Re: [PATCH 1/2] arm64: apei: implement arch_apei_get_mem_attributes()

[Zhang, Jonathan Zhixiong]

On 8/13/2015 1:22 AM, Ingo Molnar wrote:
> * Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> wrote:
>
> > 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>
> > Reviewed-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> > Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@xxxxxxxxxxxxxx>
> > Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>
> > ---
> >   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
Will do.
> > +	 * 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?
The function grew a bit after its first version. Since it is on the
fence of not being a small function, I did not change it to out of
the line. I will move it to arch/arm64/kernel/acpi.c guarded by
CONFIG_ACPI_APEI instead of having to create a very small new file,
if there is no opposition.
> Moving it to .c would also slightly improve compilation times for every .c file
> that includes asm/acpi.h.
>
> Thanks,
>
> 	Ingo

--
Jonathan (Zhixiong) Zhang
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
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