ftrace.c 25.7 KB
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/*
 * 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
 */

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#include <linux/stop_machine.h>
#include <linux/clocksource.h>
#include <linux/kallsyms.h>
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#include <linux/seq_file.h>
#include <linux/debugfs.h>
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#include <linux/kthread.h>
#include <linux/hardirq.h>
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#include <linux/ftrace.h>
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#include <linux/uaccess.h>
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#include <linux/sysctl.h>
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#include <linux/hash.h>
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#include <linux/ctype.h>
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#include <linux/list.h>

#include "trace.h"
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int ftrace_enabled;
static int last_ftrace_enabled;
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static DEFINE_SPINLOCK(ftrace_lock);
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static DEFINE_MUTEX(ftrace_sysctl_lock);

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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;

/* mcount is defined per arch in assembly */
EXPORT_SYMBOL(mcount);

notrace 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;
	};
}

/**
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 * clear_ftrace_function - reset the ftrace function
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 *
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 * This NULLs the ftrace function and in essence stops
 * tracing.  There may be lag
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 */
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void clear_ftrace_function(void)
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{
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	ftrace_trace_function = ftrace_stub;
}

static int notrace __register_ftrace_function(struct ftrace_ops *ops)
{
	/* Should never be called by interrupts */
	spin_lock(&ftrace_lock);
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	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;
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	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;
	}
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	spin_unlock(&ftrace_lock);
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	return 0;
}

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static int notrace __unregister_ftrace_function(struct ftrace_ops *ops)
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{
	struct ftrace_ops **p;
	int ret = 0;

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	spin_lock(&ftrace_lock);
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	/*
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	 * If we are removing the last function, then simply point
	 * to the ftrace_stub.
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	 */
	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;

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	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;
	}
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 out:
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	spin_unlock(&ftrace_lock);

	return ret;
}

#ifdef CONFIG_DYNAMIC_FTRACE

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static struct task_struct *ftraced_task;
static DECLARE_WAIT_QUEUE_HEAD(ftraced_waiters);
static unsigned long ftraced_iteration_counter;

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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),
};

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static int ftrace_filtered;

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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);
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static DEFINE_MUTEX(ftrace_filter_lock);
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struct ftrace_page {
	struct ftrace_page	*next;
	int			index;
	struct dyn_ftrace	records[];
} __attribute__((packed));

#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;

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static int ftraced_trigger;
static int ftraced_suspend;

static int ftrace_record_suspend;

static inline int
notrace 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(p, t, &ftrace_hash[key], node) {
		if (p->ip == ip) {
			found = 1;
			break;
		}
	}

	return found;
}

static inline void notrace
ftrace_add_hash(struct dyn_ftrace *node, unsigned long key)
{
	hlist_add_head(&node->node, &ftrace_hash[key]);
}

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static notrace struct dyn_ftrace *ftrace_alloc_dyn_node(unsigned long ip)
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{
	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++];
}

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static void notrace
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ftrace_record_ip(unsigned long ip)
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{
	struct dyn_ftrace *node;
	unsigned long flags;
	unsigned long key;
	int resched;
	int atomic;

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	if (!ftrace_enabled)
		return;

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	resched = need_resched();
	preempt_disable_notrace();

	/* We simply need to protect against recursion */
	__get_cpu_var(ftrace_shutdown_disable_cpu)++;
	if (__get_cpu_var(ftrace_shutdown_disable_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;

	/*
	 * There's a slight race that the ftraced will update the
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	 * hash and reset here. If it is already converted, skip it.
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	 */
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	if (ftrace_ip_converted(ip))
		goto out_unlock;

	node = ftrace_alloc_dyn_node(ip);
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	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:
	__get_cpu_var(ftrace_shutdown_disable_cpu)--;

	/* prevent recursion with scheduler */
	if (resched)
		preempt_enable_no_resched_notrace();
	else
		preempt_enable_notrace();
}

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#define FTRACE_ADDR ((long)(&ftrace_caller))
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#define MCOUNT_ADDR ((long)(&mcount))

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static void notrace
__ftrace_replace_code(struct dyn_ftrace *rec,
		      unsigned char *old, unsigned char *new, int enable)
{
	unsigned long ip;
	int failed;

	ip = rec->ip;

	if (ftrace_filtered && enable) {
		unsigned long fl;
		/*
		 * 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 not set to be filtered and
		 * it is enabled, disable it.
		 */
		fl = rec->flags & (FTRACE_FL_FILTER | FTRACE_FL_ENABLED);

		if ((fl ==  (FTRACE_FL_FILTER | FTRACE_FL_ENABLED)) ||
		    (fl == 0))
			return;

		/*
		 * 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)
			new = ftrace_call_replace(ip, FTRACE_ADDR);
		else
			old = ftrace_call_replace(ip, FTRACE_ADDR);

		if (enable) {
			if (rec->flags & FTRACE_FL_ENABLED)
				return;
			rec->flags |= FTRACE_FL_ENABLED;
		} else {
			if (!(rec->flags & FTRACE_FL_ENABLED))
				return;
			rec->flags &= ~FTRACE_FL_ENABLED;
		}
	}

	failed = ftrace_modify_code(ip, old, new);
	if (failed)
		rec->flags |= FTRACE_FL_FAILED;
}

static void notrace ftrace_replace_code(int enable)
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{
	unsigned char *new = NULL, *old = NULL;
	struct dyn_ftrace *rec;
	struct ftrace_page *pg;
	int i;

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	if (enable)
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		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;

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			__ftrace_replace_code(rec, old, new, enable);
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		}
	}
}

static notrace void ftrace_shutdown_replenish(void)
{
	if (ftrace_pages->next)
		return;

	/* allocate another page */
	ftrace_pages->next = (void *)get_zeroed_page(GFP_KERNEL);
}
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static notrace void
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ftrace_code_disable(struct dyn_ftrace *rec)
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{
	unsigned long ip;
	unsigned char *nop, *call;
	int failed;

	ip = rec->ip;

	nop = ftrace_nop_replace();
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	call = ftrace_call_replace(ip, MCOUNT_ADDR);
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	failed = ftrace_modify_code(ip, call, nop);
	if (failed)
		rec->flags |= FTRACE_FL_FAILED;
}

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static int notrace __ftrace_modify_code(void *data)
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{
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	unsigned long addr;
	int *command = data;

	if (*command & FTRACE_ENABLE_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_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;
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}

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static void notrace ftrace_run_update_code(int command)
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{
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	stop_machine_run(__ftrace_modify_code, &command, NR_CPUS);
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}

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static ftrace_func_t saved_ftrace_func;

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static void notrace ftrace_startup(void)
{
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	int command = 0;

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	mutex_lock(&ftraced_lock);
	ftraced_suspend++;
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	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)
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		goto out;

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	ftrace_run_update_code(command);
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 out:
	mutex_unlock(&ftraced_lock);
}

static void notrace ftrace_shutdown(void)
{
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	int command = 0;

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	mutex_lock(&ftraced_lock);
	ftraced_suspend--;
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	if (!ftraced_suspend)
		command |= FTRACE_DISABLE_CALLS;
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	if (saved_ftrace_func != ftrace_trace_function) {
		saved_ftrace_func = ftrace_trace_function;
		command |= FTRACE_UPDATE_TRACE_FUNC;
	}
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	if (!command || !ftrace_enabled)
		goto out;

	ftrace_run_update_code(command);
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 out:
	mutex_unlock(&ftraced_lock);
}

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static void notrace ftrace_startup_sysctl(void)
{
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	int command = FTRACE_ENABLE_MCOUNT;

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	mutex_lock(&ftraced_lock);
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	/* Force update next time */
	saved_ftrace_func = NULL;
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	/* ftraced_suspend is true if we want ftrace running */
	if (ftraced_suspend)
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		command |= FTRACE_ENABLE_CALLS;

	ftrace_run_update_code(command);
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	mutex_unlock(&ftraced_lock);
}

static void notrace ftrace_shutdown_sysctl(void)
{
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	int command = FTRACE_DISABLE_MCOUNT;

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	mutex_lock(&ftraced_lock);
	/* ftraced_suspend is true if ftrace is running */
	if (ftraced_suspend)
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		command |= FTRACE_DISABLE_CALLS;

	ftrace_run_update_code(command);
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	mutex_unlock(&ftraced_lock);
}

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

static int notrace __ftrace_update_code(void *ignore)
{
	struct dyn_ftrace *p;
	struct hlist_head head;
	struct hlist_node *t;
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	int save_ftrace_enabled;
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	cycle_t start, stop;
	int i;

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	/* Don't be recording funcs now */
	save_ftrace_enabled = ftrace_enabled;
	ftrace_enabled = 0;
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	start = now(raw_smp_processor_id());
	ftrace_update_cnt = 0;

