Merge branch 'linus' into timers/nohz

1 files changed, 1727 insertions, 0 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
new file mode 100644
index 00000000000..4231a3dc224
--- /dev/null
+++ b/kernel/trace/ftrace.c
@@ -0,0 +1,1727 @@
+/*
+ * 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/debugfs.h>
+#include <linux/hardirq.h>
+#include <linux/kthread.h>
+#include <linux/uaccess.h>
+#include <linux/kprobes.h>
+#include <linux/ftrace.h>
+#include <linux/sysctl.h>
+#include <linux/ctype.h>
+#include <linux/hash.h>
+#include <linux/list.h>
+
+#include <asm/ftrace.h>
+
+#include "trace.h"
+
+/* ftrace_enabled is a method to turn ftrace on or off */
+int ftrace_enabled __read_mostly;
+static int last_ftrace_enabled;
+
+/*
+ * 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_SPINLOCK(ftrace_lock);
+static DEFINE_MUTEX(ftrace_sysctl_lock);
+
+static struct ftrace_ops ftrace_list_end __read_mostly =
+{
+	.func = ftrace_stub,
+};
+
+static struct ftrace_ops *ftrace_list __read_mostly = &ftrace_list_end;
+ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
+
+static void ftrace_list_func(unsigned long ip, unsigned long parent_ip)
+{
+	struct ftrace_ops *op = ftrace_list;
+
+	/* in case someone actually ports this to alpha! */
+	read_barrier_depends();
+
+	while (op != &ftrace_list_end) {
+		/* silly alpha */
+		read_barrier_depends();
+		op->func(ip, parent_ip);
+		op = op->next;
+	};
+}
+
+/**
+ * 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;
+}
+
+static int __register_ftrace_function(struct ftrace_ops *ops)
+{
+	/* Should never be called by interrupts */
+	spin_lock(&ftrace_lock);
+
+	ops->next = ftrace_list;
+	/*
+	 * We are entering ops into the ftrace_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 ftrace_list.
+	 */
+	smp_wmb();
+	ftrace_list = ops;
+
+	if (ftrace_enabled) {
+		/*
+		 * For one func, simply call it directly.
+		 * For more than one func, call the chain.
+		 */
+		if (ops->next == &ftrace_list_end)
+			ftrace_trace_function = ops->func;
+		else
+			ftrace_trace_function = ftrace_list_func;
+	}
+
+	spin_unlock(&ftrace_lock);
+
+	return 0;
+}
+
+static int __unregister_ftrace_function(struct ftrace_ops *ops)
+{
+	struct ftrace_ops **p;
+	int ret = 0;
+
+	spin_lock(&ftrace_lock);
+
+	/*
+	 * If we are removing the last function, then simply point
+	 * to the ftrace_stub.
+	 */
+	if (ftrace_list == ops && ops->next == &ftrace_list_end) {
+		ftrace_trace_function = ftrace_stub;
+		ftrace_list = &ftrace_list_end;
+		goto out;
+	}
+
+	for (p = &ftrace_list; *p != &ftrace_list_end; p = &(*p)->next)
+		if (*p == ops)
+			break;
+
+	if (*p != ops) {
+		ret = -1;
+		goto out;
+	}
+
+	*p = (*p)->next;
+
+	if (ftrace_enabled) {
+		/* If we only have one func left, then call that directly */
+		if (ftrace_list == &ftrace_list_end ||
+		    ftrace_list->next == &ftrace_list_end)
+			ftrace_trace_function = ftrace_list->func;
+	}
+
+ out:
+	spin_unlock(&ftrace_lock);
+
+	return ret;
+}
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+static struct task_struct *ftraced_task;
+
+enum {
+	FTRACE_ENABLE_CALLS		= (1 << 0),
+	FTRACE_DISABLE_CALLS		= (1 << 1),
+	FTRACE_UPDATE_TRACE_FUNC	= (1 << 2),
+	FTRACE_ENABLE_MCOUNT		= (1 << 3),
+	FTRACE_DISABLE_MCOUNT		= (1 << 4),
+};
+
+static int ftrace_filtered;
+static int tracing_on;
+static int frozen_record_count;
+
+static struct hlist_head ftrace_hash[FTRACE_HASHSIZE];
+
+static DEFINE_PER_CPU(int, ftrace_shutdown_disable_cpu);
+
+static DEFINE_SPINLOCK(ftrace_shutdown_lock);
+static DEFINE_MUTEX(ftraced_lock);
+static DEFINE_MUTEX(ftrace_regex_lock);
+
+struct ftrace_page {
+	struct ftrace_page	*next;
+	unsigned long		index;
+	struct dyn_ftrace	records[];
+};
+
+#define ENTRIES_PER_PAGE \
+  ((PAGE_SIZE - sizeof(struct ftrace_page)) / sizeof(struct dyn_ftrace))
+
+/* estimate from running different kernels */
+#define NR_TO_INIT		10000
+
+static struct ftrace_page	*ftrace_pages_start;
+static struct ftrace_page	*ftrace_pages;
+
+static int ftraced_trigger;
+static int ftraced_suspend;
+static int ftraced_stop;
+
+static int ftrace_record_suspend;
+
+static struct dyn_ftrace *ftrace_free_records;
+
+
+#ifdef CONFIG_KPROBES
+static inline void freeze_record(struct dyn_ftrace *rec)
+{
+	if (!(rec->flags & FTRACE_FL_FROZEN)) {
+		rec->flags |= FTRACE_FL_FROZEN;
+		frozen_record_count++;
+	}
+}
+
+static inline void unfreeze_record(struct dyn_ftrace *rec)
+{
+	if (rec->flags & FTRACE_FL_FROZEN) {
+		rec->flags &= ~FTRACE_FL_FROZEN;
+		frozen_record_count--;
+	}
+}
+
+static inline int record_frozen(struct dyn_ftrace *rec)
+{
+	return rec->flags & FTRACE_FL_FROZEN;
+}
+#else
+# define freeze_record(rec)			({ 0; })
+# define unfreeze_record(rec)			({ 0; })
+# define record_frozen(rec)			({ 0; })
+#endif /* CONFIG_KPROBES */
