1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Helper functions used by the EFI stub on multiple 4 * architectures. This should be #included by the EFI stub 5 * implementation files. 6 * 7 * Copyright 2011 Intel Corporation; author Matt Fleming 8 */ 9 10 #include <linux/efi.h> 11 #include <asm/efi.h> 12 13 #include "efistub.h" 14 15 static bool __efistub_global efi_nochunk; 16 static bool __efistub_global efi_nokaslr; 17 static bool __efistub_global efi_noinitrd; 18 static bool __efistub_global efi_quiet; 19 static bool __efistub_global efi_novamap; 20 static bool __efistub_global efi_nosoftreserve; 21 static bool __efistub_global efi_disable_pci_dma = 22 IS_ENABLED(CONFIG_EFI_DISABLE_PCI_DMA); 23 24 bool __pure nochunk(void) 25 { 26 return efi_nochunk; 27 } 28 bool __pure nokaslr(void) 29 { 30 return efi_nokaslr; 31 } 32 bool __pure noinitrd(void) 33 { 34 return efi_noinitrd; 35 } 36 bool __pure is_quiet(void) 37 { 38 return efi_quiet; 39 } 40 bool __pure novamap(void) 41 { 42 return efi_novamap; 43 } 44 bool __pure __efi_soft_reserve_enabled(void) 45 { 46 return !efi_nosoftreserve; 47 } 48 49 void efi_printk(char *str) 50 { 51 char *s8; 52 53 for (s8 = str; *s8; s8++) { 54 efi_char16_t ch[2] = { 0 }; 55 56 ch[0] = *s8; 57 if (*s8 == '\n') { 58 efi_char16_t nl[2] = { '\r', 0 }; 59 efi_char16_printk(nl); 60 } 61 62 efi_char16_printk(ch); 63 } 64 } 65 66 /* 67 * Parse the ASCII string 'cmdline' for EFI options, denoted by the efi= 68 * option, e.g. efi=nochunk. 69 * 70 * It should be noted that efi= is parsed in two very different 71 * environments, first in the early boot environment of the EFI boot 72 * stub, and subsequently during the kernel boot. 73 */ 74 efi_status_t efi_parse_options(char const *cmdline) 75 { 76 size_t len = strlen(cmdline) + 1; 77 efi_status_t status; 78 char *str, *buf; 79 80 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, len, (void **)&buf); 81 if (status != EFI_SUCCESS) 82 return status; 83 84 str = skip_spaces(memcpy(buf, cmdline, len)); 85 86 while (*str) { 87 char *param, *val; 88 89 str = next_arg(str, ¶m, &val); 90 91 if (!strcmp(param, "nokaslr")) { 92 efi_nokaslr = true; 93 } else if (!strcmp(param, "quiet")) { 94 efi_quiet = true; 95 } else if (!strcmp(param, "noinitrd")) { 96 efi_noinitrd = true; 97 } else if (!strcmp(param, "efi") && val) { 98 efi_nochunk = parse_option_str(val, "nochunk"); 99 efi_novamap = parse_option_str(val, "novamap"); 100 101 efi_nosoftreserve = IS_ENABLED(CONFIG_EFI_SOFT_RESERVE) && 102 parse_option_str(val, "nosoftreserve"); 103 104 if (parse_option_str(val, "disable_early_pci_dma")) 105 efi_disable_pci_dma = true; 106 if (parse_option_str(val, "no_disable_early_pci_dma")) 107 efi_disable_pci_dma = false; 108 } 109 } 110 efi_bs_call(free_pool, buf); 111 return EFI_SUCCESS; 112 } 113 114 /* 115 * Get the number of UTF-8 bytes corresponding to an UTF-16 character. 116 * This overestimates for surrogates, but that is okay. 117 */ 118 static int efi_utf8_bytes(u16 c) 119 { 120 return 1 + (c >= 0x80) + (c >= 0x800); 121 } 122 123 /* 124 * Convert an UTF-16 string, not necessarily null terminated, to UTF-8. 125 */ 126 static u8 *efi_utf16_to_utf8(u8 *dst, const u16 *src, int n) 127 { 128 unsigned int c; 129 130 while (n--) { 131 c = *src++; 132 if (n && c >= 0xd800 && c <= 0xdbff && 133 *src >= 0xdc00 && *src <= 0xdfff) { 134 c = 0x10000 + ((c & 0x3ff) << 10) + (*src & 0x3ff); 135 src++; 136 n--; 137 } 138 if (c >= 0xd800 && c <= 0xdfff) 139 c = 0xfffd; /* Unmatched surrogate */ 140 if (c < 0x80) { 141 *dst++ = c; 142 continue; 143 } 144 if (c < 0x800) { 145 *dst++ = 0xc0 + (c >> 6); 146 goto t1; 147 } 148 if (c < 0x10000) { 149 *dst++ = 0xe0 + (c >> 12); 150 goto t2; 151 } 152 *dst++ = 0xf0 + (c >> 18); 153 *dst++ = 0x80 + ((c >> 12) & 0x3f); 154 t2: 155 *dst++ = 0x80 + ((c >> 6) & 0x3f); 156 t1: 157 *dst++ = 0x80 + (c & 0x3f); 158 } 159 160 return dst; 161 } 162 163 /* 164 * Convert the unicode UEFI command line to ASCII to pass to kernel. 165 * Size of memory allocated return in *cmd_line_len. 166 * Returns NULL on error. 167 */ 168 char *efi_convert_cmdline(efi_loaded_image_t *image, 169 int *cmd_line_len, unsigned long max_addr) 170 { 171 const u16 *s2; 172 u8 *s1 = NULL; 173 unsigned long cmdline_addr = 0; 174 int load_options_chars = efi_table_attr(image, load_options_size) / 2; 175 const u16 *options = efi_table_attr(image, load_options); 176 int options_bytes = 0; /* UTF-8 bytes */ 177 int options_chars = 0; /* UTF-16 chars */ 178 efi_status_t status; 179 u16 zero = 0; 180 181 if (options) { 182 s2 = options; 183 while (*s2 && *s2 != '\n' 184 && options_chars < load_options_chars) { 185 options_bytes += efi_utf8_bytes(*s2++); 186 options_chars++; 187 } 188 } 189 190 if (!options_chars) { 191 /* No command line options, so return empty string*/ 192 options = &zero; 193 } 194 195 options_bytes++; /* NUL termination */ 196 197 status = efi_allocate_pages(options_bytes, &cmdline_addr, max_addr); 198 if (status != EFI_SUCCESS) 199 return NULL; 200 201 s1 = (u8 *)cmdline_addr; 202 s2 = (const u16 *)options; 203 204 s1 = efi_utf16_to_utf8(s1, s2, options_chars); 205 *s1 = '\0'; 206 207 *cmd_line_len = options_bytes; 208 return (char *)cmdline_addr; 209 } 210 211 /* 212 * Handle calling ExitBootServices according to the requirements set out by the 213 * spec. Obtains the current memory map, and returns that info after calling 214 * ExitBootServices. The client must specify a function to perform any 215 * processing of the memory map data prior to ExitBootServices. A client 216 * specific structure may be passed to the function via priv. The client 217 * function may be called multiple times. 218 */ 219 efi_status_t efi_exit_boot_services(void *handle, 220 struct efi_boot_memmap *map, 221 void *priv, 222 efi_exit_boot_map_processing priv_func) 223 { 224 efi_status_t status; 225 226 status = efi_get_memory_map(map); 227 228 if (status != EFI_SUCCESS) 229 goto fail; 230 231 status = priv_func(map, priv); 232 if (status != EFI_SUCCESS) 233 goto free_map; 234 235 if (efi_disable_pci_dma) 236 efi_pci_disable_bridge_busmaster(); 237 238 status = efi_bs_call(exit_boot_services, handle, *map->key_ptr); 239 240 if (status == EFI_INVALID_PARAMETER) { 241 /* 242 * The memory map changed between efi_get_memory_map() and 243 * exit_boot_services(). Per the UEFI Spec v2.6, Section 6.4: 244 * EFI_BOOT_SERVICES.ExitBootServices we need to get the 245 * updated map, and try again. The spec implies one retry 246 * should be sufficent, which is confirmed against the EDK2 247 * implementation. Per the spec, we can only invoke 248 * get_memory_map() and exit_boot_services() - we cannot alloc 249 * so efi_get_memory_map() cannot be used, and we must reuse 250 * the buffer. For all practical purposes, the headroom in the 251 * buffer should account for any changes in the map so the call 252 * to get_memory_map() is expected to succeed here. 253 */ 254 *map->map_size = *map->buff_size; 255 status = efi_bs_call(get_memory_map, 256 map->map_size, 257 *map->map, 258 map->key_ptr, 259 map->desc_size, 260 map->desc_ver); 261 262 /* exit_boot_services() was called, thus cannot free */ 263 if (status != EFI_SUCCESS) 264 goto fail; 265 266 status = priv_func(map, priv); 267 /* exit_boot_services() was called, thus cannot free */ 268 if (status != EFI_SUCCESS) 269 goto fail; 270 271 status = efi_bs_call(exit_boot_services, handle, *map->key_ptr); 272 } 273 274 /* exit_boot_services() was called, thus cannot free */ 275 if (status != EFI_SUCCESS) 276 goto fail; 277 278 return EFI_SUCCESS; 