	/* No locks needed, the machine is stopped! */
	for (i = 0; i < FTRACE_HASHSIZE; i++) {
		if (hlist_empty(&ftrace_hash[i]))
			continue;

		head = ftrace_hash[i];
		INIT_HLIST_HEAD(&ftrace_hash[i]);

		/* all CPUS are stopped, we are safe to modify code */
		hlist_for_each_entry(p, t, &head, node) {
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			ftrace_code_disable(p);
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			ftrace_update_cnt++;
		}

	}

	stop = now(raw_smp_processor_id());
	ftrace_update_time = stop - start;
	ftrace_update_tot_cnt += ftrace_update_cnt;

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	ftrace_enabled = save_ftrace_enabled;
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	return 0;
}

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static void notrace ftrace_update_code(void)
{
	stop_machine_run(__ftrace_update_code, NULL, NR_CPUS);
}

static int notrace ftraced(void *ignore)
{
	unsigned long usecs;

	set_current_state(TASK_INTERRUPTIBLE);

	while (!kthread_should_stop()) {

		/* check once a second */
		schedule_timeout(HZ);

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		mutex_lock(&ftrace_sysctl_lock);
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		mutex_lock(&ftraced_lock);
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		if (ftrace_enabled && ftraced_trigger && !ftraced_suspend) {
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			ftrace_record_suspend++;
			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" : "");
				WARN_ON_ONCE(1);
			}
			ftraced_trigger = 0;
			ftrace_record_suspend--;
		}
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		ftraced_iteration_counter++;
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		mutex_unlock(&ftraced_lock);
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		mutex_unlock(&ftrace_sysctl_lock);
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		wake_up_interruptible(&ftraced_waiters);

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		ftrace_shutdown_replenish();

		set_current_state(TASK_INTERRUPTIBLE);
	}
	__set_current_state(TASK_RUNNING);
	return 0;
}

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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;
}

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enum {
	FTRACE_ITER_FILTER	= (1 << 0),
	FTRACE_ITER_CONT	= (1 << 1),
};

#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 notrace *
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 ((rec->flags & FTRACE_FL_FAILED) ||
		    ((iter->flags & FTRACE_ITER_FILTER) &&
		     !(rec->flags & FTRACE_FL_FILTER))) {
			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 notrace
ftrace_avail_open(struct inode *inode, struct file *file)
{
	struct ftrace_iterator *iter;
	int ret;

	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 void notrace ftrace_filter_reset(void)
{
	struct ftrace_page *pg;
	struct dyn_ftrace *rec;
	unsigned i;

	/* keep kstop machine from running */
	preempt_disable();
	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 &= ~FTRACE_FL_FILTER;
		}
		pg = pg->next;
	}
	preempt_enable();
}

static int notrace
ftrace_filter_open(struct inode *inode, struct file *file)
{
	struct ftrace_iterator *iter;
	int ret = 0;

	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
	if (!iter)
		return -ENOMEM;

	mutex_lock(&ftrace_filter_lock);
	if ((file->f_mode & FMODE_WRITE) &&
	    !(file->f_flags & O_APPEND))
		ftrace_filter_reset();

	if (file->f_mode & FMODE_READ) {
		iter->pg = ftrace_pages_start;
		iter->pos = -1;
		iter->flags = FTRACE_ITER_FILTER;

		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_filter_lock);

	return ret;
}

static ssize_t notrace
ftrace_filter_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 notrace
ftrace_filter_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 notrace
ftrace_match(unsigned char *buff, int len)
{
	char str[KSYM_SYMBOL_LEN];
	char *search = NULL;
	struct ftrace_page *pg;
	struct dyn_ftrace *rec;
	int type = MATCH_FULL;
	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();
	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 |= FTRACE_FL_FILTER;
		}
		pg = pg->next;
	}
	preempt_enable();
}

static ssize_t notrace
ftrace_filter_write(struct file *file, const char __user *ubuf,
		    size_t cnt, loff_t *ppos)
{
	struct ftrace_iterator *iter;
	char ch;
	size_t read = 0;
	ssize_t ret;

	if (!cnt || cnt < 0)
		return 0;

	mutex_lock(&ftrace_filter_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);
		iter->buffer_idx = 0;
	} else
		iter->flags |= FTRACE_ITER_CONT;


	file->f_pos += read;

	ret = read;
 out:
	mutex_unlock(&ftrace_filter_lock);

	return ret;
}

static int notrace
ftrace_filter_release(struct inode *inode, struct file *file)
{
	struct seq_file *m = (struct seq_file *)file->private_data;
	struct ftrace_iterator *iter;

	mutex_lock(&ftrace_filter_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);
	}

