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 #elif defined(CONFIG_RISCV)
44 # define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE_MIN
45 #else
46 # define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE
47 #endif
48 
49 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
50 static bool flat_va_mapping;
51 
52 const efi_system_table_t *efi_system_table;
53 
54 static struct screen_info *setup_graphics(void)
55 {
56 	efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
57 	efi_status_t status;
58 	unsigned long size;
59 	void **gop_handle = NULL;
60 	struct screen_info *si = NULL;
61 
62 	size = 0;
63 	status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
64 			     &gop_proto, NULL, &size, gop_handle);
65 	if (status == EFI_BUFFER_TOO_SMALL) {
66 		si = alloc_screen_info();
67 		if (!si)
68 			return NULL;
69 		status = efi_setup_gop(si, &gop_proto, size);
70 		if (status != EFI_SUCCESS) {
71 			free_screen_info(si);
72 			return NULL;
73 		}
74 	}
75 	return si;
76 }
77 
78 static void install_memreserve_table(void)
79 {
80 	struct linux_efi_memreserve *rsv;
81 	efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
82 	efi_status_t status;
83 
84 	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
85 			     (void **)&rsv);
86 	if (status != EFI_SUCCESS) {
87 		efi_err("Failed to allocate memreserve entry!\n");
88 		return;
89 	}
90 
91 	rsv->next = 0;
92 	rsv->size = 0;
93 	atomic_set(&rsv->count, 0);
94 
95 	status = efi_bs_call(install_configuration_table,
96 			     &memreserve_table_guid, rsv);
97 	if (status != EFI_SUCCESS)
98 		efi_err("Failed to install memreserve config table!\n");
99 }
100 
101 static u32 get_supported_rt_services(void)
102 {
103 	const efi_rt_properties_table_t *rt_prop_table;
104 	u32 supported = EFI_RT_SUPPORTED_ALL;
105 
106 	rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID);
107 	if (rt_prop_table)
108 		supported &= rt_prop_table->runtime_services_supported;
109 
110 	return supported;
111 }
112 
113 /*
114  * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
115  * that is described in the PE/COFF header.  Most of the code is the same
116  * for both archictectures, with the arch-specific code provided in the
117  * handle_kernel_image() function.
118  */
119 efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
120 				   efi_system_table_t *sys_table_arg)
121 {
122 	efi_loaded_image_t *image;
123 	efi_status_t status;
124 	unsigned long image_addr;
125 	unsigned long image_size = 0;
126 	/* addr/point and size pairs for memory management*/
127 	unsigned long initrd_addr = 0;
128 	unsigned long initrd_size = 0;
129 	unsigned long fdt_addr = 0;  /* Original DTB */
130 	unsigned long fdt_size = 0;
131 	char *cmdline_ptr = NULL;
132 	int cmdline_size = 0;
133 	efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
134 	unsigned long reserve_addr = 0;
135 	unsigned long reserve_size = 0;
136 	enum efi_secureboot_mode secure_boot;
137 	struct screen_info *si;
138 	efi_properties_table_t *prop_tbl;
139 
140 	efi_system_table = sys_table_arg;
141 
142 	/* Check if we were booted by the EFI firmware */
143 	if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
144 		status = EFI_INVALID_PARAMETER;
145 		goto fail;
146 	}
147 
148 	status = check_platform_features();
149 	if (status != EFI_SUCCESS)
150 		goto fail;
151 
152 	/*
153 	 * Get a handle to the loaded image protocol.  This is used to get
154 	 * information about the running image, such as size and the command
155 	 * line.
156 	 */
157 	status = efi_system_table->boottime->handle_protocol(handle,
158 					&loaded_image_proto, (void *)&image);
159 	if (status != EFI_SUCCESS) {
160 		efi_err("Failed to get loaded image protocol\n");
161 		goto fail;
162 	}
163 
164 	/*
165 	 * Get the command line from EFI, using the LOADED_IMAGE
166 	 * protocol. We are going to copy the command line into the
167 	 * device tree, so this can be allocated anywhere.
168 	 */
169 	cmdline_ptr = efi_convert_cmdline(image, &cmdline_size);
170 	if (!cmdline_ptr) {
171 		efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
172 		status = EFI_OUT_OF_RESOURCES;
173 		goto fail;
174 	}
175 
176 	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
177 	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
178 	    cmdline_size == 0) {
179 		status = efi_parse_options(CONFIG_CMDLINE);
180 		if (status != EFI_SUCCESS) {
181 			efi_err("Failed to parse options\n");
182 			goto fail_free_cmdline;
183 		}
184 	}
185 
186 	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
187 		status = efi_parse_options(cmdline_ptr);
188 		if (status != EFI_SUCCESS) {
189 			efi_err("Failed to parse options\n");
190 			goto fail_free_cmdline;
191 		}
192 	}
193 
194 	efi_info("Booting Linux Kernel...\n");
195 
196 	si = setup_graphics();
197 
198 	status = handle_kernel_image(&image_addr, &image_size,
199 				     &reserve_addr,
200 				     &reserve_size,
201 				     image);
202 	if (status != EFI_SUCCESS) {
203 		efi_err("Failed to relocate kernel\n");
204 		goto fail_free_screeninfo;
205 	}
206 
207 	efi_retrieve_tpm2_eventlog();
208 
209 	/* Ask the firmware to clear memory on unclean shutdown */
210 	efi_enable_reset_attack_mitigation();
211 
212 	secure_boot = efi_get_secureboot();
213 
214 	/*
215 	 * Unauthenticated device tree data is a security hazard, so ignore
216 	 * 'dtb=' unless UEFI Secure Boot is disabled.  We assume that secure
217 	 * boot is enabled if we can't determine its state.
