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	arch_efi_call_virt(efi.runtime, f, args)
44
45union efi_rts_args {
46	struct {
47		efi_time_t 	*time;
48		efi_time_cap_t	*capabilities;
49	} GET_TIME;
50
51	struct {
52		efi_time_t	*time;
53	} SET_TIME;
54
55	struct {
56		efi_bool_t	*enabled;
57		efi_bool_t	*pending;
58		efi_time_t	*time;
59	} GET_WAKEUP_TIME;
60
61	struct {
62		efi_bool_t	enable;
63		efi_time_t	*time;
64	} SET_WAKEUP_TIME;
65
66	struct {
67		efi_char16_t	*name;
68		efi_guid_t	*vendor;
69		u32		*attr;
70		unsigned long	*data_size;
71		void		*data;
72	} GET_VARIABLE;
73
74	struct {
75		unsigned long	*name_size;
76		efi_char16_t	*name;
77		efi_guid_t 	*vendor;
78	} GET_NEXT_VARIABLE;
79
80	struct {
81		efi_char16_t	*name;
82		efi_guid_t	*vendor;
83		u32		attr;
84		unsigned long	data_size;
85		void		*data;
86	} SET_VARIABLE;
87
88	struct {
89		u32		attr;
90		u64		*storage_space;
91		u64		*remaining_space;
92		u64		*max_variable_size;
93	} QUERY_VARIABLE_INFO;
94
95	struct {
96		u32		*high_count;
97	} GET_NEXT_HIGH_MONO_COUNT;
98
99	struct {
100		efi_capsule_header_t **capsules;
101		unsigned long	count;
102		unsigned long	sg_list;
103	} UPDATE_CAPSULE;
104
105	struct {
106		efi_capsule_header_t **capsules;
107		unsigned long	count;
108		u64		*max_size;
109		int		*reset_type;
110	} QUERY_CAPSULE_CAPS;
111
112	struct {
113		efi_status_t	(__efiapi *acpi_prm_handler)(u64, void *);
114		u64		param_buffer_addr;
115		void		*context;
116	} ACPI_PRM_HANDLER;
117};
118
119struct efi_runtime_work efi_rts_work;
120
121/*
122 * efi_queue_work:	Queue EFI runtime service call and wait for completion
123 * @_rts:		EFI runtime service function identifier
124 * @_args:		Arguments to pass to the EFI runtime service
125 *
126 * Accesses to efi_runtime_services() are serialized by a binary
127 * semaphore (efi_runtime_lock) and caller waits until the work is
128 * finished, hence _only_ one work is queued at a time and the caller
129 * thread waits for completion.
130 */
131#define efi_queue_work(_rts, _args...)					\
132	__efi_queue_work(EFI_ ## _rts,					\
133			 &(union efi_rts_args){ ._rts = { _args }})
134
135#ifndef arch_efi_save_flags
136#define arch_efi_save_flags(state_flags)	local_save_flags(state_flags)
137#define arch_efi_restore_flags(state_flags)	local_irq_restore(state_flags)
138#endif
139
140unsigned long efi_call_virt_save_flags(void)
141{
142	unsigned long flags;
143
144	arch_efi_save_flags(flags);
145	return flags;
146}
147
148void efi_call_virt_check_flags(unsigned long flags, const void *caller)
149{
150	unsigned long cur_flags, mismatch;
151
152	cur_flags = efi_call_virt_save_flags();
153
154	mismatch = flags ^ cur_flags;
155	if (!WARN_ON_ONCE(mismatch & ARCH_EFI_IRQ_FLAGS_MASK))
156		return;
157
158	add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_NOW_UNRELIABLE);
159	pr_err_ratelimited(FW_BUG "IRQ flags corrupted (0x%08lx=>0x%08lx) by EFI call from %pS\n",
160			   flags, cur_flags, caller ?: __builtin_return_address(0));
161	arch_efi_restore_flags(flags);
162}
163
164/*
165 * According to section 7.1 of the UEFI spec, Runtime Services are not fully
166 * reentrant, and there are particular combinations of calls that need to be
