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TOMOYO Linux Cross Reference
Linux/kernel/power/hibernate.c

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * kernel/power/hibernate.c - Hibernation (a.k.a suspend-to-disk) support.
  4  *
  5  * Copyright (c) 2003 Patrick Mochel
  6  * Copyright (c) 2003 Open Source Development Lab
  7  * Copyright (c) 2004 Pavel Machek <pavel@ucw.cz>
  8  * Copyright (c) 2009 Rafael J. Wysocki, Novell Inc.
  9  * Copyright (C) 2012 Bojan Smojver <bojan@rexursive.com>
 10  */
 11 
 12 #define pr_fmt(fmt) "PM: " fmt
 13 
 14 #include <linux/export.h>
 15 #include <linux/suspend.h>
 16 #include <linux/reboot.h>
 17 #include <linux/string.h>
 18 #include <linux/device.h>
 19 #include <linux/async.h>
 20 #include <linux/delay.h>
 21 #include <linux/fs.h>
 22 #include <linux/mount.h>
 23 #include <linux/pm.h>
 24 #include <linux/nmi.h>
 25 #include <linux/console.h>
 26 #include <linux/cpu.h>
 27 #include <linux/freezer.h>
 28 #include <linux/gfp.h>
 29 #include <linux/syscore_ops.h>
 30 #include <linux/ctype.h>
 31 #include <linux/genhd.h>
 32 #include <linux/ktime.h>
 33 #include <trace/events/power.h>
 34 
 35 #include "power.h"
 36 
 37 
 38 static int nocompress;
 39 static int noresume;
 40 static int nohibernate;
 41 static int resume_wait;
 42 static unsigned int resume_delay;
 43 static char resume_file[256] = CONFIG_PM_STD_PARTITION;
 44 dev_t swsusp_resume_device;
 45 sector_t swsusp_resume_block;
 46 __visible int in_suspend __nosavedata;
 47 
 48 enum {
 49         HIBERNATION_INVALID,
 50         HIBERNATION_PLATFORM,
 51         HIBERNATION_SHUTDOWN,
 52         HIBERNATION_REBOOT,
 53 #ifdef CONFIG_SUSPEND
 54         HIBERNATION_SUSPEND,
 55 #endif
 56         HIBERNATION_TEST_RESUME,
 57         /* keep last */
 58         __HIBERNATION_AFTER_LAST
 59 };
 60 #define HIBERNATION_MAX (__HIBERNATION_AFTER_LAST-1)
 61 #define HIBERNATION_FIRST (HIBERNATION_INVALID + 1)
 62 
 63 static int hibernation_mode = HIBERNATION_SHUTDOWN;
 64 
 65 bool freezer_test_done;
 66 
 67 static const struct platform_hibernation_ops *hibernation_ops;
 68 
 69 bool hibernation_available(void)
 70 {
 71         return (nohibernate == 0);
 72 }
 73 
 74 /**
 75  * hibernation_set_ops - Set the global hibernate operations.
 76  * @ops: Hibernation operations to use in subsequent hibernation transitions.
 77  */
 78 void hibernation_set_ops(const struct platform_hibernation_ops *ops)
 79 {
 80         if (ops && !(ops->begin && ops->end &&  ops->pre_snapshot
 81             && ops->prepare && ops->finish && ops->enter && ops->pre_restore
 82             && ops->restore_cleanup && ops->leave)) {
 83                 WARN_ON(1);
 84                 return;
 85         }
 86         lock_system_sleep();
 87         hibernation_ops = ops;
 88         if (ops)
 89                 hibernation_mode = HIBERNATION_PLATFORM;
 90         else if (hibernation_mode == HIBERNATION_PLATFORM)
 91                 hibernation_mode = HIBERNATION_SHUTDOWN;
 92 
 93         unlock_system_sleep();
 94 }
 95 EXPORT_SYMBOL_GPL(hibernation_set_ops);
 96 
 97 static bool entering_platform_hibernation;
 98 
 99 bool system_entering_hibernation(void)
100 {
101         return entering_platform_hibernation;
102 }
103 EXPORT_SYMBOL(system_entering_hibernation);
104 
105 #ifdef CONFIG_PM_DEBUG
106 static void hibernation_debug_sleep(void)
107 {
108         pr_info("hibernation debug: Waiting for 5 seconds.\n");
109         mdelay(5000);
110 }
111 
112 static int hibernation_test(int level)
113 {
114         if (pm_test_level == level) {
115                 hibernation_debug_sleep();
116                 return 1;
117         }
118         return 0;
119 }
120 #else /* !CONFIG_PM_DEBUG */
121 static int hibernation_test(int level) { return 0; }
122 #endif /* !CONFIG_PM_DEBUG */
123 
124 /**
125  * platform_begin - Call platform to start hibernation.
126  * @platform_mode: Whether or not to use the platform driver.
127  */
128 static int platform_begin(int platform_mode)
129 {
130         return (platform_mode && hibernation_ops) ?
131                 hibernation_ops->begin(PMSG_FREEZE) : 0;
132 }
133 
134 /**
135  * platform_end - Call platform to finish transition to the working state.
136  * @platform_mode: Whether or not to use the platform driver.
137  */
138 static void platform_end(int platform_mode)
139 {
140         if (platform_mode && hibernation_ops)
141                 hibernation_ops->end();
142 }
143 
144 /**
145  * platform_pre_snapshot - Call platform to prepare the machine for hibernation.
146  * @platform_mode: Whether or not to use the platform driver.
147  *
148  * Use the platform driver to prepare the system for creating a hibernate image,
149  * if so configured, and return an error code if that fails.
150  */
151 
152 static int platform_pre_snapshot(int platform_mode)
153 {
154         return (platform_mode && hibernation_ops) ?
155                 hibernation_ops->pre_snapshot() : 0;
156 }
157 
158 /**
159  * platform_leave - Call platform to prepare a transition to the working state.
160  * @platform_mode: Whether or not to use the platform driver.
161  *
162  * Use the platform driver prepare to prepare the machine for switching to the
163  * normal mode of operation.
164  *
165  * This routine is called on one CPU with interrupts disabled.
166  */
167 static void platform_leave(int platform_mode)
168 {
169         if (platform_mode && hibernation_ops)
170                 hibernation_ops->leave();
171 }
172 
173 /**
174  * platform_finish - Call platform to switch the system to the working state.
175  * @platform_mode: Whether or not to use the platform driver.
176  *
177  * Use the platform driver to switch the machine to the normal mode of
178  * operation.
179  *
180  * This routine must be called after platform_prepare().
181  */
182 static void platform_finish(int platform_mode)
183 {
184         if (platform_mode && hibernation_ops)
185                 hibernation_ops->finish();
186 }
187 
188 /**
189  * platform_pre_restore - Prepare for hibernate image restoration.
190  * @platform_mode: Whether or not to use the platform driver.
191  *
192  * Use the platform driver to prepare the system for resume from a hibernation
193  * image.
194  *
195  * If the restore fails after this function has been called,
196  * platform_restore_cleanup() must be called.
197  */
198 static int platform_pre_restore(int platform_mode)
199 {
200         return (platform_mode && hibernation_ops) ?
201                 hibernation_ops->pre_restore() : 0;
202 }
203 
204 /**
205  * platform_restore_cleanup - Switch to the working state after failing restore.
206  * @platform_mode: Whether or not to use the platform driver.
207  *
208  * Use the platform driver to switch the system to the normal mode of operation
209  * after a failing restore.
210  *
211  * If platform_pre_restore() has been called before the failing restore, this
212  * function must be called too, regardless of the result of
213  * platform_pre_restore().
214  */
215 static void platform_restore_cleanup(int platform_mode)
216 {
217         if (platform_mode && hibernation_ops)
218                 hibernation_ops->restore_cleanup();
219 }
220 
221 /**
222  * platform_recover - Recover from a failure to suspend devices.
223  * @platform_mode: Whether or not to use the platform driver.
224  */
225 static void platform_recover(int platform_mode)
226 {
227         if (platform_mode && hibernation_ops && hibernation_ops->recover)
228                 hibernation_ops->recover();
229 }
230 
231 /**
232  * swsusp_show_speed - Print time elapsed between two events during hibernation.
233  * @start: Starting event.
234  * @stop: Final event.
235  * @nr_pages: Number of memory pages processed between @start and @stop.
236  * @msg: Additional diagnostic message to print.
237  */
238 void swsusp_show_speed(ktime_t start, ktime_t stop,
239                       unsigned nr_pages, char *msg)
240 {
241         ktime_t diff;
242         u64 elapsed_centisecs64;
243         unsigned int centisecs;
244         unsigned int k;
245         unsigned int kps;
246 
247         diff = ktime_sub(stop, start);
248         elapsed_centisecs64 = ktime_divns(diff, 10*NSEC_PER_MSEC);
249         centisecs = elapsed_centisecs64;
250         if (centisecs == 0)
251                 centisecs = 1;  /* avoid div-by-zero */
252         k = nr_pages * (PAGE_SIZE / 1024);
253         kps = (k * 100) / centisecs;
254         pr_info("%s %u kbytes in %u.%02u seconds (%u.%02u MB/s)\n",
255                 msg, k, centisecs / 100, centisecs % 100, kps / 1000,
256                 (kps % 1000) / 10);
257 }
258 
259 __weak int arch_resume_nosmt(void)
260 {
261         return 0;
262 }
263 
264 /**
265  * create_image - Create a hibernation image.
266  * @platform_mode: Whether or not to use the platform driver.
267  *
268  * Execute device drivers' "late" and "noirq" freeze callbacks, create a
269  * hibernation image and run the drivers' "noirq" and "early" thaw callbacks.
