On Tue, Nov 06, 2007 at 02:33:53AM -0800, akpm@linux-foundation.org wrote:

[mmotm.git] / kernel / trace / ftrace.c

/*
 * 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/kprobes.h>
#include <linux/ftrace.h>
#include <linux/sysctl.h>
#include <linux/ctype.h>
#include <linux/list.h>
#include <linux/hash.h>

#include <trace/events/sched.h>

#include <asm/ftrace.h>
#include <asm/setup.h>

#include "trace_output.h"
#include "trace_stat.h"

#define FTRACE_WARN_ON(cond)                    \
        do {                                    \
                if (WARN_ON(cond))              \
                        ftrace_kill();          \
        } while (0)

#define FTRACE_WARN_ON_ONCE(cond)               \
        do {                                    \
                if (WARN_ON_ONCE(cond))         \
                        ftrace_kill();          \
        } while (0)

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

/* 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;

/*
 * 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_list __read_mostly = &ftrace_list_end;
ftrace_func_t ftrace_trace_function __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 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;
        };
}

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_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 int __register_ftrace_function(struct ftrace_ops *ops)
{
        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) {
                ftrace_func_t func;

                if (ops->next == &ftrace_list_end)
                        func = ops->func;
                else
                        func = ftrace_list_func;

                if (ftrace_pid_trace) {
                        set_ftrace_pid_function(func);
                        func = ftrace_pid_func;
                }

                /*
                 * For one func, simply call it directly.
                 * For more than one func, call the chain.
                 */
#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
                ftrace_trace_function = func;
#else
                __ftrace_trace_function = func;
                ftrace_trace_function = ftrace_test_stop_func;
#endif
        }

        return 0;
}

static int __unregister_ftrace_function(struct ftrace_ops *ops)
{
        struct ftrace_ops **p;

        /*
         * 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;
                return 0;
        }

        for (p = &ftrace_list; *p != &ftrace_list_end; p = &(*p)->next)
                if (*p == ops)
                        break;

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

        *p = (*p)->next;

        if (ftrace_enabled) {
                /* If we only have one func left, then call that directly */
                if (ftrace_list->next == &ftrace_list_end) {
                        ftrace_func_t func = ftrace_list->func;

                        if (ftrace_pid_trace) {
                                set_ftrace_pid_function(func);
                                func = ftrace_pid_func;
                        }
#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
                        ftrace_trace_function = func;
#else
                        __ftrace_trace_function = func;
#endif
                }
        }

        return 0;
}

static void ftrace_update_pid_func(void)
{
        ftrace_func_t func;

        if (ftrace_trace_function == ftrace_stub)
                return;

#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
        func = ftrace_trace_function;
#else
        func = __ftrace_trace_function;
#endif

        if (ftrace_pid_trace) {
                set_ftrace_pid_function(func);
                func = ftrace_pid_func;
        } else {
                if (func == ftrace_pid_func)
                        func = ftrace_pid_function;
        }

#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST
        ftrace_trace_function = func;
#else
        __ftrace_trace_function = func;
#endif
}

#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;
#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\n"
                      "  --------                               "
                   "---    ----            ---\n");
#else
        seq_printf(m, "  Function                               Hit\n"
                      "  --------                               ---\n");
#endif
        return 0;
}

static int function_stat_show(struct seq_file *m, void *v)
{
        struct ftrace_profile *rec = v;
        char str[KSYM_SYMBOL_LEN];
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        static DEFINE_MUTEX(mutex);
        static struct trace_seq s;
        unsigned long long avg;
#endif

        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);

        mutex_lock(&mutex);
        trace_seq_init(&s);
        trace_print_graph_duration(rec->time, &s);
        trace_seq_puts(&s, "    ");
        trace_print_graph_duration(avg, &s);
        trace_print_seq(m, &s);
        mutex_unlock(&mutex);
#endif
        seq_putc(m, '\n');

        return 0;
}

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;

        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;

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

        if (cnt >= sizeof(buf))
                return -EINVAL;

        if (copy_from_user(&buf, ubuf, cnt))
                return -EFAULT;

        buf[cnt] = 0;

        ret = strict_strtoul(buf, 10, &val);
        if (ret < 0)
                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);

        filp->f_pos += 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\n", 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,
};

/* 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\n",
                             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\n",
                             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\n");
}

#else /* CONFIG_FUNCTION_PROFILER */
static __init void ftrace_profile_debugfs(struct dentry *d_tracer)
{
}
#endif /* CONFIG_FUNCTION_PROFILER */

/* set when tracing only a pid */
struct pid *ftrace_pid_trace;
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;
};

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),
        FTRACE_START_FUNC_RET           = (1 << 5),
        FTRACE_STOP_FUNC_RET            = (1 << 6),
};

static int ftrace_filtered;

static struct dyn_ftrace *ftrace_new_addrs;

static DEFINE_MUTEX(ftrace_regex_lock);

struct ftrace_page {
        struct ftrace_page      *next;
        int                     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 struct dyn_ftrace *ftrace_free_records;

/*
 * 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()             \
                }                               \
        }

#ifdef CONFIG_KPROBES

static int frozen_record_count;

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 */

static void ftrace_free_rec(struct dyn_ftrace *rec)
{
        rec->freelist = 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))) {
                        FTRACE_WARN_ON_ONCE(1);
                        ftrace_free_records = NULL;
                        return NULL;
                }

                ftrace_free_records = rec->freelist;
                memset(rec, 0, sizeof(*rec));
                return rec;
        }

        if (ftrace_pages->index == ENTRIES_PER_PAGE) {
                if (!ftrace_pages->next) {
                        /* allocate another page */
                        ftrace_pages->next =
                                (void *)get_zeroed_page(GFP_KERNEL);
                        if (!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;
        rec->newlist = ftrace_new_addrs;
        ftrace_new_addrs = rec;

        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]);
}

static 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 "\n");
                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);
        }
}


static int
__ftrace_replace_code(struct dyn_ftrace *rec, int enable)
{
        unsigned long ftrace_addr;
        unsigned long flag = 0UL;

        ftrace_addr = (unsigned long)FTRACE_ADDR;

        /*
         * If this record is not to be traced or we want to disable it,
         * then disable it.
         *
         * If we want to enable it and filtering is off, then enable it.
         *
         * If we want to enable it and filtering is on, enable it only if
         * it's filtered
         */
        if (enable && !(rec->flags & FTRACE_FL_NOTRACE)) {
                if (!ftrace_filtered || (rec->flags & FTRACE_FL_FILTER))
                        flag = FTRACE_FL_ENABLED;
        }

