kern/perfmon: new module

1 files changed, 1443 insertions, 0 deletions

diff --git a/kern/perfmon.c b/kern/perfmon.c
new file mode 100644
index 00000000..6fd319e8
--- /dev/null
+++ b/kern/perfmon.c
@@ -0,0 +1,1443 @@
+/*
+ * Copyright (c) 2014-2018 Remy Noel.
+ * Copyright (c) 2014-2018 Richard Braun.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *
+ * Locking order :
+ *
+ *             thread_runq -+
+ *                          |
+ *   event -+-> interrupts -+-> td
+ *          |
+ *          +-> pmu
+ *
+ * TODO Kernel/user mode seggregation.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#include <kern/clock.h>
+#include <kern/init.h>
+#include <kern/list.h>
+#include <kern/log.h>
+#include <kern/macros.h>
+#include <kern/percpu.h>
+#include <kern/perfmon.h>
+#include <kern/perfmon_types.h>
+#include <kern/spinlock.h>
+#include <kern/syscnt.h>
+#include <kern/thread.h>
+#include <kern/timer.h>
+#include <kern/xcall.h>
+#include <machine/boot.h>
+#include <machine/cpu.h>
+
+/*
+ * Minimum hardware counter poll interval, in milliseconds.
+ *
+ * The main purpose of polling hardware counters is to detect overflows
+ * when the driver is unable to reliably use overflow interrupts.
+ */
+#define PERFMON_MIN_POLL_INTERVAL 50
+
+/*
+ * Internal event flags.
+ */
+#define PERFMON_EF_TYPE_CPU         0x100
+#define PERFMON_EF_ATTACHED         0x200
+#define PERFMON_EF_PUBLIC_MASK      (PERFMON_EF_KERN \
+                                     | PERFMON_EF_USER \
+                                     | PERFMON_EF_RAW)
+
+/*
+ * Per-CPU performance monitoring counter.
+ *
+ * When an event is attached to a processor, the matching per-CPU PMC get
+ * referenced. When a per-CPU PMC is referenced, its underlying hardware
+ * counter is active.
+ *
+ * Interrupts and preemption must be disabled on access.
+ */
+struct perfmon_cpu_pmc {
+    unsigned int nr_refs;
+    unsigned int pmc_id;
+    unsigned int raw_event_id;
+    uint64_t raw_value;
+    uint64_t value;
+};
+
+/*
+ * Per-CPU performance monitoring unit.
+ *
+ * Per-CPU PMCs are indexed the same way as global PMCs.
+ *
+ * Interrupts and preemption must be disabled on access.
+ */
+struct perfmon_cpu_pmu {
+    struct perfmon_dev *dev;
+    unsigned int cpu;
+    struct perfmon_cpu_pmc pmcs[PERFMON_MAX_PMCS];
+    struct timer poll_timer;
+    struct syscnt sc_nr_overflows;
+};
+
+/*
+ * Performance monitoring counter.
+ *
+ * When a PMC is used, it maps a raw event to a hardware counter.
+ * A PMC is used if and only if its reference counter isn't zero.
+ */
+struct perfmon_pmc {
+    unsigned int nr_refs;
+    unsigned int pmc_id;
+    unsigned int raw_event_id;
+};
+
+/*
+ * Performance monitoring unit.
+ *
+ * There is a single system-wide logical PMU, used to globally allocate
+ * PMCs. Reserving a counter across the entire system ensures thread
+ * migration isn't hindered by performance monitoring.
+ *
+ * Locking the global PMU is only required when allocating or releasing
+ * a PMC. Once allocated, the PMC may safely be accessed without hodling
+ * the lock.
+ */
+struct perfmon_pmu {
+    struct perfmon_dev *dev;
+    struct spinlock lock;
+    struct perfmon_pmc pmcs[PERFMON_MAX_PMCS];
+};
+
+static struct perfmon_pmu perfmon_pmu;
+static struct perfmon_cpu_pmu perfmon_cpu_pmu __percpu;
+
+static struct perfmon_pmu *
+perfmon_get_pmu(void)
+{
+    return &perfmon_pmu;
+}
+
+static struct perfmon_cpu_pmu *
+perfmon_get_local_cpu_pmu(void)
+{
+    assert(!thread_preempt_enabled());
+    return cpu_local_ptr(perfmon_cpu_pmu);
+}
+
+static struct perfmon_cpu_pmu *
+perfmon_get_cpu_pmu(unsigned int cpu)
+{
+    return percpu_ptr(perfmon_cpu_pmu, cpu);
+}
+
+static void __init
+perfmon_pmc_init(struct perfmon_pmc *pmc)
+{
+    pmc->nr_refs = 0;
+}
+
+static bool
+perfmon_pmc_used(const struct perfmon_pmc *pmc)
+{
+    return pmc->nr_refs != 0;
+}
+
+static unsigned int
+perfmon_pmc_id(const struct perfmon_pmc *pmc)
+{
+    return pmc->pmc_id;
+}
+
+static unsigned int
+perfmon_pmc_raw_event_id(const struct perfmon_pmc *pmc)
+{
+    return pmc->raw_event_id;
+}
+
+static void
+perfmon_pmc_use(struct perfmon_pmc *pmc, unsigned int pmc_id,
+                unsigned int raw_event_id)
+{
+    assert(!perfmon_pmc_used(pmc));
+
+    pmc->nr_refs = 1;
+    pmc->pmc_id = pmc_id;
+    pmc->raw_event_id = raw_event_id;
+}
+
+static void
+perfmon_pmc_ref(struct perfmon_pmc *pmc)
