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 <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 options
 37 * @cmdline:	kernel command line
 38 *
 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 different
 43 * environments, first in the early boot environment of the EFI boot
 44 * stub, and subsequently during the kernel boot.
 45 *
 46 * Return:	status code
 47 */
 48efi_status_t efi_parse_options(char const *cmdline)
 49{
 50	char *buf __free(efi_pool) = NULL;
 51	efi_status_t status;
 52	size_t len;
 53	char *str;
 54
 55	if (!cmdline)
 56		return EFI_SUCCESS;
 57
 58	len = strnlen(cmdline, COMMAND_LINE_SIZE - 1) + 1;
 59	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, len, (void **)&buf);
 60	if (status != EFI_SUCCESS)
 61		return status;
 62
 63	memcpy(buf, cmdline, len - 1);
 64	buf[len - 1] = '\0';
 65	str = skip_spaces(buf);
 66
 67	while (*str) {
 68		char *param, *val;
 69
 70		str = next_arg(str, &param, &val);
 71		if (!val && !strcmp(param, "--"))
 72			break;
 73
 74		if (!strcmp(param, "nokaslr")) {
 75			efi_nokaslr = true;
 76		} else if (!strcmp(param, "quiet")) {
 77			efi_loglevel = CONSOLE_LOGLEVEL_QUIET;
 78		} else if (!strcmp(param, "noinitrd")) {
 79			efi_noinitrd = true;
 80		} else if (IS_ENABLED(CONFIG_X86_64) && !strcmp(param, "no5lvl")) {
 81			efi_no5lvl = true;
 82		} else if (IS_ENABLED(CONFIG_ARCH_HAS_MEM_ENCRYPT) &&
 83			   !strcmp(param, "mem_encrypt") && val) {
 84			if (parse_option_str(val, "on"))
 85				efi_mem_encrypt = 1;
 86			else if (parse_option_str(val, "off"))
 87				efi_mem_encrypt = -1;
 88		} else if (!strcmp(param, "efi") && val) {
 89			efi_nochunk = parse_option_str(val, "nochunk");
 90			efi_novamap |= parse_option_str(val, "novamap");
 91
 92			efi_nosoftreserve = IS_ENABLED(CONFIG_EFI_SOFT_RESERVE) &&
 93					    parse_option_str(val, "nosoftreserve");
 94
 95			if (parse_option_str(val, "disable_early_pci_dma"))
 96				efi_disable_pci_dma = true;
 97			if (parse_option_str(val, "no_disable_early_pci_dma"))
 98				efi_disable_pci_dma = false;
 99			if (parse_option_str(val, "debug"))
100				efi_loglevel = CONSOLE_LOGLEVEL_DEBUG;
101		} else if (!strcmp(param, "video") &&
102			   val && strstarts(val, "efifb:")) {
103			efi_parse_option_graphics(val + strlen("efifb:"));
104		}
105	}
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 */
119static
120bool 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 the
176 * Boot#### variable, i.e. the EFI_LOAD_OPTION descriptor, rather than just the
177 * 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), s
212
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_t
249		(__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 __free(efi_pool) = NULL;
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
316	if (status == EFI_SUCCESS)
317		return EFI_SUCCESS;
318
319fail:
320	efi_warn("Failed to measure data for event %d: 0x%lx\n", event, status);
321	return status;
322}
323
324/*
325 * Convert the unicode UEFI command line to ASCII to pass to kernel.
326 * Size of memory allocated return in *cmd_line_len.
327 * Returns NULL on error.
