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 ftrace_event_call *event,
  17                                  enum trace_reg type, void *data);
  18 static int syscall_exit_register(struct ftrace_event_call *event,
  19                                  enum trace_reg type, void *data);
  20
  21 static struct list_head *
  22 syscall_get_enter_fields(struct ftrace_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_seq *s = &iter->seq;
 114         struct trace_entry *ent = iter->ent;
 115         struct syscall_trace_enter *trace;
 116         struct syscall_metadata *entry;
 117         int i, syscall;
 118
 119         trace = (typeof(trace))ent;
 120         syscall = trace->nr;
 121         entry = syscall_nr_to_meta(syscall);
 122
 123         if (!entry)
 124                 goto end;
 125
 126         if (entry->enter_event->event.type != ent->type) {
 127                 WARN_ON_ONCE(1);
 128                 goto end;
 129         }
 130
 131         trace_seq_printf(s, "%s(", entry->name);
 132
 133         for (i = 0; i < entry->nb_args; i++) {
 134
 135                 if (trace_seq_has_overflowed(s))
 136                         goto end;
 137
 138                 /* parameter types */
 139                 if (trace_flags & TRACE_ITER_VERBOSE)
 140                         trace_seq_printf(s, "%s ", entry->types[i]);
 141
 142                 /* parameter values */
 143                 trace_seq_printf(s, "%s: %lx%s", entry->args[i],
 144                                  trace->args[i],
 145                                  i == entry->nb_args - 1 ? "" : ", ");
 146         }
 147
 148         trace_seq_putc(s, ')');
 149 end:
 150         trace_seq_putc(s, '\n');
 151
 152         return trace_handle_return(s);
 153 }
 154
 155 static enum print_line_t
 156 print_syscall_exit(struct trace_iterator *iter, int flags,
 157                    struct trace_event *event)
 158 {
 159         struct trace_seq *s = &iter->seq;
 160         struct trace_entry *ent = iter->ent;
 161         struct syscall_trace_exit *trace;
 162         int syscall;
 163         struct syscall_metadata *entry;
 164
 165         trace = (typeof(trace))ent;
 166         syscall = trace->nr;
 167         entry = syscall_nr_to_meta(syscall);
 168
 169         if (!entry) {
 170                 trace_seq_putc(s, '\n');
 171                 goto out;
 172         }
 173
 174         if (entry->exit_event->event.type != ent->type) {
 175                 WARN_ON_ONCE(1);
 176                 return TRACE_TYPE_UNHANDLED;
 177         }
 178
 179         trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
 180                                 trace->ret);
 181
 182  out:
 183         return trace_handle_return(s);
 184 }
 185
 186 extern char *__bad_type_size(void);
 187
 188 #define SYSCALL_FIELD(type, name)                                       \
 189         sizeof(type) != sizeof(trace.name) ?                            \
 190                 __bad_type_size() :                                     \
 191                 #type, #name, offsetof(typeof(trace), name),            \
 192                 sizeof(trace.name), is_signed_type(type)
 193
 194 static int __init
 195 __set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
 196 {
 197         int i;
 198         int pos = 0;
 199
 200         /* When len=0, we just calculate the needed length */
 201 #define LEN_OR_ZERO (len ? len - pos : 0)
 202
 203         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 204         for (i = 0; i < entry->nb_args; i++) {
 205                 pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
 206                                 entry->args[i], sizeof(unsigned long),
 207                                 i == entry->nb_args - 1 ? "" : ", ");
 208         }
 209         pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
 210
 211         for (i = 0; i < entry->nb_args; i++) {
 212                 pos += snprintf(buf + pos, LEN_OR_ZERO,
 213                                 ", ((unsigned long)(REC->%s))", entry->args[i]);
 214         }
 215
 216 #undef LEN_OR_ZERO
 217
 218         /* return the length of print_fmt */
 219         return pos;
 220 }
 221
 222 static int __init set_syscall_print_fmt(struct ftrace_event_call *call)
 223 {
 224         char *print_fmt;
 225         int len;
 226         struct syscall_metadata *entry = call->data;
 227
 228         if (entry->enter_event != call) {
 229                 call->print_fmt = "\"0x%lx\", REC->ret";
 230                 return 0;
 231         }
 232
 233         /* First: called with 0 length to calculate the needed length */
 234         len = __set_enter_print_fmt(entry, NULL, 0);
