drivers/firmware/efi/libstub/efi-stub-helper.c

   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/stdarg.h>
  11
  12 #include <linux/efi.h>
  13 #include <linux/kernel.h>
  14 #include <asm/efi.h>
  15 #include <asm/setup.h>
  16
  17 #include "efistub.h"
  18
  19 bool efi_nochunk;
  20 bool efi_nokaslr = !IS_ENABLED(CONFIG_RANDOMIZE_BASE);
  21 bool efi_novamap;
  22
  23 static bool efi_noinitrd;
  24 static bool efi_nosoftreserve;
  25 static bool efi_disable_pci_dma = IS_ENABLED(CONFIG_EFI_DISABLE_PCI_DMA);
  26
  27 bool __pure __efi_soft_reserve_enabled(void)
  28 {
  29         return !efi_nosoftreserve;
  30 }
  31
  32 /**
  33  * efi_parse_options() - Parse EFI command line options
  34  * @cmdline:    kernel command line
  35  *
  36  * Parse the ASCII string @cmdline for EFI options, denoted by the efi=
  37  * option, e.g. efi=nochunk.
  38  *
  39  * It should be noted that efi= is parsed in two very different
  40  * environments, first in the early boot environment of the EFI boot
  41  * stub, and subsequently during the kernel boot.
  42  *
  43  * Return:      status code
  44  */
  45 efi_status_t efi_parse_options(char const *cmdline)
  46 {
  47         size_t len;
  48         efi_status_t status;
  49         char *str, *buf;
  50
  51         if (!cmdline)
  52                 return EFI_SUCCESS;
  53
  54         len = strnlen(cmdline, COMMAND_LINE_SIZE - 1) + 1;
  55         status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, len, (void **)&buf);
  56         if (status != EFI_SUCCESS)
  57                 return status;
  58
  59         memcpy(buf, cmdline, len - 1);
  60         buf[len - 1] = '\0';
  61         str = skip_spaces(buf);
  62
  63         while (*str) {
  64                 char *param, *val;
  65
  66                 str = next_arg(str, &param, &val);
  67                 if (!val && !strcmp(param, "--"))
  68                         break;
  69
  70                 if (!strcmp(param, "nokaslr")) {
  71                         efi_nokaslr = true;
  72                 } else if (!strcmp(param, "quiet")) {
  73                         efi_loglevel = CONSOLE_LOGLEVEL_QUIET;
  74                 } else if (!strcmp(param, "noinitrd")) {
  75                         efi_noinitrd = true;
  76                 } else if (IS_ENABLED(CONFIG_X86_64) && !strcmp(param, "no5lvl")) {
  77                         efi_no5lvl = true;
  78                 } else if (!strcmp(param, "efi") && val) {
  79                         efi_nochunk = parse_option_str(val, "nochunk");
  80                         efi_novamap |= parse_option_str(val, "novamap");
  81
  82                         efi_nosoftreserve = IS_ENABLED(CONFIG_EFI_SOFT_RESERVE) &&
  83                                             parse_option_str(val, "nosoftreserve");
  84
  85                         if (parse_option_str(val, "disable_early_pci_dma"))
  86                                 efi_disable_pci_dma = true;
  87                         if (parse_option_str(val, "no_disable_early_pci_dma"))
  88                                 efi_disable_pci_dma = false;
  89                         if (parse_option_str(val, "debug"))
  90                                 efi_loglevel = CONSOLE_LOGLEVEL_DEBUG;
  91                 } else if (!strcmp(param, "video") &&
  92                            val && strstarts(val, "efifb:")) {
  93                         efi_parse_option_graphics(val + strlen("efifb:"));
  94                 }
  95         }
  96         efi_bs_call(free_pool, buf);
  97         return EFI_SUCCESS;
  98 }
  99
 100 /*
 101  * The EFI_LOAD_OPTION descriptor has the following layout:
 102  *      u32 Attributes;
 103  *      u16 FilePathListLength;
 104  *      u16 Description[];
 105  *      efi_device_path_protocol_t FilePathList[];
 106  *      u8 OptionalData[];
 107  *
 108  * This function validates and unpacks the variable-size data fields.
 109  */
 110 static
 111 bool efi_load_option_unpack(efi_load_option_unpacked_t *dest,
 112                             const efi_load_option_t *src, size_t size)
 113 {
 114         const void *pos;
 115         u16 c;
 116         efi_device_path_protocol_t header;
 117         const efi_char16_t *description;
 118         const efi_device_path_protocol_t *file_path_list;
 119
 120         if (size < offsetof(efi_load_option_t, variable_data))
 121                 return false;
 122         pos = src->variable_data;
 123         size -= offsetof(efi_load_option_t, variable_data);
 124
 125         if ((src->attributes & ~EFI_LOAD_OPTION_MASK) != 0)
 126                 return false;
 127
 128         /* Scan description. */
 129         description = pos;
 130         do {
 131                 if (size < sizeof(c))
 132                         return false;
 133                 c = *(const u16 *)pos;
 134                 pos += sizeof(c);
 135                 size -= sizeof(c);
 136         } while (c != L'\0');
 137
 138         /* Scan file_path_list. */
 139         file_path_list = pos;
 140         do {
 141                 if (size < sizeof(header))
 142                         return false;
 143                 header = *(const efi_device_path_protocol_t *)pos;
 144                 if (header.length < sizeof(header))
 145                         return false;
 146                 if (size < header.length)
 147                         return false;
 148                 pos += header.length;
 149                 size -= header.length;
 150         } while ((header.type != EFI_DEV_END_PATH && header.type != EFI_DEV_END_PATH2) ||
 151                  (header.sub_type != EFI_DEV_END_ENTIRE));
 152         if (pos != (const void *)file_path_list + src->file_path_list_length)
 153                 return false;
 154
 155         dest->attributes = src->attributes;
 156         dest->file_path_list_length = src->file_path_list_length;
 157         dest->description = description;
 158         dest->file_path_list = file_path_list;
 159         dest->optional_data_size = size;
 160         dest->optional_data = size ? pos : NULL;
 161
 162         return true;
 163 }
 164
 165 /*
 166  * At least some versions of Dell firmware pass the entire contents of the
 167  * Boot#### variable, i.e. the EFI_LOAD_OPTION descriptor, rather than just the
 168  * OptionalData field.
 169  *
 170  * Detect this case and extract OptionalData.
 171  */
 172 void efi_apply_loadoptions_quirk(const void **load_options, u32 *load_options_size)
 173 {
 174         const efi_load_option_t *load_option = *load_options;
 175         efi_load_option_unpacked_t load_option_unpacked;
 176
 177         if (!IS_ENABLED(CONFIG_X86))
 178                 return;
 179         if (!load_option)
 180                 return;
 181         if (*load_options_size < sizeof(*load_option))
 182                 return;
 183         if ((load_option->attributes & ~EFI_LOAD_OPTION_BOOT_MASK) != 0)
 184                 return;
 185
 186         if (!efi_load_option_unpack(&load_option_unpacked, load_option, *load_options_size))
 187                 return;
 188
 189         efi_warn_once(FW_BUG "LoadOptions is an EFI_LOAD_OPTION descriptor\n");
 190         efi_warn_once(FW_BUG "Using OptionalData as a workaround\n");
 191
 192         *load_options = load_option_unpacked.optional_data;
 193         *load_options_size = load_option_unpacked.optional_data_size;
 194 }
 195
 196 enum efistub_event {
 197         EFISTUB_EVT_INITRD,
 198         EFISTUB_EVT_LOAD_OPTIONS,
 199         EFISTUB_EVT_COUNT,
 200 };
 201
 202 #define STR_WITH_SIZE(s)        sizeof(s), s
 203
 204 static const struct {
 205         u32             pcr_index;
 206         u32             event_id;
 207         u32             event_data_len;
 208         u8              event_data[52];
 209 } events[] = {
 210         [EFISTUB_EVT_INITRD] = {
 211                 9,
 212                 INITRD_EVENT_TAG_ID,
 213                 STR_WITH_SIZE("Linux initrd")
 214         },
 215         [EFISTUB_EVT_LOAD_OPTIONS] = {
 216                 9,
 217                 LOAD_OPTIONS_EVENT_TAG_ID,
 218                 STR_WITH_SIZE("LOADED_IMAGE::LoadOptions")
 219         },
 220 };
 221
 222 static efi_status_t efi_measure_tagged_event(unsigned long load_addr,
 223                                              unsigned long load_size,
