Re: [kbuild-all] Re: [PATCH v2 6/9] KVM: arm64: Detect and handle hypervisor stack overflows

[Marc Zyngier]

On 2022-02-23 12:34, Philip Li wrote:
> On Wed, Feb 23, 2022 at 09:16:59AM +0000, Marc Zyngier wrote:
> > On Wed, 23 Feb 2022 09:05:18 +0000,
> > kernel test robot <lkp@xxxxxxxxx> wrote:
> > >
> > > Hi Kalesh,
> > >
> > > Thank you for the patch! Perhaps something to improve:
> > >
> > > [auto build test WARNING on cfb92440ee71adcc2105b0890bb01ac3cddb8507]
> > >
> > > url:    https://github.com/0day-ci/linux/commits/Kalesh-Singh/KVM-arm64-Hypervisor-stack-enhancements/20220223-010522
> > > base:   cfb92440ee71adcc2105b0890bb01ac3cddb8507
> > > config: arm64-randconfig-r011-20220221 (https://download.01.org/0day-ci/archive/20220223/202202231727.L621fVgD-lkp@xxxxxxxxx/config)
> > > compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project d271fc04d5b97b12e6b797c6067d3c96a8d7470e)
> > > 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
> > >         # install arm64 cross compiling tool for clang build
> > >         # apt-get install binutils-aarch64-linux-gnu
> > >         # https://github.com/0day-ci/linux/commit/7fe99fd40f7c4b2973218045ca5b9c9160524db1
> > >         git remote add linux-review https://github.com/0day-ci/linux
> > >         git fetch --no-tags linux-review Kalesh-Singh/KVM-arm64-Hypervisor-stack-enhancements/20220223-010522
> > >         git checkout 7fe99fd40f7c4b2973218045ca5b9c9160524db1
> > >         # save the config file to linux build tree
> > >         mkdir build_dir
> > >         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash arch/arm64/
> > >
> > > If you fix the issue, kindly add following tag as appropriate
> > > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > >
> > > All warnings (new ones prefixed by >>):
> > >
> > >    include/linux/stddef.h:8:14: note: expanded from macro 'NULL'
> > >    #define NULL ((void *)0)
> > >                 ^~~~~~~~~~~
> > >    arch/arm64/kvm/hyp/nvhe/switch.c:200:27: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
> > >            [ESR_ELx_EC_FP_ASIMD]           = kvm_hyp_handle_fpsimd,
> > >                                              ^~~~~~~~~~~~~~~~~~~~~
> > >    arch/arm64/kvm/hyp/nvhe/switch.c:196:28: note: previous initialization is here
> > >            [0 ... ESR_ELx_EC_MAX]          = NULL,
> > >                                              ^~~~
> > >    include/linux/stddef.h:8:14: note: expanded from macro 'NULL'
> > >    #define NULL ((void *)0)
> > >                 ^~~~~~~~~~~
> >
> > Kalesh, please ignore this nonsense. There may be things to improve,
> > but this is *NOT* one of them.
> >
> > These reports are pretty useless, and just lead people to ignore real
> > bug reports.
>
> Hi Kalesh, sorry there're some irrelevant issues mixed in the report,
> kindly ignore them. And the valuable ones are the new ones that
> prefixed by >>, as the below one in original report.
>
> > > arch/arm64/kvm/hyp/nvhe/switch.c:372:17: warning: no previous 
> > > prototype for function 'hyp_panic_bad_stack' [-Wmissing-prototypes]
>    void __noreturn hyp_panic_bad_stack(void)
>                    ^

This is only called from assembly code, so a prototype wouldn't bring 
much.

        M.
--
Jazz is not dead. It just smells funny...