1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * runtime-wrappers.c - Runtime Services function call wrappers
4 *
5 * Implementation summary:
6 * -----------------------
7 * 1. When user/kernel thread requests to execute efi_runtime_service(),
8 * enqueue work to efi_rts_wq.
9 * 2. Caller thread waits for completion until the work is finished
10 * because it's dependent on the return status and execution of
11 * efi_runtime_service().
12 * For instance, get_variable() and get_next_variable().
13 *
14 * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
15 *
16 * Split off from arch/x86/platform/efi/efi.c
17 *
18 * Copyright (C) 1999 VA Linux Systems
19 * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
20 * Copyright (C) 1999-2002 Hewlett-Packard Co.
21 * Copyright (C) 2005-2008 Intel Co.
22 * Copyright (C) 2013 SuSE Labs
23 */
24
25#define pr_fmt(fmt)	"efi: " fmt
26
27#include <linux/bug.h>
28#include <linux/efi.h>
29#include <linux/irqflags.h>
30#include <linux/mutex.h>
31#include <linux/semaphore.h>
32#include <linux/stringify.h>
33#include <linux/workqueue.h>
34#include <linux/completion.h>
35
36#include <asm/efi.h>
37
38/*
39 * Wrap around the new efi_call_virt_generic() macros so that the
40 * code doesn't get too cluttered:
41 */
42#define efi_call_virt(f, args...)   \
43	efi_call_virt_pointer(efi.runtime, f, args)
44#define __efi_call_virt(f, args...) \
45	__efi_call_virt_pointer(efi.runtime, f, args)
46
47struct efi_runtime_work efi_rts_work;
48
49/*
50 * efi_queue_work:	Queue efi_runtime_service() and wait until it's done
51 * @rts:		efi_runtime_service() function identifier
52 * @rts_arg<1-5>:	efi_runtime_service() function arguments
53 *
54 * Accesses to efi_runtime_services() are serialized by a binary
55 * semaphore (efi_runtime_lock) and caller waits until the work is
56 * finished, hence _only_ one work is queued at a time and the caller
57 * thread waits for completion.
58 */
59#define efi_queue_work(_rts, _arg1, _arg2, _arg3, _arg4, _arg5)		\
60({									\
61	efi_rts_work.status = EFI_ABORTED;				\
62									\
63	if (!efi_enabled(EFI_RUNTIME_SERVICES)) {			\
64		pr_warn_once("EFI Runtime Services are disabled!\n");	\
65		efi_rts_work.status = EFI_DEVICE_ERROR;			\
66		goto exit;						\
67	}								\
68									\
69	init_completion(&efi_rts_work.efi_rts_comp);			\
70	INIT_WORK(&efi_rts_work.work, efi_call_rts);			\
71	efi_rts_work.arg1 = _arg1;					\
72	efi_rts_work.arg2 = _arg2;					\
73	efi_rts_work.arg3 = _arg3;					\
74	efi_rts_work.arg4 = _arg4;					\
75	efi_rts_work.arg5 = _arg5;					\
76	efi_rts_work.efi_rts_id = _rts;					\
77									\
78	/*								\
79	 * queue_work() returns 0 if work was already on queue,         \
80	 * _ideally_ this should never happen.                          \
81	 */								\
82	if (queue_work(efi_rts_wq, &efi_rts_work.work))			\
83		wait_for_completion(&efi_rts_work.efi_rts_comp);	\
84	else								\
85		pr_err("Failed to queue work to efi_rts_wq.\n");	\
86									\
87exit:									\
88	efi_rts_work.efi_rts_id = EFI_NONE;				\
89	efi_rts_work.status;						\
90})
91
92#ifndef arch_efi_save_flags
93#define arch_efi_save_flags(state_flags)	local_save_flags(state_flags)
94#define arch_efi_restore_flags(state_flags)	local_irq_restore(state_flags)
95#endif
96
97unsigned long efi_call_virt_save_flags(void)
98{
99	unsigned long flags;
100
101	arch_efi_save_flags(flags);
102	return flags;
103}
104
105void efi_call_virt_check_flags(unsigned long flags, const char *call)
106{
107	unsigned long cur_flags, mismatch;
108
109	cur_flags = efi_call_virt_save_flags();
110
111	mismatch = flags ^ cur_flags;
112	if (!WARN_ON_ONCE(mismatch & ARCH_EFI_IRQ_FLAGS_MASK))
113		return;
114
115	add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_NOW_UNRELIABLE);
116	pr_err_ratelimited(FW_BUG "IRQ flags corrupted (0x%08lx=>0x%08lx) by EFI %s\n",
117			   flags, cur_flags, call);
118	arch_efi_restore_flags(flags);
119}
120
121/*
122 * According to section 7.1 of the UEFI spec, Runtime Services are not fully
123 * reentrant, and there are particular combinations of calls that need to be
124 * serialized. (source: UEFI Specification v2.4A)
125 *
126 * Table 31. Rules for Reentry Into Runtime Services
127 * +------------------------------------+-------------------------------+
128 * | If previous call is busy in	| Forbidden to call		|
129 * +------------------------------------+-------------------------------+
130 * | Any				| SetVirtualAddressMap()	|
131 * +------------------------------------+-------------------------------+
132 * | ConvertPointer()			| ConvertPointer()		|
133 * +------------------------------------+-------------------------------+
134 * | SetVariable()			| ResetSystem()			|
135 * | UpdateCapsule()			|				|
136 * | SetTime()				|				|
137 * | SetWakeupTime()			|				|
138 * | GetNextHighMonotonicCount()	|				|
139 * +------------------------------------+-------------------------------+
140 * | GetVariable()			| GetVariable()			|
141 * | GetNextVariableName()		| GetNextVariableName()		|
142 * | SetVariable()			| SetVariable()			|
143 * | QueryVariableInfo()		| QueryVariableInfo()		|
144 * | UpdateCapsule()			| UpdateCapsule()		|
145 * | QueryCapsuleCapabilities()		| QueryCapsuleCapabilities()	|
146 * | GetNextHighMonotonicCount()	| GetNextHighMonotonicCount()	|
147 * +------------------------------------+-------------------------------+
148 * | GetTime()				| GetTime()			|
149 * | SetTime()				| SetTime()			|
150 * | GetWakeupTime()			| GetWakeupTime()		|
151 * | SetWakeupTime()			| SetWakeupTime()		|
152 * +------------------------------------+-------------------------------+
153 *
154 * Due to the fact that the EFI pstore may write to the variable store in
155 * interrupt context, we need to use a lock for at least the groups that
156 * contain SetVariable() and QueryVariableInfo(). That leaves little else, as
157 * none of the remaining functions are actually ever called at runtime.
158 * So let's just use a single lock to serialize all Runtime Services calls.
159 */
160static DEFINE_SEMAPHORE(efi_runtime_lock);
161
162/*
163 * Expose the EFI runtime lock to the UV platform
164 */
165#ifdef CONFIG_X86_UV
166extern struct semaphore __efi_uv_runtime_lock __alias(efi_runtime_lock);
167#endif
168
169/*
170 * Calls the appropriate efi_runtime_service() with the appropriate
171 * arguments.
172 *
173 * Semantics followed by efi_call_rts() to understand efi_runtime_work:
174 * 1. If argument was a pointer, recast it from void pointer to original
175 * pointer type.
176 * 2. If argument was a value, recast it from void pointer to original
177 * pointer type and dereference it.
178 */
179static void efi_call_rts(struct work_struct *work)
180{
181	void *arg1, *arg2, *arg3, *arg4, *arg5;
182	efi_status_t status = EFI_NOT_FOUND;
183
184	arg1 = efi_rts_work.arg1;
185	arg2 = efi_rts_work.arg2;
186	arg3 = efi_rts_work.arg3;
187	arg4 = efi_rts_work.arg4;
188	arg5 = efi_rts_work.arg5;
189
190	switch (efi_rts_work.efi_rts_id) {
191	case EFI_GET_TIME:
192		status = efi_call_virt(get_time, (efi_time_t *)arg1,
193				       (efi_time_cap_t *)arg2);
194		break;
195	case EFI_SET_TIME:
196		status = efi_call_virt(set_time, (efi_time_t *)arg1);
197		break;
198	case EFI_GET_WAKEUP_TIME:
199		status = efi_call_virt(get_wakeup_time, (efi_bool_t *)arg1,
200				       (efi_bool_t *)arg2, (efi_time_t *)arg3);
201		break;
202	case EFI_SET_WAKEUP_TIME:
203		status = efi_call_virt(set_wakeup_time, *(efi_bool_t *)arg1,
204				       (efi_time_t *)arg2);
205		break;
206	case EFI_GET_VARIABLE:
207		status = efi_call_virt(get_variable, (efi_char16_t *)arg1,
208				       (efi_guid_t *)arg2, (u32 *)arg3,
209				       (unsigned long *)arg4, (void *)arg5);
210		break;
211	case EFI_GET_NEXT_VARIABLE:
212		status = efi_call_virt(get_next_variable, (unsigned long *)arg1,
213				       (efi_char16_t *)arg2,
214				       (efi_guid_t *)arg3);
215		break;