270  *
271  * Control reappears in this routine after the subsequent restore.
272  */
273 static int create_image(int platform_mode)
274 {
275         int error;
276 
277         error = dpm_suspend_end(PMSG_FREEZE);
278         if (error) {
279                 pr_err("Some devices failed to power down, aborting hibernation\n");
280                 return error;
281         }
282 
283         error = platform_pre_snapshot(platform_mode);
284         if (error || hibernation_test(TEST_PLATFORM))
285                 goto Platform_finish;
286 
287         error = suspend_disable_secondary_cpus();
288         if (error || hibernation_test(TEST_CPUS))
289                 goto Enable_cpus;
290 
291         local_irq_disable();
292 
293         system_state = SYSTEM_SUSPEND;
294 
295         error = syscore_suspend();
296         if (error) {
297                 pr_err("Some system devices failed to power down, aborting hibernation\n");
298                 goto Enable_irqs;
299         }
300 
301         if (hibernation_test(TEST_CORE) || pm_wakeup_pending())
302                 goto Power_up;
303 
304         in_suspend = 1;
305         save_processor_state();
306         trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, true);
307         error = swsusp_arch_suspend();
308         /* Restore control flow magically appears here */
309         restore_processor_state();
310         trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, false);
311         if (error)
312                 pr_err("Error %d creating hibernation image\n", error);
313 
314         if (!in_suspend) {
315                 events_check_enabled = false;
316                 clear_free_pages();
317         }
318 
319         platform_leave(platform_mode);
320 
321  Power_up:
322         syscore_resume();
323 
324  Enable_irqs:
325         system_state = SYSTEM_RUNNING;
326         local_irq_enable();
327 
328  Enable_cpus:
329         suspend_enable_secondary_cpus();
330 
331         /* Allow architectures to do nosmt-specific post-resume dances */
332         if (!in_suspend)
333                 error = arch_resume_nosmt();
334 
335  Platform_finish:
336         platform_finish(platform_mode);
337 
338         dpm_resume_start(in_suspend ?
339                 (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
340 
341         return error;
342 }
343 
344 /**
345  * hibernation_snapshot - Quiesce devices and create a hibernation image.
346  * @platform_mode: If set, use platform driver to prepare for the transition.
347  *
348  * This routine must be called with system_transition_mutex held.
349  */
350 int hibernation_snapshot(int platform_mode)
351 {
352         pm_message_t msg;
353         int error;
354 
355         pm_suspend_clear_flags();
356         error = platform_begin(platform_mode);
357         if (error)
358                 goto Close;
359 
360         /* Preallocate image memory before shutting down devices. */
361         error = hibernate_preallocate_memory();
362         if (error)
363                 goto Close;
364 
365         error = freeze_kernel_threads();
366         if (error)
367                 goto Cleanup;
368 
369         if (hibernation_test(TEST_FREEZER)) {
370 
371                 /*
372                  * Indicate to the caller that we are returning due to a
373                  * successful freezer test.
374                  */
375                 freezer_test_done = true;
376                 goto Thaw;
377         }
378 
379         error = dpm_prepare(PMSG_FREEZE);
380         if (error) {
381                 dpm_complete(PMSG_RECOVER);
382                 goto Thaw;
383         }
384 
385         suspend_console();
386         pm_restrict_gfp_mask();
387 
388         error = dpm_suspend(PMSG_FREEZE);
389 
390         if (error || hibernation_test(TEST_DEVICES))
391                 platform_recover(platform_mode);
392         else
393                 error = create_image(platform_mode);
394 
395         /*
396          * In the case that we call create_image() above, the control
397          * returns here (1) after the image has been created or the
398          * image creation has failed and (2) after a successful restore.
399          */
400 
401         /* We may need to release the preallocated image pages here. */
402         if (error || !in_suspend)
403                 swsusp_free();
404 
405         msg = in_suspend ? (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE;
406         dpm_resume(msg);
407 
408         if (error || !in_suspend)
409                 pm_restore_gfp_mask();
410 
411         resume_console();
412         dpm_complete(msg);
413 
414  Close:
415         platform_end(platform_mode);
416         return error;
417 
418  Thaw:
419         thaw_kernel_threads();
420  Cleanup:
421         swsusp_free();
422         goto Close;
423 }
424 
425 int __weak hibernate_resume_nonboot_cpu_disable(void)
426 {
427         return suspend_disable_secondary_cpus();
428 }
429 
430 /**
431  * resume_target_kernel - Restore system state from a hibernation image.
432  * @platform_mode: Whether or not to use the platform driver.
433  *
434  * Execute device drivers' "noirq" and "late" freeze callbacks, restore the
435  * contents of highmem that have not been restored yet from the image and run
436  * the low-level code that will restore the remaining contents of memory and
437  * switch to the just restored target kernel.
438  */
439 static int resume_target_kernel(bool platform_mode)
440 {
441         int error;
442 
443         error = dpm_suspend_end(PMSG_QUIESCE);
444         if (error) {
445                 pr_err("Some devices failed to power down, aborting resume\n");
446                 return error;
447         }
448 
449         error = platform_pre_restore(platform_mode);
450         if (error)
451                 goto Cleanup;
452 
453         error = hibernate_resume_nonboot_cpu_disable();
454         if (error)
455                 goto Enable_cpus;
456 
457         local_irq_disable();
458         system_state = SYSTEM_SUSPEND;
459 
460         error = syscore_suspend();
461         if (error)
462                 goto Enable_irqs;
463 
464         save_processor_state();
465         error = restore_highmem();
466         if (!error) {
467                 error = swsusp_arch_resume();
468                 /*
469                  * The code below is only ever reached in case of a failure.
470                  * Otherwise, execution continues at the place where
471                  * swsusp_arch_suspend() was called.
472                  */
473                 BUG_ON(!error);
474                 /*
475                  * This call to restore_highmem() reverts the changes made by
476                  * the previous one.
477                  */
478                 restore_highmem();
479         }
480         /*
481          * The only reason why swsusp_arch_resume() can fail is memory being
482          * very tight, so we have to free it as soon as we can to avoid
483          * subsequent failures.
484          */
485         swsusp_free();
486         restore_processor_state();
487         touch_softlockup_watchdog();
488 
489         syscore_resume();
490 
491  Enable_irqs:
492         system_state = SYSTEM_RUNNING;
493         local_irq_enable();
494 
495  Enable_cpus:
496         suspend_enable_secondary_cpus();
497 
498  Cleanup:
499         platform_restore_cleanup(platform_mode);
500 
501         dpm_resume_start(PMSG_RECOVER);
502 
503         return error;
504 }
505 
506 /**
507  * hibernation_restore - Quiesce devices and restore from a hibernation image.
508  * @platform_mode: If set, use platform driver to prepare for the transition.
509  *
510  * This routine must be called with system_transition_mutex held.  If it is
511  * successful, control reappears in the restored target kernel in
512  * hibernation_snapshot().
513  */
514 int hibernation_restore(int platform_mode)
515 {
516         int error;
517 
518         pm_prepare_console();
519         suspend_console();
520         pm_restrict_gfp_mask();
521         error = dpm_suspend_start(PMSG_QUIESCE);
522         if (!error) {
523                 error = resume_target_kernel(platform_mode);
524                 /*
525                  * The above should either succeed and jump to the new kernel,
526                  * or return with an error. Otherwise things are just
527                  * undefined, so let's be paranoid.
528                  */
529                 BUG_ON(!error);
530         }
531         dpm_resume_end(PMSG_RECOVER);
532         pm_restore_gfp_mask();
533         resume_console();
534         pm_restore_console();
535         return error;
536 }
537 
538 /**
539  * hibernation_platform_enter - Power off the system using the platform driver.
540  */
541 int hibernation_platform_enter(void)
542 {
543         int error;
544 
545         if (!hibernation_ops)
546                 return -ENOSYS;
547 
548         /*
549          * We have cancelled the power transition by running
550          * hibernation_ops->finish() before saving the image, so we should let
551          * the firmware know that we're going to enter the sleep state after all
552          */
553         error = hibernation_ops->begin(PMSG_HIBERNATE);
554         if (error)
555                 goto Close;
556 
557         entering_platform_hibernation = true;
558         suspend_console();
559         error = dpm_suspend_start(PMSG_HIBERNATE);
560         if (error) {
561                 if (hibernation_ops->recover)
562                         hibernation_ops->recover();
563                 goto Resume_devices;
564         }
565 
566         error = dpm_suspend_end(PMSG_HIBERNATE);
567         if (error)
568                 goto Resume_devices;
569 
570         error = hibernation_ops->prepare();
571         if (error)
572                 goto Platform_finish;
573 
574         error = suspend_disable_secondary_cpus();
575         if (error)
576                 goto Enable_cpus;
577 
578         local_irq_disable();
579         system_state = SYSTEM_SUSPEND;
580         syscore_suspend();
581         if (pm_wakeup_pending()) {
582                 error = -EAGAIN;
583                 goto Power_up;
584         }
585 
586         hibernation_ops->enter();
587         /* We should never get here */
588         while (1);
589 
590  Power_up:
591         syscore_resume();
592         system_state = SYSTEM_RUNNING;
593         local_irq_enable();
594 
595  Enable_cpus:
596         suspend_enable_secondary_cpus();
597 
598  Platform_finish:
599         hibernation_ops->finish();
600 
601         dpm_resume_start(PMSG_RESTORE);
602 
603  Resume_devices:
604         entering_platform_hibernation = false;
605         dpm_resume_end(PMSG_RESTORE);
606         resume_console();
607 
608  Close:
609         hibernation_ops->end();
610 
611         return error;
612 }
613 
614 /**
615  * power_down - Shut the machine down for hibernation.
