Merge branches 'pm-cpuidle', 'pm-core' and 'pm-sleep'

Merge cpuidle updates, PM core updates and one hiberation-related
update for 5.17-rc1:

- Make cpuidle use default_groups in kobj_type (Greg Kroah-Hartman).

- Fix two comments in cpuidle code (Jason Wang, Yang Li).

- Simplify locking in pm_runtime_put_suppliers() (Rafael Wysocki).

- Add safety net to supplier device release in the runtime PM core
code (Rafael Wysocki).

- Capture device status before disabling runtime PM for it (Rafael
Wysocki).

- Add new macros for declaring PM operations to allow drivers to
avoid guarding them with CONFIG_PM #ifdefs or __maybe_unused and
update some drivers to use these macros (Paul Cercueil).

- Allow ACPI hardware signature to be honoured during restore from
hibernation (David Woodhouse).

* pm-cpuidle:
cpuidle: use default_groups in kobj_type
cpuidle: Fix cpuidle_remove_state_sysfs() kerneldoc comment
cpuidle: menu: Fix typo in a comment

* pm-core:
PM: runtime: Simplify locking in pm_runtime_put_suppliers()
mmc: mxc: Use the new PM macros
mmc: jz4740: Use the new PM macros
PM: runtime: Add safety net to supplier device release
PM: runtime: Capture device status before disabling runtime PM
PM: core: Add new *_PM_OPS macros, deprecate old ones
PM: core: Redefine pm_ptr() macro
r8169: Avoid misuse of pm_ptr() macro

* pm-sleep:
PM: hibernate: Allow ACPI hardware signature to be honoured

Documentation/admin-guide/kernel-parameters.txt

···
 			For broken nForce2 BIOS resulting in XT-PIC timer.
 
 	acpi_sleep=	[HW,ACPI] Sleep options
-			Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
-				  old_ordering, nonvs, sci_force_enable, nobl }
+			Format: { s3_bios, s3_mode, s3_beep, s4_hwsig,
+				  s4_nohwsig, old_ordering, nonvs,
+				  sci_force_enable, nobl }
 			See Documentation/power/video.rst for information on
 			s3_bios and s3_mode.
 			s3_beep is for debugging; it makes the PC's speaker beep
 			as soon as the kernel's real-mode entry point is called.
+			s4_hwsig causes the kernel to check the ACPI hardware
+			signature during resume from hibernation, and gracefully
+			refuse to resume if it has changed. This complies with
+			the ACPI specification but not with reality, since
+			Windows does not do this and many laptops do change it
+			on docking. So the default behaviour is to allow resume
+			and simply warn when the signature changes, unless the
+			s4_hwsig option is enabled.
 			s4_nohwsig prevents ACPI hardware signature from being
-			used during resume from hibernation.
+			used (or even warned about) during resume.
 			old_ordering causes the ACPI 1.0 ordering of the _PTS
 			control method, with respect to putting devices into
 			low power states, to be enforced (the ACPI 2.0 ordering

Documentation/power/runtime_pm.rst

···
       RPM_SUSPENDED, which means that each device is initially regarded by the
       PM core as 'suspended', regardless of its real hardware status
 
+  `enum rpm_status last_status;`
+    - the last runtime PM status of the device captured before disabling runtime
+      PM for it (invalid initially and when disable_depth is 0)
+
   `unsigned int runtime_auto;`
     - if set, indicates that the user space has allowed the device driver to
       power manage the device at run time via the /sys/devices/.../power/control
···
 
   `int pm_runtime_resume(struct device *dev);`
     - execute the subsystem-level resume callback for the device; returns 0 on
-      success, 1 if the device's runtime PM status was already 'active' or
-      error code on failure, where -EAGAIN means it may be safe to attempt to
-      resume the device again in future, but 'power.runtime_error' should be
-      checked additionally, and -EACCES means that 'power.disable_depth' is
+      success, 1 if the device's runtime PM status is already 'active' (also if
+      'power.disable_depth' is nonzero, but the status was 'active' when it was
+      changing from 0 to 1) or error code on failure, where -EAGAIN means it may
+      be safe to attempt to resume the device again in future, but
+      'power.runtime_error' should be checked additionally, and -EACCES means
+      that the callback could not be run, because 'power.disable_depth' was
       different from 0
 
   `int pm_runtime_resume_and_get(struct device *dev);`

arch/x86/kernel/acpi/sleep.c

···
 		if (strncmp(str, "s3_beep", 7) == 0)
 			acpi_realmode_flags |= 4;
 #ifdef CONFIG_HIBERNATION
+		if (strncmp(str, "s4_hwsig", 8) == 0)
+			acpi_check_s4_hw_signature(1);
 		if (strncmp(str, "s4_nohwsig", 10) == 0)
-			acpi_no_s4_hw_signature();
+			acpi_check_s4_hw_signature(0);
 #endif
 		if (strncmp(str, "nonvs", 5) == 0)
 			acpi_nvs_nosave();

drivers/acpi/sleep.c

···
 #ifdef CONFIG_HIBERNATION
 static unsigned long s4_hardware_signature;
 static struct acpi_table_facs *facs;
-static bool nosigcheck;
+static int sigcheck = -1; /* Default behaviour is just to warn */
 
-void __init acpi_no_s4_hw_signature(void)
+void __init acpi_check_s4_hw_signature(int check)
 {
-	nosigcheck = true;
+	sigcheck = check;
 }
 
 static int acpi_hibernation_begin(pm_message_t stage)
···
 	hibernation_set_ops(old_suspend_ordering ?
 			&acpi_hibernation_ops_old : &acpi_hibernation_ops);
 	sleep_states[ACPI_STATE_S4] = 1;
-	if (nosigcheck)
+	if (!sigcheck)
 		return;
 
 	acpi_get_table(ACPI_SIG_FACS, 1, (struct acpi_table_header **)&facs);
-	if (facs)
+	if (facs) {
+		/*
+		 * s4_hardware_signature is the local variable which is just
+		 * used to warn about mismatch after we're attempting to
+		 * resume (in violation of the ACPI specification.)
+		 */
 		s4_hardware_signature = facs->hardware_signature;
+
+		if (sigcheck > 0) {
+			/*
+			 * If we're actually obeying the ACPI specification
+			 * then the signature is written out as part of the
+			 * swsusp header, in order to allow the boot kernel
+			 * to gracefully decline to resume.
+			 */
+			swsusp_hardware_signature = facs->hardware_signature;
+		}
+	}
 }
 #else /* !CONFIG_HIBERNATION */
 static inline void acpi_sleep_hibernate_setup(void) {}

drivers/base/core.c

···
 	/* Ensure that all references to the link object have been dropped. */
 	device_link_synchronize_removal();
 
-	while (refcount_dec_not_one(&link->rpm_active))
-		pm_runtime_put(link->supplier);
+	pm_runtime_release_supplier(link, true);
 
 	put_device(link->consumer);
 	put_device(link->supplier);

drivers/base/power/runtime.c

···
 	return 0;
 }
 
+/**
+ * pm_runtime_release_supplier - Drop references to device link's supplier.
+ * @link: Target device link.
+ * @check_idle: Whether or not to check if the supplier device is idle.
+ *
+ * Drop all runtime PM references associated with @link to its supplier device
+ * and if @check_idle is set, check if that device is idle (and so it can be
+ * suspended).
+ */
+void pm_runtime_release_supplier(struct device_link *link, bool check_idle)
+{
+	struct device *supplier = link->supplier;
+
+	/*
+	 * The additional power.usage_count check is a safety net in case
+	 * the rpm_active refcount becomes saturated, in which case
+	 * refcount_dec_not_one() would return true forever, but it is not
+	 * strictly necessary.
+	 */
+	while (refcount_dec_not_one(&link->rpm_active) &&
+	       atomic_read(&supplier->power.usage_count) > 0)
+		pm_runtime_put_noidle(supplier);
+
+	if (check_idle)
+		pm_request_idle(supplier);
+}
+
 static void __rpm_put_suppliers(struct device *dev, bool try_to_suspend)
 {
 	struct device_link *link;
 
