trace_functions_graph.c

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/*
 *
 * Function graph tracer.
 * Copyright (c) 2008-2009 Frederic Weisbecker <[email protected]>
 * Mostly borrowed from function tracer which
 * is Copyright (c) Steven Rostedt <[email protected]>
 *
 */
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/slab.h>
#include <linux/fs.h>

#include "trace.h"
#include "trace_output.h"

/* When set, irq functions will be ignored */
static int ftrace_graph_skip_irqs;

struct fgraph_cpu_data {
    pid_t       last_pid;
    int     depth;
    int     depth_irq;
    int     ignore;
    unsigned long   enter_funcs[FTRACE_RETFUNC_DEPTH];
};

struct fgraph_data {
    struct fgraph_cpu_data __percpu *cpu_data;

    /* Place to preserve last processed entry. */
    struct ftrace_graph_ent_entry   ent;
    struct ftrace_graph_ret_entry   ret;
    int             failed;
    int             cpu;
};

#define TRACE_GRAPH_INDENT  2

/* Flag options */
#define TRACE_GRAPH_PRINT_OVERRUN   0x1
#define TRACE_GRAPH_PRINT_CPU       0x2
#define TRACE_GRAPH_PRINT_OVERHEAD  0x4
#define TRACE_GRAPH_PRINT_PROC      0x8
#define TRACE_GRAPH_PRINT_DURATION  0x10
#define TRACE_GRAPH_PRINT_ABS_TIME  0x20
#define TRACE_GRAPH_PRINT_IRQS      0x40

static struct tracer_opt trace_opts[] = {
    /* Display overruns? (for self-debug purpose) */
    { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) },
    /* Display CPU ? */
    { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) },
    /* Display Overhead ? */
    { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) },
    /* Display proc name/pid */
    { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) },
    /* Display duration of execution */
    { TRACER_OPT(funcgraph-duration, TRACE_GRAPH_PRINT_DURATION) },
    /* Display absolute time of an entry */
    { TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) },
    /* Display interrupts */
    { TRACER_OPT(funcgraph-irqs, TRACE_GRAPH_PRINT_IRQS) },
    { } /* Empty entry */
};

static struct tracer_flags tracer_flags = {
    /* Don't display overruns and proc by default */
    .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD |
           TRACE_GRAPH_PRINT_DURATION | TRACE_GRAPH_PRINT_IRQS,
    .opts = trace_opts
};

static struct trace_array *graph_array;

/*
 * DURATION column is being also used to display IRQ signs,
 * following values are used by print_graph_irq and others
 * to fill in space into DURATION column.
 */
enum {
    DURATION_FILL_FULL  = -1,
    DURATION_FILL_START = -2,
    DURATION_FILL_END   = -3,
};

static enum print_line_t
print_graph_duration(unsigned long long duration, struct trace_seq *s,
             u32 flags);

/* Add a function return address to the trace stack on thread info.*/
int
ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
             unsigned long frame_pointer)
{
    unsigned long long calltime;
    int index;

    if (!current->ret_stack)
        return -EBUSY;

    /*
     * We must make sure the ret_stack is tested before we read
     * anything else.
     */
    smp_rmb();

    /* The return trace stack is full */
    if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
        atomic_inc(&current->trace_overrun);
        return -EBUSY;
    }

    calltime = trace_clock_local();

    index = ++current->curr_ret_stack;
    barrier();
    current->ret_stack[index].ret = ret;
    current->ret_stack[index].func = func;
    current->ret_stack[index].calltime = calltime;
    current->ret_stack[index].subtime = 0;
    current->ret_stack[index].fp = frame_pointer;
    *depth = index;

    return 0;
}

/* Retrieve a function return address to the trace stack on thread info.*/
static void
ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
            unsigned long frame_pointer)
{
    int index;

    index = current->curr_ret_stack;

    if (unlikely(index < 0)) {
        ftrace_graph_stop();
        WARN_ON(1);
        /* Might as well panic, otherwise we have no where to go */
        *ret = (unsigned long)panic;
        return;
    }

#if defined(CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST) && !defined(CC_USING_FENTRY)
    /*
     * The arch may choose to record the frame pointer used
     * and check it here to make sure that it is what we expect it
     * to be. If gcc does not set the place holder of the return
     * address in the frame pointer, and does a copy instead, then
     * the function graph trace will fail. This test detects this
     * case.
     *
     * Currently, x86_32 with optimize for size (-Os) makes the latest
     * gcc do the above.
     *
     * Note, -mfentry does not use frame pointers, and this test
     *  is not needed if CC_USING_FENTRY is set.
     */
    if (unlikely(current->ret_stack[index].fp != frame_pointer)) {
        ftrace_graph_stop();
        WARN(1, "Bad frame pointer: expected %lx, received %lx\n"
             "  from func %ps return to %lx\n",
             current->ret_stack[index].fp,
             frame_pointer,
             (void *)current->ret_stack[index].func,
             current->ret_stack[index].ret);
        *ret = (unsigned long)panic;
        return;
    }
#endif

    *ret = current->ret_stack[index].ret;
    trace->func = current->ret_stack[index].func;
    trace->calltime = current->ret_stack[index].calltime;
    trace->overrun = atomic_read(&current->trace_overrun);
    trace->depth = index;
}

/*
 * Send the trace to the ring-buffer.
 * @return the original return address.
 */
unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
{
    struct ftrace_graph_ret trace;
    unsigned long ret;

    ftrace_pop_return_trace(&trace, &ret, frame_pointer);
    trace.rettime = trace_clock_local();
    ftrace_graph_return(&trace);
    barrier();
    current->curr_ret_stack--;

    if (unlikely(!ret)) {
        ftrace_graph_stop();
        WARN_ON(1);
        /* Might as well panic. What else to do? */
        ret = (unsigned long)panic;
    }

    return ret;
}

int __trace_graph_entry(struct trace_array *tr,
                struct ftrace_graph_ent *trace,
                unsigned long flags,
                int pc)
{
    struct ftrace_event_call *call = &event_funcgraph_entry;
    struct ring_buffer_event *event;
    struct ring_buffer *buffer = tr->buffer;
    struct ftrace_graph_ent_entry *entry;

    if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
        return 0;

    event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT,
                      sizeof(*entry), flags, pc);
    if (!event)
        return 0;
    entry   = ring_buffer_event_data(event);
    entry->graph_ent            = *trace;
    if (!filter_current_check_discard(buffer, call, entry, event))
        ring_buffer_unlock_commit(buffer, event);

    return 1;
}

static inline int ftrace_graph_ignore_irqs(void)
{
    if (!ftrace_graph_skip_irqs || trace_recursion_test(TRACE_IRQ_BIT))
        return 0;

    return in_irq();
}

int trace_graph_entry(struct ftrace_graph_ent *trace)
{
    struct trace_array *tr = graph_array;
    struct trace_array_cpu *data;
    unsigned long flags;
    long disabled;
    int ret;
    int cpu;
    int pc;

    if (!ftrace_trace_task(current))
        return 0;

    /* trace it when it is-nested-in or is a function enabled. */
    if (!(trace->depth || ftrace_graph_addr(trace->func)) ||
          ftrace_graph_ignore_irqs())
        return 0;

    local_irq_save(flags);
    cpu = raw_smp_processor_id();
    data = tr->data[cpu];
    disabled = atomic_inc_return(&data->disabled);
    if (likely(disabled == 1)) {
        pc = preempt_count();
        ret = __trace_graph_entry(tr, trace, flags, pc);
    } else {
        ret = 0;
    }

    atomic_dec(&data->disabled);
    local_irq_restore(flags);

    return ret;
}

int trace_graph_thresh_entry(struct ftrace_graph_ent *trace)
{
    if (tracing_thresh)
        return 1;
    else
        return trace_graph_entry(trace);
}

static void
__trace_graph_function(struct trace_array *tr,
        unsigned long ip, unsigned long flags, int pc)
{
    u64 time = trace_clock_local();
    struct ftrace_graph_ent ent = {
        .func  = ip,
        .depth = 0,
    };
    struct ftrace_graph_ret ret = {
        .func     = ip,
        .depth    = 0,
        .calltime = time,
        .rettime  = time,
    };

    __trace_graph_entry(tr, &ent, flags, pc);
    __trace_graph_return(tr, &ret, flags, pc);
}

void
trace_graph_function(struct trace_array *tr,
        unsigned long ip, unsigned long parent_ip,
        unsigned long flags, int pc)
{
    __trace_graph_function(tr, ip, flags, pc);
}

void __trace_graph_return(struct trace_array *tr,
                struct ftrace_graph_ret *trace,
                unsigned long flags,
                int pc)
{
    struct ftrace_event_call *call = &event_funcgraph_exit;
    struct ring_buffer_event *event;
    struct ring_buffer *buffer = tr->buffer;
    struct ftrace_graph_ret_entry *entry;

    if (unlikely(__this_cpu_read(ftrace_cpu_disabled)))
        return;

    event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_RET,
                      sizeof(*entry), flags, pc);
    if (!event)
        return;
    entry   = ring_buffer_event_data(event);
    entry->ret              = *trace;
    if (!filter_current_check_discard(buffer, call, entry, event))
        ring_buffer_unlock_commit(buffer, event);
}

void trace_graph_return(struct ftrace_graph_ret *trace)
{
    struct trace_array *tr = graph_array;
    struct trace_array_cpu *data;
    unsigned long flags;
    long disabled;
    int cpu;
    int pc;

    local_irq_save(flags);
    cpu = raw_smp_processor_id();
    data = tr->data[cpu];
    disabled = atomic_inc_return(&data->disabled);
    if (likely(disabled == 1)) {
        pc = preempt_count();
        __trace_graph_return(tr, trace, flags, pc);
    }
    atomic_dec(&data->disabled);
    local_irq_restore(flags);
}

void set_graph_array(struct trace_array *tr)
{
    graph_array = tr;

    /* Make graph_array visible before we start tracing */

    smp_mb();
}

void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
{
    if (tracing_thresh &&
        (trace->rettime - trace->calltime < tracing_thresh))
        return;
    else
        trace_graph_return(trace);
}

static int graph_trace_init(struct trace_array *tr)
{
    int ret;

    set_graph_array(tr);
    if (tracing_thresh)
        ret = register_ftrace_graph(&trace_graph_thresh_return,
                        &trace_graph_thresh_entry);
    else
        ret = register_ftrace_graph(&trace_graph_return,
                        &trace_graph_entry);
    if (ret)
        return ret;
    tracing_start_cmdline_record();

    return 0;
}

static void graph_trace_reset(struct trace_array *tr)
{
    tracing_stop_cmdline_record();
    unregister_ftrace_graph();
}

static int max_bytes_for_cpu;

static enum print_line_t
print_graph_cpu(struct trace_seq *s, int cpu)
{
    int ret;

