kernel/trace/trace_syscalls.c

   1 #include <trace/syscall.h>
   2 #include <trace/events/syscalls.h>
   3 #include <linux/slab.h>
   4 #include <linux/kernel.h>
   5 #include <linux/module.h>       /* for MODULE_NAME_LEN via KSYM_SYMBOL_LEN */
   6 #include <linux/ftrace.h>
   7 #include <linux/perf_event.h>
   8 #include <asm/syscall.h>
   9
  10 #include "trace_output.h"
  11 #include "trace.h"
  12
  13 static DEFINE_MUTEX(syscall_trace_lock);
  14 static int sys_refcount_enter;
  15 static int sys_refcount_exit;
  16 static DECLARE_BITMAP(enabled_enter_syscalls, NR_syscalls);
  17 static DECLARE_BITMAP(enabled_exit_syscalls, NR_syscalls);
  18
  19 static int syscall_enter_register(struct ftrace_event_call *event,
  20                                  enum trace_reg type, void *data);
  21 static int syscall_exit_register(struct ftrace_event_call *event,
  22                                  enum trace_reg type, void *data);
  23
  24 static struct list_head *
  25 syscall_get_enter_fields(struct ftrace_event_call *call)
  26 {
  27         struct syscall_metadata *entry = call->data;
  28
  29         return &entry->enter_fields;
  30 }
  31
  32 extern struct syscall_metadata *__start_syscalls_metadata[];
  33 extern struct syscall_metadata *__stop_syscalls_metadata[];
  34
  35 static struct syscall_metadata **syscalls_metadata;
  36
  37 #ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
  38 static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
  39 {
  40         /*
  41          * Only compare after the "sys" prefix. Archs that use
  42          * syscall wrappers may have syscalls symbols aliases prefixed
  43          * with "SyS" instead of "sys", leading to an unwanted
  44          * mismatch.
  45          */
  46         return !strcmp(sym + 3, name + 3);
  47 }
  48 #endif
  49
  50 static __init struct syscall_metadata *
  51 find_syscall_meta(unsigned long syscall)
  52 {
  53         struct syscall_metadata **start;
  54         struct syscall_metadata **stop;
  55         char str[KSYM_SYMBOL_LEN];
  56
  57
  58         start = __start_syscalls_metadata;
  59         stop = __stop_syscalls_metadata;
  60         kallsyms_lookup(syscall, NULL, NULL, NULL, str);
  61
  62         if (arch_syscall_match_sym_name(str, "sys_ni_syscall"))
  63                 return NULL;
  64
  65         for ( ; start < stop; start++) {
  66                 if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name))
  67                         return *start;
  68         }
  69         return NULL;
  70 }
  71
  72 static struct syscall_metadata *syscall_nr_to_meta(int nr)
  73 {
  74         if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
  75                 return NULL;
  76
  77         return syscalls_metadata[nr];
  78 }
  79
  80 enum print_line_t
  81 print_syscall_enter(struct trace_iterator *iter, int flags,
  82                     struct trace_event *event)
  83 {
  84         struct trace_seq *s = &iter->seq;
  85         struct trace_entry *ent = iter->ent;
  86         struct syscall_trace_enter *trace;
  87         struct syscall_metadata *entry;
  88         int i, ret, syscall;
  89
  90         trace = (typeof(trace))ent;
  91         syscall = trace->nr;
  92         entry = syscall_nr_to_meta(syscall);
  93
  94         if (!entry)
  95                 goto end;
  96
  97         if (entry->enter_event->event.type != ent->type) {
  98                 WARN_ON_ONCE(1);
  99                 goto end;
 100         }
 101
 102         ret = trace_seq_printf(s, "%s(", entry->name);
 103         if (!ret)
 104                 return TRACE_TYPE_PARTIAL_LINE;
 105
 106         for (i = 0; i < entry->nb_args; i++) {
 107                 /* parameter types */
 108                 if (trace_flags & TRACE_ITER_VERBOSE) {
 109                         ret = trace_seq_printf(s, "%s ", entry->types[i]);
 110                         if (!ret)
 111                                 return TRACE_TYPE_PARTIAL_LINE;
 112                 }
 113                 /* parameter values */
 114                 ret = trace_seq_printf(s, "%s: %lx%s", entry->args[i],
 115                                        trace->args[i],
 116                                        i == entry->nb_args - 1 ? "" : ", ");
 117                 if (!ret)
 118                         return TRACE_TYPE_PARTIAL_LINE;
 119         }
 120
 121         ret = trace_seq_putc(s, ')');
 122         if (!ret)
 123                 return TRACE_TYPE_PARTIAL_LINE;
 124
 125 end:
 126         ret =  trace_seq_putc(s, '\n');
 127         if (!ret)
 128                 return TRACE_TYPE_PARTIAL_LINE;
 129
 130         return TRACE_TYPE_HANDLED;
 131 }
 132
 133 enum print_line_t
 134 print_syscall_exit(struct trace_iterator *iter, int flags,
 135                    struct trace_event *event)
 136 {
 137         struct trace_seq *s = &iter->seq;
 138         struct trace_entry *ent = iter->ent;
 139         struct syscall_trace_exit *trace;
 140         int syscall;
 141         struct syscall_metadata *entry;
 142         int ret;
 143
 144         trace = (typeof(trace))ent;
 145         syscall = trace->nr;
 146         entry = syscall_nr_to_meta(syscall);
 147
 148         if (!entry) {
 149                 trace_seq_printf(s, "\n");
 150                 return TRACE_TYPE_HANDLED;
 151         }
 152
 153         if (entry->exit_event->event.type != ent->type) {
 154                 WARN_ON_ONCE(1);
 155                 return TRACE_TYPE_UNHANDLED;
 156         }
 157
 158         ret = trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
 159                                 trace->ret);
 160         if (!ret)
 161                 return TRACE_TYPE_PARTIAL_LINE;
 162
 163         return TRACE_TYPE_HANDLED;
 164 }
 165
 166 extern char *__bad_type_size(void);
 167
 168 #define SYSCALL_FIELD(type, name)                                       \
 169         sizeof(type) != sizeof(trace.name) ?                            \
 170                 __bad_type_size() :                                     \
 171                 #type, #name, offsetof(typeof(trace), name),            \
 172                 sizeof(trace.name), is_signed_type(type)
 173
 174 static
 175 int  __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
 176 {
 177         int i;
 178         int pos = 0;
 179
 180         /* When len=0, we just calculate the needed length */
 181 #define LEN_OR_ZERO (len ? len - pos : 0)
 182
 183         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 184         for (i = 0; i < entry->nb_args; i++) {
 185                 pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
 186                                 entry->args[i], sizeof(unsigned long),
 187                                 i == entry->nb_args - 1 ? "" : ", ");
 188         }
 189         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 190
 191         for (i = 0; i < entry->nb_args; i++) {
 192                 pos += snprintf(buf + pos, LEN_OR_ZERO,
 193                                 ", ((unsigned long)(REC->%s))", entry->args[i]);
 194         }
 195
 196 #undef LEN_OR_ZERO
 197
 198         /* return the length of print_fmt */
 199         return pos;
 200 }
 201
 202 static int set_syscall_print_fmt(struct ftrace_event_call *call)
 203 {
 204         char *print_fmt;
 205         int len;
 206         struct syscall_metadata *entry = call->data;
 207
 208         if (entry->enter_event != call) {
 209                 call->print_fmt = "\"0x%lx\", REC->ret";
 210                 return 0;
 211         }
 212
 213         /* First: called with 0 length to calculate the needed length */
 214         len = __set_enter_print_fmt(entry, NULL, 0);
 215
 216         print_fmt = kmalloc(len + 1, GFP_KERNEL);
 217         if (!print_fmt)
 218                 return -ENOMEM;
 219
 220         /* Second: actually write the @print_fmt */
 221         __set_enter_print_fmt(entry, print_fmt, len + 1);
 222         call->print_fmt = print_fmt;
 223
 224         return 0;
 225 }
 226
 227 static void free_syscall_print_fmt(struct ftrace_event_call *call)
 228 {
 229         struct syscall_metadata *entry = call->data;
 230
 231         if (entry->enter_event == call)
 232                 kfree(call->print_fmt);
 233 }
 234
 235 static int syscall_enter_define_fields(struct ftrace_event_call *call)
 236 {
 237         struct syscall_trace_enter trace;
 238         struct syscall_metadata *meta = call->data;
 239         int ret;
 240         int i;
 241         int offset = offsetof(typeof(trace), args);
 242
 243         ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
 244         if (ret)
 245                 return ret;
 246
 247         for (i = 0; i < meta->nb_args; i++) {
 248                 ret = trace_define_field(call, meta->types[i],
 249                                          meta->args[i], offset,
 250                                          sizeof(unsigned long), 0,
 251                                          FILTER_OTHER);
 252                 offset += sizeof(unsigned long);
 253         }
 254
 255         return ret;
 256 }
 257
 258 static int syscall_exit_define_fields(struct ftrace_event_call *call)
 259 {
 260         struct syscall_trace_exit trace;
 261         int ret;
 262
 263         ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
 264         if (ret)
 265                 return ret;
 266
 267         ret = trace_define_field(call, SYSCALL_FIELD(long, ret),
 268                                  FILTER_OTHER);
 269
 270         return ret;
 271 }
 272
 273 void ftrace_syscall_enter(void *ignore, struct pt_regs *regs, long id)
 274 {
 275         struct syscall_trace_enter *entry;
 276         struct syscall_metadata *sys_data;
 277         struct ring_buffer_event *event;
 278         struct ring_buffer *buffer;
 279         int size;
 280         int syscall_nr;
 281
 282         syscall_nr = syscall_get_nr(current, regs);
 283         if (syscall_nr < 0)
 284                 return;
 285         if (!test_bit(syscall_nr, enabled_enter_syscalls))
 286                 return;
 287
 288         sys_data = syscall_nr_to_meta(syscall_nr);
 289         if (!sys_data)
 290                 return;
 291
 292         size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
 293
 294         event = trace_current_buffer_lock_reserve(&buffer,
 295                         sys_data->enter_event->event.type, size, 0, 0);
 296         if (!event)
 297                 return;
 298
 299         entry = ring_buffer_event_data(event);
 300         entry->nr = syscall_nr;
 301         syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
 302
 303         if (!filter_current_check_discard(buffer, sys_data->enter_event,
 304                                           entry, event))
 305                 trace_current_buffer_unlock_commit(buffer, event, 0, 0);
 306 }
 307
 308 void ftrace_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 309 {
 310         struct syscall_trace_exit *entry;
 311         struct syscall_metadata *sys_data;
 312         struct ring_buffer_event *event;
 313         struct ring_buffer *buffer;
 314         int syscall_nr;
 315
 316         syscall_nr = syscall_get_nr(current, regs);
 317         if (syscall_nr < 0)
 318                 return;
 319         if (!test_bit(syscall_nr, enabled_exit_syscalls))
 320                 return;
 321
 322         sys_data = syscall_nr_to_meta(syscall_nr);
 323         if (!sys_data)
 324                 return;
 325
 326         event = trace_current_buffer_lock_reserve(&buffer,
 327                         sys_data->exit_event->event.type, sizeof(*entry), 0, 0);
 328         if (!event)
 329                 return;
 330
 331         entry = ring_buffer_event_data(event);
 332         entry->nr = syscall_nr;
 333         entry->ret = syscall_get_return_value(current, regs);
 334
 335         if (!filter_current_check_discard(buffer, sys_data->exit_event,
 336                                           entry, event))
 337                 trace_current_buffer_unlock_commit(buffer, event, 0, 0);
 338 }
 339
 340 int reg_event_syscall_enter(struct ftrace_event_call *call)
 341 {
 342         int ret = 0;
 343         int num;
 344
 345         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 346         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 347                 return -ENOSYS;
 348         mutex_lock(&syscall_trace_lock);
 349         if (!sys_refcount_enter)
 350                 ret = register_trace_sys_enter(ftrace_syscall_enter, NULL);
 351         if (!ret) {
 352                 set_bit(num, enabled_enter_syscalls);
 353                 sys_refcount_enter++;
 354         }
 355         mutex_unlock(&syscall_trace_lock);
