[SPARC64]: Inline membar()'s again.

Since GCC has to emit a call and a delay slot to the
out-of-line "membar" routines in arch/sparc64/lib/mb.S
it is much better to just do the necessary predicted
branch inline instead as:

	ba,pt	%xcc, 1f
	 membar	#whatever
1:

instead of the current:

	call	membar_foo
	 dslot

because this way GCC is not required to allocate a stack
frame if the function can be a leaf function.

This also makes this bug fix easier to backport to 2.4.x

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

2 files changed, 1 insertions, 74 deletions

diff --git a/arch/sparc64/lib/Makefile b/arch/sparc64/lib/Makefile
index 6201f104098..40dbeec7e5d 100644
--- a/arch/sparc64/lib/Makefile
+++ b/arch/sparc64/lib/Makefile
@@ -12,7 +12,7 @@ lib-y := PeeCeeI.o copy_page.o clear_page.o strlen.o strncmp.o \
 	 U1memcpy.o U1copy_from_user.o U1copy_to_user.o \
 	 U3memcpy.o U3copy_from_user.o U3copy_to_user.o U3patch.o \
 	 copy_in_user.o user_fixup.o memmove.o \
-	 mcount.o ipcsum.o rwsem.o xor.o find_bit.o delay.o mb.o
+	 mcount.o ipcsum.o rwsem.o xor.o find_bit.o delay.o
 
 lib-$(CONFIG_DEBUG_SPINLOCK) += debuglocks.o
 lib-$(CONFIG_HAVE_DEC_LOCK) += dec_and_lock.o
diff --git a/arch/sparc64/lib/mb.S b/arch/sparc64/lib/mb.S
deleted file mode 100644
index 4004f748619..00000000000
--- a/arch/sparc64/lib/mb.S
+++ /dev/null
@@ -1,73 +0,0 @@
-/* mb.S: Out of line memory barriers.
- *
- * Copyright (C) 2005 David S. Miller (davem@davemloft.net)
- */
-
-	/* These are here in an effort to more fully work around
-	 * Spitfire Errata #51.  Essentially, if a memory barrier
-	 * occurs soon after a mispredicted branch, the chip can stop
-	 * executing instructions until a trap occurs.  Therefore, if
-	 * interrupts are disabled, the chip can hang forever.
-	 *
-	 * It used to be believed that the memory barrier had to be
-	 * right in the delay slot, but a case has been traced
-	 * recently wherein the memory barrier was one instruction
-	 * after the branch delay slot and the chip still hung.  The
-	 * offending sequence was the following in sym_wakeup_done()
-	 * of the sym53c8xx_2 driver:
-	 *
-	 *	call	sym_ccb_from_dsa, 0
-	 *	 movge	%icc, 0, %l0
-	 *	brz,pn	%o0, .LL1303
-	 *	 mov	%o0, %l2
-	 *	membar	#LoadLoad
-	 *
-	 * The branch has to be mispredicted for the bug to occur.
-	 * Therefore, we put the memory barrier explicitly into a
-	 * "branch always, predicted taken" delay slot to avoid the
-	 * problem case.
-	 */
-
-	.text
-
-99:	retl
-	 nop
-
-	.globl	mb
-mb:	ba,pt	%xcc, 99b
-	 membar	#LoadLoad | #LoadStore | #StoreStore | #StoreLoad
-	.size	mb, .-mb
-
-	.globl	rmb
-rmb:	ba,pt	%xcc, 99b
-	 membar	#LoadLoad
-	.size	rmb, .-rmb
-
-	.globl	wmb
-wmb:	ba,pt	%xcc, 99b
-	 membar	#StoreStore
-	.size	wmb, .-wmb
-
-	.globl	membar_storeload
-membar_storeload:
-	ba,pt	%xcc, 99b
-	 membar	#StoreLoad
-	.size	membar_storeload, .-membar_storeload
-
-	.globl	membar_storeload_storestore
-membar_storeload_storestore:
-	ba,pt	%xcc, 99b
-	 membar	#StoreLoad | #StoreStore
-	.size	membar_storeload_storestore, .-membar_storeload_storestore
-
-	.globl	membar_storeload_loadload
-membar_storeload_loadload:
-	ba,pt	%xcc, 99b
-	 membar	#StoreLoad | #LoadLoad
-	.size	membar_storeload_loadload, .-membar_storeload_loadload
-
-	.globl	membar_storestore_loadstore
-membar_storestore_loadstore:
-	ba,pt	%xcc, 99b
-	 membar	#StoreStore | #LoadStore
-	.size	membar_storestore_loadstore, .-membar_storestore_loadstore