 224                                              enum efistub_event event)
 225 {
 226         efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;
 227         efi_tcg2_protocol_t *tcg2 = NULL;
 228         efi_status_t status;
 229
 230         efi_bs_call(locate_protocol, &tcg2_guid, NULL, (void **)&tcg2);
 231         if (tcg2) {
 232                 struct efi_measured_event {
 233                         efi_tcg2_event_t        event_data;
 234                         efi_tcg2_tagged_event_t tagged_event;
 235                         u8                      tagged_event_data[];
 236                 } *evt;
 237                 int size = sizeof(*evt) + events[event].event_data_len;
 238
 239                 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
 240                                      (void **)&evt);
 241                 if (status != EFI_SUCCESS)
 242                         goto fail;
 243
 244                 evt->event_data = (struct efi_tcg2_event){
 245                         .event_size                     = size,
 246                         .event_header.header_size       = sizeof(evt->event_data.event_header),
 247                         .event_header.header_version    = EFI_TCG2_EVENT_HEADER_VERSION,
 248                         .event_header.pcr_index         = events[event].pcr_index,
 249                         .event_header.event_type        = EV_EVENT_TAG,
 250                 };
 251
 252                 evt->tagged_event = (struct efi_tcg2_tagged_event){
 253                         .tagged_event_id                = events[event].event_id,
 254                         .tagged_event_data_size         = events[event].event_data_len,
 255                 };
 256
 257                 memcpy(evt->tagged_event_data, events[event].event_data,
 258                        events[event].event_data_len);
 259
 260                 status = efi_call_proto(tcg2, hash_log_extend_event, 0,
 261                                         load_addr, load_size, &evt->event_data);
 262                 efi_bs_call(free_pool, evt);
 263
 264                 if (status != EFI_SUCCESS)
 265                         goto fail;
 266                 return EFI_SUCCESS;
 267         }
 268
 269         return EFI_UNSUPPORTED;
 270 fail:
 271         efi_warn("Failed to measure data for event %d: 0x%lx\n", event, status);
 272         return status;
 273 }
 274
 275 /*
 276  * Convert the unicode UEFI command line to ASCII to pass to kernel.
 277  * Size of memory allocated return in *cmd_line_len.
 278  * Returns NULL on error.
 279  */
 280 char *efi_convert_cmdline(efi_loaded_image_t *image, int *cmd_line_len)
 281 {
 282         const efi_char16_t *options = efi_table_attr(image, load_options);
 283         u32 options_size = efi_table_attr(image, load_options_size);
 284         int options_bytes = 0, safe_options_bytes = 0;  /* UTF-8 bytes */
 285         unsigned long cmdline_addr = 0;
 286         const efi_char16_t *s2;
 287         bool in_quote = false;
 288         efi_status_t status;
 289         u32 options_chars;
 290
 291         if (options_size > 0)
 292                 efi_measure_tagged_event((unsigned long)options, options_size,
 293                                          EFISTUB_EVT_LOAD_OPTIONS);
 294
 295         efi_apply_loadoptions_quirk((const void **)&options, &options_size);
 296         options_chars = options_size / sizeof(efi_char16_t);
 297
 298         if (options) {
 299                 s2 = options;
 300                 while (options_bytes < COMMAND_LINE_SIZE && options_chars--) {
 301                         efi_char16_t c = *s2++;
 302
 303                         if (c < 0x80) {
 304                                 if (c == L'\0' || c == L'\n')
 305                                         break;
 306                                 if (c == L'"')
 307                                         in_quote = !in_quote;
 308                                 else if (!in_quote && isspace((char)c))
 309                                         safe_options_bytes = options_bytes;
 310
 311                                 options_bytes++;
 312                                 continue;
 313                         }
 314
 315                         /*
 316                          * Get the number of UTF-8 bytes corresponding to a
 317                          * UTF-16 character.
 318                          * The first part handles everything in the BMP.