    /*
     * Start with a space character - to make it stand out
     * to the right a bit when trace output is pasted into
     * email:
     */
    ret = trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu);
    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    return TRACE_TYPE_HANDLED;
}

#define TRACE_GRAPH_PROCINFO_LENGTH 14

static enum print_line_t
print_graph_proc(struct trace_seq *s, pid_t pid)
{
    char comm[TASK_COMM_LEN];
    /* sign + log10(MAX_INT) + '\0' */
    char pid_str[11];
    int spaces = 0;
    int ret;
    int len;
    int i;

    trace_find_cmdline(pid, comm);
    comm[7] = '\0';
    sprintf(pid_str, "%d", pid);

    /* 1 stands for the "-" character */
    len = strlen(comm) + strlen(pid_str) + 1;

    if (len < TRACE_GRAPH_PROCINFO_LENGTH)
        spaces = TRACE_GRAPH_PROCINFO_LENGTH - len;

    /* First spaces to align center */
    for (i = 0; i < spaces / 2; i++) {
        ret = trace_seq_printf(s, " ");
        if (!ret)
            return TRACE_TYPE_PARTIAL_LINE;
    }

    ret = trace_seq_printf(s, "%s-%s", comm, pid_str);
    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    /* Last spaces to align center */
    for (i = 0; i < spaces - (spaces / 2); i++) {
        ret = trace_seq_printf(s, " ");
        if (!ret)
            return TRACE_TYPE_PARTIAL_LINE;
    }
    return TRACE_TYPE_HANDLED;
}


static enum print_line_t
print_graph_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
{
    if (!trace_seq_putc(s, ' '))
        return 0;

    return trace_print_lat_fmt(s, entry);
}

/* If the pid changed since the last trace, output this event */
static enum print_line_t
verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data)
{
    pid_t prev_pid;
    pid_t *last_pid;
    int ret;

    if (!data)
        return TRACE_TYPE_HANDLED;

    last_pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);

    if (*last_pid == pid)
        return TRACE_TYPE_HANDLED;

    prev_pid = *last_pid;
    *last_pid = pid;

    if (prev_pid == -1)
        return TRACE_TYPE_HANDLED;
/*
 * Context-switch trace line:

 ------------------------------------------
 | 1)  migration/0--1  =>  sshd-1755
 ------------------------------------------

 */
    ret = trace_seq_printf(s,
        " ------------------------------------------\n");
    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    ret = print_graph_cpu(s, cpu);
    if (ret == TRACE_TYPE_PARTIAL_LINE)
        return TRACE_TYPE_PARTIAL_LINE;

    ret = print_graph_proc(s, prev_pid);
    if (ret == TRACE_TYPE_PARTIAL_LINE)
        return TRACE_TYPE_PARTIAL_LINE;

    ret = trace_seq_printf(s, " => ");
    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    ret = print_graph_proc(s, pid);
    if (ret == TRACE_TYPE_PARTIAL_LINE)
        return TRACE_TYPE_PARTIAL_LINE;

    ret = trace_seq_printf(s,
        "\n ------------------------------------------\n\n");
    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    return TRACE_TYPE_HANDLED;
}

static struct ftrace_graph_ret_entry *
get_return_for_leaf(struct trace_iterator *iter,
        struct ftrace_graph_ent_entry *curr)
{
    struct fgraph_data *data = iter->private;
    struct ring_buffer_iter *ring_iter = NULL;
    struct ring_buffer_event *event;
    struct ftrace_graph_ret_entry *next;

    /*
     * If the previous output failed to write to the seq buffer,
     * then we just reuse the data from before.
     */
    if (data && data->failed) {
        curr = &data->ent;
        next = &data->ret;
    } else {

        ring_iter = trace_buffer_iter(iter, iter->cpu);

        /* First peek to compare current entry and the next one */
        if (ring_iter)
            event = ring_buffer_iter_peek(ring_iter, NULL);
        else {
            /*
             * We need to consume the current entry to see
             * the next one.
             */
            ring_buffer_consume(iter->tr->buffer, iter->cpu,
                        NULL, NULL);
            event = ring_buffer_peek(iter->tr->buffer, iter->cpu,
                         NULL, NULL);
        }

        if (!event)
            return NULL;

        next = ring_buffer_event_data(event);

        if (data) {
            /*
             * Save current and next entries for later reference
             * if the output fails.
             */
            data->ent = *curr;
            /*
             * If the next event is not a return type, then
             * we only care about what type it is. Otherwise we can
             * safely copy the entire event.
             */
            if (next->ent.type == TRACE_GRAPH_RET)
                data->ret = *next;
            else
                data->ret.ent.type = next->ent.type;
        }
    }

    if (next->ent.type != TRACE_GRAPH_RET)
        return NULL;

    if (curr->ent.pid != next->ent.pid ||
            curr->graph_ent.func != next->ret.func)
        return NULL;

