Hi Andrii, I love your patch! Yet something to improve: [auto build test ERROR on bpf-next/master] url: https://github.com/intel-lab-lkp/linux/commits/Andrii-Nakryiko/bpf-split-off-basic-BPF-verifier-log-into-separate-file/20230317-023431 base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master patch link: https://lore.kernel.org/r/20230316183013.2882810-4-andrii%40kernel.org patch subject: [PATCH bpf-next 3/6] bpf: switch BPF verifier log to be a rotating log by default config: i386-randconfig-a002-20230313 (https://download.01.org/0day-ci/archive/20230317/202303171242.biyrTbVN-lkp@xxxxxxxxx/config) compiler: gcc-11 (Debian 11.3.0-8) 11.3.0 reproduce (this is a W=1 build): # https://github.com/intel-lab-lkp/linux/commit/f2876fe2427e5bdfbbb27980025b969c93f46c4b git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review Andrii-Nakryiko/bpf-split-off-basic-BPF-verifier-log-into-separate-file/20230317-023431 git checkout f2876fe2427e5bdfbbb27980025b969c93f46c4b # save the config file mkdir build_dir && cp config build_dir/.config make W=1 O=build_dir ARCH=i386 olddefconfig make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash If you fix the issue, kindly add following tag where applicable | Reported-by: kernel test robot <lkp@xxxxxxxxx> | Link: https://lore.kernel.org/oe-kbuild-all/202303171242.biyrTbVN-lkp@xxxxxxxxx/ All errors (new ones prefixed by >>): ld: kernel/bpf/log.o: in function `bpf_verifier_vlog': >> kernel/bpf/log.c:59: undefined reference to `__umoddi3' >> ld: kernel/bpf/log.c:60: undefined reference to `__umoddi3' ld: kernel/bpf/log.o: in function `bpf_vlog_finalize': kernel/bpf/log.c:212: undefined reference to `__umoddi3' vim +59 kernel/bpf/log.c 17 18 void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt, 19 va_list args) 20 { 21 unsigned int n; 22 23 n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args); 24 25 WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1, 26 "verifier log line truncated - local buffer too short\n"); 27 28 if (log->level == BPF_LOG_KERNEL) { 29 bool newline = n > 0 && log->kbuf[n - 1] == '\n'; 30 31 pr_err("BPF: %s%s", log->kbuf, newline ? "" : "\n"); 32 return; 33 } 34 35 if (log->level & BPF_LOG_FIXED) { 36 n = min(log->len_total - bpf_log_used(log) - 1, n); 37 log->kbuf[n] = '\0'; 38 n += 1; 39 40 if (copy_to_user(log->ubuf + log->end_pos, log->kbuf, n)) 41 goto fail; 42 43 log->end_pos += n - 1; /* don't count terminating '\0' */ 44 } else { 45 u64 new_end, new_start, cur_pos; 46 u32 buf_start, buf_end, new_n; 47 48 log->kbuf[n] = '\0'; 49 n += 1; 50 51 new_end = log->end_pos + n; 52 if (new_end - log->start_pos >= log->len_total) 53 new_start = new_end - log->len_total; 54 else 55 new_start = log->start_pos; 56 new_n = min(n, log->len_total); 57 cur_pos = new_end - new_n; 58 > 59 buf_start = cur_pos % log->len_total; > 60 buf_end = new_end % log->len_total; 61 /* new_end and buf_end are exclusive indices, so if buf_end is 62 * exactly zero, then it actually points right to the end of 63 * ubuf and there is no wrap around 64 */ 65 if (buf_end == 0) 66 buf_end = log->len_total; 67 68 /* if buf_start > buf_end, we wrapped around; 69 * if buf_start == buf_end, then we fill ubuf completely; we 70 * can't have buf_start == buf_end to mean that there is 71 * nothing to write, because we always write at least 72 * something, even if terminal '\0' 73 */ 74 if (buf_start < buf_end) { 75 /* message fits within contiguous chunk of ubuf */ 76 if (copy_to_user(log->ubuf + buf_start, 77 log->kbuf + n - new_n, 78 buf_end - buf_start)) 79 goto fail; 80 } else { 81 /* message wraps around the end of ubuf, copy in two chunks */ 82 if (copy_to_user(log->ubuf + buf_start, 83 log->kbuf + n - new_n, 84 log->len_total - buf_start)) 85 goto fail; 86 if (copy_to_user(log->ubuf, 87 log->kbuf + n - buf_end, 88 buf_end)) 89 goto fail; 90 } 91 92 log->start_pos = new_start; 93 log->end_pos = new_end - 1; /* don't count terminating '\0' */ 94 } 95 96 return; 97 fail: 98 log->ubuf = NULL; 99 } 100 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests
