Merge tag '4.3-rc-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6
[sfrench/cifs-2.6.git] / kernel / trace / trace_syscalls.c
1 // SPDX-License-Identifier: GPL-2.0
2 #include <trace/syscall.h>
3 #include <trace/events/syscalls.h>
4 #include <linux/syscalls.h>
5 #include <linux/slab.h>
6 #include <linux/kernel.h>
7 #include <linux/module.h>       /* for MODULE_NAME_LEN via KSYM_SYMBOL_LEN */
8 #include <linux/ftrace.h>
9 #include <linux/perf_event.h>
10 #include <asm/syscall.h>
11
12 #include "trace_output.h"
13 #include "trace.h"
14
15 static DEFINE_MUTEX(syscall_trace_lock);
16
17 static int syscall_enter_register(struct trace_event_call *event,
18                                  enum trace_reg type, void *data);
19 static int syscall_exit_register(struct trace_event_call *event,
20                                  enum trace_reg type, void *data);
21
22 static struct list_head *
23 syscall_get_enter_fields(struct trace_event_call *call)
24 {
25         struct syscall_metadata *entry = call->data;
26
27         return &entry->enter_fields;
28 }
29
30 extern struct syscall_metadata *__start_syscalls_metadata[];
31 extern struct syscall_metadata *__stop_syscalls_metadata[];
32
33 static struct syscall_metadata **syscalls_metadata;
34
35 #ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
36 static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
37 {
38         /*
39          * Only compare after the "sys" prefix. Archs that use
40          * syscall wrappers may have syscalls symbols aliases prefixed
41          * with ".SyS" or ".sys" instead of "sys", leading to an unwanted
42          * mismatch.
43          */
44         return !strcmp(sym + 3, name + 3);
45 }
46 #endif
47
48 #ifdef ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
49 /*
50  * Some architectures that allow for 32bit applications
51  * to run on a 64bit kernel, do not map the syscalls for
52  * the 32bit tasks the same as they do for 64bit tasks.
53  *
54  *     *cough*x86*cough*
55  *
56  * In such a case, instead of reporting the wrong syscalls,
57  * simply ignore them.
58  *
59  * For an arch to ignore the compat syscalls it needs to
60  * define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS as well as
61  * define the function arch_trace_is_compat_syscall() to let
62  * the tracing system know that it should ignore it.
63  */
64 static int
65 trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs)
66 {
67         if (unlikely(arch_trace_is_compat_syscall(regs)))
68                 return -1;
69
70         return syscall_get_nr(task, regs);
71 }
72 #else
73 static inline int
74 trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs)
75 {
76         return syscall_get_nr(task, regs);
77 }
78 #endif /* ARCH_TRACE_IGNORE_COMPAT_SYSCALLS */
79
80 static __init struct syscall_metadata *
81 find_syscall_meta(unsigned long syscall)
82 {
83         struct syscall_metadata **start;
84         struct syscall_metadata **stop;
85         char str[KSYM_SYMBOL_LEN];
86
87
88         start = __start_syscalls_metadata;
89         stop = __stop_syscalls_metadata;
90         kallsyms_lookup(syscall, NULL, NULL, NULL, str);
91
92         if (arch_syscall_match_sym_name(str, "sys_ni_syscall"))
93                 return NULL;
94
95         for ( ; start < stop; start++) {
96                 if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name))
97                         return *start;
98         }
99         return NULL;
100 }
101
102 static struct syscall_metadata *syscall_nr_to_meta(int nr)
103 {
104         if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
105                 return NULL;
106
107         return syscalls_metadata[nr];
108 }
109
110 const char *get_syscall_name(int syscall)
111 {
112         struct syscall_metadata *entry;
113
114         entry = syscall_nr_to_meta(syscall);
115         if (!entry)
116                 return NULL;
117
118         return entry->name;
119 }
120
121 static enum print_line_t
122 print_syscall_enter(struct trace_iterator *iter, int flags,
123                     struct trace_event *event)
124 {
125         struct trace_array *tr = iter->tr;
126         struct trace_seq *s = &iter->seq;
127         struct trace_entry *ent = iter->ent;
128         struct syscall_trace_enter *trace;
129         struct syscall_metadata *entry;
130         int i, syscall;
131
132         trace = (typeof(trace))ent;
133         syscall = trace->nr;
