arch/sh/kernel/perf_event.c

   1 /*
   2  * Performance event support framework for SuperH hardware counters.
   3  *
   4  *  Copyright (C) 2009  Paul Mundt
   5  *
   6  * Heavily based on the x86 and PowerPC implementations.
   7  *
   8  * x86:
   9  *  Copyright (C) 2008 Thomas Gleixner <tglx@linutronix.de>
  10  *  Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar
  11  *  Copyright (C) 2009 Jaswinder Singh Rajput
  12  *  Copyright (C) 2009 Advanced Micro Devices, Inc., Robert Richter
  13  *  Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
  14  *  Copyright (C) 2009 Intel Corporation, <markus.t.metzger@intel.com>
  15  *
  16  * ppc:
  17  *  Copyright 2008-2009 Paul Mackerras, IBM Corporation.
  18  *
  19  * This file is subject to the terms and conditions of the GNU General Public
  20  * License.  See the file "COPYING" in the main directory of this archive
  21  * for more details.
  22  */
  23 #include <linux/kernel.h>
  24 #include <linux/init.h>
  25 #include <linux/io.h>
  26 #include <linux/irq.h>
  27 #include <linux/perf_event.h>
  28 #include <linux/export.h>
  29 #include <asm/processor.h>
  30
  31 struct cpu_hw_events {
  32         struct perf_event       *events[MAX_HWEVENTS];
  33         unsigned long           used_mask[BITS_TO_LONGS(MAX_HWEVENTS)];
  34         unsigned long           active_mask[BITS_TO_LONGS(MAX_HWEVENTS)];
  35 };
  36
  37 DEFINE_PER_CPU(struct cpu_hw_events, cpu_hw_events);
  38
  39 static struct sh_pmu *sh_pmu __read_mostly;
  40
  41 /* Number of perf_events counting hardware events */
  42 static atomic_t num_events;
  43 /* Used to avoid races in calling reserve/release_pmc_hardware */
  44 static DEFINE_MUTEX(pmc_reserve_mutex);
  45
  46 /*
  47  * Stub these out for now, do something more profound later.
  48  */
  49 int reserve_pmc_hardware(void)
  50 {
  51         return 0;
  52 }
  53
  54 void release_pmc_hardware(void)
  55 {
  56 }
  57
  58 static inline int sh_pmu_initialized(void)
  59 {
  60         return !!sh_pmu;
  61 }
  62
  63 const char *perf_pmu_name(void)
  64 {
  65         if (!sh_pmu)
  66                 return NULL;
  67
  68         return sh_pmu->name;
  69 }
  70 EXPORT_SYMBOL_GPL(perf_pmu_name);
  71
  72 int perf_num_counters(void)
  73 {
  74         if (!sh_pmu)
  75                 return 0;
  76
  77         return sh_pmu->num_events;
  78 }
  79 EXPORT_SYMBOL_GPL(perf_num_counters);
  80
  81 /*
  82  * Release the PMU if this is the last perf_event.
  83  */
  84 static void hw_perf_event_destroy(struct perf_event *event)
  85 {
  86         if (!atomic_add_unless(&num_events, -1, 1)) {
  87                 mutex_lock(&pmc_reserve_mutex);
  88                 if (atomic_dec_return(&num_events) == 0)
  89                         release_pmc_hardware();
  90                 mutex_unlock(&pmc_reserve_mutex);
  91         }
  92 }
  93
  94 static int hw_perf_cache_event(int config, int *evp)
  95 {
  96         unsigned long type, op, result;
  97         int ev;
  98
  99         if (!sh_pmu->cache_events)
 100                 return -EINVAL;
 101
 102         /* unpack config */
 103         type = config & 0xff;
 104         op = (config >> 8) & 0xff;
 105         result = (config >> 16) & 0xff;
 106
 107         if (type >= PERF_COUNT_HW_CACHE_MAX ||
 108             op >= PERF_COUNT_HW_CACHE_OP_MAX ||
 109             result >= PERF_COUNT_HW_CACHE_RESULT_MAX)
 110                 return -EINVAL;
 111
 112         ev = (*sh_pmu->cache_events)[type][op][result];
 113         if (ev == 0)
 114                 return -EOPNOTSUPP;
 115         if (ev == -1)
 116                 return -EINVAL;
 117         *evp = ev;
 118         return 0;
 119 }
 120
 121 static int __hw_perf_event_init(struct perf_event *event)
 122 {
 123         struct perf_event_attr *attr = &event->attr;
 124         struct hw_perf_event *hwc = &event->hw;
 125         int config = -1;
 126         int err;
 127
 128         if (!sh_pmu_initialized())
 129                 return -ENODEV;
 130
 131         /*
 132          * All of the on-chip counters are "limited", in that they have
 133          * no interrupts, and are therefore unable to do sampling without
 134          * further work and timer assistance.
 135          */
 136         if (hwc->sample_period)
 137                 return -EINVAL;
 138
 139         /*
 140          * See if we need to reserve the counter.
 141          *
 142          * If no events are currently in use, then we have to take a
 143          * mutex to ensure that we don't race with another task doing
 144          * reserve_pmc_hardware or release_pmc_hardware.
 145          */
 146         err = 0;
 147         if (!atomic_inc_not_zero(&num_events)) {
 148                 mutex_lock(&pmc_reserve_mutex);
 149                 if (atomic_read(&num_events) == 0 &&
 150                     reserve_pmc_hardware())
 151                         err = -EBUSY;
 152                 else
 153                         atomic_inc(&num_events);
 154                 mutex_unlock(&pmc_reserve_mutex);
 155         }
 156
 157         if (err)
 158                 return err;
 159
 160         event->destroy = hw_perf_event_destroy;
 161
 162         switch (attr->type) {
 163         case PERF_TYPE_RAW:
 164                 config = attr->config & sh_pmu->raw_event_mask;
 165                 break;
 166         case PERF_TYPE_HW_CACHE:
 167                 err = hw_perf_cache_event(attr->config, &config);
 168                 if (err)
 169                         return err;
 170                 break;
 171         case PERF_TYPE_HARDWARE:
 172                 if (attr->config >= sh_pmu->max_events)
 173                         return -EINVAL;
 174
 175                 config = sh_pmu->event_map(attr->config);
 176                 break;
 177         }
 178
 179         if (config == -1)
 180                 return -EINVAL;
 181
 182         hwc->config |= config;
 183
 184         return 0;
 185 }
 186
 187 static void sh_perf_event_update(struct perf_event *event,
 188                                    struct hw_perf_event *hwc, int idx)
 189 {
 190         u64 prev_raw_count, new_raw_count;
 191         s64 delta;
 192         int shift = 0;
 193
 194         /*
 195          * Depending on the counter configuration, they may or may not
 196          * be chained, in which case the previous counter value can be
 197          * updated underneath us if the lower-half overflows.
 198          *
 199          * Our tactic to handle this is to first atomically read and
 200          * exchange a new raw count - then add that new-prev delta
 201          * count to the generic counter atomically.
 202          *
 203          * As there is no interrupt associated with the overflow events,
 204          * this is the simplest approach for maintaining consistency.
 205          */
 206 again:
 207         prev_raw_count = local64_read(&hwc->prev_count);
 208         new_raw_count = sh_pmu->read(idx);
 209
 210         if (local64_cmpxchg(&hwc->prev_count, prev_raw_count,
 211                              new_raw_count) != prev_raw_count)
 212                 goto again;
 213
 214         /*
 215          * Now we have the new raw value and have updated the prev
 216          * timestamp already. We can now calculate the elapsed delta
 217          * (counter-)time and add that to the generic counter.
 218          *
 219          * Careful, not all hw sign-extends above the physical width
 220          * of the count.
