diff --git a/arch/sh/mm/cache-sh4.c b/arch/sh/mm/cache-sh4.c
index c036c2b4ac2b..2203bd6aadb3 100644
--- a/arch/sh/mm/cache-sh4.c
+++ b/arch/sh/mm/cache-sh4.c
@@ -269,6 +269,11 @@ static inline void flush_icache_all(void)
 	ccr |= CCR_CACHE_ICI;
 	ctrl_outl(ccr, CCR);
 
+	/*
+	 * back_to_P1() will take care of the barrier for us, don't add
+	 * another one!
+	 */
+
 	back_to_P1();
 	local_irq_restore(flags);
 }
diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 775f86cd3fe8..364181f27b79 100644
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -369,12 +369,13 @@ void flush_tlb_all(void)
 	 * Flush all the TLB.
 	 *
 	 * Write to the MMU control register's bit:
-	 * 	TF-bit for SH-3, TI-bit for SH-4.
+	 *	TF-bit for SH-3, TI-bit for SH-4.
 	 *      It's same position, bit #2.
 	 */
 	local_irq_save(flags);
 	status = ctrl_inl(MMUCR);
-	status |= 0x04;		
+	status |= 0x04;
 	ctrl_outl(status, MMUCR);
+	ctrl_barrier();
 	local_irq_restore(flags);
 }
diff --git a/include/asm-sh/mmu_context.h b/include/asm-sh/mmu_context.h
index 6760d064bd02..87678ba8d6b6 100644
--- a/include/asm-sh/mmu_context.h
+++ b/include/asm-sh/mmu_context.h
@@ -174,9 +174,7 @@ static inline void enable_mmu(void)
 {
 	/* Enable MMU */
 	ctrl_outl(MMU_CONTROL_INIT, MMUCR);
-
-	/* The manual suggests doing some nops after turning on the MMU */
-	__asm__ __volatile__ ("nop;nop;nop;nop;nop;nop;nop;nop\n\t");
+	ctrl_barrier();
 
 	if (mmu_context_cache == NO_CONTEXT)
 		mmu_context_cache = MMU_CONTEXT_FIRST_VERSION;
@@ -191,7 +189,8 @@ static inline void disable_mmu(void)
 	cr = ctrl_inl(MMUCR);
 	cr &= ~MMU_CONTROL_INIT;
 	ctrl_outl(cr, MMUCR);
-	__asm__ __volatile__ ("nop;nop;nop;nop;nop;nop;nop;nop\n\t");
+
+	ctrl_barrier();
 }
 #else
 /*
diff --git a/include/asm-sh/system.h b/include/asm-sh/system.h
index eb4902ed920a..1630a5411e5f 100644
--- a/include/asm-sh/system.h
+++ b/include/asm-sh/system.h
@@ -67,8 +67,17 @@ static inline void sched_cacheflush(void)
 {
 }
 
-#define nop() __asm__ __volatile__ ("nop")
-
+#ifdef CONFIG_CPU_SH4A
+#define __icbi()			\
+{					\
+	unsigned long __addr;		\
+	__addr = 0xa8000000;		\
+	__asm__ __volatile__(		\
+		"icbi   %0\n\t"		\
+		: /* no output */	\
+		: "m" (__m(__addr)));	\
+}
+#endif
 
 #define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
 
@@ -84,15 +93,31 @@ static __inline__ unsigned long tas(volatile int *m)
 
 extern void __xchg_called_with_bad_pointer(void);
 
+/*
+ * A brief note on ctrl_barrier(), the control register write barrier.
+ *
+ * Legacy SH cores typically require a sequence of 8 nops after
+ * modification of a control register in order for the changes to take
+ * effect. On newer cores (like the sh4a and sh5) this is accomplished
+ * with icbi.
+ *
+ * Also note that on sh4a in the icbi case we can forego a synco for the
+ * write barrier, as it's not necessary for control registers.
+ *
+ * Historically we have only done this type of barrier for the MMUCR, but
+ * it's also necessary for the CCR, so we make it generic here instead.
+ */
 #ifdef CONFIG_CPU_SH4A
-#define mb()	__asm__ __volatile__ ("synco": : :"memory")
-#define rmb()	mb()
-#define wmb()	__asm__ __volatile__ ("synco": : :"memory")
+#define mb()		__asm__ __volatile__ ("synco": : :"memory")
+#define rmb()		mb()
+#define wmb()		__asm__ __volatile__ ("synco": : :"memory")
+#define ctrl_barrier()	__icbi()
 #define read_barrier_depends()	do { } while(0)
 #else
-#define mb()	__asm__ __volatile__ ("": : :"memory")
-#define rmb()	mb()
-#define wmb()	__asm__ __volatile__ ("": : :"memory")
+#define mb()		__asm__ __volatile__ ("": : :"memory")
+#define rmb()		mb()
+#define wmb()		__asm__ __volatile__ ("": : :"memory")
+#define ctrl_barrier()	__asm__ __volatile__ ("nop;nop;nop;nop;nop;nop;nop;nop")
 #define read_barrier_depends()	do { } while(0)
 #endif
 
@@ -218,8 +243,8 @@ do {					\
 #define back_to_P1()					\
 do {							\
 	unsigned long __dummy;				\
+	ctrl_barrier();					\
 	__asm__ __volatile__(				\
-		"nop;nop;nop;nop;nop;nop;nop\n\t"	\
 		"mov.l	1f, %0\n\t"			\
 		"jmp	@%0\n\t"			\
 		" nop\n\t"				\