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(&regs, 0, sizeof(regs));
324	perf_fetch_caller_regs(&regs);
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, &regs, 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 */

  1/*
  2 * trace event based perf event profiling/tracing
  3 *
  4 * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
  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 ftrace_event_call *tp_event,
 25				 struct perf_event *p_event)
 26{
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 27	/* The ftrace function trace is allowed only for root. */
 28	if (ftrace_event_is_function(tp_event) &&
 29	    perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
 30		return -EPERM;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 31
 32	/* No tracing, just counting, so no obvious leak */
 33	if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
 34		return 0;
 35
 36	/* Some events are ok to be traced by non-root users... */
 37	if (p_event->attach_state == PERF_ATTACH_TASK) {
 38		if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY)
 39			return 0;
 40	}
 41
 42	/*
 43	 * ...otherwise raw tracepoint data can be a severe data leak,
 44	 * only allow root to have these.
 45	 */
 46	if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
 47		return -EPERM;
 48
 49	return 0;
 50}
 51
 52static int perf_trace_event_reg(struct ftrace_event_call *tp_event,
 53				struct perf_event *p_event)
 54{
 55	struct hlist_head __percpu *list;
 56	int ret = -ENOMEM;
 57	int cpu;
 58
 59	p_event->tp_event = tp_event;
 60	if (tp_event->perf_refcount++ > 0)
 61		return 0;
 62
 63	list = alloc_percpu(struct hlist_head);
 64	if (!list)
 65		goto fail;
 66
 67	for_each_possible_cpu(cpu)
 68		INIT_HLIST_HEAD(per_cpu_ptr(list, cpu));
 69
 70	tp_event->perf_events = list;
 71
 72	if (!total_ref_count) {
 73		char __percpu *buf;
 74		int i;
 75
 76		for (i = 0; i < PERF_NR_CONTEXTS; i++) {
 77			buf = (char __percpu *)alloc_percpu(perf_trace_t);
 78			if (!buf)
 79				goto fail;
 80
 81			perf_trace_buf[i] = buf;
 82		}
 83	}
 84
 85	ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL);
 86	if (ret)
 87		goto fail;
 88
 89	total_ref_count++;
 90	return 0;
 91
 92fail:
 93	if (!total_ref_count) {
 94		int i;
 95
 96		for (i = 0; i < PERF_NR_CONTEXTS; i++) {
 97			free_percpu(perf_trace_buf[i]);
 98			perf_trace_buf[i] = NULL;
 99		}
100	}
101
102	if (!--tp_event->perf_refcount) {
103		free_percpu(tp_event->perf_events);
104		tp_event->perf_events = NULL;
105	}
106
107	return ret;
108}
109
110static void perf_trace_event_unreg(struct perf_event *p_event)
111{
112	struct ftrace_event_call *tp_event = p_event->tp_event;
113	int i;
114
115	if (--tp_event->perf_refcount > 0)
116		goto out;
117
118	tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL);
119
120	/*
121	 * Ensure our callback won't be called anymore. The buffers
122	 * will be freed after that.
123	 */
124	tracepoint_synchronize_unregister();
125
126	free_percpu(tp_event->perf_events);
127	tp_event->perf_events = NULL;
128
129	if (!--total_ref_count) {
130		for (i = 0; i < PERF_NR_CONTEXTS; i++) {
131			free_percpu(perf_trace_buf[i]);
132			perf_trace_buf[i] = NULL;
133		}
134	}
135out:
136	module_put(tp_event->mod);
137}
138
139static int perf_trace_event_open(struct perf_event *p_event)
140{
141	struct ftrace_event_call *tp_event = p_event->tp_event;
142	return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event);
143}
144
145static void perf_trace_event_close(struct perf_event *p_event)
146{
147	struct ftrace_event_call *tp_event = p_event->tp_event;
148	tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);
149}
150
151static int perf_trace_event_init(struct ftrace_event_call *tp_event,
152				 struct perf_event *p_event)
153{
154	int ret;
155
156	ret = perf_trace_event_perm(tp_event, p_event);
157	if (ret)
158		return ret;
159
160	ret = perf_trace_event_reg(tp_event, p_event);
161	if (ret)
162		return ret;
163
164	ret = perf_trace_event_open(p_event);
165	if (ret) {
166		perf_trace_event_unreg(p_event);
167		return ret;
168	}
169
170	return 0;
171}
172
173int perf_trace_init(struct perf_event *p_event)
174{
175	struct ftrace_event_call *tp_event;
176	int event_id = p_event->attr.config;
177	int ret = -EINVAL;
178
179	mutex_lock(&event_mutex);
180	list_for_each_entry(tp_event, &ftrace_events, list) {
181		if (tp_event->event.type == event_id &&
182		    tp_event->class && tp_event->class->reg &&
183		    try_module_get(tp_event->mod)) {
184			ret = perf_trace_event_init(tp_event, p_event);
185			if (ret)
186				module_put(tp_event->mod);
187			break;
188		}
189	}
190	mutex_unlock(&event_mutex);
191
192	return ret;
193}
194
195void perf_trace_destroy(struct perf_event *p_event)
196{
197	mutex_lock(&event_mutex);
198	perf_trace_event_close(p_event);
199	perf_trace_event_unreg(p_event);
200	mutex_unlock(&event_mutex);
201}
202
203int perf_trace_add(struct perf_event *p_event, int flags)
204{
205	struct ftrace_event_call *tp_event = p_event->tp_event;
206	struct hlist_head __percpu *pcpu_list;
207	struct hlist_head *list;
208
209	pcpu_list = tp_event->perf_events;
210	if (WARN_ON_ONCE(!pcpu_list))
211		return -EINVAL;
212
213	if (!(flags & PERF_EF_START))
214		p_event->hw.state = PERF_HES_STOPPED;
215
216	list = this_cpu_ptr(pcpu_list);
217	hlist_add_head_rcu(&p_event->hlist_entry, list);
218
219	return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event);
220}
221
222void perf_trace_del(struct perf_event *p_event, int flags)
223{
224	struct ftrace_event_call *tp_event = p_event->tp_event;
225	hlist_del_rcu(&p_event->hlist_entry);
226	tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event);
227}
228
229__kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
230				       struct pt_regs *regs, int *rctxp)
231{
232	struct trace_entry *entry;
233	unsigned long flags;
234	char *raw_data;
235	int pc;
236
237	BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
238
239	pc = preempt_count();
 
