powerpc: Implement ftrace_enabled() helpers

Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Reviewed-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Link: https://lore.kernel.org/r/20200508043408.886394-13-npiggin@gmail.com

arch/powerpc/include/asm/ftrace.h

@@ -108,9 +108,23 @@ static inline void this_cpu_enable_ftrace(void)
 {
 	get_paca()->ftrace_enabled = 1;
 }
+
+/* Disable ftrace on this CPU if possible (may not be implemented) */
+static inline void this_cpu_set_ftrace_enabled(u8 ftrace_enabled)
+{
+	get_paca()->ftrace_enabled = ftrace_enabled;
+}
+
+static inline u8 this_cpu_get_ftrace_enabled(void)
+{
+	return get_paca()->ftrace_enabled;
+}
+
 #else /* CONFIG_PPC64 */
 static inline void this_cpu_disable_ftrace(void) { }
 static inline void this_cpu_enable_ftrace(void) { }
+static inline void this_cpu_set_ftrace_enabled(u8 ftrace_enabled) { }
+static inline u8 this_cpu_get_ftrace_enabled(void) { return 1; }
 #endif /* CONFIG_PPC64 */
 #endif /* !__ASSEMBLY__ */