// SPDX-License-Identifier: GPL-2.0
/*
 * ring buffer based function tracer
 *
 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
 *
 * Based on code from the latency_tracer, that is:
 *
 *  Copyright (C) 2004-2006 Ingo Molnar
 *  Copyright (C) 2004 Nadia Yvette Chambers
 */
#include <linux/ring_buffer.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/slab.h>
#include <linux/fs.h>

#include "trace.h"

static void tracing_start_function_trace(struct trace_array *tr);
static void tracing_stop_function_trace(struct trace_array *tr);
static void
function_trace_call(unsigned long ip, unsigned long parent_ip,
                    struct ftrace_ops *op, struct ftrace_regs *fregs);
static void
function_args_trace_call(unsigned long ip, unsigned long parent_ip,
                         struct ftrace_ops *op, struct ftrace_regs *fregs);
static void
function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
                          struct ftrace_ops *op, struct ftrace_regs *fregs);
static void
function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
                               struct ftrace_ops *op, struct ftrace_regs *fregs);
static void
function_stack_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
                                     struct ftrace_ops *op,
                                     struct ftrace_regs *fregs);
static struct tracer_flags func_flags;

/* Our option */
enum {

        TRACE_FUNC_NO_OPTS              = 0x0, /* No flags set. */
        TRACE_FUNC_OPT_STACK            = 0x1,
        TRACE_FUNC_OPT_NO_REPEATS       = 0x2,
        TRACE_FUNC_OPT_ARGS             = 0x4,

        /* Update this to next highest bit. */
        TRACE_FUNC_OPT_HIGHEST_BIT      = 0x8
};

#define TRACE_FUNC_OPT_MASK     (TRACE_FUNC_OPT_HIGHEST_BIT - 1)

int ftrace_allocate_ftrace_ops(struct trace_array *tr)
{
        struct ftrace_ops *ops;

        /* The top level array uses the "global_ops" */
        if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
                return 0;

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

        /* Currently only the non stack version is supported */
        ops->func = function_trace_call;
        ops->flags = FTRACE_OPS_FL_PID;

        tr->ops = ops;
        ops->private = tr;

        return 0;
}

void ftrace_free_ftrace_ops(struct trace_array *tr)
{
        kfree(tr->ops);
        tr->ops = NULL;
}

int ftrace_create_function_files(struct trace_array *tr,
                                 struct dentry *parent)
{
        int ret;
        /*
         * The top level array uses the "global_ops", and the files are
         * created on boot up.
         */
        if (tr->flags & TRACE_ARRAY_FL_GLOBAL)
                return 0;

        if (!tr->ops)
                return -EINVAL;

        ret = allocate_fgraph_ops(tr, tr->ops);
        if (ret) {
                kfree(tr->ops);
                return ret;
        }

        ftrace_create_filter_files(tr->ops, parent);

        return 0;
}

void ftrace_destroy_function_files(struct trace_array *tr)
{
        ftrace_destroy_filter_files(tr->ops);
        ftrace_free_ftrace_ops(tr);
        free_fgraph_ops(tr);
}

static ftrace_func_t select_trace_function(u32 flags_val)
{
        switch (flags_val & TRACE_FUNC_OPT_MASK) {
        case TRACE_FUNC_NO_OPTS:
                return function_trace_call;
        case TRACE_FUNC_OPT_ARGS:
                return function_args_trace_call;
        case TRACE_FUNC_OPT_STACK:
                return function_stack_trace_call;
        case TRACE_FUNC_OPT_NO_REPEATS:
                return function_no_repeats_trace_call;
        case TRACE_FUNC_OPT_STACK | TRACE_FUNC_OPT_NO_REPEATS:
                return function_stack_no_repeats_trace_call;
        default:
                return NULL;
        }
}

static bool handle_func_repeats(struct trace_array *tr, u32 flags_val)
{
        if (!tr->last_func_repeats &&
            (flags_val & TRACE_FUNC_OPT_NO_REPEATS)) {
                tr->last_func_repeats = alloc_percpu(struct trace_func_repeats);
                if (!tr->last_func_repeats)
                        return false;
        }

        return true;
}

static int function_trace_init(struct trace_array *tr)
{
        ftrace_func_t func;
        /*
         * Instance trace_arrays get their ops allocated
         * at instance creation. Unless it failed
         * the allocation.
         */
        if (!tr->ops)
                return -ENOMEM;

        func = select_trace_function(tr->current_trace_flags->val);
        if (!func)
                return -EINVAL;

        if (!handle_func_repeats(tr, tr->current_trace_flags->val))
                return -ENOMEM;

        ftrace_init_array_ops(tr, func);

        tr->array_buffer.cpu = raw_smp_processor_id();

        tracing_start_cmdline_record();
        tracing_start_function_trace(tr);
        return 0;
}

static void function_trace_reset(struct trace_array *tr)
{
        tracing_stop_function_trace(tr);
        tracing_stop_cmdline_record();
        ftrace_reset_array_ops(tr);
}

static void function_trace_start(struct trace_array *tr)
{
        tracing_reset_online_cpus(&tr->array_buffer);
}

/* fregs are guaranteed not to be NULL if HAVE_DYNAMIC_FTRACE_WITH_ARGS is set */
#if defined(CONFIG_FUNCTION_GRAPH_TRACER) && defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS)
static __always_inline unsigned long
function_get_true_parent_ip(unsigned long parent_ip, struct ftrace_regs *fregs)
{
        unsigned long true_parent_ip;
        int idx = 0;

        true_parent_ip = parent_ip;
        if (unlikely(parent_ip == (unsigned long)&return_to_handler) && fregs)
                true_parent_ip = ftrace_graph_ret_addr(current, &idx, parent_ip,
                                (unsigned long *)ftrace_regs_get_stack_pointer(fregs));
        return true_parent_ip;
}
#else
static __always_inline unsigned long
function_get_true_parent_ip(unsigned long parent_ip, struct ftrace_regs *fregs)
{
        return parent_ip;
}
#endif

static void
function_trace_call(unsigned long ip, unsigned long parent_ip,
                    struct ftrace_ops *op, struct ftrace_regs *fregs)
{
        struct trace_array *tr = op->private;
        unsigned int trace_ctx;
        int bit;

        if (unlikely(!tr->function_enabled))
                return;

        bit = ftrace_test_recursion_trylock(ip, parent_ip);
        if (bit < 0)
                return;

        parent_ip = function_get_true_parent_ip(parent_ip, fregs);

        trace_ctx = tracing_gen_ctx_dec();

        trace_function(tr, ip, parent_ip, trace_ctx, NULL);

        ftrace_test_recursion_unlock(bit);
}

static void
function_args_trace_call(unsigned long ip, unsigned long parent_ip,
                         struct ftrace_ops *op, struct ftrace_regs *fregs)
{
        struct trace_array *tr = op->private;
        unsigned int trace_ctx;
        int bit;

        if (unlikely(!tr->function_enabled))
                return;

        bit = ftrace_test_recursion_trylock(ip, parent_ip);
        if (bit < 0)
                return;

        trace_ctx = tracing_gen_ctx();

        trace_function(tr, ip, parent_ip, trace_ctx, fregs);

        ftrace_test_recursion_unlock(bit);
}

#ifdef CONFIG_UNWINDER_ORC
/*
 * Skip 2:
 *
 *   function_stack_trace_call()
 *   ftrace_call()
 */
#define STACK_SKIP 2
#else
/*
 * Skip 3:
 *   __trace_stack()
 *   function_stack_trace_call()
 *   ftrace_call()
 */
#define STACK_SKIP 3
#endif

static void
function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
                          struct ftrace_ops *op, struct ftrace_regs *fregs)
{
        struct trace_array *tr = op->private;
        struct trace_array_cpu *data;
        unsigned long flags;
        long disabled;
        int cpu;
        unsigned int trace_ctx;
        int skip = STACK_SKIP;

        if (unlikely(!tr->function_enabled))
                return;