    /* this is a leaf, now advance the iterator */
    if (ring_iter)
        ring_buffer_read(ring_iter, NULL);

    return next;
}

static int print_graph_abs_time(u64 t, struct trace_seq *s)
{
    unsigned long usecs_rem;

    usecs_rem = do_div(t, NSEC_PER_SEC);
    usecs_rem /= 1000;

    return trace_seq_printf(s, "%5lu.%06lu |  ",
            (unsigned long)t, usecs_rem);
}

static enum print_line_t
print_graph_irq(struct trace_iterator *iter, unsigned long addr,
        enum trace_type type, int cpu, pid_t pid, u32 flags)
{
    int ret;
    struct trace_seq *s = &iter->seq;

    if (addr < (unsigned long)__irqentry_text_start ||
        addr >= (unsigned long)__irqentry_text_end)
        return TRACE_TYPE_UNHANDLED;

    if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
        /* Absolute time */
        if (flags & TRACE_GRAPH_PRINT_ABS_TIME) {
            ret = print_graph_abs_time(iter->ts, s);
            if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;
        }

        /* Cpu */
        if (flags & TRACE_GRAPH_PRINT_CPU) {
            ret = print_graph_cpu(s, cpu);
            if (ret == TRACE_TYPE_PARTIAL_LINE)
                return TRACE_TYPE_PARTIAL_LINE;
        }

        /* Proc */
        if (flags & TRACE_GRAPH_PRINT_PROC) {
            ret = print_graph_proc(s, pid);
            if (ret == TRACE_TYPE_PARTIAL_LINE)
                return TRACE_TYPE_PARTIAL_LINE;
            ret = trace_seq_printf(s, " | ");
            if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;
        }
    }

    /* No overhead */
    ret = print_graph_duration(DURATION_FILL_START, s, flags);
    if (ret != TRACE_TYPE_HANDLED)
        return ret;

    if (type == TRACE_GRAPH_ENT)
        ret = trace_seq_printf(s, "==========>");
    else
        ret = trace_seq_printf(s, "<==========");

    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    ret = print_graph_duration(DURATION_FILL_END, s, flags);
    if (ret != TRACE_TYPE_HANDLED)
        return ret;

    ret = trace_seq_printf(s, "\n");

    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;
    return TRACE_TYPE_HANDLED;
}

enum print_line_t
trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
{
    unsigned long nsecs_rem = do_div(duration, 1000);
    /* log10(ULONG_MAX) + '\0' */
    char msecs_str[21];
    char nsecs_str[5];
    int ret, len;
    int i;

    sprintf(msecs_str, "%lu", (unsigned long) duration);

    /* Print msecs */
    ret = trace_seq_printf(s, "%s", msecs_str);
    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    len = strlen(msecs_str);

    /* Print nsecs (we don't want to exceed 7 numbers) */
    if (len < 7) {
        size_t slen = min_t(size_t, sizeof(nsecs_str), 8UL - len);

        snprintf(nsecs_str, slen, "%03lu", nsecs_rem);
        ret = trace_seq_printf(s, ".%s", nsecs_str);
        if (!ret)
            return TRACE_TYPE_PARTIAL_LINE;
        len += strlen(nsecs_str);
    }

    ret = trace_seq_printf(s, " us ");
    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    /* Print remaining spaces to fit the row's width */
    for (i = len; i < 7; i++) {
        ret = trace_seq_printf(s, " ");
        if (!ret)
            return TRACE_TYPE_PARTIAL_LINE;
    }
    return TRACE_TYPE_HANDLED;
}

static enum print_line_t
print_graph_duration(unsigned long long duration, struct trace_seq *s,
             u32 flags)
{
    int ret = -1;

    if (!(flags & TRACE_GRAPH_PRINT_DURATION) ||
        !(trace_flags & TRACE_ITER_CONTEXT_INFO))
            return TRACE_TYPE_HANDLED;

    /* No real adata, just filling the column with spaces */
    switch (duration) {
    case DURATION_FILL_FULL:
        ret = trace_seq_printf(s, "              |  ");
        return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
    case DURATION_FILL_START:
        ret = trace_seq_printf(s, "  ");
        return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
    case DURATION_FILL_END:
        ret = trace_seq_printf(s, " |");
        return ret ? TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
    }

    /* Signal a overhead of time execution to the output */
    if (flags & TRACE_GRAPH_PRINT_OVERHEAD) {
        /* Duration exceeded 100 msecs */
        if (duration > 100000ULL)
            ret = trace_seq_printf(s, "! ");
        /* Duration exceeded 10 msecs */
        else if (duration > 10000ULL)
            ret = trace_seq_printf(s, "+ ");
    }

    /*
     * The -1 means we either did not exceed the duration tresholds
     * or we dont want to print out the overhead. Either way we need
     * to fill out the space.
     */
    if (ret == -1)
        ret = trace_seq_printf(s, "  ");

    /* Catching here any failure happenned above */
    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    ret = trace_print_graph_duration(duration, s);
    if (ret != TRACE_TYPE_HANDLED)
        return ret;

    ret = trace_seq_printf(s, "|  ");
    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    return TRACE_TYPE_HANDLED;
}

