/*
 * 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/export.h>
#include <linux/init.h>
#include <linux/kdebug.h>
#include <linux/sched/mm.h>
#include <linux/sched/clock.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/cpu.h>
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/nospec.h>
#include <linux/static_call.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 <asm/unwind.h>

#include "perf_event.h"

struct x86_pmu x86_pmu __read_mostly;
static struct pmu pmu;

DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events) = {
        .enabled = 1,
        .pmu = &pmu,
};

DEFINE_STATIC_KEY_FALSE(rdpmc_never_available_key);
DEFINE_STATIC_KEY_FALSE(rdpmc_always_available_key);
DEFINE_STATIC_KEY_FALSE(perf_is_hybrid);

/*
 * This here uses DEFINE_STATIC_CALL_NULL() to get a static_call defined
 * from just a typename, as opposed to an actual function.
 */
DEFINE_STATIC_CALL_NULL(x86_pmu_handle_irq,  *x86_pmu.handle_irq);
DEFINE_STATIC_CALL_NULL(x86_pmu_disable_all, *x86_pmu.disable_all);
DEFINE_STATIC_CALL_NULL(x86_pmu_enable_all,  *x86_pmu.enable_all);
DEFINE_STATIC_CALL_NULL(x86_pmu_enable,      *x86_pmu.enable);
DEFINE_STATIC_CALL_NULL(x86_pmu_disable,     *x86_pmu.disable);

DEFINE_STATIC_CALL_NULL(x86_pmu_add,  *x86_pmu.add);
DEFINE_STATIC_CALL_NULL(x86_pmu_del,  *x86_pmu.del);
DEFINE_STATIC_CALL_NULL(x86_pmu_read, *x86_pmu.read);

DEFINE_STATIC_CALL_NULL(x86_pmu_schedule_events,       *x86_pmu.schedule_events);
DEFINE_STATIC_CALL_NULL(x86_pmu_get_event_constraints, *x86_pmu.get_event_constraints);
DEFINE_STATIC_CALL_NULL(x86_pmu_put_event_constraints, *x86_pmu.put_event_constraints);

DEFINE_STATIC_CALL_NULL(x86_pmu_start_scheduling,  *x86_pmu.start_scheduling);
DEFINE_STATIC_CALL_NULL(x86_pmu_commit_scheduling, *x86_pmu.commit_scheduling);
DEFINE_STATIC_CALL_NULL(x86_pmu_stop_scheduling,   *x86_pmu.stop_scheduling);

DEFINE_STATIC_CALL_NULL(x86_pmu_sched_task,    *x86_pmu.sched_task);
DEFINE_STATIC_CALL_NULL(x86_pmu_swap_task_ctx, *x86_pmu.swap_task_ctx);

DEFINE_STATIC_CALL_NULL(x86_pmu_drain_pebs,   *x86_pmu.drain_pebs);
DEFINE_STATIC_CALL_NULL(x86_pmu_pebs_aliases, *x86_pmu.pebs_aliases);

/*
 * This one is magic, it will get called even when PMU init fails (because
 * there is no PMU), in which case it should simply return NULL.
 */
DEFINE_STATIC_CALL_RET0(x86_pmu_guest_get_msrs, *x86_pmu.guest_get_msrs);

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;
        u64 delta;

        if (unlikely(!hwc->event_base))
                return 0;

        if (unlikely(is_topdown_count(event)) && x86_pmu.update_topdown_event)
                return x86_pmu.update_topdown_event(event);

        /*
         * 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 extra_reg *extra_regs = hybrid(event->pmu, extra_regs);
        struct hw_perf_event_extra *reg;
        struct extra_reg *er;

        reg = &event->hw.extra_reg;

        if (!extra_regs)
                return 0;

        for (er = 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 inline int get_possible_num_counters(void)
{
        int i, num_counters = x86_pmu.num_counters;

        if (!is_hybrid())
                return num_counters;

        for (i = 0; i < x86_pmu.num_hybrid_pmus; i++)
                num_counters = max_t(int, num_counters, x86_pmu.hybrid_pmu[i].num_counters);

        return num_counters;
}

static bool reserve_pmc_hardware(void)
{
        int i, num_counters = get_possible_num_counters();

        for (i = 0; i < num_counters; i++) {
                if (!reserve_perfctr_nmi(x86_pmu_event_addr(i)))
                        goto perfctr_fail;
        }

        for (i = 0; i < 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 = 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, num_counters = get_possible_num_counters();

        for (i = 0; i < 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

bool check_hw_exists(struct pmu *pmu, int num_counters, int num_counters_fixed)
{
        u64 val, val_fail = -1, val_new= ~0;
        int i, reg, reg_fail = -1, 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 < 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 (num_counters_fixed) {
                reg = MSR_ARCH_PERFMON_FIXED_CTR_CTRL;
                ret = rdmsrl_safe(reg, &val);
                if (ret)
                        goto msr_fail;
                for (i = 0; i < num_counters_fixed; i++) {
                        if (fixed_counter_disabled(i, pmu))
                                continue;
                        if (val & (0x03ULL << 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:
        if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
                pr_cont("PMU not available due to virtualization, using software events only.\n");
        } else {
                pr_cont("Broken PMU hardware detected, using software events only.\n");
                pr_err("Failed to access perfctr msr (MSR %x is %Lx)\n",
                       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_type = array_index_nospec(cache_type, PERF_COUNT_HW_CACHE_MAX);

        cache_op = (config >>  8) & 0xff;
        if (cache_op >= PERF_COUNT_HW_CACHE_OP_MAX)
                return -EINVAL;
        cache_op = array_index_nospec(cache_op, PERF_COUNT_HW_CACHE_OP_MAX);

        cache_result = (config >> 16) & 0xff;
        if (cache_result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
                return -EINVAL;
        cache_result = array_index_nospec(cache_result, PERF_COUNT_HW_CACHE_RESULT_MAX);

        val = hybrid_var(event->pmu, 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 = hybrid_var(event->pmu, 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();
                                reserve_lbr_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();
                release_lbr_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;

        /*
         * When lbr_pt_coexist we allow PT to coexist with either LBR or BTS.
         * LBR and BTS are still mutually exclusive.
         */
        if (x86_pmu.lbr_pt_coexist && what == x86_lbr_exclusive_pt)
                goto out;

        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);
        }

out:
        atomic_inc(&active_events);
        return 0;

fail_unlock:
        mutex_unlock(&pmc_reserve_mutex);
        return -EBUSY;
}

void x86_del_exclusive(unsigned int what)
{
        atomic_dec(&active_events);

        /*
         * See the comment in x86_add_exclusive().
         */
        if (x86_pmu.lbr_pt_coexist && what == x86_lbr_exclusive_pt)
                return;

        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 == event->pmu->type)
                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;

        attr->config = array_index_nospec((unsigned long)attr->config, x86_pmu.max_events);

        /*
         * The generic map:
         */
        config = x86_pmu.event_map(attr->config);

        if (config == 0)
                return -ENOENT;

        if (config == -1LL)
                return -EINVAL;

        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_max_precise(void)
{
        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++;
        }
        return precise;
}

int x86_pmu_hw_config(struct perf_event *event)
{
        if (event->attr.precise_ip) {
                int precise = x86_pmu_max_precise();

                if (event->attr.precise_ip > precise)
                        return -EOPNOTSUPP;

                /* There's no sense in having PEBS for non sampling events: */
                if (!is_sampling_event(event))
                        return -EINVAL;
        }
        /*
         * 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 == event->pmu->type)
                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;
        }

        /* sample_regs_user never support XMM registers */
        if (unlikely(event->attr.sample_regs_user & PERF_REG_EXTENDED_MASK))
                return -EINVAL;
        /*
         * Besides the general purpose registers, XMM registers may
         * be collected in PEBS on some platforms, e.g. Icelake
         */
        if (unlikely(event->attr.sample_regs_intr & PERF_REG_EXTENDED_MASK)) {
                if (!(event->pmu->capabilities & PERF_PMU_CAP_EXTENDED_REGS))
                        return -EINVAL;

                if (!event->attr.precise_ip)
                        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++) {
                struct hw_perf_event *hwc = &cpuc->events[idx]->hw;
                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);
                if (is_counter_pair(hwc))
                        wrmsrl(x86_pmu_config_addr(idx + 1), 0);
        }
}

struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr)
{
        return static_call(x86_pmu_guest_get_msrs)(nr);
}
EXPORT_SYMBOL_GPL(perf_guest_get_msrs);

/*
 * There may be PMI landing after enabled=0. The PMI hitting could be before or
 * after disable_all.
 *
 * If PMI hits before disable_all, the PMU will be disabled in the NMI handler.
 * It will not be re-enabled in the NMI handler again, because enabled=0. After
 * handling the NMI, disable_all will be called, which will not change the
 * state either. If PMI hits after disable_all, the PMU is already disabled
 * before entering NMI handler. The NMI handler will not change the state
 * either.
 *
 * So either situation is harmless.
 */
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();

        static_call(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 inline int is_x86_event(struct perf_event *event)
{
        int i;

        if (!is_hybrid())
                return event->pmu == &pmu;

        for (i = 0; i < x86_pmu.num_hybrid_pmus; i++) {
                if (event->pmu == &x86_pmu.hybrid_pmu[i].pmu)
                        return true;
        }

        return false;
}

struct pmu *x86_get_pmu(unsigned int cpu)
{
        struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);

        /*
         * All CPUs of the hybrid type have been offline.
         * The x86_get_pmu() should not be invoked.
         */
        if (WARN_ON_ONCE(!cpuc->pmu))
                return &pmu;

        return cpuc->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 */
        u64     used;
};

/* 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 iterator 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];

        /* this assignment didn't work out */
        /* XXX broken vs EVENT_PAIR */
        sched->state.used &= ~BIT_ULL(sched->state.counter);

        /* try the next one */
        sched->state.counter++;

        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) {
                        u64 mask = BIT_ULL(idx);

                        if (sched->state.used & mask)
                                continue;

                        sched->state.used |= mask;
                        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) {
                u64 mask = BIT_ULL(idx);

                if (c->flags & PERF_X86_EVENT_PAIR)
                        mask |= mask << 1;

                if (sched->state.used & mask)
                        continue;

                if (sched->state.nr_gp++ >= sched->max_gp)
                        return false;

                sched->state.used |= mask;
                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)
{
        int num_counters = hybrid(cpuc->pmu, num_counters);
        struct event_constraint *c;
        struct perf_event *e;
        int n0, i, wmin, wmax, unsched = 0;
        struct hw_perf_event *hwc;
        u64 used_mask = 0;

        /*
         * Compute the number of events already present; see x86_pmu_add(),
         * validate_group() and x86_pmu_commit_txn(). For the former two
         * cpuc->n_events hasn't been updated yet, while for the latter
         * cpuc->n_txn contains the number of events added in the current
         * transaction.
         */
        n0 = cpuc->n_events;
        if (cpuc->txn_flags & PERF_PMU_TXN_ADD)
                n0 -= cpuc->n_txn;

        static_call_cond(x86_pmu_start_scheduling)(cpuc);

        for (i = 0, wmin = X86_PMC_IDX_MAX, wmax = 0; i < n; i++) {
                c = cpuc->event_constraint[i];

                /*
                 * Previously scheduled events should have a cached constraint,
                 * while new events should not have one.
                 */

                WARN_ON_ONCE((c && i >= n0) || (!c && i < n0));

                /*
                 * Request constraints for new events; or for those events that
                 * have a dynamic constraint -- for those the constraint can
                 * change due to external factors (sibling state, allow_tfa).
                 */
                if (!c || (c->flags & PERF_X86_EVENT_DYNAMIC)) {
                        c = static_call(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++) {
                u64 mask;

                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;

                mask = BIT_ULL(hwc->idx);
                if (is_counter_pair(hwc))
                        mask |= mask << 1;

                /* not already used */
                if (used_mask & mask)
                        break;

                used_mask |= mask;

                if (assign)
                        assign[i] = hwc->idx;
        }

        /* slow path */
        if (i != n) {
                int gpmax = 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;

