perf/x86: Move perf_event.c ............... => x86/events/core.c

Also, keep the churn at minimum by adjusting the include "perf_event.h"
when each file gets moved.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/1454947748-28629-2-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 2430 insertions, 0 deletions

diff --git a/arch/x86/events/Makefile b/arch/x86/events/Makefile
new file mode 100644
index 000000000000..3fad3ce1bbab
--- /dev/null
+++ b/arch/x86/events/Makefile
@@ -0,0 +1 @@
+obj-y			+= core.o
diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
new file mode 100644
index 000000000000..90ca601b5d5c
--- /dev/null
+++ b/arch/x86/events/core.c
@@ -0,0 +1,2429 @@
+/*
+ * Performance events x86 architecture code
+ *
+ *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
+ *  Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
+ *  Copyright (C) 2009 Jaswinder Singh Rajput
+ *  Copyright (C) 2009 Advanced Micro Devices, Inc., Robert Richter
+ *  Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra
+ *  Copyright (C) 2009 Intel Corporation, <markus.t.metzger@intel.com>
+ *  Copyright (C) 2009 Google, Inc., Stephane Eranian
+ *
+ *  For licencing details see kernel-base/COPYING
+ */
+
+#include <linux/perf_event.h>
+#include <linux/capability.h>
+#include <linux/notifier.h>
+#include <linux/hardirq.h>
+#include <linux/kprobes.h>
+#include <linux/module.h>
+#include <linux/kdebug.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/cpu.h>
+#include <linux/bitops.h>
+#include <linux/device.h>
+
+#include <asm/apic.h>
+#include <asm/stacktrace.h>
+#include <asm/nmi.h>
+#include <asm/smp.h>
+#include <asm/alternative.h>
+#include <asm/mmu_context.h>
+#include <asm/tlbflush.h>
+#include <asm/timer.h>
+#include <asm/desc.h>
+#include <asm/ldt.h>
+
+#include "../kernel/cpu/perf_event.h"
+
+struct x86_pmu x86_pmu __read_mostly;
+
+DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events) = {
+	.enabled = 1,
+};
+
+struct static_key rdpmc_always_available = STATIC_KEY_INIT_FALSE;
+
+u64 __read_mostly hw_cache_event_ids
+				[PERF_COUNT_HW_CACHE_MAX]
+				[PERF_COUNT_HW_CACHE_OP_MAX]
+				[PERF_COUNT_HW_CACHE_RESULT_MAX];
+u64 __read_mostly hw_cache_extra_regs
+				[PERF_COUNT_HW_CACHE_MAX]
+				[PERF_COUNT_HW_CACHE_OP_MAX]
+				[PERF_COUNT_HW_CACHE_RESULT_MAX];
+
+/*
+ * Propagate event elapsed time into the generic event.
+ * Can only be executed on the CPU where the event is active.
+ * Returns the delta events processed.
+ */
+u64 x86_perf_event_update(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	int shift = 64 - x86_pmu.cntval_bits;
+	u64 prev_raw_count, new_raw_count;
+	int idx = hwc->idx;
+	s64 delta;
+
+	if (idx == INTEL_PMC_IDX_FIXED_BTS)
+		return 0;
+
+	/*
+	 * Careful: an NMI might modify the previous event value.
+	 *
+	 * Our tactic to handle this is to first atomically read and
+	 * exchange a new raw count - then add that new-prev delta
+	 * count to the generic event atomically:
+	 */
+again:
+	prev_raw_count = local64_read(&hwc->prev_count);
+	rdpmcl(hwc->event_base_rdpmc, new_raw_count);
+
+	if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
+					new_raw_count) != prev_raw_count)
+		goto again;
+
+	/*
+	 * Now we have the new raw value and have updated the prev
+	 * timestamp already. We can now calculate the elapsed delta
+	 * (event-)time and add that to the generic event.
+	 *
+	 * Careful, not all hw sign-extends above the physical width
+	 * of the count.
+	 */
+	delta = (new_raw_count << shift) - (prev_raw_count << shift);
+	delta >>= shift;
+
+	local64_add(delta, &event->count);
+	local64_sub(delta, &hwc->period_left);
+
+	return new_raw_count;
+}
+
+/*
+ * Find and validate any extra registers to set up.
+ */
+static int x86_pmu_extra_regs(u64 config, struct perf_event *event)
+{
+	struct hw_perf_event_extra *reg;
+	struct extra_reg *er;
+
+	reg = &event->hw.extra_reg;
+
+	if (!x86_pmu.extra_regs)
+		return 0;
+
+	for (er = x86_pmu.extra_regs; er->msr; er++) {
+		if (er->event != (config & er->config_mask))
+			continue;
+		if (event->attr.config1 & ~er->valid_mask)
+			return -EINVAL;
+		/* Check if the extra msrs can be safely accessed*/
+		if (!er->extra_msr_access)
+			return -ENXIO;
+
+		reg->idx = er->idx;
+		reg->config = event->attr.config1;
+		reg->reg = er->msr;
+		break;
+	}
+	return 0;
+}
+
+static atomic_t active_events;
+static atomic_t pmc_refcount;
+static DEFINE_MUTEX(pmc_reserve_mutex);
+
+#ifdef CONFIG_X86_LOCAL_APIC
+
+static bool reserve_pmc_hardware(void)
+{
+	int i;
+
+	for (i = 0; i < x86_pmu.num_counters; i++) {
+		if (!reserve_perfctr_nmi(x86_pmu_event_addr(i)))
+			goto perfctr_fail;
+	}
+
+	for (i = 0; i < x86_pmu.num_counters; i++) {
+		if (!reserve_evntsel_nmi(x86_pmu_config_addr(i)))
+			goto eventsel_fail;
+	}
+
+	return true;
+
+eventsel_fail:
+	for (i--; i >= 0; i--)
+		release_evntsel_nmi(x86_pmu_config_addr(i));
+
+	i = x86_pmu.num_counters;
+
+perfctr_fail:
+	for (i--; i >= 0; i--)
+		release_perfctr_nmi(x86_pmu_event_addr(i));
+
+	return false;
+}
+
+static void release_pmc_hardware(void)
+{
+	int i;
+
+	for (i = 0; i < x86_pmu.num_counters; i++) {
+		release_perfctr_nmi(x86_pmu_event_addr(i));
+		release_evntsel_nmi(x86_pmu_config_addr(i));
+	}
+}
+
+#else
+
+static bool reserve_pmc_hardware(void) { return true; }
+static void release_pmc_hardware(void) {}
+
+#endif
+
+static bool check_hw_exists(void)
+{
+	u64 val, val_fail, val_new= ~0;
+	int i, reg, reg_fail, ret = 0;
+	int bios_fail = 0;
+	int reg_safe = -1;
+
+	/*
+	 * Check to see if the BIOS enabled any of the counters, if so
+	 * complain and bail.
+	 */
+	for (i = 0; i < x86_pmu.num_counters; i++) {
+		reg = x86_pmu_config_addr(i);
+		ret = rdmsrl_safe(reg, &val);
+		if (ret)
+			goto msr_fail;
+		if (val & ARCH_PERFMON_EVENTSEL_ENABLE) {
+			bios_fail = 1;
+			val_fail = val;
+			reg_fail = reg;
+		} else {
+			reg_safe = i;
+		}
+	}
+
+	if (x86_pmu.num_counters_fixed) {
+		reg = MSR_ARCH_PERFMON_FIXED_CTR_CTRL;
+		ret = rdmsrl_safe(reg, &val);
+		if (ret)
+			goto msr_fail;
+		for (i = 0; i < x86_pmu.num_counters_fixed; i++) {
+			if (val & (0x03 << i*4)) {
+				bios_fail = 1;
+				val_fail = val;
+				reg_fail = reg;
+			}
+		}
+	}
+
+	/*
+	 * If all the counters are enabled, the below test will always
+	 * fail.  The tools will also become useless in this scenario.
+	 * Just fail and disable the hardware counters.
+	 */
+
+	if (reg_safe == -1) {
+		reg = reg_safe;
+		goto msr_fail;
+	}
+
+	/*
+	 * Read the current value, change it and read it back to see if it
+	 * matches, this is needed to detect certain hardware emulators
+	 * (qemu/kvm) that don't trap on the MSR access and always return 0s.
