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Message-ID: <20200812030956.GA17005@xiangao.remote.csb>
Date: Wed, 12 Aug 2020 11:09:56 +0800
From: Gao Xiang <hsiangkao@...hat.com>
To: kernel test robot <lkp@...el.com>
Cc: Gao Xiang <hsiangkao@....com>, kbuild-all@...ts.01.org,
linux-kernel@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: arch/sparc/include/asm/cmpxchg_64.h:161:55: sparse: sparse: cast
truncates bits from constant value (ffffffffe0f510cc becomes cc)
Hi,
On Wed, Aug 12, 2020 at 09:49:38AM +0800, kernel test robot wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: fb893de323e2d39f7a1f6df425703a2edbdf56ea
> commit: 47e4937a4a7ca4184fd282791dfee76c6799966a erofs: move erofs out of staging
> date: 12 months ago
> config: sparc64-randconfig-s032-20200812 (attached as .config)
> compiler: sparc64-linux-gcc (GCC) 9.3.0
> reproduce:
> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # apt-get install sparse
> # sparse version: v0.6.2-168-g9554805c-dirty
> git checkout 47e4937a4a7ca4184fd282791dfee76c6799966a
> # save the attached .config to linux build tree
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=sparc64
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@...el.com>
>
>
> sparse warnings: (new ones prefixed by >>)
>
> fs/erofs/utils.c: note: in included file (through arch/sparc/include/asm/cmpxchg.h, arch/sparc/include/asm/atomic_64.h, arch/sparc/include/asm/atomic.h, ...):
> >> arch/sparc/include/asm/cmpxchg_64.h:161:55: sparse: sparse: cast truncates bits from constant value (ffffffffe0f510cc becomes cc)
> --
> fs/erofs/zdata.c: note: in included file (through arch/sparc/include/asm/cmpxchg.h, arch/sparc/include/asm/atomic_64.h, arch/sparc/include/asm/atomic.h, ...):
> >> arch/sparc/include/asm/cmpxchg_64.h:161:55: sparse: sparse: cast truncates bits from constant value (ffffffffe0f510cc becomes cc)
> arch/sparc/include/asm/cmpxchg_64.h:161:50: sparse: sparse: cast truncates bits from constant value (5f0ecafe becomes fe)
> arch/sparc/include/asm/cmpxchg_64.h:161:50: sparse: sparse: cast truncates bits from constant value (5f0ecafe becomes fe)
> arch/sparc/include/asm/cmpxchg_64.h:161:55: sparse: sparse: cast truncates bits from constant value (5f0edead becomes ad)
>
> vim +161 arch/sparc/include/asm/cmpxchg_64.h
>
> d550bbd40c0e10 David Howells 2012-03-28 155
> d550bbd40c0e10 David Howells 2012-03-28 156 static inline unsigned long
> d550bbd40c0e10 David Howells 2012-03-28 157 __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
> d550bbd40c0e10 David Howells 2012-03-28 158 {
> d550bbd40c0e10 David Howells 2012-03-28 159 switch (size) {
> a12ee2349312d7 Babu Moger 2017-05-24 160 case 1:
> a12ee2349312d7 Babu Moger 2017-05-24 @161 return __cmpxchg_u8(ptr, old, new);
> d550bbd40c0e10 David Howells 2012-03-28 162 case 4:
> d550bbd40c0e10 David Howells 2012-03-28 163 return __cmpxchg_u32(ptr, old, new);
> d550bbd40c0e10 David Howells 2012-03-28 164 case 8:
> d550bbd40c0e10 David Howells 2012-03-28 165 return __cmpxchg_u64(ptr, old, new);
> d550bbd40c0e10 David Howells 2012-03-28 166 }
> d550bbd40c0e10 David Howells 2012-03-28 167 __cmpxchg_called_with_bad_pointer();
> d550bbd40c0e10 David Howells 2012-03-28 168 return old;
> d550bbd40c0e10 David Howells 2012-03-28 169 }
> d550bbd40c0e10 David Howells 2012-03-28 170
Again, I have no idea how to deal with that in my current
gatekeeping code.
I got these reports, but I cannot help to resolve that.
Even I don't know if that's another sparse issue (since I
only got such reports on sparc and alpha arch, but no x86
or arm64.)
https://lore.kernel.org/r/202007251532.y5A10ZoO%25lkp@intel.com
https://lore.kernel.org/r/202007272132.1AgbBO3U%25lkp@intel.com
https://lore.kernel.org/r/202008100408.Wc6WGrac%25lkp@intel.com
https://lore.kernel.org/r/202008120933.YrVhHyoA%25lkp@intel.com
If no one can help that, could you please silence such reports.
It really makes me confusing.
Thanks,
Gao Xiang
>
> :::::: The code at line 161 was first introduced by commit
> :::::: a12ee2349312d7112b9b7c6ac2e70c5ec2ca334e arch/sparc: Introduce cmpxchg_u8 SPARC
>
> :::::: TO: Babu Moger <babu.moger@...cle.com>
> :::::: CC: David S. Miller <davem@...emloft.net>
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
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