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1// SPDX-License-Identifier: GPL-2.02/*3 * Helper functions used by the EFI stub on multiple4 * architectures. This should be #included by the EFI stub5 * implementation files.6 *7 * Copyright 2011 Intel Corporation; author Matt Fleming8 */9 10#include <linux/stdarg.h>11 12#include <linux/efi.h>13#include <linux/kernel.h>14#include <linux/overflow.h>15#include <asm/efi.h>16#include <asm/setup.h>17 18#include "efistub.h"19 20bool efi_nochunk;21bool efi_nokaslr = !IS_ENABLED(CONFIG_RANDOMIZE_BASE);22bool efi_novamap;23 24static bool efi_noinitrd;25static bool efi_nosoftreserve;26static bool efi_disable_pci_dma = IS_ENABLED(CONFIG_EFI_DISABLE_PCI_DMA);27 28int efi_mem_encrypt;29 30bool __pure __efi_soft_reserve_enabled(void)31{32 return !efi_nosoftreserve;33}34 35/**36 * efi_parse_options() - Parse EFI command line options37 * @cmdline: kernel command line38 *39 * Parse the ASCII string @cmdline for EFI options, denoted by the efi=40 * option, e.g. efi=nochunk.41 *42 * It should be noted that efi= is parsed in two very different43 * environments, first in the early boot environment of the EFI boot44 * stub, and subsequently during the kernel boot.45 *46 * Return: status code47 */48efi_status_t efi_parse_options(char const *cmdline)49{50 size_t len;51 efi_status_t status;52 char *str, *buf;53 54 if (!cmdline)55 return EFI_SUCCESS;56 57 len = strnlen(cmdline, COMMAND_LINE_SIZE - 1) + 1;58 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, len, (void **)&buf);59 if (status != EFI_SUCCESS)60 return status;61 62 memcpy(buf, cmdline, len - 1);63 buf[len - 1] = '\0';64 str = skip_spaces(buf);65 66 while (*str) {67 char *param, *val;68 69 str = next_arg(str, ¶m, &val);70 if (!val && !strcmp(param, "--"))71 break;72 73 if (!strcmp(param, "nokaslr")) {74 efi_nokaslr = true;75 } else if (!strcmp(param, "quiet")) {76 efi_loglevel = CONSOLE_LOGLEVEL_QUIET;77 } else if (!strcmp(param, "noinitrd")) {78 efi_noinitrd = true;79 } else if (IS_ENABLED(CONFIG_X86_64) && !strcmp(param, "no5lvl")) {80 efi_no5lvl = true;81 } else if (IS_ENABLED(CONFIG_ARCH_HAS_MEM_ENCRYPT) &&82 !strcmp(param, "mem_encrypt") && val) {83 if (parse_option_str(val, "on"))84 efi_mem_encrypt = 1;85 else if (parse_option_str(val, "off"))86 efi_mem_encrypt = -1;87 } else if (!strcmp(param, "efi") && val) {88 efi_nochunk = parse_option_str(val, "nochunk");89 efi_novamap |= parse_option_str(val, "novamap");90 91 efi_nosoftreserve = IS_ENABLED(CONFIG_EFI_SOFT_RESERVE) &&92 parse_option_str(val, "nosoftreserve");93 94 if (parse_option_str(val, "disable_early_pci_dma"))95 efi_disable_pci_dma = true;96 if (parse_option_str(val, "no_disable_early_pci_dma"))97 efi_disable_pci_dma = false;98 if (parse_option_str(val, "debug"))99 efi_loglevel = CONSOLE_LOGLEVEL_DEBUG;100 } else if (!strcmp(param, "video") &&101 val && strstarts(val, "efifb:")) {102 efi_parse_option_graphics(val + strlen("efifb:"));103 }104 }105 efi_bs_call(free_pool, buf);106 return EFI_SUCCESS;107}108 109/*110 * The EFI_LOAD_OPTION descriptor has the following layout:111 * u32 Attributes;112 * u16 FilePathListLength;113 * u16 Description[];114 * efi_device_path_protocol_t FilePathList[];115 * u8 OptionalData[];116 *117 * This function validates and unpacks the variable-size data fields.118 */119static120bool