summaryrefslogtreecommitdiff
path: root/drivers/firmware/efi/runtime-wrappers.c
blob: 228bbf91046137de619a4f8f89825e8ccc34b5ab (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
/*
 * runtime-wrappers.c - Runtime Services function call wrappers
 *
 * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
 *
 * Split off from arch/x86/platform/efi/efi.c
 *
 * Copyright (C) 1999 VA Linux Systems
 * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
 * Copyright (C) 1999-2002 Hewlett-Packard Co.
 * Copyright (C) 2005-2008 Intel Co.
 * Copyright (C) 2013 SuSE Labs
 *
 * This file is released under the GPLv2.
 */

#include <linux/bug.h>
#include <linux/efi.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <asm/efi.h>

/*
 * According to section 7.1 of the UEFI spec, Runtime Services are not fully
 * reentrant, and there are particular combinations of calls that need to be
 * serialized. (source: UEFI Specification v2.4A)
 *
 * Table 31. Rules for Reentry Into Runtime Services
 * +------------------------------------+-------------------------------+
 * | If previous call is busy in	| Forbidden to call		|
 * +------------------------------------+-------------------------------+
 * | Any				| SetVirtualAddressMap()	|
 * +------------------------------------+-------------------------------+
 * | ConvertPointer()			| ConvertPointer()		|
 * +------------------------------------+-------------------------------+
 * | SetVariable()			| ResetSystem()			|
 * | UpdateCapsule()			|				|
 * | SetTime()				|				|
 * | SetWakeupTime()			|				|
 * | GetNextHighMonotonicCount()	|				|
 * +------------------------------------+-------------------------------+
 * | GetVariable()			| GetVariable()			|
 * | GetNextVariableName()		| GetNextVariableName()		|
 * | SetVariable()			| SetVariable()			|
 * | QueryVariableInfo()		| QueryVariableInfo()		|
 * | UpdateCapsule()			| UpdateCapsule()		|
 * | QueryCapsuleCapabilities()		| QueryCapsuleCapabilities()	|
 * | GetNextHighMonotonicCount()	| GetNextHighMonotonicCount()	|
 * +------------------------------------+-------------------------------+
 * | GetTime()				| GetTime()			|
 * | SetTime()				| SetTime()			|
 * | GetWakeupTime()			| GetWakeupTime()		|
 * | SetWakeupTime()			| SetWakeupTime()		|
 * +------------------------------------+-------------------------------+
 *
 * Due to the fact that the EFI pstore may write to the variable store in
 * interrupt context, we need to use a spinlock for at least the groups that
 * contain SetVariable() and QueryVariableInfo(). That leaves little else, as
 * none of the remaining functions are actually ever called at runtime.
 * So let's just use a single spinlock to serialize all Runtime Services calls.
 */
static DEFINE_SPINLOCK(efi_runtime_lock);

/*
 * Some runtime services calls can be reentrant under NMI, even if the table
 * above says they are not. (source: UEFI Specification v2.4A)
 *
 * Table 32. Functions that may be called after Machine Check, INIT and NMI
 * +----------------------------+------------------------------------------+
 * | Function			| Called after Machine Check, INIT and NMI |
 * +----------------------------+------------------------------------------+
 * | GetTime()			| Yes, even if previously busy.		   |
 * | GetVariable()		| Yes, even if previously busy		   |
 * | GetNextVariableName()	| Yes, even if previously busy		   |
 * | QueryVariableInfo()	| Yes, even if previously busy		   |
 * | SetVariable()		| Yes, even if previously busy		   |
 * | UpdateCapsule()		| Yes, even if previously busy		   |
 * | QueryCapsuleCapabilities()	| Yes, even if previously busy		   |
 * | ResetSystem()		| Yes, even if previously busy		   |
 * +----------------------------+------------------------------------------+
 *
 * In order to prevent deadlocks under NMI, the wrappers for these functions
 * may only grab the efi_runtime_lock or rtc_lock spinlocks if !efi_in_nmi().
 * However, not all of the services listed are reachable through NMI code paths,
 * so the the special handling as suggested by the UEFI spec is only implemented
 * for QueryVariableInfo() and SetVariable(), as these can be reached in NMI
 * context through efi_pstore_write().
 */

/*
 * As per commit ef68c8f87ed1 ("x86: Serialize EFI time accesses on rtc_lock"),
 * the EFI specification requires that callers of the time related runtime
 * functions serialize with other CMOS accesses in the kernel, as the EFI time
 * functions may choose to also use the legacy CMOS RTC.
 */
__weak DEFINE_SPINLOCK(rtc_lock);

static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
{
	unsigned long flags;
	efi_status_t status;

	spin_lock_irqsave(&rtc_lock, flags);
	spin_lock(&efi_runtime_lock);
	status = efi_call_virt(get_time, tm, tc);
	spin_unlock(&efi_runtime_lock);
	spin_unlock_irqrestore(&rtc_lock, flags);
	return status;
}

static efi_status_t virt_efi_set_time(efi_time_t *tm)
{
	unsigned long flags;
	efi_status_t status;

	spin_lock_irqsave(&rtc_lock, flags);
	spin_lock(&efi_runtime_lock);
	status = efi_call_virt(set_time, tm);
	spin_unlock(&efi_runtime_lock);
	spin_unlock_irqrestore(&rtc_lock, flags);
	return status;
}

static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled,
					     efi_bool_t *pending,
					     efi_time_t *tm)
{
	unsigned long flags;
	efi_status_t status;