 	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
-				device_links_read_lock_held()) {
-
-		while (refcount_dec_not_one(&link->rpm_active))
-			pm_runtime_put_noidle(link->supplier);
-
-		if (try_to_suspend)
-			pm_request_idle(link->supplier);
-	}
+				device_links_read_lock_held())
+		pm_runtime_release_supplier(link, try_to_suspend);
 }
 
 static void rpm_put_suppliers(struct device *dev)
···
 	trace_rpm_resume_rcuidle(dev, rpmflags);
 
  repeat:
-	if (dev->power.runtime_error)
+	if (dev->power.runtime_error) {
 		retval = -EINVAL;
-	else if (dev->power.disable_depth == 1 && dev->power.is_suspended
-	    && dev->power.runtime_status == RPM_ACTIVE)
-		retval = 1;
-	else if (dev->power.disable_depth > 0)
-		retval = -EACCES;
+	} else if (dev->power.disable_depth > 0) {
+		if (dev->power.runtime_status == RPM_ACTIVE &&
+		    dev->power.last_status == RPM_ACTIVE)
+			retval = 1;
+		else
+			retval = -EACCES;
+	}
 	if (retval)
 		goto out;
 
···
 	/* Update time accounting before disabling PM-runtime. */
 	update_pm_runtime_accounting(dev);
 
-	if (!dev->power.disable_depth++)
+	if (!dev->power.disable_depth++) {
 		__pm_runtime_barrier(dev);
+		dev->power.last_status = dev->power.runtime_status;
+	}
 
  out:
 	spin_unlock_irq(&dev->power.lock);
···
 
 	spin_lock_irqsave(&dev->power.lock, flags);
 
-	if (dev->power.disable_depth > 0) {
-		dev->power.disable_depth--;
-
-		/* About to enable runtime pm, set accounting_timestamp to now */
-		if (!dev->power.disable_depth)
-			dev->power.accounting_timestamp = ktime_get_mono_fast_ns();
-	} else {
+	if (!dev->power.disable_depth) {
 		dev_warn(dev, "Unbalanced %s!\n", __func__);
+		goto out;
 	}
 
-	WARN(!dev->power.disable_depth &&
-	     dev->power.runtime_status == RPM_SUSPENDED &&
-	     !dev->power.ignore_children &&
-	     atomic_read(&dev->power.child_count) > 0,
-	     "Enabling runtime PM for inactive device (%s) with active children\n",
-	     dev_name(dev));
+	if (--dev->power.disable_depth > 0)
+		goto out;
 
+	dev->power.last_status = RPM_INVALID;
+	dev->power.accounting_timestamp = ktime_get_mono_fast_ns();
+
+	if (dev->power.runtime_status == RPM_SUSPENDED &&
+	    !dev->power.ignore_children &&
+	    atomic_read(&dev->power.child_count) > 0)
+		dev_warn(dev, "Enabling runtime PM for inactive device with active children\n");
+
+out:
 	spin_unlock_irqrestore(&dev->power.lock, flags);
 }
 EXPORT_SYMBOL_GPL(pm_runtime_enable);
···
 void pm_runtime_init(struct device *dev)
 {
 	dev->power.runtime_status = RPM_SUSPENDED;
+	dev->power.last_status = RPM_INVALID;
 	dev->power.idle_notification = false;
 
 	dev->power.disable_depth = 1;
···
 void pm_runtime_put_suppliers(struct device *dev)
 {
 	struct device_link *link;
-	unsigned long flags;
-	bool put;
 	int idx;
 
 	idx = device_links_read_lock();
···
 	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node,
 				device_links_read_lock_held())
 		if (link->supplier_preactivated) {
+			bool put;
+
 			link->supplier_preactivated = false;
-			spin_lock_irqsave(&dev->power.lock, flags);
+
+			spin_lock_irq(&dev->power.lock);
+
 			put = pm_runtime_status_suspended(dev) &&
 			      refcount_dec_not_one(&link->rpm_active);
-			spin_unlock_irqrestore(&dev->power.lock, flags);
+
+			spin_unlock_irq(&dev->power.lock);
+
 			if (put)
 				pm_runtime_put(link->supplier);
 		}
···
 		return;
 
 	pm_runtime_drop_link_count(link->consumer);
-
-	while (refcount_dec_not_one(&link->rpm_active))
-		pm_runtime_put(link->supplier);
+	pm_runtime_release_supplier(link, true);
 }
 
 static bool pm_runtime_need_not_resume(struct device *dev)