        /* If the state of this record hasn't changed, then do nothing */
        if ((rec->flags & FTRACE_FL_ENABLED) == flag)
                return 0;

        if (flag) {
                rec->flags |= FTRACE_FL_ENABLED;
                return ftrace_make_call(rec, ftrace_addr);
        }

        rec->flags &= ~FTRACE_FL_ENABLED;
        return ftrace_make_nop(NULL, rec, ftrace_addr);
}

static void ftrace_replace_code(int enable)
{
        struct dyn_ftrace *rec;
        struct ftrace_page *pg;
        int failed;

        do_for_each_ftrace_rec(pg, rec) {
                /*
                 * Skip over free records, records that have
                 * failed and not converted.
                 */
                if (rec->flags & FTRACE_FL_FREE ||
                    rec->flags & FTRACE_FL_FAILED ||
                    !(rec->flags & FTRACE_FL_CONVERTED))
                        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, enable);
                if (failed) {
                        rec->flags |= FTRACE_FL_FAILED;
                        ftrace_bug(failed, rec->ip);
                        /* Stop processing */
                        return;
                }
        } while_for_each_ftrace_rec();
}

static int
ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec)
{
        unsigned long ip;
        int ret;

        ip = rec->ip;

        ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
        if (ret) {
                ftrace_bug(ret, ip);
                rec->flags |= FTRACE_FL_FAILED;
                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_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_START_FUNC_RET)
                ftrace_enable_ftrace_graph_caller();
        else if (*command & FTRACE_STOP_FUNC_RET)
                ftrace_disable_ftrace_graph_caller();

        return 0;
}

static void ftrace_run_update_code(int command)
{
        int ret;

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

        stop_machine(__ftrace_modify_code, &command, NULL);

        ret = ftrace_arch_code_modify_post_process();
        FTRACE_WARN_ON(ret);
}

static ftrace_func_t saved_ftrace_func;
static int ftrace_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 void ftrace_startup(int command)
{
        if (unlikely(ftrace_disabled))
                return;

        ftrace_start_up++;
        command |= FTRACE_ENABLE_CALLS;

        ftrace_startup_enable(command);
}

static void ftrace_shutdown(int command)
{
        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 (!ftrace_start_up)
                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)
                return;

        ftrace_run_update_code(command);
}

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

        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)
                command |= FTRACE_ENABLE_CALLS;

        ftrace_run_update_code(command);
}

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

        if (unlikely(ftrace_disabled))
                return;

        /* ftrace_start_up is true if ftrace is running */
        if (ftrace_start_up)
                command |= FTRACE_DISABLE_CALLS;

        ftrace_run_update_code(command);
}

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

static int ftrace_update_code(struct module *mod)
{
        struct dyn_ftrace *p;
        cycle_t start, stop;

        start = ftrace_now(raw_smp_processor_id());
        ftrace_update_cnt = 0;

        while (ftrace_new_addrs) {

                /* If something went wrong, bail without enabling anything */
                if (unlikely(ftrace_disabled))
                        return -1;

                p = ftrace_new_addrs;
                ftrace_new_addrs = p->newlist;
                p->flags = 0L;

                /* convert record (i.e, patch mcount-call with NOP) */
                if (ftrace_code_disable(mod, p)) {
                        p->flags |= FTRACE_FL_CONVERTED;
                        ftrace_update_cnt++;
                } else
                        ftrace_free_rec(p);
        }

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

        return 0;
}

static int __init ftrace_dyn_table_alloc(unsigned long num_to_init)
{
        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 = num_to_init / ENTRIES_PER_PAGE;
        pr_info("ftrace: allocating %ld entries in %d pages\n",
                num_to_init, cnt + 1);

        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_NOTRACE     = (1 << 1),
        FTRACE_ITER_FAILURES    = (1 << 2),
        FTRACE_ITER_PRINTALL    = (1 << 3),
        FTRACE_ITER_HASH        = (1 << 4),
};

#define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */

struct ftrace_iterator {
        struct ftrace_page      *pg;
        int                     hidx;
        int                     idx;
        unsigned                flags;
        struct trace_parser     parser;
};

static void *
t_hash_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct ftrace_iterator *iter = m->private;
        struct hlist_node *hnd = v;
        struct hlist_head *hhd;

        WARN_ON(!(iter->flags & FTRACE_ITER_HASH));

        (*pos)++;

 retry:
        if (iter->hidx >= FTRACE_FUNC_HASHSIZE)
                return NULL;

        hhd = &ftrace_func_hash[iter->hidx];

        if (hlist_empty(hhd)) {
                iter->hidx++;
                hnd = NULL;
                goto retry;
        }

        if (!hnd)
                hnd = hhd->first;
        else {
                hnd = hnd->next;
                if (!hnd) {
                        iter->hidx++;
                        goto retry;
                }
        }

        return hnd;
}

static void *t_hash_start(struct seq_file *m, loff_t *pos)
{
        struct ftrace_iterator *iter = m->private;
        void *p = NULL;
        loff_t l;

        if (!(iter->flags & FTRACE_ITER_HASH))
                *pos = 0;

        iter->flags |= FTRACE_ITER_HASH;

        iter->hidx = 0;
        for (l = 0; l <= *pos; ) {
                p = t_hash_next(m, p, &l);
                if (!p)
                        break;
        }
        return p;
}

static int t_hash_show(struct seq_file *m, void *v)
{
        struct ftrace_func_probe *rec;
        struct hlist_node *hnd = v;

        rec = hlist_entry(hnd, struct ftrace_func_probe, node);

        if (rec->ops->print)
                return rec->ops->print(m, rec->ip, rec->ops, rec->data);

        seq_printf(m, "%ps:%ps", (void *)rec->ip, (void *)rec->ops->func);

        if (rec->data)
                seq_printf(m, ":%p", rec->data);
        seq_putc(m, '\n');

        return 0;
}

static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct ftrace_iterator *iter = m->private;
        struct dyn_ftrace *rec = NULL;

        if (iter->flags & FTRACE_ITER_HASH)
                return t_hash_next(m, v, pos);

        (*pos)++;

        if (iter->flags & FTRACE_ITER_PRINTALL)
                return NULL;

 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_FREE) ||

                    (!(iter->flags & FTRACE_ITER_FAILURES) &&
                     (rec->flags & FTRACE_FL_FAILED)) ||

                    ((iter->flags & FTRACE_ITER_FAILURES) &&
                     !(rec->flags & FTRACE_FL_FAILED)) ||

                    ((iter->flags & FTRACE_ITER_FILTER) &&
                     !(rec->flags & FTRACE_FL_FILTER)) ||