efi_load_option_unpack(efi_load_option_unpacked_t *dest,121 const efi_load_option_t *src, size_t size)122{123 const void *pos;124 u16 c;125 efi_device_path_protocol_t header;126 const efi_char16_t *description;127 const efi_device_path_protocol_t *file_path_list;128 129 if (size < offsetof(efi_load_option_t, variable_data))130 return false;131 pos = src->variable_data;132 size -= offsetof(efi_load_option_t, variable_data);133 134 if ((src->attributes & ~EFI_LOAD_OPTION_MASK) != 0)135 return false;136 137 /* Scan description. */138 description = pos;139 do {140 if (size < sizeof(c))141 return false;142 c = *(const u16 *)pos;143 pos += sizeof(c);144 size -= sizeof(c);145 } while (c != L'\0');146 147 /* Scan file_path_list. */148 file_path_list = pos;149 do {150 if (size < sizeof(header))151 return false;152 header = *(const efi_device_path_protocol_t *)pos;153 if (header.length < sizeof(header))154 return false;155 if (size < header.length)156 return false;157 pos += header.length;158 size -= header.length;159 } while ((header.type != EFI_DEV_END_PATH && header.type != EFI_DEV_END_PATH2) ||160 (header.sub_type != EFI_DEV_END_ENTIRE));161 if (pos != (const void *)file_path_list + src->file_path_list_length)162 return false;163 164 dest->attributes = src->attributes;165 dest->file_path_list_length = src->file_path_list_length;166 dest->description = description;167 dest->file_path_list = file_path_list;168 dest->optional_data_size = size;169 dest->optional_data = size ? pos : NULL;170 171 return true;172}173 174/*175 * At least some versions of Dell firmware pass the entire contents of the176 * Boot#### variable, i.e. the EFI_LOAD_OPTION descriptor, rather than just the177 * OptionalData field.178 *179 * Detect this case and extract OptionalData.180 */181void efi_apply_loadoptions_quirk(const void **load_options, u32 *load_options_size)182{183 const efi_load_option_t *load_option = *load_options;184 efi_load_option_unpacked_t load_option_unpacked;185 186 if (!IS_ENABLED(CONFIG_X86))187 return;188 if (!load_option)189 return;190 if (*load_options_size < sizeof(*load_option))191 return;192 if ((load_option->attributes & ~EFI_LOAD_OPTION_BOOT_MASK) != 0)193 return;194 195 if (!efi_load_option_unpack(&load_option_unpacked, load_option, *load_options_size))196 return;197 198 efi_warn_once(FW_BUG "LoadOptions is an EFI_LOAD_OPTION descriptor\n");199 efi_warn_once(FW_BUG "Using OptionalData as a workaround\n");200 201 *load_options = load_option_unpacked.optional_data;202 *load_options_size = load_option_unpacked.optional_data_size;203}204 205enum efistub_event_type {206 EFISTUB_EVT_INITRD,207 EFISTUB_EVT_LOAD_OPTIONS,208 EFISTUB_EVT_COUNT,209};210 211#define STR_WITH_SIZE(s) sizeof(s), s212 213static const struct {214 u32 pcr_index;215 u32 event_id;216 u32 event_data_len;217 u8 event_data[52];218} events[] = {219 [EFISTUB_EVT_INITRD] = {220 9,221 INITRD_EVENT_TAG_ID,222 STR_WITH_SIZE("Linux initrd")223 },224 [EFISTUB_EVT_LOAD_OPTIONS] = {225 9,226 LOAD_OPTIONS_EVENT_TAG_ID,227 STR_WITH_SIZE("LOADED_IMAGE::LoadOptions")228 },229};230 231static_assert(sizeof(efi_tcg2_event_t) == sizeof(efi_cc_event_t));232 233union efistub_event {234 efi_tcg2_event_t tcg2_data;235 efi_cc_event_t cc_data;236};237 238struct efistub_measured_event {239 union efistub_event event_data;240 TCG_PCClientTaggedEvent tagged_event __packed;241};242 