text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * kernel/power/hibernate.c - Hibernation (a.k.a suspend-to-disk) support.
   *
   * Copyright (c) 2003 Patrick Mochel
   * Copyright (c) 2003 Open Source Development Lab
   * Copyright (c) 2004 Pavel Machek <pavel@ucw.cz>
   * Copyright (c) 2009 Rafael J. Wysocki, Novell Inc.
   * Copyright (C) 2012 Bojan Smojver <bojan@rexursive.com>
   */
  
  #define pr_fmt(fmt) "PM: " fmt
  
  #include <linux/export.h>
  #include <linux/suspend.h>
  #include <linux/reboot.h>
  #include <linux/string.h>
  #include <linux/device.h>
  #include <linux/async.h>
  #include <linux/delay.h>
  #include <linux/fs.h>
  #include <linux/mount.h>
  #include <linux/pm.h>
  #include <linux/nmi.h>
  #include <linux/console.h>
  #include <linux/cpu.h>
  #include <linux/freezer.h>
  #include <linux/gfp.h>
  #include <linux/syscore_ops.h>
  #include <linux/ctype.h>
  #include <linux/genhd.h>
  #include <linux/ktime.h>
  #include <trace/events/power.h>
  
  #include "power.h"
  
  
  static int nocompress;
  static int noresume;
  static int nohibernate;
  static int resume_wait;
  static unsigned int resume_delay;
  static char resume_file[256] = CONFIG_PM_STD_PARTITION;
  dev_t swsusp_resume_device;
  sector_t swsusp_resume_block;
  __visible int in_suspend __nosavedata;
  
  enum {
  	HIBERNATION_INVALID,
  	HIBERNATION_PLATFORM,
  	HIBERNATION_SHUTDOWN,
  	HIBERNATION_REBOOT,
  #ifdef CONFIG_SUSPEND
  	HIBERNATION_SUSPEND,
  #endif
  	HIBERNATION_TEST_RESUME,
  	/* keep last */
  	__HIBERNATION_AFTER_LAST
  };
  #define HIBERNATION_MAX (__HIBERNATION_AFTER_LAST-1)
  #define HIBERNATION_FIRST (HIBERNATION_INVALID + 1)
  
  static int hibernation_mode = HIBERNATION_SHUTDOWN;
  
  bool freezer_test_done;
  
  static const struct platform_hibernation_ops *hibernation_ops;
  
  bool hibernation_available(void)
  {
  	return (nohibernate == 0);
  }
  
  /**
   * hibernation_set_ops - Set the global hibernate operations.
   * @ops: Hibernation operations to use in subsequent hibernation transitions.
   */
  void hibernation_set_ops(const struct platform_hibernation_ops *ops)
  {
  	if (ops && !(ops->begin && ops->end &&  ops->pre_snapshot
  	    && ops->prepare && ops->finish && ops->enter && ops->pre_restore
  	    && ops->restore_cleanup && ops->leave)) {
  		WARN_ON(1);
  		return;
  	}
  	lock_system_sleep();
  	hibernation_ops = ops;
  	if (ops)
  		hibernation_mode = HIBERNATION_PLATFORM;
  	else if (hibernation_mode == HIBERNATION_PLATFORM)
  		hibernation_mode = HIBERNATION_SHUTDOWN;
  
  	unlock_system_sleep();
  }
  EXPORT_SYMBOL_GPL(hibernation_set_ops);
  
  static bool entering_platform_hibernation;
  
  bool system_entering_hibernation(void)
  {
  	return entering_platform_hibernation;
  }
  EXPORT_SYMBOL(system_entering_hibernation);
  
  #ifdef CONFIG_PM_DEBUG
  static void hibernation_debug_sleep(void)
  {
  	pr_info("hibernation debug: Waiting for 5 seconds.\n");
  	mdelay(5000);
  }
  
  static int hibernation_test(int level)
  {
  	if (pm_test_level == level) {
  		hibernation_debug_sleep();
  		return 1;
  	}
  	return 0;
  }
  #else /* !CONFIG_PM_DEBUG */
  static int hibernation_test(int level) { return 0; }
  #endif /* !CONFIG_PM_DEBUG */
  
  /**
   * platform_begin - Call platform to start hibernation.
   * @platform_mode: Whether or not to use the platform driver.
   */
  static int platform_begin(int platform_mode)
  {
  	return (platform_mode && hibernation_ops) ?
  		hibernation_ops->begin(PMSG_FREEZE) : 0;
  }
  
