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