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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 <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->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
204extern char *__bad_type_size(void);
205
206#define SYSCALL_FIELD(_type, _name) { \
207 .type = #_type, .name = #_name, \
208 .size = sizeof(_type), .align = __alignof__(_type), \
209 .is_signed = is_signed_type(_type), .filter_type = FILTER_OTHER }
210
211static int __init
212__set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
213{
214 int i;
215 int pos = 0;
216
217 /* When len=0, we just calculate the needed length */
218#define LEN_OR_ZERO (len ? len - pos : 0)
219
220 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
221 for (i = 0; i < entry->nb_args; i++) {
222 pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
223 entry->args[i], sizeof(unsigned long),
224 i == entry->nb_args - 1 ? "" : ", ");
225 }
226 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
227
228 for (i = 0; i < entry->nb_args; i++) {
229 pos += snprintf(buf + pos, LEN_OR_ZERO,
230 ", ((unsigned long)(REC->%s))", entry->args[i]);
231 }
232
233#undef LEN_OR_ZERO
234
235 /* return the length of print_fmt */
236 return pos;
237}
238
239static int __init set_syscall_print_fmt(struct trace_event_call *call)
240{
241 char *print_fmt;
242 int len;
243 struct syscall_metadata *entry = call->data;
244
245 if (entry->enter_event != call) {
246 call->print_fmt = "\"0x%lx\", REC->ret";
247 return 0;
248 }
249
250 /* First: called with 0 length to calculate the needed length */
251 len = __set_enter_print_fmt(entry, NULL, 0);
252
253 print_fmt = kmalloc(len + 1, GFP_KERNEL);
254 if (!print_fmt)
255 return -ENOMEM;
256
257 /* Second: actually write the @print_fmt */
258 __set_enter_print_fmt(entry, print_fmt, len + 1);
259 call->print_fmt = print_fmt;
260
261 return 0;
262}
263
264static void __init free_syscall_print_fmt(struct trace_event_call *call)
265{
266 struct syscall_metadata *entry = call->data;
267
268 if (entry->enter_event == call)
269 kfree(call->print_fmt);
270}
271
272static int __init syscall_enter_define_fields(struct trace_event_call *call)
273{
274 struct syscall_trace_enter trace;
275 struct syscall_metadata *meta = call->data;
276 int offset = offsetof(typeof(trace), args);
277 int ret = 0;
278 int i;
279
280 for (i = 0; i < meta->nb_args; i++) {
281 ret = trace_define_field(call, meta->types[i],
282 meta->args[i], offset,
283 sizeof(unsigned long), 0,
284 FILTER_OTHER);
285 if (ret)
286 break;
287 offset += sizeof(unsigned long);
288 }
289
290 return ret;
291}
292
293static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
294{
295 struct trace_array *tr = data;
296 struct trace_event_file *trace_file;
297 struct syscall_trace_enter *entry;
298 struct syscall_metadata *sys_data;
299 struct ring_buffer_event *event;
300 struct trace_buffer *buffer;
301 unsigned long irq_flags;
302 unsigned long args[6];
303 int pc;
304 int syscall_nr;
305 int size;
306
307 syscall_nr = trace_get_syscall_nr(current, regs);
308 if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
309 return;
310
311 /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE) */
312 trace_file = rcu_dereference_sched(tr->enter_syscall_files[syscall_nr]);
313 if (!trace_file)
314 return;
315
316 if (trace_trigger_soft_disabled(trace_file))
317 return;
318
319 sys_data = syscall_nr_to_meta(syscall_nr);
320 if (!sys_data)
321 return;
322
323 size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
324
325 local_save_flags(irq_flags);
326 pc = preempt_count();
327
328 buffer = tr->array_buffer.buffer;
329 event = trace_buffer_lock_reserve(buffer,
330 sys_data->enter_event->event.type, size, irq_flags, pc);
331 if (!event)
332 return;
333
334 entry = ring_buffer_event_data(event);
335 entry->nr = syscall_nr;
336 syscall_get_arguments(current, regs, args);
337 memcpy(entry->args, args, sizeof(unsigned long) * sys_data->nb_args);
338
339 event_trigger_unlock_commit(trace_file, buffer, event, entry,
340 irq_flags, pc);
341}
342
343static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
344{
345 struct trace_array *tr = data;
346 struct trace_event_file *trace_file;
347 struct syscall_trace_exit *entry;
348 struct syscall_metadata *sys_data;
349 struct ring_buffer_event *event;
350 struct trace_buffer *buffer;
351 unsigned long irq_flags;
352 int pc;
353 int syscall_nr;
354
355 syscall_nr = trace_get_syscall_nr(current, regs);
356 if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
357 return;
358
359 /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE()) */
360 trace_file = rcu_dereference_sched(tr->exit_syscall_files[syscall_nr]);
361 if (!trace_file)
362 return;
363
364 if (trace_trigger_soft_disabled(trace_file))
365 return;
366
367 sys_data = syscall_nr_to_meta(syscall_nr);
368 if (!sys_data)
369 return;
370
371 local_save_flags(irq_flags);
372 pc = preempt_count();
373
374 buffer = tr->array_buffer.buffer;
375 event = trace_buffer_lock_reserve(buffer,
376 sys_data->exit_event->event.type, sizeof(*entry),
377 irq_flags, pc);
378 if (!event)
379 return;
380
381 entry = ring_buffer_event_data(event);
382 entry->nr = syscall_nr;
383 entry->ret = syscall_get_return_value(current, regs);
384
385 event_trigger_unlock_commit(trace_file, buffer, event, entry,
386 irq_flags, pc);
387}
388
389static int reg_event_syscall_enter(struct trace_event_file *file,
390 struct trace_event_call *call)
391{
392 struct trace_array *tr = file->tr;
393 int ret = 0;
394 int num;
395
396 num = ((struct syscall_metadata *)call->data)->syscall_nr;
397 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
398 return -ENOSYS;
399 mutex_lock(&syscall_trace_lock);
400 if (!tr->sys_refcount_enter)
401 ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
402 if (!ret) {
403 rcu_assign_pointer(tr->enter_syscall_files[num], file);
404 tr->sys_refcount_enter++;
405 }
406 mutex_unlock(&syscall_trace_lock);
407 return ret;
408}
409
410static void unreg_event_syscall_enter(struct trace_event_file *file,
411 struct trace_event_call *call)
412{
413 struct trace_array *tr = file->tr;
414 int num;
415
416 num = ((struct syscall_metadata *)call->data)->syscall_nr;
417 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
418 return;
419 mutex_lock(&syscall_trace_lock);
420 tr->sys_refcount_enter--;
421 RCU_INIT_POINTER(tr->enter_syscall_files[num], NULL);
422 if (!tr->sys_refcount_enter)
423 unregister_trace_sys_enter(ftrace_syscall_enter, tr);
424 mutex_unlock(&syscall_trace_lock);
425}
426
427static int reg_event_syscall_exit(struct trace_event_file *file,
428 struct trace_event_call *call)
429{
430 struct trace_array *tr = file->tr;
431 int ret = 0;
432 int num;
433
434 num = ((struct syscall_metadata *)call->data)->syscall_nr;
435 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
436 return -ENOSYS;
437 mutex_lock(&syscall_trace_lock);
438 if (!tr->sys_refcount_exit)
439 ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
440 if (!ret) {
441 rcu_assign_pointer(tr->exit_syscall_files[num], file);
442 tr->sys_refcount_exit++;
443 }
444 mutex_unlock(&syscall_trace_lock);
445 return ret;
446}
447
448static void unreg_event_syscall_exit(struct trace_event_file *file,
449 struct trace_event_call *call)
450{
451 struct trace_array *tr = file->tr;
452 int num;
453
454 num = ((struct syscall_metadata *)call->data)->syscall_nr;
455 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
456 return;
457 mutex_lock(&syscall_trace_lock);
458 tr->sys_refcount_exit--;
459 RCU_INIT_POINTER(tr->exit_syscall_files[num], NULL);
460 if (!tr->sys_refcount_exit)
461 unregister_trace_sys_exit(ftrace_syscall_exit, tr);
462 mutex_unlock(&syscall_trace_lock);
463}
464
465static int __init init_syscall_trace(struct trace_event_call *call)
466{
467 int id;
468 int num;
469
470 num = ((struct syscall_metadata *)call->data)->syscall_nr;
471 if (num < 0 || num >= NR_syscalls) {
472 pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
473 ((struct syscall_metadata *)call->data)->name);
474 return -ENOSYS;
475 }
476
477 if (set_syscall_print_fmt(call) < 0)
478 return -ENOMEM;
479
480 id = trace_event_raw_init(call);
481
482 if (id < 0) {
483 free_syscall_print_fmt(call);
484 return id;
485 }
486
487 return id;
488}
489
490static struct trace_event_fields __refdata syscall_enter_fields_array[] = {
491 SYSCALL_FIELD(int, __syscall_nr),
492 { .type = TRACE_FUNCTION_TYPE,
493 .define_fields = syscall_enter_define_fields },
494 {}
495};
496
497struct trace_event_functions enter_syscall_print_funcs = {
498 .trace = print_syscall_enter,
499};
500
501struct trace_event_functions exit_syscall_print_funcs = {
502 .trace = print_syscall_exit,
503};
504
505struct trace_event_class __refdata event_class_syscall_enter = {
506 .system = "syscalls",
507 .reg = syscall_enter_register,
508 .fields_array = syscall_enter_fields_array,
509 .get_fields = syscall_get_enter_fields,
510 .raw_init = init_syscall_trace,
511};
512
513struct trace_event_class __refdata event_class_syscall_exit = {
514 .system = "syscalls",
515 .reg = syscall_exit_register,
516 .fields_array = (struct trace_event_fields[]){
517 SYSCALL_FIELD(int, __syscall_nr),
518 SYSCALL_FIELD(long, ret),
519 {}
520 },
521 .fields = LIST_HEAD_INIT(event_class_syscall_exit.fields),
522 .raw_init = init_syscall_trace,
523};
524
525unsigned long __init __weak arch_syscall_addr(int nr)
526{
527 return (unsigned long)sys_call_table[nr];
528}
529
530void __init init_ftrace_syscalls(void)
531{
532 struct syscall_metadata *meta;
533 unsigned long addr;
534 int i;
535 void *ret;
536
537 if (!IS_ENABLED(CONFIG_HAVE_SPARSE_SYSCALL_NR)) {
538 syscalls_metadata = kcalloc(NR_syscalls,
539 sizeof(*syscalls_metadata),
540 GFP_KERNEL);
541 if (!syscalls_metadata) {
542 WARN_ON(1);
543 return;
544 }
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
555 if (!IS_ENABLED(CONFIG_HAVE_SPARSE_SYSCALL_NR)) {
556 syscalls_metadata[i] = meta;
557 } else {
558 ret = xa_store(&syscalls_metadata_sparse, i, meta,
559 GFP_KERNEL);
560 WARN(xa_is_err(ret),
561 "Syscall memory allocation failed\n");
562 }
563
564 }
565}
566
567#ifdef CONFIG_PERF_EVENTS
568
569static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
570static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
571static int sys_perf_refcount_enter;
572static int sys_perf_refcount_exit;
573
574static int perf_call_bpf_enter(struct trace_event_call *call, struct pt_regs *regs,
575 struct syscall_metadata *sys_data,
