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Commit 74c102c9 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Catalin Marinas
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arm64: efi: avoid block mappings for unaligned UEFI memory regions 



When running the OS with a page size > 4 KB, we need to round up mappings
for regions that are not aligned to the OS's page size. We already avoid
block mappings for EfiRuntimeServicesCode/Data regions for other reasons,
but in the unlikely event that other unaliged regions exists that have the
EFI_MEMORY_RUNTIME attribute set, ensure that unaligned regions are always
mapped down to pages. This way, the overlapping page is guaranteed not to
be covered by a block mapping that needs to be split.

Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent bd264d04

arch/arm64/kernel/efi.c

+14 −0
Original line number Diff line number Diff line
@@ -65,6 +65,20 @@ int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md) 
	bool allow_block_mappings = (md->type != EFI_RUNTIME_SERVICES_CODE &&

				     md->type != EFI_RUNTIME_SERVICES_DATA);



	if (!PAGE_ALIGNED(md->phys_addr) ||

	    !PAGE_ALIGNED(md->num_pages << EFI_PAGE_SHIFT)) {

		/*

		 * If the end address of this region is not aligned to page

		 * size, the mapping is rounded up, and may end up sharing a

		 * page frame with the next UEFI memory region. If we create

		 * a block entry now, we may need to split it again when mapping

		 * the next region, and support for that is going to be removed

		 * from the MMU routines. So avoid block mappings altogether in

		 * that case.

		 */

		allow_block_mappings = false;

	}



	create_pgd_mapping(mm, md->phys_addr, md->virt_addr,

			   md->num_pages << EFI_PAGE_SHIFT,

			   __pgprot(prot_val | PTE_NG), allow_block_mappings);