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; | |
45 | } | |
ced39002 | 46 | |
61c32659 FW |
47 | /* No tracing, just counting, so no obvious leak */ |
48 | if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW)) | |
49 | return 0; | |
50 | ||
51 | /* Some events are ok to be traced by non-root users... */ | |
52 | if (p_event->attach_state == PERF_ATTACH_TASK) { | |
53 | if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY) | |
54 | return 0; | |
55 | } | |
56 | ||
57 | /* | |
58 | * ...otherwise raw tracepoint data can be a severe data leak, | |
59 | * only allow root to have these. | |
60 | */ | |
61 | if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN)) | |
62 | return -EPERM; | |
63 | ||
64 | return 0; | |
65 | } | |
66 | ||
ceec0b6f JO |
67 | static int perf_trace_event_reg(struct ftrace_event_call *tp_event, |
68 | struct perf_event *p_event) | |
e5e25cf4 | 69 | { |
6016ee13 | 70 | struct hlist_head __percpu *list; |
ceec0b6f | 71 | int ret = -ENOMEM; |
1c024eca | 72 | int cpu; |
20ab4425 | 73 | |
1c024eca PZ |
74 | p_event->tp_event = tp_event; |
75 | if (tp_event->perf_refcount++ > 0) | |
e5e25cf4 FW |
76 | return 0; |
77 | ||
1c024eca PZ |
78 | list = alloc_percpu(struct hlist_head); |
79 | if (!list) | |
80 | goto fail; | |
81 | ||
82 | for_each_possible_cpu(cpu) | |
83 | INIT_HLIST_HEAD(per_cpu_ptr(list, cpu)); | |
20ab4425 | 84 | |
1c024eca | 85 | tp_event->perf_events = list; |
e5e25cf4 | 86 | |
97d5a220 | 87 | if (!total_ref_count) { |
6016ee13 | 88 | char __percpu *buf; |
b7e2ecef | 89 | int i; |
20ab4425 | 90 | |
7ae07ea3 | 91 | for (i = 0; i < PERF_NR_CONTEXTS; i++) { |
6016ee13 | 92 | buf = (char __percpu *)alloc_percpu(perf_trace_t); |
b7e2ecef | 93 | if (!buf) |
1c024eca | 94 | goto fail; |
20ab4425 | 95 | |
1c024eca | 96 | perf_trace_buf[i] = buf; |
b7e2ecef | 97 | } |
20ab4425 FW |
98 | } |
99 | ||
ceec0b6f | 100 | ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL); |
1c024eca PZ |
101 | if (ret) |
102 | goto fail; | |
20ab4425 | 103 | |
1c024eca PZ |
104 | total_ref_count++; |
105 | return 0; | |
106 | ||
107 | fail: | |
97d5a220 | 108 | if (!total_ref_count) { |
b7e2ecef PZ |
109 | int i; |
110 | ||
7ae07ea3 | 111 | for (i = 0; i < PERF_NR_CONTEXTS; i++) { |
b7e2ecef PZ |
112 | free_percpu(perf_trace_buf[i]); |
113 | perf_trace_buf[i] = NULL; | |
114 | } | |
fe8e5b5a | 115 | } |
1c024eca PZ |
116 | |
117 | if (!--tp_event->perf_refcount) { | |
118 | free_percpu(tp_event->perf_events); | |
119 | tp_event->perf_events = NULL; | |
fe8e5b5a | 120 | } |
20ab4425 FW |
121 | |
122 | return ret; | |
e5e25cf4 FW |
123 | } |
124 | ||
ceec0b6f JO |
125 | static void perf_trace_event_unreg(struct perf_event *p_event) |
126 | { | |
127 | struct ftrace_event_call *tp_event = p_event->tp_event; | |
128 | int i; | |
129 | ||
130 | if (--tp_event->perf_refcount > 0) | |
131 | goto out; | |
132 | ||
133 | tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL); | |
134 | ||
135 | /* | |
136 | * Ensure our callback won't be called anymore. The buffers | |
137 | * will be freed after that. | |
138 | */ | |
139 | tracepoint_synchronize_unregister(); | |
140 | ||
141 | free_percpu(tp_event->perf_events); | |
142 | tp_event->perf_events = NULL; | |
143 | ||
144 | if (!--total_ref_count) { | |
145 | for (i = 0; i < PERF_NR_CONTEXTS; i++) { | |
146 | free_percpu(perf_trace_buf[i]); | |
147 | perf_trace_buf[i] = NULL; | |
148 | } | |
149 | } | |
150 | out: | |
151 | module_put(tp_event->mod); | |
152 | } | |
153 | ||
154 | static int perf_trace_event_open(struct perf_event *p_event) | |
155 | { | |
156 | struct ftrace_event_call *tp_event = p_event->tp_event; | |
157 | return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event); | |
