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1/*
2 * trace event based perf event profiling/tracing
3 *
4 * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra
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
12static 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 */
18typedef 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) */
22static int total_ref_count;
23
24static int perf_trace_event_perm(struct trace_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 /*
34 * We checked and allowed to create parent,
35 * allow children without checking.
36 */
37 if (p_event->parent)
38 return 0;
39
40 /*
41 * It's ok to check current process (owner) permissions in here,
42 * because code below is called only via perf_event_open syscall.
43 */
44
45 /* The ftrace function trace is allowed only for root. */
46 if (ftrace_event_is_function(tp_event)) {
47 if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
48 return -EPERM;
49
50 /*
51 * We don't allow user space callchains for function trace
52 * event, due to issues with page faults while tracing page
53 * fault handler and its overall trickiness nature.
54 */
55 if (!p_event->attr.exclude_callchain_user)
56 return -EINVAL;
57
58 /*
59 * Same reason to disable user stack dump as for user space
60 * callchains above.
61 */
62 if (p_event->attr.sample_type & PERF_SAMPLE_STACK_USER)
63 return -EINVAL;
64 }
65
66 /* No tracing, just counting, so no obvious leak */
67 if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
68 return 0;
69
70 /* Some events are ok to be traced by non-root users... */
71 if (p_event->attach_state == PERF_ATTACH_TASK) {
72 if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY)
73 return 0;
74 }
75
76 /*
77 * ...otherwise raw tracepoint data can be a severe data leak,
78 * only allow root to have these.
79 */
80 if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
81 return -EPERM;
82
83 return 0;
84}
85
86static int perf_trace_event_reg(struct trace_event_call *tp_event,
87 struct perf_event *p_event)
88{
89 struct hlist_head __percpu *list;
90 int ret = -ENOMEM;
91 int cpu;
92
93 p_event->tp_event = tp_event;
94 if (tp_event->perf_refcount++ > 0)
95 return 0;
96
97 list = alloc_percpu(struct hlist_head);
98 if (!list)
99 goto fail;
100
101 for_each_possible_cpu(cpu)
102 INIT_HLIST_HEAD(per_cpu_ptr(list, cpu));
103
104 tp_event->perf_events = list;
105
106 if (!total_ref_count) {
107 char __percpu *buf;
108 int i;
109
110 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
111 buf = (char __percpu *)alloc_percpu(perf_trace_t);
112 if (!buf)
113 goto fail;
114
115 perf_trace_buf[i] = buf;
116 }
117 }
118
119 ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL);
120 if (ret)
121 goto fail;
122
123 total_ref_count++;
124 return 0;
125
126fail:
127 if (!total_ref_count) {
128 int i;
129
130 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
131 free_percpu(perf_trace_buf[i]);
132 perf_trace_buf[i] = NULL;
133 }
134 }
135
136 if (!--tp_event->perf_refcount) {
137 free_percpu(tp_event->perf_events);
138 tp_event->perf_events = NULL;
139 }
140
141 return ret;
142}
143
144static void perf_trace_event_unreg(struct perf_event *p_event)
145{
146 struct trace_event_call *tp_event = p_event->tp_event;
147 int i;
148
149 if (--tp_event->perf_refcount > 0)
150 goto out;
151
152 tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL);
153
154 /*
155 * Ensure our callback won't be called anymore. The buffers
156 * will be freed after that.
