ftrace,kcfi: Define ftrace_stub_graph conditionally

From: Arnd Bergmann <[email protected]>

When CONFIG_FUNCTION_GRAPH_TRACER is disabled, __kcfi_typeid_ftrace_stub_graph is missing, causing a link failure:

ld.lld: error: undefined symbol: __kcfi_typeid_ftrace_stub_graph referenced by arch/x86/kernel/ftrace_64.o:(__cfi_ftrace_stub_graph) in archive vmlinux.a

Mark the reference to it as conditional on the same symbol, as is done on arm64.

See-also: 2598ac6ec493 ("arm64: ftrace: Define ftrace_stub_graph only with FUNCTION_GRAPH_TRACER")

---
 arch/x86/kernel/ftrace_64.S | 2 ++
 1 file changed, 2 insertions(+)

index 1265ad519249..fb4f1e01b64a 100644
@@ -136,10 +136,12 @@ SYM_TYPED_FUNC_START(ftrace_stub)
 	RET
 SYM_FUNC_END(ftrace_stub)
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
 SYM_TYPED_FUNC_START(ftrace_stub_graph)
 	CALL_DEPTH_ACCOUNT
 	RET
 SYM_FUNC_END(ftrace_stub_graph)
+#endif
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 

2.39.0