243static efi_status_t efi_measure_tagged_event(unsigned long load_addr,244 unsigned long load_size,245 enum efistub_event_type event)246{247 union {248 efi_status_t249 (__efiapi *hash_log_extend_event)(void *, u64, efi_physical_addr_t,250 u64, const union efistub_event *);251 struct { u32 hash_log_extend_event; } mixed_mode;252 } method;253 struct efistub_measured_event *evt;254 int size = struct_size(evt, tagged_event.tagged_event_data,255 events[event].event_data_len);256 efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID;257 efi_tcg2_protocol_t *tcg2 = NULL;258 union efistub_event ev;259 efi_status_t status;260 void *protocol;261 262 efi_bs_call(locate_protocol, &tcg2_guid, NULL, (void **)&tcg2);263 if (tcg2) {264 ev.tcg2_data = (struct efi_tcg2_event){265 .event_size = size,266 .event_header.header_size = sizeof(ev.tcg2_data.event_header),267 .event_header.header_version = EFI_TCG2_EVENT_HEADER_VERSION,268 .event_header.pcr_index = events[event].pcr_index,269 .event_header.event_type = EV_EVENT_TAG,270 };271 protocol = tcg2;272 method.hash_log_extend_event =273 (void *)efi_table_attr(tcg2, hash_log_extend_event);274 } else {275 efi_guid_t cc_guid = EFI_CC_MEASUREMENT_PROTOCOL_GUID;276 efi_cc_protocol_t *cc = NULL;277 278 efi_bs_call(locate_protocol, &cc_guid, NULL, (void **)&cc);279 if (!cc)280 return EFI_UNSUPPORTED;281 282 ev.cc_data = (struct efi_cc_event){283 .event_size = size,284 .event_header.header_size = sizeof(ev.cc_data.event_header),285 .event_header.header_version = EFI_CC_EVENT_HEADER_VERSION,286 .event_header.event_type = EV_EVENT_TAG,287 };288 289 status = efi_call_proto(cc, map_pcr_to_mr_index,290 events[event].pcr_index,291 &ev.cc_data.event_header.mr_index);292 if (status != EFI_SUCCESS)293 goto fail;294 295 protocol = cc;296 method.hash_log_extend_event =297 (void *)efi_table_attr(cc, hash_log_extend_event);298 }299 300 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size, (void **)&evt);301 if (status != EFI_SUCCESS)302 goto fail;303 304 *evt = (struct efistub_measured_event) {305 .event_data = ev,306 .tagged_event.tagged_event_id = events[event].event_id,307 .tagged_event.tagged_event_data_size = events[event].event_data_len,308 };309 310 memcpy(evt->tagged_event.tagged_event_data, events[event].event_data,311 events[event].event_data_len);312 313 status = efi_fn_call(&method, hash_log_extend_event, protocol, 0,314 load_addr, load_size, &evt->event_data);315 efi_bs_call(free_pool, evt);316 317 if (status == EFI_SUCCESS)318 return EFI_SUCCESS;319 320fail:321 efi_warn("Failed to measure data for event %d: 0x%lx\n", event, status);322 return status;323}324 325/*326 * Convert the unicode UEFI command line to ASCII to pass to kernel.327 * Size of memory allocated return in *cmd_line_len.328 * Returns NULL on error.329 */330char *efi_convert_cmdline(efi_loaded_image_t *image, int *cmd_line_len)331{332 const efi_char16_t *options = efi_table_attr(image, load_options);333 u32 options_size = efi_table_attr(image, load_options_size);334 int options_bytes = 0, safe_options_bytes = 0; /* UTF-8 bytes */335 unsigned long cmdline_addr = 0;336 const efi_char16_t *s2;337 bool in_quote = false;338 efi_status_t status;339 u32 options_chars;340 341 if (options_size > 0)342 efi_measure_tagged_event((unsigned long)options, options_size,343 EFISTUB_EVT_LOAD_OPTIONS);344 345 