1 // SPDX-License-Identifier: GPL-2.0
3 * Helper functions used by the EFI stub on multiple
4 * architectures. This should be #included by the EFI stub
5 * implementation files.
7 * Copyright 2011 Intel Corporation; author Matt Fleming
12 #include <linux/ctype.h>
13 #include <linux/efi.h>
14 #include <linux/kernel.h>
15 #include <linux/printk.h> /* For CONSOLE_LOGLEVEL_* */
17 #include <asm/setup.h>
22 bool efi_nokaslr = !IS_ENABLED(CONFIG_RANDOMIZE_BASE);
24 int efi_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
27 static bool efi_nosoftreserve;
28 static bool efi_disable_pci_dma = IS_ENABLED(CONFIG_EFI_DISABLE_PCI_DMA);
30 bool __pure __efi_soft_reserve_enabled(void)
32 return !efi_nosoftreserve;
36 * efi_char16_puts() - Write a UCS-2 encoded string to the console
37 * @str: UCS-2 encoded string
39 void efi_char16_puts(efi_char16_t *str)
41 efi_call_proto(efi_table_attr(efi_system_table, con_out),
46 u32 utf8_to_utf32(const u8 **s8)
54 * The position of the most-significant 0 bit gives us the length of
55 * a multi-octet encoding.
57 for (clen = 0; cx & 0x80; ++clen)
60 * If the 0 bit is in position 8, this is a valid single-octet
61 * encoding. If the 0 bit is in position 7 or positions 1-3, the
62 * encoding is invalid.
63 * In either case, we just return the first octet.
65 if (clen < 2 || clen > 4)
67 /* Get the bits from the first octet. */
69 for (i = 0; i < clen; ++i) {
70 /* Trailing octets must have 10 in most significant bits. */
74 c32 = (c32 << 6) | cx;
78 * - The character must be in the Unicode range.
79 * - It must not be a surrogate.
80 * - It must be encoded using the correct number of octets.
83 (c32 & 0xf800) == 0xd800 ||
84 clen != (c32 >= 0x80) + (c32 >= 0x800) + (c32 >= 0x10000))
91 * efi_puts() - Write a UTF-8 encoded string to the console
92 * @str: UTF-8 encoded string
94 void efi_puts(const char *str)
96 efi_char16_t buf[128];
97 size_t pos = 0, lim = ARRAY_SIZE(buf);
98 const u8 *s8 = (const u8 *)str;
104 c32 = utf8_to_utf32(&s8);
106 /* Characters in plane 0 use a single word. */
110 * Characters in other planes encode into a surrogate
113 buf[pos++] = (0xd800 - (0x10000 >> 10)) + (c32 >> 10);
114 buf[pos++] = 0xdc00 + (c32 & 0x3ff);
116 if (*s8 == '\0' || pos >= lim - 2) {
118 efi_char16_puts(buf);
125 * efi_printk() - Print a kernel message
126 * @fmt: format string
128 * The first letter of the format string is used to determine the logging level
129 * of the message. If the level is less then the current EFI logging level, the
130 * message is suppressed. The message will be truncated to 255 bytes.
132 * Return: number of printed characters
134 int efi_printk(const char *fmt, ...)
136 char printf_buf[256];
139 int loglevel = printk_get_level(fmt);
147 * Use loglevel -1 for cases where we just want to print to
154 if (loglevel >= efi_loglevel)
158 efi_puts("EFI stub: ");
160 fmt = printk_skip_level(fmt);
163 printed = vsnprintf(printf_buf, sizeof(printf_buf), fmt, args);
166 efi_puts(printf_buf);
167 if (printed >= sizeof(printf_buf)) {
168 efi_puts("[Message truncated]\n");
176 * efi_parse_options() - Parse EFI command line options
177 * @cmdline: kernel command line
179 * Parse the ASCII string @cmdline for EFI options, denoted by the efi=
180 * option, e.g. efi=nochunk.
