sh: ftrace: Fix missing prototypes

arch/sh/kernel/ftrace.c:130:6: warning: no previous prototype for ‘arch_ftrace_nmi_enter’ [-Wmissing-prototypes]
arch/sh/kernel/ftrace.c:140:6: warning: no previous prototype for ‘arch_ftrace_nmi_exit’ [-Wmissing-prototypes]
arch/sh/kernel/ftrace.c:316:6: warning: no previous prototype for ‘prepare_ftrace_return’ [-Wmissing-prototypes]

Fix this by moving existing forward declarations to <asm/ftrace.h>, and
adding the missing forward declaration for prepare_ftrace_return().
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/910c8846a025e1c3b744a83ddf8e2816a3c5569d.1709326528.git.geert+renesas@glider.beSigned-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

arch/sh/include/asm/ftrace.h

@@ -33,6 +33,8 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
 	return addr;
 }
 
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr);
+
 #endif /* __ASSEMBLY__ */
 #endif /* CONFIG_FUNCTION_TRACER */
 
@@ -43,6 +45,14 @@ extern void *return_address(unsigned int);
 
 #define ftrace_return_address(n) return_address(n)
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+extern void arch_ftrace_nmi_enter(void);
+extern void arch_ftrace_nmi_exit(void);
+#else
+static inline void arch_ftrace_nmi_enter(void) { }
+static inline void arch_ftrace_nmi_exit(void) { }
+#endif
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* __ASM_SH_FTRACE_H */

arch/sh/kernel/traps.c

@@ -15,6 +15,8 @@
 
 #include <linux/extable.h>
 #include <linux/module.h>	/* print_modules */
+
+#include <asm/ftrace.h>
 #include <asm/unwinder.h>
 #include <asm/traps.h>
 
@@ -170,14 +172,6 @@ BUILD_TRAP_HANDLER(bug)
 	force_sig(SIGTRAP);
 }
 
-#ifdef CONFIG_DYNAMIC_FTRACE
-extern void arch_ftrace_nmi_enter(void);
-extern void arch_ftrace_nmi_exit(void);
-#else
-static inline void arch_ftrace_nmi_enter(void) { }
-static inline void arch_ftrace_nmi_exit(void) { }
-#endif
-
 BUILD_TRAP_HANDLER(nmi)
 {
 	TRAP_HANDLER_DECL;