FAILED: patch "[PATCH] powerpc/function_graph: Simplify with function_graph_enter()" failed to apply to 4.4-stable tree

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: "Steven Rostedt (VMware)" <[email protected]>
Date: Sun, 18 Nov 2018 17:28:53 -0500
Subject: [PATCH] powerpc/function_graph: Simplify with function_graph_enter()

The function_graph_enter() function does the work of calling the function graph hook function and the management of the shadow stack, simplifying the work done in the architecture dependent prepare_ftrace_return().

Have powerpc use the new code, and remove the shadow stack management as well as having to set up the trace structure.

This is needed to prepare for a fix of a design bug on how the curr_ret_stack is used.

index 4bf051d3e21e..b65c8a34ad6e 100644
@@ -950,7 +950,6 @@ int ftrace_disable_ftrace_graph_caller(void)
  */
 unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
 {
-	struct ftrace_graph_ent trace;
 	unsigned long return_hooker;
 
 	if (unlikely(ftrace_graph_is_dead()))

@@ -961,18 +960,8 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
 
 	return_hooker = ppc_function_entry(return_to_handler);
 
-	trace.func = ip;
-	trace.depth = current->curr_ret_stack + 1;
-
-	/* Only trace if the calling function expects to */
-	if (!ftrace_graph_entry(&trace))
-		goto out;
-
-	if (ftrace_push_return_trace(parent, ip, &trace.depth, 0,
-				     NULL) == -EBUSY)
-		goto out;
-
-	parent = return_hooker;
+	if (!function_graph_enter(parent, ip, 0, NULL))
+		parent = return_hooker;
 out:
 	return parent;
 }