Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * trace event based perf event profiling/tracing
4 : *
5 : * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra
6 : * Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com>
7 : */
8 :
9 : #include <linux/module.h>
10 : #include <linux/kprobes.h>
11 : #include <linux/security.h>
12 : #include "trace.h"
13 : #include "trace_probe.h"
14 :
15 : static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS];
16 :
17 : /*
18 : * Force it to be aligned to unsigned long to avoid misaligned accesses
19 : * suprises
20 : */
21 : typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
22 : perf_trace_t;
23 :
24 : /* Count the events in use (per event id, not per instance) */
25 : static int total_ref_count;
26 :
27 0 : static int perf_trace_event_perm(struct trace_event_call *tp_event,
28 : struct perf_event *p_event)
29 : {
30 0 : int ret;
31 :
32 0 : if (tp_event->perf_perm) {
33 0 : ret = tp_event->perf_perm(tp_event, p_event);
34 0 : if (ret)
35 : return ret;
36 : }
37 :
38 : /*
39 : * We checked and allowed to create parent,
40 : * allow children without checking.
41 : */
42 0 : if (p_event->parent)
43 : return 0;
44 :
45 : /*
46 : * It's ok to check current process (owner) permissions in here,
47 : * because code below is called only via perf_event_open syscall.
48 : */
49 :
50 : /* The ftrace function trace is allowed only for root. */
51 0 : if (ftrace_event_is_function(tp_event)) {
52 0 : ret = perf_allow_tracepoint(&p_event->attr);
53 0 : if (ret)
54 : return ret;
55 :
56 0 : if (!is_sampling_event(p_event))
57 : return 0;
58 :
59 : /*
60 : * We don't allow user space callchains for function trace
61 : * event, due to issues with page faults while tracing page
62 : * fault handler and its overall trickiness nature.
63 : */
64 0 : if (!p_event->attr.exclude_callchain_user)
65 : return -EINVAL;
66 :
67 : /*
68 : * Same reason to disable user stack dump as for user space
69 : * callchains above.
70 : */
71 0 : if (p_event->attr.sample_type & PERF_SAMPLE_STACK_USER)
72 : return -EINVAL;
73 : }
74 :
75 : /* No tracing, just counting, so no obvious leak */
76 0 : if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
77 : return 0;
78 :
79 : /* Some events are ok to be traced by non-root users... */
80 0 : if (p_event->attach_state == PERF_ATTACH_TASK) {
81 0 : if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY)
82 : return 0;
83 : }
84 :
85 : /*
86 : * ...otherwise raw tracepoint data can be a severe data leak,
87 : * only allow root to have these.
88 : */
89 0 : ret = perf_allow_tracepoint(&p_event->attr);
90 0 : if (ret)
91 0 : return ret;
92 :
93 : return 0;
94 : }
95 :
96 0 : static int perf_trace_event_reg(struct trace_event_call *tp_event,
97 : struct perf_event *p_event)
98 : {
99 0 : struct hlist_head __percpu *list;
100 0 : int ret = -ENOMEM;
101 0 : int cpu;
102 :
103 0 : p_event->tp_event = tp_event;
104 0 : if (tp_event->perf_refcount++ > 0)
105 : return 0;
106 :
107 0 : list = alloc_percpu(struct hlist_head);
108 0 : if (!list)
109 0 : goto fail;
110 :
111 0 : for_each_possible_cpu(cpu)
112 0 : INIT_HLIST_HEAD(per_cpu_ptr(list, cpu));
113 :
114 0 : tp_event->perf_events = list;
115 :
116 0 : if (!total_ref_count) {
117 : char __percpu *buf;
118 : int i;
119 :
120 0 : for (i = 0; i < PERF_NR_CONTEXTS; i++) {
121 0 : buf = (char __percpu *)alloc_percpu(perf_trace_t);
122 0 : if (!buf)
123 0 : goto fail;
124 :
125 0 : perf_trace_buf[i] = buf;
126 : }
127 : }
128 :
129 0 : ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL);
130 0 : if (ret)
131 0 : goto fail;
132 :
133 0 : total_ref_count++;
134 0 : return 0;
135 :
136 0 : fail:
137 0 : if (!total_ref_count) {
138 : int i;
139 :
140 0 : for (i = 0; i < PERF_NR_CONTEXTS; i++) {
141 0 : free_percpu(perf_trace_buf[i]);
142 0 : perf_trace_buf[i] = NULL;
143 : }
144 : }
145 :
146 0 : if (!--tp_event->perf_refcount) {
147 0 : free_percpu(tp_event->perf_events);
148 0 : tp_event->perf_events = NULL;
149 : }
150 :
151 : return ret;
152 : }
153 :
154 0 : static void perf_trace_event_unreg(struct perf_event *p_event)
155 : {
156 0 : struct trace_event_call *tp_event = p_event->tp_event;
157 0 : int i;
158 :
159 0 : if (--tp_event->perf_refcount > 0)
160 0 : goto out;
161 :
162 0 : tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL);
163 :
164 : /*
165 : * Ensure our callback won't be called anymore. The buffers
166 : * will be freed after that.
167 : */
168 0 : tracepoint_synchronize_unregister();
169 :
170 0 : free_percpu(tp_event->perf_events);
171 0 : tp_event->perf_events = NULL;
172 :
173 0 : if (!--total_ref_count) {
174 0 : for (i = 0; i < PERF_NR_CONTEXTS; i++) {
175 0 : free_percpu(perf_trace_buf[i]);
176 0 : perf_trace_buf[i] = NULL;
177 : }
178 : }
179 0 : out:
180 0 : module_put(tp_event->mod);
181 0 : }
182 :
183 0 : static int perf_trace_event_open(struct perf_event *p_event)
184 : {
185 0 : struct trace_event_call *tp_event = p_event->tp_event;
186 0 : return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event);
187 : }
188 :
189 0 : static void perf_trace_event_close(struct perf_event *p_event)
190 : {
191 0 : struct trace_event_call *tp_event = p_event->tp_event;
192 0 : tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);
193 0 : }
194 :
195 0 : static int perf_trace_event_init(struct trace_event_call *tp_event,
196 : struct perf_event *p_event)
197 : {
198 0 : int ret;
199 :
200 0 : ret = perf_trace_event_perm(tp_event, p_event);
201 0 : if (ret)
202 : return ret;
203 :
204 0 : ret = perf_trace_event_reg(tp_event, p_event);
205 0 : if (ret)
206 : return ret;
207 :
208 0 : ret = perf_trace_event_open(p_event);
209 0 : if (ret) {
210 0 : perf_trace_event_unreg(p_event);
211 0 : return ret;
212 : }
213 :
214 : return 0;
215 : }
216 :
217 0 : int perf_trace_init(struct perf_event *p_event)
218 : {
219 0 : struct trace_event_call *tp_event;
220 0 : u64 event_id = p_event->attr.config;
221 0 : int ret = -EINVAL;
222 :
223 0 : mutex_lock(&event_mutex);
224 0 : list_for_each_entry(tp_event, &ftrace_events, list) {
225 0 : if (tp_event->event.type == event_id &&
226 0 : tp_event->class && tp_event->class->reg &&
227 0 : try_module_get(tp_event->mod)) {
228 0 : ret = perf_trace_event_init(tp_event, p_event);
229 0 : if (ret)
230 0 : module_put(tp_event->mod);
231 : break;
232 : }
233 : }
234 0 : mutex_unlock(&event_mutex);
235 :
236 0 : return ret;
237 : }
238 :
239 0 : void perf_trace_destroy(struct perf_event *p_event)
240 : {
241 0 : mutex_lock(&event_mutex);
242 0 : perf_trace_event_close(p_event);
243 0 : perf_trace_event_unreg(p_event);
244 0 : mutex_unlock(&event_mutex);
245 0 : }
246 :
247 : #ifdef CONFIG_KPROBE_EVENTS
248 : int perf_kprobe_init(struct perf_event *p_event, bool is_retprobe)
249 : {
250 : int ret;
251 : char *func = NULL;
252 : struct trace_event_call *tp_event;
253 :
254 : if (p_event->attr.kprobe_func) {
255 : func = kzalloc(KSYM_NAME_LEN, GFP_KERNEL);
256 : if (!func)
257 : return -ENOMEM;
258 : ret = strncpy_from_user(
259 : func, u64_to_user_ptr(p_event->attr.kprobe_func),
260 : KSYM_NAME_LEN);
261 : if (ret == KSYM_NAME_LEN)
262 : ret = -E2BIG;
263 : if (ret < 0)
264 : goto out;
265 :
266 : if (func[0] == '\0') {
267 : kfree(func);
268 : func = NULL;
269 : }
270 : }
271 :
272 : tp_event = create_local_trace_kprobe(
273 : func, (void *)(unsigned long)(p_event->attr.kprobe_addr),
274 : p_event->attr.probe_offset, is_retprobe);
275 : if (IS_ERR(tp_event)) {
276 : ret = PTR_ERR(tp_event);
277 : goto out;
278 : }
279 :
280 : mutex_lock(&event_mutex);
281 : ret = perf_trace_event_init(tp_event, p_event);
282 : if (ret)
