// SPDX-License-Identifier: GPL-2.0-or-later

  /*

   * Copyright (C) 2008-2014 Mathieu Desnoyers

   */
  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/types.h>
  #include <linux/jhash.h>
  #include <linux/list.h>
  #include <linux/rcupdate.h>
  #include <linux/tracepoint.h>
  #include <linux/err.h>
  #include <linux/slab.h>

  #include <linux/sched/signal.h>

  #include <linux/sched/task.h>

  #include <linux/static_key.h>

  enum tp_func_state {
  	TP_FUNC_0,
  	TP_FUNC_1,
  	TP_FUNC_2,
  	TP_FUNC_N,
  };

  extern tracepoint_ptr_t __start___tracepoints_ptrs[];
  extern tracepoint_ptr_t __stop___tracepoints_ptrs[];

  DEFINE_SRCU(tracepoint_srcu);
  EXPORT_SYMBOL_GPL(tracepoint_srcu);

  enum tp_transition_sync {
  	TP_TRANSITION_SYNC_1_0_1,
  	TP_TRANSITION_SYNC_N_2_1,
  
  	_NR_TP_TRANSITION_SYNC,
  };
  
  struct tp_transition_snapshot {
  	unsigned long rcu;
  	unsigned long srcu;
  	bool ongoing;
  };
  
  /* Protected by tracepoints_mutex */
  static struct tp_transition_snapshot tp_transition_snapshot[_NR_TP_TRANSITION_SYNC];
  
  static void tp_rcu_get_state(enum tp_transition_sync sync)
  {
  	struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync];
  
  	/* Keep the latest get_state snapshot. */
  	snapshot->rcu = get_state_synchronize_rcu();
  	snapshot->srcu = start_poll_synchronize_srcu(&tracepoint_srcu);
  	snapshot->ongoing = true;
  }
  
  static void tp_rcu_cond_sync(enum tp_transition_sync sync)
  {
  	struct tp_transition_snapshot *snapshot = &tp_transition_snapshot[sync];
  
  	if (!snapshot->ongoing)
  		return;
  	cond_synchronize_rcu(snapshot->rcu);
  	if (!poll_state_synchronize_srcu(&tracepoint_srcu, snapshot->srcu))
  		synchronize_srcu(&tracepoint_srcu);
  	snapshot->ongoing = false;
  }

  /* Set to 1 to enable tracepoint debug output */
  static const int tracepoint_debug;

  #ifdef CONFIG_MODULES

  /*

   * Tracepoint module list mutex protects the local module list.

   */

  static DEFINE_MUTEX(tracepoint_module_list_mutex);

  /* Local list of struct tp_module */

  static LIST_HEAD(tracepoint_module_list);
  #endif /* CONFIG_MODULES */

  /*

   * tracepoints_mutex protects the builtin and module tracepoints.
   * tracepoints_mutex nests inside tracepoint_module_list_mutex.

   */

  static DEFINE_MUTEX(tracepoints_mutex);

  static struct rcu_head *early_probes;
  static bool ok_to_free_tracepoints;

  /*
   * Note about RCU :

   * It is used to delay the free of multiple probes array until a quiescent

   * state is reached.

   */

  struct tp_probes {

  	struct rcu_head rcu;

  	struct tracepoint_func probes[];

  };

  /* Called in removal of a func but failed to allocate a new tp_funcs */
  static void tp_stub_func(void)
  {
  	return;
  }

  static inline void *allocate_probes(int count)

  {

  	struct tp_probes *p  = kmalloc(struct_size(p, probes, count),
  				       GFP_KERNEL);

  	return p == NULL ? NULL : p->probes;

  }

  static void srcu_free_old_probes(struct rcu_head *head)

  {

  	kfree(container_of(head, struct tp_probes, rcu));

  }

  static void rcu_free_old_probes(struct rcu_head *head)
  {
  	call_srcu(&tracepoint_srcu, head, srcu_free_old_probes);
  }

  static __init int release_early_probes(void)
  {
  	struct rcu_head *tmp;
  
  	ok_to_free_tracepoints = true;
  
  	while (early_probes) {
  		tmp = early_probes;
  		early_probes = tmp->next;

  		call_rcu(tmp, rcu_free_old_probes);

  	}
  
  	return 0;
  }
  
  /* SRCU is initialized at core_initcall */
  postcore_initcall(release_early_probes);

  static inline void release_probes(struct tracepoint_func *old)

  {
  	if (old) {
  		struct tp_probes *tp_probes = container_of(old,
  			struct tp_probes, probes[0]);

  
  		/*
  		 * We can't free probes if SRCU is not initialized yet.
  		 * Postpone the freeing till after SRCU is initialized.
  		 */
  		if (unlikely(!ok_to_free_tracepoints)) {
  			tp_probes->rcu.next = early_probes;
  			early_probes = &tp_probes->rcu;
  			return;
  		}

  		/*
  		 * Tracepoint probes are protected by both sched RCU and SRCU,
  		 * by calling the SRCU callback in the sched RCU callback we
  		 * cover both cases. So let us chain the SRCU and sched RCU
  		 * callbacks to wait for both grace periods.
  		 */

  		call_rcu(&tp_probes->rcu, rcu_free_old_probes);

  	}

  }

  static void debug_print_probes(struct tracepoint_func *funcs)

  {
  	int i;

  	if (!tracepoint_debug || !funcs)

  		return;

  	for (i = 0; funcs[i].func; i++)
  		printk(KERN_DEBUG "Probe %d : %p
  ", i, funcs[i].func);

  }

  static struct tracepoint_func *
  func_add(struct tracepoint_func **funcs, struct tracepoint_func *tp_func,
  	 int prio)

  {

  	struct tracepoint_func *old, *new;

  	int iter_probes;	/* Iterate over old probe array. */
  	int nr_probes = 0;	/* Counter for probes */
  	int pos = -1;		/* Insertion position into new array */

  	if (WARN_ON(!tp_func->func))

  		return ERR_PTR(-EINVAL);

  	debug_print_probes(*funcs);
  	old = *funcs;

  	if (old) {
  		/* (N -> N+1), (N != 0, 1) probes */

  		for (iter_probes = 0; old[iter_probes].func; iter_probes++) {
  			if (old[iter_probes].func == tp_stub_func)
  				continue;	/* Skip stub functions. */
  			if (old[iter_probes].func == tp_func->func &&
  			    old[iter_probes].data == tp_func->data)

  				return ERR_PTR(-EEXIST);

  			nr_probes++;

  		}

  	}

  	/* + 2 : one for new probe, one for NULL func */
  	new = allocate_probes(nr_probes + 2);

  	if (new == NULL)
  		return ERR_PTR(-ENOMEM);

  	if (old) {

  		nr_probes = 0;
  		for (iter_probes = 0; old[iter_probes].func; iter_probes++) {
  			if (old[iter_probes].func == tp_stub_func)
  				continue;
  			/* Insert before probes of lower priority */
  			if (pos < 0 && old[iter_probes].prio < prio)
  				pos = nr_probes++;
  			new[nr_probes++] = old[iter_probes];

  		}

  		if (pos < 0)
  			pos = nr_probes++;
  		/* nr_probes now points to the end of the new array */
  	} else {

  		pos = 0;

  		nr_probes = 1; /* must point at end of array */
  	}

  	new[pos] = *tp_func;

  	new[nr_probes].func = NULL;

  	*funcs = new;
  	debug_print_probes(*funcs);

  	return old;
  }

  static void *func_remove(struct tracepoint_func **funcs,
  		struct tracepoint_func *tp_func)

  {
  	int nr_probes = 0, nr_del = 0, i;

  	struct tracepoint_func *old, *new;

  	old = *funcs;

  	if (!old)

  		return ERR_PTR(-ENOENT);

  	debug_print_probes(*funcs);

  	/* (N -> M), (N > 1, M >= 0) probes */

  	if (tp_func->func) {

  		for (nr_probes = 0; old[nr_probes].func; nr_probes++) {

  			if ((old[nr_probes].func == tp_func->func &&
  			     old[nr_probes].data == tp_func->data) ||
  			    old[nr_probes].func == tp_stub_func)

  				nr_del++;
  		}

  	}

  	/*
  	 * If probe is NULL, then nr_probes = nr_del = 0, and then the
  	 * entire entry will be removed.
  	 */

  	if (nr_probes - nr_del == 0) {
  		/* N -> 0, (N > 1) */

  		*funcs = NULL;
  		debug_print_probes(*funcs);

  		return old;
  	} else {
  		int j = 0;
  		/* N -> M, (N > 1, M > 0) */
  		/* + 1 for NULL */

  		new = allocate_probes(nr_probes - nr_del + 1);

  		if (new) {

  			for (i = 0; old[i].func; i++) {
  				if ((old[i].func != tp_func->func ||
  				     old[i].data != tp_func->data) &&
  				    old[i].func != tp_stub_func)

  					new[j++] = old[i];