616  *
617  * Use the platform driver, if configured, to put the system into the sleep
618  * state corresponding to hibernation, or try to power it off or reboot,
619  * depending on the value of hibernation_mode.
620  */
621 static void power_down(void)
622 {
623 #ifdef CONFIG_SUSPEND
624         int error;
625 
626         if (hibernation_mode == HIBERNATION_SUSPEND) {
627                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
628                 if (error) {
629                         hibernation_mode = hibernation_ops ?
630                                                 HIBERNATION_PLATFORM :
631                                                 HIBERNATION_SHUTDOWN;
632                 } else {
633                         /* Restore swap signature. */
634                         error = swsusp_unmark();
635                         if (error)
636                                 pr_err("Swap will be unusable! Try swapon -a.\n");
637 
638                         return;
639                 }
640         }
641 #endif
642 
643         switch (hibernation_mode) {
644         case HIBERNATION_REBOOT:
645                 kernel_restart(NULL);
646                 break;
647         case HIBERNATION_PLATFORM:
648                 hibernation_platform_enter();
649                 /* Fall through */
650         case HIBERNATION_SHUTDOWN:
651                 if (pm_power_off)
652                         kernel_power_off();
653                 break;
654         }
655         kernel_halt();
656         /*
657          * Valid image is on the disk, if we continue we risk serious data
658          * corruption after resume.
659          */
660         pr_crit("Power down manually\n");
661         while (1)
662                 cpu_relax();
663 }
664 
665 static int load_image_and_restore(void)
666 {
667         int error;
668         unsigned int flags;
669 
670         pm_pr_dbg("Loading hibernation image.\n");
671 
672         lock_device_hotplug();
673         error = create_basic_memory_bitmaps();
674         if (error)
675                 goto Unlock;
676 
677         error = swsusp_read(&flags);
678         swsusp_close(FMODE_READ);
679         if (!error)
680                 hibernation_restore(flags & SF_PLATFORM_MODE);
681 
682         pr_err("Failed to load hibernation image, recovering.\n");
683         swsusp_free();
684         free_basic_memory_bitmaps();
685  Unlock:
686         unlock_device_hotplug();
687 
688         return error;
689 }
690 
691 /**
692  * hibernate - Carry out system hibernation, including saving the image.
693  */
694 int hibernate(void)
695 {
696         int error, nr_calls = 0;
697         bool snapshot_test = false;
698 
699         if (!hibernation_available()) {
700                 pm_pr_dbg("Hibernation not available.\n");
701                 return -EPERM;
702         }
703 
704         lock_system_sleep();
705         /* The snapshot device should not be opened while we're running */
706         if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
707                 error = -EBUSY;
708                 goto Unlock;
709         }
710 
711         pr_info("hibernation entry\n");
712         pm_prepare_console();
713         error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
714         if (error) {
715                 nr_calls--;
716                 goto Exit;
717         }
718 
719         ksys_sync_helper();
720 
721         error = freeze_processes();
722         if (error)
723                 goto Exit;
724 
725         lock_device_hotplug();
726         /* Allocate memory management structures */
727         error = create_basic_memory_bitmaps();
728         if (error)
729                 goto Thaw;
730 
731         error = hibernation_snapshot(hibernation_mode == HIBERNATION_PLATFORM);
732         if (error || freezer_test_done)
733                 goto Free_bitmaps;
734 
735         if (in_suspend) {
736                 unsigned int flags = 0;
737 
738                 if (hibernation_mode == HIBERNATION_PLATFORM)
739                         flags |= SF_PLATFORM_MODE;
740                 if (nocompress)
741                         flags |= SF_NOCOMPRESS_MODE;
742                 else
743                         flags |= SF_CRC32_MODE;
744 
745                 pm_pr_dbg("Writing image.\n");
746                 error = swsusp_write(flags);
747                 swsusp_free();
748                 if (!error) {
749                         if (hibernation_mode == HIBERNATION_TEST_RESUME)
750                                 snapshot_test = true;
751                         else
752                                 power_down();
753                 }
754                 in_suspend = 0;
755                 pm_restore_gfp_mask();
756         } else {
757                 pm_pr_dbg("Image restored successfully.\n");
758         }
759 
760  Free_bitmaps:
761         free_basic_memory_bitmaps();
762  Thaw:
763         unlock_device_hotplug();
764         if (snapshot_test) {
765                 pm_pr_dbg("Checking hibernation image\n");
766                 error = swsusp_check();
767                 if (!error)
768                         error = load_image_and_restore();
769         }
770         thaw_processes();
771 
772         /* Don't bother checking whether freezer_test_done is true */
773         freezer_test_done = false;
774  Exit:
775         __pm_notifier_call_chain(PM_POST_HIBERNATION, nr_calls, NULL);
776         pm_restore_console();
777         atomic_inc(&snapshot_device_available);
778  Unlock:
779         unlock_system_sleep();
780         pr_info("hibernation exit\n");
781 
782         return error;
783 }
784 
785 
786 /**
787  * software_resume - Resume from a saved hibernation image.
788  *
789  * This routine is called as a late initcall, when all devices have been
790  * discovered and initialized already.
791  *
792  * The image reading code is called to see if there is a hibernation image
793  * available for reading.  If that is the case, devices are quiesced and the
794  * contents of memory is restored from the saved image.
795  *
796  * If this is successful, control reappears in the restored target kernel in
797  * hibernation_snapshot() which returns to hibernate().  Otherwise, the routine
798  * attempts to recover gracefully and make the kernel return to the normal mode
799  * of operation.
800  */
801 static int software_resume(void)
802 {
803         int error, nr_calls = 0;
804 
805         /*
806          * If the user said "noresume".. bail out early.
807          */
808         if (noresume || !hibernation_available())
809                 return 0;
810 
811         /*
812          * name_to_dev_t() below takes a sysfs buffer mutex when sysfs
813          * is configured into the kernel. Since the regular hibernate
814          * trigger path is via sysfs which takes a buffer mutex before
815          * calling hibernate functions (which take system_transition_mutex)
816          * this can cause lockdep to complain about a possible ABBA deadlock
817          * which cannot happen since we're in the boot code here and
818          * sysfs can't be invoked yet. Therefore, we use a subclass
819          * here to avoid lockdep complaining.
820          */
821         mutex_lock_nested(&system_transition_mutex, SINGLE_DEPTH_NESTING);
822 
823         if (swsusp_resume_device)
824                 goto Check_image;
825 
826         if (!strlen(resume_file)) {
827                 error = -ENOENT;
828                 goto Unlock;
829         }
830 
831         pm_pr_dbg("Checking hibernation image partition %s\n", resume_file);
832 
833         if (resume_delay) {
834                 pr_info("Waiting %dsec before reading resume device ...\n",
835                         resume_delay);
836                 ssleep(resume_delay);
837         }
838 
839         /* Check if the device is there */
840         swsusp_resume_device = name_to_dev_t(resume_file);
841 
842         /*
843          * name_to_dev_t is ineffective to verify parition if resume_file is in
844          * integer format. (e.g. major:minor)
845          */
846         if (isdigit(resume_file[0]) && resume_wait) {
847                 int partno;
848                 while (!get_gendisk(swsusp_resume_device, &partno))
849                         msleep(10);
850         }
851 
852         if (!swsusp_resume_device) {
853                 /*
854                  * Some device discovery might still be in progress; we need
855                  * to wait for this to finish.
856                  */
857                 wait_for_device_probe();
858 
859                 if (resume_wait) {
860                         while ((swsusp_resume_device = name_to_dev_t(resume_file)) == 0)
861                                 msleep(10);
862                         async_synchronize_full();
863                 }
864 
865                 swsusp_resume_device = name_to_dev_t(resume_file);
866                 if (!swsusp_resume_device) {
867                         error = -ENODEV;
868                         goto Unlock;
869                 }
870         }
871 
872  Check_image:
873         pm_pr_dbg("Hibernation image partition %d:%d present\n",
874                 MAJOR(swsusp_resume_device), MINOR(swsusp_resume_device));
875 
876         pm_pr_dbg("Looking for hibernation image.\n");
877         error = swsusp_check();
878         if (error)
879                 goto Unlock;
880 
881         /* The snapshot device should not be opened while we're running */
882         if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
883                 error = -EBUSY;
884                 swsusp_close(FMODE_READ);
885                 goto Unlock;
886         }
887 
888         pr_info("resume from hibernation\n");
889         pm_prepare_console();
890         error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls);
891         if (error) {
892                 nr_calls--;
893                 goto Close_Finish;
894         }
895 
896         pm_pr_dbg("Preparing processes for restore.\n");
897         error = freeze_processes();
898         if (error)
899                 goto Close_Finish;
900         error = load_image_and_restore();
901         thaw_processes();
902  Finish:
903         __pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
904         pm_restore_console();
905         pr_info("resume from hibernation failed (%d)\n", error);
906         atomic_inc(&snapshot_device_available);
907         /* For success case, the suspend path will release the lock */
908  Unlock:
909         mutex_unlock(&system_transition_mutex);
910         pm_pr_dbg("Hibernation image not present or could not be loaded.\n");
911         return error;
912  Close_Finish:
913         swsusp_close(FMODE_READ);
914         goto Finish;
915 }
916 
917 late_initcall_sync(software_resume);
918 
919 
920 static const char * const hibernation_modes[] = {
921         [HIBERNATION_PLATFORM]  = "platform",
922         [HIBERNATION_SHUTDOWN]  = "shutdown",
923         [HIBERNATION_REBOOT]    = "reboot",
924 #ifdef CONFIG_SUSPEND
925         [HIBERNATION_SUSPEND]   = "suspend",
926 #endif
927         [HIBERNATION_TEST_RESUME]       = "test_resume",
928 };
929 
930 /*
931  * /sys/power/disk - Control hibernation mode.