+	 */
+	reg = x86_pmu_event_addr(reg_safe);
+	if (rdmsrl_safe(reg, &val))
+		goto msr_fail;
+	val ^= 0xffffUL;
+	ret = wrmsrl_safe(reg, val);
+	ret |= rdmsrl_safe(reg, &val_new);
+	if (ret || val != val_new)
+		goto msr_fail;
+
+	/*
+	 * We still allow the PMU driver to operate:
+	 */
+	if (bios_fail) {
+		pr_cont("Broken BIOS detected, complain to your hardware vendor.\n");
+		pr_err(FW_BUG "the BIOS has corrupted hw-PMU resources (MSR %x is %Lx)\n",
+			      reg_fail, val_fail);
+	}
+
+	return true;
+
+msr_fail:
+	pr_cont("Broken PMU hardware detected, using software events only.\n");
+	pr_info("%sFailed to access perfctr msr (MSR %x is %Lx)\n",
+		boot_cpu_has(X86_FEATURE_HYPERVISOR) ? KERN_INFO : KERN_ERR,
+		reg, val_new);
+
+	return false;
+}
+
+static void hw_perf_event_destroy(struct perf_event *event)
+{
+	x86_release_hardware();
+	atomic_dec(&active_events);
+}
+
+void hw_perf_lbr_event_destroy(struct perf_event *event)
+{
+	hw_perf_event_destroy(event);
+
+	/* undo the lbr/bts event accounting */
+	x86_del_exclusive(x86_lbr_exclusive_lbr);
+}
+
+static inline int x86_pmu_initialized(void)
+{
+	return x86_pmu.handle_irq != NULL;
+}
+
+static inline int
+set_ext_hw_attr(struct hw_perf_event *hwc, struct perf_event *event)
+{
+	struct perf_event_attr *attr = &event->attr;
+	unsigned int cache_type, cache_op, cache_result;
+	u64 config, val;
+
+	config = attr->config;
+
+	cache_type = (config >>  0) & 0xff;
+	if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
+		return -EINVAL;
+
+	cache_op = (config >>  8) & 0xff;
+	if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
+		return -EINVAL;
+
+	cache_result = (config >> 16) & 0xff;
+	if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
+		return -EINVAL;
+
+	val = hw_cache_event_ids[cache_type][cache_op][cache_result];
+
+	if (val == 0)
+		return -ENOENT;
+
+	if (val == -1)
+		return -EINVAL;
+
+	hwc->config |= val;
+	attr->config1 = hw_cache_extra_regs[cache_type][cache_op][cache_result];
+	return x86_pmu_extra_regs(val, event);
+}
+
+int x86_reserve_hardware(void)
+{
+	int err = 0;
+
+	if (!atomic_inc_not_zero(&pmc_refcount)) {
+		mutex_lock(&pmc_reserve_mutex);
+		if (atomic_read(&pmc_refcount) == 0) {
+			if (!reserve_pmc_hardware())
+				err = -EBUSY;
+			else
+				reserve_ds_buffers();
+		}
+		if (!err)
+			atomic_inc(&pmc_refcount);
+		mutex_unlock(&pmc_reserve_mutex);
+	}
+
+	return err;
+}
+
+void x86_release_hardware(void)
+{
+	if (atomic_dec_and_mutex_lock(&pmc_refcount, &pmc_reserve_mutex)) {
+		release_pmc_hardware();
+		release_ds_buffers();
+		mutex_unlock(&pmc_reserve_mutex);
+	}
+}
+
+/*
+ * Check if we can create event of a certain type (that no conflicting events
+ * are present).
+ */
+int x86_add_exclusive(unsigned int what)
+{
+	int i;
+
+	if (!atomic_inc_not_zero(&x86_pmu.lbr_exclusive[what])) {
+		mutex_lock(&pmc_reserve_mutex);
+		for (i = 0; i < ARRAY_SIZE(x86_pmu.lbr_exclusive); i++) {
+			if (i != what && atomic_read(&x86_pmu.lbr_exclusive[i]))
+				goto fail_unlock;
+		}
+		atomic_inc(&x86_pmu.lbr_exclusive[what]);
+		mutex_unlock(&pmc_reserve_mutex);
+	}
+
+	atomic_inc(&active_events);
+	return 0;
+
+fail_unlock:
+	mutex_unlock(&pmc_reserve_mutex);
+	return -EBUSY;
+}
+
+void x86_del_exclusive(unsigned int what)
+{
+	atomic_dec(&x86_pmu.lbr_exclusive[what]);
+	atomic_dec(&active_events);
+}
+
+int x86_setup_perfctr(struct perf_event *event)
+{
+	struct perf_event_attr *attr = &event->attr;
+	struct hw_perf_event *hwc = &event->hw;
+	u64 config;
+
+	if (!is_sampling_event(event)) {
+		hwc->sample_period = x86_pmu.max_period;
+		hwc->last_period = hwc->sample_period;
+		local64_set(&hwc->period_left, hwc->sample_period);
+	}
+
+	if (attr->type == PERF_TYPE_RAW)
+		return x86_pmu_extra_regs(event->attr.config, event);
+
+	if (attr->type == PERF_TYPE_HW_CACHE)
+		return set_ext_hw_attr(hwc, event);
+
+	if (attr->config >= x86_pmu.max_events)
+		return -EINVAL;
+
+	/*
+	 * The generic map:
+	 */
+	config = x86_pmu.event_map(attr->config);
+
+	if (config == 0)
+		return -ENOENT;
+
+	if (config == -1LL)
+		return -EINVAL;
+
+	/*
+	 * Branch tracing:
+	 */
+	if (attr->config == PERF_COUNT_HW_BRANCH_INSTRUCTIONS &&
+	    !attr->freq && hwc->sample_period == 1) {
+		/* BTS is not supported by this architecture. */
+		if (!x86_pmu.bts_active)
+			return -EOPNOTSUPP;
+
+		/* BTS is currently only allowed for user-mode. */
+		if (!attr->exclude_kernel)
+			return -EOPNOTSUPP;
+
+		/* disallow bts if conflicting events are present */
+		if (x86_add_exclusive(x86_lbr_exclusive_lbr))
+			return -EBUSY;
+
+		event->destroy = hw_perf_lbr_event_destroy;
+	}
+
+	hwc->config |= config;
+
+	return 0;
+}
+
+/*
+ * check that branch_sample_type is compatible with
+ * settings needed for precise_ip > 1 which implies
+ * using the LBR to capture ALL taken branches at the
+ * priv levels of the measurement
+ */
+static inline int precise_br_compat(struct perf_event *event)
+{
+	u64 m = event->attr.branch_sample_type;
+	u64 b = 0;
+
+	/* must capture all branches */
+	if (!(m & PERF_SAMPLE_BRANCH_ANY))
+		return 0;
+
+	m &= PERF_SAMPLE_BRANCH_KERNEL | PERF_SAMPLE_BRANCH_USER;
+
+	if (!event->attr.exclude_user)
+		b |= PERF_SAMPLE_BRANCH_USER;
+
+	if (!event->attr.exclude_kernel)
+		b |= PERF_SAMPLE_BRANCH_KERNEL;
+
+	/*
+	 * ignore PERF_SAMPLE_BRANCH_HV, not supported on x86
+	 */
+
+	return m == b;
+}
+
+int x86_pmu_hw_config(struct perf_event *event)
+{
+	if (event->attr.precise_ip) {
+		int precise = 0;
+
+		/* Support for constant skid */
+		if (x86_pmu.pebs_active && !x86_pmu.pebs_broken) {
+			precise++;
+
+			/* Support for IP fixup */
+			if (x86_pmu.lbr_nr || x86_pmu.intel_cap.pebs_format >= 2)
+				precise++;
+
+			if (x86_pmu.pebs_prec_dist)
+				precise++;
+		}
+
+		if (event->attr.precise_ip > precise)
+			return -EOPNOTSUPP;
+	}
+	/*
+	 * check that PEBS LBR correction does not conflict with
+	 * whatever the user is asking with attr->branch_sample_type
+	 */
+	if (event->attr.precise_ip > 1 && x86_pmu.intel_cap.pebs_format < 2) {
+		u64 *br_type = &event->attr.branch_sample_type;
+
+		if (has_branch_stack(event)) {
+			if (!precise_br_compat(event))
+				return -EOPNOTSUPP;
+
+			/* branch_sample_type is compatible */
+
+		} else {
+			/*
+			 * user did not specify  branch_sample_type
+			 *
+			 * For PEBS fixups, we capture all
+			 * the branches at the priv level of the
+			 * event.
+			 */
+			*br_type = PERF_SAMPLE_BRANCH_ANY;
+
+			if (!event->attr.exclude_user)
+				*br_type |= PERF_SAMPLE_BRANCH_USER;
+
+			if (!event->attr.exclude_kernel)
+				*br_type |= PERF_SAMPLE_BRANCH_KERNEL;
+		}
+	}
+
+	if (event->attr.branch_sample_type & PERF_SAMPLE_BRANCH_CALL_STACK)
+		event->attach_state |= PERF_ATTACH_TASK_DATA;
+
+	/*
+	 * Generate PMC IRQs:
+	 * (keep 'enabled' bit clear for now)
+	 */
+	event->hw.config = ARCH_PERFMON_EVENTSEL_INT;
+
+	/*
+	 * Count user and OS events unless requested not to
+	 */
+	if (!event->attr.exclude_user)
+		event->hw.config |= ARCH_PERFMON_EVENTSEL_USR;
+	if (!event->attr.exclude_kernel)
+		event->hw.config |= ARCH_PERFMON_EVENTSEL_OS;
+
+	if (event->attr.type == PERF_TYPE_RAW)
+		event->hw.config |= event->attr.config & X86_RAW_EVENT_MASK;
+
+	if (event->attr.sample_period && x86_pmu.limit_period) {
+		if (x86_pmu.limit_period(event, event->attr.sample_period) >
+				event->attr.sample_period)
+			return -EINVAL;
+	}
+
+	return x86_setup_perfctr(event);
+}
+
+/*
+ * Setup the hardware configuration for a given attr_type
+ */
+static int __x86_pmu_event_init(struct perf_event *event)
+{
+	int err;
+
+	if (!x86_pmu_initialized())
+		return -ENODEV;
+
+	err = x86_reserve_hardware();
+	if (err)
+		return err;
+
+	atomic_inc(&active_events);
+	event->destroy = hw_perf_event_destroy;
+
+	event->hw.idx = -1;
+	event->hw.last_cpu = -1;
+	event->hw.last_tag = ~0ULL;
+
+	/* mark unused */
+	event->hw.extra_reg.idx = EXTRA_REG_NONE;
+	event->hw.branch_reg.idx = EXTRA_REG_NONE;
+
+	return x86_pmu.hw_config(event);
+}
+
+void x86_pmu_disable_all(void)
+{
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+	int idx;
+
+	for (idx = 0; idx < x86_pmu.num_counters; idx++) {
+		u64 val;
+
+		if (!test_bit(idx, cpuc->active_mask))
+			continue;
+		rdmsrl(x86_pmu_config_addr(idx), val);
+		if (!(val & ARCH_PERFMON_EVENTSEL_ENABLE))
+			continue;
+		val &= ~ARCH_PERFMON_EVENTSEL_ENABLE;
+		wrmsrl(x86_pmu_config_addr(idx), val);
+	}
+}
+
+static void x86_pmu_disable(struct pmu *pmu)
+{
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+
+	if (!x86_pmu_initialized())
+		return;
+
+	if (!cpuc->enabled)
+		return;
+
+	cpuc->n_added = 0;
+	cpuc->enabled = 0;
+	barrier();
+
+	x86_pmu.disable_all();
+}
+
+void x86_pmu_enable_all(int added)
+{
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+	int idx;
+
+	for (idx = 0; idx < x86_pmu.num_counters; idx++) {
+		struct hw_perf_event *hwc = &cpuc->events[idx]->hw;
+
+		if (!test_bit(idx, cpuc->active_mask))
+			continue;
+
+		__x86_pmu_enable_event(hwc, ARCH_PERFMON_EVENTSEL_ENABLE);
+	}
+}
+
+static struct pmu pmu;
+
+static inline int is_x86_event(struct perf_event *event)
+{
+	return event->pmu == &pmu;
+}
+
+/*
+ * Event scheduler state:
+ *
+ * Assign events iterating over all events and counters, beginning
+ * with events with least weights first. Keep the current iterator
+ * state in struct sched_state.
