tree: git://git.infradead.org/users/hch/misc.git maccess-fixups.3 head: ffc491b4d7cbc956087e89dbd171863c411f3868 commit: 5de7b23a3f5410a896ab792fd3e580d5f0e54258 [15/18] x86: use non-set_fs based maccess routines config: x86_64-randconfig-a001-20200513 (attached as .config) compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0 reproduce: git checkout 5de7b23a3f5410a896ab792fd3e580d5f0e54258 # save the attached .config to linux build tree make ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): ld: kernel/trace/bpf_trace.o: in function `bpf_probe_read_kernel_str_common': kernel/trace/bpf_trace.c:252: undefined reference to `strncpy_from_kernel_nofault' ld: kernel/trace/bpf_trace.c:252: undefined reference to `strncpy_from_kernel_nofault' ld: kernel/trace/bpf_trace.o: in function `bpf_strncpy': kernel/trace/bpf_trace.c:344: undefined reference to `strncpy_from_kernel_nofault' ld: kernel/trace/trace_kprobe.o: in function `fetch_store_string': vim +1250 kernel/trace/trace_kprobe.c 88903c464321cd Masami Hiramatsu 2019-05-15 1229 533059281ee594 Masami Hiramatsu 2018-04-25 1230 /* 533059281ee594 Masami Hiramatsu 2018-04-25 1231 * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max 533059281ee594 Masami Hiramatsu 2018-04-25 1232 * length and relative data location. 533059281ee594 Masami Hiramatsu 2018-04-25 1233 */ 9178412ddf5a98 Masami Hiramatsu 2018-04-25 1234 static nokprobe_inline int 9178412ddf5a98 Masami Hiramatsu 2018-04-25 1235 fetch_store_string(unsigned long addr, void *dest, void *base) 533059281ee594 Masami Hiramatsu 2018-04-25 1236 { 9178412ddf5a98 Masami Hiramatsu 2018-04-25 1237 int maxlen = get_loc_len(*(u32 *)dest); 88903c464321cd Masami Hiramatsu 2019-05-15 1238 void *__dest; 533059281ee594 Masami Hiramatsu 2018-04-25 1239 long ret; 533059281ee594 Masami Hiramatsu 2018-04-25 1240 9178412ddf5a98 Masami Hiramatsu 2018-04-25 1241 if (unlikely(!maxlen)) 9178412ddf5a98 Masami Hiramatsu 2018-04-25 1242 return -ENOMEM; 88903c464321cd Masami Hiramatsu 2019-05-15 1243 88903c464321cd Masami Hiramatsu 2019-05-15 1244 __dest = get_loc_data(dest, base); 88903c464321cd Masami Hiramatsu 2019-05-15 1245 533059281ee594 Masami Hiramatsu 2018-04-25 1246 /* 533059281ee594 Masami Hiramatsu 2018-04-25 1247 * Try to get string again, since the string can be changed while 533059281ee594 Masami Hiramatsu 2018-04-25 1248 * probing. 533059281ee594 Masami Hiramatsu 2018-04-25 1249 */ 334a11cc65f45f Christoph Hellwig 2020-05-13 @1250 ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen); 334a11cc65f45f Christoph Hellwig 2020-05-13 1251 if (ret < 0) 334a11cc65f45f Christoph Hellwig 2020-05-13 1252 ret = strncpy_from_user_nofault(__dest, (void __user *)addr, 334a11cc65f45f Christoph Hellwig 2020-05-13 1253 maxlen); 88903c464321cd Masami Hiramatsu 2019-05-15 1254 if (ret >= 0) 88903c464321cd Masami Hiramatsu 2019-05-15 1255 *(u32 *)dest = make_data_loc(ret, __dest - base); 88903c464321cd Masami Hiramatsu 2019-05-15 1256 88903c464321cd Masami Hiramatsu 2019-05-15 1257 return ret; 88903c464321cd Masami Hiramatsu 2019-05-15 1258 } 88903c464321cd Masami Hiramatsu 2019-05-15 1259 :::::: The code at line 1250 was first introduced by commit :::::: 334a11cc65f45f12f7fb8929928e68f7fb63d26d maccess: remove strncpy_from_unsafe :::::: TO: Christoph Hellwig <hch(a)lst.de&gt; :::::: CC: Christoph Hellwig <hch(a)lst.de&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org