drivers/cpuidle/governors/menu.c

···
  * 1) Energy break even point
  * 2) Performance impact
  * 3) Latency tolerance (from pmqos infrastructure)
- * These these three factors are treated independently.
+ * These three factors are treated independently.
  *
  * Energy break even point
  * -----------------------

drivers/cpuidle/sysfs.c

···
 	&attr_default_status.attr,
 	NULL
 };
+ATTRIBUTE_GROUPS(cpuidle_state_default);
 
 struct cpuidle_state_kobj {
 	struct cpuidle_state *state;
···
 
 static struct kobj_type ktype_state_cpuidle = {
 	.sysfs_ops = &cpuidle_state_sysfs_ops,
-	.default_attrs = cpuidle_state_default_attrs,
+	.default_groups = cpuidle_state_default_groups,
 	.release = cpuidle_state_sysfs_release,
 };
 
···
 }
 
 /**
- * cpuidle_remove_driver_sysfs - removes the cpuidle states sysfs attributes
+ * cpuidle_remove_state_sysfs - removes the cpuidle states sysfs attributes
  * @device: the target device
  */
 static void cpuidle_remove_state_sysfs(struct cpuidle_device *device)
···
 	&attr_driver_name.attr,
 	NULL
 };
+ATTRIBUTE_GROUPS(cpuidle_driver_default);
 
 static struct kobj_type ktype_driver_cpuidle = {
 	.sysfs_ops = &cpuidle_driver_sysfs_ops,
-	.default_attrs = cpuidle_driver_default_attrs,
+	.default_groups = cpuidle_driver_default_groups,
 	.release = cpuidle_driver_sysfs_release,
 };
 

drivers/mmc/host/jz4740_mmc.c

···
 	return 0;
 }
 
-static int __maybe_unused jz4740_mmc_suspend(struct device *dev)
+static int jz4740_mmc_suspend(struct device *dev)
 {
 	return pinctrl_pm_select_sleep_state(dev);
 }
 
-static int __maybe_unused jz4740_mmc_resume(struct device *dev)
+static int jz4740_mmc_resume(struct device *dev)
 {
 	return pinctrl_select_default_state(dev);
 }
 
-static SIMPLE_DEV_PM_OPS(jz4740_mmc_pm_ops, jz4740_mmc_suspend,
+DEFINE_SIMPLE_DEV_PM_OPS(jz4740_mmc_pm_ops, jz4740_mmc_suspend,
 	jz4740_mmc_resume);
 
 static struct platform_driver jz4740_mmc_driver = {
···
 		.name = "jz4740-mmc",
 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 		.of_match_table = of_match_ptr(jz4740_mmc_of_match),
-		.pm = pm_ptr(&jz4740_mmc_pm_ops),
+		.pm = pm_sleep_ptr(&jz4740_mmc_pm_ops),
 	},
 };
 

drivers/mmc/host/mxcmmc.c

···
 	return 0;
 }
 
-#ifdef CONFIG_PM_SLEEP
 static int mxcmci_suspend(struct device *dev)
 {
 	struct mmc_host *mmc = dev_get_drvdata(dev);
···
 
 	return ret;
 }
-#endif
 
-static SIMPLE_DEV_PM_OPS(mxcmci_pm_ops, mxcmci_suspend, mxcmci_resume);
+DEFINE_SIMPLE_DEV_PM_OPS(mxcmci_pm_ops, mxcmci_suspend, mxcmci_resume);
 
 static struct platform_driver mxcmci_driver = {
 	.probe		= mxcmci_probe,
···
 	.driver		= {
 		.name		= DRIVER_NAME,
 		.probe_type	= PROBE_PREFER_ASYNCHRONOUS,
-		.pm	= &mxcmci_pm_ops,
+		.pm	= pm_sleep_ptr(&mxcmci_pm_ops),
 		.of_match_table	= mxcmci_of_match,
 	}
 };

drivers/net/ethernet/realtek/r8169_main.c

···
 	.probe		= rtl_init_one,
 	.remove		= rtl_remove_one,
 	.shutdown	= rtl_shutdown,
-	.driver.pm	= pm_ptr(&rtl8169_pm_ops),
+#ifdef CONFIG_PM
+	.driver.pm	= &rtl8169_pm_ops,
+#endif
 };
 
 module_pci_driver(rtl8169_pci_driver);

include/linux/acpi.h

···
 int acpi_resources_are_enforced(void);
 
