1 /* 2 * Copyright (C) 2015 Linaro Ltd <ard.biesheuvel@linaro.org> 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 */ 8 9 #include <linux/efi.h> 10 #include <asm/efi.h> 11 #include <asm/mach/map.h> 12 #include <asm/mmu_context.h> 13 14 static int __init set_permissions(pte_t *ptep, pgtable_t token, 15 unsigned long addr, void *data) 16 { 17 efi_memory_desc_t *md = data; 18 pte_t pte = *ptep; 19 20 if (md->attribute & EFI_MEMORY_RO) 21 pte = set_pte_bit(pte, __pgprot(L_PTE_RDONLY)); 22 if (md->attribute & EFI_MEMORY_XP) 23 pte = set_pte_bit(pte, __pgprot(L_PTE_XN)); 24 set_pte_ext(ptep, pte, PTE_EXT_NG); 25 return 0; 26 } 27 28 int __init efi_set_mapping_permissions(struct mm_struct *mm, 29 efi_memory_desc_t *md) 30 { 31 unsigned long base, size; 32 33 base = md->virt_addr; 34 size = md->num_pages << EFI_PAGE_SHIFT; 35 36 /* 37 * We can only use apply_to_page_range() if we can guarantee that the 38 * entire region was mapped using pages. This should be the case if the 39 * region does not cover any naturally aligned SECTION_SIZE sized 40 * blocks. 41 */ 42 if (round_down(base + size, SECTION_SIZE) < 43 round_up(base, SECTION_SIZE) + SECTION_SIZE) 44 return apply_to_page_range(mm, base, size, set_permissions, md); 45 46 return 0; 47 } 48 49 int __init efi_create_mapping(struct mm_struct *mm, efi_memory_desc_t *md) 50 { 51 struct map_desc desc = { 52 .virtual = md->virt_addr, 53 .pfn = __phys_to_pfn(md->phys_addr), 54 .length = md->num_pages * EFI_PAGE_SIZE, 55 }; 56 57 /* 58 * Order is important here: memory regions may have all of the 59 * bits below set (and usually do), so we check them in order of 60 * preference. 61 */ 62 if (md->attribute & EFI_MEMORY_WB) 63 desc.type = MT_MEMORY_RWX; 64 else if (md->attribute & EFI_MEMORY_WT) 65 desc.type = MT_MEMORY_RWX_NONCACHED; 66 else if (md->attribute & EFI_MEMORY_WC) 67 desc.type = MT_DEVICE_WC; 68 else 69 desc.type = MT_DEVICE; 70 71 create_mapping_late(mm, &desc, true); 72 73 /* 74 * If stricter permissions were specified, apply them now. 75 */ 76 if (md->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP)) 77 return efi_set_mapping_permissions(mm, md); 78 return 0; 79 } 80