+
+int skip_trace(unsigned long ip)
+{
+	unsigned long fl;
+	struct dyn_ftrace *rec;
+	struct hlist_node *t;
+	struct hlist_head *head;
+
+	if (frozen_record_count == 0)
+		return 0;
+
+	head = &ftrace_hash[hash_long(ip, FTRACE_HASHBITS)];
+	hlist_for_each_entry_rcu(rec, t, head, node) {
+		if (rec->ip == ip) {
+			if (record_frozen(rec)) {
+				if (rec->flags & FTRACE_FL_FAILED)
+					return 1;
+
+				if (!(rec->flags & FTRACE_FL_CONVERTED))
+					return 1;
+
+				if (!tracing_on || !ftrace_enabled)
+					return 1;
+
+				if (ftrace_filtered) {
+					fl = rec->flags & (FTRACE_FL_FILTER |
+							   FTRACE_FL_NOTRACE);
+					if (!fl || (fl & FTRACE_FL_NOTRACE))
+						return 1;
+				}
+			}
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static inline int
+ftrace_ip_in_hash(unsigned long ip, unsigned long key)
+{
+	struct dyn_ftrace *p;
+	struct hlist_node *t;
+	int found = 0;
+
+	hlist_for_each_entry_rcu(p, t, &ftrace_hash[key], node) {
+		if (p->ip == ip) {
+			found = 1;
+			break;
+		}
+	}
+
+	return found;
+}
+
+static inline void
+ftrace_add_hash(struct dyn_ftrace *node, unsigned long key)
+{
+	hlist_add_head_rcu(&node->node, &ftrace_hash[key]);
+}
+
+/* called from kstop_machine */
+static inline void ftrace_del_hash(struct dyn_ftrace *node)
+{
+	hlist_del(&node->node);
+}
+
+static void ftrace_free_rec(struct dyn_ftrace *rec)
+{
+	/* no locking, only called from kstop_machine */
+
+	rec->ip = (unsigned long)ftrace_free_records;
+	ftrace_free_records = rec;
+	rec->flags |= FTRACE_FL_FREE;
+}
+
+static struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
+{
+	struct dyn_ftrace *rec;
+
+	/* First check for freed records */
+	if (ftrace_free_records) {
+		rec = ftrace_free_records;
+
+		if (unlikely(!(rec->flags & FTRACE_FL_FREE))) {
+			WARN_ON_ONCE(1);
+			ftrace_free_records = NULL;
+			ftrace_disabled = 1;
+			ftrace_enabled = 0;
+			return NULL;
+		}
+
+		ftrace_free_records = (void *)rec->ip;
+		memset(rec, 0, sizeof(*rec));
+		return rec;
+	}
+
+	if (ftrace_pages->index == ENTRIES_PER_PAGE) {
+		if (!ftrace_pages->next)
+			return NULL;
+		ftrace_pages = ftrace_pages->next;
+	}
+
+	return &ftrace_pages->records[ftrace_pages->index++];
+}
+
+static void
+ftrace_record_ip(unsigned long ip)
+{
+	struct dyn_ftrace *node;
+	unsigned long flags;
+	unsigned long key;
+	int resched;
+	int atomic;
+	int cpu;
+
+	if (!ftrace_enabled || ftrace_disabled)
+		return;
+
+	resched = need_resched();
+	preempt_disable_notrace();
+
+	/*
+	 * We simply need to protect against recursion.
+	 * Use the the raw version of smp_processor_id and not
+	 * __get_cpu_var which can call debug hooks that can
+	 * cause a recursive crash here.
+	 */
+	cpu = raw_smp_processor_id();
+	per_cpu(ftrace_shutdown_disable_cpu, cpu)++;
+	if (per_cpu(ftrace_shutdown_disable_cpu, cpu) != 1)
+		goto out;
+
+	if (unlikely(ftrace_record_suspend))
+		goto out;
+
+	key = hash_long(ip, FTRACE_HASHBITS);
+
+	WARN_ON_ONCE(key >= FTRACE_HASHSIZE);
+
+	if (ftrace_ip_in_hash(ip, key))
+		goto out;
+
+	atomic = irqs_disabled();
+
+	spin_lock_irqsave(&ftrace_shutdown_lock, flags);
+
+	/* This ip may have hit the hash before the lock */
+	if (ftrace_ip_in_hash(ip, key))
+		goto out_unlock;
+
+	node = ftrace_alloc_dyn_node(ip);
+	if (!node)
+		goto out_unlock;
+
+	node->ip = ip;
+
+	ftrace_add_hash(node, key);
+
+	ftraced_trigger = 1;
+
+ out_unlock:
+	spin_unlock_irqrestore(&ftrace_shutdown_lock, flags);
+ out:
+	per_cpu(ftrace_shutdown_disable_cpu, cpu)--;
+
+	/* prevent recursion with scheduler */
+	if (resched)
+		preempt_enable_no_resched_notrace();
+	else
+		preempt_enable_notrace();
+}
+
+#define FTRACE_ADDR ((long)(ftrace_caller))
+
+static int
+__ftrace_replace_code(struct dyn_ftrace *rec,
+		      unsigned char *old, unsigned char *new, int enable)
+{
+	unsigned long ip, fl;
+
+	ip = rec->ip;
+
+	if (ftrace_filtered && enable) {
+		/*
+		 * If filtering is on:
+		 *
+		 * If this record is set to be filtered and
+		 * is enabled then do nothing.
+		 *
+		 * If this record is set to be filtered and
+		 * it is not enabled, enable it.
+		 *
+		 * If this record is not set to be filtered
+		 * and it is not enabled do nothing.
+		 *
+		 * If this record is set not to trace then
+		 * do nothing.
+		 *
+		 * If this record is set not to trace and
+		 * it is enabled then disable it.
+		 *
+		 * If this record is not set to be filtered and
+		 * it is enabled, disable it.
+		 */
+
+		fl = rec->flags & (FTRACE_FL_FILTER | FTRACE_FL_NOTRACE |
+				   FTRACE_FL_ENABLED);
+
+		if ((fl ==  (FTRACE_FL_FILTER | FTRACE_FL_ENABLED)) ||
+		    (fl ==  (FTRACE_FL_FILTER | FTRACE_FL_NOTRACE)) ||
+		    !fl || (fl == FTRACE_FL_NOTRACE))
+			return 0;
+
+		/*
+		 * If it is enabled disable it,
+		 * otherwise enable it!
+		 */
+		if (fl & FTRACE_FL_ENABLED) {
+			/* swap new and old */
+			new = old;
+			old = ftrace_call_replace(ip, FTRACE_ADDR);
+			rec->flags &= ~FTRACE_FL_ENABLED;
+		} else {
+			new = ftrace_call_replace(ip, FTRACE_ADDR);
+			rec->flags |= FTRACE_FL_ENABLED;
+		}
+	} else {
+
+		if (enable) {
+			/*
+			 * If this record is set not to trace and is
+			 * not enabled, do nothing.
+			 */
+			fl = rec->flags & (FTRACE_FL_NOTRACE | FTRACE_FL_ENABLED);
+			if (fl == FTRACE_FL_NOTRACE)
+				return 0;
+
+			new = ftrace_call_replace(ip, FTRACE_ADDR);
+		} else
+			old = ftrace_call_replace(ip, FTRACE_ADDR);
+
+		if (enable) {
+			if (rec->flags & FTRACE_FL_ENABLED)
+				return 0;
+			rec->flags |= FTRACE_FL_ENABLED;
+		} else {
+			if (!(rec->flags & FTRACE_FL_ENABLED))
+				return 0;
+			rec->flags &= ~FTRACE_FL_ENABLED;
+		}
+	}
+
+	return ftrace_modify_code(ip, old, new);
+}
+
+static void ftrace_replace_code(int enable)
+{
+	int i, failed;
+	unsigned char *new = NULL, *old = NULL;
+	struct dyn_ftrace *rec;
+	struct ftrace_page *pg;
+
+	if (enable)
+		old = ftrace_nop_replace();
+	else
+		new = ftrace_nop_replace();
+
+	for (pg = ftrace_pages_start; pg; pg = pg->next) {
+		for (i = 0; i < pg->index; i++) {
+			rec = &pg->records[i];
+
+			/* don't modify code that has already faulted */
+			if (rec->flags & FTRACE_FL_FAILED)
+				continue;
+
+			/* ignore updates to this record's mcount site */
+			if (get_kprobe((void *)rec->ip)) {
+				freeze_record(rec);
+				continue;
+			} else {
+				unfreeze_record(rec);
+			}
+
+			failed = __ftrace_replace_code(rec, old, new, enable);
+			if (failed && (rec->flags & FTRACE_FL_CONVERTED)) {
+				rec->flags |= FTRACE_FL_FAILED;
+				if ((system_state == SYSTEM_BOOTING) ||
+				    !core_kernel_text(rec->ip)) {
+					ftrace_del_hash(rec);
+					ftrace_free_rec(rec);
+				}
+			}
+		}
+	}
+}
+
+static void ftrace_shutdown_replenish(void)
+{
+	if (ftrace_pages->next)
+		return;
+
+	/* allocate another page */
+	ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL);
+}
+
+static int
+ftrace_code_disable(struct dyn_ftrace *rec)
+{
+	unsigned long ip;
+	unsigned char *nop, *call;
+	int failed;
+
+	ip = rec->ip;
+
+	nop = ftrace_nop_replace();
+	call = ftrace_call_replace(ip, MCOUNT_ADDR);
+
+	failed = ftrace_modify_code(ip, call, nop);
+	if (failed) {
+		rec->flags |= FTRACE_FL_FAILED;
+		return 0;
+	}
+	return 1;
+}
+
+static int __ftrace_update_code(void *ignore);
+
+static int __ftrace_modify_code(void *data)
+{
+	unsigned long addr;
+	int *command = data;
+
+	if (*command & FTRACE_ENABLE_CALLS) {
+		/*
+		 * Update any recorded ips now that we have the
+		 * machine stopped
+		 */
+		__ftrace_update_code(NULL);
+		ftrace_replace_code(1);
+		tracing_on = 1;
+	} else if (*command & FTRACE_DISABLE_CALLS) {
+		ftrace_replace_code(0);
+		tracing_on = 0;
+	}
+
+	if (*command & FTRACE_UPDATE_TRACE_FUNC)
+		ftrace_update_ftrace_func(ftrace_trace_function);
+
+	if (*command & FTRACE_ENABLE_MCOUNT) {
+		addr = (unsigned long)ftrace_record_ip;
+		ftrace_mcount_set(&addr);
+	} else if (*command & FTRACE_DISABLE_MCOUNT) {
+		addr = (unsigned long)ftrace_stub;
+		ftrace_mcount_set(&addr);
+	}
+
+	return 0;
+}
+
+static void ftrace_run_update_code(int command)
+{
+	stop_machine_run(__ftrace_modify_code, &command, NR_CPUS);
+}
+
+void ftrace_disable_daemon(void)
+{
+	/* Stop the daemon from calling kstop_machine */
+	mutex_lock(&ftraced_lock);
+	ftraced_stop = 1;
+	mutex_unlock(&ftraced_lock);
+
+	ftrace_force_update();
+}
+
+void ftrace_enable_daemon(void)
+{
+	mutex_lock(&ftraced_lock);
+	ftraced_stop = 0;
+	mutex_unlock(&ftraced_lock);
+
+	ftrace_force_update();
+}
+
+static ftrace_func_t saved_ftrace_func;
+
+static void ftrace_startup(void)
+{
+	int command = 0;
+
+	if (unlikely(ftrace_disabled))
+		return;
+
+	mutex_lock(&ftraced_lock);
+	ftraced_suspend++;
+	if (ftraced_suspend == 1)
+		command |= FTRACE_ENABLE_CALLS;
+
+	if (saved_ftrace_func != ftrace_trace_function) {
+		saved_ftrace_func = ftrace_trace_function;
+		command |= FTRACE_UPDATE_TRACE_FUNC;
+	}
+
+	if (!command || !ftrace_enabled)
+		goto out;
+
+	ftrace_run_update_code(command);
+ out:
+	mutex_unlock(&ftraced_lock);
+}
+
+static void ftrace_shutdown(void)
+{
+	int command = 0;
+
+	if (unlikely(ftrace_disabled))
+		return;
+
+	mutex_lock(&ftraced_lock);
+	ftraced_suspend--;
+	if (!ftraced_suspend)
+		command |= FTRACE_DISABLE_CALLS;
+
+	if (saved_ftrace_func != ftrace_trace_function) {
+		saved_ftrace_func = ftrace_trace_function;
+		command |= FTRACE_UPDATE_TRACE_FUNC;
+	}
+
+	if (!command || !ftrace_enabled)
+		goto out;
+