283 : destroy_local_trace_kprobe(tp_event);
284 : mutex_unlock(&event_mutex);
285 : out:
286 : kfree(func);
287 : return ret;
288 : }
289 :
290 : void perf_kprobe_destroy(struct perf_event *p_event)
291 : {
292 : mutex_lock(&event_mutex);
293 : perf_trace_event_close(p_event);
294 : perf_trace_event_unreg(p_event);
295 : mutex_unlock(&event_mutex);
296 :
297 : destroy_local_trace_kprobe(p_event->tp_event);
298 : }
299 : #endif /* CONFIG_KPROBE_EVENTS */
300 :
301 : #ifdef CONFIG_UPROBE_EVENTS
302 : int perf_uprobe_init(struct perf_event *p_event,
303 : unsigned long ref_ctr_offset, bool is_retprobe)
304 : {
305 : int ret;
306 : char *path = NULL;
307 : struct trace_event_call *tp_event;
308 :
309 : if (!p_event->attr.uprobe_path)
310 : return -EINVAL;
311 :
312 : path = strndup_user(u64_to_user_ptr(p_event->attr.uprobe_path),
313 : PATH_MAX);
314 : if (IS_ERR(path)) {
315 : ret = PTR_ERR(path);
316 : return (ret == -EINVAL) ? -E2BIG : ret;
317 : }
318 : if (path[0] == '\0') {
319 : ret = -EINVAL;
320 : goto out;
321 : }
322 :
323 : tp_event = create_local_trace_uprobe(path, p_event->attr.probe_offset,
324 : ref_ctr_offset, is_retprobe);
325 : if (IS_ERR(tp_event)) {
326 : ret = PTR_ERR(tp_event);
327 : goto out;
328 : }
329 :
330 : /*
331 : * local trace_uprobe need to hold event_mutex to call
332 : * uprobe_buffer_enable() and uprobe_buffer_disable().
333 : * event_mutex is not required for local trace_kprobes.
334 : */
335 : mutex_lock(&event_mutex);
336 : ret = perf_trace_event_init(tp_event, p_event);
337 : if (ret)
338 : destroy_local_trace_uprobe(tp_event);
339 : mutex_unlock(&event_mutex);
340 : out:
341 : kfree(path);
342 : return ret;
343 : }
344 :
345 : void perf_uprobe_destroy(struct perf_event *p_event)
346 : {
347 : mutex_lock(&event_mutex);
348 : perf_trace_event_close(p_event);
349 : perf_trace_event_unreg(p_event);
350 : mutex_unlock(&event_mutex);
351 : destroy_local_trace_uprobe(p_event->tp_event);
352 : }
353 : #endif /* CONFIG_UPROBE_EVENTS */
354 :
355 0 : int perf_trace_add(struct perf_event *p_event, int flags)
356 : {
357 0 : struct trace_event_call *tp_event = p_event->tp_event;
358 :
359 0 : if (!(flags & PERF_EF_START))
360 0 : p_event->hw.state = PERF_HES_STOPPED;
361 :
362 : /*
363 : * If TRACE_REG_PERF_ADD returns false; no custom action was performed
364 : * and we need to take the default action of enqueueing our event on
365 : * the right per-cpu hlist.
366 : */
367 0 : if (!tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event)) {
368 0 : struct hlist_head __percpu *pcpu_list;
369 0 : struct hlist_head *list;
370 :
371 0 : pcpu_list = tp_event->perf_events;
372 0 : if (WARN_ON_ONCE(!pcpu_list))
373 : return -EINVAL;
374 :
375 0 : list = this_cpu_ptr(pcpu_list);
376 0 : hlist_add_head_rcu(&p_event->hlist_entry, list);
377 : }
378 :
379 : return 0;
380 : }
381 :
382 0 : void perf_trace_del(struct perf_event *p_event, int flags)
383 : {
384 0 : struct trace_event_call *tp_event = p_event->tp_event;
385 :
386 : /*
387 : * If TRACE_REG_PERF_DEL returns false; no custom action was performed
388 : * and we need to take the default action of dequeueing our event from
389 : * the right per-cpu hlist.
