/*
   * Infrastructure for profiling code inserted by 'gcc -pg'.
   *
   * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
   * Copyright (C) 2004-2008 Ingo Molnar <mingo@redhat.com>
   *
   * Originally ported from the -rt patch by:
   *   Copyright (C) 2007 Arnaldo Carvalho de Melo <acme@redhat.com>
   *
   * Based on code in the latency_tracer, that is:
   *
   *  Copyright (C) 2004-2006 Ingo Molnar
   *  Copyright (C) 2004 William Lee Irwin III
   */

  #include <linux/stop_machine.h>
  #include <linux/clocksource.h>
  #include <linux/kallsyms.h>

  #include <linux/seq_file.h>

  #include <linux/suspend.h>

  #include <linux/debugfs.h>

  #include <linux/hardirq.h>

  #include <linux/kthread.h>

  #include <linux/uaccess.h>

  #include <linux/bsearch.h>

  #include <linux/module.h>

  #include <linux/ftrace.h>

  #include <linux/sysctl.h>

  #include <linux/slab.h>

  #include <linux/ctype.h>

  #include <linux/sort.h>

  #include <linux/list.h>

  #include <linux/hash.h>

  #include <linux/rcupdate.h>

  #include <trace/events/sched.h>

  #include <asm/setup.h>

  #include "trace_output.h"

  #include "trace_stat.h"

  #define FTRACE_WARN_ON(cond)			\

  	({					\
  		int ___r = cond;		\
  		if (WARN_ON(___r))		\

  			ftrace_kill();		\

  		___r;				\
  	})

  
  #define FTRACE_WARN_ON_ONCE(cond)		\

  	({					\
  		int ___r = cond;		\
  		if (WARN_ON_ONCE(___r))		\

  			ftrace_kill();		\

  		___r;				\
  	})

  /* hash bits for specific function selection */
  #define FTRACE_HASH_BITS 7
  #define FTRACE_FUNC_HASHSIZE (1 << FTRACE_HASH_BITS)

  #define FTRACE_HASH_DEFAULT_BITS 10
  #define FTRACE_HASH_MAX_BITS 12

  /* ftrace_enabled is a method to turn ftrace on or off */
  int ftrace_enabled __read_mostly;

  static int last_ftrace_enabled;

  /* Quick disabling of function tracer. */
  int function_trace_stop;

  /* List for set_ftrace_pid's pids. */
  LIST_HEAD(ftrace_pids);
  struct ftrace_pid {
  	struct list_head list;
  	struct pid *pid;
  };

  /*
   * ftrace_disabled is set when an anomaly is discovered.
   * ftrace_disabled is much stronger than ftrace_enabled.
   */
  static int ftrace_disabled __read_mostly;

  static DEFINE_MUTEX(ftrace_lock);

  static struct ftrace_ops ftrace_list_end __read_mostly = {

  	.func		= ftrace_stub,

  };

  static struct ftrace_ops *ftrace_global_list __read_mostly = &ftrace_list_end;
  static struct ftrace_ops *ftrace_ops_list __read_mostly = &ftrace_list_end;

  ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;

  static ftrace_func_t __ftrace_trace_function_delay __read_mostly = ftrace_stub;

  ftrace_func_t __ftrace_trace_function __read_mostly = ftrace_stub;

  ftrace_func_t ftrace_pid_function __read_mostly = ftrace_stub;

  static struct ftrace_ops global_ops;

  static void
  ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip);

  /*

   * Traverse the ftrace_global_list, invoking all entries.  The reason that we

   * can use rcu_dereference_raw() is that elements removed from this list
   * are simply leaked, so there is no need to interact with a grace-period
   * mechanism.  The rcu_dereference_raw() calls are needed to handle

   * concurrent insertions into the ftrace_global_list.

   *
   * Silly Alpha and silly pointer-speculation compiler optimizations!
   */

  static void ftrace_global_list_func(unsigned long ip,
  				    unsigned long parent_ip)

  {

  	struct ftrace_ops *op;
  
  	if (unlikely(trace_recursion_test(TRACE_GLOBAL_BIT)))
  		return;

  	trace_recursion_set(TRACE_GLOBAL_BIT);
  	op = rcu_dereference_raw(ftrace_global_list); /*see above*/

  	while (op != &ftrace_list_end) {

  		op->func(ip, parent_ip);

  		op = rcu_dereference_raw(op->next); /*see above*/

  	};

  	trace_recursion_clear(TRACE_GLOBAL_BIT);

  }

  static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip)
  {

  	if (!test_tsk_trace_trace(current))

  		return;
  
  	ftrace_pid_function(ip, parent_ip);
  }
  
  static void set_ftrace_pid_function(ftrace_func_t func)
  {
  	/* do not set ftrace_pid_function to itself! */
  	if (func != ftrace_pid_func)
  		ftrace_pid_function = func;
  }

  /**

   * clear_ftrace_function - reset the ftrace function

   *

   * This NULLs the ftrace function and in essence stops
   * tracing.  There may be lag

   */

  void clear_ftrace_function(void)

  {

  	ftrace_trace_function = ftrace_stub;

  	__ftrace_trace_function = ftrace_stub;

  	__ftrace_trace_function_delay = ftrace_stub;

  	ftrace_pid_function = ftrace_stub;

  }

  #ifndef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
  /*
   * For those archs that do not test ftrace_trace_stop in their
   * mcount call site, we need to do it from C.
   */
  static void ftrace_test_stop_func(unsigned long ip, unsigned long parent_ip)
  {
  	if (function_trace_stop)
  		return;
  
  	__ftrace_trace_function(ip, parent_ip);
  }
  #endif

  static void update_global_ops(void)

  {
  	ftrace_func_t func;
  
  	/*
  	 * If there's only one function registered, then call that
  	 * function directly. Otherwise, we need to iterate over the
  	 * registered callers.
  	 */

  	if (ftrace_global_list == &ftrace_list_end ||
  	    ftrace_global_list->next == &ftrace_list_end)
  		func = ftrace_global_list->func;

  	else

  		func = ftrace_global_list_func;

  
  	/* If we filter on pids, update to use the pid function */
  	if (!list_empty(&ftrace_pids)) {
  		set_ftrace_pid_function(func);
  		func = ftrace_pid_func;
  	}

  
  	global_ops.func = func;
  }
  
  static void update_ftrace_function(void)
  {
  	ftrace_func_t func;
  
  	update_global_ops();

  	/*
  	 * If we are at the end of the list and this ops is
  	 * not dynamic, then have the mcount trampoline call
  	 * the function directly
  	 */

  	if (ftrace_ops_list == &ftrace_list_end ||

  	    (ftrace_ops_list->next == &ftrace_list_end &&
  	     !(ftrace_ops_list->flags & FTRACE_OPS_FL_DYNAMIC)))

  		func = ftrace_ops_list->func;
  	else
  		func = ftrace_ops_list_func;

  #ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
  	ftrace_trace_function = func;
  #else

  #ifdef CONFIG_DYNAMIC_FTRACE
  	/* do not update till all functions have been modified */
  	__ftrace_trace_function_delay = func;
  #else

  	__ftrace_trace_function = func;

  #endif

  	ftrace_trace_function = ftrace_test_stop_func;
  #endif
  }

  static void add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)

  {

  	ops->next = *list;

  	/*

  	 * We are entering ops into the list but another

  	 * CPU might be walking that list. We need to make sure
  	 * the ops->next pointer is valid before another CPU sees

  	 * the ops pointer included into the list.

  	 */

  	rcu_assign_pointer(*list, ops);

  }

  static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)

  {

  	struct ftrace_ops **p;

  
  	/*

  	 * If we are removing the last function, then simply point
  	 * to the ftrace_stub.

  	 */

  	if (*list == ops && ops->next == &ftrace_list_end) {
  		*list = &ftrace_list_end;

  		return 0;

  	}

  	for (p = list; *p != &ftrace_list_end; p = &(*p)->next)

  		if (*p == ops)
  			break;

  	if (*p != ops)
  		return -1;

  
  	*p = (*p)->next;

  	return 0;
  }

  static int __register_ftrace_function(struct ftrace_ops *ops)
  {
  	if (ftrace_disabled)
  		return -ENODEV;
  
  	if (FTRACE_WARN_ON(ops == &global_ops))
  		return -EINVAL;

  	if (WARN_ON(ops->flags & FTRACE_OPS_FL_ENABLED))
  		return -EBUSY;

  	if (!core_kernel_data((unsigned long)ops))
  		ops->flags |= FTRACE_OPS_FL_DYNAMIC;

  	if (ops->flags & FTRACE_OPS_FL_GLOBAL) {
  		int first = ftrace_global_list == &ftrace_list_end;
  		add_ftrace_ops(&ftrace_global_list, ops);
  		ops->flags |= FTRACE_OPS_FL_ENABLED;
  		if (first)
  			add_ftrace_ops(&ftrace_ops_list, &global_ops);
  	} else
  		add_ftrace_ops(&ftrace_ops_list, ops);

  	if (ftrace_enabled)
  		update_ftrace_function();
  
  	return 0;
  }
  
  static int __unregister_ftrace_function(struct ftrace_ops *ops)
  {
  	int ret;
  
  	if (ftrace_disabled)
  		return -ENODEV;

  	if (WARN_ON(!(ops->flags & FTRACE_OPS_FL_ENABLED)))
  		return -EBUSY;

  	if (FTRACE_WARN_ON(ops == &global_ops))
  		return -EINVAL;

  	if (ops->flags & FTRACE_OPS_FL_GLOBAL) {
  		ret = remove_ftrace_ops(&ftrace_global_list, ops);
  		if (!ret && ftrace_global_list == &ftrace_list_end)
  			ret = remove_ftrace_ops(&ftrace_ops_list, &global_ops);
  		if (!ret)
  			ops->flags &= ~FTRACE_OPS_FL_ENABLED;
  	} else
  		ret = remove_ftrace_ops(&ftrace_ops_list, ops);

  	if (ret < 0)
  		return ret;

  	if (ftrace_enabled)
  		update_ftrace_function();

  	/*
  	 * Dynamic ops may be freed, we must make sure that all
  	 * callers are done before leaving this function.
  	 */
  	if (ops->flags & FTRACE_OPS_FL_DYNAMIC)
  		synchronize_sched();

  	return 0;

  }

  static void ftrace_update_pid_func(void)
  {

  	/* Only do something if we are tracing something */

  	if (ftrace_trace_function == ftrace_stub)

  		return;

  	update_ftrace_function();

  }

  #ifdef CONFIG_FUNCTION_PROFILER
  struct ftrace_profile {
  	struct hlist_node		node;
  	unsigned long			ip;
  	unsigned long			counter;

  #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  	unsigned long long		time;

  	unsigned long long		time_squared;

  #endif

  };

  struct ftrace_profile_page {
  	struct ftrace_profile_page	*next;
  	unsigned long			index;
  	struct ftrace_profile		records[];

  };

  struct ftrace_profile_stat {
  	atomic_t			disabled;
  	struct hlist_head		*hash;
  	struct ftrace_profile_page	*pages;
  	struct ftrace_profile_page	*start;
  	struct tracer_stat		stat;
  };

  #define PROFILE_RECORDS_SIZE						\
  	(PAGE_SIZE - offsetof(struct ftrace_profile_page, records))

  #define PROFILES_PER_PAGE					\
  	(PROFILE_RECORDS_SIZE / sizeof(struct ftrace_profile))

  static int ftrace_profile_bits __read_mostly;
  static int ftrace_profile_enabled __read_mostly;
  
  /* ftrace_profile_lock - synchronize the enable and disable of the profiler */

  static DEFINE_MUTEX(ftrace_profile_lock);

  static DEFINE_PER_CPU(struct ftrace_profile_stat, ftrace_profile_stats);

  
  #define FTRACE_PROFILE_HASH_SIZE 1024 /* must be power of 2 */

  static void *
  function_stat_next(void *v, int idx)
  {

  	struct ftrace_profile *rec = v;
  	struct ftrace_profile_page *pg;

  	pg = (struct ftrace_profile_page *)((unsigned long)rec & PAGE_MASK);

  
   again:

  	if (idx != 0)
  		rec++;

  	if ((void *)rec >= (void *)&pg->records[pg->index]) {
  		pg = pg->next;
  		if (!pg)
  			return NULL;
  		rec = &pg->records[0];

  		if (!rec->counter)
  			goto again;

  	}

  	return rec;
  }
  
  static void *function_stat_start(struct tracer_stat *trace)
  {

  	struct ftrace_profile_stat *stat =
  		container_of(trace, struct ftrace_profile_stat, stat);
  
  	if (!stat || !stat->start)
  		return NULL;
  
  	return function_stat_next(&stat->start->records[0], 0);

  }

  #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  /* function graph compares on total time */
  static int function_stat_cmp(void *p1, void *p2)
  {
  	struct ftrace_profile *a = p1;
  	struct ftrace_profile *b = p2;
  
  	if (a->time < b->time)
  		return -1;
  	if (a->time > b->time)
  		return 1;
  	else
  		return 0;
  }
  #else
  /* not function graph compares against hits */

  static int function_stat_cmp(void *p1, void *p2)
  {

  	struct ftrace_profile *a = p1;
  	struct ftrace_profile *b = p2;

  
  	if (a->counter < b->counter)
  		return -1;
  	if (a->counter > b->counter)
  		return 1;
  	else
  		return 0;
  }

  #endif

  
  static int function_stat_headers(struct seq_file *m)
  {

  #ifdef CONFIG_FUNCTION_GRAPH_TRACER

  	seq_printf(m, "  Function                               "

  		   "Hit    Time            Avg             s^2
  "

  		      "  --------                               "

  		   "---    ----            ---             ---
  ");

  #else

  	seq_printf(m, "  Function                               Hit
  "
  		      "  --------                               ---
  ");

  #endif

  	return 0;
  }
  
  static int function_stat_show(struct seq_file *m, void *v)
  {

  	struct ftrace_profile *rec = v;

  	char str[KSYM_SYMBOL_LEN];

  	int ret = 0;

  #ifdef CONFIG_FUNCTION_GRAPH_TRACER

  	static struct trace_seq s;
  	unsigned long long avg;

  	unsigned long long stddev;

  #endif

  	mutex_lock(&ftrace_profile_lock);
  
  	/* we raced with function_profile_reset() */
  	if (unlikely(rec->counter == 0)) {
  		ret = -EBUSY;
  		goto out;
  	}

  
  	kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);

  	seq_printf(m, "  %-30.30s  %10lu", str, rec->counter);
  
  #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  	seq_printf(m, "    ");

  	avg = rec->time;
  	do_div(avg, rec->counter);

  	/* Sample standard deviation (s^2) */
  	if (rec->counter <= 1)
  		stddev = 0;
  	else {
  		stddev = rec->time_squared - rec->counter * avg * avg;
  		/*
  		 * Divide only 1000 for ns^2 -> us^2 conversion.
  		 * trace_print_graph_duration will divide 1000 again.
  		 */
  		do_div(stddev, (rec->counter - 1) * 1000);
  	}

  	trace_seq_init(&s);
  	trace_print_graph_duration(rec->time, &s);
  	trace_seq_puts(&s, "    ");
  	trace_print_graph_duration(avg, &s);

  	trace_seq_puts(&s, "    ");
  	trace_print_graph_duration(stddev, &s);

  	trace_print_seq(m, &s);

  #endif
  	seq_putc(m, '
  ');

  out:
  	mutex_unlock(&ftrace_profile_lock);

  	return ret;

  }

  static void ftrace_profile_reset(struct ftrace_profile_stat *stat)

  {

  	struct ftrace_profile_page *pg;

  	pg = stat->pages = stat->start;

  	while (pg) {
  		memset(pg->records, 0, PROFILE_RECORDS_SIZE);
  		pg->index = 0;
  		pg = pg->next;

  	}

  	memset(stat->hash, 0,

  	       FTRACE_PROFILE_HASH_SIZE * sizeof(struct hlist_head));
  }

  int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)

  {
  	struct ftrace_profile_page *pg;

  	int functions;
  	int pages;

  	int i;

  	/* If we already allocated, do nothing */

  	if (stat->pages)

  		return 0;

  	stat->pages = (void *)get_zeroed_page(GFP_KERNEL);
  	if (!stat->pages)

  		return -ENOMEM;

  #ifdef CONFIG_DYNAMIC_FTRACE
  	functions = ftrace_update_tot_cnt;
  #else
  	/*
  	 * We do not know the number of functions that exist because
  	 * dynamic tracing is what counts them. With past experience
  	 * we have around 20K functions. That should be more than enough.
  	 * It is highly unlikely we will execute every function in
  	 * the kernel.
  	 */
  	functions = 20000;
  #endif

  	pg = stat->start = stat->pages;

  	pages = DIV_ROUND_UP(functions, PROFILES_PER_PAGE);
  
  	for (i = 0; i < pages; i++) {

  		pg->next = (void *)get_zeroed_page(GFP_KERNEL);

  		if (!pg->next)

  			goto out_free;

  		pg = pg->next;
  	}
  
  	return 0;

  
   out_free:
  	pg = stat->start;
  	while (pg) {
  		unsigned long tmp = (unsigned long)pg;
  
  		pg = pg->next;
  		free_page(tmp);
  	}
  
  	free_page((unsigned long)stat->pages);
  	stat->pages = NULL;
  	stat->start = NULL;
  
  	return -ENOMEM;

  }

  static int ftrace_profile_init_cpu(int cpu)

  {

  	struct ftrace_profile_stat *stat;

  	int size;

  	stat = &per_cpu(ftrace_profile_stats, cpu);
  
  	if (stat->hash) {

  		/* If the profile is already created, simply reset it */

  		ftrace_profile_reset(stat);

  		return 0;
  	}

  	/*
  	 * We are profiling all functions, but usually only a few thousand
  	 * functions are hit. We'll make a hash of 1024 items.
  	 */
  	size = FTRACE_PROFILE_HASH_SIZE;

  	stat->hash = kzalloc(sizeof(struct hlist_head) * size, GFP_KERNEL);

  	if (!stat->hash)

  		return -ENOMEM;

  	if (!ftrace_profile_bits) {
  		size--;

  		for (; size; size >>= 1)
  			ftrace_profile_bits++;
  	}

  	/* Preallocate the function profiling pages */

  	if (ftrace_profile_pages_init(stat) < 0) {
  		kfree(stat->hash);
  		stat->hash = NULL;

  		return -ENOMEM;
  	}
  
  	return 0;

  }

  static int ftrace_profile_init(void)
  {
  	int cpu;
  	int ret = 0;
  
  	for_each_online_cpu(cpu) {
  		ret = ftrace_profile_init_cpu(cpu);
  		if (ret)
  			break;
  	}
  
  	return ret;
  }

  /* interrupts must be disabled */

  static struct ftrace_profile *
  ftrace_find_profiled_func(struct ftrace_profile_stat *stat, unsigned long ip)

  {

  	struct ftrace_profile *rec;

  	struct hlist_head *hhd;
  	struct hlist_node *n;

  	unsigned long key;

  	key = hash_long(ip, ftrace_profile_bits);

  	hhd = &stat->hash[key];

  
  	if (hlist_empty(hhd))
  		return NULL;

  	hlist_for_each_entry_rcu(rec, n, hhd, node) {
  		if (rec->ip == ip)

  			return rec;
  	}
  
  	return NULL;
  }

  static void ftrace_add_profile(struct ftrace_profile_stat *stat,
  			       struct ftrace_profile *rec)

  {
  	unsigned long key;
  
  	key = hash_long(rec->ip, ftrace_profile_bits);

  	hlist_add_head_rcu(&rec->node, &stat->hash[key]);

  }

  /*
   * The memory is already allocated, this simply finds a new record to use.
   */

  static struct ftrace_profile *

  ftrace_profile_alloc(struct ftrace_profile_stat *stat, unsigned long ip)

  {
  	struct ftrace_profile *rec = NULL;

  	/* prevent recursion (from NMIs) */

  	if (atomic_inc_return(&stat->disabled) != 1)

  		goto out;

  	/*

  	 * Try to find the function again since an NMI
  	 * could have added it

  	 */

  	rec = ftrace_find_profiled_func(stat, ip);

  	if (rec)

  		goto out;

  	if (stat->pages->index == PROFILES_PER_PAGE) {
  		if (!stat->pages->next)
  			goto out;
  		stat->pages = stat->pages->next;

  	}

  	rec = &stat->pages->records[stat->pages->index++];

  	rec->ip = ip;

  	ftrace_add_profile(stat, rec);

   out:

  	atomic_dec(&stat->disabled);

  
  	return rec;
  }
  
  static void
  function_profile_call(unsigned long ip, unsigned long parent_ip)
  {

  	struct ftrace_profile_stat *stat;

  	struct ftrace_profile *rec;

  	unsigned long flags;
  
  	if (!ftrace_profile_enabled)
  		return;
  
  	local_irq_save(flags);

  
  	stat = &__get_cpu_var(ftrace_profile_stats);

  	if (!stat->hash || !ftrace_profile_enabled)

  		goto out;
  
  	rec = ftrace_find_profiled_func(stat, ip);

  	if (!rec) {

  		rec = ftrace_profile_alloc(stat, ip);

  		if (!rec)
  			goto out;
  	}

  
  	rec->counter++;
   out:
  	local_irq_restore(flags);
  }

  #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  static int profile_graph_entry(struct ftrace_graph_ent *trace)
  {
  	function_profile_call(trace->func, 0);
  	return 1;
  }
  
  static void profile_graph_return(struct ftrace_graph_ret *trace)
  {

  	struct ftrace_profile_stat *stat;

  	unsigned long long calltime;

  	struct ftrace_profile *rec;

  	unsigned long flags;

  
  	local_irq_save(flags);

  	stat = &__get_cpu_var(ftrace_profile_stats);

  	if (!stat->hash || !ftrace_profile_enabled)

  		goto out;

  	/* If the calltime was zero'd ignore it */
  	if (!trace->calltime)
  		goto out;

  	calltime = trace->rettime - trace->calltime;
  
  	if (!(trace_flags & TRACE_ITER_GRAPH_TIME)) {
  		int index;
  
  		index = trace->depth;
  
  		/* Append this call time to the parent time to subtract */
  		if (index)
  			current->ret_stack[index - 1].subtime += calltime;
  
  		if (current->ret_stack[index].subtime < calltime)
  			calltime -= current->ret_stack[index].subtime;
  		else
  			calltime = 0;
  	}

  	rec = ftrace_find_profiled_func(stat, trace->func);

  	if (rec) {

  		rec->time += calltime;

  		rec->time_squared += calltime * calltime;
  	}

   out:

  	local_irq_restore(flags);
  }
  
  static int register_ftrace_profiler(void)
  {
  	return register_ftrace_graph(&profile_graph_return,
  				     &profile_graph_entry);
  }
  
  static void unregister_ftrace_profiler(void)
  {
  	unregister_ftrace_graph();
  }
  #else

  static struct ftrace_ops ftrace_profile_ops __read_mostly = {

  	.func		= function_profile_call,

  };

  static int register_ftrace_profiler(void)
  {
  	return register_ftrace_function(&ftrace_profile_ops);
  }
  
  static void unregister_ftrace_profiler(void)
  {
  	unregister_ftrace_function(&ftrace_profile_ops);
  }
  #endif /* CONFIG_FUNCTION_GRAPH_TRACER */

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

  	int ret;

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

  		return ret;
  
  	val = !!val;
  
  	mutex_lock(&ftrace_profile_lock);
  	if (ftrace_profile_enabled ^ val) {
  		if (val) {

  			ret = ftrace_profile_init();
  			if (ret < 0) {
  				cnt = ret;
  				goto out;
  			}

  			ret = register_ftrace_profiler();
  			if (ret < 0) {
  				cnt = ret;
  				goto out;
  			}

  			ftrace_profile_enabled = 1;
  		} else {
  			ftrace_profile_enabled = 0;

  			/*
  			 * unregister_ftrace_profiler calls stop_machine
  			 * so this acts like an synchronize_sched.
  			 */

  			unregister_ftrace_profiler();

  		}
  	}

   out:

  	mutex_unlock(&ftrace_profile_lock);

  	*ppos += cnt;

  
  	return cnt;
  }

  static ssize_t
  ftrace_profile_read(struct file *filp, char __user *ubuf,
  		     size_t cnt, loff_t *ppos)
  {

  	char buf[64];		/* big enough to hold a number */

  	int r;
  
  	r = sprintf(buf, "%u
  ", ftrace_profile_enabled);
  	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
  }

  static const struct file_operations ftrace_profile_fops = {
  	.open		= tracing_open_generic,
  	.read		= ftrace_profile_read,
  	.write		= ftrace_profile_write,

  	.llseek		= default_llseek,

  };

  /* used to initialize the real stat files */
  static struct tracer_stat function_stats __initdata = {

  	.name		= "functions",
  	.stat_start	= function_stat_start,
  	.stat_next	= function_stat_next,
  	.stat_cmp	= function_stat_cmp,
  	.stat_headers	= function_stat_headers,
  	.stat_show	= function_stat_show

  };

  static __init void ftrace_profile_debugfs(struct dentry *d_tracer)

  {

  	struct ftrace_profile_stat *stat;

  	struct dentry *entry;

  	char *name;

  	int ret;

  	int cpu;
  
  	for_each_possible_cpu(cpu) {
  		stat = &per_cpu(ftrace_profile_stats, cpu);
  
  		/* allocate enough for function name + cpu number */
  		name = kmalloc(32, GFP_KERNEL);
  		if (!name) {
  			/*
  			 * The files created are permanent, if something happens
  			 * we still do not free memory.
  			 */

  			WARN(1,
  			     "Could not allocate stat file for cpu %d
  ",
  			     cpu);
  			return;
  		}
  		stat->stat = function_stats;
  		snprintf(name, 32, "function%d", cpu);
  		stat->stat.name = name;
  		ret = register_stat_tracer(&stat->stat);
  		if (ret) {
  			WARN(1,
  			     "Could not register function stat for cpu %d
  ",
  			     cpu);
  			kfree(name);
  			return;
  		}

  	}
  
  	entry = debugfs_create_file("function_profile_enabled", 0644,
  				    d_tracer, NULL, &ftrace_profile_fops);
  	if (!entry)
  		pr_warning("Could not create debugfs "
  			   "'function_profile_enabled' entry
  ");
  }

  #else /* CONFIG_FUNCTION_PROFILER */

  static __init void ftrace_profile_debugfs(struct dentry *d_tracer)

  {
  }

  #endif /* CONFIG_FUNCTION_PROFILER */

  static struct pid * const ftrace_swapper_pid = &init_struct_pid;
  
  #ifdef CONFIG_DYNAMIC_FTRACE
  
  #ifndef CONFIG_FTRACE_MCOUNT_RECORD
  # error Dynamic ftrace depends on MCOUNT_RECORD
  #endif
  
  static struct hlist_head ftrace_func_hash[FTRACE_FUNC_HASHSIZE] __read_mostly;
  
  struct ftrace_func_probe {
  	struct hlist_node	node;
  	struct ftrace_probe_ops	*ops;
  	unsigned long		flags;
  	unsigned long		ip;
  	void			*data;
  	struct rcu_head		rcu;
  };

  struct ftrace_func_entry {
  	struct hlist_node hlist;
  	unsigned long ip;
  };
  
  struct ftrace_hash {
  	unsigned long		size_bits;
  	struct hlist_head	*buckets;
  	unsigned long		count;

  	struct rcu_head		rcu;

  };

  /*
   * We make these constant because no one should touch them,
   * but they are used as the default "empty hash", to avoid allocating
   * it all the time. These are in a read only section such that if
   * anyone does try to modify it, it will cause an exception.
   */
  static const struct hlist_head empty_buckets[1];
  static const struct ftrace_hash empty_hash = {
  	.buckets = (struct hlist_head *)empty_buckets,

  };

  #define EMPTY_HASH	((struct ftrace_hash *)&empty_hash)

  static struct ftrace_ops global_ops = {

  	.func			= ftrace_stub,

  	.notrace_hash		= EMPTY_HASH,
  	.filter_hash		= EMPTY_HASH,

  };

  static DEFINE_MUTEX(ftrace_regex_lock);
  
  struct ftrace_page {
  	struct ftrace_page	*next;

  	struct dyn_ftrace	*records;

  	int			index;

  	int			size;

  };

  static struct ftrace_page *ftrace_new_pgs;

  #define ENTRY_SIZE sizeof(struct dyn_ftrace)
  #define ENTRIES_PER_PAGE (PAGE_SIZE / ENTRY_SIZE)

