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>

3 files changed, 0 insertions, 57 deletions

diff --git a/arch/sparc64/lib/atomic.S b/arch/sparc64/lib/atomic.S
index 70ac418..0268210 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 6b015a6..2b7228c 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 1a4cc56..91a7d29 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: