/*
 * PMU support
 *
 * Copyright (C) 2012 ARM Limited
 * Author: Will Deacon <will.deacon@arm.com>
 *
 * This code is based heavily on the ARMv7 perf event code.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#define pr_fmt(fmt) "hw perfevents: " fmt

#include <linux/bitmap.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/perf_event.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>

#include <asm/cputype.h>
#include <asm/irq.h>
#include <asm/irq_regs.h>
#include <asm/pmu.h>
#include <asm/stacktrace.h>

/*
 * ARMv8 supports a maximum of 32 events.
 * The cycle counter is included in this total.
 */
#define ARMPMU_MAX_HWEVENTS             32

static DEFINE_PER_CPU(struct perf_event * [ARMPMU_MAX_HWEVENTS], hw_events);
static DEFINE_PER_CPU(unsigned long [BITS_TO_LONGS(ARMPMU_MAX_HWEVENTS)], used_mask);
static DEFINE_PER_CPU(struct pmu_hw_events, cpu_hw_events);

#define to_arm_pmu(p) (container_of(p, struct arm_pmu, pmu))

/* Set at runtime when we know what CPU type we are. */
static struct arm_pmu *cpu_pmu;

int
armpmu_get_max_events(void)
{
        int max_events = 0;

        if (cpu_pmu != NULL)
                max_events = cpu_pmu->num_events;

        return max_events;
}
EXPORT_SYMBOL_GPL(armpmu_get_max_events);

int perf_num_counters(void)
{
        return armpmu_get_max_events();
}
EXPORT_SYMBOL_GPL(perf_num_counters);

#define HW_OP_UNSUPPORTED               0xFFFF

#define C(_x) \
        PERF_COUNT_HW_CACHE_##_x

#define CACHE_OP_UNSUPPORTED            0xFFFF

static int
armpmu_map_cache_event(const unsigned (*cache_map)
                                      [PERF_COUNT_HW_CACHE_MAX]
                                      [PERF_COUNT_HW_CACHE_OP_MAX]
                                      [PERF_COUNT_HW_CACHE_RESULT_MAX],
                       u64 config)
{
        unsigned int cache_type, cache_op, cache_result, ret;

        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;

        ret = (int)(*cache_map)[cache_type][cache_op][cache_result];

        if (ret == CACHE_OP_UNSUPPORTED)
                return -ENOENT;

        return ret;
}

static int
armpmu_map_event(const unsigned (*event_map)[PERF_COUNT_HW_MAX], u64 config)
{
        int mapping;

        if (config >= PERF_COUNT_HW_MAX)
                return -EINVAL;

        mapping = (*event_map)[config];
        return mapping == HW_OP_UNSUPPORTED ? -ENOENT : mapping;
}

static int
armpmu_map_raw_event(u32 raw_event_mask, u64 config)
{
        return (int)(config & raw_event_mask);
}

static int map_cpu_event(struct perf_event *event,
                         const unsigned (*event_map)[PERF_COUNT_HW_MAX],
                         const unsigned (*cache_map)
                                        [PERF_COUNT_HW_CACHE_MAX]
                                        [PERF_COUNT_HW_CACHE_OP_MAX]
                                        [PERF_COUNT_HW_CACHE_RESULT_MAX],
                         u32 raw_event_mask)
{
        u64 config = event->attr.config;

        switch (event->attr.type) {
        case PERF_TYPE_HARDWARE:
                return armpmu_map_event(event_map, config);
        case PERF_TYPE_HW_CACHE:
                return armpmu_map_cache_event(cache_map, config);
        case PERF_TYPE_RAW:
                return armpmu_map_raw_event(raw_event_mask, config);
        }

        return -ENOENT;
}

int
armpmu_event_set_period(struct perf_event *event,
                        struct hw_perf_event *hwc,
                        int idx)
{
        struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
        s64 left = local64_read(&hwc->period_left);
        s64 period = hwc->sample_period;
        int ret = 0;

        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;
        }

        if (left > (s64)armpmu->max_period)
                left = armpmu->max_period;

        local64_set(&hwc->prev_count, (u64)-left);

        armpmu->write_counter(idx, (u64)(-left) & 0xffffffff);

        perf_event_update_userpage(event);

        return ret;
}

u64
armpmu_event_update(struct perf_event *event,
                    struct hw_perf_event *hwc,
                    int idx)
{
        struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
        u64 delta, prev_raw_count, new_raw_count;

again:
        prev_raw_count = local64_read(&hwc->prev_count);
        new_raw_count = armpmu->read_counter(idx);

        if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
                             new_raw_count) != prev_raw_count)
                goto again;

        delta = (new_raw_count - prev_raw_count) & armpmu->max_period;

        local64_add(delta, &event->count);
        local64_sub(delta, &hwc->period_left);

        return new_raw_count;
}

static void
armpmu_read(struct perf_event *event)
{
        struct hw_perf_event *hwc = &event->hw;

        /* Don't read disabled counters! */
        if (hwc->idx < 0)
                return;

        armpmu_event_update(event, hwc, hwc->idx);
}

static void
armpmu_stop(struct perf_event *event, int flags)
{
        struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
        struct hw_perf_event *hwc = &event->hw;

        /*
         * ARM pmu always has to update the counter, so ignore
         * PERF_EF_UPDATE, see comments in armpmu_start().
         */
        if (!(hwc->state & PERF_HES_STOPPED)) {
                armpmu->disable(hwc, hwc->idx);
                barrier(); /* why? */
                armpmu_event_update(event, hwc, hwc->idx);
                hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
        }
}

static void
armpmu_start(struct perf_event *event, int flags)
{
        struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
        struct hw_perf_event *hwc = &event->hw;

        /*
         * ARM pmu always has to reprogram the period, so ignore
         * PERF_EF_RELOAD, see the comment below.
         */
        if (flags & PERF_EF_RELOAD)
                WARN_ON_ONCE(!(hwc->state & PERF_HES_UPTODATE));

        hwc->state = 0;
        /*
         * Set the period again. Some counters can't be stopped, so when we
         * were stopped we simply disabled the IRQ source and the counter
         * may have been left counting. If we don't do this step then we may
         * get an interrupt too soon or *way* too late if the overflow has
         * happened since disabling.
         */
        armpmu_event_set_period(event, hwc, hwc->idx);
        armpmu->enable(hwc, hwc->idx);
}

static void
armpmu_del(struct perf_event *event, int flags)
{
        struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
        struct pmu_hw_events *hw_events = armpmu->get_hw_events();
        struct hw_perf_event *hwc = &event->hw;
        int idx = hwc->idx;

        WARN_ON(idx < 0);

        armpmu_stop(event, PERF_EF_UPDATE);
        hw_events->events[idx] = NULL;
        clear_bit(idx, hw_events->used_mask);

        perf_event_update_userpage(event);
}

static int
armpmu_add(struct perf_event *event, int flags)
{
        struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
        struct pmu_hw_events *hw_events = armpmu->get_hw_events();
        struct hw_perf_event *hwc = &event->hw;
        int idx;
        int err = 0;

        perf_pmu_disable(event->pmu);

        /* If we don't have a space for the counter then finish early. */
        idx = armpmu->get_event_idx(hw_events, hwc);
        if (idx < 0) {
                err = idx;
                goto out;
        }

        /*
         * If there is an event in the counter we are going to use then make
         * sure it is disabled.
         */
        event->hw.idx = idx;
        armpmu->disable(hwc, idx);
        hw_events->events[idx] = event;

        hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
        if (flags & PERF_EF_START)
                armpmu_start(event, PERF_EF_RELOAD);

        /* Propagate our changes to the userspace mapping. */
        perf_event_update_userpage(event);

out:
        perf_pmu_enable(event->pmu);
        return err;
}

static int
validate_event(struct pmu_hw_events *hw_events,
               struct perf_event *event)
{
        struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
        struct hw_perf_event fake_event = event->hw;
        struct pmu *leader_pmu = event->group_leader->pmu;

        if (is_software_event(event))
                return 1;

        if (event->pmu != leader_pmu || event->state < PERF_EVENT_STATE_OFF)
                return 1;

        if (event->state == PERF_EVENT_STATE_OFF && !event->attr.enable_on_exec)
                return 1;

        return armpmu->get_event_idx(hw_events, &fake_event) >= 0;
}

static int
validate_group(struct perf_event *event)
{
        struct perf_event *sibling, *leader = event->group_leader;
        struct pmu_hw_events fake_pmu;
        DECLARE_BITMAP(fake_used_mask, ARMPMU_MAX_HWEVENTS);

        /*
         * Initialise the fake PMU. We only need to populate the
         * used_mask for the purposes of validation.
         */
        memset(fake_used_mask, 0, sizeof(fake_used_mask));
        fake_pmu.used_mask = fake_used_mask;

        if (!validate_event(&fake_pmu, leader))
                return -EINVAL;

        list_for_each_entry(sibling, &leader->sibling_list, group_entry) {
                if (!validate_event(&fake_pmu, sibling))
                        return -EINVAL;
        }

        if (!validate_event(&fake_pmu, event))
                return -EINVAL;

        return 0;
}

static void
armpmu_disable_percpu_irq(void *data)
{
        unsigned int irq = *(unsigned int *)data;
        disable_percpu_irq(irq);
}

static void
armpmu_release_hardware(struct arm_pmu *armpmu)
{
        int irq;
        unsigned int i, irqs;
        struct platform_device *pmu_device = armpmu->plat_device;

        irqs = min(pmu_device->num_resources, num_possible_cpus());
        if (!irqs)
                return;

        irq = platform_get_irq(pmu_device, 0);
        if (irq <= 0)
                return;

        if (irq_is_percpu(irq)) {
                on_each_cpu(armpmu_disable_percpu_irq, &irq, 1);
                free_percpu_irq(irq, &cpu_hw_events);
        } else {
                for (i = 0; i < irqs; ++i) {
                        if (!cpumask_test_and_clear_cpu(i, &armpmu->active_irqs))
                                continue;
                        irq = platform_get_irq(pmu_device, i);
                        if (irq > 0)
                                free_irq(irq, armpmu);
                }
        }
}

static void
armpmu_enable_percpu_irq(void *data)
{
        unsigned int irq = *(unsigned int *)data;
        enable_percpu_irq(irq, IRQ_TYPE_NONE);
}

static int
armpmu_reserve_hardware(struct arm_pmu *armpmu)
{
        int err, irq;
        unsigned int i, irqs;
        struct platform_device *pmu_device = armpmu->plat_device;

        if (!pmu_device) {
                pr_err("no PMU device registered\n");
                return -ENODEV;
        }

        irqs = min(pmu_device->num_resources, num_possible_cpus());
        if (!irqs) {
                pr_err("no irqs for PMUs defined\n");
                return -ENODEV;
        }

        irq = platform_get_irq(pmu_device, 0);
        if (irq <= 0) {
                pr_err("failed to get valid irq for PMU device\n");
                return -ENODEV;
        }

        if (irq_is_percpu(irq)) {
                err = request_percpu_irq(irq, armpmu->handle_irq,
                                "arm-pmu", &cpu_hw_events);

                if (err) {
                        pr_err("unable to request percpu IRQ%d for ARM PMU counters\n",
                                        irq);
                        armpmu_release_hardware(armpmu);
                        return err;
                }

                on_each_cpu(armpmu_enable_percpu_irq, &irq, 1);
        } else {
                for (i = 0; i < irqs; ++i) {
                        err = 0;
                        irq = platform_get_irq(pmu_device, i);
                        if (irq <= 0)
                                continue;

                        /*
                         * If we have a single PMU interrupt that we can't shift,
                         * assume that we're running on a uniprocessor machine and
                         * continue. Otherwise, continue without this interrupt.
                         */
                        if (irq_set_affinity(irq, cpumask_of(i)) && irqs > 1) {
                                pr_warning("unable to set irq affinity (irq=%d, cpu=%u)\n",
                                                irq, i);
                                continue;
                        }

                        err = request_irq(irq, armpmu->handle_irq,
                                        IRQF_NOBALANCING,
                                        "arm-pmu", armpmu);
                        if (err) {
                                pr_err("unable to request IRQ%d for ARM PMU counters\n",
                                                irq);
                                armpmu_release_hardware(armpmu);
                                return err;
                        }

                        cpumask_set_cpu(i, &armpmu->active_irqs);
                }
        }

        return 0;
}

static void
hw_perf_event_destroy(struct perf_event *event)
{
        struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
        atomic_t *active_events  = &armpmu->active_events;
        struct mutex *pmu_reserve_mutex = &armpmu->reserve_mutex;

        if (atomic_dec_and_mutex_lock(active_events, pmu_reserve_mutex)) {
                armpmu_release_hardware(armpmu);
                mutex_unlock(pmu_reserve_mutex);
        }
}

static int
event_requires_mode_exclusion(struct perf_event_attr *attr)
{
        return attr->exclude_idle || attr->exclude_user ||
               attr->exclude_kernel || attr->exclude_hv;
}

static int
__hw_perf_event_init(struct perf_event *event)
{
        struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
        struct hw_perf_event *hwc = &event->hw;
        int mapping, err;

        mapping = armpmu->map_event(event);

        if (mapping < 0) {
                pr_debug("event %x:%llx not supported\n", event->attr.type,
                         event->attr.config);
                return mapping;
        }

        /*
         * We don't assign an index until we actually place the event onto
         * hardware. Use -1 to signify that we haven't decided where to put it
         * yet. For SMP systems, each core has it's own PMU so we can't do any
         * clever allocation or constraints checking at this point.
         */
        hwc->idx                = -1;
        hwc->config_base        = 0;
        hwc->config             = 0;
        hwc->event_base         = 0;

        /*
         * Check whether we need to exclude the counter from certain modes.
         */
        if ((!armpmu->set_event_filter ||
             armpmu->set_event_filter(hwc, &event->attr)) &&
             event_requires_mode_exclusion(&event->attr)) {
                pr_debug("ARM performance counters do not support mode exclusion\n");
                return -EPERM;
        }

        /*
         * Store the event encoding into the config_base field.
         */
        hwc->config_base            |= (unsigned long)mapping;

        if (!hwc->sample_period) {
                /*
                 * For non-sampling runs, limit the sample_period to half
                 * of the counter width. That way, the new counter value
                 * is far less likely to overtake the previous one unless
                 * you have some serious IRQ latency issues.
                 */
                hwc->sample_period  = armpmu->max_period >> 1;
                hwc->last_period    = hwc->sample_period;
                local64_set(&hwc->period_left, hwc->sample_period);
        }

        err = 0;
        if (event->group_leader != event) {
                err = validate_group(event);
                if (err)
                        return -EINVAL;
        }

        return err;
}

static int armpmu_event_init(struct perf_event *event)
{
        struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
        int err = 0;
        atomic_t *active_events = &armpmu->active_events;

        if (armpmu->map_event(event) == -ENOENT)
                return -ENOENT;

        event->destroy = hw_perf_event_destroy;

        if (!atomic_inc_not_zero(active_events)) {
                mutex_lock(&armpmu->reserve_mutex);
                if (atomic_read(active_events) == 0)
                        err = armpmu_reserve_hardware(armpmu);

                if (!err)
                        atomic_inc(active_events);
                mutex_unlock(&armpmu->reserve_mutex);
        }

        if (err)
                return err;

        err = __hw_perf_event_init(event);
        if (err)
                hw_perf_event_destroy(event);

        return err;
}

static void armpmu_enable(struct pmu *pmu)
{
        struct arm_pmu *armpmu = to_arm_pmu(pmu);
        struct pmu_hw_events *hw_events = armpmu->get_hw_events();
        int enabled = bitmap_weight(hw_events->used_mask, armpmu->num_events);

        if (enabled)
                armpmu->start();
}

static void armpmu_disable(struct pmu *pmu)
{
        struct arm_pmu *armpmu = to_arm_pmu(pmu);
        armpmu->stop();
}

static void __init armpmu_init(struct arm_pmu *armpmu)
{
        atomic_set(&armpmu->active_events, 0);
        mutex_init(&armpmu->reserve_mutex);

        armpmu->pmu = (struct pmu) {
                .pmu_enable     = armpmu_enable,
                .pmu_disable    = armpmu_disable,
                .event_init     = armpmu_event_init,
                .add            = armpmu_add,
                .del            = armpmu_del,
                .start          = armpmu_start,
                .stop           = armpmu_stop,
                .read           = armpmu_read,
        };
}

int __init armpmu_register(struct arm_pmu *armpmu, char *name, int type)
{
        armpmu_init(armpmu);
        return perf_pmu_register(&armpmu->pmu, name, type);
}

/*
 * ARMv8 PMUv3 Performance Events handling code.
 * Common event types.
 */
enum armv8_pmuv3_perf_types {
        /* Required events. */
        ARMV8_PMUV3_PERFCTR_PMNC_SW_INCR                        = 0x00,
        ARMV8_PMUV3_PERFCTR_L1_DCACHE_REFILL                    = 0x03,
        ARMV8_PMUV3_PERFCTR_L1_DCACHE_ACCESS                    = 0x04,
        ARMV8_PMUV3_PERFCTR_PC_BRANCH_MIS_PRED                  = 0x10,
        ARMV8_PMUV3_PERFCTR_CLOCK_CYCLES                        = 0x11,
        ARMV8_PMUV3_PERFCTR_PC_BRANCH_PRED                      = 0x12,

        /* At least one of the following is required. */
        ARMV8_PMUV3_PERFCTR_INSTR_EXECUTED                      = 0x08,
        ARMV8_PMUV3_PERFCTR_OP_SPEC                             = 0x1B,

        /* Common architectural events. */
        ARMV8_PMUV3_PERFCTR_MEM_READ                            = 0x06,
        ARMV8_PMUV3_PERFCTR_MEM_WRITE                           = 0x07,
        ARMV8_PMUV3_PERFCTR_EXC_TAKEN                           = 0x09,
        ARMV8_PMUV3_PERFCTR_EXC_EXECUTED                        = 0x0A,
        ARMV8_PMUV3_PERFCTR_CID_WRITE                           = 0x0B,
        ARMV8_PMUV3_PERFCTR_PC_WRITE                            = 0x0C,
        ARMV8_PMUV3_PERFCTR_PC_IMM_BRANCH                       = 0x0D,
        ARMV8_PMUV3_PERFCTR_PC_PROC_RETURN                      = 0x0E,
        ARMV8_PMUV3_PERFCTR_MEM_UNALIGNED_ACCESS                = 0x0F,
        ARMV8_PMUV3_PERFCTR_TTBR_WRITE                          = 0x1C,

        /* Common microarchitectural events. */
        ARMV8_PMUV3_PERFCTR_L1_ICACHE_REFILL                    = 0x01,
        ARMV8_PMUV3_PERFCTR_ITLB_REFILL                         = 0x02,
        ARMV8_PMUV3_PERFCTR_DTLB_REFILL                         = 0x05,
        ARMV8_PMUV3_PERFCTR_MEM_ACCESS                          = 0x13,
        ARMV8_PMUV3_PERFCTR_L1_ICACHE_ACCESS                    = 0x14,
        ARMV8_PMUV3_PERFCTR_L1_DCACHE_WB                        = 0x15,
        ARMV8_PMUV3_PERFCTR_L2_CACHE_ACCESS                     = 0x16,
        ARMV8_PMUV3_PERFCTR_L2_CACHE_REFILL                     = 0x17,
        ARMV8_PMUV3_PERFCTR_L2_CACHE_WB                         = 0x18,
        ARMV8_PMUV3_PERFCTR_BUS_ACCESS                          = 0x19,
        ARMV8_PMUV3_PERFCTR_MEM_ERROR                           = 0x1A,
        ARMV8_PMUV3_PERFCTR_BUS_CYCLES                          = 0x1D,
};

/* PMUv3 HW events mapping. */
static const unsigned armv8_pmuv3_perf_map[PERF_COUNT_HW_MAX] = {
        [PERF_COUNT_HW_CPU_CYCLES]              = ARMV8_PMUV3_PERFCTR_CLOCK_CYCLES,
        [PERF_COUNT_HW_INSTRUCTIONS]            = ARMV8_PMUV3_PERFCTR_INSTR_EXECUTED,
        [PERF_COUNT_HW_CACHE_REFERENCES]        = ARMV8_PMUV3_PERFCTR_L1_DCACHE_ACCESS,
        [PERF_COUNT_HW_CACHE_MISSES]            = ARMV8_PMUV3_PERFCTR_L1_DCACHE_REFILL,
        [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]     = HW_OP_UNSUPPORTED,
        [PERF_COUNT_HW_BRANCH_MISSES]           = ARMV8_PMUV3_PERFCTR_PC_BRANCH_MIS_PRED,
        [PERF_COUNT_HW_BUS_CYCLES]              = HW_OP_UNSUPPORTED,
        [PERF_COUNT_HW_STALLED_CYCLES_FRONTEND] = HW_OP_UNSUPPORTED,
        [PERF_COUNT_HW_STALLED_CYCLES_BACKEND]  = HW_OP_UNSUPPORTED,
};

static const unsigned armv8_pmuv3_perf_cache_map[PERF_COUNT_HW_CACHE_MAX]
                                                [PERF_COUNT_HW_CACHE_OP_MAX]
                                                [PERF_COUNT_HW_CACHE_RESULT_MAX] = {
        [C(L1D)] = {
                [C(OP_READ)] = {
                        [C(RESULT_ACCESS)]      = ARMV8_PMUV3_PERFCTR_L1_DCACHE_ACCESS,
                        [C(RESULT_MISS)]        = ARMV8_PMUV3_PERFCTR_L1_DCACHE_REFILL,
                },
                [C(OP_WRITE)] = {
                        [C(RESULT_ACCESS)]      = ARMV8_PMUV3_PERFCTR_L1_DCACHE_ACCESS,
                        [C(RESULT_MISS)]        = ARMV8_PMUV3_PERFCTR_L1_DCACHE_REFILL,
                },
                [C(OP_PREFETCH)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
        },
        [C(L1I)] = {
                [C(OP_READ)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
                [C(OP_WRITE)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
                [C(OP_PREFETCH)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
        },
        [C(LL)] = {
                [C(OP_READ)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
                [C(OP_WRITE)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
                [C(OP_PREFETCH)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
        },
        [C(DTLB)] = {
                [C(OP_READ)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
                [C(OP_WRITE)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
                [C(OP_PREFETCH)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
        },
        [C(ITLB)] = {
                [C(OP_READ)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
                [C(OP_WRITE)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
                [C(OP_PREFETCH)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
        },
        [C(BPU)] = {
                [C(OP_READ)] = {
                        [C(RESULT_ACCESS)]      = ARMV8_PMUV3_PERFCTR_PC_BRANCH_PRED,
                        [C(RESULT_MISS)]        = ARMV8_PMUV3_PERFCTR_PC_BRANCH_MIS_PRED,
                },
                [C(OP_WRITE)] = {
                        [C(RESULT_ACCESS)]      = ARMV8_PMUV3_PERFCTR_PC_BRANCH_PRED,
                        [C(RESULT_MISS)]        = ARMV8_PMUV3_PERFCTR_PC_BRANCH_MIS_PRED,
                },
                [C(OP_PREFETCH)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
        },
        [C(NODE)] = {
                [C(OP_READ)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
                [C(OP_WRITE)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
                [C(OP_PREFETCH)] = {
                        [C(RESULT_ACCESS)]      = CACHE_OP_UNSUPPORTED,
                        [C(RESULT_MISS)]        = CACHE_OP_UNSUPPORTED,
                },
        },
};

/*
 * Perf Events' indices
 */
#define ARMV8_IDX_CYCLE_COUNTER 0
#define ARMV8_IDX_COUNTER0      1
#define ARMV8_IDX_COUNTER_LAST  (ARMV8_IDX_CYCLE_COUNTER + cpu_pmu->num_events - 1)

#define ARMV8_MAX_COUNTERS      32
#define ARMV8_COUNTER_MASK      (ARMV8_MAX_COUNTERS - 1)

/*
 * ARMv8 low level PMU access
 */

/*
 * Perf Event to low level counters mapping
 */
#define ARMV8_IDX_TO_COUNTER(x) \
        (((x) - ARMV8_IDX_COUNTER0) & ARMV8_COUNTER_MASK)

/*
 * Per-CPU PMCR: config reg
 */
#define ARMV8_PMCR_E            (1 << 0) /* Enable all counters */
#define ARMV8_PMCR_P            (1 << 1) /* Reset all counters */
#define ARMV8_PMCR_C            (1 << 2) /* Cycle counter reset */
#define ARMV8_PMCR_D            (1 << 3) /* CCNT counts every 64th cpu cycle */
#define ARMV8_PMCR_X            (1 << 4) /* Export to ETM */
#define ARMV8_PMCR_DP           (1 << 5) /* Disable CCNT if non-invasive debug*/
#define ARMV8_PMCR_N_SHIFT      11       /* Number of counters supported */
#define ARMV8_PMCR_N_MASK       0x1f
#define ARMV8_PMCR_MASK         0x3f     /* Mask for writable bits */

/*
 * PMOVSR: counters overflow flag status reg
 */
#define ARMV8_OVSR_MASK         0xffffffff      /* Mask for writable bits */
#define ARMV8_OVERFLOWED_MASK   ARMV8_OVSR_MASK

/*
 * PMXEVTYPER: Event selection reg
 */
#define ARMV8_EVTYPE_MASK       0xc80003ff      /* Mask for writable bits */
#define ARMV8_EVTYPE_EVENT      0x3ff           /* Mask for EVENT bits */

/*
 * Event filters for PMUv3
 */
#define ARMV8_EXCLUDE_EL1       (1 << 31)
#define ARMV8_EXCLUDE_EL0       (1 << 30)
#define ARMV8_INCLUDE_EL2       (1 << 27)

static inline u32 armv8pmu_pmcr_read(void)
{
        u32 val;
        asm volatile("mrs %0, pmcr_el0" : "=r" (val));
        return val;
}

static inline void armv8pmu_pmcr_write(u32 val)
{
        val &= ARMV8_PMCR_MASK;
        isb();
        asm volatile("msr pmcr_el0, %0" :: "r" (val));
}

static inline int armv8pmu_has_overflowed(u32 pmovsr)
{
        return pmovsr & ARMV8_OVERFLOWED_MASK;
}

static inline int armv8pmu_counter_valid(int idx)
{
        return idx >= ARMV8_IDX_CYCLE_COUNTER && idx <= ARMV8_IDX_COUNTER_LAST;
}

static inline int armv8pmu_counter_has_overflowed(u32 pmnc, int idx)
{
        int ret = 0;
        u32 counter;

        if (!armv8pmu_counter_valid(idx)) {
                pr_err("CPU%u checking wrong counter %d overflow status\n",
                        smp_processor_id(), idx);
        } else {
                counter = ARMV8_IDX_TO_COUNTER(idx);
                ret = pmnc & BIT(counter);
        }

        return ret;
}

static inline int armv8pmu_select_counter(int idx)
{
        u32 counter;

        if (!armv8pmu_counter_valid(idx)) {
                pr_err("CPU%u selecting wrong PMNC counter %d\n",
                        smp_processor_id(), idx);
                return -EINVAL;
        }

        counter = ARMV8_IDX_TO_COUNTER(idx);
        asm volatile("msr pmselr_el0, %0" :: "r" (counter));
        isb();

        return idx;
}

static inline u32 armv8pmu_read_counter(int idx)
{
        u32 value = 0;

        if (!armv8pmu_counter_valid(idx))
                pr_err("CPU%u reading wrong counter %d\n",
                        smp_processor_id(), idx);
        else if (idx == ARMV8_IDX_CYCLE_COUNTER)
                asm volatile("mrs %0, pmccntr_el0" : "=r" (value));
        else if (armv8pmu_select_counter(idx) == idx)
                asm volatile("mrs %0, pmxevcntr_el0" : "=r" (value));

