xref: /openbmc/linux/kernel/power/hibernate.c (revision 5d0e4d78)
1 /*
2  * kernel/power/hibernate.c - Hibernation (a.k.a suspend-to-disk) support.
3  *
4  * Copyright (c) 2003 Patrick Mochel
5  * Copyright (c) 2003 Open Source Development Lab
6  * Copyright (c) 2004 Pavel Machek <pavel@ucw.cz>
7  * Copyright (c) 2009 Rafael J. Wysocki, Novell Inc.
8  * Copyright (C) 2012 Bojan Smojver <bojan@rexursive.com>
9  *
10  * This file is released under the GPLv2.
11  */
12 
13 #define pr_fmt(fmt) "PM: " fmt
14 
15 #include <linux/export.h>
16 #include <linux/suspend.h>
17 #include <linux/syscalls.h>
18 #include <linux/reboot.h>
19 #include <linux/string.h>
20 #include <linux/device.h>
21 #include <linux/async.h>
22 #include <linux/delay.h>
23 #include <linux/fs.h>
24 #include <linux/mount.h>
25 #include <linux/pm.h>
26 #include <linux/nmi.h>
27 #include <linux/console.h>
28 #include <linux/cpu.h>
29 #include <linux/freezer.h>
30 #include <linux/gfp.h>
31 #include <linux/syscore_ops.h>
32 #include <linux/ctype.h>
33 #include <linux/genhd.h>
34 #include <linux/ktime.h>
35 #include <trace/events/power.h>
36 
37 #include "power.h"
38 
39 
40 static int nocompress;
41 static int noresume;
42 static int nohibernate;
43 static int resume_wait;
44 static unsigned int resume_delay;
45 static char resume_file[256] = CONFIG_PM_STD_PARTITION;
46 dev_t swsusp_resume_device;
47 sector_t swsusp_resume_block;
48 __visible int in_suspend __nosavedata;
49 
50 enum {
51 	HIBERNATION_INVALID,
52 	HIBERNATION_PLATFORM,
53 	HIBERNATION_SHUTDOWN,
54 	HIBERNATION_REBOOT,
55 #ifdef CONFIG_SUSPEND
56 	HIBERNATION_SUSPEND,
57 #endif
58 	HIBERNATION_TEST_RESUME,
59 	/* keep last */
60 	__HIBERNATION_AFTER_LAST
61 };
62 #define HIBERNATION_MAX (__HIBERNATION_AFTER_LAST-1)
63 #define HIBERNATION_FIRST (HIBERNATION_INVALID + 1)
64 
65 static int hibernation_mode = HIBERNATION_SHUTDOWN;
66 
67 bool freezer_test_done;
68 
69 static const struct platform_hibernation_ops *hibernation_ops;
70 
71 bool hibernation_available(void)
72 {
73 	return (nohibernate == 0);
74 }
75 
76 /**
77  * hibernation_set_ops - Set the global hibernate operations.
78  * @ops: Hibernation operations to use in subsequent hibernation transitions.
79  */
80 void hibernation_set_ops(const struct platform_hibernation_ops *ops)
81 {
82 	if (ops && !(ops->begin && ops->end &&  ops->pre_snapshot
83 	    && ops->prepare && ops->finish && ops->enter && ops->pre_restore
84 	    && ops->restore_cleanup && ops->leave)) {
85 		WARN_ON(1);
86 		return;
87 	}
88 	lock_system_sleep();
89 	hibernation_ops = ops;
90 	if (ops)
91 		hibernation_mode = HIBERNATION_PLATFORM;
92 	else if (hibernation_mode == HIBERNATION_PLATFORM)
93 		hibernation_mode = HIBERNATION_SHUTDOWN;
94 
95 	unlock_system_sleep();
96 }
97 EXPORT_SYMBOL_GPL(hibernation_set_ops);
98 
99 static bool entering_platform_hibernation;
100 
101 bool system_entering_hibernation(void)
102 {
103 	return entering_platform_hibernation;
104 }
105 EXPORT_SYMBOL(system_entering_hibernation);
106 
107 #ifdef CONFIG_PM_DEBUG
108 static void hibernation_debug_sleep(void)
109 {
110 	pr_info("hibernation debug: Waiting for 5 seconds.\n");
111 	mdelay(5000);
112 }
113 
114 static int hibernation_test(int level)
115 {
116 	if (pm_test_level == level) {
117 		hibernation_debug_sleep();
118 		return 1;
119 	}
120 	return 0;
121 }
122 #else /* !CONFIG_PM_DEBUG */
123 static int hibernation_test(int level) { return 0; }
124 #endif /* !CONFIG_PM_DEBUG */
125 
126 /**
127  * platform_begin - Call platform to start hibernation.
128  * @platform_mode: Whether or not to use the platform driver.