efi_apply_loadoptions_quirk((const void **)&options, &options_size);346 options_chars = options_size / sizeof(efi_char16_t);347 348 if (options) {349 s2 = options;350 while (options_bytes < COMMAND_LINE_SIZE && options_chars--) {351 efi_char16_t c = *s2++;352 353 if (c < 0x80) {354 if (c == L'\0' || c == L'\n')355 break;356 if (c == L'"')357 in_quote = !in_quote;358 else if (!in_quote && isspace((char)c))359 safe_options_bytes = options_bytes;360 361 options_bytes++;362 continue;363 }364 365 /*366 * Get the number of UTF-8 bytes corresponding to a367 * UTF-16 character.368 * The first part handles everything in the BMP.369 */370 options_bytes += 2 + (c >= 0x800);371 /*372 * Add one more byte for valid surrogate pairs. Invalid373 * surrogates will be replaced with 0xfffd and take up374 * only 3 bytes.375 */376 if ((c & 0xfc00) == 0xd800) {377 /*378 * If the very last word is a high surrogate,379 * we must ignore it since we can't access the380 * low surrogate.381 */382 if (!options_chars) {383 options_bytes -= 3;384 } else if ((*s2 & 0xfc00) == 0xdc00) {385 options_bytes++;386 options_chars--;387 s2++;388 }389 }390 }391 if (options_bytes >= COMMAND_LINE_SIZE) {392 options_bytes = safe_options_bytes;393 efi_err("Command line is too long: truncated to %d bytes\n",394 options_bytes);395 }396 }397 398 options_bytes++; /* NUL termination */399 400 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, options_bytes,401 (void **)&cmdline_addr);402 if (status != EFI_SUCCESS)403 return NULL;404 405 snprintf((char *)cmdline_addr, options_bytes, "%.*ls",406 options_bytes - 1, options);407 408 *cmd_line_len = options_bytes;409 return (char *)cmdline_addr;410}411 412/**413 * efi_exit_boot_services() - Exit boot services414 * @handle: handle of the exiting image415 * @priv: argument to be passed to @priv_func416 * @priv_func: function to process the memory map before exiting boot services417 *418 * Handle calling ExitBootServices according to the requirements set out by the419 * spec. Obtains the current memory map, and returns that info after calling420 * ExitBootServices. The client must specify a function to perform any421 * processing of the memory map data prior to ExitBootServices. A client422 * specific structure may be passed to the function via priv. The client423 * function may be called multiple times.424 *425 * Return: status code426 */427efi_status_t efi_exit_boot_services(void *handle, void *priv,428 efi_exit_boot_map_processing priv_func)429{430 struct efi_boot_memmap *map;431 efi_status_t status;432 433 if (efi_disable_pci_dma)434 efi_pci_disable_bridge_busmaster();435 436 status = efi_get_memory_map(&map, true);437 if (status != EFI_SUCCESS)438 return status;439 440 status = priv_func(map, priv);441 if (status != EFI_SUCCESS) {442 efi_bs_call(free_pool, map);443 return status;444 }445 446 status = efi_bs_call(exit_boot_services, handle, map->map_key);447 448 if (status == EFI_INVALID_PARAMETER) {449 /*450 * The memory map changed between efi_get_memory_map() and451 * exit_boot_services(). Per the UEFI Spec v2.6, Section 6.4:452 * EFI_BOOT_SERVICES.ExitBootServices we need to get the453 * updated map, and try again. The spec implies one retry454 * should be sufficent, which is confirmed against the EDK2455 * implementation. Per the spec, we can only invoke456 * get_memory_map() and