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, pgtable_t token, 12 unsigned long addr, void *data) 13 { 14 efi_memory_desc_t *md = data; 15 pte_t pte = *ptep; 16 17 if (md->attribute & EFI_MEMORY_RO) 18 pte = set_pte_bit(pte, __pgprot(L_PTE_RDONLY)); 19 if (md->attribute & EFI_MEMORY_XP) 20 pte = set_pte_bit(pte, __pgprot(L_PTE_XN)); 21 set_pte_ext(ptep, pte, PTE_EXT_NG); 22 return 0; 23 } 24 25 int __init efi_set_mapping_permissions(struct mm_struct *mm, 26 efi_memory_desc_t *md) 27 { 28 unsigned long base, size; 29 30 base = md->virt_addr; 31 size = md->num_pages << EFI_PAGE_SHIFT; 32 33 /* 34 * We can only use apply_to_page_range() if we can guarantee that the 35 * entire region was mapped using pages. This should be the case if the 36 * region does not cover any naturally aligned SECTION_SIZE sized 37 * blocks. 38 */ 39 if (round_down(base + size, SECTION_SIZE) < 40 round_up(base, SECTION_SIZE) + SECTION_SIZE) 41 return apply_to_page_range(mm, base, size, set_permissions, md); 42 43 return 0; 44 } 45 46 int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md) 47 { 48 struct map_desc desc = { 49 .virtual = md->virt_addr, 50 .pfn = __phys_to_pfn(md->phys_addr), 51 .length = md->num_pages * EFI_PAGE_SIZE, 52 }; 53 54 /* 55 * Order is important here: memory regions may have all of the 56 * bits below set (and usually do), so we check them in order of 57 * preference. 58 */ 59 if (md->attribute & EFI_MEMORY_WB) 60 desc.type = MT_MEMORY_RWX; 61 else if (md->attribute & EFI_MEMORY_WT) 62 desc.type = MT_MEMORY_RWX_NONCACHED; 63 else if (md->attribute & EFI_MEMORY_WC) 64 desc.type = MT_DEVICE_WC; 65 else 66 desc.type = MT_DEVICE; 67 68 create_mapping_late(mm, &desc, true); 69 70 /* 71 * If stricter permissions were specified, apply them now. 72 */ 73 if (md->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP)) 74 return efi_set_mapping_permissions(mm, md); 75 return 0; 76 } 77