[arm-platforms:kvm-arm64/mmu/guest-MMIO-guard 18/18] mm/ioremap.c:31:13: warning: no previous prototype for function 'ioremap_page_range_hook'

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git kvm-arm64/mmu/guest-MMIO-guard
head:   63d0c848f6eeb82c8abbdc836c6c71a1c907a5cd
commit: 63d0c848f6eeb82c8abbdc836c6c71a1c907a5cd [18/18] guest hacks
config: s390-randconfig-r035-20210622 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project b259740801d3515810ecc15bf0c24b0d476a1608)
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 s390 cross compiling tool for clang build
        # apt-get install binutils-s390x-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?id=63d0c848f6eeb82c8abbdc836c6c71a1c907a5cd
        git remote add arm-platforms https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git
        git fetch --no-tags arm-platforms kvm-arm64/mmu/guest-MMIO-guard
        git checkout 63d0c848f6eeb82c8abbdc836c6c71a1c907a5cd
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=s390 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All warnings (new ones prefixed by >>):

   In file included from mm/ioremap.c:12:
   In file included from include/linux/io.h:13:
   In file included from arch/s390/include/asm/io.h:75:
   include/asm-generic/io.h:464:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __raw_readb(PCI_IOBASE + addr);
                             ~~~~~~~~~~ ^
   include/asm-generic/io.h:477:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/big_endian.h:36:59: note: expanded from macro '__le16_to_cpu'
   #define __le16_to_cpu(x) __swab16((__force __u16)(__le16)(x))
                                                             ^
   include/uapi/linux/swab.h:102:54: note: expanded from macro '__swab16'
   #define __swab16(x) (__u16)__builtin_bswap16((__u16)(x))
                                                        ^
   In file included from mm/ioremap.c:12:
   In file included from include/linux/io.h:13:
   In file included from arch/s390/include/asm/io.h:75:
   include/asm-generic/io.h:490:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/big_endian.h:34:59: note: expanded from macro '__le32_to_cpu'
   #define __le32_to_cpu(x) __swab32((__force __u32)(__le32)(x))
                                                             ^
   include/uapi/linux/swab.h:115:54: note: expanded from macro '__swab32'
   #define __swab32(x) (__u32)__builtin_bswap32((__u32)(x))
                                                        ^
   In file included from mm/ioremap.c:12:
   In file included from include/linux/io.h:13:
   In file included from arch/s390/include/asm/io.h:75:
   include/asm-generic/io.h:501:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writeb(value, PCI_IOBASE + addr);
                               ~~~~~~~~~~ ^
   include/asm-generic/io.h:511:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   include/asm-generic/io.h:521:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   include/asm-generic/io.h:609:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           readsb(PCI_IOBASE + addr, buffer, count);
                  ~~~~~~~~~~ ^
   include/asm-generic/io.h:617:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           readsw(PCI_IOBASE + addr, buffer, count);
                  ~~~~~~~~~~ ^
   include/asm-generic/io.h:625:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           readsl(PCI_IOBASE + addr, buffer, count);
                  ~~~~~~~~~~ ^
   include/asm-generic/io.h:634:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           writesb(PCI_IOBASE + addr, buffer, count);
                   ~~~~~~~~~~ ^
   include/asm-generic/io.h:643:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           writesw(PCI_IOBASE + addr, buffer, count);
                   ~~~~~~~~~~ ^
   include/asm-generic/io.h:652:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           writesl(PCI_IOBASE + addr, buffer, count);
                   ~~~~~~~~~~ ^

quoted

mm/ioremap.c:31:13: warning: no previous prototype for function 'ioremap_page_range_hook' [-Wmissing-prototypes]

   void __weak ioremap_page_range_hook(unsigned long addr, unsigned long end,
               ^
   mm/ioremap.c:31:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void __weak ioremap_page_range_hook(unsigned long addr, unsigned long end,
   ^
   static 
   13 warnings generated.


vim +/ioremap_page_range_hook +31 mm/ioremap.c

    30	
  > 31	void __weak ioremap_page_range_hook(unsigned long addr, unsigned long end,
    32					    phys_addr_t phys_addr, pgprot_t prot)
    33	{
    34	}
    35	

---
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