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 const char *get_syscall_name(int syscall)
 110 {
 111         struct syscall_metadata *entry;
 112
 113         entry = syscall_nr_to_meta(syscall);
 114         if (!entry)
 115                 return NULL;
 116
 117         return entry->name;
 118 }
 119
 120 static enum print_line_t
 121 print_syscall_enter(struct trace_iterator *iter, int flags,
 122                     struct trace_event *event)
 123 {
 124         struct trace_array *tr = iter->tr;
 125         struct trace_seq *s = &iter->seq;
 126         struct trace_entry *ent = iter->ent;
 127         struct syscall_trace_enter *trace;
 128         struct syscall_metadata *entry;
 129         int i, syscall;
 130
 131         trace = (typeof(trace))ent;
 132         syscall = trace->nr;
 133         entry = syscall_nr_to_meta(syscall);
 134
 135         if (!entry)
 136                 goto end;
 137
 138         if (entry->enter_event->event.type != ent->type) {
 139                 WARN_ON_ONCE(1);
 140                 goto end;
 141         }
 142
 143         trace_seq_printf(s, "%s(", entry->name);
 144
 145         for (i = 0; i < entry->nb_args; i++) {
 146
 147                 if (trace_seq_has_overflowed(s))
 148                         goto end;
 149
 150                 /* parameter types */
 151                 if (tr->trace_flags & TRACE_ITER_VERBOSE)
 152                         trace_seq_printf(s, "%s ", entry->types[i]);
 153
 154                 /* parameter values */
 155                 trace_seq_printf(s, "%s: %lx%s", entry->args[i],
 156                                  trace->args[i],
 157                                  i == entry->nb_args - 1 ? "" : ", ");
 158         }
 159
 160         trace_seq_putc(s, ')');
 161 end:
 162         trace_seq_putc(s, '\n');
 163
 164         return trace_handle_return(s);
 165 }
 166
 167 static enum print_line_t
 168 print_syscall_exit(struct trace_iterator *iter, int flags,
 169                    struct trace_event *event)
 170 {
 171         struct trace_seq *s = &iter->seq;
 172         struct trace_entry *ent = iter->ent;
 173         struct syscall_trace_exit *trace;
 174         int syscall;
 175         struct syscall_metadata *entry;
 176
 177         trace = (typeof(trace))ent;
 178         syscall = trace->nr;
 179         entry = syscall_nr_to_meta(syscall);
 180
 181         if (!entry) {
 182                 trace_seq_putc(s, '\n');
 183                 goto out;
 184         }
 185
 186         if (entry->exit_event->event.type != ent->type) {
 187                 WARN_ON_ONCE(1);
 188                 return TRACE_TYPE_UNHANDLED;
 189         }
 190
 191         trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
 192                                 trace->ret);
 193
 194  out:
 195         return trace_handle_return(s);
 196 }
 197
 198 extern char *__bad_type_size(void);
 199
 200 #define SYSCALL_FIELD(type, field, name)                                \
 201         sizeof(type) != sizeof(trace.field) ?                           \
 202                 __bad_type_size() :                                     \
 203                 #type, #name, offsetof(typeof(trace), field),           \
 204                 sizeof(trace.field), is_signed_type(type)
 205
 206 static int __init
 207 __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
 208 {
 209         int i;
 210         int pos = 0;
 211
 212         /* When len=0, we just calculate the needed length */
 213 #define LEN_OR_ZERO (len ? len - pos : 0)
 214
 215         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 216         for (i = 0; i < entry->nb_args; i++) {
 217                 pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
 218                                 entry->args[i], sizeof(unsigned long),
 219                                 i == entry->nb_args - 1 ? "" : ", ");
 220         }
 221         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 222
 223         for (i = 0; i < entry->nb_args; i++) {
 224                 pos += snprintf(buf + pos, LEN_OR_ZERO,
 225                                 ", ((unsigned long)(REC->%s))", entry->args[i]);
 226         }
 227
 228 #undef LEN_OR_ZERO
 229
 230         /* return the length of print_fmt */
 231         return pos;
 232 }
 233
 234 static int __init set_syscall_print_fmt(struct trace_event_call *call)
 235 {
 236         char *print_fmt;
 237         int len;
 238         struct syscall_metadata *entry = call->data;
 239
 240         if (entry->enter_event != call) {