+	ftrace_run_update_code(command);
+ out:
+	mutex_unlock(&ftraced_lock);
+}
+
+static void ftrace_startup_sysctl(void)
+{
+	int command = FTRACE_ENABLE_MCOUNT;
+
+	if (unlikely(ftrace_disabled))
+		return;
+
+	mutex_lock(&ftraced_lock);
+	/* Force update next time */
+	saved_ftrace_func = NULL;
+	/* ftraced_suspend is true if we want ftrace running */
+	if (ftraced_suspend)
+		command |= FTRACE_ENABLE_CALLS;
+
+	ftrace_run_update_code(command);
+	mutex_unlock(&ftraced_lock);
+}
+
+static void ftrace_shutdown_sysctl(void)
+{
+	int command = FTRACE_DISABLE_MCOUNT;
+
+	if (unlikely(ftrace_disabled))
+		return;
+
+	mutex_lock(&ftraced_lock);
+	/* ftraced_suspend is true if ftrace is running */
+	if (ftraced_suspend)
+		command |= FTRACE_DISABLE_CALLS;
+
+	ftrace_run_update_code(command);
+	mutex_unlock(&ftraced_lock);
+}
+
+static cycle_t		ftrace_update_time;
+static unsigned long	ftrace_update_cnt;
+unsigned long		ftrace_update_tot_cnt;
+
+static int __ftrace_update_code(void *ignore)
+{
+	int i, save_ftrace_enabled;
+	cycle_t start, stop;
+	struct dyn_ftrace *p;
+	struct hlist_node *t, *n;
+	struct hlist_head *head, temp_list;
+
+	/* Don't be recording funcs now */
+	ftrace_record_suspend++;
+	save_ftrace_enabled = ftrace_enabled;
+	ftrace_enabled = 0;
+
+	start = ftrace_now(raw_smp_processor_id());
+	ftrace_update_cnt = 0;
+
+	/* No locks needed, the machine is stopped! */
+	for (i = 0; i < FTRACE_HASHSIZE; i++) {
+		INIT_HLIST_HEAD(&temp_list);
+		head = &ftrace_hash[i];
+
+		/* all CPUS are stopped, we are safe to modify code */
+		hlist_for_each_entry_safe(p, t, n, head, node) {
+			/* Skip over failed records which have not been
+			 * freed. */
+			if (p->flags & FTRACE_FL_FAILED)
+				continue;
+
+			/* Unconverted records are always at the head of the
+			 * hash bucket. Once we encounter a converted record,
+			 * simply skip over to the next bucket. Saves ftraced
+			 * some processor cycles (ftrace does its bid for
+			 * global warming :-p ). */
+			if (p->flags & (FTRACE_FL_CONVERTED))
+				break;
+
+			/* Ignore updates to this record's mcount site.
+			 * Reintroduce this record at the head of this
+			 * bucket to attempt to "convert" it again if
+			 * the kprobe on it is unregistered before the
+			 * next run. */
+			if (get_kprobe((void *)p->ip)) {
+				ftrace_del_hash(p);
+				INIT_HLIST_NODE(&p->node);
+				hlist_add_head(&p->node, &temp_list);
+				freeze_record(p);
+				continue;
+			} else {
+				unfreeze_record(p);
+			}
+
+			/* convert record (i.e, patch mcount-call with NOP) */
+			if (ftrace_code_disable(p)) {
+				p->flags |= FTRACE_FL_CONVERTED;
+				ftrace_update_cnt++;
+			} else {
+				if ((system_state == SYSTEM_BOOTING) ||
+				    !core_kernel_text(p->ip)) {
+					ftrace_del_hash(p);
+					ftrace_free_rec(p);
+				}
+			}
+		}
+
+		hlist_for_each_entry_safe(p, t, n, &temp_list, node) {
+			hlist_del(&p->node);
+			INIT_HLIST_NODE(&p->node);
+			hlist_add_head(&p->node, head);
+		}
+	}
+
+	stop = ftrace_now(raw_smp_processor_id());
+	ftrace_update_time = stop - start;
+	ftrace_update_tot_cnt += ftrace_update_cnt;
+	ftraced_trigger = 0;
+
+	ftrace_enabled = save_ftrace_enabled;
+	ftrace_record_suspend--;
+
+	return 0;
+}
+
+static int ftrace_update_code(void)
+{
+	if (unlikely(ftrace_disabled) ||
+	    !ftrace_enabled || !ftraced_trigger)
+		return 0;
+
+	stop_machine_run(__ftrace_update_code, NULL, NR_CPUS);
+
+	return 1;
+}
+
+static int ftraced(void *ignore)
+{
+	unsigned long usecs;
+
+	while (!kthread_should_stop()) {
+
+		set_current_state(TASK_INTERRUPTIBLE);
+
+		/* check once a second */
+		schedule_timeout(HZ);
+
+		if (unlikely(ftrace_disabled))
+			continue;
+
+		mutex_lock(&ftrace_sysctl_lock);
+		mutex_lock(&ftraced_lock);
+		if (!ftraced_suspend && !ftraced_stop &&
+		    ftrace_update_code()) {
+			usecs = nsecs_to_usecs(ftrace_update_time);
+			if (ftrace_update_tot_cnt > 100000) {
+				ftrace_update_tot_cnt = 0;
+				pr_info("hm, dftrace overflow: %lu change%s"
+					" (%lu total) in %lu usec%s\n",
+					ftrace_update_cnt,
+					ftrace_update_cnt != 1 ? "s" : "",
+					ftrace_update_tot_cnt,
+					usecs, usecs != 1 ? "s" : "");
+				ftrace_disabled = 1;
+				WARN_ON_ONCE(1);
+			}
+		}
+		mutex_unlock(&ftraced_lock);
+		mutex_unlock(&ftrace_sysctl_lock);
+
+		ftrace_shutdown_replenish();
+	}
+	__set_current_state(TASK_RUNNING);
+	return 0;
+}
+
+static int __init ftrace_dyn_table_alloc(void)
+{
+	struct ftrace_page *pg;
+	int cnt;
+	int i;
+
+	/* allocate a few pages */
+	ftrace_pages_start = (void *)get_zeroed_page(GFP_KERNEL);
+	if (!ftrace_pages_start)
+		return -1;
+
+	/*
+	 * Allocate a few more pages.
