1 #include <linux/init.h>
2 #include <linux/kernel.h>
3 #include <linux/string.h>
4 #include <linux/time.h>
5 #include <linux/types.h>
6 #include <linux/efi.h>
7 #include <linux/slab.h>
8 #include <linux/memblock.h>
9 #include <linux/bootmem.h>
10 #include <linux/acpi.h>
11 #include <asm/efi.h>
12 #include <asm/uv/uv.h>
13
14 #define EFI_MIN_RESERVE 5120
15
16 #define EFI_DUMMY_GUID \
17 EFI_GUID(0x4424ac57, 0xbe4b, 0x47dd, 0x9e, 0x97, 0xed, 0x50, 0xf0, 0x9f, 0x92, 0xa9)
18
19 static efi_char16_t efi_dummy_name[6] = { 'D', 'U', 'M', 'M', 'Y', 0 };
20
21 static bool efi_no_storage_paranoia;
22
23 /*
24 * Some firmware implementations refuse to boot if there's insufficient
25 * space in the variable store. The implementation of garbage collection
26 * in some FW versions causes stale (deleted) variables to take up space
27 * longer than intended and space is only freed once the store becomes
28 * almost completely full.
29 *
30 * Enabling this option disables the space checks in
31 * efi_query_variable_store() and forces garbage collection.
32 *
33 * Only enable this option if deleting EFI variables does not free up
34 * space in your variable store, e.g. if despite deleting variables
35 * you're unable to create new ones.
36 */
setup_storage_paranoia(char * arg)37 static int __init setup_storage_paranoia(char *arg)
38 {
39 efi_no_storage_paranoia = true;
40 return 0;
41 }
42 early_param("efi_no_storage_paranoia", setup_storage_paranoia);
43
44 /*
45 * Deleting the dummy variable which kicks off garbage collection
46 */
efi_delete_dummy_variable(void)47 void efi_delete_dummy_variable(void)
48 {
49 efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
50 EFI_VARIABLE_NON_VOLATILE |
51 EFI_VARIABLE_BOOTSERVICE_ACCESS |
52 EFI_VARIABLE_RUNTIME_ACCESS,
53 0, NULL);
54 }
55
56 /*
57 * Some firmware implementations refuse to boot if there's insufficient space
58 * in the variable store. Ensure that we never use more than a safe limit.
59 *
60 * Return EFI_SUCCESS if it is safe to write 'size' bytes to the variable
61 * store.
62 */
efi_query_variable_store(u32 attributes,unsigned long size)63 efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
64 {
65 efi_status_t status;
66 u64 storage_size, remaining_size, max_size;
67
68 if (!(attributes & EFI_VARIABLE_NON_VOLATILE))
69 return 0;
70
71 status = efi.query_variable_info(attributes, &storage_size,
72 &remaining_size, &max_size);
73 if (status != EFI_SUCCESS)
74 return status;
75
76 /*
77 * We account for that by refusing the write if permitting it would
78 * reduce the available space to under 5KB. This figure was provided by
79 * Samsung, so should be safe.
80 */
81 if ((remaining_size - size < EFI_MIN_RESERVE) &&
82 !efi_no_storage_paranoia) {
83
84 /*
85 * Triggering garbage collection may require that the firmware
86 * generate a real EFI_OUT_OF_RESOURCES error. We can force
87 * that by attempting to use more space than is available.
88 */
89 unsigned long dummy_size = remaining_size + 1024;
90 void *dummy = kzalloc(dummy_size, GFP_ATOMIC);
91
92 if (!dummy)
93 return EFI_OUT_OF_RESOURCES;
94
95 status = efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
96 EFI_VARIABLE_NON_VOLATILE |
97 EFI_VARIABLE_BOOTSERVICE_ACCESS |
98 EFI_VARIABLE_RUNTIME_ACCESS,
99 dummy_size, dummy);
100
101 if (status == EFI_SUCCESS) {
102 /*
103 * This should have failed, so if it didn't make sure
104 * that we delete it...
105 */
106 efi_delete_dummy_variable();
107 }
108
109 kfree(dummy);
110
111 /*
112 * The runtime code may now have triggered a garbage collection
113 * run, so check the variable info again
114 */
115 status = efi.query_variable_info(attributes, &storage_size,
116 &remaining_size, &max_size);
117
118 if (status != EFI_SUCCESS)
119 return status;
120
121 /*
122 * There still isn't enough room, so return an error
123 */
124 if (remaining_size - size < EFI_MIN_RESERVE)
125 return EFI_OUT_OF_RESOURCES;
126 }
127
128 return EFI_SUCCESS;
129 }
130 EXPORT_SYMBOL_GPL(efi_query_variable_store);
131
132 /*
133 * The UEFI specification makes it clear that the operating system is free to do
134 * whatever it wants with boot services code after ExitBootServices() has been
135 * called. Ignoring this recommendation a significant bunch of EFI implementations
136 * continue calling into boot services code (SetVirtualAddressMap). In order to
137 * work around such buggy implementations we reserve boot services region during
138 * EFI init and make sure it stays executable. Then, after SetVirtualAddressMap(), it
139 * is discarded.