576 struct syscall_trace_enter *rec)
577{
578 struct syscall_tp_t {
579 unsigned long long regs;
580 unsigned long syscall_nr;
581 unsigned long args[SYSCALL_DEFINE_MAXARGS];
582 } param;
583 int i;
584
585 *(struct pt_regs **)¶m = regs;
586 param.syscall_nr = rec->nr;
587 for (i = 0; i < sys_data->nb_args; i++)
588 param.args[i] = rec->args[i];
589 return trace_call_bpf(call, ¶m);
590}
591
592static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
593{
594 struct syscall_metadata *sys_data;
595 struct syscall_trace_enter *rec;
596 struct hlist_head *head;
597 unsigned long args[6];
598 bool valid_prog_array;
599 int syscall_nr;
600 int rctx;
601 int size;
602
603 syscall_nr = trace_get_syscall_nr(current, regs);
604 if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
605 return;
606 if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
607 return;
608
609 sys_data = syscall_nr_to_meta(syscall_nr);
610 if (!sys_data)
611 return;
612
613 head = this_cpu_ptr(sys_data->enter_event->perf_events);
614 valid_prog_array = bpf_prog_array_valid(sys_data->enter_event);
615 if (!valid_prog_array && hlist_empty(head))
616 return;
617
618 /* get the size after alignment with the u32 buffer size field */
619 size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
620 size = ALIGN(size + sizeof(u32), sizeof(u64));
621 size -= sizeof(u32);
622
623 rec = perf_trace_buf_alloc(size, NULL, &rctx);
624 if (!rec)
625 return;
626
627 rec->nr = syscall_nr;
628 syscall_get_arguments(current, regs, args);
629 memcpy(&rec->args, args, sizeof(unsigned long) * sys_data->nb_args);
630
631 if ((valid_prog_array &&
632 !perf_call_bpf_enter(sys_data->enter_event, regs, sys_data, rec)) ||
633 hlist_empty(head)) {
634 perf_swevent_put_recursion_context(rctx);
635 return;
636 }
637
638 perf_trace_buf_submit(rec, size, rctx,
639 sys_data->enter_event->event.type, 1, regs,
640 head, NULL);
641}
642
643static int perf_sysenter_enable(struct trace_event_call *call)
644{
645 int ret = 0;
646 int num;
647
648 num = ((struct syscall_metadata *)call->data)->syscall_nr;
649
650 mutex_lock(&syscall_trace_lock);
651 if (!sys_perf_refcount_enter)
652 ret = register_trace_sys_enter(perf_syscall_enter, NULL);
653 if (ret) {
654 pr_info("event trace: Could not activate syscall entry trace point");
655 } else {
656 set_bit(num, enabled_perf_enter_syscalls);
657 sys_perf_refcount_enter++;
658 }
659 mutex_unlock(&syscall_trace_lock);
660 return ret;
661}
662
663static void perf_sysenter_disable(struct trace_event_call *call)
664{
665 int num;
666
667 num = ((struct syscall_metadata *)call->data)->syscall_nr;
668
669 mutex_lock(&syscall_trace_lock);
670 sys_perf_refcount_enter--;
671 clear_bit(num, enabled_perf_enter_syscalls);
672 if (!sys_perf_refcount_enter)
673 unregister_trace_sys_enter(perf_syscall_enter, NULL);
674 mutex_unlock(&syscall_trace_lock);
675}
676
677static int perf_call_bpf_exit(struct trace_event_call *call, struct pt_regs *regs,
678 struct syscall_trace_exit *rec)
679{
680 struct syscall_tp_t {
681 unsigned long long regs;
682 unsigned long syscall_nr;
683 unsigned long ret;
684 } param;
685
686 *(struct pt_regs **)¶m = regs;
687 param.syscall_nr = rec->nr;
688 param.ret = rec->ret;
689 return trace_call_bpf(call, ¶m);
690}
691
692static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
693{
694 struct syscall_metadata *sys_data;
695 struct syscall_trace_exit *rec;
696 struct hlist_head *head;
697 bool valid_prog_array;
698 int syscall_nr;