+	 *
+	 * TODO: have some parser search vmlinux before
+	 *   final linking to find all calls to ftrace.
+	 *   Then we can:
+	 *    a) know how many pages to allocate.
+	 *     and/or
+	 *    b) set up the table then.
+	 *
+	 *  The dynamic code is still necessary for
+	 *  modules.
+	 */
+
+	pg = ftrace_pages = ftrace_pages_start;
+
+	cnt = NR_TO_INIT / ENTRIES_PER_PAGE;
+
+	for (i = 0; i < cnt; i++) {
+		pg->next = (void *)get_zeroed_page(GFP_KERNEL);
+
+		/* If we fail, we'll try later anyway */
+		if (!pg->next)
+			break;
+
+		pg = pg->next;
+	}
+
+	return 0;
+}
+
+enum {
+	FTRACE_ITER_FILTER	= (1 << 0),
+	FTRACE_ITER_CONT	= (1 << 1),
+	FTRACE_ITER_NOTRACE	= (1 << 2),
+	FTRACE_ITER_FAILURES	= (1 << 3),
+};
+
+#define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */
+
+struct ftrace_iterator {
+	loff_t			pos;
+	struct ftrace_page	*pg;
+	unsigned		idx;
+	unsigned		flags;
+	unsigned char		buffer[FTRACE_BUFF_MAX+1];
+	unsigned		buffer_idx;
+	unsigned		filtered;
+};
+
+static void *
+t_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct ftrace_iterator *iter = m->private;
+	struct dyn_ftrace *rec = NULL;
+
+	(*pos)++;
+
+ retry:
+	if (iter->idx >= iter->pg->index) {
+		if (iter->pg->next) {
+			iter->pg = iter->pg->next;
+			iter->idx = 0;
+			goto retry;
+		}
+	} else {
+		rec = &iter->pg->records[iter->idx++];
+		if ((!(iter->flags & FTRACE_ITER_FAILURES) &&
+		     (rec->flags & FTRACE_FL_FAILED)) ||
+
+		    ((iter->flags & FTRACE_ITER_FAILURES) &&
+		     (!(rec->flags & FTRACE_FL_FAILED) ||
+		      (rec->flags & FTRACE_FL_FREE))) ||
+
+		    ((iter->flags & FTRACE_ITER_FILTER) &&
+		     !(rec->flags & FTRACE_FL_FILTER)) ||
+
+		    ((iter->flags & FTRACE_ITER_NOTRACE) &&
+		     !(rec->flags & FTRACE_FL_NOTRACE))) {
+			rec = NULL;
+			goto retry;
+		}
+	}
+
+	iter->pos = *pos;
+
+	return rec;
+}
+
+static void *t_start(struct seq_file *m, loff_t *pos)
+{
+	struct ftrace_iterator *iter = m->private;
+	void *p = NULL;
+	loff_t l = -1;
+
+	if (*pos != iter->pos) {
+		for (p = t_next(m, p, &l); p && l < *pos; p = t_next(m, p, &l))
+			;
+	} else {
+		l = *pos;
+		p = t_next(m, p, &l);
+	}
+
+	return p;
+}
+
+static void t_stop(struct seq_file *m, void *p)
+{
+}
+
+static int t_show(struct seq_file *m, void *v)
+{
+	struct dyn_ftrace *rec = v;
+	char str[KSYM_SYMBOL_LEN];
+
+	if (!rec)
+		return 0;
+
+	kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
+
+	seq_printf(m, "%s\n", str);
+
+	return 0;
+}
+
+static struct seq_operations show_ftrace_seq_ops = {
+	.start = t_start,
+	.next = t_next,
+	.stop = t_stop,
+	.show = t_show,
+};
+
+static int
+ftrace_avail_open(struct inode *inode, struct file *file)
+{
+	struct ftrace_iterator *iter;
+	int ret;
+
+	if (unlikely(ftrace_disabled))
+		return -ENODEV;
+
+	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
+	if (!iter)
+		return -ENOMEM;
+
+	iter->pg = ftrace_pages_start;
+	iter->pos = -1;
+
+	ret = seq_open(file, &show_ftrace_seq_ops);
+	if (!ret) {
+		struct seq_file *m = file->private_data;
+
+		m->private = iter;
+	} else {
+		kfree(iter);
+	}
+
+	return ret;
+}
+
+int ftrace_avail_release(struct inode *inode, struct file *file)
+{
+	struct seq_file *m = (struct seq_file *)file->private_data;
+	struct ftrace_iterator *iter = m->private;
+
+	seq_release(inode, file);
+	kfree(iter);
+
+	return 0;
+}
+
+static int
+ftrace_failures_open(struct inode *inode, struct file *file)
+{
+	int ret;
+	struct seq_file *m;
+	struct ftrace_iterator *iter;
+
+	ret = ftrace_avail_open(inode, file);
+	if (!ret) {
+		m = (struct seq_file *)file->private_data;
+		iter = (struct ftrace_iterator *)m->private;
+		iter->flags = FTRACE_ITER_FAILURES;
+	}
+
+	return ret;
+}
+
+
+static void ftrace_filter_reset(int enable)
+{
+	struct ftrace_page *pg;
+	struct dyn_ftrace *rec;
+	unsigned long type = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
+	unsigned i;
+
+	/* keep kstop machine from running */
+	preempt_disable();
+	if (enable)
+		ftrace_filtered = 0;
+	pg = ftrace_pages_start;
+	while (pg) {
+		for (i = 0; i < pg->index; i++) {
+			rec = &pg->records[i];
+			if (rec->flags & FTRACE_FL_FAILED)
+				continue;
+			rec->flags &= ~type;
+		}
+		pg = pg->next;
+	}
+	preempt_enable();
+}
+
+static int
+ftrace_regex_open(struct inode *inode, struct file *file, int enable)
+{
+	struct ftrace_iterator *iter;
+	int ret = 0;
+
+	if (unlikely(ftrace_disabled))
+		return -ENODEV;
+
+	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
+	if (!iter)
+		return -ENOMEM;
+
+	mutex_lock(&ftrace_regex_lock);
+	if ((file->f_mode & FMODE_WRITE) &&
+	    !(file->f_flags & O_APPEND))
+		ftrace_filter_reset(enable);
+
+	if (file->f_mode & FMODE_READ) {
+		iter->pg = ftrace_pages_start;
+		iter->pos = -1;
+		iter->flags = enable ? FTRACE_ITER_FILTER :
+			FTRACE_ITER_NOTRACE;
+