129  */
130 static int platform_begin(int platform_mode)
131 {
132 	return (platform_mode && hibernation_ops) ?
133 		hibernation_ops->begin() : 0;
134 }
135 
136 /**
137  * platform_end - Call platform to finish transition to the working state.
138  * @platform_mode: Whether or not to use the platform driver.
139  */
140 static void platform_end(int platform_mode)
141 {
142 	if (platform_mode && hibernation_ops)
143 		hibernation_ops->end();
144 }
145 
146 /**
147  * platform_pre_snapshot - Call platform to prepare the machine for hibernation.
148  * @platform_mode: Whether or not to use the platform driver.
149  *
150  * Use the platform driver to prepare the system for creating a hibernate image,
151  * if so configured, and return an error code if that fails.
152  */
153 
154 static int platform_pre_snapshot(int platform_mode)
155 {
156 	return (platform_mode && hibernation_ops) ?
157 		hibernation_ops->pre_snapshot() : 0;
158 }
159 
160 /**
161  * platform_leave - Call platform to prepare a transition to the working state.
162  * @platform_mode: Whether or not to use the platform driver.
163  *
164  * Use the platform driver prepare to prepare the machine for switching to the
165  * normal mode of operation.
166  *
167  * This routine is called on one CPU with interrupts disabled.
168  */
169 static void platform_leave(int platform_mode)
170 {
171 	if (platform_mode && hibernation_ops)
172 		hibernation_ops->leave();
173 }
174 
175 /**
176  * platform_finish - Call platform to switch the system to the working state.
177  * @platform_mode: Whether or not to use the platform driver.
178  *
179  * Use the platform driver to switch the machine to the normal mode of
180  * operation.
181  *
182  * This routine must be called after platform_prepare().
183  */
184 static void platform_finish(int platform_mode)
185 {
186 	if (platform_mode && hibernation_ops)
187 		hibernation_ops->finish();
188 }
189 
190 /**
191  * platform_pre_restore - Prepare for hibernate image restoration.
192  * @platform_mode: Whether or not to use the platform driver.
193  *
194  * Use the platform driver to prepare the system for resume from a hibernation
195  * image.
196  *
197  * If the restore fails after this function has been called,
198  * platform_restore_cleanup() must be called.
199  */
200 static int platform_pre_restore(int platform_mode)
201 {
202 	return (platform_mode && hibernation_ops) ?
203 		hibernation_ops->pre_restore() : 0;
204 }
205 
206 /**
207  * platform_restore_cleanup - Switch to the working state after failing restore.
208  * @platform_mode: Whether or not to use the platform driver.
209  *
210  * Use the platform driver to switch the system to the normal mode of operation
211  * after a failing restore.
212  *
213  * If platform_pre_restore() has been called before the failing restore, this
214  * function must be called too, regardless of the result of
215  * platform_pre_restore().
216  */
217 static void platform_restore_cleanup(int platform_mode)
218 {
219 	if (platform_mode && hibernation_ops)
220 		hibernation_ops->restore_cleanup();
221 }
222 
223 /**
224  * platform_recover - Recover from a failure to suspend devices.
225  * @platform_mode: Whether or not to use the platform driver.
226  */
227 static void platform_recover(int platform_mode)
228 {
229 	if (platform_mode && hibernation_ops && hibernation_ops->recover)
230 		hibernation_ops->recover();
231 }
232 
233 /**
234  * swsusp_show_speed - Print time elapsed between two events during hibernation.
235  * @start: Starting event.
236  * @stop: Final event.
237  * @nr_pages: Number of memory pages processed between @start and @stop.
238  * @msg: Additional diagnostic message to print.
239  */
240 void swsusp_show_speed(ktime_t start, ktime_t stop,
241 		      unsigned nr_pages, char *msg)
242 {
243 	ktime_t diff;
244 	u64 elapsed_centisecs64;
245 	unsigned int centisecs;
246 	unsigned int k;
247 	unsigned int kps;
248 
249 	diff = ktime_sub(stop, start);
250 	elapsed_centisecs64 = ktime_divns(diff, 10*NSEC_PER_MSEC);
251 	centisecs = elapsed_centisecs64;
252 	if (centisecs == 0)
253 		centisecs = 1;	/* avoid div-by-zero */
254 	k = nr_pages * (PAGE_SIZE / 1024);
255 	kps = (k * 100) / centisecs;
256 	pr_info("%s %u kbytes in %u.%02u seconds (%u.%02u MB/s)\n",
257 		msg, k, centisecs / 100, centisecs % 100, kps / 1000,
258 		(kps % 1000) / 10);
259 }
260 
261 /**
262  * create_image - Create a hibernation image.
263  * @platform_mode: Whether or not to use the platform driver.
264  *
265  * Execute device drivers' "late" and "noirq" freeze callbacks, create a
266  * hibernation image and run the drivers' "noirq" and "early" thaw callbacks.
267  *
268  * Control reappears in this routine after the subsequent restore.
269  */
270 static int create_image(int platform_mode)
271 {
272 	int error;
273 
274 	error = dpm_suspend_end(PMSG_FREEZE);
275 	if (error) {
276 		pr_err("Some devices failed to power down, aborting hibernation\n");
277 		return error;
278 	}
279 
280 	error = platform_pre_snapshot(platform_mode);
281 	if (error || hibernation_test(TEST_PLATFORM))
282 		goto Platform_finish;
283 
284 	error = disable_nonboot_cpus();
285 	if (error || hibernation_test(TEST_CPUS))
286 		goto Enable_cpus;
287 
288 	local_irq_disable();
289 
290 	error = syscore_suspend();
291 	if (error) {
292 		pr_err("Some system devices failed to power down, aborting hibernation\n");
293 		goto Enable_irqs;
294 	}
295 
296 	if (hibernation_test(TEST_CORE) || pm_wakeup_pending())
297 		goto Power_up;
298 
299 	in_suspend = 1;
300 	save_processor_state();
301 	trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, true);
302 	error = swsusp_arch_suspend();
303 	/* Restore control flow magically appears here */
304 	restore_processor_state();
305 	trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, false);
306 	if (error)
307 		pr_err("Error %d creating hibernation image\n", error);
308 
309 	if (!in_suspend) {
310 		events_check_enabled = false;
311 		clear_free_pages();
312 	}
313 
314 	platform_leave(platform_mode);
315 
316  Power_up:
317 	syscore_resume();
318 
319  Enable_irqs:
320 	local_irq_enable();
321 
322  Enable_cpus:
323 	enable_nonboot_cpus();
324 
325  Platform_finish:
326 	platform_finish(platform_mode);
327 
328 	dpm_resume_start(in_suspend ?
329 		(error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
330 
331 	return error;
332 }
333 
334 /**
335  * hibernation_snapshot - Quiesce devices and create a hibernation image.
336  * @platform_mode: If set, use platform driver to prepare for the transition.
337  *
338  * This routine must be called with pm_mutex held.
339  */
340 int hibernation_snapshot(int platform_mode)
341 {
342 	pm_message_t msg;
343 	int error;
344 
345 	pm_suspend_clear_flags();
346 	error = platform_begin(platform_mode);
347 	if (error)
348 		goto Close;
349 
350 	/* Preallocate image memory before shutting down devices. */
351 	error = hibernate_preallocate_memory();
352 	if (error)
353 		goto Close;
354 
355 	error = freeze_kernel_threads();
356 	if (error)
357 		goto Cleanup;
358 
359 	if (hibernation_test(TEST_FREEZER)) {
360 
361 		/*
362 		 * Indicate to the caller that we are returning due to a
363 		 * successful freezer test.
364 		 */
365 		freezer_test_done = true;
366 		goto Thaw;
367 	}
368 
369 	error = dpm_prepare(PMSG_FREEZE);
370 	if (error) {
371 		dpm_complete(PMSG_RECOVER);
372 		goto Thaw;
373 	}
374 
375 	suspend_console();
376 	pm_restrict_gfp_mask();
377 
378 	error = dpm_suspend(PMSG_FREEZE);
379 
380 	if (error || hibernation_test(TEST_DEVICES))
381 		platform_recover(platform_mode);
382 	else
383 		error = create_image(platform_mode);
384 
385 	/*
386 	 * In the case that we call create_image() above, the control
387 	 * returns here (1) after the image has been created or the
388 	 * image creation has failed and (2) after a successful restore.
389 	 */
390 
391 	/* We may need to release the preallocated image pages here. */
392 	if (error || !in_suspend)
393 		swsusp_free();
394 
395 	msg = in_suspend ? (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE;
396 	dpm_resume(msg);
397 
398 	if (error || !in_suspend)
399 		pm_restore_gfp_mask();
400 
401 	resume_console();
402 	dpm_complete(msg);
403 
404  Close:
405 	platform_end(platform_mode);
406 	return error;
407 
408  Thaw:
409 	thaw_kernel_threads();
410  Cleanup:
411 	swsusp_free();
412 	goto Close;
413 }
414 
415 int __weak hibernate_resume_nonboot_cpu_disable(void)
416 {
417 	return disable_nonboot_cpus();
418 }
419 
420 /**
421  * resume_target_kernel - Restore system state from a hibernation image.
422  * @platform_mode: Whether or not to use the platform driver.
423  *
424  * Execute device drivers' "noirq" and "late" freeze callbacks, restore the
425  * contents of highmem that have not been restored yet from the image and run
426  * the low-level code that will restore the remaining contents of memory and
427  * switch to the just restored target kernel.
428  */
429 static int resume_target_kernel(bool platform_mode)
430 {
431 	int error;
432 
433 	error = dpm_suspend_end(PMSG_QUIESCE);
434 	if (error) {
435 		pr_err("Some devices failed to power down, aborting resume\n");
436 		return error;
437 	}
438 
439 	error = platform_pre_restore(platform_mode);
440 	if (error)
441 		goto Cleanup;
442 
443 	error = hibernate_resume_nonboot_cpu_disable();
444 	if (error)
445 		goto Enable_cpus;
446 
447 	local_irq_disable();
448 
449 	error = syscore_suspend();
450 	if (error)
451 		goto Enable_irqs;
452 
453 	save_processor_state();
454 	error = restore_highmem();
455 	if (!error) {
456 		error = swsusp_arch_resume();
457 		/*
458 		 * The code below is only ever reached in case of a failure.
459 		 * Otherwise, execution continues at the place where
460 		 * swsusp_arch_suspend() was called.
461 		 */
462 		BUG_ON(!error);
463 		/*
464 		 * This call to restore_highmem() reverts the changes made by
465 		 * the previous one.
466 		 */
467 		restore_highmem();
468 	}
469 	/*
470 	 * The only reason why swsusp_arch_resume() can fail is memory being
471 	 * very tight, so we have to free it as soon as we can to avoid
472 	 * subsequent failures.
473 	 */
474 	swsusp_free();
475 	restore_processor_state();
476 	touch_softlockup_watchdog();
477 
478 	syscore_resume();
479 
480  Enable_irqs:
481 	local_irq_enable();
482 
483  Enable_cpus:
484 	enable_nonboot_cpus();
485 
486  Cleanup:
487 	platform_restore_cleanup(platform_mode);
488 
489 	dpm_resume_start(PMSG_RECOVER);
490 
491 	return error;
492 }
493 
494 /**
495  * hibernation_restore - Quiesce devices and restore from a hibernation image.
496  * @platform_mode: If set, use platform driver to prepare for the transition.
497  *
498  * This routine must be called with pm_mutex held.  If it is successful, control
499  * reappears in the restored target kernel in hibernation_snapshot().
500  */
501 int hibernation_restore(int platform_mode)
502 {
503 	int error;
504 
505 	pm_prepare_console();
506 	suspend_console();
507 	pm_restrict_gfp_mask();
508 	error = dpm_suspend_start(PMSG_QUIESCE);
509 	if (!error) {
510 		error = resume_target_kernel(platform_mode);
511 		/*
512 		 * The above should either succeed and jump to the new kernel,
513 		 * or return with an error. Otherwise things are just
514 		 * undefined, so let's be paranoid.
515 		 */
516 		BUG_ON(!error);
517 	}
518 	dpm_resume_end(PMSG_RECOVER);
519 	pm_restore_gfp_mask();
520 	resume_console();
521 	pm_restore_console();
522 	return error;
523 }
524 
525 /**
526  * hibernation_platform_enter - Power off the system using the platform driver.
527  */
528 int hibernation_platform_enter(void)
529 {
530 	int error;
531 
532 	if (!hibernation_ops)
533 		return -ENOSYS;
534 
535 	/*
536 	 * We have cancelled the power transition by running
537 	 * hibernation_ops->finish() before saving the image, so we should let
538 	 * the firmware know that we're going to enter the sleep state after all
539 	 */
540 	error = hibernation_ops->begin();
541 	if (error)
542 		goto Close;
543 
544 	entering_platform_hibernation = true;
545 	suspend_console();
546 	error = dpm_suspend_start(PMSG_HIBERNATE);
547 	if (error) {
548 		if (hibernation_ops->recover)
549 			hibernation_ops->recover();
550 		goto Resume_devices;
551 	}
552 
553 	error = dpm_suspend_end(PMSG_HIBERNATE);
554 	if (error)
555 		goto Resume_devices;
556 
557 	error = hibernation_ops->prepare();
558 	if (error)
559 		goto Platform_finish;
560 
561 	error = disable_nonboot_cpus();
562 	if (error)
563 		goto Enable_cpus;
564 
565 	local_irq_disable();
566 	syscore_suspend();
567 	if (pm_wakeup_pending()) {
568 		error = -EAGAIN;
569 		goto Power_up;
570 	}
571 
572 	hibernation_ops->enter();
573 	/* We should never get here */
574 	while (1);
575 
576  Power_up:
577 	syscore_resume();
578 	local_irq_enable();
579 
580  Enable_cpus:
581 	enable_nonboot_cpus();
582 
583  Platform_finish:
584 	hibernation_ops->finish();
585 
586 	dpm_resume_start(PMSG_RESTORE);
587 
588  Resume_devices:
589 	entering_platform_hibernation = false;
590 	dpm_resume_end(PMSG_RESTORE);
591 	resume_console();
592 
593  Close:
594 	hibernation_ops->end();
595 
596 	return error;
597 }
598 
599 /**
600  * power_down - Shut the machine down for hibernation.
601  *
602  * Use the platform driver, if configured, to put the system into the sleep
603  * state corresponding to hibernation, or try to power it off or reboot,
604  * depending on the value of hibernation_mode.
605  */
606 static void power_down(void)
607 {
608 #ifdef CONFIG_SUSPEND
609 	int error;
610 
611 	if (hibernation_mode == HIBERNATION_SUSPEND) {
612 		error = suspend_devices_and_enter(PM_SUSPEND_MEM);
613 		if (error) {
614 			hibernation_mode = hibernation_ops ?
615 						HIBERNATION_PLATFORM :
616 						HIBERNATION_SHUTDOWN;
617 		} else {
618 			/* Restore swap signature. */
619 			error = swsusp_unmark();
620 			if (error)
621 				pr_err("Swap will be unusable! Try swapon -a.\n");
622 
623 			return;
624 		}
625 	}
626 #endif
627 
628 	switch (hibernation_mode) {
629 	case HIBERNATION_REBOOT:
630 		kernel_restart(NULL);
631 		break;
632 	case HIBERNATION_PLATFORM:
633 		hibernation_platform_enter();
634 	case HIBERNATION_SHUTDOWN:
635 		if (pm_power_off)
636 			kernel_power_off();
637 		break;
638 	}
639 	kernel_halt();
640 	/*
641 	 * Valid image is on the disk, if we continue we risk serious data
642 	 * corruption after resume.
643 	 */
644 	pr_crit("Power down manually\n");
645 	while (1)
646 		cpu_relax();
647 }
648 
649 static int load_image_and_restore(void)
650 {
651 	int error;
652 	unsigned int flags;
653 
654 	pr_debug("Loading hibernation image.\n");
655 
656 	lock_device_hotplug();
657 	error = create_basic_memory_bitmaps();
658 	if (error)
659 		goto Unlock;
660 
661 	error = swsusp_read(&flags);
662 	swsusp_close(FMODE_READ);
663 	if (!error)
664 		hibernation_restore(flags & SF_PLATFORM_MODE);
665 
666 	pr_err("Failed to load hibernation image, recovering.\n");
667 	swsusp_free();
668 	free_basic_memory_bitmaps();
669  Unlock:
670 	unlock_device_hotplug();
671 
672 	return error;
673 }
674 
675 /**
676  * hibernate - Carry out system hibernation, including saving the image.
677  */
678 int hibernate(void)
679 {
680 	int error, nr_calls = 0;
681 	bool snapshot_test = false;
682 
683 	if (!hibernation_available()) {
684 		pr_debug("Hibernation not available.\n");
685 		return -EPERM;
686 	}
687 
688 	lock_system_sleep();
689 	/* The snapshot device should not be opened while we're running */
690 	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
691 		error = -EBUSY;
692 		goto Unlock;
693 	}
694 
695 	pm_prepare_console();
696 	error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
697 	if (error) {
698 		nr_calls--;
699 		goto Exit;
700 	}
701 
702 	pr_info("Syncing filesystems ... \n");
703 	sys_sync();
704 	pr_info("done.\n");
705 
706 	error = freeze_processes();
707 	if (error)
708 		goto Exit;
709 
710 	lock_device_hotplug();
711 	/* Allocate memory management structures */
712 	error = create_basic_memory_bitmaps();
713 	if (error)
714 		goto Thaw;
715 
716 	error = hibernation_snapshot(hibernation_mode == HIBERNATION_PLATFORM);
717 	if (error || freezer_test_done)
718 		goto Free_bitmaps;
719 
720 	if (in_suspend) {
721 		unsigned int flags = 0;
722 
723 		if (hibernation_mode == HIBERNATION_PLATFORM)
724 			flags |= SF_PLATFORM_MODE;
725 		if (nocompress)
726 			flags |= SF_NOCOMPRESS_MODE;
727 		else
728 		        flags |= SF_CRC32_MODE;
729 
730 		pr_debug("Writing image.\n");
731 		error = swsusp_write(flags);
732 		swsusp_free();
733 		if (!error) {
734 			if (hibernation_mode == HIBERNATION_TEST_RESUME)
735 				snapshot_test = true;
736 			else
737 				power_down();
738 		}
739 		in_suspend = 0;
740 		pm_restore_gfp_mask();
741 	} else {
742 		pr_debug("Image restored successfully.\n");
743 	}
744 
745  Free_bitmaps:
746 	free_basic_memory_bitmaps();
747  Thaw:
748 	unlock_device_hotplug();
749 	if (snapshot_test) {
750 		pr_debug("Checking hibernation image\n");
751 		error = swsusp_check();
752 		if (!error)
753 			error = load_image_and_restore();
754 	}
755 	thaw_processes();
756 
757 	/* Don't bother checking whether freezer_test_done is true */
758 	freezer_test_done = false;
759  Exit:
760 	__pm_notifier_call_chain(PM_POST_HIBERNATION, nr_calls, NULL);
761 	pm_restore_console();
762 	atomic_inc(&snapshot_device_available);
763  Unlock:
764 	unlock_system_sleep();
765 	return error;
766 }
767 
768 
769 /**
770  * software_resume - Resume from a saved hibernation image.
771  *
772  * This routine is called as a late initcall, when all devices have been
773  * discovered and initialized already.
774  *
775  * The image reading code is called to see if there is a hibernation image
776  * available for reading.  If that is the case, devices are quiesced and the
777  * contents of memory is restored from the saved image.
778  *
779  * If this is successful, control reappears in the restored target kernel in
780  * hibernation_snapshot() which returns to hibernate().  Otherwise, the routine
781  * attempts to recover gracefully and make the kernel return to the normal mode
782  * of operation.
783  */
784 static int software_resume(void)
785 {
786 	int error, nr_calls = 0;
787 
788 	/*
789 	 * If the user said "noresume".. bail out early.
790 	 */
791 	if (noresume || !hibernation_available())
792 		return 0;
793 
794 	/*
795 	 * name_to_dev_t() below takes a sysfs buffer mutex when sysfs
796 	 * is configured into the kernel. Since the regular hibernate
797 	 * trigger path is via sysfs which takes a buffer mutex before
798 	 * calling hibernate functions (which take pm_mutex) this can
799 	 * cause lockdep to complain about a possible ABBA deadlock
800 	 * which cannot happen since we're in the boot code here and
801 	 * sysfs can't be invoked yet. Therefore, we use a subclass
802 	 * here to avoid lockdep complaining.
803 	 */
804 	mutex_lock_nested(&pm_mutex, SINGLE_DEPTH_NESTING);
805 
806 	if (swsusp_resume_device)
807 		goto Check_image;
808 
809 	if (!strlen(resume_file)) {
810 		error = -ENOENT;
811 		goto Unlock;
812 	}
813 
814 	pr_debug("Checking hibernation image partition %s\n", resume_file);
815 
816 	if (resume_delay) {
817 		pr_info("Waiting %dsec before reading resume device ...\n",
818 			resume_delay);
819 		ssleep(resume_delay);
820 	}
821 
822 	/* Check if the device is there */
823 	swsusp_resume_device = name_to_dev_t(resume_file);
824 
825 	/*
826 	 * name_to_dev_t is ineffective to verify parition if resume_file is in
827 	 * integer format. (e.g. major:minor)
828 	 */
829 	if (isdigit(resume_file[0]) && resume_wait) {
830 		int partno;
831 		while (!get_gendisk(swsusp_resume_device, &partno))
832 			msleep(10);
833 	}
834 
835 	if (!swsusp_resume_device) {
836 		/*
837 		 * Some device discovery might still be in progress; we need
838 		 * to wait for this to finish.
839 		 */
840 		wait_for_device_probe();
841 
842 		if (resume_wait) {
843 			while ((swsusp_resume_device = name_to_dev_t(resume_file)) == 0)
844 				msleep(10);
845 			async_synchronize_full();
846 		}
847 
848 		swsusp_resume_device = name_to_dev_t(resume_file);
849 		if (!swsusp_resume_device) {
850 			error = -ENODEV;
851 			goto Unlock;
852 		}
853 	}
854 
855  Check_image:
856 	pr_debug("Hibernation image partition %d:%d present\n",
857 		MAJOR(swsusp_resume_device), MINOR(swsusp_resume_device));
858 
859 	pr_debug("Looking for hibernation image.\n");
860 	error = swsusp_check();
861 	if (error)
862 		goto Unlock;
863 
864 	/* The snapshot device should not be opened while we're running */
865 	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
866 		error = -EBUSY;
867 		swsusp_close(FMODE_READ);
868 		goto Unlock;
869 	}
870 
871 	pm_prepare_console();
872 	error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls);
873 	if (error) {
874 		nr_calls--;
875 		goto Close_Finish;
876 	}
877 
878 	pr_debug("Preparing processes for restore.\n");
879 	error = freeze_processes();
880 	if (error)
881 		goto Close_Finish;
882 	error = load_image_and_restore();
883 	thaw_processes();
884  Finish:
885 	__pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
886 	pm_restore_console();
887 	atomic_inc(&snapshot_device_available);
888 	/* For success case, the suspend path will release the lock */
889  Unlock:
890 	mutex_unlock(&pm_mutex);
891 	pr_debug("Hibernation image not present or could not be loaded.\n");
892 	return error;
893  Close_Finish:
894 	swsusp_close(FMODE_READ);
895 	goto Finish;
896 }
897 
898 late_initcall_sync(software_resume);
899 
900 
901 static const char * const hibernation_modes[] = {
902 	[HIBERNATION_PLATFORM]	= "platform",
903 	[HIBERNATION_SHUTDOWN]	= "shutdown",
904 	[HIBERNATION_REBOOT]	= "reboot",
905 #ifdef CONFIG_SUSPEND
906 	[HIBERNATION_SUSPEND]	= "suspend",
907 #endif
908 	[HIBERNATION_TEST_RESUME]	= "test_resume",
909 };
910 
911 /*
912  * /sys/power/disk - Control hibernation mode.
913  *
914  * Hibernation can be handled in several ways.  There are a few different ways
915  * to put the system into the sleep state: using the platform driver (e.g. ACPI
916  * or other hibernation_ops), powering it off or rebooting it (for testing
917  * mostly).
918  *
919  * The sysfs file /sys/power/disk provides an interface for selecting the
920  * hibernation mode to use.  Reading from this file causes the available modes
921  * to be printed.  There are 3 modes that can be supported:
922  *
923  *	'platform'
924  *	'shutdown'
925  *	'reboot'
926  *
927  * If a platform hibernation driver is in use, 'platform' will be supported
928  * and will be used by default.  Otherwise, 'shutdown' will be used by default.
929  * The selected option (i.e. the one corresponding to the current value of
930  * hibernation_mode) is enclosed by a square bracket.
931  *
932  * To select a given hibernation mode it is necessary to write the mode's
933  * string representation (as returned by reading from /sys/power/disk) back
934  * into /sys/power/disk.
935  */
936 
937 static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
938 			 char *buf)
939 {
940 	int i;
941 	char *start = buf;
942 
943 	if (!hibernation_available())
944 		return sprintf(buf, "[disabled]\n");
945 
946 	for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
947 		if (!hibernation_modes[i])
948 			continue;
949 		switch (i) {
950 		case HIBERNATION_SHUTDOWN:
951 		case HIBERNATION_REBOOT:
952 #ifdef CONFIG_SUSPEND
953 		case HIBERNATION_SUSPEND:
954 #endif
955 		case HIBERNATION_TEST_RESUME:
956 			break;
957 		case HIBERNATION_PLATFORM:
958 			if (hibernation_ops)
959 				break;
960 			/* not a valid mode, continue with loop */
961 			continue;
962 		}
963 		if (i == hibernation_mode)
964 			buf += sprintf(buf, "[%s] ", hibernation_modes[i]);
965 		else
966 			buf += sprintf(buf, "%s ", hibernation_modes[i]);
967 	}
968 	buf += sprintf(buf, "\n");
969 	return buf-start;
970 }
971 
972 static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
973 			  const char *buf, size_t n)
974 {
975 	int error = 0;
976 	int i;
977 	int len;
978 	char *p;
979 	int mode = HIBERNATION_INVALID;
980 
981 	if (!hibernation_available())
982 		return -EPERM;
983 
984 	p = memchr(buf, '\n', n);
985 	len = p ? p - buf : n;
986 
987 	lock_system_sleep();
988 	for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
989 		if (len == strlen(hibernation_modes[i])
990 		    && !strncmp(buf, hibernation_modes[i], len)) {
991 			mode = i;
992 			break;
993 		}
994 	}
995 	if (mode != HIBERNATION_INVALID) {
996 		switch (mode) {
997 		case HIBERNATION_SHUTDOWN:
998 		case HIBERNATION_REBOOT:
999 #ifdef CONFIG_SUSPEND
1000 		case HIBERNATION_SUSPEND:
1001 #endif
1002 		case HIBERNATION_TEST_RESUME:
1003 			hibernation_mode = mode;
1004 			break;
1005 		case HIBERNATION_PLATFORM:
1006 			if (hibernation_ops)
1007 				hibernation_mode = mode;
1008 			else
1009 				error = -EINVAL;
1010 		}
1011 	} else
1012 		error = -EINVAL;
1013 
1014 	if (!error)
1015 		pr_debug("Hibernation mode set to '%s'\n",
1016 			 hibernation_modes[mode]);
1017 	unlock_system_sleep();
1018 	return error ? error : n;
1019 }
1020 
1021 power_attr(disk);
1022 
1023 static ssize_t resume_show(struct kobject *kobj, struct kobj_attribute *attr,
1024 			   char *buf)
1025 {
1026 	return sprintf(buf,"%d:%d\n", MAJOR(swsusp_resume_device),
1027 		       MINOR(swsusp_resume_device));
1028 }
1029 
1030 static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
1031 			    const char *buf, size_t n)
1032 {
1033 	dev_t res;
1034 	int len = n;
1035 	char *name;
1036 
1037 	if (len && buf[len-1] == '\n')
1038 		len--;