  
  /* estimate from running different kernels */
  #define NR_TO_INIT		10000
  
  static struct ftrace_page	*ftrace_pages_start;
  static struct ftrace_page	*ftrace_pages;

  static bool ftrace_hash_empty(struct ftrace_hash *hash)
  {
  	return !hash || !hash->count;
  }

  static struct ftrace_func_entry *
  ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip)
  {
  	unsigned long key;
  	struct ftrace_func_entry *entry;
  	struct hlist_head *hhd;
  	struct hlist_node *n;

  	if (ftrace_hash_empty(hash))

  		return NULL;
  
  	if (hash->size_bits > 0)
  		key = hash_long(ip, hash->size_bits);
  	else
  		key = 0;
  
  	hhd = &hash->buckets[key];
  
  	hlist_for_each_entry_rcu(entry, n, hhd, hlist) {
  		if (entry->ip == ip)
  			return entry;
  	}
  	return NULL;
  }

  static void __add_hash_entry(struct ftrace_hash *hash,
  			     struct ftrace_func_entry *entry)

  {

  	struct hlist_head *hhd;
  	unsigned long key;

  	if (hash->size_bits)

  		key = hash_long(entry->ip, hash->size_bits);

  	else
  		key = 0;

  	hhd = &hash->buckets[key];
  	hlist_add_head(&entry->hlist, hhd);
  	hash->count++;

  }
  
  static int add_hash_entry(struct ftrace_hash *hash, unsigned long ip)
  {
  	struct ftrace_func_entry *entry;
  
  	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
  	if (!entry)
  		return -ENOMEM;
  
  	entry->ip = ip;
  	__add_hash_entry(hash, entry);

  
  	return 0;
  }
  
  static void

  free_hash_entry(struct ftrace_hash *hash,

  		  struct ftrace_func_entry *entry)
  {
  	hlist_del(&entry->hlist);
  	kfree(entry);
  	hash->count--;
  }

  static void
  remove_hash_entry(struct ftrace_hash *hash,
  		  struct ftrace_func_entry *entry)
  {
  	hlist_del(&entry->hlist);
  	hash->count--;
  }

  static void ftrace_hash_clear(struct ftrace_hash *hash)
  {
  	struct hlist_head *hhd;
  	struct hlist_node *tp, *tn;
  	struct ftrace_func_entry *entry;
  	int size = 1 << hash->size_bits;
  	int i;

  	if (!hash->count)
  		return;

  	for (i = 0; i < size; i++) {
  		hhd = &hash->buckets[i];
  		hlist_for_each_entry_safe(entry, tp, tn, hhd, hlist)

  			free_hash_entry(hash, entry);

  	}
  	FTRACE_WARN_ON(hash->count);
  }

  static void free_ftrace_hash(struct ftrace_hash *hash)
  {
  	if (!hash || hash == EMPTY_HASH)
  		return;
  	ftrace_hash_clear(hash);
  	kfree(hash->buckets);
  	kfree(hash);
  }

  static void __free_ftrace_hash_rcu(struct rcu_head *rcu)
  {
  	struct ftrace_hash *hash;
  
  	hash = container_of(rcu, struct ftrace_hash, rcu);
  	free_ftrace_hash(hash);
  }
  
  static void free_ftrace_hash_rcu(struct ftrace_hash *hash)
  {
  	if (!hash || hash == EMPTY_HASH)
  		return;
  	call_rcu_sched(&hash->rcu, __free_ftrace_hash_rcu);
  }

  static struct ftrace_hash *alloc_ftrace_hash(int size_bits)
  {
  	struct ftrace_hash *hash;
  	int size;
  
  	hash = kzalloc(sizeof(*hash), GFP_KERNEL);
  	if (!hash)
  		return NULL;
  
  	size = 1 << size_bits;
  	hash->buckets = kzalloc(sizeof(*hash->buckets) * size, GFP_KERNEL);
  
  	if (!hash->buckets) {
  		kfree(hash);
  		return NULL;
  	}
  
  	hash->size_bits = size_bits;
  
  	return hash;
  }
  
  static struct ftrace_hash *
  alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash)
  {
  	struct ftrace_func_entry *entry;
  	struct ftrace_hash *new_hash;
  	struct hlist_node *tp;
  	int size;
  	int ret;
  	int i;
  
  	new_hash = alloc_ftrace_hash(size_bits);
  	if (!new_hash)
  		return NULL;
  
  	/* Empty hash? */

  	if (ftrace_hash_empty(hash))

  		return new_hash;
  
  	size = 1 << hash->size_bits;
  	for (i = 0; i < size; i++) {
  		hlist_for_each_entry(entry, tp, &hash->buckets[i], hlist) {
  			ret = add_hash_entry(new_hash, entry->ip);
  			if (ret < 0)
  				goto free_hash;
  		}
  	}
  
  	FTRACE_WARN_ON(new_hash->count != hash->count);
  
  	return new_hash;
  
   free_hash:
  	free_ftrace_hash(new_hash);
  	return NULL;
  }

  static void
  ftrace_hash_rec_disable(struct ftrace_ops *ops, int filter_hash);
  static void
  ftrace_hash_rec_enable(struct ftrace_ops *ops, int filter_hash);

  static int

  ftrace_hash_move(struct ftrace_ops *ops, int enable,
  		 struct ftrace_hash **dst, struct ftrace_hash *src)

  {
  	struct ftrace_func_entry *entry;
  	struct hlist_node *tp, *tn;
  	struct hlist_head *hhd;

  	struct ftrace_hash *old_hash;
  	struct ftrace_hash *new_hash;

  	unsigned long key;
  	int size = src->count;
  	int bits = 0;

  	int ret;

  	int i;
  
  	/*

  	 * Remove the current set, update the hash and add
  	 * them back.
  	 */
  	ftrace_hash_rec_disable(ops, enable);
  
  	/*

  	 * If the new source is empty, just free dst and assign it
  	 * the empty_hash.
  	 */
  	if (!src->count) {

  		free_ftrace_hash_rcu(*dst);
  		rcu_assign_pointer(*dst, EMPTY_HASH);

  		/* still need to update the function records */
  		ret = 0;
  		goto out;

  	}

  	/*
  	 * Make the hash size about 1/2 the # found
  	 */
  	for (size /= 2; size; size >>= 1)
  		bits++;
  
  	/* Don't allocate too much */
  	if (bits > FTRACE_HASH_MAX_BITS)
  		bits = FTRACE_HASH_MAX_BITS;

  	ret = -ENOMEM;

  	new_hash = alloc_ftrace_hash(bits);
  	if (!new_hash)

  		goto out;

  
  	size = 1 << src->size_bits;
  	for (i = 0; i < size; i++) {
  		hhd = &src->buckets[i];
  		hlist_for_each_entry_safe(entry, tp, tn, hhd, hlist) {
  			if (bits > 0)
  				key = hash_long(entry->ip, bits);
  			else
  				key = 0;
  			remove_hash_entry(src, entry);

  			__add_hash_entry(new_hash, entry);

  		}
  	}

  	old_hash = *dst;
  	rcu_assign_pointer(*dst, new_hash);
  	free_ftrace_hash_rcu(old_hash);

  	ret = 0;
   out:
  	/*
  	 * Enable regardless of ret:
  	 *  On success, we enable the new hash.
  	 *  On failure, we re-enable the original hash.
  	 */
  	ftrace_hash_rec_enable(ops, enable);
  
  	return ret;

  }

  /*

   * Test the hashes for this ops to see if we want to call
   * the ops->func or not.
   *
   * It's a match if the ip is in the ops->filter_hash or
   * the filter_hash does not exist or is empty,
   *  AND
   * the ip is not in the ops->notrace_hash.

   *
   * This needs to be called with preemption disabled as
   * the hashes are freed with call_rcu_sched().

