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