arm64/mm: Add PROT_DEVICE_nGnRnE and PROT_NORMAL_WT

UEFI spec 2.5 section 2.3.6.1 defines that
EFI_MEMORY_[UC|WC|WT|WB] are possible EFI memory types for
AArch64.

Each of those EFI memory types is mapped to a corresponding
AArch64 memory type. So we need to define PROT_DEVICE_nGnRnE
and PROT_NORMWL_WT additionaly.

MT_NORMAL_WT is defined, and its encoding is added to MAIR_EL1
when initializing the CPU.

Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1438936621-5215-6-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/arm64/include/asm/memory.h

@@ -100,6 +100,7 @@
 #define MT_DEVICE_GRE		2
 #define MT_NORMAL_NC		3
 #define MT_NORMAL		4
+#define MT_NORMAL_WT		5
 
 /*
  * Memory types for Stage-2 translation

arch/arm64/include/asm/pgtable.h

@@ -61,8 +61,10 @@ extern void __pgd_error(const char *file, int line, unsigned long val);
 #define PROT_SECT_DEFAULT	(PMD_TYPE_SECT | PMD_SECT_AF)
 #endif
 
+#define PROT_DEVICE_nGnRnE	(PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_DEVICE_nGnRnE))
 #define PROT_DEVICE_nGnRE	(PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_DEVICE_nGnRE))
 #define PROT_NORMAL_NC		(PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_NORMAL_NC))
+#define PROT_NORMAL_WT		(PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_NORMAL_WT))
 #define PROT_NORMAL		(PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_NORMAL))
 
 #define PROT_SECT_DEVICE_nGnRE	(PROT_SECT_DEFAULT | PMD_SECT_PXN | PMD_SECT_UXN | PMD_ATTRINDX(MT_DEVICE_nGnRE))

arch/arm64/mm/proc.S

@@ -167,12 +167,14 @@ ENTRY(__cpu_setup)
 	 *   DEVICE_GRE		010	00001100
 	 *   NORMAL_NC		011	01000100
 	 *   NORMAL		100	11111111
+	 *   NORMAL_WT		101	10111011
 	 */
 	ldr	x5, =MAIR(0x00, MT_DEVICE_nGnRnE) | \
 		     MAIR(0x04, MT_DEVICE_nGnRE) | \
 		     MAIR(0x0c, MT_DEVICE_GRE) | \
 		     MAIR(0x44, MT_NORMAL_NC) | \
-		     MAIR(0xff, MT_NORMAL)
+		     MAIR(0xff, MT_NORMAL) | \
+		     MAIR(0xbb, MT_NORMAL_WT)
 	msr	mair_el1, x5
 	/*
 	 * Prepare SCTLR