                /*
                 * Reduce the amount of available counters to allow fitting
                 * the extra Merge events needed by large increment events.
                 */
                if (x86_pmu.flags & PMU_FL_PAIR) {
                        gpmax = num_counters - cpuc->n_pair;
                        WARN_ON(gpmax <= 0);
                }

                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];
                        static_call_cond(x86_pmu_commit_scheduling)(cpuc, i, assign[i]);
                }
        } else {
                for (i = n0; i < n; i++) {
                        e = cpuc->event_list[i];

                        /*
                         * release events that failed scheduling
                         */
                        static_call_cond(x86_pmu_put_event_constraints)(cpuc, e);

                        cpuc->event_constraint[i] = NULL;
                }
        }

        static_call_cond(x86_pmu_stop_scheduling)(cpuc);

        return unsched ? -EINVAL : 0;
}

static int add_nr_metric_event(struct cpu_hw_events *cpuc,
                               struct perf_event *event)
{
        if (is_metric_event(event)) {
                if (cpuc->n_metric == INTEL_TD_METRIC_NUM)
                        return -EINVAL;
                cpuc->n_metric++;
                cpuc->n_txn_metric++;
        }

        return 0;
}

static void del_nr_metric_event(struct cpu_hw_events *cpuc,
                                struct perf_event *event)
{
        if (is_metric_event(event))
                cpuc->n_metric--;
}

static int collect_event(struct cpu_hw_events *cpuc, struct perf_event *event,
                         int max_count, int n)
{
        union perf_capabilities intel_cap = hybrid(cpuc->pmu, intel_cap);

        if (intel_cap.perf_metrics && add_nr_metric_event(cpuc, event))
                return -EINVAL;

        if (n >= max_count + cpuc->n_metric)
                return -EINVAL;

        cpuc->event_list[n] = event;
        if (is_counter_pair(&event->hw)) {
                cpuc->n_pair++;
                cpuc->n_txn_pair++;
        }

        return 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)
{
        int num_counters = hybrid(cpuc->pmu, num_counters);
        int num_counters_fixed = hybrid(cpuc->pmu, num_counters_fixed);
        struct perf_event *event;
        int n, max_count;

        max_count = num_counters + num_counters_fixed;

        /* current number of events already accepted */
        n = cpuc->n_events;
        if (!cpuc->n_events)
                cpuc->pebs_output = 0;

        if (!cpuc->is_fake && leader->attr.precise_ip) {
                /*
                 * For PEBS->PT, if !aux_event, the group leader (PT) went
                 * away, the group was broken down and this singleton event
                 * can't schedule any more.
                 */
                if (is_pebs_pt(leader) && !leader->aux_event)
                        return -EINVAL;

                /*
                 * pebs_output: 0: no PEBS so far, 1: PT, 2: DS
                 */
                if (cpuc->pebs_output &&
                    cpuc->pebs_output != is_pebs_pt(leader) + 1)
                        return -EINVAL;

                cpuc->pebs_output = is_pebs_pt(leader) + 1;
        }

        if (is_x86_event(leader)) {
                if (collect_event(cpuc, leader, max_count, n))
                        return -EINVAL;
                n++;
        }

        if (!dogrp)
                return n;

        for_each_sibling_event(event, leader) {
                if (!is_x86_event(event) || event->state <= PERF_EVENT_STATE_OFF)
                        continue;

                if (collect_event(cpuc, event, max_count, n))
                        return -EINVAL;

                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;
        int idx;

        idx = hwc->idx = cpuc->assign[i];
        hwc->last_cpu = smp_processor_id();
        hwc->last_tag = ++cpuc->tags[i];

        switch (hwc->idx) {
        case INTEL_PMC_IDX_FIXED_BTS:
        case INTEL_PMC_IDX_FIXED_VLBR:
                hwc->config_base = 0;
                hwc->event_base = 0;
                break;

        case INTEL_PMC_IDX_METRIC_BASE ... INTEL_PMC_IDX_METRIC_END:
                /* All the metric events are mapped onto the fixed counter 3. */
                idx = INTEL_PMC_IDX_FIXED_SLOTS;
                fallthrough;
        case INTEL_PMC_IDX_FIXED ... INTEL_PMC_IDX_FIXED_BTS-1:
                hwc->config_base = MSR_ARCH_PERFMON_FIXED_CTR_CTRL;
                hwc->event_base = MSR_ARCH_PERFMON_FIXED_CTR0 +
                                (idx - INTEL_PMC_IDX_FIXED);
                hwc->event_base_rdpmc = (idx - INTEL_PMC_IDX_FIXED) |
                                        INTEL_PMC_FIXED_RDPMC_BASE;
                break;

        default:
                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);
                break;
        }
}

