Linux 3.8-rc7
[cris-mirror.git] / kernel / trace / trace_event_perf.c
blob84b1e045faba836583fb371d285f49e79bfa6bd0
1 /*
2 * trace event based perf event profiling/tracing
4 * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
5 * Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com>
6 */
8 #include <linux/module.h>
9 #include <linux/kprobes.h>
10 #include "trace.h"
12 static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS];
15 * Force it to be aligned to unsigned long to avoid misaligned accesses
16 * suprises
18 typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
19 perf_trace_t;
21 /* Count the events in use (per event id, not per instance) */
22 static int total_ref_count;
24 static int perf_trace_event_perm(struct ftrace_event_call *tp_event,
25 struct perf_event *p_event)
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;
32 /* No tracing, just counting, so no obvious leak */
33 if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
34 return 0;
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;
43 * ...otherwise raw tracepoint data can be a severe data leak,
44 * only allow root to have these.
46 if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
47 return -EPERM;
49 return 0;
52 static int perf_trace_event_reg(struct ftrace_event_call *tp_event,
53 struct perf_event *p_event)
55 struct hlist_head __percpu *list;
56 int ret = -ENOMEM;
57 int cpu;
59 p_event->tp_event = tp_event;
60 if (tp_event->perf_refcount++ > 0)
61 return 0;
63 list = alloc_percpu(struct hlist_head);
64 if (!list)
65 goto fail;
67 for_each_possible_cpu(cpu)
68 INIT_HLIST_HEAD(per_cpu_ptr(list, cpu));
70 tp_event->perf_events = list;
72 if (!total_ref_count) {
73 char __percpu *buf;
74 int i;
76 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
77 buf = (char __percpu *)alloc_percpu(perf_trace_t);
78 if (!buf)
79 goto fail;
81 perf_trace_buf[i] = buf;
85 ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL);
86 if (ret)
87 goto fail;
89 total_ref_count++;
90 return 0;
92 fail:
93 if (!total_ref_count) {
94 int i;
96 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
97 free_percpu(perf_trace_buf[i]);
98 perf_trace_buf[i] = NULL;
102 if (!--tp_event->perf_refcount) {
103 free_percpu(tp_event->perf_events);
104 tp_event->perf_events = NULL;
107 return ret;
110 static void perf_trace_event_unreg(struct perf_event *p_event)
112 struct ftrace_event_call *tp_event = p_event->tp_event;
113 int i;
115 if (--tp_event->perf_refcount > 0)
116 goto out;
118 tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL);
121 * Ensure our callback won't be called anymore. The buffers
122 * will be freed after that.
124 tracepoint_synchronize_unregister();
126 free_percpu(tp_event->perf_events);
127 tp_event->perf_events = NULL;
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;
135 out:
136 module_put(tp_event->mod);
139 static int perf_trace_event_open(struct perf_event *p_event)
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);
145 static void perf_trace_event_close(struct perf_event *p_event)
147 struct ftrace_event_call *tp_event = p_event->tp_event;
148 tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);
151 static int perf_trace_event_init(struct ftrace_event_call *tp_event,
152 struct perf_event *p_event)
154 int ret;
156 ret = perf_trace_event_perm(tp_event, p_event);
157 if (ret)
158 return ret;
160 ret = perf_trace_event_reg(tp_event, p_event);
161 if (ret)
162 return ret;
164 ret = perf_trace_event_open(p_event);
165 if (ret) {
166 perf_trace_event_unreg(p_event);
167 return ret;
170 return 0;
173 int perf_trace_init(struct perf_event *p_event)
175 struct ftrace_event_call *tp_event;
176 int event_id = p_event->attr.config;
177 int ret = -EINVAL;
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;
