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