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
setup_graphics(void)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
install_memreserve_table(void)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 */
efi_pe_entry(efi_handle_t handle,efi_system_table_t * sys_table_arg)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 efi_get_max_fdt_addr(image_addr),
277 initrd_addr, initrd_size,
278 cmdline_ptr, fdt_addr, fdt_size);
279 if (status != EFI_SUCCESS)
280 goto fail_free_initrd;
281
282 if (IS_ENABLED(CONFIG_ARM))
283 efi_handle_post_ebs_state();
284
285 efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));
286 /* not reached */
287
288 fail_free_initrd:
289 efi_err("Failed to update FDT and exit boot services\n");
290
291 efi_free(initrd_size, initrd_addr);
292 efi_free(fdt_size, fdt_addr);
293
294 fail_free_image:
295 efi_free(image_size, image_addr);
296 efi_free(reserve_size, reserve_addr);
297 fail_free_screeninfo:
298 free_screen_info(si);
299 fail_free_cmdline:
300 efi_bs_call(free_pool, cmdline_ptr);
301 fail:
302 return status;
303 }
304
305 /*
306 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
307 *
308 * This function populates the virt_addr fields of all memory region descriptors
309 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
310 * are also copied to @runtime_map, and their total count is returned in @count.
311 */
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)312 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
313 unsigned long desc_size, efi_memory_desc_t *runtime_map,
314 int *count)
315 {
316 u64 efi_virt_base = virtmap_base;
317 efi_memory_desc_t *in, *out = runtime_map;
318 int l;
319
320 for (l = 0; l < map_size; l += desc_size) {
321 u64 paddr, size;
322
323 in = (void *)memory_map + l;
324 if (!(in->attribute & EFI_MEMORY_RUNTIME))
325 continue;
326
327 paddr = in->phys_addr;
328 size = in->num_pages * EFI_PAGE_SIZE;
329
330 in->virt_addr = in->phys_addr;
331 if (efi_novamap) {
332 continue;
333 }
334
335 /*
336 * Make the mapping compatible with 64k pages: this allows
337 * a 4k page size kernel to kexec a 64k page size kernel and
338 * vice versa.
339 */
340 if (!flat_va_mapping) {
341
342 paddr = round_down(in->phys_addr, SZ_64K);
343 size += in->phys_addr - paddr;
344
345 /*
346 * Avoid wasting memory on PTEs by choosing a virtual
347 * base that is compatible with section mappings if this
348 * region has the appropriate size and physical
349 * alignment. (Sections are 2 MB on 4k granule kernels)
350 */
351 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
352 efi_virt_base = round_up(efi_virt_base, SZ_2M);
353 else
354 efi_virt_base = round_up(efi_virt_base, SZ_64K);
355
356 in->virt_addr += efi_virt_base - paddr;
357 efi_virt_base += size;
358 }
359
360 memcpy(out, in, desc_size);
361 out = (void *)out + desc_size;
362 ++*count;
363 }
364 }
365