218 	 */
219 	if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
220 	     secure_boot != efi_secureboot_mode_disabled) {
221 		if (strstr(cmdline_ptr, "dtb="))
222 			efi_err("Ignoring DTB from command line.\n");
223 	} else {
224 		status = efi_load_dtb(image, &fdt_addr, &fdt_size);
225 
226 		if (status != EFI_SUCCESS) {
227 			efi_err("Failed to load device tree!\n");
228 			goto fail_free_image;
229 		}
230 	}
231 
232 	if (fdt_addr) {
233 		efi_info("Using DTB from command line\n");
234 	} else {
235 		/* Look for a device tree configuration table entry. */
236 		fdt_addr = (uintptr_t)get_fdt(&fdt_size);
237 		if (fdt_addr)
238 			efi_info("Using DTB from configuration table\n");
239 	}
240 
241 	if (!fdt_addr)
242 		efi_info("Generating empty DTB\n");
243 
244 	efi_load_initrd(image, &initrd_addr, &initrd_size, ULONG_MAX,
245 			efi_get_max_initrd_addr(image_addr));
246 
247 	efi_random_get_seed();
248 
249 	/*
250 	 * If the NX PE data feature is enabled in the properties table, we
251 	 * should take care not to create a virtual mapping that changes the
252 	 * relative placement of runtime services code and data regions, as
253 	 * they may belong to the same PE/COFF executable image in memory.
254 	 * The easiest way to achieve that is to simply use a 1:1 mapping.
255 	 */
256 	prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
257 	flat_va_mapping = prop_tbl &&
258 			  (prop_tbl->memory_protection_attribute &
259 			   EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
260 
261 	/* force efi_novamap if SetVirtualAddressMap() is unsupported */
262 	efi_novamap |= !(get_supported_rt_services() &
263 			 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);
264 
265 	/* hibernation expects the runtime regions to stay in the same place */
266 	if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) {
267 		/*
268 		 * Randomize the base of the UEFI runtime services region.
269 		 * Preserve the 2 MB alignment of the region by taking a
270 		 * shift of 21 bit positions into account when scaling
271 		 * the headroom value using a 32-bit random value.
272 		 */
273 		static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
274 					    EFI_RT_VIRTUAL_BASE -
275 					    EFI_RT_VIRTUAL_SIZE;
276 		u32 rnd;
277 
278 		status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd);
279 		if (status == EFI_SUCCESS) {
280 			virtmap_base = EFI_RT_VIRTUAL_BASE +
281 				       (((headroom >> 21) * rnd) >> (32 - 21));
282 		}
283 	}
284 
285 	install_memreserve_table();
286 
287 	status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr,
288 						initrd_addr, initrd_size,
289 						cmdline_ptr, fdt_addr, fdt_size);
290 	if (status != EFI_SUCCESS)
291 		goto fail_free_initrd;
292 
293 	if (IS_ENABLED(CONFIG_ARM))
294 		efi_handle_post_ebs_state();
295 
296 	efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));
297 	/* not reached */
298 
299 fail_free_initrd:
300 	efi_err("Failed to update FDT and exit boot services\n");
301 
302 	efi_free(initrd_size, initrd_addr);
303 	efi_free(fdt_size, fdt_addr);
304 
305 fail_free_image:
306 	efi_free(image_size, image_addr);
307 	efi_free(reserve_size, reserve_addr);
308 fail_free_screeninfo:
309 	free_screen_info(si);
310 fail_free_cmdline:
311 	efi_bs_call(free_pool, cmdline_ptr);
312 fail:
313 	return status;
314 }
315 
316 /*
317  * efi_get_virtmap() - create a virtual mapping for the EFI memory map
318  *
319  * This function populates the virt_addr fields of all memory region descriptors
320  * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
321  * are also copied to @runtime_map, and their total count is returned in @count.
322  */
323 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
324 		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
325 		     int *count)
326 {
327 	u64 efi_virt_base = virtmap_base;
328 	efi_memory_desc_t *in, *out = runtime_map;
329 	int l;
330 
331 	for (l = 0; l < map_size; l += desc_size) {
332 		u64 paddr, size;
333 
334 		in = (void *)memory_map + l;
335 		if (!(in->attribute & EFI_MEMORY_RUNTIME))
336 			continue;
337 
338 		paddr = in->phys_addr;
339 		size = in->num_pages * EFI_PAGE_SIZE;
340 
341 		in->virt_addr = in->phys_addr;
342 		if (efi_novamap) {
343 			continue;
344 		}
345 
346 		/*
347 		 * Make the mapping compatible with 64k pages: this allows
348 		 * a 4k page size kernel to kexec a 64k page size kernel and
349 		 * vice versa.
350 		 */
351 		if (!flat_va_mapping) {
352 
353 			paddr = round_down(in->phys_addr, SZ_64K);
354 			size += in->phys_addr - paddr;
355 
356 			/*
357 			 * Avoid wasting memory on PTEs by choosing a virtual
358 			 * base that is compatible with section mappings if this
359 			 * region has the appropriate size and physical
360 			 * alignment. (Sections are 2 MB on 4k granule kernels)
361 			 */
362 			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
363 				efi_virt_base = round_up(efi_virt_base, SZ_2M);
364 			else
365 				efi_virt_base = round_up(efi_virt_base, SZ_64K);
366 
367 			in->virt_addr += efi_virt_base - paddr;
368 			efi_virt_base += size;
369 		}
370 
371 		memcpy(out, in, desc_size);
372 		out = (void *)out + desc_size;
373 		++*count;
374 	}
375 }
376