linux/drivers/oprofile/oprofile_perf.c
<<
>>
Prefs
   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright 2010 ARM Ltd.
   4 * Copyright 2012 Advanced Micro Devices, Inc., Robert Richter
   5 *
   6 * Perf-events backend for OProfile.
   7 */
   8#include <linux/perf_event.h>
   9#include <linux/platform_device.h>
  10#include <linux/oprofile.h>
  11#include <linux/slab.h>
  12
  13/*
  14 * Per performance monitor configuration as set via oprofilefs.
  15 */
  16struct op_counter_config {
  17        unsigned long count;
  18        unsigned long enabled;
  19        unsigned long event;
  20        unsigned long unit_mask;
  21        unsigned long kernel;
  22        unsigned long user;
  23        struct perf_event_attr attr;
  24};
  25
  26static int oprofile_perf_enabled;
  27static DEFINE_MUTEX(oprofile_perf_mutex);
  28
  29static struct op_counter_config *counter_config;
  30static DEFINE_PER_CPU(struct perf_event **, perf_events);
  31static int num_counters;
  32
  33/*
  34 * Overflow callback for oprofile.
  35 */
  36static void op_overflow_handler(struct perf_event *event,
  37                        struct perf_sample_data *data, struct pt_regs *regs)
  38{
  39        int id;
  40        u32 cpu = smp_processor_id();
  41
  42        for (id = 0; id < num_counters; ++id)
  43                if (per_cpu(perf_events, cpu)[id] == event)
  44                        break;
  45
  46        if (id != num_counters)
  47                oprofile_add_sample(regs, id);
  48        else
  49                pr_warn("oprofile: ignoring spurious overflow on cpu %u\n",
  50                        cpu);
  51}
  52
  53/*
  54 * Called by oprofile_perf_setup to create perf attributes to mirror the oprofile
  55 * settings in counter_config. Attributes are created as `pinned' events and
  56 * so are permanently scheduled on the PMU.
  57 */
  58static void op_perf_setup(void)
  59{
  60        int i;
  61        u32 size = sizeof(struct perf_event_attr);
  62        struct perf_event_attr *attr;
  63
  64        for (i = 0; i < num_counters; ++i) {
  65                attr = &counter_config[i].attr;
  66                memset(attr, 0, size);
  67                attr->type              = PERF_TYPE_RAW;
  68                attr->size              = size;
  69                attr->config            = counter_config[i].event;
  70                attr->sample_period     = counter_config[i].count;
  71                attr->pinned            = 1;
  72        }
  73}
  74
  75static int op_create_counter(int cpu, int event)
  76{
  77        struct perf_event *pevent;
  78
  79        if (!counter_config[event].enabled || per_cpu(perf_events, cpu)[event])
  80                return 0;
  81
  82        pevent = perf_event_create_kernel_counter(&counter_config[event].attr,
  83                                                  cpu, NULL,
  84                                                  op_overflow_handler, NULL);
  85
  86        if (IS_ERR(pevent))
  87                return PTR_ERR(pevent);
  88
  89        if (pevent->state != PERF_EVENT_STATE_ACTIVE) {
  90                perf_event_release_kernel(pevent);
  91                pr_warn("oprofile: failed to enable event %d on CPU %d\n",
  92                        event, cpu);
  93                return -EBUSY;
  94        }
  95
  96        per_cpu(perf_events, cpu)[event] = pevent;
  97
  98        return 0;
  99}
 100
 101static void op_destroy_counter(int cpu, int event)
 102{
 103        struct perf_event *pevent = per_cpu(perf_events, cpu)[event];
 104
 105        if (pevent) {
 106                perf_event_release_kernel(pevent);
 107                per_cpu(perf_events, cpu)[event] = NULL;
 108        }
 109}
 110
 111/*
 112 * Called by oprofile_perf_start to create active perf events based on the
 113 * perviously configured attributes.
 114 */
 115static int op_perf_start(void)
 116{
 117        int cpu, event, ret = 0;
 118
 119        for_each_online_cpu(cpu) {
 120                for (event = 0; event < num_counters; ++event) {
 121                        ret = op_create_counter(cpu, event);
 122                        if (ret)
 123                                return ret;
 124                }
 125        }
 126
 127        return ret;
 128}
 129
 130/*
 131 * Called by oprofile_perf_stop at the end of a profiling run.
