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 <asm/efi.h>
14 
15 #include "efistub.h"
16 
17 /*
18  * This is the base address at which to start allocating virtual memory ranges
19  * for UEFI Runtime Services.
20  *
21  * For ARM/ARM64:
22  * This is in the low TTBR0 range so that we can use
23  * any allocation we choose, and eliminate the risk of a conflict after kexec.
24  * The value chosen is the largest non-zero power of 2 suitable for this purpose
25  * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
26  * be mapped efficiently.
27  * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
28  * map everything below 1 GB. (512 MB is a reasonable upper bound for the
29  * entire footprint of the UEFI runtime services memory regions)
30  *
31  * For RISC-V:
32  * There is no specific reason for which, this address (512MB) can't be used
33  * EFI runtime virtual address for RISC-V. It also helps to use EFI runtime
34  * services on both RV32/RV64. Keep the same runtime virtual address for RISC-V
35  * as well to minimize the code churn.
36  */
37 #define EFI_RT_VIRTUAL_BASE	SZ_512M
38 
39 /*
40  * Some architectures map the EFI regions into the kernel's linear map using a
41  * fixed offset.
42  */
43 #ifndef EFI_RT_VIRTUAL_OFFSET
44 #define EFI_RT_VIRTUAL_OFFSET	0
45 #endif
46 
47 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
48 static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0);
49 
50 struct screen_info * __weak alloc_screen_info(void)
51 {
52 	return &screen_info;
53 }
54 
55 void __weak free_screen_info(struct screen_info *si)
56 {
57 }
58 
59 static struct screen_info *setup_graphics(void)
60 {
61 	efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
62 	efi_status_t status;
63 	unsigned long size;
64 	void **gop_handle = NULL;
65 	struct screen_info *si = NULL;
66 
67 	size = 0;
68 	status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
69 			     &gop_proto, NULL, &size, gop_handle);
70 	if (status == EFI_BUFFER_TOO_SMALL) {
71 		si = alloc_screen_info();
72 		if (!si)
73 			return NULL;
74 		status = efi_setup_gop(si, &gop_proto, size);
75 		if (status != EFI_SUCCESS) {
76 			free_screen_info(si);
77 			return NULL;
78 		}
79 	}
80 	return si;
81 }
82 
83 static void install_memreserve_table(void)
84 {
85 	struct linux_efi_memreserve *rsv;
86 	efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
87 	efi_status_t status;
88 
89 	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
90 			     (void **)&rsv);
91 	if (status != EFI_SUCCESS) {
92 		efi_err("Failed to allocate memreserve entry!\n");
93 		return;
94 	}
95 
96 	rsv->next = 0;
97 	rsv->size = 0;
98 	atomic_set(&rsv->count, 0);
99 
100 	status = efi_bs_call(install_configuration_table,
101 			     &memreserve_table_guid, rsv);
102 	if (status != EFI_SUCCESS)
103 		efi_err("Failed to install memreserve config table!\n");
104 }
105 
106 static u32 get_supported_rt_services(void)
107 {
108 	const efi_rt_properties_table_t *rt_prop_table;
109 	u32 supported = EFI_RT_SUPPORTED_ALL;
110 
111 	rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID);
112 	if (rt_prop_table)
113 		supported &= rt_prop_table->runtime_services_supported;
114 
115 	return supported;
116 }
117 
118 efi_status_t efi_handle_cmdline(efi_loaded_image_t *image, char **cmdline_ptr)
119 {
120 	int cmdline_size = 0;
121 	efi_status_t status;
122 	char *cmdline;
123 
124 	/*
125 	 * Get the command line from EFI, using the LOADED_IMAGE
126 	 * protocol. We are going to copy the command line into the
127 	 * device tree, so this can be allocated anywhere.
