Merge branch 'pm-cpufreq'
[cascardo/linux.git] / kernel / trace / trace_event_perf.c
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
12 static 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  */
18 typedef 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) */
22 static int      total_ref_count;
23
24 static int perf_trace_event_perm(struct ftrace_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         /* The ftrace function trace is allowed only for root. */
34         if (ftrace_event_is_function(tp_event)) {
35                 if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
36                         return -EPERM;
37
38                 /*
39                  * We don't allow user space callchains for  function trace
40                  * event, due to issues with page faults while tracing page
41                  * fault handler and its overall trickiness nature.
42                  */
43                 if (!p_event->attr.exclude_callchain_user)
44                         return -EINVAL;
45
46                 /*
47                  * Same reason to disable user stack dump as for user space
48                  * callchains above.
49                  */
50                 if (p_event->attr.sample_type & PERF_SAMPLE_STACK_USER)
51                         return -EINVAL;
52         }
53
54         /* No tracing, just counting, so no obvious leak */
55         if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
56                 return 0;
57
58         /* Some events are ok to be traced by non-root users... */
59         if (p_event->attach_state == PERF_ATTACH_TASK) {
60                 if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY)
61                         return 0;
62         }
63
64         /*
65          * ...otherwise raw tracepoint data can be a severe data leak,
66          * only allow root to have these.
67          */
68         if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
69                 return -EPERM;
70
71         return 0;
72 }
73
74 static int perf_trace_event_reg(struct ftrace_event_call *tp_event,
75                                 struct perf_event *p_event)
76 {
77         struct hlist_head __percpu *list;
78         int ret = -ENOMEM;
79         int cpu;
80
81         p_event->tp_event = tp_event;
82         if (tp_event->perf_refcount++ > 0)
83                 return 0;
84
85         list = alloc_percpu(struct hlist_head);
86         if (!list)
87                 goto fail;
88
89         for_each_possible_cpu(cpu)
90                 INIT_HLIST_HEAD(per_cpu_ptr(list, cpu));
91
92         tp_event->perf_events = list;
93
94         if (!total_ref_count) {
95                 char __percpu *buf;
96                 int i;
97
98                 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
99                         buf = (char __percpu *)alloc_percpu(perf_trace_t);
100                         if (!buf)
101                                 goto fail;
102
103                         perf_trace_buf[i] = buf;
104                 }
105         }
106
107         ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL);
108         if (ret)
109                 goto fail;
110
111         total_ref_count++;
112         return 0;
113
114 fail:
115         if (!total_ref_count) {
116                 int i;
117
118                 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
119                         free_percpu(perf_trace_buf[i]);
120                         perf_trace_buf[i] = NULL;
121                 }
122         }
123
124         if (!--tp_event->perf_refcount) {
125                 free_percpu(tp_event->perf_events);
126                 tp_event->perf_events = NULL;
127         }
128
129         return ret;
130 }
131
132 static void perf_trace_event_unreg(struct perf_event *p_event)
133 {
134         struct ftrace_event_call *tp_event = p_event->tp_event;
135         int i;
136
137         if (--tp_event->perf_refcount > 0)
138                 goto out;
139
140         tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL);
141
142         /*
143          * Ensure our callback won't be called anymore. The buffers
144          * will be freed after that.
145          */
146         tracepoint_synchronize_unregister();
147
148         free_percpu(tp_event->perf_events);
149         tp_event->perf_events = NULL;
150
151         if (!--total_ref_count) {
152                 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
153                         free_percpu(perf_trace_buf[i]);
154                         perf_trace_buf[i] = NULL;
155                 }
156         }
157 out:
158         module_put(tp_event->mod);
159 }
160
161 static int perf_trace_event_open(struct perf_event *p_event)
162 {
163         struct ftrace_event_call *tp_event = p_event->tp_event;
164         return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event);
165 }
166
167 static void perf_trace_event_close(struct perf_event *p_event)
168 {
169         struct ftrace_event_call *tp_event = p_event->tp_event;
170         tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);
171 }
172
173 static int perf_trace_event_init(struct ftrace_event_call *tp_event,
174                                  struct perf_event *p_event)
175 {
176         int ret;
177
178         ret = perf_trace_event_perm(tp_event, p_event);
179         if (ret)
180                 return ret;
181
182         ret = perf_trace_event_reg(tp_event, p_event);
183         if (ret)
184                 return ret;
185
186         ret = perf_trace_event_open(p_event);
187         if (ret) {
188                 perf_trace_event_unreg(p_event);
189                 return ret;
190         }
191
192         return 0;
193 }
194
195 int perf_trace_init(struct perf_event *p_event)
196 {
197         struct ftrace_event_call *tp_event;
