diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 0d14f51d0002..a84c24d894aa 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1403,6 +1403,21 @@ config LOONGSON3_ENHANCEMENT
 	  please say 'N' here. If you want a high-performance kernel to run on
 	  new Loongson 3 machines only, please say 'Y' here.
 
+config CPU_LOONGSON3_WORKAROUNDS
+	bool "Old Loongson 3 LLSC Workarounds"
+	default y if SMP
+	depends on CPU_LOONGSON3
+	help
+	  Loongson 3 processors have the llsc issues which require workarounds.
+	  Without workarounds the system may hang unexpectedly.
+
+	  Newer Loongson 3 will fix these issues and no workarounds are needed.
+	  The workarounds have no significant side effect on them but may
+	  decrease the performance of the system so this option should be
+	  disabled unless the kernel is intended to be run on old systems.
+
+	  If unsure, please say Y.
+
 config CPU_LOONGSON2E
 	bool "Loongson 2E"
 	depends on SYS_HAS_CPU_LOONGSON2E
diff --git a/arch/mips/include/asm/atomic.h b/arch/mips/include/asm/atomic.h
index 43fcd35e2957..94096299fc56 100644
--- a/arch/mips/include/asm/atomic.h
+++ b/arch/mips/include/asm/atomic.h
@@ -58,6 +58,7 @@ static __inline__ void atomic_##op(int i, atomic_t * v)			      \
 	if (kernel_uses_llsc) {						      \
 		int temp;						      \
 									      \
+		loongson_llsc_mb();					      \
 		__asm__ __volatile__(					      \
 		"	.set	push					\n"   \
 		"	.set	"MIPS_ISA_LEVEL"			\n"   \
@@ -85,6 +86,7 @@ static __inline__ int atomic_##op##_return_relaxed(int i, atomic_t * v)	      \
 	if (kernel_uses_llsc) {						      \
 		int temp;						      \
 									      \
+		loongson_llsc_mb();					      \
 		__asm__ __volatile__(					      \
 		"	.set	push					\n"   \
 		"	.set	"MIPS_ISA_LEVEL"			\n"   \
@@ -118,6 +120,7 @@ static __inline__ int atomic_fetch_##op##_relaxed(int i, atomic_t * v)	      \
 	if (kernel_uses_llsc) {						      \
 		int temp;						      \
 									      \
+		loongson_llsc_mb();					      \
 		__asm__ __volatile__(					      \
 		"	.set	push					\n"   \
 		"	.set	"MIPS_ISA_LEVEL"			\n"   \
@@ -256,6 +259,7 @@ static __inline__ void atomic64_##op(long i, atomic64_t * v)		      \
 	if (kernel_uses_llsc) {						      \
 		long temp;						      \
 									      \
+		loongson_llsc_mb();					      \
 		__asm__ __volatile__(					      \
 		"	.set	push					\n"   \
 		"	.set	"MIPS_ISA_LEVEL"			\n"   \
@@ -283,6 +287,7 @@ static __inline__ long atomic64_##op##_return_relaxed(long i, atomic64_t * v) \
 	if (kernel_uses_llsc) {						      \
 		long temp;						      \
 									      \
+		loongson_llsc_mb();					      \
 		__asm__ __volatile__(					      \
 		"	.set	push					\n"   \
 		"	.set	"MIPS_ISA_LEVEL"			\n"   \
@@ -316,6 +321,7 @@ static __inline__ long atomic64_fetch_##op##_relaxed(long i, atomic64_t * v)  \
 	if (kernel_uses_llsc) {						      \
 		long temp;						      \
 									      \
+		loongson_llsc_mb();					      \
 		__asm__ __volatile__(					      \
 		"	.set	push					\n"   \
 		"	.set	"MIPS_ISA_LEVEL"			\n"   \
diff --git a/arch/mips/include/asm/barrier.h b/arch/mips/include/asm/barrier.h
index a5eb1bb199a7..b7f6ac5e513c 100644
--- a/arch/mips/include/asm/barrier.h
+++ b/arch/mips/include/asm/barrier.h
@@ -222,6 +222,42 @@
 #define __smp_mb__before_atomic()	__smp_mb__before_llsc()
 #define __smp_mb__after_atomic()	smp_llsc_mb()
 
+/*
+ * Some Loongson 3 CPUs have a bug wherein execution of a memory access (load,
+ * store or pref) in between an ll & sc can cause the sc instruction to
+ * erroneously succeed, breaking atomicity. Whilst it's unusual to write code
+ * containing such sequences, this bug bites harder than we might otherwise
+ * expect due to reordering & speculation:
+ *
+ * 1) A memory access appearing prior to the ll in program order may actually
+ *    be executed after the ll - this is the reordering case.
+ *
+ *    In order to avoid this we need to place a memory barrier (ie. a sync
+ *    instruction) prior to every ll instruction, in between it & any earlier
+ *    memory access instructions. Many of these cases are already covered by
+ *    smp_mb__before_llsc() but for the remaining cases, typically ones in
+ *    which multiple CPUs may operate on a memory location but ordering is not
+ *    usually guaranteed, we use loongson_llsc_mb() below.
+ *
+ *    This reordering case is fixed by 3A R2 CPUs, ie. 3A2000 models and later.
+ *
+ * 2) If a conditional branch exists between an ll & sc with a target outside
+ *    of the ll-sc loop, for example an exit upon value mismatch in cmpxchg()
+ *    or similar, then misprediction of the branch may allow speculative
+ *    execution of memory accesses from outside of the ll-sc loop.
+ *
+ *    In order to avoid this we need a memory barrier (ie. a sync instruction)
+ *    at each affected branch target, for which we also use loongson_llsc_mb()
+ *    defined below.
+ *
+ *    This case affects all current Loongson 3 CPUs.
+ */
+#ifdef CONFIG_CPU_LOONGSON3_WORKAROUNDS /* Loongson-3's LLSC workaround */
+#define loongson_llsc_mb()	__asm__ __volatile__(__WEAK_LLSC_MB : : :"memory")
+#else
+#define loongson_llsc_mb()	do { } while (0)
+#endif
+
 #include <asm-generic/barrier.h>
 
 #endif /* __ASM_BARRIER_H */
diff --git a/arch/mips/include/asm/bitops.h b/arch/mips/include/asm/bitops.h
index c4675957b21b..830c93a010c3 100644
--- a/arch/mips/include/asm/bitops.h
+++ b/arch/mips/include/asm/bitops.h
@@ -69,6 +69,7 @@ static inline void set_bit(unsigned long nr, volatile unsigned long *addr)
 		: "ir" (1UL << bit), GCC_OFF_SMALL_ASM() (*m));
 #if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6)
 	} else if (kernel_uses_llsc && __builtin_constant_p(bit)) {
+		loongson_llsc_mb();
 		do {
 			__asm__ __volatile__(
 			"	" __LL "%0, %1		# set_bit	\n"
@@ -79,6 +80,7 @@ static inline void set_bit(unsigned long nr, volatile unsigned long *addr)
 		} while (unlikely(!temp));
 #endif /* CONFIG_CPU_MIPSR2 || CONFIG_CPU_MIPSR6 */
 	} else if (kernel_uses_llsc) {
+		loongson_llsc_mb();
 		do {
 			__asm__ __volatile__(
 			"	.set	push				\n"
@@ -123,6 +125,7 @@ static inline void clear_bit(unsigned long nr, volatile unsigned long *addr)
 		: "ir" (~(1UL << bit)));
 #if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6)
 	} else if (kernel_uses_llsc && __builtin_constant_p(bit)) {
+		loongson_llsc_mb();
 		do {
 			__asm__ __volatile__(
 			"	" __LL "%0, %1		# clear_bit	\n"
@@ -133,6 +136,7 @@ static inline void clear_bit(unsigned long nr, volatile unsigned long *addr)
 		} while (unlikely(!temp));
 #endif /* CONFIG_CPU_MIPSR2 || CONFIG_CPU_MIPSR6 */
 	} else if (kernel_uses_llsc) {
+		loongson_llsc_mb();
 		do {
 			__asm__ __volatile__(
 			"	.set	push				\n"
@@ -193,6 +197,7 @@ static inline void change_bit(unsigned long nr, volatile unsigned long *addr)
 		unsigned long *m = ((unsigned long *) addr) + (nr >> SZLONG_LOG);
 		unsigned long temp;
 
+		loongson_llsc_mb();
 		do {
 			__asm__ __volatile__(
 			"	.set	push				\n"
diff --git a/arch/mips/include/asm/futex.h b/arch/mips/include/asm/futex.h
index c14d798f3888..b83b0397462d 100644
--- a/arch/mips/include/asm/futex.h
+++ b/arch/mips/include/asm/futex.h
@@ -50,6 +50,7 @@
 		  "i" (-EFAULT)						\
 		: "memory");						\
 	} else if (cpu_has_llsc) {					\
+		loongson_llsc_mb();					\
 		__asm__ __volatile__(					\
 		"	.set	push				\n"	\
 		"	.set	noat				\n"	\
@@ -163,6 +164,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 		  "i" (-EFAULT)
 		: "memory");
 	} else if (cpu_has_llsc) {
+		loongson_llsc_mb();
 		__asm__ __volatile__(
 		"# futex_atomic_cmpxchg_inatomic			\n"
 		"	.set	push					\n"
@@ -192,6 +194,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 		: GCC_OFF_SMALL_ASM() (*uaddr), "Jr" (oldval), "Jr" (newval),
 		  "i" (-EFAULT)
 		: "memory");
+		loongson_llsc_mb();
 	} else
 		return -ENOSYS;
 
