[MIPS] Make support for weakly ordered LL/SC a config option.

None of weakly ordered processor supported in tree need this but it seems
like this could change ...
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -1190,8 +1190,19 @@ config SYS_HAS_CPU_RM9000
 config SYS_HAS_CPU_SB1
 	bool
 
+#
+# CPU may reorder R->R, R->W, W->R, W->W
+# Reordering beyond LL and SC is handled in WEAK_REORDERING_BEYOND_LLSC
+#
 config WEAK_ORDERING
 	bool
+
+#
+# CPU may reorder reads and writes beyond LL/SC
+# CPU may reorder R->LL, R->LL, W->LL, W->LL, R->SC, R->SC, W->SC, W->SC
+#
+config WEAK_REORDERING_BEYOND_LLSC
+	bool
 endmenu
 
 #

include/asm-mips/atomic.h

@@ -138,7 +138,7 @@ static __inline__ int atomic_add_return(int i, atomic_t * v)
 {
 	unsigned long result;
 
-	smp_mb();
+	smp_llsc_mb();
 
 	if (cpu_has_llsc && R10000_LLSC_WAR) {
 		unsigned long temp;
@@ -181,7 +181,7 @@ static __inline__ int atomic_add_return(int i, atomic_t * v)
 		raw_local_irq_restore(flags);
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return result;
 }
@@ -190,7 +190,7 @@ static __inline__ int atomic_sub_return(int i, atomic_t * v)
 {
 	unsigned long result;
 
-	smp_mb();
+	smp_llsc_mb();
 
 	if (cpu_has_llsc && R10000_LLSC_WAR) {
 		unsigned long temp;
@@ -233,7 +233,7 @@ static __inline__ int atomic_sub_return(int i, atomic_t * v)
 		raw_local_irq_restore(flags);
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return result;
 }
@@ -250,7 +250,7 @@ static __inline__ int atomic_sub_if_positive(int i, atomic_t * v)
 {
 	unsigned long result;
 
-	smp_mb();
+	smp_llsc_mb();
 
 	if (cpu_has_llsc && R10000_LLSC_WAR) {
 		unsigned long temp;
@@ -302,7 +302,7 @@ static __inline__ int atomic_sub_if_positive(int i, atomic_t * v)
 		raw_local_irq_restore(flags);
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return result;
 }
@@ -519,7 +519,7 @@ static __inline__ long atomic64_add_return(long i, atomic64_t * v)
 {
 	unsigned long result;
 
-	smp_mb();
+	smp_llsc_mb();
 
 	if (cpu_has_llsc && R10000_LLSC_WAR) {
 		unsigned long temp;
@@ -562,7 +562,7 @@ static __inline__ long atomic64_add_return(long i, atomic64_t * v)
 		raw_local_irq_restore(flags);
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return result;
 }
@@ -571,7 +571,7 @@ static __inline__ long atomic64_sub_return(long i, atomic64_t * v)
 {
 	unsigned long result;
 
-	smp_mb();
+	smp_llsc_mb();
 
 	if (cpu_has_llsc && R10000_LLSC_WAR) {
 		unsigned long temp;
@@ -614,7 +614,7 @@ static __inline__ long atomic64_sub_return(long i, atomic64_t * v)
 		raw_local_irq_restore(flags);
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return result;
 }
@@ -631,7 +631,7 @@ static __inline__ long atomic64_sub_if_positive(long i, atomic64_t * v)
 {
 	unsigned long result;
 
-	smp_mb();
+	smp_llsc_mb();
 
 	if (cpu_has_llsc && R10000_LLSC_WAR) {
 		unsigned long temp;
@@ -683,7 +683,7 @@ static __inline__ long atomic64_sub_if_positive(long i, atomic64_t * v)
 		raw_local_irq_restore(flags);
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return result;
 }
@@ -791,10 +791,11 @@ static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u)
  * atomic*_return operations are serializing but not the non-*_return
  * versions.
  */
-#define smp_mb__before_atomic_dec()	smp_mb()
-#define smp_mb__after_atomic_dec()	smp_mb()
-#define smp_mb__before_atomic_inc()	smp_mb()
-#define smp_mb__after_atomic_inc()	smp_mb()
+#define smp_mb__before_atomic_dec()	smp_llsc_mb()
+#define smp_mb__after_atomic_dec()	smp_llsc_mb()
+#define smp_mb__before_atomic_inc()	smp_llsc_mb()
+#define smp_mb__after_atomic_inc()	smp_llsc_mb()
 
