Hi Joey,

FYI, the error/warning still remains.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   576e61cea1e4b66f52f164dee0edbe4b1c999997
commit: 4e3bca8f7cdd3b658ee7ad700fdce95b5e13a441 arm64: alternative: patch alternatives in the vDSO
date:   7 weeks ago
config: arm64-alldefconfig
compiler: aarch64-linux-gcc (GCC) 12.1.0
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/?id=4e3bca8f7cdd3b658ee7ad700fdce95b5e13a441
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 4e3bca8f7cdd3b658ee7ad700fdce95b5e13a441
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash arch/arm64/kernel/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> arch/arm64/kernel/alternative.c:198:6: warning: no previous prototype for 'apply_alternatives_vdso' [-Wmissing-prototypes]
     198 | void apply_alternatives_vdso(void)
         |      ^~~~~~~~~~~~~~~~~~~~~~~


vim +/apply_alternatives_vdso +198 arch/arm64/kernel/alternative.c

   197	
 > 198	void apply_alternatives_vdso(void)
   199	{
   200		struct alt_region region;
   201		const struct elf64_hdr *hdr;
   202		const struct elf64_shdr *shdr;
   203		const struct elf64_shdr *alt;
   204		DECLARE_BITMAP(all_capabilities, ARM64_NPATCHABLE);
   205	
   206		bitmap_fill(all_capabilities, ARM64_NPATCHABLE);
   207	
   208		hdr = (struct elf64_hdr *)vdso_start;
   209		shdr = (void *)hdr + hdr->e_shoff;
   210		alt = find_section(hdr, shdr, ".altinstructions");
   211		if (!alt)
   212			return;
   213	
   214		region = (struct alt_region){
   215			.begin	= (void *)hdr + alt->sh_offset,
   216			.end	= (void *)hdr + alt->sh_offset + alt->sh_size,
   217		};
   218	
   219		__apply_alternatives(&region, false, &all_capabilities[0]);
   220	}
   221	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp