/*
 * ring buffer based function tracer
 *
 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
 *
 * Based on code from the latency_tracer, that is:
 *
 *  Copyright (C) 2004-2006 Ingo Molnar
 *  Copyright (C) 2004 William Lee Irwin III
 */
#include <linux/ring_buffer.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/pstore.h>
#include <linux/fs.h>

#include "trace.h"

/* function tracing enabled */
static int                      ftrace_function_enabled;

static struct trace_array       *func_trace;

static void tracing_start_function_trace(void);
static void tracing_stop_function_trace(void);

static int function_trace_init(struct trace_array *tr)
{
        func_trace = tr;
        tr->cpu = get_cpu();
        put_cpu();

        tracing_start_cmdline_record();
        tracing_start_function_trace();
        return 0;
}

static void function_trace_reset(struct trace_array *tr)
{
        tracing_stop_function_trace();
        tracing_stop_cmdline_record();
}

static void function_trace_start(struct trace_array *tr)
{
        tracing_reset_online_cpus(tr);
}

static void
function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
{
        struct trace_array *tr = func_trace;
        struct trace_array_cpu *data;
        unsigned long flags;
        long disabled;
        int cpu;
        int pc;

        if (unlikely(!ftrace_function_enabled))
                return;

        pc = preempt_count();
        preempt_disable_notrace();
        local_save_flags(flags);
        cpu = raw_smp_processor_id();
        data = tr->data[cpu];
        disabled = atomic_inc_return(&data->disabled);

        if (likely(disabled == 1))
                trace_function(tr, ip, parent_ip, flags, pc);

        atomic_dec(&data->disabled);
        preempt_enable_notrace();
}

/* Our two options */
enum {
        TRACE_FUNC_OPT_STACK    = 0x1,
        TRACE_FUNC_OPT_PSTORE   = 0x2,
};

static struct tracer_flags func_flags;

static void
function_trace_call(unsigned long ip, unsigned long parent_ip)
{
        struct trace_array *tr = func_trace;
        struct trace_array_cpu *data;
        unsigned long flags;
        long disabled;
        int cpu;
        int pc;

        if (unlikely(!ftrace_function_enabled))
                return;

        /*
         * Need to use raw, since this must be called before the
         * recursive protection is performed.
         */
        local_irq_save(flags);
        cpu = raw_smp_processor_id();
        data = tr->data[cpu];
        disabled = atomic_inc_return(&data->disabled);

        if (likely(disabled == 1)) {
                /*
                 * So far tracing doesn't support multiple buffers, so
                 * we make an explicit call for now.
                 */
                if (unlikely(func_flags.val & TRACE_FUNC_OPT_PSTORE))
                        pstore_ftrace_call(ip, parent_ip);
                pc = preempt_count();
                trace_function(tr, ip, parent_ip, flags, pc);
        }

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

static void
function_stack_trace_call(unsigned long ip, unsigned long parent_ip)
{
        struct trace_array *tr = func_trace;
        struct trace_array_cpu *data;
        unsigned long flags;
        long disabled;
        int cpu;
        int pc;

        if (unlikely(!ftrace_function_enabled))
                return;

        /*
         * Need to use raw, since this must be called before the
         * recursive protection is performed.
         */
        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_function(tr, ip, parent_ip, flags, pc);
                /*
                 * skip over 5 funcs:
                 *    __ftrace_trace_stack,
                 *    __trace_stack,
                 *    function_stack_trace_call
                 *    ftrace_list_func
                 *    ftrace_call
                 */
                __trace_stack(tr, flags, 5, pc);
        }

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


static struct ftrace_ops trace_ops __read_mostly =
{
        .func = function_trace_call,
        .flags = FTRACE_OPS_FL_GLOBAL,
};

static struct ftrace_ops trace_stack_ops __read_mostly =
{
        .func = function_stack_trace_call,
        .flags = FTRACE_OPS_FL_GLOBAL,
};

static struct tracer_opt func_opts[] = {
#ifdef CONFIG_STACKTRACE
        { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
#endif
#ifdef CONFIG_PSTORE_FTRACE
        { TRACER_OPT(func_pstore, TRACE_FUNC_OPT_PSTORE) },
#endif
        { } /* Always set a last empty entry */
};

static struct tracer_flags func_flags = {
        .val = 0, /* By default: all flags disabled */
        .opts = func_opts
};

static void tracing_start_function_trace(void)
{
        ftrace_function_enabled = 0;

        if (trace_flags & TRACE_ITER_PREEMPTONLY)
                trace_ops.func = function_trace_call_preempt_only;
        else
                trace_ops.func = function_trace_call;

        if (func_flags.val & TRACE_FUNC_OPT_STACK)
                register_ftrace_function(&trace_stack_ops);
        else
                register_ftrace_function(&trace_ops);

        ftrace_function_enabled = 1;
}

static void tracing_stop_function_trace(void)
{
        ftrace_function_enabled = 0;

