1 // SPDX-License-Identifier: GPL-2.0
3 * trace event based perf event profiling/tracing
5 * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra
6 * Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com>
9 #include <linux/module.h>
10 #include <linux/kprobes.h>
12 #include "trace_probe.h"
14 static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS];
17 * Force it to be aligned to unsigned long to avoid misaligned accesses
20 typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
23 /* Count the events in use (per event id, not per instance) */
24 static int total_ref_count;
26 static int perf_trace_event_perm(struct trace_event_call *tp_event,
27 struct perf_event *p_event)
29 if (tp_event->perf_perm) {
30 int ret = tp_event->perf_perm(tp_event, p_event);
36 * We checked and allowed to create parent,
37 * allow children without checking.
43 * It's ok to check current process (owner) permissions in here,
44 * because code below is called only via perf_event_open syscall.
47 /* The ftrace function trace is allowed only for root. */
48 if (ftrace_event_is_function(tp_event)) {
49 if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
52 if (!is_sampling_event(p_event))
56 * We don't allow user space callchains for function trace
57 * event, due to issues with page faults while tracing page
58 * fault handler and its overall trickiness nature.
60 if (!p_event->attr.exclude_callchain_user)
64 * Same reason to disable user stack dump as for user space
67 if (p_event->attr.sample_type & PERF_SAMPLE_STACK_USER)
71 /* No tracing, just counting, so no obvious leak */
72 if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
75 /* Some events are ok to be traced by non-root users... */
76 if (p_event->attach_state == PERF_ATTACH_TASK) {
77 if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY)
82 * ...otherwise raw tracepoint data can be a severe data leak,
83 * only allow root to have these.
85 if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
91 static int perf_trace_event_reg(struct trace_event_call *tp_event,
92 struct perf_event *p_event)
94 struct hlist_head __percpu *list;
98 p_event->tp_event = tp_event;
99 if (tp_event->perf_refcount++ > 0)
102 list = alloc_percpu(struct hlist_head);
106 for_each_possible_cpu(cpu)
107 INIT_HLIST_HEAD(per_cpu_ptr(list, cpu));
109 tp_event->perf_events = list;
111 if (!total_ref_count) {
115 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
116 buf = (char __percpu *)alloc_percpu(perf_trace_t);
120 perf_trace_buf[i] = buf;
124 ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL);
132 if (!total_ref_count) {
135 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
136 free_percpu(perf_trace_buf[i]);
137 perf_trace_buf[i] = NULL;
141 if (!--tp_event->perf_refcount) {
142 free_percpu(tp_event->perf_events);
143 tp_event->perf_events = NULL;
149 static void perf_trace_event_unreg(struct perf_event *p_event)
151 struct trace_event_call *tp_event = p_event->tp_event;
154 if (--tp_event->perf_refcount > 0)
157 tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL);
160 * Ensure our callback won't be called anymore. The buffers
161 * will be freed after that.