exit_boot_services() - we cannot alloc457 * so efi_get_memory_map() cannot be used, and we must reuse458 * the buffer. For all practical purposes, the headroom in the459 * buffer should account for any changes in the map so the call460 * to get_memory_map() is expected to succeed here.461 */462 map->map_size = map->buff_size;463 status = efi_bs_call(get_memory_map,464 &map->map_size,465 &map->map,466 &map->map_key,467 &map->desc_size,468 &map->desc_ver);469 470 /* exit_boot_services() was called, thus cannot free */471 if (status != EFI_SUCCESS)472 return status;473 474 status = priv_func(map, priv);475 /* exit_boot_services() was called, thus cannot free */476 if (status != EFI_SUCCESS)477 return status;478 479 status = efi_bs_call(exit_boot_services, handle, map->map_key);480 }481 482 return status;483}484 485/**486 * get_efi_config_table() - retrieve UEFI configuration table487 * @guid: GUID of the configuration table to be retrieved488 * Return: pointer to the configuration table or NULL489 */490void *get_efi_config_table(efi_guid_t guid)491{492 unsigned long tables = efi_table_attr(efi_system_table, tables);493 int nr_tables = efi_table_attr(efi_system_table, nr_tables);494 int i;495 496 for (i = 0; i < nr_tables; i++) {497 efi_config_table_t *t = (void *)tables;498 499 if (efi_guidcmp(t->guid, guid) == 0)500 return efi_table_attr(t, table);501 502 tables += efi_is_native() ? sizeof(efi_config_table_t)503 : sizeof(efi_config_table_32_t);504 }505 return NULL;506}507 508/*509 * The LINUX_EFI_INITRD_MEDIA_GUID vendor media device path below provides a way510 * for the firmware or bootloader to expose the initrd data directly to the stub511 * via the trivial LoadFile2 protocol, which is defined in the UEFI spec, and is512 * very easy to implement. It is a simple Linux initrd specific conduit between513 * kernel and firmware, allowing us to put the EFI stub (being part of the514 * kernel) in charge of where and when to load the initrd, while leaving it up515 * to the firmware to decide whether it needs to expose its filesystem hierarchy516 * via EFI protocols.517 */518static const struct {519 struct efi_vendor_dev_path vendor;520 struct efi_generic_dev_path end;521} __packed initrd_dev_path = {522 {523 {524 EFI_DEV_MEDIA,525 EFI_DEV_MEDIA_VENDOR,526 sizeof(struct efi_vendor_dev_path),527 },528 LINUX_EFI_INITRD_MEDIA_GUID529 }, {530 EFI_DEV_END_PATH,531 EFI_DEV_END_ENTIRE,532 sizeof(struct efi_generic_dev_path)533 }534};535 536/**537 * efi_load_initrd_dev_path() - load the initrd from the Linux initrd device path538 * @initrd: pointer of struct to store the address where the initrd was loaded539 * and the size of the loaded initrd540 * @max: upper limit for the initrd memory allocation541 *542 * Return:543 * * %EFI_SUCCESS if the initrd was loaded successfully, in which544 * case @load_addr and @load_size are assigned accordingly545 * * %EFI_NOT_FOUND if no LoadFile2 protocol exists on the initrd device path546 * * %EFI_OUT_OF_RESOURCES if memory allocation failed547 * * %EFI_LOAD_ERROR in all other cases548 */549static550efi_status_t efi_load_initrd_dev_path(struct linux_efi_initrd *initrd,551 unsigned long max)552{553 efi_guid_t lf2_proto_guid = EFI_LOAD_FILE2_PROTOCOL_GUID;554 efi_device_path_protocol_t *dp;555 efi_load_file2_protocol_t *lf2;556 efi_handle_t handle;557 efi_status_t status;558 559 