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         unsigned long irq_flags;
 307         int pc;
 308         int size;
 309         int syscall_nr;
 310
 311         syscall_nr = syscall_get_nr(current, regs);
 312         if (syscall_nr < 0)
 313                 return;
 314         if (!test_bit(syscall_nr, enabled_enter_syscalls))
 315                 return;
 316
 317         sys_data = syscall_nr_to_meta(syscall_nr);
 318         if (!sys_data)
 319                 return;
 320
 321         size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
 322
 323         local_save_flags(irq_flags);
 324         pc = preempt_count();
 325
 326         event = trace_current_buffer_lock_reserve(&buffer,
 327                         sys_data->enter_event->event.type, size, irq_flags, pc);
 328         if (!event)
 329                 return;
 330
 331         entry = ring_buffer_event_data(event);
 332         entry->nr = syscall_nr;
 333         syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
 334
 335         if (!filter_current_check_discard(buffer, sys_data->enter_event,
 336                                           entry, event))
 337                 trace_current_buffer_unlock_commit(buffer, event,
 338                                                    irq_flags, pc);
 339 }
 340
 341 void ftrace_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 342 {
 343         struct syscall_trace_exit *entry;
 344         struct syscall_metadata *sys_data;
 345         struct ring_buffer_event *event;
 346         struct ring_buffer *buffer;
 347         unsigned long irq_flags;
 348         int pc;
 349         int syscall_nr;
 350
 351         syscall_nr = syscall_get_nr(current, regs);
 352         if (syscall_nr < 0)
 353                 return;
 354         if (!test_bit(syscall_nr, enabled_exit_syscalls))
 355                 return;
 356
 357         sys_data = syscall_nr_to_meta(syscall_nr);
 358         if (!sys_data)
 359                 return;
 360
 361         local_save_flags(irq_flags);
 362         pc = preempt_count();
 363
 364         event = trace_current_buffer_lock_reserve(&buffer,
 365                         sys_data->exit_event->event.type, sizeof(*entry),
 366                         irq_flags, pc);
 367         if (!event)
 368                 return;
 369
 370         entry = ring_buffer_event_data(event);
 371         entry->nr = syscall_nr;
 372         entry->ret = syscall_get_return_value(current, regs);
 373
 374         if (!filter_current_check_discard(buffer, sys_data->exit_event,
 375                                           entry, event))
 376                 trace_current_buffer_unlock_commit(buffer, event,
 377                                                    irq_flags, pc);
 378 }
 379
 380 int reg_event_syscall_enter(struct ftrace_event_call *call)
 381 {
 382         int ret = 0;
 383         int num;
 384
 385         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 386         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 387                 return -ENOSYS;
 388         mutex_lock(&syscall_trace_lock);
 389         if (!sys_refcount_enter)
 390                 ret = register_trace_sys_enter(ftrace_syscall_enter, NULL);
 391         if (!ret) {
 392                 set_bit(num, enabled_enter_syscalls);
 393                 sys_refcount_enter++;
 394         }
 395         mutex_unlock(&syscall_trace_lock);
 396         return ret;
 397 }
 398
 399 void unreg_event_syscall_enter(struct ftrace_event_call *call)
 400 {
 401         int num;
 402
 403         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 404         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 405                 return;
 406         mutex_lock(&syscall_trace_lock);
 407         sys_refcount_enter--;
 408         clear_bit(num, enabled_enter_syscalls);
 409         if (!sys_refcount_enter)
 410                 unregister_trace_sys_enter(ftrace_syscall_enter, NULL);
 411         mutex_unlock(&syscall_trace_lock);
 412 }
 413
 414 int reg_event_syscall_exit(struct ftrace_event_call *call)
 415 {
 416         int ret = 0;
 417         int num;
 418
 419         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 420         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 421                 return -ENOSYS;
 422         mutex_lock(&syscall_trace_lock);
 423         if (!sys_refcount_exit)
 424                 ret = register_trace_sys_exit(ftrace_syscall_exit, NULL);
 425         if (!ret) {
 426                 set_bit(num, enabled_exit_syscalls);
 427                 sys_refcount_exit++;
 428         }
 429         mutex_unlock(&syscall_trace_lock);
 430         return ret;
 431 }
 432
 433 void unreg_event_syscall_exit(struct ftrace_event_call *call)
 434 {
 435         int num;
 436
 437         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 438         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 439                 return;
 440         mutex_lock(&syscall_trace_lock);
 441         sys_refcount_exit--;
 442         clear_bit(num, enabled_exit_syscalls);
 443         if (!sys_refcount_exit)
 444                 unregister_trace_sys_exit(ftrace_syscall_exit, NULL);
 445         mutex_unlock(&syscall_trace_lock);
 446 }
 447
 448 int init_syscall_trace(struct ftrace_event_call *call)
 449 {
 450         int id;
 451         int num;
 452
