1 // SPDX-License-Identifier: GPL-2.0 2 #include "util/cgroup.h" 3 #include "util/debug.h" 4 #include "util/evlist.h" 5 #include "util/hashmap.h" 6 #include "util/machine.h" 7 #include "util/map.h" 8 #include "util/symbol.h" 9 #include "util/target.h" 10 #include "util/thread.h" 11 #include "util/thread_map.h" 12 #include "util/lock-contention.h" 13 #include <linux/zalloc.h> 14 #include <linux/string.h> 15 #include <bpf/bpf.h> 16 #include <bpf/btf.h> 17 #include <inttypes.h> 18 19 #include "bpf_skel/lock_contention.skel.h" 20 #include "bpf_skel/lock_data.h" 21 22 static struct lock_contention_bpf *skel; 23 static bool has_slab_iter; 24 static struct hashmap slab_hash; 25 26 static size_t slab_cache_hash(long key, void *ctx __maybe_unused) 27 { 28 return key; 29 } 30 31 static bool slab_cache_equal(long key1, long key2, void *ctx __maybe_unused) 32 { 33 return key1 == key2; 34 } 35 36 static void check_slab_cache_iter(struct lock_contention *con) 37 { 38 struct btf *btf = btf__load_vmlinux_btf(); 39 s32 ret; 40 41 hashmap__init(&slab_hash, slab_cache_hash, slab_cache_equal, /*ctx=*/NULL); 42 43 if (btf == NULL) { 44 pr_debug("BTF loading failed: %s\n", strerror(errno)); 45 return; 46 } 47 48 ret = btf__find_by_name_kind(btf, "bpf_iter__kmem_cache", BTF_KIND_STRUCT); 49 if (ret < 0) { 50 bpf_program__set_autoload(skel->progs.slab_cache_iter, false); 51 pr_debug("slab cache iterator is not available: %d\n", ret); 52 goto out; 53 } 54 55 has_slab_iter = true; 56 57 bpf_map__set_max_entries(skel->maps.slab_caches, con->map_nr_entries); 58 out: 59 btf__free(btf); 60 } 61 62 static void run_slab_cache_iter(void) 63 { 64 int fd; 65 char buf[256]; 66 long key, *prev_key; 67 68 if (!has_slab_iter) 69 return; 70 71 fd = bpf_iter_create(bpf_link__fd(skel->links.slab_cache_iter)); 72 if (fd < 0) { 73 pr_debug("cannot create slab cache iter: %d\n", fd); 74 return; 75 } 76 77 /* This will run the bpf program */ 78 while (read(fd, buf, sizeof(buf)) > 0) 79 continue; 80 81 close(fd); 82 83 /* Read the slab cache map and build a hash with IDs */ 84 fd = bpf_map__fd(skel->maps.slab_caches); 85 prev_key = NULL; 86 while (!bpf_map_get_next_key(fd, prev_key, &key)) { 87 struct slab_cache_data *data; 88 89 data = malloc(sizeof(*data)); 90 if (data == NULL) 91 break; 92 93 if (bpf_map_lookup_elem(fd, &key, data) < 0) 94 break; 95 96 hashmap__add(&slab_hash, data->id, data); 97 prev_key = &key; 98 } 99 } 100 101 static void exit_slab_cache_iter(void) 102 { 103 struct hashmap_entry *cur; 104 unsigned bkt; 105 106 hashmap__for_each_entry(&slab_hash, cur, bkt) 107 free(cur->pvalue); 108 109 hashmap__clear(&slab_hash); 110 } 111 112 int lock_contention_prepare(struct lock_contention *con) 113 { 114 int i, fd; 115 int ncpus = 1, ntasks = 1, ntypes = 1, naddrs = 1, ncgrps = 1, nslabs = 1; 116 struct evlist *evlist = con->evlist; 117 struct target *target = con->target; 118 119 skel = lock_contention_bpf__open(); 120 if (!skel) { 121 pr_err("Failed to open lock-contention BPF skeleton\n"); 122 return -1; 123 } 124 125 bpf_map__set_value_size(skel->maps.stacks, con->max_stack * sizeof(u64)); 126 bpf_map__set_max_entries(skel->maps.lock_stat, con->map_nr_entries); 127 bpf_map__set_max_entries(skel->maps.tstamp, con->map_nr_entries); 128 129 if (con->aggr_mode == LOCK_AGGR_TASK) 130 bpf_map__set_max_entries(skel->maps.task_data, con->map_nr_entries); 131 else 132 bpf_map__set_max_entries(skel->maps.task_data, 1); 133 134 if (con->save_callstack) 135 bpf_map__set_max_entries(skel->maps.stacks, con->map_nr_entries); 136 else 137 bpf_map__set_max_entries(skel->maps.stacks, 1); 138 139 if (target__has_cpu(target)) { 140 skel->rodata->has_cpu = 1; 141 ncpus = perf_cpu_map__nr(evlist->core.user_requested_cpus); 142 } 143 if (target__has_task(target)) { 144 skel->rodata->has_task = 1; 145 ntasks = perf_thread_map__nr(evlist->core.threads); 146 } 147 if (con->filters->nr_types) { 148 skel->rodata->has_type = 1; 149 ntypes = con->filters->nr_types; 150 } 151 if (con->filters->nr_cgrps) { 152 skel->rodata->has_cgroup = 1; 153 ncgrps = con->filters->nr_cgrps; 154 } 155 156 /* resolve lock name filters to addr */ 157 if (con->filters->nr_syms) { 158 struct symbol *sym; 159 struct map *kmap; 160 unsigned long *addrs; 161 162 for (i = 0; i < con->filters->nr_syms; i++) { 163 sym = machine__find_kernel_symbol_by_name(con->machine, 164 con->filters->syms[i], 165 &kmap); 166 if (sym == NULL) { 167 pr_warning("ignore unknown symbol: %s\n", 168 con->filters->syms[i]); 169 continue; 170 } 171 172 addrs = realloc(con->filters->addrs, 173 (con->filters->nr_addrs + 1) * sizeof(*addrs)); 174 if (addrs == NULL) { 175 pr_warning("memory allocation failure\n"); 176 continue; 177 } 178 179 addrs[con->filters->nr_addrs++] = map__unmap_ip(kmap, sym->start); 180 con->filters->addrs = addrs; 181 } 182 naddrs = con->filters->nr_addrs; 183 skel->rodata->has_addr = 1; 184 } 185 186 bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus); 187 bpf_map__set_max_entries(skel->maps.task_filter, ntasks); 188 bpf_map__set_max_entries(skel->maps.type_filter, ntypes); 189 bpf_map__set_max_entries(skel->maps.addr_filter, naddrs); 190 bpf_map__set_max_entries(skel->maps.cgroup_filter, ncgrps); 191 192 skel->rodata->stack_skip = con->stack_skip; 193 skel->rodata->aggr_mode = con->aggr_mode; 194 skel->rodata->needs_callstack = con->save_callstack; 195 skel->rodata->lock_owner = con->owner; 196 197 if (con->aggr_mode == LOCK_AGGR_CGROUP || con->filters->nr_cgrps) { 198 if (cgroup_is_v2("perf_event")) 199 skel->rodata->use_cgroup_v2 = 1; 200 } 201 202 check_slab_cache_iter(con); 203 204 if (con->filters->nr_slabs && has_slab_iter) { 205 skel->rodata->has_slab = 1; 206 nslabs = con->filters->nr_slabs; 207 } 208 209 bpf_map__set_max_entries(skel->maps.slab_filter, nslabs); 210 211 if (lock_contention_bpf__load(skel) < 0) { 212 pr_err("Failed to load lock-contention BPF skeleton\n"); 213 return -1; 214 } 215 216 if (target__has_cpu(target)) { 217 u32 cpu; 218 u8 val = 1; 219 220 fd = bpf_map__fd(skel->maps.cpu_filter); 221 222 for (i = 0; i < ncpus; i++) { 223 cpu = perf_cpu_map__cpu(evlist->core.user_requested_cpus, i).cpu; 224 bpf_map_update_elem(fd, &cpu, &val, BPF_ANY); 225 } 226 } 227 228 if (target__has_task(target)) { 229 u32 pid; 230 u8 val = 1; 231 232 fd = bpf_map__fd(skel->maps.task_filter); 233 234 for (i = 0; i < ntasks; i++) { 235 pid = perf_thread_map__pid(evlist->core.threads, i); 236 bpf_map_update_elem(fd, &pid, &val, BPF_ANY); 237 } 238 } 239 240 if (target__none(target) && evlist->workload.pid > 0) { 241 u32 pid = evlist->workload.pid; 242 u8 val = 1; 243 244 fd = bpf_map__fd(skel->maps.task_filter); 245 bpf_map_update_elem(fd, &pid, &val, BPF_ANY); 246 } 247 248 if (con->filters->nr_types) { 249 u8 val = 1; 250 251 fd = bpf_map__fd(skel->maps.type_filter); 252 253 for (i = 0; i < con->filters->nr_types; i++) 254 bpf_map_update_elem(fd, &con->filters->types[i], &val, BPF_ANY); 255 } 256 257 if (con->filters->nr_addrs) { 258 u8 val = 1; 259 260 fd = bpf_map__fd(skel->maps.addr_filter); 261 262 for (i = 0; i < con->filters->nr_addrs; i++) 263 bpf_map_update_elem(fd, &con->filters->addrs[i], &val, BPF_ANY); 264 } 265 266 if (con->filters->nr_cgrps) { 267 u8 val = 1; 268 269 fd = bpf_map__fd(skel->maps.cgroup_filter); 270 271 for (i = 0; i < con->filters->nr_cgrps; i++) 272 bpf_map_update_elem(fd, &con->filters->cgrps[i], &val, BPF_ANY); 273 } 274 275 if (con->aggr_mode == LOCK_AGGR_CGROUP) 276 read_all_cgroups(&con->cgroups); 277 278 bpf_program__set_autoload(skel->progs.collect_lock_syms, false); 279 280 lock_contention_bpf__attach(skel); 281 282 /* run the slab iterator after attaching */ 283 run_slab_cache_iter(); 284 285 if (con->filters->nr_slabs) { 286 u8 val = 1; 287 int cache_fd; 288 long key, *prev_key; 289 290 fd = bpf_map__fd(skel->maps.slab_filter); 291 292 /* Read the slab cache map and build a hash with its address */ 293 cache_fd = bpf_map__fd(skel->maps.slab_caches); 294 prev_key = NULL; 295 while (!bpf_map_get_next_key(cache_fd, prev_key, &key)) { 296 struct slab_cache_data data; 297 298 if (bpf_map_lookup_elem(cache_fd, &key, &data) < 0) 299 break; 300 301 for (i = 0; i < con->filters->nr_slabs; i++) { 302 if (!strcmp(con->filters->slabs[i], data.name)) { 303 bpf_map_update_elem(fd, &key, &val, BPF_ANY); 304 break; 305 } 306 } 307 prev_key = &key; 308 } 309 } 310 311 return 0; 312 } 313 314 /* 315 * Run the BPF program directly using BPF_PROG_TEST_RUN to update the end 316 * timestamp in ktime so that it can calculate delta easily. 317 */ 318 static void mark_end_timestamp(void) 319 { 320 DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts, 321 .flags = BPF_F_TEST_RUN_ON_CPU, 322 ); 323 int prog_fd = bpf_program__fd(skel->progs.end_timestamp); 324 325 bpf_prog_test_run_opts(prog_fd, &opts); 326 } 327 328 static void update_lock_stat(int map_fd, int pid, u64 end_ts, 329 enum lock_aggr_mode aggr_mode, 330 struct tstamp_data *ts_data) 331 { 332 u64 delta; 333 struct contention_key stat_key = {}; 334 