167 * serialized. (source: UEFI Specification v2.4A)
168 *
169 * Table 31. Rules for Reentry Into Runtime Services
170 * +------------------------------------+-------------------------------+
171 * | If previous call is busy in	| Forbidden to call		|
172 * +------------------------------------+-------------------------------+
173 * | Any				| SetVirtualAddressMap()	|
174 * +------------------------------------+-------------------------------+
175 * | ConvertPointer()			| ConvertPointer()		|
176 * +------------------------------------+-------------------------------+
177 * | SetVariable()			| ResetSystem()			|
178 * | UpdateCapsule()			|				|
179 * | SetTime()				|				|
180 * | SetWakeupTime()			|				|
181 * | GetNextHighMonotonicCount()	|				|
182 * +------------------------------------+-------------------------------+
183 * | GetVariable()			| GetVariable()			|
184 * | GetNextVariableName()		| GetNextVariableName()		|
185 * | SetVariable()			| SetVariable()			|
186 * | QueryVariableInfo()		| QueryVariableInfo()		|
187 * | UpdateCapsule()			| UpdateCapsule()		|
188 * | QueryCapsuleCapabilities()		| QueryCapsuleCapabilities()	|
189 * | GetNextHighMonotonicCount()	| GetNextHighMonotonicCount()	|
190 * +------------------------------------+-------------------------------+
191 * | GetTime()				| GetTime()			|
192 * | SetTime()				| SetTime()			|
193 * | GetWakeupTime()			| GetWakeupTime()		|
194 * | SetWakeupTime()			| SetWakeupTime()		|
195 * +------------------------------------+-------------------------------+
196 *
197 * Due to the fact that the EFI pstore may write to the variable store in
198 * interrupt context, we need to use a lock for at least the groups that
199 * contain SetVariable() and QueryVariableInfo(). That leaves little else, as
200 * none of the remaining functions are actually ever called at runtime.
201 * So let's just use a single lock to serialize all Runtime Services calls.
202 */
203static DEFINE_SEMAPHORE(efi_runtime_lock, 1);
204
205/*
206 * Expose the EFI runtime lock to the UV platform
207 */
208#ifdef CONFIG_X86_UV
209extern struct semaphore __efi_uv_runtime_lock __alias(efi_runtime_lock);
210#endif
211
212/*
213 * Calls the appropriate efi_runtime_service() with the appropriate
214 * arguments.
215 */
216static void efi_call_rts(struct work_struct *work)
217{
218	const union efi_rts_args *args = efi_rts_work.args;
219	efi_status_t status = EFI_NOT_FOUND;
220	unsigned long flags;
221
222	arch_efi_call_virt_setup();
223	flags = efi_call_virt_save_flags();
224
225	switch (efi_rts_work.efi_rts_id) {
226	case EFI_GET_TIME:
227		status = efi_call_virt(get_time,
228				       args->GET_TIME.time,
229				       args->GET_TIME.capabilities);
230		break;
231	case EFI_SET_TIME:
232		status = efi_call_virt(set_time,
233				       args->SET_TIME.time);
234		break;
235	case EFI_GET_WAKEUP_TIME:
236		status = efi_call_virt(get_wakeup_time,
237				       args->GET_WAKEUP_TIME.enabled,
238				       args->GET_WAKEUP_TIME.pending,
239				       args->GET_WAKEUP_TIME.time);
240		break;
241	case EFI_SET_WAKEUP_TIME:
242		status = efi_call_virt(set_wakeup_time,
243				       args->SET_WAKEUP_TIME.enable,
244				       args->SET_WAKEUP_TIME.time);
245		break;
246	case EFI_GET_VARIABLE:
247		status = efi_call_virt(get_variable,
248				       args->GET_VARIABLE.name,
249				       args->GET_VARIABLE.vendor,
250				       args->GET_VARIABLE.attr,
251				       args->GET_VARIABLE.data_size,
252				       args->GET_VARIABLE.data);
253		break;
254	case EFI_GET_NEXT_VARIABLE:
255		status = efi_call_virt(get_next_variable,
256				       args->GET_NEXT_VARIABLE.name_size,
257				       args->GET_NEXT_VARIABLE.name,
258				       args->GET_NEXT_VARIABLE.vendor);
259		break;
260	case EFI_SET_VARIABLE:
261		status = efi_call_virt(set_variable,
262				       args->SET_VARIABLE.name,
263				       args->SET_VARIABLE.vendor,
264				       args->SET_VARIABLE.attr,
265				       args->SET_VARIABLE.data_size,
266				       args->SET_VARIABLE.data);
267		break;
268	case EFI_QUERY_VARIABLE_INFO:
269		status = efi_call_virt(query_variable_info,
270				       args->QUERY_VARIABLE_INFO.attr,
271				       args->QUERY_VARIABLE_INFO.storage_space,
272				       args->QUERY_VARIABLE_INFO.remaining_space,
273				       args->QUERY_VARIABLE_INFO.max_variable_size);
274		break;
275	case EFI_GET_NEXT_HIGH_MONO_COUNT:
276		status = efi_call_virt(get_next_high_mono_count,
277				       args->GET_NEXT_HIGH_MONO_COUNT.high_count);
278		break;
279	case EFI_UPDATE_CAPSULE:
280		status = efi_call_virt(update_capsule,
281				       args->UPDATE_CAPSULE.capsules,
282				       args->UPDATE_CAPSULE.count,
283				       args->UPDATE_CAPSULE.sg_list);
284		break;
285	case EFI_QUERY_CAPSULE_CAPS:
286		status = efi_call_virt(query_capsule_caps,
287				       args->QUERY_CAPSULE_CAPS.capsules,
288				       args->QUERY_CAPSULE_CAPS.count,
289				       args->QUERY_CAPSULE_CAPS.max_size,
290				       args->QUERY_CAPSULE_CAPS.reset_type);
291		break;
292	case EFI_ACPI_PRM_HANDLER:
293#ifdef CONFIG_ACPI_PRMT
294		status = arch_efi_call_virt(args, ACPI_PRM_HANDLER.acpi_prm_handler,
295					    args->ACPI_PRM_HANDLER.param_buffer_addr,
296					    args->ACPI_PRM_HANDLER.context);
297		break;
298#endif
299	default:
300		/*
301		 * Ideally, we should never reach here because a caller of this
302		 * function should have put the right efi_runtime_service()
303		 * function identifier into efi_rts_work->efi_rts_id
304		 */
305		pr_err("Requested executing invalid EFI Runtime Service.\n");
306	}
307
308	efi_call_virt_check_flags(flags, efi_rts_work.caller);
309	arch_efi_call_virt_teardown();
310
311	efi_rts_work.status = status;
312	complete(&efi_rts_work.efi_rts_comp);
313}
314
315static efi_status_t __efi_queue_work(enum efi_rts_ids id,
316				     union efi_rts_args *args)
317{
318	efi_rts_work.efi_rts_id = id;
319	efi_rts_work.args = args;
320	efi_rts_work.caller = __builtin_return_address(0);
321	efi_rts_work.status = EFI_ABORTED;
322
323	if (!efi_enabled(EFI_RUNTIME_SERVICES)) {
324		pr_warn_once("EFI Runtime Services are disabled!\n");
325		efi_rts_work.status = EFI_DEVICE_ERROR;
326		goto exit;
327	}
328
329	init_completion(&efi_rts_work.efi_rts_comp);
330	INIT_WORK(&efi_rts_work.work, efi_call_rts);
331
332	/*
333	 * queue_work() returns 0 if work was already on queue,
334	 * _ideally_ this should never happen.