 356         return ret;
 357 }
 358
 359 void unreg_event_syscall_enter(struct ftrace_event_call *call)
 360 {
 361         int num;
 362
 363         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 364         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 365                 return;
 366         mutex_lock(&syscall_trace_lock);
 367         sys_refcount_enter--;
 368         clear_bit(num, enabled_enter_syscalls);
 369         if (!sys_refcount_enter)
 370                 unregister_trace_sys_enter(ftrace_syscall_enter, NULL);
 371         mutex_unlock(&syscall_trace_lock);
 372 }
 373
 374 int reg_event_syscall_exit(struct ftrace_event_call *call)
 375 {
 376         int ret = 0;
 377         int num;
 378
 379         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 380         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 381                 return -ENOSYS;
 382         mutex_lock(&syscall_trace_lock);
 383         if (!sys_refcount_exit)
 384                 ret = register_trace_sys_exit(ftrace_syscall_exit, NULL);
 385         if (!ret) {
 386                 set_bit(num, enabled_exit_syscalls);
 387                 sys_refcount_exit++;
 388         }
 389         mutex_unlock(&syscall_trace_lock);
 390         return ret;
 391 }
 392
 393 void unreg_event_syscall_exit(struct ftrace_event_call *call)
 394 {
 395         int num;
 396
 397         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 398         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 399                 return;
 400         mutex_lock(&syscall_trace_lock);
 401         sys_refcount_exit--;
 402         clear_bit(num, enabled_exit_syscalls);
 403         if (!sys_refcount_exit)
 404                 unregister_trace_sys_exit(ftrace_syscall_exit, NULL);
 405         mutex_unlock(&syscall_trace_lock);
 406 }
 407
 408 static int init_syscall_trace(struct ftrace_event_call *call)
 409 {
 410         int id;
 411         int num;
 412
 413         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 414         if (num < 0 || num >= NR_syscalls) {
 415                 pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
 416                                 ((struct syscall_metadata *)call->data)->name);
 417                 return -ENOSYS;
 418         }
 419
 420         if (set_syscall_print_fmt(call) < 0)
 421                 return -ENOMEM;
 422
 423         id = trace_event_raw_init(call);
 424
 425         if (id < 0) {
 426                 free_syscall_print_fmt(call);
 427                 return id;
 428         }
 429
 430         return id;
 431 }
 432
 433 struct trace_event_functions enter_syscall_print_funcs = {
 434         .trace          = print_syscall_enter,
 435 };
 436
 437 struct trace_event_functions exit_syscall_print_funcs = {
 438         .trace          = print_syscall_exit,
 439 };
 440
 441 struct ftrace_event_class event_class_syscall_enter = {
 442         .system         = "syscalls",
 443         .reg            = syscall_enter_register,
 444         .define_fields  = syscall_enter_define_fields,
 445         .get_fields     = syscall_get_enter_fields,
 446         .raw_init       = init_syscall_trace,
 447 };
 448
 449 struct ftrace_event_class event_class_syscall_exit = {
 450         .system         = "syscalls",
 451         .reg            = syscall_exit_register,
 452         .define_fields  = syscall_exit_define_fields,
 453         .fields         = LIST_HEAD_INIT(event_class_syscall_exit.fields),
 454         .raw_init       = init_syscall_trace,
 455 };
 456
 457 unsigned long __init __weak arch_syscall_addr(int nr)
 458 {
 459         return (unsigned long)sys_call_table[nr];
 460 }
 461
 462 int __init init_ftrace_syscalls(void)
 463 {
 464         struct syscall_metadata *meta;
 465         unsigned long addr;
 466         int i;
 467
 468         syscalls_metadata = kcalloc(NR_syscalls, sizeof(*syscalls_metadata),
 469                                     GFP_KERNEL);
 470         if (!syscalls_metadata) {
 471                 WARN_ON(1);
 472                 return -ENOMEM;
 473         }
 474
 475         for (i = 0; i < NR_syscalls; i++) {
 476                 addr = arch_syscall_addr(i);
 477                 meta = find_syscall_meta(addr);
