summaryrefslogtreecommitdiffstats
path: root/drivers/firmware/efi/libstub/arm32-stub.c
blob: 7826553af2ba2c4c71c78f6522f8c497049e3f4f (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
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2013 Linaro Ltd;  <roy.franz@linaro.org>
 */
#include <linux/efi.h>
#include <asm/efi.h>

#include "efistub.h"

efi_status_t check_platform_features(void)
{
	int block;

	/* non-LPAE kernels can run anywhere */
	if (!IS_ENABLED(CONFIG_ARM_LPAE))
		return EFI_SUCCESS;

	/* LPAE kernels need compatible hardware */
	block = cpuid_feature_extract(CPUID_EXT_MMFR0, 0);
	if (block < 5) {
		pr_efi_err("This LPAE kernel is not supported by your CPU\n");
		return EFI_UNSUPPORTED;
	}
	return EFI_SUCCESS;
}

static efi_guid_t screen_info_guid = LINUX_EFI_ARM_SCREEN_INFO_TABLE_GUID;

struct screen_info *alloc_screen_info(void)
{
	struct screen_info *si;
	efi_status_t status;

	/*
	 * Unlike on arm64, where we can directly fill out the screen_info
	 * structure from the stub, we need to allocate a buffer to hold
	 * its contents while we hand over to the kernel proper from the
	 * decompressor.
	 */
	status = efi_bs_call(allocate_pool, EFI_RUNTIME_SERVICES_DATA,
			     sizeof(*si), (void **)&si);

	if (status != EFI_SUCCESS)
		return NULL;

	status = efi_bs_call(install_configuration_table,
			     &screen_info_guid, si);
	if (status == EFI_SUCCESS)
		return si;

	efi_bs_call(free_pool, si);
	return NULL;
}

void free_screen_info(struct screen_info *si)
{
	if (!si)
		return;

	efi_bs_call(install_configuration_table, &screen_info_guid, NULL);
	efi_bs_call(free_pool, si);
}

static efi_status_t reserve_kernel_base(unsigned long dram_base,
					unsigned long *reserve_addr,
					unsigned long *reserve_size)
{
	efi_physical_addr_t alloc_addr;
	efi_memory_desc_t *memory_map;
	unsigned long nr_pages, map_size, desc_size, buff_size;
	efi_status_t status;
	unsigned long l;

	struct efi_boot_memmap map = {
		.map		= &memory_map,
		.map_size	= &map_size,
		.desc_size	= &desc_size,
		.desc_ver	= NULL,
		.key_ptr	= NULL,
		.buff_size	= &buff_size,
	};

	/*
	 * Reserve memory for the uncompressed kernel image. This is
	 * all that prevents any future allocations from conflicting
	 * with the kernel. Since we can't tell from the compressed
	 * image how much DRAM the kernel actually uses (due to BSS
	 * size uncertainty) we allocate the maximum possible size.
	 * Do this very early, as prints can cause memory allocations
	 * that may conflict with this.
	 */
	alloc_addr = dram_base + MAX_UNCOMP_KERNEL_SIZE;
	nr_pages = MAX_UNCOMP_KERNEL_SIZE / EFI_PAGE_SIZE;
	status = efi_bs_call(allocate_pages, EFI_ALLOCATE_MAX_ADDRESS,
			     EFI_BOOT_SERVICES_DATA, nr_pages, &alloc_addr);
	if (status == EFI_SUCCESS) {
		if (alloc_addr == dram_base) {
			*reserve_addr = alloc_addr;
			*reserve_size = MAX_UNCOMP_KERNEL_SIZE;
			return EFI_SUCCESS;
		}
		/*
		 * If we end up here, the allocation succeeded but starts below
		 * dram_base. This can only occur if the real base of DRAM is
		 * not a multiple of 128 MB, in which case dram_base will have
		 * been rounded up. Since this implies that a part of the region
		 * was already occupied, we need to fall through to the code
		 * below to ensure that the existing allocations don't conflict.
		 * For this reason, we use EFI_BOOT_SERVICES_DATA above and not
		 * EFI_LOADER_DATA, which we wouldn't able to distinguish from
		 * allocations that we want to disallow.
		 */
	}

