1 #define pr_fmt(fmt) "efi: " fmt 2 3 #include <linux/init.h> 4 #include <linux/kernel.h> 5 #include <linux/string.h> 6 #include <linux/time.h> 7 #include <linux/types.h> 8 #include <linux/efi.h> 9 #include <linux/slab.h> 10 #include <linux/memblock.h> 11 #include <linux/bootmem.h> 12 #include <linux/acpi.h> 13 #include <linux/dmi.h> 14 #include <asm/efi.h> 15 #include <asm/uv/uv.h> 16 17 #define EFI_MIN_RESERVE 5120 18 19 #define EFI_DUMMY_GUID \ 20 EFI_GUID(0x4424ac57, 0xbe4b, 0x47dd, 0x9e, 0x97, 0xed, 0x50, 0xf0, 0x9f, 0x92, 0xa9) 21 22 static efi_char16_t efi_dummy_name[6] = { 'D', 'U', 'M', 'M', 'Y', 0 }; 23 24 static bool efi_no_storage_paranoia; 25 26 /* 27 * Some firmware implementations refuse to boot if there's insufficient 28 * space in the variable store. The implementation of garbage collection 29 * in some FW versions causes stale (deleted) variables to take up space 30 * longer than intended and space is only freed once the store becomes 31 * almost completely full. 32 * 33 * Enabling this option disables the space checks in 34 * efi_query_variable_store() and forces garbage collection. 35 * 36 * Only enable this option if deleting EFI variables does not free up 37 * space in your variable store, e.g. if despite deleting variables 38 * you're unable to create new ones. 39 */ 40 static int __init setup_storage_paranoia(char *arg) 41 { 42 efi_no_storage_paranoia = true; 43 return 0; 44 } 45 early_param("efi_no_storage_paranoia", setup_storage_paranoia); 46 47 /* 48 * Deleting the dummy variable which kicks off garbage collection 49 */ 50 void efi_delete_dummy_variable(void) 51 { 52 efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID, 53 EFI_VARIABLE_NON_VOLATILE | 54 EFI_VARIABLE_BOOTSERVICE_ACCESS | 55 EFI_VARIABLE_RUNTIME_ACCESS, 56 0, NULL); 57 } 58 59 /* 60 * In the nonblocking case we do not attempt to perform garbage 61 * collection if we do not have enough free space. Rather, we do the 62 * bare minimum check and give up immediately if the available space 63 * is below EFI_MIN_RESERVE. 64 * 65 * This function is intended to be small and simple because it is 66 * invoked from crash handler paths. 67 */ 68 static efi_status_t 69 query_variable_store_nonblocking(u32 attributes, unsigned long size) 70 { 71 efi_status_t status; 72 u64 storage_size, remaining_size, max_size; 73 74 status = efi.query_variable_info_nonblocking(attributes, &storage_size, 75 &remaining_size, 76 &max_size); 77 if (status != EFI_SUCCESS) 78 return status; 79 80 if (remaining_size - size < EFI_MIN_RESERVE) 81 return EFI_OUT_OF_RESOURCES; 82 83 return EFI_SUCCESS; 84 } 85 86 /* 87 * Some firmware implementations refuse to boot if there's insufficient space 88 * in the variable store. Ensure that we never use more than a safe limit. 89 * 90 * Return EFI_SUCCESS if it is safe to write 'size' bytes to the variable 91 * store. 92 */ 93 efi_status_t efi_query_variable_store(u32 attributes, unsigned long size, 94 bool nonblocking) 95 { 96 efi_status_t status; 97 u64 storage_size, remaining_size, max_size; 98 99 if (!(attributes & EFI_VARIABLE_NON_VOLATILE)) 100 return 0; 101 102 if (nonblocking) 103 return query_variable_store_nonblocking(attributes, size); 104 105 status = efi.query_variable_info(attributes, &storage_size, 106 &remaining_size, &max_size); 107 if (status != EFI_SUCCESS) 108 return status; 109 110 /* 111 * We account for that by refusing the write if permitting it would 112 * reduce the available space to under 5KB. This figure was provided by 113 * Samsung, so should be safe. 114 */ 115 if ((remaining_size - size < EFI_MIN_RESERVE) && 116 !efi_no_storage_paranoia) { 117 118 /* 119 * Triggering garbage collection may require that the firmware 120 * generate a real EFI_OUT_OF_RESOURCES error. We can force 121 * that by attempting to use more space than is available. 