linux-kernel - Re: [tip:x86/mm 1/23] arch/x86/mm/init.c:75:6: warning: no previous prototype for function 'x86_has_pat

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Message-ID: <20200519205505.GD444@zn.tnic>
Date:   Tue, 19 May 2020 22:55:05 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     kbuild test robot <lkp@...el.com>
Cc:     Christoph Hellwig <hch@....de>, kbuild-all@...ts.01.org,
        clang-built-linux@...glegroups.com, linux-kernel@...r.kernel.org,
        x86@...nel.org, Benjamin Thiel <b.thiel@...teo.de>
Subject: Re: [tip:x86/mm 1/23] arch/x86/mm/init.c:75:6: warning: no previous
 prototype for function 'x86_has_pat_wp'

On Wed, May 20, 2020 at 01:51:25AM +0800, kbuild test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/mm
> head:   bd1de2a7aace4d1d312fb1be264b8fafdb706208
> commit: 1f6f655e01adebf5bd5e6c3da2e843c104ded051 [1/23] x86/mm: Add a x86_has_pat_wp() helper
> config: x86_64-randconfig-r012-20200519 (attached as .config)
> compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 135b877874fae96b4372c8a3fbfaa8ff44ff86e3)
> reproduce:
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         # install x86_64 cross compiling tool for clang build
>         # apt-get install binutils-x86-64-linux-gnu
>         git checkout 1f6f655e01adebf5bd5e6c3da2e843c104ded051
>         # save the attached .config to linux build tree
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kbuild test robot <lkp@...el.com>
> 
> All warnings (new ones prefixed by >>, old ones prefixed by <<):
> 
> >> arch/x86/mm/init.c:75:6: warning: no previous prototype for function 'x86_has_pat_wp' [-Wmissing-prototypes]
> bool x86_has_pat_wp(void)
> ^

Triggers with gcc too:

make W=1 arch/x86/mm/init.o

...

arch/x86/mm/init.c:81:6: warning: no previous prototype for ‘x86_has_pat_wp’ [-Wmissing-prototypes]
   81 | bool x86_has_pat_wp(void)
      |      ^~~~~~~~~~~~~~


-Wmissing-prototypes is default off, though, dunno why clang 11 has it
on.

Anyway, something for Benni to fix. CCed and leaving the rest for him as
reference.

> arch/x86/mm/init.c:75:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
> bool x86_has_pat_wp(void)
> ^
> static
> arch/x86/mm/init.c:866:13: warning: no previous prototype for function 'mem_encrypt_free_decrypted_mem' [-Wmissing-prototypes]
> void __weak mem_encrypt_free_decrypted_mem(void) { }
> ^
> arch/x86/mm/init.c:866:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
> void __weak mem_encrypt_free_decrypted_mem(void) { }
> ^
> static
> 2 warnings generated.
> 
> vim +/x86_has_pat_wp +75 arch/x86/mm/init.c
> 
>     73	
>     74	/* Check that the write-protect PAT entry is set for write-protect */
>   > 75	bool x86_has_pat_wp(void)
>     76	{
>     77		return __pte2cachemode_tbl[_PAGE_CACHE_MODE_WP] == _PAGE_CACHE_MODE_WP;
>     78	}
>     79	
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org



-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette