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 > 2) { 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 (PAGE_SIZE > EFI_PAGE_SIZE && 71 (!PAGE_ALIGNED(in->phys_addr) || 72 !PAGE_ALIGNED(in->num_pages << EFI_PAGE_SHIFT))) { 73 /* 74 * Since arm64 may execute with page sizes of up to 64 KB, the 75 * UEFI spec mandates that RuntimeServices memory regions must 76 * be 64 KB aligned. We need to validate this here since we will 77 * not be able to tighten permissions on such regions without 78 * affecting adjacent regions. 79 */ 80 pr_warn("Entry address region misaligned\n"); 81 return false; 82 } 83 84 for_each_efi_memory_desc(md) { 85 u64 md_paddr = md->phys_addr; 86 u64 md_size = md->num_pages << EFI_PAGE_SHIFT; 87 88 if (!(md->attribute & EFI_MEMORY_RUNTIME)) 89 continue; 90 if (md->virt_addr == 0 && md->phys_addr != 0) { 91 /* no virtual mapping has been installed by the stub */ 92 break; 93 } 94 95 if (md_paddr > in_paddr || (in_paddr - md_paddr) >= md_size) 96 continue; 97 98 /* 99 * This entry covers the start of @in, check whether 100 * it covers the end as well. 101 */ 102 if (md_paddr + md_size < in_paddr + in_size) { 103 pr_warn("Entry covers multiple EFI memory map regions\n"); 104 return false; 105 } 106 107 if (md->type != in->type) { 108 pr_warn("Entry type deviates from EFI memory map region type\n"); 109 return false; 110 } 111 112 out->virt_addr = in_paddr + (md->virt_addr - md_paddr); 113 114 return true; 115 } 116 117 pr_warn("No matching entry found in the EFI memory map\n"); 118 return false; 119 } 120 121 /* 122 * To be called after the EFI page tables have been populated. If a memory 123 * attributes table is available, its contents will be used to update the 124 * mappings with tightened permissions as described by the table. 125 * This requires the UEFI memory map to have already been populated with 126 * virtual addresses. 127 */ 128 int __init efi_memattr_apply_permissions(struct mm_struct *mm, 129 efi_memattr_perm_setter fn) 130 { 131 efi_memory_attributes_table_t *tbl; 132 bool has_bti = false; 133 int i, ret; 134 135 if (tbl_size <= sizeof(*tbl)) 136 return 0; 137 138 /* 139 * We need the EFI memory map to be setup so we can use it to 140 * lookup the virtual addresses of all entries in the of EFI 141 * Memory Attributes table. If it isn't available, this 142 * function should not be called. 143 */ 144 if (WARN_ON(!efi_enabled(EFI_MEMMAP))) 145 return 0; 146 147 tbl = memremap(efi_mem_attr_table, tbl_size, MEMREMAP_WB); 148 if (!tbl) { 149 pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n", 150 efi_mem_attr_table); 151 return -ENOMEM; 152 } 153 154 if (tbl->version > 1 && 155 (tbl->flags & EFI_MEMORY_ATTRIBUTES_FLAGS_RT_FORWARD_CONTROL_FLOW_GUARD)) 156 has_bti = true; 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(efi_memdesc_ptr(tbl->entry, tbl->desc_size, i), 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, has_bti); 178 if (ret) 179 pr_err("Error updating mappings, skipping subsequent md's\n"); 180 } 181 } 182 memunmap(tbl); 183 return ret; 184 } 185