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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 <linux/xarray.h>
11#include <asm/syscall.h>
12
13#include "trace_output.h"
14#include "trace.h"
15
16static DEFINE_MUTEX(syscall_trace_lock);
17
18static int syscall_enter_register(struct trace_event_call *event,
19 enum trace_reg type, void *data);
20static int syscall_exit_register(struct trace_event_call *event,
21 enum trace_reg type, void *data);
22
23static struct list_head *
24syscall_get_enter_fields(struct trace_event_call *call)
25{
26 struct syscall_metadata *entry = call->data;
27
28 return &entry->enter_fields;
29}
30
31extern struct syscall_metadata *__start_syscalls_metadata[];
32extern struct syscall_metadata *__stop_syscalls_metadata[];
33
34static DEFINE_XARRAY(syscalls_metadata_sparse);
35static struct syscall_metadata **syscalls_metadata;
36
37#ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
38static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
39{
40 /*
41 * Only compare after the "sys" prefix. Archs that use
42 * syscall wrappers may have syscalls symbols aliases prefixed
43 * with ".SyS" or ".sys" instead of "sys", leading to an unwanted
44 * mismatch.
45 */
46 return !strcmp(sym + 3, name + 3);
47}
48#endif
49
50#ifdef ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
51/*
52 * Some architectures that allow for 32bit applications
53 * to run on a 64bit kernel, do not map the syscalls for
54 * the 32bit tasks the same as they do for 64bit tasks.
55 *
56 * *cough*x86*cough*
57 *
58 * In such a case, instead of reporting the wrong syscalls,
59 * simply ignore them.
60 *
61 * For an arch to ignore the compat syscalls it needs to
62 * define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS as well as
63 * define the function arch_trace_is_compat_syscall() to let
64 * the tracing system know that it should ignore it.
65 */
66static int
67trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs)
68{
69 if (unlikely(arch_trace_is_compat_syscall(regs)))
70 return -1;
71
72 return syscall_get_nr(task, regs);
73}
74#else
75static inline int
76trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs)
77{
78 return syscall_get_nr(task, regs);
79}
80#endif /* ARCH_TRACE_IGNORE_COMPAT_SYSCALLS */
81
82static __init struct syscall_metadata *
83find_syscall_meta(unsigned long syscall)
84{
85 struct syscall_metadata **start;
86 struct syscall_metadata **stop;
87 char str[KSYM_SYMBOL_LEN];
88
89
90 start = __start_syscalls_metadata;
91 stop = __stop_syscalls_metadata;
92 kallsyms_lookup(syscall, NULL, NULL, NULL, str);
93
94 if (arch_syscall_match_sym_name(str, "sys_ni_syscall"))
95 return NULL;
96
97 for ( ; start < stop; start++) {
98 if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name))
99 return *start;
100 }
101 return NULL;
102}
103
104static struct syscall_metadata *syscall_nr_to_meta(int nr)
105{
106 if (IS_ENABLED(CONFIG_HAVE_SPARSE_SYSCALL_NR))
107 return xa_load(&syscalls_metadata_sparse, (unsigned long)nr);
108
109 if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
110 return NULL;
111
112 return syscalls_metadata[nr];
113}
114
115const char *get_syscall_name(int syscall)
116{
117 struct syscall_metadata *entry;
118
119 entry = syscall_nr_to_meta(syscall);
120 if (!entry)
121 return NULL;
122
123 return entry->name;
124}
125
126static enum print_line_t
127print_syscall_enter(struct trace_iterator *iter, int flags,
128 struct trace_event *event)
129{
130 struct trace_array *tr = iter->tr;
131 struct trace_seq *s = &iter->seq;
132 struct trace_entry *ent = iter->ent;
133 struct syscall_trace_enter *trace;
134 struct syscall_metadata *entry;
135 int i, syscall;
136
137 trace = (typeof(trace))ent;
