Commit 7d536cb3 authored by Li Zefan's avatar Li Zefan Committed by Steven Rostedt
Browse files

tracing/events: record the size of dynamic arrays 



When a dynamic array is defined, we add __data_loc_foo in
trace_entry to record the offset of the array, but the
size of the array is not recorded, which causes 2 problems:

- the event filter just compares the first 2 chars of the strings.

- parsers can't parse dynamic arrays.

So we encode the size of each dynamic array in the higher 16 bits
of __data_loc_foo, while the offset is in lower 16 bits.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A5E964A.9000403@cn.fujitsu.com>
Acked-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 68fd60a8

include/trace/ftrace.h

+8 −6
Original line number Diff line number Diff line
@@ -25,7 +25,7 @@ 
#define __array(type, item, len)	type	item[len];



#undef __dynamic_array

#define __dynamic_array(type, item, len) unsigned short __data_loc_##item;

#define __dynamic_array(type, item, len) u32 __data_loc_##item;



#undef __string

#define __string(item, src) __dynamic_array(char, item, -1)
@@ -51,13 +51,14 @@ 
 * Include the following:

 *

 * struct ftrace_data_offsets_<call> {

 *	int				<item1>;

 *	int				<item2>;

 *	u32				<item1>;

 *	u32				<item2>;

 *	[...]

 * };

 *

 * The __dynamic_array() macro will create each int <item>, this is

 * The __dynamic_array() macro will create each u32 <item>, this is

 * to keep the offset of each array from the beginning of the event.

 * The size of an array is also encoded, in the higher 16 bits of <item>.

 */



#undef __field
@@ -67,7 +68,7 @@ 
#define __array(type, item, len)



#undef __dynamic_array

#define __dynamic_array(type, item, len)	int item;

#define __dynamic_array(type, item, len)	u32 item;



#undef __string

#define __string(item, src) __dynamic_array(char, item, -1)
@@ -207,7 +208,7 @@ ftrace_format_##call(struct trace_seq *s) \ 


#undef __get_dynamic_array

#define __get_dynamic_array(field)	\

		((void *)__entry + __entry->__data_loc_##field)

		((void *)__entry + (__entry->__data_loc_##field & 0xffff))



#undef __get_str

#define __get_str(field) (char *)__get_dynamic_array(field)
@@ -325,6 +326,7 @@ ftrace_define_fields_##call(void) \ 
#define __dynamic_array(type, item, len)				\

	__data_offsets->item = __data_size +				\

			       offsetof(typeof(*entry), __data);	\

	__data_offsets->item |= (len * sizeof(type)) << 16;		\

	__data_size += (len) * sizeof(type);



#undef __string

kernel/trace/trace_events_filter.c

+4 −2
Original line number Diff line number Diff line
@@ -176,11 +176,13 @@ static int filter_pred_string(struct filter_pred *pred, void *event, 
static int filter_pred_strloc(struct filter_pred *pred, void *event,

			      int val1, int val2)

{

	unsigned short str_loc = *(unsigned short *)(event + pred->offset);

	u32 str_item = *(u32 *)(event + pred->offset);

	int str_loc = str_item & 0xffff;

	int str_len = str_item >> 16;

	char *addr = (char *)(event + str_loc);

	int cmp, match;



	cmp = strncmp(addr, pred->str_val, pred->str_len);

	cmp = strncmp(addr, pred->str_val, str_len);



	match = (!cmp) ^ pred->not;

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