Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / arch / x86 / kernel / cpu / perf_event.c
diff --git a/kernel/arch/x86/kernel/cpu/perf_event.c b/kernel/arch/x86/kernel/cpu/perf_event.c
new file mode 100644 (file)
index 0000000..aa4e3a7
--- /dev/null
@@ -0,0 +1,2356 @@
+/*
+ * 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 <pzijlstr@redhat.com>
+ *  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 "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 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) {
+               printk(KERN_CONT "Broken BIOS detected, complain to your hardware vendor.\n");
+               printk(KERN_ERR FW_BUG "the BIOS has corrupted hw-PMU resources (MSR %x is %Lx)\n", reg_fail, val_fail);
+       }
+
+       return true;
+
+msr_fail:
+       printk(KERN_CONT "Broken PMU hardware detected, using software events only.\n");
+       printk("%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();
+}
+
+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(&active_events)) {
+               mutex_lock(&pmc_reserve_mutex);
+               if (atomic_read(&active_events) == 0) {
+                       if (!reserve_pmc_hardware())
+                               err = -EBUSY;
+                       else
+                               reserve_ds_buffers();
+               }
+               if (!err)
+                       atomic_inc(&active_events);
+               mutex_unlock(&pmc_reserve_mutex);
+       }
+
+       return err;
+}
+
+void x86_release_hardware(void)
+{
+       if (atomic_dec_and_mutex_lock(&active_events, &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 ret = -EBUSY, i;
+
+       if (atomic_inc_not_zero(&x86_pmu.lbr_exclusive[what]))
+               return 0;
+
+       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 out;
+       }
+
+       atomic_inc(&x86_pmu.lbr_exclusive[what]);
+       ret = 0;
+
+out:
+       mutex_unlock(&pmc_reserve_mutex);
+       return ret;
+}
+
+void x86_del_exclusive(unsigned int what)
+{
+       atomic_dec(&x86_pmu.lbr_exclusive[what]);
+}
+
+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 (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;
+
+       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]);
+               }
+       }
+
+       if (!assign || unsched) {
+
+               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;
+
+       /*
+        * 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->group_flag & PERF_EVENT_TXN)
+               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->group_flag & PERF_EVENT_TXN)
+               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;
+
+       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 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))
+                       continue;
+
+               for (j = i; attrs[j]; j++)
+                       attrs[j] = attrs[j + 1];
+
+               /* Check the shifted attr. */
+               i--;
+       }
+}
+
+/* Merge two pointer arrays */
+static __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
+ */
+static void x86_pmu_start_txn(struct pmu *pmu)
+{
+       perf_pmu_disable(pmu);
+       __this_cpu_or(cpu_hw_events.group_flag, PERF_EVENT_TXN);
+       __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)
+{
+       __this_cpu_and(cpu_hw_events.group_flag, ~PERF_EVENT_TXN);
+       /*
+        * 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;
+
+       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->group_flag &= ~PERF_EVENT_TXN;
+       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) {
+               if (idx > LDT_ENTRIES)
+                       return 0;
+
+               if (idx > current->active_mm->context.size)
+                       return 0;
+
+               desc = current->active_mm->context.ldt;
+       } else {
+               if (idx > GDT_ENTRIES)
+                       return 0;
+
+               desc = raw_cpu_ptr(gdt_page.gdt);
+       }
+
+       return get_desc_base(desc + idx);
+}
+
+#ifdef CONFIG_COMPAT
+
+#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);
+       while (entry->nr < PERF_MAX_STACK_DEPTH) {
+               unsigned long bytes;
+               frame.next_frame     = 0;
+               frame.return_address = 0;
+
+               bytes = copy_from_user_nmi(&frame, fp, sizeof(frame));
+               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);
+       }
+       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;
+
+       while (entry->nr < PERF_MAX_STACK_DEPTH) {
+               unsigned long bytes;
+               frame.next_frame             = NULL;
+               frame.return_address = 0;
+
+               bytes = copy_from_user_nmi(&frame, fp, sizeof(frame));
+               if (bytes != 0)
+                       break;
+
+               if (!valid_user_frame(fp, sizeof(frame)))
+                       break;
+
+               perf_callchain_store(entry, frame.return_address);
+               fp = frame.next_frame;
+       }
+}
+
+/*
+ * 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);