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