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/sort.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
38 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
39
efi_char16_printk(efi_system_table_t * sys_table_arg,efi_char16_t * str)40 void efi_char16_printk(efi_system_table_t *sys_table_arg,
41 efi_char16_t *str)
42 {
43 struct efi_simple_text_output_protocol *out;
44
45 out = (struct efi_simple_text_output_protocol *)sys_table_arg->con_out;
46 out->output_string(out, str);
47 }
48
setup_graphics(efi_system_table_t * sys_table_arg)49 static struct screen_info *setup_graphics(efi_system_table_t *sys_table_arg)
50 {
51 efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
52 efi_status_t status;
53 unsigned long size;
54 void **gop_handle = NULL;
55 struct screen_info *si = NULL;
56
57 size = 0;
58 status = efi_call_early(locate_handle, EFI_LOCATE_BY_PROTOCOL,
59 &gop_proto, NULL, &size, gop_handle);
60 if (status == EFI_BUFFER_TOO_SMALL) {
61 si = alloc_screen_info(sys_table_arg);
62 if (!si)
63 return NULL;
64 efi_setup_gop(sys_table_arg, si, &gop_proto, size);
65 }
66 return si;
67 }
68
install_memreserve_table(efi_system_table_t * sys_table_arg)69 void install_memreserve_table(efi_system_table_t *sys_table_arg)
70 {
71 struct linux_efi_memreserve *rsv;
72 efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
73 efi_status_t status;
74
75 status = efi_call_early(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
76 (void **)&rsv);
77 if (status != EFI_SUCCESS) {
78 pr_efi_err(sys_table_arg, "Failed to allocate memreserve entry!\n");
79 return;
80 }
81
82 rsv->next = 0;
83 rsv->size = 0;
84 atomic_set(&rsv->count, 0);
85
86 status = efi_call_early(install_configuration_table,
87 &memreserve_table_guid,
88 rsv);
89 if (status != EFI_SUCCESS)
90 pr_efi_err(sys_table_arg, "Failed to install memreserve config table!\n");
91 }
92
93
94 /*
95 * This function handles the architcture specific differences between arm and
96 * arm64 regarding where the kernel image must be loaded and any memory that
97 * must be reserved. On failure it is required to free all
98 * all allocations it has made.
99 */
100 efi_status_t handle_kernel_image(efi_system_table_t *sys_table,
101 unsigned long *image_addr,
102 unsigned long *image_size,
103 unsigned long *reserve_addr,
104 unsigned long *reserve_size,
105 unsigned long dram_base,
106 efi_loaded_image_t *image);
107 /*
108 * EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint
109 * that is described in the PE/COFF header. Most of the code is the same
110 * for both archictectures, with the arch-specific code provided in the
111 * handle_kernel_image() function.
112 */
efi_entry(void * handle,efi_system_table_t * sys_table,unsigned long * image_addr)113 unsigned long efi_entry(void *handle, efi_system_table_t *sys_table,
114 unsigned long *image_addr)
115 {
116 efi_loaded_image_t *image;
117 efi_status_t status;
118 unsigned long image_size = 0;
119 unsigned long dram_base;
120 /* addr/point and size pairs for memory management*/
121 unsigned long initrd_addr;
122 u64 initrd_size = 0;
123 unsigned long fdt_addr = 0; /* Original DTB */
124 unsigned long fdt_size = 0;
125 char *cmdline_ptr = NULL;
126 int cmdline_size = 0;
127 unsigned long new_fdt_addr;
128 efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
129 unsigned long reserve_addr = 0;
130 unsigned long reserve_size = 0;
131 enum efi_secureboot_mode secure_boot;
132 struct screen_info *si;
133
134 /* Check if we were booted by the EFI firmware */
135 if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
136 goto fail;
137
138 status = check_platform_features(sys_table);
139 if (status != EFI_SUCCESS)
140 goto fail;
141
142 /*
143 * Get a handle to the loaded image protocol. This is used to get
144 * information about the running image, such as size and the command
145 * line.
146 */
147 status = sys_table->boottime->handle_protocol(handle,
148 &loaded_image_proto, (void *)&image);
149 if (status != EFI_SUCCESS) {
150 pr_efi_err(sys_table, "Failed to get loaded image protocol\n");
151 goto fail;
152 }
153
154 dram_base = get_dram_base(sys_table);
155 if (dram_base == EFI_ERROR) {
156 pr_efi_err(sys_table, "Failed to find DRAM base\n");
157 goto fail;
158 }
159
160 /*
161 * Get the command line from EFI, using the LOADED_IMAGE
162 * protocol. We are going to copy the command line into the
163 * device tree, so this can be allocated anywhere.