                    ((iter->flags & FTRACE_ITER_NOTRACE) &&
                     !(rec->flags & FTRACE_FL_NOTRACE))) {
                        rec = NULL;
                        goto retry;
                }
        }

        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;

        mutex_lock(&ftrace_lock);
        /*
         * For set_ftrace_filter reading, if we have the filter
         * off, we can short cut and just print out that all
         * functions are enabled.
         */
        if (iter->flags & FTRACE_ITER_FILTER && !ftrace_filtered) {
                if (*pos > 0)
                        return t_hash_start(m, pos);
                iter->flags |= FTRACE_ITER_PRINTALL;
                return iter;
        }

        if (iter->flags & FTRACE_ITER_HASH)
                return t_hash_start(m, pos);

        iter->pg = ftrace_pages_start;
        iter->idx = 0;
        for (l = 0; l <= *pos; ) {
                p = t_next(m, p, &l);
                if (!p)
                        break;
        }

        if (!p && iter->flags & FTRACE_ITER_FILTER)
                return t_hash_start(m, pos);

        return p;
}

static void t_stop(struct seq_file *m, void *p)
{
        mutex_unlock(&ftrace_lock);
}

static int t_show(struct seq_file *m, void *v)
{
        struct ftrace_iterator *iter = m->private;
        struct dyn_ftrace *rec = v;

        if (iter->flags & FTRACE_ITER_HASH)
                return t_hash_show(m, v);

        if (iter->flags & FTRACE_ITER_PRINTALL) {
                seq_printf(m, "#### all functions enabled ####\n");
                return 0;
        }

        if (!rec)
                return 0;

        seq_printf(m, "%ps\n", (void *)rec->ip);

        return 0;
}

static const 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;

        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;
}

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;

        mutex_lock(&ftrace_lock);
        if (enable)
                ftrace_filtered = 0;
        do_for_each_ftrace_rec(pg, rec) {
                if (rec->flags & FTRACE_FL_FAILED)
                        continue;
                rec->flags &= ~type;
        } while_for_each_ftrace_rec();
        mutex_unlock(&ftrace_lock);
}

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;

        if (trace_parser_get_init(&iter->parser, FTRACE_BUFF_MAX)) {
                kfree(iter);
                return -ENOMEM;
        }

        mutex_lock(&ftrace_regex_lock);
        if ((file->f_mode & FMODE_WRITE) &&
            (file->f_flags & O_TRUNC))
                ftrace_filter_reset(enable);

        if (file->f_mode & FMODE_READ) {
                iter->pg = ftrace_pages_start;
                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 {
                        trace_parser_put(&iter->parser);
                        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 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;
}

static int ftrace_match(char *str, char *regex, int len, int type)
{
        int matched = 0;
        char *ptr;

        switch (type) {
        case MATCH_FULL:
                if (strcmp(str, regex) == 0)
                        matched = 1;
                break;
        case MATCH_FRONT_ONLY:
                if (strncmp(str, regex, len) == 0)
                        matched = 1;
                break;
        case MATCH_MIDDLE_ONLY:
                if (strstr(str, regex))
                        matched = 1;
                break;
        case MATCH_END_ONLY:
                ptr = strstr(str, regex);
                if (ptr && (ptr[len] == 0))
                        matched = 1;
                break;
        }

        return matched;
}

static int
ftrace_match_record(struct dyn_ftrace *rec, char *regex, int len, int type)
{
        char str[KSYM_SYMBOL_LEN];

        kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
        return ftrace_match(str, regex, len, type);
}

static void ftrace_match_records(char *buff, int len, int enable)
{
        unsigned int search_len;
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;
        unsigned long flag;
        char *search;
        int type;
        int not;

        flag = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;
        type = filter_parse_regex(buff, len, &search, &not);

        search_len = strlen(search);

        mutex_lock(&ftrace_lock);
        do_for_each_ftrace_rec(pg, rec) {

                if (rec->flags & FTRACE_FL_FAILED)
                        continue;

                if (ftrace_match_record(rec, search, search_len, type)) {
                        if (not)
                                rec->flags &= ~flag;
                        else
                                rec->flags |= flag;
                }
                /*
                 * Only enable filtering if we have a function that
                 * is filtered on.
                 */
                if (enable && (rec->flags & FTRACE_FL_FILTER))
                        ftrace_filtered = 1;
        } while_for_each_ftrace_rec();
        mutex_unlock(&ftrace_lock);
}

static int
ftrace_match_module_record(struct dyn_ftrace *rec, char *mod,
                           char *regex, int len, int type)
{
        char str[KSYM_SYMBOL_LEN];
        char *modname;

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

        if (!modname || strcmp(modname, mod))
                return 0;

        /* blank search means to match all funcs in the mod */
        if (len)
                return ftrace_match(str, regex, len, type);
        else
                return 1;
}

static void ftrace_match_module_records(char *buff, char *mod, int enable)
{
        unsigned search_len = 0;
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;
        int type = MATCH_FULL;
        char *search = buff;
        unsigned long flag;
        int not = 0;

        flag = enable ? FTRACE_FL_FILTER : FTRACE_FL_NOTRACE;

        /* blank or '*' mean the same */
        if (strcmp(buff, "*") == 0)
                buff[0] = 0;

        /* handle the case of 'dont filter this module' */
        if (strcmp(buff, "!") == 0 || strcmp(buff, "!*") == 0) {
                buff[0] = 0;
                not = 1;
        }

        if (strlen(buff)) {
                type = filter_parse_regex(buff, strlen(buff), &search, &not);
                search_len = strlen(search);
        }

        mutex_lock(&ftrace_lock);
        do_for_each_ftrace_rec(pg, rec) {

                if (rec->flags & FTRACE_FL_FAILED)
                        continue;

                if (ftrace_match_module_record(rec, mod,
                                               search, search_len, type)) {
                        if (not)
                                rec->flags &= ~flag;
                        else
                                rec->flags |= flag;
                }
                if (enable && (rec->flags & FTRACE_FL_FILTER))
                        ftrace_filtered = 1;

        } while_for_each_ftrace_rec();
        mutex_unlock(&ftrace_lock);
}

/*
 * We register the module command as a template to show others how
 * to register the a command as well.
 */

static int
ftrace_mod_callback(char *func, char *cmd, char *param, int enable)
{
        char *mod;

        /*
         * cmd == 'mod' because we only registered this func
         * for the 'mod' ftrace_func_command.
         * But if you register one func with multiple commands,
         * you can tell which command was used by the cmd
         * parameter.
         */

