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