sparc64: Add perf callchain support.

[deliverable/linux.git] / arch / sparc / kernel / perf_event.c

/* Performance event support for sparc64.
 *
 * Copyright (C) 2009, 2010 David S. Miller <davem@davemloft.net>
 *
 * This code is based almost entirely upon the x86 perf event
 * code, which is:
 *
 *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
 *  Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
 *  Copyright (C) 2009 Jaswinder Singh Rajput
 *  Copyright (C) 2009 Advanced Micro Devices, Inc., Robert Richter
 *  Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
 */

#include <linux/perf_event.h>
#include <linux/kprobes.h>
#include <linux/kernel.h>
#include <linux/kdebug.h>
#include <linux/mutex.h>

#include <asm/stacktrace.h>
#include <asm/cpudata.h>
#include <asm/uaccess.h>
#include <asm/atomic.h>
#include <asm/nmi.h>
#include <asm/pcr.h>

#include "kstack.h"

/* Sparc64 chips have two performance counters, 32-bits each, with
 * overflow interrupts generated on transition from 0xffffffff to 0.
 * The counters are accessed in one go using a 64-bit register.
 *
 * Both counters are controlled using a single control register.  The
 * only way to stop all sampling is to clear all of the context (user,
 * supervisor, hypervisor) sampling enable bits.  But these bits apply
 * to both counters, thus the two counters can't be enabled/disabled
 * individually.
 *
 * The control register has two event fields, one for each of the two
 * counters.  It's thus nearly impossible to have one counter going
 * while keeping the other one stopped.  Therefore it is possible to
 * get overflow interrupts for counters not currently "in use" and
 * that condition must be checked in the overflow interrupt handler.
 *
 * So we use a hack, in that we program inactive counters with the
 * "sw_count0" and "sw_count1" events.  These count how many times
 * the instruction "sethi %hi(0xfc000), %g0" is executed.  It's an
 * unusual way to encode a NOP and therefore will not trigger in
 * normal code.
 */

#define MAX_HWEVENTS                    2
#define MAX_PERIOD                      ((1UL << 32) - 1)

#define PIC_UPPER_INDEX                 0
#define PIC_LOWER_INDEX                 1

struct cpu_hw_events {
        struct perf_event       *events[MAX_HWEVENTS];
        unsigned long           used_mask[BITS_TO_LONGS(MAX_HWEVENTS)];
        unsigned long           active_mask[BITS_TO_LONGS(MAX_HWEVENTS)];
        u64                     pcr;
        int                     enabled;
};
DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events) = { .enabled = 1, };

struct perf_event_map {
        u16     encoding;
        u8      pic_mask;
#define PIC_NONE        0x00
#define PIC_UPPER       0x01
#define PIC_LOWER       0x02
};

static unsigned long perf_event_encode(const struct perf_event_map *pmap)
{
        return ((unsigned long) pmap->encoding << 16) | pmap->pic_mask;
}

static void perf_event_decode(unsigned long val, u16 *enc, u8 *msk)
{
        *msk = val & 0xff;
        *enc = val >> 16;
}

#define C(x) PERF_COUNT_HW_CACHE_##x

#define CACHE_OP_UNSUPPORTED    0xfffe
#define CACHE_OP_NONSENSE       0xffff

typedef struct perf_event_map cache_map_t
                                [PERF_COUNT_HW_CACHE_MAX]
                                [PERF_COUNT_HW_CACHE_OP_MAX]
                                [PERF_COUNT_HW_CACHE_RESULT_MAX];

struct sparc_pmu {
        const struct perf_event_map     *(*event_map)(int);
        const cache_map_t               *cache_map;
        int                             max_events;
        int                             upper_shift;
        int                             lower_shift;
        int                             event_mask;
        int                             hv_bit;
        int                             irq_bit;
        int                             upper_nop;
        int                             lower_nop;
};

static const struct perf_event_map ultra3_perfmon_event_map[] = {
        [PERF_COUNT_HW_CPU_CYCLES] = { 0x0000, PIC_UPPER | PIC_LOWER },
        [PERF_COUNT_HW_INSTRUCTIONS] = { 0x0001, PIC_UPPER | PIC_LOWER },
        [PERF_COUNT_HW_CACHE_REFERENCES] = { 0x0009, PIC_LOWER },
        [PERF_COUNT_HW_CACHE_MISSES] = { 0x0009, PIC_UPPER },
};

