Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/perfcou...

[deliverable/linux.git] / arch / x86 / kernel / cpu / perf_counter.c

/*
 * Performance counter x86 architecture code
 *
 *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
 *  Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
 *  Copyright (C) 2009 Jaswinder Singh Rajput
 *  Copyright (C) 2009 Advanced Micro Devices, Inc., Robert Richter
 *  Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
 *  Copyright (C) 2009 Intel Corporation, <markus.t.metzger@intel.com>
 *
 *  For licencing details see kernel-base/COPYING
 */

#include <linux/perf_counter.h>
#include <linux/capability.h>
#include <linux/notifier.h>
#include <linux/hardirq.h>
#include <linux/kprobes.h>
#include <linux/module.h>
#include <linux/kdebug.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include <linux/highmem.h>
#include <linux/cpu.h>

#include <asm/apic.h>
#include <asm/stacktrace.h>
#include <asm/nmi.h>

static u64 perf_counter_mask __read_mostly;

/* The maximal number of PEBS counters: */
#define MAX_PEBS_COUNTERS       4

/* The size of a BTS record in bytes: */
#define BTS_RECORD_SIZE         24

/* The size of a per-cpu BTS buffer in bytes: */
#define BTS_BUFFER_SIZE         (BTS_RECORD_SIZE * 1024)

/* The BTS overflow threshold in bytes from the end of the buffer: */
#define BTS_OVFL_TH             (BTS_RECORD_SIZE * 64)


/*
 * Bits in the debugctlmsr controlling branch tracing.
 */
#define X86_DEBUGCTL_TR                 (1 << 6)
#define X86_DEBUGCTL_BTS                (1 << 7)
#define X86_DEBUGCTL_BTINT              (1 << 8)
#define X86_DEBUGCTL_BTS_OFF_OS         (1 << 9)
#define X86_DEBUGCTL_BTS_OFF_USR        (1 << 10)

/*
 * A debug store configuration.
 *
 * We only support architectures that use 64bit fields.
 */
struct debug_store {
        u64     bts_buffer_base;
        u64     bts_index;
        u64     bts_absolute_maximum;
        u64     bts_interrupt_threshold;
        u64     pebs_buffer_base;
        u64     pebs_index;
        u64     pebs_absolute_maximum;
        u64     pebs_interrupt_threshold;
        u64     pebs_counter_reset[MAX_PEBS_COUNTERS];
};

struct cpu_hw_counters {
        struct perf_counter     *counters[X86_PMC_IDX_MAX];
        unsigned long           used_mask[BITS_TO_LONGS(X86_PMC_IDX_MAX)];
        unsigned long           active_mask[BITS_TO_LONGS(X86_PMC_IDX_MAX)];
        unsigned long           interrupts;
        int                     enabled;
        struct debug_store      *ds;
};

/*
 * struct x86_pmu - generic x86 pmu
 */
struct x86_pmu {
        const char      *name;
        int             version;
        int             (*handle_irq)(struct pt_regs *);
        void            (*disable_all)(void);
        void            (*enable_all)(void);
        void            (*enable)(struct hw_perf_counter *, int);
        void            (*disable)(struct hw_perf_counter *, int);
        unsigned        eventsel;
        unsigned        perfctr;
        u64             (*event_map)(int);
        u64             (*raw_event)(u64);
        int             max_events;
        int             num_counters;
        int             num_counters_fixed;
        int             counter_bits;
        u64             counter_mask;
        int             apic;
        u64             max_period;
        u64             intel_ctrl;
        void            (*enable_bts)(u64 config);
        void            (*disable_bts)(void);
};

static struct x86_pmu x86_pmu __read_mostly;

static DEFINE_PER_CPU(struct cpu_hw_counters, cpu_hw_counters) = {
        .enabled = 1,
};

/*
 * Not sure about some of these
 */
static const u64 p6_perfmon_event_map[] =
{
  [PERF_COUNT_HW_CPU_CYCLES]            = 0x0079,
  [PERF_COUNT_HW_INSTRUCTIONS]          = 0x00c0,
  [PERF_COUNT_HW_CACHE_REFERENCES]      = 0x0f2e,
  [PERF_COUNT_HW_CACHE_MISSES]          = 0x012e,
  [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]   = 0x00c4,
  [PERF_COUNT_HW_BRANCH_MISSES]         = 0x00c5,
  [PERF_COUNT_HW_BUS_CYCLES]            = 0x0062,
};

static u64 p6_pmu_event_map(int event)
{
        return p6_perfmon_event_map[event];
}

/*
 * Counter setting that is specified not to count anything.
 * We use this to effectively disable a counter.
 *
 * L2_RQSTS with 0 MESI unit mask.
 */
#define P6_NOP_COUNTER                  0x0000002EULL

static u64 p6_pmu_raw_event(u64 event)
{
#define P6_EVNTSEL_EVENT_MASK           0x000000FFULL
#define P6_EVNTSEL_UNIT_MASK            0x0000FF00ULL
#define P6_EVNTSEL_EDGE_MASK            0x00040000ULL
#define P6_EVNTSEL_INV_MASK             0x00800000ULL
#define P6_EVNTSEL_COUNTER_MASK         0xFF000000ULL

#define P6_EVNTSEL_MASK                 \
        (P6_EVNTSEL_EVENT_MASK |        \
         P6_EVNTSEL_UNIT_MASK  |        \
         P6_EVNTSEL_EDGE_MASK  |        \
         P6_EVNTSEL_INV_MASK   |        \
         P6_EVNTSEL_COUNTER_MASK)

        return event & P6_EVNTSEL_MASK;
}


/*
 * Intel PerfMon v3. Used on Core2 and later.
 */
static const u64 intel_perfmon_event_map[] =
{
  [PERF_COUNT_HW_CPU_CYCLES]            = 0x003c,
  [PERF_COUNT_HW_INSTRUCTIONS]          = 0x00c0,
  [PERF_COUNT_HW_CACHE_REFERENCES]      = 0x4f2e,
  [PERF_COUNT_HW_CACHE_MISSES]          = 0x412e,
  [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]   = 0x00c4,
  [PERF_COUNT_HW_BRANCH_MISSES]         = 0x00c5,
  [PERF_COUNT_HW_BUS_CYCLES]            = 0x013c,
};

static u64 intel_pmu_event_map(int event)
{
        return intel_perfmon_event_map[event];
}

/*
 * Generalized hw caching related event table, filled
 * in on a per model basis. A value of 0 means
 * 'not supported', -1 means 'event makes no sense on
 * this CPU', any other value means the raw event
 * ID.
 */

#define C(x) PERF_COUNT_HW_CACHE_##x

static u64 __read_mostly hw_cache_event_ids
                                [PERF_COUNT_HW_CACHE_MAX]
                                [PERF_COUNT_HW_CACHE_OP_MAX]
                                [PERF_COUNT_HW_CACHE_RESULT_MAX];

static const u64 nehalem_hw_cache_event_ids
                                [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) ] = 0x0f40, /* L1D_CACHE_LD.MESI            */
                [ C(RESULT_MISS)   ] = 0x0140, /* L1D_CACHE_LD.I_STATE         */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = 0x0f41, /* L1D_CACHE_ST.MESI            */
                [ C(RESULT_MISS)   ] = 0x0141, /* L1D_CACHE_ST.I_STATE         */
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0x014e, /* L1D_PREFETCH.REQUESTS        */
                [ C(RESULT_MISS)   ] = 0x024e, /* L1D_PREFETCH.MISS            */
        },
 },
 [ C(L1I ) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x0380, /* L1I.READS                    */
                [ C(RESULT_MISS)   ] = 0x0280, /* L1I.MISSES                   */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0x0,
                [ C(RESULT_MISS)   ] = 0x0,
        },
 },
 [ C(LL  ) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x0324, /* L2_RQSTS.LOADS               */
                [ C(RESULT_MISS)   ] = 0x0224, /* L2_RQSTS.LD_MISS             */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = 0x0c24, /* L2_RQSTS.RFOS                */
                [ C(RESULT_MISS)   ] = 0x0824, /* L2_RQSTS.RFO_MISS            */
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0x4f2e, /* LLC Reference                */
                [ C(RESULT_MISS)   ] = 0x412e, /* LLC Misses                   */
        },
 },
 [ C(DTLB) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x0f40, /* L1D_CACHE_LD.MESI   (alias)  */
                [ C(RESULT_MISS)   ] = 0x0108, /* DTLB_LOAD_MISSES.ANY         */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = 0x0f41, /* L1D_CACHE_ST.MESI   (alias)  */
                [ C(RESULT_MISS)   ] = 0x010c, /* MEM_STORE_RETIRED.DTLB_MISS  */
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0x0,
                [ C(RESULT_MISS)   ] = 0x0,
        },
 },
 [ C(ITLB) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x01c0, /* INST_RETIRED.ANY_P           */
                [ C(RESULT_MISS)   ] = 0x20c8, /* ITLB_MISS_RETIRED            */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
 },
 [ C(BPU ) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x00c4, /* BR_INST_RETIRED.ALL_BRANCHES */
                [ C(RESULT_MISS)   ] = 0x03e8, /* BPU_CLEARS.ANY               */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
 },
};

