tree: https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git arm-kill-set_fs-5 head: 1086c1cb895540fdf215aecf3ed4a96843d6633e commit: 175180f99fef4558bae0c2fb337150706c4297ea [6/40] ARM: traps: use get_kernel_nofault instead of set_fs() config: arm-defconfig (attached as .config) compiler: arm-linux-gnueabi-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 175180f99fef4558bae0c2fb337150706c4297ea # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): arch/arm/kernel/traps.c:82:6: warning: no previous prototype for 'dump_backtrace_stm' [-Wmissing-prototypes] 82 | void dump_backtrace_stm(u32 *stack, u32 instruction, const char *loglvl) | ^~~~~~~~~~~~~~~~~~ In file included from include/linux/sched/task.h:11, from include/linux/sched/signal.h:9, from include/linux/rcuwait.h:6, from include/linux/percpu-rwsem.h:7, from include/linux/fs.h:33, from include/linux/huge_mm.h:8, from include/linux/mm.h:672, from include/linux/kallsyms.h:12, from arch/arm/kernel/traps.c:14: arch/arm/kernel/traps.c: In function 'dump_mem': 366 | const typeof(val) *__gk_ptr = (ptr); \ | ^ arch/arm/kernel/traps.c:139:9: note: in expansion of macro 'get_kernel_nofault' 139 | if (get_kernel_nofault(val, (u32 *)p)) | ^~~~~~~~~~~~~~~~~~ arch/arm/kernel/traps.c: At top level: arch/arm/kernel/traps.c:430:17: warning: no previous prototype for 'do_undefinstr' [-Wmissing-prototypes] 430 | asmlinkage void do_undefinstr(struct pt_regs *regs) | ^~~~~~~~~~~~~ arch/arm/kernel/traps.c:495:39: warning: no previous prototype for 'handle_fiq_as_nmi' [-Wmissing-prototypes] 495 | asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs) | ^~~~~~~~~~~~~~~~~ arch/arm/kernel/traps.c:514:17: warning: no previous prototype for 'bad_mode' [-Wmissing-prototypes] 514 | asmlinkage void bad_mode(struct pt_regs *regs, int reason) | ^~~~~~~~ arch/arm/kernel/traps.c:587:16: warning: no previous prototype for 'arm_syscall' [-Wmissing-prototypes] 587 | asmlinkage int arm_syscall(int no, struct pt_regs *regs) | ^~~~~~~~~~~ arch/arm/kernel/traps.c:713:1: warning: no previous prototype for 'baddataabort' [-Wmissing-prototypes] 713 | baddataabort(int code, unsigned long instr, struct pt_regs *regs) | ^~~~~~~~~~~~ arch/arm/kernel/traps.c:753:17: warning: no previous prototype for '__div0' [-Wmissing-prototypes] 753 | asmlinkage void __div0(void) | ^~~~~~ arch/arm/kernel/traps.c:760:6: warning: no previous prototype for 'abort' [-Wmissing-prototypes] 760 | void abort(void) | ^~~~~ arch/arm/kernel/traps.c:768:13: warning: no previous prototype for 'trap_init' [-Wmissing-prototypes] 768 | void __init trap_init(void) | ^~~~~~~~~ cc1: some warnings being treated as errors # https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git/commi... git remote add arnd-playground https://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground.git git fetch --no-tags arnd-playground arm-kill-set_fs-5 git checkout 175180f99fef4558bae0c2fb337150706c4297ea vim +366 include/linux/uaccess.h 1a6877b9c0c2ad9 Alexei Starovoitov 2015-08-28 357 0ab32b6f1b88444 Andrew Morton 2015-11-05 358 /** 25f12ae45fc1931 Christoph Hellwig 2020-06-17 359 * get_kernel_nofault(): safely attempt to read from a location 25f12ae45fc1931 Christoph Hellwig 2020-06-17 360 * @val: read into this variable 25f12ae45fc1931 Christoph Hellwig 2020-06-17 361 * @ptr: address to read from 0ab32b6f1b88444 Andrew Morton 2015-11-05 362 * 0ab32b6f1b88444 Andrew Morton 2015-11-05 363 * Returns 0 on success, or -EFAULT. 0ab32b6f1b88444 Andrew Morton 2015-11-05 364 */ 0c389d89abc28ed Linus Torvalds 2020-06-18 365 #define get_kernel_nofault(val, ptr) ({ \ 0c389d89abc28ed Linus Torvalds 2020-06-18 @366 const typeof(val) *__gk_ptr = (ptr); \ 0c389d89abc28ed Linus Torvalds 2020-06-18 367 copy_from_kernel_nofault(&(val), __gk_ptr, sizeof(val));\ 0c389d89abc28ed Linus Torvalds 2020-06-18 368 }) 0ab32b6f1b88444 Andrew Morton 2015-11-05 369 :::::: The code at line 366 was first introduced by commit :::::: 0c389d89abc28edf70ae847ee2fa55acb267b826 maccess: make get_kernel_nofault() check for minimal type compatibility :::::: TO: Linus Torvalds <torvalds(a)linux-foundation.org&gt; :::::: CC: Linus Torvalds <torvalds(a)linux-foundation.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org