279 280 free_map: 281 efi_bs_call(free_pool, *map->map); 282 fail: 283 return status; 284 } 285 286 void *get_efi_config_table(efi_guid_t guid) 287 { 288 unsigned long tables = efi_table_attr(efi_system_table(), tables); 289 int nr_tables = efi_table_attr(efi_system_table(), nr_tables); 290 int i; 291 292 for (i = 0; i < nr_tables; i++) { 293 efi_config_table_t *t = (void *)tables; 294 295 if (efi_guidcmp(t->guid, guid) == 0) 296 return efi_table_attr(t, table); 297 298 tables += efi_is_native() ? sizeof(efi_config_table_t) 299 : sizeof(efi_config_table_32_t); 300 } 301 return NULL; 302 } 303 304 void efi_char16_printk(efi_char16_t *str) 305 { 306 efi_call_proto(efi_table_attr(efi_system_table(), con_out), 307 output_string, str); 308 } 309 310 /* 311 * The LINUX_EFI_INITRD_MEDIA_GUID vendor media device path below provides a way 312 * for the firmware or bootloader to expose the initrd data directly to the stub 313 * via the trivial LoadFile2 protocol, which is defined in the UEFI spec, and is 314 * very easy to implement. It is a simple Linux initrd specific conduit between 315 * kernel and firmware, allowing us to put the EFI stub (being part of the 316 * kernel) in charge of where and when to load the initrd, while leaving it up 317 * to the firmware to decide whether it needs to expose its filesystem hierarchy 318 * via EFI protocols. 319 */ 320 static const struct { 321 struct efi_vendor_dev_path vendor; 322 struct efi_generic_dev_path end; 323 } __packed initrd_dev_path = { 324 { 325 { 326 EFI_DEV_MEDIA, 327 EFI_DEV_MEDIA_VENDOR, 328 sizeof(struct efi_vendor_dev_path), 329 }, 330 LINUX_EFI_INITRD_MEDIA_GUID 331 }, { 332 EFI_DEV_END_PATH, 333 EFI_DEV_END_ENTIRE, 334 sizeof(struct efi_generic_dev_path) 335 } 336 }; 337 338 /** 339 * efi_load_initrd_dev_path - load the initrd from the Linux initrd device path 340 * @load_addr: pointer to store the address where the initrd was loaded 341 * @load_size: pointer to store the size of the loaded initrd 342 * @max: upper limit for the initrd memory allocation 343 * @return: %EFI_SUCCESS if the initrd was loaded successfully, in which 344 * case @load_addr and @load_size are assigned accordingly 345 * %EFI_NOT_FOUND if no LoadFile2 protocol exists on the initrd 346 * device path 347 * %EFI_INVALID_PARAMETER if load_addr == NULL or load_size == NULL 348 * %EFI_OUT_OF_RESOURCES if memory allocation failed 349 * %EFI_LOAD_ERROR in all other cases 350 */ 351 efi_status_t efi_load_initrd_dev_path(unsigned long *load_addr, 352 unsigned long *load_size, 353 unsigned long max) 354 { 355 efi_guid_t lf2_proto_guid = EFI_LOAD_FILE2_PROTOCOL_GUID; 356 efi_device_path_protocol_t *dp; 357 efi_load_file2_protocol_t *lf2; 358 unsigned long initrd_addr; 359 unsigned long initrd_size; 360 efi_handle_t handle; 361 efi_status_t status; 362 363 if (!load_addr || !load_size) 364 return EFI_INVALID_PARAMETER; 365 366 dp = (efi_device_path_protocol_t *)&initrd_dev_path; 367 status = efi_bs_call(locate_device_path, &lf2_proto_guid, &dp, &handle); 368 if (status != EFI_SUCCESS) 369 return status; 370 371 status = efi_bs_call(handle_protocol, handle, &lf2_proto_guid, 372 (void **)&lf2); 373 if (status != EFI_SUCCESS) 374 return status; 375 376 status = efi_call_proto(lf2, load_file, dp, false, &initrd_size, NULL); 377 if (status != EFI_BUFFER_TOO_SMALL) 378 return EFI_LOAD_ERROR; 379 380 status = efi_allocate_pages(initrd_size, &initrd_addr, max); 381 if (status != EFI_SUCCESS) 382 return status; 383 384 status = efi_call_proto(lf2, load_file, dp, false, &initrd_size, 385 (void *)initrd_addr); 386 if (status != EFI_SUCCESS) { 387 efi_free(initrd_size, initrd_addr); 388 return EFI_LOAD_ERROR; 389 } 390 391 *load_addr = initrd_addr; 392 *load_size = initrd_size; 393 return EFI_SUCCESS; 394 } 395