static const u64 core2_hw_cache_event_ids
                                [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) ] = 0x0f40, /* L1D_CACHE_LD.MESI          */
                [ C(RESULT_MISS)   ] = 0x0140, /* L1D_CACHE_LD.I_STATE       */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = 0x0f41, /* L1D_CACHE_ST.MESI          */
                [ C(RESULT_MISS)   ] = 0x0141, /* L1D_CACHE_ST.I_STATE       */
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0x104e, /* L1D_PREFETCH.REQUESTS      */
                [ C(RESULT_MISS)   ] = 0,
        },
 },
 [ C(L1I ) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x0080, /* L1I.READS                  */
                [ C(RESULT_MISS)   ] = 0x0081, /* L1I.MISSES                 */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0,
                [ C(RESULT_MISS)   ] = 0,
        },
 },
 [ C(LL  ) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x4f29, /* L2_LD.MESI                 */
                [ C(RESULT_MISS)   ] = 0x4129, /* L2_LD.ISTATE               */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = 0x4f2A, /* L2_ST.MESI                 */
                [ C(RESULT_MISS)   ] = 0x412A, /* L2_ST.ISTATE               */
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0,
                [ C(RESULT_MISS)   ] = 0,
        },
 },
 [ C(DTLB) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x0f40, /* L1D_CACHE_LD.MESI  (alias) */
                [ C(RESULT_MISS)   ] = 0x0208, /* DTLB_MISSES.MISS_LD        */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = 0x0f41, /* L1D_CACHE_ST.MESI  (alias) */
                [ C(RESULT_MISS)   ] = 0x0808, /* DTLB_MISSES.MISS_ST        */
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0,
                [ C(RESULT_MISS)   ] = 0,
        },
 },
 [ C(ITLB) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x00c0, /* INST_RETIRED.ANY_P         */
                [ C(RESULT_MISS)   ] = 0x1282, /* ITLBMISSES                 */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
 },
 [ C(BPU ) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x00c4, /* BR_INST_RETIRED.ANY        */
                [ C(RESULT_MISS)   ] = 0x00c5, /* BP_INST_RETIRED.MISPRED    */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
 },
};

static const u64 atom_hw_cache_event_ids
                                [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) ] = 0x2140, /* L1D_CACHE.LD               */
                [ C(RESULT_MISS)   ] = 0,
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = 0x2240, /* L1D_CACHE.ST               */
                [ C(RESULT_MISS)   ] = 0,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0x0,
                [ C(RESULT_MISS)   ] = 0,
        },
 },
 [ C(L1I ) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x0380, /* L1I.READS                  */
                [ C(RESULT_MISS)   ] = 0x0280, /* L1I.MISSES                 */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0,
                [ C(RESULT_MISS)   ] = 0,
        },
 },
 [ C(LL  ) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x4f29, /* L2_LD.MESI                 */
                [ C(RESULT_MISS)   ] = 0x4129, /* L2_LD.ISTATE               */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = 0x4f2A, /* L2_ST.MESI                 */
                [ C(RESULT_MISS)   ] = 0x412A, /* L2_ST.ISTATE               */
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0,
                [ C(RESULT_MISS)   ] = 0,
        },
 },
 [ C(DTLB) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x2140, /* L1D_CACHE_LD.MESI  (alias) */
                [ C(RESULT_MISS)   ] = 0x0508, /* DTLB_MISSES.MISS_LD        */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = 0x2240, /* L1D_CACHE_ST.MESI  (alias) */
                [ C(RESULT_MISS)   ] = 0x0608, /* DTLB_MISSES.MISS_ST        */
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0,
                [ C(RESULT_MISS)   ] = 0,
        },
 },
 [ C(ITLB) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x00c0, /* INST_RETIRED.ANY_P         */
                [ C(RESULT_MISS)   ] = 0x0282, /* ITLB.MISSES                */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
 },
 [ C(BPU ) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x00c4, /* BR_INST_RETIRED.ANY        */
                [ C(RESULT_MISS)   ] = 0x00c5, /* BP_INST_RETIRED.MISPRED    */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
 },
};

static u64 intel_pmu_raw_event(u64 event)
{
#define CORE_EVNTSEL_EVENT_MASK         0x000000FFULL
#define CORE_EVNTSEL_UNIT_MASK          0x0000FF00ULL
#define CORE_EVNTSEL_EDGE_MASK          0x00040000ULL
#define CORE_EVNTSEL_INV_MASK           0x00800000ULL
#define CORE_EVNTSEL_COUNTER_MASK       0xFF000000ULL

#define CORE_EVNTSEL_MASK               \
        (CORE_EVNTSEL_EVENT_MASK |      \
         CORE_EVNTSEL_UNIT_MASK  |      \
         CORE_EVNTSEL_EDGE_MASK  |      \
         CORE_EVNTSEL_INV_MASK  |       \
         CORE_EVNTSEL_COUNTER_MASK)

        return event & CORE_EVNTSEL_MASK;
}

static const u64 amd_hw_cache_event_ids
                                [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) ] = 0x0040, /* Data Cache Accesses        */
                [ C(RESULT_MISS)   ] = 0x0041, /* Data Cache Misses          */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = 0x0142, /* Data Cache Refills :system */
                [ C(RESULT_MISS)   ] = 0,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0x0267, /* Data Prefetcher :attempts  */
                [ C(RESULT_MISS)   ] = 0x0167, /* Data Prefetcher :cancelled */
        },
 },
 [ C(L1I ) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x0080, /* Instruction cache fetches  */
                [ C(RESULT_MISS)   ] = 0x0081, /* Instruction cache misses   */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0x014B, /* Prefetch Instructions :Load */
                [ C(RESULT_MISS)   ] = 0,
        },
 },
 [ C(LL  ) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x037D, /* Requests to L2 Cache :IC+DC */
                [ C(RESULT_MISS)   ] = 0x037E, /* L2 Cache Misses : IC+DC     */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = 0x017F, /* L2 Fill/Writeback           */
                [ C(RESULT_MISS)   ] = 0,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0,
                [ C(RESULT_MISS)   ] = 0,
        },
 },
 [ C(DTLB) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x0040, /* Data Cache Accesses        */
                [ C(RESULT_MISS)   ] = 0x0046, /* L1 DTLB and L2 DLTB Miss   */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = 0,
                [ C(RESULT_MISS)   ] = 0,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = 0,
                [ C(RESULT_MISS)   ] = 0,
        },
 },
 [ C(ITLB) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x0080, /* Instruction fecthes        */
                [ C(RESULT_MISS)   ] = 0x0085, /* Instr. fetch ITLB misses   */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
 },
 [ C(BPU ) ] = {
        [ C(OP_READ) ] = {
                [ C(RESULT_ACCESS) ] = 0x00c2, /* Retired Branch Instr.      */
                [ C(RESULT_MISS)   ] = 0x00c3, /* Retired Mispredicted BI    */
        },
        [ C(OP_WRITE) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
        [ C(OP_PREFETCH) ] = {
                [ C(RESULT_ACCESS) ] = -1,
                [ C(RESULT_MISS)   ] = -1,
        },
 },
};