 478                 if (!meta)
 479                         continue;
 480
 481                 meta->syscall_nr = i;
 482                 syscalls_metadata[i] = meta;
 483         }
 484
 485         return 0;
 486 }
 487 early_initcall(init_ftrace_syscalls);
 488
 489 #ifdef CONFIG_PERF_EVENTS
 490
 491 static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
 492 static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
 493 static int sys_perf_refcount_enter;
 494 static int sys_perf_refcount_exit;
 495
 496 static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
 497 {
 498         struct syscall_metadata *sys_data;
 499         struct syscall_trace_enter *rec;
 500         struct hlist_head *head;
 501         int syscall_nr;
 502         int rctx;
 503         int size;
 504
 505         syscall_nr = syscall_get_nr(current, regs);
 506         if (syscall_nr < 0)
 507                 return;
 508         if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
 509                 return;
 510
 511         sys_data = syscall_nr_to_meta(syscall_nr);
 512         if (!sys_data)
 513                 return;
 514
 515         /* get the size after alignment with the u32 buffer size field */
 516         size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
 517         size = ALIGN(size + sizeof(u32), sizeof(u64));
 518         size -= sizeof(u32);
 519
 520         if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
 521                       "perf buffer not large enough"))
 522                 return;
 523
 524         rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size,
 525                                 sys_data->enter_event->event.type, regs, &rctx);
 526         if (!rec)
 527                 return;
 528
 529         rec->nr = syscall_nr;
 530         syscall_get_arguments(current, regs, 0, sys_data->nb_args,
 531                                (unsigned long *)&rec->args);
 532
 533         head = this_cpu_ptr(sys_data->enter_event->perf_events);
 534         perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 535 }
 536
 537 static int perf_sysenter_enable(struct ftrace_event_call *call)
 538 {
 539         int ret = 0;
 540         int num;
 541
 542         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 543
 544         mutex_lock(&syscall_trace_lock);
 545         if (!sys_perf_refcount_enter)
 546                 ret = register_trace_sys_enter(perf_syscall_enter, NULL);
 547         if (ret) {
 548                 pr_info("event trace: Could not activate"
 549                                 "syscall entry trace point");
 550         } else {
 551                 set_bit(num, enabled_perf_enter_syscalls);
 552                 sys_perf_refcount_enter++;
 553         }
 554         mutex_unlock(&syscall_trace_lock);
 555         return ret;
 556 }
 557
 558 static void perf_sysenter_disable(struct ftrace_event_call *call)
 559 {
 560         int num;
 561
 562         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 563
 564         mutex_lock(&syscall_trace_lock);
 565         sys_perf_refcount_enter--;
 566         clear_bit(num, enabled_perf_enter_syscalls);
 567         if (!sys_perf_refcount_enter)
 568                 unregister_trace_sys_enter(perf_syscall_enter, NULL);
 569         mutex_unlock(&syscall_trace_lock);
 570 }
 571
 572 static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 573 {
 574         struct syscall_metadata *sys_data;
 575         struct syscall_trace_exit *rec;
 576         struct hlist_head *head;
 577         int syscall_nr;
 578         int rctx;
 579         int size;
 580
 581         syscall_nr = syscall_get_nr(current, regs);
 582         if (syscall_nr < 0)
 583                 return;
 584         if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
 585                 return;
 586
 587         sys_data = syscall_nr_to_meta(syscall_nr);
 588         if (!sys_data)
 589                 return;
 590
 591         /* We can probably do that at build time */
 592         size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
 593         size -= sizeof(u32);
 594
 595         /*
 596          * Impossible, but be paranoid with the future
 597          * How to put this check outside runtime?
