From mboxrd@z Thu Jan 1 00:00:00 1970 From: Catalin Marinas Subject: [PATCH 2/3] arm64: efi: Ensure efi_create_mapping() does not map overlapping regions Date: Tue, 31 May 2016 16:14:31 +0100 Message-ID: <1464707672-21882-3-git-send-email-catalin.marinas@arm.com> References: <1464707672-21882-1-git-send-email-catalin.marinas@arm.com> Return-path: In-Reply-To: <1464707672-21882-1-git-send-email-catalin.marinas-5wv7dgnIgG8@public.gmane.org> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org Cc: Matt Fleming , Will Deacon , Mark Rutland , Jeremy Linton , linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-efi@vger.kernel.org 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 --- 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; }