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

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  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 __weak int arch_resume_nosmt(void)
262 {
263         return 0;
264 }
265 
266 /**
267  * create_image - Create a hibernation image.
268  * @platform_mode: Whether or not to use the platform driver.
269  *
270  * Execute device drivers' "late" and "noirq" freeze callbacks, create a
271  * hibernation image and run the drivers' "noirq" and "early" thaw callbacks.
272  *
273  * Control reappears in this routine after the subsequent restore.
274  */
275 static int create_image(int platform_mode)
276 {
277         int error;
278 
279         error = dpm_suspend_end(PMSG_FREEZE);
280         if (error) {
281                 pr_err("Some devices failed to power down, aborting hibernation\n");
282                 return error;
283         }
284 
285         error = platform_pre_snapshot(platform_mode);
286         if (error || hibernation_test(TEST_PLATFORM))
287                 goto Platform_finish;
288 
289         error = disable_nonboot_cpus();
290         if (error || hibernation_test(TEST_CPUS))
291                 goto Enable_cpus;
292 
293         local_irq_disable();
294 
295         system_state = SYSTEM_SUSPEND;
296 
297         error = syscore_suspend();
298         if (error) {
299                 pr_err("Some system devices failed to power down, aborting hibernation\n");
300                 goto Enable_irqs;
301         }
302 
303         if (hibernation_test(TEST_CORE) || pm_wakeup_pending())
304                 goto Power_up;
305 
306         in_suspend = 1;
307         save_processor_state();
308         trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, true);
309         error = swsusp_arch_suspend();
310         /* Restore control flow magically appears here */
311         restore_processor_state();
312         trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, false);
313         if (error)
314                 pr_err("Error %d creating hibernation image\n", error);
315 
316         if (!in_suspend) {
317                 events_check_enabled = false;
318                 clear_free_pages();
319         }
320 
321         platform_leave(platform_mode);
322 
323  Power_up:
324         syscore_resume();
325 
326  Enable_irqs:
327         system_state = SYSTEM_RUNNING;
328         local_irq_enable();
329 
330  Enable_cpus:
331         enable_nonboot_cpus();
332 
333         /* Allow architectures to do nosmt-specific post-resume dances */
334         if (!in_suspend)
335                 error = arch_resume_nosmt();
336 
337  Platform_finish:
338         platform_finish(platform_mode);
339 
340         dpm_resume_start(in_suspend ?
341                 (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
342 
343         return error;
344 }
345 
346 /**
347  * hibernation_snapshot - Quiesce devices and create a hibernation image.
348  * @platform_mode: If set, use platform driver to prepare for the transition.
349  *
350  * This routine must be called with system_transition_mutex held.
351  */
352 int hibernation_snapshot(int platform_mode)
353 {
354         pm_message_t msg;
355         int error;
356 
357         pm_suspend_clear_flags();
358         error = platform_begin(platform_mode);
359         if (error)
360                 goto Close;
361 
362         /* Preallocate image memory before shutting down devices. */
363         error = hibernate_preallocate_memory();
364         if (error)
365                 goto Close;
366 
367         error = freeze_kernel_threads();
368         if (error)
369                 goto Cleanup;
370 
371         if (hibernation_test(TEST_FREEZER)) {
372 
373                 /*
374                  * Indicate to the caller that we are returning due to a
375                  * successful freezer test.
376                  */
377                 freezer_test_done = true;
378                 goto Thaw;
379         }
380 
381         error = dpm_prepare(PMSG_FREEZE);
382         if (error) {
383                 dpm_complete(PMSG_RECOVER);
384                 goto Thaw;
385         }
386 
387         suspend_console();
388         pm_restrict_gfp_mask();
389 
390         error = dpm_suspend(PMSG_FREEZE);
391 
392         if (error || hibernation_test(TEST_DEVICES))
393                 platform_recover(platform_mode);
394         else
395                 error = create_image(platform_mode);
396 
397         /*
398          * In the case that we call create_image() above, the control
399          * returns here (1) after the image has been created or the
400          * image creation has failed and (2) after a successful restore.
