Merge branches 'pm-sleep' and 'powercap'

* pm-sleep:
  PM / sleep: Print active wakeup sources when blocking on wakeup_count reads
  x86/suspend: fix false positive KASAN warning on suspend/resume
  PM / sleep / ACPI: Use the ACPI_FADT_LOW_POWER_S0 flag
  PM / sleep: System sleep state selection interface rework
  PM / hibernate: Verify the consistent of e820 memory map by md5 digest

* powercap:
  powercap / RAPL: Add Knights Mill CPUID
  powercap/intel_rapl: fix and tidy up error handling
  powercap/intel_rapl: Track active CPUs internally
  powercap/intel_rapl: Cleanup duplicated init code
  powercap/intel rapl: Convert to hotplug state machine
  powercap/intel_rapl: Propagate error code when registration fails
  powercap/intel_rapl: Add missing domain data update on hotplug

Documentation/ABI/testing/sysfs-power

@@ -7,30 +7,35 @@ Description:
 		subsystem.
 
 What:		/sys/power/state
-Date:		May 2014
+Date:		November 2016
 Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
 Description:
 		The /sys/power/state file controls system sleep states.
 		Reading from this file returns the available sleep state
-		labels, which may be "mem", "standby", "freeze" and "disk"
-		(hibernation).  The meanings of the first three labels depend on
-		the relative_sleep_states command line argument as follows:
-		 1) relative_sleep_states = 1
-		    "mem", "standby", "freeze" represent non-hibernation sleep
-		    states from the deepest ("mem", always present) to the
-		    shallowest ("freeze").  "standby" and "freeze" may or may
-		    not be present depending on the capabilities of the
-		    platform.  "freeze" can only be present if "standby" is
-		    present.
-		 2) relative_sleep_states = 0 (default)
-		    "mem" - "suspend-to-RAM", present if supported.
-		    "standby" - "power-on suspend", present if supported.
-		    "freeze" - "suspend-to-idle", always present.
-
-		Writing to this file one of these strings causes the system to
-		transition into the corresponding state, if available.  See
-		Documentation/power/states.txt for a description of what
-		"suspend-to-RAM", "power-on suspend" and "suspend-to-idle" mean.
+		labels, which may be "mem" (suspend), "standby" (power-on
+		suspend), "freeze" (suspend-to-idle) and "disk" (hibernation).
+
+		Writing one of the above strings to this file causes the system
+		to transition into the corresponding state, if available.
+
+		See Documentation/power/states.txt for more information.
+
+What:		/sys/power/mem_sleep
+Date:		November 2016
+Contact:	Rafael J. Wysocki <rjw@rjwysocki.net>
+Description:
+		The /sys/power/mem_sleep file controls the operating mode of
+		system suspend.  Reading from it returns the available modes
+		as "s2idle" (always present), "shallow" and "deep" (present if
+		supported).  The mode that will be used on subsequent attempts
+		to suspend the system (by writing "mem" to the /sys/power/state
+		file described above) is enclosed in square brackets.
+
+		Writing one of the above strings to this file causes the mode
+		represented by it to be used on subsequent attempts to suspend
+		the system.
+
+		See Documentation/power/states.txt for more information.
 
 What:		/sys/power/disk
 Date:		September 2006

Documentation/kernel-parameters.txt

@@ -2334,6 +2334,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			memory contents and reserves bad memory
 			regions that are detected.
 
+	mem_sleep_default=	[SUSPEND] Default system suspend mode:
+			s2idle  - Suspend-To-Idle
+			shallow - Power-On Suspend or equivalent (if supported)
+			deep    - Suspend-To-RAM or equivalent (if supported)
+			See Documentation/power/states.txt.
+
 	meye.*=		[HW] Set MotionEye Camera parameters
 			See Documentation/video4linux/meye.txt.
 
@@ -3677,13 +3683,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			[KNL, SMP] Set scheduler's default relax_domain_level.
 			See Documentation/cgroup-v1/cpusets.txt.
 
-	relative_sleep_states=
-			[SUSPEND] Use sleep state labeling where the deepest
-			state available other than hibernation is always "mem".
-			Format: { "0" | "1" }
-			0 -- Traditional sleep state labels.
-			1 -- Relative sleep state labels.
-
 	reserve=	[KNL,BUGS] Force the kernel to ignore some iomem area
 
 	reservetop=	[X86-32]

Documentation/power/states.txt

@@ -8,25 +8,43 @@ for each state.
 