335	 */
336	if (queue_work(efi_rts_wq, &efi_rts_work.work))
337		wait_for_completion(&efi_rts_work.efi_rts_comp);
338	else
339		pr_err("Failed to queue work to efi_rts_wq.\n");
340
341	WARN_ON_ONCE(efi_rts_work.status == EFI_ABORTED);
342exit:
343	efi_rts_work.efi_rts_id = EFI_NONE;
344	return efi_rts_work.status;
345}
346
347static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
348{
349	efi_status_t status;
350
351	if (down_interruptible(&efi_runtime_lock))
352		return EFI_ABORTED;
353	status = efi_queue_work(GET_TIME, tm, tc);
354	up(&efi_runtime_lock);
355	return status;
356}
357
358static efi_status_t virt_efi_set_time(efi_time_t *tm)
359{
360	efi_status_t status;
361
362	if (down_interruptible(&efi_runtime_lock))
363		return EFI_ABORTED;
364	status = efi_queue_work(SET_TIME, tm);
365	up(&efi_runtime_lock);
366	return status;
367}
368
369static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled,
370					     efi_bool_t *pending,
371					     efi_time_t *tm)
372{
373	efi_status_t status;
374
375	if (down_interruptible(&efi_runtime_lock))
376		return EFI_ABORTED;
377	status = efi_queue_work(GET_WAKEUP_TIME, enabled, pending, tm);
378	up(&efi_runtime_lock);
379	return status;
380}
381
382static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
383{
384	efi_status_t status;
385
386	if (down_interruptible(&efi_runtime_lock))
387		return EFI_ABORTED;
388	status = efi_queue_work(SET_WAKEUP_TIME, enabled, tm);
389	up(&efi_runtime_lock);
390	return status;
391}
392
393static efi_status_t virt_efi_get_variable(efi_char16_t *name,
394					  efi_guid_t *vendor,
395					  u32 *attr,
396					  unsigned long *data_size,
397					  void *data)
398{
399	efi_status_t status;
400
401	if (down_interruptible(&efi_runtime_lock))
402		return EFI_ABORTED;
403	status = efi_queue_work(GET_VARIABLE, name, vendor, attr, data_size,
404				data);
405	up(&efi_runtime_lock);
406	return status;
407}
408
409static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
410					       efi_char16_t *name,
411					       efi_guid_t *vendor)
412{
413	efi_status_t status;
414
415	if (down_interruptible(&efi_runtime_lock))
416		return EFI_ABORTED;
417	status = efi_queue_work(GET_NEXT_VARIABLE, name_size, name, vendor);
418	up(&efi_runtime_lock);
419	return status;
420}
421
422static efi_status_t virt_efi_set_variable(efi_char16_t *name,
423					  efi_guid_t *vendor,
424					  u32 attr,
425					  unsigned long data_size,
426					  void *data)
427{
428	efi_status_t status;
429
430	if (down_interruptible(&efi_runtime_lock))
431		return EFI_ABORTED;
432	status = efi_queue_work(SET_VARIABLE, name, vendor, attr, data_size,
433				data);
434	up(&efi_runtime_lock);
435	return status;
436}
437
438static efi_status_t
439virt_efi_set_variable_nb(efi_char16_t *name, efi_guid_t *vendor, u32 attr,
440			 unsigned long data_size, void *data)
441{
442	efi_status_t status;
443
444	if (down_trylock(&efi_runtime_lock))
445		return EFI_NOT_READY;
446
447	status = efi_call_virt_pointer(efi.runtime, set_variable, name, vendor,
448				       attr, data_size, data);
449	up(&efi_runtime_lock);
450	return status;
451}
452
453
454static efi_status_t virt_efi_query_variable_info(u32 attr,
455						 u64 *storage_space,
456						 u64 *remaining_space,
457						 u64 *max_variable_size)
458{
459	efi_status_t status;
460
461	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
462		return EFI_UNSUPPORTED;
463
464	if (down_interruptible(&efi_runtime_lock))
465		return EFI_ABORTED;
466	status = efi_queue_work(QUERY_VARIABLE_INFO, attr, storage_space,
467				remaining_space, max_variable_size);
468	up(&efi_runtime_lock);
469	return status;
470}
471
472static efi_status_t