  /**
   * platform_end - Call platform to finish transition to the working state.
   * @platform_mode: Whether or not to use the platform driver.
   */
  static void platform_end(int platform_mode)
  {
  	if (platform_mode && hibernation_ops)
  		hibernation_ops->end();
  }
  
  /**
   * platform_pre_snapshot - Call platform to prepare the machine for hibernation.
   * @platform_mode: Whether or not to use the platform driver.
   *
   * Use the platform driver to prepare the system for creating a hibernate image,
   * if so configured, and return an error code if that fails.
   */
  
  static int platform_pre_snapshot(int platform_mode)
  {
  	return (platform_mode && hibernation_ops) ?
  		hibernation_ops->pre_snapshot() : 0;
  }
  
  /**
   * platform_leave - Call platform to prepare a transition to the working state.
   * @platform_mode: Whether or not to use the platform driver.
   *
   * Use the platform driver prepare to prepare the machine for switching to the
   * normal mode of operation.
   *
   * This routine is called on one CPU with interrupts disabled.
   */
  static void platform_leave(int platform_mode)
  {
  	if (platform_mode && hibernation_ops)
  		hibernation_ops->leave();
  }
  
  /**
   * platform_finish - Call platform to switch the system to the working state.
   * @platform_mode: Whether or not to use the platform driver.
   *
   * Use the platform driver to switch the machine to the normal mode of
   * operation.
   *
   * This routine must be called after platform_prepare().
   */
  static void platform_finish(int platform_mode)
  {
  	if (platform_mode && hibernation_ops)
  		hibernation_ops->finish();
  }
  
  /**
   * platform_pre_restore - Prepare for hibernate image restoration.
   * @platform_mode: Whether or not to use the platform driver.
   *
   * Use the platform driver to prepare the system for resume from a hibernation
   * image.
   *
   * If the restore fails after this function has been called,
   * platform_restore_cleanup() must be called.
   */
  static int platform_pre_restore(int platform_mode)
  {
  	return (platform_mode && hibernation_ops) ?
  		hibernation_ops->pre_restore() : 0;
  }
  
  /**
   * platform_restore_cleanup - Switch to the working state after failing restore.
   * @platform_mode: Whether or not to use the platform driver.
   *
   * Use the platform driver to switch the system to the normal mode of operation
   * after a failing restore.
   *
   * If platform_pre_restore() has been called before the failing restore, this
   * function must be called too, regardless of the result of
   * platform_pre_restore().
   */
  static void platform_restore_cleanup(int platform_mode)
  {
  	if (platform_mode && hibernation_ops)
  		hibernation_ops->restore_cleanup();
  }
  
  /**
   * platform_recover - Recover from a failure to suspend devices.
   * @platform_mode: Whether or not to use the platform driver.
   */
  static void platform_recover(int platform_mode)
  {
  	if (platform_mode && hibernation_ops && hibernation_ops->recover)
  		hibernation_ops->recover();
  }
  
  /**
   * swsusp_show_speed - Print time elapsed between two events during hibernation.
   * @start: Starting event.
   * @stop: Final event.
   * @nr_pages: Number of memory pages processed between @start and @stop.
   * @msg: Additional diagnostic message to print.
   */
  void swsusp_show_speed(ktime_t start, ktime_t stop,
  		      unsigned nr_pages, char *msg)
  {
  	ktime_t diff;
  	u64 elapsed_centisecs64;
  	unsigned int centisecs;
  	unsigned int k;
  	unsigned int kps;
  
  	diff = ktime_sub(stop, start);
  	elapsed_centisecs64 = ktime_divns(diff, 10*NSEC_PER_MSEC);
  	centisecs = elapsed_centisecs64;
  	if (centisecs == 0)
  		centisecs = 1;	/* avoid div-by-zero */
  	k = nr_pages * (PAGE_SIZE / 1024);
  	kps = (k * 100) / centisecs;
  	pr_info("%s %u kbytes in %u.%02u seconds (%u.%02u MB/s)\n",
  		msg, k, centisecs / 100, centisecs % 100, kps / 1000,
  		(kps % 1000) / 10);
  }
  
  __weak int arch_resume_nosmt(void)
  {
  	return 0;
  }
  
  /**
   * create_image - Create a hibernation image.
   * @platform_mode: Whether or not to use the platform driver.
   *
   * Execute device drivers' "late" and "noirq" freeze callbacks, create a
   * hibernation image and run the drivers' "noirq" and "early" thaw callbacks.
   *
   * Control reappears in this routine after the subsequent restore.
   */
  static int create_image(int platform_mode)
  {
  	int error;
  
  	error = dpm_suspend_end(PMSG_FREEZE);
  	if (error) {
  		pr_err("Some devices failed to power down, aborting hibernation\n");
  		return error;
  	}
  
  	error = platform_pre_snapshot(platform_mode);
  	if (error || hibernation_test(TEST_PLATFORM))
  		goto Platform_finish;
  
  	error = suspend_disable_secondary_cpus();
  	if (error || hibernation_test(TEST_CPUS))
  		goto Enable_cpus;
  
  	local_irq_disable();
  
  	system_state = SYSTEM_SUSPEND;
  
  	error = syscore_suspend();
  	if (error) {
  		pr_err("Some system devices failed to power down, aborting hibernation\n");
  		goto Enable_irqs;
  	}
  
  	if (hibernation_test(TEST_CORE) || pm_wakeup_pending())
  		goto Power_up;
  
  	in_suspend = 1;
  	save_processor_state();
  	trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, true);
  	error = swsusp_arch_suspend();
  	/* Restore control flow magically appears here */
  	restore_processor_state();
  	trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, false);
  	if (error)
  		pr_err("Error %d creating hibernation image\n", error);
  
  	if (!in_suspend) {
  		events_check_enabled = false;
  		clear_free_pages();
  	}
  
  	platform_leave(platform_mode);
  
   Power_up:
  	syscore_resume();
  
   Enable_irqs:
  	system_state = SYSTEM_RUNNING;
  	local_irq_enable();
  
   Enable_cpus:
  	suspend_enable_secondary_cpus();
  
  	/* Allow architectures to do nosmt-specific post-resume dances */
  	if (!in_suspend)
  		error = arch_resume_nosmt();
  
   Platform_finish:
  	platform_finish(platform_mode);
  
  	dpm_resume_start(in_suspend ?
  		(error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE);
  
  	return error;
  }
  
  /**
   * hibernation_snapshot - Quiesce devices and create a hibernation image.
   * @platform_mode: If set, use platform driver to prepare for the transition.
   *
   * This routine must be called with system_transition_mutex held.
   */
  int hibernation_snapshot(int platform_mode)
  {
  	pm_message_t msg;
  	int error;
  
  	pm_suspend_clear_flags();
  	error = platform_begin(platform_mode);
  	if (error)
  		goto Close;
  
  	/* Preallocate image memory before shutting down devices. */
  	error = hibernate_preallocate_memory();
  	if (error)
  		goto Close;
  
  	error = freeze_kernel_threads();
  	if (error)
  		goto Cleanup;
  
  	if (hibernation_test(TEST_FREEZER)) {
  
  		/*
  		 * Indicate to the caller that we are returning due to a
  		 * successful freezer test.
  		 */
  		freezer_test_done = true;
  		goto Thaw;
  	}
  
  	error = dpm_prepare(PMSG_FREEZE);
  	if (error) {
  		dpm_complete(PMSG_RECOVER);
  		goto Thaw;
  	}
  
  	suspend_console();
  	pm_restrict_gfp_mask();
  
  	error = dpm_suspend(PMSG_FREEZE);
  
  	if (error || hibernation_test(TEST_DEVICES))
  		platform_recover(platform_mode);
  	else
  		error = create_image(platform_mode);
  
  	/*
  	 * In the case that we call create_image() above, the control
  	 * returns here (1) after the image has been created or the
  	 * image creation has failed and (2) after a successful restore.
  	 */
  
  	/* We may need to release the preallocated image pages here. */
  	if (error || !in_suspend)
  		swsusp_free();
  
  	msg = in_suspend ? (error ? PMSG_RECOVER : PMSG_THAW) : PMSG_RESTORE;
  	dpm_resume(msg);
  
  	if (error || !in_suspend)
  		pm_restore_gfp_mask();
  
  	resume_console();
  	dpm_complete(msg);
  
   Close:
  	platform_end(platform_mode);
  	return error;
  
   Thaw:
  	thaw_kernel_threads();
   Cleanup:
  	swsusp_free();
  	goto Close;
  }
  
  int __weak hibernate_resume_nonboot_cpu_disable(void)
  {
  	return suspend_disable_secondary_cpus();
  }
  
  /**
   * resume_target_kernel - Restore system state from a hibernation image.
   * @platform_mode: Whether or not to use the platform driver.
   *
   * Execute device drivers' "noirq" and "late" freeze callbacks, restore the
   * contents of highmem that have not been restored yet from the image and run
   * the low-level code that will restore the remaining contents of memory and
   * switch to the just restored target kernel.
   */
  static int resume_target_kernel(bool platform_mode)
  {
  	int error;
  
  	error = dpm_suspend_end(PMSG_QUIESCE);
  	if (error) {
  		pr_err("Some devices failed to power down, aborting resume\n");
  		return error;
  	}
  
  	error = platform_pre_restore(platform_mode);
  	if (error)
  		goto Cleanup;
  
  	error = hibernate_resume_nonboot_cpu_disable();
  	if (error)
  		goto Enable_cpus;
  
  	local_irq_disable();
  	system_state = SYSTEM_SUSPEND;
  
  	error = syscore_suspend();
  	if (error)
  		goto Enable_irqs;
  
  	save_processor_state();
  	error = restore_highmem();
  	if (!error) {
  		error = swsusp_arch_resume();
  		/*
  		 * The code below is only ever reached in case of a failure.
  		 * Otherwise, execution continues at the place where
  		 * swsusp_arch_suspend() was called.
  		 */
  		BUG_ON(!error);
  		/*
  		 * This call to restore_highmem() reverts the changes made by
  		 * the previous one.
  		 */
  		restore_highmem();
  	}
  	/*
  	 * The only reason why swsusp_arch_resume() can fail is memory being
  	 * very tight, so we have to free it as soon as we can to avoid
  	 * subsequent failures.
  	 */
  	swsusp_free();
  	restore_processor_state();
  	touch_softlockup_watchdog();
  
  	syscore_resume();
  
   Enable_irqs:
  	system_state = SYSTEM_RUNNING;
  	local_irq_enable();
  
   Enable_cpus:
  	suspend_enable_secondary_cpus();
  
   Cleanup:
  	platform_restore_cleanup(platform_mode);
  
  	dpm_resume_start(PMSG_RECOVER);
  
  	return error;
  }
  
  /**
   * hibernation_restore - Quiesce devices and restore from a hibernation image.
   * @platform_mode: If set, use platform driver to prepare for the transition.
   *
   * This routine must be called with system_transition_mutex held.  If it is
   * successful, control reappears in the restored target kernel in
   * hibernation_snapshot().
   */
  int hibernation_restore(int platform_mode)
  {
  	int error;
  
  	pm_prepare_console();
  	suspend_console();
  	pm_restrict_gfp_mask();
  	error = dpm_suspend_start(PMSG_QUIESCE);
  	if (!error) {
  		error = resume_target_kernel(platform_mode);
  		/*
  		 * The above should either succeed and jump to the new kernel,
  		 * or return with an error. Otherwise things are just
  		 * undefined, so let's be paranoid.
  		 */
  		BUG_ON(!error);
  	}
  	dpm_resume_end(PMSG_RECOVER);
  	pm_restore_gfp_mask();
  	resume_console();
  	pm_restore_console();
  	return error;
  }
  
  /**
   * hibernation_platform_enter - Power off the system using the platform driver.
   */
  int hibernation_platform_enter(void)
  {
  	int error;
  
  	if (!hibernation_ops)
  		return -ENOSYS;
  
  	/*
  	 * We have cancelled the power transition by running
  	 * hibernation_ops->finish() before saving the image, so we should let
  	 * the firmware know that we're going to enter the sleep state after all
  	 */
  	error = hibernation_ops->begin(PMSG_HIBERNATE);
  	if (error)
  		goto Close;
  
  	entering_platform_hibernation = true;
  	suspend_console();
  	error = dpm_suspend_start(PMSG_HIBERNATE);
  	if (error) {
  		if (hibernation_ops->recover)
  			hibernation_ops->recover();
  		goto Resume_devices;
  	}
  
  	error = dpm_suspend_end(PMSG_HIBERNATE);
  	if (error)
  		goto Resume_devices;
  
  	error = hibernation_ops->prepare();
  	if (error)
  		goto Platform_finish;
  
  	error = suspend_disable_secondary_cpus();
  	if (error)
  		goto Enable_cpus;
  
  	local_irq_disable();
  	system_state = SYSTEM_SUSPEND;
  	syscore_suspend();
  	if (pm_wakeup_pending()) {
  		error = -EAGAIN;
  		goto Power_up;
  	}
  
  	hibernation_ops->enter();
  	/* We should never get here */
  	while (1);
  
   Power_up:
  	syscore_resume();
  	system_state = SYSTEM_RUNNING;
  	local_irq_enable();
  
   Enable_cpus:
  	suspend_enable_secondary_cpus();
  
   Platform_finish:
  	hibernation_ops->finish();
  
  	dpm_resume_start(PMSG_RESTORE);
  
   Resume_devices:
  	entering_platform_hibernation = false;
  	dpm_resume_end(PMSG_RESTORE);
  	resume_console();
  
   Close:
  	hibernation_ops->end();
  
  	return error;
  }
  
  /**
   * power_down - Shut the machine down for hibernation.
   *
   * Use the platform driver, if configured, to put the system into the sleep
   * state corresponding to hibernation, or try to power it off or reboot,
   * depending on the value of hibernation_mode.
   */
  static void power_down(void)
  {
  #ifdef CONFIG_SUSPEND
  	int error;
  
  	if (hibernation_mode == HIBERNATION_SUSPEND) {
  		error = suspend_devices_and_enter(PM_SUSPEND_MEM);
  		if (error) {
  			hibernation_mode = hibernation_ops ?
  						HIBERNATION_PLATFORM :
  						HIBERNATION_SHUTDOWN;
  		} else {
  			/* Restore swap signature. */
  			error = swsusp_unmark();
  			if (error)
  				pr_err("Swap will be unusable! Try swapon -a.\n");
  
  			return;
  		}
  	}
  #endif
  
  	switch (hibernation_mode) {
  	case HIBERNATION_REBOOT:
  		kernel_restart(NULL);
  		break;
  	case HIBERNATION_PLATFORM:
  		hibernation_platform_enter();
  		/* Fall through */
  	case HIBERNATION_SHUTDOWN:
  		if (pm_power_off)
  			kernel_power_off();
  		break;
  	}
  	kernel_halt();
  	/*
  	 * Valid image is on the disk, if we continue we risk serious data
  	 * corruption after resume.
  	 */
  	pr_crit("Power down manually\n");
  	while (1)
  		cpu_relax();
  }
  
  static int load_image_and_restore(void)
  {
  	int error;
  	unsigned int flags;
  
  	pm_pr_dbg("Loading hibernation image.\n");
  
  	lock_device_hotplug();
  	error = create_basic_memory_bitmaps();
  	if (error)
  		goto Unlock;
  
  	error = swsusp_read(&flags);
  	swsusp_close(FMODE_READ);
  	if (!error)
  		hibernation_restore(flags & SF_PLATFORM_MODE);
  
  	pr_err("Failed to load hibernation image, recovering.\n");
  	swsusp_free();
  	free_basic_memory_bitmaps();
   Unlock:
  	unlock_device_hotplug();
  
  	return error;
  }
  
  /**
   * hibernate - Carry out system hibernation, including saving the image.
   */
  int hibernate(void)
  {
  	int error, nr_calls = 0;
  	bool snapshot_test = false;
  
  	if (!hibernation_available()) {
  		pm_pr_dbg("Hibernation not available.\n");
  		return -EPERM;
  	}
  
  	lock_system_sleep();
  	/* The snapshot device should not be opened while we're running */
  	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
  		error = -EBUSY;
  		goto Unlock;
  	}
  
  	pr_info("hibernation entry\n");
  	pm_prepare_console();
  	error = __pm_notifier_call_chain(PM_HIBERNATION_PREPARE, -1, &nr_calls);
  	if (error) {
  		nr_calls--;
  		goto Exit;
  	}
  
  	ksys_sync_helper();
  
  	error = freeze_processes();
  	if (error)
  		goto Exit;
  
  	lock_device_hotplug();
  	/* Allocate memory management structures */
  	error = create_basic_memory_bitmaps();
  	if (error)
  		goto Thaw;
  
  	error = hibernation_snapshot(hibernation_mode == HIBERNATION_PLATFORM);
  	if (error || freezer_test_done)
  		goto Free_bitmaps;
  
  	if (in_suspend) {
  		unsigned int flags = 0;
  
  		if (hibernation_mode == HIBERNATION_PLATFORM)
  			flags |= SF_PLATFORM_MODE;
  		if (nocompress)
  			flags |= SF_NOCOMPRESS_MODE;
  		else
  		        flags |= SF_CRC32_MODE;
  
  		pm_pr_dbg("Writing image.\n");
  		error = swsusp_write(flags);
  		swsusp_free();
  		if (!error) {
  			if (hibernation_mode == HIBERNATION_TEST_RESUME)
  				snapshot_test = true;
  			else
  				power_down();
  		}
  		in_suspend = 0;
  		pm_restore_gfp_mask();
  	} else {
  		pm_pr_dbg("Image restored successfully.\n");
  	}
  
   Free_bitmaps:
  	free_basic_memory_bitmaps();
   Thaw:
  	unlock_device_hotplug();
  	if (snapshot_test) {
  		pm_pr_dbg("Checking hibernation image\n");
  		error = swsusp_check();
  		if (!error)
  			error = load_image_and_restore();
  	}
  	thaw_processes();
  
  	/* Don't bother checking whether freezer_test_done is true */
  	freezer_test_done = false;
   Exit:
  	__pm_notifier_call_chain(PM_POST_HIBERNATION, nr_calls, NULL);
  	pm_restore_console();
  	atomic_inc(&snapshot_device_available);
   Unlock:
  	unlock_system_sleep();
  	pr_info("hibernation exit\n");
  
  	return error;
  }
  
  
  /**
   * software_resume - Resume from a saved hibernation image.
   *
   * This routine is called as a late initcall, when all devices have been
   * discovered and initialized already.
   *
   * The image reading code is called to see if there is a hibernation image
   * available for reading.  If that is the case, devices are quiesced and the
   * contents of memory is restored from the saved image.
   *
   * If this is successful, control reappears in the restored target kernel in
   * hibernation_snapshot() which returns to hibernate().  Otherwise, the routine
   * attempts to recover gracefully and make the kernel return to the normal mode
   * of operation.
   */
  static int software_resume(void)
  {
  	int error, nr_calls = 0;
  
  	/*
  	 * If the user said "noresume".. bail out early.
  	 */
  	if (noresume || !hibernation_available())
  		return 0;
  
  	/*
  	 * name_to_dev_t() below takes a sysfs buffer mutex when sysfs
  	 * is configured into the kernel. Since the regular hibernate
  	 * trigger path is via sysfs which takes a buffer mutex before
  	 * calling hibernate functions (which take system_transition_mutex)
  	 * this can cause lockdep to complain about a possible ABBA deadlock
  	 * which cannot happen since we're in the boot code here and
  	 * sysfs can't be invoked yet. Therefore, we use a subclass
  	 * here to avoid lockdep complaining.
  	 */
  	mutex_lock_nested(&system_transition_mutex, SINGLE_DEPTH_NESTING);
  
  	if (swsusp_resume_device)
  		goto Check_image;
  
  	if (!strlen(resume_file)) {
  		error = -ENOENT;
  		goto Unlock;
  	}
  
  	pm_pr_dbg("Checking hibernation image partition %s\n", resume_file);
  
  	if (resume_delay) {
  		pr_info("Waiting %dsec before reading resume device ...\n",
  			resume_delay);
  		ssleep(resume_delay);
  	}
  
  	/* Check if the device is there */
  	swsusp_resume_device = name_to_dev_t(resume_file);
  
  	/*
  	 * name_to_dev_t is ineffective to verify parition if resume_file is in
  	 * integer format. (e.g. major:minor)
  	 */
  	if (isdigit(resume_file[0]) && resume_wait) {
  		int partno;
  		while (!get_gendisk(swsusp_resume_device, &partno))
  			msleep(10);
  	}
  
  	if (!swsusp_resume_device) {
  		/*
  		 * Some device discovery might still be in progress; we need
  		 * to wait for this to finish.
  		 */
  		wait_for_device_probe();
  
  		if (resume_wait) {
  			while ((swsusp_resume_device = name_to_dev_t(resume_file)) == 0)
  				msleep(10);
  			async_synchronize_full();
  		}
  
  		swsusp_resume_device = name_to_dev_t(resume_file);
  		if (!swsusp_resume_device) {
  			error = -ENODEV;
  			goto Unlock;
  		}
  	}
  
   Check_image:
  	pm_pr_dbg("Hibernation image partition %d:%d present\n",
  		MAJOR(swsusp_resume_device), MINOR(swsusp_resume_device));
  
  	pm_pr_dbg("Looking for hibernation image.\n");
  	error = swsusp_check();
  	if (error)
  		goto Unlock;
  
  	/* The snapshot device should not be opened while we're running */
  	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
  		error = -EBUSY;
  		swsusp_close(FMODE_READ);
  		goto Unlock;
  	}
  
  	pr_info("resume from hibernation\n");
  	pm_prepare_console();
  	error = __pm_notifier_call_chain(PM_RESTORE_PREPARE, -1, &nr_calls);
  	if (error) {
  		nr_calls--;
  		goto Close_Finish;
  	}
  
  	pm_pr_dbg("Preparing processes for restore.\n");
  	error = freeze_processes();
  	if (error)
  		goto Close_Finish;
  	error = load_image_and_restore();
  	thaw_processes();
   Finish:
  	__pm_notifier_call_chain(PM_POST_RESTORE, nr_calls, NULL);
  	pm_restore_console();
  	pr_info("resume from hibernation failed (%d)\n", error);
  	atomic_inc(&snapshot_device_available);
  	/* For success case, the suspend path will release the lock */
   Unlock:
  	mutex_unlock(&system_transition_mutex);
  	pm_pr_dbg("Hibernation image not present or could not be loaded.\n");
  	return error;
   Close_Finish:
  	swsusp_close(FMODE_READ);
  	goto Finish;
  }
  
  late_initcall_sync(software_resume);
  
  
  static const char * const hibernation_modes[] = {
  	[HIBERNATION_PLATFORM]	= "platform",
  	[HIBERNATION_SHUTDOWN]	= "shutdown",
  	[HIBERNATION_REBOOT]	= "reboot",
  #ifdef CONFIG_SUSPEND
  	[HIBERNATION_SUSPEND]	= "suspend",
  #endif
  	[HIBERNATION_TEST_RESUME]	= "test_resume",
  };
  
  /*
   * /sys/power/disk - Control hibernation mode.
   *
   * Hibernation can be handled in several ways.  There are a few different ways
   * to put the system into the sleep state: using the platform driver (e.g. ACPI
   * or other hibernation_ops), powering it off or rebooting it (for testing
   * mostly).
   *
   * The sysfs file /sys/power/disk provides an interface for selecting the
   * hibernation mode to use.  Reading from this file causes the available modes
   * to be printed.  There are 3 modes that can be supported:
   *
   *	'platform'
   *	'shutdown'
   *	'reboot'
   *
   * If a platform hibernation driver is in use, 'platform' will be supported
   * and will be used by default.  Otherwise, 'shutdown' will be used by default.
   * The selected option (i.e. the one corresponding to the current value of
   * hibernation_mode) is enclosed by a square bracket.
   *
   * To select a given hibernation mode it is necessary to write the mode's
   * string representation (as returned by reading from /sys/power/disk) back
   * into /sys/power/disk.
   */
  
  static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
  			 char *buf)
  {
  	int i;
  	char *start = buf;
  
  	if (!hibernation_available())
  		return sprintf(buf, "[disabled]\n");
  
  	for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
  		if (!hibernation_modes[i])
  			continue;
  		switch (i) {
  		case HIBERNATION_SHUTDOWN:
  		case HIBERNATION_REBOOT:
  #ifdef CONFIG_SUSPEND
  		case HIBERNATION_SUSPEND:
  #endif
  		case HIBERNATION_TEST_RESUME:
  			break;
  		case HIBERNATION_PLATFORM:
  			if (hibernation_ops)
  				break;
  			/* not a valid mode, continue with loop */
  			continue;
  		}
  		if (i == hibernation_mode)
  			buf += sprintf(buf, "[%s] ", hibernation_modes[i]);
  		else
  			buf += sprintf(buf, "%s ", hibernation_modes[i]);
  	}
  	buf += sprintf(buf, "\n");
  	return buf-start;
  }
  
  static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
  			  const char *buf, size_t n)
  {
  	int error = 0;
  	int i;
  	int len;
  	char *p;
  	int mode = HIBERNATION_INVALID;
  
  	if (!hibernation_available())
  		return -EPERM;
  
  	p = memchr(buf, '\n', n);
  	len = p ? p - buf : n;
  
  	lock_system_sleep();
  	for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
  		if (len == strlen(hibernation_modes[i])
  		    && !strncmp(buf, hibernation_modes[i], len)) {
  			mode = i;
  			break;
  		}
  	}
  	if (mode != HIBERNATION_INVALID) {
  		switch (mode) {
  		case HIBERNATION_SHUTDOWN:
  		case HIBERNATION_REBOOT:
  #ifdef CONFIG_SUSPEND
  		case HIBERNATION_SUSPEND:
  #endif
  		case HIBERNATION_TEST_RESUME:
  			hibernation_mode = mode;
  			break;
  		case HIBERNATION_PLATFORM:
  			if (hibernation_ops)
  				hibernation_mode = mode;
  			else
  				error = -EINVAL;
  		}
  	} else
  		error = -EINVAL;
  
  	if (!error)
  		pm_pr_dbg("Hibernation mode set to '%s'\n",
  			       hibernation_modes[mode]);
  	unlock_system_sleep();
  	return error ? error : n;
  }
  
  power_attr(disk);
  
  static ssize_t resume_show(struct kobject *kobj, struct kobj_attribute *attr,
  			   char *buf)
  {
  	return sprintf(buf,"%d:%d\n", MAJOR(swsusp_resume_device),
  		       MINOR(swsusp_resume_device));
  }
  
  static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
  			    const char *buf, size_t n)
  {
  	dev_t res;
  	int len = n;
  	char *name;
  