	/*
	 * If the allocation above failed, we may still be able to proceed:
	 * if the only allocations in the region are of types that will be
	 * released to the OS after ExitBootServices(), the decompressor can
	 * safely overwrite them.
	 */
	status = efi_get_memory_map(&map);
	if (status != EFI_SUCCESS) {
		pr_efi_err("reserve_kernel_base(): Unable to retrieve memory map.\n");
		return status;
	}

	for (l = 0; l < map_size; l += desc_size) {
		efi_memory_desc_t *desc;
		u64 start, end;

		desc = (void *)memory_map + l;
		start = desc->phys_addr;
		end = start + desc->num_pages * EFI_PAGE_SIZE;

		/* Skip if entry does not intersect with region */
		if (start >= dram_base + MAX_UNCOMP_KERNEL_SIZE ||
		    end <= dram_base)
			continue;

		switch (desc->type) {
		case EFI_BOOT_SERVICES_CODE:
		case EFI_BOOT_SERVICES_DATA:
			/* Ignore types that are released to the OS anyway */
			continue;

		case EFI_CONVENTIONAL_MEMORY:
			/* Skip soft reserved conventional memory */
			if (efi_soft_reserve_enabled() &&
			    (desc->attribute & EFI_MEMORY_SP))
				continue;

			/*
			 * Reserve the intersection between this entry and the
			 * region.
			 */
			start = max(start, (u64)dram_base);
			end = min(end, (u64)dram_base + MAX_UNCOMP_KERNEL_SIZE);

			status = efi_bs_call(allocate_pages,
					     EFI_ALLOCATE_ADDRESS,
					     EFI_LOADER_DATA,
					     (end - start) / EFI_PAGE_SIZE,
					     &start);
			if (status != EFI_SUCCESS) {
				pr_efi_err("reserve_kernel_base(): alloc failed.\n");
				goto out;
			}
			break;

		case EFI_LOADER_CODE:
		case EFI_LOADER_DATA:
			/*
			 * These regions may be released and reallocated for
			 * another purpose (including EFI_RUNTIME_SERVICE_DATA)
			 * at any time during the execution of the OS loader,
			 * so we cannot consider them as safe.
			 */
		default:
			/*
			 * Treat any other allocation in the region as unsafe */
			status = EFI_OUT_OF_RESOURCES;
			goto out;
		}
	}

	status = EFI_SUCCESS;
out:
	efi_bs_call(free_pool, memory_map);
	return status;
}

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)
{
	unsigned long kernel_base;
	efi_status_t status;

	/*
	 * Verify that the DRAM base address is compatible with the ARM
	 * boot protocol, which determines the base of DRAM by masking
	 * off the low 27 bits of the address at which the zImage is
	 * loaded. These assumptions are made by the decompressor,
	 * before any memory map is available.
	 */
	kernel_base = round_up(dram_base, SZ_128M);

	/*
	 * Note that some platforms (notably, the Raspberry Pi 2) put
	 * spin-tables and other pieces of firmware at the base of RAM,
	 * abusing the fact that the window of TEXT_OFFSET bytes at the
	 * base of the kernel image is only partially used at the moment.
	 * (Up to 5 pages are used for the swapper page tables)
	 */
	kernel_base += TEXT_OFFSET - 5 * PAGE_SIZE;

	status = reserve_kernel_base(kernel_base, reserve_addr, reserve_size);
	if (status != EFI_SUCCESS) {
		pr_efi_err("Unable to allocate memory for uncompressed kernel.\n");
		return status;
	}

	/*
	 * Relocate the zImage, so that it appears in the lowest 128 MB
	 * memory window.
	 */
	*image_addr = (unsigned long)image->image_base;
	*image_size = image->image_size;
	status = efi_relocate_kernel(image_addr, *image_size, *image_size,
				     kernel_base + MAX_UNCOMP_KERNEL_SIZE, 0, 0);
	if (status != EFI_SUCCESS) {
		pr_efi_err("Failed to relocate kernel.\n");
		efi_free(*reserve_size, *reserve_addr);
		*reserve_size = 0;
		return status;
	}

	/*
	 * Check to see if we were able to allocate memory low enough
	 * in memory. The kernel determines the base of DRAM from the
	 * address at which the zImage is loaded.
	 */
	if (*image_addr + *image_size > dram_base + ZIMAGE_OFFSET_LIMIT) {
		pr_efi_err("Failed to relocate kernel, no low memory available.\n");
		efi_free(*reserve_size, *reserve_addr);
		*reserve_size = 0;
		efi_free(*image_size, *image_addr);
		*image_size = 0;
		return EFI_LOAD_ERROR;
	}
	return EFI_SUCCESS;
}