182 * It should be noted that efi= is parsed in two very different
183 * environments, first in the early boot environment of the EFI boot
184 * stub, and subsequently during the kernel boot.
186 * Return: status code
188 efi_status_t efi_parse_options(char const *cmdline)
197 len = strnlen(cmdline, COMMAND_LINE_SIZE - 1) + 1;
198 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, len, (void **)&buf);
199 if (status != EFI_SUCCESS)
202 memcpy(buf, cmdline, len - 1);
204 str = skip_spaces(buf);
209 str = next_arg(str, ¶m, &val);
210 if (!val && !strcmp(param, "--"))
213 if (!strcmp(param, "nokaslr")) {
215 } else if (!strcmp(param, "quiet")) {
216 efi_loglevel = CONSOLE_LOGLEVEL_QUIET;
217 } else if (!strcmp(param, "noinitrd")) {
219 } else if (!strcmp(param, "efi") && val) {
220 efi_nochunk = parse_option_str(val, "nochunk");
221 efi_novamap = parse_option_str(val, "novamap");
223 efi_nosoftreserve = IS_ENABLED(CONFIG_EFI_SOFT_RESERVE) &&
224 parse_option_str(val, "nosoftreserve");
226 if (parse_option_str(val, "disable_early_pci_dma"))
227 efi_disable_pci_dma = true;
228 if (parse_option_str(val, "no_disable_early_pci_dma"))
229 efi_disable_pci_dma = false;
230 if (parse_option_str(val, "debug"))
231 efi_loglevel = CONSOLE_LOGLEVEL_DEBUG;
232 } else if (!strcmp(param, "video") &&
233 val && strstarts(val, "efifb:")) {
234 efi_parse_option_graphics(val + strlen("efifb:"));
237 efi_bs_call(free_pool, buf);
242 * The EFI_LOAD_OPTION descriptor has the following layout:
244 * u16 FilePathListLength;
246 * efi_device_path_protocol_t FilePathList[];
249 * This function validates and unpacks the variable-size data fields.
252 bool efi_load_option_unpack(efi_load_option_unpacked_t *dest,
253 const efi_load_option_t *src, size_t size)
257 efi_device_path_protocol_t header;
258 const efi_char16_t *description;
259 const efi_device_path_protocol_t *file_path_list;
261 if (size < offsetof(efi_load_option_t, variable_data))
263 pos = src->variable_data;
264 size -= offsetof(efi_load_option_t, variable_data);
266 if ((src->attributes & ~EFI_LOAD_OPTION_MASK) != 0)
269 /* Scan description. */
272 if (size < sizeof(c))
274 c = *(const u16 *)pos;
277 } while (c != L'\0');
279 /* Scan file_path_list. */
280 file_path_list = pos;
282 if (size < sizeof(header))
284 header = *(const efi_device_path_protocol_t *)pos;
285 if (header.length < sizeof(header))
287 if (size < header.length)
289 pos += header.length;
290 size -= header.length;
291 } while ((header.type != EFI_DEV_END_PATH && header.type != EFI_DEV_END_PATH2) ||
292 (header.sub_type != EFI_DEV_END_ENTIRE));
293 if (pos != (const void *)file_path_list + src->file_path_list_length)
296 dest->attributes = src->attributes;
297 dest->file_path_list_length = src->file_path_list_length;
298 dest->description = description;
299 dest->file_path_list = file_path_list;
300 dest->optional_data_size = size;
301 dest->optional_data = size ? pos : NULL;
307 * At least some versions of Dell firmware pass the entire contents of the
308 * Boot#### variable, i.e. the EFI_LOAD_OPTION descriptor, rather than just the
309 * OptionalData field.
311 * Detect this case and extract OptionalData.