 235
 236         print_fmt = kmalloc(len + 1, GFP_KERNEL);
 237         if (!print_fmt)
 238                 return -ENOMEM;
 239
 240         /* Second: actually write the @print_fmt */
 241         __set_enter_print_fmt(entry, print_fmt, len + 1);
 242         call->print_fmt = print_fmt;
 243
 244         return 0;
 245 }
 246
 247 static void __init free_syscall_print_fmt(struct ftrace_event_call *call)
 248 {
 249         struct syscall_metadata *entry = call->data;
 250
 251         if (entry->enter_event == call)
 252                 kfree(call->print_fmt);
 253 }
 254
 255 static int __init syscall_enter_define_fields(struct ftrace_event_call *call)
 256 {
 257         struct syscall_trace_enter trace;
 258         struct syscall_metadata *meta = call->data;
 259         int ret;
 260         int i;
 261         int offset = offsetof(typeof(trace), args);
 262
 263         ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
 264         if (ret)
 265                 return ret;
 266
 267         for (i = 0; i < meta->nb_args; i++) {
 268                 ret = trace_define_field(call, meta->types[i],
 269                                          meta->args[i], offset,
 270                                          sizeof(unsigned long), 0,
 271                                          FILTER_OTHER);
 272                 offset += sizeof(unsigned long);
 273         }
 274
 275         return ret;
 276 }
 277
 278 static int __init syscall_exit_define_fields(struct ftrace_event_call *call)
 279 {
 280         struct syscall_trace_exit trace;
 281         int ret;
 282
 283         ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
 284         if (ret)
 285                 return ret;
 286
 287         ret = trace_define_field(call, SYSCALL_FIELD(long, ret),
 288                                  FILTER_OTHER);
 289
 290         return ret;
 291 }
 292
 293 static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
 294 {
 295         struct trace_array *tr = data;
 296         struct ftrace_event_file *ftrace_file;
 297         struct syscall_trace_enter *entry;
 298         struct syscall_metadata *sys_data;
 299         struct ring_buffer_event *event;
 300         struct ring_buffer *buffer;
 301         unsigned long irq_flags;
 302         int pc;
 303         int syscall_nr;
 304         int size;
 305
 306         syscall_nr = trace_get_syscall_nr(current, regs);
 307         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
 308                 return;
 309
 310         /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE) */
 311         ftrace_file = rcu_dereference_sched(tr->enter_syscall_files[syscall_nr]);
 312         if (!ftrace_file)
 313                 return;
 314
 315         if (ftrace_trigger_soft_disabled(ftrace_file))
 316                 return;
 317
 318         sys_data = syscall_nr_to_meta(syscall_nr);
 319         if (!sys_data)
 320                 return;
 321
 322         size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
 323
 324         local_save_flags(irq_flags);
 325         pc = preempt_count();
 326
 327         buffer = tr->trace_buffer.buffer;
 328         event = trace_buffer_lock_reserve(buffer,
 329                         sys_data->enter_event->event.type, size, irq_flags, pc);
 330         if (!event)
 331                 return;
 332
 333         entry = ring_buffer_event_data(event);
 334         entry->nr = syscall_nr;
 335         syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
 336
 337         event_trigger_unlock_commit(ftrace_file, buffer, event, entry,
 338                                     irq_flags, pc);
 339 }
 340
 341 static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
 342 {
 343         struct trace_array *tr = data;
 344         struct ftrace_event_file *ftrace_file;
 345         struct syscall_trace_exit *entry;
 346         struct syscall_metadata *sys_data;
 347         struct ring_buffer_event *event;
 348         struct ring_buffer *buffer;
 349         unsigned long irq_flags;
 350         int pc;
 351         int syscall_nr;
 352
 353         syscall_nr = trace_get_syscall_nr(current, regs);
 354         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
 355                 return;
 356
 357         /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE()) */
 358         ftrace_file = rcu_dereference_sched(tr->exit_syscall_files[syscall_nr]);
 359         if (!ftrace_file)
 360                 return;
 361
 362         if (ftrace_trigger_soft_disabled(ftrace_file))
 363                 return;
 364
 365         sys_data = syscall_nr_to_meta(syscall_nr);
 366         if (!sys_data)
 367                 return;
