[PATCH V7 4/5] arm64: apei: implement arch_apei_get_mem_attributes()

["Jonathan (Zhixiong) Zhang" <zjzhang@codeaurora.org>]

From: "Jonathan (Zhixiong) Zhang" <zjzhang@codeaurora.org>

If the physical address has memory attributes defined by EFI
memmap as EFI_MEMORY_UC, the page protection type is
PROT_DEVICE_nGnRE. Otherwise, the page protection type is
PAGE_KERNEL.

Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org>
---
This patch applies cleanly to efi-next-14364 of efi/next and
arm64-upstream-13521 of arm64/master, but needed slight change
to apply to next-20150720 of linux-next/master and
pm+acpi-4.2-rc3 of linux-pm/master. The later two branches
has newer arch/arm64/include/asm/acpi.h with following patch:
  b6cfb277378e ACPI / ARM64: add BAD_MADT_GICC_ENTRY() macro
---
 arch/arm64/include/asm/acpi.h | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index 1ff9e6eb5e02..41c7623d5b84 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -19,6 +19,11 @@
 #include <asm/psci.h>
 #include <asm/smp_plat.h>
 
+#ifdef CONFIG_ACPI_APEI
+#include <linux/efi.h>
+#include <asm/pgtable.h>
+#endif
+
 /* Basic configuration for ACPI */
 #ifdef	CONFIG_ACPI
 /* ACPI table mapping after acpi_gbl_permanent_mmap is set */
@@ -84,4 +89,25 @@ static inline const char *acpi_get_enable_method(int cpu)
 {
 	return acpi_psci_present() ? "psci" : NULL;
 }
+#ifdef	CONFIG_ACPI_APEI
+/*
+ * According to "Table 8 Map: EFI memory types to AArch64 memory types"
+ * of UEFI 2.5 section 2.3.6.1, each EFI memory type is mapped to
+ * corresponding MAIR attribute encoding.
+ */
+static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
+{
+	pgprot_t prot;
+
+	prot = efi_mem_attributes(addr);
+	if (prot & EFI_MEMORY_UC)
+		return PROT_DEVICE_nGnRnE;
+	if (prot & EFI_MEMORY_WC)
+		return PROT_NORMAL_NC;
+	if (prot & EFI_MEMORY_WT)
+		return PROT_NORMAL_WT;
+	return PAGE_KERNEL;
+}
+#endif
+
 #endif /*_ASM_ACPI_H*/
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project