 453         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 454         if (num < 0 || num >= NR_syscalls) {
 455                 pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
 456                                 ((struct syscall_metadata *)call->data)->name);
 457                 return -ENOSYS;
 458         }
 459
 460         if (set_syscall_print_fmt(call) < 0)
 461                 return -ENOMEM;
 462
 463         id = trace_event_raw_init(call);
 464
 465         if (id < 0) {
 466                 free_syscall_print_fmt(call);
 467                 return id;
 468         }
 469
 470         return id;
 471 }
 472
 473 unsigned long __init __weak arch_syscall_addr(int nr)
 474 {
 475         return (unsigned long)sys_call_table[nr];
 476 }
 477
 478 int __init init_ftrace_syscalls(void)
 479 {
 480         struct syscall_metadata *meta;
 481         unsigned long addr;
 482         int i;
 483
 484         syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
 485                                         NR_syscalls, GFP_KERNEL);
 486         if (!syscalls_metadata) {
 487                 WARN_ON(1);
 488                 return -ENOMEM;
 489         }
 490
 491         for (i = 0; i < NR_syscalls; i++) {
 492                 addr = arch_syscall_addr(i);
 493                 meta = find_syscall_meta(addr);
 494                 if (!meta)
 495                         continue;
 496
 497                 meta->syscall_nr = i;
 498                 syscalls_metadata[i] = meta;
 499         }
 500
 501         return 0;
 502 }
 503 core_initcall(init_ftrace_syscalls);
 504
 505 #ifdef CONFIG_PERF_EVENTS
 506
 507 static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
 508 static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
 509 static int sys_perf_refcount_enter;
 510 static int sys_perf_refcount_exit;
 511
 512 static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
 513 {
 514         struct syscall_metadata *sys_data;
 515         struct syscall_trace_enter *rec;
 516         struct hlist_head *head;
 517         int syscall_nr;
 518         int rctx;
 519         int size;
 520
 521         syscall_nr = syscall_get_nr(current, regs);
 522         if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
 523                 return;
 524
 525         sys_data = syscall_nr_to_meta(syscall_nr);
 526         if (!sys_data)
 527                 return;
 528
 529         /* get the size after alignment with the u32 buffer size field */
 530         size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
 531         size = ALIGN(size + sizeof(u32), sizeof(u64));
 532         size -= sizeof(u32);
 533
 534         if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
 535                       "perf buffer not large enough"))
 536                 return;
 537
 538         rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size,
 539                                 sys_data->enter_event->event.type, regs, &rctx);
 540         if (!rec)
 541                 return;
 542
 543         rec->nr = syscall_nr;
 544         syscall_get_arguments(current, regs, 0, sys_data->nb_args,
 545                                (unsigned long *)&rec->args);
 546
 547         head = this_cpu_ptr(sys_data->enter_event->perf_events);
 548         perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);
 549 }
 550
 551 int perf_sysenter_enable(struct ftrace_event_call *call)
 552 {
 553         int ret = 0;
 554         int num;
 555
 556         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 557
 558         mutex_lock(&syscall_trace_lock);
 559         if (!sys_perf_refcount_enter)
 560                 ret = register_trace_sys_enter(perf_syscall_enter, NULL);
 561         if (ret) {
 562                 pr_info("event trace: Could not activate"
 563                                 "syscall entry trace point");
 564         } else {
 565                 set_bit(num, enabled_perf_enter_syscalls);
 566                 sys_perf_refcount_enter++;
 567         }
 568         mutex_unlock(&syscall_trace_lock);
 569         return ret;
 570 }
 571
 572 void perf_sysenter_disable(struct ftrace_event_call *call)
 573 {
 574         int num;
 575
 576         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 577
 578         mutex_lock(&syscall_trace_lock);
 579         sys_perf_refcount_enter--;
 580         clear_bit(num, enabled_perf_enter_syscalls);
 581         if (!sys_perf_refcount_enter)
 582                 unregister_trace_sys_enter(perf_syscall_enter, NULL);
 583         mutex_unlock(&syscall_trace_lock);
 584 }
 585
 586 static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 587 {
 588         struct syscall_metadata *sys_data;
 589         struct syscall_trace_exit *rec;
 590         struct hlist_head *head;
 591         int syscall_nr;
 592         int rctx;
 593         int size;
 594
 595         syscall_nr = syscall_get_nr(current, regs);
 596         if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
 597                 return;
 598
 599         sys_data = syscall_nr_to_meta(syscall_nr);
 600         if (!sys_data)
 601                 return;
 602
 603         /* We can probably do that at build time */
 604         size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
 605         size -= sizeof(u32);
 606
 607         /*
 608          * Impossible, but be paranoid with the future
 609          * How to put this check outside runtime?
