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         struct perf_event *pevent;
  75
  76         if (!counter_config[event].enabled || perf_events[cpu][event])
  77                 return 0;
  78
  79         pevent = perf_event_create_kernel_counter(&counter_config[event].attr,
  80                                                   cpu, NULL,
  81                                                   op_overflow_handler);
  82
  83         if (IS_ERR(pevent))
  84                 return PTR_ERR(pevent);
  85
  86         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                 return -EBUSY;
  91         }
  92
  93         perf_events[cpu][event] = pevent;
  94
  95         return 0;
  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                                 return ret;
 121                 }
 122         }
 123
 124         return ret;
 125 }
 126
 127 /*
 128  * Called by oprofile_perf_stop at the end of a profiling run.
 129  */
 130 static void op_perf_stop(void)
 131 {
 132         int cpu, event;
 133
 134         for_each_online_cpu(cpu)
 135                 for (event = 0; event < num_counters; ++event)
 136                         op_destroy_counter(cpu, event);
 137 }
 138
 139 static int oprofile_perf_create_files(struct super_block *sb, struct dentry *root)
 140 {
 141         unsigned int i;
 142
 143         for (i = 0; i < num_counters; i++) {
 144                 struct dentry *dir;
 145                 char buf[4];
 146
 147                 snprintf(buf, sizeof buf, "%d", i);
 148                 dir = oprofilefs_mkdir(sb, root, buf);
 149                 oprofilefs_create_ulong(sb, dir, "enabled", &counter_config[i].enabled);
 150                 oprofilefs_create_ulong(sb, dir, "event", &counter_config[i].event);
 151                 oprofilefs_create_ulong(sb, dir, "count", &counter_config[i].count);
 152                 oprofilefs_create_ulong(sb, dir, "unit_mask", &counter_config[i].unit_mask);
 153                 oprofilefs_create_ulong(sb, dir, "kernel", &counter_config[i].kernel);
 154                 oprofilefs_create_ulong(sb, dir, "user", &counter_config[i].user);
 155         }
 156
 157         return 0;
 158 }
 159
 160 static int oprofile_perf_setup(void)
 161 {
 162         spin_lock(&oprofilefs_lock);
 163         op_perf_setup();
 164         spin_unlock(&oprofilefs_lock);
 165         return 0;
 166 }
 167
 168 static int oprofile_perf_start(void)
 169 {
 170         int ret = -EBUSY;
 171
 172         mutex_lock(&oprofile_perf_mutex);
 173         if (!oprofile_perf_enabled) {
 174                 ret = 0;
 175                 op_perf_start();
 176                 oprofile_perf_enabled = 1;
 177         }
 178         mutex_unlock(&oprofile_perf_mutex);
 179         return ret;
 180 }
 181
 182 static void oprofile_perf_stop(void)
 183 {
 184         mutex_lock(&oprofile_perf_mutex);
 185         if (oprofile_perf_enabled)
 186                 op_perf_stop();
 187         oprofile_perf_enabled = 0;
 188         mutex_unlock(&oprofile_perf_mutex);
 189 }
 190
 191 #ifdef CONFIG_PM
 192 static int oprofile_perf_suspend(struct platform_device *dev, pm_message_t state)
 193 {
 194         mutex_lock(&oprofile_perf_mutex);
 195         if (oprofile_perf_enabled)
 196                 op_perf_stop();
 197         mutex_unlock(&oprofile_perf_mutex);
 198         return 0;
 199 }
 200
 201 static int oprofile_perf_resume(struct platform_device *dev)
 202 {
 203         mutex_lock(&oprofile_perf_mutex);
 204         if (oprofile_perf_enabled && op_perf_start())
 205                 oprofile_perf_enabled = 0;
 206         mutex_unlock(&oprofile_perf_mutex);
 207         return 0;
 208 }
 209
 210 static struct platform_driver oprofile_driver = {
 211         .driver         = {
 212                 .name           = "oprofile-perf",
 213         },
 214         .resume         = oprofile_perf_resume,
 215         .suspend        = oprofile_perf_suspend,
 216 };
 217
 218 static struct platform_device *oprofile_pdev;
 219
 220 static int __init init_driverfs(void)
 221 {
 222         int ret;
 223
 224         ret = platform_driver_register(&oprofile_driver);
 225         if (ret)
 226                 return ret;
 227
 228         oprofile_pdev = platform_device_register_simple(
 229                                 oprofile_driver.driver.name, 0, NULL, 0);
 230         if (IS_ERR(oprofile_pdev)) {
 231                 ret = PTR_ERR(oprofile_pdev);
 232                 platform_driver_unregister(&oprofile_driver);
 233         }
 234
 235         return ret;
 236 }
 237
 238 static void __exit exit_driverfs(void)
 239 {
 240         platform_device_unregister(oprofile_pdev);
 241         platform_driver_unregister(&oprofile_driver);
 242 }
 243 #else
 244 static int __init init_driverfs(void) { return 0; }
 245 #define exit_driverfs() do { } while (0)
 246 #endif /* CONFIG_PM */
 247
 248 void oprofile_perf_exit(void)
 249 {
 250         int cpu, id;
 251         struct perf_event *event;
 252
 253         for_each_possible_cpu(cpu) {
 254                 for (id = 0; id < num_counters; ++id) {
 255                         event = perf_events[cpu][id];
 256                         if (event)
 257                                 perf_event_release_kernel(event);
 258                 }
 259
 260                 kfree(perf_events[cpu]);
 261         }
 262
 263         kfree(counter_config);
 264         exit_driverfs();
 265 }
 266
 267 int __init oprofile_perf_init(struct oprofile_operations *ops)
 268 {
 269         int cpu, ret = 0;
 270
 271         ret = init_driverfs();
 272         if (ret)
 273                 return ret;
 274
 275         memset(&perf_events, 0, sizeof(perf_events));
 276
 277         num_counters = perf_num_counters();
 278         if (num_counters <= 0) {
 279                 pr_info("oprofile: no performance counters\n");
 280                 ret = -ENODEV;
 281                 goto out;
 282         }
 283
 284         counter_config = kcalloc(num_counters,
 285                         sizeof(struct op_counter_config), GFP_KERNEL);
 286
 287         if (!counter_config) {
 288                 pr_info("oprofile: failed to allocate %d "
 289                                 "counters\n", num_counters);
 290                 ret = -ENOMEM;
 291                 num_counters = 0;
 292                 goto out;
 293         }
 294
 295         for_each_possible_cpu(cpu) {
 296                 perf_events[cpu] = kcalloc(num_counters,
 297                                 sizeof(struct perf_event *), GFP_KERNEL);
 298                 if (!perf_events[cpu]) {
 299                         pr_info("oprofile: failed to allocate %d perf events "
 300                                         "for cpu %d\n", num_counters, cpu);
 301                         ret = -ENOMEM;
 302                         goto out;
 303                 }
 304         }
 305
 306         ops->create_files       = oprofile_perf_create_files;
 307         ops->setup              = oprofile_perf_setup;
 308         ops->start              = oprofile_perf_start;
 309         ops->stop               = oprofile_perf_stop;
 310         ops->shutdown           = oprofile_perf_stop;
 311         ops->cpu_type           = op_name_from_perf_id();
 312
 313         if (!ops->cpu_type)
 314                 ret = -ENODEV;
 315         else
 316                 pr_info("oprofile: using %s\n", ops->cpu_type);
 317
 318 out:
 319         if (ret)
 320                 oprofile_perf_exit();
 321
 322         return ret;
 323 }