linux/arch/sh/kernel/perf_event.c

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/*
* Performance event support framework for SuperH hardware counters.
*
* Copyright (C) 2009 Paul Mundt
*
* Heavily based on the x86 and PowerPC implementations.
*
* x86:
* 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>
*
* ppc:
* Copyright 2008-2009 Paul Mackerras, IBM Corporation.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/perf_event.h>
#include <linux/export.h>
#include <asm/processor.h>
struct cpu_hw_events {
struct perf_event *events[MAX_HWEVENTS];
unsigned long used_mask[BITS_TO_LONGS(MAX_HWEVENTS)];
unsigned long active_mask[BITS_TO_LONGS(MAX_HWEVENTS)];
};
DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);
static struct sh_pmu *sh_pmu __read_mostly;
/* Number of perf_events counting hardware events */
static atomic_t num_events;
/* Used to avoid races in calling reserve/release_pmc_hardware */
static DEFINE_MUTEX(pmc_reserve_mutex);
/*
* Stub these out for now, do something more profound later.
*/
int reserve_pmc_hardware(void)
{
return 0;
}
void release_pmc_hardware(void)
{
}
static inline int sh_pmu_initialized(void)
{
return !!sh_pmu;
}
const char *perf_pmu_name(void)
{
if (!sh_pmu)
return NULL;
return sh_pmu->name;
}
EXPORT_SYMBOL_GPL(perf_pmu_name);
int perf_num_counters(void)
{
if (!sh_pmu)
return 0;
return sh_pmu->num_events;
}
EXPORT_SYMBOL_GPL(perf_num_counters);
/*
* Release the PMU if this is the last perf_event.
*/
static void hw_perf_event_destroy(struct perf_event *event)
{
if (!atomic_add_unless(&num_events, -1, 1)) {
mutex_lock(&pmc_reserve_mutex);
if (atomic_dec_return(&num_events) == 0)
release_pmc_hardware();
mutex_unlock(&pmc_reserve_mutex);
}
}
static int hw_perf_cache_event(int config, int *evp)
{
unsigned long type, op, result;
int ev;
if (!sh_pmu->cache_events)
return -EINVAL;
/* unpack config */
type = config & 0xff;
op = (config >> 8) & 0xff;
result = (config >> 16) & 0xff;
if (type >= PERF_COUNT_HW_CACHE_MAX ||
op >= PERF_COUNT_HW_CACHE_OP_MAX ||
result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
return -EINVAL;
ev = (*sh_pmu->cache_events)[type][op][result];
if (ev == 0)
return -EOPNOTSUPP;
if (ev == -1)
return -EINVAL;
*evp = ev;
return 0;
}
static int __hw_perf_event_init(struct perf_event *event)
{
struct perf_event_attr *attr = &event->attr;
struct hw_perf_event *hwc = &event->hw;
int config = -1;
int err;
if (!sh_pmu_initialized())
return -ENODEV;
/*
* All of the on-chip counters are "limited", in that they have
* no interrupts, and are therefore unable to do sampling without
* further work and timer assistance.
*/
if (hwc->sample_period)
return -EINVAL;
/*
* See if we need to reserve the counter.
*
* If no events are currently in use, then we have to take a
* mutex to ensure that we don't race with another task doing
* reserve_pmc_hardware or release_pmc_hardware.
*/
err = 0;
if (!atomic_inc_not_zero(&num_events)) {
mutex_lock(&pmc_reserve_mutex);
if (atomic_read(&num_events) == 0 &&
reserve_pmc_hardware())
err = -EBUSY;
else
atomic_inc(&num_events);
mutex_unlock(&pmc_reserve_mutex);
}
if (err)
return err;
event->destroy = hw_perf_event_destroy;
switch (attr->type) {
case PERF_TYPE_RAW:
config = attr->config & sh_pmu->raw_event_mask;
break;
case PERF_TYPE_HW_CACHE:
err = hw_perf_cache_event(attr->config, &config);
if (err)
return err;
break;
case PERF_TYPE_HARDWARE:
if (attr->config >= sh_pmu->max_events)
return -EINVAL;
config = sh_pmu->event_map(attr->config);
break;
}
if (config == -1)
return -EINVAL;
hwc->config |= config;
return 0;
}
static void sh_perf_event_update(struct perf_event *event,
struct hw_perf_event *hwc, int idx)
{
u64 prev_raw_count, new_raw_count;
s64 delta;
int shift = 0;
/*
* Depending on the counter configuration, they may or may not
* be chained, in which case the previous counter value can be
* updated underneath us if the lower-half overflows.