 #include <asm-generic/atomic.h>
+
 #endif /* _ASM_ATOMIC_H */

include/asm-mips/barrier.h

@@ -121,6 +121,11 @@
 #else
 #define __WEAK_ORDERING_MB	"		\n"
 #endif
+#if defined(CONFIG_WEAK_REORDERING_BEYOND_LLSC) && defined(CONFIG_SMP)
+#define __WEAK_LLSC_MB		"       sync	\n"
+#else
+#define __WEAK_LLSC_MB		"		\n"
+#endif
 
 #define smp_mb()	__asm__ __volatile__(__WEAK_ORDERING_MB : : :"memory")
 #define smp_rmb()	__asm__ __volatile__(__WEAK_ORDERING_MB : : :"memory")
@@ -129,4 +134,8 @@
 #define set_mb(var, value) \
 	do { var = value; smp_mb(); } while (0)
 
+#define smp_llsc_mb()	__asm__ __volatile__(__WEAK_LLSC_MB : : :"memory")
+#define smp_llsc_rmb()	__asm__ __volatile__(__WEAK_LLSC_MB : : :"memory")
+#define smp_llsc_wmb()	__asm__ __volatile__(__WEAK_LLSC_MB : : :"memory")
+
 #endif /* __ASM_BARRIER_H */

include/asm-mips/bitops.h

@@ -38,8 +38,8 @@
 /*
  * clear_bit() doesn't provide any barrier for the compiler.
  */
-#define smp_mb__before_clear_bit()	smp_mb()
-#define smp_mb__after_clear_bit()	smp_mb()
+#define smp_mb__before_clear_bit()	smp_llsc_mb()
+#define smp_mb__after_clear_bit()	smp_llsc_mb()
 
 /*
  * set_bit - Atomically set a bit in memory
@@ -289,7 +289,7 @@ static inline int test_and_set_bit(unsigned long nr,
 		raw_local_irq_restore(flags);
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return res != 0;
 }
@@ -377,7 +377,7 @@ static inline int test_and_clear_bit(unsigned long nr,
 		raw_local_irq_restore(flags);
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return res != 0;
 }
@@ -445,7 +445,7 @@ static inline int test_and_change_bit(unsigned long nr,
 		raw_local_irq_restore(flags);
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return res != 0;
 }

include/asm-mips/futex.h

@@ -29,7 +29,7 @@
 		"	.set	mips3				\n"	\
 		"2:	sc	$1, %2				\n"	\
 		"	beqzl	$1, 1b				\n"	\
-		__WEAK_ORDERING_MB					\
+		__WEAK_LLSC_MB						\
 		"3:						\n"	\
 		"	.set	pop				\n"	\
 		"	.set	mips0				\n"	\
@@ -55,7 +55,7 @@
 		"	.set	mips3				\n"	\
 		"2:	sc	$1, %2				\n"	\
 		"	beqz	$1, 1b				\n"	\
-		__WEAK_ORDERING_MB					\
+		__WEAK_LLSC_MB						\
 		"3:						\n"	\
 		"	.set	pop				\n"	\
 		"	.set	mips0				\n"	\
@@ -152,7 +152,7 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
 		"	.set	mips3					\n"
 		"2:	sc	$1, %1					\n"
 		"	beqzl	$1, 1b					\n"
-		__WEAK_ORDERING_MB
+		__WEAK_LLSC_MB
 		"3:							\n"
 		"	.set	pop					\n"
 		"	.section .fixup,\"ax\"				\n"
@@ -179,7 +179,7 @@ futex_atomic_cmpxchg_inatomic(int __user *uaddr, int oldval, int newval)
 		"	.set	mips3					\n"
 		"2:	sc	$1, %1					\n"
 		"	beqz	$1, 1b					\n"
-		__WEAK_ORDERING_MB
+		__WEAK_LLSC_MB
 		"3:							\n"
 		"	.set	pop					\n"
 		"	.section .fixup,\"ax\"				\n"

