1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * EFI stub implementation that is shared by arm and arm64 architectures.
4  * This should be #included by the EFI stub implementation files.
5  *
6  * Copyright (C) 2013,2014 Linaro Limited
7  *     Roy Franz <roy.franz@linaro.org
8  * Copyright (C) 2013 Red Hat, Inc.
9  *     Mark Salter <msalter@redhat.com>
10  */
11 
12 #include <linux/efi.h>
13 #include <linux/libfdt.h>
14 #include <asm/efi.h>
15 
16 #include "efistub.h"
17 
18 /*
19  * This is the base address at which to start allocating virtual memory ranges
20  * for UEFI Runtime Services.
21  *
22  * For ARM/ARM64:
23  * This is in the low TTBR0 range so that we can use
24  * any allocation we choose, and eliminate the risk of a conflict after kexec.
25  * The value chosen is the largest non-zero power of 2 suitable for this purpose
26  * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
27  * be mapped efficiently.
28  * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
29  * map everything below 1 GB. (512 MB is a reasonable upper bound for the
30  * entire footprint of the UEFI runtime services memory regions)
31  *
32  * For RISC-V:
33  * There is no specific reason for which, this address (512MB) can't be used
34  * EFI runtime virtual address for RISC-V. It also helps to use EFI runtime
35  * services on both RV32/RV64. Keep the same runtime virtual address for RISC-V
36  * as well to minimize the code churn.
37  */
38 #define EFI_RT_VIRTUAL_BASE	SZ_512M
39 #define EFI_RT_VIRTUAL_SIZE	SZ_512M
40 
41 #ifdef CONFIG_ARM64
42 # define EFI_RT_VIRTUAL_LIMIT	DEFAULT_MAP_WINDOW_64
43 #else
44 # define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE
45 #endif
46 
47 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
48 static bool flat_va_mapping;
49 
50 const efi_system_table_t *efi_system_table;
51 
52 static struct screen_info *setup_graphics(void)
53 {
54 	efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
55 	efi_status_t status;
56 	unsigned long size;
57 	void **gop_handle = NULL;
58 	struct screen_info *si = NULL;
59 
60 	size = 0;
61 	status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
62 			     &gop_proto, NULL, &size, gop_handle);
63 	if (status == EFI_BUFFER_TOO_SMALL) {
64 		si = alloc_screen_info();
65 		if (!si)
66 			return NULL;
67 		status = efi_setup_gop(si, &gop_proto, size);
68 		if (status != EFI_SUCCESS) {
69 			free_screen_info(si);
70 			return NULL;
71 		}
72 	}
73 	return si;
74 }
75 
76 static void install_memreserve_table(void)
77 {
78 	struct linux_efi_memreserve *rsv;
79 	efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
80 	efi_status_t status;
81 
82 	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
83 			     (void **)&rsv);
84 	if (status != EFI_SUCCESS) {
85 		efi_err("Failed to allocate memreserve entry!\n");
86 		return;
87 	}
88 
89 	rsv->next = 0;
90 	rsv->size = 0;
91 	atomic_set(&rsv->count, 0);
92 
93 	status = efi_bs_call(install_configuration_table,
94 			     &memreserve_table_guid, rsv);
95 	if (status != EFI_SUCCESS)
96 		efi_err("Failed to install memreserve config table!\n");
97 }
98 
99 /*
100  * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
101  * that is described in the PE/COFF header.  Most of the code is the same
102  * for both archictectures, with the arch-specific code provided in the
103  * handle_kernel_image() function.
104  */
105 efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
106 				   efi_system_table_t *sys_table_arg)
107 {
108 	efi_loaded_image_t *image;
109 	efi_status_t status;
110 	unsigned long image_addr;
111 	unsigned long image_size = 0;
112 	/* addr/point and size pairs for memory management*/
113 	unsigned long initrd_addr = 0;
114 	unsigned long initrd_size = 0;
115 	unsigned long fdt_addr = 0;  /* Original DTB */
116 	unsigned long fdt_size = 0;
117 	char *cmdline_ptr = NULL;
118 	int cmdline_size = 0;
119 	efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
120 	unsigned long reserve_addr = 0;
121 	unsigned long reserve_size = 0;
122 	enum efi_secureboot_mode secure_boot;
123 	struct screen_info *si;
124 	efi_properties_table_t *prop_tbl;
125 	unsigned long max_addr;
126 
127 	efi_system_table = sys_table_arg;
128 
129 	/* Check if we were booted by the EFI firmware */
130 	if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
131 		status = EFI_INVALID_PARAMETER;
132 		goto fail;
133 	}
134 
135 	status = check_platform_features();
136 	if (status != EFI_SUCCESS)
137 		goto fail;
138 
139 	/*
140 	 * Get a handle to the loaded image protocol.  This is used to get
141 	 * information about the running image, such as size and the command
142 	 * line.