198         u64 event_id = p_event->attr.config;
199         int ret = -EINVAL;
200
201         mutex_lock(&event_mutex);
202         list_for_each_entry(tp_event, &ftrace_events, list) {
203                 if (tp_event->event.type == event_id &&
204                     tp_event->class && tp_event->class->reg &&
205                     try_module_get(tp_event->mod)) {
206                         ret = perf_trace_event_init(tp_event, p_event);
207                         if (ret)
208                                 module_put(tp_event->mod);
209                         break;
210                 }
211         }
212         mutex_unlock(&event_mutex);
213
214         return ret;
215 }
216
217 void perf_trace_destroy(struct perf_event *p_event)
218 {
219         mutex_lock(&event_mutex);
220         perf_trace_event_close(p_event);
221         perf_trace_event_unreg(p_event);
222         mutex_unlock(&event_mutex);
223 }
224
225 int perf_trace_add(struct perf_event *p_event, int flags)
226 {
227         struct ftrace_event_call *tp_event = p_event->tp_event;
228         struct hlist_head __percpu *pcpu_list;
229         struct hlist_head *list;
230
231         pcpu_list = tp_event->perf_events;
232         if (WARN_ON_ONCE(!pcpu_list))
233                 return -EINVAL;
234
235         if (!(flags & PERF_EF_START))
236                 p_event->hw.state = PERF_HES_STOPPED;
237
238         list = this_cpu_ptr(pcpu_list);
239         hlist_add_head_rcu(&p_event->hlist_entry, list);
240
241         return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event);
242 }
243
244 void perf_trace_del(struct perf_event *p_event, int flags)
245 {
246         struct ftrace_event_call *tp_event = p_event->tp_event;
247         hlist_del_rcu(&p_event->hlist_entry);
248         tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event);
249 }
250
251 __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
252                                        struct pt_regs *regs, int *rctxp)
253 {
254         struct trace_entry *entry;
255         unsigned long flags;
256         char *raw_data;
257         int pc;
258
259         BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
260
261         if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
262                         "perf buffer not large enough"))
263                 return NULL;
264
265         pc = preempt_count();
266
267         *rctxp = perf_swevent_get_recursion_context();
268         if (*rctxp < 0)
269                 return NULL;
270
271         raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]);
272
273         /* zero the dead bytes from align to not leak stack to user */
274         memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
275
276         entry = (struct trace_entry *)raw_data;
277         local_save_flags(flags);
278         tracing_generic_entry_update(entry, flags, pc);
279         entry->type = type;
280
281         return raw_data;
282 }
283 EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
284
285 #ifdef CONFIG_FUNCTION_TRACER
286 static void
287 perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
288                           struct ftrace_ops *ops, struct pt_regs *pt_regs)
289 {
290         struct ftrace_entry *entry;
291         struct hlist_head *head;
292         struct pt_regs regs;
293         int rctx;
294
295         head = this_cpu_ptr(event_function.perf_events);
296         if (hlist_empty(head))
297                 return;
298
299 #define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
300                     sizeof(u64)) - sizeof(u32))
301
302         BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);
303
304         perf_fetch_caller_regs(&regs);
305
306         entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx);
307         if (!entry)
308                 return;
309
310         entry->ip = ip;
311         entry->parent_ip = parent_ip;
312         perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
313                               1, &regs, head, NULL);
314
315 #undef ENTRY_SIZE
316 }
317
318 static int perf_ftrace_function_register(struct perf_event *event)
319 {
320         struct ftrace_ops *ops = &event->ftrace_ops;
321
322         ops->flags |= FTRACE_OPS_FL_CONTROL;
323         ops->func = perf_ftrace_function_call;
324         return register_ftrace_function(ops);
325 }
326
327 static int perf_ftrace_function_unregister(struct perf_event *event)
328 {
329         struct ftrace_ops *ops = &event->ftrace_ops;
330         int ret = unregister_ftrace_function(ops);
331         ftrace_free_filter(ops);
332         return ret;
333 }
334
335 static void perf_ftrace_function_enable(struct perf_event *event)
336 {
337         ftrace_function_local_enable(&event->ftrace_ops);
338 }
339
340 static void perf_ftrace_function_disable(struct perf_event *event)
341 {
342         ftrace_function_local_disable(&event->ftrace_ops);
343 }
344
345 int perf_ftrace_event_register(struct ftrace_event_call *call,
346                                enum trace_reg type, void *data)
347 {
348         switch (type) {
349         case TRACE_REG_REGISTER:
350         case TRACE_REG_UNREGISTER:
351                 break;
352         case TRACE_REG_PERF_REGISTER:
353         case TRACE_REG_PERF_UNREGISTER:
354                 return 0;
355         case TRACE_REG_PERF_OPEN:
356                 return perf_ftrace_function_register(data);
357         case TRACE_REG_PERF_CLOSE:
358                 return perf_ftrace_function_unregister(data);
359         case TRACE_REG_PERF_ADD:
360                 perf_ftrace_function_enable(data);
361                 return 0;
362         case TRACE_REG_PERF_DEL:
363                 perf_ftrace_function_disable(data);
364                 return 0;
365         }
366
367         return -EINVAL;
368 }
369 #endif /* CONFIG_FUNCTION_TRACER */