drivers/firmware/efi/efi.c

   1 /*
   2  * efi.c - EFI subsystem
   3  *
   4  * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
   5  * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
   6  * Copyright (C) 2013 Tom Gundersen <teg@jklm.no>
   7  *
   8  * This code registers /sys/firmware/efi{,/efivars} when EFI is supported,
   9  * allowing the efivarfs to be mounted or the efivars module to be loaded.
  10  * The existance of /sys/firmware/efi may also be used by userspace to
  11  * determine that the system supports EFI.
  12  *
  13  * This file is released under the GPLv2.
  14  */
  15
  16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  17
  18 #include <linux/kobject.h>
  19 #include <linux/module.h>
  20 #include <linux/init.h>
  21 #include <linux/device.h>
  22 #include <linux/efi.h>
  23 #include <linux/io.h>
  24
  25 struct efi __read_mostly efi = {
  26         .mps        = EFI_INVALID_TABLE_ADDR,
  27         .acpi       = EFI_INVALID_TABLE_ADDR,
  28         .acpi20     = EFI_INVALID_TABLE_ADDR,
  29         .smbios     = EFI_INVALID_TABLE_ADDR,
  30         .sal_systab = EFI_INVALID_TABLE_ADDR,
  31         .boot_info  = EFI_INVALID_TABLE_ADDR,
  32         .hcdp       = EFI_INVALID_TABLE_ADDR,
  33         .uga        = EFI_INVALID_TABLE_ADDR,
  34         .uv_systab  = EFI_INVALID_TABLE_ADDR,
  35 };
  36 EXPORT_SYMBOL(efi);
  37
  38 static struct kobject *efi_kobj;
  39 static struct kobject *efivars_kobj;
  40
  41 /*
  42  * Let's not leave out systab information that snuck into
  43  * the efivars driver
  44  */
  45 static ssize_t systab_show(struct kobject *kobj,
  46                            struct kobj_attribute *attr, char *buf)
  47 {
  48         char *str = buf;
  49
  50         if (!kobj || !buf)
  51                 return -EINVAL;
  52
  53         if (efi.mps != EFI_INVALID_TABLE_ADDR)
  54                 str += sprintf(str, "MPS=0x%lx\n", efi.mps);
  55         if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
  56                 str += sprintf(str, "ACPI20=0x%lx\n", efi.acpi20);
  57         if (efi.acpi != EFI_INVALID_TABLE_ADDR)
  58                 str += sprintf(str, "ACPI=0x%lx\n", efi.acpi);
  59         if (efi.smbios != EFI_INVALID_TABLE_ADDR)
  60                 str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios);
  61         if (efi.hcdp != EFI_INVALID_TABLE_ADDR)
  62                 str += sprintf(str, "HCDP=0x%lx\n", efi.hcdp);
  63         if (efi.boot_info != EFI_INVALID_TABLE_ADDR)
  64                 str += sprintf(str, "BOOTINFO=0x%lx\n", efi.boot_info);
  65         if (efi.uga != EFI_INVALID_TABLE_ADDR)
  66                 str += sprintf(str, "UGA=0x%lx\n", efi.uga);
  67
  68         return str - buf;
  69 }
  70
  71 static struct kobj_attribute efi_attr_systab =
  72                         __ATTR(systab, 0400, systab_show, NULL);
  73
  74 static struct attribute *efi_subsys_attrs[] = {
  75         &efi_attr_systab.attr,
  76         NULL,   /* maybe more in the future? */
  77 };
  78
  79 static struct attribute_group efi_subsys_attr_group = {
  80         .attrs = efi_subsys_attrs,
  81 };
  82
  83 static struct efivars generic_efivars;
  84 static struct efivar_operations generic_ops;
  85
  86 static int generic_ops_register(void)
  87 {
  88         generic_ops.get_variable = efi.get_variable;
  89         generic_ops.set_variable = efi.set_variable;
  90         generic_ops.get_next_variable = efi.get_next_variable;
  91         generic_ops.query_variable_store = efi_query_variable_store;
  92
  93         return efivars_register(&generic_efivars, &generic_ops, efi_kobj);
  94 }
  95
  96 static void generic_ops_unregister(void)
  97 {
  98         efivars_unregister(&generic_efivars);
  99 }
 100
 101 /*
 102  * We register the efi subsystem with the firmware subsystem and the
 103  * efivars subsystem with the efi subsystem, if the system was booted with
 104  * EFI.
 105  */
 106 static int __init efisubsys_init(void)
 107 {
 108         int error;
 109
 110         if (!efi_enabled(EFI_BOOT))
 111                 return 0;
 112
 113         /* We register the efi directory at /sys/firmware/efi */
 114         efi_kobj = kobject_create_and_add("efi", firmware_kobj);
 115         if (!efi_kobj) {
 116                 pr_err("efi: Firmware registration failed.\n");
 117                 return -ENOMEM;
 118         }
 119
 120         error = generic_ops_register();
 121         if (error)
 122                 goto err_put;
 123
 124         error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group);
 125         if (error) {
 126                 pr_err("efi: Sysfs attribute export failed with error %d.\n",
 127                        error);
 128                 goto err_unregister;
 129         }
 130
 131         /* and the standard mountpoint for efivarfs */
 132         efivars_kobj = kobject_create_and_add("efivars", efi_kobj);
 133         if (!efivars_kobj) {
 134                 pr_err("efivars: Subsystem registration failed.\n");
 135                 error = -ENOMEM;
 136                 goto err_remove_group;
 137         }
 138
 139         return 0;
 140
 141 err_remove_group:
 142         sysfs_remove_group(efi_kobj, &efi_subsys_attr_group);
 143 err_unregister:
 144         generic_ops_unregister();
 145 err_put:
 146         kobject_put(efi_kobj);
 147         return error;
 148 }
 149
 150 subsys_initcall(efisubsys_init);
 151
 152
 153 /*
 154  * We can't ioremap data in EFI boot services RAM, because we've already mapped
 155  * it as RAM.  So, look it up in the existing EFI memory map instead.  Only
 156  * callable after efi_enter_virtual_mode and before efi_free_boot_services.
