lttng-context-perf-counters.c

   1 /*
   2  * lttng-context-perf-counters.c
   3  *
   4  * LTTng performance monitoring counters (perf-counters) integration module.
   5  *
   6  * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/slab.h>
  25 #include <linux/perf_event.h>
  26 #include <linux/list.h>
  27 #include <linux/string.h>
  28 #include <linux/cpu.h>
  29 #include <lttng-events.h>
  30 #include <wrapper/ringbuffer/frontend_types.h>
  31 #include <wrapper/vmalloc.h>
  32 #include <wrapper/perf.h>
  33 #include <lttng-tracer.h>
  34
  35 static
  36 size_t perf_counter_get_size(size_t offset)
  37 {
  38         size_t size = 0;
  39
  40         size += lib_ring_buffer_align(offset, lttng_alignof(uint64_t));
  41         size += sizeof(uint64_t);
  42         return size;
  43 }
  44
  45 static
  46 void perf_counter_record(struct lttng_ctx_field *field,
  47                          struct lib_ring_buffer_ctx *ctx,
  48                          struct lttng_channel *chan)
  49 {
  50         struct perf_event *event;
  51         uint64_t value;
  52
  53         event = field->u.perf_counter->e[ctx->cpu];
  54         if (likely(event)) {
  55                 if (unlikely(event->state == PERF_EVENT_STATE_ERROR)) {
  56                         value = 0;
  57                 } else {
  58                         event->pmu->read(event);
  59                         value = local64_read(&event->count);
  60                 }
  61         } else {
  62                 /*
  63                  * Perf chooses not to be clever and not to support enabling a
  64                  * perf counter before the cpu is brought up. Therefore, we need
  65                  * to support having events coming (e.g. scheduler events)
  66                  * before the counter is setup. Write an arbitrary 0 in this
  67                  * case.
  68                  */
  69                 value = 0;
  70         }
  71         lib_ring_buffer_align_ctx(ctx, lttng_alignof(value));
  72         chan->ops->event_write(ctx, &value, sizeof(value));
  73 }
  74
  75 #if defined(CONFIG_PERF_EVENTS) && (LINUX_VERSION_CODE >= KERNEL_VERSION(3,0,99))
  76 static
  77 void overflow_callback(struct perf_event *event,
  78                        struct perf_sample_data *data,
  79                        struct pt_regs *regs)
  80 {
  81 }
  82 #else
  83 static
  84 void overflow_callback(struct perf_event *event, int nmi,
  85                        struct perf_sample_data *data,
  86                        struct pt_regs *regs)
  87 {
  88 }
  89 #endif
  90
  91 static
  92 void lttng_destroy_perf_counter_field(struct lttng_ctx_field *field)
  93 {
  94         struct perf_event **events = field->u.perf_counter->e;
  95
  96 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
  97         {
  98                 int ret;
  99
 100                 ret = cpuhp_state_remove_instance(lttng_hp_online,
 101                         &field->u.perf_counter->cpuhp_online.node);
 102                 WARN_ON(ret);
 103                 ret = cpuhp_state_remove_instance(lttng_hp_prepare,
 104                         &field->u.perf_counter->cpuhp_prepare.node);
 105                 WARN_ON(ret);
 106         }
 107 #else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
 108         {
 109                 int cpu;
 110
 111                 get_online_cpus();
 112                 for_each_online_cpu(cpu)
 113                         perf_event_release_kernel(events[cpu]);
 114                 put_online_cpus();
 115 #ifdef CONFIG_HOTPLUG_CPU
 116                 unregister_cpu_notifier(&field->u.perf_counter->nb);
 117 #endif
 118         }
 119 #endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
 120         kfree(field->event_field.name);
 121         kfree(field->u.perf_counter->attr);
 122         kfree(events);
 123         kfree(field->u.perf_counter);
 124 }
 125
 126 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
 127
 128 int lttng_cpuhp_perf_counter_online(unsigned int cpu,
 129                 struct lttng_cpuhp_node *node)
 130 {
 131         struct lttng_perf_counter_field *perf_field =
 132                 container_of(node, struct lttng_perf_counter_field,
 133                                 cpuhp_online);
 134         struct perf_event **events = perf_field->e;
 135         struct perf_event_attr *attr = perf_field->attr;
 136         struct perf_event *pevent;
 137
 138         pevent = wrapper_perf_event_create_kernel_counter(attr,
 139                         cpu, NULL, overflow_callback);
 140         if (!pevent || IS_ERR(pevent))
 141                 return -EINVAL;