+ */
+struct sched_state {
+	int	weight;
+	int	event;		/* event index */
+	int	counter;	/* counter index */
+	int	unassigned;	/* number of events to be assigned left */
+	int	nr_gp;		/* number of GP counters used */
+	unsigned long used[BITS_TO_LONGS(X86_PMC_IDX_MAX)];
+};
+
+/* Total max is X86_PMC_IDX_MAX, but we are O(n!) limited */
+#define	SCHED_STATES_MAX	2
+
+struct perf_sched {
+	int			max_weight;
+	int			max_events;
+	int			max_gp;
+	int			saved_states;
+	struct event_constraint	**constraints;
+	struct sched_state	state;
+	struct sched_state	saved[SCHED_STATES_MAX];
+};
+
+/*
+ * Initialize interator that runs through all events and counters.
+ */
+static void perf_sched_init(struct perf_sched *sched, struct event_constraint **constraints,
+			    int num, int wmin, int wmax, int gpmax)
+{
+	int idx;
+
+	memset(sched, 0, sizeof(*sched));
+	sched->max_events	= num;
+	sched->max_weight	= wmax;
+	sched->max_gp		= gpmax;
+	sched->constraints	= constraints;
+
+	for (idx = 0; idx < num; idx++) {
+		if (constraints[idx]->weight == wmin)
+			break;
+	}
+
+	sched->state.event	= idx;		/* start with min weight */
+	sched->state.weight	= wmin;
+	sched->state.unassigned	= num;
+}
+
+static void perf_sched_save_state(struct perf_sched *sched)
+{
+	if (WARN_ON_ONCE(sched->saved_states >= SCHED_STATES_MAX))
+		return;
+
+	sched->saved[sched->saved_states] = sched->state;
+	sched->saved_states++;
+}
+
+static bool perf_sched_restore_state(struct perf_sched *sched)
+{
+	if (!sched->saved_states)
+		return false;
+
+	sched->saved_states--;
+	sched->state = sched->saved[sched->saved_states];
+
+	/* continue with next counter: */
+	clear_bit(sched->state.counter++, sched->state.used);
+
+	return true;
+}
+
+/*
+ * Select a counter for the current event to schedule. Return true on
+ * success.
+ */
+static bool __perf_sched_find_counter(struct perf_sched *sched)
+{
+	struct event_constraint *c;
+	int idx;
+
+	if (!sched->state.unassigned)
+		return false;
+
+	if (sched->state.event >= sched->max_events)
+		return false;
+
+	c = sched->constraints[sched->state.event];
+	/* Prefer fixed purpose counters */
+	if (c->idxmsk64 & (~0ULL << INTEL_PMC_IDX_FIXED)) {
+		idx = INTEL_PMC_IDX_FIXED;
+		for_each_set_bit_from(idx, c->idxmsk, X86_PMC_IDX_MAX) {
+			if (!__test_and_set_bit(idx, sched->state.used))
+				goto done;
+		}
+	}
+
+	/* Grab the first unused counter starting with idx */
+	idx = sched->state.counter;
+	for_each_set_bit_from(idx, c->idxmsk, INTEL_PMC_IDX_FIXED) {
+		if (!__test_and_set_bit(idx, sched->state.used)) {
+			if (sched->state.nr_gp++ >= sched->max_gp)
+				return false;
+
+			goto done;
+		}
+	}
+
+	return false;
+
+done:
+	sched->state.counter = idx;
+
+	if (c->overlap)
+		perf_sched_save_state(sched);
+
+	return true;
+}
+
+static bool perf_sched_find_counter(struct perf_sched *sched)
+{
+	while (!__perf_sched_find_counter(sched)) {
+		if (!perf_sched_restore_state(sched))
+			return false;
+	}
+
+	return true;
+}
+
+/*
+ * Go through all unassigned events and find the next one to schedule.
+ * Take events with the least weight first. Return true on success.
+ */
+static bool perf_sched_next_event(struct perf_sched *sched)
+{
+	struct event_constraint *c;
+
+	if (!sched->state.unassigned || !--sched->state.unassigned)
+		return false;
+
+	do {
+		/* next event */
+		sched->state.event++;
+		if (sched->state.event >= sched->max_events) {
+			/* next weight */
+			sched->state.event = 0;
+			sched->state.weight++;
+			if (sched->state.weight > sched->max_weight)
+				return false;
+		}
+		c = sched->constraints[sched->state.event];
+	} while (c->weight != sched->state.weight);
+
+	sched->state.counter = 0;	/* start with first counter */
+
+	return true;
+}
+
+/*
+ * Assign a counter for each event.
+ */
+int perf_assign_events(struct event_constraint **constraints, int n,
+			int wmin, int wmax, int gpmax, int *assign)
+{
+	struct perf_sched sched;
+
+	perf_sched_init(&sched, constraints, n, wmin, wmax, gpmax);
+
+	do {
+		if (!perf_sched_find_counter(&sched))
+			break;	/* failed */
+		if (assign)
+			assign[sched.state.event] = sched.state.counter;
+	} while (perf_sched_next_event(&sched));
+
+	return sched.state.unassigned;
+}
+EXPORT_SYMBOL_GPL(perf_assign_events);
+
+int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
+{
+	struct event_constraint *c;
+	unsigned long used_mask[BITS_TO_LONGS(X86_PMC_IDX_MAX)];
+	struct perf_event *e;
+	int i, wmin, wmax, unsched = 0;
+	struct hw_perf_event *hwc;
+
+	bitmap_zero(used_mask, X86_PMC_IDX_MAX);
+
+	if (x86_pmu.start_scheduling)
+		x86_pmu.start_scheduling(cpuc);
+
+	for (i = 0, wmin = X86_PMC_IDX_MAX, wmax = 0; i < n; i++) {
+		cpuc->event_constraint[i] = NULL;
+		c = x86_pmu.get_event_constraints(cpuc, i, cpuc->event_list[i]);
+		cpuc->event_constraint[i] = c;
+
+		wmin = min(wmin, c->weight);
+		wmax = max(wmax, c->weight);
+	}
+
+	/*
+	 * fastpath, try to reuse previous register
+	 */
+	for (i = 0; i < n; i++) {
+		hwc = &cpuc->event_list[i]->hw;
+		c = cpuc->event_constraint[i];
+
+		/* never assigned */
+		if (hwc->idx == -1)
+			break;
+
+		/* constraint still honored */
+		if (!test_bit(hwc->idx, c->idxmsk))
+			break;
+
+		/* not already used */
+		if (test_bit(hwc->idx, used_mask))
+			break;
+
+		__set_bit(hwc->idx, used_mask);
+		if (assign)
+			assign[i] = hwc->idx;
+	}
+
+	/* slow path */
+	if (i != n) {
+		int gpmax = x86_pmu.num_counters;
+
+		/*
+		 * Do not allow scheduling of more than half the available
+		 * generic counters.
+		 *
+		 * This helps avoid counter starvation of sibling thread by
+		 * ensuring at most half the counters cannot be in exclusive
+		 * mode. There is no designated counters for the limits. Any
+		 * N/2 counters can be used. This helps with events with
+		 * specific counter constraints.
