Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux

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

/*
 * Infrastructure for profiling code inserted by 'gcc -pg'.
 *
 * Copyright (C) 2007-2008 Steven Rostedt <[email protected]>
 * Copyright (C) 2004-2008 Ingo Molnar <[email protected]>
 *
 * Originally ported from the -rt patch by:
 *   Copyright (C) 2007 Arnaldo Carvalho de Melo <[email protected]>
 *
 * Based on code in the latency_tracer, that is:
 *
 *  Copyright (C) 2004-2006 Ingo Molnar
 *  Copyright (C) 2004 Nadia Yvette Chambers
 */

#include <linux/stop_machine.h>
#include <linux/clocksource.h>
#include <linux/kallsyms.h>
#include <linux/seq_file.h>
#include <linux/suspend.h>
#include <linux/tracefs.h>
#include <linux/hardirq.h>
#include <linux/kthread.h>
#include <linux/uaccess.h>
#include <linux/bsearch.h>
#include <linux/module.h>
#include <linux/ftrace.h>
#include <linux/sysctl.h>
#include <linux/slab.h>
#include <linux/ctype.h>
#include <linux/sort.h>
#include <linux/list.h>
#include <linux/hash.h>
#include <linux/rcupdate.h>

#include <trace/events/sched.h>

#include <asm/setup.h>

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

#define FTRACE_WARN_ON(cond)                    \
        ({                                      \
                int ___r = cond;                \
                if (WARN_ON(___r))              \
                        ftrace_kill();          \
                ___r;                           \
        })

#define FTRACE_WARN_ON_ONCE(cond)               \
        ({                                      \
                int ___r = cond;                \
                if (WARN_ON_ONCE(___r))         \
                        ftrace_kill();          \
                ___r;                           \
        })

/* hash bits for specific function selection */
#define FTRACE_HASH_BITS 7
#define FTRACE_FUNC_HASHSIZE (1 << FTRACE_HASH_BITS)
#define FTRACE_HASH_DEFAULT_BITS 10
#define FTRACE_HASH_MAX_BITS 12

#ifdef CONFIG_DYNAMIC_FTRACE
#define INIT_OPS_HASH(opsname)  \
        .func_hash              = &opsname.local_hash,                  \
        .local_hash.regex_lock  = __MUTEX_INITIALIZER(opsname.local_hash.regex_lock),
#define ASSIGN_OPS_HASH(opsname, val) \
        .func_hash              = val, \
        .local_hash.regex_lock  = __MUTEX_INITIALIZER(opsname.local_hash.regex_lock),
#else
#define INIT_OPS_HASH(opsname)
#define ASSIGN_OPS_HASH(opsname, val)
#endif

static struct ftrace_ops ftrace_list_end __read_mostly = {
        .func           = ftrace_stub,
        .flags          = FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_STUB,
        INIT_OPS_HASH(ftrace_list_end)
};

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

/* Current function tracing op */
struct ftrace_ops *function_trace_op __read_mostly = &ftrace_list_end;
/* What to set function_trace_op to */
static struct ftrace_ops *set_function_trace_op;

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

static bool ftrace_pids_enabled(void)
{
        return !list_empty(&ftrace_pids);
}

static void ftrace_update_trampoline(struct ftrace_ops *ops);

/*
 * 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_ops_list __read_mostly = &ftrace_list_end;
ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
static struct ftrace_ops global_ops;

#if ARCH_SUPPORTS_FTRACE_OPS
static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
                                 struct ftrace_ops *op, struct pt_regs *regs);
#else
/* See comment below, where ftrace_ops_list_func is defined */
static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip);
#define ftrace_ops_list_func ((ftrace_func_t)ftrace_ops_no_ops)
#endif

/*
 * Traverse the ftrace_global_list, invoking all entries.  The reason that we
 * can use rcu_dereference_raw_notrace() is that elements removed from this list
 * are simply leaked, so there is no need to interact with a grace-period
 * mechanism.  The rcu_dereference_raw_notrace() calls are needed to handle
 * concurrent insertions into the ftrace_global_list.
 *
 * Silly Alpha and silly pointer-speculation compiler optimizations!
 */
#define do_for_each_ftrace_op(op, list)                 \
        op = rcu_dereference_raw_notrace(list);                 \
        do

/*
 * Optimized for just a single item in the list (as that is the normal case).
 */
#define while_for_each_ftrace_op(op)                            \
        while (likely(op = rcu_dereference_raw_notrace((op)->next)) &&  \
               unlikely((op) != &ftrace_list_end))

static inline void ftrace_ops_init(struct ftrace_ops *ops)
{
#ifdef CONFIG_DYNAMIC_FTRACE
        if (!(ops->flags & FTRACE_OPS_FL_INITIALIZED)) {
                mutex_init(&ops->local_hash.regex_lock);
                ops->func_hash = &ops->local_hash;
                ops->flags |= FTRACE_OPS_FL_INITIALIZED;
        }
#endif
}

/**
 * ftrace_nr_registered_ops - return number of ops registered
 *
 * Returns the number of ftrace_ops registered and tracing functions
 */
int ftrace_nr_registered_ops(void)
{
        struct ftrace_ops *ops;
        int cnt = 0;

        mutex_lock(&ftrace_lock);

        for (ops = ftrace_ops_list;
             ops != &ftrace_list_end; ops = ops->next)
                cnt++;

        mutex_unlock(&ftrace_lock);

        return cnt;
}

static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip,
                            struct ftrace_ops *op, struct pt_regs *regs)
{
        if (!test_tsk_trace_trace(current))
                return;

        op->saved_func(ip, parent_ip, op, regs);
}

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

static void per_cpu_ops_disable_all(struct ftrace_ops *ops)
{
        int cpu;

        for_each_possible_cpu(cpu)
                *per_cpu_ptr(ops->disabled, cpu) = 1;
}

static int per_cpu_ops_alloc(struct ftrace_ops *ops)
{
        int __percpu *disabled;

        if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_PER_CPU)))
                return -EINVAL;

        disabled = alloc_percpu(int);
        if (!disabled)
                return -ENOMEM;

        ops->disabled = disabled;
        per_cpu_ops_disable_all(ops);
        return 0;
}

static void ftrace_sync(struct work_struct *work)
{
        /*
         * This function is just a stub to implement a hard force
         * of synchronize_sched(). This requires synchronizing
         * tasks even in userspace and idle.
         *
         * Yes, function tracing is rude.
         */
}

static void ftrace_sync_ipi(void *data)
{
        /* Probably not needed, but do it anyway */
        smp_rmb();
}

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static void update_function_graph_func(void);

/* Both enabled by default (can be cleared by function_graph tracer flags */
static bool fgraph_sleep_time = true;
static bool fgraph_graph_time = true;

#else
static inline void update_function_graph_func(void) { }
#endif


static ftrace_func_t ftrace_ops_get_list_func(struct ftrace_ops *ops)
{
        /*
         * If this is a dynamic, RCU, or per CPU ops, or we force list func,
         * then it needs to call the list anyway.
         */
        if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_PER_CPU |
                          FTRACE_OPS_FL_RCU) || FTRACE_FORCE_LIST_FUNC)
                return ftrace_ops_list_func;

        return ftrace_ops_get_func(ops);
}

static void update_ftrace_function(void)
{
        ftrace_func_t func;

        /*
         * Prepare the ftrace_ops that the arch callback will use.
         * If there's only one ftrace_ops registered, the ftrace_ops_list
         * will point to the ops we want.
         */
        set_function_trace_op = ftrace_ops_list;

        /* If there's no ftrace_ops registered, just call the stub function */
        if (ftrace_ops_list == &ftrace_list_end) {
                func = ftrace_stub;

        /*
         * If we are at the end of the list and this ops is
         * recursion safe and not dynamic and the arch supports passing ops,
         * then have the mcount trampoline call the function directly.
         */
        } else if (ftrace_ops_list->next == &ftrace_list_end) {
                func = ftrace_ops_get_list_func(ftrace_ops_list);

        } else {
                /* Just use the default ftrace_ops */
                set_function_trace_op = &ftrace_list_end;
                func = ftrace_ops_list_func;
        }

        update_function_graph_func();

        /* If there's no change, then do nothing more here */
        if (ftrace_trace_function == func)
                return;

        /*
         * If we are using the list function, it doesn't care
         * about the function_trace_ops.
         */
        if (func == ftrace_ops_list_func) {
                ftrace_trace_function = func;
                /*
                 * Don't even bother setting function_trace_ops,
                 * it would be racy to do so anyway.
                 */
                return;
        }

#ifndef CONFIG_DYNAMIC_FTRACE
        /*
         * For static tracing, we need to be a bit more careful.
         * The function change takes affect immediately. Thus,
         * we need to coorditate the setting of the function_trace_ops
         * with the setting of the ftrace_trace_function.
         *
         * Set the function to the list ops, which will call the
         * function we want, albeit indirectly, but it handles the
         * ftrace_ops and doesn't depend on function_trace_op.
         */
        ftrace_trace_function = ftrace_ops_list_func;
        /*
         * Make sure all CPUs see this. Yes this is slow, but static
         * tracing is slow and nasty to have enabled.
         */
        schedule_on_each_cpu(ftrace_sync);
        /* Now all cpus are using the list ops. */
        function_trace_op = set_function_trace_op;
        /* Make sure the function_trace_op is visible on all CPUs */
        smp_wmb();
        /* Nasty way to force a rmb on all cpus */
        smp_call_function(ftrace_sync_ipi, NULL, 1);
        /* OK, we are all set to update the ftrace_trace_function now! */
#endif /* !CONFIG_DYNAMIC_FTRACE */

        ftrace_trace_function = func;
}

int using_ftrace_ops_list_func(void)
{
        return ftrace_trace_function == ftrace_ops_list_func;
}

static void add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
{
        ops->next = *list;
        /*
         * We are entering ops into the list but another
         * CPU might be walking that list. We need to make sure
         * the ops->next pointer is valid before another CPU sees
         * the ops pointer included into the list.
         */
        rcu_assign_pointer(*list, ops);
}

static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
{
        struct ftrace_ops **p;

        /*
         * If we are removing the last function, then simply point
         * to the ftrace_stub.
         */
        if (*list == ops && ops->next == &ftrace_list_end) {
                *list = &ftrace_list_end;
                return 0;
        }

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

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

        *p = (*p)->next;
        return 0;
}

static void ftrace_update_trampoline(struct ftrace_ops *ops);

static int __register_ftrace_function(struct ftrace_ops *ops)
{
        if (ops->flags & FTRACE_OPS_FL_DELETED)
                return -EINVAL;

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

#ifndef CONFIG_DYNAMIC_FTRACE_WITH_REGS
        /*
         * If the ftrace_ops specifies SAVE_REGS, then it only can be used
         * if the arch supports it, or SAVE_REGS_IF_SUPPORTED is also set.
         * Setting SAVE_REGS_IF_SUPPORTED makes SAVE_REGS irrelevant.
         */
        if (ops->flags & FTRACE_OPS_FL_SAVE_REGS &&
            !(ops->flags & FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED))
                return -EINVAL;

        if (ops->flags & FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED)
                ops->flags |= FTRACE_OPS_FL_SAVE_REGS;
#endif

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

        if (ops->flags & FTRACE_OPS_FL_PER_CPU) {
                if (per_cpu_ops_alloc(ops))
                        return -ENOMEM;
        }

        add_ftrace_ops(&ftrace_ops_list, ops);

        /* Always save the function, and reset at unregistering */
        ops->saved_func = ops->func;

        if (ops->flags & FTRACE_OPS_FL_PID && ftrace_pids_enabled())
                ops->func = ftrace_pid_func;

        ftrace_update_trampoline(ops);

        if (ftrace_enabled)
                update_ftrace_function();

        return 0;
}

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

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

        ret = remove_ftrace_ops(&ftrace_ops_list, ops);

        if (ret < 0)
                return ret;

        if (ftrace_enabled)
                update_ftrace_function();

        ops->func = ops->saved_func;

        return 0;
}

static void ftrace_update_pid_func(void)
{
        bool enabled = ftrace_pids_enabled();
        struct ftrace_ops *op;

        /* Only do something if we are tracing something */
        if (ftrace_trace_function == ftrace_stub)
                return;

        do_for_each_ftrace_op(op, ftrace_ops_list) {
                if (op->flags & FTRACE_OPS_FL_PID) {
                        op->func = enabled ? ftrace_pid_func :
                                op->saved_func;
                        ftrace_update_trampoline(op);
                }
        } while_for_each_ftrace_op(op);

        update_ftrace_function();
}

#ifdef CONFIG_FUNCTION_PROFILER
struct ftrace_profile {
        struct hlist_node               node;
        unsigned long                   ip;
        unsigned long                   counter;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        unsigned long long              time;
        unsigned long long              time_squared;
#endif
};

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

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

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

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

static int ftrace_profile_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_BITS 10
#define FTRACE_PROFILE_HASH_SIZE (1 << FTRACE_PROFILE_HASH_BITS)

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_puts(m, "  Function                               "
                 "Hit    Time            Avg             s^2\n"
                    "  --------                               "
                 "---    ----            ---             ---\n");
#else
        seq_puts(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];
        int ret = 0;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        static struct trace_seq s;
        unsigned long long avg;
        unsigned long long stddev;
#endif
        mutex_lock(&ftrace_profile_lock);

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

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        avg = rec->time;
        do_div(avg, rec->counter);
        if (tracing_thresh && (avg < tracing_thresh))
                goto out;
#endif

        kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
        seq_printf(m, "  %-30.30s  %10lu", str, rec->counter);

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        seq_puts(m, "    ");

        /* Sample standard deviation (s^2) */
        if (rec->counter <= 1)
                stddev = 0;
        else {
                /*
                 * Apply Welford's method:
                 * s^2 = 1 / (n * (n-1)) * (n * \Sum (x_i)^2 - (\Sum x_i)^2)
                 */
                stddev = rec->counter * rec->time_squared -
                         rec->time * rec->time;

                /*
                 * Divide only 1000 for ns^2 -> us^2 conversion.
                 * trace_print_graph_duration will divide 1000 again.
                 */
                do_div(stddev, rec->counter * (rec->counter - 1) * 1000);
        }

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

        return ret;
}

static void ftrace_profile_reset(struct ftrace_profile_stat *stat)
{
        struct ftrace_profile_page *pg;

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

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

        memset(stat->hash, 0,
               FTRACE_PROFILE_HASH_SIZE * sizeof(struct hlist_head));
}

int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)
{
        struct ftrace_profile_page *pg;
        int functions;
        int pages;
        int i;

        /* If we already allocated, do nothing */
        if (stat->pages)
                return 0;

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

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

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

        pages = DIV_ROUND_UP(functions, PROFILES_PER_PAGE);

        for (i = 1; 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);
        }

        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;

        /* 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_possible_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;
        unsigned long key;

        key = hash_long(ip, FTRACE_PROFILE_HASH_BITS);
        hhd = &stat->hash[key];

        if (hlist_empty(hhd))
                return NULL;

        hlist_for_each_entry_rcu_notrace(rec, 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_HASH_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_ops *ops, struct pt_regs *regs)
{
        struct ftrace_profile_stat *stat;
        struct ftrace_profile *rec;
        unsigned long flags;

        if (!ftrace_profile_enabled)
                return;

        local_irq_save(flags);

        stat = this_cpu_ptr(&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, NULL, NULL);
        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 = this_cpu_ptr(&ftrace_profile_stats);
        if (!stat->hash || !ftrace_profile_enabled)
                goto out;

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

        calltime = trace->rettime - trace->calltime;

        if (!fgraph_graph_time) {
                int index;

                index = trace->depth;

