1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2015 Linaro Ltd <ard.biesheuvel@linaro.org> 4 */ 5 6 #include <linux/efi.h> 7 #include <asm/efi.h> 8 #include <asm/mach/map.h> 9 #include <asm/mmu_context.h> 10 11 static int __init set_permissions(pte_t *ptep, unsigned long addr, void *data) 12 { 13 efi_memory_desc_t *md = data; 14 pte_t pte = *ptep; 15 16 if (md->attribute & EFI_MEMORY_RO) 17 pte = set_pte_bit(pte, __pgprot(L_PTE_RDONLY)); 18 if (md->attribute & EFI_MEMORY_XP) 19 pte = set_pte_bit(pte, __pgprot(L_PTE_XN)); 20 set_pte_ext(ptep, pte, PTE_EXT_NG); 21 return 0; 22 } 23 24 int __init efi_set_mapping_permissions(struct mm_struct *mm, 25 efi_memory_desc_t *md) 26 { 27 unsigned long base, size; 28 29 base = md->virt_addr; 30 size = md->num_pages << EFI_PAGE_SHIFT; 31 32 /* 33 * We can only use apply_to_page_range() if we can guarantee that the 34 * entire region was mapped using pages. This should be the case if the 35 * region does not cover any naturally aligned SECTION_SIZE sized 36 * blocks. 37 */ 38 if (round_down(base + size, SECTION_SIZE) < 39 round_up(base, SECTION_SIZE) + SECTION_SIZE) 40 return apply_to_page_range(mm, base, size, set_permissions, md); 41 42 return 0; 43 } 44 45 int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md) 46 { 47 struct map_desc desc = { 48 .virtual = md->virt_addr, 49 .pfn = __phys_to_pfn(md->phys_addr), 50 .length = md->num_pages * EFI_PAGE_SIZE, 51 }; 52 53 /* 54 * Order is important here: memory regions may have all of the 55 * bits below set (and usually do), so we check them in order of 56 * preference. 57 */ 58 if (md->attribute & EFI_MEMORY_WB) 59 desc.type = MT_MEMORY_RWX; 60 else if (md->attribute & EFI_MEMORY_WT) 61 desc.type = MT_MEMORY_RWX_NONCACHED; 62 else if (md->attribute & EFI_MEMORY_WC) 63 desc.type = MT_DEVICE_WC; 64 else 65 desc.type = MT_DEVICE; 66 67 create_mapping_late(mm, &desc, true); 68 69 /* 70 * If stricter permissions were specified, apply them now. 71 */ 72 if (md->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP)) 73 return efi_set_mapping_permissions(mm, md); 74 return 0; 75 } 76