+		 */
+		if (is_ht_workaround_enabled() && !cpuc->is_fake &&
+		    READ_ONCE(cpuc->excl_cntrs->exclusive_present))
+			gpmax /= 2;
+
+		unsched = perf_assign_events(cpuc->event_constraint, n, wmin,
+					     wmax, gpmax, assign);
+	}
+
+	/*
+	 * In case of success (unsched = 0), mark events as committed,
+	 * so we do not put_constraint() in case new events are added
+	 * and fail to be scheduled
+	 *
+	 * We invoke the lower level commit callback to lock the resource
+	 *
+	 * We do not need to do all of this in case we are called to
+	 * validate an event group (assign == NULL)
+	 */
+	if (!unsched && assign) {
+		for (i = 0; i < n; i++) {
+			e = cpuc->event_list[i];
+			e->hw.flags |= PERF_X86_EVENT_COMMITTED;
+			if (x86_pmu.commit_scheduling)
+				x86_pmu.commit_scheduling(cpuc, i, assign[i]);
+		}
+	} else {
+		for (i = 0; i < n; i++) {
+			e = cpuc->event_list[i];
+			/*
+			 * do not put_constraint() on comitted events,
+			 * because they are good to go
+			 */
+			if ((e->hw.flags & PERF_X86_EVENT_COMMITTED))
+				continue;
+
+			/*
+			 * release events that failed scheduling
+			 */
+			if (x86_pmu.put_event_constraints)
+				x86_pmu.put_event_constraints(cpuc, e);
+		}
+	}
+
+	if (x86_pmu.stop_scheduling)
+		x86_pmu.stop_scheduling(cpuc);
+
+	return unsched ? -EINVAL : 0;
+}
+
+/*
+ * dogrp: true if must collect siblings events (group)
+ * returns total number of events and error code
+ */
+static int collect_events(struct cpu_hw_events *cpuc, struct perf_event *leader, bool dogrp)
+{
+	struct perf_event *event;
+	int n, max_count;
+
+	max_count = x86_pmu.num_counters + x86_pmu.num_counters_fixed;
+
+	/* current number of events already accepted */
+	n = cpuc->n_events;
+
+	if (is_x86_event(leader)) {
+		if (n >= max_count)
+			return -EINVAL;
+		cpuc->event_list[n] = leader;
+		n++;
+	}
+	if (!dogrp)
+		return n;
+
+	list_for_each_entry(event, &leader->sibling_list, group_entry) {
+		if (!is_x86_event(event) ||
+		    event->state <= PERF_EVENT_STATE_OFF)
+			continue;
+
+		if (n >= max_count)
+			return -EINVAL;
+
+		cpuc->event_list[n] = event;
+		n++;
+	}
+	return n;
+}
+
+static inline void x86_assign_hw_event(struct perf_event *event,
+				struct cpu_hw_events *cpuc, int i)
+{
+	struct hw_perf_event *hwc = &event->hw;
+
+	hwc->idx = cpuc->assign[i];
+	hwc->last_cpu = smp_processor_id();
+	hwc->last_tag = ++cpuc->tags[i];
+
+	if (hwc->idx == INTEL_PMC_IDX_FIXED_BTS) {
+		hwc->config_base = 0;
+		hwc->event_base	= 0;
+	} else if (hwc->idx >= INTEL_PMC_IDX_FIXED) {
+		hwc->config_base = MSR_ARCH_PERFMON_FIXED_CTR_CTRL;
+		hwc->event_base = MSR_ARCH_PERFMON_FIXED_CTR0 + (hwc->idx - INTEL_PMC_IDX_FIXED);
+		hwc->event_base_rdpmc = (hwc->idx - INTEL_PMC_IDX_FIXED) | 1<<30;
+	} else {
+		hwc->config_base = x86_pmu_config_addr(hwc->idx);
+		hwc->event_base  = x86_pmu_event_addr(hwc->idx);
+		hwc->event_base_rdpmc = x86_pmu_rdpmc_index(hwc->idx);
+	}
+}
+
+static inline int match_prev_assignment(struct hw_perf_event *hwc,
+					struct cpu_hw_events *cpuc,
+					int i)
+{
+	return hwc->idx == cpuc->assign[i] &&
+		hwc->last_cpu == smp_processor_id() &&
+		hwc->last_tag == cpuc->tags[i];
+}
+
+static void x86_pmu_start(struct perf_event *event, int flags);
+
+static void x86_pmu_enable(struct pmu *pmu)
+{
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+	struct perf_event *event;
+	struct hw_perf_event *hwc;
+	int i, added = cpuc->n_added;
+
+	if (!x86_pmu_initialized())
+		return;
+
+	if (cpuc->enabled)
+		return;
+
+	if (cpuc->n_added) {
+		int n_running = cpuc->n_events - cpuc->n_added;
+		/*
+		 * apply assignment obtained either from
+		 * hw_perf_group_sched_in() or x86_pmu_enable()
+		 *
+		 * step1: save events moving to new counters
+		 */
+		for (i = 0; i < n_running; i++) {
+			event = cpuc->event_list[i];
+			hwc = &event->hw;
+
+			/*
+			 * we can avoid reprogramming counter if:
+			 * - assigned same counter as last time
+			 * - running on same CPU as last time
+			 * - no other event has used the counter since
+			 */
+			if (hwc->idx == -1 ||
+			    match_prev_assignment(hwc, cpuc, i))
+				continue;
+
+			/*
+			 * Ensure we don't accidentally enable a stopped
+			 * counter simply because we rescheduled.
+			 */
+			if (hwc->state & PERF_HES_STOPPED)
+				hwc->state |= PERF_HES_ARCH;
+
+			x86_pmu_stop(event, PERF_EF_UPDATE);
+		}
+
+		/*
+		 * step2: reprogram moved events into new counters
+		 */
+		for (i = 0; i < cpuc->n_events; i++) {
+			event = cpuc->event_list[i];
+			hwc = &event->hw;
+
+			if (!match_prev_assignment(hwc, cpuc, i))
+				x86_assign_hw_event(event, cpuc, i);
+			else if (i < n_running)
+				continue;
+
+			if (hwc->state & PERF_HES_ARCH)
+				continue;
+
+			x86_pmu_start(event, PERF_EF_RELOAD);
+		}
+		cpuc->n_added = 0;
+		perf_events_lapic_init();
+	}
+
+	cpuc->enabled = 1;
+	barrier();
+
+	x86_pmu.enable_all(added);
+}
+
+static DEFINE_PER_CPU(u64 [X86_PMC_IDX_MAX], pmc_prev_left);
+
+/*
+ * Set the next IRQ period, based on the hwc->period_left value.
+ * To be called with the event disabled in hw:
+ */
+int x86_perf_event_set_period(struct perf_event *event)
+{
+	struct hw_perf_event *hwc = &event->hw;
+	s64 left = local64_read(&hwc->period_left);
+	s64 period = hwc->sample_period;
+	int ret = 0, idx = hwc->idx;
+
+	if (idx == INTEL_PMC_IDX_FIXED_BTS)
+		return 0;
+
+	/*
+	 * If we are way outside a reasonable range then just skip forward:
+	 */
+	if (unlikely(left <= -period)) {
+		left = period;
+		local64_set(&hwc->period_left, left);
+		hwc->last_period = period;
+		ret = 1;
+	}
+
+	if (unlikely(left <= 0)) {
+		left += period;
+		local64_set(&hwc->period_left, left);
+		hwc->last_period = period;
+		ret = 1;
+	}
+	/*
+	 * Quirk: certain CPUs dont like it if just 1 hw_event is left:
+	 */
+	if (unlikely(left < 2))
+		left = 2;
+
+	if (left > x86_pmu.max_period)
+		left = x86_pmu.max_period;
+
+	if (x86_pmu.limit_period)
+		left = x86_pmu.limit_period(event, left);
+
+	per_cpu(pmc_prev_left[idx], smp_processor_id()) = left;
+
+	if (!(hwc->flags & PERF_X86_EVENT_AUTO_RELOAD) ||
+	    local64_read(&hwc->prev_count) != (u64)-left) {
+		/*
+		 * The hw event starts counting from this event offset,
+		 * mark it to be able to extra future deltas:
+		 */
+		local64_set(&hwc->prev_count, (u64)-left);
+
+		wrmsrl(hwc->event_base, (u64)(-left) & x86_pmu.cntval_mask);
+	}
+
+	/*
+	 * Due to erratum on certan cpu we need
+	 * a second write to be sure the register
+	 * is updated properly
+	 */
+	if (x86_pmu.perfctr_second_write) {
+		wrmsrl(hwc->event_base,
+			(u64)(-left) & x86_pmu.cntval_mask);
+	}
+
+	perf_event_update_userpage(event);
+
+	return ret;
+}
+
+void x86_pmu_enable_event(struct perf_event *event)
+{
+	if (__this_cpu_read(cpu_hw_events.enabled))
+		__x86_pmu_enable_event(&event->hw,
+				       ARCH_PERFMON_EVENTSEL_ENABLE);
+}
+
+/*
+ * Add a single event to the PMU.
+ *
+ * The event is added to the group of enabled events
+ * but only if it can be scehduled with existing events.
+ */
+static int x86_pmu_add(struct perf_event *event, int flags)
+{
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+	struct hw_perf_event *hwc;
+	int assign[X86_PMC_IDX_MAX];
+	int n, n0, ret;
+
+	hwc = &event->hw;
+
+	n0 = cpuc->n_events;
+	ret = n = collect_events(cpuc, event, false);
+	if (ret < 0)
+		goto out;
+
+	hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
+	if (!(flags & PERF_EF_START))
+		hwc->state |= PERF_HES_ARCH;
+
+	/*
+	 * If group events scheduling transaction was started,
+	 * skip the schedulability test here, it will be performed
+	 * at commit time (->commit_txn) as a whole.
+	 */
+	if (cpuc->txn_flags & PERF_PMU_TXN_ADD)
+		goto done_collect;
+
+	ret = x86_pmu.schedule_events(cpuc, n, assign);
+	if (ret)
+		goto out;
+	/*
+	 * copy new assignment, now we know it is possible
+	 * will be used by hw_perf_enable()
+	 */
+	memcpy(cpuc->assign, assign, n*sizeof(int));
+
+done_collect:
+	/*
+	 * Commit the collect_events() state. See x86_pmu_del() and
+	 * x86_pmu_*_txn().