struct contention_data stat_data; 335 336 if (ts_data->timestamp >= end_ts) 337 return; 338 339 delta = end_ts - ts_data->timestamp; 340 341 switch (aggr_mode) { 342 case LOCK_AGGR_CALLER: 343 stat_key.stack_id = ts_data->stack_id; 344 break; 345 case LOCK_AGGR_TASK: 346 stat_key.pid = pid; 347 break; 348 case LOCK_AGGR_ADDR: 349 stat_key.lock_addr_or_cgroup = ts_data->lock; 350 break; 351 case LOCK_AGGR_CGROUP: 352 /* TODO */ 353 return; 354 default: 355 return; 356 } 357 358 if (bpf_map_lookup_elem(map_fd, &stat_key, &stat_data) < 0) 359 return; 360 361 stat_data.total_time += delta; 362 stat_data.count++; 363 364 if (delta > stat_data.max_time) 365 stat_data.max_time = delta; 366 if (delta < stat_data.min_time) 367 stat_data.min_time = delta; 368 369 bpf_map_update_elem(map_fd, &stat_key, &stat_data, BPF_EXIST); 370 } 371 372 /* 373 * Account entries in the tstamp map (which didn't see the corresponding 374 * lock:contention_end tracepoint) using end_ts. 375 */ 376 static void account_end_timestamp(struct lock_contention *con) 377 { 378 int ts_fd, stat_fd; 379 int *prev_key, key; 380 u64 end_ts = skel->bss->end_ts; 381 int total_cpus; 382 enum lock_aggr_mode aggr_mode = con->aggr_mode; 383 struct tstamp_data ts_data, *cpu_data; 384 385 /* Iterate per-task tstamp map (key = TID) */ 386 ts_fd = bpf_map__fd(skel->maps.tstamp); 387 stat_fd = bpf_map__fd(skel->maps.lock_stat); 388 389 prev_key = NULL; 390 while (!bpf_map_get_next_key(ts_fd, prev_key, &key)) { 391 if (bpf_map_lookup_elem(ts_fd, &key, &ts_data) == 0) { 392 int pid = key; 393 394 if (aggr_mode == LOCK_AGGR_TASK && con->owner) 395 pid = ts_data.flags; 396 397 update_lock_stat(stat_fd, pid, end_ts, aggr_mode, 398 &ts_data); 399 } 400 401 prev_key = &key; 402 } 403 404 /* Now it'll check per-cpu tstamp map which doesn't have TID. */ 405 if (aggr_mode == LOCK_AGGR_TASK || aggr_mode == LOCK_AGGR_CGROUP) 406 return; 407 408 total_cpus = cpu__max_cpu().cpu; 409 ts_fd = bpf_map__fd(skel->maps.tstamp_cpu); 410 411 cpu_data = calloc(total_cpus, sizeof(*cpu_data)); 412 if (cpu_data == NULL) 413 return; 414 415 prev_key = NULL; 416 while (!bpf_map_get_next_key(ts_fd, prev_key, &key)) { 417 if (bpf_map_lookup_elem(ts_fd, &key, cpu_data) < 0) 418 goto next; 419 420 for (int i = 0; i < total_cpus; i++) { 421 if (cpu_data[i].lock == 0) 422 continue; 423 424 update_lock_stat(stat_fd, -1, end_ts, aggr_mode, 425 &cpu_data[i]); 426 } 427 428 next: 429 prev_key = &key; 430 } 431 free(cpu_data); 432 } 433 434 int lock_contention_start(void) 435 { 436 skel->bss->enabled = 1; 437 return 0; 438 } 439 440 int lock_contention_stop(void) 441 { 442 skel->bss->enabled = 0; 443 mark_end_timestamp(); 444 return 0; 445 } 446 447 static const char *lock_contention_get_name(struct lock_contention *con, 448 struct contention_key *key, 449 u64 *stack_trace, u32 flags) 450 { 451 int idx = 0; 452 u64 addr; 453 const char *name = ""; 454 static char name_buf[KSYM_NAME_LEN]; 455 struct symbol *sym; 456 struct map *kmap; 457 struct