # of functions enabled,
         * but if it didn't find any functions it returns zero.
         * Consider no functions a failure too.
         */

        /* Just return zero, not the number of enabled functions */
        if (ret > 0)
                return 0;

        kfree(data);

        if (!ret)
                ret = -ENOENT;

        __ftrace_event_enable_disable(file, 0, 1);
 out_put:
        trace_event_put_ref(file->event_call);
        return ret;
}

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

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

static __init int register_event_cmds(void)
{
        int ret;

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

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


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

/*
 * For early boot up, the top trace array and the trace arrays created
 * by boot-time tracing require 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.
 */
void __trace_early_add_events(struct trace_array *tr)
{
        struct trace_event_call *call;
        int ret;

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

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

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

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

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

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

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

static char bootup_event_buf[COMMAND_LINE_SIZE] __initdata;

static __init int setup_trace_event(char *str)
{
        if (bootup_event_buf[0] != '\0')
                strlcat(bootup_event_buf, ",", COMMAND_LINE_SIZE);

        strlcat(bootup_event_buf, str, COMMAND_LINE_SIZE);

        trace_set_ring_buffer_expanded(NULL);
        disable_tracing_selftest("running event tracing");

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

static int events_callback(const char *name, umode_t *mode, void **data,
                           const struct file_operations **fops)
{
        if (strcmp(name, "enable") == 0) {
                *mode = TRACE_MODE_WRITE;
                *fops = &ftrace_tr_enable_fops;
                return 1;
        }

        if (strcmp(name, "header_page") == 0) {
                *mode = TRACE_MODE_READ;
                *fops = &ftrace_show_header_page_fops;

        } else if (strcmp(name, "header_event") == 0) {
                *mode = TRACE_MODE_READ;
                *fops = &ftrace_show_header_event_fops;
        } else
                return 0;

        return 1;
}

/* Expects to have event_mutex held when called */
static int
create_event_toplevel_files(struct dentry *parent, struct trace_array *tr)
{
        struct eventfs_inode *e_events;
        struct dentry *entry;
        int nr_entries;
        static struct eventfs_entry events_entries[] = {
                {
                        .name           = "enable",
                        .callback       = events_callback,
                },
                {
                        .name           = "header_page",
                        .callback       = events_callback,
                },
                {
                        .name           = "header_event",
                        .callback       = events_callback,
                },
        };

        entry = trace_create_file("set_event", TRACE_MODE_WRITE, parent,
                                  tr, &ftrace_set_event_fops);
        if (!entry)
                return -ENOMEM;

        trace_create_file("show_event_filters", TRACE_MODE_READ, parent, tr,
                          &ftrace_show_event_filters_fops);

        trace_create_file("show_event_triggers", TRACE_MODE_READ, parent, tr,
                          &ftrace_show_event_triggers_fops);

        nr_entries = ARRAY_SIZE(events_entries);

        e_events = eventfs_create_events_dir("events", parent, events_entries,
                                             nr_entries, tr);
        if (IS_ERR(e_events)) {
                pr_warn("Could not create tracefs 'events' directory\n");
                return -ENOMEM;
        }

        /* There are not as crucial, just warn if they are not created */

        trace_create_file("set_event_pid", TRACE_MODE_WRITE, parent,
                          tr, &ftrace_set_event_pid_fops);

        trace_create_file("set_event_notrace_pid",
                          TRACE_MODE_WRITE, parent, tr,
                          &ftrace_set_event_notrace_pid_fops);

        tr->event_dir = e_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 hierarchy in the @parent/events directory.
 *
 * Returns 0 on success.
 *
 * Must be called with event_mutex held.
 */
int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr)
{
        int ret;

        lockdep_assert_held(&event_mutex);

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

        down_write(&trace_event_sem);
        /* If tr already has the event list, it is initialized in early boot. */
        if (unlikely(!list_empty(&tr->events)))
                __trace_early_add_event_dirs(tr);
        else
                __trace_add_event_dirs(tr);
        up_write(&trace_event_sem);

 out:
        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;

        guard(mutex)(&event_mutex);

        ret = create_event_toplevel_files(parent, tr);
        if (ret)
                return ret;

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

        return 0;
}

/* Must be called with event_mutex held */
int event_trace_del_tracer(struct trace_array *tr)
{
        lockdep_assert_held(&event_mutex);

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

        /* Clear the pid list */
        __ftrace_clear_event_pids(tr, TRACE_PIDS | TRACE_NO_PIDS);

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

        /* Make sure no more events are being executed */
        tracepoint_synchronize_unregister();

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

        tr->event_dir = NULL;

        return 0;
}

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

/*
 * Helper function to enable or disable a comma-separated list of events
 * from the bootup buffer.
 */
static __init void __early_set_events(struct trace_array *tr, char *buf, bool enable)
{
        char *token;

        while ((token = strsep(&buf, ","))) {
                if (*token) {
                        if (enable) {
                                if (ftrace_set_clr_event(tr, token, 1))
                                        pr_warn("Failed to enable trace event: %s\n", token);
                        } else {
                                ftrace_set_clr_event(tr, token, 0);
                        }
                }

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

/**
 * early_enable_events - enable events from the bootup buffer
 * @tr: The trace array to enable the events in
 * @buf: The buffer containing the comma separated list of events
 * @disable_first: If true, disable all events in @buf before enabling them
 *
 * This function enables events from the bootup buffer. If @disable_first
 * is true, it will first disable all events in the buffer before enabling
 * them.
 *
 * For syscall events, which rely on a global refcount to register the
 * SYSCALL_WORK_SYSCALL_TRACEPOINT flag (especially for pid 1), we must
 * ensure the refcount hits zero before re-enabling them. A simple
 * "disable then enable" per-event is not enough if multiple syscalls are
 * used, as the refcount will stay above zero. Thus, we need a two-phase
 * approach: disable all, then enable all.
 */
__init void
early_enable_events(struct trace_array *tr, char *buf, bool disable_first)
{
        if (disable_first)
                __early_set_events(tr, buf, false);

        __early_set_events(tr, buf, true);
}

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

        if (!tr)
                return -ENODEV;

        for_each_event(iter, __start_ftrace_events, __stop_ftrace_events) {

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

        register_trigger_cmds();

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

        early_enable_events(tr, bootup_event_buf, false);

        trace_printk_start_comm();

        register_event_cmds();


        return 0;
}

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

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

        early_enable_events(tr, bootup_event_buf, true);

        return 0;
}

early_initcall(event_trace_enable_again);

/* Init fields which doesn't related to the tracefs */
static __init int event_trace_init_fields(void)
{
        if (trace_define_generic_fields())
                pr_warn("tracing: Failed to allocated generic fields");

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

        return 0;
}

__init int event_trace_init(void)
{
        struct trace_array *tr;
        int ret;

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

        trace_create_file("available_events", TRACE_MODE_READ,
                          NULL, tr, &ftrace_avail_fops);

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

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

        eventdir_initialized = true;

        return 0;
}

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

#ifdef CONFIG_EVENT_TRACE_STARTUP_TEST

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

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

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

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

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

        schedule_on_each_cpu(test_work);

        kfree(test_malloc);

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

        return 0;
}

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

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

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

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

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

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

                call = file->event_call;

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

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

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

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

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

                pr_cont("OK\n");
        }

        /* Now test at the sub system level */

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

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

                system = dir->subsystem;

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

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

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

                event_test_stuff();

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

                pr_cont("OK\n");
        }

        /* Test with all events enabled */

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

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

        event_test_stuff();

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

        pr_cont("OK\n");
}

#ifdef CONFIG_FUNCTION_TRACER

static DEFINE_PER_CPU(atomic_t, ftrace_test_event_disable);

static struct trace_event_file event_trace_file __initdata;

static void __init
function_test_events_call(unsigned long ip, unsigned long parent_ip,
                          struct ftrace_ops *op, struct ftrace_regs *regs)
{
        struct trace_buffer *buffer;
        struct ring_buffer_event *event;
        struct ftrace_entry *entry;
        unsigned int trace_ctx;
        long disabled;
        int cpu;

        trace_ctx = tracing_gen_ctx();
        preempt_disable_notrace();
        cpu = raw_smp_processor_id();
        disabled = atomic_inc_return(&per_cpu(ftrace_test_event_disable, cpu));

        if (disabled != 1)
                goto out;

        event = trace_event_buffer_lock_reserve(&buffer, &event_trace_file,
                                                TRACE_FN, sizeof(*entry),
                                                trace_ctx);
        if (!event)
                goto out;
        entry   = ring_buffer_event_data(event);
        entry->ip                       = ip;
        entry->parent_ip                = parent_ip;

        event_trigger_unlock_commit(&event_trace_file, buffer, event,
                                    entry, trace_ctx);
 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,
};

static __init void event_trace_self_test_with_function(void)
{
        int ret;

        event_trace_file.tr = top_trace_array();
        if (WARN_ON(!event_trace_file.tr))
                return;

        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