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1#include <trace/syscall.h>
2#include <trace/events/syscalls.h>
3#include <linux/syscalls.h>
4#include <linux/slab.h>
5#include <linux/kernel.h>
6#include <linux/module.h> /* for MODULE_NAME_LEN via KSYM_SYMBOL_LEN */
7#include <linux/ftrace.h>
8#include <linux/perf_event.h>
9#include <asm/syscall.h>
10
11#include "trace_output.h"
12#include "trace.h"
13
14static DEFINE_MUTEX(syscall_trace_lock);
15
16static int syscall_enter_register(struct ftrace_event_call *event,
17 enum trace_reg type, void *data);
18static int syscall_exit_register(struct ftrace_event_call *event,
19 enum trace_reg type, void *data);
20
21static struct list_head *
22syscall_get_enter_fields(struct ftrace_event_call *call)
23{
24 struct syscall_metadata *entry = call->data;
25
26 return &entry->enter_fields;
27}
28
29extern struct syscall_metadata *__start_syscalls_metadata[];
30extern struct syscall_metadata *__stop_syscalls_metadata[];
31
32static struct syscall_metadata **syscalls_metadata;
33
34#ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
35static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
36{
37 /*
38 * Only compare after the "sys" prefix. Archs that use
39 * syscall wrappers may have syscalls symbols aliases prefixed
40 * with ".SyS" or ".sys" instead of "sys", leading to an unwanted
41 * mismatch.
42 */
43 return !strcmp(sym + 3, name + 3);
44}
45#endif
46
47#ifdef ARCH_TRACE_IGNORE_COMPAT_SYSCALLS
48/*
49 * Some architectures that allow for 32bit applications
50 * to run on a 64bit kernel, do not map the syscalls for
51 * the 32bit tasks the same as they do for 64bit tasks.
52 *
53 * *cough*x86*cough*
54 *
55 * In such a case, instead of reporting the wrong syscalls,
56 * simply ignore them.
57 *
58 * For an arch to ignore the compat syscalls it needs to
59 * define ARCH_TRACE_IGNORE_COMPAT_SYSCALLS as well as
60 * define the function arch_trace_is_compat_syscall() to let
61 * the tracing system know that it should ignore it.
62 */
63static int
64trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs)
65{
66 if (unlikely(arch_trace_is_compat_syscall(regs)))
67 return -1;
68
69 return syscall_get_nr(task, regs);
70}
71#else
72static inline int
73trace_get_syscall_nr(struct task_struct *task, struct pt_regs *regs)
74{
75 return syscall_get_nr(task, regs);
76}
77#endif /* ARCH_TRACE_IGNORE_COMPAT_SYSCALLS */
78
79static __init struct syscall_metadata *
80find_syscall_meta(unsigned long syscall)
81{
82 struct syscall_metadata **start;
83 struct syscall_metadata **stop;
84 char str[KSYM_SYMBOL_LEN];
85
86
87 start = __start_syscalls_metadata;
88 stop = __stop_syscalls_metadata;
89 kallsyms_lookup(syscall, NULL, NULL, NULL, str);
90
91 if (arch_syscall_match_sym_name(str, "sys_ni_syscall"))
92 return NULL;
93
94 for ( ; start < stop; start++) {
95 if ((*start)->name && arch_syscall_match_sym_name(str, (*start)->name))
96 return *start;
97 }
98 return NULL;
99}
100
101static struct syscall_metadata *syscall_nr_to_meta(int nr)
102{
103 if (!syscalls_metadata || nr >= NR_syscalls || nr < 0)
104 return NULL;
105
106 return syscalls_metadata[nr];
107}
108
109static enum print_line_t
110print_syscall_enter(struct trace_iterator *iter, int flags,
111 struct trace_event *event)
112{
113 struct trace_seq *s = &iter->seq;
114 struct trace_entry *ent = iter->ent;
115 struct syscall_trace_enter *trace;
116 struct syscall_metadata *entry;
117 int i, ret, syscall;
118
119 trace = (typeof(trace))ent;
120 syscall = trace->nr;
121 entry = syscall_nr_to_meta(syscall);
122
123 if (!entry)
124 goto end;
125
126 if (entry->enter_event->event.type != ent->type) {
127 WARN_ON_ONCE(1);
128 goto end;
129 }
130
131 ret = trace_seq_printf(s, "%s(", entry->name);
132 if (!ret)
133 return TRACE_TYPE_PARTIAL_LINE;
134
135 for (i = 0; i < entry->nb_args; i++) {
136 /* parameter types */
137 if (trace_flags & TRACE_ITER_VERBOSE) {
138 ret = trace_seq_printf(s, "%s ", entry->types[i]);
139 if (!ret)
140 return TRACE_TYPE_PARTIAL_LINE;
141 }
142 /* parameter values */
143 ret = trace_seq_printf(s, "%s: %lx%s", entry->args[i],
144 trace->args[i],
145 i == entry->nb_args - 1 ? "" : ", ");
146 if (!ret)
147 return TRACE_TYPE_PARTIAL_LINE;
148 }
149
150 ret = trace_seq_putc(s, ')');
151 if (!ret)
152 return TRACE_TYPE_PARTIAL_LINE;
153
154end:
155 ret = trace_seq_putc(s, '\n');
156 if (!ret)
157 return TRACE_TYPE_PARTIAL_LINE;
158
159 return TRACE_TYPE_HANDLED;
160}
161
162static enum print_line_t
163print_syscall_exit(struct trace_iterator *iter, int flags,
164 struct trace_event *event)
165{
166 struct trace_seq *s = &iter->seq;
167 struct trace_entry *ent = iter->ent;
168 struct syscall_trace_exit *trace;
169 int syscall;
170 struct syscall_metadata *entry;
171 int ret;
172
173 trace = (typeof(trace))ent;
174 syscall = trace->nr;
175 entry = syscall_nr_to_meta(syscall);
176
177 if (!entry) {
178 trace_seq_putc(s, '\n');
179 return TRACE_TYPE_HANDLED;
180 }
181
182 if (entry->exit_event->event.type != ent->type) {
183 WARN_ON_ONCE(1);
184 return TRACE_TYPE_UNHANDLED;
185 }
186
187 ret = trace_seq_printf(s, "%s -> 0x%lx\n", entry->name,
188 trace->ret);
189 if (!ret)
190 return TRACE_TYPE_PARTIAL_LINE;
191
192 return TRACE_TYPE_HANDLED;
193}
194
195extern char *__bad_type_size(void);
196
197#define SYSCALL_FIELD(type, name) \
198 sizeof(type) != sizeof(trace.name) ? \
199 __bad_type_size() : \
200 #type, #name, offsetof(typeof(trace), name), \
201 sizeof(trace.name), is_signed_type(type)
202
203static int __init
204__set_enter_print_fmt(struct syscall_metadata *entry, char *buf, int len)
205{
206 int i;
207 int pos = 0;
208
209 /* When len=0, we just calculate the needed length */
210#define LEN_OR_ZERO (len ? len - pos : 0)
211
212 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
213 for (i = 0; i < entry->nb_args; i++) {
214 pos += snprintf(buf + pos, LEN_OR_ZERO, "%s: 0x%%0%zulx%s",
215 entry->args[i], sizeof(unsigned long),
216 i == entry->nb_args - 1 ? "" : ", ");
217 }
218 pos += snprintf(buf + pos, LEN_OR_ZERO, "\"");
219
220 for (i = 0; i < entry->nb_args; i++) {
221 pos += snprintf(buf + pos, LEN_OR_ZERO,
222 ", ((unsigned long)(REC->%s))", entry->args[i]);
223 }
224
225#undef LEN_OR_ZERO
226
227 /* return the length of print_fmt */
228 return pos;
229}
230
231static int __init set_syscall_print_fmt(struct ftrace_event_call *call)
232{
233 char *print_fmt;
234 int len;
235 struct syscall_metadata *entry = call->data;
236
237 if (entry->enter_event != call) {
238 call->print_fmt = "\"0x%lx\", REC->ret";
239 return 0;
240 }
241
242 /* First: called with 0 length to calculate the needed length */
243 len = __set_enter_print_fmt(entry, NULL, 0);
244
245 print_fmt = kmalloc(len + 1, GFP_KERNEL);
246 if (!print_fmt)
247 return -ENOMEM;
248
249 /* Second: actually write the @print_fmt */
250 __set_enter_print_fmt(entry, print_fmt, len + 1);
251 call->print_fmt = print_fmt;
252
253 return 0;
254}
255
256static void __init free_syscall_print_fmt(struct ftrace_event_call *call)
257{
258 struct syscall_metadata *entry = call->data;
259
260 if (entry->enter_event == call)
261 kfree(call->print_fmt);
262}
263
264static int __init syscall_enter_define_fields(struct ftrace_event_call *call)
265{
266 struct syscall_trace_enter trace;
267 struct syscall_metadata *meta = call->data;
268 int ret;
269 int i;
270 int offset = offsetof(typeof(trace), args);
271
272 ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
273 if (ret)
274 return ret;
275
276 for (i = 0; i < meta->nb_args; i++) {
277 ret = trace_define_field(call, meta->types[i],
278 meta->args[i], offset,
279 sizeof(unsigned long), 0,
280 FILTER_OTHER);
281 offset += sizeof(unsigned long);
282 }
283
284 return ret;
285}
286
287static int __init syscall_exit_define_fields(struct ftrace_event_call *call)
288{
289 struct syscall_trace_exit trace;
290 int ret;
291
292 ret = trace_define_field(call, SYSCALL_FIELD(int, nr), FILTER_OTHER);
293 if (ret)
294 return ret;
295
296 ret = trace_define_field(call, SYSCALL_FIELD(long, ret),
297 FILTER_OTHER);
298
299 return ret;
300}
301
302static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
303{
304 struct trace_array *tr = data;
305 struct ftrace_event_file *ftrace_file;
306 struct syscall_trace_enter *entry;
307 struct syscall_metadata *sys_data;
308 struct ring_buffer_event *event;
309 struct ring_buffer *buffer;
310 unsigned long irq_flags;
311 int pc;
312 int syscall_nr;
313 int size;
314
315 syscall_nr = trace_get_syscall_nr(current, regs);
316 if (syscall_nr < 0)
317 return;
318
319 /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE) */
320 ftrace_file = rcu_dereference_sched(tr->enter_syscall_files[syscall_nr]);
321 if (!ftrace_file)
322 return;
323
324 if (ftrace_trigger_soft_disabled(ftrace_file))
325 return;
326
327 sys_data = syscall_nr_to_meta(syscall_nr);
328 if (!sys_data)
329 return;
330
