[kbuild-all] [tip:x86/entry 23/80] arch/x86/entry/common.c:234:24: warning: no previous prototype for function 'prepare_exit_to_usermode'

tree: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/entry head: 095b7a3e7745e6fb7cf0a1c09967c4f43e76f8f4 commit: aa9712e07f82a5458f2f16c100c491d736240d60 [23/80] x86/entry/common: Protect against instrumentation config: x86_64-allyesconfig (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project e6658079aca6d971b4e9d7137a3a2ecbc9c34aec) reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install x86_64 cross compiling tool for clang build # apt-get install binutils-x86-64-linux-gnu git checkout aa9712e07f82a5458f2f16c100c491d736240d60 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross 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 warnings (new ones prefixed by >>, old ones prefixed by <<): __visible noinstr void prepare_exit_to_usermode(struct pt_regs *regs) ^ arch/x86/entry/common.c:234:19: note: declare 'static' if the function is not intended to be used outside of this translation unit __visible noinstr void prepare_exit_to_usermode(struct pt_regs *regs) ^ static __visible noinstr void syscall_return_slowpath(struct pt_regs *regs) ^ arch/x86/entry/common.c:296:19: note: declare 'static' if the function is not intended to be used outside of this translation unit __visible noinstr void syscall_return_slowpath(struct pt_regs *regs) ^ static 2 warnings generated. vim +/prepare_exit_to_usermode +234 arch/x86/entry/common.c 233 235 { 236 instrumentation_begin(); 237 __prepare_exit_to_usermode(regs); 238 instrumentation_end(); 239 exit_to_user_mode(); 240 } 241 242 #define SYSCALL_EXIT_WORK_FLAGS \ 243 (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \ 244 _TIF_SINGLESTEP | _TIF_SYSCALL_TRACEPOINT) 245 246 static void syscall_slow_exit_work(struct pt_regs *regs, u32 cached_flags) 247 { 248 bool step; 249 250 audit_syscall_exit(regs); 251 252 if (cached_flags & _TIF_SYSCALL_TRACEPOINT) 253 trace_sys_exit(regs, regs->ax); 254 255 /* 256 * If TIF_SYSCALL_EMU is set, we only get here because of 257 * TIF_SINGLESTEP (i.e. this is PTRACE_SYSEMU_SINGLESTEP). 258 * We already reported this syscall instruction in 259 * syscall_trace_enter(). 260 */ 261 step = unlikely( 262 (cached_flags & (_TIF_SINGLESTEP | _TIF_SYSCALL_EMU)) 263 == _TIF_SINGLESTEP); 264 if (step || cached_flags & _TIF_SYSCALL_TRACE) 265 tracehook_report_syscall_exit(regs, step); 266 } 267 268 static void __syscall_return_slowpath(struct pt_regs *regs) 269 { 270 struct thread_info *ti = current_thread_info(); 271 u32 cached_flags = READ_ONCE(ti->flags); 272 273 CT_WARN_ON(ct_state() != CONTEXT_KERNEL); 274 275 if (IS_ENABLED(CONFIG_PROVE_LOCKING) && 276 WARN(irqs_disabled(), "syscall %ld left IRQs disabled", regs->orig_ax)) 277 local_irq_enable(); 278 279 rseq_syscall(regs); 280 281 /* 282 * First do one-time work. If these work items are enabled, we 283 * want to run them exactly once per syscall exit with IRQs on. 284 */ 285 if (unlikely(cached_flags & SYSCALL_EXIT_WORK_FLAGS)) 286 syscall_slow_exit_work(regs, cached_flags); 287 288 local_irq_disable(); 289 __prepare_exit_to_usermode(regs); 290 } 291 292 /* 293 * Called with IRQs on and fully valid regs. Returns with IRQs off in a 294 * state such that we can immediately switch to user mode. 295 */ 297 { 298 instrumentation_begin(); 299 __syscall_return_slowpath(regs); 300 instrumentation_end(); 301 exit_to_user_mode(); 302 } 303 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org