 368
 369         local_save_flags(irq_flags);
 370         pc = preempt_count();
 371
 372         buffer = tr->trace_buffer.buffer;
 373         event = trace_buffer_lock_reserve(buffer,
 374                         sys_data->exit_event->event.type, sizeof(*entry),
 375                         irq_flags, pc);
 376         if (!event)
 377                 return;
 378
 379         entry = ring_buffer_event_data(event);
 380         entry->nr = syscall_nr;
 381         entry->ret = syscall_get_return_value(current, regs);
 382
 383         event_trigger_unlock_commit(ftrace_file, buffer, event, entry,
 384                                     irq_flags, pc);
 385 }
 386
 387 static int reg_event_syscall_enter(struct ftrace_event_file *file,
 388                                    struct ftrace_event_call *call)
 389 {
 390         struct trace_array *tr = file->tr;
 391         int ret = 0;
 392         int num;
 393
 394         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 395         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 396                 return -ENOSYS;
 397         mutex_lock(&syscall_trace_lock);
 398         if (!tr->sys_refcount_enter)
 399                 ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
 400         if (!ret) {
 401                 rcu_assign_pointer(tr->enter_syscall_files[num], file);
 402                 tr->sys_refcount_enter++;
 403         }
 404         mutex_unlock(&syscall_trace_lock);
 405         return ret;
 406 }
 407
 408 static void unreg_event_syscall_enter(struct ftrace_event_file *file,
 409                                       struct ftrace_event_call *call)
 410 {
 411         struct trace_array *tr = file->tr;
 412         int num;
 413
 414         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 415         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 416                 return;
 417         mutex_lock(&syscall_trace_lock);
 418         tr->sys_refcount_enter--;
 419         RCU_INIT_POINTER(tr->enter_syscall_files[num], NULL);
 420         if (!tr->sys_refcount_enter)
 421                 unregister_trace_sys_enter(ftrace_syscall_enter, tr);
 422         mutex_unlock(&syscall_trace_lock);
 423 }
 424
 425 static int reg_event_syscall_exit(struct ftrace_event_file *file,
 426                                   struct ftrace_event_call *call)
 427 {
 428         struct trace_array *tr = file->tr;
 429         int ret = 0;
 430         int num;
 431
 432         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 433         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 434                 return -ENOSYS;
 435         mutex_lock(&syscall_trace_lock);
 436         if (!tr->sys_refcount_exit)
 437                 ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
 438         if (!ret) {
 439                 rcu_assign_pointer(tr->exit_syscall_files[num], file);
 440                 tr->sys_refcount_exit++;
 441         }
 442         mutex_unlock(&syscall_trace_lock);
 443         return ret;
 444 }
 445
 446 static void unreg_event_syscall_exit(struct ftrace_event_file *file,
 447                                      struct ftrace_event_call *call)
 448 {
 449         struct trace_array *tr = file->tr;
 450         int num;
 451
 452         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 453         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 454                 return;
 455         mutex_lock(&syscall_trace_lock);
 456         tr->sys_refcount_exit--;
 457         RCU_INIT_POINTER(tr->exit_syscall_files[num], NULL);
 458         if (!tr->sys_refcount_exit)
 459                 unregister_trace_sys_exit(ftrace_syscall_exit, tr);
 460         mutex_unlock(&syscall_trace_lock);
 461 }
 462
 463 static int __init init_syscall_trace(struct ftrace_event_call *call)
 464 {
 465         int id;
 466         int num;
 467
 468         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 469         if (num < 0 || num >= NR_syscalls) {
 470                 pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
 471                                 ((struct syscall_metadata *)call->data)->name);
 472                 return -ENOSYS;
 473         }
 474
 475         if (set_syscall_print_fmt(call) < 0)
 476                 return -ENOMEM;
 477
 478         id = trace_event_raw_init(call);
 479
 480         if (id < 0) {
 481                 free_syscall_print_fmt(call);
 482                 return id;
 483         }
 484
 485         return id;
 486 }
 487
 488 struct trace_event_functions enter_syscall_print_funcs = {
 489         .trace          = print_syscall_enter,
 490 };
 491
 492 struct trace_event_functions exit_syscall_print_funcs = {
