arm64: efi: avoid block mappings for unaligned UEFI memory regions (74c102c9) · Commits · 戴 / test

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:

Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by:

Catalin Marinas <catalin.marinas@arm.com>

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);

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