powerpc32, ftrace: dynamic function graph tracer

This patch gets function graph tracing working with dynamic function
tracer on PowerPC32.

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/Kconfig

@@ -111,7 +111,7 @@ config PPC
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_FUNCTION_TRACER
-	select HAVE_FUNCTION_GRAPH_TRACER if PPC64 || !DYNAMIC_FTRACE
+	select HAVE_FUNCTION_GRAPH_TRACER
 	select ARCH_WANT_OPTIONAL_GPIOLIB
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT

arch/powerpc/kernel/entry_32.S

@@ -1183,7 +1183,12 @@ _GLOBAL(ftrace_caller)
 ftrace_call:
 	bl	ftrace_stub
 	nop
-
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+.globl ftrace_graph_call
+ftrace_graph_call:
+	b	ftrace_graph_stub
+_GLOBAL(ftrace_graph_stub)
+#endif
 	MCOUNT_RESTORE_FRAME
 	/* old link register ends up in ctr reg */
 	bctr
@@ -1205,7 +1210,6 @@ _GLOBAL(_mcount)
 	b	ftrace_graph_caller
 #endif
 	MCOUNT_RESTORE_FRAME
-	
 	bctr
 #endif