401          */
402 
403         /* We may need to release the preallocated image pages here. */
404         if (error || !in_suspend)
405                 swsusp_free();
406 
407         msg = in_suspend ? (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE;
408         dpm_resume(msg);
409 
410         if (error || !in_suspend)
411                 pm_restore_gfp_mask();
412 
413         resume_console();
414         dpm_complete(msg);
415 
416  Close:
417         platform_end(platform_mode);
418         return error;
419 
420  Thaw:
421         thaw_kernel_threads();
422  Cleanup:
423         swsusp_free();
424         goto Close;
425 }
426 
427 int __weak hibernate_resume_nonboot_cpu_disable(void)
428 {
429         return disable_nonboot_cpus();
430 }
431 
432 /**
433  * resume_target_kernel - Restore system state from a hibernation image.
434  * @platform_mode: Whether or not to use the platform driver.
435  *
436  * Execute device drivers' "noirq" and "late" freeze callbacks, restore the
437  * contents of highmem that have not been restored yet from the image and run
438  * the low-level code that will restore the remaining contents of memory and
439  * switch to the just restored target kernel.
440  */
441 static int resume_target_kernel(bool platform_mode)
442 {
443         int error;
444 
445         error = dpm_suspend_end(PMSG_QUIESCE);
446         if (error) {
447                 pr_err("Some devices failed to power down, aborting resume\n");
448                 return error;
449         }
450 
451         error = platform_pre_restore(platform_mode);
452         if (error)
453                 goto Cleanup;
454 
455         error = hibernate_resume_nonboot_cpu_disable();
456         if (error)
457                 goto Enable_cpus;
458 
459         local_irq_disable();
460         system_state = SYSTEM_SUSPEND;
461 
462         error = syscore_suspend();
463         if (error)
464                 goto Enable_irqs;
465 
466         save_processor_state();
467         error = restore_highmem();
468         if (!error) {
469                 error = swsusp_arch_resume();
470                 /*
471                  * The code below is only ever reached in case of a failure.
472                  * Otherwise, execution continues at the place where
473                  * swsusp_arch_suspend() was called.
474                  */
475                 BUG_ON(!error);
476                 /*
477                  * This call to restore_highmem() reverts the changes made by
478                  * the previous one.
479                  */
480                 restore_highmem();
481         }
482         /*
483          * The only reason why swsusp_arch_resume() can fail is memory being
484          * very tight, so we have to free it as soon as we can to avoid
485          * subsequent failures.
486          */
487         swsusp_free();
488         restore_processor_state();
489         touch_softlockup_watchdog();
490 
491         syscore_resume();
492 
493  Enable_irqs:
494         system_state = SYSTEM_RUNNING;
495         local_irq_enable();
496 
497  Enable_cpus:
498         enable_nonboot_cpus();
499 
500  Cleanup:
501         platform_restore_cleanup(platform_mode);
502 
503         dpm_resume_start(PMSG_RECOVER);
504 
505         return error;
506 }
507 
508 /**
509  * hibernation_restore - Quiesce devices and restore from a hibernation image.
510  * @platform_mode: If set, use platform driver to prepare for the transition.
511  *
512  * This routine must be called with system_transition_mutex held.  If it is
513  * successful, control reappears in the restored target kernel in
514  * hibernation_snapshot().
515  */
516 int hibernation_restore(int platform_mode)
517 {
518         int error;
519 
520         pm_prepare_console();
521         suspend_console();
522         pm_restrict_gfp_mask();
523         error = dpm_suspend_start(PMSG_QUIESCE);
524         if (!error) {
525                 error = resume_target_kernel(platform_mode);
526                 /*
527                  * The above should either succeed and jump to the new kernel,
528                  * or return with an error. Otherwise things are just
529                  * undefined, so let's be paranoid.
530                  */
531                 BUG_ON(!error);
532         }
533         dpm_resume_end(PMSG_RECOVER);
534         pm_restore_gfp_mask();
535         resume_console();
536         pm_restore_console();
537         return error;
538 }
539 
540 /**
541  * hibernation_platform_enter - Power off the system using the platform driver.