 493         .trace          = print_syscall_exit,
 494 };
 495
 496 struct ftrace_event_class __refdata event_class_syscall_enter = {
 497         .system         = "syscalls",
 498         .reg            = syscall_enter_register,
 499         .define_fields  = syscall_enter_define_fields,
 500         .get_fields     = syscall_get_enter_fields,
 501         .raw_init       = init_syscall_trace,
 502 };
 503
 504 struct ftrace_event_class __refdata event_class_syscall_exit = {
 505         .system         = "syscalls",
 506         .reg            = syscall_exit_register,
 507         .define_fields  = syscall_exit_define_fields,
 508         .fields         = LIST_HEAD_INIT(event_class_syscall_exit.fields),
 509         .raw_init       = init_syscall_trace,
 510 };
 511
 512 unsigned long __init __weak arch_syscall_addr(int nr)
 513 {
 514         return (unsigned long)sys_call_table[nr];
 515 }
 516
 517 static int __init init_ftrace_syscalls(void)
 518 {
 519         struct syscall_metadata *meta;
 520         unsigned long addr;
 521         int i;
 522
 523         syscalls_metadata = kcalloc(NR_syscalls, sizeof(*syscalls_metadata),
 524                                     GFP_KERNEL);
 525         if (!syscalls_metadata) {
 526                 WARN_ON(1);
 527                 return -ENOMEM;
 528         }
 529
 530         for (i = 0; i < NR_syscalls; i++) {
 531                 addr = arch_syscall_addr(i);
 532                 meta = find_syscall_meta(addr);
 533                 if (!meta)
 534                         continue;
 535
 536                 meta->syscall_nr = i;
 537                 syscalls_metadata[i] = meta;
 538         }
 539
 540         return 0;
 541 }
 542 early_initcall(init_ftrace_syscalls);
 543
 544 #ifdef CONFIG_PERF_EVENTS
 545
 546 static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
 547 static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
 548 static int sys_perf_refcount_enter;
 549 static int sys_perf_refcount_exit;
 550
 551 static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
 552 {
 553         struct syscall_metadata *sys_data;
 554         struct syscall_trace_enter *rec;
 555         struct hlist_head *head;
 556         int syscall_nr;
 557         int rctx;
 558         int size;
 559
 560         syscall_nr = trace_get_syscall_nr(current, regs);
 561         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
 562                 return;
 563         if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
 564                 return;
 565
 566         sys_data = syscall_nr_to_meta(syscall_nr);
 567         if (!sys_data)
 568                 return;
 569
 570         head = this_cpu_ptr(sys_data->enter_event->perf_events);
 571         if (hlist_empty(head))
 572                 return;
 573
 574         /* get the size after alignment with the u32 buffer size field */
 575         size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
 576         size = ALIGN(size + sizeof(u32), sizeof(u64));
 577         size -= sizeof(u32);
 578
 579         rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size,
 580                                 sys_data->enter_event->event.type, regs, &rctx);
 581         if (!rec)
 582                 return;
 583
 584         rec->nr = syscall_nr;
 585         syscall_get_arguments(current, regs, 0, sys_data->nb_args,
 586                                (unsigned long *)&rec->args);
 587         perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 588 }
 589
 590 static int perf_sysenter_enable(struct ftrace_event_call *call)
 591 {
 592         int ret = 0;
 593         int num;
 594
 595         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 596
 597         mutex_lock(&syscall_trace_lock);
 598         if (!sys_perf_refcount_enter)
 599                 ret = register_trace_sys_enter(perf_syscall_enter, NULL);
 600         if (ret) {
 601                 pr_info("event trace: Could not activate"
 602                                 "syscall entry trace point");
 603         } else {
 604                 set_bit(num, enabled_perf_enter_syscalls);
 605                 sys_perf_refcount_enter++;
 606         }
 607         mutex_unlock(&syscall_trace_lock);
 608         return ret;
 609 }
 610
 611 static void perf_sysenter_disable(struct ftrace_event_call *call)
 612 {
 613         int num;
 614
 615         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 616
 617         mutex_lock(&syscall_trace_lock);
 618         sys_perf_refcount_enter--;
 619         clear_bit(num, enabled_perf_enter_syscalls);
 620         if (!sys_perf_refcount_enter)
