1 // SPDX-License-Identifier: GPL-2.0-only 2 /* Copyright (c) 2016 Facebook 3 */ 4 #include <linux/bpf.h> 5 #include <linux/jhash.h> 6 #include <linux/filter.h> 7 #include <linux/kernel.h> 8 #include <linux/stacktrace.h> 9 #include <linux/perf_event.h> 10 #include <linux/btf_ids.h> 11 #include <linux/buildid.h> 12 #include "percpu_freelist.h" 13 #include "mmap_unlock_work.h" 14 15 #define STACK_CREATE_FLAG_MASK \ 16 (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY | \ 17 BPF_F_STACK_BUILD_ID) 18 19 struct stack_map_bucket { 20 struct pcpu_freelist_node fnode; 21 u32 hash; 22 u32 nr; 23 u64 data[]; 24 }; 25 26 struct bpf_stack_map { 27 struct bpf_map map; 28 void *elems; 29 struct pcpu_freelist freelist; 30 u32 n_buckets; 31 struct stack_map_bucket *buckets[] __counted_by(n_buckets); 32 }; 33 34 static inline bool stack_map_use_build_id(struct bpf_map *map) 35 { 36 return (map->map_flags & BPF_F_STACK_BUILD_ID); 37 } 38 39 static inline int stack_map_data_size(struct bpf_map *map) 40 { 41 return stack_map_use_build_id(map) ? 42 sizeof(struct bpf_stack_build_id) : sizeof(u64); 43 } 44 45 static int prealloc_elems_and_freelist(struct bpf_stack_map *smap) 46 { 47 u64 elem_size = sizeof(struct stack_map_bucket) + 48 (u64)smap->map.value_size; 49 int err; 50 51 smap->elems = bpf_map_area_alloc(elem_size * smap->map.max_entries, 52 smap->map.numa_node); 53 if (!smap->elems) 54 return -ENOMEM; 55 56 err = pcpu_freelist_init(&smap->freelist); 57 if (err) 58 goto free_elems; 59 60 pcpu_freelist_populate(&smap->freelist, smap->elems, elem_size, 61 smap->map.max_entries); 62 return 0; 63 64 free_elems: 65 bpf_map_area_free(smap->elems); 66 return err; 67 } 68 69 /* Called from syscall */ 70 static struct bpf_map *stack_map_alloc(union bpf_attr *attr) 71 { 72 u32 value_size = attr->value_size; 73 struct bpf_stack_map *smap; 74 u64 cost, n_buckets; 75 int err; 76 77 if (attr->map_flags & ~STACK_CREATE_FLAG_MASK) 78 return ERR_PTR(-EINVAL); 79 80 /* check sanity of attributes */ 81 if (attr->max_entries == 0 || attr->key_size != 4 || 82 value_size < 8 || value_size % 8) 83 return ERR_PTR(-EINVAL); 84 85 BUILD_BUG_ON(sizeof(struct bpf_stack_build_id) % sizeof(u64)); 86 if (attr->map_flags & BPF_F_STACK_BUILD_ID) { 87 if (value_size % sizeof(struct bpf_stack_build_id) || 88 value_size / sizeof(struct bpf_stack_build_id) 89 > sysctl_perf_event_max_stack) 90 return ERR_PTR(-EINVAL); 91 } else if (value_size / 8 > sysctl_perf_event_max_stack) 92 return ERR_PTR(-EINVAL); 93 94 /* hash table size must be power of 2; roundup_pow_of_two() can overflow 95 * into UB on 32-bit arches, so check that first 96 */ 97 if (attr->max_entries > 1UL << 31) 98 return ERR_PTR(-E2BIG); 99 100 n_buckets = roundup_pow_of_two(attr->max_entries); 101 102 cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap); 103 smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr)); 104 if (!smap) 105 return ERR_PTR(-ENOMEM); 106 107 bpf_map_init_from_attr(&smap->map, attr); 108 smap->n_buckets = n_buckets; 109 110 err = get_callchain_buffers(sysctl_perf_event_max_stack); 111 if (err) 112 goto free_smap; 113 114 err = prealloc_elems_and_freelist(smap); 115 if (err) 116 goto put_buffers; 117 118 return &smap->map; 119 120 put_buffers: 121 put_callchain_buffers(); 122 free_smap: 123 bpf_map_area_free(smap); 124 return ERR_PTR(err); 125 } 126 127 /* 128 * Expects all id_offs[i].ip values to be set to correct initial IPs. 129 * They will be subsequently: 130 * - either adjusted in place to a file offset, if build ID fetching 131 * succeeds; in this case id_offs[i].build_id is set to correct build ID, 132 * and id_offs[i].status is set to BPF_STACK_BUILD_ID_VALID; 133 * - or IP will be kept intact, if build ID fetching failed; in this case 134 * id_offs[i].build_id is zeroed out and id_offs[i].status is set to 135 * BPF_STACK_BUILD_ID_IP. 136 */ 137 static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, 138 u32 trace_nr, bool user) 139 { 140 int i; 141 struct mmap_unlock_irq_work *work = NULL; 142 bool irq_work_busy = bpf_mmap_unlock_get_irq_work(&work); 143 struct vm_area_struct *vma, *prev_vma = NULL; 144 const char *prev_build_id; 145 146 /* If the irq_work is in use, fall back to report ips. Same 147 * fallback is used for kernel stack (!user) on a stackmap with 148 * build_id. 149 */ 150 if (!user || !current || !current->mm || irq_work_busy || 151 !mmap_read_trylock(current->mm)) { 152 /* cannot access current->mm, fall back to ips */ 153 for (i = 0; i < trace_nr; i++) { 154 id_offs[i].status = BPF_STACK_BUILD_ID_IP; 155 memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX); 156 } 157 return; 158 } 159 160 for (i = 0; i < trace_nr; i++) { 161 u64 ip = READ_ONCE(id_offs[i].ip); 162 163 if (range_in_vma(prev_vma, ip, ip)) { 164 vma = prev_vma; 165 memcpy(id_offs[i].build_id, prev_build_id, BUILD_ID_SIZE_MAX); 166 goto build_id_valid; 167 } 168 vma = find_vma(current->mm, ip); 169 if (!vma || build_id_parse_nofault(vma, id_offs[i].build_id, NULL)) { 170 /* per entry fall back to ips */ 171 id_offs[i].status = BPF_STACK_BUILD_ID_IP; 172 memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX); 173 continue; 174 } 175 build_id_valid: 176 id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ip - vma->vm_start; 177 id_offs[i].status = BPF_STACK_BUILD_ID_VALID; 178 prev_vma = vma; 179 prev_build_id = id_offs[i].build_id; 180 } 181 bpf_mmap_unlock_mm(work, current->mm); 182 } 183 184 static struct perf_callchain_entry * 185 get_callchain_entry_for_task(struct task_struct *task, u32 max_depth) 186 { 187 #ifdef CONFIG_STACKTRACE 188 struct perf_callchain_entry *entry; 189 int rctx; 190 191 entry = get_callchain_entry(&rctx); 192 193 if (!entry) 194 return NULL; 195 196 entry->nr = stack_trace_save_tsk(task, (unsigned long *)entry->ip, 197 max_depth, 0); 198 199 /* stack_trace_save_tsk() works on unsigned long array, while 200 * perf_callchain_entry uses u64 array. For 32-bit systems, it is 201 * necessary to fix this mismatch. 202 */ 203 if (__BITS_PER_LONG != 64) { 204 unsigned long *from = (unsigned long *) entry->ip; 205 u64 *to = entry->ip; 206 int i; 207 208 /* copy data from the end to avoid using extra buffer */ 209 for (i = entry->nr - 1; i >= 0; i--) 210 to[i] = (u64)(from[i]); 211 } 212 213 put_callchain_entry(rctx); 214 215 return entry; 216 #else /* CONFIG_STACKTRACE */ 217 return NULL; 218 #endif 219 } 220 221 static long __bpf_get_stackid(struct bpf_map *map, 222 struct perf_callchain_entry *trace, u64 flags) 223 { 224 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); 225 struct stack_map_bucket *bucket, *new_bucket, *old_bucket; 226 u32 skip = flags & BPF_F_SKIP_FIELD_MASK; 227 u32 hash, id, trace_nr, trace_len, i; 228 bool user = flags & BPF_F_USER_STACK; 229 u64 *ips; 230 bool hash_matches; 231 232 if (trace->nr <= skip) 233 /* skipping more than usable stack trace */ 234 return -EFAULT; 235 236 trace_nr = trace->nr - skip; 237 trace_len = trace_nr * sizeof(u64); 238 ips = trace->ip + skip; 239 hash = jhash2((u32 *)ips, trace_len / sizeof(u32), 0); 240 id = hash & (smap->n_buckets - 1); 241 bucket = READ_ONCE(smap->buckets[id]); 242 243 hash_matches = bucket && bucket->hash == hash; 244 /* fast cmp */ 245 if (hash_matches && flags & BPF_F_FAST_STACK_CMP) 246 return id; 247 248 if (stack_map_use_build_id(map)) { 249 struct bpf_stack_build_id *id_offs; 250 251 /* for build_id+offset, pop a bucket before slow cmp */ 252 new_bucket = (struct stack_map_bucket *) 253 pcpu_freelist_pop(&smap->freelist); 254 if (unlikely(!new_bucket)) 255 return -ENOMEM; 256 new_bucket->nr = trace_nr; 257 id_offs = (struct bpf_stack_build_id *)new_bucket->data; 258 for (i = 0; i < trace_nr; i++) 259 id_offs[i].ip = ips[i]; 260 stack_map_get_build_id_offset(id_offs, trace_nr, user); 261 trace_len = trace_nr * sizeof(struct bpf_stack_build_id); 262 if (hash_matches && bucket->nr == trace_nr && 263 memcmp(bucket->data, new_bucket->data, trace_len) == 0) { 264 pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); 265 return id; 266 } 267 if (bucket && !(flags & BPF_F_REUSE_STACKID)) { 268 pcpu_freelist_push(&smap->freelist, &new_bucket->fnode); 269 return -EEXIST; 270 } 271 } else { 272 if (hash_matches && bucket->nr == trace_nr && 273 memcmp(bucket->data, ips, trace_len) == 0) 274 return id; 275 if (bucket && !(flags & BPF_F_REUSE_STACKID)) 276 return -EEXIST; 277 278 new_bucket = (struct stack_map_bucket *) 279 pcpu_freelist_pop(&smap->freelist); 280 if (unlikely(!new_bucket)) 281 return -ENOMEM; 282 memcpy(new_bucket->data, ips, trace_len); 283 } 284 285 new_bucket->hash = hash; 286 new_bucket->nr = trace_nr; 287 288 old_bucket = xchg(&smap->buckets[id], new_bucket); 289 if (old_bucket) 290 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); 291 return id; 292 } 293 294 BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map, 295 u64, flags) 296 { 297 u32 max_depth = map->value_size / stack_map_data_size(map); 298 u32 skip = flags & BPF_F_SKIP_FIELD_MASK; 299 bool user = flags & BPF_F_USER_STACK; 300 struct perf_callchain_entry *trace; 301 bool kernel = !user; 302 303 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | 304 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) 305 return -EINVAL; 306 307 max_depth += skip; 308 if (max_depth > sysctl_perf_event_max_stack) 309 max_depth = sysctl_perf_event_max_stack; 310 311 trace = get_perf_callchain(regs, 0, kernel, user, max_depth, 312 false, false); 313 314 if (unlikely(!trace)) 315 /* couldn't fetch the stack trace */ 316 return -EFAULT; 317 318 return __bpf_get_stackid(map, trace, flags); 319 } 320 321 const struct bpf_func_proto bpf_get_stackid_proto = { 322 .func = bpf_get_stackid, 323 .gpl_only = true, 324 .ret_type = RET_INTEGER, 325 .arg1_type = ARG_PTR_TO_CTX, 326 .arg2_type = ARG_CONST_MAP_PTR, 327 .arg3_type = ARG_ANYTHING, 328 }; 329 330 static __u64 count_kernel_ip(struct perf_callchain_entry *trace) 331 { 332 __u64 nr_kernel = 0; 333 334 while (nr_kernel < trace->nr) { 335 if (trace->ip[nr_kernel] == PERF_CONTEXT_USER) 336 break; 337 nr_kernel++; 338 } 339 return nr_kernel; 340 } 341 342 BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx, 343 struct bpf_map *, map, u64, flags) 344 { 345 struct perf_event *event = ctx->event; 346 struct perf_callchain_entry *trace; 347 bool kernel, user; 348 __u64 nr_kernel; 349 int ret; 350 351 /* perf_sample_data doesn't have callchain, use bpf_get_stackid */ 352 if (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)) 353 return bpf_get_stackid((unsigned long)(ctx->regs), 354 (unsigned long) map, flags, 0, 0); 355 356 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | 357 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID))) 358 return -EINVAL; 359 360 user = flags & BPF_F_USER_STACK; 361 kernel = !user; 362 363 trace = ctx->data->callchain; 364 if (unlikely(!trace)) 365 return -EFAULT; 366 367 nr_kernel = count_kernel_ip(trace); 368 369 if (kernel) { 370 __u64 nr = trace->nr; 371 372 trace->nr = nr_kernel; 373 ret = __bpf_get_stackid(map, trace, flags); 374 375 /* restore nr */ 376 trace->nr = nr; 377 } else { /* user */ 378 u64 skip = flags & BPF_F_SKIP_FIELD_MASK; 379 380 skip += nr_kernel; 381 if (skip > BPF_F_SKIP_FIELD_MASK) 382 return -EFAULT; 383 384 flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip; 385 ret = __bpf_get_stackid(map, trace, flags); 386 } 387 return ret; 388 } 389 390 const struct bpf_func_proto bpf_get_stackid_proto_pe = { 391 .func = bpf_get_stackid_pe, 392 .gpl_only = false, 393 .ret_type = RET_INTEGER, 394 .arg1_type = ARG_PTR_TO_CTX, 395 .arg2_type = ARG_CONST_MAP_PTR, 396 .arg3_type = ARG_ANYTHING, 397 }; 398 399 static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, 400 struct perf_callchain_entry *trace_in, 401 void *buf, u32 size, u64 flags) 402 { 403 u32 trace_nr, copy_len, elem_size, num_elem, max_depth; 404 bool user_build_id = flags & BPF_F_USER_BUILD_ID; 405 bool crosstask = task && task != current; 406 u32 skip = flags & BPF_F_SKIP_FIELD_MASK; 407 bool user = flags & BPF_F_USER_STACK; 408 struct perf_callchain_entry *trace; 409 bool kernel = !user; 410 int err = -EINVAL; 411 u64 *ips; 412 413 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | 414 BPF_F_USER_BUILD_ID))) 415 goto clear; 416 if (kernel && user_build_id) 417 goto clear; 418 419 elem_size = (user && user_build_id) ? sizeof(struct bpf_stack_build_id) 420 : sizeof(u64); 421 if (unlikely(size % elem_size)) 422 goto clear; 423 424 /* cannot get valid user stack for task without user_mode regs */ 425 if (task && user && !user_mode(regs)) 426 goto err_fault; 427 428 /* get_perf_callchain does not support crosstask user stack walking 429 * but returns an empty stack instead of NULL. 430 */ 431 if (crosstask && user) { 432 err = -EOPNOTSUPP; 433 goto clear; 434 } 435 436 num_elem = size / elem_size; 437 max_depth = num_elem + skip; 438 if (sysctl_perf_event_max_stack < max_depth) 439 max_depth = sysctl_perf_event_max_stack; 440 441 if (trace_in) 442 trace = trace_in; 443 else if (kernel && task) 444 trace = get_callchain_entry_for_task(task, max_depth); 445 else 446 trace = get_perf_callchain(regs, 0, kernel, user, max_depth, 447 crosstask, false); 448 if (unlikely(!trace)) 449 goto err_fault; 450 451 if (trace->nr < skip) 452 goto err_fault; 453 454 trace_nr = trace->nr - skip; 455 trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem; 456 copy_len = trace_nr * elem_size; 457 458 ips = trace->ip + skip; 459 if (user && user_build_id) { 460 struct bpf_stack_build_id *id_offs = buf; 461 u32 i; 462 463 for (i = 0; i < trace_nr; i++) 464 id_offs[i].ip = ips[i]; 465 stack_map_get_build_id_offset(buf, trace_nr, user); 466 } else { 467 memcpy(buf, ips, copy_len); 468 } 469 470 if (size > copy_len) 471 memset(buf + copy_len, 0, size - copy_len); 472 return copy_len; 473 474 err_fault: 475 err = -EFAULT; 476 clear: 477 memset(buf, 0, size); 478 return err; 479 } 480 481 BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size, 482 u64, flags) 483 { 484 return __bpf_get_stack(regs, NULL, NULL, buf, size, flags); 485 } 486 487 const struct bpf_func_proto bpf_get_stack_proto = { 488 .func = bpf_get_stack, 489 .gpl_only = true, 490 .ret_type = RET_INTEGER, 491 .arg1_type = ARG_PTR_TO_CTX, 492 .arg2_type = ARG_PTR_TO_UNINIT_MEM, 493 .arg3_type = ARG_CONST_SIZE_OR_ZERO, 494 .arg4_type = ARG_ANYTHING, 495 }; 496 497 BPF_CALL_4(bpf_get_task_stack, struct task_struct *, task, void *, buf, 498 u32, size, u64, flags) 499 { 500 struct pt_regs *regs; 501 long res = -EINVAL; 502 503 if (!try_get_task_stack(task)) 504 return -EFAULT; 505 506 regs = task_pt_regs(task); 507 if (regs) 508 res = __bpf_get_stack(regs, task, NULL, buf, size, flags); 509 put_task_stack(task); 510 511 return res; 512 } 513 514 const struct bpf_func_proto bpf_get_task_stack_proto = { 515 .func = bpf_get_task_stack, 516 .gpl_only = false, 517 .ret_type = RET_INTEGER, 518 .arg1_type = ARG_PTR_TO_BTF_ID, 519 .arg1_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK], 520 .arg2_type = ARG_PTR_TO_UNINIT_MEM, 521 .arg3_type = ARG_CONST_SIZE_OR_ZERO, 522 .arg4_type = ARG_ANYTHING, 523 }; 524 525 BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx, 526 void *, buf, u32, size, u64, flags) 527 { 528 struct pt_regs *regs = (struct pt_regs *)(ctx->regs); 529 struct perf_event *event = ctx->event; 530 struct perf_callchain_entry *trace; 531 bool kernel, user; 532 int err = -EINVAL; 533 __u64 nr_kernel; 534 535 if (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN)) 536 return __bpf_get_stack(regs, NULL, NULL, buf, size, flags); 537 538 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK | 539 BPF_F_USER_BUILD_ID))) 540 goto clear; 541 542 user = flags & BPF_F_USER_STACK; 543 kernel = !user; 544 545 err = -EFAULT; 546 trace = ctx->data->callchain; 547 if (unlikely(!trace)) 548 goto clear; 549 550 nr_kernel = count_kernel_ip(trace); 551 552 if (kernel) { 553 __u64 nr = trace->nr; 554 555 trace->nr = nr_kernel; 556 err = __bpf_get_stack(regs, NULL, trace, buf, size, flags); 557 558 /* restore nr */ 559 trace->nr = nr; 560 } else { /* user */ 561 u64 skip = flags & BPF_F_SKIP_FIELD_MASK; 562 563 skip += nr_kernel; 564 if (skip > BPF_F_SKIP_FIELD_MASK) 565 goto clear; 566 567 flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip; 568 err = __bpf_get_stack(regs, NULL, trace, buf, size, flags); 569 } 570 return err; 571 572 clear: 573 memset(buf, 0, size); 574 return err; 575 576 } 577 578 const struct bpf_func_proto bpf_get_stack_proto_pe = { 579 .func = bpf_get_stack_pe, 580 .gpl_only = true, 581 .ret_type = RET_INTEGER, 582 .arg1_type = ARG_PTR_TO_CTX, 583 .arg2_type = ARG_PTR_TO_UNINIT_MEM, 584 .arg3_type = ARG_CONST_SIZE_OR_ZERO, 585 .arg4_type = ARG_ANYTHING, 586 }; 587 588 /* Called from eBPF program */ 589 static void *stack_map_lookup_elem(struct bpf_map *map, void *key) 590 { 591 return ERR_PTR(-EOPNOTSUPP); 592 } 593 594 /* Called from syscall */ 595 int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value) 596 { 597 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); 598 struct stack_map_bucket *bucket, *old_bucket; 599 u32 id = *(u32 *)key, trace_len; 600 601 if (unlikely(id >= smap->n_buckets)) 602 return -ENOENT; 603 604 bucket = xchg(&smap->buckets[id], NULL); 605 if (!bucket) 606 return -ENOENT; 607 608 trace_len = bucket->nr * stack_map_data_size(map); 609 memcpy(value, bucket->data, trace_len); 610 memset(value + trace_len, 0, map->value_size - trace_len); 611 612 old_bucket = xchg(&smap->buckets[id], bucket); 613 if (old_bucket) 614 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); 615 return 0; 616 } 617 618 static int stack_map_get_next_key(struct bpf_map *map, void *key, 619 void *next_key) 620 { 621 struct bpf_stack_map *smap = container_of(map, 622 struct bpf_stack_map, map); 623 u32 id; 624 625 WARN_ON_ONCE(!rcu_read_lock_held()); 626 627 if (!key) { 628 id = 0; 629 } else { 630 id = *(u32 *)key; 631 if (id >= smap->n_buckets || !smap->buckets[id]) 632 id = 0; 633 else 634 id++; 635 } 636 637 while (id < smap->n_buckets && !smap->buckets[id]) 638 id++; 639 640 if (id >= smap->n_buckets) 641 return -ENOENT; 642 643 *(u32 *)next_key = id; 644 return 0; 645 } 646 647 static long stack_map_update_elem(struct bpf_map *map, void *key, void *value, 648 u64 map_flags) 649 { 650 return -EINVAL; 651 } 652 653 /* Called from syscall or from eBPF program */ 654 static long stack_map_delete_elem(struct bpf_map *map, void *key) 655 { 656 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); 657 struct stack_map_bucket *old_bucket; 658 u32 id = *(u32 *)key; 659 660 if (unlikely(id >= smap->n_buckets)) 661 return -E2BIG; 662 663 old_bucket = xchg(&smap->buckets[id], NULL); 664 if (old_bucket) { 665 pcpu_freelist_push(&smap->freelist, &old_bucket->fnode); 666 return 0; 667 } else { 668 return -ENOENT; 669 } 670 } 671 672 /* Called when map->refcnt goes to zero, either from workqueue or from syscall */ 673 static void stack_map_free(struct bpf_map *map) 674 { 675 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); 676 677 bpf_map_area_free(smap->elems); 678 pcpu_freelist_destroy(&smap->freelist); 679 bpf_map_area_free(smap); 680 put_callchain_buffers(); 681 } 682 683 static u64 stack_map_mem_usage(const struct bpf_map *map) 684 { 685 struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map); 686 u64 value_size = map->value_size; 687 u64 n_buckets = smap->n_buckets; 688 u64 enties = map->max_entries; 689 u64 usage = sizeof(*smap); 690 691 usage += n_buckets * sizeof(struct stack_map_bucket *); 692 usage += enties * (sizeof(struct stack_map_bucket) + value_size); 693 return usage; 694 } 695 696 BTF_ID_LIST_SINGLE(stack_trace_map_btf_ids, struct, bpf_stack_map) 697 const struct bpf_map_ops stack_trace_map_ops = { 698 .map_meta_equal = bpf_map_meta_equal, 699 .map_alloc = stack_map_alloc, 700 .map_free = stack_map_free, 701 .map_get_next_key = stack_map_get_next_key, 702 .map_lookup_elem = stack_map_lookup_elem, 703 .map_update_elem = stack_map_update_elem, 704 .map_delete_elem = stack_map_delete_elem, 705 .map_check_btf = map_check_no_btf, 706 .map_mem_usage = stack_map_mem_usage, 707 .map_btf_id = &stack_trace_map_btf_ids[0], 708 }; 709