        /*
         * Need to use raw, since this must be called before the
         * recursive protection is performed.
         */
        local_irq_save(flags);
        parent_ip = function_get_true_parent_ip(parent_ip, fregs);
        cpu = raw_smp_processor_id();
        data = per_cpu_ptr(tr->array_buffer.data, cpu);
        disabled = local_inc_return(&data->disabled);

        if (likely(disabled == 1)) {
                trace_ctx = tracing_gen_ctx_flags(flags);
                trace_function(tr, ip, parent_ip, trace_ctx, NULL);
#ifdef CONFIG_UNWINDER_FRAME_POINTER
                if (ftrace_pids_enabled(op))
                        skip++;
#endif
                __trace_stack(tr, trace_ctx, skip);
        }

        local_dec(&data->disabled);
        local_irq_restore(flags);
}

static inline bool is_repeat_check(struct trace_array *tr,
                                   struct trace_func_repeats *last_info,
                                   unsigned long ip, unsigned long parent_ip)
{
        if (last_info->ip == ip &&
            last_info->parent_ip == parent_ip &&
            last_info->count < U16_MAX) {
                last_info->ts_last_call =
                        ring_buffer_time_stamp(tr->array_buffer.buffer);
                last_info->count++;
                return true;
        }

        return false;
}

static inline void process_repeats(struct trace_array *tr,
                                   unsigned long ip, unsigned long parent_ip,
                                   struct trace_func_repeats *last_info,
                                   unsigned int trace_ctx)
{
        if (last_info->count) {
                trace_last_func_repeats(tr, last_info, trace_ctx);
                last_info->count = 0;
        }

        last_info->ip = ip;
        last_info->parent_ip = parent_ip;
}

static void
function_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
                               struct ftrace_ops *op,
                               struct ftrace_regs *fregs)
{
        struct trace_func_repeats *last_info;
        struct trace_array *tr = op->private;
        unsigned int trace_ctx;
        int bit;

        if (unlikely(!tr->function_enabled))
                return;

        bit = ftrace_test_recursion_trylock(ip, parent_ip);
        if (bit < 0)
                return;

        parent_ip = function_get_true_parent_ip(parent_ip, fregs);
        if (!tracer_tracing_is_on(tr))
                goto out;

        /*
         * An interrupt may happen at any place here. But as far as I can see,
         * the only damage that this can cause is to mess up the repetition
         * counter without valuable data being lost.
         * TODO: think about a solution that is better than just hoping to be
         * lucky.
         */
        last_info = this_cpu_ptr(tr->last_func_repeats);
        if (is_repeat_check(tr, last_info, ip, parent_ip))
                goto out;

        trace_ctx = tracing_gen_ctx_dec();
        process_repeats(tr, ip, parent_ip, last_info, trace_ctx);

        trace_function(tr, ip, parent_ip, trace_ctx, NULL);

out:
        ftrace_test_recursion_unlock(bit);
}

static void
function_stack_no_repeats_trace_call(unsigned long ip, unsigned long parent_ip,
                                     struct ftrace_ops *op,
                                     struct ftrace_regs *fregs)
{
        struct trace_func_repeats *last_info;
        struct trace_array *tr = op->private;
        struct trace_array_cpu *data;
        unsigned long flags;
        long disabled;
        int cpu;
        unsigned int trace_ctx;

        if (unlikely(!tr->function_enabled))
                return;

        /*
         * Need to use raw, since this must be called before the
         * recursive protection is performed.
         */
        local_irq_save(flags);
        parent_ip = function_get_true_parent_ip(parent_ip, fregs);
        cpu = raw_smp_processor_id();
        data = per_cpu_ptr(tr->array_buffer.data, cpu);
        disabled = local_inc_return(&data->disabled);

        if (likely(disabled == 1)) {
                last_info = per_cpu_ptr(tr->last_func_repeats, cpu);
                if (is_repeat_check(tr, last_info, ip, parent_ip))
                        goto out;

                trace_ctx = tracing_gen_ctx_flags(flags);
                process_repeats(tr, ip, parent_ip, last_info, trace_ctx);

                trace_function(tr, ip, parent_ip, trace_ctx, NULL);
                __trace_stack(tr, trace_ctx, STACK_SKIP);
        }

 out:
        local_dec(&data->disabled);
        local_irq_restore(flags);
}

static struct tracer_opt func_opts[] = {
#ifdef CONFIG_STACKTRACE
        { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
#endif
        { TRACER_OPT(func-no-repeats, TRACE_FUNC_OPT_NO_REPEATS) },
#ifdef CONFIG_FUNCTION_TRACE_ARGS
        { TRACER_OPT(func-args, TRACE_FUNC_OPT_ARGS) },
#endif
        { } /* Always set a last empty entry */
};

static struct tracer_flags func_flags = {
        .val = TRACE_FUNC_NO_OPTS, /* By default: all flags disabled */
        .opts = func_opts
};

static void tracing_start_function_trace(struct trace_array *tr)
{
        tr->function_enabled = 0;
        register_ftrace_function(tr->ops);
        tr->function_enabled = 1;
}

static void tracing_stop_function_trace(struct trace_array *tr)
{
        tr->function_enabled = 0;
        unregister_ftrace_function(tr->ops);
}

static struct tracer function_trace;

static int
func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set)
{
        ftrace_func_t func;
        u32 new_flags;

        /* Do nothing if already set. */
        if (!!set == !!(tr->current_trace_flags->val & bit))
                return 0;

        /* We can change this flag only when not running. */
        if (tr->current_trace != &function_trace)
                return 0;

        new_flags = (tr->current_trace_flags->val & ~bit) | (set ? bit : 0);
        func = select_trace_function(new_flags);
        if (!func)
                return -EINVAL;

        /* Check if there's anything to change. */
        if (tr->ops->func == func)
                return 0;

        if (!handle_func_repeats(tr, new_flags))
                return -ENOMEM;

        unregister_ftrace_function(tr->ops);
        tr->ops->func = func;
        register_ftrace_function(tr->ops);

        return 0;
}

static struct tracer function_trace __tracer_data =
{
        .name           = "function",
        .init           = function_trace_init,
        .reset          = function_trace_reset,
        .start          = function_trace_start,
        .default_flags  = &func_flags,
        .set_flag       = func_set_flag,
        .allow_instances = true,
#ifdef CONFIG_FTRACE_SELFTEST
        .selftest       = trace_selftest_startup_function,
#endif
};

#ifdef CONFIG_DYNAMIC_FTRACE
static void update_traceon_count(struct ftrace_probe_ops *ops,
                                 unsigned long ip,
                                 struct trace_array *tr, bool on,
                                 void *data)
{
        struct ftrace_func_mapper *mapper = data;
        long *count;
        long old_count;

        /*
         * Tracing gets disabled (or enabled) once per count.
         * This function can be called at the same time on multiple CPUs.
         * It is fine if both disable (or enable) tracing, as disabling
         * (or enabling) the second time doesn't do anything as the
         * state of the tracer is already disabled (or enabled).
         * What needs to be synchronized in this case is that the count
         * only gets decremented once, even if the tracer is disabled
         * (or enabled) twice, as the second one is really a nop.
         *
         * The memory barriers guarantee that we only decrement the
         * counter once. First the count is read to a local variable
         * and a read barrier is used to make sure that it is loaded
         * before checking if the tracer is in the state we want.
         * If the tracer is not in the state we want, then the count
         * is guaranteed to be the old count.
         *
         * Next the tracer is set to the state we want (disabled or enabled)
         * then a write memory barrier is used to make sure that
         * the new state is visible before changing the counter by
         * one minus the old counter. This guarantees that another CPU
         * executing this code will see the new state before seeing
         * the new counter value, and would not do anything if the new
         * counter is seen.
         *
         * Note, there is no synchronization between this and a user
         * setting the tracing_on file. But we currently don't care
         * about that.
         */
        count = (long *)ftrace_func_mapper_find_ip(mapper, ip);
        old_count = *count;

        if (old_count <= 0)
                return;