        /* we must have a module name */
        if (!param)
                return -EINVAL;

        mod = strsep(&param, ":");
        if (!strlen(mod))
                return -EINVAL;

        ftrace_match_module_records(func, mod, enable);
        return 0;
}

static struct ftrace_func_command ftrace_mod_cmd = {
        .name                   = "mod",
        .func                   = ftrace_mod_callback,
};

static int __init ftrace_mod_cmd_init(void)
{
        return register_ftrace_command(&ftrace_mod_cmd);
}
device_initcall(ftrace_mod_cmd_init);

static void
function_trace_probe_call(unsigned long ip, unsigned long parent_ip)
{
        struct ftrace_func_probe *entry;
        struct hlist_head *hhd;
        struct hlist_node *n;
        unsigned long key;
        int resched;

        key = hash_long(ip, FTRACE_HASH_BITS);

        hhd = &ftrace_func_hash[key];

        if (hlist_empty(hhd))
                return;

        /*
         * Disable preemption for these calls to prevent a RCU grace
         * period. This syncs the hash iteration and freeing of items
         * on the hash. rcu_read_lock is too dangerous here.
         */
        resched = ftrace_preempt_disable();
        hlist_for_each_entry_rcu(entry, n, hhd, node) {
                if (entry->ip == ip)
                        entry->ops->func(ip, parent_ip, &entry->data);
        }
        ftrace_preempt_enable(resched);
}

static struct ftrace_ops trace_probe_ops __read_mostly =
{
        .func           = function_trace_probe_call,
};

static int ftrace_probe_registered;

static void __enable_ftrace_function_probe(void)
{
        int i;

        if (ftrace_probe_registered)
                return;

        for (i = 0; i < FTRACE_FUNC_HASHSIZE; i++) {
                struct hlist_head *hhd = &ftrace_func_hash[i];
                if (hhd->first)
                        break;
        }
        /* Nothing registered? */
        if (i == FTRACE_FUNC_HASHSIZE)
                return;

        __register_ftrace_function(&trace_probe_ops);
        ftrace_startup(0);
        ftrace_probe_registered = 1;
}

static void __disable_ftrace_function_probe(void)
{
        int i;

        if (!ftrace_probe_registered)
                return;

        for (i = 0; i < FTRACE_FUNC_HASHSIZE; i++) {
                struct hlist_head *hhd = &ftrace_func_hash[i];
                if (hhd->first)
                        return;
        }

        /* no more funcs left */
        __unregister_ftrace_function(&trace_probe_ops);
        ftrace_shutdown(0);
        ftrace_probe_registered = 0;
}


static void ftrace_free_entry_rcu(struct rcu_head *rhp)
{
        struct ftrace_func_probe *entry =
                container_of(rhp, struct ftrace_func_probe, rcu);

        if (entry->ops->free)
                entry->ops->free(&entry->data);
        kfree(entry);
}


int
register_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
                              void *data)
{
        struct ftrace_func_probe *entry;
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;
        int type, len, not;
        unsigned long key;
        int count = 0;
        char *search;

        type = filter_parse_regex(glob, strlen(glob), &search, &not);
        len = strlen(search);

        /* we do not support '!' for function probes */
        if (WARN_ON(not))
                return -EINVAL;

        mutex_lock(&ftrace_lock);
        do_for_each_ftrace_rec(pg, rec) {

                if (rec->flags & FTRACE_FL_FAILED)
                        continue;

                if (!ftrace_match_record(rec, search, len, type))
                        continue;

                entry = kmalloc(sizeof(*entry), GFP_KERNEL);
                if (!entry) {
                        /* If we did not process any, then return error */
                        if (!count)
                                count = -ENOMEM;
                        goto out_unlock;
                }

                count++;

                entry->data = data;

                /*
                 * The caller might want to do something special
                 * for each function we find. We call the callback
                 * to give the caller an opportunity to do so.
                 */
                if (ops->callback) {
                        if (ops->callback(rec->ip, &entry->data) < 0) {
                                /* caller does not like this func */
                                kfree(entry);
                                continue;
                        }
                }

                entry->ops = ops;
                entry->ip = rec->ip;

                key = hash_long(entry->ip, FTRACE_HASH_BITS);
                hlist_add_head_rcu(&entry->node, &ftrace_func_hash[key]);

        } while_for_each_ftrace_rec();
        __enable_ftrace_function_probe();

 out_unlock:
        mutex_unlock(&ftrace_lock);

        return count;
}

enum {
        PROBE_TEST_FUNC         = 1,
        PROBE_TEST_DATA         = 2
};

static void
__unregister_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
                                  void *data, int flags)
{
        struct ftrace_func_probe *entry;
        struct hlist_node *n, *tmp;
        char str[KSYM_SYMBOL_LEN];
        int type = MATCH_FULL;
        int i, len = 0;
        char *search;

        if (glob && (strcmp(glob, "*") == 0 || !strlen(glob)))
                glob = NULL;
        else if (glob) {
                int not;

                type = filter_parse_regex(glob, strlen(glob), &search, &not);
                len = strlen(search);

                /* we do not support '!' for function probes */
                if (WARN_ON(not))
                        return;
        }

        mutex_lock(&ftrace_lock);
        for (i = 0; i < FTRACE_FUNC_HASHSIZE; i++) {
                struct hlist_head *hhd = &ftrace_func_hash[i];

                hlist_for_each_entry_safe(entry, n, tmp, hhd, node) {

                        /* break up if statements for readability */
                        if ((flags & PROBE_TEST_FUNC) && entry->ops != ops)
                                continue;

                        if ((flags & PROBE_TEST_DATA) && entry->data != data)
                                continue;

                        /* do this last, since it is the most expensive */
                        if (glob) {
                                kallsyms_lookup(entry->ip, NULL, NULL,
                                                NULL, str);
                                if (!ftrace_match(str, glob, len, type))
                                        continue;
                        }

                        hlist_del(&entry->node);
                        call_rcu(&entry->rcu, ftrace_free_entry_rcu);
                }
        }
        __disable_ftrace_function_probe();
        mutex_unlock(&ftrace_lock);
}

void
unregister_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
                                void *data)
{
        __unregister_ftrace_function_probe(glob, ops, data,
                                          PROBE_TEST_FUNC | PROBE_TEST_DATA);
}

void
unregister_ftrace_function_probe_func(char *glob, struct ftrace_probe_ops *ops)
{
        __unregister_ftrace_function_probe(glob, ops, NULL, PROBE_TEST_FUNC);
}

void unregister_ftrace_function_probe_all(char *glob)
{
        __unregister_ftrace_function_probe(glob, NULL, NULL, 0);
}

static LIST_HEAD(ftrace_commands);
static DEFINE_MUTEX(ftrace_cmd_mutex);

int register_ftrace_command(struct ftrace_func_command *cmd)
{
        struct ftrace_func_command *p;
        int ret = 0;

        mutex_lock(&ftrace_cmd_mutex);
        list_for_each_entry(p, &ftrace_commands, list) {
                if (strcmp(cmd->name, p->name) == 0) {
                        ret = -EBUSY;
                        goto out_unlock;
                }
        }
        list_add(&cmd->list, &ftrace_commands);
 out_unlock:
        mutex_unlock(&ftrace_cmd_mutex);

        return ret;
}

int unregister_ftrace_command(struct ftrace_func_command *cmd)
{
        struct ftrace_func_command *p, *n;
        int ret = -ENODEV;

        mutex_lock(&ftrace_cmd_mutex);
        list_for_each_entry_safe(p, n, &ftrace_commands, list) {
                if (strcmp(cmd->name, p->name) == 0) {
                        ret = 0;
                        list_del_init(&p->list);
                        goto out_unlock;
                }
        }
 out_unlock:
        mutex_unlock(&ftrace_cmd_mutex);

        return ret;
}

static int ftrace_process_regex(char *buff, int len, int enable)
{
        char *func, *command, *next = buff;
        struct ftrace_func_command *p;
        int ret = -EINVAL;

        func = strsep(&next, ":");

        if (!next) {
                ftrace_match_records(func, len, enable);
                return 0;
        }

        /* command found */

        command = strsep(&next, ":");

        mutex_lock(&ftrace_cmd_mutex);
        list_for_each_entry(p, &ftrace_commands, list) {
                if (strcmp(p->name, command) == 0) {
                        ret = p->func(func, command, next, enable);
                        goto out_unlock;
                }
        }
 out_unlock:
        mutex_unlock(&ftrace_cmd_mutex);

        return ret;
}

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;
        struct trace_parser *parser;
        ssize_t ret, read;

        if (!cnt)
                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;

        parser = &iter->parser;
        read = trace_get_user(parser, ubuf, cnt, ppos);

        if (read >= 0 && trace_parser_loaded(parser) &&
            !trace_parser_cont(parser)) {
                ret = ftrace_process_regex(parser->buffer,
                                           parser->idx, enable);
                if (ret)
                        goto out;

                trace_parser_clear(parser);
        }

        ret = read;

        mutex_unlock(&ftrace_regex_lock);
out:
        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_records(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);
}

/*
 * command line interface to allow users to set filters on boot up.
 */
#define FTRACE_FILTER_SIZE              COMMAND_LINE_SIZE
static char ftrace_notrace_buf[FTRACE_FILTER_SIZE] __initdata;
static char ftrace_filter_buf[FTRACE_FILTER_SIZE] __initdata;

static int __init set_ftrace_notrace(char *str)
{
        strncpy(ftrace_notrace_buf, str, FTRACE_FILTER_SIZE);
        return 1;
}
__setup("ftrace_notrace=", set_ftrace_notrace);

static int __init set_ftrace_filter(char *str)
{
        strncpy(ftrace_filter_buf, str, FTRACE_FILTER_SIZE);
        return 1;
}
__setup("ftrace_filter=", set_ftrace_filter);

static void __init set_ftrace_early_filter(char *buf, int enable)
{
        char *func;

        while (buf) {
                func = strsep(&buf, ",");
                ftrace_set_regex(func, strlen(func), 0, enable);
        }
}

static void __init set_ftrace_early_filters(void)
{
        if (ftrace_filter_buf[0])
                set_ftrace_early_filter(ftrace_filter_buf, 1);
        if (ftrace_notrace_buf[0])
                set_ftrace_early_filter(ftrace_notrace_buf, 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;
        struct trace_parser *parser;

        mutex_lock(&ftrace_regex_lock);
        if (file->f_mode & FMODE_READ) {
                iter = m->private;

                seq_release(inode, file);
        } else
                iter = file->private_data;

        parser = &iter->parser;
        if (trace_parser_loaded(parser)) {
                parser->buffer[parser->idx] = 0;
                ftrace_match_records(parser->buffer, parser->idx, enable);
        }

        mutex_lock(&ftrace_lock);
        if (ftrace_start_up && ftrace_enabled)
                ftrace_run_update_code(FTRACE_ENABLE_CALLS);
        mutex_unlock(&ftrace_lock);

        trace_parser_put(parser);
        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 const struct file_operations ftrace_avail_fops = {
        .open = ftrace_avail_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = seq_release_private,
};

static const struct file_operations ftrace_failures_fops = {
        .open = ftrace_failures_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = seq_release_private,
};

static const struct file_operations ftrace_filter_fops = {
        .open = ftrace_filter_open,
        .read = seq_read,
        .write = ftrace_filter_write,
        .llseek = ftrace_regex_lseek,
        .release = ftrace_filter_release,
};

static const struct file_operations ftrace_notrace_fops = {
        .open = ftrace_notrace_open,
        .read = seq_read,
        .write = ftrace_notrace_write,
        .llseek = ftrace_regex_lseek,
        .release = ftrace_notrace_release,
};

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

static DEFINE_MUTEX(graph_lock);

int ftrace_graph_count;
unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;

static void *
__g_next(struct seq_file *m, loff_t *pos)
{
        if (*pos >= ftrace_graph_count)
                return NULL;
        return &ftrace_graph_funcs[*pos];
}

static void *
g_next(struct seq_file *m, void *v, loff_t *pos)
{
        (*pos)++;
        return __g_next(m, pos);
}

static void *g_start(struct seq_file *m, loff_t *pos)
{
        mutex_lock(&graph_lock);