 
240
241	*rctxp = perf_swevent_get_recursion_context();
242	if (*rctxp < 0)
243		return NULL;
244
245	raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]);
 
 
246
247	/* zero the dead bytes from align to not leak stack to user */
248	memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
 
 
 
 
 
 
 
 
 
 
249
250	entry = (struct trace_entry *)raw_data;
251	local_save_flags(flags);
252	tracing_generic_entry_update(entry, flags, pc);
253	entry->type = type;
254
255	return raw_data;
256}
257EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
258
259#ifdef CONFIG_FUNCTION_TRACER
260static void
261perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip)
 
262{
263	struct ftrace_entry *entry;
264	struct hlist_head *head;
265	struct pt_regs regs;
266	int rctx;
267
 
 
 
 
268#define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
269		    sizeof(u64)) - sizeof(u32))
270
271	BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);
272
 
273	perf_fetch_caller_regs(&regs);
274
275	entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx);
276	if (!entry)
277		return;
278
279	entry->ip = ip;
280	entry->parent_ip = parent_ip;
281
282	head = this_cpu_ptr(event_function.perf_events);
283	perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
284			      1, &regs, head);
285
286#undef ENTRY_SIZE
287}
288
289static int perf_ftrace_function_register(struct perf_event *event)
290{
291	struct ftrace_ops *ops = &event->ftrace_ops;
292
293	ops->flags |= FTRACE_OPS_FL_CONTROL;
294	ops->func = perf_ftrace_function_call;
295	return register_ftrace_function(ops);
296}
297
298static int perf_ftrace_function_unregister(struct perf_event *event)
299{
300	struct ftrace_ops *ops = &event->ftrace_ops;
301	int ret = unregister_ftrace_function(ops);
302	ftrace_free_filter(ops);
303	return ret;
304}
305
306static void perf_ftrace_function_enable(struct perf_event *event)
307{
308	ftrace_function_local_enable(&event->ftrace_ops);
309}
310
311static void perf_ftrace_function_disable(struct perf_event *event)
312{
313	ftrace_function_local_disable(&event->ftrace_ops);
314}
315
316int perf_ftrace_event_register(struct ftrace_event_call *call,
317			       enum trace_reg type, void *data)
318{
319	switch (type) {
320	case TRACE_REG_REGISTER:
321	case TRACE_REG_UNREGISTER:
322		break;
323	case TRACE_REG_PERF_REGISTER:
324	case TRACE_REG_PERF_UNREGISTER:
325		return 0;
326	case TRACE_REG_PERF_OPEN:
327		return perf_ftrace_function_register(data);
328	case TRACE_REG_PERF_CLOSE:
329		return perf_ftrace_function_unregister(data);
330	case TRACE_REG_PERF_ADD:
331		perf_ftrace_function_enable(data);
332		return 0;
333	case TRACE_REG_PERF_DEL:
334		perf_ftrace_function_disable(data);
335		return 0;
336	}
337
338	return -EINVAL;
339}
340#endif /* CONFIG_FUNCTION_TRACER */