 319                          */
 320                         options_bytes += 2 + (c >= 0x800);
 321                         /*
 322                          * Add one more byte for valid surrogate pairs. Invalid
 323                          * surrogates will be replaced with 0xfffd and take up
 324                          * only 3 bytes.
 325                          */
 326                         if ((c & 0xfc00) == 0xd800) {
 327                                 /*
 328                                  * If the very last word is a high surrogate,
 329                                  * we must ignore it since we can't access the
 330                                  * low surrogate.
 331                                  */
 332                                 if (!options_chars) {
 333                                         options_bytes -= 3;
 334                                 } else if ((*s2 & 0xfc00) == 0xdc00) {
 335                                         options_bytes++;
 336                                         options_chars--;
 337                                         s2++;
 338                                 }
 339                         }
 340                 }
 341                 if (options_bytes >= COMMAND_LINE_SIZE) {
 342                         options_bytes = safe_options_bytes;
 343                         efi_err("Command line is too long: truncated to %d bytes\n",
 344                                 options_bytes);
 345                 }
 346         }
 347
 348         options_bytes++;        /* NUL termination */
 349
 350         status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, options_bytes,
 351                              (void **)&cmdline_addr);
 352         if (status != EFI_SUCCESS)
 353                 return NULL;
 354
 355         snprintf((char *)cmdline_addr, options_bytes, "%.*ls",
 356                  options_bytes - 1, options);
 357
 358         *cmd_line_len = options_bytes;
 359         return (char *)cmdline_addr;
 360 }
 361
 362 /**
 363  * efi_exit_boot_services() - Exit boot services
 364  * @handle:     handle of the exiting image
 365  * @priv:       argument to be passed to @priv_func
 366  * @priv_func:  function to process the memory map before exiting boot services
 367  *
 368  * Handle calling ExitBootServices according to the requirements set out by the
 369  * spec.  Obtains the current memory map, and returns that info after calling
 370  * ExitBootServices.  The client must specify a function to perform any
 371  * processing of the memory map data prior to ExitBootServices.  A client
 372  * specific structure may be passed to the function via priv.  The client
 373  * function may be called multiple times.
 374  *
 375  * Return:      status code
 376  */
 377 efi_status_t efi_exit_boot_services(void *handle, void *priv,
 378                                     efi_exit_boot_map_processing priv_func)
 379 {
 380         struct efi_boot_memmap *map;
 381         efi_status_t status;
 382
 383         if (efi_disable_pci_dma)
 384                 efi_pci_disable_bridge_busmaster();
 385
 386         status = efi_get_memory_map(&map, true);
 387         if (status != EFI_SUCCESS)
 388                 return status;
 389
 390         status = priv_func(map, priv);
 391         if (status != EFI_SUCCESS) {
 392                 efi_bs_call(free_pool, map);
 393                 return status;
 394         }
 395
 396         status = efi_bs_call(exit_boot_services, handle, map->map_key);
 397
 398         if (status == EFI_INVALID_PARAMETER) {
 399                 /*
 400                  * The memory map changed between efi_get_memory_map() and
 401                  * exit_boot_services().  Per the UEFI Spec v2.6, Section 6.4:
 402                  * EFI_BOOT_SERVICES.ExitBootServices we need to get the
 403                  * updated map, and try again.  The spec implies one retry
 404                  * should be sufficent, which is confirmed against the EDK2
 405                  * implementation.  Per the spec, we can only invoke
 406                  * get_memory_map() and exit_boot_services() - we cannot alloc
 407                  * so efi_get_memory_map() cannot be used, and we must reuse
 408                  * the buffer.  For all practical purposes, the headroom in the
 409                  * buffer should account for any changes in the map so the call
 410                  * to get_memory_map() is expected to succeed here.