164 */
165 cmdline_ptr = efi_convert_cmdline(sys_table, image, &cmdline_size);
166 if (!cmdline_ptr) {
167 pr_efi_err(sys_table, "getting command line via LOADED_IMAGE_PROTOCOL\n");
168 goto fail;
169 }
170
171 if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
172 IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
173 cmdline_size == 0)
174 efi_parse_options(CONFIG_CMDLINE);
175
176 if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0)
177 efi_parse_options(cmdline_ptr);
178
179 pr_efi(sys_table, "Booting Linux Kernel...\n");
180
181 si = setup_graphics(sys_table);
182
183 status = handle_kernel_image(sys_table, image_addr, &image_size,
184 &reserve_addr,
185 &reserve_size,
186 dram_base, image);
187 if (status != EFI_SUCCESS) {
188 pr_efi_err(sys_table, "Failed to relocate kernel\n");
189 goto fail_free_cmdline;
190 }
191
192 /* Ask the firmware to clear memory on unclean shutdown */
193 efi_enable_reset_attack_mitigation(sys_table);
194
195 secure_boot = efi_get_secureboot(sys_table);
196
197 /*
198 * Unauthenticated device tree data is a security hazard, so ignore
199 * 'dtb=' unless UEFI Secure Boot is disabled. We assume that secure
200 * boot is enabled if we can't determine its state.
201 */
202 if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
203 secure_boot != efi_secureboot_mode_disabled) {
204 if (strstr(cmdline_ptr, "dtb="))
205 pr_efi(sys_table, "Ignoring DTB from command line.\n");
206 } else {
207 status = handle_cmdline_files(sys_table, image, cmdline_ptr,
208 "dtb=",
209 ~0UL, &fdt_addr, &fdt_size);
210
211 if (status != EFI_SUCCESS) {
212 pr_efi_err(sys_table, "Failed to load device tree!\n");
213 goto fail_free_image;
214 }
215 }
216
217 if (fdt_addr) {
218 pr_efi(sys_table, "Using DTB from command line\n");
219 } else {
220 /* Look for a device tree configuration table entry. */
221 fdt_addr = (uintptr_t)get_fdt(sys_table, &fdt_size);
222 if (fdt_addr)
223 pr_efi(sys_table, "Using DTB from configuration table\n");
224 }
225
226 if (!fdt_addr)
227 pr_efi(sys_table, "Generating empty DTB\n");
228
229 status = handle_cmdline_files(sys_table, image, cmdline_ptr, "initrd=",
230 efi_get_max_initrd_addr(dram_base,
231 *image_addr),
232 (unsigned long *)&initrd_addr,
233 (unsigned long *)&initrd_size);
234 if (status != EFI_SUCCESS)
235 pr_efi_err(sys_table, "Failed initrd from command line!\n");
236
237 efi_random_get_seed(sys_table);
238
239 /* hibernation expects the runtime regions to stay in the same place */
240 if (!IS_ENABLED(CONFIG_HIBERNATION) && !nokaslr()) {
241 /*
242 * Randomize the base of the UEFI runtime services region.
243 * Preserve the 2 MB alignment of the region by taking a
244 * shift of 21 bit positions into account when scaling
245 * the headroom value using a 32-bit random value.
246 */
247 static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
248 EFI_RT_VIRTUAL_BASE -
249 EFI_RT_VIRTUAL_SIZE;
250 u32 rnd;
251
252 status = efi_get_random_bytes(sys_table, sizeof(rnd),
253 (u8 *)&rnd);
254 if (status == EFI_SUCCESS) {
255 virtmap_base = EFI_RT_VIRTUAL_BASE +
256 (((headroom >> 21) * rnd) >> (32 - 21));
257 }
258 }
259
260 install_memreserve_table(sys_table);
261
262 new_fdt_addr = fdt_addr;
263 status = allocate_new_fdt_and_exit_boot(sys_table, handle,
264 &new_fdt_addr, efi_get_max_fdt_addr(dram_base),
265 initrd_addr, initrd_size, cmdline_ptr,
266 fdt_addr, fdt_size);
267
268 /*
269 * If all went well, we need to return the FDT address to the
270 * calling function so it can be passed to kernel as part of
271 * the kernel boot protocol.
