tools lib traceevent: Handle __attribute__((user)) in field names

Commit c61f13ea ("gcc-plugins: Add structleak for more stack
initialization") added "__attribute__((user))" to the user when
stackleak detector is enabled. This now appears in the field format of
system call trace events for system calls that have user buffers. The
"__attribute__((user))" breaks the parsing in libtraceevent. That needs
to be handled.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jaewon Kim <jaewon31.kim@samsung.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kees Kook <keescook@chromium.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: linux-mm@kvack.org
Cc: linux-trace-devel@vger.kernel.org
Link: http://lore.kernel.org/lkml/20200324200956.663647256@goodmis.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/traceevent/event-parse.c

@@ -1444,6 +1444,7 @@ static int event_read_fields(struct tep_event *event, struct tep_format_field **
 	enum tep_event_type type;
 	char *token;
 	char *last_token;
+	char *delim = " ";
 	int count = 0;
 	int ret;
 
@@ -1504,13 +1505,49 @@ static int event_read_fields(struct tep_event *event, struct tep_format_field **
 					field->flags |= TEP_FIELD_IS_POINTER;
 
 				if (field->type) {
-					ret = append(&field->type, " ", last_token);
+					ret = append(&field->type, delim, last_token);
 					free(last_token);
 					if (ret < 0)
 						goto fail;
 				} else
 					field->type = last_token;
 				last_token = token;
+				delim = " ";
+				continue;
+			}
+
+			/* Handle __attribute__((user)) */
+			if ((type == TEP_EVENT_DELIM) &&
+			    strcmp("__attribute__", last_token) == 0 &&
+			    token[0] == '(') {
+				int depth = 1;
+				int ret;
+
+				ret = append(&field->type, " ", last_token);
+				ret |= append(&field->type, "", "(");
+				if (ret < 0)
+					goto fail;
+
+				delim = " ";
+				while ((type = read_token(&token)) != TEP_EVENT_NONE) {
+					if (type == TEP_EVENT_DELIM) {
+						if (token[0] == '(')
+							depth++;
+						else if (token[0] == ')')
+							depth--;
+						if (!depth)
+							break;
+						ret = append(&field->type, "", token);
+						delim = "";
+					} else {
+						ret = append(&field->type, delim, token);
+						delim = " ";
+					}
+					if (ret < 0)
+						goto fail;
+					free(last_token);
+					last_token = token;
+				}
 				continue;
 			}
 			break;