1 /* 2 * Copyright (C) 2016 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 #define pr_fmt(fmt) "efi: memattr: " fmt 10 11 #include <linux/efi.h> 12 #include <linux/init.h> 13 #include <linux/io.h> 14 #include <linux/memblock.h> 15 16 #include <asm/early_ioremap.h> 17 18 static int __initdata tbl_size; 19 20 /* 21 * Reserve the memory associated with the Memory Attributes configuration 22 * table, if it exists. 23 */ 24 int __init efi_memattr_init(void) 25 { 26 efi_memory_attributes_table_t *tbl; 27 28 if (efi.mem_attr_table == EFI_INVALID_TABLE_ADDR) 29 return 0; 30 31 tbl = early_memremap(efi.mem_attr_table, sizeof(*tbl)); 32 if (!tbl) { 33 pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n", 34 efi.mem_attr_table); 35 return -ENOMEM; 36 } 37 38 if (tbl->version > 1) { 39 pr_warn("Unexpected EFI Memory Attributes table version %d\n", 40 tbl->version); 41 goto unmap; 42 } 43 44 tbl_size = sizeof(*tbl) + tbl->num_entries * tbl->desc_size; 45 memblock_reserve(efi.mem_attr_table, tbl_size); 46 set_bit(EFI_MEM_ATTR, &efi.flags); 47 48 unmap: 49 early_memunmap(tbl, sizeof(*tbl)); 50 return 0; 51 } 52 53 /* 54 * Returns a copy @out of the UEFI memory descriptor @in if it is covered 55 * entirely by a UEFI memory map entry with matching attributes. The virtual 56 * address of @out is set according to the matching entry that was found. 57 */ 58 static bool entry_is_valid(const efi_memory_desc_t *in, efi_memory_desc_t *out) 59 { 60 u64 in_paddr = in->phys_addr; 61 u64 in_size = in->num_pages << EFI_PAGE_SHIFT; 62 efi_memory_desc_t *md; 63 64 *out = *in; 65 66 if (in->type != EFI_RUNTIME_SERVICES_CODE && 67 in->type != EFI_RUNTIME_SERVICES_DATA) { 68 pr_warn("Entry type should be RuntimeServiceCode/Data\n"); 69 return false; 70 } 71 72 if (!(in->attribute & (EFI_MEMORY_RO | EFI_MEMORY_XP))) { 73 pr_warn("Entry attributes invalid: RO and XP bits both cleared\n"); 74 return false; 75 } 76 77 if (PAGE_SIZE > EFI_PAGE_SIZE && 78 (!PAGE_ALIGNED(in->phys_addr) || 79 !PAGE_ALIGNED(in->num_pages << EFI_PAGE_SHIFT))) { 80 /* 81 * Since arm64 may execute with page sizes of up to 64 KB, the 82 * UEFI spec mandates that RuntimeServices memory regions must 83 * be 64 KB aligned. We need to validate this here since we will 84 * not be able to tighten permissions on such regions without 85 * affecting adjacent regions. 86 */ 87 pr_warn("Entry address region misaligned\n"); 88 return false; 89 } 90 91 for_each_efi_memory_desc(md) { 92 u64 md_paddr = md->phys_addr; 93 u64 md_size = md->num_pages << EFI_PAGE_SHIFT; 94 95 if (!(md->attribute & EFI_MEMORY_RUNTIME)) 96 continue; 97 if (md->virt_addr == 0) { 98 /* no virtual mapping has been installed by the stub */ 99 break; 100 } 101 102 if (md_paddr > in_paddr || (in_paddr - md_paddr) >= md_size) 103 continue; 104 105 /* 106 * This entry covers the start of @in, check whether 107 * it covers the end as well. 108 */ 109 if (md_paddr + md_size < in_paddr + in_size) { 110 pr_warn("Entry covers multiple EFI memory map regions\n"); 111 return false; 112 } 113 114 if (md->type != in->type) { 115 pr_warn("Entry type deviates from EFI memory map region type\n"); 116 return false; 117 } 118 119 out->virt_addr = in_paddr + (md->virt_addr - md_paddr); 120 121 return true; 122 } 123 124 pr_warn("No matching entry found in the EFI memory map\n"); 125 return false; 126 } 127 128 /* 129 * To be called after the EFI page tables have been populated. If a memory 130 * attributes table is available, its contents will be used to update the 131 * mappings with tightened permissions as described by the table. 132 * This requires the UEFI memory map to have already been populated with 133 * virtual addresses. 134 */ 135 int __init efi_memattr_apply_permissions(struct mm_struct *mm, 136 efi_memattr_perm_setter fn) 137 { 138 efi_memory_attributes_table_t *tbl; 139 int i, ret; 140 141 if (tbl_size <= sizeof(*tbl)) 142 return 0; 143 144 /* 145 * We need the EFI memory map to be setup so we can use it to 146 * lookup the virtual addresses of all entries in the of EFI 147 * Memory Attributes table. If it isn't available, this 148 * function should not be called. 149 */ 150 if (WARN_ON(!efi_enabled(EFI_MEMMAP))) 151 return 0; 152 153 tbl = memremap(efi.mem_attr_table, tbl_size, MEMREMAP_WB); 154 if (!tbl) { 155 pr_err("Failed to map EFI Memory Attributes table @ 0x%lx\n", 156 efi.mem_attr_table); 157 return -ENOMEM; 158 } 159 160 if (efi_enabled(EFI_DBG)) 161 pr_info("Processing EFI Memory Attributes table:\n"); 162 163 for (i = ret = 0; ret == 0 && i < tbl->num_entries; i++) { 164 efi_memory_desc_t md; 165 unsigned long size; 166 bool valid; 167 char buf[64]; 168 169 valid = entry_is_valid((void *)tbl->entry + i * tbl->desc_size, 170 &md); 171 size = md.num_pages << EFI_PAGE_SHIFT; 172 if (efi_enabled(EFI_DBG) || !valid) 173 pr_info("%s 0x%012llx-0x%012llx %s\n", 174 valid ? "" : "!", md.phys_addr, 175 md.phys_addr + size - 1, 176 efi_md_typeattr_format(buf, sizeof(buf), &md)); 177 178 if (valid) { 179 ret = fn(mm, &md); 180 if (ret) 181 pr_err("Error updating mappings, skipping subsequent md's\n"); 182 } 183 } 184 memunmap(tbl); 185 return ret; 186 } 187