  			}

  			new[nr_probes - nr_del].func = NULL;
  			*funcs = new;
  		} else {
  			/*
  			 * Failed to allocate, replace the old function
  			 * with calls to tp_stub_func.
  			 */

  			for (i = 0; old[i].func; i++) {

  				if (old[i].func == tp_func->func &&

  				    old[i].data == tp_func->data)
  					WRITE_ONCE(old[i].func, tp_stub_func);
  			}

  			*funcs = old;
  		}

  	}

  	debug_print_probes(*funcs);

  	return old;
  }

  /*
   * Count the number of functions (enum tp_func_state) in a tp_funcs array.
   */
  static enum tp_func_state nr_func_state(const struct tracepoint_func *tp_funcs)
  {
  	if (!tp_funcs)
  		return TP_FUNC_0;
  	if (!tp_funcs[1].func)
  		return TP_FUNC_1;
  	if (!tp_funcs[2].func)
  		return TP_FUNC_2;
  	return TP_FUNC_N;	/* 3 or more */
  }
  
  static void tracepoint_update_call(struct tracepoint *tp, struct tracepoint_func *tp_funcs)

  {
  	void *func = tp->iterator;
  
  	/* Synthetic events do not have static call sites */
  	if (!tp->static_call_key)
  		return;

  	if (nr_func_state(tp_funcs) == TP_FUNC_1)

  		func = tp_funcs[0].func;

  	__static_call_update(tp->static_call_key, tp->static_call_tramp, func);
  }

  /*

   * Add the probe function to a tracepoint.

   */

  static int tracepoint_add_func(struct tracepoint *tp,

  			       struct tracepoint_func *func, int prio,
  			       bool warn)

  {

  	struct tracepoint_func *old, *tp_funcs;

  	int ret;

  	if (tp->regfunc && !static_key_enabled(&tp->key)) {
  		ret = tp->regfunc();
  		if (ret < 0)
  			return ret;
  	}

  	tp_funcs = rcu_dereference_protected(tp->funcs,
  			lockdep_is_held(&tracepoints_mutex));

  	old = func_add(&tp_funcs, func, prio);

  	if (IS_ERR(old)) {

  		WARN_ON_ONCE(warn && PTR_ERR(old) != -ENOMEM);

  		return PTR_ERR(old);
  	}

  	/*

  	 * rcu_assign_pointer has as smp_store_release() which makes sure
  	 * that the new probe callbacks array is consistent before setting
  	 * a pointer to it.  This array is referenced by __DO_TRACE from
  	 * include/linux/tracepoint.h using rcu_dereference_sched().

  	 */

  	switch (nr_func_state(tp_funcs)) {
  	case TP_FUNC_1:		/* 0->1 */

  		/*
  		 * Make sure new static func never uses old data after a
  		 * 1->0->1 transition sequence.
  		 */
  		tp_rcu_cond_sync(TP_TRANSITION_SYNC_1_0_1);

  		/* Set static call to first function */
  		tracepoint_update_call(tp, tp_funcs);
  		/* Both iterator and static call handle NULL tp->funcs */
  		rcu_assign_pointer(tp->funcs, tp_funcs);
  		static_key_enable(&tp->key);
  		break;
  	case TP_FUNC_2:		/* 1->2 */
  		/* Set iterator static call */
  		tracepoint_update_call(tp, tp_funcs);
  		/*
  		 * Iterator callback installed before updating tp->funcs.
  		 * Requires ordering between RCU assign/dereference and
  		 * static call update/call.
  		 */

  		fallthrough;

  	case TP_FUNC_N:		/* N->N+1 (N>1) */
  		rcu_assign_pointer(tp->funcs, tp_funcs);

  		/*
  		 * Make sure static func never uses incorrect data after a
  		 * N->...->2->1 (N>1) transition sequence.
  		 */
  		if (tp_funcs[0].data != old[0].data)
  			tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);

  		break;
  	default:
  		WARN_ON_ONCE(1);
  		break;
  	}

  	release_probes(old);

  	return 0;

  }
  
  /*

   * Remove a probe function from a tracepoint.