542  */
543 int hibernation_platform_enter(void)
544 {
545         int error;
546 
547         if (!hibernation_ops)
548                 return -ENOSYS;
549 
550         /*
551          * We have cancelled the power transition by running
552          * hibernation_ops->finish() before saving the image, so we should let
553          * the firmware know that we're going to enter the sleep state after all
554          */
555         error = hibernation_ops->begin();
556         if (error)
557                 goto Close;
558 
559         entering_platform_hibernation = true;
560         suspend_console();
561         error = dpm_suspend_start(PMSG_HIBERNATE);
562         if (error) {
563                 if (hibernation_ops->recover)
564                         hibernation_ops->recover();
565                 goto Resume_devices;
566         }
567 
568         error = dpm_suspend_end(PMSG_HIBERNATE);
569         if (error)
570                 goto Resume_devices;
571 
572         error = hibernation_ops->prepare();
573         if (error)
574                 goto Platform_finish;
575 
576         error = disable_nonboot_cpus();
577         if (error)
578                 goto Enable_cpus;
579 
580         local_irq_disable();
581         system_state = SYSTEM_SUSPEND;
582         syscore_suspend();
583         if (pm_wakeup_pending()) {
584                 error = -EAGAIN;
585                 goto Power_up;
586         }
587 
588         hibernation_ops->enter();
589         /* We should never get here */
590         while (1);
591 
592  Power_up:
593         syscore_resume();
594         system_state = SYSTEM_RUNNING;
595         local_irq_enable();
596 
597  Enable_cpus:
598         enable_nonboot_cpus();
599 
600  Platform_finish:
601         hibernation_ops->finish();
602 
603         dpm_resume_start(PMSG_RESTORE);
604 
605  Resume_devices:
606         entering_platform_hibernation = false;
607         dpm_resume_end(PMSG_RESTORE);
608         resume_console();
609 
610  Close:
611         hibernation_ops->end();
612 
613         return error;
614 }
615 
616 /**
617  * power_down - Shut the machine down for hibernation.
618  *
619  * Use the platform driver, if configured, to put the system into the sleep
620  * state corresponding to hibernation, or try to power it off or reboot,
621  * depending on the value of hibernation_mode.
622  */
623 static void power_down(void)
624 {
625 #ifdef CONFIG_SUSPEND
626         int error;
627 
628         if (hibernation_mode == HIBERNATION_SUSPEND) {
629                 error = suspend_devices_and_enter(PM_SUSPEND_MEM);
630                 if (error) {
631                         hibernation_mode = hibernation_ops ?
632                                                 HIBERNATION_PLATFORM :
633                                                 HIBERNATION_SHUTDOWN;
634                 } else {
635                         /* Restore swap signature. */
636                         error = swsusp_unmark();
637                         if (error)
638                                 pr_err("Swap will be unusable! Try swapon -a.\n");
639 
640                         return;
641                 }
642         }
643 #endif
644 
645         switch (hibernation_mode) {
646         case HIBERNATION_REBOOT:
647                 kernel_restart(NULL);
648                 break;
649         case HIBERNATION_PLATFORM:
650                 hibernation_platform_enter();
651                 /* Fall through */
652         case HIBERNATION_SHUTDOWN:
653                 if (pm_power_off)
654                         kernel_power_off();
655                 break;
656         }
657         kernel_halt();
658         /*
659          * Valid image is on the disk, if we continue we risk serious data
660          * corruption after resume.
661          */
662         pr_crit("Power down manually\n");
663         while (1)
664                 cpu_relax();
665 }
666 
667 static int load_image_and_restore(void)
668 {
669         int error;
670         unsigned int flags;
671 
672         pm_pr_dbg("Loading hibernation image.\n");
673 
674         lock_device_hotplug();
675         error = create_basic_memory_bitmaps();
676         if (error)
677                 goto Unlock;
678 
679         error = swsusp_read(&flags);
680         swsusp_close(FMODE_READ);
681         if (!error)
682                 hibernation_restore(flags & SF_PLATFORM_MODE);
683 
684         pr_err("Failed to load hibernation image, recovering.\n");
685         swsusp_free();
686         free_basic_memory_bitmaps();
687  Unlock:
688         unlock_device_hotplug();
689 
690         return error;
691 }
692 
693 /**
694  * hibernate - Carry out system hibernation, including saving the image.
