s390/bitops,atomic: add missing memory barriers

When reworking the bitops and atomic ops I missed that those instructions
that got atomic behaviour only perform a "specific-operand-serialization"
instead of a full "serialization".
The compare-and-swap instruction used before performs a full serialization
before and after the instruction is executed, which means it has full
memory barrier semantics.
In order to give the new bitops and atomic ops functions also full memory
barrier semantics add a "bcr 14,0" before and after each of those new
instructions which performs full serialization as well.

This restores memory barrier semantics for bitops and atomic ops functions
which return values, like e.g. atomic_add_return(), but not for functions
which do not return a value, like e.g. atomic_add().
This is consistent to other architectures and what common code requires.

Cc: stable@vger.kernel.org # v3.13+
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 23 insertions, 18 deletions

diff --git a/arch/s390/include/asm/bitops.h b/arch/s390/include/asm/bitops.h
index ec5ef891db6b..520542477678 100644
--- a/arch/s390/include/asm/bitops.h
+++ b/arch/s390/include/asm/bitops.h
@@ -47,14 +47,18 @@
 
 #include <linux/typecheck.h>
 #include <linux/compiler.h>
+#include <asm/barrier.h>
+
+#define __BITOPS_NO_BARRIER	"\n"
 
 #ifndef CONFIG_64BIT
 
 #define __BITOPS_OR		"or"
 #define __BITOPS_AND		"nr"
 #define __BITOPS_XOR		"xr"
+#define __BITOPS_BARRIER	"\n"
 
-#define __BITOPS_LOOP(__addr, __val, __op_string)		\
+#define __BITOPS_LOOP(__addr, __val, __op_string, __barrier)	\
 ({								\
 	unsigned long __old, __new;				\
 								\
@@ -67,7 +71,7 @@
 		"	jl	0b"				\
 		: "=&d" (__old), "=&d" (__new), "+Q" (*(__addr))\
 		: "d" (__val)					\
-		: "cc");					\
+		: "cc", "memory");				\
 	__old;							\
 })
 
@@ -78,17 +82,20 @@
 #define __BITOPS_OR		"laog"
 #define __BITOPS_AND		"lang"
 #define __BITOPS_XOR		"laxg"
+#define __BITOPS_BARRIER	"bcr	14,0\n"
 
-#define __BITOPS_LOOP(__addr, __val, __op_string)		\
+#define __BITOPS_LOOP(__addr, __val, __op_string, __barrier)	\
 ({								\
 	unsigned long __old;					\
 								\
 	typecheck(unsigned long *, (__addr));			\
 	asm volatile(						\
+		__barrier					\
 		__op_string "	%0,%2,%1\n"			\
+		__barrier					\
 		: "=d" (__old),	"+Q" (*(__addr))		\
 		: "d" (__val)					\
-		: "cc");					\
+		: "cc", "memory");				\
 	__old;							\
 })
 
@@ -97,8 +104,9 @@
 #define __BITOPS_OR		"ogr"
 #define __BITOPS_AND		"ngr"
 #define __BITOPS_XOR		"xgr"
+#define __BITOPS_BARRIER	"\n"
 
-#define __BITOPS_LOOP(__addr, __val, __op_string)		\
+#define __BITOPS_LOOP(__addr, __val, __op_string, __barrier)	\
 ({								\
 	unsigned long __old, __new;				\
 								\
@@ -111,7 +119,7 @@
 		"	jl	0b"				\
 		: "=&d" (__old), "=&d" (__new), "+Q" (*(__addr))\
 		: "d" (__val)					\
-		: "cc");					\
+		: "cc", "memory");				\
 	__old;							\
 })
 
@@ -149,12 +157,12 @@ static inline void set_bit(unsigned long nr, volatile unsigned long *ptr)
 			"oi	%0,%b1\n"
 			: "+Q" (*caddr)
 			: "i" (1 << (nr & 7))
-			: "cc");
+			: "cc", "memory");
 		return;
 	}
 #endif
 	mask = 1UL << (nr & (BITS_PER_LONG - 1));
-	__BITOPS_LOOP(addr, mask, __BITOPS_OR);
+	__BITOPS_LOOP(addr, mask, __BITOPS_OR, __BITOPS_NO_BARRIER);
 }
 
 static inline void clear_bit(unsigned long nr, volatile unsigned long *ptr)
@@ -170,12 +178,12 @@ static inline void clear_bit(unsigned long nr, volatile unsigned long *ptr)
 			"ni	%0,%b1\n"
 			: "+Q" (*caddr)
 			: "i" (~(1 << (nr & 7)))
-			: "cc");
+			: "cc", "memory");
 		return;
 	}
 #endif
 	mask = ~(1UL << (nr & (BITS_PER_LONG - 1)));
-	__BITOPS_LOOP(addr, mask, __BITOPS_AND);
+	__BITOPS_LOOP(addr, mask, __BITOPS_AND, __BITOPS_NO_BARRIER);
 }
 
 static inline void change_bit(unsigned long nr, volatile unsigned long *ptr)
@@ -191,12 +199,12 @@ static inline void change_bit(unsigned long nr, volatile unsigned long *ptr)
 			"xi	%0,%b1\n"
 			: "+Q" (*caddr)
 			: "i" (1 << (nr & 7))
-			: "cc");
+			: "cc", "memory");
 		return;
 	}
 #endif
 	mask = 1UL << (nr & (BITS_PER_LONG - 1));
-	__BITOPS_LOOP(addr, mask, __BITOPS_XOR);
+	__BITOPS_LOOP(addr, mask, __BITOPS_XOR, __BITOPS_NO_BARRIER);
 }
 
 static inline int
@@ -206,8 +214,7 @@ test_and_set_bit(unsigned long nr, volatile unsigned long *ptr)
 	unsigned long old, mask;
 
 	mask = 1UL << (nr & (BITS_PER_LONG - 1));
-	old = __BITOPS_LOOP(addr, mask, __BITOPS_OR);
-	barrier();
+	old = __BITOPS_LOOP(addr, mask, __BITOPS_OR, __BITOPS_BARRIER);
 	return (old & mask) != 0;
 }
 
@@ -218,8 +225,7 @@ test_and_clear_bit(unsigned long nr, volatile unsigned long *ptr)
 	unsigned long old, mask;
 
 	mask = ~(1UL << (nr & (BITS_PER_LONG - 1)));
-	old = __BITOPS_LOOP(addr, mask, __BITOPS_AND);
-	barrier();
+	old = __BITOPS_LOOP(addr, mask, __BITOPS_AND, __BITOPS_BARRIER);
 	return (old & ~mask) != 0;
 }
 
@@ -230,8 +236,7 @@ test_and_change_bit(unsigned long nr, volatile unsigned long *ptr)
 	unsigned long old, mask;
 
 	mask = 1UL << (nr & (BITS_PER_LONG - 1));
-	old = __BITOPS_LOOP(addr, mask, __BITOPS_XOR);
-	barrier();
+	old = __BITOPS_LOOP(addr, mask, __BITOPS_XOR, __BITOPS_BARRIER);
 	return (old & mask) != 0;
 }