Commit | Line | Data |
---|---|---|
ac199db0 | 1 | /* |
97d5a220 | 2 | * trace event based perf event profiling/tracing |
ac199db0 PZ |
3 | * |
4 | * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com> | |
c530665c | 5 | * Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com> |
ac199db0 PZ |
6 | */ |
7 | ||
558e6547 | 8 | #include <linux/module.h> |
430ad5a6 | 9 | #include <linux/kprobes.h> |
ac199db0 PZ |
10 | #include "trace.h" |
11 | ||
6016ee13 | 12 | static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS]; |
20ab4425 | 13 | |
eb1e7961 FW |
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; | |
ce71b9df | 20 | |
20ab4425 | 21 | /* Count the events in use (per event id, not per instance) */ |
97d5a220 | 22 | static int total_ref_count; |
20ab4425 | 23 | |
61c32659 FW |
24 | static int perf_trace_event_perm(struct ftrace_event_call *tp_event, |
25 | struct perf_event *p_event) | |
26 | { | |
d5b5f391 PZ |
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 | ||
ced39002 | 33 | /* The ftrace function trace is allowed only for root. */ |
cfa77bc4 JO |
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; | |
63c45f4b JO |
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; | |
cfa77bc4 | 52 | } |
ced39002 | 53 | |
61c32659 FW |
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 | ||
ceec0b6f JO |
74 | static int perf_trace_event_reg(struct ftrace_event_call *tp_event, |
75 | struct perf_event *p_event) | |
e5e25cf4 | 76 | { |
6016ee13 | 77 | struct hlist_head __percpu *list; |
ceec0b6f | 78 | int ret = -ENOMEM; |
1c024eca | 79 | int cpu; |
20ab4425 | 80 | |
1c024eca PZ |
81 | p_event->tp_event = tp_event; |
82 | if (tp_event->perf_refcount++ > 0) | |
e5e25cf4 FW |
83 | return 0; |
84 | ||
1c024eca PZ |
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)); | |
20ab4425 | 91 | |
1c024eca | 92 | tp_event->perf_events = list; |
e5e25cf4 | 93 | |
97d5a220 | 94 | if (!total_ref_count) { |
6016ee13 | 95 | char __percpu *buf; |
b7e2ecef | 96 | int i; |
20ab4425 | 97 | |
7ae07ea3 | 98 | for (i = 0; i < PERF_NR_CONTEXTS; i++) { |
6016ee13 | 99 | buf = (char __percpu *)alloc_percpu(perf_trace_t); |
b7e2ecef | 100 | if (!buf) |
1c024eca | 101 | goto fail; |
20ab4425 | 102 | |
1c024eca | 103 | perf_trace_buf[i] = buf; |
b7e2ecef | 104 | } |
20ab4425 FW |
105 | } |
106 | ||
ceec0b6f | 107 | ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL); |
1c024eca PZ |
108 | if (ret) |
109 | goto fail; | |
20ab4425 | 110 | |
1c024eca PZ |
111 | total_ref_count++; |
112 | return 0; | |
113 | ||
114 | fail: | |
97d5a220 | 115 | if (!total_ref_count) { |
b7e2ecef PZ |
116 | int i; |
117 | ||
7ae07ea3 | 118 | for (i = 0; i < PERF_NR_CONTEXTS; i++) { |
b7e2ecef PZ |
119 | free_percpu(perf_trace_buf[i]); |
120 | perf_trace_buf[i] = NULL; | |
121 | } | |
fe8e5b5a | 122 | } |
1c024eca PZ |
123 | |
124 | if (!--tp_event->perf_refcount) { | |
125 | free_percpu(tp_event->perf_events); | |
126 | tp_event->perf_events = NULL; | |
fe8e5b5a | 127 | } |
20ab4425 FW |
128 | |
129 | return ret; | |
e5e25cf4 FW |
130 | } |
131 | ||
ceec0b6f JO |
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 | ||
1c024eca | 195 | int perf_trace_init(struct perf_event *p_event) |
ac199db0 | 196 | { |
1c024eca | 197 | struct ftrace_event_call *tp_event; |
0022cedd | 198 | u64 event_id = p_event->attr.config; |
20c8928a | 199 | int ret = -EINVAL; |
ac199db0 | 200 | |
20c8928a | 201 | mutex_lock(&event_mutex); |
1c024eca | 202 | list_for_each_entry(tp_event, &ftrace_events, list) { |
ff5f149b | 203 | if (tp_event->event.type == event_id && |
a1d0ce82 | 204 | tp_event->class && tp_event->class->reg && |
1c024eca PZ |
205 | try_module_get(tp_event->mod)) { |
206 | ret = perf_trace_event_init(tp_event, p_event); | |
9cb627d5 LZ |
207 | if (ret) |
208 | module_put(tp_event->mod); | |