328 */
329char *efi_convert_cmdline(efi_loaded_image_t *image)
330{
331	const efi_char16_t *options = efi_table_attr(image, load_options);
332	u32 options_size = efi_table_attr(image, load_options_size);
333	int options_bytes = 0, safe_options_bytes = 0;  /* UTF-8 bytes */
334	unsigned long cmdline_addr = 0;
335	const efi_char16_t *s2;
336	bool in_quote = false;
337	efi_status_t status;
338	u32 options_chars;
339
340	if (options_size > 0)
341		efi_measure_tagged_event((unsigned long)options, options_size,
342					 EFISTUB_EVT_LOAD_OPTIONS);
343
344	efi_apply_loadoptions_quirk((const void **)&options, &options_size);
345	options_chars = options_size / sizeof(efi_char16_t);
346
347	if (options) {
348		s2 = options;
349		while (options_bytes < COMMAND_LINE_SIZE && options_chars--) {
350			efi_char16_t c = *s2++;
351
352			if (c < 0x80) {
353				if (c == L'\0' || c == L'\n')
354					break;
355				if (c == L'"')
356					in_quote = !in_quote;
357				else if (!in_quote && isspace((char)c))
358					safe_options_bytes = options_bytes;
359
360				options_bytes++;
361				continue;
362			}
363
364			/*
365			 * Get the number of UTF-8 bytes corresponding to a
366			 * UTF-16 character.
367			 * The first part handles everything in the BMP.
368			 */
369			options_bytes += 2 + (c >= 0x800);
370			/*
371			 * Add one more byte for valid surrogate pairs. Invalid
372			 * surrogates will be replaced with 0xfffd and take up
373			 * only 3 bytes.
374			 */
375			if ((c & 0xfc00) == 0xd800) {
376				/*
377				 * If the very last word is a high surrogate,
378				 * we must ignore it since we can't access the
379				 * low surrogate.
380				 */
381				if (!options_chars) {
382					options_bytes -= 3;
383				} else if ((*s2 & 0xfc00) == 0xdc00) {
384					options_bytes++;
385					options_chars--;
386					s2++;
387				}
388			}
389		}
390		if (options_bytes >= COMMAND_LINE_SIZE) {
391			options_bytes = safe_options_bytes;
392			efi_err("Command line is too long: truncated to %d bytes\n",
393				options_bytes);
394		}
395	}
396
397	options_bytes++;	/* NUL termination */
398
399	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, options_bytes,
400			     (void **)&cmdline_addr);
401	if (status != EFI_SUCCESS)
402		return NULL;
403
404	snprintf((char *)cmdline_addr, options_bytes, "%.*ls",
405		 options_bytes - 1, options);
406
407	return (char *)cmdline_addr;
408}
409
410/**
411 * efi_exit_boot_services() - Exit boot services
412 * @handle:	handle of the exiting image
413 * @priv:	argument to be passed to @priv_func
414 * @priv_func:	function to process the memory map before exiting boot services
415 *
416 * Handle calling ExitBootServices according to the requirements set out by the
417 * spec.  Obtains the current memory map, and returns that info after calling
418 * ExitBootServices.  The client must specify a function to perform any
419 * processing of the memory map data prior to ExitBootServices.  A client
420 * specific structure may be passed to the function via priv.  The client
421 * function may be called multiple times.
422 *
423 * Return:	status code
424 */
425efi_status_t efi_exit_boot_services(void *handle, void *priv,
426				    efi_exit_boot_map_processing priv_func)
427{
428	struct efi_boot_memmap *map;
429	efi_status_t status;
430
431	if (efi_disable_pci_dma)
432		efi_pci_disable_bridge_busmaster();
433
434	status = efi_get_memory_map(&map, true);
435	if (status != EFI_SUCCESS)
436		return status;
437
438	status = priv_func(map, priv);
439	if (status != EFI_SUCCESS) {
440		efi_bs_call(free_pool, map);
441		return status;
442	}
443
444	status = efi_bs_call(exit_boot_services, handle, map->map_key);
445
446	if (status == EFI_INVALID_PARAMETER) {
447		/*
448		 * The memory map changed between efi_get_memory_map() and
449		 * exit_boot_services().  Per the UEFI Spec v2.6, Section 6.4:
450		 * EFI_BOOT_SERVICES.ExitBootServices we need to get the
451		 * updated map, and try again.  The spec implies one retry
452		 * should be sufficent, which is confirmed against the EDK2
453		 * implementation.  Per the spec, we can only invoke
454		 * get_memory_map() and exit_boot_services() - we cannot alloc
455		 * so efi_get_memory_map() cannot be used, and we must reuse
456		 * the buffer.  For all practical purposes, the headroom in the
457		 * buffer should account for any changes in the map so the call
458		 * to get_memory_map() is expected to succeed here.
459		 */
460		map->map_size = map->buff_size;
461		status = efi_bs_call(get_memory_map,
462				     &map->map_size,
463				     &map->map,
464				     &map->map_key,
465				     &map->desc_size,
466				     &map->desc_ver);
467
468		/* exit_boot_services() was called, thus cannot free */
469		if (status != EFI_SUCCESS)
470			return status;
471
472		status = priv_func(map, priv);
473		/* exit_boot_services() was called, thus cannot free */
474		if (status != EFI_SUCCESS)
475			return status;
476
477		status = efi_bs_call(exit_boot_services, handle, map->map_key);
478	}
479
480	return status;
481}
482
483/**
484 * get_efi_config_table() - retrieve UEFI configuration table
485 * @guid:	GUID of the configuration table to be retrieved
486 * Return:	pointer to the configuration table or NULL
487 */
488void *get_efi_config_table(efi_guid_t guid)
489{
490	unsigned long tables = efi_table_attr(efi_system_table, tables);
491	int nr_tables = efi_table_attr(efi_system_table, nr_tables);
492	int i;
493
494	for (i = 0; i < nr_tables; i++) {
495		efi_config_table_t *t = (void *)tables;
496
497		if (efi_guidcmp(t->guid, guid) == 0)
498			return efi_table_attr(t, table);
499
500		tables += efi_is_native() ? sizeof(efi_config_table_t)
501					  : sizeof(efi_config_table_32_t);
502	}
503	return NULL;
504}
505
506/*
507 * The LINUX_EFI_INITRD_MEDIA_GUID vendor media device path below provides a way
508 * for the firmware or bootloader to expose the initrd data directly to the stub
509 * via the trivial LoadFile2 protocol, which is defined in the UEFI spec, and is
510 * very easy to implement. It is a simple Linux initrd specific conduit between
511 * kernel and firmware, allowing us to put the EFI stub (being part of the
512 * kernel) in charge of where and when to load the initrd, while leaving it up
513 * to the firmware to decide whether it needs to expose its filesystem hierarchy
514 * via EFI protocols.
515 */
516static const struct {
517	struct efi_vendor_dev_path	vendor;
518	struct efi_generic_dev_path	end;
519} __packed initrd_dev_path = {
520	{
521		{
522			EFI_DEV_MEDIA,
523			EFI_DEV_MEDIA_VENDOR,
524			sizeof(struct efi_vendor_dev_path),
525		},
526		LINUX_EFI_INITRD_MEDIA_GUID
527	}, {
528		EFI_DEV_END_PATH,
529		EFI_DEV_END_ENTIRE,
530		sizeof(struct efi_generic_dev_path)
531	}
532};
533
534/**
535 * efi_load_initrd_dev_path() - load the initrd from the Linux initrd device path
536 * @initrd:	pointer of struct to store the address where the initrd was loaded
537 *		and the size of the loaded initrd
538 * @max:	upper limit for the initrd memory allocation
539 *
540 * Return:
541 * * %EFI_SUCCESS if the initrd was loaded successfully, in which
542 *   case @load_addr and @load_size are assigned accordingly
543 * * %EFI_NOT_FOUND if no LoadFile2 protocol exists on the initrd device path
544 * * %EFI_OUT_OF_RESOURCES if memory allocation failed
545 * * %EFI_LOAD_ERROR in all other cases
546 */
547static
548efi_status_t efi_load_initrd_dev_path(struct linux_efi_initrd *initrd,
549				      unsigned long max)
550{
551	efi_guid_t lf2_proto_guid = EFI_LOAD_FILE2_PROTOCOL_GUID;
552	efi_device_path_protocol_t *dp;
553	efi_load_file2_protocol_t *lf2;
554	efi_handle_t handle;
555	efi_status_t status;
556
557	dp = (efi_device_path_protocol_t *)&initrd_dev_path;
558	status = efi_bs_call(locate_device_path, &lf2_proto_guid, &dp, &handle);
559	if (status != EFI_SUCCESS)
560		return status;
561
562	status = efi_bs_call(handle_protocol, handle, &lf2_proto_guid,
563			     (void **)&lf2);
564	if (status != EFI_SUCCESS)
565		return status;
566
567	initrd->size = 0;
568	status = efi_call_proto(lf2, load_file, dp, false, &initrd->size, NULL);
569	if (status != EFI_BUFFER_TOO_SMALL)
570		return EFI_LOAD_ERROR;
571
572	status = efi_allocate_pages(initrd->size, &initrd->base, max);
573	if (status != EFI_SUCCESS)
574		return status;
575
576	status = efi_call_proto(lf2, load_file, dp, false, &initrd->size,
577				(void *)initrd->base);
578	if (status != EFI_SUCCESS) {
579		efi_free(initrd->size, initrd->base);
580		return EFI_LOAD_ERROR;
581	}
582	return EFI_SUCCESS;
583}
584
585static
586efi_status_t efi_load_initrd_cmdline(efi_loaded_image_t *image,
587				     struct linux_efi_initrd *initrd,
588				     unsigned long soft_limit,
589				     unsigned long hard_limit)
590{
591	if (image == NULL)
592		return EFI_UNSUPPORTED;
593
594	return handle_cmdline_files(image, L"initrd=", sizeof(L"initrd=") - 2,
595				    soft_limit, hard_limit,
596				    &initrd->base, &initrd->size);
597}
598
599/**
600 * efi_load_initrd() - Load initial RAM disk
601 * @image:	EFI loaded image protocol
602 * @soft_limit:	preferred address for loading the initrd
603 * @hard_limit:	upper limit address for loading the initrd
604 * @out:	pointer to store the address of the initrd table
605 *
606 * Return:	status code
607 */
608efi_status_t efi_load_initrd(efi_loaded_image_t *image,
609			     unsigned long soft_limit,
610			     unsigned long hard_limit,
611			     const struct linux_efi_initrd **out)
612{
613	efi_guid_t tbl_guid = LINUX_EFI_INITRD_MEDIA_GUID;
614	efi_status_t status = EFI_SUCCESS;
615	struct linux_efi_initrd initrd, *tbl;
616
617	if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD) || efi_noinitrd)
618		return EFI_SUCCESS;
619
620	status = efi_load_initrd_dev_path(&initrd, hard_limit);
621	if (status == EFI_SUCCESS) {
622		efi_info("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n");
623	} else if (status == EFI_NOT_FOUND) {
624		status = efi_load_initrd_cmdline(image, &initrd, soft_limit,
625						 hard_limit);
626		/* command line loader disabled or no initrd= passed? */
627		if (status == EFI_UNSUPPORTED || status == EFI_NOT_READY)
628			return EFI_SUCCESS;
629		if (status == EFI_SUCCESS)
630			efi_info("Loaded initrd from command line option\n");
631	}
632	if (status != EFI_SUCCESS)
633		goto failed;
634
635	if (initrd.size > 0 &&
636	    efi_measure_tagged_event(initrd.base, initrd.size,
637				     EFISTUB_EVT_INITRD) == EFI_SUCCESS)
638		efi_info("Measured initrd data into PCR 9\n");
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 stroke
665 * @usec:	number of microseconds to wait for key stroke
666 * @key:	key entered
667 *
668 * Wait for up to @usec microseconds for a key stroke.
669 *
670 * Return:	status code, EFI_SUCCESS if key received
671 */
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		else
699			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 permissions
709 *                   for code and data
710 *
711 * @image_base:	the base of the image in memory
712 * @alloc_size:	the size of the area in memory occupied by the image
713 * @code_size:	the size of the leading part of the image containing code
714 * 		and read-only data
715 *
716 * efi_remap_image() uses the EFI memory attribute protocol to remap the code
717 * region of the loaded image read-only/executable, and the remainder
718 * read-write/non-executable. The code region is assumed to start at the base
719 * 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's
731	 * invoke it to remap the text/rodata region of the decompressed image
732	 * 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 region
739	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-only
748	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 the
756	// attribute from the code region. Otherwise, set it on the data
757	// 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}