138 syscall = trace->nr;
139 entry = syscall_nr_to_meta(syscall);
140
141 if (!entry)
142 goto end;
143
144 if (entry->enter_event->event.type != ent->type) {
145 WARN_ON_ONCE(1);
146 goto end;
147 }
148
149 trace_seq_printf(s, "%s(", entry->name);
150
151 for (i = 0; i < entry->nb_args; i++) {
152
153 if (trace_seq_has_overflowed(s))
154 goto end;
155
156 /* parameter types */
157 if (tr && tr->trace_flags & TRACE_ITER_VERBOSE)
158 trace_seq_printf(s, "%s ", entry->types[i]);
159
160 /* parameter values */
161 trace_seq_printf(s, "%s: %lx%s", entry->args[i],
162 trace->args[i],
163 i == entry->nb_args - 1 ? "" : ", ");
164 }
165
166 trace_seq_putc(s, ')');
167end:
168 trace_seq_putc(s, '\n');
169
170 return trace_handle_return(s);
171}
172
173static enum print_line_t
174print_syscall_exit(struct trace_iterator *iter, int flags,
175 struct trace_event *event)
176{
177 struct trace_seq *s = &iter->seq;
178 struct trace_entry *ent = iter->ent;
179 struct syscall_trace_exit *trace;
180 int syscall;
181 struct syscall_metadata *entry;
182
183 trace = (typeof(trace))ent;
184 syscall = trace->nr;
185 entry = syscall_nr_to_meta(syscall);
186
187 if (!entry) {
188 trace_seq_putc(s, '\n');
189 goto out;
190 }
191
192 if (entry->exit_event->event.type != ent->type) {
193 WARN_ON_ONCE(1);
194 return TRACE_TYPE_UNHANDLED;
195 }
196
197 trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
198 trace->ret);
199
200 out:
201 return trace_handle_return(s);
202}
203
204#define SYSCALL_FIELD(_type, _name) { \
205 .type = #_type, .name = #_name, \
206 .size = sizeof(_type), .align = __alignof__(_type), \
207 .is_signed = is_signed_type(_type), .filter_type = FILTER_OTHER }
208
209static int __init
210__set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
211{
212 int i;
213 int pos = 0;
214
215 /* When len=0, we just calculate the needed length */
216#define LEN_OR_ZERO (len ? len - pos : 0)
217
218 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
219 for (i = 0; i < entry->nb_args; i++) {
220 pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
221 entry->args[i], sizeof(unsigned long),
222 i == entry->nb_args - 1 ? "" : ", ");
223 }
224 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
225
226 for (i = 0; i < entry->nb_args; i++) {
227 pos += snprintf(buf + pos, LEN_OR_ZERO,
228 ", ((unsigned long)(REC->%s))", entry->args[i]);
229 }
230
231#undef LEN_OR_ZERO
232
233 /* return the length of print_fmt */
234 return pos;
235}
236
237static int __init set_syscall_print_fmt(struct trace_event_call *call)
238{
239 char *print_fmt;
240 int len;
241 struct syscall_metadata *entry = call->data;
242
243 if (entry->enter_event != call) {
244 call->print_fmt = "\"0x%lx\", REC->ret";
245 return 0;
246 }
247
248 /* First: called with 0 length to calculate the needed length */
249 len = __set_enter_print_fmt(entry, NULL, 0);
250
251 print_fmt = kmalloc(len + 1, GFP_KERNEL);
252 if (!print_fmt)
253 return -ENOMEM;
254
255 /* Second: actually write the @print_fmt */
256 __set_enter_print_fmt(entry, print_fmt, len + 1);
257 call->print_fmt = print_fmt;
258
259 return 0;
260}
261
262static void __init free_syscall_print_fmt(struct trace_event_call *call)
263{
264 struct syscall_metadata *entry = call->data;
265
266 if (entry->enter_event == call)
267 kfree(call->print_fmt);
268}
269
270static int __init syscall_enter_define_fields(struct trace_event_call *call)
271{
272 struct syscall_trace_enter trace;
273 struct syscall_metadata *meta = call->data;
274 int offset = offsetof(typeof(trace), args);
275 int ret = 0;
276 int i;
277
278 for (i = 0; i < meta->nb_args; i++) {
279 ret = trace_define_field(call, meta->types[i],
280 meta->args[i], offset,
281 sizeof(unsigned long), 0,
282 FILTER_OTHER);
283 if (ret)
284 break;
285 offset += sizeof(unsigned long);
286 }
287
288 return ret;
289}
290
291static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
292{
293 struct trace_array *tr = data;
294 struct trace_event_file *trace_file;
295 struct syscall_trace_enter *entry;
296 struct syscall_metadata *sys_data;
297 struct trace_event_buffer fbuffer;
298 unsigned long args[6];
299 int syscall_nr;
300 int size;
301
302 syscall_nr = trace_get_syscall_nr(current, regs);
303 if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
304 return;
305
306 /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE) */
307 trace_file = rcu_dereference_sched(tr->enter_syscall_files[syscall_nr]);
308 if (!trace_file)
309 return;
310
311 if (trace_trigger_soft_disabled(trace_file))
312 return;
313
314 sys_data = syscall_nr_to_meta(syscall_nr);
315 if (!sys_data)
316 return;
317
318 size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
319
320 entry = trace_event_buffer_reserve(&fbuffer, trace_file, size);
321 if (!entry)
322 return;
323
324 entry = ring_buffer_event_data(fbuffer.event);
325 entry->nr = syscall_nr;
326 syscall_get_arguments(current, regs, args);
327 memcpy(entry->args, args, sizeof(unsigned long) * sys_data->nb_args);
328
329 trace_event_buffer_commit(&fbuffer);
330}
331
332static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
333{
334 struct trace_array *tr = data;
335 struct trace_event_file *trace_file;
336 struct syscall_trace_exit *entry;
337 struct syscall_metadata *sys_data;
338 struct trace_event_buffer fbuffer;
339 int syscall_nr;
340
341 syscall_nr = trace_get_syscall_nr(current, regs);
342 if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
343 return;
344
345 /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE()) */
346 trace_file = rcu_dereference_sched(tr->exit_syscall_files[syscall_nr]);
347 if (!trace_file)
348 return;
349
350 if (trace_trigger_soft_disabled(trace_file))
351 return;
352
353 sys_data = syscall_nr_to_meta(syscall_nr);
354 if (!sys_data)
355 return;
356
357 entry = trace_event_buffer_reserve(&fbuffer, trace_file, sizeof(*entry));
358 if (!entry)
359 return;
360
361 entry = ring_buffer_event_data(fbuffer.event);
362 entry->nr = syscall_nr;
363 entry->ret = syscall_get_return_value(current, regs);
364
365 trace_event_buffer_commit(&fbuffer);
366}
367
368static int reg_event_syscall_enter(struct trace_event_file *file,
369 struct trace_event_call *call)
370{
371 struct trace_array *tr = file->tr;
372 int ret = 0;
373 int num;
374
375 num = ((struct syscall_metadata *)call->data)->syscall_nr;
376 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
377 return -ENOSYS;
378 mutex_lock(&syscall_trace_lock);
379 if (!tr->sys_refcount_enter)
380 ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
381 if (!ret) {
382 rcu_assign_pointer(tr->enter_syscall_files[num], file);
383 tr->sys_refcount_enter++;
384 }
385 mutex_unlock(&syscall_trace_lock);
386 return ret;
387}
388
389static void unreg_event_syscall_enter(struct trace_event_file *file,
390 struct trace_event_call *call)
391{
392 struct trace_array *tr = file->tr;
393 int num;
394
395 num = ((struct syscall_metadata *)call->data)->syscall_nr;
396 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
397 return;
398 mutex_lock(&syscall_trace_lock);
399 tr->sys_refcount_enter--;
400 RCU_INIT_POINTER(tr->enter_syscall_files[num], NULL);
401 if (!tr->sys_refcount_enter)
402 unregister_trace_sys_enter(ftrace_syscall_enter, tr);
403 mutex_unlock(&syscall_trace_lock);
404}
405
406static int reg_event_syscall_exit(struct trace_event_file *file,
407 struct trace_event_call *call)
408{
409 struct trace_array *tr = file->tr;
410 int ret = 0;
411 int num;
412
413 num = ((struct syscall_metadata *)call->data)->syscall_nr;
414 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
415 return -ENOSYS;
416 mutex_lock(&syscall_trace_lock);
417 if (!tr->sys_refcount_exit)
418 ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
419 if (!ret) {
420 rcu_assign_pointer(tr->exit_syscall_files[num], file);
421 tr->sys_refcount_exit++;
422 }
423 mutex_unlock(&syscall_trace_lock);
424 return ret;
425}
426
427static void unreg_event_syscall_exit(struct trace_event_file *file,
428 struct trace_event_call *call)
429{
430 struct trace_array *tr = file->tr;
431 int num;
432
433 num = ((struct syscall_metadata *)call->data)->syscall_nr;
434 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
435 return;
436 mutex_lock(&syscall_trace_lock);
437 tr->sys_refcount_exit--;
438 RCU_INIT_POINTER(tr->exit_syscall_files[num], NULL);
439 if (!tr->sys_refcount_exit)
440 unregister_trace_sys_exit(ftrace_syscall_exit, tr);
441 mutex_unlock(&syscall_trace_lock);
442}
443
444static int __init init_syscall_trace(struct trace_event_call *call)
445{
446 int id;
447 int num;
448
449 num = ((struct syscall_metadata *)call->data)->syscall_nr;
450 if (num < 0 || num >= NR_syscalls) {
451 pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
452 ((struct syscall_metadata *)call->data)->name);
453 return -ENOSYS;
454 }
455
456 if (set_syscall_print_fmt(call) < 0)
457 return -ENOMEM;
458
459 id = trace_event_raw_init(call);
460
461 if (id < 0) {
462 free_syscall_print_fmt(call);
463 return id;
464 }
465
466 return id;
467}
468
469static struct trace_event_fields __refdata syscall_enter_fields_array[] = {
470 SYSCALL_FIELD(int, __syscall_nr),
471 { .type = TRACE_FUNCTION_TYPE,
472 .define_fields = syscall_enter_define_fields },
473 {}
474};
475
476struct trace_event_functions enter_syscall_print_funcs = {
477 .trace = print_syscall_enter,
478};
479
480struct trace_event_functions exit_syscall_print_funcs = {
481 .trace = print_syscall_exit,
482};
483
484struct trace_event_class __refdata event_class_syscall_enter = {
485 .system = "syscalls",
486 .reg = syscall_enter_register,
487 .fields_array = syscall_enter_fields_array,
488 .get_fields = syscall_get_enter_fields,
489 .raw_init = init_syscall_trace,
490};
491
492struct trace_event_class __refdata event_class_syscall_exit = {
493 .system = "syscalls",
494 .reg = syscall_exit_register,
495 .fields_array = (struct trace_event_fields[]){
496 SYSCALL_FIELD(int, __syscall_nr),
497 SYSCALL_FIELD(long, ret),
498 {}
499 },
500 .fields = LIST_HEAD_INIT(event_class_syscall_exit.fields),
501 .raw_init = init_syscall_trace,
502};
503
504unsigned long __init __weak arch_syscall_addr(int nr)
505{
506 return (unsigned long)sys_call_table[nr];
507}
508
509void __init init_ftrace_syscalls(void)
510{
511 struct syscall_metadata *meta;
512 unsigned long addr;
513 int i;
514 void *ret;
515
516 if (!IS_ENABLED(CONFIG_HAVE_SPARSE_SYSCALL_NR)) {
517 syscalls_metadata = kcalloc(NR_syscalls,
518 sizeof(*syscalls_metadata),
519 GFP_KERNEL);
520 if (!syscalls_metadata) {
521 WARN_ON(1);
522 return;
523 }
524 }
525
526 for (i = 0; i < NR_syscalls; i++) {
527 addr = arch_syscall_addr(i);
528 meta = find_syscall_meta(addr);
529 if (!meta)
530 continue;
531
532 meta->syscall_nr = i;
533
534 if (!IS_ENABLED(CONFIG_HAVE_SPARSE_SYSCALL_NR)) {
535 syscalls_metadata[i] = meta;
536 } else {
537 ret = xa_store(&syscalls_metadata_sparse, i, meta,
538 GFP_KERNEL);
539 WARN(xa_is_err(ret),
540 "Syscall memory allocation failed\n");
541 }
542
543 }
544}
545
546#ifdef CONFIG_PERF_EVENTS
547
548static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
