tracing: Allow events to share their print functions

Multiple events may use the same method to print their data.
Instead of having all events have a pointer to their print funtions,
the trace_event structure now points to a trace_event_functions structure
that will hold the way to print ouf the event.

The event itself is now passed to the print function to let the print
function know what kind of event it should print.

This opens the door to consolidating the way several events print
their output.

   text	   data	    bss	    dec	    hex	filename
4913961	1088356	 861512	6863829	 68bbd5	vmlinux.orig
4900382	1048964	 861512	6810858	 67ecea	vmlinux.init
4900446	1049028	 861512	6810986	 67ed6a	vmlinux.preprint

This change slightly increases the size but is needed for the next change.

v3: Fix the branch tracer events to handle this change.

v2: Fix the new function graph tracer event calls to handle this change.
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

include/linux/ftrace_event.h

@@ -70,18 +70,25 @@ struct trace_iterator {
 };
 
 
+struct trace_event;
+
 typedef enum print_line_t (*trace_print_func)(struct trace_iterator *iter,
-					      int flags);
-struct trace_event {
-	struct hlist_node	node;
-	struct list_head	list;
-	int			type;
+				      int flags, struct trace_event *event);
+
+struct trace_event_functions {
 	trace_print_func	trace;
 	trace_print_func	raw;
 	trace_print_func	hex;
 	trace_print_func	binary;
 };
 
+struct trace_event {
+	struct hlist_node		node;
+	struct list_head		list;
+	int				type;
+	struct trace_event_functions	*funcs;
+};
+
 extern int register_ftrace_event(struct trace_event *event);
 extern int unregister_ftrace_event(struct trace_event *event);
 

include/linux/syscalls.h

@@ -125,9 +125,12 @@ extern struct ftrace_event_class event_class_syscall_exit;
 	static struct syscall_metadata __syscall_meta_##sname;		\
 	static struct ftrace_event_call					\
 	__attribute__((__aligned__(4))) event_enter_##sname;		\
-	static struct trace_event enter_syscall_print_##sname = {	\
+	static struct trace_event_functions enter_syscall_print_funcs_##sname = { \
 		.trace                  = print_syscall_enter,		\
 	};								\
+	static struct trace_event enter_syscall_print_##sname = {	\
+		.funcs                  = &enter_syscall_print_funcs_##sname, \
+	};								\
 	static struct ftrace_event_call __used				\
 	  __attribute__((__aligned__(4)))				\
 	  __attribute__((section("_ftrace_events")))			\
@@ -142,9 +145,12 @@ extern struct ftrace_event_class event_class_syscall_exit;
 	static struct syscall_metadata __syscall_meta_##sname;		\
 	static struct ftrace_event_call					\
 	__attribute__((__aligned__(4))) event_exit_##sname;		\
-	static struct trace_event exit_syscall_print_##sname = {	\
+	static struct trace_event_functions exit_syscall_print_funcs_##sname = { \
 		.trace                  = print_syscall_exit,		\
 	};								\
+	static struct trace_event exit_syscall_print_##sname = {	\
+		.funcs                  = &exit_syscall_print_funcs_##sname, \
+	};								\
 	static struct ftrace_event_call __used				\
 	  __attribute__((__aligned__(4)))				\
 	  __attribute__((section("_ftrace_events")))			\

include/trace/ftrace.h

@@ -239,7 +239,8 @@ ftrace_raw_output_id_##call(int event_id, const char *name,		\
 #undef DEFINE_EVENT
 #define DEFINE_EVENT(template, name, proto, args)			\
 static notrace enum print_line_t					\
-ftrace_raw_output_##name(struct trace_iterator *iter, int flags)	\
+ftrace_raw_output_##name(struct trace_iterator *iter, int flags,	\
+			 struct trace_event *event)			\
 {									\
 	return ftrace_raw_output_id_##template(event_##name.id,		\
 					       #name, iter, flags);	\
@@ -248,7 +249,8 @@ ftrace_raw_output_##name(struct trace_iterator *iter, int flags)	\
 #undef DEFINE_EVENT_PRINT
 #define DEFINE_EVENT_PRINT(template, call, proto, args, print)		\
 static notrace enum print_line_t					\
-ftrace_raw_output_##call(struct trace_iterator *iter, int flags)	\
+ftrace_raw_output_##call(struct trace_iterator *iter, int flags,	\
+			 struct trace_event *event)			\
 {									\
 	struct trace_seq *s = &iter->seq;				\
 	struct ftrace_raw_##template *field;				\
@@ -531,11 +533,12 @@ ftrace_raw_event_##call(void *__data, proto)				\
 