	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_filter_lock);
	return 0;
}

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_filter_fops = {
	.open = ftrace_filter_open,
	.read = ftrace_filter_read,
	.write = ftrace_filter_write,
	.llseek = ftrace_filter_lseek,
	.release = ftrace_filter_release,
};

S
Steven Rostedt 已提交
1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102
/**
 * ftrace_force_update - force an update to all recording ftrace functions
 *
 * The ftrace dynamic update daemon only wakes up once a second.
 * There may be cases where an update needs to be done immediately
 * for tests or internal kernel tracing to begin. This function
 * wakes the daemon to do an update and will not return until the
 * update is complete.
 */
int ftrace_force_update(void)
{
	unsigned long last_counter;
	DECLARE_WAITQUEUE(wait, current);
	int ret = 0;

	if (!ftraced_task)
		return -ENODEV;

	mutex_lock(&ftraced_lock);
	last_counter = ftraced_iteration_counter;

	set_current_state(TASK_INTERRUPTIBLE);
	add_wait_queue(&ftraced_waiters, &wait);

	do {
		mutex_unlock(&ftraced_lock);
		wake_up_process(ftraced_task);
		schedule();
		mutex_lock(&ftraced_lock);
		if (signal_pending(current)) {
			ret = -EINTR;
			break;
		}
		set_current_state(TASK_INTERRUPTIBLE);
	} while (last_counter == ftraced_iteration_counter);

	mutex_unlock(&ftraced_lock);
	remove_wait_queue(&ftraced_waiters, &wait);
	set_current_state(TASK_RUNNING);

	return ret;
}

1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125
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("set_ftrace_filter", 0644, d_tracer,
				    NULL, &ftrace_filter_fops);
	if (!entry)
		pr_warning("Could not create debugfs "
			   "'set_ftrace_filter' entry\n");
	return 0;
}

fs_initcall(ftrace_init_debugfs);

1126
static int __init notrace ftrace_dynamic_init(void)
1127 1128
{
	struct task_struct *p;
1129
	unsigned long addr;
1130 1131
	int ret;

1132 1133 1134 1135 1136 1137 1138
	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)
		return addr;

1139
	ret = ftrace_dyn_table_alloc();
1140 1141 1142 1143 1144 1145 1146
	if (ret)
		return ret;

	p = kthread_run(ftraced, NULL, "ftraced");
	if (IS_ERR(p))
		return -1;

1147
	last_ftrace_enabled = ftrace_enabled = 1;
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Steven Rostedt 已提交
1148
	ftraced_task = p;
1149 1150 1151 1152

	return 0;
}

1153
core_initcall(ftrace_dynamic_init);
1154
#else
I
Ingo Molnar 已提交
1155 1156 1157 1158
# 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)
1159 1160
#endif /* CONFIG_DYNAMIC_FTRACE */

1161
/**
1162 1163
 * register_ftrace_function - register a function for profiling
 * @ops - ops structure that holds the function for profiling.
1164
 *
1165 1166 1167 1168 1169 1170
 * 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.
1171
 */
1172
int register_ftrace_function(struct ftrace_ops *ops)
1173
{
1174 1175 1176 1177
	int ret;

	mutex_lock(&ftrace_sysctl_lock);
	ret = __register_ftrace_function(ops);
1178
	ftrace_startup();
1179 1180 1181
	mutex_unlock(&ftrace_sysctl_lock);

	return ret;
1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193
}

/**
 * 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;

1194
	mutex_lock(&ftrace_sysctl_lock);
1195
	ret = __unregister_ftrace_function(ops);
1196
	ftrace_shutdown();
1197 1198 1199 1200 1201 1202 1203
	mutex_unlock(&ftrace_sysctl_lock);

	return ret;
}

notrace int
ftrace_enable_sysctl(struct ctl_table *table, int write,
1204
		     struct file *file, void __user *buffer, size_t *lenp,
1205 1206 1207 1208 1209 1210
		     loff_t *ppos)
{
	int ret;

	mutex_lock(&ftrace_sysctl_lock);

1211
	ret  = proc_dointvec(table, write, file, buffer, lenp, ppos);
1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238

	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);
1239
	return ret;
1240
}