 #ifdef CONFIG_HIBERNATION
-void __init acpi_no_s4_hw_signature(void);
+void __init acpi_check_s4_hw_signature(int check);
 #endif
 
 #ifdef CONFIG_PM_SLEEP

include/linux/pm.h

···
 	int (*runtime_idle)(struct device *dev);
 };
 
+#define SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
+	.suspend = pm_sleep_ptr(suspend_fn), \
+	.resume = pm_sleep_ptr(resume_fn), \
+	.freeze = pm_sleep_ptr(suspend_fn), \
+	.thaw = pm_sleep_ptr(resume_fn), \
+	.poweroff = pm_sleep_ptr(suspend_fn), \
+	.restore = pm_sleep_ptr(resume_fn),
+
+#define LATE_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
+	.suspend_late = pm_sleep_ptr(suspend_fn), \
+	.resume_early = pm_sleep_ptr(resume_fn), \
+	.freeze_late = pm_sleep_ptr(suspend_fn), \
+	.thaw_early = pm_sleep_ptr(resume_fn), \
+	.poweroff_late = pm_sleep_ptr(suspend_fn), \
+	.restore_early = pm_sleep_ptr(resume_fn),
+
+#define NOIRQ_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
+	.suspend_noirq = pm_sleep_ptr(suspend_fn), \
+	.resume_noirq = pm_sleep_ptr(resume_fn), \
+	.freeze_noirq = pm_sleep_ptr(suspend_fn), \
+	.thaw_noirq = pm_sleep_ptr(resume_fn), \
+	.poweroff_noirq = pm_sleep_ptr(suspend_fn), \
+	.restore_noirq = pm_sleep_ptr(resume_fn),
+
+#define RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) \
+	.runtime_suspend = suspend_fn, \
+	.runtime_resume = resume_fn, \
+	.runtime_idle = idle_fn,
+
 #ifdef CONFIG_PM_SLEEP
 #define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
-	.suspend = suspend_fn, \
-	.resume = resume_fn, \
-	.freeze = suspend_fn, \
-	.thaw = resume_fn, \
-	.poweroff = suspend_fn, \
-	.restore = resume_fn,
+	SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
 #else
 #define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
 #endif
 
 #ifdef CONFIG_PM_SLEEP
 #define SET_LATE_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
-	.suspend_late = suspend_fn, \
-	.resume_early = resume_fn, \
-	.freeze_late = suspend_fn, \
-	.thaw_early = resume_fn, \
-	.poweroff_late = suspend_fn, \
-	.restore_early = resume_fn,
+	LATE_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
 #else
 #define SET_LATE_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
 #endif
 
 #ifdef CONFIG_PM_SLEEP
 #define SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
-	.suspend_noirq = suspend_fn, \
-	.resume_noirq = resume_fn, \
-	.freeze_noirq = suspend_fn, \
-	.thaw_noirq = resume_fn, \
-	.poweroff_noirq = suspend_fn, \
-	.restore_noirq = resume_fn,
+	NOIRQ_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
 #else
 #define SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
 #endif
 
 #ifdef CONFIG_PM
 #define SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) \
-	.runtime_suspend = suspend_fn, \
-	.runtime_resume = resume_fn, \
-	.runtime_idle = idle_fn,
+	RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn)
 #else
 #define SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn)
 #endif
···
  * Use this if you want to use the same suspend and resume callbacks for suspend
  * to RAM and hibernation.
  */
-#define SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
-const struct dev_pm_ops __maybe_unused name = { \
-	SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
+#define DEFINE_SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
+static const struct dev_pm_ops name = { \
+	SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
 }
 
 /*
···
  * .resume_early(), to the same routines as .runtime_suspend() and
  * .runtime_resume(), respectively (and analogously for hibernation).
  */
+#define DEFINE_UNIVERSAL_DEV_PM_OPS(name, suspend_fn, resume_fn, idle_fn) \
+static const struct dev_pm_ops name = { \
+	SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
+	RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) \
+}
+
+/* Deprecated. Use DEFINE_SIMPLE_DEV_PM_OPS() instead. */
+#define SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
+const struct dev_pm_ops __maybe_unused name = { \
+	SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
+}
+
+/* Deprecated. Use DEFINE_UNIVERSAL_DEV_PM_OPS() instead. */
 #define UNIVERSAL_DEV_PM_OPS(name, suspend_fn, resume_fn, idle_fn) \
 const struct dev_pm_ops __maybe_unused name = { \
 	SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
 	SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) \
 }
 