 411                  */
 412                 map->map_size = map->buff_size;
 413                 status = efi_bs_call(get_memory_map,
 414                                      &map->map_size,
 415                                      &map->map,
 416                                      &map->map_key,
 417                                      &map->desc_size,
 418                                      &map->desc_ver);
 419
 420                 /* exit_boot_services() was called, thus cannot free */
 421                 if (status != EFI_SUCCESS)
 422                         return status;
 423
 424                 status = priv_func(map, priv);
 425                 /* exit_boot_services() was called, thus cannot free */
 426                 if (status != EFI_SUCCESS)
 427                         return status;
 428
 429                 status = efi_bs_call(exit_boot_services, handle, map->map_key);
 430         }
 431
 432         return status;
 433 }
 434
 435 /**
 436  * get_efi_config_table() - retrieve UEFI configuration table
 437  * @guid:       GUID of the configuration table to be retrieved
 438  * Return:      pointer to the configuration table or NULL
 439  */
 440 void *get_efi_config_table(efi_guid_t guid)
 441 {
 442         unsigned long tables = efi_table_attr(efi_system_table, tables);
 443         int nr_tables = efi_table_attr(efi_system_table, nr_tables);
 444         int i;
 445
 446         for (i = 0; i < nr_tables; i++) {
 447                 efi_config_table_t *t = (void *)tables;
 448
 449                 if (efi_guidcmp(t->guid, guid) == 0)
 450                         return efi_table_attr(t, table);
 451
 452                 tables += efi_is_native() ? sizeof(efi_config_table_t)
 453                                           : sizeof(efi_config_table_32_t);
 454         }
 455         return NULL;
 456 }
 457
 458 /*
 459  * The LINUX_EFI_INITRD_MEDIA_GUID vendor media device path below provides a way
 460  * for the firmware or bootloader to expose the initrd data directly to the stub
 461  * via the trivial LoadFile2 protocol, which is defined in the UEFI spec, and is
 462  * very easy to implement. It is a simple Linux initrd specific conduit between
 463  * kernel and firmware, allowing us to put the EFI stub (being part of the
 464  * kernel) in charge of where and when to load the initrd, while leaving it up
 465  * to the firmware to decide whether it needs to expose its filesystem hierarchy
 466  * via EFI protocols.
 467  */
 468 static const struct {
 469         struct efi_vendor_dev_path      vendor;
 470         struct efi_generic_dev_path     end;
 471 } __packed initrd_dev_path = {
 472         {
 473                 {
 474                         EFI_DEV_MEDIA,
 475                         EFI_DEV_MEDIA_VENDOR,
 476                         sizeof(struct efi_vendor_dev_path),
 477                 },
 478                 LINUX_EFI_INITRD_MEDIA_GUID
 479         }, {
 480                 EFI_DEV_END_PATH,
 481                 EFI_DEV_END_ENTIRE,
 482                 sizeof(struct efi_generic_dev_path)
 483         }
 484 };
 485
 486 /**
 487  * efi_load_initrd_dev_path() - load the initrd from the Linux initrd device path
 488  * @initrd:     pointer of struct to store the address where the initrd was loaded
 489  *              and the size of the loaded initrd
 490  * @max:        upper limit for the initrd memory allocation
 491  *
 492  * Return:
 493  * * %EFI_SUCCESS if the initrd was loaded successfully, in which
 494  *   case @load_addr and @load_size are assigned accordingly
 495  * * %EFI_NOT_FOUND if no LoadFile2 protocol exists on the initrd device path
 496  * * %EFI_OUT_OF_RESOURCES if memory allocation failed
 497  * * %EFI_LOAD_ERROR in all other cases
 498  */
 499 static
 500 efi_status_t efi_load_initrd_dev_path(struct linux_efi_initrd *initrd,
 501                                       unsigned long max)
 502 {
 503         efi_guid_t lf2_proto_guid = EFI_LOAD_FILE2_PROTOCOL_GUID;
 504         efi_device_path_protocol_t *dp;
 505         efi_load_file2_protocol_t *lf2;
 506         efi_handle_t handle;
 507         efi_status_t status;
 508
 509         dp = (efi_device_path_protocol_t *)&initrd_dev_path;
 510         status = efi_bs_call(locate_device_path, &lf2_proto_guid, &dp, &handle);
 511         if (status != EFI_SUCCESS)
 512                 return status;
 513
