ARM: LPAE: add ISBs around MMU enabling code

Before we enable the MMU, we must ensure that the TTBR registers contain
sane values. After the MMU has been enabled, we jump to the *virtual*
address of the following function, so we also need to ensure that the
SCTLR write has taken effect.

This patch adds ISB instructions around the SCTLR write to ensure the
visibility of the above.
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

arch/arm/boot/compressed/head.S

@@ -659,6 +659,7 @@ __armv7_mmu_cache_on:
 		mcrne	p15, 0, r3, c2, c0, 0	@ load page table pointer
 		mcrne	p15, 0, r1, c3, c0, 0	@ load domain access control
 #endif
+		mcr	p15, 0, r0, c7, c5, 4	@ ISB
 		mcr	p15, 0, r0, c1, c0, 0	@ load control register
 		mrc	p15, 0, r0, c1, c0, 0	@ and read it back
 		mov	r0, #0

arch/arm/include/asm/assembler.h

@@ -186,6 +186,17 @@
 #define ALT_UP_B(label) b label
 #endif
 
+/*
+ * Instruction barrier
+ */
+	.macro	instr_sync
+#if __LINUX_ARM_ARCH__ >= 7
+	isb
+#elif __LINUX_ARM_ARCH__ == 6
+	mcr	p15, 0, r0, c7, c5, 4
+#endif
+	.endm
+
 /*
  * SMP data memory barrier
  */

arch/arm/kernel/head.S

@@ -401,8 +401,10 @@ ENDPROC(__enable_mmu)
 	.pushsection	.idmap.text, "ax"
 ENTRY(__turn_mmu_on)
 	mov	r0, r0
+	instr_sync
 	mcr	p15, 0, r0, c1, c0, 0		@ write control reg
 	mrc	p15, 0, r3, c0, c0, 0		@ read id reg
+	instr_sync
 	mov	r3, r3
 	mov	r3, r13
 	mov	pc, r3

arch/arm/kernel/sleep.S

@@ -57,8 +57,10 @@ ENDPROC(cpu_suspend_abort)
 	.pushsection	.idmap.text,"ax"
 ENTRY(cpu_resume_mmu)
 	ldr	r3, =cpu_resume_after_mmu
+	instr_sync
 	mcr	p15, 0, r0, c1, c0, 0	@ turn on MMU, I-cache, etc
 	mrc	p15, 0, r0, c0, c0, 0	@ read id reg
+	instr_sync
 	mov	r0, r0
 	mov	r0, r0
 	mov	pc, r3			@ jump to virtual address