331 size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
332
333 local_save_flags(irq_flags);
334 pc = preempt_count();
335
336 buffer = tr->trace_buffer.buffer;
337 event = trace_buffer_lock_reserve(buffer,
338 sys_data->enter_event->event.type, size, irq_flags, pc);
339 if (!event)
340 return;
341
342 entry = ring_buffer_event_data(event);
343 entry->nr = syscall_nr;
344 syscall_get_arguments(current, regs, 0, sys_data->nb_args, entry->args);
345
346 event_trigger_unlock_commit(ftrace_file, buffer, event, entry,
347 irq_flags, pc);
348}
349
350static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
351{
352 struct trace_array *tr = data;
353 struct ftrace_event_file *ftrace_file;
354 struct syscall_trace_exit *entry;
355 struct syscall_metadata *sys_data;
356 struct ring_buffer_event *event;
357 struct ring_buffer *buffer;
358 unsigned long irq_flags;
359 int pc;
360 int syscall_nr;
361
362 syscall_nr = trace_get_syscall_nr(current, regs);
363 if (syscall_nr < 0)
364 return;
365
366 /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE()) */
367 ftrace_file = rcu_dereference_sched(tr->exit_syscall_files[syscall_nr]);
368 if (!ftrace_file)
369 return;
370
371 if (ftrace_trigger_soft_disabled(ftrace_file))
372 return;
373
374 sys_data = syscall_nr_to_meta(syscall_nr);
375 if (!sys_data)
376 return;
377
378 local_save_flags(irq_flags);
379 pc = preempt_count();
380
381 buffer = tr->trace_buffer.buffer;
382 event = trace_buffer_lock_reserve(buffer,
383 sys_data->exit_event->event.type, sizeof(*entry),
384 irq_flags, pc);
385 if (!event)
386 return;
387
388 entry = ring_buffer_event_data(event);
389 entry->nr = syscall_nr;
390 entry->ret = syscall_get_return_value(current, regs);
391
392 event_trigger_unlock_commit(ftrace_file, buffer, event, entry,
393 irq_flags, pc);
394}
395
396static int reg_event_syscall_enter(struct ftrace_event_file *file,
397 struct ftrace_event_call *call)
398{
399 struct trace_array *tr = file->tr;
400 int ret = 0;
401 int num;
402
403 num = ((struct syscall_metadata *)call->data)->syscall_nr;
404 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
405 return -ENOSYS;
406 mutex_lock(&syscall_trace_lock);
407 if (!tr->sys_refcount_enter)
408 ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
409 if (!ret) {
410 rcu_assign_pointer(tr->enter_syscall_files[num], file);
411 tr->sys_refcount_enter++;
412 }
413 mutex_unlock(&syscall_trace_lock);
414 return ret;
415}
416
417static void unreg_event_syscall_enter(struct ftrace_event_file *file,
418 struct ftrace_event_call *call)
419{
420 struct trace_array *tr = file->tr;
421 int num;
422
423 num = ((struct syscall_metadata *)call->data)->syscall_nr;
424 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
425 return;
426 mutex_lock(&syscall_trace_lock);
427 tr->sys_refcount_enter--;
428 rcu_assign_pointer(tr->enter_syscall_files[num], NULL);
429 if (!tr->sys_refcount_enter)
430 unregister_trace_sys_enter(ftrace_syscall_enter, tr);
431 mutex_unlock(&syscall_trace_lock);
432}
433
434static int reg_event_syscall_exit(struct ftrace_event_file *file,
435 struct ftrace_event_call *call)
436{
437 struct trace_array *tr = file->tr;
438 int ret = 0;
439 int num;
440
441 num = ((struct syscall_metadata *)call->data)->syscall_nr;
442 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
443 return -ENOSYS;
444 mutex_lock(&syscall_trace_lock);
445 if (!tr->sys_refcount_exit)
446 ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
447 if (!ret) {
448 rcu_assign_pointer(tr->exit_syscall_files[num], file);
449 tr->sys_refcount_exit++;
450 }
451 mutex_unlock(&syscall_trace_lock);
452 return ret;
453}
454
455static void unreg_event_syscall_exit(struct ftrace_event_file *file,
456 struct ftrace_event_call *call)
457{
458 struct trace_array *tr = file->tr;
459 int num;
460
461 num = ((struct syscall_metadata *)call->data)->syscall_nr;
462 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
463 return;
464 mutex_lock(&syscall_trace_lock);
465 tr->sys_refcount_exit--;
466 rcu_assign_pointer(tr->exit_syscall_files[num], NULL);
467 if (!tr->sys_refcount_exit)
468 unregister_trace_sys_exit(ftrace_syscall_exit, tr);
469 mutex_unlock(&syscall_trace_lock);
470}
471
472static int __init init_syscall_trace(struct ftrace_event_call *call)
473{
474 int id;
475 int num;
476
477 num = ((struct syscall_metadata *)call->data)->syscall_nr;
478 if (num < 0 || num >= NR_syscalls) {
479 pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
