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