machine *machine = con->machine; 458 459 if (con->aggr_mode == LOCK_AGGR_TASK) { 460 struct contention_task_data task; 461 int pid = key->pid; 462 int task_fd = bpf_map__fd(skel->maps.task_data); 463 464 /* do not update idle comm which contains CPU number */ 465 if (pid) { 466 struct thread *t = machine__findnew_thread(machine, /*pid=*/-1, pid); 467 468 if (t == NULL) 469 return name; 470 if (!bpf_map_lookup_elem(task_fd, &pid, &task) && 471 thread__set_comm(t, task.comm, /*timestamp=*/0)) 472 name = task.comm; 473 } 474 return name; 475 } 476 477 if (con->aggr_mode == LOCK_AGGR_ADDR) { 478 int lock_fd = bpf_map__fd(skel->maps.lock_syms); 479 struct slab_cache_data *slab_data; 480 481 /* per-process locks set upper bits of the flags */ 482 if (flags & LCD_F_MMAP_LOCK) 483 return "mmap_lock"; 484 if (flags & LCD_F_SIGHAND_LOCK) 485 return "siglock"; 486 487 /* global locks with symbols */ 488 sym = machine__find_kernel_symbol(machine, key->lock_addr_or_cgroup, &kmap); 489 if (sym) 490 return sym->name; 491 492 /* try semi-global locks collected separately */ 493 if (!bpf_map_lookup_elem(lock_fd, &key->lock_addr_or_cgroup, &flags)) { 494 if (flags == LOCK_CLASS_RQLOCK) 495 return "rq_lock"; 496 } 497 498 /* look slab_hash for dynamic locks in a slab object */ 499 if (hashmap__find(&slab_hash, flags & LCB_F_SLAB_ID_MASK, &slab_data)) { 500 snprintf(name_buf, sizeof(name_buf), "&%s", slab_data->name); 501 return name_buf; 502 } 503 504 return ""; 505 } 506 507 if (con->aggr_mode == LOCK_AGGR_CGROUP) { 508 u64 cgrp_id = key->lock_addr_or_cgroup; 509 struct cgroup *cgrp = __cgroup__find(&con->cgroups, cgrp_id); 510 511 if (cgrp) 512 return cgrp->name; 513 514 snprintf(name_buf, sizeof(name_buf), "cgroup:%" PRIu64 "", cgrp_id); 515 return name_buf; 516 } 517 518 /* LOCK_AGGR_CALLER: skip lock internal functions */ 519 while (machine__is_lock_function(machine, stack_trace[idx]) && 520 idx < con->max_stack - 1) 521 idx++; 522 523 addr = stack_trace[idx]; 524 sym = machine__find_kernel_symbol(machine, addr, &kmap); 525 526 if (sym) { 527 unsigned long offset; 528 529 offset = map__map_ip(kmap, addr) - sym->start; 530 531 if (offset == 0) 532 return sym->name; 533 534 snprintf(name_buf, sizeof(name_buf), "%s+%#lx", sym->name, offset); 535 } else { 536 snprintf(name_buf, sizeof(name_buf), "%#lx", (unsigned long)addr); 537 } 538 539 return name_buf; 540 } 541 542 int lock_contention_read(struct lock_contention *con) 543 { 544 int fd, stack, err = 0; 545 struct contention_key *prev_key, key = {}; 546 struct contention_data data = {}; 547 struct lock_stat *st = NULL; 548 struct machine *machine = con->machine; 549 u64 *stack_trace; 550 size_t stack_size = con->max_stack * sizeof(*stack_trace); 551 552 fd = bpf_map__fd(skel->maps.lock_stat); 553 stack = bpf_map__fd(skel->maps.stacks); 554 555 con->fails.task = skel->bss->task_fail; 556 con->fails.stack = skel->bss->stack_fail; 557 con->fails.time = skel->bss->time_fail; 558 con->fails.data = skel->bss->data_fail; 559 560 