157 */
158 tracepoint_synchronize_unregister();
159
160 free_percpu(tp_event->perf_events);
161 tp_event->perf_events = NULL;
162
163 if (!--total_ref_count) {
164 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
165 free_percpu(perf_trace_buf[i]);
166 perf_trace_buf[i] = NULL;
167 }
168 }
169out:
170 module_put(tp_event->mod);
171}
172
173static int perf_trace_event_open(struct perf_event *p_event)
174{
175 struct trace_event_call *tp_event = p_event->tp_event;
176 return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event);
177}
178
179static void perf_trace_event_close(struct perf_event *p_event)
180{
181 struct trace_event_call *tp_event = p_event->tp_event;
182 tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);
183}
184
185static int perf_trace_event_init(struct trace_event_call *tp_event,
186 struct perf_event *p_event)
187{
188 int ret;
189
190 ret = perf_trace_event_perm(tp_event, p_event);
191 if (ret)
192 return ret;
193
194 ret = perf_trace_event_reg(tp_event, p_event);
195 if (ret)
196 return ret;
197
198 ret = perf_trace_event_open(p_event);
199 if (ret) {
200 perf_trace_event_unreg(p_event);
201 return ret;
202 }
203
204 return 0;
205}
206
207int perf_trace_init(struct perf_event *p_event)
208{
209 struct trace_event_call *tp_event;
210 u64 event_id = p_event->attr.config;
211 int ret = -EINVAL;
212
213 mutex_lock(&event_mutex);
214 list_for_each_entry(tp_event, &ftrace_events, list) {
215 if (tp_event->event.type == event_id &&
216 tp_event->class && tp_event->class->reg &&
217 try_module_get(tp_event->mod)) {
218 ret = perf_trace_event_init(tp_event, p_event);
219 if (ret)
220 module_put(tp_event->mod);
221 break;
222 }
223 }
224 mutex_unlock(&event_mutex);
225
226 return ret;
227}
228
229void perf_trace_destroy(struct perf_event *p_event)
230{
231 mutex_lock(&event_mutex);
232 perf_trace_event_close(p_event);
233 perf_trace_event_unreg(p_event);
234 mutex_unlock(&event_mutex);
235}
236
237int perf_trace_add(struct perf_event *p_event, int flags)
238{
239 struct trace_event_call *tp_event = p_event->tp_event;
240 struct hlist_head __percpu *pcpu_list;
241 struct hlist_head *list;
242
243 pcpu_list = tp_event->perf_events;
244 if (WARN_ON_ONCE(!pcpu_list))
245 return -EINVAL;
246
247 if (!(flags & PERF_EF_START))
248 p_event->hw.state = PERF_HES_STOPPED;
249
250 list = this_cpu_ptr(pcpu_list);
251 hlist_add_head_rcu(&p_event->hlist_entry, list);
252
253 return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event);
254}
255
256void perf_trace_del(struct perf_event *p_event, int flags)
257{
258 struct trace_event_call *tp_event = p_event->tp_event;
259 hlist_del_rcu(&p_event->hlist_entry);
260 tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event);
261}
262
263void *perf_trace_buf_prepare(int size, unsigned short type,
264 struct pt_regs **regs, int *rctxp)
265{
266 struct trace_entry *entry;
267 unsigned long flags;
268 char *raw_data;
269 int pc;
270
271 BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
272
273 if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
274 "perf buffer not large enough"))
275 return NULL;
276
277 pc = preempt_count();
278
279 *rctxp = perf_swevent_get_recursion_context();
280 if (*rctxp < 0)
281 return NULL;
282
283 if (regs)
284 *regs = this_cpu_ptr(&__perf_regs[*rctxp]);
285 raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]);
286
287 /* zero the dead bytes from align to not leak stack to user */
288 memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
289
290 entry = (struct trace_entry *)raw_data;
291 local_save_flags(flags);
292 tracing_generic_entry_update(entry, flags, pc);
293 entry->type = type;
294
295 return raw_data;
296}
297EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
298NOKPROBE_SYMBOL(perf_trace_buf_prepare);
299
300#ifdef CONFIG_FUNCTION_TRACER
301static void
302perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
303 struct ftrace_ops *ops, struct pt_regs *pt_regs)
304{
305 struct ftrace_entry *entry;
306 struct hlist_head *head;
307 struct pt_regs regs;
308 int rctx;
309
310 head = this_cpu_ptr(event_function.perf_events);
311 if (hlist_empty(head))
312 return;
313
314#define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