                /* Append this call time to the parent time to subtract */
                if (index)
                        current->ret_stack[index - 1].subtime += calltime;

                if (current->ret_stack[index].subtime < calltime)
                        calltime -= current->ret_stack[index].subtime;
                else
                        calltime = 0;
        }

        rec = ftrace_find_profiled_func(stat, trace->func);
        if (rec) {
                rec->time += calltime;
                rec->time_squared += calltime * calltime;
        }

 out:
        local_irq_restore(flags);
}

static int register_ftrace_profiler(void)
{
        return register_ftrace_graph(&profile_graph_return,
                                     &profile_graph_entry);
}

static void unregister_ftrace_profiler(void)
{
        unregister_ftrace_graph();
}
#else
static struct ftrace_ops ftrace_profile_ops __read_mostly = {
        .func           = function_profile_call,
        .flags          = FTRACE_OPS_FL_RECURSION_SAFE | FTRACE_OPS_FL_INITIALIZED,
        INIT_OPS_HASH(ftrace_profile_ops)
};

static int register_ftrace_profiler(void)
{
        return register_ftrace_function(&ftrace_profile_ops);
}

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

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

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

        val = !!val;

        mutex_lock(&ftrace_profile_lock);
        if (ftrace_profile_enabled ^ val) {
                if (val) {
                        ret = ftrace_profile_init();
                        if (ret < 0) {
                                cnt = ret;
                                goto out;
                        }

                        ret = register_ftrace_profiler();
                        if (ret < 0) {
                                cnt = ret;
                                goto out;
                        }
                        ftrace_profile_enabled = 1;
                } else {
                        ftrace_profile_enabled = 0;
                        /*
                         * unregister_ftrace_profiler calls stop_machine
                         * so this acts like an synchronize_sched.
                         */
                        unregister_ftrace_profiler();
                }
        }
 out:
        mutex_unlock(&ftrace_profile_lock);

        *ppos += cnt;

        return cnt;
}

static ssize_t
ftrace_profile_read(struct file *filp, char __user *ubuf,
                     size_t cnt, loff_t *ppos)
{
        char buf[64];           /* big enough to hold a number */
        int r;

        r = sprintf(buf, "%u\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,
        .llseek         = default_llseek,
};

/* used to initialize the real stat files */
static struct tracer_stat function_stats __initdata = {
        .name           = "functions",
        .stat_start     = function_stat_start,
        .stat_next      = function_stat_next,
        .stat_cmp       = function_stat_cmp,
        .stat_headers   = function_stat_headers,
        .stat_show      = function_stat_show
};

static __init void ftrace_profile_tracefs(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 = tracefs_create_file("function_profile_enabled", 0644,
                                    d_tracer, NULL, &ftrace_profile_fops);
        if (!entry)
                pr_warn("Could not create tracefs 'function_profile_enabled' entry\n");
}

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

static struct pid * const ftrace_swapper_pid = &init_struct_pid;

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static int ftrace_graph_active;
#else
# define ftrace_graph_active 0
#endif

#ifdef CONFIG_DYNAMIC_FTRACE

static struct ftrace_ops *removed_ops;

/*
 * Set when doing a global update, like enabling all recs or disabling them.
 * It is not set when just updating a single ftrace_ops.
 */
static bool update_all_ops;

#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 list_head        free_list;
};

struct ftrace_func_entry {
        struct hlist_node hlist;
        unsigned long ip;
};

struct ftrace_hash {
        unsigned long           size_bits;
        struct hlist_head       *buckets;
        unsigned long           count;
        struct rcu_head         rcu;
};

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

static struct ftrace_ops global_ops = {
        .func                           = ftrace_stub,
        .local_hash.notrace_hash        = EMPTY_HASH,
        .local_hash.filter_hash         = EMPTY_HASH,
        INIT_OPS_HASH(global_ops)
        .flags                          = FTRACE_OPS_FL_RECURSION_SAFE |
                                          FTRACE_OPS_FL_INITIALIZED |
                                          FTRACE_OPS_FL_PID,
};

/*
 * This is used by __kernel_text_address() to return true if the
 * address is on a dynamically allocated trampoline that would
 * not return true for either core_kernel_text() or
 * is_module_text_address().
 */
bool is_ftrace_trampoline(unsigned long addr)
{
        struct ftrace_ops *op;
        bool ret = false;

        /*
         * Some of the ops may be dynamically allocated,
         * they are freed after a synchronize_sched().
         */
        preempt_disable_notrace();

        do_for_each_ftrace_op(op, ftrace_ops_list) {
                /*
                 * This is to check for dynamically allocated trampolines.
                 * Trampolines that are in kernel text will have
                 * core_kernel_text() return true.
                 */
                if (op->trampoline && op->trampoline_size)
                        if (addr >= op->trampoline &&
                            addr < op->trampoline + op->trampoline_size) {
                                ret = true;
                                goto out;
                        }
        } while_for_each_ftrace_op(op);

 out:
        preempt_enable_notrace();

        return ret;
}

struct ftrace_page {
        struct ftrace_page      *next;
        struct dyn_ftrace       *records;
        int                     index;
        int                     size;
};

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

/* estimate from running different kernels */
#define NR_TO_INIT              10000

static struct ftrace_page       *ftrace_pages_start;
static struct ftrace_page       *ftrace_pages;

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

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

        if (ftrace_hash_empty(hash))
                return NULL;

        if (hash->size_bits > 0)
                key = hash_long(ip, hash->size_bits);
        else
                key = 0;

        hhd = &hash->buckets[key];

        hlist_for_each_entry_rcu_notrace(entry, hhd, hlist) {
                if (entry->ip == ip)
                        return entry;
        }
        return NULL;
}

static void __add_hash_entry(struct ftrace_hash *hash,
                             struct ftrace_func_entry *entry)
{
        struct hlist_head *hhd;
        unsigned long key;

        if (hash->size_bits)
                key = hash_long(entry->ip, hash->size_bits);
        else
                key = 0;

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

static int add_hash_entry(struct ftrace_hash *hash, unsigned long ip)
{
        struct ftrace_func_entry *entry;

        entry = kmalloc(sizeof(*entry), GFP_KERNEL);
        if (!entry)
                return -ENOMEM;

        entry->ip = ip;
        __add_hash_entry(hash, entry);

        return 0;
}

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

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

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

        if (!hash->count)
                return;

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

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

static void __free_ftrace_hash_rcu(struct rcu_head *rcu)
{
        struct ftrace_hash *hash;

        hash = container_of(rcu, struct ftrace_hash, rcu);
        free_ftrace_hash(hash);
}

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

void ftrace_free_filter(struct ftrace_ops *ops)
{
        ftrace_ops_init(ops);
        free_ftrace_hash(ops->func_hash->filter_hash);
        free_ftrace_hash(ops->func_hash->notrace_hash);
}

static struct ftrace_hash *alloc_ftrace_hash(int size_bits)
{
        struct ftrace_hash *hash;
        int size;

        hash = kzalloc(sizeof(*hash), GFP_KERNEL);
        if (!hash)
                return NULL;

        size = 1 << size_bits;
        hash->buckets = kcalloc(size, sizeof(*hash->buckets), GFP_KERNEL);

        if (!hash->buckets) {
                kfree(hash);
                return NULL;
        }

        hash->size_bits = size_bits;

        return hash;
}

static struct ftrace_hash *
alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash)
{
        struct ftrace_func_entry *entry;
        struct ftrace_hash *new_hash;
        int size;
        int ret;
        int i;

        new_hash = alloc_ftrace_hash(size_bits);
        if (!new_hash)
                return NULL;

        /* Empty hash? */
        if (ftrace_hash_empty(hash))
                return new_hash;

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

        FTRACE_WARN_ON(new_hash->count != hash->count);

        return new_hash;

 free_hash:
        free_ftrace_hash(new_hash);
        return NULL;
}

static void
ftrace_hash_rec_disable_modify(struct ftrace_ops *ops, int filter_hash);
static void
ftrace_hash_rec_enable_modify(struct ftrace_ops *ops, int filter_hash);

static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops,
                                       struct ftrace_hash *new_hash);

static int
ftrace_hash_move(struct ftrace_ops *ops, int enable,
                 struct ftrace_hash **dst, struct ftrace_hash *src)
{
        struct ftrace_func_entry *entry;
        struct hlist_node *tn;
        struct hlist_head *hhd;
        struct ftrace_hash *new_hash;
        int size = src->count;
        int bits = 0;
        int ret;
        int i;

        /* Reject setting notrace hash on IPMODIFY ftrace_ops */
        if (ops->flags & FTRACE_OPS_FL_IPMODIFY && !enable)
                return -EINVAL;

        /*
         * If the new source is empty, just free dst and assign it
         * the empty_hash.
         */
        if (!src->count) {
                new_hash = EMPTY_HASH;
                goto update;
        }

        /*
         * Make the hash size about 1/2 the # found
         */
        for (size /= 2; size; size >>= 1)
                bits++;

        /* Don't allocate too much */
        if (bits > FTRACE_HASH_MAX_BITS)
                bits = FTRACE_HASH_MAX_BITS;

        new_hash = alloc_ftrace_hash(bits);
        if (!new_hash)
                return -ENOMEM;

        size = 1 << src->size_bits;
        for (i = 0; i < size; i++) {
                hhd = &src->buckets[i];
                hlist_for_each_entry_safe(entry, tn, hhd, hlist) {
                        remove_hash_entry(src, entry);
                        __add_hash_entry(new_hash, entry);
                }
        }

update:
        /* Make sure this can be applied if it is IPMODIFY ftrace_ops */
        if (enable) {
                /* IPMODIFY should be updated only when filter_hash updating */
                ret = ftrace_hash_ipmodify_update(ops, new_hash);
                if (ret < 0) {
                        free_ftrace_hash(new_hash);
                        return ret;
                }
        }

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

        rcu_assign_pointer(*dst, new_hash);

        ftrace_hash_rec_enable_modify(ops, enable);

        return 0;
}

static bool hash_contains_ip(unsigned long ip,
                             struct ftrace_ops_hash *hash)
{
        /*
         * The function record is a match if it exists in the filter
         * hash and not in the notrace hash. Note, an emty hash is
         * considered a match for the filter hash, but an empty
         * notrace hash is considered not in the notrace hash.
         */
        return (ftrace_hash_empty(hash->filter_hash) ||
                ftrace_lookup_ip(hash->filter_hash, ip)) &&
                (ftrace_hash_empty(hash->notrace_hash) ||
                 !ftrace_lookup_ip(hash->notrace_hash, ip));
}

/*
 * Test the hashes for this ops to see if we want to call
 * the ops->func or not.
 *
 * It's a match if the ip is in the ops->filter_hash or
 * the filter_hash does not exist or is empty,
 *  AND
 * the ip is not in the ops->notrace_hash.
 *
 * This needs to be called with preemption disabled as
 * the hashes are freed with call_rcu_sched().
 */
static int
ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
{
        struct ftrace_ops_hash hash;
        int ret;

#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
        /*
         * There's a small race when adding ops that the ftrace handler
         * that wants regs, may be called without them. We can not
         * allow that handler to be called if regs is NULL.
         */
        if (regs == NULL && (ops->flags & FTRACE_OPS_FL_SAVE_REGS))
                return 0;
#endif

        hash.filter_hash = rcu_dereference_raw_notrace(ops->func_hash->filter_hash);
        hash.notrace_hash = rcu_dereference_raw_notrace(ops->func_hash->notrace_hash);

        if (hash_contains_ip(ip, &hash))
                ret = 1;
        else
                ret = 0;

        return ret;
}

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

#define while_for_each_ftrace_rec()             \
                }                               \
        }


static int ftrace_cmp_recs(const void *a, const void *b)
{
        const struct dyn_ftrace *key = a;
        const struct dyn_ftrace *rec = b;

        if (key->flags < rec->ip)
                return -1;
        if (key->ip >= rec->ip + MCOUNT_INSN_SIZE)
                return 1;
        return 0;
}

static unsigned long ftrace_location_range(unsigned long start, unsigned long end)
{
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;
        struct dyn_ftrace key;

        key.ip = start;
        key.flags = end;        /* overload flags, as it is unsigned long */

        for (pg = ftrace_pages_start; pg; pg = pg->next) {
                if (end < pg->records[0].ip ||
                    start >= (pg->records[pg->index - 1].ip + MCOUNT_INSN_SIZE))
                        continue;
                rec = bsearch(&key, pg->records, pg->index,
                              sizeof(struct dyn_ftrace),
                              ftrace_cmp_recs);
                if (rec)
                        return rec->ip;
        }

        return 0;
}

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

/**
 * ftrace_text_reserved - return true if range contains an ftrace location
 * @start: start of range to search
 * @end: end of range to search (inclusive). @end points to the last byte to check.
 *
 * Returns 1 if @start and @end contains a ftrace location.
 * That is, the instruction that is either a NOP or call to
 * the function tracer. It checks the ftrace internal tables to
 * determine if the address belongs or not.
 */
int ftrace_text_reserved(const void *start, const void *end)
{
        unsigned long ret;

        ret = ftrace_location_range((unsigned long)start,
                                    (unsigned long)end);

        return (int)!!ret;
}

/* Test if ops registered to this rec needs regs */
static bool test_rec_ops_needs_regs(struct dyn_ftrace *rec)
{
        struct ftrace_ops *ops;
        bool keep_regs = false;

        for (ops = ftrace_ops_list;
             ops != &ftrace_list_end; ops = ops->next) {
                /* pass rec in as regs to have non-NULL val */
                if (ftrace_ops_test(ops, rec->ip, rec)) {
                        if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
                                keep_regs = true;
                                break;
                        }
                }
        }

        return  keep_regs;
}

static void __ftrace_hash_rec_update(struct ftrace_ops *ops,
                                     int filter_hash,
                                     bool inc)
{
        struct ftrace_hash *hash;
        struct ftrace_hash *other_hash;
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;
        int count = 0;
        int all = 0;

        /* Only update if the ops has been registered */
        if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
                return;

        /*
         * In the filter_hash case:
         *   If the count is zero, we update all records.
         *   Otherwise we just update the items in the hash.
         *
         * In the notrace_hash case:
         *   We enable the update in the hash.
         *   As disabling notrace means enabling the tracing,
         *   and enabling notrace means disabling, the inc variable
         *   gets inversed.
         */
        if (filter_hash) {
                hash = ops->func_hash->filter_hash;
                other_hash = ops->func_hash->notrace_hash;
                if (ftrace_hash_empty(hash))
                        all = 1;
        } else {
                inc = !inc;
                hash = ops->func_hash->notrace_hash;
                other_hash = ops->func_hash->filter_hash;
                /*
                 * If the notrace hash has no items,
                 * then there's nothing to do.
                 */
                if (ftrace_hash_empty(hash))
                        return;
        }

        do_for_each_ftrace_rec(pg, rec) {
                int in_other_hash = 0;
                int in_hash = 0;
                int match = 0;

                if (rec->flags & FTRACE_FL_DISABLED)
                        continue;

                if (all) {
                        /*
                         * Only the filter_hash affects all records.
                         * Update if the record is not in the notrace hash.
                         */
                        if (!other_hash || !ftrace_lookup_ip(other_hash, rec->ip))
                                match = 1;
                } else {
                        in_hash = !!ftrace_lookup_ip(hash, rec->ip);
                        in_other_hash = !!ftrace_lookup_ip(other_hash, rec->ip);

                        /*
                         * If filter_hash is set, we want to match all functions
                         * that are in the hash but not in the other hash.
                         *
                         * If filter_hash is not set, then we are decrementing.
                         * That means we match anything that is in the hash
                         * and also in the other_hash. That is, we need to turn
                         * off functions in the other hash because they are disabled
                         * by this hash.
                         */
                        if (filter_hash && in_hash && !in_other_hash)
                                match = 1;
                        else if (!filter_hash && in_hash &&
                                 (in_other_hash || ftrace_hash_empty(other_hash)))
                                match = 1;
                }
                if (!match)
                        continue;

                if (inc) {
                        rec->flags++;
                        if (FTRACE_WARN_ON(ftrace_rec_count(rec) == FTRACE_REF_MAX))
                                return;

