Hi Steven, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: f8e6dfc64f6135d1b6c5215c14cd30b9b60a0008 commit: d19ad0775dcd64b49eecf4fa79c17959ebfbd26b ftrace: Have the callbacks receive a struct ftrace_regs instead of pt_regs date: 9 months ago config: nds32-randconfig-r001-20210813 (attached as .config) compiler: nds32le-linux-gcc (GCC) 10.3.0 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 # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit... git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout d19ad0775dcd64b49eecf4fa79c17959ebfbd26b # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.3.0 make.cross ARCH=nds32 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 >>): arch/nds32/kernel/ftrace.c: In function '_mcount': arch/nds32/kernel/ftrace.c:24:28: warning: comparison of distinct pointer types lacks a cast 24 | if (ftrace_trace_function != ftrace_stub) | ^~ 29 | if (ftrace_graph_return != (trace_func_graph_ret_t)ftrace_stub | ^ arch/nds32/kernel/ftrace.c: At top level: arch/nds32/kernel/ftrace.c:198:6: warning: no previous prototype for 'prepare_ftrace_return' [-Wmissing-prototypes] 198 | void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, | ^~~~~~~~~~~~~~~~~~~~~ vim +29 arch/nds32/kernel/ftrace.c a18082575c6648 Zong Li 2018-08-15 17 a18082575c6648 Zong Li 2018-08-15 18 noinline void _mcount(unsigned long parent_ip) a18082575c6648 Zong Li 2018-08-15 19 { a18082575c6648 Zong Li 2018-08-15 20 /* save all state by the compiler prologue */ a18082575c6648 Zong Li 2018-08-15 21 a18082575c6648 Zong Li 2018-08-15 22 unsigned long ip = (unsigned long)__builtin_return_address(0); a18082575c6648 Zong Li 2018-08-15 23 a18082575c6648 Zong Li 2018-08-15 @24 if (ftrace_trace_function != ftrace_stub) a18082575c6648 Zong Li 2018-08-15 25 ftrace_trace_function(ip - MCOUNT_INSN_SIZE, parent_ip, a18082575c6648 Zong Li 2018-08-15 26 NULL, NULL); a18082575c6648 Zong Li 2018-08-15 27 1e9b14c0d92b61 Zong Li 2018-08-15 28 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 1e9b14c0d92b61 Zong Li 2018-08-15 @29 if (ftrace_graph_return != (trace_func_graph_ret_t)ftrace_stub 1e9b14c0d92b61 Zong Li 2018-08-15 30 || ftrace_graph_entry != ftrace_graph_entry_stub) 1e9b14c0d92b61 Zong Li 2018-08-15 31 ftrace_graph_caller(); 1e9b14c0d92b61 Zong Li 2018-08-15 32 #endif 1e9b14c0d92b61 Zong Li 2018-08-15 33 a18082575c6648 Zong Li 2018-08-15 34 /* restore all state by the compiler epilogue */ a18082575c6648 Zong Li 2018-08-15 35 } a18082575c6648 Zong Li 2018-08-15 36 EXPORT_SYMBOL(_mcount); 1e9b14c0d92b61 Zong Li 2018-08-15 37 :::::: The code at line 29 was first introduced by commit :::::: 1e9b14c0d92b61a0979fd5ee24d5e7f080f11030 nds32/ftrace: Support static function graph tracer :::::: TO: Zong Li <zong(a)andestech.com&gt; :::::: CC: Greentime Hu <greentime(a)andestech.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org