   */
  static int
  ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip)
  {
  	struct ftrace_hash *filter_hash;
  	struct ftrace_hash *notrace_hash;
  	int ret;

  	filter_hash = rcu_dereference_raw(ops->filter_hash);
  	notrace_hash = rcu_dereference_raw(ops->notrace_hash);

  	if ((ftrace_hash_empty(filter_hash) ||

  	     ftrace_lookup_ip(filter_hash, ip)) &&

  	    (ftrace_hash_empty(notrace_hash) ||

  	     !ftrace_lookup_ip(notrace_hash, ip)))
  		ret = 1;
  	else
  		ret = 0;

  
  	return ret;
  }
  
  /*

   * This is a double for. Do not use 'break' to break out of the loop,
   * you must use a goto.
   */
  #define do_for_each_ftrace_rec(pg, rec)					\
  	for (pg = ftrace_pages_start; pg; pg = pg->next) {		\
  		int _____i;						\
  		for (_____i = 0; _____i < pg->index; _____i++) {	\
  			rec = &pg->records[_____i];
  
  #define while_for_each_ftrace_rec()		\
  		}				\
  	}

  
  static int ftrace_cmp_recs(const void *a, const void *b)
  {
  	const struct dyn_ftrace *reca = a;
  	const struct dyn_ftrace *recb = b;
  
  	if (reca->ip > recb->ip)
  		return 1;
  	if (reca->ip < recb->ip)
  		return -1;
  	return 0;
  }

  /**
   * ftrace_location - return true if the ip giving is a traced location
   * @ip: the instruction pointer to check
   *
   * Returns 1 if @ip given is a pointer to a ftrace location.
   * That is, the instruction that is either a NOP or call to
   * the function tracer. It checks the ftrace internal tables to
   * determine if the address belongs or not.
   */
  int ftrace_location(unsigned long ip)
  {
  	struct ftrace_page *pg;
  	struct dyn_ftrace *rec;

  	struct dyn_ftrace key;

  	key.ip = ip;
  
  	for (pg = ftrace_pages_start; pg; pg = pg->next) {
  		rec = bsearch(&key, pg->records, pg->index,
  			      sizeof(struct dyn_ftrace),
  			      ftrace_cmp_recs);
  		if (rec)

  			return 1;

  	}

  
  	return 0;
  }

  static void __ftrace_hash_rec_update(struct ftrace_ops *ops,
  				     int filter_hash,
  				     bool inc)
  {
  	struct ftrace_hash *hash;
  	struct ftrace_hash *other_hash;
  	struct ftrace_page *pg;
  	struct dyn_ftrace *rec;
  	int count = 0;
  	int all = 0;
  
  	/* Only update if the ops has been registered */
  	if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
  		return;
  
  	/*
  	 * In the filter_hash case:
  	 *   If the count is zero, we update all records.
  	 *   Otherwise we just update the items in the hash.
  	 *
  	 * In the notrace_hash case:
  	 *   We enable the update in the hash.
  	 *   As disabling notrace means enabling the tracing,
  	 *   and enabling notrace means disabling, the inc variable
  	 *   gets inversed.
  	 */
  	if (filter_hash) {
  		hash = ops->filter_hash;
  		other_hash = ops->notrace_hash;

  		if (ftrace_hash_empty(hash))

  			all = 1;
  	} else {
  		inc = !inc;
  		hash = ops->notrace_hash;
  		other_hash = ops->filter_hash;
  		/*
  		 * If the notrace hash has no items,
  		 * then there's nothing to do.
  		 */

  		if (ftrace_hash_empty(hash))

  			return;
  	}
  
  	do_for_each_ftrace_rec(pg, rec) {
  		int in_other_hash = 0;
  		int in_hash = 0;
  		int match = 0;
  
  		if (all) {
  			/*
  			 * Only the filter_hash affects all records.
  			 * Update if the record is not in the notrace hash.
  			 */

  			if (!other_hash || !ftrace_lookup_ip(other_hash, rec->ip))

  				match = 1;
  		} else {

  			in_hash = !!ftrace_lookup_ip(hash, rec->ip);
  			in_other_hash = !!ftrace_lookup_ip(other_hash, rec->ip);

  
  			/*
  			 *
  			 */
  			if (filter_hash && in_hash && !in_other_hash)
  				match = 1;
  			else if (!filter_hash && in_hash &&

  				 (in_other_hash || ftrace_hash_empty(other_hash)))

  				match = 1;
  		}
  		if (!match)
  			continue;
  
  		if (inc) {
  			rec->flags++;
  			if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == FTRACE_REF_MAX))
  				return;
  		} else {
  			if (FTRACE_WARN_ON((rec->flags & ~FTRACE_FL_MASK) == 0))
  				return;
  			rec->flags--;
  		}
  		count++;
  		/* Shortcut, if we handled all records, we are done. */
  		if (!all && count == hash->count)
  			return;
  	} while_for_each_ftrace_rec();
  }
  
  static void ftrace_hash_rec_disable(struct ftrace_ops *ops,
  				    int filter_hash)
  {
  	__ftrace_hash_rec_update(ops, filter_hash, 0);
  }
  
  static void ftrace_hash_rec_enable(struct ftrace_ops *ops,
  				   int filter_hash)
  {
  	__ftrace_hash_rec_update(ops, filter_hash, 1);
  }

  static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)

  {

  	if (ftrace_pages->index == ftrace_pages->size) {
  		/* We should have allocated enough */
  		if (WARN_ON(!ftrace_pages->next))
  			return NULL;

  		ftrace_pages = ftrace_pages->next;
  	}
  
  	return &ftrace_pages->records[ftrace_pages->index++];
  }

  static struct dyn_ftrace *

  ftrace_record_ip(unsigned long ip)

  {

  	struct dyn_ftrace *rec;

  	if (ftrace_disabled)

  		return NULL;

  	rec = ftrace_alloc_dyn_node(ip);
  	if (!rec)
  		return NULL;

  	rec->ip = ip;

  	return rec;

  }

  static void print_ip_ins(const char *fmt, unsigned char *p)
  {
  	int i;
  
  	printk(KERN_CONT "%s", fmt);
  
  	for (i = 0; i < MCOUNT_INSN_SIZE; i++)
  		printk(KERN_CONT "%s%02x", i ? ":" : "", p[i]);
  }

  /**
   * ftrace_bug - report and shutdown function tracer
   * @failed: The failed type (EFAULT, EINVAL, EPERM)
   * @ip: The address that failed
   *
   * The arch code that enables or disables the function tracing
   * can call ftrace_bug() when it has detected a problem in
   * modifying the code. @failed should be one of either:
   * EFAULT - if the problem happens on reading the @ip address
   * EINVAL - if what is read at @ip is not what was expected
   * EPERM - if the problem happens on writting to the @ip address
   */
  void ftrace_bug(int failed, unsigned long ip)

  {
  	switch (failed) {
  	case -EFAULT:
  		FTRACE_WARN_ON_ONCE(1);
  		pr_info("ftrace faulted on modifying ");
  		print_ip_sym(ip);
  		break;
  	case -EINVAL:
  		FTRACE_WARN_ON_ONCE(1);
  		pr_info("ftrace failed to modify ");
  		print_ip_sym(ip);

  		print_ip_ins(" actual: ", (unsigned char *)ip);

  		printk(KERN_CONT "
  ");
  		break;
  	case -EPERM:
  		FTRACE_WARN_ON_ONCE(1);
  		pr_info("ftrace faulted on writing ");
  		print_ip_sym(ip);
  		break;
  	default:
  		FTRACE_WARN_ON_ONCE(1);
  		pr_info("ftrace faulted on unknown error ");
  		print_ip_sym(ip);
  	}
  }

  /* Return 1 if the address range is reserved for ftrace */
  int ftrace_text_reserved(void *start, void *end)
  {
  	struct dyn_ftrace *rec;
  	struct ftrace_page *pg;
  
  	do_for_each_ftrace_rec(pg, rec) {
  		if (rec->ip <= (unsigned long)end &&
  		    rec->ip + MCOUNT_INSN_SIZE > (unsigned long)start)
  			return 1;
  	} while_for_each_ftrace_rec();
  	return 0;
  }

  static int ftrace_check_record(struct dyn_ftrace *rec, int enable, int update)

  {

  	unsigned long flag = 0UL;

  	/*

  	 * If we are updating calls:

  	 *

  	 *   If the record has a ref count, then we need to enable it
  	 *   because someone is using it.