313 void efi_apply_loadoptions_quirk(const void **load_options, int *load_options_size)
315 const efi_load_option_t *load_option = *load_options;
316 efi_load_option_unpacked_t load_option_unpacked;
318 if (!IS_ENABLED(CONFIG_X86))
322 if (*load_options_size < sizeof(*load_option))
324 if ((load_option->attributes & ~EFI_LOAD_OPTION_BOOT_MASK) != 0)
327 if (!efi_load_option_unpack(&load_option_unpacked, load_option, *load_options_size))
330 efi_warn_once(FW_BUG "LoadOptions is an EFI_LOAD_OPTION descriptor\n");
331 efi_warn_once(FW_BUG "Using OptionalData as a workaround\n");
333 *load_options = load_option_unpacked.optional_data;
334 *load_options_size = load_option_unpacked.optional_data_size;
338 * Convert the unicode UEFI command line to ASCII to pass to kernel.
339 * Size of memory allocated return in *cmd_line_len.
340 * Returns NULL on error.
342 char *efi_convert_cmdline(efi_loaded_image_t *image, int *cmd_line_len)
345 unsigned long cmdline_addr = 0;
346 int options_chars = efi_table_attr(image, load_options_size);
347 const u16 *options = efi_table_attr(image, load_options);
348 int options_bytes = 0, safe_options_bytes = 0; /* UTF-8 bytes */
349 bool in_quote = false;
352 efi_apply_loadoptions_quirk((const void **)&options, &options_chars);
353 options_chars /= sizeof(*options);
357 while (options_bytes < COMMAND_LINE_SIZE && options_chars--) {
361 if (c == L'\0' || c == L'\n')
364 in_quote = !in_quote;
365 else if (!in_quote && isspace((char)c))
366 safe_options_bytes = options_bytes;
373 * Get the number of UTF-8 bytes corresponding to a
375 * The first part handles everything in the BMP.
377 options_bytes += 2 + (c >= 0x800);
379 * Add one more byte for valid surrogate pairs. Invalid
380 * surrogates will be replaced with 0xfffd and take up
383 if ((c & 0xfc00) == 0xd800) {
385 * If the very last word is a high surrogate,
386 * we must ignore it since we can't access the
389 if (!options_chars) {
391 } else if ((*s2 & 0xfc00) == 0xdc00) {
398 if (options_bytes >= COMMAND_LINE_SIZE) {
399 options_bytes = safe_options_bytes;
400 efi_err("Command line is too long: truncated to %d bytes\n",
405 options_bytes++; /* NUL termination */
407 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, options_bytes,
408 (void **)&cmdline_addr);
409 if (status != EFI_SUCCESS)
412 snprintf((char *)cmdline_addr, options_bytes, "%.*ls",
413 options_bytes - 1, options);
415 *cmd_line_len = options_bytes;
416 return (char *)cmdline_addr;
420 * efi_exit_boot_services() - Exit boot services
421 * @handle: handle of the exiting image
422 * @map: pointer to receive the memory map
423 * @priv: argument to be passed to @priv_func
424 * @priv_func: function to process the memory map before exiting boot services
426 * Handle calling ExitBootServices according to the requirements set out by the
427 * spec. Obtains the current memory map, and returns that info after calling
428 * ExitBootServices. The client must specify a function to perform any
429 * processing of the memory map data prior to ExitBootServices. A client
430 * specific structure may be passed to the function via priv. The client
431 * function may be called multiple times.
433 * Return: status code
435 efi_status_t efi_exit_boot_services(void *handle,
436 struct efi_boot_memmap *map,
438 efi_exit_boot_map_processing priv_func)
442 status = efi_get_memory_map(map);
444 if (status != EFI_SUCCESS)
447 status = priv_func(map, priv);
448 if (status != EFI_SUCCESS)
451 if (efi_disable_pci_dma)
452 efi_pci_disable_bridge_busmaster();
454 status = efi_bs_call(exit_boot_services, handle, *map->key_ptr);
456 if (status == EFI_INVALID_PARAMETER) {
458 * The memory map changed between efi_get_memory_map() and
459 * exit_boot_services(). Per the UEFI Spec v2.6, Section 6.4:
460 * EFI_BOOT_SERVICES.ExitBootServices we need to get the
461 * updated map, and try again. The spec implies one retry
462 * should be sufficent, which is confirmed against the EDK2
463 * implementation. Per the spec, we can only invoke
464 * get_memory_map() and exit_boot_services() - we cannot alloc
465 * so efi_get_memory_map() cannot be used, and we must reuse
466 * the buffer. For all practical purposes, the headroom in the
467 * buffer should account for any changes in the map so the call
468 * to get_memory_map() is expected to succeed here.