549static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
550static int sys_perf_refcount_enter;
551static int sys_perf_refcount_exit;
552
553static int perf_call_bpf_enter(struct trace_event_call *call, struct pt_regs *regs,
554 struct syscall_metadata *sys_data,
555 struct syscall_trace_enter *rec)
556{
557 struct syscall_tp_t {
558 unsigned long long regs;
559 unsigned long syscall_nr;
560 unsigned long args[SYSCALL_DEFINE_MAXARGS];
561 } param;
562 int i;
563
564 *(struct pt_regs **)¶m = regs;
565 param.syscall_nr = rec->nr;
566 for (i = 0; i < sys_data->nb_args; i++)
567 param.args[i] = rec->args[i];
568 return trace_call_bpf(call, ¶m);
569}
570
571static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
572{
573 struct syscall_metadata *sys_data;
574 struct syscall_trace_enter *rec;
575 struct hlist_head *head;
576 unsigned long args[6];
577 bool valid_prog_array;
578 int syscall_nr;
579 int rctx;
580 int size;
581
582 syscall_nr = trace_get_syscall_nr(current, regs);
583 if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
584 return;
585 if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
586 return;
587
588 sys_data = syscall_nr_to_meta(syscall_nr);
589 if (!sys_data)
590 return;
591
592 head = this_cpu_ptr(sys_data->enter_event->perf_events);
593 valid_prog_array = bpf_prog_array_valid(sys_data->enter_event);
594 if (!valid_prog_array && hlist_empty(head))
595 return;
596
597 /* get the size after alignment with the u32 buffer size field */
598 size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
599 size = ALIGN(size + sizeof(u32), sizeof(u64));
600 size -= sizeof(u32);
601
602 rec = perf_trace_buf_alloc(size, NULL, &rctx);
603 if (!rec)
604 return;
605
606 rec->nr = syscall_nr;
607 syscall_get_arguments(current, regs, args);
608 memcpy(&rec->args, args, sizeof(unsigned long) * sys_data->nb_args);
609
610 if ((valid_prog_array &&
611 !perf_call_bpf_enter(sys_data->enter_event, regs, sys_data, rec)) ||
612 hlist_empty(head)) {
613 perf_swevent_put_recursion_context(rctx);
614 return;
615 }
616
617 perf_trace_buf_submit(rec, size, rctx,
618 sys_data->enter_event->event.type, 1, regs,
619 head, NULL);
620}
621
622static int perf_sysenter_enable(struct trace_event_call *call)
623{
624 int ret = 0;
625 int num;
626
627 num = ((struct syscall_metadata *)call->data)->syscall_nr;
628
629 mutex_lock(&syscall_trace_lock);
630 if (!sys_perf_refcount_enter)
631 ret = register_trace_sys_enter(perf_syscall_enter, NULL);
632 if (ret) {
633 pr_info("event trace: Could not activate syscall entry trace point");
634 } else {
635 set_bit(num, enabled_perf_enter_syscalls);
636 sys_perf_refcount_enter++;
637 }
638 mutex_unlock(&syscall_trace_lock);
639 return ret;
640}
641
642static void perf_sysenter_disable(struct trace_event_call *call)
643{
644 int num;
645
646 num = ((struct syscall_metadata *)call->data)->syscall_nr;
647
648 mutex_lock(&syscall_trace_lock);
649 sys_perf_refcount_enter--;
650 clear_bit(num, enabled_perf_enter_syscalls);
651 if (!sys_perf_refcount_enter)
652 unregister_trace_sys_enter(perf_syscall_enter, NULL);
653 mutex_unlock(&syscall_trace_lock);
654}
655
656static int perf_call_bpf_exit(struct trace_event_call *call, struct pt_regs *regs,
657 struct syscall_trace_exit *rec)
658{
659 struct syscall_tp_t {
660 unsigned long long regs;
661 unsigned long syscall_nr;
662 unsigned long ret;
663 } param;
664
665 *(struct pt_regs **)¶m = regs;
666 param.syscall_nr = rec->nr;
667 param.ret = rec->ret;
668 return trace_call_bpf(call, ¶m);
669}
670
671static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
672{
673 struct syscall_metadata *sys_data;
674 struct syscall_trace_exit *rec;
675 struct hlist_head *head;