216	case EFI_SET_VARIABLE:
217		status = efi_call_virt(set_variable, (efi_char16_t *)arg1,
218				       (efi_guid_t *)arg2, *(u32 *)arg3,
219				       *(unsigned long *)arg4, (void *)arg5);
220		break;
221	case EFI_QUERY_VARIABLE_INFO:
222		status = efi_call_virt(query_variable_info, *(u32 *)arg1,
223				       (u64 *)arg2, (u64 *)arg3, (u64 *)arg4);
224		break;
225	case EFI_GET_NEXT_HIGH_MONO_COUNT:
226		status = efi_call_virt(get_next_high_mono_count, (u32 *)arg1);
227		break;
228	case EFI_UPDATE_CAPSULE:
229		status = efi_call_virt(update_capsule,
230				       (efi_capsule_header_t **)arg1,
231				       *(unsigned long *)arg2,
232				       *(unsigned long *)arg3);
233		break;
234	case EFI_QUERY_CAPSULE_CAPS:
235		status = efi_call_virt(query_capsule_caps,
236				       (efi_capsule_header_t **)arg1,
237				       *(unsigned long *)arg2, (u64 *)arg3,
238				       (int *)arg4);
239		break;
240	default:
241		/*
242		 * Ideally, we should never reach here because a caller of this
243		 * function should have put the right efi_runtime_service()
244		 * function identifier into efi_rts_work->efi_rts_id
245		 */
246		pr_err("Requested executing invalid EFI Runtime Service.\n");
247	}
248	efi_rts_work.status = status;
249	complete(&efi_rts_work.efi_rts_comp);
250}
251
252static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
253{
254	efi_status_t status;
255
256	if (down_interruptible(&efi_runtime_lock))
257		return EFI_ABORTED;
258	status = efi_queue_work(EFI_GET_TIME, tm, tc, NULL, NULL, NULL);
259	up(&efi_runtime_lock);
260	return status;
261}
262
263static efi_status_t virt_efi_set_time(efi_time_t *tm)
264{
265	efi_status_t status;
266
267	if (down_interruptible(&efi_runtime_lock))
268		return EFI_ABORTED;
269	status = efi_queue_work(EFI_SET_TIME, tm, NULL, NULL, NULL, NULL);
270	up(&efi_runtime_lock);
271	return status;
272}
273
274static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled,
275					     efi_bool_t *pending,
276					     efi_time_t *tm)
277{
278	efi_status_t status;
279
280	if (down_interruptible(&efi_runtime_lock))
281		return EFI_ABORTED;
282	status = efi_queue_work(EFI_GET_WAKEUP_TIME, enabled, pending, tm, NULL,
283				NULL);
284	up(&efi_runtime_lock);
285	return status;
286}
287
288static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
289{
290	efi_status_t status;
291
292	if (down_interruptible(&efi_runtime_lock))
293		return EFI_ABORTED;
294	status = efi_queue_work(EFI_SET_WAKEUP_TIME, &enabled, tm, NULL, NULL,
295				NULL);
296	up(&efi_runtime_lock);
297	return status;
298}
299
300static efi_status_t virt_efi_get_variable(efi_char16_t *name,
301					  efi_guid_t *vendor,
302					  u32 *attr,
303					  unsigned long *data_size,
304					  void *data)
305{
306	efi_status_t status;
307
308	if (down_interruptible(&efi_runtime_lock))
309		return EFI_ABORTED;
310	status = efi_queue_work(EFI_GET_VARIABLE, name, vendor, attr, data_size,
311				data);
312	up(&efi_runtime_lock);
313	return status;
314}
315
316static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
317					       efi_char16_t *name,
318					       efi_guid_t *vendor)
319{
320	efi_status_t status;
321
322	if (down_interruptible(&efi_runtime_lock))
323		return EFI_ABORTED;
324	status = efi_queue_work(EFI_GET_NEXT_VARIABLE, name_size, name, vendor,
325				NULL, NULL);
326	up(&efi_runtime_lock);
327	return status;
328}
329
330static efi_status_t virt_efi_set_variable(efi_char16_t *name,
331					  efi_guid_t *vendor,
332					  u32 attr,
333					  unsigned long data_size,
334					  void *data)
335{
336	efi_status_t status;
337
338	if (down_interruptible(&efi_runtime_lock))
339		return EFI_ABORTED;
340	status = efi_queue_work(EFI_SET_VARIABLE, name, vendor, &attr, &data_size,
341				data);
342	up(&efi_runtime_lock);
343	return status;
344}
345
346static efi_status_t
347virt_efi_set_variable_nonblocking(efi_char16_t *name, efi_guid_t *vendor,
348				  u32 attr, unsigned long data_size,
349				  void *data)
