tree: https://git.kernel.org/pub/scm/linux/kernel/git/joro/linux.git sev-es-client-v5.8-rc4 head: 7ee5e0ddab7fa6efbf0937f175a5688a375d55b8 commit: ba5a7a670ef6e070d2db31d286e1073e609311e1 [47/75] x86/entry/64: Add entry code for #VC handler config: x86_64-allyesconfig (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 02946de3802d3bc65bc9f2eb9b8d4969b5a7add8) 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 # install x86_64 cross compiling tool for clang build # apt-get install binutils-x86-64-linux-gnu git checkout ba5a7a670ef6e070d2db31d286e1073e609311e1 # 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: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): asmlinkage __visible noinstr struct pt_regs *vc_switch_off_ist(struct pt_regs *eregs) ^ arch/x86/kernel/traps.c:681:30: note: declare 'static' if the function is not intended to be used outside of this translation unit asmlinkage __visible noinstr struct pt_regs *vc_switch_off_ist(struct pt_regs *eregs) ^ static 1 warning generated. vim +/vc_switch_off_ist +681 arch/x86/kernel/traps.c 679 680 #ifdef CONFIG_AMD_MEM_ENCRYPT 682 { 683 unsigned long sp, *stack; 684 struct stack_info info; 685 struct pt_regs *regs; 686 687 /* 688 * In the SYSCALL entry path the RSP value comes from user-space - don't 689 * trust it and switch to the current kernel stack 690 */ 691 if (eregs->ip >= (unsigned long)entry_SYSCALL_64 && 692 eregs->ip < (unsigned long)entry_SYSCALL_64_safe_stack) { 693 sp = this_cpu_read(cpu_current_top_of_stack); 694 goto sync; 695 } 696 697 /* 698 * From here on the the RSP value is trusted - more RSP sanity checks 699 * need to happen above. 700 * 701 * Check whether entry happened from a safe stack. 702 */ 703 sp = eregs->sp; 704 stack = (unsigned long *)sp; 705 get_stack_info_noinstr(stack, current, &info); 706 707 /* 708 * Don't sync to entry stack or other unknown stacks - use the fall-back 709 * stack instead. 710 */ 711 if (info.type == STACK_TYPE_UNKNOWN || info.type == STACK_TYPE_ENTRY || 712 info.type >= STACK_TYPE_EXCEPTION_LAST) 713 sp = __this_cpu_ist_top_va(VC2); 714 715 sync: 716 /* 717 * Found a safe stack - switch to it as if the entry didn't happen via 718 * IST stack. The code below only copies pt_regs, the real switch happens 719 * in assembly code. 720 */ 721 sp = ALIGN_DOWN(sp, 8) - sizeof(*regs); 722 723 regs = (struct pt_regs *)sp; 724 *regs = *eregs; 725 726 return regs; 727 } 728 #endif 729 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org