x86/entry: Fix NMI vs IRQ state tracking

While the nmi_enter() users did
trace_hardirqs_{off_prepare,on_finish}() there was no matching
lockdep_hardirqs_*() calls to complete the picture.

Introduce idtentry_{enter,exit}_nmi() to enable proper IRQ state
tracking across the NMIs.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200623083721.216740948@infradead.org

include/linux/hardirq.h

@@ -111,32 +111,42 @@ extern void rcu_nmi_exit(void);
 /*
  * nmi_enter() can nest up to 15 times; see NMI_BITS.
  */
-#define nmi_enter()						\
+#define __nmi_enter()						\
 	do {							\
+		lockdep_off();					\
 		arch_nmi_enter();				\
 		printk_nmi_enter();				\
-		lockdep_off();					\
 		BUG_ON(in_nmi() == NMI_MASK);			\
 		__preempt_count_add(NMI_OFFSET + HARDIRQ_OFFSET);	\
-		rcu_nmi_enter();				\
+	} while (0)
+
+#define nmi_enter()						\
+	do {							\
+		__nmi_enter();					\
 		lockdep_hardirq_enter();			\
+		rcu_nmi_enter();				\
 		instrumentation_begin();			\
 		ftrace_nmi_enter();				\
 		instrumentation_end();				\
 	} while (0)
 
+#define __nmi_exit()						\
+	do {							\
+		BUG_ON(!in_nmi());				\
+		__preempt_count_sub(NMI_OFFSET + HARDIRQ_OFFSET);	\
+		printk_nmi_exit();				\
+		arch_nmi_exit();				\
+		lockdep_on();					\
+	} while (0)
+
 #define nmi_exit()						\
 	do {							\
 		instrumentation_begin();			\
 		ftrace_nmi_exit();				\
 		instrumentation_end();				\
-		lockdep_hardirq_exit();				\
 		rcu_nmi_exit();					\
-		BUG_ON(!in_nmi());				\
-		__preempt_count_sub(NMI_OFFSET + HARDIRQ_OFFSET);	\
-		lockdep_on();					\
-		printk_nmi_exit();				\
-		arch_nmi_exit();				\
+		lockdep_hardirq_exit();				\
+		__nmi_exit();					\
 	} while (0)
 
 #endif /* LINUX_HARDIRQ_H */