480 ((struct syscall_metadata *)call->data)->name);
481 return -ENOSYS;
482 }
483
484 if (set_syscall_print_fmt(call) < 0)
485 return -ENOMEM;
486
487 id = trace_event_raw_init(call);
488
489 if (id < 0) {
490 free_syscall_print_fmt(call);
491 return id;
492 }
493
494 return id;
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 ftrace_event_class __refdata event_class_syscall_enter = {
506 .system = "syscalls",
507 .reg = syscall_enter_register,
508 .define_fields = syscall_enter_define_fields,
509 .get_fields = syscall_get_enter_fields,
510 .raw_init = init_syscall_trace,
511};
512
513struct ftrace_event_class __refdata event_class_syscall_exit = {
514 .system = "syscalls",
515 .reg = syscall_exit_register,
516 .define_fields = syscall_exit_define_fields,
517 .fields = LIST_HEAD_INIT(event_class_syscall_exit.fields),
518 .raw_init = init_syscall_trace,
519};
520
521unsigned long __init __weak arch_syscall_addr(int nr)
522{
523 return (unsigned long)sys_call_table[nr];
524}
525
526static int __init init_ftrace_syscalls(void)
527{
528 struct syscall_metadata *meta;
529 unsigned long addr;
530 int i;
531
532 syscalls_metadata = kcalloc(NR_syscalls, sizeof(*syscalls_metadata),
533 GFP_KERNEL);
534 if (!syscalls_metadata) {
535 WARN_ON(1);
536 return -ENOMEM;
537 }
538
539 for (i = 0; i < NR_syscalls; i++) {
540 addr = arch_syscall_addr(i);
541 meta = find_syscall_meta(addr);
542 if (!meta)
543 continue;
544
545 meta->syscall_nr = i;
546 syscalls_metadata[i] = meta;
547 }
548
549 return 0;
550}
551early_initcall(init_ftrace_syscalls);
552
553#ifdef CONFIG_PERF_EVENTS
554
555static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
556static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
557static int sys_perf_refcount_enter;
558static int sys_perf_refcount_exit;
559
560static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
561{
562 struct syscall_metadata *sys_data;
563 struct syscall_trace_enter *rec;
564 struct hlist_head *head;
565 int syscall_nr;
566 int rctx;
567 int size;
568
569 syscall_nr = trace_get_syscall_nr(current, regs);
570 if (syscall_nr < 0)
571 return;
572 if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
573 return;
574
575 sys_data = syscall_nr_to_meta(syscall_nr);
576 if (!sys_data)
577 return;
578
579 head = this_cpu_ptr(sys_data->enter_event->perf_events);
580 if (hlist_empty(head))
581 return;
582
583 /* get the size after alignment with the u32 buffer size field */
584 size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
585 size = ALIGN(size + sizeof(u32), sizeof(u64));
586 size -= sizeof(u32);
587
588 rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size,
589 sys_data->enter_event->event.type, regs, &rctx);
590 if (!rec)
591 return;
592
593 rec->nr = syscall_nr;
594 syscall_get_arguments(current, regs, 0, sys_data->nb_args,
595 (unsigned long *)&rec->args);
596 perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
597}
598
599static int perf_sysenter_enable(struct ftrace_event_call *call)
600{
601 int ret = 0;
602 int num;
603
604 num = ((struct syscall_metadata *)call->data)->syscall_nr;
605
606 mutex_lock(&syscall_trace_lock);
607 if (!sys_perf_refcount_enter)
608 ret = register_trace_sys_enter(perf_syscall_enter, NULL);
609 if (ret) {
610 pr_info("event trace: Could not activate"
611 "syscall entry trace point");
612 } else {
613 set_bit(num, enabled_perf_enter_syscalls);
614 sys_perf_refcount_enter++;
615 }
616 mutex_unlock(&syscall_trace_lock);
617 return ret;
618}
619
620static void perf_sysenter_disable(struct ftrace_event_call *call)
621{
622 int num;
623
624 num = ((struct syscall_metadata *)call->data)->syscall_nr;
625
626 mutex_lock(&syscall_trace_lock);
627 sys_perf_refcount_enter--;
628 clear_bit(num, enabled_perf_enter_syscalls);
629 if (!sys_perf_refcount_enter)
630 unregister_trace_sys_enter(perf_syscall_enter, NULL);
631 mutex_unlock(&syscall_trace_lock);
632}
633
634static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
635{
636 struct syscall_metadata *sys_data;
637 struct syscall_trace_exit *rec;
638 struct hlist_head *head;
639 int syscall_nr;
640 int rctx;
641 int size;
642
643 syscall_nr = trace_get_syscall_nr(current, regs);
644 if (syscall_nr < 0)
645 return;
646 if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
647 return;
648
649 sys_data = syscall_nr_to_meta(syscall_nr);
650 if (!sys_data)
651 return;
652
653 head = this_cpu_ptr(sys_data->exit_event->perf_events);