676 bool valid_prog_array;
677 int syscall_nr;
678 int rctx;
679 int size;
680
681 syscall_nr = trace_get_syscall_nr(current, regs);
682 if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
683 return;
684 if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
685 return;
686
687 sys_data = syscall_nr_to_meta(syscall_nr);
688 if (!sys_data)
689 return;
690
691 head = this_cpu_ptr(sys_data->exit_event->perf_events);
692 valid_prog_array = bpf_prog_array_valid(sys_data->exit_event);
693 if (!valid_prog_array && hlist_empty(head))
694 return;
695
696 /* We can probably do that at build time */
697 size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
698 size -= sizeof(u32);
699
700 rec = perf_trace_buf_alloc(size, NULL, &rctx);
701 if (!rec)
702 return;
703
704 rec->nr = syscall_nr;
705 rec->ret = syscall_get_return_value(current, regs);
706
707 if ((valid_prog_array &&
708 !perf_call_bpf_exit(sys_data->exit_event, regs, rec)) ||
709 hlist_empty(head)) {
710 perf_swevent_put_recursion_context(rctx);
711 return;
712 }
713
714 perf_trace_buf_submit(rec, size, rctx, sys_data->exit_event->event.type,
715 1, regs, head, NULL);
716}
717
718static int perf_sysexit_enable(struct trace_event_call *call)
719{
720 int ret = 0;
721 int num;
722
723 num = ((struct syscall_metadata *)call->data)->syscall_nr;
724
725 mutex_lock(&syscall_trace_lock);
726 if (!sys_perf_refcount_exit)
727 ret = register_trace_sys_exit(perf_syscall_exit, NULL);
728 if (ret) {
729 pr_info("event trace: Could not activate syscall exit trace point");
730 } else {
731 set_bit(num, enabled_perf_exit_syscalls);
732 sys_perf_refcount_exit++;
733 }
734 mutex_unlock(&syscall_trace_lock);
735 return ret;
736}
737
738static void perf_sysexit_disable(struct trace_event_call *call)
739{
740 int num;
741
742 num = ((struct syscall_metadata *)call->data)->syscall_nr;
743
744 mutex_lock(&syscall_trace_lock);
745 sys_perf_refcount_exit--;
746 clear_bit(num, enabled_perf_exit_syscalls);
747 if (!sys_perf_refcount_exit)
748 unregister_trace_sys_exit(perf_syscall_exit, NULL);
749 mutex_unlock(&syscall_trace_lock);
750}
751
752#endif /* CONFIG_PERF_EVENTS */
753
754static int syscall_enter_register(struct trace_event_call *event,
755 enum trace_reg type, void *data)
756{
757 struct trace_event_file *file = data;
758
759 switch (type) {
760 case TRACE_REG_REGISTER:
761 return reg_event_syscall_enter(file, event);
762 case TRACE_REG_UNREGISTER:
763 unreg_event_syscall_enter(file, event);
764 return 0;
765
766#ifdef CONFIG_PERF_EVENTS
767 case TRACE_REG_PERF_REGISTER:
768 return perf_sysenter_enable(event);
769 case TRACE_REG_PERF_UNREGISTER:
770 perf_sysenter_disable(event);
771 return 0;
772 case TRACE_REG_PERF_OPEN:
773 case TRACE_REG_PERF_CLOSE:
774 case TRACE_REG_PERF_ADD:
775 case TRACE_REG_PERF_DEL:
776 return 0;
777#endif
778 }
779 return 0;
780}
781
782static int syscall_exit_register(struct trace_event_call *event,
783 enum trace_reg type, void *data)
784{
785 struct trace_event_file *file = data;
786
787 switch (type) {
788 case TRACE_REG_REGISTER:
789 return reg_event_syscall_exit(file, event);
790 case TRACE_REG_UNREGISTER:
791 unreg_event_syscall_exit(file, event);
792 return 0;
793
794#ifdef CONFIG_PERF_EVENTS
795 case TRACE_REG_PERF_REGISTER:
796 return perf_sysexit_enable(event);
797 case TRACE_REG_PERF_UNREGISTER:
798 perf_sysexit_disable(event);
799 return 0;
800 case TRACE_REG_PERF_OPEN:
801 case TRACE_REG_PERF_CLOSE:
802 case TRACE_REG_PERF_ADD:
803 case TRACE_REG_PERF_DEL:
804 return 0;
805#endif
806 }
807 return 0;
808}
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
15static DEFINE_MUTEX(syscall_trace_lock);
16
17static int syscall_enter_register(struct trace_event_call *event,