static const struct perf_event_map *ultra3_event_map(int event_id)
{
        return &ultra3_perfmon_event_map[event_id];
}

static const cache_map_t ultra3_cache_map = {
[C(L1D)] = {
        [C(OP_READ)] = {
                [C(RESULT_ACCESS)] = { 0x09, PIC_LOWER, },
                [C(RESULT_MISS)] = { 0x09, PIC_UPPER, },
        },
        [C(OP_WRITE)] = {
                [C(RESULT_ACCESS)] = { 0x0a, PIC_LOWER },
                [C(RESULT_MISS)] = { 0x0a, PIC_UPPER },
        },
        [C(OP_PREFETCH)] = {
                [C(RESULT_ACCESS)] = { CACHE_OP_UNSUPPORTED },
                [C(RESULT_MISS)] = { CACHE_OP_UNSUPPORTED },
        },
},
[C(L1I)] = {
        [C(OP_READ)] = {
                [C(RESULT_ACCESS)] = { 0x09, PIC_LOWER, },
                [C(RESULT_MISS)] = { 0x09, PIC_UPPER, },
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = { CACHE_OP_NONSENSE },
                [ C(RESULT_MISS)   ] = { CACHE_OP_NONSENSE },
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = { CACHE_OP_UNSUPPORTED },
                [ C(RESULT_MISS)   ] = { CACHE_OP_UNSUPPORTED },
        },
},
[C(LL)] = {
        [C(OP_READ)] = {
                [C(RESULT_ACCESS)] = { 0x0c, PIC_LOWER, },
                [C(RESULT_MISS)] = { 0x0c, PIC_UPPER, },
        },
        [C(OP_WRITE)] = {
                [C(RESULT_ACCESS)] = { 0x0c, PIC_LOWER },
                [C(RESULT_MISS)] = { 0x0c, PIC_UPPER },
        },
        [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)] = { 0x12, PIC_UPPER, },
        },
        [ 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)] = { 0x11, PIC_UPPER, },
        },
        [ 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)] = { 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 },
        },
},
};

static const struct sparc_pmu ultra3_pmu = {
        .event_map      = ultra3_event_map,
        .cache_map      = &ultra3_cache_map,
        .max_events     = ARRAY_SIZE(ultra3_perfmon_event_map),
        .upper_shift    = 11,
        .lower_shift    = 4,
        .event_mask     = 0x3f,
        .upper_nop      = 0x1c,
        .lower_nop      = 0x14,
};

/* Niagara1 is very limited.  The upper PIC is hard-locked to count
 * only instructions, so it is free running which creates all kinds of
 * problems.  Some hardware designs make one wonder if the creator
 * even looked at how this stuff gets used by software.
 */
static const struct perf_event_map niagara1_perfmon_event_map[] = {
        [PERF_COUNT_HW_CPU_CYCLES] = { 0x00, PIC_UPPER },
        [PERF_COUNT_HW_INSTRUCTIONS] = { 0x00, PIC_UPPER },
        [PERF_COUNT_HW_CACHE_REFERENCES] = { 0, PIC_NONE },
        [PERF_COUNT_HW_CACHE_MISSES] = { 0x03, PIC_LOWER },
};

static const struct perf_event_map *niagara1_event_map(int event_id)
{
        return &niagara1_perfmon_event_map[event_id];
}

static const cache_map_t niagara1_cache_map = {
[C(L1D)] = {
        [C(OP_READ)] = {
                [C(RESULT_ACCESS)] = { CACHE_OP_UNSUPPORTED },
                [C(RESULT_MISS)] = { 0x03, PIC_LOWER, },
        },
        [C(OP_WRITE)] = {
                [C(RESULT_ACCESS)] = { CACHE_OP_UNSUPPORTED },
                [C(RESULT_MISS)] = { 0x03, PIC_LOWER, },
        },
        [C(OP_PREFETCH)] = {
                [C(RESULT_ACCESS)] = { CACHE_OP_UNSUPPORTED },
                [C(RESULT_MISS)] = { CACHE_OP_UNSUPPORTED },
        },
},
[C(L1I)] = {
        [C(OP_READ)] = {
                [C(RESULT_ACCESS)] = { 0x00, PIC_UPPER },
                [C(RESULT_MISS)] = { 0x02, PIC_LOWER, },
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = { CACHE_OP_NONSENSE },
                [ C(RESULT_MISS)   ] = { CACHE_OP_NONSENSE },
        },
        [ 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)] = { 0x07, PIC_LOWER, },
        },
        [C(OP_WRITE)] = {
                [C(RESULT_ACCESS)] = { CACHE_OP_UNSUPPORTED },
                [C(RESULT_MISS)] = { 0x07, PIC_LOWER, },
        },
        [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)] = { 0x05, PIC_LOWER, },
        },
        [ 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)] = { 0x04, PIC_LOWER, },
        },
        [ 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)] = { 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 },
        },
},
};

static const struct sparc_pmu niagara1_pmu = {
        .event_map      = niagara1_event_map,
        .cache_map      = &niagara1_cache_map,
        .max_events     = ARRAY_SIZE(niagara1_perfmon_event_map),
        .upper_shift    = 0,
        .lower_shift    = 4,
        .event_mask     = 0x7,
        .upper_nop      = 0x0,
        .lower_nop      = 0x0,
};

static const struct perf_event_map niagara2_perfmon_event_map[] = {
        [PERF_COUNT_HW_CPU_CYCLES] = { 0x02ff, PIC_UPPER | PIC_LOWER },
        [PERF_COUNT_HW_INSTRUCTIONS] = { 0x02ff, PIC_UPPER | PIC_LOWER },
        [PERF_COUNT_HW_CACHE_REFERENCES] = { 0x0208, PIC_UPPER | PIC_LOWER },
        [PERF_COUNT_HW_CACHE_MISSES] = { 0x0302, PIC_UPPER | PIC_LOWER },
        [PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = { 0x0201, PIC_UPPER | PIC_LOWER },
        [PERF_COUNT_HW_BRANCH_MISSES] = { 0x0202, PIC_UPPER | PIC_LOWER },
};

static const struct perf_event_map *niagara2_event_map(int event_id)
{
        return &niagara2_perfmon_event_map[event_id];
}

static const cache_map_t niagara2_cache_map = {
[C(L1D)] = {
        [C(OP_READ)] = {
                [C(RESULT_ACCESS)] = { 0x0208, PIC_UPPER | PIC_LOWER, },
                [C(RESULT_MISS)] = { 0x0302, PIC_UPPER | PIC_LOWER, },
        },
        [C(OP_WRITE)] = {
                [C(RESULT_ACCESS)] = { 0x0210, PIC_UPPER | PIC_LOWER, },
                [C(RESULT_MISS)] = { 0x0302, PIC_UPPER | PIC_LOWER, },
        },
        [C(OP_PREFETCH)] = {
                [C(RESULT_ACCESS)] = { CACHE_OP_UNSUPPORTED },
                [C(RESULT_MISS)] = { CACHE_OP_UNSUPPORTED },
        },
},
[C(L1I)] = {
        [C(OP_READ)] = {
                [C(RESULT_ACCESS)] = { 0x02ff, PIC_UPPER | PIC_LOWER, },
                [C(RESULT_MISS)] = { 0x0301, PIC_UPPER | PIC_LOWER, },
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = { CACHE_OP_NONSENSE },
                [ C(RESULT_MISS)   ] = { CACHE_OP_NONSENSE },
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = { CACHE_OP_UNSUPPORTED },
                [ C(RESULT_MISS)   ] = { CACHE_OP_UNSUPPORTED },
        },
},
[C(LL)] = {
        [C(OP_READ)] = {
                [C(RESULT_ACCESS)] = { 0x0208, PIC_UPPER | PIC_LOWER, },
                [C(RESULT_MISS)] = { 0x0330, PIC_UPPER | PIC_LOWER, },
        },
        [C(OP_WRITE)] = {
                [C(RESULT_ACCESS)] = { 0x0210, PIC_UPPER | PIC_LOWER, },
                [C(RESULT_MISS)] = { 0x0320, PIC_UPPER | PIC_LOWER, },
        },
        [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)] = { 0x0b08, PIC_UPPER | PIC_LOWER, },
        },
        [ 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)] = { 0xb04, PIC_UPPER | PIC_LOWER, },
        },
        [ 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)] = { 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 },
        },
},
};

static const struct sparc_pmu niagara2_pmu = {
        .event_map      = niagara2_event_map,
        .cache_map      = &niagara2_cache_map,
        .max_events     = ARRAY_SIZE(niagara2_perfmon_event_map),
        .upper_shift    = 19,
        .lower_shift    = 6,
        .event_mask     = 0xfff,
        .hv_bit         = 0x8,
        .irq_bit        = 0x30,
        .upper_nop      = 0x220,
        .lower_nop      = 0x220,
};

static const struct sparc_pmu *sparc_pmu __read_mostly;

static u64 event_encoding(u64 event_id, int idx)
{
        if (idx == PIC_UPPER_INDEX)
                event_id <<= sparc_pmu->upper_shift;
        else
                event_id <<= sparc_pmu->lower_shift;
        return event_id;
}

static u64 mask_for_index(int idx)
{
        return event_encoding(sparc_pmu->event_mask, idx);
}

static u64 nop_for_index(int idx)
{
        return event_encoding(idx == PIC_UPPER_INDEX ?
                              sparc_pmu->upper_nop :
                              sparc_pmu->lower_nop, idx);
}

static inline void sparc_pmu_enable_event(struct cpu_hw_events *cpuc, struct hw_perf_event *hwc, int idx)
{
        u64 val, mask = mask_for_index(idx);

        val = cpuc->pcr;
        val &= ~mask;
        val |= hwc->config;
        cpuc->pcr = val;

        pcr_ops->write(cpuc->pcr);
}

static inline void sparc_pmu_disable_event(struct cpu_hw_events *cpuc, struct hw_perf_event *hwc, int idx)
{
        u64 mask = mask_for_index(idx);
        u64 nop = nop_for_index(idx);
        u64 val;

        val = cpuc->pcr;
        val &= ~mask;
        val |= nop;
        cpuc->pcr = val;

        pcr_ops->write(cpuc->pcr);
}

void hw_perf_enable(void)
{
        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
        u64 val;
        int i;

        if (cpuc->enabled)
                return;

        cpuc->enabled = 1;
        barrier();

        val = cpuc->pcr;

        for (i = 0; i < MAX_HWEVENTS; i++) {
                struct perf_event *cp = cpuc->events[i];
                struct hw_perf_event *hwc;

                if (!cp)
                        continue;
                hwc = &cp->hw;
                val |= hwc->config_base;
        }

        cpuc->pcr = val;

        pcr_ops->write(cpuc->pcr);
}

void hw_perf_disable(void)
{
        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
        u64 val;

        if (!cpuc->enabled)
                return;

        cpuc->enabled = 0;

        val = cpuc->pcr;
        val &= ~(PCR_UTRACE | PCR_STRACE |
                 sparc_pmu->hv_bit | sparc_pmu->irq_bit);
        cpuc->pcr = val;

        pcr_ops->write(cpuc->pcr);
}

static u32 read_pmc(int idx)
{
        u64 val;

        read_pic(val);
        if (idx == PIC_UPPER_INDEX)
                val >>= 32;

        return val & 0xffffffff;
}

static void write_pmc(int idx, u64 val)
{
        u64 shift, mask, pic;

        shift = 0;
        if (idx == PIC_UPPER_INDEX)
                shift = 32;

        mask = ((u64) 0xffffffff) << shift;
        val <<= shift;

        read_pic(pic);
        pic &= ~mask;
        pic |= val;
        write_pic(pic);
}

static int sparc_perf_event_set_period(struct perf_event *event,
                                       struct hw_perf_event *hwc, int idx)
{
        s64 left = atomic64_read(&hwc->period_left);
        s64 period = hwc->sample_period;
        int ret = 0;

        if (unlikely(left <= -period)) {
                left = period;
                atomic64_set(&hwc->period_left, left);
                hwc->last_period = period;
                ret = 1;
        }

        if (unlikely(left <= 0)) {
                left += period;
                atomic64_set(&hwc->period_left, left);
                hwc->last_period = period;
                ret = 1;
        }
        if (left > MAX_PERIOD)
                left = MAX_PERIOD;

        atomic64_set(&hwc->prev_count, (u64)-left);

        write_pmc(idx, (u64)(-left) & 0xffffffff);

        perf_event_update_userpage(event);