654 if (hlist_empty(head))
655 return;
656
657 /* We can probably do that at build time */
658 size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
659 size -= sizeof(u32);
660
661 rec = (struct syscall_trace_exit *)perf_trace_buf_prepare(size,
662 sys_data->exit_event->event.type, regs, &rctx);
663 if (!rec)
664 return;
665
666 rec->nr = syscall_nr;
667 rec->ret = syscall_get_return_value(current, regs);
668 perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head, NULL);
669}
670
671static int perf_sysexit_enable(struct ftrace_event_call *call)
672{
673 int ret = 0;
674 int num;
675
676 num = ((struct syscall_metadata *)call->data)->syscall_nr;
677
678 mutex_lock(&syscall_trace_lock);
679 if (!sys_perf_refcount_exit)
680 ret = register_trace_sys_exit(perf_syscall_exit, NULL);
681 if (ret) {
682 pr_info("event trace: Could not activate"
683 "syscall exit trace point");
684 } else {
685 set_bit(num, enabled_perf_exit_syscalls);
686 sys_perf_refcount_exit++;
687 }
688 mutex_unlock(&syscall_trace_lock);
689 return ret;
690}
691
692static void perf_sysexit_disable(struct ftrace_event_call *call)
693{
694 int num;
695
696 num = ((struct syscall_metadata *)call->data)->syscall_nr;
697
698 mutex_lock(&syscall_trace_lock);
699 sys_perf_refcount_exit--;
700 clear_bit(num, enabled_perf_exit_syscalls);
701 if (!sys_perf_refcount_exit)
702 unregister_trace_sys_exit(perf_syscall_exit, NULL);
703 mutex_unlock(&syscall_trace_lock);
704}
705
706#endif /* CONFIG_PERF_EVENTS */
707
708static int syscall_enter_register(struct ftrace_event_call *event,
709 enum trace_reg type, void *data)
710{
711 struct ftrace_event_file *file = data;
712
713 switch (type) {
714 case TRACE_REG_REGISTER:
715 return reg_event_syscall_enter(file, event);
716 case TRACE_REG_UNREGISTER:
717 unreg_event_syscall_enter(file, event);
718 return 0;
719
720#ifdef CONFIG_PERF_EVENTS
721 case TRACE_REG_PERF_REGISTER:
722 return perf_sysenter_enable(event);
723 case TRACE_REG_PERF_UNREGISTER:
724 perf_sysenter_disable(event);
725 return 0;
726 case TRACE_REG_PERF_OPEN:
727 case TRACE_REG_PERF_CLOSE:
728 case TRACE_REG_PERF_ADD:
729 case TRACE_REG_PERF_DEL:
730 return 0;
731#endif
732 }
733 return 0;
734}
735
736static int syscall_exit_register(struct ftrace_event_call *event,
737 enum trace_reg type, void *data)
738{
739 struct ftrace_event_file *file = data;
740
741 switch (type) {
742 case TRACE_REG_REGISTER:
743 return reg_event_syscall_exit(file, event);
744 case TRACE_REG_UNREGISTER:
745 unreg_event_syscall_exit(file, event);
746 return 0;
747
748#ifdef CONFIG_PERF_EVENTS
749 case TRACE_REG_PERF_REGISTER:
750 return perf_sysexit_enable(event);
751 case TRACE_REG_PERF_UNREGISTER:
752 perf_sysexit_disable(event);
753 return 0;
754 case TRACE_REG_PERF_OPEN:
755 case TRACE_REG_PERF_CLOSE:
756 case TRACE_REG_PERF_ADD:
757 case TRACE_REG_PERF_DEL:
758 return 0;
759#endif
760 }
761 return 0;
762}
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 /*
303 * Syscall probe called with preemption enabled, but the ring
304 * buffer and per-cpu data require preemption to be disabled.
305 */
306 might_fault();
307 guard(preempt_notrace)();
308
309 syscall_nr = trace_get_syscall_nr(current, regs);
310 if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
311 return;
312
313 /* Here we're inside tp handler's rcu_read_lock_sched (__DO_TRACE) */
314 trace_file = rcu_dereference_sched(tr->enter_syscall_files[syscall_nr]);
315 if (!trace_file)
316 return;
317
318 if (trace_trigger_soft_disabled(trace_file))
319 return;
320
321 sys_data = syscall_nr_to_meta(syscall_nr);
322 if (!sys_data)
323 return;
324
325 size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;
326
327 entry = trace_event_buffer_reserve(&fbuffer, trace_file, size);
328 if (!entry)
329 return;
330
331 entry = ring_buffer_event_data(fbuffer.event);
332 entry->nr = syscall_nr;
333 syscall_get_arguments(current, regs, args);
334 memcpy(entry->args, args, sizeof(unsigned long) * sys_data->nb_args);
335
336 trace_event_buffer_commit(&fbuffer);
337}
338
339static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
340{
341 struct trace_array *tr = data;
342 struct trace_event_file *trace_file;
343 struct syscall_trace_exit *entry;
344 struct syscall_metadata *sys_data;
345 struct trace_event_buffer fbuffer;
346 int syscall_nr;
347
348 /*
349 * Syscall probe called with preemption enabled, but the ring
350 * buffer and per-cpu data require preemption to be disabled.