                        /*
                         * If there's only a single callback registered to a
                         * function, and the ops has a trampoline registered
                         * for it, then we can call it directly.
                         */
                        if (ftrace_rec_count(rec) == 1 && ops->trampoline)
                                rec->flags |= FTRACE_FL_TRAMP;
                        else
                                /*
                                 * If we are adding another function callback
                                 * to this function, and the previous had a
                                 * custom trampoline in use, then we need to go
                                 * back to the default trampoline.
                                 */
                                rec->flags &= ~FTRACE_FL_TRAMP;

                        /*
                         * If any ops wants regs saved for this function
                         * then all ops will get saved regs.
                         */
                        if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
                                rec->flags |= FTRACE_FL_REGS;
                } else {
                        if (FTRACE_WARN_ON(ftrace_rec_count(rec) == 0))
                                return;
                        rec->flags--;

                        /*
                         * If the rec had REGS enabled and the ops that is
                         * being removed had REGS set, then see if there is
                         * still any ops for this record that wants regs.
                         * If not, we can stop recording them.
                         */
                        if (ftrace_rec_count(rec) > 0 &&
                            rec->flags & FTRACE_FL_REGS &&
                            ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
                                if (!test_rec_ops_needs_regs(rec))
                                        rec->flags &= ~FTRACE_FL_REGS;
                        }

                        /*
                         * If the rec had TRAMP enabled, then it needs to
                         * be cleared. As TRAMP can only be enabled iff
                         * there is only a single ops attached to it.
                         * In otherwords, always disable it on decrementing.
                         * In the future, we may set it if rec count is
                         * decremented to one, and the ops that is left
                         * has a trampoline.
                         */
                        rec->flags &= ~FTRACE_FL_TRAMP;

                        /*
                         * flags will be cleared in ftrace_check_record()
                         * if rec count is zero.
                         */
                }
                count++;
                /* Shortcut, if we handled all records, we are done. */
                if (!all && count == hash->count)
                        return;
        } while_for_each_ftrace_rec();
}

static void ftrace_hash_rec_disable(struct ftrace_ops *ops,
                                    int filter_hash)
{
        __ftrace_hash_rec_update(ops, filter_hash, 0);
}

static void ftrace_hash_rec_enable(struct ftrace_ops *ops,
                                   int filter_hash)
{
        __ftrace_hash_rec_update(ops, filter_hash, 1);
}

static void ftrace_hash_rec_update_modify(struct ftrace_ops *ops,
                                          int filter_hash, int inc)
{
        struct ftrace_ops *op;

        __ftrace_hash_rec_update(ops, filter_hash, inc);

        if (ops->func_hash != &global_ops.local_hash)
                return;

        /*
         * If the ops shares the global_ops hash, then we need to update
         * all ops that are enabled and use this hash.
         */
        do_for_each_ftrace_op(op, ftrace_ops_list) {
                /* Already done */
                if (op == ops)
                        continue;
                if (op->func_hash == &global_ops.local_hash)
                        __ftrace_hash_rec_update(op, filter_hash, inc);
        } while_for_each_ftrace_op(op);
}

static void ftrace_hash_rec_disable_modify(struct ftrace_ops *ops,
                                           int filter_hash)
{
        ftrace_hash_rec_update_modify(ops, filter_hash, 0);
}

static void ftrace_hash_rec_enable_modify(struct ftrace_ops *ops,
                                          int filter_hash)
{
        ftrace_hash_rec_update_modify(ops, filter_hash, 1);
}

/*
 * Try to update IPMODIFY flag on each ftrace_rec. Return 0 if it is OK
 * or no-needed to update, -EBUSY if it detects a conflict of the flag
 * on a ftrace_rec, and -EINVAL if the new_hash tries to trace all recs.
 * Note that old_hash and new_hash has below meanings
 *  - If the hash is NULL, it hits all recs (if IPMODIFY is set, this is rejected)
 *  - If the hash is EMPTY_HASH, it hits nothing
 *  - Anything else hits the recs which match the hash entries.
 */
static int __ftrace_hash_update_ipmodify(struct ftrace_ops *ops,
                                         struct ftrace_hash *old_hash,
                                         struct ftrace_hash *new_hash)
{
        struct ftrace_page *pg;
        struct dyn_ftrace *rec, *end = NULL;
        int in_old, in_new;

        /* Only update if the ops has been registered */
        if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
                return 0;

        if (!(ops->flags & FTRACE_OPS_FL_IPMODIFY))
                return 0;

        /*
         * Since the IPMODIFY is a very address sensitive action, we do not
         * allow ftrace_ops to set all functions to new hash.
         */
        if (!new_hash || !old_hash)
                return -EINVAL;

        /* Update rec->flags */
        do_for_each_ftrace_rec(pg, rec) {
                /* We need to update only differences of filter_hash */
                in_old = !!ftrace_lookup_ip(old_hash, rec->ip);
                in_new = !!ftrace_lookup_ip(new_hash, rec->ip);
                if (in_old == in_new)
                        continue;

                if (in_new) {
                        /* New entries must ensure no others are using it */
                        if (rec->flags & FTRACE_FL_IPMODIFY)
                                goto rollback;
                        rec->flags |= FTRACE_FL_IPMODIFY;
                } else /* Removed entry */
                        rec->flags &= ~FTRACE_FL_IPMODIFY;
        } while_for_each_ftrace_rec();

        return 0;

rollback:
        end = rec;

        /* Roll back what we did above */
        do_for_each_ftrace_rec(pg, rec) {
                if (rec == end)
                        goto err_out;

                in_old = !!ftrace_lookup_ip(old_hash, rec->ip);
                in_new = !!ftrace_lookup_ip(new_hash, rec->ip);
                if (in_old == in_new)
                        continue;

                if (in_new)
                        rec->flags &= ~FTRACE_FL_IPMODIFY;
                else
                        rec->flags |= FTRACE_FL_IPMODIFY;
        } while_for_each_ftrace_rec();

err_out:
        return -EBUSY;
}

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

        if (ftrace_hash_empty(hash))
                hash = NULL;

        return __ftrace_hash_update_ipmodify(ops, EMPTY_HASH, hash);
}

/* Disabling always succeeds */
static void ftrace_hash_ipmodify_disable(struct ftrace_ops *ops)
{
        struct ftrace_hash *hash = ops->func_hash->filter_hash;

        if (ftrace_hash_empty(hash))
                hash = NULL;

        __ftrace_hash_update_ipmodify(ops, hash, EMPTY_HASH);
}

static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops,
                                       struct ftrace_hash *new_hash)
{
        struct ftrace_hash *old_hash = ops->func_hash->filter_hash;

        if (ftrace_hash_empty(old_hash))
                old_hash = NULL;

        if (ftrace_hash_empty(new_hash))
                new_hash = NULL;

        return __ftrace_hash_update_ipmodify(ops, old_hash, new_hash);
}

static void print_ip_ins(const char *fmt, const 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 struct ftrace_ops *
ftrace_find_tramp_ops_any(struct dyn_ftrace *rec);
static struct ftrace_ops *
ftrace_find_tramp_ops_next(struct dyn_ftrace *rec, struct ftrace_ops *ops);

enum ftrace_bug_type ftrace_bug_type;
const void *ftrace_expected;

static void print_bug_type(void)
{
        switch (ftrace_bug_type) {
        case FTRACE_BUG_UNKNOWN:
                break;
        case FTRACE_BUG_INIT:
                pr_info("Initializing ftrace call sites\n");
                break;
        case FTRACE_BUG_NOP:
                pr_info("Setting ftrace call site to NOP\n");
                break;
        case FTRACE_BUG_CALL:
                pr_info("Setting ftrace call site to call ftrace function\n");
                break;
        case FTRACE_BUG_UPDATE:
                pr_info("Updating ftrace call site to call a different ftrace function\n");
                break;
        }
}

/**
 * ftrace_bug - report and shutdown function tracer
 * @failed: The failed type (EFAULT, EINVAL, EPERM)
 * @rec: The record that failed
 *
 * The arch code that enables or disables the function tracing
 * can call ftrace_bug() when it has detected a problem in
 * modifying the code. @failed should be one of either:
 * EFAULT - if the problem happens on reading the @ip address
 * EINVAL - if what is read at @ip is not what was expected
 * EPERM - if the problem happens on writting to the @ip address
 */
void ftrace_bug(int failed, struct dyn_ftrace *rec)
{
        unsigned long ip = rec ? rec->ip : 0;

        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);
                pr_cont("\n");
                if (ftrace_expected) {
                        print_ip_ins(" expected: ", ftrace_expected);
                        pr_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);
        }
        print_bug_type();
        if (rec) {
                struct ftrace_ops *ops = NULL;

                pr_info("ftrace record flags: %lx\n", rec->flags);
                pr_cont(" (%ld)%s", ftrace_rec_count(rec),
                        rec->flags & FTRACE_FL_REGS ? " R" : "  ");
                if (rec->flags & FTRACE_FL_TRAMP_EN) {
                        ops = ftrace_find_tramp_ops_any(rec);
                        if (ops) {
                                do {
                                        pr_cont("\ttramp: %pS (%pS)",
                                                (void *)ops->trampoline,
                                                (void *)ops->func);
                                        ops = ftrace_find_tramp_ops_next(rec, ops);
                                } while (ops);
                        } else
                                pr_cont("\ttramp: ERROR!");

                }
                ip = ftrace_get_addr_curr(rec);
                pr_cont("\n expected tramp: %lx\n", ip);
        }
}

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

        ftrace_bug_type = FTRACE_BUG_UNKNOWN;

        if (rec->flags & FTRACE_FL_DISABLED)
                return FTRACE_UPDATE_IGNORE;

        /*
         * If we are updating calls:
         *
         *   If the record has a ref count, then we need to enable it
         *   because someone is using it.
         *
         *   Otherwise we make sure its disabled.
         *
         * If we are disabling calls, then disable all records that
         * are enabled.
         */
        if (enable && ftrace_rec_count(rec))
                flag = FTRACE_FL_ENABLED;

        /*
         * If enabling and the REGS flag does not match the REGS_EN, or
         * the TRAMP flag doesn't match the TRAMP_EN, then do not ignore
         * this record. Set flags to fail the compare against ENABLED.
         */
        if (flag) {
                if (!(rec->flags & FTRACE_FL_REGS) != 
                    !(rec->flags & FTRACE_FL_REGS_EN))
                        flag |= FTRACE_FL_REGS;

                if (!(rec->flags & FTRACE_FL_TRAMP) != 
                    !(rec->flags & FTRACE_FL_TRAMP_EN))
                        flag |= FTRACE_FL_TRAMP;
        }

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

        if (flag) {
                /* Save off if rec is being enabled (for return value) */
                flag ^= rec->flags & FTRACE_FL_ENABLED;

                if (update) {
                        rec->flags |= FTRACE_FL_ENABLED;
                        if (flag & FTRACE_FL_REGS) {
                                if (rec->flags & FTRACE_FL_REGS)
                                        rec->flags |= FTRACE_FL_REGS_EN;
                                else
                                        rec->flags &= ~FTRACE_FL_REGS_EN;
                        }
                        if (flag & FTRACE_FL_TRAMP) {
                                if (rec->flags & FTRACE_FL_TRAMP)
                                        rec->flags |= FTRACE_FL_TRAMP_EN;
                                else
                                        rec->flags &= ~FTRACE_FL_TRAMP_EN;
                        }
                }

                /*
                 * If this record is being updated from a nop, then
                 *   return UPDATE_MAKE_CALL.
                 * Otherwise,
                 *   return UPDATE_MODIFY_CALL to tell the caller to convert
                 *   from the save regs, to a non-save regs function or
                 *   vice versa, or from a trampoline call.
                 */
                if (flag & FTRACE_FL_ENABLED) {
                        ftrace_bug_type = FTRACE_BUG_CALL;
                        return FTRACE_UPDATE_MAKE_CALL;
                }

                ftrace_bug_type = FTRACE_BUG_UPDATE;
                return FTRACE_UPDATE_MODIFY_CALL;
        }

        if (update) {
                /* If there's no more users, clear all flags */
                if (!ftrace_rec_count(rec))
                        rec->flags = 0;
                else
                        /*
                         * Just disable the record, but keep the ops TRAMP
                         * and REGS states. The _EN flags must be disabled though.
                         */
                        rec->flags &= ~(FTRACE_FL_ENABLED | FTRACE_FL_TRAMP_EN |
                                        FTRACE_FL_REGS_EN);
        }

        ftrace_bug_type = FTRACE_BUG_NOP;
        return FTRACE_UPDATE_MAKE_NOP;
}

/**
 * ftrace_update_record, set a record that now is tracing or not
 * @rec: the record to update
 * @enable: set to 1 if the record is tracing, zero to force disable
 *
 * The records that represent all functions that can be traced need
 * to be updated when tracing has been enabled.
 */
int ftrace_update_record(struct dyn_ftrace *rec, int enable)
{
        return ftrace_check_record(rec, enable, 1);
}

/**
 * ftrace_test_record, check if the record has been enabled or not
 * @rec: the record to test
 * @enable: set to 1 to check if enabled, 0 if it is disabled
 *
 * The arch code may need to test if a record is already set to
 * tracing to determine how to modify the function code that it
 * represents.
 */
int ftrace_test_record(struct dyn_ftrace *rec, int enable)
{
        return ftrace_check_record(rec, enable, 0);
}

static struct ftrace_ops *
ftrace_find_tramp_ops_any(struct dyn_ftrace *rec)
{
        struct ftrace_ops *op;
        unsigned long ip = rec->ip;

        do_for_each_ftrace_op(op, ftrace_ops_list) {

                if (!op->trampoline)
                        continue;

                if (hash_contains_ip(ip, op->func_hash))
                        return op;
        } while_for_each_ftrace_op(op);

        return NULL;
}

static struct ftrace_ops *
ftrace_find_tramp_ops_next(struct dyn_ftrace *rec,
                           struct ftrace_ops *op)
{
        unsigned long ip = rec->ip;

        while_for_each_ftrace_op(op) {

                if (!op->trampoline)
                        continue;

                if (hash_contains_ip(ip, op->func_hash))
                        return op;
        } 

        return NULL;
}

static struct ftrace_ops *
ftrace_find_tramp_ops_curr(struct dyn_ftrace *rec)
{
        struct ftrace_ops *op;
        unsigned long ip = rec->ip;

        /*
         * Need to check removed ops first.
         * If they are being removed, and this rec has a tramp,
         * and this rec is in the ops list, then it would be the
         * one with the tramp.
         */
        if (removed_ops) {
                if (hash_contains_ip(ip, &removed_ops->old_hash))
                        return removed_ops;
        }

        /*
         * Need to find the current trampoline for a rec.
         * Now, a trampoline is only attached to a rec if there
         * was a single 'ops' attached to it. But this can be called
         * when we are adding another op to the rec or removing the
         * current one. Thus, if the op is being added, we can
         * ignore it because it hasn't attached itself to the rec
         * yet.
         *
         * If an ops is being modified (hooking to different functions)
         * then we don't care about the new functions that are being
         * added, just the old ones (that are probably being removed).
         *
         * If we are adding an ops to a function that already is using
         * a trampoline, it needs to be removed (trampolines are only
         * for single ops connected), then an ops that is not being
         * modified also needs to be checked.
         */
        do_for_each_ftrace_op(op, ftrace_ops_list) {

                if (!op->trampoline)
                        continue;

                /*
                 * If the ops is being added, it hasn't gotten to
                 * the point to be removed from this tree yet.
                 */
                if (op->flags & FTRACE_OPS_FL_ADDING)
                        continue;


                /*
                 * If the ops is being modified and is in the old
                 * hash, then it is probably being removed from this
                 * function.
                 */
                if ((op->flags & FTRACE_OPS_FL_MODIFYING) &&
                    hash_contains_ip(ip, &op->old_hash))
                        return op;
                /*
                 * If the ops is not being added or modified, and it's
                 * in its normal filter hash, then this must be the one
                 * we want!
                 */
                if (!(op->flags & FTRACE_OPS_FL_MODIFYING) &&
                    hash_contains_ip(ip, op->func_hash))
                        return op;

        } while_for_each_ftrace_op(op);

        return NULL;
}

static struct ftrace_ops *
ftrace_find_tramp_ops_new(struct dyn_ftrace *rec)
{
        struct ftrace_ops *op;
        unsigned long ip = rec->ip;

        do_for_each_ftrace_op(op, ftrace_ops_list) {
                /* pass rec in as regs to have non-NULL val */
                if (hash_contains_ip(ip, op->func_hash))
                        return op;
        } while_for_each_ftrace_op(op);

        return NULL;
}

/**
 * ftrace_get_addr_new - Get the call address to set to
 * @rec:  The ftrace record descriptor
 *
 * If the record has the FTRACE_FL_REGS set, that means that it
 * wants to convert to a callback that saves all regs. If FTRACE_FL_REGS
 * is not not set, then it wants to convert to the normal callback.
 *
 * Returns the address of the trampoline to set to
 */
unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec)
{
        struct ftrace_ops *ops;

        /* Trampolines take precedence over regs */
        if (rec->flags & FTRACE_FL_TRAMP) {
                ops = ftrace_find_tramp_ops_new(rec);
                if (FTRACE_WARN_ON(!ops || !ops->trampoline)) {
                        pr_warn("Bad trampoline accounting at: %p (%pS) (%lx)\n",
                                (void *)rec->ip, (void *)rec->ip, rec->flags);
                        /* Ftrace is shutting down, return anything */
                        return (unsigned long)FTRACE_ADDR;
                }
                return ops->trampoline;
        }

        if (rec->flags & FTRACE_FL_REGS)
                return (unsigned long)FTRACE_REGS_ADDR;
        else
                return (unsigned long)FTRACE_ADDR;
}

/**
 * ftrace_get_addr_curr - Get the call address that is already there
 * @rec:  The ftrace record descriptor
 *
 * The FTRACE_FL_REGS_EN is set when the record already points to
 * a function that saves all the regs. Basically the '_EN' version
 * represents the current state of the function.
 *
 * Returns the address of the trampoline that is currently being called
 */
unsigned long ftrace_get_addr_curr(struct dyn_ftrace *rec)
{
        struct ftrace_ops *ops;

        /* Trampolines take precedence over regs */
        if (rec->flags & FTRACE_FL_TRAMP_EN) {
                ops = ftrace_find_tramp_ops_curr(rec);
                if (FTRACE_WARN_ON(!ops)) {
                        pr_warn("Bad trampoline accounting at: %p (%pS)\n",
                                (void *)rec->ip, (void *)rec->ip);
                        /* Ftrace is shutting down, return anything */
                        return (unsigned long)FTRACE_ADDR;
                }
                return ops->trampoline;
        }

        if (rec->flags & FTRACE_FL_REGS_EN)
                return (unsigned long)FTRACE_REGS_ADDR;
        else
                return (unsigned long)FTRACE_ADDR;
}

static int
__ftrace_replace_code(struct dyn_ftrace *rec, int enable)
{
        unsigned long ftrace_old_addr;
        unsigned long ftrace_addr;
        int ret;

        ftrace_addr = ftrace_get_addr_new(rec);

        /* This needs to be done before we call ftrace_update_record */
        ftrace_old_addr = ftrace_get_addr_curr(rec);

        ret = ftrace_update_record(rec, enable);

        ftrace_bug_type = FTRACE_BUG_UNKNOWN;

        switch (ret) {
        case FTRACE_UPDATE_IGNORE:
                return 0;

        case FTRACE_UPDATE_MAKE_CALL:
                ftrace_bug_type = FTRACE_BUG_CALL;
                return ftrace_make_call(rec, ftrace_addr);

        case FTRACE_UPDATE_MAKE_NOP:
                ftrace_bug_type = FTRACE_BUG_NOP;
                return ftrace_make_nop(NULL, rec, ftrace_old_addr);

        case FTRACE_UPDATE_MODIFY_CALL:
                ftrace_bug_type = FTRACE_BUG_UPDATE;
                return ftrace_modify_call(rec, ftrace_old_addr, ftrace_addr);
        }

        return -1; /* unknow ftrace bug */
}

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

        if (unlikely(ftrace_disabled))
                return;

        do_for_each_ftrace_rec(pg, rec) {
                failed = __ftrace_replace_code(rec, enable);
                if (failed) {
                        ftrace_bug(failed, rec);
                        /* Stop processing */
                        return;
                }
        } while_for_each_ftrace_rec();
}

struct ftrace_rec_iter {
        struct ftrace_page      *pg;
        int                     index;
};

/**
 * ftrace_rec_iter_start, start up iterating over traced functions
 *
 * Returns an iterator handle that is used to iterate over all
 * the records that represent address locations where functions
 * are traced.
 *
 * May return NULL if no records are available.
 */
struct ftrace_rec_iter *ftrace_rec_iter_start(void)
{
        /*
         * We only use a single iterator.
         * Protected by the ftrace_lock mutex.
         */
        static struct ftrace_rec_iter ftrace_rec_iter;
        struct ftrace_rec_iter *iter = &ftrace_rec_iter;

        iter->pg = ftrace_pages_start;
        iter->index = 0;

        /* Could have empty pages */
        while (iter->pg && !iter->pg->index)
                iter->pg = iter->pg->next;

        if (!iter->pg)
                return NULL;

        return iter;
}

/**
 * ftrace_rec_iter_next, get the next record to process.
 * @iter: The handle to the iterator.
 *
 * Returns the next iterator after the given iterator @iter.
 */
struct ftrace_rec_iter *ftrace_rec_iter_next(struct ftrace_rec_iter *iter)
{
        iter->index++;

        if (iter->index >= iter->pg->index) {
                iter->pg = iter->pg->next;
                iter->index = 0;

                /* Could have empty pages */
                while (iter->pg && !iter->pg->index)
                        iter->pg = iter->pg->next;
        }

        if (!iter->pg)
                return NULL;

        return iter;
}

/**
 * ftrace_rec_iter_record, get the record at the iterator location
 * @iter: The current iterator location
 *
 * Returns the record that the current @iter is at.
 */
struct dyn_ftrace *ftrace_rec_iter_record(struct ftrace_rec_iter *iter)
{
        return &iter->pg->records[iter->index];
}

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

        if (unlikely(ftrace_disabled))
                return 0;

        ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
        if (ret) {
                ftrace_bug_type = FTRACE_BUG_INIT;
                ftrace_bug(ret, rec);
                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;
}

void ftrace_modify_all_code(int command)
{
        int update = command & FTRACE_UPDATE_TRACE_FUNC;
        int err = 0;

        /*
         * If the ftrace_caller calls a ftrace_ops func directly,
         * we need to make sure that it only traces functions it
         * expects to trace. When doing the switch of functions,
         * we need to update to the ftrace_ops_list_func first
         * before the transition between old and new calls are set,
         * as the ftrace_ops_list_func will check the ops hashes
         * to make sure the ops are having the right functions
         * traced.
         */
        if (update) {
                err = ftrace_update_ftrace_func(ftrace_ops_list_func);
                if (FTRACE_WARN_ON(err))
                        return;
        }

        if (command & FTRACE_UPDATE_CALLS)
                ftrace_replace_code(1);
        else if (command & FTRACE_DISABLE_CALLS)
                ftrace_replace_code(0);

        if (update && ftrace_trace_function != ftrace_ops_list_func) {
                function_trace_op = set_function_trace_op;
                smp_wmb();
                /* If irqs are disabled, we are in stop machine */
                if (!irqs_disabled())
                        smp_call_function(ftrace_sync_ipi, NULL, 1);
                err = ftrace_update_ftrace_func(ftrace_trace_function);
                if (FTRACE_WARN_ON(err))
                        return;
        }

        if (command & FTRACE_START_FUNC_RET)
                err = ftrace_enable_ftrace_graph_caller();
        else if (command & FTRACE_STOP_FUNC_RET)
                err = ftrace_disable_ftrace_graph_caller();
        FTRACE_WARN_ON(err);
}

static int __ftrace_modify_code(void *data)
{
        int *command = data;

        ftrace_modify_all_code(*command);

        return 0;
}

/**
 * ftrace_run_stop_machine, go back to the stop machine method
 * @command: The command to tell ftrace what to do
 *
 * If an arch needs to fall back to the stop machine method, the
 * it can call this function.
 */
void ftrace_run_stop_machine(int command)
{
        stop_machine(__ftrace_modify_code, &command, NULL);
}

/**
 * arch_ftrace_update_code, modify the code to trace or not trace
 * @command: The command that needs to be done
 *
 * Archs can override this function if it does not need to
 * run stop_machine() to modify code.
 */
void __weak arch_ftrace_update_code(int command)
{
        ftrace_run_stop_machine(command);
}

static void ftrace_run_update_code(int command)
{
        int ret;

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

        /*
         * By default we use stop_machine() to modify the code.
         * But archs can do what ever they want as long as it
         * is safe. The stop_machine() is the safest, but also
         * produces the most overhead.
         */
        arch_ftrace_update_code(command);

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

static void ftrace_run_modify_code(struct ftrace_ops *ops, int command,
                                   struct ftrace_ops_hash *old_hash)
{
        ops->flags |= FTRACE_OPS_FL_MODIFYING;
        ops->old_hash.filter_hash = old_hash->filter_hash;
        ops->old_hash.notrace_hash = old_hash->notrace_hash;
        ftrace_run_update_code(command);
        ops->old_hash.filter_hash = NULL;
        ops->old_hash.notrace_hash = NULL;
        ops->flags &= ~FTRACE_OPS_FL_MODIFYING;
}

static ftrace_func_t saved_ftrace_func;
static int ftrace_start_up;

void __weak arch_ftrace_trampoline_free(struct ftrace_ops *ops)
{
}

static void per_cpu_ops_free(struct ftrace_ops *ops)
{
        free_percpu(ops->disabled);
}

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_all(int command)
{
        update_all_ops = true;
        ftrace_startup_enable(command);
        update_all_ops = false;
}

static int ftrace_startup(struct ftrace_ops *ops, int command)
{
        int ret;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        ret = __register_ftrace_function(ops);
        if (ret)
                return ret;

        ftrace_start_up++;
        command |= FTRACE_UPDATE_CALLS;

        /*
         * Note that ftrace probes uses this to start up
         * and modify functions it will probe. But we still
         * set the ADDING flag for modification, as probes
         * do not have trampolines. If they add them in the
         * future, then the probes will need to distinguish
         * between adding and updating probes.
         */
        ops->flags |= FTRACE_OPS_FL_ENABLED | FTRACE_OPS_FL_ADDING;

        ret = ftrace_hash_ipmodify_enable(ops);
        if (ret < 0) {
                /* Rollback registration process */
                __unregister_ftrace_function(ops);
                ftrace_start_up--;
                ops->flags &= ~FTRACE_OPS_FL_ENABLED;
                return ret;
        }

        ftrace_hash_rec_enable(ops, 1);

        ftrace_startup_enable(command);

        ops->flags &= ~FTRACE_OPS_FL_ADDING;

        return 0;
}

static int ftrace_shutdown(struct ftrace_ops *ops, int command)
{
        int ret;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        ret = __unregister_ftrace_function(ops);
        if (ret)
                return ret;

        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);

        /* Disabling ipmodify never fails */
        ftrace_hash_ipmodify_disable(ops);
        ftrace_hash_rec_disable(ops, 1);

        ops->flags &= ~FTRACE_OPS_FL_ENABLED;

        command |= FTRACE_UPDATE_CALLS;

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

        if (!command || !ftrace_enabled) {
                /*
                 * If these are per_cpu ops, they still need their
                 * per_cpu field freed. Since, function tracing is
                 * not currently active, we can just free them
                 * without synchronizing all CPUs.
                 */
                if (ops->flags & FTRACE_OPS_FL_PER_CPU)
                        per_cpu_ops_free(ops);
                return 0;
        }

        /*
         * If the ops uses a trampoline, then it needs to be
         * tested first on update.
         */
        ops->flags |= FTRACE_OPS_FL_REMOVING;
        removed_ops = ops;

        /* The trampoline logic checks the old hashes */
        ops->old_hash.filter_hash = ops->func_hash->filter_hash;
        ops->old_hash.notrace_hash = ops->func_hash->notrace_hash;

        ftrace_run_update_code(command);

        /*
         * If there's no more ops registered with ftrace, run a
         * sanity check to make sure all rec flags are cleared.
         */
        if (ftrace_ops_list == &ftrace_list_end) {
                struct ftrace_page *pg;
                struct dyn_ftrace *rec;

                do_for_each_ftrace_rec(pg, rec) {
                        if (FTRACE_WARN_ON_ONCE(rec->flags))
                                pr_warn("  %pS flags:%lx\n",
                                        (void *)rec->ip, rec->flags);
                } while_for_each_ftrace_rec();
        }

        ops->old_hash.filter_hash = NULL;
        ops->old_hash.notrace_hash = NULL;

        removed_ops = NULL;
        ops->flags &= ~FTRACE_OPS_FL_REMOVING;

        /*
         * Dynamic ops may be freed, we must make sure that all
         * callers are done before leaving this function.
         * The same goes for freeing the per_cpu data of the per_cpu
         * ops.
         *
         * Again, normal synchronize_sched() is not good enough.
         * We need to do a hard force of sched synchronization.
         * This is because we use preempt_disable() to do RCU, but
         * the function tracers can be called where RCU is not watching
         * (like before user_exit()). We can not rely on the RCU
         * infrastructure to do the synchronization, thus we must do it
         * ourselves.
         */
        if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_PER_CPU)) {
                schedule_on_each_cpu(ftrace_sync);

                arch_ftrace_trampoline_free(ops);

                if (ops->flags & FTRACE_OPS_FL_PER_CPU)
                        per_cpu_ops_free(ops);
        }

        return 0;
}

static void ftrace_startup_sysctl(void)
{
        int command;

        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_UPDATE_CALLS;
                if (ftrace_graph_active)
                        command |= FTRACE_START_FUNC_RET;
                ftrace_startup_enable(command);
        }
}

static void ftrace_shutdown_sysctl(void)
{
        int command;

        if (unlikely(ftrace_disabled))
                return;

        /* ftrace_start_up is true if ftrace is running */
        if (ftrace_start_up) {
                command = FTRACE_DISABLE_CALLS;
                if (ftrace_graph_active)
                        command |= FTRACE_STOP_FUNC_RET;
                ftrace_run_update_code(command);
        }
}

static cycle_t          ftrace_update_time;
unsigned long           ftrace_update_tot_cnt;

static inline int ops_traces_mod(struct ftrace_ops *ops)
{
        /*
         * Filter_hash being empty will default to trace module.
         * But notrace hash requires a test of individual module functions.
         */
        return ftrace_hash_empty(ops->func_hash->filter_hash) &&
                ftrace_hash_empty(ops->func_hash->notrace_hash);
}