272 */
273 if (status == EFI_SUCCESS)
274 return new_fdt_addr;
275
276 pr_efi_err(sys_table, "Failed to update FDT and exit boot services\n");
277
278 efi_free(sys_table, initrd_size, initrd_addr);
279 efi_free(sys_table, fdt_size, fdt_addr);
280
281 fail_free_image:
282 efi_free(sys_table, image_size, *image_addr);
283 efi_free(sys_table, reserve_size, reserve_addr);
284 fail_free_cmdline:
285 free_screen_info(sys_table, si);
286 efi_free(sys_table, cmdline_size, (unsigned long)cmdline_ptr);
287 fail:
288 return EFI_ERROR;
289 }
290
cmp_mem_desc(const void * l,const void * r)291 static int cmp_mem_desc(const void *l, const void *r)
292 {
293 const efi_memory_desc_t *left = l, *right = r;
294
295 return (left->phys_addr > right->phys_addr) ? 1 : -1;
296 }
297
298 /*
299 * Returns whether region @left ends exactly where region @right starts,
300 * or false if either argument is NULL.
301 */
regions_are_adjacent(efi_memory_desc_t * left,efi_memory_desc_t * right)302 static bool regions_are_adjacent(efi_memory_desc_t *left,
303 efi_memory_desc_t *right)
304 {
305 u64 left_end;
306
307 if (left == NULL || right == NULL)
308 return false;
309
310 left_end = left->phys_addr + left->num_pages * EFI_PAGE_SIZE;
311
312 return left_end == right->phys_addr;
313 }
314
315 /*
316 * Returns whether region @left and region @right have compatible memory type
317 * mapping attributes, and are both EFI_MEMORY_RUNTIME regions.
318 */
regions_have_compatible_memory_type_attrs(efi_memory_desc_t * left,efi_memory_desc_t * right)319 static bool regions_have_compatible_memory_type_attrs(efi_memory_desc_t *left,
320 efi_memory_desc_t *right)
321 {
322 static const u64 mem_type_mask = EFI_MEMORY_WB | EFI_MEMORY_WT |
323 EFI_MEMORY_WC | EFI_MEMORY_UC |
324 EFI_MEMORY_RUNTIME;
325
326 return ((left->attribute ^ right->attribute) & mem_type_mask) == 0;
327 }
328
329 /*
330 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
331 *
332 * This function populates the virt_addr fields of all memory region descriptors
333 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
334 * are also copied to @runtime_map, and their total count is returned in @count.
335 */
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)336 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
337 unsigned long desc_size, efi_memory_desc_t *runtime_map,
338 int *count)
339 {
340 u64 efi_virt_base = virtmap_base;
341 efi_memory_desc_t *in, *prev = NULL, *out = runtime_map;
342 int l;
343
344 /*
345 * To work around potential issues with the Properties Table feature
346 * introduced in UEFI 2.5, which may split PE/COFF executable images
347 * in memory into several RuntimeServicesCode and RuntimeServicesData
348 * regions, we need to preserve the relative offsets between adjacent
349 * EFI_MEMORY_RUNTIME regions with the same memory type attributes.
350 * The easiest way to find adjacent regions is to sort the memory map
351 * before traversing it.
352 */
353 if (IS_ENABLED(CONFIG_ARM64))
354 sort(memory_map, map_size / desc_size, desc_size, cmp_mem_desc,
355 NULL);
356
357 for (l = 0; l < map_size; l += desc_size, prev = in) {
358 u64 paddr, size;
359
360 in = (void *)memory_map + l;
361 if (!(in->attribute & EFI_MEMORY_RUNTIME))
362 continue;
363
364 paddr = in->phys_addr;
365 size = in->num_pages * EFI_PAGE_SIZE;
366
367 if (novamap()) {
368 in->virt_addr = in->phys_addr;
369 continue;
370 }
371
372 /*
373 * Make the mapping compatible with 64k pages: this allows
374 * a 4k page size kernel to kexec a 64k page size kernel and
375 * vice versa.
376 */
377 if ((IS_ENABLED(CONFIG_ARM64) &&
378 !regions_are_adjacent(prev, in)) ||
379 !regions_have_compatible_memory_type_attrs(prev, in)) {
380
381 paddr = round_down(in->phys_addr, SZ_64K);
382 size += in->phys_addr - paddr;
383
384 /*
385 * Avoid wasting memory on PTEs by choosing a virtual
386 * base that is compatible with section mappings if this
387 * region has the appropriate size and physical
388 * alignment. (Sections are 2 MB on 4k granule kernels)
389 */
390 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
391 efi_virt_base = round_up(efi_virt_base, SZ_2M);
392 else
393 efi_virt_base = round_up(efi_virt_base, SZ_64K);
394 }
395
396 in->virt_addr = efi_virt_base + in->phys_addr - paddr;
397 efi_virt_base += size;
398
399 memcpy(out, in, desc_size);
400 out = (void *)out + desc_size;
401 ++*count;
402 }
403 }
404
