Merge tag 'locking-urgent-2020-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking fixes from Thomas Gleixner:
 "A set of fixes for lockdep, tracing and RCU:

   - Prevent recursion by using raw_cpu_* operations

   - Fixup the interrupt state in the cpu idle code to be consistent

   - Push rcu_idle_enter/exit() invocations deeper into the idle path so
     that the lock operations are inside the RCU watching sections

   - Move trace_cpu_idle() into generic code so it's called before RCU
     goes idle.

   - Handle raw_local_irq* vs. local_irq* operations correctly

   - Move the tracepoints out from under the lockdep recursion handling
     which turned out to be fragile and inconsistent"

* tag 'locking-urgent-2020-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  lockdep,trace: Expose tracepoints
  lockdep: Only trace IRQ edges
  mips: Implement arch_irqs_disabled()
  arm64: Implement arch_irqs_disabled()
  nds32: Implement arch_irqs_disabled()
  locking/lockdep: Cleanup
  x86/entry: Remove unused THUNKs
  cpuidle: Move trace_cpu_idle() into generic code
  cpuidle: Make CPUIDLE_FLAG_TLB_FLUSHED generic
  sched,idle,rcu: Push rcu_idle deeper into the idle path
  cpuidle: Fixup IRQ state
  lockdep: Use raw_cpu_*() for per-cpu variables

4 files changed, 64 insertions, 45 deletions

diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index b65909ae4e20..75895e6363b8 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -75,12 +75,13 @@ struct cpuidle_state {
 };
 
 /* Idle State Flags */
-#define CPUIDLE_FLAG_NONE       (0x00)
-#define CPUIDLE_FLAG_POLLING	BIT(0) /* polling state */
-#define CPUIDLE_FLAG_COUPLED	BIT(1) /* state applies to multiple cpus */
-#define CPUIDLE_FLAG_TIMER_STOP BIT(2) /* timer is stopped on this state */
-#define CPUIDLE_FLAG_UNUSABLE	BIT(3) /* avoid using this state */
-#define CPUIDLE_FLAG_OFF	BIT(4) /* disable this state by default */
+#define CPUIDLE_FLAG_NONE       	(0x00)
+#define CPUIDLE_FLAG_POLLING		BIT(0) /* polling state */
+#define CPUIDLE_FLAG_COUPLED		BIT(1) /* state applies to multiple cpus */
+#define CPUIDLE_FLAG_TIMER_STOP 	BIT(2) /* timer is stopped on this state */
+#define CPUIDLE_FLAG_UNUSABLE		BIT(3) /* avoid using this state */
+#define CPUIDLE_FLAG_OFF		BIT(4) /* disable this state by default */
+#define CPUIDLE_FLAG_TLB_FLUSHED	BIT(5) /* idle-state flushes TLBs */
 
 struct cpuidle_device_kobj;
 struct cpuidle_state_kobj;
diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h
index bd5c55755447..3ed4e8771b64 100644
--- a/include/linux/irqflags.h
+++ b/include/linux/irqflags.h
@@ -49,17 +49,18 @@ struct irqtrace_events {
 DECLARE_PER_CPU(int, hardirqs_enabled);
 DECLARE_PER_CPU(int, hardirq_context);
 
-  extern void trace_hardirqs_on_prepare(void);
-  extern void trace_hardirqs_off_finish(void);
-  extern void trace_hardirqs_on(void);
-  extern void trace_hardirqs_off(void);
-# define lockdep_hardirq_context()	(this_cpu_read(hardirq_context))
+extern void trace_hardirqs_on_prepare(void);
+extern void trace_hardirqs_off_finish(void);
+extern void trace_hardirqs_on(void);
+extern void trace_hardirqs_off(void);
+
+# define lockdep_hardirq_context()	(raw_cpu_read(hardirq_context))
 # define lockdep_softirq_context(p)	((p)->softirq_context)
 # define lockdep_hardirqs_enabled()	(this_cpu_read(hardirqs_enabled))
 # define lockdep_softirqs_enabled(p)	((p)->softirqs_enabled)
 # define lockdep_hardirq_enter()			\
 do {							\
-	if (this_cpu_inc_return(hardirq_context) == 1)	\
+	if (__this_cpu_inc_return(hardirq_context) == 1)\
 		current->hardirq_threaded = 0;		\
 } while (0)
 # define lockdep_hardirq_threaded()		\
@@ -68,7 +69,7 @@ do {						\
 } while (0)
 # define lockdep_hardirq_exit()			\
 do {						\
-	this_cpu_dec(hardirq_context);		\
+	__this_cpu_dec(hardirq_context);	\
 } while (0)
 # define lockdep_softirq_enter()		\
 do {						\
@@ -120,17 +121,17 @@ do {						\
 #else
 # define trace_hardirqs_on_prepare()		do { } while (0)
 # define trace_hardirqs_off_finish()		do { } while (0)
-# define trace_hardirqs_on()		do { } while (0)
-# define trace_hardirqs_off()		do { } while (0)
-# define lockdep_hardirq_context()	0
-# define lockdep_softirq_context(p)	0
-# define lockdep_hardirqs_enabled()	0
-# define lockdep_softirqs_enabled(p)	0
-# define lockdep_hardirq_enter()	do { } while (0)
-# define lockdep_hardirq_threaded()	do { } while (0)
-# define lockdep_hardirq_exit()		do { } while (0)
-# define lockdep_softirq_enter()	do { } while (0)
-# define lockdep_softirq_exit()		do { } while (0)
+# define trace_hardirqs_on()			do { } while (0)
+# define trace_hardirqs_off()			do { } while (0)
+# define lockdep_hardirq_context()		0
+# define lockdep_softirq_context(p)		0
+# define lockdep_hardirqs_enabled()		0
+# define lockdep_softirqs_enabled(p)		0
+# define lockdep_hardirq_enter()		do { } while (0)
+# define lockdep_hardirq_threaded()		do { } while (0)
+# define lockdep_hardirq_exit()			do { } while (0)
+# define lockdep_softirq_enter()		do { } while (0)
+# define lockdep_softirq_exit()			do { } while (0)
 # define lockdep_hrtimer_enter(__hrtimer)	false
 # define lockdep_hrtimer_exit(__context)	do { } while (0)
 # define lockdep_posixtimer_enter()		do { } while (0)
@@ -181,26 +182,33 @@ do {						\
  * if !TRACE_IRQFLAGS.
  */
 #ifdef CONFIG_TRACE_IRQFLAGS
-#define local_irq_enable() \
-	do { trace_hardirqs_on(); raw_local_irq_enable(); } while (0)
-#define local_irq_disable() \
-	do { raw_local_irq_disable(); trace_hardirqs_off(); } while (0)
+
+#define local_irq_enable()				\
+	do {						\
+		trace_hardirqs_on();			\
+		raw_local_irq_enable();			\
+	} while (0)
+
+#define local_irq_disable()				\
+	do {						\
+		bool was_disabled = raw_irqs_disabled();\
+		raw_local_irq_disable();		\
+		if (!was_disabled)			\
+			trace_hardirqs_off();		\
+	} while (0)
+
 #define local_irq_save(flags)				\
 	do {						\
 		raw_local_irq_save(flags);		\
-		trace_hardirqs_off();			\
+		if (!raw_irqs_disabled_flags(flags))	\
+			trace_hardirqs_off();		\
 	} while (0)
 