/* Case of a leaf function on its call entry */
static enum print_line_t
print_graph_entry_leaf(struct trace_iterator *iter,
        struct ftrace_graph_ent_entry *entry,
        struct ftrace_graph_ret_entry *ret_entry,
        struct trace_seq *s, u32 flags)
{
    struct fgraph_data *data = iter->private;
    struct ftrace_graph_ret *graph_ret;
    struct ftrace_graph_ent *call;
    unsigned long long duration;
    int ret;
    int i;

    graph_ret = &ret_entry->ret;
    call = &entry->graph_ent;
    duration = graph_ret->rettime - graph_ret->calltime;

    if (data) {
        struct fgraph_cpu_data *cpu_data;
        int cpu = iter->cpu;

        cpu_data = per_cpu_ptr(data->cpu_data, cpu);

        /*
         * Comments display at + 1 to depth. Since
         * this is a leaf function, keep the comments
         * equal to this depth.
         */
        cpu_data->depth = call->depth - 1;

        /* No need to keep this function around for this depth */
        if (call->depth < FTRACE_RETFUNC_DEPTH)
            cpu_data->enter_funcs[call->depth] = 0;
    }

    /* Overhead and duration */
    ret = print_graph_duration(duration, s, flags);
    if (ret == TRACE_TYPE_PARTIAL_LINE)
        return TRACE_TYPE_PARTIAL_LINE;

    /* Function */
    for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
        ret = trace_seq_printf(s, " ");
        if (!ret)
            return TRACE_TYPE_PARTIAL_LINE;
    }

    ret = trace_seq_printf(s, "%ps();\n", (void *)call->func);
    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    return TRACE_TYPE_HANDLED;
}

static enum print_line_t
print_graph_entry_nested(struct trace_iterator *iter,
             struct ftrace_graph_ent_entry *entry,
             struct trace_seq *s, int cpu, u32 flags)
{
    struct ftrace_graph_ent *call = &entry->graph_ent;
    struct fgraph_data *data = iter->private;
    int ret;
    int i;

    if (data) {
        struct fgraph_cpu_data *cpu_data;
        int cpu = iter->cpu;

        cpu_data = per_cpu_ptr(data->cpu_data, cpu);
        cpu_data->depth = call->depth;

        /* Save this function pointer to see if the exit matches */
        if (call->depth < FTRACE_RETFUNC_DEPTH)
            cpu_data->enter_funcs[call->depth] = call->func;
    }

    /* No time */
    ret = print_graph_duration(DURATION_FILL_FULL, s, flags);
    if (ret != TRACE_TYPE_HANDLED)
        return ret;

    /* Function */
    for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) {
        ret = trace_seq_printf(s, " ");
        if (!ret)
            return TRACE_TYPE_PARTIAL_LINE;
    }

    ret = trace_seq_printf(s, "%ps() {\n", (void *)call->func);
    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    /*
     * we already consumed the current entry to check the next one
     * and see if this is a leaf.
     */
    return TRACE_TYPE_NO_CONSUME;
}

static enum print_line_t
print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s,
             int type, unsigned long addr, u32 flags)
{
    struct fgraph_data *data = iter->private;
    struct trace_entry *ent = iter->ent;
    int cpu = iter->cpu;
    int ret;

    /* Pid */
    if (verif_pid(s, ent->pid, cpu, data) == TRACE_TYPE_PARTIAL_LINE)
        return TRACE_TYPE_PARTIAL_LINE;

    if (type) {
        /* Interrupt */
        ret = print_graph_irq(iter, addr, type, cpu, ent->pid, flags);
        if (ret == TRACE_TYPE_PARTIAL_LINE)
            return TRACE_TYPE_PARTIAL_LINE;
    }

    if (!(trace_flags & TRACE_ITER_CONTEXT_INFO))
        return 0;

    /* Absolute time */
    if (flags & TRACE_GRAPH_PRINT_ABS_TIME) {
        ret = print_graph_abs_time(iter->ts, s);
        if (!ret)
            return TRACE_TYPE_PARTIAL_LINE;
    }

    /* Cpu */
    if (flags & TRACE_GRAPH_PRINT_CPU) {
        ret = print_graph_cpu(s, cpu);
        if (ret == TRACE_TYPE_PARTIAL_LINE)
            return TRACE_TYPE_PARTIAL_LINE;
    }

    /* Proc */
    if (flags & TRACE_GRAPH_PRINT_PROC) {
        ret = print_graph_proc(s, ent->pid);
        if (ret == TRACE_TYPE_PARTIAL_LINE)
            return TRACE_TYPE_PARTIAL_LINE;

        ret = trace_seq_printf(s, " | ");
        if (!ret)
            return TRACE_TYPE_PARTIAL_LINE;
    }

    /* Latency format */
    if (trace_flags & TRACE_ITER_LATENCY_FMT) {
        ret = print_graph_lat_fmt(s, ent);
        if (ret == TRACE_TYPE_PARTIAL_LINE)
            return TRACE_TYPE_PARTIAL_LINE;
    }

    return 0;
}

/*
 * Entry check for irq code
 *
 * returns 1 if
 *  - we are inside irq code
 *  - we just entered irq code
 *
 * retunns 0 if
 *  - funcgraph-interrupts option is set
 *  - we are not inside irq code
 */
static int
check_irq_entry(struct trace_iterator *iter, u32 flags,
        unsigned long addr, int depth)
{
    int cpu = iter->cpu;
    int *depth_irq;
    struct fgraph_data *data = iter->private;

