perf tools: Complete support for dynamic strings

Complete support for __str_loc type strings of ftrace events
which have dynamic offsets values set for each of them inside
their sammples.

Before:
        geany-5759  [000]     0.000000: lock_release: name
        geany-5759  [000]     0.000000: lock_release: name
        geany-5759  [000]     0.000000: lock_release: name
  kondemand/0-362   [000]     0.000000: lock_release: name
      pdflush-421   [000]     0.000000: lock_release: name

After:
        geany-5759  [000]     0.000000: lock_release: &u->lock
        geany-5759  [000]     0.000000: lock_release: key
        geany-5759  [000]     0.000000: lock_release: &group->notification_mutex
  kondemand/0-362   [000]     0.000000: lock_release: &rq->lock
      pdflush-421   [000]     0.000000: lock_release: &rq->lock

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1251693921-6579-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>

2 files changed, 15 insertions, 2 deletions

diff --git a/tools/perf/util/trace-event-parse.c b/tools/perf/util/trace-event-parse.c
index 96c5e97ffe7b..665dac20cd1e 100644
--- a/tools/perf/util/trace-event-parse.c
+++ b/tools/perf/util/trace-event-parse.c
@@ -1548,6 +1548,7 @@ process_str(struct event *event __unused, struct print_arg *arg, char **tok)
 
         arg->type = PRINT_STRING;
         arg->string.string = token;
+        arg->string.offset = -1;
 
         if (read_expected(EVENT_DELIM, (char *)")") < 0)
                 return EVENT_ERROR;
@@ -2031,9 +2032,20 @@ static void print_str_arg(void *data, int size,
 
         case PRINT_TYPE:
                 break;
-        case PRINT_STRING:
-                printf("%s", arg->string.string);
+        case PRINT_STRING: {
+                int str_offset;
+
+                if (arg->string.offset == -1) {
+                        struct format_field *f;
+
+                        f = find_any_field(event, arg->string.string);
+                        arg->string.offset = f->offset;
+                }
+                str_offset = *(int *)(data + arg->string.offset);
+                str_offset &= 0xffff;
+                printf("%s", ((char *)data) + str_offset);
                 break;
+        }
         case PRINT_OP:
                 /*
                  * The only op for string should be ? :
diff --git a/tools/perf/util/trace-event.h b/tools/perf/util/trace-event.h
index 051fcf363825..420294a5773e 100644
--- a/tools/perf/util/trace-event.h
+++ b/tools/perf/util/trace-event.h
@@ -50,6 +50,7 @@ struct print_arg_atom {
 
 struct print_arg_string {
         char                    *string;
+        int                     offset;
 };
 
 struct print_arg_field {