/*
 * Check if the current ops references the record.
 *
 * If the ops traces all functions, then it was already accounted for.
 * If the ops does not trace the current record function, skip it.
 * If the ops ignores the function via notrace filter, skip it.
 */
static inline bool
ops_references_rec(struct ftrace_ops *ops, struct dyn_ftrace *rec)
{
        /* If ops isn't enabled, ignore it */
        if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
                return 0;

        /* If ops traces all then it includes this function */
        if (ops_traces_mod(ops))
                return 1;

        /* The function must be in the filter */
        if (!ftrace_hash_empty(ops->func_hash->filter_hash) &&
            !ftrace_lookup_ip(ops->func_hash->filter_hash, rec->ip))
                return 0;

        /* If in notrace hash, we ignore it too */
        if (ftrace_lookup_ip(ops->func_hash->notrace_hash, rec->ip))
                return 0;

        return 1;
}

static int ftrace_update_code(struct module *mod, struct ftrace_page *new_pgs)
{
        struct ftrace_page *pg;
        struct dyn_ftrace *p;
        cycle_t start, stop;
        unsigned long update_cnt = 0;
        unsigned long rec_flags = 0;
        int i;

        start = ftrace_now(raw_smp_processor_id());

        /*
         * When a module is loaded, this function is called to convert
         * the calls to mcount in its text to nops, and also to create
         * an entry in the ftrace data. Now, if ftrace is activated
         * after this call, but before the module sets its text to
         * read-only, the modification of enabling ftrace can fail if
         * the read-only is done while ftrace is converting the calls.
         * To prevent this, the module's records are set as disabled
         * and will be enabled after the call to set the module's text
         * to read-only.
         */
        if (mod)
                rec_flags |= FTRACE_FL_DISABLED;

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

                for (i = 0; i < pg->index; i++) {

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

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

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

                        update_cnt++;
                }
        }

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

        return 0;
}

static int ftrace_allocate_records(struct ftrace_page *pg, int count)
{
        int order;
        int cnt;

        if (WARN_ON(!count))
                return -EINVAL;

        order = get_count_order(DIV_ROUND_UP(count, ENTRIES_PER_PAGE));

        /*
         * We want to fill as much as possible. No more than a page
         * may be empty.
         */
        while ((PAGE_SIZE << order) / ENTRY_SIZE >= count + ENTRIES_PER_PAGE)
                order--;

 again:
        pg->records = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, order);

        if (!pg->records) {
                /* if we can't allocate this size, try something smaller */
                if (!order)
                        return -ENOMEM;
                order >>= 1;
                goto again;
        }

        cnt = (PAGE_SIZE << order) / ENTRY_SIZE;
        pg->size = cnt;

        if (cnt > count)
                cnt = count;

        return cnt;
}

static struct ftrace_page *
ftrace_allocate_pages(unsigned long num_to_init)
{
        struct ftrace_page *start_pg;
        struct ftrace_page *pg;
        int order;
        int cnt;

        if (!num_to_init)
                return 0;

        start_pg = pg = kzalloc(sizeof(*pg), GFP_KERNEL);
        if (!pg)
                return NULL;

        /*
         * Try to allocate as much as possible in one continues
         * location that fills in all of the space. We want to
         * waste as little space as possible.
         */
        for (;;) {
                cnt = ftrace_allocate_records(pg, num_to_init);
                if (cnt < 0)
                        goto free_pages;

                num_to_init -= cnt;
                if (!num_to_init)
                        break;

                pg->next = kzalloc(sizeof(*pg), GFP_KERNEL);
                if (!pg->next)
                        goto free_pages;

                pg = pg->next;
        }

        return start_pg;

 free_pages:
        pg = start_pg;
        while (pg) {
                order = get_count_order(pg->size / ENTRIES_PER_PAGE);
                free_pages((unsigned long)pg->records, order);
                start_pg = pg->next;
                kfree(pg);
                pg = start_pg;
        }
        pr_info("ftrace: FAILED to allocate memory for functions\n");
        return NULL;
}

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

struct ftrace_iterator {
        loff_t                          pos;
        loff_t                          func_pos;
        struct ftrace_page              *pg;
        struct dyn_ftrace               *func;
        struct ftrace_func_probe        *probe;
        struct trace_parser             parser;
        struct ftrace_hash              *hash;
        struct ftrace_ops               *ops;
        int                             hidx;
        int                             idx;
        unsigned                        flags;
};

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

        (*pos)++;
        iter->pos = *pos;

        if (iter->probe)
                hnd = &iter->probe->node;
 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;
                }
        }

        if (WARN_ON_ONCE(!hnd))
                return NULL;

        iter->probe = hlist_entry(hnd, struct ftrace_func_probe, node);

        return iter;
}

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_DO_HASH))
                return NULL;

        if (iter->func_pos > *pos)
                return NULL;

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

        /* Only set this if we have an item */
        iter->flags |= FTRACE_ITER_HASH;

        return iter;
}

static int
t_hash_show(struct seq_file *m, struct ftrace_iterator *iter)
{
        struct ftrace_func_probe *rec;

        rec = iter->probe;
        if (WARN_ON_ONCE(!rec))
                return -EIO;

        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 ftrace_ops *ops = iter->ops;
        struct dyn_ftrace *rec = NULL;

        if (unlikely(ftrace_disabled))
                return NULL;

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

        (*pos)++;
        iter->pos = iter->func_pos = *pos;

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

 retry:
        if (iter->idx >= iter->pg->index) {
                if (iter->pg->next) {
                        iter->pg = iter->pg->next;
                        iter->idx = 0;
                        goto retry;
                }
        } else {
                rec = &iter->pg->records[iter->idx++];
                if (((iter->flags & FTRACE_ITER_FILTER) &&
                     !(ftrace_lookup_ip(ops->func_hash->filter_hash, rec->ip))) ||

                    ((iter->flags & FTRACE_ITER_NOTRACE) &&
                     !ftrace_lookup_ip(ops->func_hash->notrace_hash, rec->ip)) ||

                    ((iter->flags & FTRACE_ITER_ENABLED) &&
                     !(rec->flags & FTRACE_FL_ENABLED))) {

                        rec = NULL;
                        goto retry;
                }
        }

        if (!rec)
                return t_hash_start(m, pos);

        iter->func = rec;

        return iter;
}

static void reset_iter_read(struct ftrace_iterator *iter)
{
        iter->pos = 0;
        iter->func_pos = 0;
        iter->flags &= ~(FTRACE_ITER_PRINTALL | FTRACE_ITER_HASH);
}

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

        mutex_lock(&ftrace_lock);

        if (unlikely(ftrace_disabled))
                return NULL;

        /*
         * If an lseek was done, then reset and start from beginning.
         */
        if (*pos < iter->pos)
                reset_iter_read(iter);

        /*
         * 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_hash_empty(ops->func_hash->filter_hash)) ||
            (iter->flags & FTRACE_ITER_NOTRACE &&
             ftrace_hash_empty(ops->func_hash->notrace_hash))) {
                if (*pos > 0)
                        return t_hash_start(m, pos);
                iter->flags |= FTRACE_ITER_PRINTALL;
                /* reset in case of seek/pread */
                iter->flags &= ~FTRACE_ITER_HASH;
                return iter;
        }

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

        /*
         * Unfortunately, we need to restart at ftrace_pages_start
         * every time we let go of the ftrace_mutex. This is because
         * those pointers can change without the lock.
         */
        iter->pg = ftrace_pages_start;
        iter->idx = 0;
        for (l = 0; l <= *pos; ) {
                p = t_next(m, p, &l);
                if (!p)
                        break;
        }

        if (!p)
                return t_hash_start(m, pos);

        return iter;
}

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

void * __weak
arch_ftrace_trampoline_func(struct ftrace_ops *ops, struct dyn_ftrace *rec)
{
        return NULL;
}

static void add_trampoline_func(struct seq_file *m, struct ftrace_ops *ops,
                                struct dyn_ftrace *rec)
{
        void *ptr;

        ptr = arch_ftrace_trampoline_func(ops, rec);
        if (ptr)
                seq_printf(m, " ->%pS", ptr);
}

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

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

        if (iter->flags & FTRACE_ITER_PRINTALL) {
                if (iter->flags & FTRACE_ITER_NOTRACE)
                        seq_puts(m, "#### no functions disabled ####\n");
                else
                        seq_puts(m, "#### all functions enabled ####\n");
                return 0;
        }

        rec = iter->func;

        if (!rec)
                return 0;

        seq_printf(m, "%ps", (void *)rec->ip);
        if (iter->flags & FTRACE_ITER_ENABLED) {
                struct ftrace_ops *ops;

                seq_printf(m, " (%ld)%s%s",
                           ftrace_rec_count(rec),
                           rec->flags & FTRACE_FL_REGS ? " R" : "  ",
                           rec->flags & FTRACE_FL_IPMODIFY ? " I" : "  ");
                if (rec->flags & FTRACE_FL_TRAMP_EN) {
                        ops = ftrace_find_tramp_ops_any(rec);
                        if (ops) {
                                do {
                                        seq_printf(m, "\ttramp: %pS (%pS)",
                                                   (void *)ops->trampoline,
                                                   (void *)ops->func);
                                        add_trampoline_func(m, ops, rec);
                                        ops = ftrace_find_tramp_ops_next(rec, ops);
                                } while (ops);
                        } else
                                seq_puts(m, "\ttramp: ERROR!");
                } else {
                        add_trampoline_func(m, NULL, rec);
                }
        }       

        seq_putc(m, '\n');

        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;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));
        if (iter) {
                iter->pg = ftrace_pages_start;
                iter->ops = &global_ops;
        }

        return iter ? 0 : -ENOMEM;
}

static int
ftrace_enabled_open(struct inode *inode, struct file *file)
{
        struct ftrace_iterator *iter;

        iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));
        if (iter) {
                iter->pg = ftrace_pages_start;
                iter->flags = FTRACE_ITER_ENABLED;
                iter->ops = &global_ops;
        }

        return iter ? 0 : -ENOMEM;
}

/**
 * ftrace_regex_open - initialize function tracer filter files
 * @ops: The ftrace_ops that hold the hash filters
 * @flag: The type of filter to process
 * @inode: The inode, usually passed in to your open routine
 * @file: The file, usually passed in to your open routine
 *
 * ftrace_regex_open() initializes the filter files for the
 * @ops. Depending on @flag it may process the filter hash or
 * the notrace hash of @ops. With this called from the open
 * routine, you can use ftrace_filter_write() for the write
 * routine if @flag has FTRACE_ITER_FILTER set, or
 * ftrace_notrace_write() if @flag has FTRACE_ITER_NOTRACE set.
 * tracing_lseek() should be used as the lseek routine, and
 * release must call ftrace_regex_release().
 */
int
ftrace_regex_open(struct ftrace_ops *ops, int flag,
                  struct inode *inode, struct file *file)
{
        struct ftrace_iterator *iter;
        struct ftrace_hash *hash;
        int ret = 0;

        ftrace_ops_init(ops);

        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;
        }

        iter->ops = ops;
        iter->flags = flag;

        mutex_lock(&ops->func_hash->regex_lock);

        if (flag & FTRACE_ITER_NOTRACE)
                hash = ops->func_hash->notrace_hash;
        else
                hash = ops->func_hash->filter_hash;

        if (file->f_mode & FMODE_WRITE) {
                const int size_bits = FTRACE_HASH_DEFAULT_BITS;

                if (file->f_flags & O_TRUNC)
                        iter->hash = alloc_ftrace_hash(size_bits);
                else
                        iter->hash = alloc_and_copy_ftrace_hash(size_bits, hash);

                if (!iter->hash) {
                        trace_parser_put(&iter->parser);
                        kfree(iter);
                        ret = -ENOMEM;
                        goto out_unlock;
                }
        }

        if (file->f_mode & FMODE_READ) {
                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 {
                        /* Failed */
                        free_ftrace_hash(iter->hash);
                        trace_parser_put(&iter->parser);
                        kfree(iter);
                }
        } else
                file->private_data = iter;

 out_unlock:
        mutex_unlock(&ops->func_hash->regex_lock);

        return ret;
}

static int
ftrace_filter_open(struct inode *inode, struct file *file)
{
        struct ftrace_ops *ops = inode->i_private;

        return ftrace_regex_open(ops,
                        FTRACE_ITER_FILTER | FTRACE_ITER_DO_HASH,
                        inode, file);
}

static int
ftrace_notrace_open(struct inode *inode, struct file *file)
{
        struct ftrace_ops *ops = inode->i_private;

        return ftrace_regex_open(ops, FTRACE_ITER_NOTRACE,
                                 inode, file);
}

/* Type for quick search ftrace basic regexes (globs) from filter_parse_regex */
struct ftrace_glob {
        char *search;
        unsigned len;
        int type;
};

static int ftrace_match(char *str, struct ftrace_glob *g)
{
        int matched = 0;
        int slen;

        switch (g->type) {
        case MATCH_FULL:
                if (strcmp(str, g->search) == 0)
                        matched = 1;
                break;
        case MATCH_FRONT_ONLY:
                if (strncmp(str, g->search, g->len) == 0)
                        matched = 1;
                break;
        case MATCH_MIDDLE_ONLY:
                if (strstr(str, g->search))
                        matched = 1;
                break;
        case MATCH_END_ONLY:
                slen = strlen(str);
                if (slen >= g->len &&
                    memcmp(str + slen - g->len, g->search, g->len) == 0)
                        matched = 1;
                break;
        }

        return matched;
}

static int
enter_record(struct ftrace_hash *hash, struct dyn_ftrace *rec, int clear_filter)
{
        struct ftrace_func_entry *entry;
        int ret = 0;

        entry = ftrace_lookup_ip(hash, rec->ip);
        if (clear_filter) {
                /* Do nothing if it doesn't exist */
                if (!entry)
                        return 0;

                free_hash_entry(hash, entry);
        } else {
                /* Do nothing if it exists */
                if (entry)
                        return 0;

                ret = add_hash_entry(hash, rec->ip);
        }
        return ret;
}

static int
ftrace_match_record(struct dyn_ftrace *rec, struct ftrace_glob *func_g,
                struct ftrace_glob *mod_g, int exclude_mod)
{
        char str[KSYM_SYMBOL_LEN];
        char *modname;

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

        if (mod_g) {
                int mod_matches = (modname) ? ftrace_match(modname, mod_g) : 0;

                /* blank module name to match all modules */
                if (!mod_g->len) {
                        /* blank module globbing: modname xor exclude_mod */
                        if ((!exclude_mod) != (!modname))
                                goto func_match;
                        return 0;
                }

                /* not matching the module */
                if (!modname || !mod_matches) {
                        if (exclude_mod)
                                goto func_match;
                        else
                                return 0;
                }

                if (mod_matches && exclude_mod)
                        return 0;

func_match:
                /* blank search means to match all funcs in the mod */
                if (!func_g->len)
                        return 1;
        }

        return ftrace_match(str, func_g);
}

static int
match_records(struct ftrace_hash *hash, char *func, int len, char *mod)
{
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;
        struct ftrace_glob func_g = { .type = MATCH_FULL };
        struct ftrace_glob mod_g = { .type = MATCH_FULL };
        struct ftrace_glob *mod_match = (mod) ? &mod_g : NULL;
        int exclude_mod = 0;
        int found = 0;
        int ret;
        int clear_filter;

        if (func) {
                func_g.type = filter_parse_regex(func, len, &func_g.search,
                                                 &clear_filter);
                func_g.len = strlen(func_g.search);
        }

        if (mod) {
                mod_g.type = filter_parse_regex(mod, strlen(mod),
                                &mod_g.search, &exclude_mod);
                mod_g.len = strlen(mod_g.search);
        }

        mutex_lock(&ftrace_lock);

        if (unlikely(ftrace_disabled))
                goto out_unlock;

        do_for_each_ftrace_rec(pg, rec) {
                if (ftrace_match_record(rec, &func_g, mod_match, exclude_mod)) {
                        ret = enter_record(hash, rec, clear_filter);
                        if (ret < 0) {
                                found = ret;
                                goto out_unlock;
                        }
                        found = 1;
                }
        } while_for_each_ftrace_rec();
 out_unlock:
        mutex_unlock(&ftrace_lock);

        return found;
}

static int
ftrace_match_records(struct ftrace_hash *hash, char *buff, int len)
{
        return match_records(hash, buff, len, NULL);
}


