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 unsigned long __ro_after_init efi_mem_attr_table = EFI_INVALID_TABLE_ADDR; 17 18 /* 19 * Reserve the memory associated with the Memory Attributes configuration 20 * table, if it exists. 21 */ 22 int __init efi_memattr_init(void) 23 { 24 efi_memory_attributes_table_t *tbl; 25 26 if (efi_mem_attr_table == EFI_INVALID_TABLE_ADDR) 27 return 0; 28 29 tbl = early_memremap(efi_mem_attr_table, sizeof(*tbl)); 30 if (!tbl) { 31 pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n", 32 efi_mem_attr_table); 33 return -ENOMEM; 34 } 35 36 if (tbl->version > 1) { 37 pr_warn("Unexpected EFI Memory Attributes table version %d\n", 38 tbl->version); 39 goto unmap; 40 } 41 42 tbl_size = sizeof(*tbl) + tbl->num_entries * tbl->desc_size; 43 memblock_reserve(efi_mem_attr_table, tbl_size); 44 set_bit(EFI_MEM_ATTR, &efi.flags); 45 46 unmap: 47 early_memunmap(tbl, sizeof(*tbl)); 48 return 0; 49 } 50 51 /* 52 * Returns a copy @out of the UEFI memory descriptor @in if it is covered 53 * entirely by a UEFI memory map entry with matching attributes. The virtual 54 * address of @out is set according to the matching entry that was found. 55 */ 56 static bool entry_is_valid(const efi_memory_desc_t *in, efi_memory_desc_t *out) 57 { 58 u64 in_paddr = in->phys_addr; 59 u64 in_size = in->num_pages << EFI_PAGE_SHIFT; 60 efi_memory_desc_t *md; 61 62 *out = *in; 63 64 if (in->type != EFI_RUNTIME_SERVICES_CODE && 65 in->type != EFI_RUNTIME_SERVICES_DATA) { 66 pr_warn("Entry type should be RuntimeServiceCode/Data\n"); 67 return false; 68 } 69 70 if (!(in->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))) { 71 pr_warn("Entry attributes invalid: RO and XP bits both cleared\n"); 72 return false; 73 } 74 75 if (PAGE_SIZE > EFI_PAGE_SIZE && 76 (!PAGE_ALIGNED(in->phys_addr) || 77 !PAGE_ALIGNED(in->num_pages << EFI_PAGE_SHIFT))) { 78 /* 79 * Since arm64 may execute with page sizes of up to 64 KB, the 80 * UEFI spec mandates that RuntimeServices memory regions must 81 * be 64 KB aligned. We need to validate this here since we will 82 * not be able to tighten permissions on such regions without 83 * affecting adjacent regions. 84 */ 85 pr_warn("Entry address region misaligned\n"); 86 return false; 87 } 88 89 for_each_efi_memory_desc(md) { 90 u64 md_paddr = md->phys_addr; 91 u64 md_size = md->num_pages << EFI_PAGE_SHIFT; 92 93 if (!(md->attribute & EFI_MEMORY_RUNTIME)) 94 continue; 95 if (md->virt_addr == 0 && md->phys_addr != 0) { 96 /* no virtual mapping has been installed by the stub */ 97 break; 98 } 99 100 if (md_paddr > in_paddr || (in_paddr - md_paddr) >= md_size) 101 continue; 102 103 /* 104 * This entry covers the start of @in, check whether 105 * it covers the end as well. 106 */ 107 if (md_paddr + md_size < in_paddr + in_size) { 108 pr_warn("Entry covers multiple EFI memory map regions\n"); 109 return false; 110 } 111 112 if (md->type != in->type) { 113 pr_warn("Entry type deviates from EFI memory map region type\n"); 114 return false; 115 } 116 117 out->virt_addr = in_paddr + (md->virt_addr - md_paddr); 118 119 return true; 120 } 121 122 pr_warn("No matching entry found in the EFI memory map\n"); 123 return false; 124 } 125 126 /* 127 * To be called after the EFI page tables have been populated. If a memory 128 * attributes table is available, its contents will be used to update the 129 * mappings with tightened permissions as described by the table. 130 * This requires the UEFI memory map to have already been populated with 131 * virtual addresses. 132 */ 133 int __init efi_memattr_apply_permissions(struct mm_struct *mm, 134 efi_memattr_perm_setter fn) 135 { 136 efi_memory_attributes_table_t *tbl; 137 int i, ret; 138 139 if (tbl_size <= sizeof(*tbl)) 140 return 0; 141 142 /* 143 * We need the EFI memory map to be setup so we can use it to 144 * lookup the virtual addresses of all entries in the of EFI 145 * Memory Attributes table. If it isn't available, this 146 * function should not be called. 147 */ 148 if (WARN_ON(!efi_enabled(EFI_MEMMAP))) 149 return 0; 150 151 tbl = memremap(efi_mem_attr_table, tbl_size, MEMREMAP_WB); 152 if (!tbl) { 153 pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n", 154 efi_mem_attr_table); 155 return -ENOMEM; 156 } 157 158 if (efi_enabled(EFI_DBG)) 159 pr_info("Processing EFI Memory Attributes table:\n"); 160 161 for (i = ret = 0; ret == 0 && i < tbl->num_entries; i++) { 162 efi_memory_desc_t md; 163 unsigned long size; 164 bool valid; 165 char buf[64]; 166 167 valid = entry_is_valid((void *)tbl->entry + i * tbl->desc_size, 168 &md); 169 size = md.num_pages << EFI_PAGE_SHIFT; 170 if (efi_enabled(EFI_DBG) || !valid) 171 pr_info("%s 0x%012llx-0x%012llx %s\n", 172 valid ? "" : "!", md.phys_addr, 173 md.phys_addr + size - 1, 174 efi_md_typeattr_format(buf, sizeof(buf), &md)); 175 176 if (valid) { 177 ret = fn(mm, &md); 178 if (ret) 179 pr_err("Error updating mappings, skipping subsequent md's\n"); 180 } 181 } 182 memunmap(tbl); 183 return ret; 184 } 185