 The states are represented by strings that can be read or written to the
 /sys/power/state file.  Those strings may be "mem", "standby", "freeze" and
-"disk", where the last one always represents hibernation (Suspend-To-Disk) and
-the meaning of the remaining ones depends on the relative_sleep_states command
-line argument.
-
-For relative_sleep_states=1, the strings "mem", "standby" and "freeze" label the
-available non-hibernation sleep states from the deepest to the shallowest,
-respectively.  In that case, "mem" is always present in /sys/power/state,
-because there is at least one non-hibernation sleep state in every system.  If
-the given system supports two non-hibernation sleep states, "standby" is present
-in /sys/power/state in addition to "mem".  If the system supports three
-non-hibernation sleep states, "freeze" will be present in /sys/power/state in
-addition to "mem" and "standby".
-
-For relative_sleep_states=0, which is the default, the following descriptions
-apply.
-
-state:		Suspend-To-Idle
+"disk", where the last three always represent Power-On Suspend (if supported),
+Suspend-To-Idle and hibernation (Suspend-To-Disk), respectively.
+
+The meaning of the "mem" string is controlled by the /sys/power/mem_sleep file.
+It contains strings representing the available modes of system suspend that may
+be triggered by writing "mem" to /sys/power/state.  These modes are "s2idle"
+(Suspend-To-Idle), "shallow" (Power-On Suspend) and "deep" (Suspend-To-RAM).
+The "s2idle" mode is always available, while the other ones are only available
+if supported by the platform (if not supported, the strings representing them
+are not present in /sys/power/mem_sleep).  The string representing the suspend
+mode to be used subsequently is enclosed in square brackets.  Writing one of
+the other strings present in /sys/power/mem_sleep to it causes the suspend mode
+to be used subsequently to change to the one represented by that string.
+
+Consequently, there are two ways to cause the system to go into the
+Suspend-To-Idle sleep state.  The first one is to write "freeze" directly to
+/sys/power/state.  The second one is to write "s2idle" to /sys/power/mem_sleep
+and then to wrtie "mem" to /sys/power/state.  Similarly, there are two ways
+to cause the system to go into the Power-On Suspend sleep state (the strings to
+write to the control files in that case are "standby" or "shallow" and "mem",
+respectively) if that state is supported by the platform.  In turn, there is
+only one way to cause the system to go into the Suspend-To-RAM state (write
+"deep" into /sys/power/mem_sleep and "mem" into /sys/power/state).
+
+The default suspend mode (ie. the one to be used without writing anything into
+/sys/power/mem_sleep) is either "deep" (if Suspend-To-RAM is supported) or
+"s2idle", but it can be overridden by the value of the "mem_sleep_default"
+parameter in the kernel command line.  On some ACPI-based systems, depending on
+the information in the FADT, the default may be "s2idle" even if Suspend-To-RAM
+is supported.
+
+The properties of all of the sleep states are described below.
+
+
+State:		Suspend-To-Idle
 ACPI state:	S0
-Label:		"freeze"
+Label:		"s2idle" ("freeze")
 
 This state is a generic, pure software, light-weight, system sleep state.
 It allows more energy to be saved relative to runtime idle by freezing user
@@ -35,13 +53,13 @@ lower-power than available at run time), such that the processors can
 spend more time in their idle states.
 
 This state can be used for platforms without Power-On Suspend/Suspend-to-RAM
-support, or it can be used in addition to Suspend-to-RAM (memory sleep)
-to provide reduced resume latency.  It is always supported.
+support, or it can be used in addition to Suspend-to-RAM to provide reduced
+resume latency.  It is always supported.
 
 
 State:		Standby / Power-On Suspend
 ACPI State:	S1
-Label:		"standby"
+Label:		"shallow" ("standby")
 
 This state, if supported, offers moderate, though real, power savings, while
 providing a relatively low-latency transition back to a working system.  No
@@ -58,7 +76,7 @@ state.
 