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

static int
ftrace_mod_callback(struct ftrace_hash *hash,
                    char *func, char *cmd, char *module, int enable)
{
        int ret;

        /*
         * 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.
         */
        ret = match_records(hash, func, strlen(func), module);
        if (!ret)
                return -EINVAL;
        if (ret < 0)
                return ret;
        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);
}
core_initcall(ftrace_mod_cmd_init);

static void function_trace_probe_call(unsigned long ip, unsigned long parent_ip,
                                      struct ftrace_ops *op, struct pt_regs *pt_regs)
{
        struct ftrace_func_probe *entry;
        struct hlist_head *hhd;
        unsigned long key;

        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.
         */
        preempt_disable_notrace();
        hlist_for_each_entry_rcu_notrace(entry, hhd, node) {
                if (entry->ip == ip)
                        entry->ops->func(ip, parent_ip, &entry->data);
        }
        preempt_enable_notrace();
}

static struct ftrace_ops trace_probe_ops __read_mostly =
{
        .func           = function_trace_probe_call,
        .flags          = FTRACE_OPS_FL_INITIALIZED,
        INIT_OPS_HASH(trace_probe_ops)
};

static int ftrace_probe_registered;

static void __enable_ftrace_function_probe(struct ftrace_ops_hash *old_hash)
{
        int ret;
        int i;

        if (ftrace_probe_registered) {
                /* still need to update the function call sites */
                if (ftrace_enabled)
                        ftrace_run_modify_code(&trace_probe_ops, FTRACE_UPDATE_CALLS,
                                               old_hash);
                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;

        ret = ftrace_startup(&trace_probe_ops, 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 */
        ftrace_shutdown(&trace_probe_ops, 0);

        ftrace_probe_registered = 0;
}


static void ftrace_free_entry(struct ftrace_func_probe *entry)
{
        if (entry->ops->free)
                entry->ops->free(entry->ops, entry->ip, &entry->data);
        kfree(entry);
}

int
register_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
                              void *data)
{
        struct ftrace_ops_hash old_hash_ops;
        struct ftrace_func_probe *entry;
        struct ftrace_glob func_g;
        struct ftrace_hash **orig_hash = &trace_probe_ops.func_hash->filter_hash;
        struct ftrace_hash *old_hash = *orig_hash;
        struct ftrace_hash *hash;
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;
        int not;
        unsigned long key;
        int count = 0;
        int ret;

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

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

        mutex_lock(&trace_probe_ops.func_hash->regex_lock);

        old_hash_ops.filter_hash = old_hash;
        /* Probes only have filters */
        old_hash_ops.notrace_hash = NULL;

        hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, old_hash);
        if (!hash) {
                count = -ENOMEM;
                goto out;
        }

        if (unlikely(ftrace_disabled)) {
                count = -ENODEV;
                goto out;
        }

        mutex_lock(&ftrace_lock);

        do_for_each_ftrace_rec(pg, rec) {

                if (!ftrace_match_record(rec, &func_g, NULL, 0))
                        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->init) {
                        if (ops->init(ops, rec->ip, &entry->data) < 0) {
                                /* caller does not like this func */
                                kfree(entry);
                                continue;
                        }
                }

                ret = enter_record(hash, rec, 0);
                if (ret < 0) {
                        kfree(entry);
                        count = ret;
                        goto out_unlock;
                }

                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();

        ret = ftrace_hash_move(&trace_probe_ops, 1, orig_hash, hash);

        __enable_ftrace_function_probe(&old_hash_ops);

        if (!ret)
                free_ftrace_hash_rcu(old_hash);
        else
                count = ret;

 out_unlock:
        mutex_unlock(&ftrace_lock);
 out:
        mutex_unlock(&trace_probe_ops.func_hash->regex_lock);
        free_ftrace_hash(hash);

        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_entry *rec_entry;
        struct ftrace_func_probe *entry;
        struct ftrace_func_probe *p;
        struct ftrace_glob func_g;
        struct ftrace_hash **orig_hash = &trace_probe_ops.func_hash->filter_hash;
        struct ftrace_hash *old_hash = *orig_hash;
        struct list_head free_list;
        struct ftrace_hash *hash;
        struct hlist_node *tmp;
        char str[KSYM_SYMBOL_LEN];
        int i, ret;

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

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

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

        mutex_lock(&trace_probe_ops.func_hash->regex_lock);

        hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
        if (!hash)
                /* Hmm, should report this somehow */
                goto out_unlock;

        INIT_LIST_HEAD(&free_list);

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

                hlist_for_each_entry_safe(entry, 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 (func_g.search) {
                                kallsyms_lookup(entry->ip, NULL, NULL,
                                                NULL, str);
                                if (!ftrace_match(str, &func_g))
                                        continue;
                        }

                        rec_entry = ftrace_lookup_ip(hash, entry->ip);
                        /* It is possible more than one entry had this ip */
                        if (rec_entry)
                                free_hash_entry(hash, rec_entry);

                        hlist_del_rcu(&entry->node);
                        list_add(&entry->free_list, &free_list);
                }
        }
        mutex_lock(&ftrace_lock);
        __disable_ftrace_function_probe();
        /*
         * Remove after the disable is called. Otherwise, if the last
         * probe is removed, a null hash means *all enabled*.
         */
        ret = ftrace_hash_move(&trace_probe_ops, 1, orig_hash, hash);
        synchronize_sched();
        if (!ret)
                free_ftrace_hash_rcu(old_hash);

        list_for_each_entry_safe(entry, p, &free_list, free_list) {
                list_del(&entry->free_list);
                ftrace_free_entry(entry);
        }
        mutex_unlock(&ftrace_lock);

 out_unlock:
        mutex_unlock(&trace_probe_ops.func_hash->regex_lock);
        free_ftrace_hash(hash);
}

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);

/*
 * Currently we only register ftrace commands from __init, so mark this
 * __init too.
 */
__init 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;
}

/*
 * Currently we only unregister ftrace commands from __init, so mark
 * this __init too.
 */
__init 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(struct ftrace_hash *hash,
                                char *buff, int len, int enable)
{
        char *func, *command, *next = buff;
        struct ftrace_func_command *p;
        int ret = -EINVAL;

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

        if (!next) {
                ret = ftrace_match_records(hash, func, len);
                if (!ret)
                        ret = -EINVAL;
                if (ret < 0)
                        return ret;
                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(hash, 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;

        if (file->f_mode & FMODE_READ) {
                struct seq_file *m = file->private_data;
                iter = m->private;
        } else
                iter = file->private_data;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        /* iter->hash is a local copy, so we don't need regex_lock */

        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(iter->hash, parser->buffer,
                                           parser->idx, enable);
                trace_parser_clear(parser);
                if (ret < 0)
                        goto out;
        }

        ret = read;
 out:
        return ret;
}

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);
}

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 int
ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove)
{
        struct ftrace_func_entry *entry;

        if (!ftrace_location(ip))
                return -EINVAL;

        if (remove) {
                entry = ftrace_lookup_ip(hash, ip);
                if (!entry)
                        return -ENOENT;
                free_hash_entry(hash, entry);
                return 0;
        }

        return add_hash_entry(hash, ip);
}

static void ftrace_ops_update_code(struct ftrace_ops *ops,
                                   struct ftrace_ops_hash *old_hash)
{
        struct ftrace_ops *op;

        if (!ftrace_enabled)
                return;

        if (ops->flags & FTRACE_OPS_FL_ENABLED) {
                ftrace_run_modify_code(ops, FTRACE_UPDATE_CALLS, old_hash);
                return;
        }

        /*
         * If this is the shared global_ops filter, then we need to
         * check if there is another ops that shares it, is enabled.
         * If so, we still need to run the modify code.
         */
        if (ops->func_hash != &global_ops.local_hash)
                return;

        do_for_each_ftrace_op(op, ftrace_ops_list) {
                if (op->func_hash == &global_ops.local_hash &&
                    op->flags & FTRACE_OPS_FL_ENABLED) {
                        ftrace_run_modify_code(op, FTRACE_UPDATE_CALLS, old_hash);
                        /* Only need to do this once */
                        return;
                }
        } while_for_each_ftrace_op(op);
}

static int
ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len,
                unsigned long ip, int remove, int reset, int enable)
{
        struct ftrace_hash **orig_hash;
        struct ftrace_ops_hash old_hash_ops;
        struct ftrace_hash *old_hash;
        struct ftrace_hash *hash;
        int ret;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        mutex_lock(&ops->func_hash->regex_lock);

        if (enable)
                orig_hash = &ops->func_hash->filter_hash;
        else
                orig_hash = &ops->func_hash->notrace_hash;

        if (reset)
                hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
        else
                hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);

        if (!hash) {
                ret = -ENOMEM;
                goto out_regex_unlock;
        }

        if (buf && !ftrace_match_records(hash, buf, len)) {
                ret = -EINVAL;
                goto out_regex_unlock;
        }
        if (ip) {
                ret = ftrace_match_addr(hash, ip, remove);
                if (ret < 0)
                        goto out_regex_unlock;
        }

        mutex_lock(&ftrace_lock);
        old_hash = *orig_hash;
        old_hash_ops.filter_hash = ops->func_hash->filter_hash;
        old_hash_ops.notrace_hash = ops->func_hash->notrace_hash;
        ret = ftrace_hash_move(ops, enable, orig_hash, hash);
        if (!ret) {
                ftrace_ops_update_code(ops, &old_hash_ops);
                free_ftrace_hash_rcu(old_hash);
        }
        mutex_unlock(&ftrace_lock);

 out_regex_unlock:
        mutex_unlock(&ops->func_hash->regex_lock);

        free_ftrace_hash(hash);
        return ret;
}

static int
ftrace_set_addr(struct ftrace_ops *ops, unsigned long ip, int remove,
                int reset, int enable)
{
        return ftrace_set_hash(ops, 0, 0, ip, remove, reset, enable);
}

/**
 * ftrace_set_filter_ip - set a function to filter on in ftrace by address
 * @ops - the ops to set the filter with
 * @ip - the address to add to or remove from the filter.
 * @remove - non zero to remove the ip from the filter
 * @reset - non zero to reset all filters before applying this filter.
 *
 * Filters denote which functions should be enabled when tracing is enabled
 * If @ip is NULL, it failes to update filter.
 */
int ftrace_set_filter_ip(struct ftrace_ops *ops, unsigned long ip,
                         int remove, int reset)
{
        ftrace_ops_init(ops);
        return ftrace_set_addr(ops, ip, remove, reset, 1);
}
EXPORT_SYMBOL_GPL(ftrace_set_filter_ip);

static int
ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
                 int reset, int enable)
{
        return ftrace_set_hash(ops, buf, len, 0, 0, reset, enable);
}

/**
 * ftrace_set_filter - set a function to filter on in ftrace
 * @ops - the ops to set the filter with
 * @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.
 */
int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
                       int len, int reset)
{
        ftrace_ops_init(ops);
        return ftrace_set_regex(ops, buf, len, reset, 1);
}
EXPORT_SYMBOL_GPL(ftrace_set_filter);

/**
 * ftrace_set_notrace - set a function to not trace in ftrace
 * @ops - the ops to set the notrace filter with
 * @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.
 */
int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
                        int len, int reset)
{
        ftrace_ops_init(ops);
        return ftrace_set_regex(ops, buf, len, reset, 0);
}
EXPORT_SYMBOL_GPL(ftrace_set_notrace);
/**
 * ftrace_set_global_filter - set a function to filter on with global tracers
 * @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_global_filter(unsigned char *buf, int len, int reset)
{
        ftrace_set_regex(&global_ops, buf, len, reset, 1);
}
EXPORT_SYMBOL_GPL(ftrace_set_global_filter);

/**
 * ftrace_set_global_notrace - set a function to not trace with global tracers
 * @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_global_notrace(unsigned char *buf, int len, int reset)
{
        ftrace_set_regex(&global_ops, buf, len, reset, 0);
}
EXPORT_SYMBOL_GPL(ftrace_set_global_notrace);

/*
 * 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;

/* Used by function selftest to not test if filter is set */
bool ftrace_filter_param __initdata;

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

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

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static char ftrace_graph_buf[FTRACE_FILTER_SIZE] __initdata;
static char ftrace_graph_notrace_buf[FTRACE_FILTER_SIZE] __initdata;
static int ftrace_set_func(unsigned long *array, int *idx, int size, char *buffer);

static unsigned long save_global_trampoline;
static unsigned long save_global_flags;

static int __init set_graph_function(char *str)
{
        strlcpy(ftrace_graph_buf, str, FTRACE_FILTER_SIZE);
        return 1;
}
__setup("ftrace_graph_filter=", set_graph_function);

static int __init set_graph_notrace_function(char *str)
{
        strlcpy(ftrace_graph_notrace_buf, str, FTRACE_FILTER_SIZE);
        return 1;
}
__setup("ftrace_graph_notrace=", set_graph_notrace_function);

static void __init set_ftrace_early_graph(char *buf, int enable)
{
        int ret;
        char *func;
        unsigned long *table = ftrace_graph_funcs;
        int *count = &ftrace_graph_count;

        if (!enable) {
                table = ftrace_graph_notrace_funcs;
                count = &ftrace_graph_notrace_count;
        }

        while (buf) {
                func = strsep(&buf, ",");
                /* we allow only one expression at a time */
                ret = ftrace_set_func(table, count, FTRACE_GRAPH_MAX_FUNCS, func);
                if (ret)
                        printk(KERN_DEBUG "ftrace: function %s not "
                                          "traceable\n", func);
        }
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

void __init
ftrace_set_early_filter(struct ftrace_ops *ops, char *buf, int enable)
{
        char *func;

        ftrace_ops_init(ops);

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

static void __init set_ftrace_early_filters(void)
{
        if (ftrace_filter_buf[0])
                ftrace_set_early_filter(&global_ops, ftrace_filter_buf, 1);
        if (ftrace_notrace_buf[0])
                ftrace_set_early_filter(&global_ops, ftrace_notrace_buf, 0);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        if (ftrace_graph_buf[0])
                set_ftrace_early_graph(ftrace_graph_buf, 1);
        if (ftrace_graph_notrace_buf[0])
                set_ftrace_early_graph(ftrace_graph_notrace_buf, 0);
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
}

int ftrace_regex_release(struct inode *inode, struct file *file)
{
        struct seq_file *m = (struct seq_file *)file->private_data;
        struct ftrace_ops_hash old_hash_ops;
        struct ftrace_iterator *iter;
        struct ftrace_hash **orig_hash;
        struct ftrace_hash *old_hash;
        struct trace_parser *parser;
        int filter_hash;
        int ret;