-
 #define local_irq_restore(flags)			\
 	do {						\
-		if (raw_irqs_disabled_flags(flags)) {	\
-			raw_local_irq_restore(flags);	\
-			trace_hardirqs_off();		\
-		} else {				\
+		if (!raw_irqs_disabled_flags(flags))	\
 			trace_hardirqs_on();		\
-			raw_local_irq_restore(flags);	\
-		}					\
+		raw_local_irq_restore(flags);		\
 	} while (0)
 
 #define safe_halt()				\
@@ -214,10 +222,7 @@ do {						\
 
 #define local_irq_enable()	do { raw_local_irq_enable(); } while (0)
 #define local_irq_disable()	do { raw_local_irq_disable(); } while (0)
-#define local_irq_save(flags)					\
-	do {							\
-		raw_local_irq_save(flags);			\
-	} while (0)
+#define local_irq_save(flags)	do { raw_local_irq_save(flags); } while (0)
 #define local_irq_restore(flags) do { raw_local_irq_restore(flags); } while (0)
 #define safe_halt()		do { raw_safe_halt(); } while (0)
 
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 62a382d1845b..6a584b3e5c74 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -535,19 +535,27 @@ do {									\
 DECLARE_PER_CPU(int, hardirqs_enabled);
 DECLARE_PER_CPU(int, hardirq_context);
 
+/*
+ * The below lockdep_assert_*() macros use raw_cpu_read() to access the above
+ * per-cpu variables. This is required because this_cpu_read() will potentially
+ * call into preempt/irq-disable and that obviously isn't right. This is also
+ * correct because when IRQs are enabled, it doesn't matter if we accidentally
+ * read the value from our previous CPU.
+ */
+
 #define lockdep_assert_irqs_enabled()					\
 do {									\
-	WARN_ON_ONCE(debug_locks && !this_cpu_read(hardirqs_enabled));	\
+	WARN_ON_ONCE(debug_locks && !raw_cpu_read(hardirqs_enabled));	\
 } while (0)
 
 #define lockdep_assert_irqs_disabled()					\
 do {									\
-	WARN_ON_ONCE(debug_locks && this_cpu_read(hardirqs_enabled));	\
+	WARN_ON_ONCE(debug_locks && raw_cpu_read(hardirqs_enabled));	\
 } while (0)
 
 #define lockdep_assert_in_irq()						\
 do {									\
-	WARN_ON_ONCE(debug_locks && !this_cpu_read(hardirq_context));	\
+	WARN_ON_ONCE(debug_locks && !raw_cpu_read(hardirq_context));	\
 } while (0)
 
 #define lockdep_assert_preemption_enabled()				\
@@ -555,7 +563,7 @@ do {									\
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_COUNT)	&&		\
 		     debug_locks			&&		\
 		     (preempt_count() != 0		||		\
-		      !this_cpu_read(hardirqs_enabled)));		\
+		      !raw_cpu_read(hardirqs_enabled)));		\
 } while (0)
 
 #define lockdep_assert_preemption_disabled()				\
@@ -563,7 +571,7 @@ do {									\
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_PREEMPT_COUNT)	&&		\
 		     debug_locks			&&		\
 		     (preempt_count() == 0		&&		\
-		      this_cpu_read(hardirqs_enabled)));		\
+		      raw_cpu_read(hardirqs_enabled)));			\
 } while (0)
 
 #else
diff --git a/include/linux/mmu_context.h b/include/linux/mmu_context.h
index c51a84132d7c..03dee12d2b61 100644
--- a/include/linux/mmu_context.h
+++ b/include/linux/mmu_context.h
@@ -3,10 +3,15 @@
 #define _LINUX_MMU_CONTEXT_H
 
 #include <asm/mmu_context.h>
+#include <asm/mmu.h>
 
 /* Architectures that care about IRQ state in switch_mm can override this. */
 #ifndef switch_mm_irqs_off
 # define switch_mm_irqs_off switch_mm
 #endif
 
+#ifndef leave_mm
+static inline void leave_mm(int cpu) { }
+#endif
+
 #endif