From: David S. Miller <davem@davemloft.net>
Date: Sat, 15 Nov 2008 21:33:25 +0000 (-0800)
Subject: sparc64: Stop using memory barriers for atomics and locks.
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=293666b7a17cb7a389fc274980439212386a19c4;p=openwrt%2Fstaging%2Fblogic.git

sparc64: Stop using memory barriers for atomics and locks.

The kernel always executes in the TSO memory model now,
so none of this stuff is necessary any more.

With helpful feedback from Nick Piggin.

Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/arch/sparc/include/asm/atomic_64.h b/arch/sparc/include/asm/atomic_64.h
index 2c71ec4a3b18..5982c5ae7f07 100644
--- a/arch/sparc/include/asm/atomic_64.h
+++ b/arch/sparc/include/asm/atomic_64.h
@@ -112,17 +112,10 @@ static inline int atomic64_add_unless(atomic64_t *v, long a, long u)
 #define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
 
 /* Atomic operations are already serializing */
-#ifdef CONFIG_SMP
-#define smp_mb__before_atomic_dec()	membar_storeload_loadload();
-#define smp_mb__after_atomic_dec()	membar_storeload_storestore();
-#define smp_mb__before_atomic_inc()	membar_storeload_loadload();
-#define smp_mb__after_atomic_inc()	membar_storeload_storestore();
-#else
 #define smp_mb__before_atomic_dec()	barrier()
 #define smp_mb__after_atomic_dec()	barrier()
 #define smp_mb__before_atomic_inc()	barrier()
 #define smp_mb__after_atomic_inc()	barrier()
-#endif
 
 #include <asm-generic/atomic.h>
 #endif /* !(__ARCH_SPARC64_ATOMIC__) */
diff --git a/arch/sparc/include/asm/bitops_64.h b/arch/sparc/include/asm/bitops_64.h
index bb87b8080220..e72ac9cdfb98 100644
--- a/arch/sparc/include/asm/bitops_64.h
+++ b/arch/sparc/include/asm/bitops_64.h
@@ -23,13 +23,8 @@ extern void change_bit(unsigned long nr, volatile unsigned long *addr);
 
 #include <asm-generic/bitops/non-atomic.h>
 
-#ifdef CONFIG_SMP
-#define smp_mb__before_clear_bit()	membar_storeload_loadload()
-#define smp_mb__after_clear_bit()	membar_storeload_storestore()
-#else
 #define smp_mb__before_clear_bit()	barrier()
 #define smp_mb__after_clear_bit()	barrier()
-#endif
 
 #include <asm-generic/bitops/ffz.h>
 #include <asm-generic/bitops/__ffs.h>
diff --git a/arch/sparc/include/asm/spinlock_64.h b/arch/sparc/include/asm/spinlock_64.h
index fbac9d00744a..c4d274d330e9 100644
--- a/arch/sparc/include/asm/spinlock_64.h
+++ b/arch/sparc/include/asm/spinlock_64.h
@@ -33,12 +33,10 @@ static inline void __raw_spin_lock(raw_spinlock_t *lock)
 
 	__asm__ __volatile__(
 "1:	ldstub		[%1], %0\n"
-"	membar		#StoreLoad | #StoreStore\n"
 "	brnz,pn		%0, 2f\n"
 "	 nop\n"
 "	.subsection	2\n"
 "2:	ldub		[%1], %0\n"
-"	membar		#LoadLoad\n"
 "	brnz,pt		%0, 2b\n"
 "	 nop\n"
 "	ba,a,pt		%%xcc, 1b\n"
@@ -54,7 +52,6 @@ static inline int __raw_spin_trylock(raw_spinlock_t *lock)
 
 	__asm__ __volatile__(
 "	ldstub		[%1], %0\n"
-"	membar		#StoreLoad | #StoreStore"
 	: "=r" (result)
 	: "r" (lock)
 	: "memory");
@@ -65,7 +62,6 @@ static inline int __raw_spin_trylock(raw_spinlock_t *lock)
 static inline void __raw_spin_unlock(raw_spinlock_t *lock)
 {
 	__asm__ __volatile__(
-"	membar		#StoreStore | #LoadStore\n"
 "	stb		%%g0, [%0]"
 	: /* No outputs */
 	: "r" (lock)
@@ -78,14 +74,12 @@ static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long fla
 
 	__asm__ __volatile__(
 "1:	ldstub		[%2], %0\n"
-"	membar		#StoreLoad | #StoreStore\n"
 "	brnz,pn		%0, 2f\n"
 "	 nop\n"
 "	.subsection	2\n"
 "2:	rdpr		%%pil, %1\n"
 "	wrpr		%3, %%pil\n"
 "3:	ldub		[%2], %0\n"
-"	membar		#LoadLoad\n"
 "	brnz,pt		%0, 3b\n"
 "	 nop\n"
 "	ba,pt		%%xcc, 1b\n"
@@ -108,12 +102,10 @@ static void inline __read_lock(raw_rwlock_t *lock)
 "4:	 add		%0, 1, %1\n"
 "	cas		[%2], %0, %1\n"
 "	cmp		%0, %1\n"
-"	membar		#StoreLoad | #StoreStore\n"
 "	bne,pn		%%icc, 1b\n"
 "	 nop\n"
 "	.subsection	2\n"
 "2:	ldsw		[%2], %0\n"
-"	membar		#LoadLoad\n"
 "	brlz,pt		%0, 2b\n"
 "	 nop\n"
 "	ba,a,pt		%%xcc, 4b\n"
@@ -134,7 +126,6 @@ static int inline __read_trylock(raw_rwlock_t *lock)
 "	add		%0, 1, %1\n"
 "	cas		[%2], %0, %1\n"
 "	cmp		%0, %1\n"
-"	membar		#StoreLoad | #StoreStore\n"
 "	bne,pn		%%icc, 1b\n"
 "	 mov		1, %0\n"
 "2:"
@@ -150,7 +141,6 @@ static void inline __read_unlock(raw_rwlock_t *lock)
 	unsigned long tmp1, tmp2;
 
 	__asm__ __volatile__(
-"	membar	#StoreLoad | #LoadLoad\n"
 "1:	lduw	[%2], %0\n"
 "	sub	%0, 1, %1\n"
 "	cas	[%2], %0, %1\n"
@@ -174,12 +164,10 @@ static void inline __write_lock(raw_rwlock_t *lock)
 "4:	 or		%0, %3, %1\n"
 "	cas		[%2], %0, %1\n"
 "	cmp		%0, %1\n"
-"	membar		#StoreLoad | #StoreStore\n"
 "	bne,pn		%%icc, 1b\n"
 "	 nop\n"
 "	.subsection	2\n"
 "2:	lduw		[%2], %0\n"
-"	membar		#LoadLoad\n"
 "	brnz,pt		%0, 2b\n"
 "	 nop\n"
 "	ba,a,pt		%%xcc, 4b\n"
@@ -192,7 +180,6 @@ static void inline __write_lock(raw_rwlock_t *lock)
 static void inline __write_unlock(raw_rwlock_t *lock)
 {
 	__asm__ __volatile__(
-"	membar		#LoadStore | #StoreStore\n"
 "	stw		%%g0, [%0]"
 	: /* no outputs */
 	: "r" (lock)
@@ -212,7 +199,6 @@ static int inline __write_trylock(raw_rwlock_t *lock)
 "	 or		%0, %4, %1\n"
 "	cas		[%3], %0, %1\n"
 "	cmp		%0, %1\n"
-"	membar		#StoreLoad | #StoreStore\n"
 "	bne,pn		%%icc, 1b\n"
 "	 nop\n"
 "	mov		1, %2\n"
diff --git a/arch/sparc/include/asm/system_64.h b/arch/sparc/include/asm/system_64.h
index 8759f2a1b837..7554ad39b5af 100644
--- a/arch/sparc/include/asm/system_64.h
+++ b/arch/sparc/include/asm/system_64.h
@@ -59,20 +59,9 @@ do {	__asm__ __volatile__("ba,pt	%%xcc, 1f\n\t" \
 			     : : : "memory"); \
 } while (0)
 
-#define mb()	\
-	membar_safe("#LoadLoad | #LoadStore | #StoreStore | #StoreLoad")
-#define rmb()	\
-	membar_safe("#LoadLoad")
-#define wmb()	\
-	membar_safe("#StoreStore")
-#define membar_storeload() \
-	membar_safe("#StoreLoad")
-#define membar_storeload_storestore() \
-	membar_safe("#StoreLoad | #StoreStore")
-#define membar_storeload_loadload() \
-	membar_safe("#StoreLoad | #LoadLoad")
-#define membar_storestore_loadstore() \
-	membar_safe("#StoreStore | #LoadStore")
+#define mb()	membar_safe("#StoreLoad")
+#define rmb()	__asm__ __volatile__("":::"memory")
+#define wmb()	__asm__ __volatile__("":::"memory")
 
 #endif
 
@@ -80,20 +69,20 @@ do {	__asm__ __volatile__("ba,pt	%%xcc, 1f\n\t" \
 
 #define read_barrier_depends()		do { } while(0)
 #define set_mb(__var, __value) \
-	do { __var = __value; membar_storeload_storestore(); } while(0)
+	do { __var = __value; membar_safe("#StoreLoad"); } while(0)
 
 #ifdef CONFIG_SMP
 #define smp_mb()	mb()
 #define smp_rmb()	rmb()
 #define smp_wmb()	wmb()
-#define smp_read_barrier_depends()	read_barrier_depends()
 #else
 #define smp_mb()	__asm__ __volatile__("":::"memory")
 #define smp_rmb()	__asm__ __volatile__("":::"memory")
 #define smp_wmb()	__asm__ __volatile__("":::"memory")
-#define smp_read_barrier_depends()	do { } while(0)
 #endif
 
+#define smp_read_barrier_depends()	do { } while(0)
+
 #define flushi(addr)	__asm__ __volatile__ ("flush %0" : : "r" (addr) : "memory")
 
 #define flushw_all()	__asm__ __volatile__("flushw")
@@ -209,14 +198,12 @@ static inline unsigned long xchg32(__volatile__ unsigned int *m, unsigned int va
 	unsigned long tmp1, tmp2;
 
 	__asm__ __volatile__(
-"	membar		#StoreLoad | #LoadLoad\n"
 "	mov		%0, %1\n"
 "1:	lduw		[%4], %2\n"
 "	cas		[%4], %2, %0\n"
 "	cmp		%2, %0\n"
 "	bne,a,pn	%%icc, 1b\n"
 "	 mov		%1, %0\n"
-"	membar		#StoreLoad | #StoreStore\n"
 	: "=&r" (val), "=&r" (tmp1), "=&r" (tmp2)
 	: "0" (val), "r" (m)
 	: "cc", "memory");
@@ -228,14 +215,12 @@ static inline unsigned long xchg64(__volatile__ unsigned long *m, unsigned long
 	unsigned long tmp1, tmp2;
 
 	__asm__ __volatile__(
-"	membar		#StoreLoad | #LoadLoad\n"
 "	mov		%0, %1\n"
 "1:	ldx		[%4], %2\n"
 "	casx		[%4], %2, %0\n"
 "	cmp		%2, %0\n"
 "	bne,a,pn	%%xcc, 1b\n"
 "	 mov		%1, %0\n"
-"	membar		#StoreLoad | #StoreStore\n"
 	: "=&r" (val), "=&r" (tmp1), "=&r" (tmp2)
 	: "0" (val), "r" (m)
 	: "cc", "memory");
@@ -272,9 +257,7 @@ extern void die_if_kernel(char *str, struct pt_regs *regs) __attribute__ ((noret
 static inline unsigned long
 __cmpxchg_u32(volatile int *m, int old, int new)
 {
-	__asm__ __volatile__("membar #StoreLoad | #LoadLoad\n"
-			     "cas [%2], %3, %0\n\t"
-			     "membar #StoreLoad | #StoreStore"
+	__asm__ __volatile__("cas [%2], %3, %0"
 			     : "=&r" (new)
 			     : "0" (new), "r" (m), "r" (old)
 			     : "memory");
@@ -285,9 +268,7 @@ __cmpxchg_u32(volatile int *m, int old, int new)
 static inline unsigned long
 __cmpxchg_u64(volatile long *m, unsigned long old, unsigned long new)
 {
-	__asm__ __volatile__("membar #StoreLoad | #LoadLoad\n"
-			     "casx [%2], %3, %0\n\t"
-			     "membar #StoreLoad | #StoreStore"
+	__asm__ __volatile__("casx [%2], %3, %0"
 			     : "=&r" (new)
 			     : "0" (new), "r" (m), "r" (old)
 			     : "memory");
diff --git a/arch/sparc/include/asm/tsb.h b/arch/sparc/include/asm/tsb.h
index 76e4299dd9bc..83c571d8c8a7 100644
--- a/arch/sparc/include/asm/tsb.h
+++ b/arch/sparc/include/asm/tsb.h
@@ -50,8 +50,6 @@
 #define TSB_TAG_INVALID_BIT	46
 #define TSB_TAG_INVALID_HIGH	(1 << (TSB_TAG_INVALID_BIT - 32))
 
-#define TSB_MEMBAR	membar	#StoreStore
-
 /* Some cpus support physical address quad loads.  We want to use
  * those if possible so we don't need to hard-lock the TSB mapping
  * into the TLB.  We encode some instruction patching in order to
@@ -128,13 +126,11 @@ extern struct tsb_phys_patch_entry __tsb_phys_patch, __tsb_phys_patch_end;
 	cmp	REG1, REG2;		\
 	bne,pn	%icc, 99b;		\
 	 nop;				\
-	TSB_MEMBAR
 
 #define TSB_WRITE(TSB, TTE, TAG) \
 	add	TSB, 0x8, TSB;   \
 	TSB_STORE(TSB, TTE);     \
 	sub	TSB, 0x8, TSB;   \
-	TSB_MEMBAR;              \
 	TSB_STORE(TSB, TAG);
 
 #define KTSB_LOAD_QUAD(TSB, REG) \
@@ -153,13 +149,11 @@ extern struct tsb_phys_patch_entry __tsb_phys_patch, __tsb_phys_patch_end;
 	cmp	REG1, REG2;		\
 	bne,pn	%icc, 99b;		\
 	 nop;				\
-	TSB_MEMBAR
 
 #define KTSB_WRITE(TSB, TTE, TAG) \
 	add	TSB, 0x8, TSB;   \
 	stxa	TTE, [TSB] ASI_N;     \
 	sub	TSB, 0x8, TSB;   \
-	TSB_MEMBAR;              \
 	stxa	TAG, [TSB] ASI_N;
 
 	/* Do a kernel page table walk.  Leaves physical PTE pointer in
diff --git a/arch/sparc64/kernel/smp.c b/arch/sparc64/kernel/smp.c
index f500b0618bb0..c6d06362728c 100644
--- a/arch/sparc64/kernel/smp.c
+++ b/arch/sparc64/kernel/smp.c
@@ -163,7 +163,7 @@ static inline long get_delta (long *rt, long *master)
 	for (i = 0; i < NUM_ITERS; i++) {
 		t0 = tick_ops->get_tick();
 		go[MASTER] = 1;
-		membar_storeload();
+		membar_safe("#StoreLoad");
 		while (!(tm = go[SLAVE]))
 			rmb();
 		go[SLAVE] = 0;
@@ -257,7 +257,7 @@ static void smp_synchronize_one_tick(int cpu)
 
 	/* now let the client proceed into his loop */
 	go[MASTER] = 0;
-	membar_storeload();
+	membar_safe("#StoreLoad");
 
 	spin_lock_irqsave(&itc_sync_lock, flags);
 	{
@@ -267,7 +267,7 @@ static void smp_synchronize_one_tick(int cpu)
 			go[MASTER] = 0;
 			wmb();
 			go[SLAVE] = tick_ops->get_tick();
-			membar_storeload();
+			membar_safe("#StoreLoad");
 		}
 	}
 	spin_unlock_irqrestore(&itc_sync_lock, flags);
@@ -1122,7 +1122,6 @@ void smp_capture(void)
 		       smp_processor_id());
 #endif
 		penguins_are_doing_time = 1;
-		membar_storestore_loadstore();
 		atomic_inc(&smp_capture_registry);
 		smp_cross_call(&xcall_capture, 0, 0, 0);
 		while (atomic_read(&smp_capture_registry) != ncpus)
@@ -1142,7 +1141,7 @@ void smp_release(void)
 		       smp_processor_id());
 #endif
 		penguins_are_doing_time = 0;
-		membar_storeload_storestore();
+		membar_safe("#StoreLoad");
 		atomic_dec(&smp_capture_registry);
 	}
 }
@@ -1161,7 +1160,7 @@ void smp_penguin_jailcell(int irq, struct pt_regs *regs)
 	__asm__ __volatile__("flushw");
 	prom_world(1);
 	atomic_inc(&smp_capture_registry);
-	membar_storeload_storestore();
+	membar_safe("#StoreLoad");
 	while (penguins_are_doing_time)
 		rmb();
 	atomic_dec(&smp_capture_registry);
diff --git a/arch/sparc64/kernel/trampoline.S b/arch/sparc64/kernel/trampoline.S
index 83abd5ae88a4..da1b781b5e65 100644
--- a/arch/sparc64/kernel/trampoline.S
+++ b/arch/sparc64/kernel/trampoline.S
@@ -109,7 +109,6 @@ startup_continue:
 	 */
 	sethi		%hi(prom_entry_lock), %g2
 1:	ldstub		[%g2 + %lo(prom_entry_lock)], %g1
-	membar		#StoreLoad | #StoreStore
 	brnz,pn		%g1, 1b
 	 nop
 
@@ -214,7 +213,6 @@ startup_continue:
 
 	sethi		%hi(prom_entry_lock), %g2
 	stb		%g0, [%g2 + %lo(prom_entry_lock)]
-	membar		#StoreStore | #StoreLoad
 
 	ba,pt		%xcc, after_lock_tlb
 	 nop
@@ -330,7 +328,6 @@ after_lock_tlb:
 
 	sethi		%hi(prom_entry_lock), %g2
 1:	ldstub		[%g2 + %lo(prom_entry_lock)], %g1
-	membar		#StoreLoad | #StoreStore
 	brnz,pn		%g1, 1b
 	 nop
 
@@ -394,7 +391,6 @@ after_lock_tlb:
 
 3:	sethi		%hi(prom_entry_lock), %g2
 	stb		%g0, [%g2 + %lo(prom_entry_lock)]
-	membar		#StoreStore | #StoreLoad
 
 	ldx		[%l0], %g6
 	ldx		[%g6 + TI_TASK], %g4
diff --git a/arch/sparc64/kernel/traps.c b/arch/sparc64/kernel/traps.c
index 81ccd22e78d4..04994fc8700d 100644
--- a/arch/sparc64/kernel/traps.c
+++ b/arch/sparc64/kernel/traps.c
@@ -1371,7 +1371,6 @@ static int cheetah_fix_ce(unsigned long physaddr)
 	__asm__ __volatile__("ldxa	[%0] %3, %%g0\n\t"
 			     "ldxa	[%1] %3, %%g0\n\t"
 			     "casxa	[%2] %3, %%g0, %%g0\n\t"
-			     "membar	#StoreLoad | #StoreStore\n\t"
 			     "ldxa	[%0] %3, %%g0\n\t"
 			     "ldxa	[%1] %3, %%g0\n\t"
 			     "membar	#Sync"
diff --git a/arch/sparc64/kernel/tsb.S b/arch/sparc64/kernel/tsb.S
index c499214b501d..8c91d9b29a2f 100644
--- a/arch/sparc64/kernel/tsb.S
+++ b/arch/sparc64/kernel/tsb.S
@@ -317,7 +317,7 @@ tsb_flush:
 	srlx	%g1, 32, %o3
 	andcc	%o3, %g2, %g0
 	bne,pn	%icc, 1b
-	 membar	#LoadLoad
+	 nop
 	cmp	%g1, %o1
 	mov	1, %o3
 	bne,pt	%xcc, 2f
@@ -327,7 +327,7 @@ tsb_flush:
 	bne,pn	%xcc, 1b
 	 nop
 2:	retl
-	 TSB_MEMBAR
+	 nop
 	.size	tsb_flush, .-tsb_flush
 
 	/* Reload MMU related context switch state at
@@ -478,7 +478,7 @@ copy_tsb:		/* %o0=old_tsb_base, %o1=old_tsb_size
 	 nop
 
 	retl
-	 TSB_MEMBAR
+	 nop
 	.size		copy_tsb, .-copy_tsb
 
 	/* Set the invalid bit in all TSB entries.  */
diff --git a/arch/sparc64/lib/atomic.S b/arch/sparc64/lib/atomic.S
index 70ac4186f62b..0268210ca168 100644
--- a/arch/sparc64/lib/atomic.S
+++ b/arch/sparc64/lib/atomic.S
@@ -43,29 +43,10 @@ atomic_sub: /* %o0 = decrement, %o1 = atomic_ptr */
 2:	BACKOFF_SPIN(%o2, %o3, 1b)
 	.size	atomic_sub, .-atomic_sub
 