 241                 call->print_fmt = "\"0x%lx\", REC->ret";
 242                 return 0;
 243         }
 244
 245         /* First: called with 0 length to calculate the needed length */
 246         len = __set_enter_print_fmt(entry, NULL, 0);
 247
 248         print_fmt = kmalloc(len + 1, GFP_KERNEL);
 249         if (!print_fmt)
 250                 return -ENOMEM;
 251
 252         /* Second: actually write the @print_fmt */
 253         __set_enter_print_fmt(entry, print_fmt, len + 1);
 254         call->print_fmt = print_fmt;
 255
 256         return 0;
 257 }
 258
 259 static void __init free_syscall_print_fmt(struct trace_event_call *call)
 260 {
 261         struct syscall_metadata *entry = call->data;
 262
 263         if (entry->enter_event == call)
 264                 kfree(call->print_fmt);
 265 }
 266
 267 static int __init syscall_enter_define_fields(struct trace_event_call *call)
 268 {
 269         struct syscall_trace_enter trace;
 270         struct syscall_metadata *meta = call->data;
 271         int ret;
 272         int i;
 273         int offset = offsetof(typeof(trace), args);
 274
 275         ret = trace_define_field(call, SYSCALL_FIELD(int, nr, __syscall_nr),
 276                                  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 __init syscall_exit_define_fields(struct trace_event_call *call)
 292 {
 293         struct syscall_trace_exit trace;
 294         int ret;
 295
 296         ret = trace_define_field(call, SYSCALL_FIELD(int, nr, __syscall_nr),
 297                                  FILTER_OTHER);
 298         if (ret)
 299                 return ret;
 300
 301         ret = trace_define_field(call, SYSCALL_FIELD(long, ret, ret),
 302                                  FILTER_OTHER);
 303
 304         return ret;
 305 }
 306
 307 static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
 308 {
 309         struct trace_array *tr = data;
 310         struct trace_event_file *trace_file;
 311         struct syscall_trace_enter *entry;
 312         struct syscall_metadata *sys_data;
 313         struct ring_buffer_event *event;
 314         struct ring_buffer *buffer;
 315         unsigned long irq_flags;
 316         int pc;
 317         int syscall_nr;
 318         int size;
 319
 320         syscall_nr = trace_get_syscall_nr(current, regs);
 321         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
 322                 return;
 323
 324         /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE) */
 325         trace_file = rcu_dereference_sched(tr->enter_syscall_files[syscall_nr]);
 326         if (!trace_file)
 327                 return;
 328
 329         if (trace_trigger_soft_disabled(trace_file))
 330                 return;
 331
 332         sys_data = syscall_nr_to_meta(syscall_nr);
 333         if (!sys_data)
 334                 return;
 335
 336         size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
 337
 338         local_save_flags(irq_flags);
 339         pc = preempt_count();
 340
 341         buffer = tr->trace_buffer.buffer;
 342         event = trace_buffer_lock_reserve(buffer,
 343                         sys_data->enter_event->event.type, size, irq_flags, pc);
 344         if (!event)
 345                 return;
 346
 347         entry = ring_buffer_event_data(event);
 348         entry->nr = syscall_nr;
 349         syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
 350
 351         event_trigger_unlock_commit(trace_file, buffer, event, entry,
 352                                     irq_flags, pc);
 353 }
 354
 355 static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
 356 {
 357         struct trace_array *tr = data;
 358         struct trace_event_file *trace_file;
 359         struct syscall_trace_exit *entry;
 360         struct syscall_metadata *sys_data;
 361         struct ring_buffer_event *event;
 362         struct ring_buffer *buffer;
 363         unsigned long irq_flags;
 364         int pc;
 365         int syscall_nr;
 366
 367         syscall_nr = trace_get_syscall_nr(current, regs);
 368         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
 369                 return;
 370
 371         /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE()) */
 372         trace_file = rcu_dereference_sched(tr->exit_syscall_files[syscall_nr]);
 373         if (!trace_file)
 374                 return;
 375
 376         if (trace_trigger_soft_disabled(trace_file))
 377                 return;
 378
 379         sys_data = syscall_nr_to_meta(syscall_nr);
 380         if (!sys_data)