 621                 unregister_trace_sys_enter(perf_syscall_enter, NULL);
 622         mutex_unlock(&syscall_trace_lock);
 623 }
 624
 625 static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
 626 {
 627         struct syscall_metadata *sys_data;
 628         struct syscall_trace_exit *rec;
 629         struct hlist_head *head;
 630         int syscall_nr;
 631         int rctx;
 632         int size;
 633
 634         syscall_nr = trace_get_syscall_nr(current, regs);
 635         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
 636                 return;
 637         if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
 638                 return;
 639
 640         sys_data = syscall_nr_to_meta(syscall_nr);
 641         if (!sys_data)
 642                 return;
 643
 644         head = this_cpu_ptr(sys_data->exit_event->perf_events);
 645         if (hlist_empty(head))
 646                 return;
 647
 648         /* We can probably do that at build time */
 649         size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
 650         size -= sizeof(u32);
 651
 652         rec = (struct syscall_trace_exit *)perf_trace_buf_prepare(size,
 653                                 sys_data->exit_event->event.type, regs, &rctx);
 654         if (!rec)
 655                 return;
 656
 657         rec->nr = syscall_nr;
 658         rec->ret = syscall_get_return_value(current, regs);
 659         perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
 660 }
 661
 662 static int perf_sysexit_enable(struct ftrace_event_call *call)
 663 {
 664         int ret = 0;
 665         int num;
 666
 667         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 668
 669         mutex_lock(&syscall_trace_lock);
 670         if (!sys_perf_refcount_exit)
 671                 ret = register_trace_sys_exit(perf_syscall_exit, NULL);
 672         if (ret) {
 673                 pr_info("event trace: Could not activate"
 674                                 "syscall exit trace point");
 675         } else {
 676                 set_bit(num, enabled_perf_exit_syscalls);
 677                 sys_perf_refcount_exit++;
 678         }
 679         mutex_unlock(&syscall_trace_lock);
 680         return ret;
 681 }
 682
 683 static void perf_sysexit_disable(struct ftrace_event_call *call)
 684 {
 685         int num;
 686
 687         num = ((struct syscall_metadata *)call->data)->syscall_nr;
 688
 689         mutex_lock(&syscall_trace_lock);
 690         sys_perf_refcount_exit--;
 691         clear_bit(num, enabled_perf_exit_syscalls);
 692         if (!sys_perf_refcount_exit)
 693                 unregister_trace_sys_exit(perf_syscall_exit, NULL);
 694         mutex_unlock(&syscall_trace_lock);
 695 }
 696
 697 #endif /* CONFIG_PERF_EVENTS */
 698
 699 static int syscall_enter_register(struct ftrace_event_call *event,
 700                                  enum trace_reg type, void *data)
 701 {
 702         struct ftrace_event_file *file = data;
 703
 704         switch (type) {
 705         case TRACE_REG_REGISTER:
 706                 return reg_event_syscall_enter(file, event);
 707         case TRACE_REG_UNREGISTER:
 708                 unreg_event_syscall_enter(file, event);
 709                 return 0;
 710
 711 #ifdef CONFIG_PERF_EVENTS
 712         case TRACE_REG_PERF_REGISTER:
 713                 return perf_sysenter_enable(event);
 714         case TRACE_REG_PERF_UNREGISTER:
 715                 perf_sysenter_disable(event);
 716                 return 0;
 717         case TRACE_REG_PERF_OPEN:
 718         case TRACE_REG_PERF_CLOSE:
 719         case TRACE_REG_PERF_ADD:
 720         case TRACE_REG_PERF_DEL:
 721                 return 0;
 722 #endif
 723         }
 724         return 0;
 725 }
 726
 727 static int syscall_exit_register(struct ftrace_event_call *event,
 728                                  enum trace_reg type, void *data)
 729 {
 730         struct ftrace_event_file *file = data;
 731
 732         switch (type) {
 733         case TRACE_REG_REGISTER:
 734                 return reg_event_syscall_exit(file, event);
 735         case TRACE_REG_UNREGISTER:
 736                 unreg_event_syscall_exit(file, event);
 737                 return 0;
 738
 739 #ifdef CONFIG_PERF_EVENTS
 740         case TRACE_REG_PERF_REGISTER:
 741                 return perf_sysexit_enable(event);
 742         case TRACE_REG_PERF_UNREGISTER:
 743                 perf_sysexit_disable(event);
 744                 return 0;
 745         case TRACE_REG_PERF_OPEN:
 746         case TRACE_REG_PERF_CLOSE:
 747         case TRACE_REG_PERF_ADD:
 748         case TRACE_REG_PERF_DEL:
 749                 return 0;
 750 #endif
 751         }
 752         return 0;
 753 }