+{
+    assert(perfmon_pmc_used(pmc));
+    pmc->nr_refs++;
+}
+
+static void
+perfmon_pmc_unref(struct perfmon_pmc *pmc)
+{
+    assert(perfmon_pmc_used(pmc));
+    pmc->nr_refs--;
+}
+
+static unsigned int
+perfmon_pmu_get_pmc_index(const struct perfmon_pmu *pmu,
+                          const struct perfmon_pmc *pmc)
+{
+    size_t pmc_index;
+
+    pmc_index = pmc - pmu->pmcs;
+    assert(pmc_index < ARRAY_SIZE(pmu->pmcs));
+    return pmc_index;
+}
+
+static struct perfmon_pmc *
+perfmon_pmu_get_pmc(struct perfmon_pmu *pmu, unsigned int index)
+{
+    assert(index < ARRAY_SIZE(pmu->pmcs));
+    return &pmu->pmcs[index];
+}
+
+static void __init
+perfmon_pmu_init(struct perfmon_pmu *pmu)
+{
+    pmu->dev = NULL;
+    spinlock_init(&pmu->lock);
+
+    for (unsigned int i = 0; i < ARRAY_SIZE(pmu->pmcs); i++) {
+        perfmon_pmc_init(perfmon_pmu_get_pmc(pmu, i));
+    }
+}
+
+static void __init
+perfmon_pmu_set_dev(struct perfmon_pmu *pmu, struct perfmon_dev *dev)
+{
+    assert(dev);
+    assert(!pmu->dev);
+    pmu->dev = dev;
+}
+
+static struct perfmon_dev *
+perfmon_pmu_get_dev(const struct perfmon_pmu *pmu)
+{
+    return pmu->dev;
+}
+
+static void
+perfmon_pmu_handle_overflow_intr(const struct perfmon_pmu *pmu)
+{
+    pmu->dev->ops->handle_overflow_intr();
+}
+
+static int
+perfmon_pmu_translate(const struct perfmon_pmu *pmu,
+                      unsigned int *raw_event_id,
+                      unsigned int event_id)
+{
+    if (!pmu->dev) {
+        return ENODEV;
+    }
+
+    return pmu->dev->ops->translate(raw_event_id, event_id);
+}
+
+static int
+perfmon_pmu_alloc_pmc_id(const struct perfmon_pmu *pmu,
+                         unsigned int *pmc_idp,
+                         unsigned int pmc_index,
+                         unsigned int raw_event_id)
+{
+    unsigned int pmc_id;
+    int error;
+
+    if (!pmu->dev) {
+        return ENODEV;
+    }
+
+    error = pmu->dev->ops->alloc(&pmc_id, pmc_index, raw_event_id);
+
+    if (error) {
+        return error;
+    }
+
+    *pmc_idp = pmc_id;
+    return 0;
+}
+
+static void
+perfmon_pmu_free_pmc_id(const struct perfmon_pmu *pmu, unsigned int pmc_id)
+{
+    assert(pmu->dev);
+    pmu->dev->ops->free(pmc_id);
+}
+
+static struct perfmon_pmc *
+perfmon_pmu_find_unused_pmc(struct perfmon_pmu *pmu)
+{
+    struct perfmon_pmc *pmc;
+
+    for (unsigned int i = 0; i < ARRAY_SIZE(pmu->pmcs); i++) {
+        pmc = perfmon_pmu_get_pmc(pmu, i);
+
+        if (!perfmon_pmc_used(pmc)) {
+            return pmc;
+        }
+    }
+
+    return NULL;
+}
+
+static int
+perfmon_pmu_alloc_pmc(struct perfmon_pmu *pmu, struct perfmon_pmc **pmcp,
+                      unsigned int raw_event_id)
+{
+    unsigned int pmc_id = 0, pmc_index;
+    struct perfmon_pmc *pmc;
+    int error;
+
+    pmc = perfmon_pmu_find_unused_pmc(pmu);
+
+    if (!pmc) {
+        return EAGAIN;
+    }
+
+    pmc_index = perfmon_pmu_get_pmc_index(pmu, pmc);
+    error = perfmon_pmu_alloc_pmc_id(pmu, &pmc_id, pmc_index, raw_event_id);
+
+    if (error) {
+        return error;
+    }
+
+    perfmon_pmc_use(pmc, pmc_id, raw_event_id);
+    *pmcp = pmc;
+    return 0;
+}
+
+static void
+perfmon_pmu_free_pmc(struct perfmon_pmu *pmu, struct perfmon_pmc *pmc)
+{
+    unsigned int pmc_id;
+
+    assert(!perfmon_pmc_used(pmc));
+    pmc_id = perfmon_pmc_id(pmc);
+    perfmon_pmu_free_pmc_id(pmu, pmc_id);
+}
+
+static struct perfmon_pmc *
+perfmon_pmu_get_pmc_by_raw_event_id(struct perfmon_pmu *pmu,
+                                    unsigned int raw_event_id)
+{
+    struct perfmon_pmc *pmc;
+
+    for (unsigned int i = 0; i < ARRAY_SIZE(pmu->pmcs); i++) {
+        pmc = perfmon_pmu_get_pmc(pmu, i);
+
+        if (!perfmon_pmc_used(pmc)) {
+            continue;
+        }
+
+        if (perfmon_pmc_raw_event_id(pmc) == raw_event_id) {
+            return pmc;
+        }
+    }
+
+    return NULL;
+}
+
+static int
+perfmon_pmu_take_pmc(struct perfmon_pmu *pmu, struct perfmon_pmc **pmcp,
+                     unsigned int raw_event_id)
+{
+    struct perfmon_pmc *pmc;
+    int error;
+
+    spinlock_lock(&pmu->lock);
+
+    pmc = perfmon_pmu_get_pmc_by_raw_event_id(pmu, raw_event_id);
+
+    if (pmc) {
+        perfmon_pmc_ref(pmc);
+        error = 0;
+    } else {
+        error = perfmon_pmu_alloc_pmc(pmu, &pmc, raw_event_id);
+
+        if (error) {
+            pmc = NULL;
+        }
+    }
+