128 	 */
129 	cmdline = efi_convert_cmdline(image, &cmdline_size);
130 	if (!cmdline) {
131 		efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
132 		return EFI_OUT_OF_RESOURCES;
133 	}
134 
135 	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
136 	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
137 	    cmdline_size == 0) {
138 		status = efi_parse_options(CONFIG_CMDLINE);
139 		if (status != EFI_SUCCESS) {
140 			efi_err("Failed to parse options\n");
141 			goto fail_free_cmdline;
142 		}
143 	}
144 
145 	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
146 		status = efi_parse_options(cmdline);
147 		if (status != EFI_SUCCESS) {
148 			efi_err("Failed to parse options\n");
149 			goto fail_free_cmdline;
150 		}
151 	}
152 
153 	*cmdline_ptr = cmdline;
154 	return EFI_SUCCESS;
155 
156 fail_free_cmdline:
157 	efi_bs_call(free_pool, cmdline_ptr);
158 	return status;
159 }
160 
161 efi_status_t efi_stub_common(efi_handle_t handle,
162 			     efi_loaded_image_t *image,
163 			     unsigned long image_addr,
164 			     char *cmdline_ptr)
165 {
166 	struct screen_info *si;
167 	efi_status_t status;
168 
169 	status = check_platform_features();
170 	if (status != EFI_SUCCESS)
171 		return status;
172 
173 	si = setup_graphics();
174 
175 	efi_retrieve_tpm2_eventlog();
176 
177 	/* Ask the firmware to clear memory on unclean shutdown */
178 	efi_enable_reset_attack_mitigation();
179 
180 	efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr),
181 			NULL);
182 
183 	efi_random_get_seed();
184 
185 	/* force efi_novamap if SetVirtualAddressMap() is unsupported */
186 	efi_novamap |= !(get_supported_rt_services() &
187 			 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);
188 
189 	install_memreserve_table();
190 
191 	status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr);
192 
193 	free_screen_info(si);
194 	return status;
195 }
196 
197 /*
198  * efi_allocate_virtmap() - create a pool allocation for the virtmap
199  *
200  * Create an allocation that is of sufficient size to hold all the memory
201  * descriptors that will be passed to SetVirtualAddressMap() to inform the
202  * firmware about the virtual mapping that will be used under the OS to call
203  * into the firmware.
204  */
205 efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap,
206 			       unsigned long *desc_size, u32 *desc_ver)
207 {
208 	unsigned long size, mmap_key;
209 	efi_status_t status;
210 
211 	/*
212 	 * Use the size of the current memory map as an upper bound for the
213 	 * size of the buffer we need to pass to SetVirtualAddressMap() to
214 	 * cover all EFI_MEMORY_RUNTIME regions.
215 	 */
216 	size = 0;
217 	status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size,
218 			     desc_ver);
219 	if (status != EFI_BUFFER_TOO_SMALL)
220 		return EFI_LOAD_ERROR;
221 
222 	return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
223 			   (void **)virtmap);
224 }
225 
226 /*
227  * efi_get_virtmap() - create a virtual mapping for the EFI memory map
228  *
229  * This function populates the virt_addr fields of all memory region descriptors
230  * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
231  * are also copied to @runtime_map, and their total count is returned in @count.
232  */
233 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
234 		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
235 		     int *count)
236 {
237 	u64 efi_virt_base = virtmap_base;
238 	efi_memory_desc_t *in, *out = runtime_map;
239 	int l;
240 
241 	*count = 0;
242 
243 	for (l = 0; l < map_size; l += desc_size) {
244 		u64 paddr, size;
245 
246 		in = (void *)memory_map + l;
247 		if (!(in->attribute & EFI_MEMORY_RUNTIME))
248 			continue;
249 
250 		paddr = in->phys_addr;
251 		size = in->num_pages * EFI_PAGE_SIZE;
252 
253 		in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET;
254 		if (efi_novamap) {
255 			continue;
256 		}
257 
258 		/*
259 		 * Make the mapping compatible with 64k pages: this allows
260 		 * a 4k page size kernel to kexec a 64k page size kernel and
261 		 * vice versa.
262 		 */
263 		if (!flat_va_mapping) {
264 
265 			paddr = round_down(in->phys_addr, SZ_64K);
266 			size += in->phys_addr - paddr;
267 
268 			/*
269 			 * Avoid wasting memory on PTEs by choosing a virtual
270 			 * base that is compatible with section mappings if this
271 			 * region has the appropriate size and physical
272 			 * alignment. (Sections are 2 MB on 4k granule kernels)
273 			 */
274 			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
275 				efi_virt_base = round_up(efi_virt_base, SZ_2M);
276 			else
277 				efi_virt_base = round_up(efi_virt_base, SZ_64K);
278 
279 			in->virt_addr += efi_virt_base - paddr;
280 			efi_virt_base += size;
281 		}
282 
283 		memcpy(out, in, desc_size);
284 		out = (void *)out + desc_size;
285 		++*count;
286 	}
287 }
288