[PATCH V4 3/4] 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>
---
 arch/arm64/kernel/Makefile |  1 +
 arch/arm64/kernel/apei.c   | 27 +++++++++++++++++++++++++++
 2 files changed, 28 insertions(+)
 create mode 100644 arch/arm64/kernel/apei.c

diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 426d0763c81b..c135f1e4e3b8 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -36,6 +36,7 @@ arm64-obj-$(CONFIG_EFI)			+= efi.o efi-stub.o efi-entry.o
 arm64-obj-$(CONFIG_PCI)			+= pci.o
 arm64-obj-$(CONFIG_ARMV8_DEPRECATED)	+= armv8_deprecated.o
 arm64-obj-$(CONFIG_ACPI)		+= acpi.o
+arm64-obj-$(CONFIG_ACPI_APEI)		+= apei.o
 
 obj-y					+= $(arm64-obj-y) vdso/
 obj-m					+= $(arm64-obj-m)
diff --git a/arch/arm64/kernel/apei.c b/arch/arm64/kernel/apei.c
new file mode 100644
index 000000000000..9c6b62f40ad7
--- /dev/null
+++ b/arch/arm64/kernel/apei.c
@@ -0,0 +1,27 @@
+/*
+ * Arch-specific APEI-related functions.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <acpi/apei.h>
+
+#include <linux/efi.h>
+
+#include <asm/pgtable.h>
+
+pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
+{
+	if (efi_mem_attributes(addr) & EFI_MEMORY_UC)
+		return PROT_DEVICE_nGnRE;
+	else
+		return PAGE_KERNEL;
+}
-- 
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