runtime-wrappers.c

  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
205static struct task_struct *efi_runtime_lock_owner;
206
207/*
208 * Expose the EFI runtime lock to the UV platform
209 */
210#ifdef CONFIG_X86_UV
211extern struct semaphore __efi_uv_runtime_lock __alias(efi_runtime_lock);
212#endif
213
214/*
215 * Calls the appropriate efi_runtime_service() with the appropriate
216 * arguments.
217 */
218static void __nocfi efi_call_rts(struct work_struct *work)
219{
220	const union efi_rts_args *args = efi_rts_work.args;
221	efi_status_t status = EFI_NOT_FOUND;
222	unsigned long flags;
223
224	efi_runtime_lock_owner = current;
225
226	arch_efi_call_virt_setup();
227	flags = efi_call_virt_save_flags();
228
229	switch (efi_rts_work.efi_rts_id) {
230	case EFI_GET_TIME:
231		status = efi_call_virt(get_time,
232				       args->GET_TIME.time,
233				       args->GET_TIME.capabilities);
234		break;
235	case EFI_SET_TIME:
236		status = efi_call_virt(set_time,
237				       args->SET_TIME.time);
238		break;
239	case EFI_GET_WAKEUP_TIME:
240		status = efi_call_virt(get_wakeup_time,
241				       args->GET_WAKEUP_TIME.enabled,
242				       args->GET_WAKEUP_TIME.pending,
243				       args->GET_WAKEUP_TIME.time);
244		break;
245	case EFI_SET_WAKEUP_TIME:
246		status = efi_call_virt(set_wakeup_time,
247				       args->SET_WAKEUP_TIME.enable,
248				       args->SET_WAKEUP_TIME.time);
249		break;
250	case EFI_GET_VARIABLE:
251		status = efi_call_virt(get_variable,
252				       args->GET_VARIABLE.name,
253				       args->GET_VARIABLE.vendor,
254				       args->GET_VARIABLE.attr,
255				       args->GET_VARIABLE.data_size,
256				       args->GET_VARIABLE.data);
257		break;
258	case EFI_GET_NEXT_VARIABLE:
259		status = efi_call_virt(get_next_variable,
260				       args->GET_NEXT_VARIABLE.name_size,
261				       args->GET_NEXT_VARIABLE.name,
262				       args->GET_NEXT_VARIABLE.vendor);
263		break;
264	case EFI_SET_VARIABLE:
265		status = efi_call_virt(set_variable,
266				       args->SET_VARIABLE.name,
267				       args->SET_VARIABLE.vendor,
268				       args->SET_VARIABLE.attr,
269				       args->SET_VARIABLE.data_size,
270				       args->SET_VARIABLE.data);
271		break;
272	case EFI_QUERY_VARIABLE_INFO:
273		status = efi_call_virt(query_variable_info,
274				       args->QUERY_VARIABLE_INFO.attr,
275				       args->QUERY_VARIABLE_INFO.storage_space,
276				       args->QUERY_VARIABLE_INFO.remaining_space,
277				       args->QUERY_VARIABLE_INFO.max_variable_size);
278		break;
279	case EFI_GET_NEXT_HIGH_MONO_COUNT:
280		status = efi_call_virt(get_next_high_mono_count,
281				       args->GET_NEXT_HIGH_MONO_COUNT.high_count);
282		break;
283	case EFI_UPDATE_CAPSULE:
284		status = efi_call_virt(update_capsule,
285				       args->UPDATE_CAPSULE.capsules,
286				       args->UPDATE_CAPSULE.count,
287				       args->UPDATE_CAPSULE.sg_list);
288		break;
289	case EFI_QUERY_CAPSULE_CAPS:
290		status = efi_call_virt(query_capsule_caps,
291				       args->QUERY_CAPSULE_CAPS.capsules,
292				       args->QUERY_CAPSULE_CAPS.count,
293				       args->QUERY_CAPSULE_CAPS.max_size,
294				       args->QUERY_CAPSULE_CAPS.reset_type);
295		break;
296	case EFI_ACPI_PRM_HANDLER:
297#ifdef CONFIG_ACPI_PRMT
298		status = arch_efi_call_virt(args, ACPI_PRM_HANDLER.acpi_prm_handler,
299					    args->ACPI_PRM_HANDLER.param_buffer_addr,
300					    args->ACPI_PRM_HANDLER.context);
301		break;
302#endif
303	default:
304		/*
305		 * Ideally, we should never reach here because a caller of this
306		 * function should have put the right efi_runtime_service()
307		 * function identifier into efi_rts_work->efi_rts_id
308		 */
309		pr_err("Requested executing invalid EFI Runtime Service.\n");
310	}
311
312	efi_call_virt_check_flags(flags, efi_rts_work.caller);
313	arch_efi_call_virt_teardown();
314
315	efi_rts_work.status = status;
316	complete(&efi_rts_work.efi_rts_comp);
317	efi_runtime_lock_owner = NULL;
318}
319
320static efi_status_t __efi_queue_work(enum efi_rts_ids id,
321				     union efi_rts_args *args)
322{
323	efi_rts_work.efi_rts_id = id;
324	efi_rts_work.args = args;
325	efi_rts_work.caller = __builtin_return_address(0);
326	efi_rts_work.status = EFI_ABORTED;
327
328	if (!efi_enabled(EFI_RUNTIME_SERVICES)) {
329		pr_warn_once("EFI Runtime Services are disabled!\n");
330		efi_rts_work.status = EFI_DEVICE_ERROR;
331		goto exit;
332	}
333
334	init_completion(&efi_rts_work.efi_rts_comp);
335	INIT_WORK(&efi_rts_work.work, efi_call_rts);
336
337	/*
338	 * queue_work() returns 0 if work was already on queue,
339	 * _ideally_ this should never happen.