699 int rctx;
700 int size;
701
702 syscall_nr = trace_get_syscall_nr(current, regs);
703 if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
704 return;
705 if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
706 return;
707
708 sys_data = syscall_nr_to_meta(syscall_nr);
709 if (!sys_data)
710 return;
711
712 head = this_cpu_ptr(sys_data->exit_event->perf_events);
713 valid_prog_array = bpf_prog_array_valid(sys_data->exit_event);
714 if (!valid_prog_array && hlist_empty(head))
715 return;
716
717 /* We can probably do that at build time */
718 size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
719 size -= sizeof(u32);
720
721 rec = perf_trace_buf_alloc(size, NULL, &rctx);
722 if (!rec)
723 return;
724
725 rec->nr = syscall_nr;
726 rec->ret = syscall_get_return_value(current, regs);
727
728 if ((valid_prog_array &&
729 !perf_call_bpf_exit(sys_data->exit_event, regs, rec)) ||
730 hlist_empty(head)) {
731 perf_swevent_put_recursion_context(rctx);
732 return;
733 }
734
735 perf_trace_buf_submit(rec, size, rctx, sys_data->exit_event->event.type,
736 1, regs, head, NULL);
737}
738
739static int perf_sysexit_enable(struct trace_event_call *call)
740{
741 int ret = 0;
742 int num;
743
744 num = ((struct syscall_metadata *)call->data)->syscall_nr;
745
746 mutex_lock(&syscall_trace_lock);
747 if (!sys_perf_refcount_exit)
748 ret = register_trace_sys_exit(perf_syscall_exit, NULL);
749 if (ret) {
750 pr_info("event trace: Could not activate syscall exit trace point");
751 } else {
752 set_bit(num, enabled_perf_exit_syscalls);
753 sys_perf_refcount_exit++;
754 }
755 mutex_unlock(&syscall_trace_lock);
756 return ret;
757}
758
759static void perf_sysexit_disable(struct trace_event_call *call)
760{
761 int num;
762
763 num = ((struct syscall_metadata *)call->data)->syscall_nr;
764
765 mutex_lock(&syscall_trace_lock);
766 sys_perf_refcount_exit--;
767 clear_bit(num, enabled_perf_exit_syscalls);
768 if (!sys_perf_refcount_exit)
769 unregister_trace_sys_exit(perf_syscall_exit, NULL);
770 mutex_unlock(&syscall_trace_lock);
771}
772
773#endif /* CONFIG_PERF_EVENTS */
774
775static int syscall_enter_register(struct trace_event_call *event,
776 enum trace_reg type, void *data)
777{
778 struct trace_event_file *file = data;
779
780 switch (type) {
781 case TRACE_REG_REGISTER:
782 return reg_event_syscall_enter(file, event);
783 case TRACE_REG_UNREGISTER:
784 unreg_event_syscall_enter(file, event);
785 return 0;
786
787#ifdef CONFIG_PERF_EVENTS
788 case TRACE_REG_PERF_REGISTER:
789 return perf_sysenter_enable(event);
790 case TRACE_REG_PERF_UNREGISTER:
791 perf_sysenter_disable(event);
792 return 0;
793 case TRACE_REG_PERF_OPEN:
794 case TRACE_REG_PERF_CLOSE:
795 case TRACE_REG_PERF_ADD:
796 case TRACE_REG_PERF_DEL:
797 return 0;
798#endif
799 }
800 return 0;
801}
802
803static int syscall_exit_register(struct trace_event_call *event,
804 enum trace_reg type, void *data)
805{
806 struct trace_event_file *file = data;
807
808 switch (type) {
809 case TRACE_REG_REGISTER:
810 return reg_event_syscall_exit(file, event);
811 case TRACE_REG_UNREGISTER:
812 unreg_event_syscall_exit(file, event);
813 return 0;
814
815#ifdef CONFIG_PERF_EVENTS
816 case TRACE_REG_PERF_REGISTER:
817 return perf_sysexit_enable(event);
818 case TRACE_REG_PERF_UNREGISTER:
819 perf_sysexit_disable(event);
820 return 0;
821 case TRACE_REG_PERF_OPEN:
822 case TRACE_REG_PERF_CLOSE:
823 case TRACE_REG_PERF_ADD:
824 case TRACE_REG_PERF_DEL:
825 return 0;
826#endif
827 }
828 return 0;
829}