From: kernel test robot <lkp@intel.com>
To: Tao Chen <chen.dylane@linux.dev>
Cc: llvm@lists.linux.dev, oe-kbuild-all@lists.linux.dev
Subject: Re: [RFC PATCH bpf-next v2 2/2] bpf: Pass external callchain entry to get_perf_callchain
Date: Fri, 17 Oct 2025 00:31:28 +0800 [thread overview]
Message-ID: <202510170004.yEwSO5VB-lkp@intel.com> (raw)
In-Reply-To: <20251014100128.2721104-3-chen.dylane@linux.dev>
Hi Tao,
[This is a private test report for your RFC patch.]
kernel test robot noticed the following build warnings:
[auto build test WARNING on bpf-next/master]
url: https://github.com/intel-lab-lkp/linux/commits/Tao-Chen/perf-Use-extern-perf_callchain_entry-for-get_perf_callchain/20251014-181245
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link: https://lore.kernel.org/r/20251014100128.2721104-3-chen.dylane%40linux.dev
patch subject: [RFC PATCH bpf-next v2 2/2] bpf: Pass external callchain entry to get_perf_callchain
config: hexagon-allmodconfig (https://download.01.org/0day-ci/archive/20251017/202510170004.yEwSO5VB-lkp@intel.com/config)
compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251017/202510170004.yEwSO5VB-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510170004.yEwSO5VB-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> kernel/bpf/stackmap.c:305:12: warning: stack frame size (1064) exceeds limit (1024) in 'bpf_get_stackid' [-Wframe-larger-than]
305 | BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map,
| ^
>> kernel/bpf/stackmap.c:350:12: warning: stack frame size (1064) exceeds limit (1024) in 'bpf_get_stackid_pe' [-Wframe-larger-than]
350 | BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx,
| ^
>> kernel/bpf/stackmap.c:407:13: warning: stack frame size (1120) exceeds limit (1024) in '__bpf_get_stack' [-Wframe-larger-than]
407 | static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
| ^
3 warnings generated.
vim +/bpf_get_stackid +305 kernel/bpf/stackmap.c
d5a3b1f691865be Alexei Starovoitov 2016-02-17 304
7b04d6d60fcfb5b Song Liu 2020-07-23 @305 BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map,
7b04d6d60fcfb5b Song Liu 2020-07-23 306 u64, flags)
7b04d6d60fcfb5b Song Liu 2020-07-23 307 {
7b04d6d60fcfb5b Song Liu 2020-07-23 308 u32 max_depth = map->value_size / stack_map_data_size(map);
ee2a098851bfbe8 Namhyung Kim 2022-03-14 309 u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
7b04d6d60fcfb5b Song Liu 2020-07-23 310 bool user = flags & BPF_F_USER_STACK;
7b04d6d60fcfb5b Song Liu 2020-07-23 311 struct perf_callchain_entry *trace;
7b04d6d60fcfb5b Song Liu 2020-07-23 312 bool kernel = !user;
8d90c803bbb1151 Tao Chen 2025-10-14 313 struct bpf_perf_callchain_entry entry = { 0 };
7b04d6d60fcfb5b Song Liu 2020-07-23 314
7b04d6d60fcfb5b Song Liu 2020-07-23 315 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
7b04d6d60fcfb5b Song Liu 2020-07-23 316 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
7b04d6d60fcfb5b Song Liu 2020-07-23 317 return -EINVAL;
7b04d6d60fcfb5b Song Liu 2020-07-23 318
ee2a098851bfbe8 Namhyung Kim 2022-03-14 319 max_depth += skip;
ee2a098851bfbe8 Namhyung Kim 2022-03-14 320 if (max_depth > sysctl_perf_event_max_stack)
ee2a098851bfbe8 Namhyung Kim 2022-03-14 321 max_depth = sysctl_perf_event_max_stack;
ee2a098851bfbe8 Namhyung Kim 2022-03-14 322
8d90c803bbb1151 Tao Chen 2025-10-14 323 trace = get_perf_callchain(regs, (struct perf_callchain_entry *)&entry,
8d90c803bbb1151 Tao Chen 2025-10-14 324 kernel, user, max_depth, false, false);
7b04d6d60fcfb5b Song Liu 2020-07-23 325
7b04d6d60fcfb5b Song Liu 2020-07-23 326 return __bpf_get_stackid(map, trace, flags);
7b04d6d60fcfb5b Song Liu 2020-07-23 327 }
7b04d6d60fcfb5b Song Liu 2020-07-23 328
d5a3b1f691865be Alexei Starovoitov 2016-02-17 329 const struct bpf_func_proto bpf_get_stackid_proto = {
d5a3b1f691865be Alexei Starovoitov 2016-02-17 330 .func = bpf_get_stackid,
d5a3b1f691865be Alexei Starovoitov 2016-02-17 331 .gpl_only = true,
d5a3b1f691865be Alexei Starovoitov 2016-02-17 332 .ret_type = RET_INTEGER,
d5a3b1f691865be Alexei Starovoitov 2016-02-17 333 .arg1_type = ARG_PTR_TO_CTX,
d5a3b1f691865be Alexei Starovoitov 2016-02-17 334 .arg2_type = ARG_CONST_MAP_PTR,
d5a3b1f691865be Alexei Starovoitov 2016-02-17 335 .arg3_type = ARG_ANYTHING,
d5a3b1f691865be Alexei Starovoitov 2016-02-17 336 };
d5a3b1f691865be Alexei Starovoitov 2016-02-17 337
7b04d6d60fcfb5b Song Liu 2020-07-23 338 static __u64 count_kernel_ip(struct perf_callchain_entry *trace)
7b04d6d60fcfb5b Song Liu 2020-07-23 339 {
7b04d6d60fcfb5b Song Liu 2020-07-23 340 __u64 nr_kernel = 0;
7b04d6d60fcfb5b Song Liu 2020-07-23 341
7b04d6d60fcfb5b Song Liu 2020-07-23 342 while (nr_kernel < trace->nr) {
7b04d6d60fcfb5b Song Liu 2020-07-23 343 if (trace->ip[nr_kernel] == PERF_CONTEXT_USER)
7b04d6d60fcfb5b Song Liu 2020-07-23 344 break;
7b04d6d60fcfb5b Song Liu 2020-07-23 345 nr_kernel++;
7b04d6d60fcfb5b Song Liu 2020-07-23 346 }
7b04d6d60fcfb5b Song Liu 2020-07-23 347 return nr_kernel;
7b04d6d60fcfb5b Song Liu 2020-07-23 348 }
7b04d6d60fcfb5b Song Liu 2020-07-23 349
7b04d6d60fcfb5b Song Liu 2020-07-23 @350 BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx,
7b04d6d60fcfb5b Song Liu 2020-07-23 351 struct bpf_map *, map, u64, flags)
7b04d6d60fcfb5b Song Liu 2020-07-23 352 {
7b04d6d60fcfb5b Song Liu 2020-07-23 353 struct perf_event *event = ctx->event;
7b04d6d60fcfb5b Song Liu 2020-07-23 354 struct perf_callchain_entry *trace;
7b04d6d60fcfb5b Song Liu 2020-07-23 355 bool kernel, user;
7b04d6d60fcfb5b Song Liu 2020-07-23 356 __u64 nr_kernel;
7b04d6d60fcfb5b Song Liu 2020-07-23 357 int ret;
7b04d6d60fcfb5b Song Liu 2020-07-23 358
7b04d6d60fcfb5b Song Liu 2020-07-23 359 /* perf_sample_data doesn't have callchain, use bpf_get_stackid */
16817ad7e8b3172 Namhyung Kim 2022-09-08 360 if (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN))
7b04d6d60fcfb5b Song Liu 2020-07-23 361 return bpf_get_stackid((unsigned long)(ctx->regs),
7b04d6d60fcfb5b Song Liu 2020-07-23 362 (unsigned long) map, flags, 0, 0);
7b04d6d60fcfb5b Song Liu 2020-07-23 363
7b04d6d60fcfb5b Song Liu 2020-07-23 364 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
7b04d6d60fcfb5b Song Liu 2020-07-23 365 BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
7b04d6d60fcfb5b Song Liu 2020-07-23 366 return -EINVAL;
7b04d6d60fcfb5b Song Liu 2020-07-23 367
7b04d6d60fcfb5b Song Liu 2020-07-23 368 user = flags & BPF_F_USER_STACK;
7b04d6d60fcfb5b Song Liu 2020-07-23 369 kernel = !user;
7b04d6d60fcfb5b Song Liu 2020-07-23 370
7b04d6d60fcfb5b Song Liu 2020-07-23 371 trace = ctx->data->callchain;
7b04d6d60fcfb5b Song Liu 2020-07-23 372 if (unlikely(!trace))
7b04d6d60fcfb5b Song Liu 2020-07-23 373 return -EFAULT;
7b04d6d60fcfb5b Song Liu 2020-07-23 374
7b04d6d60fcfb5b Song Liu 2020-07-23 375 nr_kernel = count_kernel_ip(trace);
7b04d6d60fcfb5b Song Liu 2020-07-23 376
7b04d6d60fcfb5b Song Liu 2020-07-23 377 if (kernel) {
7b04d6d60fcfb5b Song Liu 2020-07-23 378 __u64 nr = trace->nr;
7b04d6d60fcfb5b Song Liu 2020-07-23 379
7b04d6d60fcfb5b Song Liu 2020-07-23 380 trace->nr = nr_kernel;
7b04d6d60fcfb5b Song Liu 2020-07-23 381 ret = __bpf_get_stackid(map, trace, flags);
7b04d6d60fcfb5b Song Liu 2020-07-23 382
7b04d6d60fcfb5b Song Liu 2020-07-23 383 /* restore nr */
7b04d6d60fcfb5b Song Liu 2020-07-23 384 trace->nr = nr;
7b04d6d60fcfb5b Song Liu 2020-07-23 385 } else { /* user */
7b04d6d60fcfb5b Song Liu 2020-07-23 386 u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
7b04d6d60fcfb5b Song Liu 2020-07-23 387
7b04d6d60fcfb5b Song Liu 2020-07-23 388 skip += nr_kernel;
7b04d6d60fcfb5b Song Liu 2020-07-23 389 if (skip > BPF_F_SKIP_FIELD_MASK)
7b04d6d60fcfb5b Song Liu 2020-07-23 390 return -EFAULT;
7b04d6d60fcfb5b Song Liu 2020-07-23 391
7b04d6d60fcfb5b Song Liu 2020-07-23 392 flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
7b04d6d60fcfb5b Song Liu 2020-07-23 393 ret = __bpf_get_stackid(map, trace, flags);
7b04d6d60fcfb5b Song Liu 2020-07-23 394 }
7b04d6d60fcfb5b Song Liu 2020-07-23 395 return ret;
7b04d6d60fcfb5b Song Liu 2020-07-23 396 }
7b04d6d60fcfb5b Song Liu 2020-07-23 397
7b04d6d60fcfb5b Song Liu 2020-07-23 398 const struct bpf_func_proto bpf_get_stackid_proto_pe = {
7b04d6d60fcfb5b Song Liu 2020-07-23 399 .func = bpf_get_stackid_pe,
7b04d6d60fcfb5b Song Liu 2020-07-23 400 .gpl_only = false,
7b04d6d60fcfb5b Song Liu 2020-07-23 401 .ret_type = RET_INTEGER,
7b04d6d60fcfb5b Song Liu 2020-07-23 402 .arg1_type = ARG_PTR_TO_CTX,
7b04d6d60fcfb5b Song Liu 2020-07-23 403 .arg2_type = ARG_CONST_MAP_PTR,
7b04d6d60fcfb5b Song Liu 2020-07-23 404 .arg3_type = ARG_ANYTHING,
7b04d6d60fcfb5b Song Liu 2020-07-23 405 };
7b04d6d60fcfb5b Song Liu 2020-07-23 406
fa28dcb82a38f8e Song Liu 2020-06-29 @407 static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
7b04d6d60fcfb5b Song Liu 2020-07-23 408 struct perf_callchain_entry *trace_in,
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 409 void *buf, u32 size, u64 flags, bool may_fault)
c195651e565ae7f Yonghong Song 2018-04-28 410 {
ee2a098851bfbe8 Namhyung Kim 2022-03-14 411 u32 trace_nr, copy_len, elem_size, num_elem, max_depth;
c195651e565ae7f Yonghong Song 2018-04-28 412 bool user_build_id = flags & BPF_F_USER_BUILD_ID;
b8e3a87a627b575 Jordan Rome 2023-11-08 413 bool crosstask = task && task != current;
c195651e565ae7f Yonghong Song 2018-04-28 414 u32 skip = flags & BPF_F_SKIP_FIELD_MASK;
c195651e565ae7f Yonghong Song 2018-04-28 415 bool user = flags & BPF_F_USER_STACK;
c195651e565ae7f Yonghong Song 2018-04-28 416 struct perf_callchain_entry *trace;
8d90c803bbb1151 Tao Chen 2025-10-14 417 struct bpf_perf_callchain_entry entry = { 0 };
c195651e565ae7f Yonghong Song 2018-04-28 418 bool kernel = !user;
c195651e565ae7f Yonghong Song 2018-04-28 419 int err = -EINVAL;
c195651e565ae7f Yonghong Song 2018-04-28 420 u64 *ips;
c195651e565ae7f Yonghong Song 2018-04-28 421
c195651e565ae7f Yonghong Song 2018-04-28 422 if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
c195651e565ae7f Yonghong Song 2018-04-28 423 BPF_F_USER_BUILD_ID)))
c195651e565ae7f Yonghong Song 2018-04-28 424 goto clear;
c195651e565ae7f Yonghong Song 2018-04-28 425 if (kernel && user_build_id)
c195651e565ae7f Yonghong Song 2018-04-28 426 goto clear;
c195651e565ae7f Yonghong Song 2018-04-28 427
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 428 elem_size = user_build_id ? sizeof(struct bpf_stack_build_id) : sizeof(u64);
c195651e565ae7f Yonghong Song 2018-04-28 429 if (unlikely(size % elem_size))
c195651e565ae7f Yonghong Song 2018-04-28 430 goto clear;
c195651e565ae7f Yonghong Song 2018-04-28 431
fa28dcb82a38f8e Song Liu 2020-06-29 432 /* cannot get valid user stack for task without user_mode regs */
fa28dcb82a38f8e Song Liu 2020-06-29 433 if (task && user && !user_mode(regs))
fa28dcb82a38f8e Song Liu 2020-06-29 434 goto err_fault;
fa28dcb82a38f8e Song Liu 2020-06-29 435
b8e3a87a627b575 Jordan Rome 2023-11-08 436 /* get_perf_callchain does not support crosstask user stack walking
b8e3a87a627b575 Jordan Rome 2023-11-08 437 * but returns an empty stack instead of NULL.
b8e3a87a627b575 Jordan Rome 2023-11-08 438 */
b8e3a87a627b575 Jordan Rome 2023-11-08 439 if (crosstask && user) {
b8e3a87a627b575 Jordan Rome 2023-11-08 440 err = -EOPNOTSUPP;
b8e3a87a627b575 Jordan Rome 2023-11-08 441 goto clear;
b8e3a87a627b575 Jordan Rome 2023-11-08 442 }
b8e3a87a627b575 Jordan Rome 2023-11-08 443
c195651e565ae7f Yonghong Song 2018-04-28 444 num_elem = size / elem_size;
ee2a098851bfbe8 Namhyung Kim 2022-03-14 445 max_depth = num_elem + skip;
ee2a098851bfbe8 Namhyung Kim 2022-03-14 446 if (sysctl_perf_event_max_stack < max_depth)
ee2a098851bfbe8 Namhyung Kim 2022-03-14 447 max_depth = sysctl_perf_event_max_stack;
fa28dcb82a38f8e Song Liu 2020-06-29 448
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 449 if (may_fault)
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 450 rcu_read_lock(); /* need RCU for perf's callchain below */
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 451
7b04d6d60fcfb5b Song Liu 2020-07-23 452 if (trace_in)
7b04d6d60fcfb5b Song Liu 2020-07-23 453 trace = trace_in;
7b04d6d60fcfb5b Song Liu 2020-07-23 454 else if (kernel && task)
ee2a098851bfbe8 Namhyung Kim 2022-03-14 455 trace = get_callchain_entry_for_task(task, max_depth);
fa28dcb82a38f8e Song Liu 2020-06-29 456 else
8d90c803bbb1151 Tao Chen 2025-10-14 457 trace = get_perf_callchain(regs, (struct perf_callchain_entry *)&entry,
8d90c803bbb1151 Tao Chen 2025-10-14 458 kernel, user, max_depth, crosstask, false);
c195651e565ae7f Yonghong Song 2018-04-28 459
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 460 if (unlikely(!trace) || trace->nr < skip) {
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 461 if (may_fault)
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 462 rcu_read_unlock();
c195651e565ae7f Yonghong Song 2018-04-28 463 goto err_fault;
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 464 }
c195651e565ae7f Yonghong Song 2018-04-28 465
ee2a098851bfbe8 Namhyung Kim 2022-03-14 466 trace_nr = trace->nr - skip;
c195651e565ae7f Yonghong Song 2018-04-28 467 trace_nr = (trace_nr <= num_elem) ? trace_nr : num_elem;
c195651e565ae7f Yonghong Song 2018-04-28 468 copy_len = trace_nr * elem_size;
ee2a098851bfbe8 Namhyung Kim 2022-03-14 469
ee2a098851bfbe8 Namhyung Kim 2022-03-14 470 ips = trace->ip + skip;
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 471 if (user_build_id) {
4f4c4fc0153fb11 Andrii Nakryiko 2024-08-29 472 struct bpf_stack_build_id *id_offs = buf;
4f4c4fc0153fb11 Andrii Nakryiko 2024-08-29 473 u32 i;
4f4c4fc0153fb11 Andrii Nakryiko 2024-08-29 474
4f4c4fc0153fb11 Andrii Nakryiko 2024-08-29 475 for (i = 0; i < trace_nr; i++)
4f4c4fc0153fb11 Andrii Nakryiko 2024-08-29 476 id_offs[i].ip = ips[i];
4f4c4fc0153fb11 Andrii Nakryiko 2024-08-29 477 } else {
c195651e565ae7f Yonghong Song 2018-04-28 478 memcpy(buf, ips, copy_len);
4f4c4fc0153fb11 Andrii Nakryiko 2024-08-29 479 }
c195651e565ae7f Yonghong Song 2018-04-28 480
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 481 /* trace/ips should not be dereferenced after this point */
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 482 if (may_fault)
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 483 rcu_read_unlock();
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 484
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 485 if (user_build_id)
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 486 stack_map_get_build_id_offset(buf, trace_nr, user, may_fault);
d4dd9775ec24242 Andrii Nakryiko 2024-08-29 487
c195651e565ae7f Yonghong Song 2018-04-28 488 if (size > copy_len)
c195651e565ae7f Yonghong Song 2018-04-28 489 memset(buf + copy_len, 0, size - copy_len);
c195651e565ae7f Yonghong Song 2018-04-28 490 return copy_len;
c195651e565ae7f Yonghong Song 2018-04-28 491
c195651e565ae7f Yonghong Song 2018-04-28 492 err_fault:
c195651e565ae7f Yonghong Song 2018-04-28 493 err = -EFAULT;
c195651e565ae7f Yonghong Song 2018-04-28 494 clear:
c195651e565ae7f Yonghong Song 2018-04-28 495 memset(buf, 0, size);
c195651e565ae7f Yonghong Song 2018-04-28 496 return err;
c195651e565ae7f Yonghong Song 2018-04-28 497 }
c195651e565ae7f Yonghong Song 2018-04-28 498
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
prev parent reply other threads:[~2025-10-16 16:32 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-14 10:01 [RFC PATCH bpf-next v2 0/2] Pass external callchain entry to get_perf_callchain Tao Chen
2025-10-14 10:01 ` [RFC PATCH bpf-next v2 1/2] perf: Use extern perf_callchain_entry for get_perf_callchain Tao Chen
2025-10-14 10:01 ` [RFC PATCH bpf-next v2 2/2] bpf: Pass external callchain entry to get_perf_callchain Tao Chen
2025-10-14 12:14 ` Jiri Olsa
2025-10-14 12:34 ` Tao Chen
2025-10-14 15:02 ` Alexei Starovoitov
2025-10-16 20:39 ` Andrii Nakryiko
2025-10-18 7:51 ` Tao Chen
2025-10-21 16:37 ` Andrii Nakryiko
2025-10-23 6:11 ` Tao Chen
2025-10-16 11:59 ` kernel test robot
2025-10-16 16:31 ` kernel test robot [this message]
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