143 	 */
144 	status = efi_system_table->boottime->handle_protocol(handle,
145 					&loaded_image_proto, (void *)&image);
146 	if (status != EFI_SUCCESS) {
147 		efi_err("Failed to get loaded image protocol\n");
148 		goto fail;
149 	}
150 
151 	/*
152 	 * Get the command line from EFI, using the LOADED_IMAGE
153 	 * protocol. We are going to copy the command line into the
154 	 * device tree, so this can be allocated anywhere.
155 	 */
156 	cmdline_ptr = efi_convert_cmdline(image, &cmdline_size);
157 	if (!cmdline_ptr) {
158 		efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
159 		status = EFI_OUT_OF_RESOURCES;
160 		goto fail;
161 	}
162 
163 	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
164 	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
165 	    cmdline_size == 0) {
166 		status = efi_parse_options(CONFIG_CMDLINE);
167 		if (status != EFI_SUCCESS) {
168 			efi_err("Failed to parse options\n");
169 			goto fail_free_cmdline;
170 		}
171 	}
172 
173 	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
174 		status = efi_parse_options(cmdline_ptr);
175 		if (status != EFI_SUCCESS) {
176 			efi_err("Failed to parse options\n");
177 			goto fail_free_cmdline;
178 		}
179 	}
180 
181 	efi_info("Booting Linux Kernel...\n");
182 
183 	si = setup_graphics();
184 
185 	status = handle_kernel_image(&image_addr, &image_size,
186 				     &reserve_addr,
187 				     &reserve_size,
188 				     image);
189 	if (status != EFI_SUCCESS) {
190 		efi_err("Failed to relocate kernel\n");
191 		goto fail_free_screeninfo;
192 	}
193 
194 	efi_retrieve_tpm2_eventlog();
195 
196 	/* Ask the firmware to clear memory on unclean shutdown */
197 	efi_enable_reset_attack_mitigation();
198 
199 	secure_boot = efi_get_secureboot();
200 
201 	/*
202 	 * Unauthenticated device tree data is a security hazard, so ignore
203 	 * 'dtb=' unless UEFI Secure Boot is disabled.  We assume that secure
204 	 * boot is enabled if we can't determine its state.
205 	 */
206 	if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
207 	     secure_boot != efi_secureboot_mode_disabled) {
208 		if (strstr(cmdline_ptr, "dtb="))
209 			efi_err("Ignoring DTB from command line.\n");
210 	} else {
211 		status = efi_load_dtb(image, &fdt_addr, &fdt_size);
212 
213 		if (status != EFI_SUCCESS) {
214 			efi_err("Failed to load device tree!\n");
215 			goto fail_free_image;
216 		}
217 	}
218 
219 	if (fdt_addr) {
220 		efi_info("Using DTB from command line\n");
221 	} else {
222 		/* Look for a device tree configuration table entry. */
223 		fdt_addr = (uintptr_t)get_fdt(&fdt_size);
224 		if (fdt_addr)
225 			efi_info("Using DTB from configuration table\n");
226 	}
227 
228 	if (!fdt_addr)
229 		efi_info("Generating empty DTB\n");
230 
231 	if (!efi_noinitrd) {
232 		max_addr = efi_get_max_initrd_addr(image_addr);
233 		status = efi_load_initrd(image, &initrd_addr, &initrd_size,
234 					 ULONG_MAX, max_addr);
235 		if (status != EFI_SUCCESS)
236 			efi_err("Failed to load initrd!\n");
237 	}
238 
239 	efi_random_get_seed();
240 
241 	/*
242 	 * If the NX PE data feature is enabled in the properties table, we
243 	 * should take care not to create a virtual mapping that changes the
244 	 * relative placement of runtime services code and data regions, as
245 	 * they may belong to the same PE/COFF executable image in memory.
