ftrace: Rework event_create_dir()

Rework event_create_dir() to use an array of static data instead of
function pointers where possible.

The problem is that it would call the function pointer on module load
before parse_args(), possibly even before jump_labels were initialized.
Luckily the generated functions don't use jump_labels but it still seems
fragile. It also gets in the way of changing when we make the module map
executable.

The generated function are basically calling trace_define_field() with a
bunch of static arguments. So instead of a function, capture these
arguments in a static array, avoiding the function call.

Now there are a number of cases where the fields are dynamic (syscall
arguments, kprobes and uprobes), in which case a static array does not
work, for these we preserve the function call. Luckily all these cases
are not related to modules and so we can retain the function call for
them.

Also fix up all broken tracepoint definitions that now generate a
compile error.

Tested-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191111132458.342979914@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 21 insertions, 43 deletions

diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h
index 4ecdfe2e3580..ca1d2e745a3f 100644
--- a/include/trace/trace_events.h
+++ b/include/trace/trace_events.h
@@ -394,22 +394,16 @@ static struct trace_event_functions trace_event_type_funcs_##call = {	\
 #include TRACE_INCLUDE(TRACE_INCLUDE_FILE)
 
 #undef __field_ext
-#define __field_ext(type, item, filter_type)				\
-	ret = trace_define_field(event_call, #type, #item,		\
-				 offsetof(typeof(field), item),		\
-				 sizeof(field.item),			\
-				 is_signed_type(type), filter_type);	\
-	if (ret)							\
-		return ret;
+#define __field_ext(_type, _item, _filter_type) {			\
+	.type = #_type, .name = #_item,					\
+	.size = sizeof(_type), .align = __alignof__(_type),		\
+	.is_signed = is_signed_type(_type), .filter_type = _filter_type },
 
 #undef __field_struct_ext
-#define __field_struct_ext(type, item, filter_type)			\
-	ret = trace_define_field(event_call, #type, #item,		\
-				 offsetof(typeof(field), item),		\
-				 sizeof(field.item),			\
-				 0, filter_type);			\
-	if (ret)							\
-		return ret;
+#define __field_struct_ext(_type, _item, _filter_type) {		\
+	.type = #_type, .name = #_item,					\
+	.size = sizeof(_type), .align = __alignof__(_type),		\
+	0, .filter_type = _filter_type },
 
 #undef __field
 #define __field(type, item)	__field_ext(type, item, FILTER_OTHER)
@@ -418,25 +412,16 @@ static struct trace_event_functions trace_event_type_funcs_##call = {	\
 #define __field_struct(type, item) __field_struct_ext(type, item, FILTER_OTHER)
 
 #undef __array
-#define __array(type, item, len)					\
-	do {								\
-		char *type_str = #type"["__stringify(len)"]";		\
-		BUILD_BUG_ON(len > MAX_FILTER_STR_VAL);			\
-		BUILD_BUG_ON(len <= 0);					\
-		ret = trace_define_field(event_call, type_str, #item,	\
-				 offsetof(typeof(field), item),		\
-				 sizeof(field.item),			\
-				 is_signed_type(type), FILTER_OTHER);	\
-		if (ret)						\
-			return ret;					\
-	} while (0);
+#define __array(_type, _item, _len) {					\
+	.type = #_type"["__stringify(_len)"]", .name = #_item,		\
+	.size = sizeof(_type[_len]), .align = __alignof__(_type),	\
+	.is_signed = is_signed_type(_type), .filter_type = FILTER_OTHER },
 
 #undef __dynamic_array
-#define __dynamic_array(type, item, len)				       \
-	ret = trace_define_field(event_call, "__data_loc " #type "[]", #item,  \
-				 offsetof(typeof(field), __data_loc_##item),   \
-				 sizeof(field.__data_loc_##item),	       \
-				 is_signed_type(type), FILTER_OTHER);
+#define __dynamic_array(_type, _item, _len) {				\
+	.type = "__data_loc " #_type "[]", .name = #_item,		\
+	.size = 4, .align = 4,						\
+	.is_signed = is_signed_type(_type), .filter_type = FILTER_OTHER },
 
 #undef __string
 #define __string(item, src) __dynamic_array(char, item, -1)
@@ -446,16 +431,9 @@ static struct trace_event_functions trace_event_type_funcs_##call = {	\
 
 #undef DECLARE_EVENT_CLASS
 #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, func, print)	\
-static int notrace __init						\
-trace_event_define_fields_##call(struct trace_event_call *event_call)	\
-{									\
-	struct trace_event_raw_##call field;				\
-	int ret;							\
-									\
-	tstruct;							\
-									\
-	return ret;							\
-}
+static struct trace_event_fields trace_event_fields_##call[] = {	\
+	tstruct								\
+	{} };
 
 #undef DEFINE_EVENT
 #define DEFINE_EVENT(template, name, proto, args)
@@ -613,7 +591,7 @@ static inline notrace int trace_event_get_offsets_##call(		\
  *
  * static struct trace_event_class __used event_class_<template> = {
  *	.system			= "<system>",
- *	.define_fields		= trace_event_define_fields_<call>,
+ *	.fields_array		= trace_event_fields_<call>,
  *	.fields			= LIST_HEAD_INIT(event_class_##call.fields),
  *	.raw_init		= trace_event_raw_init,
  *	.probe			= trace_event_raw_event_##call,
@@ -761,7 +739,7 @@ _TRACE_PERF_PROTO(call, PARAMS(proto));					\
 static char print_fmt_##call[] = print;					\
 static struct trace_event_class __used __refdata event_class_##call = { \
 	.system			= TRACE_SYSTEM_STRING,			\
-	.define_fields		= trace_event_define_fields_##call,	\
+	.fields_array		= trace_event_fields_##call,		\
 	.fields			= LIST_HEAD_INIT(event_class_##call.fields),\
 	.raw_init		= trace_event_raw_init,			\
 	.probe			= trace_event_raw_event_##call,		\