+		ret = seq_open(file, &show_ftrace_seq_ops);
+		if (!ret) {
+			struct seq_file *m = file->private_data;
+			m->private = iter;
+		} else
+			kfree(iter);
+	} else
+		file->private_data = iter;
+	mutex_unlock(&ftrace_regex_lock);
+
+	return ret;
+}
+
+static int
+ftrace_filter_open(struct inode *inode, struct file *file)
+{
+	return ftrace_regex_open(inode, file, 1);
+}
+
+static int
+ftrace_notrace_open(struct inode *inode, struct file *file)
+{
+	return ftrace_regex_open(inode, file, 0);
+}
+
+static ssize_t
+ftrace_regex_read(struct file *file, char __user *ubuf,
+		       size_t cnt, loff_t *ppos)
+{
+	if (file->f_mode & FMODE_READ)
+		return seq_read(file, ubuf, cnt, ppos);
+	else
+		return -EPERM;
+}
+
+static loff_t
+ftrace_regex_lseek(struct file *file, loff_t offset, int origin)
+{
+	loff_t ret;
+
+	if (file->f_mode & FMODE_READ)
+		ret = seq_lseek(file, offset, origin);
+	else
+		file->f_pos = ret = 1;
+
+	return ret;
+}
+
+enum {
+	MATCH_FULL,
+	MATCH_FRONT_ONLY,
+	MATCH_MIDDLE_ONLY,
+	MATCH_END_ONLY,
+};
+
+static void
+ftrace_match(unsigned char *buff, int len, int enable)
+{
+	char str[KSYM_SYMBOL_LEN];
+	char *search = NULL;
+	struct ftrace_page *pg;
+	struct dyn_ftrace *rec;
+	int type = MATCH_FULL;
+	unsigned long flag = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
+	unsigned i, match = 0, search_len = 0;
+
+	for (i = 0; i < len; i++) {
+		if (buff[i] == '*') {
+			if (!i) {
+				search = buff + i + 1;
+				type = MATCH_END_ONLY;
+				search_len = len - (i + 1);
+			} else {
+				if (type == MATCH_END_ONLY) {
+					type = MATCH_MIDDLE_ONLY;
+				} else {
+					match = i;
+					type = MATCH_FRONT_ONLY;
+				}
+				buff[i] = 0;
+				break;
+			}
+		}
+	}
+
+	/* keep kstop machine from running */
+	preempt_disable();
+	if (enable)
+		ftrace_filtered = 1;
+	pg = ftrace_pages_start;
+	while (pg) {
+		for (i = 0; i < pg->index; i++) {
+			int matched = 0;
+			char *ptr;
+
+			rec = &pg->records[i];
+			if (rec->flags & FTRACE_FL_FAILED)
+				continue;
+			kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
+			switch (type) {
+			case MATCH_FULL:
+				if (strcmp(str, buff) == 0)
+					matched = 1;
+				break;
+			case MATCH_FRONT_ONLY:
+				if (memcmp(str, buff, match) == 0)
+					matched = 1;
+				break;
+			case MATCH_MIDDLE_ONLY:
+				if (strstr(str, search))
+					matched = 1;
+				break;
+			case MATCH_END_ONLY:
+				ptr = strstr(str, search);
+				if (ptr && (ptr[search_len] == 0))
+					matched = 1;
+				break;
+			}
+			if (matched)
+				rec->flags |= flag;
+		}
+		pg = pg->next;
+	}
+	preempt_enable();
+}
+
+static ssize_t
+ftrace_regex_write(struct file *file, const char __user *ubuf,
+		   size_t cnt, loff_t *ppos, int enable)
+{
+	struct ftrace_iterator *iter;
+	char ch;
+	size_t read = 0;
+	ssize_t ret;
+
+	if (!cnt || cnt < 0)
+		return 0;
+
+	mutex_lock(&ftrace_regex_lock);
+
+	if (file->f_mode & FMODE_READ) {
+		struct seq_file *m = file->private_data;
+		iter = m->private;
+	} else
+		iter = file->private_data;
+
+	if (!*ppos) {
+		iter->flags &= ~FTRACE_ITER_CONT;
+		iter->buffer_idx = 0;
+	}
+
+	ret = get_user(ch, ubuf++);
+	if (ret)
+		goto out;
+	read++;
+	cnt--;
+
+	if (!(iter->flags & ~FTRACE_ITER_CONT)) {
+		/* skip white space */
+		while (cnt && isspace(ch)) {
+			ret = get_user(ch, ubuf++);
+			if (ret)
+				goto out;
+			read++;
+			cnt--;
+		}
+
+		if (isspace(ch)) {
+			file->f_pos += read;
+			ret = read;
+			goto out;
+		}
+
+		iter->buffer_idx = 0;
+	}
+
+	while (cnt && !isspace(ch)) {
+		if (iter->buffer_idx < FTRACE_BUFF_MAX)
+			iter->buffer[iter->buffer_idx++] = ch;
+		else {
+			ret = -EINVAL;
+			goto out;
+		}
+		ret = get_user(ch, ubuf++);
+		if (ret)
+			goto out;
+		read++;
+		cnt--;
+	}
+
+	if (isspace(ch)) {
+		iter->filtered++;
+		iter->buffer[iter->buffer_idx] = 0;
+		ftrace_match(iter->buffer, iter->buffer_idx, enable);
+		iter->buffer_idx = 0;
+	} else
+		iter->flags |= FTRACE_ITER_CONT;
+
+
+	file->f_pos += read;
+
+	ret = read;
+ out:
+	mutex_unlock(&ftrace_regex_lock);
+
+	return ret;
+}
+
+static ssize_t
+ftrace_filter_write(struct file *file, const char __user *ubuf,
+		    size_t cnt, loff_t *ppos)
+{
+	return ftrace_regex_write(file, ubuf, cnt, ppos, 1);
+}
+
+static ssize_t
+ftrace_notrace_write(struct file *file, const char __user *ubuf,
+		     size_t cnt, loff_t *ppos)
+{
+	return ftrace_regex_write(file, ubuf, cnt, ppos, 0);
+}
+
+static void
+ftrace_set_regex(unsigned char *buf, int len, int reset, int enable)
+{
+	if (unlikely(ftrace_disabled))
+		return;
+
+	mutex_lock(&ftrace_regex_lock);
+	if (reset)
+		ftrace_filter_reset(enable);
+	if (buf)
+		ftrace_match(buf, len, enable);
+	mutex_unlock(&ftrace_regex_lock);
+}
+
+/**
+ * ftrace_set_filter - set a function to filter on in ftrace
+ * @buf - the string that holds the function filter text.