	spin_lock_irqsave(&rtc_lock, flags);
	spin_lock(&efi_runtime_lock);
	status = efi_call_virt(get_wakeup_time, enabled, pending, tm);
	spin_unlock(&efi_runtime_lock);
	spin_unlock_irqrestore(&rtc_lock, flags);
	return status;
}

static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
{
	unsigned long flags;
	efi_status_t status;

	spin_lock_irqsave(&rtc_lock, flags);
	spin_lock(&efi_runtime_lock);
	status = efi_call_virt(set_wakeup_time, enabled, tm);
	spin_unlock(&efi_runtime_lock);
	spin_unlock_irqrestore(&rtc_lock, flags);
	return status;
}

static efi_status_t virt_efi_get_variable(efi_char16_t *name,
					  efi_guid_t *vendor,
					  u32 *attr,
					  unsigned long *data_size,
					  void *data)
{
	unsigned long flags;
	efi_status_t status;

	spin_lock_irqsave(&efi_runtime_lock, flags);
	status = efi_call_virt(get_variable, name, vendor, attr, data_size,
			       data);
	spin_unlock_irqrestore(&efi_runtime_lock, flags);
	return status;
}

static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
					       efi_char16_t *name,
					       efi_guid_t *vendor)
{
	unsigned long flags;
	efi_status_t status;

	spin_lock_irqsave(&efi_runtime_lock, flags);
	status = efi_call_virt(get_next_variable, name_size, name, vendor);
	spin_unlock_irqrestore(&efi_runtime_lock, flags);
	return status;
}

static efi_status_t virt_efi_set_variable(efi_char16_t *name,
					  efi_guid_t *vendor,
					  u32 attr,
					  unsigned long data_size,
					  void *data)
{
	unsigned long flags;
	efi_status_t status;

	spin_lock_irqsave(&efi_runtime_lock, flags);
	status = efi_call_virt(set_variable, name, vendor, attr, data_size,
			       data);
	spin_unlock_irqrestore(&efi_runtime_lock, flags);
	return status;
}

static efi_status_t
virt_efi_set_variable_nonblocking(efi_char16_t *name, efi_guid_t *vendor,
				  u32 attr, unsigned long data_size,
				  void *data)
{
	unsigned long flags;
	efi_status_t status;

	if (!spin_trylock_irqsave(&efi_runtime_lock, flags))
		return EFI_NOT_READY;

	status = efi_call_virt(set_variable, name, vendor, attr, data_size,
			       data);
	spin_unlock_irqrestore(&efi_runtime_lock, flags);
	return status;
}


static efi_status_t virt_efi_query_variable_info(u32 attr,
						 u64 *storage_space,
						 u64 *remaining_space,
						 u64 *max_variable_size)
{
	unsigned long flags;
	efi_status_t status;

	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
		return EFI_UNSUPPORTED;

	spin_lock_irqsave(&efi_runtime_lock, flags);
	status = efi_call_virt(query_variable_info, attr, storage_space,
			       remaining_space, max_variable_size);
	spin_unlock_irqrestore(&efi_runtime_lock, flags);
	return status;
}

static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
{
	unsigned long flags;
	efi_status_t status;

	spin_lock_irqsave(&efi_runtime_lock, flags);
	status = efi_call_virt(get_next_high_mono_count, count);
	spin_unlock_irqrestore(&efi_runtime_lock, flags);
	return status;
}

static void virt_efi_reset_system(int reset_type,
				  efi_status_t status,
				  unsigned long data_size,
				  efi_char16_t *data)
{
	unsigned long flags;

	spin_lock_irqsave(&efi_runtime_lock, flags);
	__efi_call_virt(reset_system, reset_type, status, data_size, data);
	spin_unlock_irqrestore(&efi_runtime_lock, flags);
}

static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules,
					    unsigned long count,
					    unsigned long sg_list)
{
	unsigned long flags;
	efi_status_t status;

	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
		return EFI_UNSUPPORTED;

	spin_lock_irqsave(&efi_runtime_lock, flags);
	status = efi_call_virt(update_capsule, capsules, count, sg_list);
	spin_unlock_irqrestore(&efi_runtime_lock, flags);
	return status;
}

static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules,
						unsigned long count,
						u64 *max_size,
						int *reset_type)
{
	unsigned long flags;
	efi_status_t status;

	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
		return EFI_UNSUPPORTED;

	spin_lock_irqsave(&efi_runtime_lock, flags);
	status = efi_call_virt(query_capsule_caps, capsules, count, max_size,
			       reset_type);
	spin_unlock_irqrestore(&efi_runtime_lock, flags);
	return status;
}

void efi_native_runtime_setup(void)
{
	efi.get_time = virt_efi_get_time;
	efi.set_time = virt_efi_set_time;
	efi.get_wakeup_time = virt_efi_get_wakeup_time;
	efi.set_wakeup_time = virt_efi_set_wakeup_time;
	efi.get_variable = virt_efi_get_variable;
	efi.get_next_variable = virt_efi_get_next_variable;
	efi.set_variable = virt_efi_set_variable;
	efi.set_variable_nonblocking = virt_efi_set_variable_nonblocking;
	efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count;
	efi.reset_system = virt_efi_reset_system;
	efi.query_variable_info = virt_efi_query_variable_info;
	efi.update_capsule = virt_efi_update_capsule;
	efi.query_capsule_caps = virt_efi_query_capsule_caps;
}