[PATCH 3/5] arm64: efi: avoid block mappings for unaligned UEFI memory regions
From: Ard Biesheuvel <hidden>
Date: 2016-06-29 12:51:28
Also in:
linux-efi
Subsystem:
arm64 port (aarch64 architecture), extensible firmware interface (efi), the rest · Maintainers:
Catalin Marinas, Will Deacon, Ard Biesheuvel, Linus Torvalds
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 <redacted> --- arch/arm64/kernel/efi.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 4aef89f37049..ba9bee389fd5 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c@@ -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);
--
2.7.4