kernel/kernel/trace/trace_syscalls.c

   1 #include <trace/syscall.h>
   2 #include <trace/events/syscalls.h>
   3 #include <linux/syscalls.h>
   4 #include <linux/slab.h>
   5 #include <linux/kernel.h>
   6 #include <linux/module.h>       /* for MODULE_NAME_LEN via KSYM_SYMBOL_LEN */
   7 #include <linux/ftrace.h>
   8 #include <linux/perf_event.h>
   9 #include <asm/syscall.h>
  10
  11 #include "trace_output.h"
  12 #include "trace.h"
  13
  14 static DEFINE_MUTEX(syscall_trace_lock);
  15
  16 static int syscall_enter_register(struct trace_event_call *event,
  17                                  enum trace_reg type, void *data);
  18 static int syscall_exit_register(struct trace_event_call *event,
  19                                  enum trace_reg type, void *data);
  20
  21 static struct list_head *
  22 syscall_get_enter_fields(struct trace_event_call *call)
  23 {
  24         struct syscall_metadata *entry = call->data;
  25
  26         return &entry->enter_fields;
  27 }
  28
  29 extern struct syscall_metadata *__start_syscalls_metadata[];
  30 extern struct syscall_metadata *__stop_syscalls_metadata[];
  31
  32 static struct syscall_metadata **syscalls_metadata;
  33
  34 #ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
  35 static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
  36 {
  37         /*
  38          * Only compare after the "sys" prefix. Archs that use
  39          * syscall wrappers may have syscalls symbols aliases prefixed
  40          * with ".SyS" or ".sys" instead of "sys", leading to an unwanted
  41          * mismatch.
  42          */
  43         return !strcmp(sym + 3, name + 3);
  44 }
  45 #endif
  46
  47 #ifdef ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
  48 /*
  49  * Some architectures that allow for 32bit applications
  50  * to run on a 64bit kernel, do not map the syscalls for
  51  * the 32bit tasks the same as they do for 64bit tasks.
  52  *
  53  *     *cough*x86*cough*
  54  *
  55  * In such a case, instead of reporting the wrong syscalls,
  56  * simply ignore them.
  57  *
  58  * For an arch to ignore the compat syscalls it needs to
  59  * define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS as well as
  60  * define the function arch_trace_is_compat_syscall() to let
  61  * the tracing system know that it should ignore it.
  62  */
  63 static int
  64 trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs)
  65 {
  66         if (unlikely(arch_trace_is_compat_syscall(regs)))
  67                 return -1;
  68
  69         return syscall_get_nr(task, regs);
  70 }
  71 #else
  72 static inline int
  73 trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs)
  74 {
  75         return syscall_get_nr(task, regs);
  76 }
  77 #endif /* ARCH_TRACE_IGNORE_COMPAT_SYSCALLS */
  78
  79 static __init struct syscall_metadata *
  80 find_syscall_meta(unsigned long syscall)
  81 {
  82         struct syscall_metadata **start;
  83         struct syscall_metadata **stop;
  84         char str[KSYM_SYMBOL_LEN];
  85
  86
  87         start = __start_syscalls_metadata;
  88         stop = __stop_syscalls_metadata;
  89         kallsyms_lookup(syscall, NULL, NULL, NULL, str);
  90
  91         if (arch_syscall_match_sym_name(str, "sys_ni_syscall"))
  92                 return NULL;
  93
  94         for ( ; start < stop; start++) {
  95                 if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name))
  96                         return *start;
  97         }
  98         return NULL;
  99 }
 100
 101 static struct syscall_metadata *syscall_nr_to_meta(int nr)
 102 {
 103         if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
 104                 return NULL;
 105
 106         return syscalls_metadata[nr];
 107 }
 108
 109 static enum print_line_t
 110 print_syscall_enter(struct trace_iterator *iter, int flags,
 111                     struct trace_event *event)
 112 {
 113         struct trace_array *tr = iter->tr;
 114         struct trace_seq *s = &iter->seq;
 115         struct trace_entry *ent = iter->ent;
 116         struct syscall_trace_enter *trace;
 117         struct syscall_metadata *entry;
 118         int i, syscall;
 119
 120         trace = (typeof(trace))ent;
 121         syscall = trace->nr;
 122         entry = syscall_nr_to_meta(syscall);
 123
 124         if (!entry)
 125                 goto end;
 126
 127         if (entry->enter_event->event.type != ent->type) {
 128                 WARN_ON_ONCE(1);
