aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/firmware/efi/libstub/arm-stub.c
blob: 7bbef4a6735048977b616a9f018d8d04fdcf5951 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
// SPDX-License-Identifier: GPL-2.0-only
/*
 * EFI stub implementation that is shared by arm and arm64 architectures.
 * This should be #included by the EFI stub implementation files.
 *
 * Copyright (C) 2013,2014 Linaro Limited
 *     Roy Franz <roy.franz@linaro.org
 * Copyright (C) 2013 Red Hat, Inc.
 *     Mark Salter <msalter@redhat.com>
 */

#include <linux/efi.h>
#include <linux/sort.h>
#include <asm/efi.h>

#include "efistub.h"

/*
 * This is the base address at which to start allocating virtual memory ranges
 * for UEFI Runtime Services. This is in the low TTBR0 range so that we can use
 * any allocation we choose, and eliminate the risk of a conflict after kexec.
 * The value chosen is the largest non-zero power of 2 suitable for this purpose
 * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
 * be mapped efficiently.
 * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
 * map everything below 1 GB. (512 MB is a reasonable upper bound for the
 * entire footprint of the UEFI runtime services memory regions)
 */
#define EFI_RT_VIRTUAL_BASE	SZ_512M
#define EFI_RT_VIRTUAL_SIZE	SZ_512M

#ifdef CONFIG_ARM64
# define EFI_RT_VIRTUAL_LIMIT	DEFAULT_MAP_WINDOW_64
#else
# define EFI_RT_VIRTUAL_LIMIT	TASK_SIZE
#endif

static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;

static efi_system_table_t *__efistub_global sys_table;

__pure efi_system_table_t *efi_system_table(void)
{
	return sys_table;
}

static struct screen_info *setup_graphics(void)
{
	efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
	efi_status_t status;
	unsigned long size;
	void **gop_handle = NULL;
	struct screen_info *si = NULL;

	size = 0;
	status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
			     &gop_proto, NULL, &size, gop_handle);
	if (status == EFI_BUFFER_TOO_SMALL) {
		si = alloc_screen_info();
		if (!si)
			return NULL;
		efi_setup_gop(si, &gop_proto, size);
	}
	return si;
}

void install_memreserve_table(void)
{
	struct linux_efi_memreserve *rsv;
	efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
	efi_status_t status;

	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
			     (void **)&rsv);
	if (status != EFI_SUCCESS) {
		pr_efi_err("Failed to allocate memreserve entry!\n");
		return;
	}

	rsv->next = 0;
	rsv->size = 0;
	atomic_set(&rsv->count, 0);

	status = efi_bs_call(install_configuration_table,
			     &memreserve_table_guid, rsv);
	if (status != EFI_SUCCESS)
		pr_efi_err("Failed to install memreserve config table!\n");
}


/*
 * This function handles the architcture specific differences between arm and
 * arm64 regarding where the kernel image must be loaded and any memory that
 * must be reserved. On failure it is required to free all
 * all allocations it has made.
 */
efi_status_t handle_kernel_image(unsigned long *image_addr,
				 unsigned long *image_size,
				 unsigned long *reserve_addr,
				 unsigned long *reserve_size,
				 unsigned long dram_base,
				 efi_loaded_image_t *image);
/*
 * EFI entry point for the arm/arm64 EFI stubs.  This is the entrypoint
 * that is described in the PE/COFF header.  Most of the code is the same
 * for both archictectures, with the arch-specific code provided in the
 * handle_kernel_image() function.
 */
unsigned long efi_entry(void *handle, efi_system_table_t *sys_table_arg,
			       unsigned long *image_addr)
{
	efi_loaded_image_t *image;
	efi_status_t status;
	unsigned long image_size = 0;
	unsigned long dram_base;
	/* addr/point and size pairs for memory management*/
	unsigned long initrd_addr;
	u64 initrd_size = 0;
	unsigned long fdt_addr = 0;  /* Original DTB */
	unsigned long fdt_size = 0;
	char *cmdline_ptr = NULL;
	int cmdline_size = 0;
	unsigned long new_fdt_addr;
	efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;
	unsigned long reserve_addr = 0;
	unsigned long reserve_size = 0;
	enum efi_secureboot_mode secure_boot;
	struct screen_info *si;

	sys_table = sys_table_arg;

	/* Check if we were booted by the EFI firmware */
	if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
		goto fail;

	status = check_platform_features();
	if (status != EFI_SUCCESS)
		goto fail;

	/*
	 * Get a handle to the loaded image protocol.  This is used to get
	 * information about the running image, such as size and the command
	 * line.
	 */
	status = sys_table->boottime->handle_protocol(handle,
					&loaded_image_proto, (void *)&image);
	if (status != EFI_SUCCESS) {
		pr_efi_err("Failed to get loaded image protocol\n");
		goto fail;
	}

	dram_base = get_dram_base();
	if (dram_base == EFI_ERROR) {
		pr_efi_err("Failed to find DRAM base\n");
		goto fail;
	}

	/*
	 * Get the command line from EFI, using the LOADED_IMAGE
	 * protocol. We are going to copy the command line into the
	 * device tree, so this can be allocated anywhere.
	 */
	cmdline_ptr = efi_convert_cmdline(image, &cmdline_size);
	if (!cmdline_ptr) {
		pr_efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
		goto fail;
	}

	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
	    cmdline_size == 0)
		efi_parse_options(CONFIG_CMDLINE);

	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0)
		efi_parse_options(cmdline_ptr);

	pr_efi("Booting Linux Kernel...\n");

	si = setup_graphics();

	status = handle_kernel_image(image_addr, &image_size,
				     &reserve_addr,
				     &reserve_size,
				     dram_base, image);
	if (status != EFI_SUCCESS) {
		pr_efi_err("Failed to relocate kernel\n");
		goto fail_free_cmdline;
	}

	efi_retrieve_tpm2_eventlog();

	/* Ask the firmware to clear memory on unclean shutdown */
	efi_enable_reset_attack_mitigation();

	secure_boot = efi_get_secureboot();

	/*
	 * Unauthenticated device tree data is a security hazard, so ignore
	 * 'dtb=' unless UEFI Secure Boot is disabled.  We assume that secure
	 * boot is enabled if we can't determine its state.
	 */
	if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||
	     secure_boot != efi_secureboot_mode_disabled) {
		if (strstr(cmdline_ptr, "dtb="))
			pr_efi("Ignoring DTB from command line.\n");
	} else {
		status = handle_cmdline_files(image, cmdline_ptr, "dtb=",
					      ~0UL, &fdt_addr, &fdt_size);

		if (status != EFI_SUCCESS) {
			pr_efi_err("Failed to load device tree!\n");
			goto fail_free_image;
		}
	}

	if (fdt_addr) {
		pr_efi("Using DTB from command line\n");
	} else {
		/* Look for a device tree configuration table entry. */
		fdt_addr = (uintptr_t)get_fdt(&fdt_size);
		if (fdt_addr)
			pr_efi("Using DTB from configuration table\n");
	}

	if (!fdt_addr)
		pr_efi("Generating empty DTB\n");

	status = handle_cmdline_files(image, cmdline_ptr, "initrd=",
				      efi_get_max_initrd_addr(dram_base,
							      *image_addr),
				      (unsigned long *)&initrd_addr,
				      (unsigned long *)&initrd_size);
	if (status != EFI_SUCCESS)
		pr_efi_err("Failed initrd from command line!\n");

	efi_random_get_seed();

	/* hibernation expects the runtime regions to stay in the same place */
	if (!IS_ENABLED(CONFIG_HIBERNATION) && !nokaslr()) {
		/*
		 * Randomize the base of the UEFI runtime services region.
		 * Preserve the 2 MB alignment of the region by taking a
		 * shift of 21 bit positions into account when scaling
		 * the headroom value using a 32-bit random value.
		 */
		static const u64 headroom = EFI_RT_VIRTUAL_LIMIT -
					    EFI_RT_VIRTUAL_BASE -
					    EFI_RT_VIRTUAL_SIZE;
		u32 rnd;

		status = efi_get_random_bytes(sizeof(rnd), (u8 *)&rnd);
		if (status == EFI_SUCCESS) {
			virtmap_base = EFI_RT_VIRTUAL_BASE +
				       (((headroom >> 21) * rnd) >> (32 - 21));
		}
	}

	install_memreserve_table();

	new_fdt_addr = fdt_addr;
	status = allocate_new_fdt_and_exit_boot(handle,
				&new_fdt_addr, efi_get_max_fdt_addr(dram_base),
				initrd_addr, initrd_size, cmdline_ptr,
				fdt_addr, fdt_size);

	/*
	 * If all went well, we need to return the FDT address to the
	 * calling function so it can be passed to kernel as part of
	 * the kernel boot protocol.
	 */
	if (status == EFI_SUCCESS)
		return new_fdt_addr;

	pr_efi_err("Failed to update FDT and exit boot services\n");

	efi_free(initrd_size, initrd_addr);
	efi_free(fdt_size, fdt_addr);

fail_free_image:
	efi_free(image_size, *image_addr);
	efi_free(reserve_size, reserve_addr);
fail_free_cmdline:
	free_screen_info(si);
	efi_free(cmdline_size, (unsigned long)cmdline_ptr);
fail:
	return EFI_ERROR;
}

static int cmp_mem_desc(const void *l, const void *r)
{
	const efi_memory_desc_t *left = l, *right = r;

	return (left->phys_addr > right->phys_addr) ? 1 : -1;
}

/*
 * Returns whether region @left ends exactly where region @right starts,
 * or false if either argument is NULL.
 */
static bool regions_are_adjacent(efi_memory_desc_t *left,
				 efi_memory_desc_t *right)
{
	u64 left_end;

	if (left == NULL || right == NULL)
		return false;

	left_end = left->phys_addr + left->num_pages * EFI_PAGE_SIZE;

	return left_end == right->phys_addr;
}

/*
 * Returns whether region @left and region @right have compatible memory type
 * mapping attributes, and are both EFI_MEMORY_RUNTIME regions.
 */
static bool regions_have_compatible_memory_type_attrs(efi_memory_desc_t *left,
						      efi_memory_desc_t *right)
{
	static const u64 mem_type_mask = EFI_MEMORY_WB | EFI_MEMORY_WT |
					 EFI_MEMORY_WC | EFI_MEMORY_UC |
					 EFI_MEMORY_RUNTIME;

	return ((left->attribute ^ right->attribute) & mem_type_mask) == 0;
}

/*
 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
 *
 * This function populates the virt_addr fields of all memory region descriptors
 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
 * are also copied to @runtime_map, and their total count is returned in @count.
 */
void 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)
{
	u64 efi_virt_base = virtmap_base;
	efi_memory_desc_t *in, *prev = NULL, *out = runtime_map;
	int l;

	/*
	 * To work around potential issues with the Properties Table feature
	 * introduced in UEFI 2.5, which may split PE/COFF executable images
	 * in memory into several RuntimeServicesCode and RuntimeServicesData
	 * regions, we need to preserve the relative offsets between adjacent
	 * EFI_MEMORY_RUNTIME regions with the same memory type attributes.
	 * The easiest way to find adjacent regions is to sort the memory map
	 * before traversing it.
	 */
	if (IS_ENABLED(CONFIG_ARM64))
		sort(memory_map, map_size / desc_size, desc_size, cmp_mem_desc,
		     NULL);

	for (l = 0; l < map_size; l += desc_size, prev = in) {
		u64 paddr, size;

		in = (void *)memory_map + l;
		if (!(in->attribute & EFI_MEMORY_RUNTIME))
			continue;

		paddr = in->phys_addr;
		size = in->num_pages * EFI_PAGE_SIZE;

		if (novamap()) {
			in->virt_addr = in->phys_addr;
			continue;
		}

		/*
		 * Make the mapping compatible with 64k pages: this allows
		 * a 4k page size kernel to kexec a 64k page size kernel and
		 * vice versa.
		 */
		if ((IS_ENABLED(CONFIG_ARM64) &&
		     !regions_are_adjacent(prev, in)) ||
		    !regions_have_compatible_memory_type_attrs(prev, in)) {

			paddr = round_down(in->phys_addr, SZ_64K);
			size += in->phys_addr - paddr;

			/*
			 * Avoid wasting memory on PTEs by choosing a virtual
			 * base that is compatible with section mappings if this
			 * region has the appropriate size and physical
			 * alignment. (Sections are 2 MB on 4k granule kernels)
			 */
			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
				efi_virt_base = round_up(efi_virt_base, SZ_2M);
			else
				efi_virt_base = round_up(efi_virt_base, SZ_64K);
		}

		in->virt_addr = efi_virt_base + in->phys_addr - paddr;
		efi_virt_base += size;

		memcpy(out, in, desc_size);
		out = (void *)out + desc_size;
		++*count;
	}
}