695  */
696 int hibernate(void)
697 {
698         int error, nr_calls = 0;
699         bool snapshot_test = false;
700 
701         if (!hibernation_available()) {
702                 pm_pr_dbg("Hibernation not available.\n");
703                 return -EPERM;
704         }
705 
706         lock_system_sleep();
707         /* The snapshot device should not be opened while we're running */
708         if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
709                 error = -EBUSY;
710                 goto Unlock;
711         }
712 
713         pr_info("hibernation entry\n");
714         pm_prepare_console();
715         error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
716         if (error) {
717                 nr_calls--;
718                 goto Exit;
719         }
720 
721         pr_info("Syncing filesystems ... \n");
722         ksys_sync();
723         pr_info("done.\n");
724 
725         error = freeze_processes();
726         if (error)
727                 goto Exit;
728 
729         lock_device_hotplug();
730         /* Allocate memory management structures */
731         error = create_basic_memory_bitmaps();
732         if (error)
733                 goto Thaw;
734 
735         error = hibernation_snapshot(hibernation_mode == HIBERNATION_PLATFORM);
736         if (error || freezer_test_done)
737                 goto Free_bitmaps;
738 
739         if (in_suspend) {
740                 unsigned int flags = 0;
741 
742                 if (hibernation_mode == HIBERNATION_PLATFORM)
743                         flags |= SF_PLATFORM_MODE;
744                 if (nocompress)
745                         flags |= SF_NOCOMPRESS_MODE;
746                 else
747                         flags |= SF_CRC32_MODE;
748 
749                 pm_pr_dbg("Writing image.\n");
750                 error = swsusp_write(flags);
751                 swsusp_free();
752                 if (!error) {
753                         if (hibernation_mode == HIBERNATION_TEST_RESUME)
754                                 snapshot_test = true;
755                         else
756                                 power_down();
757                 }
758                 in_suspend = 0;
759                 pm_restore_gfp_mask();
760         } else {
761                 pm_pr_dbg("Image restored successfully.\n");
762         }
763 
764  Free_bitmaps:
765         free_basic_memory_bitmaps();
766  Thaw:
767         unlock_device_hotplug();
768         if (snapshot_test) {
769                 pm_pr_dbg("Checking hibernation image\n");
770                 error = swsusp_check();
771                 if (!error)
772                         error = load_image_and_restore();
773         }
774         thaw_processes();
775 
776         /* Don't bother checking whether freezer_test_done is true */
777         freezer_test_done = false;
778  Exit:
779         __pm_notifier_call_chain(PM_POST_HIBERNATION, nr_calls, NULL);
780         pm_restore_console();
781         atomic_inc(&snapshot_device_available);
782  Unlock:
783         unlock_system_sleep();
784         pr_info("hibernation exit\n");
785 
786         return error;
787 }
788 
789 
790 /**
791  * software_resume - Resume from a saved hibernation image.
792  *
793  * This routine is called as a late initcall, when all devices have been
794  * discovered and initialized already.
795  *
796  * The image reading code is called to see if there is a hibernation image
797  * available for reading.  If that is the case, devices are quiesced and the
798  * contents of memory is restored from the saved image.
799  *
800  * If this is successful, control reappears in the restored target kernel in
801  * hibernation_snapshot() which returns to hibernate().  Otherwise, the routine
802  * attempts to recover gracefully and make the kernel return to the normal mode
803  * of operation.
804  */
805 static int software_resume(void)
806 {
807         int error, nr_calls = 0;
808 
809         /*
810          * If the user said "noresume".. bail out early.
811          */
812         if (noresume || !hibernation_available())
813                 return 0;
814 
815         /*
816          * name_to_dev_t() below takes a sysfs buffer mutex when sysfs
817          * is configured into the kernel. Since the regular hibernate
818          * trigger path is via sysfs which takes a buffer mutex before
819          * calling hibernate functions (which take system_transition_mutex)
820          * this can cause lockdep to complain about a possible ABBA deadlock
821          * which cannot happen since we're in the boot code here and
822          * sysfs can't be invoked yet. Therefore, we use a subclass
823          * here to avoid lockdep complaining.
824          */
825         mutex_lock_nested(&system_transition_mutex, SINGLE_DEPTH_NESTING);
826 
827         if (swsusp_resume_device)
828                 goto Check_image;
829 
830         if (!strlen(resume_file)) {
831                 error = -ENOENT;
832                 goto Unlock;
833         }
834 
835         pm_pr_dbg("Checking hibernation image partition %s\n", resume_file);
836 
837         if (resume_delay) {
838                 pr_info("Waiting %dsec before reading resume device ...\n",
839                         resume_delay);
840                 ssleep(resume_delay);
841         }
842 
843         /* Check if the device is there */
844         swsusp_resume_device = name_to_dev_t(resume_file);
845 
846         /*
847          * name_to_dev_t is ineffective to verify parition if resume_file is in
848          * integer format. (e.g. major:minor)
849          */
850         if (isdigit(resume_file[0]) && resume_wait) {
851                 int partno;
852                 while (!get_gendisk(swsusp_resume_device, &partno))
853                         msleep(10);
854         }
855 
856         if (!swsusp_resume_device) {
857                 /*
858                  * Some device discovery might still be in progress; we need
859                  * to wait for this to finish.
860                  */
861                 wait_for_device_probe();
862 
863                 if (resume_wait) {
864                         while ((swsusp_resume_device = name_to_dev_t(resume_file)) == 0)
865                                 msleep(10);
866                         async_synchronize_full();
867                 }
868 
869                 swsusp_resume_device = name_to_dev_t(resume_file);
870                 if (!swsusp_resume_device) {
871                         error = -ENODEV;
872                         goto Unlock;
873                 }
874         }
875 
876  Check_image:
877         pm_pr_dbg("Hibernation image partition %d:%d present\n",
878                 MAJOR(swsusp_resume_device), MINOR(swsusp_resume_device));
879 
880         pm_pr_dbg("Looking for hibernation image.\n");
881         error = swsusp_check();
882         if (error)
883                 goto Unlock;
884 
885         /* The snapshot device should not be opened while we're running */
886         if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
887                 error = -EBUSY;
888                 swsusp_close(FMODE_READ);
889                 goto Unlock;
890         }
891 
892         pr_info("resume from hibernation\n");
893         pm_prepare_console();
894         error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls);
895         if (error) {
896                 nr_calls--;
897                 goto Close_Finish;
898         }
899 
900         pm_pr_dbg("Preparing processes for restore.\n");
901         error = freeze_processes();
902         if (error)
903                 goto Close_Finish;
904         error = load_image_and_restore();
905         thaw_processes();
906  Finish:
907         __pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
908         pm_restore_console();
909         pr_info("resume from hibernation failed (%d)\n", error);
910         atomic_inc(&snapshot_device_available);
911         /* For success case, the suspend path will release the lock */
912  Unlock:
913         mutex_unlock(&system_transition_mutex);
914         pm_pr_dbg("Hibernation image not present or could not be loaded.\n");
915         return error;
916  Close_Finish:
917         swsusp_close(FMODE_READ);
918         goto Finish;
919 }
920 
921 late_initcall_sync(software_resume);
922 
923 
924 static const char * const hibernation_modes[] = {
925         [HIBERNATION_PLATFORM]  = "platform",
926         [HIBERNATION_SHUTDOWN]  = "shutdown",
927         [HIBERNATION_REBOOT]    = "reboot",
928 #ifdef CONFIG_SUSPEND
929         [HIBERNATION_SUSPEND]   = "suspend",
930 #endif
931         [HIBERNATION_TEST_RESUME]       = "test_resume",
932 };
933 
934 /*
935  * /sys/power/disk - Control hibernation mode.
936  *
937  * Hibernation can be handled in several ways.  There are a few different ways
938  * to put the system into the sleep state: using the platform driver (e.g. ACPI
939  * or other hibernation_ops), powering it off or rebooting it (for testing
940  * mostly).
941  *
942  * The sysfs file /sys/power/disk provides an interface for selecting the
943  * hibernation mode to use.  Reading from this file causes the available modes
944  * to be printed.  There are 3 modes that can be supported:
945  *
946  *      'platform'
947  *      'shutdown'
948  *      'reboot'
949  *
950  * If a platform hibernation driver is in use, 'platform' will be supported
951  * and will be used by default.  Otherwise, 'shutdown' will be used by default.
952  * The selected option (i.e. the one corresponding to the current value of
953  * hibernation_mode) is enclosed by a square bracket.
954  *
955  * To select a given hibernation mode it is necessary to write the mode's
956  * string representation (as returned by reading from /sys/power/disk) back
957  * into /sys/power/disk.