 132 */
 133static void op_perf_stop(void)
 134{
 135        int cpu, event;
 136
 137        for_each_online_cpu(cpu)
 138                for (event = 0; event < num_counters; ++event)
 139                        op_destroy_counter(cpu, event);
 140}
 141
 142static int oprofile_perf_create_files(struct dentry *root)
 143{
 144        unsigned int i;
 145
 146        for (i = 0; i < num_counters; i++) {
 147                struct dentry *dir;
 148                char buf[4];
 149
 150                snprintf(buf, sizeof buf, "%d", i);
 151                dir = oprofilefs_mkdir(root, buf);
 152                oprofilefs_create_ulong(dir, "enabled", &counter_config[i].enabled);
 153                oprofilefs_create_ulong(dir, "event", &counter_config[i].event);
 154                oprofilefs_create_ulong(dir, "count", &counter_config[i].count);
 155                oprofilefs_create_ulong(dir, "unit_mask", &counter_config[i].unit_mask);
 156                oprofilefs_create_ulong(dir, "kernel", &counter_config[i].kernel);
 157                oprofilefs_create_ulong(dir, "user", &counter_config[i].user);
 158        }
 159
 160        return 0;
 161}
 162
 163static int oprofile_perf_setup(void)
 164{
 165        raw_spin_lock(&oprofilefs_lock);
 166        op_perf_setup();
 167        raw_spin_unlock(&oprofilefs_lock);
 168        return 0;
 169}
 170
 171static int oprofile_perf_start(void)
 172{
 173        int ret = -EBUSY;
 174
 175        mutex_lock(&oprofile_perf_mutex);
 176        if (!oprofile_perf_enabled) {
 177                ret = 0;
 178                op_perf_start();
 179                oprofile_perf_enabled = 1;
 180        }
 181        mutex_unlock(&oprofile_perf_mutex);
 182        return ret;
 183}
 184
 185static void oprofile_perf_stop(void)
 186{
 187        mutex_lock(&oprofile_perf_mutex);
 188        if (oprofile_perf_enabled)
 189                op_perf_stop();
 190        oprofile_perf_enabled = 0;
 191        mutex_unlock(&oprofile_perf_mutex);
 192}
 193
 194#ifdef CONFIG_PM
 195
 196static int oprofile_perf_suspend(struct platform_device *dev, pm_message_t state)
 197{
 198        mutex_lock(&oprofile_perf_mutex);
 199        if (oprofile_perf_enabled)
 200                op_perf_stop();
 201        mutex_unlock(&oprofile_perf_mutex);
 202        return 0;
 203}
 204
 205static int oprofile_perf_resume(struct platform_device *dev)
 206{
 207        mutex_lock(&oprofile_perf_mutex);
 208        if (oprofile_perf_enabled && op_perf_start())
 209                oprofile_perf_enabled = 0;
 210        mutex_unlock(&oprofile_perf_mutex);
 211        return 0;
 212}
 213
 214static struct platform_driver oprofile_driver = {
 215        .driver         = {
 216                .name           = "oprofile-perf",
 217        },
 218        .resume         = oprofile_perf_resume,
 219        .suspend        = oprofile_perf_suspend,
 220};
 221
 222static struct platform_device *oprofile_pdev;
 223
 224static int __init init_driverfs(void)
 225{
 226        int ret;
 227
 228        ret = platform_driver_register(&oprofile_driver);
 229        if (ret)
 230                return ret;
 231
 232        oprofile_pdev = platform_device_register_simple(
 233                                oprofile_driver.driver.name, 0, NULL, 0);
 234        if (IS_ERR(oprofile_pdev)) {
 235                ret = PTR_ERR(oprofile_pdev);
 236                platform_driver_unregister(&oprofile_driver);
 237        }
 238
 239        return ret;
 240}
 241
 242static void exit_driverfs(void)
 243{
 244        platform_device_unregister(oprofile_pdev);
 245        platform_driver_unregister(&oprofile_driver);
 246}
 247
 248#else
 249
 250static inline int  init_driverfs(void) { return 0; }
 251static inline void exit_driverfs(void) { }
 252
 253#endif /* CONFIG_PM */
 254
 255void oprofile_perf_exit(void)
 256{
 257        int cpu, id;
 258        struct perf_event *event;
 259
 260        for_each_possible_cpu(cpu) {
 261                for (id = 0; id < num_counters; ++id) {
 262                        event = per_cpu(perf_events, cpu)[id];
 263                        if (event)
 264                                perf_event_release_kernel(event);
 265                }
 266
 267                kfree(per_cpu(perf_events, cpu));
 268        }
 269
 270        kfree(counter_config);
 271        exit_driverfs();
 272}
 273
 274int __init oprofile_perf_init(struct oprofile_operations *ops)
 275{
 276        int cpu, ret = 0;
 277
 278        ret = init_driverfs();
 279        if (ret)
 280                return ret;
 281
 282        num_counters = perf_num_counters();
 283        if (num_counters <= 0) {
 284                pr_info("oprofile: no performance counters\n");
 285                ret = -ENODEV;
 286                goto out;
 287        }
 288
 289        counter_config = kcalloc(num_counters,
 290                        sizeof(struct op_counter_config), GFP_KERNEL);
 291
 292        if (!counter_config) {
 293                pr_info("oprofile: failed to allocate %d "
 294                                "counters\n", num_counters);
 295                ret = -ENOMEM;
 296                num_counters = 0;
 297                goto out;
 298        }
 299
 300        for_each_possible_cpu(cpu) {
 301                per_cpu(perf_events, cpu) = kcalloc(num_counters,
 302                                sizeof(struct perf_event *), GFP_KERNEL);
 303                if (!per_cpu(perf_events, cpu)) {
 304                        pr_info("oprofile: failed to allocate %d perf events "
 305                                        "for cpu %d\n", num_counters, cpu);
 306                        ret = -ENOMEM;
 307                        goto out;
 308                }
 309        }
 310
 311        ops->create_files       = oprofile_perf_create_files;
 312        ops->setup              = oprofile_perf_setup;
 313        ops->start              = oprofile_perf_start;
 314        ops->stop               = oprofile_perf_stop;
 315        ops->shutdown           = oprofile_perf_stop;
 316        ops->cpu_type           = op_name_from_perf_id();
 317
 318        if (!ops->cpu_type)
 319                ret = -ENODEV;
 320        else
 321                pr_info("oprofile: using %s\n", ops->cpu_type);
 322
 323out:
 324        if (ret)
 325                oprofile_perf_exit();
 326
 327        return ret;
 328}
 329