MIPS: asm: local: add barriers for Loongson

Somehow these LL/SC usages are not taken care of, breaking Loongson
builds. Add the SYNCs appropriately.
Signed-off-by: Wang Xuerui <git@xen0n.name>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: Huacai Chen <chenhc@lemote.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: <stable@vger.kernel.org> # v5.5+

arch/mips/include/asm/local.h

@@ -37,6 +37,7 @@ static __inline__ long local_add_return(long i, local_t * l)
 		__asm__ __volatile__(
 		"	.set	push					\n"
 		"	.set	arch=r4000				\n"
+			__SYNC(full, loongson3_war) "			\n"
 		"1:"	__LL	"%1, %2		# local_add_return	\n"
 		"	addu	%0, %1, %3				\n"
 			__SC	"%0, %2					\n"
@@ -52,6 +53,7 @@ static __inline__ long local_add_return(long i, local_t * l)
 		__asm__ __volatile__(
 		"	.set	push					\n"
 		"	.set	"MIPS_ISA_ARCH_LEVEL"			\n"
+			__SYNC(full, loongson3_war) "			\n"
 		"1:"	__LL	"%1, %2		# local_add_return	\n"
 		"	addu	%0, %1, %3				\n"
 			__SC	"%0, %2					\n"
@@ -84,6 +86,7 @@ static __inline__ long local_sub_return(long i, local_t * l)
 		__asm__ __volatile__(
 		"	.set	push					\n"
 		"	.set	arch=r4000				\n"
+			__SYNC(full, loongson3_war) "			\n"
 		"1:"	__LL	"%1, %2		# local_sub_return	\n"
 		"	subu	%0, %1, %3				\n"
 			__SC	"%0, %2					\n"
@@ -99,6 +102,7 @@ static __inline__ long local_sub_return(long i, local_t * l)
 		__asm__ __volatile__(
 		"	.set	push					\n"
 		"	.set	"MIPS_ISA_ARCH_LEVEL"			\n"
+			__SYNC(full, loongson3_war) "			\n"
 		"1:"	__LL	"%1, %2		# local_sub_return	\n"
 		"	subu	%0, %1, %3				\n"
 			__SC	"%0, %2					\n"