932  *
933  * Hibernation can be handled in several ways.  There are a few different ways
934  * to put the system into the sleep state: using the platform driver (e.g. ACPI
935  * or other hibernation_ops), powering it off or rebooting it (for testing
936  * mostly).
937  *
938  * The sysfs file /sys/power/disk provides an interface for selecting the
939  * hibernation mode to use.  Reading from this file causes the available modes
940  * to be printed.  There are 3 modes that can be supported:
941  *
942  *      'platform'
943  *      'shutdown'
944  *      'reboot'
945  *
946  * If a platform hibernation driver is in use, 'platform' will be supported
947  * and will be used by default.  Otherwise, 'shutdown' will be used by default.
948  * The selected option (i.e. the one corresponding to the current value of
949  * hibernation_mode) is enclosed by a square bracket.
950  *
951  * To select a given hibernation mode it is necessary to write the mode's
952  * string representation (as returned by reading from /sys/power/disk) back
953  * into /sys/power/disk.
954  */
955 
956 static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
957                          char *buf)
958 {
959         int i;
960         char *start = buf;
961 
962         if (!hibernation_available())
963                 return sprintf(buf, "[disabled]\n");
964 
965         for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
966                 if (!hibernation_modes[i])
967                         continue;
968                 switch (i) {
969                 case HIBERNATION_SHUTDOWN:
970                 case HIBERNATION_REBOOT:
971 #ifdef CONFIG_SUSPEND
972                 case HIBERNATION_SUSPEND:
973 #endif
974                 case HIBERNATION_TEST_RESUME:
975                         break;
976                 case HIBERNATION_PLATFORM:
977                         if (hibernation_ops)
978                                 break;
979                         /* not a valid mode, continue with loop */
980                         continue;
981                 }
982                 if (i == hibernation_mode)
983                         buf += sprintf(buf, "[%s] ", hibernation_modes[i]);
984                 else
985                         buf += sprintf(buf, "%s ", hibernation_modes[i]);
986         }
987         buf += sprintf(buf, "\n");
988         return buf-start;
989 }
990 
991 static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
992                           const char *buf, size_t n)
993 {
994         int error = 0;
995         int i;
996         int len;
997         char *p;
998         int mode = HIBERNATION_INVALID;
999 
1000         if (!hibernation_available())
1001                 return -EPERM;
1002 
1003         p = memchr(buf, '\n', n);
1004         len = p ? p - buf : n;
1005 
1006         lock_system_sleep();
1007         for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
1008                 if (len == strlen(hibernation_modes[i])
1009                     && !strncmp(buf, hibernation_modes[i], len)) {
1010                         mode = i;
1011                         break;
1012                 }
1013         }
1014         if (mode != HIBERNATION_INVALID) {
1015                 switch (mode) {
1016                 case HIBERNATION_SHUTDOWN:
1017                 case HIBERNATION_REBOOT:
1018 #ifdef CONFIG_SUSPEND
1019                 case HIBERNATION_SUSPEND:
1020 #endif
1021                 case HIBERNATION_TEST_RESUME:
1022                         hibernation_mode = mode;
1023                         break;
1024                 case HIBERNATION_PLATFORM:
1025                         if (hibernation_ops)
1026                                 hibernation_mode = mode;
1027                         else
1028                                 error = -EINVAL;
1029                 }
1030         } else
1031                 error = -EINVAL;
1032 
1033         if (!error)
1034                 pm_pr_dbg("Hibernation mode set to '%s'\n",
1035                                hibernation_modes[mode]);
1036         unlock_system_sleep();
1037         return error ? error : n;
1038 }
1039 
1040 power_attr(disk);
1041 
1042 static ssize_t resume_show(struct kobject *kobj, struct kobj_attribute *attr,
1043                            char *buf)
1044 {
1045         return sprintf(buf,"%d:%d\n", MAJOR(swsusp_resume_device),
1046                        MINOR(swsusp_resume_device));
1047 }
1048 
1049 static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
1050                             const char *buf, size_t n)
1051 {
1052         dev_t res;
1053         int len = n;
1054         char *name;
1055 
1056         if (len && buf[len-1] == '\n')
1057                 len--;
1058         name = kstrndup(buf, len, GFP_KERNEL);
1059         if (!name)
1060                 return -ENOMEM;
1061 
1062         res = name_to_dev_t(name);
1063         kfree(name);
1064         if (!res)
1065                 return -EINVAL;
1066 
