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
19static efi_char16_t efi_dummy_name[6] = { 'D', 'U', 'M', 'M', 'Y', 0 };
20
21static 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 */
37static int __init setup_storage_paranoia(char *arg)
38{
39	efi_no_storage_paranoia = true;
40	return 0;
41}
42early_param("efi_no_storage_paranoia", setup_storage_paranoia);
43
44/*
45 * Deleting the dummy variable which kicks off garbage collection
46*/
47void 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 */
63efi_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}
130EXPORT_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*/
141void __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
172void __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 */
204int __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
245out_memremap:
246	early_memunmap(data, sizeof(*data));
247out:
248	return ret;
249}
250
251void __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 */
278bool 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
287bool efi_poweroff_required(void)
288{
289	return !!acpi_gbl_reduced_hardware;
290}
291