/*
 *
 * Function graph tracer.
 * Copyright (c) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
 * Mostly borrowed from function tracer which
 * is Copyright (c) Steven Rostedt <srostedt@redhat.com>
 *
 */
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/fs.h>

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

struct fgraph_data {
        pid_t           last_pid;
        int             depth;
};

#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

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) },
        { } /* 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,
        .opts = trace_opts
};

static struct trace_array *graph_array;


/* 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;
        }

#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST
        /*
         * 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.
         */
        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;
}

static 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(local_read(&__get_cpu_var(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;
}

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 (unlikely(!tr))
                return 0;

        if (!ftrace_trace_task(current))
                return 0;

        if (!ftrace_graph_addr(trace->func))
                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;
        }
        /* Only do the atomic if it is not already set */
        if (!test_tsk_trace_graph(current))
                set_tsk_trace_graph(current);

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

        return ret;
}

static 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(local_read(&__get_cpu_var(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);
        }
        if (!trace->depth)
                clear_tsk_trace_graph(current);
        atomic_dec(&data->disabled);
        local_irq_restore(flags);
}

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

        graph_array = tr;
        ret = register_ftrace_graph(&trace_graph_return,
                                    &trace_graph_entry);
        if (ret)
                return ret;
        tracing_start_cmdline_record();

        return 0;
}

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

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)->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 ring_buffer_iter *ring_iter;
        struct ring_buffer_event *event;
        struct ftrace_graph_ret_entry *next;

        ring_iter = iter->buffer_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);
                event = ring_buffer_peek(iter->tr->buffer, iter->cpu,
                                        NULL);
        }

        if (!event)
                return NULL;

        next = ring_buffer_event_data(event);

        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;
}

/* Signal a overhead of time execution to the output */
static int
print_graph_overhead(unsigned long long duration, struct trace_seq *s)
{
        /* If duration disappear, we don't need anything */
        if (!(tracer_flags.val & TRACE_GRAPH_PRINT_DURATION))
                return 1;

        /* Non nested entry or return */
        if (duration == -1)
                return trace_seq_printf(s, "  ");

        if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERHEAD) {
                /* Duration exceeded 100 msecs */
                if (duration > 100000ULL)
                        return trace_seq_printf(s, "! ");

                /* Duration exceeded 10 msecs */
                if (duration > 10000ULL)
                        return trace_seq_printf(s, "+ ");
        }

        return trace_seq_printf(s, "  ");
}

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)
{
        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;

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

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

        /* Proc */
        if (tracer_flags.val & 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_overhead(-1, s);
        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;

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

        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;

        /* Don't close the duration column if haven't one */
        if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION)
                trace_seq_printf(s, " |");
        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) {
                snprintf(nsecs_str, 8 - len, "%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)
{
        int ret;

        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)
{
        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) {
                int cpu = iter->cpu;
                int *depth = &(per_cpu_ptr(data, cpu)->depth);

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

        /* Overhead */
        ret = print_graph_overhead(duration, s);
        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;

        /* Duration */
        if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
                ret = print_graph_duration(duration, s);
                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)
{
        struct ftrace_graph_ent *call = &entry->graph_ent;
        struct fgraph_data *data = iter->private;
        int ret;
        int i;

        if (data) {
                int cpu = iter->cpu;
                int *depth = &(per_cpu_ptr(data, cpu)->depth);

                *depth = call->depth;
        }

        /* No overhead */
        ret = print_graph_overhead(-1, s);
        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;

        /* No time */
        if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
                ret = trace_seq_printf(s, "            |  ");
                if (!ret)
                        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;

        /*
         * 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)
{
        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);
                if (ret == TRACE_TYPE_PARTIAL_LINE)
                        return TRACE_TYPE_PARTIAL_LINE;
        }

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

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

        /* Proc */
        if (tracer_flags.val & 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;
}

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

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

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

}

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)
{
        unsigned long long duration = trace->rettime - trace->calltime;
        struct fgraph_data *data = iter->private;
        pid_t pid = ent->pid;
        int cpu = iter->cpu;
        int ret;
        int i;

        if (data) {
                int cpu = iter->cpu;
                int *depth = &(per_cpu_ptr(data, cpu)->depth);

                /*
                 * 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.
                 */
                *depth = trace->depth - 1;
        }

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

        /* Overhead */
        ret = print_graph_overhead(duration, s);
        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;

        /* Duration */
        if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
                ret = print_graph_duration(duration, s);
                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;
        }

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

        /* Overrun */
        if (tracer_flags.val & 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);
        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)
{
        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, iter->cpu)->depth;

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

        /* No overhead */
        ret = print_graph_overhead(-1, s);
        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;

        /* No time */
        if (tracer_flags.val & TRACE_GRAPH_PRINT_DURATION) {
                ret = trace_seq_printf(s, "            |  ");
                if (!ret)
                        return TRACE_TYPE_PARTIAL_LINE;
        }

        /* 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->trace(iter, sym_flags);
                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(struct trace_iterator *iter)
{
        struct trace_entry *entry = iter->ent;
        struct trace_seq *s = &iter->seq;

        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 *field, saved;
                trace_assign_type(field, entry);
                saved = *field;
                return print_graph_entry(&saved, s, iter);
        }
        case TRACE_GRAPH_RET: {
                struct ftrace_graph_ret_entry *field;
                trace_assign_type(field, entry);
                return print_graph_return(&field->ret, s, entry, iter);
        }
        default:
                return print_graph_comment(s, entry, iter);
        }

        return TRACE_TYPE_HANDLED;
}

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

        if (tracer_flags.val & TRACE_GRAPH_PRINT_ABS_TIME)
                size += 16;
        if (tracer_flags.val & TRACE_GRAPH_PRINT_CPU)
                size += 4;
        if (tracer_flags.val & 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||| / _-=> lock-depth      \n", size, spaces);
        seq_printf(s, "#%.*s|||| /                     \n", size, spaces);
}

static void print_graph_headers(struct seq_file *s)
{
        int lat = trace_flags & TRACE_ITER_LATENCY_FMT;

        if (lat)
                print_lat_header(s);

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

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

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

        if (!data)
                pr_warning("function graph tracer: not enough memory\n");
        else
                for_each_possible_cpu(cpu) {
                        pid_t *pid = &(per_cpu_ptr(data, cpu)->last_pid);
                        int *depth = &(per_cpu_ptr(data, cpu)->depth);
                        *pid = -1;
                        *depth = 0;
                }

        iter->private = data;
}

static void graph_trace_close(struct trace_iterator *iter)
{
        free_percpu(iter->private);
}

static struct tracer graph_trace __read_mostly = {
        .name           = "function_graph",
        .open           = graph_trace_open,
        .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,
#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);

        return register_tracer(&graph_trace);
}

device_initcall(init_graph_trace);