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 JO |
33 | /* The ftrace function trace is allowed only for root. */ |
34 | if (ftrace_event_is_function(tp_event) && | |
12ae030d | 35 | perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN)) |
ced39002 JO |
36 | return -EPERM; |
37 | ||
61c32659 FW |
38 | /* No tracing, just counting, so no obvious leak */ |
39 | if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW)) | |
40 | return 0; | |
41 | ||
42 | /* Some events are ok to be traced by non-root users... */ | |
43 | if (p_event->attach_state == PERF_ATTACH_TASK) { | |
44 | if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY) | |
45 | return 0; | |
46 | } | |
47 | ||
48 | /* | |
49 | * ...otherwise raw tracepoint data can be a severe data leak, | |
50 | * only allow root to have these. | |
51 | */ | |
52 | if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN)) | |
53 | return -EPERM; | |
54 | ||
55 | return 0; | |
56 | } | |
57 | ||
ceec0b6f JO |
58 | static int perf_trace_event_reg(struct ftrace_event_call *tp_event, |
59 | struct perf_event *p_event) | |
e5e25cf4 | 60 | { |
6016ee13 | 61 | struct hlist_head __percpu *list; |
ceec0b6f | 62 | int ret = -ENOMEM; |
1c024eca | 63 | int cpu; |
20ab4425 | 64 | |
1c024eca PZ |
65 | p_event->tp_event = tp_event; |
66 | if (tp_event->perf_refcount++ > 0) | |
e5e25cf4 FW |
67 | return 0; |
68 | ||
1c024eca PZ |
69 | list = alloc_percpu(struct hlist_head); |
70 | if (!list) | |
71 | goto fail; | |
72 | ||
73 | for_each_possible_cpu(cpu) | |
74 | INIT_HLIST_HEAD(per_cpu_ptr(list, cpu)); | |
20ab4425 | 75 | |
1c024eca | 76 | tp_event->perf_events = list; |
e5e25cf4 | 77 | |
97d5a220 | 78 | if (!total_ref_count) { |
6016ee13 | 79 | char __percpu *buf; |
b7e2ecef | 80 | int i; |
20ab4425 | 81 | |
7ae07ea3 | 82 | for (i = 0; i < PERF_NR_CONTEXTS; i++) { |
6016ee13 | 83 | buf = (char __percpu *)alloc_percpu(perf_trace_t); |
b7e2ecef | 84 | if (!buf) |
1c024eca | 85 | goto fail; |
20ab4425 | 86 | |
1c024eca | 87 | perf_trace_buf[i] = buf; |
b7e2ecef | 88 | } |
20ab4425 FW |
89 | } |
90 | ||
ceec0b6f | 91 | ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL); |
1c024eca PZ |
92 | if (ret) |
93 | goto fail; | |
20ab4425 | 94 | |
1c024eca PZ |
95 | total_ref_count++; |
96 | return 0; | |
97 | ||
98 | fail: | |
97d5a220 | 99 | if (!total_ref_count) { |
b7e2ecef PZ |
100 | int i; |
101 | ||
7ae07ea3 | 102 | for (i = 0; i < PERF_NR_CONTEXTS; i++) { |
b7e2ecef PZ |
103 | free_percpu(perf_trace_buf[i]); |
104 | perf_trace_buf[i] = NULL; | |
105 | } | |
fe8e5b5a | 106 | } |
1c024eca PZ |
107 | |
108 | if (!--tp_event->perf_refcount) { | |
109 | free_percpu(tp_event->perf_events); | |
110 | tp_event->perf_events = NULL; | |
fe8e5b5a | 111 | } |
20ab4425 FW |
112 | |
113 | return ret; | |
e5e25cf4 FW |
114 | } |
115 | ||
ceec0b6f JO |
116 | static void perf_trace_event_unreg(struct perf_event *p_event) |
117 | { | |
118 | struct ftrace_event_call *tp_event = p_event->tp_event; | |
119 | int i; | |
120 | ||
121 | if (--tp_event->perf_refcount > 0) | |
122 | goto out; | |
123 | ||
124 | tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL); | |
125 | ||
126 | /* | |
127 | * Ensure our callback won't be called anymore. The buffers | |
128 | * will be freed after that. | |
129 | */ | |
130 | tracepoint_synchronize_unregister(); | |
131 | ||
132 | free_percpu(tp_event->perf_events); | |
133 | tp_event->perf_events = NULL; | |
134 | ||
135 | if (!--total_ref_count) { | |
136 | for (i = 0; i < PERF_NR_CONTEXTS; i++) { | |
137 | free_percpu(perf_trace_buf[i]); | |
138 | perf_trace_buf[i] = NULL; | |
139 | } | |
140 | } | |
141 | out: | |
142 | module_put(tp_event->mod); | |
143 | } | |
144 | ||
145 | static int perf_trace_event_open(struct perf_event *p_event) | |
146 | { | |
147 | struct ftrace_event_call *tp_event = p_event->tp_event; | |
148 | return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event); | |
149 | } | |
150 | ||
151 | static void perf_trace_event_close(struct perf_event *p_event) | |
152 | { | |
153 | struct ftrace_event_call *tp_event = p_event->tp_event; | |
154 | tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event); | |
155 | } | |
156 | ||
157 | static int perf_trace_event_init(struct ftrace_event_call *tp_event, | |
158 | struct perf_event *p_event) | |
159 | { | |
160 | int ret; | |
161 | ||
162 | ret = perf_trace_event_perm(tp_event, p_event); | |
163 | if (ret) | |
164 | return ret; | |
165 | ||
166 | ret = perf_trace_event_reg(tp_event, p_event); | |
167 | if (ret) | |
168 | return ret; | |
169 | ||
170 | ret = perf_trace_event_open(p_event); | |
171 | if (ret) { | |
172 | perf_trace_event_unreg(p_event); | |
173 | return ret; | |
174 | } | |
175 | ||
176 | return 0; | |
177 | } | |
178 | ||
1c024eca | 179 | int perf_trace_init(struct perf_event *p_event) |
ac199db0 | 180 | { |
1c024eca | 181 | struct ftrace_event_call *tp_event; |
0022cedd | 182 | u64 event_id = p_event->attr.config; |
20c8928a | 183 | int ret = -EINVAL; |
ac199db0 | 184 | |
20c8928a | 185 | mutex_lock(&event_mutex); |
1c024eca | 186 | list_for_each_entry(tp_event, &ftrace_events, list) { |
ff5f149b | 187 | if (tp_event->event.type == event_id && |
a1d0ce82 | 188 | tp_event->class && tp_event->class->reg && |
1c024eca PZ |
189 | try_module_get(tp_event->mod)) { |
190 | ret = perf_trace_event_init(tp_event, p_event); | |
9cb627d5 LZ |
191 | if (ret) |
192 | module_put(tp_event->mod); | |
20c8928a LZ |
193 | break; |
194 | } | |
ac199db0 | 195 | } |
20c8928a | 196 | mutex_unlock(&event_mutex); |
ac199db0 | 197 | |
20c8928a | 198 | return ret; |
ac199db0 PZ |
199 | } |
200 | ||
ceec0b6f JO |
201 | void perf_trace_destroy(struct perf_event *p_event) |
202 | { | |
203 | mutex_lock(&event_mutex); | |
204 | perf_trace_event_close(p_event); | |
205 | perf_trace_event_unreg(p_event); | |
206 | mutex_unlock(&event_mutex); | |
207 | } | |
208 | ||
a4eaf7f1 | 209 | int perf_trace_add(struct perf_event *p_event, int flags) |
e5e25cf4 | 210 | { |
1c024eca | 211 | struct ftrace_event_call *tp_event = p_event->tp_event; |
6016ee13 | 212 | struct hlist_head __percpu *pcpu_list; |
1c024eca | 213 | struct hlist_head *list; |
20ab4425 | 214 | |
6016ee13 NK |
215 | pcpu_list = tp_event->perf_events; |
216 | if (WARN_ON_ONCE(!pcpu_list)) | |
1c024eca | 217 | return -EINVAL; |
20ab4425 | 218 | |
a4eaf7f1 PZ |
219 | if (!(flags & PERF_EF_START)) |
220 | p_event->hw.state = PERF_HES_STOPPED; | |
221 | ||
6016ee13 | 222 | list = this_cpu_ptr(pcpu_list); |
1c024eca | 223 | hlist_add_head_rcu(&p_event->hlist_entry, list); |
20ab4425 | 224 | |
489c75c3 | 225 | return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event); |
1c024eca | 226 | } |
20ab4425 | 227 | |
a4eaf7f1 | 228 | void perf_trace_del(struct perf_event *p_event, int flags) |
1c024eca | 229 | { |
489c75c3 | 230 | struct ftrace_event_call *tp_event = p_event->tp_event; |
1c024eca | 231 | hlist_del_rcu(&p_event->hlist_entry); |
489c75c3 | 232 | tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event); |
e5e25cf4 FW |
233 | } |
234 | ||
97d5a220 | 235 | __kprobes void *perf_trace_buf_prepare(int size, unsigned short type, |
b7e2ecef | 236 | struct pt_regs *regs, int *rctxp) |
430ad5a6 XG |
237 | { |
238 | struct trace_entry *entry; | |
87f44bbc | 239 | unsigned long flags; |
1c024eca | 240 | char *raw_data; |
b7e2ecef | 241 | int pc; |
430ad5a6 | 242 | |
eb1e7961 FW |
243 | BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long)); |
244 | ||
cd92bf61 ON |
245 | if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, |
246 | "perf buffer not large enough")) | |
247 | return NULL; | |
248 | ||
430ad5a6 XG |
249 | pc = preempt_count(); |
250 | ||
430ad5a6 XG |
251 | *rctxp = perf_swevent_get_recursion_context(); |
252 | if (*rctxp < 0) | |
1c024eca | 253 | return NULL; |
430ad5a6 | 254 | |
3771f077 | 255 | raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]); |
430ad5a6 XG |
256 | |
257 | /* zero the dead bytes from align to not leak stack to user */ | |
eb1e7961 | 258 | memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64)); |
430ad5a6 XG |
259 | |
260 | entry = (struct trace_entry *)raw_data; | |
87f44bbc PZ |
261 | local_save_flags(flags); |
262 | tracing_generic_entry_update(entry, flags, pc); | |
430ad5a6 XG |
263 | entry->type = type; |
264 | ||
265 | return raw_data; | |
430ad5a6 | 266 | } |
97d5a220 | 267 | EXPORT_SYMBOL_GPL(perf_trace_buf_prepare); |
ced39002 JO |
268 | |
269 | #ifdef CONFIG_FUNCTION_TRACER | |
270 | static void | |
2f5f6ad9 | 271 | perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip, |
a1e2e31d | 272 | struct ftrace_ops *ops, struct pt_regs *pt_regs) |
ced39002 JO |
273 | { |
274 | struct ftrace_entry *entry; | |
275 | struct hlist_head *head; | |
276 | struct pt_regs regs; | |
277 | int rctx; | |
278 | ||
b8ebfd3f ON |
279 | head = this_cpu_ptr(event_function.perf_events); |
280 | if (hlist_empty(head)) | |
281 | return; | |
282 | ||
ced39002 JO |
283 | #define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \ |
284 | sizeof(u64)) - sizeof(u32)) | |
285 | ||
286 | BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE); | |
287 | ||
288 | perf_fetch_caller_regs(®s); | |
289 | ||
290 | entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx); | |
291 | if (!entry) | |
292 | return; | |
293 | ||
294 | entry->ip = ip; | |
295 | entry->parent_ip = parent_ip; | |
ced39002 | 296 | perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0, |
e6dab5ff | 297 | 1, ®s, head, NULL); |
ced39002 JO |
298 | |
299 | #undef ENTRY_SIZE | |
300 | } | |
301 | ||
302 | static int perf_ftrace_function_register(struct perf_event *event) | |
303 | { | |
304 | struct ftrace_ops *ops = &event->ftrace_ops; | |
305 | ||
306 | ops->flags |= FTRACE_OPS_FL_CONTROL; | |
307 | ops->func = perf_ftrace_function_call; | |
308 | return register_ftrace_function(ops); | |
309 | } | |
310 | ||
311 | static int perf_ftrace_function_unregister(struct perf_event *event) | |
312 | { | |
313 | struct ftrace_ops *ops = &event->ftrace_ops; | |
5500fa51 JO |
314 | int ret = unregister_ftrace_function(ops); |
315 | ftrace_free_filter(ops); | |
316 | return ret; | |
ced39002 JO |
317 | } |
318 | ||
319 | static void perf_ftrace_function_enable(struct perf_event *event) | |
320 | { | |
321 | ftrace_function_local_enable(&event->ftrace_ops); | |
322 | } | |
323 | ||
324 | static void perf_ftrace_function_disable(struct perf_event *event) | |
325 | { | |
326 | ftrace_function_local_disable(&event->ftrace_ops); | |
327 | } | |
328 | ||
329 | int perf_ftrace_event_register(struct ftrace_event_call *call, | |
330 | enum trace_reg type, void *data) | |
331 | { | |
332 | switch (type) { | |
333 | case TRACE_REG_REGISTER: | |
334 | case TRACE_REG_UNREGISTER: | |
335 | break; | |
336 | case TRACE_REG_PERF_REGISTER: | |
337 | case TRACE_REG_PERF_UNREGISTER: | |
338 | return 0; | |
339 | case TRACE_REG_PERF_OPEN: | |
340 | return perf_ftrace_function_register(data); | |
341 | case TRACE_REG_PERF_CLOSE: | |
342 | return perf_ftrace_function_unregister(data); | |
343 | case TRACE_REG_PERF_ADD: | |
344 | perf_ftrace_function_enable(data); | |
345 | return 0; | |
346 | case TRACE_REG_PERF_DEL: | |
347 | perf_ftrace_function_disable(data); | |
348 | return 0; | |
349 | } | |
350 | ||
351 | return -EINVAL; | |
352 | } | |
353 | #endif /* CONFIG_FUNCTION_TRACER */ |