 State:		Suspend-to-RAM
 ACPI State:	S3
-Label:		"mem"
+Label:		"deep"
 
 This state, if supported, offers significant power savings as everything in the
 system is put into a low-power state, except for memory, which should be placed

arch/x86/kernel/acpi/wakeup_64.S

@@ -109,6 +109,15 @@ ENTRY(do_suspend_lowlevel)
 	movq	pt_regs_r14(%rax), %r14
 	movq	pt_regs_r15(%rax), %r15
 
+#ifdef CONFIG_KASAN
+	/*
+	 * The suspend path may have poisoned some areas deeper in the stack,
+	 * which we now need to unpoison.
+	 */
+	movq	%rsp, %rdi
+	call	kasan_unpoison_task_stack_below
+#endif
+
 	xorl	%eax, %eax
 	addq	$8, %rsp
 	FRAME_END

arch/x86/power/hibernate_64.c

@@ -11,6 +11,10 @@
 #include <linux/gfp.h>
 #include <linux/smp.h>
 #include <linux/suspend.h>
+#include <linux/scatterlist.h>
+#include <linux/kdebug.h>
+
+#include <crypto/hash.h>
 
 #include <asm/init.h>
 #include <asm/proto.h>
@@ -177,14 +181,86 @@ int pfn_is_nosave(unsigned long pfn)
 	return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
 }
 
+#define MD5_DIGEST_SIZE 16
+
 struct restore_data_record {
 	unsigned long jump_address;
 	unsigned long jump_address_phys;
 	unsigned long cr3;
 	unsigned long magic;
+	u8 e820_digest[MD5_DIGEST_SIZE];
 };
 
-#define RESTORE_MAGIC	0x123456789ABCDEF0UL
+#define RESTORE_MAGIC	0x23456789ABCDEF01UL
+
+#if IS_BUILTIN(CONFIG_CRYPTO_MD5)
+/**
+ * get_e820_md5 - calculate md5 according to given e820 map
+ *
+ * @map: the e820 map to be calculated
+ * @buf: the md5 result to be stored to
+ */
+static int get_e820_md5(struct e820map *map, void *buf)
+{
+	struct scatterlist sg;
+	struct crypto_ahash *tfm;
+	int size;
+	int ret = 0;
+
+	tfm = crypto_alloc_ahash("md5", 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(tfm))
+		return -ENOMEM;
+
+	{
+		AHASH_REQUEST_ON_STACK(req, tfm);
+		size = offsetof(struct e820map, map)
+			+ sizeof(struct e820entry) * map->nr_map;
+		ahash_request_set_tfm(req, tfm);
+		sg_init_one(&sg, (u8 *)map, size);
+		ahash_request_set_callback(req, 0, NULL, NULL);
+		ahash_request_set_crypt(req, &sg, buf, size);
+
+		if (crypto_ahash_digest(req))
+			ret = -EINVAL;
+		ahash_request_zero(req);
+	}
+	crypto_free_ahash(tfm);
+
+	return ret;
+}
+
+static void hibernation_e820_save(void *buf)
+{
+	get_e820_md5(e820_saved, buf);
+}
+
+static bool hibernation_e820_mismatch(void *buf)
+{
+	int ret;
+	u8 result[MD5_DIGEST_SIZE];
+
+	memset(result, 0, MD5_DIGEST_SIZE);
+	/* If there is no digest in suspend kernel, let it go. */
+	if (!memcmp(result, buf, MD5_DIGEST_SIZE))
+		return false;
+
+	ret = get_e820_md5(e820_saved, result);
+	if (ret)
+		return true;
+
+	return memcmp(result, buf, MD5_DIGEST_SIZE) ? true : false;
+}
+#else
+static void hibernation_e820_save(void *buf)
+{
+}
+
+static bool hibernation_e820_mismatch(void *buf)
+{
+	/* If md5 is not builtin for restore kernel, let it go. */
+	return false;
+}
+#endif
 
 /**
  *	arch_hibernation_header_save - populate the architecture specific part
@@ -201,6 +277,9 @@ int arch_hibernation_header_save(void *addr, unsigned int max_size)
 	rdr->jump_address_phys = __pa_symbol(&restore_registers);
 	rdr->cr3 = restore_cr3;
 	rdr->magic = RESTORE_MAGIC;
+
+	hibernation_e820_save(rdr->e820_digest);
+
 	return 0;
 }
 
