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
16 static DEFINE_MUTEX(syscall_trace_lock);
17
18 static int syscall_enter_register(struct trace_event_call *event,
19 enum trace_reg type, void *data);
20 static int syscall_exit_register(struct trace_event_call *event,
21 enum trace_reg type, void *data);
22
23 static struct list_head *
syscall_get_enter_fields(struct trace_event_call * call)24 syscall_get_enter_fields(struct trace_event_call *call)
25 {
26 struct syscall_metadata *entry = call->data;
27
28 return &entry->enter_fields;
29 }
30
31 extern struct syscall_metadata *__start_syscalls_metadata[];
32 extern struct syscall_metadata *__stop_syscalls_metadata[];
33
34 static DEFINE_XARRAY(syscalls_metadata_sparse);
35 static struct syscall_metadata **syscalls_metadata;
36
37 #ifndef ARCH_HAS_SYSCALL_MATCH_SYM_NAME
arch_syscall_match_sym_name(const char * sym,const char * name)38 static 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 */
66 static int
trace_get_syscall_nr(struct task_struct * task,struct pt_regs * regs)67 trace_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
75 static inline int
trace_get_syscall_nr(struct task_struct * task,struct pt_regs * regs)76 trace_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
82 static __init struct syscall_metadata *
find_syscall_meta(unsigned long syscall)83 find_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
syscall_nr_to_meta(int nr)104 static 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
get_syscall_name(int syscall)115 const 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
126 static enum print_line_t
print_syscall_enter(struct trace_iterator * iter,int flags,struct trace_event * event)127 print_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, ')');
167 end:
168 trace_seq_putc(s, '\n');
169
170 return trace_handle_return(s);
171 }
172
173 static enum print_line_t
print_syscall_exit(struct trace_iterator * iter,int flags,struct trace_event * event)174 print_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 extern 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
211 static int __init
__set_enter_print_fmt(struct syscall_metadata * entry,char * buf,int len)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
set_syscall_print_fmt(struct trace_event_call * call)239 static 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
free_syscall_print_fmt(struct trace_event_call * call)264 static 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
syscall_enter_define_fields(struct trace_event_call * call)272 static 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
ftrace_syscall_enter(void * data,struct pt_regs * regs,long id)293 static 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
ftrace_syscall_exit(void * data,struct pt_regs * regs,long ret)343 static 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
reg_event_syscall_enter(struct trace_event_file * file,struct trace_event_call * call)389 static 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
unreg_event_syscall_enter(struct trace_event_file * file,struct trace_event_call * call)410 static 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
reg_event_syscall_exit(struct trace_event_file * file,struct trace_event_call * call)427 static 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
unreg_event_syscall_exit(struct trace_event_file * file,struct trace_event_call * call)448 static 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
init_syscall_trace(struct trace_event_call * call)465 static 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
490 static 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
497 struct trace_event_functions enter_syscall_print_funcs = {
498 .trace = print_syscall_enter,
499 };
500
501 struct trace_event_functions exit_syscall_print_funcs = {
502 .trace = print_syscall_exit,
503 };
504
505 struct 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
513 struct 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
arch_syscall_addr(int nr)525 unsigned long __init __weak arch_syscall_addr(int nr)
526 {
527 return (unsigned long)sys_call_table[nr];
528 }
529
init_ftrace_syscalls(void)530 void __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
569 static DECLARE_BITMAP(enabled_perf_enter_syscalls, NR_syscalls);
570 static DECLARE_BITMAP(enabled_perf_exit_syscalls, NR_syscalls);
571 static int sys_perf_refcount_enter;
572 static int sys_perf_refcount_exit;
573
perf_call_bpf_enter(struct trace_event_call * call,struct pt_regs * regs,struct syscall_metadata * sys_data,struct syscall_trace_enter * rec)574 static 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
perf_syscall_enter(void * ignore,struct pt_regs * regs,long id)592 static 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
perf_sysenter_enable(struct trace_event_call * call)643 static 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
perf_sysenter_disable(struct trace_event_call * call)663 static 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
perf_call_bpf_exit(struct trace_event_call * call,struct pt_regs * regs,struct syscall_trace_exit * rec)677 static 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
perf_syscall_exit(void * ignore,struct pt_regs * regs,long ret)692 static 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
perf_sysexit_enable(struct trace_event_call * call)739 static 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
perf_sysexit_disable(struct trace_event_call * call)759 static 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
syscall_enter_register(struct trace_event_call * event,enum trace_reg type,void * data)775 static 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
syscall_exit_register(struct trace_event_call * event,enum trace_reg type,void * data)803 static 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 }
830