 129                 goto end;
 130         }
 131
 132         trace_seq_printf(s, "%s(", entry->name);
 133
 134         for (i = 0; i < entry->nb_args; i++) {
 135
 136                 if (trace_seq_has_overflowed(s))
 137                         goto end;
 138
 139                 /* parameter types */
 140                 if (tr->trace_flags & TRACE_ITER_VERBOSE)
 141                         trace_seq_printf(s, "%s ", entry->types[i]);
 142
 143                 /* parameter values */
 144                 trace_seq_printf(s, "%s: %lx%s", entry->args[i],
 145                                  trace->args[i],
 146                                  i == entry->nb_args - 1 ? "" : ", ");
 147         }
 148
 149         trace_seq_putc(s, ')');
 150 end:
 151         trace_seq_putc(s, '\n');
 152
 153         return trace_handle_return(s);
 154 }
 155
 156 static enum print_line_t
 157 print_syscall_exit(struct trace_iterator *iter, int flags,
 158                    struct trace_event *event)
 159 {
 160         struct trace_seq *s = &iter->seq;
 161         struct trace_entry *ent = iter->ent;
 162         struct syscall_trace_exit *trace;
 163         int syscall;
 164         struct syscall_metadata *entry;
 165
 166         trace = (typeof(trace))ent;
 167         syscall = trace->nr;
 168         entry = syscall_nr_to_meta(syscall);
 169
 170         if (!entry) {
 171                 trace_seq_putc(s, '\n');
 172                 goto out;
 173         }
 174
 175         if (entry->exit_event->event.type != ent->type) {
 176                 WARN_ON_ONCE(1);
 177                 return TRACE_TYPE_UNHANDLED;
 178         }
 179
 180         trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
 181                                 trace->ret);
 182
 183  out:
 184         return trace_handle_return(s);
 185 }
 186
 187 extern char *__bad_type_size(void);
 188
 189 #define SYSCALL_FIELD(type, name)                                       \
 190         sizeof(type) != sizeof(trace.name) ?                            \
 191                 __bad_type_size() :                                     \
 192                 #type, #name, offsetof(typeof(trace), name),            \
 193                 sizeof(trace.name), is_signed_type(type)
 194
 195 static int __init
 196 __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
 197 {
 198         int i;
 199         int pos = 0;
 200
 201         /* When len=0, we just calculate the needed length */
 202 #define LEN_OR_ZERO (len ? len - pos : 0)
 203
 204         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 205         for (i = 0; i < entry->nb_args; i++) {
 206                 pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
 207                                 entry->args[i], sizeof(unsigned long),
 208                                 i == entry->nb_args - 1 ? "" : ", ");
 209         }
 210         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 211
 212         for (i = 0; i < entry->nb_args; i++) {
 213                 pos += snprintf(buf + pos, LEN_OR_ZERO,
 214                                 ", ((unsigned long)(REC->%s))", entry->args[i]);
 215         }
 216
 217 #undef LEN_OR_ZERO
 218
 219         /* return the length of print_fmt */
 220         return pos;
 221 }
 222
 223 static int __init set_syscall_print_fmt(struct trace_event_call *call)
 224 {
 225         char *print_fmt;
 226         int len;
 227         struct syscall_metadata *entry = call->data;
 228
 229         if (entry->enter_event != call) {
 230                 call->print_fmt = "\"0x%lx\", REC->ret";
 231                 return 0;
 232         }
 233
 234         /* First: called with 0 length to calculate the needed length */
 235         len = __set_enter_print_fmt(entry, NULL, 0);
 236
 237         print_fmt = kmalloc(len + 1, GFP_KERNEL);
 238         if (!print_fmt)
 239                 return -ENOMEM;
 240
 241         /* Second: actually write the @print_fmt */
 242         __set_enter_print_fmt(entry, print_fmt, len + 1);
 243         call->print_fmt = print_fmt;
 244
 245         return 0;
 246 }
 247
 248 static void __init free_syscall_print_fmt(struct trace_event_call *call)
 249 {
 250         struct syscall_metadata *entry = call->data;
 251
 252         if (entry->enter_event == call)
 253                 kfree(call->print_fmt);
 254 }
 255
 256 static int __init syscall_enter_define_fields(struct trace_event_call *call)
 257 {
 258         struct syscall_trace_enter trace;