 157  */
 158 void __iomem *efi_lookup_mapped_addr(u64 phys_addr)
 159 {
 160         struct efi_memory_map *map;
 161         void *p;
 162         map = efi.memmap;
 163         if (!map)
 164                 return NULL;
 165         if (WARN_ON(!map->map))
 166                 return NULL;
 167         for (p = map->map; p < map->map_end; p += map->desc_size) {
 168                 efi_memory_desc_t *md = p;
 169                 u64 size = md->num_pages << EFI_PAGE_SHIFT;
 170                 u64 end = md->phys_addr + size;
 171                 if (!(md->attribute & EFI_MEMORY_RUNTIME) &&
 172                     md->type != EFI_BOOT_SERVICES_CODE &&
 173                     md->type != EFI_BOOT_SERVICES_DATA)
 174                         continue;
 175                 if (!md->virt_addr)
 176                         continue;
 177                 if (phys_addr >= md->phys_addr && phys_addr < end) {
 178                         phys_addr += md->virt_addr - md->phys_addr;
 179                         return (__force void __iomem *)(unsigned long)phys_addr;
 180                 }
 181         }
 182         return NULL;
 183 }
 184
 185 static __initdata efi_config_table_type_t common_tables[] = {
 186         {ACPI_20_TABLE_GUID, "ACPI 2.0", &efi.acpi20},
 187         {ACPI_TABLE_GUID, "ACPI", &efi.acpi},
 188         {HCDP_TABLE_GUID, "HCDP", &efi.hcdp},
 189         {MPS_TABLE_GUID, "MPS", &efi.mps},
 190         {SAL_SYSTEM_TABLE_GUID, "SALsystab", &efi.sal_systab},
 191         {SMBIOS_TABLE_GUID, "SMBIOS", &efi.smbios},
 192         {UGA_IO_PROTOCOL_GUID, "UGA", &efi.uga},
 193         {NULL_GUID, NULL, 0},
 194 };
 195
 196 static __init int match_config_table(efi_guid_t *guid,
 197                                      unsigned long table,
 198                                      efi_config_table_type_t *table_types)
 199 {
 200         u8 str[EFI_VARIABLE_GUID_LEN + 1];
 201         int i;
 202
 203         if (table_types) {
 204                 efi_guid_unparse(guid, str);
 205
 206                 for (i = 0; efi_guidcmp(table_types[i].guid, NULL_GUID); i++) {
 207                         efi_guid_unparse(&table_types[i].guid, str);
 208
 209                         if (!efi_guidcmp(*guid, table_types[i].guid)) {
 210                                 *(table_types[i].ptr) = table;
 211                                 pr_cont(" %s=0x%lx ",
 212                                         table_types[i].name, table);
 213                                 return 1;
 214                         }
 215                 }
 216         }
 217
 218         return 0;
 219 }
 220
 221 int __init efi_config_init(efi_config_table_type_t *arch_tables)
 222 {
 223         void *config_tables, *tablep;
 224         int i, sz;
 225
 226         if (efi_enabled(EFI_64BIT))
 227                 sz = sizeof(efi_config_table_64_t);
 228         else
 229                 sz = sizeof(efi_config_table_32_t);
 230
 231         /*
 232          * Let's see what config tables the firmware passed to us.
 233          */
 234         config_tables = early_memremap(efi.systab->tables,
 235                                        efi.systab->nr_tables * sz);
 236         if (config_tables == NULL) {
 237                 pr_err("Could not map Configuration table!\n");
 238                 return -ENOMEM;
 239         }
 240
 241         tablep = config_tables;
 242         pr_info("");
 243         for (i = 0; i < efi.systab->nr_tables; i++) {
 244                 efi_guid_t guid;
 245                 unsigned long table;
 246
 247                 if (efi_enabled(EFI_64BIT)) {
 248                         u64 table64;
 249                         guid = ((efi_config_table_64_t *)tablep)->guid;
 250                         table64 = ((efi_config_table_64_t *)tablep)->table;
 251                         table = table64;
 252 #ifndef CONFIG_64BIT
 253                         if (table64 >> 32) {
 254                                 pr_cont("\n");
 255                                 pr_err("Table located above 4GB, disabling EFI.\n");
 256                                 early_iounmap(config_tables,
 257                                                efi.systab->nr_tables * sz);
 258                                 return -EINVAL;
 259                         }
 260 #endif
 261                 } else {
 262                         guid = ((efi_config_table_32_t *)tablep)->guid;
 263                         table = ((efi_config_table_32_t *)tablep)->table;
 264                 }
 265
 266                 if (!match_config_table(&guid, table, common_tables))
 267                         match_config_table(&guid, table, arch_tables);
 268
 269                 tablep += sz;
 270         }
 271         pr_cont("\n");
 272         early_iounmap(config_tables, efi.systab->nr_tables * sz);
 273         return 0;
 274 }