Re: [PATCH v2 2/5] powerpc/lib: Initialize a temporary mm for code patching

Hi "Christopher,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on powerpc/next]
[also build test WARNING on char-misc/char-misc-testing v5.8-rc5 next-20200716]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Christopher-M-Riedl/Use-per-CPU-temporary-mappings-for-patching/20200709-123827
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-randconfig-r013-20200717 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project ed6b578040a85977026c93bf4188f996148f3218)
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 powerpc cross compiling tool for clang build
        # apt-get install binutils-powerpc-linux-gnu
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc 

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

All warnings (new ones prefixed by >>):

quoted

arch/powerpc/lib/code-patching.c:53:13: warning: no previous prototype for function 'poking_init' [-Wmissing-prototypes]

   void __init poking_init(void)
               ^
   arch/powerpc/lib/code-patching.c:53:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void __init poking_init(void)
   ^
   static 
   1 warning generated.

vim +/poking_init +53 arch/powerpc/lib/code-patching.c

    52	
  > 53	void __init poking_init(void)
    54	{
    55		spinlock_t *ptl; /* for protecting pte table */
    56		pte_t *ptep;
    57	
    58		/*
    59		 * Some parts of the kernel (static keys for example) depend on
    60		 * successful code patching. Code patching under STRICT_KERNEL_RWX
    61		 * requires this setup - otherwise we cannot patch at all. We use
    62		 * BUG_ON() here and later since an early failure is preferred to
    63		 * buggy behavior and/or strange crashes later.
    64		 */
    65		patching_mm = copy_init_mm();
    66		BUG_ON(!patching_mm);
    67	
    68		/*
    69		 * In hash we cannot go above DEFAULT_MAP_WINDOW easily.
    70		 * XXX: Do we want additional bits of entropy for radix?
    71		 */
    72		patching_addr = (get_random_long() & PAGE_MASK) %
    73			(DEFAULT_MAP_WINDOW - PAGE_SIZE);
    74	
    75		ptep = get_locked_pte(patching_mm, patching_addr, &ptl);
    76		BUG_ON(!ptep);
    77		pte_unmap_unlock(ptep, ptl);
    78	}
    79	

---
0-DAY CI Kernel Test Service, Intel Corporation
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