        return ret;
}

static int sparc_pmu_enable(struct perf_event *event)
{
        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
        struct hw_perf_event *hwc = &event->hw;
        int idx = hwc->idx;

        if (test_and_set_bit(idx, cpuc->used_mask))
                return -EAGAIN;

        sparc_pmu_disable_event(cpuc, hwc, idx);

        cpuc->events[idx] = event;
        set_bit(idx, cpuc->active_mask);

        sparc_perf_event_set_period(event, hwc, idx);
        sparc_pmu_enable_event(cpuc, hwc, idx);
        perf_event_update_userpage(event);
        return 0;
}

static u64 sparc_perf_event_update(struct perf_event *event,
                                   struct hw_perf_event *hwc, int idx)
{
        int shift = 64 - 32;
        u64 prev_raw_count, new_raw_count;
        s64 delta;

again:
        prev_raw_count = atomic64_read(&hwc->prev_count);
        new_raw_count = read_pmc(idx);

        if (atomic64_cmpxchg(&hwc->prev_count, prev_raw_count,
                             new_raw_count) != prev_raw_count)
                goto again;

        delta = (new_raw_count << shift) - (prev_raw_count << shift);
        delta >>= shift;

        atomic64_add(delta, &event->count);
        atomic64_sub(delta, &hwc->period_left);

        return new_raw_count;
}

static void sparc_pmu_disable(struct perf_event *event)
{
        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
        struct hw_perf_event *hwc = &event->hw;
        int idx = hwc->idx;

        clear_bit(idx, cpuc->active_mask);
        sparc_pmu_disable_event(cpuc, hwc, idx);

        barrier();

        sparc_perf_event_update(event, hwc, idx);
        cpuc->events[idx] = NULL;
        clear_bit(idx, cpuc->used_mask);

        perf_event_update_userpage(event);
}

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

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

static void sparc_pmu_unthrottle(struct perf_event *event)
{
        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
        struct hw_perf_event *hwc = &event->hw;

        sparc_pmu_enable_event(cpuc, hwc, hwc->idx);
}

static atomic_t active_events = ATOMIC_INIT(0);
static DEFINE_MUTEX(pmc_grab_mutex);

static void perf_stop_nmi_watchdog(void *unused)
{
        struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);

        stop_nmi_watchdog(NULL);
        cpuc->pcr = pcr_ops->read();
}

void perf_event_grab_pmc(void)
{
        if (atomic_inc_not_zero(&active_events))
                return;

        mutex_lock(&pmc_grab_mutex);
        if (atomic_read(&active_events) == 0) {
                if (atomic_read(&nmi_active) > 0) {
                        on_each_cpu(perf_stop_nmi_watchdog, NULL, 1);
                        BUG_ON(atomic_read(&nmi_active) != 0);
                }
                atomic_inc(&active_events);
        }
        mutex_unlock(&pmc_grab_mutex);
}

void perf_event_release_pmc(void)
{
        if (atomic_dec_and_mutex_lock(&active_events, &pmc_grab_mutex)) {
                if (atomic_read(&nmi_active) == 0)
                        on_each_cpu(start_nmi_watchdog, NULL, 1);
                mutex_unlock(&pmc_grab_mutex);
        }
}

static const struct perf_event_map *sparc_map_cache_event(u64 config)
{
        unsigned int cache_type, cache_op, cache_result;
        const struct perf_event_map *pmap;

        if (!sparc_pmu->cache_map)
                return ERR_PTR(-ENOENT);

        cache_type = (config >>  0) & 0xff;
        if (cache_type >= PERF_COUNT_HW_CACHE_MAX)
                return ERR_PTR(-EINVAL);

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

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

        pmap = &((*sparc_pmu->cache_map)[cache_type][cache_op][cache_result]);

        if (pmap->encoding == CACHE_OP_UNSUPPORTED)
                return ERR_PTR(-ENOENT);

        if (pmap->encoding == CACHE_OP_NONSENSE)
                return ERR_PTR(-EINVAL);

        return pmap;
}

static void hw_perf_event_destroy(struct perf_event *event)
{
        perf_event_release_pmc();
}