122 */ 123 unsigned long dummy_size = remaining_size + 1024; 124 void *dummy = kzalloc(dummy_size, GFP_ATOMIC); 125 126 if (!dummy) 127 return EFI_OUT_OF_RESOURCES; 128 129 status = efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID, 130 EFI_VARIABLE_NON_VOLATILE | 131 EFI_VARIABLE_BOOTSERVICE_ACCESS | 132 EFI_VARIABLE_RUNTIME_ACCESS, 133 dummy_size, dummy); 134 135 if (status == EFI_SUCCESS) { 136 /* 137 * This should have failed, so if it didn't make sure 138 * that we delete it... 139 */ 140 efi_delete_dummy_variable(); 141 } 142 143 kfree(dummy); 144 145 /* 146 * The runtime code may now have triggered a garbage collection 147 * run, so check the variable info again 148 */ 149 status = efi.query_variable_info(attributes, &storage_size, 150 &remaining_size, &max_size); 151 152 if (status != EFI_SUCCESS) 153 return status; 154 155 /* 156 * There still isn't enough room, so return an error 157 */ 158 if (remaining_size - size < EFI_MIN_RESERVE) 159 return EFI_OUT_OF_RESOURCES; 160 } 161 162 return EFI_SUCCESS; 163 } 164 EXPORT_SYMBOL_GPL(efi_query_variable_store); 165 166 /* 167 * Helper function for efi_reserve_boot_services() to figure out if we 168 * can free regions in efi_free_boot_services(). 169 * 170 * Use this function to ensure we do not free regions owned by somebody 171 * else. We must only reserve (and then free) regions: 172 * 173 * - Not within any part of the kernel 174 * - Not the BIOS reserved area (E820_RESERVED, E820_NVS, etc) 175 */ 176 static bool can_free_region(u64 start, u64 size) 177 { 178 if (start + size > __pa_symbol(_text) && start <= __pa_symbol(_end)) 179 return false; 180 181 if (!e820_all_mapped(start, start+size, E820_RAM)) 182 return false; 183 184 return true; 185 } 186 187 /* 188 * The UEFI specification makes it clear that the operating system is free to do 189 * whatever it wants with boot services code after ExitBootServices() has been 190 * called. Ignoring this recommendation a significant bunch of EFI implementations 191 * continue calling into boot services code (SetVirtualAddressMap). In order to 192 * work around such buggy implementations we reserve boot services region during 193 * EFI init and make sure it stays executable. Then, after SetVirtualAddressMap(), it 194 * is discarded. 195 */ 196 void __init efi_reserve_boot_services(void) 197 { 198 void *p; 199 200 for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) { 201 efi_memory_desc_t *md = p; 202 u64 start = md->phys_addr; 203 u64 size = md->num_pages << EFI_PAGE_SHIFT; 204 bool already_reserved; 205 206 if (md->type != EFI_BOOT_SERVICES_CODE && 207 md->type != EFI_BOOT_SERVICES_DATA) 208 continue; 209 210 already_reserved = memblock_is_region_reserved(start, size); 211 212 /* 213 * Because the following memblock_reserve() is paired 214 * with free_bootmem_late() for this region in 215 * efi_free_boot_services(), we must be extremely 216 * careful not to reserve, and subsequently free, 217 * critical regions of memory (like the kernel image) or 218 * those regions that somebody else has already 219 * reserved. 220 * 221 * A good example of a critical region that must not be 222 * freed is page zero (first 4Kb of memory), which may 223 * contain boot services code/data but is marked 224 * E820_RESERVED by trim_bios_range(). 225 */ 226 if (!already_reserved) { 227 memblock_reserve(start, size); 228 229 /* 230 * If we are the first to reserve the region, no 231 * one else cares about it. We own it and can 232 * free it later. 