+	 */
+	cpuc->n_events = n;
+	cpuc->n_added += n - n0;
+	cpuc->n_txn += n - n0;
+
+	ret = 0;
+out:
+	return ret;
+}
+
+static void x86_pmu_start(struct perf_event *event, int flags)
+{
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+	int idx = event->hw.idx;
+
+	if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED)))
+		return;
+
+	if (WARN_ON_ONCE(idx == -1))
+		return;
+
+	if (flags & PERF_EF_RELOAD) {
+		WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
+		x86_perf_event_set_period(event);
+	}
+
+	event->hw.state = 0;
+
+	cpuc->events[idx] = event;
+	__set_bit(idx, cpuc->active_mask);
+	__set_bit(idx, cpuc->running);
+	x86_pmu.enable(event);
+	perf_event_update_userpage(event);
+}
+
+void perf_event_print_debug(void)
+{
+	u64 ctrl, status, overflow, pmc_ctrl, pmc_count, prev_left, fixed;
+	u64 pebs, debugctl;
+	struct cpu_hw_events *cpuc;
+	unsigned long flags;
+	int cpu, idx;
+
+	if (!x86_pmu.num_counters)
+		return;
+
+	local_irq_save(flags);
+
+	cpu = smp_processor_id();
+	cpuc = &per_cpu(cpu_hw_events, cpu);
+
+	if (x86_pmu.version >= 2) {
+		rdmsrl(MSR_CORE_PERF_GLOBAL_CTRL, ctrl);
+		rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, status);
+		rdmsrl(MSR_CORE_PERF_GLOBAL_OVF_CTRL, overflow);
+		rdmsrl(MSR_ARCH_PERFMON_FIXED_CTR_CTRL, fixed);
+
+		pr_info("\n");
+		pr_info("CPU#%d: ctrl:       %016llx\n", cpu, ctrl);
+		pr_info("CPU#%d: status:     %016llx\n", cpu, status);
+		pr_info("CPU#%d: overflow:   %016llx\n", cpu, overflow);
+		pr_info("CPU#%d: fixed:      %016llx\n", cpu, fixed);
+		if (x86_pmu.pebs_constraints) {
+			rdmsrl(MSR_IA32_PEBS_ENABLE, pebs);
+			pr_info("CPU#%d: pebs:       %016llx\n", cpu, pebs);
+		}
+		if (x86_pmu.lbr_nr) {
+			rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
+			pr_info("CPU#%d: debugctl:   %016llx\n", cpu, debugctl);
+		}
+	}
+	pr_info("CPU#%d: active:     %016llx\n", cpu, *(u64 *)cpuc->active_mask);
+
+	for (idx = 0; idx < x86_pmu.num_counters; idx++) {
+		rdmsrl(x86_pmu_config_addr(idx), pmc_ctrl);
+		rdmsrl(x86_pmu_event_addr(idx), pmc_count);
+
+		prev_left = per_cpu(pmc_prev_left[idx], cpu);
+
+		pr_info("CPU#%d:   gen-PMC%d ctrl:  %016llx\n",
+			cpu, idx, pmc_ctrl);
+		pr_info("CPU#%d:   gen-PMC%d count: %016llx\n",
+			cpu, idx, pmc_count);
+		pr_info("CPU#%d:   gen-PMC%d left:  %016llx\n",
+			cpu, idx, prev_left);
+	}
+	for (idx = 0; idx < x86_pmu.num_counters_fixed; idx++) {
+		rdmsrl(MSR_ARCH_PERFMON_FIXED_CTR0 + idx, pmc_count);
+
+		pr_info("CPU#%d: fixed-PMC%d count: %016llx\n",
+			cpu, idx, pmc_count);
+	}
+	local_irq_restore(flags);
+}
+
+void x86_pmu_stop(struct perf_event *event, int flags)
+{
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+	struct hw_perf_event *hwc = &event->hw;
+
+	if (__test_and_clear_bit(hwc->idx, cpuc->active_mask)) {
+		x86_pmu.disable(event);
+		cpuc->events[hwc->idx] = NULL;
+		WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
+		hwc->state |= PERF_HES_STOPPED;
+	}
+
+	if ((flags & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) {
+		/*
+		 * Drain the remaining delta count out of a event
+		 * that we are disabling:
+		 */
+		x86_perf_event_update(event);
+		hwc->state |= PERF_HES_UPTODATE;
+	}
+}
+
+static void x86_pmu_del(struct perf_event *event, int flags)
+{
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+	int i;
+
+	/*
+	 * event is descheduled
+	 */
+	event->hw.flags &= ~PERF_X86_EVENT_COMMITTED;
+
+	/*
+	 * If we're called during a txn, we don't need to do anything.
+	 * The events never got scheduled and ->cancel_txn will truncate
+	 * the event_list.
+	 *
+	 * XXX assumes any ->del() called during a TXN will only be on
+	 * an event added during that same TXN.
+	 */
+	if (cpuc->txn_flags & PERF_PMU_TXN_ADD)
+		return;
+
+	/*
+	 * Not a TXN, therefore cleanup properly.
+	 */
+	x86_pmu_stop(event, PERF_EF_UPDATE);
+
+	for (i = 0; i < cpuc->n_events; i++) {
+		if (event == cpuc->event_list[i])
+			break;
+	}
+
+	if (WARN_ON_ONCE(i == cpuc->n_events)) /* called ->del() without ->add() ? */
+		return;
+
+	/* If we have a newly added event; make sure to decrease n_added. */
+	if (i >= cpuc->n_events - cpuc->n_added)
+		--cpuc->n_added;
+
+	if (x86_pmu.put_event_constraints)
+		x86_pmu.put_event_constraints(cpuc, event);
+
+	/* Delete the array entry. */
+	while (++i < cpuc->n_events) {
+		cpuc->event_list[i-1] = cpuc->event_list[i];
+		cpuc->event_constraint[i-1] = cpuc->event_constraint[i];
+	}
+	--cpuc->n_events;
+
+	perf_event_update_userpage(event);
+}
+
+int x86_pmu_handle_irq(struct pt_regs *regs)
+{
+	struct perf_sample_data data;
+	struct cpu_hw_events *cpuc;
+	struct perf_event *event;
+	int idx, handled = 0;
+	u64 val;
+
+	cpuc = this_cpu_ptr(&cpu_hw_events);
+
+	/*
+	 * Some chipsets need to unmask the LVTPC in a particular spot
+	 * inside the nmi handler.  As a result, the unmasking was pushed
+	 * into all the nmi handlers.
+	 *
+	 * This generic handler doesn't seem to have any issues where the
+	 * unmasking occurs so it was left at the top.
+	 */
+	apic_write(APIC_LVTPC, APIC_DM_NMI);
+
+	for (idx = 0; idx < x86_pmu.num_counters; idx++) {
+		if (!test_bit(idx, cpuc->active_mask)) {
+			/*
+			 * Though we deactivated the counter some cpus
+			 * might still deliver spurious interrupts still
+			 * in flight. Catch them:
+			 */
+			if (__test_and_clear_bit(idx, cpuc->running))
+				handled++;
+			continue;
+		}
+
+		event = cpuc->events[idx];
+
+		val = x86_perf_event_update(event);
+		if (val & (1ULL << (x86_pmu.cntval_bits - 1)))
+			continue;
+
+		/*
+		 * event overflow
+		 */
+		handled++;
+		perf_sample_data_init(&data, 0, event->hw.last_period);
+
+		if (!x86_perf_event_set_period(event))
+			continue;
+
+		if (perf_event_overflow(event, &data, regs))
+			x86_pmu_stop(event, 0);
+	}
+
+	if (handled)
+		inc_irq_stat(apic_perf_irqs);
+
+	return handled;
+}
+
+void perf_events_lapic_init(void)
+{
+	if (!x86_pmu.apic || !x86_pmu_initialized())
+		return;
+
+	/*
+	 * Always use NMI for PMU
+	 */
+	apic_write(APIC_LVTPC, APIC_DM_NMI);
+}
+
+static int
+perf_event_nmi_handler(unsigned int cmd, struct pt_regs *regs)
+{
+	u64 start_clock;
+	u64 finish_clock;
+	int ret;
+
+	/*
+	 * All PMUs/events that share this PMI handler should make sure to
+	 * increment active_events for their events.
+	 */
+	if (!atomic_read(&active_events))
+		return NMI_DONE;
+
+	start_clock = sched_clock();
+	ret = x86_pmu.handle_irq(regs);
+	finish_clock = sched_clock();
+
+	perf_sample_event_took(finish_clock - start_clock);
+
+	return ret;
+}
+NOKPROBE_SYMBOL(perf_event_nmi_handler);
+
+struct event_constraint emptyconstraint;
+struct event_constraint unconstrained;
+
+static int
+x86_pmu_notifier(struct notifier_block *self, unsigned long action, void *hcpu)
+{
+	unsigned int cpu = (long)hcpu;
+	struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
+	int i, ret = NOTIFY_OK;
+
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_UP_PREPARE:
+		for (i = 0 ; i < X86_PERF_KFREE_MAX; i++)
+			cpuc->kfree_on_online[i] = NULL;
+		if (x86_pmu.cpu_prepare)
+			ret = x86_pmu.cpu_prepare(cpu);
+		break;
+
+	case CPU_STARTING:
+		if (x86_pmu.cpu_starting)
+			x86_pmu.cpu_starting(cpu);
+		break;
+
+	case CPU_ONLINE:
+		for (i = 0 ; i < X86_PERF_KFREE_MAX; i++) {
+			kfree(cpuc->kfree_on_online[i]);
+			cpuc->kfree_on_online[i] = NULL;
+		}
+		break;
+
+	case CPU_DYING:
+		if (x86_pmu.cpu_dying)
+			x86_pmu.cpu_dying(cpu);
+		break;
+
+	case CPU_UP_CANCELED:
+	case CPU_DEAD:
+		if (x86_pmu.cpu_dead)
+			x86_pmu.cpu_dead(cpu);
+		break;
+
+	default:
+		break;
+	}
+
+	return ret;
+}
+
+static void __init pmu_check_apic(void)
+{
+	if (cpu_has_apic)
+		return;
+
+	x86_pmu.apic = 0;
+	pr_info("no APIC, boot with the \"lapic\" boot parameter to force-enable it.\n");
+	pr_info("no hardware sampling interrupt available.\n");
+
+	/*
+	 * If we have a PMU initialized but no APIC
+	 * interrupts, we cannot sample hardware
+	 * events (user-space has to fall back and
+	 * sample via a hrtimer based software event):
+	 */
+	pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
+
+}
+
+static struct attribute_group x86_pmu_format_group = {
+	.name = "format",
+	.attrs = NULL,
+};
+
+/*
+ * Remove all undefined events (x86_pmu.event_map(id) == 0)
+ * out of events_attr attributes.
