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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
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 /*
51 * We don't allow user space callchains for function trace
52 * event, due to issues with page faults while tracing page
53 * fault handler and its overall trickiness nature.
54 */
55 if (!p_event->attr.exclude_callchain_user)
56 return -EINVAL;
57
58 /*
59 * Same reason to disable user stack dump as for user space
60 * callchains above.
61 */
62 if (p_event->attr.sample_type & PERF_SAMPLE_STACK_USER)
63 return -EINVAL;
64 }
65
66 /* No tracing, just counting, so no obvious leak */
67 if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
68 return 0;
69
70 /* Some events are ok to be traced by non-root users... */
71 if (p_event->attach_state == PERF_ATTACH_TASK) {
72 if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY)
73 return 0;
74 }
75
76 /*
77 * ...otherwise raw tracepoint data can be a severe data leak,
78 * only allow root to have these.
79 */
80 if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
81 return -EPERM;
82
83 return 0;
84}
85
86static int perf_trace_event_reg(struct trace_event_call *tp_event,
87 struct perf_event *p_event)
88{
89 struct hlist_head __percpu *list;
90 int ret = -ENOMEM;
91 int cpu;
92
93 p_event->tp_event = tp_event;
94 if (tp_event->perf_refcount++ > 0)
95 return 0;
96
97 list = alloc_percpu(struct hlist_head);
98 if (!list)
99 goto fail;
100
101 for_each_possible_cpu(cpu)
102 INIT_HLIST_HEAD(per_cpu_ptr(list, cpu));
103
104 tp_event->perf_events = list;
105
106 if (!total_ref_count) {
107 char __percpu *buf;
108 int i;
109
110 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
111 buf = (char __percpu *)alloc_percpu(perf_trace_t);
112 if (!buf)
113 goto fail;
114
115 perf_trace_buf[i] = buf;
116 }
117 }
118
119 ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL);
120 if (ret)
121 goto fail;
122
123 total_ref_count++;
124 return 0;
125
126fail:
127 if (!total_ref_count) {
128 int i;
129
130 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
131 free_percpu(perf_trace_buf[i]);
132 perf_trace_buf[i] = NULL;
133 }
134 }
135
136 if (!--tp_event->perf_refcount) {
137 free_percpu(tp_event->perf_events);
138 tp_event->perf_events = NULL;
139 }
140
141 return ret;
142}
143
144static void perf_trace_event_unreg(struct perf_event *p_event)
145{
146 struct trace_event_call *tp_event = p_event->tp_event;
147 int i;
148
149 if (--tp_event->perf_refcount > 0)
150 goto out;
151
152 tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL);
153
154 /*
155 * Ensure our callback won't be called anymore. The buffers
156 * will be freed after that.
157 */
158 tracepoint_synchronize_unregister();
159
160 free_percpu(tp_event->perf_events);
161 tp_event->perf_events = NULL;
162
163 if (!--total_ref_count) {
164 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
165 free_percpu(perf_trace_buf[i]);
166 perf_trace_buf[i] = NULL;
167 }
168 }
169out:
170 module_put(tp_event->mod);
171}
172
173static int perf_trace_event_open(struct perf_event *p_event)
174{
175 struct trace_event_call *tp_event = p_event->tp_event;
176 return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event);
177}
178
179static void perf_trace_event_close(struct perf_event *p_event)
180{
181 struct trace_event_call *tp_event = p_event->tp_event;
182 tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);
183}
184
185static int perf_trace_event_init(struct trace_event_call *tp_event,
186 struct perf_event *p_event)
187{
188 int ret;
189
190 ret = perf_trace_event_perm(tp_event, p_event);
191 if (ret)
192 return ret;
193
194 ret = perf_trace_event_reg(tp_event, p_event);
195 if (ret)
196 return ret;
197
198 ret = perf_trace_event_open(p_event);
199 if (ret) {
200 perf_trace_event_unreg(p_event);
201 return ret;
202 }
203
204 return 0;
205}
206
207int perf_trace_init(struct perf_event *p_event)
208{
209 struct trace_event_call *tp_event;
210 u64 event_id = p_event->attr.config;
211 int ret = -EINVAL;
212
213 mutex_lock(&event_mutex);
214 list_for_each_entry(tp_event, &ftrace_events, list) {
215 if (tp_event->event.type == event_id &&
216 tp_event->class && tp_event->class->reg &&
217 try_module_get(tp_event->mod)) {
218 ret = perf_trace_event_init(tp_event, p_event);
219 if (ret)
220 module_put(tp_event->mod);
221 break;
222 }
223 }