dp = (efi_device_path_protocol_t *)&initrd_dev_path;560 status = efi_bs_call(locate_device_path, &lf2_proto_guid, &dp, &handle);561 if (status != EFI_SUCCESS)562 return status;563 564 status = efi_bs_call(handle_protocol, handle, &lf2_proto_guid,565 (void **)&lf2);566 if (status != EFI_SUCCESS)567 return status;568 569 initrd->size = 0;570 status = efi_call_proto(lf2, load_file, dp, false, &initrd->size, NULL);571 if (status != EFI_BUFFER_TOO_SMALL)572 return EFI_LOAD_ERROR;573 574 status = efi_allocate_pages(initrd->size, &initrd->base, max);575 if (status != EFI_SUCCESS)576 return status;577 578 status = efi_call_proto(lf2, load_file, dp, false, &initrd->size,579 (void *)initrd->base);580 if (status != EFI_SUCCESS) {581 efi_free(initrd->size, initrd->base);582 return EFI_LOAD_ERROR;583 }584 return EFI_SUCCESS;585}586 587static588efi_status_t efi_load_initrd_cmdline(efi_loaded_image_t *image,589 struct linux_efi_initrd *initrd,590 unsigned long soft_limit,591 unsigned long hard_limit)592{593 if (image == NULL)594 return EFI_UNSUPPORTED;595 596 return handle_cmdline_files(image, L"initrd=", sizeof(L"initrd=") - 2,597 soft_limit, hard_limit,598 &initrd->base, &initrd->size);599}600 601/**602 * efi_load_initrd() - Load initial RAM disk603 * @image: EFI loaded image protocol604 * @soft_limit: preferred address for loading the initrd605 * @hard_limit: upper limit address for loading the initrd606 *607 * Return: status code608 */609efi_status_t efi_load_initrd(efi_loaded_image_t *image,610 unsigned long soft_limit,611 unsigned long hard_limit,612 const struct linux_efi_initrd **out)613{614 efi_guid_t tbl_guid = LINUX_EFI_INITRD_MEDIA_GUID;615 efi_status_t status = EFI_SUCCESS;616 struct linux_efi_initrd initrd, *tbl;617 618 if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD) || efi_noinitrd)619 return EFI_SUCCESS;620 621 status = efi_load_initrd_dev_path(&initrd, hard_limit);622 if (status == EFI_SUCCESS) {623 efi_info("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n");624 if (initrd.size > 0 &&625 efi_measure_tagged_event(initrd.base, initrd.size,626 EFISTUB_EVT_INITRD) == EFI_SUCCESS)627 efi_info("Measured initrd data into PCR 9\n");628 } else if (status == EFI_NOT_FOUND) {629 status = efi_load_initrd_cmdline(image, &initrd, soft_limit,630 hard_limit);631 /* command line loader disabled or no initrd= passed? */632 if (status == EFI_UNSUPPORTED || status == EFI_NOT_READY)633 return EFI_SUCCESS;634 if (status == EFI_SUCCESS)635 efi_info("Loaded initrd from command line option\n");636 }637 if (status != EFI_SUCCESS)638 goto failed;639 640 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(initrd),641 (void **)&tbl);642 if (status != EFI_SUCCESS)643 goto free_initrd;644 645 *tbl = initrd;646 status = efi_bs_call(install_configuration_table, &tbl_guid, tbl);647 if (status != EFI_SUCCESS)648 goto free_tbl;649 650 if (out)651 *out = tbl;652 return EFI_SUCCESS;653 654free_tbl:655 efi_bs_call(free_pool, tbl);656free_initrd:657 efi_free(initrd.size, initrd.base);658failed:659 efi_err("Failed to load initrd: 0x%lx\n", status);660 return status;661}662 663/**664 * efi_wait_for_key() - Wait for key stroke665 * @usec: number of microseconds to wait for key stroke666 * @key: key entered667 *668 * Wait for up to @usec microseconds for a key stroke.669 *670 * Return: status code, EFI_SUCCESS