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>

1 files changed, 4 insertions, 2 deletions

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index b9aae72d13db..1c80ef702b83 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -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;