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, 39 insertions, 67 deletions

diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
index 45630a76ed3a..6d64c1c19fd5 100644
--- a/kernel/trace/trace_export.c
+++ b/kernel/trace/trace_export.c
@@ -29,10 +29,8 @@ static int ftrace_event_register(struct trace_event_call *call,
  * function and thus become accesible via perf.
  */
 #undef FTRACE_ENTRY_REG
-#define FTRACE_ENTRY_REG(name, struct_name, id, tstruct, print, \
-			 filter, regfn) \
-	FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print), \
-		     filter)
+#define FTRACE_ENTRY_REG(name, struct_name, id, tstruct, print, regfn) \
+	FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print))
 
 /* not needed for this file */
 #undef __field_struct
@@ -41,6 +39,9 @@ static int ftrace_event_register(struct trace_event_call *call,
 #undef __field
 #define __field(type, item)				type item;
 
+#undef __field_fn
+#define __field_fn(type, item)				type item;
+
 #undef __field_desc
 #define __field_desc(type, container, item)		type item;
 
@@ -60,7 +61,7 @@ static int ftrace_event_register(struct trace_event_call *call,
 #define F_printk(fmt, args...) fmt, args
 
 #undef FTRACE_ENTRY
-#define FTRACE_ENTRY(name, struct_name, id, tstruct, print, filter)	\
+#define FTRACE_ENTRY(name, struct_name, id, tstruct, print)		\
 struct ____ftrace_##name {						\
 	tstruct								\
 };									\
@@ -73,76 +74,46 @@ static void __always_unused ____ftrace_check_##name(void)		\
 }
 
 #undef FTRACE_ENTRY_DUP
-#define FTRACE_ENTRY_DUP(name, struct_name, id, tstruct, print, filter)	\
-	FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print), \
-		     filter)
+#define FTRACE_ENTRY_DUP(name, struct_name, id, tstruct, print)		\
+	FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print))
 
 #include "trace_entries.h"
 
+#undef __field_ext
+#define __field_ext(_type, _item, _filter_type) {			\
+	.type = #_type, .name = #_item,					\
+	.size = sizeof(_type), .align = __alignof__(_type),		\
+	is_signed_type(_type), .filter_type = _filter_type },
+
 #undef __field
-#define __field(type, item)						\
-	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(_type, _item) __field_ext(_type, _item, FILTER_OTHER)
+
+#undef __field_fn
+#define __field_fn(_type, _item) __field_ext(_type, _item, FILTER_TRACE_FN)
 
 #undef __field_desc
-#define __field_desc(type, container, item)	\
-	ret = trace_define_field(event_call, #type, #item,		\
-				 offsetof(typeof(field),		\
-					  container.item),		\
-				 sizeof(field.container.item),		\
-				 is_signed_type(type), filter_type);	\
-	if (ret)							\
-		return ret;
+#define __field_desc(_type, _container, _item) __field_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);			\
-		ret = trace_define_field(event_call, type_str, #item,	\
-				 offsetof(typeof(field), item),		\
-				 sizeof(field.item),			\
-				 is_signed_type(type), filter_type);	\
-		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_type(_type), .filter_type = FILTER_OTHER },
 
 #undef __array_desc
-#define __array_desc(type, container, item, len)			\
-	BUILD_BUG_ON(len > MAX_FILTER_STR_VAL);				\
-	ret = trace_define_field(event_call, #type "[" #len "]", #item,	\
-				 offsetof(typeof(field),		\
-					  container.item),		\
-				 sizeof(field.container.item),		\
-				 is_signed_type(type), filter_type);	\
-	if (ret)							\
-		return ret;
+#define __array_desc(_type, _container, _item, _len) __array(_type, _item, _len)
 
 #undef __dynamic_array
-#define __dynamic_array(type, item)					\
-	ret = trace_define_field(event_call, #type "[]", #item,  \
-				 offsetof(typeof(field), item),		\
-				 0, is_signed_type(type), filter_type);\
-	if (ret)							\
-		return ret;
+#define __dynamic_array(_type, _item) {					\
+	.type = #_type "[]", .name = #_item,				\
+	.size = 0, .align = __alignof__(_type),				\
+	is_signed_type(_type), .filter_type = FILTER_OTHER },
 
 #undef FTRACE_ENTRY
-#define FTRACE_ENTRY(name, struct_name, id, tstruct, print, filter)	\
-static int __init							\
-ftrace_define_fields_##name(struct trace_event_call *event_call)	\
-{									\
-	struct struct_name field;					\
-	int ret;							\
-	int filter_type = filter;					\
-									\
-	tstruct;							\
-									\
-	return ret;							\
-}
+#define FTRACE_ENTRY(name, struct_name, id, tstruct, print)		\
+static struct trace_event_fields ftrace_event_fields_##name[] = {	\
+	tstruct								\
+	{} };
 
 #include "trace_entries.h"
 
@@ -152,6 +123,9 @@ ftrace_define_fields_##name(struct trace_event_call *event_call)	\
 #undef __field
 #define __field(type, item)
 
+#undef __field_fn
+#define __field_fn(type, item)
+
 #undef __field_desc
 #define __field_desc(type, container, item)
 
@@ -168,12 +142,10 @@ ftrace_define_fields_##name(struct trace_event_call *event_call)	\
 #define F_printk(fmt, args...) __stringify(fmt) ", "  __stringify(args)
 
 #undef FTRACE_ENTRY_REG
-#define FTRACE_ENTRY_REG(call, struct_name, etype, tstruct, print, filter,\
-			 regfn)						\
-									\
+#define FTRACE_ENTRY_REG(call, struct_name, etype, tstruct, print, regfn) \
 struct trace_event_class __refdata event_class_ftrace_##call = {	\
 	.system			= __stringify(TRACE_SYSTEM),		\
-	.define_fields		= ftrace_define_fields_##call,		\
+	.fields_array		= ftrace_event_fields_##call,		\
 	.fields			= LIST_HEAD_INIT(event_class_ftrace_##call.fields),\
 	.reg			= regfn,				\
 };									\
@@ -191,9 +163,9 @@ struct trace_event_call __used						\
 __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call;
 
 #undef FTRACE_ENTRY
-#define FTRACE_ENTRY(call, struct_name, etype, tstruct, print, filter)	\
+#define FTRACE_ENTRY(call, struct_name, etype, tstruct, print)		\
 	FTRACE_ENTRY_REG(call, struct_name, etype,			\
-			 PARAMS(tstruct), PARAMS(print), filter, NULL)
+			 PARAMS(tstruct), PARAMS(print), NULL)
 
 bool ftrace_event_is_function(struct trace_event_call *call)
 {