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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: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A5E964A.9000403@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Li Zefan 2009-07-16 10:54:02 +08:00 committed by Steven Rostedt
parent 68fd60a8c8
commit 7d536cb3fb
2 changed files with 12 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
include/trace/ftrace.h
View File

@ -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

6
kernel/trace/trace_events_filter.c
View File

@ -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;