20c8928a LZ |
209 | break; |
210 | } | |
ac199db0 | 211 | } |
20c8928a | 212 | mutex_unlock(&event_mutex); |
ac199db0 | 213 | |
20c8928a | 214 | return ret; |
ac199db0 PZ |
215 | } |
216 | ||
ceec0b6f JO |
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 | ||
a4eaf7f1 | 225 | int perf_trace_add(struct perf_event *p_event, int flags) |
e5e25cf4 | 226 | { |
1c024eca | 227 | struct ftrace_event_call *tp_event = p_event->tp_event; |
6016ee13 | 228 | struct hlist_head __percpu *pcpu_list; |
1c024eca | 229 | struct hlist_head *list; |
20ab4425 | 230 | |
6016ee13 NK |
231 | pcpu_list = tp_event->perf_events; |
232 | if (WARN_ON_ONCE(!pcpu_list)) | |
1c024eca | 233 | return -EINVAL; |
20ab4425 | 234 | |
a4eaf7f1 PZ |
235 | if (!(flags & PERF_EF_START)) |
236 | p_event->hw.state = PERF_HES_STOPPED; | |
237 | ||
6016ee13 | 238 | list = this_cpu_ptr(pcpu_list); |
1c024eca | 239 | hlist_add_head_rcu(&p_event->hlist_entry, list); |
20ab4425 | 240 | |
489c75c3 | 241 | return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event); |
1c024eca | 242 | } |
20ab4425 | 243 | |
a4eaf7f1 | 244 | void perf_trace_del(struct perf_event *p_event, int flags) |
1c024eca | 245 | { |
489c75c3 | 246 | struct ftrace_event_call *tp_event = p_event->tp_event; |
1c024eca | 247 | hlist_del_rcu(&p_event->hlist_entry); |
489c75c3 | 248 | tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event); |
e5e25cf4 FW |
249 | } |
250 | ||
97d5a220 | 251 | __kprobes void *perf_trace_buf_prepare(int size, unsigned short type, |
b7e2ecef | 252 | struct pt_regs *regs, int *rctxp) |
430ad5a6 XG |
253 | { |
254 | struct trace_entry *entry; | |
87f44bbc | 255 | unsigned long flags; |
1c024eca | 256 | char *raw_data; |
b7e2ecef | 257 | int pc; |
430ad5a6 | 258 | |
eb1e7961 FW |
259 | BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long)); |
260 | ||
cd92bf61 ON |
261 | if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, |
262 | "perf buffer not large enough")) | |
263 | return NULL; | |
264 | ||
430ad5a6 XG |
265 | pc = preempt_count(); |
266 | ||
430ad5a6 XG |
267 | *rctxp = perf_swevent_get_recursion_context(); |
268 | if (*rctxp < 0) | |
1c024eca | 269 | return NULL; |
430ad5a6 | 270 | |
3771f077 | 271 | raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]); |
430ad5a6 XG |
272 | |
273 | /* zero the dead bytes from align to not leak stack to user */ | |
eb1e7961 | 274 | memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64)); |
430ad5a6 XG |
275 | |
276 | entry = (struct trace_entry *)raw_data; | |
87f44bbc PZ |
277 | local_save_flags(flags); |
278 | tracing_generic_entry_update(entry, flags, pc); | |
430ad5a6 XG |
279 | entry->type = type; |
280 | ||
281 | return raw_data; | |
430ad5a6 | 282 | } |
97d5a220 | 283 | EXPORT_SYMBOL_GPL(perf_trace_buf_prepare); |
ced39002 JO |
284 | |
285 | #ifdef CONFIG_FUNCTION_TRACER | |
286 | static void | |
2f5f6ad9 | 287 | perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip, |
a1e2e31d | 288 | struct ftrace_ops *ops, struct pt_regs *pt_regs) |
ced39002 JO |
289 | { |
290 | struct ftrace_entry *entry; | |
291 | struct hlist_head *head; | |
292 | struct pt_regs regs; | |
293 | int rctx; | |
294 | ||
b8ebfd3f ON |
295 | head = this_cpu_ptr(event_function.perf_events); |
296 | if (hlist_empty(head)) | |
297 | return; | |
298 | ||
ced39002 JO |
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(®s); | |
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; | |
ced39002 | 312 | perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0, |
e6dab5ff | 313 | 1, ®s, head, NULL); |
ced39002 JO |
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; | |
5500fa51 JO |
330 | int ret = unregister_ftrace_function(ops); |
331 | ftrace_free_filter(ops); | |
332 | return ret; | |
ced39002 JO |
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 */ |