315 sizeof(u64)) - sizeof(u32))
316
317 BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);
318
319 perf_fetch_caller_regs(®s);
320
321 entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx);
322 if (!entry)
323 return;
324
325 entry->ip = ip;
326 entry->parent_ip = parent_ip;
327 perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
328 1, ®s, head, NULL);
329
330#undef ENTRY_SIZE
331}
332
333static int perf_ftrace_function_register(struct perf_event *event)
334{
335 struct ftrace_ops *ops = &event->ftrace_ops;
336
337 ops->flags |= FTRACE_OPS_FL_PER_CPU | FTRACE_OPS_FL_RCU;
338 ops->func = perf_ftrace_function_call;
339 return register_ftrace_function(ops);
340}
341
342static int perf_ftrace_function_unregister(struct perf_event *event)
343{
344 struct ftrace_ops *ops = &event->ftrace_ops;
345 int ret = unregister_ftrace_function(ops);
346 ftrace_free_filter(ops);
347 return ret;
348}
349
350static void perf_ftrace_function_enable(struct perf_event *event)
351{
352 ftrace_function_local_enable(&event->ftrace_ops);
353}
354
355static void perf_ftrace_function_disable(struct perf_event *event)
356{
357 ftrace_function_local_disable(&event->ftrace_ops);
358}
359
360int perf_ftrace_event_register(struct trace_event_call *call,
361 enum trace_reg type, void *data)
362{
363 switch (type) {
364 case TRACE_REG_REGISTER:
365 case TRACE_REG_UNREGISTER:
366 break;
367 case TRACE_REG_PERF_REGISTER:
368 case TRACE_REG_PERF_UNREGISTER:
369 return 0;
370 case TRACE_REG_PERF_OPEN:
371 return perf_ftrace_function_register(data);
372 case TRACE_REG_PERF_CLOSE:
373 return perf_ftrace_function_unregister(data);
374 case TRACE_REG_PERF_ADD:
375 perf_ftrace_function_enable(data);
376 return 0;
377 case TRACE_REG_PERF_DEL:
378 perf_ftrace_function_disable(data);
379 return 0;
380 }
381
382 return -EINVAL;
383}
384#endif /* CONFIG_FUNCTION_TRACER */
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * trace event based perf event profiling/tracing
4 *
5 * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra
6 * Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com>
7 */
8
9#include <linux/module.h>
10#include <linux/kprobes.h>
11#include <linux/security.h>
12#include "trace.h"
13#include "trace_probe.h"
14
15static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS];
16
17/*
18 * Force it to be aligned to unsigned long to avoid misaligned accesses
19 * suprises
20 */
21typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
22 perf_trace_t;
23
24/* Count the events in use (per event id, not per instance) */
25static int total_ref_count;
26
27static int perf_trace_event_perm(struct trace_event_call *tp_event,
28 struct perf_event *p_event)
29{
30 int ret;
31
32 if (tp_event->perf_perm) {
33 ret = tp_event->perf_perm(tp_event, p_event);
34 if (ret)
35 return ret;
36 }
37
38 /*
39 * We checked and allowed to create parent,
40 * allow children without checking.
41 */
42 if (p_event->parent)
43 return 0;
44
45 /*
46 * It's ok to check current process (owner) permissions in here,
47 * because code below is called only via perf_event_open syscall.
48 */
49
50 /* The ftrace function trace is allowed only for root. */
51 if (ftrace_event_is_function(tp_event)) {
52 ret = perf_allow_tracepoint(&p_event->attr);
53 if (ret)
54 return ret;
55
56 if (!is_sampling_event(p_event))
57 return 0;
58
59 /*
60 * We don't allow user space callchains for function trace
61 * event, due to issues with page faults while tracing page
62 * fault handler and its overall trickiness nature.
63 */
64 if (!p_event->attr.exclude_callchain_user)
65 return -EINVAL;
66
67 /*
68 * Same reason to disable user stack dump as for user space
69 * callchains above.
70 */
71 if (p_event->attr.sample_type & PERF_SAMPLE_STACK_USER)
72 return -EINVAL;
73 }
74
75 /* No tracing, just counting, so no obvious leak */
76 if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
77 return 0;
78
79 /* Some events are ok to be traced by non-root users... */
80 if (p_event->attach_state == PERF_ATTACH_TASK) {
81 if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY)
82 return 0;
83 }
84
85 /*
86 * ...otherwise raw tracepoint data can be a severe data leak,
87 * only allow root to have these.
88 */
89 ret = perf_allow_tracepoint(&p_event->attr);
90 if (ret)
91 return ret;
92
93 return 0;
94}
95
96static int perf_trace_event_reg(struct trace_event_call *tp_event,
97 struct perf_event *p_event)
98{
99 struct hlist_head __percpu *list;
100 int ret = -ENOMEM;
101 int cpu;
102
103 p_event->tp_event = tp_event;
104 if (tp_event->perf_refcount++ > 0)
105 return 0;
106
107 list = alloc_percpu(struct hlist_head);
108 if (!list)
109 goto fail;
110
111 for_each_possible_cpu(cpu)
112 INIT_HLIST_HEAD(per_cpu_ptr(list, cpu));
113
114 tp_event->perf_events = list;
115
116 if (!total_ref_count) {
117 char __percpu *buf;
118 int i;
119
120 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
121 buf = (char __percpu *)alloc_percpu(perf_trace_t);
122 if (!buf)
123 goto fail;
124
125 perf_trace_buf[i] = buf;
126 }
127 }
128
129 ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL);
130 if (ret)
131 goto fail;
132
133 total_ref_count++;
134 return 0;
135
136fail:
137 if (!total_ref_count) {
138 int i;
139
140 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
141 free_percpu(perf_trace_buf[i]);
142 perf_trace_buf[i] = NULL;
143 }
144 }
145
146 if (!--tp_event->perf_refcount) {
147 free_percpu(tp_event->perf_events);
148 tp_event->perf_events = NULL;
149 }
150
151 return ret;
152}
153
154static void perf_trace_event_unreg(struct perf_event *p_event)
155{
156 struct trace_event_call *tp_event = p_event->tp_event;
157 int i;
158
159 if (--tp_event->perf_refcount > 0)
160 goto out;
161
162 tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL);
163
164 /*
165 * Ensure our callback won't be called anymore. The buffers
166 * will be freed after that.
167 */
168 tracepoint_synchronize_unregister();
169
170 free_percpu(tp_event->perf_events);
171 tp_event->perf_events = NULL;
172
173 if (!--total_ref_count) {
174 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
175 free_percpu(perf_trace_buf[i]);
176 perf_trace_buf[i] = NULL;
177 }
178 }
179out:
180 module_put(tp_event->mod);
181}
182
183static int perf_trace_event_open(struct perf_event *p_event)
184{
185 struct trace_event_call *tp_event = p_event->tp_event;
186 return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event);
187}
188
189static void perf_trace_event_close(struct perf_event *p_event)
190{
191 struct trace_event_call *tp_event = p_event->tp_event;
192 tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);
193}
194
195static int perf_trace_event_init(struct trace_event_call *tp_event,
196 struct perf_event *p_event)
197{
198 int ret;
199
200 ret = perf_trace_event_perm(tp_event, p_event);
201 if (ret)
202 return ret;
203
204 ret = perf_trace_event_reg(tp_event, p_event);
205 if (ret)
206 return ret;
207
208 ret = perf_trace_event_open(p_event);
209 if (ret) {
210 perf_trace_event_unreg(p_event);
211 return ret;
212 }
213
214 return 0;
215}
216
217int perf_trace_init(struct perf_event *p_event)
218{
219 struct trace_event_call *tp_event;
220 u64 event_id = p_event->attr.config;
221 int ret = -EINVAL;
222
223 mutex_lock(&event_mutex);
224 list_for_each_entry(tp_event, &ftrace_events, list) {
225 if (tp_event->event.type == event_id &&
226 tp_event->class && tp_event->class->reg &&
227 try_module_get(tp_event->mod)) {
228 ret = perf_trace_event_init(tp_event, p_event);
229 if (ret)
230 module_put(tp_event->mod);
231 break;
232 }
233 }
234 mutex_unlock(&event_mutex);
235
236 return ret;
237}
238
239void perf_trace_destroy(struct perf_event *p_event)
240{
241 mutex_lock(&event_mutex);
242 perf_trace_event_close(p_event);
243 perf_trace_event_unreg(p_event);
244 mutex_unlock(&event_mutex);
245}
246
247#ifdef CONFIG_KPROBE_EVENTS
248int perf_kprobe_init(struct perf_event *p_event, bool is_retprobe)