 #undef DEFINE_EVENT
 #define DEFINE_EVENT(template, call, proto, args)			\
-									\
-static struct trace_event ftrace_event_type_##call = {			\
+static struct trace_event_functions ftrace_event_type_funcs_##call = {	\
 	.trace			= ftrace_raw_output_##call,		\
 };									\
-									\
+static struct trace_event ftrace_event_type_##call = {			\
+	.funcs			= &ftrace_event_type_funcs_##call,	\
+};									\
 static inline void ftrace_test_probe_##call(void)			\
 {									\
 	check_trace_callback_type_##call(ftrace_raw_event_##template);	\

include/trace/syscall.h

@@ -42,8 +42,10 @@ extern int reg_event_syscall_exit(struct ftrace_event_call *call);
 extern void unreg_event_syscall_exit(struct ftrace_event_call *call);
 extern int
 ftrace_format_syscall(struct ftrace_event_call *call, struct trace_seq *s);
-enum print_line_t print_syscall_enter(struct trace_iterator *iter, int flags);
-enum print_line_t print_syscall_exit(struct trace_iterator *iter, int flags);
+enum print_line_t print_syscall_enter(struct trace_iterator *iter, int flags,
+				      struct trace_event *event);
+enum print_line_t print_syscall_exit(struct trace_iterator *iter, int flags,
+				     struct trace_event *event);
 #endif
 
 #ifdef CONFIG_PERF_EVENTS

kernel/trace/blktrace.c

@@ -1336,7 +1336,7 @@ static enum print_line_t print_one_line(struct trace_iterator *iter,
 }
 
 static enum print_line_t blk_trace_event_print(struct trace_iterator *iter,
-					       int flags)
+					       int flags, struct trace_event *event)
 {
 	return print_one_line(iter, false);
 }
@@ -1358,7 +1358,8 @@ static int blk_trace_synthesize_old_trace(struct trace_iterator *iter)
 }
 
 static enum print_line_t
-blk_trace_event_print_binary(struct trace_iterator *iter, int flags)
+blk_trace_event_print_binary(struct trace_iterator *iter, int flags,
+			     struct trace_event *event)
 {
 	return blk_trace_synthesize_old_trace(iter) ?
 			TRACE_TYPE_HANDLED : TRACE_TYPE_PARTIAL_LINE;
@@ -1396,12 +1397,16 @@ static struct tracer blk_tracer __read_mostly = {
 	.set_flag	= blk_tracer_set_flag,
 };
 
-static struct trace_event trace_blk_event = {
-	.type		= TRACE_BLK,
+static struct trace_event_functions trace_blk_event_funcs = {
 	.trace		= blk_trace_event_print,
 	.binary		= blk_trace_event_print_binary,
 };
 
+static struct trace_event trace_blk_event = {
+	.type		= TRACE_BLK,
+	.funcs		= &trace_blk_event_funcs,
+};
+
 static int __init init_blk_tracer(void)
 {
 	if (!register_ftrace_event(&trace_blk_event)) {

kernel/trace/kmemtrace.c

@@ -243,7 +243,8 @@ struct kmemtrace_user_event_alloc {
 };
 
 static enum print_line_t
-kmemtrace_print_alloc(struct trace_iterator *iter, int flags)
+kmemtrace_print_alloc(struct trace_iterator *iter, int flags,
+		      struct trace_event *event)
 {
 	struct trace_seq *s = &iter->seq;
 	struct kmemtrace_alloc_entry *entry;
@@ -263,7 +264,8 @@ kmemtrace_print_alloc(struct trace_iterator *iter, int flags)
 }
 
 static enum print_line_t
-kmemtrace_print_free(struct trace_iterator *iter, int flags)
+kmemtrace_print_free(struct trace_iterator *iter, int flags,
+		     struct trace_event *event)
 {
 	struct trace_seq *s = &iter->seq;
 	struct kmemtrace_free_entry *entry;
@@ -281,7 +283,8 @@ kmemtrace_print_free(struct trace_iterator *iter, int flags)
 }
 
 static enum print_line_t
-kmemtrace_print_alloc_user(struct trace_iterator *iter, int flags)
+kmemtrace_print_alloc_user(struct trace_iterator *iter, int flags,
+			   struct trace_event *event)
 {
 	struct trace_seq *s = &iter->seq;
 	struct kmemtrace_alloc_entry *entry;
@@ -315,7 +318,8 @@ kmemtrace_print_alloc_user(struct trace_iterator *iter, int flags)
 }
 
 static enum print_line_t
-kmemtrace_print_free_user(struct trace_iterator *iter, int flags)
+kmemtrace_print_free_user(struct trace_iterator *iter, int flags,
+			  struct trace_event *event)
 {
 	struct trace_seq *s = &iter->seq;
 	struct kmemtrace_free_entry *entry;
@@ -469,18 +473,26 @@ static enum print_line_t kmemtrace_print_line(struct trace_iterator *iter)
 	}
 }
 
-static struct trace_event kmem_trace_alloc = {
-	.type			= TRACE_KMEM_ALLOC,
+static struct trace_event_functions kmem_trace_alloc_funcs = {
 	.trace			= kmemtrace_print_alloc,
 	.binary			= kmemtrace_print_alloc_user,
 };
 
-static struct trace_event kmem_trace_free = {
-	.type			= TRACE_KMEM_FREE,
+static struct trace_event kmem_trace_alloc = {
+	.type			= TRACE_KMEM_ALLOC,
+	.funcs			= &kmem_trace_alloc_funcs,
+};
+
+static struct trace_event_functions kmem_trace_free_funcs = {
 	.trace			= kmemtrace_print_free,
 	.binary			= kmemtrace_print_free_user,
 };
 
+static struct trace_event kmem_trace_free = {
+	.type			= TRACE_KMEM_FREE,
+	.funcs			= &kmem_trace_free_funcs,
+};
+
 static struct tracer kmem_tracer __read_mostly = {
 	.name			= "kmemtrace",
 	.init			= kmem_trace_init,

kernel/trace/trace.c

@@ -1936,7 +1936,7 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
 	}
 
 	if (event)
-		return event->trace(iter, sym_flags);
+		return event->funcs->trace(iter, sym_flags, event);
 
 	if (!trace_seq_printf(s, "Unknown type %d\n", entry->type))
 		goto partial;
@@ -1962,7 +1962,7 @@ static enum print_line_t print_raw_fmt(struct trace_iterator *iter)
 
 	event = ftrace_find_event(entry->type);
 	if (event)
-		return event->raw(iter, 0);
+		return event->funcs->raw(iter, 0, event);
 
 	if (!trace_seq_printf(s, "%d ?\n", entry->type))
 		goto partial;
@@ -1989,7 +1989,7 @@ static enum print_line_t print_hex_fmt(struct trace_iterator *iter)
 
 	event = ftrace_find_event(entry->type);
 	if (event) {
-		enum print_line_t ret = event->hex(iter, 0);
+		enum print_line_t ret = event->funcs->hex(iter, 0, event);
 		if (ret != TRACE_TYPE_HANDLED)
 			return ret;
 	}
@@ -2014,7 +2014,8 @@ static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
 	}
 
 	event = ftrace_find_event(entry->type);
-	return event ? event->binary(iter, 0) : TRACE_TYPE_HANDLED;
+	return event ? event->funcs->binary(iter, 0, event) :
+		TRACE_TYPE_HANDLED;
 }
 
 int trace_empty(struct trace_iterator *iter)

kernel/trace/trace_branch.c

@@ -143,7 +143,7 @@ static void branch_trace_reset(struct trace_array *tr)
 }
 
 static enum print_line_t trace_branch_print(struct trace_iterator *iter,
-					    int flags)
+					    int flags, struct trace_event *event)
 {
 	struct trace_branch *field;
 
@@ -167,9 +167,13 @@ static void branch_print_header(struct seq_file *s)
 		"    |\n");
 }
 
+static struct trace_event_functions trace_branch_funcs = {
+	.trace		= trace_branch_print,
+};
+
 static struct trace_event trace_branch_event = {
 	.type		= TRACE_BRANCH,
-	.trace		= trace_branch_print,
+	.funcs		= &trace_branch_funcs,
 };
 
 static struct tracer branch_trace __read_mostly =

kernel/trace/trace_functions_graph.c

@@ -1025,7 +1025,7 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
 		if (!event)
 			return TRACE_TYPE_UNHANDLED;
 
-		ret = event->trace(iter, sym_flags);
+		ret = event->funcs->trace(iter, sym_flags, event);
 		if (ret != TRACE_TYPE_HANDLED)
 			return ret;
 	}
@@ -1112,7 +1112,8 @@ print_graph_function(struct trace_iterator *iter)
 }
 
 static enum print_line_t
-print_graph_function_event(struct trace_iterator *iter, int flags)
+print_graph_function_event(struct trace_iterator *iter, int flags,
+			   struct trace_event *event)
 {
 	return print_graph_function(iter);
 }
@@ -1225,14 +1226,18 @@ void graph_trace_close(struct trace_iterator *iter)
 	}
 }
 
