1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2016 Linaro Ltd. <ard.biesheuvel@linaro.org> 4 */ 5 6 #define pr_fmt(fmt) "efi: memattr: " fmt 7 8 #include <linux/efi.h> 9 #include <linux/init.h> 10 #include <linux/io.h> 11 #include <linux/memblock.h> 12 13 #include <asm/early_ioremap.h> 14 15 static int __initdata tbl_size; 16 17 /* 18 * Reserve the memory associated with the Memory Attributes configuration 19 * table, if it exists. 20 */ 21 int __init efi_memattr_init(void) 22 { 23 efi_memory_attributes_table_t *tbl; 24 25 if (efi.mem_attr_table == EFI_INVALID_TABLE_ADDR) 26 return 0; 27 28 tbl = early_memremap(efi.mem_attr_table, sizeof(*tbl)); 29 if (!tbl) { 30 pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n", 31 efi.mem_attr_table); 32 return -ENOMEM; 33 } 34 35 if (tbl->version > 1) { 36 pr_warn("Unexpected EFI Memory Attributes table version %d\n", 37 tbl->version); 38 goto unmap; 39 } 40 41 tbl_size = sizeof(*tbl) + tbl->num_entries * tbl->desc_size; 42 memblock_reserve(efi.mem_attr_table, tbl_size); 43 set_bit(EFI_MEM_ATTR, &efi.flags); 44 45 unmap: 46 early_memunmap(tbl, sizeof(*tbl)); 47 return 0; 48 } 49 50 /* 51 * Returns a copy @out of the UEFI memory descriptor @in if it is covered 52 * entirely by a UEFI memory map entry with matching attributes. The virtual 53 * address of @out is set according to the matching entry that was found. 54 */ 55 static bool entry_is_valid(const efi_memory_desc_t *in, efi_memory_desc_t *out) 56 { 57 u64 in_paddr = in->phys_addr; 58 u64 in_size = in->num_pages << EFI_PAGE_SHIFT; 59 efi_memory_desc_t *md; 60 61 *out = *in; 62 63 if (in->type != EFI_RUNTIME_SERVICES_CODE && 64 in->type != EFI_RUNTIME_SERVICES_DATA) { 65 pr_warn("Entry type should be RuntimeServiceCode/Data\n"); 66 return false; 67 } 68 69 if (!(in->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))) { 70 pr_warn("Entry attributes invalid: RO and XP bits both cleared\n"); 71 return false; 72 } 73 74 if (PAGE_SIZE > EFI_PAGE_SIZE && 75 (!PAGE_ALIGNED(in->phys_addr) || 76 !PAGE_ALIGNED(in->num_pages << EFI_PAGE_SHIFT))) { 77 /* 78 * Since arm64 may execute with page sizes of up to 64 KB, the 79 * UEFI spec mandates that RuntimeServices memory regions must 80 * be 64 KB aligned. We need to validate this here since we will 81 * not be able to tighten permissions on such regions without 82 * affecting adjacent regions. 83 */ 84 pr_warn("Entry address region misaligned\n"); 85 return false; 86 } 87 88 for_each_efi_memory_desc(md) { 89 u64 md_paddr = md->phys_addr; 90 u64 md_size = md->num_pages << EFI_PAGE_SHIFT; 91 92 if (!(md->attribute & EFI_MEMORY_RUNTIME)) 93 continue; 94 if (md->virt_addr == 0 && md->phys_addr != 0) { 95 /* no virtual mapping has been installed by the stub */ 96 break; 97 } 98 99 if (md_paddr > in_paddr || (in_paddr - md_paddr) >= md_size) 100 continue; 101 102 /* 103 * This entry covers the start of @in, check whether 104 * it covers the end as well. 105 */ 106 if (md_paddr + md_size < in_paddr + in_size) { 107 pr_warn("Entry covers multiple EFI memory map regions\n"); 108 return false; 109 } 110 111 if (md->type != in->type) { 112 pr_warn("Entry type deviates from EFI memory map region type\n"); 113 return false; 114 } 115 116 out->virt_addr = in_paddr + (md->virt_addr - md_paddr); 117 118 return true; 119 } 120 121 pr_warn("No matching entry found in the EFI memory map\n"); 122 return false; 123 } 124 125 /* 126 * To be called after the EFI page tables have been populated. If a memory 127 * attributes table is available, its contents will be used to update the 128 * mappings with tightened permissions as described by the table. 129 * This requires the UEFI memory map to have already been populated with 130 * virtual addresses. 131 */ 132 int __init efi_memattr_apply_permissions(struct mm_struct *mm, 133 efi_memattr_perm_setter fn) 134 { 135 efi_memory_attributes_table_t *tbl; 136 int i, ret; 137 138 if (tbl_size <= sizeof(*tbl)) 139 return 0; 140 141 /* 142 * We need the EFI memory map to be setup so we can use it to 143 * lookup the virtual addresses of all entries in the of EFI 144 * Memory Attributes table. If it isn't available, this 145 * function should not be called. 146 */ 147 if (WARN_ON(!efi_enabled(EFI_MEMMAP))) 148 return 0; 149 150 tbl = memremap(efi.mem_attr_table, tbl_size, MEMREMAP_WB); 151 if (!tbl) { 152 pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n", 153 efi.mem_attr_table); 154 return -ENOMEM; 155 } 156 157 if (efi_enabled(EFI_DBG)) 158 pr_info("Processing EFI Memory Attributes table:\n"); 159 160 for (i = ret = 0; ret == 0 && i < tbl->num_entries; i++) { 161 efi_memory_desc_t md; 162 unsigned long size; 163 bool valid; 164 char buf[64]; 165 166 valid = entry_is_valid((void *)tbl->entry + i * tbl->desc_size, 167 &md); 168 size = md.num_pages << EFI_PAGE_SHIFT; 169 if (efi_enabled(EFI_DBG) || !valid) 170 pr_info("%s 0x%012llx-0x%012llx %s\n", 171 valid ? "" : "!", md.phys_addr, 172 md.phys_addr + size - 1, 173 efi_md_typeattr_format(buf, sizeof(buf), &md)); 174 175 if (valid) { 176 ret = fn(mm, &md); 177 if (ret) 178 pr_err("Error updating mappings, skipping subsequent md's\n"); 179 } 180 } 181 memunmap(tbl); 182 return ret; 183 } 184