 259         struct syscall_metadata *meta = call->data;
 260         int ret;
 261         int i;
 262         int offset = offsetof(typeof(trace), args);
 263
 264         ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
 265         if (ret)
 266                 return ret;
 267
 268         for (i = 0; i < meta->nb_args; i++) {
 269                 ret = trace_define_field(call, meta->types[i],
 270                                          meta->args[i], offset,
 271                                          sizeof(unsigned long), 0,
 272                                          FILTER_OTHER);
 273                 offset += sizeof(unsigned long);
 274         }
 275
 276         return ret;
 277 }
 278
 279 static int __init syscall_exit_define_fields(struct trace_event_call *call)
 280 {
 281         struct syscall_trace_exit trace;
 282         int ret;
 283
 284         ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
 285         if (ret)
 286                 return ret;
 287
 288         ret = trace_define_field(call, SYSCALL_FIELD(long, ret),
 289                                  FILTER_OTHER);
 290
 291         return ret;
 292 }
 293
 294 static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
 295 {
 296         struct trace_array *tr = data;
 297         struct trace_event_file *trace_file;
 298         struct syscall_trace_enter *entry;
 299         struct syscall_metadata *sys_data;
 300         struct ring_buffer_event *event;
 301         struct ring_buffer *buffer;
 302         unsigned long irq_flags;
 303         int pc;
 304         int syscall_nr;
 305         int size;
 306
 307         syscall_nr = trace_get_syscall_nr(current, regs);
 308         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
 309                 return;
 310
 311         /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE) */
 312         trace_file = rcu_dereference_sched(tr->enter_syscall_files[syscall_nr]);
 313         if (!trace_file)
 314                 return;
 315
 316         if (trace_trigger_soft_disabled(trace_file))
 317                 return;
 318
 319         sys_data = syscall_nr_to_meta(syscall_nr);
 320         if (!sys_data)
 321                 return;
 322
 323         size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
 324
 325         local_save_flags(irq_flags);
 326         pc = preempt_count();
 327
 328         buffer = tr->trace_buffer.buffer;
 329         event = trace_buffer_lock_reserve(buffer,
 330                         sys_data->enter_event->event.type, size, irq_flags, pc);
 331         if (!event)
 332                 return;
 333
 334         entry = ring_buffer_event_data(event);
 335         entry->nr = syscall_nr;
 336         syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
 337
 338         event_trigger_unlock_commit(trace_file, buffer, event, entry,
 339                                     irq_flags, pc);
 340 }
 341
 342 static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
 343 {
 344         struct trace_array *tr = data;
 345         struct trace_event_file *trace_file;
 346         struct syscall_trace_exit *entry;
 347         struct syscall_metadata *sys_data;
 348         struct ring_buffer_event *event;
 349         struct ring_buffer *buffer;
 350         unsigned long irq_flags;
 351         int pc;
 352         int syscall_nr;
 353
 354         syscall_nr = trace_get_syscall_nr(current, regs);
 355         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
 356                 return;
 357
 358         /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE()) */
 359         trace_file = rcu_dereference_sched(tr->exit_syscall_files[syscall_nr]);
 360         if (!trace_file)
 361                 return;
 362
 363         if (trace_trigger_soft_disabled(trace_file))
 364                 return;
 365
 366         sys_data = syscall_nr_to_meta(syscall_nr);
 367         if (!sys_data)
 368                 return;
 369
 370         local_save_flags(irq_flags);
 371         pc = preempt_count();
 372
 373         buffer = tr->trace_buffer.buffer;
 374         event = trace_buffer_lock_reserve(buffer,
 375                         sys_data->exit_event->event.type, sizeof(*entry),
 376                         irq_flags, pc);
 377         if (!event)
 378                 return;
 379
 380         entry = ring_buffer_event_data(event);
 381         entry->nr = syscall_nr;
 382         entry->ret = syscall_get_return_value(current, regs);