/*
 * AMD Performance Monitor K7 and later.
 */
static const u64 amd_perfmon_event_map[] =
{
  [PERF_COUNT_HW_CPU_CYCLES]            = 0x0076,
  [PERF_COUNT_HW_INSTRUCTIONS]          = 0x00c0,
  [PERF_COUNT_HW_CACHE_REFERENCES]      = 0x0080,
  [PERF_COUNT_HW_CACHE_MISSES]          = 0x0081,
  [PERF_COUNT_HW_BRANCH_INSTRUCTIONS]   = 0x00c4,
  [PERF_COUNT_HW_BRANCH_MISSES]         = 0x00c5,
};

static u64 amd_pmu_event_map(int event)
{
        return amd_perfmon_event_map[event];
}

static u64 amd_pmu_raw_event(u64 event)
{
#define K7_EVNTSEL_EVENT_MASK   0x7000000FFULL
#define K7_EVNTSEL_UNIT_MASK    0x00000FF00ULL
#define K7_EVNTSEL_EDGE_MASK    0x000040000ULL
#define K7_EVNTSEL_INV_MASK     0x000800000ULL
#define K7_EVNTSEL_COUNTER_MASK 0x0FF000000ULL

#define K7_EVNTSEL_MASK                 \
        (K7_EVNTSEL_EVENT_MASK |        \
         K7_EVNTSEL_UNIT_MASK  |        \
         K7_EVNTSEL_EDGE_MASK  |        \
         K7_EVNTSEL_INV_MASK   |        \
         K7_EVNTSEL_COUNTER_MASK)

        return event & K7_EVNTSEL_MASK;
}

/*
 * Propagate counter elapsed time into the generic counter.
 * Can only be executed on the CPU where the counter is active.
 * Returns the delta events processed.
 */
static u64
x86_perf_counter_update(struct perf_counter *counter,
                        struct hw_perf_counter *hwc, int idx)
{
        int shift = 64 - x86_pmu.counter_bits;
        u64 prev_raw_count, new_raw_count;
        s64 delta;

        if (idx == X86_PMC_IDX_FIXED_BTS)
                return 0;

        /*
         * Careful: an NMI might modify the previous counter value.
         *
         * Our tactic to handle this is to first atomically read and
         * exchange a new raw count - then add that new-prev delta
         * count to the generic counter atomically:
         */
again:
        prev_raw_count = atomic64_read(&hwc->prev_count);
        rdmsrl(hwc->counter_base + idx, new_raw_count);

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

        /*
         * Now we have the new raw value and have updated the prev
         * timestamp already. We can now calculate the elapsed delta
         * (counter-)time and add that to the generic counter.
         *
         * Careful, not all hw sign-extends above the physical width
         * of the count.
         */
        delta = (new_raw_count << shift) - (prev_raw_count << shift);
        delta >>= shift;

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

        return new_raw_count;
}

static atomic_t active_counters;
static DEFINE_MUTEX(pmc_reserve_mutex);

static bool reserve_pmc_hardware(void)
{
#ifdef CONFIG_X86_LOCAL_APIC
        int i;

        if (nmi_watchdog == NMI_LOCAL_APIC)
                disable_lapic_nmi_watchdog();

        for (i = 0; i < x86_pmu.num_counters; i++) {
                if (!reserve_perfctr_nmi(x86_pmu.perfctr + i))
                        goto perfctr_fail;
        }

        for (i = 0; i < x86_pmu.num_counters; i++) {
                if (!reserve_evntsel_nmi(x86_pmu.eventsel + i))
                        goto eventsel_fail;
        }
#endif

        return true;

#ifdef CONFIG_X86_LOCAL_APIC
eventsel_fail:
        for (i--; i >= 0; i--)
                release_evntsel_nmi(x86_pmu.eventsel + i);

        i = x86_pmu.num_counters;

perfctr_fail:
        for (i--; i >= 0; i--)
                release_perfctr_nmi(x86_pmu.perfctr + i);

        if (nmi_watchdog == NMI_LOCAL_APIC)
                enable_lapic_nmi_watchdog();

        return false;
#endif
}

static void release_pmc_hardware(void)
{
#ifdef CONFIG_X86_LOCAL_APIC
        int i;

        for (i = 0; i < x86_pmu.num_counters; i++) {
                release_perfctr_nmi(x86_pmu.perfctr + i);
                release_evntsel_nmi(x86_pmu.eventsel + i);
        }

        if (nmi_watchdog == NMI_LOCAL_APIC)
                enable_lapic_nmi_watchdog();
#endif
}

static inline bool bts_available(void)
{
        return x86_pmu.enable_bts != NULL;
}

static inline void init_debug_store_on_cpu(int cpu)
{
        struct debug_store *ds = per_cpu(cpu_hw_counters, cpu).ds;

        if (!ds)
                return;

        wrmsr_on_cpu(cpu, MSR_IA32_DS_AREA,
                     (u32)((u64)(long)ds), (u32)((u64)(long)ds >> 32));
}

static inline void fini_debug_store_on_cpu(int cpu)
{
        if (!per_cpu(cpu_hw_counters, cpu).ds)
                return;

        wrmsr_on_cpu(cpu, MSR_IA32_DS_AREA, 0, 0);
}

static void release_bts_hardware(void)
{
        int cpu;

        if (!bts_available())
                return;

        get_online_cpus();

        for_each_online_cpu(cpu)
                fini_debug_store_on_cpu(cpu);

        for_each_possible_cpu(cpu) {
                struct debug_store *ds = per_cpu(cpu_hw_counters, cpu).ds;

                if (!ds)
                        continue;

                per_cpu(cpu_hw_counters, cpu).ds = NULL;

                kfree((void *)(long)ds->bts_buffer_base);
                kfree(ds);
        }

        put_online_cpus();
}

static int reserve_bts_hardware(void)
{
        int cpu, err = 0;

        if (!bts_available())
                return -EOPNOTSUPP;

        get_online_cpus();

        for_each_possible_cpu(cpu) {
                struct debug_store *ds;
                void *buffer;

                err = -ENOMEM;
                buffer = kzalloc(BTS_BUFFER_SIZE, GFP_KERNEL);
                if (unlikely(!buffer))
                        break;

                ds = kzalloc(sizeof(*ds), GFP_KERNEL);
                if (unlikely(!ds)) {
                        kfree(buffer);
                        break;
                }

                ds->bts_buffer_base = (u64)(long)buffer;
                ds->bts_index = ds->bts_buffer_base;
                ds->bts_absolute_maximum =
                        ds->bts_buffer_base + BTS_BUFFER_SIZE;
                ds->bts_interrupt_threshold =
                        ds->bts_absolute_maximum - BTS_OVFL_TH;

                per_cpu(cpu_hw_counters, cpu).ds = ds;
                err = 0;
        }

        if (err)
                release_bts_hardware();
        else {
                for_each_online_cpu(cpu)
                        init_debug_store_on_cpu(cpu);
        }

        put_online_cpus();

        return err;
}

static void hw_perf_counter_destroy(struct perf_counter *counter)
{
        if (atomic_dec_and_mutex_lock(&active_counters, &pmc_reserve_mutex)) {
                release_pmc_hardware();
                release_bts_hardware();
                mutex_unlock(&pmc_reserve_mutex);
        }
}

static inline int x86_pmu_initialized(void)
{
        return x86_pmu.handle_irq != NULL;
}

static inline int
set_ext_hw_attr(struct hw_perf_counter *hwc, struct perf_counter_attr *attr)
{
        unsigned int cache_type, cache_op, cache_result;
        u64 config, val;

        config = attr->config;