158 | } | |
159 | ||
160 | static void perf_trace_event_close(struct perf_event *p_event) | |
161 | { | |
162 | struct ftrace_event_call *tp_event = p_event->tp_event; | |
163 | tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event); | |
164 | } | |
165 | ||
166 | static int perf_trace_event_init(struct ftrace_event_call *tp_event, | |
167 | struct perf_event *p_event) | |
168 | { | |
169 | int ret; | |
170 | ||
171 | ret = perf_trace_event_perm(tp_event, p_event); | |
172 | if (ret) | |
173 | return ret; | |
174 | ||
175 | ret = perf_trace_event_reg(tp_event, p_event); | |
176 | if (ret) | |
177 | return ret; | |
178 | ||
179 | ret = perf_trace_event_open(p_event); | |
180 | if (ret) { | |
181 | perf_trace_event_unreg(p_event); | |
182 | return ret; | |
183 | } | |
184 | ||
185 | return 0; | |
186 | } | |
187 | ||
1c024eca | 188 | int perf_trace_init(struct perf_event *p_event) |
ac199db0 | 189 | { |
1c024eca | 190 | struct ftrace_event_call *tp_event; |
0022cedd | 191 | u64 event_id = p_event->attr.config; |
20c8928a | 192 | int ret = -EINVAL; |
ac199db0 | 193 | |
20c8928a | 194 | mutex_lock(&event_mutex); |
1c024eca | 195 | list_for_each_entry(tp_event, &ftrace_events, list) { |
ff5f149b | 196 | if (tp_event->event.type == event_id && |
a1d0ce82 | 197 | tp_event->class && tp_event->class->reg && |
1c024eca PZ |
198 | try_module_get(tp_event->mod)) { |
199 | ret = perf_trace_event_init(tp_event, p_event); | |
9cb627d5 LZ |
200 | if (ret) |
201 | module_put(tp_event->mod); | |
20c8928a LZ |
202 | break; |
203 | } | |
ac199db0 | 204 | } |
20c8928a | 205 | mutex_unlock(&event_mutex); |
ac199db0 | 206 | |
20c8928a | 207 | return ret; |
ac199db0 PZ |
208 | } |
209 | ||
ceec0b6f JO |
210 | void perf_trace_destroy(struct perf_event *p_event) |
211 | { | |
212 | mutex_lock(&event_mutex); | |
213 | perf_trace_event_close(p_event); | |
214 | perf_trace_event_unreg(p_event); | |
215 | mutex_unlock(&event_mutex); | |
216 | } | |
217 | ||
a4eaf7f1 | 218 | int perf_trace_add(struct perf_event *p_event, int flags) |
e5e25cf4 | 219 | { |
1c024eca | 220 | struct ftrace_event_call *tp_event = p_event->tp_event; |
6016ee13 | 221 | struct hlist_head __percpu *pcpu_list; |
1c024eca | 222 | struct hlist_head *list; |
20ab4425 | 223 | |
6016ee13 NK |
224 | pcpu_list = tp_event->perf_events; |
225 | if (WARN_ON_ONCE(!pcpu_list)) | |
1c024eca | 226 | return -EINVAL; |
20ab4425 | 227 | |
a4eaf7f1 PZ |
228 | if (!(flags & PERF_EF_START)) |
229 | p_event->hw.state = PERF_HES_STOPPED; | |
230 | ||
6016ee13 | 231 | list = this_cpu_ptr(pcpu_list); |
1c024eca | 232 | hlist_add_head_rcu(&p_event->hlist_entry, list); |
20ab4425 | 233 | |
489c75c3 | 234 | return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event); |
1c024eca | 235 | } |
20ab4425 | 236 | |
a4eaf7f1 | 237 | void perf_trace_del(struct perf_event *p_event, int flags) |
1c024eca | 238 | { |
489c75c3 | 239 | struct ftrace_event_call *tp_event = p_event->tp_event; |
1c024eca | 240 | hlist_del_rcu(&p_event->hlist_entry); |
489c75c3 | 241 | tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event); |
e5e25cf4 FW |
242 | } |
243 | ||
97d5a220 | 244 | __kprobes void *perf_trace_buf_prepare(int size, unsigned short type, |
b7e2ecef | 245 | struct pt_regs *regs, int *rctxp) |
430ad5a6 XG |
246 | { |
247 | struct trace_entry *entry; | |
87f44bbc | 248 | unsigned long flags; |
1c024eca | 249 | char *raw_data; |
b7e2ecef | 250 | int pc; |
430ad5a6 | 251 | |
eb1e7961 FW |
252 | BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long)); |
253 | ||
cd92bf61 ON |
254 | if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, |
255 | "perf buffer not large enough")) | |
256 | return NULL; | |
257 | ||