134         entry = syscall_nr_to_meta(syscall);
135
136         if (!entry)
137                 goto end;
138
139         if (entry->enter_event->event.type != ent->type) {
140                 WARN_ON_ONCE(1);
141                 goto end;
142         }
143
144         trace_seq_printf(s, "%s(", entry->name);
145
146         for (i = 0; i < entry->nb_args; i++) {
147
148                 if (trace_seq_has_overflowed(s))
149                         goto end;
150
151                 /* parameter types */
152                 if (tr->trace_flags & TRACE_ITER_VERBOSE)
153                         trace_seq_printf(s, "%s ", entry->types[i]);
154
155                 /* parameter values */
156                 trace_seq_printf(s, "%s: %lx%s", entry->args[i],
157                                  trace->args[i],
158                                  i == entry->nb_args - 1 ? "" : ", ");
159         }
160
161         trace_seq_putc(s, ')');
162 end:
163         trace_seq_putc(s, '\n');
164
165         return trace_handle_return(s);
166 }
167
168 static enum print_line_t
169 print_syscall_exit(struct trace_iterator *iter, int flags,
170                    struct trace_event *event)
171 {
172         struct trace_seq *s = &iter->seq;
173         struct trace_entry *ent = iter->ent;
174         struct syscall_trace_exit *trace;
175         int syscall;
176         struct syscall_metadata *entry;
177
178         trace = (typeof(trace))ent;
179         syscall = trace->nr;
180         entry = syscall_nr_to_meta(syscall);
181
182         if (!entry) {
183                 trace_seq_putc(s, '\n');
184                 goto out;
185         }
186
187         if (entry->exit_event->event.type != ent->type) {
188                 WARN_ON_ONCE(1);
189                 return TRACE_TYPE_UNHANDLED;
190         }
191
192         trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
193                                 trace->ret);
194
195  out:
196         return trace_handle_return(s);
197 }
198
199 extern char *__bad_type_size(void);
200
201 #define SYSCALL_FIELD(type, field, name)                                \
202         sizeof(type) != sizeof(trace.field) ?                           \
203                 __bad_type_size() :                                     \
204                 #type, #name, offsetof(typeof(trace), field),           \
205                 sizeof(trace.field), is_signed_type(type)
206
207 static int __init
208 __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 __init set_syscall_print_fmt(struct trace_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 __init free_syscall_print_fmt(struct trace_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 __init syscall_enter_define_fields(struct trace_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, __syscall_nr),
277                                  FILTER_OTHER);
278         if (ret)
279                 return ret;
280
281         for (i = 0; i < meta->nb_args; i++) {
282                 ret = trace_define_field(call, meta->types[i],
283                                          meta->args[i], offset,
284                                          sizeof(unsigned long), 0,
285                                          FILTER_OTHER);
286                 offset += sizeof(unsigned long);
287         }
288
289         return ret;
290 }
291
292 static int __init syscall_exit_define_fields(struct trace_event_call *call)
293 {
294         struct syscall_trace_exit trace;
295         int ret;
296
297         ret = trace_define_field(call, SYSCALL_FIELD(int, nr, __syscall_nr),
298                                  FILTER_OTHER);
299         if (ret)
300                 return ret;
301
302         ret = trace_define_field(call, SYSCALL_FIELD(long, ret, ret),
303                                  FILTER_OTHER);
304
305         return ret;
306 }
307
308 static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
309 {
310         struct trace_array *tr = data;
311         struct trace_event_file *trace_file;
312         struct syscall_trace_enter *entry;
313         struct syscall_metadata *sys_data;
314         struct ring_buffer_event *event;
315         struct ring_buffer *buffer;
316         unsigned long irq_flags;
317         unsigned long args[6];
318         int pc;
319         int syscall_nr;
320         int size;
321
322         syscall_nr = trace_get_syscall_nr(current, regs);
323         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
324                 return;
