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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. This is in the low TTBR0 range so that we can use
21 * any allocation we choose, and eliminate the risk of a conflict after kexec.
22 * The value chosen is the largest non-zero power of 2 suitable for this purpose
23 * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
24 * be mapped efficiently.
25 * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
26 * map everything below 1 GB. (512 MB is a reasonable upper bound for the
27 * entire footprint of the UEFI runtime services memory regions)
28 */
29#define EFI_RT_VIRTUAL_BASE SZ_512M
30#define EFI_RT_VIRTUAL_SIZE SZ_512M
31
32#ifdef CONFIG_ARM64
33# define EFI_RT_VIRTUAL_LIMIT DEFAULT_MAP_WINDOW_64
34#else
35# define EFI_RT_VIRTUAL_LIMIT TASK_SIZE
36#endif
37
38static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
39static bool flat_va_mapping;
40
41const efi_system_table_t *efi_system_table;
42
43static struct screen_info *setup_graphics(void)
44{
45 efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
46 efi_status_t status;
47 unsigned long size;
48 void **gop_handle = NULL;
49 struct screen_info *si = NULL;
50
51 size = 0;
52 status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
53 &gop_proto, NULL, &size, gop_handle);
54 if (status == EFI_BUFFER_TOO_SMALL) {
55 si = alloc_screen_info();
56 if (!si)
57 return NULL;
58 status = efi_setup_gop(si, &gop_proto, size);
59 if (status != EFI_SUCCESS) {
60 free_screen_info(si);
61 return NULL;
62 }
63 }
64 return si;
65}
66
67static void install_memreserve_table(void)
68{
69 struct linux_efi_memreserve *rsv;
70 efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
71 efi_status_t status;
72
73 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
74 (void **)&rsv);
75 if (status != EFI_SUCCESS) {
76 efi_err("Failed to allocate memreserve entry!\n");
77 return;
78 }
79
80 rsv->next = 0;
81 rsv->size = 0;
82 atomic_set(&rsv->count, 0);
83
84 status = efi_bs_call(install_configuration_table,
85 &memreserve_table_guid, rsv);
86 if (status != EFI_SUCCESS)
87 efi_err("Failed to install memreserve config table!\n");
88}
89
90static unsigned long get_dram_base(void)
91{
92 efi_status_t status;
93 unsigned long map_size, buff_size;
94 unsigned long membase = EFI_ERROR;
95 struct efi_memory_map map;
96 efi_memory_desc_t *md;
97 struct efi_boot_memmap boot_map;
98
99 boot_map.map = (efi_memory_desc_t **)&map.map;
100 boot_map.map_size = &map_size;
101 boot_map.desc_size = &map.desc_size;
102 boot_map.desc_ver = NULL;
103 boot_map.key_ptr = NULL;
104 boot_map.buff_size = &buff_size;
105
106 status = efi_get_memory_map(&boot_map);
107 if (status != EFI_SUCCESS)
108 return membase;
109
110 map.map_end = map.map + map_size;
111
112 for_each_efi_memory_desc_in_map(&map, md) {
113 if (md->attribute & EFI_MEMORY_WB) {
114 if (membase > md->phys_addr)
115 membase = md->phys_addr;
116 }
117 }
118
119 efi_bs_call(free_pool, map.map);
120
121 return membase;
122}
123
124/*
125 * EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint
126 * that is described in the PE/COFF header. Most of the code is the same
127 * for both archictectures, with the arch-specific code provided in the
128 * handle_kernel_image() function.
129 */
130efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
131 efi_system_table_t *sys_table_arg)
132{
133 efi_loaded_image_t *image;
134 efi_status_t status;
135 unsigned long image_addr;
136 unsigned long image_size = 0;
137 unsigned long dram_base;
138 /* addr/point and size pairs for memory management*/
139 unsigned long initrd_addr = 0;
140 unsigned long initrd_size = 0;
141 unsigned long fdt_addr = 0; /* Original DTB */
142 unsigned long fdt_size = 0;
143 char *cmdline_ptr = NULL;
144 int cmdline_size = 0;
145 efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
146 unsigned long reserve_addr = 0;
147 unsigned long reserve_size = 0;
148 enum efi_secureboot_mode secure_boot;
149 struct screen_info *si;
150 efi_properties_table_t *prop_tbl;
151 unsigned long max_addr;
152
153 efi_system_table = sys_table_arg;
154
155 /* Check if we were booted by the EFI firmware */
156 if (efi_system_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) {
157 status = EFI_INVALID_PARAMETER;
158 goto fail;
159 }
160
161 status = check_platform_features();
162 if (status != EFI_SUCCESS)
163 goto fail;
164
165 /*
166 * Get a handle to the loaded image protocol. This is used to get
167 * information about the running image, such as size and the command
168 * line.
169 */
170 status = efi_system_table->boottime->handle_protocol(handle,
171 &loaded_image_proto, (void *)&image);
172 if (status != EFI_SUCCESS) {
173 efi_err("Failed to get loaded image protocol\n");
174 goto fail;
175 }
176
177 dram_base = get_dram_base();
178 if (dram_base == EFI_ERROR) {
179 efi_err("Failed to find DRAM base\n");
180 status = EFI_LOAD_ERROR;
181 goto fail;
182 }
183
184 /*
185 * Get the command line from EFI, using the LOADED_IMAGE
186 * protocol. We are going to copy the command line into the
187 * device tree, so this can be allocated anywhere.
188 */
189 cmdline_ptr = efi_convert_cmdline(image, &cmdline_size);
190 if (!cmdline_ptr) {
191 efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
192 status = EFI_OUT_OF_RESOURCES;
193 goto fail;
194 }
195
196 if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
197 IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
198 cmdline_size == 0) {
199 status = efi_parse_options(CONFIG_CMDLINE);
200 if (status != EFI_SUCCESS) {
201 efi_err("Failed to parse options\n");
202 goto fail_free_cmdline;
203 }
204 }
205
206 if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
207 status = efi_parse_options(cmdline_ptr);
208 if (status != EFI_SUCCESS) {
209 efi_err("Failed to parse options\n");
210 goto fail_free_cmdline;
211 }
212 }
213
214 efi_info("Booting Linux Kernel...\n");
215
216 si = setup_graphics();
217
218 status = handle_kernel_image(&image_addr, &image_size,
219 &reserve_addr,
220 &reserve_size,
221 dram_base, image);
222 if (status != EFI_SUCCESS) {
223 efi_err("Failed to relocate kernel\n");
224 goto fail_free_screeninfo;
225 }
226
227 efi_retrieve_tpm2_eventlog();
228
229 /* Ask the firmware to clear memory on unclean shutdown */
230 efi_enable_reset_attack_mitigation();
231
232 secure_boot = efi_get_secureboot();
233
234 /*
235 * Unauthenticated device tree data is a security hazard, so ignore
236 * 'dtb=' unless UEFI Secure Boot is disabled. We assume that secure
237 * boot is enabled if we can't determine its state.
238 */
239 if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
240 secure_boot != efi_secureboot_mode_disabled) {
241 if (strstr(cmdline_ptr, "dtb="))
242 efi_err("Ignoring DTB from command line.\n");
243 } else {
244 status = efi_load_dtb(image, &fdt_addr, &fdt_size);
245
246 if (status != EFI_SUCCESS) {
247 efi_err("Failed to load device tree!\n");
248 goto fail_free_image;
249 }
250 }
251
252 if (fdt_addr) {
253 efi_info("Using DTB from command line\n");
254 } else {
255 /* Look for a device tree configuration table entry. */
256 fdt_addr = (uintptr_t)get_fdt(&fdt_size);
257 if (fdt_addr)
258 efi_info("Using DTB from configuration table\n");
259 }
260
261 if (!fdt_addr)
262 efi_info("Generating empty DTB\n");
263
264 if (!efi_noinitrd) {
265 max_addr = efi_get_max_initrd_addr(dram_base, image_addr);
266 status = efi_load_initrd(image, &initrd_addr, &initrd_size,
267 ULONG_MAX, max_addr);
268 if (status != EFI_SUCCESS)
269 efi_err("Failed to load initrd!\n");
270 }
271
272 efi_random_get_seed();
273
274 /*
275 * If the NX PE data feature is enabled in the properties table, we
276 * should take care not to create a virtual mapping that changes the
277 * relative placement of runtime services code and data regions, as
278 * they may belong to the same PE/COFF executable image in memory.
279 * The easiest way to achieve that is to simply use a 1:1 mapping.
280 */
281 prop_tbl = get_efi_config_table(EFI_PROPERTIES_TABLE_GUID);
282 flat_va_mapping = prop_tbl &&
283 (prop_tbl->memory_protection_attribute &
284 EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA);
285
286 /* hibernation expects the runtime regions to stay in the same place */
287 if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) {
288 /*
289 * Randomize the base of the UEFI runtime services region.
290 * Preserve the 2 MB alignment of the region by taking a
291 * shift of 21 bit positions into account when scaling
292 * the headroom value using a 32-bit random value.
293 */
294 static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
295 EFI_RT_VIRTUAL_BASE -
296 EFI_RT_VIRTUAL_SIZE;
297 u32 rnd;
298
299 status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd);
300 if (status == EFI_SUCCESS) {
301 virtmap_base = EFI_RT_VIRTUAL_BASE +
302 (((headroom >> 21) * rnd) >> (32 - 21));
303 }
304 }
305
306 install_memreserve_table();
307
308 status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr,
309 efi_get_max_fdt_addr(dram_base),
310 initrd_addr, initrd_size,
311 cmdline_ptr, fdt_addr, fdt_size);
312 if (status != EFI_SUCCESS)
313 goto fail_free_initrd;
314
315 if (IS_ENABLED(CONFIG_ARM))
316 efi_handle_post_ebs_state();
317
318 efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));
319 /* not reached */
320
321fail_free_initrd:
322 efi_err("Failed to update FDT and exit boot services\n");
323
324 efi_free(initrd_size, initrd_addr);
325 efi_free(fdt_size, fdt_addr);
326
327fail_free_image:
328 efi_free(image_size, image_addr);
329 efi_free(reserve_size, reserve_addr);
330fail_free_screeninfo:
331 free_screen_info(si);
332fail_free_cmdline:
333 efi_bs_call(free_pool, cmdline_ptr);
334fail:
335 return status;
336}
337
338/*
339 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
340 *
341 * This function populates the virt_addr fields of all memory region descriptors
342 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
343 * are also copied to @runtime_map, and their total count is returned in @count.
344 */
345void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
346 unsigned long desc_size, efi_memory_desc_t *runtime_map,
347 int *count)
348{
349 u64 efi_virt_base = virtmap_base;
350 efi_memory_desc_t *in, *out = runtime_map;
351 int l;
352
353 for (l = 0; l < map_size; l += desc_size) {
354 u64 paddr, size;
355
356 in = (void *)memory_map + l;
357 if (!(in->attribute & EFI_MEMORY_RUNTIME))
358 continue;
359
360 paddr = in->phys_addr;
361 size = in->num_pages * EFI_PAGE_SIZE;
362
363 in->virt_addr = in->phys_addr;
364 if (efi_novamap) {
365 continue;
366 }
367
368 /*
369 * Make the mapping compatible with 64k pages: this allows
370 * a 4k page size kernel to kexec a 64k page size kernel and
371 * vice versa.
372 */
373 if (!flat_va_mapping) {
374
375 paddr = round_down(in->phys_addr, SZ_64K);
376 size += in->phys_addr - paddr;
377
378 /*
379 * Avoid wasting memory on PTEs by choosing a virtual
380 * base that is compatible with section mappings if this
381 * region has the appropriate size and physical
382 * alignment. (Sections are 2 MB on 4k granule kernels)
383 */
384 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
385 efi_virt_base = round_up(efi_virt_base, SZ_2M);
386 else
387 efi_virt_base = round_up(efi_virt_base, SZ_64K);
388
389 in->virt_addr += efi_virt_base - paddr;
390 efi_virt_base += size;
391 }
392
393 memcpy(out, in, desc_size);
394 out = (void *)out + desc_size;
395 ++*count;
396 }
397}