/* Make sure all events can be scheduled into the hardware at
 * the same time.  This is simplified by the fact that we only
 * need to support 2 simultaneous HW events.
 */
static int sparc_check_constraints(unsigned long *events, int n_ev)
{
        if (n_ev <= perf_max_events) {
                u8 msk1, msk2;
                u16 dummy;

                if (n_ev == 1)
                        return 0;
                BUG_ON(n_ev != 2);
                perf_event_decode(events[0], &dummy, &msk1);
                perf_event_decode(events[1], &dummy, &msk2);

                /* If both events can go on any counter, OK.  */
                if (msk1 == (PIC_UPPER | PIC_LOWER) &&
                    msk2 == (PIC_UPPER | PIC_LOWER))
                        return 0;

                /* If one event is limited to a specific counter,
                 * and the other can go on both, OK.
                 */
                if ((msk1 == PIC_UPPER || msk1 == PIC_LOWER) &&
                    msk2 == (PIC_UPPER | PIC_LOWER))
                        return 0;
                if ((msk2 == PIC_UPPER || msk2 == PIC_LOWER) &&
                    msk1 == (PIC_UPPER | PIC_LOWER))
                        return 0;

                /* If the events are fixed to different counters, OK.  */
                if ((msk1 == PIC_UPPER && msk2 == PIC_LOWER) ||
                    (msk1 == PIC_LOWER && msk2 == PIC_UPPER))
                        return 0;

                /* Otherwise, there is a conflict.  */
        }

        return -1;
}

static int check_excludes(struct perf_event **evts, int n_prev, int n_new)
{
        int eu = 0, ek = 0, eh = 0;
        struct perf_event *event;
        int i, n, first;

        n = n_prev + n_new;
        if (n <= 1)
                return 0;

        first = 1;
        for (i = 0; i < n; i++) {
                event = evts[i];
                if (first) {
                        eu = event->attr.exclude_user;
                        ek = event->attr.exclude_kernel;
                        eh = event->attr.exclude_hv;
                        first = 0;
                } else if (event->attr.exclude_user != eu ||
                           event->attr.exclude_kernel != ek ||
                           event->attr.exclude_hv != eh) {
                        return -EAGAIN;
                }
        }

        return 0;
}

static int collect_events(struct perf_event *group, int max_count,
                          struct perf_event *evts[], unsigned long *events)
{
        struct perf_event *event;
        int n = 0;

        if (!is_software_event(group)) {
                if (n >= max_count)
                        return -1;
                evts[n] = group;
                events[n++] = group->hw.event_base;
        }
        list_for_each_entry(event, &group->sibling_list, group_entry) {
                if (!is_software_event(event) &&
                    event->state != PERF_EVENT_STATE_OFF) {
                        if (n >= max_count)
                                return -1;
                        evts[n] = event;
                        events[n++] = event->hw.event_base;
                }
        }
        return n;
}

static int __hw_perf_event_init(struct perf_event *event)
{
        struct perf_event_attr *attr = &event->attr;
        struct perf_event *evts[MAX_HWEVENTS];
        struct hw_perf_event *hwc = &event->hw;
        unsigned long events[MAX_HWEVENTS];
        const struct perf_event_map *pmap;
        u64 enc;
        int n;

        if (atomic_read(&nmi_active) < 0)
                return -ENODEV;

        if (attr->type == PERF_TYPE_HARDWARE) {
                if (attr->config >= sparc_pmu->max_events)
                        return -EINVAL;
                pmap = sparc_pmu->event_map(attr->config);
        } else if (attr->type == PERF_TYPE_HW_CACHE) {
                pmap = sparc_map_cache_event(attr->config);
                if (IS_ERR(pmap))
                        return PTR_ERR(pmap);
        } else
                return -EOPNOTSUPP;

        /* We save the enable bits in the config_base.  So to
         * turn off sampling just write 'config', and to enable
         * things write 'config | config_base'.
         */
        hwc->config_base = sparc_pmu->irq_bit;
        if (!attr->exclude_user)
                hwc->config_base |= PCR_UTRACE;
        if (!attr->exclude_kernel)
                hwc->config_base |= PCR_STRACE;
        if (!attr->exclude_hv)
                hwc->config_base |= sparc_pmu->hv_bit;

        hwc->event_base = perf_event_encode(pmap);

        enc = pmap->encoding;

        n = 0;
        if (event->group_leader != event) {
                n = collect_events(event->group_leader,
                                   perf_max_events - 1,
                                   evts, events);
                if (n < 0)
                        return -EINVAL;
        }
        events[n] = hwc->event_base;
        evts[n] = event;

        if (check_excludes(evts, n, 1))
                return -EINVAL;

        if (sparc_check_constraints(events, n + 1))
                return -EINVAL;

