Re: [linux-stable-rc:linux-5.10.y 7109/7120] arch/x86/kernel/cpu/bugs.c:57:21: warning: section attribute is specified on redeclared variable

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Jul 12, 2022 at 01:24:27PM -0700, Nathan Chancellor wrote:
> On Tue, Jul 12, 2022 at 01:21:15PM -0700, Nathan Chancellor wrote:
> > On Wed, Jul 13, 2022 at 04:07:25AM +0800, kernel test robot wrote:
> > > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git linux-5.10.y
> > > head:   ba398a0e54049bb6a1c102245ae84103f103ff2c
> > > commit: 855b78ccf1c8c952e148bdbd234cde117b098060 [7109/7120] KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS
> > > config: i386-randconfig-a013 (https://download.01.org/0day-ci/archive/20220713/202207130344.AUqExE4E-lkp@intel.com/config)
> > > compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project badda4ac3c489a8c8cccdad1f74b9308c350a9e0)
> > > 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://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git/commit/?id=855b78ccf1c8c952e148bdbd234cde117b098060
> > >         git remote add linux-stable-rc https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git
> > >         git fetch --no-tags linux-stable-rc linux-5.10.y
> > >         git checkout 855b78ccf1c8c952e148bdbd234cde117b098060
> > >         # save the config file
> > >         mkdir build_dir && cp config build_dir/.config
> > >         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash arch/x86/kernel/
> > > 
> > > If you fix the issue, kindly add following tag where applicable
> > > Reported-by: kernel test robot <lkp@intel.com>
> > > 
> > > All warnings (new ones prefixed by >>):
> > > 
> > > >> arch/x86/kernel/cpu/bugs.c:57:21: warning: section attribute is specified on redeclared variable [-Wsection]
> > >    DEFINE_PER_CPU(u64, x86_spec_ctrl_current);
> > >                        ^
> > >    arch/x86/include/asm/nospec-branch.h:278:12: note: previous declaration is here
> > >    extern u64 x86_spec_ctrl_current;
> > >               ^
> > >    1 warning generated.
> > > 
> > > 
> > > vim +57 arch/x86/kernel/cpu/bugs.c
> > > 
> > > c40221c4c496c5 Peter Zijlstra 2022-06-14  55  
> > > c40221c4c496c5 Peter Zijlstra 2022-06-14  56  /* The current value of the SPEC_CTRL MSR with task-specific bits set */
> > > c40221c4c496c5 Peter Zijlstra 2022-06-14 @57  DEFINE_PER_CPU(u64, x86_spec_ctrl_current);
> > > c40221c4c496c5 Peter Zijlstra 2022-06-14  58  EXPORT_SYMBOL_GPL(x86_spec_ctrl_current);
> > > c40221c4c496c5 Peter Zijlstra 2022-06-14  59  
> > > 
> > > :::::: The code at line 57 was first introduced by commit
> > > :::::: c40221c4c496c5c026ede111094a96f292875d88 x86/bugs: Keep a per-CPU IA32_SPEC_CTRL value
> > > 
> > > :::::: TO: Peter Zijlstra <peterz@infradead.org>
> > > :::::: CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > > 
> > > -- 
> > > 0-DAY CI Kernel Test Service
> > > https://01.org/lkp
> > > 
> > 
> > Looks like that declaration should be using DECLARE_PER_CPU?
> 
> Additionally, this appears to be an issue on mainline, our CI is
> starting to roll in with these patches (clang-13 + x86_64 allmodconfig):
> 
> https://github.com/ClangBuiltLinux/continuous-integration2/actions/runs/2658541992
> 
> https://builds.tuxbuild.com/2Br2Q4juY6VKxbmgzULKe5C3pGq/build.log
> 
> I am happy to send a patch if this is correct, unless someone else wants
> to.

Please do so.

thanks,

greg k-h