        /* Nothing, tell g_show to print all functions are enabled */
        if (!ftrace_graph_count && !*pos)
                return (void *)1;

        return __g_next(m, pos);
}

static void g_stop(struct seq_file *m, void *p)
{
        mutex_unlock(&graph_lock);
}

static int g_show(struct seq_file *m, void *v)
{
        unsigned long *ptr = v;

        if (!ptr)
                return 0;

        if (ptr == (unsigned long *)1) {
                seq_printf(m, "#### all functions enabled ####\n");
                return 0;
        }

        seq_printf(m, "%ps\n", (void *)*ptr);

        return 0;
}

static const struct seq_operations ftrace_graph_seq_ops = {
        .start = g_start,
        .next = g_next,
        .stop = g_stop,
        .show = g_show,
};

static int
ftrace_graph_open(struct inode *inode, struct file *file)
{
        int ret = 0;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        mutex_lock(&graph_lock);
        if ((file->f_mode & FMODE_WRITE) &&
            (file->f_flags & O_TRUNC)) {
                ftrace_graph_count = 0;
                memset(ftrace_graph_funcs, 0, sizeof(ftrace_graph_funcs));
        }
        mutex_unlock(&graph_lock);

        if (file->f_mode & FMODE_READ)
                ret = seq_open(file, &ftrace_graph_seq_ops);

        return ret;
}

static int
ftrace_graph_release(struct inode *inode, struct file *file)
{
        if (file->f_mode & FMODE_READ)
                seq_release(inode, file);
        return 0;
}

static int
ftrace_set_func(unsigned long *array, int *idx, char *buffer)
{
        struct dyn_ftrace *rec;
        struct ftrace_page *pg;
        int search_len;
        int found = 0;
        int type, not;
        char *search;
        bool exists;
        int i;

        if (ftrace_disabled)
                return -ENODEV;

        /* decode regex */
        type = filter_parse_regex(buffer, strlen(buffer), &search, &not);
        if (not)
                return -EINVAL;

        search_len = strlen(search);

        mutex_lock(&ftrace_lock);
        do_for_each_ftrace_rec(pg, rec) {

                if (*idx >= FTRACE_GRAPH_MAX_FUNCS)
                        break;

                if (rec->flags & (FTRACE_FL_FAILED | FTRACE_FL_FREE))
                        continue;

                if (ftrace_match_record(rec, search, search_len, type)) {
                        /* ensure it is not already in the array */
                        exists = false;
                        for (i = 0; i < *idx; i++)
                                if (array[i] == rec->ip) {
                                        exists = true;
                                        break;
                                }
                        if (!exists) {
                                array[(*idx)++] = rec->ip;
                                found = 1;
                        }
                }
        } while_for_each_ftrace_rec();

        mutex_unlock(&ftrace_lock);

        return found ? 0 : -EINVAL;
}

static ssize_t
ftrace_graph_write(struct file *file, const char __user *ubuf,
                   size_t cnt, loff_t *ppos)
{
        struct trace_parser parser;
        ssize_t read, ret;

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

        mutex_lock(&graph_lock);

        if (ftrace_graph_count >= FTRACE_GRAPH_MAX_FUNCS) {
                ret = -EBUSY;
                goto out_unlock;
        }

        if (trace_parser_get_init(&parser, FTRACE_BUFF_MAX)) {
                ret = -ENOMEM;
                goto out_unlock;
        }

        read = trace_get_user(&parser, ubuf, cnt, ppos);

        if (read >= 0 && trace_parser_loaded((&parser))) {
                parser.buffer[parser.idx] = 0;

                /* we allow only one expression at a time */
                ret = ftrace_set_func(ftrace_graph_funcs, &ftrace_graph_count,
                                        parser.buffer);
                if (ret)
                        goto out_free;
        }

        ret = read;

out_free:
        trace_parser_put(&parser);
out_unlock:
        mutex_unlock(&graph_lock);

        return ret;
}

static const struct file_operations ftrace_graph_fops = {
        .open           = ftrace_graph_open,
        .read           = seq_read,
        .write          = ftrace_graph_write,
        .release        = ftrace_graph_release,
};
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer)
{

        trace_create_file("available_filter_functions", 0444,
                        d_tracer, NULL, &ftrace_avail_fops);

        trace_create_file("failures", 0444,
                        d_tracer, NULL, &ftrace_failures_fops);

        trace_create_file("set_ftrace_filter", 0644, d_tracer,
                        NULL, &ftrace_filter_fops);

        trace_create_file("set_ftrace_notrace", 0644, d_tracer,
                                    NULL, &ftrace_notrace_fops);

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        trace_create_file("set_graph_function", 0444, d_tracer,
                                    NULL,
                                    &ftrace_graph_fops);
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

        return 0;
}

static int ftrace_convert_nops(struct module *mod,
                               unsigned long *start,
                               unsigned long *end)
{
        unsigned long *p;
        unsigned long addr;
        unsigned long flags;

        mutex_lock(&ftrace_lock);
        p = start;
        while (p < end) {
                addr = ftrace_call_adjust(*p++);
                /*
                 * Some architecture linkers will pad between
                 * the different mcount_loc sections of different
                 * object files to satisfy alignments.
                 * Skip any NULL pointers.
                 */
                if (!addr)
                        continue;
                ftrace_record_ip(addr);
        }

        /* disable interrupts to prevent kstop machine */
        local_irq_save(flags);
        ftrace_update_code(mod);
        local_irq_restore(flags);
        mutex_unlock(&ftrace_lock);

        return 0;
}

#ifdef CONFIG_MODULES
void ftrace_release_mod(struct module *mod)
{
        struct dyn_ftrace *rec;
        struct ftrace_page *pg;

        if (ftrace_disabled)
                return;

        mutex_lock(&ftrace_lock);
        do_for_each_ftrace_rec(pg, rec) {
                if (within_module_core(rec->ip, mod)) {
                        /*
                         * rec->ip is changed in ftrace_free_rec()
                         * It should not between s and e if record was freed.
                         */
                        FTRACE_WARN_ON(rec->flags & FTRACE_FL_FREE);
                        ftrace_free_rec(rec);
                }
        } while_for_each_ftrace_rec();
        mutex_unlock(&ftrace_lock);
}

static void ftrace_init_module(struct module *mod,
                               unsigned long *start, unsigned long *end)
{
        if (ftrace_disabled || start == end)
                return;
        ftrace_convert_nops(mod, start, end);
}

static int ftrace_module_notify(struct notifier_block *self,
                                unsigned long val, void *data)
{
        struct module *mod = data;

        switch (val) {
        case MODULE_STATE_COMING:
                ftrace_init_module(mod, mod->ftrace_callsites,
                                   mod->ftrace_callsites +
                                   mod->num_ftrace_callsites);
                break;
        case MODULE_STATE_GOING:
                ftrace_release_mod(mod);
                break;
        }

        return 0;
}
#else
static int ftrace_module_notify(struct notifier_block *self,
                                unsigned long val, void *data)
{
        return 0;
}
#endif /* CONFIG_MODULES */

struct notifier_block ftrace_module_nb = {
        .notifier_call = ftrace_module_notify,
        .priority = 0,
};

extern unsigned long __start_mcount_loc[];
extern unsigned long __stop_mcount_loc[];

void __init ftrace_init(void)
{
        unsigned long count, addr, flags;
        int ret;