1039 	name = kstrndup(buf, len, GFP_KERNEL);
1040 	if (!name)
1041 		return -ENOMEM;
1042 
1043 	res = name_to_dev_t(name);
1044 	kfree(name);
1045 	if (!res)
1046 		return -EINVAL;
1047 
1048 	lock_system_sleep();
1049 	swsusp_resume_device = res;
1050 	unlock_system_sleep();
1051 	pr_info("Starting manual resume from disk\n");
1052 	noresume = 0;
1053 	software_resume();
1054 	return n;
1055 }
1056 
1057 power_attr(resume);
1058 
1059 static ssize_t image_size_show(struct kobject *kobj, struct kobj_attribute *attr,
1060 			       char *buf)
1061 {
1062 	return sprintf(buf, "%lu\n", image_size);
1063 }
1064 
1065 static ssize_t image_size_store(struct kobject *kobj, struct kobj_attribute *attr,
1066 				const char *buf, size_t n)
1067 {
1068 	unsigned long size;
1069 
1070 	if (sscanf(buf, "%lu", &size) == 1) {
1071 		image_size = size;
1072 		return n;
1073 	}
1074 
1075 	return -EINVAL;
1076 }
1077 
1078 power_attr(image_size);
1079 
1080 static ssize_t reserved_size_show(struct kobject *kobj,
1081 				  struct kobj_attribute *attr, char *buf)
1082 {
1083 	return sprintf(buf, "%lu\n", reserved_size);
1084 }
1085 
1086 static ssize_t reserved_size_store(struct kobject *kobj,
1087 				   struct kobj_attribute *attr,
1088 				   const char *buf, size_t n)
1089 {
1090 	unsigned long size;
1091 
1092 	if (sscanf(buf, "%lu", &size) == 1) {
1093 		reserved_size = size;
1094 		return n;
1095 	}
1096 
1097 	return -EINVAL;
1098 }
1099 
1100 power_attr(reserved_size);
1101 
1102 static struct attribute * g[] = {
1103 	&disk_attr.attr,
1104 	&resume_attr.attr,
1105 	&image_size_attr.attr,
1106 	&reserved_size_attr.attr,
1107 	NULL,
1108 };
1109 
1110 
1111 static const struct attribute_group attr_group = {
1112 	.attrs = g,
1113 };
1114 
1115 
1116 static int __init pm_disk_init(void)
1117 {
1118 	return sysfs_create_group(power_kobj, &attr_group);
1119 }
1120 
1121 core_initcall(pm_disk_init);
1122 
1123 
1124 static int __init resume_setup(char *str)
1125 {
1126 	if (noresume)
1127 		return 1;
1128 
1129 	strncpy( resume_file, str, 255 );
1130 	return 1;
1131 }
1132 
1133 static int __init resume_offset_setup(char *str)
1134 {
1135 	unsigned long long offset;
1136 
1137 	if (noresume)
1138 		return 1;
1139 
1140 	if (sscanf(str, "%llu", &offset) == 1)
1141 		swsusp_resume_block = offset;
1142 
1143 	return 1;
1144 }
1145 
1146 static int __init hibernate_setup(char *str)
1147 {
1148 	if (!strncmp(str, "noresume", 8)) {
1149 		noresume = 1;
1150 	} else if (!strncmp(str, "nocompress", 10)) {
1151 		nocompress = 1;
1152 	} else if (!strncmp(str, "no", 2)) {
1153 		noresume = 1;
1154 		nohibernate = 1;
1155 	} else if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)
1156 		   && !strncmp(str, "protect_image", 13)) {
1157 		enable_restore_image_protection();
1158 	}
1159 	return 1;
1160 }
1161 
1162 static int __init noresume_setup(char *str)
1163 {
1164 	noresume = 1;
1165 	return 1;
1166 }
1167 
1168 static int __init resumewait_setup(char *str)
1169 {
1170 	resume_wait = 1;
1171 	return 1;
1172 }
1173 
1174 static int __init resumedelay_setup(char *str)
1175 {
1176 	int rc = kstrtouint(str, 0, &resume_delay);
1177 
1178 	if (rc)
1179 		return rc;
1180 	return 1;
1181 }
1182 
1183 static int __init nohibernate_setup(char *str)
1184 {
1185 	noresume = 1;
1186 	nohibernate = 1;
1187 	return 1;
1188 }
1189 
1190 __setup("noresume", noresume_setup);
1191 __setup("resume_offset=", resume_offset_setup);
1192 __setup("resume=", resume_setup);
1193 __setup("hibernate=", hibernate_setup);
1194 __setup("resumewait", resumewait_setup);
1195 __setup("resumedelay=", resumedelay_setup);
1196 __setup("nohibernate", nohibernate_setup);
1197