drivers/oprofile/oprofile_perf.c

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