arch/riscv/include/asm/vdso/processor.h:14:2: error: implicit declaration of function 'barrier'

From: kernel test robot <lkp@intel.com>
To: Arvind Sankar <nivedita@alum.mit.edu>
Cc: kbuild-all@lists.01.org, linux-kernel@vger.kernel.org,
	Randy Dunlap <rdunlap@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux Memory Management List <linux-mm@kvack.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Kees Cook <keescook@chromium.org>
Subject: arch/riscv/include/asm/vdso/processor.h:14:2: error: implicit declaration of function 'barrier'
Date: Sun, 22 Nov 2020 02:39:17 +0800	[thread overview]
Message-ID: <202011220213.McOuf9IB-lkp@intel.com> (raw)

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   27bba9c532a8d21050b94224ffd310ad0058c353
commit: 3347acc6fcd4ee71ad18a9ff9d9dac176b517329 compiler.h: fix barrier_data() on clang
date:   7 days ago
config: riscv-randconfig-r003-20201121 (attached as .config)
compiler: riscv32-linux-gcc (GCC) 9.3.0
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=3347acc6fcd4ee71ad18a9ff9d9dac176b517329
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 3347acc6fcd4ee71ad18a9ff9d9dac176b517329
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=riscv 

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

All errors (new ones prefixed by >>):

   In file included from include/vdso/processor.h:10,
                    from arch/riscv/include/asm/processor.h:11,
                    from include/linux/prefetch.h:15,
                    from drivers/net/ethernet/intel/ixgb/ixgb_main.c:6:
   arch/riscv/include/asm/vdso/processor.h: In function 'cpu_relax':
>> arch/riscv/include/asm/vdso/processor.h:14:2: error: implicit declaration of function 'barrier' [-Werror=implicit-function-declaration]
      14 |  barrier();
         |  ^~~~~~~
   cc1: some warnings being treated as errors

vim +/barrier +14 arch/riscv/include/asm/vdso/processor.h

ad5d1122b82fbd6 Vincent Chen 2020-06-09   6  
ad5d1122b82fbd6 Vincent Chen 2020-06-09   7  static inline void cpu_relax(void)
ad5d1122b82fbd6 Vincent Chen 2020-06-09   8  {
ad5d1122b82fbd6 Vincent Chen 2020-06-09   9  #ifdef __riscv_muldiv
ad5d1122b82fbd6 Vincent Chen 2020-06-09  10  	int dummy;
ad5d1122b82fbd6 Vincent Chen 2020-06-09  11  	/* In lieu of a halt instruction, induce a long-latency stall. */
ad5d1122b82fbd6 Vincent Chen 2020-06-09  12  	__asm__ __volatile__ ("div %0, %0, zero" : "=r" (dummy));
ad5d1122b82fbd6 Vincent Chen 2020-06-09  13  #endif
ad5d1122b82fbd6 Vincent Chen 2020-06-09 @14  	barrier();
ad5d1122b82fbd6 Vincent Chen 2020-06-09  15  }
ad5d1122b82fbd6 Vincent Chen 2020-06-09  16  

:::::: The code at line 14 was first introduced by commit
:::::: ad5d1122b82fbd6a816d1b9d26ee01a6dbc2d757 riscv: use vDSO common flow to reduce the latency of the time-related functions

:::::: TO: Vincent Chen <vincent.chen@sifive.com>
:::::: CC: Palmer Dabbelt <palmerdabbelt@google.com>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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