@@ -216,5 +295,16 @@ int arch_hibernation_header_restore(void *addr)
 	restore_jump_address = rdr->jump_address;
 	jump_address_phys = rdr->jump_address_phys;
 	restore_cr3 = rdr->cr3;
-	return (rdr->magic == RESTORE_MAGIC) ? 0 : -EINVAL;
+
+	if (rdr->magic != RESTORE_MAGIC) {
+		pr_crit("Unrecognized hibernate image header format!\n");
+		return -EINVAL;
+	}
+
+	if (hibernation_e820_mismatch(rdr->e820_digest)) {
+		pr_crit("Hibernate inconsistent memory map detected!\n");
+		return -ENODEV;
+	}
+
+	return 0;
 }

drivers/acpi/sleep.c

@@ -674,6 +674,14 @@ static void acpi_sleep_suspend_setup(void)
 		if (acpi_sleep_state_supported(i))
 			sleep_states[i] = 1;
 
+	/*
+	 * Use suspend-to-idle by default if ACPI_FADT_LOW_POWER_S0 is set and
+	 * the default suspend mode was not selected from the command line.
+	 */
+	if (acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0 &&
+	    mem_sleep_default > PM_SUSPEND_MEM)
+		mem_sleep_default = PM_SUSPEND_FREEZE;
+
 	suspend_set_ops(old_suspend_ordering ?
 		&acpi_suspend_ops_old : &acpi_suspend_ops);
 	freeze_set_ops(&acpi_freeze_ops);

drivers/base/power/wakeup.c

@@ -811,7 +811,7 @@ void pm_print_active_wakeup_sources(void)
 	rcu_read_lock();
 	list_for_each_entry_rcu(ws, &wakeup_sources, entry) {
 		if (ws->active) {
-			pr_info("active wakeup source: %s\n", ws->name);
+			pr_debug("active wakeup source: %s\n", ws->name);
 			active = 1;
 		} else if (!active &&
 			   (!last_activity_ws ||
@@ -822,7 +822,7 @@ void pm_print_active_wakeup_sources(void)
 	}
 
 	if (!active && last_activity_ws)
-		pr_info("last active wakeup source: %s\n",
+		pr_debug("last active wakeup source: %s\n",
 			last_activity_ws->name);
 	rcu_read_unlock();
 }
@@ -905,7 +905,7 @@ bool pm_get_wakeup_count(unsigned int *count, bool block)
 			split_counters(&cnt, &inpr);
 			if (inpr == 0 || signal_pending(current))
 				break;
-
+			pm_print_active_wakeup_sources();
 			schedule();
 		}
 		finish_wait(&wakeup_count_wait_queue, &wait);

include/linux/suspend.h

@@ -194,6 +194,8 @@ struct platform_freeze_ops {
 };
 
 #ifdef CONFIG_SUSPEND
+extern suspend_state_t mem_sleep_default;
+
 /**
  * suspend_set_ops - set platform dependent suspend operations
  * @ops: The new suspend operations to set.

kernel/power/main.c

@@ -78,6 +78,78 @@ static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
 
 power_attr(pm_async);
 
+#ifdef CONFIG_SUSPEND
+static ssize_t mem_sleep_show(struct kobject *kobj, struct kobj_attribute *attr,
+			      char *buf)
+{
+	char *s = buf;
+	suspend_state_t i;
+
+	for (i = PM_SUSPEND_MIN; i < PM_SUSPEND_MAX; i++)
+		if (mem_sleep_states[i]) {
+			const char *label = mem_sleep_states[i];
+
+			if (mem_sleep_current == i)
+				s += sprintf(s, "[%s] ", label);
+			else
+				s += sprintf(s, "%s ", label);
+		}
+
+	/* Convert the last space to a newline if needed. */
+	if (s != buf)
+		*(s-1) = '\n';
+
+	return (s - buf);
+}
+
+static suspend_state_t decode_suspend_state(const char *buf, size_t n)
+{
+	suspend_state_t state;
+	char *p;
+	int len;
+
+	p = memchr(buf, '\n', n);
+	len = p ? p - buf : n;
+
+	for (state = PM_SUSPEND_MIN; state < PM_SUSPEND_MAX; state++) {
+		const char *label = mem_sleep_states[state];
+
+		if (label && len == strlen(label) && !strncmp(buf, label, len))
+			return state;
+	}
+
+	return PM_SUSPEND_ON;
+}
+
+static ssize_t mem_sleep_store(struct kobject *kobj, struct kobj_attribute *attr,
+			       const char *buf, size_t n)
+{
+	suspend_state_t state;
+	int error;
+
+	error = pm_autosleep_lock();
+	if (error)
+		return error;
+
+	if (pm_autosleep_state() > PM_SUSPEND_ON) {
+		error = -EBUSY;
+		goto out;
+	}
+
+	state = decode_suspend_state(buf, n);
+	if (state < PM_SUSPEND_MAX && state > PM_SUSPEND_ON)
+		mem_sleep_current = state;
+	else
+		error = -EINVAL;
+
+ out:
+	pm_autosleep_unlock();
+	return error ? error : n;
+}
+
+power_attr(mem_sleep);
+#endif /* CONFIG_SUSPEND */
+
 #ifdef CONFIG_PM_DEBUG
 int pm_test_level = TEST_NONE;
 