        /* Try to do all error checking before this point, as unwinding
         * state after grabbing the PMC is difficult.
         */
        perf_event_grab_pmc();
        event->destroy = hw_perf_event_destroy;

        if (!hwc->sample_period) {
                hwc->sample_period = MAX_PERIOD;
                hwc->last_period = hwc->sample_period;
                atomic64_set(&hwc->period_left, hwc->sample_period);
        }

        if (pmap->pic_mask & PIC_UPPER) {
                hwc->idx = PIC_UPPER_INDEX;
                enc <<= sparc_pmu->upper_shift;
        } else {
                hwc->idx = PIC_LOWER_INDEX;
                enc <<= sparc_pmu->lower_shift;
        }

        hwc->config |= enc;
        return 0;
}

static const struct pmu pmu = {
        .enable         = sparc_pmu_enable,
        .disable        = sparc_pmu_disable,
        .read           = sparc_pmu_read,
        .unthrottle     = sparc_pmu_unthrottle,
};

const struct pmu *hw_perf_event_init(struct perf_event *event)
{
        int err = __hw_perf_event_init(event);

        if (err)
                return ERR_PTR(err);
        return &pmu;
}

void perf_event_print_debug(void)
{
        unsigned long flags;
        u64 pcr, pic;
        int cpu;

        if (!sparc_pmu)
                return;

        local_irq_save(flags);

        cpu = smp_processor_id();

        pcr = pcr_ops->read();
        read_pic(pic);

        pr_info("\n");
        pr_info("CPU#%d: PCR[%016llx] PIC[%016llx]\n",
                cpu, pcr, pic);

        local_irq_restore(flags);
}

static int __kprobes perf_event_nmi_handler(struct notifier_block *self,
                                            unsigned long cmd, void *__args)
{
        struct die_args *args = __args;
        struct perf_sample_data data;
        struct cpu_hw_events *cpuc;
        struct pt_regs *regs;
        int idx;

        if (!atomic_read(&active_events))
                return NOTIFY_DONE;

        switch (cmd) {
        case DIE_NMI:
                break;

        default:
                return NOTIFY_DONE;
        }

        regs = args->regs;

        data.addr = 0;

        cpuc = &__get_cpu_var(cpu_hw_events);

        /* If the PMU has the TOE IRQ enable bits, we need to do a
         * dummy write to the %pcr to clear the overflow bits and thus
         * the interrupt.
         *
         * Do this before we peek at the counters to determine
         * overflow so we don't lose any events.
         */
        if (sparc_pmu->irq_bit)
                pcr_ops->write(cpuc->pcr);

        for (idx = 0; idx < MAX_HWEVENTS; idx++) {
                struct perf_event *event = cpuc->events[idx];
                struct hw_perf_event *hwc;
                u64 val;

                if (!test_bit(idx, cpuc->active_mask))
                        continue;
                hwc = &event->hw;
                val = sparc_perf_event_update(event, hwc, idx);
                if (val & (1ULL << 31))
                        continue;

                data.period = event->hw.last_period;
                if (!sparc_perf_event_set_period(event, hwc, idx))
                        continue;

                if (perf_event_overflow(event, 1, &data, regs))
                        sparc_pmu_disable_event(cpuc, hwc, idx);
        }

        return NOTIFY_STOP;
}

static __read_mostly struct notifier_block perf_event_nmi_notifier = {
        .notifier_call          = perf_event_nmi_handler,
};

static bool __init supported_pmu(void)
{
        if (!strcmp(sparc_pmu_type, "ultra3") ||
            !strcmp(sparc_pmu_type, "ultra3+") ||
            !strcmp(sparc_pmu_type, "ultra3i") ||
            !strcmp(sparc_pmu_type, "ultra4+")) {
                sparc_pmu = &ultra3_pmu;
                return true;
        }
        if (!strcmp(sparc_pmu_type, "niagara")) {
                sparc_pmu = &niagara1_pmu;
                return true;
        }
        if (!strcmp(sparc_pmu_type, "niagara2")) {
                sparc_pmu = &niagara2_pmu;
                return true;
        }
        return false;
}

void __init init_hw_perf_events(void)
{
        pr_info("Performance events: ");

        if (!supported_pmu()) {
                pr_cont("No support for PMU type '%s'\n", sparc_pmu_type);
                return;
        }

        pr_cont("Supported PMU type is '%s'\n", sparc_pmu_type);

        /* All sparc64 PMUs currently have 2 events.  But this simple
         * driver only supports one active event at a time.
         */
        perf_max_events = 1;

        register_die_notifier(&perf_event_nmi_notifier);
}

static inline void callchain_store(struct perf_callchain_entry *entry, u64 ip)
{
        if (entry->nr < PERF_MAX_STACK_DEPTH)
                entry->ip[entry->nr++] = ip;
}

static void perf_callchain_kernel(struct pt_regs *regs,
                                  struct perf_callchain_entry *entry)
{
        unsigned long ksp, fp;

        callchain_store(entry, PERF_CONTEXT_KERNEL);
        callchain_store(entry, regs->tpc);

        ksp = regs->u_regs[UREG_I6];
        fp = ksp + STACK_BIAS;
        do {
                struct sparc_stackf *sf;
                struct pt_regs *regs;
                unsigned long pc;

                if (!kstack_valid(current_thread_info(), fp))
                        break;

                sf = (struct sparc_stackf *) fp;
                regs = (struct pt_regs *) (sf + 1);

                if (kstack_is_trap_frame(current_thread_info(), regs)) {
                        if (user_mode(regs))
                                break;
                        pc = regs->tpc;
                        fp = regs->u_regs[UREG_I6] + STACK_BIAS;
                } else {
                        pc = sf->callers_pc;
                        fp = (unsigned long)sf->fp + STACK_BIAS;
                }
                callchain_store(entry, pc);
        } while (entry->nr < PERF_MAX_STACK_DEPTH);
}

static void perf_callchain_user_64(struct pt_regs *regs,
                                   struct perf_callchain_entry *entry)
{
        unsigned long ufp;

        callchain_store(entry, PERF_CONTEXT_USER);
        callchain_store(entry, regs->tpc);

        ufp = regs->u_regs[UREG_I6] + STACK_BIAS;
        do {
                struct sparc_stackf *usf, sf;
                unsigned long pc;

                usf = (struct sparc_stackf *) ufp;
                if (__copy_from_user_inatomic(&sf, usf, sizeof(sf)))
                        break;

                pc = sf.callers_pc;
                ufp = (unsigned long)sf.fp + STACK_BIAS;
                callchain_store(entry, pc);
        } while (entry->nr < PERF_MAX_STACK_DEPTH);
}

static void perf_callchain_user_32(struct pt_regs *regs,
                                   struct perf_callchain_entry *entry)
{
        unsigned long ufp;

        callchain_store(entry, PERF_CONTEXT_USER);
        callchain_store(entry, regs->tpc);

        ufp = regs->u_regs[UREG_I6];
        do {
                struct sparc_stackf32 *usf, sf;
                unsigned long pc;

                usf = (struct sparc_stackf32 *) ufp;
                if (__copy_from_user_inatomic(&sf, usf, sizeof(sf)))
                        break;

                pc = sf.callers_pc;
                ufp = (unsigned long)sf.fp;
                callchain_store(entry, pc);
        } while (entry->nr < PERF_MAX_STACK_DEPTH);
}

/* Like powerpc we can't get PMU interrupts within the PMU handler,
 * so no need for seperate NMI and IRQ chains as on x86.
 */
static DEFINE_PER_CPU(struct perf_callchain_entry, callchain);

struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
{
        struct perf_callchain_entry *entry = &__get_cpu_var(callchain);

        entry->nr = 0;
        if (!user_mode(regs)) {
                stack_trace_flush();
                perf_callchain_kernel(regs, entry);
                if (current->mm)
                        regs = task_pt_regs(current);
                else
                        regs = NULL;
        }
        if (regs) {
                flushw_user();
                if (test_thread_flag(TIF_32BIT))
                        perf_callchain_user_32(regs, entry);
                else
                        perf_callchain_user_64(regs, entry);
        }
        return entry;
}