340	 */
341	if (queue_work(efi_rts_wq, &efi_rts_work.work))
342		wait_for_completion(&efi_rts_work.efi_rts_comp);
343	else
344		pr_err("Failed to queue work to efi_rts_wq.\n");
345
346	WARN_ON_ONCE(efi_rts_work.status == EFI_ABORTED);
347exit:
348	efi_rts_work.efi_rts_id = EFI_NONE;
349	return efi_rts_work.status;
350}
351
352static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
353{
354	efi_status_t status;
355
356	if (down_interruptible(&efi_runtime_lock))
357		return EFI_ABORTED;
358	status = efi_queue_work(GET_TIME, tm, tc);
359	up(&efi_runtime_lock);
360	return status;
361}
362
363static efi_status_t virt_efi_set_time(efi_time_t *tm)
364{
365	efi_status_t status;
366
367	if (down_interruptible(&efi_runtime_lock))
368		return EFI_ABORTED;
369	status = efi_queue_work(SET_TIME, tm);
370	up(&efi_runtime_lock);
371	return status;
372}
373
374static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled,
375					     efi_bool_t *pending,
376					     efi_time_t *tm)
377{
378	efi_status_t status;
379
380	if (down_interruptible(&efi_runtime_lock))
381		return EFI_ABORTED;
382	status = efi_queue_work(GET_WAKEUP_TIME, enabled, pending, tm);
383	up(&efi_runtime_lock);
384	return status;
385}
386
387static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
388{
389	efi_status_t status;
390
391	if (down_interruptible(&efi_runtime_lock))
392		return EFI_ABORTED;
393	status = efi_queue_work(SET_WAKEUP_TIME, enabled, tm);
394	up(&efi_runtime_lock);
395	return status;
396}
397
398static efi_status_t virt_efi_get_variable(efi_char16_t *name,
399					  efi_guid_t *vendor,
400					  u32 *attr,
401					  unsigned long *data_size,
402					  void *data)
403{
404	efi_status_t status;
405
406	if (down_interruptible(&efi_runtime_lock))
407		return EFI_ABORTED;
408	status = efi_queue_work(GET_VARIABLE, name, vendor, attr, data_size,
409				data);
410	up(&efi_runtime_lock);
411	return status;
412}
413
414static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
415					       efi_char16_t *name,
416					       efi_guid_t *vendor)
417{
418	efi_status_t status;
419
420	if (down_interruptible(&efi_runtime_lock))
421		return EFI_ABORTED;
422	status = efi_queue_work(GET_NEXT_VARIABLE, name_size, name, vendor);
423	up(&efi_runtime_lock);
424	return status;
425}
426
427static efi_status_t virt_efi_set_variable(efi_char16_t *name,
428					  efi_guid_t *vendor,
429					  u32 attr,
430					  unsigned long data_size,
431					  void *data)
432{
433	efi_status_t status;
434
435	if (down_interruptible(&efi_runtime_lock))
436		return EFI_ABORTED;
437	status = efi_queue_work(SET_VARIABLE, name, vendor, attr, data_size,
438				data);
439	up(&efi_runtime_lock);
440	return status;
441}
442
443static efi_status_t __nocfi
444virt_efi_set_variable_nb(efi_char16_t *name, efi_guid_t *vendor, u32 attr,
445			 unsigned long data_size, void *data)
446{
447	efi_status_t status;
448
449	if (down_trylock(&efi_runtime_lock))
450		return EFI_NOT_READY;
451
452	efi_runtime_lock_owner = current;
453	status = efi_call_virt_pointer(efi.runtime, set_variable, name, vendor,
454				       attr, data_size, data);
455	efi_runtime_lock_owner = NULL;
456	up(&efi_runtime_lock);
457	return status;
458}
459
460
461static efi_status_t virt_efi_query_variable_info(u32 attr,
462						 u64 *storage_space,
463						 u64 *remaining_space,
464						 u64 *max_variable_size)
465{
466	efi_status_t status;
467
468	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
469		return EFI_UNSUPPORTED;
470
471	if (down_interruptible(&efi_runtime_lock))
472		return EFI_ABORTED;
473	status = efi_queue_work(QUERY_VARIABLE_INFO, attr, storage_space,
474				remaining_space, max_variable_size);
475	up(&efi_runtime_lock);
476	return status;
477}
478
479static efi_status_t __nocfi
480virt_efi_query_variable_info_nb(u32 attr, u64 *storage_space,
