> On 27 aug. 2015, at 11:32, Will Deacon <will.deacon@xxxxxxx> wrote:
>
> Hi Ard,
>
>> On Wed, Aug 26, 2015 at 02:30:02PM +0100, Ard Biesheuvel wrote:
>> Currently, we infer the UEFI memory region mapping permissions
>> from the memory region type (i.e., runtime services code are
>> mapped RWX and runtime services data mapped RW-). This appears to
>> work fine but is not entirely UEFI spec compliant. So instead, use
>> the designated permission attributes to decide how these regions
>> should be mapped.
>>
>> Since UEFIv2.5 introduces a new EFI_MEMORY_RO permission attribute,
>> and redefines EFI_MEMORY_WP as a cacheability attribute, use only
>> the former as a read-only attribute. For setting the PXN bit, the
>> corresponding EFI_MEMORY_XP attribute is used.
>>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
>> ---
>> Changes since v1:
>> - rewrote page size and alignment check to be more legible
>> - use code that is STRICT_MM_TYPECHECKS compliant
>>
>> Example output of a recent Tianocore build on FVP Foundation model
>> is attached below.
>>
>> arch/arm64/kernel/efi.c | 37 +++++++++++++-------
>> 1 file changed, 24 insertions(+), 13 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
>> index ab21e0d58278..c8d587f46f3e 100644
>> --- a/arch/arm64/kernel/efi.c
>> +++ b/arch/arm64/kernel/efi.c
>> @@ -235,7 +235,7 @@ static bool __init efi_virtmap_init(void)
>>
>> for_each_efi_memory_desc(&memmap, md) {
>> u64 paddr, npages, size;
>> - pgprot_t prot;
>> + pteval_t prot_val;
>>
>> if (!(md->attribute & EFI_MEMORY_RUNTIME))
>> continue;
>> @@ -247,22 +247,33 @@ static bool __init efi_virtmap_init(void)
>> memrange_efi_to_native(&paddr, &npages);
>> size = npages << PAGE_SHIFT;
>>
>> - pr_info(" EFI remap 0x%016llx => %p\n",
>> - md->phys_addr, (void *)md->virt_addr);
>> + if (!is_normal_ram(md))
>> + prot_val = PROT_DEVICE_nGnRE;
>> + else
>> + prot_val = pgprot_val(PAGE_KERNEL_EXEC);
>>
>> /*
>> - * Only regions of type EFI_RUNTIME_SERVICES_CODE need to be
>> - * executable, everything else can be mapped with the XN bits
>> - * set.
>> + * On 64 KB granule kernels, only use strict permissions when
>> + * the region does not share a 64 KB page frame with another
>> + * region at either end.
>> */
>> - if (!is_normal_ram(md))
>> - prot = __pgprot(PROT_DEVICE_nGnRE);
>> - else if (md->type == EFI_RUNTIME_SERVICES_CODE)
>> - prot = PAGE_KERNEL_EXEC;
>> - else
>> - prot = PAGE_KERNEL;
>> + if (PAGE_SIZE == EFI_PAGE_SIZE ||
>> + (PAGE_ALIGNED(md->virt_addr) &&
>> + PAGE_ALIGNED(md->phys_addr + md->num_pages * EFI_PAGE_SIZE))) {
>
> Why do you use virt_addr instead of phys_addr for the base check?
No reason in particular, as far as I remember, so i should probably change that
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