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

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

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

        val = hw_cache_event_ids[cache_type][cache_op][cache_result];

        if (val == 0)
                return -ENOENT;

        if (val == -1)
                return -EINVAL;

        hwc->config |= val;

        return 0;
}

static void intel_pmu_enable_bts(u64 config)
{
        unsigned long debugctlmsr;

        debugctlmsr = get_debugctlmsr();

        debugctlmsr |= X86_DEBUGCTL_TR;
        debugctlmsr |= X86_DEBUGCTL_BTS;
        debugctlmsr |= X86_DEBUGCTL_BTINT;

        if (!(config & ARCH_PERFMON_EVENTSEL_OS))
                debugctlmsr |= X86_DEBUGCTL_BTS_OFF_OS;

        if (!(config & ARCH_PERFMON_EVENTSEL_USR))
                debugctlmsr |= X86_DEBUGCTL_BTS_OFF_USR;

        update_debugctlmsr(debugctlmsr);
}

static void intel_pmu_disable_bts(void)
{
        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
        unsigned long debugctlmsr;

        if (!cpuc->ds)
                return;

        debugctlmsr = get_debugctlmsr();

        debugctlmsr &=
                ~(X86_DEBUGCTL_TR | X86_DEBUGCTL_BTS | X86_DEBUGCTL_BTINT |
                  X86_DEBUGCTL_BTS_OFF_OS | X86_DEBUGCTL_BTS_OFF_USR);

        update_debugctlmsr(debugctlmsr);
}

/*
 * Setup the hardware configuration for a given attr_type
 */
static int __hw_perf_counter_init(struct perf_counter *counter)
{
        struct perf_counter_attr *attr = &counter->attr;
        struct hw_perf_counter *hwc = &counter->hw;
        u64 config;
        int err;

        if (!x86_pmu_initialized())
                return -ENODEV;

        err = 0;
        if (!atomic_inc_not_zero(&active_counters)) {
                mutex_lock(&pmc_reserve_mutex);
                if (atomic_read(&active_counters) == 0) {
                        if (!reserve_pmc_hardware())
                                err = -EBUSY;
                        else
                                reserve_bts_hardware();
                }
                if (!err)
                        atomic_inc(&active_counters);
                mutex_unlock(&pmc_reserve_mutex);
        }
        if (err)
                return err;

        /*
         * Generate PMC IRQs:
         * (keep 'enabled' bit clear for now)
         */
        hwc->config = ARCH_PERFMON_EVENTSEL_INT;

        /*
         * Count user and OS events unless requested not to.
         */
        if (!attr->exclude_user)
                hwc->config |= ARCH_PERFMON_EVENTSEL_USR;
        if (!attr->exclude_kernel)
                hwc->config |= ARCH_PERFMON_EVENTSEL_OS;

        if (!hwc->sample_period) {
                hwc->sample_period = x86_pmu.max_period;
                hwc->last_period = hwc->sample_period;
                atomic64_set(&hwc->period_left, hwc->sample_period);
        } else {
                /*
                 * If we have a PMU initialized but no APIC
                 * interrupts, we cannot sample hardware
                 * counters (user-space has to fall back and
                 * sample via a hrtimer based software counter):
                 */
                if (!x86_pmu.apic)
                        return -EOPNOTSUPP;
        }

        counter->destroy = hw_perf_counter_destroy;

        /*
         * Raw event type provide the config in the event structure
         */
        if (attr->type == PERF_TYPE_RAW) {
                hwc->config |= x86_pmu.raw_event(attr->config);
                return 0;
        }

        if (attr->type == PERF_TYPE_HW_CACHE)
                return set_ext_hw_attr(hwc, attr);

        if (attr->config >= x86_pmu.max_events)
                return -EINVAL;

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

        if (config == 0)
                return -ENOENT;

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

        hwc->config |= config;

        return 0;
}

static void p6_pmu_disable_all(void)
{
        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
        u64 val;

        if (!cpuc->enabled)
                return;

        cpuc->enabled = 0;
        barrier();

        /* p6 only has one enable register */
        rdmsrl(MSR_P6_EVNTSEL0, val);
        val &= ~ARCH_PERFMON_EVENTSEL0_ENABLE;
        wrmsrl(MSR_P6_EVNTSEL0, val);
}

static void intel_pmu_disable_all(void)
{
        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);

        if (!cpuc->enabled)
                return;

        cpuc->enabled = 0;
        barrier();

        wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, 0);

        if (test_bit(X86_PMC_IDX_FIXED_BTS, cpuc->active_mask))
                intel_pmu_disable_bts();
}

static void amd_pmu_disable_all(void)
{
        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
        int idx;

        if (!cpuc->enabled)
                return;

        cpuc->enabled = 0;
        /*
         * ensure we write the disable before we start disabling the
         * counters proper, so that amd_pmu_enable_counter() does the
         * right thing.
         */
        barrier();

        for (idx = 0; idx < x86_pmu.num_counters; idx++) {
                u64 val;

                if (!test_bit(idx, cpuc->active_mask))
                        continue;
                rdmsrl(MSR_K7_EVNTSEL0 + idx, val);
                if (!(val & ARCH_PERFMON_EVENTSEL0_ENABLE))
                        continue;
                val &= ~ARCH_PERFMON_EVENTSEL0_ENABLE;
                wrmsrl(MSR_K7_EVNTSEL0 + idx, val);
        }
}

void hw_perf_disable(void)
{
        if (!x86_pmu_initialized())
                return;
        return x86_pmu.disable_all();
}

static void p6_pmu_enable_all(void)
{
        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
        unsigned long val;

        if (cpuc->enabled)
                return;

        cpuc->enabled = 1;
        barrier();

        /* p6 only has one enable register */
        rdmsrl(MSR_P6_EVNTSEL0, val);
        val |= ARCH_PERFMON_EVENTSEL0_ENABLE;
        wrmsrl(MSR_P6_EVNTSEL0, val);
}

static void intel_pmu_enable_all(void)
{
        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);

        if (cpuc->enabled)
                return;

        cpuc->enabled = 1;
        barrier();

        wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, x86_pmu.intel_ctrl);

        if (test_bit(X86_PMC_IDX_FIXED_BTS, cpuc->active_mask)) {
                struct perf_counter *counter =
                        cpuc->counters[X86_PMC_IDX_FIXED_BTS];

                if (WARN_ON_ONCE(!counter))
                        return;

                intel_pmu_enable_bts(counter->hw.config);
        }
}

static void amd_pmu_enable_all(void)
{
        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
        int idx;

        if (cpuc->enabled)
                return;

        cpuc->enabled = 1;
        barrier();

        for (idx = 0; idx < x86_pmu.num_counters; idx++) {
                struct perf_counter *counter = cpuc->counters[idx];
                u64 val;

                if (!test_bit(idx, cpuc->active_mask))
                        continue;

                val = counter->hw.config;
                val |= ARCH_PERFMON_EVENTSEL0_ENABLE;
                wrmsrl(MSR_K7_EVNTSEL0 + idx, val);
        }
}

void hw_perf_enable(void)
{
        if (!x86_pmu_initialized())
                return;
        x86_pmu.enable_all();
}

static inline u64 intel_pmu_get_status(void)
{
        u64 status;

        rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, status);

        return status;
}

static inline void intel_pmu_ack_status(u64 ack)
{
        wrmsrl(MSR_CORE_PERF_GLOBAL_OVF_CTRL, ack);
}

static inline void x86_pmu_enable_counter(struct hw_perf_counter *hwc, int idx)
{
        (void)checking_wrmsrl(hwc->config_base + idx,
                              hwc->config | ARCH_PERFMON_EVENTSEL0_ENABLE);
}

static inline void x86_pmu_disable_counter(struct hw_perf_counter *hwc, int idx)
{
        (void)checking_wrmsrl(hwc->config_base + idx, hwc->config);
}

static inline void
intel_pmu_disable_fixed(struct hw_perf_counter *hwc, int __idx)
{
        int idx = __idx - X86_PMC_IDX_FIXED;
        u64 ctrl_val, mask;

        mask = 0xfULL << (idx * 4);

        rdmsrl(hwc->config_base, ctrl_val);
        ctrl_val &= ~mask;
        (void)checking_wrmsrl(hwc->config_base, ctrl_val);
}

static inline void
p6_pmu_disable_counter(struct hw_perf_counter *hwc, int idx)
{
        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
        u64 val = P6_NOP_COUNTER;

        if (cpuc->enabled)
                val |= ARCH_PERFMON_EVENTSEL0_ENABLE;

        (void)checking_wrmsrl(hwc->config_base + idx, val);
}

static inline void
intel_pmu_disable_counter(struct hw_perf_counter *hwc, int idx)
{
        if (unlikely(idx == X86_PMC_IDX_FIXED_BTS)) {
                intel_pmu_disable_bts();
                return;
        }

        if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL)) {
                intel_pmu_disable_fixed(hwc, idx);
                return;
        }

        x86_pmu_disable_counter(hwc, idx);
}

static inline void
amd_pmu_disable_counter(struct hw_perf_counter *hwc, int idx)
{
        x86_pmu_disable_counter(hwc, idx);
}

static DEFINE_PER_CPU(u64, prev_left[X86_PMC_IDX_MAX]);

/*
 * Set the next IRQ period, based on the hwc->period_left value.
 * To be called with the counter disabled in hw:
 */
static int
x86_perf_counter_set_period(struct perf_counter *counter,
                             struct hw_perf_counter *hwc, int idx)
{
        s64 left = atomic64_read(&hwc->period_left);
        s64 period = hwc->sample_period;
        int err, ret = 0;

        if (idx == X86_PMC_IDX_FIXED_BTS)
                return 0;

        /*
         * If we are way outside a reasoable range then just skip forward:
         */
        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;
        }
        /*
         * Quirk: certain CPUs dont like it if just 1 event is left:
         */
        if (unlikely(left < 2))
                left = 2;

        if (left > x86_pmu.max_period)
                left = x86_pmu.max_period;

        per_cpu(prev_left[idx], smp_processor_id()) = left;

        /*
         * The hw counter starts counting from this counter offset,
         * mark it to be able to extra future deltas:
         */
        atomic64_set(&hwc->prev_count, (u64)-left);

        err = checking_wrmsrl(hwc->counter_base + idx,
                             (u64)(-left) & x86_pmu.counter_mask);

        perf_counter_update_userpage(counter);

        return ret;
}

static inline void
intel_pmu_enable_fixed(struct hw_perf_counter *hwc, int __idx)
{
        int idx = __idx - X86_PMC_IDX_FIXED;
        u64 ctrl_val, bits, mask;
        int err;

        /*
         * Enable IRQ generation (0x8),
         * and enable ring-3 counting (0x2) and ring-0 counting (0x1)
         * if requested:
         */
        bits = 0x8ULL;
        if (hwc->config & ARCH_PERFMON_EVENTSEL_USR)
                bits |= 0x2;
        if (hwc->config & ARCH_PERFMON_EVENTSEL_OS)
                bits |= 0x1;
        bits <<= (idx * 4);
        mask = 0xfULL << (idx * 4);

        rdmsrl(hwc->config_base, ctrl_val);
        ctrl_val &= ~mask;
        ctrl_val |= bits;
        err = checking_wrmsrl(hwc->config_base, ctrl_val);
}

static void p6_pmu_enable_counter(struct hw_perf_counter *hwc, int idx)
{
        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
        u64 val;

        val = hwc->config;
        if (cpuc->enabled)
                val |= ARCH_PERFMON_EVENTSEL0_ENABLE;

        (void)checking_wrmsrl(hwc->config_base + idx, val);
}


static void intel_pmu_enable_counter(struct hw_perf_counter *hwc, int idx)
{
        if (unlikely(idx == X86_PMC_IDX_FIXED_BTS)) {
                if (!__get_cpu_var(cpu_hw_counters).enabled)
                        return;

                intel_pmu_enable_bts(hwc->config);
                return;
        }

        if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL)) {
                intel_pmu_enable_fixed(hwc, idx);
                return;
        }

        x86_pmu_enable_counter(hwc, idx);
}

static void amd_pmu_enable_counter(struct hw_perf_counter *hwc, int idx)
{
        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);

        if (cpuc->enabled)
                x86_pmu_enable_counter(hwc, idx);
}

static int
fixed_mode_idx(struct perf_counter *counter, struct hw_perf_counter *hwc)
{
        unsigned int event;

        event = hwc->config & ARCH_PERFMON_EVENT_MASK;

        if (unlikely((event ==
                      x86_pmu.event_map(PERF_COUNT_HW_BRANCH_INSTRUCTIONS)) &&
                     (hwc->sample_period == 1)))
                return X86_PMC_IDX_FIXED_BTS;

        if (!x86_pmu.num_counters_fixed)
                return -1;

        if (unlikely(event == x86_pmu.event_map(PERF_COUNT_HW_INSTRUCTIONS)))
                return X86_PMC_IDX_FIXED_INSTRUCTIONS;
        if (unlikely(event == x86_pmu.event_map(PERF_COUNT_HW_CPU_CYCLES)))
                return X86_PMC_IDX_FIXED_CPU_CYCLES;
        if (unlikely(event == x86_pmu.event_map(PERF_COUNT_HW_BUS_CYCLES)))
                return X86_PMC_IDX_FIXED_BUS_CYCLES;

        return -1;
}

/*
 * Find a PMC slot for the freshly enabled / scheduled in counter:
 */
static int x86_pmu_enable(struct perf_counter *counter)
{
        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
        struct hw_perf_counter *hwc = &counter->hw;
        int idx;

        idx = fixed_mode_idx(counter, hwc);
        if (idx == X86_PMC_IDX_FIXED_BTS) {
                /*
                 * Try to use BTS for branch tracing. If that is not
                 * available, try to get a generic counter.
                 */
                if (unlikely(!cpuc->ds))
                        goto try_generic;

                /*
                 * Try to get the fixed counter, if that is already taken
                 * then try to get a generic counter:
                 */
                if (test_and_set_bit(idx, cpuc->used_mask))
                        goto try_generic;

                hwc->config_base        = 0;
                hwc->counter_base       = 0;
                hwc->idx                = idx;
        } else if (idx >= 0) {
                /*
                 * Try to get the fixed counter, if that is already taken
                 * then try to get a generic counter:
                 */
                if (test_and_set_bit(idx, cpuc->used_mask))
                        goto try_generic;

                hwc->config_base = MSR_ARCH_PERFMON_FIXED_CTR_CTRL;
                /*
                 * We set it so that counter_base + idx in wrmsr/rdmsr maps to
                 * MSR_ARCH_PERFMON_FIXED_CTR0 ... CTR2:
                 */
                hwc->counter_base =
                        MSR_ARCH_PERFMON_FIXED_CTR0 - X86_PMC_IDX_FIXED;
                hwc->idx = idx;
        } else {
                idx = hwc->idx;
                /* Try to get the previous generic counter again */
                if (test_and_set_bit(idx, cpuc->used_mask)) {
try_generic:
                        idx = find_first_zero_bit(cpuc->used_mask,
                                                  x86_pmu.num_counters);
                        if (idx == x86_pmu.num_counters)
                                return -EAGAIN;

                        set_bit(idx, cpuc->used_mask);
                        hwc->idx = idx;
                }
                hwc->config_base  = x86_pmu.eventsel;
                hwc->counter_base = x86_pmu.perfctr;
        }

        perf_counters_lapic_init();

        x86_pmu.disable(hwc, idx);

        cpuc->counters[idx] = counter;
        set_bit(idx, cpuc->active_mask);

        x86_perf_counter_set_period(counter, hwc, idx);
        x86_pmu.enable(hwc, idx);

        perf_counter_update_userpage(counter);

        return 0;
}

static void x86_pmu_unthrottle(struct perf_counter *counter)
{
        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
        struct hw_perf_counter *hwc = &counter->hw;

        if (WARN_ON_ONCE(hwc->idx >= X86_PMC_IDX_MAX ||
                                cpuc->counters[hwc->idx] != counter))
                return;

        x86_pmu.enable(hwc, hwc->idx);
}

void perf_counter_print_debug(void)
{
        u64 ctrl, status, overflow, pmc_ctrl, pmc_count, prev_left, fixed;
        struct cpu_hw_counters *cpuc;
        unsigned long flags;
        int cpu, idx;

        if (!x86_pmu.num_counters)
                return;

        local_irq_save(flags);

        cpu = smp_processor_id();
        cpuc = &per_cpu(cpu_hw_counters, cpu);

        if (x86_pmu.version >= 2) {
                rdmsrl(MSR_CORE_PERF_GLOBAL_CTRL, ctrl);
                rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, status);
                rdmsrl(MSR_CORE_PERF_GLOBAL_OVF_CTRL, overflow);
                rdmsrl(MSR_ARCH_PERFMON_FIXED_CTR_CTRL, fixed);

                pr_info("\n");
                pr_info("CPU#%d: ctrl:       %016llx\n", cpu, ctrl);
                pr_info("CPU#%d: status:     %016llx\n", cpu, status);
                pr_info("CPU#%d: overflow:   %016llx\n", cpu, overflow);
                pr_info("CPU#%d: fixed:      %016llx\n", cpu, fixed);
        }
        pr_info("CPU#%d: used:       %016llx\n", cpu, *(u64 *)cpuc->used_mask);

        for (idx = 0; idx < x86_pmu.num_counters; idx++) {
                rdmsrl(x86_pmu.eventsel + idx, pmc_ctrl);
                rdmsrl(x86_pmu.perfctr  + idx, pmc_count);

                prev_left = per_cpu(prev_left[idx], cpu);

                pr_info("CPU#%d:   gen-PMC%d ctrl:  %016llx\n",
                        cpu, idx, pmc_ctrl);
                pr_info("CPU#%d:   gen-PMC%d count: %016llx\n",
                        cpu, idx, pmc_count);
                pr_info("CPU#%d:   gen-PMC%d left:  %016llx\n",
                        cpu, idx, prev_left);
        }
        for (idx = 0; idx < x86_pmu.num_counters_fixed; idx++) {
                rdmsrl(MSR_ARCH_PERFMON_FIXED_CTR0 + idx, pmc_count);

                pr_info("CPU#%d: fixed-PMC%d count: %016llx\n",
                        cpu, idx, pmc_count);
        }
        local_irq_restore(flags);
}

static void intel_pmu_drain_bts_buffer(struct cpu_hw_counters *cpuc,
                                       struct perf_sample_data *data)
{
        struct debug_store *ds = cpuc->ds;
        struct bts_record {
                u64     from;
                u64     to;
                u64     flags;
        };
        struct perf_counter *counter = cpuc->counters[X86_PMC_IDX_FIXED_BTS];
        unsigned long orig_ip = data->regs->ip;
        u64 at;

        if (!counter)
                return;

        if (!ds)
                return;

        for (at = ds->bts_buffer_base;
             at < ds->bts_index;
             at += sizeof(struct bts_record)) {
                struct bts_record *rec = (struct bts_record *)(long)at;

                data->regs->ip  = rec->from;
                data->addr      = rec->to;

                perf_counter_output(counter, 1, data);
        }

        ds->bts_index = ds->bts_buffer_base;

        data->regs->ip  = orig_ip;
        data->addr      = 0;

        /* There's new data available. */
        counter->pending_kill = POLL_IN;
}

static void x86_pmu_disable(struct perf_counter *counter)
{
        struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters);
        struct hw_perf_counter *hwc = &counter->hw;
        int idx = hwc->idx;

        /*
         * Must be done before we disable, otherwise the nmi handler
         * could reenable again:
         */
        clear_bit(idx, cpuc->active_mask);
        x86_pmu.disable(hwc, idx);

        /*
         * Make sure the cleared pointer becomes visible before we
         * (potentially) free the counter:
         */
        barrier();

        /*
         * Drain the remaining delta count out of a counter
         * that we are disabling:
         */
        x86_perf_counter_update(counter, hwc, idx);

        /* Drain the remaining BTS records. */
        if (unlikely(idx == X86_PMC_IDX_FIXED_BTS)) {
                struct perf_sample_data data;
                struct pt_regs regs;

                data.regs = &regs;
                intel_pmu_drain_bts_buffer(cpuc, &data);
        }
        cpuc->counters[idx] = NULL;
        clear_bit(idx, cpuc->used_mask);

        perf_counter_update_userpage(counter);
}

/*
 * Save and restart an expired counter. Called by NMI contexts,
 * so it has to be careful about preempting normal counter ops:
 */
static int intel_pmu_save_and_restart(struct perf_counter *counter)
{
        struct hw_perf_counter *hwc = &counter->hw;
        int idx = hwc->idx;
        int ret;

        x86_perf_counter_update(counter, hwc, idx);
        ret = x86_perf_counter_set_period(counter, hwc, idx);

        if (counter->state == PERF_COUNTER_STATE_ACTIVE)
                intel_pmu_enable_counter(hwc, idx);

        return ret;
}

static void intel_pmu_reset(void)
{
        struct debug_store *ds = __get_cpu_var(cpu_hw_counters).ds;
        unsigned long flags;
        int idx;

        if (!x86_pmu.num_counters)
                return;

        local_irq_save(flags);

        printk("clearing PMU state on CPU#%d\n", smp_processor_id());

        for (idx = 0; idx < x86_pmu.num_counters; idx++) {
                checking_wrmsrl(x86_pmu.eventsel + idx, 0ull);
                checking_wrmsrl(x86_pmu.perfctr  + idx, 0ull);
        }
        for (idx = 0; idx < x86_pmu.num_counters_fixed; idx++) {
                checking_wrmsrl(MSR_ARCH_PERFMON_FIXED_CTR0 + idx, 0ull);
        }
        if (ds)
                ds->bts_index = ds->bts_buffer_base;

        local_irq_restore(flags);
}

static int p6_pmu_handle_irq(struct pt_regs *regs)
{
        struct perf_sample_data data;
        struct cpu_hw_counters *cpuc;
        struct perf_counter *counter;
        struct hw_perf_counter *hwc;
        int idx, handled = 0;
        u64 val;

        data.regs = regs;
        data.addr = 0;

        cpuc = &__get_cpu_var(cpu_hw_counters);

        for (idx = 0; idx < x86_pmu.num_counters; idx++) {
                if (!test_bit(idx, cpuc->active_mask))
                        continue;

                counter = cpuc->counters[idx];
                hwc = &counter->hw;

                val = x86_perf_counter_update(counter, hwc, idx);
                if (val & (1ULL << (x86_pmu.counter_bits - 1)))
                        continue;

                /*
                 * counter overflow
                 */
                handled         = 1;
                data.period     = counter->hw.last_period;

                if (!x86_perf_counter_set_period(counter, hwc, idx))
                        continue;

                if (perf_counter_overflow(counter, 1, &data))
                        p6_pmu_disable_counter(hwc, idx);
        }

        if (handled)
                inc_irq_stat(apic_perf_irqs);

        return handled;
}

/*
 * This handler is triggered by the local APIC, so the APIC IRQ handling
 * rules apply:
 */
static int intel_pmu_handle_irq(struct pt_regs *regs)
{
        struct perf_sample_data data;
        struct cpu_hw_counters *cpuc;
        int bit, loops;
        u64 ack, status;

        data.regs = regs;
        data.addr = 0;

        cpuc = &__get_cpu_var(cpu_hw_counters);

        perf_disable();
        intel_pmu_drain_bts_buffer(cpuc, &data);
        status = intel_pmu_get_status();
        if (!status) {
                perf_enable();
                return 0;
        }

        loops = 0;
again:
        if (++loops > 100) {
                WARN_ONCE(1, "perfcounters: irq loop stuck!\n");
                perf_counter_print_debug();
                intel_pmu_reset();
                perf_enable();
                return 1;
        }

        inc_irq_stat(apic_perf_irqs);
        ack = status;
        for_each_bit(bit, (unsigned long *)&status, X86_PMC_IDX_MAX) {
                struct perf_counter *counter = cpuc->counters[bit];

                clear_bit(bit, (unsigned long *) &status);
                if (!test_bit(bit, cpuc->active_mask))
                        continue;

                if (!intel_pmu_save_and_restart(counter))
                        continue;

                data.period = counter->hw.last_period;

                if (perf_counter_overflow(counter, 1, &data))
                        intel_pmu_disable_counter(&counter->hw, bit);
        }

        intel_pmu_ack_status(ack);

        /*
         * Repeat if there is more work to be done:
         */
        status = intel_pmu_get_status();
        if (status)
                goto again;

        perf_enable();

        return 1;
}

static int amd_pmu_handle_irq(struct pt_regs *regs)
{
        struct perf_sample_data data;
        struct cpu_hw_counters *cpuc;
        struct perf_counter *counter;
        struct hw_perf_counter *hwc;
        int idx, handled = 0;
        u64 val;

        data.regs = regs;
        data.addr = 0;

        cpuc = &__get_cpu_var(cpu_hw_counters);

        for (idx = 0; idx < x86_pmu.num_counters; idx++) {
                if (!test_bit(idx, cpuc->active_mask))
                        continue;

                counter = cpuc->counters[idx];
                hwc = &counter->hw;

                val = x86_perf_counter_update(counter, hwc, idx);
                if (val & (1ULL << (x86_pmu.counter_bits - 1)))
                        continue;

                /*
                 * counter overflow
                 */
                handled         = 1;
                data.period     = counter->hw.last_period;

                if (!x86_perf_counter_set_period(counter, hwc, idx))
                        continue;

                if (perf_counter_overflow(counter, 1, &data))
                        amd_pmu_disable_counter(hwc, idx);
        }

        if (handled)
                inc_irq_stat(apic_perf_irqs);

        return handled;
}

void smp_perf_pending_interrupt(struct pt_regs *regs)
{
        irq_enter();
        ack_APIC_irq();
        inc_irq_stat(apic_pending_irqs);
        perf_counter_do_pending();
        irq_exit();
}

void set_perf_counter_pending(void)
{
#ifdef CONFIG_X86_LOCAL_APIC
        apic->send_IPI_self(LOCAL_PENDING_VECTOR);
#endif
}

void perf_counters_lapic_init(void)
{
#ifdef CONFIG_X86_LOCAL_APIC
        if (!x86_pmu.apic || !x86_pmu_initialized())
                return;

        /*
         * Always use NMI for PMU
         */
        apic_write(APIC_LVTPC, APIC_DM_NMI);
#endif
}

static int __kprobes
perf_counter_nmi_handler(struct notifier_block *self,
                         unsigned long cmd, void *__args)
{
        struct die_args *args = __args;
        struct pt_regs *regs;

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

        switch (cmd) {
        case DIE_NMI:
        case DIE_NMI_IPI:
                break;

        default:
                return NOTIFY_DONE;
        }

        regs = args->regs;

#ifdef CONFIG_X86_LOCAL_APIC
        apic_write(APIC_LVTPC, APIC_DM_NMI);
#endif
        /*
         * Can't rely on the handled return value to say it was our NMI, two
         * counters could trigger 'simultaneously' raising two back-to-back NMIs.
         *
         * If the first NMI handles both, the latter will be empty and daze
         * the CPU.
         */
        x86_pmu.handle_irq(regs);

        return NOTIFY_STOP;
}

static __read_mostly struct notifier_block perf_counter_nmi_notifier = {
        .notifier_call          = perf_counter_nmi_handler,
        .next                   = NULL,
        .priority               = 1
};

static struct x86_pmu p6_pmu = {
        .name                   = "p6",
        .handle_irq             = p6_pmu_handle_irq,
        .disable_all            = p6_pmu_disable_all,
        .enable_all             = p6_pmu_enable_all,
        .enable                 = p6_pmu_enable_counter,
        .disable                = p6_pmu_disable_counter,
        .eventsel               = MSR_P6_EVNTSEL0,
        .perfctr                = MSR_P6_PERFCTR0,
        .event_map              = p6_pmu_event_map,
        .raw_event              = p6_pmu_raw_event,
        .max_events             = ARRAY_SIZE(p6_perfmon_event_map),
        .apic                   = 1,
        .max_period             = (1ULL << 31) - 1,
        .version                = 0,
        .num_counters           = 2,
        /*
         * Counters have 40 bits implemented. However they are designed such
         * that bits [32-39] are sign extensions of bit 31. As such the
         * effective width of a counter for P6-like PMU is 32 bits only.
         *
         * See IA-32 Intel Architecture Software developer manual Vol 3B
         */
        .counter_bits           = 32,
        .counter_mask           = (1ULL << 32) - 1,
};

static struct x86_pmu intel_pmu = {
        .name                   = "Intel",
        .handle_irq             = intel_pmu_handle_irq,
        .disable_all            = intel_pmu_disable_all,
        .enable_all             = intel_pmu_enable_all,
        .enable                 = intel_pmu_enable_counter,
        .disable                = intel_pmu_disable_counter,
        .eventsel               = MSR_ARCH_PERFMON_EVENTSEL0,
        .perfctr                = MSR_ARCH_PERFMON_PERFCTR0,
        .event_map              = intel_pmu_event_map,
        .raw_event              = intel_pmu_raw_event,
        .max_events             = ARRAY_SIZE(intel_perfmon_event_map),
        .apic                   = 1,
        /*
         * Intel PMCs cannot be accessed sanely above 32 bit width,
         * so we install an artificial 1<<31 period regardless of
         * the generic counter period:
         */
        .max_period             = (1ULL << 31) - 1,
        .enable_bts             = intel_pmu_enable_bts,
        .disable_bts            = intel_pmu_disable_bts,
};

static struct x86_pmu amd_pmu = {
        .name                   = "AMD",
        .handle_irq             = amd_pmu_handle_irq,
        .disable_all            = amd_pmu_disable_all,
        .enable_all             = amd_pmu_enable_all,
        .enable                 = amd_pmu_enable_counter,
        .disable                = amd_pmu_disable_counter,
        .eventsel               = MSR_K7_EVNTSEL0,
        .perfctr                = MSR_K7_PERFCTR0,
        .event_map              = amd_pmu_event_map,
        .raw_event              = amd_pmu_raw_event,
        .max_events             = ARRAY_SIZE(amd_perfmon_event_map),
        .num_counters           = 4,
        .counter_bits           = 48,
        .counter_mask           = (1ULL << 48) - 1,
        .apic                   = 1,
        /* use highest bit to detect overflow */
        .max_period             = (1ULL << 47) - 1,
};

static int p6_pmu_init(void)
{
        switch (boot_cpu_data.x86_model) {
        case 1:
        case 3:  /* Pentium Pro */
        case 5:
        case 6:  /* Pentium II */
        case 7:
        case 8:
        case 11: /* Pentium III */
                break;
        case 9:
        case 13:
                /* Pentium M */
                break;
        default:
                pr_cont("unsupported p6 CPU model %d ",
                        boot_cpu_data.x86_model);
                return -ENODEV;
        }

        x86_pmu = p6_pmu;

        if (!cpu_has_apic) {
                pr_info("no APIC, boot with the \"lapic\" boot parameter to force-enable it.\n");
                pr_info("no hardware sampling interrupt available.\n");
                x86_pmu.apic = 0;
        }

        return 0;
}

static int intel_pmu_init(void)
{
        union cpuid10_edx edx;
        union cpuid10_eax eax;
        unsigned int unused;
        unsigned int ebx;
        int version;

        if (!cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON)) {
                /* check for P6 processor family */
           if (boot_cpu_data.x86 == 6) {
                return p6_pmu_init();
           } else {
                return -ENODEV;
           }
        }

        /*
         * Check whether the Architectural PerfMon supports
         * Branch Misses Retired Event or not.
         */
        cpuid(10, &eax.full, &ebx, &unused, &edx.full);
        if (eax.split.mask_length <= ARCH_PERFMON_BRANCH_MISSES_RETIRED)
                return -ENODEV;

        version = eax.split.version_id;
        if (version < 2)
                return -ENODEV;

        x86_pmu                         = intel_pmu;
        x86_pmu.version                 = version;
        x86_pmu.num_counters            = eax.split.num_counters;
        x86_pmu.counter_bits            = eax.split.bit_width;
        x86_pmu.counter_mask            = (1ULL << eax.split.bit_width) - 1;

        /*
         * Quirk: v2 perfmon does not report fixed-purpose counters, so
         * assume at least 3 counters:
         */
        x86_pmu.num_counters_fixed      = max((int)edx.split.num_counters_fixed, 3);

