[kbuild-all] [linux-next:master 7274/8137] kernel/trace/bpf_trace.c:538:2: warning: function '____bpf_trace_printk' might be a candidate for 'gnu_printf' format attribute

tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: ca0e494af5edb59002665bf12871e94b4163a257 commit: ac5a72ea5c8989871e61f6bb0852e0f91de51ebe [7274/8137] bpf: Use dedicated bpf_trace_printk event instead of trace_printk() config: mips-randconfig-r022-20200715 (attached as .config) compiler: mips64-linux-gcc (GCC) 9.3.0 reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross git checkout ac5a72ea5c8989871e61f6bb0852e0f91de51ebe # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=mips If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): kernel/trace/bpf_trace.c: In function '____bpf_trace_printk': 538 | return __BPF_TP_EMIT(); | ^~~~~~ kernel/trace/bpf_trace.c:538:2: warning: function '____bpf_trace_printk' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format] kernel/trace/bpf_trace.c:538:2: warning: function '____bpf_trace_printk' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format] kernel/trace/bpf_trace.c:538:2: warning: function '____bpf_trace_printk' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format] kernel/trace/bpf_trace.c:538:2: warning: function '____bpf_trace_printk' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format] kernel/trace/bpf_trace.c:538:2: warning: function '____bpf_trace_printk' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format] kernel/trace/bpf_trace.c:538:2: warning: function '____bpf_trace_printk' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format] kernel/trace/bpf_trace.c:538:2: warning: function '____bpf_trace_printk' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format] vim +538 kernel/trace/bpf_trace.c ac5a72ea5c8989 Alan Maguire 2020-07-13 405 9c959c863f8217 Alexei Starovoitov 2015-03-25 406 /* 7bda4b40c5624c John Fastabend 2017-07-02 407 * Only limited trace_printk() conversion specifiers allowed: 2df6bb5493f83c Song Liu 2020-06-29 408 * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %pB %pks %pus %s 9c959c863f8217 Alexei Starovoitov 2015-03-25 409 */ f3694e00123802 Daniel Borkmann 2016-09-09 410 BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, f3694e00123802 Daniel Borkmann 2016-09-09 411 u64, arg2, u64, arg3) 9c959c863f8217 Alexei Starovoitov 2015-03-25 412 { b2a5212fb63456 Daniel Borkmann 2020-05-15 413 int i, mod[3] = {}, fmt_cnt = 0; b2a5212fb63456 Daniel Borkmann 2020-05-15 414 char buf[64], fmt_ptype; b2a5212fb63456 Daniel Borkmann 2020-05-15 415 void *unsafe_ptr = NULL; 8d3b7dce862291 Alexei Starovoitov 2015-08-28 416 bool str_seen = false; 9c959c863f8217 Alexei Starovoitov 2015-03-25 417 9c959c863f8217 Alexei Starovoitov 2015-03-25 418 /* 9c959c863f8217 Alexei Starovoitov 2015-03-25 419 * bpf_check()->check_func_arg()->check_stack_boundary() 9c959c863f8217 Alexei Starovoitov 2015-03-25 420 * guarantees that fmt points to bpf program stack, 9c959c863f8217 Alexei Starovoitov 2015-03-25 421 * fmt_size bytes of it were initialized and fmt_size > 0 9c959c863f8217 Alexei Starovoitov 2015-03-25 422 */ 9c959c863f8217 Alexei Starovoitov 2015-03-25 423 if (fmt[--fmt_size] != 0) 9c959c863f8217 Alexei Starovoitov 2015-03-25 424 return -EINVAL; 9c959c863f8217 Alexei Starovoitov 2015-03-25 425 9c959c863f8217 Alexei Starovoitov 2015-03-25 426 /* check format string for allowed specifiers */ 9c959c863f8217 Alexei Starovoitov 2015-03-25 427 for (i = 0; i < fmt_size; i++) { 9c959c863f8217 Alexei Starovoitov 2015-03-25 428 if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i])) 9c959c863f8217 Alexei Starovoitov 2015-03-25 429 return -EINVAL; 9c959c863f8217 Alexei Starovoitov 2015-03-25 430 9c959c863f8217 Alexei Starovoitov 2015-03-25 431 if (fmt[i] != '%') 9c959c863f8217 Alexei Starovoitov 2015-03-25 432 continue; 9c959c863f8217 