sh/ftrace: Move arch_ftrace_nmi_{enter,exit} into nmi exception

SuperH is the last remaining user of arch_ftrace_nmi_{enter,exit}(),
remove it from the generic code and into the SuperH code.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: https://lkml.kernel.org/r/20200505134101.248881738@linutronix.de

Documentation/trace/ftrace-design.rst

@@ -229,14 +229,6 @@ Adding support for it is easy: just define the macro in asm/ftrace.h and
 pass the return address pointer as the 'retp' argument to
 ftrace_push_return_trace().
 
-HAVE_FTRACE_NMI_ENTER
----------------------
-
-If you can't trace NMI functions, then skip this option.
-
-<details to be filled>
-
-
 HAVE_SYSCALL_TRACEPOINTS
 ------------------------
 

arch/sh/Kconfig

@@ -71,7 +71,6 @@ config SUPERH32
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FTRACE_MCOUNT_RECORD
 	select HAVE_DYNAMIC_FTRACE
-	select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_ARCH_KGDB

arch/sh/kernel/traps.c

@@ -170,11 +170,21 @@ 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)
 {
 	unsigned int cpu = smp_processor_id();
 	TRAP_HANDLER_DECL;
 
+	arch_ftrace_nmi_enter();
+
 	nmi_enter();
 	nmi_count(cpu)++;
 
@@ -190,4 +200,6 @@ BUILD_TRAP_HANDLER(nmi)
 	}
 
 	nmi_exit();
+
+	arch_ftrace_nmi_exit();
 }

include/linux/ftrace_irq.h

@@ -2,15 +2,6 @@
 #ifndef _LINUX_FTRACE_IRQ_H
 #define _LINUX_FTRACE_IRQ_H
 
-
-#ifdef CONFIG_FTRACE_NMI_ENTER
-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
-
 #ifdef CONFIG_HWLAT_TRACER
 extern bool trace_hwlat_callback_enabled;
 extern void trace_hwlat_callback(bool enter);
@@ -22,12 +13,10 @@ static inline void ftrace_nmi_enter(void)
 	if (trace_hwlat_callback_enabled)
 		trace_hwlat_callback(true);
 #endif
-	arch_ftrace_nmi_enter();
 }
 
 static inline void ftrace_nmi_exit(void)
 {
-	arch_ftrace_nmi_exit();
 #ifdef CONFIG_HWLAT_TRACER
 	if (trace_hwlat_callback_enabled)
 		trace_hwlat_callback(false);

kernel/trace/Kconfig

@@ -10,11 +10,6 @@ config USER_STACKTRACE_SUPPORT
 config NOP_TRACER
 	bool
 
-config HAVE_FTRACE_NMI_ENTER
-	bool
-	help
-	  See Documentation/trace/ftrace-design.rst
-
 config HAVE_FUNCTION_TRACER
 	bool
 	help
@@ -72,11 +67,6 @@ config RING_BUFFER
 	select TRACE_CLOCK
 	select IRQ_WORK
 
-config FTRACE_NMI_ENTER
-       bool
-       depends on HAVE_FTRACE_NMI_ENTER
-       default y
-
 config EVENT_TRACING
 	select CONTEXT_SWITCH_TRACER
 	select GLOB