From bd264d046aad25e9922a142a7831e6841a2f0474 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Wed, 29 Jun 2016 14:51:27 +0200 Subject: [PATCH] arm64: efi: always map runtime services code and data regions down to pages To avoid triggering diagnostics in the MMU code that are finicky about splitting block mappings into more granular mappings, ensure that regions that are likely to appear in the Memory Attributes table as well as the UEFI memory map are always mapped down to pages. This way, we can use apply_to_page_range() instead of create_pgd_mapping() for the second pass, which cannot split or merge block entries, and operates strictly on PTEs. Note that this aligns the arm64 Memory Attributes table handling code with the ARM code, which already uses apply_to_page_range() to set the strict permissions. Signed-off-by: Ard Biesheuvel Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/efi.h | 3 +-- arch/arm64/kernel/efi.c | 36 +++++++++++++++++++++++++++++++++++- 2 files changed, 36 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h index 622db3c6474e..8b13476cdf96 100644 --- a/arch/arm64/include/asm/efi.h +++ b/arch/arm64/include/asm/efi.h @@ -14,8 +14,7 @@ extern void efi_init(void); #endif int efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md); - -#define efi_set_mapping_permissions efi_create_mapping +int efi_set_mapping_permissions(struct mm_struct *mm, efi_memory_desc_t *md); #define arch_efi_call_virt_setup() \ ({ \ diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c index 981604948521..4aef89f37049 100644 --- a/arch/arm64/kernel/efi.c +++ b/arch/arm64/kernel/efi.c @@ -62,13 +62,47 @@ 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); + bool allow_block_mappings = (md->type != EFI_RUNTIME_SERVICES_CODE && + md->type != EFI_RUNTIME_SERVICES_DATA); create_pgd_mapping(mm, md->phys_addr, md->virt_addr, md->num_pages << EFI_PAGE_SHIFT, - __pgprot(prot_val | PTE_NG), true); + __pgprot(prot_val | PTE_NG), allow_block_mappings); return 0; } +static int __init set_permissions(pte_t *ptep, pgtable_t token, + unsigned long addr, void *data) +{ + efi_memory_desc_t *md = data; + pte_t pte = *ptep; + + if (md->attribute & EFI_MEMORY_RO) + pte = set_pte_bit(pte, __pgprot(PTE_RDONLY)); + if (md->attribute & EFI_MEMORY_XP) + pte = set_pte_bit(pte, __pgprot(PTE_PXN)); + set_pte(ptep, pte); + return 0; +} + +int __init efi_set_mapping_permissions(struct mm_struct *mm, + efi_memory_desc_t *md) +{ + BUG_ON(md->type != EFI_RUNTIME_SERVICES_CODE && + md->type != EFI_RUNTIME_SERVICES_DATA); + + /* + * Calling apply_to_page_range() is only safe on regions that are + * guaranteed to be mapped down to pages. Since we are only called + * for regions that have been mapped using efi_create_mapping() above + * (and this is checked by the generic Memory Attributes table parsing + * routines), there is no need to check that again here. + */ + return apply_to_page_range(mm, md->virt_addr, + md->num_pages << EFI_PAGE_SHIFT, + set_permissions, md); +} + static int __init arm64_dmi_init(void) { /* -- 2.30.2