-#ifdef CONFIG_PM
-#define pm_ptr(_ptr) (_ptr)
-#else
-#define pm_ptr(_ptr) NULL
-#endif
+#define pm_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM), (_ptr))
+#define pm_sleep_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM_SLEEP), (_ptr))
 
 /*
  * PM_EVENT_ messages
···
  */
 
 enum rpm_status {
+	RPM_INVALID = -1,
 	RPM_ACTIVE = 0,
 	RPM_RESUMING,
 	RPM_SUSPENDED,
···
 	unsigned int		links_count;
 	enum rpm_request	request;
 	enum rpm_status		runtime_status;
+	enum rpm_status		last_status;
 	int			runtime_error;
 	int			autosuspend_delay;
 	u64			last_busy;

include/linux/pm_runtime.h

···
 extern void pm_runtime_put_suppliers(struct device *dev);
 extern void pm_runtime_new_link(struct device *dev);
 extern void pm_runtime_drop_link(struct device_link *link);
+extern void pm_runtime_release_supplier(struct device_link *link, bool check_idle);
 
 extern int devm_pm_runtime_enable(struct device *dev);
 
···
 static inline void pm_runtime_put_suppliers(struct device *dev) {}
 static inline void pm_runtime_new_link(struct device *dev) {}
 static inline void pm_runtime_drop_link(struct device_link *link) {}
+static inline void pm_runtime_release_supplier(struct device_link *link,
+					       bool check_idle) {}
 
 #endif /* !CONFIG_PM */
 

include/linux/suspend.h

···
 extern asmlinkage int swsusp_arch_suspend(void);
 extern asmlinkage int swsusp_arch_resume(void);
 
+extern u32 swsusp_hardware_signature;
 extern void hibernation_set_ops(const struct platform_hibernation_ops *ops);
 extern int hibernate(void);
 extern bool system_entering_hibernation(void);

kernel/power/power.h

···
 #define SF_PLATFORM_MODE	1
 #define SF_NOCOMPRESS_MODE	2
 #define SF_CRC32_MODE	        4
+#define SF_HW_SIG		8
 
 /* kernel/power/hibernate.c */
 extern int swsusp_check(void);

kernel/power/swap.c

···
 
 #define HIBERNATE_SIG	"S1SUSPEND"
 
+u32 swsusp_hardware_signature;
+
 /*
  * When reading an {un,}compressed image, we may restore pages in place,
  * in which case some architectures need these pages cleaning before they
···
 
 struct swsusp_header {
 	char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int) -
-	              sizeof(u32)];
+	              sizeof(u32) - sizeof(u32)];
+	u32	hw_sig;
 	u32	crc32;
 	sector_t image;
 	unsigned int flags;	/* Flags to pass to the "boot" kernel */
···
 /*
  * Saving part
  */
-
 static int mark_swapfiles(struct swap_map_handle *handle, unsigned int flags)
 {
 	int error;
···
 		memcpy(swsusp_header->orig_sig,swsusp_header->sig, 10);
 		memcpy(swsusp_header->sig, HIBERNATE_SIG, 10);
 		swsusp_header->image = handle->first_sector;
+		if (swsusp_hardware_signature) {
+			swsusp_header->hw_sig = swsusp_hardware_signature;
+			flags |= SF_HW_SIG;
+		}
 		swsusp_header->flags = flags;
 		if (flags & SF_CRC32_MODE)
 			swsusp_header->crc32 = handle->crc32;
···
 						swsusp_resume_block,
 						swsusp_header, NULL);
 		} else {
+			error = -EINVAL;
+		}
+		if (!error && swsusp_header->flags & SF_HW_SIG &&
+		    swsusp_header->hw_sig != swsusp_hardware_signature) {
+			pr_info("Suspend image hardware signature mismatch (%08x now %08x); aborting resume.\n",
+				swsusp_header->hw_sig, swsusp_hardware_signature);
 			error = -EINVAL;
 		}