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/screen_info.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
40/*
41 * Some architectures map the EFI regions into the kernel's linear map using a
42 * fixed offset.
43 */
44#ifndef EFI_RT_VIRTUAL_OFFSET
45#define EFI_RT_VIRTUAL_OFFSET 0
46#endif
47
48static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
49static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0);
50
51void __weak free_screen_info(struct screen_info *si)
52{
53}
54
55static struct screen_info *setup_graphics(void)
56{
57 struct screen_info *si, tmp = {};
58
59 if (efi_setup_gop(si: &tmp) != EFI_SUCCESS)
60 return NULL;
61
62 si = alloc_screen_info();
63 if (!si)
64 return NULL;
65
66 *si = tmp;
67 return si;
68}
69
70static void install_memreserve_table(void)
71{
72 struct linux_efi_memreserve *rsv;
73 efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
74 efi_status_t status;
75
76 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
77 (void **)&rsv);
78 if (status != EFI_SUCCESS) {
79 efi_err("Failed to allocate memreserve entry!\n");
80 return;
81 }
82
83 rsv->next = 0;
84 rsv->size = 0;
85 atomic_set(v: &rsv->count, i: 0);
86
87 status = efi_bs_call(install_configuration_table,
88 &memreserve_table_guid, rsv);
89 if (status != EFI_SUCCESS)
90 efi_err("Failed to install memreserve config table!\n");
91}
92
93static u32 get_supported_rt_services(void)
94{
95 const efi_rt_properties_table_t *rt_prop_table;
96 u32 supported = EFI_RT_SUPPORTED_ALL;
97
98 rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID);
99 if (rt_prop_table)
100 supported &= rt_prop_table->runtime_services_supported;
101
102 return supported;
103}
104
105efi_status_t efi_handle_cmdline(efi_loaded_image_t *image, char **cmdline_ptr)
106{
107 char *cmdline __free(efi_pool) = NULL;
108 efi_status_t status;
109
110 /*
111 * Get the command line from EFI, using the LOADED_IMAGE
112 * protocol. We are going to copy the command line into the
113 * device tree, so this can be allocated anywhere.
114 */
115 cmdline = efi_convert_cmdline(image);
116 if (!cmdline) {
117 efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
118 return EFI_OUT_OF_RESOURCES;
119 }
120
121 if (!IS_ENABLED(CONFIG_CMDLINE_FORCE)) {
122 status = efi_parse_options(cmdline);
123 if (status != EFI_SUCCESS) {
124 efi_err("Failed to parse EFI load options\n");
125 return status;
126 }
127 }
128
129 if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
130 IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
131 cmdline[0] == 0) {
132 status = efi_parse_options(CONFIG_CMDLINE);
133 if (status != EFI_SUCCESS) {
134 efi_err("Failed to parse built-in command line\n");
135 return status;
136 }
137 }
138
139 *cmdline_ptr = no_free_ptr(cmdline);
140 return EFI_SUCCESS;
141}
142
143efi_status_t efi_stub_common(efi_handle_t handle,
144 efi_loaded_image_t *image,
145 unsigned long image_addr,
146 char *cmdline_ptr)
147{
148 struct screen_info *si;
149 efi_status_t status;
150
151 status = check_platform_features();
152 if (status != EFI_SUCCESS)
153 return status;
154
155 si = setup_graphics();
156
157 efi_retrieve_eventlog();
158
159 /* Ask the firmware to clear memory on unclean shutdown */
160 efi_enable_reset_attack_mitigation();
161
162 efi_load_initrd(image, ULONG_MAX, hard_limit: efi_get_max_initrd_addr(image_addr),
163 NULL);
164
165 efi_random_get_seed();
166
167 /* force efi_novamap if SetVirtualAddressMap() is unsupported */
168 efi_novamap |= !(get_supported_rt_services() &
169 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);
170
171 install_memreserve_table();
172
173 status = efi_boot_kernel(handle, image, kernel_addr: image_addr, cmdline_ptr);
174
175 free_screen_info(si);
176 return status;
177}
178
179/*
180 * efi_allocate_virtmap() - create a pool allocation for the virtmap
181 *
182 * Create an allocation that is of sufficient size to hold all the memory
183 * descriptors that will be passed to SetVirtualAddressMap() to inform the
184 * firmware about the virtual mapping that will be used under the OS to call
185 * into the firmware.
186 */
187efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap,
188 unsigned long *desc_size, u32 *desc_ver)
189{
190 unsigned long size, mmap_key;
191 efi_status_t status;
192
193 /*
194 * Use the size of the current memory map as an upper bound for the
195 * size of the buffer we need to pass to SetVirtualAddressMap() to
196 * cover all EFI_MEMORY_RUNTIME regions.
197 */
198 size = 0;
199 status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size,
200 desc_ver);
201 if (status != EFI_BUFFER_TOO_SMALL)
202 return EFI_LOAD_ERROR;
203
204 return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
205 (void **)virtmap);
206}
207
208/*
209 * efi_get_virtmap() - create a virtual mapping for the EFI memory map
210 *
211 * This function populates the virt_addr fields of all memory region descriptors
212 * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
213 * are also copied to @runtime_map, and their total count is returned in @count.
214 */
215void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
216 unsigned long desc_size, efi_memory_desc_t *runtime_map,
217 int *count)
218{
219 u64 efi_virt_base = virtmap_base;
220 efi_memory_desc_t *in, *out = runtime_map;
221 int l;
222
223 *count = 0;
224
225 for (l = 0; l < map_size; l += desc_size) {
226 u64 paddr, size;
227
228 in = (void *)memory_map + l;
229 if (!(in->attribute & EFI_MEMORY_RUNTIME))
230 continue;
231
232 paddr = in->phys_addr;
233 size = in->num_pages * EFI_PAGE_SIZE;
234
235 in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET;
236 if (efi_novamap) {
237 continue;
238 }
239
240 /*
241 * Make the mapping compatible with 64k pages: this allows
242 * a 4k page size kernel to kexec a 64k page size kernel and
243 * vice versa.
244 */
245 if (!flat_va_mapping) {
246
247 paddr = round_down(in->phys_addr, SZ_64K);
248 size += in->phys_addr - paddr;
249
250 /*
251 * Avoid wasting memory on PTEs by choosing a virtual
252 * base that is compatible with section mappings if this
253 * region has the appropriate size and physical
254 * alignment. (Sections are 2 MB on 4k granule kernels)
255 */
256 if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
257 efi_virt_base = round_up(efi_virt_base, SZ_2M);
258 else
259 efi_virt_base = round_up(efi_virt_base, SZ_64K);
260
261 in->virt_addr += efi_virt_base - paddr;
262 efi_virt_base += size;
263 }
264
265 memcpy(to: out, from: in, len: desc_size);
266 out = (void *)out + desc_size;
267 ++*count;
268 }
269}
270

source code of linux/drivers/firmware/efi/libstub/efi-stub.c