18 enum trace_reg type, void *data);
19static int syscall_exit_register(struct trace_event_call *event,
20 enum trace_reg type, void *data);
21
22static struct list_head *
23syscall_get_enter_fields(struct trace_event_call *call)
24{
25 struct syscall_metadata *entry = call->data;
26
27 return &entry->enter_fields;
28}
29
30extern struct syscall_metadata *__start_syscalls_metadata[];
31extern struct syscall_metadata *__stop_syscalls_metadata[];
32
33static struct syscall_metadata **syscalls_metadata;
34
35#ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
36static 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 */
64static int
65trace_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
73static inline int
74trace_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
80static __init struct syscall_metadata *
81find_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
102static 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
110const 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
121static enum print_line_t
122print_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, ')');
162end:
163 trace_seq_putc(s, '\n');
164
165 return trace_handle_return(s);
166}
167
168static enum print_line_t
169print_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
199extern 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
207static 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
235static 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
260static 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
268static 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
292static 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
308static 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
358static 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
404static 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
425static 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
442static 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
463static 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
480static 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
505struct trace_event_functions enter_syscall_print_funcs = {
506 .trace = print_syscall_enter,
507};
508
509struct trace_event_functions exit_syscall_print_funcs = {
510 .trace = print_syscall_exit,
511};
512
513struct 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
521struct 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
529unsigned long __init __weak arch_syscall_addr(int nr)
530{
531 return (unsigned long)sys_call_table[nr];
532}
533
534void __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
560static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
561static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
562static int sys_perf_refcount_enter;
563static int sys_perf_refcount_exit;
564
565static 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 **)¶m = 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, ¶m);
581}
582
583static 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
634static 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
654static 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
668static 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 **)¶m = regs;
678 param.syscall_nr = rec->nr;
679 param.ret = rec->ret;
680 return trace_call_bpf(call, ¶m);
681}
682
683static 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
730static 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
750static 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
766static 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
794static 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}