 142         if (pevent->state == PERF_EVENT_STATE_ERROR) {
 143                 perf_event_release_kernel(pevent);
 144                 return -EINVAL;
 145         }
 146         barrier();      /* Create perf counter before setting event */
 147         events[cpu] = pevent;
 148         return 0;
 149 }
 150
 151 int lttng_cpuhp_perf_counter_dead(unsigned int cpu,
 152                 struct lttng_cpuhp_node *node)
 153 {
 154         struct lttng_perf_counter_field *perf_field =
 155                 container_of(node, struct lttng_perf_counter_field,
 156                                 cpuhp_prepare);
 157         struct perf_event **events = perf_field->e;
 158         struct perf_event *pevent;
 159
 160         pevent = events[cpu];
 161         events[cpu] = NULL;
 162         barrier();      /* NULLify event before perf counter teardown */
 163         perf_event_release_kernel(pevent);
 164         return 0;
 165 }
 166
 167 #else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
 168
 169 #ifdef CONFIG_HOTPLUG_CPU
 170
 171 /**
 172  *      lttng_perf_counter_hp_callback - CPU hotplug callback
 173  *      @nb: notifier block
 174  *      @action: hotplug action to take
 175  *      @hcpu: CPU number
 176  *
 177  *      Returns the success/failure of the operation. (%NOTIFY_OK, %NOTIFY_BAD)
 178  *
 179  * We can setup perf counters when the cpu is online (up prepare seems to be too
 180  * soon).
 181  */
 182 static
 183 int lttng_perf_counter_cpu_hp_callback(struct notifier_block *nb,
 184                                                  unsigned long action,
 185                                                  void *hcpu)
 186 {
 187         unsigned int cpu = (unsigned long) hcpu;
 188         struct lttng_perf_counter_field *perf_field =
 189                 container_of(nb, struct lttng_perf_counter_field, nb);
 190         struct perf_event **events = perf_field->e;
 191         struct perf_event_attr *attr = perf_field->attr;
 192         struct perf_event *pevent;
 193
 194         if (!perf_field->hp_enable)
 195                 return NOTIFY_OK;
 196
 197         switch (action) {
 198         case CPU_ONLINE:
 199         case CPU_ONLINE_FROZEN:
 200                 pevent = wrapper_perf_event_create_kernel_counter(attr,
 201                                 cpu, NULL, overflow_callback);
 202                 if (!pevent || IS_ERR(pevent))
 203                         return NOTIFY_BAD;
 204                 if (pevent->state == PERF_EVENT_STATE_ERROR) {
 205                         perf_event_release_kernel(pevent);
 206                         return NOTIFY_BAD;
 207                 }
 208                 barrier();      /* Create perf counter before setting event */
 209                 events[cpu] = pevent;
 210                 break;
 211         case CPU_UP_CANCELED:
 212         case CPU_UP_CANCELED_FROZEN:
 213         case CPU_DEAD:
 214         case CPU_DEAD_FROZEN:
 215                 pevent = events[cpu];
 216                 events[cpu] = NULL;
 217                 barrier();      /* NULLify event before perf counter teardown */
 218                 perf_event_release_kernel(pevent);
 219                 break;
 220         }
 221         return NOTIFY_OK;
 222 }
 223
 224 #endif
 225
 226 #endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
 227
 228 int lttng_add_perf_counter_to_ctx(uint32_t type,
 229                                   uint64_t config,
 230                                   const char *name,
 231                                   struct lttng_ctx **ctx)
 232 {
 233         struct lttng_ctx_field *field;
 234         struct lttng_perf_counter_field *perf_field;
 235         struct perf_event **events;
 236         struct perf_event_attr *attr;
 237         int ret;
 238         char *name_alloc;
 239
 240         events = kzalloc(num_possible_cpus() * sizeof(*events), GFP_KERNEL);
 241         if (!events)
 242                 return -ENOMEM;
 243
 244         attr = kzalloc(sizeof(struct perf_event_attr), GFP_KERNEL);
 245         if (!attr) {
 246                 ret = -ENOMEM;
 247                 goto error_attr;
 248         }
 249
 250         attr->type = type;
 251         attr->config = config;
 252         attr->size = sizeof(struct perf_event_attr);
 253         attr->pinned = 1;
 254         attr->disabled = 0;
 255
 256         perf_field = kzalloc(sizeof(struct lttng_perf_counter_field), GFP_KERNEL);
 257         if (!perf_field) {
 258                 ret = -ENOMEM;
 259                 goto error_alloc_perf_field;
 260         }
 261         perf_field->e = events;
 262         perf_field->attr = attr;
 263
 264         name_alloc = kstrdup(name, GFP_KERNEL);
 265         if (!name_alloc) {
 266                 ret = -ENOMEM;
 267                 goto name_alloc_error;
 268         }
 269
 270         field = lttng_append_context(ctx);
 271         if (!field) {
 272                 ret = -ENOMEM;
 273                 goto append_context_error;
 274         }
 275         if (lttng_find_context(*ctx, name_alloc)) {
 276                 ret = -EEXIST;
 277                 goto find_error;
 278         }
 279
 280 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
 281
 282         perf_field->cpuhp_prepare.component = LTTNG_CONTEXT_PERF_COUNTERS;
 283         ret = cpuhp_state_add_instance(lttng_hp_prepare,
 284                 &perf_field->cpuhp_prepare.node);
 285         if (ret)
 286                 goto cpuhp_prepare_error;
 287
 288         perf_field->cpuhp_online.component = LTTNG_CONTEXT_PERF_COUNTERS;
 289         ret = cpuhp_state_add_instance(lttng_hp_online,
 290                 &perf_field->cpuhp_online.node);
 291         if (ret)
 292                 goto cpuhp_online_error;
 293
 294 #else   /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
 295         {
 296                 int cpu;
 297
 298 #ifdef CONFIG_HOTPLUG_CPU
 299                 perf_field->nb.notifier_call =
 300                         lttng_perf_counter_cpu_hp_callback;
 301                 perf_field->nb.priority = 0;
 302                 register_cpu_notifier(&perf_field->nb);
 303 #endif
 304                 get_online_cpus();
 305                 for_each_online_cpu(cpu) {
 306                         events[cpu] = wrapper_perf_event_create_kernel_counter(attr,
 307                                                 cpu, NULL, overflow_callback);
 308                         if (!events[cpu] || IS_ERR(events[cpu])) {
 309                                 ret = -EINVAL;
 310                                 goto counter_error;
 311                         }
 312                         if (events[cpu]->state == PERF_EVENT_STATE_ERROR) {
 313                                 ret = -EBUSY;
 314                                 goto counter_busy;
 315                         }
 316                 }
 317                 put_online_cpus();
 318                 perf_field->hp_enable = 1;
 319         }
 320 #endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
 321
 322         field->destroy = lttng_destroy_perf_counter_field;
 323
 324         field->event_field.name = name_alloc;
 325         field->event_field.type.atype = atype_integer;
 326         field->event_field.type.u.basic.integer.size = sizeof(uint64_t) * CHAR_BIT;
 327         field->event_field.type.u.basic.integer.alignment = lttng_alignof(uint64_t) * CHAR_BIT;
 328         field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(uint64_t);
 329         field->event_field.type.u.basic.integer.reverse_byte_order = 0;
 330         field->event_field.type.u.basic.integer.base = 10;
 331         field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
 332         field->get_size = perf_counter_get_size;
 333         field->record = perf_counter_record;
 334         field->u.perf_counter = perf_field;
 335         lttng_context_update(*ctx);
 336
 337         wrapper_vmalloc_sync_all();
 338         return 0;
 339
 340 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
 341 cpuhp_online_error:
 342         {
 343                 int remove_ret;
 344
 345                 remove_ret = cpuhp_state_remove_instance(lttng_hp_prepare,
 346                                 &perf_field->cpuhp_prepare.node);
 347                 WARN_ON(remove_ret);
 348         }
 349 cpuhp_prepare_error:
 350 #else   /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
 351 counter_busy:
 352 counter_error:
 353         {
 354                 int cpu;
 355
 356                 for_each_online_cpu(cpu) {
 357                         if (events[cpu] && !IS_ERR(events[cpu]))
 358                                 perf_event_release_kernel(events[cpu]);
 359                 }
 360                 put_online_cpus();
 361 #ifdef CONFIG_HOTPLUG_CPU
 362                 unregister_cpu_notifier(&perf_field->nb);
 363 #endif
 364         }
 365 #endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0)) */
 366 find_error:
 367         lttng_remove_context_field(ctx, field);
 368 append_context_error:
 369         kfree(name_alloc);
 370 name_alloc_error:
 371         kfree(perf_field);
 372 error_alloc_perf_field:
 373         kfree(attr);
 374 error_attr:
 375         kfree(events);
 376         return ret;
 377 }