include/asm-mips/spinlock.h

@@ -67,7 +67,7 @@ static inline void __raw_spin_lock(raw_spinlock_t *lock)
 		: "memory");
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 }
 
 static inline void __raw_spin_unlock(raw_spinlock_t *lock)
@@ -118,7 +118,7 @@ static inline unsigned int __raw_spin_trylock(raw_spinlock_t *lock)
 		: "memory");
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return res == 0;
 }
@@ -183,7 +183,7 @@ static inline void __raw_read_lock(raw_rwlock_t *rw)
 		: "memory");
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 }
 
 /* Note the use of sub, not subu which will make the kernel die with an
@@ -193,7 +193,7 @@ static inline void __raw_read_unlock(raw_rwlock_t *rw)
 {
 	unsigned int tmp;
 
-	smp_mb();
+	smp_llsc_mb();
 
 	if (R10000_LLSC_WAR) {
 		__asm__ __volatile__(
@@ -262,7 +262,7 @@ static inline void __raw_write_lock(raw_rwlock_t *rw)
 		: "memory");
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 }
 
 static inline void __raw_write_unlock(raw_rwlock_t *rw)
@@ -293,7 +293,7 @@ static inline int __raw_read_trylock(raw_rwlock_t *rw)
 		"	.set	reorder					\n"
 		"	beqzl	%1, 1b					\n"
 		"	 nop						\n"
-		__WEAK_ORDERING_MB
+		__WEAK_LLSC_MB
 		"	li	%2, 1					\n"
 		"2:							\n"
 		: "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
@@ -310,7 +310,7 @@ static inline int __raw_read_trylock(raw_rwlock_t *rw)
 		"	beqz	%1, 1b					\n"
 		"	 nop						\n"
 		"	.set	reorder					\n"
-		__WEAK_ORDERING_MB
+		__WEAK_LLSC_MB
 		"	li	%2, 1					\n"
 		"2:							\n"
 		: "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
@@ -336,7 +336,7 @@ static inline int __raw_write_trylock(raw_rwlock_t *rw)
 		"	sc	%1, %0					\n"
 		"	beqzl	%1, 1b					\n"
 		"	 nop						\n"
-		__WEAK_ORDERING_MB
+		__WEAK_LLSC_MB
 		"	li	%2, 1					\n"
 		"	.set	reorder					\n"
 		"2:							\n"
@@ -354,7 +354,7 @@ static inline int __raw_write_trylock(raw_rwlock_t *rw)
 		"	beqz	%1, 3f					\n"
 		"	 li	%2, 1					\n"
 		"2:							\n"
-		__WEAK_ORDERING_MB
+		__WEAK_LLSC_MB
 		"	.subsection 2					\n"
 		"3:	b	1b					\n"
 		"	 li	%2, 0					\n"

include/asm-mips/system.h

@@ -117,7 +117,7 @@ static inline unsigned long __xchg_u32(volatile int * m, unsigned int val)
 		raw_local_irq_restore(flags);	/* implies memory barrier  */
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return retval;
 }
@@ -165,7 +165,7 @@ static inline __u64 __xchg_u64(volatile __u64 * m, __u64 val)
 		raw_local_irq_restore(flags);	/* implies memory barrier  */
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return retval;
 }
@@ -246,7 +246,7 @@ static inline unsigned long __cmpxchg_u32(volatile int * m, unsigned long old,
 		raw_local_irq_restore(flags);	/* implies memory barrier  */
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return retval;
 }
@@ -352,7 +352,7 @@ static inline unsigned long __cmpxchg_u64(volatile int * m, unsigned long old,
 		raw_local_irq_restore(flags);	/* implies memory barrier  */
 	}
 
-	smp_mb();
+	smp_llsc_mb();
 
 	return retval;
 }