   * Note: only waiting an RCU period after setting elem->call to the empty
   * function insures that the original callback is not used anymore. This insured
   * by preempt_disable around the call site.
   */

  static int tracepoint_remove_func(struct tracepoint *tp,
  		struct tracepoint_func *func)

  {

  	struct tracepoint_func *old, *tp_funcs;

  	tp_funcs = rcu_dereference_protected(tp->funcs,
  			lockdep_is_held(&tracepoints_mutex));

  	old = func_remove(&tp_funcs, func);

  	if (WARN_ON_ONCE(IS_ERR(old)))

  		return PTR_ERR(old);

  
  	if (tp_funcs == old)
  		/* Failed allocating new tp_funcs, replaced func with stub */
  		return 0;

  	switch (nr_func_state(tp_funcs)) {
  	case TP_FUNC_0:		/* 1->0 */

  		/* Removed last function */
  		if (tp->unregfunc && static_key_enabled(&tp->key))
  			tp->unregfunc();

  		static_key_disable(&tp->key);

  		/* Set iterator static call */
  		tracepoint_update_call(tp, tp_funcs);
  		/* Both iterator and static call handle NULL tp->funcs */
  		rcu_assign_pointer(tp->funcs, NULL);
  		/*

  		 * Make sure new static func never uses old data after a
  		 * 1->0->1 transition sequence.

  		 */

  		tp_rcu_get_state(TP_TRANSITION_SYNC_1_0_1);

  		break;
  	case TP_FUNC_1:		/* 2->1 */

  		rcu_assign_pointer(tp->funcs, tp_funcs);

  		/*

  		 * Make sure static func never uses incorrect data after a
  		 * N->...->2->1 (N>2) transition sequence. If the first
  		 * element's data has changed, then force the synchronization
  		 * to prevent current readers that have loaded the old data
  		 * from calling the new function.

  		 */

  		if (tp_funcs[0].data != old[0].data)
  			tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);
  		tp_rcu_cond_sync(TP_TRANSITION_SYNC_N_2_1);

  		/* Set static call to first function */
  		tracepoint_update_call(tp, tp_funcs);
  		break;
  	case TP_FUNC_2:		/* N->N-1 (N>2) */
  		fallthrough;
  	case TP_FUNC_N:

  		rcu_assign_pointer(tp->funcs, tp_funcs);

  		/*
  		 * Make sure static func never uses incorrect data after a
  		 * N->...->2->1 (N>2) transition sequence.
  		 */
  		if (tp_funcs[0].data != old[0].data)
  			tp_rcu_get_state(TP_TRANSITION_SYNC_N_2_1);

  		break;
  	default:
  		WARN_ON_ONCE(1);
  		break;

  	}

  	release_probes(old);

  	return 0;

  }

  /**

   * tracepoint_probe_register_prio_may_exist -  Connect a probe to a tracepoint with priority
   * @tp: tracepoint
   * @probe: probe handler
   * @data: tracepoint data
   * @prio: priority of this function over other registered functions
   *
   * Same as tracepoint_probe_register_prio() except that it will not warn
   * if the tracepoint is already registered.
   */
  int tracepoint_probe_register_prio_may_exist(struct tracepoint *tp, void *probe,
  					     void *data, int prio)
  {
  	struct tracepoint_func tp_func;
  	int ret;
  
  	mutex_lock(&tracepoints_mutex);
  	tp_func.func = probe;
  	tp_func.data = data;
  	tp_func.prio = prio;
  	ret = tracepoint_add_func(tp, &tp_func, prio, false);
  	mutex_unlock(&tracepoints_mutex);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio_may_exist);
  
  /**

   * tracepoint_probe_register_prio -  Connect a probe to a tracepoint with priority

   * @tp: tracepoint

   * @probe: probe handler

   * @data: tracepoint data

   * @prio: priority of this function over other registered functions

   *

   * Returns 0 if ok, error value on error.
   * Note: if @tp is within a module, the caller is responsible for
   * unregistering the probe before the module is gone. This can be
   * performed either with a tracepoint module going notifier, or from
   * within module exit functions.