163 tracepoint_synchronize_unregister();
165 free_percpu(tp_event->perf_events);
166 tp_event->perf_events = NULL;
168 if (!--total_ref_count) {
169 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
170 free_percpu(perf_trace_buf[i]);
171 perf_trace_buf[i] = NULL;
175 module_put(tp_event->mod);
178 static int perf_trace_event_open(struct perf_event *p_event)
180 struct trace_event_call *tp_event = p_event->tp_event;
181 return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event);
184 static void perf_trace_event_close(struct perf_event *p_event)
186 struct trace_event_call *tp_event = p_event->tp_event;
187 tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);
190 static int perf_trace_event_init(struct trace_event_call *tp_event,
191 struct perf_event *p_event)
195 ret = perf_trace_event_perm(tp_event, p_event);
199 ret = perf_trace_event_reg(tp_event, p_event);
203 ret = perf_trace_event_open(p_event);
205 perf_trace_event_unreg(p_event);
212 int perf_trace_init(struct perf_event *p_event)
214 struct trace_event_call *tp_event;
215 u64 event_id = p_event->attr.config;
218 mutex_lock(&event_mutex);
219 list_for_each_entry(tp_event, &ftrace_events, list) {
220 if (tp_event->event.type == event_id &&
221 tp_event->class && tp_event->class->reg &&
222 try_module_get(tp_event->mod)) {
223 ret = perf_trace_event_init(tp_event, p_event);
225 module_put(tp_event->mod);
229 mutex_unlock(&event_mutex);
234 void perf_trace_destroy(struct perf_event *p_event)
236 mutex_lock(&event_mutex);
237 perf_trace_event_close(p_event);
238 perf_trace_event_unreg(p_event);
239 mutex_unlock(&event_mutex);
242 #ifdef CONFIG_KPROBE_EVENTS
243 int perf_kprobe_init(struct perf_event *p_event, bool is_retprobe)
247 struct trace_event_call *tp_event;
249 if (p_event->attr.kprobe_func) {
250 func = kzalloc(KSYM_NAME_LEN, GFP_KERNEL);
253 ret = strncpy_from_user(
254 func, u64_to_user_ptr(p_event->attr.kprobe_func),
256 if (ret == KSYM_NAME_LEN)
261 if (func[0] == '\0') {
267 tp_event = create_local_trace_kprobe(
268 func, (void *)(unsigned long)(p_event->attr.kprobe_addr),
269 p_event->attr.probe_offset, is_retprobe);
270 if (IS_ERR(tp_event)) {
271 ret = PTR_ERR(tp_event);
275 ret = perf_trace_event_init(tp_event, p_event);
277 destroy_local_trace_kprobe(tp_event);
283 void perf_kprobe_destroy(struct perf_event *p_event)
285 perf_trace_event_close(p_event);
286 perf_trace_event_unreg(p_event);
288 destroy_local_trace_kprobe(p_event->tp_event);
290 #endif /* CONFIG_KPROBE_EVENTS */
292 #ifdef CONFIG_UPROBE_EVENTS
293 int perf_uprobe_init(struct perf_event *p_event, bool is_retprobe)
297 struct trace_event_call *tp_event;
299 if (!p_event->attr.uprobe_path)
301 path = kzalloc(PATH_MAX, GFP_KERNEL);
304 ret = strncpy_from_user(
305 path, u64_to_user_ptr(p_event->attr.uprobe_path), PATH_MAX);
310 if (path[0] == '\0') {
315 tp_event = create_local_trace_uprobe(
316 path, p_event->attr.probe_offset, is_retprobe);
317 if (IS_ERR(tp_event)) {
318 ret = PTR_ERR(tp_event);
323 * local trace_uprobe need to hold event_mutex to call
324 * uprobe_buffer_enable() and uprobe_buffer_disable().
325 * event_mutex is not required for local trace_kprobes.
327 mutex_lock(&event_mutex);
328 ret = perf_trace_event_init(tp_event, p_event);
330 destroy_local_trace_uprobe(tp_event);
331 mutex_unlock(&event_mutex);
337 void perf_uprobe_destroy(struct perf_event *p_event)
339 mutex_lock(&event_mutex);
340 perf_trace_event_close(p_event);
341 perf_trace_event_unreg(p_event);
342 mutex_unlock(&event_mutex);
343 destroy_local_trace_uprobe(p_event->tp_event);
345 #endif /* CONFIG_UPROBE_EVENTS */
347 int perf_trace_add(struct perf_event *p_event, int flags)
349 struct trace_event_call *tp_event = p_event->tp_event;
351 if (!(flags & PERF_EF_START))
352 p_event->hw.state = PERF_HES_STOPPED;
355 * If TRACE_REG_PERF_ADD returns false; no custom action was performed
356 * and we need to take the default action of enqueueing our event on
357 * the right per-cpu hlist.
359 if (!tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event)) {
360 struct hlist_head __percpu *pcpu_list;
361 struct hlist_head *list;
363 pcpu_list = tp_event->perf_events;
364 if (WARN_ON_ONCE(!pcpu_list))
367 list = this_cpu_ptr(pcpu_list);
368 hlist_add_head_rcu(&p_event->hlist_entry, list);
374 void perf_trace_del(struct perf_event *p_event, int flags)
376 struct trace_event_call *tp_event = p_event->tp_event;
379 * If TRACE_REG_PERF_DEL returns false; no custom action was performed
380 * and we need to take the default action of dequeueing our event from
381 * the right per-cpu hlist.
383 if (!tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event))
384 hlist_del_rcu(&p_event->hlist_entry);
387 void *perf_trace_buf_alloc(int size, struct pt_regs **regs, int *rctxp)
392 BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
394 if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
395 "perf buffer not large enough"))
398 *rctxp = rctx = perf_swevent_get_recursion_context();
403 *regs = this_cpu_ptr(&__perf_regs[rctx]);
404 raw_data = this_cpu_ptr(perf_trace_buf[rctx]);
406 /* zero the dead bytes from align to not leak stack to user */
407 memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
410 EXPORT_SYMBOL_GPL(perf_trace_buf_alloc);
411 NOKPROBE_SYMBOL(perf_trace_buf_alloc);
413 void perf_trace_buf_update(void *record, u16 type)
415 struct trace_entry *entry = record;
416 int pc = preempt_count();
419 local_save_flags(flags);
420 tracing_generic_entry_update(entry, flags, pc);
423 NOKPROBE_SYMBOL(perf_trace_buf_update);
425 #ifdef CONFIG_FUNCTION_TRACER
427 perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
428 struct ftrace_ops *ops, struct pt_regs *pt_regs)
430 struct ftrace_entry *entry;
431 struct perf_event *event;
432 struct hlist_head head;
436 if ((unsigned long)ops->private != smp_processor_id())
439 event = container_of(ops, struct perf_event, ftrace_ops);
442 * @event->hlist entry is NULL (per INIT_HLIST_NODE), and all
443 * the perf code does is hlist_for_each_entry_rcu(), so we can
444 * get away with simply setting the @head.first pointer in order
445 * to create a singular list.
447 head.first = &event->hlist_entry;
449 #define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
450 sizeof(u64)) - sizeof(u32))
452 BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);
454 memset(®s, 0, sizeof(regs));
455 perf_fetch_caller_regs(®s);
457 entry = perf_trace_buf_alloc(ENTRY_SIZE, NULL, &rctx);
462 entry->parent_ip = parent_ip;
463 perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, TRACE_FN,
464 1, ®s, &head, NULL);
469 static int perf_ftrace_function_register(struct perf_event *event)
471 struct ftrace_ops *ops = &event->ftrace_ops;
473 ops->flags = FTRACE_OPS_FL_RCU;
474 ops->func = perf_ftrace_function_call;
475 ops->private = (void *)(unsigned long)nr_cpu_ids;
477 return register_ftrace_function(ops);
480 static int perf_ftrace_function_unregister(struct perf_event *event)
482 struct ftrace_ops *ops = &event->ftrace_ops;
483 int ret = unregister_ftrace_function(ops);
484 ftrace_free_filter(ops);
488 int perf_ftrace_event_register(struct trace_event_call *call,
489 enum trace_reg type, void *data)
491 struct perf_event *event = data;
494 case TRACE_REG_REGISTER:
495 case TRACE_REG_UNREGISTER:
497 case TRACE_REG_PERF_REGISTER:
498 case TRACE_REG_PERF_UNREGISTER:
500 case TRACE_REG_PERF_OPEN:
501 return perf_ftrace_function_register(data);
502 case TRACE_REG_PERF_CLOSE:
503 return perf_ftrace_function_unregister(data);
504 case TRACE_REG_PERF_ADD:
505 event->ftrace_ops.private = (void *)(unsigned long)smp_processor_id();
507 case TRACE_REG_PERF_DEL:
508 event->ftrace_ops.private = (void *)(unsigned long)nr_cpu_ids;
514 #endif /* CONFIG_FUNCTION_TRACER */