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 #define EFI_RT_VIRTUAL_SIZE SZ_512M
39
40 #ifdef CONFIG_ARM64
41 # define EFI_RT_VIRTUAL_LIMIT DEFAULT_MAP_WINDOW_64
42 #elif defined(CONFIG_RISCV) || defined(CONFIG_LOONGARCH)
43 # define EFI_RT_VIRTUAL_LIMIT TASK_SIZE_MIN
44 #else /* Only if TASK_SIZE is a constant */
45 # define EFI_RT_VIRTUAL_LIMIT TASK_SIZE
46 #endif
47
48 /*
49 * Some architectures map the EFI regions into the kernel's linear map using a
50 * fixed offset.
51 */
52 #ifndef EFI_RT_VIRTUAL_OFFSET
53 #define EFI_RT_VIRTUAL_OFFSET 0
54 #endif
55
56 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
57 static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0);
58
setup_graphics(void)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
install_memreserve_table(void)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
get_supported_rt_services(void)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 /*
119 * EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint
120 * that is described in the PE/COFF header. Most of the code is the same
121 * for both archictectures, with the arch-specific code provided in the
122 * handle_kernel_image() function.
123 */
efi_pe_entry(efi_handle_t handle,efi_system_table_t * sys_table_arg)124 efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
125 efi_system_table_t *sys_table_arg)
126 {
127 efi_loaded_image_t *image;
128 efi_status_t status;
129 unsigned long image_addr;
130 unsigned long image_size = 0;
131 /* addr/point and size pairs for memory management*/
132 char *cmdline_ptr = NULL;
133 int cmdline_size = 0;
134 efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
135 unsigned long reserve_addr = 0;
136 unsigned long reserve_size = 0;
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_bs_call(handle_protocol, handle, &loaded_image_proto,
158 (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, handle);
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 efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr),
213 NULL);
214
215 efi_random_get_seed();
216
217 /*
218 * If the NX PE data feature is enabled in the properties table, we
219 * should take care not to create a virtual mapping that changes the
220 * relative placement of runtime services code and data regions, as
221 * they may belong to the same PE/COFF executable image in memory.
222 * The easiest way to achieve that is to simply use a 1:1 mapping.
223 */
224 prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
225 flat_va_mapping |= prop_tbl &&
226 (prop_tbl->memory_protection_attribute &
227 EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
228
229 /* force efi_novamap if SetVirtualAddressMap() is unsupported */
230 efi_novamap |= !(get_supported_rt_services() &
231 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);
232
233 /* hibernation expects the runtime regions to stay in the same place */
234 if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) {
235 /*
236 * Randomize the base of the UEFI runtime services region.
237 * Preserve the 2 MB alignment of the region by taking a
238 * shift of 21 bit positions into account when scaling
239 * the headroom value using a 32-bit random value.
240 */
241 static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
242 EFI_RT_VIRTUAL_BASE -
243 EFI_RT_VIRTUAL_SIZE;
244 u32 rnd;
245
246 status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd);
247 if (status == EFI_SUCCESS) {
248 virtmap_base = EFI_RT_VIRTUAL_BASE +
249 (((headroom >> 21) * rnd) >> (32 - 21));
250 }
251 }
252
253 install_memreserve_table();
254
255 status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr);
256
257 efi_free(image_size, image_addr);
258 efi_free(reserve_size, reserve_addr);
259 fail_free_screeninfo:
260 free_screen_info(si);
261 fail_free_cmdline:
262 efi_bs_call(free_pool, cmdline_ptr);
263 fail:
264 return status;
265 }
266
267 /*
268 * efi_allocate_virtmap() - create a pool allocation for the virtmap
269 *
270 * Create an allocation that is of sufficient size to hold all the memory
271 * descriptors that will be passed to SetVirtualAddressMap() to inform the
272 * firmware about the virtual mapping that will be used under the OS to call
273 * into the firmware.
274 */
efi_alloc_virtmap(efi_memory_desc_t ** virtmap,unsigned long * desc_size,u32 * desc_ver)275 efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap,
276 unsigned long *desc_size, u32 *desc_ver)
277 {
278 unsigned long size, mmap_key;
279 efi_status_t status;
280
281 /*
282 * Use the size of the current memory map as an upper bound for the
283 * size of the buffer we need to pass to SetVirtualAddressMap() to
284 * cover all EFI_MEMORY_RUNTIME regions.
285 */
286 size = 0;
287 status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size,
288 desc_ver);
289 if (status != EFI_BUFFER_TOO_SMALL)
290 return EFI_LOAD_ERROR;
291
292 return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
293 (void **)virtmap);
294 }
295
296 /*
297 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
298 *
299 * This function populates the virt_addr fields of all memory region descriptors
300 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
301 * are also copied to @runtime_map, and their total count is returned in @count.
302 */
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)303 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
304 unsigned long desc_size, efi_memory_desc_t *runtime_map,
305 int *count)
306 {
307 u64 efi_virt_base = virtmap_base;
308 efi_memory_desc_t *in, *out = runtime_map;
309 int l;
310
311 *count = 0;
312
313 for (l = 0; l < map_size; l += desc_size) {
314 u64 paddr, size;
315
316 in = (void *)memory_map + l;
317 if (!(in->attribute & EFI_MEMORY_RUNTIME))
318 continue;
319
320 paddr = in->phys_addr;
321 size = in->num_pages * EFI_PAGE_SIZE;
322
323 in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET;
324 if (efi_novamap) {
325 continue;
326 }
327
328 /*
329 * Make the mapping compatible with 64k pages: this allows
330 * a 4k page size kernel to kexec a 64k page size kernel and
331 * vice versa.
332 */
333 if (!flat_va_mapping) {
334
335 paddr = round_down(in->phys_addr, SZ_64K);
336 size += in->phys_addr - paddr;
337
338 /*
339 * Avoid wasting memory on PTEs by choosing a virtual
340 * base that is compatible with section mappings if this
341 * region has the appropriate size and physical
342 * alignment. (Sections are 2 MB on 4k granule kernels)
343 */
344 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
345 efi_virt_base = round_up(efi_virt_base, SZ_2M);
346 else
347 efi_virt_base = round_up(efi_virt_base, SZ_64K);
348
349 in->virt_addr += efi_virt_base - paddr;
350 efi_virt_base += size;
351 }
352
353 memcpy(out, in, desc_size);
354 out = (void *)out + desc_size;
355 ++*count;
356 }
357 }
358