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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: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ard Biesheuvel 2016-06-29 14:51:28 +02:00 committed by Catalin Marinas
parent bd264d046a
commit 74c102c988
1 changed files with 14 additions and 0 deletions
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14
arch/arm64/kernel/efi.c
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@ -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);