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 57933fc8fd98..910851c62db3 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -228,6 +228,7 @@ static inline void set_pte(pte_t *ptep, pte_t pteval)
 			: [buddy] "+m" (buddy->pte), [tmp] "=&r" (tmp)
 			: [global] "r" (page_global));
 		} else if (kernel_uses_llsc) {
+			loongson_llsc_mb();
 			__asm__ __volatile__ (
 			"	.set	push				\n"
 			"	.set	"MIPS_ISA_ARCH_LEVEL"		\n"
@@ -242,6 +243,7 @@ static inline void set_pte(pte_t *ptep, pte_t pteval)
 			"	.set	pop				\n"
 			: [buddy] "+m" (buddy->pte), [tmp] "=&r" (tmp)
 			: [global] "r" (page_global));
+			loongson_llsc_mb();
 		}
 #else /* !CONFIG_SMP */
 		if (pte_none(*buddy))
diff --git a/arch/mips/loongson64/Platform b/arch/mips/loongson64/Platform
index 0fce4608aa88..c1a4d4dc4665 100644
--- a/arch/mips/loongson64/Platform
+++ b/arch/mips/loongson64/Platform
@@ -23,6 +23,29 @@ ifdef CONFIG_CPU_LOONGSON2F_WORKAROUNDS
 endif
 
 cflags-$(CONFIG_CPU_LOONGSON3)	+= -Wa,--trap
+
+#
+# Some versions of binutils, not currently mainline as of 2019/02/04, support
+# an -mfix-loongson3-llsc flag which emits a sync prior to each ll instruction
+# to work around a CPU bug (see loongson_llsc_mb() in asm/barrier.h for a
+# description).
+#
+# We disable this in order to prevent the assembler meddling with the
+# instruction that labels refer to, ie. if we label an ll instruction:
+#
+# 1: ll v0, 0(a0)
+#
+# ...then with the assembler fix applied the label may actually point at a sync
+# instruction inserted by the assembler, and if we were using the label in an
+# exception table the table would no longer contain the address of the ll
+# instruction.
+#
+# Avoid this by explicitly disabling that assembler behaviour. If upstream
+# binutils does not merge support for the flag then we can revisit & remove
+# this later - for now it ensures vendor toolchains don't cause problems.
+#
+cflags-$(CONFIG_CPU_LOONGSON3)	+= $(call as-option,-Wa$(comma)-mno-fix-loongson3-llsc,)
+
 #
 # binutils from v2.25 on and gcc starting from v4.9.0 treat -march=loongson3a
 # as MIPS64 R2; older versions as just R1.  This leaves the possibility open
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index 37b1cb246332..65b6e85447b1 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -932,6 +932,8 @@ build_get_pgd_vmalloc64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
 		 * to mimic that here by taking a load/istream page
 		 * fault.
 		 */
+		if (IS_ENABLED(CONFIG_CPU_LOONGSON3_WORKAROUNDS))
+			uasm_i_sync(p, 0);
 		UASM_i_LA(p, ptr, (unsigned long)tlb_do_page_fault_0);
 		uasm_i_jr(p, ptr);
 
@@ -1646,6 +1648,8 @@ static void
 iPTE_LW(u32 **p, unsigned int pte, unsigned int ptr)
 {
 #ifdef CONFIG_SMP
+	if (IS_ENABLED(CONFIG_CPU_LOONGSON3_WORKAROUNDS))
+		uasm_i_sync(p, 0);
 # ifdef CONFIG_PHYS_ADDR_T_64BIT
 	if (cpu_has_64bits)
 		uasm_i_lld(p, pte, 0, ptr);
@@ -2259,6 +2263,8 @@ static void build_r4000_tlb_load_handler(void)
 #endif
 
 	uasm_l_nopage_tlbl(&l, p);
+	if (IS_ENABLED(CONFIG_CPU_LOONGSON3_WORKAROUNDS))
+		uasm_i_sync(&p, 0);
 	build_restore_work_registers(&p);
 #ifdef CONFIG_CPU_MICROMIPS
 	if ((unsigned long)tlb_do_page_fault_0 & 1) {
@@ -2313,6 +2319,8 @@ static void build_r4000_tlb_store_handler(void)
 #endif
 
 	uasm_l_nopage_tlbs(&l, p);
+	if (IS_ENABLED(CONFIG_CPU_LOONGSON3_WORKAROUNDS))
+		uasm_i_sync(&p, 0);
 	build_restore_work_registers(&p);
 #ifdef CONFIG_CPU_MICROMIPS
 	if ((unsigned long)tlb_do_page_fault_1 & 1) {
@@ -2368,6 +2376,8 @@ static void build_r4000_tlb_modify_handler(void)
 #endif
 
 	uasm_l_nopage_tlbm(&l, p);
+	if (IS_ENABLED(CONFIG_CPU_LOONGSON3_WORKAROUNDS))
+		uasm_i_sync(&p, 0);
 	build_restore_work_registers(&p);
 #ifdef CONFIG_CPU_MICROMIPS
 	if ((unsigned long)tlb_do_page_fault_1 & 1) {