+    spinlock_unlock(&pmu->lock);
+
+    if (error) {
+        return error;
+    }
+
+    *pmcp = pmc;
+    return 0;
+}
+
+static void
+perfmon_pmu_put_pmc(struct perfmon_pmu *pmu, struct perfmon_pmc *pmc)
+{
+    spinlock_lock(&pmu->lock);
+
+    perfmon_pmc_unref(pmc);
+
+    if (!perfmon_pmc_used(pmc)) {
+        perfmon_pmu_free_pmc(pmu, pmc);
+    }
+
+    spinlock_unlock(&pmu->lock);
+}
+
+static int
+perfmon_check_event_args(unsigned int id, unsigned int flags)
+{
+    if (!((flags & PERFMON_EF_PUBLIC_MASK) == flags)
+        || !((flags & PERFMON_EF_RAW) || (id < PERFMON_NR_GENERIC_EVENTS))
+        || !((flags & (PERFMON_EF_KERN | PERFMON_EF_USER)))) {
+        return EINVAL;
+    }
+
+    return 0;
+}
+
+int
+perfmon_event_init(struct perfmon_event *event, unsigned int id,
+                   unsigned int flags)
+{
+    int error;
+
+    error = perfmon_check_event_args(id, flags);
+
+    if (error) {
+        return error;
+    }
+
+    spinlock_init(&event->lock);
+    event->flags = flags;
+    event->id = id;
+    event->value = 0;
+    return 0;
+}
+
+static bool
+perfmon_event_type_cpu(const struct perfmon_event *event)
+{
+    return event->flags & PERFMON_EF_TYPE_CPU;
+}
+
+static void
+perfmon_event_set_type_cpu(struct perfmon_event *event)
+{
+    event->flags |= PERFMON_EF_TYPE_CPU;
+}
+
+static void
+perfmon_event_clear_type_cpu(struct perfmon_event *event)
+{
+    event->flags &= ~PERFMON_EF_TYPE_CPU;
+}
+
+static bool
+perfmon_event_attached(const struct perfmon_event *event)
+{
+    return event->flags & PERFMON_EF_ATTACHED;
+}
+
+static unsigned int
+perfmon_event_pmc_index(const struct perfmon_event *event)
+{
+    assert(perfmon_event_attached(event));
+    return event->pmc_index;
+}
+
+static void __init
+perfmon_cpu_pmc_init(struct perfmon_cpu_pmc *cpu_pmc)
+{
+    cpu_pmc->nr_refs = 0;
+}
+
+static bool
+perfmon_cpu_pmc_used(const struct perfmon_cpu_pmc *cpu_pmc)
+{
+    return cpu_pmc->nr_refs != 0;
+}
+
+static void
+perfmon_cpu_pmc_use(struct perfmon_cpu_pmc *cpu_pmc, unsigned int pmc_id,
+                    unsigned int raw_event_id, uint64_t raw_value)
+{
+    assert(!perfmon_cpu_pmc_used(cpu_pmc));
+
+    cpu_pmc->nr_refs = 1;
+    cpu_pmc->pmc_id = pmc_id;
+    cpu_pmc->raw_event_id = raw_event_id;
+    cpu_pmc->raw_value = raw_value;
+    cpu_pmc->value = 0;
+}
+
+static void
+perfmon_cpu_pmc_ref(struct perfmon_cpu_pmc *cpu_pmc)
+{
+    assert(perfmon_cpu_pmc_used(cpu_pmc));
+    cpu_pmc->nr_refs++;
+}
+
+static void
+perfmon_cpu_pmc_unref(struct perfmon_cpu_pmc *cpu_pmc)
+{
+    assert(perfmon_cpu_pmc_used(cpu_pmc));
+    cpu_pmc->nr_refs--;
+}
+
+static unsigned int
+perfmon_cpu_pmc_id(const struct perfmon_cpu_pmc *cpu_pmc)
+{
+    return cpu_pmc->pmc_id;
+}
+
+static bool
+perfmon_cpu_pmc_update(struct perfmon_cpu_pmc *cpu_pmc, uint64_t raw_value,
+                       unsigned int pmc_width)
+{
+    bool overflowed;
+    uint64_t delta;
+
+    delta = raw_value - cpu_pmc->raw_value;
+
+    if (pmc_width == 64) {
+        overflowed = false;
+    } else {
+        if (raw_value >= cpu_pmc->raw_value) {
+            overflowed = false;
+        } else {
+            overflowed = true;
+            delta += (uint64_t)1 << pmc_width;
+        }
+    }
+
+    cpu_pmc->value += delta;
+    cpu_pmc->raw_value = raw_value;
+    return overflowed;
+}
+
+static uint64_t
+perfmon_cpu_pmc_get_value(const struct perfmon_cpu_pmc *cpu_pmc)
+{
+    return cpu_pmc->value;
+}
+
+static struct perfmon_cpu_pmc *
+perfmon_cpu_pmu_get_pmc(struct perfmon_cpu_pmu *cpu_pmu, unsigned int index)
+{
+    assert(index < ARRAY_SIZE(cpu_pmu->pmcs));
+    return &cpu_pmu->pmcs[index];
+}
+
+static void
+perfmon_cpu_pmu_start(struct perfmon_cpu_pmu *cpu_pmu, unsigned int pmc_id,
+                      unsigned int raw_event_id)
+{
+    cpu_pmu->dev->ops->start(pmc_id, raw_event_id);
+}
+
+static void
+perfmon_cpu_pmu_stop(struct perfmon_cpu_pmu *cpu_pmu, unsigned int pmc_id)
+{
+    cpu_pmu->dev->ops->stop(pmc_id);
+}
+
+static uint64_t
+perfmon_cpu_pmu_read(const struct perfmon_cpu_pmu *cpu_pmu, unsigned int pmc_id)
+{
+    return cpu_pmu->dev->ops->read(pmc_id);
+}
+
+static void
+perfmon_cpu_pmu_use_pmc(struct perfmon_cpu_pmu *cpu_pmu,
+                        struct perfmon_cpu_pmc *cpu_pmc,
+                        unsigned int pmc_id,
+                        unsigned int raw_event_id)
+{
+    uint64_t raw_value;