 514         status = efi_bs_call(handle_protocol, handle, &lf2_proto_guid,
 515                              (void **)&lf2);
 516         if (status != EFI_SUCCESS)
 517                 return status;
 518
 519         initrd->size = 0;
 520         status = efi_call_proto(lf2, load_file, dp, false, &initrd->size, NULL);
 521         if (status != EFI_BUFFER_TOO_SMALL)
 522                 return EFI_LOAD_ERROR;
 523
 524         status = efi_allocate_pages(initrd->size, &initrd->base, max);
 525         if (status != EFI_SUCCESS)
 526                 return status;
 527
 528         status = efi_call_proto(lf2, load_file, dp, false, &initrd->size,
 529                                 (void *)initrd->base);
 530         if (status != EFI_SUCCESS) {
 531                 efi_free(initrd->size, initrd->base);
 532                 return EFI_LOAD_ERROR;
 533         }
 534         return EFI_SUCCESS;
 535 }
 536
 537 static
 538 efi_status_t efi_load_initrd_cmdline(efi_loaded_image_t *image,
 539                                      struct linux_efi_initrd *initrd,
 540                                      unsigned long soft_limit,
 541                                      unsigned long hard_limit)
 542 {
 543         if (image == NULL)
 544                 return EFI_UNSUPPORTED;
 545
 546         return handle_cmdline_files(image, L"initrd=", sizeof(L"initrd=") - 2,
 547                                     soft_limit, hard_limit,
 548                                     &initrd->base, &initrd->size);
 549 }
 550
 551 /**
 552  * efi_load_initrd() - Load initial RAM disk
 553  * @image:      EFI loaded image protocol
 554  * @soft_limit: preferred address for loading the initrd
 555  * @hard_limit: upper limit address for loading the initrd
 556  *
 557  * Return:      status code
 558  */
 559 efi_status_t efi_load_initrd(efi_loaded_image_t *image,
 560                              unsigned long soft_limit,
 561                              unsigned long hard_limit,
 562                              const struct linux_efi_initrd **out)
 563 {
 564         efi_guid_t tbl_guid = LINUX_EFI_INITRD_MEDIA_GUID;
 565         efi_status_t status = EFI_SUCCESS;
 566         struct linux_efi_initrd initrd, *tbl;
 567
 568         if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD) || efi_noinitrd)
 569                 return EFI_SUCCESS;
 570
 571         status = efi_load_initrd_dev_path(&initrd, hard_limit);
 572         if (status == EFI_SUCCESS) {
 573                 efi_info("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n");
 574                 if (initrd.size > 0 &&
 575                     efi_measure_tagged_event(initrd.base, initrd.size,
 576                                              EFISTUB_EVT_INITRD) == EFI_SUCCESS)
 577                         efi_info("Measured initrd data into PCR 9\n");
 578         } else if (status == EFI_NOT_FOUND) {
 579                 status = efi_load_initrd_cmdline(image, &initrd, soft_limit,
 580                                                  hard_limit);
 581                 /* command line loader disabled or no initrd= passed? */
 582                 if (status == EFI_UNSUPPORTED || status == EFI_NOT_READY)
 583                         return EFI_SUCCESS;
 584                 if (status == EFI_SUCCESS)
 585                         efi_info("Loaded initrd from command line option\n");
 586         }
 587         if (status != EFI_SUCCESS)
 588                 goto failed;
 589
 590         status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(initrd),
 591                              (void **)&tbl);
 592         if (status != EFI_SUCCESS)
 593                 goto free_initrd;
 594
 595         *tbl = initrd;
 596         status = efi_bs_call(install_configuration_table, &tbl_guid, tbl);
 597         if (status != EFI_SUCCESS)
 598                 goto free_tbl;
 599
 600         if (out)
 601                 *out = tbl;
 602         return EFI_SUCCESS;
 603
 604 free_tbl:
 605         efi_bs_call(free_pool, tbl);
 606 free_initrd:
 607         efi_free(initrd.size, initrd.base);
 608 failed:
 609         efi_err("Failed to load initrd: 0x%lx\n", status);
 610         return status;
 611 }
 612
 613 /**
 614  * efi_wait_for_key() - Wait for key stroke
 615  * @usec:       number of microseconds to wait for key stroke
 616  * @key:        key entered
 617  *
 618  * Wait for up to @usec microseconds for a key stroke.