+ * @len - the length of the string.
+ * @reset - non zero to reset all filters before applying this filter.
+ *
+ * Filters denote which functions should be enabled when tracing is enabled.
+ * If @buf is NULL and reset is set, all functions will be enabled for tracing.
+ */
+void ftrace_set_filter(unsigned char *buf, int len, int reset)
+{
+	ftrace_set_regex(buf, len, reset, 1);
+}
+
+/**
+ * ftrace_set_notrace - set a function to not trace in ftrace
+ * @buf - the string that holds the function notrace text.
+ * @len - the length of the string.
+ * @reset - non zero to reset all filters before applying this filter.
+ *
+ * Notrace Filters denote which functions should not be enabled when tracing
+ * is enabled. If @buf is NULL and reset is set, all functions will be enabled
+ * for tracing.
+ */
+void ftrace_set_notrace(unsigned char *buf, int len, int reset)
+{
+	ftrace_set_regex(buf, len, reset, 0);
+}
+
+static int
+ftrace_regex_release(struct inode *inode, struct file *file, int enable)
+{
+	struct seq_file *m = (struct seq_file *)file->private_data;
+	struct ftrace_iterator *iter;
+
+	mutex_lock(&ftrace_regex_lock);
+	if (file->f_mode & FMODE_READ) {
+		iter = m->private;
+
+		seq_release(inode, file);
+	} else
+		iter = file->private_data;
+
+	if (iter->buffer_idx) {
+		iter->filtered++;
+		iter->buffer[iter->buffer_idx] = 0;
+		ftrace_match(iter->buffer, iter->buffer_idx, enable);
+	}
+
+	mutex_lock(&ftrace_sysctl_lock);
+	mutex_lock(&ftraced_lock);
+	if (iter->filtered && ftraced_suspend && ftrace_enabled)
+		ftrace_run_update_code(FTRACE_ENABLE_CALLS);
+	mutex_unlock(&ftraced_lock);
+	mutex_unlock(&ftrace_sysctl_lock);
+
+	kfree(iter);
+	mutex_unlock(&ftrace_regex_lock);
+	return 0;
+}
+
+static int
+ftrace_filter_release(struct inode *inode, struct file *file)
+{
+	return ftrace_regex_release(inode, file, 1);
+}
+
+static int
+ftrace_notrace_release(struct inode *inode, struct file *file)
+{
+	return ftrace_regex_release(inode, file, 0);
+}
+
+static ssize_t
+ftraced_read(struct file *filp, char __user *ubuf,
+		     size_t cnt, loff_t *ppos)
+{
+	/* don't worry about races */
+	char *buf = ftraced_stop ? "disabled\n" : "enabled\n";
+	int r = strlen(buf);
+
+	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
+}
+
+static ssize_t
+ftraced_write(struct file *filp, const char __user *ubuf,
+		      size_t cnt, loff_t *ppos)
+{
+	char buf[64];
+	long val;
+	int ret;
+
+	if (cnt >= sizeof(buf))
+		return -EINVAL;
+
+	if (copy_from_user(&buf, ubuf, cnt))
+		return -EFAULT;
+
+	if (strncmp(buf, "enable", 6) == 0)
+		val = 1;
+	else if (strncmp(buf, "disable", 7) == 0)
+		val = 0;
+	else {
+		buf[cnt] = 0;
+
+		ret = strict_strtoul(buf, 10, &val);
+		if (ret < 0)
+			return ret;
+
+		val = !!val;
+	}
+
+	if (val)
+		ftrace_enable_daemon();
+	else
+		ftrace_disable_daemon();
+
+	filp->f_pos += cnt;
+
+	return cnt;
+}
+
+static struct file_operations ftrace_avail_fops = {
+	.open = ftrace_avail_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = ftrace_avail_release,
+};
+
+static struct file_operations ftrace_failures_fops = {
+	.open = ftrace_failures_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = ftrace_avail_release,
+};
+
+static struct file_operations ftrace_filter_fops = {
+	.open = ftrace_filter_open,
+	.read = ftrace_regex_read,
+	.write = ftrace_filter_write,
+	.llseek = ftrace_regex_lseek,
+	.release = ftrace_filter_release,
+};
+
+static struct file_operations ftrace_notrace_fops = {
+	.open = ftrace_notrace_open,
+	.read = ftrace_regex_read,
+	.write = ftrace_notrace_write,
+	.llseek = ftrace_regex_lseek,
+	.release = ftrace_notrace_release,
+};
+
+static struct file_operations ftraced_fops = {
+	.open = tracing_open_generic,
+	.read = ftraced_read,
+	.write = ftraced_write,
+};
+
+/**
+ * ftrace_force_update - force an update to all recording ftrace functions
+ */
+int ftrace_force_update(void)
+{
+	int ret = 0;
+
+	if (unlikely(ftrace_disabled))
+		return -ENODEV;
+
+	mutex_lock(&ftrace_sysctl_lock);
+	mutex_lock(&ftraced_lock);
+
+	/*
+	 * If ftraced_trigger is not set, then there is nothing
+	 * to update.