  	if (len && buf[len-1] == '\n')
  		len--;
  	name = kstrndup(buf, len, GFP_KERNEL);
  	if (!name)
  		return -ENOMEM;
  
  	res = name_to_dev_t(name);
  	kfree(name);
  	if (!res)
  		return -EINVAL;
  
  	lock_system_sleep();
  	swsusp_resume_device = res;
  	unlock_system_sleep();
  	pm_pr_dbg("Configured resume from disk to %u\n", swsusp_resume_device);
  	noresume = 0;
  	software_resume();
  	return n;
  }
  
  power_attr(resume);
  
  static ssize_t resume_offset_show(struct kobject *kobj,
  				  struct kobj_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%llu\n", (unsigned long long)swsusp_resume_block);
  }
  
  static ssize_t resume_offset_store(struct kobject *kobj,
  				   struct kobj_attribute *attr, const char *buf,
  				   size_t n)
  {
  	unsigned long long offset;
  	int rc;
  
  	rc = kstrtoull(buf, 0, &offset);
  	if (rc)
  		return rc;
  	swsusp_resume_block = offset;
  
  	return n;
  }
  
  power_attr(resume_offset);
  
  static ssize_t image_size_show(struct kobject *kobj, struct kobj_attribute *attr,
  			       char *buf)
  {
  	return sprintf(buf, "%lu\n", image_size);
  }
  
  static ssize_t image_size_store(struct kobject *kobj, struct kobj_attribute *attr,
  				const char *buf, size_t n)
  {
  	unsigned long size;
  
  	if (sscanf(buf, "%lu", &size) == 1) {
  		image_size = size;
  		return n;
  	}
  
  	return -EINVAL;
  }
  
  power_attr(image_size);
  
  static ssize_t reserved_size_show(struct kobject *kobj,
  				  struct kobj_attribute *attr, char *buf)
  {
  	return sprintf(buf, "%lu\n", reserved_size);
  }
  
  static ssize_t reserved_size_store(struct kobject *kobj,
  				   struct kobj_attribute *attr,
  				   const char *buf, size_t n)
  {
  	unsigned long size;
  
  	if (sscanf(buf, "%lu", &size) == 1) {
  		reserved_size = size;
  		return n;
  	}
  
  	return -EINVAL;
  }
  
  power_attr(reserved_size);
  
  static struct attribute * g[] = {
  	&disk_attr.attr,
  	&resume_offset_attr.attr,
  	&resume_attr.attr,
  	&image_size_attr.attr,
  	&reserved_size_attr.attr,
  	NULL,
  };
  
  
  static const struct attribute_group attr_group = {
  	.attrs = g,
  };
  
  
  static int __init pm_disk_init(void)
  {
  	return sysfs_create_group(power_kobj, &attr_group);
  }
  
  core_initcall(pm_disk_init);
  
  
  static int __init resume_setup(char *str)
  {
  	if (noresume)
  		return 1;
  
  	strncpy( resume_file, str, 255 );
  	return 1;
  }
  
  static int __init resume_offset_setup(char *str)
  {
  	unsigned long long offset;
  
  	if (noresume)
  		return 1;
  
  	if (sscanf(str, "%llu", &offset) == 1)
  		swsusp_resume_block = offset;
  
  	return 1;
  }
  
  static int __init hibernate_setup(char *str)
  {
  	if (!strncmp(str, "noresume", 8)) {
  		noresume = 1;
  	} else if (!strncmp(str, "nocompress", 10)) {
  		nocompress = 1;
  	} else if (!strncmp(str, "no", 2)) {
  		noresume = 1;
  		nohibernate = 1;
  	} else if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)
  		   && !strncmp(str, "protect_image", 13)) {
  		enable_restore_image_protection();
  	}
  	return 1;
  }
  
  static int __init noresume_setup(char *str)
  {
  	noresume = 1;
  	return 1;
  }
  
  static int __init resumewait_setup(char *str)
  {
  	resume_wait = 1;
  	return 1;
  }
  
  static int __init resumedelay_setup(char *str)
  {
  	int rc = kstrtouint(str, 0, &resume_delay);
  
  	if (rc)
  		return rc;
  	return 1;
  }
  
  static int __init nohibernate_setup(char *str)
  {
  	noresume = 1;
  	nohibernate = 1;
  	return 1;
  }
  
  __setup("noresume", noresume_setup);
  __setup("resume_offset=", resume_offset_setup);
  __setup("resume=", resume_setup);
  __setup("hibernate=", hibernate_setup);
  __setup("resumewait", resumewait_setup);
  __setup("resumedelay=", resumedelay_setup);
  __setup("nohibernate", nohibernate_setup);
  