 610          */
 611         if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
 612                 "exit event has grown above perf buffer size"))
 613                 return;
 614
 615         rec = (struct syscall_trace_exit *)perf_trace_buf_prepare(size,
 616                                 sys_data->exit_event->event.type, regs, &rctx);
 617         if (!rec)
 618                 return;
 619
 620         rec->nr = syscall_nr;
 621         rec->ret = syscall_get_return_value(current, regs);
 622
 623         head = this_cpu_ptr(sys_data->exit_event->perf_events);
 624         perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head);
 625 }
 626
 627 int perf_sysexit_enable(struct ftrace_event_call *call)
 628 {
 629         int ret = 0;
 630         int num;
 631
 632         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 633
 634         mutex_lock(&syscall_trace_lock);
 635         if (!sys_perf_refcount_exit)
 636                 ret = register_trace_sys_exit(perf_syscall_exit, NULL);
 637         if (ret) {
 638                 pr_info("event trace: Could not activate"
 639                                 "syscall exit trace point");
 640         } else {
 641                 set_bit(num, enabled_perf_exit_syscalls);
 642                 sys_perf_refcount_exit++;
 643         }
 644         mutex_unlock(&syscall_trace_lock);
 645         return ret;
 646 }
 647
 648 void perf_sysexit_disable(struct ftrace_event_call *call)
 649 {
 650         int num;
 651
 652         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 653
 654         mutex_lock(&syscall_trace_lock);
 655         sys_perf_refcount_exit--;
 656         clear_bit(num, enabled_perf_exit_syscalls);
 657         if (!sys_perf_refcount_exit)
 658                 unregister_trace_sys_exit(perf_syscall_exit, NULL);
 659         mutex_unlock(&syscall_trace_lock);
 660 }
 661
 662 #endif /* CONFIG_PERF_EVENTS */
 663
 664 static int syscall_enter_register(struct ftrace_event_call *event,
 665                                  enum trace_reg type)
 666 {
 667         switch (type) {
 668         case TRACE_REG_REGISTER:
 669                 return reg_event_syscall_enter(event);
 670         case TRACE_REG_UNREGISTER:
 671                 unreg_event_syscall_enter(event);
 672                 return 0;
 673
 674 #ifdef CONFIG_PERF_EVENTS
 675         case TRACE_REG_PERF_REGISTER:
 676                 return perf_sysenter_enable(event);
 677         case TRACE_REG_PERF_UNREGISTER:
 678                 perf_sysenter_disable(event);
 679                 return 0;
 680 #endif
 681         }
 682         return 0;
 683 }
 684
 685 static int syscall_exit_register(struct ftrace_event_call *event,
 686                                  enum trace_reg type)
 687 {
 688         switch (type) {
 689         case TRACE_REG_REGISTER:
 690                 return reg_event_syscall_exit(event);
 691         case TRACE_REG_UNREGISTER:
 692                 unreg_event_syscall_exit(event);
 693                 return 0;
 694
 695 #ifdef CONFIG_PERF_EVENTS
 696         case TRACE_REG_PERF_REGISTER:
 697                 return perf_sysexit_enable(event);
 698         case TRACE_REG_PERF_UNREGISTER:
 699                 perf_sysexit_disable(event);
 700                 return 0;
 701 #endif
 702         }
 703         return 0;
 704 }