        /* Make sure we see count before checking tracing state */
        smp_rmb();

        if (on == !!tracer_tracing_is_on(tr))
                return;

        if (on)
                tracer_tracing_on(tr);
        else
                tracer_tracing_off(tr);

        /* Make sure tracing state is visible before updating count */
        smp_wmb();

        *count = old_count - 1;
}

static void
ftrace_traceon_count(unsigned long ip, unsigned long parent_ip,
                     struct trace_array *tr, struct ftrace_probe_ops *ops,
                     void *data)
{
        update_traceon_count(ops, ip, tr, 1, data);
}

static void
ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip,
                      struct trace_array *tr, struct ftrace_probe_ops *ops,
                      void *data)
{
        update_traceon_count(ops, ip, tr, 0, data);
}

static void
ftrace_traceon(unsigned long ip, unsigned long parent_ip,
               struct trace_array *tr, struct ftrace_probe_ops *ops,
               void *data)
{
        if (tracer_tracing_is_on(tr))
                return;

        tracer_tracing_on(tr);
}

static void
ftrace_traceoff(unsigned long ip, unsigned long parent_ip,
                struct trace_array *tr, struct ftrace_probe_ops *ops,
                void *data)
{
        if (!tracer_tracing_is_on(tr))
                return;

        tracer_tracing_off(tr);
}

#ifdef CONFIG_UNWINDER_ORC
/*
 * Skip 3:
 *
 *   function_trace_probe_call()
 *   ftrace_ops_assist_func()
 *   ftrace_call()
 */
#define FTRACE_STACK_SKIP 3
#else
/*
 * Skip 5:
 *
 *   __trace_stack()
 *   ftrace_stacktrace()
 *   function_trace_probe_call()
 *   ftrace_ops_assist_func()
 *   ftrace_call()
 */
#define FTRACE_STACK_SKIP 5
#endif

static __always_inline void trace_stack(struct trace_array *tr)
{
        __trace_stack(tr, tracing_gen_ctx_dec(), FTRACE_STACK_SKIP);
}

static void
ftrace_stacktrace(unsigned long ip, unsigned long parent_ip,
                  struct trace_array *tr, struct ftrace_probe_ops *ops,
                  void *data)
{
        trace_stack(tr);
}

static void
ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip,
                        struct trace_array *tr, struct ftrace_probe_ops *ops,
                        void *data)
{
        struct ftrace_func_mapper *mapper = data;
        long *count;
        long old_count;
        long new_count;

        if (!tracing_is_on())
                return;

        /* unlimited? */
        if (!mapper) {
                trace_stack(tr);
                return;
        }

        count = (long *)ftrace_func_mapper_find_ip(mapper, ip);

        /*
         * Stack traces should only execute the number of times the
         * user specified in the counter.
         */
        do {
                old_count = *count;

                if (!old_count)
                        return;

                new_count = old_count - 1;
                new_count = cmpxchg(count, old_count, new_count);
                if (new_count == old_count)
                        trace_stack(tr);

                if (!tracing_is_on())
                        return;

        } while (new_count != old_count);
}

static int update_count(struct ftrace_probe_ops *ops, unsigned long ip,
                        void *data)
{
        struct ftrace_func_mapper *mapper = data;
        long *count = NULL;

        if (mapper)
                count = (long *)ftrace_func_mapper_find_ip(mapper, ip);

        if (count) {
                if (*count <= 0)
                        return 0;
                (*count)--;
        }

        return 1;
}

static void
ftrace_dump_probe(unsigned long ip, unsigned long parent_ip,
                  struct trace_array *tr, struct ftrace_probe_ops *ops,
                  void *data)
{
        if (update_count(ops, ip, data))
                ftrace_dump(DUMP_ALL);
}

