#undef DEBUG

/*
 * ARM performance counter support.
 *
 * Copyright (C) 2009 picoChip Designs, Ltd., Jamie Iles
 * Copyright (C) 2010 ARM Ltd., Will Deacon <will.deacon@arm.com>
 *
 * This code is based on the sparc64 perf event code, which is in turn based
 * on the x86 code. Callchain code is based on the ARM OProfile backtrace
 * code.
 */
#define pr_fmt(fmt) "hw perfevents: " fmt

#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/uaccess.h>
#include <linux/irq.h>
#include <linux/irqdesc.h>

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

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_hw_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);
}

int
armpmu_map_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_hw_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 arm_pmu *armpmu = to_arm_pmu(event->pmu);
        struct hw_perf_event *hwc = &event->hw;
        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(event, (u64)(-left) & 0xffffffff);

        perf_event_update_userpage(event);

        return ret;
}

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

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

        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)
{
        armpmu_event_update(event);
}

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(event);
                armpmu_event_update(event);
                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);
        armpmu->enable(event);
}

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;

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

        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, event);
        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(event);
        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);

        if (is_software_event(event))
                return 1;

        if (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, 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 irqreturn_t armpmu_dispatch_irq(int irq, void *dev)
{
        struct arm_pmu *armpmu;
        struct platform_device *plat_device;
        struct arm_pmu_platdata *plat;
        int ret;
        u64 start_clock, finish_clock;

        if (irq_is_percpu(irq))
                dev = *(void **)dev;
        armpmu = dev;
        plat_device = armpmu->plat_device;
        plat = dev_get_platdata(&plat_device->dev);

        start_clock = sched_clock();
        if (plat && plat->handle_irq)
                ret = plat->handle_irq(irq, dev, armpmu->handle_irq);
        else
                ret = armpmu->handle_irq(irq, dev);
        finish_clock = sched_clock();

        perf_sample_event_took(finish_clock - start_clock);
        return ret;
}

static void
armpmu_release_hardware(struct arm_pmu *armpmu)
{
        armpmu->free_irq(armpmu);
        pm_runtime_put_sync(&armpmu->plat_device->dev);
}

static int
armpmu_reserve_hardware(struct arm_pmu *armpmu)
{
        int err;
        struct platform_device *pmu_device = armpmu->plat_device;

        if (!pmu_device)
                return -ENODEV;

        pm_runtime_get_sync(&pmu_device->dev);
        err = armpmu->request_irq(armpmu, armpmu_dispatch_irq);
        if (err) {
                armpmu_release_hardware(armpmu);
                return err;
        }

        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;

        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 -EOPNOTSUPP;
        }

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

        if (!is_sampling_event(event)) {
                /*
                 * 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);
        }

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

        return 0;
}

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;

        /* does not support taken branch sampling */
        if (has_branch_stack(event))
                return -EOPNOTSUPP;

        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(armpmu);
}

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

#ifdef CONFIG_PM_RUNTIME
static int armpmu_runtime_resume(struct device *dev)
{
        struct arm_pmu_platdata *plat = dev_get_platdata(dev);

        if (plat && plat->runtime_resume)
                return plat->runtime_resume(dev);

        return 0;
}

static int armpmu_runtime_suspend(struct device *dev)
{
        struct arm_pmu_platdata *plat = dev_get_platdata(dev);

        if (plat && plat->runtime_suspend)
                return plat->runtime_suspend(dev);

        return 0;
}
#endif

const struct dev_pm_ops armpmu_dev_pm_ops = {
        SET_RUNTIME_PM_OPS(armpmu_runtime_suspend, armpmu_runtime_resume, NULL)
};

static void 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 armpmu_register(struct arm_pmu *armpmu, int type)
{
        armpmu_init(armpmu);
        pm_runtime_enable(&armpmu->plat_device->dev);
        pr_info("enabled with %s PMU driver, %d counters available\n",
                        armpmu->name, armpmu->num_events);
        return perf_pmu_register(&armpmu->pmu, armpmu->name, type);
}

/*
 * Callchain handling code.
 */

/*
 * 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 frame_tail *)(xxx->fp)-1
 *
 * This code has been adapted from the ARM OProfile support.
 */
struct frame_tail {
        struct frame_tail __user *fp;
        unsigned long sp;
        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;

        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 >= buftail.fp)
                return NULL;

        return buftail.fp - 1;
}

void
perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
{
        struct frame_tail __user *tail;

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

        perf_callchain_store(entry, regs->ARM_pc);

        if (!current->mm)
                return;

        tail = (struct frame_tail __user *)regs->ARM_fp - 1;

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

/*
 * 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 *fr,
                void *data)
{
        struct perf_callchain_entry *entry = data;
        perf_callchain_store(entry, fr->pc);
        return 0;
}

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

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

        arm_get_current_stackframe(regs, &fr);
        walk_stackframe(&fr, 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;
}