@@ -368,12 +440,16 @@ static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
 	}
 
 	state = decode_state(buf, n);
-	if (state < PM_SUSPEND_MAX)
+	if (state < PM_SUSPEND_MAX) {
+		if (state == PM_SUSPEND_MEM)
+			state = mem_sleep_current;
+
 		error = pm_suspend(state);
-	else if (state == PM_SUSPEND_MAX)
+	} else if (state == PM_SUSPEND_MAX) {
 		error = hibernate();
-	else
+	} else {
 		error = -EINVAL;
+	}
 
  out:
 	pm_autosleep_unlock();
@@ -485,6 +561,9 @@ static ssize_t autosleep_store(struct kobject *kobj,
 	    && strcmp(buf, "off") && strcmp(buf, "off\n"))
 		return -EINVAL;
 
+	if (state == PM_SUSPEND_MEM)
+		state = mem_sleep_current;
+
 	error = pm_autosleep_set_state(state);
 	return error ? error : n;
 }
@@ -602,6 +681,9 @@ static struct attribute * g[] = {
 #ifdef CONFIG_PM_SLEEP
 	&pm_async_attr.attr,
 	&wakeup_count_attr.attr,
+#ifdef CONFIG_SUSPEND
+	&mem_sleep_attr.attr,
+#endif
 #ifdef CONFIG_PM_AUTOSLEEP
 	&autosleep_attr.attr,
 #endif

kernel/power/power.h

@@ -189,11 +189,15 @@ extern void swsusp_show_speed(ktime_t, ktime_t, unsigned int, char *);
 
 #ifdef CONFIG_SUSPEND
 /* kernel/power/suspend.c */
-extern const char *pm_labels[];
+extern const char * const pm_labels[];
 extern const char *pm_states[];
+extern const char *mem_sleep_states[];
+extern suspend_state_t mem_sleep_current;
 
 extern int suspend_devices_and_enter(suspend_state_t state);
 #else /* !CONFIG_SUSPEND */
+#define mem_sleep_current	PM_SUSPEND_ON
+
 static inline int suspend_devices_and_enter(suspend_state_t state)
 {
 	return -ENOSYS;

kernel/power/suspend.c

@@ -32,8 +32,21 @@
 
 #include "power.h"
 
-const char *pm_labels[] = { "mem", "standby", "freeze", NULL };
+const char * const pm_labels[] = {
+	[PM_SUSPEND_FREEZE] = "freeze",
+	[PM_SUSPEND_STANDBY] = "standby",
+	[PM_SUSPEND_MEM] = "mem",
+};
 const char *pm_states[PM_SUSPEND_MAX];
+static const char * const mem_sleep_labels[] = {
+	[PM_SUSPEND_FREEZE] = "s2idle",
+	[PM_SUSPEND_STANDBY] = "shallow",
+	[PM_SUSPEND_MEM] = "deep",
+};
+const char *mem_sleep_states[PM_SUSPEND_MAX];
+
+suspend_state_t mem_sleep_current = PM_SUSPEND_FREEZE;
+suspend_state_t mem_sleep_default = PM_SUSPEND_MAX;
 
 unsigned int pm_suspend_global_flags;
 EXPORT_SYMBOL_GPL(pm_suspend_global_flags);
@@ -110,30 +123,32 @@ static bool valid_state(suspend_state_t state)
 	return suspend_ops && suspend_ops->valid && suspend_ops->valid(state);
 }
 