958  */
959 
960 static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
961                          char *buf)
962 {
963         int i;
964         char *start = buf;
965 
966         if (!hibernation_available())
967                 return sprintf(buf, "[disabled]\n");
968 
969         for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
970                 if (!hibernation_modes[i])
971                         continue;
972                 switch (i) {
973                 case HIBERNATION_SHUTDOWN:
974                 case HIBERNATION_REBOOT:
975 #ifdef CONFIG_SUSPEND
976                 case HIBERNATION_SUSPEND:
977 #endif
978                 case HIBERNATION_TEST_RESUME:
979                         break;
980                 case HIBERNATION_PLATFORM:
981                         if (hibernation_ops)
982                                 break;
983                         /* not a valid mode, continue with loop */
984                         continue;
985                 }
986                 if (i == hibernation_mode)
987                         buf += sprintf(buf, "[%s] ", hibernation_modes[i]);
988                 else
989                         buf += sprintf(buf, "%s ", hibernation_modes[i]);
990         }
991         buf += sprintf(buf, "\n");
992         return buf-start;
993 }
994 
995 static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
996                           const char *buf, size_t n)
997 {
998         int error = 0;
999         int i;
1000         int len;
1001         char *p;
1002         int mode = HIBERNATION_INVALID;
1003 
1004         if (!hibernation_available())
1005                 return -EPERM;
1006 
1007         p = memchr(buf, '\n', n);
1008         len = p ? p - buf : n;
1009 
1010         lock_system_sleep();
1011         for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
1012                 if (len == strlen(hibernation_modes[i])
1013                     && !strncmp(buf, hibernation_modes[i], len)) {
1014                         mode = i;
1015                         break;
1016                 }
1017         }
1018         if (mode != HIBERNATION_INVALID) {
1019                 switch (mode) {
1020                 case HIBERNATION_SHUTDOWN:
1021                 case HIBERNATION_REBOOT:
1022 #ifdef CONFIG_SUSPEND
1023                 case HIBERNATION_SUSPEND:
1024 #endif
1025                 case HIBERNATION_TEST_RESUME:
1026                         hibernation_mode = mode;
1027                         break;
1028                 case HIBERNATION_PLATFORM:
1029                         if (hibernation_ops)
1030                                 hibernation_mode = mode;
1031                         else
1032                                 error = -EINVAL;
1033                 }
1034         } else
1035                 error = -EINVAL;
1036 
1037         if (!error)
1038                 pm_pr_dbg("Hibernation mode set to '%s'\n",
1039                                hibernation_modes[mode]);
1040         unlock_system_sleep();
1041         return error ? error : n;
1042 }
1043 
1044 power_attr(disk);
1045 
1046 static ssize_t resume_show(struct kobject *kobj, struct kobj_attribute *attr,
1047                            char *buf)
1048 {
1049         return sprintf(buf,"%d:%d\n", MAJOR(swsusp_resume_device),
1050                        MINOR(swsusp_resume_device));
1051 }
1052 
1053 static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
1054                             const char *buf, size_t n)
1055 {
1056         dev_t res;
1057         int len = n;
1058         char *name;
1059 
1060         if (len && buf[len-1] == '\n')
1061                 len--;
1062         name = kstrndup(buf, len, GFP_KERNEL);
1063         if (!name)
1064                 return -ENOMEM;
1065 
1066         res = name_to_dev_t(name);
1067         kfree(name);
1068         if (!res)
1069                 return -EINVAL;
1070 
1071         lock_system_sleep();
1072         swsusp_resume_device = res;
1073         unlock_system_sleep();
1074         pm_pr_dbg("Configured resume from disk to %u\n", swsusp_resume_device);
1075         noresume = 0;
1076         software_resume();
1077         return n;
1078 }
1079 
1080 power_attr(resume);
1081 
1082 static ssize_t resume_offset_show(struct kobject *kobj,
1083                                   struct kobj_attribute *attr, char *buf)
1084 {
1085         return sprintf(buf, "%llu\n", (unsigned long long)swsusp_resume_block);