246 	 * The easiest way to achieve that is to simply use a 1:1 mapping.
247 	 */
248 	prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
249 	flat_va_mapping = prop_tbl &&
250 			  (prop_tbl->memory_protection_attribute &
251 			   EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
252 
253 	/* hibernation expects the runtime regions to stay in the same place */
254 	if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) {
255 		/*
256 		 * Randomize the base of the UEFI runtime services region.
257 		 * Preserve the 2 MB alignment of the region by taking a
258 		 * shift of 21 bit positions into account when scaling
259 		 * the headroom value using a 32-bit random value.
260 		 */
261 		static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
262 					    EFI_RT_VIRTUAL_BASE -
263 					    EFI_RT_VIRTUAL_SIZE;
264 		u32 rnd;
265 
266 		status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd);
267 		if (status == EFI_SUCCESS) {
268 			virtmap_base = EFI_RT_VIRTUAL_BASE +
269 				       (((headroom >> 21) * rnd) >> (32 - 21));
270 		}
271 	}
272 
273 	install_memreserve_table();
274 
275 	status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr,
276 						initrd_addr, initrd_size,
277 						cmdline_ptr, fdt_addr, fdt_size);
278 	if (status != EFI_SUCCESS)
279 		goto fail_free_initrd;
280 
281 	if (IS_ENABLED(CONFIG_ARM))
282 		efi_handle_post_ebs_state();
283 
284 	efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));
285 	/* not reached */
286 
287 fail_free_initrd:
288 	efi_err("Failed to update FDT and exit boot services\n");
289 
290 	efi_free(initrd_size, initrd_addr);
291 	efi_free(fdt_size, fdt_addr);
292 
293 fail_free_image:
294 	efi_free(image_size, image_addr);
295 	efi_free(reserve_size, reserve_addr);
296 fail_free_screeninfo:
297 	free_screen_info(si);
298 fail_free_cmdline:
299 	efi_bs_call(free_pool, cmdline_ptr);
300 fail:
301 	return status;
302 }
303 
304 /*
305  * efi_get_virtmap() - create a virtual mapping for the EFI memory map
306  *
307  * This function populates the virt_addr fields of all memory region descriptors
308  * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
309  * are also copied to @runtime_map, and their total count is returned in @count.
310  */
311 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
312 		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
313 		     int *count)
314 {
315 	u64 efi_virt_base = virtmap_base;
316 	efi_memory_desc_t *in, *out = runtime_map;
317 	int l;
318 
319 	for (l = 0; l < map_size; l += desc_size) {
320 		u64 paddr, size;
321 
322 		in = (void *)memory_map + l;
323 		if (!(in->attribute & EFI_MEMORY_RUNTIME))
324 			continue;
325 
326 		paddr = in->phys_addr;
327 		size = in->num_pages * EFI_PAGE_SIZE;
328 
329 		in->virt_addr = in->phys_addr;
330 		if (efi_novamap) {
331 			continue;
332 		}
333 
334 		/*
335 		 * Make the mapping compatible with 64k pages: this allows
336 		 * a 4k page size kernel to kexec a 64k page size kernel and
337 		 * vice versa.
338 		 */
339 		if (!flat_va_mapping) {
340 
341 			paddr = round_down(in->phys_addr, SZ_64K);
342 			size += in->phys_addr - paddr;
343 
344 			/*
345 			 * Avoid wasting memory on PTEs by choosing a virtual
346 			 * base that is compatible with section mappings if this
347 			 * region has the appropriate size and physical
348 			 * alignment. (Sections are 2 MB on 4k granule kernels)
349 			 */
350 			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
351 				efi_virt_base = round_up(efi_virt_base, SZ_2M);
352 			else
353 				efi_virt_base = round_up(efi_virt_base, SZ_64K);
354 
355 			in->virt_addr += efi_virt_base - paddr;
356 			efi_virt_base += size;
357 		}
358 
359 		memcpy(out, in, desc_size);
360 		out = (void *)out + desc_size;
361 		++*count;
362 	}
363 }
364