470 *map->map_size = *map->buff_size;
471 status = efi_bs_call(get_memory_map,
478 /* exit_boot_services() was called, thus cannot free */
479 if (status != EFI_SUCCESS)
482 status = priv_func(map, priv);
483 /* exit_boot_services() was called, thus cannot free */
484 if (status != EFI_SUCCESS)
487 status = efi_bs_call(exit_boot_services, handle, *map->key_ptr);
490 /* exit_boot_services() was called, thus cannot free */
491 if (status != EFI_SUCCESS)
497 efi_bs_call(free_pool, *map->map);
503 * get_efi_config_table() - retrieve UEFI configuration table
504 * @guid: GUID of the configuration table to be retrieved
505 * Return: pointer to the configuration table or NULL
507 void *get_efi_config_table(efi_guid_t guid)
509 unsigned long tables = efi_table_attr(efi_system_table, tables);
510 int nr_tables = efi_table_attr(efi_system_table, nr_tables);
513 for (i = 0; i < nr_tables; i++) {
514 efi_config_table_t *t = (void *)tables;
516 if (efi_guidcmp(t->guid, guid) == 0)
517 return efi_table_attr(t, table);
519 tables += efi_is_native() ? sizeof(efi_config_table_t)
520 : sizeof(efi_config_table_32_t);
526 * The LINUX_EFI_INITRD_MEDIA_GUID vendor media device path below provides a way
527 * for the firmware or bootloader to expose the initrd data directly to the stub
528 * via the trivial LoadFile2 protocol, which is defined in the UEFI spec, and is
529 * very easy to implement. It is a simple Linux initrd specific conduit between
530 * kernel and firmware, allowing us to put the EFI stub (being part of the
531 * kernel) in charge of where and when to load the initrd, while leaving it up
532 * to the firmware to decide whether it needs to expose its filesystem hierarchy
535 static const struct {
536 struct efi_vendor_dev_path vendor;
537 struct efi_generic_dev_path end;
538 } __packed initrd_dev_path = {
542 EFI_DEV_MEDIA_VENDOR,
543 sizeof(struct efi_vendor_dev_path),
545 LINUX_EFI_INITRD_MEDIA_GUID
549 sizeof(struct efi_generic_dev_path)
554 * efi_load_initrd_dev_path() - load the initrd from the Linux initrd device path
555 * @load_addr: pointer to store the address where the initrd was loaded
556 * @load_size: pointer to store the size of the loaded initrd
557 * @max: upper limit for the initrd memory allocation
560 * * %EFI_SUCCESS if the initrd was loaded successfully, in which
561 * case @load_addr and @load_size are assigned accordingly
562 * * %EFI_NOT_FOUND if no LoadFile2 protocol exists on the initrd device path
563 * * %EFI_INVALID_PARAMETER if load_addr == NULL or load_size == NULL
564 * * %EFI_OUT_OF_RESOURCES if memory allocation failed
565 * * %EFI_LOAD_ERROR in all other cases
568 efi_status_t efi_load_initrd_dev_path(unsigned long *load_addr,
569 unsigned long *load_size,
572 efi_guid_t lf2_proto_guid = EFI_LOAD_FILE2_PROTOCOL_GUID;
573 efi_device_path_protocol_t *dp;
574 efi_load_file2_protocol_t *lf2;
575 unsigned long initrd_addr;
576 unsigned long initrd_size;
580 dp = (efi_device_path_protocol_t *)&initrd_dev_path;
581 status = efi_bs_call(locate_device_path, &lf2_proto_guid, &dp, &handle);
582 if (status != EFI_SUCCESS)
