Fix the extension trace.so for RHEL7.6, which moved

ftrace_event_call.data into an anonymous union, and the

previous offset has changed, so the trace.so extension

module fails to load, indicating "no commands registered:

shared object unloaded".

--- crash-trace-command-2.0/trace.c.orig

+++ crash-trace-command-2.0/trace.c

@@ -853,8 +853,18 @@ static int syscall_get_enter_fields(ulon

 	inited = 1;

 	data_offset = MAX(MEMBER_OFFSET("ftrace_event_call", "data"), 

 		MEMBER_OFFSET("trace_event_call", "data"));

-	if (data_offset < 0)

-		return -1;

+	if (data_offset < 0) {

+		/*

+		 *  rhel-7.6 moved the .data member into an anonymous union.

+		 */

+		if (MEMBER_EXISTS("ftrace_event_call", "rh_data") &&

+		    MEMBER_EXISTS("ftrace_event_data", "data")) {

+			data_offset = MEMBER_OFFSET("ftrace_event_call", "rh_data") +

+				MEMBER_OFFSET("ftrace_event_data", "data");

+			inited = 2;

+		} else

+			return -1;

+	}

 	enter_fields_offset = MEMBER_OFFSET("syscall_metadata", "enter_fields");

 	if (enter_fields_offset < 0)

@@ -868,6 +878,12 @@ work:

 			"read ftrace_event_call data", RETURN_ON_ERROR))

 		return -1;

+	if (inited == 2) {

+		if (!readmem(metadata, KVADDR, &metadata, sizeof(metadata),

+		    "read ftrace_event_call data (indirect rh_data)", RETURN_ON_ERROR))

+			return -1;

+	}

+

 	*fields = metadata + enter_fields_offset;

 	return 0;

 }