 381                 return;
 382
 383         local_save_flags(irq_flags);
 384         pc = preempt_count();
 385
 386         buffer = tr->trace_buffer.buffer;
 387         event = trace_buffer_lock_reserve(buffer,
 388                         sys_data->exit_event->event.type, sizeof(*entry),
 389                         irq_flags, pc);
 390         if (!event)
 391                 return;
 392
 393         entry = ring_buffer_event_data(event);
 394         entry->nr = syscall_nr;
 395         entry->ret = syscall_get_return_value(current, regs);
 396
 397         event_trigger_unlock_commit(trace_file, buffer, event, entry,
 398                                     irq_flags, pc);
 399 }
 400
 401 static int reg_event_syscall_enter(struct trace_event_file *file,
 402                                    struct trace_event_call *call)
 403 {
 404         struct trace_array *tr = file->tr;
 405         int ret = 0;
 406         int num;
 407
 408         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 409         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 410                 return -ENOSYS;
 411         mutex_lock(&syscall_trace_lock);
 412         if (!tr->sys_refcount_enter)
 413                 ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
 414         if (!ret) {
 415                 rcu_assign_pointer(tr->enter_syscall_files[num], file);
 416                 tr->sys_refcount_enter++;
 417         }
 418         mutex_unlock(&syscall_trace_lock);
 419         return ret;
 420 }
 421
 422 static void unreg_event_syscall_enter(struct trace_event_file *file,
 423                                       struct trace_event_call *call)
 424 {
 425         struct trace_array *tr = file->tr;
 426         int num;
 427
 428         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 429         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 430                 return;
 431         mutex_lock(&syscall_trace_lock);
 432         tr->sys_refcount_enter--;
 433         RCU_INIT_POINTER(tr->enter_syscall_files[num], NULL);
 434         if (!tr->sys_refcount_enter)
 435                 unregister_trace_sys_enter(ftrace_syscall_enter, tr);
 436         mutex_unlock(&syscall_trace_lock);
 437 }
 438
 439 static int reg_event_syscall_exit(struct trace_event_file *file,
 440                                   struct trace_event_call *call)
 441 {
 442         struct trace_array *tr = file->tr;
 443         int ret = 0;
 444         int num;
 445
 446         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 447         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 448                 return -ENOSYS;
 449         mutex_lock(&syscall_trace_lock);
 450         if (!tr->sys_refcount_exit)
 451                 ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
 452         if (!ret) {
 453                 rcu_assign_pointer(tr->exit_syscall_files[num], file);
 454                 tr->sys_refcount_exit++;
 455         }
 456         mutex_unlock(&syscall_trace_lock);
 457         return ret;
 458 }
 459
 460 static void unreg_event_syscall_exit(struct trace_event_file *file,
 461                                      struct trace_event_call *call)
 462 {
 463         struct trace_array *tr = file->tr;
 464         int num;
 465
 466         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 467         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 468                 return;
 469         mutex_lock(&syscall_trace_lock);
 470         tr->sys_refcount_exit--;
 471         RCU_INIT_POINTER(tr->exit_syscall_files[num], NULL);
 472         if (!tr->sys_refcount_exit)
 473                 unregister_trace_sys_exit(ftrace_syscall_exit, tr);
 474         mutex_unlock(&syscall_trace_lock);
 475 }
 476
 477 static int __init init_syscall_trace(struct trace_event_call *call)
 478 {
 479         int id;
 480         int num;
 481
 482         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 483         if (num < 0 || num >= NR_syscalls) {
 484                 pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
 485                                 ((struct syscall_metadata *)call->data)->name);
 486                 return -ENOSYS;
 487         }
 488
 489         if (set_syscall_print_fmt(call) < 0)
 490                 return -ENOMEM;
 491
 492         id = trace_event_raw_init(call);
 493
 494         if (id < 0) {
 495                 free_syscall_print_fmt(call);
 496                 return id;
 497         }
 498
 499         return id;
 500 }
 501
 502 struct trace_event_functions enter_syscall_print_funcs = {
 503         .trace          = print_syscall_enter,
 504 };
 505
 506 struct trace_event_functions exit_syscall_print_funcs = {
 507         .trace          = print_syscall_exit,
 508 };
 509
 510 struct trace_event_class __refdata event_class_syscall_enter = {
 511         .system         = "syscalls",
 512         .reg            = syscall_enter_register,
 513         .define_fields  = syscall_enter_define_fields,
 514         .get_fields     = syscall_get_enter_fields,
 515         .raw_init       = init_syscall_trace,
 516 };
 517
 518 struct trace_event_class __refdata event_class_syscall_exit = {
 519         .system         = "syscalls",
 520         .reg            = syscall_exit_register,
 521         .define_fields  = syscall_exit_define_fields,
 522         .fields         = LIST_HEAD_INIT(event_class_syscall_exit.fields),
 523         .raw_init       = init_syscall_trace,
 524 };
 525
 526 unsigned long __init __weak arch_syscall_addr(int nr)
 527 {
 528         return (unsigned long)sys_call_table[nr];
 529 }
 530
 531 void __init init_ftrace_syscalls(void)
 532 {
 533         struct syscall_metadata *meta;
 534         unsigned long addr;
 535         int i;
 536
 537         syscalls_metadata = kcalloc(NR_syscalls, sizeof(*syscalls_metadata),
 538                                     GFP_KERNEL);
 539         if (!syscalls_metadata) {
 540                 WARN_ON(1);
 541                 return;
 542         }
 543
 544         for (i = 0; i < NR_syscalls; i++) {
 545                 addr = arch_syscall_addr(i);
 546                 meta = find_syscall_meta(addr);
 547                 if (!meta)
 548                         continue;
 549
 550                 meta->syscall_nr = i;
 551                 syscalls_metadata[i] = meta;
 552         }
 553 }
 554
 555 #ifdef CONFIG_PERF_EVENTS
 556
 557 static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
 558 static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
 559 static int sys_perf_refcount_enter;
 560 static int sys_perf_refcount_exit;
 561
 562 static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
 563 {
 564         struct syscall_metadata *sys_data;
 565         struct syscall_trace_enter *rec;
 566         struct hlist_head *head;
 567         int syscall_nr;
 568         int rctx;
 569         int size;
 570
 571         syscall_nr = trace_get_syscall_nr(current, regs);
 572         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
 573                 return;
 574         if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
 575                 return;
 576
 577         sys_data = syscall_nr_to_meta(syscall_nr);
 578         if (!sys_data)
 579                 return;
 580
 581         head = this_cpu_ptr(sys_data->enter_event->perf_events);
 582         if (hlist_empty(head))
 583                 return;
 584
 585         /* get the size after alignment with the u32 buffer size field */
 586         size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
 587         size = ALIGN(size + sizeof(u32), sizeof(u64));
 588         size -= sizeof(u32);
 589
 590         rec = perf_trace_buf_alloc(size, NULL, &rctx);
 591         if (!rec)
 592                 return;
 593
 594         rec->nr = syscall_nr;
 595         syscall_get_arguments(current, regs, 0, sys_data->nb_args,
 596                                (unsigned long *)&rec->args);
 597         perf_trace_buf_submit(rec, size, rctx,
 598                               sys_data->enter_event->event.type, 1, regs,
 599                               head, NULL);
 600 }
 601
 602 static int perf_sysenter_enable(struct trace_event_call *call)
 603 {
 604         int ret = 0;
 605         int num;
 606
 607         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 608
 609         mutex_lock(&syscall_trace_lock);
 610         if (!sys_perf_refcount_enter)
 611                 ret = register_trace_sys_enter(perf_syscall_enter, NULL);
 612         if (ret) {
 613                 pr_info("event trace: Could not activate syscall entry trace point");
 614         } else {
 615                 set_bit(num, enabled_perf_enter_syscalls);
 616                 sys_perf_refcount_enter++;
 617         }
 618         mutex_unlock(&syscall_trace_lock);
 619         return ret;
 620 }
 621
 622 static void perf_sysenter_disable(struct trace_event_call *call)
 623 {
 624         int num;
 625
 626         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 627
 628         mutex_lock(&syscall_trace_lock);