        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(iter->hash, parser->buffer, parser->idx);
        }

        trace_parser_put(parser);

        mutex_lock(&iter->ops->func_hash->regex_lock);

        if (file->f_mode & FMODE_WRITE) {
                filter_hash = !!(iter->flags & FTRACE_ITER_FILTER);

                if (filter_hash)
                        orig_hash = &iter->ops->func_hash->filter_hash;
                else
                        orig_hash = &iter->ops->func_hash->notrace_hash;

                mutex_lock(&ftrace_lock);
                old_hash = *orig_hash;
                old_hash_ops.filter_hash = iter->ops->func_hash->filter_hash;
                old_hash_ops.notrace_hash = iter->ops->func_hash->notrace_hash;
                ret = ftrace_hash_move(iter->ops, filter_hash,
                                       orig_hash, iter->hash);
                if (!ret) {
                        ftrace_ops_update_code(iter->ops, &old_hash_ops);
                        free_ftrace_hash_rcu(old_hash);
                }
                mutex_unlock(&ftrace_lock);
        }

        mutex_unlock(&iter->ops->func_hash->regex_lock);
        free_ftrace_hash(iter->hash);
        kfree(iter);

        return 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_enabled_fops = {
        .open = ftrace_enabled_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 = tracing_lseek,
        .release = ftrace_regex_release,
};

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

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

static DEFINE_MUTEX(graph_lock);

int ftrace_graph_count;
int ftrace_graph_notrace_count;
unsigned long ftrace_graph_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;
unsigned long ftrace_graph_notrace_funcs[FTRACE_GRAPH_MAX_FUNCS] __read_mostly;

struct ftrace_graph_data {
        unsigned long *table;
        size_t size;
        int *count;
        const struct seq_operations *seq_ops;
};

static void *
__g_next(struct seq_file *m, loff_t *pos)
{
        struct ftrace_graph_data *fgd = m->private;

        if (*pos >= *fgd->count)
                return NULL;
        return &fgd->table[*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)
{
        struct ftrace_graph_data *fgd = m->private;

        mutex_lock(&graph_lock);

        /* Nothing, tell g_show to print all functions are enabled */
        if (!*fgd->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) {
                struct ftrace_graph_data *fgd = m->private;

                if (fgd->table == ftrace_graph_funcs)
                        seq_puts(m, "#### all functions enabled ####\n");
                else
                        seq_puts(m, "#### no functions disabled ####\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,
                    struct ftrace_graph_data *fgd)
{
        int ret = 0;

        mutex_lock(&graph_lock);
        if ((file->f_mode & FMODE_WRITE) &&
            (file->f_flags & O_TRUNC)) {
                *fgd->count = 0;
                memset(fgd->table, 0, fgd->size * sizeof(*fgd->table));
        }
        mutex_unlock(&graph_lock);

        if (file->f_mode & FMODE_READ) {
                ret = seq_open(file, fgd->seq_ops);
                if (!ret) {
                        struct seq_file *m = file->private_data;
                        m->private = fgd;
                }
        } else
                file->private_data = fgd;

        return ret;
}

static int
ftrace_graph_open(struct inode *inode, struct file *file)
{
        struct ftrace_graph_data *fgd;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        fgd = kmalloc(sizeof(*fgd), GFP_KERNEL);
        if (fgd == NULL)
                return -ENOMEM;

        fgd->table = ftrace_graph_funcs;
        fgd->size = FTRACE_GRAPH_MAX_FUNCS;
        fgd->count = &ftrace_graph_count;
        fgd->seq_ops = &ftrace_graph_seq_ops;

        return __ftrace_graph_open(inode, file, fgd);
}

static int
ftrace_graph_notrace_open(struct inode *inode, struct file *file)
{
        struct ftrace_graph_data *fgd;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        fgd = kmalloc(sizeof(*fgd), GFP_KERNEL);
        if (fgd == NULL)
                return -ENOMEM;

        fgd->table = ftrace_graph_notrace_funcs;
        fgd->size = FTRACE_GRAPH_MAX_FUNCS;
        fgd->count = &ftrace_graph_notrace_count;
        fgd->seq_ops = &ftrace_graph_seq_ops;

        return __ftrace_graph_open(inode, file, fgd);
}

static int
ftrace_graph_release(struct inode *inode, struct file *file)
{
        if (file->f_mode & FMODE_READ) {
                struct seq_file *m = file->private_data;

                kfree(m->private);
                seq_release(inode, file);
        } else {
                kfree(file->private_data);
        }

        return 0;
}

static int
ftrace_set_func(unsigned long *array, int *idx, int size, char *buffer)
{
        struct ftrace_glob func_g;
        struct dyn_ftrace *rec;
        struct ftrace_page *pg;
        int fail = 1;
        int not;
        bool exists;
        int i;

        /* decode regex */
        func_g.type = filter_parse_regex(buffer, strlen(buffer),
                                         &func_g.search, &not);
        if (!not && *idx >= size)
                return -EBUSY;

        func_g.len = strlen(func_g.search);

        mutex_lock(&ftrace_lock);

        if (unlikely(ftrace_disabled)) {
                mutex_unlock(&ftrace_lock);
                return -ENODEV;
        }

        do_for_each_ftrace_rec(pg, rec) {

                if (ftrace_match_record(rec, &func_g, NULL, 0)) {
                        /* if it is in the array */
                        exists = false;
                        for (i = 0; i < *idx; i++) {
                                if (array[i] == rec->ip) {
                                        exists = true;
                                        break;
                                }
                        }

                        if (!not) {
                                fail = 0;
                                if (!exists) {
                                        array[(*idx)++] = rec->ip;
                                        if (*idx >= size)
                                                goto out;
                                }
                        } else {
                                if (exists) {
                                        array[i] = array[--(*idx)];
                                        array[*idx] = 0;
                                        fail = 0;
                                }
                        }
                }
        } while_for_each_ftrace_rec();
out:
        mutex_unlock(&ftrace_lock);

        if (fail)
                return -EINVAL;

        return 0;
}

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 = 0;
        struct ftrace_graph_data *fgd = file->private_data;

        if (!cnt)
                return 0;

        if (trace_parser_get_init(&parser, FTRACE_BUFF_MAX))
                return -ENOMEM;

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

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

                mutex_lock(&graph_lock);

                /* we allow only one expression at a time */
                ret = ftrace_set_func(fgd->table, fgd->count, fgd->size,
                                      parser.buffer);

                mutex_unlock(&graph_lock);
        }

        if (!ret)
                ret = read;

        trace_parser_put(&parser);

        return ret;
}

static const struct file_operations ftrace_graph_fops = {
        .open           = ftrace_graph_open,
        .read           = seq_read,
        .write          = ftrace_graph_write,
        .llseek         = tracing_lseek,
        .release        = ftrace_graph_release,
};

static const struct file_operations ftrace_graph_notrace_fops = {
        .open           = ftrace_graph_notrace_open,
        .read           = seq_read,
        .write          = ftrace_graph_write,
        .llseek         = tracing_lseek,
        .release        = ftrace_graph_release,
};
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

void ftrace_create_filter_files(struct ftrace_ops *ops,
                                struct dentry *parent)
{

        trace_create_file("set_ftrace_filter", 0644, parent,
                          ops, &ftrace_filter_fops);

        trace_create_file("set_ftrace_notrace", 0644, parent,
                          ops, &ftrace_notrace_fops);
}

/*
 * The name "destroy_filter_files" is really a misnomer. Although
 * in the future, it may actualy delete the files, but this is
 * really intended to make sure the ops passed in are disabled
 * and that when this function returns, the caller is free to
 * free the ops.
 *
 * The "destroy" name is only to match the "create" name that this
 * should be paired with.
 */
void ftrace_destroy_filter_files(struct ftrace_ops *ops)
{
        mutex_lock(&ftrace_lock);
        if (ops->flags & FTRACE_OPS_FL_ENABLED)
                ftrace_shutdown(ops, 0);
        ops->flags |= FTRACE_OPS_FL_DELETED;
        mutex_unlock(&ftrace_lock);
}

static __init int ftrace_init_dyn_tracefs(struct dentry *d_tracer)
{

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

        trace_create_file("enabled_functions", 0444,
                        d_tracer, NULL, &ftrace_enabled_fops);

        ftrace_create_filter_files(&global_ops, d_tracer);

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

        return 0;
}

static int ftrace_cmp_ips(const void *a, const void *b)
{
        const unsigned long *ipa = a;
        const unsigned long *ipb = b;

        if (*ipa > *ipb)
                return 1;
        if (*ipa < *ipb)
                return -1;
        return 0;
}

static int ftrace_process_locs(struct module *mod,
                               unsigned long *start,
                               unsigned long *end)
{
        struct ftrace_page *start_pg;
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;
        unsigned long count;
        unsigned long *p;
        unsigned long addr;
        unsigned long flags = 0; /* Shut up gcc */
        int ret = -ENOMEM;

        count = end - start;

        if (!count)
                return 0;

        sort(start, count, sizeof(*start),
             ftrace_cmp_ips, NULL);

        start_pg = ftrace_allocate_pages(count);
        if (!start_pg)
                return -ENOMEM;

        mutex_lock(&ftrace_lock);

        /*
         * Core and each module needs their own pages, as
         * modules will free them when they are removed.
         * Force a new page to be allocated for modules.
         */
        if (!mod) {
                WARN_ON(ftrace_pages || ftrace_pages_start);
                /* First initialization */
                ftrace_pages = ftrace_pages_start = start_pg;
        } else {
                if (!ftrace_pages)
                        goto out;

                if (WARN_ON(ftrace_pages->next)) {
                        /* Hmm, we have free pages? */
                        while (ftrace_pages->next)
                                ftrace_pages = ftrace_pages->next;
                }

                ftrace_pages->next = start_pg;
        }

        p = start;
        pg = start_pg;
        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;

                if (pg->index == pg->size) {
                        /* We should have allocated enough */
                        if (WARN_ON(!pg->next))
                                break;
                        pg = pg->next;
                }

                rec = &pg->records[pg->index++];
                rec->ip = addr;
        }

        /* We should have used all pages */
        WARN_ON(pg->next);

        /* Assign the last page to ftrace_pages */
        ftrace_pages = pg;

        /*
         * We only need to disable interrupts on start up
         * because we are modifying code that an interrupt
         * may execute, and the modification is not atomic.
         * But for modules, nothing runs the code we modify
         * until we are finished with it, and there's no
         * reason to cause large interrupt latencies while we do it.
         */
        if (!mod)
                local_irq_save(flags);
        ftrace_update_code(mod, start_pg);
        if (!mod)
                local_irq_restore(flags);
        ret = 0;
 out:
        mutex_unlock(&ftrace_lock);

        return ret;
}

#ifdef CONFIG_MODULES

#define next_to_ftrace_page(p) container_of(p, struct ftrace_page, next)

static int referenced_filters(struct dyn_ftrace *rec)
{
        struct ftrace_ops *ops;
        int cnt = 0;

        for (ops = ftrace_ops_list; ops != &ftrace_list_end; ops = ops->next) {
                if (ops_references_rec(ops, rec))
                    cnt++;
        }

        return cnt;
}

void ftrace_release_mod(struct module *mod)
{
        struct dyn_ftrace *rec;
        struct ftrace_page **last_pg;
        struct ftrace_page *pg;
        int order;

        mutex_lock(&ftrace_lock);

        if (ftrace_disabled)
                goto out_unlock;

        /*
         * Each module has its own ftrace_pages, remove
         * them from the list.
         */
        last_pg = &ftrace_pages_start;
        for (pg = ftrace_pages_start; pg; pg = *last_pg) {
                rec = &pg->records[0];
                if (within_module_core(rec->ip, mod)) {
                        /*
                         * As core pages are first, the first
                         * page should never be a module page.
                         */
                        if (WARN_ON(pg == ftrace_pages_start))
                                goto out_unlock;

                        /* Check if we are deleting the last page */
                        if (pg == ftrace_pages)
                                ftrace_pages = next_to_ftrace_page(last_pg);

                        *last_pg = pg->next;
                        order = get_count_order(pg->size / ENTRIES_PER_PAGE);
                        free_pages((unsigned long)pg->records, order);
                        kfree(pg);
                } else
                        last_pg = &pg->next;
        }
 out_unlock:
        mutex_unlock(&ftrace_lock);
}

void ftrace_module_enable(struct module *mod)
{
        struct dyn_ftrace *rec;
        struct ftrace_page *pg;

        mutex_lock(&ftrace_lock);

        if (ftrace_disabled)
                goto out_unlock;

        /*
         * If the tracing is enabled, go ahead and enable the record.
         *
         * The reason not to enable the record immediatelly is the
         * inherent check of ftrace_make_nop/ftrace_make_call for
         * correct previous instructions.  Making first the NOP
         * conversion puts the module to the correct state, thus
         * passing the ftrace_make_call check.
         *
         * We also delay this to after the module code already set the
         * text to read-only, as we now need to set it back to read-write
         * so that we can modify the text.
         */
        if (ftrace_start_up)
                ftrace_arch_code_modify_prepare();

        do_for_each_ftrace_rec(pg, rec) {
                int cnt;
                /*
                 * do_for_each_ftrace_rec() is a double loop.
                 * module text shares the pg. If a record is
                 * not part of this module, then skip this pg,
                 * which the "break" will do.
                 */
                if (!within_module_core(rec->ip, mod))
                        break;

                cnt = 0;

                /*
                 * When adding a module, we need to check if tracers are
                 * currently enabled and if they are, and can trace this record,
                 * we need to enable the module functions as well as update the
                 * reference counts for those function records.
                 */
                if (ftrace_start_up)
                        cnt += referenced_filters(rec);

                /* This clears FTRACE_FL_DISABLED */
                rec->flags = cnt;

                if (ftrace_start_up && cnt) {
                        int failed = __ftrace_replace_code(rec, 1);
                        if (failed) {
                                ftrace_bug(failed, rec);
                                goto out_loop;
                        }
                }

        } while_for_each_ftrace_rec();

 out_loop:
        if (ftrace_start_up)
                ftrace_arch_code_modify_post_process();

 out_unlock:
        mutex_unlock(&ftrace_lock);
}

void ftrace_module_init(struct module *mod)
{
        if (ftrace_disabled || !mod->num_ftrace_callsites)
                return;

        ftrace_process_locs(mod, mod->ftrace_callsites,
                            mod->ftrace_callsites + mod->num_ftrace_callsites);
}
#endif /* CONFIG_MODULES */

void __init ftrace_init(void)
{
        extern unsigned long __start_mcount_loc[];
        extern unsigned long __stop_mcount_loc[];
        unsigned long count, flags;
        int ret;

        local_irq_save(flags);
        ret = ftrace_dyn_arch_init();
        local_irq_restore(flags);
        if (ret)
                goto failed;

        count = __stop_mcount_loc - __start_mcount_loc;
        if (!count) {
                pr_info("ftrace: No functions to be traced?\n");
                goto failed;
        }

        pr_info("ftrace: allocating %ld entries in %ld pages\n",
                count, count / ENTRIES_PER_PAGE + 1);

        last_ftrace_enabled = ftrace_enabled = 1;

        ret = ftrace_process_locs(NULL,
                                  __start_mcount_loc,
                                  __stop_mcount_loc);

        set_ftrace_early_filters();

        return;
 failed:
        ftrace_disabled = 1;
}

/* Do nothing if arch does not support this */
void __weak arch_ftrace_update_trampoline(struct ftrace_ops *ops)
{
}

static void ftrace_update_trampoline(struct ftrace_ops *ops)
{

/*
 * Currently there's no safe way to free a trampoline when the kernel
 * is configured with PREEMPT. That is because a task could be preempted
 * when it jumped to the trampoline, it may be preempted for a long time
 * depending on the system load, and currently there's no way to know
 * when it will be off the trampoline. If the trampoline is freed
 * too early, when the task runs again, it will be executing on freed
 * memory and crash.
 */
#ifdef CONFIG_PREEMPT
        /* Currently, only non dynamic ops can have a trampoline */
        if (ops->flags & FTRACE_OPS_FL_DYNAMIC)
                return;
#endif

        arch_ftrace_update_trampoline(ops);
}

#else

static struct ftrace_ops global_ops = {
        .func                   = ftrace_stub,
        .flags                  = FTRACE_OPS_FL_RECURSION_SAFE |
                                  FTRACE_OPS_FL_INITIALIZED |
                                  FTRACE_OPS_FL_PID,
};