   */

  int tracepoint_probe_register_prio(struct tracepoint *tp, void *probe,
  				   void *data, int prio)

  {

  	struct tracepoint_func tp_func;
  	int ret;

  
  	mutex_lock(&tracepoints_mutex);

  	tp_func.func = probe;
  	tp_func.data = data;

  	tp_func.prio = prio;

  	ret = tracepoint_add_func(tp, &tp_func, prio, true);

  	mutex_unlock(&tracepoints_mutex);

  	return ret;

  }

  EXPORT_SYMBOL_GPL(tracepoint_probe_register_prio);
  
  /**
   * tracepoint_probe_register -  Connect a probe to a tracepoint
   * @tp: tracepoint
   * @probe: probe handler
   * @data: tracepoint data

   *
   * Returns 0 if ok, error value on error.
   * Note: if @tp is within a module, the caller is responsible for
   * unregistering the probe before the module is gone. This can be
   * performed either with a tracepoint module going notifier, or from
   * within module exit functions.
   */
  int tracepoint_probe_register(struct tracepoint *tp, void *probe, void *data)
  {
  	return tracepoint_probe_register_prio(tp, probe, data, TRACEPOINT_DEFAULT_PRIO);
  }

  EXPORT_SYMBOL_GPL(tracepoint_probe_register);
  
  /**
   * tracepoint_probe_unregister -  Disconnect a probe from a tracepoint

   * @tp: tracepoint

   * @probe: probe function pointer

   * @data: tracepoint data

   *

   * Returns 0 if ok, error value on error.

   */

  int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data)

  {

  	struct tracepoint_func tp_func;
  	int ret;

  
  	mutex_lock(&tracepoints_mutex);

  	tp_func.func = probe;
  	tp_func.data = data;
  	ret = tracepoint_remove_func(tp, &tp_func);

  	mutex_unlock(&tracepoints_mutex);

  	return ret;

  }
  EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);

  static void for_each_tracepoint_range(
  		tracepoint_ptr_t *begin, tracepoint_ptr_t *end,

  		void (*fct)(struct tracepoint *tp, void *priv),
  		void *priv)
  {

  	tracepoint_ptr_t *iter;

  	if (!begin)
  		return;

  	for (iter = begin; iter < end; iter++)
  		fct(tracepoint_ptr_deref(iter), priv);

  }

  #ifdef CONFIG_MODULES

  bool trace_module_has_bad_taint(struct module *mod)
  {

  	return mod->taints & ~((1 << TAINT_OOT_MODULE) | (1 << TAINT_CRAP) |
  			       (1 << TAINT_UNSIGNED_MODULE));

  }

  static BLOCKING_NOTIFIER_HEAD(tracepoint_notify_list);
  
  /**

   * register_tracepoint_module_notifier - register tracepoint coming/going notifier

   * @nb: notifier block
   *
   * Notifiers registered with this function are called on module
   * coming/going with the tracepoint_module_list_mutex held.
   * The notifier block callback should expect a "struct tp_module" data
   * pointer.
   */
  int register_tracepoint_module_notifier(struct notifier_block *nb)
  {
  	struct tp_module *tp_mod;
  	int ret;
  
  	mutex_lock(&tracepoint_module_list_mutex);
  	ret = blocking_notifier_chain_register(&tracepoint_notify_list, nb);
  	if (ret)
  		goto end;
  	list_for_each_entry(tp_mod, &tracepoint_module_list, list)
  		(void) nb->notifier_call(nb, MODULE_STATE_COMING, tp_mod);
  end:
  	mutex_unlock(&tracepoint_module_list_mutex);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(register_tracepoint_module_notifier);
  
  /**

   * unregister_tracepoint_module_notifier - unregister tracepoint coming/going notifier

   * @nb: notifier block
   *
   * The notifier block callback should expect a "struct tp_module" data
   * pointer.
   */
  int unregister_tracepoint_module_notifier(struct notifier_block *nb)
  {
  	struct tp_module *tp_mod;
  	int ret;
  
  	mutex_lock(&tracepoint_module_list_mutex);
  	ret = blocking_notifier_chain_unregister(&tracepoint_notify_list, nb);
  	if (ret)
  		goto end;
  	list_for_each_entry(tp_mod, &tracepoint_module_list, list)
  		(void) nb->notifier_call(nb, MODULE_STATE_GOING, tp_mod);
  end:
  	mutex_unlock(&tracepoint_module_list_mutex);
  	return ret;
  
  }
  EXPORT_SYMBOL_GPL(unregister_tracepoint_module_notifier);
  
  /*
   * Ensure the tracer unregistered the module's probes before the module
   * teardown is performed. Prevents leaks of probe and data pointers.
   */

  static void tp_module_going_check_quiescent(struct tracepoint *tp, void *priv)

  {

  	WARN_ON_ONCE(tp->funcs);

  }

  static int tracepoint_module_coming(struct module *mod)
  {

  	struct tp_module *tp_mod;

  	int ret = 0;

  	if (!mod->num_tracepoints)
  		return 0;

  	/*

  	 * We skip modules that taint the kernel, especially those with different
  	 * module headers (for forced load), to make sure we don't cause a crash.