-	/* On SMP we need to use memory barriers to ensure
-	 * correct memory operation ordering, nop these out
-	 * for uniprocessor.
-	 */
-#ifdef CONFIG_SMP
-
-#define ATOMIC_PRE_BARRIER	membar #StoreLoad | #LoadLoad;
-#define ATOMIC_POST_BARRIER	\
-	ba,pt %xcc, 80b;	\
-	membar #StoreLoad | #StoreStore
-
-80:	retl
-	 nop
-#else
-#define ATOMIC_PRE_BARRIER
-#define ATOMIC_POST_BARRIER
-#endif
-
 	.globl	atomic_add_ret
 	.type	atomic_add_ret,#function
 atomic_add_ret: /* %o0 = increment, %o1 = atomic_ptr */
 	BACKOFF_SETUP(%o2)
-	ATOMIC_PRE_BARRIER
 1:	lduw	[%o1], %g1
 	add	%g1, %o0, %g7
 	cas	[%o1], %g1, %g7
@@ -73,7 +54,6 @@ atomic_add_ret: /* %o0 = increment, %o1 = atomic_ptr */
 	bne,pn	%icc, 2f
 	 add	%g7, %o0, %g7
 	sra	%g7, 0, %o0
-	ATOMIC_POST_BARRIER
 	retl
 	 nop
 2:	BACKOFF_SPIN(%o2, %o3, 1b)
@@ -83,7 +63,6 @@ atomic_add_ret: /* %o0 = increment, %o1 = atomic_ptr */
 	.type	atomic_sub_ret,#function
 atomic_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */
 	BACKOFF_SETUP(%o2)
-	ATOMIC_PRE_BARRIER
 1:	lduw	[%o1], %g1
 	sub	%g1, %o0, %g7
 	cas	[%o1], %g1, %g7
@@ -91,7 +70,6 @@ atomic_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */
 	bne,pn	%icc, 2f
 	 sub	%g7, %o0, %g7
 	sra	%g7, 0, %o0
-	ATOMIC_POST_BARRIER
 	retl
 	 nop
 2:	BACKOFF_SPIN(%o2, %o3, 1b)
@@ -131,7 +109,6 @@ atomic64_sub: /* %o0 = decrement, %o1 = atomic_ptr */
 	.type	atomic64_add_ret,#function
 atomic64_add_ret: /* %o0 = increment, %o1 = atomic_ptr */
 	BACKOFF_SETUP(%o2)
-	ATOMIC_PRE_BARRIER
 1:	ldx	[%o1], %g1
 	add	%g1, %o0, %g7
 	casx	[%o1], %g1, %g7
@@ -139,7 +116,6 @@ atomic64_add_ret: /* %o0 = increment, %o1 = atomic_ptr */
 	bne,pn	%xcc, 2f
 	 add	%g7, %o0, %g7
 	mov	%g7, %o0
-	ATOMIC_POST_BARRIER
 	retl
 	 nop
 2:	BACKOFF_SPIN(%o2, %o3, 1b)
@@ -149,7 +125,6 @@ atomic64_add_ret: /* %o0 = increment, %o1 = atomic_ptr */
 	.type	atomic64_sub_ret,#function
 atomic64_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */
 	BACKOFF_SETUP(%o2)
-	ATOMIC_PRE_BARRIER
 1:	ldx	[%o1], %g1
 	sub	%g1, %o0, %g7
 	casx	[%o1], %g1, %g7
@@ -157,7 +132,6 @@ atomic64_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */
 	bne,pn	%xcc, 2f
 	 sub	%g7, %o0, %g7
 	mov	%g7, %o0
-	ATOMIC_POST_BARRIER
 	retl
 	 nop
 2:	BACKOFF_SPIN(%o2, %o3, 1b)
diff --git a/arch/sparc64/lib/bitops.S b/arch/sparc64/lib/bitops.S
index 6b015a6eefb5..2b7228cb8c22 100644
--- a/arch/sparc64/lib/bitops.S
+++ b/arch/sparc64/lib/bitops.S
@@ -8,29 +8,10 @@
 
