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?
Will
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