  	 * Staging, out-of-tree, and unsigned GPL modules are fine.

  	 */

  	if (trace_module_has_bad_taint(mod))

  		return 0;

  	mutex_lock(&tracepoint_module_list_mutex);

  	tp_mod = kmalloc(sizeof(struct tp_module), GFP_KERNEL);
  	if (!tp_mod) {
  		ret = -ENOMEM;
  		goto end;
  	}

  	tp_mod->mod = mod;

  	list_add_tail(&tp_mod->list, &tracepoint_module_list);

  	blocking_notifier_call_chain(&tracepoint_notify_list,
  			MODULE_STATE_COMING, tp_mod);

  end:

  	mutex_unlock(&tracepoint_module_list_mutex);

  	return ret;
  }

  static void tracepoint_module_going(struct module *mod)

  {

  	struct tp_module *tp_mod;

  	if (!mod->num_tracepoints)

  		return;

  	mutex_lock(&tracepoint_module_list_mutex);
  	list_for_each_entry(tp_mod, &tracepoint_module_list, list) {

  		if (tp_mod->mod == mod) {

  			blocking_notifier_call_chain(&tracepoint_notify_list,
  					MODULE_STATE_GOING, tp_mod);
  			list_del(&tp_mod->list);
  			kfree(tp_mod);
  			/*
  			 * Called the going notifier before checking for
  			 * quiescence.
  			 */

  			for_each_tracepoint_range(mod->tracepoints_ptrs,
  				mod->tracepoints_ptrs + mod->num_tracepoints,
  				tp_module_going_check_quiescent, NULL);

  			break;
  		}
  	}
  	/*
  	 * In the case of modules that were tainted at "coming", we'll simply
  	 * walk through the list without finding it. We cannot use the "tainted"
  	 * flag on "going", in case a module taints the kernel only after being
  	 * loaded.
  	 */

  	mutex_unlock(&tracepoint_module_list_mutex);

  }

  static int tracepoint_module_notify(struct notifier_block *self,
  		unsigned long val, void *data)

  {
  	struct module *mod = data;

  	int ret = 0;

  
  	switch (val) {
  	case MODULE_STATE_COMING:

  		ret = tracepoint_module_coming(mod);
  		break;
  	case MODULE_STATE_LIVE:
  		break;

  	case MODULE_STATE_GOING:

  		tracepoint_module_going(mod);
  		break;
  	case MODULE_STATE_UNFORMED:

  		break;
  	}

  	return notifier_from_errno(ret);

  }

  static struct notifier_block tracepoint_module_nb = {

  	.notifier_call = tracepoint_module_notify,
  	.priority = 0,
  };

  static __init int init_tracepoints(void)

  {

  	int ret;
  
  	ret = register_module_notifier(&tracepoint_module_nb);

  	if (ret)

  		pr_warn("Failed to register tracepoint module enter notifier
  ");

  	return ret;

  }
  __initcall(init_tracepoints);

  #endif /* CONFIG_MODULES */

  /**
   * for_each_kernel_tracepoint - iteration on all kernel tracepoints
   * @fct: callback
   * @priv: private data
   */
  void for_each_kernel_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
  		void *priv)
  {
  	for_each_tracepoint_range(__start___tracepoints_ptrs,
  		__stop___tracepoints_ptrs, fct, priv);
  }
  EXPORT_SYMBOL_GPL(for_each_kernel_tracepoint);

  #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS

  /* NB: reg/unreg are called while guarded with the tracepoints_mutex */

  static int sys_tracepoint_refcount;

  int syscall_regfunc(void)

  {

  	struct task_struct *p, *t;

  	if (!sys_tracepoint_refcount) {

  		read_lock(&tasklist_lock);
  		for_each_process_thread(p, t) {

  			set_task_syscall_work(t, SYSCALL_TRACEPOINT);

  		}
  		read_unlock(&tasklist_lock);

  	}
  	sys_tracepoint_refcount++;

  
  	return 0;

  }
  
  void syscall_unregfunc(void)
  {

  	struct task_struct *p, *t;

  	sys_tracepoint_refcount--;
  	if (!sys_tracepoint_refcount) {

  		read_lock(&tasklist_lock);
  		for_each_process_thread(p, t) {

  			clear_task_syscall_work(t, SYSCALL_TRACEPOINT);

  		}
  		read_unlock(&tasklist_lock);

  	}

  }

  #endif