    /*
     * If we are either displaying irqs, or we got called as
     * a graph event and private data does not exist,
     * then we bypass the irq check.
     */
    if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
        (!data))
        return 0;

    depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);

    /*
     * We are inside the irq code
     */
    if (*depth_irq >= 0)
        return 1;

    if ((addr < (unsigned long)__irqentry_text_start) ||
        (addr >= (unsigned long)__irqentry_text_end))
        return 0;

    /*
     * We are entering irq code.
     */
    *depth_irq = depth;
    return 1;
}

/*
 * Return check for irq code
 *
 * returns 1 if
 *  - we are inside irq code
 *  - we just left irq code
 *
 * returns 0 if
 *  - funcgraph-interrupts option is set
 *  - we are not inside irq code
 */
static int
check_irq_return(struct trace_iterator *iter, u32 flags, int depth)
{
    int cpu = iter->cpu;
    int *depth_irq;
    struct fgraph_data *data = iter->private;

    /*
     * If we are either displaying irqs, or we got called as
     * a graph event and private data does not exist,
     * then we bypass the irq check.
     */
    if ((flags & TRACE_GRAPH_PRINT_IRQS) ||
        (!data))
        return 0;

    depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);

    /*
     * We are not inside the irq code.
     */
    if (*depth_irq == -1)
        return 0;

    /*
     * We are inside the irq code, and this is returning entry.
     * Let's not trace it and clear the entry depth, since
     * we are out of irq code.
     *
     * This condition ensures that we 'leave the irq code' once
     * we are out of the entry depth. Thus protecting us from
     * the RETURN entry loss.
     */
    if (*depth_irq >= depth) {
        *depth_irq = -1;
        return 1;
    }

    /*
     * We are inside the irq code, and this is not the entry.
     */
    return 1;
}

static enum print_line_t
print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s,
            struct trace_iterator *iter, u32 flags)
{
    struct fgraph_data *data = iter->private;
    struct ftrace_graph_ent *call = &field->graph_ent;
    struct ftrace_graph_ret_entry *leaf_ret;
    static enum print_line_t ret;
    int cpu = iter->cpu;

    if (check_irq_entry(iter, flags, call->func, call->depth))
        return TRACE_TYPE_HANDLED;

    if (print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func, flags))
        return TRACE_TYPE_PARTIAL_LINE;

    leaf_ret = get_return_for_leaf(iter, field);
    if (leaf_ret)
        ret = print_graph_entry_leaf(iter, field, leaf_ret, s, flags);
    else
        ret = print_graph_entry_nested(iter, field, s, cpu, flags);

    if (data) {
        /*
         * If we failed to write our output, then we need to make
         * note of it. Because we already consumed our entry.
         */
        if (s->full) {
            data->failed = 1;
            data->cpu = cpu;
        } else
            data->failed = 0;
    }

    return ret;
}

static enum print_line_t
print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s,
           struct trace_entry *ent, struct trace_iterator *iter,
           u32 flags)
{
    unsigned long long duration = trace->rettime - trace->calltime;
    struct fgraph_data *data = iter->private;
    pid_t pid = ent->pid;
    int cpu = iter->cpu;
    int func_match = 1;
    int ret;
    int i;

    if (check_irq_return(iter, flags, trace->depth))
        return TRACE_TYPE_HANDLED;

    if (data) {
        struct fgraph_cpu_data *cpu_data;
        int cpu = iter->cpu;

        cpu_data = per_cpu_ptr(data->cpu_data, cpu);

        /*
         * Comments display at + 1 to depth. This is the
         * return from a function, we now want the comments
         * to display at the same level of the bracket.
         */
        cpu_data->depth = trace->depth - 1;

        if (trace->depth < FTRACE_RETFUNC_DEPTH) {
            if (cpu_data->enter_funcs[trace->depth] != trace->func)
                func_match = 0;
            cpu_data->enter_funcs[trace->depth] = 0;
        }
    }

    if (print_graph_prologue(iter, s, 0, 0, flags))
        return TRACE_TYPE_PARTIAL_LINE;

    /* Overhead and duration */
    ret = print_graph_duration(duration, s, flags);
    if (ret == TRACE_TYPE_PARTIAL_LINE)
        return TRACE_TYPE_PARTIAL_LINE;

    /* Closing brace */
    for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) {
        ret = trace_seq_printf(s, " ");
        if (!ret)
            return TRACE_TYPE_PARTIAL_LINE;
    }

    /*
     * If the return function does not have a matching entry,
     * then the entry was lost. Instead of just printing
     * the '}' and letting the user guess what function this
     * belongs to, write out the function name.
     */
    if (func_match) {
        ret = trace_seq_printf(s, "}\n");
        if (!ret)
            return TRACE_TYPE_PARTIAL_LINE;
    } else {
        ret = trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func);
        if (!ret)
            return TRACE_TYPE_PARTIAL_LINE;
    }