350{
351	efi_status_t status;
352
353	if (down_trylock(&efi_runtime_lock))
354		return EFI_NOT_READY;
355
356	status = efi_call_virt(set_variable, name, vendor, attr, data_size,
357			       data);
358	up(&efi_runtime_lock);
359	return status;
360}
361
362
363static efi_status_t virt_efi_query_variable_info(u32 attr,
364						 u64 *storage_space,
365						 u64 *remaining_space,
366						 u64 *max_variable_size)
367{
368	efi_status_t status;
369
370	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
371		return EFI_UNSUPPORTED;
372
373	if (down_interruptible(&efi_runtime_lock))
374		return EFI_ABORTED;
375	status = efi_queue_work(EFI_QUERY_VARIABLE_INFO, &attr, storage_space,
376				remaining_space, max_variable_size, NULL);
377	up(&efi_runtime_lock);
378	return status;
379}
380
381static efi_status_t
382virt_efi_query_variable_info_nonblocking(u32 attr,
383					 u64 *storage_space,
384					 u64 *remaining_space,
385					 u64 *max_variable_size)
386{
387	efi_status_t status;
388
389	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
390		return EFI_UNSUPPORTED;
391
392	if (down_trylock(&efi_runtime_lock))
393		return EFI_NOT_READY;
394
395	status = efi_call_virt(query_variable_info, attr, storage_space,
396			       remaining_space, max_variable_size);
397	up(&efi_runtime_lock);
398	return status;
399}
400
401static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
402{
403	efi_status_t status;
404
405	if (down_interruptible(&efi_runtime_lock))
406		return EFI_ABORTED;
407	status = efi_queue_work(EFI_GET_NEXT_HIGH_MONO_COUNT, count, NULL, NULL,
408				NULL, NULL);
409	up(&efi_runtime_lock);
410	return status;
411}
412
413static void virt_efi_reset_system(int reset_type,
414				  efi_status_t status,
415				  unsigned long data_size,
416				  efi_char16_t *data)
417{
418	if (down_trylock(&efi_runtime_lock)) {
419		pr_warn("failed to invoke the reset_system() runtime service:\n"
420			"could not get exclusive access to the firmware\n");
421		return;
422	}
423	efi_rts_work.efi_rts_id = EFI_RESET_SYSTEM;
424	__efi_call_virt(reset_system, reset_type, status, data_size, data);
425	up(&efi_runtime_lock);
426}
427
428static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules,
429					    unsigned long count,
430					    unsigned long sg_list)
431{
432	efi_status_t status;
433
434	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
435		return EFI_UNSUPPORTED;
436
437	if (down_interruptible(&efi_runtime_lock))
438		return EFI_ABORTED;
439	status = efi_queue_work(EFI_UPDATE_CAPSULE, capsules, &count, &sg_list,
440				NULL, NULL);
441	up(&efi_runtime_lock);
442	return status;
443}
444
445static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules,
446						unsigned long count,
447						u64 *max_size,
448						int *reset_type)
449{
450	efi_status_t status;
451
452	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
453		return EFI_UNSUPPORTED;
454
455	if (down_interruptible(&efi_runtime_lock))
456		return EFI_ABORTED;
457	status = efi_queue_work(EFI_QUERY_CAPSULE_CAPS, capsules, &count,
458				max_size, reset_type, NULL);
459	up(&efi_runtime_lock);
460	return status;
461}
462
463void efi_native_runtime_setup(void)
464{
465	efi.get_time = virt_efi_get_time;
466	efi.set_time = virt_efi_set_time;
467	efi.get_wakeup_time = virt_efi_get_wakeup_time;
468	efi.set_wakeup_time = virt_efi_set_wakeup_time;
469	efi.get_variable = virt_efi_get_variable;
470	efi.get_next_variable = virt_efi_get_next_variable;
471	efi.set_variable = virt_efi_set_variable;
472	efi.set_variable_nonblocking = virt_efi_set_variable_nonblocking;
473	efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count;
474	efi.reset_system = virt_efi_reset_system;
475	efi.query_variable_info = virt_efi_query_variable_info;
476	efi.query_variable_info_nonblocking = virt_efi_query_variable_info_nonblocking;
477	efi.update_capsule = virt_efi_update_capsule;
478	efi.query_capsule_caps = virt_efi_query_capsule_caps;
479}
480