Alexei Starovoitov 2015-03-25 433 9c959c863f8217 Alexei Starovoitov 2015-03-25 434 if (fmt_cnt >= 3) 9c959c863f8217 Alexei Starovoitov 2015-03-25 435 return -EINVAL; 9c959c863f8217 Alexei Starovoitov 2015-03-25 436 9c959c863f8217 Alexei Starovoitov 2015-03-25 437 /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */ 9c959c863f8217 Alexei Starovoitov 2015-03-25 438 i++; 9c959c863f8217 Alexei Starovoitov 2015-03-25 439 if (fmt[i] == 'l') { 9c959c863f8217 Alexei Starovoitov 2015-03-25 440 mod[fmt_cnt]++; 9c959c863f8217 Alexei Starovoitov 2015-03-25 441 i++; b2a5212fb63456 Daniel Borkmann 2020-05-15 442 } else if (fmt[i] == 'p') { 9c959c863f8217 Alexei Starovoitov 2015-03-25 443 mod[fmt_cnt]++; b2a5212fb63456 Daniel Borkmann 2020-05-15 444 if ((fmt[i + 1] == 'k' || b2a5212fb63456 Daniel Borkmann 2020-05-15 445 fmt[i + 1] == 'u') && b2a5212fb63456 Daniel Borkmann 2020-05-15 446 fmt[i + 2] == 's') { b2a5212fb63456 Daniel Borkmann 2020-05-15 447 fmt_ptype = fmt[i + 1]; b2a5212fb63456 Daniel Borkmann 2020-05-15 448 i += 2; b2a5212fb63456 Daniel Borkmann 2020-05-15 449 goto fmt_str; b2a5212fb63456 Daniel Borkmann 2020-05-15 450 } b2a5212fb63456 Daniel Borkmann 2020-05-15 451 2df6bb5493f83c Song Liu 2020-06-29 452 if (fmt[i + 1] == 'B') { 2df6bb5493f83c Song Liu 2020-06-29 453 i++; 2df6bb5493f83c Song Liu 2020-06-29 454 goto fmt_next; 2df6bb5493f83c Song Liu 2020-06-29 455 } 2df6bb5493f83c Song Liu 2020-06-29 456 1efb6ee3edea57 Martynas Pumputis 2018-11-23 457 /* disallow any further format extensions */ 1efb6ee3edea57 Martynas Pumputis 2018-11-23 458 if (fmt[i + 1] != 0 && 1efb6ee3edea57 Martynas Pumputis 2018-11-23 459 !isspace(fmt[i + 1]) && 1efb6ee3edea57 Martynas Pumputis 2018-11-23 460 !ispunct(fmt[i + 1])) 9c959c863f8217 Alexei Starovoitov 2015-03-25 461 return -EINVAL; b2a5212fb63456 Daniel Borkmann 2020-05-15 462 b2a5212fb63456 Daniel Borkmann 2020-05-15 463 goto fmt_next; b2a5212fb63456 Daniel Borkmann 2020-05-15 464 } else if (fmt[i] == 's') { b2a5212fb63456 Daniel Borkmann 2020-05-15 465 mod[fmt_cnt]++; b2a5212fb63456 Daniel Borkmann 2020-05-15 466 fmt_ptype = fmt[i]; b2a5212fb63456 Daniel Borkmann 2020-05-15 467 fmt_str: 8d3b7dce862291 Alexei Starovoitov 2015-08-28 468 if (str_seen) 8d3b7dce862291 Alexei Starovoitov 2015-08-28 469 /* allow only one '%s' per fmt string */ 8d3b7dce862291 Alexei Starovoitov 2015-08-28 470 return -EINVAL; 8d3b7dce862291 Alexei Starovoitov 2015-08-28 471 str_seen = true; 8d3b7dce862291 Alexei Starovoitov 2015-08-28 472 b2a5212fb63456 Daniel Borkmann 2020-05-15 473 if (fmt[i + 1] != 0 && b2a5212fb63456 Daniel Borkmann 2020-05-15 474 !isspace(fmt[i + 1]) && b2a5212fb63456 Daniel Borkmann 2020-05-15 475 !ispunct(fmt[i + 1])) b2a5212fb63456 Daniel Borkmann 2020-05-15 476 return -EINVAL; b2a5212fb63456 Daniel Borkmann 2020-05-15 477 8d3b7dce862291 Alexei Starovoitov 2015-08-28 478 switch (fmt_cnt) { b2a5212fb63456 Daniel Borkmann 2020-05-15 479 case 0: b2a5212fb63456 Daniel Borkmann 2020-05-15 480 unsafe_ptr = (void *)(long)arg1; f3694e00123802 Daniel Borkmann 2016-09-09 481 arg1 = (long)buf; 8d3b7dce862291 Alexei Starovoitov 2015-08-28 482 break; b2a5212fb63456 Daniel Borkmann 2020-05-15 483 case 1: b2a5212fb63456 Daniel Borkmann 2020-05-15 484 unsafe_ptr = (void *)(long)arg2; f3694e00123802 Daniel Borkmann 2016-09-09 485 arg2 = (long)buf; 8d3b7dce862291 Alexei Starovoitov 2015-08-28 486 break; b2a5212fb63456 Daniel Borkmann 2020-05-15 487 case 2: b2a5212fb63456 Daniel Borkmann 2020-05-15 488 unsafe_ptr = (void *)(long)arg3; f3694e00123802 Daniel Borkmann 2016-09-09 489 arg3 = (long)buf; 8d3b7dce862291 Alexei Starovoitov 2015-08-28 490 break; 8d3b7dce862291 Alexei Starovoitov 2015-08-28 491 } b2a5212fb63456 Daniel Borkmann 2020-05-15 492 d7b2977b816223 Christoph Hellwig 2020-06-08 493 bpf_trace_copy_string(buf, unsafe_ptr, fmt_ptype, 8d3b7dce862291 Alexei Starovoitov 2015-08-28 494 sizeof(buf)); b2a5212fb63456 Daniel Borkmann 2020-05-15 495 goto fmt_next; 9c959c863f8217 Alexei Starovoitov 2015-03-25 496 } 9c959c863f8217 Alexei Starovoitov 2015-03-25 497 9c959c863f8217 Alexei Starovoitov 2015-03-25 498 if (fmt[i] == 'l') { 9c959c863f8217 Alexei Starovoitov 2015-03-25 499 mod[fmt_cnt]++; 9c959c863f8217 Alexei Starovoitov 2015-03-25 500 i++; 9c959c863f8217 Alexei Starovoitov 2015-03-25 501 } 9c959c863f8217 Alexei Starovoitov 2015-03-25 502 7bda4b40c5624c John Fastabend 2017-07-02 503 if (fmt[i] != 'i' && fmt[i] != 'd' && 7bda4b40c5624c John Fastabend 2017-07-02 504 fmt[i] != 'u' && fmt[i] != 'x') 9c959c863f8217 Alexei Starovoitov 2015-03-25 505 return -EINVAL; b2a5212fb63456 Daniel Borkmann 2020-05-15 506 fmt_next: 9c959c863f8217 Alexei Starovoitov 2015-03-25 507 fmt_cnt++; 9c959c863f8217 Alexei Starovoitov 2015-03-25 508 } 9c959c863f8217 Alexei Starovoitov 2015-03-25 509 88a5c690b66110 Daniel Borkmann 2017-08-16 510 /* Horrid workaround for getting va_list handling working with different 88a5c690b66110 Daniel Borkmann 2017-08-16 511 * argument type combinations generically for 32 and 64 bit archs. 88a5c690b66110 Daniel Borkmann 2017-08-16 512 */ 88a5c690b66110 Daniel Borkmann 2017-08-16 513 #define __BPF_TP_EMIT() __BPF_ARG3_TP() 88a5c690b66110 Daniel Borkmann 2017-08-16 514 #define __BPF_TP(...) \ ac5a72ea5c8989 Alan Maguire 2020-07-13 515 bpf_do_trace_printk(fmt, ##__VA_ARGS__) 88a5c690b66110 Daniel Borkmann 2017-08-16 516 88a5c690b66110 Daniel Borkmann 2017-08-16 517 #define __BPF_ARG1_TP(...) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 518 ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64)) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 519 ? __BPF_TP(arg1, ##__VA_ARGS__) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 520 : ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32)) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 521 ? __BPF_TP((long)arg1, ##__VA_ARGS__) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 522 : __BPF_TP((u32)arg1, ##__VA_ARGS__))) 88a5c690b66110 Daniel Borkmann 2017-08-16 523 88a5c690b66110 Daniel Borkmann 2017-08-16 524 #define __BPF_ARG2_TP(...) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 525 ((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64)) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 526 ? __BPF_ARG1_TP(arg2, ##__VA_ARGS__) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 527 : ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32)) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 528 ? __BPF_ARG1_TP((long)arg2, ##__VA_ARGS__) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 529 : __BPF_ARG1_TP((u32)arg2, ##__VA_ARGS__))) 88a5c690b66110 Daniel Borkmann 2017-08-16 530 88a5c690b66110 Daniel Borkmann 2017-08-16 531 #define __BPF_ARG3_TP(...) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 532 ((mod[2] == 2 || (mod[2] == 1 && __BITS_PER_LONG == 64)) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 533 ? __BPF_ARG2_TP(arg3, ##__VA_ARGS__) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 534 : ((mod[2] == 1 || (mod[2] == 0 && __BITS_PER_LONG == 32)) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 535 ? __BPF_ARG2_TP((long)arg3, ##__VA_ARGS__) \ 88a5c690b66110 Daniel Borkmann 2017-08-16 536 : __BPF_ARG2_TP((u32)arg3, ##__VA_ARGS__))) 88a5c690b66110 Daniel Borkmann 2017-08-16 537 88a5c690b66110 Daniel Borkmann 2017-08-16 @538 return __BPF_TP_EMIT(); 9c959c863f8217 Alexei Starovoitov 2015-03-25 539 } 9c959c863f8217 Alexei Starovoitov 2015-03-25 540 :::::: The code at line 538 was first introduced by commit :::::: 88a5c690b66110ad255380d8f629c629cf6ca559 bpf: fix bpf_trace_printk on 32 bit archs :::::: TO: Daniel Borkmann <daniel(a)iogearbox.net&gt; :::::: CC: David S. Miller <davem(a)davemloft.net&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org