/* Only dump the current CPU buffer. */
static void
ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip,
                     struct trace_array *tr, struct ftrace_probe_ops *ops,
                     void *data)
{
        if (update_count(ops, ip, data))
                ftrace_dump(DUMP_ORIG);
}

static int
ftrace_probe_print(const char *name, struct seq_file *m,
                   unsigned long ip, struct ftrace_probe_ops *ops,
                   void *data)
{
        struct ftrace_func_mapper *mapper = data;
        long *count = NULL;

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

        if (mapper)
                count = (long *)ftrace_func_mapper_find_ip(mapper, ip);

        if (count)
                seq_printf(m, ":count=%ld\n", *count);
        else
                seq_puts(m, ":unlimited\n");

        return 0;
}

static int
ftrace_traceon_print(struct seq_file *m, unsigned long ip,
                     struct ftrace_probe_ops *ops,
                     void *data)
{
        return ftrace_probe_print("traceon", m, ip, ops, data);
}

static int
ftrace_traceoff_print(struct seq_file *m, unsigned long ip,
                         struct ftrace_probe_ops *ops, void *data)
{
        return ftrace_probe_print("traceoff", m, ip, ops, data);
}

static int
ftrace_stacktrace_print(struct seq_file *m, unsigned long ip,
                        struct ftrace_probe_ops *ops, void *data)
{
        return ftrace_probe_print("stacktrace", m, ip, ops, data);
}

static int
ftrace_dump_print(struct seq_file *m, unsigned long ip,
                        struct ftrace_probe_ops *ops, void *data)
{
        return ftrace_probe_print("dump", m, ip, ops, data);
}

static int
ftrace_cpudump_print(struct seq_file *m, unsigned long ip,
                        struct ftrace_probe_ops *ops, void *data)
{
        return ftrace_probe_print("cpudump", m, ip, ops, data);
}


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

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

        return ftrace_func_mapper_add_ip(mapper, ip, init_data);
}

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

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

        ftrace_func_mapper_remove_ip(mapper, ip);
}

static struct ftrace_probe_ops traceon_count_probe_ops = {
        .func                   = ftrace_traceon_count,
        .print                  = ftrace_traceon_print,
        .init                   = ftrace_count_init,
        .free                   = ftrace_count_free,
};

static struct ftrace_probe_ops traceoff_count_probe_ops = {
        .func                   = ftrace_traceoff_count,
        .print                  = ftrace_traceoff_print,
        .init                   = ftrace_count_init,
        .free                   = ftrace_count_free,
};

static struct ftrace_probe_ops stacktrace_count_probe_ops = {
        .func                   = ftrace_stacktrace_count,
        .print                  = ftrace_stacktrace_print,
        .init                   = ftrace_count_init,
        .free                   = ftrace_count_free,
};

static struct ftrace_probe_ops dump_probe_ops = {
        .func                   = ftrace_dump_probe,
        .print                  = ftrace_dump_print,
        .init                   = ftrace_count_init,
        .free                   = ftrace_count_free,
};

static struct ftrace_probe_ops cpudump_probe_ops = {
        .func                   = ftrace_cpudump_probe,
        .print                  = ftrace_cpudump_print,
};

static struct ftrace_probe_ops traceon_probe_ops = {
        .func                   = ftrace_traceon,
        .print                  = ftrace_traceon_print,
};

static struct ftrace_probe_ops traceoff_probe_ops = {
        .func                   = ftrace_traceoff,
        .print                  = ftrace_traceoff_print,
};

static struct ftrace_probe_ops stacktrace_probe_ops = {
        .func                   = ftrace_stacktrace,
        .print                  = ftrace_stacktrace_print,
};

static int
ftrace_trace_probe_callback(struct trace_array *tr,
                            struct ftrace_probe_ops *ops,
                            struct ftrace_hash *hash, char *glob,
                            char *cmd, char *param, int enable)
{
        void *count = (void *)-1;
        char *number;
        int ret;