473virt_efi_query_variable_info_nb(u32 attr, u64 *storage_space,
474				u64 *remaining_space, u64 *max_variable_size)
475{
476	efi_status_t status;
477
478	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
479		return EFI_UNSUPPORTED;
480
481	if (down_trylock(&efi_runtime_lock))
482		return EFI_NOT_READY;
483
484	status = efi_call_virt_pointer(efi.runtime, query_variable_info, attr,
485				       storage_space, remaining_space,
486				       max_variable_size);
487	up(&efi_runtime_lock);
488	return status;
489}
490
491static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
492{
493	efi_status_t status;
494
495	if (down_interruptible(&efi_runtime_lock))
496		return EFI_ABORTED;
497	status = efi_queue_work(GET_NEXT_HIGH_MONO_COUNT, count);
498	up(&efi_runtime_lock);
499	return status;
500}
501
502static void virt_efi_reset_system(int reset_type,
503				  efi_status_t status,
504				  unsigned long data_size,
505				  efi_char16_t *data)
506{
507	if (down_trylock(&efi_runtime_lock)) {
508		pr_warn("failed to invoke the reset_system() runtime service:\n"
509			"could not get exclusive access to the firmware\n");
510		return;
511	}
512
513	arch_efi_call_virt_setup();
514	efi_rts_work.efi_rts_id = EFI_RESET_SYSTEM;
515	arch_efi_call_virt(efi.runtime, reset_system, reset_type, status,
516			   data_size, data);
517	arch_efi_call_virt_teardown();
518
519	up(&efi_runtime_lock);
520}
521
522static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules,
523					    unsigned long count,
524					    unsigned long sg_list)
525{
526	efi_status_t status;
527
528	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
529		return EFI_UNSUPPORTED;
530
531	if (down_interruptible(&efi_runtime_lock))
532		return EFI_ABORTED;
533	status = efi_queue_work(UPDATE_CAPSULE, capsules, count, sg_list);
534	up(&efi_runtime_lock);
535	return status;
536}
537
538static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules,
539						unsigned long count,
540						u64 *max_size,
541						int *reset_type)
542{
543	efi_status_t status;
544
545	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
546		return EFI_UNSUPPORTED;
547
548	if (down_interruptible(&efi_runtime_lock))
549		return EFI_ABORTED;
550	status = efi_queue_work(QUERY_CAPSULE_CAPS, capsules, count,
551				max_size, reset_type);
552	up(&efi_runtime_lock);
553	return status;
554}
555
556void __init efi_native_runtime_setup(void)
557{
558	efi.get_time			    = virt_efi_get_time;
559	efi.set_time			    = virt_efi_set_time;
560	efi.get_wakeup_time		    = virt_efi_get_wakeup_time;
561	efi.set_wakeup_time		    = virt_efi_set_wakeup_time;
562	efi.get_variable		    = virt_efi_get_variable;
563	efi.get_next_variable		    = virt_efi_get_next_variable;
564	efi.set_variable		    = virt_efi_set_variable;
565	efi.set_variable_nonblocking	    = virt_efi_set_variable_nb;
566	efi.get_next_high_mono_count	    = virt_efi_get_next_high_mono_count;
567	efi.reset_system 		    = virt_efi_reset_system;
568	efi.query_variable_info		    = virt_efi_query_variable_info;
569	efi.query_variable_info_nonblocking = virt_efi_query_variable_info_nb;
570	efi.update_capsule		    = virt_efi_update_capsule;
571	efi.query_capsule_caps		    = virt_efi_query_capsule_caps;
572}
573
574#ifdef CONFIG_ACPI_PRMT
575
576efi_status_t
577efi_call_acpi_prm_handler(efi_status_t (__efiapi *handler_addr)(u64, void *),
578			  u64 param_buffer_addr, void *context)
579{
580	efi_status_t status;
581
582	if (down_interruptible(&efi_runtime_lock))
583		return EFI_ABORTED;
584	status = efi_queue_work(ACPI_PRM_HANDLER, handler_addr,
585				param_buffer_addr, context);
586	up(&efi_runtime_lock);
587	return status;
588}
589
590#endif
591