Hi Masami, [FYI, it's a private test report for your RFC patch.] [auto build test WARNING on rostedt-trace/for-next] [also build test WARNING on bpf-next/master bpf/master linus/master v5.16 next-20220112] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Masami-Hiramatsu/fprobe-Add-ftra... base: https://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git for-next config: i386-allyesconfig (https://download.01.org/0day-ci/archive/20220113/202201130629.IyZ9vaDV-lk...) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce (this is a W=1 build): # https://github.com/0day-ci/linux/commit/c0e0471b58c3c9122bbff7523f97a3635... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Masami-Hiramatsu/fprobe-Add-ftrace-based-probe-APIs/20220112-000050 git checkout c0e0471b58c3c9122bbff7523f97a363558284eb # save the config file to linux build tree mkdir build_dir make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash arch/x86/kernel/ 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 >>): 14 | __used __visible void arch_rethook_trampoline_callback(struct pt_regs *regs) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ vim +/arch_rethook_trampoline_callback +14 arch/x86/kernel/rethook.c 3727c0ee2be25c Masami Hiramatsu 2022-01-12 10 3727c0ee2be25c Masami Hiramatsu 2022-01-12 11 /* 3727c0ee2be25c Masami Hiramatsu 2022-01-12 12 * Called from arch_rethook_trampoline 3727c0ee2be25c Masami Hiramatsu 2022-01-12 13 */ 3727c0ee2be25c Masami Hiramatsu 2022-01-12 @14 __used __visible void arch_rethook_trampoline_callback(struct pt_regs *regs) 3727c0ee2be25c Masami Hiramatsu 2022-01-12 15 { 3727c0ee2be25c Masami Hiramatsu 2022-01-12 16 unsigned long *frame_pointer; 3727c0ee2be25c Masami Hiramatsu 2022-01-12 17 3727c0ee2be25c Masami Hiramatsu 2022-01-12 18 /* fixup registers */ 3727c0ee2be25c Masami Hiramatsu 2022-01-12 19 regs->cs = __KERNEL_CS; 3727c0ee2be25c Masami Hiramatsu 2022-01-12 20 #ifdef CONFIG_X86_32 3727c0ee2be25c Masami Hiramatsu 2022-01-12 21 regs->gs = 0; 3727c0ee2be25c Masami Hiramatsu 2022-01-12 22 #endif 3727c0ee2be25c Masami Hiramatsu 2022-01-12 23 regs->ip = (unsigned long)&arch_rethook_trampoline; 3727c0ee2be25c Masami Hiramatsu 2022-01-12 24 regs->orig_ax = ~0UL; 3727c0ee2be25c Masami Hiramatsu 2022-01-12 25 regs->sp += sizeof(long); 3727c0ee2be25c Masami Hiramatsu 2022-01-12 26 frame_pointer = &regs->sp + 1; 3727c0ee2be25c Masami Hiramatsu 2022-01-12 27 3727c0ee2be25c Masami Hiramatsu 2022-01-12 28 /* 3727c0ee2be25c Masami Hiramatsu 2022-01-12 29 * The return address at 'frame_pointer' is recovered by the 3727c0ee2be25c Masami Hiramatsu 2022-01-12 30 * arch_rethook_fixup_return() which called from this 3727c0ee2be25c Masami Hiramatsu 2022-01-12 31 * rethook_trampoline_handler(). 3727c0ee2be25c Masami Hiramatsu 2022-01-12 32 */ 3727c0ee2be25c Masami Hiramatsu 2022-01-12 33 rethook_trampoline_handler(regs, (unsigned long)frame_pointer); 3727c0ee2be25c Masami Hiramatsu 2022-01-12 34 3727c0ee2be25c Masami Hiramatsu 2022-01-12 35 /* 3727c0ee2be25c Masami Hiramatsu 2022-01-12 36 * Copy FLAGS to 'pt_regs::sp' so that arch_rethook_trapmoline() 3727c0ee2be25c Masami Hiramatsu 2022-01-12 37 * can do RET right after POPF. 3727c0ee2be25c Masami Hiramatsu 2022-01-12 38 */ 3727c0ee2be25c Masami Hiramatsu 2022-01-12 39 regs->sp = regs->flags; 3727c0ee2be25c Masami Hiramatsu 2022-01-12 40 } 3727c0ee2be25c Masami Hiramatsu 2022-01-12 41 NOKPROBE_SYMBOL(arch_rethook_trampoline_callback); 3727c0ee2be25c Masami Hiramatsu 2022-01-12 42 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org