+
+    perfmon_cpu_pmu_start(cpu_pmu, pmc_id, raw_event_id);
+    raw_value = perfmon_cpu_pmu_read(cpu_pmu, pmc_id);
+    perfmon_cpu_pmc_use(cpu_pmc, pmc_id, raw_event_id, raw_value);
+}
+
+static void
+perfmon_cpu_pmu_update_pmc(struct perfmon_cpu_pmu *cpu_pmu,
+                           struct perfmon_cpu_pmc *cpu_pmc)
+{
+    uint64_t raw_value;
+    bool overflowed;
+
+    raw_value = perfmon_cpu_pmu_read(cpu_pmu, perfmon_cpu_pmc_id(cpu_pmc));
+    overflowed = perfmon_cpu_pmc_update(cpu_pmc, raw_value,
+                                        cpu_pmu->dev->pmc_width);
+
+    if (overflowed) {
+        syscnt_inc(&cpu_pmu->sc_nr_overflows);
+    }
+}
+
+static void
+perfmon_cpu_pmu_check_overflow(void *arg)
+{
+    struct perfmon_cpu_pmu *cpu_pmu;
+    struct perfmon_cpu_pmc *cpu_pmc;
+
+    assert(!cpu_intr_enabled());
+
+    cpu_pmu = arg;
+    assert(cpu_pmu->cpu == cpu_id());
+
+    for (unsigned int i = 0; i < ARRAY_SIZE(cpu_pmu->pmcs); i++) {
+        cpu_pmc = perfmon_cpu_pmu_get_pmc(cpu_pmu, i);
+
+        if (!perfmon_cpu_pmc_used(cpu_pmc)) {
+            continue;
+        }
+
+        perfmon_cpu_pmu_update_pmc(cpu_pmu, cpu_pmc);
+    }
+}
+
+static void
+perfmon_cpu_pmu_poll(struct timer *timer)
+{
+    struct perfmon_cpu_pmu *cpu_pmu;
+
+    cpu_pmu = structof(timer, struct perfmon_cpu_pmu, poll_timer);
+    xcall_call(perfmon_cpu_pmu_check_overflow, cpu_pmu, cpu_pmu->cpu);
+    timer_schedule(timer, timer_get_time(timer) + cpu_pmu->dev->poll_interval);
+}
+
+static void __init
+perfmon_cpu_pmu_init(struct perfmon_cpu_pmu *cpu_pmu, unsigned int cpu,
+                     struct perfmon_dev *dev)
+{
+    char name[SYSCNT_NAME_SIZE];
+
+    cpu_pmu->dev = dev;
+    cpu_pmu->cpu = cpu;
+
+    for (unsigned int i = 0; i < ARRAY_SIZE(cpu_pmu->pmcs); i++) {
+        perfmon_cpu_pmc_init(perfmon_cpu_pmu_get_pmc(cpu_pmu, i));
+    }
+
+    if (dev->ops->handle_overflow_intr == NULL) {
+        assert(dev->poll_interval != 0);
+
+        /*
+         * XXX Ideally, this would be an interrupt timer instead of a high
+         * priority one, but it can't be because the handler performs
+         * cross-calls to remote processors, which requires that interrupts
+         * be enabled. This is one potential user of CPU-bound timers.
+         */
+        timer_init(&cpu_pmu->poll_timer, perfmon_cpu_pmu_poll, TIMER_HIGH_PRIO);
+        timer_schedule(&cpu_pmu->poll_timer, dev->poll_interval);
+    }
+
+    snprintf(name, sizeof(name), "perfmon_nr_overflows/%u", cpu);
+    syscnt_register(&cpu_pmu->sc_nr_overflows, name);
+}
+
+static uint64_t
+perfmon_cpu_pmu_load(struct perfmon_cpu_pmu *cpu_pmu, unsigned int pmc_index,
+                     unsigned int pmc_id, unsigned int raw_event_id)
+{
+    struct perfmon_cpu_pmc *cpu_pmc;
+
+    assert(!cpu_intr_enabled());
+
+    cpu_pmc = perfmon_cpu_pmu_get_pmc(cpu_pmu, pmc_index);
+
+    if (perfmon_cpu_pmc_used(cpu_pmc)) {
+        perfmon_cpu_pmc_ref(cpu_pmc);
+        perfmon_cpu_pmu_update_pmc(cpu_pmu, cpu_pmc);
+    } else {
+        perfmon_cpu_pmu_use_pmc(cpu_pmu, cpu_pmc, pmc_id, raw_event_id);
+    }
+
+    return perfmon_cpu_pmc_get_value(cpu_pmc);
+}
+
+static uint64_t
+perfmon_cpu_pmu_unload(struct perfmon_cpu_pmu *cpu_pmu, unsigned int pmc_index)
+{
+    struct perfmon_cpu_pmc *cpu_pmc;
+    unsigned int pmc_id;
+    uint64_t value;
+
+    assert(!cpu_intr_enabled());
+
+    cpu_pmc = perfmon_cpu_pmu_get_pmc(cpu_pmu, pmc_index);
+    pmc_id = perfmon_cpu_pmc_id(cpu_pmc);
+
+    perfmon_cpu_pmu_update_pmc(cpu_pmu, cpu_pmc);
+    value = perfmon_cpu_pmc_get_value(cpu_pmc);
+
+    perfmon_cpu_pmc_unref(cpu_pmc);
+
+    if (!perfmon_cpu_pmc_used(cpu_pmc)) {
+        perfmon_cpu_pmu_stop(cpu_pmu, pmc_id);
+    }
+
+    return value;
+}
+
+static uint64_t
+perfmon_cpu_pmu_sync(struct perfmon_cpu_pmu *cpu_pmu, unsigned int pmc_index)
+{
+    struct perfmon_cpu_pmc *cpu_pmc;
+
+    assert(!cpu_intr_enabled());
+
+    cpu_pmc = perfmon_cpu_pmu_get_pmc(cpu_pmu, pmc_index);
+    perfmon_cpu_pmu_update_pmc(cpu_pmu, cpu_pmc);
+    return perfmon_cpu_pmc_get_value(cpu_pmc);
+}
+
+static void
+perfmon_td_pmc_init(struct perfmon_td_pmc *td_pmc)
+{
+    td_pmc->nr_refs = 0;
+    td_pmc->loaded = false;
+    td_pmc->value = 0;
+}
+
+static bool
+perfmon_td_pmc_used(const struct perfmon_td_pmc *td_pmc)
+{
+    return td_pmc->nr_refs != 0;
+}
+
+static void
+perfmon_td_pmc_use(struct perfmon_td_pmc *td_pmc, unsigned int pmc_id,
+                   unsigned int raw_event_id)
+{
+    assert(!perfmon_td_pmc_used(td_pmc));
+
+    td_pmc->nr_refs = 1;
+    td_pmc->loaded = false;
+    td_pmc->pmc_id = pmc_id;
+    td_pmc->raw_event_id = raw_event_id;
+    td_pmc->value = 0;
+}
+
+static unsigned int
+perfmon_td_pmc_id(const struct perfmon_td_pmc *td_pmc)
+{
+    return td_pmc->pmc_id;
+}
+
+static unsigned int
+perfmon_td_pmc_raw_event_id(const struct perfmon_td_pmc *td_pmc)
+{
+    return td_pmc->raw_event_id;
+}
+
+static void
+perfmon_td_pmc_ref(struct perfmon_td_pmc *td_pmc)
+{
+    assert(perfmon_td_pmc_used(td_pmc));
+    td_pmc->nr_refs++;
+}
+
+static void
+perfmon_td_pmc_unref(struct perfmon_td_pmc *td_pmc)
+{
+    assert(perfmon_td_pmc_used(td_pmc));
+    td_pmc->nr_refs--;
+}
+
+static bool
+perfmon_td_pmc_loaded(const struct perfmon_td_pmc *td_pmc)
+{
+    return td_pmc->loaded;
+}
+
+static void
+perfmon_td_pmc_load(struct perfmon_td_pmc *td_pmc, uint64_t cpu_pmc_value)
+{
+    assert(!perfmon_td_pmc_loaded(td_pmc));
+
+    td_pmc->cpu_pmc_value = cpu_pmc_value;
+    td_pmc->loaded = true;
+}
+
+static void
+perfmon_td_pmc_update(struct perfmon_td_pmc *td_pmc, uint64_t cpu_pmc_value)
+{
+    uint64_t delta;
+
+    assert(perfmon_td_pmc_loaded(td_pmc));
+
+    delta = cpu_pmc_value - td_pmc->cpu_pmc_value;
+    td_pmc->cpu_pmc_value = cpu_pmc_value;
+    td_pmc->value += delta;
+}
+
+static void
+perfmon_td_pmc_unload(struct perfmon_td_pmc *td_pmc, uint64_t cpu_pmc_value)
+{
+    perfmon_td_pmc_update(td_pmc, cpu_pmc_value);
+    td_pmc->loaded = false;
+}
+
+static uint64_t
+perfmon_td_pmc_read(const struct perfmon_td_pmc *td_pmc)
+{
+    return td_pmc->value;
+}
+
+static unsigned int
+perfmon_td_get_pmc_index(const struct perfmon_td *td,
+                         const struct perfmon_td_pmc *td_pmc)
+{
+    size_t pmc_index;
+
+    pmc_index = td_pmc - td->pmcs;
+    assert(pmc_index < ARRAY_SIZE(td->pmcs));
+    return pmc_index;
+}
+
+static struct perfmon_td_pmc *
+perfmon_td_get_pmc(struct perfmon_td *td, unsigned int index)
+{
+    assert(index < ARRAY_SIZE(td->pmcs));
+    return &td->pmcs[index];
+}
+
+void
+perfmon_td_init(struct perfmon_td *td)
+{
+    spinlock_init(&td->lock);
+
+    for (unsigned int i = 0; i < ARRAY_SIZE(td->pmcs); i++) {
+        perfmon_td_pmc_init(perfmon_td_get_pmc(td, i));
+    }
+}
+
+static void
+perfmon_td_load_pmc(struct perfmon_td *td, struct perfmon_td_pmc *td_pmc)
+{
+    unsigned int pmc_index, pmc_id, raw_event_id;
+    struct perfmon_cpu_pmu *cpu_pmu;
+    uint64_t cpu_pmc_value;
+
+    cpu_pmu = perfmon_get_local_cpu_pmu();
+    pmc_index = perfmon_td_get_pmc_index(td, td_pmc);
+    pmc_id = perfmon_td_pmc_id(td_pmc);
+    raw_event_id = perfmon_td_pmc_raw_event_id(td_pmc);
+    cpu_pmc_value = perfmon_cpu_pmu_load(cpu_pmu, pmc_index,
+                                         pmc_id, raw_event_id);
+    perfmon_td_pmc_load(td_pmc, cpu_pmc_value);
+}
+
+static void
+perfmon_td_unload_pmc(struct perfmon_td *td, struct perfmon_td_pmc *td_pmc)
+{
+    struct perfmon_cpu_pmu *cpu_pmu;
+    unsigned int pmc_index;
+    uint64_t cpu_pmc_value;
+
+    cpu_pmu = perfmon_get_local_cpu_pmu();
+    pmc_index = perfmon_td_get_pmc_index(td, td_pmc);
+    cpu_pmc_value = perfmon_cpu_pmu_unload(cpu_pmu, pmc_index);
+    perfmon_td_pmc_unload(td_pmc, cpu_pmc_value);
+}
+
+static void
+perfmon_td_update_pmc(struct perfmon_td *td, struct perfmon_td_pmc *td_pmc)
+{
+    struct perfmon_cpu_pmu *cpu_pmu;
+    unsigned int pmc_index;
+    uint64_t cpu_pmc_value;
+
+    cpu_pmu = perfmon_get_local_cpu_pmu();
+    pmc_index = perfmon_td_get_pmc_index(td, td_pmc);
+    cpu_pmc_value = perfmon_cpu_pmu_sync(cpu_pmu, pmc_index);
+    perfmon_td_pmc_update(td_pmc, cpu_pmc_value);
+}
+
+void
+perfmon_td_load(struct perfmon_td *td)
+{
+    unsigned int pmc_index, pmc_id, raw_event_id;
+    struct perfmon_cpu_pmu *cpu_pmu;
+    struct perfmon_td_pmc *td_pmc;
+    uint64_t cpu_pmc_value;
+
+    assert(!cpu_intr_enabled());
+    assert(!thread_preempt_enabled());
+
+    cpu_pmu = perfmon_get_local_cpu_pmu();
+
+    spinlock_lock(&td->lock);
+
+    for (unsigned int i = 0; i < ARRAY_SIZE(td->pmcs); i++) {
+        td_pmc = perfmon_td_get_pmc(td, i);
+
+        if (!perfmon_td_pmc_used(td_pmc) || perfmon_td_pmc_loaded(td_pmc)) {
+            continue;
+        }
+
+        pmc_index = perfmon_td_get_pmc_index(td, td_pmc);
+        pmc_id = perfmon_td_pmc_id(td_pmc);
+        raw_event_id = perfmon_td_pmc_raw_event_id(td_pmc);
+        cpu_pmc_value = perfmon_cpu_pmu_load(cpu_pmu, pmc_index,
+                                             pmc_id, raw_event_id);
+        perfmon_td_pmc_load(td_pmc, cpu_pmc_value);
+    }
+
+    spinlock_unlock(&td->lock);
+}
+
+void
+perfmon_td_unload(struct perfmon_td *td)
+{
+    struct perfmon_cpu_pmu *cpu_pmu;
+    struct perfmon_td_pmc *td_pmc;
+    unsigned int pmc_index;
+    uint64_t cpu_pmc_value;
+
+    assert(!cpu_intr_enabled());
+    assert(!thread_preempt_enabled());
+
+    cpu_pmu = perfmon_get_local_cpu_pmu();
+
+    spinlock_lock(&td->lock);
+
+    for (unsigned int i = 0; i < ARRAY_SIZE(td->pmcs); i++) {
+        td_pmc = perfmon_td_get_pmc(td, i);
+
+        if (!perfmon_td_pmc_loaded(td_pmc)) {
+            continue;
+        }
+
+        pmc_index = perfmon_td_get_pmc_index(td, td_pmc);
+        cpu_pmc_value = perfmon_cpu_pmu_unload(cpu_pmu, pmc_index);
+        perfmon_td_pmc_unload(td_pmc, cpu_pmc_value);
+    }
+
+    spinlock_unlock(&td->lock);
+}
+
+static void
+perfmon_event_load(struct perfmon_event *event, uint64_t pmc_value)
+{
+    event->pmc_value = pmc_value;
+}
+
+static void
+perfmon_event_update(struct perfmon_event *event, uint64_t pmc_value)
+{
+    uint64_t delta;
+
+    delta = pmc_value - event->pmc_value;
+    event->value += delta;
+    event->pmc_value = pmc_value;
+}
+
+static void
+perfmon_event_load_cpu_remote(void *arg)
+{
+    struct perfmon_event *event;
+    struct perfmon_cpu_pmu *cpu_pmu;
+    const struct perfmon_pmc *pmc;
+    struct perfmon_pmu *pmu;
+    unsigned int pmc_index;
+    uint64_t cpu_pmc_value;
+
+    event = arg;
+    cpu_pmu = perfmon_get_local_cpu_pmu();
+    pmu = perfmon_get_pmu();
+    pmc_index = perfmon_event_pmc_index(event);
+    pmc = perfmon_pmu_get_pmc(pmu, pmc_index);
+    cpu_pmc_value = perfmon_cpu_pmu_load(cpu_pmu, pmc_index,
+                                         perfmon_pmc_id(pmc),
+                                         perfmon_pmc_raw_event_id(pmc));
+    perfmon_event_load(event, cpu_pmc_value);
+}
+
+static void
+perfmon_event_load_cpu(struct perfmon_event *event, unsigned int cpu)
+{
+    perfmon_event_set_type_cpu(event);
+    event->cpu = cpu;
+    xcall_call(perfmon_event_load_cpu_remote, event, cpu);
+}
+
+static void
+perfmon_event_load_thread_remote(void *arg)
+{
+    struct perfmon_event *event;
+    struct perfmon_td_pmc *td_pmc;
+    struct perfmon_td *td;
+    unsigned int pmc_index;
+    uint64_t td_pmc_value;
+
+    event = arg;
+    pmc_index = perfmon_event_pmc_index(event);
+    td = thread_get_perfmon_td(event->thread);
+    td_pmc = perfmon_td_get_pmc(td, pmc_index);
+
+    spinlock_lock(&td->lock);
+
+    if (thread_self() == event->thread) {
+
+        if (perfmon_td_pmc_loaded(td_pmc)) {
+            perfmon_td_update_pmc(td, td_pmc);
+        } else {
+            perfmon_td_load_pmc(td, td_pmc);
+        }
+    }
+
+    td_pmc_value = perfmon_td_pmc_read(td_pmc);
+
+    spinlock_unlock(&td->lock);
+
+    perfmon_event_load(event, td_pmc_value);
+}
+
+static void
+perfmon_event_load_thread(struct perfmon_event *event, struct thread *thread)
+{
+    struct perfmon_td_pmc *td_pmc;
+    struct perfmon_td *td;
+    struct perfmon_pmu *pmu;
+    const struct perfmon_pmc *pmc;
+    unsigned int pmc_index;
+    unsigned long flags;
+
+    pmu = perfmon_get_pmu();
+
+    thread_ref(thread);
+    event->thread = thread;
+
+    pmc_index = perfmon_event_pmc_index(event);
+    pmc = perfmon_pmu_get_pmc(pmu, pmc_index);
+    td = thread_get_perfmon_td(thread);
+    td_pmc = perfmon_td_get_pmc(td, pmc_index);
+
+    spinlock_lock_intr_save(&td->lock, &flags);
+
+    if (perfmon_td_pmc_used(td_pmc)) {
+        perfmon_td_pmc_ref(td_pmc);
+    } else {
+        perfmon_td_pmc_use(td_pmc, perfmon_pmc_id(pmc),
+                           perfmon_pmc_raw_event_id(pmc));
+    }
+
+    spinlock_unlock_intr_restore(&td->lock, flags);
+
+    xcall_call(perfmon_event_load_thread_remote, event, thread_cpu(thread));
+}
+
+static void
+perfmon_event_unload_cpu_remote(void *arg)
+{
+    struct perfmon_event *event;
+    struct perfmon_cpu_pmu *cpu_pmu;
+    unsigned int pmc_index;
+    uint64_t cpu_pmc_value;
+
+    event = arg;
+    cpu_pmu = perfmon_get_local_cpu_pmu();
+    pmc_index = perfmon_event_pmc_index(event);
+    cpu_pmc_value = perfmon_cpu_pmu_unload(cpu_pmu, pmc_index);
+    perfmon_event_update(event, cpu_pmc_value);
+}
+
+static void
+perfmon_event_unload_cpu(struct perfmon_event *event)
+{
+    xcall_call(perfmon_event_unload_cpu_remote, event, event->cpu);
+    perfmon_event_clear_type_cpu(event);
+}
+
+static void
+perfmon_event_unload_thread_remote(void *arg)
+{
+    struct perfmon_event *event;
+    struct perfmon_td_pmc *td_pmc;
+    struct perfmon_td *td;
+    unsigned int pmc_index;
+    uint64_t td_pmc_value;
+
+    event = arg;
+    pmc_index = perfmon_event_pmc_index(event);
+    td = thread_get_perfmon_td(event->thread);
+    td_pmc = perfmon_td_get_pmc(td, pmc_index);
+
+    spinlock_lock(&td->lock);
+
+    if ((thread_self() == event->thread) && perfmon_td_pmc_loaded(td_pmc)) {
+        if (perfmon_td_pmc_used(td_pmc)) {
+            perfmon_td_update_pmc(td, td_pmc);
+        } else {
+            perfmon_td_unload_pmc(td, td_pmc);
+        }
+    }
+
+    td_pmc_value = perfmon_td_pmc_read(td_pmc);
+
+    spinlock_unlock(&td->lock);
+
+    perfmon_event_update(event, td_pmc_value);
+}
+
+static void
+perfmon_event_unload_thread(struct perfmon_event *event)
+{
+    struct perfmon_td_pmc *td_pmc;
+    struct perfmon_td *td;
+    unsigned int pmc_index;
+    unsigned long flags;
+
+    pmc_index = perfmon_event_pmc_index(event);
+    td = thread_get_perfmon_td(event->thread);
+    td_pmc = perfmon_td_get_pmc(td, pmc_index);
+
+    spinlock_lock_intr_save(&td->lock, &flags);
+    perfmon_td_pmc_unref(td_pmc);
+    spinlock_unlock_intr_restore(&td->lock, flags);
+
+    xcall_call(perfmon_event_unload_thread_remote, event,
+               thread_cpu(event->thread));
+
+    thread_unref(event->thread);
+    event->thread = NULL;
+}
+
+static void
+perfmon_event_sync_cpu_remote(void *arg)
+{
+    struct perfmon_event *event;
+    struct perfmon_cpu_pmu *cpu_pmu;
+    unsigned int pmc_index;
+    uint64_t cpu_pmc_value;
+
+    event = arg;
+    cpu_pmu = perfmon_get_local_cpu_pmu();
+    pmc_index = perfmon_event_pmc_index(event);
+    cpu_pmc_value = perfmon_cpu_pmu_sync(cpu_pmu, pmc_index);
+    perfmon_event_update(event, cpu_pmc_value);
+}
+
+static void
+perfmon_event_sync_cpu(struct perfmon_event *event)
+{
+    xcall_call(perfmon_event_sync_cpu_remote, event, event->cpu);
+}
+
+static void
+perfmon_event_sync_thread_remote(void *arg)
+{
+    struct perfmon_event *event;
+    struct perfmon_td_pmc *td_pmc;
+    struct perfmon_td *td;
+    unsigned int pmc_index;
+    uint64_t td_pmc_value;
+
+    event = arg;
+    pmc_index = perfmon_event_pmc_index(event);
+    td = thread_get_perfmon_td(event->thread);
+    td_pmc = perfmon_td_get_pmc(td, pmc_index);
+
+    spinlock_lock(&td->lock);
+
+    if (thread_self() == event->thread) {
+        perfmon_td_update_pmc(td, td_pmc);
+    }
+
+    td_pmc_value = perfmon_td_pmc_read(td_pmc);
+
+    spinlock_unlock(&td->lock);
+
+    perfmon_event_update(event, td_pmc_value);
+}
+
+static void
+perfmon_event_sync_thread(struct perfmon_event *event)
+{
+    xcall_call(perfmon_event_sync_thread_remote, event,
+               thread_cpu(event->thread));
+}
+
+static int
+perfmon_event_attach_pmu(struct perfmon_event *event)
+{
+    unsigned int raw_event_id = 0;
+    struct perfmon_pmu *pmu;
+    struct perfmon_pmc *pmc;
+    int error;
+
+    pmu = perfmon_get_pmu();
+
+    if (!(event->flags & PERFMON_EF_RAW)) {
+        error = perfmon_pmu_translate(pmu, &raw_event_id, event->id);
+
+        if (error) {
+            return error;
+        }
+    }
+
+    error = perfmon_pmu_take_pmc(pmu, &pmc, raw_event_id);
+
+    if (error) {
+        return error;
+    }
+
+    event->pmc_index = perfmon_pmu_get_pmc_index(pmu, pmc);
+    event->flags |= PERFMON_EF_ATTACHED;
+    event->value = 0;
+    return 0;
+}
+
+static void
+perfmon_event_detach_pmu(struct perfmon_event *event)
+{
+    struct perfmon_pmu *pmu;
+    struct perfmon_pmc *pmc;
+
+    pmu = perfmon_get_pmu();
+    pmc = perfmon_pmu_get_pmc(pmu, perfmon_event_pmc_index(event));
+    perfmon_pmu_put_pmc(pmu, pmc);
+    event->flags &= ~PERFMON_EF_ATTACHED;
+}
+
+int
+perfmon_event_attach(struct perfmon_event *event, struct thread *thread)
+{
+    int error;
+
+    spinlock_lock(&event->lock);
+
+    if (perfmon_event_attached(event)) {
+        error = EINVAL;
+        goto error;
+    }