        if (func_flags.val & TRACE_FUNC_OPT_STACK)
                unregister_ftrace_function(&trace_stack_ops);
        else
                unregister_ftrace_function(&trace_ops);
}

static int func_set_flag(u32 old_flags, u32 bit, int set)
{
        switch (bit) {
        case TRACE_FUNC_OPT_STACK:
                /* do nothing if already set */
                if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK))
                        break;

                if (set) {
                        unregister_ftrace_function(&trace_ops);
                        register_ftrace_function(&trace_stack_ops);
                } else {
                        unregister_ftrace_function(&trace_stack_ops);
                        register_ftrace_function(&trace_ops);
                }

                break;
        case TRACE_FUNC_OPT_PSTORE:
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static struct tracer function_trace __read_mostly =
{
        .name           = "function",
        .init           = function_trace_init,
        .reset          = function_trace_reset,
        .start          = function_trace_start,
        .wait_pipe      = poll_wait_pipe,
        .flags          = &func_flags,
        .set_flag       = func_set_flag,
#ifdef CONFIG_FTRACE_SELFTEST
        .selftest       = trace_selftest_startup_function,
#endif
};

#ifdef CONFIG_DYNAMIC_FTRACE
static void
ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
{
        long *count = (long *)data;

        if (tracing_is_on())
                return;

        if (!*count)
                return;

        if (*count != -1)
                (*count)--;

        tracing_on();
}

static void
ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
{
        long *count = (long *)data;

        if (!tracing_is_on())
                return;

        if (!*count)
                return;

        if (*count != -1)
                (*count)--;

        tracing_off();
}

static int
ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
                         struct ftrace_probe_ops *ops, void *data);

static struct ftrace_probe_ops traceon_probe_ops = {
        .func                   = ftrace_traceon,
        .print                  = ftrace_trace_onoff_print,
};

static struct ftrace_probe_ops traceoff_probe_ops = {
        .func                   = ftrace_traceoff,
        .print                  = ftrace_trace_onoff_print,
};

static int
ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip,
                         struct ftrace_probe_ops *ops, void *data)
{
        long count = (long)data;

        seq_printf(m, "%ps:", (void *)ip);

        if (ops == &traceon_probe_ops)
                seq_printf(m, "traceon");
        else
                seq_printf(m, "traceoff");

        if (count == -1)
                seq_printf(m, ":unlimited\n");
        else
                seq_printf(m, ":count=%ld\n", count);

        return 0;
}

static int
ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
{
        struct ftrace_probe_ops *ops;

        /* we register both traceon and traceoff to this callback */
        if (strcmp(cmd, "traceon") == 0)
                ops = &traceon_probe_ops;
        else
                ops = &traceoff_probe_ops;

        unregister_ftrace_function_probe_func(glob, ops);

        return 0;
}

static int
ftrace_trace_onoff_callback(struct ftrace_hash *hash,
                            char *glob, char *cmd, char *param, int enable)
{
        struct ftrace_probe_ops *ops;
        void *count = (void *)-1;
        char *number;
        int ret;

        /* hash funcs only work with set_ftrace_filter */
        if (!enable)
                return -EINVAL;

        if (glob[0] == '!')
                return ftrace_trace_onoff_unreg(glob+1, cmd, param);

        /* we register both traceon and traceoff to this callback */
        if (strcmp(cmd, "traceon") == 0)
                ops = &traceon_probe_ops;
        else
                ops = &traceoff_probe_ops;

        if (!param)
                goto out_reg;

        number = strsep(&param, ":");

        if (!strlen(number))
                goto out_reg;

        /*
         * We use the callback data field (which is a pointer)
         * as our counter.
         */
        ret = strict_strtoul(number, 0, (unsigned long *)&count);
        if (ret)
                return ret;

 out_reg:
        ret = register_ftrace_function_probe(glob, ops, count);

        return ret < 0 ? ret : 0;
}

static struct ftrace_func_command ftrace_traceon_cmd = {
        .name                   = "traceon",
        .func                   = ftrace_trace_onoff_callback,
};

static struct ftrace_func_command ftrace_traceoff_cmd = {
        .name                   = "traceoff",
        .func                   = ftrace_trace_onoff_callback,
};

static int __init init_func_cmd_traceon(void)
{
        int ret;

        ret = register_ftrace_command(&ftrace_traceoff_cmd);
        if (ret)
                return ret;

        ret = register_ftrace_command(&ftrace_traceon_cmd);
        if (ret)
                unregister_ftrace_command(&ftrace_traceoff_cmd);
        return ret;
}
#else
static inline int init_func_cmd_traceon(void)
{
        return 0;
}
#endif /* CONFIG_DYNAMIC_FTRACE */

static __init int init_function_trace(void)
{
        init_func_cmd_traceon();
        return register_tracer(&function_trace);
}
device_initcall(init_function_trace);