if key received671 */672efi_status_t efi_wait_for_key(unsigned long usec, efi_input_key_t *key)673{674 efi_event_t events[2], timer;675 unsigned long index;676 efi_simple_text_input_protocol_t *con_in;677 efi_status_t status;678 679 con_in = efi_table_attr(efi_system_table, con_in);680 if (!con_in)681 return EFI_UNSUPPORTED;682 efi_set_event_at(events, 0, efi_table_attr(con_in, wait_for_key));683 684 status = efi_bs_call(create_event, EFI_EVT_TIMER, 0, NULL, NULL, &timer);685 if (status != EFI_SUCCESS)686 return status;687 688 status = efi_bs_call(set_timer, timer, EfiTimerRelative,689 EFI_100NSEC_PER_USEC * usec);690 if (status != EFI_SUCCESS)691 return status;692 efi_set_event_at(events, 1, timer);693 694 status = efi_bs_call(wait_for_event, 2, events, &index);695 if (status == EFI_SUCCESS) {696 if (index == 0)697 status = efi_call_proto(con_in, read_keystroke, key);698 else699 status = EFI_TIMEOUT;700 }701 702 efi_bs_call(close_event, timer);703 704 return status;705}706 707/**708 * efi_remap_image - Remap a loaded image with the appropriate permissions709 * for code and data710 *711 * @image_base: the base of the image in memory712 * @alloc_size: the size of the area in memory occupied by the image713 * @code_size: the size of the leading part of the image containing code714 * and read-only data715 *716 * efi_remap_image() uses the EFI memory attribute protocol to remap the code717 * region of the loaded image read-only/executable, and the remainder718 * read-write/non-executable. The code region is assumed to start at the base719 * of the image, and will therefore cover the PE/COFF header as well.720 */721void efi_remap_image(unsigned long image_base, unsigned alloc_size,722 unsigned long code_size)723{724 efi_guid_t guid = EFI_MEMORY_ATTRIBUTE_PROTOCOL_GUID;725 efi_memory_attribute_protocol_t *memattr;726 efi_status_t status;727 u64 attr;728 729 /*730 * If the firmware implements the EFI_MEMORY_ATTRIBUTE_PROTOCOL, let's731 * invoke it to remap the text/rodata region of the decompressed image732 * as read-only and the data/bss region as non-executable.733 */734 status = efi_bs_call(locate_protocol, &guid, NULL, (void **)&memattr);735 if (status != EFI_SUCCESS)736 return;737 738 // Get the current attributes for the entire region739 status = memattr->get_memory_attributes(memattr, image_base,740 alloc_size, &attr);741 if (status != EFI_SUCCESS) {742 efi_warn("Failed to retrieve memory attributes for image region: 0x%lx\n",743 status);744 return;745 }746 747 // Mark the code region as read-only748 status = memattr->set_memory_attributes(memattr, image_base, code_size,749 EFI_MEMORY_RO);750 if (status != EFI_SUCCESS) {751 efi_warn("Failed to remap code region read-only\n");752 return;753 }754 755 // If the entire region was already mapped as non-exec, clear the756 // attribute from the code region. Otherwise, set it on the data757 // region.758 if (attr & EFI_MEMORY_XP) {759 status = memattr->clear_memory_attributes(memattr, image_base,760 code_size,761 EFI_MEMORY_XP);762 if (status != EFI_SUCCESS)763 efi_warn("Failed to remap code region executable\n");764 } else {765 status = memattr->set_memory_attributes(memattr,766 image_base + code_size,767 alloc_size - code_size,768 EFI_MEMORY_XP);769 if (status != EFI_SUCCESS)770 efi_warn("Failed to remap data region non-executable\n");771 }772}773