249{
250 int ret;
251 char *func = NULL;
252 struct trace_event_call *tp_event;
253
254 if (p_event->attr.kprobe_func) {
255 func = kzalloc(KSYM_NAME_LEN, GFP_KERNEL);
256 if (!func)
257 return -ENOMEM;
258 ret = strncpy_from_user(
259 func, u64_to_user_ptr(p_event->attr.kprobe_func),
260 KSYM_NAME_LEN);
261 if (ret == KSYM_NAME_LEN)
262 ret = -E2BIG;
263 if (ret < 0)
264 goto out;
265
266 if (func[0] == '\0') {
267 kfree(func);
268 func = NULL;
269 }
270 }
271
272 tp_event = create_local_trace_kprobe(
273 func, (void *)(unsigned long)(p_event->attr.kprobe_addr),
274 p_event->attr.probe_offset, is_retprobe);
275 if (IS_ERR(tp_event)) {
276 ret = PTR_ERR(tp_event);
277 goto out;
278 }
279
280 mutex_lock(&event_mutex);
281 ret = perf_trace_event_init(tp_event, p_event);
282 if (ret)
283 destroy_local_trace_kprobe(tp_event);
284 mutex_unlock(&event_mutex);
285out:
286 kfree(func);
287 return ret;
288}
289
290void perf_kprobe_destroy(struct perf_event *p_event)
291{
292 mutex_lock(&event_mutex);
293 perf_trace_event_close(p_event);
294 perf_trace_event_unreg(p_event);
295 mutex_unlock(&event_mutex);
296
297 destroy_local_trace_kprobe(p_event->tp_event);
298}
299#endif /* CONFIG_KPROBE_EVENTS */
300
301#ifdef CONFIG_UPROBE_EVENTS
302int perf_uprobe_init(struct perf_event *p_event,
303 unsigned long ref_ctr_offset, bool is_retprobe)
304{
305 int ret;
306 char *path = NULL;
307 struct trace_event_call *tp_event;
308
309 if (!p_event->attr.uprobe_path)
310 return -EINVAL;
311
312 path = strndup_user(u64_to_user_ptr(p_event->attr.uprobe_path),
313 PATH_MAX);
314 if (IS_ERR(path)) {
315 ret = PTR_ERR(path);
316 return (ret == -EINVAL) ? -E2BIG : ret;
317 }
318 if (path[0] == '\0') {
319 ret = -EINVAL;
320 goto out;
321 }
322
323 tp_event = create_local_trace_uprobe(path, p_event->attr.probe_offset,
324 ref_ctr_offset, is_retprobe);
325 if (IS_ERR(tp_event)) {
326 ret = PTR_ERR(tp_event);
327 goto out;
328 }
329
330 /*
331 * local trace_uprobe need to hold event_mutex to call
332 * uprobe_buffer_enable() and uprobe_buffer_disable().
333 * event_mutex is not required for local trace_kprobes.
334 */
335 mutex_lock(&event_mutex);
336 ret = perf_trace_event_init(tp_event, p_event);
337 if (ret)
338 destroy_local_trace_uprobe(tp_event);
339 mutex_unlock(&event_mutex);
340out:
341 kfree(path);
342 return ret;
343}
344
345void perf_uprobe_destroy(struct perf_event *p_event)
346{
347 mutex_lock(&event_mutex);
348 perf_trace_event_close(p_event);
349 perf_trace_event_unreg(p_event);
350 mutex_unlock(&event_mutex);
351 destroy_local_trace_uprobe(p_event->tp_event);
352}
353#endif /* CONFIG_UPROBE_EVENTS */
354
355int perf_trace_add(struct perf_event *p_event, int flags)
356{
357 struct trace_event_call *tp_event = p_event->tp_event;
358
359 if (!(flags & PERF_EF_START))
360 p_event->hw.state = PERF_HES_STOPPED;
361
362 /*
363 * If TRACE_REG_PERF_ADD returns false; no custom action was performed
364 * and we need to take the default action of enqueueing our event on
365 * the right per-cpu hlist.
366 */
367 if (!tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event)) {
368 struct hlist_head __percpu *pcpu_list;
369 struct hlist_head *list;
370
371 pcpu_list = tp_event->perf_events;
372 if (WARN_ON_ONCE(!pcpu_list))
373 return -EINVAL;
374
375 list = this_cpu_ptr(pcpu_list);
376 hlist_add_head_rcu(&p_event->hlist_entry, list);
377 }
378
379 return 0;
380}
381
382void perf_trace_del(struct perf_event *p_event, int flags)
383{
384 struct trace_event_call *tp_event = p_event->tp_event;
385
386 /*
387 * If TRACE_REG_PERF_DEL returns false; no custom action was performed
388 * and we need to take the default action of dequeueing our event from
389 * the right per-cpu hlist.