stack_trace = zalloc(stack_size); 561 if (stack_trace == NULL) 562 return -1; 563 564 account_end_timestamp(con); 565 566 if (con->aggr_mode == LOCK_AGGR_TASK) { 567 struct thread *idle = machine__findnew_thread(machine, 568 /*pid=*/0, 569 /*tid=*/0); 570 thread__set_comm(idle, "swapper", /*timestamp=*/0); 571 } 572 573 if (con->aggr_mode == LOCK_AGGR_ADDR) { 574 DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts, 575 .flags = BPF_F_TEST_RUN_ON_CPU, 576 ); 577 int prog_fd = bpf_program__fd(skel->progs.collect_lock_syms); 578 579 bpf_prog_test_run_opts(prog_fd, &opts); 580 } 581 582 /* make sure it loads the kernel map */ 583 maps__load_first(machine->kmaps); 584 585 prev_key = NULL; 586 while (!bpf_map_get_next_key(fd, prev_key, &key)) { 587 s64 ls_key; 588 const char *name; 589 590 /* to handle errors in the loop body */ 591 err = -1; 592 593 bpf_map_lookup_elem(fd, &key, &data); 594 if (con->save_callstack) { 595 bpf_map_lookup_elem(stack, &key.stack_id, stack_trace); 596 597 if (!match_callstack_filter(machine, stack_trace, con->max_stack)) { 598 con->nr_filtered += data.count; 599 goto next; 600 } 601 } 602 603 switch (con->aggr_mode) { 604 case LOCK_AGGR_CALLER: 605 ls_key = key.stack_id; 606 break; 607 case LOCK_AGGR_TASK: 608 ls_key = key.pid; 609 break; 610 case LOCK_AGGR_ADDR: 611 case LOCK_AGGR_CGROUP: 612 ls_key = key.lock_addr_or_cgroup; 613 break; 614 default: 615 goto next; 616 } 617 618 st = lock_stat_find(ls_key); 619 if (st != NULL) { 620 st->wait_time_total += data.total_time; 621 if (st->wait_time_max < data.max_time) 622 st->wait_time_max = data.max_time; 623 if (st->wait_time_min > data.min_time) 624 st->wait_time_min = data.min_time; 625 626 st->nr_contended += data.count; 627 if (st->nr_contended) 628 st->avg_wait_time = st->wait_time_total / st->nr_contended; 629 goto next; 630 } 631 632 name = lock_contention_get_name(con, &key, stack_trace, data.flags); 633 st = lock_stat_findnew(ls_key, name, data.flags); 634 if (st == NULL) 635 break; 636 637 st->nr_contended = data.count; 638 st->wait_time_total = data.total_time; 639 st->wait_time_max = data.max_time; 640 st->wait_time_min = data.min_time; 641 642 if (data.count) 643 st->avg_wait_time = data.total_time / data.count; 644 645 if (con->aggr_mode == LOCK_AGGR_CALLER && verbose > 0) { 646 st->callstack = memdup(stack_trace, stack_size); 647 if (st->callstack == NULL) 648 break; 649 } 650 651 next: 652 prev_key = &key; 653 654 /* we're fine now, reset the error */ 655 err = 0; 656 } 657 658 free(stack_trace); 659 660 return err; 661 } 662 663 int lock_contention_finish(struct lock_contention *con) 664 { 665 if (skel) { 666 skel->bss->enabled = 0; 667 lock_contention_bpf__destroy(skel); 668 } 669 670 while (!RB_EMPTY_ROOT(&con->cgroups)) { 671 struct rb_node *node = rb_first(&con->cgroups); 672 struct cgroup *cgrp = rb_entry(node, struct cgroup, node); 673 674 rb_erase(node, &con->cgroups); 675 cgroup__put(cgrp); 676 } 677 678 exit_slab_cache_iter(); 679 680 return 0; 681 } 682