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

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

        if (!param)
                goto out_reg;

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

        if (!strlen(number))
                goto out_reg;

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

 out_reg:
        ret = register_ftrace_function_probe(glob, tr, ops, count);

        return ret < 0 ? ret : 0;
}

static int
ftrace_trace_onoff_callback(struct trace_array *tr, struct ftrace_hash *hash,
                            char *glob, char *cmd, char *param, int enable)
{
        struct ftrace_probe_ops *ops;

        if (!tr)
                return -ENODEV;

        /* we register both traceon and traceoff to this callback */
        if (strcmp(cmd, "traceon") == 0)
                ops = param ? &traceon_count_probe_ops : &traceon_probe_ops;
        else
                ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops;

        return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
                                           param, enable);
}

static int
ftrace_stacktrace_callback(struct trace_array *tr, struct ftrace_hash *hash,
                           char *glob, char *cmd, char *param, int enable)
{
        struct ftrace_probe_ops *ops;

        if (!tr)
                return -ENODEV;

        ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops;

        return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
                                           param, enable);
}

static int
ftrace_dump_callback(struct trace_array *tr, struct ftrace_hash *hash,
                           char *glob, char *cmd, char *param, int enable)
{
        struct ftrace_probe_ops *ops;

        if (!tr)
                return -ENODEV;

        ops = &dump_probe_ops;

        /* Only dump once. */
        return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
                                           "1", enable);
}

static int
ftrace_cpudump_callback(struct trace_array *tr, struct ftrace_hash *hash,
                           char *glob, char *cmd, char *param, int enable)
{
        struct ftrace_probe_ops *ops;

        if (!tr)
                return -ENODEV;

        ops = &cpudump_probe_ops;

        /* Only dump once. */
        return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd,
                                           "1", enable);
}

static struct ftrace_func_command ftrace_traceon_cmd = {
        .name                   = "traceon",
        .func                   = ftrace_trace_onoff_callback,
};

static struct ftrace_func_command ftrace_traceoff_cmd = {
        .name                   = "traceoff",
        .func                   = ftrace_trace_onoff_callback,
};

static struct ftrace_func_command ftrace_stacktrace_cmd = {
        .name                   = "stacktrace",
        .func                   = ftrace_stacktrace_callback,
};

static struct ftrace_func_command ftrace_dump_cmd = {
        .name                   = "dump",
        .func                   = ftrace_dump_callback,
};

static struct ftrace_func_command ftrace_cpudump_cmd = {
        .name                   = "cpudump",
        .func                   = ftrace_cpudump_callback,
};

static int __init init_func_cmd_traceon(void)
{
        int ret;

        ret = register_ftrace_command(&ftrace_traceoff_cmd);
        if (ret)
                return ret;

        ret = register_ftrace_command(&ftrace_traceon_cmd);
        if (ret)
                goto out_free_traceoff;

        ret = register_ftrace_command(&ftrace_stacktrace_cmd);
        if (ret)
                goto out_free_traceon;

        ret = register_ftrace_command(&ftrace_dump_cmd);
        if (ret)
                goto out_free_stacktrace;

        ret = register_ftrace_command(&ftrace_cpudump_cmd);
        if (ret)
                goto out_free_dump;

        return 0;

 out_free_dump:
        unregister_ftrace_command(&ftrace_dump_cmd);
 out_free_stacktrace:
        unregister_ftrace_command(&ftrace_stacktrace_cmd);
 out_free_traceon:
        unregister_ftrace_command(&ftrace_traceon_cmd);
 out_free_traceoff:
        unregister_ftrace_command(&ftrace_traceoff_cmd);

        return ret;
}
#else
static inline int init_func_cmd_traceon(void)
{
        return 0;
}
#endif /* CONFIG_DYNAMIC_FTRACE */

__init int init_function_trace(void)
{
        init_func_cmd_traceon();
        return register_tracer(&function_trace);
}