        /* Keep the ftrace pointer to the stub */
        addr = (unsigned long)ftrace_stub;

        local_irq_save(flags);
        ftrace_dyn_arch_init(&addr);
        local_irq_restore(flags);

        /* ftrace_dyn_arch_init places the return code in addr */
        if (addr)
                goto failed;

        count = __stop_mcount_loc - __start_mcount_loc;

        ret = ftrace_dyn_table_alloc(count);
        if (ret)
                goto failed;

        last_ftrace_enabled = ftrace_enabled = 1;

        ret = ftrace_convert_nops(NULL,
                                  __start_mcount_loc,
                                  __stop_mcount_loc);

        ret = register_module_notifier(&ftrace_module_nb);
        if (ret)
                pr_warning("Failed to register trace ftrace module notifier\n");

        set_ftrace_early_filters();

        return;
 failed:
        ftrace_disabled = 1;
}

#else

static int __init ftrace_nodyn_init(void)
{
        ftrace_enabled = 1;
        return 0;
}
device_initcall(ftrace_nodyn_init);

static inline int ftrace_init_dyn_debugfs(struct dentry *d_tracer) { return 0; }
static inline void ftrace_startup_enable(int command) { }
/* Keep as macros so we do not need to define the commands */
# define ftrace_startup(command)        do { } while (0)
# define ftrace_shutdown(command)       do { } while (0)
# define ftrace_startup_sysctl()        do { } while (0)
# define ftrace_shutdown_sysctl()       do { } while (0)
#endif /* CONFIG_DYNAMIC_FTRACE */

static ssize_t
ftrace_pid_read(struct file *file, char __user *ubuf,
                       size_t cnt, loff_t *ppos)
{
        char buf[64];
        int r;

        if (ftrace_pid_trace == ftrace_swapper_pid)
                r = sprintf(buf, "swapper tasks\n");
        else if (ftrace_pid_trace)
                r = sprintf(buf, "%u\n", pid_vnr(ftrace_pid_trace));
        else
                r = sprintf(buf, "no pid\n");

        return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}

static void clear_ftrace_swapper(void)
{
        struct task_struct *p;
        int cpu;

        get_online_cpus();
        for_each_online_cpu(cpu) {
                p = idle_task(cpu);
                clear_tsk_trace_trace(p);
        }
        put_online_cpus();
}

static void set_ftrace_swapper(void)
{
        struct task_struct *p;
        int cpu;

        get_online_cpus();
        for_each_online_cpu(cpu) {
                p = idle_task(cpu);
                set_tsk_trace_trace(p);
        }
        put_online_cpus();
}

static void clear_ftrace_pid(struct pid *pid)
{
        struct task_struct *p;

        rcu_read_lock();
        do_each_pid_task(pid, PIDTYPE_PID, p) {
                clear_tsk_trace_trace(p);
        } while_each_pid_task(pid, PIDTYPE_PID, p);
        rcu_read_unlock();

        put_pid(pid);
}

static void set_ftrace_pid(struct pid *pid)
{
        struct task_struct *p;

        rcu_read_lock();
        do_each_pid_task(pid, PIDTYPE_PID, p) {
                set_tsk_trace_trace(p);
        } while_each_pid_task(pid, PIDTYPE_PID, p);
        rcu_read_unlock();
}

static void clear_ftrace_pid_task(struct pid **pid)
{
        if (*pid == ftrace_swapper_pid)
                clear_ftrace_swapper();
        else
                clear_ftrace_pid(*pid);

        *pid = NULL;
}

static void set_ftrace_pid_task(struct pid *pid)
{
        if (pid == ftrace_swapper_pid)
                set_ftrace_swapper();
        else
                set_ftrace_pid(pid);
}

static ssize_t
ftrace_pid_write(struct file *filp, const char __user *ubuf,
                   size_t cnt, loff_t *ppos)
{
        struct pid *pid;
        char buf[64];
        long val;
        int ret;

        if (cnt >= sizeof(buf))
                return -EINVAL;

        if (copy_from_user(&buf, ubuf, cnt))
                return -EFAULT;

        buf[cnt] = 0;

        ret = strict_strtol(buf, 10, &val);
        if (ret < 0)
                return ret;

        mutex_lock(&ftrace_lock);
        if (val < 0) {
                /* disable pid tracing */
                if (!ftrace_pid_trace)
                        goto out;

                clear_ftrace_pid_task(&ftrace_pid_trace);

        } else {
                /* swapper task is special */
                if (!val) {
                        pid = ftrace_swapper_pid;
                        if (pid == ftrace_pid_trace)
                                goto out;
                } else {
                        pid = find_get_pid(val);

                        if (pid == ftrace_pid_trace) {
                                put_pid(pid);
                                goto out;
                        }
                }

                if (ftrace_pid_trace)
                        clear_ftrace_pid_task(&ftrace_pid_trace);

                if (!pid)
                        goto out;

                ftrace_pid_trace = pid;

                set_ftrace_pid_task(ftrace_pid_trace);
        }

        /* update the function call */
        ftrace_update_pid_func();
        ftrace_startup_enable(0);

 out:
        mutex_unlock(&ftrace_lock);

        return cnt;
}

static const struct file_operations ftrace_pid_fops = {
        .read = ftrace_pid_read,
        .write = ftrace_pid_write,
};

static __init int ftrace_init_debugfs(void)
{
        struct dentry *d_tracer;

        d_tracer = tracing_init_dentry();
        if (!d_tracer)
                return 0;

        ftrace_init_dyn_debugfs(d_tracer);

        trace_create_file("set_ftrace_pid", 0644, d_tracer,
                            NULL, &ftrace_pid_fops);

        ftrace_profile_debugfs(d_tracer);

        return 0;
}
fs_initcall(ftrace_init_debugfs);

/**
 * ftrace_kill - kill ftrace
 *
 * 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(void)
{
        ftrace_disabled = 1;
        ftrace_enabled = 0;
        clear_ftrace_function();
}

/**
 * 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_lock);

        ret = __register_ftrace_function(ops);
        ftrace_startup(0);

        mutex_unlock(&ftrace_lock);
        return ret;
}

/**
 * unregister_ftrace_function - unregister 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_lock);
        ret = __unregister_ftrace_function(ops);
        ftrace_shutdown(0);
        mutex_unlock(&ftrace_lock);

        return ret;
}

int
ftrace_enable_sysctl(struct ctl_table *table, int write,
                     void __user *buffer, size_t *lenp,
                     loff_t *ppos)
{
        int ret;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        mutex_lock(&ftrace_lock);

        ret  = proc_dointvec(table, write, 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_lock);
        return ret;
}