325
326         /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE) */
327         trace_file = rcu_dereference_sched(tr->enter_syscall_files[syscall_nr]);
328         if (!trace_file)
329                 return;
330
331         if (trace_trigger_soft_disabled(trace_file))
332                 return;
333
334         sys_data = syscall_nr_to_meta(syscall_nr);
335         if (!sys_data)
336                 return;
337
338         size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
339
340         local_save_flags(irq_flags);
341         pc = preempt_count();
342
343         buffer = tr->trace_buffer.buffer;
344         event = trace_buffer_lock_reserve(buffer,
345                         sys_data->enter_event->event.type, size, irq_flags, pc);
346         if (!event)
347                 return;
348
349         entry = ring_buffer_event_data(event);
350         entry->nr = syscall_nr;
351         syscall_get_arguments(current, regs, args);
352         memcpy(entry->args, args, sizeof(unsigned long) * sys_data->nb_args);
353
354         event_trigger_unlock_commit(trace_file, buffer, event, entry,
355                                     irq_flags, pc);
356 }
357
358 static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
359 {
360         struct trace_array *tr = data;
361         struct trace_event_file *trace_file;
362         struct syscall_trace_exit *entry;
363         struct syscall_metadata *sys_data;
364         struct ring_buffer_event *event;
365         struct ring_buffer *buffer;
366         unsigned long irq_flags;
367         int pc;
368         int syscall_nr;
369
370         syscall_nr = trace_get_syscall_nr(current, regs);
371         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
372                 return;
373
374         /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE()) */
375         trace_file = rcu_dereference_sched(tr->exit_syscall_files[syscall_nr]);
376         if (!trace_file)
377                 return;
378
379         if (trace_trigger_soft_disabled(trace_file))
380                 return;
381
382         sys_data = syscall_nr_to_meta(syscall_nr);
383         if (!sys_data)
384                 return;
385
386         local_save_flags(irq_flags);
387         pc = preempt_count();
388
389         buffer = tr->trace_buffer.buffer;
390         event = trace_buffer_lock_reserve(buffer,
391                         sys_data->exit_event->event.type, sizeof(*entry),
392                         irq_flags, pc);
393         if (!event)
394                 return;
395
396         entry = ring_buffer_event_data(event);
397         entry->nr = syscall_nr;
398         entry->ret = syscall_get_return_value(current, regs);
399
400         event_trigger_unlock_commit(trace_file, buffer, event, entry,
401                                     irq_flags, pc);
402 }
403
404 static int reg_event_syscall_enter(struct trace_event_file *file,
405                                    struct trace_event_call *call)
406 {
407         struct trace_array *tr = file->tr;
408         int ret = 0;
409         int num;
410
411         num = ((struct syscall_metadata *)call->data)->syscall_nr;
412         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
413                 return -ENOSYS;
414         mutex_lock(&syscall_trace_lock);
415         if (!tr->sys_refcount_enter)
416                 ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
417         if (!ret) {
418                 rcu_assign_pointer(tr->enter_syscall_files[num], file);
419                 tr->sys_refcount_enter++;
420         }
421         mutex_unlock(&syscall_trace_lock);
422         return ret;
423 }
424
425 static void unreg_event_syscall_enter(struct trace_event_file *file,
426                                       struct trace_event_call *call)
427 {
428         struct trace_array *tr = file->tr;
429         int num;
430
431         num = ((struct syscall_metadata *)call->data)->syscall_nr;
432         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
433                 return;
434         mutex_lock(&syscall_trace_lock);
435         tr->sys_refcount_enter--;
436         RCU_INIT_POINTER(tr->enter_syscall_files[num], NULL);
437         if (!tr->sys_refcount_enter)
438                 unregister_trace_sys_enter(ftrace_syscall_enter, tr);
439         mutex_unlock(&syscall_trace_lock);
440 }
441
442 static int reg_event_syscall_exit(struct trace_event_file *file,