351 */
352 might_fault();
353 guard(preempt_notrace)();
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 entry = trace_event_buffer_reserve(&fbuffer, trace_file, sizeof(*entry));
372 if (!entry)
373 return;
374
375 entry = ring_buffer_event_data(fbuffer.event);
376 entry->nr = syscall_nr;
377 entry->ret = syscall_get_return_value(current, regs);
378
379 trace_event_buffer_commit(&fbuffer);
380}
381
382static int reg_event_syscall_enter(struct trace_event_file *file,
383 struct trace_event_call *call)
384{
385 struct trace_array *tr = file->tr;
386 int ret = 0;
387 int num;
388
389 num = ((struct syscall_metadata *)call->data)->syscall_nr;
390 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
391 return -ENOSYS;
392 mutex_lock(&syscall_trace_lock);
393 if (!tr->sys_refcount_enter)
394 ret = register_trace_sys_enter(ftrace_syscall_enter, tr);
395 if (!ret) {
396 rcu_assign_pointer(tr->enter_syscall_files[num], file);
397 tr->sys_refcount_enter++;
398 }
399 mutex_unlock(&syscall_trace_lock);
400 return ret;
401}
402
403static void unreg_event_syscall_enter(struct trace_event_file *file,
404 struct trace_event_call *call)
405{
406 struct trace_array *tr = file->tr;
407 int num;
408
409 num = ((struct syscall_metadata *)call->data)->syscall_nr;
410 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
411 return;
412 mutex_lock(&syscall_trace_lock);
413 tr->sys_refcount_enter--;
414 RCU_INIT_POINTER(tr->enter_syscall_files[num], NULL);
415 if (!tr->sys_refcount_enter)
416 unregister_trace_sys_enter(ftrace_syscall_enter, tr);
417 mutex_unlock(&syscall_trace_lock);
418}
419
420static int reg_event_syscall_exit(struct trace_event_file *file,
421 struct trace_event_call *call)
422{
423 struct trace_array *tr = file->tr;
424 int ret = 0;
425 int num;
426
427 num = ((struct syscall_metadata *)call->data)->syscall_nr;
428 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
429 return -ENOSYS;
430 mutex_lock(&syscall_trace_lock);
431 if (!tr->sys_refcount_exit)
432 ret = register_trace_sys_exit(ftrace_syscall_exit, tr);
433 if (!ret) {
434 rcu_assign_pointer(tr->exit_syscall_files[num], file);
435 tr->sys_refcount_exit++;
436 }
437 mutex_unlock(&syscall_trace_lock);
438 return ret;
439}
440
441static void unreg_event_syscall_exit(struct trace_event_file *file,
442 struct trace_event_call *call)
443{
444 struct trace_array *tr = file->tr;
445 int num;
446
447 num = ((struct syscall_metadata *)call->data)->syscall_nr;
448 if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
449 return;
450 mutex_lock(&syscall_trace_lock);
451 tr->sys_refcount_exit--;
452 RCU_INIT_POINTER(tr->exit_syscall_files[num], NULL);
453 if (!tr->sys_refcount_exit)
454 unregister_trace_sys_exit(ftrace_syscall_exit, tr);
455 mutex_unlock(&syscall_trace_lock);
456}
457
458static int __init init_syscall_trace(struct trace_event_call *call)
459{
460 int id;
461 int num;
462
463 num = ((struct syscall_metadata *)call->data)->syscall_nr;
464 if (num < 0 || num >= NR_syscalls) {
465 pr_debug("syscall %s metadata not mapped, disabling ftrace event\n",
466 ((struct syscall_metadata *)call->data)->name);
467 return -ENOSYS;
468 }
469
470 if (set_syscall_print_fmt(call) < 0)
471 return -ENOMEM;
472
473 id = trace_event_raw_init(call);
474
475 if (id < 0) {
476 free_syscall_print_fmt(call);
477 return id;
478 }
479
480 return id;
481}
482
483static struct trace_event_fields __refdata syscall_enter_fields_array[] = {
484 SYSCALL_FIELD(int, __syscall_nr),
485 { .type = TRACE_FUNCTION_TYPE,
486 .define_fields = syscall_enter_define_fields },
487 {}
488};
489
490struct trace_event_functions enter_syscall_print_funcs = {
491 .trace = print_syscall_enter,
492};
493
494struct trace_event_functions exit_syscall_print_funcs = {
495 .trace = print_syscall_exit,
496};
497
498struct trace_event_class __refdata event_class_syscall_enter = {
499 .system = "syscalls",
500 .reg = syscall_enter_register,
501 .fields_array = syscall_enter_fields_array,
502 .get_fields = syscall_get_enter_fields,
503 .raw_init = init_syscall_trace,
504};
505
506struct trace_event_class __refdata event_class_syscall_exit = {
507 .system = "syscalls",
508 .reg = syscall_exit_register,
509 .fields_array = (struct trace_event_fields[]){
510 SYSCALL_FIELD(int, __syscall_nr),
511 SYSCALL_FIELD(long, ret),
512 {}
513 },
514 .fields = LIST_HEAD_INIT(event_class_syscall_exit.fields),
515 .raw_init = init_syscall_trace,
516};
517
518unsigned long __init __weak arch_syscall_addr(int nr)
519{
520 return (unsigned long)sys_call_table[nr];
521}
522
523void __init init_ftrace_syscalls(void)
524{
525 struct syscall_metadata *meta;
526 unsigned long addr;
527 int i;
528 void *ret;
529
530 if (!IS_ENABLED(CONFIG_HAVE_SPARSE_SYSCALL_NR)) {
531 syscalls_metadata = kcalloc(NR_syscalls,
532 sizeof(*syscalls_metadata),
533 GFP_KERNEL);
534 if (!syscalls_metadata) {
535 WARN_ON(1);
536 return;
537 }
538 }
539
540 for (i = 0; i < NR_syscalls; i++) {
541 addr = arch_syscall_addr(i);