 383
 384         event_trigger_unlock_commit(trace_file, buffer, event, entry,
 385                                     irq_flags, pc);
 386 }
 387
 388 static int reg_event_syscall_enter(struct trace_event_file *file,
 389                                    struct trace_event_call *call)
 390 {
 391         struct trace_array *tr = file->tr;
 392         int ret = 0;
 393         int num;
 394
 395         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 396         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 397                 return -ENOSYS;
 398         mutex_lock(&syscall_trace_lock);
 399         if (!tr->sys_refcount_enter)
 400                 ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
 401         if (!ret) {
 402                 rcu_assign_pointer(tr->enter_syscall_files[num], file);
 403                 tr->sys_refcount_enter++;
 404         }
 405         mutex_unlock(&syscall_trace_lock);
 406         return ret;
 407 }
 408
 409 static void unreg_event_syscall_enter(struct trace_event_file *file,
 410                                       struct trace_event_call *call)
 411 {
 412         struct trace_array *tr = file->tr;
 413         int num;
 414
 415         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 416         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 417                 return;
 418         mutex_lock(&syscall_trace_lock);
 419         tr->sys_refcount_enter--;
 420         RCU_INIT_POINTER(tr->enter_syscall_files[num], NULL);
 421         if (!tr->sys_refcount_enter)
 422                 unregister_trace_sys_enter(ftrace_syscall_enter, tr);
 423         mutex_unlock(&syscall_trace_lock);
 424 }
 425
 426 static int reg_event_syscall_exit(struct trace_event_file *file,
 427                                   struct trace_event_call *call)
 428 {
 429         struct trace_array *tr = file->tr;
 430         int ret = 0;
 431         int num;
 432
 433         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 434         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 435                 return -ENOSYS;
 436         mutex_lock(&syscall_trace_lock);
 437         if (!tr->sys_refcount_exit)
 438                 ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
 439         if (!ret) {
 440                 rcu_assign_pointer(tr->exit_syscall_files[num], file);
 441                 tr->sys_refcount_exit++;
 442         }
 443         mutex_unlock(&syscall_trace_lock);
 444         return ret;
 445 }
 446
 447 static void unreg_event_syscall_exit(struct trace_event_file *file,
 448                                      struct trace_event_call *call)
 449 {
 450         struct trace_array *tr = file->tr;
 451         int num;
 452
 453         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 454         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 455                 return;
 456         mutex_lock(&syscall_trace_lock);
 457         tr->sys_refcount_exit--;
 458         RCU_INIT_POINTER(tr->exit_syscall_files[num], NULL);
 459         if (!tr->sys_refcount_exit)
 460                 unregister_trace_sys_exit(ftrace_syscall_exit, tr);
 461         mutex_unlock(&syscall_trace_lock);
 462 }
 463
 464 static int __init init_syscall_trace(struct trace_event_call *call)
 465 {
 466         int id;
 467         int num;
 468
 469         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 470         if (num < 0 || num >= NR_syscalls) {
 471                 pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
 472                                 ((struct syscall_metadata *)call->data)->name);
 473                 return -ENOSYS;
 474         }
 475
 476         if (set_syscall_print_fmt(call) < 0)
 477                 return -ENOMEM;
 478
 479         id = trace_event_raw_init(call);
 480
 481         if (id < 0) {
 482                 free_syscall_print_fmt(call);
 483                 return id;
 484         }
 485
 486         return id;
 487 }
 488
 489 struct trace_event_functions enter_syscall_print_funcs = {
 490         .trace          = print_syscall_enter,
 491 };
 492
 493 struct trace_event_functions exit_syscall_print_funcs = {
 494         .trace          = print_syscall_exit,
 495 };
 496
 497 struct trace_event_class __refdata event_class_syscall_enter = {
 498         .system         = "syscalls",
 499         .reg            = syscall_enter_register,
 500         .define_fields  = syscall_enter_define_fields,