224 mutex_unlock(&event_mutex);
225
226 return ret;
227}
228
229void perf_trace_destroy(struct perf_event *p_event)
230{
231 mutex_lock(&event_mutex);
232 perf_trace_event_close(p_event);
233 perf_trace_event_unreg(p_event);
234 mutex_unlock(&event_mutex);
235}
236
237int perf_trace_add(struct perf_event *p_event, int flags)
238{
239 struct trace_event_call *tp_event = p_event->tp_event;
240 struct hlist_head __percpu *pcpu_list;
241 struct hlist_head *list;
242
243 pcpu_list = tp_event->perf_events;
244 if (WARN_ON_ONCE(!pcpu_list))
245 return -EINVAL;
246
247 if (!(flags & PERF_EF_START))
248 p_event->hw.state = PERF_HES_STOPPED;
249
250 list = this_cpu_ptr(pcpu_list);
251 hlist_add_head_rcu(&p_event->hlist_entry, list);
252
253 return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event);
254}
255
256void perf_trace_del(struct perf_event *p_event, int flags)
257{
258 struct trace_event_call *tp_event = p_event->tp_event;
259 hlist_del_rcu(&p_event->hlist_entry);
260 tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event);
261}
262
263void *perf_trace_buf_prepare(int size, unsigned short type,
264 struct pt_regs **regs, int *rctxp)
265{
266 struct trace_entry *entry;
267 unsigned long flags;
268 char *raw_data;
269 int pc;
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 pc = preempt_count();
278
279 *rctxp = perf_swevent_get_recursion_context();
280 if (*rctxp < 0)
281 return NULL;
282
283 if (regs)
284 *regs = this_cpu_ptr(&__perf_regs[*rctxp]);
285 raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]);
286
287 /* zero the dead bytes from align to not leak stack to user */
288 memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
289
290 entry = (struct trace_entry *)raw_data;
291 local_save_flags(flags);
292 tracing_generic_entry_update(entry, flags, pc);
293 entry->type = type;
294
295 return raw_data;
296}
297EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
298NOKPROBE_SYMBOL(perf_trace_buf_prepare);
299
300#ifdef CONFIG_FUNCTION_TRACER
301static void
302perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
303 struct ftrace_ops *ops, struct pt_regs *pt_regs)
304{
305 struct ftrace_entry *entry;
306 struct hlist_head *head;
307 struct pt_regs regs;
308 int rctx;
309
310 head = this_cpu_ptr(event_function.perf_events);
311 if (hlist_empty(head))
312 return;
313
314#define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
315 sizeof(u64)) - sizeof(u32))
316
317 BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);
318
319 perf_fetch_caller_regs(®s);
320
321 entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx);
322 if (!entry)
323 return;
324
325 entry->ip = ip;
326 entry->parent_ip = parent_ip;
327 perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
328 1, ®s, head, NULL);
329
330#undef ENTRY_SIZE
331}
332
333static int perf_ftrace_function_register(struct perf_event *event)
334{
335 struct ftrace_ops *ops = &event->ftrace_ops;
336
337 ops->flags |= FTRACE_OPS_FL_PER_CPU | FTRACE_OPS_FL_RCU;
338 ops->func = perf_ftrace_function_call;
339 return register_ftrace_function(ops);
340}
341
342static int perf_ftrace_function_unregister(struct perf_event *event)
343{
344 struct ftrace_ops *ops = &event->ftrace_ops;
345 int ret = unregister_ftrace_function(ops);
346 ftrace_free_filter(ops);
347 return ret;
348}
349
350static void perf_ftrace_function_enable(struct perf_event *event)
351{
352 ftrace_function_local_enable(&event->ftrace_ops);
353}
354
355static void perf_ftrace_function_disable(struct perf_event *event)
356{
357 ftrace_function_local_disable(&event->ftrace_ops);
358}
359
360int perf_ftrace_event_register(struct trace_event_call *call,
361 enum trace_reg type, void *data)
362{
363 switch (type) {
364 case TRACE_REG_REGISTER:
365 case TRACE_REG_UNREGISTER:
366 break;
367 case TRACE_REG_PERF_REGISTER:
368 case TRACE_REG_PERF_UNREGISTER:
369 return 0;
370 case TRACE_REG_PERF_OPEN:
371 return perf_ftrace_function_register(data);
372 case TRACE_REG_PERF_CLOSE:
373 return perf_ftrace_function_unregister(data);
374 case TRACE_REG_PERF_ADD:
375 perf_ftrace_function_enable(data);
376 return 0;
377 case TRACE_REG_PERF_DEL:
378 perf_ftrace_function_disable(data);
379 return 0;
380 }
381
382 return -EINVAL;
383}
384#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(®s);
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, ®s, 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 */