linux-kernel - Re: [PATCH V2 2/2] mm/mmap: Drop generic protection

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Date:   Tue, 14 Jun 2022 08:35:51 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     kernel test robot <lkp@...el.com>, linux-mm@...ck.org
Cc:     kbuild-all@...ts.01.org, Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 2/2] mm/mmap: Drop generic protection_map[] array



On 6/13/22 16:43, kernel test robot wrote:
> Hi Anshuman,
> 
> Thank you for the patch! Yet something to improve:
> 
> [auto build test ERROR on akpm-mm/mm-everything]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Anshuman-Khandual/mm-mmap-Drop-__SXXX-__PXXX-macros-from-across-platforms/20220613-133456
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
> config: powerpc64-randconfig-r016-20220613 (https://download.01.org/0day-ci/archive/20220613/202206131931.ZJuanaBo-lkp@intel.com/config)
> compiler: powerpc64le-linux-gcc (GCC) 11.3.0
> 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://github.com/intel-lab-lkp/linux/commit/696f81b49f7b6316f652d795da4c0008efef4487
>         git remote add linux-review https://github.com/intel-lab-lkp/linux
>         git fetch --no-tags linux-review Anshuman-Khandual/mm-mmap-Drop-__SXXX-__PXXX-macros-from-across-platforms/20220613-133456
>         git checkout 696f81b49f7b6316f652d795da4c0008efef4487
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash arch/powerpc/mm/book3s64/
> 
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@...el.com>
> 
> All errors (new ones prefixed by >>):
> 
>    In file included from arch/powerpc/include/asm/page.h:306,
>                     from arch/powerpc/include/asm/mmu.h:149,
>                     from arch/powerpc/include/asm/lppaca.h:46,
>                     from arch/powerpc/include/asm/paca.h:18,
>                     from arch/powerpc/include/asm/current.h:13,
>                     from include/linux/sched.h:12,
>                     from arch/powerpc/mm/book3s64/pgtable.c:6:
>    arch/powerpc/mm/book3s64/pgtable.c: In function 'vm_get_page_prot':
>>> arch/powerpc/mm/book3s64/pgtable.c:557:41: error: 'protection_map' undeclared (first use in this function)
>      557 |         unsigned long prot = pgprot_val(protection_map[vm_flags &
>          |                                         ^~~~~~~~~~~~~~

Adding an extern declaration fixes the problem. The problem is generic declaration
in include/linux/mm.h is not available for platforms with ARCH_HAS_VM_GET_PAGE_PROT.
protection_map[] has to be moved into arch/powerpc/mm/pgtable.c to be used by both
32 bit and 64 bit platforms.

diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c                                                                                                                                                                                              
index 260b0cc6d3a1..99c794ab253d 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c                        
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -551,6 +551,8 @@ unsigned long memremap_compat_align(void)
 EXPORT_SYMBOL_GPL(memremap_compat_align);
 #endif
                                                                
+extern pgprot_t protection_map[16];
+                 
 /* Note due to the way vm flags are laid out, the bits are XWR */
 pgprot_t vm_get_page_prot(unsigned long vm_flags)
 {