 	.text
 
-	/* On SMP we need to use memory barriers to ensure
-	 * correct memory operation ordering, nop these out
-	 * for uniprocessor.
-	 */
-
-#ifdef CONFIG_SMP
-#define BITOP_PRE_BARRIER	membar #StoreLoad | #LoadLoad
-#define BITOP_POST_BARRIER	\
-	ba,pt	%xcc, 80b;	\
-	membar #StoreLoad | #StoreStore
-
-80:	retl
-	 nop
-#else
-#define BITOP_PRE_BARRIER
-#define BITOP_POST_BARRIER
-#endif
-
 	.globl	test_and_set_bit
 	.type	test_and_set_bit,#function
 test_and_set_bit:	/* %o0=nr, %o1=addr */
 	BACKOFF_SETUP(%o3)
-	BITOP_PRE_BARRIER
 	srlx	%o0, 6, %g1
 	mov	1, %o2
 	sllx	%g1, 3, %g3
@@ -45,7 +26,6 @@ test_and_set_bit:	/* %o0=nr, %o1=addr */
 	 and	%g7, %o2, %g2
 	clr	%o0
 	movrne	%g2, 1, %o0
-	BITOP_POST_BARRIER
 	retl
 	 nop
 2:	BACKOFF_SPIN(%o3, %o4, 1b)
@@ -55,7 +35,6 @@ test_and_set_bit:	/* %o0=nr, %o1=addr */
 	.type	test_and_clear_bit,#function
 test_and_clear_bit:	/* %o0=nr, %o1=addr */
 	BACKOFF_SETUP(%o3)
-	BITOP_PRE_BARRIER
 	srlx	%o0, 6, %g1
 	mov	1, %o2
 	sllx	%g1, 3, %g3
@@ -70,7 +49,6 @@ test_and_clear_bit:	/* %o0=nr, %o1=addr */
 	 and	%g7, %o2, %g2
 	clr	%o0
 	movrne	%g2, 1, %o0
-	BITOP_POST_BARRIER
 	retl
 	 nop
 2:	BACKOFF_SPIN(%o3, %o4, 1b)
@@ -80,7 +58,6 @@ test_and_clear_bit:	/* %o0=nr, %o1=addr */
 	.type	test_and_change_bit,#function
 test_and_change_bit:	/* %o0=nr, %o1=addr */
 	BACKOFF_SETUP(%o3)
-	BITOP_PRE_BARRIER
 	srlx	%o0, 6, %g1
 	mov	1, %o2
 	sllx	%g1, 3, %g3
@@ -95,7 +72,6 @@ test_and_change_bit:	/* %o0=nr, %o1=addr */
 	 and	%g7, %o2, %g2
 	clr	%o0
 	movrne	%g2, 1, %o0
-	BITOP_POST_BARRIER
 	retl
 	 nop
 2:	BACKOFF_SPIN(%o3, %o4, 1b)
diff --git a/arch/sparc64/lib/rwsem.S b/arch/sparc64/lib/rwsem.S
index 1a4cc5654de4..91a7d29a79d5 100644
--- a/arch/sparc64/lib/rwsem.S
+++ b/arch/sparc64/lib/rwsem.S
@@ -17,7 +17,6 @@ __down_read:
 	bne,pn		%icc, 1b
 	 add		%g7, 1, %g7
 	cmp		%g7, 0
-	membar		#StoreLoad | #StoreStore
 	bl,pn		%icc, 3f
 	 nop
 2:
@@ -42,7 +41,6 @@ __down_read_trylock:
 	cmp		%g1, %g7
 	bne,pn		%icc, 1b
 	 mov		1, %o1
-	membar		#StoreLoad | #StoreStore
 2:	retl
 	 mov		%o1, %o0
 	.size		__down_read_trylock, .-__down_read_trylock
@@ -58,7 +56,6 @@ __down_write:
 	cmp		%g3, %g7
 	bne,pn		%icc, 1b
 	 cmp		%g7, 0
-	membar		#StoreLoad | #StoreStore
 	bne,pn		%icc, 3f
 	 nop
 2:	retl
@@ -85,7 +82,6 @@ __down_write_trylock:
 	cmp		%g3, %g7
 	bne,pn		%icc, 1b
 	 mov		1, %o1
-	membar		#StoreLoad | #StoreStore
 2:	retl
 	 mov		%o1, %o0
 	.size		__down_write_trylock, .-__down_write_trylock
@@ -99,7 +95,6 @@ __up_read:
 	cmp		%g1, %g7
 	bne,pn		%icc, 1b
 	 cmp		%g7, 0
-	membar		#StoreLoad | #StoreStore
 	bl,pn		%icc, 3f
 	 nop
 2:	retl
@@ -129,7 +124,6 @@ __up_write:
 	bne,pn		%icc, 1b
 	 sub		%g7, %g1, %g7
 	cmp		%g7, 0
-	membar		#StoreLoad | #StoreStore
 	bl,pn		%icc, 3f
 	 nop
 2:
@@ -155,7 +149,6 @@ __downgrade_write:
 	bne,pn		%icc, 1b
 	 sub		%g7, %g1, %g7
 	cmp		%g7, 0
-	membar		#StoreLoad | #StoreStore
 	bl,pn		%icc, 3f
 	 nop
 2:
diff --git a/arch/sparc64/mm/init.c b/arch/sparc64/mm/init.c
index 185f34679110..4bd63968400d 100644
--- a/arch/sparc64/mm/init.c
+++ b/arch/sparc64/mm/init.c
@@ -214,7 +214,6 @@ static inline void set_dcache_dirty(struct page *page, int this_cpu)
 			     "or	%%g1, %0, %%g1\n\t"
 			     "casx	[%2], %%g7, %%g1\n\t"
 			     "cmp	%%g7, %%g1\n\t"
-			     "membar	#StoreLoad | #StoreStore\n\t"
 			     "bne,pn	%%xcc, 1b\n\t"
 			     " nop"
 			     : /* no outputs */
@@ -236,7 +235,6 @@ static inline void clear_dcache_dirty_cpu(struct page *page, unsigned long cpu)
 			     " andn	%%g7, %1, %%g1\n\t"
 			     "casx	[%2], %%g7, %%g1\n\t"
 			     "cmp	%%g7, %%g1\n\t"
-			     "membar	#StoreLoad | #StoreStore\n\t"
 			     "bne,pn	%%xcc, 1b\n\t"
 			     " nop\n"
 			     "2:"
diff --git a/arch/sparc64/mm/tsb.c b/arch/sparc64/mm/tsb.c
index 587f8efb2e05..f0282fad632a 100644
--- a/arch/sparc64/mm/tsb.c
+++ b/arch/sparc64/mm/tsb.c
@@ -41,10 +41,8 @@ void flush_tsb_kernel_range(unsigned long start, unsigned long end)
 					      KERNEL_TSB_NENTRIES);
 		struct tsb *ent = &swapper_tsb[hash];
 