 501         .get_fields     = syscall_get_enter_fields,
 502         .raw_init       = init_syscall_trace,
 503 };
 504
 505 struct trace_event_class __refdata event_class_syscall_exit = {
 506         .system         = "syscalls",
 507         .reg            = syscall_exit_register,
 508         .define_fields  = syscall_exit_define_fields,
 509         .fields         = LIST_HEAD_INIT(event_class_syscall_exit.fields),
 510         .raw_init       = init_syscall_trace,
 511 };
 512
 513 unsigned long __init __weak arch_syscall_addr(int nr)
 514 {
 515         return (unsigned long)sys_call_table[nr];
 516 }
 517
 518 void __init init_ftrace_syscalls(void)
 519 {
 520         struct syscall_metadata *meta;
 521         unsigned long addr;
 522         int i;
 523
 524         syscalls_metadata = kcalloc(NR_syscalls, sizeof(*syscalls_metadata),
 525                                     GFP_KERNEL);
 526         if (!syscalls_metadata) {
 527                 WARN_ON(1);
 528                 return;
 529         }
 530
 531         for (i = 0; i < NR_syscalls; i++) {
 532                 addr = arch_syscall_addr(i);
 533                 meta = find_syscall_meta(addr);
 534                 if (!meta)
 535                         continue;
 536
 537                 meta->syscall_nr = i;
 538                 syscalls_metadata[i] = meta;
 539         }
 540 }
 541
 542 #ifdef CONFIG_PERF_EVENTS
 543
 544 static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
 545 static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
 546 static int sys_perf_refcount_enter;
 547 static int sys_perf_refcount_exit;
 548
 549 static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
 550 {
 551         struct syscall_metadata *sys_data;
 552         struct syscall_trace_enter *rec;
 553         struct hlist_head *head;
 554         int syscall_nr;
 555         int rctx;
 556         int size;
 557
 558         syscall_nr = trace_get_syscall_nr(current, regs);
 559         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
 560                 return;
 561         if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
 562                 return;
 563
 564         sys_data = syscall_nr_to_meta(syscall_nr);
 565         if (!sys_data)
 566                 return;
 567
 568         head = this_cpu_ptr(sys_data->enter_event->perf_events);
 569         if (hlist_empty(head))
 570                 return;
 571
 572         /* get the size after alignment with the u32 buffer size field */
 573         size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
 574         size = ALIGN(size + sizeof(u32), sizeof(u64));
 575         size -= sizeof(u32);
 576
 577         rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size,
 578                                 sys_data->enter_event->event.type, NULL, &rctx);
 579         if (!rec)
 580                 return;
 581
 582         rec->nr = syscall_nr;
 583         syscall_get_arguments(current, regs, 0, sys_data->nb_args,
 584                                (unsigned long *)&rec->args);
 585         perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 586 }
 587
 588 static int perf_sysenter_enable(struct trace_event_call *call)
 589 {
 590         int ret = 0;
 591         int num;
 592
 593         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 594
 595         mutex_lock(&syscall_trace_lock);
 596         if (!sys_perf_refcount_enter)
 597                 ret = register_trace_sys_enter(perf_syscall_enter, NULL);
 598         if (ret) {
 599                 pr_info("event trace: Could not activate"
 600                                 "syscall entry trace point");
 601         } else {
 602                 set_bit(num, enabled_perf_enter_syscalls);
 603                 sys_perf_refcount_enter++;
 604         }
 605         mutex_unlock(&syscall_trace_lock);
 606         return ret;
 607 }
 608
 609 static void perf_sysenter_disable(struct trace_event_call *call)
 610 {
 611         int num;
 612
 613         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 614
 615         mutex_lock(&syscall_trace_lock);
 616         sys_perf_refcount_enter--;
 617         clear_bit(num, enabled_perf_enter_syscalls);
 618         if (!sys_perf_refcount_enter)
 619                 unregister_trace_sys_enter(perf_syscall_enter, NULL);
 620         mutex_unlock(&syscall_trace_lock);
 621 }
 622
 623 static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 624 {