  	 *

  	 *   Otherwise we make sure its disabled.
  	 *

  	 * If we are disabling calls, then disable all records that

  	 * are enabled.

  	 */

  	if (enable && (rec->flags & ~FTRACE_FL_MASK))

  		flag = FTRACE_FL_ENABLED;

  	/* If the state of this record hasn't changed, then do nothing */
  	if ((rec->flags & FTRACE_FL_ENABLED) == flag)

  		return FTRACE_UPDATE_IGNORE;

  	if (flag) {

  		if (update)
  			rec->flags |= FTRACE_FL_ENABLED;
  		return FTRACE_UPDATE_MAKE_CALL;
  	}
  
  	if (update)
  		rec->flags &= ~FTRACE_FL_ENABLED;
  
  	return FTRACE_UPDATE_MAKE_NOP;
  }
  
  /**
   * ftrace_update_record, set a record that now is tracing or not
   * @rec: the record to update
   * @enable: set to 1 if the record is tracing, zero to force disable
   *
   * The records that represent all functions that can be traced need
   * to be updated when tracing has been enabled.
   */
  int ftrace_update_record(struct dyn_ftrace *rec, int enable)
  {
  	return ftrace_check_record(rec, enable, 1);
  }
  
  /**
   * ftrace_test_record, check if the record has been enabled or not
   * @rec: the record to test
   * @enable: set to 1 to check if enabled, 0 if it is disabled
   *
   * The arch code may need to test if a record is already set to
   * tracing to determine how to modify the function code that it
   * represents.
   */
  int ftrace_test_record(struct dyn_ftrace *rec, int enable)
  {
  	return ftrace_check_record(rec, enable, 0);
  }
  
  static int
  __ftrace_replace_code(struct dyn_ftrace *rec, int enable)
  {
  	unsigned long ftrace_addr;
  	int ret;
  
  	ftrace_addr = (unsigned long)FTRACE_ADDR;
  
  	ret = ftrace_update_record(rec, enable);
  
  	switch (ret) {
  	case FTRACE_UPDATE_IGNORE:
  		return 0;
  
  	case FTRACE_UPDATE_MAKE_CALL:

  		return ftrace_make_call(rec, ftrace_addr);

  
  	case FTRACE_UPDATE_MAKE_NOP:
  		return ftrace_make_nop(NULL, rec, ftrace_addr);

  	}

  	return -1; /* unknow ftrace bug */

  }

  static void ftrace_replace_code(int update)

  {

  	struct dyn_ftrace *rec;
  	struct ftrace_page *pg;

  	int failed;

  	if (unlikely(ftrace_disabled))
  		return;

  	do_for_each_ftrace_rec(pg, rec) {

  		failed = __ftrace_replace_code(rec, update);

  		if (failed) {

  			ftrace_bug(failed, rec->ip);
  			/* Stop processing */
  			return;

  		}

  	} while_for_each_ftrace_rec();

  }

  struct ftrace_rec_iter {
  	struct ftrace_page	*pg;
  	int			index;
  };
  
  /**
   * ftrace_rec_iter_start, start up iterating over traced functions
   *
   * Returns an iterator handle that is used to iterate over all
   * the records that represent address locations where functions
   * are traced.
   *
   * May return NULL if no records are available.
   */
  struct ftrace_rec_iter *ftrace_rec_iter_start(void)
  {
  	/*
  	 * We only use a single iterator.
  	 * Protected by the ftrace_lock mutex.
  	 */
  	static struct ftrace_rec_iter ftrace_rec_iter;
  	struct ftrace_rec_iter *iter = &ftrace_rec_iter;
  
  	iter->pg = ftrace_pages_start;
  	iter->index = 0;
  
  	/* Could have empty pages */
  	while (iter->pg && !iter->pg->index)
  		iter->pg = iter->pg->next;
  
  	if (!iter->pg)
  		return NULL;
  
  	return iter;
  }
  
  /**
   * ftrace_rec_iter_next, get the next record to process.
   * @iter: The handle to the iterator.
   *
   * Returns the next iterator after the given iterator @iter.
   */
  struct ftrace_rec_iter *ftrace_rec_iter_next(struct ftrace_rec_iter *iter)
  {
  	iter->index++;
  
  	if (iter->index >= iter->pg->index) {
  		iter->pg = iter->pg->next;
  		iter->index = 0;
  
  		/* Could have empty pages */
  		while (iter->pg && !iter->pg->index)
  			iter->pg = iter->pg->next;
  	}
  
  	if (!iter->pg)
  		return NULL;
  
  	return iter;
  }
  
  /**
   * ftrace_rec_iter_record, get the record at the iterator location
   * @iter: The current iterator location
   *
   * Returns the record that the current @iter is at.
   */
  struct dyn_ftrace *ftrace_rec_iter_record(struct ftrace_rec_iter *iter)
  {
  	return &iter->pg->records[iter->index];
  }

  static int

  ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec)

  {
  	unsigned long ip;

  	int ret;

  
  	ip = rec->ip;

  	if (unlikely(ftrace_disabled))
  		return 0;

  	ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR);

  	if (ret) {

  		ftrace_bug(ret, ip);

  		return 0;

  	}

  	return 1;

  }

  /*
   * archs can override this function if they must do something
   * before the modifying code is performed.
   */
  int __weak ftrace_arch_code_modify_prepare(void)
  {
  	return 0;
  }
  
  /*
   * archs can override this function if they must do something
   * after the modifying code is performed.
   */
  int __weak ftrace_arch_code_modify_post_process(void)
  {
  	return 0;
  }

  static int __ftrace_modify_code(void *data)

  {

  	int *command = data;

  	if (*command & FTRACE_UPDATE_CALLS)

  		ftrace_replace_code(1);

  	else if (*command & FTRACE_DISABLE_CALLS)

  		ftrace_replace_code(0);
  
  	if (*command & FTRACE_UPDATE_TRACE_FUNC)
  		ftrace_update_ftrace_func(ftrace_trace_function);

  	if (*command & FTRACE_START_FUNC_RET)
  		ftrace_enable_ftrace_graph_caller();
  	else if (*command & FTRACE_STOP_FUNC_RET)
  		ftrace_disable_ftrace_graph_caller();

  	return 0;

  }

  /**
   * ftrace_run_stop_machine, go back to the stop machine method
   * @command: The command to tell ftrace what to do
   *
   * If an arch needs to fall back to the stop machine method, the
   * it can call this function.
   */
  void ftrace_run_stop_machine(int command)
  {
  	stop_machine(__ftrace_modify_code, &command, NULL);
  }
  