190 mutex_unlock(&event_mutex);
192 return ret;
195 void perf_trace_destroy(struct perf_event *p_event)
197 mutex_lock(&event_mutex);
198 perf_trace_event_close(p_event);
199 perf_trace_event_unreg(p_event);
200 mutex_unlock(&event_mutex);
203 int perf_trace_add(struct perf_event *p_event, int flags)
205 struct ftrace_event_call *tp_event = p_event->tp_event;
206 struct hlist_head __percpu *pcpu_list;
207 struct hlist_head *list;
209 pcpu_list = tp_event->perf_events;
210 if (WARN_ON_ONCE(!pcpu_list))
211 return -EINVAL;
213 if (!(flags & PERF_EF_START))
214 p_event->hw.state = PERF_HES_STOPPED;
216 list = this_cpu_ptr(pcpu_list);
217 hlist_add_head_rcu(&p_event->hlist_entry, list);
219 return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event);
222 void perf_trace_del(struct perf_event *p_event, int flags)
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);
229 __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
230 struct pt_regs *regs, int *rctxp)
232 struct trace_entry *entry;
233 unsigned long flags;
234 char *raw_data;
235 int pc;
237 BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
239 pc = preempt_count();
241 *rctxp = perf_swevent_get_recursion_context();
242 if (*rctxp < 0)
243 return NULL;
245 raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]);
247 /* zero the dead bytes from align to not leak stack to user */
248 memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
250 entry = (struct trace_entry *)raw_data;
251 local_save_flags(flags);
252 tracing_generic_entry_update(entry, flags, pc);
253 entry->type = type;
255 return raw_data;
257 EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
259 #ifdef CONFIG_FUNCTION_TRACER
260 static void
261 perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
262 struct ftrace_ops *ops, struct pt_regs *pt_regs)
264 struct ftrace_entry *entry;
265 struct hlist_head *head;
266 struct pt_regs regs;
267 int rctx;
269 #define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
270 sizeof(u64)) - sizeof(u32))
272 BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);
274 perf_fetch_caller_regs(&regs);
276 entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx);
277 if (!entry)
278 return;
280 entry->ip = ip;
281 entry->parent_ip = parent_ip;
283 head = this_cpu_ptr(event_function.perf_events);
284 perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
285 1, &regs, head, NULL);
287 #undef ENTRY_SIZE
290 static int perf_ftrace_function_register(struct perf_event *event)
292 struct ftrace_ops *ops = &event->ftrace_ops;
294 ops->flags |= FTRACE_OPS_FL_CONTROL;
295 ops->func = perf_ftrace_function_call;
296 return register_ftrace_function(ops);
299 static int perf_ftrace_function_unregister(struct perf_event *event)
301 struct ftrace_ops *ops = &event->ftrace_ops;
302 int ret = unregister_ftrace_function(ops);
303 ftrace_free_filter(ops);
304 return ret;
307 static void perf_ftrace_function_enable(struct perf_event *event)
309 ftrace_function_local_enable(&event->ftrace_ops);
312 static void perf_ftrace_function_disable(struct perf_event *event)
314 ftrace_function_local_disable(&event->ftrace_ops);
317 int perf_ftrace_event_register(struct ftrace_event_call *call,
318 enum trace_reg type, void *data)
320 switch (type) {
321 case TRACE_REG_REGISTER:
322 case TRACE_REG_UNREGISTER:
323 break;
324 case TRACE_REG_PERF_REGISTER:
325 case TRACE_REG_PERF_UNREGISTER:
326 return 0;
327 case TRACE_REG_PERF_OPEN:
328 return perf_ftrace_function_register(data);
329 case TRACE_REG_PERF_CLOSE:
330 return perf_ftrace_function_unregister(data);
331 case TRACE_REG_PERF_ADD:
332 perf_ftrace_function_enable(data);
333 return 0;
334 case TRACE_REG_PERF_DEL:
335 perf_ftrace_function_disable(data);
336 return 0;
339 return -EINVAL;
341 #endif /* CONFIG_FUNCTION_TRACER */