*
* 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.
*
* As there is no interrupt associated with the overflow events,
* this is the simplest approach for maintaining consistency.
*/
again:
prev_raw_count = local64_read(&hwc->prev_count);
new_raw_count = sh_pmu->read(idx);
if (local64_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;
local64_add(delta, &event->count);
}
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static void sh_pmu_stop(struct perf_event *event, int flags)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
struct hw_perf_event *hwc = &event->hw;
int idx = hwc->idx;
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if (!(event->hw.state & PERF_HES_STOPPED)) {
sh_pmu->disable(hwc, idx);
cpuc->events[idx] = NULL;
event->hw.state |= PERF_HES_STOPPED;
}
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if ((flags & PERF_EF_UPDATE) && !(event->hw.state & PERF_HES_UPTODATE)) {
sh_perf_event_update(event, &event->hw, idx);
event->hw.state |= PERF_HES_UPTODATE;
}
}
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static void sh_pmu_start(struct perf_event *event, int flags)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
struct hw_perf_event *hwc = &event->hw;
int idx = hwc->idx;
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if (WARN_ON_ONCE(idx == -1))
return;
if (flags & PERF_EF_RELOAD)
WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
cpuc->events[idx] = event;
event->hw.state = 0;
sh_pmu->enable(hwc, idx);
}
static void sh_pmu_del(struct perf_event *event, int flags)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
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sh_pmu_stop(event, PERF_EF_UPDATE);
__clear_bit(event->hw.idx, cpuc->used_mask);
perf_event_update_userpage(event);
}
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static int sh_pmu_add(struct perf_event *event, int flags)
{
struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
struct hw_perf_event *hwc = &event->hw;
int idx = hwc->idx;
int ret = -EAGAIN;
perf_pmu_disable(event->pmu);
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if (__test_and_set_bit(idx, cpuc->used_mask)) {
idx = find_first_zero_bit(cpuc->used_mask, sh_pmu->num_events);
if (idx == sh_pmu->num_events)
goto out;
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__set_bit(idx, cpuc->used_mask);
hwc->idx = idx;
}
sh_pmu->disable(hwc, idx);
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event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
if (flags & PERF_EF_START)
sh_pmu_start(event, PERF_EF_RELOAD);
perf_event_update_userpage(event);
ret = 0;
out:
perf_pmu_enable(event->pmu);
return ret;
}
static void sh_pmu_read(struct perf_event *event)
{
sh_perf_event_update(event, &event->hw, event->hw.idx);
}
static int sh_pmu_event_init(struct perf_event *event)
{
int err;
/* does not support taken branch sampling */
if (has_branch_stack(event))
return -EOPNOTSUPP;
switch (event->attr.type) {
case PERF_TYPE_RAW:
case PERF_TYPE_HW_CACHE:
case PERF_TYPE_HARDWARE:
err = __hw_perf_event_init(event);
break;
default:
return -ENOENT;
}
if (unlikely(err)) {
if (event->destroy)
event->destroy(event);
}
return err;
}
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static void sh_pmu_enable(struct pmu *pmu)
{
if (!sh_pmu_initialized())
return;
sh_pmu->enable_all();
}
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static void sh_pmu_disable(struct pmu *pmu)
{
if (!sh_pmu_initialized())
return;
sh_pmu->disable_all();
}
static struct pmu pmu = {
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.pmu_enable = sh_pmu_enable,
.pmu_disable = sh_pmu_disable,
.event_init = sh_pmu_event_init,
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.add = sh_pmu_add,
.del = sh_pmu_del,
.start = sh_pmu_start,
.stop = sh_pmu_stop,
.read = sh_pmu_read,
};
static void sh_pmu_setup(int cpu)
{
struct cpu_hw_events *cpuhw = &per_cpu(cpu_hw_events, cpu);
memset(cpuhw, 0, sizeof(struct cpu_hw_events));
}
static int __cpuinit
sh_pmu_notifier(struct notifier_block *self, unsigned long action, void *hcpu)
{
unsigned int cpu = (long)hcpu;
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_UP_PREPARE:
sh_pmu_setup(cpu);
break;
default:
break;
}
return NOTIFY_OK;
}
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int __cpuinit register_sh_pmu(struct sh_pmu *_pmu)
{
if (sh_pmu)
return -EBUSY;
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sh_pmu = _pmu;
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pr_info("Performance Events: %s support registered\n", _pmu->name);
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WARN_ON(_pmu->num_events > MAX_HWEVENTS);
perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW);
perf_cpu_notifier(sh_pmu_notifier);
return 0;
}