  /**
   * arch_ftrace_update_code, modify the code to trace or not trace
   * @command: The command that needs to be done
   *
   * Archs can override this function if it does not need to
   * run stop_machine() to modify code.
   */
  void __weak arch_ftrace_update_code(int command)
  {
  	ftrace_run_stop_machine(command);
  }

  static void ftrace_run_update_code(int command)

  {

  	int ret;
  
  	ret = ftrace_arch_code_modify_prepare();
  	FTRACE_WARN_ON(ret);
  	if (ret)
  		return;

  	/*
  	 * Do not call function tracer while we update the code.
  	 * We are in stop machine.
  	 */
  	function_trace_stop++;

  	/*
  	 * By default we use stop_machine() to modify the code.
  	 * But archs can do what ever they want as long as it
  	 * is safe. The stop_machine() is the safest, but also
  	 * produces the most overhead.
  	 */
  	arch_ftrace_update_code(command);
  
  #ifndef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
  	/*
  	 * For archs that call ftrace_test_stop_func(), we must
  	 * wait till after we update all the function callers
  	 * before we update the callback. This keeps different
  	 * ops that record different functions from corrupting
  	 * each other.
  	 */
  	__ftrace_trace_function = __ftrace_trace_function_delay;
  #endif
  	function_trace_stop--;

  
  	ret = ftrace_arch_code_modify_post_process();
  	FTRACE_WARN_ON(ret);

  }

  static ftrace_func_t saved_ftrace_func;

  static int ftrace_start_up;

  static int global_start_up;

  
  static void ftrace_startup_enable(int command)
  {
  	if (saved_ftrace_func != ftrace_trace_function) {
  		saved_ftrace_func = ftrace_trace_function;
  		command |= FTRACE_UPDATE_TRACE_FUNC;
  	}
  
  	if (!command || !ftrace_enabled)
  		return;
  
  	ftrace_run_update_code(command);
  }

  static int ftrace_startup(struct ftrace_ops *ops, int command)

  {

  	bool hash_enable = true;

  	if (unlikely(ftrace_disabled))

  		return -ENODEV;

  	ftrace_start_up++;

  	command |= FTRACE_UPDATE_CALLS;

  	/* ops marked global share the filter hashes */
  	if (ops->flags & FTRACE_OPS_FL_GLOBAL) {
  		ops = &global_ops;
  		/* Don't update hash if global is already set */
  		if (global_start_up)
  			hash_enable = false;
  		global_start_up++;
  	}

  	ops->flags |= FTRACE_OPS_FL_ENABLED;

  	if (hash_enable)

  		ftrace_hash_rec_enable(ops, 1);

  	ftrace_startup_enable(command);

  
  	return 0;

  }

  static void ftrace_shutdown(struct ftrace_ops *ops, int command)

  {

  	bool hash_disable = true;

  	if (unlikely(ftrace_disabled))
  		return;

  	ftrace_start_up--;

  	/*
  	 * Just warn in case of unbalance, no need to kill ftrace, it's not
  	 * critical but the ftrace_call callers may be never nopped again after
  	 * further ftrace uses.
  	 */
  	WARN_ON_ONCE(ftrace_start_up < 0);

  	if (ops->flags & FTRACE_OPS_FL_GLOBAL) {
  		ops = &global_ops;
  		global_start_up--;
  		WARN_ON_ONCE(global_start_up < 0);
  		/* Don't update hash if global still has users */
  		if (global_start_up) {
  			WARN_ON_ONCE(!ftrace_start_up);
  			hash_disable = false;
  		}
  	}
  
  	if (hash_disable)

  		ftrace_hash_rec_disable(ops, 1);

  	if (ops != &global_ops || !global_start_up)

  		ops->flags &= ~FTRACE_OPS_FL_ENABLED;

  	command |= FTRACE_UPDATE_CALLS;

  	if (saved_ftrace_func != ftrace_trace_function) {
  		saved_ftrace_func = ftrace_trace_function;
  		command |= FTRACE_UPDATE_TRACE_FUNC;
  	}

  	if (!command || !ftrace_enabled)

  		return;

  
  	ftrace_run_update_code(command);

  }

  static void ftrace_startup_sysctl(void)

  {

  	if (unlikely(ftrace_disabled))
  		return;

  	/* Force update next time */
  	saved_ftrace_func = NULL;

  	/* ftrace_start_up is true if we want ftrace running */
  	if (ftrace_start_up)

  		ftrace_run_update_code(FTRACE_UPDATE_CALLS);

  }

  static void ftrace_shutdown_sysctl(void)

  {

  	if (unlikely(ftrace_disabled))
  		return;

  	/* ftrace_start_up is true if ftrace is running */
  	if (ftrace_start_up)

  		ftrace_run_update_code(FTRACE_DISABLE_CALLS);

  }

  static cycle_t		ftrace_update_time;
  static unsigned long	ftrace_update_cnt;
  unsigned long		ftrace_update_tot_cnt;

  static int ops_traces_mod(struct ftrace_ops *ops)
  {
  	struct ftrace_hash *hash;
  
  	hash = ops->filter_hash;

  	return ftrace_hash_empty(hash);

  }

  static int ftrace_update_code(struct module *mod)

  {

  	struct ftrace_page *pg;

  	struct dyn_ftrace *p;

  	cycle_t start, stop;

  	unsigned long ref = 0;

  	int i;

  
  	/*
  	 * When adding a module, we need to check if tracers are
  	 * currently enabled and if they are set to trace all functions.
  	 * If they are, we need to enable the module functions as well
  	 * as update the reference counts for those function records.
  	 */
  	if (mod) {
  		struct ftrace_ops *ops;
  
  		for (ops = ftrace_ops_list;
  		     ops != &ftrace_list_end; ops = ops->next) {
  			if (ops->flags & FTRACE_OPS_FL_ENABLED &&
  			    ops_traces_mod(ops))
  				ref++;
  		}
  	}

  	start = ftrace_now(raw_smp_processor_id());

  	ftrace_update_cnt = 0;

  	for (pg = ftrace_new_pgs; pg; pg = pg->next) {

  		for (i = 0; i < pg->index; i++) {
  			/* If something went wrong, bail without enabling anything */
  			if (unlikely(ftrace_disabled))
  				return -1;

  			p = &pg->records[i];
  			p->flags = ref;

  			/*
  			 * Do the initial record conversion from mcount jump
  			 * to the NOP instructions.
  			 */
  			if (!ftrace_code_disable(mod, p))
  				break;

  			ftrace_update_cnt++;

  			/*
  			 * If the tracing is enabled, go ahead and enable the record.
  			 *
  			 * The reason not to enable the record immediatelly is the
  			 * inherent check of ftrace_make_nop/ftrace_make_call for
  			 * correct previous instructions.  Making first the NOP
  			 * conversion puts the module to the correct state, thus
  			 * passing the ftrace_make_call check.
  			 */
  			if (ftrace_start_up && ref) {
  				int failed = __ftrace_replace_code(p, 1);
  				if (failed)
  					ftrace_bug(failed, p->ip);
  			}

  		}

  	}

  	ftrace_new_pgs = NULL;

  	stop = ftrace_now(raw_smp_processor_id());

  	ftrace_update_time = stop - start;
  	ftrace_update_tot_cnt += ftrace_update_cnt;

  	return 0;
  }