[PATCH V10 4/5] arm64: apei: implement arch_apei_get_mem_attributes()

[Jonathan (Zhixiong) Zhang]

From: "Jonathan (Zhixiong) Zhang" <zjzhang@xxxxxxxxxxxxxx>

Table 8 of UEFI 2.5 section 2.3.6.1 defines mappings from EFI
memory types to MAIR attribute encodings for arm64.

If the physical address has memory attributes defined by EFI
memmap as EFI_MEMORY_[UC|WC|WT], return approprate page protection
type according to the UEFI spec. Otherwise, return PAGE_KERNEL.

Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Acked-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@xxxxxxxxxxxxxx>
---
This patch as is does not build on current tip of next branch of
git.kernel.org/pub/scm/linux/kernel/git/mfleming/efi.git, a small
tweak is needed. It builds on tip of linux-next/master of linus'
repo and origin/master of arm64 repo.
---
 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..1025d0401016 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
+
 /* Macros for consistency checks of the GICC subtable of MADT */
 #define ACPI_MADT_GICC_LENGTH	\
 	(acpi_gbl_FADT.header.revision < 6 ? 76 : 80)
@@ -91,4 +95,26 @@ 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)
+{
+	u64 attr;
+
+	attr = efi_mem_attributes(addr);
+	if (attr & EFI_MEMORY_UC)
+		return __pgprot(PROT_DEVICE_nGnRnE);
+	if (attr & EFI_MEMORY_WC)
+		return __pgprot(PROT_NORMAL_NC);
+	if (attr & EFI_MEMORY_WT)
+		return __pgprot(PROT_NORMAL_WT);
+	return __pgprot(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

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