        return value;
}

static inline void armv8pmu_write_counter(int idx, u32 value)
{
        if (!armv8pmu_counter_valid(idx))
                pr_err("CPU%u writing wrong counter %d\n",
                        smp_processor_id(), idx);
        else if (idx == ARMV8_IDX_CYCLE_COUNTER)
                asm volatile("msr pmccntr_el0, %0" :: "r" (value));
        else if (armv8pmu_select_counter(idx) == idx)
                asm volatile("msr pmxevcntr_el0, %0" :: "r" (value));
}

static inline void armv8pmu_write_evtype(int idx, u32 val)
{
        if (armv8pmu_select_counter(idx) == idx) {
                val &= ARMV8_EVTYPE_MASK;
                asm volatile("msr pmxevtyper_el0, %0" :: "r" (val));
        }
}

static inline int armv8pmu_enable_counter(int idx)
{
        u32 counter;

        if (!armv8pmu_counter_valid(idx)) {
                pr_err("CPU%u enabling wrong PMNC counter %d\n",
                        smp_processor_id(), idx);
                return -EINVAL;
        }

        counter = ARMV8_IDX_TO_COUNTER(idx);
        asm volatile("msr pmcntenset_el0, %0" :: "r" (BIT(counter)));
        return idx;
}

static inline int armv8pmu_disable_counter(int idx)
{
        u32 counter;

        if (!armv8pmu_counter_valid(idx)) {
                pr_err("CPU%u disabling wrong PMNC counter %d\n",
                        smp_processor_id(), idx);
                return -EINVAL;
        }

        counter = ARMV8_IDX_TO_COUNTER(idx);
        asm volatile("msr pmcntenclr_el0, %0" :: "r" (BIT(counter)));
        return idx;
}

static inline int armv8pmu_enable_intens(int idx)
{
        u32 counter;

        if (!armv8pmu_counter_valid(idx)) {
                pr_err("CPU%u enabling wrong PMNC counter IRQ enable %d\n",
                        smp_processor_id(), idx);
                return -EINVAL;
        }

        counter = ARMV8_IDX_TO_COUNTER(idx);
        asm volatile("msr pmintenset_el1, %0" :: "r" (BIT(counter)));
        return idx;
}

static inline int armv8pmu_disable_intens(int idx)
{
        u32 counter;

        if (!armv8pmu_counter_valid(idx)) {
                pr_err("CPU%u disabling wrong PMNC counter IRQ enable %d\n",
                        smp_processor_id(), idx);
                return -EINVAL;
        }

        counter = ARMV8_IDX_TO_COUNTER(idx);
        asm volatile("msr pmintenclr_el1, %0" :: "r" (BIT(counter)));
        isb();
        /* Clear the overflow flag in case an interrupt is pending. */
        asm volatile("msr pmovsclr_el0, %0" :: "r" (BIT(counter)));
        isb();
        return idx;
}

static inline u32 armv8pmu_getreset_flags(void)

{
        u32 value;

        /* Read */
        asm volatile("mrs %0, pmovsclr_el0" : "=r" (value));

        /* Write to clear flags */
        value &= ARMV8_OVSR_MASK;
        asm volatile("msr pmovsclr_el0, %0" :: "r" (value));

        return value;
}

static void armv8pmu_enable_event(struct hw_perf_event *hwc, int idx)
{
        unsigned long flags;
        struct pmu_hw_events *events = cpu_pmu->get_hw_events();

        /*
         * Enable counter and interrupt, and set the counter to count
         * the event that we're interested in.
         */
        raw_spin_lock_irqsave(&events->pmu_lock, flags);

        /*
         * Disable counter
         */
        armv8pmu_disable_counter(idx);

        /*
         * Set event (if destined for PMNx counters).
         */
        armv8pmu_write_evtype(idx, hwc->config_base);

        /*
         * Enable interrupt for this counter
         */
        armv8pmu_enable_intens(idx);

        /*
         * Enable counter
         */
        armv8pmu_enable_counter(idx);

        raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
}

static void armv8pmu_disable_event(struct hw_perf_event *hwc, int idx)
{
        unsigned long flags;
        struct pmu_hw_events *events = cpu_pmu->get_hw_events();

        /*
         * Disable counter and interrupt
         */
        raw_spin_lock_irqsave(&events->pmu_lock, flags);

        /*
         * Disable counter
         */
        armv8pmu_disable_counter(idx);

        /*
         * Disable interrupt for this counter
         */
        armv8pmu_disable_intens(idx);

        raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
}

static irqreturn_t armv8pmu_handle_irq(int irq_num, void *dev)
{
        u32 pmovsr;
        struct perf_sample_data data;
        struct pmu_hw_events *cpuc;
        struct pt_regs *regs;
        int idx;

        /*
         * Get and reset the IRQ flags
         */
        pmovsr = armv8pmu_getreset_flags();

        /*
         * Did an overflow occur?
         */
        if (!armv8pmu_has_overflowed(pmovsr))
                return IRQ_NONE;

        /*
         * Handle the counter(s) overflow(s)
         */
        regs = get_irq_regs();

        cpuc = this_cpu_ptr(&cpu_hw_events);
        for (idx = 0; idx < cpu_pmu->num_events; ++idx) {
                struct perf_event *event = cpuc->events[idx];
                struct hw_perf_event *hwc;

                /* Ignore if we don't have an event. */
                if (!event)
                        continue;

                /*
                 * We have a single interrupt for all counters. Check that
                 * each counter has overflowed before we process it.
                 */
                if (!armv8pmu_counter_has_overflowed(pmovsr, idx))
                        continue;

                hwc = &event->hw;
                armpmu_event_update(event, hwc, idx);
                perf_sample_data_init(&data, 0, hwc->last_period);
                if (!armpmu_event_set_period(event, hwc, idx))
                        continue;

                if (perf_event_overflow(event, &data, regs))
                        cpu_pmu->disable(hwc, idx);
        }

