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