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

static inline int ftrace_init_dyn_tracefs(struct dentry *d_tracer) { return 0; }
static inline void ftrace_startup_enable(int command) { }
static inline void ftrace_startup_all(int command) { }
/* Keep as macros so we do not need to define the commands */
# define ftrace_startup(ops, command)                                   \
        ({                                                              \
                int ___ret = __register_ftrace_function(ops);           \
                if (!___ret)                                            \
                        (ops)->flags |= FTRACE_OPS_FL_ENABLED;          \
                ___ret;                                                 \
        })
# define ftrace_shutdown(ops, command)                                  \
        ({                                                              \
                int ___ret = __unregister_ftrace_function(ops);         \
                if (!___ret)                                            \
                        (ops)->flags &= ~FTRACE_OPS_FL_ENABLED;         \
                ___ret;                                                 \
        })

# define ftrace_startup_sysctl()        do { } while (0)
# define ftrace_shutdown_sysctl()       do { } while (0)

static inline int
ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
{
        return 1;
}

static void ftrace_update_trampoline(struct ftrace_ops *ops)
{
}

#endif /* CONFIG_DYNAMIC_FTRACE */

__init void ftrace_init_global_array_ops(struct trace_array *tr)
{
        tr->ops = &global_ops;
        tr->ops->private = tr;
}

void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func)
{
        /* If we filter on pids, update to use the pid function */
        if (tr->flags & TRACE_ARRAY_FL_GLOBAL) {
                if (WARN_ON(tr->ops->func != ftrace_stub))
                        printk("ftrace ops had %pS for function\n",
                               tr->ops->func);
        }
        tr->ops->func = func;
        tr->ops->private = tr;
}

void ftrace_reset_array_ops(struct trace_array *tr)
{
        tr->ops->func = ftrace_stub;
}

static inline void
__ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
                       struct ftrace_ops *ignored, struct pt_regs *regs)
{
        struct ftrace_ops *op;
        int bit;

        bit = trace_test_and_set_recursion(TRACE_LIST_START, TRACE_LIST_MAX);
        if (bit < 0)
                return;

        /*
         * Some of the ops may be dynamically allocated,
         * they must be freed after a synchronize_sched().
         */
        preempt_disable_notrace();

        do_for_each_ftrace_op(op, ftrace_ops_list) {
                /*
                 * Check the following for each ops before calling their func:
                 *  if RCU flag is set, then rcu_is_watching() must be true
                 *  if PER_CPU is set, then ftrace_function_local_disable()
                 *                          must be false
                 *  Otherwise test if the ip matches the ops filter
                 *
                 * If any of the above fails then the op->func() is not executed.
                 */
                if ((!(op->flags & FTRACE_OPS_FL_RCU) || rcu_is_watching()) &&
                    (!(op->flags & FTRACE_OPS_FL_PER_CPU) ||
                     !ftrace_function_local_disabled(op)) &&
                    ftrace_ops_test(op, ip, regs)) {
                    
                        if (FTRACE_WARN_ON(!op->func)) {
                                pr_warn("op=%p %pS\n", op, op);
                                goto out;
                        }
                        op->func(ip, parent_ip, op, regs);
                }
        } while_for_each_ftrace_op(op);
out:
        preempt_enable_notrace();
        trace_clear_recursion(bit);
}

/*
 * Some archs only support passing ip and parent_ip. Even though
 * the list function ignores the op parameter, we do not want any
 * C side effects, where a function is called without the caller
 * sending a third parameter.
 * Archs are to support both the regs and ftrace_ops at the same time.
 * If they support ftrace_ops, it is assumed they support regs.
 * If call backs want to use regs, they must either check for regs
 * being NULL, or CONFIG_DYNAMIC_FTRACE_WITH_REGS.
 * Note, CONFIG_DYNAMIC_FTRACE_WITH_REGS expects a full regs to be saved.
 * An architecture can pass partial regs with ftrace_ops and still
 * set the ARCH_SUPPORTS_FTRACE_OPS.
 */
#if ARCH_SUPPORTS_FTRACE_OPS
static void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
                                 struct ftrace_ops *op, struct pt_regs *regs)
{
        __ftrace_ops_list_func(ip, parent_ip, NULL, regs);
}
#else
static void ftrace_ops_no_ops(unsigned long ip, unsigned long parent_ip)
{
        __ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
}
#endif

/*
 * If there's only one function registered but it does not support
 * recursion, needs RCU protection and/or requires per cpu handling, then
 * this function will be called by the mcount trampoline.
 */
static void ftrace_ops_assist_func(unsigned long ip, unsigned long parent_ip,
                                   struct ftrace_ops *op, struct pt_regs *regs)
{
        int bit;

        if ((op->flags & FTRACE_OPS_FL_RCU) && !rcu_is_watching())
                return;

        bit = trace_test_and_set_recursion(TRACE_LIST_START, TRACE_LIST_MAX);
        if (bit < 0)
                return;

        preempt_disable_notrace();

        if (!(op->flags & FTRACE_OPS_FL_PER_CPU) ||
            !ftrace_function_local_disabled(op)) {
                op->func(ip, parent_ip, op, regs);
        }

        preempt_enable_notrace();
        trace_clear_recursion(bit);
}

/**
 * ftrace_ops_get_func - get the function a trampoline should call
 * @ops: the ops to get the function for
 *
 * Normally the mcount trampoline will call the ops->func, but there
 * are times that it should not. For example, if the ops does not
 * have its own recursion protection, then it should call the
 * ftrace_ops_recurs_func() instead.
 *
 * Returns the function that the trampoline should call for @ops.
 */
ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops)
{
        /*
         * If the function does not handle recursion, needs to be RCU safe,
         * or does per cpu logic, then we need to call the assist handler.
         */
        if (!(ops->flags & FTRACE_OPS_FL_RECURSION_SAFE) ||
            ops->flags & (FTRACE_OPS_FL_RCU | FTRACE_OPS_FL_PER_CPU))
                return ftrace_ops_assist_func;

        return ops->func;
}

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);
}

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

static int ftrace_pid_add(int p)
{
        struct pid *pid;
        struct ftrace_pid *fpid;
        int ret = -EINVAL;

        mutex_lock(&ftrace_lock);

        if (!p)
                pid = ftrace_swapper_pid;
        else
                pid = find_get_pid(p);

        if (!pid)
                goto out;

        ret = 0;

        list_for_each_entry(fpid, &ftrace_pids, list)
                if (fpid->pid == pid)
                        goto out_put;

        ret = -ENOMEM;

        fpid = kmalloc(sizeof(*fpid), GFP_KERNEL);
        if (!fpid)
                goto out_put;

        list_add(&fpid->list, &ftrace_pids);
        fpid->pid = pid;

        set_ftrace_pid_task(pid);

        ftrace_update_pid_func();

        ftrace_startup_all(0);

        mutex_unlock(&ftrace_lock);
        return 0;

out_put:
        if (pid != ftrace_swapper_pid)
                put_pid(pid);

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

static void ftrace_pid_reset(void)
{
        struct ftrace_pid *fpid, *safe;

        mutex_lock(&ftrace_lock);
        list_for_each_entry_safe(fpid, safe, &ftrace_pids, list) {
                struct pid *pid = fpid->pid;

                clear_ftrace_pid_task(pid);

                list_del(&fpid->list);
                kfree(fpid);
        }

        ftrace_update_pid_func();
        ftrace_startup_all(0);

        mutex_unlock(&ftrace_lock);
}

static void *fpid_start(struct seq_file *m, loff_t *pos)
{
        mutex_lock(&ftrace_lock);

        if (!ftrace_pids_enabled() && (!*pos))
                return (void *) 1;

        return seq_list_start(&ftrace_pids, *pos);
}

static void *fpid_next(struct seq_file *m, void *v, loff_t *pos)
{
        if (v == (void *)1)
                return NULL;

        return seq_list_next(v, &ftrace_pids, pos);
}

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

static int fpid_show(struct seq_file *m, void *v)
{
        const struct ftrace_pid *fpid = list_entry(v, struct ftrace_pid, list);

        if (v == (void *)1) {
                seq_puts(m, "no pid\n");
                return 0;
        }

        if (fpid->pid == ftrace_swapper_pid)
                seq_puts(m, "swapper tasks\n");
        else
                seq_printf(m, "%u\n", pid_vnr(fpid->pid));

        return 0;
}

static const struct seq_operations ftrace_pid_sops = {
        .start = fpid_start,
        .next = fpid_next,
        .stop = fpid_stop,
        .show = fpid_show,
};

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

        if ((file->f_mode & FMODE_WRITE) &&
            (file->f_flags & O_TRUNC))
                ftrace_pid_reset();

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

        return ret;
}

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

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

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

        buf[cnt] = 0;

        /*
         * Allow "echo > set_ftrace_pid" or "echo -n '' > set_ftrace_pid"
         * to clean the filter quietly.
         */
        tmp = strstrip(buf);
        if (strlen(tmp) == 0)
                return 1;

        ret = kstrtol(tmp, 10, &val);
        if (ret < 0)
                return ret;

        ret = ftrace_pid_add(val);

        return ret ? ret : cnt;
}

static int
ftrace_pid_release(struct inode *inode, struct file *file)
{
        if (file->f_mode & FMODE_READ)
                seq_release(inode, file);

        return 0;
}

static const struct file_operations ftrace_pid_fops = {
        .open           = ftrace_pid_open,
        .write          = ftrace_pid_write,
        .read           = seq_read,
        .llseek         = tracing_lseek,
        .release        = ftrace_pid_release,
};

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

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

        ftrace_init_dyn_tracefs(d_tracer);

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

        ftrace_profile_tracefs(d_tracer);

        return 0;
}
fs_initcall(ftrace_init_tracefs);

/**
 * 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();
}

/**
 * Test if ftrace is dead or not.
 */
int ftrace_is_dead(void)
{
        return ftrace_disabled;
}

/**
 * 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 = -1;

        ftrace_ops_init(ops);

        mutex_lock(&ftrace_lock);

        ret = ftrace_startup(ops, 0);

        mutex_unlock(&ftrace_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(register_ftrace_function);

/**
 * 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 = ftrace_shutdown(ops, 0);
        mutex_unlock(&ftrace_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(unregister_ftrace_function);

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

        mutex_lock(&ftrace_lock);

        if (unlikely(ftrace_disabled))
                goto out;

        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) {

                /* we are starting ftrace again */
                if (ftrace_ops_list != &ftrace_list_end)
                        update_ftrace_function();

                ftrace_startup_sysctl();

        } 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 struct ftrace_ops graph_ops = {
        .func                   = ftrace_stub,
        .flags                  = FTRACE_OPS_FL_RECURSION_SAFE |
                                   FTRACE_OPS_FL_INITIALIZED |
                                   FTRACE_OPS_FL_PID |
                                   FTRACE_OPS_FL_STUB,
#ifdef FTRACE_GRAPH_TRAMP_ADDR
        .trampoline             = FTRACE_GRAPH_TRAMP_ADDR,
        /* trampoline_size is only needed for dynamically allocated tramps */
#endif
        ASSIGN_OPS_HASH(graph_ops, &global_ops.local_hash)
};

void ftrace_graph_sleep_time_control(bool enable)
{
        fgraph_sleep_time = enable;
}

void ftrace_graph_graph_time_control(bool enable)
{
        fgraph_graph_time = enable;
}

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;
static 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(void *ignore, bool preempt,
                        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 (fgraph_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_idle_task(idle_task(cpu), cpu);
        }

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

        if (!ret) {
                ret = register_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
                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;
}

static int ftrace_graph_entry_test(struct ftrace_graph_ent *trace)
{
        if (!ftrace_ops_test(&global_ops, trace->func, NULL))
                return 0;
        return __ftrace_graph_entry(trace);
}

/*
 * The function graph tracer should only trace the functions defined
 * by set_ftrace_filter and set_ftrace_notrace. If another function
 * tracer ops is registered, the graph tracer requires testing the
 * function against the global ops, and not just trace any function
 * that any ftrace_ops registered.
 */
static void update_function_graph_func(void)
{
        struct ftrace_ops *op;
        bool do_test = false;

        /*
         * The graph and global ops share the same set of functions
         * to test. If any other ops is on the list, then
         * the graph tracing needs to test if its the function
         * it should call.
         */
        do_for_each_ftrace_op(op, ftrace_ops_list) {
                if (op != &global_ops && op != &graph_ops &&
                    op != &ftrace_list_end) {
                        do_test = true;
                        /* in double loop, break out with goto */
                        goto out;
                }
        } while_for_each_ftrace_op(op);
 out:
        if (do_test)
                ftrace_graph_entry = ftrace_graph_entry_test;
        else
                ftrace_graph_entry = __ftrace_graph_entry;
}

static struct notifier_block ftrace_suspend_notifier = {
        .notifier_call = ftrace_suspend_notifier_call,
};

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;
        }

        register_pm_notifier(&ftrace_suspend_notifier);

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

        ftrace_graph_return = retfunc;

        /*
         * Update the indirect function to the entryfunc, and the
         * function that gets called to the entry_test first. Then
         * call the update fgraph entry function to determine if
         * the entryfunc should be called directly or not.
         */
        __ftrace_graph_entry = entryfunc;
        ftrace_graph_entry = ftrace_graph_entry_test;
        update_function_graph_func();

        ret = ftrace_startup(&graph_ops, 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--;
        ftrace_graph_return = (trace_func_graph_ret_t)ftrace_stub;
        ftrace_graph_entry = ftrace_graph_entry_stub;
        __ftrace_graph_entry = ftrace_graph_entry_stub;
        ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);
        unregister_pm_notifier(&ftrace_suspend_notifier);
        unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);

#ifdef CONFIG_DYNAMIC_FTRACE
        /*
         * Function graph does not allocate the trampoline, but
         * other global_ops do. We need to reset the ALLOC_TRAMP flag
         * if one was used.
         */
        global_ops.trampoline = save_global_trampoline;
        if (save_global_flags & FTRACE_OPS_FL_ALLOC_TRAMP)
                global_ops.flags |= FTRACE_OPS_FL_ALLOC_TRAMP;
#endif

 out:
        mutex_unlock(&ftrace_lock);
}

static DEFINE_PER_CPU(struct ftrace_ret_stack *, idle_ret_stack);

static void
graph_init_task(struct task_struct *t, struct ftrace_ret_stack *ret_stack)
{
        atomic_set(&t->tracing_graph_pause, 0);
        atomic_set(&t->trace_overrun, 0);
        t->ftrace_timestamp = 0;
        /* make curr_ret_stack visible before we add the ret_stack */
        smp_wmb();
        t->ret_stack = ret_stack;
}

/*
 * Allocate a return stack for the idle task. May be the first
 * time through, or it may be done by CPU hotplug online.
 */
void ftrace_graph_init_idle_task(struct task_struct *t, int cpu)
{
        t->curr_ret_stack = -1;
        /*
         * The idle task has no parent, it either has its own
         * stack or no stack at all.
         */
        if (t->ret_stack)
                WARN_ON(t->ret_stack != per_cpu(idle_ret_stack, cpu));

        if (ftrace_graph_active) {
                struct ftrace_ret_stack *ret_stack;

                ret_stack = per_cpu(idle_ret_stack, cpu);
                if (!ret_stack) {
                        ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH
                                            * sizeof(struct ftrace_ret_stack),
                                            GFP_KERNEL);
                        if (!ret_stack)
                                return;
                        per_cpu(idle_ret_stack, cpu) = ret_stack;
                }
                graph_init_task(t, ret_stack);
        }
}

/* 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;
        t->curr_ret_stack = -1;

        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;
                graph_init_task(t, 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);
}
#endif