From f948666de517cf8ebef7cb2c9b2d669dec4bfe2e Mon Sep 17 00:00:00 2001
From: Marco Elver <elver@google.com>
Date: Tue, 30 Nov 2021 12:44:22 +0100
Subject: [PATCH] locking/barriers, kcsan: Add instrumentation for barriers

Adds the required KCSAN instrumentation for barriers if CONFIG_SMP.
KCSAN supports modeling the effects of:

	smp_mb()
	smp_rmb()
	smp_wmb()
	smp_store_release()

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 include/asm-generic/barrier.h | 29 +++++++++++++++--------------
 include/linux/spinlock.h      |  2 +-
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
index 640f094..27a9c9e 100644
--- a/include/asm-generic/barrier.h
+++ b/include/asm-generic/barrier.h
@@ -14,6 +14,7 @@
 #ifndef __ASSEMBLY__
 
 #include <linux/compiler.h>
+#include <linux/kcsan-checks.h>
 #include <asm/rwonce.h>
 
 #ifndef nop
@@ -62,15 +63,15 @@
 #ifdef CONFIG_SMP
 
 #ifndef smp_mb
-#define smp_mb()	__smp_mb()
+#define smp_mb()	do { kcsan_mb(); __smp_mb(); } while (0)
 #endif
 
 #ifndef smp_rmb
-#define smp_rmb()	__smp_rmb()
+#define smp_rmb()	do { kcsan_rmb(); __smp_rmb(); } while (0)
 #endif
 
 #ifndef smp_wmb
-#define smp_wmb()	__smp_wmb()
+#define smp_wmb()	do { kcsan_wmb(); __smp_wmb(); } while (0)
 #endif
 
 #else	/* !CONFIG_SMP */
@@ -123,19 +124,19 @@ do {									\
 #ifdef CONFIG_SMP
 
 #ifndef smp_store_mb
-#define smp_store_mb(var, value)  __smp_store_mb(var, value)
+#define smp_store_mb(var, value)  do { kcsan_mb(); __smp_store_mb(var, value); } while (0)
 #endif
 
 #ifndef smp_mb__before_atomic
-#define smp_mb__before_atomic()	__smp_mb__before_atomic()
+#define smp_mb__before_atomic()	do { kcsan_mb(); __smp_mb__before_atomic(); } while (0)
 #endif
 
 #ifndef smp_mb__after_atomic
-#define smp_mb__after_atomic()	__smp_mb__after_atomic()
+#define smp_mb__after_atomic()	do { kcsan_mb(); __smp_mb__after_atomic(); } while (0)
 #endif
 
 #ifndef smp_store_release
-#define smp_store_release(p, v) __smp_store_release(p, v)
+#define smp_store_release(p, v) do { kcsan_release(); __smp_store_release(p, v); } while (0)
 #endif
 
 #ifndef smp_load_acquire
@@ -178,13 +179,13 @@ do {									\
 #endif	/* CONFIG_SMP */
 
 /* Barriers for virtual machine guests when talking to an SMP host */
-#define virt_mb() __smp_mb()
-#define virt_rmb() __smp_rmb()
-#define virt_wmb() __smp_wmb()
-#define virt_store_mb(var, value) __smp_store_mb(var, value)
-#define virt_mb__before_atomic() __smp_mb__before_atomic()
-#define virt_mb__after_atomic()	__smp_mb__after_atomic()
-#define virt_store_release(p, v) __smp_store_release(p, v)
+#define virt_mb() do { kcsan_mb(); __smp_mb(); } while (0)
+#define virt_rmb() do { kcsan_rmb(); __smp_rmb(); } while (0)
+#define virt_wmb() do { kcsan_wmb(); __smp_wmb(); } while (0)
+#define virt_store_mb(var, value) do { kcsan_mb(); __smp_store_mb(var, value); } while (0)
+#define virt_mb__before_atomic() do { kcsan_mb(); __smp_mb__before_atomic(); } while (0)
+#define virt_mb__after_atomic()	do { kcsan_mb(); __smp_mb__after_atomic(); } while (0)
+#define virt_store_release(p, v) do { kcsan_release(); __smp_store_release(p, v); } while (0)
 #define virt_load_acquire(p) __smp_load_acquire(p)
 
 /**
diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
index b4e5ca2..5c0c517 100644
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -171,7 +171,7 @@ do {									\
  * Architectures that can implement ACQUIRE better need to take care.
  */
 #ifndef smp_mb__after_spinlock
-#define smp_mb__after_spinlock()	do { } while (0)
+#define smp_mb__after_spinlock()	kcsan_mb()
 #endif
 
 #ifdef CONFIG_DEBUG_SPINLOCK
-- 
2.7.4