+	 */
+	if (ftraced_trigger && !ftrace_update_code())
+		ret = -EBUSY;
+
+	mutex_unlock(&ftraced_lock);
+	mutex_unlock(&ftrace_sysctl_lock);
+
+	return ret;
+}
+
+static void ftrace_force_shutdown(void)
+{
+	struct task_struct *task;
+	int command = FTRACE_DISABLE_CALLS | FTRACE_UPDATE_TRACE_FUNC;
+
+	mutex_lock(&ftraced_lock);
+	task = ftraced_task;
+	ftraced_task = NULL;
+	ftraced_suspend = -1;
+	ftrace_run_update_code(command);
+	mutex_unlock(&ftraced_lock);
+
+	if (task)
+		kthread_stop(task);
+}
+
+static __init int ftrace_init_debugfs(void)
+{
+	struct dentry *d_tracer;
+	struct dentry *entry;
+
+	d_tracer = tracing_init_dentry();
+
+	entry = debugfs_create_file("available_filter_functions", 0444,
+				    d_tracer, NULL, &ftrace_avail_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'available_filter_functions' entry\n");
+
+	entry = debugfs_create_file("failures", 0444,
+				    d_tracer, NULL, &ftrace_failures_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs 'failures' entry\n");
+
+	entry = debugfs_create_file("set_ftrace_filter", 0644, d_tracer,
+				    NULL, &ftrace_filter_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'set_ftrace_filter' entry\n");
+
+	entry = debugfs_create_file("set_ftrace_notrace", 0644, d_tracer,
+				    NULL, &ftrace_notrace_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'set_ftrace_notrace' entry\n");
+
+	entry = debugfs_create_file("ftraced_enabled", 0644, d_tracer,
+				    NULL, &ftraced_fops);
+	if (!entry)
+		pr_warning("Could not create debugfs "
+			   "'ftraced_enabled' entry\n");
+	return 0;
+}
+
+fs_initcall(ftrace_init_debugfs);
+
+static int __init ftrace_dynamic_init(void)
+{
+	struct task_struct *p;
+	unsigned long addr;
+	int ret;
+
+	addr = (unsigned long)ftrace_record_ip;
+
+	stop_machine_run(ftrace_dyn_arch_init, &addr, NR_CPUS);
+
+	/* ftrace_dyn_arch_init places the return code in addr */
+	if (addr) {
+		ret = (int)addr;
+		goto failed;
+	}
+
+	ret = ftrace_dyn_table_alloc();
+	if (ret)
+		goto failed;
+
+	p = kthread_run(ftraced, NULL, "ftraced");
+	if (IS_ERR(p)) {
+		ret = -1;
+		goto failed;
+	}
+
+	last_ftrace_enabled = ftrace_enabled = 1;
+	ftraced_task = p;
+
+	return 0;
+
+ failed:
+	ftrace_disabled = 1;
+	return ret;
+}
+
+core_initcall(ftrace_dynamic_init);
+#else
+# define ftrace_startup()		do { } while (0)
+# define ftrace_shutdown()		do { } while (0)
+# define ftrace_startup_sysctl()	do { } while (0)
+# define ftrace_shutdown_sysctl()	do { } while (0)
+# define ftrace_force_shutdown()	do { } while (0)
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+/**
+ * ftrace_kill_atomic - kill ftrace from critical sections
+ *
+ * This function should be used by panic code. It stops ftrace
+ * but in a not so nice way. If you need to simply kill ftrace
+ * from a non-atomic section, use ftrace_kill.
+ */
+void ftrace_kill_atomic(void)
+{
+	ftrace_disabled = 1;
+	ftrace_enabled = 0;
+#ifdef CONFIG_DYNAMIC_FTRACE
+	ftraced_suspend = -1;
+#endif
+	clear_ftrace_function();
+}
+
+/**
+ * ftrace_kill - totally shutdown ftrace
+ *
+ * This is a safety measure. If something was detected that seems
+ * wrong, calling this function will keep ftrace from doing
+ * any more modifications, and updates.
+ * used when something went wrong.
+ */
+void ftrace_kill(void)
+{
+	mutex_lock(&ftrace_sysctl_lock);
+	ftrace_disabled = 1;
+	ftrace_enabled = 0;
+
+	clear_ftrace_function();
+	mutex_unlock(&ftrace_sysctl_lock);
+
+	/* Try to totally disable ftrace */
+	ftrace_force_shutdown();
+}
+
+/**
+ * register_ftrace_function - register a function for profiling
+ * @ops - ops structure that holds the function for profiling.
+ *
+ * Register a function to be called by all functions in the
+ * kernel.
+ *
+ * Note: @ops->func and all the functions it calls must be labeled
+ *       with "notrace", otherwise it will go into a
+ *       recursive loop.
+ */
+int register_ftrace_function(struct ftrace_ops *ops)
+{
+	int ret;
+
+	if (unlikely(ftrace_disabled))
+		return -1;
+
+	mutex_lock(&ftrace_sysctl_lock);
+	ret = __register_ftrace_function(ops);
+	ftrace_startup();
+	mutex_unlock(&ftrace_sysctl_lock);
+
+	return ret;
+}
+
+/**
+ * unregister_ftrace_function - unresgister a function for profiling.
+ * @ops - ops structure that holds the function to unregister
+ *
+ * Unregister a function that was added to be called by ftrace profiling.
+ */
+int unregister_ftrace_function(struct ftrace_ops *ops)
+{
+	int ret;
+
+	mutex_lock(&ftrace_sysctl_lock);
+	ret = __unregister_ftrace_function(ops);
+	ftrace_shutdown();
+	mutex_unlock(&ftrace_sysctl_lock);
+
+	return ret;
+}
+
+int
+ftrace_enable_sysctl(struct ctl_table *table, int write,
+		     struct file *file, void __user *buffer, size_t *lenp,
+		     loff_t *ppos)
+{
+	int ret;
+
+	if (unlikely(ftrace_disabled))
+		return -ENODEV;
+
+	mutex_lock(&ftrace_sysctl_lock);
+
+	ret  = proc_dointvec(table, write, file, buffer, lenp, ppos);
+
+	if (ret || !write || (last_ftrace_enabled == ftrace_enabled))
+		goto out;
+
+	last_ftrace_enabled = ftrace_enabled;
+
+	if (ftrace_enabled) {
+
+		ftrace_startup_sysctl();
+
+		/* we are starting ftrace again */
+		if (ftrace_list != &ftrace_list_end) {
+			if (ftrace_list->next == &ftrace_list_end)
+				ftrace_trace_function = ftrace_list->func;
+			else
+				ftrace_trace_function = ftrace_list_func;
+		}
+
+	} else {
+		/* stopping ftrace calls (just send to ftrace_stub) */
+		ftrace_trace_function = ftrace_stub;
+
+		ftrace_shutdown_sysctl();
+	}
+
+ out:
+	mutex_unlock(&ftrace_sysctl_lock);
+	return ret;
+}