tools lib traceevent: Handle __print_hex(__get_dynamic_array(fieldname), len)

The kernel has a few events with a format similar to this excerpt:
        field:unsigned int len;     offset:12;      size:4; signed:0;
        field:__data_loc unsigned char[] data_array;  offset:16;      size:4; signed:0;
print fmt: "%s", __print_hex(__get_dynamic_array(data_array), REC->len)

trace-cmd could already parse that arg correctly, but print_str_arg()
was unable to handle the first parameter being a dynamic array. (It
just printed a "field not found" warning).

Teach print_str_arg's PRINT_HEX case to handle the nested
PRINT_DYNAMIC_ARRAY correctly. The output now matches the kernel's own
formatting for this case.

Signed-off-by: Howard Cochran <hcochran@lexmark.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1381503349-12271-1-git-send-email-hcochran@lexmark.com
[ Removed "polish compare", we don't do that here ]
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 16 insertions, 8 deletions

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 013c8d3db806..0a1ffe07de3f 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -3588,15 +3588,23 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
                 }
                 break;
         case PRINT_HEX:
-                field = arg->hex.field->field.field;
-                if (!field) {
-                        str = arg->hex.field->field.name;
-                        field = pevent_find_any_field(event, str);
-                        if (!field)
-                                goto out_warning_field;
-                        arg->hex.field->field.field = field;
+                if (arg->hex.field->type == PRINT_DYNAMIC_ARRAY) {
+                        unsigned long offset;
+                        offset = pevent_read_number(pevent,
+                                data + arg->hex.field->dynarray.field->offset,
+                                arg->hex.field->dynarray.field->size);
+                        hex = data + (offset & 0xffff);
+                } else {
+                        field = arg->hex.field->field.field;
+                        if (!field) {
+                                str = arg->hex.field->field.name;
+                                field = pevent_find_any_field(event, str);
+                                if (!field)
+                                        goto out_warning_field;
+                                arg->hex.field->field.field = field;
+                        }
+                        hex = data + field->offset;
                 }
-                hex = data + field->offset;
                 len = eval_num_arg(data, size, event, arg->hex.size);
                 for (i = 0; i < len; i++) {
                         if (i)