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>

10 files changed, 9 insertions, 78 deletions

diff --git a/arch/sparc64/kernel/smp.c b/arch/sparc64/kernel/smp.c
index f500b0618bb..c6d06362728 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 83abd5ae88a..da1b781b5e6 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 81ccd22e78d..04994fc8700 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 c499214b501..8c91d9b29a2 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 70ac4186f62..0268210ca16 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 6b015a6eefb..2b7228cb8c2 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 1a4cc5654de..91a7d29a79d 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 185f3467911..4bd63968400 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 587f8efb2e0..f0282fad632 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 86773e89dc1..e4c146f7c7e 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