    /* Overrun */
    if (flags & TRACE_GRAPH_PRINT_OVERRUN) {
        ret = trace_seq_printf(s, " (Overruns: %lu)\n",
                    trace->overrun);
        if (!ret)
            return TRACE_TYPE_PARTIAL_LINE;
    }

    ret = print_graph_irq(iter, trace->func, TRACE_GRAPH_RET,
                  cpu, pid, flags);
    if (ret == TRACE_TYPE_PARTIAL_LINE)
        return TRACE_TYPE_PARTIAL_LINE;

    return TRACE_TYPE_HANDLED;
}

static enum print_line_t
print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
            struct trace_iterator *iter, u32 flags)
{
    unsigned long sym_flags = (trace_flags & TRACE_ITER_SYM_MASK);
    struct fgraph_data *data = iter->private;
    struct trace_event *event;
    int depth = 0;
    int ret;
    int i;

    if (data)
        depth = per_cpu_ptr(data->cpu_data, iter->cpu)->depth;

    if (print_graph_prologue(iter, s, 0, 0, flags))
        return TRACE_TYPE_PARTIAL_LINE;

    /* No time */
    ret = print_graph_duration(DURATION_FILL_FULL, s, flags);
    if (ret != TRACE_TYPE_HANDLED)
        return ret;

    /* Indentation */
    if (depth > 0)
        for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++) {
            ret = trace_seq_printf(s, " ");
            if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;
        }

    /* The comment */
    ret = trace_seq_printf(s, "/* ");
    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    switch (iter->ent->type) {
    case TRACE_BPRINT:
        ret = trace_print_bprintk_msg_only(iter);
        if (ret != TRACE_TYPE_HANDLED)
            return ret;
        break;
    case TRACE_PRINT:
        ret = trace_print_printk_msg_only(iter);
        if (ret != TRACE_TYPE_HANDLED)
            return ret;
        break;
    default:
        event = ftrace_find_event(ent->type);
        if (!event)
            return TRACE_TYPE_UNHANDLED;

        ret = event->funcs->trace(iter, sym_flags, event);
        if (ret != TRACE_TYPE_HANDLED)
            return ret;
    }

    /* Strip ending newline */
    if (s->buffer[s->len - 1] == '\n') {
        s->buffer[s->len - 1] = '\0';
        s->len--;
    }

    ret = trace_seq_printf(s, " */\n");
    if (!ret)
        return TRACE_TYPE_PARTIAL_LINE;

    return TRACE_TYPE_HANDLED;
}


enum print_line_t
print_graph_function_flags(struct trace_iterator *iter, u32 flags)
{
    struct ftrace_graph_ent_entry *field;
    struct fgraph_data *data = iter->private;
    struct trace_entry *entry = iter->ent;
    struct trace_seq *s = &iter->seq;
    int cpu = iter->cpu;
    int ret;

    if (data && per_cpu_ptr(data->cpu_data, cpu)->ignore) {
        per_cpu_ptr(data->cpu_data, cpu)->ignore = 0;
        return TRACE_TYPE_HANDLED;
    }

    /*
     * If the last output failed, there's a possibility we need
     * to print out the missing entry which would never go out.
     */
    if (data && data->failed) {
        field = &data->ent;
        iter->cpu = data->cpu;
        ret = print_graph_entry(field, s, iter, flags);
        if (ret == TRACE_TYPE_HANDLED && iter->cpu != cpu) {
            per_cpu_ptr(data->cpu_data, iter->cpu)->ignore = 1;
            ret = TRACE_TYPE_NO_CONSUME;
        }
        iter->cpu = cpu;
        return ret;
    }

    switch (entry->type) {
    case TRACE_GRAPH_ENT: {
        /*
         * print_graph_entry() may consume the current event,
         * thus @field may become invalid, so we need to save it.
         * sizeof(struct ftrace_graph_ent_entry) is very small,
         * it can be safely saved at the stack.
         */
        struct ftrace_graph_ent_entry saved;
        trace_assign_type(field, entry);
        saved = *field;
        return print_graph_entry(&saved, s, iter, flags);
    }
    case TRACE_GRAPH_RET: {
        struct ftrace_graph_ret_entry *field;
        trace_assign_type(field, entry);
        return print_graph_return(&field->ret, s, entry, iter, flags);
    }
    case TRACE_STACK:
    case TRACE_FN:
        /* dont trace stack and functions as comments */
        return TRACE_TYPE_UNHANDLED;

    default:
        return print_graph_comment(s, entry, iter, flags);
    }

    return TRACE_TYPE_HANDLED;
}

static enum print_line_t
print_graph_function(struct trace_iterator *iter)
{
    return print_graph_function_flags(iter, tracer_flags.val);
}

static enum print_line_t
print_graph_function_event(struct trace_iterator *iter, int flags,
               struct trace_event *event)
{
    return print_graph_function(iter);
}

static void print_lat_header(struct seq_file *s, u32 flags)
{
    static const char spaces[] = "                " /* 16 spaces */
        "    "                  /* 4 spaces */
        "                 ";            /* 17 spaces */
    int size = 0;

    if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
        size += 16;
    if (flags & TRACE_GRAPH_PRINT_CPU)
        size += 4;
    if (flags & TRACE_GRAPH_PRINT_PROC)
        size += 17;

    seq_printf(s, "#%.*s  _-----=> irqs-off        \n", size, spaces);
    seq_printf(s, "#%.*s / _----=> need-resched    \n", size, spaces);
    seq_printf(s, "#%.*s| / _---=> hardirq/softirq \n", size, spaces);
    seq_printf(s, "#%.*s|| / _--=> preempt-depth   \n", size, spaces);
    seq_printf(s, "#%.*s||| /                      \n", size, spaces);
}

static void __print_graph_headers_flags(struct seq_file *s, u32 flags)
{
    int lat = trace_flags & TRACE_ITER_LATENCY_FMT;

    if (lat)
        print_lat_header(s, flags);

    /* 1st line */
    seq_printf(s, "#");
    if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
        seq_printf(s, "     TIME       ");
    if (flags & TRACE_GRAPH_PRINT_CPU)
        seq_printf(s, " CPU");
    if (flags & TRACE_GRAPH_PRINT_PROC)
        seq_printf(s, "  TASK/PID       ");
    if (lat)
        seq_printf(s, "||||");
    if (flags & TRACE_GRAPH_PRINT_DURATION)
        seq_printf(s, "  DURATION   ");
    seq_printf(s, "               FUNCTION CALLS\n");

    /* 2nd line */
    seq_printf(s, "#");
    if (flags & TRACE_GRAPH_PRINT_ABS_TIME)
        seq_printf(s, "      |         ");
    if (flags & TRACE_GRAPH_PRINT_CPU)
        seq_printf(s, " |  ");
    if (flags & TRACE_GRAPH_PRINT_PROC)
        seq_printf(s, "   |    |        ");
    if (lat)
        seq_printf(s, "||||");
    if (flags & TRACE_GRAPH_PRINT_DURATION)
        seq_printf(s, "   |   |      ");
    seq_printf(s, "               |   |   |   |\n");
}

void print_graph_headers(struct seq_file *s)
{
    print_graph_headers_flags(s, tracer_flags.val);
}

void print_graph_headers_flags(struct seq_file *s, u32 flags)
{
    struct trace_iterator *iter = s->private;

    if (!(trace_flags & TRACE_ITER_CONTEXT_INFO))
        return;

    if (trace_flags & TRACE_ITER_LATENCY_FMT) {
        /* print nothing if the buffers are empty */
        if (trace_empty(iter))
            return;

        print_trace_header(s, iter);
    }

    __print_graph_headers_flags(s, flags);
}

void graph_trace_open(struct trace_iterator *iter)
{
    /* pid and depth on the last trace processed */
    struct fgraph_data *data;
    int cpu;

    iter->private = NULL;

    data = kzalloc(sizeof(*data), GFP_KERNEL);
    if (!data)
        goto out_err;

    data->cpu_data = alloc_percpu(struct fgraph_cpu_data);
    if (!data->cpu_data)
        goto out_err_free;

    for_each_possible_cpu(cpu) {
        pid_t *pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid);
        int *depth = &(per_cpu_ptr(data->cpu_data, cpu)->depth);
        int *ignore = &(per_cpu_ptr(data->cpu_data, cpu)->ignore);
        int *depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq);

        *pid = -1;
        *depth = 0;
        *ignore = 0;
        *depth_irq = -1;
    }

    iter->private = data;

    return;

 out_err_free:
    kfree(data);
 out_err:
    pr_warning("function graph tracer: not enough memory\n");
}

void graph_trace_close(struct trace_iterator *iter)
{
    struct fgraph_data *data = iter->private;

    if (data) {
        free_percpu(data->cpu_data);
        kfree(data);
    }
}

static int func_graph_set_flag(u32 old_flags, u32 bit, int set)
{
    if (bit == TRACE_GRAPH_PRINT_IRQS)
        ftrace_graph_skip_irqs = !set;

    return 0;
}

static struct trace_event_functions graph_functions = {
    .trace      = print_graph_function_event,
};

static struct trace_event graph_trace_entry_event = {
    .type       = TRACE_GRAPH_ENT,
    .funcs      = &graph_functions,
};

static struct trace_event graph_trace_ret_event = {
    .type       = TRACE_GRAPH_RET,
    .funcs      = &graph_functions
};

static struct tracer graph_trace __read_mostly = {
    .name       = "function_graph",
    .open       = graph_trace_open,
    .pipe_open  = graph_trace_open,
    .close      = graph_trace_close,
    .pipe_close = graph_trace_close,
    .wait_pipe  = poll_wait_pipe,
    .init       = graph_trace_init,
    .reset      = graph_trace_reset,
    .print_line = print_graph_function,
    .print_header   = print_graph_headers,
    .flags      = &tracer_flags,
    .set_flag   = func_graph_set_flag,
#ifdef CONFIG_FTRACE_SELFTEST
    .selftest   = trace_selftest_startup_function_graph,
#endif
};

static __init int init_graph_trace(void)
{
    max_bytes_for_cpu = snprintf(NULL, 0, "%d", nr_cpu_ids - 1);

    if (!register_ftrace_event(&graph_trace_entry_event)) {
        pr_warning("Warning: could not register graph trace events\n");
        return 1;
    }

    if (!register_ftrace_event(&graph_trace_ret_event)) {
        pr_warning("Warning: could not register graph trace events\n");
        return 1;
    }

    return register_tracer(&graph_trace);
}

device_initcall(init_graph_trace);