430ad5a6 XG |
258 | pc = preempt_count(); |
259 | ||
430ad5a6 XG |
260 | *rctxp = perf_swevent_get_recursion_context(); |
261 | if (*rctxp < 0) | |
1c024eca | 262 | return NULL; |
430ad5a6 | 263 | |
3771f077 | 264 | raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]); |
430ad5a6 XG |
265 | |
266 | /* zero the dead bytes from align to not leak stack to user */ | |
eb1e7961 | 267 | memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64)); |
430ad5a6 XG |
268 | |
269 | entry = (struct trace_entry *)raw_data; | |
87f44bbc PZ |
270 | local_save_flags(flags); |
271 | tracing_generic_entry_update(entry, flags, pc); | |
430ad5a6 XG |
272 | entry->type = type; |
273 | ||
274 | return raw_data; | |
430ad5a6 | 275 | } |
97d5a220 | 276 | EXPORT_SYMBOL_GPL(perf_trace_buf_prepare); |
ced39002 JO |
277 | |
278 | #ifdef CONFIG_FUNCTION_TRACER | |
279 | static void | |
2f5f6ad9 | 280 | perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip, |
a1e2e31d | 281 | struct ftrace_ops *ops, struct pt_regs *pt_regs) |
ced39002 JO |
282 | { |
283 | struct ftrace_entry *entry; | |
284 | struct hlist_head *head; | |
285 | struct pt_regs regs; | |
286 | int rctx; | |
287 | ||
b8ebfd3f ON |
288 | head = this_cpu_ptr(event_function.perf_events); |
289 | if (hlist_empty(head)) | |
290 | return; | |
291 | ||
ced39002 JO |
292 | #define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \ |
293 | sizeof(u64)) - sizeof(u32)) | |
294 | ||
295 | BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE); | |
296 | ||
297 | perf_fetch_caller_regs(®s); | |
298 | ||
299 | entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx); | |
300 | if (!entry) | |
301 | return; | |
302 | ||
303 | entry->ip = ip; | |
304 | entry->parent_ip = parent_ip; | |
ced39002 | 305 | perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0, |
e6dab5ff | 306 | 1, ®s, head, NULL); |
ced39002 JO |
307 | |
308 | #undef ENTRY_SIZE | |
309 | } | |
310 | ||
311 | static int perf_ftrace_function_register(struct perf_event *event) | |
312 | { | |
313 | struct ftrace_ops *ops = &event->ftrace_ops; | |
314 | ||
315 | ops->flags |= FTRACE_OPS_FL_CONTROL; | |
316 | ops->func = perf_ftrace_function_call; | |
317 | return register_ftrace_function(ops); | |
318 | } | |
319 | ||
320 | static int perf_ftrace_function_unregister(struct perf_event *event) | |
321 | { | |
322 | struct ftrace_ops *ops = &event->ftrace_ops; | |
5500fa51 JO |
323 | int ret = unregister_ftrace_function(ops); |
324 | ftrace_free_filter(ops); | |
325 | return ret; | |
ced39002 JO |
326 | } |
327 | ||
328 | static void perf_ftrace_function_enable(struct perf_event *event) | |
329 | { | |
330 | ftrace_function_local_enable(&event->ftrace_ops); | |
331 | } | |
332 | ||
333 | static void perf_ftrace_function_disable(struct perf_event *event) | |
334 | { | |
335 | ftrace_function_local_disable(&event->ftrace_ops); | |
336 | } | |
337 | ||
338 | int perf_ftrace_event_register(struct ftrace_event_call *call, | |
339 | enum trace_reg type, void *data) | |
340 | { | |
341 | switch (type) { | |
342 | case TRACE_REG_REGISTER: | |
343 | case TRACE_REG_UNREGISTER: | |
344 | break; | |
345 | case TRACE_REG_PERF_REGISTER: | |
346 | case TRACE_REG_PERF_UNREGISTER: | |
347 | return 0; | |
348 | case TRACE_REG_PERF_OPEN: | |
349 | return perf_ftrace_function_register(data); | |
350 | case TRACE_REG_PERF_CLOSE: | |
351 | return perf_ftrace_function_unregister(data); | |
352 | case TRACE_REG_PERF_ADD: | |
353 | perf_ftrace_function_enable(data); | |
354 | return 0; | |
355 | case TRACE_REG_PERF_DEL: | |
356 | perf_ftrace_function_disable(data); | |
357 | return 0; | |
358 | } | |
359 | ||
360 | return -EINVAL; | |
361 | } | |
362 | #endif /* CONFIG_FUNCTION_TRACER */ |