443                                   struct trace_event_call *call)
444 {
445         struct trace_array *tr = file->tr;
446         int ret = 0;
447         int num;
448
449         num = ((struct syscall_metadata *)call->data)->syscall_nr;
450         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
451                 return -ENOSYS;
452         mutex_lock(&syscall_trace_lock);
453         if (!tr->sys_refcount_exit)
454                 ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
455         if (!ret) {
456                 rcu_assign_pointer(tr->exit_syscall_files[num], file);
457                 tr->sys_refcount_exit++;
458         }
459         mutex_unlock(&syscall_trace_lock);
460         return ret;
461 }
462
463 static void unreg_event_syscall_exit(struct trace_event_file *file,
464                                      struct trace_event_call *call)
465 {
466         struct trace_array *tr = file->tr;
467         int num;
468
469         num = ((struct syscall_metadata *)call->data)->syscall_nr;
470         if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
471                 return;
472         mutex_lock(&syscall_trace_lock);
473         tr->sys_refcount_exit--;
474         RCU_INIT_POINTER(tr->exit_syscall_files[num], NULL);
475         if (!tr->sys_refcount_exit)
476                 unregister_trace_sys_exit(ftrace_syscall_exit, tr);
477         mutex_unlock(&syscall_trace_lock);
478 }
479
480 static int __init init_syscall_trace(struct trace_event_call *call)
481 {
482         int id;
483         int num;
484
485         num = ((struct syscall_metadata *)call->data)->syscall_nr;
486         if (num < 0 || num >= NR_syscalls) {
487                 pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
488                                 ((struct syscall_metadata *)call->data)->name);
489                 return -ENOSYS;
490         }
491
492         if (set_syscall_print_fmt(call) < 0)
493                 return -ENOMEM;
494
495         id = trace_event_raw_init(call);
496
497         if (id < 0) {
498                 free_syscall_print_fmt(call);
499                 return id;
500         }
501
502         return id;
503 }
504
505 struct trace_event_functions enter_syscall_print_funcs = {
506         .trace          = print_syscall_enter,
507 };
508
509 struct trace_event_functions exit_syscall_print_funcs = {
510         .trace          = print_syscall_exit,
511 };
512
513 struct trace_event_class __refdata event_class_syscall_enter = {
514         .system         = "syscalls",
515         .reg            = syscall_enter_register,
516         .define_fields  = syscall_enter_define_fields,
517         .get_fields     = syscall_get_enter_fields,
518         .raw_init       = init_syscall_trace,
519 };
520
521 struct trace_event_class __refdata event_class_syscall_exit = {
522         .system         = "syscalls",
523         .reg            = syscall_exit_register,
524         .define_fields  = syscall_exit_define_fields,
525         .fields         = LIST_HEAD_INIT(event_class_syscall_exit.fields),
526         .raw_init       = init_syscall_trace,
527 };
528
529 unsigned long __init __weak arch_syscall_addr(int nr)
530 {
531         return (unsigned long)sys_call_table[nr];
532 }
533
534 void __init init_ftrace_syscalls(void)
535 {
536         struct syscall_metadata *meta;
537         unsigned long addr;
538         int i;
539
540         syscalls_metadata = kcalloc(NR_syscalls, sizeof(*syscalls_metadata),
541                                     GFP_KERNEL);
542         if (!syscalls_metadata) {
543                 WARN_ON(1);
544                 return;
545         }
546
547         for (i = 0; i < NR_syscalls; i++) {
548                 addr = arch_syscall_addr(i);
549                 meta = find_syscall_meta(addr);
550                 if (!meta)
551                         continue;
552
553                 meta->syscall_nr = i;
554                 syscalls_metadata[i] = meta;
555         }
556 }
557
558 #ifdef CONFIG_PERF_EVENTS
559
560 static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
561 static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
562 static int sys_perf_refcount_enter;
563 static int sys_perf_refcount_exit;
564
565 static int perf_call_bpf_enter(struct trace_event_call *call, struct pt_regs *regs,
566                                struct syscall_metadata *sys_data,
567                                struct syscall_trace_enter *rec)
568 {
569         struct syscall_tp_t {
570                 unsigned long long regs;
571                 unsigned long syscall_nr;
572                 unsigned long args[SYSCALL_DEFINE_MAXARGS];
573         } param;
574         int i;
575
576         *(struct pt_regs **)&param = regs;
577         param.syscall_nr = rec->nr;
578         for (i = 0; i < sys_data->nb_args; i++)
579                 param.args[i] = rec->args[i];
580         return trace_call_bpf(call, &param);
581 }
582
583 static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
584 {
585         struct syscall_metadata *sys_data;
586         struct syscall_trace_enter *rec;
587         struct hlist_head *head;
588         unsigned long args[6];
589         bool valid_prog_array;
590         int syscall_nr;
591         int rctx;
592         int size;
593
594         syscall_nr = trace_get_syscall_nr(current, regs);
595         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
596                 return;
597         if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
598                 return;
599
600         sys_data = syscall_nr_to_meta(syscall_nr);
601         if (!sys_data)
602                 return;
603
604         head = this_cpu_ptr(sys_data->enter_event->perf_events);
605         valid_prog_array = bpf_prog_array_valid(sys_data->enter_event);
606         if (!valid_prog_array && hlist_empty(head))
607                 return;
608
609         /* get the size after alignment with the u32 buffer size field */
610         size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
611         size = ALIGN(size + sizeof(u32), sizeof(u64));
612         size -= sizeof(u32);
613
614         rec = perf_trace_buf_alloc(size, NULL, &rctx);
615         if (!rec)
616                 return;
617
618         rec->nr = syscall_nr;
619         syscall_get_arguments(current, regs, args);
620         memcpy(&rec->args, args, sizeof(unsigned long) * sys_data->nb_args);
621
622         if ((valid_prog_array &&
623              !perf_call_bpf_enter(sys_data->enter_event, regs, sys_data, rec)) ||
624             hlist_empty(head)) {
625                 perf_swevent_put_recursion_context(rctx);
626                 return;
627         }
628
629         perf_trace_buf_submit(rec, size, rctx,
630                               sys_data->enter_event->event.type, 1, regs,
631                               head, NULL);
632 }
633
634 static int perf_sysenter_enable(struct trace_event_call *call)
635 {
636         int ret = 0;
637         int num;
638
639         num = ((struct syscall_metadata *)call->data)->syscall_nr;
640
641         mutex_lock(&syscall_trace_lock);
642         if (!sys_perf_refcount_enter)
643                 ret = register_trace_sys_enter(perf_syscall_enter, NULL);
644         if (ret) {
645                 pr_info("event trace: Could not activate syscall entry trace point");
646         } else {
647                 set_bit(num, enabled_perf_enter_syscalls);
648                 sys_perf_refcount_enter++;
649         }
650         mutex_unlock(&syscall_trace_lock);
651         return ret;
652 }
653
654 static void perf_sysenter_disable(struct trace_event_call *call)
655 {
656         int num;
657
658         num = ((struct syscall_metadata *)call->data)->syscall_nr;
659
660         mutex_lock(&syscall_trace_lock);
661         sys_perf_refcount_enter--;
662         clear_bit(num, enabled_perf_enter_syscalls);
663         if (!sys_perf_refcount_enter)
664                 unregister_trace_sys_enter(perf_syscall_enter, NULL);
665         mutex_unlock(&syscall_trace_lock);
666 }
667
668 static int perf_call_bpf_exit(struct trace_event_call *call, struct pt_regs *regs,
669                               struct syscall_trace_exit *rec)
670 {
671         struct syscall_tp_t {
672                 unsigned long long regs;
673                 unsigned long syscall_nr;
674                 unsigned long ret;
675         } param;
676
677         *(struct pt_regs **)&param = regs;
678         param.syscall_nr = rec->nr;
679         param.ret = rec->ret;
680         return trace_call_bpf(call, &param);
681 }
682
683 static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
684 {
685         struct syscall_metadata *sys_data;
686         struct syscall_trace_exit *rec;
687         struct hlist_head *head;
688         bool valid_prog_array;
689         int syscall_nr;
690         int rctx;
691         int size;
692