1067         lock_system_sleep();
1068         swsusp_resume_device = res;
1069         unlock_system_sleep();
1070         pm_pr_dbg("Configured resume from disk to %u\n", swsusp_resume_device);
1071         noresume = 0;
1072         software_resume();
1073         return n;
1074 }
1075 
1076 power_attr(resume);
1077 
1078 static ssize_t resume_offset_show(struct kobject *kobj,
1079                                   struct kobj_attribute *attr, char *buf)
1080 {
1081         return sprintf(buf, "%llu\n", (unsigned long long)swsusp_resume_block);
1082 }
1083 
1084 static ssize_t resume_offset_store(struct kobject *kobj,
1085                                    struct kobj_attribute *attr, const char *buf,
1086                                    size_t n)
1087 {
1088         unsigned long long offset;
1089         int rc;
1090 
1091         rc = kstrtoull(buf, 0, &offset);
1092         if (rc)
1093                 return rc;
1094         swsusp_resume_block = offset;
1095 
1096         return n;
1097 }
1098 
1099 power_attr(resume_offset);
1100 
1101 static ssize_t image_size_show(struct kobject *kobj, struct kobj_attribute *attr,
1102                                char *buf)
1103 {
1104         return sprintf(buf, "%lu\n", image_size);
1105 }
1106 
1107 static ssize_t image_size_store(struct kobject *kobj, struct kobj_attribute *attr,
1108                                 const char *buf, size_t n)
1109 {
1110         unsigned long size;
1111 
1112         if (sscanf(buf, "%lu", &size) == 1) {
1113                 image_size = size;
1114                 return n;
1115         }
1116 
1117         return -EINVAL;
1118 }
1119 
1120 power_attr(image_size);
1121 
1122 static ssize_t reserved_size_show(struct kobject *kobj,
1123                                   struct kobj_attribute *attr, char *buf)
1124 {
1125         return sprintf(buf, "%lu\n", reserved_size);
1126 }
1127 
1128 static ssize_t reserved_size_store(struct kobject *kobj,
1129                                    struct kobj_attribute *attr,
1130                                    const char *buf, size_t n)
1131 {
1132         unsigned long size;
1133 
1134         if (sscanf(buf, "%lu", &size) == 1) {
1135                 reserved_size = size;
1136                 return n;
1137         }
1138 
1139         return -EINVAL;
1140 }
1141 
1142 power_attr(reserved_size);
1143 
1144 static struct attribute * g[] = {
1145         &disk_attr.attr,
1146         &resume_offset_attr.attr,
1147         &resume_attr.attr,
1148         &image_size_attr.attr,
1149         &reserved_size_attr.attr,
1150         NULL,
1151 };
1152 
1153 
1154 static const struct attribute_group attr_group = {
1155         .attrs = g,
1156 };
1157 
1158 
1159 static int __init pm_disk_init(void)
1160 {
1161         return sysfs_create_group(power_kobj, &attr_group);
1162 }
1163 
1164 core_initcall(pm_disk_init);
1165 
1166 
1167 static int __init resume_setup(char *str)
1168 {
1169         if (noresume)
1170                 return 1;
1171 
1172         strncpy( resume_file, str, 255 );
1173         return 1;
1174 }
1175 
1176 static int __init resume_offset_setup(char *str)
1177 {
1178         unsigned long long offset;
1179 
1180         if (noresume)
1181                 return 1;
1182 
1183         if (sscanf(str, "%llu", &offset) == 1)
1184                 swsusp_resume_block = offset;
1185 
1186         return 1;
1187 }
1188 
1189 static int __init hibernate_setup(char *str)
1190 {
1191         if (!strncmp(str, "noresume", 8)) {
1192                 noresume = 1;
1193         } else if (!strncmp(str, "nocompress", 10)) {
1194                 nocompress = 1;
1195         } else if (!strncmp(str, "no", 2)) {
1196                 noresume = 1;
1197                 nohibernate = 1;
1198         } else if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)
1199                    && !strncmp(str, "protect_image", 13)) {
1200                 enable_restore_image_protection();
1201         }
1202         return 1;
1203 }
1204 
1205 static int __init noresume_setup(char *str)
1206 {
1207         noresume = 1;
1208         return 1;
1209 }
1210 
1211 static int __init resumewait_setup(char *str)
1212 {
1213         resume_wait = 1;
1214         return 1;
1215 }
1216 
1217 static int __init resumedelay_setup(char *str)
1218 {
1219         int rc = kstrtouint(str, 0, &resume_delay);
1220 
1221         if (rc)
1222                 return rc;
1223         return 1;
1224 }
1225 
1226 static int __init nohibernate_setup(char *str)
1227 {
1228         noresume = 1;
1229         nohibernate = 1;
1230         return 1;
1231 }
1232 
1233 __setup("noresume", noresume_setup);
1234 __setup("resume_offset=", resume_offset_setup);
1235 __setup("resume=", resume_setup);
1236 __setup("hibernate=", hibernate_setup);
1237 __setup("resumewait", resumewait_setup);
1238 __setup("resumedelay=", resumedelay_setup);
1239 __setup("nohibernate", nohibernate_setup);
1240 

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