 221          */
 222         delta = (new_raw_count << shift) - (prev_raw_count << shift);
 223         delta >>= shift;
 224
 225         local64_add(delta, &event->count);
 226 }
 227
 228 static void sh_pmu_stop(struct perf_event *event, int flags)
 229 {
 230         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 231         struct hw_perf_event *hwc = &event->hw;
 232         int idx = hwc->idx;
 233
 234         if (!(event->hw.state & PERF_HES_STOPPED)) {
 235                 sh_pmu->disable(hwc, idx);
 236                 cpuc->events[idx] = NULL;
 237                 event->hw.state |= PERF_HES_STOPPED;
 238         }
 239
 240         if ((flags & PERF_EF_UPDATE) && !(event->hw.state & PERF_HES_UPTODATE)) {
 241                 sh_perf_event_update(event, &event->hw, idx);
 242                 event->hw.state |= PERF_HES_UPTODATE;
 243         }
 244 }
 245
 246 static void sh_pmu_start(struct perf_event *event, int flags)
 247 {
 248         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 249         struct hw_perf_event *hwc = &event->hw;
 250         int idx = hwc->idx;
 251
 252         if (WARN_ON_ONCE(idx == -1))
 253                 return;
 254
 255         if (flags & PERF_EF_RELOAD)
 256                 WARN_ON_ONCE(!(event->hw.state & PERF_HES_UPTODATE));
 257
 258         cpuc->events[idx] = event;
 259         event->hw.state = 0;
 260         sh_pmu->enable(hwc, idx);
 261 }
 262
 263 static void sh_pmu_del(struct perf_event *event, int flags)
 264 {
 265         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 266
 267         sh_pmu_stop(event, PERF_EF_UPDATE);
 268         __clear_bit(event->hw.idx, cpuc->used_mask);
 269
 270         perf_event_update_userpage(event);
 271 }
 272
 273 static int sh_pmu_add(struct perf_event *event, int flags)
 274 {
 275         struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
 276         struct hw_perf_event *hwc = &event->hw;
 277         int idx = hwc->idx;
 278         int ret = -EAGAIN;
 279
 280         perf_pmu_disable(event->pmu);
 281
 282         if (__test_and_set_bit(idx, cpuc->used_mask)) {
 283                 idx = find_first_zero_bit(cpuc->used_mask, sh_pmu->num_events);
 284                 if (idx == sh_pmu->num_events)
 285                         goto out;
 286
 287                 __set_bit(idx, cpuc->used_mask);
 288                 hwc->idx = idx;
 289         }
 290
 291         sh_pmu->disable(hwc, idx);
 292
 293         event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
 294         if (flags & PERF_EF_START)
 295                 sh_pmu_start(event, PERF_EF_RELOAD);
 296
 297         perf_event_update_userpage(event);
 298         ret = 0;
 299 out:
 300         perf_pmu_enable(event->pmu);
 301         return ret;
 302 }
 303
 304 static void sh_pmu_read(struct perf_event *event)
 305 {
 306         sh_perf_event_update(event, &event->hw, event->hw.idx);
 307 }
 308
 309 static int sh_pmu_event_init(struct perf_event *event)
 310 {
 311         int err;
 312
 313         /* does not support taken branch sampling */
 314         if (has_branch_stack(event))
 315                 return -EOPNOTSUPP;
 316
 317         switch (event->attr.type) {
 318         case PERF_TYPE_RAW:
 319         case PERF_TYPE_HW_CACHE:
 320         case PERF_TYPE_HARDWARE:
 321                 err = __hw_perf_event_init(event);
 322                 break;
 323
 324         default:
 325                 return -ENOENT;
 326         }
 327
 328         if (unlikely(err)) {
 329                 if (event->destroy)
 330                         event->destroy(event);
 331         }
 332
 333         return err;
 334 }
 335
 336 static void sh_pmu_enable(struct pmu *pmu)
 337 {
 338         if (!sh_pmu_initialized())
 339                 return;
 340
 341         sh_pmu->enable_all();
 342 }
 343
 344 static void sh_pmu_disable(struct pmu *pmu)
 345 {
 346         if (!sh_pmu_initialized())
 347                 return;
 348
 349         sh_pmu->disable_all();
 350 }
 351
 352 static struct pmu pmu = {
 353         .pmu_enable     = sh_pmu_enable,
 354         .pmu_disable    = sh_pmu_disable,
 355         .event_init     = sh_pmu_event_init,
 356         .add            = sh_pmu_add,
 357         .del            = sh_pmu_del,
 358         .start          = sh_pmu_start,
 359         .stop           = sh_pmu_stop,
 360         .read           = sh_pmu_read,
 361 };
 362
 363 static void sh_pmu_setup(int cpu)
 364 {
 365         struct cpu_hw_events *cpuhw = &per_cpu(cpu_hw_events, cpu);
 366
 367         memset(cpuhw, 0, sizeof(struct cpu_hw_events));
 368 }
 369
 370 static int __cpuinit
 371 sh_pmu_notifier(struct notifier_block *self, unsigned long action, void *hcpu)
 372 {
 373         unsigned int cpu = (long)hcpu;
 374
 375         switch (action & ~CPU_TASKS_FROZEN) {
 376         case CPU_UP_PREPARE:
 377                 sh_pmu_setup(cpu);
 378                 break;
 379
 380         default:
 381                 break;
 382         }
 383
 384         return NOTIFY_OK;
 385 }
 386
 387 int __cpuinit register_sh_pmu(struct sh_pmu *_pmu)
 388 {
 389         if (sh_pmu)
 390                 return -EBUSY;
 391         sh_pmu = _pmu;
 392
 393         pr_info("Performance Events: %s support registered\n", _pmu->name);
 394
 395         WARN_ON(_pmu->num_events > MAX_HWEVENTS);
 396
 397         perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW);
 398         perf_cpu_notifier(sh_pmu_notifier);
 399         return 0;
 400 }