140 */
efi_reserve_boot_services(void)141 void __init efi_reserve_boot_services(void)
142 {
143 void *p;
144
145 for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
146 efi_memory_desc_t *md = p;
147 u64 start = md->phys_addr;
148 u64 size = md->num_pages << EFI_PAGE_SHIFT;
149
150 if (md->type != EFI_BOOT_SERVICES_CODE &&
151 md->type != EFI_BOOT_SERVICES_DATA)
152 continue;
153 /* Only reserve where possible:
154 * - Not within any already allocated areas
155 * - Not over any memory area (really needed, if above?)
156 * - Not within any part of the kernel
157 * - Not the bios reserved area
158 */
159 if ((start + size > __pa_symbol(_text)
160 && start <= __pa_symbol(_end)) ||
161 !e820_all_mapped(start, start+size, E820_RAM) ||
162 memblock_is_region_reserved(start, size)) {
163 /* Could not reserve, skip it */
164 md->num_pages = 0;
165 memblock_dbg("Could not reserve boot range [0x%010llx-0x%010llx]\n",
166 start, start+size-1);
167 } else
168 memblock_reserve(start, size);
169 }
170 }
171
efi_free_boot_services(void)172 void __init efi_free_boot_services(void)
173 {
174 void *p;
175
176 for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
177 efi_memory_desc_t *md = p;
178 unsigned long long start = md->phys_addr;
179 unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
180
181 if (md->type != EFI_BOOT_SERVICES_CODE &&
182 md->type != EFI_BOOT_SERVICES_DATA)
183 continue;
184
185 /* Could not reserve boot area */
186 if (!size)
187 continue;
188
189 free_bootmem_late(start, size);
190 }
191
192 efi_unmap_memmap();
193 }
194
195 /*
196 * A number of config table entries get remapped to virtual addresses
197 * after entering EFI virtual mode. However, the kexec kernel requires
198 * their physical addresses therefore we pass them via setup_data and
199 * correct those entries to their respective physical addresses here.
200 *
201 * Currently only handles smbios which is necessary for some firmware
202 * implementation.
203 */
efi_reuse_config(u64 tables,int nr_tables)204 int __init efi_reuse_config(u64 tables, int nr_tables)
205 {
206 int i, sz, ret = 0;
207 void *p, *tablep;
208 struct efi_setup_data *data;
209
210 if (!efi_setup)
211 return 0;
212
213 if (!efi_enabled(EFI_64BIT))
214 return 0;
215
216 data = early_memremap(efi_setup, sizeof(*data));
217 if (!data) {
218 ret = -ENOMEM;
219 goto out;
220 }
221
222 if (!data->smbios)
223 goto out_memremap;
224
225 sz = sizeof(efi_config_table_64_t);
226
227 p = tablep = early_memremap(tables, nr_tables * sz);
228 if (!p) {
229 pr_err("Could not map Configuration table!\n");
230 ret = -ENOMEM;
231 goto out_memremap;
232 }
233
234 for (i = 0; i < efi.systab->nr_tables; i++) {
235 efi_guid_t guid;
236
237 guid = ((efi_config_table_64_t *)p)->guid;
238
239 if (!efi_guidcmp(guid, SMBIOS_TABLE_GUID))
240 ((efi_config_table_64_t *)p)->table = data->smbios;
241 p += sz;
242 }
243 early_memunmap(tablep, nr_tables * sz);
244
245 out_memremap:
246 early_memunmap(data, sizeof(*data));
247 out:
248 return ret;
249 }
250
efi_apply_memmap_quirks(void)251 void __init efi_apply_memmap_quirks(void)
252 {
253 /*
254 * Once setup is done earlier, unmap the EFI memory map on mismatched
255 * firmware/kernel architectures since there is no support for runtime
256 * services.
257 */
258 if (!efi_runtime_supported()) {
259 pr_info("efi: Setup done, disabling due to 32/64-bit mismatch\n");
260 efi_unmap_memmap();
261 }
262
263 /*
264 * UV doesn't support the new EFI pagetable mapping yet.
265 */
266 if (is_uv_system())
267 set_bit(EFI_OLD_MEMMAP, &efi.flags);
268 }
269
270 /*
271 * For most modern platforms the preferred method of powering off is via
272 * ACPI. However, there are some that are known to require the use of
273 * EFI runtime services and for which ACPI does not work at all.
274 *
275 * Using EFI is a last resort, to be used only if no other option
276 * exists.
277 */
efi_reboot_required(void)278 bool efi_reboot_required(void)
279 {
280 if (!acpi_gbl_reduced_hardware)
281 return false;
282
283 efi_reboot_quirk_mode = EFI_RESET_WARM;
284 return true;
285 }
286
efi_poweroff_required(void)287 bool efi_poweroff_required(void)
288 {
289 return !!acpi_gbl_reduced_hardware;
290 }
291