585 status = efi_bs_call(handle_protocol, handle, &lf2_proto_guid,
587 if (status != EFI_SUCCESS)
590 status = efi_call_proto(lf2, load_file, dp, false, &initrd_size, NULL);
591 if (status != EFI_BUFFER_TOO_SMALL)
592 return EFI_LOAD_ERROR;
594 status = efi_allocate_pages(initrd_size, &initrd_addr, max);
595 if (status != EFI_SUCCESS)
598 status = efi_call_proto(lf2, load_file, dp, false, &initrd_size,
599 (void *)initrd_addr);
600 if (status != EFI_SUCCESS) {
601 efi_free(initrd_size, initrd_addr);
602 return EFI_LOAD_ERROR;
605 *load_addr = initrd_addr;
606 *load_size = initrd_size;
611 efi_status_t efi_load_initrd_cmdline(efi_loaded_image_t *image,
612 unsigned long *load_addr,
613 unsigned long *load_size,
614 unsigned long soft_limit,
615 unsigned long hard_limit)
617 if (!IS_ENABLED(CONFIG_EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER) ||
618 (IS_ENABLED(CONFIG_X86) && (!efi_is_native() || image == NULL))) {
619 *load_addr = *load_size = 0;
623 return handle_cmdline_files(image, L"initrd=", sizeof(L"initrd=") - 2,
624 soft_limit, hard_limit,
625 load_addr, load_size);
629 * efi_load_initrd() - Load initial RAM disk
630 * @image: EFI loaded image protocol
631 * @load_addr: pointer to loaded initrd
632 * @load_size: size of loaded initrd
633 * @soft_limit: preferred size of allocated memory for loading the initrd
634 * @hard_limit: minimum size of allocated memory
636 * Return: status code
638 efi_status_t efi_load_initrd(efi_loaded_image_t *image,
639 unsigned long *load_addr,
640 unsigned long *load_size,
641 unsigned long soft_limit,
642 unsigned long hard_limit)
646 if (!load_addr || !load_size)
647 return EFI_INVALID_PARAMETER;
649 status = efi_load_initrd_dev_path(load_addr, load_size, hard_limit);
650 if (status == EFI_SUCCESS) {
651 efi_info("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n");
652 } else if (status == EFI_NOT_FOUND) {
653 status = efi_load_initrd_cmdline(image, load_addr, load_size,
654 soft_limit, hard_limit);
655 if (status == EFI_SUCCESS && *load_size > 0)
656 efi_info("Loaded initrd from command line option\n");
663 * efi_wait_for_key() - Wait for key stroke
664 * @usec: number of microseconds to wait for key stroke
667 * Wait for up to @usec microseconds for a key stroke.
669 * Return: status code, EFI_SUCCESS if key received
671 efi_status_t efi_wait_for_key(unsigned long usec, efi_input_key_t *key)
673 efi_event_t events[2], timer;
675 efi_simple_text_input_protocol_t *con_in;
678 con_in = efi_table_attr(efi_system_table, con_in);
680 return EFI_UNSUPPORTED;
681 efi_set_event_at(events, 0, efi_table_attr(con_in, wait_for_key));
683 status = efi_bs_call(create_event, EFI_EVT_TIMER, 0, NULL, NULL, &timer);
684 if (status != EFI_SUCCESS)
687 status = efi_bs_call(set_timer, timer, EfiTimerRelative,
688 EFI_100NSEC_PER_USEC * usec);
689 if (status != EFI_SUCCESS)
691 efi_set_event_at(events, 1, timer);
693 status = efi_bs_call(wait_for_event, 2, events, &index);
694 if (status == EFI_SUCCESS) {
696 status = efi_call_proto(con_in, read_keystroke, key);
698 status = EFI_TIMEOUT;
701 efi_bs_call(close_event, timer);