/**
 * x86_perf_rdpmc_index - Return PMC counter used for event
 * @event: the perf_event to which the PMC counter was assigned
 *
 * The counter assigned to this performance event may change if interrupts
 * are enabled. This counter should thus never be used while interrupts are
 * enabled. Before this function is used to obtain the assigned counter the
 * event should be checked for validity using, for example,
 * perf_event_read_local(), within the same interrupt disabled section in
 * which this counter is planned to be used.
 *
 * Return: The index of the performance monitoring counter assigned to
 * @perf_event.
 */
int x86_perf_rdpmc_index(struct perf_event *event)
{
        lockdep_assert_irqs_disabled();

        return event->hw.event_base_rdpmc;
}

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();

        static_call(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 (unlikely(!hwc->event_base))
                return 0;

        if (unlikely(is_topdown_count(event)) &&
            x86_pmu.set_topdown_event_period)
                return x86_pmu.set_topdown_event_period(event);

        /*
         * 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);

        /*
         * Sign extend the Merge event counter's upper 16 bits since
         * we currently declare a 48-bit counter width
         */
        if (is_counter_pair(hwc))
                wrmsrl(x86_pmu_event_addr(idx + 1), 0xffff);

        /*
         * 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 scheduled 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 commit fails, we'll call ->del() on all events
         * for which ->add() was called.
         */
        if (cpuc->txn_flags & PERF_PMU_TXN_ADD)
                goto done_collect;

        ret = static_call(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;

        /*
         * This is before x86_pmu_enable() will call x86_pmu_start(),
         * so we enable LBRs before an event needs them etc..
         */
        static_call_cond(x86_pmu_add)(event);

        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);
        static_call(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;
        int cpu = smp_processor_id();
        struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
        int num_counters = hybrid(cpuc->pmu, num_counters);
        int num_counters_fixed = hybrid(cpuc->pmu, num_counters_fixed);
        struct event_constraint *pebs_constraints = hybrid(cpuc->pmu, pebs_constraints);
        unsigned long flags;
        int idx;

        if (!num_counters)
                return;

        local_irq_save(flags);

        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 (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 < 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 < num_counters_fixed; idx++) {
                if (fixed_counter_disabled(idx, cpuc->pmu))
                        continue;
                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_bit(hwc->idx, cpuc->active_mask)) {
                static_call(x86_pmu_disable)(event);
                __clear_bit(hwc->idx, cpuc->active_mask);
                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);
        union perf_capabilities intel_cap = hybrid(cpuc->pmu, intel_cap);
        int i;

        /*
         * If we're called during a txn, we only need to undo x86_pmu.add.
         * 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)
                goto do_del;

        __set_bit(event->hw.idx, cpuc->dirty);

        /*
         * 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;

        static_call_cond(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->event_constraint[i-1] = NULL;
        --cpuc->n_events;
        if (intel_cap.perf_metrics)
                del_nr_metric_event(cpuc, event);

        perf_event_update_userpage(event);

do_del:

        /*
         * This is after x86_pmu_stop(); so we disable LBRs after any
         * event can need them etc..
         */
        static_call_cond(x86_pmu_del)(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))
                        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 = static_call(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_prepare_cpu(unsigned int cpu)
{
        struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
        int i;

        for (i = 0 ; i < X86_PERF_KFREE_MAX; i++)
                cpuc->kfree_on_online[i] = NULL;
        if (x86_pmu.cpu_prepare)
                return x86_pmu.cpu_prepare(cpu);
        return 0;
}

static int x86_pmu_dead_cpu(unsigned int cpu)
{
        if (x86_pmu.cpu_dead)
                x86_pmu.cpu_dead(cpu);
        return 0;
}

static int x86_pmu_online_cpu(unsigned int cpu)
{
        struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
        int i;

        for (i = 0 ; i < X86_PERF_KFREE_MAX; i++) {
                kfree(cpuc->kfree_on_online[i]);
                cpuc->kfree_on_online[i] = NULL;
        }
        return 0;
}

static int x86_pmu_starting_cpu(unsigned int cpu)
{
        if (x86_pmu.cpu_starting)
                x86_pmu.cpu_starting(cpu);
        return 0;
}

static int x86_pmu_dying_cpu(unsigned int cpu)
{
        if (x86_pmu.cpu_dying)
                x86_pmu.cpu_dying(cpu);
        return 0;
}

static void __init pmu_check_apic(void)
{
        if (boot_cpu_has(X86_FEATURE_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 __ro_after_init = {
        .name = "format",
        .attrs = NULL,
};

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 = 0;

        if (pmu_attr->id < x86_pmu.max_events)
                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);
}
EXPORT_SYMBOL_GPL(events_sysfs_show);

ssize_t events_ht_sysfs_show(struct device *dev, struct device_attribute *attr,
                          char *page)
{
        struct perf_pmu_events_ht_attr *pmu_attr =
                container_of(attr, struct perf_pmu_events_ht_attr, attr);

        /*
         * Report conditional events depending on Hyper-Threading.
         *
         * This is overly conservative as usually the HT special
         * handling is not needed if the other CPU thread is idle.
         *
         * Note this does not (and cannot) handle the case when thread
         * siblings are invisible, for example with virtualization
         * if they are owned by some other guest.  The user tool
         * has to re-read when a thread sibling gets onlined later.
         */
        return sprintf(page, "%s",
                        topology_max_smt_threads() > 1 ?
                        pmu_attr->event_str_ht :
                        pmu_attr->event_str_noht);
}

ssize_t events_hybrid_sysfs_show(struct device *dev,
                                 struct device_attribute *attr,
                                 char *page)
{
        struct perf_pmu_events_hybrid_attr *pmu_attr =
                container_of(attr, struct perf_pmu_events_hybrid_attr, attr);
        struct x86_hybrid_pmu *pmu;
        const char *str, *next_str;
        int i;

        if (hweight64(pmu_attr->pmu_type) == 1)
                return sprintf(page, "%s", pmu_attr->event_str);

        /*
         * Hybrid PMUs may support the same event name, but with different
         * event encoding, e.g., the mem-loads event on an Atom PMU has
         * different event encoding from a Core PMU.
         *
         * The event_str includes all event encodings. Each event encoding
         * is divided by ";". The order of the event encodings must follow
         * the order of the hybrid PMU index.
         */
        pmu = container_of(dev_get_drvdata(dev), struct x86_hybrid_pmu, pmu);

        str = pmu_attr->event_str;
        for (i = 0; i < x86_pmu.num_hybrid_pmus; i++) {
                if (!(x86_pmu.hybrid_pmu[i].cpu_type & pmu_attr->pmu_type))
                        continue;
                if (x86_pmu.hybrid_pmu[i].cpu_type & pmu->cpu_type) {
                        next_str = strchr(str, ';');
                        if (next_str)
                                return snprintf(page, next_str - str + 1, "%s", str);
                        else
                                return sprintf(page, "%s", str);
                }
                str = strchr(str, ';');
                str++;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(events_hybrid_sysfs_show);

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,
};

/*
 * Remove all undefined events (x86_pmu.event_map(id) == 0)
 * out of events_attr attributes.
 */
static umode_t
is_visible(struct kobject *kobj, struct attribute *attr, int idx)
{
        struct perf_pmu_events_attr *pmu_attr;

        if (idx >= x86_pmu.max_events)
                return 0;

        pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr.attr);
        /* str trumps id */
        return pmu_attr->event_str || x86_pmu.event_map(idx) ? attr->mode : 0;
}

static struct attribute_group x86_pmu_events_group __ro_after_init = {
        .name = "events",
        .attrs = events_attr,
        .is_visible = is_visible,
};

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 struct attribute_group x86_pmu_attr_group;
static struct attribute_group x86_pmu_caps_group;