481				u64 *remaining_space, u64 *max_variable_size)
482{
483	efi_status_t status;
484
485	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
486		return EFI_UNSUPPORTED;
487
488	if (down_trylock(&efi_runtime_lock))
489		return EFI_NOT_READY;
490
491	efi_runtime_lock_owner = current;
492	status = efi_call_virt_pointer(efi.runtime, query_variable_info, attr,
493				       storage_space, remaining_space,
494				       max_variable_size);
495	efi_runtime_lock_owner = NULL;
496	up(&efi_runtime_lock);
497	return status;
498}
499
500static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
501{
502	efi_status_t status;
503
504	if (down_interruptible(&efi_runtime_lock))
505		return EFI_ABORTED;
506	status = efi_queue_work(GET_NEXT_HIGH_MONO_COUNT, count);
507	up(&efi_runtime_lock);
508	return status;
509}
510
511static void __nocfi
512virt_efi_reset_system(int reset_type, efi_status_t status,
513		      unsigned long data_size, efi_char16_t *data)
514{
515	if (down_trylock(&efi_runtime_lock)) {
516		pr_warn("failed to invoke the reset_system() runtime service:\n"
517			"could not get exclusive access to the firmware\n");
518		return;
519	}
520
521	efi_runtime_lock_owner = current;
522	arch_efi_call_virt_setup();
523	efi_rts_work.efi_rts_id = EFI_RESET_SYSTEM;
524	arch_efi_call_virt(efi.runtime, reset_system, reset_type, status,
525			   data_size, data);
526	arch_efi_call_virt_teardown();
527	efi_runtime_lock_owner = NULL;
528	up(&efi_runtime_lock);
529}
530
531static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules,
532					    unsigned long count,
533					    unsigned long sg_list)
534{
535	efi_status_t status;
536
537	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
538		return EFI_UNSUPPORTED;
539
540	if (down_interruptible(&efi_runtime_lock))
541		return EFI_ABORTED;
542	status = efi_queue_work(UPDATE_CAPSULE, capsules, count, sg_list);
543	up(&efi_runtime_lock);
544	return status;
545}
546
547static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules,
548						unsigned long count,
549						u64 *max_size,
550						int *reset_type)
551{
552	efi_status_t status;
553
554	if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
555		return EFI_UNSUPPORTED;
556
557	if (down_interruptible(&efi_runtime_lock))
558		return EFI_ABORTED;
559	status = efi_queue_work(QUERY_CAPSULE_CAPS, capsules, count,
560				max_size, reset_type);
561	up(&efi_runtime_lock);
562	return status;
563}
564
565void __init efi_native_runtime_setup(void)
566{
567	efi.get_time			    = virt_efi_get_time;
568	efi.set_time			    = virt_efi_set_time;
569	efi.get_wakeup_time		    = virt_efi_get_wakeup_time;
570	efi.set_wakeup_time		    = virt_efi_set_wakeup_time;
571	efi.get_variable		    = virt_efi_get_variable;
572	efi.get_next_variable		    = virt_efi_get_next_variable;
573	efi.set_variable		    = virt_efi_set_variable;
574	efi.set_variable_nonblocking	    = virt_efi_set_variable_nb;
575	efi.get_next_high_mono_count	    = virt_efi_get_next_high_mono_count;
576	efi.reset_system 		    = virt_efi_reset_system;
577	efi.query_variable_info		    = virt_efi_query_variable_info;
578	efi.query_variable_info_nonblocking = virt_efi_query_variable_info_nb;
579	efi.update_capsule		    = virt_efi_update_capsule;
580	efi.query_capsule_caps		    = virt_efi_query_capsule_caps;
581}
582
583#ifdef CONFIG_ACPI_PRMT
584
585efi_status_t
586efi_call_acpi_prm_handler(efi_status_t (__efiapi *handler_addr)(u64, void *),
587			  u64 param_buffer_addr, void *context)
588{
589	efi_status_t status;
590
591	if (down_interruptible(&efi_runtime_lock))
592		return EFI_ABORTED;
593	status = efi_queue_work(ACPI_PRM_HANDLER, handler_addr,
594				param_buffer_addr, context);
595	up(&efi_runtime_lock);
596	return status;
597}
598
599#endif
600
601void efi_runtime_assert_lock_held(void)
602{
603	WARN_ON(efi_runtime_lock_owner != current);
604}