+ */
+static void __init filter_events(struct attribute **attrs)
+{
+	struct device_attribute *d;
+	struct perf_pmu_events_attr *pmu_attr;
+	int offset = 0;
+	int i, j;
+
+	for (i = 0; attrs[i]; i++) {
+		d = (struct device_attribute *)attrs[i];
+		pmu_attr = container_of(d, struct perf_pmu_events_attr, attr);
+		/* str trumps id */
+		if (pmu_attr->event_str)
+			continue;
+		if (x86_pmu.event_map(i + offset))
+			continue;
+
+		for (j = i; attrs[j]; j++)
+			attrs[j] = attrs[j + 1];
+
+		/* Check the shifted attr. */
+		i--;
+
+		/*
+		 * event_map() is index based, the attrs array is organized
+		 * by increasing event index. If we shift the events, then
+		 * we need to compensate for the event_map(), otherwise
+		 * we are looking up the wrong event in the map
+		 */
+		offset++;
+	}
+}
+
+/* Merge two pointer arrays */
+__init struct attribute **merge_attr(struct attribute **a, struct attribute **b)
+{
+	struct attribute **new;
+	int j, i;
+
+	for (j = 0; a[j]; j++)
+		;
+	for (i = 0; b[i]; i++)
+		j++;
+	j++;
+
+	new = kmalloc(sizeof(struct attribute *) * j, GFP_KERNEL);
+	if (!new)
+		return NULL;
+
+	j = 0;
+	for (i = 0; a[i]; i++)
+		new[j++] = a[i];
+	for (i = 0; b[i]; i++)
+		new[j++] = b[i];
+	new[j] = NULL;
+
+	return new;
+}
+
+ssize_t events_sysfs_show(struct device *dev, struct device_attribute *attr,
+			  char *page)
+{
+	struct perf_pmu_events_attr *pmu_attr = \
+		container_of(attr, struct perf_pmu_events_attr, attr);
+	u64 config = x86_pmu.event_map(pmu_attr->id);
+
+	/* string trumps id */
+	if (pmu_attr->event_str)
+		return sprintf(page, "%s", pmu_attr->event_str);
+
+	return x86_pmu.events_sysfs_show(page, config);
+}
+
+EVENT_ATTR(cpu-cycles,			CPU_CYCLES		);
+EVENT_ATTR(instructions,		INSTRUCTIONS		);
+EVENT_ATTR(cache-references,		CACHE_REFERENCES	);
+EVENT_ATTR(cache-misses, 		CACHE_MISSES		);
+EVENT_ATTR(branch-instructions,		BRANCH_INSTRUCTIONS	);
+EVENT_ATTR(branch-misses,		BRANCH_MISSES		);
+EVENT_ATTR(bus-cycles,			BUS_CYCLES		);
+EVENT_ATTR(stalled-cycles-frontend,	STALLED_CYCLES_FRONTEND	);
+EVENT_ATTR(stalled-cycles-backend,	STALLED_CYCLES_BACKEND	);
+EVENT_ATTR(ref-cycles,			REF_CPU_CYCLES		);
+
+static struct attribute *empty_attrs;
+
+static struct attribute *events_attr[] = {
+	EVENT_PTR(CPU_CYCLES),
+	EVENT_PTR(INSTRUCTIONS),
+	EVENT_PTR(CACHE_REFERENCES),
+	EVENT_PTR(CACHE_MISSES),
+	EVENT_PTR(BRANCH_INSTRUCTIONS),
+	EVENT_PTR(BRANCH_MISSES),
+	EVENT_PTR(BUS_CYCLES),
+	EVENT_PTR(STALLED_CYCLES_FRONTEND),
+	EVENT_PTR(STALLED_CYCLES_BACKEND),
+	EVENT_PTR(REF_CPU_CYCLES),
+	NULL,
+};
+
+static struct attribute_group x86_pmu_events_group = {
+	.name = "events",
+	.attrs = events_attr,
+};
+
+ssize_t x86_event_sysfs_show(char *page, u64 config, u64 event)
+{
+	u64 umask  = (config & ARCH_PERFMON_EVENTSEL_UMASK) >> 8;
+	u64 cmask  = (config & ARCH_PERFMON_EVENTSEL_CMASK) >> 24;
+	bool edge  = (config & ARCH_PERFMON_EVENTSEL_EDGE);
+	bool pc    = (config & ARCH_PERFMON_EVENTSEL_PIN_CONTROL);
+	bool any   = (config & ARCH_PERFMON_EVENTSEL_ANY);
+	bool inv   = (config & ARCH_PERFMON_EVENTSEL_INV);
+	ssize_t ret;
+
+	/*
+	* We have whole page size to spend and just little data
+	* to write, so we can safely use sprintf.
+	*/
+	ret = sprintf(page, "event=0x%02llx", event);
+
+	if (umask)
+		ret += sprintf(page + ret, ",umask=0x%02llx", umask);
+
+	if (edge)
+		ret += sprintf(page + ret, ",edge");
+
+	if (pc)
+		ret += sprintf(page + ret, ",pc");
+
+	if (any)
+		ret += sprintf(page + ret, ",any");
+
+	if (inv)
+		ret += sprintf(page + ret, ",inv");
+
+	if (cmask)
+		ret += sprintf(page + ret, ",cmask=0x%02llx", cmask);
+
+	ret += sprintf(page + ret, "\n");
+
+	return ret;
+}
+
+static int __init init_hw_perf_events(void)
+{
+	struct x86_pmu_quirk *quirk;
+	int err;
+
+	pr_info("Performance Events: ");
+
+	switch (boot_cpu_data.x86_vendor) {
+	case X86_VENDOR_INTEL:
+		err = intel_pmu_init();
+		break;
+	case X86_VENDOR_AMD:
+		err = amd_pmu_init();
+		break;
+	default:
+		err = -ENOTSUPP;
+	}
+	if (err != 0) {
+		pr_cont("no PMU driver, software events only.\n");
+		return 0;
+	}
+
+	pmu_check_apic();
+
+	/* sanity check that the hardware exists or is emulated */
+	if (!check_hw_exists())
+		return 0;
+
+	pr_cont("%s PMU driver.\n", x86_pmu.name);
+
+	x86_pmu.attr_rdpmc = 1; /* enable userspace RDPMC usage by default */
+
+	for (quirk = x86_pmu.quirks; quirk; quirk = quirk->next)
+		quirk->func();
+
+	if (!x86_pmu.intel_ctrl)
+		x86_pmu.intel_ctrl = (1 << x86_pmu.num_counters) - 1;
+
+	perf_events_lapic_init();
+	register_nmi_handler(NMI_LOCAL, perf_event_nmi_handler, 0, "PMI");
+
+	unconstrained = (struct event_constraint)
+		__EVENT_CONSTRAINT(0, (1ULL << x86_pmu.num_counters) - 1,
+				   0, x86_pmu.num_counters, 0, 0);
+
+	x86_pmu_format_group.attrs = x86_pmu.format_attrs;
+
+	if (x86_pmu.event_attrs)
+		x86_pmu_events_group.attrs = x86_pmu.event_attrs;
+
+	if (!x86_pmu.events_sysfs_show)
+		x86_pmu_events_group.attrs = &empty_attrs;
+	else
+		filter_events(x86_pmu_events_group.attrs);
+
+	if (x86_pmu.cpu_events) {
+		struct attribute **tmp;
+
+		tmp = merge_attr(x86_pmu_events_group.attrs, x86_pmu.cpu_events);
+		if (!WARN_ON(!tmp))
+			x86_pmu_events_group.attrs = tmp;
+	}
+
+	pr_info("... version:                %d\n",     x86_pmu.version);
+	pr_info("... bit width:              %d\n",     x86_pmu.cntval_bits);
+	pr_info("... generic registers:      %d\n",     x86_pmu.num_counters);
+	pr_info("... value mask:             %016Lx\n", x86_pmu.cntval_mask);
+	pr_info("... max period:             %016Lx\n", x86_pmu.max_period);
+	pr_info("... fixed-purpose events:   %d\n",     x86_pmu.num_counters_fixed);
+	pr_info("... event mask:             %016Lx\n", x86_pmu.intel_ctrl);
+
+	perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW);
+	perf_cpu_notifier(x86_pmu_notifier);
+
+	return 0;
+}
+early_initcall(init_hw_perf_events);
+
+static inline void x86_pmu_read(struct perf_event *event)
+{
+	x86_perf_event_update(event);
+}
+
+/*
+ * Start group events scheduling transaction
+ * Set the flag to make pmu::enable() not perform the
+ * schedulability test, it will be performed at commit time
+ *
+ * We only support PERF_PMU_TXN_ADD transactions. Save the
+ * transaction flags but otherwise ignore non-PERF_PMU_TXN_ADD
+ * transactions.
+ */
+static void x86_pmu_start_txn(struct pmu *pmu, unsigned int txn_flags)
+{
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+
+	WARN_ON_ONCE(cpuc->txn_flags);		/* txn already in flight */
+
+	cpuc->txn_flags = txn_flags;
+	if (txn_flags & ~PERF_PMU_TXN_ADD)
+		return;
+
+	perf_pmu_disable(pmu);
+	__this_cpu_write(cpu_hw_events.n_txn, 0);
+}
+
+/*
+ * Stop group events scheduling transaction
+ * Clear the flag and pmu::enable() will perform the
+ * schedulability test.
