drivers/oprofile/oprofile_perf.c

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