ARM: 6743/1: errata: interrupted ICALLUIS may prevent completion of broadcasted operation

On versions of the Cortex-A9 prior to r3p0, an interrupted ICIALLUIS
operation may prevent the completion of a following broadcasted
operation if the second operation is received by a CPU before the
ICIALLUIS has completed, potentially leading to corrupted entries in
the cache or TLB.

This workaround sets a bit in the diagnostic register of the Cortex-A9,
causing CP15 maintenance operations to be uninterruptible.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Kconfig

@@ -1177,6 +1177,16 @@ config ARM_ERRATA_743622
 	  visible impact on the overall performance or power consumption of the
 	  processor.
 
+config ARM_ERRATA_751472
+	bool "ARM errata: Interrupted ICIALLUIS may prevent completion of broadcasted operation"
+	depends on CPU_V7 && SMP
+	help
+	  This option enables the workaround for the 751472 Cortex-A9 (prior
+	  to r3p0) erratum. An interrupted ICIALLUIS operation may prevent the
+	  completion of a following broadcasted operation if the second
+	  operation is received by a CPU before the ICIALLUIS has completed,
+	  potentially leading to corrupted entries in the cache or TLB.
+
 config ARM_ERRATA_753970
 	bool "ARM errata: cache sync operation may be faulty"
 	depends on CACHE_PL310

arch/arm/mm/proc-v7.S

@@ -264,6 +264,12 @@ __v7_setup:
 	orreq	r10, r10, #1 << 6		@ set bit #6
 	mcreq	p15, 0, r10, c15, c0, 1		@ write diagnostic register
 #endif
+#ifdef CONFIG_ARM_ERRATA_751472
+	cmp	r6, #0x30			@ present prior to r3p0
+	mrclt	p15, 0, r10, c15, c0, 1		@ read diagnostic register
+	orrlt	r10, r10, #1 << 11		@ set bit #11
+	mcrlt	p15, 0, r10, c15, c0, 1		@ write diagnostic register
+#endif
 
 3:	mov	r10, #0
 #ifdef HARVARD_CACHE