 625         struct syscall_metadata *sys_data;
 626         struct syscall_trace_exit *rec;
 627         struct hlist_head *head;
 628         int syscall_nr;
 629         int rctx;
 630         int size;
 631
 632         syscall_nr = trace_get_syscall_nr(current, regs);
 633         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
 634                 return;
 635         if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
 636                 return;
 637
 638         sys_data = syscall_nr_to_meta(syscall_nr);
 639         if (!sys_data)
 640                 return;
 641
 642         head = this_cpu_ptr(sys_data->exit_event->perf_events);
 643         if (hlist_empty(head))
 644                 return;
 645
 646         /* We can probably do that at build time */
 647         size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
 648         size -= sizeof(u32);
 649
 650         rec = (struct syscall_trace_exit *)perf_trace_buf_prepare(size,
 651                                 sys_data->exit_event->event.type, NULL, &rctx);
 652         if (!rec)
 653                 return;
 654
 655         rec->nr = syscall_nr;
 656         rec->ret = syscall_get_return_value(current, regs);
 657         perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 658 }
 659
 660 static int perf_sysexit_enable(struct trace_event_call *call)
 661 {
 662         int ret = 0;
 663         int num;
 664
 665         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 666
 667         mutex_lock(&syscall_trace_lock);
 668         if (!sys_perf_refcount_exit)
 669                 ret = register_trace_sys_exit(perf_syscall_exit, NULL);
 670         if (ret) {
 671                 pr_info("event trace: Could not activate"
 672                                 "syscall exit trace point");
 673         } else {
 674                 set_bit(num, enabled_perf_exit_syscalls);
 675                 sys_perf_refcount_exit++;
 676         }
 677         mutex_unlock(&syscall_trace_lock);
 678         return ret;
 679 }
 680
 681 static void perf_sysexit_disable(struct trace_event_call *call)
 682 {
 683         int num;
 684
 685         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 686
 687         mutex_lock(&syscall_trace_lock);
 688         sys_perf_refcount_exit--;
 689         clear_bit(num, enabled_perf_exit_syscalls);
 690         if (!sys_perf_refcount_exit)
 691                 unregister_trace_sys_exit(perf_syscall_exit, NULL);
 692         mutex_unlock(&syscall_trace_lock);
 693 }
 694
 695 #endif /* CONFIG_PERF_EVENTS */
 696
 697 static int syscall_enter_register(struct trace_event_call *event,
 698                                  enum trace_reg type, void *data)
 699 {
 700         struct trace_event_file *file = data;
 701
 702         switch (type) {
 703         case TRACE_REG_REGISTER:
 704                 return reg_event_syscall_enter(file, event);
 705         case TRACE_REG_UNREGISTER:
 706                 unreg_event_syscall_enter(file, event);
 707                 return 0;
 708
 709 #ifdef CONFIG_PERF_EVENTS
 710         case TRACE_REG_PERF_REGISTER:
 711                 return perf_sysenter_enable(event);
 712         case TRACE_REG_PERF_UNREGISTER:
 713                 perf_sysenter_disable(event);
 714                 return 0;
 715         case TRACE_REG_PERF_OPEN:
 716         case TRACE_REG_PERF_CLOSE:
 717         case TRACE_REG_PERF_ADD:
 718         case TRACE_REG_PERF_DEL:
 719                 return 0;
 720 #endif
 721         }
 722         return 0;
 723 }
 724
 725 static int syscall_exit_register(struct trace_event_call *event,
 726                                  enum trace_reg type, void *data)
 727 {
 728         struct trace_event_file *file = data;
 729
 730         switch (type) {
 731         case TRACE_REG_REGISTER:
 732                 return reg_event_syscall_exit(file, event);
 733         case TRACE_REG_UNREGISTER:
 734                 unreg_event_syscall_exit(file, event);
 735                 return 0;
 736
 737 #ifdef CONFIG_PERF_EVENTS
 738         case TRACE_REG_PERF_REGISTER:
 739                 return perf_sysexit_enable(event);
 740         case TRACE_REG_PERF_UNREGISTER:
 741                 perf_sysexit_disable(event);
 742                 return 0;
 743         case TRACE_REG_PERF_OPEN:
 744         case TRACE_REG_PERF_CLOSE:
 745         case TRACE_REG_PERF_ADD:
 746         case TRACE_REG_PERF_DEL:
 747                 return 0;
 748 #endif
 749         }
 750         return 0;
 751 }