542 meta = find_syscall_meta(addr);
543 if (!meta)
544 continue;
545
546 meta->syscall_nr = i;
547
548 if (!IS_ENABLED(CONFIG_HAVE_SPARSE_SYSCALL_NR)) {
549 syscalls_metadata[i] = meta;
550 } else {
551 ret = xa_store(&syscalls_metadata_sparse, i, meta,
552 GFP_KERNEL);
553 WARN(xa_is_err(ret),
554 "Syscall memory allocation failed\n");
555 }
556
557 }
558}
559
560#ifdef CONFIG_PERF_EVENTS
561
562static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
563static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
564static int sys_perf_refcount_enter;
565static int sys_perf_refcount_exit;
566
567static int perf_call_bpf_enter(struct trace_event_call *call, struct pt_regs *regs,
568 struct syscall_metadata *sys_data,
569 struct syscall_trace_enter *rec)
570{
571 struct syscall_tp_t {
572 struct trace_entry ent;
573 int syscall_nr;
574 unsigned long args[SYSCALL_DEFINE_MAXARGS];
575 } __aligned(8) param;
576 int i;
577
578 BUILD_BUG_ON(sizeof(param.ent) < sizeof(void *));
579
580 /* bpf prog requires 'regs' to be the first member in the ctx (a.k.a. ¶m) */
581 perf_fetch_caller_regs(regs);
582 *(struct pt_regs **)¶m = regs;
583 param.syscall_nr = rec->nr;
584 for (i = 0; i < sys_data->nb_args; i++)
585 param.args[i] = rec->args[i];
586 return trace_call_bpf(call, ¶m);
587}
588
589static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id)
590{
591 struct syscall_metadata *sys_data;
592 struct syscall_trace_enter *rec;
593 struct pt_regs *fake_regs;
594 struct hlist_head *head;
595 unsigned long args[6];
596 bool valid_prog_array;
597 int syscall_nr;
598 int rctx;
599 int size;
600
601 /*
602 * Syscall probe called with preemption enabled, but the ring
603 * buffer and per-cpu data require preemption to be disabled.
604 */
605 might_fault();
606 guard(preempt_notrace)();
607
608 syscall_nr = trace_get_syscall_nr(current, regs);
609 if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
610 return;
611 if (!test_bit(syscall_nr, enabled_perf_enter_syscalls))
612 return;
613
614 sys_data = syscall_nr_to_meta(syscall_nr);
615 if (!sys_data)
616 return;
617
618 head = this_cpu_ptr(sys_data->enter_event->perf_events);
619 valid_prog_array = bpf_prog_array_valid(sys_data->enter_event);
620 if (!valid_prog_array && hlist_empty(head))
621 return;
622
623 /* get the size after alignment with the u32 buffer size field */
624 size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec);
625 size = ALIGN(size + sizeof(u32), sizeof(u64));
626 size -= sizeof(u32);
627
628 rec = perf_trace_buf_alloc(size, &fake_regs, &rctx);
629 if (!rec)
630 return;
631
632 rec->nr = syscall_nr;
633 syscall_get_arguments(current, regs, args);
634 memcpy(&rec->args, args, sizeof(unsigned long) * sys_data->nb_args);
635
636 if ((valid_prog_array &&
637 !perf_call_bpf_enter(sys_data->enter_event, fake_regs, sys_data, rec)) ||
638 hlist_empty(head)) {
639 perf_swevent_put_recursion_context(rctx);
640 return;
641 }
642
643 perf_trace_buf_submit(rec, size, rctx,
644 sys_data->enter_event->event.type, 1, regs,
645 head, NULL);
646}
647
648static int perf_sysenter_enable(struct trace_event_call *call)
649{
650 int ret = 0;
651 int num;
652
653 num = ((struct syscall_metadata *)call->data)->syscall_nr;
654
655 mutex_lock(&syscall_trace_lock);
656 if (!sys_perf_refcount_enter)
657 ret = register_trace_sys_enter(perf_syscall_enter, NULL);
658 if (ret) {
659 pr_info("event trace: Could not activate syscall entry trace point");
660 } else {
661 set_bit(num, enabled_perf_enter_syscalls);
662 sys_perf_refcount_enter++;
663 }
664 mutex_unlock(&syscall_trace_lock);
665 return ret;
666}
667
668static void perf_sysenter_disable(struct trace_event_call *call)
669{
670 int num;
671
672 num = ((struct syscall_metadata *)call->data)->syscall_nr;
673
674 mutex_lock(&syscall_trace_lock);
675 sys_perf_refcount_enter--;
676 clear_bit(num, enabled_perf_enter_syscalls);
677 if (!sys_perf_refcount_enter)
678 unregister_trace_sys_enter(perf_syscall_enter, NULL);
679 mutex_unlock(&syscall_trace_lock);
680}
681
682static int perf_call_bpf_exit(struct trace_event_call *call, struct pt_regs *regs,
683 struct syscall_trace_exit *rec)
684{
685 struct syscall_tp_t {
686 struct trace_entry ent;
687 int syscall_nr;
688 unsigned long ret;
689 } __aligned(8) param;
690
691 /* bpf prog requires 'regs' to be the first member in the ctx (a.k.a. ¶m) */
692 perf_fetch_caller_regs(regs);
693 *(struct pt_regs **)¶m = regs;
694 param.syscall_nr = rec->nr;
695 param.ret = rec->ret;
696 return trace_call_bpf(call, ¶m);
697}
698
699static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret)
700{
701 struct syscall_metadata *sys_data;
702 struct syscall_trace_exit *rec;
703 struct pt_regs *fake_regs;
704 struct hlist_head *head;
705 bool valid_prog_array;
706 int syscall_nr;
707 int rctx;
708 int size;
709
710 /*
711 * Syscall probe called with preemption enabled, but the ring
712 * buffer and per-cpu data require preemption to be disabled.