+static struct trace_event_functions graph_functions = {
+	.trace		= print_graph_function_event,
+};
+
 static struct trace_event graph_trace_entry_event = {
 	.type		= TRACE_GRAPH_ENT,
-	.trace		= print_graph_function_event,
+	.funcs		= &graph_functions,
 };
 
 static struct trace_event graph_trace_ret_event = {
 	.type		= TRACE_GRAPH_RET,
-	.trace		= print_graph_function_event,
+	.funcs		= &graph_functions
 };
 
 static struct tracer graph_trace __read_mostly = {

kernel/trace/trace_kprobe.c

@@ -1011,16 +1011,15 @@ static __kprobes void kretprobe_trace_func(struct kretprobe_instance *ri,
 
 /* Event entry printers */
 enum print_line_t
-print_kprobe_event(struct trace_iterator *iter, int flags)
+print_kprobe_event(struct trace_iterator *iter, int flags,
+		   struct trace_event *event)
 {
 	struct kprobe_trace_entry *field;
 	struct trace_seq *s = &iter->seq;
-	struct trace_event *event;
 	struct trace_probe *tp;
 	int i;
 
 	field = (struct kprobe_trace_entry *)iter->ent;
-	event = ftrace_find_event(field->ent.type);
 	tp = container_of(event, struct trace_probe, event);
 
 	if (!trace_seq_printf(s, "%s: (", tp->call.name))
@@ -1046,16 +1045,15 @@ print_kprobe_event(struct trace_iterator *iter, int flags)
 }
 
 enum print_line_t
-print_kretprobe_event(struct trace_iterator *iter, int flags)
+print_kretprobe_event(struct trace_iterator *iter, int flags,
+		      struct trace_event *event)
 {
 	struct kretprobe_trace_entry *field;
 	struct trace_seq *s = &iter->seq;
-	struct trace_event *event;
 	struct trace_probe *tp;
 	int i;
 
 	field = (struct kretprobe_trace_entry *)iter->ent;
-	event = ftrace_find_event(field->ent.type);
 	tp = container_of(event, struct trace_probe, event);
 
 	if (!trace_seq_printf(s, "%s: (", tp->call.name))
@@ -1351,6 +1349,14 @@ int kretprobe_dispatcher(struct kretprobe_instance *ri, struct pt_regs *regs)
 	return 0;	/* We don't tweek kernel, so just return 0 */
 }
 
+static struct trace_event_functions kretprobe_funcs = {
+	.trace		= print_kretprobe_event
+};
+
+static struct trace_event_functions kprobe_funcs = {
+	.trace		= print_kprobe_event
+};
+
 static int register_probe_event(struct trace_probe *tp)
 {
 	struct ftrace_event_call *call = &tp->call;
@@ -1358,13 +1364,13 @@ static int register_probe_event(struct trace_probe *tp)
 
 	/* Initialize ftrace_event_call */
 	if (probe_is_return(tp)) {
-		tp->event.trace = print_kretprobe_event;
+		tp->event.funcs = &kretprobe_funcs;
 		INIT_LIST_HEAD(&call->class->fields);
 		call->class->raw_init = probe_event_raw_init;
 		call->class->define_fields = kretprobe_event_define_fields;
 	} else {
 		INIT_LIST_HEAD(&call->class->fields);
-		tp->event.trace = print_kprobe_event;
+		tp->event.funcs = &kprobe_funcs;
 		call->class->raw_init = probe_event_raw_init;
 		call->class->define_fields = kprobe_event_define_fields;
 	}

kernel/trace/trace_output.h

@@ -25,7 +25,7 @@ extern void trace_event_read_unlock(void);
 extern struct trace_event *ftrace_find_event(int type);
 
 extern enum print_line_t trace_nop_print(struct trace_iterator *iter,
-					 int flags);
+					 int flags, struct trace_event *event);
 extern int
 trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry);
 

kernel/trace/trace_syscalls.c

@@ -93,7 +93,8 @@ static struct syscall_metadata *syscall_nr_to_meta(int nr)
 }
 
 enum print_line_t
-print_syscall_enter(struct trace_iterator *iter, int flags)
+print_syscall_enter(struct trace_iterator *iter, int flags,
+		    struct trace_event *event)
 {
 	struct trace_seq *s = &iter->seq;
 	struct trace_entry *ent = iter->ent;
@@ -145,7 +146,8 @@ print_syscall_enter(struct trace_iterator *iter, int flags)
 }
 
 enum print_line_t
-print_syscall_exit(struct trace_iterator *iter, int flags)
+print_syscall_exit(struct trace_iterator *iter, int flags,
+		   struct trace_event *event)
 {
 	struct trace_seq *s = &iter->seq;
 	struct trace_entry *ent = iter->ent;