tree: https://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git kprobes/kretprobe-stackfix-v9 head: 7a69e2b70adeabbf3e3c1be8a18b43188c4d085d commit: e4d6ef1b03f84257031acd58c208dd0ffa92548c [14/22] x86/kprobes: Add UNWIND_HINT_FUNC on kretprobe_trampoline() config: i386-randconfig-a002-20210712 (attached as .config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce (this is a W=1 build): # https://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git/commit... git remote add mhiramat https://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git git fetch --no-tags mhiramat kprobes/kretprobe-stackfix-v9 git checkout e4d6ef1b03f84257031acd58c208dd0ffa92548c # save the attached .config to linux build tree mkdir build_dir make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash arch/x86/kernel/kprobes/ 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 >>): 1061 | STACK_FRAME_NON_STANDARD_FP(__kretprobe_trampoline); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/x86/kernel/kprobes/core.c:1061:1: error: type defaults to 'int' in declaration of 'STACK_FRAME_NON_STANDARD_FP' [-Werror=implicit-int] arch/x86/kernel/kprobes/core.c:1066:24: warning: no previous prototype for 'trampoline_handler' [-Wmissing-prototypes] 1066 | __used __visible void *trampoline_handler(struct pt_regs *regs) | ^~~~~~~~~~~~~~~~~~ cc1: some warnings being treated as errors vim +1061 arch/x86/kernel/kprobes/core.c 1015 1016 /* 1017 * When a retprobed function returns, this code saves registers and 1018 * calls trampoline_handler() runs, which calls the kretprobe's handler. 1019 */ 1020 asm( 1021 ".text\n" 1022 ".global __kretprobe_trampoline\n" 1023 ".type __kretprobe_trampoline, @function\n" 1024 "__kretprobe_trampoline:\n" 1025 /* We don't bother saving the ss register */ 1026 #ifdef CONFIG_X86_64 1027 " pushq %rsp\n" 1028 UNWIND_HINT_FUNC 1029 " pushfq\n" 1030 SAVE_REGS_STRING 1031 " movq %rsp, %rdi\n" 1032 " call trampoline_handler\n" 1033 /* Replace saved sp with true return address. */ 1034 " movq %rax, 19*8(%rsp)\n" 1035 RESTORE_REGS_STRING 1036 " popfq\n" 1037 #else 1038 " pushl %esp\n" 1039 UNWIND_HINT_FUNC 1040 " pushfl\n" 1041 SAVE_REGS_STRING 1042 " movl %esp, %eax\n" 1043 " call trampoline_handler\n" 1044 /* Replace saved sp with true return address. */ 1045 " movl %eax, 15*4(%esp)\n" 1046 RESTORE_REGS_STRING 1047 " popfl\n" 1048 #endif 1049 " ret\n" 1050 ".size __kretprobe_trampoline, .-__kretprobe_trampoline\n" 1051 ); 1052 NOKPROBE_SYMBOL(__kretprobe_trampoline); 1053 /* 1054 * __kretprobe_trampoline() skips updating frame pointer. The frame pointer 1055 * saved in trampoline_handler() points to the real caller function's 1056 * frame pointer. Thus the __kretprobe_trampoline() doesn't have a 1057 * standard stack frame with CONFIG_FRAME_POINTER=y. 1058 * Let's mark it non-standard function. Anyway, FP unwinder can correctly 1059 * unwind without the hint. 1060 */ 1062 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org