233 */ 234 if (can_free_region(start, size)) 235 continue; 236 } 237 238 /* 239 * We don't own the region. We must not free it. 240 * 241 * Setting this bit for a boot services region really 242 * doesn't make sense as far as the firmware is 243 * concerned, but it does provide us with a way to tag 244 * those regions that must not be paired with 245 * free_bootmem_late(). 246 */ 247 md->attribute |= EFI_MEMORY_RUNTIME; 248 } 249 } 250 251 void __init efi_free_boot_services(void) 252 { 253 void *p; 254 255 for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) { 256 efi_memory_desc_t *md = p; 257 unsigned long long start = md->phys_addr; 258 unsigned long long size = md->num_pages << EFI_PAGE_SHIFT; 259 260 if (md->type != EFI_BOOT_SERVICES_CODE && 261 md->type != EFI_BOOT_SERVICES_DATA) 262 continue; 263 264 /* Do not free, someone else owns it: */ 265 if (md->attribute & EFI_MEMORY_RUNTIME) 266 continue; 267 268 free_bootmem_late(start, size); 269 } 270 271 efi_unmap_memmap(); 272 } 273 274 /* 275 * A number of config table entries get remapped to virtual addresses 276 * after entering EFI virtual mode. However, the kexec kernel requires 277 * their physical addresses therefore we pass them via setup_data and 278 * correct those entries to their respective physical addresses here. 279 * 280 * Currently only handles smbios which is necessary for some firmware 281 * implementation. 282 */ 283 int __init efi_reuse_config(u64 tables, int nr_tables) 284 { 285 int i, sz, ret = 0; 286 void *p, *tablep; 287 struct efi_setup_data *data; 288 289 if (!efi_setup) 290 return 0; 291 292 if (!efi_enabled(EFI_64BIT)) 293 return 0; 294 295 data = early_memremap(efi_setup, sizeof(*data)); 296 if (!data) { 297 ret = -ENOMEM; 298 goto out; 299 } 300 301 if (!data->smbios) 302 goto out_memremap; 303 304 sz = sizeof(efi_config_table_64_t); 305 306 p = tablep = early_memremap(tables, nr_tables * sz); 307 if (!p) { 308 pr_err("Could not map Configuration table!\n"); 309 ret = -ENOMEM; 310 goto out_memremap; 311 } 312 313 for (i = 0; i < efi.systab->nr_tables; i++) { 314 efi_guid_t guid; 315 316 guid = ((efi_config_table_64_t *)p)->guid; 317 318 if (!efi_guidcmp(guid, SMBIOS_TABLE_GUID)) 319 ((efi_config_table_64_t *)p)->table = data->smbios; 320 p += sz; 321 } 322 early_memunmap(tablep, nr_tables * sz); 323 324 out_memremap: 325 early_memunmap(data, sizeof(*data)); 326 out: 327 return ret; 328 } 329 330 static const struct dmi_system_id sgi_uv1_dmi[] = { 331 { NULL, "SGI UV1", 332 { DMI_MATCH(DMI_PRODUCT_NAME, "Stoutland Platform"), 333 DMI_MATCH(DMI_PRODUCT_VERSION, "1.0"), 334 DMI_MATCH(DMI_BIOS_VENDOR, "SGI.COM"), 335 } 336 }, 337 { } /* NULL entry stops DMI scanning */ 338 }; 339 340 void __init efi_apply_memmap_quirks(void) 341 { 342 /* 343 * Once setup is done earlier, unmap the EFI memory map on mismatched 344 * firmware/kernel architectures since there is no support for runtime 345 * services. 346 */ 347 if (!efi_runtime_supported()) { 348 pr_info("Setup done, disabling due to 32/64-bit mismatch\n"); 349 efi_unmap_memmap(); 350 } 351 352 /* UV2+ BIOS has a fix for this issue. UV1 still needs the quirk. */ 353 if (dmi_check_system(sgi_uv1_dmi)) 354 set_bit(EFI_OLD_MEMMAP, &efi.flags); 355 } 356 357 /* 358 * For most modern platforms the preferred method of powering off is via 359 * ACPI. However, there are some that are known to require the use of 360 * EFI runtime services and for which ACPI does not work at all. 361 * 362 * Using EFI is a last resort, to be used only if no other option 363 * exists. 364 */ 365 bool efi_reboot_required(void) 366 { 367 if (!acpi_gbl_reduced_hardware) 368 return false; 369 370 efi_reboot_quirk_mode = EFI_RESET_WARM; 371 return true; 372 } 373 374 bool efi_poweroff_required(void) 375 { 376 return !!acpi_gbl_reduced_hardware; 377 } 378