        /*
         * Install the hw-cache-events table:
         */
        switch (boot_cpu_data.x86_model) {
        case 15: /* original 65 nm celeron/pentium/core2/xeon, "Merom"/"Conroe" */
        case 22: /* single-core 65 nm celeron/core2solo "Merom-L"/"Conroe-L" */
        case 23: /* current 45 nm celeron/core2/xeon "Penryn"/"Wolfdale" */
        case 29: /* six-core 45 nm xeon "Dunnington" */
                memcpy(hw_cache_event_ids, core2_hw_cache_event_ids,
                       sizeof(hw_cache_event_ids));

                pr_cont("Core2 events, ");
                break;
        default:
        case 26:
                memcpy(hw_cache_event_ids, nehalem_hw_cache_event_ids,
                       sizeof(hw_cache_event_ids));

                pr_cont("Nehalem/Corei7 events, ");
                break;
        case 28:
                memcpy(hw_cache_event_ids, atom_hw_cache_event_ids,
                       sizeof(hw_cache_event_ids));

                pr_cont("Atom events, ");
                break;
        }
        return 0;
}

static int amd_pmu_init(void)
{
        /* Performance-monitoring supported from K7 and later: */
        if (boot_cpu_data.x86 < 6)
                return -ENODEV;

        x86_pmu = amd_pmu;

        /* Events are common for all AMDs */
        memcpy(hw_cache_event_ids, amd_hw_cache_event_ids,
               sizeof(hw_cache_event_ids));

        return 0;
}

void __init init_hw_perf_counters(void)
{
        int err;

        pr_info("Performance Counters: ");

        switch (boot_cpu_data.x86_vendor) {
        case X86_VENDOR_INTEL:
                err = intel_pmu_init();
                break;
        case X86_VENDOR_AMD:
                err = amd_pmu_init();
                break;
        default:
                return;
        }
        if (err != 0) {
                pr_cont("no PMU driver, software counters only.\n");
                return;
        }

        pr_cont("%s PMU driver.\n", x86_pmu.name);

        if (x86_pmu.num_counters > X86_PMC_MAX_GENERIC) {
                WARN(1, KERN_ERR "hw perf counters %d > max(%d), clipping!",
                     x86_pmu.num_counters, X86_PMC_MAX_GENERIC);
                x86_pmu.num_counters = X86_PMC_MAX_GENERIC;
        }
        perf_counter_mask = (1 << x86_pmu.num_counters) - 1;
        perf_max_counters = x86_pmu.num_counters;

        if (x86_pmu.num_counters_fixed > X86_PMC_MAX_FIXED) {
                WARN(1, KERN_ERR "hw perf counters fixed %d > max(%d), clipping!",
                     x86_pmu.num_counters_fixed, X86_PMC_MAX_FIXED);
                x86_pmu.num_counters_fixed = X86_PMC_MAX_FIXED;
        }

        perf_counter_mask |=
                ((1LL << x86_pmu.num_counters_fixed)-1) << X86_PMC_IDX_FIXED;
        x86_pmu.intel_ctrl = perf_counter_mask;

        perf_counters_lapic_init();
        register_die_notifier(&perf_counter_nmi_notifier);

        pr_info("... version:                 %d\n",     x86_pmu.version);
        pr_info("... bit width:               %d\n",     x86_pmu.counter_bits);
        pr_info("... generic counters:        %d\n",     x86_pmu.num_counters);
        pr_info("... value mask:              %016Lx\n", x86_pmu.counter_mask);
        pr_info("... max period:              %016Lx\n", x86_pmu.max_period);
        pr_info("... fixed-purpose counters:  %d\n",     x86_pmu.num_counters_fixed);
        pr_info("... counter mask:            %016Lx\n", perf_counter_mask);
}

static inline void x86_pmu_read(struct perf_counter *counter)
{
        x86_perf_counter_update(counter, &counter->hw, counter->hw.idx);
}

static const struct pmu pmu = {
        .enable         = x86_pmu_enable,
        .disable        = x86_pmu_disable,
        .read           = x86_pmu_read,
        .unthrottle     = x86_pmu_unthrottle,
};

const struct pmu *hw_perf_counter_init(struct perf_counter *counter)
{
        int err;

        err = __hw_perf_counter_init(counter);
        if (err)
                return ERR_PTR(err);

        return &pmu;
}

/*
 * callchain support
 */

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 DEFINE_PER_CPU(struct perf_callchain_entry, irq_entry);
static DEFINE_PER_CPU(struct perf_callchain_entry, nmi_entry);
static DEFINE_PER_CPU(int, in_nmi_frame);


static void
backtrace_warning_symbol(void *data, char *msg, unsigned long symbol)
{
        /* Ignore warnings */
}

static void backtrace_warning(void *data, char *msg)
{
        /* Ignore warnings */
}

static int backtrace_stack(void *data, char *name)
{
        per_cpu(in_nmi_frame, smp_processor_id()) =
                        x86_is_stack_id(NMI_STACK, name);

        return 0;
}

static void backtrace_address(void *data, unsigned long addr, int reliable)
{
        struct perf_callchain_entry *entry = data;

        if (per_cpu(in_nmi_frame, smp_processor_id()))
                return;

        if (reliable)
                callchain_store(entry, addr);
}

static const struct stacktrace_ops backtrace_ops = {
        .warning                = backtrace_warning,
        .warning_symbol         = backtrace_warning_symbol,
        .stack                  = backtrace_stack,
        .address                = backtrace_address,
};

#include "../dumpstack.h"

static void
perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry)
{
        callchain_store(entry, PERF_CONTEXT_KERNEL);
        callchain_store(entry, regs->ip);

        dump_trace(NULL, regs, NULL, 0, &backtrace_ops, entry);
}

/*
 * best effort, GUP based copy_from_user() that assumes IRQ or NMI context
 */
static unsigned long
copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
{
        unsigned long offset, addr = (unsigned long)from;
        int type = in_nmi() ? KM_NMI : KM_IRQ0;
        unsigned long size, len = 0;
        struct page *page;
        void *map;
        int ret;

        do {
                ret = __get_user_pages_fast(addr, 1, 0, &page);
                if (!ret)
                        break;

                offset = addr & (PAGE_SIZE - 1);
                size = min(PAGE_SIZE - offset, n - len);

                map = kmap_atomic(page, type);
                memcpy(to, map+offset, size);
                kunmap_atomic(map, type);
                put_page(page);

                len  += size;
                to   += size;
                addr += size;

        } while (len < n);

        return len;
}

static int copy_stack_frame(const void __user *fp, struct stack_frame *frame)
{
        unsigned long bytes;

        bytes = copy_from_user_nmi(frame, fp, sizeof(*frame));

        return bytes == sizeof(*frame);
}

static void
perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry)
{
        struct stack_frame frame;
        const void __user *fp;

        if (!user_mode(regs))
                regs = task_pt_regs(current);

        fp = (void __user *)regs->bp;

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

        while (entry->nr < PERF_MAX_STACK_DEPTH) {
                frame.next_frame             = NULL;
                frame.return_address = 0;

                if (!copy_stack_frame(fp, &frame))
                        break;

                if ((unsigned long)fp < regs->sp)
                        break;

                callchain_store(entry, frame.return_address);
                fp = frame.next_frame;
        }
}

static void
perf_do_callchain(struct pt_regs *regs, struct perf_callchain_entry *entry)
{
        int is_user;

        if (!regs)
                return;

        is_user = user_mode(regs);

        if (!current || current->pid == 0)
                return;

        if (is_user && current->state != TASK_RUNNING)
                return;

        if (!is_user)
                perf_callchain_kernel(regs, entry);

        if (current->mm)
                perf_callchain_user(regs, entry);
}

struct perf_callchain_entry *perf_callchain(struct pt_regs *regs)
{
        struct perf_callchain_entry *entry;

        if (in_nmi())
                entry = &__get_cpu_var(nmi_entry);
        else
                entry = &__get_cpu_var(irq_entry);

        entry->nr = 0;

        perf_do_callchain(regs, entry);

        return entry;
}

void hw_perf_counter_setup_online(int cpu)
{
        init_debug_store_on_cpu(cpu);
}