1086 }
1087 
1088 static ssize_t resume_offset_store(struct kobject *kobj,
1089                                    struct kobj_attribute *attr, const char *buf,
1090                                    size_t n)
1091 {
1092         unsigned long long offset;
1093         int rc;
1094 
1095         rc = kstrtoull(buf, 0, &offset);
1096         if (rc)
1097                 return rc;
1098         swsusp_resume_block = offset;
1099 
1100         return n;
1101 }
1102 
1103 power_attr(resume_offset);
1104 
1105 static ssize_t image_size_show(struct kobject *kobj, struct kobj_attribute *attr,
1106                                char *buf)
1107 {
1108         return sprintf(buf, "%lu\n", image_size);
1109 }
1110 
1111 static ssize_t image_size_store(struct kobject *kobj, struct kobj_attribute *attr,
1112                                 const char *buf, size_t n)
1113 {
1114         unsigned long size;
1115 
1116         if (sscanf(buf, "%lu", &size) == 1) {
1117                 image_size = size;
1118                 return n;
1119         }
1120 
1121         return -EINVAL;
1122 }
1123 
1124 power_attr(image_size);
1125 
1126 static ssize_t reserved_size_show(struct kobject *kobj,
1127                                   struct kobj_attribute *attr, char *buf)
1128 {
1129         return sprintf(buf, "%lu\n", reserved_size);
1130 }
1131 
1132 static ssize_t reserved_size_store(struct kobject *kobj,
1133                                    struct kobj_attribute *attr,
1134                                    const char *buf, size_t n)
1135 {
1136         unsigned long size;
1137 
1138         if (sscanf(buf, "%lu", &size) == 1) {
1139                 reserved_size = size;
1140                 return n;
1141         }
1142 
1143         return -EINVAL;
1144 }
1145 
1146 power_attr(reserved_size);
1147 
1148 static struct attribute * g[] = {
1149         &disk_attr.attr,
1150         &resume_offset_attr.attr,
1151         &resume_attr.attr,
1152         &image_size_attr.attr,
1153         &reserved_size_attr.attr,
1154         NULL,
1155 };
1156 
1157 
1158 static const struct attribute_group attr_group = {
1159         .attrs = g,
1160 };
1161 
1162 
1163 static int __init pm_disk_init(void)
1164 {
1165         return sysfs_create_group(power_kobj, &attr_group);
1166 }
1167 
1168 core_initcall(pm_disk_init);
1169 
1170 
1171 static int __init resume_setup(char *str)
1172 {
1173         if (noresume)
1174                 return 1;
1175 
1176         strncpy( resume_file, str, 255 );
1177         return 1;
1178 }
1179 
1180 static int __init resume_offset_setup(char *str)
1181 {
1182         unsigned long long offset;
1183 
1184         if (noresume)
1185                 return 1;
1186 
1187         if (sscanf(str, "%llu", &offset) == 1)
1188                 swsusp_resume_block = offset;
1189 
1190         return 1;
1191 }
1192 
1193 static int __init hibernate_setup(char *str)
1194 {
1195         if (!strncmp(str, "noresume", 8)) {
1196                 noresume = 1;
1197         } else if (!strncmp(str, "nocompress", 10)) {
1198                 nocompress = 1;
1199         } else if (!strncmp(str, "no", 2)) {
1200                 noresume = 1;
1201                 nohibernate = 1;
1202         } else if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)
1203                    && !strncmp(str, "protect_image", 13)) {
1204                 enable_restore_image_protection();
1205         }
1206         return 1;
1207 }
1208 
1209 static int __init noresume_setup(char *str)
1210 {
1211         noresume = 1;
1212         return 1;
1213 }
1214 
1215 static int __init resumewait_setup(char *str)
1216 {
1217         resume_wait = 1;
1218         return 1;
1219 }
1220 
1221 static int __init resumedelay_setup(char *str)
1222 {
1223         int rc = kstrtouint(str, 0, &resume_delay);
1224 
1225         if (rc)
1226                 return rc;
1227         return 1;
1228 }
1229 
1230 static int __init nohibernate_setup(char *str)
1231 {
1232         noresume = 1;
1233         nohibernate = 1;
1234         return 1;
1235 }
1236 
1237 __setup("noresume", noresume_setup);
1238 __setup("resume_offset=", resume_offset_setup);
1239 __setup("resume=", resume_setup);
1240 __setup("hibernate=", hibernate_setup);
1241 __setup("resumewait", resumewait_setup);
1242 __setup("resumedelay=", resumedelay_setup);
1243 __setup("nohibernate", nohibernate_setup);
1244 

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