On 11 August 2015 at 23:57, Matt Fleming matt@codeblueprint.co.uk wrote:
On Sat, 08 Aug, at 10:18:52AM, Jonathan (Zhixiong) Zhang wrote:
From: "Jonathan (Zhixiong) Zhang" zjzhang@codeaurora.org
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@arm.com Acked-by: Hanjun Guo hanjun.guo@linaro.org Signed-off-by: Jonathan (Zhixiong) Zhang zjzhang@codeaurora.org
arch/arm64/include/asm/acpi.h | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+)
diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h index 614096732839..b77a2d133da9 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 +95,29 @@ static inline const char *acpi_get_enable_method(int cpu) { return acpi_psci_present() ? "psci" : NULL; }
+#ifdef CONFIG_ACPI_APEI +static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr) +{
/** 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.* The EFI memory attribute advises all possible capabilities of a* memory region. We use the most efficient capability.*/u64 attr;attr = efi_mem_attributes(addr);if (attr & EFI_MEMORY_WB)return PAGE_KERNEL;if (attr & EFI_MEMORY_WT)return __pgprot(PROT_NORMAL_WT);if (attr & EFI_MEMORY_WC)return __pgprot(PROT_NORMAL_NC);return __pgprot(PROT_DEVICE_nGnRnE);+} +#endif
#endif /*_ASM_ACPI_H*/
Everyone happy with this change? Ard?
Yes, this looks fine. As long as any region that has the EFI_MEMORY_WB attribute gets mapped as PAGE_KERNEL, we know we won't be violating any architectural mismatched attributes constraints (since all EFI_MEMORY_WB regions, even the occupied ones, are covered by the kernel direct mapping as well)
For the other ones, it is merely an optimization, but arguably still an improvement.
Reviewed-by: Ard Biesheuvel ard.biesheuvel@linaro.org
Thanks, Ard.