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 * surprises 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 return; 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 } 179} 180 181static int perf_trace_event_open(struct perf_event *p_event) 182{ 183 struct trace_event_call *tp_event = p_event->tp_event; 184 return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event); 185} 186 187static void perf_trace_event_close(struct perf_event *p_event) 188{ 189 struct trace_event_call *tp_event = p_event->tp_event; 190 tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event); 191} 192 193static int perf_trace_event_init(struct trace_event_call *tp_event, 194 struct perf_event *p_event) 195{ 196 int ret; 197 198 ret = perf_trace_event_perm(tp_event, p_event); 199 if (ret) 200 return ret; 201 202 ret = perf_trace_event_reg(tp_event, p_event); 203 if (ret) 204 return ret; 205 206 ret = perf_trace_event_open(p_event); 207 if (ret) { 208 perf_trace_event_unreg(p_event); 209 return ret; 210 } 211 212 return 0; 213} 214 215int perf_trace_init(struct perf_event *p_event) 216{ 217 struct trace_event_call *tp_event; 218 u64 event_id = p_event->attr.config; 219 int ret = -EINVAL; 220 221 mutex_lock(&event_mutex); 222 list_for_each_entry(tp_event, &ftrace_events, list) { 223 if (tp_event->event.type == event_id && 224 tp_event->class && tp_event->class->reg && 225 trace_event_try_get_ref(tp_event)) { 226 ret = perf_trace_event_init(tp_event, p_event); 227 if (ret) 228 trace_event_put_ref(tp_event); 229 break; 230 } 231 } 232 mutex_unlock(&event_mutex); 233 234 return ret; 235} 236 237void perf_trace_destroy(struct perf_event *p_event) 238{ 239 mutex_lock(&event_mutex); 240 perf_trace_event_close(p_event); 241 perf_trace_event_unreg(p_event); 242 trace_event_put_ref(p_event->tp_event); 243 mutex_unlock(&event_mutex); 244} 245 246#ifdef CONFIG_KPROBE_EVENTS 247int perf_kprobe_init(struct perf_event *p_event, bool is_retprobe) 248{ 249 int ret; 250 char *func = NULL; 251 struct trace_event_call *tp_event; 252 253 if (p_event->attr.kprobe_func) { 254 func = strndup_user(u64_to_user_ptr(p_event->attr.kprobe_func), 255 KSYM_NAME_LEN); 256 if (IS_ERR(func)) { 257 ret = PTR_ERR(func); 258 return (ret == -EINVAL) ? -E2BIG : ret; 259 } 260 261 if (func[0] == '\0') { 262 kfree(func); 263 func = NULL; 264 } 265 } 266 267 tp_event = create_local_trace_kprobe( 268 func, (void *)(unsigned long)(p_event->attr.kprobe_addr), 269 p_event->attr.probe_offset, is_retprobe); 270 if (IS_ERR(tp_event)) { 271 ret = PTR_ERR(tp_event); 272 goto out; 273 } 274 275 mutex_lock(&event_mutex); 276 ret = perf_trace_event_init(tp_event, p_event); 277 if (ret) 278 destroy_local_trace_kprobe(tp_event); 279 mutex_unlock(&event_mutex); 280out: 281 kfree(func); 282 return ret; 283} 284 285void perf_kprobe_destroy(struct perf_event *p_event) 286{ 287 mutex_lock(&event_mutex); 288 perf_trace_event_close(p_event); 289 perf_trace_event_unreg(p_event); 290 trace_event_put_ref(p_event->tp_event); 291 mutex_unlock(&event_mutex); 292 293 destroy_local_trace_kprobe(p_event->tp_event); 294} 295#endif /* CONFIG_KPROBE_EVENTS */ 296 297#ifdef CONFIG_UPROBE_EVENTS 298int perf_uprobe_init(struct perf_event *p_event, 299 unsigned long ref_ctr_offset, bool is_retprobe) 300{ 301 int ret; 302 char *path = NULL; 303 struct trace_event_call *tp_event; 304 305 if (!p_event->attr.uprobe_path) 306 return -EINVAL; 307 308 path = strndup_user(u64_to_user_ptr(p_event->attr.uprobe_path), 309 PATH_MAX); 310 if (IS_ERR(path)) { 311 ret = PTR_ERR(path); 312 return (ret == -EINVAL) ? -E2BIG : ret; 313 } 314 if (path[0] == '\0') { 315 ret = -EINVAL; 316 goto out; 317 } 318 319 tp_event = create_local_trace_uprobe(path, p_event->attr.probe_offset, 320 ref_ctr_offset, is_retprobe); 321 if (IS_ERR(tp_event)) { 322 ret = PTR_ERR(tp_event); 323 goto out; 324 } 325 326 /* 327 * local trace_uprobe need to hold event_mutex to call 328 * uprobe_buffer_enable() and uprobe_buffer_disable(). 329 * event_mutex is not required for local trace_kprobes. 330 */ 331 mutex_lock(&event_mutex); 332 ret = perf_trace_event_init(tp_event, p_event); 333 if (ret) 334 destroy_local_trace_uprobe(tp_event); 335 mutex_unlock(&event_mutex); 336out: 337 kfree(path); 338 return ret; 339} 340 341void perf_uprobe_destroy(struct perf_event *p_event) 342{ 343 mutex_lock(&event_mutex); 344 perf_trace_event_close(p_event); 345 perf_trace_event_unreg(p_event); 346 trace_event_put_ref(p_event->tp_event); 347 mutex_unlock(&event_mutex); 348 destroy_local_trace_uprobe(p_event->tp_event); 349} 350#endif /* CONFIG_UPROBE_EVENTS */ 351 352int perf_trace_add(struct perf_event *p_event, int flags) 353{ 354 struct trace_event_call *tp_event = p_event->tp_event; 355 356 if (!(flags & PERF_EF_START)) 357 p_event->hw.state = PERF_HES_STOPPED; 358 359 /* 360 * If TRACE_REG_PERF_ADD returns false; no custom action was performed 361 * and we need to take the default action of enqueueing our event on 362 * the right per-cpu hlist. 363 */ 364 if (!tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event)) { 365 struct hlist_head __percpu *pcpu_list; 366 struct hlist_head *list; 367 368 pcpu_list = tp_event->perf_events; 369 if (WARN_ON_ONCE(!pcpu_list)) 370 return -EINVAL; 371 372 list = this_cpu_ptr(pcpu_list); 373 hlist_add_head_rcu(&p_event->hlist_entry, list); 374 } 375 376 return 0; 377} 378 379void perf_trace_del(struct perf_event *p_event, int flags) 380{ 381 struct trace_event_call *tp_event = p_event->tp_event; 382 383 /* 384 * If TRACE_REG_PERF_DEL returns false; no custom action was performed 385 * and we need to take the default action of dequeueing our event from 386 * the right per-cpu hlist. 387 */ 388 if (!tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event)) 389 hlist_del_rcu(&p_event->hlist_entry); 390} 391 392void *perf_trace_buf_alloc(int size, struct pt_regs **regs, int *rctxp) 393{ 394 char *raw_data; 395 int rctx; 396 397 BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long)); 398 399 if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, 400 "perf buffer not large enough, wanted %d, have %d", 401 size, PERF_MAX_TRACE_SIZE)) 402 return NULL; 403 404 *rctxp = rctx = perf_swevent_get_recursion_context(); 405 if (rctx < 0) 406 return NULL; 407 408 if (regs) 409 *regs = this_cpu_ptr(&__perf_regs[rctx]); 410 raw_data = this_cpu_ptr(perf_trace_buf[rctx]); 411 412 /* zero the dead bytes from align to not leak stack to user */ 413 memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64)); 414 return raw_data; 415} 416EXPORT_SYMBOL_GPL(perf_trace_buf_alloc); 417NOKPROBE_SYMBOL(perf_trace_buf_alloc); 418 419void perf_trace_buf_update(void *record, u16 type) 420{ 421 struct trace_entry *entry = record; 422 423 tracing_generic_entry_update(entry, type, tracing_gen_ctx()); 424} 425NOKPROBE_SYMBOL(perf_trace_buf_update); 426 427#ifdef CONFIG_FUNCTION_TRACER 428static void 429perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip, 430 struct ftrace_ops *ops, struct ftrace_regs *fregs) 431{ 432 struct ftrace_entry *entry; 433 struct perf_event *event; 434 struct hlist_head head; 435 struct pt_regs regs; 436 int rctx; 437 int bit; 438 439 if (!rcu_is_watching()) 440 return; 441 442 bit = ftrace_test_recursion_trylock(ip, parent_ip); 443 if (bit < 0) 444 return; 445 446 if ((unsigned long)ops->private != smp_processor_id()) 447 goto out; 448 449 event = container_of(ops, struct perf_event, ftrace_ops); 450 451 /* 452 * @event->hlist entry is NULL (per INIT_HLIST_NODE), and all 453 * the perf code does is hlist_for_each_entry_rcu(), so we can 454 * get away with simply setting the @head.first pointer in order 455 * to create a singular list. 456 */ 457 head.first = &event->hlist_entry; 458 459#define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \ 460 sizeof(u64)) - sizeof(u32)) 461 462 BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE); 463 464 memset(®s, 0, sizeof(regs)); 465 perf_fetch_caller_regs(®s); 466 467 entry = perf_trace_buf_alloc(ENTRY_SIZE, NULL, &rctx); 468 if (!entry) 469 goto out; 470 471 entry->ip = ip; 472 entry->parent_ip = parent_ip; 473 perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, TRACE_FN, 474 1, ®s, &head, NULL); 475 476out: 477 ftrace_test_recursion_unlock(bit); 478#undef ENTRY_SIZE 479} 480 481static int perf_ftrace_function_register(struct perf_event *event) 482{ 483 struct ftrace_ops *ops = &event->ftrace_ops; 484 485 ops->func = perf_ftrace_function_call; 486 ops->private = (void *)(unsigned long)nr_cpu_ids; 487 488 return register_ftrace_function(ops); 489} 490 491static int perf_ftrace_function_unregister(struct perf_event *event) 492{ 493 struct ftrace_ops *ops = &event->ftrace_ops; 494 int ret = unregister_ftrace_function(ops); 495 ftrace_free_filter(ops); 496 return ret; 497} 498 499int perf_ftrace_event_register(struct trace_event_call *call, 500 enum trace_reg type, void *data) 501{ 502 struct perf_event *event = data; 503 504 switch (type) { 505 case TRACE_REG_REGISTER: 506 case TRACE_REG_UNREGISTER: 507 break; 508 case TRACE_REG_PERF_REGISTER: 509 case TRACE_REG_PERF_UNREGISTER: 510 return 0; 511 case TRACE_REG_PERF_OPEN: 512 return perf_ftrace_function_register(data); 513 case TRACE_REG_PERF_CLOSE: 514 return perf_ftrace_function_unregister(data); 515 case TRACE_REG_PERF_ADD: 516 event->ftrace_ops.private = (void *)(unsigned long)smp_processor_id(); 517 return 1; 518 case TRACE_REG_PERF_DEL: 519 event->ftrace_ops.private = (void *)(unsigned long)nr_cpu_ids; 520 return 1; 521 } 522 523 return -EINVAL; 524} 525#endif /* CONFIG_FUNCTION_TRACER */ 526