[PATCH 2/3] arm64: efi: Ensure efi_create_mapping() does not map overlapping regions
From: catalin.marinas@arm.com (Catalin Marinas)
Date: 2016-05-31 15:14:31
Also in:
linux-efi
Subsystem:
arm64 port (aarch64 architecture), extensible firmware interface (efi), the rest · Maintainers:
Catalin Marinas, Will Deacon, Ard Biesheuvel, Linus Torvalds
Since the EFI page size is 4KB, it is possible for a !4KB page kernel to align an EFI runtime map boundaries in a way that they can overlap within the same page. This requires the current create_pgd_mapping() code to be able to split existing larger mappings when an overlapping region needs to be mapped. With this patch, efi_create_mapping() scans the EFI memory map for overlapping regions and trims the length of the current map to avoid a large block mapping and subsequent split. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> --- arch/arm64/kernel/efi.c | 22 +++++++++++++++++++--- 1 file changed, 19 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 78f52488f9ff..0d5753c31c7f 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c@@ -62,10 +62,26 @@ struct screen_info screen_info __section(.data); int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md) { pteval_t prot_val = create_mapping_protection(md); + phys_addr_t length = md->num_pages << EFI_PAGE_SHIFT; + efi_memory_desc_t *next = md; - create_pgd_mapping(mm, md->phys_addr, md->virt_addr, - md->num_pages << EFI_PAGE_SHIFT, - __pgprot(prot_val | PTE_NG)); + /* + * Search for the next EFI runtime map and check for any overlap with + * the current map when aligned to PAGE_SIZE. In such case, defer + * mapping the end of the current range until the next + * efi_create_mapping() call. + */ + for_each_efi_memory_desc_continue(next) { + if (!(next->attribute & EFI_MEMORY_RUNTIME)) + continue; + if (next->phys_addr < PAGE_ALIGN(md->phys_addr + length)) + length -= (md->phys_addr + length) & ~PAGE_MASK; + break; + } + + if (length) + create_pgd_mapping(mm, md->phys_addr, md->virt_addr, length, + __pgprot(prot_val | PTE_NG)); return 0; }