390 */
391 if (!tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event))
392 hlist_del_rcu(&p_event->hlist_entry);
393}
394
395void *perf_trace_buf_alloc(int size, struct pt_regs **regs, int *rctxp)
396{
397 char *raw_data;
398 int rctx;
399
400 BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
401
402 if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
403 "perf buffer not large enough"))
404 return NULL;
405
406 *rctxp = rctx = perf_swevent_get_recursion_context();
407 if (rctx < 0)
408 return NULL;
409
410 if (regs)
411 *regs = this_cpu_ptr(&__perf_regs[rctx]);
412 raw_data = this_cpu_ptr(perf_trace_buf[rctx]);
413
414 /* zero the dead bytes from align to not leak stack to user */
415 memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
416 return raw_data;
417}
418EXPORT_SYMBOL_GPL(perf_trace_buf_alloc);
419NOKPROBE_SYMBOL(perf_trace_buf_alloc);
420
421void perf_trace_buf_update(void *record, u16 type)
422{
423 struct trace_entry *entry = record;
424 int pc = preempt_count();
425 unsigned long flags;
426
427 local_save_flags(flags);
428 tracing_generic_entry_update(entry, type, flags, pc);
429}
430NOKPROBE_SYMBOL(perf_trace_buf_update);
431
432#ifdef CONFIG_FUNCTION_TRACER
433static void
434perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
435 struct ftrace_ops *ops, struct pt_regs *pt_regs)
436{
437 struct ftrace_entry *entry;
438 struct perf_event *event;
439 struct hlist_head head;
440 struct pt_regs regs;
441 int rctx;
442
443 if ((unsigned long)ops->private != smp_processor_id())
444 return;
445
446 event = container_of(ops, struct perf_event, ftrace_ops);
447
448 /*
449 * @event->hlist entry is NULL (per INIT_HLIST_NODE), and all
450 * the perf code does is hlist_for_each_entry_rcu(), so we can
451 * get away with simply setting the @head.first pointer in order
452 * to create a singular list.
453 */
454 head.first = &event->hlist_entry;
455
456#define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
457 sizeof(u64)) - sizeof(u32))
458
459 BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);
460
461 memset(®s, 0, sizeof(regs));
462 perf_fetch_caller_regs(®s);
463
464 entry = perf_trace_buf_alloc(ENTRY_SIZE, NULL, &rctx);
465 if (!entry)
466 return;
467
468 entry->ip = ip;
469 entry->parent_ip = parent_ip;
470 perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, TRACE_FN,
471 1, ®s, &head, NULL);
472
473#undef ENTRY_SIZE
474}
475
476static int perf_ftrace_function_register(struct perf_event *event)
477{
478 struct ftrace_ops *ops = &event->ftrace_ops;
479
480 ops->flags = FTRACE_OPS_FL_RCU;
481 ops->func = perf_ftrace_function_call;
482 ops->private = (void *)(unsigned long)nr_cpu_ids;
483
484 return register_ftrace_function(ops);
485}
486
487static int perf_ftrace_function_unregister(struct perf_event *event)
488{
489 struct ftrace_ops *ops = &event->ftrace_ops;
490 int ret = unregister_ftrace_function(ops);
491 ftrace_free_filter(ops);
492 return ret;
493}
494
495int perf_ftrace_event_register(struct trace_event_call *call,
496 enum trace_reg type, void *data)
497{
498 struct perf_event *event = data;
499
500 switch (type) {
501 case TRACE_REG_REGISTER:
502 case TRACE_REG_UNREGISTER:
503 break;
504 case TRACE_REG_PERF_REGISTER:
505 case TRACE_REG_PERF_UNREGISTER:
506 return 0;
507 case TRACE_REG_PERF_OPEN:
508 return perf_ftrace_function_register(data);
509 case TRACE_REG_PERF_CLOSE:
510 return perf_ftrace_function_unregister(data);
511 case TRACE_REG_PERF_ADD:
512 event->ftrace_ops.private = (void *)(unsigned long)smp_processor_id();
513 return 1;
514 case TRACE_REG_PERF_DEL:
515 event->ftrace_ops.private = (void *)(unsigned long)nr_cpu_ids;
516 return 1;
517 }
518
519 return -EINVAL;
520}
521#endif /* CONFIG_FUNCTION_TRACER */