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
free_screen_info(struct screen_info * si)50 void __weak free_screen_info(struct screen_info *si)
51 {
52 }
53
setup_graphics(void)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
install_memreserve_table(void)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
get_supported_rt_services(void)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
efi_handle_cmdline(efi_loaded_image_t * image,char ** cmdline_ptr)113 efi_status_t efi_handle_cmdline(efi_loaded_image_t *image, char **cmdline_ptr)
114 {
115 int cmdline_size = 0;
116 efi_status_t status;
117 char *cmdline;
118
119 /*
120 * Get the command line from EFI, using the LOADED_IMAGE
121 * protocol. We are going to copy the command line into the
122 * device tree, so this can be allocated anywhere.
123 */
124 cmdline = efi_convert_cmdline(image, &cmdline_size);
125 if (!cmdline) {
126 efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
127 return EFI_OUT_OF_RESOURCES;
128 }
129
130 if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
131 IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
132 cmdline_size == 0) {
133 status = efi_parse_options(CONFIG_CMDLINE);
134 if (status != EFI_SUCCESS) {
135 efi_err("Failed to parse options\n");
136 goto fail_free_cmdline;
137 }
138 }
139
140 if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
141 status = efi_parse_options(cmdline);
142 if (status != EFI_SUCCESS) {
143 efi_err("Failed to parse options\n");
144 goto fail_free_cmdline;
145 }
146 }
147
148 *cmdline_ptr = cmdline;
149 return EFI_SUCCESS;
150
151 fail_free_cmdline:
152 efi_bs_call(free_pool, cmdline_ptr);
153 return status;
154 }
155
efi_stub_common(efi_handle_t handle,efi_loaded_image_t * image,unsigned long image_addr,char * cmdline_ptr)156 efi_status_t efi_stub_common(efi_handle_t handle,
157 efi_loaded_image_t *image,
158 unsigned long image_addr,
159 char *cmdline_ptr)
160 {
161 struct screen_info *si;
162 efi_status_t status;
163
164 status = check_platform_features();
165 if (status != EFI_SUCCESS)
166 return status;
167
168 si = setup_graphics();
169
170 efi_retrieve_tpm2_eventlog();
171
172 /* Ask the firmware to clear memory on unclean shutdown */
173 efi_enable_reset_attack_mitigation();
174
175 efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr),
176 NULL);
177
178 efi_random_get_seed();
179
180 /* force efi_novamap if SetVirtualAddressMap() is unsupported */
181 efi_novamap |= !(get_supported_rt_services() &
182 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);
183
184 install_memreserve_table();
185
186 status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr);
187
188 free_screen_info(si);
189 return status;
190 }
191
192 /*
193 * efi_allocate_virtmap() - create a pool allocation for the virtmap
194 *
195 * Create an allocation that is of sufficient size to hold all the memory
196 * descriptors that will be passed to SetVirtualAddressMap() to inform the
197 * firmware about the virtual mapping that will be used under the OS to call
198 * into the firmware.
199 */
efi_alloc_virtmap(efi_memory_desc_t ** virtmap,unsigned long * desc_size,u32 * desc_ver)200 efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap,
201 unsigned long *desc_size, u32 *desc_ver)
202 {
203 unsigned long size, mmap_key;
204 efi_status_t status;
205
206 /*
207 * Use the size of the current memory map as an upper bound for the
208 * size of the buffer we need to pass to SetVirtualAddressMap() to
209 * cover all EFI_MEMORY_RUNTIME regions.
210 */
211 size = 0;
212 status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size,
213 desc_ver);
214 if (status != EFI_BUFFER_TOO_SMALL)
215 return EFI_LOAD_ERROR;
216
217 return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
218 (void **)virtmap);
219 }
220
221 /*
222 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
223 *
224 * This function populates the virt_addr fields of all memory region descriptors
225 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
226 * are also copied to @runtime_map, and their total count is returned in @count.
227 */
efi_get_virtmap(efi_memory_desc_t * memory_map,unsigned long map_size,unsigned long desc_size,efi_memory_desc_t * runtime_map,int * count)228 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
229 unsigned long desc_size, efi_memory_desc_t *runtime_map,
230 int *count)
231 {
232 u64 efi_virt_base = virtmap_base;
233 efi_memory_desc_t *in, *out = runtime_map;
234 int l;
235
236 *count = 0;
237
238 for (l = 0; l < map_size; l += desc_size) {
239 u64 paddr, size;
240
241 in = (void *)memory_map + l;
242 if (!(in->attribute & EFI_MEMORY_RUNTIME))
243 continue;
244
245 paddr = in->phys_addr;
246 size = in->num_pages * EFI_PAGE_SIZE;
247
248 in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET;
249 if (efi_novamap) {
250 continue;
251 }
252
253 /*
254 * Make the mapping compatible with 64k pages: this allows
255 * a 4k page size kernel to kexec a 64k page size kernel and
256 * vice versa.
257 */
258 if (!flat_va_mapping) {
259
260 paddr = round_down(in->phys_addr, SZ_64K);
261 size += in->phys_addr - paddr;
262
263 /*
264 * Avoid wasting memory on PTEs by choosing a virtual
265 * base that is compatible with section mappings if this
266 * region has the appropriate size and physical
267 * alignment. (Sections are 2 MB on 4k granule kernels)
268 */
269 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
270 efi_virt_base = round_up(efi_virt_base, SZ_2M);
271 else
272 efi_virt_base = round_up(efi_virt_base, SZ_64K);
273
274 in->virt_addr += efi_virt_base - paddr;
275 efi_virt_base += size;
276 }
277
278 memcpy(out, in, desc_size);
279 out = (void *)out + desc_size;
280 ++*count;
281 }
282 }
283