1 files changed, 113 insertions, 3 deletions

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 757005458366..d35a7ee7611f 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -31,8 +31,8 @@ struct tracepoint {
 					 * Keep in sync with vmlinux.lds.h.
 					 */
 
-#define TPPROTO(args...)	args
-#define TPARGS(args...)		args
+#define TP_PROTO(args...)	args
+#define TP_ARGS(args...)		args
 
 #ifdef CONFIG_TRACEPOINTS
 
@@ -65,7 +65,7 @@ struct tracepoint {
 	{								\
 		if (unlikely(__tracepoint_##name.state))		\
 			__DO_TRACE(&__tracepoint_##name,		\
-				TPPROTO(proto), TPARGS(args));		\
+				TP_PROTO(proto), TP_ARGS(args));	\
 	}								\
 	static inline int register_trace_##name(void (*probe)(proto))	\
 	{								\
@@ -153,4 +153,114 @@ 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