 619  *
 620  * Return:      status code, EFI_SUCCESS if key received
 621  */
 622 efi_status_t efi_wait_for_key(unsigned long usec, efi_input_key_t *key)
 623 {
 624         efi_event_t events[2], timer;
 625         unsigned long index;
 626         efi_simple_text_input_protocol_t *con_in;
 627         efi_status_t status;
 628
 629         con_in = efi_table_attr(efi_system_table, con_in);
 630         if (!con_in)
 631                 return EFI_UNSUPPORTED;
 632         efi_set_event_at(events, 0, efi_table_attr(con_in, wait_for_key));
 633
 634         status = efi_bs_call(create_event, EFI_EVT_TIMER, 0, NULL, NULL, &timer);
 635         if (status != EFI_SUCCESS)
 636                 return status;
 637
 638         status = efi_bs_call(set_timer, timer, EfiTimerRelative,
 639                              EFI_100NSEC_PER_USEC * usec);
 640         if (status != EFI_SUCCESS)
 641                 return status;
 642         efi_set_event_at(events, 1, timer);
 643
 644         status = efi_bs_call(wait_for_event, 2, events, &index);
 645         if (status == EFI_SUCCESS) {
 646                 if (index == 0)
 647                         status = efi_call_proto(con_in, read_keystroke, key);
 648                 else
 649                         status = EFI_TIMEOUT;
 650         }
 651
 652         efi_bs_call(close_event, timer);
 653
 654         return status;
 655 }
 656
 657 /**
 658  * efi_remap_image - Remap a loaded image with the appropriate permissions
 659  *                   for code and data
 660  *
 661  * @image_base: the base of the image in memory
 662  * @alloc_size: the size of the area in memory occupied by the image
 663  * @code_size:  the size of the leading part of the image containing code
 664  *              and read-only data
 665  *
 666  * efi_remap_image() uses the EFI memory attribute protocol to remap the code
 667  * region of the loaded image read-only/executable, and the remainder
 668  * read-write/non-executable. The code region is assumed to start at the base
 669  * of the image, and will therefore cover the PE/COFF header as well.
 670  */
 671 void efi_remap_image(unsigned long image_base, unsigned alloc_size,
 672                      unsigned long code_size)
 673 {
 674         efi_guid_t guid = EFI_MEMORY_ATTRIBUTE_PROTOCOL_GUID;
 675         efi_memory_attribute_protocol_t *memattr;
 676         efi_status_t status;
 677         u64 attr;
 678
 679         /*
 680          * If the firmware implements the EFI_MEMORY_ATTRIBUTE_PROTOCOL, let's
 681          * invoke it to remap the text/rodata region of the decompressed image
 682          * as read-only and the data/bss region as non-executable.
 683          */
 684         status = efi_bs_call(locate_protocol, &guid, NULL, (void **)&memattr);
 685         if (status != EFI_SUCCESS)
 686                 return;
 687
 688         // Get the current attributes for the entire region
 689         status = memattr->get_memory_attributes(memattr, image_base,
 690                                                 alloc_size, &attr);
 691         if (status != EFI_SUCCESS) {
 692                 efi_warn("Failed to retrieve memory attributes for image region: 0x%lx\n",
 693                          status);
 694                 return;
 695         }
 696
 697         // Mark the code region as read-only
 698         status = memattr->set_memory_attributes(memattr, image_base, code_size,
 699                                                 EFI_MEMORY_RO);
 700         if (status != EFI_SUCCESS) {
 701                 efi_warn("Failed to remap code region read-only\n");
 702                 return;
 703         }
 704
 705         // If the entire region was already mapped as non-exec, clear the
 706         // attribute from the code region. Otherwise, set it on the data
 707         // region.
 708         if (attr & EFI_MEMORY_XP) {
 709                 status = memattr->clear_memory_attributes(memattr, image_base,
 710                                                           code_size,
 711                                                           EFI_MEMORY_XP);
 712                 if (status != EFI_SUCCESS)
 713                         efi_warn("Failed to remap code region executable\n");
 714         } else {
 715                 status = memattr->set_memory_attributes(memattr,
 716                                                         image_base + code_size,
 717                                                         alloc_size - code_size,
 718                                                         EFI_MEMORY_XP);
 719                 if (status != EFI_SUCCESS)
 720                         efi_warn("Failed to remap data region non-executable\n");
 721         }
 722 }