 598          */
 599         if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
 600                 "exit event has grown above perf buffer size"))
 601                 return;
 602
 603         rec = (struct syscall_trace_exit *)perf_trace_buf_prepare(size,
 604                                 sys_data->exit_event->event.type, regs, &rctx);
 605         if (!rec)
 606                 return;
 607
 608         rec->nr = syscall_nr;
 609         rec->ret = syscall_get_return_value(current, regs);
 610
 611         head = this_cpu_ptr(sys_data->exit_event->perf_events);
 612         perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 613 }
 614
 615 static int perf_sysexit_enable(struct ftrace_event_call *call)
 616 {
 617         int ret = 0;
 618         int num;
 619
 620         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 621
 622         mutex_lock(&syscall_trace_lock);
 623         if (!sys_perf_refcount_exit)
 624                 ret = register_trace_sys_exit(perf_syscall_exit, NULL);
 625         if (ret) {
 626                 pr_info("event trace: Could not activate"
 627                                 "syscall exit trace point");
 628         } else {
 629                 set_bit(num, enabled_perf_exit_syscalls);
 630                 sys_perf_refcount_exit++;
 631         }
 632         mutex_unlock(&syscall_trace_lock);
 633         return ret;
 634 }
 635
 636 static void perf_sysexit_disable(struct ftrace_event_call *call)
 637 {
 638         int num;
 639
 640         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 641
 642         mutex_lock(&syscall_trace_lock);
 643         sys_perf_refcount_exit--;
 644         clear_bit(num, enabled_perf_exit_syscalls);
 645         if (!sys_perf_refcount_exit)
 646                 unregister_trace_sys_exit(perf_syscall_exit, NULL);
 647         mutex_unlock(&syscall_trace_lock);
 648 }
 649
 650 #endif /* CONFIG_PERF_EVENTS */
 651
 652 static int syscall_enter_register(struct ftrace_event_call *event,
 653                                  enum trace_reg type, void *data)
 654 {
 655         switch (type) {
 656         case TRACE_REG_REGISTER:
 657                 return reg_event_syscall_enter(event);
 658         case TRACE_REG_UNREGISTER:
 659                 unreg_event_syscall_enter(event);
 660                 return 0;
 661
 662 #ifdef CONFIG_PERF_EVENTS
 663         case TRACE_REG_PERF_REGISTER:
 664                 return perf_sysenter_enable(event);
 665         case TRACE_REG_PERF_UNREGISTER:
 666                 perf_sysenter_disable(event);
 667                 return 0;
 668         case TRACE_REG_PERF_OPEN:
 669         case TRACE_REG_PERF_CLOSE:
 670         case TRACE_REG_PERF_ADD:
 671         case TRACE_REG_PERF_DEL:
 672                 return 0;
 673 #endif
 674         }
 675         return 0;
 676 }
 677
 678 static int syscall_exit_register(struct ftrace_event_call *event,
 679                                  enum trace_reg type, void *data)
 680 {
 681         switch (type) {
 682         case TRACE_REG_REGISTER:
 683                 return reg_event_syscall_exit(event);
 684         case TRACE_REG_UNREGISTER:
 685                 unreg_event_syscall_exit(event);
 686                 return 0;
 687
 688 #ifdef CONFIG_PERF_EVENTS
 689         case TRACE_REG_PERF_REGISTER:
 690                 return perf_sysexit_enable(event);
 691         case TRACE_REG_PERF_UNREGISTER:
 692                 perf_sysexit_disable(event);
 693                 return 0;
 694         case TRACE_REG_PERF_OPEN:
 695         case TRACE_REG_PERF_CLOSE:
 696         case TRACE_REG_PERF_ADD:
 697         case TRACE_REG_PERF_DEL:
 698                 return 0;
 699 #endif
 700         }
 701         return 0;
 702 }