+ */
+static void x86_pmu_cancel_txn(struct pmu *pmu)
+{
+	unsigned int txn_flags;
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+
+	WARN_ON_ONCE(!cpuc->txn_flags);	/* no txn in flight */
+
+	txn_flags = cpuc->txn_flags;
+	cpuc->txn_flags = 0;
+	if (txn_flags & ~PERF_PMU_TXN_ADD)
+		return;
+
+	/*
+	 * Truncate collected array by the number of events added in this
+	 * transaction. See x86_pmu_add() and x86_pmu_*_txn().
+	 */
+	__this_cpu_sub(cpu_hw_events.n_added, __this_cpu_read(cpu_hw_events.n_txn));
+	__this_cpu_sub(cpu_hw_events.n_events, __this_cpu_read(cpu_hw_events.n_txn));
+	perf_pmu_enable(pmu);
+}
+
+/*
+ * Commit group events scheduling transaction
+ * Perform the group schedulability test as a whole
+ * Return 0 if success
+ *
+ * Does not cancel the transaction on failure; expects the caller to do this.
+ */
+static int x86_pmu_commit_txn(struct pmu *pmu)
+{
+	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
+	int assign[X86_PMC_IDX_MAX];
+	int n, ret;
+
+	WARN_ON_ONCE(!cpuc->txn_flags);	/* no txn in flight */
+
+	if (cpuc->txn_flags & ~PERF_PMU_TXN_ADD) {
+		cpuc->txn_flags = 0;
+		return 0;
+	}
+
+	n = cpuc->n_events;
+
+	if (!x86_pmu_initialized())
+		return -EAGAIN;
+
+	ret = x86_pmu.schedule_events(cpuc, n, assign);
+	if (ret)
+		return ret;
+
+	/*
+	 * copy new assignment, now we know it is possible
+	 * will be used by hw_perf_enable()
+	 */
+	memcpy(cpuc->assign, assign, n*sizeof(int));
+
+	cpuc->txn_flags = 0;
+	perf_pmu_enable(pmu);
+	return 0;
+}
+/*
+ * a fake_cpuc is used to validate event groups. Due to
+ * the extra reg logic, we need to also allocate a fake
+ * per_core and per_cpu structure. Otherwise, group events
+ * using extra reg may conflict without the kernel being
+ * able to catch this when the last event gets added to
+ * the group.
+ */
+static void free_fake_cpuc(struct cpu_hw_events *cpuc)
+{
+	kfree(cpuc->shared_regs);
+	kfree(cpuc);
+}
+
+static struct cpu_hw_events *allocate_fake_cpuc(void)
+{
+	struct cpu_hw_events *cpuc;
+	int cpu = raw_smp_processor_id();
+
+	cpuc = kzalloc(sizeof(*cpuc), GFP_KERNEL);
+	if (!cpuc)
+		return ERR_PTR(-ENOMEM);
+
+	/* only needed, if we have extra_regs */
+	if (x86_pmu.extra_regs) {
+		cpuc->shared_regs = allocate_shared_regs(cpu);
+		if (!cpuc->shared_regs)
+			goto error;
+	}
+	cpuc->is_fake = 1;
+	return cpuc;
+error:
+	free_fake_cpuc(cpuc);
+	return ERR_PTR(-ENOMEM);
+}
+
+/*
+ * validate that we can schedule this event
+ */
+static int validate_event(struct perf_event *event)
+{
+	struct cpu_hw_events *fake_cpuc;
+	struct event_constraint *c;
+	int ret = 0;
+
+	fake_cpuc = allocate_fake_cpuc();
+	if (IS_ERR(fake_cpuc))
+		return PTR_ERR(fake_cpuc);
+
+	c = x86_pmu.get_event_constraints(fake_cpuc, -1, event);
+
+	if (!c || !c->weight)
+		ret = -EINVAL;
+
+	if (x86_pmu.put_event_constraints)
+		x86_pmu.put_event_constraints(fake_cpuc, event);
+
+	free_fake_cpuc(fake_cpuc);
+
+	return ret;
+}
+
+/*
+ * validate a single event group
+ *
+ * validation include:
+ *	- check events are compatible which each other
+ *	- events do not compete for the same counter
+ *	- number of events <= number of counters
+ *
+ * validation ensures the group can be loaded onto the
+ * PMU if it was the only group available.
+ */
+static int validate_group(struct perf_event *event)
+{
+	struct perf_event *leader = event->group_leader;
+	struct cpu_hw_events *fake_cpuc;
+	int ret = -EINVAL, n;
+
+	fake_cpuc = allocate_fake_cpuc();
+	if (IS_ERR(fake_cpuc))
+		return PTR_ERR(fake_cpuc);
+	/*
+	 * the event is not yet connected with its
+	 * siblings therefore we must first collect
+	 * existing siblings, then add the new event
+	 * before we can simulate the scheduling
+	 */
+	n = collect_events(fake_cpuc, leader, true);
+	if (n < 0)
+		goto out;
+
+	fake_cpuc->n_events = n;
+	n = collect_events(fake_cpuc, event, false);
+	if (n < 0)
+		goto out;
+
+	fake_cpuc->n_events = n;
+
+	ret = x86_pmu.schedule_events(fake_cpuc, n, NULL);
+
+out:
+	free_fake_cpuc(fake_cpuc);
+	return ret;
+}
+
+static int x86_pmu_event_init(struct perf_event *event)
+{
+	struct pmu *tmp;
+	int err;
+
+	switch (event->attr.type) {
+	case PERF_TYPE_RAW:
+	case PERF_TYPE_HARDWARE:
+	case PERF_TYPE_HW_CACHE:
+		break;
+
+	default:
+		return -ENOENT;
+	}
+
+	err = __x86_pmu_event_init(event);
+	if (!err) {
+		/*
+		 * we temporarily connect event to its pmu
+		 * such that validate_group() can classify
+		 * it as an x86 event using is_x86_event()
+		 */
+		tmp = event->pmu;
+		event->pmu = &pmu;
+
+		if (event->group_leader != event)
+			err = validate_group(event);
+		else
+			err = validate_event(event);
+
+		event->pmu = tmp;
+	}
+	if (err) {
+		if (event->destroy)
+			event->destroy(event);
+	}
+
+	if (ACCESS_ONCE(x86_pmu.attr_rdpmc))
+		event->hw.flags |= PERF_X86_EVENT_RDPMC_ALLOWED;
+
+	return err;
+}
+
+static void refresh_pce(void *ignored)
+{
+	if (current->mm)
+		load_mm_cr4(current->mm);
+}
+
+static void x86_pmu_event_mapped(struct perf_event *event)
+{
+	if (!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED))
+		return;
+
+	if (atomic_inc_return(&current->mm->context.perf_rdpmc_allowed) == 1)
+		on_each_cpu_mask(mm_cpumask(current->mm), refresh_pce, NULL, 1);
+}
+
+static void x86_pmu_event_unmapped(struct perf_event *event)
+{
+	if (!current->mm)
+		return;
+
+	if (!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED))
+		return;
+
+	if (atomic_dec_and_test(&current->mm->context.perf_rdpmc_allowed))
+		on_each_cpu_mask(mm_cpumask(current->mm), refresh_pce, NULL, 1);
+}
+
+static int x86_pmu_event_idx(struct perf_event *event)
+{
+	int idx = event->hw.idx;
+
+	if (!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED))
+		return 0;
+
+	if (x86_pmu.num_counters_fixed && idx >= INTEL_PMC_IDX_FIXED) {
+		idx -= INTEL_PMC_IDX_FIXED;
+		idx |= 1 << 30;
+	}
+
+	return idx + 1;
+}
+
+static ssize_t get_attr_rdpmc(struct device *cdev,
+			      struct device_attribute *attr,
+			      char *buf)
+{
+	return snprintf(buf, 40, "%d\n", x86_pmu.attr_rdpmc);
+}
+
+static ssize_t set_attr_rdpmc(struct device *cdev,
+			      struct device_attribute *attr,
+			      const char *buf, size_t count)
+{
+	unsigned long val;
+	ssize_t ret;
+
+	ret = kstrtoul(buf, 0, &val);
+	if (ret)
+		return ret;
+
+	if (val > 2)
+		return -EINVAL;
+
+	if (x86_pmu.attr_rdpmc_broken)
+		return -ENOTSUPP;
+
+	if ((val == 2) != (x86_pmu.attr_rdpmc == 2)) {
+		/*
+		 * Changing into or out of always available, aka
+		 * perf-event-bypassing mode.  This path is extremely slow,
+		 * but only root can trigger it, so it's okay.