390 : */
391 0 : if (!tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event))
392 0 : hlist_del_rcu(&p_event->hlist_entry);
393 0 : }
394 :
395 0 : void *perf_trace_buf_alloc(int size, struct pt_regs **regs, int *rctxp)
396 : {
397 0 : char *raw_data;
398 0 : int rctx;
399 :
400 0 : BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
401 :
402 0 : if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
403 : "perf buffer not large enough"))
404 : return NULL;
405 :
406 0 : *rctxp = rctx = perf_swevent_get_recursion_context();
407 0 : if (rctx < 0)
408 : return NULL;
409 :
410 0 : if (regs)
411 0 : *regs = this_cpu_ptr(&__perf_regs[rctx]);
412 0 : raw_data = this_cpu_ptr(perf_trace_buf[rctx]);
413 :
414 : /* zero the dead bytes from align to not leak stack to user */
415 0 : memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
416 0 : return raw_data;
417 : }
418 : EXPORT_SYMBOL_GPL(perf_trace_buf_alloc);
419 : NOKPROBE_SYMBOL(perf_trace_buf_alloc);
420 :
421 0 : void perf_trace_buf_update(void *record, u16 type)
422 : {
423 0 : struct trace_entry *entry = record;
424 :
425 0 : tracing_generic_entry_update(entry, type, tracing_gen_ctx());
426 0 : }
427 : NOKPROBE_SYMBOL(perf_trace_buf_update);
428 :
429 : #ifdef CONFIG_FUNCTION_TRACER
430 : static void
431 : perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
432 : struct ftrace_ops *ops, struct ftrace_regs *fregs)
433 : {
434 : struct ftrace_entry *entry;
435 : struct perf_event *event;
436 : struct hlist_head head;
437 : struct pt_regs regs;
438 : int rctx;
439 : int bit;
440 :
441 : if (!rcu_is_watching())
442 : return;
443 :
444 : if ((unsigned long)ops->private != smp_processor_id())
445 : return;
446 :
447 : bit = ftrace_test_recursion_trylock(ip, parent_ip);
448 : if (bit < 0)
449 : return;
450 :
451 : event = container_of(ops, struct perf_event, ftrace_ops);
452 :
453 : /*
454 : * @event->hlist entry is NULL (per INIT_HLIST_NODE), and all
455 : * the perf code does is hlist_for_each_entry_rcu(), so we can
456 : * get away with simply setting the @head.first pointer in order
457 : * to create a singular list.
458 : */
459 : head.first = &event->hlist_entry;
460 :
461 : #define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
462 : sizeof(u64)) - sizeof(u32))
463 :
464 : BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);
465 :
466 : memset(®s, 0, sizeof(regs));
467 : perf_fetch_caller_regs(®s);
468 :
469 : entry = perf_trace_buf_alloc(ENTRY_SIZE, NULL, &rctx);
470 : if (!entry)
471 : goto out;
472 :
473 : entry->ip = ip;
474 : entry->parent_ip = parent_ip;
475 : perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, TRACE_FN,
476 : 1, ®s, &head, NULL);
477 :
478 : out:
479 : ftrace_test_recursion_unlock(bit);
480 : #undef ENTRY_SIZE
481 : }
482 :
483 : static int perf_ftrace_function_register(struct perf_event *event)
484 : {
485 : struct ftrace_ops *ops = &event->ftrace_ops;
486 :
487 : ops->func = perf_ftrace_function_call;
488 : ops->private = (void *)(unsigned long)nr_cpu_ids;
489 :
490 : return register_ftrace_function(ops);
491 : }
492 :
493 : static int perf_ftrace_function_unregister(struct perf_event *event)
494 : {
495 : struct ftrace_ops *ops = &event->ftrace_ops;
496 : int ret = unregister_ftrace_function(ops);
497 : ftrace_free_filter(ops);
498 : return ret;
499 : }
500 :
501 : int perf_ftrace_event_register(struct trace_event_call *call,
502 : enum trace_reg type, void *data)
503 : {
504 : struct perf_event *event = data;
505 :
506 : switch (type) {
507 : case TRACE_REG_REGISTER:
508 : case TRACE_REG_UNREGISTER:
509 : break;
510 : case TRACE_REG_PERF_REGISTER:
511 : case TRACE_REG_PERF_UNREGISTER:
512 : return 0;
513 : case TRACE_REG_PERF_OPEN:
514 : return perf_ftrace_function_register(data);
515 : case TRACE_REG_PERF_CLOSE:
516 : return perf_ftrace_function_unregister(data);
517 : case TRACE_REG_PERF_ADD:
518 : event->ftrace_ops.private = (void *)(unsigned long)smp_processor_id();
519 : return 1;
520 : case TRACE_REG_PERF_DEL:
521 : event->ftrace_ops.private = (void *)(unsigned long)nr_cpu_ids;
522 : return 1;
523 : }
524 :
525 : return -EINVAL;
526 : }
527 : #endif /* CONFIG_FUNCTION_TRACER */
|