-		if (tag_compare(ent->tag, v)) {
+		if (tag_compare(ent->tag, v))
 			ent->tag = (1UL << TSB_TAG_INVALID_BIT);
-			membar_storeload_storestore();
-		}
 	}
 }
 
diff --git a/arch/sparc64/mm/ultra.S b/arch/sparc64/mm/ultra.S
index 86773e89dc1b..e4c146f7c7e9 100644
--- a/arch/sparc64/mm/ultra.S
+++ b/arch/sparc64/mm/ultra.S
@@ -125,7 +125,6 @@ __spitfire_flush_tlb_mm_slow:
 	.align		32
 	.globl		__flush_icache_page
 __flush_icache_page:	/* %o0 = phys_page */
-	membar		#StoreStore
 	srlx		%o0, PAGE_SHIFT, %o0
 	sethi		%uhi(PAGE_OFFSET), %g1
 	sllx		%o0, PAGE_SHIFT, %o0
@@ -507,7 +506,6 @@ xcall_fetch_glob_regs:
 	sllx		%g2, TRAP_BLOCK_SZ_SHIFT, %g2
 	add		%g7, %g2, %g7
 	ldx		[%g7 + TRAP_PER_CPU_THREAD], %g3
-	membar		#StoreStore
 	stx		%g3, [%g1 + GR_SNAP_THREAD]
 	retry