-/*
- * If this is set, the "mem" label always corresponds to the deepest sleep state
- * available, the "standby" label corresponds to the second deepest sleep state
- * available (if any), and the "freeze" label corresponds to the remaining
- * available sleep state (if there is one).
- */
-static bool relative_states;
-
 void __init pm_states_init(void)
 {
+	/* "mem" and "freeze" are always present in /sys/power/state. */
+	pm_states[PM_SUSPEND_MEM] = pm_labels[PM_SUSPEND_MEM];
+	pm_states[PM_SUSPEND_FREEZE] = pm_labels[PM_SUSPEND_FREEZE];
 	/*
-	 * freeze state should be supported even without any suspend_ops,
-	 * initialize pm_states accordingly here
+	 * Suspend-to-idle should be supported even without any suspend_ops,
+	 * initialize mem_sleep_states[] accordingly here.
 	 */
-	pm_states[PM_SUSPEND_FREEZE] = pm_labels[relative_states ? 0 : 2];
+	mem_sleep_states[PM_SUSPEND_FREEZE] = mem_sleep_labels[PM_SUSPEND_FREEZE];
 }
 
-static int __init sleep_states_setup(char *str)
+static int __init mem_sleep_default_setup(char *str)
 {
-	relative_states = !strncmp(str, "1", 1);
+	suspend_state_t state;
+
+	for (state = PM_SUSPEND_FREEZE; state <= PM_SUSPEND_MEM; state++)
+		if (mem_sleep_labels[state] &&
+		    !strcmp(str, mem_sleep_labels[state])) {
+			mem_sleep_default = state;
+			break;
+		}
+
 	return 1;
 }
-
-__setup("relative_sleep_states=", sleep_states_setup);
+__setup("mem_sleep_default=", mem_sleep_default_setup);
 
 /**
  * suspend_set_ops - Set the global suspend method table.
@@ -141,21 +156,21 @@ __setup("relative_sleep_states=", sleep_states_setup);
  */
 void suspend_set_ops(const struct platform_suspend_ops *ops)
 {
-	suspend_state_t i;
-	int j = 0;
-
 	lock_system_sleep();
 
 	suspend_ops = ops;
-	for (i = PM_SUSPEND_MEM; i >= PM_SUSPEND_STANDBY; i--)
-		if (valid_state(i)) {
-			pm_states[i] = pm_labels[j++];
-		} else if (!relative_states) {
-			pm_states[i] = NULL;
-			j++;
-		}
 
-	pm_states[PM_SUSPEND_FREEZE] = pm_labels[j];
+	if (valid_state(PM_SUSPEND_STANDBY)) {
+		mem_sleep_states[PM_SUSPEND_STANDBY] = mem_sleep_labels[PM_SUSPEND_STANDBY];
+		pm_states[PM_SUSPEND_STANDBY] = pm_labels[PM_SUSPEND_STANDBY];
+		if (mem_sleep_default == PM_SUSPEND_STANDBY)
+			mem_sleep_current = PM_SUSPEND_STANDBY;
+	}
+	if (valid_state(PM_SUSPEND_MEM)) {
+		mem_sleep_states[PM_SUSPEND_MEM] = mem_sleep_labels[PM_SUSPEND_MEM];
+		if (mem_sleep_default >= PM_SUSPEND_MEM)
+			mem_sleep_current = PM_SUSPEND_MEM;
+	}
 
 	unlock_system_sleep();
 }

mm/kasan/kasan.c

@@ -80,7 +80,14 @@ void kasan_unpoison_task_stack(struct task_struct *task)
 /* Unpoison the stack for the current task beyond a watermark sp value. */
 asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
 {
-	__kasan_unpoison_stack(current, watermark);
+	/*
+	 * Calculate the task stack base address.  Avoid using 'current'
+	 * because this function is called by early resume code which hasn't
+	 * yet set up the percpu register (%gs).
+	 */
+	void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
+
+	kasan_unpoison_shadow(base, watermark - base);
 }
 
 /*