Re: [RFC] arm64: properly define SOFT_DIRTY for arm64

[kernel test robot <lkp@intel.com>]

Hi Nico,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build errors:

[auto build test ERROR on arm64/for-next/core]
[also build test ERROR on arm/for-next arm/fixes kvmarm/next soc/for-next linus/master v6.4 next-20230703]
[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#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Nico-Pache/arm64-properly-define-SOFT_DIRTY-for-arm64/20230703-220825
base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
patch link:    https://lore.kernel.org/r/20230703135526.930004-1-npache%40redhat.com
patch subject: [RFC] arm64: properly define SOFT_DIRTY for arm64
config: arm64-allyesconfig (https://download.01.org/0day-ci/archive/20230704/202307041014.1YFuFmew-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 12.3.0
reproduce: (https://download.01.org/0day-ci/archive/20230704/202307041014.1YFuFmew-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202307041014.1YFuFmew-lkp@intel.com/

All errors (new ones prefixed by >>):

   scripts/genksyms/parse.y: warning: 9 shift/reduce conflicts [-Wconflicts-sr]
   scripts/genksyms/parse.y: warning: 5 reduce/reduce conflicts [-Wconflicts-rr]
   scripts/genksyms/parse.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
   In file included from include/linux/pgtable.h:6,
                    from arch/arm64/include/asm/io.h:12,
                    from include/linux/io.h:13,
                    from include/acpi/acpi_io.h:5,
                    from include/linux/acpi.h:37,
                    from include/acpi/apei.h:9,
                    from include/acpi/ghes.h:5,
                    from include/linux/arm_sdei.h:8,
                    from arch/arm64/kernel/asm-offsets.c:10:
   arch/arm64/include/asm/pgtable.h: In function 'pte_clear_soft_dirty':
>> arch/arm64/include/asm/pgtable.h:1110:13: error: implicit declaration of function 'arch_faults_on_old_pte' [-Werror=implicit-function-declaration]
    1110 |         if (arch_faults_on_old_pte())
         |             ^~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors
   make[2]: *** [scripts/Makefile.build:114: arch/arm64/kernel/asm-offsets.s] Error 1
   make[2]: Target 'prepare' not remade because of errors.
   make[1]: *** [Makefile:1287: prepare0] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:226: __sub-make] Error 2
   make: Target 'prepare' not remade because of errors.


vim +/arch_faults_on_old_pte +1110 arch/arm64/include/asm/pgtable.h

  1099	
  1100	#ifdef CONFIG_ARM64_HW_AFDBM
  1101	/*
  1102	 * if we have the DBM bit we can utilize the software dirty bit as
  1103	 * a mechanism to introduce the soft_dirty functionality; however, without
  1104	 * it this bit is crucial to determining if a entry is dirty and we cannot
  1105	 * clear it via software. DBM can also be disabled or broken on some early
  1106	 * armv8 devices, so check its availability before modifying it.
  1107	 */
  1108	static inline pte_t pte_clear_soft_dirty(pte_t pte)
  1109	{
> 1110		if (arch_faults_on_old_pte())
  1111			return pte;
  1112	
  1113		return clear_pte_bit(pte, __pgprot(PTE_DIRTY));
  1114	}
  1115	

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