#ifndef _LINUX_TRACEPOINT_H
#define _LINUX_TRACEPOINT_H

/*
 * Kernel Tracepoint API.
 *
 * See Documentation/tracepoint.txt.
 *
 * (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
 *
 * Heavily inspired from the Linux Kernel Markers.
 *
 * This file is released under the GPLv2.
 * See the file COPYING for more details.
 */

#include <linux/types.h>
#include <linux/rcupdate.h>

struct module;
struct tracepoint;

struct tracepoint {
        const char *name;               /* Tracepoint name */
        int state;                      /* State. */
        void **funcs;
} __attribute__((aligned(32)));         /*
                                         * Aligned on 32 bytes because it is
                                         * globally visible and gcc happily
                                         * align these on the structure size.
                                         * Keep in sync with vmlinux.lds.h.
                                         */

#define TP_PROTO(args...)       args
#define TP_ARGS(args...)                args

#ifdef CONFIG_TRACEPOINTS

/*
 * it_func[0] is never NULL because there is at least one element in the array
 * when the array itself is non NULL.
 */
#define __DO_TRACE(tp, proto, args)                                     \
        do {                                                            \
                void **it_func;                                         \
                                                                        \
                rcu_read_lock_sched_notrace();                          \
                it_func = rcu_dereference((tp)->funcs);                 \
                if (it_func) {                                          \
                        do {                                            \
                                ((void(*)(proto))(*it_func))(args);     \
                        } while (*(++it_func));                         \
                }                                                       \
                rcu_read_unlock_sched_notrace();                        \
        } while (0)

/*
 * Make sure the alignment of the structure in the __tracepoints section will
 * not add unwanted padding between the beginning of the section and the
 * structure. Force alignment to the same alignment as the section start.
 */
#define DECLARE_TRACE(name, proto, args)                                \
        extern struct tracepoint __tracepoint_##name;                   \
        static inline void trace_##name(proto)                          \
        {                                                               \
                if (unlikely(__tracepoint_##name.state))                \
                        __DO_TRACE(&__tracepoint_##name,                \
                                TP_PROTO(proto), TP_ARGS(args));        \
        }                                                               \
        static inline int register_trace_##name(void (*probe)(proto))   \
        {                                                               \
                return tracepoint_probe_register(#name, (void *)probe); \
        }                                                               \
        static inline int unregister_trace_##name(void (*probe)(proto)) \
        {                                                               \
                return tracepoint_probe_unregister(#name, (void *)probe);\
        }

#define DEFINE_TRACE(name)                                              \
        static const char __tpstrtab_##name[]                           \
        __attribute__((section("__tracepoints_strings"))) = #name;      \
        struct tracepoint __tracepoint_##name                           \
        __attribute__((section("__tracepoints"), aligned(32))) =        \
                { __tpstrtab_##name, 0, NULL }

#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)                              \
        EXPORT_SYMBOL_GPL(__tracepoint_##name)
#define EXPORT_TRACEPOINT_SYMBOL(name)                                  \
        EXPORT_SYMBOL(__tracepoint_##name)

extern void tracepoint_update_probe_range(struct tracepoint *begin,
        struct tracepoint *end);

#else /* !CONFIG_TRACEPOINTS */
#define DECLARE_TRACE(name, proto, args)                                \
        static inline void _do_trace_##name(struct tracepoint *tp, proto) \
        { }                                                             \
        static inline void trace_##name(proto)                          \
        { }                                                             \
        static inline int register_trace_##name(void (*probe)(proto))   \
        {                                                               \
                return -ENOSYS;                                         \
        }                                                               \
        static inline int unregister_trace_##name(void (*probe)(proto)) \
        {                                                               \
                return -ENOSYS;                                         \
        }

#define DEFINE_TRACE(name)
#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
#define EXPORT_TRACEPOINT_SYMBOL(name)

static inline void tracepoint_update_probe_range(struct tracepoint *begin,
        struct tracepoint *end)
{ }
#endif /* CONFIG_TRACEPOINTS */

/*
 * Connect a probe to a tracepoint.
 * Internal API, should not be used directly.
 */
extern int tracepoint_probe_register(const char *name, void *probe);

/*
 * Disconnect a probe from a tracepoint.
 * Internal API, should not be used directly.
 */
extern int tracepoint_probe_unregister(const char *name, void *probe);

extern int tracepoint_probe_register_noupdate(const char *name, void *probe);
extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe);
extern void tracepoint_probe_update_all(void);

struct tracepoint_iter {
        struct module *module;
        struct tracepoint *tracepoint;
};

extern void tracepoint_iter_start(struct tracepoint_iter *iter);
extern void tracepoint_iter_next(struct tracepoint_iter *iter);
extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
extern int tracepoint_get_iter_range(struct tracepoint **tracepoint,
        struct tracepoint *begin, struct tracepoint *end);

/*
 * tracepoint_synchronize_unregister must be called between the last tracepoint
 * probe unregistration and the end of module exit to make sure there is no
 * caller executing a probe when it is freed.
 */
static inline void tracepoint_synchronize_unregister(void)
{
        synchronize_sched();
}

#define PARAMS(args...) args
#define TRACE_FORMAT(name, proto, args, fmt)            \
        DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))


/*
 * For use with the TRACE_EVENT macro:
 *
 * We define a tracepoint, its arguments, its printk format
 * and its 'fast binay record' layout.
 *
 * Firstly, name your tracepoint via TRACE_EVENT(name : the
 * 'subsystem_event' notation is fine.
 *
 * Think about this whole construct as the
 * 'trace_sched_switch() function' from now on.
 *
 *
 *  TRACE_EVENT(sched_switch,
 *
 *      *
 *      * A function has a regular function arguments
 *      * prototype, declare it via TP_PROTO():
 *      *
 *
 *      TP_PROTO(struct rq *rq, struct task_struct *prev,
 *               struct task_struct *next),
 *
 *      *
 *      * Define the call signature of the 'function'.
 *      * (Design sidenote: we use this instead of a
 *      *  TP_PROTO1/TP_PROTO2/TP_PROTO3 ugliness.)
 *      *
 *
 *      TP_ARGS(rq, prev, next),
 *
 *      *
 *      * Fast binary tracing: define the trace record via
 *      * TP_STRUCT__entry(). You can think about it like a
 *      * regular C structure local variable definition.
 *      *
 *      * This is how the trace record is structured and will
 *      * be saved into the ring buffer. These are the fields
 *      * that will be exposed to user-space in
 *      * /debug/tracing/events/<*>/format.
 *      *
 *      * The declared 'local variable' is called '__entry'
 *      *
 *      * __field(pid_t, prev_prid) is equivalent to a standard declariton:
 *      *
 *      *       pid_t   prev_pid;
 *      *
 *      * __array(char, prev_comm, TASK_COMM_LEN) is equivalent to:
 *      *
 *      *       char    prev_comm[TASK_COMM_LEN];
 *      *
 *
 *      TP_STRUCT__entry(
 *              __array(        char,   prev_comm,      TASK_COMM_LEN   )
 *              __field(        pid_t,  prev_pid                        )
 *              __field(        int,    prev_prio                       )
 *              __array(        char,   next_comm,      TASK_COMM_LEN   )
 *              __field(        pid_t,  next_pid                        )
 *              __field(        int,    next_prio                       )
 *      ),
 *
 *      *
 *      * Assign the entry into the trace record, by embedding
 *      * a full C statement block into TP_fast_assign(). You
 *      * can refer to the trace record as '__entry' -
 *      * otherwise you can put arbitrary C code in here.
 *      *
 *      * Note: this C code will execute every time a trace event
 *      * happens, on an active tracepoint.
 *      *
 *
 *      TP_fast_assign(
 *              memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
 *              __entry->prev_pid       = prev->pid;
 *              __entry->prev_prio      = prev->prio;
 *              memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
 *              __entry->next_pid       = next->pid;
 *              __entry->next_prio      = next->prio;
 *      )
 *
 *      *
 *      * Formatted output of a trace record via TP_printk().
 *      * This is how the tracepoint will appear under ftrace
 *      * plugins that make use of this tracepoint.
 *      *
 *      * (raw-binary tracing wont actually perform this step.)
 *      *
 *
 *      TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
 *              __entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
 *              __entry->next_comm, __entry->next_pid, __entry->next_prio),
 *
 * );
 *
 * This macro construct is thus used for the regular printk format
 * tracing setup, it is used to construct a function pointer based
 * tracepoint callback (this is used by programmatic plugins and
 * can also by used by generic instrumentation like SystemTap), and
 * it is also used to expose a structured trace record in
 * /debug/tracing/events/.
 */

#define TRACE_EVENT(name, proto, args, struct, assign, print)   \
        DECLARE_TRACE(name, PARAMS(proto), PARAMS(args))

#endif