linux-kernel - Re: [PATCH 1/2] arm64: apei: implement arch_apei_get_mem

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Date:	Thu, 13 Aug 2015 10:22:07 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Matt Fleming <matt@...eblueprint.co.uk>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Jonathan (Zhixiong) Zhang" <zjzhang@...eaurora.org>,
	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	Matt Fleming <matt.fleming@...el.com>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Hanjun Guo <hanjun.guo@...aro.org>
Subject: Re: [PATCH 1/2] arm64: apei: implement arch_apei_get_mem_attributes()


* Matt Fleming <matt@...eblueprint.co.uk> wrote:

> From: "Jonathan (Zhixiong) Zhang" <zjzhang@...eaurora.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@....com>
> Acked-by: Hanjun Guo <hanjun.guo@...aro.org>
> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@...eaurora.org>
> Signed-off-by: Matt Fleming <matt.fleming@...el.com>
> ---
>  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 406485ed110a..1cbad43e561d 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)
> @@ -92,4 +97,29 @@ 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.

s/mapped to corresponding/
  mapped to a corresponding

> +	 * 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

Also, this doesn't look like a small function - why is it inlined?

Moving it to .c would also slightly improve compilation times for every .c file 
that includes asm/acpi.h.

Thanks,

	Ingo
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