 629         sys_perf_refcount_enter--;
 630         clear_bit(num, enabled_perf_enter_syscalls);
 631         if (!sys_perf_refcount_enter)
 632                 unregister_trace_sys_enter(perf_syscall_enter, NULL);
 633         mutex_unlock(&syscall_trace_lock);
 634 }
 635
 636 static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 637 {
 638         struct syscall_metadata *sys_data;
 639         struct syscall_trace_exit *rec;
 640         struct hlist_head *head;
 641         int syscall_nr;
 642         int rctx;
 643         int size;
 644
 645         syscall_nr = trace_get_syscall_nr(current, regs);
 646         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
 647                 return;
 648         if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
 649                 return;
 650
 651         sys_data = syscall_nr_to_meta(syscall_nr);
 652         if (!sys_data)
 653                 return;
 654
 655         head = this_cpu_ptr(sys_data->exit_event->perf_events);
 656         if (hlist_empty(head))
 657                 return;
 658
 659         /* We can probably do that at build time */
 660         size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
 661         size -= sizeof(u32);
 662
 663         rec = perf_trace_buf_alloc(size, NULL, &rctx);
 664         if (!rec)
 665                 return;
 666
 667         rec->nr = syscall_nr;
 668         rec->ret = syscall_get_return_value(current, regs);
 669         perf_trace_buf_submit(rec, size, rctx, sys_data->exit_event->event.type,
 670                               1, regs, head, NULL);
 671 }
 672
 673 static int perf_sysexit_enable(struct trace_event_call *call)
 674 {
 675         int ret = 0;
 676         int num;
 677
 678         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 679
 680         mutex_lock(&syscall_trace_lock);
 681         if (!sys_perf_refcount_exit)
 682                 ret = register_trace_sys_exit(perf_syscall_exit, NULL);
 683         if (ret) {
 684                 pr_info("event trace: Could not activate syscall exit trace point");
 685         } else {
 686                 set_bit(num, enabled_perf_exit_syscalls);
 687                 sys_perf_refcount_exit++;
 688         }
 689         mutex_unlock(&syscall_trace_lock);
 690         return ret;
 691 }
 692
 693 static void perf_sysexit_disable(struct trace_event_call *call)
 694 {
 695         int num;
 696
 697         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 698
 699         mutex_lock(&syscall_trace_lock);
 700         sys_perf_refcount_exit--;
 701         clear_bit(num, enabled_perf_exit_syscalls);
 702         if (!sys_perf_refcount_exit)
 703                 unregister_trace_sys_exit(perf_syscall_exit, NULL);
 704         mutex_unlock(&syscall_trace_lock);
 705 }
 706
 707 #endif /* CONFIG_PERF_EVENTS */
 708
 709 static int syscall_enter_register(struct trace_event_call *event,
 710                                  enum trace_reg type, void *data)
 711 {
 712         struct trace_event_file *file = data;
 713
 714         switch (type) {
 715         case TRACE_REG_REGISTER:
 716                 return reg_event_syscall_enter(file, event);
 717         case TRACE_REG_UNREGISTER:
 718                 unreg_event_syscall_enter(file, event);
 719                 return 0;
 720
 721 #ifdef CONFIG_PERF_EVENTS
 722         case TRACE_REG_PERF_REGISTER:
 723                 return perf_sysenter_enable(event);
 724         case TRACE_REG_PERF_UNREGISTER:
 725                 perf_sysenter_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 }
 736
 737 static int syscall_exit_register(struct trace_event_call *event,
 738                                  enum trace_reg type, void *data)
 739 {
 740         struct trace_event_file *file = data;
 741
 742         switch (type) {
 743         case TRACE_REG_REGISTER:
 744                 return reg_event_syscall_exit(file, event);
 745         case TRACE_REG_UNREGISTER:
 746                 unreg_event_syscall_exit(file, event);
 747                 return 0;
 748
 749 #ifdef CONFIG_PERF_EVENTS
 750         case TRACE_REG_PERF_REGISTER:
 751                 return perf_sysexit_enable(event);
 752         case TRACE_REG_PERF_UNREGISTER:
 753                 perf_sysexit_disable(event);
 754                 return 0;
 755         case TRACE_REG_PERF_OPEN:
 756         case TRACE_REG_PERF_CLOSE:
 757         case TRACE_REG_PERF_ADD:
 758         case TRACE_REG_PERF_DEL:
 759                 return 0;
 760 #endif
 761         }
 762         return 0;
 763 }