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

static int ftrace_graph_active;
static struct notifier_block ftrace_suspend_notifier;

int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
{
        return 0;
}

/* The callbacks that hook a function */
trace_func_graph_ret_t ftrace_graph_return =
                        (trace_func_graph_ret_t)ftrace_stub;
trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub;

/* Try to assign a return stack array on FTRACE_RETSTACK_ALLOC_SIZE tasks. */
static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list)
{
        int i;
        int ret = 0;
        unsigned long flags;
        int start = 0, end = FTRACE_RETSTACK_ALLOC_SIZE;
        struct task_struct *g, *t;

        for (i = 0; i < FTRACE_RETSTACK_ALLOC_SIZE; i++) {
                ret_stack_list[i] = kmalloc(FTRACE_RETFUNC_DEPTH
                                        * sizeof(struct ftrace_ret_stack),
                                        GFP_KERNEL);
                if (!ret_stack_list[i]) {
                        start = 0;
                        end = i;
                        ret = -ENOMEM;
                        goto free;
                }
        }

        read_lock_irqsave(&tasklist_lock, flags);
        do_each_thread(g, t) {
                if (start == end) {
                        ret = -EAGAIN;
                        goto unlock;
                }

                if (t->ret_stack == NULL) {
                        atomic_set(&t->tracing_graph_pause, 0);
                        atomic_set(&t->trace_overrun, 0);
                        t->curr_ret_stack = -1;
                        /* Make sure the tasks see the -1 first: */
                        smp_wmb();
                        t->ret_stack = ret_stack_list[start++];
                }
        } while_each_thread(g, t);

unlock:
        read_unlock_irqrestore(&tasklist_lock, flags);
free:
        for (i = start; i < end; i++)
                kfree(ret_stack_list[i]);
        return ret;
}

static void
ftrace_graph_probe_sched_switch(struct rq *__rq, struct task_struct *prev,
                                struct task_struct *next)
{
        unsigned long long timestamp;
        int index;

        /*
         * Does the user want to count the time a function was asleep.
         * If so, do not update the time stamps.
         */
        if (trace_flags & TRACE_ITER_SLEEP_TIME)
                return;

        timestamp = trace_clock_local();

        prev->ftrace_timestamp = timestamp;

        /* only process tasks that we timestamped */
        if (!next->ftrace_timestamp)
                return;

        /*
         * Update all the counters in next to make up for the
         * time next was sleeping.
         */
        timestamp -= next->ftrace_timestamp;

        for (index = next->curr_ret_stack; index >= 0; index--)
                next->ret_stack[index].calltime += timestamp;
}

/* Allocate a return stack for each task */
static int start_graph_tracing(void)
{
        struct ftrace_ret_stack **ret_stack_list;
        int ret, cpu;

        ret_stack_list = kmalloc(FTRACE_RETSTACK_ALLOC_SIZE *
                                sizeof(struct ftrace_ret_stack *),
                                GFP_KERNEL);

        if (!ret_stack_list)
                return -ENOMEM;

        /* The cpu_boot init_task->ret_stack will never be freed */
        for_each_online_cpu(cpu) {
                if (!idle_task(cpu)->ret_stack)
                        ftrace_graph_init_task(idle_task(cpu));
        }

        do {
                ret = alloc_retstack_tasklist(ret_stack_list);
        } while (ret == -EAGAIN);

        if (!ret) {
                ret = register_trace_sched_switch(ftrace_graph_probe_sched_switch);
                if (ret)
                        pr_info("ftrace_graph: Couldn't activate tracepoint"
                                " probe to kernel_sched_switch\n");
        }

        kfree(ret_stack_list);
        return ret;
}

/*
 * Hibernation protection.
 * The state of the current task is too much unstable during
 * suspend/restore to disk. We want to protect against that.
 */
static int
ftrace_suspend_notifier_call(struct notifier_block *bl, unsigned long state,
                                                        void *unused)
{
        switch (state) {
        case PM_HIBERNATION_PREPARE:
                pause_graph_tracing();
                break;

        case PM_POST_HIBERNATION:
                unpause_graph_tracing();
                break;
        }
        return NOTIFY_DONE;
}

int register_ftrace_graph(trace_func_graph_ret_t retfunc,
                        trace_func_graph_ent_t entryfunc)
{
        int ret = 0;

        mutex_lock(&ftrace_lock);

        /* we currently allow only one tracer registered at a time */
        if (ftrace_graph_active) {
                ret = -EBUSY;
                goto out;
        }

        ftrace_suspend_notifier.notifier_call = ftrace_suspend_notifier_call;
        register_pm_notifier(&ftrace_suspend_notifier);

        ftrace_graph_active++;
        ret = start_graph_tracing();
        if (ret) {
                ftrace_graph_active--;
                goto out;
        }

        ftrace_graph_return = retfunc;
        ftrace_graph_entry = entryfunc;

        ftrace_startup(FTRACE_START_FUNC_RET);

out:
        mutex_unlock(&ftrace_lock);
        return ret;
}

void unregister_ftrace_graph(void)
{
        mutex_lock(&ftrace_lock);

        if (unlikely(!ftrace_graph_active))
                goto out;

        ftrace_graph_active--;
        unregister_trace_sched_switch(ftrace_graph_probe_sched_switch);
        ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
        ftrace_graph_entry = ftrace_graph_entry_stub;
        ftrace_shutdown(FTRACE_STOP_FUNC_RET);
        unregister_pm_notifier(&ftrace_suspend_notifier);

 out:
        mutex_unlock(&ftrace_lock);
}

/* Allocate a return stack for newly created task */
void ftrace_graph_init_task(struct task_struct *t)
{
        /* Make sure we do not use the parent ret_stack */
        t->ret_stack = NULL;

        if (ftrace_graph_active) {
                struct ftrace_ret_stack *ret_stack;

                ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH
                                * sizeof(struct ftrace_ret_stack),
                                GFP_KERNEL);
                if (!ret_stack)
                        return;
                t->curr_ret_stack = -1;
                atomic_set(&t->tracing_graph_pause, 0);
                atomic_set(&t->trace_overrun, 0);
                t->ftrace_timestamp = 0;
                /* make curr_ret_stack visable before we add the ret_stack */
                smp_wmb();
                t->ret_stack = ret_stack;
        }
}

void ftrace_graph_exit_task(struct task_struct *t)
{
        struct ftrace_ret_stack *ret_stack = t->ret_stack;

        t->ret_stack = NULL;
        /* NULL must become visible to IRQs before we free it: */
        barrier();

        kfree(ret_stack);
}

void ftrace_graph_stop(void)
{
        ftrace_stop();
}
#endif