+
+    error = perfmon_event_attach_pmu(event);
+
+    if (error) {
+        goto error;
+    }
+
+    perfmon_event_load_thread(event, thread);
+
+    spinlock_unlock(&event->lock);
+
+    return 0;
+
+error:
+    spinlock_unlock(&event->lock);
+
+    return error;
+}
+
+int
+perfmon_event_attach_cpu(struct perfmon_event *event, unsigned int cpu)
+{
+    int error;
+
+    if (cpu >= cpu_count()) {
+        return EINVAL;
+    }
+
+    spinlock_lock(&event->lock);
+
+    if (perfmon_event_attached(event)) {
+        error = EINVAL;
+        goto out;
+    }
+
+    error = perfmon_event_attach_pmu(event);
+
+    if (error) {
+        goto out;
+    }
+
+    perfmon_event_load_cpu(event, cpu);
+    error = 0;
+
+out:
+    spinlock_unlock(&event->lock);
+
+    return error;
+}
+
+int
+perfmon_event_detach(struct perfmon_event *event)
+{
+    int error;
+
+    spinlock_lock(&event->lock);
+
+    if (!perfmon_event_attached(event)) {
+        error = EINVAL;
+        goto out;
+    }
+
+    if (perfmon_event_type_cpu(event)) {
+        perfmon_event_unload_cpu(event);
+    } else {
+        perfmon_event_unload_thread(event);
+    }
+
+    perfmon_event_detach_pmu(event);
+    error = 0;
+
+out:
+    spinlock_unlock(&event->lock);
+
+    return error;
+}
+
+uint64_t
+perfmon_event_read(struct perfmon_event *event)
+{
+    uint64_t value;
+
+    spinlock_lock(&event->lock);
+
+    if (perfmon_event_attached(event)) {
+        if (perfmon_event_type_cpu(event)) {
+            perfmon_event_sync_cpu(event);
+        } else {
+            perfmon_event_sync_thread(event);
+        }
+    }
+
+    value = event->value;
+
+    spinlock_unlock(&event->lock);
+
+    return value;
+}
+
+static uint64_t __init
+perfmon_compute_poll_interval(uint64_t pmc_width)
+{
+    uint64_t cycles, time;
+
+    if (pmc_width == 64) {
+        cycles = (uint64_t)-1;
+    } else {
+        cycles = (uint64_t)1 << pmc_width;
+    }
+
+    /*
+     * Assume an unrealistically high upper bound on the number of
+     * events per cycle to otbain a comfortable margin of safety.
+     */
+    cycles /= 100;
+    time = cycles / (cpu_get_freq() / 1000);
+
+    if (time < PERFMON_MIN_POLL_INTERVAL) {
+        log_warning("perfmon: invalid poll interval %llu, forced to %llu",
+                    (unsigned long long)time,
+                    (unsigned long long)PERFMON_MIN_POLL_INTERVAL);
+        time = PERFMON_MIN_POLL_INTERVAL;
+    }
+
+    return clock_ticks_from_ms(time);
+}
+
+void __init
+perfmon_register(struct perfmon_dev *dev)
+{
+    const struct perfmon_dev_ops *ops;
+
+    ops = dev->ops;
+    assert(ops->translate && ops->alloc && ops->free
+           && ops->start && ops->stop && ops->read);
+    assert(dev->pmc_width <= 64);
+
+    if ((dev->ops->handle_overflow_intr == NULL) && (dev->poll_interval == 0)) {
+        dev->poll_interval = perfmon_compute_poll_interval(dev->pmc_width);
+    }
+
+    perfmon_pmu_set_dev(perfmon_get_pmu(), dev);
+}
+
+void
+perfmon_overflow_intr(void)
+{
+    perfmon_pmu_handle_overflow_intr(perfmon_get_pmu());
+}
+
+void
+perfmon_report_overflow(unsigned int pmc_index)
+{
+    struct perfmon_cpu_pmu *cpu_pmu;
+    struct perfmon_cpu_pmc *cpu_pmc;
+
+    assert(!cpu_intr_enabled());
+    assert(!thread_preempt_enabled());
+
+    cpu_pmu = perfmon_get_local_cpu_pmu();
+    cpu_pmc = perfmon_cpu_pmu_get_pmc(cpu_pmu, pmc_index);
+    perfmon_cpu_pmu_update_pmc(cpu_pmu, cpu_pmc);
+}
+
+static int __init
+perfmon_bootstrap(void)
+{
+    perfmon_pmu_init(perfmon_get_pmu());
+    return 0;
+}
+
+INIT_OP_DEFINE(perfmon_bootstrap,
+               INIT_OP_DEP(log_setup, true),
+               INIT_OP_DEP(spinlock_setup, true));
+
+static int __init
+perfmon_setup(void)
+{
+    struct perfmon_dev *dev;
+
+    dev = perfmon_pmu_get_dev(perfmon_get_pmu());
+
+    if (!dev) {
+        return ENODEV;
+    }
+
+    for (unsigned int cpu = 0; cpu < cpu_count(); cpu++) {
+        perfmon_cpu_pmu_init(perfmon_get_cpu_pmu(cpu), cpu, dev);
+    }
+
+    return 0;
+}
+
+INIT_OP_DEFINE(perfmon_setup,
+               INIT_OP_DEP(boot_setup_pmu, true),
+               INIT_OP_DEP(cpu_mp_probe, true),
+               INIT_OP_DEP(cpu_setup, true),
+               INIT_OP_DEP(percpu_setup, true),
+               INIT_OP_DEP(perfmon_bootstrap, true),
+               INIT_OP_DEP(spinlock_setup, true),
+               INIT_OP_DEP(syscnt_setup, true));