713 */
714 might_fault();
715 guard(preempt_notrace)();
716
717 syscall_nr = trace_get_syscall_nr(current, regs);
718 if (syscall_nr < 0 || syscall_nr >= NR_syscalls)
719 return;
720 if (!test_bit(syscall_nr, enabled_perf_exit_syscalls))
721 return;
722
723 sys_data = syscall_nr_to_meta(syscall_nr);
724 if (!sys_data)
725 return;
726
727 head = this_cpu_ptr(sys_data->exit_event->perf_events);
728 valid_prog_array = bpf_prog_array_valid(sys_data->exit_event);
729 if (!valid_prog_array && hlist_empty(head))
730 return;
731
732 /* We can probably do that at build time */
733 size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64));
734 size -= sizeof(u32);
735
736 rec = perf_trace_buf_alloc(size, &fake_regs, &rctx);
737 if (!rec)
738 return;
739
740 rec->nr = syscall_nr;
741 rec->ret = syscall_get_return_value(current, regs);
742
743 if ((valid_prog_array &&
744 !perf_call_bpf_exit(sys_data->exit_event, fake_regs, rec)) ||
745 hlist_empty(head)) {
746 perf_swevent_put_recursion_context(rctx);
747 return;
748 }
749
750 perf_trace_buf_submit(rec, size, rctx, sys_data->exit_event->event.type,
751 1, regs, head, NULL);
752}
753
754static int perf_sysexit_enable(struct trace_event_call *call)
755{
756 int ret = 0;
757 int num;
758
759 num = ((struct syscall_metadata *)call->data)->syscall_nr;
760
761 mutex_lock(&syscall_trace_lock);
762 if (!sys_perf_refcount_exit)
763 ret = register_trace_sys_exit(perf_syscall_exit, NULL);
764 if (ret) {
765 pr_info("event trace: Could not activate syscall exit trace point");
766 } else {
767 set_bit(num, enabled_perf_exit_syscalls);
768 sys_perf_refcount_exit++;
769 }
770 mutex_unlock(&syscall_trace_lock);
771 return ret;
772}
773
774static void perf_sysexit_disable(struct trace_event_call *call)
775{
776 int num;
777
778 num = ((struct syscall_metadata *)call->data)->syscall_nr;
779
780 mutex_lock(&syscall_trace_lock);
781 sys_perf_refcount_exit--;
782 clear_bit(num, enabled_perf_exit_syscalls);
783 if (!sys_perf_refcount_exit)
784 unregister_trace_sys_exit(perf_syscall_exit, NULL);
785 mutex_unlock(&syscall_trace_lock);
786}
787
788#endif /* CONFIG_PERF_EVENTS */
789
790static int syscall_enter_register(struct trace_event_call *event,
791 enum trace_reg type, void *data)
792{
793 struct trace_event_file *file = data;
794
795 switch (type) {
796 case TRACE_REG_REGISTER:
797 return reg_event_syscall_enter(file, event);
798 case TRACE_REG_UNREGISTER:
799 unreg_event_syscall_enter(file, event);
800 return 0;
801
802#ifdef CONFIG_PERF_EVENTS
803 case TRACE_REG_PERF_REGISTER:
804 return perf_sysenter_enable(event);
805 case TRACE_REG_PERF_UNREGISTER:
806 perf_sysenter_disable(event);
807 return 0;
808 case TRACE_REG_PERF_OPEN:
809 case TRACE_REG_PERF_CLOSE:
810 case TRACE_REG_PERF_ADD:
811 case TRACE_REG_PERF_DEL:
812 return 0;
813#endif
814 }
815 return 0;
816}
817
818static int syscall_exit_register(struct trace_event_call *event,
819 enum trace_reg type, void *data)
820{
821 struct trace_event_file *file = data;
822
823 switch (type) {
824 case TRACE_REG_REGISTER:
825 return reg_event_syscall_exit(file, event);
826 case TRACE_REG_UNREGISTER:
827 unreg_event_syscall_exit(file, event);
828 return 0;
829
830#ifdef CONFIG_PERF_EVENTS
831 case TRACE_REG_PERF_REGISTER:
832 return perf_sysexit_enable(event);
833 case TRACE_REG_PERF_UNREGISTER:
834 perf_sysexit_disable(event);
835 return 0;
836 case TRACE_REG_PERF_OPEN:
837 case TRACE_REG_PERF_CLOSE:
838 case TRACE_REG_PERF_ADD:
839 case TRACE_REG_PERF_DEL:
840 return 0;
841#endif
842 }
843 return 0;
844}