693         syscall_nr = trace_get_syscall_nr(current, regs);
694         if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
695                 return;
696         if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
697                 return;
698
699         sys_data = syscall_nr_to_meta(syscall_nr);
700         if (!sys_data)
701                 return;
702
703         head = this_cpu_ptr(sys_data->exit_event->perf_events);
704         valid_prog_array = bpf_prog_array_valid(sys_data->exit_event);
705         if (!valid_prog_array && hlist_empty(head))
706                 return;
707
708         /* We can probably do that at build time */
709         size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
710         size -= sizeof(u32);
711
712         rec = perf_trace_buf_alloc(size, NULL, &rctx);
713         if (!rec)
714                 return;
715
716         rec->nr = syscall_nr;
717         rec->ret = syscall_get_return_value(current, regs);
718
719         if ((valid_prog_array &&
720              !perf_call_bpf_exit(sys_data->exit_event, regs, rec)) ||
721             hlist_empty(head)) {
722                 perf_swevent_put_recursion_context(rctx);
723                 return;
724         }
725
726         perf_trace_buf_submit(rec, size, rctx, sys_data->exit_event->event.type,
727                               1, regs, head, NULL);
728 }
729
730 static int perf_sysexit_enable(struct trace_event_call *call)
731 {
732         int ret = 0;
733         int num;
734
735         num = ((struct syscall_metadata *)call->data)->syscall_nr;
736
737         mutex_lock(&syscall_trace_lock);
738         if (!sys_perf_refcount_exit)
739                 ret = register_trace_sys_exit(perf_syscall_exit, NULL);
740         if (ret) {
741                 pr_info("event trace: Could not activate syscall exit trace point");
742         } else {
743                 set_bit(num, enabled_perf_exit_syscalls);
744                 sys_perf_refcount_exit++;
745         }
746         mutex_unlock(&syscall_trace_lock);
747         return ret;
748 }
749
750 static void perf_sysexit_disable(struct trace_event_call *call)
751 {
752         int num;
753
754         num = ((struct syscall_metadata *)call->data)->syscall_nr;
755
756         mutex_lock(&syscall_trace_lock);
757         sys_perf_refcount_exit--;
758         clear_bit(num, enabled_perf_exit_syscalls);
759         if (!sys_perf_refcount_exit)
760                 unregister_trace_sys_exit(perf_syscall_exit, NULL);
761         mutex_unlock(&syscall_trace_lock);
762 }
763
764 #endif /* CONFIG_PERF_EVENTS */
765
766 static int syscall_enter_register(struct trace_event_call *event,
767                                  enum trace_reg type, void *data)
768 {
769         struct trace_event_file *file = data;
770
771         switch (type) {
772         case TRACE_REG_REGISTER:
773                 return reg_event_syscall_enter(file, event);
774         case TRACE_REG_UNREGISTER:
775                 unreg_event_syscall_enter(file, event);
776                 return 0;
777
778 #ifdef CONFIG_PERF_EVENTS
779         case TRACE_REG_PERF_REGISTER:
780                 return perf_sysenter_enable(event);
781         case TRACE_REG_PERF_UNREGISTER:
782                 perf_sysenter_disable(event);
783                 return 0;
784         case TRACE_REG_PERF_OPEN:
785         case TRACE_REG_PERF_CLOSE:
786         case TRACE_REG_PERF_ADD:
787         case TRACE_REG_PERF_DEL:
788                 return 0;
789 #endif
790         }
791         return 0;
792 }
793
794 static int syscall_exit_register(struct trace_event_call *event,
795                                  enum trace_reg type, void *data)
796 {
797         struct trace_event_file *file = data;
798
799         switch (type) {
800         case TRACE_REG_REGISTER:
801                 return reg_event_syscall_exit(file, event);
802         case TRACE_REG_UNREGISTER:
803                 unreg_event_syscall_exit(file, event);
804                 return 0;
805
806 #ifdef CONFIG_PERF_EVENTS
807         case TRACE_REG_PERF_REGISTER:
808                 return perf_sysexit_enable(event);
809         case TRACE_REG_PERF_UNREGISTER:
810                 perf_sysexit_disable(event);
811                 return 0;
812         case TRACE_REG_PERF_OPEN:
813         case TRACE_REG_PERF_CLOSE:
814         case TRACE_REG_PERF_ADD:
815         case TRACE_REG_PERF_DEL:
816                 return 0;
817 #endif
818         }
819         return 0;
820 }