+		 */
+		if (val == 2)
+			static_key_slow_inc(&rdpmc_always_available);
+		else
+			static_key_slow_dec(&rdpmc_always_available);
+		on_each_cpu(refresh_pce, NULL, 1);
+	}
+
+	x86_pmu.attr_rdpmc = val;
+
+	return count;
+}
+
+static DEVICE_ATTR(rdpmc, S_IRUSR | S_IWUSR, get_attr_rdpmc, set_attr_rdpmc);
+
+static struct attribute *x86_pmu_attrs[] = {
+	&dev_attr_rdpmc.attr,
+	NULL,
+};
+
+static struct attribute_group x86_pmu_attr_group = {
+	.attrs = x86_pmu_attrs,
+};
+
+static const struct attribute_group *x86_pmu_attr_groups[] = {
+	&x86_pmu_attr_group,
+	&x86_pmu_format_group,
+	&x86_pmu_events_group,
+	NULL,
+};
+
+static void x86_pmu_sched_task(struct perf_event_context *ctx, bool sched_in)
+{
+	if (x86_pmu.sched_task)
+		x86_pmu.sched_task(ctx, sched_in);
+}
+
+void perf_check_microcode(void)
+{
+	if (x86_pmu.check_microcode)
+		x86_pmu.check_microcode();
+}
+EXPORT_SYMBOL_GPL(perf_check_microcode);
+
+static struct pmu pmu = {
+	.pmu_enable		= x86_pmu_enable,
+	.pmu_disable		= x86_pmu_disable,
+
+	.attr_groups		= x86_pmu_attr_groups,
+
+	.event_init		= x86_pmu_event_init,
+
+	.event_mapped		= x86_pmu_event_mapped,
+	.event_unmapped		= x86_pmu_event_unmapped,
+
+	.add			= x86_pmu_add,
+	.del			= x86_pmu_del,
+	.start			= x86_pmu_start,
+	.stop			= x86_pmu_stop,
+	.read			= x86_pmu_read,
+
+	.start_txn		= x86_pmu_start_txn,
+	.cancel_txn		= x86_pmu_cancel_txn,
+	.commit_txn		= x86_pmu_commit_txn,
+
+	.event_idx		= x86_pmu_event_idx,
+	.sched_task		= x86_pmu_sched_task,
+	.task_ctx_size          = sizeof(struct x86_perf_task_context),
+};
+
+void arch_perf_update_userpage(struct perf_event *event,
+			       struct perf_event_mmap_page *userpg, u64 now)
+{
+	struct cyc2ns_data *data;
+
+	userpg->cap_user_time = 0;
+	userpg->cap_user_time_zero = 0;
+	userpg->cap_user_rdpmc =
+		!!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED);
+	userpg->pmc_width = x86_pmu.cntval_bits;
+
+	if (!sched_clock_stable())
+		return;
+
+	data = cyc2ns_read_begin();
+
+	/*
+	 * Internal timekeeping for enabled/running/stopped times
+	 * is always in the local_clock domain.
+	 */
+	userpg->cap_user_time = 1;
+	userpg->time_mult = data->cyc2ns_mul;
+	userpg->time_shift = data->cyc2ns_shift;
+	userpg->time_offset = data->cyc2ns_offset - now;
+
+	/*
+	 * cap_user_time_zero doesn't make sense when we're using a different
+	 * time base for the records.
+	 */
+	if (event->clock == &local_clock) {
+		userpg->cap_user_time_zero = 1;
+		userpg->time_zero = data->cyc2ns_offset;
+	}
+
+	cyc2ns_read_end(data);
+}
+
+/*
+ * callchain support
+ */
+
+static int backtrace_stack(void *data, char *name)
+{
+	return 0;
+}
+
+static void backtrace_address(void *data, unsigned long addr, int reliable)
+{
+	struct perf_callchain_entry *entry = data;
+
+	perf_callchain_store(entry, addr);
+}
+
+static const struct stacktrace_ops backtrace_ops = {
+	.stack			= backtrace_stack,
+	.address		= backtrace_address,
+	.walk_stack		= print_context_stack_bp,
+};
+
+void
+perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
+{
+	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+		/* TODO: We don't support guest os callchain now */
+		return;
+	}
+
+	perf_callchain_store(entry, regs->ip);
+
+	dump_trace(NULL, regs, NULL, 0, &backtrace_ops, entry);
+}
+
+static inline int
+valid_user_frame(const void __user *fp, unsigned long size)
+{
+	return (__range_not_ok(fp, size, TASK_SIZE) == 0);
+}
+
+static unsigned long get_segment_base(unsigned int segment)
+{
+	struct desc_struct *desc;
+	int idx = segment >> 3;
+
+	if ((segment & SEGMENT_TI_MASK) == SEGMENT_LDT) {
+#ifdef CONFIG_MODIFY_LDT_SYSCALL
+		struct ldt_struct *ldt;
+
+		if (idx > LDT_ENTRIES)
+			return 0;
+
+		/* IRQs are off, so this synchronizes with smp_store_release */
+		ldt = lockless_dereference(current->active_mm->context.ldt);
+		if (!ldt || idx > ldt->size)
+			return 0;
+
+		desc = &ldt->entries[idx];
+#else
+		return 0;
+#endif
+	} else {
+		if (idx > GDT_ENTRIES)
+			return 0;
+
+		desc = raw_cpu_ptr(gdt_page.gdt) + idx;
+	}
+
+	return get_desc_base(desc);
+}
+
+#ifdef CONFIG_IA32_EMULATION
+
+#include <asm/compat.h>
+
+static inline int
+perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
+{
+	/* 32-bit process in 64-bit kernel. */
+	unsigned long ss_base, cs_base;
+	struct stack_frame_ia32 frame;
+	const void __user *fp;
+
+	if (!test_thread_flag(TIF_IA32))
+		return 0;
+
+	cs_base = get_segment_base(regs->cs);
+	ss_base = get_segment_base(regs->ss);
+
+	fp = compat_ptr(ss_base + regs->bp);
+	pagefault_disable();
+	while (entry->nr < PERF_MAX_STACK_DEPTH) {
+		unsigned long bytes;
+		frame.next_frame     = 0;
+		frame.return_address = 0;
+
+		if (!access_ok(VERIFY_READ, fp, 8))
+			break;
+
+		bytes = __copy_from_user_nmi(&frame.next_frame, fp, 4);
+		if (bytes != 0)
+			break;
+		bytes = __copy_from_user_nmi(&frame.return_address, fp+4, 4);
+		if (bytes != 0)
+			break;
+
+		if (!valid_user_frame(fp, sizeof(frame)))
+			break;
+
+		perf_callchain_store(entry, cs_base + frame.return_address);
+		fp = compat_ptr(ss_base + frame.next_frame);
+	}
+	pagefault_enable();
+	return 1;
+}
+#else
+static inline int
+perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
+{
+    return 0;
+}
+#endif
+
+void
+perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
+{
+	struct stack_frame frame;
+	const void __user *fp;
+
+	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+		/* TODO: We don't support guest os callchain now */
+		return;
+	}
+
+	/*
+	 * We don't know what to do with VM86 stacks.. ignore them for now.
+	 */
+	if (regs->flags & (X86_VM_MASK | PERF_EFLAGS_VM))
+		return;
+
+	fp = (void __user *)regs->bp;
+
+	perf_callchain_store(entry, regs->ip);
+
+	if (!current->mm)
+		return;
+
+	if (perf_callchain_user32(regs, entry))
+		return;
+
+	pagefault_disable();
+	while (entry->nr < PERF_MAX_STACK_DEPTH) {
+		unsigned long bytes;
+		frame.next_frame	     = NULL;
+		frame.return_address = 0;
+
+		if (!access_ok(VERIFY_READ, fp, 16))
+			break;
+
+		bytes = __copy_from_user_nmi(&frame.next_frame, fp, 8);
+		if (bytes != 0)
+			break;
+		bytes = __copy_from_user_nmi(&frame.return_address, fp+8, 8);
+		if (bytes != 0)
+			break;
+
+		if (!valid_user_frame(fp, sizeof(frame)))
+			break;
+
+		perf_callchain_store(entry, frame.return_address);
+		fp = (void __user *)frame.next_frame;
+	}
+	pagefault_enable();
+}
+
+/*
+ * Deal with code segment offsets for the various execution modes:
+ *
+ *   VM86 - the good olde 16 bit days, where the linear address is
+ *          20 bits and we use regs->ip + 0x10 * regs->cs.
+ *
+ *   IA32 - Where we need to look at GDT/LDT segment descriptor tables
+ *          to figure out what the 32bit base address is.
+ *
+ *    X32 - has TIF_X32 set, but is running in x86_64
+ *
+ * X86_64 - CS,DS,SS,ES are all zero based.
+ */
+static unsigned long code_segment_base(struct pt_regs *regs)
+{
+	/*
+	 * For IA32 we look at the GDT/LDT segment base to convert the
+	 * effective IP to a linear address.
+	 */
+
+#ifdef CONFIG_X86_32
+	/*
+	 * If we are in VM86 mode, add the segment offset to convert to a
+	 * linear address.
+	 */
+	if (regs->flags & X86_VM_MASK)
+		return 0x10 * regs->cs;
+
+	if (user_mode(regs) && regs->cs != __USER_CS)
+		return get_segment_base(regs->cs);
+#else
+	if (user_mode(regs) && !user_64bit_mode(regs) &&
+	    regs->cs != __USER32_CS)
+		return get_segment_base(regs->cs);
+#endif
+	return 0;
+}
+
+unsigned long perf_instruction_pointer(struct pt_regs *regs)
+{
+	if (perf_guest_cbs && perf_guest_cbs->is_in_guest())
+		return perf_guest_cbs->get_guest_ip();
+
+	return regs->ip + code_segment_base(regs);
+}
+
+unsigned long perf_misc_flags(struct pt_regs *regs)
+{
+	int misc = 0;
+
+	if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
+		if (perf_guest_cbs->is_user_mode())
+			misc |= PERF_RECORD_MISC_GUEST_USER;
+		else
+			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
+	} else {
+		if (user_mode(regs))
+			misc |= PERF_RECORD_MISC_USER;
+		else
+			misc |= PERF_RECORD_MISC_KERNEL;
+	}
+
+	if (regs->flags & PERF_EFLAGS_EXACT)
+		misc |= PERF_RECORD_MISC_EXACT_IP;
+
+	return misc;
+}
+
+void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap)
+{
+	cap->version		= x86_pmu.version;
+	cap->num_counters_gp	= x86_pmu.num_counters;
+	cap->num_counters_fixed	= x86_pmu.num_counters_fixed;
+	cap->bit_width_gp	= x86_pmu.cntval_bits;
+	cap->bit_width_fixed	= x86_pmu.cntval_bits;
+	cap->events_mask	= (unsigned int)x86_pmu.events_maskl;
+	cap->events_mask_len	= x86_pmu.events_mask_len;
+}
+EXPORT_SYMBOL_GPL(perf_get_x86_pmu_capability);