        /*
         * Handle the pending perf events.
         *
         * Note: this call *must* be run with interrupts disabled. For
         * platforms that can have the PMU interrupts raised as an NMI, this
         * will not work.
         */
        irq_work_run();

        return IRQ_HANDLED;
}

static void armv8pmu_start(void)
{
        unsigned long flags;
        struct pmu_hw_events *events = cpu_pmu->get_hw_events();

        raw_spin_lock_irqsave(&events->pmu_lock, flags);
        /* Enable all counters */
        armv8pmu_pmcr_write(armv8pmu_pmcr_read() | ARMV8_PMCR_E);
        raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
}

static void armv8pmu_stop(void)
{
        unsigned long flags;
        struct pmu_hw_events *events = cpu_pmu->get_hw_events();

        raw_spin_lock_irqsave(&events->pmu_lock, flags);
        /* Disable all counters */
        armv8pmu_pmcr_write(armv8pmu_pmcr_read() & ~ARMV8_PMCR_E);
        raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
}

static int armv8pmu_get_event_idx(struct pmu_hw_events *cpuc,
                                  struct hw_perf_event *event)
{
        int idx;
        unsigned long evtype = event->config_base & ARMV8_EVTYPE_EVENT;

        /* Always place a cycle counter into the cycle counter. */
        if (evtype == ARMV8_PMUV3_PERFCTR_CLOCK_CYCLES) {
                if (test_and_set_bit(ARMV8_IDX_CYCLE_COUNTER, cpuc->used_mask))
                        return -EAGAIN;

                return ARMV8_IDX_CYCLE_COUNTER;
        }

        /*
         * For anything other than a cycle counter, try and use
         * the events counters
         */
        for (idx = ARMV8_IDX_COUNTER0; idx < cpu_pmu->num_events; ++idx) {
                if (!test_and_set_bit(idx, cpuc->used_mask))
                        return idx;
        }

        /* The counters are all in use. */
        return -EAGAIN;
}

/*
 * Add an event filter to a given event. This will only work for PMUv2 PMUs.
 */
static int armv8pmu_set_event_filter(struct hw_perf_event *event,
                                     struct perf_event_attr *attr)
{
        unsigned long config_base = 0;

        if (attr->exclude_idle)
                return -EPERM;
        if (attr->exclude_user)
                config_base |= ARMV8_EXCLUDE_EL0;
        if (attr->exclude_kernel)
                config_base |= ARMV8_EXCLUDE_EL1;
        if (!attr->exclude_hv)
                config_base |= ARMV8_INCLUDE_EL2;

        /*
         * Install the filter into config_base as this is used to
         * construct the event type.
         */
        event->config_base = config_base;

        return 0;
}

static void armv8pmu_reset(void *info)
{
        u32 idx, nb_cnt = cpu_pmu->num_events;

        /* The counter and interrupt enable registers are unknown at reset. */
        for (idx = ARMV8_IDX_CYCLE_COUNTER; idx < nb_cnt; ++idx)
                armv8pmu_disable_event(NULL, idx);

        /* Initialize & Reset PMNC: C and P bits. */
        armv8pmu_pmcr_write(ARMV8_PMCR_P | ARMV8_PMCR_C);

        /* Disable access from userspace. */
        asm volatile("msr pmuserenr_el0, %0" :: "r" (0));
}

static int armv8_pmuv3_map_event(struct perf_event *event)
{
        return map_cpu_event(event, &armv8_pmuv3_perf_map,
                                &armv8_pmuv3_perf_cache_map,
                                ARMV8_EVTYPE_EVENT);
}

static struct arm_pmu armv8pmu = {
        .handle_irq             = armv8pmu_handle_irq,
        .enable                 = armv8pmu_enable_event,
        .disable                = armv8pmu_disable_event,
        .read_counter           = armv8pmu_read_counter,
        .write_counter          = armv8pmu_write_counter,
        .get_event_idx          = armv8pmu_get_event_idx,
        .start                  = armv8pmu_start,
        .stop                   = armv8pmu_stop,
        .reset                  = armv8pmu_reset,
        .max_period             = (1LLU << 32) - 1,
};

static u32 __init armv8pmu_read_num_pmnc_events(void)
{
        u32 nb_cnt;

        /* Read the nb of CNTx counters supported from PMNC */
        nb_cnt = (armv8pmu_pmcr_read() >> ARMV8_PMCR_N_SHIFT) & ARMV8_PMCR_N_MASK;

        /* Add the CPU cycles counter and return */
        return nb_cnt + 1;
}

static struct arm_pmu *__init armv8_pmuv3_pmu_init(void)
{
        armv8pmu.name                   = "arm/armv8-pmuv3";
        armv8pmu.map_event              = armv8_pmuv3_map_event;
        armv8pmu.num_events             = armv8pmu_read_num_pmnc_events();
        armv8pmu.set_event_filter       = armv8pmu_set_event_filter;
        return &armv8pmu;
}

/*
 * Ensure the PMU has sane values out of reset.
 * This requires SMP to be available, so exists as a separate initcall.
 */
static int __init
cpu_pmu_reset(void)
{
        if (cpu_pmu && cpu_pmu->reset)
                return on_each_cpu(cpu_pmu->reset, NULL, 1);
        return 0;
}
arch_initcall(cpu_pmu_reset);

/*
 * PMU platform driver and devicetree bindings.
 */
static struct of_device_id armpmu_of_device_ids[] = {
        {.compatible = "arm,armv8-pmuv3"},
        {},
};

static int armpmu_device_probe(struct platform_device *pdev)
{
        if (!cpu_pmu)
                return -ENODEV;

        cpu_pmu->plat_device = pdev;
        return 0;
}

static struct platform_driver armpmu_driver = {
        .driver         = {
                .name   = "arm-pmu",
                .of_match_table = armpmu_of_device_ids,
        },
        .probe          = armpmu_device_probe,
};

static int __init register_pmu_driver(void)
{
        return platform_driver_register(&armpmu_driver);
}
device_initcall(register_pmu_driver);

static struct pmu_hw_events *armpmu_get_cpu_events(void)
{
        return this_cpu_ptr(&cpu_hw_events);
}

static void __init cpu_pmu_init(struct arm_pmu *armpmu)
{
        int cpu;
        for_each_possible_cpu(cpu) {
                struct pmu_hw_events *events = &per_cpu(cpu_hw_events, cpu);
                events->events = per_cpu(hw_events, cpu);
                events->used_mask = per_cpu(used_mask, cpu);
                raw_spin_lock_init(&events->pmu_lock);
        }
        armpmu->get_hw_events = armpmu_get_cpu_events;
}

static int __init init_hw_perf_events(void)
{
        u64 dfr = read_cpuid(ID_AA64DFR0_EL1);

        switch ((dfr >> 8) & 0xf) {
        case 0x1:       /* PMUv3 */
                cpu_pmu = armv8_pmuv3_pmu_init();
                break;
        }

        if (cpu_pmu) {
                pr_info("enabled with %s PMU driver, %d counters available\n",
                        cpu_pmu->name, cpu_pmu->num_events);
                cpu_pmu_init(cpu_pmu);
                armpmu_register(cpu_pmu, "cpu", PERF_TYPE_RAW);
        } else {
                pr_info("no hardware support available\n");
        }

        return 0;
}
early_initcall(init_hw_perf_events);

/*
 * Callchain handling code.
 */
struct frame_tail {
        struct frame_tail       __user *fp;
        unsigned long           lr;
} __attribute__((packed));

/*
 * Get the return address for a single stackframe and return a pointer to the
 * next frame tail.
 */
static struct frame_tail __user *
user_backtrace(struct frame_tail __user *tail,
               struct perf_callchain_entry *entry)
{
        struct frame_tail buftail;
        unsigned long err;

        /* Also check accessibility of one struct frame_tail beyond */
        if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
                return NULL;

        pagefault_disable();
        err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
        pagefault_enable();

        if (err)
                return NULL;

        perf_callchain_store(entry, buftail.lr);

        /*
         * Frame pointers should strictly progress back up the stack
         * (towards higher addresses).
         */
        if (tail >= buftail.fp)
                return NULL;

        return buftail.fp;
}

#ifdef CONFIG_COMPAT
/*
 * The registers we're interested in are at the end of the variable
 * length saved register structure. The fp points at the end of this
 * structure so the address of this struct is:
 * (struct compat_frame_tail *)(xxx->fp)-1
 *
 * This code has been adapted from the ARM OProfile support.
 */
struct compat_frame_tail {
        compat_uptr_t   fp; /* a (struct compat_frame_tail *) in compat mode */
        u32             sp;
        u32             lr;
} __attribute__((packed));

static struct compat_frame_tail __user *
compat_user_backtrace(struct compat_frame_tail __user *tail,
                      struct perf_callchain_entry *entry)
{
        struct compat_frame_tail buftail;
        unsigned long err;

        /* Also check accessibility of one struct frame_tail beyond */
        if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
                return NULL;

        pagefault_disable();
        err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
        pagefault_enable();

        if (err)
                return NULL;

        perf_callchain_store(entry, buftail.lr);

        /*
         * Frame pointers should strictly progress back up the stack
         * (towards higher addresses).
         */
        if (tail + 1 >= (struct compat_frame_tail __user *)
                        compat_ptr(buftail.fp))
                return NULL;

        return (struct compat_frame_tail __user *)compat_ptr(buftail.fp) - 1;
}
#endif /* CONFIG_COMPAT */

void perf_callchain_user(struct perf_callchain_entry *entry,
                         struct pt_regs *regs)
{
        if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
                /* We don't support guest os callchain now */
                return;
        }

        perf_callchain_store(entry, regs->pc);

        if (!compat_user_mode(regs)) {
                /* AARCH64 mode */
                struct frame_tail __user *tail;

                tail = (struct frame_tail __user *)regs->regs[29];

                while (entry->nr < PERF_MAX_STACK_DEPTH &&
                       tail && !((unsigned long)tail & 0xf))
                        tail = user_backtrace(tail, entry);
        } else {
#ifdef CONFIG_COMPAT
                /* AARCH32 compat mode */
                struct compat_frame_tail __user *tail;

                tail = (struct compat_frame_tail __user *)regs->compat_fp - 1;

                while ((entry->nr < PERF_MAX_STACK_DEPTH) &&
                        tail && !((unsigned long)tail & 0x3))
                        tail = compat_user_backtrace(tail, entry);
#endif
        }
}

/*
 * Gets called by walk_stackframe() for every stackframe. This will be called
 * whist unwinding the stackframe and is like a subroutine return so we use
 * the PC.
 */
static int callchain_trace(struct stackframe *frame, void *data)
{
        struct perf_callchain_entry *entry = data;
        perf_callchain_store(entry, frame->pc);
        return 0;
}

void perf_callchain_kernel(struct perf_callchain_entry *entry,
                           struct pt_regs *regs)
{
        struct stackframe frame;

        if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
                /* We don't support guest os callchain now */
                return;
        }

        frame.fp = regs->regs[29];
        frame.sp = regs->sp;
        frame.pc = regs->pc;

        walk_stackframe(&frame, callchain_trace, entry);
}

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 instruction_pointer(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;
        }

        return misc;
}